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[Question] [ Assume I have a human colony on The Moon. A meteor fragment gets by the defense system and smashes into a portion of the dome, let's say the hole is 1 meter in diameter, it's big. Safety measures come into play and the section is sealed off. So only the one section is experiencing decompression. But the hole is large, so air is escaping fast. Two questions. 1) Would the rush of air further damage the hole, assuming reasonable precautions against this were made? Whether it's multiple layers or whatever. 2) The main question though - would this incident ever cause the habitat section to explode? I am writing a novella where there is a ticking time element. Certainly part of this is that the air is going for the people there. It would be nice to have the extra dram of further structural damage/danger imminent from the hole - but I don't want to introduce that if that really wouldn't happen. [Answer] A 1 meter hole in a dome's superstructure is likely to severely damage something else below it. If you need an "its gonna blow in 5 minutes!" story element, have the impact cause fires that are threatening the Fuel or Oxygen storage. Use the loss of pressurization and escaping atmosphere as something that hinders the efforts to repair the damage. Here are some quick estimates so you can get an idea what this looks like: Assuming a 20 meter radius dome (approx 132 feet wide) with a 1 meter hole and a shell that's 0.5 meters thick and is pressurized at 1 atm. According to this site's tool - <https://www.copely.com/tools/flow-rate-calculator/> - **The flow rate will be about 10,000,000 liters per minute.** The volume of your hemisphere will be around 16 million liters. Assuming the pressure stays the same in the dome, its will vent all **16 million liters in around 2 minutes - updated figures**. Realistically you will lose pressure as the air vents from the dome, so it will take longer. At half pressure the flow rate is still about 500,000 liters per minute though, so it doesn't slow down that much. You can keep the pressure in the dome "stable" by having an oxygen leak fueling a raging fire, creating smoke and CO2 that replaces the previously breathable air. If you don't do something like that and allow the pressure to decrease and air to vent, your dome will have LESS of a chance of exploding since fire needs oxygen to burn. Another consideration is that the dome might rely on the air pressure inside to keep it up supported. Removing the air might cause the ceiling to collapse, but not explode outwards, it will implode inwards. In regards to point 1) yeah the flowing air can cause more damage, but likely only to the immediate area surrounding the impact. You could have a meteor punch only a small hole at first, but the damage to the surrounding material causes it to grow as air rushes out, settling at your 1m diameter. [Answer] The structure wouldn't *explode*, but it may fall on the colonists. Under normal operation, the colony hab dome expects 1 atm of air pressure inside, and nearly no pressure outside. This is a dramatic difference in air pressure, and the dome is a large, complex structure made from the lightest high-tension materials possible: A vast network of cabling that holds in place the air-tight panels, and keeps the panels under enough pressure so that they don't fly apart from the pressure on the inside. The dome structure needs to be lightweight, because its material was shipped from Earth... The moon doesn't (yet, and may never) have the industry to create these cables and panels from resources found on the surface or available to be mined. Every ounce of material launched to the moon costs far more in fuel costs than it costs in manufacturing costs. Even though the dome is lightweight by structural standards, if it lands on a human, that human will still be squished, even in the 1/6th gravity of the moon. Such a structure would still fail catastrophically, though it wouldn't explode *per-se*. As the structure starts to buckle, it will make a horrendous amount of sound... and fortunately for the drama, it would start buckling long before too much air has escaped to make audible noise, so the colonists will hear their doom coming. [Answer] No. But you can construct a scenario where it might. Good design practice would likely be to build a series of double-walled bubbles, airlocked together, and maybe have some sort of active sealer that “clots” when exposed to air. A really cool looking alternative would be to have a big atrium/mezzanine with a giant glasslike wall. If artificial sapphire (or whatever other unobtanium) can be grown into arbitrary shapes, it can be an expensive, safer alternative to the material elsewhere (the bubbles get punctured by meteorites as small as 1kg, which is rare but causes constant maintenance while the dome is unaffected by anything up to 100kg, which doesn’t come up, etc with the handwaving). Then the one-in-a-million meteorite punches through the dome. Someone slaps a patch on it, so it’s leaking slowly. But, oh no! Now that the dome structure has been compromised, cracks are slowly propagating. The bubbles are all sealed off from the mezzanine, and opening the air locks will send a pressure wave in, which could punch the glass out. If you really want an explosion, you need to compensate for having a leakier pressure vessel by turning the oxygen mix much purer. Near-pure O2 gives you all the excuse you need for a real explosion. ]
[Question] [ So this is very loosely inspired by a theory I have about Star Wars as a setting, but it is not something they really discuss overtly even in the Extended Universe. One of the interesting things about the setting is the fact that there really doesn't seem to be much in the way of technological progress. The only reason this could be the case for this long is if they have essentially discovered all of science. Everything from genetic engineering of behavioral traits to a theory of physics that incorporates something as unusual as hyperspace has already been done. Any technology we don't see must be a consequence of something else, like the metaphysics of The Force preventing the development of Trek style transporters and transhumanism or extreme insecurities leading to a lack of networked computers. What is interesting here is that any scientist would be either an engineer, who is applying principles that are already well understood, or an archaeologist, digging into things from the past lost to time. Engineering(and similar fields like medicine) is all about applying science that is already fairly well understood, with the focus on different types of tradeoffs. In the Star Wars example, one starfighter isn’t more advanced than another, it is simply a case of trading speed for survivability for cost. The Empire wants cheap and agile fighters while the Rebel Alliance wants durable ones that are useful against capital ships. Because the setting is so old an, past technology can still be competitive with that of the present. When this is combined with the age of the setting, it means that the only field of science that really has anything new to say is archaeology, because history has so often been lost to time in this context. What is nice about this angle is that history is generally more easily understood than a real scientific field, which makes it easier to come up with alternative theories that are something other than pure technobabble. It is much easier to think about causal connections in history and how those can be altered by new discoveries than it is to think about entirely fictional physics and metaphysics. AI/droids is also a factor here, in which they handle much of the technical work as well. We don’t really see human doctors all that much, with medical droids doing the overwhelming majority of the work. The same is likely at least partially true for engineers and archaeologists. There is probably a droid that does most of the calculations or digging. Does this seem plausible enough as part of the basis for a new setting? How long would you need this level of development for this to be plausible? [Answer] This is not only possible, but it is even postulated by serious science as a reason that we [haven't met other advanced civilisations yet](https://phys.org/pdf448874915.pdf). The debate all comes down to a concept called the technology ceiling; just how complex is the universe and how much is there to know about it? Ultimately, if the universe is complex and has a high technology ceiling, allowing for all kinds of technologies we haven't even thought of yet then we would expect other civilisations to have found at least some of this tech by now and be visiting us by FTL, wormhole, etc. On the other hand, if we already know a significant percentage of what there is to know about how the universe works, and there really IS no such thing as FTL, time travel, wormholes, etc. then there's nothing to learn that would bring advanced civilisations to our doorstep because we're already as close to the most advanced society that would be possible in such a universe. We really don't know which is true yet because so far, we're still advancing our knowledge. There are some big ticket items about how the universe works that we still don't understand and that persistently elude us though, and it may be that they elude us because the answers aren't really there. All that said - in physics there is a concept called a Grand Unified Theory. The idea is that all of the 5 fundamental forces we see in nature might one day be integrated into a single set of equations that define how they are all interrelated. If we crack that theory and we are still learning after that, then there is a good case for a high ceiling, otherwise it could spell the point at which our learning journey starts to radically slow down. What is so important about the GUT? Well the 5 fundamental forces are now really only 4 thanks to the Maxwell Equations in 1861, which unified Electrical Force and Magnetic Force. That theory paved the way for the massive wave of advances we have seen through the entire 20th and into the early 21st centuries as engineers and technicians learned how to practically apply the theory of this unification to deliver radio, kettles, lights, computers, and much more. Pretty much all our current technology is based on the unification of just two of these forces - what would we be capable of if we unified them all? The answer could be that we advance on the Kardeshev Scale and have incredible power in our hands. But, and most relevant to your question, the answer could *also* be 'not much'. Perhaps all the real utility in uniting the forces has already been gained from Electro-Magnetism. So from a reality-check perspective, it is certainly possible. It is even believed by serious scientists to be the most likely possibility in terms of what science has to offer in our universe. I suspect however that we will know within the next couple of centuries whether or not it is indeed the case as the unification of weak nuclear force with electro-magnetism is already being worked on at a steady clip by research scientists across the world. [Answer] **The more you know, the more you realise you don't** There is little evidence up till now that increasing rates of scientific discovery has decreased the apparent amount of knowledge yet to be discovered. In fact, the reverse is true. Over the last few centuries (or even the last few millennia) scientific answers have yielded many more questions than answers, and the rate of this disparity has actually increased recently. Discoveries in electromagnetism has yielded theories of relativity. But this results in more questions and puzzles. Discoveries in the quantum world has many theories, yet the standard model doesn't seem satisfactorily complete, and every new theory yields yet more discoveries to find. Even astronomy has given us puzzling discoveries like dark energy and dark matter. It seems the more we know, the more we don't know. Even in the world of Star Wars - it is unreasonable to conclude that all of physics or all scientific discoveries have been discovered. What about: * how hyperdrives destroy causality - what effects on time does this have? * if you could travel in an instant incredible distances, what about leaping to nearby galaxies, or even finding the edge of the universe? * if you could travel faster than light at all, is it possible to know about how the universe began? * artificial gravity abounds in Star Wars, what implications does this have for general relativity? What of space-time curvature? * what possible cause is there to have creatures that look remarkably similar to humans? Even Jabba the Hutt has 2 eyes, a nose and a mouth that looks Earth-like. What reason could there be where this evolutionary pathway had arisen on alien planets? * there are likely many more thousands of questions to ask. Feel free to think of your own! The only, and unfortunately bleak, real reason where Star Wars technology and science appears old is because the culture and society within the galaxy is stagnating. People are no longer asking questions. However, I do not think that this is possible, as **all** people, in **all** societies, need to have this malaise, and the likelihood of this is so very small. [Answer] # No, I don't think what you describe is people who have discovered all of science It honestly sounds like they are lazy and unmotivated, since they haven't reached far enough. Now, one could argue that "all of science" is an impossible goal. Maybe it is, maybe it isn't - I'm not going to make either way here. However, I want to describe my vision of people who are on their way to discovering all of it. They have mastered the manipulation of materials. They can rearrange atoms to make anything they want. They have mastered knowing their own mind, which I suppose will roughly translate to "psychology". They have build machines or *other beings* to also do thinking for them. Computers both electronic and biological. These could work on a scale we've never imagined - perhaps a Dyson sphere powers one of these. They've also mastered biology and can create new beings or reshape existing ones. In short, they can understand, manipulate and exploit most aspects of the universe they inhabit. Let's assume time travel is not possible, otherwise things will start to get messy. These beings have learned enough about their universe. They still need to know and discover *more*. So, they start making *new* universes. They have the knowledge, they have the means, they can lay down only *some* of the scientific laws they know, to observe how that will change *everything*. These universes could be like pocket dimensions, or some parallel one, or maybe even a very advanced simulation running on an unimaginable computer. Whatever the case, the advanced beings make and observe them. They can seed it with life, they can change how they work, they can destroy and recreate these universes at will. All in pursuit of attaining *more* knowledge, to understand *more* of science. They still haven't reached that final bit. So, *while in pursuit of all of science*, these beings are already *gods*. The gods of universes of their own creation. They can also significantly influence their own universe. What happens *beyond* that? They should become something even greater. They should, as they would be attaining even more understanding of everything, and through understanding the ability to control and manipulate it. [Answer] **Theoretically doable, as one day civilisation should reach brutal physical limits, not necessary achieving everything but achieving level where research projects no longer have any practical applications** Caveats: * A transhuman with a brain size below 1.5 kg, would not be a match for an AI running on a server farm. Even if AI is unable to enter technological singularity, it is still able to outperform humans. * Archaeology? Forgotten technologies?? Did people in your setting forget how to make back ups??? ;) * If one can not outcompete their rivals technologically, he should try to do it through better organisation. That's the only edge remaining (except of course brute numerical force). Possibly the most effective solution would be some bland authoritarian technocracy. ]
[Question] [ Bob the time traveler has a problem. He went to 75,000,000 BC to get some dinosaur eggs (don't ask) and his time machine re-combobulator broke and a big chunk is missing. Fortunately he can still make one jump forward in time, but he can't go as far as the XXIV century (his home era). Mostly he could land somewhere before the XX century. He needs [grade 5 titanium alloy](https://en.wikipedia.org/wiki/Titanium_alloy) to repair the re-combobulator. He just needs to smelt the alloy and his time machine nanites will do the rest. The further forward he jumps, the biggest the risk of vanishing in the timestream, so he **wants to jump the least possible** Consulting his encyclopedia of technology, he tried to figure out when is the earliest in history he can jump to where Titanium alloy grade 5 could be made with the technology available. He can set his arrival anywhere on Earth. He also has no diplomatic or monetary problems. He can mine the resources or has the raw ores in storage. P.S.: The story is just to illustrate the case in point. The question's title is all that matters. That is why there is no [time-travel](/questions/tagged/time-travel "show questions tagged 'time-travel'") in this question. [Answer] Depends on how good of a chemist your time traveler is. While the purification methods on many of the needed materials were not discovered until the 1900s a good chemist, craftsman, and historian could go back further to the discovery of the ores he needs. To make the alloy you will need Iron, Titanium, Vanadium, and Aluminum: Iron has been around for ~5000 years; so, this is the easy one. Titanium ore was first discovered in 1791 and could be purified via the Hunter process using chemicals that would be available by 1808 when Sir Humphry Davy learned to isolate pure calcium. Vanadinite, discovered in 1801 could also be purified by 1808 due to Sir Humphry Davy's discovery. Bauxite was discovered in 1821. All of the materials you would need for the Bayer process required to turn it into alumina already existed. The Hall-Héroult process required to turn alumina into aluminum requires strong electrical currents, but if you have a time machine, I suspect you've also got one hell of a power source your could tap into to pull electricity from. [EDIT] > > He can set his arrival anywhere on Earth. He also has no diplomatic or monetary problems. He can mine the resources or has the raw ores in storage. > > > Not sure if I just missed this before or if the question was revised. If the ore is not a problem, then all you are left needing are a good smelting facility and hydrochloric acid Hydrocloric Acid has been manufactured since about 800AD. It is made from Iron (II) sulfate (which was first used as an ink pigment sometime around 600BCE) and rock salt (which has been used since about 6000BCE). When you consider that these are both commonly minable substances, that means you could just add this to your grocery list of ores. There is also a good chance your timeship will have some extra batteries you could extract it from to save you some time if you are not needing a lot of titanium. This really just leaves the smelting furnace as your only big obstacle. Simple furnaces that you could probably make by hand and fuel with easily obtainable natural resources can only reach ~1300C, but you would not be able to get your iron pure enough with one. Finery forges are capable of fully melting iron allowing full separation of iron and slag, and could reach the temperatures required to process all of the materials needed to make your small amounts of your titanium alloy. These were first made sometime between 400-200BCE in ancient China. All ancient depictions I've seen of finery forges are pretty large; so, this may be the one thing you really need an existing civilization to be able to acquire. Incidentally, China is also rich in all of the ores that you need; so, you don't need to go very far for any of your materials. So, you could in theory go to China (~200BCE), find someone with a finery forge, and offer to exchange some modern metallurgy know how in exchange for use of their equipment. [Answer] There's some ambiguity in the question - the title says "has the feedstock" but doesn't indicate whether that's ore, refined metals, or "can get to places where the ore can be found". Assuming it's the first option, ore: # Probably Around 1900 [AlexP's comment](https://worldbuilding.stackexchange.com/questions/156360/when-is-the-earliest-in-earth-history-when-grade-5-titanium-alloy-could-be-made#comment489530_156360) is valid, but if your time traveller has Future Wikipedia downloaded into his phone-analogue, all of the necessary precursor chemicals and tools should be available at the turn of the last century - their application would just not have been discovered, so you'd have to [Scotty it up a bit](https://www.youtube.com/watch?v=xaVgRj2e5_s). The biggest hurdle would be vanadium. You'd need the pure metal to get proper grade 5 titanium, and the process for its purification wasn't developed until 1927. The chemicals and lab equipment involved *did* exist, though, so making a small quantity of the material, given all the necessary discoveries being known ahead of time, should be possible. Aluminum would be available (though expensive), and furnaces would be hot enough to make the alloy. *Edit, Addendum:* I don't know how much a few extra decades matters in a multi-million-year jump, but 1950 would be a *much* better bet which would make his job near-trivial. I suppose you can make the risk of being lost in the timestream asymptotic as he approaches, say, 2200, if you want to limit him, but assuming that's *not* the case, there'd be a lot less "explaining metallurgists' jobs to them" by just aiming a half-century further upstream. ]
[Question] [ I have a world where there are two types of beings. One type, let's call them X, exist in our "dimension," and the other, let's call them Y, exist in another "phase" or dimension. Only 10% of X beings have the ability to see Y beings. I need a technology that would make the Y beings visible to ALL X beings. Ie. a Y-being booster. Any ideas would be great, but this technology should be something a MacGuiver meets Einstein type genius with an Amazon account could build in his basement lab. Furthermore, I also need a technology to make them *invisible* to the 10% who can currently see them (because seeing them is a bit traumatic). Ie. a Y-being blocker. Now, I've developed a type of cloud chamber that makes them visible for scientific experiments because evil X beings are trying to kill the Y beings (using vapours that exist in both the X and Y's dimensions). But I need something that is portable that would either block or boost the visibility of the Y beings in a radius around you that would grow or shrink depending on the power source. This does not need to be 'real science;' it can be Star Trek or Star Gate pseudoscience, but if you have some actual links or science to back up your answer that would be awesome! I appreciate your help! [Answer] Since 10% of Xs can see the Ys, the question would be how do they see them. Given a "stretched science" framework, we have two clear possibilities - Biological differences (10% of Xs can see an extended range of electromagnetic frequencies beyond those of most Xs), and psychic/psionic/extrasensory abilities. **Extended Frequency sight** This option has a simple solutions for a technological civilization for both conditions. To make the Ys visible to all Xs, the Xs wear frequency shifting eyewear (such as infrared googles, but for whatever frequency is appropriate). To make the Ys invisible to the 10% of Xs, a pair of "dark glasses" that filter out the appropriate frequencies would work. **Psychic/Psionic/Extrasensory abilities** This is where things get fuzzy. You would have to define what these extra abilities are, how they work, and whether or not the appropriate forces involved can be detected by the society's standard science. For example, "Some Xs have an extra senory ability, used similarly to normal vision, that enables them to detect... um... neutrino scattering, something that Ys do naturally far more than any other substance known, because of their extra-dimensional capabilities.", or "Some Xs are naturally psychic in such a way that they can detect solids or semisolids near them without use of their other senses. No one really notices this sense in most cases (although some of the 10% are unusually good at dodging attacks from where they cannot see them coming), except the Ys are detectable this way. If someone becomes adept at using this sense, they can 'see' the Ys." Extending the science of these things will take extrapolation or hand-waving, but the mechanism should be either neutral to survival (just a random mutation that doesn't help or hinder a person's life expectancy), or somewhat beneficial (the ability to detect attacks from behind). [Answer] **Your Y creatures are very small.** The analogy is scabies mites. Measuring a fraction of a millimeter, most people cannot perceive them with the naked eye. With a magnifying glass or better, a microscope they are easy to see. Your sharp eyed people who can perceive the Y mites do indeed find them horrifying, because mites are crawling all over them looking for blood and tasty skin. These persons can be prevented from seeing the Y mites by giving them someone else's glasses together with a light sedative. Dimensions can be dimensions of scale. [Answer] ## The creatures are made of Dark Matter The true nature of dark matter remains unknown. What is known about it is that it does not interact with ordinary matter, except through gravity. These beings are only detectable as a spatial "ripple" that slightly distorts the objects they pass through, but not enough for an ordinary person to notice - unless they are trying to kill you, which they do by concentrating their mass into a single point, gravitationally compressing their target to death. Detection of the beings is not an either-or thing, but some people are more sensitive to slight gravitational anomalies than others, just like some people can detect changes in air pressure and predict the weather. A machine to detect the creatures simply needs to detect the ripples they make as they interact with normal space. Hiding the entities from those who can detect them is trickier, but perhaps technology that produces negative energy density could be used to counteract their effect, similar to "noise-canceling" headphones. This technology, if it is powerful enough, may be able to defend against their attack as well. [Answer] Y beings are ultraviolet colored. 10% of X people have has eye surgery for cataract, which replaces the lens of the eye. The trick is that our retinas are sensitive to UV light, but it gets blocked out by the cornea and lens of the eye. Some people who have had surgery for cataract can see UV - it depends only on the kind of artificial lens implanted into their eyes as replacements for the natural ones. Seriously! Regular X people would be able to film Y people by using some UV sensitive camera. Some cell phones will do the trick. So will a lot of handheld cameras. To make Y people invisible to those 10% of X people: use a device that shifts their frequency to higher than UV. Or some sunscreen-based transparent mist that absorbs UV. [Answer] 1. I’d suggest using something that detect infrared light. Even if the being can pass light around it’s body the infrared of the body has to go somewhere, especially on its feet’s or so. The result would be that the surrounding still heats up ..and that’s what you might see. The only case where that being doesn’t emit even body radiation is, if it is completely insulated. However that would ask for the being to heat up over time so that it has to become visible at times at least. 2. Otherwise could your detection work on the wavelength that your being perceive it’s surrounding ... it has to pass through to be absorbed hence it is not redirected most likely. Hence you should be able to see it on that wavelength. 3. You could use sound waves to detect waves like bats. Because it isn’t light it should make your beings visible. However in case those being use absorbent material the detection will be difficult. 4. If the detection doesn’t has to be movable you could measure the speed the light waves travel. A precise measurement would make changes due to bending light around the body visible. This however would be quite expensive. 5. Using a fog machine, water or powder making movements visible or something similar. You could use dehydration of the fog to produce a powder. The powder is put into a delivery charge that can dispense the material in a certain area. Maybe it can be burned to create a fog? Any counter measure would depend on the Methode of the cloaking. I assumed here that your beings are able to bend/redirect visible light around a physical present body. [Answer] **Ultrasonic Sensor** If you have a handheld device with an ultrasonic rangefinder, you can discover the invisible beings easily. Let's say it's attached to an LED display to give you a readout of distance to object in numbers (just to make it easy to use). If you're walking along, scanning in front of you, and the number suddenly jumps down while you're pointing at empty air, well buddy there's an invisible being in front of you. You don't even need to be a genius to assemble them, and they could be mass produced pretty easily. **10%** For the 10% who no longer wish to see the invisible beings, you should check out the hitchiker's guide to the galaxy. Zaphon Beeblebrox has a pair of sunglasses that can detect his stress level. When he gets too stressed out, the sunglasses turn completely opaque so that he cannot see the thing making him stressed. Boom, instant solution. Your 10% get scared and suddenly they're blinded, no flaws or setbacks imaginable with this scenario. [Answer] They could be detected by a " new " way of projecting Kirlian type images through to an eye piece setup in a google glasses kind of way, sent through in real time from a tiny built in Kirlian sensor. An experiment in visualizing electrical fields can lead to the discovery and the real time Kirlian imagery can show shadowy energy patterns that look like moving beings, without an object being there to generate the fields. Only ten percent of people can use them as they are science restricted to the public for what ever reason so only specialized people or very rich or both can get access to them. The science can get leaked online later as open source thus illuminating the unknowing ninety percent. The same experiments in visualizing electrical energy could also be the cause of the rip that allows the two dimensions to interact. Checkout the Kirlian imagery online currently its quite awe inspiring in its own right. [Answer] **Thiotimoline** In *The Micropsychiatric Applications of Thiotimoline*, Isaac Asimov describes a molecule called thiotimoline where the bonds around a carbon atom are so crowded, they are pushed into the past and future, so it takes a negative amount of time to dissolve. You can have two universes very close together through a fourth spatial dimension. A small amount of gravity can pass between the two, that they have starts and planets in parallel locations. Ordinarily matter can't pass between the two, but some complex organic molecules can have bonds that are so crowded that part of the molecule is pushed into the other universe, allowing them to interact. Around 10% of X beings have a mutation that creates these molecules in their eyes, allowing them to see into the other universe. Someone with a good knowledge of chemistry can synthesize such molecules - look at some YouTube chemistry videos to see the types of things that can be done in real life, it's pretty impressive. Alternatively, someone could extract the molecules from some insect or plant that for whatever reason has evolved the ability to sense the other dimension. Once you synthesize such molecules, you can use them to take photographs, or create digital cameras that can see into the other universe, or make a sheet that fluoresces when hit by visible light or infrared from the other universe. Or it could be distributed as a gas that fluoresces when it interacts with matter in the other universe. The Y beings can make themselves invisible to X beings by using a gas that will react with the parts of the molecules in their universe, breaking the cross-universe bonds. Something reactive like hydrogen should work. This has the side effect of rendering the X beings blind to the Y universe until their body rebuilds the cross-universe molecules. An X being could also take a drug that reacts with the molecules and breaks the bonds, if they want to make themselves blind to the Y universe. [Answer] I think it is more interesting if the invisible beings of your story were ghosts( if that is what you wanted us to understand). Ghosts are spirits, souls of dead people and animals and in the fantasy stories they livre in their own dimension bit they also can "walk" in the ordinary world and van see living people but cannot directly interact with them. If science someday proves that ghosts actually exists and there is life after death then science could create a machine that detect their energy which would be a special kind of energy with weird physics that is unknown to current science. Scientists would first need to fins out what kind of particle and energy they are made of and after that create an even more weird device that would enable people to see them. ]
[Question] [ An event has occurred several thousand kilometers from the surface of the Earth. Let's assume some sort of tear in the universe has appeared, from which extra-dimensional or exotic energy is pouring out. It has affected all wireless communications globally. 1. What alternative wireless communication form exists that might survive such disruption i.e. is less prone to interference than radio waves. Now I'm not quite certain what affect varying radio frequencies and wavelengths have on communication distance and resistance to interference, so: 2. Is there any science or science-adjacent justification for why some kinds of radio signals still work while others don't? 3. Alternatively, can providing more power to a radio transmission overcome such interference or not (and I know that's asking a lot because we don't know the precise nature of the interference, but could that make sense in some way)? 4. Finally, is there a possibility that wired communication might also be disrupted? [Answer] > > What alternative wireless communication form exists that might survive such disruption i.e. is less prone to interference than radio waves. > > > [Free-space optical communication](https://en.wikipedia.org/wiki/Free-space_optical_communication). Lasers and LEDs and photodiodes and so on. It can only be line of sight, and long range links are generally point-to-point, but it does exist and work right now. You couldn't keep your mobile phone in your pocket any more, but other than that these things could be replaced with new technologies and carry on working. Quite a lot of these devices are already in use and in production, though getting enough out to relink the radio-networked bits of world will probably take some time. Remember that communication with sattelites is only line-of-sight... launching a new optical-only satellite constellation would be a major undertaking, but it is just money and time. The technology is already available. > > Is there any science or science-adjacent justification for why some kinds of radio signals still work while others don't? > > > Shortwave [bounces off the ionosphere](https://en.wikipedia.org/wiki/Skywave). Microwaves can be scattered off the [troposphere](https://en.wikipedia.org/wiki/Tropospheric_scatter). VHF and the like is line of sight, mostly, but you can still do stuff like [bounce it off the moon](https://en.wikipedia.org/wiki/Earth%E2%80%93Moon%E2%80%93Earth_communication). These are all very, very difference mechanisms because the behaviour of radio changes drastically at different frequency ranges. One mechanism won't break them all, unless it is basically magic. A deliberately engineered attempt to break all of them could be done with *force majeure*. There are many techniques like [frequency hopping spread spectrum](https://en.wikipedia.org/wiki/Frequency-hopping_spread_spectrum), and clever communication protocols like [WSPR](https://en.wikipedia.org/wiki/WSPR_(amateur_radio_software)) which are highly resilient to noise and jamming. > > Alternatively, can providing more power to a radio transmission overcome such interference or not > > > Depends entirely on the nature of the interference. Handwave it as you wish. > > Finally, is there a possibility that wired communication might also be disrupted? > > > Doubtful, at best. Something like a [Carrington event](https://en.wikipedia.org/wiki/Solar_storm_of_1859) might affect *some* radio and *some* wired communications, and of course you're discussing something that may as well be magic, so you can feel free to define its scope. Fibre optic certainly not. [Answer] You need bullet proof, unassailable technology to solve this problem! # The Post No radio to be disrupted. No electricity or wires needed. Before there ever was radio based communications or even the telegram, there was the Post Office. [![enter image description here](https://i.stack.imgur.com/Sp7jz.jpg)](https://i.stack.imgur.com/Sp7jz.jpg) A letter requires no fancy equipment to make and no exotic energy defeating technology to deliver. [![enter image description here](https://i.stack.imgur.com/mc6U0.jpg)](https://i.stack.imgur.com/mc6U0.jpg) [Answer] The original form of radio — spark gap transmitters — using morse code is highly resistive to disruption. CW morse communications are the military’s fall back solution in the advent of nuclear war because standard AM/FM/PSK/FSK communications are likely to fail. Also time synchronous communications are very robust. Things like cells phones and towers use this technique. The synchronous nature of the encoding allows the receivers to accurately demodulate carriers] signals that are below the thermal noise of the universe. I am not suggesting our current cell system would keep working, just that a scheme using similar mathematics could be developed to permit wireless communications in the environment you are describing. It is imaginable that fiber optics systems would be unaffected by any interference you are describing and the majority of the internet is now running on a fiber backbone — as I understand it. If copper lines carrying analog signals are disrupted then it would seem that a similar digital comms system like DSL would continue working As observed before, lasers and photodetectors could be rigged to constructed to provide point to point communications. Line of Sight is straight forward. And, under special circumstances, with proper long IR wavelengths, long haul skip communication is possible — again using digital recovery techniques. [Answer] As a follow-on to elemtilas's answer, there's visual signalling. Semaphore telegraphs were very effective in their time; a heliograph or blinker light remains useful even today. Just like the post office (or its distributed version, the messenger / runner system), this requires relatively simple technology. As long as the two stations can see each other's signals -- which can be done at a longer distance than seeing the other *station* -- they can communicate with each other. ]
[Question] [ We're in a nearish-future metropolis and the secret police are starting to take control of the city. They have some new technology, including hoverbike-style vehicles (I imagine them as single-person vehicles), that stay above ground when on the move and can zip through the city streets. I guess I am thinking of something along the lines of what we see early in the (2009?) Star Trek movie, when a young Kirk is being chased by a policeman on some kind of hoverbike vehicle. Also the small vehicles used by the Jedi in AOTC when they chase Zam through Coruscant, they are high-flying but seem to be able to fly low too. Would it be possible to create a functioning version of this kind of vehicle, let's say in the next 40 years? I'm open to all ideas regarding how it might work. I'm not a scientist though I understand that magnetism only works if there is a magnet on the static surface (ie the road) too? I'd rather not have them kept up by huge cannons of water, and also would rather not have them use some form of energy or raw material that we haven't discovered yet. What are the other options? Gas propulsion? Could some kind of electromagnetism work? Quick edit: I've just thought about the big ships in The Matrix too, that have those giant electric-blue things around the outside of the hull. I have no idea how they operate but maybe something on a smaller scale could work? [Answer] Ironically enough, these kinds of vehicles are actually *less* likely today than they were in (say) the 1960s. The reason for that is the current focus on efficiency. When you get right down to it, anything that hovers has to constantly apply energy to maintaining a set distance from the ground. This is on top of any other energy that has to be applied to get the hovering vehicle to actually move. This is because of gravity; the Earth attracts all nearby smaller objects to itself and as such you need to counteract that force by turning real energy into potential energy (the energy that would be applied by the earth to a falling object) on a constant basis. The wheel on the other hand actually uses gravity to its advantage by using weight to press the wheel to the ground, causing tension which in turn causes friction, which (if stronger than the rotational energy applied to the wheel via the axle) causes lateral movement through rolling. This is why car tyres are made of rubber; it maximises the friction between the tyre and the road, making the lateral movement of the car the least resistant application of the energy. In other words, hover cars and bikes need to apply some of their energy constantly to fighting gravity; wheeled vehicles actually use gravity to apply their energy to lateral movement. Yes, these are simplifications of the physical laws, but they are functionally correct. In point of fact, we **do** have a vehicle that performs the way you describe and it's been in service for many decades; it's called a helicopter. We don't like it in sci-fi for a simple reason; the rotors are too big meaning it can't get in tight and do all those dog-fight scenes. Also, they can really suck at those tight fast banking turns and rolls and the like that we like to see on films. But, it's actually a good fit for the rules you've given, and the point of it is that if we *could* make the rotors safer, smaller and make the craft more agile, we already would have. So the answer is probably no. **But**, there is one technology that could make this issue go away; anti-gravity. Just like how in 1861 the Maxwell equations integrated electricity and magnetism into a single fundamental force and led to wholesale jumps in technical advancement that had not been possible before this, if we were to integrate gravity into EM as a fundamental force, and learn how to use EM energy to manipulate gravity directly, it could change the balance of energy use by allowing us to create localised fields of either counter-gravity or nullification fields of some kind. If you have that, all of a sudden you're not contsantly having to fight gravity, your vehicle sits inside a small bubble in which it just no longer exists. In such a situation, the only energy cost is moving the vehicle in 3 dimensions. Even just a localised effect (like the EM pads on the Matrix ships) could work insofar as they force a vehicle to hover by some form of gravitic repulsion. But, to do this right, you need gravity to be affectable via EM fields, and to do that we need to integrate the fundamental forces accordingly. The caveat on this is of course that the moment your nullgrav field fails, you fall to earth and go splat. But, this has been the case for planes and helicopters for over a century now so we know how to handle that kind of problem. In short though, if you're not happy with current helicopter design, then the integration of gravity into EM is the one defining piece of research you need to make such a device more energy efficient and easier to maintain / refuel in large quantities. [Answer] Police hover bikes already kind of exist: <https://www.youtube.com/watch?v=4dk-fiyJdvE>. If you want something a bit more high-tech feeling, you can replace those bulky fan blades with jet engines, but it's still something well within the limits of modern tech. So, the real constraint here is not "can we make hover bikes", but under what circumstances do they become worth their utility cost. Other answers have already addressed why they are not cost-effective in most situations; so, if you want to work them into your story, you need to put them into a place where living conditions are so dense that ground vehicles are an impractical first-response solution. In overcrowded urban settings, pedestrian foot-traffic can become so thick that cars have trouble being a viable means of transportation; so, such vehicles would be cheaper and more able to fit into tighter spaces than helicopters, but able to fly over a crowd or traffic jams to respond to an incent. [Answer] The problem here is not so much a technological one but a usability one. Today we can easily build hoverbikes (have a look on Youtube) that use jets or fans to keep the bike in the air. There are also bigger versions of that that can carry multiple people, they are called helicopters. The big problem why we don't use these things the way they are used in Star Wars is that they are hardly useful. Just compare a hoverbike to a regular bike. * The regular bike has a lot more traction, that means energy can be transferred much more efficiently. That means both acceleration, deceleration and manoeuvring can be done much more efficiently. Using the same amount of energy will give you a much better result in the comparatively low-speed (less than 300 km/h) chases you would be able to get in a city. * Because of the last point, hoverbikes would be much worse when it comes to taking sharp corners. * Hoverbikes need to spend a lot of energy just to stay afloat. * When flying close to the ground, there is something called ground effect, which does reduce the amount of energy necessary to hover by quite a bit, but it also creates a lot of random turbulence which makes flying close to the ground very hard and uncomfortable. * Hoverbikes become more efficient compared to the regular bike the faster they go. So on a long, straight stretch, the hoverbike could be faster than a regular bike, but only when they are not flying close to the ground. I am talking about anything >200 km/h. The higher in the sky it is the more efficient it will get. * Hoverbikes can also fly higher while a regular bike can only stick to the ground. This can be quite an advantage in a chase. TLDR: The technology for a hover vehicle is already here and has been for a while. But it is a very flawed concept that looks a lot cooler in movies than it is in reality. And it will stay like that because it is not a technological problem but a concept problem. [Answer] I like your magnetism idea. Why not they secretly built all static-magnet spread around the city, from tiny things like a signboard to the giant structure like a bridge, rooftop of a building. The technology core is an AI which calculates the static-magnet around the vehicle and manipulates the forces for the movements. ]
[Question] [ Magic works through transmutation circles infused with sigils that both manifest from a person's mind. The individual focuses their Anima, or life force, through these circles in order to create magical spells. Each sigil has Anima requirements, and Anima must run through them at a certain pace in order to function. A spell that has a total cost of 1000 can be done by a spellcaster born with the same amount of anima, but another individual with 200 anima would need 4 other spellcasters to help complete the spell. Different combinations will work as long as it adds up to 1000. This presents a number of problems for the latter group, as it comes with certain requirements that must be met. 1. Each spellcaster must perform the spell accurately and in sync with each other, or the spell won't work. This makes it more difficult to perform the more casters their are. 2. These casters must be connected to each other through an object made specifically for this purpose, which links the transmutation circles together to form one large circle. 3. Anima from the casters build up a lot of heat, which can be fatal to the participants. Therefore, this object that links them together must double as a heat sink, which absorbs the excess heat from the casters, similar to a running computer. This is the conundrum. A caster that has the exact amount or more of anima that the spell requires doesn't have to worry about heat exhaustion or burning out. However, multiple casters combining their anima to meet the requirements need a specialized heat sink to avoid burning to a crisp. Why would this be the case? [Answer] I'd go with a variation of [Brooks' Law](https://en.wikipedia.org/wiki/Brooks's_law) for this: > > adding human resources to a late software project makes it later > > > The point in Brooks' book on software project management is that keeping people synchronized with each other is hidden effort that becomes greater the more people are involved. By that logic, five casters of 200 don't *really* add up to 1000 because they spend a percentage on working together rather than casting, so to speak. You might go with a formula of, for example, `2% * #casters`. This is the strict interpretation of Brooks' law that replaces an individual's ability to work with their anima value. A looser interpretation might be that they can each contribute their full anima, but produce heat as a byproduct of the extra cooperation effort. [Answer] The heat is generated by magical turbulence tossing the energy away from the focus of the spell and into the ether as unproductive heat. A single skilled caster is able to predict turbulence for their own stream, but it is too chaotic to fully manage when multiple mages are involved. Typically, when focusing their anima through a transmutation circle the energy the caster is pumping follows a [laminar flow](https://en.wikipedia.org/wiki/Laminar_flow) pattern, nice and smooth with no friction or energy loss. However, when multiple casters all try to focus on a single circle, it's difficult if not impossible to predict exactly where each caster's magical flow is going to be at any given moment. Beams get crossed, magical flows turn into [turbulent](https://en.wikipedia.org/wiki/Eddy_(fluid_dynamics)) streams, and energy [eddies](https://en.wikipedia.org/wiki/Eddy_(fluid_dynamics)) cause the magic to be wasted as thermal energy. Skilled casters are able to contain this wasted energy and channel it into the heat sinks that connects them, whereas unskilled casters either must stop the spell when it gets too hot. [![enter image description here](https://i.stack.imgur.com/WIUdH.gif)](https://i.stack.imgur.com/WIUdH.gif) [Answer] **1) Friction:** Even synching up, their Anima is not perfectly compatible with each other. You can say, that the 1000 Anima spell doesn't require exactly 1000, when multicast but 1001, 1010, ... the extra Anima generates the heat. **2) Leakage:** Similar concept as with the friction, but this time the tool is the problem. It is imperfect, so some minor Anima is leaking out as heat. If the tool wouldn't handle it (as heat sink), the heat would travel back to the casters. 3) **In-built ventillator of the transmutation circle:** The circle function as a ventillator for a single caster (a single core). Multiple caster is like putting multiple cores under one ventillator which wasn't designed for that. It's not the amount of output Anime which generates the extra heat, but regardless of output, the Anima usage generates constant heat. In short, low Anima casters = old CPU's. Need more of them for the same task in same time as newer versions, but only have one cooler. If these don't work, please clarify why not and will try to come up with better ones. [Answer] Magic runs through things just like electricity. Different things have different measures of resistance or conductivity to mana (which you call anima). Mana is not electricity, though - mana resistance does not correlate with electric resistance. Turns out most humans conduct mana very well. The ones who do have some resistance to magic are those that have, well, a lot of resistance to mana. You know them, the kind that you can hardly ever mesmerise with a spell, and who won't be polymorphed no matter how hard you try. Ever noticed that after trying to bruteforce a lot of spells onto them hoping for a critical roll, you only give them a mild fever? That's why. Other materials may or may not conduct mana so well. When you link humans to cast magic, if you use a very conductive material the mana is distributed too fast. So the casters would need superhuman reflexes to coordinate the gestures, words and sygils. Using a material that is mana resistant means the mana flows slower, giving the time to react and coordinate so that the spell does not explode on their faces. But the greater the mana resistance, the more heat is dispersed as it flows through the material. [Answer] It arises from inconsistencies in individual transmutation circles. For instance, we can say that there is one "true" transmutation circle but that anything with a certain percent deviancy will still work fine. This results in every person who knows the spell casting it slightly differently. As a result, the source of magic has to make slight corrections to the group model as they try and combine their transmutation circles. These slight differences act as the "friction" creating heat. Thus, there is less waste heat when two people have a very similar mental transmutation circle. This would allow for highly trained groups to have very little waste heat while two random people would likely both die. ]
[Question] [ In my world, both lighter- and heavier-than-air craft exist and are rather useful devices. However, problems tend to occur when confronted with storms. Steering through a storm is not a problem in this question, but whether the craft survives it or not is an entirely different question. The three problems are as follows: * **Strong winds** put much stress on the craft * **Rain** may weaken the craft further * **Lightning** will have devastating effects **How can the craft be constructed to withstand a strong gale** ([Beaufort scale 9](https://en.wikipedia.org/wiki/Beaufort_scale#Modern_scale)) **without being fully cast in metal?** The craft in my world are primarily constructed of light wood and canvas, though other materials such as basic rubber, various metals and/or cellulose. Having the aircraft made with metal (as in more modern craft, although as I understand they are more aluminium and glass fibre than anything else) would likely increase the strength of the craft, especially against lightning, but at the cost of manoeuvrability and weight, making the craft unflyable with the weak motors of the time. [Answer] Simple version: you can't. *Modern* aircraft are prohibited by regulation from flying into thunderstorms, and that's with more than a century of real world experience. The only exception that's made that I'm aware of is military aircraft that fly through the eye wall of hurricanes to measure the barometric pressures and wind speeds at altitude -- important data for forecasting the intensity of the storm as it threatens surface ships (far sturdier than anything light enough to fly) and buildings (sturdier and heavier yet). Yet, the most intense hurricane core ever recorded has far less turbulence than a common thunderstorm, never mind the supercells that produce tornadoes. The only aircraft that might reasonably survive the turbulence inside a thunder storm cloud is one that's so small the wind can't produce an appreciable velocity shear across its length or span -- and that won't carry cargo or crew (we're talking model or drone size). Bottom line, if it's light enough to fly (even with modern engines) and big enough to carry useful crew, passenger, or cargo loads, you cannot make it storm proof by any means available to present-day technology. [Answer] **Climb higher.** The easiest (for certain values of 'easy') solution is to get above the weather. Fifty thousand feet is high enough to avoid most (but not quite all) weather. Hope the crew brought some oxygen. ]
[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/149054/edit). Closed 4 years ago. [Improve this question](/posts/149054/edit) **What would people do in 1860s railroad towns?** In a place similar to frontier America, it seems towns are built around very clear purposes. A majority of people would follow the town specific profession. Ranchers. Mine workers. Fishermen. Sawmill workers. What about railroad towns though? With no particular quality other than being a reloading point. A lot of people are gonna be railroad workers, warehousemen and tradesmen. That's for sure. However I feel like those jobs alone wouldn't provide enough purpose for the rest of the town - or work for the general population. What could make up the bulk of such a town? Will it just be lots of tiny business à la barber, carpenter, tailor, etc.? Or is there a profession the frontier common folk might default to? [Answer] At first the town would just be a place for railworkers, and the products they consume. So, saloon/hotel, general store, whorehouse. Maybe services related to the construction of track and operation of the trains, like loggers, and people to load and unload cargo. This logistic-based work, including warehouses and goods handling, are likely in the very beginning. There will likely always be some building construction work too. All these people require food, of course, so trappers and hunters will appear and start selling their catches. Assuming the land supports it, farming and ranching will also eventually appear and employ a lot of folk. A ranch is in many ways nearly a self-sufficient little village where all the "hands" are skilled in the basics of several professions. Having a few ranches will mean there are now enough customers to support dedicated, more skilled professionals such as wainwrights, tanners, rope makers and other craftsmen, horse care/farrier, trading post, church, sherrif, blacksmith, carpenter, tanner.. ie the very essential basics that the farms have had to do themselves up to now. The railroad would still be used for importing all the non-essential products and services at this point, but now the town can start to survive on its own, without being entirely dependant on the railroad. You will still see a focus to support services for the railroad, but economies slowly diversify as they grow. If the town gets bigger (limiting factors would include geography, climate, availability of attractive land, politics, railroad activity, security, etc), more luxury services like dedicated doctors, midwifes, moneylenders, undertakers, schoolhouse staff etc would start to become economically viable. More stores, more trade, as trade will always be strong due to the railroad. Tailored goods may still be imported, at least until the town grows big enough to support it economically. Barbers seem like a luxury reserved for very large and established towns, as they need a large minimum population. White collar workers would appear as the real money starts to flow, managing taxes, land use rights, settling legal disputes. Banks, jail, other entertainments, and specialists in different fields would be added later. [Answer] Railroad towns could have a lot of various trades going on, depending on different factors, including location. For example: If your railroad is near to a region with good agricultural resources, you'd probably have some farmers settling the outlying areas. These farmers would then depend on the town to ship their produce and supply their needs (medicine, cloth, maybe more seeds, etc). This would open avenues of trade for merchants supplying to the farmers. Then, if the merchants are successful, wholesalers might reach out to the merchants. So, with a resource-heavy town, I think you'd see a snowball effect of all kinds of trades popping up. You also have cool opportunities for conflict, as railroad towns could invite lawlessness and corruption. So, I'd just say, ask yourself about location first. Then about who is in charge of the railroad (as this person might influence the politics of the town), and so on. I think you have a fertile ground to grow your story! You might find this article helpful too: <https://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=2671&context=greatplainsquarterly> [Answer] When towns in this place and era were being planned, it was in conjunction with the railroad. A "railroad town" was not for railroad workers. They had their own camps for the few months they needed to be nearby, then they moved on. The town started with farmers. The bread and butter (literally!) of the town. The American government designated areas where they had taken land from those who already lived there and had treaties in place to enforce it (entire books have been written about the ethics and logistics of this). They chose the path of the railroad and decided on where towns would be. The main towns were on the railroad line and would have a station. So farmers (and/or ranchers, depending on the climate) came in, picked a plot, registered it with the local government office, and set up a claim with a shanty. This could be single men (and sometimes women), entire families, or the father of a family who would bring in the rest of the family shortly. None of these towns was ever just a junction point. They were all designed to be living breathing towns, with the advantage of being on a railroad line. Most people were farmers and they could sell excess crops, animals, etc. The railroad brought them seeds (they'd mostly save their own, but not always) and tools. Any resident could order from the [Sears Roebuck Co.](https://www.history.com/news/sears-catalog-houses-hubcaps) (though not until 1886, slightly after your time period). Tools of all sorts, household goods, even [ready-to-build houses](http://www.arts-crafts.com/archive/sears-roebuck.shtml) (plans starting in 1895, full kits 1908-1940). In those earlier years, the trains would bring lumber (if there wasn't a large local supply) and other building materials like nails, tools, glass. If a town had a natural resource (including from surrounding towns not on the train line), they could export it. **Most importantly, the train brought people.** New settlers, visitors, and it allowed townspeople to go off in search of seasonal work, visit family, attend specialty schools and so on. Traveling by covered wagon was grueling. Even on established trails, [10-20 miles a day was common](https://www.californiatrailcenter.org/frequently-asked-questions/). Solo travelers or coaches on (mostly) good roads, with just passengers and luggage, might cover more distance. [In one report from 1861](https://en.wikipedia.org/wiki/Stagecoach#United_States), an 80 mile trip took 17 hours. [1860-era trains](http://cs.trains.com/trn/f/111/p/51027/646681.aspx) on good tracks (near older, bigger, cities) could go 60 MPH, but 20 MPH was a lot more common out west. Trains could travel overnight and sleeping cars became available during this era too. So in 24 hours, one could go around 480 miles. Before the trains, there were still large towns out west but they might be more spread out. Train stations encouraged settlement. Only a few workers were needed for the actual trains. A station master and a couple employees. Train maintenance was done elsewhere, though there would be people and equipment for emergency train and track work. The post office is connected with the train, though existed without it too. Letters, packages, and notification of huge deliveries might come through there. The telegraph office is also connected with the train and did not exist before the train (the telegraph lines were along the train tracks and set up at the same time). This was the fastest method of communication. So add in a handful of employees for post and telegraph. More if you had home delivery. So imagine all the professions/industry of an 1860's town: * Farmer & seasonal farm hands * Grocer * Stores of various types (general goods, fabric, tools/supplies) * Lumberyard and builders/craftspeople * Schoolteachers * Sometimes a local industry like weaving or paper making. * Newspaper * Granary, flour mill * Silage and animal feed storage * Blacksmith * Medical (both for humans and animals, plus dentists and eye doctors) * Midwifery * Religious personnel (when the towns were set up, the major churches would assign pastors to towns and church-raising was one of the early tasks) * Bars and sometimes restaurants * Prostitution * Seamstresses/Tailors (especially in towns that had a lot of single men) * Home helpers (children who would help households out with childcare, cleaning, misc tasks, usually gender segregated) * Town administration (mayor, etc). * Law enforcement And so on. This is not meant to be an exhaustive list. I strongly suggest the excellent [Little House book series](http://littlehouseontheprairie.com/about-us/little-house-on-the-prairie-books/), written by Laura Ingalls Wilder, who lived through these very events as a child. The books are written for children and much of the "inappropriate" material is missing or hinted at. Plus Wilder's daughter edited the books to be more interesting to readers, so a few facts aren't quite right. But the basic history is sound and it's very illuminating. (Don't watch the TV show as a substitute, it is not historically accurate.) *By the Shores of Silver Lake* is the book with the town springing up around the train station, though trains also figure in later books and I would read them as well. ]
[Question] [ This is a follow-up question to this: [How can crones minimize risks of exposure in a human trafficking enterprise?](https://worldbuilding.stackexchange.com/questions/144147/how-can-crones-minimize-risks-of-exposure-in-a-human-trafficking-enterprise) Mana is life energy of the soul used in conducting spells. Crones are renegade witches that steal mana from other human beings through a ritual that ends up killing the subject. Through this method, the crone increases their internal supply and grows in strength. Unfortunately, this turns them into an addict. The more they use this method, the more they want. Now you would think that with a planet of billions, it would be easy to secure a victim to steal mana from. Poverty stricken neighborhoods and war torn places would be prime hunting grounds for people that won't be missed. However, the situation is more complicated. Stealing mana from any random individual results in a low payoff, as the crone cannot feed on most of that mana. Even a person born with an immense amount of mana would not be able to sustain a crone due to its minimal return. A seasoned witch, who has had training and practice in the use of mana, would be of much higher stock and value, a prime target for a crone. Although a witch may have a very low amount of mana available to feed off of, it would sustain a crone far better than a non-mage. These candidates are usually well-known and established individuals in their profession, or have received some form of recognition in the world. This makes them difficult to secure due to their public standing, and puts the crone in more danger due to their potential victim's ability to fight back with magic. Why would extracting mana from a magic user be more successful for a crone? [Answer] **Mana orifices are open in magic users.** As a muggle, I might be full of mana but I do nothing with it. It is stuck in there. I cannot get it out and nothing moves in. A magic user cultivates channels for smooth movement of mana into and out of the body. Depleting the body of mana via egress points and then repleting it through ingress points is key to the practice of magic. These access points might be placed in a mage's body via spells or rituals. They might be physical or intangible or both. They are kept fluid and open with practice and use. Those egress points are what the crone uses to drain mana from a magic user. Flow is already possible through these cultivated channels and the crone takes advantage of the egress points that the witch was using to do her magic. This is perfect for horrible crones because there is horrible rape connotation to the forcible hijacking of another human's bodily access points. [Answer] For the same reason you fill your car up at a gas station rather than an oil field. Sure, you could go out to an oil field with a drill, fill up some barrels, [process it to separate all of stuff you don't need](https://en.wikipedia.org/wiki/Oil_refinery#Major_products), and finally put the gasoline in your car and head off to work. Or, you can spend 5 minutes filling it up at a gas station. Mages have much more refined and usable mana than muggles and are thus better targets for the insatiable crones. In your other question you mentioned that people are born with a certain amount of mana and it must be refined with practice in order to do anything productive. Well, ripping unrefined mana out of a person doesn't magically refine it inside the crone, they still need to separate the wheat from the chaff. The crone must refine that stolen mana just like their original mana, and although they are better at doing so than the average muggle it still takes time and energy which lowers their mana profit margins. However, using a mage filled with already refined and concentrated mana makes that process much easier. Instead of scouring the body to soak up all the dispersed mana the crone can just rip the mana out in one go, and they've done the dark deed enough times that they know how to best use refined mana without much effort. [Answer] Building on the other answers... If everyone is born with mana, then it must serve a purpose beyond what mages use it for. Based on the fact that removing mana kills people (though that could also be the methods), it must have something to do with sustaining lifeforce. You say it's "life energy of the soul," which is similar. But draining mana could leave someone as a husk of a person. The fact that it kills them means it's required for life. It's likely that mana serves more complex purposes as well. Perhaps it is the "muse" that inspires an artist. The drive that gets an athlete into practice every day and sustains her/him during sport. Or the creativity of a writer spinning fanciful tales. Each person would use her/his mana in different ways. Whether it's to endure drudgery, to manage to keep going even under unbearable conditions, or even just to find joy and purpose in an otherwise mundane life. Mages would scoff at the idea that any use of mana aside from the high calling of witchcraft could change the mana in any meaningful way. But it does. Mana aligns itself within the person, so it can better serve its purpose. It alters it in a way we might describe as being on a molecular level, if it had molecules. When a crone rips the mana from a person s/he has 3 choices: 1. Take it from a fellow mage. The mana will not be right for the crone, because it is aligned to someone else, but most of it will be useable. This is why there are side effects to using it. 2. Take it from someone who has not yet altered their mana (a young child, for instance), but there are reasons this wouldn't be useable to a crone either. 3. Take it from an adult who isn't a mage. This person will have good mana, but it's strongly aligned to the person it is a part of. Because the person does not use it for magic, very little of the mana is something the crone can make use of. The risks of using a fellow mage are much higher, but the payoff is exponentially greater than it is with using a muggle. [Answer] It's not about the mana it's about the mystical structures built into it. Raw mana is like a forest, plentiful but hard to use. Part of being a witch is taking that forest, cutting it down and building nice things out of it. It's a long, difficult, painful process to take the very essence of your soul and who you are and forcing it into an artificial form. And that's when you are using your own soul, which you know intimately. Doing that with the energy of someone else's soul is like cutting down a forest and building a house while blindfolded. So much easier and less painful to just take the finished product. [Answer] Have the act of stealing mana be a discrete action, which takes effort and resources from the crone. Thus it's better to steal 100 mana from one person rather than 10 mana each from 10 people, because you only have to spend the energy to steal once in the former case, while you have to spend 10 times that to steal from 10 people. Make the rules be that stealing mana steals one *coherent* unit of mana. Think of it like chipping a diamond out of a rock -- you always get one diamond, because it's got one coherent crystaline structure. If it's not coherent, it has a fracture plane, breaks off, and you only get part of the diamond. Or think of it like slurping a piece of spaghetti. If the spaghetti was poorly made, it will have lumps that aren't homogeneous, and the spaghetti will break off when you try to slurp past the lump. An untrained person may have a large amount of mana, but it's not coherent. The crone would have to suck up a little, then go back and suck up a little more. They couldn't get all of it in one go because it isn't one amalgamated body of mana. (Try focusing on exactly one thing for more than 15 seconds... and you'll see what I mean about how we aren't always amalgamated -- we're fractured and easily distracted) A trained mage is going to have to have learned how to make their mana coherent in order to cast bigger spells. They'd probably leave it that way so that they can cast those spells on a whim, without having to prepare their mana for days. But it also leaves them vulnerable to one well-placed mana steal. This would also open the door for mages who intentionally train to have their mana broken into a small number of coherent elements, so that if the crone steals one of them, the others are still available to combat the crone with. ]
[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/142525/edit). Closed 4 years ago. [Improve this question](/posts/142525/edit) Backstory: One space-faring civilization detects evidence of intelligent/sapient life on another planet. They send emissaries. The people on the planet, a species of intelligent apex predators, promptly murder the delegates, take apart, analyze, and start producing crude copies of their ships, and begin prowling the universe as murderous space pirates hunting the other species for sport. In order to explain why a somewhat less technologically advanced species from a single planet can strike terror into the hearts of a more advanced, more populous people, said alien species has a rather impressive list of abilities, as follows. (I'm being quite detailed here so I can refer back to this post in any further questions about this species, rather than typing it out again, though most of it is pertinent to this question as well, so I would recommend reading it before answering. The specific question is in the last paragraph.) 1. Great physical prowess: they are extremely fast and strong (fast enough to catch an arrow or deflect bullets, but not the Flash. Strong enough to rip off your arms, but not Superman). Essentially, their skeletal and muscular structures are much stronger and more efficient than Human Joe's. 2. Enhanced senses: they have excellent senses of smell and hearing (they can track a person like a hunting dog if need be), their eyesight is approximately on par with your average human's, except their night vision, which is vastly superior. They also have the additional sense of heat detection. 3. Virtually impossible to kill: their bodies heal at an extraordinary rate. Wounds that would be fatal to Human Joe due to blood loss or irreparable damage aren't necessarily fatal to them. The best ways to kill them: Cut off the head (and make sure it stays off long enough for them to die), rapidly destroy such a large portion of the body that it is impossible to regenerate before death ensues, or continue damaging them continuously over a long period of time until they "run out of juice" and can no longer heal themselves. 4. Shapeshifting. The species can shapeshift, with some limitations. They have to turn into something alive (usually something real they have come into contact with before, though small details beyond what species they choose, such as bone structure or hair/fur color, they can generally use their imagination for as long as it doesn't break the functionality of their basic chosen template). They must stay within a certain margin of size in accordance with their original mass (they can make themselves bigger or smaller to a degree, but only have so much overall mass to stretch or condense). They cannot turn their bodies into non-organic tissue (aka no metal skin. Bone or scales, perhaps, but not metal). There are some materials inherent to the species' homeworld that are "compatible" with their shapeshifting, for instance, the hides of certain animals and the fibers of a certain plant. They use these to make clothing and can incorporate them into their bodies when shapeshifting if they desire. There is also a kind of metal that they can change the form of, but not to the extent they can the compatible organic materials. Aka, if you are wearing a leather coat and a metal sword, and turn into some kind of animal, the leather may become part of your animal body, but the metal may not. You can, however, change the sword's form into something more convenient for your shape, such as a metal plate on your back. This metal is very strong, very heavy (by Human Joe's standards), and very expensive due to a difficult mining and forging process. In addition, your ability to affect compatible materials is limited to things you are touching, and to a certain range away from yourself (say, about six inches). So, if you are holding your metal sword, you can reshape the handle and a few inches up the blade away from it, but nothing beyond this. If you are only 3 inches from your sword but not touching it, you cannot alter its form. The species are fearsome fighters, and in any kind of close quarters battle they can take out large numbers of Human Joe type people. Normal handheld projectile weapons aren't terribly effective against them, as they a) are difficult to hit b) bullets/small projectiles don't usually do enough damage to kill or greatly impair them and c) they tend to close range very rapidly and you only have so long to shoot at them until they are on top of you, especially in cramped quarters like spaceship corridors. I'm not going to go into detail of what kind of weapons people devise to use against them since that isn't the point of this post. I might make another post on this topic later. Here's the problem: none of their advantages are of much use in space piracy and murder until they are actually on board the other ship and can rampage to their hearts' desire. So, here is my question: You are a murderous, virtually unkillable alien species who wants to go slaughter all the people on another spaceship; given the above described abilities, how do you get off your pirate tub and over onto the poor hapless victim's ship? You don't target only unarmed ships, you welcome the challenge of attacking ships with weapons also, if you think you can get away with it. I almost didn't post this question for fear it was too subjective, but I think there are only so many possible answers that would actually practically work, since it isn't necessarily easy to board a spaceship against the owner's will, especially an armed one, and I'd like to know if there are any I've overlooked. There may be some options open to these aliens due to their survivability that aren't open to Human Joe. NOTE: Someone might bring this up, so I'm adding beforehand, they can indeed survive exposed in vacuum for a period of time, though probably not indefinitely. Edit: In response to some comments, yes, this species does indeed happily attack colonies and slaughter the people on them. I didn't mention it simply because it wasn't part of the issue at hand. They hunt the other intelligent species partly because it is more of a "challenge" than hunting animals, and the more challenging a target you successfully attack, the more "sporting" it is. Ships are harder to attack and locate, which presents a lovely little challenge to our predators. Some of you are also asking about infiltration or trickery. This is definitely possible, though limited by the fact that most of the predator race don't speak the other race's language. Also, some of these methods would be initially handy, but as the predators gain notoriety and essentially became like the boogeyman, those same methods would become less effective because the victim race would have become wise to them. Other methods, like the distress beacon trap mentioned in one of the comments, would probably still be useful, but harder to pull off. [Answer] From what you've given as abilities, I see two main, easy options: ## A) Mimetism One of your super-predator, (let's call him Bob) took time to study one of the poor human-type Joe (let's call him Joe) before brutally taking him/her/they apart. The next time they meet a Joeys spaceship, Bob goes in front of whatever communication device they have, shapeshift to look like Joe, and act like a *very-real-not-alien-Joe*™ until the other spaceship accept to dock with Bob's spaceship. Enter and murder at will. **Caveat:** Bob doesn't speak Joey's language? "Our mic is busted, as well as several other critical system, please send help" act could work. ## B) Ambush Along the lines of the precedent caveat, you can rely on the old sci-fi trope of the distress beacon1. 1. Salvage the distress beacon of a Joey's ship 2. Integrate it into your own ship 3. Trigger the distress signal and act dead. Shut down systems, fake minor damages and the like. 4. Wait for an helpless Joe to come and rescue you. The second he/she/they open the airlock, board the Joey's ship. Enter and murder at will. Alternatively, hide a few ships, wait for your prey to try to help the decoy, swarm the Joey's ship. Big(gish) space battles are cinematic. 1: I suppose that Joeys are advanced enough to have distress beacon, if they have spaceships. I also suppose Bobs are crafty, since they learned to make junk-spaceships from wreckage. They also have the nerve (or the stupidity?) to fly them and, IMO, that's extremely badass. If any Joe read that, I decline all responsibility for casualties on your side, you should be more careful [Answer] They developed a number of [boarding pods](https://tvtropes.org/pmwiki/pmwiki.php/Main/BoardingPod) and use them as the armaments of their ships. Self guided missiles with troops loaded inside that engage enemy ships and penetrate the hull to allow the predators to emerge. [Answer] Perhaps the most effective way would be **psychological warfare**. If they can bluff their way into letting the defending crew surrender, being taken captive or appear as a crew in need of emergency help they will be aboard the ship and may do as they will. The only truly safe way of entering a ship is through the **airlocks**, though it may be rather difficult to dock on a defending ship. Barring that, one may try to latch on and **pierce through the hull** of the ship, though this would require an unusual offensive structure as part of the ship, similar to a hollow needle with a seal around it. The needle to penetrate the hull and transfer the attackers, the seal to prevent pressure leakage. The closer the point of entry to control systems, the better. A fine sense of heat could be of use, since I would assume that, unless the ship is autonomous, the largest concentration of personnel would be found in the bridge. Keep in mind that, unless already inside the ship, your ***crew will only be able to detect radiated heat***, since the vacuum of space cannot transfer heat directly. It may be noted that larger ships would probably have ***breach containment systems*** similar to modern ships, where individual compartments may be isolated to prevent damage. These could also serve as a means of hindering the progression of the infiltrators. Other than that I would suggest **attacking colonies instead of ships**, for one since they could be easier to find and for the other since they needn't concern themselves with all this spacey stuff. I hope this serves as some form of inspiration. You may be able to gather more inspiration by doing some research on invasive species and parasites. [Answer] For this answer, I will assume that this species was not artificially created, whether that be by some Creator-deity or a hyper advanced civilization that likes to tinker with genetics. Instead, this answer operates under the assumption that the species evolved naturally, and that every trait it possesses is an evolutionary response to some evolutionary need. ## Here's what we know about these predators: * They are physically superior in every way * They are intelligent enough to recognize advanced technology for what it is and replicate it * They are highly capable shape-shifters * They are their planet's apex predator * They hunt for enjoyment as well as for food That is an impressive array of abilities! It tells us quite a bit about an individual's capabilities compared to that of the space-faring species you mentioned! But, it also tells us quite a bit about the kind of ecosystem in which they evolved in, as well as their probable hunting methods. So, what exactly do these traits tell us about this species? ## Their usual prey is probably more dangerous than any space-faring species they might encounter If these predators evolved to be as physically strong as durable as they are, then it suggests that their evolutionary path responded to a need for such strength, speed, and durability. This would imply that their prey, or other predators, are considerably more dangerous than those we are familiar with, or else the higher energy needs likely to accompany these traits would not be worth the trade-off. Meaning, whatever we can throw at them, they are likely accustomed to fighting things far more dangerous. Similarly, their obviously high intelligence would also have evolved as a response to an evolutionary need. Now, intelligence is very useful for planning, avoiding ambushes, using tools, and working as part of a societal group. However, high intelligence is also a heavy drain on the body's resources, as those processes actually require a lot of energy. This means that whatever benefit they gain must outweigh the physical penalties of intelligence. This will not be the case if they are already the biggest, the fastest, the strongest, or the most durable. If that were the case, they wouldn't have a need for intelligence, as it would not help them survive, meaning that there are almost certainly things physically more dangerous than they are, and that a high intelligence (in this case, capable of replicating alien technology) adds a lot to their chances at survival. All this is to say, they are probably more than capable of not just overpowering, but also outsmarting any space-faring species they come across. ## They are probably very convincing shapeshifters This is an incredibly unusual ability, and again, one that would likely only have evolved if it gave the species a significant edge. As with their physical and mental capabilities, this one suggests a need for advanced camouflage, and even imitation of other species. It is likely that there are other species on their world that live in communities, and that the predators gained a significant advantage from being able to impersonate and possibly infiltrate those communities. Now, these communities would be far more familiar with these predators than any space-faring civilization could be, and they will likely have developed effective techniques to find and expose impersonators as an evolutionary or societal response. This in turn would drive these predators to become even more effective at impersonating their prey. Coupled with the species' obviously high intellect, it's not too farfetched to think that they'd be capable of quickly learning to imitate, and even fluently speak, new languages. In fact, I'd consider it more likely than the case where they don't learn languages quickly, because speaking the local language is essential to effectively blending in with any community. With that in mind, and with the information they would probably learn just from inspecting those very first space vessels, it's possible that they can already speak whatever languages those vessels' crews could speak. In other words, infiltrating a space-faring society is just the next step up for them. ## They are social and highly inventive Building off of some earlier points, this species' high intelligence and apex predator status suggests not only that larger, more dangerous species exist, but that your predators *are still the superior predators.* Now, this is not a new concept to us. After all, *we* are Earth's apex predator. We are not faster, or stronger, or more durable than other species, and we would lose a fight against almost any other apex predator... except that we keep inventing new tools and we work together. We have always done so, and now we are *the* apex species of our planet. It is easy to imagine that your predator also developed their own tools, societies, and languages. In fact, this is actually necessary, or else they couldn't have possibly replicated the technology they found. So, this species is not just incredibly strong, and capable of planning, but they are capable of inventing and building their own tools, and they have developed their own societies. They are capable of working together and accomplishing things that no individual could accomplish on its own. ## Their prey has probably evolved defenses against them This species is their world's apex predator. This means that every species they prey upon almost certainly has some evolutionary advantage to help them evade this species, or else it would have likely been hunted to extinction. This in turn would drive the predators' evolution, fine-tuning their capabilities, their intellect, and their ability to deceive. Their prey is evolved specifically to defend itself from them, and by definition of being an apex predator, there is *nothing* on their world able to effectively hunt them. Compared to that, hunting a species that knows nothing of them and has not evolved any effective defenses against them will likely be easy by comparison, their only disadvantage being the technology gap. ## They like to challenge themselves As you mentioned, this species will be hunting vessels for the challenge rather than by necessity. A species does not hunt for sport or seek to challenge itself unless it is already doing well. And considering the monstrous hell-hole of a world that this species probably evolved on, the idea that they ever hunt for anything beyond necessity is terrifying. This means that, on a world where their prey is big enough, fast enough, durable enough, strong enough, and intelligent enough to require the traits this species possesses, they are skilled enough hunters to *hunt for fun!* ## So how might they hunt in space? They know their technology is (currently) inferior, so they know they probably can't outrun or overpower an enemy vessel, at least not in a straight-up fight. But they're used to that, so they know better than to try. Instead, they will probably fall back to the tactics that they developed through millennia of evolution on their home world. Use ambush tactics. Use numbers. But never, *ever* fight a fair fight! After all, no hunter has ever actually *wanted* a fair fight! ## Here's what I would do, if *I* were a murderous alien pirate Space is big. It is unbelievably, incomprehensibly big. This means that, unless I have technology capable of drawing a vessel to me and holding it there (unlikely), then I *have* to know where my prey will be. My technology is inferior, so I can't chase them down, outrun them, or overpower them. This means that I *cannot* let this be a fair fight! So what do I do? If they've already been infiltrated, then I will purchase information on my prey from one of our infiltrators. If that information cannot be found, then I will infiltrate them myself to get that information. If possible, I will even join the target's crew, at which point the hunt will practically be over. If I am able to infiltrate a crew, then all I have to do is wait until the ship is away from civilization, take out the crew (this is probably a smaller ship), and pilot it to a location I have prepared in advance. If none of that is possible, then I will identify a low-security supply station, research station, or anything else likely to be vulnerable. Then I will watch from a hidden location until I can catch a ship leaving atmosphere. As soon as something vulnerable leaves orbit, I'll intercept it before it picks up speed. This should allow the grapples, or equivalent, to latch the ships together and let me and my crew board. ## If I wanted bigger prey... Well that's a little bit tougher, but it follows much the same principle, the main difference being that *I'm bringing friends!* Now, I don't want to *destroy* their ship; I want to take home a trophy, and an upgrade! So, my ship will have a reinforced hull, with a heavy focus on survivability rather than firepower. As before, I'll have to locate an isolated target, and this one will probably *require* intel to succeed. So, no intel means no ambush. Now as before, I need to somehow surprise the target. If I have managed to get agents on board, then I can arrange for them to sabotage key systems at a time when they cannot quickly get help. Otherwise, I have to intercept them at their destination. Should I fail in that, either my prey will escape... or I will be destroyed. But then, what good is the hunt if there is no challenge? After that, it's just like with a smaller ship. Weather the incoming fire, attach to the ship, board it, and take it. To sew confusion, smaller vessels will launch and attach to other parts of the target. That way, they will kill too many of their own if they try to purge us, and we will be coming from too many directions for them to mount an effective defense. They may have reinforced their hulls or added redundant passages (which could be flooded with gas or fire), so our boarding tools will have to be able to puncture deep into the target. If their passages are short and convoluted, so much the better! This will allow my hunters to close the distance and tear them apart with their hands! But even so, each hunting party will be equipped with a shield behind which my hunters can find reprieve from incoming fire. This can be circumvented with heavy weapons, so my hunters will need ways to communicate with one another so we may surround and divide our enemies. The defenders may respond by attempting to seal us out of critical locations, or using bulkheads to isolate *our* hunters! Thus we will need to identify any control terminals or other access nodes that our hunters can use to disable such defenses! As with their heavy weapons, communication will be critical to countering this threat. With their defensive options accounted for, and with capable hunters more than able to improvise, my hunters will inevitably overwhelm their puny defences! Not only will we have numbers too great for them to overwhelm, but our superior physical and intellectual capabilities, coupled with our understanding of their technologies, will render their ship mine in a matter of minutes! With the hunt completed, I will either withdraw my hunters along with any captives and choice artifacts or data, or I will have the ship's critical sections sealed from the vacuum and leave with my trophy intact! And with this treasure trove of information and technology, it will only be a matter of time before I and my hunters can find a way to defeat even their strongest weapons, armor, and tactics! [Answer] Disable weapons and engines on the enemy ship and then grapple it. Then crawl along the grapple line and dig your way into the ship. If you can survive vacuum long enough, you can kill them all while they are fumbling for space suits. Otherwise, you need to drag portable airlocks with you along the grapple lines. Note that you don't have to disable engines if you out engine the target by a large fraction and your grapple lines are made out of some super material. I can't imagine that this is the case since second hand tech generally is not as good as the original. Especially since the originators will continue innovating while the marauders try to copy what they find. You also don't have to disable the weapons but that would make the whole process very exciting. [Answer] A couple of people mentioned this method already, but I would like to expand upon it as this has been an idea I had been thinking through for a while. To get aboard an enemies ship, I envisioned plowing through the hull. the boarding vessel would be equipped with a disposable "docking adapter" that the ship is attached to A 2 piece device. The first part is a spike made of some unbelievably hard material. the second is a ring with plasma fusers to melt the hull. The boarding vessel rams the target with great speed, piercing the hull. Enough so that the fusing ring is now in contact with the targets hull. The fusing ring is activated and literally melts the adapter into the victims hull. There are shaped charges detonated on the back side of the "spike" that blast chunks of this metal into the inner hull of the ship, blowing away any internal bulkheads that may get in the way and clearing the way for the boarding party to enter through the docking adapter. These warriors are in pressure suits in case the atmosphere of the entry location is not adequate. They are also equipped with plasma cutters and shaped charges to make t though any further security barriers. Upon completion of their hunting, they load back into their ship, detach from the docking adapter and simply just space anything left on the victim ship. This would be launched by the dozens from a larger "mothership" targeting larger victim ships. As the vessels are launched, the mothership pounds away the victim ship's defenses, producing weak spots in the hull, allowing the boarding vessels better chance at punching through the hull. Once one ship punches through, its all over. ]
[Question] [ The year was 2019. Somewhere in the middle of the North Atlantic Ocean (between Bermuda & Ponta Delgada) a new volcano erupted violently for a year. The volcano created a tiny island around 100 square km. A fishing ship discovered a new kind of fish coming out of underwater caves beneath the island. The fish have semi-translucent bodies which glow faintly in the dark. In its stomach random jewelry is visible. The jewelry ranges from a simple ruby ring to a diamond ring, gemstone rings, pearl necklaces..all kinds of normal accessories that you could buy with money nowadays. The only special thing about them is that the ring/band/chain is made of low enriched uranium. At first, people didn't know what it was. Then every country wanted a piece of it. Things got heated very quickly and nukes are ready to be launched. Which country is likely to have the biggest claim on the island? Providing nobody successfully claimed the island, what policy could be used to share the resources so that the world's powers are satisfied enough to not go to war? [Answer] > > Which country is likely to have the biggest claim on the island? > > > Whichever has the interest. For a historical reference, look at what happened with [Ferdinandea/Graham Island](https://en.wikipedia.org/wiki/Graham_Island_(Mediterranean_Sea)), a volcanic island appeared in the Mediterranean sea: > > When it last rose above sea level after erupting in 1831, a four-way dispute over its sovereignty began, which was still unresolved when it disappeared beneath the waves again in early 1832. > > > It was subject to a four-way dispute over its sovereignty, originally claimed for the United Kingdom and given the name Graham Island. The King of the Two Sicilies, Ferdinand II, after whom Sicilians named the island Ferdinandea, sent ships to the nascent island to claim it for the Bourbon crown. The French Navy also made a landing, and called the island Julia. Spain also declared its territorial ambitions. Each wanted the island for its useful position in the Mediterranean trade route (to England and France) and its close position to Spain and Italy. > > > Therefore any interested country can place a claim on the island. Then the usual options are either an armed confrontation or a diplomatic approach to solve the dispute. [Answer] No nation has any claim to that location. However it's on the opposite side of the World from China, Russia has no sphere of influence in the region. Closest powers are Britain (Bermuda, nuclear) and Portugal (Ponta Delgada, not nuclear [research only]). Which means the power in ultimate control of this apparent source of manufactured uranium products would be some sort of US special investigation team. There's no point having any pretensions about who is in charge when it comes to matters significant to NATO and nuclear materials. [Answer] This article sums up who gets an island quite well. <https://www.google.com/amp/s/www.vice.com/amp/en_au/article/exmjvz/how-to-claim-and-name-a-new-island-192> Basically if it is in a nations 12 mile zone it's theirs automatically and if it's within 200 miles they have a strong claim on it. As shown in the article some naval muscle flexing can extend the zone if noone pushes back. If the island truely is in international waters, whoever plants his flag there and can back up the claim with force gets it. There are no rules as far as I found out, just realpolitics. Now mind you that these kind of islands are a common occurrence, yet only one in ten survives for a significant time. So governments and even courious explorers aren't fast to claim these lands. I might even have a good location for your islands. I checked out Google Maps in the satellite mode and along the line you described there seems to be a group of underwater volcanos south of Newfoundland. (I could be wrong, wasn't able to find much else about those) But having one of those rise above the surface seems plausable. Thus considering the islands position I'm 90% certain that the island would be claimed by the USA. It is the worlds strongest naval power. Portugal, France, Britain, Canada and possibly Denmark and Iceland might claim it, but I only see that happening if 'murica isn' t interested for some reason. No matter who gets it I dont see how the issue is settled in a non civil way. All these nations are NATO and important trade partners. In fact Denmark and Canada had contested territory in the Arktic until quite recently, yet the "conflict" was based arround flag stealing and leaving whisky and a note claiming the island. No matter the resources, how are they worth a trade war or war with important partners? Now to the fishes and the jewelery. I don't intend to bash your idea, these are just some points you might wanna consider. Uranium is a quite poisonous heavy metal. In fact, if you where to consume a dose of Uranium salts, whose radiation would kill you, you wouldn't die by radiation. The hevy metal poisoning gets you first. Look up lead poisoning for details. How do the fishes survive the contact with the metal? And how do dead fishes don't poison the entire Atlantic? Concerning the valuables the quantity of these fishes is important. If they are rare, the resources would not be economically extractable and noone would fight for the island. If they are common they can ruin the market. You see, the high sale value of precious stones comes from their scarcity. (and market speculation and artificial scarcity induced by the traders, but that's a different story) If you now have this island where you can fish up metric tons of these scarce resources they are no longer scarce, so no longer as valuable. The current yearly gem production ranges from 30 kg (diamonds) to ca. 8000 t (amethysts). So if there are lots of your fishes they might upset the markets strongly. If the island truely is contested viciously a UN mandate or a joint US EU research initiative backed by those countries is consivable. This could be modeld after the Antarctica treaty, as the situation seems similar. A uninhabited island with ample resources. So you might get numerous sientific stations (joined or not) but no resource exploitation. [Answer] **The island would become a NATO protectorate, administered under the Antarctic Treaty System.** An island full of riches will turn into a free-for-all, with a great risk of damaging the resource. Access must be controlled to limit the possibility of damage, make sure benefit from resources is equitable, and especially to allow cool-blooded scientific study of the phenomenon without risk of looting or harm to the scientists by loot-seekers. Being as this island is in the Atlantic, it falls under the aegis of NATO and NATO ships would keep order. Operation Ocean Shield is something like this - here a cooperative (including non-Nato members) to suppress pirates and allow desired activities (mostly mercantile shipping). <https://en.wikipedia.org/wiki/Operation_Ocean_Shield> > > NATO's contribution to Operation Enduring Freedom – Horn of Africa > (OEF-HOA), an anti-piracy initiative in the Indian Ocean, Guardafui > Channel, Gulf of Aden and Arabian Sea. It follows the earlier > Operation Allied Protector. Naval operations began on 17 August 2009 > after being approved by the North Atlantic Council, the program was > terminated on 15 December 2016 by NATO. Operation Ocean Shield > focused on protecting the ships of Operation Allied Provider, which > transported relief supplies as part of the World Food Programme's > mission in the region. The initiative also helped strengthen the > navies and coast guards of regional states to assist in countering > pirate attacks. Additionally, China and South Korea sent warships to > participate in these activities. > > > In the interest of science and fairness, the island can be administered like Antarctica, through an extension of the [Antarctic Treaty System](https://en.wikipedia.org/wiki/Antarctic_Treaty_System). There is a clear analogy - like Antarctica this is a land without a native population but with natural resources at risk of being exploited for the benefit of one party or another. In addition to administration this administrative arm would distribute fish to zoos and jewelry to museums. Select pieces of jewelry would be sold, proceeds going to fund the administrative arm and standing NATO protection operation. [Answer] United States would have the strongest claim on it, but United Nations can suspend all claims and declare it a natural preserve, similar to [Antarctica](https://en.wikipedia.org/wiki/Antarctica#Politics). This land, undoubtedly, would attract a great interest. But unless it lies close to any nation's shore, any territorial claim would be weak. United States has the strongest navy, and is located reasonably close, but other nations, particularly Russia and China, should object to it, even if they don't have enough firepower to push US away from it. If it was before the mid-XX century, the strongest and closest navy would be the one and only deciding factor. But this is modern world, and politicians usually think twice and trice before starting a war, or even doing something that may lead to a war. If Russia and China's stance would be very combative, US may decide that the island does not worth the risk of going to war, and the matter should be settled diplomatically. Then the issue would be discussed at United Nations to fashion an agreement what the nations can, and can't do with this land. Likely such an agreement would prevent any nation from claiming this land as their own or introduce any military presence on or around the island. But the use of resources may be permitted, and some nations may have a bigger share of those resources. ]
[Question] [ The heretic Pharaoh Akhanaten and his wife Nefertiti have foolishly turned their backs on the Egyptian gods to embrace the monotheistic faith of Atenism. He has declared himself the son of Aten and has outlawed the worship of all other deities, bringing his population into heresy. Outraged at this betrayal, the gods have cursed all of humanity with what has come to be known as the undying plague, and closed off the afterlife to humans. From then on, all people who die will arise a few days later as a mindless zombie. Prevented from passing on to the next life, they suffer the eternal anguish of undeath and an intense craving for flesh. However, the heretic pharaoh has discovered a forgotten ritual that leads to true immortality. After a person dies, their body is embalmed and then mummified during this ritual, conducted by the priests of Aten. When the person inevitably rises, they retain their original faculties as when they were alive. The magic of the ritual sustains their bodies and prevents them from breaking down. The heretic pharaoh and Nefertiti themselves become liches through this ritual due to them having divine status. They commission for a magical wall to be built around Egypt, protecting it from the outside world. Current Egyptian society is as follows: 1. Liches- this encompasses the king and queen, their relatives, priests, and anyone they consider necessary to preserve the new faith and prove themselves useful. Their bodies represent perfect undeath and are eternal and never break down, requiring no form of mummification. 2. Mummies- these are the common citizens who are the followers of Atenism. They have proven themselves worthy in life and have been rewarded with a lower form of undeath. Although mummification sustains their bodies through magic, they suffer wear and tear and must be periodically repaired. 3. Living humans- these flesh and blood individuals go through life proving their worthiness to society. Now that the afterlife is barred to them, they must show their faithfulness and loyalty to be granted eternal life, or risk suffering the curse in death. 4. Zombies- these pitiless souls are made up of individuals who were not mummified and are forever cursed to walk the earth in agony. They suffer eternal hunger and waste away in a state between life and death, never to know peace for the rest of time. Mummification is expensive, the ancient ritual more so. This means that it would be primarily done to the most valuable people, with most others becoming zombies. For society to function, I need everyone to believe that everyone has an equal shot at an immortal afterlife, else they will rebel against the social hierarchy. How can I make this possible? [Answer] **Mummification is expensive.** Preventing zombies is easy - you burn the dead. But mummy making is really expensive and time consuming. And sometimes it doesn't work and you windup with a messed up mummy zombie thing. You are not going to make every random person into a mummy. You are going to mummify people who have a lot to offer the state and whose services are worth the great expense. Mummies will be indispensible thought leaders, religious leaders and aristocracy. The presence of the mummies in these roles mean that they will not be supplanted by up and coming humans who want to be the new religious leaders and new aristocracy, and so these humans don't get to be mummies. You have to really distinguish yourself to be a mummy. [Answer] **Burn *Everyone*** Your Pharaoh and his wife have undergone the rite to become immortal; to be frank, that's about as much 'stability' as you want in your sealed off Egypt. You really don't want other Immortals, Mummies, Zombies, or anything other than the living to walk the country with them, for several reasons; **1) Making Immortals elevates 'servants' to the same level as the Pharaoh** They may have been useful in *life*, but they wanted something from you; immortality. Once they have it, what hold do you have over them anymore. In time, their power and experience is going to make them think that they are your equal, and at the very least, rival. Not making immortals is the surest way to avoid this trap. **2) Leadership is about change (and more boring than you think)** Ultimately, unless they're very good leaders, the Pharaoh and his wife are going to end up seeing substantial change in their country; change for which they are going to be ill-equipped. The advent of technology, changing climate, changing world-views and fortunes among the populace; they'll all take their toll. Sure, the Pharaoh and survive by ruling with an immortally iron fist, but in the end he'll be a figurehead who the people pay tribute to but then turn to their own leaders, seeing him as largely irrelevant. Leaders need to be people who understand the times and the challenges of the future, and a ruling council of immortals are less likely to do that. **3) Equal chance is not the same as *good* chance** In the end, most people are going to see the writing on the wall, especially when your immortal ranks are already quite full and there's no room for more people at the 'top'. In such a case, you're actually going to see dramatic falls in birthrates because the people of the nation are not going to want to bring children into the world knowing that they'll become zombies. No-one would want that for their kids, and this is one of those cases where an afterlife is actually a *detriment* to people's spiritual life. So; what do you do? The best solution is to allow renewal by making cremation (something that would have been considered obscene in ancient Egypt) the rule of the day for the dead. Don't even tell them why - just make it a cultural practice. Then, you can actually use zombieism as a punishment; pretty much the reverse of ancient Egyptian belief. Here's how it works. Your average person on the street goes up, lives a good life, and is cremated within 3 days of death. This is seen as an honorable way to treat the body and it is done with all the necessary respect and reverence necessary to reflect this outcome. BUT - your traitors and heinous criminals; they're not cremated. They're left literally to rot in their cells as an example of what will happen if you're bad or don't toe the line. That's enough to scare the kiddies into line; 'Don't say that rude word or you'll end up being undead like your uncle Mustapha...' I know I'd stop saying that rude word, but I digress. The point is that your Pharaoh and his wife now have a life that power would normally give them, and more. They have eternally self sustaining bodies, a temple or palace of relative comfort; they don't really need to rule in order to preserve that. They're far better off setting themselves up as priest/priestess of this world, and letting it manage itself through modern, competent leadership that has grown up in the time that's being governed. In the interim, their immortality lends itself naturally to positions of faith, and they get called in to manage the funerary arrangements of all citizens (for obvious reasons) and as such, they can convince the world of whatever they want. In this case however, what they *don't* want to do is tell the punters the truth; give them some myth about the body needing to be burned to release the spirit from it so it is free to travel to the afterlife; otherwise, people will eventually lose hope and just stop having kids if they saw what their true fate was likely to be. That doesn't generate stability. Neither does the mummification. As such, they're far better served keeping it to themselves. [Answer] **Conquer the world!** The pharaohs of Egypt constantly struggled with the Assyrians, Babylonians , Hittites and other Empires for the dominance of the Near and Middle-east. In the reality, the frontline shifted somewhere between the Sinai and Damascus. But with the other powers being thrown into disarray by the zombie plaque, while Egypt has surplus undead men, they can march forth and bring much of Eurasia and Africa under the rule of the Pharaoh. As long as the source of balms are secured they are effectively unstoppable. (undead soldiers do not have to eat, I suppose) And the remaining population would receive the Egyptians as saviors as only they can give immortality instead of zombiness. [Answer] Have a Lottery Once per year, a tiny number will be conducted into immortality. The government may select a general or other hero of the people. The royal houses may each, of course, submit a name - no limitations: it may be it a family member, a faithful servant, a particularly valuable customer or friend. The priesthood of Aten may also put forth a small number of names : either clergy or lay people of tremendous merit. Finally, each village council of elders may submit one of their citizens in the lottery. Of course the game is rigged - or that's what detractors say. But there's no clear evidence. And any unequivocally proven fraud is - we're told - punished severely. [Answer] Unless I missed something, this is just a variant of "what if everybody was immortal" – there isn't a faction of humans and a faction of mummies, it's just that the former turns into the latter eventually. As such I don't think there would be a clash between the two groups, seeing as they're essentially the same population at different life stages. It would be like the young rebelling against the elderly. That leaves us with how to manage an ever-expending, immortal population, which is a theme that has already been well trodden elsewhere. Off the top of my mind: you'll probably need conquest to supply the expanding population with resources (although as noted, mummies shouldn't need food, so you need less land than if everyone was alive), and indeed the skill differential between people will keep increasing. You can compensate the latter point by making mummies less efficient (weaker, slower, less coordinated etc), so that what they have in knowledge, they lack in physical performance, for example. From that point on you can imagine all sorts of caste/class systems where the mummies are intellectuals and "flesh and blood humans" slaves, and so forth. [Answer] This seems like it's actually fairly easy to do. The one thing it requires is some form of media for communication. That can be as simple and low-tech as town criers, or as fancy as inventing the printing press for newspapers. The important part is that it reach everyone. Then you make sure that your mass media, whichever method you choose, is staffed and run primarily with mummies; probably with a lich or three in management. From there, you simply push the ideal of eternity, promise that anyone who works hard enough can get there. The "Egyptian Dream" if you will. The real key is to make sure to frame zombihood as a personal moral failing. With a bit of effort, you'll have the ordinary humans doing most of your work for you; suppressing dissent while they strive for something only a fraction of them will ever receive. [Answer] It feels like a lot of answer don't address your question, so here's my take : **Make people earn their embalming.** Being an immortal mummy is like our retirement with extras steps : you're not as fresh as you used to be and it costs quite a lot money. So let's do what we do, *make people save for it while they live*. If someone managed to accumulate sufficient money to be embalmed when they die then do it, no problem ! If they're so rich that they want to be embalmed young, why not ?! Capable people are a resource you wan't to keep fresh and the most powerful people in your civilization will support your religion, only the poorest won't like it. Make the amount needed sufficient for most of your people to strive toward it, even though a certain percentage won't ever achieve it. [Answer] > > They commission for a magical wall to be built around Egypt, > protecting it from the outside world. > > > This is both your problem and your solution. **Problem** If you have new births in a walled area and no-one dies permanently then very soon you have overpopulation. If you don't allow the living to have children then you will get unrest. **Solution** In one walled-off corner of the walled land is the City of Everlasting Peace. The walls are high and the guards powerful enough so no-one can enter except the priests and other privileged ones who live there. You tell the population that everyone who dies naturally and behaves as a good citizen can enter the City and will ascend to heaven - a world of peace and plenty. After a touching ceremony, the bodies are taken inside on a flower covered bier. Once inside with the doors closed, the deceased are projected over the wall by trebuchet and left to wander around outside for eternity. Anyone else who is surplus to requirements or criminal can simply be kidnapped and chucked over the wall without ceremony. [Answer] ## Be realistic: do different levels of embalming The rite might be expensive and the poorest of the poor will have to burn their dead to prevent making them zombies, but Herodot did tell us about mummification in the time just before the Ptolemaic Dynasty in his *[Account of Egypt](https://sourcebooks.fordham.edu/ancient/herodotus-mummies.asp)*: > > The mode of embalming, according to the most perfect process, is the following:- They take first a crooked piece of iron, and with it draw out the brain through the nostrils, thus getting rid of a portion, while the skull is cleared of the rest by rinsing with drugs; next they make a cut along the flank with a sharp Ethiopian stone, and take out the whole contents of the abdomen, which they then cleanse, washing it thoroughly with palm wine, and again frequently with an infusion of pounded aromatics. After this they fill the cavity with the purest bruised myrrh, with cassia, and every other sort of spicery except frankincense, and sew up the opening. Then the body is placed in natrum for seventy days, and covered entirely over. After the expiration of that space of time, which must not be exceeded, the body is washed, and wrapped round, from head to foot, with bandages of fine linen cloth, smeared over with gum, which is used generally by the Egyptians in the place of glue, and in this state it is given back to the relations, who enclose it in a wooden case which they have had made for the purpose, shaped into the figure of a man. Then fastening the case, they place it in a sepulchral chamber, upright against the wall. Such is the most costly way of embalming the dead. > > > If persons wish to avoid expense, and choose the second process, the following is the method pursued:- Syringes are filled with oil made from the cedar-tree, which is then, without any incision or disemboweling, injected into the abdomen. The passage by which it might be likely to return is stopped, and the body laid in natrum the prescribed number of days. At the end of the time the cedar-oil is allowed to make its escape; and such is its power that it brings with it the whole stomach and intestines in a liquid state. The natrum meanwhile has dissolved the flesh, and so nothing is left of the dead body but the skin and the bones. It is returned in this condition to the relatives, without any further trouble being bestowed upon it. > > > The third method of embalming, which is practised in the case of the poorer classes, is to clear out the intestines with a clyster, and let the body lie in natrum the seventy days, after which it is at once given to those who come to fetch it away. > > > As one sees clearly: There are cheap ways to cure a dead body to turn into a mummy. Reveal in this: The living can see the caste of their undead overlords from their looks alone! A crumpled mummy that was just cleaned out and has some light smell of jerky is of a lower caste than the skin on bones artisan, and then there are the well cared upper-class mummies, filled with linen and strongly perfumed, their dried skin glistening from the embalming oils. If you escape the poorest of the poor, you will at least be preserved and serve as a soldier for your god-king forever! ## Be safe: Only undead may be soldiers But why stop at class level embalming. Go on to make some jobs only available to some: Soldiers must be undead, farmers must be alive. Maybe even include a natural transition into it: Former farmers that die and can pay for the cheapest of the cheap embalming automatically are promoted to soldiers. The soldiers are then used to guard towns they are not from, so they show no scruples when riots come. ## Be safer: buy the dead that can't be burned Ane even the zombies fit the bill: If people are too poor to burn their dead, have the temples of Aten buy the dead for a few coin. Depending on demand of the King, these are then either mummified as soldiers, destroyed by burning, or they are thrown into well-crafted containment forts at the border to be unleashed on invading armies and guarded by dried out, fleshless second-class mummies. Make it an honor to serve as one. At some point, the border fortifications might have too much Zombies, at which point the Zombies are to be released to the outside of the wall, just as one would when an invasion nears: tunnels lead from inside of these pit-like fortifications to the outside of the wall, funneling Zombies to the wastes that other kings need to pass through to invade, turning them into a natural defense. This even could be advertised as redemption for bad lives: criminals are left to die in the desert forts and thrown into the pit with the other zombies after death, and then at some point released into the swarm that roams the wall to keep it clear from trespassers. ## Be Safest: KILL EVERYBODY But really, what reason is there to even keep living humans? The Pharaoh decrees to build huge embalming houses. Everybody that can't pay for their cheapest off the cheap embalming will work it off after their death in the gold and copper mines and armies. Then, round up city by city and deport them to the embalming halls, kill them by a ritualistic stab to the heart promising the eternal life and give them the embalming they are entitled to. Which means the cheapest of the cheap. [Congratulations Tomb King, you have risen!](https://tvtropes.org/pmwiki/pmwiki.php/Characters/WarhammerTombKings)TVTropes-Warning [Answer] A solution from the 'other side': If the (Egyptian) gods are punishing the people for forsaking the traditional religious rituals in their names, why not have Aten plead for some of the people? As an aspect of Ra, as the Sun Disc (I presume characteristics of Egyptian history and mythology that do not collide with your alterations still exist), **why not give Aten the right to plead for the lives of those who die during the day, or who die bathing in His rays of light?** [![Aten's rays distributing life](https://i.stack.imgur.com/lDuaD.jpg)](https://i.stack.imgur.com/lDuaD.jpg) [Answer] Two birds with one stone: organize huge **tournaments of people versus zombies**: Get rid of the overpopulation ('overzombulation'), and award those with the highest body-count with mummification. A third bird can be gaining territory: this horde of the toughest and strongest or nimblest men, Akhenaten's Immortal Army, can easily traverse the deserts surrounding Egypt and conquer neighboring peoples. (A fourth bird could be offering some form of *circenses* to the people watching the tournament, although the idea that your dead spouse could be in the undead throng might be unsettling.) ]
[Question] [ continuing from the question I had asked [yesterday](https://worldbuilding.stackexchange.com/questions/137747/is-it-plausible-for-a-being-to-possess-a-singular-halo-shaped-horn-while-othe), I have had another query come to mind. For my humanoid alien species to possess horns, it would surely put forward the risk of being the shortcut to a fatal neck injury, as they'd act as handlebars. These horns serve the purpose for additional hearing aid, disapating of excess heat and 'mating charms'. Is there a way without heavily altering the humanoid body shape or horns to result in a stronger neck structure to strengthen the neck against snapping by the literal handlebars? One idea I have had is to lower the heads of the species, or perhaps bringing them forward, to emulate a similar bodily structure of the Krogan from Mass Effect. [![enter image description here](https://i.stack.imgur.com/aC8iI.png)](https://i.stack.imgur.com/aC8iI.png) (Not my art, but a reference for the Krogan from Mass Effect) [Answer] Wonderful drawing! You do need a neck (spinal connection between the head and chest) if only to act as a channel for the spinal cord (I'm assuming the brain is in the head). So, IMO, all suggestions must protect the spinal cord. Because of this, IMO, you can't shape the bones to limit how much twisting they'll permit because a hard enough yank will turn those boney protrusions into quick paralyzation. * Thicker bones and stiffer cartilage. Pros: no significant change to the way the cretaure looks. Cons: makes it harder to move the head, which makes it harder to hear and see. That's a serious defensive drawback. * Shorter neck. Your drawing suggests you actually have a longer neck. Pros: thee's less to twist. Cons: you'll have to change your picture. * Seiously buff neck muscles. Pros: your efforts to twist his head off will probably result in an evil chuckle, when he flexes his muscles, the necklaces pop off, chicks dig him. Cons: There aren't many cons. You lose a bit of flexibility (can't rotate the head as far), but muscles are the first-level shock absorbers. You really don't want to trust to what comes after them. * Tendons between the skull and shoulders. This has all the benefits of reshaping the bones (which I said in paragraph #1 you shouldn't do) but not the drawbacks. Tendons will usually break before bones and cartilage, so they act as anchors. Cons: you can only turn your head so far. [Answer] **They are brittle and snap right off.** Most mammals with horns use them to fight conspecifics. They have to be durable enough to fight with. But secondary sex characteristics can be just for show, not for fighting. Your hornlike organs are for show, hearing and heat transfer. They don't need to be robust. Have them break off if stressed. There is not much to them and it is the matter of a week to grow another set. Although if they are for heat transfer they are probably full of blood. Breaking them off will be a mess, so go outside for that please. [Answer] Make the neck very short and squat, to give it enormous leverage advantage and resist bending(example elephant, or that Krogan of yours). **or** **Make the neck very long**, so the amount of bending/torsion per length is small enough to handle. The vast majority of animals use this solution. If your neck is 3 feet long then a 90 degree bend is still only 2.5 degrees of bend/twist per inch. This guy is doing 180 degrees (with 90 degree twist). [![enter image description here](https://i.stack.imgur.com/Ww9fb.jpg)](https://i.stack.imgur.com/Ww9fb.jpg) And here is a spectacular 270 degrees! [![enter image description here](https://i.stack.imgur.com/A9Z7s.jpg)](https://i.stack.imgur.com/A9Z7s.jpg) [Answer] **HORNS TOO BIG** The horns are so large and bulky that they restrict the range of motion of the neck. So even if your enemy grabs your horns and twists really hard, you just end up bashing your horns into your shoulder with a nasty bruise. [Answer] Instead of making it hard to break make it improbable(?) to break? The dinosaur Triceratops, oddly has a ball and socket joint in its neck, with beefed up muscles, making it very flexible, yet very strong at the same time. ]
[Question] [ This question is pretty straightforward: What is the minimum and maximum distance for a planet to be in the habitable zone of an average sized (not biggest, not smallest) Red Dwarf star? [Answer] There is no consensus now if such a thing as a habitable zone really truly exists around red dwarfs. # Flares Most red dwarfs flare, doubling their luminosity in a matter of minutes. This shifts the zone with optimal temperature very much, very fast, and the planet may be in it, and literally five minutes later be outside of it. Flares also tend do throw a lot of charged particles and do funny things with magnetic fields. If any planet around a red dwarf is able to keep an atmosphere is still an open debate. # Tidal lock Red dwarfs are cold. This means that "habitable zone" would make planets orbit their stars so close they would get tidally locked. A tidally locked planet would have its star-facing side above the temperatures needed for life as we know it, and its space-facing side much colder. This would create strong winds, except your planet does not have an atmosphere due to flares anyway. There are other minor issues, but these two points are the biggest, and easiest to explain reasons why talking about habitable zones around red dwarfs in general is moot. It is only reasonably possible to talk about habitability of a specific planet orbiting a specific, probably exceptional, non-flaring red dwarf. [Answer] Searching for circumstellar habitable zone lands you on this [wiki page](https://en.wikipedia.org/wiki/Circumstellar_habitable_zone) > > In astronomy and astrobiology, the circumstellar habitable zone (CHZ), or simply the habitable zone, is the range of orbits around a star within which a planetary surface can support liquid water given sufficient atmospheric pressure. The bounds of the CHZ are based on Earth's position in the Solar System and the amount of radiant energy it receives from the Sun. Due to the importance of liquid water to Earth's biosphere, the nature of the CHZ and the objects within it may be instrumental in determining the scope and distribution of Earth-like extraterrestrial life and intelligence. > > > The habitable zone is also called the Goldilocks zone, a metaphor of the children's fairy tale of "Goldilocks and the Three Bears", in which a little girl chooses from sets of three items, ignoring the ones that are too extreme (large or small, hot or cold, etc.), and settling on the one in the middle, which is "just right". > > > The same page also contains the following explicative picture: [![habitable zones vs star size](https://i.stack.imgur.com/Tpx28.jpg)](https://i.stack.imgur.com/Tpx28.jpg) [Image By Chester Harman CC BY-SA 4.0](https://commons.wikimedia.org/w/index.php?curid=64107813) The distance in astronomic units from a star with luminosity $L$ at which a planet could host life can be estimated according to the following relation: $d\_{AU}=\sqrt{L\_{star}/L\_{Sun}}$ Obviously the distance alone is not sufficient to have life. [Answer] > > What is the minimum and maximum distance for a planet to be in the > habitable zone of an average sized (not biggest, not smallest) Red > Dwarf star? > > > Flattening out all sudden magnetic and luminous flux variations (assuming the author has a way of achieving this by Sci-Fi means or just "Atypical Stability of the System"): * For the mean luminosity of an "[average sized red dwarf](https://en.wikipedia.org/wiki/Red_dwarf#Description_and_characteristics)" (in this case Median size - about 0.15 of the mass of the sun): * The habitable zone would extend between 0.04 and 0.1 astronomical units (Distance of Earth from Sun) with the closest to Earth's level of illuminance being at about 0.055 AUs. As you can square on this diagram: <http://sites.psu.edu/ceh5286/wp-content/uploads/sites/4579/2014/04/ndistance_HZ_09022014.jpg> (The image is free to use but too massive to upload to this site.) ]
[Question] [ The Eldar are a psychic species with a similar body design to humanity within a galaxy-wide empire. They are far more advanced than other races, technologically and philosophically. Eldar have a strange way of reproducing, which requires multiple inseminations in order for conception to happen. A male must add his genetic material at specified intervals throughout the year to the developing child. Genetic material could come from a single male or various ones with no connection to each other. This allows the female to psychically screen and edit the genes she has been given, keeping the good ones and disregarding the rest. The resultant offspring is a hodgepodge of various genes from different parents. The reason for this is because the galaxy is made more dangerous by the effects of the warp. This parallel universe is the sum of all emotions taken to the extreme, and filled witch creatures called daemons. This realm is currently bleeding into reality, and is a very corrupting force that causes mutations in anything it touches. Mutations may immediately show up in a individual, or can hide in their genetic code to affect future generations. This form of reproducing is meant to protect the Eldar as a species and prevent them from introducing infected and chaotic genes into their makeup. How would a species evolve to reproduce in this way? [Answer] All the Eldar have personal immortality and a stake in the shared consciousness of the Eldar species. Their population is maintained at a stable and optimal level according to their science and their traditions. Any time the sad occasion arises that misadventure removes a body/consciousness from the group, it is only fitting that when the shared consciousness detects a suitably advanced vessle for replacement that the mother containing it will be sanctioned to go ahead and prompt the foetus to grow. Occasionally this must be done on a large scale, as not all catastrophic gamma ray events in a galaxy are predictable, and adjustments must be made. At the moment of birth, a convulsion passes through the shared psychic link, churning all the shared memories of the Eldar-who-passed and thrusting them directly into the consciousness of the newley emerging baby. It contains the seed of it's own being, consciousness and it's own DNA. How else could order and ballance in the galaxy be maintained? That which was gone is reborn, what was lost is found, all is right. [Answer] Females don't produce eggs. They just provide the womb. Multiple gametes from multiple males fuse nuclei and then undergo meiosis, on multiple cycles. They then form colonies which are fully grown adult beings in the alien's [anamorph](https://en.wikipedia.org/wiki/Teleomorph,_anamorph_and_holomorph) stage in their life cycle. Each colony then produces a single diploid egg and dies. The eggs attach to the wall of the womb and are born as children. The children eventually grow to be adult aliens in the teleomorph stage of their life cycle. Having multiple males impregnate the female is a way to ensure maximum genetic variability. Finally, the gene editing is done by the anamorph colonies in the female womb. The colonies fight each other and the losers die without leaving an egg behind. This fight does a darwinian selection of genes. [Answer] The simplest answer is the one humans already have: # You don't know exactly when you're most fertile Women typically release one egg at a time. That egg has to travel down a tube to the uterus. That trip is the prime time for insemination to occur. While some women have an indicator that ovulation has happened, most do not. Moreover, the fertility cycle of some women is not regular (ovaries don't know they have a 28-day average). They only see the after-effects of not having become pregnant. As such, a human woman may need multiple insemination events before she becomes pregnant. The advantage to this is it keeps interested men near her (and thus more likely to help her through the pregnancy and child-rearing). Many animals, by contrast, typically mate only at peak times and the female is left to protect and rear young ones by herself. [Answer] The ability to screen, by choice, certain genes would provide a strong pressure to mate with as many potential good partners as possible. As soon as that trait has evolved it’s a short hop to the mother’s body refusing to pass gestational milestones without additional material to ‘choose’ from (even if it’s from the same father, the body doesn’t know that). As for evolving the ability to screen for gene compatibility, the obvious reason for wanting that is it lets potential mothers consciously pick and choose what genes they want, which could (depending on how well the mothers choose) confer significant evolutionary benefit. If you assume your mothers are capable of choosing appropriate sets of genes to achieve their desired effects (which is very, *very* much a nontrivial problem), then the survival rates of their offspring will be higher. Mothers who get more potential genes to choose from can maximise this, thus some women evolve to go into ‘heat’ and be receptive to new material often. If they don’t get it their body assumes the child will be born defective and re-absorbs the nutrients (much like rabbits in overpopulated warrens). Eventually only females who mate multiple times exist, and the ones who can mate just once disappear as they keep on wasting valuable energy on children with defects, severe or otherwise. [Answer] This mechanism appears to be VERY detrimental to species survival. Over millennia, these species would be at a clear disadvantage against their single-insemination peers. So, to make it at least somewhat practical, we need two things - Eldars must be very communal and very sexually active. This way, it doesn't matter if female would miss her second or third encounter with the male, or if the original male would die - there would always be an avilable "contingency". ]
[Question] [ I know a similar question was asked whether gas masks could be used to survive in space but it didn't quite focus on the parts I'm interested in. I'm building a world in which space travel is regular i.e. trips between a day to a couple of years, people living on ships permanently and city-sized space stations/ships. I don't think people would want to wear space suits their whole life and people would prefer to risk the danger of not wearing one for many reasons like practicality and because fashion(people still ride bikes without helmets). However, there would still be a risk of decompression so I was thinking as a possible compromise that some kind of base layer could be worn that would provide some protection. I was thinking of a two piece suit, trousers and top, worn as a base layer, that weren't necessarily air tight (I hear skin is fairly airtight) but would when exposed to vacuum constrict to provide even pressure around the body (maybe there would have to at least be air tight underwear to seal that area). Then in the event of an emergency that leads to a loss of pressure a person could put on a nearby face mask (would have to be strapped on tight) plus maybe gloves and ear protection. The purpose of this system isn't eva. Its so that a person has time to get themselves to safety or to give someone else time to rescue them. The closest parallel I can draw is an emergency gas mask I was provided at work which would only last about 15 minutes but could easily be worn on a shoulder strap while working unlike carrying full scuba gear all the time. (thinking about it something like that could be used for the face mask) The questions are 1. how would the suit work i.e materials, method of constriction. 2. Are there any improvements you can think of or redesign considering that it still needs to allow clothes to be worn over the top 3. how long can a person A)survive and B)stay conscious and mobile while wearing this type of protection considering if everything works out all the main holes should be sealed and an even pressure of one earth atmosphere from the neck down and on the face and ignoring air supply. [Answer] For the purposes of my answer I'm going to assume that this 'suit' only needs to protect you for a short time pending rescue and doesn't ask you to actually do anything to assist with that rescue, then an emergency space*pod* is your answer. Two pieces, each with a sealing ring and basically a spaceproof sack of foldable material up against the ring that allows you to put your feet in one, pull the other over you and seal from the inside. This would be wearable as a form of light backpack, and would only take around 30 secs to put on after proper drilling. At the first sign of trouble people start putting it on, and by the time real trouble hits they're fine. You could even put a small CO2 scrubber in it so you could last a little longer in it waiting for rescue. It would look like a small chrysalis and would render the occupant completely unable to assist you in his or her rescue, but it would be a way to stay safe over a short term period [Answer] What you might want is a [space activity suit](https://en.wikipedia.org/wiki/Space_activity_suit), a type of spacesuit designed to be low-profile, non-pressurized, and flexible. The basic principle is essentially as you describe it; it provides pressure on the skin to counteract the vacuum environment. Along with a separate air supply, it is in theory capable of sustaining a human for as long as they feel like it. The current state of the art is the MIT Bio-Suit, which consists of a single layer of, basically, spandex. (It's still in the experimental stages, so tests of different materials are ongoing.) Cords embedded in the material provide the necessary tension. The suit is custom-fitted to each wearer to provide the greatest possible mobility. The current design calls for a separate, pressurized helmet, boots, and gloves. You could probably skimp on the gloves if you were okay with stiff mittens; the main problem there is getting the tension elements to work properly around really small joints. Unlike what you were envisioning, the result is a single-piece, skin-tight bodysuit. You could wear normal clothes overtop it. You'd probably *want* to, unless going to work in your long underwear appeals to you. The helmet, gloves, and boots could be kept nearby and donned in the event of an accident, or you might put them on just in case before a potential hazard like a ship docking. As long as you're inside and otherwise protected, you should be able to stay in the suit as long as your air supply holds out. (Or until you really need to use the restroom.) It lacks much in the way of thermal protection, so if you were thrown out into space in direct sunlight, you would be in danger of overheating. You also might want to make a provision for tethering, lest you drift away from the habitat. The downside is, as mentioned, each suit has to be manufactured specifically for its user, so they're rather expensive and can't be provided for e.g. visitors. The upside is that the person in the suit is still active and has almost full mobility, leaving that much less for your first responders to worry about. [Answer] Don't have it be a space suit. Instead, make it a [Life Support Ball](http://www.astronautix.com/r/rescueball.html). Which is essentially I small inflatable sphere, with basic life support, to shove the person in. If they need to be able to manipulate anything, give a set of gloves or arms (these can pull double duty by allowing the person to move around) The bonus is that it allows for very little necessary training so it's perfect for civilian use! [Answer] People on the International Space Station today wear different things for different activities. They have one pressure suit they wear on the rocket from Earth, in case of emergency loss of air. This suit plugs in to the ship to get air and cooling in normal use, and has a small air supply for emergencies. It is not used to go outside the ship in space. In your future space society, people might only wear suits like this when they're on a ship that's currently doing something dangerous like lift-off, docking or re-entry. Or if they work in an airlock but don't go outside. ISS astronauts have another, bulkier suit for when they need to step outside the station. This suit has more air and more heat management features, and is more resistant to damage, and is suitable for working in vacuum in full sunlight for hours. And finally, when they're doing normal things inside the station, ISS astronauts just wear normal pants and Tshirts. Much like how sailors in a submarine don't wear SCUBA gear all the time. If a section of the station starts to leak air, they may just leave the damaged area and close it off before all the air escapes. That doesn't work in the tiny cabin of the ship that brought them from Earth, because they have less air and nowhere to go. The bigger your space station is, the less terrifying a small air leak is (at least to anyone not standing next to the hole in the hull!). ]
[Question] [ Aliens are very rarely portrayed as being furry, at least in proper xenobiology worldbuilding. They're virtually never depicted with feathers, and only sometimes with scales. Currently, there are three known integument structures which endothermic animals are known to use or have used; hair (in mammals and some other therapsids), feathers (in dinosaurs) and pycnofibers (in various archosaurs). Cicadas are also endothermic, and they insulate themselves with setae, but I guess that falls under the hair category. Scaly dinosaurs are thought to have used scales to trap heat, but that's not exactly confirmed. There are endothermic animals which have no hair, feathers or any kind of filamentous integument - such as cetaceans, tuna, and mosasaurs, but they're all aquatic, and since heat works slightly differently in water, I'm going to leave that aside for now. Moving onto hypothetical forms of thermoregulation, I could see three-layered exoskeletons (refrigerated by tracheae), skin folds, air-filled shells, and radiators such as dewlaps working, but, here is my rather difficult question; **Could a land animal with naked skin keep warm and cool down by its own means *without* radiators?** Perhaps insulation with fat and fat alone would work, but how would it cool down without skin folds or heat radiators? Would sweating work, or would it be too water-wasting? **Edit:** For further clarification; fire, clothing, frequent bathing, and only inhabiting warm areas are also not allowed. [Answer] So several person have mentioned the obvious fact that members of *Homo sapens*, and perhaps members of other closely related species, have been mostly hairless for hundreds of thousands of yeas at least. But they have omitted mentioning that members of some endothermic land dwelling species have also lost so much of their hair that it plays no role in temperature regulation. Species of elephants, rhinos, and hippos that dwell in tropical regions have lost so much of their hair that what is left has no ability to help regulate temperature. Note that some related species that lived in temperate or arctic regions retained dense coats of fur, like the wooly rhino and the wooly mammoth. It is certainly possible that if the tropics of a planet are warm enough, mammal equivalents a lot smaller than hippos, rhinos, and elephants might also lose their hair equivalents. [Answer] While the answer "humans have no hair either" seems to be a common thread, I suspect the OP is really asking for ways a creature could do thermoregulation without external surfaces: > > Could a land animal with naked skin keep warm and cool down by its own means without radiators? Perhaps insulation with fat and fat alone would work, but how would it cool down without skin folds or heat radiators? Would sweating work, or would it be too water-wasting? > > > Elephants use their ears as external radiators, so that is out. Although this may not fully satisfy the OP's intent, I would suggest that the way birds breath is a good way to fulfill the requirement. Birds have very complex lungs, and their body is filled with air sacks that serve to both lighten the bird's skeleton and increase the surface areas of the lungs to facilitate the most efficient air exchange. [![enter image description here](https://i.stack.imgur.com/ANjRf.png)](https://i.stack.imgur.com/ANjRf.png) *Sample Avian respiratory system* This massive surface area is also filled with a network fo capillaries, providing a huge surface area for heat transfer to occur as well. The birds effectively carry their radiators internally. Now in order to make this work more closely to the OP's question, the creature may evolve a more granular control of the mechanism. During cool days or when activity is limited, the creature can regulate the flow of blood to the air sacks, or there may even be sphincters or valves to limit the amount of airflow in and out of the air sacks. Warming is a different matter. In an endotherm, the issue is heat being generated from within, and in the cold, you either eat more calories to ramp up the metabolism, or shut down and hibernate. If the climate is very extreme, the creature might evolve a large and elaborate sinus system to pre-warm and moisten the air before it is brought into the lungs. Although unlikely, it may be possible to have "air to air" heat exchangers in the form of galleries inside the sinuses where warm exhaled air is used to prewarm inhaled breaths. The animal may have a large protruding nose, or perhaps a crest like some forms of Hadrosaurids for air to flow through while being conditioned. [![enter image description here](https://i.stack.imgur.com/IPmoq.jpg)](https://i.stack.imgur.com/IPmoq.jpg) *Hadrosaurid skulls: two species of Parasaurolophus* So if we take the OP's meaning to have a hairless animal with no visible or external radiating surfaces, then the trick is to expand the lungs and respiratory system to take the role instead. [Answer] > > There are endothermic animals which have no hair, feathers or any kind of filamentous integument - such as cetaceans, tuna, and mosasaurs, but they're all aquatic, and since heat works slightly differently in water, I'm going to leave that aside for now. Moving onto hypothetical forms of thermoregulation, I could see three-layered exoskeletons (refrigerated by tracheae), skin folds, air-filled shells, and radiators such as dewlaps working, but, here is my rather difficult question; > > > Could a land animal with naked skin keep warm and cool down by its own means without radiators? > > > Look in the mirror for your answer. Or at a picture of Dwayne "The Rock" Johnson. No hair, and he survives just fine. **You** don't have much hair, and you survive just fine, too. In fact, all humans -- manifestly land animals -- are pretty darned hairless, and we survive just fine. [![enter image description here](https://i.stack.imgur.com/cr7Dc.jpg)](https://i.stack.imgur.com/cr7Dc.jpg) And for those of you who think that humans *require* clothes, fire and other technologies to keep their body temperatures regulated... tribesmen from Papua New Guinea. [![enter image description here](https://i.stack.imgur.com/xrH7o.jpg)](https://i.stack.imgur.com/xrH7o.jpg) [Answer] Humans have evolved to become increasingly hairless due to the fact that technological advances mean that we no longer need it. If we are discovering other species of aliens, then they are likely sufficiently technologically advanced that they have no need for hair or feathers to regulate temperature. ]
[Question] [ So there's this guy called Joel who suffers from a case of bad luck. You see, Joel was just minding his own business (in a war zone) when a grenade decided to introduce itself to his face (we all have been there). So Joel's face was cut to ribbons; he suffered major damage to the face, neck and lost both eyes. A black site operative was in the area collecting (unwilling) test subjects for some cybernetic experiments and chanced upon him. So he took Joel back with him to turn him into a mindless killer cyborg (still better than the health care). So the problem is: I have no idea how they would install a Bionic Eye. It just seems much harder than, say, a hand or leg. In fact, check out [my question about a cybernetic arm](https://worldbuilding.stackexchange.com/questions/102273/biological-cybernetics-for-human-prosthetics) I did a while ago: same story, different character. I'm just saying: I know how the basics work, but haven't figured out how they would do it with the eyes. I think it would be very different from, say, connecting a nerve to a cybernetic arm to get movement than relaying an advanced image in real time into your brain. the Bionic Eye should be better then the old eyes and not some basic tech device you have to hit to get color like an old TV. I just want to use realistic surgery for my book and I’m far from a medical student, so any info would help a lot. **So my question is this: What would be the Procedure for Bionic Eye Surgery?** My idea (once the problem is solved) would be installing a holding socket inside the eye where it was connected to the brain so they could just screw in any Bionic Eye they wanted like a light bulb (but I’m very open to different ideas). Joel's new Bionic Eyes (and soon to be body) are not for free, he will be used as a military asset (he will be classified as a weapon of the state). so the Bionic Eyes should be combat capable (not a blind mans helper) hence the screw in eyes for different uses in the field. cybernetics is out on the open market but military powers are working on new and improved way to use them in warfare (some are not so legal) And just for the people that haven't figured this out yet: **This is a hundred years in the future with an advanced tech level** [Answer] You need to remove the original, damaged eyes and let the sockets heal. If the facial bones have been damaged, you need to fix those too. Then you need to measure the socket interior and 3D-print an eyeball to match. The exact internals of the artificial eye are up to you. The most complicated detaild are, in order of complexity: * Connecting the bionic eye interface to the optic nerve. You will have to connect electronic bits to tips of neurons individually if you wish to get eyesight at least as good as the original capacity the cyborg had. * Training. The cyborg's brain will not understand the signals coming in as soon as the eyes are activated. Neural networks, even natural ones, need training. This may take anywhere from days to months. The eyes may stream 4K video to a computer but the cyborg will only see static, then blotches, then blurry images until his brain gets used to the eye's signals. * Focusing and adjusting for darkness. Our eyes are not just passive cameras on a single configuration. We can move small parts to adjust focus and to allow more or less light to come in. This is done by muscles. The artificial eye will need servomotors for that, or in the very least solid state electronics that will take input from cyborg's nerves and do the equivalent of what a pupil and the lens would do. The cyborg will need neural network training for those too. * Self cleaning. Eyes are cleansed by the immunological system and the flow of acquous humor on the inside, and tears on the outside. Maybe you can reuse the tear ducts for the outside, but inside maintainance is on the bionic eye engineer. * And finally, make the eye out of a material that does not cause rejection. But it's the future, so maybe that is already solved. [Answer] > > What would be the Procedure for Bionic Eye Surgery? > > > I assume you don't want to publish the detailed surgical protocol on some high impact score journal, but rather give some plausible explanation on how the thing might work. Thus: * CCD like device to translate a light signal into an electric signal (roughly what the retina does) * suitable interface between the CCD and the optical nerve, so that the electric signal are transmitted to the brain * suitable training for the brain to learn to process the received signals. [Answer] The cyber socket indeed needs to be connected to the optical nerve, and possibly to the nerves that go / went to the muscles controlling the eyeball (this could be monitored through myoelectricity sensors or active electrodes). As its the advanced future, you can either have: * the cyber-socket talking the same protocol as the biological eye and muscle * another implant directly in the vision center of the brain receiving data from the socket. Avoiding the eye connecting directly to the optical nerve sounds like a good idea. If your eye-bulbs are mobile, they could be actuated through mems / ultrasonic transducers like the focus motors in camera objectives, or be fixed like insects and having the software part of the eyesocket change the focus zone that is fed to the optical nerve. Or just feed all the field of view data to the brain through the nerve and have your cyborg learn to deal with it. You eyesocket can be a passive component like an eye socket providing just plug and control functionality, or an active component that transform all the eye-bulbs in the same vision protocol. Or have the assist mode be the socket doing some simplification of the data and have an advanced mode where the eyebulb feed the data directly to the optical nerve with only protocol translation and no filtering or dumbing down. [Answer] Another possibility to consider is that only the anterior segment of the eye is damaged: no lens, no iris, no cornea, no vitreous. No worries! Here's the procedure as I see it. We have the funds. . . We have the technology. . . We can rebuild! Since we're 200 years in the future, I'll posit some things a little in advance of what we can do now. **Introduction** Due to advances in bio-mechanical material & artificial tissue science, we're able to coat a technological device with a kind of immune-transparent tissue, composed of lab-grown and host-derived components. Rejection is impossible. The implant is secured within a bony~cartilagenous~connective tissue matrix that effectively seals and secures it within the host's body. The implant itself is based on centuries old technologies, applied in a new way: lasers, the IMT & the IOL, the latter two of which serve to replace the biological lens as a light focusing device. Our device, the **INTROCULUS** *ITVS* (the Intraocular Total Vision System) comprises three essential functions and several variable ancillary functions. Of course, central vision & peripheral vision are keys. Much like the IOLs of old, the ITVS focuses incoming light onto the biological retina, allowing the Cyborg to "see normally". In addition to normal colour vision, the ordinary lens system allows for "normal" low light vision. What distinguished the ITVS from the competition is the rest of the story: we've known for centuries that, apart from standard colour vision, humans are able to see and process UV and IR light as well. ITVS takes advantage of this ability: when the Cyborg engages IR-Vision, incoming IR radiation is translated into ultra rapid IR laser bursts that the retina can see; when the Cyborg engages UV-Vision, the nano-computer shunts the UV light signals to predetermined parts of the retina in succession, allowing the Cyborg full UV vision without the side effects encountered by unaltered humans. **Procedure** *Preparation, Phase I:* Neuro-Ophthalmology team will address the remaining portions of the globe and prepare them for implantation. Remaining vitreous & any foreign bodies are removed; ocular muscles are disinserted; edge of the globe is prepared by excising non-viable tissue and repairing tears with standard adhesive techniques; the retina and inner surfaces of the globe are scanned and measured in the minutest detail, down to the atomic level in the case of the nerve receptors within the retina; finally a *biopatch device*, which is basically a biological bandaid, is trimmed and secured to the globe-stump. *Preparation, Phase II:* Cranio-Maxillo-Facial team will address all aspects of repairing facial fractures, in consultation with Plastic-Reconstructive team. Particular attention will be paid to the preparation of the orbital bone structures. CMF team will take 3D measurements of the bony orbit and surrounding bony tissues. Plastics will secure tissue samples for Rapid Growth Autoreimplantation. (Basically, they'll take some skin and connective tissue & fat cells for directed cloning & tissue development: the Cyborg will end up with a natural appearing face, eye lid, etc. *Preparation, Phase III*: Neuro-Ophtho team in conjunction with CMF will review the gathered measurements and begin the process of 3D tissue extrusion of the ITVS skeleton. The ITVS skeleton is the latticework into which the non-biological device will be housed. Precise measurement are required in order to calibrate & aim the data stream from the device to the retina. Measurements will be sent to the Introculus.co labs where bespoke devices will be built to the CyberForce general command's specifications for this unit. Each device is tailor made for an individual cyborg, with tolerances of less than .001mm (physical dimensions) and 1:1 concatenation between device signal output device and its designated array of biological optic nerves. *Implantation:* Once all the devices, Introculus Bio-Skeletons and tissue packs are ready, all teams will converge for implantation. Plastics will open the face and remove the external tissue bandages. CMF will prepare the orbital bone for the skeleton implant while N-O connects the device to its biological housing. Preparation of the orbit involves precise alignment of the Introculus Drill Gantry, a device that bores all fastener holes and reams out all areas of native bone where the implanted Skeleton will reside. They will also reserve the removed bone dust & blood for use later. N-O will now remove the *biopatch device* from the prepared edge of the globe and secure the exterior of the globe to the first part of the Skeleton. This is a simple 3D extruded bio-lattice that, with "bioglue technology" supports & holds the soft globe in a predetermined attitude and position, based on measurements taken earlier. The posterior portions of this bio-lattice will be filled by Plastics with lab generated orbital fat tissues which will, as with the original human tissue, serve to protect the remaining globe of the eye and the optic nerve. It also serves to "fill up the space" in the orbit. N-O will come in again to prepare the power filaments: fine bio-neutral wires that will convert physical movement (whether from facial muscle movement to the rhythmic motion of the tiniest of arterioles) into electrical energy and thence convey that energy to the ITVS device, which will then be fully powered. Once the bio-lattice Skeleton is in place, N-O will simply slide into place the ITVS device within its housing. Again, bioglue technology will be used to seal the two halves of the Bio-Skeleton together: the engineered tissue surrounding the housing & device will bond seamlessly with the tissue of the retina. The seal will allow *NuVit*, an optically enhanced clear fluid vitreous humour replacement system, to fill the space that was once the man's posterior chamber. Once the device is placed, Plastics will once again take over. The once barbaric procedure known to history as the "microsurgical free flap" is now perfected in the form of a nano-surgical autologous facial flap. Essentially, the man's own tissues have been rapidly engineered to replace the temporary "bandaid" tissues. Nano-lasers and microscopically controlled instrumentation assures that an adequate blood supply is routed to the new tissue. Bioglues and tissue regeneration techniques allow for the flap to be perfectly trimmed & inset within two hours and initial tissue fusion to occur within the first post-operative day. **Conclusion** *Post-Operative Healing:* Various modern techniques are used to ensure rapid and biologically integral healing of tissues & bonding with bio-engineered components. Continuous monitoring of blood levels of oxygenation & tissue regeneration factors (both systemically & locally at the flap locations) alert Nursing & Medical well in advance of a crisis. Flap death is now a very rare artifact, with incidence less than 0.5% Of more concern is the mental state of the host as his levels of consciousness waxes and wanes after surgery. *Post-Operative Therapy:* As with any bio-technological implant, a Cyborg must undergo a rigorous programme of post-operative training and therapy. In many cases, such as with the implantation of so-called "bionic arms" and "legs", where neuro-pathways have been utterly destroyed, this regimen may last many weeks or months as the brain, which already "knows" where it wants the hand or foot to go must relearn how to get that message across to the hand or foot. With Introculus's hemi-ocular salvage technique, much of the retraining regimen required by the older "whole eye" bionic replacement process, is made moot. Because the retina and optic nerve remain intact and active, the training regimen immediately proceeds on to the final stages: device calibration, facial muscle to device movement exercise and most importantly, device-retina training. This concludes our presentation on the implantation procedure for the Introculus ITVS Device. Thank you for considering Introculus for all your CyberForce's vision needs! [Answer] One of the things that none of the answers preceding this one has addressed is the issue that this is post-trauma replacement, not simply a matter of replacing existing good eyes with better ones, or even replacing blind but intact eyes with functional ones. You have major trauma here, and nerves tend not to react too well to trauma at the best of times. A nerve bundle is not a bunch of short cells connected in series and multiplexed in parallel, they are typically bundles of single very long cells. A neuron has a cell body, a number of shortish "receiver" branches called dendrites, and a single long axon that goes to wherever the output signal is required. This means that the neuron's body is typically quite close to the source of its signal(s). In the case of trauma as severe as this, it is quite likely that optic neurons' dendrites and bodies would be damaged or destroyed. Should that be the case, while the neurons' severed axons would still be present, they would be like a stick cut from a tree - not capable of surviving in isolation, let alone functioning. This is a roundabout way of saying that you are highly likely to have nerve mortality all the way from the eye to the sub-cerebral optical ganglion. In order to be profitable - and prostheses like these *would* be made to be a source of profit for their manufacturer - a therapy must be as broadly applicable as possible, not limited to a narrow range of edge cases like damage to only the front of the eye, that leaves the retina (a very fragile structure) completely intact. This leaves us with three possible ways of integrating the inorganic hardware with the biological wetware. In all 3 cases, the facial trauma must be repaired and sockets for the inorganic optics implanted, but the process of making the data connection differs: 1. The lowest-tech option is to run electrical cables from the eyes to the optical cortex at yhe back of the brain, where the cables would terminate at the neural bodies of each of the optical cortex's neurons. There is a reasonably simple physical mapping between the visual field and the arrangement of the optival cortex's neurons, so once the connections had been made, it would be a one-off process to fine-tune the mapping so that no relearning would have to take place. 2. The intermediate tech option would be to use nanotech assemblers to assemble new cable to replace the optic nerve bundle all the way to the sub-cerebral ganglion, and then as in 1, map cerebral cortical neurons to hardware pixels. This would be a little more difficult, as deriving an approximate preliminary mapping would be more difficult, but not impossible. 3. The highest tech option would be to not to map the optical image received by the hardware to the optical cortex at all, but to process the incoming data in the hardware and pass the output deeper into the brain, bypassing the optical cortex almost entirely, so, instead of showing the brain an image, the hardware would be telling the brain what it sees more directly. Of the three approaches, #1 is the most invasive, requiring opening the cranium and running cabling through the skull, and #2 is the least invasive, with nanoassemblers removing only dying severed axons and replacing them with microscopic wires. So, why would we even consider option #3, considering that it would involve making connections to many, if not the majority of the neurons in the brain? Consider this: with a mapping made between the pixels of the prosthetic eye and the optical cortical neurons, we can duplicate the pre-existing visual capabilities - and no more. Sure, the manufactured prostheses could have perfect vision, but the system is limited by the number of neurons in the optical cortex. You simply cannot increase the resolving power of the eye without having to downsample the input in order to send it to the brain. Only RGB output from the eye would be 'native', and any other output would have to be substituted or overlaid onto the optical field. While the initial training is *not* training the human to accept incorrect signals, but rather training the *hardware* to produce an output acceptable to the patient, the human brain did not evolve to process all the extra layers of data that the manufactured optics can generate, so learning to interpret the different modes of operation would still be time consuming. With the third option, the optical hardware does the image processing and interpretation, and passes the interpretation to the patient's brain. With the correct connections, the eyes would not need any artificial separation of display modes,the interpretation of all available modes would be passed simultaneously, and they would seem completly normal to the user - the optical processing system in the eyes would present the data in such a way that its output would not be so much seen as experienced, and its higher resolution, broader spectrum and other capabilities would be presented in such a way that it would seem as natural as the user's former wetware human Mk1 eyeballs' output. Once the patient's brain had been mapped and the neural lace grown inside the brain, the eyes would be pretty much plug and play. The neural lace would also have the side advantage of reinforcing the whole brain against impact damage. So, what would we be able to achieve in 100 years? Option #1, almost certainly, Option #2 is a strong possibility, and Option #3 would be dependent upon AI-led and conducted research over this timeframe, as it would most likely take an intelligence without human limitations to understand the inner workings of the human brain to the degree required. ]
[Question] [ If a subspecies of human had bones that were made of an almost unbreakable material (let's just ignore any adverse effects this might have) how much would these bones help them to survive falls? Would the bones prevent the shattering of the legs, or would the increased durability of the skeleton cause even more damage to the internal organs? For the purpose of this question, consider the bones similar to Wolverine's adamantium-coated bones: inflexible and uncompressible. [Answer] This is worse than normal bones. There is a reason why cars bend and twist so much on a collision. That absorbs energy from the collision and keeps you alive. Used to be that a car could hit a post at 60mph and not bend much, or at all depending on its make. People inside would be turned into a pulp. Same goes with unbreakable bones. The less damage your bones take from a high fall, the more of that damage goes pretty much everywhere else. You should consider shock absorbing soft parts instead. [Answer] not much. damage to internal organs will still be there, along with torn muscles and dislocated joints. [Answer] Somewhat flexible, but nonbreakable bones would be of a big health benefit - medium falls usually result in fractures, and healing takes days and weeks, greatly affecting survival of species in the wild. But big falls would be fatal all the same, because it's damage to internal organs, not bones, that makes a fall fatal. [Answer] It depends on how far the fall is, and what angle you hit the ground. The [highest recorded G's](https://en.wikipedia.org/wiki/G-force) that a person has experienced and survived was when Kenny Brack crashed into Tomas Scheckter. It was 214G, which is about 2097 m/s^2. According to [this calculator](https://vaultcanada.org/FallCalc#Calculator) that's equivalent to something like a fall from 80 meters with 4cm stopping distance. Kenny Brack suffered multiple broken bones, but the wikipedia article doesn't list any internal injuries, so I'm going to assume that his only internal injuries were related to the fractures. I assume his flesh experienced almost the same G force that his bones experienced, so I would take this to mean that a person could remain relatively uninjured up to that point. So, yeah, if I'm not terribly mistaken, then a person with unbreakable bones could stand up to about an 80 meter fall with minimal damage, if they landed the right way. Depending again on how they land, a fall from as low as 10 meters could give enough G's to knock them unconscious. I want to note, against some anticipated objections, that unbreakable bones does not mean that the person will be perfectly rigid on impact. The person's joints will still bend in the normal way, cushioning the impact only a little less than what you'd get with bones. Eventually, though, if the fall is from high enough, that small amount of cushion you get from your bones breaking will make a difference and save your internal organs. I don't see any good sources online about where that cutoff is, but I wouldn't want to test it any higher than 80 meters. [Answer] While I agree with the majority of answers that unbreakable bones will not do a significant amount of help preventing other internal injuries from occurring. The problem lies in the amount of negative acceleration the occurs when landing from a fall, unbreakable bones means that there is just a little less distance for the force to be dissipated than in the case a bone breaks. Something that is not mentioned in other answers however that does give an advantage to unbreakable bones is that you will not have to worry about bone splinters adding further complications to the internal injuries you would receive. ]
[Question] [ In a Galaxy where there are numerous Earth Like worlds, and FTL Travel is possible but only by a small number of species, possibly only by Humans, perhaps they just happened to get there first. In a similar way to Star Trek, where large FTL ships go forth and look for habitable worlds, they regularly come across intelligent life, in various stages of technological evolution For argument, lets say the ships have whatever Stealth is required that they can observe these planets and not be noticed. I need a way to classify these species (not in a racist way) based on their technology. I feel I need more fine tuning then the Kardashev Scale Offers. I can name the scale and have it be 1-100 or however many levels I choose, with level x being the level at which my ship would make contact with the species below, and anything before that being worthwhile research on early development of an intelligent species. my Humans are at Level 10. 1. Pre-Primitive (not able to use tools of any type) 2. Primitive stone tools, basically Stone Age) 3. Able to use surface metal deposits to make tools 4. Regular use of Metal Tools including mining, however not an industrial Society 5. Industrial Society, basically after the Industrial Revolution 6. Internal combustion Engine 7. Nuclear Capable 8. Capable of Limited Interplanetary travel and Satellite positioning (Current Modern Day Level) 9. Capable of transit between planets within own Star System, but not inter system 10. Capable of interstellar Travel 11. Capable of Inter Galactic Travel The Question: **I need to know what technological breakthroughs can mark the transition from one stage to another that i'm currently missing** in the way that Pre-nuclear and post nuclear does. I know that several other scales exist similar to the Kardeshev Scale like Information mastery by Carl Sagan, which deals with how much, but all of them are based around the way a civilisation uses power or information, Carl Sagan's comes close to what I want but doesn't quite fit the bill. also a lot of these don't incorporate the more primitive species that my Humans might want to research. I'm also considering a Morality Level (from a human perspective obviously), along with another for how widespread they are so the scientists would visit a planet because they want to study the Bob species which is rated as something like B-5-T, First being how widespread/numerous the species is, second being Tech Level and third being Morality (or something better as the name) Some levels such as abolishing Slavery would come under the Morality Scale as they aren't based on Tech/tools. [Answer] I see a pattern in your list that we can take advantage of. Let's start by building a list of relevant technology groups. This list could be detailed and miles long, but we're interested in those groups that allow us to easily catagorize the process of development. (If this list reminds you of Sid Meier's *Civilization* games I wouldn't be surprised. I played them a lot as a kid...) There are a large number of basic tech groups we could use, but let's use three to demonstrate. (Energy production would be another good one, btw, starting with the discovery of fire and ending, perhaps, with antimater or harvesting solar winds or actually discovering zero-point energy...) * Tool building * Information processing * Transportation OK, now let's list at least five major breakthroughs in each of those categories up to the present day. *(This list is very subjective, people will certainly point out where one tech was more indicative than another. That's cool, leave your comments for the OP's benefit. In the end, the list must be his, not mine.)* There's a lot of web-based info you can draw from to do this. I used [this site](http://www.notevault.com/blog/3-millon-years-of-construction-technology) to put the tool list together quickly. I'm not sure I'd trust the date ranges they're suggesting, but the list is pretty good, and focusing on just one item, the hammer, is reasonably indicative of the supporting tech needed for the advancement. Not surprisingly, you'll find that the basic technologies (e.g., tools) are replaced by more advanced technologies (e.g., information processing) as critical indicators of advancement as time goes on. In other words, "tools" only defines advancement to a point becuse the technology gets to the point where no matter what was done to advance the development of a tool, it's really just "more of the same," the application of new manufacturing tech to the same old tool. Case in point: **Tools** * The hammerstone(stone age) * Handles & Leverage * Metal hammer heads * Water-powered hammering (fixed in one place) * Pneumatic hammering (mobile but tethered) * Electric hammering (fully mobile, but still using a hammer head) * Magnetic hammering (think "rail gun," literally, no physical hammer head) *Why not "metallurgy?" Because while fundamental to many technologies, the advancements in metallurgy are more difficult to discern than the results in advancements in metallurgy — like a better hammer. It is, in my mind, too imprecise to be useful as an indicator of technological advancement.* **Information Processing** * Vocalization (using voice to express ideas) * Cave drawings (using our eyes and fingers to express ideas) * Music (using something other than voice to experess ideas) * Letters * Paper * Radio * Computers (fixed application) * Software (flexible application) * Modems (Using sound-not-voice to express ideas more complex than emotion) * Networking (leveraged application) * Cybernetics (using something other than our eyes and fingers to express ideas) * Artificial Intelligence (something not human is finally expressing ideas) **Transportation** * Domestication of Animals * Shoes * The wheel * Springs * Cams & Gears * Steam * Combustion * Flight * Rocketry * Magnetic propulsion * Gravitic propulsion * Sublight propulsion * FTL propulsion * Artificial wormholes It's obvious that some of these technologies merge in the timeline with others. We want to select the most indicative (call it "obvious") advancements for ease of catagorization. Thus, merging the lists gives us (remember, this is just one perspective, please don't argue about whether or not I picked "the right indicators."): * Vocalization * The hammerstone * Handles & Leverage * The wheel * Letters * Music * Water-powered hammering * Steam powered tools * Flight * Radio * Computers * Rocketry * Networking * Cybernetics * Magnetic propulsion * Artificial Intelligence * Gravitic propulsion * Sublight propulsion * FTL propulsion * Artificial wormholes **Some observations** 1. You'll notice that the time between steps gets closer as time moves forward. That's because knowledge advances on an exponential scale. Expressing the difference between you, the advanced observer, and them, someone almost as advanced and almost ready to be observers themselves, should be difficult. This means your scale must either become infinitely fine into the future or you give up precision for convenience. 2. The future is remarkably difficult to predict. I'm fond of the game (I'm about to reveal my age) "Masters of Orion II." In that game, when you've discovered all the known tech there is, you continue by discovering "future tech 1," "future tech 2," etc. You, the author, are in the enviable position of needing to creatively predict the future. That's wonderful! The very best science fiction creates plausible future details. The British TV show "Doctor Who" is credited for (or at least they lay claim to) predicting remote garage door openers. Do this well, and you'll have readers eating out of your hand. [Answer] Plenty of science fiction games have similar concepts. To pick just a few examples, from ancient to new. * Traveller was one of the early ones. It went through several editions, with slightly modified TL systems. * GURPS is another detailed system. * The tech trees in the Civilization computer game series. * The Twilight Imperium board game. When you are picking break points for futuristic tech levels, consider what makes a big difference -- often being shot at, or dodging a missile. * More compact or more efficient sublight maneuver engines. An increase in I*sp* or thrust to mass ratios would make a big difference for space combat. * More efficient weapon systems. Say beam weapons go from "good for point defense" to "good against starships" at some point. * Artificial gravity and/or acceleration compensation. * FTL sensors and communications. The Morality Levels you mention are iffy because they **don't** have immediate game effects. Both the United States and the Soviets had good scientists, but in the end the economic potential of the West won. But it was a close call. You took the abolition of slavery as an example. But slavery in the Hellenistic city-states, the American South, and medieval serfdom were completely different things. Each could be abolished at different points of your fictional species, or even reintroduced. [Answer] In human history, you've got about 2,000 years between your level 4 and level 5. which covers massive leaps forward in technoliogy from ancient Greece to the Renaissance. You'd need to insert at least one classification there somewhere. And yes, we did evolve socially as well. There were all kinds of slavery throughout history, and don't forget to include the fact that slavery itself was a step forward from the times when you just ran in and murdered everybody. But don't forget, social advances aren't independent from technology. The industrial revolution made slavery obsolete, as it was very dangerous. You could replace a free man at no cost, but you had to buy a new slave. In The USA, slavery died off in the north because they became industrialized and you needed educated or at least skilled workers, you also had a level of fatalities that would make owning slaves prohibitive. [Answer] Since we are talking about aliens we can't expect the same history's "linearity" that's written on our books, therefore i wouldn't go with a one-dimension scale because it can't label a civ as a whole. Multi-dimensional scale, with at least two dimension (morality and energy control). I'm thinking about something similar to the [Internal Protection Code](https://en.wikipedia.org/wiki/IP_Code), which indicate the device protection level respect to water and dust, wich are indipendent agents. I'd write down less than ten level for both moral/civil and energy/science milestone, and then create a codex where "zero" is amoral and pre-tool level and "ten" is galactic peace and interstellar teleport. Therefore you can use description like: * "Civ23": slightly better than "animals", but with iron age tools (don't ask me how is it possible, they are alien for some reason!) * "Civ47": they cooperate obeying a strong leader/dictator, they can travel to other planet in their own system. (Like Starcraft's Zerg but with less technology) * "Civ08": amoral civ made by ipertechnological A.I. with the only purpose to harvest as many energy as they can. (Like WH 40K Necrons, then without Space Marines we are fuck3d...) * "Civ99": civ made by interstellar teleporting, illuminated, peaceful tibetan cyber monks (i'd really like to meet one of this guy :) ) I think that these examples are enough to clarify the concept of multi dimensional scale, you could also add another dimension like "probable impact on other civ" or whatever. You can also get ideas from the [RAL scale](https://en.wikipedia.org/wiki/RAL_colour_standard), it's one of the easiest yet effective way we found to comunicate something as subjective as a color, then a similar concept could be used to indicate a civilization type. --- Edit, @Blade Wraith: Other answers offer some examples of "tech trees" but i wouldn't use our tech milestones to define other races' milestones. I doubt that an alien queen would ever try to develop tools, from the basic hammer to the a nuclear device, then "Alien" civ should be a near zero civ on the tech scale. But this doesn't mean that she can't conquer the home planet of a lvl 8 civ (current humans on your list), and how is it possible that a near to zero civ could outperform a 8+ civ, moreover starting the "planet assault" really outnumbered (1 or few VS 7 billions)??? This example shows how **this kind of scale can't really define a civ's tech power**, it could be used only to compare civs that look almost like us. The Kardashev scale is based on the energy level rather than the tech level because different civs could use different techs for the same goal, and the really difference is how many energy they can invest to reach the goal. If the Kardashev scale isn't detailed enough it could be improved, but i'd stick with energy levels. Since you are also using a Numerousness indication, i'd go with **watt availability of the civ's most powerful entity**. You can range from fractions of watt of the unicellular organism to the 10^25W "star eater" level (from [here](https://en.wikipedia.org/wiki/Solar_constant) i've estimated the total watts theoretically available to something that can assimilate our sun as 3,6x10^26 W. After that i've realized how dumb i've been because this calculation is the theoretical equivalent of the Dyson sphere, which is quite famous and already calculated). On a second tought the scale could begin at 100W or 1KW, since anything below isn't that interesting, it's good to know that the "civ" exists but nothing more. You can divide the whole range of interest (10^3 - 10^30 W) in steps and, for instance, have this kind of scale: * 1: from 10^3 to 10^5 W * 2: from 10^5 to 10^7 W * 3: from 10^7 to 10^9 W * etc... To give some hint about the different power level you can add examples of some know entities that fit in the different level, but **these entities should be introduced as examples and not as milestones**. For instance you can put these examples: * 1: from 10^3 to 10^5 W - Roman war chariot * 2: from 10^5 to 10^7 W - Supermarine Spitfire * 3: from 10^7 to 10^9 W - Nimiz class aircarrier * 4: from 10^9 to 10^11 W - fiction... * ... * 12: from 10^25 to 10^27 W - Death star Unfortunately this scale (imho) works better but i have to admit that's not really funny to use... [Answer] Kardashev (<- Spellcheck suggests "correction" to "Kardashian", civilization is doomed.) or Sagan scales are based on laws of thermodynamics and basic properties of life. As such they can be safely assumed to be directly applicable to all civilizations and forms of life, organic or inorganic, sentient or not. They also give a single number that is directly, meaningfully, and accurately comparable between civilizations and forms of life. Additionally these scales give a real number. There are no jumps or discontinuities. The value is 4.25 ± 0.01, not "maybe 4 or 5, depending on how you regard the copper mining technology in Kingdom of Chalice". So a civilization looking for a universal scale would still use the Kardashev (easier to do from orbit than Sagan) scale and just expand it to handle the specific needs they have. An obvious expansion is to also measure the density distribution of energy. Wonders of statistics would give all kinds of fun stuff from this and the peak values, sustained and transient, civilization achieves would give a valuable and universally comparable "just a number". An example: If a civilization achieves a peak transient energy density comparable to a nuclear weapon, whether it was produced by an actual nuke and whether the locals ever considered weaponizing it, they have the potential to attack anything vulnerable to nuclear weapons. But more importantly, if your civilization needs more accuracy (as they would) they would use separate data specifically targeted for special needs. No single datum can serve all such needs and trying would only lead to disastrous and preventable errors. The likely solution would be simply to define a large number of generic protocols for tasks you do in contact with the aliens and then use those as classifications instead of trying to classify the actual aliens. The aliens are under no obligation to fit your neat categories or levels, survey service personnel is. This also gives all the data people actually need (if the protocols are correctly designed and selected) without incomplete, misleading or useless noise. So instead of telling the expedition the aliens have space ships of level 12 (except see link for the details of propulsion and this link for details on weapons), they would be told that survey fleet protocol Charlie Able with options Gamma and X-ray is active, please read the detailed analysis if you have time, summary even if you do not. Same with social protocols and such. You could still categorize the aliens based on which protocols are active for them, but it would be based on actual categories with concrete meanings and exact definitions, not on trying to categorize things that never actually exactly match your neat abstract definitions. You'd want to give them personal digital assistants to remember which protocols are active and what they mean probably integrated into a personal communicator so protocols can be changed on the fly. Additionally the bureaucracy involved in developing and assigning these protocols has good comedy or parody potential... Imagine being on an alien planet when your PDA tells that first contact protocol X-ray X-ray is now in effect and finding the protocol has two items: "Send your final messages and update your last will" and "Activate the self-destruct on your suit on full sterilize setting and remote trigger. REMAIN SUITED AT ALL TIMES.". ]
[Question] [ Many games have various side bonuses on their armors other than just defense. These bonuses can often be active things like having a ghost thrall to protect you when wearing a special armor or more passive bonuses like ''+15% strength''. Leaving aside the active bonuses, how can an ancient armor directly increase ones strength when wearing it? Is it actually possible without ''magic'' or high futuristic technology ? [Answer] **Less strength penalty = strength bonus?** Here is a way super armor could improve strength without invoking magic. It improves strength in comparison to other armored situations. Suppose you have 16th century plate armor. It will protect you. It will also slow you down and limit what else you can carry, because it is heavy. Your primitive plate armor comes with a strength penalty. Now you have 22cond century nanofiber / polymer armor. It protects you as well as the plate armor did, but you have a minimal strength penalty or none at all. Compared to your situation wearing the plate armor, the high tech armor has increased your strength. Neither of these armor situations increases your strength as compared to you wearing only your gold lamé shorts, nor do these armored situations get you looking any better than you do in those shorts. [Answer] Aside from @Willk 's great answer, if the armor is actuated somehow. Steampower, Electric cirquits or just plain magic to help move the joints and make your movements harder to stop with outside forces would fulfill the requirements. Regardless of what you pick, magic is going to be involved somehow to shortcut some requirement. Steampower for example would need too much water and fuel to work comfortably unless you have guys running after you carrying water and fuel or magic it somehow, and any actuator would need computing power to keep the movements in line with yours and smooth. [Answer] **Biotech.** The only real technology needed here is a basic knowledge of Electricity and Muscle Anatomy (of course much more than a basic understanding is needed if you want to make this more realistic). Think the "Pickle-Rick Fights Rats" sequence from Rick and Morty, where he makes himself a suit of armor that enhances his strength without any advanced technology, only the advanced knowledge to construct it. But that's the big problem with the idea. It really depends on what type of Ancient Empire made the armor. An Atlantis-type society of science well ahead of their time would really be the only type to come up with something like this, anything else would just be unrealistic (unless a single brilliant ancient scientist had a remarkable amount of free time). Even if it's not the most realistic, it's the only somewhat-plausible solution without incorporating Magic or Technology I can think of. [Answer] > > Many **games** have various side bonuses on their armors other than just defense. > > > Right: # Games Where breaking the laws of physics in the name of fun is perfectly doable. > > how can an ancient armor directly increase ones strength when wearing it? Is it actually possible without ''magic'' or high futuristic technology ? > > > Make no mistake: **It can't.** There's no way that loading on lots of **dead weight** (whether as plate mail -- weight: 27kg -- or a leather or iron curiass -- only 3 kg) will make you stronger while wearing it. [![enter image description here](https://i.stack.imgur.com/kYzGF.jpg)](https://i.stack.imgur.com/kYzGF.jpg) <https://c1.staticflickr.com/4/3408/3327580382_5d898f4104_b.jpg> [![enter image description here](https://i.stack.imgur.com/8AQDm.jpg)](https://i.stack.imgur.com/8AQDm.jpg) <https://www.outfit4events.com/runtime/cache/images/redesignProductFull/pef-6003b.JPG> [Answer] It's all a matter of chemistry and biology. Starting in the 19th century people began isolating and identifying [Anabolic Steroids](https://en.wikipedia.org/wiki/Anabolic_steroid#History), but they had been in use (from animal gonad sources) long before they were chemically identified. Your "magic" armor is either biological (shells/leather/other tissues) or is otherwise treated with biological material. It naturally secretes the hormones stored while the animal was alive, imbuing those who wear it for any length of time with increased strength. [Answer] Maybe not in the very truest and most technical sense, but consider the case of compression clothing. Compression clothing is believed to improve performance and recovery times when exercising and many people swear by it. However according to this [article](https://well.blogs.nytimes.com/2015/01/14/can-compression-clothing-enhance-your-workout/), there is little to no evidence to suggest this is the case, or why it would be the case. And here's the important bit; despite there being no evidence and no reason why it would improve your performance, those people who believe in it feel they perform better. In other words it's a placebo effect. Now I doubt modern compression clothing is possible in an historic setting and I'm not sure old fashioned corsetry could do the job, but really it doesn't need to. You don't need your armour to actually do anything (though something noticeably different about it would probably help) all you need to do is tell your warriors their armour has been enchanted by the most powerful mages in the land, or blessed by their gods, and they will *feel* stronger. It may not be the kind of effects games prescribe to magic items, but it could still give that performance boost. ]
[Question] [ I am working on a story and came up with a doubt regarding an explanation given for time travel using wormholes as portals. The below given is taken from Wikipedia link: <https://en.m.wikipedia.org/wiki/Wormhole> > > "For example, consider two clocks at both mouths both showing the date > as 2000. After being taken on a trip at relativistic velocities, the > accelerated mouth is brought back to the same region as the stationary > mouth with the accelerated mouth's clock reading 2004 while the > stationary mouth's clock read 2012. A traveler who entered the > accelerated mouth at this moment would exit the stationary mouth when > its clock also read 2004, in the same region but now eight years in > the past. Such a configuration of wormholes would allow for a > particle's world line to form a closed loop in spacetime, known as a > closed timelike curve. An object traveling through a wormhole could > carry energy or charge from one time to another, but this would not > violate conservation of energy or charge in each time, because the > energy/charge of the wormhole mouth itself would change to compensate > for the object that fell into it or emerged from it." > > > Well let's consider A and B be two portals kept next to each other and let there be two clocks with those portals A and B respectively and those clock shows the synchronized year 2000. Let A be on earth and portal B taken along with the clock is taken on a journey somewhere in high velocity or speed. After journey let these two portals be kept next to each other as before. For an observer it could be seen that the clock kept with portal A which remained on earth shows year 2012. And the clock kept near portal B shows 2004 (due to time dilation). Like the time dilation happened to Copper in movie Interstellar. Both the portals are brought back and kept side by side. Well, when comparing their ages we could understand that only their ages differs. I mean portal A is 8 years older than portal B. But if I were to go through portal B I will be exiting portal A the year I entered and not in the past or future. Then how could we use it as a time travel machine or how time travel works with wormholes? a similar thought experiment is quoted below, > > Kip Thorne who is the Feynman Professor of Theoretical Physics, Emeritus, > at the California institute of Technology proposes a thought experiment > in his 1994 book "Black Holes and Time Warps" (W.W. Norton & > Co. 1994) > > > Say he obtains a small wormhole, which connects two points in space as if they were not > separated by any distance at all. [What's New in Black Holes? A > conversation with Kip Thorne] > > > Thorne takes his wormhole and puts one end in his living room, and the > other aboard a spaceship parked in his front yard. Thorne's wife, > Carolee, hops aboard the spaceship to prepare for a trip. The two > don't have to say goodbye, though, because no matter how far away > Coralee travels, they can see each other through the wormhole. They > can even hold hands, as if through an open doorway. > > > Carolee starts up the spaceship, heads into space and travels for six > hours at the speed of light. She then turns around and comes back home > traveling at the same speed — a round trip of 12 hours. Thorne watches > through the wormhole and sees this trip occur. He sees Coralee return > from her trip, land on the front lawn, get out of the spaceship and > head into the house. > > > But when Thorne looks out the window in his own world, his front lawn > is empty. Coralee has not returned. Because she traveled at the speed > of light, time slowed down for her: What was 12 hours for her was 10 > years for Thorne back on Earth. > > > Now, as Thorne and Coralee hold hands through the wormhole, they are > each traveling in time. Coralee has landed on Earth 10 years after she > left, and there she will meet Thorne, 10 years older. But she can > still reach through the wormhole and find Thorne, who is only 12 hours > older. Thorne can step through the wormhole and find himself 10 years > in the future, or his future self can step back 10 years into the > past. > > > If I am wrong on my explanation please explain it in detail. THANKS FOR YOUR VALUABLE ANSWERS. [Answer] **You're asking us to explain whether or not something no one has yet proven to exist can do something that only some physicists think it can do.** ***What answer are you expecting?*** Physicists can show you how the mathematics supports the possibility of time travel. However, it depends on cutting-edge concepts like the [Casimir effect](http://math.ucr.edu/home/baez/physics/Quantum/casimir.html) that we're only just beginning to understand. Just because the math supports it, doesn't make it so. Just because we've found a bit of evidence that suggests the possibility, doesn't make it so. > > As [Stephen Hawking said in a lecture](http://www.hawking.org.uk/space-and-time-warps.html), "If this were the case, it would raise a whole host of questions and problems. One of these is, if sometime in the future, we learn to travel in time, why hasn't someone come back from the future, to tell us how to do it." > > > While Professor Hawking admits to the mathematical plausibility of time travel, he suggests in that a reason we might not be overrun by tourists is that, despite early evidence such as the Casimir Effect, you can only travel into the future. From that same lecture: > > A possible way to reconcile time travel, with the fact that we don't seem to have had any visitors from the future, would be to say that it can occur only in the future. In this view, one would say space-time in our past was fixed, because we have observed it, and seen that it is not warped enough, to allow travel into the past. On the other hand, the future is open. So we might be able to warp it enough, to allow time travel. But because we can warp space-time only in the future, we wouldn't be able to travel back to the present time, or earlier. > > > But, despite these observations from a man who knows more about physics than I ever expect to know about anything and everything in my entire life, there is a question that is really important... ***Why do you want to know?*** If you're writing fiction, then allow it or not. There's enough mathematics and enough opinions in both directions that you can use the concept (as a great many already have) in any way you wish. ***The simple reality here is that nobody knows. Nobody! Wormholes, higher dimensions, time travel, are all extrapolations from theoretical physics that are described in mathematics but not actually proven to exist in any way, shape, or form. Your guess is as good as ours — there's simply no actual proof. So, tell yourself yes or tell yourself no, either is as good as the other.*** [Answer] > > Is time travel ... possible logically? > > > **TL;DR**: No. Time travel is clearly impossible, as it would cause paradoxes. Time travel is a staple of science *fiction* because of its impossibility in reality. But it is really more like magic in that it bypasses logic and requires a suspension of disbelief. So the answer to "Can we use this process to achieve time travel?" is going to be no, regardless of the process. The immediate flaw with this particular suggestion is that relativity does not work that way. There is no "clock". Two different points have no shared time. One of the major points of relativity is that there cannot be [simultaneity](https://en.wikipedia.org/wiki/Relativity_of_simultaneity) in time without simultaneity in space. Wormholes would not work that way either. A "wormhole" is two points in three dimensional space that are far away from each other in that three dimensional space. But the two points are close together in a higher dimension space. Not clear? Take a sheet of paper. Its surface defines part of a two dimensional space (which we call a plane). Pick two spots on the paper that are not close to each other (but are on the same side of the paper). Now bend the paper such that the two dots are touching. So now you have a wormhole in the two dimensional plane. This works because the two dimensional plane of the paper is in our three dimensional reality. Now try moving one of the dots without moving the other. If you do this, you break your wormhole. They are no longer adjacent in the three dimensional space. To maintain the wormhole, you have to move both at the same time. [Answer] You are building a world and in your world wormholes, as we understand them, are real. Therefore, according to your scenario portal A has remained on Earth while portal was transported at relativistic velocity and returned to Earth. A clock at the mouth of portal A would show 2004, while portal B's clock shows 2012. This means there is a time differential of eight years between the two portals. Let's move forward in time to year 2048 and Bob decides to step through portal B. When he emerges from portal A he will have arrived in 2040. This is due to the eight year time difference between to the two portals. Unfortunately, Bob doesn't have the correct visa for 2040 and is sent back through portal A. he re-emerge from portal B back in 2048. Alice, on the other hand, steps into portal A in 2048 and when she exits portal B she will find herself in the year 2056. Two portals consisting of two wormhole mouths with a time difference of eight years will enable people to travel in time back and forth between intervals of eight years. Specifically, in this instance, time travel can be only accomplished in eight years intervals. For example, if Alice having arrived in 2056 decides she wants to see more of the future steps through portal A again. She emerge from portal B in 2062. If she wanted to go further forward into future, say, the year 2848, then she have to pass through the pair of portals one hundred times to eventually get there (if starting from 2048). Naturally it will take one hundred passages through the pair of portals, in reverse order, to travel back to 2048. To be clear, Alice will have step into portal B to exit from portal A and keep doing this until she is back in 2048 again. Wormholes, based on the concepts we know and that emerge from our current understanding of science, although there are major caveats as to whether this could be a viable technology in the real world, however, in a fictional world using wormholes for time travel is scientifically plausible. This time travel will be limited to "jumps" equivalent to the time difference between portals. [Answer] The mathematics that we currently use to model wormholes permit such time travel. However, that is a far cry from declaring that they are actually possible. To this date, we have not yet observed a wormhole, much less one which connects different times, so we cannot say whether they actually exist. What we can say is simply that the math permits it. It's similar in nature to how you can have a problem which ends up having a negative answer and a positive answer, and we discard the negative one because it's "not physical." The mathematics of the model claims the second solution is there, but practically speaking, we never see it. As for your experiment involving traveling wormholes, it's worth remember that a wormhole is not actually a *thing*. It doesn't behave in any way like the matter you and I are used to. Its an aspect of the *topology* of space. Space itself gets a hole. Thus, you should expect the math for calculating time dilation to get exponentially more difficult. Wormholes make garden variety general relativity problems look like kindergarten assignments. As Charles Staats linked, I highly recommend reading the Wikipedia article on the [Novikov Self Consistency Principle](https://en.wikipedia.org/wiki/Novikov_self-consistency_principle). In particular, the [Polchinski Paradox](https://en.wikipedia.org/wiki/Joseph_Polchinski) may be of great value for your understanding. In the Polchinski Paradox, a billiard ball is sent back in time using a wormhole on a collision course with itself. If the ball collides with its past self, it knocks it off course so that it does not go through the wormhole. This particular paradox was solved in 1991, by Fernando Echeverria and Gunnar Klinkhammer: > > Upon considering the scenario, two students at Caltech (where Thorne taught), Fernando Echeverria and Gunnar Klinkhammer, arrived at a solution to the problem that managed to avoid any inconsistencies. **In the revised scenario, the ball emerges from the future at a different angle than the one that generates the paradox, and delivers its younger self a glancing blow instead of knocking it completely away from the wormhole. This blow changes its trajectory by just the right degree, meaning it will travel back in time with the angle required to deliver its younger self the necessary glancing blow.** Echeverria and Klinkhammer actually found that there was more than one self-consistent solution, with slightly different angles for the glancing blow in each situation. Later analysis by Thorne and Robert Forward illustrated that for certain initial trajectories of the billiard ball, there could actually be an infinite number of self-consistent solutions.[6]:511–513 > > > Echeverria, Klinkhammer and Thorne published a paper discussing these results in 1991;[7] in addition, **they reported that they had tried to see if they could find any initial conditions for the billiard ball for which there were no self-consistent extensions, but were unable to do so. Thus it is plausible that there exist self-consistent extensions for every possible initial trajectory, although this has not been proven.** > > > (Emphasis mine) Billiard balls are clearly far simpler than spaceships full of people, but they do form the foundation for how you tackle such a problem. [Answer] As others have said, time travel into the past is, as far as anyone knows, impossible. The only logically possible retro-time travel scenario that I've heard of involves the existence of multiple timelines/universes, in which a person travels, not to the past in this universe, but to a similar past in another universe. (See *The Fabric of Reality*, a popularized explanation of the multiple-worlds interpretation of quantum mechanics, written by physicist David Deutsch.) Not all physicists believe that there are multiple universes. But if you want to read some adroit hand-waving in a time-travel novel, check out Michael Crichton's novel, *Timeline*. [Answer] Time travel is logically consistent, in the sense that the physics of relativity can describe a universe in which time travel happens. There is no evidence that our universe is such a universe and strong reasons to suspect it is not -- or at the very least, that any time travel within our universe must be extremely limited. But I'll skip over these for now. **Manipulating wormholes** One of many kinds of theoretical universe in which time travel would be possible is a universe in which intelligent life has the ability to create and control wormholes, and in particular can move one end of a wormhole at relativistic speed as in the thought experiment quoted in the OP. Here are some consequences: * So far as I know, it's not logically possible to use this method to travel back farther in time than the creation of the wormhole. [I've been surprised before by relativistic time travel thought experiments, so you might want to confirm this on Physics.SE.] This neatly deals with the question of why we don't see any time travelers from the future -- they can never travel farther back than the invention of time travel. But it may put unacceptable constraints on your story. * If you don't want to invent random new laws of physics (like someone vanishing into thin air when their intervention prevents their parents from meeting), you need to obey the [Novikov self-consistency principle](https://en.m.wikipedia.org/wiki/Novikov_self-consistency_principle). In short, this means that time cannot be rewritten; when you go back in time you can't change anything. (You can try, but somehow it will turn out that your efforts were already part of the timeline you thought you were changing.) Self-consistency can present a huge problem for storytellers. After all, what's the fun of going to the past if there's no possibility of changing anything? It can be done (see bottom of post), but it's definitely a challenge. [Note: Self-consistency also creates problems that lead many/most physicists to believe that time travel is not possible in our universe. For instance, if a time traveler decides, as an experiment, to travel back in time by a year and cut down an insignificant tree that was grown and protected for this purpose, and was standing when they left, how is it that they just happen to not cut it down?] One potential danger with self-consistency: Multiple solutions. For instance, consider the following two scenarios: 1. A character is attacked by robbers and dies. 2. A character is attacked by robbers and is saved by a mysterious stranger, who later turns out to be that same character returned from the future. Both 1 and 2 are completely consistent with your world's internal logic. The trouble is that a solution (or "bootstrap paradox") like 2 can be manufactured to get your character out of almost any situation; it's basically a "get out of jail free" card that you as author can use any time you write yourself into a corner. If you use this device once a few readers will be slightly bothered by it. If you use the device often your readers will know that any situation can be resolved that way, and they may lose interest in your story. **Other forms of time travel** The usual alternative to self-consistent time travel is alternate universes. In this approach, your characters discover or create a portal/wormhole to the past, where they are able to change the timeline. The problem (which many stories ignore) is that if they travel back to their own time, they will find that nothing has changed -- the past they were changing was not their own, but the past in an alternate universe. If you don't want to deal with this, you could find some excuse to make the trip to the past a one-way trip. But note: if you create both ends of the wormhole in the same universe, they're going to stay in the same universe. So you can't use the technique described in the Thorne thought experiment. (Also, note that a discovered/created wormhole certainly *could* have both ends in the same universe if you're willing to deal with self-consistency.) **Fudge the laws of physics** The two scenarios above are quite constraining on a story, so many writers have decided to just fudge the laws of physics. If you take this route, your best bet is to come up with some reasonably self-consistent rules about who gets to remember what and how communication works between different "timezones", and stick to these rules. A couple key details that need to be worked out: 1. What happens if someone kills their own grandfather, or tries? (Do they return to their own timeline and find that no one remembers them? If so, they should be able to remember how the timeline "used to be" even once they've changed it, and people who did not time travel will remember things differently.) 2. Can someone in the past interact with someone in the present (e.g., by sending messages)? If so, what does it look like when the past is changed? Does a new dent suddenly appear in the car while the present person watches, or does the person in the present believe the dent has always been there? [Note that if you're not fudging the laws of physics, one of two things happens: either the past is never changed (self-consistency) or changing the past does not affect the present at all (alternate universes).] --- **Side note: Self-consistency story arc examples** Here are a few story arcs I've seen that did not violate self-consistency. * A character does not know/believe/accept that the past cannot be changed. They journey back in order to change it. But somehow or other they don't. You can be creative about why not, but there are a couple of "twists" that have proven especially poignant if done well: + They end up causing the very thing they were trying to stop. (This is a classic.) + They decide not to change the timeline after all. This can be due to personal growth, new knowledge (that volcano eruption was necessary to stop an alien species from invading earth), or some combination. * A character, having gone back in time, seems to change things, because they were mistaken about how things went the first time. Surprisingly, *Harry Potter and the Prisoner of Azkaban* handles this quite well in spite of ignoring just about every other aspect of physics. (But note that the Harry Potter book does suffer slightly from a bootstrap paradox.) [Answer] Since you were asking about wormholes and the analysis by physicist Kip Thorne, I'll assume you were asking about what would *theoretically* be true in Einstein's theory of [general relativity](https://en.wikipedia.org/wiki/General_relativity), which mathematically allows for the possibility of [traversable wormholes](https://en.wikipedia.org/wiki/Wormhole#Traversable_wormholes) like this, and which Kip Thorne based his analysis on (he also showed that, contrary to some other answers, this needn't lead to any time travel paradoxes, see my answer [here](https://scifi.stackexchange.com/a/78787/22250) for details, along with [this answer](https://scifi.stackexchange.com/a/78864/22250) where I give a more conceptual way of thinking about self-consistent time travel involving a hypothetical computer simulation). Thorne used general relativity to calculate how things would work if one mouth of a wormhole was taken on a high speed round trip away from Earth and back, while the other remained on Earth. He describes the results of the calculations, and a thought-experiment involving him and his wife Carolee, starting on p. 502 of his book *Black Holes and Time Warps*: > > The laws of general relativity predict, unequivocally, the flow of time at the two mouths, and they predict, unequivocally, that the two time flows will be *the same* when compared through the wormhole, but will be *different* when compared outside the wormhole. Time, in this sense, hooks up to itself differently through the wormhole than through the external Universe, when the two mouths are moving relative to each other. > > > And this difference of hookup, I then realized, implies that *from a single wormhole, an infinitely advanced civilization can make a time machine.* There is no need for two wormholes. How? Easy, if you are infinitely advanced. > > > To explain how, I shall describe a thought experiment in which we humans are infinitely advanced beings. Carolee and I find a very short wormhole, and put one of its mouths in the living room of our home and the other in our family spacecraft, outside on the front lawn. > > > Now, as this thought experiment will show, the manner in which time is hooked up through any wormhole actually depends on the wormhole's past history. For simplicity, I shall assume that when Carolee and I first acquire the wormhole, it has the simplest possible hookup of time: the same hookup through the wormhole's interior as through the external Universe. In other worlds, if I climb through the wormhole, Carolee, I, and everyone on Earth will agree that I emerge from the mouth in the spacecraft at essentially the same moment as I entered the mouth in the living room. > > > Having checked that time is, indeed, hooked up through the wormhole in this way, Carolee and I then make a plan: I will stay at home in our living room with the one mouth, while Carolee in our spacecraft takes the other mouth on a very high speed trip out into the Universe and back. Throughout the trip, we will hold hands through the wormhole; see Figure 14.7. > > > Carolee departs at 9:00 A.M. on 1 January 2000, as measured by herself, by me, and by everybody else on Earth. Carolee zooms away from Earth at nearly the speed of light for 6 hours as measured by her own time; then she reverses course and zooms back, arriving on the front lawn 12 hours after her departure as measured by her own time. I hold hands with her and watch her through the wormhole throughout the trip, so obviously I agree, *while looking through the wormhole*, that she has returned after just 12 hours, at 9:00 P.M. on 1 January 2000. Looking through the wormhole at 9:00 P.M., I can see not only Carolee; I can also see, behind her, our front lawn and our house. > > > Then, at 9:01 P.M., I turn and look out the window-- and there I see an empty front lawn. The spaceship is not there; Carolee and the other wormhole mouth are not there. Instead, if I had a good enough telescope pointed out the window, I would see Carolee's spaceship flying away from Earth on its outbound journey, a journey that as measured on Earth, *looking through the external Universe*, will require 10 years. [This is the standard "twins paradox"; the high-speed "twin" who goes out and comes back (Carolee) measures a time lapse of only 12 hours, while the "twin" who stays behind on Earth (me) must wait 10 years for the trip to be completed.] > > > I then go about my daily routine of life. For day after day, month after month, year after year, I carry on with life, waiting--until finally, on 1 January 2010, Carolee returns from her journey and lands on the front lawn. I go out to meet her, and find, as expected, that she has aged 12 hours, not 10 years. She is sitting there in the spaceship, her hand thrust into the wormhole mouth, holding hands with somebody. I stand behind her, look into the mouth, and see that the person whose hand she holds is myself, 10 years younger, sitting in our living room on 1 January 2000. The wormhole has become a time machine. If I now (on 1 January 2010) climb into the wormhole mouth in the spaceship, I will emerge through the other mouth in our living room on 1 January 2000, and there I will meet my younger self. Similarly, if my younger self climbs into the mouth in the living room on 1 January 2000, he will emerge from the mouth in the spaceship on 1 January 2010. Travel through the wormhole in one direction takes me backward 10 years in time; travel in the other direction takes me 10 years forward. > > > Thorne's thought experiment is basically identical to your own aside from the dates being different, so it's clear what the answer should be according to general relativity. If B's clock reads 2004 while A's clock reads 2012 *as seen externally*, time must "hook through" the wormhole differently, such that the clocks remain synchronized when someone looks through the wormhole, or makes a short trip through it. Thus if you look through mouth B when its clock reads 2004, you should see the clock next to mouth A when it also reads 2004, and if you then step into mouth B and exit mouth A, you will actually find yourself on Earth in 2004. ]
[Question] [ A K3 civilization is a civilization that has access to the amount of power generated by a galaxy. Such a civilization would span 100s of galaxies. How can it exist as one entity if it takes thousands of years to travel from one side to the other, if you were going at light speed, without falling apart because of it being almost impossible to control an empire where if you want to create a new law or make an announcement people at the border would hear it thousands of years later? [Answer] The hard part about exploring K3 civilizations is that you have to start thinking differently. Radically differently. It should be no surprise that social structures that function on a an utterly insignificant little blue green planet orbiting a small unregarded yellow sun far out in the uncharted backwaters of the unfashionable end of the western spiral arm of the Milky Way Galaxy don't function so well spanning galaxies. From your question, it looks like we are assuming faster than light travel. You say 100s of galaxies, and thousands of years. Our nearest galaxy is 2.5 *million* light years away, so it looks like you're assuming that travel is perhaps a thousand times faster than light. I wont sweat the details. It just means I will focus on your "thousands of years" quote. If you indeed wanted to have only light-speed travel, the process is the same, only the numbers are much bigger and you have to start to consider things like the death of stars into your empire plan. The actual amount of time is actually not the important part. What matters is the dynamic range. It's easy to rule a mountain of granite with thousand-year round trips. Granite doesn't change much in a thousand years. It's much harder to rule a small patch of the Amazon. The creatures in that plot might change on a minute-by-minute basis! We're actually pretty familiar with having tremendous control over things when there's huge time scales. Consider [these guys](https://www.youtube.com/watch?v=MdTS6-fbNH0). Main Street is a wonderfully entertaining barbershop quartet. Now I'll note that one of the defining characteristics of a good barbershop quartet is the "angel's voice." This is an illusionary voice that only appears if the four singers are *perfectly* in tune. They obviously have some astonishingly tight control over their voice. But what does that really mean? If we want to look at timescales, we're first going to have to identify what matters. Here's a first step: [what the vocal chords look like](https://www.youtube.com/watch?v=-XGds2GAvGQ) while singing. It's a bit freaky looking. But what happens when we look at them at a different timescale? If we look at [the vocal chords at a few thousand frames per second](https://www.youtube.com/watch?v=9kHdhbEnhoA), we get a very different image. It looks almost uncontrolled. You can see countless points in time where very localized physics causes the vocal chords to separate in slightly different ways. You can see the cascades of energy rippling outwards to be damped by the muscles surrounding the vocal chords. You can see the awkward moment where the voice breaks, switching between registers. So how do we reconcile these two images? The secret is that we humans are willing to let a lot of unpredictable things *just happen*, as long as we can, over time, stabilize the things we want to see. Our vocal muscles stabilize the frequencies of the beats of the vocal chords. Our lower brain then stabilizes the muscle tone of those vocal muscles in order to maintain a pitch. Our upper brain then controls the stability of this muscle control to portray things like emotion in our singing. Finally, we try to use that emotion to stabilize a feeling in someone else, in our audience. A K3 civilization would have to think like this, but on a much grander scale. It would need to have a soft but firm centralized rule that strives to stabilize the most important aspects of their rule of the empire on a timescale of many thousands of years. They would rule like the captain of the Titanic. No quick movements. Just slow steady dependable adjustments. They would need to stabilize individuals and ideas which seek to create stability themselves, but on a more local scale, under the rule of the galactic empires. Those individuals and their ideas should stabilize the next generation of faster moving individuals, and so on and so forth. If a disruption occurs (and it surely will), the local "government" forces should divide the disruptions effects into different time scales. Anything which is on a timescale faster than a round-trip to the next level of government should be handled their way, on their turf. Anything higher than that should be handled in a way which gives the next layer an opportunity to act. Basically, they should take the rough edges off of the disruption, and turn it into a nice soft pitch that the next layer can hit out of the park. The only issues that reach the centralized government should be the slow ones that you can afford to spend perhaps a hundred thousand years to debate on and react to. Done correctly, it's almost seamless. It looks like one solid indivisible entity, when it's really far more complex and beautiful. [And beautiful it can be](https://www.youtube.com/watch?v=SBenttZUT7A). [Answer] The huge civilization would be governed by the Governor, an artificial intelligence program. There is not one Governor: there are many copies, distributed through the civilization. More can be made on demand. The Governor is not updated. Each identical copy of the Governor governs its region by applying built-in principles and algorithms. Thus, although there is not one law that applies to the entire civilization as an entity, the laws one finds in place to place are very similar, having arisen from the Governor's inherent principles as applied to the local situation. This would be similar to the idea of a Constitution describing how government should take place, with local regions applying as they saw fit. Except in this case there would not be squirrely locals bending the intent of the Constitution to serve their interests: the Governor's only interest is the stability of the civilization, and it impartially rules according to its principles. An optimal constitution is like an optimal body plan: the shape of the cockroach and shark deviate little over the millennia. The Governors do not communicate with each other because there is no need. They do not learn or adapt; they are not amended. This leads to less flexibility as regards government, although the set of principles is turned into law according to local circumstances, and these implementations can themselves be flexible as circumstances warrant. It also leads to stability and consistency across the civilization. [Answer] The sheer closest I can fathom for an empire limited by the speed of light is the Qeng Ho from [*A Deepness in the Sky*](https://en.m.wikipedia.org/wiki/A_Deepness_in_the_Sky). And I swear I've writtenabout them on WB (or atleast on SE somewhere) before, but I can't find it. [A few other people have](https://worldbuilding.stackexchange.com/search?q="Deepness+in+the+sky") with regards to a few topics. The Qeng Ho weren't an empire as such, but a loose collection of disparate groups that all held the same ideals and goals; essentially a societal norm spread across light-centuries. These groups would fly between known civilized worlds and trade in whatever might be of value. Sometimes it would be technology, or it might be goods, or it could be information. Occasionally they would arrive and find the planet having bombed itself back to the stone age and the Qeng Ho would aid in rebuilding a space faring society because they knew that in 100 or 200 years another Qeng Ho ship (them or someone else) would be by again and the planet would have valuable trade once more. The backbone of what made them functional was--effectively--a galactic radio station. Every Qeng Ho ship would broadcast an automated signal that would contain the blueprints necessary to go from radio ("are you recieving? Build this...") to intra-solar space travel. As well as things like language and the society of the Qeng Ho themselves, so that when the traders showed up, they could parley with minimal effort. Underlying that was a private Qeng Ho encrypted channel that allowed groups to talk with each other. Not quickly, but still faster than their ships could travel. They'd use this channel to broadcast locations of new civilized worlds, premium technical advancements (the Qeng Ho kept the best stuff to themselves), and so forth. They knew that any given message may never be received, much less generate a reply that they would hear in their lifetimes (even long as they were due to relativistic time dilation and life prolonging technologies). But I wouldn't call them a K3 civilization, necessarily... Just the closest thing to "a galaxy-sized society limited by the speed of light" that I am aware of. And I'm not 100% sure that this would truly work, but it is plausible enough for a novel. [Answer] # It would never form in the first place Going off of HDE226868's comment, unless there is a way it was formed under such conditions, then it is unreasonable to expect it to be maintained that way. Given the rate of technological development and lifespan of our own species, there is no reason to expect that the expanders of a far-flung empire would still hold allegiance to a polity they left dozens or hundreds of lifetimes ago, can't communicate with, and could be thousands of years technologically an culturally divergent at this point. Now, if you want us to assume that some different sent of conditions of lifespan and rate of technological development, perhaps the answer will change, but then that would be a different question. [Answer] You honestly couldn't if you were restrained by light speed, but you could maintain one buy having them form a sort of state like government like in Greece, but he leader title would be mostly honorary and not be very powerful [Answer] Unless you can travel faster than light, there is absolutely no reason why a planet would follow the laws of a central government. If you rebelled, nobody is going to turn up and stop you for a thousand years which makes a central government pointless. Tax can't work when it takes several lifetimes to arrive. Same with trade. Same with communication. Without faster than speed of light travel, government won't extend past a solar system at best and more than likely be just a single planet. People will still get on generational ships and colonize new planets but they'll make their own laws. ]
[Question] [ There is a walled town, situated at a river ford, which maintains a militia of ~350 for a regional population of ~1000 farmers, rivermen, minor estates, townsfolk etc. I feel that I'm getting the hang of some of the logistics, but when it comes to horses I'm stumped. Basically I'm wondering how many horses it would be fairly efficient/flexible to have on hand for this militia. **VERBOSITY ALERT**: for the rough-estimate-breakdown, please just skip over all the excuse-making to the last bullet, "So at a guess, . . ." So far: * this is allodial land; no local resource or other duty is owed outside the region. * the 350 out of 1000 is based on a rough estimate of population distribution in which the total of able-bodied females and males, eligible from ages 15 through 35, hovers around 400 ... minus ~44 pregnancies and parents exempted while caring for children under 5 (~90 of those), minus another ~6 citizens wealthy + preoccupied enough to pay to not-'play'. (these last are each taxed the equivalent of the council's expenses for a member.) Only about 300 of the 1000 live within the town walls. * on average, in peacetime, about a tenth of the militia is on duty each day; each member owes 3 days of guarding (street patrols and/or wall watch) and at least 1 of training per month. Presumably, horses are not particularly useful to whomever is on wall duty. I started thinking about 15 on the wall, 15 in the streets, and the least experienced doing go-fer/messenger stuff, but then thinking about trade escorts, scouts, and outlying territory, that's when I got stuck on the horse thing. * irregular duties include light escort of trade caravans passing through the region. Activity of bandits, monsters or other hostiles isn't frequent but isn't predictable either, so most caravans will already have hired some of their own muscle. * forest has been cleared for several hundred miles in every direction, but the land under militia protection can be assumed self-sustaining in matters of wood as well as food/feed. ~20 small estates spread out past the opposite banks of the river and further 'down-road'. The largest city on the continent, pop. over 100,000, is ~3 days' ride from town, directly away from the rest of the lands under militia protection. OTOH it would take ~5 days to ride the other way down the highway and out of militia 'jurisdiction'. * magic is close to standard AD&D - main subtypes arcane/divine, etc. but arcane is a rarefied pursuit and if the odd militia member is 'wizardy' their primary functions would be artillery and/or fortification. * local religion isn't preoccupied with horses beyond their agricultural utility; low-level cleric-types may be peripherally involved in the stables, but the council doesn't ensure divinely-fueled equine care. If a member is slain in the line of duty (s)he will be brought back from death by a high priest (only one locally available) at council expense if possible, but a member who loses a horse is responsible for replacing it. * historically there has not yet been a reason to field the entire militia simultaneously, outside the walls + mounted. Invasions and raids do happen, though not like clockwork, and each hamlet and estate in the region has a small fortified townhouse and its own stable(s), but the general idea with any large-scale threat is for all 1000 citizens to take refuge within the town walls. (Might have to enlarge the town itself to account for emergency stabling ...) * So at a guess, on any given day (at least in an 'averaged out' sense) there are ~20 horses in militia use in/around town, plus a few more at each outlying manor, a few running messages or other militia business between 'stations', maybe a few escorting a caravan, a few being used to train new recruits ... So if this means close to 100 horses in day-to-day circulation, how many more might be on hand to accommodate occasions like emergency evacuations, or keeping a 'fresh' reserve for rapid communication or surveillance? [Answer] 350 militiamen out of 1000 people seems to be a bit too much. I checked some data for [Cossacks](https://www.wikiwand.com/en/Cossacks), semi-militarised groups that used to live on the borders of the Russian Empire, and despite mandatory military service (20 years: 3 years training; 4 — active duty; 8 — special duty (can go home more often, lighter duty); 5 — active reserve), only 1 in 10 was considered fit for duty. --- You can actually use Cossacks as a guide for your own world. They comprised the bulk of Russian light cavalry for centuries. They also started as local 'militias'. Each Cossack was expected to bring their own gear, clothing, and a horse(s) when summoned. The government only provided ammunition and later some salary. In addition to salary and war spoils, Cossacks were granted tax breaks, trade privileges, and a special social status similar to minor gentry. According to the 1869 law, each Cossack (every person, not just military) was given 30 [hectares](https://www.wikiwand.com/en/Hectare) of land. However, it was never realised in practice. In 1916, 4.4 mln Cossacks had about 62 mln ha of land they could work (ownership of land in the Russian Empire was a very complex topic beyond the scope of this question). About 80% of this land is very fertile and was used in agriculture and animal husbandry. The staple crop was wheat, as it is relatively easy to grow and does not disrupt military training that all Cossacks were obliged to participate in. Hunting, fishing, and trade were also highly popular occupations (and the only ones allowed prior to the beginning of the 18th century). Since many able-bodied males were busy, agriculture, crafts, and industries were not very well developed. Many towns and villages depended on food bought elsewhere using money earned through trade (that's where those tax breaks came in handy) or war spoils (including ransom money). There are a lot of historic documents mentioning poor state of homesteads and difficulties associated with the absence of men. Women, being busy with children, gardens, small animals (pigs, sheep, etc.) and chickens, often had no time to work the land. If a family could not hire at least some seasonal help they could starve. --- Going back to your story... You will need at least 700 war horses (ready for battle; the herd will be much bigger). You will also need [draught horses](https://www.horsejournals.com/popular/history-heritage/history-draft-horse-muscle-men-horse-world) for agriculture, transportation, logging, mining, etc. The number of draught animals (horses, mules, oxen) per farm depends on your period and agricultural practices. To give you some reference point, in the 17th century rich farmers in England had about 7-8 working animals, which were used by tenants to do all necessary works. Horses eat about 1.5% of their body weight a day. About 1 ha of pasture is sufficient to sustain one horse for a year. Herds may require a bit less land with proper management and some migrations to avoid overgrazing. You might also want to dedicate some land to grow hay and grain for winter and war. I will let you do the maths, but it looks like your people will be very busy just providing for animals. I would suggest to increase the overall population or to reduce the number of horsemen in your militia. --- A small bonus :) : [an interesting link](https://www.thoughtco.com/history-of-american-agriculture-farm-machinery-4074385) detailing a number of hours required in 18th, 19th, and 20th centuries to produce a certain amount of corn and wheat. [Answer] # Horses are expensive and most people don't have the space or income to support one. Alongside that, a militia as opposed to a standing professional army, have to supply their own kit. * Farmers will have a couple of (heavy) horses to plough the land and pull the cart to market. A group of poor farmers might have a pair of heavy horses between them. * A gentleman would have a (light) horse, as would his lady. * A man who considered himself to be a gentleman but didn't have the income for it might have a horse or he might rent one as needed. Townsfolk, carpenters, tailors etc. would not have horses. Nor would labourers, domestic servants or otherwise. There aren't in practice a lot of horses around. The militia would fight on foot. [Answer] That was a really long (really long) question. Let me narrow this down: If your society has the wealth to support it... * 350 horses such that all 350 men can be called upon if needed. * 350 remounts such that wounded/killed horses can be quickly replaced during battle. * At a guess... 30 horses for transporting equipment and supplies when the troop needs to travel. That's 730 horses (exluding the horses needed for "normal upkeep," like importing food into the troop, but those are usually owned by the farmers, etc. bringing the food). Many ancient societies couldn't afford that kind of luxury. Even the [early Roman cavalry](https://www.ancient.eu/Roman_Cavalry/) had just one horse per man. Battlefield medical for the horses was important. **You never want less than one horse per man. Horses often die faster than riders because it's too easy to hit the horse.** Which is why medieval [heavy calvary](https://en.wikipedia.org/wiki/Heavy_cavalry) sometimes had the (poor) horse wearing ear-to-ankle armor (the armor being cheaper to maintain than one or more additional horses). [Answer] There will likely be a small core of permanent military staff, to lead in battle, to work out duty roster, to write up and apply for a budget, etc. This core could include a small staff to maintain the horses permanently assigned to the militia for various tasks. Each horse will require a certain amount of space for stabling and/ or grazing, along with storage for feed and people to take care of them. Since the majority of the town's people live outside the town, their occupations are likely to be largely focused on agriculture, logging or mining and so on - all occupations where horses would be useful, if not entirely necessary. Have your town subsidize such horses and their upkeep, which will serve the purpose of increasing productivity - necessary when each worker loses at least four working days every month. If you are using a six working days and one day off, seven day week, thirty day month, each militia member loses 15% of their productive time to this service. Furthermore, the militia are then mounted and are able to mobilize more easily should it be needed. Mounted militia also serve as passive scouts - likely the first to be aware of trouble brewing around their locale, and able to then quickly bring word of possible battle to the town as soon as possible. Now I know that draft horses and riding horses are not neccesarily the same, but I'm guessing draft horses can be ridden in a pinch. Also, dispersed horses will aid in getting the scattered townsfolk to safety as quickly as possible. Using this method, it should be fairly easy to support one or more horses per militia person. ]
[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/97390/edit). Closed 6 years ago. [Improve this question](/posts/97390/edit) [Other question](https://worldbuilding.stackexchange.com/questions/13531/what-would-be-the-development-of-the-most-valuable-irreplaceable-food-trade-goo) concentrate on most valuable goods but most of good listed would involve local trade - for example alcohol can be easily produced with modern knowledge anywhere (see Prohibition in the USA). In similar way the livestock etc. The only things in answers to that question I saw for long-term traded goods would be salt and spices which cannot be produced locally without modern infrastructure. However I'm more interested with goods which would form a basis for new continental trade networks, like copper and zinc (in the Bronze Age), famous Silk Road and less famous Amber Road (I've seen some speculating about Jet Road being a source of caps being universal currency in *Fallout*). What goods would start traveling across Europe or across America when society collapses and starts rebuilding at level of city-states (with larger political entity here and there)? **EDIT** For purpose of this question please consider standard nuclear apocalypse with radiation glowing green and roaming bands of mutants. **EDIT 2** To clarify I'm looking for good which is a) valuable in such setting and b) decentralized. I don't think that ammunition or guns would be found in much larger quantity in east coast than west coast to make the trade route. On the other hand I don't think black pepper can be easily grown in North Canada. [Answer] **Information** Communications will have broken down so wandering minstrels and the like would make a comeback. Communities need to communicate before they can trade, you need to know what I can offer you and what I need before you set off for the long trip to my town. If it's post-nuke-apoc, then there's plenty of raw materials lying around in the ruined cities, so zinc and copper trading probably wouldn't take off. You'd need to be able to extract and refine it but almost every pre-apoc community would have had a library. **Services** So we have knowledge and raw materials. Now my community builds a smithy, and trains a couple of folks to use it. Let's say they make the best ploughshares in the area. Your community wants one but doesn't have the time or resources to train a smith and equip him, so they buy one from me. Supply meets demand, trade results. [Answer] It would depend on what level of transport infrastructure had been recovered. I suggest that the level of transport available in this world might be usefully matched to the level of transport available during any historical time period to find out what goods might be traded. It would also depend on the level of government. If there are city states then they should be able to provide protection for trading by supplying troops to protect against bandits and pirates. **Human only transport** If the only means of transport is by foot then it would only be practical to transport very high value items with very great difficulty. All food would have to be grown locally. This is a similar situation to that of the ancient Maya. **Sailing ships plus horses and carts** Coastal and riverine transport of almost any bulk materials such as stone, leather, pottery, worked metals, cloth and food stuffs are now possible. Away from the coast and rivers horses and cart can be used to transport significant amounts of materials, but food would probably still be grown locally where possible or in locations that are distant from the coast or river network. Materials can be traded over great distances using sea or even river transport, just think of what the Romans were capable of with grain transport from Egypt to Rome. **Mechanised transport** If steam power is available then the restriction on moving materials is relaxed further still and even areas distant from the river network and coasts can be reached by train. [Answer] ## Batteries! Although you haven't specified a particular apocalypse, since you mention radiation and aliens I'm going to assume this is an "aliens invade and we use nukes to fight them" kind of scenario. In this case, you'll have massive damage done to infrastructure and electrical grids, but you'll still have all the devices that need power to run- laptops, flashlights, water purification devices, etc. Batteries would be an enormously useful resource because they're semi-rechargeable, portable, and can be used for a huge number of situations. Also, they're already in pretty high demand- that'd only increase during an apocalypse. [Answer] Books. The ability to distribute information electronically is likely severed by nuclear EMP. So books will be key to rebuilding: physics, engineering, medical, obviously, but also entertainment. [Answer] **Manufactured goods.** You can get an idea of what settlers in the wilderness would need by looking at the things salvaged from the sunken steamboat Arabia. This was a steamboat that sank outside of Kansas City in 1856 and was preserved with its cargo in the deep mud. It was carrying goods for pioneers in the western territories. <http://1856.com/arabias-story/the-arabia-museum/> [![the Arabia museum](https://i.stack.imgur.com/CdpfK.jpg)](https://i.stack.imgur.com/CdpfK.jpg) I am impressed that nearly everything recovered from the wreck was manufactured goods: ceramic dishes, matches, metalware like forks and knives. Glassware. Loads of ax heads. Huge numbers of shoes and boots. Textiles. Also and not really manufactured goods: preserved and pickled fruits. Manufactured goods have always been trade items. Manufacturing is a way to add value to a small item. Manufacturing is centralized and the goods need to travel. Manufactured goods are usually not perishable. Textiles were traded at great distances across the ancient world and ever since - silk is the example you read about but Indian cotton has been recovered from ancient tombs in Mongolia. Porcelain came great distances from China and the same for Roman glassware. Iron tools were and still are valued trade items - iron plows, knives and axe heads are so much better than wooden or stone tools but you cannot really make your own iron on the farm. Your places where civilization has come back to some degree would be centers for manufacturing and trade routes would exist to carry materials to outlying areas. Don't forget your outlying areas need to have something nonperishable and of worth for the traders to bring back: e.g. scavenged relics, furs, whiskey, marijuana, tobacco, slaves. [Answer] **Salt** It can only be gained from salt deposits or from saltwater (assuming that all your local supermarkets have long been looted dry). However, it is very important in a low-tech world for food preservation. **Animal products** I'm assuming in your post-apocalyptic world humans have retreated to safe places, which means they probably cannot use open fields to rear animals, or not that many. But nature will survive and localized places will produce different species who survive the apocalypse with the help of certain mutations. It is likely that your humans will hunt them and there will be different animals surviving in different locations. Some will have thick pelts, some will have hard bones which can be carved into implements, some will have other useful parts, like stomachs of ruminants for cheese making, musk glands, horns and hoofs for gelatin, feathers for pillows, and whatever else. **Geiger-counters** Not many people today would be able to manufacture one, so it is likely that not many will have retained the knowledge in the future, and people who make them won't just give away the secret. Also, they would probably need specific technology from pre-apocalyptic installments, which probably wouldn't be very portable. [Answer] The currency of the world in any post apocalypse is commonly known as "Lead Bullion" aka rounds of ammunition because in the absence of society and laws he who can enforce his own laws survives. **EDIT:** apparently it appears there is a common knowledge gap of a popular modern sub-culture. You should all look into [doomsday preppers](https://en.wikipedia.org/wiki/Doomsday_Preppers). For obvious reasons I am not going to cover the breadth of knowledge in doomsday prepping. Suffice it to say plenty of people have plans to make bullets in the event of any global disaster precisely because ammunition will be the currency of the land. It's why it's called lead "bullion" lead is a cheap toxic metal otherwise. [Answer] Luxury goods. The immediate concern a after a Apocalypse Is the are necessities (Food water clothing and so on ) Once that's taken care of people began looking for more Usually better clothes better food extra . Through out history most long distantrade trade has been based around luxury items Silk, Spices, Dyed clothing, Tobacco, Sugar And so on. I would expect that Once trade slowly starts up again these type of items would again become very valuable and make up most of the transatlantic trade . [Answer] Human resources. Guilds would prosper. Roving craftspeople would go from place to place, like the stone masons of old. I suspect they would primarily be technicians. Manpower would be at a premium, so I suspect there would be some form of slavery. Employee-employer contracts would be rare, as there would be insufficient resources for payment. If payment is in room and board food only, then that is pretty much servitude. I suspect slaves would not be bought and sold, as in a slave trade, it would be more like mutual dependency ('apprenticeship', for example). The economy would be a return to very early concepts - you sell what you directly produce. Individual entrepreneurial spirit. Individual proprietorship of all business, if you will. So one of the biggest trade commodities would be in manpower. ]
[Question] [ ## Can ice, without the use of major magic, be used as an effective, easy to produce weapon? On my story's fictional planet, overall technology level comparable to late medieval Europe, I have a nation that is living in an icy desert, surrounded by extremely tall mountains, leaving only one small passage to leave the area. The people have adapted to the harsh conditions (average temperature of −25° Celsius, not a whole lot of edible things to choose from). They are a peaceful bunch, never had they needed to defend themselves, as no-one dared to set foot into this incredibly awful place. Now they need to defend themselves though, as an Evil-Overlord-of-Doom-and-Destruction is coming. With thick fur-coats and enough food and water for his small, 3000 men army, that carries swords, bows and shields. a few important points about the soon-to-be-invaded ice-people: * they do have access to iron and stone to some extent. * they are completely self-sufficient, no need for imports from outside their land * they have some tools, mostly to prepare their food * they do not know how to make fire, only exception is in the next point * a few of them are capable of perform minor magic, such as tiny sparks and flames, levitating lightweight objects for short periods of time and so on * population: ~8.000 There will be a warning, prior to the invasion, so the people will have some time to prepare. Currently I am thinking about 2–3 weeks. But how should/can they prepare? **Can they use their abundance of ice to craft weapons or generally use the ice as a weapon? If not, are they basically doomed?** [Answer] ## Err.. Sort of... --- But I would recommend to use: ## Traps Since your country is on the defensive, I suggest going to a more defensive style of fighting. I don't know what do you mean by *weapons* made of ice. But since the magic powers are limited in your world, I don't know how **ice-smithing** (if such a thing exists), really works. Therefore, **Traps** would be perfect in this scenario. For instance, your people can make * **Pitfall traps** that are made from *thin sheet of ice* that utilize **Iron Spikes** or * **Ice spikes** in conjunction to pitfall traps * For indoors, **Stalactite style traps** - your people can cast their minor levitation skill to attach them to the ceiling and put some kind of trigger to release it * **Trap doors made of ice** (works like pitfall) - but manually triggered to open with help of levitation skill, or some minor fire skill, etc. * **Blizzard** - if your people can cast flame spells I assume they can also cast ice spells. I assume there's always snow in your country but if you could somehow make man-made blizzard it could also work. Edit: * **Avalanches** as @Nicolai suggested, could also be taken advantage of based on the terrain. I'll try to edit this post if I could think of more. [Answer] > > Can they use their abundance of ice to craft weapons or generally use the ice as a weapon? > > > In principle yes, with the stated average temperature ice should be a viable material to make weapons out of. Using their (limited) magic they should be able to directly form the ice (or use small fires to melt it into forms), so no restrictions there. If you want, you could implement this technique as part of their culture (usually applied to make art or something like this), which would explain how they can quickly turn to make weapons with it. Apart from a bigger conceptual problem, the main problems I see with ice as a weapon are: 1) Ice - while considerably strong and heavy - is still not stronger than iron, so your people do not get any advantage from this (though its still better than nothing). 2) Weapons completely made from ice, would start melting once held, unless you insulate the grip with leather or furs. Additionally the could break easily, which could be counteracted by encasing wooden cores into the ice weapons. Now to my bigger point: Why would your people even want to make weapons out of ice? Per your description, they never encountered war and usually rely on their tools for hunting. Without contact with other civilisations, I would even argue that they never before heard about weapons or even war. But even if they know war, there is no real incentive to make weapons and directly fight against an invader. Instead they really should take advantage of the territory of their homeland. Even if the enemy is prepared for the weather and not prone to the problems people [invading Russia](https://en.wikipedia.org/wiki/French_invasion_of_Russia) had, tall mountains are hard for any army to march through - even more so if its cold and icy. The enemy will have to pass narrow mountain passes or other points, well known to your people, just because the rest of the terrain is not suited to march through. It should be relatively easy to set ambushes and traps (I'd say avalanches) at these points. If time correctly your people can even separate the enemy army from their supplies, which will quickly end them in the cold. [Answer] The best way to use ice against this invaders is à la Game of Thrones: build an ice wall around your town. It doesn't need to be 300m tall and 50m thick. A simple 3 to 4 meter tall, half a meter thick would suffice. The invaders won't have enough wood to build ladders or make a fire big enough to melt it, it's too slippery to climb and with -25ºC you can pack and press snow against the inner side of the attacked point to automatically "heal" the wall and reinforce it. Then wait for them to starve. No matter how many food they carry with them, they don't know the place, don't know how to survive there and will start freezing to death soon. Russia is far less hostile than the environment you are describing and it has defeated the most powerful armies of the world with the help of General Winter. [Answer] Ice could be used like very brittle obsidian, but it would not make robust edges or weapons. Your people should do what Eskimo's Inuit etc,. did for weapons, use bone and antler if available and other animal products like teeth. If they hunt they should already have weapons of some sort. If they have a professional experienced army heading their way that is prepared for the terrain and conditions I would think they'd be better off investing in running shoes. Unless they are in mountainous terrain (where they would have an abundance of stone) guerrilla warfare is probably not a viable option. [Answer] Ice is too brittle and two slippery to effectively use as a melee weapon, however as Bwrites says, traps are definitely an option. [Answer] Like already said previously, ice weapons are not par with their iron ones, so there's no real incentive to go that direction. Building an ice wall is vulnerable to besiegers building a ramp over it in the same way. Traps may be a nice idea, but it's still not specific to the particular environment, but more to the correlation of forces sizes. Their only chance in victory probably lies with using the harsh environment to their benefit; General Winter as has been aptly noted. But how? *By dispersing themselves so that the invaders never find them to subdue them!* They disappear, in little groups and companies, as far away from their center of civilization (that the enemy will try to besiege and conquer) as possible. Then, with the help of the harsh environment, make the enemies' lives miserable and their conquest hollow. In the end, they will up and go, to cut their losses - because even if they wanted something from that inhospitable land, they'd need locals to get it. [Answer] They're DOOMED! A culture - less developed, less armed, less trained - has little hope of defense. The scenario you describe puts them at a significant disadvantage. However, as you describe, they are self sustained and there is "only one small passage to leave the area". Is this also the only entrance to access the area? If so, destroy the path! Use the ice to seal it - not just a wall but the entire path! Or depending on how the path lays, wait for the army to enter the path (or tunnel) and then seal it. ]
[Question] [ Let's say that my Verrisirs (see here for more info on them: [What factors would allow this caninoid species to evolve successfully?](https://worldbuilding.stackexchange.com/questions/79869/what-factors-would-allow-this-caninoid-species-to-evolve-successfully) ) have achieved space flight and have developed starfighters. I was wondering how they would develop such starfighters. Now, these fighters are similar to those used in Wing Commander, so there will be some space dogfighting (even though this isn't actually possible but I grew up on Star Wars so eh). Now, since the Verrisirs are digitigrade, they would have a different seating arrangement than we do: [![This is an example of what I'm talking about.](https://i.stack.imgur.com/hVStr.gif)](https://i.stack.imgur.com/hVStr.gif) As you can see, the legs are bent a bit to allow their legs room to move, so they can be able to control the pedals and the controls are made to be similar to a bicycle handles, whereas our controls consist of buttons and a joystick (to put it simply). This would mean the controls for a Verrisir fighter to be a bit confusing for a human to control. Now, the Verrisirs like high-speed thrills, so their fighters would lend towards speed, but they would use lasers and kinetic weapons. They're not stupid though, so they would have missiles and torpedoes, just not a lot. I thought about the Fulcrum and the Tomcat as an examples, but those are human man fighters. A good example I did find was this: <http://acecombat.wikia.com/wiki/CFA-44_Nosferatu> But again, this is human-made fighter. So, here's my question: what would the fighters of a caninoid species look like in terms of cockpit design and ergonomics and how would they operate? [Answer] Human fighter designs are based on centuries of human equipment design; the instruments are built based on our expectations to sense the world, their location based on our sight lines... even the position of the seat is based on our design as an ape. Throttles, levers, and buttons are all based on our long fingered hands. The cockpit of a Verrisir space fighter would be completely different than anything remotely human; unless, in the progress of becoming a space-age species they threw away most of the features that make a canid a canid. That's why most games and sci-fi movies that have furry crew people turn them into humans with a few animal features; they still have ape like hands and an ape-like body plan. So, with this in mind, how would a canid cockpit be like? **Sensors** We apes like big windows, and need all kinds of gadgetry to support our rather pedestrian senses. One thing you didn't touch on in the description of your species in the other question is their visual ACUITY. Cats and Dogs have better night vision than us, but their resolving capacity is much lower; they're rather nearsighted compared to us and, while they have a slightly wider angle of vision, the angle of vision which is highly resolving is narrower as well. So what we know is that these canids can see better overall in various light levels, but their resolving capacity is much lower. In addition, their hearing and smell is much better than ours. As stated in responses to your question, these critters would need some hefty computational capacity to be effective spacefighters as well; they would use computers to augment what they're bad at and utilize what they're good at. So... A Verrisir fighter cockpit would be designed in such a way that the Verrisir tends to stand on all four paws, in a pursuit posture. Instead of levers and buttons, the computer uses the relative pressure of each of the four paws and the angles of the ears and tail to "fly by wire" the spacecraft. Instead of big windows, cockpits are entirely enclosed with armor. A repeater screen/vr system is placed within the center of vision to give high fidelity views to the center of vision based on head angle. Around the edges of this viewscreen are "idiot lights;" where color, intensity, and location convey their messages instead of printed characters like apes would use. To augment the skills already belonging to this species, the tactical computer in the craft plots the location of all detectable objects (spacecraft, planets, asteroids, missiles) in 3D space, and presents an aural image to the canid's ears. Whereas an ape would be flailing their neck around to see an oncoming enemy, your Verrisir would hear it coming. Each signal would be identified by a fingerprint of frequencies, so that your canid doesn't need to look at an object to identify it's location or any other parameters about the object. (Yes, I just canonized loud spaceship engines in your universe. You're welcome.) The angle of the Verrisir's ears tell the computer how much information to place on the sound of the object. A planet in the distance may have a ringing sound, or a low frequency rumble which gets louder as you get closer, while an enemy fighter would make a warbling "engine noise," with the parameters of the noise telling you distance, speed, throttle position (maybe by pitch?), and various other parameters. The object being "focused on" by the Verrisir's ears would have all the data overlaid, while perhaps all other objects would only have one or two identifying characteristics. Note I'm not saying that the computer is rambling off facts and figures. I'm saying the computer simulates high-tech "prey" noises; the Verrisir is tracking the noise in space. Olfactory "hallucinations" would be part of the sensor package; each object would "smell" like the pilot flying the ship for identification; enemies would "smell like" enemies, gas giants would "smell like" the gasses that make up the atmosphere, etc. Again, while an ape would be squinting at a screen to read labels or yelling at their android copilot to repeat the information, a Verrisir identifies make and model of the craft by sound, identifies it's location by the "location" of the sound around it's head, and identifies the pilot by smell. A human would likely never successfully pilot this ship. We're not equipped with any of the right appendages at the right angles to fit into the void within the ship, and all the sensors are tuned to a predator with great sound and olfactory senses, but lacking our precise visual acuity. Should we find a way to jam ourselves into one, it would be a smelly, loud experience overwelming our brains with nonsense information which, in the mind of a Verrisir, feels right at home running on their planet and chasing down prey. [Answer] I'd do things differently. *seats* are terrible for starfighters. Human designs assume 2 usable limbs and being seated is actually not that good as far as gforces go While humans haven't really gone for prone positions in aircraft, it makes a lot of sense for a species that's fine being on all 4s [![enter image description here](https://i.stack.imgur.com/INJS8.png)](https://i.stack.imgur.com/INJS8.png) So essentially a well supported, strapped in prone pilot, taking advantage of those digigrade legs and front paws to pilot the aircraft almost like a bike. It might also make sense to 'loosely' strap down the pilot and use their whole body movements (tilting to roll) to control the aircraft. In babylon 5, the niall class fighters used a [prone pilot](http://babylon5.wikia.com/wiki/Nial_class_fighter) position I'd also consider overall tactics - rather than going for larger, air superiority fighters, something with similar design philosophies to a [star fury](http://babylon5.wikia.com/wiki/SA-23E_Mitchell-Hyundyne_Starfury) or the classic tie fighter. Relatively small, fast craft working in large numbers, rather than large ones (and both the fulcrum and tomcat are fairly large). Think aircraft more similar to the f16 or better yet the [Folland Gnat](https://en.wikipedia.org/wiki/Folland_Gnat) ]
[Question] [ I've been working on building a society for my story, but I've run into what I consider to be a significant problem. What are the different professions required to maintain a society of a technological level of ~1800? How much demand is there for these professions compared to each other? (Such as you need X amount of farmers as opposed to X amount of blacksmiths.) [Answer] Roughly, at around 1800, for a moderately fertile country such as England, you would need: * 20% of the population in agriculture (farmers and their families). * 25% of the population engaged in various manufacturing jobs or families of men engaged in manufacturing jobs (including blacksmiths, shoemakers, tailors, carpenters and also factory workers making thread, cloth, iron, bronze, machinery, glass etc.) * 15% of the population in domestic service (if we include women servants; keeping house was hard work before washing machines, vacuum cleaners, microwave ovens and fast-food restaurants). * 10% of the population engaged in commerce (retail shops were all the rage, there were very few large department shops and there were no nation-wide chains such as Wallmart or Carrefour). * 5% day labourers (10% with their wives and children). * 6% of the population would have independent financial means of be members of the families of financially independent men. Those are the people who engage in politics, run for members of parliament, pursue scientific research and so on. * All other occupations and professions would be rare. There are very few civil servants, social workers, soldiers, sailors, lawyers, doctors etc. For real numbers you cannot beat [A Vision of Britain](http://www.visionofbritain.org.uk), which offers (among other delicious treats) synthetic tables extracted from the [historical census returns](http://www.visionofbritain.org.uk/census/). For example, for the [1841 census](http://www.visionofbritain.org.uk/census/1841) (numbers for England and Wales, occasionally rounded): * 16.5% percent of the population were engaged in *commerce, trade, and manufacture*. * 7.9% percent of the population were engaged in *agriculture*, of which: + 20% were *farmers and graziers*. + 76% were *agricultural labourers*. + 4% were *gardeners*, *nurserymen* and *florists*. * 4.2% were *labourers*. * 0.3% were *military* (meaning land forces) and 0.6% were *naval*. If Scotland is included, those numers climb to 0.7% land forces and 1.2% naval. * 0.3% were *professional persons* (that is, engaged in liberal professions, such as medical doctors, lawyers, professors, or architects). * 0.8% were *other educated persons following miscellaneous pursuits*. * 0.1% were engaged in *government and civil service* (the past is a very foreign country, isn't it). * 0.1% were *parochial, town, and church officers*, including *police* and *law-officers*. * 6.3% were *domestic servants*. * 2.8% were *independent* (or as we would say today, rentiers, people who have sufficient independent income from property or investment). * 1.1% were *almspeople, pensioners, paupers, lunatics, and prisoners*. * In total, the preceding *occupations* represent 41% of the population, leaving a *residue* of 59% of population not engaged in an occupation (which corresponds nicely with about 50% of the population being children and married women). Note that at that time England was the world's leading exporter of manufactured goods; England had also the world's largest merchant marine. In other countries the percentage of people engaged in making manufactured goods and in trade would be smaller or much smaller. In countries which were large exportes of agricultural products (such as Hungary or Wallachia) the percentage of people engaged in agriculture would be considerably higher. In general, countries participate in international trade, and the occupations of their inhabitants depend not only on the level of development but also on what each country exports and imports; in the time frame of interest, England specialized in exporting manufactured goods, and imported staple foods, which means that the number of people engaged in industry was higher than the average developed country, and the number of people engaged in agriculture was lower. Socio-political structure and culture are also important. [Answer] 1800 tech level is quite loose definition. It can be anything from hunting-gathering tribes in South-America to England in the early industrial revolution. I will chose the latter, and rely heavily on this link: <https://en.wikipedia.org/wiki/Social_history_of_England#Georgian_society> England's population was about 8 million at the time **36% of your people will still be farmers and their families.** **Another 36% will be rural non-farmer.** This includes a lot of things: Priests, teachers, medics , blacksmiths and coopers and potters, traders, landed gentry, majors... I think one priest and medic per 100 people should be more than enough for the period. From craftsmen you will need somewhat higher density, but these numbers depend on the sizes of the avarage settlements. If the villages are small, you need more blacksmiths to get everybody's horses iron-shod. Same holds for majors and local judges. And you need quite a lot of traders, to carry the products of the country into the cities, and then sell the goods of industry on the land. **The remaining 28% is the urban population.** * You need one king and some royal family members. * You need some bishops and other high-ranked clerics. * You need some thousands soldiers and naval sailors. * Some thousands of officials for public administration: from ministers to country tax collectors. * Some thousand businessmen: bankers, merchants and factory owners. * Some thousands of engineers, and some hundreds of scientist and university professors. * Tens of thousands of lawyers and medics and priest and teachers again. * The remaining will be workers, sailors, craftsmen, tailors and hairdressers, shopkeepers, and the sinewies of those. * Policemen and criminals are also unavoidable. Of course, one (a communist for example) can argue, whether bankers and factory owners and priests are actually needed, but I think, that to have a specific 1800 tech level, you need a quite similar society. (for example, with no capitalism, you probably won't get India-going sailing ships.) ]
[Question] [ So I'm wondering if a human civilization or a group of civilizations that evolved on an Earth-like planet comprised exclusively of islands no bigger than 500,000 km^2 (most of them would be smaller, though) and covering no more than 5% of the planet's surface would have population limits different than those of Earth. Obviously, the population could never grow as big as that of Earth, since there's much less land (again, 5% of the total surface area), but would the fact that all of this land is islands inhibit the population growth even more, or would it not make a difference? In short, would an all-island Earth-like planet impose any unique population barriers to humans? Again, assume the planet is Earth-like in basically every way, save the decrease in surface landmass. [Answer] You've told us that islands are "no bigger than 500,000 km^2". I checked Wikipedia, and that's actually fairly large. California is 423,970 km^2. Hawaii (the state) has an area of 16,635 km^2. The thing to think about is: most (though not all) of our major population centers are *right on the coastline*. Being on the water is good for trade, and it's a good source of food if you have fishing boats. The world you're building is practically all coastline, so I would think it would have a decent population density. Hawaii (the state) has a population density of 211 people-per-square-mile, compared to 84 people-per-square-mile for the United States overall. There are things to think about, certainly. You don't get big rivers when you're on an island, which means you have to think more about fresh water. When you're relying on fish for most of your food supply, overfishing can be a hazard. And technology doesn't grow as quickly if you don't have good mineral mines. But overall I think the world can sustain a decent sized population. [Answer] Polynesia had ongoing population problems, they were solved by emigration, endemic warfare, blood feuds and in times of drought cannibalism which in some places was formalised. Warfare became a part of everyday life, all men were trained warriors and sudden death was a constant threat. Genocide was not unknown although not normal, but whole districts were known to have been totally depopulated. Whole tribes became extinct in the larger Islands. Some small Polynesian islands lost their whole population due to lack of resources when interisland trade collapsed due to warfare on other islands. Micronesia there are tiny islands which could not survive population pressures without trade, and some practiced infanticide and/or killing mothers to prevent them having more kids (according to legends). So population can be managed, but it's not pretty. Polynesia still has population problems which are now solved by poor health care and bad food being dumped there, rampant obesity and emigration. But if for some reason they were once again isolated, it would in short order become a deadly struggle over resources again I would posit. One other issue no one has touched is there is no continental land, this means that some resources are actually pretty scarce in most places in terms of minerals, metals and things like that, you can have lots of trees with none really suited to building on a particular Island, this is how it works on earth anyway. Most of Micronesia, Melanesia (not so much since some of that is ex-continental) and Polynesia have this problem which was partially solved by trade and by replacing the native flora with imports, most of their staple foods in terms of plants were imported. Very few are native to the Islands. Take away just a few like taro, yams and breadfruit, and humans can't survive in any great number. Coconuts can survive a sea journey on their own for about three months, but none of the others can. So you need an equivalent of those for a start. [Answer] The [carrying capacity](https://en.wikipedia.org/wiki/Carrying_capacity) of Earth is hard to guesstimate. Historically, before the development of artificial fertilizers and the [green revolution](https://en.wikipedia.org/wiki/Green_Revolution) which increased agricultural output severalfold, it was estimated at ridiculously low values (see [Malthusianism](https://en.wikipedia.org/wiki/Malthusianism)); modern estimates may be as high as 40 billion people -- which will probably never be tested, as current [projections](https://en.wikipedia.org/wiki/Projections_of_population_growth) indicate a maximum of about 10 billion people by 2075, followed by a steady slow decline. About 1/3 to 1/2 of Earth's land is utterly unsuitable for agriculture; anyway, at present cultivated land represents [about 12% of Earth's total land area](https://en.wikipedia.org/wiki/Land_use_statistics_by_country). Your world has about 1/6 of the land area of Earth; depending on how fertile the land is, how much fresh water is available etc. that world may sustain a population comparable to ours, or it may not. I think that you can safely assume that 1 billion people is achievable. [Answer] Polynesia did alright, once they figure out boats expect a population boom. Obviously quite likely followed by mass death as some expeditions will run out of food. What they need is local food and a decent chance of getting from Island to Island. So no large storms, plenty of wood etc. edit: on the subject of storms. Storms are destructive. Storms would wreck your boats and likely any wooden buildings. Perhaps this would force them to develop masonry sooner. Tropical storms are nasty business. So I see that slowing down their progress as they go through cycles of destruction. Rebuilding is time wasted on not developing further. As your main goal seems rapid development. It could however foster a technological boom to survive the storms. But not without a cost. [Answer] Ok, I'm just going to list a few problems that come to mind for this scenario and how they could possibly be solved. Note: This is referring to the point in time that the civilization has outgrown the islands. ***Problem 1. Food*** I've heard of a thing called 'floating farms' <https://practicalaction.org/floating-gardens> which are basically crops grown on a floating platform on water... **IF** they figure out how to use that, especially over salt water, food would not be an overly large issue in population growth. Of course, you may need some defence against Storms & Waves - especially if you need to expand them further into the sea. ***Problem 2. Living space*** This depends on a multitude of factors, such as weather and oceanic problems that may arise from island living (though, on reflection, when has that ever stopped us?) If there are regions of very shallow water, then stilt-houses are a possibility. If not, one only really needs a large enough boat to live in, as long as there are ways to get food & clean water. ***Problem 3. Water*** Most humans get their water from freshwater sources, such as rivers, lakes, snow and springs. These will be limited to the islands. Unless some other way of easily getting water is available - maybe rainwater collection or evaporation & condensation- then it may be difficult for early civilizations to have enough to get off the ground. [Answer] The major limiting factor in this problem to me is the advancement of technology. Since our only comparison is Earth, you can see that population growth over our history was fairly linear and minimal until about the 17th - 18th century. The advancements in medicine, agriculture, transportation, etc all gave us the ability to increase the average rate of death. Therefore, if you assume that the population of the 'Island Earth' would be able to make the same strides in tech, then populating many small islands would not be an issue. I would think that many islands would eventually take on specific roles. For example, in one archipelago, you could have central island that the majority of the population lived. The surrounding islands could be used to support the center by being put into roles such as "agriculture islands", "mining islands", "manufacturing islands", etc. This would fit into some land use models that explain the separation of cities and towns. [Answer] Some Polynesian islands have practiced zero(ish) population growth. On small islands it is easy to see that your finite resources are best shared with limited numbers of people. If your people recognize this they may institute cultural norms that limit growth. However if you have larger islands who don't have to worry about it as much or you lose enough people to storms or wars there may be incentive to have more growth. ]
[Question] [ Now everyone agrees that when it comes to building orbital habitats, let alone a full-blown Dyson swarm with millions, maybe even billions of liveable habs in orbit around the Sun or the various planets, a certain amount of self-sufficiency is both required and inevitable, both in terms of resources and in the hab's local politics and methods of governance. Like nation-states, what's illegal in one hab may be accepted or even endorsed in another, and many fringe political or religious groups may choose to build small habs simply so they can express their own beliefs and live according to them away from persecution or prying eyes. However, while local governance is good and all for dealing with local problems, it must equally be agreed upon that some sort of diplomatic body, and preferably even a full-blown law enforcement/peace-keeping service, should exist to regulate how habs are allowed to interact with each other politically, economically, and in worst case scenarios, even militaristically. In order to effectively keep the peace between the habs, you'd need the swarm equivalent of Interpol and the UN to keep an eye on things like trade agreements, peace treaties and non-aggression pacts, and criminal activity against both citizens of different habs and against the habs themselves. Total anarchy is fine as long as it's contained to a few habs, but while a few lawless or deviant nations are acceptable when set against the larger swarm, the entire thing can't be allowed to be completely without laws or government or the whole thing will fall apart. You may be too far to easily enforce your will on the people of other habs, but you're still nowhere near far enough to escape the consequences of doing so. But if autonomy is the de facto state of orbiting habitats, then how would you effectively run such a system-spanning body of government and law enforcement, loose as it may or may not be? Alastair Reynolds provides a great example with Panoply and the Glitter Band in his book The Prefect, but I want to avoid ripping him off and even leaving that aside, I can still see a number of problems with his system of swarm governance (even if it is one of the best I've seen in fiction). Does anyone here have any ideas about what political models might work to loosely govern a large number of separate nation-states and how you might enforce it across a distance of multiple light-seconds or light-minutes? [Answer] I don't think that a Dyson swarm could be governed as a loose federation, cooperation or alliance of individual 'nations'. Since they are so dense that they block all light from their star, their orbits has to be strictly regulated. Since they have efficient interplanetary travel, they have weapons of mass destruction too. (Only nukes or worse have the necessary energy density.) This means, that if some of them engage in a local war, there is a high chance that they get shattered or change orbit. **The pieces would impact other habitats, breaking the well-orchestered dance of million orbits, and potentially leading to a system-wide cascade of collision, orbital perturbation and death.** Therefore a cutting-edge law enforcement is needed, which is able to calculate stationkeeping instructions for all habitats and enforce them very quickly if necessary, even by towing or occupying disobeying habitats. It looks like, that in the main Dyson volume only well organized and firmly held habitats will be allowed. Fringe groups or anarchists could have habitats on orbits significantly lower and higher than 1AU, where the temperature is not so comfortable, but they don't pose danger. Earth has about 200 countries. No effective congress, council or parlament could be formed from the representatives of millions of sovereign entities. This is extremely impractical. My suggestion is, that the swarm maintains a computer controlled orbital enforcement force. Everybody is free in his internal affairs, as long as they pay for the robo-cops and obey orders. The computers are designed to be neutral and fail-safe. But who knows, maybe they take over and forge an empire. Who don't feels comfortable in the system, can migrate to boiling Venus or freezing Mars distance. [Answer] Your thinking about a swarm (and anarchy) wrong. You can afford to let large numbers of people die but it is your duty to kill threats to the system even at the cost of your own life. Kill a billion here a billion there and you'll never get to meaningful damage in swarm worthy of Dyson. Distribute the ability to render habs inhospitable for a while. Ideally a system that kills a small number of habs at a time and either isn't scalable or can't be reused very often. Call it an asymmetric assured destruction system, where every hab can kill maybe dozens of others but is certain to get killed if they use it poorly, or is likely to kill themselves in the attempt. Say like dropping shortish halflife radioactive dust in their path. Or setting off a big nuke. You kill everyone on dozens of habs but if the bad guys are really that bad that's a fine trade off for saving the swarm. And if the bad guys aren't worth dying to stop who cares? The rogue hab attacks a neighbor, and the nearby ones say "that's not nice"; the rogue kills a few and gets killed either by surviving neighbors or by a deadman. Problem solved. A rogue empire has its outer edge killed. Now it can't easily expand, and you have a while to think about solutions. System government then lacks any teeth and works pretty much like the UN or the RFC system. [Answer] I don't know if political authority will flow up from the bottom or down from the top, or both, but the orbital habs should be organized in groups, and bigger groups, and even bigger groups and so on. For example, 10 habs may make a first level unit, 100 habs may make a second level unit, 1,000 habs may make a third level unit, 10,000 haps may make a fourth level unit, and so on up to 100,000,000 habs making an 8th level unit, 1,000,000,000 habs making a ninth level unit, 10,000,000,000 habs making a tenth level unit, etc. etc. for as many levels as needed. This table lists the levels of administrative divisions within each country: <https://en.wikipedia.org/wiki/List_of_administrative_divisions_by_country>[1](https://en.wikipedia.org/wiki/List_of_administrative_divisions_by_country) In the USA there are three levels below the national level: state, county, and municipal. The table has four columns for levels below the national level and in some countries the fourth column includes two levels. Thus in present day practice there are up to five levels of administrative divisions beneath the national level. Note that in the late Roman Empire there were also five levels of administrative division below the imperial level. A *pagus* was a subdivision of a *civitas* which was a city state with a republican form of self government formed out of a preexisting tribe or city, a group of *civitates* was supervised by a governor of a province, the governors of provinces were under the authority of vicars governing civil dioceses, who were subordinate to the four Praetorian prefects governing prefectures under the Emperor. Note that in *Star Wars* The Galactic Republic ruled more planets than there were *civitates* in the later Roman Empire but had fewer levels of administration. > > The most common organization for these new territories was to group regions into Sectors of about 50 inhabited worlds. Each sector is represented by a Senatorial Delegation. When the number of sectors became too large, sectors were organized into roughly a thousand regions, each represented by one delegation to the Senate. > > > <https://en.wikipedia.org/wiki/Galactic_Republic>[2](https://en.wikipedia.org/wiki/Galactic_Republic) So with about 50,000 planets in the Galactic Republic there are supposed to be only two levels of administration between the senate and an individual planet. And each senate delegation represented a region with a thousand planets. I have my doubts how well that would work. I don't know how administration may work with seven, eight, nine, ten, or more levels of administration. Theoretically a wide hierarchy could reduce the numbers of levels needed by having a a large number of subordinate units under each unit. For example, 100 habs in a first level unit, 10,000 habs in a second level unit, 1,000,000 habs in a third level unit, 100,000,000 habs in a fourth level unit, and 10,000,000,000 habs in a fifth level unit if needed. This would reduce the number of levels that orders and information are passed though, but it would make each level's task of supervising many units difficult. Or in a narrow hierarchy, units at each level would supervise a small number of units on the next level down. That would be an easier task. But then a larger number of levels of administration would be needed, possibly more levels than have ever been made to work in human history. In a government with many levels of administration, it is considered necessary to pass orders from the top down through many parallel hierarchies to be certain that the orders will reach the bottom and not be lost in transition. In a Dyson swarm one of the hierarchies could be the Habitat Inspection Service that inspects the structural integrity of the habitats to make sure they aren't about to fall apart and perhaps damage other habitats. Another hierarchy could be the Swarm Navigation Service that makes certain that all space ships travel on trajectories that won't strike any habitats if they fail to make course corrections. There could be a Swarm Space Navy or Swarm Space Guard to protect against invasions from outer space, defeat rebellions, and vaporise any spaceship with a trajectory calculated to impact on a habitat. Note that if a one "star" admiral commands the naval forces in ten habitats, for example, the highest ranking admirals might be at least seven "star" admirals, unlike in modern navies. There could be a Swarm Security Service to investigate any possible plots to revolt or commit terrorism. And maybe a Swarm Intelligence Service to investigate any possible plots to revolt or commit terrorism. And the Swarm Security Service and Swarm Intelligence Service would also investigate each other to make sure they are doing their jobs properly. And the Swarm Space Navy or Swarm Space Guard might have an intelligence service that investigated crimes, rebellion, terrorism, and the other spy agencies. Clearly the government of a Dyson swarm could have a complexity similar to that of a science fiction galactic empire. And if you write about a Dyson swarm or space empire with a monarchy, remember that unlike the usual idea in western civilization, a king is not the next step below an emperor. If the space realm has kings above dukes, it is likely to have kings of kings - or second level kings - above kings, kings of kings of kings - or third level kings - above kings of kings, and so on up to the empeor who might be equal to a tenth level king, for example. If the Emperor claims to be the rightful ruler of the universe, he might use hundredth level king or king to the thousandth power as one of his minor titles, even if his realm has far fewer than a hundred or a thousand levels of administration. [Answer] Before anything else, I'd look to history. Throughout the course of human events, we've always been explorers, pushing new boundaries and new frontiers, one of the best examples being the Europeans' discovery and colonization (or confiscation) of the Americas. These Europeans obviously were beholden to their mother countries and governments back home, who often were beholden to other countires and other governments with similar interests in the New World. Britain, Spain, and Portugal, for example, had a series of complex treaties and agreements about who owned what in America, often as influenced by mutually common authorities like the Catholic Church. However, as we know, control of the Americas did not exactly follow all these agreements. America was eventually dominated by the British, who were later overthrown by the colonies, who later still became the United States of America. In other words, there were plenty of bargains, treaties, and agreements between various people groups, but in the end, human self-interest, paired with the unmanageably vast distance of the Atlantic Ocean separating the New and Old Worlds, brought an end to most of those treaties. If mankind were to colonize space in any way, I imagine we'd face similar situations. The distances involved would be so vast, we'd try very hard to establish some kind of common system in the interest of political and economic balance, but in the end, this new and unfamiliar frontier would be conquered by those with the greatest will and the sharpest wit. I know this may seem nebulous, but the defining characteristics of such situations throughout history seem to be simple: mankind will always strive to find governance and commonality, but in the end, it's very difficult to maintain strong "long-distance relationships" between different people groups, particularly when colonizing a new frontier. If you're looking to imitate actual historical treaties (which is actually the best kind of plagiarism), I'd research those established in the colonization of the New World between various European powers. [Answer] I would think a federalist system would be a good way forward here. Yeah, I know I am biased and from the US, but this system has some good points. Here is a loose primer on how this could work without getting too out of control. I get that it's not exactly the same now as it was 200 years ago, but this is about the original intent. The US Constitution was a built from a series of compromises based around a few centralized premises and it came about after a more anarchic system existed between the end of the war of independence and the adoption of the US Constitution. The Idea is to give a central governing body enough authority to make general, over-arcing decisions for the good of the entire country while leaving the smaller units, the individual states, enough autonomy to take care of all the localized stuff. The result is that California, in a regulatory sense, is very different than Texas. Both are radically different from New York. The key line in the constitution that allows this is "Any Power not specifically granted to the Federal government is reserved to the States or the people" (I probably butchered the verbiage there, but that's what it means). The entire concept, then, is that the government has boundaries it cannot cross. This allows a lot of autonomy in each state. How it works in your system: Centralized government entity has specific powers to provide for infrastructure, common defense, and to regulate trade between individual habs. Basic ground rules that everyone has to abide by. These need to be carefully outlined and everyone needs to agree to them. After that, everything else is left to the individual habs themselves. That way you can have a Hab filled with people who behave one way and another with folks of a different philosophy. People could be able to move from one to another without government interference, and a common currency means trade is on a relatively even footing. Representatives for each hab function in roles for the overall government, making decisions for the system as a whole. No hab should be without a representative. Keep in mind that in the earliest days of the US, travel times for news was measured in weeks or months, so in a dyson swarm, information moving in terms of light minutes means that this system is still practical. It's not a perfect system, but it addresses a lot in terms of a balance between an overly strong central government and anarchy ]
[Question] [ TL:DR You and 1000-2000 unprepared and untrained settlers are stranded in an uninhabited area that has never had any human development. If you had nothing but the knowledge of how things work and are created, a *very few* makeshift tools, roughly what industrial level of technology would be able to be created in 5-10 years. Barring any natural disasters and working on the premise that everything goes according to plan. I'm not looking for an exact answer of say 1825 AD industrial level, as a lot of our technological development was hindered by societal restrictions. I'm after a rough ballpark idea of say 'pre-roman bronze age', early iron age, middle-ages, renaissance, industrial revolution industrial levels etc. etc. --- In the far-future, a bunch of ill-prepared tourists and refugees have crash landed on a liveable planet in an 'emergency craft' that has emergency rations, medical supplies, etc. They have enough to survive ~ 6 months to a year. They were not prepared for becoming 'settlers' and have no extensive preparation for the situation at hand. They have sent up a beacon sending SOS signals. They have no way of knowing if it's being heard and answered or not. They are waiting for rescue. All they have to do in the meantime is survive...it could take many years, if at all. Resources at hand: * The ships have a few high tech machines for specific tasks such as replicating ration food, medical equipment (maybe an xray or high tech portable MRI...I haven't figured out exactly what but compact and highly specialised is the key here), some surveying equipment. It has a very small seed reserve (for situations just like this), no *large* farming tools, no tools to make other tools. Maybe a *handful* of smaller farming tools, or at least items that could be fashioned into small farming tools like knifes, hatchets, scythes and hoes etc. These small tools, will wear out and need replacing fairly quickly. * In the group of 1000-2000 people, you have some scientists, some engineers and master-craftsman, some outdoors types and some farmers, some skilled manual labourers, mostly other trades (tourism, hospitality and administration etc), and people who have no real skills at all. They will have some guidance from people who sort of know what they are doing on how to survive, at least at first. They have lots of people with no specific 'useful' skillsets so they have plenty of manpower. * The Settlers also have an extensive computer databank providing knowledge on how to create tools, as well as how to create the tools to create the tools they will need from scratch, as well as farming best practises and how to grow crops etc. Technological knowledge loss is not an issue in this particular scenario. * The ships are not designed for extended use, and cannot power itself for any length of time, especially if damaged during re-entry or during later scavenging. High tech toys include a few rifles, some sort of perimeter warning device, and one or two types of heating sources. These heating gadgets could possible reach the necessary level for use in a forge. Nearly all high tech toys will be reduced to useless paperweights in a matter of weeks with no recharging. There is the possibility of several advanced solar panels to supply enough energy to power the database and some of the medical tech. They won't have the tech to be able to recreate more solar panels to increase power anytime soon. * The local alien wildlife has never seen humans and some are relatively tame but not domesticated. They will allow the approach of humans, and some may even allow humans to touch them, but being yoked to a wagon or plough is not yet feasible. With a focussed breeding program, it could take anywhere from 10-20 generations to domesticate the local wildlife. Depending on the growth and maturity rates of the wildlife this could be anywhere from 10-60 years. The 'Settlers' are going to be reliant on manpower in the short-term. * Humans are ingenious when it comes to survival situations and will be able to scavenge and transform items from one intended use to another, especially with several dozen scientists and engineers around. A few items, they won't be able to, or won't want to scavenge such as the medical tech and computer database. They will be able to scavenge some hard wearing metals and materials from the ships damaged hull, but not a lot. Just enough to get them started. So, the 'Settlers' initially have 'no' specialised tools, and no animal power. They have manpower, some skilled people who can learn new specialised crafts and they have access to knowledge on how to farm and how to create tools. They combine all their resources and energy into surviving for the long-term worst case scenario...no rescue. **Working from scratch, what sort of 'stable' technological industrial level could they expect to reach in the short-term?** let's say 5-10 years when the first animals start to become domesticated. Resources they will need: * Besides air, water and safety from unknown predators. * They will need to be able to find metal ores, extract the metal, shape the metal, create tools to create the tools. * They will need to use their created tools for farming. Let's assume familiar Earth like farming conditions (for the sake of the question). * They will need to find the alien equivalent of grass cereals and start the seed cultivation and domestication process (but this is not vital, as we harvested wild cereals for thousands of years). They also have a small seed reserve if nothing is found. * They need to figure out of the alien wildlife is consumable and start hunting meat. Shouldn't be too hard at first as the animals have no fear of humans. Yes, Hunting accidents will ensue. **Note**: We can't really use real colonial history, as most, if not all, colonies had 'all' necessary supplies pre-provided and 'regular' resupply for a lot of supplies/industrial equipment that the colony could not yet reproduce 'on-site'. I'm trying to figure out what level of industry to drop my far-future people to. I know the technology level that can be recreated will drop dramatically as the industrial infrastructure will need to be created from scratch. And I'm not really focussing on how far it will drop from, [what personal expertise will be needed](https://worldbuilding.stackexchange.com/questions/10648/what-technical-expertise-would-be-required-to-create-a-sustainable-colony) or [what resources will be needed](https://worldbuilding.stackexchange.com/questions/17436/what-are-the-most-important-raw-resources-for-a-human-colony) or [even how many of my settlers will be involved in production](https://worldbuilding.stackexchange.com/questions/18106/what-average-percentage-of-settlers-is-required-to-ensure-the-supply-of-food) or even [what are the minimum requirements for an off-world colony](https://worldbuilding.stackexchange.com/questions/8480/what-are-the-minimum-local-environment-requirements-for-a-human-colony) as this last one didn't focus on tool manufacturing or technology/industry level. What I'm focussing on is how far they could crawl back up the industrial ladder provided they had access to all technological theories and data. I need to figure out my starting point before I let them advance or fall further due to unforeseen alien encounters!! Would they immediately recover and reach an industrial level, or is more likely they end up in a Middle-ages or even earlier industrial period? EDIT: clarified I'm after the industrial level not the theoretical technology level that they may know. So they may know how to make an atom bomb or a space craft engine but what sort of physical industrial level would they be able to recreate with no pre-existing infrastructure and just the theoretical technology knowledge to help them. [Answer] Their knowledge base wouldn't change since you've got a nice computer system telling them what they need and a group of experts to be able to interpert that information and move it to the real world. After 10-15 they would probably end up with a bronze age industrial base, maybe iron if they found an easily accessible iron vein. The big killer here is the lack of domesticated wildlife. Without beasts of burden everything slows down, moving materials or providing power to machines is limited to human muscle power which means that everything that's done will have to be done small scale. Also domesticated animals will provide a regular food source which will improve farming efficiency which is nothing to sniff at given that you need a large group of farmers for every craftsman. Another limiter here is the need to build up experience, unless you're people have actually done the various tasks needed (hand plowing, copper/bronze casting) they still need to build up the experience to be able to do the tasks. It's all very well being told what you need to do, it's another thing to actually do it. Giving them some machines to fill in for this won't help as without the industrial base to repair them they will be prone to breaking down, usually at the worst possible moment. The good news is that once they have beasts of burden things will start to snowball. They can move around much more materials which means they can start to snowball up to the point of steam engines and once you're there things become a whole lot easier. A good resource for this is project rho (<http://www.projectrho.com/public_html/rocket/stellarcolony.php>) They've done an awful lot of work gaming out interstellar colonization. [Answer] ## They wouldn't change technology levels. Their technological level won't suddenly "drop down" as you believe it will. No, simply they'll be living in the rural version of where ever they were living before in this far-future. A lack of adequate tools doesn't suddenly mean you forget how to make them, especially since your group of "untrained" settlers includes scientists and engineers. --- The evolution of technology was not an evolution of actual machinery, but rather an evolution in ideas or in other words the development was the knowledge of how to make said machinery. People often find it striking that we were able to completely change the world in the few centuries after the industrial revolution compared to the relatively slight changes we were able to apply in the thousands of years prior. This becomes less strange however when you realize that implementing the technology itself is actually pretty easy. Coming up with the idea for that technology however, from scratch, is what was incredibly hard. [Answer] **Let's assume they get really really lucky** and have surface iron, copper, tin, flint, clay, coal and woodland all within a day or so walk of their landing zone. They also have some physically competent people, and a reasonable knowledge base available to them to be able to recognise what they've found. The key to their survival and rapid return of technological levels is that they don't need to invent the technologies related to their luxurious lifestyle, they just need the resources and craftsmanship. You're going to have to start at the stone age, crude flint tools. Axes and farming tools initially to start clearing clearing ground, cutting wood, growing any suitable crops and building shelter. This is going to take you some time to set up and is preliminary work before you move on a stage. You can use flint tool to mine copper and tin. Wood allows them to make charcoal, the first fuel that permits true smelting of metals. Between that, your copper and tin supplies, and some clay molds you're pushing into the bronze age in a matter of weeks. The great thing about bronze is that it doesn't have the complexities of iron, you can just cast it and it's as good as it gets. Clay allows them to make bricks. You're now looking at upgrading some of the buildings, building ovens (for cooking and making bricks) and building proper smelting facilities because the next thing you're going to do is start mining iron and coal. Good bronze tools were better than early iron tools, so don't worry too much about your bronze tools not being up to scratch. You'll need a blacksmith on hand to sharpen tools day to day anyway. Your first iron that doesn't go into making a new anvil or the blacksmith's own tools is going to be the core for your first copper wound generator (assuming you've found some magnetic rock). This is either wind or water powered, it doesn't really matter, but it's your first step into a technological age. All this can be done in months, depending on climate. Perhaps a year or two at most. Simply because nothing needs to be "invented", it's all existing knowledge that needs to be applied. It's all going to be done on a craftsman basis, you only need full industrialisation when you have the population to support it. **Of course if they don't get so lucky** then they could be spending months or years in the stone age, just hunting the resources to be able to take the next step. During the bronze age, copper and tin could be sourced from thousands of miles apart to support the industry. Your population can't support that and might have to work towards skipping bronze age and going directly into iron age. [Answer] Most chemical and physical processes we know of can be achieved in a variety of ways, which is fortunate because your resources (in terms of minerals) will be minimal. Scaling up basic smelting and chemical refinery is pretty much a guaranteed capability within a few months to 19th century levels. isoprene, urine, dead ants, sand and sediments..all that jazz. ofc it's high school desk scale a lot of the time, but if you only need a thin tube of waterproof rubber or some low quality copper wire..or some opaque glass right now.. that's all you need. Primary methods of gathering chemical resources are the same of course: animal, plant & mineral. Which brings up err 'is this planet mysterious?' Because one would expect that a life sustaining world would attract a great deal of attention and it's unlikely a random bunch of civilians is just 'flying' through un-surveyed territory..and if it's surveyed they'll have an excellent idea of where to find what minerals, there'll already be a database on the most profligate lifeforms at least. Now, I thought I saw a reference to surveying tools, but I can't find it now. 1: Expectations & Ambitions 2: Work Ethic & Social Stability 3: Survey accuracy/survey tools/luck Feeding 2000 people is easy, the colonists will want to strip back an area of terrain for crops, settle on high ground (in a valley) with a nearby 'fresh' water flow that doesn't show signs of 'seasonal' dry periods or massive flooding, access to aquifer. Animals and native plant-life wouldn't be so much a source of food as of chemicals, 'biofuels' are manifold and they'll be able to start producing electricity (negligible supply) if they wanted even before cutting down their first tree. They can reach 21st century technological production within 10 years if that's what they aim for, chemistry is chemistry, physics is physics, biology is biology, it's only a matter of having the raw materials within reach and the scale. Most industrial operations on earth suffer from having to do it better than anyone else(or have a captive audience) and a whole lot of social and socio-economic noise that can destroy perfectly good projects. All your guys have to do is get a job done. The first things they'll want to do is probably start clearing land, digging wells, making water purification systems and assembling shelter. Done such a way that they have worthwhile collateral effects (field stone, timber and plantfiber collection, defensive/irrigation ditch etc) If they weren't planning on crash landing, it's likely their first big worry that takes more than two minutes to solve will be clothing replacements, aside from anything else, physical labor and tourist/shipsuits probably don't mix well. I suggest becoming stranded in spring. Trying to detail too much. They'll be able to produce their own internal combustion engine within half a year(or just stick with steam if they wanted for a bit longer to prioritize other stuff), have brick houses before that, but manually mining isn't much fun so they'll probably go for explosives asap. one or two or all 3 can be used as energy sources for machinery and generate electricity, or that river. anyway, then it's a matter of mining mining mining until you have enough of various minerals to produce intermediate steps, catalysing agents, distilling processes, without planning out step by step i'd probably go with living like bronze age plebs with electricity whilst everything else goes to the 'progressive' effort of minimal scale processes to reach those intermediates until basic gathering processes can be automated. bear in mind that almost all products used in everyday life now and for many years is far more complex and involved than it really need be, and generally of a larger scale too. also, a stick can work as a scythe, you don't need to go to the effort of using your precious metal ores to make individual blades when you could save it up and make a mechanical (though perhaps initially human motivated) reaper. ]
[Question] [ So I'm writing a story that takes place in Saturn's atmosphere, and I've run into a bit of a problem. You see, I wanted it to be possible to have some pretty badass scenes with sci-fi fighter jets taking place. (Yes, I know that real life fighter plane combat is a lot of hoping the targeting computer is right about how to hit that speck miles away, if the speck is visible at all. I've got plot devices to fix that.) The problem is that planes need oxygen to run, and rockets are too inefficient for long distance travel. Unless you do suborbital jumps, I guess, but I want planes dammit. **My question is, what sort of propulsion system could work in the atmosphere of Saturn?** I know electrically driven propellers might do the job, but that feels kind of slow. Note: Planes need not be SSTO capable, they can land and refuel at large stations in the atmosphere at "surface" level (1 atm pressure) [Answer] You do not actually need combustion for a jet engine. The integrated turbine is a heat engine: its energy comes from increasing the thermal energy by fuel combustion. But any method of increasing the energy between the compressor and turbine works. A heat exchanger from nuclear power plant or even an electric heater will work without really changing anything fundamental. The only real issue is that burning fuel within the the engine is very efficient method of transferring the heat into the medium. So if fuel combustion is an option that is probably what will be used. Not sure if anything other than those nuclear jet prototypes has even been ever built. Unless you need those days of flight time or operational range that exceeds the Earth circumference burning fuel has always been just better. There are actually other options such as simply supplying oxidizers (or some other form of two component fuel) or rotating the fans and the entire compression side with electric engines without having the integrated turbine.The turbine is not actually needed for jet engine. It is simply the most efficient method of powering the engine per mass we have, so it is the only one we really use. (Aircraft being very sensitive to excess mass.) My guess would be that is you need extreme range you use nuclear engines with electric engines powered by whatnot used for short range. This because most current or projected nuclear power plants have fairly large minimum mass. Although this is largely shielding. The proposed supersonic nuclear missile that was specifically designed to contaminate whatever it flies over was fairly efficient. It really all comes down what kinds of power tech your people have available. [Answer] The fighter aircraft could be a wingless electromagnetic air vehicle (WEAV) which gets its lift and propulsion by ionizing the surrounding air and gaining lift. Details [here](https://www.scientificamerican.com/article/worlds-first-flying-saucer/) for this type of vehicle which resembles a flying saucer. The source is the *Scientific American*. > > The saucer will hover and propel itself using electrodes that cover its surface to ionize the surrounding air into plasma. Gases > (such as air, which has an equal number of positive and negative > charges) become plasma when energy (such as heat or electricity) > causes some of the gas's atoms to lose their negatively charged > electrons, creating atoms with a positive charge, or positive ions, > surrounded by the newly detached electrons. Using an onboard source of > energy (such as a battery, ultracapacitor, solar panel or any > combination thereof), the electrodes will send an electrical current > into the plasma, causing the plasma to push against the neutral > (noncharged) air surrounding the craft, theoretically generating > enough force for liftoff and movement in different directions > (depending on where on the craft's surface you direct the electrical > current). > > > The fighters can solve their energy problems by using an matter-antimatter power system. Assuming that the practical problems of using antimatter as a power source have been solved. A similar magnetohydrodynamic (MHD) vehicle was described in an article "How To Design A Flying Saucer" by Dr Richard J Rosa published in *Analog* and reprinted in *The Analog Science Fact Reader* (1974) edited by Ben Bova. That suggested that this type of craft could produce large volumes of low-speed ionized air for travelling slowly and hovering, but narrow its air intake to generate smaller volumes of high-speed ionized air to accelerate to high velocities. Rosa's proposed MHD vehicle could land and take-off VTOL style, so it wouldn't need extensive infrastructure. The fighters could accelerate through the Saturnian atmosphere and once it reached the upper atmosphere use an matter-antimatter power system to ionize reaction mass such as water stored in propellant tanks to attain orbital velocities to rendezvous with the space-station bases or spaceships orbiting the planet Saturn. Whichever type of fuel is for reaction mass, the procedure is the same. using the power output from its matter-antimatter system the reaction mass is totally ionized and accelerated via powerful magnetohydrodynamic accelerators. Instead of an exhaust velocity of 4 km/s from chemical rocket propulsion MHD accelerated ionized reaction mass could have an exhaust of 100 km/s. This means the vehicle will consume far less reaction mass than a chemical rocket system. [Answer] The simplest way to build a jet engine (or any other combustion engine) designed for Saturn's mostly hydrogen atmosphere (~75% H2, 25% He, with some trace gasses) is simply to use oxygen as its fuel. Wouldn't surprise me if all you had to do was change the fuel flow metering on a standard jet engine, and install insulated liquid oxygen tanks. PS: Which brings up another question that my knowledge of chemistry is insufficient to answer. We use hydrocarbons for fuel in our oxygen-rich atmosphere because (in part) they're conveniently liquid at ambient temperature. Are there equivalent oxygen-rich liquids that we could burn in a hydrogen atmosphere? [Answer] While a realistic scenario would be the WEAV designs referenced by a4android, the OP is clearly hoping for some sort of aerodynamic vehicles. The problem is actually multifold. The atmosphere has no free oxygen to allow the use of conventional jet engines, the distances to cover are orders of magnitude longer than that of Earth (imagine flying from an air base in Minnesota to a spot over the Indian Ocean before you even encounter the first enemy craft, then having to dogfight, then flying back. Without air to air refuelling your "fighter" would be the size of an A-380 [![enter image description here](https://i.stack.imgur.com/hDh3N.jpg)](https://i.stack.imgur.com/hDh3N.jpg) *A-380 in flight* Finally, the atmosphere of Saturn itself is very violent, with some of the fastest winds recorded in the Solar System. Planes caught in a downdraft might have a real possibility of being sucked into a layer of the atmosphere where the pressure exceeds the aircraft's "crush depth", so instead of air war we are looking at a weird hybrid of air and submarine warfare..... However, there may be some ways to handwave this. If you can get to Saturn in the first place, there is probably some compact energy source like fusion, so a suitably large airframe coupled to a suitably small fusion reactor would make a sort of rocket or ramjet powered craft (the fusion reactor can be heating atmospheric gases, for example). This is similar to the proposed nuclear powered aircraft designs of the 1950's. [![enter image description here](https://i.stack.imgur.com/TXKMe.gif)](https://i.stack.imgur.com/TXKMe.gif) *Nuclear jet engine* I would expect the aircraft to be at least the size of an F-15 "Strike Eagle" to house the fusion plant and any associated equipment. Because you are working in a very complex fluid dynamic environment, the airframe would need to be able to "morph" appropriately. If you are in the lower, denser layers of the atmosphere, you need less lifting surface, while in the upper layers, you will need far more lifting surfaces. As well, you will need a strong shape to resist "crush depths" should you be forced down for whatever reason. A large "blended wing" lifting body design is probably a good starting point: [![enter image description here](https://i.stack.imgur.com/bUtHW.jpg)](https://i.stack.imgur.com/bUtHW.jpg) *Boeing X-48 Blended wing design* Because of the added complications of atmospheric pressure and turbulence, regular weapons like air to air missiles or SFnal weapons like lasers would have limited utility (they would not have sufficient range, for example). This might be worked around by arming the craft with a powerful rail or coilgun. The projectile could have limited ability to be guided onto target, but as the range increases the effects of atmospheric drag and turbulence would eventually break the target lock and the round would fall into the depths of Saturn. Explosive warheads would not really be necessary. One issue which you have not brought up is where these craft are going to be based, or why they need to fly and fight in the atmosphere anyway? The design I hand waved *could* serve as an SSTO and fly to and from space to carriers orbiting Saturn, but the "why" is pretty open. ]
[Question] [ I'm trying do design a feasible passenger/cargo spacecraft stationed on a [space station](https://worldbuilding.stackexchange.com/questions/49106/is-my-space-station-feasible "Is my space station feasible"). It's a far future setting, but I'd like to stay as close to real physics as possible, specifically, anti-gravity is *not* available. At the same time there are means to provide large amounts of energy. It doesn't matter how it's achieved. Some kind of a nuclear reactor or even something like a matter/antimatter reaction assembly would be ok. **The spacecraft should have following capabilities:** * efficient and safe landing on a terrestrial planet or a moon without any pre-existing infrastructure; * atmospheric flight; * orbital launch without any pre-existing infrastructure; * able to carry at least 5 passengers and $\leq$ 50 metric tons / $\leq$ 200 $m^3$ of cargo to and from the surface; * landing and orbital launch with g-forces safe for regular untrained people; * reusable. **Other requirements:** * single-staged system; * maximum dimensions: width: 90m, length: 90m, height: 50m. Is that possible? Are there any problems with the concept I'm missing? What kind of propulsion system would be viable for this spacecraft? [Answer] Since you have rid yourself of [The Tyranny of The Rocket Equation](http://www.nasa.gov/mission_pages/station/expeditions/expedition30/tryanny.html) by solving the problem of fuel, you can make this in any way you want. Several emerging technologies, or technologies that have failed due to some limitations that we cannot get past yet, may serve you here. Things such as the [aerospike engine](https://en.wikipedia.org/wiki/Aerospike_engine) (currently fails due to cooling / material requirements) might be useful for your design. I would argue for a [spaceplane](https://en.wikipedia.org/wiki/Spaceplane) that takes off conventionally to a high altitude, retracts its wings and goes hypersonic in excess of Mach 15, then "leaps" out of the atmosphere and gives itself a nice little [orbital insertion](https://en.wikipedia.org/wiki/Orbit_insertion) boost. [Answer] The spacecraft might be a wingless electromagnetic air vehicle (WEAV) which gets its lift by ionizing the surrounding air and gaining lift. Details [here](http://www.scientificamerican.com/article/worlds-first-flying-saucer/) and it's not everyday the citation is to the *Scientific American* about a flying saucer. > > The saucer will hover and propel itself using electrodes that cover its surface to ionize the surrounding air into plasma. Gases (such as air, which has an equal number of positive and negative charges) become plasma when energy (such as heat or electricity) causes some of the gas's atoms to lose their negatively charged electrons, creating atoms with a positive charge, or positive ions, surrounded by the newly detached electrons. Using an onboard source of energy (such as a battery, ultracapacitor, solar panel or any combination thereof), the electrodes will send an electrical current into the plasma, causing the plasma to push against the neutral (noncharged) air surrounding the craft, theoretically generating enough force for liftoff and movement in different directions (depending on where on the craft's surface you direct the electrical current). > > > Fortunately the single-stage spacecraft is a far-future vehicle with possible matter-antimatter power system because that solves this problem with WEAV. Therefore, it is reasonable to assume that the practical problems of using antimatter as a power source have been solved. This vehicle is operating in the far-future after all. > > The biggest hurdle to building a WEAV large enough to carry passengers would be making the craft light, yet powerful enough to lift its cargo and energy source. > > > A similar magnetohydrodynamic (MHD) vehicle was described in an article "How To Design A Flying Saucer" by Dr Richard J Rosa published in *Analog* and reprinted in *The Analog Science Fact Reader* (1974) edited by Ben Bova. That suggested that this type of craft could produce large volumes of low-speed ionized air for travelling slowly and hovering, but narrow its air intake to generate smaller volumes of high-speed ionized air to accelerate to high velocities. Rosa's proposed MHD vehicle could land and take-off VTOL style, so it wouldn't need extensive infrastructure. A WEAV-type spacecraft could accelerate through the air and once it reached the upper atmosphere use its matter-antimatter power system to ionize reaction mass such as water stored in propellent tanks to attain orbital velocities to rendezvous with the space-station. **ADDED TO EDIT** A single-stage spacecraft with a matter-antimatter power source can effectively boost itself to whatever speed its operators desire. This will be more than sufficient to power itself during a WEAV flight mode. The WEAV flight modes will be for powered in the atmosphere during descent and ascent. Landings and take-offs will be VTOL. With a matter-antimatter power source this will generate considerably more energy than needed to attain orbital velocity. Using direct mass annihilation of matter and antimatter for propulsion would produce large amounts of gamma radiation. This is not good. However, it could easily be used to drive a powerful rocket propulsion system. There are two types of reaction mass the vehicle can use. One, as suggested above is water. Two, is liquid air. The liquid air could be produced while the spacecraft is landed. This assures the vehicle will be lighter during its planetary descent. Water might also be collected from the planet's surface. Otherwise it would have to be carried in the vehicle's fuel tanks. Whichever type of fuel is for reaction mass, the procedure is the same. using the power output from its matter-antimatter system the reaction mass is totally ionized and accelerated via powerful magnetohydrodynamic accelerators. Instead of an exhaust velocity of 4 km/s from chemical rocket propulsion MHD accelerated ionized reaction mass could have an exhaust of 100 km/s. This means the vehicle will consume far less reaction mass than a chemical rocket system. The vehicle will also be able to regulate its rate of acceleration, so even untrained personnel could fly this type of vehicle without too much discomfort or distress. This could be an acceleration that keeps itself to no more than two gravities during the rocket propulsion phase. However, with engines as powerful as these it would be easily possible to attain far greater rates of acceleration. But the for the sake of its personnel the acceleration can be kept within safe limits. The MHD rocket mode would be used for approaches to take-offs and landings from and on to a planet. Either decelerating from or accelerating up to orbital velocity, for travel either from or to the space-station the vehicle could use a plasma propulsion system with an acceleration of about one centimetre per second squared. This version of a single-stage spacecraft is designed to fully exploit the power capacity of matter-antimatter generator. It has three flight and propulsion modes: (1) WEAV plasma-lift technology for flight in atmospheres during ascent and descent. (2) A high-impulse fully ionized reaction mass rocket propulsion system enhanced by MHD accelerators with an exhaust velocity of around 100 km/s. (3) A plasma propulsion system for interplanetary travel at an acceleration of one centimetre per second squared. It also operates at levels of g-forces that are safe for regular untrained personnel. [Answer] First off, I imagine medium future space launches to go one of two ways: Either a massive structure that ferries things to space like a [space elevator](https://en.wikipedia.org/wiki/Space_elevator) or [skyhook](https://en.wikipedia.org/wiki/Skyhook_%28structure%29), or a ground based launch system that provides the energy needed for launch like a [mass driver](https://en.wikipedia.org/wiki/Mass_driver) or [beam launcher](https://en.wikipedia.org/wiki/Beam-powered_propulsion). These don't meet your specs, but the reason that I mention them is that if they become feasible, they will probably replace the development of any rocket-based systems because they are not subject to the tyranny of the rocket equation. So, if you want a universe where advanced rockets are the thing, it probably shouldn't have any of the aforementioned methods since they would out-compete said rockets. Now on to rockets. The best idea I have seen thus far is [SABRE](https://en.wikipedia.org/wiki/SABRE_%28rocket_engine%29) which is really only a marginal improvement over a newer chemical rocket. Also important, is that SABRE may not work if your atmosphere isn't about the same pressure as earth's, and will not work if your atmosphere has too little oxygen. So you can't say its useful for all terrestrial plants/moons. Nuclear rockets do not have what it takes. [NERVA](https://en.wikipedia.org/wiki/NERVA) was the closest to operational that such a rocket has ever been. It had a thrust to weight ratio of 1:5.2, so it couldn't make it to space. Nuclear reactors are heavy and I'm confident no fission system could ever have a thrust to weight above 1. For fusion rockets, the mechanics are anyone's guess at this point so too I can't say if you could use them to get to space. The various electromagnetic propulsion methods produce great specific impulse, but at the cost of low thrust and thrust:weight of less than one. So in conclusion, I'm just not aware of a proposed technology that gets you into space out of a earth-like gravity well much more efficiently than a chemical rocket. I feel that for realistic sci-fi, humanity will be divided between those who live in gravity wells, and those who don't, and there won't be too much intercourse between them. [Answer] **Propulsion Tech** Nuclear-Thermal rockets have already been mentioned, but let's tailor that more towards your question. You said there's no tech limit? Then let's go with a **Fusion**-Thermal rocket! Working principles are the same - instead of burning two reactants for thrust you pass liquefied-gas over something hot to make it turn into a gassy-gas. The difference is our heat source (and level of heat.) Using your star-core hot fusion reactor as a heat source makes things a lot more efficient - the higher temperature exhaust plasma means it's moving at a higher speed, and thus our Specific Impulse (Gas mileage for rockets) is far, far superior. It also opens up an interesting tradeoff. Since our reactor outputs a fixed amount of heat energy per second, if I run my engines in low thrust mode I can get absurdly high ISP. This is because I'm putting a huge amount of heat energy into a tiny amount of fuel. Great for orbital ops, but not so much for launch/landing. For that I'd dump more fuel into the rocket for worse efficiency but vastly increased thrust. As for fuel, you can just use air. If you're in a planetary atmosphere, just scoop up whatever's there and pass it over your engine - it'll work just as good in inert atmospheres as oxygenated ones. When you're in space, rely on an internal supply of liquid hydrogen. It's not a huge issue because you're probably going to need low-thrust high-efficiency maneuvers for orbital ops anyway. SCRAMJets are another option, but one that comes with some issues. They only work at already-high speeds in earths atmosphere, and they're very fault-intolerant. This has mostly to do with shaping the shockwaves to stay inside the engine - there's some speculative designs for variable-geometry SCRAMJets that remain viable over a wider range of airspeeds. Problem is, engines are heavy, and tend to work best only in specific areas. I could keep tacking on different types of engines, but that will add a huge mass-penalty. SCRAMJets have a slight advantage here because they require no moving parts, but they still have to be very robustly built to handle the forces and heat loads they're put under. **The craft itself** The fact that we're dealing with hyper-sonic flight and re-entry limits our options for shape a lot. Something like an X-33 Venture Star like lifting body would work well in those regimes (And you want to optimize it for those regimes, because if you don't it'll shred your SSTO and crew. The space-planes from Avatar are - regrettably - another good example, but not quite as good as the first, because those thin wings aren't too good for hyper-sonic flight. If the design can allow it, having tilting engines in the craft would work pretty well for your VTOL requirement. The mechanisms to do this add a lot of weight, complexity, fragility, and space requirements to the vehicle, though. What I'd do is mount my fusion reactor(s) so that they're in-line with the center of mass. This way I can vent the hydrogen plasma straight down for VTOL thrust, and then backwards for forward thrust. If you want the multi-engine option and you can come up with a way to make low-mass SCRAMJets, you can tuck a few of them into the craft. This also depends on how powerful your fusion drives are - too good and the energy release of burning hydrogen in your SCRAMJet is going to make them pathetic and worthless. This is all very speculative, but you did say no tech-limit. PS. Stay away from Antimatter. It sounds cool but the problems are almost too numerous to count. [Answer] To land on planets without infrastructure, the ship would have to take off and land like a helicopter since a runway would not be available. To fly at speed through the atmosphere, an aerodynamic 'plane' design would be needed. I imagine your ship would look something like a reaver from planetside2: [![Reaver](https://i.stack.imgur.com/x6x2H.png)](https://i.stack.imgur.com/x6x2H.png) The wings on this craft rotate, so that the jets can point either downwards to hover, or backwards for flight. The advantage of wings is the craft can glide on re-entering the atmosphere, removing the need for extra fuel until it comes to land. As michael Karnerfors said, a spaceplane is your best bet. The problem here is fuel: [![Space shuttle](https://i.stack.imgur.com/83j2o.jpg)](https://i.stack.imgur.com/83j2o.jpg) Using a realistic fuel, this craft would need a new set of rockets every time you wanted to go back into space. According to [wikipedia](https://en.wikipedia.org/wiki/Reusable_launch_system): > > No completely reusable orbital launch system is currently in use. The closest example was the partially reusable Space Shuttle. The orbiter, which included the Space Shuttle main engines, and the two solid rocket boosters, were reused after several months of refitting work for each launch. The external tank and launch vehicle load frame were discarded after each flight. However, several at least partially reusable systems are currently under development, such as the Falcon 9 full thrust (first stage). > > > The falcon 9 is the only other existing reusable system, however it cannot fly in the atmosphere (apart from going straight up and straight down). Your best bet is something like the reaver, but with a futuristic fuel which is both light and powerful, and can be obtained on most planets to refuel after landing. (maybe something radioactive, however this may damage the atmosphere significantly with radiation.) **EDIT:** Assuming, as the question states, a new fututistic fuel is readily available, the reaver design would work well. A futuristic fuel might produce enough energy to repeatedly enter and leave orbit without needing a refuel or using dispensible rockets. [Answer] The best general answer is that you will need to use some sort of external power source to provide the energy needed for flight operations. Laser thermal or microwave beaming of energy to heat and expel reaction mass such as water or liquid hydrogen is a near term possibility, but even with an ISP of 8-1200, you will still probably be strictly limited to how much cargo or passengers you can carry. You also have the issue of restocking your ship with reaction mass for every flight, and the laser infrastructure to provide the energy (not just the laser, but the tracking infrastructure, heat rejection devices and other ancillary equipment). a4android's answer provides an alternative, and Leik Myrabo worked on variations of this idea through the 1980's and 90's. Direct thrust by heating the air to a plasma or indirect thrust using MHD accelerators on the outer surface of the craft were all explored in various levels of detail, and a laser driven rocket was launched at a test range (the limit was preventing the laser from "blinding" satellites passing overhead). This [video](https://www.youtube.com/watch?v=-Nm16wp0kMs) gives you an idea of what was being done. So the short answer is that there are technologies which can bring you close to the goal you are seeking, but generally require external energy infrastructure for propulsion. Flight within an atmosphere is no problem, but flight in free space or to an airless moon/asteroid will still require the heating and expulsion of reaction mass, limiting you to vehicles with ISP's of between 8-1200. (For comparison, the best chemical reaction of H2 and O2 gives you an ISP of 425-450. The Space Shuttle carried about 2000 *tons* of propellant in the External Tank, and still needed two solid fuel boosters to assist it in lifting off). ]
[Question] [ The following question takes place in Medwedia, my fictional country populated by anthropomorphic bears. Medwedia is an ultraconservative totalitarian militaristic ultranationalist dictatorship that is disguised as an authoritarian one-party semi-democracy (mock elections and everything; however, those who cast the wrong votes disappear within 24 hours, etc...). Basically, anything that is beyond communal level is tightly controlled by the state. The technology is modern. However, some laws are archaic (flogging is a widespread punishment, those who steal an apple will have their hands amputated, etc...). To fit with the "conservative" part, I want to severely reduce social mobility, e.g. the ability to (usually) raise one's social status. However, I want to do that without imposing a legal aristocracy with too many privileges as this would exclude the bourgeoise and the economical upper class. The main reasoning for this would be pure traditionalism coupled with the belief that "those who know their place and don't litter their heads with the desire to become rich will work harder". The following measures have been enacted in various points in Medwedian history (Note: girls usually don't attend a Gymnasium or university and are instead prepared to become housewives, regardless of social class. Women can't vote or drive cars and must obey their husbands. Girls are usually kept at home or attend girls' schools.): * Education: + Attendance of a "Gymnasium", an academically oriented school, is required in order for a person to go to university (Look up the German Gymnasium). Good grades are of course a requirement; however, it is mandated that "Those who wish to send their children to the Gymnasium must show a certain level of financial credibility and be ready to sacrifice money for their son's education." Various fees must be paid prior to enrollment and important examinations; even the minimal monthly tuition fee as imposed by the state exceeds the yearly salary of a factory worker. + Same thing with universities. A price floor is enacted for universities that is not problematic for the majority of those who could send their children to a Gymnasium. However, the tuition fees for some of Medwedia's elite universities (an elite university degree makes one's life easier in many ways) are very high and the tax which has to be paid to send one's child to a foreign university makes even the rich shudder. Note: parents usually pay for their child's university education. + While a Gymnasium teaches one academic excellence, life skills and the topics covered are variable and interesting, the "Community School", "Elementary School" or "Professional School" (name varies by province), which is free or has low tuition fees affordable by everybody, limits the skills given to basic arithmetics required for monetary calculations, reading and writing and various manual skills (woodworking, etc...) which are replaced with sciences in the Gymnasium. Those who go to a "Professional School" are not able to go to university and are mandated to seek a low–qualification profession or an apprenticeship. + Some provinces require that parents who want to send their children to a Gymnasium must have attended such a school by themselves or even have an university degree. + Of course, the schools themselves may impose their own limits if they wish (and are encouraged to) such as "parents must have at least $1M to send their child here". + Many private or even state-owned boarding schools with very high tuition exist. Rich parents are encouraged to send their children here so that their children will grow up in a protected and closed society. Those schools prepare children for a life that includes many responsibilities but is luxurious: in some schools, children have servants, often poorer kids from a nearby village who attend a "Professional School" in the evening or on some weekdays only and have to support their family by working during the day. + Those who are sent to "Professional Schools" are told that they will contribute to society as manual workers just like doctors or politicians do and that one can be always proud to serve his country and fulfill his duty if he works excellently. They are told that a country where everybody is rich is damned to collapse. + On the other hand, those who are sent to a Gymnasium are told that they are privileged and will enjoy a luxurious life that will be coupled with higher responsibilities. They will be taught to feel a sense of material superiority. * Career and Taxation: + The tax rate is relatively flat with only slight variations based on a person's salary or economic status. It benefits the rich. In some provinces, those who did NOT go to university must pay an additional tax. + Men who continue the profession of their father if they do not go to university are rewarded. Women who become housewives are rewarded. + Men are drafted at the age of 18 for 2 years' worth of military service. Exempt are university students and some apprentices or those who can "buy themselves free". An university degree is required to become an officer. People who do not have an university degree but still choose to sign a lifelong contract to become soldiers or policemen are rewarded. In fact, over 5% of the Medwedian population (the total population is approximately 242 millions) consists of soldiers and policemen. * Government: + There is of course only a partial or fake democracy, which means that the opinion of the masses is rarely taken into account prior to governmental decisions. When it comes to a fake vote, all men older than 33 may vote. However, voting rights are based on taxation: citizens are separated into 10 "Taxation Classes" that correspond to the number of votes they have. + Those who wish to become politicians must have an university degree, a Gymnasium degree may be enough in communal politics. They also must show that they are "financially credible", e.g. poses a certain amount of money. Almost every member of the leadership caste has served or is serving in the military or in the police (which is a paramilitary organization and only differs from the military due to the fact that it is a subject of the Ministry of Internal Affairs, not the Ministry of Defence). * Economy: + Those who wish to found a company must show a degree of education, usually a Gymnasium or even an university degree. + Those who do not have a Gymnasium degree, if founding or inheriting a company or firm, must stick to "the profession of their father or a comparable profession". It should be for example no problem for the son of a farmer to inherit the farm. + A certain amount of money and an academic degree is required to own certain amounts of land or poses firms of certain size. Sometimes, farmers who accumulate too much land and wealth are partially evicted and the land is sold to a rich landowner to prevent the farmer from becoming one. What do you think of these measures? Can you suggest more measures that openly or not decrease social mobility? [Answer] You're working hard to prevent the rise of the poor here, but you've neglected to prevent the fall of the wealthy. The British aristocracy always had a percentage of impoverished nobility, who for whatever reason, still had titles but no longer had any money. The way they often dealt with this was to marry one of the children off to a family with money but no title. This meant that the children of the merchant inherited a title and the noble family once again had money. Allow a small amount of social mobility, let a merchant join the elite once in a while, so their children's inheritance can refresh the wealth of the existing ruling class. Let the occasional gentleman farmer get rich and marry his daughter off to the local lord. It keeps everyone on their toes and keeps the money where it belongs. [Answer] I'd say that the economic measures you've enforced are a bit too explicit in its attempt to suppress economic mobility. The downsides of such an explicit methodology are that it would be too culturally obvious to the working class to be stable. Instead of explicitly limiting workers by partial eviction and mandating education, I'd recommend a more implicit conservatism. For example, a flat tax rate (promoted as egalitarian, but otherwise stifling the working class) and the ownership of working equipment by the upper class would stifle economic mobility. Ultra-conservatism must have a core ideology that it promotes, instead of simply being diabolical, for it to be sustainable. Instead of mandating education for loans/land-ownership, have an interview process that relies heavily upon "moral character," which is heavily reliant upon the conditions of a citizens' upbringing. Form an ideology for the conservative state, and from there form policies that undermine the working class but also uphold certain core beliefs. [Answer] Instead of eviction based on amount of land, institute a high land tax. Make it less cost effective to own farm beyond a certain size unless you're also rich enough to buy sufficient machinery, or hire enough people. This keeps upstart hicks from threatening the rich. Same with firms, put in fees in specific places. Ensure that firms beyond a certain size meet additional requirements, while these are waived for larger corporations (e.g., tax breaks). Limit judicial access, add fees for legal processes to discourage frivolous litigation. Most importantly, 1. Limit access to credit, or at least increase the costs 2. Restrictive copyrights/patents to stifle innovation [Answer] I second what nzaman said. Limit access to credit, loans, mortgages, etc. Who can even buy a place without a mortgage, everyone would be leasing forever (except the wealthy) and not gain capital through property ownership. You can also impose a tax on assets in savings (as part of an economic stimulus push), making it impossible for someone to save up enough to buy property. The rich of course would own property and not face the asset tax since their money is not in savings. [Answer] The key to curbing social mobility and making it stable is to make it look like you're "helping" the poor. That way anyone who protests can immediately be branded a monster who just wants children to starve. Mandatory education is a good first step. Make sure the ruling classes control what's taught. Make sure what is taught always boils down to "Without the ruling class, you'd all be eating poison while working 120 hours a week in some rich man's honey factory." Then you start throwing more on top of it, all to "help the poor." Start with a minimum wage. Everyone thinks it will be awesome for the poor since they'll all get paid more. Especially where that's exactly what the schools teach everyone from a young age that it does. In reality it means that anyone who produces less than that amount per hour at a particular job will never be hired for that job. Set it high enough that menial labor jobs are almost never worth hiring someone to do. Now those few people who aren't successfully herded into the schools for indoctrination won't have the skills necessary to ever get any kind of job, and so won't be able to afford to pay for education and training without going to a government-run school where you can control what they're taught. Be sure to spin this into another reinforcement of how wonderful the ruling class is for providing education opportunities to people who would never, ever have been able to afford to pay for it themselves. If people catch on to the minimum wage not actually making things better, then go for mandatory paid vacation, sick leave, health insurance, and whatever other extras you can think of that will drive up the cost of hiring unskilled labour, but that the quasi-illiterate masses won't think of in terms of dollars and cents. This doesn't keep the poor from starting their own business and hiring out their labour that way though, so the next step is business licensing. Claim that this is to protect the general public from fraudsters so they'll accept it as necessary, and be sure to instill a pathological fear of unlicensed businesses in schoolchildren from a young age. ("If the health department didn't license and inspect restaurants, why they'd just charge you a high price for half-rotten roadkill and you'd die of food poisoning! Aren't you so lucky we're here to protect you?") Set the basic license costs and paperwork levels such that an aspiring businessperson can expect to spend more time on government busywork than on serving customers and pay more in license fees than they bring in in income for the first several years. This will dissuade the majority of lower-class people from attempting to get off the dole. Oh, by the way, have a strong welfare system. Advertise it as a way to make sure that nobody starves or goes hungry just because they don't have a job. Scale the benefits such that a person on the dole can live more comfortably than someone with a minimum-wage job, and make sure that any attempt to earn extra income results in a decrease of benefit that is larger than the extra income earned. Eventually this will result in the very poorest people not even bothering to look for extra work. Then use the threat of taking away their "benefits" to coerce them into voting the way the ruling class wants them to so as to maintain the illusion that the system is a democracy. Make sure to regulate every major sector of the economy as tightly as possible. Talk to the major players in each sector when you're setting this up and get their input about what the regulations should be. Ignore the small and medium players. The big players should be sufficiently intelligent to recommend regulatory measures that will have a high, fixed cost of compliance. They can afford to pay it and still make a profit, but make sure the small-timers are unable to and get forced out. That's how you know it's at the right level to prevent anyone who doesn't have the sponsorship of the ruling class from entering the field. Again, spin this as "protecting the consumer from corporate greed." Introduce a strongly progressive income tax code to "make the rich pay their fair share." Make sure you calibrate it to match the diminishing marginal value of money in your culture as closely as possible. (For the non-economists, DMVM refers to the fact that the more money you have, the less you value any individual unit of it. If someone is considering working extra hard to earn more money to try to improve their social class, you want to be taxing enough more of the new income away that they decide it's not worth it. Working twice as hard for twice as much people might be willing to do. Working twice as hard for only a 50% boost is much less appealing.) Be sure to offer tax breaks and exemptions to those who do what the ruling class wants. There's no better way to bribe someone than by simply letting them keep their own money. Make sure everyone is taught that giving tax breaks is necessary to boost the economy, but be certain to never give the lower and middle classes both a tax break and a regulation reduction at the same time. That would let them maybe actually do something interesting. If something interesting does slip through and start to take off, regulate it as soon as possible, preferably in a way that forces everyone but the ruling-class' favorites out of the business. Once you've got things going nicely, expand minimum wage laws so as to forbid volunteer labor except for government approved organizations or as part of a government approved school curriculum. Pitch this as "preventing greedy businesses from taking advantage of the young and inexperienced." In truth you're just cutting off the last possibility of people learning a trade without being thoroughly indoctrinated in one of the government schools. Make sure they never suspect this. Encourage self-destructive behaviours among the lower classes. Do not teach them how to write a budget. Do teach them how to apply for credit cards. Make sure that everyone thinks spending their entire life in debt is normal. Do your best to stigmatize saving, or even the very idea that saving up to buy something or start a business instead of going into debt is a viable way to do it. Institute heavy property taxes. Preferably let the people vote for them in order to fund certain projects, but make sure that the majority of the voters don't actually own any property. Calibrate the quantity of projects (and therefore the rate of taxation) so that farmers and businesses that need property to make their living cannot make enough profit to be able to expand (except very slowly.) Make sure anyone who complains about their high property taxes gets painted as a "rich person" who should be paying "their fair share". Or, even better, as uneducated hicks. Institute heavy estate taxes ("It's not fair that the children of rich people start their lives out rich! They should have to work for it just like everyone else!") Make payment due within 30 days of death. The goal is that whatever small businesses do manage to crop up among the lower class should have to sell at a substantial loss in order to pay the tax bill on time rather than being transferred to the next generation. If the children of a successful entrepreneur inherit anything other than personal trinkets of sentimental value you're doing it wrong. Make sure there are ways around this for people rich enough to hire expensive tax accountants. (Obviously tax accountants should be heavily regulated so you can weed out the ones who try to help "the wrong kind of people.") Make sure there are plenty of credits, subsidies, and other assorted treats to hand out to the government's favorites (namely, those organizations that make large campaign contributions.) If some upstart tries to move into the upper crust, don't hesitate to levy a new tax on the industry, and then subsidize all the established players. You can always claim that leaving the newcomer out was "an oversight" but make sure the paperwork to get it corrected drags on long enough that they have to close up shop. Make the legislation complex enough that nobody can avoid breaking some rule somewhere. Have contradictory requirements in different sections if necessary (and disguise the fact by making the legal code so large that nobody can actually hope to ever read the entire thing in a single lifetime.) The goal is to be able to remove any politically dangerous individual without it looking like it's being done for political reasons. Keep a list of mentally unstable individuals (especially ones who don't appear unstable upon cursory inspection). Leak them superficially convincing but ultimately false information on occasion so that there are so many conspiracy theories flying around that anyone who even mentions the real conspiracy is immediately labeled as a crank. Mentally unstable individuals are also handy for assassinations if you just drop the right suggestion in the right bar at the right time. Keep the list handy, you can probably use it in the next bit. Whenever people start questioning the system, come up with some "existential threat" that "will kill us all if we don't all band together under the benevolent leadership of the government." Don't hesitate to exaggerate some minor threat and then go bomb a third-world country, the dunces you're turning out of your "education" system won't ever bother to look into it. If that's not convenient, then just use some of those mentally unstable individuals to stage a few terrorist attacks. It's even better if you can first talk them into doing it, and then step in and thwart it at the last moment to show the people what kinds of things you're protecting them from. Keep the masses more scared of other things than they are of you, and they'll never question the system. Finally, if all this doesn't seem to be working, split the ruling class into two or three factions that have the same ultimate goal (maintaining their own power) but have them publicly fight each other over relatively inconsequential details. Just make sure they're never so acrimonious that they won't team up to gang-beat any outsider who tries to move into the ruling class himself. But, above all, do *not* teach any history that has not been modified to make life before the institution of the new system look as horrible and undesirable as possible, and do not teach critical thinking of any form. Doublethink and oblivious apathy are what you want from your people. ]
[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/47406/edit). Closed 7 years ago. [Improve this question](/posts/47406/edit) If tomorrow, scientists discovered humans could all begin to live forever, what new stages of behavior (like mid-life crisis, the terrible twos, three year itch, etc.) would evolve? Already mice have been genetically modified to have their aging process reverse: [Reversal of Aging in Mice](https://www.theguardian.com/science/2010/nov/28/scientists-reverse-ageing-mice-humans) I imagine there would be: * An immediate classifying of the technology as Top Secret, and then withholding it from the public until certain issues were clarified, like: + Birth rates/population densities. + Political stability/dipomacy. + Ethical debates about worthiness/unworthy or wanted/unwanted genetic/personality traits could be dealt with, i.e. mass murders or people with incurable debilitating diseases might not want to be made immortal. + Ethics around voluntary euthanasia would begin to evolve. * In the mean time, the government(s) in possession of the technology would begin drafting scenarios about likely outcomes of the technology on human evolution. Some crux issues might be: + How many people would actually WANT to live forever? Perhaps they would be an extreme minority and thus releasing immortality therapy to the general public would be a non-issue. + New maturity standards: the age of consent, drinking age, voting ages might be different after people begin living for millions of years. + New stages of psychology would be constantly being discovered as humans began to live through them + Retirement age and social security would change. + People would become more socially homogenized the longer they lived due to the increasing number of experiences they lived long enough to experience, meaning on Earth today, there are only a certain number of experiences to be had and yet so many people have not experienced the full range of these experiences. As a result, they cannot relate to each other and fail to communicate and cooperate effectively. However, if people begin to spread out across different planets, their experiences might begin to be more disparate, resulting in greater isolation and hence less likely to be able to relate to each other in a friendly way. + The brilliant minds on earth today would not be lost to death and would continue to drive earth's intellectual development to ever new heights. + People without certain qualities might live long enough to be given better genetic traits through genetic editing. + Other planets or space stations would be investigated for allowing population expansion and political/philosophical differences. + Should dead people be cloned and allowed to grow up again? People like Einstein might be brilliant again if exposed to schooling/training already in accordance with their known predispositions. + Research into human tolerance for different experiences for longer time periods must begin. How long can people stand nothing new happening? What forms of release/recreation should be instituted/made legal? [Answer] > > "Who wants to live forever?" - Queen > > > Forever is a very long time. Most people can throw the word "forever" around without really having to come to terms with just how long of a time it is. The first few stages would be reflections of our current way of living. That's because we have no experience dealing with the curious situation of someone living 200 or 500 years, and its pretty clear that this is something that's too important to leave to mere experimentation. Historically speaking, the solution societies tend to choose for dealing with this is that they reflect their existing society in the new one. Some societies would treat childhood (i.e. to the drinking age) as one region, and adulthood as another. So you would see either a stretching of the retirement age or an oscillatory cycle of working and retirement. Others would see this as a chance to stretch childhood out, ensuring each individual is more prepared before crossing the essential milestone into adulthood. The Chinese have traditionally divided life into three regions based on the Chi (lifeforce) and the Xue (blood). In the young stages, the two are not in balance so one guards against passions which could make them more imbalanced. In the adult phase, they are balanced and not easily subdued, so they guard against combativeness which could break things without warning. In the old age phase, they are more depleted, so one guards against other who might try to "acquire" your power without permission. What does this mean? Hard to say, actually. When your people start living forever, *how* they live forever will affect which phase gets stretched out. If they remain balanced and strong, the Chinese would extend the adult phase. If they merely weaken at a much slower rate, they may extend the old age. It would be up to you to decide how your particular approach work with Chinese Philosophy. However, we've been talking about 200-500 years. How about 1000? 2000? If a human was 2000 years old right now, they could tell us whether Jesus walked the earth or not, fundamentally changing entire religions just by his presence. How about 10000 and getting to experience the creation of writing? Forever is a very long time. Let's look at what they have to look forward to. Many are from [Timeline of the far future](https://en.wikipedia.org/wiki/Timeline_of_the_far_future), a predictive model of things to come: * After 10,000 years you might get to see the Wilkes Subglacial Basin "ice plug" break down. This catastrophic event would raise sea levels by 3-4 meters. * After 100,000 years, the movement of our solar system through the milky way will shift the apparent locations of the stars such that the constellations are no longer recognizable. * After about 1,000,000, there's a substantial chance that the Earth will have been hit by a 1km wide meteor or larger. This is just one step shy of the kind of event that ended the reign of the dinosaurs. * After about 100,000,000 years, we're pretty much certain that an extiction-level impact will occur by this point. Also, Saturn's rings will have degraded, collapsing into the planet. * After 1,000,000,000 years, strange things happen at the plate tectonic level. Due to the changing temperature of the sun, the surface water will boil away slowing plate techtonics enough that voclanos are no longer cycling enough CO2 into the atmosphere to sustain life as we know it. Everything we know about how life sustains itself will have to change to survive. Of course, on the timescales we care about... * After 4,000,000,000 years the fuel in the sun runs out. Those who live forever actually have to consider the eventual depletion of their own sun. * 1,000,000,000,000 years We become very reliant on memory for cosmology because the expansion of spacetime and the effect of dark matter will completely obscure all evidence of the big bang. Beyond this point, we literally will not know where we came from. * 100,000,000,000,000 (100 trillion) years from now, star formation is over. The last of the stars have died out * 1,000,000,000,000,000,000,000,000,000,000 years from now, all remnants of stars which have not been permanently ejected from their galaxy have fallen into a black hole * 1,000,000,000,000,000,000,000,000,000,000,000,000 Matter ceases to exist. This is the scale where current theories predict protons will decay. Note that we haven't gotten near forever yet. In fact, we're really no closer than we started. Forever is an infinite amount of time away, and infinity is really big. To handle "stages of psychology" on an infinite scale, we have to shift our ways of thinking. If we want a finite number of stages, each stage needs to last, well, forever (or at least the ones worth mentioning do). Thus, it might be better to assume that everything from now to proton-death-of-the-universe all fits into one stage of our new existence. Alternatively, we can have an infinite number of stages, and describe them geometrically. For example, we might extrapolate the phases of life for humans. There's the first 3 months, then the first 13 years, then puberty hits and we get another 8ish or so before adulthood. Then there's 40 years until retirement, and roughly 30 years until death. If we try to fit these to an exponential curve, we may be able to build a new set of ever increasingly long stages of life to try to pass the time. We might pick up a binary existence, where life is divided up into potions: 1/4, 1/2, 1, 2, 4, 8, 16, 32, and so forth. Of course, the meaningful portion of this which comes from modern human psychology today becomes vanishingly small. What good is the experience of a few billion creatures that have never had to deal with their thousandth birthday party to a creature which has walked the planet a million years. Certainly we will learn something in that time. > > "Who waits forever anyway." > > > [Answer] An immortality treatment would be an unprecedented historical event, but predicting the events would depend on the actual details, specifically: # Actual Details * Does the treatment **reverse** aging, **halt** aging, or allow **indefinite** aging? + In the first case, we can assume a world of mostly young adults. (If the treatment reversed it all the way to childhood... then it would either not be used or the planet would quickly be depopulated as people aged into infancy and starved.) Either the treatment is administered on a rolling basis, or administered to deliver an optimal age point, in which case in the long run the effects will be roughly equivalent to the halting case. + In the halting case, does it halt all biological development? This is hard to imagine, but vampire-genre novels give us a lot of thought-fodder for this. At the least, we can assume that young adults would go a very long distance to take the treatment in their prime. (Think college costs a lot today? Same situation only MUCH more expensive: potentially a new form of slavery.) + In the indefinite case, what happens as your body breaks down but refuses to die? Does the majority of the population become indefinitely living but otherwise disabled elderly? * Who discovers the treatment? + Private Industry: Depending on how they understand it and roll it out, this could either become a black-market situation (avoiding government control), an elite-class only situation (where the cost of or access to the treatment is only affordable by few), or a new-slavery situation (where the societal constraints placed on those who receive the drug are staggering to the degree of entirely controlling the recipients life through one mechanism or another). + Government: An attempt to keep it secret is likely, as it provides a substantial advantage over other nations. (Note: 'Top Secret' is not actually that high a classification in many places.) However, without administering it, the treatment does no good. So it can't stay secret forever, or even very long. It is also a mistake to assume that revealing it would be the result of 'clarifying issues' so much as 'seizing an advantage'. What would be guaranteed is that whatever ruling class in power existed would attempt to legislate it such that they kept the power for themselves: potentially divisive in a democratic country. + Research Institute: In the modern environment, it's hard to see how this wouldn't quickly become a 'private industry' scenario, but one might see how an MIT-like lab would release the information broadly and you'd have a wide range of competitors in an unregulated state trying to recreate and administer the treatment. This would cause a lot of political chaos, but also probably the most egalitarian and wide uptake of the treatment by those currently living. * Complementary technologies: + Would birth control become mandatory? Population spikes are absolutely expected in any other scenario, and food and energy production would be immediately strained. + Financial instrument reinvention: if people live forever and are *not* productive forever, the industrial support for those people would have to be radically re-imagined. If those people *are* productive (hold jobs), the system would still have to be re-invented but along different lines: a lot of insurance would become untenable, for instance. Life insurance notions would have to change. Retirement funding becomes an entirely different beast. + Regardless of a population halt, energy usage could be expected to continue to expand as people accrue more and more things that demand it. # Projected Psychology Shifts * Voluntary Suicide: It's possible that you'd see an increase in this, but there is no particular reason to think that the ennui of life would actually increase in absence of another driver (such as being enslaved for thousands of years just to afford immortality, or being driven to lower and lower standards of living because the wealth gap continues to increase). * Maturity Standards: Unless there is a 'higher' level of maturity (and is there really any evidence there is?) to reach, it's unlikely that notions around what age it's ok to start voting/drinking/etc. at. Most human brains are fully formed at 25, so unless that development continues, '25' is certainly old enough and there is no reason to delay longer. In this scenario, given that the difference between 18 and 0 is meaningless to someone a million years old, there is no reason to bar voting on that count: such a small slice of the population even falls into that bucket that prohibiting it becomes really an exercise in wasting energy. (If that bucket exists at all: is the population still growing? That is the much bigger issue.) * Most people would want to live forever. There is no reason to think they wouldn't: the bigger question is if they would forget what death is, and if that would have a bigger impact on society. How is empathy affected if the most major painful thing never (or rarely) happens? If your brother of a million years suddenly dies, how are you adversely affected? Does risk-taking increase or decrease as people become pathological about it? Does the belief in higher spirituality wither because no afterlife is likely to be in the cards? * There isn't a clear notion on whether humans would mix more or less. The excuse to 'travel now lest you never get the chance' disappears, but the need to 'stick around lest you miss something' also disappears. Chances are this works out even on balance: those who mix with other humans will continue to do so, those who don't, don't. More difficult is generational gaps: unless the population is stable, those who grew up in a world with death will be very different from those who grew up when death was conquered a millennia earlier. * Educational changes would be pronounced: there is no reason not to become an expert in dozens and dozens of fields before you even hit the workforce. A more pronounced problem would be the aging of knowledge you learned early before you are in a position to help yourself. Without compensating learning and educational technology and technique, humans would be both pushed to know many things (they have the time to learn, after all), and be constantly falling behind. The limit to how much one human can know at a given time would likely be quickly found and optimized for. (Well, 'quickly', in that it would be a small percentage of a lifetime.) * Presumably technology will progress, and humans will be encouraged to use more and more of it. Gene therapy. Cybernetics. How long until a human is unrecognizable given all the augmentations they've had? Evolving in this manner becomes almost necessary, lest you are left behind by those who do. * Lacking a young-brain learning curve and hormones, will creative thought be stifled over time as people learn what they like and get stuck in a stasis with just that? * At the rate of one scar every five years, how long until humans look like they've been mauled by a bobcat sent in an Amazon box? * Less than needing to be conditioned to deal with 'nothing new', humans would have to be conditioned to deal with everything being 'constantly new'. The world a human grew up in will be a dusty, distant memory for the vast majority of their lives - assuming they even remember. How many years can the human brain go and still hold on to even one memory of childhood? * What does the death rate actually become? Even if you will 'live forever', that doesn't mean you can't die: some rate of accident, homicide, disease, planetary impact, and heat death of the universe will still occur. Is the expected human lifetime actually 'forever', or is it only a couple of centuries? In the US the rate of accidental death is [41.3 per 100,000 according to the CDC](http://www.cdc.gov/nchs/fastats/accidental-injury.htm). Assuming a similar rate, only one human out of every hundred would survive even ten thousand years. * Diversity would increase, not decrease. This especially includes psychological diversity as people have more opportunity to experience more paradigms and be shaped by them. Some part of the populace will never get beyond a certain point, getting mired. Some will see new vistas as they are given time to work through various traumas. Because the number of 'rolls of the dice' will happen, simply as a matter of having more time, more people will be weirder and weirder and have more and more unique paths - simply because their histories are longer. Someone who started out as a government worker could a thousand years later be an entrepreneur. While convergence around a given set of widely experienced paradigms would occur, the standard deviation would be much larger. People are weird when you can bound them in a hundred years worth of history, development and life. When they are unbounded they will only be much, much weirder. [Answer] Well it hard to predict the literal infinity of live stages that could take place in forever, I think that humanity would have to deal with some form of "immortality depression" The long you live the hard it will be to adjust to the changes take place in the world and the more likely that you life is going to take a bad enough turn that you would consider suicide. Especially if your love one weren't immortal like you. I can predict that most of your immortal people would go thorough at least one stage of depression. [Answer] ## Grumpy old bastard Seen everything, been there, done that, nothing new in the world and it was all so much better when I was young but it was uphill both ways to school you kids have it so easy these days and don't you dare change anything, it's not broken so don't fix it... --- This of course leads into the immortality depression and eventual probable suicide by increasing risk taking. There's a lot of work to be done on the brain before mere physical immortality will be psychologically viable. [Answer] Check out Michael Moorcocks *The Dancers at the End of Time* Books. The immortal society who inhabit the Earth only a few tens of millions of years into the future, possess technology capable of easily converting matter into energy and back again with a really user friendly interface (thought). There is nothing they cant do. But there arent many of them left, no one has come into existence through birth for a long time, and there have been a few internal conflicts as well as an interstellar invasion (aliens trying to stop humans from converting all the matter that matters). The few survivors are ravaged by what we would call mental illness and they are inclined towards suicide. Dystopia caused by immortality and virtually limitless energy and technology. ]
[Question] [ In my world, I want to create cultures resembling cultures of old Earth ages. This applies both to state structure and culture. (e.g. ancient Egypt revival) Since this does not happen spontaneously, I ask you: what causes subcultures and cultural traits to appear? Hippies appeared because of war (Vietnam), punks appeared because of oppression (and conservatism), same for rock'n'roll and metal, several art branches appeared as trying to make something new (Picasso, postmodernism, etc), several ideologies appeared to help the weak and injured ones (nacism, communism, several sects and religions, and so on), what else can be a factor? [Answer] One thing to consider about cultural phenomenon like rock'n'roll and hippies is that they rise out of cultural mixing. Rock'n'roll for instance grew out of rythm'n'blues and country, or rather out of black culture in america mixing with white poor culture. From there you can go on to say that it grows as a way of young people looking for a way to be in opposition to the the established structures, but it doesn't originate in that drive. Hippies also didn't appear because of the Vietnam war, they arose from beatnik culture and a new western fascination with eastern spiritualism. Similar things can also be said about older cultures, where it seems again that interesting things happen when people meet. Consider for example what happens when early Christians travel to Greece and Rome to spread their faith and mix with the cultures they meet. Christianity goes from being a small, eccentric mystery cult to a sophisticated and state sanctioned religion in a relatively short time. Another thing to consider is how cities and states grow in relation to trade routes. For example, the biggest cities in the UK were the port cities. This is also where cultures mix and interesting things happen. Another earlier example is how presocratic philosophy has been theorised to have grown out of culture melding in the Mediterranean area. It is when we meet other people that do things differently than ourselves that we gain the ability to question how things have been done in the past. This is important to consider when it comes to youthful rebellion and cultural differences between the classes, if the difference is more than how much they drink and how foul the language is, then the inspiration had to have come from somewhere. And also furthermore people who adopt traits and aspects of somebody else's culture stands a lot freer to change it through their interpretation and desires than the original holders of the culture. Take the high heeled shoe for instance. It originates from Persian riding boots used by men and was imported to Europe as a masculine fashion, worn even by kings. But in Europe it was first and foremost a fashion and as such it wasn't bound in interpretation by traditional use. The shoe was kept, the idea behind if mostly forgotten. Similar things can happen with musical traditions or ceremonies when they are taken up by new people. [Answer] A Subculture will appear because a group of people who have something in common want to distance themselves from everyone else, or at least the majority or a certain other group of people. Young people feel the adults don't respect peace and are too warlike? You get a peace movement that may very well adopt music, clothing and even language styles to identify with each other and set themselves apart from those warlike others. Fans of a band or music style want to express their fandom stronger? They start dressing like the musicians they like, maybe behave like them, favour the food that's advertised by those musicians. Rich people want to make sure everyone knows they're not like the riff-raff? Send the kids to private schools, don't use slang words, dress like the noblemen of the last century. However big or small the thing that binds the group together initially is, all that's required is the desire to show that these people as a group belong together, and everyone else is not part of it. So if you wanted to bring back ancient cultures, the routes I'd recommend would be: * The upper class wants to REALLY set themselves apart from the unwashed masses, and clearly ancient rome was a time of enlightenment (or greece, or whatever you want to use). So they start wearing togas and lounging around on roman-style couches on their parties. The more dedicated (or eccentric, or crazy) will start dressing like that outside of those parties too, setting an example that others follow. Some upstarts want to show just how much they're IN and start making their butlers and housekeepers dress as slaves... * In protest and mockery, a band dresses themselves up as egyptian gods and produces a music video where they whip slaves building pyramids for them, or something like that. Young people who are already annoyed at the 1% and their decadence jump right on that bandwagon - cool kids start getting hieroglyphics tattooed, the even cooler kids start dressing up as pharaohs, slaves, slavedrivers and whatnot - to protest at first, to belong and because it's cool later. ]
[Question] [ This character is an elf-human hybrid, who can travel long distances at high speeds with little rest. She can run at top speed (what we call *sprinting*) without stopping to rest, sleep or eat for three days. It is generally accepted that elves are very hardy and fast, case in point: Legolas from Lord of the Rings or Arya from the Inheritance cycle. My question: How would an elf or an elf-human hybrid gain the energy he/she needs to run such long distances, at such high speeds, without rest, sleep, or food? The energy needed must come from somewhere, but the concept of an elf needing to gorge on mountains of food to keep up his strength seems a bit vulgar. On the other hand, elves don't have slow metabolisms: I've never heard of a fat elf... [Answer] So, elves are creatures that are rather heavy on magic, so this sort of feat is not a big deal if you just answer - "hey, it's magic!" But that is a cheap answer... unless you stop to realize that what you are asking really goes to the question: how can magic happen and still follow conservation of energy? Basically, we humans store the energy we get from food in these molecules called Adenosine Triphosphate (ATP). But any being that would be able to perform feats like this would have to use a different way of storing and freeing up energy - a different molecule that could store up a lot more energy, and a lot more of it. According to Wikipedia, we only have about 250 grams of ATP in our body, but turn over the equivalent of our entire weight, worth of ATP, in one day. That seems hard to believe, but gives a good gist. Imagine a being that has as much as a kilo of Adeno-TriHeptose-Pentaphosphate, and can turn over five times her body weight of it in a day. ATP is adenine with two molecules of C5H10O5 and three phosphates. This molecule i am making up, ATHPP (probably cannot exist) is Adenine with three molecules of a much more complex sugar (C7H14O7) and five phosphates. This being is basically a walking gas can - no smoking in her vicinity, please. By the way, adenine is used to control heart rythm, if I remember correctly, so the additional adenine would help explain why his heart-rate does not go through the roof when he uses that much energy. Also, the vast storage of sugar also explains why they are not much affected by alcoholic drinks. You don't need lots of food, you mostly need highly concentrated sugars. Equip this gal with a pack filled with momma's special recipe syrup, and let her rip. [Answer] Alright. Brute-force is not very Elfish, so i'll go with a more clever and nimble solution: Energy efficiency. * Part 1: Staying alive If our elf uses as many calories per km as a human sprinting, she will overheat and die very quickly. If she has speed and caloric mileage comparable to a human marathon runner, she will face the same thermal challenges, which means she'll have to wear very light clothes, leave the mithril mail at home, and require frequent hydration, including salts and electrolytes. This is independent of her endurance, stamina, etc. The volume of water a person can sweat before dropping isn't that much. So, higher metabolic rate isn't the answer. Also, as explained by James, higher power output creates more waste the body has to get rid of. She will need to do it with **less energy** that a human, which boils down to: how to make running more efficient? * Part 2: Biomechanics When we humans run, most of the energy is consumed in raising the center of mass of the body once per step, and this energy is not recovered when the center of mass is lowered again. Very little energy is expended towards overcoming air friction. This is why someone in decent shape can ride a bicycle at 20km/h with less than 100 heart rate. This is a barely noticeable effort which can be sustained almost all day. Can't be compared AT ALL to running at the same speed... Running at 20km/h should require 2-300 watts of mechanical power, which due to our efficiency of around 25% translates to about 800-1200W input chemical power (ie, food)... and output thermal power (ie, heating). Now, let's draw inspiration from an amazing animal: > > As red kangaroos hop faster over level ground, their rate of oxygen consumption (indicating metabolic energy consumption) remains nearly the same. This phenomenon has been attributed to exceptional elastic energy storage and recovery via long compliant tendons in the legs. > > > [source](http://www.sciencedirect.com/science/article/pii/S0305049198000224) So, kangaroo have KERS (Kinetic Energy Recovery Systems) like F1 cars. Let's equip our Elves with a few elastic tendons in their legs. Now, picture an elf running. When the front foot touches down, the knee and ankle joints flex, and the springy tendons store energy, which is then recovered to propel the elf forward on the next stride. Just like kangaroos. Springy tendons also reduce the strain on joints and muscles, which is important for long distances. Plus, this should give our elf a nimble, agile and quiet gait, which is very in-character. Since Elves make the best swords and the best gear, they also make the best shoes, so she'll have blister-proof Fantasy Air sneakers. Let's also give her an elvin agility bonus, and fudge this to 50% energy savings. We're down to 100-150 watts, which is still a bit less efficient than a mountain bike with big knobbly tires, but a lot better than before. Now, we give another elvin bonuses: * Increase metabolic efficiency to 35% instead of the human 25% * Optimize metabolism to burn fat more efficiently than humans. She still produces 100-150 watts mechanical. However, increased efficiency means she needs to burn less calories to do so, therefore sweating a lot less, and needing less water. She doesn't need unrealistic lungs or heart either. She will also burn mostly fat. So, she needs 40 grams of fat per hour, or 30 grams fat plus 20 grams sugar. Pastries (ie, Lembas) should be fine. **Reducing** (not increasing) her metabolic needs seems to be the way to go. Fat will carry her much further without eating, as body fat reserves are quite important (even for someone who looks like a stick figure) whereas sugar reserves are not. Now, some of that energy could also come from a magical source, of course. Or her magic could help with the pesky logistic details, like joint pains, blisters, etc. Just don't make her run for a week in plate armor. Summary: Elves are more efficient, thus use less power, and as a result Legolas arrives at the end of the trip with fabulous hair, looking relaxed, and without breaking a sweat. Meanwhile, the dwarf sweats gallons in his heavy armor, stinks, and blames it all on the elf. [Answer] Since you already referred to Legolas, I would say your Elves found the recipe to make *lembas*. A special type of biscuit that is extremely nourishing and can sustain a Elf or Human for an entire day. Some care must be taken though as Merry and Pippin found out. If you combine it with Entish drinks some strange things may happen... Seems your runner will be fine if she just eats a bit more if this stuff than is normal. [Answer] Well, first I would say that Elves would need to have an incredibly efficient metabolism, Allowing them to use less energy to perform similar tasks to others. On top of that part of the efficiency is magic based. It works at a subconscious level. And the elves tend to regenerate this magic store when around areas that resonate with their nature. Tree elves rejuvenate in forests etc. They could also perform rituals to help speed up the process or to work in place of a physical setting. But the magic helps fuel the body, keep fatigue away and repairs minor damage from the exertion. Well fed elves will use less magic to perform the same tasks, and eventually an elf will hit it's limits if it can't fill up it's reserves. [Answer] Welcome to the site ASH, I think you are probably stuck with a magically enhanced energy creation, storage and usage system...not to mention clean up. The system humans have in place it incredible elaborate. We have systems specifically designed to provide nutrients and oxygen while simultaneously removing cellular waste and we are nowhere near efficient enough to run at a sprint for three straight days. **Problems** --- * Caloric intake versus burn. A marathon runner, who is not spriting, will burn roughly [100 calories per mile](https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&uact=8&ved=0ahUKEwiVm_766PzLAhUoyYMKHUXBBhIQFggfMAE&url=http%3A%2F%2Fwww.theactivetimes.com%2Fhow-many-calories-does-running-marathon-burn&usg=AFQjCNEqIB2uExZKW9Wgy8v0vfDRzQ9AmA&sig2=32i2czLfFieq11803-cs6w&bvm=bv.118817766,d.amc) during a race, which roughs out to 2600 calories for a full marathon and on average a marathon is run in around [4 hours and 20 minutes](http://www.theguardian.com/lifeandstyle/the-running-blog/2015/apr/21/marathons-by-numbers-running-the-data). This puts your elf/hybrid caloric burn at something like, **46,800 calories** for your three day jaunt. To manage that you would have to eat 86.32 big macs. *Keep in mind, this is not at sprinting speed...this is marathon pace* * Waste removal. When your body burns its fuel it creates waste, when it burns a lot of fuel quickly it creates more waste than it can process and goes into [oxygen debt](http://medical-dictionary.thefreedictionary.com/oxygen+debt). There is simply no way a human, or purely biological system could handle moving that much for that long. Those are the two biggest, most directly related problems, but there are others as well. The cushioning systems between bones and the strength of the bones themselves would have to be improved. Lungs would need to be larger, and the heart bigger. Exhaustion has impacts on coordination and balance not to mention its impacts on cognitive function. Oh right and muscle fibers would have to be vastly improved...stronger, more flexible, etc etc etc. **In short, the answer to your question is a magically enhanced metabolism.** ...but *in short* is boring. :) [Answer] This is actually not that surprising of a feat. Tolkien's elves are exceptionally lightweight (magic) and humans are one of the best endurance animals in existence, so combine the two and the feets makes sense. Elves are described and shown to be exceptionally light weight (one book describes them as walking on top of soft snow without sinking) magic is the only given answer as to why they are so light, but that alone would make for some very big feats of endurance since they are moving less mass around. Real world humans have exceptional endurance, remember the tour de france used to be a 6 day foot race and **Dean Karnazes ran for 3 and half days without stopping**. Normal fit humans can walk a horse to death and as shown trained humans run for days without stopping, sleep forces them to stop before anything else. Part of this is becasue humans are built for endurance but part of it is also that human have exceptional willpower. now combine exceptional endurance with a body so lightweight sprinting is not any harder than walking and your described feats seem quite reasonable. [Answer] There isn't really a magical way to gain **more** energy. Not without using magic, anyway. Instead you just use the energy more efficiently. Humans are already more efficient long distance runners than most animals, so I'll just pick on some specific points. **Aerobic metabolism.** Better lungs, better blood circulation, more haemoglobin, more mitochondria, better sugar storage, and changes to metabolism and enzymes to support the above. Most of this would simply be human+ and fairly self-explanatory. And irrelevant unless the character gets captured by a mad scientist. But lungs is something there you could do a significant improvement and get a significant boost. [The best model to copy would probably be bird lungs.](https://en.wikipedia.org/wiki/Bird_anatomy#Respiratory_system) **Reduced weight** Less weight to carry, less energy wasted. Elves are usually described having slender builds anyway, so that is a no-brainer. If you use the avian lungs option, you can also copy the hollow bones. And should as they link with the respiratory system. This is naturally pointless if you then strap on massive armor, but elves should weight less than humans. **Heat management** Excess heat and getting rid of it is a major source of long term inefficiency for humans. I'd suggest using the improved lungs to get rid of more heat and sweating less. Another **easy** (not really, but it is easy to write) adaptations is to make elves tolerate variable body temperature. 36°C/97 F when standing still, up to 39°C/102F when exerting themselves. This should improve efficiency in both modes. You could make the variability smaller for the head by adding extra blood flow control on the neck. You could also make the hair double as heat radiator to help cool the head while running and justify some exotic hair colors. (The hair would have better heat conduction and the scalp would have a "thermostat" to control heat transfer to the hair.) [Answer] A tall order, this 3 day sprint with no rest. She is going to have to drink and she is going to need salt. Here are my ideas about the rest. 1. Long distance running. There is nothing better than humans at long distance running. Animals beat us for strength and speed but a human can run down just about anything given time. <http://www.slate.com/articles/sports/sports_nut/2012/06/long_distance_running_and_evolution_why_humans_can_outrun_horses_but_can_t_jump_higher_than_cats_.html> We will say her human dad was a champion distance runner with all the oxygen deliver, slow twitch muscle etc that entails. 2. Liger principle. Your hero is a hybrid. Sometimes in a hybrid, genes which mask or reduce effect of a gene are not transmitted meaning the gene is unsuppressed in the hybrid. In lions, contributions from the male increase size and from the female limit size. If the mom is a tiger there is no size limit contribution. The result: ligers are huge. <http://blogs.discovermagazine.com/gnxp/2009/09/why-ligers-are-huge/#.WMiNABiZMk8> Humans are weaker than other apes because of some issue with our muscle - it does not activate as thoroughly or completely as is the case for chimps. The linked article suggests that this contributes to fine motor control; ok. Another theory is that loads of brute force at the ready increases the chance of killing a baby by accident and weakening humans makes babies safer. Just as the tiger is genetically distant enough from the lion that growth enhancing genes are not masked, the elf is distant enough from the human that genes allowing maximal muscle use are not masked. The sacrifice is that you lose the fine tuned muscle activation that lets humans do delicate tasks. So she is a little awkward. But freaking burly! 3. Elves run higher hemoglobin levels. Why? Elves have diverged less from the aquatic common ancestor of elves and humans and are adapted for breath holding. Elves notwithstanding, the idea that humans were aquatic apes is a cool one. [https://www.amazon.com/Scars-Evolution-bodies-about-origins-ebook/dp/B00844ORDK](http://rads.stackoverflow.com/amzn/click/B00844ORDK) Higher hemoglobin means better blood delivery, especially in sprintlike conditions. It will take more for her muscles to go anaerobic. That is why athletes do blood doping. Her hemoglobin of 19 means she is not going to be vanilla fair, if she is white-skinned. More the ruddy glow of health (and lots of blood). 4. Her sprint is not really that fast and so she does not really get to anaerobic (which is unsustainable for 3 days). Partly because of the burly. Also because of #5. 5. She is fat. In all the right places and the other places too. She was never a skinny girl, but the current degree of fatness is your fault, ASH-Aisyah and she is not pleased with you. But if she has to be able to run 3 full days without eating that fuel has got to be on board somewhere. To clarify she is not a bouncy Venus of Willendorf fat but fat like a seal; fat everywhere. See #3. Your half-elf is an even better swimmer than she is a runner. 6. She is drunk. You prohibited eating but not drinking. Humans need more water that most because our perspiration, wasteful when we are not moving fast, is key to keeping cool during prolonged exercise. You need something to sweat out. Additionally, sweat costs salt, which is why distance runners should not drink pure water but water with electrolyte. But she is drunk because her drink is a salted 40 proof spirit, invented for exactly this purpose. The ethanol is excellent fuel, comparable to fat in energy density and will not cause her to break the ketogenic state she needs to burn her fat for energy. 7. She is naked. Your hero is proud of her own skin, and clothes are wasted weight. Plus extra surface area for sweat helps the cooling. 8. She smells terrific. That salted spirit is flavored with special herbs that come right out thru the pores, like cinnamon schnapps or garlic. But these elf herbs smell more like green Chartreuse crossed with Old Spice. 9. She is high. Those herbs work like coca leaves, which is how she can do the 3 days without sleep. Your ruddy, muscular, clumsy, overweight, naked, drunk, high, great smelling elf/human hybrid. Oh yeah! She will run you into the ground. ]
[Question] [ There it is. The elusive **Ersa 772**. Filled with an estimated $15 trillion in precious metals, mining that asteroid could make you the richest man on this side of the galaxy. You have all of the funds and resources you need to get your hands on that asteroid: a crew of 20 veteran astronauts and space explorers, 100 billion USD in funds, and all of the technology needed to extract the metal from the asteroid. Assume 22nd century technology, and assume that something like a space tent has been invented, and it can moderate temperature, and hold about 50 people comfortably for about 10 years because somehow future humans have solved the problem of sustaining humans in space for long periods of time. There's just one problem: you don't have a spacecraft to get there. However, you're in luck, as your chief scientist informs you that asteroid **Chariclo 101**, which is about 200 miles in diameter travelling at about 60000 mph, is expected to come very close to impacting **Ersa 772**. Would it be feasible to hitch a free ride on **Chariclo 101**? Remember, we have a "space tent" (which takes up about 1.5 square miles) that can sustain humans, so is there really any reason this wouldn't work? **Edit:** Hope this helps [![Solar System diagram showing current and future positions](https://i.stack.imgur.com/E2XZn.jpg)](https://i.stack.imgur.com/E2XZn.jpg) [Answer] ***Feasible, but inefficient, and needlessly complicated.*** It costs more to change orbits to rendezvous with Chariclo, then change orbits again to rendezvous with Ersa, then to just go straight to Ersa. Why? Delta-V and inertia. Your setup has a few problems, you say Chariclo 101 is going 60,000 mph, but ***relative to what***? The Earth is going around the Sun at 66,600 mph, so you probably don't mean orbital velocity. From your drawing it looks like Ersa is making about 1/6th its orbit during the trip. Asteroid belt objects have an orbital period of about 4.5 years which means the trip will take about 275 days. The details don't really matter, there's an asteroid whizzing by your starting point that will later whizz by your stopping point. The problem with your plan is velocity is not the problem in space flight. Once you're up to speed in space you can coast along pretty much forever. ***Changing velocity*** is, and your plan just adds more changes. Not just absolute velocity, but also direction. This is known as [delta-V](https://en.wikipedia.org/wiki/Delta-v). This means changing your orbit costs fuel, and each rendezvous requires delta-v. ***Even in the 22nd century delta-V matters*** (and if it doesn't, why do we need this convoluted plan?). Then there's the issue with your spaceship. ***Any spaceship which can rendezvous with and land on Chariclo then ride it to Erza, can more easily rendezvous with and land on Erza.*** You need a spaceship large enough to carry all your people and all their supplies for the trip and mining colony. You need fuel to leave LEO and rendezvous with Charicio, plus fuel to leave Charicio and rendezvous with Erza. You need supplies for the trip. If you already have a spaceship large enough to carry everything and everyone to Charicio and wait until it reaches Erza, why not just take it all the way to Erza? To sum up, the Chariclo plan means you have to... * Leave LEO in a spaceship sufficiently large to carry all your people and consumables for the whole trip. * Go to where Chariclo 101 will be. * Change velocity and direction to match its orbit and rendezvous, ***which means you're going as fast as Chariclo***. * Find a suitable landing spot. * Land on it. * Set up camp. * Wait and consume resources. * Tear down camp. * Lift off from it. * Change velocity and direction to rendezvous with Ersa 772. * Find a suitable landing spot. * Land on Ersa 772. * Set up camp again. * Start mining. All that extra changing in velocity to rendezvous and land on Chariclo is unnecessary. Just take a more efficient direct transfer orbit to Ersa in your spaceship which already has to hold everyone and everything and already needs the fuel to have the delta-V to reach an object which will pass Ersa. * Leave LEO in a spaceship sufficiently large to carry all your people and consumables for the whole trip. * Change velocity and direction to rendezvous with Ersa 772. * Wait and consume resources. * Find a suitable landing spot. * Land on Ersa 772. * Set up camp. * Start mining. This allows you to pick a more efficient, direct transfer orbit, and at the time of your choosing. It removes the cost and complexity of an extra rendezvous, landing, and liftoff. This assumes there's no consumables on Chariclo. If there are (such as mineable air, water, fuel, and reaction mass) it *might* make the landing worthwhile. If you can "live off the land" for the 9 month trip it will greatly reduce the amount of supplies your spaceship must carry, and thus reduce its size and complexity. [Answer] ## Schwern's answer is the correct one for the specific question that you asked. However, there is a situation in which something similar to what you describe might be both feasible and desirable. ## [Aldrin Cycler](https://en.wikipedia.org/wiki/Mars_cycler) ### The problem Space is very hostile to human life - deadly radiation, zero-G, energy production, food production, oxygen production, water production. Also the general environment of space habitats leave much to be desired from a psychological perspective - living space. The reason those things pose such hurdles to space travel is the fact that every gram you take with you often costs 2 grams (or more, sometimes much more) in fuel you need to bring with you for your mission. ### The solution Imagine a situation in which you could bring as much mass as you wanted for your mission without it costing you anything in your fuel budget. > > Aldrin proposes a pair of Mars cycler vehicles providing regular > transport between Earth and Mars.[3] One cycler would travel an > outbound route from Earth to Mars in about five months. Another Mars > cycler in a complementary trajectory would travel from Mars to Earth, > also in about five months. Taxi and cargo vehicles would attach to the > cycler at one planet and detach upon reaching the other. > > > ### When to use it When you plan to have a series of missions between two orbits in a Stellar System, you could set up an orbit that cycled between those two orbits. Your cycler would contain all the massive equipment required (or desired) for long-duration space missions (radiation shields, closed loop life support, centrifuges, extra living space, etc.). The cycler would NOT perform any maneuvering (other than perhaps minor station keeping) and therefore, would not require much fuel for changing its $\Delta V$. A mission taxi would launch the crew and time sensitive cargoes to the rendezvous & dock with the cycler. The crew would live on the cycler on the outbound/inbound portion of the journey. The mission taxi would provide the $\Delta V$ required to put the crew and cargo into a capture orbit around the destination. The mission taxi could bring limited shielding, life support, etc. The over all mission might save tremendous amounts of money by doing things this way but only if they planned on repeated voyages between the two bodies. [Answer] Schwern and Jim 2B have staked out the problems and possible solutions to your question, so I will add the main reason your protagonist might want to go with this plan: you need other resources. Landing on Chariclo 101 gives you the ability to not only burrow into the asteroid for protection, but while you are on your way you can mine this asteroid for water, volatiles for the life support system and structural materials. If you have planned this properly, the initial expedition could be travelling "light" and build and stockpile much of the equipment and materials needed for the main mining expedition. Consider that to send a fully equipped mining expedition directly to the asteroid and back requires fuel to accelerate to the asteroid's orbit; match orbits; accelerate back to Earth and then decelerate to LEO at least. Mining water for rocket fuel means you only need to bring enough fuel to get to Chariclo 101, a huge saving in mass. The same considerations hold for everything else. A direct shot to the main asteroid would require the Battlestar Galactica sized vessel, while mining Chariclo 101 could allow you to get away with a far smaller ship. ]
[Question] [ Aka: What I am asking is: what are the basic elements a society capable of space travel needs? What key factors determine a species'capacity to become spacefaring and what cultural and societal aspects are required to become a spacefaring society? [Answer] The short answer: Whatever you want. We have no real-life experience with spacefaring civilizations, so we can't say for sure what needs to be done to get there. The longer, more speculative answer: **Resources:** A civilization that formed on Europa (probably) wouldn't have the raw materials needed to reach the Space Age, so they likely couldn't actually build a rocket even if they wanted to. **Biology:** Kind of a looser restriction, but it would be a lot harder for a race of intelligent aquatic life to reach space, simply because they'd (probably) need to launch a lot of water to breathe in. The ability to breathe a gas is helpful in that regard. **Some measure of planet-wide peace:** A constant state of war doesn't seem to lead to large-scale space travel. If you're always at war with someone, you don't want to give them a big target with a predictable trajectory. **Decent computing power:** Yes, yes, we've all heard how the computers on Apollo 11 had less computing power than your cell phone. That doesn't mean that doing everything manually is always a good idea. More powerful computers can automate a lot more of the repetitive work, making space flight easier. **Willingness to take risks:** It doesn't matter how many tests you run, at some point there will have to be a first person to strap themselves on top of thousands of pounds of explosives to hurl themselves into space. There will always be risks inherent in doing that. As such, a risk-averse species might never make it to space. **Curiosity:** You could have all the resources in the world, but if you never play with them to see what happens, you might never learn that rocket fuel can burn. Also, you would need some measure of curiosity to even want to build a rocket in the first place. [Answer] Several Options (best when they're all together) **Resources** - When there are at least enough resources to stop chasing food, and start innovating, then technological advancement for an intelligent species can take place more rapidly. Also, you'll need the resources to physically get you off the planet. **War** - Part of the reason our space race began with Sputnik and Yuri Gagarin, was due to the Cold War and rigorous technological competition between the world's two superpowers and their allies. **Desire** - When there's a delicious planet nearby, and theirs is really rather dull and filling up, your people will start trying to figure out how to go there. **Dreams** - Long before our space race we as a species looked to the heavens, dreaming of flying, then dreaming of going to the moon. **Compatibility** - If your intelligent race is not "life as we know it," and are able to survive in space and they survive on an asteroid or small planet, it's not long before they can get the technology to get into orbit and beyond. (Okay, this one was a stretch) [Answer] The other answers here pretty much sum it up rather well, but I would like to add another characteristic: **The everlasting need to have more than what one has.** Societies and individuals both want to have more. You can observe it with businesses, billionaires, and Minecraft video game players that want to have more raw ore. Pick your poison - people seem to be very interested in *getting to that next step.* It's the entire basis behind the [Kardashev scale of civilisations](https://en.wikipedia.org/wiki/Kardashev_scale). Going into space gives you access to all kinds of resources, such as the [helium-3 isotope on the moon](https://en.wikipedia.org/wiki/Helium-3) or an [asteroid with 20 trillion dollars worth of platinum, iron, nickel, and cobalt.](http://mashable.com/2012/04/26/planetary-resources-asteroid-mining-trillions/#AOaydbFBI5qC) And the great thing about technology is that reaching the next step helps you to reach the step after that, and so on. Building computer chips out of silicon, and using computer chips to calculate how to reach the moon, for example. It's all about leveraging current technology. A cultural and societal mindset centered on undertaking and progressing to that next step will invariably make one's society end up in space. It's basically inevitable. [Answer] Probably the simplest marker for a true spacefaring civilization is the ability to move through space and use the resources that exist wherever you go. This is analogous to a seafaring society in the sense that the seafarers can travel to distant lands and conduct whatever activities they choose. A non seafaring society might have fishing fleets, for example, but the ships come back to shore every night to replenish and prepare for the next day's work. Our own civilization is much like the fishermen in the second example, we can go out to sea for a short time, but have to return to shore eventually. When our ships can travel to the moon or asteroids and take on local materials to refuel or resupply the life support system, then we will be about 80% of the way to a true spacefaring society. At that point we will be somewhat like the Vikings, capable of crossing the Atlantic for expeditions and plunder, but not really capable of doing too much more on the shores of "Vineland". The final steps to a true spacefaring civilization will be when there is economic justification to go there, and people can go across the void to settle, trade or build now settlements and industry (much like the second wave of people to reach the New World starting in the late 1400's). In terms of time, we are pretty close to figuring out the technological tricks needed to become "Space Vikings" and at least visit distant shores for short periods of time. Discovering economic justifications to actually settle space and become a true spacefaring civilization may take much longer; despite decades of research and speculation, there are still no compelling economic reasons to actually go to space. [Answer] Imagine a society that knows for sure, **the expiration date for the planet on which they live**. Let's say for example that scientists have predected that this planet will be destroyed due to a huge natural disaster in about 150 years from now, this will eventually lead them into becoming more interested in space travel and the possibility of finding a new habitable planet out there, in order to ensure the survivor of their kind. So **the fear of extinction** is a motive for a society to become spacefaring. [Answer] One requirement: The ability to see the sky. A planet with an opaque haze, or a race that perceived using something besides light might not be aware of space. ]
[Question] [ In these two questions, <https://physics.stackexchange.com/questions/232141/how-much-force-would-be-required-to-destabilize-the-moons-orbit-enough-for-it-to> and <https://physics.stackexchange.com/questions/232563/how-much-force-would-it-take-for-you-stop-the-moon-from-crashing-into-the-earth> , I asked how much force it would take to destabilize the Moon's orbit enough for it to crash into the Earth, and how much force it would take to stop it from crashing into the Earth. Now, let's assume that the Moon DID crash into the Earth, but Earth's politicians banded together and mustered the strength to slow down the moon so that it touches the Earth softly (using the sheer power of rhetoric, insincere speeches, and flawed logic). **What would be the long-term effects, environmental, political, and geographical, of the Moon being constantly in contact with the Earth?** Now, let's add a(nother) wrinkle to this problem. For some reason or another, perhaps using more rhetoric, insincere speeches and flawed logic, neither the moon nor the Earth has been damaged by the impact OR the gravitational pull. **What would be the effects in that scenario?** [Answer] Rocks aren't strong enough. Set the moon down and it will crumble under its own weight. The Earth's crust is only a few miles thick and would not take the weight either. You would wind up with a sphere, for the same reason these bodies don't have irregularities on this scale to begin with. Even though it was lowered gently, the collapse of thousand-mile-tall mountains will release enough energy to melt the crust after boiling the oceans dry. [Answer] # The Moon will actually turn into a ring The Earth's Roche Limit for an object with the mass and density of the moon is about 9-18 thousand kilometers away from the center of the Earth. The moon is about 1.7 thousand km in radius. This means that the moon will be subjected to tidal forces sufficient to break it apart as soon as it got to within that distance of the planet. Physically, you cannot have an intact de-orbiting moon "landing" on the planet. [![enter image description here](https://i.stack.imgur.com/ssM71.png)](https://i.stack.imgur.com/ssM71.png) ## Congratulations, your politicians did it! Champagne bottles popping everywhere, right? ## Not so fast, it's getting really tidy in here Of course, the tides caused by a moon that much nearer would be immense (hundreds of meters). Add in the tectonic tidal heating (earth crust movements of several tens of meters each day), and the associated earthquakes and volcanos, and you might get (briefly) angry voters anyway. PS: The magnitude and duration of the tides will depend on how quickly the moon decays in its orbit, and that will dictate if and how it turns into a homogenous ring (no tides). Moreover, the tidal fragmentation is likely to result in chaotic impacts among the fragments, which will likely send significant amounts of material barreling into the Earth, for a bombardment worse than the one that killed the dinosaurs. [Answer] If the moon was gently placed at the north pole after being spun up to earth's rotation a few things would happen. I am not doing the math so my answer will be inexact. I will try to err on the side of survivability. 1) it would look like this [![enter image description here](https://i.stack.imgur.com/56Tok.png)](https://i.stack.imgur.com/56Tok.png) Notice the Moon is quite a bit smaller than the Earth. 2) The barycenter would shift. The moon is 0.012 times the mass of earth so its "down" would effectively be the direction of the just north of the center of the earth. all the dust loose rocks etc on the sides of the moon would fall towards their new home. I assume this will make some noise and make a dust cloud of some size. 3) Under the weight of the moon, the crust of the earth at the pole would be pushed down most likely cracking a bit as the moon tries to reach the center of the earth. Increased magma pressure is probably not a great thing for preventing earthquakes so there may be some of those. We will be lucky of it cracks if the crust somehow just deforms then most of the world's water would drain to the pole. Don't worry we will have some of both. 4) Other than really fun one that happened on moon kisses the earth day we will no longer have effective tides leading to widespread extinction in the ecologies that require them. Well, the ones that did not go extinct from the dust, earthquakes, lava flows and tidal waves. 5) Eventually, the moon becomes a sort of polar mountain and, in the long run, the poles are flattened again, The dominant species is procaryotic. Except the moon is denser than the earth's magma and would sink like a stone. [Answer] There are no long-term effects, because the very short-term effects destroy all life on Earth. The Moon immediately breaks up due to the tidal force from the Earth's gravity, and while some of the fragments eventually form a ring around the Earth, and a few are ejected into higher orbits or out of the Earth's gravitational influence altogether, most of them end up crashing onto the Earth in a colossal meteorite bombardment that melts the surface and sterilises the planet. ]
[Question] [ Considering all the recent articles about humans becoming immortal in the coming 40-50 years, is it really possible? The suggested method is to transfer humans consciousness from their biological bodies to some sort of machine/software. But since we still are miles away from understanding the complexity of the human mind, many (including me) doubt this will be possible in the next hundred or so years, assuming the race and Earth survives that long to begin with. Another, yet harder method would be to reconstruct our biological structure. Make our bodies reconstruct broken cells and develop a quirk in order to duck decay. I'm no where near understanding the biological laws of humans but I would assume this would be a harder task to achieve than the first method described? So what's your viewpoint? Which method could we actually apply and succeed with in a near future? Or does it seem highly impossible to achieve immortality at all? [Answer] I don't think we could, but for philosophic reasons, rather than technical ones. For something to be declared "immortal," is a high claim. But how do you decide if something is immortal? There is a famous thought experiment called the Ship of Theseus, from ancient Greek times. The Ship of Theseus, in the story, is a famous warship responsible for countless victories. However, over the years, she's needed repairs. Replacement ribs, replacement rudders, etc. Eventually there isn't a single piece remaining that has seen one of her famous victories. Is she still the Ship of Theseus? If not, when did she cease to be? One would need to pick a stance about what it means for a "person" to be alive before one could dare talk about immortality. Honestly, the Ship of Theseus is still used today, because there is no consensus as to the answer. Strange phrases like "endurable" and "perdurable," that you rarely see in every day life, crop up trying to explain this dilemma. Literally speaking, what might be immortal to one, thanks to massive replacement of hardware may be dead to another. The other issue is entropy. Lots of people translate "immortal" as "living a lot longer than they can think about." However, this can become *very* difficult as you get onto longer scales. Stephen Baxter's book, *Manifold Time*, explores these longer time scales. Sure, everything could be pretty peachy for a while, but what about when the sun goes out? On a cosmic scale, that's actually going to happen pretty soon (only about 4 billion years away). If your plan is to escape to other stars, what happens when they all go out? Surprisingly, there's a lot more life left in the universe after the stars go out. What about proton decay? Immortality is tough when the particles we think of as defining existence start to wink out. These issues make defining "immortal" remarkably difficult. Thus, you won't find just one answer to your problem. Consider how many religions declare us to already be immortal in one way or another. Buddhism has their system of rebirth. Christianity has their eternal soul. Daoism says we've always been part of the immortal, yet ephemeral. Maybe we already have our immortality, we're just looking in the wrong place. [Answer] There are different forms of immortality. 1. Biological immortality. The most commonly understood form of immortality means that the physical body of a living organism never decays to a point where it stops functioning as a whole and the organism dies. There are at least 2 variants to this: a) Freeze a body to stop all biological/chemical activity that leads to its decay, then un-freeze that body and, if necessary, kickstart its activity. Real examples of this have been observed in a [virus](http://www.nature.com/news/giant-virus-resurrected-from-30-000-year-old-ice-1.14801) and [bacteria](https://www.newscientist.com/article/dn12433-eight-million-year-old-bug-is-alive-and-growing/) that have been frozen. For single-cell organisms, this problem has been pretty much solved, as demonstrated by sperm and egg banks. For multi-cellular organisms, this problem is as yet unsolved, but it should, in principle, be possible. Of course, without further measures, the ageing process would continue as normal after revival, so it's debatable whether or not this would represent immortality. b) Cell damage due to replication will eventually cause more and more cells to fail or slow their functions, until the organism as a whole dies. Identifying and repairing that damage with biological machinery is already something that all multi-celled organisms do, so replacing or supporting the biological machinery with an artificial one is certainly possible. As science and technology advance, the harmful effects of ageing, disease, and (not instantly lethal) injury could be slowed and reversed ever further, resulting in an effectively unlimited natural lifespan. 2. Immortality of the consciousness: Preservation of a person's intelligence, personality traits, memories, etc. through technical means. That can mean a) removing a person's brain and keeping it alive and connected to the outside world in a vat; this has at least an overlap with biological immortality and also requires an advanced brain-machine interface. b) Uploading all those desired properties into a computer system of some sort, making it possible to get rid of all biological parts of the human. Immortality in that case would mean making backups of that information and preserving them in case of hardware failure/obsolescence. Both of these approaches have at least an overlap with biological immortality. This would essentially require creating an artificial intelligence that is indistinguishable from the original person because of its memories and personality. **Either approach would require significant advances in science and technology, but as long as they don't violate any laws of physics, then in principle they are possible.** Which of them happens first, or whether any will happen at all, is anyone's guess. [Answer] Death is what happens when the systems are breaking down faster than they can get repaired. There seem to be two main ways to deal with this. They are not mutually exclusive. Repair systems faster or slow the rate of damage. True immortality would require either infinite speed of repair or zero rate of damage. Neither seem physically possible whether remaining in the original substrate or migrating to one that is more resistant to damage. That said, a distributed mind (say a member of a hive mind) would have to have all instances destroyed simultaneously to end up truly dead. The more pervasive and diversely located the less likely that could happen. A global extinction event on earth would not harm a hive mind that had colonies throughout the solar system. [Answer] I doubt it, while we are growing our knowledge and technical base quickly, there is so much we simply don't understand. Transferring a human consciousness to an AI sounds great, until you realize we don't even know what consciousness **is**, can't read it and have nothing to 'transfer' it to. For a sanity check, it's worth noting that a lot of our advanced medical/biological tools (e.g. vaccines, antibiotics, GM) aren't things we devised ourselves, but as I understand it natural processes we simply observed and harnessed. As such unless there's a natural process to transfer consciousness.... [Answer] **Not in the near future !** What is immortality ? It's impossible. It means to never cease to live. Considering the universe itself will end someday, then all livings will die with it. So nothing could ever be immortal. (without travelling/looping in time ?) **Could be transfer our 'consciousness' in another physical corpse ?** This may be possible. We don't really know yet (well, I don't). While neuroscientists seem to progress in this way we are not yet close to doing it. It is already possible to plug some neural implant to [control animals](https://en.wikipedia.org/wiki/Remote_control_animal). And this has been done [for human to control computers](https://en.wikipedia.org/wiki/Brain%E2%80%93computer_interface) too. **Could we artificially evolve our body to live longer ?** We did it, we do it. We've been able to create an [artificial heart](https://en.wikipedia.org/wiki/Artificial_heart) so far. Organ transplantations are better and better (and research about clonage just at their beginning). While Medicine still makes progress, I bet we'll live longer in a hundred years than now. Though some studies say that we live longer because of social things (such as retirement, paid leaves, etc.). While it's hard to repair our biological body, it may become easier with artificial organs in the future. Still, DNA research may help design some micro-organisms able to interact and repair our biological body. **Conclusion** Immortality (IMO) will never be reached. It's not impossible that we could expand our lifespan to the point where we live several hundred years but not in a near future. The impacts of such a thing on demographics would be very huge. Our capacity to biologically procreate would certainly stay the same though (limited number of [ovocytes](https://en.wikipedia.org/wiki/Oocyte)). Plus, I strongly suggest reading A. E. van Vogt novels : [The world of null-A](https://en.wikipedia.org/wiki/The_World_of_Null-A) which kind of aboard the subject of immortality with (IMO) a real consistence and questions ask ! **The philosophical part** **Is it still Human ?** We (Human) are essentially composed of a body and a mind. Some think they are two separated things, but I think they are in fact inseparable. Our body is able to perceive the outside world and thus our mind interpret these perceptions and learn from it. If a human brain was to be uploaded in a computer, it would certainly loose its perceptions to acquire some new others. Could we still call this entity a Human ? I seriously doubt it as it would have no biological/physical needs and its behaviours would then be affected by this lack of needs. **Is it really unique ?** When it will be possible (if ever) to upload someone's consciousness into an artificial body this would cause some tremendous difficulties for mankind to define identity. What if the same brain is uploaded twice in different bodies ? What if we lose some minds but then we remind we have some back-up ? Which one is the "real" mind of the person ? This kind of questions will arise and will be difficult to answer. [Answer] # Facts First, there was [the ear](https://en.wikipedia.org/wiki/Vacanti_mouse) on the back of a mouse. Then, there was the [trachea](http://www.technologyreview.com/news/522576/manufacturing-organs/) grown from the patient's own stem cells. Closer to the bleeding edge are grown [livers](http://americablog.com/2014/03/science-regrowing-human-organs.html) and lungs. Today, we have 3D printers which can print biological tissue the way you would print a picture off your computer! Also, hydras, some jellyfish, and planariums may already be [immortal](https://en.wikipedia.org/wiki/Biological_immortality#Hydra)! # Speculation We have every reason to believe that the exponential growth in biotechnology and nanotechnology will continue for the foreseeable future. At what point that will enable human immortality, nobody can say. But there is also no intrinsic reason that living creatures have to die. Rather, death appears to be designed and programmed into them to facilitate generational adaptation (raising the question of whether immortality is actually A Good Thing(TM)). If humans do become immortal, it will almost certainly start out with organ replacement, proceed to in situ tissue regeneration, and conclude with complete disease management/eradication. Whether humans also achieve the ability to upload consciousness is orthogonal to biological immortality. [Answer] My answer considers biological immortality only. I *feel* our understanding of the brain, consciousness, etc. is too limited to consider uploading consciousness or transferring it into another biological entity as means for achieving immortality in the near future. ## Biological Immortality [I've read several articles that state human life expectancy may begin growing at an increasing pace.](http://www.independent.co.uk/life-style/health-and-families/features/big-think-is-the-human-life-span-accelerating-faster-than-people-age-1805536.html) It's possible that if life expectancy begins increasing faster than people age, there will arise a generation which could hope for immortality. Whether immortality could be achieved would depend upon both civilization being maintained and advances in medicine continuing at pace greater than the population ages. The term "immortality" would apply to the generation as a whole. Unlucky individuals would still die from disease, accident, genetic defects, etc. I suspect some longevity treatments would benefit everyone regardless of age, while other treatments might need to be applied at or before a certain age. Meaning people passed the age would miss out on the longevity treatment and continue to age or decline. I suspect that the limiting factor wouldn't be chronological age so much as the biological age (hormone levels, amount of cellular damage, disease processes, etc.). It might be odd to live in such a society. Where someone a few years younger than you stops aging while you continue to age. Imagine being visited in an elder care home - you at the ripe & decrepit age of 100 while your sibling 2 years younger appeared to be someone in their 20s or 30s. Some people would become extremely bitter about missing out. There would also be the societal strain of rapidly increasing population (people not dying but continuing to reproduce). Treatments to greatly increase our life expectancy might require laws that impose reproductive constraints. Some people might voluntarily forgo the treatments in order to not be reproductively constrained. ]
[Question] [ In this question: [How far can a time traveller go into the past before his electrical equipment becomes unchargeable?](https://worldbuilding.stackexchange.com/questions/6827/how-far-can-a-time-traveller-go-into-the-past-before-his-electrical-equipment-be?rq=1) @Mark assures us that "Building a generator can be done at any time:" (just wind copper). According to an eHow article, after obtaining an engine (we'd use a windmill, waterwheel, bicycle/animal motive power, or some other type of engine; simple exercises left to the reader), you need: > > "2: Choose an AC generator head. This head will use an internal magnet to create electricity when the shaft mounted magnet is spun by the external engine." > > > "3:" (Alternator) > > > And on [another site](http://www.otherpower.com/pmg2.html), a guy created an wooden (armature) alternator (which contrary to @Youstay-Igo's assertation, does not seem to need that much precision), but the components?: > > * "18 surplus NdFeB rare earth magnets" > * (and epoxy, and nice wire) > > > These magnets are not easy to come by because rare-earths are... well, *rare*. (and I'm assuming higher-power magnets are what makes this alternator as effective as it is, versus say, lower power magnets). From the original question, one of the comments is: > > @AdamDavis: Building a generator is considerably more difficult than one might assume. Lodestone, naturally occurring magnetic rock, is not only rare, but fairly weak. Generating 5W out of a motor built out of lodestone and crude wire is going to be an exercise in futility. The fabrication of stronger magnets requires electricity, thus a chicken and egg style problem. > > > I understand that non-mass-produced wire in the past (hand-drawn, ouch!) is a problem. As well as wire coatings, which are at least as problematic (for any type of longer-term use; and/or preventing the melting of your copper wire into a copper lump while under load). But the magnets seem to be the real sticking-point. Obviously, a time-traveler - like in the existing question - caught in such a situation would begin to assess his problems, and could get magnets and wire and/or a solution anytime before going further back than 1880s. And probably some solutions further back than that (Judean batteries, etc). **But, if a time-traveler jumped back pretty far in his first jump, how would he make magnets/wire to make a generator; or, how would he make a generator (without those)?** Granted, that in the past there's plenty of resources, that you don't have to "mine": native copper, deposits that're still on the Earth's surface, etc. Lodestone is more rare however. Assuming he can prospect or talk to people who know where such resources are, we will assume he can get to it (ie: he doesn't have logistics issues (he's eating Shmoo), and can boop around using his (sealed) antigrav flitter to get to any location). He's got some limited amount of power in his laptop/cell/etc, so if he's careful, he could set something up (what would he need to get that power out?) to jump-start his chicken-and-egg problem of creating a strong magnet. Maybe. (ie: how much power do you need to make a magnet, for how long?) *But, how would you do **that** (make a magnet)?* We're leaving the rectification of DC and voltage regulators (capacitors, diodes, etc) and stuff alone. I'm going to assume he has a robust laptop plug that handles a fairly dirty/unregular AC power supply input (ie: about how effective your laptop power cord/block is), as I don't see how he could easily make those, but bonus points if you want to tackle that. --- In case it wasn't clear: Previous question assumed (and I am to), that he wasn't well prepared to do this; he just grabbed a few things and jumped in his time machine. Otherwise, **obviously**, you'd take a solar battery unit/hand-crank generator/@Youstay-Igo recommends a dynamo (and you've got one of those lying next to your briefcase/laptop, don't you? /snark), and a set of tools to make new things and spare parts: rectifier to run off of batteries, magnets, wire, capacitors, diodes, voltage regulators, interfaces, etc. Spare time-machine, etc, etc. ie: What do you have right next to your laptop/cellphone? Probably not any of those things, nor a large-enough, powerful enough, set of magnets (how large is needed?) --- Sounds like we might be using electromagnets (iron with wire wrapt around it) to be our magnets for the first iteration... if there's a way to power it. I'm thinking USB out of the laptop - which avoids the rectification problem. If not, why not power the electromagnets with hand-made chemical batteries; potatoes if nothing else? [Answer] For the record - my entire Navy career was as an electrician, and my degree is in power electronics. Any first year EE student has observed that you really can make a (fairly poor) voltage by simply waving a coil around in the air. This works in the usual way, because the earth has a magnetic field - nothing weird. It is weak - maybe even weaker than you think it is. But, it's enough for what we need. The biggest problem now is that the time traveler absolutely must have a way of rectifying current flow or else fail entirely. The reason why he needs it is because we need to feed the output of the generator into the input of a handwound electromagnet at the core of the generator end through sliprings - literally a round piece of metal that another conductor can ride on, to which the magnet is connected. If the input isn't rectified, then the north and south poles of the magnet switch places every cycle and your alternator doesn't alternate very well. If you can do that, the next problem is controlling the feedback loop. When trying to start the generator, everything is great - you have a tiny little current flow gradually bolstering the field of the ferromagnetic core. Once the field comes up, you have a problem - you are passing a non-zero voltage through a very low resistance. This is will do one of two things - most likely, it will prevent your generator from being able to develop a workable output, because it is shorted. But if you work real hard, and have steady hands, and built a pretty good generator head, the feedback loop will spike the voltage on the generator head and utterly destroy all your work. Note that this isn't free power - the equation sacrifices current flow for voltage and you arc through your insulation. This is almost the exact reason why permanent magnets are used so often - since they are constant, you don't have to have as robust a regulator. I'll skip over some of the more technical stuff by saying that it is much more likely that the brave adventurer would be forced to build a DC machine. This is actually harder to make, but, it allows the use of a special mechanical rectifier called a commutator. The commutator is a multi layered ring of conductive sections separated by a mineral insulator in thin strips, on which a conductor can slip while it is rolling. Each set of sections on opposite sides of each other is connected to a separate conductive loop, and no two sets are connected. Since the current goes into and out of the commutator at fixed angles, the corresponding magnets can be placed at a certain angle with respect to the commutator entry and exit conductors - the rotor spins but the relationship between the magnetic fields doesn't reverse. (Yes, this is about as non-technical as I can make this - sorry guys.) This still didn't solve our regulator issue, but if your time traveller knows how everything above works, there's a reasonable chance that he knows what a magnetic amplifier is, and that it's way easier than building a vacuum tube from scratch. This is basically a fancy transformer, designed intentionally to saturate at a specific point and then have a much reduced response. Without getting too into it, if he can do the math, and has copper and an insulator, he can do this and the electromagnet should self start AND not burn up. So, thousands of hours of grueling material round up, refinement and tool manufacture later, if he didn't starve to death or have a surprise party with some velociraptors, he now has what is actually probably a fairly decent generator head. The engine should only take about ten times as long. Build a bicycle, maybe. Edit: I assume this took a downvote because the question tries to avoid the rectification issue. For clarification, in the case where permanent magnets aren't available, *avoiding rectification is not an option*. A permanent magnet keeps the same polarity as it goes around the armature, but if you attempt that with the raw, unrectified output of a handmade generator, the polarity of the electromagnet flips as it makes it's way around and you get no output. [Answer] ## Overview **A:** Very hard! But not impossible... You can use a magnet to make electricity, and you can use electricity to make a magnet, but you always need one to make the other! Obviously, an electromagnet is out of the question, since electricity is the resource you are trying to obtain. And we agreed that naturally occurring magnets are very difficult to come by. So you are left trying to create a permanent magnet from scratch. ## Process If you have basic metallurgy available, you can heat an iron rod and expose it to a magnetic field. You might as well use earth's magnetic field, since it's "free", but it also helps if you have any other magnet at all, including a weak lodestone (or any magnets in your laptop! like the one in Mac power plugs ;). With sufficient practice, it should be possible to make stronger magnet than you started with (the heat frees the magnetic domains to be re-oriented, and any induced magnetic field will orient them in the same direction, statistically speaking). You can also use impact force from a hammer to free the domains, but this is probably much less effective than direct heating. Cool the heated rod, and the new domains will be "frozen" in place. You now have a new permanent magnet. Get another rod, do the same thing, but now use your more powerful newly created magnet to induce a stronger magnetic field in the new rod, and you should be able to make a magnet as powerful as this technology allows. The limit would be how many magnetic domains you can liberate in the heating process, and how many you can orient using the induced magnetic field. The more magnets you have, the stronger a field you can induce in any newly created magnet. ## Conclusion Even with no permanent magnet at all, you can still create one with just iron and a fire hot enough to liberate the magnetic domains within. This is because we live on top of a giant dynamo which conveniently provides a life-saving magnetic field. Without it, you would be reduced to bootstrapping the process with an electromagnet, which might be possible using static electricity, but would surely be very painfully tedious to construct. [Answer] A simple generator is relatively easy to build. <https://www.wikihow.com/Make-a-Simple-Electric-Generator> The lower the voltage output, the easier it could be made. The very first generator, the Faraday disc generator, was created 1831 (by Michael Faraday) using motion similar to that of a spinning-wheel and even used some of the generated current to power the magnet. [![Faraday disc generator](https://i.stack.imgur.com/hasIL.jpg)](https://i.stack.imgur.com/hasIL.jpg) The simplicity made it inefficient, but it was enough to engage a young Nikola Tesla, who worked on it's design before developing a much more capable, drum-based generator. In order to start generating power, you'd either need fairly strong magnets (which would be impossible to locate), or enough electricity to initially power an electromagnet. Interestingly enough, it could easily be possible to extract enough DC current from lightly boiled potatoes, in order to get things started. <https://www.smithsonianmag.com/innovation/a-potato-battery-can-light-up-a-room-for-over-a-month-180948260/> So, as long as your traveler landed in a time period where tooling and copper craftsmen were common, then It might be possible. The early Egyptians were one of the youngest civilizations known to make copper jewelry, so that would probably be the earliest, plausible time period. The real question is ... What need would there be for crafting an inefficient generator, when simply using potatoes could potentially be more efficient? [![Potato batteries](https://i.stack.imgur.com/M2rFh.jpg)](https://i.stack.imgur.com/M2rFh.jpg) [Answer] You can build as generator as long as you can get or make insulated metal wire (preferably copper), so as you might imagine, you can go pretty far back! The problem, however, is, that generators produce AC power, while devices such as your cellphone require DC power. AC-DC transformers require at the very least capacitors and diodes (and voltage regulators if you want a stable voltage). I guess you could make capacitors and diodes if you had the required knowledge, but I suspect they'd be unreliable, inefficient and bulky. You'd be better off taking the parts from technology you brought along. A cellphone charger, for example, contains an AC-DC transformer (apart from the AC-AC step down transformer). [Answer] Real high power generators don't use *just* magnets. The really powerful ones (like the ones at power stations) actually use electromagnets instead, because its much easier to get a strong magnetic field out of an electromagnet than to get enough rare earth magnets to do the trick. Of course, this is a chicken and egg moment. The real generators actually do have smaller magnets in them, which can generate just enough current to bootstrap the more powerful electromagnets into operation. From then on, the magnets do help a little, but most of the magnetic field is generated by the electromagnets. [Answer] It is possible to build the generator if it is possible to make the somewhat insulated wire of any kind, and is possible to make its mechanical part (rotating rotor). A magnetic field is required around the rotor. We could use electromagnets for it, but at least small permanent magnets would make the generator easier (or even just possible) to start. The generator does not need the rectifier because a simple mechanical rectifier can be mounted directly on the axis of the generator. Finally, to get rid of pulsations, it should be possible to build more than one generator and connect them in parallel. The averaged output should be smoother. [Answer] If you are time-travelling into the past and want a power source to charge your apparatus, simply bring a dynamo with you (half a dozen for precaution sake). You can rotate its head and it will give you a steady flow of dc electricity at the terminals. Don't get into the mess of ac generator building in the past. It is going to prove extremely difficult, if not plain impossible. Crude tech would be available with metallurgy and all, but the precision of parts required for a reliable ac generator is something you can hardly ever expect to build. ]
[Question] [ In my fantasy world, I have a large swamp. It's about 20 miles long, by roughly 10-15 miles wide. Here's my question. What circumstances (weather, climate, fauna, wind, etc.) would I need to create this swamp? In other words, how can I make its existence credible to those who know science? Please let me know if you need more details. EDIT: I do not have any particular type of swamp in mind. What I'm after is trees, and basically enough foliage/uncertain footing with the water to make it a maze. Steam or mist would be great too. [Answer] Wetlands come in four main varieties, defined by two questions: is the water fresh or salt? And, is the wetland largely covered with grass and shrubs (a marsh) or trees (a true swamp)? [Wikipedia](http://en.wikipedia.org/wiki/Wetland) gives bogs and fens as distinct types, but for most purposes those are just specific types of marsh. A wetland forms when an area gets significant water input and slow water output. The water can of course come from rain, but it can also bubble up from the ground (rain in higher elevations trickles down and emerges from aquifers in the area of the wetland), or flow in from adjacent bodies of water like the sea, a river, or a lake. So those are your ways to *get* water; note that this means you can have a wetland in an otherwise dry-ish area, though that's uncommon. Consider the Nile delta, which gets enormous input of water and silt from the Nile. Then there's output. Most well-watered areas aren't wetlands because of *drainage*. The ground slopes enough, even in generally flat areas, that water gathers in creeks and rivers instead of standing. So most wetlands are very flat, allowing water to stick around instead of quickly flowing away. In warm, dry, and/or windy areas, you'll also have a lot of evaporation, fighting the formation of wetlands. This is why flat dry areas end up as salt flats instead of marshes: water occasionally floods the area, but in a shallow layer it quickly evaporates, leaving salt behind, and there's no chance for lush plants to take root. So most wetlands will be in flat areas with high rain or nearby bodies of water. If it's hot, they'll need a *lot* of rain or *large* bodies of water; if it's cold, you don't need much. Indeed, the boreal forests of Canada and Russia have vast stretches of cold bogland, because although there's relatively little rainfall there's also hardly any evaporation. Any little dip in the ground will fill with meltwater in the spring and stay water-logged until the fall freeze. Similarly, vast swathes of tundra are marshy during the summer thaw. Whether a wetland is salty or fresh depends on where it's getting its water. Seacoasts will have salt marshes (e.g., the U.S. mid-Atlantic coast) or saltwater swamps (e.g., the mangrove swamps of Florida). I suppose you could have a salt marsh inland, if its water came through large salt deposits, but if so it may not have much life since there'd be no way for saltwater plants or animals to migrate to it. Strange life forms would eventually adapt to life there, like the thermophiles of Old Faithful. The marsh vs swamp axis is a little tougher. Basically, an area will grow trees if there's sufficient precipitation relative to evaporation. The magic number is about 50 cm per year in the subarctic, 75 cm in the temperate zone, and 100 cm in the tropics. A little less than that and you get shrub or scattered trees near rivers (prairie, savannah), a little more and you get open woodland - or, for your purposes, you get a swamp instead of a marsh. There are additional factors (soil depth, soil fertility, grazing from large animals), but the main one is rainfall. If you want a marsh in a rainy area, you can declare the soil is too exhausted and the migrating muck-beasts eat any saplings. If you want a swamp in a relatively dry area, you can declare the soil to be richly endowed, and the trees to be very hardy and slow-growing, able to cope with dry spells. A few more notes: * Wetlands can be seasonal or year-round. * They're a pain to traverse, since if you try to walk you'll hit thick mud or deep pools and if you try to boat you'll hit thick mats or sandbars. * They can be drained even with medieval technology, and usually will be when mankind encroaches as they're not suitable for growing crops. * They are usually teeming with plant and animal life, because of the omnipresent water, but they needn't be: without an inflow of fresh nutrients a wetland can be a tough place to get nutrients. Such wetlands are like tropical rain forests: they have vast amounts of vegetation which accumulated very slowly, and if cleared will not be good for agriculture without massive fertilization of the soil. * The growth of vegetation combined with the lack of oxygen to support decay means wetlands can accumulate large amounts of carbon. This starts out as [peat](http://en.wikipedia.org/wiki/Peat) and eventually becomes coal. * This may be surprising: for pre-industrial societies, marshes were a key source of iron ore! Rainfall in iron-rich uplands would flow down to wetlands and accumulate, aided by bacteria, into lumps of hematite. In England and Wales, people would poke through the moors periodically looking for these deposits and take them to the blacksmith for refining. [Answer] The dominating factor for the formation of a swamp is terrain. Swamps tend to form along rivers or coastlines and have minimal elevation variation. They are characterized by water-saturated ground during the growing season and standing or slow-moving water the rest of the time. Swamps can be saltwater, fresh water, or a brackish in-between. The varying water levels are conducive to certain forms of life, such as alligators, ducks, clams, and snakes, which have all evolved means of coping. Swamps are also a good place for trees, and can support a variety of different species, such as cypress and mangrove. The [National Geographic](http://education.nationalgeographic.com/education/encyclopedia/swamp/?ar_a=1) and [US EPA](http://water.epa.gov/type/wetlands/swamp.cfm) websites have good information on swamps. [Answer] I don't think that 20x15 miles swamp is any massive. Check out [Vasjugan Swamp](http://en.wikipedia.org/wiki/Vasyugan_Swamp) for example. To answer your question, there are too many possible ways for a swamp to form. Vasjugan, Everglades, Polessky Swamps, etc all have different genesis and conditions. [Answer] Find a low-lying forest, where the ground is relatively flat, and the water-table is close to the surface. Make sure it has poor drainage. Now, commence logging operations. Cut down the entire forest. One man-made swamp at your disposal! The important thing to note here is that [swamps are characterised by stagnant(still, or slowly moving) waters](http://en.wikipedia.org/wiki/Swamp#Geomorphology_and_hydrology). Many swamps and wetlands have loads of vegetation in them. These usually are plants that *love* wet environments. Mangroves and [Alders](http://en.wikipedia.org/wiki/Alnus_glutinosa) are good examples of swamp-loving trees. ]
[Question] [ I'm building a world with medieval-era technology, in which there is a basic type of magic, where magic users can, rather than just waving their hands and doing anything they please, can instead control physical energies (like kinetic, heat, electrical, chemical etc.). In this world, a lot of potential energy can be stored in a reasonably small object (I won't go into numbers, for the sake of the question let's just say "a sufficiently large amount") that can essentially be a battery to power magic if one can control it. Then I realized, it could also possibly be used to power machinery... like robots. Now, assuming the robots can be programmed to control how to use this energy for things like movement etc. a simple constructed body (humanoid looking stone/wood/metal construct built with hinges instead of joints for example) would be able to be powered for a limited amount of time. Then, if the "battery" is replaced it can go on indefinitely as long as the body is properly maintained. As the robots can manipulate the stored energy in their "batteries" for their own operating power, let's assume that they get their sensory inputs by detecting energy from light/sound etc. so that they can see and hear things. However, it is the programming that I am struggling to find a reasonable explanation for. The closest thing I can think of from other fantasy worlds that operate without modern technology and programming techniques are steampunk-type robots, but I'm not sure if they are just given commands via hand-waving magic. Is there any way to give commands to this type of robot without using hand-waving magic? Or could there be something that would act as a reasonable substitute for the internal machinery of a robot allowing it to "think"? I did think of stuffing the brain of a human/animal inside the robot and having the energy from the battery power it, but if there is a less grotesque solution that would be much better. --- As an explanation for why a world with this magic is still medieval era tech, let's assume that the monarchy controls all of the wizarding population, and only allows them to build what the King requires, like an unquestioning robot army that will protect him and his family. --- **EDIT:** I've just realized that I entirely forgot to mention that the robots don't need to nearly be as sophisticated as humans. It was pointed out that I'm essentially describing a Golem, but I'm hoping for a creation with a little more ability for free thought and reasoning, like to recognize friend from foe/ intruder from guest rather than the more literal commands of attack anything that approaches. Also, if you can find a way to use this magic to advance the tech a little to a point that you might need for this creation, that is reasonable (you do have an army of wizards at your disposal after all). [Answer] > > Is there any way to give commands to this type of robot without using hand-waving magic? > > > Realistically, no. You've probably seen videos of computers or robots that have some capacity to interpret what people say. What they don't tell you is how much raw data is required to build the data model that allows the computers and robots to do that. For interpreting text (that's already in a nice easy-for-a-computer-to-use format) you'd want to have a dataset of thousands of texts. These aren't "See Spot Run" texts, these should be on average short novels. You'd need a very large group of people dedicated to transcribing data to produce a dataset that could begin to be used to teach these robots how to understand you. Even with a dataset large enough, medieval technology would still fail at this - the math and physics known to them are not sufficient. The algorithms for interpreting text (let alone understanding spoken language) require quite a bit of math that would be well beyond the reach of a medieval wizard. To make it even worse, you don't just have to teach the computer how to understand the words that are spoken, *you have to teach it how to hear*. That requires a knowledge of how sound works and the types of sound waves that speech produces. Even with an army of wizards at your disposal, I don't think you'd be able to overcome these problems. Each step of advancing knowledge of physics, math, and algorithms takes a lot of time because of how many possible dead ends there are (with some dead ends not being apparent for quite a while). **Given that we're not going to be able to do this without hand-waving**, why not introduce handwavium crystals? These crystals resonate with magic, and under certain circumstances (perhaps magic used directly on them in a particular way) they can reproduce a series of magics used in their presence. Once placed inside the robots, they would work like an artificial brain - a wizard would use magic to direct the robot's body to do a certain task. Then the crystal is activated using the battery and will reproduce the same actions. A new robot would be very dumb - it could only exactly mimic the actions that the wizard just caused it to do. Over time, the crystal would learn more subtlety and be able to handle situations with more versatility. This makes older robots (or at least their crystals) much more valuable. [Answer] Summon and bind an entity into the machine that's under a geis to follow instructions. It's the occult equivalent of AI. Your magic user simply tells it what to do, and/or can use wards and runes to program it. The Summoned Entity has to obey. Like any heavy machinery you have to treat it with caution. **Edit:** Depending on what kind of entity your magic user summons you could have varying levels of intelligence. A SE with low level intelligence would be able to handle basic instructions ("Robot, fetch water", "Robot, sweep floor"), but you wouldn't want to trust it with complicated or creative tasks ("Robot, assemble IKEA bookshelf"). A SE with high intelligence would be able to handle greater responsibility and think outside of the box, but you'd potentially have to be more careful programming in safeguards to prevent rebellion, the magic equivalent of Sky-Net. Otherwise, you could design a magic logic circuit using runes, glyphs, gems, metals, whatever. You could program it using the magic equivalent of punch cards, but I see it being very limited. At least at first. Possibly good for simple/repetitive tasks. [Answer] Computation is ubiquitous. Programming will be a natural thing to do if basic building blocks for computation is easily available as in your world. Look into [finite state machines](http://en.wikipedia.org/wiki/Finite-state_machine) to get an idea of how computers could work mechanically. [Answer] I feel your objection to using a "golem" may be rooted in the standard D&D monster. The traditional Golem from some Jewish lore has a trait that may be exactly what you are looking for. A *shem* is created by writing various Hebrew runes on a paper, forming one of the Names of God. This was placed in the forehead or the mouth of the Golem, which activated it. In recent fiction (Feet of Clay, a Terry Pratchett disworld novel), a Golem was created with a rather long document placed in it, giving it direction. This can easily be used to fit your need. The programming for your magic robot is written on a similar document, which is placed within the robot. The specificity required for this programming is entirely up to the amount your story needs. [Answer] Given the low technology and the type of magic, the robots will become more of an external extension of the user. By manipulating water flow (since they will not understand circuits) robots will be hydraulic machines that do hard labor that they might not be strong enough to do. [Answer] I'm not sure why you deride putting the spirit/brain of an animal into the robot as "handwavium". Given the limits of a magical world's tech, that would be the best way to do it! Whatever spirit motivates a dog, or bear, "knows" how to run a body already, so magically attaching it so that those same thoughts activate the golem's equivalent parts correctly would be as straightforward as magically making an articulated physical body the same way. You might need a different, specialist magician to bind it for you, perhaps. [Answer] I have also magic robots in my world. I faced the same issue as you and this is how I solved it. I call it an animatrix. It is a sort of artificial intelligence/ soul made with magic and bound to an object. In most cases this is a cube. When activated an animatrix will light up and project itself over the object it is bound to. The reason these objects are mostly cubes is because they fit well into other machinery and the projection of an animatrix is a cube of sorts as well. The projection starts off with a cube made up from a bunch of smaller cubes. Each cube has a purpose and can be 'opened', meaning the animatrix will project that cube instead of the whole. This cube can exist of smaller cubes and so on. The animatrix is generally controlled by though, but this needs an interface though (something to put your hands on in general). The real 'programming' is found within the logical cubes and the spell circles that make animatrices. They can be used for multiple purposes. locking a gate (picklocking these gates looks a bit like hacking then), managing machinery, robots, ... . I hope this was helpful to you. ]
[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/9277/edit). Closed 8 years ago. [Improve this question](/posts/9277/edit) In a story I am making, I want the main character to face the largest government organisation. To make them seem more intimidating, I need the biggest ship possible. So, what would be the maximum space ship size, with it being structurally stable? Tech available would be around the time before (but not of) FTL drives. They can go near the speed of light, but not faster yet. Also, no "Ancients" involved in this one (except for maybe power source, if it is needed to power the giant). [Answer] ## That's No Moon, That's a Space Station Ship! The first fundamental limitation to a space vessel's size is material strength. Beyond a certain point, whatever material your ship is made of will collapse under its own weight without exotic active materials. We can do some estimates using the [Lane-Emden equation](http://en.wikipedia.org/wiki/Lane%E2%80%93Emden_equation) to predict the stresses the spacecraft will have to endure. I assume a spherical, incompressible ($n=0$) spacecraft in a vacuum. The math is a bit complex but the results are simple. Given a density $\rho$ and a maximum stress $\sigma$ the maximum size of the spacecraft is: $$ M=\sqrt{\frac{6\sigma^3}{\pi G^3\rho^4}} \\ R=\sqrt{\frac{3\sigma}{2\pi G\rho^2}} $$ Let's try three different materials: * 4142 carbon alloy steel: $\rho=7900~\text{kg}/\text{m}^3,\ \sigma=85~\text{ksi}$ * 6061 aluminium alloy: $\rho=2700~\text{kg}/\text{m}^3,\ \sigma=35~\text{ksi}$ * Grade 5 titanium: $\rho=4400~\text{kg}/\text{m}^3,\ \sigma=155~\text{ksi}$ Only a portion of the spacecraft will consist of structure, let's say $5\%$ of the total volume. We will multiply both the density and the yield strength by this fraction. * Steel: $M=0.035~\text{M}\_\text{Moon},\ R=0.67~\text{R}\_\text{Moon}$ * Aluminium: $M=0.079~\text{M}\_\text{Moon},\ R=1.3~\text{R}\_\text{Moon}$ * Titanium: $M=0.28~\text{M}\_\text{Moon},\ R=1.6~\text{R}\_\text{Moon}$ We can see that from a mechanical standpoint a spaceship can be almost unimaginably huge, comparable to the size of the Moon (although much less dense). The gravity inside the spacecraft increases proportionally to the distance from the center, reaching a maximum at the surface of: $$ g=\frac{GM}{R^2}=\sqrt{\frac{8\pi G\sigma}{3}} $$ For our test spacecraft the surface gravities are on $0.013~g$, $0.008~g$, and $0.018~g$, so you'll still be pretty much floating on the inside. ## I Feel the Need... the Need for Speed! The second limitation is power. If a moon-size spacecraft is insulated well enough that its surface is a frosty $-200~^\circ C$, then the power requirement to maintain the internal temperature due to heat loss is about $60~\text{TW}$, or about four times global energy consumption. However, this pales in comparison to the energy needed to move around the solar system. Moving a tenth-moon-mass spacecraft from Earth orbit to Mars orbit will require at least $2\times 10^{30}~\text{J}$ of energy (the Sun's entire energy output for two hours). Even assuming $99\%$ efficiency, that the energy is slowly applied over a year, and radiators cover the entire surface of the spacecraft, you'd need to maintain a temperature of $4200~\text{K}$ to reject the waste heat. Doing the math (again, too complicated to waste space here) we find that the maximum size for a spacecraft radiating at a given temperature and power is: $$ M=\frac{36\pi\sigma^3 T^{12}}{D^3\rho^2}\\ R=\frac{3\sigma T^4}{D\rho} $$ Where $\sigma$ is now the Stefan-Boltzmann constant, not stress, and $D$ is the waste power generated per unit mass. In our case (a year-long trip to Mars using a $99\%$-efficient reactionless drive) $D\approx 0.1~\text{W}/\text{kg}$ and $\rho\approx 200~\text{kg}/\text{m}^3$. Assuming we maintain a comfortable exterior temperature of $300~\text{K}$, this gives us: $$ M=270\,000~\text{t} \\ R=70~\text{m}=230~\text{ft} $$ This is actually a *minimum* estimate of the maximum size, since a sphere is the least-efficiently radiating shape. You can get much larger by extending radiative surfaces out from your craft. As a rule of thumb, at the energy density mentioned above you need one square meter of radiator for every five tonnes of spacecraft, or one square foot for every half-ton. (Remember if you have "wings" that radiate on both sides the area is doubled!) So while a spacecraft could structurally be the size of a small moon, the energy requirements would make it impossible to manage. You should be much safer with a ship in the million- to billion-tonne range, with a size from a few hundred meters to a few kilometers: think [battlestar](http://en.battlestarwiki.org/wiki/Galactica_(TRS)) size. [Answer] There is no upper limit other than those given by the propulsion technology available and the ability of your dockyards to build. Size would have effects on the geometry and design of the ship. The reason for this that without gravity, atmosphere or other external factors there are no real forces other than the thrust of the engines the spaceship needs to be rigid against. And those forces are part of the design, so it would be a question of what compromises are you willing to make, not an absolute upper limit. So your technology might put a limit on mass per engine before you start experiencing structural issues. So you increase the number of engines, which makes your ship "flatter" and has effects on manoeuvrability... and so on. Even tidal effects on orbit, which might be significant for a large ship, would be simply design parameters. Probably they'd simply give up on orbital manoeuvres? Closest thing to an absolute limit I can think of is that a massive enough ship would have a non-trivial gravity field of its own. This is not a problem by itself since you could build the ship to be in hydrostatic equilibrium. But if the ship uses a propellant based propulsion, significant part of that mass would be transient. At that point I think people would just build more ships instead of bigger ones. Also, given the presumed difficulties of radiating heat in space, a very large ship would probably have very large area for its mass. So the construction might be something like a bubble. Discrete modules kept together by cables, connected by flexible tubes and pushed apart by pneumatics. A structure like that could be very large. The modular construction would make it reasonably simple to build in any size as well. I think that there probably is some specific technology you want to use that imposes a much stricter size limit, though. ]
[Question] [ This is the second question in my *Arctic Airships* series of questions. The first one is [Arctic Airships, Part 1 - Generating Electricity](https://worldbuilding.stackexchange.com/questions/8635/arctic-airships-part-1-generating-electricity). The setting is outlined in Part 1, but I'll rehash the premise here. **The premise:** An Earth-like planet plunged into an ice age roughly 2,000 years prior to the story. The ice sheets extend to a latitude of about 50 degrees above and below the equator, though I this story (so far) takes place in the planet's Northern Hemisphere. At a latitude of about 67 degrees north are a series of ten or so small villages, each with a population of 500 people. The technology is roughly that of the late Victorian era - so no automobiles. In fact, there is no clear boundary between icy land and frozen-over water, and it would be extremely dangerous to travel overland in any way. Submarines have not been developed, nor have airplanes; a lack of fossil fuels means that internal combustion engines are nonexistent. **The problem:** Some of our heroes have gone rogue in an airship to see what lies beyond the Rocky-Mountains-esque mountain range to the south of their land. To their surprise, there is nothing but more ice as far as the eye can see. Yet they are brave, and they are determined to carry on, risking life and limb to go where nobody has gone before and returned to tell the tale. The problem is, they forgot to bring a compass - or, rather, the engineer dropped it shortly after takeoff. They have nothing that they can use to create a new one. The crew decides to use the Sun for navigation; unfortunately, they're in the middle of winter, where the days are extremely short, if existent at all. It seems like they won't be able to find their way. They *could* just go straight, and that is in fact their plan, but a storm hits, and they lose their bearings. How can they figure out which direction they are going? They have only the supplies on board a typical airship - maintenance tools for the engines (e.g. wrenches, screwdrivers, drills, etc.), food, paper and pencils, some clean clothes and sheets, and various personal items. --- I should add that I'd like to avoid extended discussion; please use general chat or [a separate chat room](http://chat.stackexchange.com/rooms/20221/discussion-on-question-by-hde-226868-arctic-airships-part-1-generating-electr) created for Part 1. [Answer] You don't really specify what equipment they've got, so I will assume equipment such as would be found on a long-distance airship or sailing ship on Earth in 1900. In particular, they would have a [sextant](https://en.wikipedia.org/wiki/Sextant), a [marine chronometer](https://en.wikipedia.org/wiki/Marine_chronometer), and a [navigational almanac](https://en.wikipedia.org/wiki/Nautical_almanac), in addition to the now-lost compass, and are familiar with the constellations. In such a situation, finding north is trivial: there's either a North Star that anyone should be familiar with, or the almanac will list a near-north constellation and the calculations for finding north from it, or the almanac will have a procedure for finding latitude from a bright star that implicitly involves finding north (on day X, at solar time Y, star Z will be at its maximum elevation in the south). Once you've established north, maintaining a constant south bearing is easy, even without a compass: pick two distant south-pointing landmarks in line, fly towards them, and once you reach the near one, pick a third distant landmark in line with the second. Repeat. Periodically re-find north to correct for navigational errors. [Answer] Since they have electricity and I assume some spare wire they could create a coil to magnetise a needle or something equally small. They now should have everything they need to build a [Needle-and-bowl device](http://en.wikipedia.org/wiki/Compass#Needle-and-bowl_device) [Answer] Well, you have vitorian-era electric engines on board. Dissassemble one, pick up the magnets that are used inside it, and build a new compass. Anyway, in the comment thread on your other question, you said that "since the airships spend so much of their time above the clouds, only a small percentage of the fleet needs to be docked at any point in time", so this is not really an issue. Above the clouds you always can see the sun/stars and orient yourself. [Answer] Even that far north, during polar day, they can establish north/south by the length of the shade of a vertical stick. Longest shade points south. Sun is highest when south - will make shortest shade. You need fairly even area (no inclines). Middle of the winter is similar: find direction when sun emerges over horizon, where sets, and divide in the middle - it is south. All you need is unobstructed flat horizon - so in mountains you are screwed. And stars! Even during polar night (which could be twilight because sun is just under horizon), you can see bright stars like Vega. But people would not adventure far away during winter - too cold, too windy. Hunker down and hunt seals. Explore in summer instead. Others provided navigation if they have access to technology. My solution is useful when they get stranded, airship crashes, and they need to walk home. [Answer] Some good answers already on navigational methods, but there's one question - and it's a non-trivial question if you're being realistic - that you will need to answer: *what kind of charts would your airships be using?* And by "kind of chart", I'm referring to the [cartographic projection](http://en.wikipedia.org/wiki/Map_projection) used to turn a spherical planetary surface into a flat chart. This is important because there will be **no preexisting charts of the new regions south of the mountains**. Your protagonists will have to include at least one kick-ass mathematician and one kick-ass senior naviator (possibly the same person) who will need to be able to draw new blank charts with Lat-Long graticules on them, on which position fixes may be plotted. In our world, [Mercator projections](http://en.wikipedia.org/wiki/Mercator_projection) have been the preferred navigational chart: they create a rectilinear grid in which direction is always accurate. These are huge advantages (as I can personally attest, having navigated at sea for some years.) However, Mercator projections do not work in polar regions. If you are operating close to the pole, you will probably want to use a [Polar Azimuthal Equidistant projection](http://en.wikipedia.org/wiki/Azimuthal_equidistant_projection), which isn't bad for practical navigation - as long as you don't get too far south. In this kind of projection, meridians of Longitude are straight lines, and parallels of Latitude are circular arcs. So, what sort of map would your civilization have built? Too far south, and Polar Azimuthal projections get less useful; too far north, and Mercator projections cease to exist at all for practical purposes. More importantly, what traditions of navigation would your Northern civilization have? If the airships have been traversing the polar regions, they would have likely settled on polar azimuthal projections; if they have been keeping out of polar regions, they would have been able to develop a tradition of using the somewhat superior Mercator projection. Either way, it's going to affect the crew's priorities and their ability to determine where they are. This will presumably have a big effect on your story... [Answer] Other more reliable methods are listed...but as an alternative, a weather watcher should be able to figure it out. The polar region of the globe has a much stronger and predictable wind pattern that doesn't fluctuate much. This polar Jetstream can be used to determine direction...not very accurately, but the winds will always be from the west as it circles the pole. This isn't as true on land, but in the air, it's very steady and can reach speeds of 160 km/h. A couple wiki quotes: [b] The strongest jet streams are the polar jets, at around 7–12 km (23,000–39,000 ft) above sea level [/b] ![wiki](https://i.stack.imgur.com/2twEv.jpg) Also of potential interest to your story line as it would play absolute havok with your airship...copied from wiki on Jet Streams: Polar night jet[edit] The polar-night jet stream forms only during the winter months, i.e., polar nights, of the year in their respective hemispheres at around 60° latitude, but at a greater height than the polar jet, of about 80,000 feet (24,000 m).[60] During these dark months the air high over the poles becomes much colder than the air over the equator. This difference in temperature gives rise to extreme air pressure differences in the stratosphere, which, when combined with the Coriolis effect, create the polar night jets, racing eastward at an altitude of about 30 miles (48 km).[61] Inside the polar night jet is the polar vortex. The warmer air can only move along the edge of the polar vortex, but not enter it. Within the vortex, the cold polar air becomes increasingly cold with neither warmer air from lower latitudes nor energy from the sun during the polar night.[62] [Answer] Finding direction from the sky is trivial, sun and moon have predictable paths with clear directions and the rotation of the planet gives the appearance of the stars rotating around a specific, easily recognized and well known, point in the direction of the pole. Determining your latitude after getting lost is also trivial. You simply measure the angle of the "pole star" mentioned previously or the highest (noon) angle of the sun. One is pretty useless without precise instruments near the poles and other near the equator, but there should always be atleast one simple way to measure latitude available. Presuming you know the relevant angle for your target at this date and the correct date, of course. This tells whether you need to go north or south to get back to known area. Longitude, which tells whether you need to go east or west to get to a known location, is much harder. There are basically two usable solutions. If you have clock set in the time of a location of known longitude, you can simply check what time it shows at noon to determine relative longitude. Accuracy depends on the accuracy of the clock. It seems likely your victi... characters would not have a precision chronometer required to get accurate longitude, but neither would they need one. They simply need to know whether to turn right or left after returning north enough, right? Ordinary clocks should be able to give them that, if each step of travel is short enough to avoid the inaccuracies of the clock from accumulating. An airship capable of flying above the clouds does not need accurate positioning to find a target near a major mountain range with recognizable peaks. If for some reason they do not have a usable clock, say, some idiot put the clock in local time before anyone estimated the longitude or the clock stopped during the storm, there is an alternative method that is based on using the location of the moon to get a location independent time and then using the positions of the stars to get the longitude. But it requires knowing the relevant astronomical data and knowing how to use it. Ships used to carry this data just in case, but if your people are not supposed to engage in long distance travel, they wouldn't have this. An astronomer or astrologer might have the data and know how to use it. It should be noted that a compass is really only useful for navigation by "ded reckoning" or by keeping track of distances and directions traveled. An airship can only use this, if the crew can see the ground and measure the distance. As such it would be useless to an airship that "lost its bearings" in a storm. [Answer] Given late Victorian-era technology, it's not unreasonable suppose your engineers could build a gyrocompass. In our history, practical versions were patented in 1906-08 <https://en.wikipedia.org/wiki/Gyrocompass#History> So your airship is equipped with one or more, and the magnetic compass is not needed. ]
[Question] [ **This question already has answers here**: [Would a non-round eye, one that doesn't look like a circle from the outside, be possible and functional?](/questions/232426/would-a-non-round-eye-one-that-doesnt-look-like-a-circle-from-the-outside-be) (6 answers) Closed 4 months ago. I have a sci-fi-like universe and one of the species has long, vertical eyes. [![A diagram of the eye I am attempting to describe.](https://i.stack.imgur.com/Lntk7.jpg)](https://i.stack.imgur.com/Lntk7.jpg) But would this be anatomically possible without a sphere-like structure? I know that compound eyes are a thing, but how "flat" can they be in 3D? Like how anime girls have ginormous eyes that, anatomically speaking, would leave no room for brain. (Which isn’t an option for my species, as they are highly intelligent.) How would I design their eyes? Do I need to change the shape, create a custom structure, or search more for other existing types of eyes? [Answer] Eyes do not have to be round, but you have to ask yourself what the "pointing" mechanism is. How does the eye shift where it's pointing? For a human, our eyes can move around in the socket, and the socket moves around with the rest of the head. This flexibility allows us to concentrate our retinal capacity on a relatively small, high-density patch. The skull socket provides protection and image stability. There are many species that can't rotate their eyes in a socket at all. There are a few strategies for compensating. Flexible necks/stalks and numerous eyes are the most common strategy. Your creature looks like it has a vertical slit that the eye can travel along. Perhaps the top and bottom of the slit have different viewing angles, so the creature can pull its eyes to the top of the slit if it needs a wide viewing angle, and can pull them to the bottom of the slit if it wants binocular vision. This mechanism would basically be a completely internalized eye on a stalk, with the connective nerves pulling back like the tongue of a chameleon. You would want to consider the mechanism by which this creature could look up and down, since this scheme doesn't provide that. [Answer] ## Those are just markings, not actually long eyes The tell-tail iris & pupil in the middle actually very much implies that your alien has round eyes that are much smaller than they appear. So one distinct possibility is that the long slits are not actually part of the eyes themselves, but a separate adaptation. **I can think of 3 likely reasons for an animal to evolve this particular feature:** 1. It is a glare reduction feature designed to reduce how much sun shines off of its face blurring it's vision like the markings on a cheetah or racoon. The slits appear red instead of black because the alien can not see in the red part of the light spectrum; so, to the alien, these slits are essentially black. [![https://en.wikipedia.org/wiki/Raccoon#/media/File:Raccoon_(Procyon_lotor)_2.jpg](https://i.stack.imgur.com/Oh8mB.png)](https://i.stack.imgur.com/Oh8mB.png) 2. It is a light or sound collection feature like the discs around an owl's eyes used to amplify one of its senses. For sound, it could have small tympanic membranes at the tops of these slits, and their slits basically function like ears. For light, it could be that these aliens only see in the Red/IR part of the spectrum; so, to them, this is a white reflective surface designs to help collect a wider area of light in low-light conditions. [![https://upload.wikimedia.org/wikipedia/commons/0/0f/Portrait_of_owls.jpg](https://i.stack.imgur.com/tTlTe.png)](https://i.stack.imgur.com/tTlTe.png) 3. It is a form of protective mimicry meant to make it look like it has huge eyes so that when a predator spots it while its hiding, the large eyes would make it think it is part of a much larger creature like the spots on an certain kinds of butterflies. [![https://en.wikipedia.org/wiki/Owl_butterfly#/media/File:Caligo_martia_(ventre).jpg](https://i.stack.imgur.com/2DT7F.jpg)](https://i.stack.imgur.com/2DT7F.jpg) Either way, it may be much simpler to explain these as an illusion than actual eyes. [Answer] > > (...) I have found myself with an issue: would this be anatomically possible without a sphere-like structure? > > > Yes, it would. Land vertebrates have round eyes because that shape helps keeping the fluids inside with well distributed pressure. Notice that eyes are not perfect spheres - in humans, for reference, the thicker your glasses are, the more flattened your eyes are. Fish eyes are flatter. Look at the eyes of soles and flatfish. > > I know that compound eyes are a thing, but how “flat” can they be when seen in 3D? > > > As flat as you want. Also as weird as you want. Some trilobites had cylindrical eyes coming out vertically from their heads, and made of crystal (calcite) on top of that. --- Looking at your creature in the drawing, what I see is a small, green, quasi-spherical, flattened eye on each side of the head. The red parts around it are two large caruncles, which are not part of the eye per se. [Answer] You might want to consider something inspired by [octopi](https://www.theguardian.com/science/neurophilosophy/2015/may/20/octopus-skin-contains-light-sensors) -- ie., a mix of shallow [eyes](https://www.frontiersin.org/articles/10.3389/fphys.2019.01637/full) and light sensors embedded into the epidermis in clumps. The octopus structure technically allows for any kind of surface shape for the "eyes" (they can be pretty flat and still work). And extra light sensors in the epidermis then will make up the difference if the eyes themselves aren't powerful enough or otherwise sufficient [Answer] The ability to move eyeballs does not come for free. It is anatomically *much* more complex than an eye that is fixed in one position, and it also requires more brain power to process visual information when there are additional factors complicating it. You eg. have to deal with changes in parallax (when you are looking sideways without turning your head, your eyes are effectively closed to each other than when looking forward), and you also have deal with both head position *and* eye position together. This goes because there are two big benefits: 1. ability to see both close and far away, and 2. speed and accuracy. 1: The resolution in the eye is not typically uniform in creatures on our planet. Density of cells near [macula](https://en.wikipedia.org/wiki/Macula) ( the part of your eye that processes what you see directly in front of you (your central vision) is much greater than in areas elsewhere. Near the edges, resolution is quite low. This is not evident, though, because your brain masks it in the same way it hides the [blind spot](https://en.wikipedia.org/wiki/Blind_spot_(vision)). If your eyes can move, you only need one area with increased resolution. You can point your eyes easily towards where you need it. However, if you cannot move your eyes, you either need to have much larger area with increased resolution or live with not being able to see well both near and far, you have to choose one. Note that looking both close and far ways is not covered only by adjusting the lens of they eye. We cross eyes when looking near because of this. 2: Eyeballs are lightweight and therefore much much easier and faster to turn than a head, and it is much easier to make it accurate. You can orient your eyeballs several times in the time it takes to turn your head towards an object of interest. The alternative solution would be wider field of view. Your aliens lack both. They have vertical slits, and no moving eyeballs. They have a problem if they get surrounded: they are effectively half-blind because they cannot keep monitoring their environment as effectively as creatures with moving eyeballs or wide field of vision. They need to turn their head constantly, and turning head reveals in a loud manner where their blind spots are, and because turning the head is also slowish, the enemy can take advantage of this shortcoming. --- I am not saying that your eye design is completely implausible, though. There are just some issue with that kind of eye, but you might be able to work around them. Also, you can address some of the functional shortcomings in their anatomy like people complain about their back (the spine works well in aquatic environment where it evolved, but not on land, and even less so in an upright position). [Answer] a look at the [eye of the Mantis shrimp](https://www.nationalgeographic.com/science/article/mantis-shrimps-have-a-unique-way-of-seeing). This is a compound eye, so it does not need a spherical overall shape. It is about as hardcore bonkers as the rest of this animal. Birds such as owls have binocular vision, but their eyeballs [are not round](https://www.owlpages.com/owls/articles.php?a=5). This is more compact than a spherical eyes, but they cannot pivot the eyes in their orbit. Most of the optical surfaces are approximately spherical. There are plenty of other weird eyes out there - these were just the first two that came to mind. ]
[Question] [ In my medieval setting, bird people are about half the height of a human, have hollow bones, and have hands at the end of their wings. In warfare, there are 3 types of avian units: * Scouts give the commanders a birds eye view of the battlefield, and give out orders to the troops. * Droppers (the name is a work in progress) drop flechettes and rocks on the enemies. * Fighters fight for aerial supremacy, and are armed with metal talons. Also they are used during sieges to assault enemy battlements. The bird people live in nomadic tribes, and often work as mercenaries. All countries use avians of some kind, be they bird people, bat people (pretty much identical to bird people except they live underground), or giant ridden bats. Dwarves for instance fight in massive tight pike squares with miscellaneous weapons inside, and crossbow archers to the sides. Since they only have a limited supply of bat people, they only use scouts, and fighters, who provide their main protection against droppers. The elves have the highest supply of bird people, so they use their aviation to the fullest. When it comes to land units, they entirely use cavalry and mounted infantry, in the form of longbow archers. When fighting against dwarves, they use the archers to weaken outside, and droppers to weaken the inside, before charging in with heavy cavalry and war animals. I wish to get feedback on whether my approach has any problems, or is overly simplistic. [Answer] I don't see anything out of the ordinary or which stands out as implausible. You are basically mirroring some of the uses of aviation in modern warfare, leaving out only transportation: recognition, air to ground attack, air to air attack. The air to ground attack role will probably be limited by the load which they can carry: since it relies only on kinetic energy to produce damage, you will need to find the sweet spot which balances number of dropped objects and their mass. Too few and too heavy can be easily avoided or won't hurt enough targets, too many and too light will not reach a high velocity. Another role that you might use is biological warfare. Not only the traditional "drop a rotting corpse", but also a more peculiar one: if they are infected with cholera and/or typhus, they can use their own droppings to infect the enemy troops, cities and related water reservoirs. Particularly useful when besieging a city. [Answer] These are the traditional roles for aircraft, so you're on the right track, but consider the actual capabilities of the bird-people. A bird-person soldier will be badly outclassed by any human soldier, militia, or probably even a cook with a kitchen knife. The human will be physically larger, stronger, able to endure more wounds, and able to carry much heavier weapons and armor. There is an additional problem: while flying units can easily go above the effective range of arrows, if they come down to fight, they are very exposed. Archers on the battlements would be extremely effective against bird-person fighters. Using the bird-people as air cavalry or siege units is probably not viable. They could be more useful as assassins or for infiltration, since they can get into unexpected places. The comparison to WW1 flechette dropping has already been made, but I would expect the bird-people to be much more successful at it. WW1 pilots were trying to do it while flying awkward aircraft, from angles that were not a good natural fit for the human brain's evolved ability to throw things, and without being able to clearly see what they were doing. Bird-people will naturally be more skilled and will be in their natural environment. However, the inherent weakness of flechettes as a projectile will come into play. If gunpowder exists in your setting, it will be more effective for them to drop grenades. Also consider the biology of the bird-people. If their hands are on the ends of their wings, they won't be able to use them while flying. They probably won't even be able to hold anything while flying. To see what I mean: flap your arms, then hold a one pound weight in each hand and flap your arms. The droppers will probably have to do something like wear the flechettes in a belt pouch, and then pull a string to release them. They would have a hard time even reaching down to release the flechettes without losing control. This also applies to the fighters, who would have trouble wielding their talons. Real-world hawks that do air-to-air predation use their feet to grab prey. Pelicans use their beak. No birds that I know of can do anything else with their wings while flying. It might work better for the bird-people to use their legs to power their flight, leaving their arms free to do things - or at least they could kick each other, rather than use their hands. [Answer] This sounds perfectly reasonable. You list three things fliers are good for and then say they are used for that. The thing that makes or breaks the realism is (a) how the presence of fliers changes the warfare at a fundamental level. Medieval open battles were rare but sieges were common. It is easy for a few dozen people in a castle to hold off an army of thousands. Not any more. and (b) the logistics of fliers. As always remember: [![Portrait of Napoleon Bonaparte with the quote "The amateurs discuss tactics: the professionals discuss logistics"](https://i.stack.imgur.com/SPkg4.jpg)](https://i.stack.imgur.com/SPkg4.jpg) You have a platoon of flying soldiers, but they cannot have a flying supply wagon following them. So they need to be escorted by a land wagon to get far from home. They cannot fly deep into enemy territory without starving or raiding the villages for food and water. [Answer] Looks pretty okay - there's 2 areas that spring to mind: 1: a modification of your droppers, which would be Assassins. Taking out HVTS (High Value Targets) like Generals etc. They could use the same weapons as your standard droppers - or, more likely, they equip specialist weapons to take out such an individual. 2: infiltration. Think of a Castle with high walls and a barred gate. Something where an individual who could get inside could raise the gate. Now, our flying humans aren't robust enough to storm a castle or engage in Melee combat with full size humans - so they would be limited to sneaking in, weakening the defenses/lowering draw bridges/raising gates and then withdrawing so the conventional forces can engage. [Answer] To fully grasp what military purpose bird people would have in your settings you have to play the thoughts back and forth a few times. What is the strongest use for bird people? How would/could that be countered by ground units? For example when considering your droppers, you should also consider what tactics and weapons would be employed on the groundside to counter them and again what the bird people could do against that. Bird people dropping stones/flechettes from low hight for good precision would lead to: Ranged weapons used as anti air. For example scattershot mechanisms. would lead to: bird people flying higher and thus becoming less accurate, changing the target from single enemies to tight groups and bigger targets or dropping other weapons that need less accuracy like oil and fire would lead to: ... and so on and so on also always remember: combat on the battlefield is only one facette of war. there are a lot of others. Intelligence, logistics, morale, position... [Answer] As is, your avianoids would only be able to use what can be carried in each wing-hand or can carry as a payload via foot-claws. Lets do some fuzzy math on how much they could carry and how effective a dropper would be: Aside from outlying apex birds, most birds can lift, at most, their own weight and cannot fly far when that heavily burdened. Larger birds bones make up about 8% body weight. Average human weight is ~160 lbs (depending on region), with ~14% of that being bone. Bone density, then, accounts for a 6% weight difference. You say they are about half a human, in size, so ~80 lbs minus 6% (4.8 lbs) to account for bone density, leaves you with a ~75 lb avianod. Fatigue is real, so we'll account for that by comparing average human weight (160 lbs) to average plate armor weight (~50lbs). Thus, the average human can endure the fatigue of about 31% of their weight. Wind/weather conditions being flat, your avianoids would be able to to carry a payload of about 20 lbs (or 400 oz), on each drop. Flechettes used in WWI were ~0.7 oz, meaning each bird would be carrying a payload of 571 flechettes. While I originally set out to show logistical non-viability of a single dropper making a pass over ground units, I believe I've shown the contrary. Flechettes used in WWI could build up enough velocity to pierce a helmet, so it is safe to assume they could pop through some armor with a decent rate of success. A single flight-run of 5-10 droppers would drop 2855 - 5710 flechettes. Even if only 1 in 50 hit and no hits are fatal, that's a good 57-114 wounds per run. Not terrible. Other things you might consider: * Partial or full detachment of the avianoids arms from the wing. The [Pathfinder 2e Strix](https://2e.aonprd.com/Ancestries.aspx?ID=40) is a good example of this. * Dropping caltrops, tar (heh, tarred by feathers), or netting. * Dropper efficiency would go down per run, accounting for eliminated opponents. * Droppers are going to be pretty useless after ground units have engaged each other. * How are droppers going to resupply (or are they a 1-and-done kind of thing)? If they are resupplying from the ground forces, don't forget to account for guarding the supply and the possibility of having opposing units capturing that supply for their own use. What's to keep enemy units from carpeting the supply, then using it to have a closer supply line. ]
[Question] [ ## Backdrop In the ending of my book, the closing scene is the control room of the mangled and torn-up starship diving into the atmosphere (maybe not so dramatic) on its fusion engines, slowing down and sliding with a sizzle into the ocean, with a view of the capital city, Elysium, and a convoy of choppers with military and first response crews closing in. I was actually more concerned with the closing words of the book, to set the backdrop for the probable sequel, but I realized that I didn't actually know if a starship can **even survive propulsive reentry, let alone slamming into the ocean**. Sure, I can hand-wave a little of the last part because the laidenfrost effect should keep the water off the ship until the inside floods, but I don't actually know what would or would not let such a ship survive reentry. ## The Question Could **any** cargo ship survive slow, propulsive reentry? Assuming that its drives can deliver 1+ Gs of acceleration and won't collapse on impact with the launchpad / space-x-chopstick-arms / ocean. Do note: I am talking about a starship built like the typical sort-of-combat-rated spaceship in the expanse. I would give details about the ships systems but let's just use the expanse because it's simple and the differences are negligible. It has shield panels, engines, maneuvering thrusters, all there usual. [![enter image description here](https://i.stack.imgur.com/Pdfel.jpg)](https://i.stack.imgur.com/Pdfel.jpg) If not, then what is the minimum a ship needs to survive reentering? Intuitively, I'd assume that the only issues would be atmospheric heating and maybe possible issues with a vaccum-tuned fusion engine, but theres also maneuvering engines or strap-on SRBs. Also note: I am talking about a habitable, earth-like planet with a 1 ATM pressure atmosphere, with earth like mass. [Answer] Fortunately, there is in real life a space transportation services provider named SpaceX who routinely and frequently posts on YouTube complete videos of their missions, which in recent years have almost always involved the safe re-entry and landing of (the first stage of) their rockets. If you look at any of those missions, you will notice that the trick is to fire-up the engines just before entering the atmosphere to slow the vehicle down to a convenient speed; they call this the [entry burn](https://youtu.be/nfxyF1_Ylkk?t=1581). For SpaceX's Falcon-9 boosters, that convenient speed is about 3800 km/h (1 km/s, 2400 mph). After the entry burn, they let the vehicle fall freely, and be slowed down by air resistance to its terminal velocity. For your unspecified spacecraft, the entry burn will probably have to slow the vehicle down to some other convenient speed, to be calculated by the engineers who designed it. [Answer] If you have engines that can exceed 1g and you have enough delta-v then your ship has no problem surviving a propulsive entry--you can slow it as much as you need to, the engineers who built it can tell you the maximum indicated air speed (yeah, that's from the world of airplanes but it still is what matters for figuring what the air will do to your ship) it can take without damage and the maximum it can take without destruction (if it's an emergency measure you might not care if a bunch of fragile stuff on the surface gets destroyed.) The bigger issue is surviving your own engines. You say it's fusion engines but you don't specify how they work. What happens when the exhaust from the engines hits the atmosphere (or, even worse, the ocean as you land on it) and some of the energy is reflected back at your ship. Even with our chemically powered rockets this becomes an issue--launch pads have sound suppression systems to keep from damaging the rocket and you're talking about something far bigger and more powerful. I would actually be surprised if any such ship could survive the touchdown. [Answer] **possible, but very hard to do if you want your ship in one, not-crumpled piece** Early in the space race, both Nasa and Roscosmos used Lithobreaking (a fancy space flight term for crashing into the surface of a body) for early moon landers. But since you are working with fusion torch drives, you would probably have enough thrust and fuel to pull off a propulsive re-entry, maybe even a soft landing if you're lucky/bold enough to do it. first, de-orbit, slow down to a few hundred meters a second, if your crew has time to, rig up some air brakes from some spare hull plates or the doors on a cargo container. then strap in everyone to crash couches, preferably at the highest point in the craft, keep the drive going but at an acceleration that's only enough to keep you below supersonic speeds, if you run out of fuel for the fusion drive, go max power on the forward RCS thrusters, if those runout, pray to god that the lower decks will crumple enough to slow you down to a halt while also not crushing every living thing aboard. If you have a back-up propulsion system that's not an Ion thruster, save it for a few thousand meters above the ground/sea level to perform a suicide burn, this is the most optimal outcome, ignite it and keep the thrust steady. If you somehow survived all that, great! salvage what you can from the ship's supplies, call for help if you can, and wait for rescue, or starve to death. DO NOT LAND IN THE SEA, water at that speed for any object is just as hard as concrete, at least on land the guys who manage to survive can retrieve supplies and call for help from the remains of the ship. I'd also make a make-shift parachute deployer+parachutes for added deceleration in atmosphere [Answer] With a drive able to accelerate the ship with 1+ G, the ship could decelerate before touching the atmosphere to come to a relative stop and descend at a snail's pace, limiting stress due to landing to a minimum. Since it (hopefully) is build to withstand it's own drive's acceleration the ship should be strong/sturdy enough to not break apart under it's own weight, as long as it is correctly oriented (the main drive pointing towards the planet). The main issues I see would be * is there enough fuel to land that slowly? * keeping the ship at the right angle - presumably a ship that is not supposed to land on planets might have no computer aided program for that. But for a story those "issues" are probably more productive then problematic - *not* having enough fuel to do it quite the easy and safe way sounds a lot more exciting. And the words "The computer can't do this, we'll have to fly it manually" are practically mandatory for every story involving cool space ships. ;) ]
[Question] [ The Tharsis range is a quartet of immense volcanoes on Mars, one of which, [Olympus Mons](https://en.wikipedia.org/wiki/Olympus_Mons), is largest in the solar system. It is so vast that it cannot be seen from the surface; should you stand it’s slopes, the peak would be beyond the visible horizon. It’s crater is comparable in width to Paris. When people set about terraforming Mars, the first thing they do is melt the core. (Don’t ask how). This melts the mantle in turn, which Olympus mons is still partially connected to. This raises the possibility that the volcano will become active again, which begs the question: *what happens when the largest volcano in the solar system erupts?* [Answer] A quick google search revealed the following. Olympus mons is what is known as a shield volcano. Shield volcanoes are classified as very large with broad slopes. Volcanoes like Olympus mons would create many large lava flows and would have limited amounts of explosive eruptions [Answer] # Olympus Mons cannot erupt There is one reason for this, which is really weird, but is real- **You need water to make magma** Strange indeed, but this is what happens on terrestrial volcanoes. Volcanoes occur mainly due to tectonic activity (Ignoring mantle plumes for now), more specifically, the pushing down of the oceanic-plate, by the above land-plate. This means that the oceanic crust is driven down by the land crust, into the mantle. However, at the same time, water also seeps along with the plate into the mantle. Remember that this was a oceanic crust being driven down, not the land crust. Now, as water enters the mantle, it [catalyses a series of reactions](https://www.google.com/amp/s/www.imperial.ac.uk/news/198796/study-reveals-water-deep-earth-triggers/amp/), that causes the mantle material to decompress and become a liquid, i.e. becomes magma. This liquid magma builds up under the crust, creating immense pressure, until it finally cracks the crust open and erupts out as lava. On Mars, however, there is not much water. Most of the water has evaporated away, and whatever little water is present is present as ice beneath the surface. So, even if your terraformers managed to melt down the core and the mantle, then still Olympus Mons couldn't erupt at all, as there is not enough water to create sufficient magma for it to erupt. Even mantle plumes don't stand a chance. Earth has a thinner crust, due to a larger mantle. This means that mantle plumes i.e. giant masses of mantle material from the mantle-outer core boundary, can easily penetrate the crust, and create massive eruptions, like the Siberian Traps. However, Mars has cooled down significantly, which means that the mantle material has solidified into the crust, and made it much more thicker. In fact Mars' crust is [24-72 km thick](https://www.science.org/doi/10.1126/science.abf8966#:%7E:text=Mars%20likely%20has%20a%2024,probably%20exists%20beneath%20the%20lithosphere.), with a 500 km thick lithosphere. In contrast, Earth's lithosphere is a mere 280 km thick. This means that even mantle plumes cannot penetrate the crust at all, as Martian crust is extremely thick. No eruptions for you, Olympus Mons. [Answer] This is a fun little What If. Let's start by describing what Olympus Mons is. It's a shield volcano, just like the Hawaiian islands. The difference is that the Hawaiian magma plume moves over time. Olympus Mons was the great last gasp of Mars as its core cooled. Over time, the cooling crust got so thick that all of the volcanos on the planet got piled up in the one place where magma could still reach the surface. The simple answer would be that it wouldn't do much. Shield volcanos are notorious for having eruptions where you can walk faster than the lava. Mars would briefly have a thicker atmosphere, and there would be a big ash plume. Or, maybe, there has been pressure building up in the core for a very long time. It had a path to the surface a long time ago, but now all it can do is push harder and harder until the crust splits open like a grape and pours a huge new lava flow basin. That would also be cool. ]
[Question] [ I remember reading about ethanol that's able to be found trapped within rocks, but I sincerely cannot find the source, so here I am. I'm trying to understand how that works. I want to magnify it in my setting for the purposes of some very specific cultural phenomena I won't get into but basically what I'm asking is, how can large amounts of ethanol be found within rocks? Primarily, water soluble minerals that generally form in deposits. I don't think free-standing alcohol would suffice as I am certain it would simply evaporate. [Answer] **I wish I had better news...** > > Ethanol is a naturally occurring substance resulting from the fermentation by yeast of fruit sugars. ([Source](https://pubmed.ncbi.nlm.nih.gov/21676715/)) > > > Why do we use corn? Because we can produce so honking much of it compared to the higher sugar content of fruit that the lower efficiency of corn becomes irrelevant. I tried to hunt Google for any reference to ethanol or alcohol being trapped in rocks. I came up with nothing. If ethanol occurs underground, it would occur due to the decomposition of biomass and wouldn't last very long. I kinda doubt any alcohol could last very long bound in any rocky substance. Even if it did, I'd imagine that it would evaporate long before it could be captured via (\*ahem\*) ore processing. On the other hand, I'd like to recommend *[The Alcohol Textbook](https://edisciplinas.usp.br/pluginfile.php/2993570/mod_resource/content/1/The_Alcohol_Textbook-%204%20Ed.pdf).* Download that throwing-weight document and turn to page 41, then start reading. You'll get a better-than-average overview into ethanol and potential future sources. [Answer] ## Molecular sieves / zeolites AFAIK, JBH is right; there are no alcohol containing rocks in nature. Jed Clampett can't shoot 3 raccoon lengths to the left and become a beer baron. This answer won't give you a great alcohol rock, but it can work with a little effort. There are minerals that will adsorb small amounts of alcohol and hold it strongly enough that it is not readily eaten by bacteria. They are zeolites and/or synthetic molecular sieves. You either need to dehydrate natural zeolite at 170 degrees celsius and then soak the alcohol in, or make the synthetic zeolites and do the same thing. Synthetics have to be manufactured in autoclaves using organic templating agents, but they hold a lot more booze. If they have the opportunity to hold water instead, they will take it, so getting them dry is necessary. To release the alcohol, heat the zeolites at just above alcohol boiling temperature and capture the gas, or slowly seep water through it, displacing the ethanol as water adheres to the binding sites. Other inorganic sorbents like activated carbon or special clays might work, but probably not as well. ## Sodium ethoxide You can react alcohol with sodium hydroxide to make sodium ethoxide. It's a white solid that's effectively 70% alcohol by weight. It's what used to be on those little refreshing KFC napkins many years ago (in my country anyway). Add the correct amount of an acid (e.g. citric acid) and you will get an alcohol solution, potentially even a strong one. [Answer] As other answers have pointed, out a sustained process for producing and entrapping alcohol in rock would be difficult to explain, but perhaps a one-time natural catastrophe could fit your story line. Consider a large orchard or natural formation of fruit bearing plants where in late summer/early fall there is a lot of fermenting fruit on the ground that is subsequently covered by a land slide. Sealed off from oxygen, the fruit ages like a fine wine for decades until the seam is discovered in the hardened sandstone. There may be other compounds present that would disrupt the flavors or make the fruit go bad during this time, but something to consider depending on how chemically accurate you wish it to be. [Answer] There are methane pockets in permafrost, coal seams, and all the usual places you'd find natural gases. There are methods, using zeolites (like Sean said), to convert methane to methanol that might occur naturally. Of course methanol is not the thing you want, it's the "bad" alcohol. Either way the only way that pockets of ethane/ethanol or methane/methanol would last any length of time would be in protected environments that would either have high pressure (think geysers that spray oil and gas when punctured) or low temps (frozen under ice or permafrost). The freezing point of ethanol is around -110C (at 1 bar) so it would have to be cold like the poles of Mars. The stuff is volatile so would end up out-gassing or evaporating given any chance. ]
[Question] [ In my world, World War 3 happens and most countries are devastated. Nuclear weapons are used and there is widespread anarchy in many places. Some countries are untouched but many countries completely collapse and other nations are reduced to a 19th Century or even 18th Century technology level. I was wondering if feudalism could make a comeback in a world that still has limited modern knowledge and technology. By feudalism, I mean there would be a king that nobles would swear fealty to. These nobles would own farmlands that serfs would work on. And the nobles would receive produce from the serfs in exchange for military protection from bandits and other nobles. On one hand, there is no particular technology that obsoletes feudalism. On the other hand, there is probably a good reason that no modern-day country uses feudalism as a socioeconomic or political system. Could feudalism be feasible in a decentralized semi-modern country in an unstable world? Or does the Industrial Revolution or certain modern ideas condemn feudalism to the history books? [Answer] Feudalism could make a comeback only if the population and level of technology declined so much that the majority of people would be working in farming. Merchants, traders and skilled craftspeople are much harder to control than peasants who are bound to their land; if people in bourgeois professions don't like the local regime, they take their business elsewhere. Industrial workers can also easily switch between jobs. Feudalism becomes impossible or at least impractical and unlikely when industry and business become a major part of the economy, generating more income than farming. Central government is then needed to impose the same laws and rules everywhere. Adoption of democracy is also related to the rise of the middle class. To keep the wealthy middle class happy, it must be given some influence in how the country or other jurisdiction is governed, thus some kind of democracy usually appears. [Answer] The effectiveness and efficiency of feudalism is not directly related to 'industrialization' or the level of technology per say. The fall of feudalism was a direct result of the rise of urban centers and cities, and the rise of the merchant sector and industrialists. Merchants and craftsmen had no loyalties to any local fiefdom. Their domain was the urban setting, where land ownership followed a distinctly different paradigm. (However, it can be argued that industrialization and technological advancement was what created the urban environment and the rise of merchants, industrialists, and craftsmen in the first place.) The urban landowners made their wealth from renting to workers and laborers, who worked and labored for entities unrelated to the landowners. The residents of tenements were not employed by their landlords, in the same manner as peasants were 'employed' by feudal lords. ('Contracted' rather than 'employed', there was no such thing as an 'employee' in the feudal system, no such term, in fact. The closest term to employee/employer was 'slave' or 'servant'. In point of fact, a lot of what is referred to as 'slavery' or 'servitude' back then was what we call 'paid employment' today - there was just no other term for it. The concept of 'employment' did not really arise until industrialization. Until industrialization, there was no concept of 'payment for a unit of labor time', only for 'specific services'.) The feudal system can not work in an urban environment, unless the 'town' is a purely corporate town (all lands owned by the corporate entity/employer, not a generic landowner/landlord, and rented to the workers of that corporation). In point of fact, the corporate town is perhaps the closest example of a feudal system in an urban merchant/craftsman environment. So to the extent that a corporate town can be considered a feudal system, then 'modified feudalism' could be possible in an industrialized urban setting. Another point to be made, is that feudalism was a stateless system. That is, there were no defined state borders under feudalism. Sovereign states and statehood did not exist until after the Peace of Westphalia. (Germany did not become a 'state' as we understand it today until Kaiser Wilhelm, and the late 1800's early 1900's. Until then, it was a collection of locally-owned and governed 'kingdoms' with very limited 'state' oversight.) The only true borders were the borders of the estate or Fiefdom, and they were enforced by the power of the lords, not any legal or rules-based 'real estate' system. Under the feudal system, Kings ruled a collection of fiefdoms, not specific 'states', and were more cultural/social institutions rather than military/policing institutions. The Court was the center of socialization and diplomacy, the King a figurehead of the Court. In order for there to be any official or formalized 'land title' or 'land ownership registration', there has to be some form of 'collective oversight' wherein the land ownership can be formally registered with. That was the purpose of the King's Court. It gave credence and credibility to land claims. For your system to work, would require the demise of the modern 'sovereign state' concept, and the degeneration of statehood and state borders. This, of course, would be a byproduct/artifact of the general anarchy in a post-global-conflict society. [Answer] **Feudalism and industry is *difficult*, not *impossible.*** The core of feudalism is that, *in theory*, the monarch owns most of the means of production and more-or-less permanently gives them to henchmen in return for personal loyalty and defined services. These henchmen then temporarily give part of their gift to their henchmen, all the way down to the serfs at the bottom. * The 'means of production' are mostly agricultural land, but also the right to catch fish in some lake or river, the right to build a brige or mill, etc. * In theory, the fief is given temporarily. In practice, the relationship is inheritable. * Services are defined in the feudal 'contracts.' One fat pig by Michaelmas, two weeks labor during harvest (while the lord provides bread and beer on those days), etc. The serf could not switch to raising cotton, or work in a factory, because *a pig* is owed, not the value of the pig. This started to change at the end of the feudal period, but changing it was a drawn-out process due to the inheritable nature of the 'contracts.' * Each level of nobility skims enough to live in the expected style. For a knight ruling over a few hamlets, this might not be much better than the living of the more prosperous farmers. * Note that I used male pronouns for the historical case, because service usually included military service for a set number of weeks, to be performed by men. *Yes, there were a few exceptions. But overwhelmingly, we're talking about men.* But in my first sentence, I talked about *personal loyalty and defined services.* The bullet points mostly talked about the *defined services* going up the chain, and ignores the principle of mutual loyalty, which was the theoretical underpinning of feudalism. Consider a more extreme form of [paternalistic conservativism](https://en.wikipedia.org/wiki/Paternalistic_conservatism). * Imagine a society where factory owners are expected to provide company housing, and company stores, and company schools, as a privilege and not as a means of further exploitation of the workforce. These services are part of the job contract, and quality is expected to be *better* than on the free market. Employees would be much more reluctant to change employers if that means they have to move housing, and that their children have to go to a different school. * Imagine, and that is unusual for our view of feudalism or early industrialization, **that employees can only be fired for very good cause** involving employee misconduct. The employer is expected, by the legal system and by society, to provide pensions, to maintain employees during time of economic downturns, etc. * Children of employees would go to the company school (see above) with the expectation of learning the company trade, and getting a job. There may be options to switch, but for practical purposes, most jobs are inheritable. * Find a solution for families with different employers. Does one of them transfer? Does one of them become a homemaker? Do gender roles affect this? * Imagine further that in business-to-business deals, the legal system holds the general contractor responsible for the details of the operation of a subcontractor. The response could either be to do things in-house, or do develop a stable, mutual trust relationship between general contractors and subcontractors. [Answer] Feudalism makes sense with weak central power that can't effectively tax directly its population and raise a standing army, so shifting this task and power to local elites is the way to go. After having a nuclear war, I'd expect a huge ideological shift towards some form of hard core nationalism and militarism, which would naturally evolve in to de facto military dictatorship or in case of countries more used to democracy in to some form illiberal democracy. Fielding a few knights seems unimpressive for a total war. Feudal like arrangement make only sense when: * you actually field really small number of highly professional troops * when you just started uniting your nation back and quite a few warlords were willing to join, but you had to guarantee them a high level of autonomy. So the most realistic explanation would be having total collapse of state institutions, resurgence of de facto warlords and later reaching a compromise deal. But even under those conditions, one would expect more a patchwork state, where quite a few provinces have retained local democracy. [Answer] I suggest the following ingredients to make Feudalism more believable: * a very depopulated world * loss of agricultural productivity. **Loss of agricultural productivity** You need loss of agricultural productivity *and* a tie-in to land for agricultural produce. More on that later. You can have a loss of agricultural productivity by climate reasons. Or by loss of modern technologies, including any and all that make food supply ample. But low agricultural output and low productivity in general, even combined, do not require the foregoing of all post-industrial technologies and know-hows. For example, say 90% of the remaining population on earth is required to produce sufficient food in aggregate. But a highly automated factory complex produce radios with few human input -- sure you always have upstream input but you can certainly have designs that suit simplified inputs. Said factory may be able to produce enough radios for 5% of the earth's population annually -- allowing some to always have new ones and the rest to only work with old radio sets that may become faulty in some way due to age. In this scenario, you could say a lot of technological advancement is included in the production of radio, so much so that very little input is enough to produce for the whole world. Yet overall productivity of the world is low because food is required and food is being a bottleneck for greater economical development. Loss of agricultural productivity can be important for Feudalism. Feudalism was a land-based social order where 1. workers were tied to the same parcels of land all-year-long 2. nobles had the authority and ability to tax production from (larger) land parcels 3. a hierarchy existed to combine tax over large geographical areas and thus support things such as a military that can provide stability and order and some luxury items that helped people feel that the authority was deserved and proper. If people can move around freely and still be a part of a productive process, then they won't be willing to stay under some abstract contract that bind them to some designated noble -- however relatively un-educated they may be. So for the sake of Feudalism, you should tie 90%+ of earth's remaining population to daily working over the same pieces of land. Note that low variability in agricultural productivity is also needed. ie. You shouldn't have a single place that is highly productive and nowhere else that can produce food. If the only place that can produce starch based food is in the UN headquarter building in a city named New York. You can have whatever social order that makes sense at UN. Outside of it, people are not tied with land anymore. That said, a generally unproductive world but a few pockets of productivity -- even within agriculture -- can make for interesting dynamics. Like 0 everywhere vs 100 at one place wouldn't work. 1 vs 2 on the other hand could be interesting. **A depopulated world** A depopulated world does a number of things in Feudalism's favor, including: * difficulty to maintain law and order over vast areas (and the consummate incentive to banditry) * difficulty to maintain education * even more difficulty with aggregate output that feeds into everything above * the same sequence of events could have destroyed the social/national institutions in our real world in the same stroke The implications are self-evident. Without the large population the modern earth has and supports, the historical benefits Feudalism was supposed to provide are not easily replaced via alternatives. They included social cohesion and stability of life. The key is to take away alternatives. What loss of agricultural productivity achieves is that people are unable to move around and be productive other than being peasants of their specific pieces of land. Depopulation takes away plausible alternatives by not permitting individuals with free time. For 90%+ of population, you work your field for 8 hours a day or your starve. Otherwise, when people have free time, they will try to do things that break the current order. Say there is no difference between a republic where a government imposes tax and a monarchy where nobles do in term's of people's daily experience. If you give people free time, given the communication technology, they may still rebel against a Feudal system and put a republic in place out of preference. That's why free time should also be difficult to come by. Perhaps you can also introduce other factors that accentuates the lack of free time. Perhaps, to make agriculture work in that post-apocalyptic world, farming is very complex -- you need recurring efforts to deal with certain side-effects from radiation, maybe add some new micro-organism that people have to work against -- while being unproductive relative to our real world. --- And there you go, I think with some details, Feudalism can become realistic enough. Yet at the same time, you are not restricted in having modern transportation, modern communications, modern entertainment, etc. ]
[Question] [ I planned to have a region on my world that is similar to Mordor, as in a place with near constant thunderstorms and lightning strikes, about 30 times per minute at peak for at least 25 hours at night (the world has a rotation period of 60 hours). The idea came from this specific video [by the Artifexian](https://youtu.be/LifRswfCxFU?t=471). Now I was wondering if such a place could be reliably exploited for energy, especially the lightnings that would strike it so frequently. Would it be advantageous for a late 21st to early 22nd century civilization to establish power plants over there with lightning rods organized in large fields and probably coupled with wind turbines to take advantage of the weather conditions? [Answer] **Yes, with the proper technology** Each lightning bolt carries about [5 gigajoules](https://en.wikipedia.org/wiki/Harvesting_lightning_energy) of energy. This means that harvesting the energy from the lightning would yield about 1GW of energy on average. Assuming that your future civilization uses energy at the same (per hour, not per day) [rate as US house holds](https://www.eia.gov/energyexplained/use-of-energy/electricity-use-in-homes.php#:%7E:text=The%20average%20U.S.%20household%20consumes,kilowatthours%20(kWh)%20per%20year.), this could power about 9 million households. I think there is some [what-if](https://what-if.xkcd.com/archive/) question (or maybe in the book) that relates to how hard obtaining energy from lightning is, but if this is figured out in your setting, it would probably be practical to setup such a powerplant, as it would supply as [much energy as a nuclear power plant](https://www.energy.gov/ne/articles/infographic-how-much-power-does-nuclear-reactor-produce#:%7E:text=Nuclear%20energy%20has%20been%20powering,power%20per%20plant%20on%20average.), but without the radioactive waste. [Answer] Surprisingly, there is relatively little energy in a single lightening bolt compared to chemical energy. 5 gigajoules of energy sound like a lot. But a gallon of gas is about 132 mega joules. So if you put it in that perspective a lighting bolt has the energy equivalent of about 35-40 gallons of gas. To get the 5 gigawatts you would need to capture one bolt per second and have an efficient way to store the energy between bolts. So it is a nightmare of an engineering problem of where to put the towers, or high powered lasers to ionize the air for the lightening to follow a nice path, and very specialized capacitors to release the energy or maybe convert the energy into something like hydrogen and use it some other form later. As well as how to route the energy between towers to where you want it… But as a story idea, sure you could set up a ring of towers find ways to direct the lightening to the towers or route the lightening bolts or their energy in plasma channels and have some way to harness the energy. ]
[Question] [ The antagonist of my story is planning to prosecute a war on as many as three fronts. What historical examples could I draw on to make such an operation seem plausible, even if it's doomed to failure in the end? Are there any best practices that a competent (if insane) antagonist should employ in this situation? Context: * Technology in this world doesn't neatly map to a particular era of real-world history, but is entirely pre-modern (nothing past the early renaissance era). * My antagonist has recently invented firearms/explosives and rudimentary chemical weapons, and has equipped his army with them. No one else has this technology. * The antagonist is fighting nations that have access to powerful magic and is relying on his firearms and chemical weapons to counter this advantage. Detailing the magic he's up against would probably expand the scope of this question too much, but more info will be provided if requested. * This takes place across subtropical/tropical regions. My antagonist's army will have to contend with savanna, subtropical forest, tropical rainforest, and potentially swamp and desert environments. His enemies will obviously have the home field advantage, which I expect will be especially significant in jungle, swamp, and desert. * Two of the nations my antagonist is invading have long coastlines, and one has an abundance of navigable rivers. My antagonist's naval strength is meh but he has strong naval allies. Only one of the nations he is fighting has any navy to speak of. * My antagonist's soldiers have no magic whatsoever, but the antagonist himself is a powerful and intelligent warlock. He is supplementing his human forces with chimeric monsters, which will make up the bulk of his jungle invasion force and provide support as needed elsewhere. * As his trump card, my antagonist intends to deploy a reanimated dragon, though this will take time to prepare and requires access to key resources currently in enemy territory. Due to both lack of knowledge and cultural taboos, there is zero danger of his enemies pulling an uno-reverse and using a reanimated dragon against him. Dragons have been extinct for millennia and the tactics previously used to extinct them are all but lost. [Answer] # The same reason as two front ones Battling on multiple fronts doesn't seem much different from one front even. The only consideration is if you can attack on multiple fronts. Each extra doesn't make much difference. Look at the second world war. There's a ton of reasons for the second front. We can point to the hubris of the men in charge. We can point to the uneasy alliance that existed between Germany and Russia. We can point to the new blitz strategy that was highly effective in attack, allowing for destruction and advancement in a short time with relative few losses. In just that war we have hubris, strategy, diplomacy and effectiveness. Probably a lot more, as it was to give the new reich plenty of space. Romans at one time were fighting on multiple fronts for different reasons. They were just attacked from many sides as their territory became large and unwieldy at the time. But at an earlier time it could be because they had the power to subdue others effectively, making the empire bigger and more wealthy. It could also just be to pacify the enemies. All this to say that it should be easy to point to a ton of reasons why to attack on many fronts. Ego certainly, but a new technology is susceptible to espionage. Fear of not having this power long can help your reasoning for many fronts. You want to expand, subdue, take or whatever else before the power loses it's potency. Take your pick and if in doubt a quick search to any big empire should help. [Answer] The strategy of almost every multi-front attack is to blitz the enemy on one front, neutralize the threat, then move the forces to a second front, and repeat. The problem has always been that the best plans always fall to pieces the moment the first shot is fired. Seems the enemy just does not always co-operate with your plans. [Answer] The crazy warlock seem to have mobility locked up. Best strategy for him to take would be a Blitz as stated before. where firepower and mobility are maximised in his favor. Though add to this, diversionary tactics that will draw away defenders from his targets. Even fake attacks from imaginary armies or fleets. Communications also should not be minimised in this theater. Where your Warlock where though magic or magical beast has a monopoly on rapid communications, ie: intelligence troop movements, deployment orders etc. [Answer] Best practice: (1) Win the wars in series, not in parallel. (So invade one adversary, defeat them, move to the next). This was the Schlieffen Plan. Germany was concerned that France and Russia (on either side of Germany) might attack it from both sides at once. The plan was that Russia, being very large and having poor infrastructure (few trains) would take a very long time to get its army onto the German boarder. Enough time, it was hoped, for Germany to have already defeated France. So fighting one then the other. (2) It sounds like by "war on three fronts" you mean war against 3 separate nations. The number of enemies does not have to be equal to the number of fronts. If our antagonists country is surrounded by the other three then yes it sounds like 3 fronts, but it might not be. Historical Examples: The best I can think of is WW2 Germany. At one point they were fighting on the Eastern front as well as both France and Germany. [Answer] Peru declared war on all it's neighbours simultaneously back in the day. It ended up losing most of it's male population and a big chunk of land. It went to war in multiple fronts because it's leadership were nutcases. Nazis did the same thing. ]
[Question] [ I was thinking of making a world that is filled to the brim with mountains. I'm not saying that the world is just mountains, but the area or terrain is so difficult that it's hard for land vehicles to explore. I don't what else to say since this idea is new to me and I'm having a hard time molding it. [Answer] Countries with land areas mainly consisting of mountains like Nepal, Greece, and some other European countries have relatively small and stable and even declining populations. So I get that if the vast majority of the Earth's land surface was made of mountains the global population would be much smaller due to limits in agriculture. It is much harder to make crops grow in an irregular terrain than it is on the plains. Transportation would be also harder because it is harder to build roads and rails in mountains. [Answer] I'd start by thinking about how those mountains would form. As far as I know, plate tectonics (in the long term) and volcanic activity (in the not-quite-that-long term) are mainly responsible for mountains to build up. To get more mountains than we have on earth, I'd say your planets crust would need to be rather thin (compared to earth), so that tectonic pressure would more readily fold the plates instead of pushing one plate on top of the other. A thinner crust would also increase volcanic activity, further increasing the chance of mountains building up. Add enough water and you've got continents of mountainous islands and island chains (where tectonic plates are pushed together) paired with oceans full of underwater volcanoes (where tectonic plates move away from each other). I'd assume that you'll get a whole lot of tsunamis on that planet. (I'm the wrong person to answer anything about hard science on this topic, though.) [Answer] Lots of thoughts in no particular order If you're thinking of a super Earth, your mountains will be relatively small. A bigger planet will have more gravity that will cause taller peaks to be unstable and collapse (landslides). Smaller planets have relatively larger mountains. For example, Olympus Mons on Mars is 15 miles tall and the Mountain ring on Iapetus is as tall as 10 or 12 miles. By comparison, Mauna Loa on Earth is only 6 miles tall. If you look at the list of tallest mountains in the solar system, the bigger ones tend to be on the smallest planets. Of course erosion also plays a part. Other bodies with bigger mountains tend to not have an atmosphere to cause erosion. I don't have a link or a good source to cite, but it seems to me that most mountain forming processes would be enhanced by a thinner crust and/or increased volcanic activity. Maybe you can have a young planet that hasn't cooled enough to have a thick crust. Then put it through a period of heavy meteoric bombardment that shattered the crust. This would result in higher amounts of vulcanism so you get "extra" mountains and lots of impassable terrain from normal subduction/delamination, impact craters and volcanos. I'm not sure what that does to the atmosphere though. Is it a cool climate because of nuclear winter? Is it a hot humid climate because of vulcanism? How do the seas fair with all the extra volcanic activity? I don't think you'd get run away global warming since these aren't greenhouse gas clouds? Need someone smarter than me to answer those questions. imtaar has a good point about the balancing of the planet. Earth has a wobble and it was made worse by all the dams built in the northern hemisphere. Crazy to think that humans managed to affect the rotation of a planet! But depending the methods you use to get your mountains, you may have to account for some crazy axial procession. Imagine what our planet would be like if the poles of the planet drifted by several feet or even miles per year. GPS would need monthly or daily updates to account for the ground not being where it was yesterday. Astronomical charts from just a few decades ago would be nearly useless. Tropical years could be days shorter than the astronomical year which would mess with planting days. [Answer] How would it affect the geography, environment, and gravity of the planet? **Geography:** There would be loads of mountains. Mountains are part of geography. [Source](https://en.wikipedia.org/wiki/Mountain). **Environment:** See above. More mountains. **Gravity:** Depends only on the total size of the planet. Mountains don't make much of a difference. [Source](https://en.wikipedia.org/wiki/Space_Jam). [Answer] When the tyre of a car is balanced, certain weights are attached at certain places on the rim so that there are no vibrations when the tire is spinning at high speed. Over millions of years, the mountains and other geography is set in such a way that earth rotates in a balanced way. If you suddenly place large mountains randomly, this could unbalance the rotation of earth. In your world, you cannot place mountains in an artificial way. Let them be formed through natural processes. **EDIT** * Mountain roots act like pegs embedded in the ground and **they work as stabilizers for the earth**. * Mountains take part in isostasy, a concept of the gravitational equilibrium that explains the **balance of topographical undulations on the Earth’s surface**. * **Mountains help our climate stay relatively stable** in between catastrophes. As told [here](http://www.endlesspeace.org/index.php?factid=11): > > The book "Earth" by Professor Emeritus Frank Press , is a basic > reference book in many universities . The book says that mountains > have underlying roots. These roots are deeply embedded in the ground, > thus, mountains have a shape like a "peg". > > > Dr. Press explains that Mountains play an important role in > stabilizing the crust of the earth. They interfere with the shaking of > the earth. The modern theory of plate tectonics also states that > mountains work as stabilizers for the earth. > > > As told [here](https://www.britannica.com/science/isostasy-geology): > > Isostasy, ideal theoretical balance of all large portions of Earth’s > lithosphere as though they were floating on the denser underlying > layer, the asthenosphere, a section of the upper mantle composed of > weak, plastic rock that is about 110 km (70 miles) below the surface. > > > This means that an excess of mass seen as material above sea level, as > in a mountain system, is due to a deficit of mass, or low-density > roots, below sea level. > > > As told [here](https://geographyandyou.com/earth-balance-isostasy/): > > Isostasy (Greek, isos: equal, stasis: standstill) in earth science is > used as a concept of the gravitational equilibrium that explains the > balance of topographical undulations on the Earth’s surface. The need > to achieve natural balance or isostasy takes place on Earth wherever a > large amount of weight is present. This weight might be due to a large > mountain, ice from an ice age or even from human structures such as > the weight from large man made lakes > > > As told [here](https://phys.org/news/2020-01-mountains-impact-earthquakes.html) and [here](https://www.utwente.nl/en/news/2020/1/368867/mountains-influence-the-impact-of-earthquakes):. > > The mountains can reduce the power of quakes but also send them to > certain places, making them more powerful than expected. > > > As told [here](https://news.mongabay.com/2014/03/mountain-thermostats-scientists-discover-surprising-climate-stabilizer-that-may-be-key-to-the-longevity-of-life-on-earth/): > > Mountain thermostats: scientists discover surprising climate > stabilizer that may be key to the longevity of life on Earth. > > > ]
[Question] [ My question is simply whether my character as shown in the picture, 1. Would it be able to fly and 2. Would it look believable if it did fly? [![Sketch of some winged being](https://i.stack.imgur.com/KOHFp.jpg)](https://i.stack.imgur.com/KOHFp.jpg) I have seen similar posts but all refer to wing types more specific to birds and I have noticed that bats seem to generally have a smaller wingspan, so I need a specific answer for webbing-based wings. The creature in question is around 6 foot 8 inches tall and each wing is that in length and about 3x his width which is 2.27 feet. As a result, the area of each wing is about 2.27x3x6.8, which is 46 square feet. The skeletal structure is mostly solid in the torso legs arms and head when it gets to the hands and fingers the bones start to become more hollow the further out you go. The claws do not add much weight as they are more similar to fingernails than teeth. [Answer] An actual approximate weight would be useful, but the answers with the data you've given so far are: 1. No, and 2. Sure, see [Dr. Kirk Langstrom](https://batman.fandom.com/wiki/Man-Bat). As evidenced by our representation of angels, dragons, etc., humans are more than willing to buy into the ability of a creature to fly even if it physically could not. As a mammal (I presume), your creature isn't going to have hollow bones, so we should look at the bat, whose bones are delicate and lightweight to get around that fact. The largest bat is the [Giant Gold-Crowned Flying Fox](https://en.wikipedia.org/wiki/Giant_golden-crowned_flying_fox) - a heck of a name! - with a wingspan of ~1.7m, and a mass of 1.4kg. If your putative creature's mass is approximately that of a proportionate weight lifter, you've got (in fermi numbers) a hundred times the mass, and about two-and-a-half times the wingspan. So no. The wings wouldn't be able to support the mass of the body, the muscles would be unable to propel the wings, and the whole apparatus wouldn't work. Looks cool, though. [Answer] The Yale University's [Yale Scientific](https://www.yalescientific.org/2013/03/qa-why-cant-humans-fly) magazine was so nice to calculate in 2013 what wingspan it would take to get a human to fly: > > Thus, an average adult male human would need a wingspan of at least 6.7 meters to fly. This calculation does not even take into account that these wings themselves would be too heavy to function. > > > That is a *75-kilo* human male. Or for Feety people: 22 feet wing to carry 165 lbs. And it adds that the wings themselves were not included in the calculation or even functional. Oh, and we have [the angel question](https://worldbuilding.stackexchange.com/questions/25466/anatomically-correct-angels), which pretty much explains why the mission statements don't work. So, let's critique: * The wings are **way** too short * The wings are by far not having enough area: Wings make lift by the area! * Hollow or very fragile bones are a **must** * Where's the **bird-sternum**?! ## Calculating wings Wings generate a force based on a coefficient $\theta$, airspeed and air density $\rho$, as well as the wing area $A$ $$F=\theta\frac 1 2 \rho v^2 A$$ For simplicity... let's take $\theta=1$ (which is a very simple wing geometry - it *could* be up to about 2), plug $\rho=1.225 \frac{\text{kg}}{\text m^3}$ and $v=3\frac{\text m}{\text s}$ - a stiff walk. Now, balance out the $F=mg$ with $m=75\text{ kg}$ and $g=10\frac{\text{m}}{\text s^2}$... $$A=136 m^2$$ If we assume glider aircraft wing geometry of 12 widths per length and basically rectangular setup, the wings are 3.36 meters tall and 40.48 meters wide - if he crawls through airspace slowly. If we go fast, like... running the 100 meters in 10 seconds (and thus running 10 meters per second), our hypothetical wingman only needs wings a meter high and spanning 12.25 meters wide. With proper Delta-wing geometry ($\theta=2)$ we get to wings 8.6 meters wide and 0.71 meters high... and still requiring an Olympic record run and to be weightless. Yes, we're still ignoring wing weight. Or muscles. We totally ignored muscles and the best geometry to attach them. Like, to have wings flap, you need muscles that pull the arms forward strongly. Which best is done by having them attached along the length of the path. This is why birds have this really odd protruding sternum. Where are those on the beast you create? ## As dictated... The surface area of the wings is approximately 8.33544 m²... with Birdwing $\theta=1$ he needs to run an astonishing $v=12.12 \frac {\text m} {\text s}$ to get off the ground. This is pretty much impossible. With Delta-Wings of $\theta=2$ he needs *only* $8.57 \frac {\text m} {\text s}$ to get lift, which is still rather on the unbelievable side, because of how his wings would give him drag when running. And still, I did not account for the weight of our Bat demon *properly* - the calculation uses a total mass of 75 kilos on a $g=10\frac {\text m} {\text s^2}$ planet, so... no, he is not able to fly, at best get into gliding from a cliff. [Answer] ## Gut feeling.. 2-3 times wing span, more compact, more muscle The posture seems to a bit elongated overall.. The upper body could be less tall, more compact, wider.. overall, don't forget you'll need a wide and strong breast with prominent clavicle bones.. shoulders are good, wing span is *minimal*.. it looks a bit like Lilienthal proportions now, but Lilienthal was a jumper and he didn't mind to live dangerous. My gut feeling says your character could need about 1.5 times this wing span and a good sprint to take off.. and for agile flight, it will require strong wrists ! the hand needs to be bigger imho, the arms and wrist thicker.. with stronger musculature. All that would make it heavier, so consider 2.0 times the wing span shown. **Center of gravity considerations** A humanoid character able to fly would prefer to do that horizontally. As shown, your character is a bipedal dancer, rather than a flyer. Consider drastically compact the body, and try minimize the weight of the back, tibia bones and feet. If you can't.. enlarge the wing span to 3.0 times: when its full body length "hangs" under the wings, the takeoff lift required will be considerable and flight will be slow. ]
[Question] [ I would like to know the state of cobalt on the earth in the year 2100, but I hear that it might run out in 2025 or 2030. Cobalt is used to make electronic components. In a world where most of the countries work with renewable energy it is used to create batteries. Since for my story cobalt is the key element I need this information, or should I ignore this fact and pretend that there will be cobalt available in the near future? Space travel is not a possibility. [Answer] The DRC has enough cobalt to maintain current output for 30 years, and has about 50% of the world's known convenient cobalt reserves (source: [‘Peak’ cobalt is not on the horizon – S&P’s Global Market Intelligence](https://www.miningweekly.com/article/peak-cobalt-is-not-on-the-horizon-sps-global-market-intelligence-2018-07-16)). About a third of the remaining reserves are in Australia (source: [Top Cobalt Reserves by Country](https://investingnews.com/daily/resource-investing/battery-metals-investing/cobalt-investing/cobalt-producer-cobalt-reserves/)). That gives perhaps 60 years at current output, though that only takes you up to the 2080s. It is awkward to find information on unconventional cobalt sources, but such things almost certainly exist because cobalt isn't [vanishingly rare](https://en.wikipedia.org/wiki/Abundance_of_elements_in_Earth%27s_crust), after all. Given a strong enough economic incentive, exploitation of more expensive and less convenient cobalt reserves, and more aggressive reclamation and recycling of existing cobalt, would become viable. Notably, current estimates of cobalt reserves *only look at continental deposits*. There's almost certainly an awful lot of all sorts of valuable minerals at deep sea sites, [cobalt included](https://en.wikipedia.org/wiki/Cobalt#In_the_ocean). As there isn't currently a good survey of deep ocean mineral deposits, there can be as little or as much of them in your story as you need, and they can be as easy (or environmentally sound) to exploit in your future setting as you want. > > Cobalt is used to make electronic component. In a world where most of the country works with renewable energy is used to create batteries. > > > That's true now, but it won't necessarily hold true for the next 80 years, especially in the face of vanishing reserves of critical strategic metals. What's more likely is that alternative materials and technologies will arise that will use other materials that are more readily available and reasonably priced. Such things are already on the way, but they're not quite economically viable yet due to the current availability of the problem materials. > > Since for my story Cobalt is the key element i need this information, or should i ignore this fact and pretend that there will be cobalt avilable in the near future? > > > Do you need cobalt to be scarce to drive your plot? Great! There's a reasonable chance it will be! Would you like your setting to work even in the absence of cobalt? That's fine too! There are plenty of alternative technologies that are either being developed now or will plausibly arise over the next eighty years. [Answer] **Whichever you want** [![enter image description here](https://i.stack.imgur.com/ejGEj.gif)](https://i.stack.imgur.com/ejGEj.gif) Writing a story about cobalt? About damn time! Writing a story about cobalt shortages? Make sure to mention cobalt running out! Writing a story about cobalt but not centered on the shortages? Choose whichever works best for the story. Want them to run out of cobalt? Simply declare that the cobalt ran out. Want them to have loads of cobalt? Simply declare they found other materials to replace it. Things that used to be of cobalt are now made of other stuff. Or they stopped using the cobalt things, and now use other sorts of things. Or declare they found a bunch more cobalt somewhere. Or they started recycling it. For example if you return your old toasters or batteries to the supermarket they will give you a few dollarydoos. By the way what do batteries have to do with renewable energy? [Answer] In 100 years no metal will actually be that scarce. Asteroid mining will unlock an almost infinite supply of raw materials for several centuries. However, even if you don't believe in asteroid mining or don't want to make your people go to space, cobalt is both recyclable (so once extracted you can keep using it forever) and there are huge amounts of it on earth. Another answer has some data about current reserves but on top of that the oceans hide like 10x more (and probably even more that we haven't found yet). [![enter image description here](https://i.stack.imgur.com/VOQFG.jpg)](https://i.stack.imgur.com/VOQFG.jpg) <https://worldoceanreview.com/en/wor-3/mineral-resources/cobalt-crusts/> <https://www.isa.org.jm/files/documents/EN/Brochures/ENG9.pdf> In general, when you read articles saying that we are "running out of x" the claim is mostly poorly based and it's being fueled either by ignorance or by someone's pockets. The only valid point is about the price per unit which goes up as we keeping extracting said material but when there's demand supply will follow, eventually. In any case, if it's fiction you can simply ignore reality and make it be whatever you want. I'd like to make it clear though that by publishing a story where cobalt is scarce, and that scarcity causes problems to humans, you will be part of the problem as cobalt is currently being used by certain people and political parties for lots and lots of fearmongering. If you insist on cobalt please use accurate data (ie not scarce) or focus on some other metal that people don't use to attack EVs, batteries, renewables, etc. Gold is a good candidate. It's actually super useful as it's inside almost every single electronic device and it's orders of magnitude more problematic than cobalt (morally speaking). ]
[Question] [ For my setting, I really want to push the non-human aspect of the other typical fantasy races. For Elves, I've been throwing the idea around that they go through a metamorphosis of sorts. I was thinking that they would look passable as a human to about age 15-20, then go through their metamorphosis. They would gain the typical appearance of an elf in my setting, ie tall, lanky body, sharper features, larger and pointed ears, etc. This would obviously be very painful, so I was thinking during this metamorphosis, they could gain a leather-like "covering" that grows over certain areas of the body, such as neck, belly, top of arms, etc as protection, which would dry out afterwards into a birchbark-like material that can be torn off. The covering could grow to roughly appear like surfaces near to them, such as bark, dirt, etc. Why would Elves go through this at all? I played with the idea of them being a race that replaces human children with their children (or that sends Elven children to live with humans), but I don't think that would work for my setting because I want Elves to have a central society that does raise their own children. I should note that in my setting, Elves are magical creatures, so it doesn't necessarily require all answers to be 1000% grounded in realism. [Answer] # Elves are human If you look at their DNA, they've got all the same DNA as a regular human. The transformation is purely magical, much in the same way that a vampire is someone who was born as a regular human and then was transformed. The metamorphosis is triggered by magic - either a spell is cast, and/or some potions are drank, and then a second, magical puberty hits you. Elvish societies are communities in which everyone goes through this process, but that doesn't mean that an outsider couldn't go through it too. Likewise, a child of elves could forego the process and just remain a regular human. By the way, this mostly happens at around 15-20 years of age because once you become an elf you stop aging, but any aging you've had prior is not reversed. You could do it at an older age but nobody appreciates an elf with an old appearance. [Answer] # Why does anything do a metamorphosis? To answer your question, the metamorphosis is useful to thrive or at least survive in a certain environment. That is already basis enough for metamorphosis. Metamorphosis comes in many sizes. Butterflies are well known for it, but it can come in a grrat many forms that can suit your needs! I've seen a documentary where a fish was in a pond. It'll stay a fish all its life. From being born, to reproduction to death. However, it can go into metamorphosis and change into an amphibious creature. It does this when the pond gets small and there's little room with all the other fish. This is because the ponds can experience drought. It'll evolve to a land creature as it prepares for the ponds to be unlivable. It'll lay eggs in that form, which will hatch when the ponds are back. Conditional metamorphosis or reversing the process happens a lot. In jurassic park they mention real frogs that can change their sex if too little of the other sex are present. Ants can evolve into buff soldiers. Jelly fish are apparently a symbiotic lifeform that can disband and live individually if required. Metamorphosis can be incredibly flexible. Your elves can do the same. They look like humans until conditions trigger a change. Age, proximity to other elves or a hundred small things can trigger it. You can set this to your needs. The reason for your metamorphosis is then a simple explanation. As an example, the human form can be more economical in many cases, while the metamorphosis to an elf gives a stronger, better lifeform, but requiring a higher abundance of food. So the metamorphosis would only trigger at a time of percieved abundance for the elf. After metamorphosis it has a much better chance to procreate. Metamorphosis is also not required for procreation. [Answer] When snake’s body grows, its skin does not. A larger skin layer is generated, and the old layer is discarded. Also shedding of the skin removes harmful parasites. **Growth of body** Maybe when elves grow, some parts of their body do not grow and they need a sort of metamorphism. **Defective skin** Older skin or some other parts of body have so many bacteria or defects that they must be removed. [Answer] **Super Grandparents.** The adaption allows a small number of people in each tribe to live an extended time. The rest of the tribe benefits from the wisdom that comes with age. This is a stronger version of how humans can be genetically useful to expanding the tribe even after they hit menopause. Note the transformation changes them mentally to better make use of their immortal body, and continue to learn with age, and not just become a thousand-year racist. The downside is increased food requirements, and a slower breeding rate. Or you can take it to the extreme and say *mature* elves cannot reproduce at all. In the pre-industrial era most Elves never metamorphose, since it is genetically a bad idea to have really long generations. Most tribes have only one or two *true Elves* who remove themselves from the genetic rat-race directly to better the chances of their relations. [Answer] **Humans undergo metaphorphoses.** I am thinking of my friend Zak, whose shall remain unnamed in the interest of privacy. He was sort of a pudgy little kid and then underwent a metamorphosis to become a hulking brute. It was painful; he got stretch marks, and then played football which was also sometimes painful. Later in life he has undergone a second metamorphosis. He has developed a > > "covering" that grows over certain areas of the body, such as neck, > belly, top of arms > > > although it is not so much leathery as squishy. This new covering is protective in that he is protected against starvation. Hair has disappeared from his head but reemerged at dozens of random spots over his entire body surface. From time to time he too > > appear like surfaces near to them, such as bark, dirt, etc. > > > although this is usually dirt, and it does not just appear, but is there because it was near to him, then on him, and the showers don't happen as often these days. This second metamorphosis is also physically painful because of the lumbago. So yes: metamorphosis is a thing, and what you propose for your elves does not seem so extreme. -- I like the idea of your elves leaving babies for humans to raise. Cuckoo bird style. Those elves make more babies than they really care to have around and farming some out to the humans just makes sense. They are really cute as kids before that first metamorphosis and they usually are out of the house by them. ]
[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/220431/edit). Closed 2 years ago. [Improve this question](/posts/220431/edit) I’ve been developing a world in which humans have disappeared, and pedigree dogs have returned to their country of origin. The story is set in the UK, roughly 3 years after the event. My idea was that religion is beginning to form within packs, with different ideas competing. My question was, what adaptions might have to be made for a canine religion? What ideas might they have that humans couldn’t? [Answer] Seems to me, in just three years, dogs might naturally regard the humans that used to care for them as Gods. Humans tend to create gods that resemble humans; dogs might have gods that resemble humans too. With magical powers; like producing food and water at will; sheltering dogs from storms, etc. **If** you are a good boy or a good girl. The religion might include hygiene, you don't eliminate where you live, you wait until you can get outside. Maybe, like saviors, they believe the humans will come back. Or perhaps they believe that when they die, they go back to live with kind human masters that provide love and everything they need. For a lot of dogs, including the one sleeping on my foot right now, their current circumstances may constitute dog heaven. [Answer] The idea of humans being gods is good, but I think a lot will also depend on how/why humans disappeared and what the dogs know about it. I mean, it's a very different story if humans died (and their bodies were laying around being eaten by cats) than if they just vanished one day. You also have to figure that there would be a tremendous die-off of dogs, especially pedigree dogs. All those "super cute" cosmetic breeds that humans have developed almost certainly died out pretty fast. The circumstances around the human disappearance will have an impact on how it is understood and remembered by the dogs. On a related note, depending on how people disappeared and what happened immediately after that, you might lose most dogs who know anything about people. I mean, most dogs that live with people live inside, and if there are suddenly no people to open the door, those dogs might never make it out of the house. That could mean that human worship is a sort of fringe religion among the few survivors who actually did live with people. That would be a great source of conflict if you paint the house dogs as a fanatic sect largely discredited or possibly feared by the rest of the dogs. What you could also do, if you want human-worship to be more wide-spread, is to make those few surviving house dogs almost oracles. Obviously, in a post-human world, many of our inventions and contraptions are still around, and after only three years, most of them would still be in play. Things like grocery stores might still be mostly intact (again, depending on the nature of the human disappearance), so dogs who have been into those stores with people in the past might know how to get inside, or where to find food in them. Maybe dogs who used to live in houses know that food comes in cans, even though you can't smell it. Service dogs would know how to open all kinds of doors too, and flip switches and do all kinds of "magic" things with these human artifacts. If you don't want dog religion to be that human-centric, dog religion would probably reflect human religions in many ways. For example, their deities would likely be canine. Just as humans had the fey, dogs might view wild canines like wolves and foxes as semi-divine creatures. Because dogs are pack animals generally living in family groups, they are well-suited to a familial pantheon featuring different gods in different roles. For example, the father deity who protects and punishes, the mother deity who cares and provides, the sibling deities who get up to mischief and create many of the stories and legends that will be told. Only three years after humans, this kind of established religion would probably have to have come from wolves or coyotes or something. What might be interesting to look at would be different pantheons for different breeds. Generally, people have gods that look like them, whatever that means to them. It might be just have a human shape, or it might have the same skin color, or it might have the same oblong heads, but people usually make their gods look like them (there are, of course, exceptions). With so many sizes and styles of dog, whether or not you choose to go with a human-centric religion or not, there is fertile ground for breedism. For example, if humans are gods, surely the Pomeranian is more divine than the husky because humans put so much more effort into Pomeranians. That also means that the dogs who would be most devoted to the Divine Human sect are likely also dogs who have the most to gain from it. After all, a pedigree dog could claim superiority through breeding while a former stray might rebel against a faith that makes them second-class citizens. Alternatively, if you broadly adopt a wolf religion that has nothing to do with humans, human-altered breeds would either be no different or would be scorned. Whatever you decide, remember that religion is a practical concern. It serves a purpose, often an emotional one, and creates a sense of understanding of the world and the practitioner's place in it. If a pack lives in an area with severe weather, their gods are likely to be temperamental and strict. If they live in a fertile and safe area, their gods are likely to be generous and kindly. The issues that the pack faces will determine what they need from their religion, and so will change what they believe and how they practice or express it. [Answer] The priest held up his paw for silence. "Hear me, for on this, the third anniversary of the Change, I bring you the truth. The Furry Mother herself appeared to me in a dream last night and gave me a vision. She revealed to me why the humans were taken away. All have sinned, even I. Our Furry Mother forgives us, because She is a loving mother. All she asks is for us to repent and try to do better. But there is one sin that isn't easy to forgive. Two groups among her creations kept creating false religions. One group was the humans. She permitted this, since she created humans to be foolish creatures, existing only to serve. Their silly views amused her. And sitting before me are so many members of the group that refused to discard their blaphemy, even after the humans were removed. Humans are not gods! They did not create the world. Our Furry Mother created them last and then took them all away without even twitching one of Her whiskers. Dogs must learn their place. Even though you are not cats, the Furry Mother loves you. She is ready to forgive you, but until you give up your sins, you are all just bad dogs.” [Answer] (amadeus excuse me, we seem to have found about the same answer within minutes..) Humans have disappeared, the dogs won't know why that happened. The religion of the dogs could have something to do with that. They'll miss us. For dogs, there will be a mythical past, where humans took care of them and gave them a purpose in life. In exchange, dogs had to be obedient. The religion will idealize this obedience.. and same time blame disobedient dogs for the disappearance of the humans. They sinned. The dog priests will sanctify the human period as the "time of the Gods". [Answer] As far as what dog religion can have that human religion can't I recommend incorporating smell. Dogs communicate in part by smell and can use smell to discern all kinds of important information such as where another dog has been, their health what they have eaten, as well as tracking. A scent of divinity or of evil would be interesting. Smell would almost certainly be used to define places of worship in much the same way we use color and sound. As for adaptations... there's a lot. The most important question is how dog-like are your dogs? Are they essentially humans in a dog's body? If so why didn't they already have religons? The most common religions today took multiple generations to form as history turns into legend. 3 years even for a dog is only a generation so if we assume dogs didn't have religion before the changing, the events of the changing wouldn't yet form a cohesive mythology, that's not to say a religion can't form just that it would be more like a cult or set of useful superstitions. A bigger problem is communication. As far as I have read, dogs can communicate their current state, but I haven't seen any ways to describe the past, different settings, instructions, or abstract ideas. Even if you made dogs smart enough to develop religions how would they communicate? Do they already have a language to boot? There's a decent chance secular leaders will also be religious leaders. Leaders would likely either have survival skills for natural enviornments(like hunting dogs or feral dogs) or man made enviornments (guide dogs or once again feral dogs). A guide dog may be more likely to profess a human centric religon vs a feral dog. Dogs aren't dominate in the ways humans are so they would likely see animals such as cats and wolves as moral agents which would be interesting to see ]
[Question] [ They're built in such a way that they can stalk and chase their prey on all fours like a feline can, and then easily return to digitigrade twoleggedness for everything else in their life (this is a species of alien people, not animals). They are over 6ft tall normally when bipedal. Maybe you can convince me that they don't need to get on all fours to hunt prey, but that's a question for another day. If it makes a difference about their eyesight, their planet is tidally-locked with a red dwarf star. [Answer] # Forward-facing eyes with round pupils, probably not much bigger than a human's, if at all. Your creatures are predators that seemingly rely a fair bit on vision, therefore, the best configuration relative to the skull would be a more forward facing one, as it allows a wider range of binocular vision, making them better at perceiving depth. As for the pupil shape, let's look at a very useful chart: [![enter image description here](https://i.stack.imgur.com/0Zsl0.jpg)](https://i.stack.imgur.com/0Zsl0.jpg) AS explained in it, your creature's best pick seem to be round pupils, as, being a predator, they seem to live in conditions much like those of a human, bear or large feline, meaning that they would likely benefit most from the classic round pupils. Eye size is where things can get funky. For example: some eagles, despite having much smaller skulls, have eyes nearly as big as a human's, since they need their vision to be top notch, and the bigger your eyes, the more space for light-detecting cells you have (for example: in the modern day T-rexes are assumed to having had pretty powerful eyesight, especially since they had eyes about the size of an orange). If your creature relies mostly on its vision, it might have eyes bigger than an average 6f tall human's, but if it relies more on smell, hearing or both, then human sized might be more than enough (especially if their eyes are more anatomically similar to a bird of prey's, as that'd mean they'd have no problem spotting things from afar, be it their prey from over a mile away or [an ant from the top of a 10-story building](https://www.livescience.com/18658-humans-eagle-vision.html)). [Answer] The largest terrestrial predators are big cats, bears, wolves, and humans. (And, I suppose, other large primates.) Cats and humans are probably the best ambush predators from the group. So, eyes like humans or cats. More likely humans, since we're around 6 feet tall and bipedal, descended from semi-bipedal ancestry. [Answer] "Bipedal" and "predator" make me believe that the most optimal configuration of eyes for this creature is eyes on the front of its head, which can see further due to being further off the ground. Additionally, predators don't need to look to their sides. *They're* the threat - they don't need to look for threats, at least to the level of having eyes optimized for it. I'm thinking something like this: [![enter image description here](https://i.stack.imgur.com/5dx3s.jpg)](https://i.stack.imgur.com/5dx3s.jpg) [Answer] **Pupils** The [standard answer](https://www.universityofcalifornia.edu/news/hunter-or-prey-eyes-are-key) most biologists would give you is that the pupils would be vertical slits because this allows better judging of distances: > > Species with pupils that are vertical slits are more likely to be > ambush predators that are active both day and night. In contrast, > those with horizontally elongated pupils are extremely likely to be > plant-eating prey species with eyes on the sides of their heads. > Circular pupils were linked to “active foragers,” or animals that > chase down their prey. > > > There is a complication though. This benefit decreases as the height above the ground increases. An intuitive explanation for this is that vertical slits allow better focus in the horizontal direction at the cost of worse focus in the vertical direction. For prey of equal size, a larger animal needs to to look down more, which means that the vertical focus is more important. **Eye placement** Front facing eyes definitely fit your species since that helps judge distances: > > The remaining two cues [of distance], binocular disparity and blur, work together with vertically elongated pupils and front-facing eyes, the researchers said. > > > **Eye size** Things get a little complicated here. Leuckart’s Law states that the faster an animal runs, the larger its eyes need to be in order to avoid obstacles. Larger animals also need larger eyes for the same reason. Both of these effects where shown to be significant in [this](https://anatomypubs.onlinelibrary.wiley.com/doi/pdfdirect/10.1002/ar.22480) study, although weight was found to be a more accurate predictor. If your species can run about 25% slower or faster than humans, then their eye diameter should be about [18mm](https://www.wolframalpha.com/input/?i=0.672%20*%20log10%280.75%20*%2044%29%20%2B%200.240%20%3D%20log10%28x%29) to [26mm](https://www.wolframalpha.com/input/?i=0.672%20*%20log10%281.25%20*%2044%29%20%2B%200.240%20%3D%20log10%28x%29). If they are about 25% lighter or heaver than humans, then their eyes diameter should be about [24mm](https://www.wolframalpha.com/input/?i=0.191%20*%20log10%280.75%20*%20100%29%20%2B%201.018%20%3D%20log10%28x%29) to [26mm](https://www.wolframalpha.com/input/?i=0.191%20*%20log10%281.25%20*%20100%29%20%2B%201.018%20%3D%20log10%28x%29). Considering the human eye is [24mm](https://www.wolframalpha.com/input/?i=human%20eye%20size), this checks out. ]
[Question] [ Commissars (Soviet era-type political commissars) typically exist to keep an army loyal to the state and indoctrinate them to the singular party of an authority's state. But with an army already loyal, they aren't all that useful in that role. What could commissars do without this role? This is for an entirely mechanised force. The government isn't authoritarian and is a functional democracy, although the military has a lot more autonomy than in most nations, and it's difficult for the government to force them to do something regarding their internal organisation. The government still determines where the military actually goes and what it does. [Answer] * Many military forces have a [chaplain corps](https://en.wikipedia.org/wiki/Military_chaplain). They believe that the spiritual needs of the troops should be ministered by someone in uniform, yet somewhat apart from the usual chain of command. Your *commissars* could fill the same role in a secular capacity. Morale officer, career advisor, ... * The British in India used [political officers](https://en.wikipedia.org/wiki/Indian_Political_Department) as a liaison with local rulers. Today their role might be called [civil affairs](https://en.wikipedia.org/wiki/Civil_affairs#U.S._Military_Civil_Affairs). Your *commissars* could fill this rule, acting as a staff advisor to the unit commander for local political issues. [Answer] The PKK is an, as far as I know, all volunteer force. To my best knowledge they don't have comissars as such, however the fighters spend a lot of time reading and learning theory - one german Journalist who spent some time with them recounts how two young fighters with not much formal schooling gave him an impressive and impromptu lecture on Öcalans take on ancient history and the history of their organization. Another thing the PKK does is organized, constructive, self criticism - the term is tekmil. Again, AFAIK without appointed comissars. But in your fictional army, these could be the roles of comissars: * organize political training of the soldiers * keep an eye on the group dynamics and mental wellbeing of the fighters (in accord with the military goals of the army) - what a chaplain might do in a conventional army, screen fighters that might need a serious shrink [Answer] The position of commissar could be a holdover from when the military wasn't completely loyal and so now the modern commissars' roles involve very little with maintaining loyalty as the role has expanded to included other things for the wellbeing of the military. [Answer] ## JAG Corps At their core, political commissars are simply people responsible for making sure that military leaders are following the core values of a nation. In totalitarian states, the core values are what ever idea the dictator just had that morning, but in a functional democracy, the core values are defined by the constitution and laws. So, the [Judge Advocates](https://en.wikipedia.org/wiki/Judge_Advocate_General%27s_Corps) you see in the US military are pretty much what you are asking about. Judge Advocates are often attached to high ranking military leaders, command centers, and programs to make sure that the orders being given do not violate Constitutional Law, Military Law, International Treaties, etc. and to server as advisors to military leaders to make sure that decisions are being made according to the most applicable laws. They also have the authority to remove and punish military leaders through the process of Court Marshaling. Even General/Admirals can be Court Marshaled. So, while a JA may not need to approve an order the way that a PC does, they can effectively remove any leader who is giving orders that do not agree with the law making sure that only leaders loyal to the Government's Laws can stay in power. [Answer] In a non-authoritarian functioning democracy, it isn't very likely that the average soldier (or sailor, marine, airman, spaceman, whatever) will decide loyalty to their commanders is more important than loyalty to the state (people). But it's very easy for an individual to become convinced that the civilian leaders have betrayed the people and have become a domestic enemy. A subset of the population in any democracy will almost always believe this; but if it becomes widespread and entrenched in an autonomous military that can effectively resist civilian control on matters it considers important, a coup will be a much easier step. A civilian government may want to guard against this possibility by embedding political commissars within the military. Commissars can provide political education to combat the idea that democratically elected leaders are not representing the people. They can also serve as monitors and early warning. If provided with training in individual and group psychology, they can identify unstable individuals and report any potential growth of antidemocratic ideology. [Answer] Single events can shatter people convictions in the most unexpected moments and in the most unexpected ways. Especially in a war where they are put under pressure so the functions of a commissar would be: * Ensure that they do what they are ordered to do even if it is highly immoral * Counter the enemy propaganda * Check that their loyalty is not only toward the nation, but also toward the right faction [Answer] # They do the training in the Crapsack World Army While the troops are 100% loyal, they are also poorly trained people that joined the military on their own accord to get away from their homes in an overpopulated metropolis. The commissar is less to ensure loyalty, he's there to improve the morale by keeping a careful eye on those elements that don't follow the rules perfectly or - even worse - don't follow an order. Those elements are not only pointed out to them by the really loyal troops but they are also made examples: in peacetime, they get the worst duties and if too bad ordered beaten to death by their comrades, in war, they get executed on the spot. Once the recruits leave their training units, they have been made the perfectly loyal and effective soldiers... made loyal by the commissar's rigorous training. Other countries might call them Drill Sargents, but those wish they could execute those failures to society - and Drill Sargents don't take their units in training to the frontlines! Other duties of the commissar corps are to investigate possible cases of low morale or disloyalty - and of course, lead such units into battle. ]
[Question] [ Would animals like camels and horses be more useful/practical in the deep desert than vehicles like dune buggies and sandrails? Basically, I have a planet that's mostly desert surrounded with rock formations and steppes. The deeper you go into the desert, the higher the dunes are, with the deepest places having straight up walls of sand that travellers have to go around. 1000-foot-high sand mountains are not uncommon. The people there use sandrails/buggies to travel around the less steep, more inhabited areas; but in the deep desert where the dunes are highest and there is no water, would it be better to use a camel-like animal for transportation? I imagine it could carry more supplies than the small sand buggies, and you could line a bunch of them up together to make a caravan. They could also navigate the terrain more easily. All this assuming travel speed/time isn't a problem, of course. The people's technology level in regards to vehicles is similar to ours. [Answer] Both have advantages and disadvantages: Fuel and spare parts are both bottlenecks on the practicality of vehicle operation in the deep desert. If those are readily available then vehicles, if they can handle the terrain, have certain advantages over animals, mainly in terms of how much materiel a single vehicle can move compared to a single camel/horse. Conversely if your one vehicle dies far from assistance all your stuff is there until help can reach you. Water and fodder are the corresponding bottlenecks for animal traction, you need water anyway so you *have* to carry a large amount of it, here there is a large divergence between your animals, camels are called "ships of the desert" for a reason, a camel can go for extended periods without food and water without dying and they can smell water from miles away (a fact that has saved many a desert traveler). Horses or pack mules on the other hand need to be feed and watered every day or they keel over. Camel trains carry less per handler than a heavy vehicle but probably more than a light one that is built for the deep desert, also because those supplies are broken up the death of a single animal need not be a total disaster. If you're not overly sentimental about your animals there are other advantages to a camel train. You can load it in such a way that you can cut animals loose when you have exhausted the supplies they were individually carrying. They can also constitute a reasonable portion of your supplies in and of themselves, a camel is made of meat, once a camel A's load is exhausted and you've made a reasonable start on camel B's pack slaughter camel A and add it to the load. Better yet if you have water reclamation technology that can purify the water content of the animals' blood and digestive system. [Answer] You may well find the choice of vehicle vs pack animal answer is dictated by; A) the specific terrain features you have to cross; and B) the distances that a particular caravan (or even single traveler) intends to cover; Or if you prefer simple economics. In the case of terrain you've mentioned rock formations and steppes. If the terrain your traveling through is mostly going to be dominated by stretches of rocky slope or bolder strewn steppe that a heavily laden wheeled vehicle might struggle with then pack animals might be your preferred option even if that makes the trip slower. Mostly or all sand dunes? The reverse would apply. The distance issue? If your hauling lots of passengers or cargo over long distances vehicles would probably be more economical because you'd have economies of scale and speed on your side. If on the other hand all your doing is transporting small loads out from a local population center/transport hub to small local villages that surround it and any one trip is only going to take a couple of days or so maybe pack animals would be simpler and more economic. There's no reason it would have to be one or the other **unless the place was reasonable well industrialized** when vehicles would always win out. [Answer] If there is no water, you will have to carry water for them and also fodder. The advantages of animals over machinery would be more on the order of not needing factories to make them or repair parts. [Answer] **Productivity** Vehicles need fuel, animals need water and fodder. However, with the right amount of fuel vehicles can provide a lot more work. In our society animals were displaced because we had enough productivity and enough fuel to set up factories to build the vehicles and a production distribution network to process crude oil and other resources into fuel, we also have extra population to dedicate to the production of spare parts and maintenance. If a planet is sparsely populated then, letting the animals to breed and grow by themselves might be more efficient than devoting part of the population to the factories, the fuel production and the maintenance. **No oil** If the planet was recently terraformed or has always been a desert then there would not be oil. It was life that produced and accumulated over the ages the most practical energy form we have today. New technologies might find a replacement for oil, but it could be more expensive tilting the balance in productivity. ]
[Question] [ So I have a rather large late medieval feudalistic empire that is roughly about the size of South America top to bottom in terms of its radius. Road networks are typically well-maintained between major cities due to their strategic importance. Legally, the vast majority of the human population are considered subjects of whatever noble rules where they were born and can only leave said noble’s lands with permission. While many do, they are legally required to return to the land of their birth if there is ever a change in leadership (normally due to death). Assuming news of such important events are spread by messengers on horseback on a well-established relay system rather quickly, how long will it take a slow moving merchant on a horse drawn cart full of heavy goods who needs to stop for market day every weekend to return to their noble's realm in the most extreme cases? [Answer] # Years Using the same assumptions that @Tom did in their answer, but using [this example](https://www.medievalists.net/2019/08/travel-middle-ages-road/) of medieval travel, we have this nugget for a fully loaded wagon: > > Trundling along with carts, particularly ones laden with trade goods, might slow down the travelling party. For example, when Margaret, newly minted Duchess of Brabant, decided to move her entire clothing collection to her marital home in 1297, it took the cart eighteen days to travel the first 85 or so miles, from London to Ipswich. (And it took five horses to move the cart even that “speed.”) > > > That approximates 8km a *day*. Assuming an as-the-crow-flies 5000km trip, without stopping for market days, that's 625 days' travel. If we assume market days, that becomes 715 days' travel. And all of this assumes that the roads are fine in all seasons. A winter storm might stop the merchant for weeks, unless he can change his wheels for skids. A summer storm might wash out a road, making it completely impassible and requiring the merchant to backtrack and find another route. All of this also assumes that the merchant wants to/is impelled to make the trip with as much haste as he can manage while still bringing his wares along. A roundabout route (which will be required anyway, as I doubt there's a straight-as-an-arrow road the length of the empire) with regular stops beyond market day could result in the merchant arriving half a decade or more after receiving notice. Edit: Additional potential complications * Sickness (merchant or horse) * Bandits (he's travelling with goods, and presumably without escort) * Wagon breakdowns (common on a long journey) * local conflict * ... and so on. If we're assuming the "most extreme case", as indicated in the question, it might be the merchant's kids who arrive, rather than the merchant who initially set out. [Answer] ***My estimate when all goes well: 110-140 weeks, that is roundabout 2.5 years*** Opening: *"a slow moving merchant on a horse drawn cart full of heavy goods who needs to stop for market day every weekend"* I'll base my calculations on the fact our merchant will do a weekly stop. This makes it convenient, to calculate the time span in weeks, using week travel distance as a starting point. **Going straight and 24/7 with one weekday off: 61 weeks** Given our merchant will visit a market to buy and sell goods every week, *ideal* distance between the villages encountered would be one week travel. According to the [other topic](https://worldbuilding.stackexchange.com/questions/67455/travel-time-in-medieval-times) a week's travel in medieval times would be about 90-100km max, on foot. Our merchant owns a horse, but his cart is heavy loaded, so it will not allow for much more than that. Assuming one day of market pause per week, let's take 82km/week, travel 61 weeks, that is just over 14 months over 5000km with no unfriendly encounters, no mountains or other obstacles, sunshine 24/7, over perfect roads, all villages aligned straight toward the target, 82km distance between them. A non-existent world. **Travelling salesman over randomly spread villages 90-120 weekly stops** Medieval villages will not be on a square grid, let alone be evenly spread. The weekly travel distance (82km) sets the *max step* travel distance in a travelling salesman map. A travelling salesman simulation will never go straight in one direction, or travel a perfect 82km between villages. In order to avoid direction issues at certain points reached, I used an *average* distance of about 40km between villages, which is roundabout realistic for European villages having their own market. I found searching for 40-82km week travel distance and setting a target of travel 5000 km away will yield 90-120 market stops, depending on the random map initially generated. One province to travel north-south could look like this, [![enter image description here](https://i.stack.imgur.com/TfC2L.png)](https://i.stack.imgur.com/TfC2L.png) Note here: using any algorithm to predict human behaviour is risky. Our merchant does not even have a map, he can look at the sun and stars, to determine direction. A medieval merchant will definitely not understand the concept of optimal paths. So this 90-120 weeks assumes the merchant will have a map with my directions ! **Winter seasons will cost 20 weeks** In a time period of 90-120 weeks, our merchant would have to stay put during winter season, you can't travel a heavly loaded cart through snow on a medieval road. Say each winter season would require a stop of 10 weeks, travel time will become 110-140 weeks. BUT.. One pitfall exists, with the above question.. you ask for "in the most extreme case". That would make a calculation useless - the merchant could die of illnes, or in a robbery - or at least *indeterminate*, because we don't know anything about the landscape, or the circumstances of travel. Encountering deserts, lakes, rivers and mountain ranges could involve detours, to reach a passage. Also, bad weather could occur outside winter season. A flood would be devastating for the merchandise ! Having lost all, the merchant would be required to work on farmlands during harvest period, in exchange for food and new goods the farmer provides. The merchant's cart can be broken and require repairs.. In medieval times, a traveler could get stuck in a nearby village for weeks, to replace a wheel. Road blocks like fallen trees could be unsurpassable, resulting in having to *travel back* to the previous market village and start over, in some sub-optimal direction, on shorter distance. A nice reference on the topic: <https://mythicscribes.com/history/wagons-carts-trucks/> [Answer] # ~73 days First, some basic inputs: * How far is the merchant traveling? > > roughly about the size of South America top to bottom in terms of its radius > > > I came up with a figure of about 5000 km in diameter, judging by google maps. > > in the most extreme cases > > > The most extreme case would be: from one end to the other. So, the full 5000 km. * How fast does a merchant wagon travel? > > A stagecoach traveled at an average speed of about 5 miles per hour (8.0 km/h), with the average daily mileage covered being around 60 to 70 miles (97 to 113 km). [source](https://answers-about-horses.com/index-https.html) > > > Furthermore, you said "a slow moving merchant on a horse drawn cart full of heavy goods," so let's take the low end and say the wagon covers 80 km per day of travel. * How many travel days are there? You also said, "who needs to stop for market day every weekend." So, 6 days per week are spent traveling. I'm going to assume the seventh day is spent hawking wares *and also* taking on supplies (e.g. feed for horses). ## Now let's crunch some numbers How many travel days does it take to cover 5000 km at 80 km per day? `5000 / 80 = 62.5` (Let's round up to 63 days.) How many market days are there in a 63-day period? `63 / 7 = 9` So, that's 9 extra days that must be spent traveling (which adds another market day, since 9 > 7). `63 + 10 = 73` None of this takes into account difficult terrain or bad weather. If the merchant is making the trip in the winter, or during a rainy season, it will be slower (possibly very much slower). If there are big mountains to go around or over, it will also be slower. If there are big mountains that must be climbed over *in the winter*, the merchant may be forced to wait weeks or months for the season to change. # The news It may be worth noting that the news of the lord's death would not be spread primarily by slow-moving merchant wagons. It would likely be spread by swift messenger, or by messenger creatures, or even by remote signalling. So, it's likely that the merchant would not arrive back in the lord's domain until the lord had been dead for at least three months. (I'm spitballing, based on the assumption that the messenger will move faster, and won't stop one day per week.) [Answer] We have some comparable historic data to use: the US westward migrations in the middle of the 19th century. For instance, a bit of searching shows that the Oregon Trail had a length of ~2170 miles/3492 km\* <https://en.wikipedia.org/wiki/Oregon_Trail> It took 4-6 months for pioneers carrying their goods in wagons to travel that distance. Those wagons were often drawn by oxen rather than horses, and the trail was in no sense an improved road, so this should be taken as reasonable estimate of the upper bound for travel time with horses on better roads. \*Approximate because there was no single start or end point. [Answer] A medieval empire the size of South America would be vast. The area of South America is about 17,840,000 km2 (6,890,000 sq mi). According to Wikipedia, the only empires in history larger than that would be the British Empire, the Mongol Empire, and the Russian Empire. [https://en.wikipedia.org/wiki/List\_of\_largest\_empires[1]](https://en.wikipedia.org/wiki/List_of_largest_empires%5B1%5D) It would probably also contain large bodies of water which would have different rates to sail across than to travel the same distance on land. And your ideas about the organization of such a vast medieval empire seem rather simplistic. > > Legally, the vast majority of the human population are considered subjects of whatever noble rules where they were born and can only leave said noble’s lands with permission. > > > Legally, the entire population of the Empire will be subjects of the emperor. And if the empire has feudal lordships, the natives of a fuedal lordship will be subjects of their feudal lord, as well as subjects of the emperor. But remember, in feudal Europe, most feudal lords of manors were vassals of the local count, and most counts were the vassals of their local dukes and all Dukes were vassals of the king - if they weren't vassals of the king, they were outside his kingdom. So in a feudal empire, you might suppose that the average peasant was the subject of: 1. his local lord. 2. his count. 3. his duke. 4. his king. And: 5. The Emperor. But that is an oversimplified hierarchy considering the vast size of the empire in your story. According to the Wikipedia list, the Mughal empire around 1700 had only about 4,000,000 square kiometers of land area, only about 0.224 of the aea of South America. And most of the empire consisted of provinces administered by appointed governors. So you wouldn't think there was much room for vassal kings, and vassals higher than kings. But there were a number of vassal state within the Mughal Empire, just as there were within the British Raj of India. The Mughal Padishahs grant a number of titles to their Hindu subjects and vassals, including many which were more or less noble ranks. The lowest royal title granted by the Mughals was *raja*, king, and the ranks of royalty went up from there. > > Raja - king. > > > Raja Bahadur - illustrious king. > > > > > Maharaja - great king. > > > > > Maharaja Bahadur - illustrious great king. > > > > > Sawal Maharaja Bahadur - elevated illustrious great king. > > > > > Rajadhiraja - king of kings. > > > > > Rajadhiraja Bahadur - illustrious king of kings. > > > Maharajadhiraja - great king of kings or king of great kings. > > > > > Maharajadhiraja Bahadur - illustrious great king of kings or illustrious king of great kings. > > > My answer at [https://worldbuilding.stackexchange.com/questions/110223/imperial-kingdoms[2]](https://worldbuilding.stackexchange.com/questions/110223/imperial-kingdoms%5B2%5D) also includes examples of Kings of KIngs who were vassals of Roman Emperors. It also mentions that the High King of Medieval Ireland could be considered to be a king of kings of kings of kings. Your empire is so vast that the various vassal kings should not be subject only to kings of kings. The kings of kings need to be subject to Kings of kings of kings and so on up to the Emperor. And presumably the Emepror would also be the lord of many lordships, the count of many counties, the duke of many duchies, the king of many kingdoms, and king of kings and king of kings of kings, and so on, in order to have enough areas under his direct rule to maintain his authority over the other kings, kings of kings, kings of kings of kings, etc. in the empire. Or perhaps the imperial domain at the center of the empire would consist of a region the size of the Roman Empire, for example, directly administered by appointed officials at various levels, with tax collection to support a well trained and well equpped army of hundreds of thosuands of men, more powerfull that all the feudal levies of the vassal kings, kings of kings, kings of kings of kings, etc. combined. So an ordinary peasant in your empire might be the subject of many different levels of lords and kings up to the Emperor. And with that many levels of persons the peasant is a subject of, one of them would die and be succeeded about every other year. So you need to restrict the number of levels of lords that a person would be obligated to return home every time a new lord inherited. Otherwise your traveler would have to return to the headquarters place of some lord above him about every other year. And medieval European peasants had several different legal and social classes. Some peasants were slaves, the personal property of the lord of their manor, and could be bought and sold. Some peasants were serfs, who were legally tied to the manor, and whose relationship with their lard was a matter of the feudal customs, sometimes open to negotiation. Other peasants were free persons who rented lands owned by the lord of the manor and had more freedom to negotiate terms with him. And it was perfectly possible for peasants to be free persons owning their land, which would not be part of any manor, and so they were only subordinate to whoever had political and legal jurisdiction in their region. Many peasants did own their land. And medieval empires varied in how urbanized they were, but most had a number of towns and cities with populations who were not subject to any feudal lord. So what social class of person would be most likely to become a travelling merchant? A free resident of a town would be the most likely, And a younger son of a free land-owning peasant who wouldn't inherit his father's farm would be the next most likely, and so on down to least likely, a slave. Any sort of serf with many legal obligations to his lord would be the second least likely class of person to become a merchant. So you need to create a special (and very small if your society is like Medieval Europe) class of persons for your story, who are sort of slaves or serfs of a feudal lord, and have many obligations to that lord, but for some reason have permission to travel extensively, with an obligation to return periodically to account for their doings on their travels, and to return when the lord dies and swear allegiance to his heir, the new lord, and renew their permission to travel. And they should face legal penalities for failure to return within a specified time. Those might be civil penalties or criminal penalities for their relatives remaining at the manor. And your particular character may have family members at home who would face exceptionally harsh and severe punishment if your character failed to return in time, due to some very special circumstances such as a crime, punishable by death by torture, which a relative has been convicted of, with the punishment deferred as long as the traveller fulfills all his obligations including returning in time when required. Perhaps the character's role of a merchant is just a cover for some secret mission(s) he carries out for his lord, though he is free to make a profit from it if he can. [Answer] Someone asked a [similar question](https://worldbuilding.stackexchange.com/q/13/52038) years ago, I suspect you might find the answers useful. For efficient information dissemination, I assume a fast courier would bring the news to some sort of carrier pigeon aviary, where it would be copied, and then sent out on each carrier pigeon, where the news would then be sent out via couriers or town criers. ]
[Question] [ I have a question regarding worldbuilding and haven't found a question like this yet, so I created an account and hope that someone can answer it :D As a starting point, imagine our real-life Sun, Earth, and Moon. 1. Is it possible for the Moon to always be in Earth's shadow, to basically create a permanent Lunar eclipse? 2. Which Values (for example Earth-Moon-Distance, Moon's speed around the Earth, Moon's Mass, etc. (sorry for the non-scientific words, I'm not good at astronomy and physics)) would have to change for it to be possible? 3. If it is not possible for the actual Moon (or a Moon with different Values) to always be in Earth's shadow, would it be possible to have another Moon-like or Planet-like object that orbits the *Sun* to always be in Earth's shadow? 4. How big, small, dense, close earth could that other object be to be stable in Earth's shadow? **EDIT**: As I understand the answers so far, basically my idea would not be possible in the real world. I know this forum is not really for discussions, but I had another idea: What about, instead of a circular Moon orbit with Earth at the center, an oval-ish Moon orbit that has its center somewhere in Earth's shadow.... something like: (SUN)--------(Moon)-(Earth)-----(Moon) Oh dear, I hope you can understand what I mean, it's not to scale of course. My new question is basically, would a Moon orbit be possible where the moon is like more than 90% (maybe even like 99%) of the time "behind" the Earth? I guess there would be a lot of implications, tides come to my mind and I am sure you smarter people can think of a lot more implications... but the basic question stands if it would be at all possible. If that is not possible as well, then I guess I will have to give the Moon some kind of thrust, that seems to be the only way to give it a stable "orbit" in Earth's shadow, if I understand the answers correctly. [Answer] It is not possible for an object to be in the shadow of Earth permanently - although it could be in the semi-shadow called penumbra, the full shadow (umbra) does not extend that far. There is a special place called the [L2 Lagrange point](https://en.wikipedia.org/wiki/Lagrange_point#Lagrange_points) that allows an object to orbit around the Earth at about the same rate as the Earth orbits around the Sun - thus always remaining in the same relative place in terms of shadow. However, L2 is not a super stable point to orbit in, and thus objects tend to fall away. This is not a problem for artificial satellites, though, and the [James Webb Space Telescope](https://en.wikipedia.org/wiki/James_Webb_Space_Telescope), when launched, will take advantage of this constant half-shadow to make better celestial observations. So: 1. Yes, it is possible, although unlikely. This "moon" is more like the Death Star, and will need some kind of course correction to stay in orbit. This could potentially be "explained" by matching the moon diameter and the umbra diameter, meaning if it started to move out of position the sun would warm part of the surface, leading to off-gassing pushing the moon back into place. Probably not 100% scientifically valid, but otherwise this needs to be a spaceship, not a moon. 2. To calculate the L2 point: $$d\_{Earth-L2} = d\_{Earth-Sun}\sqrt[3]{\frac {M\_{Earth}}{3M\_{Sun}}}$$ Where $d$ is respective distance, and $M$ is the respective mass. Note the **cube root**. To calculate the Umbra Diameter at the L2 point: * First calculate the umbral distance: $$d\_{umbra}= \frac{d\_{Earth-Sun}}{\frac{r\_{Sun}}{r\_{Earth}} - 1}$$ Where $r$ is the respective radius of the body. * Then, if the umbra distance is more than the L2 distance, you can calculate the size of the umbra (max size of your moon) with this equation: $$r\_{umbra}=\frac{r\_{Earth}}{\frac{d\_{umbra}}{d\_{umbra}-d\_{Earth-L2}} + 1}$$ For the non-mathematically-inclined, I combined this all into a [Google Spreadsheet](https://docs.google.com/spreadsheets/d/1xGE25qK_x9lgTbPESs768mBwuPKIECVwjM5HJM34Q1w/edit?usp=sharing), make a personal copy to edit. 3. So, the Lagrange point kind of orbits both. 4. Normal densities (3,000-8,000 kg/m^3) should work. Mass of the object at the L2 point does not matter significantly. However, some kind of automatic correction will be necessary. [Answer] **Not possible with current configuration** To have an object perpetually in the earth's shadow, it must circle the earth at the same rate that the earth circles the sun, in order to keep the earth between it and the sun. To have a satellite with an orbital period of 1 year, it needs to be very far from the earth, approximately 2.1 million kilometers away (according to [this orbital calculator)](https://www.satsig.net/orbit-research/orbit-height-and-speed.htm). Unfortunately, that distance is outside the Hill Sphere of the earth, which is the region in which the force of the earth's gravity is the dominant force. At a distance of 2.1 million km, an object is simply not orbiting the earth anymore. Even if it was, the earth's umbra (region of total shadow) only extends 1.4 million kilometers, so an object at such a distance would never see the sun completely occluded by the earth. You could put an object at the L2 Lagrange point, which would allow the object to orbit the sun with the same period as the earth, even though it has a greater orbital altitude than the earth. Unfortunately, the L2 point is unstable, and it exists at about 1.5 million km away from the earth - too far for the earth's umbra to reach. Even if you could get an object to stay at the L2 point, it would never be in complete shadow from the earth. I'm not sure how you could achieve such a configuration by modifying the solar system. If you increased the mass of the sun significantly, you could shorten the earth's year while staying at the same distance from the sun, which would in turn allow the eclipsed satellite to also have a shorter period and a lower orbital altitude, although the Hill sphere of the earth gets smaller as the sun's gravity increases, so the math might not work out. [Answer] What you're trying to do is maintain a satellite in Earth's shadow while it travels around the Sun. You can't have the satellite orbiting the Sun with the same orbital period as Earth and not be *in Earth's orbit*. (Unless you're at L2 [or any other L-point, but only L2 is "behind" Earth], which is *just* barely [outside Earth's umbra](https://astronomy.stackexchange.com/q/13585/26216) and unstable in the long-term anyway.) The only solution I can see is that the satellite needs to be on a powered trajectory, perhaps a circular orbit "behind" Earth, in between Earth and L2 and within Earth's umbra. Such an orbit can't exist naturally and would need constant thrust to maintain. If the Object is alien in origin, this can probably just be handwaved away. [Answer] I think other answers are on the money, but we can play with the values a bit to make it work. So the Earth's umbra falls just short of an object at the Sun-Earth L2 point. Now what if the "moon" is the big object? you'll want to see it like a moon from Earth even though it'll be much farther away than the actual Moon. So the moon is a large planet, and the Earth is a smaller planet at the Sun-moon L1 point between the Sun and the moon. This is also an unstable configuration, but handwave that for now. You can make the Sun a smaller star and move the whole system closer together to keep Earth habitable, extend the umbra, and move the moon deeper into the umbra. Tada! The stability thing is still a problem, only the L4 and L5 points in these three body systems are stable (Jupiter has it's own pseudo asteroid belts in those spots called Trojans). However... you can probably just ignore that issue if it's problematic to the setting. It's not like Larry Niven's Ringworld is super-accurate from a physics perspective. [Answer] ## Cover it in corner reflectors Others have covered why a permanently eclipsed Moon is *hard*, requiring major changes to the Earth-Moon system. But the Moon could be in its *own* shadow if it returns all the light striking it to sender. I don't think I can post animation here, but the second image at the [Wikipedia article on corner reflectors](https://en.wikipedia.org/wiki/Corner_reflector) illustrates how that works. However you move the light beam, it strikes three perpendicular mirrors and goes back exactly the way it was sent. Think of markers on the road at night. ([We actually *have* a few corner reflectors on the Moon](https://www.sciencetimes.com/articles/26827/20200811/50-years-earth-receives-laser-signals-moon.htm) that send laser light back to astronomers so they can measure its precise distance. But not enough to change the color of the entire surface as of yet!) Such a moon might never reflect the Sun, or at least, only when it is nearly full if there is some imprecision (in which case it would be nearly as bright as the Sun for a bit). Most of the time, you would see a Moon the approximate shade of your own patch of Earth, dark at night, brighter during the day, always featureless and homogeneous. If the reflectors are precise enough, on Saint Patrick's Day zealous folks would try to get everyone in the city to display green lights until the Moon turned green. ]
[Question] [ I was reading the description of the Azer in D&D 5e. Part of their description is that they resemble a male dwarf. Another part of their description is that they are crafted from bronze and imbued with a part of the crafter's inner flame. My question is wider than for just the Azer, and could be applied to other "created" races such as AI Robots, or D&D warforged. **What constraints would there be to keep the general form of the offspring similar to the creator/parent?** I'm not asking about the Azer specifically, but an answer could use them or something similar to illustrate a point. For additional clarity, this is in reference to a race that reproduces itself by constructing them in some other manner than biologically bearing offspring, but the offspring are still very similar in form to the "parent(s)". [Answer] A number of possibilities: 1. Mass production and economies of scale. It's vastly more efficient to create identical copies of a single template or mold than to create lots of variations. In a magical setting this could be something like a creation spell; the spell is relatively accessible to use, but makes all the same copies, whereas creating a new spell to make a different variation is massively difficult. 2. Culture of conformity. Everyone *wants* their creation/offspring to look like the others. This could be because sticking out is looked down upon, or perhaps there's practical advantages to blending in with the crowd. 3. Convergent optimization. It's not that looking alike is intentional, but the beings are all created for the same purpose, and it so happens that there is an optimal appearance for that purpose that everyone independently converges on. [Answer] Simple explanation: the magic/programming/whatever they inherit from the "parent" tends to be specific to the form it's meant to control. To use an example, the "subroutine" used to move an two legs will not be the same as one used to move on four, or on wheels, as there are issues of balance and timing of motion that can be very different. If those subroutines are an inherent part of the base program, then it means they're not easy to simply swap out to deal with a very different body form. They might be able to deal with some variations (slight differences in limb length or body size, for example), but not radically different ones without a major change in the basic nature of the entity. [Answer] Part of the answer is in your question: "...imbued with a part of the crafter's *inner flame*." "Inner flame" is code for "soul". The "soul" doesn't work on a being that isn't like themselves. You can't put a human soul, or dwarf soul, into a dog, or a bird. And it doesn't work quite right when you go from human to dwarf either, even though they might be closer types of beings. The "soul" resists and the transfer falls apart. The best transfer is kind to kind (human to human, etc.). The second best is kind to your artificial offspring. Everything else doesn't quite work. And/OR, if you'd like to be even more specific, that specific "inner flame" can only go into that specific crafters artificial offspring. Len can only put his inner flame into the an artificial being that Len created (lol). So they cant create entire armies, but rather only offspring that are more like actual children. That could be an interesting limitation to explore. *Of course, this is all assuming we're talking magic and that the notion of "souls" or "inner fire" exist in your scenario.* ]
[Question] [ Let's assume that one day there is a substantial human colony on the Moon. Much later, the Moon becomes terraformed. I'm trying to imagine when and what humans would first be able to detect with hand-held telescopes or binoculars when viewing the Moon from Earth. Would they first see the lights of a large city on the night side of the Moon? Would they be able to see a city that is the equivalent of Tokyo, say? Would they not see anything until substantial terraforming had been done and the Moon became a 'blue planet' like Earth? How can we calculate the size and relative brightness of human construction that would enable the Earth-bound to actually see something distinguishable on the Moon's surface? **Assumptions** There would be plenty of media coverage of course, but I'm interested in what would be the very first signs that would be visible just by looking up on a clear night, possibly with the aid of an ordinary 21st century type aid such as a hand-held telescope or binoculars. Please ask for clarifications before answering. [Answer] ### You could see Tokyo on the moon with a cheap telescope. * So using a [cheap telescope I found on amazon](https://www.amazon.com.au/Celestron-21035-70mm-Travel-Scope/dp/B001TI9Y2M/ref=asc_df_B001TI9Y2M/?tag=googleshopmob-22&linkCode=df0&hvadid=341791604324&hvpos=&hvnetw=g&hvrand=7012307992637608187&hvpone=&hvptwo=&hvqmt=&hvdev=m&hvdvcmdl=&hvlocint=&hvlocphy=9070873&hvtargid=pla-343899256700&psc=1), one could get 40 times magnification. * The full moon is 1/2 a degree in the sky. Or 30 arc minutes. * The human eye can see about 28 arc seconds of resolution. * So your basically getting 62 "pixels" of moon for the naked eye in horizontal and vertical direction. * Your telescope will multiply this by 40 so ~2400 rows of pixels. * The moon has a diameter of 3400km, so your looking at a pixel for every 1500m ish. * Tokyo is 90x25km ish. So approximately 60x18 pixels. * You will not be able to make out individual buildings or roads, but the difference in Albedo between a city and lunar regolith is likely to be noticable. + Even if built out of regolith so the same colour and albedo, the surface normals will be structured rather than random resulting in different light levels in that area depending on the sun angle. * When the moon isnt full, the city will be very visible, as the city lights will leak and create a bright glow. [Answer] The first thing on the moon that could be visible from earth is already there. [A mirror.](https://science.nasa.gov/science-news/science-at-nasa/2004/21jul_llr/) > > Will anyone notice, 100 feet away, something else Armstrong left > behind? Ringed by footprints, sitting in the moondust, lies a 2-foot > wide panel studded with 100 mirrors pointing at Earth: the "lunar > laser ranging retroreflector array." Apollo 11 astronauts Buzz Aldrin > and Neil Armstrong put it there on July 21, 1969, about an hour before > the end of their final moonwalk. Thirty-five years later, it's the > only Apollo science experiment still running. > > > Although it can not be viewed by binoculars, it can be seen by telescopes if one times it right. But guaranteed, any large solar array would reflect light back to earth when the moon is in the correct position, and the flash would be easily seen by binoculars. But to actually SEE anything and recognize it, here is what the [Hubble telescope](https://skyandtelescope.org/observing/how-to-see-all-six-apollo-moon-landing-sites/) could see. > > Hubble's 94.5-inch mirror has a resolution of 0.024″ in ultraviolet > light, which translates to 141 feet (43 meters) at the Moon's > distance. In visible light, it's 0.05″, or closer to 300 feet. Given > that the largest piece of equipment left on the Moon after each > mission was the 17.9-foot-high by 14-foot-wide Lunar Module, you can > see the problem. > > > So if you are talking a human-made feature, 300 feet would be the minimum size for a very powerful telescope. If you want binoculars, then to see a covered dome over a hundred km. diameter crater, the minimum would be a good 40x or 50 x [binocular](https://binocularsguides.com/can-i-observe-moon-and-planets-with-binoculars/) would work. You are not going to see a typical lunar habitat, of course, or make out any detail - you will only be able to see that something is there. > > Magnification 40x, 50x Binoculars with magnification 40x and 50x are > very powerful and produced by such optical companies as Oberwerk, > Orion. > > > They are very expensive BTW. With such powerful optical instruments > you can see a big picture of the Moon and craters, even small ones. > > > But 90X is better > > Magnification 90x This powerful instrument with magnification 90x by > Oberwerk gives you a huge power and you can see unbelievable picture > of the Moon and craters. > > > But I would recommend [image stabilization binoculars](https://www.opticsden.com/the-best-image-stabilization-binoculars/). Of course, something like [this](https://www.telescope.com/Orion/Orion-GiantView-BT-100-ED-90-degree-Binocular-Telescope/rc/2160/p/132191.uts) Orion GiantView BT-100 ED 90-degree Binocular Telescope would give you a clear view of a domed crater, for sure. [![enter image description here](https://i.stack.imgur.com/FyFX8.png)](https://i.stack.imgur.com/FyFX8.png) > > Views of lunar craters to wispy nebulae will take on an almost 3D feel > in the GiantView BT-100 ED. The 100mm aperture objective lenses gather > 56% more light than 80mm binoculars, so you'll be able to see more > objects in the sky with greater clarity. > Blockquote > > > But let us go the reverse - [what can we see on Earth from the Moon?](https://www.lpi.usra.edu/meetings/LEA/whitepapers/Johnson_etal_v02.pdf) Seems to me that if we can see it in one direction, we could see it in the other direction. This article is about using remote sensing of the Earth from the Moon. > > The largest technical constraint to observing the Earth from a lunar > base is spatial resolution. At the sub-Moon point, the > diffraction-limited resolution (R) can be approximated (in km) by R = > λ/D where λ is the wavelength (in microns) and D is the telescope > diameter (in meters). At visible wavelengths a spatial resolution of 1 > km or less requires a 1 meter or larger telescope. Figure 2 shows this > relation for three telescope diameters. > Blockquote > > > The chart in this pdf demonstrates that a 0.1 m lens would have a resolution of 30 km of a wavelength of 3.0 microns and a resolution of 5 km. of a wavelength of 0.50 microns. So obviously we could not see an individual building, or even a city block, on the Earth from the Moon. Likewise, we could not reasonably see it in the other direction, either. But features bigger than a large city on Earth could be discerned from the Moon using a 100 cm. lens. Mind you, this is just discerning that it is there, not seeing any details about it. Like seeing a blob. Put in perspective, it is doubtful that a nuclear explosion on Earth would be more than a speck as seen from the Moon through very powerful binoculars. This article concludes by saying > > While the arguments for Earth observations from a lunar observatory > are intriguing, it is typically considered unlikely that the > advantages outweigh the challenges when viewed insularly. However, as > stated by [10], “a lunar astronomy program should complement the > earth-orbiting satellite program.” For example, one can easily imagine > simultaneous observations of the Earth from instrumentation on the > Moon and from geosynchronous Earth orbit (GEO) meteorological > satellites in order to provide radiometric crosscalibration between > instruments. > > > Let's take another approach. Can we see a meteor impact on the moon from Earth with the naked eye? Apparently, we can. [NASA has been looking carefully at the Moon](https://www.straightdope.com/21344208/if-a-big-meteorite-struck-the-moon-would-we-notice-it-here-on-earth) for meteorite impacts, and has logged some that could be seen by the naked eye, if you happened to be looking at just the right time, > > To get an idea of how nontrivial, NASA began counting visible strikes. > So far it’s tallied more than 300. The one on March 17 was the biggest > so far, ten times brighter than anything seen previously, although > nowhere near the hypothetical one-kilometer catastrophe you’re talking > about. This rock was more like a foot in diameter and weighed maybe 90 > pounds. > > > Still, it was traveling close to 56,000 miles per hour and had an > impact equivalent to five tons of TNT, gouging a crater perhaps 65 > feet across. NASA has asked the scientists operating the Lunar > Reconnaissance Orbiter, now mapping the moon’s surface, to take a > picture of the March 17 crater, and they expect to get around to it > later this year. > > > So an explosion of five tons of TNT would do it. That is some industrial accident. Or a very big mining operation. However, if you were looking at the moon with an infrared imaging device on your binoculars, you could most certainly see evidence of heat signatures from a reasonably large enough colony, say 5 km.in diameter or so. Seen as a pin-prick of light, perhaps. So apparently you will have to wait until the moon colony develops a substantial light pollution night time map, or a heat signature, of a major city before we will see it reliably and be able to make anything of it, using binoculars, from Earth. ]
[Question] [ So in many sci-fi franchises, there are these things called "grav-lifts" that supposedly cancel the pull of gravity of whatever they are placed on the bottom of. So is this possible? I understand that we don't have gravity manipulating devices, but in theory, would such a device be possible? If not, is there a way to mimic this effect? And I don't mean hovercraft such as we have today with an air cushion. I mean actually being able to hover or lift-off with a similar device. --- **Edit:** I seem to be getting a lot of elevator-related answers. I am not asking for levitation for the use of something like an elevator, I am asking it in the context of a hovering/flying **vehicle** [Answer] Easy answer: **~~No.~~ *Maybe.*** More complicated answer... If you ignore the word "grav" and look for any way to create levitation, it's hypothetically possible to create a magnetic field aligned to oppose the Earth's magnetic field to levitate an object. We see this the basic form of this effect already with superconductors. (Image courtesy the [Royal Society of Chemistry](https://edu.rsc.org/feature/100-years-of-superconductivity/3007335.article).) [![enter image description here](https://i.stack.imgur.com/IPAaJ.png)](https://i.stack.imgur.com/IPAaJ.png) However, today we can only do this using another magnet as the base reference for the levitation. In other words, while the science has the *potential* to lead to "anti-gravity" (or simply "levitation"), we can not in any way do it today. The problem, which is well explained [here](https://van.physics.illinois.edu/QA/listing.php?id=1027&t=magnets-floating-in-the-earths-field) is that the Earth's magnetic field is so large and so spread out that it is both weak and uniform at any point on or above the Earth's surface. This means that you need an enormously intense magnetic field, even using superconductors, to levitate. And with technology today, that's flat out impossible simply because we have no way to lift the weight of the energy-providing device along with the Clarkean magnetic emitters. And that's the core problem of why, knowing today's technology, the only valuable answer is "**~~no~~ *Maybe***." Thanks to various laws (like the really inconvenient laws of thermodynamics), we can't (perhaps, yet) see a way to produce that much power with a device that's so light that there's lifting capacity to *add a burden.* **But...** While the answer is that it's impossible today to do it, it isn't implausible such that it couldn't be used in a story. We have nuclear reactors that drive mighty aircraft carriers through the buoyant medium of salt water. The fact that we can build energy-creating systems that can propel objects much heavier than themselves implies that we just need to find the right combination of materials to do it for the sake of levitation. **Having said that...** The astute observer would quickly notice that I'm talking about levitation on a planet. Levitation on a space ship could be much, much simpler thanks to the need to bring the repulsive force with you. A plate on the floor that generates a strong magnetic field that the plate you stand on pushes against. It would be a neat trick to keep them aligned with any stability... but that's not beyond the possibilities of reason. But the ability to walk around with a single plate and levitate anywhere on a planet or in space? ~~No.~~ *Maybe.* --- **Edit:** @ChrisH linked a great article that changes my "no" to "maybe." * [Diamagnetic Levitation](https://www.ru.nl/hfml/research/levitation/diamagnetic-levitation/), an article from the High Field Magnet Laboratory of Radboud University. Which, among other things, demonstrates the levitation of a live frog. Frog... Human... it's just a matter of scale, right? [Answer] In Newton formulation of gravity $F=G$${m\_1 \cdot m\_2}\over r^2$. The general relativity formulation is a tad more complex, but it also states that a mass bends space time, and than bending causes what we see as gravity. In both formulations the only way to make gravity a repulsive force would be to have a negative mass. A negative mass would be such that if you pushed it with your finger it would move toward your finger, not away from it. Needless to say, at the moment we have nothing closer to that. So those devices are purely fictional. [Answer] # If They're Stationary, Probably As has been pointed out by other responders, negating gravity is hard or impossible. Maglev, as suggested by @JBH, is an approach. But, assuming that your "grav lift" is an architectural feature like an elevator, then there is another potential approach: # Acoustic Levitation So, recent developments in acoustic levitation use [acoustic vortices](https://www.zmescience.com/science/news-science/acoustic-tractor-beam-042342/) to suspend objects larger than the wavelength of the sound. It can be ultrasonic, and therefore not (directly) dangerous to human hearing, but at the moment the best that can be managed is a 2cm polystyrene ball. To levitate bigger, more massive things (humans, say) would require both better control over the vortices and a *lot* more acoustic power, but those are engineering challenges, rather than a matter of overcoming physical laws. Now, this wouldn't be practical for something that was less elevator-like, you're not going to get a [landspeeder](https://starwars.fandom.com/wiki/Landspeeder) from this, because the emitters have to surround the levitated object (at least in one plane), but if you absolutely, positively have to move a human (or similar masses) through the air from one place to another without putting them in a small mobile room, this is probably your best bet. (It is, however, *enormously* less energy-efficient then lowering a small room attached to a cable, and then hoisting it back up again.) --- I am including a link to [a video demonstration](https://youtu.be/nFJpEsKATXE) under the fold, because the link might eventually go bad, but it is supremely cool to watch. [Answer] Well, some time ago there seemed to be an accidental discovery of a "gravity shielding" effect in an experiment by Eugene Podkletnov at the university of Tampere in Finland. Created a lot of buzz for a short period and then died, so it was probably nothing, but I have come across arguments why it might be possible according to the known laws of physics. I believe it involved a spinning magnetic field in a superconductor, reducing the effect of gravity on all objects above it by some small percentage. Some random links that might help you on your way: <https://electrogravityphysics.com/gravity-shielding-finland/> <https://en.wikipedia.org/wiki/Eugene_Podkletnov> [Answer] No, not in the way these "grav lifts/antigrav lifts" are ***depicted in the literature***. **Surprisingly, this has nothing to do with (anti-)gravity.** A typical scenario would be: you return from lunch, enter the mgea-skyscraper at ground level, step into an "antigrav tube" and move up to your office on the 240th floor, where you and your lunch arrive, quite possibly, separately. The idea of this kind of life was perhaps inspired by a paternoster lift (<https://en.wikipedia.org/wiki/Paternoster_lift>), and movement in the lift tube is usually described just like that of paternoster lift, just without cabins. Now, with constant and human-manageable velocity (the passenger enters and exits the lift on his/her own, by means of a handle), this trip will take some time (let's say 15 minutes for single 240 floor trip). Basically, when you arrive at ground level, you can immediate embark on the return trip to your office because the travel time leaves no time for lunch. Which saves you from the embarrassing situation of you and your lunch arriving separately. Obviously, one "solution" would be to have constant acceleration (and deceleration) in the grav lift. So, on the trip from your 240th floor office to ground level, you would accelerate for the first half the trip and decelerate for the second half. Mathematically, with about 1 g-force of acceleration, you could expect to arrive in maybe 20 seconds. Practically, you will crash into Guido from the 120th floor after 10 seconds, at a speed of 350km/h. Lunch separation issues are now the least of your worries. Again, this is about how the lifts are ***depicted in the science fiction literature***. You might add accelerator tubes which bring the passenger up to some fixed travel speed before entering the main tube, and some clever exit system which pulls the passenger out of the main tube upon arrival at the pre-selected destination and slows them down in a separate decelerator tube. But that's far from being as "elegantly simple" as the grav lifts depicted in the literature. Another solution would be to "bundle" passenger with similar trips (this is actually done in real life right now, to increase the bandwidth of conventional lifts). You might even provide cabins for these "passenger bundles" (groups). Oh, wait. That's too much like a boring ordinary lift. Note that in very tall building, even the boring ordinary lift already accelerate (and decelerate) at 0.5 g-force - and this is already a bit of a lunch containment issue for some people. [Answer] ## Bonus Answer: Directional Gravity One issue with gravity is that it's omnidirectional. So if you can generate artificial gravity to lift an object away from the surface of the Earth (meaning 1 g-force of gravity), it would also affect everything else in the vicinity. And that's vicinity on a planetary scale. Basically, it would appear that you just created an Earth-size gravity source, in additional to the already present Earth itself. That sucks. Literally. The obvious solution is directional gravity (often called a "tractor beam" in the science fiction literature). To provide useful directivity to radiation (radiation like electric fields, or sound emitted/radiated from a speaker), the wavelength of the radiation must be significantly smaller than the dimension of the emitter. Obviously, with higher frequency we have smaller wavelengths, so higher frequencies will work better (like in audio, where higher bass is "hard to direct" and the treble is "hard to get omnidirectional"). We know that gravity waves exist. if we could generate gravity waves with device whose dimension is significantly that the wavelength of our (high-frequency) gravity waves, we could end up with directional gravity waves. That won't be perfect (just look up "antenna directivity" in Google), but it's clearly an improvement over good old omnidirectional gravity. Now, gravity waves don't help us very much, I guess. If they act like radio or sound waves, they do not move stuff around but cause stuff to vibrate around some position. All credit goes to **jdunlop** for mentioning Acoustic Levitation. I currently cannot rule out that **gravitational vortices** can be generated, just like the acoustic vortices mentioned by jdunlop - and that these could be used as some kind of "tractor beam". [Answer] There's a simple way to solve this: Superconductors. A superconductor is a material that's been chilled to the point where there's little, if any, electrical resistance, and running an electric current through a superconductor produces a powerful magnet. That magnet can be used to provide enough force to negate the weight of an object. ]
[Question] [ I assume it all comes down to how long would it take for the oxygen in an astronaut's helmet to evacuate. I figured it would happen in less than a second, and no sound would be picked up by the astronaut's comm. [Answer] ## About 15 seconds and they'll hear wind. I tried calculating this exactly and ended up with a lot of "depends". Human bodies swell pretty quickly when exposed to vacuum and this could partially seal the neck, slowing the wind to a long hiss. Theres a reserve oxygen supply in the backpack. They mostly filter co2 for the 8 hours of use but they can replenish consumed or leaked oxygen. That will be depleted fairly quickly. I cant find specs on maximum flow rate of this system but it will not be instant. 15 seconds is an educated guess from the diagrams of the system I can find. The wont hear screams as mouth and lungs will be in vacuum allmost immediately, they will hear wind, hissing, and panicked movements conducted through the suit. They'll also hear alarms from monitor systems and up links. Also the astronaut isn't instantly dead. You have 6 seconds of useful consciousness when this happens. With a bit of luck that is enough time to jump back into an airlock and smash the emergency represurise button. [Answer] I believe mission control will hear a very loud sound as the air screams out whatever opening it's leaving from at tremendous velocity. As the opening gets big enough this would go away, but almost all openings start small. [Answer] ## yes well sorta, lemme explain. a microphone works by measuring the compressions(and decompressions) of air, here find the microphone on your pc and record you blowing into it. It will make a wind like sound. so your unfortunate astronaut takes off his helmet and whoooosh a whole bunch of air comes out and by the microphone. if it was simply whats left in the helmet it would seem like a pop and then silence. of course its not just that air its all the air in the extra tanks. which means it will be some wind like sound that would get quieter and fade away pretty soon. also probably every alarm is going off. [Answer] The answer is an unequivocal yes, and the astronaut will even be able to talk to command control. The voice pick-ups and speakers are not regular mics, they are placed on the bones of the head and on the vocal chords. The headphones do not need air to operate, they go directly to bone conduction and into the inner ear. [Throat microphones](https://en.wikipedia.org/wiki/Throat_microphone) can pick up the vibration of the vocal chords. Head mics can pick up the vocal vibrations through the bones. Both of these are used in fighter jet communication systems, military field units, biohazzard suits, scuba gear, and in astronaut helmets. With Covid, they are even being used in operating theatres and emerency rooms. The astronaut could continue hearing ground control as long as life and power held out, and could speak as long as there was any air left in the throat, and probably a while after. How much air is actually in the helmet is not relevant. The ear drums do not even have to be intact. ]
[Question] [ So, as per my [Oxygen levels and explosions](https://worldbuilding.stackexchange.com/questions/188795/oxygen-levels-and-explosions) question, there is a planet with substantially lower oxygen (16%) and a planet with higher than average oxygen (25%) that are fairly earthlike in temperature, locked in a binary orbit around a sun-like star, far enough away that it is possible to travel from planet to planet with 1960 era tech. That was in the past, and it is now near future/2150 tech, and a rebellion of succession from low-planet. However, their tech level is scattered and thus is their weapons, causing lower oxygen to be relevant. In my original question, I stated that the plants were able to re-absorb oxygen and use it somehow to make energy. Alex-P pointed out that it is not likely for that to be possible. In short, I need a low-oxygen planet with high plant life and low animals. What is a feasible or semi-feasible reason why the planet has such an oxygen level? [Answer] ### Oxygen production and forest levels need not corelate! *Net* oxygen production by forests on Earth is [basically zero](https://www.pbs.org/newshour/science/no-the-amazon-fires-wont-deplete-the-earths-oxygen-supply-heres-why). Forests have microbes (and animals) which consume almost all the oxygen the forest creates. (In case it needs to be said ***This is not a reason to cut the rainforests down***) So answers to your question: * The ocean is responsible for most of the oxygen we're breathing now. So your lower oxygen planet has **lower algae concentrations in its ocean** - for example. * The lithosphere (rocks) are also responsible for oxygen levels. Some ferrous carbonate rocks (**siderite mineral**), Sodium/Calcium/Potasium/Magnesium ascorbate, or sodium hydrogen carbonate rocks (**nahcolite mineral**) exposed to the atmosphere. [![enter image description here](https://i.stack.imgur.com/DNP2E.png)](https://i.stack.imgur.com/DNP2E.png) [Answer] # Larger Oxygen Sinks, like dissolved iron in oceans In earth's history, the amount of oxygen in the atmosphere has not been constant, in fact there was a mass extinction event that corresponded to the drastic increase in oxygen (which was toxic to many of the existing life forms at the time). During this period there were a few sources of oxygen, one of which was photosynthesis, and there were also consumers or sinks of oxygen. Eventually the sources and the sinks balanced out. One of the most significant sinks was dissolved iron in the ocean, when the oxygen dissolved in the water it would react to oxidize the iron, which would then become insoluble, and sink to the ocean floor. If these deposits were a lot larger, the atmosphere's oxygen concentration would be lower. There are more oxygen sinks like volcanic gasses and methane, any one of these could also work by making them much larger compared to earth. Just by having larger sinks and decreasing oxygen concentration (and perhaps increasing CO2) would have the effect of increased plant life and decreased animal life, so that part is easily solved by the other. [Answer] Plantlife may be the source of your planet's oxygen, but their production is only *very* loosely coupled to the total oxygen levels in the air. For example, if *all* plantlife on Earth were to die, immediately, including all ocean plankton etc. Zero remaining oxygen producers. . . We would all die of old age before we ran out of oxygen to breathe. Assuming an infinite food supply, our great-great-great-great-great-great-great grandchildren (200 years) would notice the oxygen being about 5% lower than it is today.(this assumes we also keep all animal, insect and microbial oxygen consumers going, somehow.. if Only humans at present population?... about 250 thousand years)) The balance level is dictated (over **very** long timespans) by the rate at which oxygen is removed from the system, vs rate oxygen is added. Look to thinks like oxides of calcium and magnesium settling to the seabed, forming limestone deposits. We are talking long periods in geological terms! Millions to hundreds of millions of years. ]
[Question] [ How does a Neandertal compare with an anatomically modern human? This diagram below is a simplification of the real answer: [![enter image description here](https://i.stack.imgur.com/zgEci.png)](https://i.stack.imgur.com/zgEci.png) The average Neandertal male stood 64 inches tall, weighed 143 pounds and had a brain volume of 1600 milliliters. The average female stood 62 inches tall, weighed 110 pounds and had a brain volume of 1300 milliliters. Both sexes had to be larger and stockier proportionally because the climate of Late Pleistocene Europe was very similar to that of both Canada and Alaska. We have found no concrete evidence of Neandertals sporting both facial and androgenic (body) hair, but the possibility is a no-braining high. But if the Neandertals were smaller and heavier--enough to be analogous to the dwarf of modern fantasy--would they still need facial and body hairs? In this alternate Earth, both Neandertal sexes had the same brain volume (averaging up to 1600 milliliters), but the average male stood 48 inches tall and weighed 200 pounds, whereas the average female stood 43 inches tall and weighed 168 pounds. In short, smaller in height but higher in weight than our Neandertals. With 200 pounds of bone, muscle and fat compressed into a smaller body, this one question stands--**would the smaller, "dwarved-down" Neandertal still need facial and body hairs, or would the extra mass be enough to keep them warm in the frigid climate of Ice Age Europe?** [Answer] Hair is not only for protection against cold, especially for such "naked" creatures like humans. It is also 1. Signal. Sexual mostly. Telling females from males is a must for creatures with less than 100 offspring per female. But it is also used to tell the young from adults and adults from elders. This allows to prevent many one-sided conflicts, and keeps aggression at some control (until some stupid apes invented weapons "to make everybody equal"). And so on. 2. It is a physical protection against stones, thorns, claws, fangs, and insects (it's also home for other insects - but this is different story) 3. They help to spread scent. Again for different signaling process. There is nothing better than the smell of your home borrow where dozen of human creatures leave with limited access to water! It all means that neanderthals needed hairs even more: * they are smaller, so at the same distance less features are visible - they need bigger headdress * They were unable to throw things (compared with us), but were very strong (compared to us). So all encounters they had with prey and predators were close ones. And they really needed additional skin protection * Human "fur-scheme" is due to the evolutionary process of [neoteny](https://en.wikipedia.org/wiki/Neoteny) (we look like newborns to gorillas). So if neanderthals are less evolutionarily developed they must be closer to other primates It all means that most probably they were and should be much more hairy than humans [Answer] Apes do not have hairs for cold climates, apes have hairs to avoid freaking skin burns....my brother cut his hair bald and now his skin is falling in flakes mixed with blood because he got burned by the sun. Modern humans are less hairy than other species of apes because we do not stand in the sun all day long. Most of the time, some people who enjoy skin cancer do get a sun tan on purpose at the beach. Humans have just as many hair follicles as gorillas or other chimps, but our hairs are thinnier, too thin to be visible. Also Neanderthals were not shorter, just like every generation of humans gets taller...not because of evolution but because of better nutrition. Neanderthals were just malnourished, just as ancient homo sapiens were too. But to answer your question, no facial hair is not needed. China lived in the cold for millenia yet Chinese people with a full beard or even partial beard are incredibly rare. [Answer] The temperature receptors are located in the skin, if I recall correctly, therefore larger fat reserves would protect internal organs from extreme cold (they would theoretically survive a bit longer), but it would still inflict pain and frostbites. Therefore I believe the hair is still necessary, regardless of body mass. ]
[Question] [ In paper, the reason why Joerg and various whacky bows and crossbows made a return and phased out guns in this setting is because of two factors: * **Cheap homing arrows**. Even anti-material rifles, like the .50 cal, aren't worth much when you don't have to be in the line of sight to hit its user. Sure, a Barret is a long-range weapon, but the cloaking and obfuscating tech is ought to take care of that. And by obfuscating, I mean a White-Walker-style personal fog, that you can apply to the enemy or yourself, at your convenience. * **The arrows are capable of delivering deadly payloads**. The most common one is an air-fuel explosive, which has enough power to cause severe internal bleeding and death via drowning in your own blood. There are other factors, of course, like the complexity of firearm production, an abundance of high-strength armor materials, and sectoids that can mind-control people, which is instant-TPK (total party kill) when it happens to the gunner of the squad. For now, let's focus on the homing arrows. I need them to be easy to make with an increased range, homing, self-steering, and the ability to carry a payload with minimal increase in drag. **How could such an arrow work?** [Answer] In WWI, aircraft sometimes dropped flechettes on the enemy. During the Viet Nam war, this was revived in the form of the "Lazy Dog", .50 caliber bullet sized projectiles that simply fell from the sky and killed though kinetic energy. [![enter image description here](https://i.stack.imgur.com/cLXtX.jpg)](https://i.stack.imgur.com/cLXtX.jpg) *WWI era Flechette* [![enter image description here](https://i.stack.imgur.com/CFBzr.jpg)](https://i.stack.imgur.com/CFBzr.jpg) *Lazy Dog projectiles* The issue with arrows is unless there is a very powerful bow, like a steel crossbow with a 1200 lb draw (and using a winch mechanism to span), you might not have the ability to loft an arrow high enough to carry a seeker and warhead, much less be high enough to have a wide scanning area and sufficient kinetic energy when it drops from the sky. Adding extras like a rocket motor simply compound the problem (the rocket would make the arrow quite heavy, and need to ignite on launch in order to provide the "loft" needed, endangering the archer). The actual seeker head on the tip and actuators moving the fetching isn't really a big deal, this is essentially how ATGM's, guided missiles and even "smart" artillery shells work. Modern technology has brought this down to the size of 81mm mortar rounds, "Mini Spike" APGMs (Anti Personnel Guided Missiles) and even (without the actuators or fins) 20 and 25mm "smart" grenades designed to be fired by rifle sized grenade launchers such as the XM-25. Where your idea fails is the arrow isn't going to be moving fast enough to really get a great deal of control authority from the small fins, or even much range, especially compared to modern firearms, rockets, missiles and artillery weapons. The mechanical energy stored in the arms of the bow isn't sufficient for that sort of task. A large explosive or Fuel Air warhead makes the arrow even heavier and slower, and thus less effective. Adding a rocket motor essentially negates the need for a bow in the first place. The only other "arrow" which can overcome these issues is the type which is fired from 120mm tank cannons - an APDS-FS round. This gives the combination of range, striking power, speed for control authority of the fins and actual room for sensors and actuators (although at this time no one has actually produced a guided APDS-FS round). For an explosive warhead you would be looking at HEAT-MP rounds. The closest things to what you are talking about are "Through Tube Missiles" (guided missiles fired through a tank cannon, like LAHAT, with a range of 13km), or the K-STAM (Korean Smart Top Attack Munition) which has an 8 km range and seeks enemy armour in the terminal phase, using its sensors and fins to position itself over the top and fire it's HEAT warhead down through the roof of the target). No bow that a human could easily carry can launch a guided arrow with the sort of performance that is comparable to modern weapons in terms of range, maneuverability or payload. You are probably looking at a ballista to launch a guided arrow. [![enter image description here](https://i.stack.imgur.com/sbnPz.jpg)](https://i.stack.imgur.com/sbnPz.jpg) *This has the mechanical energy necessary for a long range, guided arrow with an explosive warhead* [Answer] Giant trained kamikaze dragonflies. The modern equivalent is modern LMAMS, portable lethal drones like the SwitchBlade and Hero-30, which have longer range and higher precision than firearms and may make them obsolete. Biological systems like birds have broadly similar flight characteristics; a giant dragonfly would be much cooler and removes the need for technology development. They could be trained to dive into soft targets and then used against live humans. [Answer] Little mini drones with kamikaze built in. Thrown like grenades in the general direction of the enemy, then extruding it's propellers and continuing in the same direction, accelerating and attacking the first enemy of a specified type. Man, Tank, Horse, Goblin, Witch Lord or Time Lord, Sectoid, whatever you tell it before throwing it. It can then fly into the face of the sectoid or whatever else part isnt armoured. The armpit. The ear. The neck. There it releases the payload, be it a little explosive, poison, sectoid mind control stuff, a flashlight to blind those guys or just a message. Or it just accelerates until it hits with 500km per hour. If it can achieve 2000km per hour even for a very short time and has a nice pique design on the nose like an arrow, it becomes armor breaking. You could think about varying degrees of sensory, the cheap one which is blindable by the whitewashing, the expensive one which even looks through the whitewashing but takes up the place of the payload. And the deluxe one where a swarm of those things sits in every corner of the city and stitches together a real time view that is sent to the central for the attack of the army. Wouldn't like to live in your book, though. [Answer] Make the arrow out of four different types of metal. Each of the metals must have different specific heat capacity (<https://en.m.wikipedia.org/wiki/Specific_heat_capacity>) As the arrow flies, it will flex. This because of heat transfer. Suppose your target is slightly to the left of where the arrow is headed. Heat from the target will transfer to the arrow. Each of the four strips metal will expand due to the heat at different rates, causing the arrow to flex... and thus be able to steer itself. \*\*Note: this will only help account for minor adjustments. The arrow won't be able to drastically change course. To save on production costs, you could make it out of just two strips of metal. But it would only be able to steer in two dimensions, which might not work if it's rotating. The metals must have very low specific heat capacities because heat needs to transfer in the very short time of the arrow's flight. Something like zinc. Or, if you're ok with mythical substances, make something up that has a super small heat capacity. \*\*Note: If you're ok with mythical (or yet to be discovered) elements, two strips of metal will definitely be sufficient. Pick something with a specific heat that's almost zero. The element for the other strip can be anything. As the arrow rotates, the strip made from the mythical element will flex instantaneously. When the strip is on the opposite side of the target, it will expand, causing the arrow to point at its target. But when it rotates and now the strip is on the same side as the target, it'll contract. You'll need the other material to be made from a material that contracts easily but doesn't expand well so that the arrow is continually bending towards its target. Research "expanded metals." Because they're already expanded, they contract easily.... up to a point. Or, if you want to be gruesome, bone has a very low specific heat. Not as good as zinc, I'm afraid, but fusing together bones from two different types of animals just sounds cool. ]
[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/171316/edit). Closed 3 years ago. [Improve this question](/posts/171316/edit) How long would it take to train a medieval pesants to become a decent: * spear & shield soldier * foot archer * mounted archer * knight equivalent for commoner (man at arms?) For each unit type separately. The assumption is that you have enough money, equipment & instructors. There are plenty of ambitious recruits who want to join the army. Peasants have no experience in fighting beside drunken brawls, nor riding beside donkeys. This happens around 1000 AD. [Answer] 1. **Spear and shield infantry** - around **a month** as absolute minimum. Hypothetically, a man can fight with spear and shield pretty fast, but you also need to train them to keep formations, etc. If they can't do that, they're going to be near useless on battlefield. 2. Archers - forget about it. Crossbow soldier is an option, but Archers require a lot of training. Your best hope is if you have some people who use hunting bow, but you won't have many of those, as nobles usually keep the hunting rights, so only people who're assigned by them as **huntsmen** will be possible for you. You might **convert** them **into acceptable archers in a month**, but **for normal people, it might take over a year.** But for training a **crossbow soldier**, on the other hand, **month or two is enough.** 3. **Mounted Archers** - no, just **NO**. Archery alone is a difficult skill to gain. Horseriding alone is difficult skill. Now, for a person with no previous skill in either to learn both, and also learn combined skill of shooting from a horseback - that takes time. You're looking at **2+ years minimum**, assuming you have people who can teach mounted archery. 4. Pseudo-knights - Now this depends on what you imagine by knight. **Armoured** heavy infantry **footsoldier**? **A half year is complete minimum**, and you might want a year(for example [Roman legionary](https://en.wikipedia.org/wiki/Legionary#Training_and_discipline)). **Armoured cavalry with lances?** Now again, like mounted archery, you look at **minimum of 2 years.** [Answer] **Spear and Shield: A Few Weeks of Drilling** The spear is the easiest melee weapon to use and was the core armament of all medieval armies. If you want effective troops than you’d actually need them to understand drill. Knowing how to march in step, facing movements, and obeying commands are all critical, and can be learned quite well within 7 weeks. I know this from personal experience, because modern militaries still teach the core essentials of marching. **Archers: Years** Although the basics of archery can be picked up in a day, it takes a lifetime to master. It requires significant strength and skill, so much so that we can identify the skeletons of English Longbowmen by their thicker arm bones. Archery was such a valuable skill that requires so much time that there was a law in England for several centuries that mandated the practice of archery on Sunday, a day when all other work was prohibited. Archery can be very effective for a peasant army if it was already an integrated part of their culture, like it was in England or Korea. **Knight: Lifetime** Knights started their military training when they were about 12 years old. Effective horsemanship takes years of continual practice to become good at, because you have to know how to control and trust a powerful animal and bring that animal into a brutal fight against other men riding big animals. The knight needs to be skilled enough to ride fast and hard while wearing armor, and once he makes contact he has to be able to fight from atop his horse. Being a knight also entails using weapons that require much more skill than the common spear or cudgel. Swordsmanship also takes years of effort to become decent at, and fighting in armor is also a skill in of itself, even in the mail hauberks of 1000 AD. (Note: knights in 1000 AD are going to be in chain mail, not plate so they will be using swords kite shields more than maces, hammers or poleaxes.) **Horse Archery: Generations** It takes years to master archery and years to master horsemanship, so you can see where this is going. Horse archery requires a specific set of cavalry skills and advanced archery skills that were available to only available to two kinds of Warrior. The first were elites like samurai who spent their life training like knights, and the second were steppe nomads. Nomads were such skilled horse archers because they spent literally their entire life preparing for it. They rode horses from an extremely young age and practiced with bows from an extremely young age, and then they practiced horse archery to get all of their wild game. European peasants as settled farmers just don’t have the ability to do this nor do they even have the right environment. Unless if you’re being generous with what counts as “peasant” because you could have poor nomadic herdsmen in Russia or Ukraine who were vassals to some boyar, but I kind of doubt that’s what you had pictured [Answer] Well this a rather interesting question since the general rule of 1000AD was there was no formal military training as we would recognize it and for most "decent" meant "living long enough to let the professionals do their work with some degree of safety"...in short, learning formations. Luckily, this can be done rather quickly for this most part spear and shield...easy enough - the the pointy end forward, keep your shield up, stay in formation. This can honestly be drilled in over a matter of weeks, definitely within a month. foot archery is a bit more complicated...not the archery part, after all archers just need to fire in volleys...nuf said. The issue is getting the troops strong enough to draw bows that are actually effective against the enemy...which depends on the armor of the day and thus creates a highly variable timescale. But lets just say there's a reason in 1360's Edward III made archery practice mandatory on every Sunday and holiday for all able bodied men (ensures the muscles are built up) so starting from scratch means years before pay off actually happens. Mounted archery is even worse - sure the bows are lighter (read that as easier to use and less effective in battle), but it still takes a while to train the archer to shoot...and then there's the horse, not only is a matter of getting the horse of the right temperament but it also needs to be trained (something taking anywhere from a week to a couple months). As for our knight equivalent...knight training itself could easily take a decade, but that also included nonmilitary education. Even so there's a plethora of tasks to master: horsemanship, lances, swords, tactics...the list goes on and some anecdotes joking anywhere between 2-5 years of training being involved simply because of how much investiture goes into the force just on equipment ]
[Question] [ Medieval houses generally made out of timber were often being raided by several dragons that can breathe chemical fire at a distance. They seldom touch the houses with their razor sharp talons nor topple it with powerful tail, they simply flew around in circles and spew fires(napalm) at the houses and trees. What kind of houses can the medieval folks built to stand up against these airborne flamethrowers? [Answer] **Dirt** When all else fails, dirt is reasonably cheap and fire resistant. Build the house out of a frame, and then just slather a thick layer of mud all over the top and sides of the house which should provide a reasonable protection against fire. Also serves as a decent insulator too. [Answer] [![Middle Age house Construction](https://i.stack.imgur.com/zjsuA.jpg)](https://i.stack.imgur.com/zjsuA.jpg) The frame of the house can be wood, but roofs, with proper reinforcement, can be slate. And the walls can be daub and wattle. The wooden wattles wouldn’t provide protection, but the daub would be fire proof since it is little more than gypsum and plaster, treated with water proofing. Also, if needed, green hides of slaughtered animal could be nailed to walls and doors to provide additional protection. [Answer] Give the dragons a different target. Use fake houses - more just shaped piles of kindling that turn into a bonfire when set alight. Even use strawmen as well, to make it look habited. The real houses are all low profile, hidden underground wherever possible, but the decoy houses are used to draw the dragons fire elsewhere, to a safer part of the city. The dragons come every week, burn down the decoys, but it's easy to just rebuilt afterwards. Otherwise, what do the dragons actually want? If they never land, then presumably they're not actually raiding. If they just want to snatch meat, then pay them off - leave out fresh butchered meat for the dragons, and presumably leave it in the decoy houses for the dragons to take. Dragons get fed and leave, nobody gets hurt. If you want to be spiteful, poison that meat. [Answer] It's best to build your houses from either dirt (as mentioned by other answers) clay, brick and mortar, slate, or stone blocks. Any stone or aggregate based building material would stand up to fire much better than organic materials like wood and thatch. That being said, a bunch of napalm-like fire would still do significant damage, so damage control would be something you'd look into. # Caves/tunnels This would be my choice if dragon attacks are on the order of the day. In medieval times (and even now), there's hardly a better defence imaginable than a massive slab of mountain or dirt overhead. The only thing that can get damaged is the entrance, and if you have multiple this isn't too much of an issue. # Aqueducts A bit of an out-there solution, but not infeasible. The romans managed to build massive aqueducts to irrigate their fields and cities. A large aqueduct network throughout the city could help massively with firefighting. Built of stone bricks and doused in water, the aqueducts themselves would stand up to the fire attacks quite well. Any houses that would be hit and burning, one could remove the shutters on that side of the aqueduct and douse the house in water, instantly putting out the fires. This could even be done pre-emptively when a dragon is spotted, so that the wet houses would not take as much damage. ]
[Question] [ Set in the medieval period, the benevolent gods periodically post requests for brave mortals to go on an adventure of a lifetime. There are usually no rewards upon successful completion of the quest. There are no save points along the way where the adventurer may head back to town and restock or respawn. Fatalities for partaking such a quest are higher than those for contracting the Black Death. The gods do not have obligation to intervene in the people's business, and they can restart genesis if everybody is gone. People are just a pawn to them, but still there are men and women forming a line to sign up for the perilous vacation. What can be the incentive for them? Many of those adventurers do not worship the gods nor do they fear the gods. [Answer] ## Initiation rite to enter in a powerful group Initiation rite and rite of passsage exists in many cultures and organization. Sometimes, it's just symbolic, such as the baptem for christians, but it can be way more brutal. There are several examples, such as spartans, who were taken away from their family for militar training, and need to kill zelot without being discovered to validate their training, or gagns that make you commit a crime before you enter in the organization. Your sect may have religious roots, without making all members zealous. However, in order to be accepted as a member, one need to achieve a quest given by the gods. If this society is prestigious/powerful/rich/whatever, it can be a pretty powerful incentives, and promise a good career for all the ninth-born sons who have nothing to lose. [Answer] There’s a lot of things people do without promise of a reward. Dangerous, arduous things. Like fighting massive bushfires. Thousands of firefighters converged on Australia this year to fight a particularly awful bushfire season, most of them volunteers. None of them will get much more than a medal and recognition for a job well done (maybe a small stipend to compensate for the protracted deployment), but they went out anyway. Why do they do it? Well, for some it’s their job. For others, it’s because it’s their homes in the line of fire - either immediately or if they lose control. And for some it’s because it’s just the right thing to do - like the Americans who flew in from California. The same motives can drive people to fulfil your gods’ requests. A knight may go slay a rampaging dragon because he’s responsible for defending his realm, nevermind that it’s really the latest spat between a couple of gods he doesn’t know or care about. A smith’s daughter may journey deep into foreign lands to smash the staff of the sea god because the tsunami it would cause would destroy her home town. A band of vagabonds might undertake to battle the evil Cult of Novel and Hurtful Slurs simply because it ought to be done. The perilous mission to the firey caldera of Mount Doom to throw in a couple of tim tams and a cuppa may have trouble finding volunteers [Answer] > > What can be the incentive for them? Many of those adventurers do not worship the gods nor do they fear the gods. > > > Imagine that many *ordinary people* believe in the Gods, even if experienced adventurers are more cynical. So it is a good idea for the upper classes to at least pretend that they believe as well. Usually not to the point of going on suicidal quests themselves, but certainly enough to cheer those who go on. *"Slay the dragon perform the quest and win the hand of the princess and half the kingdom. Or the eternal gratitude of the crown, at the very least."* Add an upper class/noble culture where the oldest son inherits the title and the entire family fortune. The second son gets a small allowance, daughters get dowries. Yet infant mortality is so high that there must be *a heir and a spare.* So what do you do with those landless *second sons?* Some go into church service. Some become courtiers at the court of a brother or cousin. But those who want to become something in their own right, they have to take risks. Start a civil war. Support the pretender in a foreign civil war. Go on a quest. [Answer] > > The gods do not have obligation to intervene in the people business and they can restart genesis if everybody is gone, people are just a pawn to them but still there are men and women forming a line to sign up for the perilous vacation... > > > Take a page from The Order of the Stick. The Gods are trying to contain a universe-destroying entity, but they can't fight it themselves. Only mortals can. So the Gods send them mortals against the beast because the alternative for the mortals is to cease existing (not death - I mean literal nullification). Whenever mortals botch things up the Gods create another universe to try and fight the entity again. ]
[Question] [ In the future gas giants, ice giants, mini neptunes and gas dwarfs have been colonised. The colonisers use either hot hydrogen or vacuum in rigid ballons to keep their cloud cities up in the endless sky. The colonisers would want to get around, so they need some kind of vehicle. While vehicles will obviously be personalised to fit more specific needs, I belive that there will be a number of characteristics which most of them will have in common. There are the ones I came up with. A vehicle doesn't need to have all of these characteristics, depending on its purpose. * in-atmosphere engines: turbine, ramjet, scramjet The normal turbine engines will be used to manover and to get up to speed and the ramjet and scramjet will be used for travel. Helicopter style propellers might be used for manovering as well. * power: chemical, monopropellant, nuclear The chemical option would mean carrying oxygen on bord as fuel, as it can be burned with atmospheric hydrogen. The monopropellant option means metallic hydrogen, which can be produced in the cloud cities. Nuclear would mean He3+De fusion. This is a common technology in the setting, as it was perfected for spacecrafts, and the atmospere of a gas world is full of fuel. Waste heat management won't be an issue as it will be on a spacecraft. In my opinion nuclear is the best option by far. * deployable units for lighter-than-air flight The ability to decrease the vehicles density so it can rest somewhere in the atmosphere is interesting for many purposes. Some vehicles might be actual airships. The ballons would either be filled with hot hydrogen or be rigid vacuum carriers. * space capability If metallic hydrogen is used, the vehicle actually is a rocketship already. Oxygen and Nuclear based vehicles would need to take on hydrogen as ejection mass. Space capability is interesting as it would allow faster travel around the planet and rendezvous with real spacecrafts. **Are there other general characteristics a gas planet vehicle should have?** [Answer] Here's a great place to start: [Interplanetary Cessna - XKCD What If?](https://what-if.xkcd.com/30/) As a human on Earth, you have a great advantage in determining what you need, in that the Sol system has 4 gas giants of its own, each fairly well-studied and visited by numerous probes. Randall Munroe's What If question focused on using an ordinary Earth airplane, the Cessna 172 (one of the most common in North America) which, for most of the gas giants, turns out to be an example of what not to do. [![enter image description here](https://i.stack.imgur.com/ILiUE.png)](https://i.stack.imgur.com/ILiUE.png) Let's model your own gas giant after Jupiter; it's not quite as friendly as Saturn to air travel, but it's the first gas giant a casual reader will think of, and most planets we know of are "super-Jovian" gas giants even bigger than Jupiter. The problems you'll face get bigger as the planet does, because the planet's gravity limits the thickness of an actual gaseous atmosphere. Your habitable range of Earth-like atmospheric pressures will end up about the same height above the transition to a liquid layer, meanwhile the gravity of that ever-bigger ball of liquid hydrogen under you will make it that much harder to stay afloat as the size of the planet increases. If you can solve Jupiter's problems, it will be that much easier to solve problems of a smaller giant like Saturn, and you'll have that much more of a leg up on the problems of a superjovian. Here's a short list of the things your Jovian airplane will need: * **Oxidizer where fuel normally goes.** Most gas giants are primarily hydrogen; there's relatively little of anything else *but* hydrogen in any one place to make a planet of this size (while we have found "mega-Earths", primarily solid planets many times Earth's mass, superjovians are much more common among cataloged exoplanets to date). That means that your airplane is flying in its own fuel, unlike an Earth aircraft which flies in its own oxidizer. Your engines, if "air-breathing", will actually aspirate the hydrogen atmosphere, combine it with oxygen from its internal storage tanks, and ignite that mixture to produce thrust from heated gas. It's kind of a backwards way to think about it, but as long as you get the mixtures right it works exactly the same way (other than the fact that mostly for safety reasons but also for some practical ones, modern airliners don't run on hydrogen). * **Big wings and lotsa thrust.** At atmospheric pressures comparable to Earth's atmosphere, the gravity of Jupiter is about two and a half times as much as on Earth. Go higher to reduce relative gravity, and you'll have less gas flowing over your wings to generate lift and through your engines to produce thrust (and you won't get anywhere near Earth gravity while still in anything you'd call Jupiter's atmosphere). So, you need a plane with about 2.5x the lift-to-mass and thrust to mass ratio of a plane designed for Earth, because that same plane, of the same mass, will weigh 2.5x as much in Jupiter's atmosphere, and so lift-to-weight and thrust-to-weight will be reduced by that same factor. We have to deal with this kind of math fairly regularly in designing Earth aircraft. The interior volume of a passenger aircraft is a rough analog of the plane's max takeoff weight, due to a combination of regulations, physics, and plain old common sense about things like minimum airspace per passenger that keeps them coming back for another flight in your sardine cans. The heavier the aircraft, the larger its wings must be, however wings don't scale the same way fuselages do; if the wing's cross-section gets too thick, you end up increasing leading-edge drag too much, so the most efficient airfoils for large aircraft remain relatively thin as wingspan and chord length increase. This means that superjumbos like the B747 and A380 have much larger wing areas as a ratio of their fuselage "footprint" compared to smaller "single-aisle" jets like the B737 and A320. Your Jovian aircraft, for the same volume, will weigh 2.5x as much as on Earth. We can compensate for that in Earth's atmosphere by simply increasing mass by 2.5x for the same volume of aircraft. As it happens, the Boeing 737-800 and the Boeing 767-300ER have almost exactly the necessary relation in max take-off weight. So, in theory, if you take the 767's wings and engines and put them on a 737, you have about the necessary lift it would take to fly that 737 on Jupiter. That would increase the wingspan by about two-thirds (from 93' to 156'), and would about triple wing area (979.9 ft^2 to 3050 ft^2). You'd also go beyond any possibility of the engines being underslung on the wings (the up-engine to the -300 series already necessitating the noncircular "hamster-pouch" engine nacelles) and so you would have to find some other agreeable place on the 737 to put the 767's 8-foot-diameter CF6 engines. * **Totally sealed interior, at least for oxygen-breathing inhabitants.** Jupiter's atmosphere again being mostly hydrogen, you really don't want any of that within livable spaces of the aircraft. Hydrogen has one of the wider flammability ranges of any flammable gas; in concentrations as low as 5% and as high as 95% in otherwise Earth-proportioned air mixture, you will get ignition, and in anything but the absolute extremes of that range it will explode quite spectacularly, with the stoichiometric ratio of hydrogen in air being about 9.5%. So, while your plane doesn't actually have to maintain that much of a pressure differential to fly in Jupiter's atmosphere (though you would get a similar drag-reducing benefit flying higher than Earth sea level pressures, and you'd probably want some sort of crush pressure rating in case a plane descended deeper for any reason), the passenger cabin must be *totally* airtight. The problem is that airliners are not and have never been airtight; they circulate outside air into the cabin from the initial compression stages of their engine, cooled with heat exchangers, to maintain sea level pressures within the cabin. Even at a quarter-billion dollars or more apiece, it's just too expensive for the manufacturer to deliver an airplane that is *totally* airtight, and too expensive for the airline to keep it that way, not to mention that changing the air within the cabin is the easiest way to mitigate objectionable smells (like the passenger three rows up who *really* should have showered before getting on a plane). Positive cabin pressure, fairly easy for most phases of flight, would ensure that any hydrogen-oxygen mixture due to leakage happens outside the plane, but that oxygen would need to be replaced, which is its own problem. * **Total IFR with Satellite navigation.** We casually view a city built over a gas giant to look like Bespin from Star Wars; a towering metropolis nestled conveniently in the upper cloud layers of the planet from which it's extracting useful material. [![enter image description here](https://i.stack.imgur.com/UeBpE.jpg)](https://i.stack.imgur.com/UeBpE.jpg) In reality, at Earth pressure, what you're going to get looks less like Bespin and more like Beijing, when the Olympics *aren't* in town: [![enter image description here](https://media.pri.org/s3fs-public/styles/story_main/public/photos/2014-February/beijing_filthy_air_1.jpg?itok=luOmDgwv)](https://media.pri.org/s3fs-public/styles/story_main/public/photos/2014-February/beijing_filthy_air_1.jpg?itok=luOmDgwv) In flight, there are two basic sets of rules for flying. Visual flight rules or VFR are for when you can see where you're going. Instrument flight rules or IFR are for when you can't. Jupiter's atmosphere at Earth-like pressures will definitely be the latter, requiring pilots to rely primarily on instruments to navigate. That in itself is not as big a problem as it sounds; airline pilots fly using IFR almost all the time for a combination of safety and practicality. The problems center around the very basic difference between Earth and Jupiter; nothing is anchored to the ground, because any "ground" to speak of is tens of thousands of miles deeper and thousands of degrees hotter than anyone or anything can survive. Jupiter does have a magnetosphere; quite a strong one in fact, about ten times the field strength and 18000 times the magnetic moment, so the biggest problem you'll have with a traditional compass is dealing with severe magnetic dip (the magnet will orient along the lines of the magnetic field, which are not perpendicular to gravity or parallel to the "surface" along which you're flying). A fluid-filled spherical compass would need to be a little larger than usual to keep the azimuth lines accurate and readable at higher latitudes of the sphere as the compass dips, or you could just ditch the magnet and use solid-state magnetometers, which are what modern airliners use (because the data can be easily fed into digital flight displays and computerized flight directors/autopilots). The bigger problem is that, very unlike any terrain feature on Earth which would only move relative to very far-away objects on other plates, and even then only at a rate of a couple inches a year, a city floating along in Jupiter's atmosphere will be carried along by zonal jets averaging about 60mph, and buffeted by true storms that exceed even the Enhanced Fujita scale for tornadoes, with wind speeds over 350mph. These zonal jets move in opposing directions, so more than one city at more than one latitude (which you'd have, otherwise why bother flying) would mean that flight plans between the two cities would look more like orbital trajectories than terrestrial travel plans. Your reckoned course from one city to the other would have you flying along a path that compensates not only for the distance the destination city will move along its own zonal stream during your time of flight, but the relative wind speeds of all the layers you'll travel through on your way there, which will blow you left and right as you move north or south around the planet. You do have to account for the prevailing wind direction and average speed on Earth, as you will be flying through a mass of air that is itself moving relative to Earth's surface, but the triangulation required for your average terrestrial flight plan would have nothing on the math to reckon your course around Jupiter. And, weather conditions can change. "Dead reckoning", a purely mathematical, instrument-based course-calculation, is called that for a very good reason; you are right, or you're dead. Even IFR on Earth requires the pilot to use visual cues to correct for any inaccuracy, and most private civilian navigation is done using waypoints based either on terrain features or navigational beacons at precisely-known locations (which broadcast signals that allow you to know your exact bearing from that beacon, and knowing the angle of azimuth from each beacon gives you a triangular fix of your location). Once again, nothing on Jupiter's surface is in a fixed location, so there is no such thing as a "terrain feature" or a "navigational beacon" from which to triangulate. The solution required would be similar to the system we've had since about 1997; the Global Positioning System. A constellation of satellites in a very precisely-calculated system of orbits, with very finely-synchronized chronometers aboard, such that every position on earth is within line of sight of at least 4 of these satellites. The position of any satellite at any given point in time after the system's initial epoch can be calculated based on their known, stable orbits, and each satellite is sending a time-coded bitstream that allows the receiver to calculate the "time of flight" of that signal, which when multiplied by the speed of light, gives you the distance to that satellite. Knowing the distance to one satellite, along with its current position over the earth, means you are somewhere along a near-circle on the idealized Earth's surface (a perfectly smooth oblate spheroid) that you'd get by drawing on a globe using a pencil of that length anchored at the position of the satellite. The measurement from two satellites gives you a second intersecting circle that ideally provides a maximum of two possible locations on the Earth's surface that you could be, and three different satellites will in most cases give you a unique position fix within the margin of error of the distance measurements. Four are typically used in GPS to guarantee an accurate fix, because the orbital dynamics of the constellation mean that two satellites can be relatively close in position which reduces accuracy. Navigation in Jupiter's atmosphere, within which nothing is in a totally fixed position, would require a "JPS" system that would give similar distance-based position fixes within Jupiter's atmosphere. Ideally, signals could be received from below what would be Earth's horizon, which would allow altitude calculations based on the calculation of your position in 3D space, reducing reliance on a pressure altimeter (vital but troublesome even on Earth, as surface barometric pressure can change by enough to matter in less than an hour). If you're going to get from one city to the other, and you're not *absolutely sure* of the wind speeds in the zonal jets between the two cities, this is the only way you'll get close enough. * **A steady supply of both oxygen and an inert gas.** When we're talking about breathing oxygen within a hydrogen atmosphere, things get much more difficult. The pressure differential isn't even that much of an advantage, because you still can't have any leaks; any slight pressure differential between inside and outside will leak one gas into the other, and as I said before, hydrogen gas in an oxygen environment has a ridiculously wide window of flammable concentration, which only gets wider when you enrich the atmosphere with a higher partial pressure of oxygen. That's the first problem; Apollo, the Space Shuttle and even early space stations like Skylabs and Mir got by on a low-pressure, oxygen-rich atmosphere. This reduces the required pressure handling of the spacecraft, and also reduces the amount of tanks of gas that have to be dealt with to maintain the proper atmosphere. The ISS, designed for longer-term stays (and with more frequent unmanned resupply launches) incorporates nitrogen into the mix, which reduces flammability in the environment, increasing safety, and also reduces the aging effects of high-oxygen environments on human tissues ("antioxidants" are essential vitamins for a real good reason; while we run on oxygen, it also causes cellular damage and aging, and these effects increase with concentration). Either nitrogen or argon (a totally inert gas) would be that much more necessary when the outside environment isn't a vacuum, but instead a ready supply of go-boom. Airlocks can't just pressurize with an atmospheric mix, they have to first purge the hydrogen completely before adding oxygen, otherwise you're creating a fuel-air bomb in your airlock as you oxygenate it. That means nitrogen is a "consumable"; you blast it into your airlocks as an intermediate step between introducing oxygen or hydrogen into that chamber, so those two gases are never in sufficient partial pressures to become a fire hazard. This will almost certainly require expelling quite a bit of nitrogen out into the outer atmosphere, just to be sure you have *all* the hydrogen out. Overall, a slightly positive air pressure within oxygenated habitats is preferable, because then any leaks at least leak oxygen out into the surrounding air where wind currents dissipate it into harmless concentrations relatively quickly. But this creates a problem; that oxygen leakage is gone forever. You can't reclaim it from the Jovian atmosphere. Neither, for that matter, can you reclaim the nitrogen. Once it's been released into Jupiter's atmosphere, it has to be replaced from some other source. Why is that, you ask? Well, because these gases are denser. At the same pressure, both oxygen and nitrogen weigh much more than hydrogen, which is why a balloon filled with it floats in Earth's air. In Jupiter's hydrogen atmosphere, the opposite happens; any oxygen that enters the Jovian atmosphere will sink into the depths of the planet, until it becomes hot enough that combustion to produce water vapor (or, for nitrogen, hydrogenation to produce ammonia) becomes favorable. That water is even denser, and will continue to sink into the increasingly dense, high-pressure supercritical liquid mostly-hydrogen oceans of the Jovian "surface", far deeper than any human man or machine could hope to venture. Even if we could get down into deeper layers, the best we can hope to pull back is ammonia (NH3) which is theorized to exist in some abundance in the intermediate layers of Jupiter's atmosphere. We can dehydrogenate ammonia pretty easily by burning it in oxygen (that process is *far* easier than making ammonia on Earth; the Haber process requires temperatures and pressures not unlike what you'll find a few miles below Earth pressures on Jupiter), giving us some nitrogen gas back (we can reclaim the oxygen from the water with electrolysis or high-temperature cracking, but neither are an efficient process). Any oxygen release into the Jovian atmosphere is likely a total waste; the resulting water will be denser at any ambient pressure than anything else around it until the supercritical steam reaches the solid core of the planet, composed of everything Jupiter's Hoovered up over the eons. And you're 630 million miles from the closest breathable natural atmosphere in the Solar System, at the very closest; when Earth and Jupiter are on opposite sides of the sun, you're a couple billion miles from anything readily breathable. There is some good news; Jupiter's moon Europa is an ice ball, completely covered in water ice (very likely with a liquid water ocean under that), and it's the second-closest major moon in orbit to Jupiter, so it's a relative hop-skip-jump out of the upper Jovian atmosphere compared to getting anywhere else. It would, if we're talking colonization, be a much easier "errand trip" to send ships to collect and bring back some of Europa's water, which can then be drunk, used in hydroponics, electrolyzed to oxygen, whatever use the Jovian colonies have for it. Europa also has a thin oxygen atmosphere, caused by radiolysis of the water molecules of the ice surface by a combination of solar radiation and charged particles from Jupiter's magnetosphere. Compressing that to any useful pressure would likely be a waste of time during a manned mission - the atmosphere is about 1 trillionth the pressure of Earth sea level - but it could be a worthwhile endeavor to land solar-powered compressors that could work for months on end between trips to produce relatively easy-to-use bottles of compressed or liquid oxygen. [Answer] I'm going to consider hydrogen/helium rich warm gas giants like Jupiter and Saturn, here. Things are different for cooler ice giant worlds, so I'll leave those for another day. I'll use "gas" instead of "air" to refer to the planetary atmospheres, and hence "gascraft" instead of "aircraft", etc. --- The biggest problem you'll have with hydrogen-rich gas giants is atmospheric density. Even when the atmospheric pressure is friendly Earth-sea-level like, densities will be a fraction of the density of our atmopshere (which is why hydrogen balloons float up on Earth, obviously). [Lift is proportional to density](https://www.grc.nasa.gov/WWW/K-12/airplane/lifteq.html), which means that wings for use in a gas giant atmosphere are going to have to be pretty big... as a ballpark figure, perhaps 10 times as large, to generate the same lifting force as a wing on Earth. This will only be compounded if you want to live on a huge world like Jupiter, where gravity is already more than twice as strong at the altitude where you'd find Earth-like pressure, so you'll be wanting wings that are more than twenty times bigger! On the bright side though, [drag is proportional to density](https://en.wikipedia.org/wiki/Drag_(physics)). Drag is also proportional to velocity squared, so you could travel at 3.5-4x the speed you might in Earth's atmosphere for the same amount of effort. Lift is also proportional to velocity squared, which means that for high speed aircraft you can make up for the lower lift provided by the thin atmosphere. The speed of sound in hydrogen is also about 4x higher, so you can travel much faster and still remain subsonic. So, take-home message: **no low-speed gascraft that use wings for lift**. High speed gascraft might look more like lower-speed aircraft on Earth. Because winged gascraft will likely be travelling *really fast*, you won't want them going too close to habitats and other facilities for safety reasons. Their bases (gasports? gasbases?) will be therefore well separated. If you're not going anywhere in too much of a hurry, use a lighter-than-atmosphere craft, using the same floatation devices your habitats use. Remember again that the low-density hydrogen atmosphere means low drag, so your zeppelins can travel much faster than they could on Earth. Escape craft, escape pods and parachute-equivalents will also need to be balloons of some kind to either stop descent or delay it for long enough to affect a rescue! I'm not going to attempt to work out the issues helicopters might face. Maybe another time. If your fusion reactors have a good enough power-to-weigh ratio, it may be possible to make vehicles or platforms that can hover and station-keep for extended periods of time using orientable or downward facing jets or fans. This might be a way to allow your super-high-speed winged aircraft to approach habitation safely at low speeds without needing to be bouyant. --- You've suggested metallic hydrogen as a useful monopropellant, implying that in your universe it is *definitely* metastable at sensible temperatures and pressures. *However*. There are a few issues with the substance listed on [Project Rho](http://www.projectrho.com/public_html/rocket/enginelist.php#id--Chemical--Metastable--Metallic_Hydrogen). One of them is that the temperature of a rocket engine using the stuff is *very high* (like, engine-vapourisingly high), and even if you use hydrogen as a coolant you'll still drop your Isp to a mere thousand seconds or so. Not bad, compared to mere chemical rockets, but not really enough to easily get you into space in such a deep gravity well. Secondly, that whole metastability thing. It packs about 50 times more energy than TNT, per unit mass, and you probably don't need to apply much *oomph* to it to make it cook off. Everything fuelled with metallic hydrogen should be considered a bomb (or missile) until proven otherwise, and should be used and parked at a very safe remove from most habitation and industrial facilities. It might not even be safe to use it too close to nuclear reactors, if there's a chance that a stray fast neutron or suitably energetic gamma-ray might push a little blob of the stuff over the energy barrier and into explosive decomposition. Another take-home note: **metallic hydrogen is hugely dangerous, and no-one will want it used anywhere near anything**. --- With regards to space-capability, that's a tricky one, something that's heavily dependent on how massy your gas giant is. But, TL;DR: metallic hydrogen is not going to get you into orbit, even before you dilute it to stop your rockets melting. The first thing to remember is that gas giants are *big*, and to get to the equivalent of Low Earth Orbit where you'll be at least temporarily stable, you'll have to fly up pretty high and that means you need lots of energy. To lift an object from the Earth's surface to a 250km altitude, you need to provide at least 2.4MJ/kg (note: this excludes the energy required to reach orbital velocity!). You need *10 times as much* to reach 1000km over the 1-bar level on Jupiter, and you might not even be far enough above the atmosphere to be able to maintain your altitude as long as you would at 250km on Earth. Orbital velocity at 1000km above Jupiter is ~41km/s. At 1000km above Saturn is ~25km/s. That's a *huge* around of delta-V you'll need, on top of the steep gravity well you're trying to climb out of, and in the case of Jupiter, you'll be needing rockets that can deliver more than twice the thrust of their Earth-equivalents at the same time as lifting all that stuff out. That's a pretty tall order, and might require some seriously powerful nuclear rockets to get you out. An [Orion drive](https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion)) might be worth considering here. Of course, you don't need to orbit; as you pointed out, getting above the atmosphere seems like a good way to cover long distances in a sensible time, if that seemed important. [Boost-glide](https://en.wikipedia.org/wiki/Boost-glide) vehicles are probably what you want there... long, low suboribtal trajectories that skip off the upper atmosphere. The aerodynamics and design of such vehicles will be quite different from either the large-winged fast gascraft or bouyant slow gascraft mentioned above, and trying to combine multiple modes of operation is probably just asking for inefficiencies. Don't compromise; specialise. The environment is already punishing enough without silly designs and unnecessary extra engines and control systems to make flight more inconvenient! --- For chemical fuels (and indeed, for some or more of the elements that you'll need to keep your habitats running) you will have to either a) ship it in from elsewhere (such as the Jovian moons) or b) harvest it from deeper in the gas giant's atmosphere. Jupiter, at least, has ammonia and water cloud decks, which should offer excellent sources of nitrogen and oxygen. You need to drop perhaps 100km below the 1-bar altitude, and the pressure will rise by a factor of ten and the temperature will at least double (which is inconvenient for bouyant vehicles) but it is doable. Other gas giants may also have handy things like methane clouds for carbon sources. [![Atmosphere of Jupiter](https://i.stack.imgur.com/MAruC.png)](https://i.stack.imgur.com/MAruC.png) ([Atmosphere of Jupiter](https://en.wikipedia.org/wiki/Atmosphere_of_Jupiter)) I'd be inclined to use fusion for as much as possible though, as chemical harvesting may well be less convenient that deuterium and helium-3 refining at higher altitudes. The energy densities of chemical fuel are much lower, and there are probably more useful things you could do with the materials than set them on fire. Nuclear ramjets will be able to go pretty fast in a hydrogen atmosphere, and so might be useful for medium-haul travel, if you actually have need of such a thing. [Nuclear jet engines](https://en.wikipedia.org/wiki/Aircraft_Nuclear_Propulsion) might simply be a better alternative, because gas giants are big and interesting stuff will either be close (because that's where you build it) or far away (for whatever reason) and so there may be little need for a middle ground between boost-glide and scramjets and turbines. Up to you, though. --- And as some responses to [KeithS's excellent answer](https://worldbuilding.stackexchange.com/a/167099/62341): * Inert gas is of course readily available in the form of helium. There may be some mileage in your habitats and vehicles having an outer pressure hull of helium at slightly above both internal and external pressure. This makes it easier to keep your hard-to-replace atmospheric gasses like oxygen and nitrogen (and even carbon dioxide!) inside, because they can't simply leak into a higher-pressure buffer. In an emergency, helium can be dumped if it starts leaking into habitable areas, equalising pressures whilst leaks and scrubbers are fixed. It is easy enough to replace. * Building and maintaining a network of JPS satellites is an excellent idea, but for safety reasons you might consider having atmospheric positioning systems too, because if TSHTF it could be very, *very* difficult to fly up into orbit to replace or repair infrastructure. It might even be easier to do some of this stuff on Jupiter because lines of sight at so very long... there's a reduced need for clever over-the-horizon low-frequency things like [LORAN](https://en.wikipedia.org/wiki/LORAN) when it may well be possible to use VHF-based marker beacons, driven by fusion reactors for high power, with vast ranges. After all, gas giants are likely to be sparsely populated, and whilst mobile beacons don't help with global navigation, most navigation is likely to be local anyway and a suborbital hop can point in the approximate direction of another habitat's marker beacon cloud and targeting can be refined as a fix is acquired. ]
[Question] [ **The Setting:** The world is over 99% water with only very small bastions of solid land or ice covered land. The humans who live on this world are very capable swimmers and divers who can hold their breath for a very long time. In general, the people are smart however they are held back from an industrial revolution due to their lack of metal, fuels, and simply because their population is limited by the size of the island. Technological progress has stagnated or for a couple hundred years while theoretical work including math, physics, and philosophy have continued to advance. For example, scholars on the island have a firm grasp of calculus and Newtonian physics but have dismissed ideas of making a steam engine as it would be too expensive and impractical (which is true, they simply don't have the metal or the need). **Technology Level:** The people have wood and other agricultural/biological resources such as fibers and cloth for sails. Metallurgically, the people have somewhat advanced techniques but due to the small size of their island, they don't have a lot of metal. Most of the metal they have is bronze however they also have a large amount of meteoric aluminum. At great cost, artisans can create mechanical clocks and devices but these are reserved for the island's elite. Additionally, the people have quite a good grasp on optics as the nature of their island allows easy glass-manufacturing. Plants with large reflective leaves allow them to make cheap mirrors and reflectors for long range signaling or concentrating sunlight to cook. **The Monsters:** Due to being a water-planet, the land that the humans inhabit has basically no natively-evolved creatures on it and it is very safe. On the other hand, the sea is very dangerous. All varieties of massive fish, giant tentacled beasts, or venomous jellyfish can be found there and occasionally attack ships. The largest creatures are big, think kraken-attacking-pirate-ship big. **The Rationale:** The people, besides needing to travel between their tiny bastions of land, rely on the sea for a large amount of their resources. Fishing is very popular along with trapping (like lobster traps) and diving to harvest underwater plants and resources. Additionally, there is a high cultural drive towards exploration as finding new lands to support the growing human population is seen as important. **The Question:** What features might a sailing ship include which helps the crew fight against frequent monster attacks or make their travels across the dangerous ocean safer? For example, * Sharpened wooden spikes lining the outer edge of the ship's hull to combat giant tentacle attacks * Barrels full of dead fish that the crew can throw overboard to distract any predators * Listening posts or portholes below the waterline of ships where specially trained crew members can listen or watch for incoming monsters [Answer] There are many things that you can do to protect a ship at sea, but they're not all what you might think. ### Copper coated hulls Teredo navalis is a very small sea monster, but utterly destructive of wooden ships in the long term. It's one we have here as well and there's no reason to make it any more dangerous than it already is. Creosote also works. ### White paint Start thinking like a fish, many of them are dark on top and lighter underneath, this is to allow for the different light patterns and gives basic camouflage. ### Streamlining Faster ships are good, but we're still trying to reduce our visibility. A better streamlined hull will be quieter and not attract monsters from such a large area. Any spikes or other heavy defences on the hull will have the opposite effect. ### Hydrofoils Taking this to the cutting edge of what you might be able to pull off with your technology level. Sailing hydrofoils are a thing, if a little fragile, and could potentially allow a small vessel to outrun anything that might cause it trouble. ### Sticking to known shallow waters or very deep waters Octopodes are ambush predators, keep away from waters that provide cover for a large kraken-like creature and keep moving fast. You're mostly vulnerable when passing over underwater crevasses in moderate water depth. If you have access to a gently shelving sea floor there won't be any cover for such a predator. Very deep waters are basically the deserts of the ocean, there's very little out there. The most dangerous places are the best fishing grounds. Places where the sea floor shelves up steeply driving deep water currents to the surface. Such locations will have the most food and with that, the most predators. ### Kraken-hide ships With lots of tentacles krakens should be at risk of getting tangled and attached to themselves, but the [nature of their skin and tentacles](https://www.theverge.com/2014/5/15/5720446/science-explains-why-octopus-arms-dont-stick-together) means they don't. Coat/make your ships with kraken skin and they won't be able to attack. [Answer] Here's an interesting question I'd like to ask: Why should a ship have to float on the water? What if it floated..... in the sky? Your civilization has the technology for fabrics and textiles-- why not make a hot air balloon? If you can successfully sail high enough in the air (which is probably not that high) you could safely avoid any sort of sea monster! The drawback here is obviously that you're going to see hugely reduced cargo capacity relative to something like a ship-- but you'll also be significantly safer. You're also more at the whim of the weather-- if you run into a storm, or if you miss-calculate something and fly too high or low, it could end very, very badly for you. I understand that I may not be fully answering your question, as you probably want to incorporate some of the dangers that would go along with being on a ship in the ocean having to contend with a bunch of cool monsters. That's fair. The hot air balloon might be a scouting vessel, or a last-resort-life-boat type situation for a few crew members to rush to in the event that the boat is destroyed. (I'm assuming that the hot air balloon is tethered to the ship and just floating there at all times, since it would take way too long to inflate the balloon in the event of an emergency) As for the ship itself-- I think that their best bet is to just avoid being attacked in the first place rather than fend off the attack. The best way to do that is probably to follow in nature's footsteps: Pretend to be something you're not. What's the biggest, baddest, scariest creature that anyone has ever found in the ocean? See if you can make the ship look like that beast. All of the smaller monsters will be scared off by it hopefully. Only the biggest, meanest ones are going to come after the ship. And after all, that's only one type of monster, right crew? There's no way there's an even bigger monster that we haven't seen before that would see that one as a meal! Right??? Another option might be poison. If one of your societies could kill something highly venomous (say, one of those giant jellyfish), ships could coat weapons in that venom. If a predator pursues them, it's now a race to figure out how to poison that creature before it attacks! Maybe you put venom on some of the dead fish that you throw it, as you desperately hope that this monster's insides won't like the venom! Maybe you treat the wood with it? Maybe you take along convicted criminals/enemy soldiers and coat them in the venom, then throw them overboard? The world is your extremely deadly oyster! [Answer] Small islands means small trees. Small trees limits the size of your boats, so you will see things much more like islander catamarans and kayaks. People on earth have used these kinds of vessels to travel thousands of miles. That's what you will be limited to. Since we do the best we can with what we have, your best defense will probably speed along with just not being big enough to be worth a really big predators time. You mention your people being very good with math. This is going to help with the speed aspect. Advanced hull designs and streamlining will have these boats moving along very fast. They will also be able to develop precision instruments and accurate charts. This is extremely important. The best way to deal with a predator is to stay away from where they are. Accurate navigation keeps you in the safe water. I imagine your people are going to spend a lot of time studying the creatures that are threats. That includes how to kill them. They might try hard to find toxins that discourage the large kraken like creations. An example would be learning about, I dunno, Sea Urchins. Lots of fish might avoid them because of the pointy bits, others because they have irritants. Coat your hulls with the irritants and those predators might stay away, just like skunks drive away their predators with a good dose of spray. Or make a concentrate of the stuff to dump in the water on demand. In extreme circumstances, you might be able to make explosives. Make those waterproof and you could even create depth charges. These could be made without metal because they rely on pressure waves to kill rather than shrapnel. I know you need charcoal, sulfur, and saltpeter to make black powder. If you island is volcanic you have a good chance of sulfur. Seabirds will provide the saltpeter as guano (on earth we have fought wars over islands covered in seagull crap). The charcoal can come from the unused bits of tree when you build a new boat. I'm not enough of a chemist to know how to make a fuse burn underwater, but that might come from handwavium. Have some fun with it. ]
[Question] [ It's [twenty minutes in the future](https://tvtropes.org/pmwiki/pmwiki.php/Main/TwentyMinutesIntoTheFuture), and farmers across the 'big countries' (USA, Australia, etc) are facing a new scourge: light poachers. Every summer hordes of self-driving trucks crash into fields and deploy vast photovoltaic cloths over the nice flat, clear ground, covering up to several acres of cropland each. The cloths capture the solar radiation to the detriment of the crops growing underneath, and the power (up to several megawatts on a 'good day') is collected by the trucks, and... what? What can my poachers profitably do with up to ten megawatts of free electricity within a volume the size of a shipping container, to either store the electricity to be utilised later, or manufacture something that can be subsequently sold? The factory will have no external connections of any sort other than power in and air in/out, so any raw materials will have to form part of the payload (it would be reasonable for them to need to be un/re-loaded up to once a day). I'll handwave the economic implausibility of the capital cost of these automated factories, or the fact that there are plenty of 'legal' places where such a thing could be set up without trespass. I'd like to avoid the obvious answer of "mine bitcoins", or other virtual commodities, and have the factories produce a physical, tangible product. [Answer] Even better answer thanks to @StarfishPrime They produce nitrate fertilizer out of water and atmospheric nitrate, by using tremendous amounts of power to split and rearrange water and molecular nitrate. Then they offer it to the very farmers, to whom this is a sound proposal actually, as plants are often much more constrained on nutrients than on sunlight. Might need to balance that. [Answer] They make aluminium from clay (Bauxite) and then sell aluminium appliances to farmers. Pots, rakes, utensils, etc. [This process](https://en.wikipedia.org/wiki/Hall%E2%80%93H%C3%A9roult_process) requires tremendous amount of power but not much else, to my understanding. [Answer] They use the electricity to transform water into oxygen which is released and hydrogen which will be the standard fuel of all vehicles '20 minutes into the future'. Hydrogen won't be particularly valuable but used everywhere (including for the trucks themselves). [Answer] **Bitcoin** They will use electricity to mine cryptocurrency. This requires little infrastructure, and resulting commodity is "liquid", meaning they don't have to worry about how to sell it. [Answer] **War profiteers** These megabatteries are much desired by both rebel factions and the underfunded official troops of the country where these sun pirates operate. Megabatteries can power hungry energy weapons capable of amazing feats: microwave antipersonnel actions, frying surveillance drones or even taking down an orbiting weapons platform (it takes several batteries for that). These energy weapons were developed by and for an advanced polity with cheap plentiful fusion energy but that polity is far away (or possibly extinct). In the present place and time, fixed installations for charging batteries rapidly become targets and so the sun pirate strategy is successful. [Answer] They contract their services to the movie and TV industries, and run CGI rendering server clusters (and the necessary air conditioning) in their trailers. No material requirements at all. ]
[Question] [ The population of my world is well fed and water can be plentifully scavenged from the plant life. We live in a wonderful tropical utopia that boasts a large nomadic population. The weather systems are stable and predictable we know when the storms will come and the jungles tell us when they're about to hibernate, people have learned these patterns over thousands of years and travel to keep away from areas of trouble. I as a great seeker of knowledge travel with the few who share my passions and we seek to fix problems we see the nomadic tribes are dealing with. Mostly a lack of recorded history and feel that society has stagnated, there's no passion for innovation! To overcome this shortcoming we feel that the answer is to create a center of learning (hopefully multiple!), but we've come to the problem that the most successful way to store and record knowledge keeps us largely immobile. Which can be helpful since everyone can find us. The problem is now that we don't move around much we have to deal with troublesome weather and times of plight as the jungle occasionally bears less goods to harvest. We who wish to build a new society are few. We need more so we can create stable traditions of learning, and eventually start up reliable trade between multiple centers so that food and water shortages are fewer. *How do we convince nomads to settle down from their lives of ease to live a life of hopefully temporary burden so that our new dream of innovative society can form?* **Notes** * We have little to no metals available, though our tools may allow for better craftsmanship, the materials are going to be the same available to the nomads. * Conflict between nomad tribes is low, they have no need to fight over resources. Other than a few of the nastier predators of the jungle there's not much weight of the offers of protection. It's usually just simpler for them to move on. * The storms are particularly nasty when they come through, collapsing large portions of the jungle with their high winds. * Our world is large, and spreading word to the tribes that we seek settlers has been difficult. Many times tribes don't communicate with others for months or years at a time. Some tribes will never meet again even after decades of travel. * We've assured ourselves that after our dreams come true the burdens we've dealt with will be eased! Surely the ability to make better technologies, accumulate knowledge, and set up trade systems will help everyone! We just have to convince a happy population to burden itself with this dream. **Useful links to other posts about building this world :)** [The "Soil" of the Hanging World](https://worldbuilding.stackexchange.com/questions/160104/hanging-world-soil) [The Trees and Plant life of the Hanging World](https://worldbuilding.stackexchange.com/questions/160097/hanging-world-trees) [Answer] **The nomads do not settle. You do.** [![enter image description here](https://i.stack.imgur.com/Jzo4f.jpg)](https://i.stack.imgur.com/Jzo4f.jpg) <https://en.wikipedia.org/wiki/Saint_Catherine%27s_Monastery> > > Saint Catherine's Monastery lies on the Sinai Peninsula, at the mouth > of a gorge at the foot of Mount Sinai, near the town of Saint > Catherine, Egypt... Built between 548 and 565, the monastery is one of > the oldest working Christian monasteries in the world. The site > contains the world's oldest continually operating library, possessing > many unique books including the Syriac Sinaiticus and, until 1859, the > Codex Sinaiticus. > > > This Saint Catherine's monastery is pretty interesting - holy to multiple religions it would seen. <https://www.sinaimonastery.com/index.php/en/description/the-monastery> A 1500 year old library is pretty cool in and of itself. Like the monastery, your site of learning is built on a holy place and staffed by holy people. The nomads bring offerings of food and supplies and information on their yearly pilgrimage and the monks stock up to get thru the rest of the year. They grow some of their own food too. The monastery has a spring and so is a nice place to rest for the nomads as they travel - it is not a struggle to get them to show up. [Answer] Well hello there, nomads! Sure, you might *think* you're happy now, but... **...try some of this delicious distilled hard alcohol!** Take as much as you like! Come back any time! [Answer] Two possibilities based on two of the prevailing theories on why humans originally started living in cities. **1. Religion** See [Göbekli Tepe](https://en.wikipedia.org/wiki/G%C3%B6bekli_Tepe). Similar to Wilk's answer, start a religious center that doubles as a library. But rather than aiming at total self sufficiency, convince the nomads to makes pilgrimages and sacrifice game to supplement the priests' diet. Start domesticating animals and plants, and recruit the brightest and hardest working nomads to join your elite group living at the complex full time. **2. Alcohol** A more traditional view, as expressed in [A History of the World in Six Glasses](https://tomstandage.wordpress.com/books/a-history-of-the-world-in-six-glasses/), is that humans accidentally stumbled upon the wonders of fermented grains, and domesticated grain to be able to produce larger quantities. This is what Roger's answer gets at. You can also combine these two together; there's a reason monasteries are known for their breweries and vinyards! [Answer] You mentioned it in a comment, but I think one of the most important reasons to settle down is medical care. If only for help during childbirth, this can draw in a lot of travellers, if you're the only site on the world than can provide adequate care. Same for the elderly, who'd be less able to travel as they grow older, and they'd be more suited to "help out" at a nursery type establishment. --- To go into a bit more detail: > > We have little to no metals available, though our tools may allow for better craftsmanship, the materials are going to be the same available to the nomads. > > > Simplemedical implements don't necessarily require metals, especially if you're starting out with just splints, ointments and herbal remedies. Some metal could be useful for small instruments such as tweezers, stitching needles and scalpels (or just any small, sharp knives) that can sterilised and reused. That does however raise some questions about your civilisation's knowledge of microbiology. > > Conflict between nomad tribes is low, they have no need to fight over resources. Other than a few of the nastier predators of the jungle there's not much weight of the offers of protection. It's usually just simpler for them to move on. > > > Conflicts may be rare, but I doubt there'd always be some, even basic feuds. Fights break out between teenagers, pranks go wrong, etc, so medical care can always be helpful. If there are feline predators out there, stitches and preventing blood loss would be major survival factors. > > The storms are particularly nasty when they come through, collapsing large portions of the jungle with their high winds. > > > This could be problematic for a settlement, but if it were dug into the side of a mountain ([native american style](https://dynaimage.cdn.cnn.com/cnn/q_auto,w_900,c_fill,g_auto,h_506,ar_16:9/http%3A%2F%2Fcdn.cnn.com%2Fcnnnext%2Fdam%2Fassets%2F140221153553-unesco-11.jpg)) or sheltered some other way, your settlement would probably be quite durable. You'd probably need some sewage / water evacuation system, but that can be developed once the settlement has started properly. > > Our world is large, and spreading word to the tribes that we seek settlers has been difficult. Many times tribes don't communicate with others for months or years at a time. Some tribes will never meet again even after decades of travel. > > > If your settlement is estableshed close to (or in) a large mountain or other natural landmark which is visible from afar, it could be easy to set up a beacon of some kind to attract attention to your settlement. Once some tribes know of it, they could spread word around to tell others of it. This could also serve as a method of communication between tribes: if there is some form or library / archive in your settlement, tribes could leave messages to another tribe. That way, they wouldn't need to rely on bumping into each other on their travels to communicate. > > We've assured ourselves that after our dreams come true the burdens we've dealt with will be eased! Surely the ability to make better technologies, accumulate knowledge, and set up trade systems will help everyone! We just have to convince a happy population to burden itself with this dream. > > > Once a few tribes have come through and noticed that childbirth / diseases / impromptu surgery go much better when someone does that with all their time, I don't doubt that they'll be incentivised to stay within a week or so of travel of your settlement. And once you start distilling alcohol (for disinfecting your surgical equipment, of course), you'll be sure to convince them to stay. [Answer] There are a lot of ways. I can think of a large coup of methods. * Change from the top. You convince a tribal leader with enough power to settle down. He then can convince people in the long term but for now his authority is enough. We have too many of those changes in history to even bat an eye at it. If your leader has enough power to pull it off until it begins to work then it would be a peace of cake. * Change from the bottom. Not exactly the opposite. You can't convince 99% of the tribe about your plan. Heck. 80% is too much. But all you need is a strong base among the people Just a solid base of rebels and people with strong believes and willingness to work. Like your average revolution basically. You don't need the whole tribe, but if you can it's awesome, because 20% willing to work and do the heavy lifting is better than the 80% that don't want to do anything. From there you either have a dictatorship with your initial group as the ruling class or you can keep things more civil but still enforce your vision. * Show, don't tell. Get your group together. Build your society. And when people show the shining Utopia you have then they will flock to your state. Or you can just conquer them. * There is a lot more variations of these thought. For example if you start convincing the young ruling class of the tribe of your vision then you are setting up a rebellion and a friendly head of state at the same time * And as a last point. I think you will only start getting real results when few can remember that old days. You just have to weather the storm for the first generation then the second generation won't even think about the golden days. [Answer] There is a moral philosophy question. In [Systems of Survival](https://rads.stackoverflow.com/amzn/click/com/0679748164), Jane Jacobs outlines a thesis that moral codes are bifurcated. That is, there are fundamentally two such moral codes that depend on the fundamental method of getting a living. These two are the make/trade method, and the guardian method. The older is probably the guardian method. This consists of staking claim to a geographic territory and extracting value from it. This includes doing so in a nomadic, even transitory manner. So nomads will be using this. Fundamentally, this morality involves at least the implication of the use of force to defend the territory. The other method is make/trade, otherwise known as economic. You make some valuable items. And you trade some of them with other people for things they've made. And you both wind up better off. It's the old story about the people who live by the ocean have a lot of fish and a ready supply of salt. The people in the mountains have flint and bamboo suitable for spears. If they trade some of what they have lots of for what they have little of, they are both better off. In particular, they are better off than if they were to slaughter the other tribe, because the tribe that dies out takes with them the knowledge of their side of the trade. Jacobs outlines the transition of a tribe called the Ik. (Yes, funny name. Please get over it.) Colin Turnbull publishes a description of them during the harshest part of the transition in [Mountain People.](https://rads.stackoverflow.com/amzn/click/com/0671213202) They were nomads. The country's government wanted to make a huge park out of their territory. So they were forcibly settled. Of course, they started with a moral code suitable for nomads. They exerted prowess. They played truly violent practical jokes, especially on people from outside their tribe. They were fatalistic and made little preparation for the future. They were territorial. They followed traditions. They took revenge. They were loyal to their tribal hierarchy, but deeply mistrustful of outsiders. They had little idea of contracts, and were quite pleased to be able to loot somebody else's store of food or other valuables. Then they were forcibly settled and prevented from roaming in their former territory. They nearly died out. About three decades later they are doing OK as subsistence farmers. They are thrifty, industrious, and keep contracts. They cooperate with their neighbors. They are optimistic. They are, compared to what they were previously, non-violent. And they make as much preparation for the future as they are able. They improve their land and their herds, and they store up food for the lean times. So the Ik were forced, by horrible experience, to adopt the moral code suitable for living in a village and farming. This is drastically different from the moral code suitable for nomads in the African bush. So, to get nomads to settle in one spot you need to teach them the moral philosophy of being economic actors as opposed to extracting value from a territory. It's a very hard lesson. Drastically hard. Reading about the transition of the Ik is not recommended for bedtime reading. Some of the events are quite nightmarish. But after the lessons, they are doing quite reasonably for subsistence farmers. And, as a result, they don't want to be nomads any more. [Answer] There is the way as it presumably happened on earth, see for example the all time favorite 'Guns, Germs and Steel'. Essentially, an agricultural society can support a much bigger population per area than a nomadic one. Additionally, farming populations can grow much faster than nomadic groups. In nomadic groups a women can only have a child every 4 years or so, because only then can a child walk with the tribe on his/her own. In a farming society women can have children every 18 months to 2 years (child mortality is super high either way). So start with a small agricultural settlement, the farmers will win out on the nomads eventually by sheer force of numbers. ]
[Question] [ I have been thinking about this for an unhealthy amount of time, truth be told. Simply put, a 4-meter, 8-meter, if stretching the limit, tall mecha, made out of carbon-based synthetic muscles, hyper-strong light materials. Examples such as magnesium come to mind. I'm not a scientist, or an engineer. And I bet a material scientist can think of better materials, much less in a hundred years. Just for clarity, we're talking advanced, but still hard sci-fi. What roles would it be useful for? What roles would it be terrible at? Civilian roles, combat roles. Considering environments, such as space and urban situations. For some reason, I also want to ask if putting thrusters on it would make it go fast, Armored Core style. [Answer] Why is it a terrible idea? Because organic things aren't good at fighting. Humans were built with endurance in mind. We're incredibly resilient. If we suffer scratches or nicks, we can heal them up in a few days. Deeper cuts can be healed and replaced with tough scar tissue after a few weeks. Broken bones? No problem - those can be healed as well. Internal bruising, fractures, and sprains? All can be healed up. The point is that we're designed to be able to recover from repeated minor to major injuries over the course of time. As long as nothing gets detached, and the we aren't killed, of course. That comes at a cost, namely *short term*, something which humans are remarkably bad at, compared to other animals and things like robots. Steel limbs sound great, but they can't be remade if broken without invasive surgery. Similarly, armor can block blows much better than skin can, but can't regrow from nicks and cuts. And it's weight means shorter operating time. So, short term - having solid but unrepairable defense is better, but humans were built long term in mind. And combat is short term. Very short term - a one on one fight to the death can take seconds, especially if side A is built for short term victory and side B is built for long term endurance. Humans aren't built to fight life and death situations - they're built to avoid them or use their big human brain and dexterous hands to manipulate the situation and create tools to give them an advantage - tools that give them short term advantages, like weapons, armor, and tools. In other words, humans aren't built for combat, and anything designed solely based on the human physique is just subpar for combat because the same materials could be used on better designs. That aside, you run into issues like the square-cube law, meaning that building humans to scale for double or triple their own size is almost impossible because it needs materials with a strength that scales exponentially. [Answer] **Your mecha would be a fine synthetic body for a human mind.** When it comes to motor functions, our brains are used to things being laid out a certain way. You want to walk, you effortlessly trigger the correct muscles in sequence and degree, and off you go. No machine would be laid out the way are bodies are, with muscles hooked here and there along bones. Our bodies are the product of long evolution and many intermediate steps. But they are what we have. If you had the tech to move a mind into a synthetic body, Avatar-style, it would be nice if the unconscious found everything laid out the way it liked. You could walk away, scratch your bum, do high kicks or whatever else you wanted in your new body, using your mind as the pilot the way you have since you were born. It sounds like your fake muscles mecha is a synthetic giant human body, ready for a human mind to move in. [Answer] Expanding on [Halfthawed's answer](https://worldbuilding.stackexchange.com/users/64961/halfthawed): # Specialization is Powerful Why isn't a morningstar carved like a human fist, since a fist is good at punching? Because a morningstar hits harder than a fist can. Millennia of combat refined weapon designs *away* from human-oriented designs, because humans are versatile. Versatility is good, but something specialized for its task will outperform the versatile option every time. If you've got a power source sufficient to drive a mech, it will be able to drive a tank much more efficiently, and have power to spare. If you have materials that are strong enough to build an eight-metre mech, you can layer more armour onto an APC instead. I should also point out that a magnesium alloy is a *terrible* idea for a combat vehicle, because [fire is generally a hazard in combat](https://www.sciencedirect.com/science/article/pii/S0010938X11004811). Now, that said... Building a mech would be useful for the same reason that building the [Tsar Bomba](https://en.wikipedia.org/wiki/Tsar_Bomba) was: to demonstrate that you can. "Look at how good our military science is," boasts the country fielding combat mechs to occupied territory. "Look at how many resources we can waste on this!" So you touched on the real reason one would build one of these things in your question - it would be *scary*. It would be a demonstration of how advanced the technology of an occupying force is, and might help cow the populace. But if two countries are at equivalent technological levels, and one fields mechs while the other fields tanks and drones, the latter's going to be the winner. [Answer] Well it depends on the role you plan to use the unit in. As is I would keep mecha around 15ft (4.572 meters) tall for a large one on average,max of 20ft (6.096 meters) if pushing it and keep them between 8-15ft (2.4384-4.572 meters) tall ideally. Use them for built up urban warfare where tanks are non-viable,rapid response forces, military police service (very intimidating and well armed for security),are highly modular ideally to fit a wide variety of roles,can be used more instinctively due to similar body plan and if using a neural link can be even more effective. Don't expect them to fight tanks. Not in a head on confrontation,it'll be like an IFV (Infantry Fighting Vehicle) or APC (Armoured Personnel Carrier) trying to duke it out with one. Sure you may have more heavy armaments than an IFV depending or be more maneuverable in three dimensions;but the tank will have thicker armour,heavier armaments and more ammo for those armaments. Mecha will be more prone to mechanical failure due to the amount of moving parts; especially in the joints and will suffer from wear over time due to the stresses from the artificial muscle. This is to be expected however. When a tank is tracked it can't move without repairs. A mecha can crawl with one leg or drag itself along with none. However the fall will be harmful to the occupant. There are pros and cons,this argument has run for a long time for tanks versus mecha. I always solve it by just not using mecha as tanks. They are closer to a ground based helicopter gunship,lots of guns,very maneuverable,hit hard,but can't take the big hits very well. This can be alleviated to a degree with better armour and sloping;but it will always be an issue. Honestly,I'd say it's not a matter of if it's a terrible idea so much as how the idea is presented. I hope this answer was helpful to you. [Answer] **Don't scale up, scale down** The problem with giant mechs is that they are basically just expensive tanks with lots of weak points and wasted mass, but mini-mechs would offer a wide range of advantages. By mini-mech, I am referring to a military purposed android in the 1-1.5 meter tall range. In this case, your mechs are not designed to compete with tanks, helicopters, and artillery. They are made to compete with infantry, field technicians, etc. **Advantages:** * Robotic parts can generally be made stronger than human muscles meaning a child sized android could carry just as much armor, supplies, and firepower as a full grown man. * Bipedal anatomy and small size means it could infiltrate any location enemy personnel can hide. They can enter buildings, climb stairs and ladders, crawl through caves, operate a mouse and keyboard, etc. * Small size means a smaller hitbox. They will be harder to shoot than a full sized man or larger mech. * Mechanical sensors and computer driven processing means better vision, hearing, precision, and response time than a human soldier. Even if it does not physically move any faster than its human counterpart, its electrical circuits could detect and process an entire combat strategy in the time it takes the chemical circuits of the human brain to recognize a threat; which they can do from distances that human senses just don't work. This means that they will almost always have the initiative advantage. * Uploadable skills. A human must be trained. An AI must be trained too, but once trained it can be duplicated to other androids. This means that if your Field Medic gets shot, you can simply upload the field medic plugin to one of your combat mechs and you have new doctor. * Simpler support requirements. Sending troops in the fields means sending food, water, cloths, medical supplies, shelter, etc, etc, etc. Androids only need a source of power, their combat gear, and maybe some spare parts. They can also be turned off and put in crates instead of housed and feed. So in the space you can house and supply a single soldier, you could pack several androids. * Hostile environments. Robots can survive where people can not. This means they can keep fighting in the vacuum of space or battle fields that are contaminated with radiation/bio weapons, or places too hot or cold for people. * More expendable. The biggest enemy of war is a disillusioned populius. When the news comes back saying that 1000 soldiers died in a battle, the widows, orphans, and parents of those casualties suddenly want to end the war at any cost. But when news comes back saying that 1000 androids were destroyed in battle, a few people might get upset about the economic implications of replacing those losses, but the general population won't demand sweeping changes because of it. If your goal is to retain human control over them (more mech, less android), then treat them like drones. The best case scenario would probably be a remote human operator who defines mission parameters, designates targets, and monitors their progress, while the on-board computers worry about the intricacies of motor control, targerting, reactionary actions, and skill execution. In this capacity, it would be the androids fighting the war, and humans would be the unseen "officers" coordinating them behind the scenes. [Answer] A mecha like that would have civilian purposes in less developed regions. Say a machine that cuts wood needs a lot of space and maneuvering to get to where it wants on rough and uneven area's, while a Mecha can be used intuitively by the operator. Climbing, crouching, ducking the Mecha can do it, and the operator can then use the hands of the Mecha in the same way humans do as an omni-tool. For combat the Mecha's arent likely to be able to stand up to tanks in direct engagements. But in indirect engagements they will reign. Think of urban environments where tanks are at a disadvantage, or fighting through forrests where heavy equipment normally is mostly useful on the road but too bulky for the forest itself. But as mountain warfare brigades they would be best. In mountains infantry is king, as any vehicle has to use the limited roads available where they are vulnerable, easily identified for artillery attacks and easily stopped or destroyed through mines and demolitions. But a Mecha could avoid the roads, it would be a perfect infantry support tool to bring supplies and firepower over terrain that tanks and other combat vehicles cannot cross. For weapons you can look to solutions we have on combat helicopters where the recoil cant be allowed to destabilize the craft or push it off-course too much. Mecha's could also be used in trench warfare. A tank in a defensive position needs to drive up to fire, then down again. A Mecha could be crouched, then pop up to fire and crouch again to relocate. I would suggest using spider-Mecha's though. 2 legs is far too risky, especially since these vehicles have a higher chance of failure. Using a setup similar to combat vehicles like the Striker where with 4 of its 8 wheels intact it is still able to get to safety a Mecha could function better across various terrain and be able to deal with damage or failure of its limbs better. Legs are also easier to armor than wheels and tracks on top of the fact that their discontinuous nature makes them harder targets. "Just shoot the vulnerable legs" is often a way people hope to end Mecha discussions but in real warfare anyone shooting at the legs other than the hipjoints would be court-martialled for endangering his group and not firing at the main body where you can damage both the legs and other vital parts.. For material, hope that Graphene becomes a thing to surround your mehanics in. [Answer] Mechas are pure sci Fi. When it comes to artificial biology though your on the right track. I've been trying to see if limpet teeth contract from heat like fishing line and spider silk would. Haven't gotten there yet. Limpet teeth would make excellent bones though. For artificial muscle use electrothermally operated fishing line that is grown with synthetic life or microbots. It has super low efficiency, but a body wide lung for coolant can regenerate around half the heat for reactivation to be around 40% efficient. In comparison naturally occurring muscles are about 20% to 25% efficient. So an artificial humanoid the size of the Mecha in question can be made and grown and self repaired using either synthetic life or microbots, but using them for war is silly. It would just be for mind uploading to have genuine giants without dealing with the square cube law. The square cube law still exists of course but the strength to weight ratio and efficiency makes it irrelevant at the sizes you mentioned relative to human bones and muscles at the same size. Since the fishing line is 100 times stronger then human muscles for the same size, someone with muscle size able to bench 200 pounds would now bench 20,000 pounds. Scaled up to your Mecha with big muscles and your well past Luke cage territory. Not as tough though. No such thing as bullet proof,just bullet resistant. While a single tank would be better then a single Mecha, being able to grow or 3d print the mechas en masse then insert copied minds though not the original as Cannon fodder could be rather effective. Limpet teeth is goethite nanofibers in a protein matrix. Goethite is an iron compound. They are 7 times stronger then bones. I'm unsure of the efficiency of spidersilk as a thermally activated artificial muscle. Limpet teeth are stronger and if they were to contract from heat they would be better but I'm still unsure. Pound for pound the fishing line artificial muscles have a better power to weight ratio then jet engines and tanks tends to be powered by turbo jets. So you'd have the speed advantage, the terrain adaptability advantage but the height would be a con as would overall toughness. A big gun mounted on shoulder would work, but a tanks low center of gravity and large mass would make their guns bigger and adder without falling over. Put too much weight on your Mecha and they will sink into the soil. Put them on a flat road and they lose the speed advantage over just about anything with wheels. Hope this helps. ]
[Question] [ This is my first question here so I would like to apologize if this is sloppy or in the wrong place or the like. I have searched and found nothing that answers the exact question I think, so thought to ask. I also apologize if the tag is wrong as well. Let's just hand-wave the heat issue of stealth in space for the sake of this question. The nation this question pertains to uses Nanocarbon tubes to turn the waste heat into what amounts to the background radiation of space or the energy used by the opponent's sensors. Anyways, now that that's out of the way, here's what I'm looking for and the like: Could one propel a ship using air pressure or through similar means without having to power up or the like to do so? If yes, I would like an explanation, same for if not. EDIT: Yes in space, sorry for not clarifying. [Answer] Technically, yes. Newton's Third Law is not suspended for compressed air. And indeed, this is pretty much exactly what a [cold gas thruster](https://en.wikipedia.org/wiki/Cold_gas_thruster) does--it's just a nozzle attached to a tank of pressurized gas. But practically speaking? Absolutely not. The energy densities are just way too low. Sure, you can use a compressed air thruster for fine adjustments to attitude and docking alignment, but you won't be managing any significant orbital transfers with such a device. [Answer] As others have pointed out, you can move yourself in space using compressed air. However, it is unacceptably inefficient. You wouldn't actually be able to appreciably accomplish any goals. One of the most important measures of a fuel is [Specific Impulse](https://en.wikipedia.org/wiki/Specific_impulse). Specific Impulse linearly related to exhaust velocity, and it will be easiest to talk in terms of exhaust velocity because its tangible. The space shuttle SRBs have an exhaust velocity around 2500m/s. LOX/LOH engines can get up to 4400m/s. Ion thrusters, known for their efficiency, get to 30,000m/s or faster. Compressed air exiting at the speed of sound clocks in on the order of 300m/s. So it's 1/10th as efficient as the engines we use today. The limit for Nitrogen gas is around 730m/s, so you should expect your thrusters to produce on those ranges. Of course, this gets worse, thanks to the [tyrany of the rocket equation](https://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation). Another key feature of space travel is the mass fraction -- this is how much of your mass is your payload, versus how much has to be fuel. The equation is $\Delta V = v\_e\ln\frac{m\_0}{m\_f}$, where Ve is the exhaust velocity. A mission that requires some quantity of delta\_V to accomplish requires a mass fraction to match. If you have 1/10th the effective velocity, you have to have a smaller mass fraction on the order of $e^{10} =22026$. If you've got engines closer to the theoretical maximum, you're going to be on the order of $e^4=42.598...$ or $e^5=148.413...$ worse mass fractions. This means that to move any given payload via air pressure rather than chemical rockets, you need to have a rocket that's literally hundreds or thousands of times larger. That's why we don't see them used for large maneuvers. [Answer] It would be stealth**ier** because it wouldn't show up in visible light, as much, compared to external combustion. But you could still see it in infrared. Barring extreme metamaterials that just straight-up make you magically invisible, [there's no stealth in space.](https://www.youtube.com/watch?v=xvs_f5MwT04) [Answer] Gases do cool on expansion, so stealth is possible. But you can't conceal the movement itself. I believe automated watch for all detritus nearby will be standard on spaceships, using radar lidar etc. Any unexpected movement will cause an alert, regardless of whether there is thermal signature or not. So, the answer is, no. ]
[Question] [ First let me preface by saying this question will be very math heavy, and might be as equally suited to math stack exchange as world building. For that I apologize, but since the reason for my question is world building, I've placed it here. In the Universe I'm trying to build, there is the Mundane world (where humans live and things more or less follow the set, natural laws of physics), and the Divine world (where Gods live, and things are slightly less rigid). Both worlds are "infinite," but the Mundane world is still "bounded" by the Divine world. This is where the problem with my definition begins. If both worlds are infinite, how can one be "bound" by the other (as in contained or embedded within)? In math, there is the concept of countable and uncountable infinite sets, and, quite non-intuitively, one infinity can be "greater" than another infinity, or can even contain that infinity entirely. I'm looking for a similar concept for my Mundane and Divine spaces, in other words, the Mundane, physical universe is infinite, and yet, still contained within the larger, "more infinite" Divine universe. The first idea that I thought of, and which I'm sure someone will offer as an answer, is to simply embed our 3-dimensional physical universe (Mundane world) into a "higher dimensional" spiritual universe (Divine world). But this feels like side-stepping the real question and seems very much like a cheap way out. As such, I won't be giving points for such an answer. I'm not fully ruling out a 4 or 5 or whatever dimensional universe, but such a universe needs to allow a way for a 3-dimensional and infinite "Divine Space" to enclose a 3-dimensional and infinite "Mundane Space." The Universe we know does all kinds of things that seem to "break common sense math," such as [Quantum Renormalization](https://en.wikipedia.org/wiki/Renormalization) and [String Theory](https://en.wikipedia.org/wiki/String_theory) relying on the axiom that the sum of all natural numbers is -1/12, or [Gabriel's Horn](https://en.wikipedia.org/wiki/Gabriel%27s_Horn), which has infinite surface area in a finite volume. Yet all of these strange things are mathematically valid, and in some cases *must* be true given experimental evidence for how our physical Universe works, and I'm looking for a similar approach here. So my question is: **Without simply embedding it in a higher dimensional space, is there a way, mathematically, to describe an infinite space bounded by another infinite space?** **Edit:** Here is a qualitative, though certainly not quantitative (or mathematically rigorous) explanation of a partial approach: Imagine we somehow have an infinite hypersphere, one which contains an infinite 3d volume, and we look at it as a projection into 3d space. When you project a hypersphere into 3d space, you get something resembling two spheres inside each other. In this case, the "outer sphere" is the divine world, with its surface facing inwards towards the inner sphere, and the "inner sphere" is the mundane world, with its surface facing outwards towards the inner sphere. Both surfaces are actually 3-dimensional spaces, and both are infinite, yet in a higher spatial dimension, the outer surface "contains and bounds" the inner surface, with the extra dimensionality of the hypersphere being used to "fold" the infinite Mundane Universe so that it is contained inside the infinite Divine Universe. As an aside, it is trivial to generalize and say a hypersphere contains an "infinite number" of 3d spheres, in the same way a plane contains an infinite number of lines or a cube an infinite number of planes, but this is the "just throw away a dimension" approach I'm trying to avoid, plus in this generalization the 3-d sphere is finite in extent. What we need is, like the Gabriel's horn approach, to come up with a finite space containing an infinite smaller 3-dimensional space, and that finite space itself being able to be embedded an infinite space of the same dimensionality. I'm not sure this makes sense, but then higher dimensional thinking never really does to brains evolved to watch out for lions in 3 spatial dimensions + 1 of time... ^^; Is there a mathematical definition closely resembling what I've described? **Edit2:** As another aside, perhaps to give some background which may help in coming up with a more satisfying answer, the thought experiment which triggered my asking this question in the first place is this: In my story, the Divine world and Mundane world cannot interact directly, and must do so through an intermediary "quasi-world" which allows one to pass between them. This lead me to asking the question that, in this quasi-world (which resembles a forest but has a sky and sun), if you took a rocket and flew straight up, how far would you go and what would you see? Assuming you found you were on a planet, how far would space in that quasi-world go? This further lead me to asking, if the Mundane World necessarily had to be contained within the Divine World, how could you ensure the Mundane World is infinite, yet still contained within the Divine? Presumably the point at which they join would be the quasi-world, and this would be finite, but the two worlds themselves would also be infinite, with the Mundane contained within the Divine. [Answer] Mathematically you are indeed solid, take an infinite set from an infinite set and it remains infinite, counterintuitive but that's because we deal with concrete numbers of stuff in our everyday physical existence, infinity is hard to grasp from that perspective. In terms of three dimensional spaces your initial infinite space (the Mundane world) must be a folded space like Gabriel's Horn. The second infinite space (the Divine) can however be described relatively simply, it's an infinite plain surrounding the mouth of that Horn. The one space is infinite in living space while still being finite enough in volume to be surrounded by a space that is simply and truly infinite in volume. [Answer] In math one infinite set of numbers is larger than another infinite set of numbers, when you can propose a way to count every number of the second set, without using all numbers of the first. Or proving that even when every number of the second set is used, some numbers of the first set are still unaccounted for. For example say you would like to show that all rational numbers are larger than all natural numbers. You'd count: 1 for 1, 2 for 1/2, 3 for 1/3, 4 for 1/4 etc. As you could use all natural numbers and still stay between 0 and 1, you can fit a one dimensional infinity into another one dimensional infinity. For three dimensions, it could get tricky to make sense of it. Maybe the divine space has a bigger [Planck length](https://en.wikipedia.org/wiki/Planck_length)? EDIT: So you would spin the analogy further by using 3D coordinates. So the coordinate (0,0,0) in the mundane universe would have the coordinate (0,0,0) in the divine universe. And (2,1,1) has (1/2,1,1) etc. In general (x,y,z) of the mundane universe has the coordinate (1/x, 1/y, 1/z) in the divine world. Simply the mundane world is quantified, which means it has a minimum spacial length, the plank length, and the divine universe is a continuum, like the irrational numbers. So in between (0,0,0) and (1,1,1) of the divine world, the entire mudane universe, no matter of its size, fits. (Maybe the first three paragraphs here make it a little more clear on how to image it: <https://en.m.wikipedia.org/wiki/Loop_quantum_gravity> This would describe the mundane, our, universe) [Answer] > > It doesn't really impact the story that much, at least what's written so far, but depending on the answer it could guide future developments in the story (such is the point of world-building after all). The closest thing that's happened so far is that the god explains to her divine human counterpart that the Divine and Mundane realms can't interact directly, and must do so through an intermediary "quasi-world" that allows one to pass into the other. Presumably the quasi world is finite somehow. Really what triggered this question was a thought experiment in that quasi-world (which resembles a forest but has a sky and sun), if you took a rocket and flew straight up, how far would you go and what would you see? Assuming you found you were on a planet, how far would space in that quasi-world go? This lead me to asking, if the Mundane World necessarily had to be contained within the Divine World, how could you ensure the Mundane World is infinite, yet still contained within the Divine > > > So, I'm no mathematician, but I am a philosopher so I'm going to try and answer the question strictly from that perspective, in terms of how it's going to impact reality for your characters. If I'm following the above description, then yeah, the Gabriel's Horn is the simplest way to describe it; e.g. infinite in some dimensions, but not in others. In this case your Gabriel's Horn would be a four-dimensional shape, with 'volume' being replaced with the fourth dimension. In a PRACTICAL sense, the result of this containment (I think) would be that from anywhere in the Mundane world, you could pass through the Quasi-world into the Divine, but the reverse would NOT be true. E.g. you would have to be in certain specific places in the Divine world to pass through the Quasi-world into the Mundane, and passing from the Mundane into the Divine could only result in you arriving in those same specific places. [Answer] So there's countless ways to do this in mathematics, but my personal preference is to build up a world as discussed by Dan Willard. I offer it as an answer here because it has what is, in my opinion, the most interesting way of embedding infinities I have run into. In his paper, [Self-Verifying Axiom Systems, the Incompleteness Theorem and Related Reflection Principles](https://pdfs.semanticscholar.org/c278/147b7a68385836a90939a175a9959cabbf0b.pdf) he explored self referential systems. These are systems which can describe their own behavior. This is a really desirable trait, because it means the universe can be truly understood by an individual within it. Unfortunately, there's a problem if you want to *prove* everything in the universe. A peksy little set of theorems known as [Gödel's incompleteness theorems](https://en.wikipedia.org/wiki/G%C3%B6del%27s_incompleteness_theorems) raise their ugly little head. They show that if said universe can prove all of the truths in arithmetic (i.e. can prove that 2+2=4), and are self referential (you can use the system to prove the rules you used to prove 2+2=4), that the system has to be inconsistent.† This has been a bit of a pest for philosophers and mathematicians. It's desirable to be able to prove everything *and* have all of arithmetic be true. Gödel kind of rained in that parade. Dan Willard explored systems which contained all of the truths in arithmetic as we know it *except* for totality of multiplication. Normally we assume that if I have two numbers *a* and *b*, then *a\*b* is also a number. He explored what happens if you remove this assumption. It turns out to be enough to let you build a universe which starts from an infinite set, and divides and subtracts down towards 0 and 1. You can then use that to prove everything in his arithmetic, and indeed prove everything in the system. By relaxing that one rule, he sidestepped a particular step in Gödel's theorems (diagonalization, if you're curious), and made a self-referential system which could prove its own consistency and contain all of arithmetic (except totality of multiplication). So why do I bring this one up? Well, there's a really interesting curiosity that comes up when you explore these systems. They can be created *within* an existing proof system. For example, we can take a system which proves arithmetic as we know it, and construct a "Willard World" inside of it --- a self-referential system which can prove all of its own statements, and all of this relaxed arithmetic. To do this, you start by constructing a countably infinite set. You then use this set to construct the system. The funny thing is that there are some countably infinite sets which, when you are done, are *provably* uncountable within the self-referential system. So you have a construct which is provably uncountable to entities defined within the system, but which is provably countable to entities which are above the system, even though the construct is the *exact* same construct. This means that there are cases where an entity inside the system sees something which cannot be attacked via mathematical induction, but a "deity" on the outside can see the mathematical induction and prove it without trouble! (In particular, these strange patterns show up when one tries to prove whether you can construct two numbers which, when multiplied do not yield a number). I am reminded of when the Buddha challenges the Monkey King in Journey To the West: > > The Buddha said: > > > > > > > "I will make a deal with you. If you can somersault out of my right palm, then I will let the Jade Emperor give you his power; > > otherwise, you will have to cultivate for thousands of years on > > Earth." > > > > > > > > > Looking at the Buddha’s palm, which was no more than a foot in length, > the Monkey King smiled to himself and hastily said: “Are you sure you > can handle this?” The Buddha said: “Yes.” > > > So the Monkey King stood in the middle of the Tathagata’s right palm, > feeling that the palm was no bigger than a lotus leaf. He did one > somersault and kept moving forward until he saw five huge pillars. > > > He had surmised that he had reached the end of the Heavens and to > prove his trail, he urinated at the bottom of the first pillar, pulled > out one of his hairs and said: “Change!” He then changed the hair into > a big brush and wrote on the middle pillar the words: “The great Sage > as high as Heaven visited here.” Th Monkey King returned to the centre > of the Buddha’s right palm with another somersault and shouted to the > Buddha: “I left and returned; you should now let the Jade Emperor give > me his power.” The Buddha said: “You monkey, do you know that you are > still in my palm?” > > > The Monkey King said: “You just don’t know that I went to the end of > the Heavens and found five red pillars. I left a sign there. Do you > dare to go with me to check?” > > > The Buddha said: “There is no need for me to go and check; you just > look down and you will see.” The Monkey King looked and found that on > the middle finger of the Buddha’s right hand, there was a line of > words: “The great Sage as high as Heaven visited here.” And there was > also a strong smell of urine in the Buddha’s hand. > > > The Monkey King was very surprised and said: “How can this be. I wrote > these words on a pillar that supports Heaven, but how can it be on > your finger? No, I don’t believe it. It is impossible.” The Monkey > King tried to escape from the Buddha’s hand, but he turned over his > palm and changed his five fingers into a mountain of the five elements > of gold, wood, water, fire, and soil, and suppressed the Monkey King > under the mountain where he remained imprisoned for five centuries. > > > ([abridged source](http://www.visiontimes.com/2016/11/02/famous-chinese-legends-the-story-of-the-monkey-king.html)) > > > † *This is a very informal wording. For the airtight wording, please refer to the explicit mathematical phrasing Gödel used.* [Answer] As a couple of the comments hint at, it's difficult to give a precise answer to your question because it's using vague terminology. Mathematics is a stickler for precision, so I'll give a couple of possible interpretations to your question: **Embeddings** I know that you were looking for answers other than embeddings, but I believe you likely have a somewhat incomplete knowledge of what the word means in a rigorous mathematical sense, so I think it would be illuminating to delve into the subject in more detail. [Embeddings](https://en.wikipedia.org/wiki/Embedding), as wikipedia assures us, are structure preserving injections. What the hell does that mean? Well, in the modern formulation of mathematics, everybody loves to build stuff out of sets, which for the purposes of this discussion are just collections of objects (although it can get considerably more complicated if you delve into the [details](https://en.wikipedia.org/wiki/Zermelo%E2%80%93Fraenkel_set_theory)). They like to do this because they're powerful, yet have a remarkably intuitive feel (a set is just like a bag of mathematical objects). Now, sets are all well and good, but what we'd really like to do is establish relationships *between* sets! For instance, it certainly seems like the sets {0, 1} and {a, b} have something in common, doesn't it? But neither of them have any elements in common, so how could they be anything alike? This is where functions come in! Without getting bogged down in the actual formal construction of a function, they can simply be thought of as little machines where you throw in an element from one set, and a *unique* element from the other set pops out. This uniqueness is important-- if we call our function $f$ and denote the value that $f$ spits out when $0$ is thrown in by $f(0)$, then $f(0)=a$ and $f(0)=b$ are both valid function values, but we can't have $f(0)$ be both $a$ *and* $b$. Now, an *injection* is simply fancy math speak for a function where every different input spits out a different output. For instance, if our function $f$ goes from $\{0,1\}$ to $\{a,b,c\}$, denoted by $f:\{0,1\}\rightarrow\{a,b,c\}$, then $f$ defined by $f(0)=c$, $f(1)=a$ would be an injection, while that defined by $f(0)=f(1)=b$ would not. From this example, it should already be clear how injection provides a sense of a space fitting inside another one. A related object is called a *surjection*, which instead refers to a function where every member of the target space pops out of the function given *some* input (it could happen for multiple inputs). Astute readers may note that it is impossible to construct a surjective $f$ with the input and output spaces described above. As a final piece of terminology, a *bijection* is a function that is both surjective and injective. Bijections determine what sets are "equivalent" to each other in a precise way-- sets that have a bijection between them are said to have the same *cardinality*, which is a fancy word for size. This is the precise mathematical description for how {0,1} and {a,b} from above are similar to each other. As an important aside, for finite sets, we have the nice property that if there is a non-surjective injection from one set to the other, there can't possibly be an injection going the opposite way (this is much less surprising than it might sound, just look at the example from before). But this isn't true for infinite sets, which is why you hear all sorts of weird results like the rationals being the same size as the natural numbers. So simply having a non-surjective injection between the two states is no longer enough to guarantee a notion of one space "fitting inside" another space. Now, there are different cardinalities of infinite sets, but most of the time when physicists talk about one space fitting inside of another space they're talking about spaces of the same cardinality. The distinction we're missing here is the *structure-preserving* part of the definition. Let me level with you-- sets are kinda bland. I mean sure, they're useful as building blocks, but by themselves they just kind of sit there. When physicists model the world, they like to have lots of structure to the spaces they use, because the world has lots of structure. These spaces can have all sorts of stuff defined on them, from notions of closeness, to an order, to operations that take two elements and spit out a third. When you require that an injection preserve the structure of these spaces, it severely limits the number of functions that can be created, and gives you a much more meaningful sense of a space "contained in" another space. For instance, there are plenty of injections from 3-d space ($\mathbb{R}^3$) to the plane ($\mathbb{R}^2$), but there are none that preserve the linear structure of euclidean space. The important thing to note is that this concept of embedding need not be applied only to vector spaces, like you seem to implicitly be assuming. To name a few possible types of spaces: we could have metric spaces, topological spaces, groups, or smooth manifolds, which give rise to the structure preserving maps known as isometries, homeomorphisms, homomorphisms, and diffeomorphisms, respectively (nitpick alert-- technically most of those are the names for *bijective* structure-preserving maps, but embeddings are bijective if you only look at the image instead of the whole co-domain). Don't worry if you don't know any of those words-- I just wanted to give you a sense of the incredible richness of embeddings. **Boundaries** To be honest, I find embeddings to be a much better sense of a space "containing" another, but I figured I'd include a brief discussion of boundaries since you mentioned gabriel's horn. Boundaries hail from the world of topology, which is essentially the study of having a sense of how close stuff is to each other but without being able to measure actual distances between points. More or less, the boundary of an object is the collection of points that you get if you take a bunch of spheres and shrink them down as small as possible and then only keep the ones that never fully resided inside the object or outside it. This should be taken with a grain of salt, since a sphere isn't a concept even defined in general topological spaces, but I believe it gets the point across. I suppose you could say a boundary "contains" an object, but it'd be more in the sense that the crust of a loaf of bread contains the bread, as opposed to the sense that the universe contains a loaf of bread. [Answer] Two points: 1. Why can't they just border each other, each infinite in one direction, but not the other? If you split a line into two days, each is still infinite, but they do connect. The downside of this is that there would be one giant wall in space where people could pass through, but nowhere else. 2. What about, rather than having the human world embedded in the divine world, have both of them embedded in a 4D world, one lying "atop" the other in the extra dimension. Imagine laying one sheet of paper on top of another. Would this work? 3. One final solution. Just say "F\*ck it, we're dealing with a deity, presumably the entity from whom all logic and mathematics originates. They can screw with the rules of math as much as they want." [Answer] **The mundane is one facet of the infinite facets of the divine.** 1: I walk down the street. I enter the store. I buy a cup of coffee. 2: I walk down the street. I hear my footsteps. I smell something good; a tree in flower. I enter the store. A young man looks up. I buy a cup of coffee. I note the barista gives me the second cup down from the stack. 3: I walk down the street. One sock is not on straight. I hear my footsteps, and a lawnmower in the distance. A bird is singing above me. I see it and smell the flowers of the tree it is in. I enter the store. The door creaks. I see a childs handprints on the glass below me. A young man looks up, and looks back at his phone, disappointed. I buy a cup of coffee. The barista gives me the second cup. She has a piercing in her ear. 4: I walk down the street. One sock is not on straight, or maybe there is something in my shoe. I hear my footsteps and a lawnmower in the distance; it is my own lawnmower that I lent Boris last week. A bird is singing above me; no - it is a baby bird and it is begging. A parent bird arrives but is slow to feed it. Eventually it does. The tree is in flower. I see the flowers on the grass and the sidewalk; they are falling. I enter the store through the creaking door. I see a child's handprints on the door and I think I know that child; her handprint is from an ice cream drink I saw her get last weak. The young man looks up and then back at his phone. I am not the one he is waiting for. The barista gives me the second cup, full of coffee. She smiles because I come in all the time, and I tip. She has a piercing in her ear that she did not have last week. --- Our mundane world is encompassed in the divine. The space of the mundane is infinite, and the space between your front door and the coffee shop is infinite. The difference between the mundane and the divine is perception of detail. The mundane is one facet of the infinite facets of the divine. No-one, not even gods, can perceive the whole of it. --- An addendum for an OP that wants math. The mundane is unbounded and so has no shape - it extends infinitely in all directions. The divine is within and around it. The mundane is the infinite set of real numbers. The divine is the infinite set of real numbers and the infinite set of decimal numbers between each real number. [Answer] # Math does this all the time, you don't even have to go to great lengths The set of rational numbers "Q" is contained within the set of real numbers "R". Both sets are infinite, but "Q" is countably infinite an "R" is uncountably infinite (therefore "larger"). Some of the neat properties of this relationship are: 1. "Q" doesn't need the real numbers to do basic math operations +,-,\*,/. It's "closed" under these operations. It's only when you introduce algebra that you need the real numbers. This is akin to the normal world being self consistent, but the divine offers something more powerful. 2. The real numbers "R" include all the rationals "Q" but have all the points in between the rational numbers. It's like the rational points are peaks on a mountain range, but the real numbers are all of the mountain range, the valleys, the slopes, everything. And there's a giant who's dancing on the mountain range, who's feet only ever touch the peaks, he doesn't know anything about the rest of what makes up the mountain range, because the peaks are all he interacts with, but really there's much more to it if you were to look deeper. [Answer] I do not like all this questionable "math magic" (you know, Gödel and all that stuff). From phisical point of view: 0) Our "mundate space" **is not infinite** by current scientific consensus. But lets asume plain old infinite Galileo-Newtone universe (with tired light to make skyes dark). 1) **Dark matter/energy/sub particles/some exoctic particles** It IS the divine space and it is embeded or bounded by any phisical partical of our mundate space. 2) **Virtal particles/vacuum quantum fluctuations**. Since there are much more vacuum, then particles volume, it a good place for divine space. And mundate space is truly embeded into divine one. 3) **Quantum time phasing**. Just like single core computer multiprocessing works. You have 1 phase to "execute" mundane world phisics, and 10^N phases for all the divine stuff (or vice versa). Embedment happens in time dimention. It is a good way to justify 1 day = 1 milloin years time pace difference 4) **Virtual reality**. This one is harder and closer to mathematics. One of the universes is [just sort of turing mashine and other is a memory contence](https://xkcd.com/505/) (and a programm) of this machine. Since this "mashine" is infinite and have an infinite memory, second one can be effectivly infinite too. Wich space is wich - is up for you to decide. I ommit vulgar multuverses and multu dimentions, but they are valid variants. ]
[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. **This question already has answers here**: [What would be the tallest possible height for humanlike creatures in earthlike conditions?](/questions/51686/what-would-be-the-tallest-possible-height-for-humanlike-creatures-in-earthlike-c) (5 answers) Closed 4 years ago. How big can a person be while retaining all the functions of all their organs (including bones)? I am wondering if it is possible for large people to exist without compromising some part of their body. If someone invented a scaling machine (for example, Ant-Man), what would be the limit on how big a human could be scaled? Here are the requirements: The human must be able to function like a normal human in an earth-like environment. Being able to function normally means being able to do the following things without additional support or biological changes: * Live * Walk * Breathe * Eat * Sleep * Talk * Think * Do anything a normal person can do Being more susceptible to injury is okay, as long as the injury is not directly caused by the size. For example, falling down and cracking your skull is directly caused by the ground, not by size. The spine spontaneously snapping because of the weight of the torso *is* directly caused by abnormal size. [Answer] The main problem will be the **[square–cube law](https://en.wikipedia.org/wiki/Square%E2%80%93cube_law)**: If you scale something equally in all dimensions, the mass increases as the cube of the scale, while the surface and cross-section areas only scales with the square of the law. This means that if you double the dimensions of a human being, its weight will be octupled, while the muscle and cross sections will only be quadrupled. Each square inch of muscle or bone cross section will have to carry twice the weight. Essentially, this will be like carrying another person on your back all the time. Also, the surface area of the lungs will be quadrupled, while the blood volume will be octupled, meaning that it will be harder to oxegynate the blood. What is the limit that a human could feasibly be enlarged giving this increased strain? This is difficult to estimate, but there is a reason why land animals don't come larger than they are. The largest bipedal animal ever is probably the Tyrannosaurus Rex. The largest known specimen of T. Rex has been estimated to have been about 8.8 metric tons. Given that T. Rex was better built to carry this much weight than a scaled-up human, the limits from the square-cube law may be estimated to about 8 tons. This is roughly 100 times the weight of a 180 cm tall man, meaning that the scale would be the cube root of 100, or 4.64, for a height of 8.35 meters. This being would be able to carry objects weighing 4.64 squared = 21.5 times as much as a normal human could in his hands; say 500 kg. His arms, however, would each weight in at about 6% of the body mass, or 500-550 kg. This giant would hence barely be able to lift his own arms. Other factors may limit the size. For one, the heart would have to pump blood 4-5 times higher, which would require that blood be pumped out at a higher pressure, which in turn would imply a relatively larger heart size. While T-Rex was big, it wasn't taller than 3.5-4.0 meters at the hip - less than half that of our enlarged human. Given these further limitations, I would guesstimate that the largest feasible scale for a human will be at most x4, for a height of 7m20cm, with a mass of 5.120 kg. With a slightly more squat build, call it 7m and 5 tons. [Answer] I'd say the minimum height for the largest human might be 9 feet. Robert Wadlow reportedly had great physical strength until his death. It is important to note he had little feeling in his legs and feet. I would imagine at reaching 9 feet in the 'scaling' process, the subject would experience significant loss of feeling in both the legs and arms. The minimum weight might be ~1041 pounds. Robert Earl Hughes who reached this weight could reportedly walk in a limited capacity. Eddie Hall holds the world record for dead-lifting at 1,102 pounds, so this seems possible. Important note: Eddie Hall almost died once when attempting the dead-lift world record. He burst blood vessels in his head and collapsed. If you are looking for super sniffing power: the largest nose ever is 8.8 cm, held by Mehmet Özyürek. <https://en.wikipedia.org/wiki/Robert_Wadlow> <https://en.wikipedia.org/wiki/Robert_Earl_Hughes> <https://en.wikipedia.org/wiki/Eddie_Hall> <https://en.wikipedia.org/wiki/Mehmet_%C3%96zy%C3%BCrek> [Answer] IMHO it should be possible to double the weight/strength ratio, or cut the strength/weight ratio in half, without too much extra strain on someone. A person of average height who weighs twice as much as an average person would have twice the stress on his muscles and bones. And I know such a man who took walks up to about 8,000 feet (2.4 kilometers) before he lost a lot of weight. Some humans who have twice as much weight as normal persons of their height can function in modern society, even if they would be less successful in a hunter-gatherer society where more activity was required. If someone six feet (1.82 meters) tall weighing 180 pounds (81.64 kilograms) is doubled in dimensions, he will be twelve feet (3.65 meters) tall and weigh eight times as much, or 1440 pounds (653 kilograms). His bones and muscles would have twice the dimensions and thus four time the cross section area as before, and would have to support eight times the weight, and thus have twice the weight stress as before. And if that is roughly equivalent of a man six feet (1.82 meters) tall weighing 360 pounds (163 kilograms), then the double dimension twelve foot tall man should be able to function reasonably well. but on the other hand, it is hard to find evidence to support the idea that a man that tall would function well. There have been a number of men over seven feet (2.13 meters) tall due to their genes, and many of them were quite strong. But most men and women who were extremely tall were so because of abnormal medical conditions, and did not function well, and had health problems. The Guinness Book of World Records lists the Scottish-Canadian giant Angus MacAskill (1825-1863) as the tallest non-pathological giant, and the strongest man who ever lived. He was 7 feet 7 inches (2.31 meters) tall. On a third hand, there are legends of even taller men who were reasonably strong and healthy. The Philistine warrior Goliath was described as "four cubits and a span" (6 feet 9 inches, or 2.06 meters) or less plausibly as "six cubits and a span" (9 feet 9 inches, or 2.97 meters). Georgios Maniakes was a famous eastern Roman or "Byzantine" general in about 1030 to 1043 who was alleged to have been eight feet (2.43 meters) tall. The Roman emperor Maximinus (c. 173-238) was a Thraco-Roman peasant from Moesia (in the region of modern Serbia & Bulgaria) who joined the Roman army and usurped the throne in 235 and was killed in 238 aged about 65. Maximinus was allegedly super strong and eight and a half feet (2.59 meters) tall. On a fourth hand, every human proven to be over 7 feet 7 inches (2.31 meters) tall, and some shorter than that, reached their height due to pathological conditions and most of those were unhealthy and had various size related medical problems. On a fifth hand, there was the Giant of Castelnau. Three bone fragments were excavated in a bronze age cemetery in Castelnau-le-Lez, France, in 1890. They were estimated to be from a human about 3.50 meters (11 feet 6 inches) tall. If that is correct, that person would have been healthy enough and lived long enough to grow very long bones in a prehistoric era. <https://en.wikipedia.org/wiki/Giant_of_Castelnau>[1](https://en.wikipedia.org/wiki/Giant_of_Castelnau) On a sixth hand, there was the extinct ape genus *Gigantopithecus* which may have walked on two legs or four legs. Some scientists believe that they were about 1.8-2 meters (5.9-6.6 feet) tall and weighed 180-300 kilograms (400-660 pounds). Other scientists believe they might have been much larger, standing up to 3 meters (9.8 feet) tall and weighed up to 540-600 kilograms (1,190-1,320 pounds). They are popularly imagined to be up to 12 feet tall. But *Gigantopithecus* almost certainly didn't have human body proportions anyway. I suggest that you study the lists of the tallest humans who ever lived and then find out about the health problems many of them faced. <https://en.wikipedia.org/wiki/List_of_tallest_people>[2](https://en.wikipedia.org/wiki/List_of_tallest_people) And possibly also study the lists of heaviest humans and find out about their health problems. <https://en.wikipedia.org/wiki/List_of_heaviest_people>[3](https://en.wikipedia.org/wiki/List_of_heaviest_people) It seems to me that if a group of humans become genetically adapted or scientifically modified to change their proportions to better fit their size, they could be healthy in gravity similar to Earth's gravity with average heights of about seven feet (2.13 meters), eight feet (2.43 meters), nine feet (2.74 meters), etc, and still look fairly similar to normal sized humans with only slightly different proportions. But it seems much less plausible to me that humans living in a one Earth gravity environment could be twelve feet (3.65 meters), or eighteen feet (5.48 meters), or twenty four feet (7.31 meters) tall, and still closely resemble normal sized humans. ]
[Question] [ In this world, the vehicles are effectively re-engineered insects; enlarged bio-manufactured nervous systems used instead of engines; factory grown lightweight chassis / [wheels]. The fuel station could be an algae pit or something similar. My question is basically, if you could redesign an insect's shape and size to be similar to that of a small 4x4, how much fuel would it require to get say 200 miles? what kind of oxygen intake it would it need to function? and, as a bonus question, what kind of technology (or biotech) could be used to command the vehicle? [Answer] > > if you could redesign an insect's shape and size to be similar to that of a small 4x4, > > > # No. Square cube law. When you double the critter's length, its volume is increased 8x, but its surface areas are increased only 4x. Which is why insects, with their tracheal respiratory system, can't grow past a few inches for the very largest ones. They would suffocate by growing larger. Last time they were longer than a foot our atmosphere had much more oxygen in it. If you do manage to grow an animal to be as big as a car, it won't be an insect. If you did start with an insect, the Zerg you'll be making will not be an insect anymore. [Answer] An insect, as it is commonly defined, cannot be scaled to the size you desire. They use [trachea](https://en.wikipedia.org/wiki/Trachea#Invertebrates) in their respiratory system, which cannot be scaled up to much greater size unless the oxygen content of the atmosphere goes up. And even then there will be [limits](https://en.wikipedia.org/wiki/Meganisoptera). So you are probably left with a reptile or mammal, even if genetic engineering gives it tough armor. For the fuel use of those, it will be *very* roughly comparable to the fuel an ox or an elephant needs to travel 200 miles. One could imagine that genetic engineering improves the efficiency of the digestive system, after all the other changes that were made. It will also depend on the energy content of the food. As a wild guess, several hundred pounds for 200 miles. [Answer] **Yes.** I am tired of square cube and the whole insects can't be scaled up thing. I want a 4 x 4 bug. By 4 x 4 I assume something like a Jeep. A jeep is roughly 2 x 2 x 3 meters I think. How to make a bug that big? I was going to start with a mighty coconut crab, but instead we will start with [Arthropleura](https://en.wikipedia.org/wiki/Arthropleura) the largest land dwelling invertebrate ever. [![arthropleural](https://i.stack.imgur.com/uvayg.png)](https://i.stack.imgur.com/uvayg.png) > > Arthropleura species ranged in length from 0.3 to 2.3 metres (0.98 to > 7.55 ft)[2] and a width up to 50 centimetres (1.6 ft).[3] Arthropleura was able to grow larger than modern arthropods, partly > because of the greater partial pressure of oxygen in Earth's > atmosphere at that time and because of the lack of large terrestrial > vertebrate predators. > > > As is this big bug has got the length. Now the other dimensions which we will achieve without violating the square cube law. We will put it on stilts, [Opiliones](https://en.wikipedia.org/wiki/Opiliones) style. These are the harvestmen, or daddy longlegs. They have got a lot of leg. [![daddy](https://i.stack.imgur.com/fmAvem.jpg)](https://i.stack.imgur.com/fmAvem.jpg) <https://www.livescience.com/24020-new-long-legged-arachnid-discovered.html> By the ruler I think that long leg is 15 cm and the body 0.5, so a leg to body ratio of 30:1. We will give our Arthropleural legs like that. The millipede body plan is better for this because the legs will presumably be supporting some weight, and so more is better. With 2 meter body that gives us legs of 60 meters. That seems a little extreme and so to keep things sane we will take the legs back down to just 10 meters. Of course they would be as thin as human fingers. You would have something like an extreme version of one of my favorite bugs, the house centipede. The 4x4 would have longer legs and more of them, being a millipede. Air intakes (spiracle equivalents) for the legs would help with oxidative metabolism out in the periphery. --- [![enter image description here](https://i.stack.imgur.com/EoYCe.jpg)](https://i.stack.imgur.com/EoYCe.jpg) Scoffer square cube fans might protest - the Arthropleura needs more oxygen than the atmosphere can provide! So your riders provide extra oxygen, which they carry in tanks. And the question: fuel. I used a calorie calculator <https://www.omnicalculator.com/sports/calories-burned>. and asked about a 10kg individual (the big bug); assume 200 miles at 10 mph = 20 hours running equivalent. It needed 1420 kcal which is about a Wendy's triple cheeseburger, fries, small Frosty and Diet Coke. Acknowledged - this calculator is for humans, which might be more metabolically wasteful than a millipede. Also this calculation is without a passenger. I think it might make more sense for the big bug to pull a chariot rather than have someone sit on its back; the legs provide lots of traction but people are heavy. [Answer] It has of course already been done in science fiction, in the excellent TV series Lexx. > > Lexx is a science fiction television series that follows the > adventures of a group of mismatched individuals aboard the **organic > spacecraft Lexx**. They travel through two universes and encounter > planets, including a parody of the Earth. > <https://en.wikipedia.org/wiki/Lexx> > > > [![enter image description here](https://i.stack.imgur.com/ZdzcM.png)](https://i.stack.imgur.com/ZdzcM.png) --- Lexx is the mother-ship. It can spawn Moths for use as landing craft. > > The Lexx spawns these Moth ships for use as landing craft, but they > are also indispensable for travel INSIDE the Lexx. ... ... ... > Mindless humanoid drones cultivate the Moths and ready them for > flight... Lexx can create dozens of Moths at a time when needed, and > as a last resort Lexx can actually eat the existing Moths when food is > not available. > <https://3dwarehouse.sketchup.com/model/ce40a04ccd7616e11dd0274343216065/Moth-Ship?hl=en> > > > [![enter image description here](https://i.stack.imgur.com/qx9uC.png)](https://i.stack.imgur.com/qx9uC.png) ]
[Question] [ So, one of my universes, is basically a 70’s retrofuture inhabited by anthropomorphic animals. They’re animals, for the purpose of creating a fragile civilization, as well as its themes of “Humanity returns to nature, when society breaks down.” What I’m asking is how plausible is it to have a world that functions on a system of pretty much, cannibalism? How could it work better? The standard societal structure, ever since the stone ages, was that the carnivores were the ruling class, the omnivores were the nobility and the herbivores were the peasants. Control over the peasants and society, was by periodical “harvests” where significant numbers of peasants would be culled to feed the ruling carnivore class. Otherwise, fish is the main sustenance for carnivores in between harvests. As society and technology advanced, their own “enlightenments” came about, where herbivores and omnivores gained more privileges and rights, as well as states that were run by omnivores and herbivores. Things were somewhat fine, while populations were small enough to support the needs of the carnivores without culling of populations. As everything continued to grow, and war destroyed resources, a worldwide famine was on the horizon, yet not many made an effort to halt it, for political entities all across the world, saw it as a perfect opportunity to strengthen their control over their own populations. Science is both encouraged and suppressed, as things like space colonization are seen as solutions to overcrowding and famine issues, but genetic miracles to end the famine, are held back like cards, waiting to play at the right moment. An additional question as well, is how long would it take for a world to “eat itself?” Say, all the meat eaters couldn’t get anything at all, so they riot, murdering for food, breaking apart societies into anarchy. How long would it take for people to starve, or kill a significant amount of the population? [Answer] As that odd person who has rocked up to a barbecue we've been at with their bottle of organic wine and wearing a 'meat is murder' T-shirt, *our* society still hasn't resolved the issues of eating non-sentient creatures to a perfect consensus. We have pockets of people who complain bitterly about GM foods for instance, but don't know that these foods have literally [averted famine](https://allianceforscience.cornell.edu/blog/2018/01/gmo-crops-could-help-stem-famine-and-future-global-conflicts/) in the past and are still our best hope for doing so into the future. The bottom line is that when there is plenty, you can be as selective as you like about what or who you eat. When there isn't, Maslow's Hierarchy of Needs kicks in. Changing a meat diet to fish for instance has already been done in the European past; many crusade knights ate a diet of fish as their exclusive protein on grounds that it was considered impious to eat meat. But in order to do so, there had to be a plentiful supply of fish to support those knights. Fishing industries picked up to support that need, and pasturing of sheep and cattle waned except for wool and dairy production. Of course, many of the peasantry still ate meat so it wasn't killed off completely, but the important thing is that there was a fundamental change in the balance of food production industries. For people who need to eat meat exclusively, and if fish isn't present, the best fictional analogue to your question is that of vampires. If we think of vampires as the carnivores in your model, and normal humans as the herbivores, it's almost an identical model and many of the issues you raise are covered in various fictional works. Want to swap out 'meat' for an alternative source? Look at True Blood. Want to look at Vampires as trying to live in harmony with humans and other races? Try Twilight, although I admit that it's a problematic example. Want to see the possibility of a hidden ruling class of vampires? You've always got the Underworld Franchise. The list goes on. In all cases, you'll find exceptions to the rule because not everyone wants the alternative in both food and culture that the protagonists represent. Someone wants true human blood, or open control of humans and/or vampires, etc. Your society will still have those kinds of power plays. Ultimately, humans see themselves as the only truly intelligent species on Earth and we abhor cannibalism because it's bad enough thinking of eating a creature at all, let alone eating a creature that can think. But, carnivores are unlikely to see their world in quite the same way, even if they become intelligent and even enlightened. The herbivores are still peasants; they're still food. I'd argue that the carnivores are highly unlikely to allow the herbivores to be come intelligent, let alone privileged in any society. Just like we've selectively bred dogs to be less intelligent (and more reliant on us) than wolves, like we don't breed sheep or cattle for their cognitive abilities, intelligent carnivores are more likely to 'farm' herbivores, not uplift them to a similar status to themselves. What you describe as cannibalism is really just cross-species predation, in a world where the prey is intelligent. Intelligent carnivores are actually going to breed that out of the herbivores because it's a complication to their food supply they don't need or want. So; as I see it, your society will function in one of two ways; 1) Your carnivores switch to fish exclusively and then embrace their former prey as a member of their society, making it both culturally and emotionally unpleasant to eat their fellow citizens, or 2) Your carnivores continue to eat the herbivores, but farm them rather than embrace them, breeding out the intelligence wherever possible to make their farming practices easier. If you go with option 2, your mixed species society is impossible. With option 1, there are some really interesting explorations to make around the moral and emotional decisions your carnivores may one day have to make if the fish run out. But, there may also be some members of your society who simply don't believe in a picotarian diet and end up becoming a form of serial killer in your society. There is of course also the issue of whether or not a former prey can ever *truly* be seen as equal to your carnivores. For inspiration on how option 1 may look in reality, there are plenty of vampirical and post-apocalyptic works of fiction that explore these kinds of moral dilemmas in a world where you just have to eat. [Answer] > > as well as states that were run by omnivores and herbivores. > > > Firstly being different species your issue isn't cannibalism which is only when members of a species eat other members of the same species, but set that aside. If the non carnivores are capable of this then they would exterminate the carnivores. They vastly outnumber them and would have a fifth column within each carnivore enclave, perhaps even outnumber the carnivores in their own homes. This has happened on Earth, cannibalism was used by elites in Polynesia and other places as a means of terrifying the populace. In each case eventually as numbers grew they were challenged and either changed their ways or perished. The last case in one country ended when the ruler pointed out a young girl for dinner, but what he received was his own eldest son gutted and cooked up for the feast. When people have nothing left to lose they will fight to the death like cornered rats except a LOT more dangerous due to intelligence and liability to do a bit of torturing and genocide when the tables turn. [Answer] **Caste System** Even if some herbivores are part of the ruling class, there will inevitably be lower class herbivore who will still be peasants, and at the very bottom 'useless' or 'undesirable' class who ensure the worst or illegal jobs. The carnivore can make their harvesting within theses lower class since the other social class will have little consideration for them, even may not considerate them as the same species. This system can be reinforced by a caste system, where everybody stay in the same social class all their life, because upper class herbivore will be certain to never be a part of the harvesting. At last, you can as well establish some sort of specism, where only certain species, seen as inferior, will be part of the harvesting. In conclusion, harvesting can be placed as long as it target only a precise category of people and the majority of herbivores are certain that them and their loved ones will never be harvested. ]
[Question] [ Saw *Pacific Rim* for the first time with a friend recently; I'd never really thought too hard about giant robots/been as into Mecha and Gundam stuff as some of my friends before, but the Jaeger concept got me kind of in the mindset for thinking up Fun Robot Designs, and now I'm trying to come up with some fun designs and quirks that make sense for something like fighting Giant Kaiju-Style Monsters, but which I haven't really seen in other designs I've looked up? An idea that I thought would be *super* neat is to basically have a Smaller and more compactly-built Jaeger-Type Mech, built to use its low center of gravity to its advantage and get up-and-under bigger foes to attack them where they're more vulnerable, use their opponent's own weight and momentum against them, and sacrifice increased size and outright lifting capacity for greater Durability (I noticed there were a lot of problems in the movie with Bigger Mechs not having much in the way of Crumple Zones, and being Long and Tall seems to come at the price of Balance and Stability- I like the idea of a Little Mech that's built in such a way that even if you *do* manage to crush it, the ways in which it Crumples/distributes stress shields the people on the inside and gives them time to either Recover and Fight On, or Bail Out if necessary). I also liked the idea of this bot having a sort of "Spring-Loaded" feel to it, something that can absorb a lot of physical shock and Bounce Right Back- Maybe even using the shock of your own attack to bounce back *at* you. XD That made me remember things like [prosthetic running "blades"](https://www.ossur.com/prosthetic-solutions/products/sport-solutions/cheetah) and [jumping stilts](https://www.air-trekkers.com/), and thought it would give the mech that spring-loaded feeling, improve its mobility when fighting large opponents across things like cityscapes and different terrain, and look *really* cool and unique if I could somehow incorporate something like these into the design of my Mech's legs! This isn't really something I've seen in very many Mech Designs, but that begs the question: Is that because someone who is Better At Robots than Me has already figured out that there are more disadvantages to this than advantages? I remember the argument about whether or not these sorts of prosthetic limbs gave *human* athletes too much of a competitive edge to allow them to compete alongside runners with Regular Human Legs, but is there any reason why this would be a serious design flaw for a *mech*, or impair the mech in some way? I'm sure there are disadvantages, everything has those, but do the disadvantages of a "blade-stilted" mech outweigh the potential advantages of one? I guess what I'm trying to get at is this: What advantages does a mech with "traditional" legs and feet have over one with Running Blades, and Vice-Versa? [Answer] I have asked a lot of questions about mechs in this site, every viability of them, and I even made spider mechs. I even created the "mechs" tag . All of them have one thing in common. **NONE** of them are viable First to note is the cost to create one. I doubt one would be cheap since engineers will have to think of ways of how to counter a barrage of solid sabbot from a tank so your mech can somehow withstand or dodge the attack, and that will cost a lot. Second is... the weakness a mech posses, specially humanoid versions. Destroy the leg. Third is range weaponry, tanks are the beasts in the battlefield because they could fire accurately AND pack LOAD of punch! Their center of gravity is so low that firing their cannons will hit the target almost 100% of the time (provided the target is not moving) and still withstand the following recoil the cannon gives. Do take note that's just countering a tank, we have yet to consider the munitions of every.single.weapon that we currently have(fighter planes, rockets, etc etc), how can a Mech withstand these threats? Are they realistic? How much might that be? Mechs wins in the rule-of-cool match against tanks but viability wise, its the opposite. I think your mech idea might be more viable as a powersuit, like Iron man. But I think that's for another question. **EDIT**: It may seem I have to give my shot on giving my answer to the "viability" of bladed Legs OR Cheetah legs, I'll be giving my answer for both, WITHOUT the knowledge or purpose of these legs. 1. **Bladed Legs** Or **Stilted Legs**: On humans they pretty much increase the height or your jump, the distance of each stride, granting you more mobility than a normal human AND can maybe used as a weapon (though this seems a bit dangerous as it compromises the integrity of your legs) This might be addressed by creating the legs similar to [this](https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcQLFZjlO9YI9k-pZOImt44GnefI8tDNC0UbaKDhwJ4BRa7IO6TbJA). These legs are just made from 3 main parts, the thigh, knee and leg (from knee to foot). The thigh and knee are connected by well oiled bearing enclosed and protected by the knee (sorry I can't give you a precise illustration about this mechanism). With these legs, this wont be used at urban areas for rescue and civilian duties because the legs will always drill down concrete. It is best used though, on urban warfare and rocky areas. Desert (specially sand only ones) forest and swamps are its worst workplace as these legs might be more of a hindrance than a advantage because they might drill very deep in these areas, restricting the granted mobility of these legs. My Personal Analysis: These legs might be more successful if equipped to human cyborgs or as a powersuit. The users can be equipped with sub machineguns and grenades. Give the user light armor than can protect it from most rifle rounds. the cyborg or powersuit is not invulnerable though, so it may fall down after several shots by high powered rifle, explosives and machine gun fire but its added mobility might help it bring down a couple of human infantry men, and a well placed kick might incapacitate a tank, before being destroyed. These legs however has several drawbacks: * Stealth: I can't seem to find a way to make these stilted legs to be stealthy, as they seem to drill holes on the ground each time the user steps, so the preferred usage of these units overall are ambush or full frontal assault. They might be best to be used as "take no prisoners" units, they are too, good in torturing humans for intel. * Turning: With the absence of feet, a quick turn is noticeable which *might* be a problem because veteran snipers might pick you with a single shot. I have not yet found any advantages of turning using your waist, so I'm going to assume that its better if the user will use the high mobility legs to dash forward, then jump turn to re engage enemies. * Costs: This might be debatable since a well placed jump kick dive can destroy a tank, then proceed to kill the infantry with its guns and explosives, however, the cost to built a cyborg to use these legs are neither cheap nor humane. Human transfer is the cheapest and best option because the brain can store at almost infinite information, and with the help of a computer, complex attacks *might* be possible. I do think that human flesh too will make the cyborg lighter, putting ceramic armor vests for protecting might increase the mobility of the cyborg because its armor is lightweight. So long as the cyborgs destroy an average of 2 tanks and maybe 24 infantry, I can say that this might be a viable approach NOTE: Do take note I created a cyborg because I think large mechs will have loads of problem using this. Examples are recoil and weapon choice. 1. **Cheetah legs**: IMO are the worst legs that you can put on a mechanized unit. Cheetah legs are slim to help cheetahs run at full speed. Slim legs for a mech however, reduces its grip for handling recoil. WE might create a mech, a lifesize cheetah mech that is capable of slashing its way around the battlefield with a retractable sword on its sides then maybe 2 rounds of armor piercing missles that can penetrate a tank's armor. BUT as long as we don't have a lightweight blade capable of cutting a human leg bone like butter then this legs are useless. Maybe for scouting purposes but, we already have aerial drones for that. TLDR: Creating a mechanized unit with these legs, especially the stilted one, *might* sneak to be a viable idea **IF** certain conditions are met. They are still faced with the common problems a regular infantry men faces(mines, IEDs,etc...) , or even a tank. But these doesn't change the fact that their greatest weakness is handling recoil. Giving stilted cyborgs small firearms and explosives is the most plausible thing to make them viable for war. They are restricted also for War use only, rendering them useless during peacetime. You can ride a tank on urban areas but you can't use the stilted legs, well maybe the cheetah can be a fast ride, so is a F1 race car. [Answer] Stability is going to be a huge issue. If you take a foot and ankle, it provides with you a large amount of control and a lot of different ways to apply force into the ground to keep yourself standing (think of standing on a rocky bus/train trip). With a spring type, you lose all this flexibility and you will need to compensate for it by moving your upper body and readjusting your stance. You will also need to synchronize your movements with the spring which limits the range of movements you can perform and the ease and conditions you can perform them under. For example, Muddy or soft ground will slow you down as you sink in. If you foot is stuck if will stretch and pull you back before you can free yourself, when jumping you need to time it with the down and up motion of the spring to maximize your jump, when kicking something the spring will compress reducing the effect. You might also have problems standing still, especially on sloped ground and the effects of debris and obstacles are going you to readjust your stance since you have no ankles and your point of contact with the ground isn't flexible like feet are. Also I'm not sure if we could actually make a spring that could support a mech as large as the ones in pacific rim. Springs deform and return to their original shape, but once a spring is large enough, its going to deform at different rates depending if the material is on the outside or inside of the spring and this could permanently damage it. [Answer] This is a very clear case of engineering that does not work at scale. As you scale up metal springs, they become less like springs and more like memory foam. By the time you get to Kaiju scale, they would not offer any meaningful advantages unless designed from materials that do not yet exist. Such a design would likely require a more pneumatic hammer like system to even approach feasibility. That said, your idea of a stout top armored mech made me picture a Puma from Mechwarrior. [![enter image description here](https://i.stack.imgur.com/UiVXx.jpg)](https://i.stack.imgur.com/UiVXx.jpg) [Answer] **Springs** As @nosijimiki has answered, springs don’t scale well, due to physics. Also remember that as the height of something doubles, the volume (and so mass) cubes. This means the burden on springs goes up incredibly fast. Furthermore, the density of a mech would be far higher than a human body. Whilst a simple leaf spring works fine for a human runner, a monster truck needs big oil/coil springs to give it (proportionally far less) bounce. I can’t think of anything larger than that which has ‘bouncy’ springs; it tends to be shock-absorbing. **crumple zones** You also asked about crumple zones. Crumple zones are used to protect from the sudden deceleration caused by a (blunt) impact against a wall, another vehicle, etc. They sacrifice the vehicle to protect the occupant against lethal or life-changing injuries. However, most weapons (bullets, shrapnel, etc) are penetrative rather than blunt impact. Crumple zones will not help protect against these. Rather you need rigid armour to prevent penetration - you may want some impact dissipation below this, but generally the rigid armour will spread the impact thus dissipating it. Ablative armours also work here. Weapons also function by shockwaves from explosions; The standard method to protect against this is a layer of (rigid) armour, then padding, then another layer of armour. But again, crumple zones offer no protection. So you don’t see crumple zones on tanks, because they’re useless. You probably do get them on military jeeps, but that’s to protect the occupants in an RTA, not against the effects of war. The only thing a crumple zone would protect a mech against is a blunt impact like a punch/kick from another mech. Realistically, fighting mechs like this is not viable. But suspending disbelief for a minute, remember that crumple zones sacrifice the vehicle - so if you’re relying on crumple zones, you’re accepting that you’re sacrificing the mech when the first punch lands. That’s probably bad economics for a war, and certainly won’t produce cool fight scenes. [Answer] To address the problem with a "blade-stilted" mech you run into issues with surface pressure very quickly. [![pressure equation](https://i.stack.imgur.com/ljtbt.png)](https://i.stack.imgur.com/ljtbt.png) You can see from this equation that pressure is force divided by the area it is exerted over. We can extend the equation for force as such: [![force equation](https://i.stack.imgur.com/vseaQ.png)](https://i.stack.imgur.com/vseaQ.png) With the sheer mass of a mech when you decrease the surface area supporting them you increase the pressure they exert per square foot and the earth can only support so much pressure before your mech just starts to sink in and lose efficiency and mobility. Decreasing the surface area of its legs to blade points would likely have the effect of its blade sinking most of the way into the ground making it impossible to be agile, any attempt at sudden movement causes a dramatic increase in pressure which would first cause your mech to sink further until frictional forces against the sides of the legs can support the added pressure. Whether your mech would have the range of motion or power to then withdraw its sunken legs from the ground is then questionable. ]
[Question] [ Humans all belong to a Single Species, localized on a single small-ish planet... Yet we are incredibly diverse in both Culture and Individual Appearance/Adaptation to our environment. This also seems to be true in relation to a lot of other species on Earth, even *without* breaking things down into Subspecies or whatever else. This is probably because the Climate and the distribution of land and water vary drastically from area to area, creating different biomes with life that has adapted in different ways in each. However, in a lot of Sci-Fi, aliens we meet show relatively little divergence from Others of their Species, either culturally or physically? While this can probably be explained by the limitations of whatever narrative medium/framing device you're looking at, or might have some in-universe explanation (there IS a difference but humans find it hard to tell because we aren't familiar with their biology, or a specific COUNTRY on their planet might have sent this bunch, etc.), that did get me thinking... We obviously know very little about what life is like elsewhere in the universe, but based on what we *do* know, is there any evidence that Earth's extreme diversity might be somehow Anomalous? Or would every planet capable of producing what we might call "People" need to be equally complex in order for them to develop, and as a result would they be just as Diverse as we are? Is there any real evidence that points one way or the other? I personally tend to *feel* like it must be the latter, but I'm not really an expert on much of anything, so I thought it would be a good idea to see if anyone else had read any "official"/scholarly material posing or exploring the question, or even had any thoughts of their own with evidence to show where they're coming from? I'm writing a thing with multiple alien species reaching out to each other, and I feel like this line of thought/study could give me some insight into how to handle each population's own Internal Reactions to this. :) [Answer] # Appearance will homogenize over time Humans are currently pretty diverse —but we're also (realistically) centuries from being a multi-planet civilization capable of terraforming and expanding across the world. Given how much we have already begun to intermix over the past century and how much more acceptable miscegenation has become, I think it's safe to say that if humanity ever becomes spacefaring, we will be a smoother gradient once we get there. # Homogeny is an illusion born of unfamiliarity Even among humans, people of one race often have trouble telling apart some members of other races, *especially* if they lack familiarity with the individuals, or have not been exposed to many of them. Tropes of "all x people look the same" are present in many cultures. And this is between the members of a single *species*. Take a look at a few pictures of, say, tigers, or zebras, and tell me you could tell two of them apart at a glance. # Homogeny is dependent on sensory perception I think all humpback whales look the same, to be honest, but they each have their own *song* as an identifier, one that I, as a human who uses eyes to decide who is who, would be rather put upon to figure out and remember which is which. Ants tell each other apart by smell, and lemme tell you, they all smell the same to me. I might think that ants and humpback whales are homogenous, but that's because I don't perceive the things that tell them apart to each other. There's no reason the same wouldn't be true for aliens. [Answer] Well, Vulcanoids are every bit as diverse as Humans: [![Asian Vulcan](https://i.stack.imgur.com/4hOgA.png)](https://i.stack.imgur.com/4hOgA.png) Asian Vulcan [![More Asian Vulcans!](https://i.stack.imgur.com/2wbnB.jpg)](https://i.stack.imgur.com/2wbnB.jpg) More Asian Vulcans! [![African American Vulcan!](https://i.stack.imgur.com/BOHz0.jpg)](https://i.stack.imgur.com/BOHz0.jpg) African American Vulcan [![Caucasian Vulcan](https://i.stack.imgur.com/oijxV.jpg)](https://i.stack.imgur.com/oijxV.jpg) Caucasian Vulcan [![Black Vulcan](https://i.stack.imgur.com/48lmV.jpg)](https://i.stack.imgur.com/48lmV.jpg) Black (Mestiza) Vulcan [![Ukranian Jewish Vulcan](https://i.stack.imgur.com/EmE3x.jpg)](https://i.stack.imgur.com/EmE3x.jpg) Ukranian Jewish Vulcan [![African American Romulan](https://i.stack.imgur.com/mnYac.jpg)](https://i.stack.imgur.com/mnYac.jpg) African American Romulan [![Vulcan Evil Twin Romul and and Caucasian Romulan](https://i.stack.imgur.com/yNnxa.jpg)](https://i.stack.imgur.com/yNnxa.jpg) Vulcan Evil Twin Romulan and Caucasian Romulan In the literature, I'd say heterogeneity is the rule rather than the exception. [Answer] You added the tag [reality-check](/questions/tagged/reality-check "show questions tagged 'reality-check'"). Completely impossible, of course. All we can do is guesstimate. # A Matter of Viewpoints: Take humans. Most you see have two legs, two arms, a head on top with two eyes, teeth in the mouth covered by lips, and so on. And the vast majority of those who make it into space during the next years will speak English, at least well enough to communicate with air traffic control. There is a big difference, some of them have mammaries and some do not. But that is not what you mean, right? Other than that, little differences in skin, eye, and hair color don't really matter. *Someone who is part of the species will take similarities for granted and notice differences. We're biologically programmed to tell other people apart.* That still leaves political differences. There are plenty of precedents in science fiction where there are political or cultural factions within alien species. Even more where the break is on species lines, of course. * C. J. Cherryh, [Alliance/Union](https://tvtropes.org/pmwiki/pmwiki.php/Literature/AllianceUnion) universe The story arc in the alien Compact is about factions of some alien race finding common ground, for interstellar stability and against their short-sighted homeworld leaders. * Larry Niven, [Known Space](https://tvtropes.org/pmwiki/pmwiki.php/Literature/KnownSpace) universe The adventure in [Ringworld](https://tvtropes.org/pmwiki/pmwiki.php/Literature/Ringworld) is triggered by factional differences within an alien government. * Iain Banks, [Culture](https://tvtropes.org/pmwiki/pmwiki.php/Literature/TheCulture) universe Much of the adventure in [Excession](https://tvtropes.org/pmwiki/pmwiki.php/Literature/Excession) is caused by power plays between AIs. [Answer] You use the terms "incredibly diverse" and "extreme diversity" when talking about human physical and cultural traits, but I'm not sure those are accurate descriptions on the scale of the universe and really only apply at the most superficial levels. It's easy to forget that humans are organisms of cells that are in fact extremely homogeneous. There are only about 10 or so different types of cells in the human body and two healthy humans of the same mass and sex have them in roughly the same proportions. Then of course all of the cells have DNA and any two individual humans have roughly 99.4% of the genome in common. All of this commonality is essentially why human pharmacology works. I would also argue that we share at least 99% of our cultural traits. Humans generally like, dislike, fear, admire, are disgusted by, and are attracted to the same things, individually and as part of societies. The differences are by and large superficial and the result of localized histories. To quote Tip O'Neill: "All politics is local". So would an alien race be as diverse as us? I would say the odds are high that the answer is 'yes' simply because fundamentally we are not very diverse at all. To quote Isaac Newton: "Nature is pleased with simplicity, and affects not the pomp of superfluous causes". ]
[Question] [ The moon in question is composed entirely of a radioactive substance, and showers the earth with strong radiation. It is responsible for a particular kind of cancer that causes the cells to multiply out of control fairly quickly. Over time, the victim will mutate into a shambling monstrosity that is a danger to everything around it and will eventually die. The moon is responsible for a number of other anomalies, such as stillbirths and miscarriages. Even more rarely, pieces of moon rock break off and fall to earth, emitting radiation in the surrounding area and putting people at risk. Despite this, most of the population are unaffected by the moon, and the majority will not contract this disease. Most areas on the planet are also unaffected by the radiation from the moon. The ozone layer doesn't seem to be a viable reason, since it doesn't explain why a relatively few contract and others do not. Why would this be the case? What prevents the moon from mutating and killing the entire planet as well as the population? [Answer] The average dose people get from the Moon and environment lies well within the safe thresholds for radioactivity exposure. [According to XKCD](https://xkcd.com/radiation/), the normal early background dose radiation a person recieves [lies around four millisierverts:](https://en.wikipedia.org/wiki/Sievert) (click to expand) [![Gotta love XKCD](https://i.stack.imgur.com/mwElO.png)](https://i.stack.imgur.com/mwElO.png) Quoting Munroe himself: *I waive all copyright to this chart and place it in the public domain, so you are free to reuse it anywhere with no permission necessary.* I am placing this chart here so that you can check what kinds of things are radioactive and how much radiation they give out, so that you can tune the radiation levels of your Moon during special events if you wish to give your audience an idea of the radiation levels involved. So everyone might be getting just a few microsieverts from your Moon during a year, but on special occasions it will emit more radiation than usual. Some ideas: * During [supermoons](https://en.wikipedia.org/wiki/Supermoon), [blue moons](https://en.wikipedia.org/wiki/Blue_moon), or [blood moons](https://en.wikipedia.org/wiki/Lunar_eclipse). All of these happen a few times per year. If you wish to make it more rare, consider a combination of those events - for example, we've had one super blue blood moon in 1866, and then another in 2015. Supermoons will give more radiation because the Moon is full and at its closest to Earth. Blue Moons are the second full moon of a month - these are only a thing because of our calendars, but in your world, you could make it so that full moons don't happen at regular intervals. Therefore, two full moons close to each other would give out more radiation than normal. Finally, Blood Moons are lunar eclipses in which the Moon appears red. Maybe solar wind actually sweeps radioactive particles from the Moon away, so its darker side is more radioactive. New moons will be more radioactive than normal, but Earth will be protected by some solar wind still. But during a lunar eclipse, there is much less solar wind between the Moon and the Earth than during a new moon. * During a solar eclipse, alignment of the sun and moon might cause the solar wind to combine with the Moon's own radiation to become more dangerous. Perhaps the particles in the solar wind would trigger some transformation on the Moon (which could be the cause for its radioactivity in the first place), and the fact that the solar wind will now carry Moon particles as well helps them pierce the Earth's atmosphere in larger quantity. * The Moon in your universe is not tidally locked to Earth. It does not always expose the same face and it has an axial tilt of its own. One region near one of its poles is more radioactive than the rest of its surfaces - so when the Moon season is right, it will shine more radiation onto part of Earth's surface for a few nights. [Answer] The simpler explanation would be that the population has evolved a **very** efficient antimutagenic mechanism, possibly based on something like a specialized human [helicase enzyme](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4538698/). *But* the mechanism isn't perfect: perhaps the enzyme requires some element that is present in *most* areas of the planet, but not all, to work (e.g. like [molybdenum on Earth for nitrogenases](https://en.wikipedia.org/wiki/FeMoco)); perhaps stresses, or some viruses, or lack of a different micronutrient make the mechanism go awry. The end result is the same: most people, most areas of the planet are unaffected by the gamma radiation, but some others are not - and the results are quite messy. [Answer] A more interesting turn of this question might be "what are the health benefits associated with a radioactive moon?" In Taiwan, there are a number of buildings from the 80s that were accidentally built out of scrap metal containing radioactive substances. At least one long term study of this phenomenon has yielded a curious result - people are living *longer.* If true, and attributable to the radiation, it requires a kind of 'goldilocks zone' that amounts to extremely low level radiation therapy - mutated and damaged cells, like precancerous tissue, are being cleared out before they become a problem, resulting in statistically significant changes to mortality rates. But it's not like these people never get cancer. They just get it less, and later in life. And this suggests a framework for an answer. On the whole, statistically, and for most people, the radiation isn't necessarily doing harm. Damaged, mutated and precancerous cells are, *statistically*, being cleared out faster than the immune system can do the job by itself. The problem arises when *that one* cell doesn't finish dying, it's broken in *a very specific way*, and it's in a place an immune system can't really go. This is basically how cancer works in people anyway - the only thing left for you to handle in this situation is "why monsters?" [Answer] Your moon is not made completely of the radioactive substance. It has a radioactive meteor embedded at one location in the surface. When that meteor points at the world below, the world is hit with radiation. The meteor comes around once each spin of the moon. The moon spins very slowly. It might complete several rotations around the earth before it brings its hot side to bear. You could make it even less frequent by having the moon in an elliptical orbit. The radioactive meteor might be pointing inwards but the moon is at the far point of its ellipse, and so does not radiate its planet. So: the radiating of the planet would be an infrequent and much dreaded occurrence. I propose that entities planetside could see the meteor when it faced them, because it was a different color or perhaps glowed. [Answer] The moon will have a very complex structure and only the moon surface has to be radioactive. Else, the moon will be a second sun - will radiate a lot of heat and some light. If the real-world Moon was radioactive, we would not notice until the space era - the atmosphere filters out everything. I would suggest a rather strong meteorite shower: on earth, they just make a fancy fireworks and no major ill effects. On the moon, they occasionaly eject surface material and it falls on earth. (There are a real-world examples of moon meteorites.) Add to the picture that on earth, the radioactive substance is rather quickly dissipated by weathering out (there are some useful isotopes, K-40 comes to mind). ]
[Question] [ I am designing a world where one world power or set of world powers have developed commercial fusion reactors. The fusion of this world meets all of the expectations fusion we believe might be possible -- a person's lifetime energy needs are met with a cup full of sea water, a hydrogen economy is developed, phosphorous fertilizers become cheaper, etc. All of these outcomes offer tremendous benefits. However, the country or countries that develop commercial fusion refuses to share the technology (or critical components not . Or, more likely, smaller countries are unable to afford this massive innovation. For the purposes of this question we will assume that a large tokamak style reactor is needed, a tremendous expense in at self, that additionally require powerful magnets to achieve plasma containment / compression. To build on the above, the issues associated with magnetic confinement require a rare superconductor and only the originating country that can create it. Why would a country such as the US or China share this blockbuster technology? What would the outcomes of not sharing this technology? In the interest of making this question more objective (and less opinion based) please cite historical precedence for innovation, preferably in energy production, or science based fiction where possible. [Answer] The country that develops limitless (almost) free energy is at a massive economic advantage over every other country. They wouldn't release it. They would protect it from spies and possibly even go to war against any country that stole the technology from them. If America (for example) developed it, it could build said reactors as part of their military bases around the world and on sell the excess energy to the host country. This would give America additional military power and create a dependence in the host country to the point where countries would virtually become vassals of an American empire. Countries that didn't want American military bases would have to produce their own power at a much higher cost which then affects the production costs of trade exports. Energy is like a drug to countries. They will sell their soul to get it cheap.... [Answer] ### Based on your assumptions, the fusion reactor was probably a gray project, contracted through companies that were legally bound to keep the research and development highly classified, similar to classified military tech like the B2 Stealth Bomber: From Wikipedia: > > During its design and development, the Northrop B-2 program was a gray project before its revelation to the public. Unlike the Lockheed F-117 program, which was a black project, the type of military project of which very few people knew even existed while it was being designed and developed, more people within the United States federal government knew about the B-2 and more information about the project was available. Both during development and in service, there has been considerable importance placed to the security of the B-2 and its technologies. Staff working on the B-2 in most, if not all, capacities have to achieve a level of special-access clearance, and undergo extensive background checks carried out by a special branch of the Air Force. > > > For the manufacturing, a former Ford automobile assembly plant in Pico Rivera, California, was acquired and heavily rebuilt; the plant's employees were sworn to complete secrecy regarding their work. To avoid the possibility of suspicion, components were typically purchased through front companies, military officials would visit out of uniform, and staff members were routinely subjected to polygraph examinations. The secrecy extended so far that access to nearly all information on the program by both Government Accountability Office (GAO) and virtually all members of Congress itself was severely limited until the mid-1980s. Northrop (now Northrop Grumman) was the B-2's prime contractor; major subcontractors included Boeing, Hughes Aircraft (now Raytheon), GE, and Vought Aircraft. > > > In 1984, a Northrop employee, Thomas Cavanaugh was arrested for attempting to sell classified information to the Soviet Union; the information was taken from Northrop's Pico Rivera, California factory. Cavanaugh was eventually sentenced to life in prison and released on parole in 2001. > > > The B-2 was first publicly displayed on 22 November 1988 at United States Air Force Plant 42 in Palmdale, California, where it was assembled. This viewing was heavily restricted, and guests were not allowed to see the rear of the B-2. However, Aviation Week editors found that there were no airspace restrictions above the presentation area and took photographs of the aircraft's then-secret rear section with suppressed engine exhausts from the air, to the USAF's disappointment. The B-2's (s/n 82-1066 / AV-1) first public flight was on 17 July 1989 from Palmdale to Edwards AFB. > > > In October 2005, Noshir Gowadia, a design engineer who worked on the B-2's propulsion system, was arrested for selling B-2 related classified information to foreign countries. Gowadia was convicted and sentenced to 32 years in prison for his actions. > > > The B-2 bomber is still classified technology, even though it is now deployed in service. People can see it flying around, but there are still many secrets to its design: > > The bomber does not always fly stealthily; when nearing air defenses pilots "stealth up" the B-2, a maneuver whose details are secret. > > > ### So we know that a government can, through the methods used on the B-2, create a technology that no one else knows much of anything about. Why they would do that for fusion is up to your story. ## I can't tell you why people in your story make choices, but if you are looking for inspiration, there are a couple possibilities: ### Dominance through simple energy superiority and independence: Countries succeed by leveraging resources. Sources of energy have become one of the most important resources. Fossil fuels are a big deal. Countries that have it or can get it prosper. Those who can't fall behind. If your country has fusion but others do not, you race ahead of them, making yourself a dominant power. You can make fusion-powered war machines and they can't. Your electricity is so cheap that manufacturers start moving operations to your country, boosting your economy. They wouldn't make that move if fusion will soon be coming to their current location. Your street lights and electric trains run for almost free. Your citizens can charge their electric cars for almost free. Your GDP would explode. If you share this tech, then the world advances together. If you withhold it, then you pull far ahead of the others. ### Keep control of the reactors, but sell the electricity for money and political or strategic deals. The superpower that has the fusion tech under government control could make deals to sell the power output, but not the tech itself, to other countries. If another country wants to be able to buy the cheap power, they have to give the superpower some land (of the superpower's choosing). The superpower will build a reactor and also a military base on that land. The reactor will be on super-power sovereign territory, and protected by the base, but the small nation's power grid can connect some power lines to the output. This is a sweet deal for the superpower. They get to build new military outposts and also sell electricity. Since the small nation is now dependent on the electricity, they are close to being a vassal-state of the superpower, who can threaten to cut the power if they misbehave. [Answer] **Monopoly.** A parallel is silk. The knowledge of how to produce silk was kept secret for hundreds of years, allowing the Chinese to monopolize this very desirable product. I did not realize that the Byzantines had a similar monopoly much later after silkworm eggs were smuggled out of China. <https://en.wikipedia.org/wiki/Sericulture> > > In the 6th century the smuggling of silkworm eggs into the Byzantine > Empire led to its establishment in the Mediterranean, remaining a > monopoly in the Byzantine Empire for centuries (Byzantine silk). In > 1147, during the Second Crusade, Roger II of Sicily (1095–1154) > attacked Corinth and Thebes, two important centres of Byzantine silk > production, capturing the weavers and their equipment and establishing > his own silkworks in Palermo and Calabria,[7] eventually spreading the > industry to Western Europe. > > > So too fusion. Fusion can be used to make a number of salable products, for energy or otherwise. Unlimited energy would allow, for example, the production of alkane fuels out of CO2 even more cheaply than drilling for oil. It would allow the synthesis of precious metals from base elements. Just about any raw material could be made. If everyone can make these things, they are worth little and then the price crashes. By restricting the availability of the energy technology, the owners of fusion maintain scarcity of products sufficient to maintain demand and allow profitability. [Answer] There's a few options that come to mind **Fear** When Nuclear power became possible, the technology was not immediately shared either, for a simple reason, if a country can build a reactor they can also build a bomb. ANYTHING that can produce a large amount of power must have an ability to get that energy from its fuel in some way; weapons simply require that same process to be done but in an instant instead of over time. so Fusion reactors could lead to a way to use the same process however they've (insert required plot point... more heat, less control mechs etc...). this could lead to a weapon that could fracture a tectonic plate and potentially end the planet... if that was the case it wouldn't be hard to see why they'd keep a lid on it. And yes i know i'm over simplifying the difference between a reactor and bomb **Economics** Another possible is that the US economy is basically based off the value of Oil, if another country found a way to miniturise the technology to power cars etc it would cripple the current US. this would be dependent on how the US economy would be effected by the Fusion process in the first place... **More Economics** Maybe the one material Product X that without it the fusion reactors wouldn't work, and that only the fusion owning country could produce was actually a refinement of Product Y, something that only another country produces and by giving out that tech the other country would realize that they hold the key to the power and ramp the prices up. **Bad Press** Or you could go completely down the rabbit hole and have it be powered by Soylent Green... and they don't want the bad press ]
[Question] [ I am including some dragons in the universe I'm building. Now, I have already decided that only baby dragons will fly, but I am having some problems with breathing fire. My current design: Dragons have lots of symbiotic anaerobic fungi in their alimentary canals. Breathing fire requires a diet heavy in sugar, and as a result, dragons will often make their homes in places with lots of carb-rich food. The symbiotic fungi will break down the sugar, producing alcohol which will be stored in special glands on either side of the end of the dragon's mouth. The dragon's tongue has a small, hard protrusion under its tip. When the dragon must breathe fire, its alcohol glands undergo violent convulsions, ejecting their load with great force. At the same time, the dragon strikes its tongue against one of its teeth, creating a spark that ignites the alcohol. For extended torrents, glands in its mouth secrete an oily, highly flammable solution. The dragon sets this on fire, and then proceeds to shoot a continuous barrage of alcohol. Fire-resistant mucus protects its mouth. Now, I'm pretty sure there is a problem with the science somewhere. Can somebody help me find it, and/or suggest a better method? [Answer] The method seems a bit convoluted, not to mention that a dragon who eats a carb rich diet will not be capturing princesses, but attacking fruit orchards to get the materials needed for fermentation. (This also leads to the interesting question of why vegetarian dragons need to breath fire on the first place.....) What may work better is to scale up the defence method of the Bombardier beetle: [![enter image description here](https://i.stack.imgur.com/4OrTw.jpg)](https://i.stack.imgur.com/4OrTw.jpg) *Bombardier Beetle in action* The beetle essentially secretes two chemicals in glands in the abdomen, and squirts them out the back end. The chemicals are hypergolic (react in contact with each other), releasing a searing chemical spray against their enemies. For anatomical reasons this is going out the back, there are strong sphincter muscles to contain the chemicals and all the abdominal muscles can contract to mix and eject the chemical spray. Dragons could do the same trick with glands full of [hypergolic](https://infogalactic.com/info/Hypergolic_propellant) chemicals in the cheeks or throat, and coughing (or even vomiting if things are far enough back) to eject the chemicals, hopefully the mixing of the spray occurs far enough forward that the ignition point is past the dragon's face (breathing in fire is especially not recommended). Or the dragon could be like the Bombardier beetle and shoot fire out the cloaca. The warning sign for brave Sir Knight is when the dragon suddenly turns around...... [![enter image description here](https://i.stack.imgur.com/K9kOv.png)](https://i.stack.imgur.com/K9kOv.png) *Hypergolic reaction. Imagine a pressurized mixture* [Answer] For sustained fire breathing, you **need** an insulator (A thick mucus or secretion) If you atomize it using air (violent convulsions will lead to spurts) than you can extend the duration of fire at the cost of heat; this is what we do in combustion engines. Also atomized ethanol with salt (to prevent the colorless flame) it will look brighter, be hotter, and last a good while (4 hr per liter) longer <https://www.hemmings.com/magazine/hcc/2012/08/Fuel-Atomization/3715001.html> <http://www.greenethanolfireplaces.com/how-long-does-bioethanol-fireplaces-burn> <https://www.youtube.com/watch?v=x_eK9K6UQoY> [Answer] Ok, to me the easiest way would be to create a dragon that is either ruminant OR that have his diet strictly made of ruminants because his digestive system is made for that. You know, the sheeps, and the deers and the cows. Now, as ruminant (or ruminant eater specialist) he have few stomachs and one of them is made for that grass and methane. Or to be exact the absorption of methane. It then can be stored in bags near the spine that are pressed when dragon take a deep breath. So he have oxygen in lungs which he can exhaust with the gas and crate flammable mixture. Kind like humans have one opening for air and food but still can have food in mouth and air in sinuses. Or how you laugh so much you spit milk out of your nose. Now the problem is how to create a spark to light that. Again, easiest option would be teeth with traces of flint. Somehow, like we human produce stones in kidneys and have tartar, dragons can have flint. It can be created within dragon itself. Back to digestive system. As silicon is present in many plants (see typical dragon diet) and thermal waters it could be paired with oxygen. Thermal waters would also mark natural occurrence of dragons or dragons lairs. It would also create a natural diversity among dragons as those who eat moose don't have such sustained fire breaths (more meat less grass so fever meals) or dragons that can't breath fire (as not everybody have kidney stones) but still make people die in their vicinity (as methane is odourless but people suffocate with the lack of oxygen). With your design I would go with fully vegetarian dragons. Why? have you tried ever to squirt an orange skin into the lighter? Yeah, the juice in citruses skin is alcohol and flammable (also it smells nice). So your world could have a lot of different citruses, dragons eat them, and again digestive system, are able to store Limonene and later use it. And that also could serve as world building as in warm climate there would be a lot of dragons but very calm as there is a lot of food. While in colder climates the food would be scare the dragons would be angry and more prone to attack settlement and drink human stored mead. [Answer] I know that this question's a bit old, but I happened to know something on the matter, so I thought I'd add my grain of salt. So, there are two ways I know of of doing this: 1. The evolutionarily plausible one, but perhaps a bit of a copout 2. Actual fire possible, but evolutionary background questionable So, let's look at number 1 first. This, while not actually fire, could achieve the effect of fire, while retaining the plausibility of them looking so much like real squamates. So, a poison gland in the jaw produces a very strong zytotoxin that burns skin, causes paralysis and induces fever. Upon contact, the skin of animal would blister, and the venom would flow through the victim's veins, feeling very much like fire. This could potentially liquefy the inside of smaller prey, and do so partially for larger quarries. But, there are a couple of problems with this so far. The first one being that dragons are very big, and the range might be unsatisfactory for a "cool" plot. So, I suggest adding muscles around the poison glands which contract and pump the glands, shooting the poison several metres. These muscles would also allow the dragon to regulate the amount of venom they squirt. The second problem is that reptiles shed their teeth very often - and the teeth are the best body part I can think of for the poison to go out of. But, there is a solution at hand. If the venom glands only connected to a few permanent fangs, the rest could be shed as usual. But, you asked for fire, and that's not really fire. So, if you're not really that pushed on explaining the evolutionary background of dragons (Convergent evolution could potentially do it, anyway.), there's another method that could achieve real fire-breathing. Suppose you had a group of animals that had formed a symbiosis with microbes in their digestive system that produced hydrogen as a metabolic waste product. Some of these animals could store and compress the hydrogen in organs rather similar to lungs, and expel it through a tube leading to their mouths. The hydrogen would be ignited through bioelectricity, giving them the ability to spew flame. But, there are obvious dangers when it comes to breathing fire. Perhaps your dragons could have a "false pallate" like crocodilians, which would prevent fire backfiring and barbecuing the dragon's insides. To protect their eyes, they could have a transparent membrane like seals and other animals. There are some possibilities of fire-breathing aside the classic "Ima burn you" purpose. For example, dragons with less powerful flames could use it to start bushfires instead - igniting dry vegetation to create an inferno. To take a leaf out of the whales' book, each species could have unique flame shapes that would distinguish them from different animals. [Answer] There are several problems with this means of generating flammable compounds: 1. Alcohol-producing organisms are poisoned by the alcohol they produce before the concentration of alcohol increases sufficiently for it to be flammable. Flammable alcoholic beverages are *distilled*. 2. The dragon must consume a sufficient quantity of whatever food is required to be fermented. 3. Alcohol burns at a relatively low temperature, so as a means of producing a flame, it is not too effective. You'd be better off having your dragon have a conventional dragonish meat diet, and have it produce flammable oils that it can ignite - such oils have a higher energy content, burn hotter, and may be produced by biochemical processes within the dragon's own tissues. A better solution still would be for the dragon to obtain its fuel from an external source, but flammable or better yet, pyrophoric compounds, or even their precursors, are difficult to obtain in the natural environment. [Answer] I think hypergolic fuel is the way to go. They can be mixed and stored separately, and combined in or slightly ahead of the mouth. ]
[Question] [ I haven't been here in a while but I got another question, Would it be scientifically possible for sunlight to cause a zombie to self combust into flames? And if they would only self combust if their heads were exposed to it, but if they had head cover or gear, then they would be perfectly ok? I know this sounds quite a bit like a concept from Minecraft (because it's based from that), but I would want to know if it's scientifically possible. [Answer] **The Short Answer** *No*. In the realm of scientific realism, there are no chemicals that are simultaneously so sensitive to light that it would trigger an exothermic reaction strong enough to burn a "person" to "death", while stable enough that they could otherwise be carried about by that person. **The Longer Answer** On the other hand, you already have zombies. Assuming they're actual "dead former people now walking and doing things", your scientific credibility is already in sharp decline. So if it's something you really want as a characteristic of your zombies, you could make it happen. Let's say that your Z-parasite, your microorganism/parasite/magic that makes the zombies, was originally created to organically generate [binary fuel](https://en.wikipedia.org/wiki/Hypergolic_propellant) for something. It keeps that fuel in the space formerly reserved for its victim's brain, separated by a (for an equally contrived reason) extremely photosensitive but otherwise impermeable membrane. Expose the holes in that "zombie's" head to light, the membrane degrades, a bit of the fuel components touch one another, and **whoosh**. [Answer] **Real Life Case of a Toxic Woman** She didn't exactly *explode,* but a woman brought into an emergency room suffering organ failure died and then gave off a noxious gas that injured several hospital workers. She had been taking cancer meds and possibly huffing solvents, one of which may have reacted to the oxygen and a few of the medications the doctors gave her to become a highly toxic gas. The cause is not definitively determined, but the fact that a dying woman's body seemingly manufactured and spewed some sort of nerve gas is an actual medical mystery that some very determined investigators are still trying to solve. <https://skeptoid.com/episodes/4291> Perhaps instead of exploding you could have some kind of fictional drug that was used to try and treat the victims of the zombie virus that now makes them toxic to be around, or release some kind of gas that is highly combustible. [Answer] We can **assume** the zombification is used by a fungus that infects the dead flesh and forms networks that enable it to simulate animal behauviour, process sensory stimulus, and operate the musculature of the host body. Zombi attacks are then simply attempts to spread the spores via saliva and to weaken the immune system of the victim until it can't fight off the fungal infection. At which point the infection kills the victim and produces a dead body it can control and use to spread itself. Ability to see would require the fungus to infect the retina. It is the one place in the body that has the optics to produce an image. The fungus can't use the nerve cells of the host since those are not operating properly, it must do the sensing directly. We can further **assume** the fungus is not only light sensitive it actually takes damage from the UV in sunlight. This means that unless the eyes are protected from sunlight by some sort of head gear, the fungi infecting the eyes will die or be suppressed. This will blind the zombi which is sufficient reason to avoid sunlight by itself but we want it to trigger self-ignition. Easiest cause would be bacteria that consumes the flesh of the zombi but is normally suppressed by the fungus to some sort of mostly harmless equilibrium. When sunlight suppresses the fungus the bacteria goes berserk and produces enough heat to make the volatile compounds in the flesh combust. Zombi flesh has no blood circulation so its temperature can rise locally easier and faster than in a living human. Especially since those same volatile compounds make a convenient energy source for the bacteria. Now we just need to handwave in a reason for the flesh to be rich in volatile compounds. And I mean handwave, the actual metabolism and chemistry of zombies is bit beyond current science for obvious reasons. But it is reasonable to **assume** that zombie flesh is fairly energy rich and possibly flammable. Zombies do not have a blood circulation. This means not only that they dry out making them directly more flammable but also the flesh can't use blood to redistribute energy from storage to muscle. The energy needed for metabolism is stored locally in energy rich compounds. These would make good food for bacteria and reasonably break into volatile and flammable compounds when heated. (**Ass-u-me**, the thing that makes an ass out of you and me. <- sufficient disclaimer?) [Answer] This can be achieved if your zombies have a lot of sperm in them. ![enter image description here](https://i.stack.imgur.com/XwgWC.jpg) Still reading? Sperm oil is probably not what you are thinking, unless you are knowledgeable about whales. It is extracted from sperm whales (and from the head, not from the testes). [From the wiki:](https://en.wikipedia.org/wiki/Sperm_oil) > > In the late 18th and early 19th centuries, sperm oil was prized as an illuminant for its bright, odorless flame. > > > flash point 260-266°C > > > 260ºC = aprox 500ºF So you need the zombies to some sperm oil in them. You could explain that as a byproduct of zombification. The next step is to get zombies to reach the flash point when exposed to sunlight. You could explain that with an extreme form of cutaneous porphyria. Porphyria is a disease linked to the legends of vampirism, [with symptoms such as:](https://en.m.wikipedia.org/wiki/Porphyria#Chronic_porphyrias) > > (...) severe shortening of digits, loss of skin appendages such as hair and nails, and severe scarring of the skin with progressive disappearance of ears, lips, and nose. Patients may also show deformed, discolored teeth or gum and eye abnormalities. > > > The mechanism through which it acts goes like this (from the same link as above): > > Skin disease is encountered where excess porphyrins accumulate in the skin. Porphyrins are photoactive molecules, and exposure to light results in promotion of electrons to higher energy levels. When these return to the resting energy level or ground state, energy is released. This accounts for the property of fluorescence typical of the porphyrins. This causes local skin damage. > > > So there you have it. Monsters filled with flammable oil, and with a photoreactive substance known to exist in porphyria-affected humans accumulating on their skin. Just add a little sunlight and watch the fireworks! [Answer] **Gases and Heat** * We know [decomposing bodies produce gasses](https://en.wikipedia.org/wiki/Chemical_process_of_decomposition) such as carbon dioxide, hydrogen sulphide (highly toxic), ammonia, methane and etc. * Depending on your world the virus responsible for zombies 'being' could have a byproduct producing an even more unstable decomposing gasses which have a [flash point](https://en.wikipedia.org/wiki/Flash_point) or [autoignition temperature](https://en.wikipedia.org/wiki/Autoignition_temperature) like [Carbon disulfide](https://en.wikipedia.org/wiki/Carbon_disulfide) when exposed to extended sunlight the heat concentration on the flesh could have the potential to ignite. ]
[Question] [ In my story, I have two huge generation ships racing each other to another star system. Assume they are on an exactly parallel path, neck-and-neck, about one astronomical unit apart. They are traveling at exactly the same speed - point eight cee. They know the other ship is there, somewhere. They launched at the same time, although from separate in-system facilities. The form of drive is important. They are traveling in a modified Alcubierre drive - that is, using the vernacular, they are in a space-time bubble that preserves relativistic effects within the ships. The drive creates a low-pressure space-time area in front, and a high pressure space-time area behind. The drives also interplay with the Higgs field to reduce the effects of inertial mass. Thus, the bubble is effectively 'surfing' through space, being pushed by the high pressure from behind. Sort of like an airplane stays in the air. There is no intention to use the system to go faster than the speed of light, just close to it. Because of this, the ships are huge. They have huge fusion reactors, and a complete physics laboratory. Power is not an issue. They each carry tens of thousands of people, and have academic institutions that train new physicists born on the ships. Think in terms of a complete city. Knowledge and the ability to build new equipment is not a problem. The question is, traveling at such extreme speeds, wrapped up in a bubble, can they communicate with each other? If so, then how? Because they are adversaries, there are no entanglement possibilities between them. Some additional background to consider - light takes about 500 seconds to go one AU. The trick is not in the relative speed between the ships, but that they are both traveling at point 8 cee relative to where the light was first emitted. That is, there would be a Doppler effect as the light arrived at the other ship. The point of protecting the inhabitants from relativistic effects is that I sincerely doubt biological processes could function in the relativistic effects of point 8 cee. For consideration: Would there be a null point in the bubble between the front negative pressure and the rear positive pressure that could be used? A point of physics. When you project a beam of light from a spaceship, the point of origin effectively drops dead. That is, the beam origin does not gain or loose momentum from the spaceship. At the point in space-time where you 'drop' it, it stays there. Perfectly dead in the - well - space-time. The ship continues on. It does not 'follow' or 'trail' the ship. If you beam it behind you, then you travel away from the originating point of the beam, the point of origin just hangs there, and the speed of the light is determined relative to that 'dead drop'. Not the speed of the ship. Not the speed of anything around it. If it is a completely uni-directional laser beam, and it comes out the extreme rear of the ship, the ship occupants will never be able to detect it unless they come around. Baring gravity, it goes in a perfectly straight line from the original point of origin in space-time. **Please Note** I use point 8 cee because **c** is constant in all inertial frames, but the speed of a spaceship certainly isn't. I use cee as a unit of speed, as in miles per hour. [Answer] ## They totally can They may travel at extreme speed relative to their departure/arrival/medium in-between (think space dust), but relative to each other, they are mostly immobile. So any communication device able to cross 1AU (like a simple radio or laser beam) would do it, their "speed" doesn't matter. However, the Alcubierre bubble is another story. Since it's a fictionnal device it's hard to predict, but since it's your story, do what is convenient for you. My intuition would be that the bubble effectively distorts the signal, kind of like how light is distorted by the refractive index of water, especially if the water is not still. But I believe that, using this bubble as a drive, your colonists have it fine tuned and can precisely compute the distortion effect, and reverse it to get a clear signal. So, speed is not an issue and the bubble problem can be circumvented. The fact that you state "They know the other ship is there, somewhere" would tend to assume they don't know exactly where the other ship is but let's face it : at 1AU apart, with really big ships, it's not that hard to find each other. And once they do, they won't lose track of the other ship. Therefore aiming a radio signal is not an issue either. [Answer] # Maybe. Everything inside an Alcubierre bubble is causally disconnected from everything outside the bubble, but only if you're going faster than light. Since you mentioned that you're using subluminal velocities, you're not causally disconnected from the rest of the universe. You are surrounded by a bubble of compressed space-time, however, and that's going to give you some problems. It's easily observed that compressed space-time refracts light passing through it. This is going to pose some issues when you try to project something out of the bubble. Since this bubble is going to be concave around the transmitter, it's going to tend to diffuse any transmission out of the bubble, so the signal is going to have to be both extremely strong and very concentrated. It's also putting off some serious radiation from the front end, so you'll need to compete with that to get a signal out. # But this is science *fiction*! Well then, let's say that you can manage to get a signal out of the bubble. Making the problem worse, the universe has stuff in it [citation needed]. This is probably going to be a fairly lossy connection, so you're going to have to figure out a way to deal with interference and lost bits. These are surmountable problems. --- # So actually, let's not use a transmitter inside our bubble at all! I posted this answer too soon, and I've just thought of a fairly novel way to approach this. As I mentioned earlier in the post, the bubble is creating a great deal of radiation. Maybe we can harness that! Let's turn our entire ship into an AM transmitter! I'll be the first to admit I haven't slogged through the math on this one, but I'd put some money on the fact that increasing the speed of your bubble will increase the amount of radiation being emitted from the bubble. So if you can effectively modulate the speed of the ship, you can modulate the energy of the radiation! Now once your message reaches the other ship, the problem posed by the bubble actually becomes a benefit! I can't speak to the actual shape of the bubble, but I'm betting it's roughly spherical (in the front that is). The back is under negative pressure, so that's going to mess with things, but if you can use the front of the bubble to refract the signal back in towards the ship, you may actually get some gain. Beware that if you're looking for hard science, this last paragraph is rampant speculation, and I'd recommend you move over to the physics stack exchange to get some answers there. [Answer] **They can if you say they can.** The [Alcubierre bubble](https://en.wikipedia.org/wiki/Alcubierre_drive) is a mathematical solution consistent with the Einstein field equations, but that solution may not be physically meaningful. Even if it is, it requires negative energy to create, and we have never seen negative energy. Negative energy may not be possible within the laws of physics. There is so much uncertainty about how a real Alcubierre drive would work, that you can fill in a lot of the blanks however you like. I can imagine that radio waves pass through the bubble without any issues. The two ships can have a high bandwidth connection, albeit with an 8 minute delay due to the 1 AU of distance. I can imagine that the Alcubierre bubble scrambles all radio communications in or out. If we assume that the radio waves are transmitting a digital signal, the 1s and 0s might have to be very long and sent with a very powerful antenna to be received. Otherwise the radio signal gets lost in the radio noise. You could also say that the Alcubierre bubble gives off a lot of EM radiation (radio waves, micro-waves, light etc). This could limit the two ships to text messages as opposed to Skype calls. I can imagine that the Alcubierre bubble completely destroys all conventional EM signals. If this is the case, you could use your warp drive to vibrate your bubble in something akin to morse code. The other ship could detect the vibrations and decode them into a text message. This sounds expensive, slow and risky, only to be used in a dire emergency. [Answer] **You're using one mathematical concept that doesn't completely fit with our empirical universe, so let's use another.** [Tachyons](https://en.wikipedia.org/wiki/Tachyon) are theoretical particles that travel faster than the speed of light, which (I think) overcomes all the intrinsic problems associated with the Alcubierre drive. **But what about causality?** *Disclaimer: I am not a theoretical physicist. If a PhD in physics suggests that what I'm about to say is hooey, I defer to their judgment.* In the examples of communciation using Tachyons (such as the [tachyonic antitelephone](https://en.wikipedia.org/wiki/Tachyonic_antitelephone)), the example is always communication between one relativistic position and one non-relativistic position... allowing (theoretically) the message to be received before it was sent. However, I've not found (and didn't look hard for) an example of communiction between two relativistic positions. In the case of your ship, *both ships are moving within the same intertial frame despite being physically disconnected.* Due to this, causality should be preserved (IhopeIhopeIhope). ]
[Question] [ **This question already has answers here**: [Are geographically typed planets realistic?](/questions/40/are-geographically-typed-planets-realistic) (6 answers) Closed 6 years ago. I know this may seem like an obvious no, but with the newest *Star Wars* movie just released, there is a mineral-rich planet called Crait which I have seen make a few debates about whether or not this is single-biomed or not? Sticking to the World-Building community however would it be possible, given ideas like extreme rotations of axis vertically, or unparalleled atmospheric conditions that such planets could be scientifically proven to theoretically exist? Bonus question: If so, could there be a variety that could sustain life and how? [Answer] # Yes. There are examples of this in real life, that we know of. In fact, basically every planet that we know of other than Earth is a single-biome planet. Mars is a freezing desert planet, Titan is a hydrocarbon snow "planet", Venus is a crushing, superheated, acidic hellscape planet, Io is a volcano "planet", and there are a number of airless dust 'planets' like Mercury, the Moon, and a number of the larger asteroids and moons. Of course, none of these planets are habitable, barring the construction of sealed colonization buildings. [Answer] To give your question a sociological answer rather than a geographic one, I think it's possible to have planets with multiple biomes which are, none the less, known as single biome planets. For example, take Africa. How many distinct biomes, cultures, and governments exist in Africa? And how often do people think of or refer to Africa as a single, homogeneous place? It's far away, and we don't consume very much media that is produced there. It takes a lot of effort to have a nuanced view of Africa. That tendency to simplify places which are foreign to us is going to be so much stronger in a galactic empire. Every planet is going to be reduced to a tag line. Desert planet. Ice planet. Jungle moon. Lava world. [Answer] Yes but your planet will only have primitive lifeforms. For ex: ## Ice planet with liquid ocean under the ice crust: Imagine an ice planet with an active core and volcanic activity really far from its sun. Such a planet would have a 10km thick crust of ice under which there is a liquid ocean. The core of the planet is hot enough to melt the ice crust but because the planet is too far from the sun, its ocean is frozen on the surface (~ -200C surface temperature). Because the core is active, there is volcanic activity. Hydrothermal vent (underwater volcanoes) activity forms oasis of lifes. They provide heat and nutrients. Life is not based on photosynthesis. The deep-sea organisms living on your planet have no access to sunlight, so they must depend on nutrients found in the dusty chemical deposits and hydrothermal fluids in which they live. You basically only have 1 biome on this planet. Since the energy doesn't come from the sun, being at the poles or equators doesn't really matter. Seasons also don't matter. The only thing that matters is if you are close to a hydrothermal vent. Some researchers think Europa or Io could be like that. ]
[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 6 years ago. [Improve this question](/posts/89685/edit) One of my characters is stranded in a forest with almost all of of her belongings, and she must travel the 40 kilometers (~25 miles) on foot to reach her destination. She leaves most of her things behind, taking only the essentials/things she'll need once she reaches her destination (--her belongings consist **mostly** of what the average teenager might pack for a boarding school--she takes her phone charger, deodorant, most of her packed daggers, and two changes of clothes. These are carried in her backpack.) She also has archery equipment and a short sword and several throwing daggers on her belt. But she can't bring herself to leave her bear pelt behind--it's her equivalent of a teddy bear, and she's stubbornly sentimental. So she drapes it over herself like a cape (the bear's neck is cut so that it fits snugly over her head) and begins walking. Female black bears can weigh between 100-250 pounds, and males 130-500. These numbers are for fully intact bears, though. **I can't seem to find any reliable info on one that's been skinned.** I would rather the pelt be of a male bear but if it's unfathomable that the heroine could manage it I'm okay with it being female. It's late August, the climate in this particular location in the world at this time of year ranging between 24-29 degrees C (75-84 F). Our heroine is an eighteen-year-old demigod who's been training her entire life. There is no time limit--she can take as many breaks as she needs. Should she run into a combat situation, she would remove the hide. **How heavy is the pelt, how quickly would one dehydrate themselves / die of heat stroke (assuming she has an unlimited water supply) and how likely is it that she'd survive the 40km walk?** [Answer] **Black Bear Pelts can be between 21KG and 27KG** Depending in the size and treatment to cure the leather. An US soldier carry 60% of their body weight in equipment for survival when deployed. In the case of the girl, probably depends in her weight. Most 18 years old girls would weight between 46KG and 55KG depending in her complexion. What means that only the pelt would be 50% of their total weight still missing their equipment and weapons. **Dehydration Progress** Dehidration it's a process at a 2% scale your body begins to make you feel thirsty, mental and physical decay can be noticed already in decision making and reflex. At 4% begins headaches, dizziness and vomit. Mental process decays even further. Trekking in the mountains with over 35kg of gear and covered in a pelt during the day would mean a rest of 20 - 30 minutes for every 1.5KM to maintain some level of battle readiness and avoid a heatstroke. [Answer] I don't see this as too much of a problem for the Heorine for a number of reasons. Assumption one: She has been training with weapons. I'm guessing she is in pretty darn good shape. When you get right down to it, 40 km isn't really very far unless the terrain is really rough. That's for big fat guys like me. For an in shape 18 year old? No problem Assumption two: If she has had weapons training, she will probably have more than just a clue about roughing it. The Military has to move from point a to point b and finding big enough hotels along the way isn't easy. So she knows how to camp and has survival skills. As a Result, keeping the pelt is a no brainer. She would likely sacrifice a change of clothes in a heartbeat to keep the pelt. You can wear it, use it for ground cover, as a blanket, and so on Assumption 3: She has knives. If the bear pelt won't fit easily into her backpack, she will be able to fashion some way to carry it, with creepers, vines, whatever. Roll it up, a fairly small bit of cord looped through backpack straps, and problem solved. Assumption 4: wearing the thing, in relatively warm summer weather, is going to last about half an hour before she takes it off and rigs a carry device. The fact that it's forest, and likely to have lots of shade may mean she wears it for a couple of hours. She will also probably value freedom of movement and so not wear it in favor of free movement. Besides the bear pelt, she isn't carrying a ton of mass. At age 18, physically fit normal young women often make it through US Marine Boot camp and hike a lot farther carrying a lot more gear and do it with a time limit. This is a final step in Marine Boot Camp [The Crucible](http://recruitparents.com/bootcamp/crucible.asp). 45 miles in 54 hours with both food and sleep deprivation, in full gear with heavy rucksacks. This happens in the full summer too, with temps approaching 35C. A Demigoddes is not going to have any real issues. To her, this is akin to locking your keys and cell phone in your car and having to walk 3 miles home. That is aside from monsters or other attackers. A massive inconvenience, absolutely. Life threatening crisis for her, not at all. Now if our heroine was 12, it would be a different story. She would not have the stamina for it, and the psychological burden may be really bad since she wouldn't have enough experience to systematically overcome the problems. At that age, the pelt may be a very significant teddy bear indeed. Darnit, the setup description makes me want to go camping now. :) [Answer] According to [these guys](https://www.24hourcampfire.com/ubbthreads/ubbthreads.php/topics/6404841/Re_weight_of_avg_bear_Hide), it could be between 22kg and 27kg **with the skull still attached** but that it depends on the bear's species, which makes sense to me. I will be conservative and round it to 20-25kg with the skull removed. So that's at least 20kg of leather and fur covering most of her body, in a forest setting with a temperature between 24°C and 29°C. Reegarding dehydratation, I believe it won't happen if she has an unlimited amount of water. Besides, if she needs to fight, she might not have the time to remove the hide. The thing you describe looks like a 20kg - at least - sweater. I don't believe that someone suddenly realizing they are under attack would have the time to remove such a thing. In the end, I guess her end would come either from being attacked by a wild beast while trying to remove her bear pelt in order to defend herself with her boarding school weapon kit, it from exhaustion after carrying a heavy pelt and various weapons for days with almost no occasion to dissipate heat. [Answer] In The Revenant, Leo DiCaprio wears a real bearskin coat that weighed 100 lbs wet. > > [Leonardo DiCaprio's 100-Pound Costume: 'The Revenant' Star's Bear Skin > Coat Is 'Real & Very Heavy'](http://www.starpulse.com/leonardo-dicaprios-100-pound-costume-the-revenant-stars-bear-skin-coat-1848550102.html) > > > I found this, googling bear pelt weight. <https://www.24hourcampfire.com/ubbthreads/ubbthreads.php/topics/6404841/Re_weight_of_avg_bear_Hide> > > Based on my hunt last year with a 6.5 foot blackie I would say: > > > 1. The hide and head will definitely fit in a 48 quart cooler. > 2. I carried the hide and head out on my hunt and I would guesstimate it was in the 50 - 60 pound range. > > > from <http://alaskablackbearhunts.com/bear-data-hunt-results-alaska-black-bears-charters-trips-lodges-hunting-craig-AK.php> > > They were both taken in the spring and one weighed 326 pounds with a > skull of 19 3/16", a hide of 7'1" and was 16 years old The other bear > weighed 342 pounds with a skull of 20 4/16", a hide of 7'3",and was 10 > years old. I wish we had the time to weigh all our bears > > > Let us say skull/head weighs 10 lbs. She is not wearing a skull, so 40-50. 40-50 is for a big bear. Let us say that this is a small bear or at least a small hide; a young woman does not need 7 feet of bear skin. Let us say it is 5 feet; calf length for a 5.5 foot woman. So 71% of 40-50 lbs = 28 to 35 lbs. That is a lot of coat. But you probably would not need to wear much else. And then it would be easy to cool off by leaving the front open. And then guys looking to illustrate the cover of fantasy novels will draw you. ]
[Question] [ I will be writing a short story about humans landing on an earth-like forest planet with a gravitational force of about 3 meters per second squared (In contrast, Earth has a gravitational acceleration of about 9.81 m/s^2). I need to find how the forest would adapt to the gravity - **namely the height of the forest canopy** (usual canopy height about 30-40 m) - and **the types of flora that would dominate the forest**. [Answer] 1. The plants would be stringy, flimsy, not having to develop fiberous strength higher gravity requires. 2. Leaves would be larger and less numerous. 3. You might have fewer woody trees and bushes, ecology probably favoring dense fiber over actual wood. 4. Grasses and low-growing stuff probably wouldn't be much different. 5. Lower gravity means thinner biosphere. Between that and the tendency to thinner, flimsier growth, your canopy height might not actually change. [Answer] Trees exist because, once a species of plant starts going up from the ground until it reaches a certain average height, it will have an advantage over other species, because it will be able to overshadow them and thus catch more light and deprive its competition of it. Individuals of the same species which have the capacity to grow a bit taller than average will, *ceteris paribus*, be selected for. So there's an evolutionary pressure to grow as tall as possible. For trees on Earth the theoretical limit of vertical growth is [between 122 and 130 m](https://www.livescience.com/14667-tall-trees-grow.html) (Earth's actual tallest tree is [115.8 m tall](https://en.wikipedia.org/wiki/List_of_superlative_trees)). This is given by how much energy it takes to take water up from the roots to the tallest leaves and the pressure that the tissues can sustain. In a planet with less gravity, trees could and would surely grow taller. They would also have to support their own weight, of course, so they would be as hard and solid as Earth trees. Plant life in jungles and forests organizes itself into levels, from the undergrowth to the tallest trees, and that would probably happen in your planet as well. Maybe, since trees would grow so much taller, there could be more, and more diverse, ecological levels. [Answer] Back a few years ago, I've found the "epona project" featuring a planet with roughly half Earth's mass, meaning less gravity. This low gravity may create more challenges which must be considered 1- Mentioned in [this project](http://worldbuilders.info/): Carbon cycle: A planet with low mass will have its geological activity subside much more quickly. Carbon-dioxide dissolves in the water and interacts with rock minerals, making carbonate rocks. Those rocks may be subject to geological forces (like magma heat) which releases it back to the atmosphere. When geological activity subsides, more carbon dioxide remains trapped in rocks. Plants need carbon dioxide for growth. Lower geological activity means less will be available to the plants. The assumption is that plants will evolve means for storing as much carbon dioxide as possible during the night and use it via photosynthesis during the day. 2- Atmospheric escape: (Not mentioned in this site), depends on the type of star the planet orbits, the planet's distance from the star, and the strength of the magnetic field. Less geological activity means a weaker magnetic field. Combined with lower gravity, the atmosphere will be stripped more quickly by solar wind. The plants must retain vital chemicals under a lower atmospheric pressure and that becomes more difficult as atmosphere wears-off gradually. The planet will start its life as an earth-like planet with a lower gravity, but over time, a new strategy to deal with those challenges must evolve. EDIT: Low planetary mass as you envisaged may be impractical and will lose atmosphere long before any life may have time to evolve. The only "way out" of this is to assume a much farther planet, like Titan - moon of Saturn - being so far that temperatures are much lower and the two negative effects are much reduced. In that case, water is no longer a vital solvent, and you must use more exotic things like Methane, Ethane and Ammonia... [Answer] Assuming the atmosphere has the same density, just on a slow rotating small planetoid. I'm not sure but i believe plants would be a few % bigger than on earth (specialy trees), I believe I have read somewhere that the most limiting factor on the size of plants right now is the ability to flow water efficiently through its body. Of course if you want to be 100% realistic, at 1/3rd of earth gravity the rotation would be slower as well, so a lot of ultraviolet rays will pass through what would be the atmosphere. So I'd suggest the plants to be violet-ish color and feed mostly on this source of energy and most likely there won't be much if any oxygen. [Answer] In short, there would be no trees, and your humans would die upon exiting their spacecrafts. Or in other words, such a planet cannot exist. The graviation that you wish to have is 20% lower than the gravity on Mars, which means that the atmospheric pressure is also comparably low or lower than on Mars. Let's not even consider petty details such as lack of oxygen, just the mere atomospheric pressure. There is no surface water on Mars, how come? That's because without sufficient pressure, it boils away. No water, no trees (or life for that matter). Unless of course, the planet is a desolate, dark, frozen block of ice, in that case the water obviously wouldn't boil away, but there wouldn't be much leeway for trees (or the development of any significant amount of life in general) either. ]
[Question] [ If an alien race had teeth that, like our, don't grow back, would they have toothbrushes and would they be even vaguely recognizable to us? Their civilization wouldn't seem totally foreign to us but when does something like a toothbrush come up because it is the best or most likely solution to a problem and when are we just so used to our human way of doing things that we have a hard time picturing doing things differently. Physiology: Humanoid with hands and opposable thumbs, similar lifespans Technology: On par or ahead of us, most materials are of similar abundance as there are on Earth Society: They maintain reasonable standards of hygiene, they have dentists (among other physicians). They need their teeth to eat and are susceptible to the same forms of decay as ours (or many other animals). Diet: They are omnivorous, there's not as big of an abundance of food as there is here so if it's edible, it'll be on a plate somewhere. Lots of root vegetables, some meat and other things that don't really fall into either category. [Answer] My rational guess is, the aliens would not brush their teeth. There are several alternatives to "brushing teeth", including wiping them, scraping, hard rinsing (sometimes with a disinfectant or antibiotic), flossing and picking (e.g. using a toothpick). Also for rinsing, frequent alcohol consumption can improve dental health; and that used to be extremely common amongst everybody (children included) when weak ale was consumed instead of water (water, contaminated by waste and refuse, made people sick: Weak ale, with about 1/4 the alcohol of modern beer, sterilized most of the bacteria, making it safer to drink: And better for the teeth. Many of the things we do, we do out of cultural inheritance; brushing is likely one of those: We didn't brush for 99% of the last 50,000 years (when we suspect modern rational brains first appeared). (See here for the [invention of the toothbrush](https://www.loc.gov/rr/scitech/mysteries/tooth.html) in China, 1498). We only began our current extreme hygiene and anti-smell rigor relatively recently; just a few centuries ago the idea that somebody had bad breath or bad body odor was seldom noticed: Everybody stank all the time! People bathed infrequently, and often not at all; they often wore perfumes and excess clothing to cover up their stink. It is entirely possible for aliens the idea of sticking a tool in their mouth, like a toothbrush, spoon or fork, repellent: We have seen similar reactions in human culture. Although the Chinese did invent the first toothbrush; notice that the Chinese eating implements do not get as deep in the mouth as spoons and forks: chopsticks barely make it past the teeth, they are intended to just bring food to the mouth, not shove it in. The Chinese version of a spoon does not enter the mouth, either: it is more of a small bowl with a handle; it also only brings the food to the mouth, but the tool does not enter the mouth. It is plausible an alien race, even looking like us, could be repelled by the idea of putting anything **but** food into their mouths. Toothbrushes only offer a slight mechanical advantage in cleaning the teeth and are not very thorough at all; it is why we are still encouraged to floss, and on top of that, need periodic cleaning to remove plaques. My point here is that brushing is obviously not the pinnacle in tooth cleaning, it is not the ideal approach, or the most efficient, or the most thorough. I imagine there are dozens of other ways to partially clean teeth, to the same extent or better, to prevent cavities or disease. A disinfectant/antibiotic rinse (like with alcohol, spit out), combined with tooth picks and/or flossing for the stuck bits, seems the most obvious for teeth like we have. With dozens of alternative methods that can be just as successful, it seems unlikely we humans and the aliens would both arrive at the same flawed idea. [Answer] As Green pointed out, we didn't need toothbrushes until sugar was added to our diet. It should come as no surprise that we have evolved to have teeth that are sufficient to withstand the rigors of living as a human being in our natural environment. It is only as we bent our environment to our wills that we began eating in a way that demanded tooth brushing. However, you point out that the aliens have dentists. While we did have doctors who worked on teeth in the past, the dentist as you and I think of them today operates primarily to prevent decay due to our diet and to manage damage when decay occurs. Their presence in their society suggests that they should also have to brush their teeth. Probably floss too. [Answer] ## If they have a diet that induces tooth decay, yes For humans, we need toothbrushes because our diet includes foods that induce tooth decay. Refined sugars are an especially strong tooth rotter. Dentistry as we know it today exists largely to stave off the effects of our diet. If these aliens eat something that rots their teeth, they will need something to remove whatever makes their teeth rot. [Answer] Baring some sort of technology or medical science that would make manually cleaning teeth (or equivalent) obsolete, I sure aliens would have a number of specialized tools for cleaning themselves. But as for a toothbrush itself, it really depends on the anatomy of the alien in question. Asking that is like asking if aliens would use toilet paper or not. The true question is do you *want* aliens to use toothbrushes in your story? In the novel "Prostho Plus" by Piers Anthony, a human dentist is abducted in order to give aid to a race of aliens who communicate by chewing on soft sticks with specialized teeth and reading the brail-like markings. After being sold to a couple of Space Whales, he treats the numerous cavities of their massive child, whose diet is mostly sweets, by working inside of the being's mouth. ]
[Question] [ In [his answer](https://scifi.stackexchange.com/a/132931/38409) to a question on our Science Fiction and Fantasy SE about how Westeros in Game of Thrones produces food during the winters, [Superbest](https://scifi.stackexchange.com/users/21204/superbest) says: "Martin's conception of a multi-annual winter is a little bizarre in my opinion. If this has been going on a geological time scale (eg. millions of years) it would either create flora and fauna radically different from what we see here on Earth, while the novels seem to portray basically the same animals and plants we have, with the occasional exotic exception". So, how would an animal evolve to survive on a planet where [winters and summers lasted varying, random lengths like in Game of Thrones](https://worldbuilding.stackexchange.com/questions/176/is-it-physically-possible-for-a-planet-to-have-seasons-of-different-lengths)? What common traits would develop among animals in general? (I know there would be wild differences based on predator/prey status and such, but there would also be similarities - what would they be?) Assumptions: Winters can last anywhere between 1 and 30 years at a time. 99% of the time it will be somewhere between the 2 and 10 mark, however. Summers work the same way, with summer instantly kicking in after winter ends. The length of a summer has no relation on and in no way impacts the length of a winter and vice versa - it is totally random within the above parameters. We will also assume that this world has obviously been like this for long enough for animals to evolve, if not from its beginning. Edit 1: The sun remains in "summer mode" for the duration of summer, and "winter mode" for the duration of winter in regards to the length of the day. It is also, obviously going to be horrendously cold for the duration of winter in the northern hemisphere. Outside of this, the world is exactly like Earth. [Answer] I have always thought of the Westeros cycle as more like climate change than like seasons. Specifically, there are seasons, just like in Europe or North America, and *superimposed over* the annual cycle of seasons there are climate oscillations induced by some kind of oceanic phenomenon, somewhat similar to the El Niño / La Niña phenomena on Earth. The transition from a warm period to a cold period may be very short or it may last a few years -- my impression from the books and from the TV series is that when winter comes the years get progressively colder, but then I may be wrong. It may be that such a world will give preference to hardy animal and plant species which can survive both cold and warm times. It may also be that some areas are always cold and some are always warm -- for example, the area beyond the wall seems to be always cold and the areas inhabited by those barbarian nomads and amoral slavers seem to be always warm; the areas in between would then be colonised by cold-loving species in cold times and by warmth-loving species in warm times. Probably a mix of both. The main threat posed by cold spells in Westeros (forgetting about undead foes) is that agricultural output collapses, as expected. The long winters are times of hunger. Think of how many animal and plant species can be found everywhere from the Artic Circle to the tropics: fir trees, and deer, and wolves, and grasses, and birds. They may dominate the north and be restricted to higher altitudes in the south; they may thrive in more temperate areas and be restricted to favorable locales in the north; but definitely there are plants and animals which are (or would have been in the absence of humans) common to all Europe, from cold Norway to warm Italy or Greece. [Answer] Unpredictable winters mean you need to be ready for them at any given time. I guess plants would have weak fast growing branches with thin leaves or something. They're easy to grow and not a huge loss if frost suddenly kicks in. Then when it's cold you hibernate. Same goes for animals though I don't think a single complex organism exists that can hibernate for years. Tardigrades totally can but they're not that complex. They build wouldn't work for a more advanced creature like a primate. I actually think the whole setting would exclude the evolution of advanced fauna. Flora will be things like trees that can survive outside combined with plants that use an extensive root system to survive the cold. This can't support large animals as there would be little nutrients above ground. Smaller animals could probably survive if they produce very 'expensive' eggs that can hibernate through winter. Probably buried underground. Animals living short lives while they pour all their energy into hibernating eggs who would emerge at first spring. Of course there is one exception, the ocean. The water would largely nullify the effects of the winters. Underwater you'd have a teaming ecosystem. [Answer] Flora Trees - Pine trees and other coniferous trees are actually already decently suited to this setup. Their seeding usually depends on fire and not a normal spring thaw seed that many other plants use, which means prolonged winters are not a threat to their reproduction. We already see much of this in the north. That said, these trees need the root structure and therefore can't survive in tundra/marsh and will be more common in mountainous terrain. Trees that loose their leaves wouldn't fare well in this setup. Bush/shrub. Take from the current tundra, there are some hardy plants out there. Moss and the sort also tend to do quite well out here. I believe you will see some berry plants (wild blueberry) capable of surviving the elongated winters as well, some adaptations to the seeds to stay dormant until the summer phase appears will likely allow for berries to exist in these setups. I don't think 'raspberries' and other semi-permanent bushes would do well. In both the cases above, it's likely these plants will support very expanded root systems for storing reserves through the elongated freezes. Animal life I believe hibernation is out as a survival technique...the lack of definite summers pretty much rules out the store up fat and sleep option simply because the animal has no ability to guess how long it would be asleep for and how many reserves it would need to build up. Life on land under ice - Ice is actually an excellent insulator and even in extreme cold, under the ice can still be inhabitable. Given the prediction of the expanded root systems, there should be additional nutrition to be found under the ice. Lemmings and other rodents could survive under the ice along the southern areas of this winterland. Life on the land, herbavores. Migration has always been a valid technique for animals. That being said, it's 'seasonal' migration based on a constant cycle...if the season instant predictable, then these animals are going to need to adapt and find food locations during the extended winters, while still having a trigger to go back north. If there are larger herbivores wandering around the region, they will likely be migratory. Life on the land, predators. I believe wolves living on the southern areas hunting both migratory and creatures under the ice should be able to adapt to these situations. Life on sea ice. Honestly, I don't think theres much of a change in behavior here. If you have frozen over sea water, life on and off the surface will not have the cyclical nature it currently does, but I suspect the life (seals/fish/whales/bears) would not be greatly effected. Side note: I live near the rocky mountains and am very familiar with the spring melt off. Winter snow packs up during the winter and when the warmer temperatures come, the water melts and the rivers greatly increase in volume and speed. With some rains added, we've seen some vicious flooding over the last decade. I would imagine a prolonged 30 year winter cycle jumping straight into a summer cycle would create some outright vicious flooding as the snow pack melts...rivers seeing 50x volume and low laying areas becoming completely waterlogged. [Answer] Maybe I've got a different conception of what the seasonal changes were in Westeros--but from reading the books, it seemed that they still had the yearly 4 seasons, it's just that the temperature and rain fall would be higher or lower for a number of years, based on whether it was in years of Summer or Winter. So like, in a Winter year, the summer would still come, but it would be shorter, and the temperature would never climb to record highs in a Winter year. It also seemed to depend on where you were--so in the South, it would never be as cold as it is up North. I thought of it as a large meta seasonal change that they noticed--normally in the South, it doesn't snow (just like say, Atlanta) but every once in a while, we get surprised by a snow--but in Westeros, they know that it's going to colder than it normally would be and there'd be a chance of snow in a very Southerly area--and they know it's going to be during a Winter cycle, most likely Winter/winter, or during winter season in a Winter year, especially if it is forecast to be a harsh one. It seems to me that the temperature ranges are within acceptable parameters as far as evolution is concerned. That being said, let me get down to your question: * knowing when to leave and where to go. Migration can be very helpful. * mammals have the advantage. but lizards need to be able to hibernate for decades if at all possible. * plants have got to be tougher and be able to grow and flower more quickly to take advantage of the small windows of optimum temperature and sunshine during a "Winter" year. They also have to be able to re-grow and go dormant if needed. I honestly don't think life would be all that different, except that animals and plants would be tougher. ]
[Question] [ A man with high political ambitions tries to rise to the top by using his special ability: memory manipulation. How can he successfully use this ability to rise to the top of his kingdom/Empire? **How the power works:** The power affects the part of the brain in which memories are "saved". For it to work, the user needs either 1. eye contact with the target or 2. physical contact with the target. The user can only work on one person at a time, meaning that mass hypnotizing is out of the question. But once the user has altered someone's memories, those stay altered. The power can fail if the mind of the target views the memory that was implanted as "unnatural" or "strange". [Answer] So for this to work, he would need to do some prep work himself. He would need to find a noble with a decent amount of political pull. Bump into him a few times walking around. Walk past him so he sees you. This will establish that he knows you from some where. When you go to implant a new memory, it won't seem foreign because you already established a natural memory. Once you plant a memory, you use your connection with him to get into places otherwise would be VIP restricted. Political parties, political events, invites you tocome with him to dinner parties of higher ups. Use him to gain natural networking for other people with more influence. Once he has served his purpose, you go on to the next person who holds more political say and whom you have become close with. Plant a memory that you are someone of importance and have him then vouch for you as he takes you around doing the same thing. The only catch that we don't know is if when he switches people, does the memory then fade? Even if that was true, he should still retain the natural memory you created with him and he will just think it's a brain fart and he forgot about that moment in time. Once he has gained enough noble and political support, it should be fairly easy for him to then make a move and gain highest political prestige! [Answer] Well, one method would be for him to start trying to pit the higher ups against each other so he can rise up by making each of them think that the others are starting to conspire against them, making certain people forget things like dates, deadlines, etc. (this can cause a lot of chaos by making people unable to coordinate, but do it too often and they'll get suspicious and/or start writing things down more often), and/or by inserting little memories making himself look more trustworthy. The key point would be for him to have answers that don't seem too convenient (or to change the minds of anyone who thinks he does) to all the problems his memory tampering causes and for him to portray himself as being overall more competent, but not blatantly out for their jobs. This is definitely a long term strategy though, so if you need him to get into power quickly, you probably should choose something else. [Answer] Since it only affects one person at a time, he would definitely have to use it sparingly, and on important people. Make them think they agreed to meetings, agreed to donate to his campaign, agreed to place him in important positions. Also, is there a way he could possibly *create* something, or have something created, that would help him use it for mass hypnosis? Then, at rallies and such, he could plant memories in the crowd's minds of his opponents saying and doing horrible things, and make them think they had planned to vote for him all along. Of course, all of this only works in a voting society, and since you mentioned nobles, I'm not quite sure that's what you have. If it's *not* a voting society, and it's the king, or nobles, who decide things, then he could work on them in much the same way. To counteract the "will-reject-if-memory-seems-strange" part, he could maybe alter memories a little at a time? Like, he can't just make the king think he promised to hand him the throne, 'cause that would be weird, but he *can* make the king think, slowly, that his heirs are untrustworthy, that the only one who *can* be placed on the throne is this fellow.... Those are just my thoughts, I hope they're helpful to you :) [Answer] There are many ways for your protagonist to rise up. For example, he can work his way into the royal palace (shouldn't be too difficult with his power), and once there, make an eye contact with the king. Then he would plant a memory that the king had a long-lost son, and he is this son. [Answer] Memory manipulation is a power with great power to destroy people's lives, and advance your own. Consider: * As a child, your greatest competition in school is given false memories about the things he is learning, and fails an important test. Even if they learn they were wrong, it's too late to fix. * At a more subtle level, being able to make someone remember something real in a slightly different way can affect the way that person perceives you. Suddenly you are trusted as a humble, kind, and generous person, when you are none of the sort. Friends are easy to come by. * Later in life, anyone you perceive as a threat (or even as serious competition) would be vulnerable to accusations from people with false memories. They could be thrown out by a spouse for adultery, or even falsely convicted of crime. * If you want to commit a crime yourself, it becomes trivial to set someone up as your alibi with this power. And even if you were caught and imprisoned, you could probably convince your jailer that you were improperly jailed. [Answer] I'm going to go a different way from the other answers and say that, in addition to influencing powerful leaders, one of the most important things is being able to **touch and make eye contact with as many people as possible on as regular a basis as possible.** Does your city have an entrance gate? DMV-type citizen registration system? Regular census? If not, use your pull on the most influential people in government to make this the case, and make them make YOU the person in charge of it. If you want ultimate micromanaging control, here's the best strategy I can think of: 1. Use your power to convince the top doctors and officials in the country that there is a horrible disease going around and that the only way to contain it is for everyone in the city to get **treatment involving an eye exam at least once a month** (or whenever the government tells them to). 2. Make them **put you in charge** of this! You're amazing and the most capable person they know! In fact, remember when you handled that other amazing thing that was just like this? Well, now they do. 3. Set up a system where **you can look into the eyes and touch anyone who you want** on a regular basis, or on demand. If you want to make it look really legit, you can have a bunch of lackeys that "examine" the people you don't care about, while reserving the really important people for yourself. The key is being able to not just modify memories once or twice, but to constantly keep them up so that no one gets suspicious. You will be limited only by speed with which you can modify their memories, and perhaps being able to keep track of whose memories belong to whom. By convincing people they were really sick before they saw you and feel better afterwards, you can set yourself up as the hero and sole savior of the new world. Enjoy! [Answer] The power can be used to ensure he is given credit for major successes and is seen as the fair recipient of benefits, by courts, powerful people, and so on. In most countries, power is closely related to money, and those who don't have large-scale power already, may gain it through their money and business influence, this seems a good place to start. Also it means he doesn't need to influence many people, or obviously, which is going to play to his strengths. ]
[Question] [ Imagine a gigantic cube 5 times the size of the sun and 5 times as massive ramming its way Into the sun, would the sun just explode or fade out as its smashed by the ram? \*please assume the ram object is impervious to damage [Answer] I'm assuming that by '5 times the size of the sun' you mean 5 times the effective volume, not 'with a width 5 times the diameter of the sun'. I'm also assuming that the ram is moving implacably through the solar system perpendicular to the plane of the ecliptic and has some motive force that will carry it on that path after collision rather than stopping. With that out of the way: Your cube is the same density as the sun! Hooray! Not that it really matters. What matters here is mass: Your cube will start to affect the sun long before it reaches it, pulling the sun, the planets and basically everything in the solar system out of their positions. Before this cube gets to the sun (depending on its exact velocity) we can imagine that the planets will be sucked inwards and upwards towards the combined centre of mass of the sun/cube system, resulting in them potentially being: A: Thrown out of the solar system B: Crashing into the cube C: Crashing into each other D: Miraculously still orbiting something resembling the centre of the solar system, just in much crazier orbits Needless to say even the approach of the cube has destroyed the solar system as you know it. Then it gets close to the sun. The first thing to note is that you said the ram is impervious to damage. I'm going to take that to mean it reflects all energy that hits it. This is hilarious for a few reasons: 1: The cube will appear very bright and will get brighter as it approaches 2: The reflected radiation from the cube will hit the sun again, meaning that as the cube approaches the sun the sun's own photosphere will start to be blown off *by its own solar wind*. The sun will also start to oh-so-slowly move away from the cube, propelled by it's own power (stellar fission rates behave weirdly with regards to temperature, but as a general rule more energy in an area leads to higher rate of fusion. 3: The solar wind reflected from the cube will start to push on the planets from an unusual direction, adding yet another vector to their orbits and playing merry hell with their magnetospheres. Expect some utterly astounding aurora. Then the cube hits the sun. Again: the exact effects differ depending on the speed. Either it will be a relatively slow impact (below the escape velocity of the sun from the cube) with the sun spreading evenly across the face of the cube before 'running' off the edges or it will be a spectacularly energetic affair that causes the sun to 'splash' parts of itself away from the cube and into the interstellar void. Both of these will make the sun temporarily brighter as the sheer amounts of energy involved (and a lot of photons trapped in the sun's vast bulk) are liberated in the form of heat and light. In either case the sun will lose the density it requires to maintain a stable fusion reaction. It will either do this because it's just been smeared into a thin cloud of hot gas by a high velocity impact, or it will do it because it's core has been replaced with an inert block and it is now a 'sea' of stellar elements (hydrogen, lithium, oxygen, carbon, a few heavy metals because it's a few generations old) surrounding the cube. In either case it goes 'dark' again, radiating only infrared. And your cube continues on its way to who knows where. So the answer to your question is: *It depends. **How fast is it going?*** ]
[Question] [ Would it be at all viable for a person to have certain plant characteristics such as: * Chloroplasts in their hair and skin, with the skin maybe lookmuch darker because of extra light absorbance (maybe a special skin pigment to absorb the green light the chloroplasts don't). * An ability to become relatively inanimate, shutting off most human characteristics and surving on the plant ones. * If they have energy reserves the ability to start to grow 'roots' out of their skin which can absorb substances in the ground. The person still has all basic human characteristics and would still eat but would be able to survive on less and gets extra energy, or in 'shut down mode' all energy, from their plant like features. I know that the surface area to volume ratio is a problem if the person is active, that is why they would normally still eat food. Essentially this is for a gardener character who is **very** at home in their employer's garden. Is there any way to make the person more functional and plausible? Any more plant features that would help them be more plausibe? [Answer] Suggestion: **These abilities come from an engineered symbiote, not engineering of the person** The other answers cover why GMO humans are a complicated issue. That said, it can be somewhat sidestepped. Instead of engineering the person, engineer a symbiotic organism that's compatible with them. It's not unheard of - After all, the bacteria in our gut are symbiotes that break down food for us, and the Mitochondria in every cell of our body is arguably one, too. A big problem would be the persons immune system fighting back against the symbiote, seeing it is an invading parasite. Maybe this organism is closely engineered to pair with our immune system, or maybe the gardener was born very immunocompromised and was a perfect candidate for the symbiote. As for specifics on what exactly this thing is, I'd imagine that it's a subcutaneous fungus that ties into the hosts bloodstream. The fungus gets access to all kind of exotic animal-only proteins, and in return the human gets constant glucose production. To make things better, if the fungus detects stress-hormones in its host (Injury, shock, etc,) it can put the host into a deep, low-energy-consumption trance to heal (Additional points for tree-sap base blood clotting factors to seal wounds.) Since it's a genetically separate organism that doesn't touch the reproductive organs, our human is free to reproduce - if they can find a partner willing to accept their odd skin tone. [Answer] You would have to include a **lot** of additional genetic information to make all the tweaks work. We are talking root level things like chloroplasts and circulatory system. It is extremely likely (like 99.9999999999999999999999999999999999999999%) that the tweaks would end up killing the person. While it is *theoretically* possible to build a creature with the abilities you have mentioned, the complexity of functions would make him/it extremely prone to debilitating diseases. [Answer] ## Short answer - yes, it's possible, but it complicates things. Check out [Old Man's War](https://en.wikipedia.org/wiki/Old_Man%27s_War) and its sequels by John Scalzi. It includes genetically modified human soldiers who are capable of photosynthesis, among other things, but a key point of the system is that these soldiers are too different from baseline humanity to ever reproduce. They're all sterile. The changes you're thinking of would be possible, but they would also be massively life-altering. A person who underwent these kinds of changes during their life would likely have to go through a long and difficult transition, and almost certainly would not be interfertile with the baseline population. You'd need to address questions like why a person would do this to themselves, or if they were born this way you'd have to address the ethical concerns of creating a genetically modified human who would never be able to engage fully in society. Unless you want to fully engage in those questions, whether with this individual or with other individuals in the same world, it may be something you just don't want to bring up. [Answer] you missed a few big plant features. 1. totipotency, plants can regrow anything. 2. plants can manufacture all the essential amino acids, much fewer problems with malnutrition. roots and photosynthesis are nice, but their effect will be minor on a soldier becasue they need too much energy compared to what these methods could generate. a person would need a 150 days of full sun over their entire body for evey one day of moderate activity. <https://hplusbiopolitics.wordpress.com/2008/08/12/photosyntheti-people/> [Answer] ## See my answer on "[Plant Based Life Forms: Brain Equivalent](https://worldbuilding.stackexchange.com/questions/58748/plant-based-lifeforms-brain-equivalent/58755#58755)" It addresses three ways of how plants and brains can evolve in one organism (or a symbiote) and could easily be adapted for a humanlike creature. I'll summarize the relevant information here but your best bet is the link above. > > **A)** Plant people could evolve from the very beginning: think person with chloroplasts > > > **B)** Humans mutate chloroplasts, and the fittest to use them survive until plantlike grows occur over generations > > > **C)** A plant and an animal form a symbiotic relationship > > > ]