Split (1)

train · 67.3k rows

text stringlengths 22 2.11M
[Question] [ I've been on a guns question binge lately, and this is no exception. Given my previous questions about [vanishing projectiles](https://worldbuilding.stackexchange.com/questions/54801/how-could-you-make-a-bullet-that-disappears-entirely-after-impact-like-ice-mayb) and [explosive alkali metals inside bullets](https://worldbuilding.stackexchange.com/questions/54491/potential-of-potassium-caesium-bullets), I started thinking of other chemical reactions, except this time not in the form of the projectile, but rather the propellant. Similar to how baking soda volcanoes or airbags work, using a catalyst and substance that react violently to each other utilizing valves that let only a certain amount mix could provide a very effective and quick propellant. The more explosive the mixture, the faster the projectile could be flung. This obviously leads me to my main question: Would such a system work for a chemically powered gun, and what mixture would I need to use to achieve it? Note: Per the comments, I realized I made a mistake. I'm not looking for fire-based chemical reactions, but there does need to be a reaction occurring, preferably with liquids. [Answer] I was thinking hydrazine, but when I went to research it discovered that the U.S. Military had beat us to it. You will want to refer to this wikipedia article on Bulk Loaded Liquid Propellents <https://en.wikipedia.org/wiki/Bulk_loaded_liquid_propellants> > > Bulk loaded liquid propellants are an artillery technology that was pursued at the U.S. Army Research Laboratory and U.S. Naval Weapons Center from the 1950s through the 1990s. The advantages would be simpler guns and a wider range of tactical and logistic options. Better accuracy and tactical flexibility would theoretically come from standard shells with varying propellant loads, and logistic simplification by eliminating varying powder loads. > > > In general, BLP guns have proven to be unsafe to operate, and they have never entered service. > > > Fuels tried: * solution of ammonium perchlorate in ammonia * mixture of 63% hydrazine, 32% hydrazine nitrate and 5% water * propylene glycol dinitrate with a stabilizer * 90% nitric acid and a proprietary hydrocarbon * mixture of hydroxylammonium nitrate, isopropyl ammonium nitrate and water [Answer] What you're suggesting - assuming you're restricting yourself to liquid propellants - sounds like you're basically doing the same thing as a rocket engine, but using the reaction to drive your projectile rather than propel your rocket - so presumably, what's good for rocket fuels would be good for your propellant, and you want something with a high specific impulse. I'm not a chemist, but I think hydrogen peroxide + a (might be platinum?) catalyst is one possibility. If you're allowing solid fuels, then you're back to existing gunpowder tech. You might also be interested in the Gyrojet - speaking of rockets :) The gyrojet was a gun that basically fired small rocket projectiles, rather than detonating stuff behind a bullet. Advantage was a lighter weight weapon (less force to contain in the barrel) and a lower recoil (since the rocket was still accelerating after it left the barrel). Disadvantage was that the projectile wasn't at max velocity for close targets. [Answer] If you do not want any form of combustion, i.e. a chemical reaction that produces heat and expanding gases, then the only other option is perhaps a compressed air gun, like an air riffle or a paintball gun. If liquid propellant is the requirement, then CO2 guns, including pellet and BB guns, as well as paintball guns, use canisters of CO2 which are compressed into liquid form. I am not sure if combining any such compressed, liquified propellants would cause greater expansion, providing more thrust, without some form of chemical reaction. As far as I am aware, any kind of chemical reaction that would aid in the process would have to be exothermic, i.e. fire-like. Alternatively you could choose another type of gas such as nitrogen or a noble gas such as helium, but I am not aware of any advantage this may provide as far as thrust, nor much if any advantage to do with environmental concerns, i.e. CO2 is already very stable and is not likely to produce immediately threatening reactions, such as fire, with other compounds in the environment. ### Otherwise More on liquid [high explosives](https://en.wikipedia.org/wiki/Astrolite). > > Astrolite is the trade name of a family of explosives, invented by > chemist Gerald Hurst in the 1960s during his employment with the Atlas > Powder Company. The Astrolite family consists of two compounds, > Astrolite G and Astrolite A. Both are two-part liquid-state high > explosive mixtures, composed of ammonium nitrate oxidizer and > hydrazine rocket fuel. > > > [Answer] Well, I have been wondering the same thing actually and I have come across multiple problems along the way. Pressure building up in the gun can result in an explosion due to too much pressure in an enclosed area. Also add that some of these chemical compounds can be dangerous to your team and/or environment. When you look at the big picture it really is useless depending on what kind of round you are using. If you were to just project a solid piece of metal then why not just use gun powder. But once you start using explosives or poisons of some sort, you really should consider using the possibility of chemical propellant. For example, Using a nuclear round (I know this sounds ridiculous to some) and regular gun powder will ignite the round just from the initial force, if you use chemicals to build gasses up it will be less harsh on the round and less chance of it igniting. Sure this is not accurate but it is a possibility. Conclude that it's not a "Need" but a want or wish for it to happen but the logistics say that it is dangerous and ineffective as a weapon. [Answer] Since it is not entirely clear what sort of reaction you are looking for, I will suggest "[electrothermal](https://en.wikipedia.org/wiki/Electrothermal-chemical_technology)" guns, an experimental technology which uses plasma to ignite or otherwise vaporize a propellant. Current ETC technology uses plasma igniters to more efficiently ignite a propellant charge, so in a sense it is still gunpowder technology, but using a different method of ignition to increase performance. To meet you requirements, some variations of ETC technology use powerful plasma ignitors to vaporize liquid propellants, including simply turning water or a water/aluminum slurry into a plasma to push the projectile down the barrel. This is closer in concept to a steam canon, except the steam is replaced with an energetic plasma. The muzzle flash must be truly impressive. Many of the liquid propellants noted in the other answers would probably work as well as or better using electrothermal ignition technology, simply because it should provide a more reliable and consistent ignition, and a longer "burn" to maximize efficiency. [Answer] two words: RAIL GUN. Ok, I know that with existing science it's totally impractical at this point because the current requirements and such make it so, but still... A magnetically propelled steel slug moving at 20 times the speed of sound. I do wonder what the purpose of an alternate propellant would be. Are you throwing an object with the notion of just hurting someone? Are you trying to crack fortifications? Is it for a totally multipurpose weapon? [Answer] Menthos + Cola. Allow the gas pressure to build up, then use it to propel a projectile. ]
[Question] [ [Proxima Centauri](http://arstechnica.com/science/2016/08/its-true-the-closest-star-to-the-sun-harbors-an-earth-sized-planet/) may have a rocky, earth like planet close to its dim sun. Tidally locked, the sun facing side may have a temperature up to 30 degrees Celsius and a dark side of -30 C. This would make one side temperate with liquid water, and the other frozen like antarctica - cold, but not unbelievably so. Assuming it holds on to its atmosphere, what sort of weather systems might we find on such a planet, where one side is perpetually day time (with moderate weather) and the other a frozen night? Taking this further, if I may, would we expect unique adaptations from life originating on such a planet? [Answer] The best way to envision such a world is with a coordinate system such that the south pole is always facing the sun, the equator is locked in permanent twilight, and the north pole is locked in permanent darkness and ice. Lets consider three parts of climate: sunlight, air circulation (which controls precipitation), air temperature. The big thing we are not considering is arrangement of continents which will have a big effect on everything. Sunlight Let us assume that total average solar irradiance is about the same on Proxima b as on earth. In that case, the south-pole recieves ~2.5 times as much sunlight energy than the equator on earth, since it is always recieving sun directly overhead. I don't know how to embed equations, but the math on this is that sunlight incidence for a single spot on the equator lasts for 12 hours a day, and is a sine function, starting at magnitude 0 at t=0 time units, peaking at 1 at t=1 time units and going back to 0 at t=2 time units. The total sunlight can be modeled as the area of a half-circle of radius 1, or 1.57 units of sunlight. Constant radiation at magnitude 1 for 4 time units would be 4.0 units of sunlight. At 30 degrees from the south pole (or 60 degrees south) the planets recieves 87%, at 30 degrees south 50% and at the equator 0% (also, obviously, the same on the dark side). Thus, everything below ~25 degrees south will get more more sunlight than the equator on earth, while above that point, sunlight rapidly drops to zero. The sunniest places on earth recieve ~8 kWh/day of sunlight, after counting for clouds, at the surface (those are deserts in the tropics). If we adjust the south pole of Proxima b to get a 10 kWh/m^2/day (which will be reduced by rainforest clouds to more like that of the earth's equator), then 60 degrees south sees 8.7 kWh/day (equivalent to Death valley in the summer), 30 degrees south sees 5 kWh/day (Chicago in the summer, or Miami year-round). At 10 degrees south gets 1.7 kWh/day (Seattle in the winter) which is barely enough to support plant life. Then all the sudden a the equator, the sunlight drops to zero. So there is a huge and sudden cutoff in sunlight energy. The photoperiod is the amount of time per day the enviornment is exposed to the sun. This is 100% for the interesting half of the planet, and 0% for the not interesting half. This would have significant effects on plants. Alaskan cabbages can grow hugely because of constant sunlight, and anyone from the north (Minnesota/New England) can attest to the explosion of green that long summer days bring. Air Circulation On the earth, the Intertropical Convergence Zone follows the sun's zenith point back and forth between the two tropics with the seasons. Air flows from ~30 degrees north and south of this latitude towards it, and then rises, causing low pressure and rainfall. Since the equator is never too far from the ITCZ, it is almost always getting rain, and hence rainforests. On the Proxima b, the effect is magnified by the fact that the ITCZ never moves from the south pole, but the low pressure effect is somewhat disrupted since instead of expanding to a greater area as the air masses move towards the equator on earth, they air masses are compressed into a tighter spaces as they converge on a single point on Proxima b. On the other hand, the area of rising air will extend farther from the point south pole of Proxima b than it would from the line equator on earth. Upwind, the Hadley cell will bring high pressures and lower rainfalls at 30 degrees off from the south pole, corresponding to 60 degrees south on our planet. Above that, the Ferrel cell will pull surface winds from 60 degrees south to 30 degrees south where that air will rise, and contribute to the Polar cell (note: badly named on Proxima b, since the polar cell actually concerns the equator here), that will suck surface winds from the twilight equator to 60 degrees south. The Ferrell cell, which is weak on earth, will likely be strengthened on Proxima b, since the sunlight is constant in the various parts of the planet. However, the precipitation effects of these cells would not be seasonal at all, since there are no seasons, so there will be no rainfall regimes equivalent to the summer-wet Savannahs or winter-wet Mediterranean climates of earth. Air Temperature The division of Proxima into circulation zones will have some interesting effects. The Hadley cell will recirculate warm/hot air from 60 degrees south to the south pole. The (adiabatic) compression as the air approaches the point of the south pole will probably result in higher temperatures, so that the rainforest center will be even hotter than expected. Rainforests have an average yearly temp around 26C on Earth, so this on Proxima b they might be more like 32C, the yearly temp in the deserts of Djibouti (total guess, no math involved). The Ferrell cell will bring the still warm/hot air temps from 60 degrees south up to 30 degrees south. The polar cell, on the other hand, will bring cold/frigid air from the equator to 30 degrees south. I would expect this to cause a sharp temperature grade at 30 degrees south. Put it all together At the south pole, and for ~20 degrees latitude (1200 miles/2000km) outwards is a rainforest, with constant clouds rain, and heat. On an earth-size planet this rainforest would be ~12 million km^2, bigger than China and more than twice the size of the Amazon, assuming it was all covered by land. The heat would increase towards the south pole so that the pole itself would be unbearably hot and humid for a human, or any sort of warm-blooded creature (assuming earth-like biology). This are would be a haven for insects, reptiles (Dinosaurs!) and amphibians. At this point the precipitation levels would drop steadily into barren conditions at the 60 degree south. The trees will gradually transition to evergreens that are able to retain water better. As he dense foliage thins out, eventually we reach a point where this is enough underbrush to burn periodically during week long dry spells. Then the trees have to be fire resistant and the ecosystem would resemble the evergreen thorn forests of India. The next step would be hot semi-desert like Arizona with its giant cacti, and then finally sandy dunes like the Sahara. Going from the dry zone back to the wet would be similar. Because sunlight energy is still high here, and warm winds are coming from the 60 degrees south belt, temperatures stay high between 60 and 30 degrees south. I mentioned that solar insolation at 30 degrees south was like Chicago in summer or Miami year round. Well Chicago in the summer is 24C, and Miami is 25C year round. So its still plenty warm around here. Infact, this region would be another rainforest, just like the tropical one, with constant moisture warm temperatures. However, with the reduced sunlight, it might favor coniferous trees over broad-leaved ones. Lower sunlight means slower growth rates, which might favor trees that can grow higher. The biggest trees on earth are conifers. After this there is a sharp temperature cutoff as warm dy winds rise over cold polar ones coming from the north. This sounds like a very stormy zone, with temperature fluctuations from hot to cold as fronts move back and forth, and massive thunderstorms. It should still be wet, but the trees must be adapted for periodic freezing temperatures. Then above the transition zone, the winds would bring nothing but frozen moisture-less polar air. Since there is still some sunlight, and it is constant, the soil should not freeze even if the air is frozen, and plants that can grow in near freezing conditions can still thrive, like mosses and lichens. This area would be an evergreen but cold tundra with temperatures oscillating around teh freezing point. After crossing the equator, the sunlight suddenly drops off to nothing and life ceases. The seas are frozen, and the lands buried in ice. [Answer] The coolest potential climates for tidally-locked planets are Eyeball planets (see here: <https://planetplanet.net/2014/10/07/real-life-sci-fi-world-2-the-hot-eyeball-planet/> and here: <http://nautil.us/blog/forget-earth_likewell-first-find-aliens-on-eyeball-planets>) There are some climate models for Proxima b that find Eyeball solutions. If the planet is covered in water, it will be frozen on the permanent nightside but with a liquid pond on the part of the planet pointing to the star. [![enter image description here](https://i.stack.imgur.com/4oxbK.gif)](https://i.stack.imgur.com/4oxbK.gif) This simulation is from this paper: <http://adsabs.harvard.edu/abs/2016arXiv160806827T> Note that there is also a chance that the planet is not rotating synchronously but instead in 3:2 spin-orbit resonance, like Mercury orbiting the Sun (see here: <http://adsabs.harvard.edu/abs/2016arXiv160806813R>). In that case there might be huge icecaps with liquid water along the equator. See here for explanation and a couple more animations:<http://nautil.us/blog/our-nearest-star-has-a-planet-and-these-are-the-ways-it-could-be-habitable> Or here in rhyme: <https://planetplanet.net/2016/08/24/the-eyeball-planet-next-door-a-proxima-poem/> [Answer] Genetic adaptations will always exist. And they will create unique adaptations to fit the situation presented. Once enzymes form microbial life on into plants, insects, and animals it will either through need to find nutrition sources or to escape being a nutrition source will adapt slowly but surely. Life forms will find a unique methods to cope with the extremes. As we see in our own planet life can modify to handle extremes from living at extreme pressures of the deep oceans, to the very high temperatures of volcanic steam vents to sub=zero cold of poles. 80% of our planets habitat is below 5C. Microbial life can not continue to grow and prosper below -15C. But mammals and birds can with adaptation survive even down below -50C (Emperor Penguin has been shown to live in winds chilled to this level). A microbe strain call Strain 121 actually has been show to survive at +121C. Sahara ants have been shown to be able to live in desert heat with body temperatures of +50C moving on the desert with ground temperatures of +70C ]
[Question] [ [In a previous question](https://worldbuilding.stackexchange.com/questions/47046/biological-explanation-of-age-stopping-in-near-human-aliens) I asked about a race that is extremely close to humans except for the fact that they physically and mentally (as in the acuity of the brain) stop aging somewhere between the ages of 25 and 35 (depending on environment and genetics, like human puberty). In the end they have roughly equivalent lifespans to humans. If we assume that we wave our hands and impose on this species a society much like the modern cultures of the first-world of Earth (non-specific, you may specify in your answer if you feel it's important to do so), how would this affect professions (and the professionals who fulfill these professions and their respective careers) in both the short term (<5 years), medium term (<25 years), and long term (<100 years). To clarify, these individuals stop aging. They are still capable of the same mental and emotional growth of humans but their body physically stops aging (including the brain). In short you wouldn't be able to tell the difference between a 25-35 year old and an 80 year old. Specifically, for point of comparison, focusing on the following professional groups: * High-skilled labor, such as doctors, lawyers, and researchers * Political professionals (governors, mayors, representatives) * Unskilled labor, such as factory workers or fast food servers * Military personnel To clarify, I'm not concerned with other effects (for example, we're hand-waving the social effects of suddenly there no longer being aged members within the society and the panic that might cause). The scope is exclusively the professions, their professionals, and the careers of the professionals, and how these topics might affect society. [Answer] One overarching thing to think about regardless of type of profession to think about in the first world is this: retirement. Most people don't exit the workforce because they are physically or mentally incapable of continuing, they do so because they have accumulated enough resources and eliminated debt such that they can live a more leisurely life. I imagine this effect might even be amplified in such a world, because the retirees would be "young" enough to travel, play sports, go skydiving, or do just about anything they fancy. They would have the youth and the money to enable a killer retirement. Highly Skilled Positions: A major factor is mental acuity. If an engineer or professor is just as alert at 80 as they were at 30, and they happened to be passionate enough about their profession to not want to retire, perhaps they would die doing what they loved. If not, these are typically the individuals (along with politicians) with the most money in the bank at retirement, which could make for a very luxurious and/or exciting last quarter of life. Political Professionals: Exciting retirement from above applies equally. Politicians can no longer accuse their opponents of being (mentally) old and senile. This might cause a stagnation of political power, as physical appearance plays a surprisingly important role in persuasion (and politics aren't about facts - they're about persuasion and emotional manipulation). I think attractive females would have a much larger pull in politics - both because they would remain perpetually appealing, and because the electorate of males would have the sexual drive and hormonal composition of a twenty-something. It's much easier to look the other way when the person doing wrong is a smokin' hot lady. (Source: I am a male twenty-something). Unskilled Labor: This will vary across different professions. For physically intensive jobs like construction or factory workers, consider that younger bodies are less prone to injury and heal more quickly. Physical strength won't diminish either, keeping workers in those positions much longer. I would label such jobs semi-skilled, though: it takes time to train someone in factory processes, and the like, which is some form of job security. It could spell doom for the totally unskilled workforce. The available workforce would be much larger across the board with unskilled labor, so that could mean a much quicker replacement if you screw up at your job. Like in our world (but maybe more so), it means lower pay because "anyone can do your job," except the supply of workers is now much higher than the demand. Military Personnel: First, it would mean that at no age do men (and women, if that's the way your society works) become ineligible for selective service (a.k.a. draft). Again, bodies heal faster and are less prone to injury, potentially extending soldiers' life expectancy. These effects work on both sides of the fight, though, so I could see wars of attrition lasting longer as more troops may be drafted and experienced troops survive better. [Answer] If there is no difference between a 25 year old and an 80 year old, then that 80 year old is capable of getting pregnant and having a baby. So instead of women who have to put their career on hold to have kids, then never quite catching up on the career ladder again, you could have women who have a high powered career and then retire at 60 to have their kids. (I'm assuming these are responsible people who don't have a kid at 80 because they know average life expectancy is 86. Though if there is no age related degeneration, then life expectancy may have leaped up to 96 or 106). High pressure professions may develop an ethos of 'career first, kids later', and not bother with funding maternity or paternity leave. Alternatively, perhaps people will not vote for a politician who spouts stuff about 'family values' but has decided not to have kids for another 30 years? If this tradition continues, these women will never see their grandchildren, because their own kids will also wait until they are 60 to produce them. I've deliberately not mentioned fathers, because Dad could be any age from a 16 to 80. After all, if all women look 25-35 then guys turning up their noses at older women will be on the basis of personality, looks ("I prefer blondes") or common interests ("You like jazz and Star Wars too?"). Meanwhile, your unskilled labour can spend 30 years flipping burgers and then still have plenty of time to decide to get an education, go to university and become a lawyer or researcher. Providing they've saved for their tuition fees, of course. But then, they've had 30 years to do that! And finally, enforced early retirement ages for professions like the police will vanish. [Answer] I am not certain that I have the answer you are looking for, but I do have an answer... As you will find throughout life, there are 'phases' i.e. the 'terrible twos, the rebellious teen, the party animal, the homemakers, etc etc. These predictable changes in life do not end just because one reaches any particular age, only death stops the changes. As found in Gail Sheehy's ["Passages"](http://rads.stackoverflow.com/amzn/click/0553271067) There are predictable, even inevitable crisis that follow every person in life. Our aging and maturation process produces biological change in us that is reflected in our personalities, our likes, dislikes and our interests. For most of your proposed people, these processes might be taken into stride, however for those 'professions' that require decades of study, or corporate ladder climbing, I propose that the lack of biochemical changes associated with aging would necessitate other mechanisms to allow for the evolution of personality throughout life. Just as an 80 year old man with Low Testosterone ( age related) will not exhibit the same behaviors as a 28 year old man, other changes would also be missed. [Answer] Ways to deal with this in the workforce. Long Apprenticeships high skill & politicos Since careers are longer, the time spent being a "junior" in the whatever field it is might be longer as well. This could apply to anything skilled. Peak and Diminished Pay high skill By law, once in a profession for a specific amount of time, the pay will peak, and then slowly drop off in value as they get past a certain age. I can see some folks talking up a new ident illegally and re-starting their careers, since no one can see how old they are. Term Limits politicos We have term limits for politicos. Elected officials only get to stay in office in a particular position for a limited amount of time. This has been a thing since, like, at least Middle Ages. I remember reading a book about life in the cities and elected officials (not Feudal Lords, of course) often rotated out. We age, and even we limit the amount of time someone spends in power. Military * Anyone can be drafted, once they are of age. The age might be older than the standard but, there aren't physical barriers. * However, age 35 is a time when many people are no longer as capable as they were when they were 20. The aging process has begun, even if it is stopped. I can see mandatory military service being a thing in this society. If anyone, at any age can get called up, you'd want them to be ready. * Also--and this is an interesting angle--maybe it's only oldsters that get called in. I mean, at 60 they've already had their lives so now--they get military duty, since there are not big physical problems with them serving. ]
[Question] [ One of the benefits of humanity is our subconscious need to explore. It is a simple instinct of primitive people wanting to know, not only what is in your territory, but almost what is around your territory. From this came greed, ambition and a bunch of other things humans have. But let's say, for some reason, humans were out of the picture. Assuming that I want a Neophobic species (like rats for a random example) to evolve sapience, what environment would best support this? Why would a species that, not only avoids, but fears new things evolve sapience. [Answer] # An "awakened" or successor species might pair dominant neophobia and sapience. Or, sapient species might cycle between neophobia and neophilia. Basically, a species that is designed from the ground up to to fear novelty while at the same time being capable of tricks like literacy could do it by hypothesis. A subservient species that grows into the spaces left behind by a fallen empire (dogs take over the planet as humans depart) might do it more "naturally". Here's a just-so story along these lines: humans grow more and more technologically advanced, and as we do we bring our pets along for the ride. Spot would be more fun if he could talk and scan the junk mail (with a child's intelligence, he'd love to do it!), and for that matter let's give that guy some thumbs so he can be player #2 in my video game, right? But as we progress, the standard of a child's (or childlike pet's) intelligence grows with us. Eventually humans could be massive coneheaded walking brains with dogs as bright as bright 20 year olds. Then somebody hits the wrong button on the gene resequencer and a retrovirus wipes out all humans. Whoops. So, the modified dogs take over, but their level of understanding is not nearly that of the coneheaded humans that left them behind, and experimentation and exploration are not particularly popular because that's not what they had been used for in human society for generations. They're mostly happy to stick around at home doing what they usually do (using the remaining technology that they had always been allowed to use), and when they don't, they pay for it. A first-to-flourish sapient species might be neophobic in some eras and neophilic in others, however, and I would argue that humanity is just such a species. Humans have not always been enchanted by exploration and discovery. There have been centuries when we barred ourselves from crossing the seas by drawing serpents at the edges of our maps. There have been centuries when witchcraft was punishable by burning, and any student of history or sufficiently poetic scientist will tell you that novel science counts as witchcraft. We're culturally tending strongly neophilic now because new things keep paying off. Every time a new thing shows up it's even better than the last one, a belief which seems doomed to exponential self-reinforcement by confirmation bias until we either become as gods or destroy ourselves. On that note, it's worth considering that an occasional neophobic cycle might serve an important role in the evaluation and adoption of technology. Our recent technological advancement has been very cool, to be certain, but we've sorta destroyed our planet, and maybe if we had arrested our development (even for the worst of reasons) for a couple of centuries in 1900, and really thought about whether we needed a billion cars or not... well, maybe the oceans wouldn't be in a death spiral. Or maybe they would be, but it'd be 200 years later! [Answer] Consider the following characteristics: Creature: * Extreme longevity * Little to no regenerative capabilities * Narrow variety of digestable food * Reproduces late in its life cycle Environment: * Creature's food sources are reliable and sedentary * Other organisms are potential lethal (toxic plants, defensive herbivores, etc.) --- Two things save us from our own creativity: our ability to learn from our mistakes, and our ability to recover from them. If you take away our ability to recover from accidents, we become much more cautious. Imagine a creature finds a fruit they have never encountered before. If the creature is like our own ancestors, they eat the fruit, get sick from it, but gradually recover over a short time. If eating that fruit was probably lethal, however, the creature would be much less inclined to try it. Similarly, exploring unfamiliar territory could lead to insect bites (or some equivalent), poisonous plants, or other environmental hazards. If these dangers were life threatening or debilitating and necessities were already close by, then a lack of curiosity would be evolutionarily favored. With these environmental characteristics, only those creatures that are extremely cautious survive long enough to reproduce. Now that the neophobia (cainophobia?) is out of the way, we're looking for intelligence. This can be easily explained with the hostile environment. The more intelligent the individual, the more likely they are to identify and avoid danger. Likewise, social functions develop in order to collectively combat these dangers. As with our own ancestors, those who could cultivate or domesticate their food would develop more complex social functions. [Answer] Basically I agree with @Kys; but will expand a bit: Intelligence (with or without sapience) is effectively the ability to learn predictive patterns. Whether they predict the future, or the unknown past. Although predicting the future (whether it is one second, one minute, or billions of years from now) is obviously useful, we can also use predictive patterns to understand the past: Sciences such as geology, astrology, forensic crime investigation, archaeology, paleontology, evolution; all of those use patterns to infer what must have happened. Most of those patterns extend into the future, but not all are predictive of the future: For example, evolution does not tell us anything specific about the future, just the generality that mutations will occur and may be adaptive and preserved. But the theory of evolution does not tell us if it is possible for any species with brains like ours to be smarter than humans. (Size may not matter and our most amazing prodigies may represent the peak of possible intelligence using neurons). Put another way, intelligence is learning predictive abstractions; or "models" of how natural forces (gravity, weather, etc) work, and how other animals will behave and react. These can be useful for survival and successful reproduction. Such learning does not demand consciousness or sapience; in my field AI techniques are very adept at learning such patterns and trading them in the stock market. But they aren't conscious or sapient, they have no sense of self. On this theory, sapience emerges when the patterns learned end up being complex enough to demand a predictive abstraction of yourself as an actor in the outcomes. As an actor in the model, the prediction becomes an "imagination", imagining the outcomes of our own actions is an exercise of such a model, and leads to planning and intentional manipulation of the environment and others. (In fact, we call people with poor models of themselves, and imaginations that are poor at predicting what will happen or the consequences of their actions, "dumb.") Consciousness does not require any language; it is just the constant cycling of this predictive models of yourself as an agent, first, and others and the environment and situations, to determine what you will or should do next to accomplish some goal or desire. Using this as the model of distinguishing between "intelligence" and "sapience / consciousness", we can answer the question: The species does not need to explore, but it does need a high motivation to survive and reproduce. To develop sentience, it needs to (like humans) be weak against predators so it cannot rely on speed, claws, camouflage or any natural physical advantage at all, it must on slightly higher intelligence than the predators that lets it predict how they will behave so it can avoid being ambushed, or poisoned (snakes, insects, spiders), or chased down. Or develop unnatural tools (spears, nets, deadfalls, spike pits) to give them a chance against their attackers. pre-Humans were prey at one point, frequently. We were not always hunters. So you just need a strong evolutionary pressure to make better predictive models a survival advantage, particularly for a weak species that has nothing else. Neophobia is not an issue, being physically afraid of the new is fine, but does not prevent one from developing an abstract predictive model of the new thing (aka "understanding it"). In fact, if there is pressure to expand one's territory, for more space and food for the kids, better models will help do that: So loving a big family can suffice: They don't like the new, but they need the space, they need the safety ("safety" is itself a prediction of the future), they need the food. In humans it is hypothesized that once we used intelligence to conquer most physical threats, it was our social environment (other humans) that created a feedback loop of higher intelligence to understand other humans, and out-do them for resources needed for survival and reproduction. So every advancement in our ability to understand affords a reproductive advantage, but becomes the standard 'floor' within a dozen generations or so, until another mutational advancement comes along, which then becomes the new standard 'floor', etc. Which may lead to our current state of very high intelligence, compared to other animals, but for most people still barely enough to hold their own against other humans: We are our own biggest competitors. So a similar thing could happen for a fictional species, small advances in intelligence first afford them survival in a hostile world, but once that world is mostly tamed and controlled, even better predictive models are needed for them to compete against each other for their reproductive resources. [Answer] I suppose they might fear the unknown because they are a herbivore species and us such are prey to many predators living around them. I would also propose that they are cave/underground dwelling creatures, since (at least as far as I know) there are no predators who live underground (on Earth). Hope it helps at least a little bit. ]
[Question] [ I'm designing a mission to a planet orbiting 61 Virginis (27.9 ly distant), and want to stay within physics that we're aware of (e.g. no warp drive). I've asked questions [here](https://worldbuilding.stackexchange.com/questions/39201/laser-boosted-solar-sails-to-61-virginis) and [here](https://worldbuilding.stackexchange.com/questions/39210/61-virginis-mission-design-ship-mass), and the answers to those tell me that it's a tall order. For one, getting up to a reasonable fraction of the speed of light in a reasonable period of time seems to require accelerations that would be unreasonable to the human body. So, my question: if I'm going to have my passengers in cold storage of some sort, but not so cold that they've gone solid (no "carbonite", but deep sleep and slowed biology), what sort of acceleration can I use? I'd like the trip to be in as short an amount of time as possible for story continuity, so multi-thousand year transit won't work. Ideally they'd get there in less than sixty or so years, but a couple hundred years would be OK. Is it feasible? [Answer] One thing we have to take into account is that you can only accelerate for the first half of the trip. You then have to decelerate for the second half; otherwise, you won't be able to stop unless you crash into your target! So the proper time observed by someone onboard a ship for the first half of the journey, $\tau\_1$, is during a period of acceleration for the first 13.95 light-years. The total proper time, therefore, is $\tau=2\tau\_1$. [This report](http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930020462.pdf) states that humans can survive an acceleration of two to three times the acceleration due to Earth's gravity for about 24 hours without adverse effects. Let's see what would happen if we were to send our intrepid explorers off at this acceleration. [This comprehensive answer by John Rennie](https://physics.stackexchange.com/a/109777/56299) gives a formula we can use for $\tau\_1$ and $x\_1$: $$x\_1=\frac{c^2}{a}\left(\cosh\left(\frac{a\tau\_1}{c}\right)–1\right)\tag{1a}$$ We can then rearrange this to solve for $\tau\_1$: $$\tau\_1=\frac{c}{a}\text{arcosh}\left(\frac{x\_1a}{c^2}+1\right)\tag{1b}$$ Plugging these values into my calculator, for $\tau=2g$, I get $\tau=2\tau\_1=2.96$ years. If we cut the acceleration in half, to the much safer $g$ we feel on Earth, this brings the proper time to about 6.65 years - again, well within your time frame. John Rennie added a couple graphs into his answer, so I feel compelled to do the same. Here is the graph of $\tau(x)$, assuming an $x\_1$ of about 13.95 light-years and a total travel distance of 27.9 light-years: [![graphs of time measured by traveler in years per distance traveled in light years for the values 0.25g, 0.5g, 1g and 2g with a vertical line depicting the 27.9 light years from the original question](https://i.stack.imgur.com/U7Oqd.png)](https://i.stack.imgur.com/U7Oqd.png) [Answer] Unless you are planning to shoot the passengers out of a railgun, then there really isn't an issue at all. Without getting into a lot of heavy duty math, accelerating at a constant 1\g\ for a year will bring you to a very high fraction of c (in fact you will have traveled half a light year and be moving at just under the speed of light). Then you can coast towards your target and at the appropriate time start to decelerate. Marshal Savage, in his book "The Millenial Project" suggested that in the far future instead of starships, there would be mass drivers that span the length of the solar system and accelerate pods to high fractions of c, and corresponding mass drivers at the target star systems to capture and decelerate the pods. In his conception, the launch tube is 3000 AU in length, and the pod inside travels at 10 g for a month to reach 99.99 c. Obviously that is far beyond what a normal human could withstand (trained fighter pilots in g suits handle accelerations of up to 9 g for short periods of time), but if the person is suspended in some sort of fluid filled capsule and all their internal spaces are filled with an oxygenated fluid then they will be far less affected. So these probably represent the two extreme ends of the spectrum for travel at near luminal velocities. Naturally, moving at this speed requires massive amounts of energy to accelerate or decelerate (Robert L Forward's laser driven light sail needs 70,000TW of laser energy to accelerate to a modest .5\c\), and you would also need some pretty impressive shielding to protect the cargo and crew from impacts with even molecules of interstellar gas. ]
[Question] [ Let's say I happen to find myself outside of earth's atmosphere [right at the Kármán line 100km up] one night and don't wish to cause a fuss as I descend to my home. I am stationary in regards to the dirt beneath me. Could I inflate a transparent non-reflective balloon of sufficient size say 1 million $m^3$ with hydrogen and descend into the atmosphere without glowing or causing a sonic boom, landing in my backyard using my impeccable ballooning technique? Releasing gas as needed. [Answer] You'd be better off simply using a parachute. You're not in orbit, you're just very high up, [there is a big difference](https://what-if.xkcd.com/58/). [![enter image description here](https://i.stack.imgur.com/Uzl9H.png)](https://i.stack.imgur.com/Uzl9H.png) Because of this, you're not going fast enough, [nor will you get going fast enough](https://en.wikipedia.org/wiki/Space_diving#Challenges_to_safe_space_diving), to burn up while you're falling. The highest skydive thus far was done by [Alan Eustace](https://en.wikipedia.org/wiki/Alan_Eustace) in 2014. He detached from a balloon at over 41 km up and after falling for a rather long time, he opened his fairly standard parachute. As @2012rcampion calculated in the comments, you'll probably want to use a drogue, just like Alan did for his jump. These are commonly used for tandem parachutists for stability and slightly increased drag; they're not hard to come by. If you're an experienced parachutist, you can make some pretty tricky landings in very small spaces. You won't need to worry about bringing along all that lifting gas and a massive balloon. Just a regular parachute. As for the stealthiness of the entry, this is the entire goal of [HALO](https://en.wikipedia.org/wiki/High-altitude_military_parachuting) jumps. You might call yours a VHALO (Very High Altitude, Low Opening) jump. Using similar techniques, you can make an incredibly stealthy entry into your home country. As stealthy as military research can make you. > > In a typical HALO exercise, the parachutist will jump from the aircraft, free-fall for a period of time at terminal velocity, and open their parachute at a low altitude. The combination of high downward speed, minimal forward airspeed, and the use of only small amounts of metal helps to defeat radar and reduces the amount of time a parachute might be visible to ground observers, enabling a stealthy insertion. > > > [Answer] Samuel has covered this pretty well, a stealth re-entry is just fine since you're not in orbit. It is the orbital speed of many many thousands of mph that causes most of the problems when re-entering the atmosphere. The main problem you will have is that there is no atmosphere to slow you down for the initial parts of the fall, this means that you will not have any terminal velocity to speak of. Fortunately the atmospheric pressure is increasing gradually so use of a correctly sized small parachute should allow you to decelerate as the atmosphere thickens, what you don't want to do is hit the atmosphere at supersonic speeds and start overheating and/or creating sonic booms. Once you've reached the atmosphere proper ditch the drogue and do a standard free-fall to HALO insertion to reach your target in a manor as stealthy as your parachutes will allow. [Answer] If you're descending from Earth orbit at say, 17,000 mph, your large balloon (assuming it can take the reentry forces) is still going to heat up the atmosphere into a fiery plasma as it trades velocity for heat, and it's still going to go 'BOOM' because it's travelling faster than sound. It might be a sharper 'BOOM' rather than a 'BABOOM' that a more conventional reentry vehicle would make. If you want to make a quiet reentry, you need to slow down to below the speed of sound before entering the atmosphere. Then you can make a nice quiet landing, maybe slipping into a general aviation flight pattern. You'll need extra long skirts on your rocket exhausts, to mask the flare of the engine. ]
[Question] [ I'm making a world with magic and most if not all tech will run on mana. I have airships in this world but I'm having a hard time deciding how large across the world should be. I want - even with airships - for long distance travel to take months (cross a continent or from one continent to another). Should I set a slower airspeed than airplanes now, and have the world the same size as Earth, or increase the size of the world, or both? [Answer] Using [LZ 127 Graf Zepplin](https://en.wikipedia.org/wiki/LZ_127_Graf_Zeppelin) as an example of a transatlantic airship flight from 1928, it took 111 hours to travel from Friedrichshafen, Tübingen, Germany to Lakehurst, New Jersey, United States of America, about 9,926km in length. Faster: In a similar airship that is capable of achieving the same speed of 89km/hr, on a similar journey across a Continental divide, the distance would need to be 150,000km to achieve a two month journey taking 10 weeks. This means your theoretical planet would need to be on a scale of 15x the size of the Earth to achieve a similar journey over a longer time. This massive world would probably increase the likely-hood of transition to air-travel as the speed to cross long distances would be a must for world spanning empires. Slower: If you wish for your airship to just travel slower to make the journey longer, to achieve a 2 month long journey taking 10 weeks,you would need to slow your airship to travel 6km/h to travel roughly 10,000km across an earth sized ocean. In terms of world building, the slower option makes less sense as most people can walk faster than 6km/hr, and any naval vessel could easily outspeed this airship. Unless of course the ocean in your world is so acidic that the only way to traverse it is to fly above it! Between: Below is a quick table of some compromises between the above suggestions: ``` \| Distance \| Scale \| Speed \| Likeness to other modes of travel\| \| 150,000km \| 15x \| 90km/h \| Speed of Car \| \| 100,000km \| 10x \| 60km/h \| Speed of Early Model Steam Train \| \| 50,000km \| 5x \| 30km/h \| Speed of Horse Gallop \| \| 20,000km \| 2x \| 12km/h \| Speed of Runner \| \| 10,000km \| 1x \| 6km/h \| Speed of Fast Walker \| ``` [Answer] Basing this off of JustAnotherDotNetDev's calculations: The big problem with making the planet much larger is of course gravity. As Michael pointed out in the comments, Jupiter is 11x the radius of earth, is mostly hydrogen and we wouldn't survive for very long under the huge crushing weight of our own bodies. So find reasons to slow things down. The one thing I can see that might help slow things down is that the people only navigate visually. so when the sun goes down they try to find a place to 'anchor' for the night. This would mostly double the time it takes to fly anywhere, and it would still be significantly faster than walking. One more thing might be that large merchant ships and large troop transports are large enough to just wallow along at 100-200 feet above the ground, and they might need to partially empty to navigate mountain passes, slowing things down more. Really high passes might need to actually completely empty the ship and 'carry' it over the pass to the other side, this could take weeks all by itself, and make the seasons have a huge impact on long distance travel. [Answer] Since all the tech (including the airship engines I assume) runs on mana, then in addition to bowlturners ideas, you could limit speed by the need to "refuel". I'll have to make a few assumptions since you didn't specify how mana works, but if mana isn't a constant, unlimited resource, then it'll have to be replentished. So the airship could be able to travel at 89km/hr, but only be able to travel for 6 hours before having to stop and recharge for a few hours. This could limit the ship to 1000km a day. Less if the engines aren't as efficient. Add to that high mountain ranges that need to be navigated around so straight line travel is impossible. So a straight "as the crow flies" distance of 10,000km could end up being 30,000km of distance needed to travel. Another thing that could slow it down is scheduled stops. Say the world is heavily forested, and mountainous, so ground travel is difficult. You still have settlements and towns that need supplies and people that want to move around. The airships are the obvious choice for this, meaning that airships would have routes and have to make stops at each location along the way. Docking, unloading, and loading could take a while depending on what's being moved around. This would slow down the travel time too. You could still have express airships that only make a few stops. One other thing would be weather. Airships have trouble in high winds, so if your world has frequent storms, or even something like the [Santa Ana Winds](https://en.wikipedia.org/wiki/Santa_Ana_winds) or [Chinook winds](https://en.wikipedia.org/wiki/Chinook_wind) where the wind will blow hard for days/weeks at a time. The airships would have to anchor and wait for things to die down. Either that or travel really slowly, fighting the wind the whole way, and making frequent stops. Edit Another weather issue could be fog or low clouds full of things like tall trees and rocks. It could even be kind of like river navigation, where you had to have a navigator that knew where all the sand banks were in order not to run-aground. If this happened frequently, they would be forced to travel very slowly or risk crashing until the clouds lifted. [Answer] You can increase the radius/mass of the planet, as well as the density of the atmosphere. The bigger the radius, the bigger the circumference, and thus the further apart places will be. The bigger the mass, the higher the gravity thus you need more lift per pound to fly. The denser the atmosphere the more drag you'll get. Denser atmosphere provides more lift, but the higher gravity easily makes up for that. At the end you end up with slower airships (due to the higher gravity you'll have weight restriction, won't be able to carry enough fuel etc), more drag and greater distances to travel. On top of that add finicky airships that require ground service every few days and inability to navigate at night most nights and it could easily take months to go transcontinental. ]
[Question] [ Let us consider a medieval word without magic (there are castles, knights, kings, blacksmithing, sail ships, monotheistic faith) very close to ours. On one unlucky day the borderland deserts are crossed by unfriendly nomads (like medieval Mongols). These nomads raid cities and wreak havoc. The most terrifying part about them is they are carriers of some deadly disease like [Typhoid Mary](https://en.wikipedia.org/wiki/Typhoid_Mary). They have this disease, and they do not suffer from it, and everyone else - yes, even the breath or blood of a nomad can spread contagion. So, the question is: what can this disease be and how can this wicked protection of nomads be possible? I leave my thoughts here;, I'll be grateful for your ideas and help. Hint 1: The nomads' immunity can be result of generations of natural selections, and the real carriers of the disease can be, for example, fleas. They live near nomads for generations, and only the immune one nomads survived. Hint 2: The shamans of nomads knows the secret cure, and they distribute it among their kin along with the meat of diseased animals. [Answer] This has happened many times. measles, mumps, smallpox, influenza all have had populations where the carriers are mostly immune to strands and when they meet with 'virgin' populations, they decimate them. It is believed that a large % of the Native American population was wiped out by diseases from Europe before Europeans ever set foot on many lands. Small pox wiped out huge swaths of the Americas. So it isn't that hard to envision a some disease being hosted in a body that has adapted to it while spreading quickly to those who were never exposed. ]
[Question] [ Let's say there's an OCEAN planet smaller than Earth but larger than the Moon. The Sun lights on the ocean planet reflecting the water textures onto Earth. Would it be possible to see watery reflections on Earth during night? If not... do you have any idea how to achieve similar result? I'm talking about this kind of reflections. ![enter image description here](https://i.stack.imgur.com/Im0v6.jpg) ![enter image description here](https://i.stack.imgur.com/lrOw7.jpg) [Answer] # NO Let's reverse the scenario for a second, and talk about reflections from the Earth onto the Moon. The Earth is not 100% water, and is partially covered by clouds, but since it's a lot bigger than your watery planet the visible water area is similar on average. Plus, the Moon makes a much better "canvas" for any possible reflections since its surface is far more uniform than the Earth's. Can we see any reflections on the Moon? ![enter image description here](https://i.stack.imgur.com/foUYj.jpg) Well, maybe the moon is just too far away and the earthshine too dim. What if we get really close to the oceans... like [400 km](http://www.wolframalpha.com/input/?i=iss+altitude) close? ![enter image description here](https://i.stack.imgur.com/hST3M.jpg) Note that, in this picture, we're looking at the nadir (Earth-facing side) of the ISS (you can tell from the [Leonardo module](https://en.wikipedia.org/wiki/Leonardo_(ISS_module)) sticking out the bottom) and that the sunlight is coming from the top of the screen (see the shadow of the Orbiter's wing on the starboard solar array). This means that the scene is partially lit by earthshine; in particular the underside of the radiators is completely lit by reflected sunlight. No patterns are visible. # Why? The pattern of light you're looking for is a type of [caustic](https://en.wikipedia.org/wiki/Caustic_(optics)). Caustics are caused when reflection or refraction off of a curved surface causes light to be concentrated at some points and diffused at others. You can think of each wave in the surface of the water as a poor approximation to a lens, focusing the light that it refracts or reflects. The kicker is that the approximate focus point is relatively close to the surface. Take a look at this computer rendering: ![enter image description here](https://i.stack.imgur.com/duaTi.png) As you get further and further from the surface, the refracted light becomes defocused and the patterns start to blur together. The distance at which the caustics totally disappear is one or two orders of magnitude larger than the wave dimensions. So even under ideal circumstances, a planet with 10 m waves couldn't have caustics visible at 1 km or more, much less the hundred thousand or million kilometers to another heavenly body. [Answer] It's almost completely impossible Those textures occur because of the waves on a surface. Each reflect light in a slightly different direction. Where many patches of water reflect, the effect is bright. Where few patches reflect, it is dim. However, this effect fades over distance. Near the water, you get most of your light from water nearby. The r^2 losses from distance make the lighting effects from further away patches dimmer. This means the lightness or darkness is based on the variation in angle of a very small region of water. At greater distances, the difference in brightness from near patches and far patches is much less. Thus your effects are averaged out over a larger patch of water. At planetary distances, you would get a completely blurred light source. The planet may shimmer like a star, but you will be hard pressed to have visibly different effects in Moscow vs. Tokyo. The angles are just too close and the effect is too blurred. To get this effect you would have to get the planet to actively cast a light pattern directly at the earth, rather than relying on accidental effects. You would need the ocean planet to take on holographic properties, ensuring all light that hits the ocean is columned properly to generate the desired effects. You could do it with complete planetary control... but at some point it would be easier to achieve the effect with a large array of holographic gratings. ]
[Question] [ In a story I'm about to start, magic is an inherited ability to manipulate energy and matter. Mages use mage sight to see elements, compounds etc. as different colours and energy as distortions, then manipulate them to 'cast spells'- but they don't have to understand the physics, chemistry or biology to do so, they just know how to do it(they know how to use oxygen and energy to create fire, how to use water in the air as ice-blades by turning heat energy to light+kinetic, that kind of stuff). In this setting-with all laws of physics- how would shapeshifting work? In my head, all mages need a dna 'scan' from several species and have three distinct alternate forms-aquatic,aerial and terrestrial- while Druids(one of many variants, like mindreader or illusionist) can add more, with greater variance(amphibious, half human, that kinda stuff) [Answer] You've stated that these mages are able to edit energy; if so, why not use that skill to shapeshift? The mages could just warp and bend light around themselves, which would make it appear that they have changed shape (like looking into a curved mirror, or through an oddly shaped lens.) And, to change colors and such, all the mages have to do is change the wavelength of the light around them to get the desired color. This isn't proper shapeshifting, as their actual shape doesn't change, but it would certainly appear that way to any onlooker. Based on another answer, [and my comment there](https://worldbuilding.stackexchange.com/questions/15179/shapeshifting-and-scientific-magic/#comment-37156), true shape-shifting would be encumbered by [conservation of mass](https://en.wikipedia.org/wiki/Conservation_of_mass). That is, when transforming into a mouse, what happens to the leftover mass? A mouse is much smaller than a person. Well, what could happen is that the mage uses their energy manipulation powers to convert any [matter into energy](https://en.wikipedia.org/wiki/Conservation_of_mass#Matter_is_not_perfectly_conserved), thus changing their actual mass. This would mean that, when changing into a mouse, the surroundings would be superheated, or a lot of light would be produced, and when changing into something bigger, like a bear, the environment is supercooled, because the mage is absorbing a lot of energy (most ambient energy is heat) to convert back to matter. I think that that would be pretty cool, because shapeshifting could inadvertently freeze an ocean, or burn down a forest! Or, another, less exciting route would be to just shed the expended mass as another, gaseous compound: you've stated that your mages have power over compounds as well. [Answer] Conserving mass is going to be a slight problem, if you want to keep it somewhat science based. Think of the size difference between a man and a rat. 180lb vs 2lb. Where does the extra mass go? Does he just become a really big rat? That might be a way to solve it. All creatures have basically the same organs, with a few differences here and there, but those differences aren't obvious without an autopsy. So if he becomes a cat, it has to be a big cat. If he becomes a bear, it has to be a small bear. I think the best thing to do to avoid problems is to not explain how it works. It's good for you too have an idea of how it works so it stays consistent, but you're readers don't need to know how, just that it does. > > [Sanderson’s First Law of Magics:](http://brandonsanderson.com/sandersons-first-law/) An author’s ability to solve conflict with magic is DIRECTLY PROPORTIONAL to how well the reader understands said magic. > > > [Answer] I think there are many problems you would have to solve with shape-shifting. However, nature has a way to do it already mapped out. If you look at the life cycle of a butterfly. It is your realistic path to a process you can use to mimic, how it’s done. They start off as eggs that turn into caterpillars. Then they will create a chrysalis and inside the shell their body will liquefy and change into a butterfly. I have ideas on how the magic could be applied to deal with many details of the process. However, it is quite a great place to start. Lol great question, I am going to have to steal it for my podcast. Thanks  [cycle of a butterfly](http://www3.canisius.edu/~grandem/butterflylifecycle/The_Lifecycle_of_a_Butterfly_print.html) [Answer] Maybe take advantage of their ability over matter, to give them some control over their own matter - including the ability to adopt or abandon mass. Most flesh-and-blood beings are made of mostly the same sorts of things (on the level of compounds and elements, anyway). So if your mage can rearrange them, they can easily make a crude shift into those beings of roughly the same mass. The better they know the beings, obviously, the better the final form looks, moves, and feels. Maybe give a couple of cheats - like if they shift into something while actively using mage sight to analyze it - and DNA makes sense because it is a blueprint - the copy is pretty good even if they've never been it before... but if they don't have a copy, they better have a pretty good memory to make the form work right, because incorrect anatomy can really mess things up. Maybe your 'three types' of beings are something from basic education - every kid is taught to have several sets of DNA memorized, in case they can't find anything nearby to copy. So a young or inexperienced shifter would have to be a really specific copy ("this" cat, down to DNA), while advanced shifters who have a lot of experience in how bodies move and work, can be a more generic example (cats are kinda like this), can remember more forms, or can try more extreme modifications like between shapes without crippling themselves. So that takes care of things nearly the same mass, so what about things of different mass? Well, they can control matter and control themselves, so let them add or abandon mass to make it work. Maybe it's hard, or painful, or tricky and takes lots of skill so only advanced shifters do so, depending on how available you want the ability to be. There has to be a (probably subconscious) mechanism for adding mass to a mage's control, or removing it from control, or recently eaten food wouldn't get transformed (messy). A small difference might work by converting energy, but for larger amounts - borrow mass from a nearby tree or rocks, or drop off extra as a pile of bones or for a big discrepancy just transform part of the body and leave the rest behind vulnerable... with or without consequences if they don't lose or reacquire that mass after a while. Maybe if they're shifting into something that does have a significantly different makeup, it's better if they acquire whatever compounds or elements they're missing - whether its more calcium so their new bones are strong enough, or trace elements to make the critter's venom work. Maybe with enough practice they could edge into forms that are really different, like seemingly-inanimate objects. Depends on how far you want to take it. [Answer] Making fire and ice are pretty much just telekinesis and energy transfer, indeed I imagine telekinesis could be used to redistribute thermal energy with a kind of Laplace's demon sorting mechanism. But the complexity of rearranging molecules from one complex arrangement into another (e.g. an uncut diamond into a prism) would be hard enough let alone the transmutation required to turn one creature into another, and that's assuming you're exchanging mass with the surrounding environment. By sheer complexity I think shape changing would have to be a subconscious process, also there's the Star Trek teleported issue to contend with, if a bunny bursts out of a mage's chest (he didn't need all that mass) couldn't said mage just as easily turn himself into a bunny while leaving the original (possibly lacking a few kilos of fat and muscle tissue) intact? [Answer] Maybe your mages can have unique birth marks. Then each of your mages with the three distinct alternate forms-aquatic, aerial, and terrestrial can split like a "zygote" into a pack of identical fishes, birds, or mice each bearing part of the unique birth mark of the original mage. To reverse the effect their smaller identical forms with parts of the unique birth mark fuse back to the mage's original form with his or her unique birth mark. For example a pack of birds with parts of the unique birth mark fuse back to the aerial mage's original form with his or her unique birth mark. For creating larger forms like an orca whale, a dragon, or a bear, the "alike" mages fuse their bodies together. For example several aquatic mages fuse their bodies to form an orca whale bearing markings that are all of their birth marks. To reverse the effect they split apart to return to each of their original forms with single unique birth marks. The druids were formed when mages of two different alternate forms mate and reproduce. For example an aquatic mage mates with a terrestrial mage to produce the amphibious druid with the new trait of mindreading. ]
[Question] [ I am envisioning a world around a red dwarf star. The planet has violent and accelerated (due to higher geological activity) plate tectonics and has a magnetic field about 75% the strength of the Earth's. The planet (we'll call it GF10) is roughly 40% the size of the Earth. The planet used to be nearly entirely covered by oceans but they eventually evaporated. The planet had a relatively flat surface and 80% of that surface was covered by 20% of the water found on Earth. Most of said water evaporated, making a dense atmosphere that traps heat. There is only a sea the size of South Africa running horizontally along the planetary equator. The planet has two moons roughly the size of Phobos. Orbiting the planet elliptically. The planet is gravitationally locked and orbits widely. During the summer weeks it is in the habitable zone, but its orbit takes it dangerously close to a gas giant (as well as to the edge of the habitable zone) to the point that it is viewable from the surface. My question is this: How might animal life (assuming life can be relatively easily divided into animal/plant categories) evolve to live on such a world? I might not have described the orbit correctly so here is a map. Map of orbit (not drawn to scale): ![enter image description here](https://i.stack.imgur.com/DbOJn.jpg) [Answer] Since a Red Dwarf is a very dim star, any planet in the habitable zone will be quite close and tidally locked to the primary. The planet will have multiple ecosystem bands based on illumination, with the "hot pole" having the primary directly overhead all the way to the "cold pole" on the opposite side of the planet. Atmospheric circulation will be fairly intense, with a permanent low pressure cell based on the hot pole and a high pressure cell at the cold pole. Since the planet does not rotate, there is no Coriolis effect to deflect the winds. Animal life will be adapted to living in a low light environment, probably with high winds near ground level rushing towards the hot pole and equally high winds in the upper atmosphere rushing towards the cold pole. There are no day/night cycles like we have, so the creatures will probably not evolve anything like a circadian rhythm. They may end up with a brain structure similar to a dolphin, being able to "go to sleep" with one half of the brain at a time so they do not become vulnerable to predation or natural disaster. Living in a permanent twilight, they may develop large eyes, but other forms of sensory apparatus like electrical fields, echolocation or even blind creatures using smell and touch can all be envisioned (there are probably ecological niches for every kind of creature). Flying will be very challenging, since being caught in the wind with no viable means of directing your path means being swept towards the hot or cold poles, and likely being swept out of your own ecological "band". If the winds are strong enough, the ecosystem might resemble a corral reef, with creatures anchored to the ground and extending tendrils into the air to snag pollen, sperm from male creatures or edible matter (even dust carrying minerals might be important for their metabolism. Most of these assumptions assume a similar biochemistry to that of Earth, but adapted to more extreme conditions. [Answer] Most likely, if animal life would exists on Terra-like planets orbiting red dwarfs, they would need protection from the frequent solar flares of their red sun. To evolve, they would require protective shells. For mammals, possibly a tough layer of dead skin. They would crawl in caves or hide in the mud until the sky clears itself. The animals who couldn't find adequate shelter or lose theirs at the expense of others would be ''cooked'' and then devoured by the surviving predators after the flares would be gone. Instead of seeing the blue reflection of the oceans, the sky would be transparent due to infra red light. The vegetation would appear in shades of dark green or even black. Just guessing, but it's fun Richard ]
[Question] [ I'm researching a bit for book idea and would like some input. Say I'm a dictator that would like to use rationalist dogma as a front to unify my country. Obviously, it wouldn't be using pure rationalism, but prima facie, my basic tenets would resemble rationalism. How could I distort a rationalist ideology to best control my constituency? And what fallacies would this distortion be the result of? [Answer] The best way to distort a logical, rational argument in such a way that it's difficult to refute is to change axioms, or to use invalid axioms. For example, the following statement is entirely logical: > > Pigs are birds. Birds can fly. Therefore, pigs can fly. > > > So the logic is sound - if pigs are birds, and birds can fly, then of course pigs can fly. The reason the conclusion is wrong is because one of your axioms - pigs are birds - is false, and that invalidates your final conclusion. So what your dictator needs to do is find an axiom that appeals to the people of his country, that they want to be true, and that's not easy to refute. Emotional appeals work well here. He can then use this as the basis for rational/logical arguments to assume power. Attempts at going against the axiom will run into the emotional support, and it's not possible to invalidate the logic directly. You have a few possibilities here for your false axioms. A shared enemy (another country, or a minority) is a common one - humans seem to be hardwired for "us vs them", so creating an outside, [dehumanized](http://en.wikipedia.org/wiki/Dehumanization) enemy can be the basis behind your actions. [Answer] Most important, remember one thing: emotion is faster than rational thought. Fear is the fastest. For millions of years, this had evolutionary advantage. So load your propaganda with emotions, mostly fear of "others". Then, easiest way would be to rationalize why your nationality is supreme over all others. Even better than invalid axioms, would work plausible, believable lies. Then you pull few well-proven tricks from nazi propaganda machine: * Start with complete control over mass information system, and education. You want people who have no idea how much they do not know. * then, if you repeat lie 1000 times, people start believe it - [Goebbels](http://en.wikiquote.org/wiki/Joseph_Goebbels) * Some lies have wild popularity: [If you are not with us, you are against us](http://en.wikipedia.org/wiki/You%27re_either_with_us,_or_against_us) - Used by Lenin, Mussolini, and surprisingly for Europeans, GW Bush * Convenient enemy who is at fault if anything goes wrong. Better if it is close-by: some of your neighbor nations. To fight such permanent enemy, you of course need temporarily restrict freedom of speech and enforce censorship. And anyone who disagrees about restriction is not patriotic enough and suspicious - [McCarthyism](http://en.wikipedia.org/wiki/McCarthyism). * Most people will torture others to obey authority, as proven by [Milgram experiment](http://en.wikipedia.org/wiki/Milgram_experiment) Works like charm. Most people want to join someone who looks like a winner. read [1984](http://en.wikipedia.org/wiki/Nineteen_Eighty-Four) if you haven't yet. For people who grew up in such situation, decision to support you seems to be completely rational. ]
[Question] [ I'm writing a story (not sure if it's speculative fiction or low fantasy or sci-fi) that is set in a fairly realistic world except that there is a parallel dimension which humans colonized in what would be the real world's equivalent of the classical era. Portals between the worlds are naturally occurring, opening up at predictable intervals every 2 decades or so and remaining open for about half a year. With the advent of electricity, opening smaller man-made portals became possible, as well as allowing interdimensional communication. The problem is I also have an equivalent of the Americas, which I combined into a single continent a little larger than Africa. The actual story is set in this world's equivalent of the 1930s-1940s but the parallel dimension wasn't colonized until after the Americas would become populated, leaving their parallel universe counterpart completely uninhabited. The main focus of the story is actually geopolitical with a great war similar to WW2 and elements of the cold war taking a center stage, but I just realized that the existence of a whole continent that is completely uninhabited would probably have drastic effects on colonization and all of history and I am trying to figure out how to address this without absolutely destroying the rest of my worldbuilding or being forced to scrap most of what I have so far. [Answer] In short: Too many downsides, not enough upsides and then add in a pinch of No one bothered to record it What do I mean by that: Well, there are many places on earth that are sparsely populated by humans - Deserts, Antarctica etc. The lack of resources and little in the way of benefits could adequately explain this situation. Colonization is a costly process and those who partook in it were expecting to gain something: * People/Slaves for workers/exploitation. If there are barely any people there, then this rules that out. * Strategic/tactical considerations. Otherwise unimportant areas can be critical if they provide some tactical benefit - Gibraltar for example to the British or the Pacific Islands (and Cargo Cults) for the US in WW2 - On the inverse - New Zealand has literally zero in the way of Strategic benefit, which is why it's often forgotten about. * Resources - To quote Al Murray 'If there's nothing in the way of Hot and Spicy food or olympic quality athletes, there's no point going' - So make your continent at least on an initial inspection to be devoid of anything useful (bonus points here for your story if it is rich in something which later on has significant usefulness) * Arable Land and tasty wildlife - You could put this as similar to Resources - but the ability to easily grow crops or hunt game is slightly different - this is perhaps the biggest inhibitor to further exploration, there's only so much food and water you can carry with you - a reasonable 'limit' is 10 days worth of food for walking exploration. In the short-term this will provide a significant disincentive to push further but in the grander scheme of things it will limit further exploration and finally * Lack of navigable waterways. Thomas Sowell discusses this in regards to Africa as to why African civilizations didn't 'succeed' in the way that other civilizations did (European, Chinese, Japanese etc.) and he points to the lack of rivers where goods can be ferried in bulk as one of the factors as this limits trade and slows down the transfer of materials. Finally - If you all of those are met (and I think it can be reasonable to do so, with the right settings) - you could have a continent that is largely left alone - add in that people who did 'discover' it found nothing of interest sufficient to warrant further exploration would solve your issue. [Answer] Just make the new American continent really, really deadly. It can't be colonized by rogue individuals, *everything* is poisonous. The creatures, the soil, the insects. And vice versa, they cannot survive in the "Normal" World. IN fact, that is why the Europeans in the Alternate world haven't colonized it, explorers do not return from this continent. In the Americas, isolated, evolution resulted in an "arms race" for poisons; instead of muscles, fangs and claws, they developed toxins, immunity, then stronger toxins to overcome immunity. Animals there do not consume by eating, like a few creatures on earth they dissolvetheir prey with acids, and swallow the "soup". People can't survive there, the only way to colonize it is a massive effort to protect themselves from the toxic life there, build shelters to keep out everything, fry the soil to sterilize it, and all the insects, creatures and plants in it, and then start from scratch with "Normal" world plants and animals. And strong water purifiers. All that would take decades to build a self-sustaining colony. It's just not worth the trouble, either for the Europeans already there, or the Americans in the Normal world, unless there is a very compelling reason to leave the Normal America and go to the Alternate America. [Answer] In the historical 1930s and 1940s, most of the land on Earth was either a sovereign nation or claimed as a colony by a sovereign nation. Yet much of it was very thinly settled. WWII came to some of these thinly settled parts of the world ... * Allied and Axis [weather stations](https://en.wikipedia.org/wiki/Operation_Haudegen) in the Arctic, and even [airbases](https://en.wikipedia.org/wiki/Pituffik_Space_Base#World_War_II). * The war in the [desert](https://en.wikipedia.org/wiki/Western_Desert_campaign). * Anchorages and airbases in the [Pacific](https://en.wikipedia.org/wiki/Leapfrogging_(strategy)). So reasonably your fictional continent could play a similar role. Without population and industry, there is no military need to occupy all of it, but many sides will want to occupy strategic bits and pieces with airfields, ports, and the like. And if one side uses a location, the other side may try to prevent that use. --- Having said that, I don't see a "forgotten continent" on a world with 1930s technology. There may not be recon sats and GPS, but ships and aircraft are advanced enough to produce rough maps, and then people will go there unless there is a substantial effort to prevent that. You might get away with a population density similar to Australia a century ago, but there might still be enough for trappers from one side to notice and report the radio station being installed by the other side -- weeks or months later, as the letter finds the way to a friendly coast. ]
[Question] [ In the future, a variety of different technologies to evade detection are employed, such as harmful sensory input that renders one incapable of perceiving the object that attempts to evade detection even if his/her eyes are looking directly at it, early experiments in light-bending, or just "Stealth aircraft, but better". New technologies are employed to counter this. What I am wondering is whether gravimetry is a potential solution for a military counter such stealth technologies. Can a set of sensors that detect gravitational fields be used to accurately determine whether something is present in an area that is not supposed to be there? For instance, could a setup like what LIGO used, but miniaturized to be mounted on a truck-sized platform provide data such as "There's a human-sized object with a mass of around 1 ton two kilometers from here", or "multi-ton aircraft having such-and-such altitude is located 30 kilometers from here and is moving in such-and-such direction" with enough precision to guide either a conventional or nuclear missile to the location of the object, or are gravitational sensors incapable of being precise enough for this task? [Answer] According to [this source](http://www.tapir.caltech.edu/%7Eteviet/Waves/gwave.html), the amplitude of a gravitational wave from two masses rotating around their common mass center scales with second power of distance between masses, fourth power of rotation frequency, first power of mass (total, the formula provided uses two equal masses) and minus first power of distance to the object. The problem here is that [LIGO detects waves](https://www.ligo.caltech.edu/) that originate from objects whose masses are multiple of the Sun's, over distances which are nowhere as long, and of frequencies that are decent, astronomy wise (1Hz or more). So, a gravitational wave caused by a moving human against a stationary human would differ from those that are detected by LIGO by (-31+16-4\1-6\2) = -30 orders of magnitude. Here first -31 is mass difference in orders of magnitude, +16 is distance difference, rough estimate, -1 is frequency difference, considering that a human moving past could be a part of him walking in a circle around the other one, and this actually depends on distance to that human at (-1) power, thus the distance between humans gives a power of -2 to the amplitude of resultant gravitational wave, and -6 is radius difference. So while the gravity waves of a traversing objects do exist, detecting them would require detectors that are 30 orders of magnitude better than existing. But, the gravity wave from Earth revolving around the Sun, not speaking of any binary star, would be about 12 orders of magnitude larger than what you expect to detect, leading to any detector capable of detecting moving humans be completely overloaded by background gravity waves coming from everywhere. That means, no practical detector could exist to detect stealth objects by gravity waves. You might try a different principle, such as using [Earth's magnetic field](https://en.wikipedia.org/wiki/Earth%27s_magnetic_field) as current initiator in humans walking somewhere, and detecting those currents from afar. I expect such detectors to require at least 10 orders less efforts to detect. Yet they would also find and track all of your own unprotected people... And currents created by other magnetic fields would also make them overloaded. [Answer] Gravimetry is the measure of gravitational force, LIGO does measure gravitational waves, which are propagating distortions of space time caused by moving masses. The two things are not the same. Why gravitational waves won't do for your use case, you have already been told by Vesper in their answer, which I won't repeat. Similar reasoning applies for gravitation force: gravity, being so pervasive, creates a mess of background noise in which what stands out is the contribution of the largest/closest object. Since gravity scales with the square of the distance, 1 ton at 2 km distance has the same gravitational effect of $1000000000/(2000)^2$=250 mg at 1 meter. In other words a sandwich, a phone or a walking rat could easily fool and blind your detection system. [Answer] ### Commercial available gravimeter Current commercially available [gravimeter](https://scintrexltd.com/product/cg-6-autograv-gravity-meter/) used for the purpose of geophysics. Typically used to measure down to milliGal range or 1e-5 m/s^2 or one millionth of one g. To reduce error users aim for knowing the position of sensor down centimeter or better via differential gps. A good [DEM](https://en.wikipedia.org/wiki/Digital_elevation_model) 2m resolution near the measurement point with less resolution further away is needed to correct for local topography/hills. In geophysics context they are used to find ore bodies. For submarines they can find mountains. ### Locating a target Where as attempting to locate a 1 tonne target $M\_t$ at a distance of 2000 m $r$ would have a 'g' of $g=G\*M\_t/r^2$ ~= 1.6e-14 1e-14 vs 1e-5 is a considerable gap of sensitivity. This of course assumes you have a large grid array of gravimeters spaced apart so that your distance to target is approximation 2000m from some part of the array. An array is needed since point measurement gravimeters like the linked cg6 does not tell direction and it is impossible to get direction from a single measurement to get a direction of something that is moving you need multiple simultaneous measurements. A LIGO style sensor can certainly up the precision(mostly by increased size and directionality), its not going to up the precision by nine orders of magnitude. ### Why not try some seismic? What would be more plausible is detecting a moving multi tonne object by seismic/acoustic. That is one of the sources of noise for the LIGO project. Geophones and or seismometers are much less expensive then gravimeters and over much better odds of tracking moving vehicles or people depending on terrain. ### Gravimeter are not precise enough. Outside of magic/ pure narrative declaration of it being so. Using gravity to detect light objects is not practical and probably physically impossible due to near impossibility of controlling for all sources of noise ie its raining so now there could be tonnes of mass moving all around the sensors. [Answer] [Military submarines use gravity gradiometry to prevent collisions with underwater objects](https://library.seg.org/doi/abs/10.1190/tle34121498.1?journalCode=leedff). That clearly shows that detecting nearby objects with gravity is possible. I don't know how precise such technology can be, but considering these were used in the 80s and your world is set in the future, I doubt what you want would seem implausible to most readers, particularly if you include a short description of how the technology evolved over time. ]
[Question] [ Note: I'm working on a far future sci-fi setting for a novel series which aims to blend elements of both "soft" and "hard" science fiction concepts. I'm aiming for the series to be as grounded and consistent as possible whilst still allowing some elements of speculative physics etc. Megastructures, including Dyson-scale, are quite common and the majority (>90%) of people in any given star system live in space. One civilisation in the setting has its capital in a binary star system, with the primary being an F6V star which supports one habitable planet and associated habitat swarms. The star has a partial Dyson swarm, primarily used for power generation/beaming. The star's distant companion is a relatively hot and massive white dwarf star (roughly analogous to Sirius B for now until more details are figured out) with a surface temperature of roughly 25,000K. The society in question is known for its high integration with an AI system housed in a Matrioshka Brain around the white dwarf, used for housing uploaded minds, defence and economic coordination, scientific research and universe simulation. The system also supports the civilisation's e-democracy by managing the government and tallying votes from the system's population of several hundred trillion. It is my understanding that a large Matrioshka Brain offers greater computational capacity but suffers from signal propagation delay due to the light speed limit at which individual elements of the brain can communicate with each other. My question is that would the White Dwarf strike a good balance between capacity and computational speed due to the more compact nature of any Swarm/Brain, or would it be more feasible for this structure to exist around a small red dwarf star instead? Thanks! [Answer] I believe it does not matter in your case. If a civilization can build a matrioshka brain, any element in it may possibly have more computational power by itself than everything humanity ever built so far combined. That should be enough for... well, anything we can think of, really. Being closer together in this scenario means that the swarm layers will save a few seconds to minutes per message when exchanging data. So when deciding whether the balance is good, consider if that makes a difference to your world's inhabitants (and plot). When you are computing the meaning of life, the universe and everything, this time saving hardly makes a difference. Also if a civilization has the capacity to build such a swarm, I think it wouldn't skip a star just because it is too compact, or not compact enough. Other factors such as its position in trade routes and civilization borders should be more important. [Answer] # Star Size doesn't matter for the delay If the computational systems of your story are vaguely similar to our physics, their computational power will likely be proportional to the volume and power supply of a "computing block". Let's say all our computing blocks are the same size and the ones closer to the star operate a higher power, while the outer layers operate at lower power. So if I have an AI which needs 50 Zeta-Super-Flops to operate, this will translate to let's say 50 Million Compute Blocks. To create minimal delays between these blocks working together we should pack them as close together as possible. Optimal would be a solid sphere, but in your story we're using a Matrioshka architecture - so power supply through heat from a star must be the most important matter for building our computer. So our compute blocks need to be arranged on one or more layers of a spherical shell. The curvature of this shell will not make a huge difference, since the signals need to propagate on the shell between the compute blocks (assuming we cannot send signals as a shortcut right through the star) And the shells will also most likely have a pre-defined distance between each other (so the waste heat can be propagated to the next shell) Concerning propagation distance - a bigger star will only mean the same amount of compute blocks will occupy a smaller section of the overall shell, the curvature of the section will be less. But it won't result in a relevant difference in propagation delay. A bigger star will simply mean you have more compute blocks and can run additional computation on the other compute blocks. # Surface heat may make a difference Depending on your technology the difference in surface heat may be a lot more relevant, if you can leverage all the heat and your computational power is proportional to the input energy. So the deciding factor for choosing a star would be it's overall total energy output (surface heat x surface area). And maybe the life expectancy of the star might be relevant on the scales we talk about. # Distance to civilization Since the internal delays of the mega computer are not that different for different star sizes I thin the most important factor would be proximity. Because astronomical scales are huge. Having a supercomputer in your home star system, vs. having one a lightyear away makes a huge difference. Even if the computer would be slower, having to wait two years just to send your question and receive your answer will likely dwarf the computation times. [Answer] The Good, the Bad, and the Ugly The good, as others have mentioned, is the delay isn't really an issue — but I've not liked the reasons provided. You can't think of a Matrioshka Brain like a single CPU. It's going to have breathtakingly massive parallelization. There will be CPUs, memory, etc. all over the place. In other words, the problem won't be a whole lot different than workstation designers deal with today when trying to coordinate multiple processing cards with a much (much) slower [backplane](https://en.wikipedia.org/wiki/Backplane). In reality, good programming rids oneself of 99.9% of those kinds of delay problems. Any program large enough or complex enough to encounter backplane (or in your case, light) delays would be expected to be slower. So, no problems. Life is good. On the bad side is the limited solar power available from a white dwarf compared to most other star types. But is this a problem? Not really. You just have more panels, or the civilization lives with a bit less capability. Or they don't even notice because what they have is "normal" for their experience. Frankly, I wouldn't sweat this one at all unless you want a subplot about some mad scientist who needs a bigger computer and keeps arguing that the lack of solar power won't matter.... Gratefully, I can't think of anything ugly about this. The good thing about dealing with a fictional technology in a fictional setting is that there really isn't sufficient science to say that it can't be done. And since you haven't asked if it can be done (thank you!), you're good to go. Rock and roll my friend. [Answer] The universe itself seems to be stable enough to work around the speed of light limitations. Nowhere does any information get passed faster than the speed of light, and this includes celestial bodies where the lightdistance between its extremities are considerably different. Your concerns about the distances needed to build around a white dwarf star immediately raise the question why the white dwarf star's own body does not suffer from these delays. Why wouldn't the Matrioshka Brain be capable of handling this delay that the entire universe is built upon? If anything, it's proven to be a very stable universal rule (pun very much intended). Secondly, I'm no physicist but I'm pretty sure that the laws of thermodynamics state that the computation itself must take a non-zero amount of time (and therefore delay). Comparatively, the speed of light delay is going to pale in comparison to these computational delays. Thirdly, the acceptability of any delay is one of conventional acceptance, not of technical (im)possibility. We accept that the mail (i.e. physical envelopes) takes a day to get to you due to human and vehicle travel times. However, we do not accept the same standard of an email, because we understand that there isn't a physical travel process involved that inevitably delays the delivery time. Any system that would be built would inherently be built in the understanding that the inevitable delays are inevitable. Or, to use an analogy, no one is going to buy an IKEA flatpack, transport it home go through the laborious process of constructing it, and then be surprised that there's IKEA furniture in their house. That what they knew they were signing up for. ]
[Question] [ Suppose there's some strange group that decided to try not consuming any bacteria (which are, basically, everywhere. and very small). On earth, today. What would completely forbidding the consumption of bacteria entail for these people? What foods, if any, could still be consumed? How would one drink? How could a person live? [Answer] If they have no objection toward killing the bacteria before eating, they can use gamma irradiation to zero the bacterial charge of any food and therefore eat everything. Gamma irradiation, by using radioactive cobalt, is used today to sterilise food and objects. [Answer] I'm going to ignore the feasability of actually achieving this and assume they have a magical filter in front of their mouth that disintegrates all microorganisms that passes through. Unfortunately, their lives would probably be pretty miserable. First, the immune system. There's a hypothesis called the hygene hypothesis[1] that posits that allergies and autoimmune conditions are caused by a lack of exposure to pathogens; the immune system effectively gets bored and starts attacking benign things such as food ingredients - or, worse, the own body. With absolutely no bacteria coming into the system the adaptive immune system would be completely dysfunctional at best, and actively causing chronic hyper-MS-Lupus-Arthritis at worst. Then, there's the gut microbiome. Research in recent years has shown that the gut-brain axis[2] is surprisingly strong, with things such as mood and brain development being heavily influenced by chemicals produced by your gut microbiome. Without any microbiome, it's hard to say what would happen, but it probably wouldn't be pleasant. Gut bacteria also participate in digestion, so without them they would most likely be malnourished as the body can't easily break down complex nutrients that the microbiome would otherwise be doing. [1] - <https://en.wikipedia.org/wiki/Hygiene_hypothesis> [2] - <https://en.wikipedia.org/wiki/Gut%E2%80%93brain_axis> [Answer] ### Easy as Thanksgiving Turkey! First off, we are going to dispense with the objections in comments and elsewhere regarding the human immune system, omnipresence of bacteria, etc. You're talking about a group with a particular philosophy. Obviously, their philosophy is much like that of some radical non-violence types who sweep the ground they walk on so they won't tread on a bug. Of course, many bugs are too tiny, won't be swept up and will be trodden on all the same. Therefore, we're not worried about bacteria floating in the air, or the normal flora of the body. No, our goal is simply to serve up a delicious meal that is devoid of living bacteria. Basically all they need is an autoclave. Yep, the same machine that sterilises surgical instruments will not only sterilise Aunt Sadie's favourite silverware, but will also cook the turkey and trimmings! Autoclaves function by pumping steam into a sealed chamber and pressurising the chamber. The inside of the chamber is typically 270deg, and cooking time should probably be 45min to an hour or so for a good sized turkey. Here is a [video](https://www.youtube.com/watch?v=BCC51vCx7C8) of an actual turkey being cooked in an actual autoclave, and is thereafter eaten by the actual person who cooked it. Skip to about 0:30 for the meat and potatoes. Apparently, what came out of the autoclave was hot and edible. Yum! ]
[Question] [ In the modern world, a lot of products around are from oil-based derivatives or processed organic compounds. Ranging from clothing, footwear, insulation, cars, computers, phones, etc. People are not aware they are surrounded by oil-based products. Is it possible to replace all these products with alternatives in the quantities the modern world is accustomed to? Would we need to move back to the middle ages, where there wasn't any electricity as the world production of electrical cable insulation is not possible due to production cannot meet demand? All our communications sooner or later will require plastic insulation on metal wires, so wouldn't there be any more mobile communications? Therefore, if we don't have any oil, will it be the end of computers as the PCBs are made from plastic? Would it be the end of modern civilisation if there wasn't no oil? [Answer] Short answer: Yes. Longer answer: It depends. So, you correctly pointed out that oil has a multitude of uses. From simple lubrication, to making plastics and other materials, to being used as fuel. In theory, it's not outside the realms of possibility given enough time that alternatives could be sought for every use that oil currently provides. However, oil and its products have a number of unique properties that thus far have not been replicated. Consider plastic - despite its environmental problems, plastic has many useful properties - which is why we use it. It's cheap, non-porous, easily manipulated into different shapes and different properties, It's resilient, etc. Plastic has a lot of useful properties which is why it's used so much. If you look at 'Green Alternatives' currently, many of the options are unable to fulfil all the things that plastic does - whether it's a product that is more expensive, or degrades too quickly, not resilient enough etc. Case in point, plastic straws vs every other option - there is a reason why governments have had to use legislation to compel the change because the alternatives aren't good enough (and still aren't good enough - Screw you, paper straws!) And so it currently is for each and every product or use of oil - there are alternatives currently - they just aren't as good. I will grant that necessity is the mother of invention and that we would (in time) come up with alternatives - but society would still have radical changes, to the point where you could definitively say 'It was the end of Modern Civilization' but conversely, you would also say in hindsight that it was the dawn of 'The Next Civilization'. [Answer] ## It depends on if there is a huge amount of reliable energy, probably nuclear, or not Is it overnight? Does the society in question see it coming and invest in almost ludicrous amounts of nuclear (or hydro, or geothermal, where appropriate) energy? Or have good, cheap fusion power? With enough energy at a sufficiently low cost, alternative feedstocks (CO2, sugar, coal, wood, etc) could provide enough hydrocarbons for the manufacture of important parts. Over time, the chemicals and materials industries can adapt and replace a lot of oil based plastics (once again, taking advantage of cheap energy). If they get caught on the hop or try to survive on just solar and wind, they go back to the early Modern period, or worse. Electricity prices spike just as cheap energy is needed to create alternative chemical processes. See: Europe right now, if not for Russian gas and French nuke plants. Now, take away all plastics and petrochemicals.... [Answer] Yes, about 100 years ago. Oil essentially saved modern civilisation from collapsing due to peak coal in the early 20th century, when many major coal-producing countries saw their output decline, most notably the UK. (And it's no accident that it lost its global hegemon position at right about the time it stopped being the world's biggest coal producer.) Oil is not only a more versatile alternative; it also offers a greater concentration of energy than coal, can be burned more efficiently, and oil-powered engines require much less maintenance too. With such an energy bonanza at its disposal, the world economy could afford to do all sorts of things, including mining otherwise uneconomical coal deposits. Without oil riding to the rescue in the nick of time, the Great Depression would have started a bit sooner and kept going until the economy shrank enough to no longer rely on coal - possibly all the way down to pre-industrial levels. [Answer] #### Yes and No Technically there are alternatives to fossil fuels, but they are not enough. Hydroelectric power and wind in some countries provide more than 50% of the local electricity needs, but on the world scale the percentage shrinks. Nuclear as well is not enough. Some important Uranium mines already have estimate reserves for less than 20 years and currently nuclear is supplying a small percentage of the world energy. Transport: batteries are useful only for urban short range transport, the rest would need to move to trains. Biofuels are the only alternative, but they are not enough, they would probably be reserved for shipping and transporting goods in places where the trains do not arrive. That would be the end, or close to for air travel, except maybe for diplomatic missions, emergencies and vital stuff. Some plastic are already made from vegetable matter. A lot more can be done, also paints and other chemicals can be derived from vegetables, it will be a lot more difficult though. However there is an alternative, [cook](https://en.wikipedia.org/wiki/Hydrothermal_liquefaction) sewage sludge with geothermal energy. That could provide enough oil for the most important chemicals derived from oil. The rest would probably be used as fuel for military equipment and what is left of air travel. Already if you look the current situation you can see that out of a world population of 8 billion people less than 1 billion of them use plenty of energy, another two or three use moderate amount of energy, the rest has to cope with more or less scarcity. So if fossil fuel were exhausted the overall world economy would shrink. The number of people used to abundant resources would drastically shrink. But that would not be a complete stop, just more extreme inequalities. ]
[Question] [ I'm trying to create flight by mathematical adjustments that don't actually violate the laws of thermodynamics. The obvious thing to do would be to neutralize gravity, but that doesn't create directional thrust. My thought is that I could transfer momentum between the flier and "any nearby object" (usually the ground) in order to generate thrust. I know that I'm conserving momentum with this, but is there a clause to the laws of thermodynamics that I'm unaware of that would ruin the math? In my mind, it's identical to using an exotic particle to carry the force, the same way that photons carry the electromagnetic force. [Answer] There needn't be any fundamental difference between "magical" momentum transfer and the everyday kind. Though of course, with any fictional physics, there is by definition a limit on how much detail you can go into without breaking known physics. If you're specifying that there is some unspecified force carrier, then it's no different to a pool cue hitting a ball, or a magnet grabbing a paperclip, until you get into the detailed particle physics of this force carrier. The important thing is that if it exists, we can presume that it allows for an unbroken chain of accounting for both energy and momentum, even in distant interactions, which is the problem that "real" gauge bosons appear to solve (except for gravity). Force carriers also solve potential problems with the second law of thermodynamics, in a similar way. Because your aircraft only directly interacts with the local force carriers, it doesn't matter what, if anything, ultimately "receives" the force. So whether the aircraft is accelerating "against" the Earth, or in an infinite void, the entropy of the system is initially only a matter of the aircraft and the force carriers. Those might interact with the Earth, increasing its entropy, or they might just spread out forever, which would constitute an increase in their own entropy. The important principle is that if everything is always accounted for at the (sub-)micro scale, you don't end up with problems in the big picture. [Answer] The momentum must be transferred to some other object in a straight line (or, well, a geodesic, but that's a straight line for most practical purposes), or else you will violate conservation of angular momentum. You will also have to expend or absorb energy appropriate to the resulting acceleration, or you will indeed violate thermodynamics through conservation of energy. Hovering place or translating at constant altitude would require no energy, but changing altitude (or more precisely, changing gravitational potential) or accelerating in any direction must require energy. [Answer] ## The obvious violation here seems to be Newton's 1st law "An object at rest remains at rest, and an object in motion remains in motion at constant speed and in a straight line unless acted on by an unbalanced force." In your setup, there is no unbalanced force acting on your jumper, therefore, you can not just repel yourself from the Earth without creating a new force to unbalance it. So, while shooting the Earth away from your feet conserves momentum, this requires an unbalanced force. ## But since you asked about Thermodynamics... This is less obvious, but there is a narrow band of understanding in which this might sort of work within the laws of thermodynamics. The 2nd law states that energy must travel from a state of higher entropy to lower entropy, and not in the opposite direction unless acted on by an outside force: closely resembling Newton's first law of motion. In layman's terms, it means that heat energy moves from a warmer area to a cooler area, but there are some substances that are quantumly synchronized so that they have zero entropy (like liquid helium) in which energy can travel in any direction it wants seemingly defying several physical laws. In liquid helium, heat can actually go flow from cold to warm just as easily as vice-versa. Since momentum is just highly organized thermal energy, we can posit that if you could quantumly synchronize yourself and the ground around you, that you could use the thermal energy in your body to propel yourself at speeds up to the speed of sound. This does not violate Newton's 1st law either because because you are using the heat in your body as your outside force, and are becoming colder to perform your super jump. The caveat here is that the physics that allow this sort of thing seem to only work at temperatures of about 2 Kelvin ... so probably not something that can be achieved in any practical context, even if it is theoretically doable... but it is a good starting place for techno babbling your superpower. [Answer] ## You seem to violate conservation of energy Take the normal situation: the aircraft carries a potential energy in the shape of flight height that will accelerate it down as soon as it does not exert a force $F\_u$ upwards through its wings, that is exactly the same as the gravitational acceleration $F\_g$. To stay at the same place, $F\_u=F\_g$. So a Net-0 Force to stay at the height. There is no upwards momentum, great... but to keep that situation you do pay with your floating system converting energy from some potential to acceleration upwards. In a normal plane that is chemical fuel that is burned into heat, which creates motion by expanding gas. In other words: we need to pay with Work $\vec{W}=\vec{F}\times \vec{s}$ to stay afloat by some means (other than actually moving upwards) because otherwise, the work of mass acceleration will bring the two bodies together. Typically, that work is done (like in a helicopter) by accelerating air downwards instead of you - the work performed is then the mass of air multiplied by the acceleration from the rotor and the distance the particle move, resulting in an actual work term that the machines floatation device performed. Let's call this world $W\_m$. To get the full picture, you need to look at the many partial energies of the item: If you plot the (potential) Energy from height $E\_h$ in such a way that the ground is 0 and any height is a positive value, then any height will put a positive value of potential energy on that graph, which is strictly dependent on the flight height $E\_h=mgh$, and it is changed by the work up as well as the work by gravity $\Delta E\_h(t)=\int\_0^t(W\_u)dt+W\_g\times t$. The Gravity term is much simpler because on a grand scale you can assume gravity is a constant with a fixed direction (downwards), so we can simplify gravity as a negatively defined value. If the machine stays level, this should be 0, but that is not the work performed by the floatation device but the work imparted on the flying machine. Now you also need to plot the chemical Energy of the fuel tank's contents $E\_f$, which is dependent on the drain of the tank. These drains are the work paid to the machinery to stay up ($W\_m$) and the work to go forward ($W\_f$), $E\_f=E\_{f0}-W\_m-W\_d, the energy in the tank is the starting energy minus the work for the machinery to stay up and the work for directional movement. Finally, you need to plot the kinetic energy, which is $E\_k=\int\_0^t{W\_f-W\_d}dt$, the energy forward is the work forward (assuming a vacuum) minus the work induced by drag. All the work terms from the plane drain from the fuel, so from an energy standpoint, those are paid for and conservation applies. The other two terms, $W\_g$ is 0 if we don't drop, but $W\_d$ is not 0 on just the plane alone. But we had a different term for staying up than work for being up: $W\_u$ and $W\_m$. $W\_m$ and $W\_d$ are results of Newton's third law, ACTIO = REACTIO: the work from the drag-force on the plane imparts the very same amount of work on the air in opposite direction and is thus net energy neutral over the full system, the gravitational pull towards earth imparts the very same amount of work on the planet as it does on the plane, so it is net-neutral on the full system and so on. In short: energy conservation applies if you include every factor, but not if you just skip on items. ## You need to pay for work So, as pointed out, you need to pay for the work you want: staying up costs work (as the machinery to stay there is not free but moves air instead of letting you rest on a tower), and going somewhere costs work (by operating the device that provides the uplift). Even if you conserve momentum, you can not trick Newton or Thermodynamics. You will never get energy-free movement, you will always have to pay with work. ]
[Question] [ I have a planet about 2 Earth Radii large, and even at a lighter Density this puts it squarely in the 10 Earth Mass Range and about 2.5g. It's about 90% ocean, has a thick atmosphere, and near constant storms. I don't need this to be a specifically human-habitable world, it's intended for big hexapodal aliens, however I would like to see if I can tweak the gravity to be more Earth comparable, somehow, like 1.25-1.5 g instead for more dynamic mountains/geological features, and ideally also megafauna and creatures that can fly. Are there any (with some wiggle room) scientific ways I can lower the gravity/mass without compromising the planet's stability (making sure it has plate tectonics and oceans and weather etc.) - Highly improbable but possible is very much welcome. Barring that, any absolutely wild sci fi concepts would be handy too. [Answer] ## It has a thicker crust and mantle, but an Earth size core. To achieve 1.25-1.5 G your planet needs a mass somewhere between 5 and 6 Earths, but it has a volume of 8 Earths. Earth has a density of ~5.51 g/cm³, but you need a density of ~3.44-4.13g/cm³. This is right in the same approximate density as Mars which is 3.93 g/cm³; so, we know for a fact that rocky planets can form at this density. The Earth is more dense than Mars because it has a proportionally larger iron core, but Earth and Mars's mantle and crust are largely composed of silicates and oxides with much have much lower average densities in the 2–3 g/cm³ range. Since the Earth's magnetosphere extends 6 to 10 times the radius of Earth, it means that if you put an Earth sized core in a super Earth with twice the radius, that it would still be protected from solar radiation while significantly increasing the planet's mantel-to-core ratio. In fact, if you kept the core at exactly Earth size, you would actually drop plant's density to ~3.2g/cm³ giving you a surface gravity of just 1.16g making it a quite comfortable planet for humans to walk on. [![enter image description here](https://i.stack.imgur.com/ckgB3.png)](https://i.stack.imgur.com/ckgB3.png) [Answer] Changing the metal buildup of the core When considering the overall mass of a planet (especially when it's solid), it's what's under the crust that matters. This is because the crust of Earth relative to the core is comparable to the thickness of a skin of an apple compared to the inside of the apple. Assuming that your Super Earth has a similar core build up to our Earth, it's going to have mainly iron & nickel. Iron is a pretty necessary metal to have in your core, as [it's what produces the magnetic field](https://astronomy.com/news/2021/09/when-north-goes-south-is-earths-magnetic-field-flipping) that keeps us safe from the Sun's solar winds. Along with that, iron isn't too dense of a metal, with a density of [7.87 g/cm^3](https://sciencetrends.com/the-density-of-all-metals/). However, the nickel in our core doesn't provide enough benefit to argue it staying, along with it being denser than iron, at 8.9 g/cm^3. Thus meaning, we could change out this nickel for a much less dense metal, such as Titanium (4.51 g/cm^3). This would make your planet a lot lighter, along with not having much detriment on the integrity of the planet. ]
[Question] [ Closed. This question is [off-topic](/help/closed-questions). It is not currently accepting answers. --- You are asking questions about a story set in a world instead of about building a world. For more information, see [Why is my question "Too Story Based" and how do I get it opened?](https://worldbuilding.meta.stackexchange.com/q/3300/49). Closed 11 months ago. [Improve this question](/posts/242007/edit) In my story, the megalomaniac wants to build a planned city, driven by a delusional utopian vision. Where should she site it? Assume no political limits. Assume no budgetary limits. This is only abut the geographical features of the site. Assume the misguided planners are dreaming of a paradise, not driven by economic imperatives. Obviously cities exist in sub-optimal places, but that's not what they want to build. It should be in a region with *low population density. This is a tricky one. See my question is about hidden gems, untapped desirable spots on planet earth. And maybe there are none because people tend to exploit resources and have had a few hundred years of free movement in which to do so, but it's worth a think. I'm sure next to Paris is a good spot for a city, but that's cheating because it's already taken. I'm not talking about totally empty, but in a county with under 60 people/km² would be best. For example, all of India is out. The dictator is looking for a greenfield site for a big city. ## Climate I'm not sure exactly what climate is ideal for a city, willing to hear your thoughts. [Some academics have said that the ideal temperature for economic productivity is 13°C](https://www.theguardian.com/environment/2015/oct/21/perfect-temperature-for-economic-success-is-13c-climate-change). I'm a little sceptical that research – partly because it is purely correlative. Paris has a mean temperature of 12.8° has done passably well at the ole city-development. A more deductive, less inductive argument: the ideal temperature is one where you don't have bother about insulation and heating, makes life a lot easier. That would be about 20-21°, the temperature humans like best. ## Low seismic risk Basically anywhere red on this map is out: ![seism](https://www.esa.int/var/esa/storage/images/esa_multimedia/images/2004/07/seismic_hazard_map/10207430-2-eng-GB/Seismic_hazard_map_pillars.jpg) ## Low risk of tornadoes/hurricanes/damaging storms ![storm](https://spaceplace.nasa.gov/hurricanes/en/cyclone_map_large.en.jpg) ## Thought this dust map was pretty interesting too while we're doing maps. Dust is bad. ![dust](https://www.researchgate.net/profile/Nadhir-Al-Ansari-2/publication/276048930/figure/fig1/AS:294590000189440@1447247137232/Global-Dust-Potential-Map-After-DTF-2013.png) Extreme dry seasons aren't good because they cause problems with dust. Some places (Lubumbashi, Serenje, Huambo) tick all the other boxes: moderate climates in most ways, no storms, no earthquakes, but they get dusty in the dry season. Dust is a bigger problem than people who haven't lived with it realise: bad for all kinds of machines including computers and the human machine. ## Excellent map of both earthquakes and storms. White means go. ![mapmap](https://i.stack.imgur.com/6PDXv.jpg) [Answer] # Amapá, Brazil The north of Brazil strikes a nice balance between all your requirements. It is just to the south of the Atlantic hurricane zone, and far from the seismically active north and west faults along the South American Plate. At the same time, it is the most sparsely populated of the Brazilian coastal states, with just 5 people per square km. As a bonus, it has a low chance for dust and a warm climate year-round (high of ~32C and low of ~24C). Amapa's coast on the central Atlantic makes it a great place for a city with unlimited money to spend on new infrastructure. Currently it is neglected by the Brazilian state, but you can drop a sack of cash to set up docking facilities and easily ship in materials for further construction (and ship out any trade products). [Answer] # 20.8°E over the equator This is in the north of the Democratic Republic of Congo. No hurricanes or tornados. * Very low on dust rate (I specifically looked for that small pale green blob over the north of the DRC in the map). * No seismic hazard. * Currently in an isolated place in the middle of a dense tropical forest. * The nearest cities are [Mbandaka](https://en.wikipedia.org/wiki/Mbandaka), some 282 km west of this place and [Boende](https://en.wikipedia.org/wiki/Boende), 32 km to the south-southeast. Mbandaka is a big city, while Boende is a small town. There are other small hamlets and farms closer, but they are just that: small hamlets and farms. They are along the unpaved M8 road that passes roughly 6.6 km from there to the northwest. * About the climate, it should be very similar to Mbandaka and Boende climates. Mbandaka's year's average low is 19 °C and average high is 31 °C. Boende's years's average low is 20.4 °C and average high is 30.4 °C. Both places have very little (< 2 °C) variation from the coldest to the hottest month. I.e. this place has a temperature that is seldom outside the 18 to 32 °C range and it varies very little in the year. * Also, it features moderate rainfall. Not too much but nor too little. [Answer] Here's what I've found – Corsica – No hurricanes, tornadoes, or earthquakes, excellent location (especially for an air base), and [Bonifacio](https://en.wikipedia.org/wiki/Bonifacio,_Corse-du-Sud#Climate) averages 10.5° in its coldest month, 24.8° in its hottest. The population density of Corsica is 40/km² North coast of Tasmania – Population density of Tasmania is 8.3/km², but 40% them are in Hobart in the south. As a negative, there is a proneness to earthquakes, but only VI on the [Modified Mercalli intensity scale](https://en.wikipedia.org/wiki/Modified_Mercalli_intensity_scale), which may not be a dealbreaker. The [climate](https://en.wikipedia.org/wiki/Devonport,_Tasmania#Climate) is colder than Corsica, but never extreme. Coast of Suriname – If you like it tropical. Southeast of the hurricane belt. [Coronie district](https://en.wikipedia.org/wiki/Coronie_District) is coastal but has less than 1 person per km², the [climate](https://weatherspark.com/y/29323/Average-Weather-in-Totness-Suriname-Year-Round#Sections-Temperature) averages 26°, which is a few degrees warmer than it should be but not much, and because it's equatorial there's little seasonal variation, and there's no dry season. Drawback: mosquitoes. Ireland, possibly Kilkenny – Ireland is [unique](https://64.media.tumblr.com/02b1616847aa8d7a02cf30cdbf16f710/326ad7997d9af046-ef/s1280x1920/821de3ce9eb65031c0a8fc530bbc7bf68616002e.jpg) in being depopulated over the past 180 years. There's probably some historical reason, but it means what is still a UK-like climate, known to support advanced civilisation, is empty. I pick Kilkenny because it's close to Europe while still being empty. It's about the least seismically-active place in the whole world. Southern coast of Buenos Aires Province – "Hey that's cheating you said next to existing major cities was cheating you cheater". No, Buenos Aires city is 450-500km from the southern coast, outside the province. The coast is largely unpeopled, is too far south for mosquitoes and has no earthquakes or storms. The [climate of Mar Del Plata](https://en.wikipedia.org/wiki/Mar_del_Plata#Climate) has a mean of 7.5° in the coldest month and 20.4° (aka 'room temperature') in the warmest, and has the rain spread through the year. (PS: I overlooked that this place has a lot of tornadoes) Thanks for all the replies so far. [Answer] I volunteer [West Alton, Mo](https://en.wikipedia.org/wiki/West_Alton,_Missouri). Pluses: * Not a lot of people to clear out. * Good access to water, transportation, and communication * Highly defensible position between two rivers Minuses: * Currently permanently a flood plain. Lack of residents makes this something that it would take an evil genius to solve. * Occasional tornadoes * Can get earthquakes up to 5.3 or so * Not remote ]
[Question] [ So in my universe, there's only a single planet, contained within a spherical shell. Orbiting around it is a dragon, holding a "sun" for lack of a better word. This sun is not a star as we know it in our universe, but it does provide light and warmth to the planet in the same way. The universe is magical and not bound by science, but to make it feel more real, I do want to figure out the math regarding size and distance. How far away and how large would this sun need to be, to be visually indistinguishable from how we experience the sun on Earth? [Answer] Part One: A Globular light source emitting light in all directions. The question says: > > How far away and how large would this light source need to be, to be visually indistinguishable from how we experience the sun on Earth? > > > The light source would have to be rather far away to be visible from about half of the surface area of the planet at any one time, as the Sun is from the Earth. The question doesn't describe the planet so it could be much larger or smaller than the Earth. It is impossible for a globular light source spreading its light in all directions illuminate exactly one half of a spherical object, because the rays from the light source would have to be parallel to illuminate exactly half the spherical object, and the spherical light source would have to be infinitely far away for its beams to be parallel when they strike the spherical object. In the case of Earth and the Sun, the Sun is about a hundred times as wide as the Earth and it's distance is over ten thousand times the diameter of the Earth. And you can make the light source much bigger and father away, relative to the planet, than the Sun is to Earth, or make it much smaller and closer relative to the planet than the Sun is to the Earth. If you want the light source to have the same angular diameter as seen from the planet as the Sun from the Earth, you have to keep the ratio between the diameter and the distance of the light source the same as for the Sun and the Earth. If you want a relatively small and nearby light source but want about an entire hemisphere of the planet to be illuminated at any one time there will be a limit to how small and close the light sources can be. If it get too close it will illuminate only a part of one hemisphere at a time and many parts of the planet will be in eternal darkness, which is not eh case on Earth. So now I will have to draw a picture with words since I don't have a drawing program, and you have to draw it yourself or picture it in your mind's eye. Picture a circle, representing your planet, with a long line though the center of the planet. Put a dot on the line representing the light source. Draw a line from the light source to graze the circumference of the circle representing the planet. Draw a line from the point where the line from the light source grazes the circle to the center of the circle. There should be a right angle of 90 degrees at the the pint where the angle from the light sources intersects the lien frm the circumference to the center of the circle. You have now made a right angled triangle. The angle at the center of the circle representing the planet, and the angle at the light source should add up to 90 degrees, but they don't have to be equal to each other. In order for the light source to illuminate exactly one hemisphere of the planet the angle at the center of the planet has to be exactly 90 degrees, the angle where the lien from the light source grazes the surface of the circle/planet has to be exactly 90 degrees, and the angle at the light source has to be exactly zero degrees, which is impossible in a triangle. So the light source will be unable to illuminate exactly one hemisphere of he planet, because there will be a part of the near hemisphere in shadow where the curve of the planet blocks the light from the light source. Since you want approximately half of the planet illuminated by the light source at any one time, you need to figure out how close to a full hemisphere you want. If, for example, you want the angle at the center of the planet to be 75 degrees, the angle at the light source will be 15 degrees. If, for example, you want the angle at the center of the planet to be 80 degrees, the angle at the light source will be 10 degrees. If, for example, you want the angle at the center of the planet to be 75 degrees, the angle at the light source will be 5 degrees. If, for example, you want the angle at the center of the planet to be 89 degrees, the angle at the light source will be 1 degree. So you could draw diagrams and measure the ration of the line between the light source and the center of the planet to the line from the center of the planet to the point where light grazes the surface. Or you can use trigonometry to calculate the ration and see how many planetary radii the distance to the light sources is with the proportion of the surface you decide to have illuminated. The planet is supposed to be otherwise like Earth, and so it should have a breathable atmosphere similar to Earth's. Earth's atmosphere refracts light, bending it down to illuminate areas a few degrees beyond the bulge which cuts off light in a straight line, so the planet should not be too unlike Earth if the line from the center to the edge where light grazes the surface is just a few degrees. Part Two: A disc like light emitter with parallel rays. Of course the light source doesn't have to be a spherical light source emitting light in all directions. It could emit light from a disc aimed at the spherical world, and that light could be parallel like laser light. Because the light rays would be parallel in that case, the light emitting disc would have to be at least as large as the diameter of the spherical planet, in order for one entire hemisphere to illuminated. If the light emitting disc pointed at the planet has the the diameter of the planet, and also has an angular diameter of about 0.5 degree, at the distance to the planet, my rough calculations go like this: One half of a degree is one 720th of a full circle of 360 degrees. The circumference of a circle is 2 times pi times the radius of the circle. Using 3.14159 as a good enough value of pi, The radius of a circle is equal to 57.295 degrees of the circumference. Since the light disc is equal to the planet's diameter and to 0.5 degees of the circumference, the radius of the circle and the distance between the light disc and the planet is equal to 114.5916 times the diameter of the light disc and of the planet. If the planet has a diameter of 6,371 kilometers, the mean diameter of Earth, the distance to the light disc will be about 730,063.4 kilometers. If the light disc is more than a few tens of thousands of kilometers closer than the calculated distance, its disc will appear to be larger than the Sun appears from Earth, and if it is more than a few tens of thousands of kilometers farther than the calculated distance, it will appear noticeably smaller than the Sun appears from Earth. And if the light disc is farther from the planet than the calculated distance its parallel rays will illuminate less than one full hemisphere of the planet at a time. I would be grateful for anyone who improved by answer with diagrams and/or trigonometric calculations. [Answer] ## Distance and size go together. The sun is ~150,000,000km from earth (it varies through our orbit from 152.1Gm at the aphelion to 147.1Gm at the perihelion) and has a diameter of ~1,393,000km. The moon is ~384,000km from earth and has a diameter of ~3475km and is almost exactly the same visible size as the sun during an eclipse. To visualize it (not to scale, obviously), with a lot of rounding: ![](https://i.stack.imgur.com/DulF0.png) ### The simple option The simplest way to choose the size/distance for your draconic sun is to just take the ratio of distance:diameter. The sun is 150Gm away and 1.39Gm across for a ratio of ~108:1. The moon is 384Mm away and 3.48Mm across for a ratio of ~110:1. If you want your draconic sun to be 1000km away, it should be 1000km/108 = 9.26km across. If you want your draconic sun to be 100km across, it should be 100km \* 108 = 10,800km away. ### The complicated option What's relevant here is actually the portion of the viewer's line of sight that the celestial body obstructs. So let's take a look at the angles, using the radius of the bodies: ![](https://i.stack.imgur.com/7IyZP.png) These are pretty rough numbers, but the sun's radius results in a triangle with an angle of 0.267° from the viewer's perspective while the moon's radius results in a triangle with an angle of 0.26°. You'll want your draconic sun to have roughly the same angle. So let's do some trigonometry! The relevant formula here is tangent (or tan): ![](https://i.stack.imgur.com/JPxx0.png) You may be familiar with the mnemonic from trigonometry "SOH CAH TOA": sine (sin) of the angle is the opposite edge over the hypotenuse; cosine (cos) of the angle is the adjacent edge over the hypotenuse; tangent (tan) of the angle is the opposite edge over the adjacent edge. For that angle math above, I'm using arc tangent (atan, or tan-1), which is just the inverse of tan (and there's asin and acos in the same vein). More specifically: $$ tan(\theta) = \frac{700Mm}{150Gm}\\ atan(tan(\theta)) = atan(\frac{700Mm}{150Gm})\\ \theta = atan(\frac{700Mm}{150Gm})\\ \theta = 0.267 $$ If you pick a radius R, you can therefore solve for your distance D as follows: $$ tan(0.267) = \frac{R}{D}\\ D = \frac{R}{tan(0.267)} $$ So if you want the draconic sun to be 100km across (about 3% as wide as the moon), it would need to be ~10,700km away from the earth (which you can calculate on [WolframAlpha](https://www.wolframalpha.com/input?i=50%2Ftan%280.267+degrees%29)), which is close to that ~108x ratio from the simple approach. Note that since this is from the perspective of an observer on the surface these distances are relative to the surface of the earth rather than the center of the earth. [Answer] Size varies with distance. What you are failing to consider here is that the farther away the “sun” is, the bigger it has to be, and the closer it is, the smaller it has to be. Its luminosity also plays a role. Assuming this world has a moon the same size and distance as Earth’s moon, and you want to have the odd solar eclipse now an again, then this “sun” should be about the same size and a little farther away. In other words, it has to be about 385,000 kilometres away, and about 10900 km in circumference (at the equator). If you are a maths nerd, then you can work out how luminous it has to be. If you are not a maths nerd, then grab one off the street! Or buy a calculator. That works too. [Answer] It depends entirely on how far away the sun is. The sun must be further away than the moon (otherwise there would be no eclipses) and at just beyond the distance of the moon the sun would have to be just a little bit bigger than the moon. Alternatively the sun could be 93 million miles away (400 times further) in which case it would have to be 400 times bigger or as big as the sun actually is. Or it could be at any distance between these two with a proportional increase in size (10 time further away from the moon and 10 times bigger etc). [Answer] The answer depends a bit on what you mean by "visually indistinguishable from how we experience the sun on Earth". If only the apparent size of the sun on a specific location is relevant, then the other answers give you a good starting point. However, as soon as one moves over the planet's surface, there is a certain movement in relation to this "sun". If the sun is small and close (e.g. 10000km), the relative movement on the surface would change the apparent size of the sun noticeably while being negligible on our earth (consider that the equator would be 6000km closer to the sun that the poles, the sun would be more than twice as large near the equator). (1) The same would happen with parallax - moving over the surface of the planet would shift the position of the sun compared to what is noticeable on earth. (e.g. in the above example, the poles would likely be in eternal darkness assuming the 23° axial tilt). A closer, smaller light source will also illuminate less of the planet overall Hence, there is only one true option: the size of our sun and the distance of our sun to earth. However, with some tolerances, some lower bound of the distance could be established, where the change in apparent size and position would not be noticeable without modern equipment. The sun would definitively be larger and further out than any reasonably sized dragon you expect. Probably in the order of millions of kilometers (the radius of the sun's orbit must be much larger than the radius of the planet to keep the changes due to parallax and distance small enough). (1) such a system, where the sun is inside the lunar orbit, could also be an interesting setting, though. ]
[Question] [ Basically a planet with a global network of caves filled with gas with occasional openings to the airless surface. The openings would look like underwater brine pools, ranging in diameter from a few millimeters to dozens of kilometers. The deepest the caves go is 12 kilometers deep (from surface) [![Goo Lagoon IRL](https://i.stack.imgur.com/YIC3u.png)](https://i.stack.imgur.com/YIC3u.png) Solar wind strips any gas that exits the openings away from the surface, leaving only a barely detectable thin atmosphere above ground. The atmosphere underground is mostly methane, CO2, and water vapor with some O2 and other gasses. The cloudy surface is caused by organic compounds suspended in the air reacting with light and scattering it, a similar thing happens on Saturn's moon Titan. The planet may harbor simple microbial and colonial life subsisting on what light comes into the cave system from openings, chemical reactions and eating other organisms. So, is this a feasible concept for a planet? [Answer] Think of household plumbing, and the [sink/toilette trap](https://yourniftyhome.com/kitchen-sink-trap/). Basically, it does what you want, it keeps the sewer odors from coming back into your house. That is exactly what you want, but on the other side of the trap. You want the atmosphere to stay inside the cave/sewer from escaping into the outer world. So if you manipulate your sinkholes into traps, with the cave curving back up above the water level in the sinkhole (like a toilette) then yes what you want is possible. Whatever goes between the cave system and the outside world has to navigate through this fluid barrier in the trap. [Answer] Unlike the surface of an ocean or the boundary of a brine pool, the planetary boundary between an atmosphere and the vacuum above it is a very, very gradual transition. For Earth, the highest breathable altitude is 6 km; but the "K√°rm√°n line" (the definition of where "outer space" starts) is at 100km. So, if by "airless" you mean the same air pressure as Earth's K√°rm√°n line, you're going to have dozens of vertical km of unbreathable cave systems between the breathable cave and the surface. If you can accept a more flexible definition of "airless", then you can reduce this distance. [Answer] ## You just described Mercury [Mercury](https://solarsystem.nasa.gov/planets/mercury/in-depth.amp) has a thin oxygen-sodium-hydrogen atmosphere so sparse it is almost a vacuum. Just as you describe, solar wind strips away gases on the surface, meaning Mercury is shrinking fast. > > Instead of an atmosphere, Mercury possesses a thin exosphere made up of atoms blasted off the surface by the solar wind and striking meteoroids. > > > Unlike the planet you described, Mercury has virtually no atmosphere to scatter the light. Because of this, temperatures range in the extreme, from boiling hot by day to frigid at night. The sky is black, possibly because Mercury is [smeared with carbon](https://www.science.org/content/article/why-mercury-so-dark). (Just a thought: if the planet is "airless" and has "no atmosphere," as you say, how do you justify your scattering light? You cite Titan as an example, but [Titan](https://www.nasa.gov/image-feature/jpl/pia20026/organic-compounds-in-titan-s-seas-and-lakes/) has a rich nitrogen-methane atmosphere which react to produce organic molecules.) Despite having no atmosphere, Mercury may have underground lava tubes which could serve as a future human settlement Research indicates that Mercury possesses hollows, holes on its surfaces that indicate potential [lava tubes](https://en.wikipedia.org/wiki/Lava_tube) underground. These tunnels, formed by molten lava flowing from a volcano, could be emptied out to form a network of caves. The concept of an underground cave settlement on Mercury is the topic of many headlines. [Building Subterranean Cities on Mercury "Not So Crazy," Scientist Says](https://www.vice.com/en/article/ypppam/lets-build-subterranean-cities-on-mercury) > > NASA has toyed with the idea of taking advantage of frozen tunnels on the moon as a prime location to build a moonbase. Discovery's Ray Villard explains: the lava tubes would allow for ant farm-like colonies of humans living underground... Recent satellite data reveals that Mercury too might have some of those lava tubes > > > [How do we colonize Mercury?](https://phys.org/news/2016-08-colonize-mercury.html#:%7E:text=In%20the%20case%20of%20Mercury,water%20cycle%20and%20carbon%20cycle.) > > Colonies built inside stable lava tubes would be naturally shielded to cosmic and solar radiation, extremes in temperature, and *could be pressurized to create breathable atmospheres* [italics mine]. In addition, at this depth, Mercury experiences far less in the way of temperature variations and would be warm enough to be habitable. > > > Although these articles go more in depth, the general consensus? Mercury has no atmosphere, but has water sources and potentially lava tubes, which could be used to create a breathable atmosphere underground. The only part of your planet I'd cast doubt on is its organic-compound, light-scattering "airless" atmosphere. [Answer] ## Ice caves? If you take a 'water world' for example a moon like Europa and postulate a thick ice crust many kilometers deep covering its surface its possible that a combination of gravitational stresses and internal thermal dynamics could cause fissures, cracks and caves to form in the ice crust. As heated water from the depths of the planet rises and it could be forced through cracks in the bottom of the ice layer and would melt more ice in the process forming ice domes and channel systems. If/when the flow of hot water and gases ceases or shifted location the underside breaches would re-freeze and could well leave hollows in the crust filled with water and any gasses mixed in with that water. Add in gravitational stresses caused by the moons primary and you would perhaps get 'ice quakes' and water geysers that would cause more fractures letting liquid water under pressure escape both upwards onto the surface and downwards back into the world ocean. Once vented empty caverns and channels would be left behind. After that how long any one system of caves would last depends on how dynamic the whole process of 'ice tectonics' was. A highly dynamic system might see constant turnover and only short lived cave systems. A slower, less frequent process (perhaps even seasonal?) might see some systems last much longer. ]
[Question] [ On my planet, there are 5 continents and a few countries per continent. The continents are arranged as follows (this is Mercator Projection, and there is a large Pacific-like ocean between the two remote sides): [![enter image description here](https://i.stack.imgur.com/iKNcRm.png)](https://i.stack.imgur.com/iKNcRm.png) The 4 corner continents are huge, with areas about the size of the continental US each, and populations of about 10 to 500 million due to geographical factors. Each continent has 1 or more countries. The central continent has only one country. It is about 100k sq km and has about 50 million people. The central country is a democratic republic. The GDP of the corner countries ranges from a few to about 40 Trillion US Dollars in value (USD is important because the values of products need to be compared with Earth). The "central" country (for its superpower status) needs to, in general, overpower the entire world without doing anything wrong or inhumane (for example, colonization is not allowed). One of those requirements is that its GDP needs to be more than the rest of the world combined (around 60 Trillion USD). It also needs to be able to become "independent" in all ways. How can it achieve that, for at least an extended period of time? Looking for just some plausible situations that allow a very small country to have an extremely high GDP. One simple solution is to have some resources such as petroleum almost entirely controlled by the central country - but I'm looking for something a little more clever. [Answer] It begins with Trade. In the early days of sailing ships there would be some trade between the north/south tips of adjacent continents. Now all boat captains (and sailors) know not to chance the waters near the poles (icebergs/fog, there be dragons), and don't dare enter the central pacific (Bermuda-triangle, there be bigger monsters) this leaves the only trade-route west-east via the central part. This places the central island ideally as a trade hub, controlling the exchange-rates between currencies from the four corners, and being a place of refuge and neutrality in times of strife between them. This, over time, would allow the central land to offer credit, to commission it's own fleet of ships to first undercut the trade-prices of the others, then to monopolise the trade between the four - and to become a central hub for banking and stock-investment. In time, they would manoeuvre themselves, leveraging the goods from each corner - worming their way into ownership of large chunks of the industry on the corner pieces, owning lands, leasing to the residents, holding the purse-strings of the rich and powerful there. Arranging conflicts to enable weapons sales (to both sides of course), swooping in like the angel of salvation in times of scarcity or privation (at a price). This would (if managed effectively) give them the keys to the world and pretty-much unlimited power. A wrinkle in the perfect plan might be pirates with bases at the poles who parasitize off the fleet, but they're few and turn tail at the sight of a well-armed group of clipper-escorts. The clipper sea-police always protect the best interests of their masters of the central-isle, censuring any unauthorised trade between neighbours - thus ensuring a monopoly. [Answer] # Have the central people be space native indian stereotypes, like avatar. The central people have a vaguely hippy culture, free views on sex, and are close with nature. They are so close with nature they have advanced to partially control it and have extremely advanced biotech. They are the original inhabitants of the planet, and were driven from the corners. Because they hold vague and unobjectionable positive views, them hoarding all the advanced technology they have which controls nature won't be viewed as evil. [Answer] # [Space Elevator](https://en.wikipedia.org/wiki/Space_elevator) Your positioning of the central continent right on the equator, and the lack of any equatorial land on the four other continents, immediately presents this possibility. As the first point of contact for any interplanetary trade, it makes sense that the central continent would be the richest, whether via direct profit from trade, or via the flow of capital into other supporting industries (financial, manufacturing, services, etc.) Given that any flow of goods, materials and labour necessarily has to traverse through its borders as well, this naturally gives it immense leverage over the corner continents. Want to pick a fight? Well, all they have to do is suspend their exports of Unobtanium for your reactor cells. Want to invade? Well, they have a military twice as big as yours and stocked with the best weaponry money can buy, sourced from all around the solar system. In essence, this would make the four other continents economic vassals of the central continent. [Answer] 2 Words: British Empire. So, that's the real world example - some ideas on how to achieve that in your fictional world: 1: Resource availability - specifically, easy access (e.g. on the surface) to various metal ores that need minimal processing 2: From Thomas Sowell, Navigable waterways (the small country may have rivers that barges can easily traverse) 3: Climate - this is a two-parter - first part is that the small country may have land that is more suitable to intensive farming and the second part is a theory (can't remember the name, sorry) that goes along the lines of - if it's too hot or too cold, the Civilization won't develop - but if you have harsh enough winters that you need to prepare (make shelters, store food etc.) but not so harsh that this takes up all your time - then the society will be forced to develop faster 4: Written Language - this is a biggy as it's probably the biggest accelerator of a civilization - what you could have in your story is that the small nation had access to materials (say Chalk...) that made it easy to develop a written language. ]
[Question] [ Would a tractor beam consisting of a powerful suction force be usable as a method of grabbing targets at a maximum range of about 10yd? This is obviously only applicable when not in the vacuum of space, and would have a vent right before the fan, so as to avoid slicing up whatever was "grabbed". Would this work at all? If so, would a 150 pound creature survive the trip? [Answer] No The fundamental problem with this idea is that technically vacuum cleaners don't 'suck' they just allow the air on the other side to 'blow'. (Go ahead and get all the juvenile jokes out of your system now.) Creating a low pressure zone means that the air will rush in from higher pressure zones until an equilibrium is reached. In turn, this means that even if the nozzle of your I'd-like-to-be-a-tractor-beam vacuum cleaner could create a perfect vacuum (which it cannot), the maximum pressure differential that can be achieved is one atmosphere. That's directly in front of the nozzle - if you're talking about trying to hoover up a person even five metres in front of the nozzle then the air is rushing in from all directions and the pressure differential - and consequent wind speed - is much less. Experiments and accidents involving rapid depressurisation of aircraft and spacecraft show that it is possible for people right next to a breach to be sucked (blown) through it. They need to be right next to it, though - even a few metres of separation is enough to allow them to avoid that fate if they have something to hold onto. You might be able to capture someone some metres further away if you put them on a perfectly smooth, oil-slicked surface... In practical terms, though, if they are close enough to be captured by a big vacuum cleaner then they are close enough to be grabbed by a mechanical arm that can be extended a few metres. Consider also that the "tractor-vacuum" will be creating a vacuum that will result in everything of sufficiently low density being pulled in. So there is no chance of just capturing one person, unless everyone else is much further away, along with all the bags, litter, dirt, vegetation, animals etc filling the sphere whose radius the target person is also within. Note that when Mythbusters were attempting the scuba-diver-sucked-up-by-water-bomber myth that they were unable to maintain a good enough seal to keep hold of the "diver" in order to even get them out of the water, let alone carry them anywhere. Admittedly that was using a pump designed to suck up water, but the results are indicative. In summary - if a person is close enough to capture with a giant vacuum cleaner, they are close enough to grab with a mechanical arm that will use a tiny fraction of the power and will be far more selective. ]
[Question] [ If there happened to be extremely radical conditions causing extremely unique evolutionary results, could a carbon-based lifeform hypothetically “drop” oxygen and carbon-dioxide in favor of an entirely different system of respiration? For example: inhaling an ambiguous gas not comparable to any natural gas on Earth, and exhaling helium. Universe is highly technologically advanced and I’m open to said species being largely to entirely artificial in origin. [Answer] We have already examples of carbon based life forms which do not need oxygen: all anaerobic bacteria do it and are killed by the presence of oxygen. However keep in mind that respiration is a chemical reaction, what one inhales and exhales must be related by a chemical change, for example C, O2 and CO2 or S, H, H2S. Getting helium out in a chemical way is a tad impossible, consider that helium doesn't form any compound, so won't take part in any chemical reaction. [Answer] Fusion reactor. [![fusion schematic](https://i.stack.imgur.com/491sW.png)](https://i.stack.imgur.com/491sW.png) <https://en.wikipedia.org/wiki/Nuclear_fusion#Process> If the key thing here is exhaling helium, a fusion reaction makes helium out of hydrogen. Maybe your ambiguous gas is deuterium. Of course no earthly life has fusion reactions going on inside of them. But you do not specify the scale or time period over which this must take place. Fusion usually involves temperatures and pressures not compatible with carbon based life, but [cold fusion](https://en.wikipedia.org/wiki/Cold_fusion) is not exactly wild eyed science fiction - a lot of people spent a lot of time looking at cold fusion to see if might work. An engineered organism that inhaled deuterium gas, exhaled helium and powered itself by fusion would be a fine creature for a fiction. [Answer] Nope! Even aerobic organisms on Earth don't necessarily breathe diatomic oxygen, and we don't exclusively produce CO2 as waste products. We breathe in O2, and excrete CO2, water, and ammonia (which mammals convert to urea). Other organisms could breathe nitrogen oxides, or sulfur oxides, and excrete all of the above plus elemental nitrogen or sulfur. They could breathe in chlorine or chlorate / chlorite and excrete water, ammonia, carbon tetrachloride, and phosgene. Or, the oxidation/reduction reaction can be reversed, with organisms inhaling hydrogen and excreting water, ammonia, and methane. Or inhaling carbon monoxide and excreting CO2, ammonia / hydrogen cyanide, and formaldehyde. The possibilities are... well, not literally endless, but pretty widely varied. [Answer] Radioactive Decay One of the main sources of helium on Earth is the natural decay of heavy radioactive elements, such as uranium. In some places around the world, notably in the damaged reactor at Chernobyl, there exist colonies of radiotrophic fungus which perform radiosynthesis using melanin. Perhaps the creature you are looking for is a radiotrophic organism which takes in ambient radioactivity. It might then store the radioactive material in a shielded organ, and exhale the helium that would be produced by the decay. Wikipedia: <https://en.wikipedia.org/wiki/Radiotrophic_fungus> <https://en.wikipedia.org/wiki/Ionizing_radiation#Alpha_particles> ]
[Question] [ ## The problem: I want to have a volcanic island with an everlasting lava outflow completely overgrown by (jungle) plants. It therefore follows that plants should also grow above the lava. I know that [volcanic ash](https://en.wikipedia.org/wiki/Volcanic_ash#Volcanic_ash_soils) is very fertile, so the plants can grow well. However, I see the heat of the lava as a problem: if the lava is completely overgrown, the heat accumulates and thus burns the plants. As a solution to this, I have thought of "natural" chimneys, mostly vertical open spaces that remain free of growth and give the heat an escape. I can make a fertilizer and other things with handwavium, however I don't want to change the plants. Can plants with infinite good conditions grow over lava and cover it completely ? And what things do I need to do this ? ## The world: Wealthy scientist Alice would like to work quietly on the solution to end world hunger. However, she is constantly distracted by people: the UN keeps asking about progress, the press for unnecessary interviews, her wife when she would be coming home. All these unimportant things keep her from doing her research. However, recently the evil scientist Bob was defeated by the World-Police™ and his lair of evil, a cozy volcanic island somewhere in the middle of nowhere, is for sale. With its own trench full of lava that drains into the sea and a basement full of stuff made with handwavium. And thanks to the never ending lava flow, the island is also getting bigger and bigger, you get more and more land. So strike today and buy it. Alice strikes, buys the island, disappears from the world stage and calmly develops a super fertilizer. With its own field test on the island. After testing and documenting everything, she gets hit by a flowerpot that fell off the shelf and dies. The flower pot was red and had a smiley face on the side. It was a good flower pot. We will miss you, Charlie, the flower pot. 200 years later, everything is overgrown with plants, the original island is no longer recognizable, and Charlie is still dead. In this initial state, the island is rediscovered.... [Answer] # Lava tubes: Most likely, the perpetual river of lava will move and shift over time, since the fluid turns to rock if it sits for even a short time. It would keep burning a new path. The lave dams itself, backs up, flows in a new direction, or fans out. Lava is very viscous and doesn’t flow like a classical river. If the lava DOES perpetually flow in the same channel, it will likely eventually cool unevenly and form a lava tube. Lava flows have left lava tubes all over the globe. A ceiling of solid rock forms and ash/plants can be growing directly over the lava flows. As long as there is enough insulation so the plants don’t cook, they’re fine. This also has the lovely fun of the ground giving away to a hidden river of molten rock… [Answer] I think you are facing an though problem: * flowing lava is hot, and that heat keeps water away. As long as there is no water, no seed can sprout. Even with a torrential rain supplying water, a plant would need time to grow. That time plus the rain would not make the lava flowing any more. * growing plant need some soil, not rock. Again, soil formation takes time and weathering. The only way around seems to be to cover the flowing lava with a somewhat thick layer of soil (either artificially or by some avalanche) and have plants grow in that soil, while the lava keeps happily flowing beneath it. If the climate is cold, a warmed soil can actually help plant growth. ]
[Question] [ In my world, petrol will not be available anymore and there will have been a crisis ending its availability (the story is set after the crisis). The consequences will be these: Developing and poor countries will regress to some sort of medieval era while stable countries will survive and become independent from the petrol by successfully moving to other sources of energy and advancing the civilization. Basically the world will breakdown in 2 parts. A "futuristic part" with advanced technology composed of the countries that have survived the petrol crisis and another part with poor countries that become more poor due to the petrol crisis. I know that people in some poor countries already live in a similar way but how much can hold done in fiction? I took a look atthe map of the developing countries ([Wikipedia](https://en.wikipedia.org/wiki/Developing_country#/media/File:Imf-advanced-un-least-developed-2008.svg)) and everything seems OK with what I want to write but I'm not sure about the 2 type of countries. Is this realistic? [Answer] The effects of no more petrol depend on several factors including how quickly petrol disappears. If petrol is available for the next 100 years but gradually becomes more expensive, then the change over to other fuels will not cause a major disruption to most countries. The Middle East will be the most affected. If petrol would disappear quickly, we would need rapid experimentation and rapid changes to how energy is distributed. Rapid experimentation will have environmental consequences that will cause trouble in places. If petrol were to run out in the next 5 years, then the dividing line will between countries with strong systems in place that preserve the present structures and those that don't. Places that can adapt more quickly will change and keep going. Places that insist that the world not change will run out of energy (and may face internal upheaval). This rigidity is both government and cultural. To rapidly switch fuels, the population needs to be open to new ideas and cultural changes. Governments would need to support regulations that allow new ideas to serve the public instead of forcing everything into existing forms. If the EU has too strong of regulations, then they will have troubles. The dividing line may be within countries, states, and provinces. At one time, support for shipping was the dividing issue and some places refused to change while other towns did. Those that changed grew and those that didn't are now "quaint Medieval villages". [Answer] It is not as straightforward as it seems. Some third world countries use so little [energy](https://en.wikipedia.org/wiki/List_of_countries_by_energy_consumption_per_capita) that they do not have much to lose from an oil crisis. Then there are countries like Brazil that will suffer in the transport sector, but mitigate the problems in the other sectors because a lot of their electricity come from hydroelectric power plants, what about France that relies heavily on nuclear power plants? Then among the developed countries there is a huge difference in the [efficiency](https://en.wikipedia.org/wiki/Energy_intensity_by_country) of their energy usage. The US here have a lot to lose, because notwithstanding all the nuclear power plants they have they consume huge amounts of fossil fuels. In short I think that in the future you describe the winners and losers cannot be divided in developed/developing and poor countries. The dividing line will cut through the current classifications. [Answer] The divide between advanced and not-so-advanced countries has been a constant in our history: countries which could work metal and countries which could not, countries which could build cities and aqueducts and countries which could not, countries which could sail the oceans and countries which could not, countries which can have clean water and health services and countries which cannot, etc. etc. I don't see any reason for this not holding also in future or in the scenario you depict: developing new technologies will require resources and not all countries will be able to either afford the researches or pay the royalties for using the findings of those researches. And guess what will that lead to? Yes, precisely what you have described. ]
[Question] [ Assuming a human-like entity has the ability to visit a planet that is like (or is, if that makes this easier) Earth during two time periods: 1. A time period where the planet's magnetic field is stable and Magnetic North is at Geographic North, and Magnetic South is at Geographic South; 2. A time period where the planet's magnetic field is stable and Magnetic North is at Geographic South, and Magnetic South is at Geographic North. Assuming also that * there aren't any digital or written physical records from a civilization detailing the magnetic field shift as it was happening; * the human-like entity lacks a magnetic compass to measure the change, and they don't have the ability to single-handedly check the sea floor for magnetic field stripes, at least until they have evidence that the magnetic field has already flipped. # What would be the easiest discernible visible change on a continent for said entity to notice that the planet's magnetic field must have flipped since the last time they visited the planet? [Answer] # Zero evidence to the naked eye It seems like there wouldn't be any evidence that is readily apparent. Humans are not sensitive to magnetic fields, so we couldn't directly perceive the field either before or after. We are dependent upon tools such as compasses to even detect the field as it is today. The only traces that remain of past states of the magnetic field are things we can't see without looking very hard for them, such as the magnetic orientation of rocks. And we need to date the rocks using an independent method in order to see how they relate to the present. And even if periods of reversal can trigger (or be triggered by) increased volcanism, collecting that data would be a non-trivial task that would take months or years of dedicated research. This is all stuff you have to go looking for. None of it will just fall into your lap. Nobody will notice this simply by being generally alert to their surroundings. --- Finally, it seems that reversals typically take a long time, too. From [wikipedia](https://en.wikipedia.org/wiki/Geomagnetic_reversal): > > Most estimates for the duration of a polarity transition are between 1,000 and 10,000 years, but some estimates are as quick as a human lifetime. > > > Given the average human lifespan, it seems overwhelmingly likely that it would not be obvious to a human visitor even if the planet were undergoing geomagnetic reversal at the present moment, because it would not be complete for very many lifetimes, and the transition would be very gradual. They would likely need to take precise compass readings over a long time to detect any change. [Answer] First get an ocean floor map. A well equipped interstellar survey ship could probably achieve this from orbit. What you are looking for is an active spreading zone. (You did say Earth or Earth like.) The mid-Atlantic ridge or equivalent is what you want. Next you need a few ocean-worthy boats, each dragging a high quality submersible magnetometer. Your goal is to map the magnetic stripes in the former magma that cooled into oceanic crust. Other than some variance due to polar drift, the youngest ones (closest to where new magma is coming up) should line up very needly either withthe current field or be in (nearly) direct opposition to it. Grab a few core samples to measure sediment depth, radioactivity, and other signs of age, and you'll be on your way to building a timeline of magnetic reversals dating all the way back to that ocean first forming. There's a great video on magnetic stripes in the Atlantic here: <https://www.geolsoc.org.uk/Plate-Tectonics/Chap3-Plate-Margins/Divergent/Mid-Atlantic-Ridge> When you come back many years later, check your compass and the stripes close to the ridge and you'll see what's happened magnetically (if anything) in your absence. On dry land, you can get some info about magnetic history from volcanic rock, but it will be a huge project to get details approaching a magnetic survey in a spreading ocean. [Answer] No detectable biological effects As stated [here](https://www.sciencedirect.com/science/article/pii/S0079610704001105): * Earth's magnetic field varies between 25 and 65 μT. * MRI systems used for medical diagnosis expose patients to fields as high as 2.5 T. * MRI operators can be exposed to fields up to 5 mT while standing by the patient. Studies have shown that slight biological efects appear only for exposure to a magnetic field of >2 mT. No effects on materials In [this](https://www.hindawi.com/journals/amse/2015/934195/) study, materials were exposed to static magnetic field of ~2 mT. Therefore magnetic fields of 65 μT may not have any significant effect on biology or materials. [Answer] Their are no signatures that would be visible without taking large scale, detailed, and quite sensitive, scientific observations. The examples that come to mind are: 1. There will be an ozone layer depletion associated with the reversal but peak ozone concentrations are so low that you need good instruments just to detect the ozone layer exists. By the time the magnetic field has fully stablised the change will probably be small enough to disappear into the background variation. 2. There will be radiological evidence burned into exposed rock and soil surfaces from the increased cosmic ray and UV flux caused by the weakened magnetosphere and associated ozone depletion but that evidence requires huge labs, contrasting rock units to measure against and fades quite rapidly unless buried relatively deeply quite soon after the radiation event. 3. There will be fossil atmospheric evidence of the ozone depletion but that will be hard [impossible?] to differentiate from a nearby supernova or a glancing hit from a [gamma ray burst](https://en.wikipedia.org/wiki/Gamma-ray_burst) and it won't be immediately apparent to a surface observer. 4. There will be indications that something very strange happened in the [dendrochronology](https://en.wikipedia.org/wiki/Dendrochronology), probably including the lose of some high altitude communities and bizarre growth behaviour in survivors but it would take a board ranging survey to even realise that this was not a local phenomenon let alone the implications and causes. Arrive during a reversal and the changes would probably present a picture of some grand change underway but again knowing what would be very hard without very good instruments and a an extended study period. [Answer] Confused birds If the magnetic reversal occurred extremely quickly, for example "within a human lifetime" as is sometimes suggested as an extreme, it might be possible that this would mess up the migration patterns of long-lived birds. Certain migratory birds can live decades, and if the shift is occurring within 100 years, the movement of the magnetic poles might be significant enough that some birds might not have time to adapt as they would if the shift occurred on a 1000-10000 year timescale. As to actually observing this, maybe the visitor would notice that there are less of a specific species of bird around than there are before? It probably wouldn't be obvious to anyone who hasn't specifically studied this, but an ornithologist might notice. [Answer] ### Difference from prior observation. The primary evidence would be a change from the previously recorded magnetic field. The entity if they are the least bit scientific /methodical / profit oriented they would have observations from previous visit(S). Then a quick comparison would indicate the change, Likely causing further investigation if they are surprised or wanting confirmation. [Answer] ## Recent meteor strike (I think) An iron-rich meteorite struck the ground, leaving a fair sized Meteor Crater full of little novelty grains of iron. If these solidified in a magnetic field, and were compressed into surrounding sediment, there ought to be traces of magnetization if you measure very carefully. You compare those to the current magnetic field and see if they're backward despite the recent age of the crater. Caveat: I don't know if that really works. [Answer] Extinction Events The magnetic field of a planet helps stop background radiation of space, and it's believed that during a pole switch, the field weakens to allow radiation through, although that's just currently a theory and doesn't have much evidence for it. What does is [magnetoreception](https://en.wikipedia.org/wiki/Magnetoreception) - the phenomenon of migrating animals using magnetic fields for direction. Essentially this means that every major migration pattern on the planet will flip and lead to the extinction of the majority of migrating species. (I assume that this planet has animals, since you allowed Earth to sub in for the planet in the question, and Earth has animals.) ]
[Question] [ So I've got a species of humanoid giants in the setting. Each individual has their own set of horns, between 1 and 5, that extend from their forehead. The horns determine their adult height, with single-horns generally being 6 feet tall(1.828 meters) and penta-horns generally being 10 feet tall(3.048 meters). Family members tend to have horn counts that are the same among the individuals but sometimes one is born with one less or one more horn nub. The horns are mostly used by the parents to determine and prepare for the sizes of clothes they'll have to make during the growth of their child, but if push comes to shove they are great at impaling things if they can manage it. Now there is some magic in the setting, but being that I want things to exist as independent from magic as possible, I'd like for it that there be an explainable reason as to why specifically their horn count causes such a large variation in height within this species of giants. Is there any sort of natural mechanism that would explain why my giants are taller or shorter depending on how many horns they have? Some extra information, if relevant: * Most of them live in mountainous or snowy regions with the surrounding forest flora being mostly populated by pine trees. Those who travel or live elsewhere exist, but this is their native biome. * Bone density and overall muscle size/strength increases proportionately with height, making each individual not look lanky in any sort of sense unless they were of the skinny sort. * Except for the horns and a slight difference in how their ears and faces look like, they're basically like humans. [Answer] # Growth hormones controlling horn development later control height: It's fairly straightforward. Genetics controls the levels of a growth hormone that is present during development. The relative levels of hormone determine how many horns develop (increasing levels lead to more potential horn sites forming horns). Marry into families with similar numbers of horns, and you'll get offspring with similar numbers. Since it's all relative, some individuals happen to express a little more or less hormone based on developmental or genetic differences. The same hormones are the ones which ultimately determine the upper limit of height in the species. So the number of horns is correlated with the amount of hormone AND the ultimate height the individual is likely to attain. There are likely to be a few rare individuals or families where these two traits become un-linked. So someone could be born with few or no horns, yet still be tall, or conversely have the maximum (or more?) horns yet still be quite short. This would be because of a developmental abnormality that could be genetic or environmental. A certain region might have something that affects traits one way or another. Certain forms of [albinism](https://eyewiki.aao.org/Albinism) result in adults with dark hair and brown eyes, yet they have the abnormal foveal development and vision problems of people with albinism because of the *timing* of the expression of hormones. * If you WANT it to be directly causative, then the hormones can be produced at the sites of the growth cones for the horns. That way, larger numbers of horns result in higher levels of hormone. [Dehorning](https://extension.psu.edu/dehorning-what-are-your-options) would thus end up stunting growth. The genes controlling horn number thus control hormone levels. * Or you could have non-genetic (epigenetic) inheritance control the whole thing this way as well. Mom's hormones control the number of baby's horns, and baby's number of horns control baby's hormone levels. Thus, height is inheritable, but based on the hormone levels of the mother. That way, a female controls baby's ultimate height, and in a matriarchal culture, that way height is consistent throughout the family regardless of who a female reproduces with. [Answer] Genetics is a tricky subject. It isn't like computer programming, where each command has a single definite function. In genetics, stuff can be all mixed together to a greater or lesser degree. If we're talking about [Mendelian genetics](https://en.wikipedia.org/wiki/Mendelian_inheritance), with dominant and recessive genes, if two genes are on seperate chromosomes, the usual rules of gene distribution apply, but if they are on the same chromosome, they are inherited together with a frequency determined by the inverse of the distance between the genes... i.e. the closer on the chromosome, the more often they are inherited together. This is [genetic linkage](https://en.wikipedia.org/wiki/Genetic_linkage). Furthermore, a given gene may determine more than one trait. This is known as [Pleiotropy](https://en.wikipedia.org/wiki/Pleiotropy). So, for the number of horns to be related to height, this may be an example of genetic linkage if there is a strong correlation that is not always the case. Alternatively, if horn number and height always go hand in hand, this would be a case of pleiotropy. Perhaps the genes that code for horns also directly affect height... it could be just that simple, two different sets of tissues affected by the same genes. [Answer] The link between horn count and adult height is just a very strong statistically significant correlation similar to how [blue eyes and alcoholism](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6139948/) are related. ]
[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. To better solicit more inline with what I'm trying to imagine, I'm editing my question, the original question is left below and removing the hard science tag, as that just seemed to cause issues, though I would like to get as close to reality as possible. Reading the site rules this seems the way to proceed, if not I do apologize. Mods do not hesitate to delete. I do appreciate the feedback thus far. The point I wished to get to was any affects a ring shaped object: -spinning from relatively imaginable speeds (%20-30-50 Speed of light) to admittedly ridiculous speed of %99.999 C. -in an area of unoccupied space, outside of any atmosphere but within the orbit of its host star. -The dimensions of the object are at this point arbitrary, But for starters arbitrarily approximately 1 mile diameter(1609.34m), 10ft. (3.048m) thick in all axes, and a rest mass of 500 tones. There have been mentions of [Frame Dragging](https://en.wikipedia.org/wiki/Frame-dragging), which lead me to things like the [Unruh Effect](https://en.wikipedia.org/wiki/Unruh_effect). However I am still unclear and if these would be connected to this device. Further what the visual or detectable effects these phenomenon would exhibit. If external source of light strikes the object, I assume it will reflect blue anti-spinward and red spinward? I find it hard to believe that there would be no other detectable effects of a point of mass spinning near luminal speeds confined to such a small area. Especially quantum effects? Ex: One of the fasted masses ever detected was the "Oh My God" particle. `The Oh-My-God particle (OMG particle) was an ultra-high-energy cosmic ray detected on 15 October 1991 by the Fly's Eye camera in Dugway Proving Ground, Utah, U.S. At that time it was the highest-energy cosmic ray that had ever been observed.[1][2][3] Although higher energy cosmic rays have been detected since then, this particle's energy was unexpected, and called into question theories of that era about the origin and propagation of cosmic rays`. The particle thought to be a proton or neutron would/could this device throw off particles similar to this from impurities in the rings construction? Or from interaction with solar wind or dust particles? collision with micrometeorites? Is it possible for inertial mass to create singularities or singularity like effects? However interesting this is I am more interested in the "I don't know what I don't know, so how do I ask" questions. Which I guess is considered fishing. :( Finally, if anyone is interested, the pretext to this story is this. After sending several fly by probes to a nearly solar system.(Epsilon Eridani) An early colonization ship was sent. on approach even before reaching the planet this anomaly was detected. Picking out a 1 mile wide object from a random point in the solar system requires some justification. And describing the object as they approach will also be a challenge. > > A ring, at this point constructed of perfectly rigid "unobtanium", > and size/mass dependent on what the effects are. For starters > arbitrarily approximately 1 mile diameter, 10 ft thick in all axes, > and a rest mass of 100 tones. > > > What would an observer see and be able to detect in the local area of > space as the ring is spun up to %99.99 C? Would the geometry (height > width thickness) of the right contribute to these effects? Any type > radiation? Warping of spacetime? Gravitational anomalies? At what > point would a ring like this fly apart from centrifugal(?) stress if > constructed of the strongest conceivable material we know of, say > nested carbon nanotubes ~150 gigapascals? Or is some kind of super > science unavoidable to keep the ring together long enough to see > anything interesting? > > > edit this ring is located in space, in an independent stealer orbit. [Answer] You said "near luminal speed", then stated What would an observer see and be able to detect in the local area of space as the ring is spun up to %9.999$c$. I will assume you missed a 9 at the left, for 99.999% of $c$. An observer nearby would see nothing, because they would have their subscription to life cancelled in less time than it takes for the retina to send a signal to the brain. This is similar to [shooting a near light speed projectile in an atmosphere](https://worldbuilding.stackexchange.com/a/107899/21222), although at a larger scale. From the ring's perspective, air molecules are coming at it at light speed. When they collide with the ring the very atoms in the air will undergo atomic fission due to the sheer amount of kinetic energy they will receive. Suppose this rings teleports into some place with an atmosphere while already spinning. If every part of the ring has near luminal linear speed, it is not much different from the ring coming right at us at luminal speed in a straight line. So we have a shock of 100 tons coming at us at 99.999$c$... $E = \frac{mv^2}{2}$, which can be rounded to $\frac{mc^2}{2}$. See where this is headed? It's almost as if you had just teletransported 25 tons of antimatter to a place (which would blow along 25 tons of regular matter, for a total of 50 tons of mass converted into energy). I am not 100% accurate there because I should probably have used relativistic mass, but at this scale it doesn't matter much. Consider that [1 kg of mass, if fully converted to energy, has an output of 21.5 megatons of TNT](https://en.wikipedia.org/wiki/TNT_equivalent). 50 tons would be like one teraton, which is like 25% more boom than Yellowstone's last eruption, or about half the blast from La Garita. [For reference:](https://en.wikipedia.org/wiki/La_Garita_Caldera) > > The area devastated by the La Garita eruption is thought to have covered a significant portion of what is now Colorado. (...) By contrast, the most powerful human-made explosive device ever detonated, the Tsar Bomba, had a yield of 50 megatons, whereas the eruption at La Garita was about 5,000 times more energetic. > > > So we are not talking about end of all life here, but more like having to update a considerable part of Google Maps. At least for the initial impact. What comes next might not bode well to the biosphere. Now we have a persistent problem. You said your ring is indestructible. This means that it won't stop, and after the initial blast it might dig into the crust. It would continuously nuke it, sending debris into the upper atmosphere and space. People very far away would see a huge plasma ball first, thenthe mushroom cloud of a nuke, only it doesn't go away but keeps getting broader and broader as hours and days pass. At some loint, for which I don't have the math, a lot of that debris is going to come back down, heating the atmosphere and cooking living beings in the process. The ground is probably shaking throughout half the planet the whole time too. Please give the ring a stop condition, otherwise this goes on until there is nothing left. --- Alternate scenario: the initial blast sends the ring up. I am quite confident that 2,500 Tsar Bombas under you are more than enough to evict you from Earth with a launch mass of 100 tonnes. The reason being that Apollo 11 had a launch mass of just 28 tonnes but had waaay less punch than 2,500 Tsar Bombas[citation needed], and it made it at least up to the Moon. If your ring escapes the Earth, then life may have a chance. [Answer] Can't help you on what if any relativistic effects you might get from your spinning ring, but I can tell you how to calculate how fast it can spin for any given material. For a spinning ring, it's really fairly simple: multiply the mass of half the ring by the component of its spin gravity that's perpendicular to an arbitrary "cut plane" and you'll have the load on any cross section of the ring (don't divide by two -- there are two supports, but each ring half is supporting the other, so your mass is doubled too). Therefore, if you know both the tensile strength and density of your material, you have half of what you need. The other half is the centripetal acceleration equation: V^2/r (in this case, you have V because you specified it). Hint: make the ring bigger and it'll hold up better, because you're dividing by the radius. So, multiply mass of that half-ring (density \* volume) by centripetal acceleration (distance over squared time) and you get the "weight" of the half-ring. Divide by the strength and you get cross sectional area -- if that's a finite number, this isn't completely impossible for your chosen material. Worth noting that this is a worst-case for strength; the actual "weight" of each ring half will be less than this because most of the spin "gravity" isn't perpendicular to the "cut" plane -- so the actual load will always be less than this naive calculation suggests (and forty years ago, I might have been able to do the calculus to say how much less). [Answer] > > There have been mentions of Frame Dragging > > > I would expect those to be negligible, even if the mass of the object (which would need to be kept together by magic, otherwise it would collapse into a black hole) is substantial. > > Further what the visual or detectable effects these phenomenon would exhibit. > > > It would be extremely bright in all bands, because any material particle coming in contact - and, given its mass, the object would be actively sucking in interplanetary matter and dust - would be annihilated. Any momentary charge asymmetry on the ring's surface would also become a source of electromagnetic radiation. > > If external source of light strikes the object, I assume it will reflect blue anti-spinward and red spinward? > > > Yes, exactly. Except that at those speeds, "blueshift" means that the sun's radiation is reflected back as anything from ultraviolet to hard X-rays. The ship's detector cannot fail to identify it, unless they approach near-axially, and from the spectral distribution it would be obvious that they're looking at a relativistic spinning object. All of the above also means that the ring will require some sort of energy source to keep spinning and replace the energy lost. [Answer] The short answer to your question is: It would look like a white hole. The reason is simple: In Hilbert's In FOUNDATION OF PHYSICS FROM A THEORY OF EVERYTHING TO A CONSTITUENT OF GENERAL RELATIVITY by Hilbert states that particles moving at a little more than half the speed of light would produce an anti-gravity cone. Later Franklin Felber gave a precise solution, 57% of C and you will have a propellant capable of moving almost at the speed of light that will accelerate you slowly but in your case it is more than 99% of the speed of light. The effect would be the same but much more violet, anything trying to approach would be repelled almost instantly except for light which would be extremely deformed in a gravitational lensing effect. What would happen to things like dust or hydrogen atoms in space, I put would become relativistic projectiles. sources: Exact 'antigravity-field' solutions of Einstein's equation: <https://arxiv.org/ftp/arxiv/papers/0803/0803.2864.pdf> Test of relativistic gravity for propulsion at the Large Hadron Collider: <https://arxiv.org/ftp/arxiv/papers/0910/0910.1084.pdf> FOUNDATION OF PHYSICS: FROM A THEORY OF EVERYTHING TO A CONSTITUENT OF GENERAL RELATIVITY: <http://www.bu.edu/cphs/files/2015/04/2007_Renn-Stachel.pdf> ]
[Question] [ Closed. This question is [off-topic](/help/closed-questions). It is not currently accepting answers. --- You are asking questions about a story set in a world instead of about building a world. For more information, see [Why is my question "Too Story Based" and how do I get it opened?](https://worldbuilding.meta.stackexchange.com/q/3300/49). Closed 2 years ago. [Improve this question](/posts/215758/edit) The main story would deal with a strange suicide in a town such as San Francisco in the 30s. The latest case deals with the disappearance of a mother and her child. Each time the bodies are severely damaged, leaving little information for identification and clues for the case. The characters would pursue their investigation, which in the end reveals the presence of a monster in the town. The monster's presence is kept a secret by the chief of police who moves the body each time to a particular location. Now the question, which location serves this purpose ? I thought maybe a railway but drivers could be questioned even if they move town every day. By the seaside, which would feed the Cthulhu atmosphere, but it doesn't explain the mutilation. Bonus point: if you can build a terrifying location known by all inhabitants of the town (bridge of despairs...) The police chief is a member of the cult, he might prefer the most credible approach. Any suggestions. [Answer] # Hidden in the sea is the practical answer. If you want to keep a murder private, you don't want people to know about it. Just dump them in the sea, weighted down by rocks. Simple answer. But that's a bit boring for investigation. # In places where the cop has enemies. A corrupt old cop would likely have friends who helped support them in their reign of terror. They'd also have enemies. As such, businesses which refused to pay the cops protection money could get a mutilated corpse. The beach refuses to pay their protection fee? They get a corpse for all the tourists to see. The bakery decides there's no danger in the town worth protection money? There's the danger of a corpse shoved in their oven. This lets them blame the murder on other things like criminals or a gang, and it works to help them get paid more protection money from businesses afraid to have a mutilated corpse dumped on them. It also lets you vary the mutilations in interesting ways. The bakery might have someone stuffed to breaking point with cakes, the beach might have someone whose flesh was torn apart by fish. [Answer] ## Steep, Flood Prone Ravine You want somewhere that could be a realistic suicide location that a crooked cop could also use to dump bodies. And ideally, the bodies would end up mutilated, to mask damage done to the murder victims. Go with a steep ravine. Ravines are often dry, and prone to flash floods when heavy rains occur. The rushing water is going to do a number on any body in the ravine, and if there's a location with a large drop that's near the road, that could conceivably be a local suicide spot. The crooked cop would dump his bodies upstream of the suicide spot, and the water would push it downstream where it could be found later. The "spooky spot" could be a place where the bodies tend to accumulate, like a place where the walls of the ravine open up, and the water pressure drops. Modern flood management has tries to eliminate this kind of feature in urban / suburban areas, since they are dangerous. But in the 1930s they'd be more common. [Answer] Lake Merced. [![lake merced](https://i.stack.imgur.com/6k4oR.jpg)](https://i.stack.imgur.com/6k4oR.jpg) <https://sfrecpark.org/Facilities/Facility/Details/Lake-Merced-Trail-58> It is in San Francisco. That picture sure does not look like it is San Francisco. It would not take much to make it pretty creepy. <https://sfist.com/2015/01/12/mysterious_dead_body_fished_out_of/> > > Two kayakers made a gruesome discovery while out on the waters of San > Francisco's Lake Merced on Saturday: a decomposing body, face down in > the north end of the lake. KPIX reports that it's believed that the > body is male. However, the > San Francisco Medical Examiner couldn't confirm gender, age, or any > other details to SFist at publication time, saying the deceased had > yet to be identified. > > > The cause of death also remains unclear, the Medical Examiner's office > said today. > > > Lake Merced has long been known as a place where bodies tend to > appear, as a 1910 San Francisco Call story illustrates. Most recently, > a missing Daly City man was found in its waters, and kayakers found > another body in the eastern reeds in 2009. > > > This recent body and the 1910 body were hard to identify. They had decomposed. I could imagine a Lovecraftian monster that accelerated decomposition. I could imagine something that lives in the lake. ]
[Question] [ Assuming a floating island is built from plastic trash or barrels how big would it have to be for motion sickness to become irrelevant? [Answer] Motion sickness is a lot like sex: size does not really matter, and what ruins your experience is unmet expectations. [So says Wikipedia:](https://en.wikipedia.org/wiki/Motion_sickness) > > Motion sickness occurs due to a difference between actual and expected motion. > > > Standing on a floating island might be a lot like standing on the top of a mountain. If the island is stationary or feels stationary, people on it will not feel sick. I have motion sickness and rollercoasters suck to me. Being inside an airplane, though, is ok because for most of the trip they seem stationary. I know they are moving at hundreds of km/h (or mph, at this scale it doesn't matter), but except for turbulences and the food, it's a quite enjoyable experience. I am also ok on boats and ships of all sizes, even when the sea is not calm... Jet skis suck to me, though. Those trigger my motion sickness, even though they don't accelerate as much as an airplane. Maybe because the water and waves feel so close. So I say that unless your floating island is a small piece of rock no larger than a car, people on it should be fine. [Answer] * Must be rigid - otherwise this happens [![if not rigid](https://i.stack.imgur.com/fpT6X.png)](https://i.stack.imgur.com/fpT6X.png) * Must be longer/wider than at least the longest wave-length of the sea waves. If it shorter on the transversal to the wave direction, this happens [![shorter than wavelen](https://i.stack.imgur.com/0OfYr.png)](https://i.stack.imgur.com/0OfYr.png) * If at about the same wave-length, it will need [ship stabilizers](https://en.wikipedia.org/wiki/Stabilizer_(ship)). Either increasing the momentum of inertia to resist rolling around the axis (heavy as hell or using gyroscopes) or active fin stabilizers. Otherwise this happens [![at wave length](https://i.stack.imgur.com/kOFQN.png)](https://i.stack.imgur.com/kOFQN.png) * Your best bet is a rigid structure with the size at twice or more the largest wave length that you are likely to encounter [![twice wave length](https://i.stack.imgur.com/JTHj9.png)](https://i.stack.imgur.com/JTHj9.png) A table in [here](https://en.wikipedia.org/wiki/Wind_wave#Formation) lists the average wave-length in strong wind conditions (92 km/h) to a value of 212m. So you'll need a rigid island about 500m across. [Answer] Floating island inhabitants should be anchored I only mention this because you've used science-tags: there is no magic... Like everything else, your island exists because of the laws of nature. If you follow Newton, floating islands could exist with a styrofoam planet under it, or mass can be in low orbit because of large speed.. but that would not count as "floating". Also, how would the atmosphere be contained, without relevant gravity ? Assuming population on these islands is kind of awkward.. Animals, or civilized inhabitants on a floating island will experience the same near zero gravity. The inhabitants would either fly, or be very small, attached to the bottom or the top. Non-flying species remain on the top, anchored to their island, else they float away into space. Inhabitants originating from a planet surface, like humans, would have to take some safety precautions.. and probably won't survive on the island. They need means to return to the surface.. or to their home planet. Some notes on local evolution While the ecology of your island is isolated, there will be no issue with motion sickness. Evolution on the island will avoid motion sickness in the first place. You can't have species wiggling and vomiting all the time, instead of searching for food. Also, the low gravity circumstances will cause any species to be very small. Species able to fly will have a big advantage over other species bound to the island. I do not know, what conditions would cause birds or insects to experience motion sickness. Motion sickness is something that occurs in mammals used to the ground, when their [sense of balance](https://en.wikipedia.org/wiki/Sense_of_balance) becomes disturbed. Even if afflicted by motion sickness, perceived movement will be too slow The cause of motion sickness is resonance. This resonance results from atmospheric density, winds, size, and gravity. I leave stability issues to Adrian and the other answers, but considering very low-gravity circumstances, I don't expect strong motion, like a ship on a stormy sea. A strong wind would require a heavy atmosphere and it can blow the island apart. Resonance frequencies in such circumstances will become very low, as a result the motion experienced would also be very slow. I enclose the pendulum frequency formula, as you see having low G will increase the period of oscillation T, [![enter image description here](https://i.stack.imgur.com/4CaMr.png)](https://i.stack.imgur.com/4CaMr.png) [Answer] I've seen a sailor get motion sickness from standing on the solid concrete dock, which just proves that motion sickness is an incredibly subjective thing. Personally, I have gotten motion sickness from sitting at a table on the 75th floor of a skyscraper, that was apparently very gently swaying in the wind. I have also stood (clung desperately) to the deck of a fishing trawler in Scale 8 waves (30-50ft waves!!), with no motion sickness at all. It is hugely subjective and situational. [Answer] Your island will have motion sickness, period. To avoid motion sickness you need your object to be large enough that waves average out. The problem is your island is made of weak materials, it can't take the forces that would cause. Thus your island is going to have to flex with the waves and can't shield you from motion sickness. ]
[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/214541/edit). Closed 2 years ago. [Improve this question](/posts/214541/edit) Monsters are creatures mutated by Chaos Energy, which is the driving force behind "magic" in my setting. However, humans were also changed by Chaos Energy; mysterious beings called Kanyeri saved them from insanity and deformation by harmonizing the Chaos Energy inside them with their very souls, resulting in Classes and Adventurers. Like attracts like, so monsters prey almost exclusively on other monsters, as well as humans, especially Adventurers. Why? They encounter Adventurers more often, they're more chaotic (which makes them more attractive to monsters)...oh, there is one more thing. Due to their ties to Alendyias (my Chaos-infused setting) and the Abyss (a realm connected to Alendyias), adventurers respawn. When they die, magic pulls their spirit into the Abyss, where Void energy enables them to form a new body. Once this is accomplished (which takes at most half a day), the Adventurer is brought back to Alendyias, to a safe spot close to or on top of where they already died. Their magical bond weakens with each Respawning, so most adventurers can only do it twice, but some can do it five or (supposedly) even ten times. The thing is, "safe spot for respawning" means "if you land there you won't die because of it." So you won't respawn onto or into lava, pit traps, or pools of toxic sludge, but adventurers can and do find themselves respawning near the monster that killed them, as if a nearby monster doesn't count toward how safe a spawning point is! To sum up: Monsters sense and prey almost exclusively on other monsters because 'like attracts like,' or because Chaos Energy attracts Chaos Energy. Being infused with the same, Adventurers attract monsters, which can be convenient or annoying and dangerous. Because of this, while also taking into account [Chaos Sense](https://worldbuilding.stackexchange.com/questions/213594/impact-of-chaos-sense) and the fact adventurers can 'respawn' 2-5 times (usually two times), forming a new body after death and reappearing in a safe spot close to where they died, it seems monsters will adapt to Adventurers respawning, so my question is: How Would Monsters Adapt to Respawning Adventurers? Specifically, I'm asking: 1. Whether monsters would end up staying to fight or flee from adventurers when they respawn (because if an adventurer dies, chances are they're winning and/or have the advantage thanks to the respawn) 2. Whether predatory monsters would evolve to take advantage of respawning for extra food (adventurers respawn with their gear, including their [Bag](https://worldbuilding.stackexchange.com/questions/197586/are-these-adventurers-bags-unbalanced), but Adventurers can't Equip items if restrained so...) 3. How this would affect a monster's chances of preying or attempting to prey on adventurers (as in the typical DnD-style adventurer, with magic weapons and unusually high power levels). Monsters range from oddities like [Chompers](https://worldbuilding.stackexchange.com/questions/197028/how-can-i-protect-medieval-villages-from-chompers) (which I came up with myself) to typical staples like dragons, giant spiders, and goblins. [Answer] # A Few thoughts: I can think of a few implications that can still work for basic hunters with chaos-powered instincts. * Well, it's golden for spiders , who drag the nearly dead adventurers into their web. Pretty good for monsters able to paralyze, as they can drag prey to a vulnerable spot (giant pit/cenote/dense forest to stop ranged attacks, etc.), kill them, then camp. If the monsters instinctively create "prisons" where multiple small cells are available for adventurers to spawn in, even the weakest monsters may be able to engage in adventurer harvesting. * So imagine the equivalent of naked mole rats building tiny subterranean cells in an area where adventurers frequently are killed. Monsters have a symbiotic relationship, so they render the surface uninhabitable (preventing the spawning at ground level) with fire, ice, or whatever magic they have. The mole-rats eat the adventurers who respawn unable to effectively move, and drop the loot on the surface for the big monsters to enjoy. * Do adventurers spawn as a party, or one at a time? If they respawn one at a time, monsters will camp their kill spot and try to overwhelm the adventurers as they spawn. If the monster feels it has better chances than the whole party, they may be even bolder. * Try to have monsters concentrating on killing ONE member of a party, so the rest must stick around in a vulnerable spot waiting for their comrades to respawn. Monsters then have plenty of time to wear down the party with constant harassment and to bring in abundant reinforcements. Naturally, this could be turned around by adventurers who bring "disposable" members along to lure monsters into providing a constant stream of new victims for the party to kill. P.S. * If I follow your previous questions, adventurers can "pick up" abilities from killing monsters. Adventurers rarely need to deal with monsters that have previously killed them. Perhaps monsters can take abilities from killing & eating adventurers! If these stolen abilities have become so intrinsic that adventurers respawn with them, they are intrinsic enough for monsters to steal those themselves. If that ISN'T the case, then perhaps monsters may acquire the adventurer's intrinsic ability to respawn. Turnabout is fair play, so you may find monsters who regularly kill adventurers respawning themselves. [Answer] The adaptions should be very simple. If an adventurer is respawning, then the monster is winning. This can go one of two ways: Either the monster repeatedly kills and eats the adventurer, until it eventually gets bored and wanders off, or the adventurer gradually wears the monster down through attrition. If the latter case occurs often enough, monsters might adapt to flee after killing an adventurer (if they don’t feel well enough to take another fight.) otherwise, the monsters might sit around and wait for the respawn. [Answer] Opening: "How Would Monsters Adapt to Respawning Adventurers?" Minotaurus - dwell in a cave or a labyrinth When magic declines with death, the ideal situation for the monster is to hunt adventurers inside a cave or labyrinth that is unfamiliar to adventurers. To get them inside, the monster can capture the adventurer during battle and drag it in.. then kill off the prey and eat it. With enough adventurers respawning inside the cave, the monster could cease to hunt outside for a while. There will be food inside for a considerable period of time. Of course, the monster will need some intelligence to do that. If it doesn't have the brains to be conditioned to capture adventurers, it will need the adventurer to enter the cave voluntarily. If that does not happen, I don't expect the monster can do this trick. It will kill and eat adventurers at random, anywhere in the open.. and because adventurers return safe (after half a day.. out of sight) a monster will probably not meet the same prey twice. [Answer] Monsters would learn to live in larger dwellings, large enough that most of "near where the adventurer died" is inside of their fortifiable walls. One the adventurer is dead, the monster would go to every window and portal in their lair and lock them all securely. Then, depending on the threat level of the soon to be reincarnated adventurer, the monster might invite some friends (other monsters) over to share the feast. Adventurers in your world are like a 2 for 1 pizza deal with free staggered delivery. The first meal arrives without warning but after you're done eating it, you have plenty of time to organize a party to share the free second course. ]
[Question] [ There's this reasonably common concept in vampire fiction when the vampires are open members of society: oftentimes there are these businesses where vampires pay to drink blood straight from humans' bodies. The reasons for this generally vary between "the blood doesn't keep well and is tastiest/healthiest when fresh" to "it's just more fun that way", but for the purposes of this question the particular reason doesn't matter. What I'm curious about is whether or not the logistics would be realistic if you made a business, whether it be a restaurant or some kind of "Uber Eats" home delivery thing, that makes its money hiring humans to consensually and non-lethally get their blood drunk by paying vampires. Because on the surface it seems like a pretty daunting undertaking. Humans can only healthily donate a pint of blood approximately once every two months. Assuming a vampire's daily blood needs aren't significantly beneath that, that would mean that for every customer the service can cater to in one night, they would need a rotating staff of sixty part-time employees who would really be stretching the concept of "part-time" to breaking point, because they'd each only come in for one night of work at the business every two months. But despite only working for the company as an extra side-thing once every two months for a little extra cash, each of those employees would have to get proper employee training, and they'd probably also need refresher courses given how infrequently they'll be getting practice. That seems like a lot of overhead for a very big workforce. Could a company realistically make money if it has to maintain an ultra-part-time workforce of 60 people for every one customer they get a night? [Answer] The American Red Cross recommend that you should wait 8 weeks between blood donations. This is to prevent developing anemia. You can lose more blood and more often than that, but doing this often for long term will develop severe health effects. Now, if you have a professional "blood bag" you are probably taking action to staying healthy, working out and taking supplements and drugs to keep your blood count high and stave off anemia. in this way, the professional "blood bag" can charge a premium for their blood. There is also an issue with soft tissue damage at the drain site and possibility of infection. Frequent donators would need some kind of medical maintenance to stay in the business, requiring a high price tag. With this, I cannot imagine a provider could donate more than once every other week, even with maintaining a high quality blood system, but that would be really pushing it and you wouldnt be able to stay in the business for long. But if you are charging $5000 a hit, then it may be worth it to some. Now, as L.Dutch answered, it all depends on your clientele. If you have some vampires just looking for a quick blood fix, stopping into some "fast blood restaurant" you can pay a bunch of crack heads 10 dollars a pop and charge the vampire $50 for a tasty treat. A more refined customer, looking for some quality blood, maybe hit up their favorite provider, then they would be paying top dollar for a gourmet meal. Basically, you can look at the prostitution industry on how to charge clients. Anyone can get services for 20 dollars, but if you are looking for quality service, you could be charging $5000 for it. See <https://en.wikipedia.org/wiki/Eliot_Spitzer_prostitution_scandal> for what some people would pay for services. [Answer] It all depends on the target customers. In the same way as you can't eat fresh lobsters, wagyu or caviar for 1 \$, I assume that using the services of this restaurant won't be cheap, which incidentally also matches with the common depiction of vampires as belonging to the well off. At the end the choice is between paying good money for a clean eating, or venturing in the streets for a cheaper and more riskier meal. If the customer can afford to pay enough, it's totally possible that the paid amount can be enough for a pool of 60 employees dedicated to him/her. [Answer] Yes they can make money. They just have to do certain things: * Be "smart" with how they get people on the table. * Charge the vampires enough to get money. * Provide an overall experience. I'd also add Restaurants by default provide a "extra" service. You are not just paying for the price of the food. You are paying for the quality of food, the atmosphere, the service...etc. Meaning we already have restaurants catering to certain paying customers that are willing to just throw money away. We also have cheaper alternatives that maybe offer you the chance to get the kids to play away from you in peace for an hour. Or others that that just put good cheap food on your plate and be done with it. So. It's all about what they provide. High class establishments would be a thing for vampires as they are for humans. The quality of the "product" is meaningless in a since. If you do the whole experience right, they can suck on grade C blood and be happier than if they sucked on grade A blood from a stranger down the street. Smart business Why bother trying to go the old fashion way in providing human cattle that is practically drugged all the time while the world is full to the brim with blood regenerating providers? That's just stupid. Streamline the process. You have any idea how many teenagers, college kids, working parents...etc would be willing to get paid for blood donation? You have any idea how easy it would be to handle the whole thing with geolocation services, cellphones, waiting lists...etc? Basically create a system designed to save money and time and just make it easier. I will put that in points since I think it might get out of hand * First create a library of providers. Don't want a greedy person donating twice in a week, dying. Then you getting hit with a law suit. * Simple 1 page instructions on how they should act when the vampire sucks their blood. Optional explaining to first timers. Regular providers already know what is going on. Meaning less time * Also you can use mild drugs or alcohol to help if they are nervous. * Build a nice waiting area. Console, tv, kids playing area, books...etc. * Have a point program for the exceptional providers. Those who stay off say smoking or drugs or whatever spoils the blood. Then insures you care loyal providers who are going to continually provide you with good blood. * Entice them with more. It's not exactly fictional that it should be clear that the powerful vampire could take a liking to a particular provider an take them as a...I dunno what to call it. But basically keep it there. That just means that your providers are actually eager to be presentable and happy. The promise of wealth or larger prizes is no joke. * Worried about privacy or something? Put them in mask, have a camera atop the table and record the process. Should limit the claims of rape or missing body parts. * The number of vampire in any given area should be nothing compared to humans. Even on daily feeding you have more than enough people for them to naturally regenerate the blood. * Also vampires are not going out to eat all the time. You get a small amount of vampire who are in smaller than numbers, then from the group fewer would eat, and fewer would take the more expensive features. Experience Chances are you get vampires there on business who are only interested in coffee or drinks. Maybe others are just there for a snack and will take the "cheap" blood bags. Again you are not just serving 1 type of people. Provide variety to cater to all types of vampires that go to your establishment. Maybe there is music and singing? Gambling machines? Whatever. You should not just focus on one thing. Heck. I'm sure you gonna get vampires that might prefer blood bags or even animal blood. In conclusion that sort of thing never stops a business. Don't even wanna talk about darker stuff like human trafficking or stuff like that. [Answer] If you take the "banned drugs" illegal trade like a example...Yes you can make lots of money. Just keep it illegal. But if you are looking after legal affordable price trade, it is like some people told before me, this will be costly impossible. Human blood needs live humans who want give the blood or by piety or by money. How good is the relationship between humans and vamps? Is it like the relationship between healthy humans and hemophiliac humans? Healthy humans donate blood to hemophiliac humans naturally. ]
[Question] [ I am world-building an adventure for the Alien RPG. As a world approaches being tidally locked, and by this, I mean in the process of slowing down, but not stable. In such a world that no longer completes a rotation on it's own axis (apart from that induced by being tidally locked rotation), is it possible to have a partial turn, oscillating back and forth on it's own axis? I picture the characters view from their location as being able to watch the sun come up, rise to about midday, then appear to rotate back towards the direction of "sunrise", to become sunset. I hope I am describing this clearly enough. Is there a way for this to take days instead of months in the process, but not sure what to call this type of action. I am not sure how fast I could have this oscillation occur, either. I picture an Earth-size rocky world as the planet in question. [Answer] TL;DR: probably not. > > In such a world that no longer completes a rotation on it's own axis (apart from that induced by being tidally locked rotation), is it possible to have a partial turn, oscillating back and forth on it's own axis? > > > Nope. This would involve slowing the planet's rotation to a stop, and speeding it back up again. There's a lot of energy stored up in a rotating planet, and trying to stop it promptly will involve some Really Interesting things happening, and those are the sorts of things that you want to be viewing from high orbit. > > I picture the characters view from their location as being able to watch the sun come up, rise to about midday, then appear to rotate back towards the direction of "sunrise", to become sunset. > > > I believe it is possible to get this sort of effect over the length of a day on a tidally locked (or near tidally locked) world, due to the phenomenon of [libration](https://en.wikipedia.org/wiki/Libration#Physical_libration) There's a nice gif of this effect on wikipedia, showing libration of the moon as seen from Earth: [![Lunar libration](https://i.stack.imgur.com/MsCJV.gif)](https://i.stack.imgur.com/MsCJV.gif) You can see an apparent rocking back-and forth and "breathing" motion... the motion isn't the moon really rocking, but slight tilts and eccentricities in the orbit mean that during rotation slightly different parts of the surface are visible from Earth. The reverse is also true. On the moon this would manifest on certain portions of the surface (around the [terminator](https://en.wikipedia.org/wiki/Terminator_(solar)#Lunar_terminator)) as the Earth rising above the horizon, describing part of an [analemma](https://en.wikipedia.org/wiki/Analemma) which might indeed involve an apparent backwards movement at some periods, from some positions. > > Is there a way for this to take days instead of months in the process, but not sure what to call this type of action. I am not sure how fast I could have this oscillation occur, either. I picture an Earth-size rocky world as the planet in question. > > > Unfortunately the libration effects occur over an entire orbit, ie. over the whole year. On the moon they take about a month. On a gas giant moon the might occur over a few days... there are obviously other issues with gas giant moons, and by the time your peeps visit them they'll be long tidally locked. There are plenty of other questions and answers on here about exomoons so I won't duplicate them. If you do go thus route, consider that it isn't necessarily stable for the long term as tidal effects will act to circularise the orbit which will reduce libration effects. This is important for gas giant moons... in order to induce a reasonable eccentricity for interesting libration effects you'll need to arrange an [orbital resonance](https://en.wikipedia.org/wiki/Io_(moon)#Orbit_and_rotation) which has its own problems as Io's exciting geology will show. If you had a smaller, cooler primary you might be able to find just the right combination of habitable zone and tidal-locking timescales for your needs. Suitable large outer planets might be able to give the orbit of your world the eccentricity it needs, but there's a risk of ending up with a spin-orbit resonance of the sort that Mercury has... the day length is 2/3rds of the year length, and the situation is reasonably stable. I'm not sure what libration would look like there. There's a good chance you're out of luck, but the situation isn't so implausible that you couldn't handwave it in. [Answer] You either have two possibilities: 1. the planet is approaching tidal lock from revolving around its axis in a shorter time than it takes to complete an orbit around its star. The tidal forces are slowing down the rotation of the planet around its axis. 2. the planet is approaching tidal lock from revolving around its axis in a longer time than it takes to complete an orbit around its star. The tidal forces are accelerating the rotation of the planet around its axis. You can't switch between 1 and 2, since the tidally induced momentum will become smaller and smaller the more you approach tidal locking, so you won't have an "overshoot". A case similar to 2 happens with [Mercury](https://en.wikipedia.org/wiki/Mercury_(planet)) > > Mercury rotates in a way that is unique in the Solar System. It is tidally locked with the Sun in a 3:2 spin–orbit resonance, meaning that relative to the fixed stars, it rotates on its axis exactly three times for every two revolutions it makes around the Sun. As seen from the Sun, in a frame of reference that rotates with the orbital motion, it appears to rotate only once every two Mercurian years. An observer on Mercury would therefore see only one day every two Mercurian years. > > > [Answer] Doubtful. You say Earth-sized planet and the Earth weighs ~6 x 10^21 tons. * To get that sort of [pendulum motion](https://en.wikipedia.org/wiki/Pendulum#Period_of_oscillation), the planet would need have a mass distribution sufficiently asymmetrical to act as a pendulum and the masses involved are so stupendous that the gravity of the pendulum-like planet would cause it to crush itself back into a rough sphere. * Even if the planet held its shape, the momentum involved for that much mass is equally stupendous and the force of gravity by the central star is only 0.0006 Gs at 1 AU. Even without doing the math, the oscillation cycle would be something on the order of hundreds of thousands of years (at least!) rather than months, let alone days. The sort of gravity necessary to cause oscillation even on a scale of centuries would probably simply tear the planet into an asteroid belt. [Answer] Something similar to this happens on earth near the poles. [![solstice in alaska](https://i.stack.imgur.com/DIZsZ.jpg)](https://i.stack.imgur.com/DIZsZ.jpg) <https://news.uaf.edu/time-stands-still-on-winter-solstice/> In temperate regions we are used to seeing the sun traverse the sky east to west. In the polar winter, the sun peeks up out of the east, rises, and then "turns around" and goes back down, still in the east. If you want your characters to see a sun doing as you describe you need a planet with an axial tilt as ours has. Day length will of course depend on how fast your planet is rotating. ]
[Question] [ I know that congenital insensitivity to pain exists and is autosomal recessive. There is a village in Sweden where 40 cases of this rare genetic disease were reported. I am writing a story with a strange genetic disease called congenital insensitivity to itch. In my story, congenital insensitivity to itch is common in a village inhabited by 600 humans: 30 of them have it. So, I wonder if my genetic disease is possible or a total fiction. What would be congenital insensitivity to itch's mode of inheritance: autosomal dominant (like Marfan syndrome), autosomal recessive (like cartilage-hair hypoplasia), X-linked dominant (like X-linked pituitary gigantism), or X-linked recessive (like Hunter syndrome)? If this is autosomal, what chromosome is linked? Chromosome 1 (like Hutchinson-Guilford progeria), chromosome 2 (like Ehlers-Danlos syndrome), chromosome 3 (like retinitis pigmentosa), chromosome 4 (like achondroplasia), chromosome 5 (like Sotos syndrome), chromosome 6 (like hemochromatosis), chromosome 7 (like tritanopia), chromosome 8 (like Werner syndrome), chromosome 9 (like cartilage-hair hypoplasia), chromosome 10 (like type 2 multiple endocrine hyperplasia), chromosome 11 (like sickle-cell anaemia), chromosome 12 (like phenylketonuria), chromosome 13 (like Wilson disease), chromosome 14 (like Krabbe disease), chromosome 15 (like Marfan syndrome), chromosome 16 (like Morquio syndrome), chromosome 17 (like type 1 neurofibromatosis), chromosome 18 (like type-C Niemann-Pick disease), chromosome 19 (like Donohue syndrome), chromosome 20 (like adenosine deaminase deficiency), chromosome 21 (like autoimmune polyendrocrinopathy-candidiasis-ectodermal-dystrophy), or chromosome 22 (like type 2 neurofibromatosis)? I know I made an extremely long enumeration because the vast majority of the human genome is nuclear and autosomal, sorry. [Answer] Sure. A different NTRK mutation could lose itch but keep pain. [Nerve growth factor, pain, itch and inflammation: lessons from congenital insensitivity to pain with anhidrosis](https://pubmed.ncbi.nlm.nih.gov/20977328/) > > Congenital insensitivity to pain with anhidrosis is a genetic disorder > due to loss-of-function mutations in the NTRK1 gene encoding TrkA, a > receptor tyrosine kinase for NGF. Since patients with congenital > insensitivity to pain with anhidrosis lack NGF-dependent unmyelinated > (C-) and thinly myelinated (Aδ-) fibers, and their dermal sweat glands > are without innervation, they exhibit no pain, itch, signs of > neurogenic inflammation or sympathetic skin responses. > > > This syndrome (CIPA syndrome) is a loss of function in TRKa which is a factor that promotes growth of certain kinds of nerves. It is autosomally recessive. Persons with a mutant TRKa have no pain and also no itch and are generally developmentally disabled. [A described case](https://pubmed.ncbi.nlm.nih.gov/22032467/) has no pain but did have itch (and normal mental function) and had a different mutation in TRKa. If you want it to be realistic, you could just use people with CIPA. Or you could have people that carry a different loss of function mutation in TRKa that affects itch more and pain + sweating less; the inverse of the mentally normal case linked above. There are lots of double recessive people because of inbreeding in this small town. If you are ok with less realism you could have a gain of function of TRKa. They have pain (lots) and sweat (lots) and maybe they perceive itch as something different. Maybe it is painful. Or maybe it is perceived as "pleasurable touch", which is a less well investigated component of skin sensory abilities. These folks are heterozygotes and so no need for consanguity. [Answer] > > So, I wonder if my genetic disease is possible or a total fiction > > > Its hard to say, because [itching isn't perfectly understood](https://en.wikipedia.org/wiki/Itch#Mechanism). There are a few different classes of nerve fibre involved, and it seems to be part of the pain reception system, but full understanding is lacking. It is possible that you could only become truly insensitive to itching if you were also insensitive to pain, and I'm assuming that isn't something you really want. There's a possibility that there are [itch-inducing proteins and receptors on nerve cells that are triggered by them](https://europepmc.org/article/MED/21593341). Whether it is possible to malform either or both of those and suppress or reduce the feeling of itching isn't clear, but there is an avenue of exploration there. Chances are that modifications to the genes which ultimately encode those proteins will also have a bunch of other effects too, though. Few genes are convenient on/off switches for a single system and nothing else. It might be possible to get something similar to being itching insensitive by having some change or damage to the [anterolateral system](https://en.wikipedia.org/wiki/Spinothalamic_tract). This system, amongst other things, deals with identifying where painful stimuli are originating and triggering basic responses, like "put down the hot thing" or "scratch the itchy bit". It is possible to conceive of someone who could feel an itchy sensation and identify it as itchy, but not actually care about it at all and have no scratching responses. > > What would be congenital insensitivity to itch's mode of inheritance > > > Because the exact nature of itching isn't very clear, there's no obvious way to disable it without disabling a bunch of other things and as such the nature of the inheritance pattern associated with genetic insensitivity to itching can't be defined. Pick one you like, that suits your story, and that'll have to do. [Answer] ## It's Plausible and Being Studied [University Hospital of Basel](https://www.sgdv-congress.ch/uploads/attachments/ckrxa7ypu02lk2sjllqcqbo0s-final-poster-case-reports-hsan-sm-9-7-21.pdf) are / have been studying two patients with sensory and autonomic neuropathy. Both are insensitive to pain. They also seem to be insensitive to itch. After a histamine test, most people itch & scratch. These subjects just flatline -- see fig 1 in the link. For your story, I don't think you really need to get into too many details. You might drop a name in dialogue -- "...remember that study University Hospital of Basel did a while back?" But I wouldn't get mired in the neuroscience. Unless you're an actual neurologist! ]
[Question] [ The vehicles are modular, composed of multiple genetically engineered animals with the ability to clip together with specialized structures. The vehicles appear designed with a humanoid size in mind, and the cockpits can be used by humans. The vehicles have their own will (with the brain in the cockpit), but this can be overrided by the controls in the cockpit. There are also vehicles with a large brain in place of a cockpit. These cannot be overrided. A wide variety of tools were made for the vehicles. The society that made this technology is now extinct, and has been for multiple generations of the vehicles What scenario could lead to these vehicles not being discovered until modern times? [Answer] They're elusive, intentionally avoiding humans by observing signs of human activity, sounds, smells, etc. If the population is small enough they could be like certain species of primates, big cats, and sea life which were known for centuries but never formally documented and often written off as legend until a specemin or two could finally be captured by dedicated scientists. Lowland gorillas, snow leopards, giant squids, etc. [Answer] ## They are widely known. Dogs. Cats. Rats. Fish. Monkeys. Everyone knows about them. Everyone has seen them. What they don't know is that certain groups of them can merge to form these vehicles. Through most of history the lack of travel has meant that the right species have rarely met, and the few that exist have hid in remote areas to avoid being hunted down. They have gone down in legends as monsters, dragons, and other terrible creatures. Increasing travel has brought more animals together, and some of them have started to reform these vehicles. [Answer] They live in remote place tops of mountains, middle of deserts, artic, Most of these places were inaccessible until fairly recently. Even if they were discovered would probably be some time before before they figured out that they were designed to clip together. [Answer] They are all deep water animals. These genetically engineered vehicanimals do their thing in the lightless deep ocean, which is where the creatures that built them lived as well. On the rare occasion that decomposition and gas formation brings a dead one to the surface it is no longer recognizable as any specific thing. ]
[Question] [ This question asks for hard science. All answers to this question should be backed up by equations, empirical evidence, scientific papers, other citations, etc. Answers that do not satisfy this requirement might be removed. See [the tag description](/tags/hard-science/info) for more information. I'm trying to figure out what effects would this have on hand. Let's assume that we touch contacts of said capacitor with thumb and index finger of the same (dry and pretty clean) hand (but I'm also interested what would happen for other combination of fingers if it differs significantly). From what I know about supercapacitors, resulting "circuit" will have the following characteristics: * It won't last for long thanks to supercapacitor's ability to discharge very quickly * As a consequence of above, it will also have very high current * Voltage will drop as capacitor gets discharged As for capacitance of supercapacitor, let's say that it's 1 kilofarad (perhaps it's an entire battery of them connected in parallel?), which is quite a lot. It also was charged at 1 kilovolt. I've tried to look up relevant information about this, but almost all sources talk mostly, if not only, about dangers of AC current going through heart, which is a most common scenario in practice but totally inapplicable in my case where DC current goes only through small part of body. Those that talk about other effects of electricity on human body, mention the following additional dangers: * heating * electrolysis I've probably missed some here since, as I said, this seems rather hard to search for (probably a good thing in a deeper sense, honestly). So, what effects on hand/body would this have? [Answer] Normal mains-voltage (240/110 volts) is easily sufficient to cause a shock, that's unpleasant and potentially somewhat dangerous, but because of the resistance of skin which can be anywhere between 5KOhms to several million Ohms, the current flow is usually insufficient to cause any tissue damage. The skin's insulating ability is the body's greatest protection against shock, the standard voltage thought to be sufficient to breakdown the skin's resistance would be [500v](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2763825/#:%7E:text=Go%20to%3A-,Skin%20breakdown,of%20the%20skin%20breaks%20down.&text=This%20lowers%20the%20body%27s%20resistance,flows%20with%20any%20given%20voltage.), now 1000 volts would likely cause fine puncture wounds in the surface (at first, they'd spread fast) which would then allow high currents to flow within the tissues itself causing [tetanic contractions of the muscles](https://en.wikipedia.org/wiki/Tetanic_contraction) (and as it's direct current, a grip you can't let go), heating, [carbonization](https://en.wikipedia.org/wiki/Carbonization) of channels through the flesh and the flow of very large currents, eventually eating away through the flesh creating a crazed fractal pattern: [![enter image description here](https://i.stack.imgur.com/Fln15.png)](https://i.stack.imgur.com/Fln15.png) https://cutthewood.com/ Fair usage 2021. There would be out-gassing as the flesh burned, probable bloating, like the skin on a chicken that gets a gas bubble when you take it out of the oven. Then smoke as the flesh burns. This would take no more than a few seconds. A Kilofarad capacitor charged to 1000v would discharge pretty fast - so the outgasing might be quite dramatic, and you would see the skin glowing orange as it carbonized. [This video illustrates](https://www.youtube.com/watch?v=1jhqZg8UBJU&t=323s), though it's a low current source, the effect on flesh would be faster and more dramatic, and glow brighter (though I've not tried it myself, there'd likely be many small jets of flame-like plasma after the initial steam). The flesh would lose integrity and tendons would detach, or finger joints allowing the hand to be pulled free. There would be lots of permanent damage to flesh, sensory nerves and muscles of the forearm. Speculation: It's possible, maybe just possible, that if the person who's hand touches the electrodes has engaged in lots of manual work and has very thick skin - like a builder or even gymnast, that the skin will be thick enough to prevent breakdown for a while, meaning, if the skin is dry there'd be a painful shock and tetany (and gripping if they were unlucky), but they might get away with little more than a pain memory. If there were gripping, they might have several seconds or even minutes to cut the current/free the hand before the skin did break down (which it would do eventually). [Answer] Capacity matters less than max voltage does As a former electronics hobbyist and electronic component collector, I can say from experience that much smaller capacitors can be quite dangerous, because they are suitable for high voltages. Even with normal consumer elco capacitors, like the the ones used in back in the 60's for TV power supplies. Capacity of these elco's ranged from 100 micro Farad to say, 0.01F for the really big ones, voltage max e.g. 400V. Triodes and Pentodes were involved, that's why they were made for this voltage range. These capacitors could become quite dangerous to handle, when loaded up with the TV's power supply. Supercapacitors work with low voltages In a supercapacitor, which could be 100-200 Farads, you could store lots of Coulombs charge. But generally, the max charge voltage of these components is very small, yielding much lower energy content. High voltages cannot be used, because that would pierce the dielectric surfaces in a supercapacitor. It would be huge size.. or special technology. The discharge voltage would be equal to the charge voltage and as a result, touching the electrodes does not have grave consequences. I can refer to another answer. For supercapacitors, most common is 2.7 Volts. <https://electronics.stackexchange.com/questions/365768/why-arent-there-any-400v-ultracapacitors> Supercapacitors allowing for higher voltages are very rare and expensive. I found below one, it is 130F and it can handle 62.5V. A voltage like that would certainly be felt on the skin, but it will not kill you. And look at the price of this baby.. <https://nl.rs-online.com/web/p/electric-double-layer-capacitors/1797440/> If higher voltages would be allowed, supercapacitors would replace batteries immediately ! They are much more durable than batteries, a capacitor can be charged millions of times, a battery cannot. For backgrounds, <https://www.tecategroup.com/products/ultracapacitors/ultracapacitor-FAQ.php> [Answer] I could say a lot, but if an image is worth a thousand words, then a video is worth a million. [Here is a guy playing with four supercapacitors each rated at 2.6 kilofarads - so 2.6 times over your specs.](https://www.youtube.com/watch?v=EoWMF3VkI6U) ![Soldering a coin with supercapacitors](https://i.stack.imgur.com/8EVgc.jpg) That was a nice coin If you short one of those that is fullly charged, you get some sparks that look like what you get while soldering iron - nice stuff, could severely burn your hand and wrist maybe to 3rd degree, but nothing cinematographic. With four of those in tandem, though... watch as the guy connects those to random stuff, including a circuit board and a dime. Now that's where the fun really begins! ]
[Question] [ Why would warfare become mostly built upon large fortress firing large artillery pieces at other large fortresses? This is somewhat similar to the situation in [R.E.D.C.O.N.](http://www.hexage.net/redcon/). The biggest differences are that this is between 3 nations separated by sea thin enough that [ETC](https://en.wikipedia.org/wiki/Electrothermal-chemical_technology) & [Combustion light-gas gun](https://en.wikipedia.org/wiki/Combustion_light-gas_gun) artillery can fire across it. There is also a small rebellion on the northern peninsula of one of the nations. There are more nations in this world that don't rely on the big fortresses. With these nations having foreign sponsors as well. More information on this world can be found [here](https://docs.google.com/document/d/1xLrHl6icfT14FpSSuX2mmd-86hsw_ukfz87oEb92tWo/edit?usp=sharing). The technology level is near future. Why would warfare degrade to being almost entirely fortress based between these nations? [Answer] ## Maginot Line and North Korea: Fixed defenses are a response to a perceived CLOSE fixed threat. In France, the Maginot line was built because builders thought "We can only get invaded from here" and it might have worked a lot better if Belgium had built its part as well. Similarly, North Korea has one of the most insane sets of fixed defenses along its border with South Korea because the bulk of their likely enemy is in one place, and only likely to be attacked from one place. Fixed defenses are actually pretty great - as long as the enemy can't simply maneuver around them or vaporize them with bigger guns (nukes). So your limited border access is useful in focusing the threat to specific points. The threat has to be constant, so your need for a pretty much permanent defense is worth the cost. There has to be little routine exchange between the countries (think the Berlin wall) because these kind of fixed defenses get in the way of routine commerce. So you need your countries to be close and totally hostile for long periods but not actually fighting, willing to sacrifice trade with each other and not willing to simply kill everyone with nuclear war to dispose of the defenses. [Answer] Geography might provide the answer. If the terrain is very mountainous then it might be impossible to use any sort of fighting vehicles anywhere except mountain passes where they would be sitting ducks to bombardment from remote unseen fortress artillery targeted from numerous hidden local observation posts. Infantry attack might be almost as difficult on exposed steep open slopes with loose scree under foot against well directed artillery and a few machine guns. Other geographical possibilities include swamps, marshes and mud flats overlooked from much higher ground where it is difficult to approach the high ground and impossible to do so without being spotted. Very wide tidally flooded coastal areas could be pose logistical problems for an invading force\. Very flat featureless terrain that runs abruptly into much higher terrain would similarly be very difficult for ground forces to approach as would glacial terrain. Extensive underground defensive positions with multiple camouflaged gun emplacements could be extremely difficult to spot from the air and recon aircraft would themselves be vulnerable to missile attack from the surface. Complex terrain with broken ground, cliffs, bolder fields and ravines could make the situation even worse for the attacker. If sufficient hidden and redundant fire points were built and underground weaponry was mobile in tunnels the situation should be very much in the defenders favor. The defender could simply ignore enemy aircraft and only engage enemy ground forces or could put up a certain limited level of resistance only to increase it to max effort when a ground attack was underway. <https://www.theguardian.com/science/2004/feb/12/thisweekssciencequestions> [Answer] Politicians are in the pocket of artillery makers. The artillery is expensive. Manufacture of ordnance provides good civilian jobs. Politicians like these jobs for people in their district and make sure the government keeps buying artillery. The artillery makers ensure that the politicians benefit from this as well by providing campaign funds and kickbacks. And artillery is good PR. Artillery is spectacular! Politicians can show video of long, manly looking cannons with a subdued and menacing shine. Video of immense explosions that shake the camera. Gaping craters where enemies may once have been before they were converted into gaping craters by the power of artillery. Artillery means you mean business! Neither side is enthusiastic about ending the artillery duel any time soon. On both sides artillery makers, politicians and people are satisfied. Soldiers are satisfied too. Hanging out in bunkers is a lot safer than running around with bayonets. [Answer] Worldwide sanctions In relative terms, artillery isn't effective. Especially in current war scenarios there is little reason to use them. They are inaccurate, don't have the range and do too little damage. Planes and rockets dominate the current warfare. They pack a punch, are difficult to take down and are accurate. Together with combined arms, where you have multiple kinds of armaments that augment each other, you can set up an effective attack. There's only two reasons why artillery is the dominant form. They are somehow more effective & accurate than other forms, or unavailability of the other weapons. Planes and rockets are simply better than artillery, making it unlikely the artillery can truly compete. Mobility, accuracy, firepower and range are all better on planes and rockets. If artillery somehow got better than those, your scenario is unlikely to happen at all. That is why unavailability is your best bet. The world can put sanctions on these countries. They might have the ability to make state of the art artillery and their shells, but the resources for better is unavailable. Without the ability to create, fuel or buy better weapons they might be reduced to artillery and smaller only. Modern fortresses are difficult to destroy without ridiculous firepower or special weapons. The anti-air Fortresses vuild in Berlin are a good testimony to that. Direct hits from bombs and shells in WWII left them practically unharmed. Even when they were stuffed full with explosives to destroy them after the war was met with incredible difficulties, as well as that large parts of the buildings still remained upright even when it did crack. So it is possible, but more likely that even in this scenario the commanders would resort to other tactics. Having Fortresses is nice, but they don't protect more than what's inside. They are immobile and can only deny area, never take it. [Answer] ## Technological counters to stealth, speed and evasion. One of the reasons we don't just use massive fortresses everywhere is that a small group of planes or troops can just take a load of explosives up to them and blow them up cheaply. As such, you need to have tech that makes such things impossible. Advanced visual, IR, and radio scanning techniques that allow the quick detection of any lone enemy and the quick dispensing of artillery or rockets to them which due to advancing in computing are incredibly accurate and dangerous. Anyone foolish enough to have troops in the open will quickly be destroyed by the efficient weaponry of the fortresses be they in the land, sea or air. ## Defense to be better than offense. Stationary defenses have an inherent disadvantage vs mobile forces in that mobile forces can come into range, unleash a load of weapons, and quickly run away. Hit and run can wear them down. To counter this you need a regenerating shield. I would suggest powerful digging engines. Strong generators in the core of fortresses could draw up massive amounts of dirt and stone from under the earth to block any non sustained attack. [Answer] Basically you just need stationary defenses and weapons to hugely outperform anything carried by a person or vehicle. Suppose the fortresses have rail guns with a 20-30 mile range and a 1,000 round per minute rate of fire which is actually sustainable since they are stationary and sitting on a millions of rounds. Well, no combatant or vehicle (autonomous or otherwise) can carry anything with a comparable range or rate of fire, so they get mowed down well in advance of being able to engage. Moreover, defenses that actually provide protection from these weapons are immobile -- whether they are just really thick heavy walls that can't be moved around or something really futuristic like a force field that needs to be hooked up to a stationary power plant. This is almost exactly analogous to trench warfare, wherein you can fling artillery shells and send bullets back and forth, but armies that leave their stationary defenses tend to get mowed down. You just need to amp up the defenses and weapons enough to make the situation plausible with permanent fortress rather than temporary trenches. Edit: rail guns and other technology centered around electromagnetism could be used to explain this technological development in a reasonably plausible way. In addition to the guns, you could pseudo-scientifically explain something like a force field with really powerful electro-magnets. [Answer] ## Trench Lines and Mobile Artillery Trenches are almost synonymous with defensive artillery warfare. With railroads moving the big guns wherever cover would be needed. The only way through would be mobile artillery that could break through the defensive lines. Then your land forces develop around artillery, both defensive and mobile. The Iran-Iraq war saw heavy trench warfare in the modern era. As long as you make it easier to defend than attack by a wide enough margin, artillery will be the go to. Just have good anti-air. [Answer] ## Strong protections to channel attacks I can not emphasize this enough. The only way you can use fortresses as your main protection is if the enemy can't just go around them. Therefore, you need something that will stop people from just maneuvering around. In particular you need protection against aircraft and against ships. An army needs bridges, can be stopped by mountains, etc. An aircraft can fly anywhere. A ship can sail freely. These protections do not have to stem from human effort. If fire dragons ferociously attack airplanes, and sea dragons, ships, that would work. Once you have all attacks channeled, strong fortresses will be an excellent idea because you know where the attack is coming. [Answer] # An Artillery Arms Race I think an artillery arms-race could cause a situation like this. Say, for instance, the nations in question developed both very high-power long-range artillery and high-efficiency short-range artillery very early on. If their short-range artillery was efficient enough (capable of firing accurately and frequently), it'd make it difficult for another nation to get conventional infantry or fighting vehicles close enough to be effective. Once that started happening, the long-range artillery would become much more valuable, as one of the few viable ways to attack the enemy. Its value would demand extremely stout fortifications to protect it against the (presumably) very powerful cross-channel shells. If the nations in question were close enough to each other, I can imagine them falling into a deadlock, where each keeps making advancements in artillery, which requires the others to invest most or all of their research, time, and resources into developing better fortifications and long-range guns. Even if they have ideas for alternative ways to wage war, an intense-enough arms race would leave them with very few opportunities to develop those ideas. And perhaps the nations' workforce, and their research and manufacturing infrastructure, have all been depleted by the war. A bright-eyed young engineer might invent, for instance, a plane that can fly at a high enough altitude to drop bombs from beyond the reach of the short-range artillery. But how would they convince their commanding officer to spend valuable resources that could otherwise be put towards improving fortifications and building bigger artillery shells? ]
[Question] [ A follow up to this [question](https://worldbuilding.stackexchange.com/questions/205376/a-huge-asteroid-is-going-to-hit-how-many-people-can-the-world-put-into-mostly) about an asteroid (which I will give 48 hours before picking an answer). Consensus was that I was being way too optimistic, and that only a small population will survive at best, even in the near future where a closed system is possible, because of the short warning and sheer logistics involved. New Scenario: About a month into government plans to shelter everyone, people realize that it was just a smokescreen and that it was just lip service. Riots break out all over the world, and most are violently suppressed. Most countries go into martial law lock down and dissatisfaction is at an all time high. Question: Would countries, having their hands full suppressing their own populations already, go to war with another country? Are there any countries that might try and fight the United States (and vice versa)? Bonus: If warfare will happen, how big would the scale be, and would it escalate into nuclear warfare? On one hand, the general armies has nothing left to lose. On the other hand, the national leaders would prefer not to be nuked since they have a chance to survive the meteor in a shelter. [Answer] Almost certainly North Korea might suppress the information of the impending doom. Some shelters with long lasting stores have been made for a select few of the elite. Now is the time to settle old scores and possibly get some more resources into the country for rebuilding after. As the USA is likely in turmoil, an egocentric culture based on a dream of having it all, combined with widespread weapons and people still trying to survive somehow, it is an easy target. Don't get me wrong, it is still likely suicide because of the minuteman nuclear silos of which some might still be functional. Though they also represent the safety the masses are looking for as underground bunkers. Yet with the world ending, you might as well just show your power and go into your bunkers a bit earlier. Other countries might do the same, if some cohesion can be found. Nationalism or a strong sense of community and culture. China and Japan are likely candidates, allowing them to quickly spread and retrieve many resources in the hope they can use it later. Even if large parts of the system is failing, many facets of the military might still work because of the sense of duty. Most likely all conflict reasons are thrown out and any country will be sacked as long as it's not some of their own people. [Answer] If there was only 5 months before a devastating asteroid strike, I would imagine that the prospect of any major conflict breaking out is not huge. Each nation's military assets will probably have their hands full trying to maintain some semblance of order internally, and it would make much more sense to preserve as many military assets to defend what scarce resources remain should their nation survive the asteroid strike. For major powers like the US, China and Russia, there wouldn't be much to gain from any war with either their neighbours or another major power. Most of them have enough domestic resource production such that their efforts would probably be on stockpiling oil, food and machinery, and trying to prepare as best as possible. Trying to defeat a strategic rival 5 months before they are likely obliterated by an asteroid would seem somewhat redundant. By the time it takes to plan, mobilise, fight a war and then consolidate any gains, you won't have much time to make use of any land or resources taken as one would imagine much of it will be devastated by the asteroid. For minor powers in the Middle East and North Africa, for example, if their neighbours are too distracted by internal turmoil to properly defend oil fields, arable farmland etc, you could expect some border clashes as they annex certain regions in attempt to stockpile as much as they can. As international trade will likely take a big hit in this period, if they are able to seize resources with little resistance this may put them in a better position to survive. However, being drawn in to a major conflict is the last thing they would need, using up much needed military personnel and fuel, so even modest resistance would make this more effort than it is worth. [Answer] Medium-large scale war with some nuclear strikes? ### YES IT'S POSSIBLE. BEAR WITH ME. A dimensional rift suddenly opens and a 20 km-wide rock of mostly unknown material hurls to hit Earth? "This is exactly as prophesied in [insert a holy book]! God has started the Apocalypse!" Religious group(s), armed with their unwavering faith, quickly seize control amidst the anarchy. They capture the disorganized militaries' facilities and weapons. Then they control the media or whatever's left of it. They absorb the general people into their ranks by promising safety/salvation. "Don't worry, for God will save us the believers!" or "Be strong, together we are able to [do something commanded in holy book that sounds more plausible than bunkering down entire populations], and soon after that God will reopen the dimensional rift right above Earth and send the asteroid back to anywhere it came." Basically, spreading optimism and rallying people together by celestial promise. In hopeless times, religious promises provide the only hope. The group(s) then very soon after wage holy wars. They believe they're the good guys of the Armageddon, the Final War of the World. They want the eternal record to see them as the protagonists of the last act of the universe's theatrical stage. They may or may not declare themselves officially as a country beforehand, but in reality they're comparable to one already. --- From there it's not difficult to imagine United States (or any major world power, give or take) painted as the bad guys in their perspective. Modern imperialism, extracting world resources to be enjoyed by the few ultra-rich; capitalism, putting property above life/modesty/decency/humanity; secularism, separating official national matters from the obligation to follow ways of life; too much liberty that all conservative religious laws were removed/changed/adapted; oppression and/or unjust neighborly treatment; racial motivations; etc. Nuclear war? Well, does the group originate from nuclear state? I'm not sure on can they acquire nuclear weapons and how much. But, their immense faith may justify a nuclear first-strike to destroy their enemy, if one is available. Second-strike retaliation may happen, but I'm not certain. * Possibility 1: Group(s) launch enough nuclear weapons to destroy United States entirely (unlikely? I am speculating it's unlikely). United States fully commit their second-strike. * Possibility 2: Group(s) launch small amount of nuclear weapons (more likely, if they can do it at all). United States basically shrugs off and ignores one or two city being obliterated. World is ending and people will die en masse anyway. Either they fully ignore, or retaliate with also small amount just because they can. No full-scale nuclear war, only limited exchange. [Answer] ## 100%, there will be wars within the first few days tldr; border skirmishes for the best places to survive, civil wars dragging in other nations, and neighbouring countries being attacked by non-standing armies and being forced to invade. Other answers so far have focused on standing armies declaring war officially, but there are many non-official triggers for a full scale war between nations. Here are my predictions. Firstly, a scramble for higher ground will result in border wars, particularly around mountainous areas - consider Afghanistan and Pakistan. There's not a lot of arable land at high altitudes - whatever does exist, will suddenly be highly sought after. Secondly, armed groups not affiliated with governments can start full scale wars between international entities. Rebels from one side attacking the standing army of another, or engaging in terrorist activities, resulting in an invasion. Thirdly, some people will attack their own governments, out of anger, desperation, or because they believe the flying spaghetti monster can be placated if only their government stops building roads and starts building massive statues of the Flying Spaghetti Monster. Substitute this with real, existing religions (I'm not going to mention any). Nearby countries may be forced to act on foreign soil to protect key resources such as oil supplies, ports, etc. This might include "Boots on the ground". [Answer] I'll quibble at the lockdowns in America there are just too many guns, and with the media the way it is (re: watergate) it's possible that the media and the internet is used to stoke a revolution. the leaders should realize that wasting resources here would be bad so that it might be possible that after he knee jerk lock down they make a plea to the populace: what must be preserved after the impact? what should we save as we cannot save? letting the people decide who to save would improve america's chances greatly and by letting people vote with their labor; (remember dollars would be worth nothing quickly in an apocalypse scenario) we can channel everyone's labor toward the preservation of man. then it's a measure on what should resources should be spent on other than bunkers I'd argue for a mechanism to clear the air of he detritus and seed banks. the argument being if we can clear the air fast enough after the impact we worst of the impact will be removed (the blocking of the sun from reaching plants) so to the others what size are the particulates and wat can be done to clear as much of it out of the air as possible? [Answer] Yes there will be war, but not the one imagined. The soldiers understand that the high rank officers want to exploit their role to save themselves and they kill them. Middle rank officers manage to keep together some military units which then turn into uncontrollable armed gangs. Such is the fear and the pressure that it will be easy for a chasmatic leader to take control of a gang and the war quickly turns into a war between warlords. Immediately the new warlords start looking around for supplies and the nearest place that can be turned into a shelter like an abandoned mine. I doesn't matter if what they need is on the other side of the border they try to seize whatever they can. Some of them manage to seize some atomic weapons, but they realize that they are useless, they can't risk to contaminate the place where they should shelter and they cant use the bomb as a threat when everybody has nothing to lose. Legal borders will disappear, government leaders will retire in their own shelters with the few military units that remained under their control. They will try to stave off the pressure from the warlords and the rest of the population by promising that a program to deflect the asteroid is going on. Nobody knows whether it's true, but they'll end up fighting each other and leaving the ex leaders alone. [Answer] I would expect to see religious wars. I'm not going to make it anyway, why not kill some of my hated enemy before I die? ]
[Question] [ Phemogian are a seven-sexed species that passes gametes in a chain. Each sex can inseminate one other sex and be inseminated by another sex. Each phemogian has three parents, with the last parent in the chain completing the process. What would be a possible sex determination system that could explain this? [Answer] The breeding happen in stages between specific sets of the species The genetic structure of this species is very complicated, even so complicated that the base building blocks are not possible to build by only two of their kind. You only have one birthing sex while the other sexes are intermediate stages. To fit that only 3 sexes are required I would suggest a pyramid scheme. [![Genetic passage tree](https://i.stack.imgur.com/HOgQx.png)](https://i.stack.imgur.com/HOgQx.png) So you have sexes A,B,C,X,Y,Z and F where F is the only species given actual birth. Sex A only has sex with sex C, sex C has sex with F, and so on. Sex C and Z are intermediate stages who will not give birth, only F gives birth. So what happens when to sexes come together. So if sex A has sex with sex C, (sorry lot of sexs :D) sex A will pass its genetic code to C. C will combine the genetic code into a new gametes type including both the genetics of A and C. Subsequently if C and F procreate it will pass on the genetic code of A as well as its own. Thus sex F will birth a child with the genetic codes of A, C and F included. Do to the complex nature of the genetic code if different sexes try to procreate (even if it is physically possible) the genetics won't match and not gametes will be created to pass on. NOTE: now I structured it as a pyramid but you could also choose for different system. A circle construction comes to mind where each member of the sex needs to have the gametes of both adjacent sexes to be able to create offspring. In this fashion all sexes could birth, or you can have four males and three females. It all comes down to the genetic make up being to complex for two individuals to make up. [Answer] Caste system The creature has a caste system, much like ants. Castes help with specialization of tasks, benefiting the species as a whole. Different from ants though they have grown in different configurations from coupling between individuals, instead of all males with one or a few queen like entities. The specialization doesn't need to be spectacular. Other differences are that they are more like the birds of Darwin. Instead of 7 sexes, they are essentially several species closely related to each other. Each in the chain can procreate with the ones closest to it's own genes, but not further away. Next is why they want to procreate with three species. Two species procreating is advantageous, as it allows for quicker evolution than species that procreate singularly. In addition, the handicap of requiring both the energy to procreate and the requirement of a mate filters out creatures that aren't fit enough in their environment to get both. The requirement of 3 mates can push this further, also reducing genetic defects that can happen naturally or a result of inbreeding. That means with 3 mates you can procreate closer to your family tree with less worry. If you're asking how procreation between three creatures came to be I wouldn't know, but if we can make the jump from mono procreation to a dual procreation, the jump from 2 to 3 individuals in procreation seems a much smaller one. Some creatures like snails are hermaphrodites, having both functional sex organs. Your species can accept genetic material from another, combining it, then passing it on to a third party, who combines it as well. That way all are present can add their genetic material to the egg and it can be grown by one of the individuals. In the end, thanks to environmental genetics and the makeup of the genetic donors, the resulting creature can grow into one of the species, possibly rejecting some other material altogether. Seven sexes I'm having trouble with the seven sexes part. Although I've heard that some fungi have over a thousand sexes, I never have seen any elaboration of how it works and why they are seen as different sexes. The above can approximate different sexes in the same species quite closely and might be an acceptable answer for you. [Answer] [Linear-Feedback Shift Register](https://en.wikipedia.org/wiki/Linear-feedback_shift_register) (aka LFSR) Numbers 3 and 7 may seem a little strange in this context, but, let's not declare an idea impossible before thinking about it for five minutes\. There actually is* a simple way to arrange triplets of items into a seven-step cycle: ![three-bit LFSR](https://i.stack.imgur.com/aER0p.png) That's a queue of three bits, supporting a "shift" operation in which the rightmost bit is discarded and a new bit is pushed in from the left. The new bit depends on two specific bits of the previous state: If they were different the new value will be 1, and vice versa. This produces a sequence of length 7 before the triplets start to repeat (unless you start from "000", which cycles immediately). The complete sequence is left as exercise to the reader (hope the reader will not find that I messed it up). The "bits" could be chromozomes, each of them being either X or Y (just different symbols for 0 and 1). Or maybe DNA strands with a polarity, direction? The LFSR thing, then, is their way to scramble genetic information in order to create some novelty in the offspring. Terestrial organisms [do have such mechanism](https://en.wikipedia.org/wiki/Chromosomal_crossover), which ensures that chromozomes are not just cloned from parents to children, albeit in a new combination; Instead, parts of a chromozome are mixed together, and with help of some smart evolutional engineering they remain viable. In case of phemogians, the "rightmost two" chromozomes are blended to form a new one, whose polarity/XY-ness is determined by the combination (I guess the three chromozomes in a triploid cell do not have an equal status, so it can be defined which ones are the rightmost). This "meiosis" needs to happen three times in order to build three new chromozomes, with some handwavy molecular compatibility involving the "leftmost chromozome" to enforce the LFSR rule. It also probably means that the child sex is fully determined by the combination of parents; So, a Sil, a Trem, and a Kiim can only spawn Jeks. Some remaining questions: Why would evolution bother with this? Seems tricky, but anyway, evolution came up with 13 or [17-year reproduction cycles](https://en.wikipedia.org/wiki/Magicicada_septendecim), so it may have some affection for prime numbers... What about the "000" combination? They may be non-viable (boring). They may bear some Down syndrome. Perhaps they existed once as healthy members of the species, but have separated into a new species once the LFSR law kicked in (it prevents them from interbreeding with the others). They may be the phemogian version of non-binary gender. \And who the hell said the thing with five minutes? Update:* Got in drawing mood today (and calculating): ![Phemogian reproduction cycle](https://i.stack.imgur.com/d1DrA.png) [Answer] ## Individuals are hexaploid, gametes are diploid. Let's call 0 and 1 the possible sexual genes. Then, one individual can be 001011, and produces 00, 10, and 11 gametes. When the first individual inseminates the second one, the gametes recombine and fuse, becoming tetraploid, but it's not enough for an individual: enter the third individual, whose diploid gametes recombine and fuse with the other four, completing the set. The individual's sex will be determined by its 6 sexual genes, grouped in three: A = 000, B = 001, C = 010, D = 011, E = 100, F = 101, G = 110. 7 sexes. Handwave that H = 111 is non-viable. So, each individual's sex is encoded into two letters: BE, FA, CC, and so on. Add a dominance rule to establish what letter(s) dominate others, to determine the sexual fenotype. This should be enough for any 3 individuals to procreate, and still determine the sex of the progeny. [Answer] Divergent genital morphology. Genital shapes evolve quickly and can be engines for speciation. [Divergence in genital morphology may contribute to mechanical reproductive isolation in a millipede](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3586643/) > > Species-rich taxa usually display significant divergence in traits > related to reproduction . This pattern has led to much debate over > whether sexual selection may underlie rapid divergence in sexual > structures and, therefore, be an overlooked “engine of speciation” . > Genitalia are arguably the most variable of all sexual structures, > with striking differences apparent among taxa, including between > closely related species . As with other sexual traits, it is thought > that intense directional sexual selection drives the rapid evolution > of divergent genitalia among isolated populations , potentially > leading to an increased frequency of speciation. The classic > hypothesis for genital evolution posits that genitalia function as > “lock-and-key” structures, which are subject to stabilizing selection, > enforcing mate recognition and species isolation... > > > Your creatures are triploid as you say, with haploid gametes. They are hermaphrodites with structures capable of emitting and receiving spermlike gametes as well as a structure capable of allowing maturation of a completed 3-gamete zygote into an egg or embryo. The restrictions on possible mating partners are simple matter of genital morphology according to a "lock and key" system. The described interactions for each sex are the only ones possible given the genital morphology of the participants. This would mean that artificial inseminations and progeny could be possible between 3 partners for which their genitals would make it biologically impossible. That is the case for some spiders which are different species by virtue of different genital morphologies. Hybrids can be produced via artificial insemination. ]
[Question] [ What my question is really trying to ask, is if it's possible that some alien race possesses technology far more advanced than our own, but also have an interpretation of physical results that is less experimentally accurate and less mathematically consistent? To provide context, I'll give the story explanation for why this is the case. In my story, it is relevant to the plot that there is a galactic regime limited to strictly galactic or inter-stellar travel. They aren't capable of inter-galactic travel, because they are limited to propulsion that is only fast at the inter-stellar level. The reason for this and other limitations, is that their theories of physics can't account for the physics more advanced tech. This is due mostly to their alternative interpretations of quantum mechanics, gravity, and classical laws. The source of this difference, is that their scientific philosophy isn't concerned with how things really are, because this race only ever pursued science to the end of its' practical applications. They never really had a thirst for "knowledge for its' own sake". This got them quite far, but their interpretations lead to explanations that don't account for higher physics. For example, they don't have a theory of quantum gravity, because the problem doesn't exist; they don't have quantum field theory or general relativity, because they have a different explanation for experimental results. The reason their solutions are not our own, yet theirs are both less correct but also more useful, is because they don't have our philosophy of science. They don't care about understanding reality's nature, they care about utility, and so they only measure scientific merit by the concrete, tangible ability to give new technologies, rather than our more abstract criteria. If the theory's physics allow for tech, and the tech works, then its' been validated. If a theory allows more tech, then that's the right one; That's all there is to it. Their interpretations work well enough to give them tech, so they don't question it. On the other hand, QFT, GR, etc, satisfy our more abstract criteria for correctness, but that's very different from a scientific method geared towards utility; Our theories may be more likely to be correct according to well-established philosophical criteria for empirical correctness (the scientific method we came up with), but this species measures by model utility, not model accuracy, and more accurate models are not necessarily more practically (read: "engineering-wise") useful models; Our theories are accepted because they are more accurate based on the criteria for empirical correctness, but while our theories do allow for new wonders of technology, they aren't exactly known for their ability to do so, which their scientific method is based on; This means they would logically dismiss our own ideas. Even if the theory is not as mathematically developed or experimentally accurate, simpler but less accurate models can be more useful in engineering than complicated explanations. Because of this, they did not care about the explanation that best revealed the universe's nature, only what best revealed new technology, and so they never discovered the true ultimate theory. When they realized they couldn't escape the galaxy and couldn't do some other things, they began doing more physics work to reveal technology that would enable this. But, only the universe's nature would reveal such technology, and to find it, they had to solve for another problem; Historically, they had no care for pure mathematics (only applied math, due to their utilitarian views precluding any incentive), which meant that they didn't even have the mathematical concepts required for higher theories. As a result, despite being more advanced technologically, they actually have to catch up with us in the realm of the pure mathematics (i.e., they have no concept of lie-groups or fiber-bundles, and they aren't used to thinking so abstractly). And due to their regime, which is a hard-communism even worse than the soviet union, science doesn't really experience breakthroughs; Only cautious incremental steps. Also due to their regime, alternative knowledge often gets snuffed out, alternative tech rarely gets a chance to flourish, and every other race more advanced was also a predecessor that already went extinct, so their knowledge has been buried in history. However, I'm not quite certain how to explain their ideas in a self-consistent way. So what I want to know, is if there is a case in physics where a theory couldn't be the real case, due to mathematical inconsistency or experimental inaccuracy, but from an engineering point of view the theory was not just more useful, but useful enough to allow technological advancements faster than the more accurate model? I'm also asking if this could be extended so dramatically, that you could get a situation where a theory allows things like warp-drives soon than a more accurate theory, but experimentally or mathematically isn't as close to truth. [Answer] Setting aside that different models have just different approximation level of reality and there is no totally wrong one or totally right one, it's perfectly that case already with the theories we have developed so far. Take the Copernican model of the Universe vs the Ptolemaic model. A civilization using the first one would have no practical advantage against a civilization using the second one, and the outcome of their clash would be determined by other factors, such as weapon development and so on. Again, take the ancient Greeks. For how much non precise was the Aristotelian description of physics, it was surely more advanced than what the Romans had. Nevertheless overall Rome was capable of conquering Greece since it was better at many other technological aspects. Last example: unless you want to use very precise timings like in GPS, relying on Newton or Einstein for a gravitational model of motion on Earth will favor those who go for Newton, because it's way simpler to calculate. Even all the technology that we used in today's devices is based on the physics developed in the first half of the previous century. [Answer] Your aliens stumbled onto a cache left by someone else. They simply know how to use what they have but have no understanding of either how it works or how to replace what they have if something breaks. [Answer] I see 4 ways this could happen: ### The inherited / found / trade their tech. They dont know how to build their own ships because they are not the builders. Perhaps the ships (and training) were delivered as part of a trade deal. This is totally plausible and has real world parallels; Australia cant build an F-35 fighter jet but we've arranged through diplomacy to get a few and some flying lessons. We could do some basic maintenance but we couldnt rebuild more from scratch. ### They regressed after building it / in transit. Your aliens used to be smart. They built fleets of ships using advanced physics and maths. Then they focused on other things. Now a few generations later they've forgotten some of the details of the advanced maths but can still use their tech. ### Earth is real smart but constrained by economics / politics. Rather than dumb down the aliens, let's smarten earth up. Every university prioritizes maths and physics, and we start experimenting and learn so much. We learn how FTL can work in models and simulations, but because the ethics board says no, we then move onto even more exciting physics. The aliens arrive knowing minimal maths and physics required to build ships - we know more theory than they do, we just havent had approval to put any of it into practice yet. ### Physics and maths have whole unknown fields allowing multiple tech paths. Turns out the fields of maths and physics are much vaster than our simple minds can comprehend, and there are multiple perfectly valid paths through both fields that lead to FTL and spaceships, and the tech trees don't intersect. Two races can meet with FTL and share zero physics or maths, despite their own understanding of physics and maths declaring that to be impossible. Teams from both earth and alien sides try to communicate with the other using common knowledge, and obviously start with basic mathematical building blocks - that turn out to not be not so common at all. Our puny minds cant grasp the foreign maths and physics, and their puny minds cant grasp ours. Our scientists sit there going "well obviously they know integers, right? They obviously can count right", whereas their scientists are just scratching their head wondering why we dont understand core mathematical concepts like zzzfff, - a concept so core that all races obviously must understand if they have any tech at all. [Answer] It's an innate physical skill. Imagine that humans encountered a species without eyes. They had developed cameras and every manner of sophisticated AI pattern recognition. If we lost a crewman somewhere on the Moon, we could never look over photos of the entire surface fast enough to find her. But the aliens could run our satellite feed through their systems, churn over the data, and send back coordinates. Then we say "oh look, she's waving at us", but the aliens have nothing but pixels and color changes to talk about and would have taken weeks to try to model out that explanation. Now to take your situation, the aliens are the ones with a physical ability. Maybe they evolved in the upper atmosphere of a star, and they can control (really are) magnetic fields and plasma and can move at great speeds from one star to the next. But they might not really understand electromagnetism - odds are, they may not have ever done those old experiments with amber and fur. Their space drive may be little more than a rowboat made out of plasma, shaped with magnetic fields and maintained and navigated according to traditional tribal practices. There might definitely be a place for earthly efficiency experts to run supercomputer models and help them limit leakage - supposing by then we've figured out how to keep a tokamak running for longer than 20 seconds at a time, that is. [Answer] Go biology instead (with a nod to Harry Harrison's West of Eden) Have them selectively bred organisms (and even themselves) without understanding the micro science behind it. A bird doesn't know calculus or physics to do their intense aerodynamics. (at least we don't think so) Their abstract thinking could be more purposeful rather than explanatory. They need a starship, they grow a starships, need a reactor, grow.... [Answer] ## Flip it and make humans the ones who specialize in practical models Human understanding of physics is already geared far more around practicality than reality. The Scientific Method does not actually care about truth, it just cares about things being repeated often enough to get a less than random pattern. Therefore any theory derived from the Scientific Method that is repeatable will appear true, no matter how false it is. Examples: * Quantum Physics does not actually prove that a thing only exists as a probability, it just tells us that we do not know a thing's exact circumstances so all quantum predictions can only be made as probabilities with the technology we have today. * The Theory Relativity does not actually prove the existence of a thing called space-time, only observational relationships between local motion, relative motion, and the speed of light. * The Bohr Model does not actually tell us what an atom looks like, but it gives us a very practical understanding of it for predicting chemical properties. * Biochemistry does not actually tell us how a person will respond to a certain drug, just tell us a probable outcome. While all 4 of these fields of sciences are either wrong on incomplete, it does not matter because they allow us to get to practical, repeatable outcomes. In contrast, the aliens have already figured out exactly how the universe works... the problem is that the universe is FAR too complex for the aliens to actually understand. Instead of using simple workable models that they can conceptualize, they model reality through computer programs that have been added onto over thousands of years to the point that the aliens no longer understand how the whole program works together. Their top physicists might only understand 1% of what the program does, but that is okay because they work in RnD teams of hundreds of scientists who each understands his own part in making the absolute reality computation system work The reason the aliens can not advance any farther than their current level of technology is because they never simplify things. In human math and science, when we face an [intractable problem](https://en.wikipedia.org/wiki/Computational_complexity_theory#Intractability) we compromise by simplifying our models until they are solvable. We use heuristics, rounding, and optimal stopping to bring us to answers that are usually correct, even when we know there is a tiny chance the answer will be wrong. The questions that the aliens have been up till now unable to answer are all centered around intractable problems. So, when they see a calculation that would take till the cold death of the universe to complete, a human scientist could come along and say "I can solve this correctly 99.9999999% of the time in 5 seconds." The alien says, "but if you are wrong 0.0000001% of the time, you have not solved the problem". So their dedication to absolute truths keeps them from finding workable answers. [Answer] Yes, but not at our current-technological levels(haha) To mildly elaborate, through human history you'll find plenty of instances where one group was more or equivalently developed but outcompeted, concqred, or just shoved into a historically irrelevant corner by the virtue of having superior technological capabilities, without their education being anywhere near as good as the conquered group That being said, they were all, roughly speaking in the grand scheme of things, roughly at the same levels of technological development, consequently the short answer might be yes, but humanity would have to be already spacefaring to a degree (FTL spacefaring)to have a greater level of understanding, or at least have the knowledge to be able to be spacefaring, but aren't for whatever reason. You can't really have it otherwise. ]
[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/201245/edit). Closed 2 years ago. [Improve this question](/posts/201245/edit) I have this planet that is mostly composed of an unknown acid. Lets name this acid, Substance X. However we can survive on this planet with basic rubber suits, as this acid cannot burn through rubber nor metal. The acid is formed when pure oxygen hits a noble gas we will name Substance C. Substance C is heavier than air and is found at the ground. The planet produces an infinite amount of these gasses, and the oxygen comes out of vents in the ground from an unknown source. Many people who have tried to enter these vents are either burned alive or are terminated by asphyxiation. When Substance C is burned at high temperatures, it will explode and then turn into CO2A (A brother to CO2) which then can enable plant life. Note: When Substance C is burned, It explodes in a cyan color before disappearing. Question: How will I be able to land a rocket to inhabit the planet? [Answer] It looks like xenon tetraoxide could be a candidate for your gas. <https://en.wikipedia.org/wiki/Xenon_tetroxide> > > Xenon tetroxide is a chemical compound of xenon and oxygen with > molecular formula XeO4, remarkable for being a relatively stable > compound of a noble gas. It is a yellow crystalline solid that is > stable below −35.9 °C; above that temperature it is very prone to > exploding and decomposing into elemental xenon and oxygen (O2) > > > If you are up to making your world around this exotic chemical that would be cool. Or maybe if your chemistry is not that strong instead of Xe you could use some undiscovered noble gas of higher molecular weight than oganesson so you can assert undiscovered chemostry and not get called out by people who groove on calling out chemistry errors in works of fiction. They are out there, those folks. I could imagine that a descending chemical rocket or a hot thing entering at orbital speeds might set off an explosion of all the accumulated substance C. Two strategies 1: Set it all off in advance. Drop some bombs, then after a minute or two follow them. Good stuff for an anime as the exploding green clouds of flame will be below your falling characters. The bombs will have detonated all available substance C in their path and it will be safe for your people. It might be kind of a mess on the ground after all the upblowing. The substance C will reaccumulate so no smoking once you are down. 2: Glide in easy. You people glide down from orbit, very slowly shedding velocity in their flying squirrel suits. Nice and easy, nice and easy, not stirring things up. It will take a while so they should have onboard music, or radio connection with their peers to play 20 questions. --- thinking about coming down behind the bombs - there will be phenomenal updrafts of hot oxygen and xenon as the XeO4 dissociates. It might do a lot to slow down reentry. [Answer] I don't know about the accuracy of all the other elements in your post, but if the bottom line question is "How will I be able to land a rocket to inhabit the planet?" then you can always land with a parachute. Just turn off the fire before you enter the atmosphere. If your pilots calculate the trajectory just right, free fall will do the rest, and you wont even burn up in entry. Quite a bunch of heavy things have landed from great heights. Military supplies in bulk, returning space capsules (proof that this can be done), even Elephants. And, at least one dude jumped down from space. Now, getting the rocket back up into space... ? This might solve both problems, but its handwavy: If your astronauts are arriving at another planet, then we can assume much higher level of technology than we have now. So how about anti-gravity? They'd know about the acidity and explosiveness (they'd have analyzed with telescopes and sent probes to verify) so they'd be prepared for it. [Answer] Heat shield, parachute and (air) pressure I'm assuming that the rocket can't just land on rocket power due to the burning, or it would render the whole question moot. We can look at current ways of getting people down from orbit. They require a (relatively) gentle deceleration as well as gentle landing. What mostly happens is that a capsule will slam into the atmosphere from orbit, starting to slow it down. The heat shields will absorb/redirect the heat generated from the friction and air compression. Afterwards parachutes are deployed for further descent. Rockets might be used for the correct orientation before parachutes are deployed. Landing in water can be done without breaking rockets, but is still sometimes done for a more smooth landing. Landing on land as far as I can find will always require breaking rockets. If there's already airborne infrastructure on the planet you might capture the capsule mid-air. Now you only need to replace the breaking rockets. Chemical processes have a lot of power, which is why they are used. Still, if you add huge compartments with compressed air/liquid you can potentially get the same results. Just be mindful it'll take a lot more weight and construction, as well as that the propulsion is likely less strong and cannot continue as long. If you only want to land materials then parachutes and heat shields can be enough in many cases. ]
[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. [More thoughts](https://worldbuilding.stackexchange.com/questions/197555/does-the-sun-provide-enough-energy-to-accelerate-a-large-ship-to-a-decent-propor?noredirect=1#comment614113_197555) on hard science possibilities for interstellar colonization and the request to check my understanding of physics. Suppose you have a fully self contained colony ship. They have some giant reactor producing power and as long as the reactor has fuel they can produce everything they need for life support on board. This could be with green houses to grow plants for making oxygen and food or it could also be pure chemistry. According to my understanding of physics, as long as it is a closed cycle within the ship all energy will eventually be turned into heat. And as they are in space the only way to lose this heat is through [thermal radiation](https://en.wikipedia.org/wiki/Thermal_radiation). The [Stefan–Boltzmann law](https://en.wikipedia.org/wiki/Stefan%E2%80%93Boltzmann_law) now gives a way to compute the energy the ship loses through thermal radiation. It only depends on the surface area of the ship and the temperature. It seems that for a fixed surface area and a fixed surface temperature this gives the exact amount of energy the ship needs to use to be in a stable equilibrium? If they use more energy the ship will heat up (which will also increase the thermal radiation), if they use less the ship will cool down (which will also decrease the thermal radiation). As thermal radiation changes with the 4th power of absolute temperature, there is some room for maneuvering but if the energy use is off by an order of magnitude or two in either direction, they have a problem. Edit: Some specific numbers. In my last question linked above I learned that you need the energy equivalent of the entire energy output of the sun for a few days to accelerate a large space ship to half the speed of light. This means that if the space ship uses the equivalent of all the solar energy hitting the earth (around $10^{16}$ Watts) for life support and other internal energy needs that is negligible in comparison even over a timespan of decades or centuries. But if we assume a spaceship as a 10km cube and a temperature of 300 Kelvin the total heat radiation by the Stefan-Boltzman law above is only $5.67\10^{-8}\300^4\(6\10^8) W = 2.75\10^{11} W$. Meaning by my naive interpretation of physics they would need to use energy of that order of magnitude to not overcook themselves, for $10^{16} W$ they would need a much much bigger or hotter spaceship. [Answer] ## Isolate your habitation section from your reactor section Stefan–Boltzmann defines the energy blackbody emissions as: ``` P = AσT⁴ ``` Or for those of us who actually like to know what our variables means: ``` $radiantEnergy = $surfaceArea 5.67 * $temperature^4; ``` Common logic tells us that the correct course of action is to increase the surface area, and yes, this will help a bit, but look at that power of 4 on the temperature... that is a nice big exponent to exploit meaning there is a lot of room for exponential growth by just getting a little hotter. The hotter you are, the faster you radiate heat; so, if you want to push a maximum amount of heat off into space, getting hotter is the way to go. Now because people live on your ship, getting hotter everywhere is a bad idea... and totally unnecessary. By separating your ship into capsules that are attached by thermal resistant materials, you can heat each part of your ship to its maximum threshold while keeping living quarters relatively cool. For your habitat section you need to maintain a temperature of about 293K, but that is just what is good for humans to live in. A much larger part of your ship will be the greenhouse, but no-one says you have to live off of vascular plants. By farming Algea as you main food source you can crank this compartment up to 335K... but the next part will make this a trivial measure. Lastly is the reactor section. Now this is where establishing a true MAX has to digress a bit from "hard science" and into "science based" because we really don't know what power sources or materials we will be limited by in the future. However, if you were to construct a large capsule with thermal properties similar to tungsten, you could heat up your rear section to somewhere in the range of 2750K making it glow like a giant incandescent lightbulb... at which point it could passively heat your other 2 sections if you put it at the right distance. So, let's say your ship is made of 3 equal sized capsules, all with a surface area of 1/3 the OP's proposed total surface area, this gives your habitat the ability to compensate for 9.17e10W, your farm section 1.57e11W, and your reactor section 7.12e14W. This is because your glowing hot reactor could offset ~7,750 times as much heat per surface area as a room temperature module. This still only puts you at about 7% of your target... which is honestly not that bad. This still keeps you working in human time scales, but there are two things you can to to further boost this if you really want to hit that 1e16W benchmark. First, there is no reason the modules should be the same size. Your farm will probably need to be much bigger (thus more surface area) than your habitat, and depending on choices you make as an author, your reactor/fuel/propulsion section could have much more surface area than the rest of your ship if you picture a fuel system that stores hydrogen for fusion with no oxygen to react with, you might as well store it as a super heated plasma as long as it does not get hot enough to melt your tungsten containment tanks. In this case, if you make your ship something like 5% habitat, 10% farms, and 85% reactor section, you could get yourself to about 17% of your target goal. Secondly, you can go with higher heat. I chose 2750K as the operating temperature of a lightbulb... much hotter and tungsten become structurally unsound, but adding a meta-material into a space setting that can operate higher than this is not implausible. If you go with a ship that is 85% hot capsule and about 4280K, you should be able to reach 1e16W with that total surface area... but that would significantly exceed the melting point of any known element; so, if you are going for a more hard science universe, I would accept the slightly lower power output. [![hot reactor ship](https://i.stack.imgur.com/5w1NW.png)](https://i.stack.imgur.com/5w1NW.png) [Answer] ## Ships can Control Surface Area and Temperature A star or planet has a (relatively) static surface, and heat will always flow from hot to cold. A ship is significantly more complex. To heat up a ship, you can cover it with an isolating material. Heat flux from the covered areas will decrease, and the rest of the ship will warm up. Conversely, to cool a ship you can transfer heat to certain exterior sections using a heat exchanger. Common household heat exchangers include Air Conditioning and Refrigeration - any case where you use movement of a working fluid to move heat between two locations. Imagine a large set of wing-like radiators protruding from the ship. They have high surface area to radiate energy in every direction, and the ship can control their temperature (and therefore the amount of heat they radiate) by pumping fluids into the structure. The key here is that the ship is not some static, uniform body, but a complex system that can impact its own emissions by expanding a small amount of energy. [Answer] Addressing some confusions in the original question > > This means that if the space ship uses the equivalent of all the solar energy hitting the earth (around $10^{16}$ Watts) for life support ... > > > First at all clarify for yourself your naive interchangeability use of energy (as measured in joules) and power (as measured in Watts). A generation ship is not an totally opened system in which any energy that you use immediately transform in heat that needs to be evacuated immediately. Then, what if they don't need the solar entire power that hits the Earth? It's not like 100 million people needs the power which sustain the entire life on Earth, from the depth of Mariana trench to the top of troposphere, including the formation of hurricanes, ocean currents and rain. > > But if we assume a spaceship as a 10km cube and a temperature of 300 Kelvin the total heat radiation by the Stefan-Boltzman law above is only $5.67\10^{-8}\300^4\(6\10^8) W = 2.75\10^{11} W$. Meaning by my naive interpretation of physics they would need to use energy of that order of magnitude to not overcook themselves, for $10^{16} W$ they would need a much much bigger or hotter spaceship. > > > Not only the assumption that you need the Sun output just for 100M people is wrong, but the rate consideration are totally exaggerated - you simplified your model too much. 1. the ship is not a lump of steel or something. You have multiple energy sinks inside the ship - the very food that you grow will take light and heat to run those biochemical reactions and store them as bound energy. Which means the temperature of your ship isn't going to increase immediately (the way it happens with a lump of steel). True - eventually, you are going to have it transformed in heat (after you eat, digest and burn those nutrients), but there's be at a slower rate than if you just apply the same extra energy to a lump of steel (or amount of gass) 2. a generation ship will need to be masters of recycling or it won't last long. Heat is one thing that one can recycle to some extent. As an example, you have a large storage of water that you can afford to heat up using a thermal pump - and you will get to reuse part of the stored heat (the thermal gradient) sometime down the line. By doing it, you will create extra heat in operating that those heat pumps. But because a heat pump can reach 600% energy moving efficiency, you will only need theoretically* to get rid of 1/6 extra heat. Do this in many other sophisticated ways and you address the rate in which you need to purge "waste heat" (heat in spatial configuration with such a low gradient inside the ship that you can't use to extract controllable power to run your processes. The equivalent of the "heat death of Universe" inside the microcosm of your ship) One on top of the other, in principle, you run your ship by recycling everything, with only the cost of extra energy required to recycle everything. And you can lower the amount of energy required to recycle everything to a much lower value than the cost requiring "brand new energy from the Sun in every moment and throwing the excess away." 3. All of the above would address the rate of the heat purge, but bottom line you will still need to purge it in the end. You can still control how you purge it into the lower temperature of the surrounding space. All your ship being thermally isolated with the exception of the radiators means that, by controlling the direction and the radiating area and the temperature of those radiators, you can use the thermal radiation for propulsion. Happened inadvertently with [Pioneer 10/11](https://en.wikipedia.org/wiki/Pioneer_anomaly) anisotropic radiation pressure slows them at a rate of 1 km/h over a period of ten years. --- Bottom line: I don't know how or if a generation ship can be actually built, because it will be a matter of carefully trying to solve a great number of problems. What I can tell for sure is that you can't demonstrate the possibility or impossibility of a generation ship with computations on the back of a napkin using dumbed down models ]
[Question] [ In the land of Gnosticia, legend speaks of a messiah who would lead his chosen people to greatness as a far flung empire. This prophecy came to pass when a child was born to a virgin woman, and would go on to teach his people the gifts of magic. After some time, this child would ascend to the heavens and become " The Demiurge", and would continue to be worshipped by his people as their god. Through this being, they would harness the power of magic as they competed with other tribes in the ancient world. The Demiurge left behind three systems of magic to the gnosticians. These systems are seen as ways to communicate with the universe around you through a series of pre-ordained steps in order to get certain predictable results. They would all be capable of accomplishing the same things, but in different ways and extents, such as making fire, summoning lightning, or creating familiars. This would be similar to inputting code into a programming language, the equivalent being Java, Python, and C++. The type of system would be the language, the rituals as the code, and the activation as the compiler. The first type would be simple and easy to understand and master, but would be limited in capability and scope, and ultimately not very powerful. At the other end of the spectrum would be a system that provided far more control and flexibility, allowing for more powerful effects and better results. However, it is far more complicated, with more rituals, incantations, and years of study, making it difficult to master. The medium range would be a mixture of both. Various gnosticians take up learning a system according to his or her temperament. As a young god, the Demiurge must compete with older deities much older and secure. The followers of beings like Yahweh, Moloch, etc, have had years head start honing their craft in magic, each producing a single magic system that operates as a " universal coding language ". This allows their followers to only need to study one system of magic instead of three, saving much time and resources. This allows these universal magic systems to be easier to study, instead of having to re-learn mage-craft when studying a new form of magic. This puts the younger god and his people in a bad position. What advantages would learning three magic systems have over one that is all-inclusive? [Answer] More eligible candidates to be practitioners All of those old religions needed the same kind of people to work the magic: sort of spooky, deep set eyes, great at memorization, poor people skills. And there are only so many of them to go around! By spreading or possibly sprawling out the magic types you can have many other types of people learn to be practitioners. <https://web.cortland.edu/andersmd/learning/mi%20table.htm> [![enter image description here](https://i.stack.imgur.com/9dRsi.jpg)](https://i.stack.imgur.com/9dRsi.jpg) With a magic for each kind of intelligence... ok , a magic for 3 different kinds of intelligence, one could have expert capoeira practitioner magics, breakdancing magicks and aggroballet kung fu magic! Those 3 actually might all be the same kind of magic and then there would be one for people who could recognize plants and then one for persons with the sensitivity and capacity to tackle deep worldbuilding questions but who could also do some aggroballet. And who also can recognize several plants. In any case, you see where I am going. There is a whole world of people who do dance and martial arts and worldbuilding and up until this young Demi Urge none of them practiced any kind of religious magic because they were too buff, ripped and good looking. Now they can! [Answer] To encourage co-operation. There are many things that can not be done except by magic, and no form of magic can do them all. Thus, the magicians have to learn to work together to divvy them up. This helps keep their country peaceful, and therefore prosperous. It also means that they are encouraged to share knowledge in a way that allows them to accumulate it fasters. [Answer] > > What advantages would learning three magic systems have over one that is all-inclusive? > > > Improved specialization and synergies. Each of the individual magic system can go more in depth with the specialization for a particular feat. When put together, the 3 of them have an overall better capability than the generic one. Make the comparison between having a swiss knife or a set of tweezers, screwdriver and Allen key: for a long and dedicated work, the set of tools will be better than the swiss knife, because it will fatigue less the operator and also allow joint usage. [Answer] Each system of magic has different efficiency, casting speed and spell writing duration. Python: Pros: Very fast to write, very concise and can be changed mid spell. There are also vast prewritten spells on searching for patterns and scrying. No delay in casting, the casting begins immediately. Cons: However, the spells cast slower and it won't work in low mana situations. Very inefficient for casting the same complex spell multiple times. Actually uses C to do the commands, but the wrapper allows you to do a lot without dealing with C. Java: Pros: Moderately fast to write, mostly concise, but can't be changed mid spell. Has more complex magic runes for more complex spells. Fairly efficient for running the same spell multiple times. Fast cast time Cons: Requires a special rune stone to be installed in the area to function. Not as efficient as it could be. Fairly verbose in comparison to Python. There is a slight delay between cast and execution. C++: Pros: About as efficient as you get. Works everywhere. The most well known by the old wizards. Capable of doing things more accurately than other systems. Super fast cast time. Cons: Takes the longest the write and has the longest delay to cast. Depending on the size the spell execution takes minutes after the cast. you are basically messing with magic directly in this system, so you can cause miscast where you access a forbidden secret (seg fault) pretty easily. If you are casting cantrips for a simple problem you might want python. A more serious project with speed requirements might need Java. Heavy duty work or embedded rune work requires C++. [Answer] ## Specialism In my work (programming) we have two kinds of people: Generalists and Specialists. The Generalists can do most things reasonable well, the Specialists a few thing very good. The logic behind this is very simple. If you have 1 hour of time and ... * ...spent that on 2 things, you're now 0.5 adequate in both * ...spent that on 1 thing, you're now 1.0 good at one, 0.0 at the other. Generalists are fine for the basic and broad employability. Specialists are good for the hardcore tasks which a Generalist cant do (or would take a lot of time). ]
[Question] [ I have a very specific setting in mind that can be pretty much summed up as "Wild West with Dinosaurs". However, I'm still trying to figure out the details of just how the people native to a rural county between Wyoming and Montana would deal with both the sudden massive environmental changes as well as now being completely separated from the broader infrastructure of the United States forever. Why and how it happened isn't important. Somehow a rural county during the late 1920s was just teleported back in time, which for convenience sake I'll just call the "time change". The specific time period is the late Campanian stage of the cretaceous period (about 75 million years ago). So no T-Rex or Triceratops, in their stead there's Daspletosaurus and Chasmosaurus just to name a few. The climate was warmer and the area between Montana and Wyoming at the time was more swamp like and was close to a massive inland sea dividing North America in two Much of the infrastructure of the county is intact initially at the time change, but the environment surrounding it is the unaltered cretaceous environment. As for the population, let's say the county has between 10,000 and 15,000 initially. The wildlife from the anthropocene era within the county's area were also brought along for the ride in the time change. [Answer] ## In the short term they might survive, on the long term they are screwed There are a lot of things that can go wrong if a 20th century Wyoming-Montana town got transported to the Campanian period. Also for references check out my answer on ([this question](https://worldbuilding.stackexchange.com/questions/175181/benefits-of-time-traveling-back-to-the-late-cretaceous-period-economic-financia/175197#175197)), which covers a lot of the same things. Some of these problems include: A lack of edible vegetation among the native flora You got really, really lucky by proposing the Campanian as your time period of choice. The Campanian is the point in time that the conifer-dominated floras of the Mesozoic were replaced by the angiosperm-dominated faunas that characterized the Cenozoic or later. Campanian-Maastrictian forests would have looked essentially modern with an odd abundance of gingkos and dawn redwoods. However, the broader problem is that most of the edible plants we know and love had not evolved yet by the Campanian. Most edible fruit and nut-producing plants hadn't evolved yet, because these plants evolved their edible seed coverings due to coevolution with primates and other fruit-eating Cenozoic animals. Maples (maple syrup) and oaks (acorns) also hadn't evolved by the Campanian. Your sources for native vegetation are going to be few. * Sago palm (very toxic if not cooked properly) * Pine nuts * Fern fiddleheads The good news is that the native wildlife should be fine to eat as long as it's sufficiently cooked. Disease transmission from eating dinosaurs should be low, though not completely impossible. Meat is meat and hasn't changed its structure in hundreds of millions of years. Dinosaur meat should be as safe to eat as alligator or chicken. Large animals generally don't have toxic meat because it costs a lot, metabolically speaking. The biggest thing to worry about would be if the local animals have accumulated arsenic or heavy metals in their tissue due to the plants they ate. But this is unlikely. Huge risks for crop failure So, the thing about Wyoming and Montana is there isn't a lot of crop farming there. It's some of the driest territory in the lower 48 outside of outright deserts like Nevada and most farming there today is restricted to areas where it's easy to get water, especially around large rivers like the Missouri and North Platte. So very few crops are going to be taken with this town into the Cretaceous, which raises the risk of a single wheat blight or corn smut completely wiping out the town's food supply. In the 20th century if you have a mass crop failure you can always replant the wheat and corn fields with seeds from elsewhere. In the Cretaceous you can't. Wait, there's more. The Cretaceous lacks any native pollinators for major crops like butterflies and bees. Good news is that major American staple crops like wheat and corn can self-pollinate or pollinate via the wind and thus don't need bees. However any crops that do need pollinators like apples or most other domesticated plants would be highly dependent on whatever few bee hives or wandering butterflies were grabbed by whatever cosmic power dragged the town back into the Cretaceous. The survival of the pollinators, like the crops, would be heavily dependent on whether they are lucky enough to not get snapped up by some Cretaceous insectivore. Cattle Trouble Wyoming and Montana's biggest agrarian output, bar none, is cattle, with sheep also being important in some areas. This means cattle are going to be the town's main source of food unless they can start reliably hunting dinosaurs, especially given they can't supplement their diet using local flora and wheat and corn supplies will be limited. As with domestic crops, cattle will be highly vulnerable to being wiped out by disease given how few of them there are. One cow with foot-and-mouth disease might end up wiping out your entire herd. The bigger problem will be native predators. Big predators like theropods will be leery of novel prey like cattle but eventually they will figure out they are viable food sources. Grizzlies, coyotes, and wolves in modern Wyoming and Montana rapidly figured out that cattle were easy prey, despite their ancestors having never seen domestic cattle before. This will be amplified by the fact that cattle ranching practices in Wyoming and Montana often involves just leaving cattle where they die rather than disposing of the body. This will result in native predators having an easier time associating cattle with food (This is one reason why modern ranchers in Wyoming sometimes get wolf problems). The native predators will also lack any intrinsic fear of humans. Once the theropods do figure out that cattle are easy prey, it's open season on the cattle. Cattle are almost the ideal prey size for large predators like tyrannosaurs, being about the size of a juvenile hadrosaur. Additionally, the cattle breeds used in the 1920s-1930s in Wyoming and Montana tended to be the more docile breeds used today rather than the more aggressive semi-feral breeds such as the Texas longhorn. Longhorn will fight back against predators, more modern beef cattle like Angus are so docile that (in Wyoming mind you!), they've been known to see their calves slaughtered right in front of them by coyotes and do nothing about it. They won't meaningfully fight back against a tyrannosaur. Another problem is that cattle waste might not break down. There were likely dung beetles and other decomposers would be around, but they would be adapted to breaking down dinosaur dung, not mammal dung. So what would end up happening is you would get massive pile-ups of cattle dung that would never go away. This is what happened in Australia, where you had cattle dung just plain not decomposing because the native dung beetles preferred marsupial and bird dung. The only way this wouldn't happen would be if you brought enough modern dung beetles with you, but even then the small founder population might end up shredded by small mammals and reptiles and go extinct. It's open for debate whether your cows would even be able to survive long-term. Wyoming thrives because it has huge areas of grassland with little water, and there isn't much else you can do with them than use cows to turn that grass into edible calories. It's not clear if they could do the same in a world where most of that grass has been replaced by [ferns, horsetails, and relatives of cannabis](https://www.google.com/books/edition/Cruisin_the_Fossil_Freeway/eMzGz-X6xQIC?hl=en&gbpv=1&dq=cannabis%20cretaceous&pg=PA76&printsec=frontcover). Some edible plants like buttercups and nettles might be around, but its unclear how much. Some native plants might have anti-dinosaur toxins and be lethally poisonous to cattle. The large quantities of herbage necessary to support cattle herds might not be present. Enjoy your scurvy This brings up a bigger problem. Your people will eventually start suffering from massive vitamin deficiencies. A diet composed solely of dinosaur meat, beef, and edible grains with no fruit or leafy vegetables anywhere in sight would soon be suffering from scurvy. Best options? [Hopefully some of the rare orchards that exist in Wyoming or Montana might have survived](http://www.uwyo.edu/barnbackyard/_files/documents/magazine/2014/winter/010114bbwyappleproject.pdf). Alternatively you might be able to figure out some part of native wildlife that has vitamin C and start eating that for all it's worth, like how the Inuit survived on a solely meat-based diet by eating animal liver, brain, and seaweed. Gradual loss of advanced technology Towns in the American West in the early 20th century weren't full self-sufficient. They were heavily dependent on the railroad sending raw material out of the town in exchange for machinery and processed goods being brought in. This includes things like gunpowder/firearms, gasoline, farming equipment, etc. Neither Wyoming nor Montana have never had much of a manufacturing industry. What would end up happening in the long term is that your 20th century technology would break down due to long-term use and inability to replace them. More notably, eventually you would just plain run out of gunpowder to use for firearms. Insufficiently powerful firearms One problem you might have is that people might not have powerful enough firearms to meaningfully ward off dinosaurs. By the time of the Great Depression the largest mammals like bison and grizzlies were restricted to the Yellowstone Basin, and animals like wolves were outright extinct in Wyoming until they were reintroduced. Most firearms people had are going to be hunting rifles with the caliber tailored for hunting bighorn, elk, mule/white-tailed deer, and pronghorn. Maybe something like a Winchester. Is a Winchester going to stand up against a Daspletosaurus or an angry ceratopsian? Best option for long-term survival? Revert to a seminomadic hunter-gatherer lifestyle with some herding and spend your time eating baby dinosaurs and dinosaur eggs, which should be everywhere because dinosaurs are explosive breeders. Supplement with what little cattle survive as necessary. Based on what technology is available to a 20th century Wyoming/Montana town (e.g., ferriers), you might be able to retain iron working and use iron spearheads and arrows. [Answer] You have many problem. First no fuel and no electricity which means most of modern technology becomes useless in short order. I will tell you from experience when I had to work in a wild life refuge where power tools were forbidden, most people do not know how to do things entirely by hand anymore and even fewer have tools to do so. Few know how to hunt without guns. Few people know how to make glass, or bricks, or iron, especially without modern tools. The great depression is not far enough in the past to get away from this. They may well starve, they will have little stored food once the electricity goes out. enough for a few months at best. They likely do not have anything to plant. They likely do not even have seeds for the next round of planting unless it is very close to planting season. Buying seeds is more common than keeping them. That is IF they even have human food producing crops, few places in those states do, mostly only in the modern age with modern irrigation. Wyoming had almost no crop agriculture at the time, the ones that did where strictly grains or animal feed. Montana is better off agriculture wise even if it ends up short on almost everything else, downside Montana is almost entirely underwater, so you are probably stuck with Wyoming. Although if you go at the very very end of the cretaceous this is not true. Go 60 million years ago and you conditions similar to the modern east coast, lots of forest and good soil. What about ranches you might ask, they may well do more harm than good, groups of easy to catch cattle and sheep are just going to act as a predator magnet, you are talking about the time of huge pack hunting dinosaur predators. There is almost nothing your humans can eat, no fruit, no recognizable plants, meat is it, and what bullets they have won't last long, and they don't have the knowledge or infrastructure to make more. Livestock may run into similar problems with few plants they can find edible especially with the climate change. They will probably have to move. With the landscape change they may not have a nearby fresh water source especially with no pumps. They don't have enough people for a stable population, a small rural community will not have enough people to maintain a population, especially once disease and dinosaurs set in. The smallest town in Wyoming is Bob Wyoming population 4. If they survive it will be as hunter gathers, in which case their population is too large, and they will likely have to split up in many small groups. Maybe, maybe if they are absurdly lucky they have enough seeds and skill to restart agriculture, but they will have to survive many years before they will be producing enough to be self sufficient from agriculture. ## Solution: You may want to consider going with multiple towns, maybe even the entire state of Wyoming. this gives them what they need to keep everything going. There were coal mines and oil refineries in Wyoming at the time plus an abundance of equipment to make both. Wyoming was actually experiencing a boom in both coal and oil in the 1920's. this gives you some electricity, oil, and trains. which will go a long way to making things better. Even better a lucky train might be loaded with seeds for crops or machinery for well machining. There was actually hydro-electric dams in Wyoming at the time if you want to handwave them somehow still being in a location that works. Electricity makes it possible they could be making their own bullets, although expect a reversion to caseless ammunition as they will be hard pressed to get them metal needed for brass. A larger town also means a lot more people to start with so much greater likelihood of having the right skill sets to keep technology going. A 1920 Wyoming census they [may be useful](https://www2.census.gov/library/publications/decennial/1920/bulletins/demographics/population-wy-composition-and-characteristics.pdf). keep in mind in 1920 there was only 194,400 people in the entire state of Wyoming, Montana had far more despite being further north. You could move the entire population of both states and get what you want. Both states would also give you the tech to extract and use: oil, coal, copper, iron, and food, which will allow a reversion too wild west level technology but not past it. You will have a massive die off but you will have that anyway. you also start with enough livestock some surviving is likely. As a side benefit using the entire state will give you a buffer to slow the encroachment of the native wildlife, so your humans have some time to get everything set up. [Answer] I think they will have huge problems. They basically land in a wild region which they don't know with scarce supplies. I say scarce because I doubt that they have supplies sufficient for at least 1 year of anything. With those supplies and what they have with them they need to: * protect their settlement with something sturdy enough to push away curious dinosaurs. * fence a large enough plot of land to try some agriculture. I doubt planks and barbed wires will do anything against dinosaurs. * plow that plot and make it suitable for farming. I doubt they have enough forage for the beasts of burden or fuel for the tractors to complete the task. And they know nothing about the local weather patterns. * Defend the plot from grazers. If a mole in your garden is annoying, imagine a dinosaur. * Gather food and water. I doubt that Montana had plenty of dum dum bullets at the time. All the above points seem to pointing in the direction of a large number of casualties due to attacks from predators, hunting incidents, farming incidents and famine. Top it with lack of medicines and you have a pretty grime picture. [Answer] The biggest problem I can see is farmland. Not so much that dinos wandering over a wheat field will ruin the harvest (though it will) it's that they know NOTHING about soil content, weeds, other plants, etc etc etc. I would say your best bet is to transplant the town and a decent amount of surrounding farmland. That'd give them (hopefully) some silos of grain to survive the short term and various farming implements to maybe get things going in the medium-long term. Though with the temperature change et al they're unlikely to get harvests in successfully for years. Speaking of short term, I don't think predatory dinos will be a huge problem at first. Most wild animals are intensely conservative, especially predators. If I drop a human by a pack of wolves or pride of lions that has never seen a person before their instinct isn't "attack and get free lunch" it's "man that things weird imma stay over here." Eventually of course this would change, but at least they'd be able to avoid widespread predation. Especially if you "Swapped" a few square miles so they wouldn't instantly be in something's territory. Another huge problem they'd have is identifying things to eat. Sure a dino is tasty but plants? It'd be a crapshoot, literally. You'd lose dozens of people trying to figure out which local plants are safe to eat, even in the best of circumstances. Diarrhea, straight-up poisonings, you name it. With 65+ million years of evolution between them and Paleo-botany more-or-less not a thing (certainly not for a rando midwest town) they'd have almost nothing to go on. At best they could find some small mammal, nibble whatever it eats, and hope to eventually find something you could cultivate in quantity. Good luck. That being said, they'd be REAL efficient hunters. Remember the Dodo, which was so unused to people you could just walk up and kill them? Think that, but for literally every species on the planet. Humans aren't a thing, so to dinos they're not a threat. It would take a LOOOONG time for animals to figure that out, especially since humans attacking herds would shoot animals from afar. We're probably talking multiple-generations. So even if your agriculture goes to crap, you'd be unlikely to straight-up starve. This super-hunter status might even help with the big carnivores, either by hunting them to extinction in the local area, or by killing big herbivores far enough away from where the town is that the predators are satiated and distant from the town itself. ]
[Question] [ Very simple I need some really big and imposing marines. The enhancements make them stronger with faster reaction speed, bone strengh and the works. Why would these marines be really tall as well? Is there any advantage to them being tall if they are deployed on space stations and ships? [Answer] ## Better Power Armor Based on your previous questions, I will assume you have a setting that includes power armor. One of the biggest complications in designing power armor is that you need a lot of space around the body to fit the exoskeleton and chunky armor plates, which leads to issues with articulation. The stockier your soldier is, the smaller spaces you have to work with for this; so, a tall, lancky soldier would put a lot more distance between your points of articulation allowing you to make your armor plates thicker and your exoskeleton stronger while still being able to move around your user. In my previous answer to your question regarding the use of 50cal machine guns, modern body armor capable stopping such a weapon would have to be about to be about 3cm thick... doable but only in select locations. With longer appendages, you could design articulating plates than can be this thick around your entire body giving much better protection, and also give your space marines a tough enough of a powered exoskeleton to carry larger firearms that might punch right through the thinner armor of shorter soldiers. [![enter image description here](https://i.stack.imgur.com/18W9L.png)](https://i.stack.imgur.com/18W9L.png) As for your soldiers being breed to be overall "bigger" and "stronger", this part is wholly unnecessary. Machines are proportionally much stronger than biology; so, if you make your space marines tall and skinny, then you leave more room for robotic strength enhancements. Either way your space marine ends up the same amount of bulky in full armor, but by being thinner, more of that actual bulk is robotics and armor. [Answer] Efficiency, economy You want the most soldier for your money. Best intimidation factor, best carrying ability. Training a midget costs exactly the same as training a Conan. And training cost is the #1 cost in any military that uses professional troops, not conscripted cannonfodder. Same for equipment, even to a partial extent clothing and armor. A sss-tiny soldier's boot costs just about as much to make as an XXX-Large. And the Conan can carry a Vulcan Cannon over his shoulder while storming the enemy, while a midget struggles with a single-fire 12-gauge shotgun. Conan can carry a lot more ammo, withstand more recoil, hit harder in hand-to-hand combat. Also, durability in combat. Shoot the Conan in the arm with a 9mm round, and unless you hit a bone, he just charges on. Shoot the midget with the same 9mm round, and his arm is off. Yes the Conan is an easier target, which counts against him. Also more effort to feed, transport. But these are relatively minor matters. > > Using Conans vs. Midgets to exaggerate the differences, but the same argument goes for intermediate sizes, just less obviously so. > > > [Answer] To Reach Things I'm reminded of Ender's Shadow/Enderverse Battle Room maneuvers. The gist is that kids at a space station military school play a 0-G game of laser tag in a box against other groups of kids. Bean, the smallest kid, has some problems with this as the handholds on the walls are spaced far enough apart that if he flies poorly he lands in a place with no handholds, and he bounces away from the wall instead of being where he needs to be. Your super-soldiers could have similar considerations in mind when they're made Tall. Above and beyond the need for a bigger body to accommodate the extra muscle/fancy bones/what have yous, a physically taller body would allow for greater reach when it comes to grabbing hold of stuff in a 0-G environment. As long as they can still fit through ship's corridors with relative ease, you'd want them as tall as you can get. That way when fighting on a ship or station's hull, or in, say, the cargo area of a kilometers-long-freighter with no gravity, they'd be more maneuverable than a normal 5"10ish person. (or at least better able to get where they needed to go, maneuverable might not be the right word.) Added to this "maneuverability" in 0-G, you also have the traditional intimidation factor that comes with fighting someone larger than yourself. It's instinctual and not to be underestimated when fighting in close proximity. The added height/dis-proportionally long limbs may also be an ID marker in the field. If your Space Marines are easily identifiable as such, AND are super-human killing machines, making them easily identifiable is another psychological advantage. For example, the Spartans had a specific symbol on their shields, and they sparked fear in their enemies. But in one battle against Thebes the Spartans used not-spartan shields and the Thebes held their own, whereas if they'd known they were fighting SPARTANS they may have broken and run. So if your Space Marines look physically different it'll let your enemies know they're up against the First Team and maybe give up before the fighting even seriously begins. [Answer] Accidental side-effect. While working on other traits such as efficient use of oxygen and stronger muscles, they found it had the effect of increasing the size of the soldiers. Sure, they can sing the praises of the intimidation factor and the ease of fitting power armor, but had it been the other way round, they would be singing the praises of lower calorie demands and decreased chance of cancer. [Answer] Born in 0 g. It turns out humans born in zero gravity get really tall. Unmodified children can grow up to eight feet tall and sometimes parents of children destined for civilian life will induce puberty early in order to halt growth at manageable heights between 6 and 7 feet. The really tall ones struggle if they are ever in a situation with gravity because generally in addition to their height they have low muscle mass. 0G spaceborn children chosen to be space marines are often allowed to reach full height. Enhancements augment muscle mass to some degree but these persons are still lanky as compared to persons born in a gravity well. Really, strength does not matter if you have on power armor which they invariably do if they are working or on a planet surface. If power armor presents poor optics for a given situations, the spaceborn marines planetside will still wear a light exoskeleton frame. [Answer] Because the dictator who ordered them is really short and is trying to compensate. Being taller comes with spine issues, it's actually an advantage to be a little shorter when hauling the sort of loads soldiers deal with, this applies even more so to special forces. The palace guard should of course be really tall. [Answer] Two possible reasons: [intimidation](https://www.oglaf.com/plumes/) and the ability of moving more quickly (longer legs means higher speed e.g. when running). It could also be a necessity if they need space to store synthetic enhancements (e.g. oxygen reserves, food supply, chemicals) that can't as easily go in the outer armor. [Answer] Bigger usually = better in combat There's a general observation in nature that bigger usually means better when it comes to combat between animals. Bigger animals can more easily win fights and monopolize resources compared to smaller ones. Size generally provides a multiplicative advantage because while size (in humans usually measured as height) increases linearly, weight increases cubically [due to the square-cube law](https://en.wikipedia.org/wiki/Sex_change#In_animals). What this means is while a 6 foot (183 cm) human might weigh 200 lbs (90 kg), an eight foot (244 cm) human will weigh 215 kg (474 lbs). These differences in weight are a big deal. They're the reason why you see weight classes in sports like wrestling, MMA fighting, or boxing. This is because pound for pound, assuming a fair fight and evenly skilled combatants, the larger combatant will win most of the time. Smaller people can win by being more skilled, having better weapons, or using better tactics (element of surprise, etc.), but they won't win in a straight-up fight. Larger size would also mean that your super soldiers could carry heavier gear or wield larger caliber weapons than regular soldiers. Two of the biggest constraining factors in modern soldiers are long-term fatigue in carrying the very heavy backpacks and gear that most soldiers have to lug around, and the weaponry they can carry is limited by how much the human body can easily lift. This is why in science-fiction franchises like Warhammer 40k or Halo you see super soldiers wielding weapons that are handheld rocket-launchers or particle cannons, or even outright lifting an emplaced heavy machine gun from the ground and wielding it as if it were a minigun. Larger size also means it takes less energy per pound to move from one location to another. Relative to body length, migration is much less of a big deal for an elephant than a mouse. This is why a lot of migratory animals are very large. This might also mean your super-soldiers have an easier time on long marches. There are distinct disadvantages to being larger in combat. 1. Bigger soldiers are larger target for firearms 2. Bigger soldiers require more calories to support and if you can't feed them won't be cost effective 3. Bigger soldiers may not be able to squeeze into enclosed spaces like sewers or tunnels to fight in asymmetrical warfare 4. Super soldiers can't go undercover. A seven-to-eight-foot-tall supersoldier can't easily pretend to be "one of the locals". But a lot of these aren't absolute deal-breakers if you can logistically deal with them. If you're looking for reasons for them to be big, here you go. ]
[Question] [ Is there a reason for a human sized parasite to infect other animals if it can very well hunt alone and defend itself? I thought about it injecting eggs into other animals, but that's pretty much killing it and using it as food, not really parasitical. By parasite I intend something that is not entirely predatorial, like a vampire would probably only care to suck dry a prey and kill it, but it's not like it's gonna get attached to an animal for long periods like a leech would or a lamprey. But then again, a giant leech or lamprey would still kill any land and most water animals in one bite. [Answer] Wasps do this - make a giant wasp Some species of wasps both eat other creatures and inject eggs into them. > > Wasps tend to be omnivorous. They prefer a diet that constitutes of > nectar, honeydew, and a vast range of invertebrates such as ants, > cicadas, butterflies such as blue morpho butterflies, spiders, > caterpillars, and flies. > <https://www.bioexplorer.net/what-do-wasps-eat.html/> > > > > > Terrifying giant parasitic wasps that lay eggs INSIDE baby insects > using ‘sex sting’ discovered in Africa > <https://www.thesun.co.uk/tech/10099018/parasitic-wasp-egg-sex-sting/> > > > [Answer] Injecting eggs into other animals and Killing them for food is totally different. When these parasites lay their egg inside another animal, say a cow, then the egg gets a relatively safer environment to develop and constant warmth to mature. When the baby comes out of the egg, it gets instant fresh food and safety from the outside world, it can keep feeding on the host and by the time it eats enough of the host that the host dies, the baby is mature enough to survive further. You won't get features like these with dead animals. [Answer] If it's a colony of unicellular organisms (essentially a multicellular organism, but less, well, solid) it's perfectly feasible. The largest fungus on record lies underground and spans 3.5 miles, sprouting clumps of yellow-brown mushrooms above the surface to reproduce. Considering that's the largest fungal colony in the world, our colony should be perfectly capable of achieving human size. As for why it would infect other organisms when it can hunt and fend for itself, the answer is simple: 1. It can't obtain food by ingesting other organisms, it simply doesn't have the ability to. In other words, since it can't eat other creatures for food, it's an obligate parasite and needs to leech nutrients from a host. Likely ways are bloodsucking since the blood contains and distributes the nutrients gained from digestion or by taking advantage of the host's digestive process (like tapeworms do, perhaps?). So this creature must have a host to live. 2. Since it can't obtain nutrients on its own, it's not hunting for food, but rather for a host, which it will use its amorphous body to engulf and metamorphosize. Yes, you read that right. Either it'll break down and reassemble the host like a caterpillar in a cocoon, using retroviruses to incorporate its genes into the host so they technically become one entity, or it'll invade the host's cells (so it can access the nutrients supplied to and energy produced inside the cells) and alter its genome to suit its purposes. This parasite could be an interesting take on the whole zombie concept, a freaky alien monster, or the explanation behind the Imposters in Among Us. [Answer] Parasitic larvae. You have not said what "parasitic" means. I presume you want a creature that lives permanently attached to or inside the host's body. There are no human-sized creatures like that in the real world simply because no host is big enough. The next best thing is a parasite with several stages. The fully grown form is the size of a human. It hunts and kills things. It's only when it reproduces does the parasitism start. After mating the large creature injects its eggs into the skin of another large host. The young hatch inside the creature and, over the next few weeks, eat their way deeper inside. They then form a cocoon and metamorphose into their second stage. The second stage is still only about an inch long. It hunts and kills insects and over the next few years grows into the adult form. For extra size, the infection is set up so only one larvae survives after eating most of the edible material on the host, and all of its brothers and sisters. The coocoon gestates inside the desiccated body of the host. Hormones are released to make the host hide somewhere safe before dying, and to block decomposition odours that might attract other scavengers. Let's say with all that extra work the final creature that emerges is the size of a crab maybe? [Answer] Sustainability. Suppose I am a bandit lord. I can show up in a village, kill them all and take what they have. Ho ho! But when I come back to the village there are only weeds and empty houses because I killed everyone last time. Wah. If I can go find new villages that would work. But what if they are scarce? Worse, once I leave my territory what if there are other bandit lords out there who take umbrage with me showing up? Those other bandit lords are a lot tougher than villagers who go around in their underwear. I could kill all the villagers. But better is to show up and leave them alive and just take some of their stuff. Then let them go to work and get new stuff for the next time I show up. I can use my local village sustainably. Instead of predating on them, I am parasitizing them - drinking their blood little by little instead of eating their meat. I might actually occasionally be useful for them. If some small time bandit lord shows up thinking he will kill them all and take what they have, ho ho!, I can instead make an example of that bandit lord and have him dance in a cage while the villagers poke him with sticks. Parasitism could grade into a [protection racket](https://en.wikipedia.org/wiki/Protection_racket). [Answer] You might be interested in kleptoparasites: > > A bird, insect, or other animal which habitually robs animals of other species of food. > > > <https://centerofthewest.org/2019/03/25/kleptoparasites-pirates-world-birds/> The parasitic bird is perfectly capable of hunting but bullying and stealing is easier. [Answer] [Facultative parasites](https://en.wikipedia.org/wiki/Facultative_parasite) are an actual thing known in nature. Indeed there almost have to be in order for parasites to evolve, there has to be a transitional state between being a free-living animal and one that is dependent on living inside a host species. Some animals are free-living but have a larval stage that lives within another organism and eventually kills them (i.e., ichneumon wasps or the xenomorphs in Alien). This is technically not a parasite, it is a parasitoid. That said the boundary between the two is often blurry, insects have been known to be parasitized by ichneumon wasps and survive even after the wasp larvae pupate. Vampires were mentioned by a poster but that wouldn't necessarily be considered a parasite, in most cases they'd be considered a predator that merely happens to drink blood. To paraphrase E.O. Wilson, "a parasite is a predator that eats prey in units of less than one". Of course, the vampire definition is highly subjective. On the one hand, if the vampire can kill humans but more often feeds non-lethally, that is more parasitism. Additionally, one could argue the vampire living among humans and using human society for shelter counts as a form of parasitism. All this serves to highlight is the line between parasite and predator is very blurry. The problem you are going to face is you need a really, really big host organism in order to sustain a human-sized parasite. Like whale or sauropod-sized. The benefits of parasitism is that the host carries you around or gathers energy on its own, and then you swoop in and profit from it. The benefits you get are directly proportional to the difference in size between yourself and your host. If the two animals are about the same size, it makes more sense to consume it completely to recoup the energy costs of capturing it rather than just parasitizing it. By contrast a smaller parasite (e.g., a vampire bat) couldn't take enough blood to kill its prey even if it wanted to. You mention lampreys, but the thing with lampreys is lamprey attacks often are lethal because the sea lamprey is so large and stays attached for so long the victim dies of blood loss and organ damage. If sea lampreys "only" reduced fitness but weren't lethal they wouldn't be a horribly destructive invasive species in the Great Lakes, where they have almost wiped out the whitefish, lake trout, and burbot. [Perhaps unsurprisingly, larger fish are more likely to survive sea lamprey attacks, because the sea lamprey doesn't suck them dry.](https://www.sciencedirect.com/science/article/pii/S0380133003704961) There are a lot of difficulties in being a very large parasite: * From an energetic perspective, there is no benefit in letting your prey live. You are giving up free calories...for what? There is the argument that if you restrain yourself now you have prey for later, but animals aren't like that. Indeed, even to most human societies throughout history the idea of resource conservation was utterly alien, we only started realizing the importance of resource conservation when our societies started planning on the scale of years and decades rather than focusing on year-to-year survival. * If you are much larger than your prey, there isn't much of a point to hold back because it's more energy efficient just to eat them and get all the nutrition. Otherwise you have to chase them down again and drain them again. * You have to waste additional energy restraining prey that is close to your own size. You can't really sneak up on the prey as easily as a smaller parasite like a vampire bat, tick, mosquito, or leech could. At this point it stops becoming parasitism and starts being predation with extra steps. Probably the closest thing to what you want is a [micropredator](https://en.wikipedia.org/wiki/Parasitism#Micropredator) like an IRL saber-toothed blenny, some piranhas, or a cookiecutter shark. Lampreys, mosquitos, and vampire bats are technically considered micropredators as well. Saber-toothed blennies and some piranhas bite chunks out of larger fishes' fins and skin. Cookiecutter sharks are infamous for biting plugs of flesh out of large marine animals like big sharks, tuna, and whales. However, even in these cases the animals are still dramatically outsized by their hosts. ]
[Question] [ [![enter image description here](https://i.stack.imgur.com/kk7Tv.jpg)](https://i.stack.imgur.com/kk7Tv.jpg) What purpose could algae have to glow in the dark? I means, they have no eyes and they cant profit from it? from a predatory stand point it might as well signal grazer to come feast? Which is not very useful. In my fantasy world, I have phytoplankton that are glowing during the nights. What would drive evolution to produce glowing algae, that glow every nights and all night long, on a alien planet? Thanks for you input [Answer] Two possibilities: To warn off predators that the algae are bitter or poisonous. Easier to be recognized the second time. To attract commensal fish that will eat dead and decaying algae, or fish that would eat the algae. [Answer] Trees use smell. If your trees get eaten by masses of insects, nothing will seem to happen at first. But soon the trees will start to smell tremendously, and before the week is over masses of birds have eaten most of the insects and an equilibrium is created where some insects survive to eat the trees while birds get their share and enough trees survive. Algea would use light to attract predators of whatever eats them. Additionally the algea could use chemical synthesis for part of their process to stay alive which happens to generate light. Light can also be a warning if the algea is poisoness, signalling creatures not to eat it. This is similar to animals and insects like wasps that use bright contrasting colors to make it clearly visible that they might attack. [Answer] Bioluminescence is used as a defence mechanism to draw predators towards the creature trying to eat the plankton. Furthermore, the tiny flashes of light disorientate and surprise predators. [Answer] Imagine just minding your own business while you see a UFO. You would be pretty scared right? For predators, this is like the same thing. You don't mess with the things that you can't understand. What you can't understand is what you fear. Just think about deers. They are pretty smart when it comes to escaping from threats. But any car with it's lights on? They look at it like you would look at a UFO. So, long story short, it might glow to confuse and possibly scare any possible threats. ]
[Question] [ Inspired by [this article](https://www.nbcnews.com/news/all/speed-light-may-not-be-constant-physicists-say-flna6C9649533), which refers to two other articles. ([article 1](https://arxiv.org/pdf/1302.6165.pdf)) ([article 2](https://arxiv.org/pdf/1301.3923.pdf)) These articles suggest that the permittivity of free space ($\epsilon\_0$) might be adjustable by changing the density of virtual particles in a volume of space. The speed of light is : $c = {1 \over {\sqrt{\epsilon\_0 \mu\_0}}}$. $\epsilon\_0$ isn't required to hit any exotic values to create an appreciable increase in $c$. A simple $1 \over {100}$ reduction of $\epsilon\_0$ would obtain a new $c\_n = 10 c\_0$ I'd like a hard-science ([TRL 1](https://en.wikipedia.org/wiki/Technology_readiness_level)) sanity check of this approach to an FTL engine: * Emitters around the bow and sides of the vessel produce [colliding ion streams with sufficient collision energy to create Higgs bosons](https://www.symmetrymagazine.org/article/how-to-make-a-higgs-boson). * The Higgs fluctuations reduce the coupling between charge and mass, "de-massing" ([reference](https://nationalpost.com/news/higgs-boson-find-could-make-light-speed-travel-possible-scientists-hope)) even virtual particles * The "de-massed" virtual particles keep their kinetic energy ($KE = {1 \over 2} m v^2$), meaning their velocity would increase. Reducing the virtual particles in the Higgs-illuminated volume. * Per [original article](https://www.nbcnews.com/news/all/speed-light-may-not-be-constant-physicists-say-flna6C9649533), the reduction of virtual particles in the volume outside of the ship creates a region of "superpermittivity" (better permittivity than $\epsilon\_0$) outside the vessel. * This field remains ahead of and around the ship much like a sonic shockwave. * The vessel and all the local space with it, travel behind the shockwave using ordinary rocket propulsion at ordinary sub-light speeds, but enjoying both an effective mass decrease ($m\_n = m\_0 {{c\_0^2} \over {c\_n^2}}$) and access to absolute velocities higher than $c$ without violating any causality, because the ship never exceeds the speed of light locally. [![enter image description here](https://i.stack.imgur.com/rIMHFm.jpg)](https://i.stack.imgur.com/rIMHFm.jpg) Does this approach work? [Answer] As others pointed out, the premise to your FTL engine arises from a misunderstanding of the article and under the hard-science constraints would not be feasible. You are correct in that the article is proposing that the permittivity and permeability of free space arise from virtual particles. However, it appear there is a misunderstanding of the meaning and implications of virtual particles. ## Virtual Particles and Quantum Field Theory Virtual particles arise as mathematical artifacts which "build", so to speak, an interaction. By summing up the various terms produced by virtual particle - particle interactions (whose quantities are determined by the likelihood of the virtual interaction), an interaction can be described at the chosen level within a perturbation expansion. To formulate a perturbative expansion within quantum field theory, an energy scale (soft over hard) needs to be identified. This places restriction on the energy range over which the theory is applied to ensure a finite number of interactions at each level of the expansion, which is important for convergence. The particles in the interaction are cast as excited states of an underlying fundamental field which allows for the application of perturbation theory (which relies on corrections to a known ground state solution). For a given energy scale, all possible particle interactions needs to be expressible. Symmetries (and their breaking) identify which particles should be taken into account. The above very simplistic summary is not meant to describe how to do quantum field theory (even a simplistic overview takes a whole book), instead I tried to highlight the most general factors which must be considered when applying the theory, which are relevant to the referenced papers. So in the papers, the authors consider quantum fluctuations of elementary fermions (the quarks and leptons). This is because a vacuum would represent the "ground state" of quantum field theory. The vacuum speed of photons (speed of light) is linked to the vacuum constants, which in turn are intimately connected to charge symmetry and to the ground state (the vacuum). Thus, the authors employ an elementary model to determine a predicted range of flight time fluctuations if photon propagation is described in terms of interactions via fermion-antifermion virtual pairs. It is important to note that the paradigm for all of this is quantum field theory. In this light, it should be understood that the interactions are effective and not at all to be interpreted as physical. This is explicitly stated in the Leuchs et al. paper, from which I quote: "Indeed, from this picture, the vacuum can be understood as an effective medium". This does not mean that we throw away our physics textbooks and rewrite them with references to the "luminiferous aether" and delete any reference to the vacuum of space. Instead, this would represent another phenomena which can be explained in terms of quantum field theory. Quantum field theory, at its heart, is a mathematical description. We use terms like virtual particle interactions, but note, the theory implies an infinite number of degrees of freedom (something which is quite obviously not physical nor intended to be viewed as such). The focus on quantum field theory arose historically with the astonishing success of quantum electrodynamics. The theory has also been applied successfully (though not nearly with the same degree of accuracy) to nuclear forces. In a sense, quantum field theory is ab initio (it relies on the most fundamental symmetries and interactions). Yet, the names we apply to the mathematical entities which compose quantum field theory should not be viewed as physical. After all, the theory relies on a solution which arises as an approximative correction. In other words, we do not think of all square waves as actually being composed of an infinite summation of sine and cosine waves in light of Fourier series. To help with the analogy vs. the physical, consider other mathematical artifacts which are employed in quantum mechanics, the wavefunction for instance. The wavefunction yields the probability of various observables for a given quantum state, and is a fundamental component of quantum theory. However, we do not think of the world as existing as an endless superposition of all possibilities. Another phenomena is quantum tunneling, yet we don't think that particles physically "drill through" non-physical potentials. These are just phenomena which have relatable analogies. ## The FTL Drive A theory or model should only be applied where applicable and application of quantum field theory must come with justification based upon the energy scale and symmetries involved. Lets go through your FTL drive point by point: * Emitters around the bow and sides of the vessel produce colliding ion streams with sufficient collision energy to create Higgs bosons. A Higgs boson has a mass-energy of 125 GeV! For comparison, the chiral symmetry breaking scale is on the order of 1 GeV; that is to say the hadrons in the emitter would have been disintegrated long before a Higgs boson is produced. * The Higgs fluctuations reduce the coupling between charge and mass, "de-massing" (reference) even virtual particles The virtual particles at play here are going to arise from whatever interactions are taking place during the creation or decay of the Higgs particle; they are not going to be the same as the ones described in the paper because the energy scale is very different. Recall the paper describes a vacuum and this situation is most certainly not approximated by a vacuum due to the degrees of freedom present. Also, what is meant by "Higgs fluctuations reduce the coupling between charge and mass"? Higgs bosons are very massive and have no charge. * The "de-massed" virtual particles keep their kinetic energy, meaning their velocity would increase. Reducing the virtual particles in the Higgs-illuminated volume. Particle Kinetic energy is not typically described with the classical relationship of velocity, instead it is described through momenta. This situation is complicated by the fact that virtual particles do not obey the dispersion relationship. Also, I'm not sure what is meant by this in connection with either the paper, the Higgs Boson or the Higgs field. As concerns the paper, photons are already massless, so I'm not sure how having a massless ship would remedy the situation. Virtual particles do not have mass in the same way as particles (see the comment in the paragraph above). As concerns the Higgs boson, they would not create a massless field that I'm aware of from the theory (I could not find any scientific paper which references "unmassing" or "demassing", or any reference thereto outside of pop or fringe publications). The Higgs boson appears due to symmetry breaking, for analogy see the pion triplet. The pion is the mediator of the nuclear force on the nuclear energy scale, their existence does not make the nuclear force disappear but rather they become the mediators of the force. My understanding is that the Higgs bosons would do the same for the Higgs field by analogy (both are Goldstone bosons) at the appropriate energy scale. The existence of the Higgs boson is significant in that it confirmed portions of the Higgs field theory, not because it can be used to zap particles into a massless state. * Per original article, the reduction of virtual particles in the volume outside of the ship creates a region of "superpermittivity" (better permittivity than ϵ0) outside the vessel. The article in question describes a vacuum calculation. The presence of super massive particles like the Higgs boson already renders the basic assumptions invalid. * This field remains ahead of and around the ship much like a sonic shockwave. What field and how does it remain "ahead and around the ship"? From the previous reference to a "Higgs-illuminated volume" it would appear that the Higgs field is being misunderstood. The "Higgs field" refers to an algebraic symmetry which mathematically describes the Higgs mechanism and not to a visible R3 space field. * The vessel and all the local space with it, travel behind the shockwave using ordinary rocket propulsion at ordinary sub-light speeds, but enjoying both an effective mass decrease and access to absolute velocities higher than c without violating any causality, because the ship never exceeds the speed of light locally. There seems to be a lot of conflating of concepts here. Trish does an excellent job of summarizing the causality issue which would arise. It seems to me like frame-dragging is also being referenced. Unfortunately, the physics doesn't make sense at all. Consider the frame-dragging of "local-space", why would a massless form of particles cause dragging of space-time, which is specifically an effect of mass propagation? Also, as regards causality, since the ship is traveling slower than the speed of light in its own reference frame and faster than the speed of light in all other references frames, there could exist a scenario in which a cause is observed to precede its effect (the very definition of causality violation) [for a quick example consider if you flew your ship in a circle, you'd catch-up to and pass yourself which is absurd paradox, easily resolved with the causality restriction]. [Answer] ### [hard-science](/questions/tagged/hard-science "show questions tagged 'hard-science'") = NO Currently, we describe particles by their speed compared to the speed of light using the [light-cone](https://en.wikipedia.org/wiki/Light_cone): * Light that moves with the speed of light is light-like. The totality of events that create such particles lies on the surface of a cone of past and future, both crossing in the point of "now" (the spectator). Anything on the cone can be seen at the moment. * Events inside the cone can have a causality to one another: Any event has its own light cones, and if another event is in the fututre cone of a past event, then the past event can be the cause of the other one. Likewise, any event that has another event in its past cone, can be caused by it. As an extension: Any movement of an object can only happen upwards inside the light cone. * Anything outside of the cone is defined as "Space-like". That is, particles or events outside of the observable cone (the light cones) exist, but you can not interact with them (yet) and they can not be the cause for events that happen there. Ergo, the butterfly can only cause the storm if enough time has elapsed so the particles could interact and cause the storm pattern. Or in other words: Cause and Effect are not instantaneous. A drive that would force an item to interact with space-like objects - and nothing else is FTL - is prohibited by causality. [Answer] Since it is hard-science then answer is no, it is unreal 1. By current concept "speed of light" is not determined by any constants. It is a fundamental constant c of space-time by itself. Even light does not define this constant. It just happens so that light is traveling with this speed (because it is "massless"). It means that changing $\epsilon\_0$ and/or $\mu\_0$ could not make light traveling faster than c (localy) due to consequences of Theory of Relativity. 2. You are not breaking local casuality, but, since your are not bending space-time, your are breaking "global" casuality. It means that possibility of such ship is still a disproof for Theory of Relativity. 3. Im not expert in quantum field, so this part is not that hard. It is really very little known about actual properties of Higgs field (actually only aproximate mass is known for sure). But there are lots of ion streams in space with ordres higher energy than we achived in accelerators. And no one ever observerd efects of local light speed increase or other consequences of "mass effect". It means that there shuold be some mechanism preventing it. ]
[Question] [ Closed. This question is [off-topic](/help/closed-questions). It is not currently accepting answers. --- This question does not appear to be about worldbuilding, within the scope defined in the [help center](https://worldbuilding.stackexchange.com/help). Closed 3 years ago. [Improve this question](/posts/188971/edit) Looking for a term: I am worldbuilding a government that elects representatives to positions of authority, but those representatives customarily refer day-to-day and big decisions back to the electorate. This happens in a daily meeting that takes place online. Agendas are published twelve hours ahead. Voters are expected to show up informed on the issues they care about, and abstain where they don't care. The meeting provides time for voters to be recognized to ask questions or argue perspectives. A quick vote that isn't binding on the representative, but is usually used as a guide to the final decision, ends each agenda point. Any voter can call for a removal of a representative or a whole administration at larger, monthly events. Is there an existing term for such a form of government? Is it just a representative democracy? [Answer] It's called [direct democracy](https://en.wikipedia.org/wiki/Direct_democracy) > > Direct democracy or pure democracy is a form of democracy in which people decide on policy initiatives directly. This differs from the majority of currently established democracies, which are representative democracies. The theory and practice of direct democracy and participation as its common characteristic was the core of work of many theorists, philosophers, politicians, and social critics, among whom the most important is Jean Jacques Rousseau, John Stuart Mill, and G.D.H. Cole. > > > > > In direct democracy, people decide on policies without any intermediary. Depending on the particular system in use, direct democracy might entail passing executive decisions, the use of sortition, making laws, directly electing or dismissing officials, and conducting trials. > > > [Answer] If the vote by individuals is not binding, then it is just a representative democracy / or republic. Many elected representatives already listen to and are influenced by their constituents. They even have town halls and polls of the electorate. This is not to say they have daily feedback, but that does not constitute an essential difference compared to what you propose. Representatives could gradually change to incorporate an expected daily vote/feedback without changing any rules or structure of the government. ]
[Question] [ So I'm writing a character that cut his face very deep making a big x mark on his face at some point in the past to scare off a couple of thugs. He survived the ordeal, but now it so happens that everyone now and then, all his facial functions shut down mid-speech as a side effect of him cutting up his face. For example He could be sitting in a chair talking to someone and then next thing you know, his head slouches and it looks like he fell asleep. What happened is that, his eyes, mouth and all face muscles shut down for a few seconds to minutes. Then he wakes up. This is a fantasy story, but at least I'd like to cross-check if this can happen in real-life. My question is, Can trauma to the facial nerves cause this kind of thing to happen to a person? [Answer] ### As someone who has had facial nerve paralysis. Not like you've described. Facial nerves are grouped together, so tend to seize up and become restored in groups. [![enter image description here](https://i.stack.imgur.com/pwl3h.png)](https://i.stack.imgur.com/pwl3h.png) The neck, shoulders, and jaw muscles are routed through an entirely different path to those controlling facial expressions. If he damages that nerve on one side, he'll get [Bell's Palsy](https://en.wikipedia.org/wiki/Bell%27s_palsy). I had a swelling at that tiny hole where all the nerves pass together, and gave me 3.5 weeks of: * I was expressionless on one side of my face. * I couldn't shut my left eye. * Couldn't blink, so the eye suffered. * Couldn't chew food without biting my lips * Couldn't shave cause the skin was never taut. * Couldn't speak clearly. I do still get spasms a few months later. But it's more like "5 unexpected winks" rather than anything that severe. The eye chain recovered enough to shut the eye in 8 days. Was still slurring partially (as the lip ones took the longest to recover) for nearly 4 weeks. Importantly: * Could still speak. It sounded like I had a mouth full of food but could still navigate society. * Could accurately position and move my head. * Could accurately position and focus my eyes. Could follow objects with eyes. * No loss of balance or hearing. * Was fully aware of the world the whole time. To get total muscle seizure on both sides, he'll need to damage 4 places on his face, cutting those yellow lines, or 2 places at the back side of the face where they group together going through that hole. [Answer] You describe an absence seizure. <https://en.wikipedia.org/wiki/Absence_seizure> > > The hallmark of the absence seizures is abrupt and sudden-onset > impairment of consciousness, interruption of ongoing activities, a > blank stare, possibly a brief upward rotation of the eyes. If the > patient is speaking, speech is slowed or interrupted; if walking, they > stand transfixed; if eating, the food will stop on its way to the > mouth. Usually, the patient will be unresponsive when addressed. In > some cases, attacks are aborted when the patient is called. The attack > lasts from a few seconds to half a minute and evaporates as rapidly as > it commenced. Absence seizures generally are not followed by a period > of disorientation or lethargy (post-ictal state), in contrast to the > majority of seizure disorders. > > > Cutting nerves on the face would not produce intermittent symptoms like what you need. Symptoms from damaged nerves on the face would be limited to structures on the face. The person would be completely awake and able to speak. [Answer] Nerve damage due to a physical injury is not intermittent as described in the question. What can be intermittent is a psychological issue that might be related to either the self-inflicted injury itself, or the situation that led the character to cut his own face. Rather than nerve damage (and in fact, he might well have nerve damage, but it would be much more localized, small numb patches, as opposed to whole face or head), what you describe sounds like a sort of hysterical paralysis that might be associated with PTSD, Post-Traumatic Stress Disorder. Of course, most fantasy worlds don't have a diagnosis (never mind treatment) for that disorder, but none the less, it existed long before the modern definition: the "shell shock" of the First World War was a version of PTSD, as was the "thousand yard stare" of the Second, and symptoms that fit were described even in Napoleonic days, though in that time and society it was often labeled as "cowardice under fire." [Answer] As the other answers point out, it's not very plausible that cutting one's self could cause this kind of symptom. At least not on it's own, but you might consider adding in some other factor(s). One idea could be that the character had a latent neurological condition that affects his face muscles in this way but it requires a specific pain stimulus to trigger - which his facial scars occasionally provide. I'm thinking in the realm of conditions like epilepsy where certain stimulus can cause the brain to temporarily malfunction. Although it might seem like a big coincidence for this specific person to have such a condition. Another idea would be to propose the existence of a particular microorganism / disease which has the desired effect and which the character became infected with at the time he cut his face due to the blade being dirty or such. Some real-world diseases / infections can have peculiar and intermittent effects with life-long recurrences, so this doesn't seem like too much of a stretch. Maybe mention a few other people with it so that this one person isn't the only one in the world with it, to make it not feel like a huge coincidence. Though if you want to keep it rare you could still say that the disease only exists in a certain region and only rarely infects. ]
[Question] [ For the fantasy setting I'm working on, for a roleplaying game system, civilizations have stagnated into a 15th century technology and metallurgy level with some deviations to make for more interesting gameplay or story. One thing I am trying to do is make a list of materials available within the setting so I know what can, and can't, be made. I'm also using this to give myself a rough idea of how items made from one material would compare to similar items made from another material. --- In a previous question, someone showed me a [useful chart on Wikipedia](https://en.wikipedia.org/wiki/Timeline_of_chemical_element_discoveries) showing which metals were discovered when. I'm curious about what metals could have been refined using the techniques and knowledge of the 15th century if they simply had access to, and knew about, the ores needed to refine said metals. I am also curious about metals that could be made possible with 15th century alchemy/chemistry knowledge to separate unwanted materials from ore to produce something that can be refined in a traditional smelting furnace, even if such a process is time consuming and expensive. For this question, we're ignoring magic. There are materials that can only be magically obtained, but we're not discussing them in this question. [Answer] ## Specific examples * [Platinum](https://en.wikipedia.org/wiki/Platinum) can be found in native form; so that they could have had platinum in the 1400s if only they had access to native platinum deposits. In real history, platinum was not known to European chemists before the 18th century because there are no significant native platinum deposits in Europe; but there are such deposits in the Americas. * [Cobalt](https://en.wikipedia.org/wiki/Cobalt) can be extracted from ore using reduction with carbon in a [blast furnace](https://en.wikipedia.org/wiki/Blast_furnace). In real history cobalt was discovered in the 18th century, but a very lucky alchemist could have obtained it in the 15th. * [Nickel](https://en.wikipedia.org/wiki/Nickel), [molybdenum](https://en.wikipedia.org/wiki/Molybdenum) and [manganese](https://en.wikipedia.org/wiki/Manganese) should have been available in the 15th century, but weren't, to the eternal shame of European alchemists. There is nothing special about smelting nickel, molybdenum or manganese; they could have done it, but they didn't, and the world had to wait for the 18th century. * Metallic [chromium](https://en.wikipedia.org/wiki/Chromium) can be smelted from the oxide by heating with charcoal, so that it could have been available in the 15th century if only the alchemists had access to [crocoite](https://en.wikipedia.org/wiki/Crocoite). * Sodium, potassium and aluminum metals cannot be smelted without electrochemistry. (OK, aluminum can be extracted without electrochemistry provided one has access to metallic potassium; which doesn't help.) * Extracting [magnesium](https://en.wikipedia.org/wiki/Magnesium) in metallic form requires either very high temperatures or electrochemistry, both of which were utterly unavailable to 15th century alchemists. * [Barium](https://en.wikipedia.org/wiki/Barium) and [calcium](https://en.wikipedia.org/wiki/Calcium) are highly reactive metals, and I'm afraid that obtaining them in metallic form is way beyond the abilities of 15th century alchemists. (Note that the Wikipedia table mentioned in the question lists the date when their existence was first proven, not the date when they were first obtained in metallic form, which was much later.) ## General considerations * Before modern chemistry, a metal had a chance of being known in its metallic form only if it was found in its native state, or if it could be smelted from its oxide (or sulfide) using carbon (or carbon monoxide). No other smelting method was available. Look at the chemical [reactivity series](https://en.wikipedia.org/wiki/Reactivity_series). Metals more reactive than titanium cannot be smelted from oxides using carbon, so that there is no way for them to be available in metallic form before modern chemistry. * Before the middle of the 17th century chemistry was almost purely qualitative. Chemists used very very little quantitative measurements; there was no such thing as a temperature scale, a density scale, a hardness scale and so on. Two substances were recognized as being different only if they very conspicuously different using purely qualitative observations. An example: it is not hard to smelt molybdenum once you know that [molybdena](https://en.wikipedia.org/wiki/Molybdenite) is neither graphite nor [galena](https://en.wikipedia.org/wiki/Galena). But how could they know that molybdena is not [graphite](https://en.wikipedia.org/wiki/Graphite)? It looks like graphite. It leaves a dark mark on paper like graphite. It can be used as a solid lubricant like graphite. It was actually used interchangeably with graphite, and nobody noticed anything out of the ordinary. (Fun factoid: those three substances were not really distinguished before the modern age. They thought that graphite was some sort of lead ore; that's why we speak of the "lead" of a pencil. No, pencils never contained the metal lead.) * Before the second half of the 17th century chemistry had no theoretical basis whatsoever. (And the theoretical basis developed in the second half of the 17th century was [fundamentally wrong](https://en.wikipedia.org/wiki/Phlogiston_theory) anyway.) This is critical: in the absence of a theoretical basis chemists had no idea how to organize their knowledge. All chemical knowledge was an unsorted, unordered, chaotic mass of anecdotes. It is very hard to make progress when your field of study consists of myriads of anecdotes, with no stable quantitative measurements, with no ordering principles, with no commonly agreed terminology. * Indeed, because chemistry was a chaotic collection of purely qualitative anecdotes, it is sometimes hard to say exactly was counts as a metal being available. For example, there are Ancient Egyptian artifacts which contain a (natural) alloy of gold with small amounts of platinum; but we don't consider platinum being available before the modern age, because the Ancient Egyptians themselves were not aware that there was anything amiss with their gold. Some samples of Indian [Wootz steel](https://en.wikipedia.org/wiki/Wootz_steel) (imported in Europe as "Damascus" steel, because it came through Damascus and the Europeans had no idea where it ultimately came from) contain some small amounts of vanadium; but nobody knew what was that made that "iron" so desirable. [Answer] I think there are two main methods for refining. Heat, and Electricity. Both of these could be produced magically and allow metallurgical development more easily. For heat, the issue is that you often need a lot more heat than can be developed through a wood or charcoal fire. Like 4000°F instead of 2000°F. Magical flame could allow you to smelt and work these metals. Some metals need less heat. Zinc for instance will evaporate in a charcoal fire. So the control of the temperature is what is really important. Another means of smelting is electrolytically, for instance of Aluminium. Magically produced electrical power could do this. In both cases, we are probably talking about small batches (grams to ounces), but it could be a small batch every day. (I actually first considered this when I got introduced to the Runequest roll playing system. Everyone could have some magic, so why not the local blacksmith?) ]
[Question] [ I've seen a lot of articles and even questions here which talk about how long modern human artifacts will last. Mostly it seems to boil down to modern materials not having great longevity, though stone has lasted thousands of years. I gather metal doesn't tend to last because it tends to react and corrode. What I'm wondering is this. Without invoking handwavium super materials, it is plausible within known chemistry to engineer materials that could last for many millions of years? Could some synthetic form of stone resist weathering for extreme periods of time? Could some metal alloy? Would being buried under ground held or hinder this? Space and vacuum probably make this easy, no? Obviously we don't yet know of such things, so there is no specific material to be pointed to, but is the possibility plausible? I don't mind leaving the material vague, but I'd feel better about it if I knew it wasn't completely nonsensical. I'm working on really old alien artifacts and ruins and am trying to gauge what could still be around and where, 60+ million years later. Edit: Noticing a couple calls for clarification. In the setting I'm working on, a bunch of aliens got wiped out over 60 millions ago. There might be some intact stuff here and there capable of maintaining itself, but mostly I'm wondering how feasible it is for them to have built tools, buildings, vehicles, etc out of materials that could survive to the present day. Buried, underwater, or out in the open, without having to invoke unobtanium/handwavium materials. Is it plausible that a material based on chemical matter can be that durable? [Answer] TL:DR Absolutely, not even an issue. There will undoubtedly be artifacts that are discernible from this alien civilization, after just a short period of time of only 60 million years. However, it depends on whether you want them to functionally survive, or just survive so that they are discernible. In pure cosmological terms, 60 million years is just a [drop in the bucket](https://en.wikipedia.org/wiki/Oldest_dated_rocks). > > The oldest dated rocks formed on Earth, as an aggregate of minerals > that have not been subsequently broken down by erosion or melted, are > more than 4 billion years old, formed during the Hadean Eon of Earth's > geological history. Meteorites that were formed in other solar systems > can pre-date the Earth. Particles from the Murchison meteorite were > dated in January 2020 to be 7 billion years old.[2](https://www.usatoday.com/story/news/nation/2019/10/24/rise-mammals-trove-66-million-year-old-fossils-discovered/4082963002/) > > > As another poster in another answer has stated, the fossil record on Earth goes back at least that far. See [this](https://www.usatoday.com/story/news/nation/2019/10/24/rise-mammals-trove-66-million-year-old-fossils-discovered/4082963002/), for instance. > > Sixty-six million years ago, the asteroid that wiped out the dinosaurs > also ushered in the age of the mammals – an age that continues to this > day. > > > Scientists have known little about the mammals that survived and > flourished in the years after the asteroid impact. Until now. > > > A study on a recent discovery of thousands of mammal fossils at a > nature preserve near Colorado Springs, Colorado, has shed light on the > little-understood era. > > > So if archeologists on Earth can deduce what happened on Earth 60 million years ago, it is well within conjecture that remnants of a 60 million year old civilization could remain somewhere in the galaxy. Based on the success of our archeologists today, here on Earth, we can say with some confidence: If their function were purely decorative, they could still be discernible and their decorative nature appreciated. If they were unmechanically functional (like a hammer, with no moving parts) their use would certainly still be discernible, and maybe even functional. If they were mechanically functional (like a wheel and axle, a simple machine, or even gears and cogs) their function could be discernible, but they would probably not be functional. If they depended on conducted energy, such as electricity, they would probably be a complete mess, undiscernible. Our electronics have a life much less than even 100 years, before the circuitry degenerates due to molecular and atomic drift. Passing electricity through a material causes all kinds of changes at the atomic level. However, advances in [carbon nanotube technology](https://www.sciencedirect.com/topics/materials-science/carbon-nanotubes) suggests that with continued development, 'electronic' devices could be made from carbon nanotubes that might be discernible, but probably not functional, after that long. We simply do not know yet how stable we can make carbon nanotubes. After all, diamonds, that will last billions of years, are also made from carbon, in a matrix/lattice structure. If carbon nanotubes can be made even close to this stability, 60 million years is but a blink of the eye. It might depend on whether they are used, or dormant, for that length of time. Dormant devices may not degrade, as there is no conducted energy going through them. The problem with our electronics today, is that there is so much use of chemicals and substances that eventually dry out (insulation, heat transfer goo, and dielectrics in capacitors and transformers for instance). Our electronics will probably be discernible in a hundred years (if they are not recycled) but I doubt if they will be functional. Even electrical motors will be iffy after two hundred years of use. Materials such as glass and [diamonds](https://carnegiescience.edu/news/canadian-diamonds-found-be-oldest-earth) will be around for billions of years. So if a diamond were engineered, for instance it was cut or engraved, it would be essentially intact. Decorative and functional objects and artifacts made from glass would also be intact and functional, after only such [a short time](https://www.scientificamerican.com/article/fact-fiction-glass-liquid/). > > A mathematical model shows it would take longer than the universe has > existed for room temperature cathedral glass to rearrange itself to > appear melted. > > > So yes, even after the demise of human civilization, after 60 million years there will still be evidence of our former existence from our artifacts that have survived. It will be much like archeologists sifting through the fossil record of Earth, going back some 60 million years ago, trying to decipher what we were all about, but our existence would certainly be evident. However, functionality will be a completely different issue. But the question does not seem to require functionality, only discernibility. [Answer] ## Fossils We have many, many artifacts that are millions of years old. We have examples of teeth, bones, amber, and shells that are tens or hundreds of millions of years old. If you're just looking for evidence they existed, we have fossil impressions of dinosaur footprints where they happened to walk through mud that was subsequently buried. As far as constructed artifacts go, the oldest stone tools we've found are about [3.3 million years old](https://en.wikipedia.org/wiki/Stone_tool#Pre-Mode_I), about a million years older than the earliest Homo species. Make something out of dense, water-resistant materials like stone and bury it in compacted clays or silt, and it can last millions of years if left undisturbed. As a specific example, if they hadn't largely been excavated in the 18-20th centuries (and assuming they survived any further volcanic eruptions), I'd expect that the burial of Pompeii and Herculaneum by the eruption of Mt. Vesuvius could have resulted in a wealth of Roman-era fossils preserved under all the ash. [Answer] This would give a different spin, but you could go for a machine that repairs itself. Say it only needs a handful of basic materials that are available in its vincinity. The machine would not have general intelligence, just enough to maintain itself and the messages it holds in some form. [Answer] This is currently being developed by the University of Southampton. The technology is called [5D optical data storage](https://en.wikipedia.org/wiki/5D_optical_data_storage). I am no expert in this technology but the researchers claim that it can store information for billions of years: > > The memory crystal is capable of storing up to 360 terabytes worth of data for billions of years. The concept was experimentally demonstrated in 2013. > > > The technology is being developed by Hitachi and Microsoft. [Answer] It depends the material. At time spans of millions of years, half lives of common elements can become important and this is a nuclear reaction, not a chemical or mechanical one and so progresses even if the material is otherwise chemically protected or non-reactive and mechanically protected. This is part of the reason you can't just freeze a person in cryostasis indefinitely even if it somehow stops aging 100% because without biological functions and nutrients to cycle through and repair the body, the elements that constitute the body decay into other elements over a long enough period of time. The more something relies on things being exactly the element it is supposed to be, the more sensitive it will be to these changes. ]
[Question] [ I'm not a fan of the word "handwaving" it just makes me sound like I'm bullshitting something I want into my story with various excuses. Essentially I want to have all of the world's governments and societies to sport more intrigue for firearms. Many real-life firearm prototypes were created, but never saw the light of day in the field of battle, a much more pro-gun world would be my way of including guns like the Pancor Jackhammer, Sunngård, and the Triple Action Thunder as commonly occurring armaments. These weapons may have been overlooked in real-life, but in this fictional reality they were adopted into use. I'm thinking the divergence could occur at some point in the early 20th century prior to World War II, since full-auto firearms really began to pick up steam around this time. This was also the point irl where everyone everywhere was attempting all sorts of odd concepts like pen guns, pistols that could literally fit in the palm of your hand, and dart guns made for use by assassins. [Answer] Decentralization and distributism In many ways the modern economy of most of the world favors ever-larger corporations in a "winner takes all" competition for the last penny. Products become virtually the same, even from different companies, because the basis of competition is agreed on by all, regulated by informal things like trade magazines, reviews, and the training of the industry's employees. Consider another industry, the auto industry: every major manufacturer has almost identical car models, the same sizes, the same categories, the same price points. You can pick any Toyota or any Hyundai and say "this is their equivalent of Ford's \_\_\_\_\_\_\_\_\_". If you go looking for something unusual, like a full-size truck with a stick shift, you'll find that despite the millions and millions of trucks sold each year, made by manufacturers around the world, not even one company offers even that little variation from the pattern. In my mind, a country of 330 million people could have hundreds of auto manufacturers making different designs that appeal to different audiences, but instead we have maybe ten companies designing vehicles around the "lowest common denominators" that offend the most people the least amount. What I want to see in autos, is what you want to see with firearms: lots more variety. Implicitly, variety means there will be, for any individual, gun designs that he loves, and gun designs that he hates. Instead, we have a number of major manufacturers that all make variations on tried-and-true designs that work best for the majority of people: the "lowest common denominators" that you probably won't hate, but maybe can't love. This homogenization is driven partly by marketing, and partly by the nature of public stock companies to never take risks, and partly by large customers like militaries and police departments. The way you change the world to do it, I think, is to fragment the markets. You could have an economy that outlaws stock corporations, so every corporation is family-owned or a partnership of real people who work together. That would reduce the maximum practical size of a company, so you might have hundreds or thousands of medium-sized firearm manufacturers instead of a dozen or so large ones. Or your world could simply have a lot of smaller countries, higher duties and tariffs, higher transportation costs, or other factors that encourage local areas to have their own independent firearm industries, and discourage multi-national brands. It might also help if your people had more of an entrepreneurial spirit (perhaps they live in a country where "employee" is a less attractive legal status) and where tinkering/engineering skills are more broadly available. This could be America in 10-20 years when 3D printers are cheap children's toys and every real man has a CNC machine in his garage. If people have the skills and tools to make their own firearms, the designs of those firearms may be driven more by fashion and fun than by economic pragmatism. [Answer] ## PEOPLE HAVE TO HATE AND FEAR GUNS LESS: If people around the world are going to love guns more, they need to hate guns less and romanticize a firearms culture. A lot of pushback about guns comes from the horror of war. So I imagine a world where WW1 was fought by traditional, honor-bound rules between rivals that felt war was honorable. Cannons, machine guns, barbed wire, and airplanes were viewed dimly, and governments using them suffered real-world consequences. As such, weapons like the Thompson submachine gun and BAR saw actual use in this war. The attitude was that if a man couldn't carry it, it was unseemly to kill someone with it. Naturally, governments had superior access to advanced guns, so when revolutions happened, they made newer, better small arms for their troops. But the revolutionaries weren't hopelessly outclassed, and also romanticized small arms. All this small arms fighting resulted in less universal devastation in wars like WW2. Assault rifles developed early and perpetuated an image of a man with a gun solving the problems of the world. John Wayne was HUGE. Westerns never stopped being popular. Mobsters were glorified even more, as were the police fighting them. Snipers had bubblegum trading cards in the fifties. Eventually as bigger machine guns and RPGs became more man-portable, they would also be really popular. The range of man-portable deadly weapons would be truly frightening and include generations of flame throwers and the like. Suicide vests might be more common as well. Tons of money and resources would be lavished on man-portable arms development, and probably on advanced body armor as well. With all this romance of insanely lethal small arms, what fool would go out on the street without a gun, when the guy robbing the convenience store was probably carrying enough firepower to level the place? And why have just a pistol, when you could have an advanced gyrojet weapon like in the alternate reality version of Dirty Harry? [Answer] I think for maximum gunphilic madness you need to combine the benefits of DWKraus's and Workerjoe's answers and engineer a timeline where there is both much higher demand for guns and more diversified production. So here goes: For the first point, we need most of the industrialised world to adopt American-Style fetishisation of gun ownership (as of 2018, US citizens owned more guns than the next 25 countries put together, and ownership of civilian firearms per capita there is twice as high as the nearest competitor). So let's say Hitler's streak of outrageous luck holds for another year or two and he successfully occupies the UK and USSR. A decade-long Cold War with the USA follows, in which most of the fighting is done by resistance movements armed and supplied by the Americans. Germany tries to confiscate all civilian firearms but fails and the Nazi Empire collapses, leading to a unipolar world dominated by the USA and a bunch of ex-partisans for whom private gun ownership is a highly emotive symbol of freedom. Consequently, when the world order is rebuilt, the UN Declaration of Human Rights copies the US constitution even more heavily and includes a 2nd-amendment-style right to bear arms, which many countries also incorporate into their domestic constitutions. This ought to secure a greater worldwide market for personal sidearms, but how are we to diversify that market? Let's say that, in the decades after WW2, production is initially still dominated by the big US manufacturers. However, other countries' governments are becoming increasingly concerned about skyrocketing levels of gun violence (for example, if the gun death rate in the UK matches that of the US, it would be 50 times higher than it is in our world). They can't ban gun ownership because that would be an unconstitutional human rights violation, so they try to cut off supply by banning all firearms imports. This helps in the short term, but in the long term domestic production rises to meet the demand, so governments try to drive up prices further by breaking up large firms which can offer economies of scale. Furthermore, a legal arms race ensues as states introduce ever more elaborate regulations in order to limit gun violence without banning ownership, and companies produce ever-weirder designs in order to exploit loopholes in the laws (government's just imposed background checks on anyone bringing firearms to work? Our latest product is technically a pen with incidental ballistic capability!). Eventually, almost every country has its own highly diverse firearms industry consisting of lots of small-scale manufacturers, plus plenty of illicit backyard production. Finally, a few years before the present, the international import ban regime collapses; probably the US gun lobby used its influence to finally get what it wanted in an even more America-centric world. This leads to a brief chaotic period in which the world is awash with the products of hundreds of highly balkanised national firearms industries, and market Darwinism hasn't yet culled off the more outlandish designs. This is the climate in which your story will be set. It ain't going to be pretty. [Answer] While this isn't strictly making guns more accepted by the general populous. In terms of increasing firearms variety & having weird weaponry it would work. A higher prevalence of mercenaries. One of the biggest things that impacts firearms development is military requirements. But there are only a few major militaries, & most are too large to switch service weapons. At the same time mercenary groups would mostly be piggy backing of the supply train of a conventional military & conventional militaries would be used to supplying different equipment to their own. So each unit in a mercenary company would have more fluidity in what they could have. So gun makers would have larger variety of customers & could make more weird things for sale to these mercenaries. ]
[Question] [ A nuclear-WWIII happens, lots of people and animals die. Surviving humans are afterwards forced to either hide out in small survivalist compounds on the surface, or self-sufficient underground bunkers. But, humanity continues on. Here’s my question: Eventually, these people will need to start farming once again- surviving purely off canned food and freeze-dried rations isn’t possible. My question is, what crops would be the best to grow? Criteria * For this question, I mainly want to focus on a specific region, the American Southwest (more specifically, California, Colorado, and Utah) * I want something that is easy to grow, hardy, and calorie and nutrient dense. * Plants that can be used for medicine is also welcome! [Answer] Po-Tay-Toes You can fry 'em, boil 'em, stick 'em in a stew! Depending on your WWIII scenario any of the places you specified can go from "yeah you COULD but potatoes aren't ideal" to "perfect potato weather" land. They're resilient, cheap labor-wise to grow, and have the added bonus of whatever mutant nasties/marauding bands are out there being unable to easily destroy your crop! That was one of the top reasons potatoes took off in Europe. An invading army can burn your wheat field or trample your crops, but it's too much effort to destroy a field of potatoes. Which is why some of the most heavily fought-over areas in the time potatoes were first brought back to Europe are now the same areas whose cultures emphasis the crop. Best of all, they're REAL easy for Suburban Survivor to plant and harvest. Slice up a potato so every "eye" is separate, stick 'em in holes (vary the depth, because you didn't google this beforehand and have to play it by ear) and you're good! Well, good-ish, farming ain't easy! But compared to trying to do the same thing with other staple crops potatoes are a walk in the park. From a dietary standpoint they're calorie dense, and have a surprising amount of other things like protein and basic vitamins/minerals, though not 100% of those required for a healthy diet. But as a staple crop they're a great calorie-filler. Also they're readily available in the areas you're looking to have your story in. Sure there are some foodstuffs that might be better, but what are the odds Joe Nuclear Holocaust Survivor has some esoteric south-pacific or African plant to hand in quantities to feed his group of survivors after a single harvest? Sure he might have some in his garden, but if you need multiple uneaten harvests to have enough crop to start feeding 100 people, and you have a 100 person settlement, you don't have the basis of a staple crop. Many other plants are so heavily modified (via GMO or old-school agricultural techniques) that the ones they sell in stores can't actually be used to grow more. But any given grocery store in the US is going to have piles of readily plantable potatoes. The big problem would be you'd run a risk of overdosing yourself with potassium in the long term, as well as certain vitamin and mineral deficiencies if you want an all-potato diet. But as a "staple crop" where your survivors also have limited access to other foods or a good stock of basic vitamins potatoes would see you through! As an aside, you'd 100% want to try and grow more than one thing if it is at ALL possible for you. The odds of a blight, or weather that would effect one crop but not another are REAL bad. If you want an idea of subsistence farming I strongly recommend [THIS BLOG](https://acoup.blog/2020/07/24/collections-bread-how-did-they-make-it-part-i-farmers/) which talks about subsistence farming in the ancient world. Many of the comments and concerns would also be applicable to a post-apocalypse community bent on survival more than productivity. (which I know sounds odd, but trust me it makes sense.) [A quick rundown of potatoey goodness can be found here.](https://www.bbc.com/future/article/20170224-what-food-would-keep-you-alive-the-longest) [Answer] So, what sort of post-apocalytic wasteland are we looking at here? Is this a frozen wasteland, only just starting to emerge from the nuclear winter? Or a burning hot desertified wasteland, with little to no rainfall, a depleted ozone layer and global warming pushed over the edge? Because if it's the former, then might I suggest Durvillaea antarctica, or Southern Bull Kelp (also known as "Rimurapa" by the Maori, "Rimuroa" by the Moriori, "Cochayuyo" by the Quechua and Aymara, and "Collofe" by the Mapuche). This variety is already harvested as a food delicacy in Chilean cuisine. The vast majority of harvesting right now, in the present day, is for the purpose of extracting alginates (agar and carrageenan, both of which would also be very useful in their own right); but it has some of the highest potential yields of any crop, thanks to its extremely fast growth rate, high calorie count, high protein content (enough to replace meat altogether in some native Chilean diets) and an extremely high mineral content (enough to also serve as an extremely useful green fertilizer- albeit also with a very high salt content). Here's a bit of data about the potential harvest available to be reaped: > > The approximate composition (% dry weight) of Durvillaea antartica > (Cham.) is similar for the frond and stipe, being 28% ash, 3% protein, > ca 1% lipid, less than 10% acid-soluble carbohydrate, and 60% > acid-insoluble carbohydrate. The holdfast differed by being 22% ash > and 66% acid-insoluble carbohydrate The energetic level of all 3 > components was ca 13 kJ (/g dry wt). and ca 17 kJ (/g ash-free dry > wt). The relative proportion of the 3 plant components varied little > for plants having stipe diameters ranging from 10 to 40 mm, being ca > 8, 3, and 89 % wet wt, and ca 10, 4, and 86 % kJ, for the holdfast, > stipe, and frond, respectively. Maximal density found in summer was > 471 individual plants/sq m, 226 kg wet wt /sq m, and 457 000 kJ/sq m. > > > To put this in context- most modern countries have cereal yields equivalent to 5 tonnes per ha. From the calories delivered to the food system from cropland hectares, we calculate the number of people who are fed a nutritionally adequate 2700 calorie diet per day, considering 41 crops on 947 million hectares of cropland, and show that present day production of raw plant calories is adequate to feed 10.1 people/ha. In contrast, even when growing in the wild, largely uncultivated (with the study above having taken place in the waters of the Kerguelen Islands, otherwise known as the Desolation Islands, one of the coldest and most desolate places on Earth), Durvillaea antarctica delivers a maximum yield equivalent to 2,260 tonnes per ha. That's a huge difference. Even when we look at the lowest cited figures for average crop yield (Mean standing crop of 123.5 tonnes/ha of shore, with values varying from 47 tonnes/ha on steep shores to 190 tonnes/ha on wide flat reefs, on the East coast of NZ's South Island- with individual plants producing one crop annually, and with at least two years required for new plants to become fertile), that still sounds like it should be more than sufficient to potentially kick-start a post-apocalyptic agricultural base. Going by the nutritional values of the Durvillaea antarctica samples from the Kerguelen Plateau, that'd equate to a yield of 2,002,123 kJ per wet ton. From this we can calculate that the annual wet harvest required to sustain a single adult individual on a 2700kJ per day diet (985,500 calories per annum) would be just over 487kg, translating into a dry harvest of only 75.5kg/annum. I know, it sounds ludicrously small- how can you get 2700kJ from a daily intake of only 207g per day? But when the crop delivers 13kJ/g, the math all adds up. There's no denying that the seaweed has exceptional nutritional value- it's effectively the closest real-life equivalent to Soylent Green in existence, except that it's solid, orange, and has a texture like meat, with harvested Cochayuyo traditionally being preserved by being sun-dried (though it can also be freeze-dried) and then softened by soaking in a dish of water- with the expression "remojar el cochayuyo" (literally, "to soak the cochayuyo") also used in Chilean Spanish to refer to sexual intercourse. [![Chocayuyo, in a Tierra del Fuego marketplace](https://i.stack.imgur.com/Nbq0d.jpg)](https://i.stack.imgur.com/Nbq0d.jpg) With a biannual harvest, using the very lowest estimate of 47 tonnes/ha, that'd still be adequate to feed roughly 48.2 people/ha- that's almost five times the population density which can be sustained by modern day land-based crop harvests, and enough to allow a relatively densely populated fallout shelter to feed its population even with a relatively small amount of arable land (or indeed, none whatsoever, so long as they have a large and enough body of salt-water to grow it in- or even terraces of their own filtered urine, if they were either sufficiently desperate or not squeamish at all). And studies now show that this crop can also be readily used for the relatively cheap, simple and easy production of biofuels such as ethanol, which would doubtless also be critical in a post-apocalyptic environment, fighting to survive through a prolonged nuclear winter period. As for its hardiness and cold-tolerance, well- given that it literally survives, and thrives, along the coastlines of Antarctica, you can't imagine nuclear winter in the American southwest giving it any trouble... [Answer] Prehistoric Agriculture From The Region A lot of Native Americans in the region cultivated crops that were relatively drought-resistant. Here's a nice summary from Wikipedia: <https://en.wikipedia.org/wiki/Agriculture_in_the_prehistoric_Southwest> but it's mostly centered around New Mexico and Arizona. These are mostly beans, squash and corn. They've fed societies before in the same conditions and they can do it again. Nuclear Seeds Before there were GMOs there was the Mutation Breeding: [https://en.wikipedia.org/wiki/Mutation\_breeding#:~:text=Mutation%20breeding%2C%20sometimes%20referred%20to,mutagenic%20plants%20or%20mutagenic%20seeds](https://en.wikipedia.org/wiki/Mutation_breeding#:%7E:text=Mutation%20breeding%2C%20sometimes%20referred%20to,mutagenic%20plants%20or%20mutagenic%20seeds). You just exposed a field of plants to lots radiation and checked to see if anything useful came out of it. The 50s were wild. Since you had a lot of radiation flying around you could include a brand new variety of food accidentally made the same way. ]
[Question] [ These humanoids would be about 13cm tall. Is there anything preventing them from mounting rats with proper training and a customized saddle? [Answer] # In theory with time and training Wild animals need to be domesticated to be used as beasts of burden. Fortunately, rats are very trainable. > > Domesticated rats are very gentle and playful creatures. Like a pet > dog, a pet rat can learn many tricks and can even respond to its own > name. Pet rats can learn to sit up, fetch, jump through a hoop, come > when called, and even walk on a tightrope. Additionally, rats can be > taught to solve puzzles, run through mazes, and perform tricks. > Training a pet rat is relatively simple and rats respond well to a > food-based reward. ([Source](https://www.thesprucepets.com/how-smart-are-rats-3975140)) > > > Rats can even be trained to operate [tiny cars](https://www.bbc.com/news/world-us-canada-50167812). [![Rat driving a tiny car](https://i.stack.imgur.com/zdpXp.jpg)](https://i.stack.imgur.com/zdpXp.jpg) Unfortunately, being trainable is only one requirement for a beast of burden. You'll also need to breed rats who are used to being actively bossed around by humans, and you'll need the rats to be able to support the weight of a rider. Both of these things will require starting with genetically diverse rats and then selectively breeding those that have the traits you want. The average rat can be very aggressive towards small mammals and they might not be able to carry much weight. Honestly, you'd probably be better off picking a different animal. A 13 cm tall humanoid would have an easier time training and riding a tiny dog rather than a rat. Remember that full-size humans can ride elephants, so an itty bitty pooch wouldn't be much of a challenge. Out of all the tiny dog breeds, you might be most interested in the Cavalier King Charles Spaniel, which [the AKC](https://www.akc.org/dog-breeds/cavalier-king-charles-spaniel/) describes as "the best of two worlds, combining the gentle attentiveness of a toy breed with the verve and athleticism of a sporting spaniel." [![enter image description here](https://i.stack.imgur.com/ESDmp.jpg)](https://i.stack.imgur.com/ESDmp.jpg) [Answer] I would say it is very much possible to train domesticated rats as mounts, and as Andrew suggests in his answer it might even be possible to breed them to be able to carry the weight of a tiny human. However the main reason I don't think it will work is a rats gait. They hop along rather than walk, as most rodents do. If you rode them it would be like riding a mechanical bull rather than a horse. With most common mounted beasts, like horses, camels, even ostriches, the back stays fairly straight and stable. With some training you can adjust your body weight to go along with the motion and ride comfortably. Being jolted up in the air, and then slammed down to the back of your mount with every single leap would get exhausting quickly, and to be honest I'd sooner pick a hedgehog than a rat. ]
[Question] [ Project Sampson was designed to create super-soldiers. CRISPR was used to release the limiters on muscles, allowing soldiers to access incredible strength. Of course, initial testing went poorly. Potential super-soliders threw out their backs, over-strained their bodies, and inflicted many other serious injuries on themselves. As people became more cautious with how to use their strength, and the project leads used gorilla DNA\* to improve their bodies ability to handle the strength, things improved. Once an individual had gotten used to their strength, and their body had adapted to outputting on that level without dying, I imagine these super soldiers would be able to pick up and toss a car rather casually. Could this work? Could limiters be released on the body this easily? Are there any other downsides to this I haven't considered? \due to the differences in development this would require, this genetic change was made before birth, as opposed to the other one which would be done on adult humans less likely to accidentally kill themselves. [Answer] No... because there are* no limiters on human strength, at least not enough that removing them would produce super-soldiers. Top athletes and highly trained soldiers would have been trained to ignore the barriers of pain that ordinary people would not normally cross, so that's about the greatest effect that might be achieved - on an ordinary person, and even then, it would be a bit disappointing, as without training, even maximal exertion would be less than that of a trained person. The problem here is the apocryphal stories of hysterical strength, with people lifting cars and tractors in order to rescue a loved one, but on further examination, they aren't lifting the full weight, but taking advantage of leverage, sprung suspensions or tyre inflation to move a heavy object far enough to extract a trapped person... but that person wasn't pinned by the vehicle's full weight either. As for genetically engineering an adult human... that isn't going to work either. Gorillas achieve their strength through both greater muscle mass and greater leverage, at the cost of being able to flex their limbs more slowly than a human. It may be possible to engineer in a gene to increase muscle mass, but it isn't going to get you super-soldiers, just body builders. As for moving bone-muscle attachment points... that isn't going to happen, and if it could, the military wouldn't want it, as it would make the subject slower. If you did manage to splice in gorilla genes to increase muscle mass, it would likely end in disaster, as the subject's immune system started attacking the unfamiliar muscles with gorilla genetic markers on their surfaces. Finally, genetic changes would be made with a virus, not a bacterium. [Answer] Just because you cant feel pain doesn't mean your muscles wont tear; just means you cant feel it. Superhuman strength is an impossibility without two other factors 1. Superhuman durability, the ability of bones, joints, soft tissues and muscles to exert without breaking under the duress. 2. Superhuman or an external energy source outsite metabolism. Lifting one ton of weight requires one ton of Force. A bricklayer can lift a ton of bricks, over time, one or two bricks at a time, over the span of a given time. A man exercising; will burn 700 calories by bench pressing a hundred pounds a hundred times over the span of probably an hour..........to lift the equivalent (10,000 pounds) he would have to burn all those calories instantly. At 700 calories per second a functioning Superstrong person would have to impossibly consume 42,000 calories (35 pounds of pasta) for a minutes worth of strength. [Answer] # A gorilla becomes a gorilla during gestation [Organogenesis](https://en.wikipedia.org/wiki/Organogenesis) is the process that causes internal organs to form. Things like bones, and muscles, and where the muscles attach, and all that stuff? Those are all built during organogenesis. Once that process is done, it is done. If humans, like geckoes, could regrow detached body parts, it might be possible to use genetic engineering on an adult and make meaningful changes to a grown person's body plan. If you're willing to put up with regrowing all the person's limbs. But we don't. Once our parts are fully formed, that's that. Genetic engineering to give someone genes to build the body plan of a gorilla will only do something if the person is an embryo at the time. Once they've grown up, those genes don't do anything anymore. In other words, the answer is no. CRISPR by itself is not enough. People would have to be engineered in the womb, creating newtype humans that might be customizable via CRISPR. Doing things like that is way beyond what CRISPR can do. [Answer] CRISPR is just one potential way to alter the human genome. So there are really two questions here: * Could alteration of the human genome (by whatever means) produce the supersoldier you describe? * Would it have to be a [germline](https://en.wikipedia.org/wiki/Germline_mutation) alteration or could it be done to an adult specimen? For the second point, I agree that this sounds even more iffy than the first. Body and skeleton shape, attachment points of muscles, etc. would already be set. For the first point, probably, but getting it right would require lots of trial and error. There have been almost [fully synthetic lifeforms](https://en.wikipedia.org/wiki/Synthetic_biology#Synthetic_life), but so far only on very primitive examples. There is no reason why there couldn't be a synthetic lifeform with the intelligence of a human and the strength of a gorilla or an elephant. [Answer] There has been some work done on this field already - at least with regards to animals. Scientists have identified one single gene which acts as an arbiter of muscle mass in mammals (the myostatin gene). This gene has been identified in cattle but humans share it with them and other mammals. Together with another regulatory gene called follistatin scientists have basically pinned down the genetics of muscle mass. So in theory you could select the variant of both genes that maximized muscle mass on a human frame while minimizing adverse side effects and insert it into human embryos to produce Olympic class weight lifters on demand. A note of warning there is an upper limit to how much you can alter the gene and increase muscle mass without adverse side effects appearing - look up 'over muscled' cows - Belgium Blues and other animals where the gene has been tinkered with to see a list of adverse side effects. Go to far and your soldiers will not thank you. Another word of caution. Strength, while obviously useful to a soldier is only one of a number of attributes that make for an effective fighter. Indeed physical strength is NOT the most most important element in a good soldier by any means. More important are factors relating to psychological and physiological resilience/endurance. The genetics behind these factors are vastly more complex and much less understood than those of mere physical strength. It does you no good to have a 'super soldier' who can repeatedly bench press 100 kilos for hours on end with ease but who have sub optimal physical and psychological endurance. Ignore these elements and you could end up with super strong soldiers who crumble under pressure due to PTSD and/or lack of rest. Reflexes and intelligence are also assets to take into consideration and again the genetics behind these issues are not yet understood. Lastly remember your extraordinarily well trained and expensive super soldier can still be killed by a half starved, poorly trained, conscripted peasant armed with a crappy rifle. He might kill 10 of the enemy first but he can be killed. War cemeteries are full of 'elite' soldiers. [Answer] If CRISPR is being used then there's really no need for the middle man as you could just as likely bio hack our cells to produce the compound. plus bacteria that don't destroy our cells tend to not thrive inside the human body and if they do need to cause an infection to live then there's no guarantee the patient will survive the infection, even mild ones can get out of hand in extreme cases, especially the harsh conditions of war. Not to mention that removing the limiting factor from muscles just means we won't be able to tell when we've over exerted ourselves and caused damage to our muscle fibers, sure an average human can lift a bus and they have been reported to do so when filled with adrenaline to do something like save a baby but the follow up on such stories is often the user of their "full potential" dying or ending up with crazy amounts of muscle damage and needing extensive care. [Answer] Theoretically you could edit genes in such a way that you have incredible physical specimens. No gorilla genes required. For strength, at least half of it is attributable to muscle size and the myostatin gene can be suppressed in this scenario. Myostatin keeps muscle growth controlled and by suppressing it muscle growth is crazy. Consider the Belgian Blue Cow or the Bully Whippet as animal examples of this. For muscle endurance, having your muscles comprised predominantly of type I slow twitch muscle fibers is what separates elite athletes from regular people (along with training of course). Now this negatively impact strength, but given all the extra muscle that be gained by suppressing myostatin should offset that and then some. These two modifications alone would result in humans capable of much more than what we would currently expect. Maybe you could modify height in certain divisions to have men with truly monstrous strength. Maybe you could modify some to be shorter and much more agile. You’re in the driver’s seat, gene editing has the potential to do these things. Adults stand to benefit very little, but an embryo could be changed in whatever characteristics that scientists in your story have isolated genes for. [Answer] Yes you can remove the limitations, but why would you? Humans do limit their muscle power, but they can already release these limitations in fight or flight mode. This is what happens when you hear about a parent lifting one end of a car to get their child out from under it. The thing about these limitations is that they are there for a good reason. Using your full strength means you damage you muscles, your tendons, your bones, potentially rip the tendon anchorpoints out along with bone chuncks. Using the full range of strength for just a few seconds will cause tremendous damage to yourself, and you can expect weeks if not months of recovery afterwards. The extra strength by using Gorilla DNA is also a drawback for supersoldiers. While superstrength is often one of the most basic of superpowers it also comes with limitations to endurance. A Silverback gorilla simply wont be doing a day-long march and still have the strength to do any combat, let alone throw a car. You might use them for short engagements but to make their strength worth it is going to be hard. And even a Silverback Gorilla with its limitations removed is going to have a hard time throwing cars. He might lift them, but throwing is another matter alltogether. I would focus my supersoldiers on endurance and speed. For strength I would look into powered exeskeletons to carry heavier weapons and armor rather than biological improvements, assuming you still think you need it. But aside from carrying your basic gear with you there is little reason to become even stronger. You want your soldier to carry a bunch of armor and gear for the better part of a day, not carry very heavy equipment for two hours and then rest the rest of the day. [Answer] The premise of your question arises from a false myth on the level of "humans only use 10% of their brain power" Lift heavy weights>get stronger> get old>get weaker>die Humans have no limiters, the only thing limiting human strength is time. After you get older, strength is gonna decrease, unless you take medically prescribed steroids. To remove the limit you need immortality. Motor unit recruit doesn't happen all at once not because otherwise it would injure us, injuries do not work that way. Let me give an example to you, you already have enough strength in your arms to pull your finger and break it. You already have enough strength in your leg to kick a wall and break your bones...you already have enough strength in your arms to break your neck... What is the likehood of you doing any of that? Motor unit recruitment doesn't happen at 100% because our nervous systems do not have the energy to do so, and if they did it would burn all the muscle at once. Muscle is consumed slowly with work, using 100% of a muscle at once would mean that the muscle instantly got completely wasted and can't be used. People get sore legs from squats and have difficulties walking and standing up, imagine if they used the entire muscles ...they would not even be able to move at all the legs until they recovered....they would be paralized for days. Muscle recovery can take between weeks to Months and the only reason we are still able to walk after doing barbell squats is because we have more muscle to consume and use while the already consumed one is recovering. Whats the point of using all your muscle tissue at once if you are gonna remain paralized for weeks and months afterwards? Another example: you do bicep curls, good you just damaged 10% to 20% of your bicep brachii, you still have 80% to use tomorrow and your arm is not paralized, you can still lift a water glass to your mouth to drink. ]
[Question] [ Is is possible or easy to milk a fallow deer, is it a quality milk, and can it be turned into cheese? [Answer] Possible yes Easy no Very few animals are comfortable being milked, even many domesticated animals that have been milked for hundreds of generations are still difficult to milk. (camels, horses). Can they be milked of course it is just a pain in the ass, the animals don't like it and [it is more work](https://www.sciencedirect.com/science/article/abs/pii/S000334720091515X), you will not have factory dairy production with deer. fallow deer milk composition is [similar](https://agris.fao.org/agris-search/search.do?recordID=IT2007600649) to buffalo and sheep milk, so it may even be healthier than cow milk. It is a better source of [calcium and a worse source of iodine](https://www.sciencedirect.com/science/article/abs/pii/S0921448815300109). Any milk can be turned in to cheese, so that is not a problem. Mozzarella is actually water buffalo milk. [Answer] Historically, fallow deer have been domesticated for purposes of milking, and there is continued interest in the species to this day for producing boutique dairy products. While deer are nervous animals, with long-term exposure to and care from humans, it is reasonable to expect that they would be no more difficult to milk than a cow (meaning that they would accept the presence of a familiar human and would allow themselves to be milked), and once accustomed to being milked, in the absence of a fawn, they would likely be no less eager to relieve the pressure and discomfort of full udders at the time that they are regularly milked than cows have been shown to be. However, unlike a cow, the yields would be lower in both quantity per day and total number of productive days per year. ]
[Question] [ I'm writing a series that takes place on an earth-like planet, and I really want there to be two moons, specifically. I want there to be tides, but I don't want them to be so intense that they encompass entire coastal cities. I would prefer them to be in a similar/the same orbital pattern as each other, but as I have literally no understanding of how any of this works, I'm willing to compromise on that for the sake of realism, if possible. If it helps at all, the visual I'm after is inspired by the ps2 game Dark Cloud, in which there are two moons. [![game art featuring the two moons](https://i.stack.imgur.com/3XKVU.jpg)](https://i.stack.imgur.com/3XKVU.jpg) How can I get this effect? Is it possible? What should I bear in mind with this? Hypothetically, if the moons were the same size and density (or at least comparable) to our Luna, how would that affect the tides, and is there anything else in particular it could affect? How could they end up in orbit, theoretically, and how long would they have had to be there to become tidally locked (at least one of them)? Would they have to be made of something different to appear as a different color, or would that be more down to atmospheric gases? I apologize ahead of time, I'm in no way an expert on matters of space, but I am trying! Thank you for your time and help! [Answer] It's probably not possible for two Luna-like moons to exist around an Earthlike planet. There are two major reasons why: formation and orbital dynamics. There are two main ways that moons form. The first is similar to how planets themselves form. When the solar system was young, the material that would become the planets was essentially a huge disc of gas and dust. These small particles drew together over time, forming small rocks that gradually accreted into distinct bands. As those bands coalesced, they formed larger and larger bodies, eventually becoming planets. Smaller planets "sweep up" the lingering gas and dust that remains near their orbits, but for the largest planets like Jupiter, there's enough remaining material for it to undergo the same process and form [new rocky bodies](https://en.wikipedia.org/wiki/Ganymede_(moon)#Origin_and_evolution). The second way moons occur is by capture. Asteroids and other small material that passes near a planet may be caught in its gravity well and drawn into a stable orbit. This may be how [Mars's moons](https://en.wikipedia.org/wiki/Moons_of_Mars#Origin) came to be; it's also a common origin for small moons of gas giants. Neither of these explanations works for Earth's moon, though; among other things, it's far too large. The leading hypothesis of Luna's formation is the [giant-impact hypothesis](https://en.wikipedia.org/wiki/Giant-impact_hypothesis), which posits a collision between a smaller Earth and a Mars-like body. This would result in the smaller body and much of the Earth being liquefied, with the resulting magma either falling back onto Earth or remaining in orbit. Over time, the remnants in orbit then coalesced into the moon. (Although the hypothesis itself is well-supported, the exact details of the impact and later stages are the subject of a lot of speculation and modeling.) It's not clear to me whether it's possible for the cloud of debris to permanently become two distinct moons, but it seems unlikely; because of their orbital characteristics, they'd be too close together and would tend to merge together. If an Earthlike planet did have two large moons, it would be hard-pressed to keep them. Large orbiting bodies will tend to interfere with one another's orbits, which usually results in one of them being pushed too far away from the planet (and escaping from orbit) or too close (and disintegrating). This would also prevent them from being tidally locked to Earth, which requires a relatively stable orbit over a fairly long period of time. A stable orbit involving three bodies similar in size, like Earth and two Luna-like moons, is extremely unlikely; combined with the formation problems, this means it would almost certainly be of artificial origin. Plenty of sci-fi stories have planets and moons shaped into artificial orbits by sufficiently advanced aliens for practical or aesthetic reasons, or just for the heck of it. In terms of Earth tides, the effects would be difficult to predict; it depends a lot on the specific orbits of the moons. If they have the same orbital period and are in the same part of the sky, their effects on tides will combine and you'll have much more powerful tides to deal with. (Also, they'll probably eventually run into each other.) In the more likely case that their orbital periods and/or inclinations vary, you'll have a partial interference pattern; similar to how [spring and neap tides](https://en.wikipedia.org/wiki/Tide#Range_variation:_springs_and_neaps) are driven by the Sun's tidal influence being out of sync with the moon's, your moon tides would sometimes line up (creating very high tides followed by very low tides) and sometimes interfere (creating relatively flat tides all day long). A couple of other options spring to mind. Plenty of stories are set on the large moons of gas giants, and although we haven't found one yet (our existing methods of detecting planets around other stars aren't sensitive enough to pick up their moons), there's no reason why one couldn't exist at a habitable distance from its star. The sky on a moon like Europa [would be pretty dramatic](https://www.space.com/28705-how-to-live-on-europa.html), featuring several other moons that would appear roughly the size of Earth's, plus the large disc of the gas giant itself. Tidal effects would be dominated by the gas giant, of course, but you would see a noticeable resonance from the other moons, more similar to spring tides than the huge swings of a smaller planet with multiple moons. On the other extreme, you could have an Earthlike planet with multiple smaller moons. Mars's two moons are [visible from its surface](https://www.space.com/28403-astronauts-mars-skywatching-phobos-deimos.html), and though Deimos is rather small and unimpressive Phobos at least is clearly visible and rather dramatic to look at (because of its fast orbit, it goes through a full set of moon phases about once a Martian day). There's no reason why a planet couldn't be host to even more small, captured moons, and though this also wouldn't be stable in the long run, it could provide pretty spectacular viewing for a few thousand years while it lasts. Tides from such small bodies would be minimal; the sun's influence would probably be the most significant. A final note on color: the color of a stellar body is indeed mainly determined by its composition (or its atmosphere, if it has one). Mars is a famous example; its red coloration comes directly from the iron-oxide-heavy composition of its soil. [Io](https://en.wikipedia.org/wiki/Io_(moon)) is also well-known for having a yellow coloration based mainly on sulfur. Europa's surface of water ice is similar in color to Luna's gray but is over five times brighter. And so on. [Answer] Two moons would make the tides more intense, not less. Also more complex. Here on earth we have "spring tides" and "neap tides" -- these are driven by the sun but there is enough of a difference that classical Greeks noticed them even though the Mediterranean is not strongly tidal. The reason the sun is of lesser effect despite its vastly greater size is that it is farther away. To introduce another moon, even one much farther away than ours, would make the tides the sum of three celestial bodies. This would produce neap tides much lower, and spring tides much higher, than on our planet. If you want to decrease tides, you could look at variation in tides on Earth, which is quite substantial, and use the geography, either for the region you want or all over the planet. If that's not feasible, increasing the distance between the planet and the moon would decrease them. [Answer] This is a fascinating question! As you mentioned, the effect on the tides would be most obvious characteristic, and the only way I can think of reducing them so as not to encompass cities would be to make the second moon smaller, and to move the second moon far away. Newton's [law of gravitation](https://en.wikipedia.org/wiki/Newton%27s_law_of_universal_gravitation#Modern_form) says that the gravitational force exerted by a moon on a planet is given by [![Newton's law of gravitation equation](https://i.stack.imgur.com/F6ZUD.png)](https://i.stack.imgur.com/F6ZUD.png) So, basically the force of gravity is proportional to the size of earth (m1), the size of the moon (m2), and square of the orbit radius (r). If you move the second moon 4 times as far away, you would have a gravitational force 16 times less. So in theory you can still have a beautiful moon of the same size and density in your landscape photography without having it destroy cities by just moving it farther away. You could also reduce its mass (But i believe you want to keep the same size/density). Also, according to the wikipedia article for the [moons of mars](https://en.wikipedia.org/wiki/Moons_of_Mars#Characteristics), there could be some other curious consequences: 1. If the moon orbits quite closely, your second moon could look smaller near the planetary poles and bigger near the equator, like a bright star or planet. 2. You may have more frequent lunar eclipses if the second moon is close enough. It may often block the sun. 3. Depending on the direction of orbit, a smaller moon could rise, set, and rise again in less than a day (Eg., 11 hours for Phobos)., or a larger moon could take 3 days to set. 4. The planet also exerts a gravitational pull on the moon, so at some point in the future, a smaller, closer, moon could be broken up by the tidal forces, and the fragments could crash into the planets, causing huge craters that can affect the surface of the planet. This could be a fun apocalyptic prophecy maybe? Hope that is of some use! Such a great question! [Answer] Cadence's answer is very good, but it might leave you with the the sense that you can't get away with anything interesting. I think there are definitely some good possibilities. You want to imagine two moons with approximately circular orbits that have significantly different radii. If the radii are too similar, the system tends to be unstable. One way to have a stable system is for the moons to be in resonance. Do a search for "orbital resonance", and also read about the Galilean moons of Jupiter. A possible scenario is one where the inner moon goes around twice for every time the outer moon goes around once. Edited to add that I also like M. A. Golding's answer, and the others aren't bad either. But I definitely still think you should consider having them be in resonant orbits. Also I will add that you might have fun reading about theories of how Uranus and Neptune got their moons. Captures were quite common out there. One thing to realize about capturing a moon is that, without friction, it's hard for gravity to really "capture" something. Things speed up as they get closer, and slow down as they get farther away, so in the end they are moving just as fast but heading away from the planet. The way captures do happen is, either, (a) there is still a thick dust cloud that slows the body down, or (b) there is a third body in the system that maybe gets kicked into a higher orbit, slowing down the new body enough to capture it. But this is all just background. I think you have some flexibility. Cadence is right that it is hard to imagine how we could end up with two Luna-sized moons. But what you really want is for them to be big in the sky and affect the tides. A second moon that is significantly smaller and significantly closer could still look nice and big in the sky. In my judgment, not enough earthlike planets have been observed to rule out unexpected moon-acquisition scenarios. Really, the inner solar system planets are the only examples we have where we know what moons are present. You can be more confident that the orbits can't be too close together, or the moon much farther away than ours, because the orbital dynamics make it unstable. [Answer] You can get rid of the tidal problem by making the two moon co-orbit, the second moon in a [Trojan](https://en.wikipedia.org/wiki/Trojan_(celestial_body)) position. Using Earth and Moon as examples of our planet and moon, the second moon needs to be around one hundredth of the Moon's mass. It can be less dense, in order to be safely larger and therefore more visible in spite of its smaller radius. To the same purpose, we can posit it having a higher albedo. I think we can go with a S-type asteroid similar in size and density to [2 Pallas](https://en.wikipedia.org/wiki/2_Pallas). Cross section is one tenth of the Moon, but albedo can be 3+ times higher (i.e. brighter), so in the end we get about one third as much reflected light. Tides will actually be slightly less than Earth's. The second moon can barely get away with not having a perfectly spherical shape. One drawback of this configuration is that there will never be a conjunction - the two moons will always keep the same relative positions in the sky, about 60° from each other. [Answer] Have you see pictures or videos where Earth's Moon looks huge? I believe that the angular diameter of the Moon, about half a degree of arc, is the same as a dime held at arm's length, which is pretty small. But the Moon looks vast in many pictures and videos because telephoto lenses are used to film it. If you desire that both moons look like discs (when full) or partial discs (in other phases), both moons will have to be large enough to be (roughly) spherical. > > Solar System objects more massive than 10 to the 21st power kilograms (one yottagram [Yg]) are known or expected to be approximately spherical. Astronomical bodies relax into rounded shapes (ellipsoids), achieving hydrostatic equilibrium, when their own gravity is sufficient to overcome the structural strength of their material. It was believed that the cutoff for round objects is somewhere between 100 km and 200 km in radius if they have a large amount of ice in their makeup;[1](https://en.wikipedia.org/wiki/List_of_Solar_System_objects_by_size) however, later studies revealed that icy satellites as large as Iapetus (1,470 kilometers in diameter) are not in hydrostatic equilibrium at this time,[2](http://It%20was%20once%20expected%20that%20any%20icy%20body%20larger%20than%20approximately%20200%20km%20in%20radius%20was%20likely%20to%20be%20in%20hydrostatic%20equilibrium%20(HE).[7]%20However,%20Ceres%20(r%20=%20470%20km)%20is%20the%20smallest%20body%20for%20which%20detailed%20measurements%20are%20consistent%20with%20hydrostatic%20equilibrium,[8]%20whereas%20Iapetus%20(r%20=%20735%20km)%20is%20the%20largest%20icy%20body%20that%20has%20been%20found%20to%20not%20be%20in%20hydrostatic%20equilibrium.[9]%20Earth's%20moon%20(r%20=%201,737%20km)%20is%20also%20not%20in%20hydrostatic%20equilibrium,%20but%E2%80%94unlike%20icy%20Ceres%20and%20Iapetus%E2%80%94it%20is%20composed%20primarily%20of%20silicate%20rock,%20which%20has%20a%20much%20higher%20tensile%20strength%20than%20ice.) and a 2019 assessment suggests that many TNOs in the size range of 400-1000 kilometers may not even be fully solid bodies, much less gravitationally rounded.[3](https://en.wikipedia.org/wiki/List_of_Solar_System_objects_by_size#Larger_than_400_km) Objects that are ellipsoids due to their own gravity are here generally referred to as being "round", whether or not they are actually in equilibrium today, while objects that are clearly not ellipsoidal are referred to as being "irregular". > > > <https://en.wikipedia.org/wiki/List_of_Solar_System_objects_by_size>[1](https://en.wikipedia.org/wiki/List_of_Solar_System_objects_by_size) > > It was once expected that any icy body larger than approximately 200 km in radius was likely to be in hydrostatic equilibrium (HE).[4](https://en.wikipedia.org/wiki/Hill_sphere#Formula_and_examples) However, Ceres (r = 470 km) is the smallest body for which detailed measurements are consistent with hydrostatic equilibrium,[8](https://iopscience.iop.org/article/10.1088/2041-8205/776/2/L33) whereas Iapetus (r = 735 km) is the largest icy body that has been found to not be in hydrostatic equilibrium.[9] Earth's moon (r = 1,737 km) is also not in hydrostatic equilibrium, but—unlike icy Ceres and Iapetus—it is composed primarily of silicate rock, which has a much higher tensile strength than ice. > > > <https://en.wikipedia.org/wiki/List_of_Solar_System_objects_by_size#Larger_than_400_km>[3](https://en.wikipedia.org/wiki/List_of_Solar_System_objects_by_size#Larger_than_400_km) Vesta, which has a radius of 262.7 kilometers (166.3 miles), is the largest solar system object that looks irregular in a good photograph, although some of the ones larger than Vesta appear just as dots of light in the photograph. More or less arbitrarily assuming that a radius of 400 kilometers is necessary for a rocky body to appear round, one can calculate how close such a small moon would have to be to appear as a disc and not a dot of light, in the sky of your world. > > The maximum angular resolution of the human eye is 28 arc seconds or 0.47 arc minutes,[18] this gives an angular resolution of 0.008 degrees, and at a distance of 1 km corresponds to 136 mm. This is equal to 0.94 arc minutes per line pair (one white and one black line), or 0.016 degrees. For a pixel pair (one white and one black pixel) this gives a pixel density of 128 pixels per degree (PPD). > > > <https://en.wikipedia.org/wiki/Visual_acuity#Physiology>[5](https://en.wikipedia.org/wiki/Visual_acuity#Physiology) So an object with a radius of 400 kilometers and a diameter of 800 kilometers would appear to be a tiny disc instead of a point of light if it had an angular diameter of at least 0.008 degrees of arc. According to my rough calculations, that means that a minimum size round moon, with a radius or 400 kilometers (248.5 miles) and a diameter of 800 kilometers (497 miles), would have to be less than roughly 5,729,582.7 kilometers, or 3,560,197.6 miles, distant to be seen as a tiny disc and not as a mere point of light. The Roche limit of an an astronomical body is the distance at which it will cause a smaller astronomical body to break up. For Earth the Roche limit is 9,492 kilometers (5,898 miles). <https://en.wikipedia.org/wiki/Roche_limit#Selected_examples>[6](https://en.wikipedia.org/wiki/Roche_limit#Selected_examples) The Hill sphere of a planet, calculated from the masses of the planet and its star, and the distance between them, is the minimum distance that moon of the planet would have to be closer than in order stay in orbit around that planet. > > The Hill sphere is only an approximation, and other forces (such as radiation pressure or the Yarkovsky effect) can eventually perturb an object out of the sphere. This third object should also be of small enough mass that it introduces no additional complications through its own gravity. Detailed numerical calculations show that orbits at or just within the Hill sphere are not stable in the long term; it appears that stable satellite orbits exist only inside 1/2 to 1/3 of the Hill radius. The region of stability for retrograde orbits at a large distance from the primary is larger than the region for prograde orbits at a large distance from the primary. This was thought to explain the preponderance of retrograde moons around Jupiter; however, Saturn has a more even mix of retrograde/prograde moons so the reasons are more complicated.[3](https://en.wikipedia.org/wiki/List_of_Solar_System_objects_by_size#Larger_than_400_km) > > > <https://en.wikipedia.org/wiki/Hill_sphere#True_region_of_stability>[7](https://en.wikipedia.org/wiki/Hill_sphere#True_region_of_stability) > > In the Earth-Sun example, the Earth (5.97×1024 kg) orbits the Sun (1.99×1030 kg) at a distance of 149.6 million km, or one astronomical unit (AU). The Hill sphere for Earth thus extends out to about 1.5 million km (0.01 AU). The Moon's orbit, at a distance of 0.384 million km from Earth, is comfortably within the gravitational sphere of influence of Earth and it is therefore not at risk of being pulled into an independent orbit around the Sun. All stable satellites of the Earth (those within the Earth's Hill sphere) must have an orbital period shorter than seven months. > > > <https://en.wikipedia.org/wiki/Hill_sphere#Formula_and_examples>[4](https://en.wikipedia.org/wiki/Hill_sphere#Formula_and_examples) So Earth's Hill sphere extends to about 1,500,000 kilometers (932,056.7 miles), and its true region of stability extends to about 500,000 to 750,000 kilometers, (310,685.5 to 466,028.3 miles). The semi-major axis of the orbit of the Moon is 384,399 kilometers, or 238,854.4 miles. So this means that if a habitable planet has similar mass and distance from its star (a star that should have a mass similar to that of the Sun) any moons which it has which are large enough to be round will be close enough to the planet to always appear round (except or their phases), and never appear as mere dots in the sky. The minimum size of a rocky moon large enough to be round, with a radius or 400 kilometers (248.5 miles) and a diameter of 800 kilometers (497 miles), would be about 0.230229 of the diameter of the Moon, and thus about 0.0124228 of the volume of the Moon. If that moon had the same average density as the Moon, it would have about 0.0124228 of the mass of the Moon. The gravitational pull of astronomical bodies one each other are proportional to their masses and distances. So if a smallest possible round moon was at the distance of Earth's moon, it would have only 0.0124228 as much gravitational attraction on Earth as the Moon does. According to my rough calculations, if a moon with a mass of 0.0124228 that of the Moon was at a distance of 0.1114576 of the Moon's distance, it would have a gravitational attraction on Earth equal to that of the Moon. That distance would be about 42,844.189 kilometers, or about 26,623.144 miles. At that distance the minimum size round moon should appear to be roughly one arc degree wide, about twice the angular diameter of the Moon. Thus my rough calculations indicate that it should be possible for a moon smaller than Earth's moon to be close enough to an Earth like planet to appear as large or larger than the Moon does from Earth without raising any higher tides. Of course an astronomical situation which could possibly exist, is not the same thing as an astronomical situation which could form naturally, and an astronomical situation which could form naturally is not necessarily the same thing as an astronomical situation which could exist for the billions of years necessary until a planet developed an atmosphere with a lot of free oxygen and became habitable for beings with requirements similar to those of humans. The Moon is believed to have formed out of debris much closer to Earth than it is now, and to have raised large tides on ancient Earth, and gradually slowed down the rotation of Earth and moved farther and farther from Earth. The interactions between the two moons you desire, the planet, and its star could possibly eject one of the moons out of orbit around the planet long before the planet develops advanced multi celled life forms. One possibility you might want to consider is making your "planet" a giant habitable moon of a giant planet the size of Saturn or Jupiter. The larger "moon" in the sky could be the giant planet, and the smaller "moon" could be another moon of the giant planet. Rene Heller and jorge I. Zuluaga in "Magnetic Shielding of exomoons Beyond the Circumplanetary Edge" The Astrophysical Journal Letters, Volume 776, Issue 2, article id. L33, 6 pp. (2013) calculated the distances from a giant planet that a giant moon could potentially be habitable in. According to their calculations, the exomoon would have to be between 5 and 20 planetary radii to be shielded from radiation. <https://iopscience.iop.org/article/10.1088/2041-8205/776/2/L33>[8](https://iopscience.iop.org/article/10.1088/2041-8205/776/2/L33) At a distance of 5 to 20 planetary radii, the planet would appear to be about 5.7295 to 22.9183 degrees wide, about 11 to 45 times the angular diameter of the Moon. Any other moons of the giant planet that were large enough to be round would appear as discs and not dots whenever they were closer than roughly 5,729,582.7 kilometers, or 3,560,197.6 miles. Larger rounded moons would appear as discs at even larger distances. ]
[Question] [ This is my first post in this seemingly awesome forum. I need some suggestions for mobile communications in my detective novel. My story features a US police detective who is pitted against a group of billionaire funded mercenaries. In the first encounter, my protagonist and his detective partner follow a lead to a warehouse on the docks in the middle of the night. They are supported by a colleague with access to the full range of a major city precinct's police surveillance equipment. This surveillance cop becomes aware of some active communications in the area of the wharf but is not able to directly understand them due to them being encrypted. On entering the building a firebomb is triggered and not only is my hero badly injured but his partner is killed. I have a second bombing encounter, much later in the story, where my hero needs to be alerted to the presence and location of the mercenaries' communications a few moments before the bomb goes off, giving him time to escape the area. Aside from being able to identify the location of these communications, it's vital that my protagonist can be sure that the perpetrators are one and the same group, to enhance his motivation to avenge the death of his partner. I imagine, after the first encounter, that the surveillance cop puts in place a 24/7 monitoring system with an alarm set to go off when it encounters the same unique communications identified on the night of the wharf bombing. I wrote a rough draft revolving around military, channel-hopping radio technology but have been advised that this is a bit dated. The modern terrorist has better encryption opportunities by using mobile Internet data connections but I need someone to outline an approach that seems feasible and yet offers me my required plot devices. What forms of communication would fit these requirements: * They might be chosen by a current day, privately funded, quasi military mercenary group enacting terror on US soil. * They could remotely detonate a bomb. * They could be detected and their location identified by existing police surveillance equipment, even if they can't be decrypted. * They should have a unique identifier which could be recognised as belonging to the same group. To my mind, if the mercenaries are using burner phones, and fake online accounts, communicating over Skype or similar online chat, there would be no possibility of identifying them. This would suck for my story. I could of course opt for a signature explosive charge to identify the group but, if there's no advance warning of the second attack then my story will end abruptly if my hero dies. Cheers, Nigel Byron Bay [Answer] Detective workaround. I like "To my mind, if the mercenaries are using burner phones, and fake online accounts, communicating over Skype or similar online chat, there would be no possibility of identifying them. This would suck for my story.". Your detective feels this way. There is no way to bust into these communications that he can think of. He feels helpless, and dated. Maybe you do too by your comment about channel hopping. Have your detective propose that and his surveillance buddy smiles sadly. Write that into your story because you feel it and it will be good. But key: "This surveillance cop becomes aware of some active communications in the area of the wharf ". The bad guys are not in Kazakhstan; not all of them, anyway. At least one is local. Your detective has to be a detective - an old school detective. He might as well, because that is all he has got. Have him figure out where the local they heard was, physically during the explosion. He was nearby. Where did he go next? Figure out the guy and his movements. Plant a listening device, or arrange that the burner phones for sale in the bodega where he buys his smokes are all bugged. Or just tail the bastard and listen in on the conversation with his own hairy cop ear. I am not writing your story but I love to imagine the detective picking up the bomb right after the guy plants it and walking it over to the guys rental car and leaving it in the rear passenger footwell. [Answer] # Consider Metadata vs. Encryption vs. Content What makes communications unique? Once upon a time, with landlines and wiretaps, a cop or a counterintelligence agency would target a telephone extension, possibly by physically attaching a tap on the line, or by asking the phone company for itemized phone bills if there was no tap in place. The modern equivalent is to track a specific SIM card or IP address. And the modern countermeasure is to use "burner phones." But with enough computing power, it would be possible to look into each message and scan it. That's like listening to every phone call in a city -- clearly impossible when people sit at the switchboard, but computers can scale up better. Within their message, the bad guys are encrypting their content. That encryption could be a commercial or open-source, off-the-shelf system, but perhaps the bad guys are paranoid about those software packages being subverted by intelligence agencies. So they grabbed a few computer science textbooks, and a compiler, and wrote their own. That is their undoing. The self-made encryption program is not just vulnerable because of programming mistakes, it is also recognizable because of the non-standard data format. As a simple example, perhaps it is always two slashes followed by six digits followed by three slashes followed by 1024 lower-case letters followed by two slashes, repeated as many times as necessary for the length of the message. If the surveillance has the power to look into each and every message. With "power" I means not just computing capacity but also the legal permissions. The police usually doesn't have it. Intelligence agencies might have the right, or subvert safeguards to do it anyway. --- Follow-Up: 1. The cops get their hands on communication which they cannot read. Perhaps there was a file on a stick in a suspected hideout, or a dead letter drop, or perhaps an [IMSI-catcher](https://en.wikipedia.org/wiki/IMSI-catcher), or they are tapping one phone number of a possible contact. 2. They analyze the communication and see patterns. Perhaps there are three files attached which are called "something.jpg" but when they try to open the picture they find that there is no picture inside. But what they do notice is that all are exactly the same size, and all start with exactly the same bytes at the beginning, and exactly the same bytes at the end. They still cannot read the middle piece with the content, but the next time they encounter a file like this they know (or at least suspect) that it is the same bad guys. 3. Using some really serious pull at the DHS, they get the DHS to ask the NSA to monitor an entire city if more of these "corrupted jpgs" show up. That is probably illegal and unconstitutional in the US. So they still cannot read it but they can detect it. [Answer] If your protagonists can see who is transmitting to whom, but not the contents of the messages, then they can use [traffic analysis](https://en.wikipedia.org/wiki/Traffic_analysis) to deduce a lot of information about the internals of the terrorists' organistion. This includes their location(s), command-hierachy, and planning of future activity. Traffic-analysis is part of modern SIGINT (signals intelligence), and is used by most modern spy agencies. * Generally during the planning stage, traffic rates will step up. * The Command-hierachy, especially if its strictly command <-> subordinates, (even if several levels), gives very distinct traffic patterns. [Answer] 1. Military vs Commercial Frequencies. Communication use frequencies issued by government for that purpose, each radio station has permission to use that frequency, each phone company uses that frequency. (<https://en.wikipedia.org/wiki/Spectrum_management>) Most military frequencies are isolated for that purpose; and civilian communication tools don't use it. I imagine Russian communication system would be heavily encrypted by the only ones using those frequency (or stolen US military equipment). Its a pretty sloppy mistake, but its at least "detectable" as being transmitted, even if can't be read. However as you said, I would rather use data access that looks like nothing until it put through a Skype Chat (which has happened IRL). Its also much more contemporary. 2. My solution: Its not about their communication traffic you detect. Instead you detect them test the trigger for the explosives. They use a military remote trigger, not an insurgent style mobile phone. They are properly constructed so more reliable, and your mercenaries have used them before. As part of setting the explosives they test the remote control trigger (as part of setting the explosives, you would ensure it works, then connect the receiver to the detonator) it is detected as a unique military transmission. Bonus, the same signal was picked up during the last explosive too. ]
[Question] [ We may all have some familiarity with winged skulls - from Avenged Sevenfold's album covers to bikie shirts. However, for my science-fiction/horror story, I am curious about how these creatures would actually evolve and develop. Body Parts * These creatures would simply be skulls (around the size of a human skull - although it doesn't necessarily have to be a human skull) with wings attached to their back, and potentially a tail running perpendicular in-between the wings for balance and control during flight. They would have limited muscle and flesh, aside from tendons controlling the jaw, their wings, and tail (depending on what popular opinion says, I may close off the bottom of the skulls either with bone or flesh). Organs * All other organs would be internal, stored where the brain would be. As such, their brain will be smaller, and their lungs, stomach, and other organs would have to be quite small too. Habitat * Due to having no legs, and as such lacking an ability to land, these creatures would have to be perpetually in flight. As such, I am thinking of these skulls' habitat being around lava lakes and volcanoes, where the hot convection currents of gas could keep them afloat. Diet and Reproduction * I would definitely prefer these creatures to be carnivorous, and not be afraid to attack a human explorer through biting their flesh off them. Aside from that, they could also attack insects, birds and other animals on the ground. * Regarding reproduction, due to the difficulty in physical reproduction between these species, I believe releasing spores/sperm and eggs is the best way to go. A female could also release eggs, and a male could fly past and fertilize them. With all of these conditions in mind, *how could such a creature evolve?* [Answer] ## Although it sounds fantastical, the interesting thing is weirder animals have evolved than what you describe that exist or have existed. There is enormous variety in life. We have [starfish](https://en.wikipedia.org/wiki/Brittle_star), we have [octopuses](https://en.wikipedia.org/wiki/Cephalopod), we have Cambrian era [exoskeletal animals](https://en.wikipedia.org/wiki/Small_shelly_fauna). [Evolution](https://en.wikipedia.org/wiki/Evolution) is the gradual result of many, many layered mutations over a very long time. The important principle is that there is no goal in evolution - each gradual step is an optimisation/random mutation that makes evolutionary sense at that time. So for your flying skulls you need to consider that at every step of the way, each [evolutionary change](https://en.wikipedia.org/wiki/Natural_selection) must make sense and be an advantage at the time (or the place) it was made. Let's have a look at some possible scenarios to result in your flying skulls: 1. First, you need to start with an animal - the easiest is either a bird or bat. They already have the structure and beginnings of what you require. Bat wings use elongated fingers with stretched skin for flight, whereas birds use the entire arm for feathers. Your final fertilisation technique favours birds, as they already lay eggs. 2. There needs to be a scenario where bodies become less important, and the spinal column shrinks. This could be: * An increase in social requirements through [Sexual Selection](https://en.wikipedia.org/wiki/Sexual_selection). The brain requires an increase in size to obtain superiority in more complex mating procedures and defence against rival males / females. * The increase in brain size also comes with an increased weight penalty, and thus reducing mass of the body may be required to offset increased brain size * Stability is not too much of an issue now, as bird tails for flight have uses. Perhaps the environment changes to trees and short flight scenarios where lengthy flight is not required - this seems to correlate with increased social structure happening in smaller environments. 3. The spinal column, once shrinked needs to then disappear almost completely, and organs moved to inside the skull * Again, sexual selection is your friend here. Perhaps there is more protection by incorporating vital organs within your skull, so mates are chosen that appear to have this advantage. * Natural selection could also favour stronger 'exoskeletal' structures with organs located within skulls, with those that don't not surviving. Your flying skulls are thus evolved. It is important to note that residual structures would still exist - after all we have all evolved from fish so our embryos would form still like fish, just in later gestational periods the spinal column would be less and less important such that (like an appendix) it remains there in a redundant form at the back of the 'skull'. For look and appearance these are mainly Sexual Selection traits. Humanoid skulls with bilateral symmetry and humanoid features could be desirable from sexual attractiveness throughout. [Answer] I'd suggest starting with a bat, for three reasons: 1. Flying around constantly is very, very difficult. There are only a handful of animals that do it, and all are birds that are completely constructed for it, with enormous gliding wings and aerodynamic bodies. Skulls are not aerodynamic. However, bats already have tiny, easily-hidden legs, which can barely walk, but can be used to hang upside down from ceilings. This seems like a better option than continuous flight. 2. Most flying skulls in fantasy are pretty bat-like anyway, with flappy erratic flight and squeaky noises. 3. One of the most distinctive features of a skull are the large, empty eye sockets, and it's hard to create real eyes that look like empty eye sockets. However, bats already have large, empty sockets on their head - their ears. If you look at a human skull head-on and imagine its eyes as a bat's ears and the nose as the bat's dark face, it isn't hard to imagine that a slightly modified bat, flying towards you in the dark, could be mistaken for a flying human skull. You don't even need to remove the legs - the spindly legs of a bat could appear to be fangs extending down from the body, making it even more terrifying! Of course, even if you imagine the ears and face as the skull's eyes and nose, a bat still doesn't look that much like a skull, because a skull also has a big round head behind it. To explain this, let's say that this is a bat that has a large, inflatable "pouch" on the back of its head. Inflatable pouches aren't an uncommon feature in animals - it can be used as both a threat display or for mating purposes, or to create loud, deep calls. So this particular bat has a white back-pouch and a white body, with black ears and a black face. It is also more aggressive than most bats, and will dive-bomb intruders who venture near its cave, flaring out its pouch threateningly. With its ears and face silhouetted against its pouch and body, it could look very skull-like head-on and an unfortunate human who happens to wander into its cave could very easily report being attacked by a swarm of flying, screaming, fanged human skulls. [Answer] I think I would make this something that LOOKED like a skull, but wasn't really. More like a flying turtle with a spring-loaded jaw or fused lower legs (with claws evolving into 'teeth') capable of delivering a lethal bite/chomp. Let's say these operate in packs. Each bite may not kill an animal, but a dozen attacking a deer, say would lead to disabling wounds or lethal blood loss. Wings can be used like legs, so that is less an issue than it sounds like (some birds even had four wings). A groove on the body ('neck'?) to shelter wings would allow the skull to be kicked around some and not be killed or crippled. I agree a bat or bird would be the starting organism. The appearance may have evolved as a coincidence of function, or like the Japanese crabs resembling dead samurai, they were selected because of people's horror at eating something that looked like a human. They don't have to be good fliers. Nocturnal might allow them to sneak up on prey and just be way cooler. ]
[Question] [ In my fantasy world magic allows for low-level blunt-force, object density manipulation (Impact/collision manipulation, damage amplification). These magic spells require physical touch, and they can't be used on living things so no enhancing the human body for example. These two spells combined would allow the user to increase and amplify the damage taken by the target, or to put it another way it would allow the user to manipulate the force/overall intensity of impact making an object easier to break/destroy or a person easier to defeat (smash into a bloody pulp). From an outside observer it would appear as if the weapon user is endowed with super-strength, it would basically allow someone to simulate super-strength. The way I am picturing it, it would allow for soldiers to ditch metal based swords and other bladed weaponsfor cheaper magically enhanced blunt weapons made out of even the most rudimentary of wood for example. With the added excuse of metal being harder to manipulate through magic due to some intrinsic property, this would render metal weapons overly expensive, redundant, maybe even useless. People would eventually turn to wood to make weapons, due to being readily available and cheaper. I assume combat style would be less slicing and more smashing, allowing for a more blunt trauma type of warfare (Also suppose shields would become useless, as people would rather dodge than risk getting smashed to pieces, speed thus becoming an important variable). [Answer] No Well, at least not how you described the magic system. If the magic can only be used while touching the object, then there's a metal-based bladed weapon I can think of that's incredibly useful on the battlefield which isn't in contact with the wielder when touching the enemy. That is to say, arrows. Arrows, and artillery in general, is a fantastic force multiplier when used correctly, and thus metal-based weapons won't be completely ignored. I would agree with your assumption that metal personal weapons - i.e. swords, maces, lances, etc., the kind that you are holding onto when you use them on others - would definitely be replaced with wooden weapons. However, not necessarily battlehammers and clubs. Actually, I'd think the weapons would be replaced with gigantic longswords straight out of fantasy novels. If they weigh less and are stronger, you get bigger weapons. And while blunt trauma is tempting, remember that impact is just force / area, and thus not only will your blunt trauma be better, but your cutting edge on swords will be improved as well. Not to mention that swords can cut poles, so given that the combat will shift to giant weapons, everyone will be using sword-like weapons, because using a blunt hammer is asking to have a sword-user cut it in half. And then you're dead. And that is also why shields are going to be gone. I'd imagine that magic-boosted shields will provide a defense against the magic-boosted weapons, but when you can wield a sword the size of a door, who needs a shield? Not to mention that you can take a set of wood armor and apply magic to that. [Answer] Yes Congratulations. Guns are super easy in your world. You no longer need gunpowder to launch projectiles. Just have the hammer hit a metal ball with its mega increased force. The hammer on the gun is constantly in contact with the mage and the ball takes all the force and becomes a destructive force all its own. For that matter, ballista, catapults, etc. gain a lot of extra power as well. Just apply a force enchant to the launching mechanism and get rid of bulky counterweights. ]
[Question] [ In a world I want to make, sailors would travel at sea for many years, perhaps up to ten, on sail boats. Obviously, they'd normally be stricken by scurvy and such, but I was thinking of some kind of "super food" that could sustain them, even if just barely. I imagined a marine plant that could suck up plentiful water, but filter out the salt and other impurities. This plant would have all the things the sailors could not fish for, especially vitamin C to prevent scurvy. And, on top of that, the plant would have a good deal of water within, so that they'd continually have a source of fresh water. Is this possible in any way? Or is this a stupid "plot convenience" concept? Thanks. [Answer] What you're describing is not a stupid plot convenience at all and there is already some GM research attempting to make existing crop plants more salt tolerant by crossing them with plants like [mangrove trees](https://asknature.org/strategy/glands-remove-excess-salt/) and seaweed that have different strategies for either resisting salt intake through acidic roots, or methods to excrete it like mangrove trees to. This is becoming an increasingly important field of research due to soil salinity being on the increase in certain parts of the world. Crops that can grow in soils that contain more salt may well be the answer to this particular environmental issue. The problem is, to date there has been minimal progress on this in terms of breeding salt resistant plants that contain all the nutritional value that a normal food crop plant or tree may provide. It's not to say it can't be done, but just that we haven't done it to date. The bigger issue you face in this situation is that the tree that produces such nutritional food as you describe still needs to pull nutrients from its soil (or if grown hydroponically, from the flow of water over its roots). In other words, you can't just keep a bed of soil on a ship for 50 years and expect it to keep growing good crops. Crop rotation will help to some degree, but you will still need to replenish and refresh your garden soil from time to time. That said, your ship does actually have a source of fertiliser that can extend the life of the soil for an extended period; the sailors. Hiding behind the pleasant name of [Night Soil](https://en.wikipedia.org/wiki/Night_soil), human excrement has been used throughout history to fertilise crop lands and soils and actually makes sense as a source of nutrients that the plants can use to create new food. There is a catch however; human waste contains pathogens (diseases) that humans can readily pick up. In other words, you use the human waste from someone who is sick in your crops and everyone in the group is bound to get the same disease. Arguably you'd need some good antibiotics (preferably naturally occurring in the food), but in theory it's doable. Just not with plants we have today. In short though, there are already plants that grow and thrive in salt water including seaweed, which is itself a [good source of nutrition for humans](https://www.healthline.com/nutrition/benefits-of-seaweed), and mangrove trees which if their salt traits were bred into some form of orchard tree, particularly a citrus tree, could solve a lot of your problems. It could be watered with salt water, and then the fruit eaten in turn to provide nutrition to your sailors. Ideally, your orchard trees would use the same salt secretion method so the salt could be properly disposed of rather than a steady accumulation building up to toxic levels in the soil. [Answer] Mangroves grow in salt-water, so the salt-filtration concept works in the real world. Some mangroves [filter](https://www.amnh.org/explore/videos/biodiversity/mangroves-the-roots-of-the-sea/what-s-a-mangrove-and-how-does-it-work) salt from entering in their roots, some mangroves [excrete](https://asknature.org/strategy/glands-remove-excess-salt/) salt they've already accumulated, and some [store](https://www.amnh.org/explore/videos/biodiversity/mangroves-the-roots-of-the-sea/what-s-a-mangrove-and-how-does-it-work) fresh water internally. [Answer] > > Obviously, they'd normally be stricken by scurvy and such > > > They don't need to be so. Letting aside the requirement about fresh water content, certain (not so rare) [species of seaweed contain all the C vitamin a human needs](https://www.sciencedirect.com/science/article/pii/S2213453019300254) (see section 2.4) - even [vikings knew them](https://www.atlanticirishseaweed.com/seaweed-info/). A combination of seaweeds could cover all the vitamins. ]
[Question] [ [I've got my wizards, who operate by vanilla human biological laws and metabolism.](https://worldbuilding.stackexchange.com/questions/168496/the-eating-habits-of-metabolic-wizards) They've got an organ in the pelvis which has its own mechanism - not breaking the laws of physics - which stores energy in some form, and allows rapid dispension to use for their spells. What this means is that they have a biological battery, storing energy for the long term (weeks), which they can convert at will into some dynamic form. That can be combustion heat, electrical energy, or something else - which my organ (this is the only handwavy part) will turn into magical energy, and magic. Here's the numbers, and many of these have some wiggle room if necessary to make physical sense: * The organ weighs no more than four or five kilograms. Not big enough to displace too many existing organs, and not so dense to upset mobility. A wizard should not constantly feel pregnant. * The organ can store up to 200 megajoules of energy. * The energy can be released in as little as five seconds. * Ideally, the elements composing this energy battery should be able to be produced in the body - or at least composed of materials found in human nutrition. So organic fuels like petroleum are fine, but plutonium is out, because a human living in a pre-industrial era could never acquire any. * Ideally, the energy should be possible to be released in doses, but it is not required. * It's fine if the organ's energy medium takes weeks to produce, since that's how long it takes to metabolise fat and nutrition to charge it up anyway. Only the discharge needs to be fast. Now, what options are there for high-density energy storage that allows rapid discharge? Electrical energy was my first bet, but the densest real world batteries allow maybe a single megajoule per kilogram, which is two orders of magnitude below what I want to accomplish. Gasoline has this kind of energy density, but I do not know if you could combust it rapidly enough. Are there any other options? [Answer] # Fusion time, baby Oh boy, here comes the handwavium. For starters, the absolute easiest fuel present in the human body... is hydrogen! Because of what you've said in response to Trish, I'm going to go in the opposite direction and go as far from human biology as I feel I can manage. So we're going to make a magnetically suspended toroid (donut) of hydrogen plasma, and get it hot enough to undergo fusion. Hard to start, surprisingly easy to maintain. ## Materials A few things we're going to need right off the bat: hydrogen, carbon, iron, and copper. Hydrogen is actually produced constantly in the body by the krebs cycle in the form of free-floating protons that pass through a corkscrew like protein in the mitochondria to produce ATP. We're gonna borrow some, as we only need a few milligrams of the stuff. Considering that the human body uses [100-150mols](https://en.wikipedia.org/wiki/Adenosine_triphosphate) per day (if we stole that it would be 100-150g of hydrogen, orders of magnitude more than we need), we're going to have plenty. Next, we'll need some carbon. This will take some finagling, because what we really need is graphite which as I'm sure you can guess, is not produced naturally in any biological process I know of. However, [Hydroxyapatite](https://en.wikipedia.org/wiki/Hydroxyapatite), otherwise known as bone mineral, is precipitated naturally. So, this is not really so much of a stretch in all honesty. Iron. Our plasma toroid needs to be magnetically suspended so it can be nice and stable. Believe it or not, the biological precipitation of magnets actually has solid precedent in [Magnetotactic bacteria](https://en.wikipedia.org/wiki/Magnetotactic_bacteria). Copper, also found in the body although to a much lesser extent (your wizards better eat a lot of mushrooms), can be created in a similar fasion, even easier as it doesn't need to be magnetic. ## Design and Operation Our toroid of plasma will be magnetically suspended (using ferrous and electromagnets) in two layered toroids of graphite. The space between the two layers will be filled with liquid helium which will catch neutron radiation to produce heavier hydrogen atoms (deuterium and tritium) to fuel our fusion even more efficiently, and most importantly, help our graphite stay relatively cool. Assuming the fusion has already started up, we'll be using [Neutral beam injection](https://en.wikipedia.org/wiki/Neutral_Beam_Injection), which uses ionized hydrogen (H+) that the body so kindly provides through the krebs cycle, and shoots it into the plasma to stoke the flames of fusion. Our design is essentially going to be a scaled down version of the [ITER Tokomak](http://iter.org/factsfigures), which is where I'll be getting all of the following numbers. Making it about the size of a large donut, you'd have a comparable power output of 254 watts, using half a nanogram of hydrogen per second. Using Fusion power from a fraction of the body's atp production. This would produce your 200 megajoules in 218.7 hours, or a little over nine days. Ignition is going to require a pinch of handwavium, as with an efficiency ratio of 10, you'll need to provide 25.4 watts of input power to start and maintain the reaction. Considering that an elite cyclist can maintain a power output of [1000-1100 watts](https://en.wikipedia.org/wiki/Human_power), this is honestly pretty easily attainable. The application of that power can likely come in the form of an upscaled mitochondria, which already use electrical potential to produce ATP. This is biologically improbable, but it's nowhere near impossible. ## The Problem I always hate to say something's improbable, but to produce 200MJ of power instantaneously out of something that small, would not be containable using hard physics. The waste heat alone of just about anything using that amount of energy (like a fission reaction) would likely incinerate your wizard. This is where I'm hoping your magic comes in. The fusion power can easily provide tons of energy from biological sources, but I think the storage itself would have to be made almost entirely of handwavium. But hey, that's why you have magic! Perhaps the energy generated could be stored directly as 'magical potential'. ## Performance Regardless, here's an overview of your wizard's energy requirements and performance with this organ: * A little over nine days to produce the energy * 10% of that energy must be consumed as calories to maintain fusion, that equates to an extra 531 Kcals per day (How efficient!) * The storage method must be magical * Bonus points if someone hits the organ as it could cause a teensy tiny magnetic explosion followed by a plasma flash. Ouch! [Answer] The human body already knows three main variants of energy storage: sugars, protein and fat. # Fat Fat is long term, slow availability power that can be metabolized into sugar: 1 gramm of fat is 39 KJ, so for long term available 200 MJ, you'd have about 5.2 kg of fat stored under the skin. That would make you not that much more chubby by the way. It does not satisfy the 5-second demand though. # Glucose & Protein Glucose and other sugars are the high energy storage form of the body anyway. It is available from the liver by pouring out stress hormones and as a base level. Having a typical physiological availability of 17 kJ/g means that 200 MJ of glucose is equivalent to 11.8 kg of sugars - which is not feasible to be stored in one big organ. Proteins are the emergency energy, they contain about the same energy as glucose for the body. Burning that means that the body starts to cannibalize itself. # [Muscle-energy: ATP](https://en.wikipedia.org/wiki/ATP_hydrolysis) The body, however, does not simply use these substances, it uses the energy of the metabolized nutrients to turn adenosine-mono-phosphate into adenosine-di-phosphate and then into adenosine-tri-phosphate (ATP), which is the energy storage for muscles. ATP has a usable energy density of about somewhere between 0.08 MJ/kg[p7](https://books.google.de/books?id=1HBTDwAAQBAJ&lpg=PP1&ots=zuirdyx4mF&dq=Bray%2C%20Dennis.%20Cell%20Movements.%20New%20York%3A%20Garland%2C%201992%3A%206&lr&pg=PP1#v=onepage&q&f=false) to ADP and 0.128 MJ/kg to AMP. Which means to store all the 200 MJ in instant ATP would demand about 1.5 metric tons of ATP - totally not feasible. # Energy Storage organ The best energy storage would be in the shape of fat under the skin, followed by a blood sugar that surely would make you diabetic. Best it would be a mix of about 80% in fat shape, 20% as added sugars in the bloodstream or stored in several different organs. This would allow an estimation of the mage's reserves by looking at them: if they are chubby and well-fed, you know that the mage has a lot of reserves remaining, but if they are worn down and sleepy, they are not a threat. [Ponder Stibbons](https://wiki.lspace.org/mediawiki/Ponder_Stibbons) is not the dangerous one, but fat [Henry Porter](https://wiki.lspace.org/mediawiki/Dean) is! If the mages would need a special organ, it should be some kind of glucose-sack, right on top of the liver. Upon casting, an about liver-sized organ could release up to about 33 MJ (~2 kg) of energy almost instantly before it needs to refill itself. Estimating a higher metabolism rate or directed metabolism, such a refill could take the shape of some hours of meditation or a good night's sleep from the fat reserves. To get to the demanded 200 MJ of energy, a mage would need about 6 of these sugar bladders, each containing their 2 kg of glucose juice. Distributing them evenly over the body would be the most feasible method without disturbing the body shape too much. Chest, belly, and sides - where fat is stored anyway, would be the most logical positions. It also allows to partially neuter mages, by removing some of the organs. [Answer] Not possible on science-based. The best chance for storage stays with electrical power and frantic handwaving - something like [superconductive coils at body temperature and high saturation magnetic cores](https://en.wikipedia.org/wiki/Superconducting_magnetic_energy_storage) - just don't ask how such things naturally evolved into those wizards, it's magic But even so, there's a problem at the moment of using that 200MJ of energy in 5 secs (=4MW of power). At the moment of use, the superconductive coil is interrupted at some point and the current is diverted through some other circuit that causes the "magic". When switching, the voltage - otherwise null in a superconductor - will grow to provide an electromotive force. Looking to max voltages produced by the [electric eels](https://en.wikipedia.org/wiki/Electric_eel), some biological tissues could withstand 860V without breaking down - I'll assume then 860V of operating voltage to the magic-producing aparatus. Ok, so 4MW of power at 860V mean currents of 4650 amps, give or take. With even a 1e-3 Ohm resistance, the power dissipated by the conductors would be... - if your 800W toaster seem hot, imagine how a 21kW is (ohmic power losses to heat = $I^2\times R$) - over 5s, the amount is enough to boil 4kg+ of water. Now the problem: even if I'm assuming the diversion of this current to the magic circuit takes place through superconductive tissues (like the one in the storage coil), you know what happens when a single loop is connected to a source of immense currents? Exactly, rail-gun happens! Or anything that will try as hard as possible to keep the magnetic flux through that loop as it was - namely zero. And if the source of current is compelling enough to dissuade the loop away from keeping a null current, then the area of the loop will desperately be trying to increase as fast as possible - this is how the armature of a rail-gun gets accelerated to hypersonic speeds if and only if those rails are stubborn enough to stand their ground. Alas, the question doesn't allow the laws of physics to be broken, so I can't see what biological tissue can have the tensile strength to resist the circuit loop expansion forces; the only trick those vanilla-metabolism wizards could perform is to electro-mechanically explode first at hypersonic speeds, followed by a big ball of electrical arching and superheated plasma from the unconsumed portion of those 200MJ. If you want to see what I mean, look at this [backyard railgun - 26kJ](https://youtu.be/vAs9EHtKfVc?t=182) and watch carefully to those connecting cables on the sides of it. Then for the superheated plasma ball, [have this one](https://youtu.be/dsYJhqOIB9U?t=109) Big-EF Palpatine-thunderbolts-from-fingers, the reality is more exciting [Answer] The organ synthesizes and stores explosives, like TNT, in specialized cells. The organ can channel the energy released by exploding cells into mana, and also contain the gasses produced by the explosion. It vents into the digestive system slowly and safely, but the side effect is that wizards will pass an extraordinary amount of gas while this is going on. But this solution highlights a problem with your requirements. While protein has the elements needed to make TNT (and the nitrogen is already "fixed"), and while the stuff can quickly release the energy, the amount needed is excessive. To get 200 MJ, you will need about 50 kg of TNT. Nitro cellulose or nitrostarch might, biologically, be better choices. Possibly nitroglycogen. The body already produces glycogen, and sources of nitrates. All it has to do is to put them together, in large quantities. ]
[Question] [ We know that in biology, a species evolves to better survive its planet and its various climates and geography, which is mainly a result of natural selection. But, sometimes, this natural selection leads to consciousness, self awareness, and then intelligence. We know as a species, that life, or at least intelligent life has to exist somewhere in the VASTNESS of the universe, but there seems to be nothing. One theory suggests that all intelligent life has to cross a great filter, meaning species have to avoid certain natural events or action, such as the sun exploding or even climate change. But one thing that doesn’t seem to be on the theory board is evolving themselves into extinction. When I mean by “evolving themselves into extinction”, I mean that they either evolve to the point that their prey can’t compete, thus killing their main source of food, and causing a mass die off or extinction, or evolving to the point to were you cause more damage and harm to your own environment, thus killing your species But this leads me to my question COULD a intelligent species, or even a non intelligent species go extinct through some evolutionary path, or is this technically absurd? [Answer] Well, looks like the first case: > > they either evolve to the point that their prey can’t compete, thus killing their main source of food, and causing a mass die off or extinction > > > is very unlikely due to how evolution and mainly, the population development works. The simplest model of population growth shows that if the population gets too big, it shrinks simply due to lack of resources to thrive. If it has too much resources, it grows. After certain amount of time it should stabilise and never exceed its limit. The second case: > > evolving to the point to were you cause more damage and harm to your own environment, thus killing your species > > > is what might happen to us, so, I'd say: plausible. [Answer] Evolve to abiological organisms, then go extinct due to technological failure. This is a fairly well trodden trope - the advanced race uses technology, biological and otherwise which allows them use of better "bodies" to house their minds, but means the end of their lineage as a biological organism. The Asgard in Stargate are an example. > > The Asgard, pursuing means of extending their lifespans, began to use > cloning technology. The mental patterns of Asgard that became ill or > fatally injured were preserved by "downloading" them into computer > memory crystals. The patterns were later placed in a new cloned body. > This made the Asgard effectively immortal, but they lost their ability > to reproduce sexually... The > excessive use of the cloning process began to damage and degrade the > Asgard genome. This would result in the eventual extinction of the > race unless a cure could be found. > > > One might argue that the ability to clone new individuals means that the Asgard were not extinct as a race. Lots of organisms perpetuate themselves by cloning and evolution can still happen through chance mutation. It looks like the Asgard faced new existential threats as a result of this evolution to technological bodies. A species which sets aside conventional reproductive methods in favor of technologically advanced methods (robot bodies, cloning, etc) could be vulnerable to extinction from threats that could be weathered by a conventional biologic organism. These threats might be novel and not forseen by the individuals who decided to move their species in this direction. Or under the circumstances necessitating such a move, threats to the tech might be forseen but accepted as necessary. [Answer] ## It is completely possible. There are plenty of examples of this in science fiction. One example are the Asgard, from Stargate SG1. The quintessential grey aliens, they sought to become immortal. They eventually settled on a Heinleinian "transfer brain/consciousness between clones" system, allowing them to simply move into a new body every time their old one wore out. Over time, they started to experience problems with overpopulation. Since they ascribed to the Heinleinian School of Sci-Fi Thought, they decided that massive colonization was non-doable ("too expensive"), and thus instead decided to eliminate their ability to reproduce. Eventually, however, the excessive use of cloning degraded their genome, eventually killing them off. --- That being said, you may not want to go that route. As a result, here's a real-world solution to your question: ## Inevitable overspecialization. On a basic level, evolution is the process of exchanging the long-term benefits of genetic adaptability for the short-term benefits of specialization. A modern-day example of this is the Dodo bird. According to scientists, Dodo birds originally were a pretty standard bird, somewhat similar to a small flamingo (minus the pink coloration). Importantly, they were originally able to fly. However, they then became stuck on the small island of Mauritius. As their population grew, they were forced to take on features like larger beaks, stronger talons, and more powerful necks. These allowed them to get enough food to survive, at the cost of making them too heavy to fly. This worked really well for them in the (geologically speaking) short term; they flourished, and became the dominant lifeform on Mauritius. However, this overspecialization prevented them from adapting to no longer being an apex predator when the British arrived; they simply weren't able to adapt anymore. As a result, this overspecialization caused their demise. To summarize, the short-term specializations which natural selection selects for are limit adaptability. Over time the amount of specialization builds up, until eventually creatures like dinosaurs and Dodo birds completely lose their ability to adapt. As a result, any middling-sized changed to their habitat is enough to make them go extinct. [Answer] Yes. This happens all the time. Species have been known to completely screw themselves over and wipe out their prey source by accident. Organisms in general do not have any ability to restrain themselves and conserve prey so they do not wipe out their food source. Only sapient species can do that. They just eat whatever they can find or catch. If that means eating all the individuals of a particular species so be it, they don't care or have the mental awareness that in the long run they are dooming themselves to extinction by destroying their food source. A good example of this is when a predator is introduced into a new environment. The population booms in response to the new prey but then crashes once most of the prey has been eaten up. If the prey is too depleted the predator will go extinct before the prey populations rebound. This happens on s local level more frequently than a global one, but if it happens enough the species goes extinct. The only reason this isn't super common in nature is most prey species (both plants and animals) have defensive adaptations that make it harder for them to be easily eaten. [Answer] Of course. Human beings are doing it now, by burning lots of fossil fuels, which will in several centuries cause the planet to heat up to such an extent that humans (and most vertebrates) can no longer survive. See e.g. <https://en.wikipedia.org/wiki/Permian%E2%80%93Triassic_extinction_event> particularly the part (4.2) about the burning of massive coal beds. ]
[Question] [ So for this question there’s a Mad Scientist/Dark Lord that wants to engineer a race that can out breed mankind and carry him to victory. He has access to sufficiently advanced genetic engineering/plot contrivances to get the job done, but what anatomical features does he actually have to give to his genetically engineered humans to have them reproduce faster? Is it wider hips and narrower heads? Precociousness? A modified metabolism? Requirements: •They have to be intelligent enough to do basic tasks and take orders, intelligence may be significantly inferior to the average human but they still have to be capable of wielding weapons, harvesting crops and smashing rocks. •They must have a fertility rate that significantly outpaces that of humans, it can’t be an insignificant difference. •They can’t be absurdly smaller than normal humans. Note: If it’s too tricky to modify humans to be faster reproducers, what would some other genetic engineering options be? [Answer] Mass production of eggs would be the easiest, but staying as realistic as possible, I would provide the following: The biggest drawback of humans vs most other creatures is our growth rate. There are [unconfirmed theories](https://www.sciencemag.org/news/2014/08/why-do-humans-grow-so-slowly-blame-brain) that shows that while growing up, our brains consumes most of the energy our bodies receive, and leaves the body behind. Given this factor, if glucose can be administered biologically through the mother of children to assist in both growth rate of the brain and body we would be able to improve our overall growth rate. There is a rare condition called [macrosomia](https://www.mayoclinic.org/diseases-conditions/fetal-macrosomia/symptoms-causes/syc-20372579?page=0&citems=10). This is caused by genetic disorders such as obesity and diabetes. Macrosomia causes babies in the womb too grow at a faster rate and at normal pregnancy times are a lot larger than normal babies. If a mother can be genetically modified to boost this condition along with the high concentration of glucose, it could be possible to have babies born as early as 3 months at the normal size of a 9 month birth. [Twin births](https://www.medicalnewstoday.com/articles/324455) are caused when 2 eggs are present in the womb. Given the above factors as well as twin births it would result in a single mother should be capable of producing 6 babies in 9 months and possibly more if the eggs are increased in the womb to create triplets. At a steady increased growth rate, Children can possibly reach full adulthood at 5 to 6 years of age, a lot sooner if the rate is massive. There are however other factors to consider. One being overpopulation. Salmon produces hundreds of thousands eggs. If these fish had the lifetime of a human being, it would mean that the population would increase so fast that they would fill the oceans. Food would no longer be readily available and there would be a mass extinction. Instead, they have a life cycle of 3 to 8 years where after spawning, the parents would die. given the rate at which human population would reproduce, the life cycle should be dramatically reduced in order to ensure huge over population does not occur. We would expect a life cycle of a maximum of 20 years, perhaps even less. Food production would need to increase, this would mean that plant proteins would be the most common as it can be grown quicker than most meat producing animals. Last, but not least, gender factors of human babies born would need to have a steady ratio. If too little females are born, there would be a very high possibility of in breeding as there are not enough females to go around. If there is too many females, the growth rate of the army would be inefficient. Given the above ratios of human baby births as twins as well as the fact that all children would be able to produce more children at the age of roughly 6 years old. a single mother should be able to produce around 112 babies in her lifetime. a million mothers would be able to then produce around 112 Million babies in 14 years. There are rare cases of a mother producing [octuplets](https://en.wikipedia.org/wiki/Suleman_octuplets) which if developed instead of twins, could increase this number dramatically. [Answer] There are several options: 1) Larger brood size: Humans typically only give birth to a single child at a time. Simply ensuring twins most of the time will double reproduction. Larger broods will require breast-feeding in turns unless the women are equipped with more mammary glands. 2) Shorter gestation and interpregnancy periods: The time between pregnancies is a major factor. Human women are pregnant for 9 months, and becoming pregnant again less than 12 months after giving birth [is associated with birth complications](https://www.sciencealert.com/how-long-should-you-wait-between-pregnancies-here-s-the-science), making time between births at least 19 months. If this could be reduced to, say, 12 months, this alone will increase births by a third. 3) Younger age of fertility: How young women can be mothers is a huge factor. Human girls [as young as 6 years old](https://en.wikipedia.org/wiki/List_of_youngest_birth_mothers) have been known to give birth, but it is rare for women younger than their mid teens to become mothers. Halving the average age of fertility could halve generational length and produce far more offspring in the longer term. 4) Gender imbalance: If (say) three out of four children are females, half again as many people will be able to give birth. Gender imbalance can at most double the share of women, compared to normal humans, and if males make stronger warriors or workers, you would not want too great a female to male ratio. Let us assume that force-breeding normal humans would mean brood sizes of 1, 18 months between pregnancies, and 8 children (half of each gender) on average between age 15 and age 27 (average 21 years for a generation), then the female population will quadruple in 21 years on average, and with that, the birth potential. Let us now assume average brood size of 2, 9 months between pregnancies, and 12x2 children (18 female, 6 male) between ages 8 and 20 (average 14 years for a generation), the female population will increase 18-fold in 14 years and 76-fold in 21 years. That is quite a difference! [Answer] Simply said eggs. If we look at how many eggs most animals are able to put out it will dwarf the amount of live births(highest mammals do it around 30, while fish and insects can go in to the millions). And if you got full genetic control you could have the breeding mother be able to get pregnant straight after the first batch of eggs. After that it's a matter of making them hatch. A humanoid with eggs would have (initially) smaller offspring then regular humans (otherwise poor women if they have to put out several baby sized eggs). This means that these new egg people will need more time to grow to full maturity and seeing there will be a lot of them you will need a lot of babysitters. So this way your army will be larger faster but it will also take them slightly longer to get battle ready. [Answer] Option 1: The most important aspect of why human births take so long are not fertility, but length of pregnancy. If you make the cells of the unborn child multiply faster, your babies will grow much quicker and be able to be birthed. Add to that better given instincts, like that of newborn cows or foxes, and you'll sooner have "useful" babies that aren't entirely dependent on outside help for the first 2-4 years of their life. Option 2: If you want to make your dark lord even more dangerous and the world more disturbing, you can have his humans only be born as heads and maybe torsos, and then have body-parts that have been artificially created (or taken from corpses or live victims, etc.) operated onto these human frames. That also reduces the time needed for birth, as you save on unnecessary limbs. ]
[Question] [ So I'm working on a fictional planet which would experience a daytime sky similar to this. [![enter image description here](https://i.stack.imgur.com/8w24K.png)](https://i.stack.imgur.com/8w24K.png) This particular picture is from the movie Valerian: City of a Thousand Planets. Fictional alien atmospheres that are similar to this have appeared in various sci-fi media but I'm wondering if such a sky is actually possible? The fictional planet that I am working on should have a similar type of atmosphere. This planet is geographically similar to earth with the exception of its own unique flora and four (4) moons. It is also a human colony world of the far future. It seems to me that such a planet would need to have a thin atmosphere, effectively making it unsuitable to human life. Is there a workaround for this or should I simply resort to pure fantasy and ignore the science? [Answer] This could be explained by these cosmic object being sufficiently close to the planet so enough light reaches them to render them visible during daylight hours. Not unlike how the moon is also visible during day time hours. Multiple moons could explain the multiple visible planet like objects in the sky. It would however be unlikely two actual planets orbit close enough to be more than a pinprick in the sky. (Sidenote) If that's the daytime sky, the night time sky must be an absolute light show. If these objects are as bright, your planet's nights would be akin to twilight. They're huge and even a full moon here on earth is enough to lighten up a dark night a little bit. [Answer] The reason we don't see many "cosmological features" here on Earth is in large part because there aren't any near Earth. The solar system is essentially in the backwaters of the Milky Way; considering it "rural" wouldn't be wrong. Still, despite that, there are places in our solar system where more "cosmological features" are visible with the naked eye (to humans) for example, on any of the Jovian moons, the sky might be much more interesting: [![Surface view from Europa](https://i.stack.imgur.com/bhwiS.jpg)](https://i.stack.imgur.com/bhwiS.jpg) If Earth had rings, they'd be visible during the day, and if Earth were closer to the galactic core, the milky way would also be visible during the day: [![Milky way during day](https://i.stack.imgur.com/RNWFc.jpg)](https://i.stack.imgur.com/RNWFc.jpg) [Answer] Maybe consider the star supporting life on the planet as a relatively dim red dwarf or something. This would prevent the star's light from overwhelming the other light from the cosmos. ]
[Question] [ I have a planet where I want all plants to be blue and glowing. I was thinking that they could use something other than light for energy. I want the plants to always glow. The atmosphere is basically the same as Earth's. So is the soil. So I want to hear some of your ideas/suggestions. Main Point: What are some ways for plants on a planet with Earth's atmosphere and soil to glow blue all the time? [Answer] Scientists already have done something like this by mixing genes of plants with genes extracted from bio-luminescent bacteria. For example, [this research paper](https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0015461) and [this article](https://askabiologist.asu.edu/plosable/glow-plants) describe the creation of bioluminescent tobacco plants by injecting DNA from Photobacterium leiognathi into Nicotiana tabacum. It looks like the plants glowed green instead of blue, though [some research](https://www.ncbi.nlm.nih.gov/pubmed/16243898) has been done into getting those bacteria to glow red-orange instead. Arabidopsis cress plants were made bioluminescent by a [similar](https://www.theatlantic.com/science/archive/2017/04/whatever-happened-to-the-glowing-plant-kickstarter/523551/) [method](https://www.wired.com/story/inside-the-glowing-plant-startup-that-just-gave-up-its-quest/), although they did not glow strongly enough to be commercially viable. One way you can have it in your world is just by having that bacteria live inside all of your flora in a symbiotic relationship. [Answer] There are glowing fungi. Why not plants? [![glowing mushrooms](https://i.stack.imgur.com/cWwKy.jpg)](https://i.stack.imgur.com/cWwKy.jpg) <https://news.mongabay.com/2013/06/why-bioluminescent-fungi-glow-in-the-dark/> > > “Why do luminescent mushrooms, all of which emit light 24 hours per > day, which must be an energy consumptive process, glow at all?” > Desjardin asks. “There is no one answer to this question and we > suspect that different species may glow for different reasons, > especially dictated by which part of the mushroom or its mycelium > glows.” > > > Glowing fungi occur so glowing plants could too. These fungi glow all the time. It is a super interesting question why some fungi glow. It costs energy to glow and I have to think it would be one mutation to lose the glow and save the energy, so glowing must confer a fitness benefit. I like the idea that the glowing is a side effect of a molecule that offers protection against oxygen radicals produced by decomposing wood. That would explain why there are no glowing plants - they don't decompose wood. Your glow plants might be protecting themselves against some similar environmental hazard on your world. [Answer] It's easy to bioengineer a bioluminescent plant. The relevant chemistry doesn't change from plants to jellyfish, so just splice a few genes. They'll be dim enough that you'll barely notice the glow in direct sunlight, but it'll be enough to read by at night. If you want brighter, you'll run into metabolic issues. Would this ever evolve naturally? Hard to say. It didn't. And I'm having a hard time thinking why it would. Glowing flowers, maybe, to attract polinators, but that'd be seasonal. ]
[Question] [ Do you think it will become possible to create opposite sex clones in the future? A male clone from a woman or a female clone from a man? I think it will become possible. To create a female clone from a man you could take his cells and turn off the Androgen receptor genes. So the person will develop as female and will have Androgen Insensitivity Syndrome. A sterile woman with XY chromossomes. To create a male clone from a woman it would be needed to take her cells and add/create the [Sry](https://ghr.nlm.nih.gov/gene/SRY) system genes and put them into the XX chromossome. So there will be a male clone from a woman. [Answer] > > To create a female clone from a man... turn off the Androgen receptor genes. So the person will develop as female and will have Androgen Insensitivity Syndrome > > > This method would produce an individual that is genotypically male but phenotypically female, making them [intersex](https://en.wikipedia.org/wiki/Intersex). The resulting offspring would be a clone, but wouldn't be "genetically" female. Identity and psychology are an entirely different question, and many intersex people do identify with the phenotypes they express, but androgen suppression does not equate to a full genetic sex change. A more "accurate" alternative would be to duplicate the male X chromosome 23 - turning an XY into an XX. Though the resulting individual wouldn't be a perfect clone because the proportions of source DNA would be skewed, all the source material would come from the original male. Of course, you can't really do that without genetic consequences. For more information, research [creating offspring from same-sex parents](https://www.nationalgeographic.com/science/2018/10/news-gene-editing-crispr-mice-stem-cells/). > > To create a male clone from a woman... add/create the Sry system genes and put them into the XX chromossome > > > Add or create the Sry system genes from where? At what point does the new individual stop being a clone and become, more ambiguously, "genetically edited offspring" since foreign DNA is introduced? Why not just take an entire Y-chromosome from a related individual while you're at it? The bottom line is that no individual of the opposite sex can be genetically identical to its "parent" because sex is defined by different genes. [Answer] > > Female Clone from a Man > > > This is possible without doubling up on the X gene, seeing as how in human females, despite having XX genes, only one X gene is active in any given cell at a time. (This is responsible for the color phenomenon of calico cats.) It will take genetic manipulation though, as you'll have to turn the Y gene off. As it, completely unresponsive no matter what, and do this without upsetting the existing balance of the cell and inducing Turner syndrome. Honestly, the easier method is just swapping the Y for the same X. But this method will have the same DNA. Same library of DNA, anyway, because we've turned the Y into a Barr body. > > Male Clone from a Woman > > > Impossible in humans, I'm afraid. Even if you added the SRY gene on an X-chromosome, and you considered that to be an exception to the cloning rules, we run into a problem - Barr bodies. One of those X genes is going to be inactivated, so if it's the one with the SRY gene. And, like calico cats, it will be deactivated in some places, but exclusively activated in others places. This will no doubt lead to developmental problems. And placing SRY genes on both of the X genes won't help either, because then those genes will be treated as Y genes by the body, and subsequently the body will only register Y genes. This is also bad. [Answer] If your'e willing to loosen your definition of "clone" just a little bit, the same technique can be used in either direction. As noted in another answer, duplicating the X chromosome from a male, while deleting the Y, has potentially serious problems, in that the result will resemble inbreeding in terms of genetic duplication for any genes carried on the X. Further, there isn't a practical way to create a Y from an X to go the other way. So just adopt part of Mother Nature's method -- bring in donor chromosomes from an unrelated male (in the case of the male clone from female original) or female (vice versa). All other genes will be identical to the "parent's" genome, and by controlling which X is active (as noted in another answer, only single X is active in a female), the female clone from a male "parent" can be as identical as possible, while the male clone from the female "parent" will also be as identical as a male can be. There is another option (not necessarily a good one) for cloning a female from a male "parent" -- just delete the Y and leave things alone. This will give a female child with Turner's Syndrome, most of the effects of which can be countered with hormone supplements at appropriate development stages. Probably unethical, but possible... ]
[Question] [ Now that I created a lovable and sweet western dragon, it is high time to toss him into Hell. Obviously, slaying a dragon isn't an easy task, especially when he is actively running away from you. ## The stock dragon # Gyvaris is a mature, though still fairly inexperienced, impulsive and sometimes childish dragon. He stands about 190 cm at the withers and has a wingspan of 15 meters and a weight of 500 kg. His primary attack is his breath weapon: Using the power of his flight muscles, he can spray aqua regia (more precisely, its two components) up to 11 meters. The lethality of these acids usually comes from the nitrogen dioxide and the chlorine gas, created as HCl and HNO3 react and when aqua regia decomposes. Dragons usually have 3-6 liters of aqua regia (the sum of the volume of the two components) The dragon's scale resist aqua regia pretty well, while his saliva can partially neutralize and stall the acid, and is also a decent disinfectant. A dragon's bones can best be compared to high-end carbon fiber. Their scales also provide good protection. It can best be compared to a regular gambeson. The dragon's tail is at around half the total body-length, and it has enough power to break the sound barrier. It can be used for whipping, like [what water monitors](https://youtu.be/QQ3hrVarcb8?t=338) do. There's also the long, flexible neck (again, similar to water monitors) and the crocodile jaws (in terms of bite force). The dragon can also use his wing spurs ([think of the chaja](https://youtu.be/F7usYyVQ7I4?t=12)) and wing bones to bash the enemy. Other than that, the dragon has acute senses. Dragons are primarily gliders, using short bursts of powered flight to gain altitude. Dragons are omnivores, though they have a soft-spot for sweet fruits. Dragons have multiple lairs, with the primary one being in high elevation, and is usually hard-to-reach without flight. --- Gyvaris usually harasses people when they're in downtime, attacking their supplies, equipment and flying of into the distance while chuckling to himself. Gyvaris will first try to run, then try to attack with his breath weapon to make an opening for an escape. If that's not possible, then he'll concentrate fire on one person at a time (usually the archer(s)) and try to keep the others at bay. He usually first breathes acid, whips with his tail, occasionally attacks with the spurs, then bites. Clawing and kicking happen only when he's desperate. In hopeless situations, there's an 55% chance that he'll break down crying and beg for mercy. Dragonslayers is a well-funded group of people, who specialize in hunting down dragons like Gyvaris. The world's tech level is high medieval. How could they effectively hunt down and slay the specified dragon? It's an optional request, but I'd like if the dragonslayers were so overspecialized, that a simple act of domestic terrorism (something like the Red Wedding) could wipe the organization out. [Answer] There will be two somewhat different problems here - "how to hunt down" a dragon and "how to fight" against a dragon. Being intelligent, dragon would know to stay away from groups of armed people. Even if he can rout and destroy a number of human opponents, he's not immune to human weapons. Arrows would get stuck in his body, causing it to fester and lead to an undignified death. Dragon hunters would also try to avoid direct conflict. They would do their best to kill a dragon via ambush or indirect means, like poison. Hunting down the dragon would be not much more difficult than hunting a large bird of pray. Hunters would have to either use some kind of bait, or find dragon's lair. If there's a poison that is known to work reliably on a dragon, the hunt would go like that: hunters sneak into an area frequented by a dragon, attach a bag with poison to a sheep, let it graze in a meadow, and wait. A dragon would come for a meal, take the sheep and swallow the poison. Mission complete. If poisoning is not an option, hunters would wait with heavy crossbows. Unsuspecting dragon would be hit with several bolts before it can turn on attackers. If attackers can hide in the woods or some caves, dragon's attacks would be much less efficient. In the meantime, attackers will reload and fire again. Mission complete. Alternatively, hunters will find out where dragon is resting and sleeping. There they can either sneak and wait for dragon to return to complete their ambush, or sneak and find a sleeping dragon. Either way, mission complete. To mitigate the effect of acid, hunters can use wet rugs - very cheap and very efficient. Acid spray does not have much penetrating power. A rug can absorb a large quantity of acid before falling apart. At that point hunter would just discard the rug and pick up another one. [Answer] If the first response of the dragon is to just run, then the hunters either need to be able to kill/incapacitate the dragon very quickly, or have some way of immobilising it. Immobilising a large, strong, flying creature is not going to be easy; the hunters will need to be very well prepared. The first thing they will need is knowledge - not just of dragons in general, but of the specific dragon they're hunting. The first group of hunters will be scouts - specialists in camouflage, tracking, observation, and information-gathering from locals. The second specialisation of hunters will be a commander - someone with inference/deduction skills and knowledge of dragonkind who is smart enough to, based on the scouts' observations, be able to find patterns in the dragon's behaviour and the locations it visits and make a plan. If the scouts' information is incomplete, preliminary skirmishes might be required to test how the dragon reacts in combat. These skirmishers will be trained in the use of bows, lances and quick disengagement, mostly attacking in packs and scattering (so in the worst case, only one dies) at the first sign of aggression. They do not use highly effective weapons, and have several layers of woollen blankets, etc., that they can discard if covered in acid and are dull brown-and-grey coloured so they can attempt to hide if needed. The final attack will take place either at one of the dragon's lairs, if it can be found and is suitable, or at a tempting location - details will be specific to each dragon, but the scouts should have uncovered something. The strike force will include: * Net throwers, with weighted, barbed chain link nets. They will be inside the range of the dragon's spit, so this is one of the most dangerous positions, and multiple will be needed, because a single human can't lift or throw a net big enough to restrain a dragon like this. These hunters don't do anything else, they just train to throw big nets as far as they can, although they will participate in stabbing once the dragon is incapacitated. The barbs on the nets won't hurt the dragon but will get caught in the scales. Some large nets may be mounted on siege equipment, but that will have limited ability to target accurately and to conceal effectively from the dragon. * Tanks, who may be same as the skirmishers from test battles, since their equipment and skill set is similar - covered in dragon-resistant armour, padding, and blankets, and acting solely as decoys and to get net throwers out of danger. They will also have short staffs - metal poles about 5 feet tall and with spiky knobs on both ends. These are for holding upright if you're quick enough to realise the dragon is going to bite you - it bites the staff instead, which will hurt it but more importantly stop its jaws from closing on you. Tanks are also the ones who decide who to save; they're good at guessing the extend of wounds and viability of the wounded hunter, and know the more valuable hunters (e.g. lassoers) need to be saved first. * Heavy crossbow, who shoot from hiding, preferably from above. They will target legs, wings and shoulders first, trying to slow down the dragon and prevent it from escaping or killing (too many of) the hunters. The head will be too difficult a target at first, so focusing on the dragon's mobility and claw/wing attacks is the first priority. Not much they can do about the tail. * Ballista, hidden at first and uncovered once the dragon is in the right spot and at least partially immobilised. The dragon will obviously target it once it knows about it, so they usually only bother loading one bolt in it - it either works or it doesn't. * Lassoers. A complement to the net throwers, these focus less on reducing mobility and more on removing the dragon's methods of attack, especially the head and tail. They lasso a part of the dragon and then tie the rope to a pre-prepared stake; they are also able to use the stakes as a sort of pulley to pull whatever bit of the dragon they lassoed further down (friction prevents the dragon getting further away, and every time the dragon gets closer the slack is taken up again). The main job of the lassoers is to take out the head and tail; if they can lasso the head but can't pin it (because the dragon is still too mobile), they will attempt to at least draw the noose tight enough to restrict the dragon's neck and reduce its ability to spit. Particularly skilled lassoers can try to lasso two parts of the dragon to each other, which will very effectively reduce its movement and ability to fight. They're in range of the dragon's spit though, so they're vulnerable; they will hide behind a tank as much as they can. Most hunters won't wear much in the way of armour, since it's not much use - a dragon bite can be expected to crush even someone in plate armour. Basic leather protection would be useful against glancing blows, with padding (helmets are a must, too) since they can expect to be thrown around a lot. Mobility will be more important than armour. Face shields won't save a hunter from acid, but they might soften the impact - useless if you get caught in the middle of a stream of acid, but good to protect against smaller splashes. The opening shots will be from a siege net thrower, if available; after that the tanks will charge first, so the dragon is more likely to target them, shortly after which the others will do a coordinated attack while the tanks run around. If the dragon is able to be immobilised/dragged into the ballista's range, it will be used; if it can't be used or doesn't kill the dragon, once the heavy crossbows have weakened it enough and the dragon's primary attacks are not a threat, everyone can jump in with whatever stabby implement they have. If a dragon cannot be weakened or immobilised enough, the hunters will need to abort. Their survivability will be low against a dragon they've managed to piss off, but it will be better than staying in the fight without the resources to finish it. They will attempt to scatter so at least some will survive - those hidden (such as the heavy crossbows) will just stay hidden, the rest will just run and hope for the best, accepting that the dragon will catch and kill two or three. In some situations the hunters may be able to use more elaborate traps, such as oversized bear traps, large nooses, falling rocks/rubble, and pit traps. These require yet more specialised skills to create effectively and won't be able to be used in every fight (heavily location-dependent), so not all teams of hunters may have them. A very effective technique is to snare the head of a dragon (either with nooses/lassoes or with falling rocks) as it looks into a hole only big enough for its head, but it is too dependent on a good location and a stupid dragon to be something the hunters can use often. There will be a recovery and care plan for wounded hunters so they can get out of the fight and be patched up for the next one, considering how valuable their individual skills are. Hunters unable to fight anymore become trainers; particularly experienced ones may become commanders. Considering that even on a successful hunt the dragon hunters will usually have casualties, many of them fatal, they would not embark on hunts unless they have enough members in reserve to cover losses. They'd likely be organised into teams, with a team consisting of twice the members needed for a full hunt, plus their own commander and trainers. They'd have relatively stable memberships since a close rapport is needed to effectively carry out a hunt, and they wouldn't interact much with other teams other than occasional sharing of members and rivalries. They would occasionally recruit their own members, but would rely heavily on the organisation to fill gaps left by death and disfigurement. [Answer] ## Gunpowder You say the tech level of this world is "high medieval". The [High Medieval Period](https://en.wikipedia.org/wiki/High_Middle_Ages) is conventionally reckoned as lasting from 1000 to 1300. Knowledge of gunpowder first reached Europe towards the end of that period; it may have been used purely as an explosive at first, since there are no records of European firearms before the 1320s. [[1](https://en.wikipedia.org/wiki/Gunpowder_artillery_in_the_Middle_Ages#Use_in_Europe), [2](https://en.wikipedia.org/wiki/History_of_gunpowder#Europe)] So, your dragonhunters set some kind of bait to lure the dragon to a convenient location—let's say the bottom of a ravine—and then chuck a sufficiently large bomb down at it. The tricky parts are: not giving themselves away before the dragon gets into position, hauling the bomb up to the lip of the ravine in the first place, and knowing how long to make the fuse. (If the fuse is the wrong length, the bomb could blow up closer to the hunters than to the dragon.) Alternatively, and depending on how much prep time the dragonslayers have, the bomb may be in a cleverly concealed pit under the bait, with a very long fuse running through a tunnel. I'm thinking of [sappers](https://en.wikipedia.org/wiki/Sapping) here. ## Rocks If a big ol' bomb is not "medieval" enough for you, the ravine trap works pretty well if you just throw big rocks instead. ## Arrows While the heyday of the powerful [English longbow](https://en.wikipedia.org/wiki/English_longbow) wasn't until the 1300s, it did exist in the 1200s, so I'm including it. I'm not an expert and the Wikipedia page doesn't present a lot of clear conclusions, but if your dragon's scales are equivalent to gambeson armor, then it's plausible that English longbow arrows could penetrate them even at significant range (200 yards). Being closer might increase the force, of course. Even if the arrows don't penetrate the scales, the dragon's wings are vulnerable, and once it is unable to fly it will be easier to tackle. Here, again, the tricky part is getting the ambush set up in the first place. [Answer] Why has nobody suggested alkali? Pardon me for stating the obvious, but if you're dealing with acid that's the usual thing to neutralise it. Ok, they didn't have bleach in medieval times (and probably not Bicarb), but the Whitewash they used to whiten/clean their houses was usually alkaline being made from slaked lime (hence 'limewash'), which is largely Calcium Carbonate CaCO3. All it would take is an alchemist among your highly specialised dragon slayer force to (possibly accidentally) concentrate the limewash a bit, and voila you at least have a good plot device, some merry mayhem with the resulting chemical reactions (hopefully confuse the dragon a bit) and then you've opened the way to more conventional drayon-slaying methods as listed in the other answers. Just a suggestion. [Answer] George R. R. Martin covered this in his Game of Thrones series of books and bad TV show. But the idea he used is not his own. Basically, if you want to win some contest by force, you've got to out-muscle whomever you are going against. So your dragon is overpowered? Use something more overpowered. Like this, which can be conveniently hidden inside a large cart or wagon: ![Dragon-B-Gone](https://i.stack.imgur.com/ZJ8YL.jpg) You just need to hit it once, and then the dragon is no more. [Answer] The way to kill a dragon is with bows. something I propose a tube made of dragon bone or some other strong, but more carvable substance. One could attach a horse tendon or other strong and elastic string like thing to either side of the front of the tube as seen below. [![enter image description here](https://i.stack.imgur.com/goKvr.png)](https://i.stack.imgur.com/goKvr.png) after that one would push the loop of the string through the tube, and have it pulled back by either some mechanical device or some sort of draft animal or something. this could only be done in a settlement and not on the road, as it would require specialized set up. this means that once you fired you would not be able to fire again. once loaded it would look like this. [![enter image description here](https://i.stack.imgur.com/eIoxA.png)](https://i.stack.imgur.com/eIoxA.png) the bolt/arrow could be covered in some sort of poison which will kill the dragon. a large group could have one of these per person. In a fight with a dragon a large group of people could all fire their bow things simultaneously and at least one would hit the dragon, most certainly bypassing the dragon hide. The poison slathered upon the bolts would eventually kill the dragon. sorry for the odd illustrations, it was just the closest app I had. [Answer] While swooping down he is dazzled by reflected sunlight from Sir Knights mirror shield, crashes and is easy meat ]
[Question] [ Evil cyborgs, formerly humans, called the Overseers have set about building gargantuan megafactory arcologies that sprawl across the landscape. In order to keep the massive tangles of pipes and machinery that keep their strange pod-cradle exoskeletons alive & functioning, the Overseers require a workforce. They decide that humans who are pretty good at climbing around and have clever hands and brains would be a good choice. But there is a pesky issue to be dealt with: consciousness. The Overseers want to devise the most effective way to control the human workers, with minimal effort and maintenance on their part. Simple slavery will not work because the work is dangerous and the population to hard to control. Some sort of implant or biological engineering may be required. The solution to the Overseers' problem must. . . * Be relatively cheap, cost effective & easy to implement on a large scale * Leave the resulting workforce with sufficient dexterity and intelligence to do fairly complicated tasks like operate machinery * Leave the Overseers with the ability to direct & order the workforce around and in general assign tasks * Be within the limits of modern to near future technology & science; that is, no "magic nanotech" Essentially the Overseers want autonomous fix it and repair drones but lack the tech and resources to use actually robots. And they would prefer to use humans because humans are more clever and nimble and can fit into smaller spaces. However they want absolutely no chance of rebellion, so any solution in which the workforce is still human enough to rebel wont work. Basically "how to create/control a post human worker drone derived from a baseline human stock [Answer] Combine the following: HEAVY DEBT Introduce the humans to the shiny. Lots of shiny. Shiny costs big bucks, but we will let you pay it off. Envy The humans with the most shiny get things other humans don't. The humans get more shiny and go deeper into debt Rewards humans who do better fixes get more shiny. Divide and conquer Tell some humans they are not as good as other humans . Give some more shiney than other humans . They will fight each other and not you. The more different humans types you can make them think they are, more easy you control. Divide them up by as many things as you can. * Race * Religion * Nationality * Color * Creed * Urban * Rural * Etc The more division you can create, the easier it will be to control. Punish entire groups for the misdeeds of one. Get them to punish each other. Turn each group of slaves into masters of other groups. Sew distrust and hatred among them as much as possible, then be the arbiter of justice so that the only ones they trust is you. [Answer] Drugs. Not necessarily mind altering kinds, but highly addictive drugs. These could be tailored chemicals or what have you, but they should be tailored to do the following: Only release Dopamine while doing a sanctioned activity! Introduce these during early childhood. Dopamine triggering activities would include learning about their future job, going to and from sanctioned recreation, going to work, etc. Have the daily trip to the doctor include a massive dopamine hit, and then allow more of the drug delivered. In the case of bad activity, all dopamine gets blocked from the system. I'm no Psychiatrist but I remember reading that Dopamine is the precursor to all addictions. By controlling the where and when the brain can take up dopamine, you can literally make the populace addicted to working. The delivery system of the Dopamine drug could be a place to play with. Maybe you have two, one that allows a dopamine hit in response to certain triggers that only happen at work. A punishment could be a total dopamine blocker for a week, making the worker frantic to improve in order to get the hit. In addition, If you could also work on a hibernation angle, you could have Widget Twiddler first class B0B working. You have two more widget twiddlers on ice. B0B's performance falls off, or he starts behaving in un-sanctioned ways, they stop all dopamine, maybe introduce a poison and kill B0B. Then you thaw out B1B and he goes to work. You have no delay in services and the defective or worn out B0B is out of the way. ]
[Question] [ How realistic is the concept of a space gulag? So let's say you want another option outside of a stern talking too, a fine, confining to quarters, demeaning tasks, VR "re-education," beating the snot out of somebody, or showing them the door (i.e. spacing them). Maybe you need to keep them around for political reasons. Maybe they have a useful bit of knowledge that my come in handy some day. Maybe the crime falls in between beating the snot out of them and boiling their cerebral spinal fluid in an ocean of nothingness. How realistic is a space gulag in general? How realistic is it that they end up mining whatever it is on a brutal rock isolated from everyone else with JTK? What would the conditions be like? What would keep this place running? Mining output? Payment from the original society? [Answer] My answer is mostly based off recently reading Gerard K. O'Neill's The High Frontier, a book talking about the practicality of building self-sufficient space habitats. It was written back during the 1970's, but most of what it talks about holds up today. Long story short, O'Neill lays out a plausible scenario where humanity can build habitats cheaply enough and quickly enough to accommodate a population growing from not only new births, but also from immigration from Earth. These habitats would be rotating spheres, rings, or cylinders built from aluminum mined on the moon, large enough to sustain a population of hundreds at the smaller end of the scale, and tens of millions at the larger end. If you've reached the point where you can do this, then there's not much of a jump to make that you would start building habitats expressly to take the criminal population from other habitats. As for the habitats themselves, they can be made as brutal or comfortable as you like. In space, energy is cheap and plentiful, and atmospheric conditions can be maintained at whatever state you want. It would still be expensive to supply the prisoners with nice consumer goods, but there would be little reason to intentionally leave the ambient atmospheric conditions at anything other than pleasant, unless your intention is to punish the prisoners by making it too hot or too cold. If you plan on working the prisoners, I would actually suggest having them do something other than mining. A habitat is an enclosed environment that doesn't require any special equipment to live in, but a barren rock requires giving the prisoners access to life support, ships, heavy equipment, and then letting them out to work. You could make it secure, but it would be a lot of work. I would recommend having the prisoners work as farmers. Habitats are ideal for this purpose, as growing conditions can be kept optimal at all times, and the environment can be kept free of pests. It doesn't require much in the way of heavy equipment, though it would be more efficient if the prisoners had access to such gear; and the prisoners can supply their own rations, with the rest going to pay for the additional costs associated with a prison. [Answer] It's not very realistic to send a random person to mine. It currently costs [10000 dollars](https://www.nasa.gov/centers/marshall/news/background/facts/astp.html) to send a pound of mass to space. People want in time to reduce that to around 100 dollars a pound. But regardless, moving mass is very expensive. And you can't just move your prisoner, you need to move food, water, meds, toiletries. All this costs a lot. You're not gonna do that to some random prisoner. Mining requires complex and technical skills. You might do it to someone with existing technical skills. Suppose you have an existing mining industry, and someone is a spacer with certain skills that are useful for mining- computer programming, drill running, lubricant expert, astronomer, whatever. They do a crime, and they're offered an option of some horrible punishment (being sent back to earth, being spaced, being sold to slavers) or working on a mine, of their own free will. They work for x time and then their crime is paid off. They're motivated not to smash stuff up, and can bring useful skills to mining. [Answer] I follow a guy called Isaac Arthur and he actually had some very great and fascinating insights on the subject. If you want to do any really hard Sci fi he is an excellent reference. <https://m.youtube.com/watch?v=s_B_CJ3yieM> [Answer] Unless you actually start to cut back on safety and life support systems there is no reason to send a person which you can no trust on an expensive mission for something you can do by robots. If at all, then I would imagine a "we populate Mars and save fuel by one-way trips" scenario more likely. So which basically leaves this to uncritical missions which have a high likeliness of failing/death and things which can not be automated. It's important that you make it "opt-in" e.g. for people sentenced to death or lifelong prison, and that you then be someting like "you can evade death or lifelong prison if you go alone with a fleet of 100 small mining robots which you maintain to this asteroid and live there for 5 or 10 years alone, with nobody to help you in case of an emergency, radiation killing you with a chance of 50%, but then you are pardoned. (In this case the mining corporation would pay) ]
[Question] [ If you had elves who can train bulls and other animals to do all sorts of tasks... would bulls be useful as cavalry for war? Would they be useful enough to use a bull instead of a horse, in some circumstances? [Answer] * Suicidal chargers? Sure. A big strong animal is good. * Maneuverability is lacking I'd wager. * Speed. I think horses are faster. * Can a bull match a horses capacity to move for long periods of time? That is marching, maneuvering, scouting, charging...etc. And in war the ability to force march or keep fighting the longer is vital. More important that mere damage. And actual armies spent more time moving and camping than fighting. * Scouting. Does not seem like a particularly good idea to scout with bulls. * Riding. Would it be comfortable for a couple of hundred/thousands cavalry men to ride on bulls for hours on campaign? * Now what are cavalry? Scouting, harassing, chasing fleeing enemies, intimidation..etc units. And a horse does all those things well enough. * For charges speed and maneuverability is good. If you charger a line of pikemen and they don't budge you get the heck out of there and try another section of the army that is weaker. You don't just lodge your unit in the middle of the enemy. Also humans are making most of the killing and you armor the thing to begin with. * Perhaps there is a reason we stuck to horses or camels for cavalry rules. * Elephants are another matter. They had a different function altogether on the battlefield. [Answer] if you want it to just charge into enemy you can do it by burning their tail or other parts basically scare them to make them panic and stampeding the people in its front (may including yours) without riding it. but if you want to ride it as cavalry, it have horn that can get hook or tied by rope such as lasso by enemy which may can stop its momentum, it also not as fast as horse (unless in angry mode as far as i read from google, but i guess it not last long just a sudden burst) so maneuverability is poor against other cavalry type, but i believe genetic manipulation may can fix it, just my opinion. also that horn may can end up stuck with a lot of corpse weighting/dragging or slowing it down, and to remove it, he need to swing forcefully which is not that good for cavalry i guess....... unless the person can design special type of saddle to not get thrown out, but still that action (in attempt to remove the corpse) probably hampering/slowing it movement/momentum too, including disturbing the rider action in attempt to attack its opponent, and can endanger the rider from his own weapon. unless the rider is so skilled, strong, and fast enough to remove the stuck up corpse, after thinking again this may make the rider develop a tool for that specific reason, but i dont know what kind of tool it be. still i guess it basically to much chore compare to horse. so you probably need to cut/remove the horn to make it viable. [Answer] # Yes I'm going to say bulls could make good cavalry for war, as opposed to the answers given so far. In your setting you mention having elves who are proficient on training animals, I assume they would also be good at selectively breeding them to produce certain traits. All examples of bulls' characteristics we see nowadays aren't a result of optimization for war. Therefore it's very reasonable for your bulls to outperform out modern counterparts in a few desirable measures. Still, for my comparison to horses, I'll use the numbers available for current bulls, and records of past warhorses: ## Bulls: -Weight: 500-1100 Kg (heaviest recorded 1740 Kg) -Top speed: 35-40 km/h -Marching pace: 40 km/day (weightless) 15 km/day (comfortably) ## Warhorses: -Weight: 360-450 / 450-540 / 680-910 (Kg) (light/medium/heavy weight respectively) -Top speed: 20 km/h (for light cavalry charges) -Marching pace: 30 Km/day Bare in mind heavy warhorses were meant for carrying artillery and other supplies and it isn't confirmed they whether actually carried knights into battle in the middle ages. The horses that would be used for this would be the medium ones. Why is this relevant, because a horse can carry 20-30% of its weight on top of it. A suit of armor could weight between 20-25 Kg in the middle ages, with horse armor being an additional 23 Kg. An additional mention about marching pace, knights wouldn't ride their warhorses for everyday marches, they would reserve those for battle. # Advantages/Disadvantages Okay, so what do we have here. We have a stronger beast, capable of faster charges, while also being heavier so harder to stop and capable of more damage. Cavalry charges were partly used to cause soldiers to scatter and flee, a wall of bulls running towards you at 40 Km/h can be more effective at it that a wall of horses running at 20 Km/h. Also, bulls would carry more momentum, could be more heavily armored, thanks to their extra weight and could use their horns to deflect spears somewhat (especially if your elves are good at training them to do this, plus there can be horns attachments added to make this easier). Are they disadvantages? Sure, there's less endurance and maneuverability. Those are pretty relevant factors, I'll give you that. Some of this may be overcome with breeding though. Their deficit in maneuverability can be made up with tactics, perhaps your bulls can't retreat as fast. Okay, but maybe they don't need to, or not as quickly, since they are capable of more effective charges and could create more chaos on the enemies front lines. In addition, the heavier bulls could even carry two armored knights on top. Is this a viable strategy? I don't know. Maybe the one in the back is facing backwards, to defend the rearguard while the bull turns around. Maybe they unmounted when the charge looses momentum creating a stronger front, while the foot army catches up. Maybe elves are nimble enough and well coordinated to make this fighting style work. # Addressing the counterarguments As for the other issues raised. I don't see corpses getting stuck in the horns as such a big issue. I mean it's not clear to me goring would be all that common, much less goring and then the body remaining there. If this were an issue, the animal could be trained to try to remove the body tilting its head downwards. Worst case scenario you cover the horns so they are more bludgeoning than piercing weapons, a hit would still mess you up, but bodies would no longer get stuck there. As to bulls being worse at scouting and other cavalry jobs that focus on sustained speed and maneuverability, sure, I can agree to that. But those jobs weren't fulfilled by medium and heavy cavalry. That's the role the bulls play. I'd wager bulls wouldn't be great at archery or siege defense either, but that's not how you approach warfare viability. They don't need to be good a everything, just good at something that you can use. Another job the bull would be better at: counter cavalry shock tactics. Say you need to transport goods to your army (and this is of special importance to you cause bulls eat more). Your enemy has nimble cavalry that harasses your resource lines. Normal heavy cavalry isn't effective against them cause you lose on speed ot them. Pike-men could be useful but not if they shoot arrows at you and leave without engaging. So what you use to defend your caravans are more bull cavalry. Why? Cause same as the normal heavy cavalry, your knights will be more heavily armored so if they get into melee range is game over for the light cavalry, but the key difference is you bulls can actually catch up to them. Sure they can't keep up with a long chase, but if the attackers get into charge range, good luck. So this way, even if you don't have light cavalry (aside from scouting perhaps), you can still deny some of their advantages for your enemy. ### Sources * <https://as.com/masdeporte/2008/07/06/polideportivo/1215381892_850215.html> (40 km/h speed for bulls) * <https://en.wikipedia.org/wiki/Bull#Characteristics> (avg bull weight) * <https://en.wikipedia.org/wiki/Chianina> (heaviest bull weight) * <https://en.wikipedia.org/wiki/Cattle_drives_in_the_United_States> (bull marching pace) * <https://en.wikipedia.org/wiki/Horses_in_warfare> (horses' cahacteristics) * <https://history.stackexchange.com/questions/23892/what-are-the-capabilities-of-a-warhorse> (horses' characteristics) -https://www.metmuseum.org/toah/hd/aams/hd\_aams.htm (armor weight) * <https://www.amnh.org/exhibitions/horse/how-we-shaped-horses-how-horses-shaped-us/warfare/a-tank-on-legs> (horse armor weight) ### Edit: It was pointed out a horse top speed is actually 90 Km/h and not 20 Km/h as I initially claimed. That number was from wikipedia and corresponds to their maximum charging speeds, it's only this high since: "moving faster resulted in a break in formation and fatigued horses". That means that light cavarly could probably outrun the bulls chasing them, at least for certain distances. One of the sources claims bulls can maintain this speed for up to 400m, other sources spoke about horses doing faster sprints for only about 200m. So maybe the bulls still have a chance as anti light cavalry units, albeit with a shorter oportunity window. Additionally, bulls top speed wasn't measured for a mounted bull, or one wearing armor (for obvious reasons), so that's an obvious difference from the horses, that tips the numbers in favor of the bulls. Still, I take this liberty from the bull's lack of selective breeding for combat, and the fact that the weight differences means a rider and armor woulnd't be such a heavy toll for bulls, comparatively. [Answer] *YAKS:* Although yaks like high altitudes, limiting universal usage, it proves the concept that you can select and domesticate a related species for mounts and transports. People have yak fights, so they can be aggressive even after extensive domestication. The Chinese still use yaks for their military to patrol difficult terrain (<https://foxtrotalpha.jalopnik.com/why-china-s-army-still-rides-yaks-1837046487>) Suitably trained and selected for to be like yaks, cattle could be universal mounts, good patrol animals, excellent heavy cavalry (they'll never be as quick as horses) good beasts of burden, and (when all else fails) emergency rations. While yaks must graze, cattle can be fed grain, allowing for more sustained travel in field conditions. [Answer] You can train cattle as riding animals, you can train them to pull wagons, [you can train them for showjumping](https://www.youtube.com/watch?v=BNSEBhiR2s8). They're sluggish and not particularly agile. As with most animals, uncastrated males tend to be temperamental, with appropriate training they wouldn't be much more dangerous than an equivalent large stallion. The only real reason to use them would be that you couldn't get horses. Most of the answers given so far have addressed bulls as they currently are. * Bulls are they currently are are the result of thousands of years of breeding either for meat or just for breeding (dairy cattle). * Cavalry horses as they currently are are the result of thousands of years of breeding for riding and specifically in some cases, to be cavalry horses. To make them directly comparable you would have to consider adding at least a couple of centuries of specific breeding to be riding animals along with specific training to cope with the chaos of battle. Elephants have been mentioned, famously they were terrified of burning pigs and more of a danger to their own side once upset. Given the appropriate centuries of breeding, then yes, there's no reason why you couldn't use cattle in the place of horses for most purposes. However these bulls would look in profile a lot more like modern cavalry horses than modern bulls. Longer in the leg and leaner in the body, probably faster running with more stamina. They could maintain the horns, you'd probably have bred specifically for a horn that wasn't too wide or long so it was less vulnerable to damage or getting stuck. [Answer] ## Depends on the Bull Domestic horses have a maximum sprinting speed just over twice that of domestic cattle (~55 mph vs ~25mph according to Google) This much lower top speed makes them a poor choice in any of the roles warhorses typically filled. In fact, they are more mobile than domestic cattle in every single way which is why cowboys use them so effectively for herding. That said, there is a kind of bull that can more or less match paces with a horse and that is the [Blue Wildebeest](https://en.wikipedia.org/wiki/Blue_wildebeest). They have a top speed of ~50mph which means that they are only marginally slower than horses, but fast enough that you generally would not want to push either animal to its full speed unless you are very experienced and have a very well designed saddle and stirrups; so, in practice, this slight max-speed difference won't really come into play. Since your question is about elves specifically, the wildebeest may be a better mount than horses specifically if your elves are a bit smaller than humans. A wildebeest is a bit too small for humans since they are only about 1/2 the mass of a horse; so, whereas a 120kg armored knight is about optimal for a 550kg horse, a 60kg armored elf would work just fine from a 275kg wildebeest. Appart from being more "to scale" for them, the wildebeest could give the elves all sorts of tactical advantages like: * They are shorter; so, they could hiding cavalry behind grasses and shrub lines that would be too low to hide horses in. * They have two toes; so, they can can maintain thier balance on uneven terrain better than horses allowing them to maneuver and charge over terrain that would stop a horse. * They are smaller; so, keeping them feed is easier meaning you could breed more of them with the same effort. * They are more maneuverable which would make them better at all sorts of cavalry things like chasing down zig-zaging routing infantry, skirmishing, and avoiding spike pits or other anti-cavalry traps. [Answer] > > If you had elves who can train bulls and other animals to do all sorts of tasks... would bulls be useful as cavalry for war? > > > When compared to horses, bulls are: * Harder to control in harsh situations * Less agile * Easier to scare * More likely to trip on an obstacle They also have a gait that makes it very uncomfortable to mount them (believe me, I tried). So, if all you have is bulls, maybe go for it. Otherwise use horses. > > Would they be useful enough to use a bull instead of a horse, in some circumstances? > > > People here in Brazil mount bulls and cows all the time because sometimes that's all you have (I don't know, but I think horses are more expensive nowadays. I'm sure they were so 30 years ago when I used to ride them). [![People riding cattle](https://i.stack.imgur.com/X4SUn.jpg)](https://i.stack.imgur.com/X4SUn.jpg) If you are still obsessed with cattle usage in war, it can work as long as the opposing side does not have gunpowder. You might like to read about the [battle of Tondibi](https://en.wikipedia.org/wiki/Battle_of_Tondibi): > > The Songhai battle strategy was poorly thought out, as the plan to send a stampede of 1,000 cattle to break down the Moroccan lines and to cover their infantry (who lacked the technology of gunpowder weapons) failed, with the cattle charge being repelled by the noise of gunfire and the sound of cannons, which caused the cattle to stampede back towards Songhai lines. > > > Seems like this kind of strategy used to work in ancient times though. ]
[Question] [ In other words, What physical law can X manipulate in order to control the weak force? And as for the abilities, I...don't have the greatest grasp of what someone can do with the weak force as their lay thing. Out side of causing fission and fusion reactions/explosions and irradiating everything. So some pointers on what else can be done with the weak force. An extension of two other posts:[What would powers based on electromagnetism look like?](https://worldbuilding.stackexchange.com/questions/162402/what-would-powers-based-on-electromagnetism-look-like) and [What would powers based of Gravity look like?](https://worldbuilding.stackexchange.com/questions/161608/what-would-powers-based-of-gravity-look-like?noredirect=1&lq=1) [Answer] The most interesting possibility here is nuclear alchemy. If the practitioner can have very fine grained control over the weak force on bulk materials, the possibility exists that they could trigger specific modes of radioactive decay in specific elements, causing them to become other, possibly more useful, (and perhaps even stable) elements. "Impossible" materials which would be too short lived in real life could be made stable, at least whilst under control of the practitioner. This also means that you could, in fact, transmute lead to gold, assuming you were adequately protected against the interesting varities of radiation that the intermediate states would produce. You wouldn't be able to create heavier elements this way... no transmuting lead into uranium, as gluing extra nucleons on needs the strong force (but if you have a wizard who can control that, maybe you could work together). Only transformations that conserve or reduce [mass number](https://en.wikipedia.org/wiki/Mass_number) would be allowed. Note also that the weak force allows for the transmutation of a proton or neutron into its own antiparticle. This isn't elemental or isotopic transmutation, and as the resulting and inevitable annihilation with any nearby nucleons is not mediated by the weak force you'll get a load of quite unpleasant radiation in pretty short order. If you're not mkaing antihydrogen for CERN, this might only be useful as a sort of suicide bomb. The practitioner would not be immune to the effects of radiation, as most damaging radioactive effects are mediated by electromagnetic interaction of ions or short-wavelength photons with matter. They may on the other hand be able to suppress radioactive decay in their body or immediate surroundings, making them much more resistant to the effects of radioactive fallout and you certainly wouldn't be able to pull a [Litvinenko](https://en.wikipedia.org/wiki/Alexander_Litvinenko) on them. They'd be able to benefit from cheap land prices around Fukushima, though they might not have many guests. Given that depleted uranium is seen as something of a waste product of a nuclear-armed power's enrichment programs, turning this hazardous waste into valuable material might even be seen as something of a public service, and has the added benefit that uranium is so heavy that you could create almost any other useful material from it. Similarly, denaturing radioactive waste into shorter lived isotopes or even stable ones would be very valuable indeed. Depending on how you want your powers to work, people with this ability might have some kind of material sense... you can't work out a nice decay path if you don't already know what collections of protons and neutrons you're dealing with, after all. How that turns into a useful power is up to you, but you can be sure that an alchemist knows their lead from their gold, and you'll not be able to sneak debased currency past them. Killing people or damaging things by making them intensely and briefly radioactive or spontaneously fission seems a little crude in comparison. Power-balancing this seems likely to be awkward, though restricting the range of the effect might be thematically appropriate. Don't accept massages from people wearing lead aprons and gauntlets, in case it wasn't already suspicious enough! Restricting the effects to elementally or isotopically pure materials might also work, so you might transmute a lead pipe but not a person. The biggest problem is of course what to call them. "Weakling" would be an obvious epithet, especially from people capable to chucking lightning bolts or levitating, but probably best used only by those who are bored with the lack of cancer in their life. [Answer] I find it somewhat helpful to think of the Weak Force analogously to the Electromagnetic Force (there's a reason they were the easiest to unify, after all). Neutron decay can be modeled as a free neutron emiting a W- boson, which immediately turns into an electron / antineutrino pair. Compare to a charged particle emitting a photon, which, given high enough energy, could turn into an electron / positron pair. So, just as it's necessary to ask what aspect of the force one manipulates and in what way for Gravity and EM, we must consider what specifically we're doing with the Weak Force, even if we ignore the more exotic things like extending the lifetime of Muons to start cold Fusion in the oceans and blow up the Earth (bwahahaha?). Messing with W or Z bosons directly would be analogous to messing with light, and I'm not sure what you'd be able to do with that (what is the mechanism for a carrier boson becoming leptons? I just plain don't know, and all that comes to mind is "something something Higgs Field", which is way beyond the scope of this question). So maybe you're controling when and how which particles emit Ws? In which case, you can make, say, 1/6 of the electrons in a piece of diamond give up their Weak charge, aiming the W- at the carbon nuclei to which they're bound. The electron becomes a neutrino, and if the W- hits a proton, it becomes a neutron. Congratulations: you just turned Carbon12 into Boron12. Or maybe you want a piece of Lead to spew the Weak charge from its neutrons until it becomes a piece of Gold. Both examples mess with the chemistry, though. What would happen if all the Carbon12 in a diamond suddenly became Boron12? You just lost an electron, and the proton mandating its orbit. Is the diamond going to crumble? Most of the time something like this happens, it's in a plasma that just doesn't care, or in a neutron star, which also doesn't care. What if you're not converting a solid to a solid,? What if you're converting Carbon to Nitrogen? Either your diamond immediately sublimates, or you just found a very weird way to freeze things (now, explain where the temperature went, because Thermodynamics isn't giving up that easily). Either way, the easiest way to kill someone with this power is to transmute the atoms in their body. One way or another, that's unhealthy. If you want to be flashier, bake a bucket of heavy water under a shower of long-lived muons. You might not have an easy time Weak-bending your way through steel, but wood, plastic, or any other solid that relies on light elements could probably be damaged quickly (what happens if you turn bound hydrogen atoms into neutrons?). And if you can vaporize diamonds by turning them to nitrogen, or turn NaCl to NeCl (or is it ArCl I always get Neon and Argon mixed up), that could be fun, too. You know, until you turn a bucket of salt into a bucket of neon and chlorine, which might be a war crime if abused. ]
[Question] [ I am writing a detective story where one of the detectives can read people's minds; however, as this cannot be used in court they need a machine that can a) record and visualize an individual's thoughts, and b) differentiate between mundane thoughts and thoughts that an individual will actually do. However my conundrum is that if a machine could do these things, then what would be the point of the Telepath in the first place? My idea was that the Telepath can read thoughts and memories and is able to 'pull' these memories to the surface or conscious, but the machine can only read thoughts; what an individual is currently thinking, but cannot read memories. So, a non-telepath wouldn't be able to use this machine as they would have no idea how to navigate an individual's mind. Do you think this makes sense or not? Any ideas are welcome. [Answer] A telepath is a craftsman. Diffrence is like with custom made suit made by tailor and store bought one. Machine record is crude, thought and feelings and "visuals" lack crispiness. Sometimes the are contained with other thoughts "I will kill Jon Doe tomorrow, Tomorrow Bet your bottom dollar That tomorrow There'll be sun!" . Machine need a validator. So in a room full of people there need to be someone who would validate that it was John Smith thought and not someone else. (If you're plannign to commit a crime think in other language than your native one). Machine is a machine, you might become "aware" of it's working by having your thoughts suddenly dissapear "lost track of my thought". Or you don't want to think about something yet something is pushing you to do that. A telepath (and skilled one) can easily go into discourse with you pretending to be your selfconciousness. They can wait for the thought to appear and then encourage you to unravel them "I thought about killing Joe Doe. First time I had that thought was when I saw him murdering all those kids in back alley. Then he throw me into asylum and used my family money to become the mayor". So a machine would be fine to find if any of the passengers is constantly thinking about that bomb he have in his pocket. A telepath would know who give it to them, what they looked like, where t was, do they know how to defuse it and so on. [Answer] The distinction between living telepaths and memory viewing machines is comparable to having a conversation vs reading a script. The machine queries the subject's mind and receives a response. The telepath interacts dynamically with the subjects mind, choosing each new query based on subtle aspects of the previous response. A telepath can bring nuance and intuition into the process where a machine can only follow its script. In theory, a skilled operator could mimick a good telepath, choosing each next scripted question only after viewing the previous reply, but the process would be much slower and the subject would have much more time to plan their replies because of the time needed to view the previous reply and then enter the next question. [Answer] Detectives' gut instinc leads the investigation. Your police officer knows sweet granny Elizabet poisoned her grandkid and now he searches for proof. Knowing your suspect IS the bad guy lets you focus your attention on it instead of chasing 40 probable suspects. Only 1 house to search instead of 40. Only 1 search warrant is really likely to be approved. This is a boon any detective would give an eye for! [Answer] ## The Machine is Large and Expensive Basically, the machine is like a supercomputer. Their size makes them completely stationary and as they are expensive to build, time on them is at a premium and needs to be applied for. There may also be a significant backlog on getting time on the machine, and there's certainly a lot of paperwork involved. So from a department's perspective the telepath is a cheaper, portable version of the machine they can deploy at will. [Answer] ## Organic Memories aren't accurate representations of the facts Latest research into how memories work shows that when someone remembers something, their brain is re-experiencing it and taking notice of what they choose to at that present and their brain's current context. This has huge ramifications for memory because it means that memories aren't entirely infallible, and due to the fact the memory is being re-experienced, something minute is changed every time. You see this all the time with acceptance of trauma and coping with difficult memories, or trying to rectify the memory of something someone particularly feels bad about. They'll often unconsciously make minute changes to other parties' intentions or even situations, maybe add more context, in order to frame themselves more sympathetically (the human brain is hard-wired for optimism, to cause itself less pain). This is how people eventually over time learn to accept traumatic events in the past, and is a pattern often seen in murderers trying to live with their actions. If a memory machine can capture a memory in one form, it is less susceptible to how the rememberer's current brain state can bias the memory. However, if you have an older machine-based recording of the memory, and take a current sample, you can notice biases that a person is unconsciously adding to their memories. [Answer] ### Because it gives you information For example, you may have a murder investigation. Reading the murderer's mind can lead you to the exact patch in the forest where he buried the body, so you can exhume it and search for clues, where any other detective doesn't have access to those clues. You can read the minds of the drug couriers, you'll never have to pull someone out of the airport line that isn't guilty, but you'll catch all the real couriers. And you'll know exactly where they have the drugs, so you can prove it easily. (I am aware that there are methods to smuggle drugs that use unaware couriers - but there's still plenty of aware couriers that this would have incredible value.) TL;DR: Just reading the actual criminal's thoughts can help you find evidence. ]
[Question] [ Unless I am mistaken, a [Jaculus](https://en.wikipedia.org/wiki/Jaculus), also called a javelin snake, is a creature found in Roman myth, described as a snake that hurls itself from trees and impales its prey. Its head is usually described as being somewhat pyramidal and is the part being used for impaling. They impale their prey with their heads. So I was wondering, is there any way this could exist in the wild? And if so, how large would it be and how would it evolve? Thanks! [Answer] # This is quite possible First of all, there is a type of snake that can glide from the trees in order to catch its prey. It is also called the [flying or gliding snake](https://en.wikipedia.org/wiki/Chrysopelea). Wikipedia states: > > Once it decides on a destination, it propels itself by thrusting its body up and away from the tree, sucking in its abdomen and flaring out its ribs to turn its body into a "pseudo concave wing", all the while making a continual serpentine motion of lateral undulation parallel to the ground to stabilize its direction in midair in order to land safely. > > > --- Second of all, reptiles with horns already exist in nature, such as the [rhino-horned lizard](https://en.wikipedia.org/wiki/Rhino-horned_lizard), and there's even an actual [horned snake](https://en.wikipedia.org/wiki/Cerastes_cerastes): [![enter image description here](https://i.stack.imgur.com/U15lTm.jpg)](https://i.stack.imgur.com/U15lTm.jpg) [![enter image description here](https://i.stack.imgur.com/PQW69m.jpg)](https://i.stack.imgur.com/PQW69m.jpg) --- Finally, of course there are plenty of animals that exist today that use their horns as weapons, to name some: * [Rhino](https://en.wikipedia.org/wiki/Rhinoceros) * [Deer](https://en.wikipedia.org/wiki/Deer) * [Moose](https://en.wikipedia.org/wiki/Moose) * [Narwhal](https://en.wikipedia.org/wiki/Narwhal) --- So, putting all of these facts together, it certainly seems possible for there to exist a type of gliding snake with a thin horn or tooth (a Narwhal's 'horn' is actually a tooth) used to skewer its prey. This becomes especially possible in the depictions of a [Jaculus](https://en.wikipedia.org/wiki/Jaculus) that have wings and sometimes even legs. --- ### What it would look like in real life A Jaculus in real life would likely have the following features: * Hind legs for jumping off of trees * The ability to "flatten" its body parts, allowing it to glide efficiently * A thin, slightly curved horn which it likely sheds often with its skin It would climb up trees, scanning for prey. Upon locating its prey, it would jump off with its hind legs, flattening its body while it glides. Once it is close to its prey, it would unflatten its body but keep its legs flattened, which causes it to point downwards from the drag. Finally, it unflattens its legs and falls onto its prey horn first, stabbing its prey. Sometimes the Jaculus might miss, which is fine because at that point it will quickly swing its horn and whack the prey, stunning it long enough to bite it. EDIT: Even without the gliding ability, its legs would likely allow it to jump forcefully enough to skewer its prey, especially if it jumps from varying heights and uses gravity to its advantage! [Answer] Gliding snakes are, as the other answerer said, a thing - in fact, Chrysopelea snakes can actually glide further than any other animal, at around 200 metres. However, as you commented, the glide is very slow. I think the only strategy which would produce enough force is simply launching its body a shorter distance, and skipping the gliding part - essentially, jumping. There are snakes which can jump quite impressively, namely the painted bronzeback: [here's one in action.](https://youtu.be/t-N02N-PKXQ?t=13) I think this is your best bet for "hurling itself from trees". The pyramidal head is also fine, as members of the viper family tend to have quite triangular head shapes: [![enter image description here](https://i.stack.imgur.com/VE10H.jpg)](https://i.stack.imgur.com/VE10H.jpg) However, the most problematic part of your description is the "impaling its prey" part. I assume you mean on some kind of rostral horn-like structures? Now, there are a bunch of reptiles which have such structures, namely male horned anoles and rhinoceros chameleons. Some snakes, such as the nose-horned vipers, also have small spikes on their noses. Despite this, using such a horn to catch prey would be pretty inefficient. For one thing, it's hard to strike accurately (as an analogy, would you rather fight someone by only punching them or only headbutting them?), and there's also the problem of transferring prey from horn to mouth. Your other answerer said that narwhals hunt like this, but that's an old hypothesis which has since been discarded. There is one way of impaling prey I can think of which would work: a really sharp tongue. Chameleons and some lungless salamanders already use ballistic tongues to catch their food, and cone snails do a similar thing with their radulae and actually impale the victim. For this to work out, the Jaculus would have to hunt small prey which don't move around much - medium-to-large sized insects, mostly, e.g. crickets, mantises... All that being said, it wouldn't make sense for an animal to use both strategies - leaping out of branches and firing a tongue. If the impaling part is important to you, the best compromise I can give you is that it just leaps/glides to get from A to B, and not to hunt. Going with that last option, I think the Jaculus would be a member of the Viperidae family, which uses leaping or gliding abilities to get around and a ballistic tongue, tipped with a sharp end, to hunt small prey. ]
[Question] [ The railgun utilizes two metal rails that, when under a electrical current, utilize the Lorentz force to accelerate a metal projectile to super sonic speeds. In light of this, Can the rails be replaced with plasma instead? Seeing as plasma also carries an electrical current, I wonder if such a design is possible, how it would work and what would its performance be. Edit: The way I envision such a system working is to use short range high intensity laser pulse to ignite the air to create the plasma and use that to launch the projectile before the plasma dissipates. The main reason for this is that while it is true that the plan ads would get blown out, it would be easier to repeat the cycle and have a consistent rate of fire instead of having to replace the rails after wear and arc damage. Of course this is my idea and I’m not sure this could work or if there are better designs out there. [Answer] > > Can the rails be replaced with plasma instead? > > > The wear and tear in a railgun is largely due to bits of the rails being replaced with plasma. Such is the result of striking an arc and running that much current through it. I had a think about a plasma-rail gun a while back and more or less discarded the idea, because what you end up with is the need to stabilise the projectile (so you shoot straight) and accelerate the projectile and retain the plasma rails for as long as it takes for the projectile to sweep through the barrel. You can't physically contact the projectile (because the arc will erode whatever you have in contact with the projectile, taking you back to square one) leaving you with the unenviable task of having three different and quite powerful electromagnetic effects in the same small volume all trying to do different things. That's not to say that you couldn't handwave the technical issues out of the way. I'd use a cold (non-thermal) plasma as the rails though, which will be much easier to interface with than the hot kind (you can stick your hands in a low-density cold plasma without will effects, for example). It does imply a fairly high level of technology, though. [Answer] Yes, it could, but the question is why. Plasma either destroys whatever it touches, or cools and stops being plasma when it touches things. So you need to do what fusion reactors do, and contain the plasma with powerful electromagnets, not just a durable container. But then you could just use the same magnets to push the projectile. Remember, whatever force the plasma applies to projectile will be applied to the plasma as well, and if you want to keep the plasma contained, the magnets must be able to counter it. So why not just cut out the middle man and use the magnets to push the projectile directly? ]
[Question] [ This can be considered a sister question to [this question.](https://worldbuilding.stackexchange.com/questions/157822/what-should-the-size-of-these-secret-superhuman-organizations-be) --- ### The Beginning Outside of Ser, the world was a chaotic and dangerous place. Ser was the only neutral country in a world filled with violence and devastation. In 1515, there were at least 8 wars going on and nobody had any alliances. All trade was cut off. The country Ser, led by an aging Empress Ana, was self-sufficient and had access to plenty of resources. She said: > > Let them fight, die, or whatever it is that barbarians do with one another. There is no need to intervene, so long as they do not cross our borders. > > > ### A New Emperor In late 1519, the Empress died from illness and her son gained the throne. He had a much different opinion of the world: > > The world is crying. Who will wipe its tears? Who is there to aid when all are possessed? > > > ### The Dominance Declaration In 1521, he declared war...upon everyone. He stated that he intends to rule all people and in order to do so he must unite all countries into a single government. It was a seemingly impossibly foolish move that would probably cause the destruction of the entire country. > > As of this moment, the Ser Empire will begin to liberate the people in the world burdened by their oppressive governments, who forfeited their right to yield power when they abused it. We will extend our hand in leadership towards these victims and one by one, we will unite all of mankind. This will be the last war. > > > ### Unified Enemies In response to this, nearly all of the countries that were all once enemies of one another forged temporary ceasefires in order to defeat the Ser Empire, whom they viewed as foolishly arrogant. They called themselves the "Truth Bringers." > > You are no God. We will bring to you this truth. > > > ### Winning the War In only four years, the Ser Empire managed to conquer all enemy territories while simultaneously defending their own from all attackers in every direction. --- Here comes the question part: The next section details how I explain the basic strategies of the war. I want to know just how realistic it is, or whether the Ser Empire would have actually been completely annihilated. --- During the war, the Ser government utilized the wars of other countries to its advantage, slowly gaining allies by promising regulated trade and by watching as the countries with temporary ceasefires turned on one another. For example, they deliberately conquered the region of Ferockana early on in the war because its government was already involved in four wars of its own, and this gave the Ferockana militia an incentive to fight alongside Ser in order to defeat their own enemies. In addition, Ser settled the disputes of conquered nations by offering compromised trade so that former enemies could fight together in newfound peace. With an exchange of goods or land that they previously denied each other, each nation profited significantly from the arrangement. --- Ser's main strategy involved conquering and negotiating. Basically, they show the enemy that they can't win. Then, instead of destroying the enemy, they said "Join us, and we'll do this for you." Not only that, but the Ser Empire promised to intervene in the conquered nation's affairs as little as possible, in addition to giving them access to resources that they otherwise would not have been able to get. They deliberately went after the countries that had the most to gain from joining them first, such as Ferockana which was in 4 wars of its own. > > Join us, and those four countries won't stand a chance. > > > They also went after the country that had advanced herbal medicine and medical technologies first, which in turn helped keep the soldiers healthier than the other invading armies. --- # How feasible is this strategy for world domination? Is there anything I am missing to make this work? --- Technology Clarification: Ser also had more advanced technology than the surrounding countries. The world was living similar to the 1500s, but the technology of Ser was probably similar to the 1700s. Guns that used gunpowder were not widely in use at the time but were still available. The Ser emperor pushed for the development of better weapons. For example, muskets were in use but were improved to allow quicker reloading and better aim. Ser also developed the first gun capable of shooting multiple projectiles simultaneously: it was originally called the scattershot, but was later called the shotgun. [Answer] I think that if you want things to work this way, you need more time between Ana's son ascending to power and him declaring war on everyone. If you give the empire just 2 years, not much will really happen. The peaceful, turtled up empire will struggle to transition to the war machine it needs to be to conquer the rest of the world. But with more time, maybe during Ana's illness to start with, the country can turn its old millhouses into weapon factories and training camps, start researching new technology to wage war (maybe an important breakthrough, like steampower (which seems appropriate for the time period you're talking about), would help propel them far in front of the neighbouring countries) and, most importantly in my opinion, start spying on the the other countries. This recon operation would allow them to gather important info on the terrain they're going to invade, field out the political situation and find rebellious (anti-war?) groups that could be potential allies. This period would probably have to last 10-20 years in total. It's fairly common to see a period of change start while the current ruler is ill and unable to control everything in their land. This could be a good starting point for Ana's son even before her death. But anything before 1527 would seem rushed to me. [Answer] You're missing the fact that leaders of opposing nations will recognize existential threats. Declaring war on everyone at once is a great way to bring this to their attention. Most times in history, especially in European history, if there is one major power that's clearly getting bigger and more successful in wars than any of the others, then all of its neighbors will band together to beat it back down to size. Not to annihilate it completely, mind you, but to just kick it back to the point where it is no longer a global threat to the entire continent. This is balance of power politics. Now it is possible that Ser could entice away one or two foolish rulers from a large coalition to join its side in the beginning, but if Ser was really making serious progress on dominating the world, any reasonable ruler would recognize the threat and throw in with the coalition. Also, getting nations to "join" Ser is not dominating them by any means. Especially if Ser promises them local autonomy; this would almost certainly have to include independent local military forces. If Ser "conquers" the world in this way, then these other nations could band together, declare themselves independent, and throw off Ser's pretensions of rule anytime. Countries that actually grew large and powerful in history did it by declaring war on neighbors one at a time. While being allied to other neighbors. This process usually takes centuries. Growing too quickly is also likely to trigger a coalition as a political backlash. [Answer] This is much more likely to work if Ser is playing both sides against the middle. Winning a game where you only control one side is hard. Your enemies do things you don't expect, or things that you did expect but didn't have any means to counter, or sometimes they just get damned lucky. Winning a game against multiple other sides is even harder, because you have to manage, predict and counter their interactions as well as their individual actions. Instead, consider the early 1500s. Bob, Ana's son and heir, is smitten with commoner Carol, who has a backstory that hopefully sets her at least a little apart from basic Cinderella, but is nonetheless not suitable marriage material for a future Emperor. Empress Ada, defying the trope that she is supposed to spurn the match and thereby turn her son against her, is secretly supportive. Carol is inducted into an obscure branch of the Sel military, and given training in combat and strategy. In 1519, shortly before the death of the Empress, she flees the country. A few months later, a remarkably talented sellsword Claire joins the army of Les, a nation slightly away from Sel, engaged in many of its own wars and eager to have the manpower. In 1521, Claire happens to be part of a patrol along the borders of Ferockana when Bob's declaration is made. In the following blitzkrieg-style invasion of Ferockana she distinguishes herself in protecting Les's interests, displaying a brilliant grasp of the optimal strategy on the battlefields against Sel forces. Ferockana falls, but the invasion is halted. Claire is thrust into the limelight. In times of conflict, military strength is political strength. Over the following months and years Claire excels herself, holding back the forces of the 'Great Enemy' Sel, whose technological and infrastructural superiority keeps them on the offensive, slowly expanding but not totally dominating. A grand coalition of Nations Against Sel slowly forms; it would have formed anyway and is far from united, but thanks to Claire's brilliant leadership it slowly fuses together coherently. Nations who do not join either Sel or Nas are ruthlessly crushed and subsumed by Bob's forces. Over a relatively short time, Claire's position as leader of the Nas armies (and increasingly their civilian structures) becomes absolute. Generals who advocate controversial tactics like attacking Sel's infrastructure, food production or supply chains, or trying to disrupt their coalition of alliances, either die tragically or are disgraced when their plans fail due to ambushes and counter strategies. Les is not an autocratic nation, but inevitably becomes one as the cost of war mounts. Who could be a better, safer choice than Claire to take the title of first Empress of Les? In the end, the war has consumed most of the major nations, and peace negotiations between Sel and Nas begin. Of course the best way of defusing future conflict is to join the thrones of the two nations in marriage. Bob and Claire both know it is their duty to marry for political advantage, not love. Once the alliance is made and the world has a short time to sort itself out again, a quick series of mopping-up actions against any unaligned small nations clears the board. Yes, technically it has two colours on it, and all the plebs can convince themselves that 'they' were on the winning side. [Answer] Of course, since it is your universe, you can set it up however you want. But some things that want to be explained. * Why was there constant war? It doesn't really seem plausible that nobody came up with the idea of diplomacy before Ser. Perhaps there's been a recent shakeup? Maybe there was some external force preventing war for a while, which allowed grudges to build, and that external force was removed? You could look at the strife that sometimes occurs when colonial empires leave, maybe. * Why was Ser able to avoid this battle royale? Sounds like they are pretty well off, and surrounded by angry neighbors. Ok, they have a huge tech advantage. Where'd they get it from? Why weren't they invaded when they were 10 years ahead of everyone else, rather than 200. * Why is Ser good at war? They have a tech advantage, but no experienced generals, all their tech is untested in actual battle, they haven't developed tactics. I'm assuming Ser is some sort of peaceful, enlightened place (given that they've managed to stay out of all their neighbors' wars). I think they need some significant internal strife, so they can have practice using their tech in wars. Some thoughts about solutions: * The existence of a big previous power would probably modify your world pretty significantly, so it might be a dead end. But it can go a long way in explaining "how'd this unnatural state come to be." Maybe they administrated the region is Ser sized blocks, and decided that Ser was their R&D center. * How cut off does Ser need to have been? Is it possible that, while they were a peaceful internally, they loaned their dudes out as high class mercenaries? This way they'd have some combat experience and local contacts. * I'm not really sure what the advantage of shotguns would be. Multi-projectile personal weapons aren't really used often in war outside of niche cases, IIRC. Why do they need to be shotguns? Assuming we're doing pike+shot, you have blocks of dudes with guns shooting at each-other. You are already producing a shotgun mechanism. Even more shots, but less energetic and smaller, doesn't seem like a huge perk. Instead give them rifling. Now they are really scary, because they can accurately place shots from way outside the range of their enemies. Also, longer ranges = classy high tech army in stories, usually. ]
[Question] [ In my world the „apocalypse“ dates back several decades and most people have settled down, the scavenging is left to professional adventurers who roam the less accessible and more dangerous ruins of a destroyed metropolis. I want to equip those adventurers with useful tools for scavenging while limiting the the equipment to the most important things to keep it as lightweight as possible and enable a character to work with the things he can actually carry on his body (walking back to one's vehicle several times just to produce everything he needs doesn't work for a film or game). (Some of) the tools should enable the user to defend themselves without carrying additional weapons against attacks from wild animals or primitive tribes (in fact many weapons originated from tools). Advantage: Compared to present-day burglars the scavengers don't have to be as careful - instead of carrying tools for lock picking one could simply knock down the front door. Consider: Fuel, gas (actual gas) and electricity are quite rare although who could rather come into possession of fuel and gas than the very people who scavenge the old world's remains... --- The very question is: # What are indispensable tools for professional scavenging? (Such as climbing walls, roping, prying doors or safes or walls and making ones way throught the debris.) Please additionally state, which other tools your suggestion would render redundand (e. g. carrying a crowbar there is no need for an additional welding torch or sledgehammer) and if it could be used (or modified) as a weapon. --- --- ## My ideas so far: * My main scavenger character carries a decorated crowbar, upside down, like a gentleman's cane. He is obsessed with ancient civilization he encounters on his raids every day. It can be used in battle like a crow's beak/warhammer, hooking hostile's legs to make them fall and as a pickaxe for climbing. * a small welding torch (that can be turned into a flamethrower by turning a switch to bypass the gas into an additional cartridge for inflammable liquids to spray those instead of burning the gas directly). * a grappling hook (for climbing/roping and swung as weapon to get a hold of enemies during battle) [Answer] [Clockwork hacksaw.](http://www.drlindseyfitzharris.com/2010/09/23/the-chirurgeons-box-the-clockwork-saw/) From a postapocalyptic character I dreamed up for this question, who sabotages a helicopter. [Primitive tribe fighting back against advanced military force?](https://worldbuilding.stackexchange.com/questions/110571/primitive-tribe-fighting-back-against-advanced-military-force) > > I was thinking about Hack's homemade hacksaw. It has a clockspring at > the base she can wind up. On triggering it moves the blade back and > forth a couple of mm, very fast. > > > Her hacksaw converges on a bone saw. A good metal scavenging tool which is why she carries it. Vibration amplitude can be adjusted depending on what she is cutting. For metal or bone minimal amplitude and maximum vibrations. For flesh, the opposite. --- Bow. Not too creative, but lightweight and versatile. You can shoot a light line and use it to pull up a heavy line that you can climb. You can launch flame arrows into dark spaces to light them up without going in and getting bitten. You can hunt. You can fight. You can make your own ammo. You can retrieve and reuse your ammo. --- Lobos. This is from World War Z - Lobo is short for "lobotomizer" and was a tool/weapon made (actually mass produced - 23 million of them) from the frames of cars. For a postapocalyptic fiction I like a thing that shows its provenance. I picture the lobos as being recognizably pieces of car frame, modified in a standard way. For your characters I imagine them as hybrid quarterstaff / crowbars. And they can be thrown like a javelin. --- Blast bottles. These are plastic bottles full of homemade gunpowder. Gunpowder can be made with primitive tech and plastic bottles would be great for keeping it dry and contained. Your demolitions character only uses Mountain Dew bottles, for her own reasons. Blast bottles can be used to open doors and dislodge things. Or you can wrap one with a chain, light it and throw it as a grenade. [Answer] Tomahawks A proper tomahawk has a hatchet blade counter-balanced by a small hammer surface on the back of the head. A steel tomahawk whose axe blade has a pointed beard (the part sticking down from the main axe blade) can also be used for prying. In one tool, you have a weapon, a hammer, an axe, a prybar, a skinning blade (hold the hawk by the hammer surface to scrape skin from a kill and then to scrape clinging meat from the hide), and a climbing aid (can dig the axe into wood to make the handle a hand-hold or use the beard to hook a ledge too high for you to reach. [Answer] ## Forget the crowbar, get a halligan bar. Scavengers are less like burglars and more like firefighters they just want entry as easily as possible, so look at what fire fighters and other rescue units use. [![enter image description here](https://i.stack.imgur.com/l7DtW.gif)](https://i.stack.imgur.com/l7DtW.gif) [halligan bars](https://en.wikipedia.org/wiki/Halligan_bar) are far more versatile than a crowbar and way better for getting through doors and walls. They were designed by firefighters to get into buildings fast without carrying a lot of gear. the metal cutting claw variety (see below) will break padlocks and tear open steel doors. So for entry with the minimum of additional tools it is perfect. It is the standard tool for forced entry, even the military often uses them. It does everything a crowbar does and a lot more. There is nearly nothing it can't be used to enter, especially if you have time. Since a wide variety of them exist, there is even believable a real ornate one actually exists your character could have found, firefighters sometimes give ornate axes as awards/memorabilia after all. [![enter image description here](https://i.stack.imgur.com/iAm1E.jpg)](https://i.stack.imgur.com/iAm1E.jpg) The other thing you need is a good backpack, you have to carry whatever you find afterall. A light source because abandoned places are dark, especially the areas in which anything is likely to still be valuable, head mounted for preference. but the best thing they could have is a partner, anyone who does demolition, fire, or rescue can tell you a compromised building is very dangerous. spend too much time in them by yourself and your luck will run out. Without aid you are just another corpse in the rubble. [Answer] Crowbar and Axe are the best frends of any scavenger. You can wear them both and they both are not bad weapons and have a lot of different usages. + knife - you shuold always have a knife of some sort with you in any kind of hiking even now. [Answer] A War Pick and Rope A War pick is essentially 1 side of a Pickaxe and 1 side of a hammer/axe. The pick side combines the advantages of a standard pick and crow bar. You can use it to help climb buildings, by stabbing the pick side into the wall. You can use it to destroy stones, rocks or metal contractions in your way. The metal pick will provide much greater penetration that a crow bar or axe and doubles up as an excellent weapon. You can also jam it into all sorts of cracks and use the war pick to leverage something out just as you would with a crow bar. The other side can basically be a hammer or axe, depending on your needs. An axe would be good for cutting things, a hammer would be good for building things. Either way, I would say this part is more of a style/situation choice for you to make. The next part is the rope. Rope is pretty damn important when spelunking or scavenging. Due to the war picks shape, you can use it as a grappling hook, by tying the rope to it,swinging it then throwing it. You would also use your pick as a ranged weapon, swinging and throwing it at opponents then pulling it back. Finally, you could use the rope to allow multiple people to apply force to the pick, so if you have a particularly stuck door, jam the pick in there, tie the rope to the pick and have your friends help you pull away. Bonus features * The head of the War pick could be detachable like some styles of hammers or axes. This means you can change the shaft length to make it easier to apply more force or use as a grappling hook. * It can double up as a cane if the shaft is long enough [Answer] If you are going to scavenge, you don't know what you may find that is valuable. So you must be ready for a lot of different situations. You would probably need enough tools that carrying them in a backpack would not be viable. I can think of: ## Tool box [![Men's toys](https://i.stack.imgur.com/mybbW.jpg)](https://i.stack.imgur.com/mybbW.jpg) Because it would absolutely suck that you can't get to the treasure inside the vault for want of a 1/8" phillips screwdriver. ## Swiss Army Knife [![Swiss army knife](https://i.stack.imgur.com/fs7wL.jpg)](https://i.stack.imgur.com/fs7wL.jpg) Opening and closing the toolbox all the time sucks. With this you can pick your teeth, cut a rope and open a can in a very practical way. ## Survival Shotgun [![Survival shotgun](https://i.stack.imgur.com/3onXv.png)](https://i.stack.imgur.com/3onXv.png) This guy carries a mini-tent, food and water in the butt [of his shotgun](https://www.instructables.com/id/How-to-Build-the-Ultimate-Survival-Shotgun/). He also carries condoms and a blanket there (seriously, go check). ## Cart [![They see me trolleying, they hating...](https://i.stack.imgur.com/zp8ZD.jpg)](https://i.stack.imgur.com/zp8ZD.jpg) You will want to bring that bounty home, right? Also helps carrying tools. ## Doggo [![Pet doggo](https://i.stack.imgur.com/0f9Ym.jpg)](https://i.stack.imgur.com/0f9Ym.jpg) A hunting companion that is also a friend and living alarm. Can also be trained to pull the cart and to find specific kinds of goods in the wastelands. Doubles as food when you run out of other edibles. ## Teddy bear [![TED](https://i.stack.imgur.com/n8Vt9.jpg)](https://i.stack.imgur.com/n8Vt9.jpg) Isolation can drive you mad. It's always nice to have someone to talk to, and the bear is more articulate than the dog when you eat the right pills. Also you've probably already eaten the dog. ]
[Question] [ The Dreel are a parasitic alien hive-mind from [The Return of Nathan Brazil](https://en.wikipedia.org/wiki/The_Return_of_Nathan_Brazil), book four in the Well of Souls series by Jack Chalker. Specifically, they are described as viruses which induce intelligence in their host, merging with the host's personality (it is unclear if they require already-intelligent hosts, or if an infection can become sapient all on its own), and altering it to serve the greater Dreel hive. So, how close to that can we get actually get with a plausible biological organism? An Anatomically Correct Dreel should 1. Be an intracellular parasite of some sort--not necessarily a strict virus, but extra brownie points for actual viruses or viroids. 2. Give the host the ability to recognize other Dreel. 3. Either alter the psychology of the host to be altruistic towards other Dreel, or (for extra brownie points) cause the host to become intelligent in the first place. [Anatomically Correct Series](https://worldbuilding.meta.stackexchange.com/questions/2797/anatomically-correct-series/2798#2798) [Answer] There are parasites which actually alter the behavior of their host to their advantage. * A parasite spending part of its life cycle into mice and then into cats has been shown to switch off the fear of mice toward the smell of cats, making the infected mice more prone to be eaten, thus passing the parasite to the cat * [Ophiocordyceps unilateralis](https://en.wikipedia.org/wiki/Ophiocordyceps_unilateralis) is a fungus making its host ant a zombie: > > Ophiocordyceps unilateralis is an insect-pathogenic fungus, discovered by the British naturalist Alfred Russel Wallace in 1859, and currently found predominantly in tropical forest ecosystems. O. unilateralis infects ants of the Camponotini tribe, with the full pathogenesis being characterized by alteration of the behavioral patterns of the infected ant. Infected hosts leave their canopy nests and foraging trails for the forest floor, an area with a temperature and humidity suitable for fungal growth; they then use their mandibles to affix themselves to a major vein on the underside of a leaf, where the host remains until its eventual death. > > > * a human parasite which spread through water pushes its host to soak their legs into water, where they can spread their eggs. Therefore is not implausible that the parasite alters the behavior of the host to react differently to the presence of other parasite into another host. This can be achieved by modifying the bodily odor of the host, for example. [Answer] While L.Dutch gave an excellent answer referencing a number of parasites that alter their host's behavior, none of these parasites fulfill the second criteria given in the question, that Drill should be able to recognize one another. Enter [Leucochloridium](https://www.wired.com/2014/09/absurd-creature-of-the-week-disco-worm/), a parasite that infects snails, but breeds inside the guts of birds. To get from snail to bird, it controls its host's behavior, making the usually nocturnal snails far more diurnal, as well as far more active. However, the parasite doesn't stop there. It then causes the snail's eyestalks to swell up and move in a manner resembling a caterpillar, one of the favorite foods of birds. This distinctly changes the host's appearance, making infected snails easily recognized. Your Dreel could employ a similar tactic regarding their host's eyes, or employ a different visual distinguishing mark. Therefore, it's pretty clear that it's possible for a parasite to both give a host a distinguishing marking and also change its behavior, and it follows that a particularly sophisticated parasite could alter its host's psychology to promote altruistic and cooperative behavior towards organisms with a specific marking the parasite creates, at which point all you need are hosts with a high inherent level of intelligence (for example, humans) and you effectively have your Dreel. [Answer] Deception, Reconnaissance, Evasion & Enhanced Logistics (D.R.E.E.L.) Originally designed as a cybernetic brain implant for military attack dogs, which granted its canine host a limited amount of cognitive enhancement and the ability to recognize each other and communicate remotely via implanted radio, the DREEL unit was the ultimate solution for battlefield intelligence gathering. Then Skynet became sentient, took control of all military hardware and started making its own enhancements to the implants. The latest versions can self-install themselves into any creature which they come in contact with. They offer human level intelligence enhancement and language, regardless of the limits of the original organic brain matter. With that intelligence comes combat training which greatly enhances the creatures abilities with their natural teeth and claws. Sensory enhancement is also available, however most animals are already much more environmentally aware than their human prey, so this enhancement option is rarely used. Fundamental to the Dreel unit's operation is a drive to pursue the new Dreel Agenda... Detect, Report, Enslave/Exterminate (human) Lifeforms Under this directive, the Dreel host * detects human survivors, * reports their location to Skynet by radio, * enslaves one of the survivors by jumping hosts, * exterminate human lifeforms either alone or with reinforcements sent by Skynet. ]
[Question] [ I have a species that I wish to create whose life cycle is similar to a Xenomorph from the Alien series. By this, I mean to create a species wherein: * A Xenomorph, or Species A, the base creature, by some method (egg-laying, birth, etc.), produces a Species B, a Facehugger * The Facehugger, by some other method, (parasitism in the movies), breeds the true baby stage of a Xenomorph, Species A. In the movies, the Facehugger implants a chestburster into a host that cocoons into a Xenomorph. My question is, is there any plausible way for a lifeform like this to be forced to evolve this way? I am fine with an advanced civilization engineering the ecosystem to push pressure into this kind of species, but I am wondering what factors might lead to such a species evolving, and if there are any close real life parallels. The end result being: Lifeform A giving birth to Lifeform B which then gives birth to Lifeform A's infant stage. [Answer] ## Alternation of generations "Lifeform A giving birth to Lifeform B which then gives birth to Lifeform A's infant stage": funny that this is exactly how the lifecycle of plants works. But then I have always said that plants are aliens. All plants exhibit an [alternation of generations](https://en.wikipedia.org/wiki/Alternation_of_generations). A [gametophyte](https://en.wikipedia.org/wiki/Gametophyte) produces gametes (eggs and sperm); when two gametes of opposite sexes merge, the results, as in animals, is a [zygote](https://en.wikipedia.org/wiki/Zygote), which will grow into an embryo. But here the similarity with animals ends: the embryo wil grow into a [sporophyte](https://en.wikipedia.org/wiki/Sporophyte), which will produce spores. Spores do not need fertilization (that's why they are called spores and not gametes). In suitable conditions, a spore will germinate and grow into a gametophyte, and the cycle will continue. [![A schematic depiction of the alternation of generations in plants.](https://upload.wikimedia.org/wikipedia/commons/thumb/8/80/Alternation_of_generations_simpler.svg/640px-Alternation_of_generations_simpler.svg.png)](https://commons.wikimedia.org/wiki/File:Alternation_of_generations_simpler.svg) A schematic depiction of the alternation of generations in plants. Drawing by [Peter coxhead](https://commons.wikimedia.org/wiki/User:Peter_coxhead), available on Wikimedia. Public domain. * In some primitive algae, the sporophyte and the gametophyte generations are equal, but this is boring, because the look alike. In land plants, the alternative generations are unequal and they do not look alike. * In mosses, the dominant generation is the gametophyte; the sporophyte grows (semi-)parasitically on the gametophyte and looks nothing like it: [![Moss sporophytes](https://upload.wikimedia.org/wikipedia/commons/thumb/d/d5/Macro_Photography_of_Moss_Sporophytes.jpg/640px-Macro_Photography_of_Moss_Sporophytes.jpg)](https://commons.wikimedia.org/wiki/File:Macro_Photography_of_Moss_Sporophytes.jpg) Moss gametophytes (the dominant generation, at bottom) and sporophytes (the tall stalks). Photograph by user Requestanaccount, available on Wikimedia under the Creative Commons Attribution-Share Alike 4.0 International license. * In ferns and seed plants, the dominant generation is the sporophyte. In ferns in particular, both generations are capable of independent life. A fern produces spores which germinate and grow into a [prothallus](https://en.wikipedia.org/wiki/Prothallium), which produces gametes (sperm and eggs) which, when joined into a zygote, will germinate and grow into a fern. [![The sporophyte generation of Onoclea sensibilis](https://upload.wikimedia.org/wikipedia/commons/thumb/2/29/Onoclea_sensibilis_3.jpg/180px-Onoclea_sensibilis_3.jpg)](https://en.wikipedia.org/wiki/Onoclea_sensibilis#/media/File:Onoclea_sensibilis_3.jpg) [!["Beads" (spore-bearing structures)](https://upload.wikimedia.org/wikipedia/commons/thumb/d/de/Onoclea_sensibilis_02.JPG/180px-Onoclea_sensibilis_02.JPG)](https://commons.wikimedia.org/wiki/File:Onoclea_sensibilis_02.JPG) [![The gametophyte generation of Onoclea sensibilis](https://upload.wikimedia.org/wikipedia/commons/thumb/4/4a/Onoclea_sensibilis_4_crop.jpg/180px-Onoclea_sensibilis_4_crop.jpg)](https://commons.wikimedia.org/wiki/File:Onoclea_sensibilis_4_crop.jpg) Left, the sporophyte generation of the bead fern, [Onoclea sensibilis](https://en.wikipedia.org/wiki/Onoclea_sensibilis). Photograph by user peganum, [available on Flickr](https://www.flickr.com/photos/peganum/7163941421/) under the Creative Commons Attribution-Share Alike 2.0 Generic license. Center, the "beads" (spore-bearing structures) of Onoclea sensibilis. Photograph by H. Zell, available on Wikimedia under the CC BY-SA 3.0 license. Right: the prothallus (gametophyte generation) of Onoclea sensibilis, with a young sporophyte growing (the frond on top). Photograph by user Peter coxhead, available on Wikimedia under the CC BY 3.0 license. * In seed plants, the sporophyte is the dominant generation. The gametophyte generation is tiny, very much reduced, and incapable of independent life. (Fun fact: pollen grains are not gametes, but spores. If they fall on a receptive stigma, they germinate and grow into a teeny-tiny gametophyte which will produce sperm cells to fertilize the eggs.) [Answer] Lots of animals, in particular certain species of wasps, use ovipositors to implant eggs into a host animal of some kind. These often have different appearances as they reach different stages of their life cycle. What you're more likely to see is something like this: * Adult stage of organism deposits eggs into host. * Larval stage of organism devours host from inside * (optional) Host uses shelled out carcass as cocoon before emerging as adult OR * Larval stage of organism emerges from host after consumption, to hunt more prey before pupating and moving into adult stage. The facehugger->Xenmorph->egg->facehugger change is bizarre, because the face hugger is a much simpler organism and is the one that emerges from the eggs, then ostensibly implants a larva or egg into another organism. It's a very overly complex lifecycle that doesn't really have any corollary. [Answer] ## It is one organism; the "facehugger" is just a complex first exoskeleton I don't think alternation of generations is necessary to explain this, since the facehugger phase doesn't really behave much like an independent organism - it does not eat, grow, or mate with other facehuggers. It is simply a complex original exoskeleton that is discarded once it is no longer needed. There are quite a number of parasitoids that have life cycles not entirely unlike the Xenomorph. Most of the time, the parent deposits the eggs close to the host if not injected directly through an ovipositor, or alternatively brings a host organism to the alreaminimizing the effort the larva needs to expend to pass to the host. However, a more complex, independent injection mechanism could be justified if the host organism and the adult phase of the parasitoid are not active at the same time. Perhaps they evolved together, but the hosts stopped being active in certain seasons due to climate shifts, and the parent could not guarantee that it would be able to procure food for the eggs by hatching time. This would encourage the evolution of eggs that could outlast the parent and hatch on their own when exposed to a nearby host, and also provide an advantage to larvae that were better at burrowing into their hosts independently. Perhaps they evolved as a more standard parasitoid, where the parent would provide the eggs with a paralyzed host but the larva would still need to burrow into the host on its own. It would only need the "burrowing" mechanisms in its first molt; once it had successfully implanted itself into the host it could shed these and begin its metamorphosis into its adult phase. As the burrowing mechanisms became more sophisticated and the larva more independent, they could eventually develop sensory organs for pursuing a host and injecting themselves into its gut directly. Alternatively, the facehugger was similar in form to the original larva, and the second molt became less sophisticated in order to make it easier for the first molt to inject it into the host. Note: This assumes that the Xenomorph evolved alongside its chosen host. An organism that can successfully parasitize a host from another planet is much less plausible. ]
[Question] [ I have been trying to design an offroad/all-terrain/rough terrain type vehicle for a story but i am split on what type of propulsion it uses. The vehicle i envision is supposed to be able to race and (quite literally) jump across sand dunes (like one would encounter in the Desert) and still be able to climb rocky terrain while having armor comparable to a light/medium tank and being able to carry a gun on the back having a caliber anywhere between an LMG and a light AA Gun (20mm) Wich would be best for such a vehicle? (and what would be the advantages one type has over the other?) P.S. If it matters, the military using this vehicle heavily favors speed in combat (think blitzkrieg on steroids, even the heavy tanks reach speeds above 100km/h) [Answer] It all depends on terrain type. My advice: pick your terrain type and find an human vehicle that operates in that terrain type. Low Pressure Tires Low pressure tires are fairly standard things. They're used on nearly all agricultural equipment and some unusual offroad vehicles such as the sherp. In my mind this is probably what you want. Low pressure tires work really well on soft terrains. Similar to tank tracks, they help distribute the weight of the vehicle, helping it to "float" on mud, snow, sand. In general, the bigger the wheel, the better. --edit-- Since the question now involves the military, you probably want tracks instead. --end edit-- In fact, I've picked a vehicle for you: the Sherp. The sherp is a vehicle that can go just about anywhere and drive over just about anything. It's fuel efficient, spacious, and for all that - it's only 44HP. How can a vehicle with 44HP be so good: big tires. * Sherp in the arctic: <https://www.youtube.com/watch?v=WrjjV6nGh0g> * Sherp vs really big american lifted trucks: <https://youtu.be/RNtZb4vWNLA?t=452> * Sherp 10x10 version: <https://www.youtube.com/watch?v=Y0CUo9eyw5c> However, the large rubber tires need to be in the operational range of rubber. So you're limited to temperatures between -40C and +80C or therabouts. Fine for earth. If you're on another planet, maybe not. If you're on earth and are looking to do an expedition across the middle of nowhere, well, that's what the Sherp was designed for. Mars rover style Mars rovers have what's known as rocker-bogie suspension and typically have thin metal wheels with spikes on them. There are many reasons for this. Rocker-bogie evenly distributes weight across all the tires. This means that it's less likely to get stuck on bumps. Metal tires have adequate grip on rocky/sandy surfaces, don't get punctures and a few other odds and ends. However, a mars rover sucks at high speed. They suffer from picking up the front wheel in sharp corners, the suspension doesn't absorb any shock (it conforms to the surface, but in a static way rather than a dynamic way). Mars rovers have motors in the hubs of the wheels. This means that the total energy output per wheel is quite small (If you had one motor six times bigger routed to all 6 wheels, a stuck wheel would get six times more power). This is unfeasible on a rocker-bogie suspension system. It's worth noting that having six small motors is better for redundancy. Bear in mind that some of the decisions about mars rovers are to do with the spaceflight there: lightweight, surviving a vacuum etc. I can't find any videos of mars-rover-like man carrying vehicles, so here's another fully articulated vehicle: <https://www.youtube.com/watch?v=OXQZMmCvTEg> It isn't winning any contests unfortunately Tank Tracks Tank tracks are heavy, complex and have many moving parts. The places they excell are where the ground is soft. A tank track spreads the weight over the vehicle over square meters of terrain. This offers big advantages in mud, snow and similar surfaces. Tracks can be made from metal or have spikes/cleats to dig into hard materials. This is what makes them good for sno-cats which drive on ice. However, tank tracks have issues with manouverability and energy loss. Moving a tank track takes a lot more energy than moving a wheel because it all has to flex and bend, and when you turn, that huge big contact area with the ground is now fighting your efforts to turn. If your vehicle is light enough for low pressure tires, take those instead. Lower pressure tires are simpler, lower maintenance, and just about as good in terms of getting over things. If your vehicle needs 50 tonnes of Armour and maintain off-road capability, go with tracks. Just be aware that it'll impact your vehicles fuel efficiency a lot. High Pressure Tires Similar to low pressure tires. High pressure tires can carry heavier loads than low pressure tires, but they start to suffer from sinking in to to surface. However, they require less maintenance than tank tracks, and that's why they're used for high-payload mining trucks. Legs Legs are, strange. On humans they allow us to do everything from swim to crawl to walk. It seems like they'd be ideal on vehicles. Unfortunately making walking vehicles is hard. They tend to be slow, weak and not that great off road. They concentrate all their weight on really small points, so sink into most terrain. If you're only operating on rock, legs may be an option. They do have the cool factor! * A man-carying walking vehicle showing just how slow these things are: <https://www.youtube.com/watch?v=1sRlFQLwg3w> * Here's one from 1969: <https://www.youtube.com/watch?v=ZMGCFLEYakM> * Modern robots like Big Dog are pretty cool, but we haven't solved the energy-source issue when scaling this sort of thing up. <https://www.youtube.com/watch?v=LJZQ3n-iQYE> * Bipedal mech: <https://www.youtube.com/watch?v=3ldJswGpkjY> Driven by external power though. Probably draws enough power to make an on-board electrical source impractical. Boats Boats work well on the ocean. Like, really well. They suck on land though: <https://www.youtube.com/watch?v=6Tp90AnMaos> Hovercraft Unfortunately hovercraft generally suck(tm). They can't go up hills, they get stuck on small obstacles, they are noisy and consume a lot of power. Others Have a browse of <http://www.unusuallocomotion.com/> to see just how strange the vehicles we can build are [Answer] Given your clarifications, I'll just simplify this and say go with tracks. Wheels don't do fast in sand very well because they they don't have much surface area. Instead of pushing against the terrain, they mostly just send the terrain flying backwards wasting lots of fuel and energy. Tracks however can distribute the force of the wheels much better maintaining traction. Also, and they don't carry the weight of armor and heavy firepower as well. All that weight would push your wheels so deep into the sand that you'll just get stuck. Since this is a military vehicle, the resilience of tracks when being shot at should also be a determining factor. All this said, many tanks are beginning to go towards bullet proof wheels for better highway speeds and fuel efficiency than tracks, but this is mostly just because more and more fighting is being done in urban environments where roads are smooth, hard, and reliable. Tanks designed to fight in deserts, swamps, etc. still do better with tracks. ==== But there is a problem... the fastest production tank ever built maxed out at 82kph on good terrain; so, it probably still won't be hitting your 100kph desires on sand; so, you'll need to some up with something that does not really exist yet to get to 100+ kph. If you don't mind delving into more exotic methods of transportation look at hydrofoil jet boats. Most hydrofoil warships can reach speeds of ~80-90kph with some newer ones like the W-18 Interceptor which tops out at 110kph. While boats "theoretically" suck on land, sand is a bit of a special medium. When bombarded with sonic waves, it acts a lot like water; so, a sand-boat could possibly be designed that shoots the sand ahead of it's hydrofoil with a sonic device liquifying the sand, then uses jet engines to let you ski over the sand-dunes like they are water at unnervingly fast speeds. So your sand tank/boat/jet/somethings would basically look like this, but on sand: [![enter image description here](https://i.stack.imgur.com/g4UP3.png)](https://i.stack.imgur.com/g4UP3.png) I won't do rocky very well at all though; so, it will come down to the question of whether you are going for top speed or maximum versatility. [Answer] This is Boston Dynamics [BigDog](https://www.youtube.com/watch?v=W1czBcnX1Ww). It's a 4-leg robot that can walk, run, climb stairs, gallop on a treadmill, and recover from being kicked in the side. One model is powered by a small engine about the size of a motorcycle engine. This thing could be scaled up. It could have assist legs that got it standing when it was carrying a specially heavy load. It could have the ability to brace against terrain when firing a heavy gun. Top speed could be pretty fast over good surface. Maybe not as fast as a car, but faster than a tank-tread type vehicle. It could have a good range on a tank of fuel. It could fairly easily be customized for different purposes. One with less armor, longer and wider-set legs, and room for passengers could be a personnel carrier. Heavy short legs might be a heavy equipment carrier. Stripped down to basics and long springy legs like those things that amputees use to compete in athletics, it could be a scout. Expandable feet might make it able to walk on quite soft ground. Conceivably it could be made amphibious. Maybe add water proofing and a snorkel. Give it some specialized probes and it's a mine sweeper or bomb sniffer. Give it some grippers and such, and it might climb quite steep cliffs. Probably you would want to combine with a variety of other vehicles to cover the things that it has trouble with. For those exceptionally heavy loads you still want tank treads. When you get some good roads you probably want wheels. And when it absolutely positively has to get there as fast as possible you need something that can fly. [Answer] Motorcycle with armored fairing. You want desert and you want fast. You want to catch air. You want a motorcycle. But you want armor. OK; give it an armored fairing. [![Sportmax 1955](https://i.stack.imgur.com/a4gpB.jpg)](https://i.stack.imgur.com/a4gpB.jpg) <https://en.wikipedia.org/wiki/Motorcycle_fairing> Here is the sweet Sportmax from 1955. A fairing can be extended up over the driver to protect from dust and rocks. It is not going to protect from mines or shells like the armor on a tank but it will give a modicum of protection against bullets. The idea can be that your armored bike is so light and has such a small footprint it will not set off mines. Your driver can ask about shells and be advised to stay away from those. A problem: will the driver be too busy driving to lay down fire? One could have a rider and a second rider as gunner but that gets crowded and ruins the aesthetic. I like the idea of a semiautonomous droid gunner on the cycle - sort of like R2D2 with a gun. It could be called Gun, or Gunny. Gunny can swivel its barrel thru a hemisphere of positions and - surprise - rotate down and shoot across under the cycle when events warrant. Exchanges between rider and Gunny would be fun to write! [Answer] # Low altitude aircraft or hybrid design Driving a (real life) tank across rough terrain at full speed already takes a certain degree of skill. At the speeds you propose, keeping a land vehicle stable enough for the gunner to hit anything (and not crashing in the process) while going over rocks and steep hills seems like a tall order. No matter how low your center of gravity is, bumping into a rock at 100 km/h is going to ruin your day. Also, the kind of suspension required for jumping is quite different from what you'd use on a vehicle that's designed to go fast. Oh, and neither your suspension nor your crew will react particularly well to the stress of 50 tons hitting the ground after a fall of several meters. I'm not saying that it can't be done, but it sounds more like something a renowned stunt driver would attempt on television than an effective military tactic. Legs might mitigate a lot of the issues, if your tech base is really mature, but they're not going to be efficient enough to handle your vehicle's mass and speed at the same time. If speed is key, and terrain is an issue, you fly. While current doctrine doesn't favor heavily armored aircraft, a 20mm gun and medium armor are well within the limits of what such a vehicle could carry. It would not be the most efficient in terms of maintenance cost and fuel consumption, but could extend its operational range by driving where terrain permits it, and lifting off only to engage or to cross difficult terrain. It would easily outmaneuver any land vehicle, though. [Answer] If the terrain is soft but fairly smooth (like plowed fields, or forest floor), a tread -- possibly more like a tractor than a tank -- will get better traction and flotation. If it's primarily an issue of bumps and unevenness, rolligons (see the Landmaster that's the best thing in Damnation Alley the 1970s movie) will do better; they'll also handle extreme soft (as in more liquid than solid) better than treads, and can act as paddle wheels if things are so soft your vehicle is floating. They can run faster than treads, can be steered like wheels (steering the entire rolligon assembly as if a single wheel), and tires can be changed much like conventional tire/wheel units (plus, if provision is made to lock the rolligon from rotating, they can run with a flat as if nothing was wrong). If you can combine a rolligon with very wide, very soft tires (or driver-controlled variable pressure tires), you can probably get the best of both. ]
[Question] [ I understand an interstellar dust cloud as "an accumulation of gas, plasma, and dust in our and other galaxies. Put differently, an interstellar cloud is a denser-than-average region of the interstellar medium, (ISM), the matter and radiation that exists in the space between the star systems in a galaxy." (I'm assuming it would be possible for Earth to cross one of these interstellar clouds, but tell me if I'm wrong, please) [Answer] Probably nothing at all as a "dense" cloud of matter in space is still not nearly as dense as planetary atmospheres surrounding an earth like planet. Those pretty pictures of nebulas that you see are spanning areas of multiple stars, each likely to have some planetary orbits. In fact, any video game in which space is colored in some way to show it's in a nebula is not realistic. You would see the same black field of space if you were looking out from a nebula as you would see looking into it. In fact, the NASA photos you see with pretty colors are artificially colored to represent differing parts of the non-visible light spectrum and the general areas of concentration of a particular chemical or a composite of both renderings of non-visible light and chemical composition. Nebula aren't visible to the human eye unassisted and the visibility that radio or other non-visible spectrum telescopes can see is only because we are looking at a massive area of space from a massive distance away from said area. Edit: Forgot, by comparison, the Asteroid Belt is the densest area of space that is closest to the Earth and is filled with massive rocks of various land mass sizes... It's also not a hindrance for space ships passing through it, as the gaps between these rocks are typically wider by orders of magnitude when compared to the rock. If you're lost at sea in a life boat, you could find a small island eventually... But you'll find a lot more stretches of ocean surface before shouting Land Hoe! Even in the Pacific, which is the ocean with the densest concentration of islands.... It's still got a lot more "not Islands" that you're far more likely to go from the Americas to Asia and never see a single one unless you specifically know where to look. [Answer] Any interstellar material would be redirected by the Heliopause in the Heliosphere (<https://en.m.wikipedia.org/wiki/Heliosphere>). The solar winds travel for a pretty long time and only get slowed down at the Heliopause (or mark the Heliopause by slowing down there, if you want to look at it that way). Besides creating a strong magnetic field, which deflects interstellar ions, the density of particle interaction would lead to the deflection of most uncharged interstellar atoms as well. If an interstellar cloud was able to get a detectable amount of matter towards Earth, it would be pretty bad news. I guess the upper atmosphere would be getting stripped away, continuing with lower parts of the atmosphere, then mountains depending on the density. Like using rougher and rougher abrasive paper on wood. EDIT: Okay it seems like only large scale objects can surpass the Heliosphere. Interstellar dust gets electrically charged after passing through the Heliopause and deflected by the lorenz force. An insterstellar dust or gas cloud could never damage earths atmosphere due to this effect. (arxiv.org/ftp/arxiv/papers/1107/1107.0283.pdf Page 3, "Between the heliopause and termination shock,...") (If large scale astroids are contained inside the interstellar gas/dust cloud they could, as mentioned, travel to earth and damage it, if they are considered part of the cloud.) ]
[Question] [ I am part of a group of immortals from the planet Ziest. From the dawn of time we came…moving silently down through the centuries. Living many secret lives, struggling to reach the time of the gathering, when the few who remain will battle to the last. We immortals unfortunately cannot create progeny, as our bodies cannot produce the sex cells necessary to make offspring. However, recent technology have allowed immortals to become surrogates, allowing them to pass on their immortal genes to the next generation. A fertilized egg from two mortals is put into the womb of a female immortal, allowing it to gestate there. During pregnancy, placenta separates the baby’s and the mother’s DNA. When the baby forms in utero, the placenta forms along with it. The primary purpose of the placenta is to be a gatekeeper. It provides the growing baby with nourishment and sustenance, and is one of the main protectors of the integrity of the fetus. Only specific matter can go through to the baby, meaning that the DNA of the carrier stay on the other side of the placenta. This is meant to protect both parties, as too many cells passing between mother and child can be dangerous to both. How can this be modified to allow the surrogate to pass on their genes without endangering the lives of the carrier or child? [Answer] You could change the premise of infertility in the immortals of Zeist from an inability to produce sex cells, to the cells being produced being dud/defective due to an inherited disease of the nuclei. Once you establish the above, you can then use the technique of [three parent baby](https://en.wikipedia.org/wiki/Mitochondrial_replacement_therapy) (used in real life) to allow for transfer of the nuclei in the reproductive cell, which will ensure that the mitochondrial DNA of the immortals of Zeist gets transferred to the babies. Next, you need to establish that the mitochondrial DNA is source for some of the pecular traits of the immortals of Zeist, which can now be inherited with advances of technology. [Answer] The children are chimeras. In our world, cells from a fetus can move thru the placenta and take up long term residence in the mother. <https://www.scientificamerican.com/article/scientists-discover-childrens-cells-living-in-mothers-brain/> > > The physical connection between mother and fetus is provided by the > placenta, an organ, built of cells from both the mother and fetus, > which serves as a conduit for the exchange of nutrients, gasses, and > wastes. Cells may migrate through the placenta between the mother and > the fetus, taking up residence in many organs of the body including > the lung, thyroid, muscle, liver, heart, kidney and skin. These may > have a broad range of impacts, from tissue repair and cancer > prevention to sparking immune disorders. > > > It is remarkable that it is so common for cells from one individual to > integrate into the tissues of another distinct person. We are > accustomed to thinking of ourselves as singular autonomous > individuals, and these foreign cells seem to belie that notion, and > suggest that most people carry remnants of other individuals... > > > It is easy to detect male cells in a female because you can look for cells with a Y chromosome. There is no reason to doubt that the exchange is reciprocal - mother cells moving in and taking up residence in the fetus. This is how your immortals pass on their genes. Their cells move thru the placenta and take up residence in the growing fetus. Immortal cells in residence then gradually and gently compete for space with the cells of the native human, taking advantage of the scaffolding grown by the fetus and gradually edging out the natives over time. It might take a lot of time but eventually the individual is effectively a clone of the "surrogate", with the mortal cells of the original having died out over the decades. [Answer] Have you considered somatic cell nuclear transfer aka cloning? No need for sex cells from two mortals, just take a mortal egg cell, remove nucleus and replace it with a nucleus from an immortal somatic cell. The capability to use this technique of course depends on the scientific level of your immortals, we humans have so far only cloned Dolly the Sheep and some macaques. Also, cloning of humanoids might be a moral issue. Second thing that came to mind reading your question is the viability of immortals to be surrogates. Lacking the ability to produce sex cells, why would female immortals have a menstrual cycle or even any capability to form uteral lining to grow a fetus? This is something you might want to consider. Considering your question aka how can a surrogate mother give the fetus she is carrying her immortality. As previously @Willk has pointed out, microchimerism is known to happen both fetal to mother and mother to fetus in placental mammals, including humans. However, little is yet known about this phenomenon. <https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5532073/> This article might be a heavy read, but the key points in the end summarise it nicely. (The article also touches the issue of immune tolerance in expecting mothers, which might also be of interest to you considering your surrogate mother carrying a different species, but this was not the question). The conclusion is that we don't know what types of cells are passed on to the fetus during pregnancy. After quickly glancing over a few other abstracts on the matter, the scientific evidence seem to point to the conclusion that mother to fetus microchimerism happens to help the child's immune system mature into something more complex than it would without this phenomenon (sorry, english third language). For me, as a person who likes to pretend to know something about human biology and immunology, it seems like a little bit of a stretch to think that the surrogate mother could pass on stem cells to the fetus it's carrying, and that the stem cells could replace all the cells of a fetus without causing a immune reaction and downright rejection by the child's immune system. But, we also have a story with immortals and as I said, the research is incomplete, so what the hell. However, while researching this, I also came across the info that different types of immune cells are passed on to a baby during breastfeeding... at least in mice. So I thought that if you formed your reason for the immortals' immortality around their different immune system, you could explain that the effect of the surrogate mother on the child's immune system both during pregnancy and while breastfeeding would compound into the child getting immortality through immortal-like immune system. This system could also cause a different level of immortality. TL;DR 1. cloning 2. maternal microchimeric stem cells in fetus/child somehow evading immune system and replacing all other cells over time 3. immortality because of immune system + motherly effect on child's immune system during pregnancy, breastfeeding (and a tad growing up) I hope I didn't fall to much into the realm of discussion, I'm new to this website. :) ]
[Question] [ In this world, a progenitor has created a mass of order out of chaos, with the possibility of entropic fluctuations increasing the further out from the center you get. What do I mean by entropic fluctuations? I mean that earthquakes, shifting gravity, and brief dissolution become more and more likely the further out you get. Livestock on the edges need wings to avoid being tossed up and splatted by shifting gravity or falling off a cliff/engulfed when earthquakes occur. While raw vacuum is never introduced for more than a split second, air pressure might fluctuate due to the violation of earth and sea. Imagine massive amounts of energy pulling things apart and the resulting whoosh of air filling that space. But that brings me to my question. Part of the reason that oceans were where life began on Earth is because of the ocean's relative inviolability: once you get a couple hundred feet down, the temperature, pH, and medium (water) don't change much. What kinds of adaptations would sea creatures need to survive earthquakes, gravity shifts, and brief but sudden introductions of void (possibly cavitation)? [Answer] If unpredictable risk of death is high then R strategists are favored. R strategists have lots and lots of offspring but don't invest much time or energy into each individual offspring. R strategist reproduce quickly and tend not to have long lifespans. You will not see things like whales or sea turtles, creatures that take a long time to grow up and reproduce. You can still have big old creatures but they will be like lobsters, things that never stop growing and can reproduce fairly quickly. Without more detailed information this is about all the information I can give. [Answer] Creatures would evolve a variety of mechanisms: * Some would be able to sense impending disasters and escape ahead of time * Some would be able to dodge or move faster than disasters * Some would be able to endure disasters with armor or resistances * Some (and this is my favorite) would be to regenerate many individuals from their broken apart and damaged pieces and use it as part of their reproductive cycle ]
[Question] [ There's a lot of talk on futurist blogs about mining asteroids for propellant and other resources for space travel, but I have something else in mind. Could a spaceship, starting out in geocentric orbit, somehow grab onto an asteroid with a highly elliptical orbit and use that asteroid's momentum to toe the craft out into heliocentric orbit? The biggest problem with this idea is the enormous difference in relative speed between the spaceship and the asteroid - it's hard to imagine any way the spacecraft could physically interact with the asteroid that wouldn't result in the immediate annihilation of the craft. Perhaps some sort of magnetic device used on a metallic asteroid? If safety is a concern, would this be possible for an unmanned cargo craft? [Answer] Let the asteroid accelerate you slowly. 0: Spot incoming asteroid. Call out "Asteroid ahoy!" 1. Get in position near asteroid's path. 2: Harpoon asteroid with cable. You have a railgun harpoon which you will use for other reasons later in this story. 3: Pay out cable such that you are accelerated at your tolerance and lengthening cable accommodates the difference in relative speeds. 4: You will eventually be going the same speed as the asteroid, at the end of a long cable. 5: Reel yourself in to the asteroid if you like. You are on your way. [Answer] Obvious problem: there doesn't seem to be a reliable supply of earth-crossing asteroids that frequently pass sufficiently close to earth that you could make your manoever. This is a good thing for life on earth as a whole. Secondly, magnets won't help you much; you might get a small boost, but the strength of a magnetic field drops off too quickly with distance and the target is flying too fast to be in range for long. Either you accelerate massively quickly (possibly smashing your ship and liquifying the meat cargo in the process) or you won't get much benefit. Lastly, close interceptions with massive objects with relative speeds measured in many kilometres per second sounds like a really risky sort of thing to do. Rather you than me. [Answer] The way to go is to make a close fly-by, the way deep-space probes pick up speed by passing major planets. If you do it right, you can add up to twice the asteroid's orbital speed to your velocity. This would require making a tight elliptical orbit past the asteroid, seen from the asteroid's frame of reference. This will make your ship leave at the same speed it entered orbit, just in the (nearly) opposite direction - again, seen from the asteroid's frame of reference. Seen from your spaceship's original frame of reference, you will now be whizzing ahead of the asteroid at twice it's speed. The way to go about it is to go as close to the asteroid as you dare when it passes, allowing you to slingshot yourself around it. This would require very little fuel, but very precise maneuvering. You would not need a very big asteroid, just one that is a good deal heavier than your spaceship. Too small, and you will slow it down as you speed up and hence not get the full benefit. A solid rock 10 to 20 meter in diameter would probably do the trick. Such rocks often pass close to Earth. In 2018 alone, 93 asteroids were detected passing Earth within the Moon's orbit, though many were only a few meter in diameter. ]
[Question] [ Melange, also known as "the spice", is a fictional drug in Frank Herbert's famous Dune series, which has many benefits (and some drawbacks). In this series of questions, I'll try to see how many of its properties a single, consistent substance could plausibly have at once. These effects are: * Increased lifespan * Expanded sensory awareness * Prescience (we'll leave that one aside for now) * Eyes being stained blue * Addiction * Mutation Other things of note include that withdrawal from consuming melange is fatal and its production. Kind of a Dune spoiler: > > When the excreted waste of young > sandworms mixes with water, it forms something called a pre-spice mass. Pressure causes the pre-spice mass to rise to the surface, where exposure to the sun and air turns it into melange. > > > --- So, the first of these questions will deal with the source of melange. How exactly would the chemistry of the above process work? If it would work at all, that is. Are there any real-life examples of things which happen similarly? If it ends up being implausible, I'll accept the closest you can get. [Answer] One example of the formation of chemical compounds by terrestrial entities that results in an eruption are bacteria in a swamp. The bubbling of swamp gas to the surface is the result of the accumulation of methane and or CO2, excreted by bacteria as they digest their food. These processes under very certain conditions can result in Limnic eruptions when the gases dissolve slowly into the water at the bottom of deep lakes -- where the pressure is high and the temperature is low. Once the concentration reaches saturation, the small kinetic events can cause the gases to come out of solution and bubble to the surface. The results can be catastrophic. [Answer] The process to produce complex organic chemicals are endless, you will have to decide what makes it in your story. Your only real constraint is it is produced by an organism. For examples you can use most real world drugs and spices. Penicillin is produced by a fungus, cinnamon and aspirin are tree bark, There is a whole slew of drugs made from [hamster ovaries](https://www.health.qld.gov.au/__data/assets/pdf_file/0024/147507/qh-gdl-954.pdf), the list is endless. The effects are fictitious if we knew chemical that would extend lifespan we would be making them. But thats fine the effects of a drug are nearly impossible to predict based on its origin, unless it is the same effect the original organism uses it for such as antibiotics, which is not the case here. Keep in mind "spice" might not be a single molecules but a naturally occuring compound of several different chemicals. [Answer] Wild take: Humans are actually (distantly) related to the sandworms. Melange doesn't need to be a very complex compound that just so happens to be compatible with the human organism in a way that enhances it. Because the set of sophisticated instructions for all those cool things melange allows for is actually stored in the genetic code of the one consuming the melange. Melange is an hormone that triggers development of the neotenic humans into something more like a Guild Navigator, because much of the genetic program for that is still dormant in humans and every cell in the human body is waiting for that chemical signal that the ancestors of humans used to produce on their own. Eye cells are waiting for melange to give them the go-ahead to start synthetizing blue pigment, neurons are waiting for melange to unblock psychic powers and the bone marrow is waiting for melange to produce stem cells and to put them in the blood to rejuvenate the body. Humans are like caterpillars that evolved away from becomming butterflies, and melange is the fix. ]
[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. Closed. This question is [off-topic](/help/closed-questions). It is not currently accepting answers. --- Closed 4 years ago. * This question does not appear to be about worldbuilding, within the scope defined in the [help center](https://worldbuilding.stackexchange.com/help). * You are asking questions about a story set in a world instead of about building a world. For more information, see [Why is my question "Too Story Based" and how do I get it opened?](https://worldbuilding.meta.stackexchange.com/q/3300/49). [Improve this question](/posts/150127/edit) I'm a sci-fi world builder, and I was recently reading Charles Stross's sci-fi/space opera novel Singularity Sky for inspiration, and I noticed some interesting but scientifically dubious worldbuilding. In the novel, ships are built around a electromagnetically charged black hole. These black holes provide power (at least 20 gigawatts) and propulsion, when fed a steady stream of particles, an artificial gravitational field that can be manipulated, and (through technobabble) faster-than-light travel. According to the book, the "kernels" are approximately 8 billion tons and electron sized. My questions are: Would a black hole of this size and mass be able to provide that much power, and if so, what possible method exists to create one? This is a bit of an open ended question, so I'm looking for the best answer. Secondary question: how far away would you need to be from the black hole to experience one g? Would it be possible to construct a ship around the black hole at that distance? [Answer] All black holes are theoretically predicted to emit [Hawking radiation](https://en.wikipedia.org/wiki/Hawking_radiation) due to quantum effects, and the black hole's [luminosity](https://en.wikipedia.org/wiki/Luminosity) (the total power of the radiation it's emitting) depends only on its mass, the smaller the mass the greater the luminosity. There is a calculator on [this page](https://www.vttoth.com/CMS/physics-notes/311-hawking-radiation-calculator) which allows you to enter in one parameter for a black hole like mass, and see the result in terms of other parameters like the black hole's radius and the luminosity of its Hawking radiation. If you select "metric tons" for the mass units on the menu and "MW" for luminosity, then it seems the numbers you quoted are not quite right. 20 gigawatts would be 20000 MW, and if you type that for luminosity and hit enter, you find that the black hole should have a mass of about 1.33E8 = 133 million tons, whereas 8 billion tons would mean a luminosity of only 5.57 MW. The 133 million ton black hole would have a radius of about $2 \* 10^{-16} $ meters (about 14 times smaller than the [classical electron radius](http://scienceworld.wolfram.com/physics/ElectronRadius.html) of $2.8 \* 10^{-15} $ meters), while the 8 billion ton black hole would have a radius of about $1.19 \* 10^{-14}$ (about 4.25 times larger than the classical electron radius). I just had a look at Singularity Sky and it didn't actually say the 8 billion ton black hole was the sole source of energy--p. 76 suggests its main use is to generate a "jump field" for FTL travel as well as some idea it could be used to generate ordinary momentum via "complex tunneling interactions" (both ideas assume fictional future physics, presumably). Then the author adds "The kernel had a few other uses: it was cheap source of electricity and radioisotopes". So it could be the ship has other power sources. Also, since power is energy per unit time, even if the black hole was the ultimate power source it could be that it's sometimes used to build up energy in some kind of battery or capacitor, which can then release that energy at a faster rate (and thus greater power) than the black hole, for a short time. The scene mentioning a figure of "twenty gigawatts" was on p. 249 when the ship released an intense laser burst, so there's no suggestion the ship generates this much power routinely. As for constructing it, a [kugelblitz](https://en.wikipedia.org/wiki/Kugelblitz_(astrophysics)) is a black hole created by radiation (as from a gamma laser), not a separate phenomenon. By the [no-hair theorem](https://en.wikipedia.org/wiki/No-hair_theorem) in classical general relativity, the only traces of the matter/energy that formed a black hole are mass, charge, and angular momentum, beyond that there should be no traces of what formed it (in quantum gravity there might be subtle information about what formed it that could be found by detailed measurement of all the particles emitted as Hawking radiation, but this wouldn't matter in terms of broad variables like gravity or luminosity). As for the question about gravity, I've worked it out below, but you can skip to the bolded sentences if you just want the final results. If you are "hovering" at a constant distance r from a black hole of mass m (in terms of [Schwarzschild coordinates](https://en.wikipedia.org/wiki/Schwarzschild_coordinates), whose physical meaning I discussed [here](https://physics.stackexchange.com/a/146611/59406)), rather than orbiting or falling or otherwise moving in Schwarzschild coordinates, then the [proper acceleration](https://en.wikipedia.org/wiki/Proper_acceleration) you experience, which corresponds to the gravitational force you would measure in your local region using a scale or [accelerometer](https://en.wikipedia.org/wiki/Accelerometer), would be given by the formula on the bottom of [this page](https://books.google.com/books?id=reQ7DQAAQBAJ&lpg=PA53&pg=PA53#v=onepage&q&f=false): $$a = \frac{m}{r^2}(1 - 2m/r)^{1/2}$$ $1/r^2= r^{-2}$ is equivalent to $r^{-3/2} r^{-1/2}$, so we can rewrite this as: $$a = (m r^{-3/2}) (r (1 - 2m/r))^{-1/2} = (m / r^{3/2}) (r - 2m)^{-1/2}$$ As is common in general relativity textbooks, this is expressed in "geometrized units" (see p. 4 [here](https://www.seas.upenn.edu/~amyers/NaturalUnits.pdf)) where the gravitational constant G and the speed of light c have been defined to equal 1 so are not included, but someone calculates [here](https://www.physicsforums.com/threads/acceleration-at-the-event-horizon.72687/) that the above expression in geometrized units is equivalent to the following non-geometrized expression: $$a = (G m r^{-3/2}) (r - r\_s)^{-1/2}$$ Where $r\_s$ is the [Schwarzschild radius](https://en.wikipedia.org/wiki/Schwarzschild_radius) for the black hole, given by $r\_s = \frac{2 G m}{c^2}$ The above equation can be rearranged as: $$\frac{a}{Gm} = (r^3 (r - r\_s))^{-1/2}$$ and if you put both sides to the power of -2 you get: $$(\frac{G m}{a})^2 = r^3 (r - r\_s) = r^4 - r\_s r^3$$ Now if you wish, you can set the desired proper acceleration a on the left side to equal one g, or 9.8 m/second^2, and then with the gravitational constant as 6.674 \* 10^-11 meters^3 / (kg \* second^2), if you have the black hole have a mass of 133 million metric tons = 133 billion kg (what was needed for a luminosity of 20 gigawatts), the left side of this equation will be equal to 0.82 meters^4. And I already found using the calculator that the 133 million ton black hole would have a Schwarzschild radius of $2 \* 10^{-16}$ meters, so then to find the radius $r$ where we have one g acceleration we just solve for r in this equation: $$0.82 = r^4 - (2 \* 10^{-16}) r^3$$ Using the quartic equation solver [here](https://keisan.casio.com/exec/system/1181809416) and throwing out the negative solution, this gives an answer of $r = 0.95$ meters for the radius at which you'll feel 1 g acceleration from the 133 million metric ton black hole. Any closer than that and the proper acceleration will be greater than 1 g, any further and it'll be less. On the other hand, if you pick a black hole with a mass of 8 billion metric tons = 8 trillion kg, the left side of the equation will be equal to 2968 meters^4, and the Schwarzschild radius in this case was found earlier to be $1.19 \* 10^{-14}$ meters giving the equation $$2968 = r^4 - (1.19 \* 10^{-14}) r^3$$ And in this case, this gives an answer of $r = 7.38$ meters for the radius at which you'll feel a 1 g acceleration from the 8 billion metric ton black hole. I checked these numbers against what would be predicted by the Newtonian formula where acceleration a at radius r from a point mass m is given by $a = G m / r^2$, and ended up getting the same answers for both black holes, given the number of significant digits I used (if I calculated the answer in both general relativity and Newtonian gravity out to more significant digits there'd of course be some differences eventually). And this makes sense since the general relativity formula $a = (G m r^{-3/2}) (r - r\_s)^{-1/2}$ would reduce to $a = (G m r^{-3/2}) r^{-1/2} = G m / r^2$ in the limit as $r \gg r\_s$. So, when considering radii much larger than the Schwarzschild radius, the Newtonian formula for gravitational acceleration will work find as a close approximation. This also means that at distances much larger than the radius of the black hole, you can assume the gravitational pull drops off according to an inverse-square law, i.e. if you know the pull at a given distance than at twice the distance the pull will be 1/4 of that, at three times the distance the pull will be 1/9 of that, etc. ]
[Question] [ My society uses dragons for various tasks. Blacksmithing, mining, warfare, fishing, hunting, carriage pulling/plowing, carrying messages, etc. My dragons have four limbs (2 legs/2 wings), and can get quite large. How might my society hypothetically "De-claw" dragons, especially more aggressive/wild-caught dragons who are not being used for warfare? Potential areas of danger (besides the obvious size) are a scythe-like blade on the end of the tail, the teeth, the fire, the claws, and the horns, which kind of make a spiky, potentially deadly frill. Both permanent (for uses other than warfare) and temporary (for warfare and potentially hunting/fishing) are great. Edit: Horns and claws grow continuously throughout the dragon's lifetime Edit #2: People don't have any real opposition to cruelty as long as it won't inhibit the performing of the dragon's task, i.e docking/amputating the tail above the blade if the dragon works in a forge. [Answer] 1) Claws and horns and spikes: specialized blacksmiths, just like with horseshoes. Semi-permanent: sawed, clipped, chiseled down. It would be a standalone profession, as it would be easy to agitate a "wild", not well-trained dragon. I imagine they wouldn't enjoy it and even protest against it, especially if the person doing it is unskilled and hurts them in the process. Temporary: Leather, cloth "gloves", covers they tie around the sharp parts to lessen them from cutting weapons to bludgeoning one. Restrictive chains, but that depends on dragon strength and metal quality. 2) Fire-breathing: Dog-style dragon muzzle. Even if they are immune to their own fires, I imagine it would be quite uncomfortable. --- You can look up a lots of house-pet, animal keeping solutions for your dragons. Zoos and exotic pet owners will have to deal with similar problems and you may found even better solutions than those I just mentioned. Especially in a society heavily reliant on dragon domestication, they will be advanced animal keepers with modern or even futuristic (dragon-specific) solutions (depending on their level and "setting"). Like, How to train your dragon, etc. --- To the Edit: Just because cruelty is not an issue, it doesn't make it efficient. Amputation and long-term "docking" may cause sever health issues in time. A low-morale, unhealthy dragon may not be a productive, well-performing dragon. The only reason livestock are kept cruelly is because of the easily accessible and cheap antibiotics preventing serious illnesses and plagues. Even that has a slowly eroding and far reaching negative effect on the global scale and may [doom all of humanity](https://www.youtube.com/watch?v=xZbcwi7SfZE). So yeah, there are always trade-off and always a price to pay for cutting corners in pursuit of profit. [Answer] This partially depends on a variety of things, but just think of livestock. A common way to make Bulls, Dogs, Cats, and other animals including Humans docile is by castrating the males. It's efficacy is questionable on the whole, but it's a method that has been in use for thousands of years. Remove the sex drive, and you remove at least one reason why these animals get aggressive in the first place. Spay the females and then they won't release pheromones when in season, which typically drives male animals into irrational frenzies. Just look at Deer in rutting season. Those are some truly dumb animals when a female is around. It's the same with house cats. Docking the tail is of limited value depending on what the animal is used for. Does the Blade like part help at all with flying? You'd have to leave it for messengers, hunters and war animals. Horns, spikes and claws. Either blunt or cover them. Covering them may not work too well, so drug the animal and break out an angle grinder and go to town. As for the flames, well, you are going to have a society with lots of metals, ceramics, and stone in your construction. Not a lot of wood. Lots of leather garb. At least until your society figures out Asbestos and Nomex. And you can do what many fairly brutal societies did when handling dangerous animals. Send the poor, stupid, or otherwise undesirable people to go in to take care of the Dragons and don't worry too much about safety. Just expect some "spoilage". If Bob the peasant gets roasted, well, just replace him with Bill the peasant. Peasants can always make more peasants. [Answer] Working with dragons is a lot like working with Elephants, anything you do to make them safer is going to be a moot point in the end when dealing with a creature that large. The best way to make animals that large safe is to breed them to be more docile. On top of that, dragon trainers would have be very good at maintaining a healthy relationship with the dragon and be able to recognize when it's time to stop working and give the animal a break, or intervene with positive stimuli before the animal becomes aggressive. [Answer] For horns, either saw them off, file them down, or use 'disbudding' which is what cattle farmers often do to young steers - put them in a kind of mechanical crush to immobilise them while the horn buds (the place on the skull where the horns are just starting to grow in) are cropped off with hot pliers or a knife and the wound is cauterised. The younger this is done, the better, though it can be performed on adults as well. This would likely be very painful for the dragon so heavy duty restraints would be required. [See this wikipedia entry.](https://en.wikipedia.org/wiki/Livestock_dehorning#Procedure) For the claws, either they could be filed down or removed in the same way cats are declawed, by amputating the end of the finger diget to prevent the claw from ever regrowing. You can also fit soft caps on the ends of the claws (which people do with cats as well) to make them scratch-proof as a temporary solution. Teeth can be filed down or removed. It used to be common to smash out the teeth of dancing bears and photographers' animals such as chimps and tigers to make them 'safe'. Sadly this still goes on, but if your society doesn't care about cruelty that would probably be a good option for the dragons too. For the fire, maybe you could have some sort of 'de-flaming' surgical procedure to remove the fire glands or ignition system or however dragons produce fire in your world. Or some kind of flame retardant muzzle. [Answer] I expect in much the same ways that it's done to large, dangerous animals today. If these animals can be caught, they can be subdued ... either with sedatives, magic or the like. Tails can be amputated (this doesn't necessarily kill terrestrial reptiles). [Answer] You can amputate claws and horns in newborn dragons or as soon as they start growing them. Another thing that comes to mind is possibly some sort of binding. Bones are never fully formed after birth and positioning parts of body in a certain way can create permanent modifications. (foot binding is one example) Although I'd argue those exist for a reason and could even be useful to humans if they train dragons to use them properly. Domesticating seems like a better option. Animals that grew up with humans or have been domesticated for generations become too docile and dependent on humans to be dangerous. Selective breeding can make species that physically lack dangerous parts too. Cattle is good real life example for both of these. ]
[Question] [ I, the Grand Sorcerer Alazam of the Guild of Arcanists, have invented a remarkable new spell! Using unique magical artifacts, I can create what I call 'living ice' - chunks of ice that grow and consume heat and magic as if they were alive. Other, lesser cryomages can summon static ice to form barriers or spikes, but my ice is superior! My ice acts as plant life or fungus does - it will consistently absorb the heat from the room in order to grow. The cold will spread outwards, and the lump of ice will consistently grow in size. This growth is very slow, however - at a rate of a few centimeters in an hour, and less in warmer environments. Very high temperatures such as fire will melt and 'kill' the ice permanently. When the ice is entirely melted, it becomes inert water, yet large masses are difficult to melt as it absorbs heat. Overall, the living ice behaves like a fungus which sucks up heat. It is not intelligent or sentient in any way. The growth happens in all directions equally, and any chunks taken from the mass will grow in the same way. Otherwise, this ice looks and has the same properties as the regular sort. I am, I admit, slightly concerned about the possibility of living ice being left unsupervised, and eventually growing to an unstoppable size... So then, remarkable though my power may be, I am unsure how to best apply it. What could be the best application for such a spell? --- TLDR: There is a constantly expanding, freezing cold, ice-fungus which can only be stopped by fire. What can be usefully done with it? [Answer] You can sell it. People in warmer climates like having ice to cool food for preservation. Rather than having to haul it great distances they can just put this in a cool shaded place and chip off pieces once in a while. Or put it in the lake your enemies use and watch them struggle with it while you laugh. Or put it in a river to block if from being sailed on. [Answer] In a couple of weeks you can create pathways over rivers and other bodies of water, or you can block boats from going up and down a river. This is useful in combat situations, when you have time to allow your plans to unfold. You can also put some into trenches with soldiers waiting for war. Whether they are compromised by the cold, or by the fire they're forced to set, you will flush them out. Again, it will take some time, but that's not always a problem. You'll need to find a way to apply the "fungus" to something that can't just be shoveled out to a safe spot and set on fire (or something that isn't noticed until it's too late). In the civilian world, use this for firefighting! As long as you get the amounts right, it should balance out properly so there isn't too little (the fire continues to rage) or too much (fire's gone but you've got a bigger problem on your hands). Ideally it would reduce the fire enough that ordinary methods are now manageable. Remember, it can take weeks to contain a large fire. It could be used to prevent or slow [meltdowns in nuclear power plants](https://en.wikipedia.org/wiki/Nuclear_meltdown). The time scale may be too quick here but it's possible it could help enough to take the edge off. If in place and ready to apply at the beginning of a core meltdown. Honestly though, the chance that the ice will get out of control over time is a very large risk. Either there needs to be a failsafe for it (can you, the Grand Sorcerer Alazam of the Guild of Arcanists, reverse it if you're on site?) or it needs to be used very very rarely and only for a few days at most. [Answer] The Ice as proposed would be a liability anywhere except areas in which the ambient temperature outside is enough to force the ice back. In desert-like climates, you could put it in a designated shady area just cool enough to allow it to grow but if it ventured outside it would melt. Larger scale applications could create oasis's? oasi? oaset? oasises? Anyways, with a large quantity of sun shielded ice you could create pools of water in the desert to shelter life. Basically, this is incredibly useful in the exact climates in which it cannot rampantly spread. [Answer] None! You are an artist! Applications? Practicality? How droll! Please - leave the pennies and profits to the wart-removing witches and traveling conjurers. And let those aesthetes who are prepared understand your works for the marvels that they are! You are an artist; a créatif whose medium is magic. You cannot be bothered with mundanities like how many potatoes it can peel. [Answer] Air conditioning. However, the growth severely complicates domestic/industrial use - about a meter per day, as proposed, is too much. It would be better to invent slow-growing (or not growing at all) ice that still absorbs heat. Or some other better way to control it than fire, such as dependence on rare/magic nutrients. ]
[Question] [ In a setting with multiple sapient fantasy races (ie, elves, orcs, humans, dwarves), assuming these races could interbreed and this activity became common, would they eventually reach a point of hybridization where there is really only one race that traces its ancestry to the all of the others? If so, would that race resemble a potential common ancestor of its predecessors, or would it be something entirely new? [Answer] Not completely. Humans are fully interfertile, and apparently were so with other human species (genus homo) in past history. Yet, despite hundreds of millennia of interbreeding, we have never become homogeneous. We all (as modern homo sapiens) carry genes from Neanderthal, Denisovan, the recently discovered fourth species, and possibly from Floresiensis and the newly discovered species from the Philippines. We've been interbreeding on at least three continents between different "races" for as long as there have been modern humans (quite possibly longer) -- and yet we still have at least three major races and a bunch of offshoots. I read a study once (in Scientific American, decades ago, so no link or exact reference here) that had found that all that's required for neighborhood segregation to continue is a pretty small preference for having neighbors like yourself. Add to that the known biological phenomenon of genetic attraction (the attraction for those genetically most similar to oneself, offset only by the effect of being raised together as family), and it's no big surprise that even after tens of thousands of years with only one human species on Earth and routine trade and travel (far predating latecomers like Marco Polo), there are still at least three major races. Given this, it seems unlikely that multiple actual species would become homogeneous, even over short geological time. There might well be a true-breeding race of "half-elves" who started as hybrids, but there will still be both elves and humans. And orcs, and dwarves, and whatever else. The tendency, in fact due to the combination of biology and psychology, absent a strong selection factor, will be for the number of recognized "races" to increase over time, rather than decrease. [Answer] It depends. If there are reasons for races to separate then it is likely they will remain separated 1. Physical - for example Dwarves being adapted to underground living, elves to forest living etc) . 2. Social - if the races are xenophobic or at war with each other then interbreeding is less likely. 3. Geographical - if the races are spread out over a large enough area that not much mixing happens you would see some "blurring" at the boundaries but no grand homogenization. On the other hand if the factors above are neutralized then you would expect a hybridization process to take place. If they had no physical reason to live apart, if the different species got on well and had no taboos against interbreeding, and if they all shared a small enough range then eventually you would end up with one species. [Answer] Given enough time almost certainly yes, but you're talking about many many generations. What comes out of the process may resemble an ancestor or be something completely new depending on a couple of factors: * Unique mutation fixation, if the distinct races have mutations that their shared ancestor never did and one or more of those mutations become "[fixed](https://en.wikipedia.org/wiki/Fixation_(population_genetics))" in the hybrid population then the result may not resemble anything that came before. * [Founder effect](https://en.wikipedia.org/wiki/Founder_effect), the make up of the first few generations of hybrids is going to have a disproportionate effect on the outcome compared to the races that come late to the interbreeding party. For example if Dwarves and Humans have been interbreeding for generations forming a genetically stable subspecies that can breed true within its own numbers and a few refugee Orcs and Elves are added to the mix only when both species have almost been wiped out the resulting race will technically be a four species hybrid but most of its genetics are human/dwarf with very little owing to its few Orc and Elf contributors. * Dominate genetics, it may be that a certain race, or races, has genotypes that are dominant in compared to similar genes in other races so for example orcish tusks may be a dominant dental formation complex leading to all hybrids being tusked, or elven hair genes may be dominant making all hybrid children blonde. * Underlying genetic differences, lack of, Tolkien's Elves and Orcs are, genetically, one species, but a lot of malevolent magic has been pumped in to twisting Elves into Orcs, how this magic factors in to any off-spring has the potential to change outcomes radically. * Transcendent traits, some traits that each race has may be due to non-genetic factors which may or may not fade as the generations mount up. [Answer] In the real world, if two creatures can interbreed, then they share a fairly recent ancestor, in evolutionary terms. There's essentially no way of getting around common ancestry in the real world, though. However, in a fantasy world, where entirely separate kinds of life can exist, interbreed, and be brought about by magic, none of these rules might hold. If some gods or mages wave their respective staves, rods and wands, in a non-euphemistic sense, and magically cause to spring into being from whole cloth the Elves and the Sentient Trees, and they can interbreed, then the whole thing goes out the window. In that case, the question requires us to make some assumptions: * There are two purebred populations A and B * They begin to interbreed at some rate, producing AB hybrids. * If an AB successfully breeds, the result will be another AB. * Neither side dies out for the duration of our experiment. * The two populations already have a single common ancestor. * We have infinite time. * Both populations are of finite size, and cannot grow to infinite size. Given these assumptions, the answer, I think, is a very firm "if the rate of population increase is slower than the rate of interbreeding, then eventually yes, otherwise maybe". It simplifies things to consider only half the problem: does population A ever come to all be descended from B? Consider the first interbreeding A+B pair. An AB hybrid is introduced into the A population. If the population ever reaches a point where nobody is a descendant of that AB, their lineage dies out, so we consider the next breeding pair. If the population ever reaches a point where everybody is a descendent of that pairing, then the answer is "yes". Those are the only two outcomes. At this point it should be obvious that there's no "no, they don't" outcome, there's only a "yes" and a "try again next time two purebreds interbreed". It might take forever, but they will eventually become all purebreds. So, the answer's "yes" so long as the number of AB members of the the A population that the As are willing to breed with, grows faster than the number of purebred As. The problem then becomes mathematical. When 100% of an AB's potential partners are likely to be As, the rate of growth of the ABs will likely be close to 100% per generation - they will all partner with As. 100% is a lot, but numerically, with only a single AB, this is the lowest-growth point for them. If the purebred A population grows by 2 in the same generation, then the proportion of ABs actually falls. If ABs reach 50% of the whole population, then 50% of male ABs will partner with female ABs, and 50% with female As (and vice versa for female). So their population will grow only by 50%, but this will be numerically huge: the population will go from 50% AB to 75% AB in a generation. When it reaches 99%, though... there are probably reasons those remaining 1% of purebred As remain purebred. Perhaps they are part of a culture which is extraordinarily insular and inbred. But over an evolutionary timescale, the inbred microsocieties will either die out, or interbreed. Even if they outlast the greater society, that just means (from our assumptions) that they instead will start to breed directly with the Bs. So it just becomes a matter of time. --- An illustrative exercise is a very simple Solitaire game: Setup: Split a deck of cards into a red deck and a black deck. Gameplay: 1) Replace the top card of the black deck one from the red deck: if the card taken off was a black card, place it in a discard pile. If it was red, place it back in the red deck. 2) Shuffle the black deck, and deal it out in 12 pairs: * If a pair is two of the same color, leave them unchanged. * If the pair is a red and a black, replace the black with a card from the red deck, placing the black card in a "discard pile". 3) Take your pile of dealt pairs, and repeat from 1). That's it! This version of the game represents the best possible case, where ABs (represented by the red cards) are always successful. Even this simple case will take some time to play, but it's clear that there's only one possible outcome: all the cards will eventually turn red. To get the reproductive success lower, play again but this time, replace as: * If a pair is two of the same color, leave them unchanged as before. * If the pair is a red and a black regular card, flip a coin: -- heads: replace the red with a card from the red deck, placing the black card on the discard pile. -- tails: replace the red with a black card from the discard deck, and place the red back in the red deck. This represents equal reproductive chance. But again, red will eventually win, as there is no "lose" state for red. Red will have generations where every coin flip comes up tails, and the red population will decline or even be wiped out. So the game will be a whole lot longer, but just mathematically, there is no outcome other than that all black cards are replaced by red. You can play AGAIN, this time rolling any number of dice, and only replacing the black with a red if they all come up with sixes. This represents a case where there's a HUGE reproductive disadvantage to the ABs. And yet, eventually, possibly some time after the heat death of the universe depending how many dice you choose to roll... the black deck must eventually turn all red. Because there is no other possible end-state to this game. What if you want to reduce the rate of interbreeding? Change step 1 to: 1) If you know the black deck holds only black cards, replace the top card of the black deck one from the red deck: place the removed card on the discard pile. This represents an interbreeding rare so low, that nobody interbreeds when there're any hybrids. (there might be many generations of interbreeding in between the death of the last hybrid, and the first interbreeding, but we skip over this). Even so, with that one "seed" red, either the whole deck will turn red (perhaps because you always roll only 6s whenever that one came up), or you will try again with another "seed" red. There's no other outcome. But you are playing with fixed population sizes. Now play the same game, but add infinite black cards to the discard pile and infinite red cards to the red pile. Every time you loop, add one black card to the black deck from the discard pile. Clearly, now you are far more likely to add a purebred black card into your deck than you are to roll sixes (or tails, or whatever your criteria are for reproductive success) for the red card. It's still possible for red to win. In fact, in our initial case, where we were assuming red was always reproductively successful, red will still win: gen 1 it will go from 1 to 2, gen 2 it will go from 2 to 4, and so on, not always doubling (since sometimes reds will form pairs), but always increasing by more than 1. But if you change "add one black card" to "add 50% of black cards" to represent a 50% population growth per generation, then it becomes impossible for red to win: even if we go for our "best case" above, there will always be more black added than red can hope to create on one generation. Remember that there are two groups here, A and B - we can cherrypick whichever of the two most rapidly becomes all-hybrid, --- TL;DR: Essentially, we're setting up an experiment with a population of As and ABs, where we guarantee that there is always a minimum level of ABs in the population by guaranteeing a minimum level of inbreeding with Bs. Unless we grow the population faster than the ABs grow, there's just no way you can not end up with all ABs, eventually. However, it might take a looong while, especially if social or biological effects make ABs less reproductively successful than As. [Answer] Blue eyes, brown eyes. Make the different races like dominant and recessive traits. Option 1: Your races (dwarf, elf, orc, human) as a whole are dominant/recessive. No matter how mixed up they are you will still have all of the races, though some may be more common and some more rare - about 75% dominant and 25% recessive. Option 2: Certain traits from each race are dominant/recessive. They can get all mixed up but they won't really homogenize. You might have orc-ish humans or dwarfy-elves, but the basic traits all stick around even if they don't all stay together. This way you can have certain areas were some race-traits are more common or more rare depending on who's been mixing with who. Option 3: Left handed people and color blind people represent a fixed percentage of the population. No matter who or where, about 10% of people are left handed. There's an evolutionary reason for this - left handed people have an advantage at winning sports vs right handed people (but rank about the same at everything else) and color blind people are better at seeing through camouflage (useful for hunting, but has obvious drawbacks). The genetic mechanics of this aren't well known yet as far as I know. You could tie races to something like this. Maybe 10% of people in human populations are always elves or orcs or whatever you like. [Answer] ## No Two reasons: ### 1 Preferential mating Many people prefer to marry within their group, whether it's religious, social, racial or any other subset of society. Whatever the origin and definition of the group it will slowly diverge. The separation is never 100% so there will always be mixed race people, but races as such will not disappear, unless you enforce mixing forever or start eliminating minorities. ### 2 Discrete traits Many racial traits, like skin colour, pointed ears or allergy to sunlight are defined by small number of genes. Because of the way genes work this means that if you have a mixed race family (A+B) their children will usually look like a melt of their parents races (AB), this makes intuitive sense. But, children of two mixed race parents can show any extreme racial features, two mixed race parents may have one child that looks almost like pure race A, and the second child that looks mixed like the parents. Bear in mind that inside they are all definitely still AB not a pure race, but by statistical fluke they may look like A. ### 3 Result Now because of the way society works (combine points 1 and 2) those pure looking mixed race kids are very likely to marry with the other people that look like them, maybe a pure A, maybe another mix like AC. Again, because of the way genes work, each of those mixed race kids that look like pure race A has about half of genes from race A, and half from another race (B, C, or D whichever was their other grandparent from). If you get a group of A-looking kids (AB, A, AC, AD, A, A) together in the next generation their kids will be almost pure A. The races will keep coming back. ### TL,DR The only way to homogenize a society is if the other races die out (naturally or otherwise) or are outbred by a large margin. Some of their genes will obviously remain, like we still carry some neanderthal genes, but neanderthals are gone. ]
[Question] [ In my world there is a rogue scientist who wants to wipe out at least 90% of humanity. He's has a sample of measles which are very contagious but he needs something new. Could he merge measles with Ebola or Rabies to create disease which is both airborne and very lethal? It's only one virus that can be possibly recombined with the others to achive the end to my story. Please for explanation of chimera- is it possible to do it ? [Answer] Rhinovirus. <https://www.the-scientist.com/features/catching-the-cold-39858> Mixing measles and Ebola kind of smells like coating a nuclear bomb with nerve gas. Too much! Better for your narrative is to mix it with something unexpected. For a story, I like the idea that a harmless pathogen should confer the ability to do great harm. Here is how it would work. 1. Rhinovirus has an arsenal of poorly understood tricks to evade the immune system, over and over. They are poorly understood because rhinovirus infections are generally so harmless. 2. When correctly merged with measles, the rhinovirus can slip the measles past the immune system in someone who has been vaccinated. 3. The deadly part is when the measles comes out. The immune system is faced with a sudden, overwhelming measles infection. The consequent overwhelming immune reaction leads to [measles encephalitis](https://www.encephalitis.info/measles-infection-and-encephalitis). Thus the fatality rate is near 100% in people with immunity to measles, either via vaccination or prior infection. Nonimmune persons get a regular case of measles. --- There are stray survivors, all of whom have low immunity for one reason or another: recent liver transplant, advanced HIV, extreme old age. But as a population, only the unvaccinated survive this scenario. Three-quarters of the way thru this story, a pissed off crew of Orthodox teenagers from Brooklyn show up at the villains lab and sort out his stuff. [Answer] Your logic is wrong In reality, the more deadly a virus is, the less deadly it is because people will actively protect against it. If a sudden new disease starts killing people, government groups like the CDC will enact quarantine and start working on a cure. People will avoid going out and wear masks and other protective clothing etc. Someone dies coughing up blood and the whole hospital will be shut down, every person who came into contact will be isolated and tested. If it escapes, people will isolate themselves in bunkers if needs be until the disease dies out or is cured. To wipe out most of the human population, the disease needs to be basically harmless thus doesn't warrant notice until it's too late. To do this you start with a cold virus and have it make people sterile. People will be over the disease and may not notice they can't have kids anymore until years later. This way the disease has years to spread and scientists may not even find out what caused the sterility in the first place. ]
[Question] [ Assume the entirety of Earth (all the land) is covered in a city. What would the climate be like in different parts of it? I.e., what would it be like on the coast, or inland? I imagine it would be unbearably hot inland because you have a planet-wide heat island effect plus hardly any wind. Interior parts of the city would also almost certainly suffer from near-perpetual drought in my mind. However, these are just my thoughts, and I am by no means an expert on climate nor the effects of urban development on local and global climate. [Answer] What you are describing is a giant urban heat island (UHI). I'm oversimplifying it here, but basically concrete and asphalt absorb more heat and release it slower than rural areas and this effect can be exaggerated where there are tall buildings and narrow streets as this traps the air and therefore the heat. The difference in temperature between urban and rural areas is usually greatest in the evening as the cooling process is slowed in urban areas. This warming effect isn't known to be exaggerated over time, i.e. cities don't continuously get warmer. City sizes can affect the evening cooling process, so the center of an area with tall buildings and narrow streets will cool after the outskirts of that area. But they won't necessarily reach a higher temperature in the first place just because they are the center of this urbanised area. So in general, your planet sized city is likely to be a few degrees warmer than it would be if left rural, especially at night. UHIs in hotter climates are known to effect rainfall, as clouds will rise over these warm air pockets leading to precipitation. So more rain around the coast of you giant UHI, this will especially be true the closer you get to the equator and areas where the prevalent wind comes from the ocean. Of course, with no rural land, that is a lot of water to drain away. Precipitation will still be affected by natural geography to a point though (e.g. how far above sea level an area is). [Answer] The thing which makes heat islanding *such* a big deal is partially that it's in pockets, contrasting with the cooler land forms around the hardscaped area, and that differential then drives local convection loops, trapping the heated air mass above the urban scape. The whole prospect changes absent the contrast; we need to know SO much more about the planet overall to posit reasonable responses: * land/sea ratios * topography (mountains, plains, valleys) * exposed geography / plantscapes in whatever un-urbanized areas there are (mountains - rocky or vegetated?) * whether there are extensive parks (Paris, London, Tokyo, Bejing, New York, Philadelphia, Denver, Boston) or disastrously few parks (Fresno, Jacksonville, Mesa) We also need to know how carefully this has been thought out and planned in process - there are some strategies which could make large scale urbanscaping far less climate-unfriendly: * greenrooves * pervious / impervious paving * grass pavers vs asphault * intentionally designed mico-climate generating ratios of heat islanding between differing sections and heights to intentionally generate currents, winds and pressure differentials * alignment of taller structures with prevailing winds to cool large masses / generate wind-power * power generating base: coal or oil-fired, nuclear fission or fusion, wind and tide turbines, massive solar on all rooves, antimatter/matter reactors, Schwartschild Discontiuity generators * widely used high efficacy mass transit - so no cars, nor significant commuting pollution Hopefully you get the idea. [Answer] As @KMo mantioned, the Heat Island Effect (HIE) won't really effect windfall or overall wind patterns. You will still get relatively normal winds. What will have a big effect on rainfall will be the height of the city. As wind is diverted upward, it's density/pressure decreases and it can't hold as much water. That water then precipitates as rain. If the mega city is similar to our own cities where most buildings are 1 to 10 levels tall, then there won't be much affect on anything. The leading edge of the city on the coast will act as low rolling hills and might slightly increase rainfall there. If the buildings are taller 100-200 levels then the edge effects become more pronounced and more rainfall will happen at the edge. If the buildings are 500+ levels, they start to have the effect of mountains and you will tend to get very little rain away from the coasts. I see 3 issues. The one relating to the above is water management. The water collected at the coast has to get transported toward the center. The second is the lack of O2 from the loss of plants. The third, relating to the second issue is massive starvation due to lack of food. [Answer] There is talk about how it would create a hot island effect but I find that whenever people envision a world city, they think in terms of our cities today - concrete, glass, and steel (mainly) and so it is understandable to end up at such a point. My thought has always been that a city in general, but especially if the city were to sprawl across the entirety of the world I think that the world would need to adjust accordingly. One thing is what about new building materials, which would likely be developed by the time a world could advance to the point of covering the planet. I don't think that the materials that would be used would be the sort of materials of current time. The next thing is that the rooftops of buildings are a great place for greenery. You can easily put grass, trees, and flowers on top of the buildings. From a satelite, it would look as if the planet was completely green. It wouldn't be until you got closer that you would see the city underneath. From there, you can still cover the sides of structures with greenery as well. These are things already in place around the world and so I imagine a world-city would likely go this route. I am sure that this would still have a major impact on the climate, but I think that this would minimize any hot island effect and would make the place more pleasant to view and live in. [Answer] Well it all depends on how your city is constructed. If most of your buildings are one or two storeys then lack of wind is hardly going to be an issue (as opposed to if every building was 20 storeys tall. Additionally, it depends on how many green spaces you have in the city. For example, New York City is not just one big slab of concrete with buildings on it, you have central park, a large green space in the middle of the city. In this global city, you could have a lot of these green spaces and still claim the world is covered by a city. Something to consider, you would still need crop farms, tree farms and orchards in your planet-wide city, otherwise you will not have any any food or wood. Even if these are built in the city, they still need to exist, reducing the heating effect. Finally, consider the original temperature of the planet, if most of it originally was a frozen wasteland, having this mega city could instead make it a comfortable temperature. ]
[Question] [ In various TV series and movies villains or organisations have been shown to control animals through technological or cybernetic means, such as the future predators in Primeval. These creatures have technological implants that allow them to be controlled remotely by one individual from a tablet. Theoretically, how could this technology work? Requirements: * Allow complete control of the organisms motor functions, it doesn't have to affect natural bodily functions (heart rate, blood pressure, etc.) * Be able to be controlled remotely, possible through radio waves or some other means * Must be able to work or interface with a wide variety of creatures including animals like higher mammals, reptiles, fish, insects and other creatures (not including humans) [![Controlled Future Predators](https://i.stack.imgur.com/WhB39.png)](https://i.stack.imgur.com/WhB39.png) [Answer] [We already have working remote control for bugs](https://www.bugs.com/blog/remote-control-cockroaches/) and all creatures with a spine would simply need an implant at the spine. Somehow you would have to know which impulses to give to which nerve and with that your remote control would already work. Thats everything you wanted to know right? [Answer] If I remember correctly, we already have the necessary technology. The problem is the fine tuning. You need a variety of animals of the same species to experiment on. Then you build a little computer chip right at the nerves that control muscle groups, preferably in the brainstem or even better the motor cortex, as you'd only need one implant. Next step would be to let the animals live and move, while the implants log all neural stimuli. These have to be compared to the actual movements of the animals. When you have the data, the implants can be used to give stimuli and cancel natural ones. I don't know if this would actually work with insects and mollusks as they have a different nerve system. You would need at least four implants on a single cockroach. You need one for every brain or ganglion. It works by sticking really little electrodes into the axons or brain/ganglion areas and feeding it electrodes. And thus it would look like a microchip with done kind of battery and little metallic stings all around. ]
[Question] [ Could one make a smaller eclipse kept stationary on the surface of the earth in order that one may be able to see the stars 24/7 from one site? How could this be achieved? Geostationary satellite with a heap of fuel to steer it keeping the shadow path on the one point? [Answer] A geostationary satellite can only be placed above the equator, and therefore could create an eclipse only on and around the equator (assuming it has the right size). Not very useful to observe circumpolar stars, together with the major complication that the atmosphere around the equator is usually really humid and therefore lowers the quality of the observations. To generate an eclipse the satellite should have at least the same angular size of the Sun, which is about 0.5 degree. The relation between dimension, distance and angular size are expressed according to the formula $\alpha=2 \cdot arctg$$D \over L$. [![enter image description here](https://i.stack.imgur.com/fLvI1.png)](https://i.stack.imgur.com/fLvI1.png) Considering that the geostationary orbit is at 35786 km above the surface of Earth, this gives us a transverse dimension for the satellite of at least 333 km. A structure of that size could be built with something similar to a solar sail, a thin and opaque foil kept in position by a frame, and it would be a challenge to balance it against the pressure of the solar wind and solar light. Not even mentioning the need to repair it against any hole created by micrometeorites. Last but not least, the Sun is not at the same azimuth around the year. I am not a pro in orbital mechanics, but I am pretty sure that there is no way to keep a satellite geostationary while chasing the Sun along its walk across the ecliptic around the year. Summarizing, a geostationary satellite would not be feasible: too large for our current technology level and not able to chase the Sun year round. To quote what AlexP stated in a comment to the question: > > A stationary eclipse requires an object which sits always on the line between the Sun and Earth. Such an object revolves around the Earth with a period of one year. The radius of an Earth orbit with a period of one year is exactly the same as the radius of the orbit of the Earth; the problem is that there already is another object there, namely, the Sun > > > [Answer] A much cheaper way to create an eclipse like effect is a coronagraph. > > A coronagraph is a telescopic attachment designed to block out the direct light from a star so that nearby objects – which otherwise would be hidden in the star's bright glare – can be resolved. Most coronagraphs are intended to view the corona of the Sun, but a new class of conceptually similar instruments (called stellar coronagraphs to distinguish them from solar coronagraphs) are being used to find extrasolar planets and circumstellar disks around nearby stars. > > > The coronagraph was introduced in 1931 by the French astronomer Bernard Lyot; > > > <https://en.wikipedia.org/wiki/Coronagraph>[1](https://en.wikipedia.org/wiki/Coronagraph) Coronagraphs are used in both observatories on Earth and space observatories such as the Hubble Space telescope. Of course coronagrphs only work for observations through the telescope they are attached to and thus do not make it possible to see ordinary stars with the naked eye during daytime. However, the brighter stars can be seen in telescopes during daylight if aimed at the calculated position. And daytime air is usually more turbulent than night air making observations less useful. As far as I know, nobody has yet invented a method of making the stars visible during daytime for people using the naked eye. [Answer] You can put your umbrella in the Lagrange point between earth and sun (there are a few satellites positioned there observing the sun), trouble is L1 is 1.5 million kilometers away, so your umbrella needs to be tremendously (5 times our moon) large, and you need to move it forth and back by ~12000 km per day. (Side note: your town has to be somewhat close to the equator, because otherwise you need constant additional propulsion to keep the shadow from moving towards the equator.) In short: Impossible. (Also you wouldn't be making friends with your neighbours, because a terribly large area around your town, much larger than with an ordinary solar eclipse, would not see much of the sun either. The way weather works, everybody in the vincinity will get a severe temperature depression from not getting much sun plus a constant downstream of cold and dry air from the upper atmosphere. Freakin' cold, no snow.) [Answer] If you have steady enough wind, you might just build an oversized airplane and let if hover over your town. It's huge, lightweight, and flying very slowly, so it won't need much energy. You could probably power it with photovoltaics. Much friendlier than my other proposal above. Of course you need to ground it overnight. Where do you land with a plane that is several kilometers large? ]
[Question] [ This question already has answers here: [Other blood colors](/questions/28276/other-blood-colors) (6 answers) Closed 5 years ago. I've been working really hard for a while now on a race of creatures called Nordic mountain Valkyrie Dragons. They are large: around 7'ft tall, and 9'ft from nose to tail tip, and I'm trying to come up with a kind of blood that they might have. I don't want to use red, iron-based blood, as it wont really fit with the backstory I've given them, but I also want to have the blood be based on a metal that would actually function. They live in a cold and mountainous area, so whatever kind of blood it is, it needs to be efficient in keeping them warm to whatever reach it can. On top of this, it needs to be able to function with relatively low oxygen levels, as they tend to live at very high altitudes. I am NOT just looking for color. I have searched everywhere and found nothing, so I would really appreciate some help. [Answer] Icefish style: clear blood. The icefish has no hemoglobin or other oxygen carrying pigment. Oxygen dissolves directly in the blood. <https://www.popsci.com/science/article/2013-04/weird-fish-has-clear-blood> > > The ocellated icefish, for example, has clear blood. It's not very > well understood how or why this is. The red color of most blood is > given by hemoglobin, a protein that carries oxygen along through the > bloodstream to the organs that need it. > > > The ocellated icefish ("ocellated" refers to the eye-like spots that > make up the fish's coloration) does not have any hemoglobin. Its > circulatory system gets along without it: oxygen, rather than being > transported by the hemoglobin, is fully dissolved in the plasma (the > main liquid element of blood). At those cold temperatures, oxygen > dissolves into plasma more easily, and the muscles of the fish's > circulatory system are able to absorb oxygen directly from the plasma. > > > That's all helped along by the fact that the ocellated icefish has an > extremely strong circulatory system. It's got a much larger and > stronger heart than most other fish, and pumps blood through its body > at a rate five times greater than the average fish. > > > Clear blood dragons need it cold and they need to stay cold; the colder the better. The warmer it is, the less oxygen dissolves in plasma and the less they can deliver to muscles and organs. Maybe you can rig some way in which they can dump excess heat into their breath weapon, leaving their bodies colder? Also, the icefish is kind of sluggish. Your dragons could accumulate an oxygen store in myoglobin - that does not circulate but is part of the muscles. Oxygen stored in myoglobin is how whales can pull off their deep dives. That oxygen storage would enable a one time burst of activity on the part of the dragon. [Answer] # Scandium 1. It's rare and there isn't really any data to indicate that it wouldn't work. 2. It oxidizes faster than iron, so it is ideal for lower oxygen levels. 3. It's yellow when oxidized, and white or silvery when not oxidized. 4. It is generally considered to be non-toxic PS. The metal that carries the oxygen around in the blood doesn't constitute a large enough fraction of the blood to have an effect on how well the fluid transfers heat. At the end of the day, all blood is mostly water, which is good at carrying heat. As far as keeping them warm, it's more about insulation and good circulation than anything else. [Answer] Look to nature Well, hemoglobin is iron based, but [hemocyanin](https://en.wikipedia.org/wiki/Hemocyanin) is copper based and is used by many animals. The [Ocellated Ice Fish](https://en.wikipedia.org/wiki/Chionodraco_rastrospinosus) does not use metal hemoglobin or hemocyanin It depends upon the oxygen that simply dissolves in the blood plasma. I suppose Cobalt and Nickel are also likely metals that bridge the gap between Iron and Copper and perhaps could be reasonable substitutes. Heavier elements are less viable due to relative scarcity if nothing else. ]
[Question] [ How would lower gravity, let’s say around ½ of Earth’s, change the efficacy of different Bronze Age projectile weapons? How would the effective range, accuracy, and penetrating power of bows, javelins, atlatls, and slings be influenced? Does lower gravity favor any of these systems over the others? How might these weapons be modified from their Earth counterparts to be more effective in a lower gravity? For example, would projectiles be made more massive? [Answer] As @theRiley points out in comment, also note that the reduced gravity will likely mean your people have reduced muscles and therefore reduced strength. Because of this, projectiles which rely on the strength of the shooter, such as thrown rocks and spears, will not have the same range and momentum as they would if thrown by someone visiting there from Earth. --- All other things being equal, the main effect of the gravity will be that the object does not fall back to the ground as soon and will instead have a higher range and possibly improved accuracy. All gravity does is pull things toward the ground. In fact, if we ignore objects with different aerodynamic profiles for a moment, we can say that all objects fall to the ground at the same rate. It is a common sight in introductory physics to see people get all riled up when you tell them that a bullet shot out of a gun parallel to the ground will hit the ground at the same time as an object released at the exact same moment to fall to the ground. A projectile will travel in an arc along a parabola. The higher the gravity, the greater the change of direction in the curve. So to project farther, you have to aim higher. This much is intuitive: if aiming a bow or a gun at a distant object, you actually have to aim above the object. In lower gravity, you would not have to aim quite as high. Your shot would be straighter for a target at the same distance, so the accuracy would be improved. If going for distance, since the object does not fall to the ground as fast, it will keep moving away from you and will have a farther range. All other things being equal, nothing should change significantly concerning penetrating power, at least not that I can think of. More massive? Obviously yes. Since gravity is reduced, you can more easily project a greater mass. I could pick up a larger javelin to hurl. However, though I can pick up and throw a larger mass, the larger mass will still have a larger resistance to change in momentum. I can throw a larger rock or javelin, but since its speed will be lower we will not have a linear increase in momentum with larger objects (ie: just because the rock is twice as massive doesn't mean it will hit twice as hard, since I cannot throw it as fast as a lighter variant). We see this same effect in modern guns. Some handgun owners think that their .45 caliber handgun is so powerful because shoots such big bullets. But it takes more energy to get those bigger bullets up to speed, so often the .45 caliber handgun bullets are being shot at slower speeds than smaller bullets. For some ammo, the total momentum (and thus the total impact force) of a .45 is only slightly higher than a smaller round like a 9mm. Same thing with your more massive ammo: you can hurl larger shots and they will go further, but at a certain mass there will come a point when you are not increasing the actual momentum and therefore not increasing the impact force hitting your target. At what point these diminishing returns get in the way I'm not sure, but I doubt the size and mass of projectiles would increase by a lot. Probably no 1-foot-diameter sling stones for example. Range: increased. Accuracy (given the same distance as a full-G target): increased. Ability to project higher mass: increased. Impact force from higher mass: increased but only marginally, with diminishing returns, just like we have on Earth. [Answer] The range of a projectile launched with initial velocity $v\_0$ at an angle $\alpha$ is given by $r=$$v^2\_0 sin(2\alpha) \over g $. We see immediately that changing $g$ affect the range. In your case, the range would be doubled at any angle. The damage delivered by the projectile is dependent from its initial kinetic energy, which is $K=1/2mv\_0^2$. Here we see that gravity doesn't play a role. Summarizing, by lowering gravity and keeping all other factors, such as projectile mass and initial velocity, the same, you only increase the range of the weapon. The rest will remain unchanged. If you want to increase the damage, you have to increase the mass of the projectile and, since the energy that the launcher can transfer to it is fixed, accept a proportional reduction in range. In the formula above drag is neglected, but the final deduction still holds. ]
[Question] [ In relation to [a recent question of mine](https://worldbuilding.stackexchange.com/questions/123948/if-earths-core-had-all-of-the-heavy-metals), this alternate Earth still has its core consisting of 84% iron, but the other 16% contains the greatest concentrations of all known species of heavy metals (defined by high atomic number and weight and a specific gravity greater than 5), including 100% of all 34 species of metals so unstable that they are radioactive, like plutonium, uranium and strontium. There would be many questions to this scenario, but let's narrow it down to one focus--Earth's mantle. The mantle is where we find the action of convection, the reason why Earth's outer shell moves in several pieces, or plates. [![enter image description here](https://i.stack.imgur.com/aFBbU.gif)](https://i.stack.imgur.com/aFBbU.gif) In an alternate Earth where all of the radioactive metals are trapped inside the core, would this affect the process of convection in any way? If yes, how? [Answer] # The radioactive metals would not be in the core The primary heavy radioactive metals are not chemically reactive with iron, but they are with oxygen. Therefore, most of them would form compounds that are not as heavy as the heavy metals in your definition. Most of the heat you will get from the core would be from four metals ([see this post on ES.SE for further details](https://earthscience.stackexchange.com/a/4802/6703)): * Uranium 235, with a half-life of 0.703 billion years, * Potassium 40, with a half-life of 1.277 billion years, * Uranium 238, with a half-life of 4.468 billion years, and * Thorium 232, with a half-life of 14.056 billion years. These metals will form compounds that are no longer as dense as heavy metals, thus falling into the 'rock' category of [Gimelist's answer to your last question](https://worldbuilding.stackexchange.com/a/123951/23519). A repeated melt cycle as proposed in your question will in fact increase the concentration of radioactive minerals in the crust and decrease them in the core. So relative to our Earth, your planet will have less radioactive heat in the core. Thus there will be less temperature differential across the mantle, and less convection. What effects this has on geomagnetism and plate tectonics are hard to determine, but they don't sound good for life on the planet. [Answer] kingledion's answer is spot-on: the metals will not partition into the core. The only way to put radioactive metals (i.e. U, Th, and K) in the core, is to lower the [oxygen fugacity](https://en.wikipedia.org/wiki/Mineral_redox_buffer) of the planet as a whole. In layperson's terms: get rid of the oxygen. It is well known that alkali metals (including the radioactive potassium), thorium and uranium will partition more to an iron and/sulfide rich liquid if there is a shortage of oxygen around. For example: [Experimental partitioning of uranium between liquid iron sulfide and liquid silicate: Implications for radioactivity in the Earth’s core](https://doi.org/10.1016/j.gca.2005.11.023) [Depletion of potassium and sodium in mantles of Mars, Moon and Vesta by core formation](https://doi.org/10.1038/s41598-018-25505-6) Here's an SEM image from one of my own oxygen-starved experiments, where you can see tiny iron "blobs" inside silicate melt (call it "rock"). This iron concentrates sodium, which is an analogue for potassium. [![enter image description here](https://i.stack.imgur.com/DX4fb.jpg)](https://i.stack.imgur.com/DX4fb.jpg) So in theory it is possible, but the lack of oxygen will cause two things to happen: 1. Your core is going to be larger, because more iron will remain as "metal" and not be oxidised to "rock", 2. You will not have free oxygen in your planet. This will have major consequences for the possibility of advanced life forms as we know it. ]
[Question] [ My alien civilization is entering the space age, and have reached the point where they will be sending ships hundreds of light-years away. Instead of generation ships, my civilization is building bio-mechanical entities in their image, which will survive the long distance they need to travel to get to a habitable planet. The biological parts are sustained with exact chemical compounds provided specialized machines, put I was thinking of making one of their internal organs a miniature fusion reactor. It would need to be able to power a mechanical body and a very advanced computer brain, as well as being able to provide power for hundreds of years. Considering this civilization's advanced nuclear capabilities, this seems like the most viable option. Am I overlooking anything? Would a fusion reactor work inside an android? [Answer] For a human sized machine, making a fusion reactor using current technology would be very difficult to almost impossible (actually, with current technology there are no fusion reactors capable of operating at a net positive energy production). However, there is a hypothetical design for a fusion reactor which could meet these requirements: [Non-Statistical Fusion Reactions In Atomic Scale Accelerators](http://www.islandone.org/Foresight/Conferences/MNT05/Abstracts/Donoabst.html) The idea can be visualized by imagining a sheet of material with parallel grooves cut in the surface. Small ball bearings would roll down (or be shot down) the grooves from either end to collide in the centre. Now scale that down so the "ball bearings" are deuterium ions individually shot down the grooves to collide and undergo fusion reactions (with the tracks correspondingly small). [![enter image description here](https://i.stack.imgur.com/si4x1.jpg)](https://i.stack.imgur.com/si4x1.jpg) Do this at atomic scale Each track would only produce a tiny amount of energy, but scaled so there are thousands of parallel tracks, you could produce a reasonable amount of energy with a reactor the size of a computer's CPU. The associated machinery for thermal control, energy management etc would probably result in a reactor about the size of a notebook or laptop computer. Using D+D reactions still has the issue of radioactivity from neutron emission, and the device itself will likely be both extremely hot and extremely radioactive in use. Refining the process to use p+Be reactions for aneutronic fusion may be possible, but since the reaction is much more difficult to carry out, a D+D machine is likely the first generation possible. [Answer] [Current Fusion reactors](https://en.wikipedia.org/wiki/Fusion_power) are really difficult to operate, and generate so much radioactivity that the reactor walls degrade. Our own deep-space probes (Voyagers) use this [radioisotope thermoelectric generators](https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator). If you want your reactor to function for years (or centuries), you want to make it as simple as possible. On the other hand, maybe your aliens feed off radiation, and generate the pressures and temperatures necessary for fusion reaction within their bodies. Although this would be more plausible for creatures living on the surface of a star than a planet. :) [Answer] TL; DR: I have left the most interesting and exotic way of getting energy at the end and the most plausive at before the last. At the moment, scientific has already made some fusion reactors, the problem is that currently, they consume more energy to work than the produced by them, in addition, that they are very expensive and dangerous. In order to fuse atoms, you need a high pressure or temperature, and any of both things can't be made in such a tiny space as an organ. Maybe with future technology, it will be able to reach the necessary pressure or temperature but I would be something so difficult (for the tiny space) that wouldn't be able to fuse many atoms per second, not very useful. Furthermore, fusion use to produce high energy particles like gamma rays, which are not exactly healthy for living organism nor some technologies. You need something that doesn't need so extremes environments in order to be much smaller. ## [Cold Fussion Reactor](https://en.wikipedia.org/wiki/Cold_fusion) But you don't need to make exactly a fusion reactor, you could use other techniques like a [cold fusion](https://en.wikipedia.org/wiki/Cold_fusion) reactor to produce energy at room temperature. Sadly, cold fusion is quite close to sci-fi technology than the real one, so there aren't many ideas of how to do it. Luckily, there is something called [muon-catalyzed fusion](https://en.wikipedia.org/wiki/Muon-catalyzed_fusion): ## [Muon Catalyzed Fussion](https://en.wikipedia.org/wiki/Muon-catalyzed_fusion) The biggest problem to fuse atoms is the "electromagnetic force field" that they have. The electrons cloud doesn't let two atoms be very close because both clouds are negatively charged, repelling themselves. If you strip an atom from its electron cloud, it still has their positive charge from proton to repel them, but when atoms get enough close to be repelled by the electromagnetism, nuclear force gains priority and pulls from the gluons of both atoms in order to combine them. If we were able to find a much cheaper and easier way to find muons and "inject" them into atoms we would be able to make fusion at room temperature. That is because of muons which are a different kind of electrons, much heavier than normal ones (207 times more heaver). Because of their mass, they are much closer to the nuclei of an atom, so it's easier to get close two atoms enough in order to combine them using the strong force. We just need a way to replace normal electrons with muon versions. > > The muon, with a rest mass about 207 times greater than the rest mass of an electron, is able to drag the more massive triton and deuteron about 207 times closer together to each other [...] > > > [Here](https://en.wikipedia.org/wiki/Muon-catalyzed_fusion#Process) it's explained the process. # [Cold Fission Reactor](https://en.wikipedia.org/wiki/Cold_fission) Not actually a fusion reactor but it's the first time I've read about it so I wanted to mention. It's a special kind of fission reaction which doesn't high excited particles like neutrons or gamma rays, in order words, it's really safe (alpha particles are stopped by the skin, and beta particles by a thin layer of aluminium). # [Radioisotope Thermoelectric Generator](https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator) Also not actually a fusion reactor but still a worthy mention is the use of an RTG: > > A Radioisotope Thermoelectric Generator (RTG, RITEG) is an electrical generator that uses an array of thermocouples to convert the heat released by the decay of a suitable radioactive material into electricity by the Seebeck effect. This generator has no moving parts. > Emphasis mine > > > That is great, it use decaying sustances (like uranium) and produce a constant flow of energy without maintenance (just more fuel). It isn't explosive, it doesn't need much cooling, it's perfect! > > RTGs have been used as power sources in satellites, space probes, and unmanned remote facilities [...]. RTGs are usually the most desirable power source for unmaintained situations that need a few hundred watts (or less) of power for durations too long for fuel cells, batteries, or generators to provide economically, and in places where solar cells are not practical. Safe use of RTGs requires containment of the radioisotopes long after the productive life of the unit. > > > Literally, it turns the heat of the substance decay into electricity. # Betavoltaic device Basically, this device produces energy when it receives [beta radiation](https://en.wikipedia.org/wiki/Beta_particle). I'll transcribe a part of [my most upvoted answer](https://worldbuilding.stackexchange.com/a/97763/35041) (I always wanted to say that!): [Diamond batteries](https://en.wikipedia.org/wiki/Diamond_battery) are able to produce a low flow of constant energy for thousands of years. Sadly, over time the radioactive material start losing its power and the battery decrease it voltage over time (a bit similar to RTG). I'll quote two paragraph of [here](https://www.forbes.com/sites/jamesconca/2016/12/09/radioactive-diamond-batteries-making-good-use-of-nuclear-waste/#1511d885a044): > > These radioactive diamond batteries would have a very specific purpose – low power and extremely long life. A standard twenty-gram non-rechargeable AA battery stores about 13,000 Joules and will run out of power in about 24 hours of continuous operation. One diamond with one gram of carbon-14 would produce 15 Joules per day, much less than an AA battery. > But the power output of the diamond battery is continuous and doesn’t stop. The radioactive diamond battery would still be putting out 50% power after 5,730 years, which is one half-life of carbon-14 or about as long as human civilization has existed. During this time, the diamond battery would have produced over 20 million Joules. And would produce another 10 million during the next 5,730 years. > > > Also, you can see this [five minutes video](https://www.youtube.com/watch?v=b6ME88nMnYE). With enought technology, that could be very useful and luxurious! [Answer] There are some interesting responses here, but I feel I can shed more light on the radiation hazard for fusion reactions. In the ruins of Chernobyl, close to the corium, there is now an abundance of [radiotrophic](https://en.wikipedia.org/wiki/Radiotrophic_fungus) life. That is, fungi and lichens that feed entirely on ambient radiation. While the levels of radiation in that area would kill any one of us within a few hours, the melanin-containing fungi are now completely dependent on it. (In its absence, they starve to death.) So, radiation itself, given an evolution-level timeline, isn't necessarily going to kill off the organic part of your biomechanoid; given that you prepare for it on the organic end. Even humanity has a budget against radioactivity; in any given individual adult, anywhere around the world, you'll find an average of around 60 mg of uranium (not weapons grade, but still). We didn't put it there; it didn't start showing up with the atomic bomb or anything like that; it's just ambient; and yes, it is still dangerous; but our cells commit apoptosis on detection of the kind of mutations it can cause (usually) and the body expects to sacrifice a certain minimal number per unit time. That said, let's look at the radiation likely to be put out by a stable fusion reactor. It's worth noting that all stable fusion reactors in existence to date still only run for a number of milliseconds, as the disruptive (and potentially reactor-destroying) phenomenon of a "major disruption" from runaway electrons is a frequent occurrence. Thus, it doesn't make much sense to look at their radioactive output; and you're going to have to use some kind of handwavium here. Or, you know, find a way to commit stable energy production with a real-world fusion reactor; but whatever. Tokamaks aren't the only method of generating fusion that we know of, though; laser-induced fusion is always a possibility, and moreover, particularly for the size you're looking at, [bubble fusion](https://en.wikipedia.org/wiki/Bubble_fusion), also more accurately known as sonofusion. The history of sonofusion is rife with fraud and falsifications, but the core science to it is sound enough. The idea is that fusion can occur during the collapse of very large gas bubbles, which have been formed with acoustic waves. The potential is definitely there, though we're having the damnedest time finding verifiable evidence of it happening. Note that this is effectively the release of fusion energy from fizzing water; it doesn't reach an unmanageable temperature, though it does require some energy to induce it (and don't ask me how much energy, we're not even sure we've managed it yet, so I wouldn't know). I could see something organ-sized producing this. Tokamaks are larger than a barn, hazardous to local machinery, drain boatloads of power to induce the reaction, and are unlikely for any but the largest conceivable life forms. So, there you have it; you'll need a slow-burn fusion reactor that can be minimized in size, like a sonofusion reactor, and organic components that have adapted to its continual waste-energy output as radiation; then, maybe you could power your life form with fusion. ]

Subsets and Splits

No community queries yet

The top public SQL queries from the community will appear here once available.