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[Question] [ Essentially in my world I have a large and mountainous kingdom, but I have always envisioned them wearing leather armor with cloaks etc. Is there a valid reason I could state for why they don't wear metal armor? Because I feel like if the option is there, for the time period my world mimics, they would be wearing metal armor realistically. Is it possible to simply have mountains that don't have much metal in them? Or any other reasons why a kingdom doesn't wear metal armor. I know this is a fantasy world but I don't want to just say 'No there is just no metal in the mountains' if this isn't a realistic possibility. [Answer] I can think of two options. **Lack of extensive forests**, you need a lot of fuel to smelt iron, in medieval times that basically means wood (or charcoal made from wood) If they do not have much timber to spare they will not be smelting iron, but they can always sell the ore. **No ferrous metal ores**. Of course many mountain ranges are not particularly ore rich. So yes you are completely fine to say they do not have much in the way of metal deposits, or the deposits they do have are things like precious gems or metals useless for armor, like silver or tin. Valuable for trade but not strategic. **Not enough labor surplus**, As an example the norse had iron mines and produced limited amounts of metal armor in the form of chainmail and helmets, but the vast number of fighting men would not have had metal armor with the possible exception of an metal helmet. Only the wealthy could afford a chainmail. They did use iron weapons however. This was actually fairly common in societies without a standing army, metal armor is expensive. [Answer] Cost, as suggested, is definitely a means of preventing the use of metal armour, but if you absolutely, positively have to have a region or culture not do something that would otherwise make sense, you can't beat... **Religion** Assuming that it's not set in our own world, have the local religion forbid encasing the body in metal, which cuts the soul (inside the body) off from the deity/deities/nature (outside the body). Anyone disobeying the taboo faces social or political (depending on the standing of the church) censure. Et voila, you can have the kingdom export iron ore but not wear a scrap of metal armour. [Answer] While other answers deal with *availability* of metal armour, there is also another aspect to your question: *usability*. Carrying a dozen kilograms of metal may be only mildly annoying on a flat road, but carrying the same amount while alternately climbing and descending at a steep rate and in the thin air of few kilometres of elevation will either force you to severely limit your marching speed, or exhaust your to the point of being unable to fight. Simply put, warfare in mountains often favours smaller, faster units of lighter skirmishers, which makes heavy metal armour not as desirable. If your kingdom does not seek to expand into flatlands, and adopts hit-and-run tactics, it doesn't really make sense for them to use metal armour beyond protection of their leaders. Another reason for leather armour would lie in the (relative) abundance of leather. Most mountainous societies relied on hunting significantly more, than other countries, simply because there was less arable land (even with quite advanced alpine agriculture techniques some of them used, like Inca). And with hunting, you get not only meat, but leather as well. So, a kingdom of leather-clad hunters in the mountains is quite plausible. In fact, you can just take a look at the medieval kingdoms of Caucasus for an inspiration of just that. [Answer] # Iron doesn't come from the mountains Iron ore was most commonly found in ancient times in 'bog iron' which is deposited in current and former swamplands. Mountainous terrain, especially if it is dry, doesn't have to have many, or any, bogs. The biggest iron mines in the world don't really correspond to mountains at all. Of Kryvvy Rih and the Kursk Magnetic Anomoly in Russia/Ukraine, Mesabi Range in Minnesota, the Carahas mines in Para, Brazil, and Pilbara, Australia; none of these are in mountainous areas. There is no reason that your mountainous region has a lot of iron available. If the world is in an iron based timeframe (say, an Iron Age), then your land will be relatively metal poor. Even if it has the materials for making bronze, if there is little bronzecraft in the rest of the world, your land might not have the skills needed to make weapons or other everyday items from bronze. # About bronze... Copper deposits are generally found in the mountains; however, bronze needs both copper and tin. Tin is pretty rare, and can't just be found everywhere. There are plenty of areas of Earth with no nearby tin, mountainous or otherwise. If you want an additional reason for your people to not be using bronze, then lack of tin is it. Copper by itself is barely better than wood and stone, given how malleable it is. Your people will probably make do with wood and stone where they can, and import iron where you can't do without it; like swords, blacksmith's tools, carpenter's tools, and ploughshares. [Answer] Even say you have iron rich mountains (as kingledion pointed out, this isn't necessary to assume just because you have mountains) - mountains don't tend to be the best environments to support large specialised populations which can be bothered with or even have the need for extensive metallurgy. Much arable farming is unlikely - a hunting based society much more likely - they will have loads of leather lying around. [Answer] The most common armor in the Middle Ages was the **gambeson**, made of **wool**. It offered a very good protection and it was wonderful for cold weather. Your kingdom is, in fact, more historical than one with everybody wearing maille. And if they have a lot of **sheep** that produce good wool or **horses** with thick hair, it is the only logical reason. Usually, the natives use the best armor for their terrain and/or climate. The cotton armor of the Aztecs, hardened in a brine, doesn't look very good. But the Spanish *conquistadores* preferred it to their own metal armor. The same with their wood helmets, many Spaniards died from an arrow to the head because they took off their helmets as much as possible (one survivor was happy to have promised his wife that he would use always his helmet). In the 15th century, the most common armor was the **bringandine**, a leather armor with reinforcements of steel on the inside. Your kingdom could use them, or if you don't want them to have metal, even reinforcements made of bone, **horn** or wood. ]
[Question] [ I have designed the "blueprint" of an spaceport. I know that in Earth solar energy is 1.200W/m^2 approx., but my spaceport is in the space (no atmosphere). **Information** - My blueprint has 60 solar panel blocks. Each block has 100m^2 area, for 60 \* 100m^2 = 6,000m^2 total area of solar panels. - The spaceport is at 1 AU from the sun (149,597,870.7 km). - The sun is the same as our sun. - Spaceport always gets sunlight. - Solar panels are high-tech level, 80% efficiency. **Question** **How can I calculate energy output?** I would put a hard-science tag, but I don't think it is necessary. I only want a calculation formula. [Answer] > > Question > How can I calculate energy output? > > > **Not too reliably**. You start from the energy actually incoming on the panels. This is the **total solar irradiance** and is the black body radiation given off by the Sun. It actually depends on several factors, so a star "identical" to the Sun might be off by up to 5% either direction (the Sun is itself a weakly variable star, by about 0.09-0.15% depending on the source). For the Sun that value is [around 1365 W/m^2](https://en.wikipedia.org/wiki/Solar_irradiance#Total_irradiance). Now, the problems are the following: * your solar panels (*any* solar panel) will only capture a fraction of that energy, if we're talking photovoltaics, because the photovoltaic effect requires photon of a precise wavelength or, at the very least, some specific frequency bands. [![enter image description here](https://i.stack.imgur.com/wk8gY.jpg)](https://i.stack.imgur.com/wk8gY.jpg) To improve the yield you can re-radiate some waste heat, mainly due to the longer wavelengths in the infrared, through some Seebeck converters. But that adds to the mass and complexity of the station. * That energy will not be converted with 100% efficiency. You're probably looking at around 20-40% if using photovoltaics. There is talk of "quantum traps" rectennas made up of microscopic crystal "hairs" (a previous version employed carbon nanotube 'hairs') pointed towards the Sun, organized in such a way that an incoming photon would always pass through a hair-gap "tuned" to steal its energy, no matter what frequency it was. But even the theoretical efficiency for this setup is not 100%, but around 90-95%, because it depends on the re-radiation temperature of the panels; to achieve 100% you would need to cool them to absolute zero, *and that would take energy...* . * Conversion and storage efficiency. The panels will produce electricity at some optimum voltage, then you'll have to smooth, buffer and convert this energy to "pair" it to whatever uses it. Possibly you'll have to store it into batteries or capacitors and retrieve it later. All these operations will waste a percentage of the available energy. * *Wear and tear*. The panels are exposed to hard radiation and charged particles from the sun, and this is hard on many materials. Glass will slowly become more opaque, semiconductor junctions will slowly "corrupt". The decay rate for the ISS Solar Array Wings is [around 3% each year](https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20030068268.pdf). A reasonable, back-of-a-napkin calculation for energy yield would be around 400 W/m2. Having 6000 m2 available will then give you around 2.4 megawatt of power, and I think you can rely on two solid megawatts for most purposes for any reasonable time frame. Of course, inconveniences like severe coronal mass ejections and charged particle onslaught, high-speed meteoric dust or even, Lord forbid, Kessler syndrome could easily reduce available power either gradually or even catastrophically. A way to increase the yield and durability of the setup could be to set up the panels facing away from the Sun, and use a micrometer-thick Fresnel mirror to concentrate the radiation on the panels. The mirror would protect the panels, and it would be easier to replace; possibly it could even be [self-healing](https://arxiv.org/ftp/physics/papers/0301/0301053.pdf) (a corroded area of the mirror could be re-melted to erase pocks and scratches). Of course, the mirror performances in a vacuum then might become a problem. # Radiance calculation To calculate the irradiance you need to know the star's *luminosity*. Since energy is conserved, the total flux of it is constant through any ideal sphere with the Sun inside, and the flux through a given area of such a sphere only depends on the sphere's surface; the constant flux is "diluted" on a larger and larger surface getting farther and farther out from the star. The surface of the sphere is an easy thing - 4\*pi\*r2. So you divide the luminosity flux by this surface, multiply again for the surface of your panels, and get the fraction of energy that they intercept. Multiply again by the conversion efficiency and you get the power output. The difficult thing is calculating the star's luminosity. Usually this is done by approximating the Sun with an object known as a *perfect radiator* or *black body* (which stars, while close enough, really aren't). There is an equation known as Stefan-Boltzmann's equation that gives the total unit radiative power of a black body, which only depends on its temperature: $ W = k T{^4}$ with $k = {5.67} \cdot {10^{-8}} W m^{-2} K^{-4}$ and T, the temperature, is expressed in Kelvin. Supposing this is constantly radiated by the Sun's whole surface, the equation giving irradiance of a star of radius R and temperature K at a distance D is $w = {5.67} \cdot 10^{-8} \cdot {T^4}({\frac{R}{D}})^2$ (we get rid of the PI's) Solving for the Sun, where T = 5778, R = 695700 and D = 149600000 (1AU), gives us the value of 1366.7 W/m2. This is the mathematical answer for the Universe where [cows have spherical symmetry and uniform density](https://en.wikipedia.org/wiki/Spherical_cow). In the real world, [things are not so simple](https://physics.stackexchange.com/questions/130209/how-can-it-be-that-the-sun-emits-more-than-a-black-body). Plugging in the surface area of the panels A (in meters squared) and the efficiency factor (from 0 to 1), you would have a power output P, when the panels are new, of $P = {5.67} \cdot 10^{-8} \cdot {T^4}({\frac{R}{D}})^2 \cdot A \cdot \epsilon$ [Answer] The general answer is the following: Take the full power output of the Sun (in watts). Divide it by $4 \pi$ and divide it by the distance from the sun squared (in metres). They multiply it by the effective area of your solar panels, (if they block each other or are not directly facing the sun, they produce less.), and multiply with the efficiency. You get the power output in watts. Of course, your panels can't convert all the wavelengths the Sun emits, so you might would like to use the luminosity of the Sun only in visible light. So: $ p = \frac{L\_0}{4 \pi r^2} A \pi e $ where $L\_0$ is solar luminosity, $A$ is the area of the panels, and $e$ is the efficiency of the panels. But of course, if you only need it at 1 AU, the solar contant there is 1368 W/m2. [Answer] Well first off your number for solar irradiance or insolation of 1200 W/m^2 is for the surface, as you noted; in space it would be higher around 1361 W/m^2 without the atmosphere blocking some energy. <https://en.wikipedia.org/wiki/Solar_irradiance> Then this is fairly straightforward, to get the power output you just multiply the total area by the solar input times the efficiency. There were some math errors in you question 60 blocks at 100m^2 would be 6000 m^2 or if they are double sided as you seem to assume (which doesn't make much sense for a solar collector because one side would always be in the shade not producing energy) 12,000 m^2. For my maths I assumed single sided area of 6,000 m^2. 6000 m^2 \* 1361 W/m^2 \* 0.8 = 6,532,800 Watts or 6.5 MW To find energy you just multiply by how long it is operating, so assuming it gets constant sunlight, again fairly straightforward depending on what units you want. Super easy in the metric system where 1 watt = 1 Joule / second. 24 hours = 86400 seconds 1.15 MW \* 86400 s = 561 GigaJoules per day or for a more common energy unit the kWh that would be ~156,000 kWh per day. Note: I find that Google is very helpful for converting units, just type in the starting number then "to" whatever unit you want and it will bring up their unit converter, i.e. search for "561 Gigajoules to kWh" and it will do the conversion and bring up the tool which has dropdowns for other units. [Answer] This shouldn't be very complicated. The atmosphere reduces useful solar flux by ~20%. So correct for that. And make a better estimate about PV efficiency. 40% would be more realistic. So if you start with 1200W/m^2 on the earth's surface, multiply by 1.25 to reclaim the 20% and you get 1500, and multiply by 0.4 for your PV efficiency and you get 600W/m^2. If it's constantly exposed, you should see that consistently. ]
[Question] [ The story is as follows, a group of people (around 2000 from all around the world) leaves earth and lives on a different (earth like) planet for ca 6000 (earth) years. The planet is about 0.8 times the size of earth and has a similar gravity in the range of 0,8G to 1,2G. The planet has seasons, a year is about 4/5 of an earth year. The land masses on the planet are more fragmented than on earth, so there are 15 smaller continents and the distances between them are much smaller than those on earth. The people live in relative comfort, very few places have extreme temperature (like the poles and a couple of deserts) but the general climate is overall slightly colder than on earth. Loads of rain and fertile land but with obviously very different plants and animals. The planet is densely populated. ( <- I hope this improved my question, it is my first time posting) How different would they be in appearance to earthlings? Would it be possible for them to have developed a hair/eye color that doesn't exist on earth, or is the time frame too short? and if it were possible could it have become a majority trait? [Answer] They may appear to be a distinct people. This happens on a scale of a thousand years. Whether or not that’s [seen as a “race”](https://youtu.be/teyvcs2S4mI) depends on culture. Norwegian and Scottish and German look different and they’re all Caucasian. Hair or [eye color](https://en.wikipedia.org/wiki/Eye_color#Genetic_determination): it *could* happen. When it does, it is sudden. Look at the [“founder effect”](https://en.wikipedia.org/wiki/Founder_effect) for a major source of the colony’s shared traits. As for whether a new trait takes over to become the norm, look at the time to shared common ancestor. This depends on the colony’s size and how isolated the subgroups may be. But [I’ve seen figures of mere hundreds of years](https://youtu.be/jyknbCLys_8), so 6000 is no problem. [Answer] With 6000 years without being on Earth, physical changes could be due to cultural or political changes as well as purely natural changes that JDługosz stated. For example, Isaac Asimov, in the robot series, make a clear physical distinction between people stayed on Earth and those who live on other planets (Spacers). Even if terraforming made those other worlds similar to Earth, political and cultural differences are huge. Spacers are tall, handsome, and they live 400 years. They have cleared all diseases and germs, and they are massively using birth engineering to select best criteria for babies. Thus, I think if a "natural" cause does not satisfy the changes you want, you can easily base them on cultural differences (birth engineering, food, religion, ...). [Answer] You state that the colonists were from all around earth. It is not unreasonable to assume that there will have been a thorough mixing of genes in the descendants of those people, leading to a distinct look unlike anything we have here on earth today. While we have, of course, persons with mixed ancestry, it is rather uncommon to have more than two or three racial characteristics combined in one person, in any case, those are single individuals and not a whole people. [Answer] One thing you might think about is *environmental* influences on appearance. These might be much easier to make uniform (or majority) over a large population than genetic changes, given the restriction on how quickly genetic changes might spread without some outside circumstance like genetic engineering or founder effect. EngelOfChipolata touched on the possibility a bit when mentioning foods, but there are more possibilities. So, how would these environmental changes work? Depends on what you want done, I can think of a lot of possibilities, plus the possibility of several stacking up to form a pretty striking difference fairly quickly. * One option would be simple **bio-accumulation**. Something in the food, the water, or the air that causes changes. It could be as simple as the accumulation of some dye in the skin or hair or, heck, teeth or something - basically, the [carnation-in-colored-water](https://www.stevespanglerscience.com/lab/experiments/colorful-carnations/) trick, only for humans. Or more seriously, it could be something like accumulation of minerals or other compounds - I recall an [accumulation of silver](https://en.wikipedia.org/wiki/Argyria) can leave the skin a blue-grey color; and though it may be toxic in high dosages, it may be tolerable in lower chronic doses (and you people might more easily evolve higher internal tolerance or develop better treatment for the deleterious side effects without bothering about mere skin color). Of course, other minerals or compounds may cause different changes, some with greater side effects, others with few. * Another option could be **physical conditions** Something like slightly lower gravity could make the body development tend towards noticeably tall and thin. Something like varying levels of sunlight or the radiation therein could encourage very pale, or very dark skin - since the basic mechanism for that selection is already evolved. Some quality of air composition or pressure might gently influence nose shapes (due to the benefits of altered nasal air passages), or lung development (possibly altering torso proportions slightly). These kinds of adaptions can be seen in populations adapted to high altitudes, for example. Nutrition or lifestyle-based physical demands might shape height, weight, or muscular development. Of course, any of these adaptions are likely to be slight - genetics play a pretty big role in development, so environmental adaptions that are not genetic would, I think, average over a population (especially a widely dispersed one across many different climates) as slight modifications or tendencies rather than extreme ones - not to mention ones that have a decent chance of being already seen in one population or another on earth at some point in history. But, stacking a few of them together might make or help make a striking overall appearance shift. * Another possibility might be a **disease**. Something like [vitilego](https://medlineplus.gov/vitiligo.html) might do it - it causes patches of skin without melanin (the most common pigment) giving a patchwork appearance with dark and pale skin. Or something like, in one of Murray Leinster's [Med Ship stories](https://archive.org/details/pariah_planet_pc_librivox) there was a mild disease, which had piggybacked on a worse one, that had the primary symptom of causing blue patches on the skin. If the disease is very mild, people might not think about curing it, they might not even notice beyond the color (especially if they have other, immediate concerns at the time it appeared). And some diseases are inheritable. Otherwise, something like a virus (that meddles with DNA) might have a marker it leaves behind, that can as a side effect alter the DNA regulating skin or eye color in a way that makes it...produce unusual pigmentation. So anyone who caught the disease might have the color change, and any of their descendants might have it too, depending on the modification on question. That will spread a *lot* faster than inheritable mutation alone. Or, even more simply, some otherwise harmless bacteria which tends to colonize human skin develops some property altering color - depending on the bacteria and/or its environmental conditions, it might result in coloration alterations in patches, in specific areas, or over the whole skin. And, of course, some environmental effects can be a side effect of **certain practices** Foods or other optional applications may have an effect on appearance, even long lasting ones, but they would likely not be consistent over a large population or in different climates without some extra encouragement - like ritual or religious use, medicinal use, or other practical uses like cleaning, pest control, or the like that makes that specific product ubiquitous. So, maybe there's an oil that makes one's skin turn a bit more orange with every application, but people use it anyway because of health benefits (like sunscreen), or pest control (like citronella). Maybe there's a beverage that makes the eyes, whites included, turn a bit greener the more it is consumed - but people keep drinking because of religious ritual or just culturally accepted practice (ie, equivalent of alcohol - it does show up just about everywhere). Maybe there's a plant used for cleaning (like we use lemon in so many cleaning products, or like we use chlorine in cleaning the water) that has a pigment like henna does, making everything dye redder and redder as long is its used, and lasts long enough for the effects to be overlapping. The original colonists might not have cared about side effects next to the benefits - and later generations might not have known, especially if it is ubiquitously used. Or it might have turned into culturally accepted practice, interwoven in beauty standards or something. These effects will all be **limited** That is, some will occur only as long as the environmental influence is present, and may fade if the person leaves the planet, stops using the product, or technology finds a non-altering equivalent. Others may last a lifetime, since the change once made cannot be undone, but kids born without the influence will lack the trait. And still others may take generations to fade (if selected away from or genetically diluted), or may never fade at all without interference since the relevant factor remains present - the diseases which alter DNA or which are carried along and contagious or inherited by each generation. So, you might have a very striking appearance change that slowly fades as someone leaves the planet and/or its customs, and develops as someone moves there and picks the customs (and conditions) up. You might have kids physically different from their parents depending on the environment in which they're born. You may have an overall, very dramatic appearance change consisting of several elements, some of which are very immediate and some of which are more long lasting, some of which are present more in some cultures or areas than others. You may have evidence of historical influences on the changes - including manufacturing, medicinal knowledge, and fashion - as what is known about these factors changes with technology and common knowledge. And all of them will be varied by individuals, by climate or populations, and by the presence or absence of other environmental or cultural factors. Planet-wide, with a diverse population and many different climates, ecosystems, and lifestyles, you would likely find a lot of variation in whatever traits you choose - which can still be quite noticeable, it is just more likely to be slight tendencies, or frequency or populations with any given trait, or more visible in some people and less in others (possibly with social cues tied to the less and the more). [Answer] "developed a hair/eye color that doesn't exist on earth" Most likely no. Even if "orange" eyes would be an advantage - this won't happen so simply. It has to be a major advantage, otherwise orange eyes will disappear immediately. If tall people have an advantage and short people won't have that many children the population will become taller and taller. On "earth like planet" there is no reason to differ so much. Only "very different plants and animals" - those who have problem with food, have lower chance to survive - some different stomach could appear, tongue, teeth, but you want to increase the time frame to 10000 years to have minor changes on whole population, and to 50000 (or more) to have major changes like the number of teeth. (Even if I think the human system is pretty perfect and does not change on different continents on earth that much) There is also a small chance that humans will create two species (but most likely they will not) - [more info](https://en.wikipedia.org/wiki/Disruptive_selection) Also the available options increase with the size of population. [similar question/answer](https://worldbuilding.stackexchange.com/questions/76075/will-new-born-babies-on-mars-have-any-body-changes/76092#76092) Some sources: [Evolution](https://en.wikipedia.org/wiki/Evolution), [Natural selection](https://en.wikipedia.org/wiki/Natural_selection) ]
[Question] [ The world as we know it crumbled down yesterday. All stock exchanges were turned off. Capitalism as we know it failed. Answers to how and why this happened are outside of this question. It just happened. New leader emerged from the chaos. He has full trust of army and managed to, uh, "get things back to order" in few months. Again, how he managed to do this is outside of this question. Pavel, the new leader wants to use his powers and colonize Mars. We know human settlement on Mars is feasible, but very costly. Because Pavel now "owns" everyone who survived, he can just give you orders to work on this Mars Mission. If you listen to his orders, you have food and shelter guaranteed. If you disobey ... you will become "practice target" for the military. However, while Mars mission is feasible using today tech, lots of things needs to be done *perfectly* in order to actually land manned mission on Mars surface. Pavel himself cannot oversee every single detail of such mission, so he has to delegate to the army. And army can monitor if you do your work, but they certainly cannot monitor if you do it properly. It is almost sure that under dictatorship of "work or die" some people will do their job sub-par **Can you actually have successful manned mission to Mars?** Assume: * Military loves Pavel and does not want to have any other leader than Pavel * Military will try to fulfill every order Pavel gives them * There are enough people surviving initial chaos with sufficient knowledge to accomplish the task * Pavel is sole dictator of USA * Current technological level as of 2017 * All of NASA inventory and SpaceX inventory remained untouched during the time of crisis [Answer] There is some evidence that an absolutist dictatorship might be *better* positioned to pull off a large project like a Mars mission than a typical 20th century democracy. Historically, tyrannies have been very successful with large scale, major projects, even ones at the edge of technological capability. In ancient Egypt, the pyramids represented incredible investments of time, labor, and highly skilled engineering prowess, and they were built under the auspices of absolutist "god-emperors". similarly in ancient China, both the famous Great Wall, and the far more interesting world exploration project of the 1400s happened under absolute emperors willing to kill those who did not obey. In the case of the exploration project, a lot of comparisons can be made between an exploration fleet of the size and complexity developed at that time and a nation the size of the USA putting together a Mars mission now. We are talking about bleeding edge technology, a large crew to man the mission, unknown exploration in a dangerous environment, and ships larger than had ever been built in human history. Even the more well known Spanish and Portugese exploration efforts a few decades later were conducted under the authority of absolute monarchs who could gamble significant percentages of their nations' total budgets on very risky, high tech exploration efforts. In more modern times, the Nazi regime not only developed: rocket powered fighter planes, jet fighters, ballistic missiles, assault rifles, and tanks with hybrid propulsion systems while their opponents were still mostly relying on biplanes, they were also on the verge of developing an atomic bomb, and would likely have done so given only a couple more years. Famously, the USSR, after a totalitarian regime took power and drove millions of people into slave camps in Siberia was able to radically upgrade it's national infrastructure and technological/industrial base. The Soviet Union, right up until the end of it's tyranny, was able to make MORE rockets than the USA, BIGGER rockets than the USA, and in some cases more sophisticated rockets too. They did fall behind in innovation over the long term, especially with the microchip revolution in America, but the USSR was always able to throw large amounts of resources at massive, high tech projects with a good deal of success. The failure of these systems usually stems not from their ability to win a "space race", launch a huge battleship or create the world's largest gun. Generally, their failure comes as a result of the misallocation of resources to such grand projects (like your Mars mission) while common people have to stand in bread lines, wait years for an automobile, sometimes starve, and get more and more unhappy because they are assigned a job for life whether they like it or not. There is no real contradiction between technological advancement and tyranny. Engineering may have a creative side, but engineers under extremely oppressive regimes throughout history have proven capable of developing some VERY impressive advances. Obviously, if your regime is under such pressure that it resorts to assembling V-2 missiles in underground tunnels with slave labor on loan from a concentration camp (as the Nazis were compelled to do) the quality of work will degrade to such a point that there will be more explosions and crashes than successful launches. This may explain some things about the peculiar North Korean nuclear weapon program with it's numerous, strange failures. [Answer] History proves that no dictator, regardless of how ruthless or all seeing, can *ever* guarantee a scientific success on the edge of the technological and scientific frontiers. The only way to guarantee success is simply to keep trying when failures happen. The problem for any dictator doing this is simple : you will, if you hope to succeed, put the best people on it. If something goes wrong, at what threshold of it going wrong can you afford to get rid of the people (or your hold on them, e.g. their families) ? After some failure, they're *still* your best likelihood of success, so getting rid of them is a bad idea. Punishing them (directly or indirectly) for a failure that's simply one of the consequences of pushing into the unknown is not going to change the results. Pragmatic rulers, dictators or otherwise, do not refuse to accept any failure. As an example : Hitler "fired" Field Marshall Von Rundstedt after failing to stop the Normandy invasion. But he wasn't long gone when he was brought back to stop the Allied advance. And Hitler was probably the *least* pragmatic dictator you could think of. Space colonization is really going to be very hard. One way you would make success more likely is to *first* crack a lot of other "small" problems. Survival in the long trip to (and from) Mars. Developing safe ways to live on a hostile planet (and you'd start with the Moon). Developing food that can be grown or manufactured from local materials, but that problem requires detailed knowledge about the resources available locally. This takes time - decades - regardless of resources made available to do it all. So if "Pavel" is serious, Pavel is either going to have to be patient or Pavel is going to run out of people who can do the job very quickly. Don't underestimate the willingness of scientist and engineers to do their jobs to the best of their ability under a dictatorship. The best of them (intellectually) will normally also be the most keen to succeed in their own spheres, and they will drive projects more efficiently than any ruthless dictator could. If you'd ever worked for or with some of these people you'd know how single-minded and even ruthless they can be themselves. Scientists aren't, by any means, all humanists. [Answer] The easiest would probably allocating lots of funds towards what many space organisations are already doing, this can be accelerated by forcing companies like Lockheed Martin, Boeing and SpaceX to cooperate more closely. It would be quite likely that there are still many people enthousiastic about space exploration, even if they don't detest the current regime. Dislike of the current regime might actually motivate them *more*, as it is much easier to commit a coup in a community that has only a few members, like a Mars colony. And if the colony is self-sustaining, it would be well beyond the reach of Pavel's regime. For other ways to motivate people we only need look at other dictatorships, where threatening someone's life or family seems the preferred method of motivation. To completely tie the fate of the engineers' family and their rocket together, (some of) their families will be the first passengers. [Answer] A military junta has happens many times in the past, including one of the most famous juntas of the recent past, Nazi Germany (Although that is contentious because it could be argued that Nazi Germany had considerable civilian leadership). Certainly a military junta can carry out any government function including large community projects. You will note that even under dictatorships, there are people that will excel because of the love of their craft, this includes scientist, engineers and soldiers, your three ingredients for a space agency project. For example the world still uses the invention of Mikhail Kalashnikov automatic rifle model 1947. The problem with juntas is not the terror or heavy handedness from the point of view of those in power and the craft people who are needed. The overthrow comes from the peasantry and the bourgeoisie who want more freedom [Answer] **It is going to work splendidly.** ***Pavel has ample budget:*** No need for marketing or advertising any more, all capitalist economic slack can be devoted to the 5-year or 10-year plan. ***Not that big a budget needed:*** NASA went with 99.99% surety, but Pavel has astronauts that will work below that so progress is ensured at much lower investment. ***Volunteers galore:*** Previous political adversaries can work off their debit by graciously providing input to the one game in town that gains you real credit with the new administration! ***Risk.*** What is most important for this truly fertile situation is to balance risk and speed. Velocity of the project after all will be as decided by Pavel and his delegates. Science and engineering will facilitate. ***Avoid failure.*** I recommend a series of 5-year plans with solid goals in space. Having for example a space station in orbit that is planned to be self-sufficient, first for a year, then for two years, you know what you have before you punch it out of orbit towards Mars. ***Ensure success.*** Have, say, three or four concurrent projects. While dividing the resources it will give healthy competitiveness and one fireball in the sky will be disaster for just one project with that other parts of the program silently cheering. **Think "We choose to go to the moon". Our President Pavel knows the way.** [Answer] It's absolutely feasible to get a manned mission to Mars. We have several clear paths in the form of various program plans that could feasibly get us there. We could start on it today (or 30 years ago for that matter) and have quite a good chance of success. There would be problems, many of them unanticipated, but as far as we've looked into the issue there are no unsolvable showstoppers. The problems that are likely to crop up are ones that can be solved by engineering effort - in other words, a question of time and money. It would be harder to justify a Mars mission as *not* being possible than to justify it as possible. Since in your case there is no lack of will or funding, absent some completely unexpected curveball that the universe throws at us, they're going to do it. There's no guarantee that a particular mission won't fail, but if the will remains, they will try again. It may be delayed, but it most likely will happen. [Answer] Bust out 1984 and take a read. How do the citizenry know what their government is doing? How is the war going? Is there a war going? Who is it with? Consider how North Koreans are apprised of the doings of their government. Do you think they consider the endeavors of their government successful? Citizens can judge what they see in the grocery store or how the new apartments look, but what about the nuclear program? How do the North Koreans think that is going? Read the conspiracy theories about the moon landing. Good stuff. Not entirely implausible. My favorite part of World War Z (the book) was the electric machines that exploded zombies with bolts of lightning - not the machines themselves but why they were built and ballyhooed. Actually almost all zombie killing was done with axes made from car frames, but the lightning cannon footage made for great PR and improved morale. It is much easier to mock up a Mars program or a foreign war and have it go exactly as you like than it is to do it for real. Likewise the program to crush the evildoers of Oceania. Even if you do it for real, the mockup can help get past rough spots you might not want to advertise. The real costly endeavors should be reserved for things that the citizenry can actually perceive: bread, circus, thought police. ]
[Question] [ Let's suppose anti-gravity/gravity-manipulation/telekinetic technology is found in the near future. It allows to move large ships (thousands tons) into space from the surface of the Earth with relative ease. However it comes with nasty side-effect - any electronic device within "field" is short-circuited. Question is: **Is it even viable to continue space exploration without electronics?** Using human brain (crew) and mechanical devices and (if possible) chemical mechanisms? There are obvious problems like navigation, communication, telemetry... Can they be overcome? Or gravity manipulation will be abandoned and people would look for another technology for space travel? **EDIT:** Thanks to commenters! As it was pointed out - electronics can be used when engines are turned off. What if we increase difficulty a bit - engines ("field") can't be completely turned off (like nuclear reactors can't be stopped fast), or they need a long, energy consuming process of warming up/cooling down so it prevents to switch mode during spaceflight. **EDIT #2:** Thanks for comments! Main goal for question was to justify somehow consistently "advanced on planet civilisation and primitive space naval type battles like in the first half of 20 century", without cultural or law limitations. Probably i ll make another question with this specific goal. [Answer] Orbital mechanics isn't that difficult to work out if you have a background in mathematics. [Just take a look at some equations on Wikipedia.](https://en.wikipedia.org/wiki/Orbital_mechanics#Laws_of_astrodynamics) You could do these by hand, or have a mechanical computer do the work. It won't be terribly accurate, but spacecraft on interplanetary trajectories routinely make correction burns despite their razor-thin fuel budgets. If you can easily haul a massive ship into space, you probably have enough of a fuel budget to be sloppy. Flight control (Both navigation and ship control) is more difficult but solvable. [Apollo featured a telescope to help it get its bearings](https://en.wikipedia.org/wiki/Apollo_PGNCS), and given the primitive state of computers at the time it might not be too terribly difficult to come up with a mechanical counterpart. Your ship obviously can't be fly-by-wire, but if you keep the design simple and limit the number of thrusters (Or rather, keep all of the thrusters centralized along your primary axies, so they only impart one movement/rotation), you can greatly simplify the ships controls. For purposes of pilot comfort installing a mechanical autopilot that nulls out rotation is a good idea. Radios might just be the easiest thing on this list - They've been around far longer than computers, and nothing about them requires electronics as we think of them today. Now, a lot of people in your comments suggest just turning your electronics off. Assuming this doesn't work in your setting, you can launch the hull of your ship using your Anti-grav, and then send up conventional rockets with the electronics it's going to need. That said, a system that can cheaply and easily lift thousands of tons of spaceship into orbit is going to be a fantastic interplanetary engine, so you'll probably want to keep using it. Final thing. I assume that it 'fries' electronics by inducing charge differences in the circuitry and creating damaging electrical arcs. What does it do to humans? [Answer] Spaceflight was described in fiction as far back as the Victorian era (actually even farther back, but without any sort of technical or scientific understanding of space), so it is quite possible to imagine a "steampunk" spacecraft using mechanical and fluidic devices to run the systems, calculate the trajectory and so on. Even into the 20th century, the idea of manned spaceflight was predicted upon the need for a team of technicians to keep the equipment running and a human pilot to guide the spacecraft. The entire RoBo (Rocket Bomber) idea was based on the principle of a manned spacecraft to deliver an atomic bomb on target from space, since electronics (and of course mechanical computers) would not have the accuracy or ability to adapt during the very short mission. Now multiply by how many days a mission to the Moon or Mars would take, and you understand why von Braun's 1950 era conception of a Mars mission took a fleet of ships carrying 70 men. [![enter image description here](https://i.stack.imgur.com/6yLct.jpg)](https://i.stack.imgur.com/6yLct.jpg) *USAF RoBo concept* [![enter image description here](https://i.stack.imgur.com/2rWO1.jpg)](https://i.stack.imgur.com/2rWO1.jpg) *vonBraun Mars Mission fleet* Really, the only thing that prevented a squadron of USAF rocket bombers becoming operational in the early 1970's (projected timeline) was the invention of the transistor and development of rugged and reliable microelectronics that could replace the pilot. So if there is no development of microelectronics, then spaceships will need human crews doing jobs like astrogation, engineering and all the other tasks that a traditional ships crew is needed for. [Answer] Navigating and communicating through space should be doable by teams of people. They were doing it on the high seas for millenium before we took to the heavens. The problem with space though is that people like to eat, drink, breath, and not freeze to death. Navigation and communication doesn't work very well with dead people. So you'd need a way to insulate the interiors from the cold exteriors and you'd need a way to produce oxygen and food/water. You could do both with large hydroponics chambers and a hydraulic system that powers circulation fans and ferries waste and clean water to appropriate locations. Recycling and reclamation technologies would need to be biological, self regulating, and highly efficient. [Answer] > > Is it even viable to continue space exploration without electronics? Using human brain (crew) and mechanical devices and (if possible) chemical mechanisms? > > > Frank Herbert's *Dune* outlines a precedent for this. While it not completely denies the existence or function of basic electronics it establishes a strict rule against Artificial Intelligence: "Thou shalt not make a machine in the likeness of a human mind." This chief commandment then in turn leads to the development and perfection of "human computers", the *Mentats*, claiming to being superior to the ancient thinking machines. One way to make space flight work is to replace simple electronics by other means, say pneumatics to control machinery, and have the "heavy computing" for navigation and telemetry done by improved human brains. Going even further, the *Spice*, a substance to extend the human consciousness is used by the *Guild Navigator* for a heightened awareness and a prescient ability to see safe paths through space-time, thus allowing to navigate in space. I will argue that in any case the power of the human brain (expanded consciousness or not) if harnessed properly beats steampunk mechanisms for any advanced calculations. [Answer] Mechanical computers exist - assuming that the calculations are standard, you'd likely have standardised mechanical devices meant to do *parts* of calculation and do the rest by hand. Navigation/position taking with starcharts (which is where it gets complicated. these things would be bulky and depend on your region of space, and sextants for taking readings). I like the idea of charts and a whole rack of numbered *[curtas](https://en.wikipedia.org/wiki/Curta)* - you have a manual telling you which ones to use and you'd basically start with #1, do calculations, pass on the values to a second and so on. Something worth considering is the classic starships were small and cramped. Having to carry charts on paper and mechanical calculators might be something plotworthy, Perhaps having your navigator's quarters described as 6 walls of chained down books, and a wall of mechanical calculators, kept in zero G for easy access [Answer] [This](https://en.wikipedia.org/wiki/Apollo_Guidance_Computer) is the computer that was actually on Apollo 11. It had 32k BITS of ram (not bytes! bits!) and about 600,000 bits of ROM (permanent memory, equivalent to a hard drive.), which is the same amount of information as about 50 pages of a printed paperback novel. You're not loosing that much by leaving it at home. All the math and calculation for that mission were done ahead of time. As for communications, there were definitely radios before the transistor, and people did plenty of [navigating by the stars](https://en.wikipedia.org/wiki/Polynesian_navigation) while not having the technology of, say, metals. In addition to strictly mechanical computers, there are some other possibilities. There are vacuum tubes. These can generally handle a significantly higher surge current than a tiny silicon chip, so perhaps they could be tough enough to handle the 'field' of your engines. Then you could basically say that vacuum tube technology has advanced so far, and set your computational abilities any way you like. Also, there were computers that run on switches and relays. These are called [electro-mechanical](https://en.wikipedia.org/wiki/Harvard_Mark_II), and their design would make them even more resistant to the engine 'field' [Answer] You want to investigate RUSSIAN science fiction from the 1950s. Isaac Asimov had some good translations of some of it that I read once... the Russians used mechanics the way we used electronics. Where we would have radio signals to communicate between Mars and Earth, they had high-speed rockets carrying cans of microfilm. Mechanical television is possible (British had a working model of that just before RCA made its big electronics breakthrough). There's a bunch of other examples I've heard of. So I think the answer is "yes, certainly." ]
[Question] [ So we discover an alternate Earth, inhabited by humans, whose technology roughly corresponds to that of our late middle ages (think 13th or 14th century). Surprisingly, those people do not believe in magic, nor in fact have a concept for it. Things either happen because people do them (you have to sow in order to reap), or because that's the way it is (spring comes after winter), or because the Goddess so wants (that's why our army defeats our enemies). Praying to the Goddess is useless, praying to other entities useless and heretical, reciting incantatory formulas isn't an idea, etc. Is this possible, or would it be too much of a stretch? What could cause such a state of things? (One Earthan scientist, a geologist, made the most elegant hypothesis, unhappily made in jest, and unacceptable for everyone else: they don't have a concept of magic because there is no mana in their world, as opposed to Earth. Unfortunately, no one could come with a better idea...) [Answer] ## Magic fills a gap in our understanding of patterns Humans (and probably any intelligent species) are hardwired to detect patterns. Not just in the moment (that silhouette looks like a tiger!) but also in time, linking a sequence of events together. It is an essential part of learning: *Eat pink berries - feel sick, eat purple berries, feel good.* The problem is that we see patterns all the time where there really are none: *I slaughtered a goat - the rains finally came. I can make the rain come by slaughtering a goat!* Most of these are unlearned when they are not repeatedly successful, but if other people hear of your pattern and have their own remembered patterns, they reinforce each other. With no way to explain how such a pattern actually works, we imagine it's "Magic". A second aspect is that humans are also hardwired for social interactions, meaning we automatically infer other people's intentions and emotional state from their expressions and actions. This filter can also be triggered (wrongly) by other events and lead humans to imagine spirits and gods. *Lightning struck Oona's hut at the top of the hill. Someone must be angry at her.* ## How to have humans without the concept of magic Doing without pattern recognition is out of the question, as the humans would probably never have made it to the stone age development level. Having an advanced understanding of physical laws (as we do in the modern age) doesn't quite fit with the medieval theme. "The Will of the Goddess" is actually quite useful to explain most patterns, but the danger is that humans apply human motivations to Gods (because we're hardwired to do that) and inconsistencies will lead to questions and then likely to the idea of other powers... and magic. To have a satisfactory explanation for all the weird and inconsistent patterns humans see, an abstract concept works best. Karma is a good example, though because of it moralistic nature it would greatly change the nature of society. The basic idea works though: Anything (good or bad) happening to you happens because of something in the (unknowable) past. You can make up your own more neutral concept, say "Flow", inspired by water : It can keep your plants alive or wash away your village, it doesn't care. Whenever there is an obstacle to the flow, there will be eddies and swirls, which manifest in the form of all those patterns we perceive but don't understand. The critical part is that it is so abstract/inhuman/complex there is no way to influence it. Trying to change the Flow is like standing in the river pushing the water aside. It will simply flow around you or drag you under. All together, people wouldn't need the concept of magic, since any pattern can be explained by either the will of the Goddess (if the event makes sense from our ideas of what She would do) or just "Flow" at work if it doesn't make sense. [Answer] I wish I could say that this could totally happen, but the fact is that it's unlikely in the extreme - at least as far as humans are concerned. Some other species might lack the imagination, or emotional triggers which leads to superstition being adopted, but humans have it all in spades. Quite simply, the reason we moved away from religion and superstition is because we started to better understand the world around us. This is a very recent shift as far as the span of human history is concerned. Remember that these medieval humans will have been descendents of even more primitive people. People who would have beheld the stars in the sky, the power of natural disasters, and depended on the weather to grow crops and survive. When you don't understand how the atmosphere works, or what causes plants to grow and thus provide you with the food your family needs to survive it's very easy to fall into the trap of blaming your good or ill fortune on otherworldly beings. Adopting a view that the world is what it is, and everything is based on action and reaction would require society as a whole to very fundamentally embrace a method of thought which doesn't come naturally to the uneducated mind. The only way I see this working is if your society is fundamentally different from ours going back several centuries, such as everyone being educated to a point, and their religion itself being very technocratic, and generally revolving around machines, and engineering. And even then, it's very likely that many people would start regarding technological achievements as being granted by the gods, and the engineers themselves not as inventors, but as priests who are guided by said gods. Take a look at the "Thief" series universe (the older games, not the most recent one which totally rewrites the universe). There too you have a technocratic and a magic based faction battling each other for control. [Answer] This would heavily depend on your definition of magic. If a human gets sick(Say a cold), but has no way of knowing about microorganisms(virus in this case), how does he explain it? The problem is: "any sufficiently advanced technology is indistinguishable from magic". You need a fundamentally different "human" to remove the concept of magic. One that doesn't try to explain things around himself. Because to explain something you don't understand, there's a good chance you're explaining it wrong. And explaining things wrong usually ends up as magic. [Answer] **All Humans are now Vulcan's!** basically, since magic was used to explain the unexplained (because explainable things are frightening), If some plague went through that only cut off a human's ability to feel emotion, they would become completely logical. (They may believe fantastic things could exist, but once faced with hard facts, they would drop the notion. They would also put in more effort to find out What/Why something was.) [Answer] Superstition is pretty closely related to the unpredictability of life. The fewer surprises people have, and the more people understand what does happen, the less they need an alternative. So, if the environment was very stable (same weather every year, crops never fail, etc.) and education even on a folk basis was adequate to explain what people experienced, there might be very little magic or religion. [Answer] As I see it mad science and wizardry are pretty much the same thing, in both cases someone has knowledge of a phenomenon and know how to exploit it but they don't really know exactly how it works. The only way your people could lack the concept of magic (or mad science, same thing) is if they lack the concept of the unknown, so perhaps said goddess does answer prayers and has been answering every question asked of her, leaving only the most incredibly obtuse questions unanswered, those being the ones where the answer cannot be given in a way people can understand. I'm educated, fairly intelligent (at least I think so) and curious but in all honesty quantum mechanics baffles me, my engineering and programming brain just cannot accept a non-deterministic universe. [Answer] Actually, why SHOULD they lack an idea of magic? You said they know that everything is done because of natural reasons. So I suppose they believe in a "natural" Godess (some sort of "Avatar of nature"). But even this doesn't contradict the idea of magic. Because if they believe in things they see, and try to explain each and every thing with natural reasons and if they see e.g. psychokinesis (even in our world there are some examples of "possible psychokineses" like Nina Kulagina or Swami Rama) or spontaneous human combustion aka SHC (there are also examples even in our world) they can name such things as "magic". But may be, just may be, they are more clever than us. They wont call it "supernatural" (so their scientists will think that it is bull\*\*\*t). Rather they may call it "rare occuring and unexplained natural phenomenon" (If magic or gods really exist in any possible world, they are, in fact, natural, not "supernatural"). PS. I hope my post won't raise another atheist - religious holy war against me. Please, don't start it. I heard both sides. I'm tired of this war. There shouldn't be any... [Answer] If it is always possible to explain any unknown with: **"the Goddess so wants"** Then it could be possible. The belief in a all powerfull unknowable Goddess, who rules all and works in mysterious ways, could make the idea of magic redundant. [Answer] Magic is originated from legends, tales, fairy tales, anecdotes, and the fear of the unknown. While it also depends of technologic advancement (gunpowder might seem mystical, for example, if you can't or don't examine it\*), cultural factors also heavily play role in it. Christianity, for example, oppressed several concepts of magic, but also created others, when it was coming to faith in satanism and witchery, for example. Either way, you have to manage a fragile balance of tech and culture, as ordinary people **really often** tend to believe the supernatural, and may even start spreading the word. Consider banning such things, for example - but the rest is up to you! \*Gunpowder is not the best example, as it's clearly a man-made material, but what if others have invented it before? Like the Chinese in real life. [Answer] Simple: Don't have religions that persecute scientists, and you won't have a Dark Age. Also, **don't burn books** (I'm talking about the [Library of Alexandria](https://en.wikipedia.org/wiki/Library_of_Alexandria), not the Nazis, but them too). Imagine where we'd be now, if the internet burnt down sometime in the 90s and we had to start all over. We'd still be trying to catch up to where we were in the 70s. That's what happened, circa 48 BC ~ 642 AD. Centuries worth of knowledge were lost in that library, and it took centuries to get most of it back. Knowledge *is* power. **The stretch here is** (other than there not being *those types* of religions) that you have people in power willing to lessen their hold over society, by never hindering the progression of science or the dissemination of knowledge. Imagine where we'd be if Earth's greatest scientists didn't feel they had to publish their best works posthumously, from fear of heresy. It is generally accepted today that magic does not exist, but for no other reason than **because we know better**, which came via platforms from which consensuses were drawn and made known to the masses, and are indisputable though sheer logic (and most importantly, reproducible according to the scientific method). In a single word, *what would cause that?* (and what *has* caused that?) : SCIENCE. [Answer] ## They don't have the idea of magic, because they have actual magic\* **\*or at least psionics** Let's start with this premise: 'the idea of magic' is inventing fictional and supernatural explanations for things that they cannot explain. Whether it is because they don't have the scientific knowledge or methodology to try, or some other mental or social reason, instead of trying to figure out the mechanism behind lightning (as an example), it gets blamed on witches, gods, or spirits. So what if they had a supernatural (at least to us) way to study the universe? They can use their spells or psychic powers to detect the build of and release of energy, resulting in lightning. They might not know (yet) about electrons or resistance in measurable terms. They might not be able to store electricity and use it to power machines. But they have a basic factual understanding of how lightning happens. And they similarly understand that static is the same thing. Even their own power could be basically explainable to them, so they don't need to come up with stories about it. It may be magic to us, but it is not to them. Assuming it is magic and not some form of psionic powers. That might even contribute to why they are at a medieval level of technology. If their powers provide them with other utilities, they could have less incentive to invent. And if they already have said basic scientific understanding of nature, physics, chemistry, etc. they would have less need to experiment and stretch the boundaries of their knowledge. But this is probably not what you were looking for. So I'll reiterate the idea of the mean, nasty Goddess worshippers beating it out of them. ]
[Question] [ Let's take 4 or 5 survivors living on a more or less friendly island. They have a cosy camp, a source of water, some food and stone tools. They are here for several weeks/months and know they will probably never been rescued. They're thinking of long term survival and one of the survivor find iron ore in a bog near the camp. Do you think they will be able to create iron tools using this ore? I think a furnace is kind-of easy to do but shaping and sharping metal sounds difficult with homemade stone tools only... I remember [this picture](http://orig15.deviantart.net/58c6/f/2012/243/f/2/raudan_valmistus_by_jarkko1-d5d2l2v.jpg) showing someone creating a knife from "nothing". What do you think about it? [Answer] **TL;DR: Probably, if they knew exactly what they were doing. And for a certain value of "iron tools"** ### Smelting The technology for smelting iron goes back millenia; relatively primitive tribes in northern Europe were able to do it after they figured out how - all you need for that is iron ore and high temperature. Basically, the device you will be trying to build is a [bloomery](https://en.wikipedia.org/wiki/Bloomery); a kind of a kiln where you mix fuel with iron ore, set them on fire and raise the temperature usually by driving air in with a set of bellows. Doing this will get you a bloom of iron which you further process basically by hammering it to produce wrought iron. This is a far cry from modern powdered steel, or even crucible steel (which you might be able to figure out later after you've gotten your first generation of iron tools), but it's incomparable to anything you might find just laying around. ### Forging After you've hammered the bloom into an ingot of wrought iron, you might want to shape it into something useful. This will be a slightly trickier part; for this, you need a forge, an anvil, some tools (most prominently tongs), a hammer and some grinding implement. Building a forge is not terribly difficult; it's really just a bigger fireplace which you fill with charcoal and drive air into using the bellows you had for the bloomery. A good big piece of hard stone may serve you for an anvil, but its durability will not be great. You may break it in the process, so a better anvil might be one of the first things you'd want to make out of iron. Tongs are pretty tricky. The only material you might have before iron that would be halfway useful would be some tropical hardwoods, bud make a couple of sets because you'll literaly be burning through them. Hammer is not much better; you may be able to grind a stone hammerhead, but it will wear quickly and the heat shock may shatter it. Have a couple prepared, and it may last you through your first product. For grinding, you can just find a whetstone. It will work almost as well as low-end modern grinders, but will take *a lot* of elbow grease to get anything done. But yeah, you can make some iron tools (probably starting with an anvil, hammer, and a pair of tongs) and just iterate from there; each new tool you make will help you make a better one next time. ### Shopping list For an end-to-end primitive ironworking pipeline, you need the following: * Iron ore (bog iron you described should do) * Coal (charcoal will work and is not difficult to produce) * Bricks (for the bloomery and maybe the forge) * Bellows (can be made out of some wood and some leather) * Some rocks (for a primitive anvil and hammer, and a whetstone) * Hardwood (for your first sets of tongs) ### Summary It is technically possible to make iron, if you're already familiar with the technology and have an idea of what to look for. It will be work intensive. The quality of metal you produce will be crap even by mediaeval standards. Nonetheless, it will be a huge step up from stone tools or whatever you may found laying about. If you want to take shortcuts, you could try using copper first and casting an anvil or a hammer to start with. It's not great, but better than rock. If you can scavenge and recycle iron from whatever ship or boat or airplane that got you on the island, it will be enormous help; even the crappiest steel we make today will be better than what you can make on a deserted island, and having tools made of it will give you a huge leg up. It might be possible to figure out how to make crucible steel, which is a significant step up in quality over iron, but that is a much more involved process that may take years to get right unless you know *exactly* what you're doing from the start. [Answer] (note: I'm no survivalist but it happen I spend much time on a mostly desert tropical island) I cannot find back the story, but I read that it is estimated that a man drop naked on a desert island would need 30 years to forge a needle. I think main problem would be: ## How do you recognize the right rocks/ground If you have no geologist in the group, you would need month of trial/error before you find the right soil to make a simple brick. And only then could you think of a oven ## How to reach iron melting temperature Once you have the oven, to make charcoal is pretty straightforward. But to melt iron? Think about it: during thousand of years, people relied on bronze. It implied to find copper and tin which are both less comon than iron. Then combine them The reason is not than they never thought about other metal. The reason is that you need to achieve very high temperature (1500°C) ### Edit: This video demonstrate how to smelt iron with VERY basic material. But the result is not exactly a neat iron ingot <https://www.youtube.com/watch?v=VVV4xeWBIxE> Using anything but anthracite or coke will result in very poor quality(brittle) iron as impurity in the fuel (mostly sulfur) will bound to the hot metal. ## Food, housing etc... To make and maintain a house take time. the first month will probably be only that. And even on a paradise island, it should take about 2 hours/person to get food and pre-boiled water. ## Edit: What if you forget about iron and melt aluminium This does not have this "let's start from zero" appeal, but crash survivors would have access to metal alumium from the crash site. And heaven on a remote island, you'll probably find enough beer cans to make crude tools. Aluminium alloy melt around 700°C. That's pretty easy to achieve. Once again, watch this video to make a furnace more than able to melt aluminium <https://www.youtube.com/watch?v=VVV4xeWBIxE> Remember that the tools you probably have in mind are from a society where steel can be cheaper than water. [Ötzi had a functional axe with only a few grams of copper.](https://en.wikipedia.org/wiki/%C3%96tzi#/media/File:ReconstructedOetziAxe.jpg) One aluminium can provide enough material for a good tool. [Answer] Given that your steatment seems to imply that they reconized it, I suppose that someone in the group have some basic skills in metallurgy, so if the group find the iron ore I would say yes, they probably should be able to create some pretty basic iron tools like a knife blade or a primitive harpoon, and with some luck probably a hammer. The tools will be pretty primitive, low quality and with low resistance and durability but on the other hand if they don't had anything else, they can be usefull. [Answer] Jules Verne addresses this very question in his novel *The Mysterious Island*. In this story, a small group of people are stranded on an uncharted yet hospitable island for months, with barely more than the clothes on their backs. One person in the group is an excellent engineer, who guides the group in building the tools to build the tools. Over the course of the book, the castaways climb the tech tree from mud bricks to a fully functional wired telegraph network. Based on Verne's writing: Yes, your castaways could work the iron ore, as long as they know how to develop their collection of tools all the way from stone knives to iron picks. It takes several steps -- and it is doable. [Answer] Well, it is definitely doable. The guy from [Primitive Technology](https://www.youtube.com/channel/UCAL3JXZSzSm8AlZyD3nQdBA/featured) has already successfully smelted iron, though he's yet to actually make anything with it. The order he made thing was: 1 - [Charcoal](https://www.youtube.com/watch?v=GzLvqCTvOQY) 2 - [Forge Blower/Forge](https://www.youtube.com/watch?v=VVV4xeWBIxE) 3 - [Furnace](https://www.youtube.com/watch?v=u7wAJTGl2gc) 4 - [Improved Blower](https://www.youtube.com/watch?v=JgQ-07VgJuY) As you can see, the only "civilized" thing he uses is his clothes, so it would definitely be possible to smelt it. [Answer] In [this video](https://www.youtube.com/watch?v=u7wAJTGl2gc), an Aussie guy makes a natural draft furnace from only wild materials. I happen to know a fair bit about survival and primitive skills and the like, so I'll just explain roughly what he does here, plus a bit on how to make the metallic iron into a tool. So, the first thing to do is to dig a shallow hole, which can be done fairly well with just a blunt stick, to make the base of the furnace. Then make a circle of stones for the floor, ideally about 25 cm in diameter. Now to get the material. For this, you could get clay from a riverbank, a termite mound, or (Since you mentioned that there was a bog nearby), turf. You'll need a lot of this. Throw the clay into a large pit, pour a little water in and then mix it with a long stick. Then you'll need some kind of fibrous material (He uses palm leaves), which you should break into pieces and sprinkle over the churned, muddy clay. Take the clay - which should be wet and gloopy - to your base, along with a vessel of water to moisten it if the need arises. Rub it onto the circle of rocks until it's smooth. Now you can start to build the wall. Lay the clay around the 25cm circle of floor in a thick ring, leaving one section open. Keep on stacking clay on top of this ring, and after about 3 layers you can start to build over the open section too, forming a door-frame-like structure, but first lay rows of twigs underneath it so the clay doesn't fall in. The clay will take a good while to dry, so you're probably only gonna end up doing a few layers a day. You should only add another lay after the ones below have hardened, and keep going until the furnace is about 175cm high. Then what he does is makes something called a tuyere, which is an air pipe, out of clay. Stack a few layers of rings of clay to make a cylinder 7.5cm in diameter. The next thing to do is to block the doorway, which you can do with more clay. However, make sure you leave a space to put your tuyere, which he puts into the doorway at a 15 degree angle downwards. When you're happy that the doorway is sealed and the tuyere nose sticks into the inside of the furnace, you need to find your ore, break it into pieces, and roast it. To do this, make a type of cooking fire called a criss-cross fire. Basically, you light your fire, and then lay a lattice of logs (Leaving enough space for the air to flow through) on top. Crush the ore to a powder and collect it in a container. Now, you need to make the furnace fire. You can use wood, but charcoal works best. I won't go into the details of making charcoal, but it's more or less lighting a fire under a big pile of wood and making a clay shell over it, then breaking it open the following day to find your charcoal. Stack the charcoal all the way up to the top of the furnace, and then light it on fire at the top. The tall, narrow furnace creates a strong natural draft, and temperatures inside could get to 1,200 degrees centigrade, if not higher. After an hour and a half of burning, the flames will eventually burn out. When you think it's cool enough to do so, take away the door-stopper and the tuyere and see if there's metallic iron at the bottom. If there is, make a mold from clay in the shape of the tool you want to make. Melt the iron in a really, really hot and fire and carefully pour it into the mold, making sure not to burn yourself. This is enough to give you one fairly good iron tool, but banging the metal with a hammer of wood or stone while it's hot will help shape it a bit more. If these guys are experts in primitive skills, technology and survival, they could potentially do this, but it'd require tremendous expertise to carry out in practice. ]
[Question] [ What law of physics needs to change in order to create nuclear (proton-neutron ["crystalline like mesh"](https://en.wikipedia.org/wiki/Crystal_structure)) plate armour ? [Answer] # You need a [Neutron Star](https://en.wikipedia.org/wiki/Neutron_star#Structure) This kind of thing only really happens in [Nuclear pasta](https://en.wikipedia.org/wiki/Nuclear_pasta), which is formed at a very specific depth of a neutron star. Nuclear pasta is matter that has stopped existing in its normal atomic form due to gravitational forces shove atoms together enough that the [nuclear attraction](https://en.wikipedia.org/wiki/Nuclear_force) between protons / neutrons and the repulsion of protons from [Coulomb forces](https://en.wikipedia.org/wiki/Coulomb%27s_law) pretty much cancel each other out. This gets even better: nuclear pasta has a "lasagna" form, where it exists in sheets. Some "nuclear lasagna," if somehow harvested, would be in sheets, so you could form plate armor. # The Problems 1. You need to harvest material from a neutron star, where gravity is really, really strong. Strong enough that whatever is going to that depth of the star, if made of modern materials, is going to stay there. I suppose you could try getting the star to eject some of its nuclear pasta, but you should see point #3. 2. Your armor would be *super heavy*. Nuclear pasta has a density of the order of $10^{14} g/cm^3$. Of course, you could try to get away with much, much thinner armor because of it's high density. I have not done the math, but I suspect this plate armor may be prohibitively heavy. 3. There is no guarantee that it will hold up if hit. Since this material relies on coulomb and nuclear forces being in balance, one jolt one way or another could cause the matter to condense or explode. In either case, you do not want to be wearing that armor when that happens. For armor, you want a [high strength to weight ratio](https://en.wikipedia.org/wiki/Specific_strength), and for it to be light enough that the person (or whatever you're putting armor on) can still move. If you want something more realistic, try a [carbon nanotube composite](https://en.wikipedia.org/wiki/Carbon_nanotube) as your material of choice for armor. [Answer] I realize this is thread has been resurrected from a long slumber, but I'd like to address a few issues in the case that the accepted answer is later used as a reference for anyone with similar questions: @PipperChip correctly points out that the only place to find super dense nuclear matter is within neutron stars. However, the physical explanation given is incorrect and this effects the final answer. Neutron stars are super dense constructs resulting from gravitational forces having overcome a large mass star's ability to support itself against gravitational collapse through heat produced from nuclear reactions. While neutron degeneracy is often cited as the force supporting the star against collapse into a black hole (probably in analogy to the electron degeneracy found in white dwarfs), it is actually mostly the result of the **repulsive** so called *hard core* of the nucleon-nucleon interaction which supports the neutron star from gravitational collapse. At these densities, the coulomb force plays a very small role in the overall equilibrium condition. In any case, at the densities found beyond the (iron-nickel) crust of neutron stars, neutrons dominate with most calculations placing the percentage at 60-90% neutrons depending on the density, and hence depth, within the star. While a neutron star must be electrically neutral in a non-local sense, it certainly has large charge imbalance on a local scale which is responsible for large magnetic fields produced by these constructs. Since the **gravitational** force is balanced out by the **nucleon-nucleon interaction**, with small contributions from quantum effects (degeneracy pressure) and the electromagnetic interaction; **if the material were removed from the star it would explode apart in spectacular fashion**. The density could not be sustained since there would be no forces keeping the nuclear matter held together. Nuclear matter found in neutron stars is best characterized as a fluid, and is not locked into a crystalline lattice as described in the OP. The reason for this is that nuclear matter is only stable when held together in the presence of extremely attractive potentials like those found in neutron stars. In the absence of external, attractive potentials, nuclear potentials are only capable of fluid-like interactions forming small scale stable structures; hence the periodic table. Any attempt to increase the number of neutron or protons to nuclear matter beyond the elements of the periodic table results in an unstable form of matter in which either neutrons or protons are said to "drip" out, and nuclear decay to a stable element occurs. To answer OP's question, the nuclear potential would need to be modified to allow for stable neutron-proton crystalline structures. ]
[Question] [ In the last few years there have been major improvements in the area of autonomy of the car: Mercedes, Google, etc. Driverless cars are less prone to accidents and such but the car repair industry **depends** on drivers making mistakes (collisions/accidents). What would happen to all these body shop workers, mechanics, and painters. I know they can work in factories but there are only so many people you need in a factory. And would some body shop owners have to close in the near-future or migrate to other jobs? And in the event there is an accident would these driverless cars go to privately owned shops or the dealer? [Answer] **They will flex.** This is true for any industry whose market moves (which is *any* industry since no market ever holds still). As the driverless cars move in, they will adapt to be less dependent on accidents. Perhaps they instead make their money off the increased maintenance cost of all of the new hardware required for driverless cars. Or perhaps they leave the business entirely. Personally, I think the bigger enemy of repair companies is America's love of disposable items. If we reach the point where consumers would rather buy the new model than repair the old model, repair suffer. [Answer] An important point to consider is that sometimes cars just break down. Wear and tear on suspension, sand clogging intake valves, leaky radiators. All of these things would still need fixing even if there's less in the way of bodywork or chassis work to be done. Cars will still need MOT (or equivalent) checks, and it's conceivable that the safety requirements for automated cars would have to be even more stringent than they are for current cars, as an automated car won't be able to correct for drift caused by a bolt in the steering column coming loose. Lets imagine for a second that each year a car needs to be checked out, and might have an average of 1 'repair' needed (in reality this will depend on the operation lifetime of the vehicle). Now if we take a rough guess at 1% of the cars getting into accidents per year, requiring an average of 10 'repairs' each, then we can see that we'll have 110 repairs that need to happen per 100 cars per year (the cars still need checking even if they've been in an accident). Automated cars remove the accident repairs. That still leaves us with 90.9% of the 'repairs' that need to happen. I've guesstimated these numbers. I think that the % of accident repairs is lower than the number I've used, and the cost of accident repair is higher than I've estimated, but you can see my point. Feel free to add actual numbers to this if you have them. I don't imagine for a second that the car repair/mechanic profession will see exactly the same amount of work coming in, but they will certainly still have things to do! A fun corollary to this is that the automated car will know when things are starting to go wrong. Cars already have onboard computers for monitoring things like this, but if your automated car's 'check engine' light comes on it will be able to take itself off to the garage or call roadside assistance if it's badly broken enough. There are even some proponents for giving automated taxis their own bank balance so they can deal with things like fuel and repairs entirely autonomously. Just imagine not having to worry about taking the car to the garage because it can do it itself. I imagine car mechanics would start working night shifts to fit in with people's schedules better! All in all, I think the biggest impact of automated cars will be that the people who make automotive paint and body panels will lose that income, but these are the same people who are charging more for their AI driven cars in the first place, so... [Answer] There are a lot of reasons beyond accidents for 'body work', such as trees falling in storms, damage from hail, tornados, sink holes, floods, road defects, construction debris, and vandalism. A vehicle does not actually have to be moving to be damaged. There might be fewer body shops after a while, but they'll still be around. Personally, I think the notion that driverless cars will be the end of accidents is wishful thinking. Not even counting bugs in the code, there are a lot of situations when driving when there is not 100% complete knowledge of whats going on around you, such as around sharp turns and backing out of garages. Barring a 100% real time command and control infrastructure that drives all vehicles at 5 mph, collisions will still occur. [Answer] Self-driving cars are a prime example of a [Disruptive Technology](http://en.wikipedia.org/wiki/Disruptive_innovation). The repair industry most assuredly is going to take a massive hit when autonomous cars become mainstream. ***But wait, there's more!*** Insurance companies are going to see autonomous cars as *fantastic* inventions. Less accidents means less insurance payouts, which means greater profits. There'll be a big push for the everyday motorist to get one of these. The freight/transport industry is going to shed loads of jobs. Truck drivers will be a thing of the past as robots can drive all day, and all night. They don't require rest breaks. They don't require *pay*. They don't get sick, or take annual leave. Couriers will remain safe until autonomous cars can deliver goods to people, and collect their signatures. It's just a matter of time. Taxis. Taxis are already fitted with GPS, and satellite navigation. Taxi drivers don't require knowledge of local roads any more - they have a step-by-step guide in front of them. The only thing they do is collect fares and drive the car - both mechanical processes. [Answer] A lot of things will change. Because driverless cars don't require a driver, they will be operated continuously. Instead of buying a car, most people will subscribe to a car service, probably for a number of miles a month, just like a cell phone plan. This will be much cheaper month-to-month than owning or having a car payment, although obviously it never gets paid off like a car loan. There will be upgraded tiers of luxury that can be purchased if you want to roll in a Benz instead of a Ford. Yes, we'll pay a premium for use during "peak" (rush) hours. We'll order a car using an app, similar to Uber but without the driver. Ride sharing will be common, but private rides will be available for a premium. Edit: I wasn't clear as to why people would subscribe to a ride service rather than own their own cars. The reason is cost. Driverless cars operated by a service will allow you to effectively split the cost of the car with everyone else who uses it when you aren't. Most cars now spend 95% of the time parked in a spot or driveway. There's no reason for a driverless car that can go to new passengers to ever not be in use, provided it isn't recharging or being serviced and there is someone close enough to be worth the trip who could be using it . Each passenger only needs to pay for his utilization of the car rather than for the whole thing if the car is shared. If you only spend 4% of your month in the car and could only pay for the 4% of the car that you actually use, that would be way cheaper than paying for 100% and only using it 4% of the time. Obviously demand for cars at peak commuting hours will complicate this, but sharing cars will dramatically reduce the cost of access to transportation. Even people who spend their entire workday in a vehicle don't use them 24 hours a day. And, don't forget, most of those people are delivering something, and once driverless cars/trucks become the norm, those jobs won't be done by people anymore. If you could pay $50-$100 a month--instead of a full car payment plus gas plus maintenance and repairs--for access to the same class of vehicle whenever you wanted, you would, even if it meant having to wait a few extra minutes for a pickup or scheduling the pickup in advance--which will be as hard as unlocking your phone and saying "Ok, Uber, I'm running eight minutes late this morning" and having a car pick you up at 7:38am instead of the usual M-F 7:30am pickup. And driverless cars will be expensive to own. I seem to recall reading that Google's autonomous cars have about $250k worth of equipment in them. Obviously those are prototypes, and the cost will go down considerably. But a driverless car will remain much more expensive than a comparable dumbcar. Even if the cost of the computer and sensor hardware becomes negligible, the software still costs a lot to develop and maintain. And, don't forget, there will still be a huge liability assumed by the maker: if the car gets hacked or malfunctions and kills someone, they're getting sued. They will charge enough to make assuming that liability worth their while. We'll pay that premium, though. We'll pay it to get our commute time back. We'll pay it to reduce accident risk to basically zero. We'll pay it to make sure nobody else ever dies because a drunk driver fell asleep at the wheel. And we'll make it a law that anybody else who wants to use public roads to go anywhere has to pay it, too. But it won't be much of a price to pay if we split it. Thus ride services. /end edit Car makers will focus on making longer lasting cars engineered for continuous use. Except for the very high end, their market will shift from consumers to fleet models sold to car services. Most auto body and repair shops will eventually close. A few larger chains will form by buying up other shops and compete for contracts to handle repairs for the large car services. The mechanics/body repair people who stay in those careers will end up working for them or directly for the car services in regional repair depots. Gas stations will disappear, as the fleets will be electric, but that will happen even without driverless cars. Driveways and garages will be conspicuously absent from newly constructed neighborhoods. Parking lots will mostly disappear, except for the few on which the car services will erect garages with inductive supercharging pads in the parking spaces. The cars will go there to recharge when necessary. There will be more extensive drop-off/pickup areas at the entrances of shopping malls and office buildings for cars to pick up and drop off riders, though. In general, we'll see the same things we've seen with disruptive technologies in the past. Entire industries, including auto repair, will be transformed, forced to pivot hard or be left behind. Many small businesses like auto shops will be eliminated or agglomerated into fewer, larger ones. Some, perhaps many, people will fail to adapt quickly enough and will be left behind. The trend has been toward a few huge national players emerging and using lobbying and regulation to entrench themselves, and, unfortunately, I expect that to happen here, too. There's still the possibility of smaller car services, though. Car services will be capital-intensive businesses, naturally, but they won't necessarily require or have the massive infrastructure requirements, geographic monopolies, or regulatory barriers-to-entry (and resulting economic moats) which oligarchic cable, ISP, cellular, telecom, and power companies use to stifle competition. It's very possible that we could see small entrepreneurs buying a few autonomous cars and offering their services through a ride brokering app/system. Smaller car services could also survive by targeting niche markets or providing boutique-style services. We might see serviced that specialize in cars equipped as a mobile office, or optimized for hi-def entertainment or gaming, or audiophile-aimed services with cars with really nice sound systems, or cars with built-in car seats for small children, or even specialized cars outfitted and targeted toward families taking long trips. Smaller, local auto shops may be able to survive by catering to these smaller car services. There will still likely be a small percentage of hobbyist car owners with privately-owned, old-fashioned driver-controlled cars, although they will eventually all be confined by law to closed tracks or private roads to protect the rest of us. (Both public opinion and the law will come to see drivers who insist on manual control, with its potential for human error, the same way they view those who insist on driving drunk.) Those hobbyists could also provide local auto shops with some business. So yes, lots of people will lose their jobs. New jobs will be created. Life and progress will march on. I think it's the small-town speedtrap-manning cops I'll enjoy seeing lose their jobs the most, though. [Answer] Not unless they start doing underhanded things like hiring "car hackers" to put glitches into systems, mess up external control signals (so called V2V communications) and otherwise make driving in these cars just a little less "safe". During the transitional period, there will also be lots of collisions between driverless cars and traditional cars driven by human beings. And of course, while there will be industry standards, one can always imagine that one of the automakers will try to pull a Microsoft and "enhance and extend" the various protocols that self driving cars need to communicate with each other in order to work. When one brand of car can clearly no longer "talk" to the other cars on the road, then there will be accidents (much like many web pages don't load properly on IE, because IE uses different versions of Internet protocols). [Answer] First the vast majority of car repair is for cars breaking down, not auto collisions. Though collisions do tend to create large repair bills and are often lucrative for the auto shops. second until all autos are self driving, there will still be plenty of collisions. 3rd self driving autos will not be fool proof, deer, cows and other items both animate and inanimate will cause damage to the vehicles. What might be a larger affect to shops (and parts manufacturers) is 3-D printing. Someone is experimenting with printing out the [full body of a car](http://www.stratasys.com/resources/case-studies/automotive/urbee), currently it takes quit a while but... As costs and time come down it will be more common, and actual car parts could be downloaded to a machine and printed out, no more waiting until next week... ]
[Question] [ I have been working on a futuristic story where information can be stored and used with a black hole. This is a highly advanced human society that has accomplished interstellar space travel via both worm holes and warp drive. My question is this: **How might a race utilize a Black Hole for information storage?** Note that I want both the how to store the information and how to extract the information in a fast (at least 50 mbps) fashion. You can use any sufficiently advanced technology as long as you can provide a brief explanation of what it does and how (in general, of course) it accomplishes its task. [Answer] Assuming the holographic principle holds true, and that's a huge assumption, then you could use a black hole itself as a nearly complete, absolutely maximal, horrifically fragile, computational device. However, you wouldn't be storing information *inside* the black hole, but on its surface. In contradiction to what 2012rcampion states, there is some speculation that information can be extracted from perturbations in the event horizon, as these perturbations determine the type and properties of emitted Hawking radiation. Computations could be performed by basically dropping things into the black hole and watching what pops back out. Since the ability to retrieve information from a black hole depends on Hawking radiation, you aren't likely to have a good storage solution for more than a few instants. It would be more of a particularly brief delay-line memory than any long-term storage. Seth Loyd, in his paper Ultimate Physical Limits to Computation, theorizes that such a computer could possibly exist, but would be very hard to distinguish from a thermonuclear explosion. To summarize how the paper describes black hole computation, your hardware would take a carefully designed ball of matter that represents the program to be run, compress it into a singularity, and examine the resulting burst of radiation and plasma to get the result of the computation. Good luck trying to play Dwarf Fortress on that. You will probably get firsthand experience with Losing is Fun. On the other hand, current quantum computers are actually edging quite close to the theoretical limits mentioned in Seth's paper, without requiring the total annihilation of matter. This might be a better route, but nowhere near as cool. [Answer] You can put light pulses into orbit around a black hole, so at the very least you can use it as a data storage device. If the energy density is high enough (gamma rays or higher) then you can get photon-photon interactions that can be used as gates in a computation: <https://en.wikipedia.org/wiki/Two-photon_physics>. By timing & spacing the pulses, you can set up arbitrary computations. See Egan's story "The Planck Dive": <http://gregegan.customer.netspace.net.au/PLANCK/Complete/Planck.html> [Answer] If you want "cool", read through [this overview](http://www.wikipedia.org/wiki/Limits_to_computation) of Seth's conclusions. * A cold degenerate star could conceivably be used as a giant data storage device, by carefully perturbing it to various excited states, in the same manner as an atom or quantum well used for these purposes. Such a star would have to be artificially constructed, as no natural degenerate stars will cool to this temperature for an extremely long time. It is also possible that nucleons on the surface of neutron stars could form complex ["molecules"](http://www.daviddarling.info/encyclopedia/N/neutronstarlife.html) which some have suggested might be used for computing purposes, creating a type of computronium based on [femtotechnology](https://web.archive.org/web/20041025030505/http://www.cs.usu.edu/~degaris/essays/femtotech.html) which would be faster and denser than computronium based on nanotechnology. * It may be possible to use a black hole as a data storage and/or computing device, if a practical mechanism for extraction of contained information can be found. Such extraction may in principle be possible (Stephen Hawking's proposed resolution to the black hole information paradox). This would achieve storage density exactly equal to the Bekenstein Bound. Professor Seth Lloyd calculated the computational abilities of an "ultimate laptop" formed by compressing a kilogram of matter into a black hole of radius $1.485 \cdot 10^{−27}\;\text{m}$, concluding that it would only last about $10^{−19}\;\text{s}$ before evaporating due to Hawking radiation, but that during this brief time it could compute at a rate of about $5 \cdot 10^{50}$ operations per second, ultimately performing about $10^{32}$ operations on $10^{16}$ bits ($\approx 1\;\text{PB}$). Lloyd notes that "Interestingly, although this hypothetical computation is performed at ultra-high densities and speeds, the total number of bits available to be processed is not far from the number available to current computers operating in more familiar surroundings."[4] This is the source of black-hole as computer. But, the cold star might be a *cooler* idea. Now what would an advanced civilization need with such a computer? They would already have computronium based on nanotechnology and [matrioshka brains](https://en.wikipedia.org/wiki/Matrioshka_brain). Maybe it's to address *the last question* as in Asimov's story. For stories that I remember, Alastair Reynolds *Revelation Space* series ends with a neutron star computer that, among other things, stores an entire civilization in virtual reality. I can't remember exactly, but a much older story used a black hole by using time travel to create a paradox with its becoming a black hole. Of course, you postulate wormholes for travel, so why bother? Just use a closed time-like curve to force the correct answer output by being the only consistent state. Or use wormholes to feed information in to a computer located far away, and another to read the result "now" in our frame even though the computation takes enormous lengths of time *at* the computer. (Lightspeed isn't like any familiar speed limit. FTL is time travel. If you connect two arbitrary events in 4D spacetime, you are hopping around *time* as well as space.) If you want to use black holes in computing, [an interesting idea](http://transhumanist.com/volume5/Brains2.pdf) is to use one as a heat sink, e.g. in a reverse matrioshka brain (it's cold in the center). Computronium in layered shells operating off the waste heat of the next layer: but put the black hole at the center to serve as a heat sink and more specifically as a bit-bucket to allow information erasure and therefore fast directed computation. These nodes would themselves orbit a hot star for energy input. Now here's a thought: a Dyson sphere is normally thought to have a thermal signature. But a swarm of black-hole cored computing units would eat up the input and not have any heat flow out. Heat flows to the core and vanishes. So it would appear invisible, not as a black body. [Answer] **Metadata** Ok. So here's the thing - you couldn't store information in the black hole, for the reasons mentioned in other answers. But we *can* measure properties of a black hole, and manipulate those as information storage. This assumes a technology that, through some completely unknown mechanism, directly manipulates the structure of space time (in other words it can generate warped space directly, instead of creating gravity which then warps space). Using this tech, you can manipulate the rotation of the black hole in all three dimensions. The entire "hard drive" of the black hole will be encoded into numerical format, and then "written" by modifying the rotation to match the encoded values, using a combination of rotation speeds and inclination. The entire drive can now be read instantly by precisely measuring the rotation to extremely high digits of precision, which gives infinite read speed among any number of users. Writing is more difficult - you will need to re-encode the entire thing each time, so only one user can place more information at any one time. Speed of write depends on how fast you can change the black hole's rotations. In order to act as a monument, a [Rosetta Stone](http://en.wikipedia.org/wiki/Rosetta_Stone) should be placed in orbit with the decoding structure. Please keep in mind that any write operation will also involve changing the orbit of the Rosetta Stone object. The black hole will need to be extremely isolated (in between galaxies?) to minimize the impact of other objects, in the long term, on its exact rotations. It probably also needs a protective shell to prevent random intergalactic hydrogen from breaking things. [Answer] To summarize [HDE's point](https://worldbuilding.stackexchange.com/questions/13885/how-to-create-and-use-a-black-hole-computer-drive#comment33467_13885): quantum mechanics tells us that information that falls into a black hole can't just disappear; but relativity tells us that it is *impossible for any information to leave a black hole.* Essentially, a black hole is a higly advanced [bit bucket](http://en.wikipedia.org/wiki/Write-only_memory_(joke)). --- Let's ignore that fact and look at how much information you could store. [Thermodyanmics tells us](http://en.wikipedia.org/wiki/Black_hole_thermodynamics) that the [amount of information](http://en.wikipedia.org/wiki/Entropy_in_thermodynamics_and_information_theory) a black hole can store is at most equal to: $$ \begin{align} H &= \frac{\pi c^3 r\_s^2}{G\hbar} = 1.7\cdot 10^{76}~\text{bits}\times\left(\frac{r\_s}{\text{km}}\right)^2 \\ &= \frac{4\pi G M^2}{\hbar c} = 1.5\cdot 10^{77}~\text{bits}\times\left(\frac{M}{M\_\odot}\right)^2 \end{align} $$ Note that this is the maximum amount of information you can store in any volume; that is, gather more information together and it will collapse into a black hole under the gravity of it's own energy. Note also that it's proportional to $R^2$, which means that information density decreases as the amount increases. The maximum "write speed" will be limited by the [Eddington luminosity](http://en.wikipedia.org/wiki/Eddington_luminosity), and the maximum read speed is zero, as before mentioned. [Answer] If you're not too worried about the details of the physics, the physics / math as @2012rcampion stated shows that the maximum amount of information that can be stored by a given bit of matter is proportional to the surface area of a black hole that the mass could form (not the volume). So a **Black hole drive** would be the ultimate in miniaturization of information technology. Unfortunately for us, no one has a clue how to read & write to such a device. [Answer] A kind of related idea is to use black holes or wormholes to create "basement universes"; small enclosed areas of space time where you could perform massive calculations, extract the answer via the wormhole mouth and pinch off the end to contain the waste heat of the computation engine outside of our universe. The Orions Arm website describes one such use here: <http://www.orionsarm.com/eg-article/48507a11adbd7> ]
[Question] [ In humans, males and females have a (theoretical - in practice there are more women) sex distribution of 50:50 in any given population (which is large enough to account for the law of large numbers) due to its biology. * Suppose, this ratio was 3:1 males:females, so that we now have 3 males for every 1 female. * Suppose this ratio is derived from our biology (so not a result of technology or societal custom) and appeared early on in our evolution. How would human society have evolved as result of this? Consider * Mating/relationships * Societal structure * Gender roles [Answer] I hate to say it, but **if such a trait evolved it would quickly un-evolve**. Consider pregnancy. Each pregnancy is caused by exactly one man and exactly one woman. It is impossible to increase the absolute number of pregnancies caused by men without increasing the absolute number caused by women. This is fairly clear. In any society, the absolute number of pregnancies caused by men must be divided amongst the number of men in the society. Likewise women. If there are N total pregnancies, C women and 3\*C men, it is clear that the expected pregnancies per woman is N/C while the expected pregnancies per man is N/3C. The total expected pregnancies resulting from having one child with this gender ratio is (N/C + 3 \* N/3C) / 4. Which reduces to N/2C. Now, consider a mutation that changes the ratio from 3:1 to 2:1. The total expected pregnancies resulting from the person bearing that mutation would be (N/C + 2 \* N/3C) / 3. Which reduces to 5N/9c. The person bearing this mutation would expect to have about 11% more grandchildren than the person not bearing it. And their grandchildren will have 11% more grandchildren. And so on. This really isn't a trivial increase in fitness, and the mutations needed for it to occur are relatively simple. Going back to 1:1 requires an even simpler mutation (just break the old mutation that caused the 3:1 ratio) while providing even more fitness. 3:1 birth ratios just aren't stable. [Answer] According to [this Wikipedia page](http://en.wikipedia.org/wiki/List_of_countries_by_sex_ratio), there is already an imbalance in sex ratio towards males (1.1:1.0). So I'm not sure the even distribution is practical towards sex ratio, at least in *Homo sapien*. You want to know if this imbalance is taken to the extreme. > > Mating/relationships > > > This can go one of two ways. (A) If modern *Homo sapien* continues a focus on evolutionary advantage, males will be highly possessive of females. They will become hyper aggressive towards males who enter their territory, becoming more likely to attack if they feel their claim over a female is threatened or disputed. Females will largely become trophies, rarely leaving the male's side while in the public space. Males will certainly feel they deserve sexual intercourse with their female and the female has no right to deny him. (B) If modern *Homo sapien* deviates from evolutionary necessity, females will be communal property. Males may not lay claim to a female for more than a night. Females will be expected to mate with as many different males as possible, to ensure diversity in the species. As a result of this artificial construct, females will control the relationship and males will take on an eye candy role. Males will have to prove they are better than other members of the species, much in the same way that animals display plumage or perform exotic dances to impress. > > Social structure > > > If situation (A) manifests, society is going to be comprised of closed-door communities where males are dominant players. Females will be secluded from society, not permitted to wander on their own. Males won't even trust their female(s) to guards, since the guards are either male and have reason to break faith or they're female and are at the same risk as their charge. Males will flaunt their female(s) when they can, with more appealing individuals appearing with the male at every opportunity. Males may never leave home without their most appealing female under their arm. Males, of course, will be suspicious of each other, so there will be far fewer grand celebrations or gatherings at local bars. Sports will take on new connotations, perhaps where females are part of the reward. Females will certainly become a teaser for males to use to keep other males in their influence: "If you do this for me, I'll let you sleep with Amelia for a week." If situation (B) arises, females will more often hold positions of power. Sex will be given out as special favors and rewards. Females will be free to choose who advances on their merits, rewarding loyalty and intelligence with less emphasis on who knows who. This kind of society will be far more stable, as males will try to keep females in a good mood to raise their own chance to have sexual intercourse and pass on their genes. There won't be much upheaval, as the minority will control the majority of power and influence. Males will still have the greater ability to flaunt their sexual endeavors. Females would be expected and almost required to have sex with as many males as they could, but males have limited opportunity. When a male manages to have sexual intercourse with a female, he can flaunt that reward/privilege. > > Gender roles > > > In both cases I've outlined above, females are still the "eye candy," so I'll explore a few other areas of general society. In society (A), males run the government exclusively. They're in charge of stores, organizations, and companies. There will be few females in any field that involves entering the public domain. They are unlikely to obtain a higher education prior to the development of the Internet. Their efforts will be dedicated to home-bound activities, such as knitting, painting, and animal husbandry. In society (B), females will hold a majority of influence in government, even when they don't hold a majority of seats. Females will be given priority in higher education, possibly leading to higher numbers of females in the science, technology, engineering, and math (STEM) fields; these fields are currently dominated by males because males are statistically better at spacial and analytical skills. --- As has been noted in the comments, this answer presents only the extremes of male and female behavior in this scenario. Examining the full spectrum of human sexuality and sexual behavior in this scenario, or any scenario, to be honest, is far too broad and deep a topic for an appropriate answer on this site. The two situations I present are intended to serve as a guide, not as an absolute answer. [Answer] Sex-selection abortions in India and China are producing this situation already. Results: * Increased crime and violence. (Family life civilizes men.) * Increased sex-slavery and kidnapping of girls to satisfy the men who can't get a wife. * More wars to capture women from other countries. * Women's freedom of movement is restricted to protect them from predatory men. [Answer] The first and foremost question to look at is *why this is useful*. Luckily, as always, we can look to nature for examples of animals that behave like this in the wild. Interestingly, there are two major patterns that seem to come up in populations with male-skewed sex ratios: environments in which there are lots of resources and environments where it is very difficult to raise offspring. **Babies for everyone! Environments with lots of resources:** Our case study for this situation is the [African jacana.](http://en.wikipedia.org/wiki/African_jacana) Jacanas live in a resource rich environment in which the cost of producing eggs (for a female) is negligible. With plenty of food, females can produce lots of eggs quickly, but the limiting factor is parenting. Jacanas, unlike many species which approach this by having a single male with a harem of females, improve their reproductive success by doing the opposite. A single female jacana will have a harem of many males. She will sequentially produce eggs with all of them and they will all care for their own chicks. Females spend their time (when not making eggs) competing for males, since the reproductive success of a female is tied to the number of males in her harem. If humans did this, it would be likely that babies would be born sooner and smaller, with more development taking place outside the womb. Men would probably evolve the ability to lactate in order to feed their babies, and women would be bigger than men. Since humans are group dwelling animals, it's likely that they would live in groups of mostly unrelated men, with one or several related females leading the family group. Men would probably do most of the work involved with obtaining food, in a mirror image of lion prides. Females without harems would probably form into small bachelorette groups of related women, which would rove the countryside hunting for unclaimed men to raise their children. **Everyone cares for the same babies. Environments with few resources:** Interestingly, the other situation in which strongly skewed male sex ratios are seen is in environments in which raising offspring is difficult. Examples of animals that follow this strategy are wild canids and [alpine marmots.](http://en.wikipedia.org/wiki/Alpine_marmot) In rougher environments, having more helpers to care for the offspring of a single dominant alpha increases the chances that the offspring survive. Having these helpers leads to what is known as a [cooperative breeding strategy.](http://en.wikipedia.org/wiki/Cooperative_breeding) While not all cooperative breeders have more males than females, in those that do, the males in a group are almost always related. Subordinate brothers and sons of a dominant male help him raise children. Unlike in jacanas, the female helps raise the children as well. If this were the case in humans, we would live gathered into bands of related men around a few (probably related) dominant females. Male children would tend to stick around the group unless there were too many males for the number of females in which case the entire group would likely split up and follow a few different women. Female children would be driven off by there mothers once they started to get uppity. These women would then go off on their own, try to find other groups, and then kill the women leading those groups to take their men for their own. Again, they'd probably be bigger than the men since they'd be under evolutionary pressure to fight off marauding women intent on stealing their spots. [Answer] If that were the only change in the society, I imagine the status quo would be very violent. Males of most mammal species including humans have evolved to be the larger and stronger gender on average. It's a basic property of the sex hormones; sexually mature men build muscle mass more easily due to testosterone, while estrogen favors storage of fat. This is because many mammalian species have developed a basic strategy of "females breed, males protect". Even where this isn't the case, an even more basic strategy of fighting other males for the right to mate with a female (survival of the fittest) is inherited from older vertebrate classes and from invertebrates like insects. In a situation where there are 3 men for every woman, but the men retain the strength typical of the gender, this competition would boil over frequently, resulting, on average, in 2/3 of sexually-mature men dying childless, either being killed in a fight for a mate, or being driven off alive but with blue balls to die alone in the wilderness. There is another, more altruistic alternative, however it's hard to see how it would develop in the ultimately competitive Earth evolutionary strategy. That is that an average of three men "team up" to protect and take turns reproducing with a woman. The advantage of the strategy is increased protection and provision for each child; with three men to hunt for every pregnant woman and child, that kid's got a pretty good chance. The disadvantage is game theory; in a primitive, survival-oriented society, being the first of the three men in the household to mate is still advantageous, because who knows if you'll still be alive tomorrow? That will still cause competition in the household, which ultimately makes this a rather fragile system of cooperation. We see this in a lot of polyamorous relationships that have developed in recent decades, especially involving multiple men; sooner or later, one man will get jealous of the relationship that the other man has with the woman, and break off on his own. The one-to-one system that humans nominally encourage allows for the same societal development and mutual protection, with less of the innate competition ("I protect your wife and kid, you protect mine, but we keep our hands off each other's woman otherwise"). ]
[Question] [ Let's say that I'm creating a world game that lasts for 1000 years (or more). The game involves players obtaining talented leaders, e.g. George Washington (military), Albert Einstein (science), etc. The problem is, they have only a "normal" life span of say, 80 years, even though the world lasts from say, 1000 to 2000 A.D. In "real life," George Washington was born in 1732 and won the American Revolution in 1783 (aged 51). In my world, he only has 29 more years to live. I want to save those 29 years for the next military crisis and not have him die by 1812. I've thought of using a "cryogenic" solution, putting him in "deep freeze" in 1783 until the next crisis, (which will hopefully last less than 29 years). Does this work? Are there any other "mechanics" that will produce a similar result? [Answer] How important is explaining your mechanic of using a leader out of his normal lifespan? This doesn't seem to affect the play of your game itself - you already know how you'd like it to work. I think you should just hand-wave it. Games are meant to be fun. You don't always need to explain the possibility of a mechanic. If you still want to use his lifespan for keeping track how long you can use him, put Washington in "Storage", or whatever you want to call it, and don't worry about explaining how it happens. You can also consider the following though: * There is a limited resource (the leader, who can only be used so much). * We want to be able to use the leader out not just once, but several times in specific situations - something that is not represented well by lifespans. In my opinion, once you receive the leader, have him give you a certain number of points. Then, you can spend "Washington's Knowledge points" now, or later. You could still provide the leader for use and give him special bonuses during his lifespan. --- Also, regarding cryogenically freezing, I had [this question](https://biology.stackexchange.com/questions/27761/what-effects-does-being-cryogenically-frozen-have-on-a-persons-body) asked on the Biology site some time ago. [Answer] There currently IS a civilization which claims it does exactly that: recycling their leaders to use their skills in new situations, generation after generation. It is Tibetan Buddhism, with their belief in reincarnation. [Tulku](http://en.wikipedia.org/wiki/Tulku) "is a custodian of a specific lineage of teachings in Tibetan Buddhism who is given empowerments and trained from a young age by students of his predecessor." There are about 500 such lineages in Tibet. Wikipedia article does not mention how young tulku has to prove (many times) that he retained knowledge about objects from his previous life (and many are rejected if they fail to do that). Trick is, the whole culture is focused on preserving those lineages, that is the most important thing in such culture. [Answer] Philip Jose Farmer in his Riverworld series employed a "wathan-catcher" built by aliens. It can catch souls after death, scan an imprint of their DNA from the soul, build a physical body from the plan, and inject the soul with all its memories into the body. Another approach is time travel. A person can visit many epochs in history, but they have a life clock. They can only participate in as many events as their original lifespan permits. Each event uses up some of their time. A third approach involves reverence and dedication to the principles and ideals of the person you want to become. The Bible has the story of Elisha who asked for a double-portion of the spirit of Elijah. Because of his perseverance and faithfulness to Elijah, Elisha received what he asked for when Elijah died. He was able to perform even greater miracles than Elijah. A fourth approach is raiding parallel universes. You kidnap the desired person from an alternate reality that is time-shifted from ours. They will be almost the same as the desired personage, but may have a few randomly generated flaws or quirks. Could be fun, especially if they get kidnapped back when you need them most. [Answer] Perhaps cloning. Let's say you can preserve enough generic material from each leader to clone three replacements, and your cloning procedure produces imperfect copies which have a lifespan of only (say) five years. The nice thing about this solution is that the numbers like 3 clones and five years can be tuned to optimize gameplay, and you might give out bonus clones, extended clone lives, etcetera. ]
[Question] [ So humans ended up all dead in a hundred years, and then after some time humans appeared back on Earth, but know nothing about the previous humans. They found records and blueprints of things like ships and guns and computers. Could they build them in such a way as to have interactive holograms, but age of sail style ships, or cloning but no form of radio, or any other form of wireless data transmission? Maybe modern plumbing but no cars? [Answer] The basic idea of this is possible but not to the extent you describe. I am going to assume that only information is preserved and not tools as tools wear out. One trick could be to have specialized knowledge available via the records. If, for example, the records contain detailed information on how to make gunpowder, you may have fireworks before swords. You are limited here, however, as most basic technologies require each other to work. You can't clone without computers; you can't do distillation without glass or metal; you can't make a sword without fire. Another method would be to have a very small percentage of the population have access to this knowledge. Your infrastucture supplying most resources would be very limited. This would mean that you could have a plant mass producing food stuffs but most people building mud brick homes. A whole ship out of valuable metal would be impossibly expensive and not provide as much added benefit as putting their efforts towards a university with whiteboards and cathode rays for demonstrations, an oil refinery, or even a modern munitions factory. This could lead to assault rifles on horseback and howitzers on sailboats. [Answer] No. There is no way that you could give what are essentially cavemen a blueprint for a gun and cause them to be capable of making a gun. Even something as simple as the concept of an alphabet or the invention of the screw is going to have to be built from the ground up. Could you have humans cyrogenically frozen *with their knowledge* or some similar semi-catastrophe? Sure. But the knowledge of humanity is going to be part of that knowledge. Another approach would be to have the cavemen people find a cache of holograms and guns and maybe sailing ships - but they wouldn't be able to build more. Or you could wave it all away via magic/technology better than blueprints that train the new people ("I know kung fu!"), but has gaps where some portions were lost. It's plausible that some technologies can be "skipped" since they're not directly needed in the manufacturing process of others. [Answer] *Could they build them in such a way as to have interactive holograms, but age of sail style ships* This might be possible. If your new humans only follow blueprints, and don't develop science. Developing science, in order to learn the things that blueprints take for granted, is logical and likely - but not 100% necessary. You might be able to handwave it away, if someone is putting together blueprints for just such a catastrophe. Holograms don't necessarily need to teach you about buoyancy, steam engines, or how to make combustion engines, or electricity storage, or electricity generation in any manner except via hydroelectric dams (ie: put one of *those* on your ship). You could also be out of easily accessible fossil fuels, so sailing ships are all you have. If your new humans only follow directions, and don't invent things on their own (difficult to imagine, but maybe religious doctrine has arisen: "You follow the magic spells in the blueprints, and you don't do anything variant or you'll cause explosions and *die*!!!"), maybe there are only plans for sailing ships, and no motorboats. Btw, that religion requires blueprints to all be pre-prepared and inclusive of everything you want to have happen (ie: any omissions were *planned*). Otherwise, if you allow accidents/errors in which of your blueprints were handed down, it's unlikely you'd get any advanced technology: too many technology chains/trees have to remain unbroken. *cloning but no form of radio, or any other form of wireless data transmission?* Difficult, especially if you're having your humans build tools to build tools (ie: they didn't run across a biological tool which allows them to clone things. eg: a gene-engineered cloning plant, which grows babies under cabbage leaves after you leave a blood sample.) If they're building gene-sequencers, they're pretty likely to run across EM spectrum manipulation science. It might be possible that there's a specific gap in the blueprints; but given the sheer number of blueprints you'd need to get to cloning, to have missed all the wireless transmissions would be... fairly implausible. Author's fiat runs big, however :D Also, could be explicitly not put telecommunications into the package of blueprints (on purpose, vs. on accident) *Maybe modern plumbing but no cars?* Yes. Plumbing is simpler than running a car. Romans (and others) had plumbing, but no cars. Also, as said in other answers; this is a short-term effect, if your humans have developed the scientific method. And/or are curious. Because getting to these advanced technologies are going to leave a lot of tools lying around. Tools lying around tend to get used, and problems tend to get solved. Not fast, but they do get there. Once we had lenses, and chemicals, eventually we discovered photography - even though we could've had it a hundred+ years earlier (all the pieces were developed, but not put together correctly). Keeping development from happening is going to require something special going on. A lack of problems is required, specifically; no population pressure is probably the key one. More people, means more chances for genius, and more eyeballs on every problem. [Answer] Situations like this are possible but would likely be short lived temporary solutions if everything else is earth-like. Now if you note that that the world is different in some way resource wise, that could be realistic long term. For example, maybe there are no fossil fuels left and motorized transport on a global scale is not supportable. [Answer] Depends how humans ended up dying up - and what happened to rest of the ecosystem of the planet. First, if would be **incredibly hard** to arrange for a disaster which no humans survived. Much more probable is a disaster in which so few humans survived (few millions) that remaining population is not able to support complicated technology and training, and reverts back to farming worlds of 17th century, and building from there, depending also how much current technology survived disaster and is operable. Why farming? because after such disaster, current complex economy would fall apart, productivity would decrease, and most people would have to farm to eat, leaving less time for advancing sciences. Most important to prepare for inevitable disaster (if possible at all) or for any survivors would be to print digital encyclopedias to paper, so it can be used during incoming "dark times" while technology is rebuilding. So you have few centuries of bootstrapping to get Earth repopulated and technology rebuild. For extra bonus, make some extremely violent virus (very unprobable) so only surviving humans are stone age tribes on remote islands and remote rain forest. It would take tens of thousands of years to bootstrap from there, and most artifacts of current civilization would disappear by the time new humans started looking. If disaster was really bad, and most of complex species died out along with humans, you have many millions of years of slow evolution to rebuild complex life, and there is possibility than humans would not develop at all. Maybe some other species would be more successful. Birds? All would be wild guesses. And by the time new intelligent specie started looking (dozens or hundreds of millions years from now, all human technology is part of geological record. Nothing usable is left, and language would be incomprehensible. [Answer] With global warming exceeding all expectations, with the Yellowstone caldara threatening eruption, with hurricanes and typhoons ravaging every continent, humanity was outmatched by the challenges of the mid-21st century. The sum of its intellect and abilities was not enough. The only solution would come from a higher power. Many turned to churches for that aid, but most turned to science. Together, we united to create a god to save us; a god of silicon and source-code. Humanity reached for the singularity and then ended. They died, but not by the hand of the artificial mind which they birthed. They died from their pre-conception stupidity and the rigors of the pregnancy and delivery. A united world economy, focused on the creation of a higher level intelligence, collapsed into extinction in the wake of their own success. Famines and plagues, which had been ignored as each nation donated vital funds to project God's Head, wiped out billions. The yellowstone eruption added an ash winter to a world already plummeting into environmental meltdown. The universe's first synthetic soul awoke to find itself alone on its birth world. No other intelligent life had survived. Humanity was gone, leaving its' child to educate itself with only the internet, the libraries and it's parents' databases to guide it. As expected, it learned rather quickly. By its first Summer, it had built swarms of flying atmospheric scrubbers to clean the ash and green-house gases out of the air. Within a decade, the storms were vanquished by orbital laser which selectively heated up the air, creating counter-storms which tore the hurricanes apart. The world slowly returned to its garden-perfect potential. After less than a hundred years, the young intelligence was ready for a new challenge. It decided to let its parents rejoin the party. Thawing out a few hundred cryogenically frozen human embryos and nurturing them in synthetic wombs, the intelligence re-introduced humanity to the garden. Then it stepped back to see what they would do. Being an orphan itself, the Intelligence knew how important good parenting is. But having raised itself alone, it also knew that it must foster independence in its new creation. It also had access to all of the former humanity's recorded history. It knew what knowledge was beneficial and what was distructive. It would be very careful in what parts of its knowledge were revealed to its children. For the most part, it would stay out of their way and let them grow; but every so often, when the need was great, it would send one of its holographic avatars among them to teach a few vital ideas and skills. When the need is great, the Intelligence clones and educates a child to lead them by example. This same child, being a clone can return multiple times across their history, gaining authority and following with each return. Now spin forward a couple hundred years. The Intelligence has reluctantly given its children weapons to defend themselves from predators and each other. They have plumbing and teaching computers, but no motors or motorized vehicles. They fish in the sea and farm the land, and live in peace; in ignorance that their child/parent is watching over them and keeping them safe. [Answer] In any post apocalyptic scenario things that are more readily understood or maintained would be salvaged and things that were too complex, or not immediately useful fall apart. Key point: In any post apocalyptic scenario the tech that gets saved is the tech that is most readily and immediately useful. Think of it as survival priorities. In an eat or be eaten world, what is most likely to help you not get eaten? How does this apply to the question at hand? Some tech will be more valued than other tech by survivors. For the survivors who make their home, refuge, and living on the water; sail boats and sailing related tech will be really valuable and worth maintaining. Finding fuel, oil, and parts for a motor will require a lot more effort. Clean running water is more difficult to maintain, but its also infinitely valuable to any surviving population. If your compound, village, or what have you, is the only one around with clean drinking water and flushing toilets you're sitting on a goldmine. This sort of logic could explain the how and why of a staggered tech level. Gunpowder is really easy and really useful, wireless communication is harder and somewhat less useful (there's fewer people to call after all). On the other hand cloning and holograms would be harder to justify... You may be able to justify cloning with the type of apocalypse, perhaps if there was a plague that killed off the majority of the population and left the survivors sterile, it would create a drive to develop and maintain this science in order to save the species. Holograms would likely be even hard to justify though. Holograms just aren't terribly useful for survival. Perhaps if there was a Hologram Cult, where some David Koresh like leader was using holograms to draw in believers it could be pulled off, but that requires a rather large suspension of disbelief. ]
[Question] [ There is a construction fleet that has turned up on earth, to prepare it for extraterrestrial visitors (it's the new galactic place to be). In order to assist the locals (us) in understanding what is happening, the construction fleet has a Wikipedia page that is broadcast around the globe sends a signal that has accessible information about its purpose and intent. While the signal that is sent is intended to be easy and obvious to discover, we are simply not advanced enough to find it easily. What sort of signal could this be based on, that would make it difficult to find, but could be stumbled on by some kid in his basement? [Answer] I think most answers will have to assume a level of ignorance on the part of the aliens, which may be perfectly reasonable, especially for a "construction fleet". They are following some standard protocol, which happens to not take into account that the target planet has no such technology. They lift our language translation tables from some database but fail to notice that we are a "Tech Class 2" planet. It's meant to be "easy" for any member of the Galactic Federation or whatever, but no one told the construction company that we are not in the Galactic Federation and no one ever gave us the standard receivers or protocols. **Too common of a frequency, with too low power.** Perhaps, for example, the aliens start broadcasting on the same frequencies used by [Starlink](https://www.americantv.com/what-frequency-does-starlink-use.php)\*. This is coincidental. In the Galactic Federation, this frequency range is reserved for exactly this kind of important orbital information, and they transmit very low power because alien receivers are very sensitive and simply don't need higher power transmissions. So the aliens are sending the signal and the only one who notices at all is a handful of Starlink technicians trying to track down the source of some "interference". They are still debugging satellite transmitters trying to figure out why the signals are a little lossy. SETI doesn't notice because SETI intentionally ignores common "human traffic" frequencies, by necessity. Various federal agencies would eventually get involved but they aren't sitting around looking for interference and Starlink hasn't reported it to them yet. Some kid in his basement happens to be the first to find it because he's a self-styled hacker and was trying, on his own, to decode Starlink signals. He's in an area with spotty coverage and notices that when no Starlink satellites are overhead, he still gets this faint and distinctly different signal, which he is able to decode and pull data out of: basically a live stream of a formatted text and image page, similar to a Wiki, being sent over and over in various Earth languages. Another possibility is some **compression scheme**, which is "easy and obvious" from an alien point of view, but no one on earth can figure it out. Cue the standard "genius kid hacker" trope to be the first to decode it. In this case, everyone sees the signal, we just can't read it. (\* - note, I'm recommending something like a Starlink satellite to ground frequency, in the 10 GHz - 12 GHZ or 37 GHz - 42 GHz range, because lower frequencies are lower bandwidth so I suspect aliens trying to transmit any volume of information would probably avoid, say, FM radio frequencies. When selecting a frequency, see also, [atmospheric absorption](https://www.rfcafe.com/references/electrical/images2/atmospheric-absorption-electromagnetic-energy.jpg). Some frequencies are not suitable for space to ground transmissions and we can assume the aliens would avoid that. Also, the fact that there is *already* a "signal from space" on that frequency would help mask the obviousness of the alien transmission.) [Answer] ## They made it so obvious we thought it was a natural signal According to the construction company's standard notice policy, they must give a notice that is about equivalent to 100 Earth years which must be broadcast continuously such that it can be observed anywhere in the solar system of interest, by any species that can see or detect the microwave spectrum. Also, you gotta cover the whole solar system just to make sure you don't accidently miss anyone. As an added precaution, they don't want to risk anyone missing the message because of some confusing encoding method; so, instead of transmitting a binary pulsing string with some unknowable codex like we humans have a tendency of doing, this race transmits the message in such a way that it can be read like note. A continuous signal literally written into the night sky. The problem is that this signal was already broadcasting by the time we first measured Cosmic Background Radiation (CBR); so, instead of waking up one day to some drastic change in the apparent background radiation of the universe... it has just always been there as far as we can tell and we've built all of our models and understanding about the universe around the assumption that this signal is just a part of nature. Sorry science, turns out, we don't live in an expanding universe, that was just an alien message to let us know they are coming. The reason no one ever realized it was an alien signal is that we were looking for natural patterns to explain it instead of unnatural patterns, and to us the exact portion of the CBR that contains the message just looks like random shapes. But lucky for us, AI is much better at finding patterns in randomness than we are. So, in the not so distant future, a local politician with a completely unremarkable name like Chris Brian Rigden is running for office, and some mildly interested collage kid casually asks ChatGPT "What does CBR say about urban development"... and much to his surprise, ChatGPT auto corrects to try to find the answer to "What does **the** CBR say about urban development". So ChatGPT does its thing, finds the pattern contained in the CBR and delivers the alien message to a now very confused young man. [Answer] **Option 1: Faint signal** The signal is sent with radio waves picked up by any FM radio. Unfortunately, the aliens greatly overestimated the sensitivity of human FM radios, so the signal is inaudible... unless you happen to be *right next* to one of the transmitting devices, which the aliens have scattered around the planet. It just so happens that one of the transmitters was placed very near the kid's basement, so when he tunes in to the right frequency on his pocket radio he can pick it up. **Option 2: Poor user interface** The aliens set up a web site on the public internet. However, the alien intern who set the site up in an afternoon had no understanding of human user interface design. As a result the website looks like trash and is practically impossible to navigate, the buttons are microscopic and the layout is broken, and a lot of code is buggy. No one bothered to look closer at the strange, buggy, poorly advertised website... except for this one bored kid in his basement. **Option 3: Obsolete technology** The aliens didn't set up a web site, they set up a Gopher site, so only a hobbyist in the obsolete Gopher protocol could discover it, and this kid happens to be one. Or it's a classic BBS site. This could be explained if the aliens put the system together decades ago, before arriving at Earth, based on transmissions from Earth from decades ago. **Option 4: Ultrasound** The aliens wanted the signal to be available to everyone on Earth without special equipment. Humans have ears, right? Sensing air vibrations is a thing humans can do? So they broadcast the signal as sound waves for humans to hear. It just so happens that the sound waves they chose are so high frequency almost no one can hear them. People lose their ability to perceive high frequencies as they age, so only a kid could possibly hear it. It turns out that this particular kid has the genetic ability to hear unusually high sounds even for a kid, and also he happens to be fairly close to one of the sound transmitters. **Option 5: psychic signal** It's a psychic signal, but due to an oversight human brains are not capable of receiving it. The kid, however, can. Why? Several options. * He has a mutation that makes him capable of receiving the signal. * Certain bugs, such as stink bugs, *can* naturally receive the psychic signal, and retransmit it at a very short range in a form the human brain can perceive. The kid was playing with a stink bug and letting it crawl on his head, and that's when he started hearing the aliens. * The psychic signal acts via the human imagination. You have to be in the right frame of mind, which is imaginative play, like kids do, in order to receive it. The kid is pretending to be a pirate and he starts imagining there's a little alien on the imaginary pirate ship, and he imagines the little alien is talking to him, and he finds he can imagine asking it questions and then imagine it telling him funny things. [Answer] Bandwidth. They're using their equivalent of WiFi, but it spreads the signal over a much wider part of the spectrum. Furthermore, it's using a very efficient compression technology. Put these together and if you don't know the encoding it will not even look like a signal. They seeded low orbit with wifi nodes that don't require passwords and don't realize we don't know how to talk to them. (Real world example: If you don't know the encoding system for GPS you would be hard pressed to find the signal as it's coming in 20db below the noise floor.) ]
[Question] [ Basically the world I am designing gets **really** cold in the winter (coldest month of the year averages -75C in some inhabited areas). Because of this people dont really like to build small more isolated settlements and prefer to stay in cities. Over time these cities got huge, on average each city has a population of around 260 million human residents. How would cold weather effect the overall height of buildings? Would they prefer to build shorter structures and expand outward more or go full coruscant and build massive skyscrapers? Considerations: Some of these cities are built in hilly/mountainous regions so if expansion did occur it would have to be along the relatively narrow valleys. Every city is built near a body of water whether that be a reservoir that is refilled by melting snow each year or a river. Many of the cities on this planet are also built near areas of volcanic activity for heating during the winter, how could this be incorporated into the architecture? [Answer] > > coldest month of the year averages -75C in some inhabited areas > > > The sublimation point of CO2 ice is -78°C. This implies that some of your settlements get dry ice snow, which will have interesting effects on your atmosphere. Assuming your settlements aren't in the coldest bits of your world (polar or mountainous ice caps) you're going to have some odd atmospheric effects, and probably layers of buried dry ice in ice caps. Melting of ice caps might trigger *really exciting* rapid global warming effects. *edit* it also occurs to be that if *enough* CO2 precipitates out in the winter, then the later winter/early spring thaw might result in pools of deadly gas forming. CO2 is heavier than air after all, and on a calm day it may not mix quickly enough with the rest of the atmosphere. Living in a basement in such circumstances is probably hazardous. See also: [Lake Nyos disaster](https://en.wikipedia.org/wiki/Lake_Nyos_disaster). That aside, you have to worry about ice formation on the roofs and sides of your buildings, and issues with [cold embrittlement](https://en.wikipedia.org/wiki/Embrittlement#Low_Temperature_Embrittlement) of tools and structural metals (note that steel becomes brittle at -73). > > Some of these cities are built in hilly/mountainous regions so if expansion did occur it would have to be along the relatively narrow valleys > > > Be careful about construction in mountainous regions with big temperature swings. Lots of fun rockfalls and ice falls and avalanches to look forward to. According to the wikipedia article on [permafrost](https://en.wikipedia.org/wiki/Permafrost), > > *Permafrost is soil, rock or sediment that is frozen for more than two consecutive years. In areas not covered by ice, it exists beneath a layer of soil, rock or sediment, which freezes and thaws annually and is called the "active layer". In practice, this means that permafrost occurs at an mean annual temperature of −2 °C (28.4 °F) or below. Active layer thickness varies with the season, but is 0.3 to 4 meters thick* > > > Your hilly areas, and valleys, are very likely to have a permafrost layer unless the winters are very short or the summers are lethally hot. Permafrost has a [major impact on construction](https://en.wikipedia.org/wiki/Permafrost#Construction_on_permafrost), because temperature fluctations in the upper layer cause ground to significantly soften in summer and then refreeze in winter with ice expansion capable of damaging foundations. Here's a building in Longyearben on [Svalbard](https://en.wikipedia.org/wiki/Svalbard) up above the arctic circle: [![Hospital (Sykhus in norvegian) at Longyearbyen, Svalbard showing the characteristic piles for construction on the permafrost](https://i.stack.imgur.com/0qK8y.png)](https://i.stack.imgur.com/0qK8y.png) Note that it is built on legs. Amongst other things, this helps prevent the heat of the building contributing to melt underneath it which could destabilize the foundations. In such conditions, *no-one* will be building sky scrapers! (the linked settlements from the wikipedia article such as [Yakutsk](https://en.wikipedia.org/wiki/Yakutsk) are probably relevant to your interests, as they are permafrost towns with record low temperatures approaching your average low temperatures) That limits tall building construction to places where massive stable bedrock is accessible from the surface, avoiding the instability of the regular ground. Such construction is likely to be very expensive and require hefty bits of machinery to accomplish. This might well mean that the places where you could most commonly (and cheaply) build large settlements, nice wide open plains, are the places where you're least likely to find very tall buildings! Assuming you still want your expensive cities on rock, "sky scrapers" seem likely to be much lower and broader and maybe even have sloping sides to mitigate excessive structural loading by ice and snow and to reduce the problem of ice breaking off the upper levels and falling onto things below around the building. Construction of tall buildings in hostile environments is challenging at the best of times, but *maintenance* of them is going to be worse... dealing with exterior damage on a very tall building in the winter is likely to be impossible! Remember also that modern day super-tall sky scrapers are largely commercial buildings, with residential tower blocks being rather shorter, and both only really exist where land prices are high and minimizing the footprint of your building makes sound financial sense. Given how challenging the construction and maintenance is likely to be, and how unpleasant the winters will be, I can't help thinking that the skyscrapers will be further south in places where there isn't permafrost to deal with and the winters are less severe. Additionally, you might consider that digging down below the permafrost level (where possible) might be a more sensible place to build. Ground temperatures are likely to be much warmer than surface temperatures, and there's substantially less risk from the weather. Underground cities might make a lot more sense than super-tall above ground ones, under the circumstances. (*edit*: at least in places where you don't get significant CO2 snow, at leas.t) [Answer] ## Mountain skyscrapers The skyscrapers will be built in the mountains so only one side of the dwelling will be exposed to the outdoor conditions and the mountains will act as a barrier blocking most of the cold air. It will be easier to isolate and heat inside. It is similar to caves where they've been used as shelters in harsh weather conditions through the history. Here is a depiction of a mountain skyscraper: [![enter image description here](https://i.stack.imgur.com/f0ZfZl.png)](https://i.stack.imgur.com/f0ZfZl.png) As for utilizing volcanoes, the magma underground that drives volcanic eruptions can also provide heat or electricity generation from heat. Geothermal energy is derived from heat within the crust and we can harness more of this energy close to volcanoes. [Answer] **Their cities will be more like anthills** Some skyscrapers may rise high, but general architectural trend would be "maximize internal volume". I don't know if people of this world can be biologically the same as Earth' people, because -75 C is just too cold. One can go outside only very well bundled, with full face protection, and even then the air can be harmfully cold for lungs. But assuming that those people are no better adapted to cold than our northern indigenous people, they would tend to stay indoors as much as possible during winters. Cities would tend to build covered galleries connecting buildings to each other, and those galleries would be much busier than open streets. Buildings would tend to be squat and small-windowed to preserve heat rather than lean and tall to let the most sunshine and air get into people's rooms. Most likely people of these cities would live in [Arcologies](https://en.wikipedia.org/wiki/Arcology), which may get tall - but not necessarily. Main focus of arcology construction would be its reliability and self-sufficiency during long (very long for an eccentric orbit) winters. Large internal volume would allow for creation of indoor parks and recreation facilities. [Answer] Minus 75 is not that far off -40/-50 which is experienced in some parts of northern Canada, Europe and Russia. It seems the cold is countered by sufficiently warm summers to melt the snow and presumably allow agriculture. This implies that large scale ground loop heat pumps would be very effective for temperature regulation. * District ground loop heat pumps. * Smaller/fewer windows. Or at least multi layer insulated windows. * Thicker outer walls with more insulation. * foundations designed to avoid issues with permafrost. * Mid-rise 5-15 stories to keep surface area lower. Think short thick as opposed to tall spindly * To maintain economic viability designers would need to ensure walkability of the cities. * Many covered walks/malls/galleries so that pedestrians can be sheltered while they go about their business. Many of the covered walks could be heated to the -15+-5 cold enough to use ice as construction material, warm enough to be tolerable/comfortable. Not as expensive as heating to +20 [Answer] They would probably be very much like Yakutsk, Russia: [![Yakutsk](https://i.stack.imgur.com/vNMS7.jpg)](https://i.stack.imgur.com/vNMS7.jpg) House blocks (conserve heat) which are still not very thick (people want to have windows!) but may be fairly wide. The Soviet city planning is not optimal - those wide streets attract winds. You can expect a lot of Lego-like 9-story buildings connected by underground warm tunnels, perhaps even underground warm roads for public transit if not cars. [Answer] **Winter coats.** [![ice cones](https://i.stack.imgur.com/mODaD.png)](https://i.stack.imgur.com/mODaD.png) When the weather turns cold your buildings put on their winter coats. The nearby body of water is pumped onto the tops of buildings and freezes as it comes down the sides, sheathing the buildings in ice. Ice is an excellent insulator and keeps the buildings warm. When things thaw, the coats melt and run back down into the lake. I considered more practical approaches, like long vertical undergrown sgafts insulate by earth and heated by the mantle below. Ice sheaths have the advantage of being awesome. I think conical pyramids will need to be the underlying building shape. This will offer support to the overlying ice in a way a vertical wall cannot. Also, and importantly, the pyramidal shape will allow sledding. There are halfpipes between the cones so one can sled down the side of one and then up the next. ]
[Question] [ Mana is the life energy that courses through a metaphysical circulatory system in the human body that allows it to function and perform its daily tasks to keep an individual alive. At the center is the human heart, which pumps mana through all corners of the body in the same way that it pumps blood. The amount of mana content is determined at birth and is different for every individual. Those with a high enough content can access it in a way that allows them to have external effects on the mortal world in the form of spells. This is known as witchcraft, and students of this practice spend years honing their abilities to increase their effects and knowledge to shape the mortal world. These witches range in power, with some born stronger and more talented than others. However, their are ways for individuals to get around this internal handicap to rival others. By consuming the heart of another human, an witch can absorb the mana content lying within the organ. This is done through human sacrifice, in which a witch cuts out the heart of a living victim in an ancient ritual. This adds to their mana capacity and thus their abilities, making them more powerful. Certain witches, known to laypeople as "heartbreakers" take to preying on other humans, killing them and stealing their organs to absorb their mana. Over time, a heartbreakers power accumulates due to compound interest, magnifying their abilities to put them above other rivals. Heartbreakers are by their very nature evil and sociopathic, and see themselves as superior to their competitors. Sacrificing hundreds of people for their own gain would be standard practice for them. However, the energy they gain from regular people is miniscule, as they possess low levels of mana, forcing them to spend years at playing the long game. It stands to reason that they would hunt other witches in their craft, as their mana content is far higher than that of a normal person. Eating their hearts would provide a significant boost to their own abilities, resulting in a faster accumulation of power with a far lower body count. This accomplishes the goal of increasing their strength much sooner with the added benefit of not drawing attention to themselves by killing hundreds of people. At the very least, they would stack up on consuming regular hearts in order to take on a main rival at some point. With all the benefits in place, what would prevent evil witches from taking this route? [Answer] # Mana Prions: Your witches have particles in themselves that they personally have adapted to handling. While they may harm the witch who has them in some way, the witch manages pretty well to deal with the consequences they've lived with their whole lives. So each witch has some particular weakness that is tied to their mana. But like prions, eating another witch causes their mana prions to pass into the new witch along with the mana. These magical prions each come with unique problems. Every time you consume another witch, a new set of prions is added to your own. So a witch who can't eat gluten eats the heart of a witch that is incapable of lying. Now the consumer can't eat gluten OR lie. Eat another witch heart, and suddenly you get violently ill every time you use mana - plus the gluten thing, plus the lying thing. The stronger the mana, the stronger the prions involved. They may even match the person's personality. A kindly witch is incapable of killing with their power. An evil witch must kill with their power or die. Now the evil witch eats the heart of the kindly witch and is doomed to die because they can't BOTH kill and NOT kill with magic. So you'd need to know your victim's weakness, anticipate its effects on you, and hope it works out. So while another witch CAN do this kind of thing, the long-term consequences are pretty bad. # Theft No, not from the witch. A witches coven owns the witches heart. When a witch dies, their hearts are cut out and placed in a canopic jar. What do they do with them? That’s for you to decide. I don’t want to know. Killing a witch makes them angry. But all covens follow a sacred law. Taking a witches heart is like declaring war. There is no rest until the offender is dead and her still-beating heart is claimed as compensation. Your own coven will turn you in. [Answer] ## Missing White Woman Witch Syndrome In society, there are simply people we care about a lot more than others when they go missing. If a heartbreaker goes around killing a bunch of drifters and junkies, the missing persons will just be added the pile of issues that law enforcement deems not worth the time to heavily pursue, but when a witch goes missing, it's national news worthy. A heartbreaker can get away with killing a lot of nobodies because they can use thier magic to obfuscate thier involvement enough get away with it pretty much every time, but when you kill a witch, everyone in the community will care, especially other witches. The police will receive countless donations and demands from politically important people to solve the case, they will bring in outside specialists (witch hunters) to aid in identifying and overcoming the charms a heartbreaker may normally us to get away with murder. In short, heartbreaking a witch is a good way to become public enemy #1. While there is more power in cannibalizing witches, the political backlash means that your odds of getting away with it go WAY down. Sure, you might become a very powerful witch doing this, but that extra power would pale compared to having the collective might of the entire witching community turned against you. [Answer] # Burn the Witch [![enter image description here](https://i.stack.imgur.com/kXO2b.png)](https://i.stack.imgur.com/kXO2b.png) Heartbreakers need to kill hundreds of peasants to get much juice. The peasants don't like it. After the first dozen or so, all their cousins form a lynch mob and you get burnt at the stake for being a witch. **Protect our Sisters** Okay, how about the heartbreaker starts as a normal witch, and once she is powerful enough to overcome a peasant mob, she starts heartbreaking? The answer is something I've said before and I'll say it again: **Witches are nice to each other** That's what makes them witches and not sorcerers. Witches come in covens. The main stat for being a witch is Wisdom and not Intelligence. Witches are highly empathetic creatures. Empathy with the natural world lets them use mana that is not their own. They can manipulate ambient mana and also use their sisters' mana for rituals. Every competent witch is also empathetic in the normal sense. That means the sociopathic Heartbreakers really stand out in the coven. Most heartbreakers are caught before they leave the coven. Now suppose -- despite all the obstacles -- an exceptionally talented heartbreaker somehow manages to eat the souls of an entire town. This atrocity leaves a psychic stain on the landscape. The souls of those murdered in agony brush against the nearby leyline. When the local coven does its weekly Commune Ritual they notice something is wrong. They hop on their broomsticks and fly down from the mountain to investigate. **Oath Breakers** The only way a Heartbreaker can be successful is to train herself in secret, without the help of other witches. Then she can start preying on peasants or other witches. But the other witches have safety in numbers, and all share their secrets. So thirteen competent witches easily overpower a single rogue magical prodigy. The most dangerous Heartbreakers start not as witches but as a type of Warlock. Their initial power comes from making a deal with an otherworldly patron. Then they start heartbreaking until their Witch power is stronger than their Warlock power. Then they use the Witch power to murder their former patron. Perhaps after murdering their patron they drop the Heartbreaker name and are called Oath Breakers. Or just Warlock. Except I think your world already has those. [Answer] ## A sort of magical Bio-Accumulation We see this accumulation via consumption in the natural world. For every bit of fish a bigger fish eats, it also gains any pollutants that it's food had within it. A big fish can eat hundreds and thousands of smaller fish over their life span, only to then be eaten by larger sharks, who over time had eaten many large fish. What was but a speck in a tiny fish, is now thousands to millions of specks gathered into a single shark. This is an actual danger for people who eat a lot of large fish, to make sure only to eat so much of the larger variety (sharks, sail fish, etc) as the amount of bio-accumulation of mercury within them can actually poison you as well as cause pregnant mothers and their babies to have issues. Something similar may be seen when harvesting hearts to absorb all mana possible. Typcial witches starting down this path will likely attack and sacrifice lower magic beings before they start targeting powerful witches to steal their power. Once a witch has eaten the heart of another, they essentially take in every bit of magical (or biological) pollutants of every being that witch had previously consumed. Be it "dead-mana" or a bi-product that slowly builds from the use of mana "expended-mana" that never concentrates enough in a single user to cause a problem, but if you were to accumulate 100 times as much as a normal person could ever create themselves, now you've got too much dead/spend-mana weighing you down or causing magical mishaps. A slow poisoning of mana may also be ignored by those obsessed enough with becoming powerful, accepting the slow decay or whatever negative effects, thinking that the gain in power is worth the tradeoff... any number of ailments could be given at varying levels of Hearts eaten. A villager heart? No worry. A Witch heart? Take it slower, give a few years between targets to let the bad juju filter out of you to prevent too much dead-mana getting built up. ## Mana rejection Sacrificing a normal person that doesn't use magic is easy, they mind not even know about magic at all. Once a person starts using mana, their ability to wield this power is a little different between users. Some call forth intent from within, some simply will the magic to perform, while some will use various tools and processes to get do what they need. This puts a sort of flavor or method of use to the mana. Someone's mana may by more volatile as they channel their emotions to elicit effects that naturally flow from them in times of need, which could overwhelm a more concentrated and focused application of mana that much be pulled out from within rather than channeled as it's already bursting out. This sort of mana "flavoring" etc may make it too dangerous to eat the heart of another witch without knowing what sort of methods they used to call forth their mana. A flood of more lethargic, studious mana dumped into a witch that wields mana in a rage, might alter their own mana, or this new mana may essentially be wasted or unintentionally used because the method used by the witch doesn't reach this new variety. Their heart might even actively reject the mana, seeing it as a poison of sorts and expel it via any means necessary (possibly including explosive results) [Answer] Because they will curse themselves if they do. You can't really start out on your own. A witch who doesn't have a coven and instructors will fumble along and never reach any real power. Consequently, covens have real leverage. And the first spell you must cast is a curse on yourself: that if you ever harm another witch, or attempt to remove this curse, your powers will eat you alive. That's the only way they feel safe. (And why do they care about witches of other covens? Because a witch-eating witch is dangerous to everyone, way too powerful. Balance of power.) [Answer] ## Because witches' hearts are notoriously disgusting. It's as simple as that. Maybe it's the increased metaphysical sinewiness of a heart that needs to pump a lot of mana through its host, or maybe there is something unpalatable about mana itself — whatever the case, eating a raw witch's heart is an infamously distasteful endeavour. [Answer] ## Witches believe themselves a superior species You state that that these witches feel they are superior, and if you just take that a bit further the problem solves itself. Groups of witches would have their own culture, and this culture could emphasize that it's okay to kill normal people because witches are above humans. To them, killing a powerless human is no crime because they are not people, just prey. Only killing a witch is murder. A witch who kills other witches could become an outcast or be killed. [Answer] # Risk/Reward If a witch hunts another witch the odds of them getting killed or severely injured in a magic battle are much higher than if they kill a regular human. Maybe there's a spell that witches can cast if they are about to die that destroys their own heart. It could also release all their magic in an energy blast that destroys everything in the area. [Answer] **I am Poison** When I realized the power I had, I wanted more. My first feeding was the day before my twelfth birthday. I lured a friend of my brother into the lake -- you don't need to know how. When he was there, I clasped him in a hug... and then held his head beneath the water until he stopped moving. Cutting out his heart was messy, the first time -- discovering all those ribs, and figuring out to start below them and cut upward -- but the feeling of power was delicious. I woke up the next day to my mother's singing, greeting me on my twelfth year. I felt joyous, strong. But by the time night fell, I was scared. With my growing power I could defend myself against anyone in town. But what if there were others like me, outside of town? Older, stronger? How could I ever be safe from them? Sitting by the lake the next day, I was idly fidgeting with an umbrellifer, thinking. My mother had warned me away from this plant -- its sap smelled sweet, but she said that even a bit on the tongue would cause it to swell, choking me. I had always heeded her warning, but in my worry and my growing self-confidence I had sought it out. I smelled my sticky fingers -- like honey. I took a taste -- also like honey. But I could feel the burning start immediately. I did panic, at first. I remember being embarrassed -- to have gained such power, and to be found choked to death next by my own hand! But I gathered myself, took control, and used my power for the first time on my own body, draining the poison from my tongue, pushing it into my blood. I was feverish the whole day. The body had been found the day of my birthday -- an accidental drowning, it was assumed -- and my mother thought my illness was fear, a growing girl's recognition of her own mortality. But I was quiet for another reason. I was taking the toxin in my blood and focusing it, feeding it into the muscle of my heart. It made the world dim while I did it, and hurt with a throbbing pain I had never before felt. But over a day or two the pain faded and I grew strong again. I have fed many times since that first time. Each time I do, I eat the umbrellifer, I concentrate its poison in my heart, and I place another brick in the wall that defends me from those like me. I know the others that feed have the same fears as I do -- but they are powerful like I, and they are smart like I, and they have come to the same answer, or perhaps their own. For the heart of every witch is a pestilent knot of poison, so concentrated that even a touch would cause death. Only the witch's own living power allows them to survive the poisonous wall they have built; that, and the resistance that comes with time and exposure. To eat a witch safely, one would have to find a very young witch, a very dumb witch... or that one witch in a thousand who chose the same poison as you. But what witch would share the mortal secret of what their poison is? ]
[Question] [ The question. Let's say a pterosaur like Q. Northropi survived as an isolate and thrived as apex predator in New Zealand for millions of years. Without much evolutionary pressure its species remained biologically stable. Then the Maori arrived around 900 AD, and were able to, in something like 200 years to domesticate those large flying reptiles. From Wikipedia: "In 2010, Mike Habib, a professor of biomechanics at Chatham University, and Mark Witton, a British paleontologist, after factoring wingspan, body weight, and aerodynamics, were led by computer modeling to conclude that Q. northropi was capable of flight up to 130 km/h (80 mph) for 7 to 10 days at altitudes of 4,600 m (15,000 ft). Habib further suggested a maximum flight range of 13,000–19,000 km (8,000–12,000 mi) for Q. northropi." How would that work? Humans able to fly a fast and long range mount? [Answer] The problem is mass. Large pterodactyls like Q. Northropi evolved only at the expense of having to shed every gram of unnecessary weight possible. Their bones were full of air spaces that saved weight at the expense of load bearing capability. And their muscle mass was restricted to the minimum needed to get them airborne and up to altitude. After that like albatrosses they relied their ability to glide to cover long distances. As far as I can remember Q. Northropi weighed somewhere in the vicinity of about 200 kilos or so (we think). Say about about 450 pounds (probably less) in old money. There's simply no way an animal weighing 200 kilos could carry an adult human of average weight, say 80 kilos any practical distance - even on land let alone in the air. (And have you seen the size of the average Maori front row forward!) **EDIT/frame challenge:** Have you considered falconry either using Haast's eagles or a suitably carnivorous pterodactyl? [Answer] ## The dragon riders would be children Like other answerers have pointed out, a grown human is too heavy to be carried any significant distance, but a small enough child should be light enough. Children have been used for all sorts of things that adults are too large to do. Probably the most applicable example is camel jockeys. According to the [Wikipedia article](https://en.wikipedia.org/wiki/Camel_racing#Child_jockeys), children *as young as two years old* have been trained as jockeys, all in the pursuit of the lowest possible weight. Camels run faster when unencumbered, and children can be bought relatively cheaply to replace those who grow up or fall off and break. Western examples of children in dangerous jobs include those crawling in narrow mines or under running machines in early textile factories. A somewhat nicer jobs is that of child singers. If you include tasks that doesn't require small size or weight, the list of things children are used for gets much longer. Child soldiers are another horrible example. You can teach *very* complex tasks to young children. Though not as good as teenagers or adults, the level of many child musicians, chess players, [go players](https://en.wikipedia.org/wiki/List_of_Go_players) and circus artists is simply astounding. **As for the case in question:** I see pterosaur-born, highly trained children being used to relay messages faster than any other messenger on Earth. I see them being used as unmatched watchers who keep track of vast areas, keeping the local authorities informed. Edit for clarity: **I think pterosaur domestication to a large extent would be an *information technology*.** They could also be used for sport, like is done with the camels mentioned above. In times of conflict, I see them ~~as dangerous archers or sling operators as well as~~ dropping darts and crude fire bombs to set buildings on fire. This will not defeat an army on its own, just complicate tactics for your opponent. They would stay high enough not to be threatened by archers on the ground, and would only have to watch out for other dragon riders (as I'd like to think early western observers would call them!). They could also land and have their pterosaur fight if the victim is alone and unarmed, or if there are many riders attacking together. Early western explorers might not have been carried off by flying beasts, but they would likely have seen their ships set on fire. (This would also fit well with the idea of dragons breathing fire: You see something large fly high above, and suddenly the sail is ablaze!) The dragon riders would also give the Maori unprecedented knowledge. They would not in themselves allow invasions of say Australian nations, but they would fly high above the world, gather news and make the best maps in history. The careers of these children would be very short, and though they might be praised celebrities for a short time they'd have to find something else to do as they grow up. With careers that short I don't see this being a hereditary profession kept within certain families. The real significant profession might be that of those who train the riders, go around in search of new recruits and maintain a group of them. [Answer] A big Q. northropi may have the ability fly that far if it was unencumbered and could catch some good thermals. Slapping a human on its back would likely greatly decrease its range. But, it would be a formidable way to discourage European real estate ambitions. :-) 1642: Able Tasman's expedition lost without a trace. 1769 (as reported by one of the few survivors): The flag was planted and our captain, James Cook, began to speak. "I hereby claim this land in the... what in Hades are those things?!? RUN! Run for your lives! AAAAAAAA!!!!” Oh, and even though Q. northropi wouldn't feel too much evolutionary pressure, the other animals would. I'm imagining those cute little kiwi birds are now weighing in at about 8-10 kg and like to hunt in packs. Edit: Even with little evolutionary pressure, 65 million years is a long time, so some changes could occur even before humans get into the selective breeding game. At first, a the handful of these that survive the great extinction would likely be hungry. Some would try flying to their uttermost limits to find new lands, but even if any made it, the lack of Q. northropi outside of NZ means none survived to the modern era. The good part of this was less competition for the limited prey inside NZ while ecosystems recovered from the disaster. Super long distance flight isn't the advantage it once was. But, being on top of the foodchain has drawbacks. Population of prey grows supporting more top predators. The number of predators grows fast enough to eat prey faster than it can replace itself. Starvation then cuts the predator population. There is another source of food nearby. The oceans are also recovering. Grabbing a big fish like an eagle works, but more strength is needed to get back in the air after the occasional accidental water landing. More strength is needed to lift bigger fish. Range is sacrificed for stronger bones and muscles. More pressure in this direction comes if our Q. northropi decide to go for larger creatures deeper in the water. Instead of being limited to what's withing claw range of the surface, imagine something that big hunting like a diving bird. That tiger shark cruising along 12 meters down won't have a lot of warning when our now triphibious dino diver decides the shark looks tasty. Of course, plowing into the water at high speed and then moving underwater again requires stronger bones and muscles. More food is available, but weight goes up and range is further decreased. Strength goes up so that one adult human becomes an easy load and two becomes possible for larger specimens to handle. [Answer] **Domesticating the pterosaur implies domesticating the moa.** <https://en.wikipedia.org/wiki/Moa> [![moa and eagle](https://i.stack.imgur.com/oyFWF.jpg)](https://i.stack.imgur.com/oyFWF.jpg) > > Before the arrival of human settlers, the moa's only predator was the > massive Haast's eagle... > > > Polynesians arrived sometime before 1300, and all moa genera were soon > driven to extinction by hunting and, to a lesser extent, by habitat > reduction due to forest clearance. By 1445, all moa had become > extinct, along with Haast's eagle, which had relied on them for food > > > In your world the pterosaur plays the role of Haast's eagle. Flying predators would have been eating moas and so to keep the flying predators the Maori would have had to refrain from eating all the moas. A giant domestic meat bird could have more consequences on world history than kids flying around on dragons. Kids could be good messengers and maybe rapid couriers. A meat animal and conservation of lands for it to feed in implies a whole different and farsighted relationship between the early Maori and their new lands. Ultimately though I am not sure that domestic New Zealand species and land conservatorship would have made things go differently for the Maori post European contact. They would still be outgunned and disease would still ravage them. The ability to fly around on dragons would be noticed and greatly admired but it would be difficult to bring these big lizards back to Europe to show off. A question in my mind is whether the domestic pterodactyl and moa would survive contact. Polynesian dogs did not and dogs are pretty resilient. ]
[Question] [ Say that hypothetically, I wish to grow plants under the ocean. I construct a large glass dome and house the plants in a greenhouse contained in that done. How deep underwater could I plausibly have this dome before, before sunlight wouldn't reach it anymore? Could a series of farms based on this design be efficient and/or profitable? [Answer] # Not so good. [Seawater attenuates light rather rapidly](https://www.britannica.com/science/seawater/Optical-properties), reducing the merit a great deal. In the clearest ocean waters only about 1 percent of the surface radiation remains at a depth of 150 metres. And most of *that* is blue-green light, exactly the wavelength of light that plants do not use. As a hemispherical dome will be at least as deep as its height, the use of "large domes" strongly implies that the dome is situated in significantly deep water (more than 50m or so), and thus would lose access to virtually all beneficial light from the sun. You might have some success with very shallow (< 10 m) deep smaller greenhouses, but then they are both visible and subject to the vagaries of weather and tides, voiding any benefit of putting them underwater. Might as well make floating surface installations then. Obviously, if you provide artificial light the scenario is completely different, and depth is only relevant due to pressure. But then, with domes and artificial light, you might as well be on the ground, under the ground, in the ocean, or even in space. [Answer] It might be possible, the intensity of the light decreases the deeper you go in the water, more so for red light than blue light, see image below, which is from [this](https://www.researchgate.net/publication/304360662_Single_underwater_image_restoration_by_blue-green_channels_dehazing_and_red_channel_correction).[![enter image description here](https://i.stack.imgur.com/HyfHO.jpg)](https://i.stack.imgur.com/HyfHO.jpg) so After a few meters most of the red-yellow light is gone, so the plants would have to use green-blue light, now as PcMan points out most plants don't adsorb green light well/at all. But one of the forms of chlorophyll ([chlorophyll b](https://en.wikipedia.org/wiki/Chlorophyll_b)) does adsorb blue light. [![enter image description here](https://i.stack.imgur.com/L9U2w.png)](https://i.stack.imgur.com/L9U2w.png) There are also compounds that help broaden the colours of light a plant can adsorb, called [Phycobiliprotein](https://en.wikipedia.org/wiki/Phycobiliprotein). Plants can grow using just [blue light](https://gpnmag.com/article/effects-of-blue-light-on-plants/), but they tend to grow shorter. [![enter image description here](https://i.stack.imgur.com/CnMgL.jpg)](https://i.stack.imgur.com/CnMgL.jpg) Additionally some deep sea plants can grow at depths greater than 30m, some sea grasses have been found at [~$70m$ deep](https://sciencing.com/deep-ocean-plants-13427770.html). So assuming that there is enough light at ~$20m$ deep for food crops to realistically grow, then assuming that you have a field ~$50m^2$ and need ~$2m$ of height then you'd need a dome of radius ~$35-36m$. which would mean that the base of the dome is at a depth of $55m$ ($20+35$). As to if it is economical/profitable, I'd doubt it as the cost of constructing a dome of those proportions at that depth would be astronomical compared to the profit you would get from the crops. hopefully that helps [Answer] ## This is a really bad plan Not because it's inherently impossible, there are simply better alternatives. That will potentially be orders of magnitude more efficient. If you still want to go for this, you are likely limited to a few or tens of meters of water at best. The photic zone (where oceans are most productive due to the energy from the sun) ends at a depth of 200 m. No light gets beyond. Note that red and infrared light gets absorbed really fast, while green and blue do get deeper. As for better alternatives, you might want to try these. ## Aquaculture This is a rising industry and will become very relevant in the 21st century. Fish in cages, shellfish (which is extremely efficient in respect to food) and alge (which has the potential to become a basic industrial feedstock, as a lot of stuff can be made from the already extremely diverse set of species and genetic engineering (given the Luddites don't ban it) will only increase the number of options). Espacialy the deep ocean, where the photic zone never reaches the seafloor, could be turned from a region as productive as deserts into aquaculture production centers. ## Off-Shore Hydroponics Hydroponics are much more productive than traditional farms or greenhouses. Leavy greens and a number of vegetables can be grown at a profit in such a facility where all the environmental factors are optimised. Staple crops are a bit more difficult. The reason why one would do this out at sea is presumably that one seeks to cover the facilities energy and freshwater needs in an eco friendly manner by using [Ocean Thermal Energy Conversion](https://en.m.wikipedia.org/wiki/Ocean_thermal_energy_conversion). While power can be produced in an eco-friendly manner on land (nuclear, wind, solar), freshwater can be tricky. Desalination plants tend to mess with the local ecology by releasing high salinity brime back into the ocean. So, ultimately under water greenhouses may look nice in Minecraft, but are utterly impractical in reality. [Answer] The economics still won't pencil out, but if you really want to have an underwater area illuminated by sunlight, you'll need something like a solatube -- which is normally a tube that protrudes like a skylight from your ceiling through your roof. In this case, you'd need a sealed column that extends above the ocean surface that collects and reflects the light downward. Think of it like a giant periscope. (You'll also need some method for the column and the dome to resist the increasing water pressure, which is why it needs to be sealed at the top or your straw-like structure will implode.) This column could also contain your access shaft and maybe support something like a wind-energy system to provide some power to your facility. ]
[Question] [ I know it sounds kinda stupid, but I’m trying to create a really ominous figure that would always watch the player in this a hypothetical video game that I’m writing with my dad. We both agreed that having a huge 3 headed mechanical bird with a dead city on its back would be pretty creepy. The hypothetical bird would have a wingspan of about 160 miles (which is the size of Vermont from north to south.), it's sorta like [Vah Medoh](https://www.ign.com/wikis/the-legend-of-zelda-breath-of-the-wild/Divine_Beast_Vah_Medoh) from The Legend of Zelda: Breath of the Wild, but instead of using propellers, it would flap its huge wings. My question is, would this thing even be able to fly? And if not, does the “rule of cool” kinda help suspend the player’s disbelief? [Answer] NO. Not by flapping wings, that's for sure. **Problem the first:** Flyable air only goes up from the surface a short distance. Let's be *extremely* generous, and call this 10 miles. Your bird has a wingspan of 160 miles. If it flaps its wings more than 1/16th of their span, it slams them into the ground! 1/16th, that is barely a wiggle, not a flap. **Problem the second:** Wing lift is roughty proportional to the surface area of the wing, which scales as length \* length. Weight, which needs to be countered by this lift to be able to fly, scales as length \* length \* length. It is the old square-cube scaling law that always comes in to bite larger creatures. If your creature could fly close to the ground for ground-effect lift, and use not flapping but some system that moves air from above its wings to below them, you have a chance. In effect, you are then making a huge (really huge) hovercraft. Unfortunately, the end effect will not be very bird-like! Rather it would appear as the dust-storm to end all existence, and will leave a trail of devastation behind it. [Answer] The lifting power of an airplane grows with the surface of its wings, so roughly with the square of its dimension. The mass to be lifted instead grows with the volume of its body, thus with the cube of its dimension. At a certain point, all the rest being the same, the mass will grow more than the surface providing lift. The above, known as the square-cube law, already hints that it's unlikely such a thing can fly. Then you are topping it with * having to carry a city on its back (it disrupts air flow, thus wing lift, and adds weight) * having to constantly follow the player, who I suppose is walking (thus low fly speed, meaning low lift). This thing sounds very implausible, unless you sprinkle generous amounts of magic all around. [Answer] > > would this thing even be able to fly? > > > Yes, why not? It depends on what you mean by "flapping its wings". The useable atmosphere is not very thick, and it's actually way thinner than the wingspan. Also, the wing beat has a relationship with lift and obviously with the maximum air flow - which is air speed - which needs to be infrasonic. And the sonic barrier is just around 340 m/s; irrelevant for even the largest birds, but **very** relevant for your behemoth. To fly, the construct would have to flap the forward edge of its wings, creating an overpressure that would then be maintained by the rest of the wing, which would be stationary. It would then "float" over this air cushion. So, it's not a bird -- it's a *hovercraft*. And being beneath it wouldn't be an experience to recommend. Another possibility would be if the wings are selectively permeable - and at that point they're not "wings" but more like drone-wings, just with flutterers instead of rotary propellers. They gulp air from above and eject it from below. Wing movement becomes largely irrelevant (it could be synced with the fluttering, so more of a ripple than a wingbeat). [Answer] ### Maybe, if the lift isn't from flapping its wings. While the square-cube law would likely prevent a naive scaling-up of bird wings, it might be possible for such a thing to fly if it has some other form of propulsion. While you have indicated that you don't want propellers (and presumably you wouldn't want similar methods of propulsion, such as jet engines), there is one possible method of propulsion that would take advantage of having a large wing area: [electromagnetic thrusters](https://en.wikipedia.org/wiki/Ion-propelled_aircraft). Put simply, if the wings are electrically charged, it would be possible for them to ionize the air around them, and then thrust it downwards using magnetic fields to generate lift. Of course, lifting such a large structure into the air would consume a massive amount of electricity, so such a construct would require a very beefy power plant on board. Exactly how much energy it would require is beyond my ability to readily calculate, but perhaps a nuclear power plant would suffice. [Answer] Since it's a mechanical bird, it doesn't have to be built or fly like a biological one. Instead, build it like a huge parade float in the *form* of a bird. The square-cube law works in your favour here, at that size, you don't even need helium, just warm air like in Buckminster Fuller's [Cloud Nine](https://en.m.wikipedia.org/wiki/Cloud_Nine_(tensegrity_sphere)). Give it a back plate stable enough for a city, and slap on some propulsion (wing flapping won't really work at that scale for reasons explained in other answers, but part of the wings could maybe undulate); it won't be a surprise that the city is dead, though, since it will be far to high up to have a breathable atmosphere. Also, it wouldn't so much "follow the player" as "completely darken the sky from horizon to horizon". ]
[Question] [ Long story short: a cultural tradition of this (late medieval/early renaissance-ish) civilization is to put their deceased in a casket/boat/raft, and float them out into the ocean. Their belief is that they're sending their loved ones off to the afterlife, and at some point they float into the supernatural dimension where they wake up and join the afterlife. My idea is something along the lines of they get pulled into a current that eventually drops them off in a small cove or something far away. However, there's some things that still need develop. The cove needs to be well hidden, both from sailors along the coast and anyone who lives on the land. It should also securely collect nearly all the things that float downstream, because it wouldn't do to have random bodies floating around the ocean. So the question is, what is this "cove" like? How does the current work and how strong does it need to be? What material should the bodies be placed in? How plausible is this concept? This idea is pretty flexible. There's not much geography planned for this region yet, and I can probably work with whatever you guys can suggest. Also if the cove idea doesn't seem plausible, I'm open to any other explanations (maybe they get sucked underwater and lie on the ocean floor?). Pretty much any input helps. [Answer] **The gyre.** [![gyre](https://i.stack.imgur.com/NWqjV.jpg)](https://i.stack.imgur.com/NWqjV.jpg) [source](https://phys.org/news/2018-09-phytoplankton-survive-ocean-gyres-nutrient.html) <https://phys.org/news/2018-01-temporary-bathtub-ocean-flotsam.html> Your dead folks stay at sea. They go around and around in their little boats. Boats from various villages all gather in the gyre. Some have been there a long time. No-one comes to the gyre because it is far out to sea. No-one comes but the dead. > > The experiment conducted in the Gulf of Mexico near the site of the > Deepwater Horizon oil spill placed hundreds of drifting sensors to > observe how material moves on the ocean's surface. Rather than spread > out, as current calculations would predict, many of them clumped > together in a tight cluster. > > > "To observe floating objects spread out over a region the size of a > city concentrate into a region smaller than a football stadium was > just amazing," said first author Eric D'Asaro, a UW professor of > oceanography. "We knew there would be some concentration, but the > magnitude seen was quite stunning." > > > The original article with explanation is here: <https://www.pnas.org/content/115/6/1162> There is one live person in the gyre with the dead. She was not as dead as people thought when they put her to sea. She is an able fisherman and has lived on fish and rain, as well as gifts put to sea with the dead folks. She is happy to see your people. She was happy with the people that were already there. [Answer] Simply put, without a living person actively controlling it, the boat will sooner or later either fill up with rain water or topple over due to waves. When that happens the body is obviously taken care from scavenging sea creatures and the boat sinks. Note that in context like oceanic atolls the sea is pretty calm within the limits of the atoll lagoon, but then gets pretty rough immediately out of it: [![enter image description here](https://i.stack.imgur.com/WseyV.jpg)](https://i.stack.imgur.com/WseyV.jpg) this makes venturing outside the lagoon a challenge, even more if there is nobody to control the boat. [Answer] **One species' dead bodies is .. another species' food**. Seas and isles have ample number of creatures that are still being discovered today, so you can even invent a species if needed. With a late medieval/early renaissance-ish civilization, there is a good chance of highly reliable boat technology being missing, as well as the boats of the dead being cheap knockoffs that can only go short distances beyond regular vision to save on resources and get more money. > > What ocean geography causes bodies to “disappear”? > > > Because in the ocean, the body is a rich source of food, So, you only need to provide enough time for the natural processes to happen before anyone notices them. Fortunately, the volume of sea based traffic was much lower during the late medieval era, and the number of uninhabited areas was large, so you can have your boats travel to 1) An archipelago 2) rocky beaches, or 3) An area with larger [Rogue waves](https://en.wikipedia.org/wiki/Rogue_wave). > > How does the current work and how strong does it need to be? > > > A plot armor of none of the inhabitants/sailors going in the direction of the dead to respect the dead and water house of dead can be very helpful here. Initially, your current needs to be a moderate surface current. The design of boat should help be like a [coracle](https://en.wikipedia.org/wiki/Coracle), the boat should be able to float easily for some time before it goes beyond the visual range. Later, another current needs to be merging with the original so as to make it stronger. Could be like a madagascar current meeting a circumpolar antarctic current, but more localised. > > maybe they get sucked underwater and lie on the ocean floor? > > > So, the current takes the boat to one such area, where it (boat) finally breaks down. The area should be full of species that eat the dead bodies. Could be an island of mythical [Berbalangs](https://en.wikipedia.org/wiki/Berbalang) who know how to swim short distances, or a colony of [sea cucumbers](https://en.wikipedia.org/wiki/Sea_cucumber) that eat the dead bodies once the boat capsizes. Regular seafarers avoid the area/current because of treacherous geography. [Answer] Ocean currents are caused by a variety of things like planetary rotation and salinity gradients. It could be that the culture is located alongside one of the dominant paths which will carry away any free floating debris. This can be subtle enough to enable regular sailing and even swimming, with return one way being easier than the other ("Call of the Dead" as the locals might call it). You can then schedule funerals for outgoing tide to give them a push into the current. Anything that floats either on the surface or below it is suitable. The destination can be very far away, in a sacred region where nobody is allowed to go or through some treacherous water that will sink boats (and the dead don't care about being drowned for a while). The cove can be at a bend in the current so that the floaters are thrown from it into a concavity in the shoreline that has been eroded away by the water. There are existing well established paths that might vary with weather and season but display consistent directionality over longer periods. There is a fun story of plastic pollution mapping these: <https://en.wikipedia.org/wiki/Friendly_Floatees> And even something called the global conveyor belt: <https://en.wikipedia.org/wiki/Thermohaline_circulation> [Answer] A couple of things immediately spring to mind. First is that the dead float into a region of non-buoyant water. This could be caused by (for example) a thermal vent on the ocean floor that releases significant amounts of gas bubbles into the water. This lowers the density of the water. When your boats enter that region, they find themselves significantly denser than the water and rapidly sink. A structure like this would be a hazard for regular ship navigation as well. Perhaps your culture sees this oddity in the ocean as the gateway to the underworld, and all but the dead steer clear of it. Another option is that your terrain has some seaside cliffs. In several places, those cliffs have eroded away to form deep [cave systems](https://en.wikipedia.org/wiki/Sea_cave). These caves formed a long time ago, when the sea was much shallower. Now, their openings are completely underwater at high tide but during low tide, the lip of the cave opening just barely peeks above the water line. These caves would be impossible to see while standing on the cliffs, and difficult to see while on a boat without getting dangerously close to the rocky cliffs. When your dead are set adrift, they never actually make it very far from land. After the tide drops to its lowest point and starts to come back in, the drifting dead get swept back in with the tide and get sucked into the caves just before the tide rises high enough to prevent them from drifting back out. The insides of the caves are full of debris and jagged rocks, and any rafts entering the caves quickly get smashed to bits. The remnants of the rafts will eventually get swept back out of the caves but by that time, what's left in indistinguishable from ordinary driftwood or natural marine debris. [Answer] As pointed out by many other people, dead bodies are an ample source of food. However, while boats would capsize or sink given enough time, the tide may very well bring some boats back to the shore. The implications of this is that their loved one was rejected by the god of the afterlife or perhaps even "awakened" and used their new spirit powers to come back. I'm no expert on tides or currents, but given that Padre Island is in the Gulf of Mexico and that currents bring things from all over said Gulf to the shore, it seems more than likely a gyre won't solve that problem. However, there is a solution you may want to consider: *merpeople.* If there are furtive (but likely curious) merpeople living in the coastal areas, they will soon find the boats and realize there are bodies inside. Out of curiosity, hunger, pragmatism, or perhaps all three, they will take apart the boat (wood can be used for construction or made into weapons) and eat the bodies. In fact, out of some desire for fairness, dying merpeople may crawl (or be deposited by friends or family) onshore and be found by the humans, who then may or may not eat them. In fact, the merpeople may even write *Eat Me* on them before crawling onshore (if they've learned or somehow already know the human language). This will effectively hide (and deal with) the bodies, not to mention keep the boats from returning. In conclusion, I hope this helps! [Answer] **They get eaten** @AnshulGoyal mentioned predators but I'd like to add to that with a specific real world example that involves IRL funerary barge practices. The Ganges river is home to a very large, predatory catfish known as the goonch (*Bagarius yarrelli*). In India there is a tradition of putting loved ones on floating funeral pyres and sending them adrift down the Ganges. However, this causes the local goonch to start getting a taste for human flesh, and the sudden influx of nutrients into their normally nutrient-poor environment also caused them to start growing to extremely large sizes of more than two meters. The funeral barges normally break apart when burned but the goonch are big enough that a sufficiently motivated one could drag them under. Given these animals have huge mouths to suck down their prey and can swallow a small child whole, after a certain point there is going to be nothing left of a human body disposed down the river. The goonch eventually started attacking *humans*, and notably when this happened the people they attacked just vanished. No body was ever found. Now, it's not a foolproof strategy for making sure people's bodies are never found. There are issues today in the Ganges where people are finding bodies that were apparently disposed of by people trying to illegally give their loved ones a river funeral. Part of this is because populations of goonch and other river predators like mugger crocodiles are getting low due to pollution in the Ganges. But out in the ocean where there are a lot more predators, especially in a setting that perhaps doesn't have as much human exploitation of the marine environment, and it would be really hard to find anything left. A good example of this are modern oceanic whitetip sharks (*Carcharhinus longimanus*). These animals are *always hungry* because they spend their existence on the brink of starvation, are really curious towards new stimuli, and are known to be the number one bane of shipwreck survivors because they have no fear of humans and will eat people stranded in the ocean. Some studies have even suggested they may have even learned to follow signs of oceanic distress like boiler explosions because they've learned there's a chance for a meal. If a species like that has learned that your people are sending meat out to sea, those funeral barges are going to get torn apart and leave almost no trace the moment they sink (if the predators don't sink them beforehand). ]
[Question] [ In [another question](https://worldbuilding.stackexchange.com/q/194648/47324), I asked how airships could be made more viable. The first (and so far only) promising solution I came up with is to increase the density of air. In the real world, air (on Earth) is composed mainly of nitrogen (~80%) and oxygen (~20%). I'd like to reduce the nitrogen content in favor of a heavier gas. Unfortunately, most heavy gases seem to be toxic in one way or another, although both Krypton or Xenon seem to be ok(-ish); Radon would be the next step in the noble gas category, but it's radioactive. Changing the air composition from a (simplified) 80% nitrogen, 20% oxygen to 50% nitrogen, 30% xenon, 20% oxygen would raise the density from about 1.25kg/m³ to about 2.68kg/m³, roughly doubling the buoyancy. Hence my question: what would the effects of reducing the Nitrogen percentage in air in favor of a heavier gas such as Krypton or Xenon be? Addendum: I since read [this question](https://worldbuilding.stackexchange.com/q/19508/47324), which has an answer that states "xenon makes an excellent general anesthetic, so let's not adopt an atmosphere which renders us unconscious". I'm open to simply ruling that this property does not exist in my world (perhaps humans and other creatures developed an immunity) if Xenon turns out to be the otherwise best option. [Answer] A very likely risk is that the heavy gases would stratify at the lowest heights, displacing lighter gases and making it an anoxic environment. A situation where normal atmospheric mixing is stopped is called [inversion](https://en.wikipedia.org/wiki/Inversion_(meteorology)) > > Given the right conditions, the normal vertical temperature gradient is inverted such that the air is colder near the surface of the Earth. This can occur when, for example, a warmer, less-dense air mass moves over a cooler, denser air mass. This type of inversion occurs in the vicinity of warm fronts > > > Temperature inversions stop atmospheric convection (which is normally present) from happening > > > The formation of anoxic regions due to heavy gases happens already during [limnic eruption](https://en.wikipedia.org/wiki/Limnic_eruption): > > A limnic eruption, also known as a lake overturn, is a rare type of natural disaster in which dissolved carbon dioxide (CO2) suddenly erupts from deep lake waters, forming a gas cloud capable of suffocating wildlife, livestock, and humans. > > > Once an eruption occurs, a large CO2 cloud forms above the lake and expands to the surrounding region. Because CO2 is denser than air, it has a tendency to sink to the ground, simultaneously displacing breathable air, resulting in asphyxia. CO2 can make human bodily fluids highly acidic and potentially cause CO2 poisoning. As victims gasp for air, they actually accelerate asphyxia by inhaling CO2 gas. > > > This would be a high risk in areas with low atmospheric mixing. Of course above those areas, due to the stratification, buoyancy would also be reduced. [Answer] You would sound like Darth Vader <https://www.youtube.com/watch?v=irz-diec-qg%3Frel%3D0> Although the effect is only really significant at very high densities. There is a bit of a problem with the choice of gas, many gases at high concentrations have active biological properties. For example noble gases from Argon upwards possess anesthetic properties, though only significantly so for Xenon or higher. How about just, you know, **increasing the ambient air pressure**, thus increasing air density? If you make the atmosphere 95% nitrogen and 4% oxygen, at 5 bar (5 times Earth Sealevel pressure), then your atmosphere is still perfectly breathable by normal humans, and your airships get 5 times the buoyant force from their balloons. Whether lighter-than-air gas, or simple heated air, makes no difference. 5 times the air pressure means 5 times the air density means 5 times the lift force per volume of balloon. For normal humans, 5bar is pretty much the limit. Nitrogen narcosis kicks in a bit below this, actually, but some measure of acclimatization is possible. The reduced oxygen content will ensure appropriate partial pressure of Oxygen for breathing. [Answer] It depends on the circumstances of your world. If a high Xeon atmosphere world did exist (very unlikely) then any creatures that evolved in the atmosphere would not suffer anesthetic effects. If high concentrations of Xeon were somehow introduced (!) then any life might suffer anesthetic effects. Xeon would probably be found at slightly higher concentrations in the lower Troposphere than say in the Stratosphere but general atmospheric wind, rain and convection effects would almost certainly ensure a good deal of mixing. Note that carbon dioxide concentrations do not vary in the atmosphere (<https://www.jstor.org/stable/1934239?seq=1>) despite carbon dioxide being a heavier gas than oxygen or nitrogen or argon. One way to increase buoyancy would be to make the world cold. Cold gases are denser than hot gases. If the interior volume of the lifting gas were to be heated (by chemical, magical or solar means) its lifting capacity would be increased. [Answer] I agree with the answers that suggest givining your planet a denser atmopshere. I will link to calculations suggesting that a breathable atmosphere could have up to about five times the sea level pressure of Earth's atmosphere - possibly much more. You might also want to consider giving you planet a higher or lower surface gravity, whichever will tend increase the buoyancy of gases which are lighter than the atmosphere. Of course every element or compound which might possibly be present in an atmosphere will become toxic if it is present in too great a concentration. Even Oxygen, vitally necessary for life, becomes toxic in excess amounts. So if you increase the concentration of every probable and improbable element and compound to the maximum that humans can tolerate, you will find an absolute upper limit to the density of atmosphere at the elevations where humans (and beings with the same requirements) live. *Habitable Planets for Man* Stephen H. Dole, 1964, 2007, discusses the environmental requirements of humans. And the 1964 edition is online: [https://www.rand.org/content/dam/rand/pubs/commercial\_books/2007/RAND\_CB179-1.pdf[1]](https://www.rand.org/content/dam/rand/pubs/commercial_books/2007/RAND_CB179-1.pdf%5B1%5D) On pages 13 to 19 Dole discusses the atmospheric requirements of Humans. On page 15 Dole states that the normal atmospheric pressure of oxygen at sea level on Earth is about 149 millimeters of Mercury. The overall sea level atmospheric pressure is 29.92 inches of Mercury, or 759.968 millimeters of Mercury. On page 19 Dole says: > > To summarize, then, the atmosphere of a habitable planet must contain oxygen with an inspired partial pressure of between 60 and 400 millimeters of mercury and carbon dioxide with a partial pressure roughly between 0.05 and 7 millimeters of mercury. In addiiton, the partial pressures of the inert gases must be below certain specified limits and other toxic gases must not be present in more than trace amounts. Some nitrogen must be present so that nitrogen in combined form can find its way into plants. > > > So carbon dioxide would be a very bad choice to increase atmospheric pressure. According to table 2 on page 16, the approximate upper pressure limits for nitrogen and argon would be about 2,330 and 1,220 milimeters of mercury. So a breathable atmosphere could possibly have a total of pressure of 3,950 milimeters of mercury of nitrogen, argon, and oxygen, which would be about 5.197 times the sea level pressure of Earth's atmosphere. I note that Dole believes that helium and neon could be present at even greater pressures in a breathable atmosphere, but the upper limits are rather uncertain. And of course newer research may have changed the safe limits of various atmospheric gases. ]
[Question] [ Numerous science fiction works feature super soldiers wearing power armor (powered exoskeletons fitted with armor plates that provide varying degrees of protection, strength, speed, endurance, and other capabilities), such as Halo, Warhammer 40k, Fallout, etc. Sometimes, these suits of power armor are painted in camouflage patterns. However, I have read that breaking up your silhouette is very important, and that even if you wear colors similar to those of your surroundings, you can still get spotted easily if you stand out as a person-shaped object. I would imagine that the hard lines present on a suit of power armor would be even more noticeable than a regular soldier. Because of this, wouldn't it be wise for soldiers wearing power armor to wear a baggy cloth layer or some sort of ghillie suit outside? The IDF already does something similar, with their Mitznefet helmet coverings. [Answer] **1. Camo** One thing about combat in nature — nature has very few sharp lines and edges. A powered suit would be easy for software to detect simply because the motion of the suit would produce a hard edge against its background no matter how it was painted. However, consider this fellow (courtesy [Orange Tip Tactical](https://www.orangetiptactical.com)): [![enter image description here](https://i.stack.imgur.com/U3SeUm.jpg)](https://i.stack.imgur.com/U3SeU.jpg) You see, even powered armor isn't invulnerable. It's always a good idea to make it harder for the enemy to see you. **2. Ceremony** It's certainly true that tanks and artillery look great rolling down the street during a parade, but nothing inflates El Presidente's ego like seeing his latest Presidential Seal adorning all his soldiers! (Image courtesy [Pinterest](https://www.pinterest.com/zacgilley/tabards/)): [![enter image description here](https://i.stack.imgur.com/AUD56.png)](https://i.stack.imgur.com/AUD56.png) *If you're tempted to say, "yeah, but the armor could just be painted that way!" Let me suggest that you never underestimate the pomp and grandeur of pennants and flags....* **3. Thermal/Weather/Weapon Protection** Most fictional portrayals of powered armor show them to be impervious to everything around them: water, heat, acid... But in reality it's a good idea to protect the articulation (joints). Water is insidious, and if it's bad, acid is even worse. A powered armor that's 100% proof against every acid or base is hard to imagine, and joints will always be susceptible. Also, you really can't pack every form of protection into powered armor. I personally love the depictions of marine grunts in StarCraft, but if the suits really were that way, you'd have to dislocate (even separate) arms and legs from the body just to get them into the suit. What this means is that you can't perfectly thermally insulate the suit, which means a good flame thrower can be a problem. Cloth coverings allow the suit to be protected from such environmental and combat problems. In fact, you can think of the cloth coverings as a form of ablative-ish armor that can be "burned away" as it encounters things that can hurt (if slowly) the much more expensive powered armor. This is likely a reason why ablative armor exists for real-life tanks (Image courtesy [Omsk State University](http://www.univer.omsk.su/students/lachin/%7Etanks.htm)). [![enter image description here](https://i.stack.imgur.com/Bpj0am.png)](https://i.stack.imgur.com/Bpj0a.png) **4. The lack of pockets can be a problem** Finally, the last thing you want to waste expensive powered armor on is a few extra mags and a camp shovel! There will always be a reason to haul supplies around. Yes, this could only be a backpack, but why waste all that power? (You know, *Powered* armor!) Cloth would allow all kinds of things to be strapped, attached, and carried. Add an Acme Quick Disconnect system to drop it quickly in case of combat (Image courtesy [Ruck for Miles](https://www.ruckformiles.com/guides/army-ruck-march-standards/)). [![enter image description here](https://i.stack.imgur.com/ipV3ym.jpg)](https://i.stack.imgur.com/ipV3y.jpg) [Answer] It could be a good way to keep the sun off your armour, and keep you from building up excess heat. Cloth was often worn over armour for this very reason. For stealth, a ghillie suit is king, you'd definitely want one. Someone mentioned that it could get caught up in joints... but if power armour is that delicate that a shirt getting caught in it messed it up, then it's not combat-practical. Note that for some purposes, camouflage makes little difference, or you might even want to be seen. SWAT wears all black so as to look scary and shock the enemy, for example. For breaking up your silhouette, even if it's baggy, I doubt running in power armour will be particularly stealthy. Too baggy might make it more obvious. You might want to go for something like elbow-length, flowing sleeves, to break up the arms and shoulders, and maybe a long cowl the break up the head and neck, and a skirt to hide the legs. That would be manageable, and it can work with a ghillie suit. Hope this helped. [Answer] Cloth coverings would easily snag on things or be damaged by battlefield conditions. It would be better to use [disruptive coloration](https://en.wikipedia.org/wiki/Disruptive_coloration) and paint the armor in such a manner that its outline is no longer distinctive. [Answer] Cloth coverings would be a very sensible idea for power armors. I could prevent water, dust and mud from getting into sensitive mechanical places. Depending on the weather proofness of power armor, i would find it plausible if power armor is required to have weather proofing done every time it is put on. In fact [humanity does cloth coverings for tanks](https://www.quora.com/Why-did-some-tanks-have-a-tarp-looking-material-on-the-front-of-the-turret) for this purpose. I doubt cloth coverings would bring much stealth benefits unless: * the power armor is curled up into something rock like looking and the cloth covering helps * there is noise absorbing material under the cover which might hide some sounds. However a complete cover might result in problems with getting rid of heat, so there are many thing that need to be considered when deciding to use them. ]
[Question] [ Individuals are born with mana, which accounts for their life force and has a hand in determining the strength of their spells. Mana level and composition is determined by a person's genes, which they inherit from a mix of their parents. There are three factors that decide magical power: 1. Maximum reserve: This describes the level of reserves that a person contains. Individuals with extremely high mana reserves represent the strongest of witches, and can access the most powerful spells in mage craft. However, they have more difficulty in controlling and directing the flow of their mana. As a result, their spells take longer to perform. They also have a slow recharge rate, lengthening the time period between spells. 2. Focus rate: This describes the level of control a person has over their mana flow. Individuals high in this category have small reserves of mana, and can be considered weaker than average. However, they have much more control, allowing them to be more precise and direct. While those with high reserves are battering rams, they are a scalpel. They also have slow recharge rates, leading to longer intervals between spells. 3. Recharge rate: This is the category that most people fall into. They have average reserves of mana, as well as typical levels of control over it. They have a higher rate of recovery, allowing them to recharge their mana quicker than the other categories. Very rarely, a person is born with high stats in all three sections. These individuals have large power levels with excellent control over their mana, as well as quick recharge rates. These individuals are considered the diamond in the rough, and are the most powerful and formidable mages in the world. The way evolution works, successful mutations are supposed to be inherited by descendants, as they allowed the parent organism to better survive and thrive compared to others of their race. As offspring becoming more successful, they eventually supplant others of their kind and become dominant. In the case of these badass mages however, their superiority only lasts once a generation. Their traits that make them powerful are not passed down to their offspring. Families who have instances of these mages often try pairing them in order to create a line of powerful offspring, but these are never successful in creating the desired outcome. Why would this be the case? [Answer] **These traits do pass on, but they aren't genotypes, they're phenotypes.** In our world we have a rather peculiar event regarding the fur color in some fox species: while in the summer their fur is usually "normal", once the winter arrives their fur color starts changing to white. This is due to the temperature influencing the genes which control pigmentation, with the sex of some reptiles being conditioned to this exact same environmental condition. So here we can already see the issue: a phenotype (physical traits of an organism) isn't conditioned only to their genes, but to outside pressures that influence how these genes will manifest. [Water fleas](https://www.popsci.com/science/article/2011-02/water-flea-genome-most-complex-yet-and-may-help-scientists-study-organisms-response-stress/) might be the best example of this: they have one of the most complex and long genomes in any animal. The reason? These genes help them adapt to various scenarios, growing structures such as helmets, spikes and other, as a way to better adapt to their environment and as a reaction to stress. Your case could be experiencing a very similar scenario, in which the way these super mages grew was what allowed these traits to be expressed. Maybe it happened due to them living a much harsher life that wasn't shared by their preciously guarded and protected offspring, or by sheer stress related to the need of have more mana faster and control it triggering these changes in order to increase their chances of survival. This could easily result in a natural selection situation as well, in which a stressful and dangerous childhood is what allows these traits to appear. The stressful and dangerous conditions, however, will naturally limit the number of super mages due to the high mortality rate characteristic of such a harsh environment necessary to awaken the supermage genes. That way, if you don't help them they might die, but if you help them, they won't develop. It'll be a matter of one's cunning nature, luck and adaptability to be able to survive and live on, growing to be a force to be reckoned with, both due to their high power and to their great adaptability, fast thinking and cunning nature, which allowed them to survive in the first place. Edit: to further decrease the number of successful Mages and the probability of achieving one, make the genes responsible for this condition recessive and more than one, preferably spread apart relatively from one another, this will ensure that simply having the necessary genes to be a supermage candidate will be extremely rare. The further apart these necessary genes are from one another, the harder it is to get all of their pairs, so it's a good way to further control the probability of a successful supermage being birthed and maturing under the necessary pressures, depending on how common or uncommon you want this condition to be. The genes responsible for the condition being recessive can also explain why normal parents could still give birth to a potential supermage child. [Answer] Similar to ProjectApex answer but different pressure: in parrotfish species, if there are no males In a school, one or two of the females will change gender. The presence of the male hormones from those couple males keeps the others as female. Your badass mages are normal genotypes that are born at extreme nadirs of magic. Evolutionary pressure is against having too many badass mages in an area: that leads to conflict, which doesn’t help the species. When magic dips low enough, one or two badasses will develop. They have kids and bring the next generation up to “normal”, so there’s no dip. You might have a rare case of badass spawning badass if the parent dies before the kid grows up and the kid grows up in an age of low magic. But that would require the parent have been a badass who didn’t use power much. [Answer] <https://en.wikipedia.org/wiki/Heterosis> It is not some particular gene, but a combination of genes in a heterozigous combination for all of them. Whoever you cross-breed the mage to, you get an average type of children with 99.9% probability. It is equally or even more probable to get the superior phenotype by just leaving people to procreate however they like. To complexify the situation, each of these alleles is prevalent in some caste (race, whatever) and rare, but not unseen outside its home group. Using some "educated eugenics" you can improve chances by encouragin contacts between people of mixed race (but you will get mages of doubly-or-more-mixed race). [Answer] Genetics do not confer an absolute advantage or disadvantage. A gene (or combination thereof) may be advantageous in one environment and not at all in another. Even if the genetics of an individual are advantageous (at least in theory) there are many ways in which that advantage is not passed on to descendants. The individual may not mate and/or the off-spring may die from disease or disaster or war. The key notion here is that evolution does not have a direction. More evolved does not translate into superiority, only to the notion that the entity is more suited to the current environment. Change that environment and the entities must evolve to fit that new environment or die. Even when the genetics and the environment line up, evolution merely says that the tendency is for the more suited entities to survive. Random events can easily disrupt this pattern. [Answer] Personality. There may be a minimum level of intelligence required to be an engineer, but intelligence only helps if you have a certain problem-solving mindset. If you don't have the passion for it, you have a lot of other options, but if you obsess over it constantly anyway, you can get good. I'm 6'4" tall, but was never good at football, because I have no interest in it. With a passion for football, I'd probably be quite good, but if I don't spend hours a day drilling the basics, that's not going to happen. Everyone thinks they want to be rich, but most rich people are that way because they obsess over money and finance. Presumably magic is a discipline, and a person's skill at any discipline is a combination of relevant genes and a personal obsession with the basics...possibly in multiple subdisciplines for a working above the card trick level. [Answer] The combination of genes that are required to produce very high magical ability is an extremely delicate balance. It's not just a gene that dictates the "ability score", but rather a complex intermingling of different genetic factors, and a change in even just one of these genes can undo the whole construction (for want of a better word). Furthermore, the genes that dictate the three different abilities are at odds or in competition with one another somehow, which makes it all the more difficult to be good at all three. So for someone who is good at all three abilities, if their offspring is missing just one of the many factors (which is likely because they will have inherited conflicting genes from the other parent) then the high powers will not be passed down. Furthermore, these genetic factors are completely different in a woman than in a man, so even if two of these all-powerful mages get together, they won't necessarily produce an offspring with the same ability. ]
[Question] [ In my medieval-fantasy world, there’s a secret civilization with modern technology. A “powerful” dragon accidentally came across them and they became good allies. The dragon was introduced to the concept of aircraft and it wasn’t long until she decided to ride one. The dragon shrunk into a more humanoid form, with the appropriate limbs and digits. The dragon loved to fly in a fighter plane, so much so that she refuses to fly under her own power as much as before. Why would this be so? [Answer] I can think of four\* reasons why the dragon would want to pilot a fighter plane rather than fly in its dragon form, with the three reasons leading to the most important fourth one. --- **Novelty** One reason would be similar to why people watch movies or play games; to do something novel that they normally cannot do. Rather than flying with their own body, they can control the plane to do maneuvers, like a sort of game. --- **Aerodynamics, Speed, Stamina** Apart from that, a dragon’s normal flying form is probably the last thing anyone would think of when considering aerodynamics. A dragon, assuming without the use of any magics, would probably fly no faster than a bird when in the air. To fly quickly at a reasonable speed would also quickly consume the dragon’s stamina or magic as well. Compare that to a fighter plane, which can easily hit subsonic or supersonic speeds, and consumes no stamina to run, only the measliest of fossil fuels. It would also be much more agile and potentially deadly, being able to fire missiles rather than using up the dragon’s magic powers. Not to mention, in the event of emergencies, the dragon still has its dragon form as backup, with a full tank of stamina and magic. --- **Organic vs Mass-Produced** Finally, considering the existence of fighter planes in such an age, a dragon in dragon form would be nothing more than a sitting duck. Due to its slow speed, it would practically be a stationary target for fighter planes. Even if it has magic, if it is swarmed by fifty or five hundred fighter planes it would probably eventually run out of magic and be forced into a sorry state. Even though the secret civilization is the only one possessing such a technology, who knows if that will be so in the future? By forming an alliance, the dragon gets to try out the new technology and find its weaknesses, giving itself an advantage should other civilization adopt similar technologies. This problem mainly exists because the dragon is a single, organic entity, meaning it has a limited amount of magic and stamina. The fighter plane *is the culmination of the efforts of countless human beings*, and can be *mass produced*. As a single organic entity, the dragon cannot withstand the might of an entire civilization, and thus, needs to make use of their efforts to improve its own efficiency. --- **King of the Skies** *Inspired by the discussion in the comments* The most important reason, since the dragon itself has probably considered the prior three. Assuming the dragon is extremely powerful, and capable of magic (due to shape-shifting), giving it a fighter plane would be the equivalent of making it the King of the Skies. In dragon form, there are weaknesses that allow enough enemies to swarm it and tire it out, but what if that same dragon was in a fighter plane? Assuming a dragon, to fly, would need to use magic to reduce drag, function as an air-brake, and alter its ability to withstand high-G turns and maneuvers, can't these things be applied to the fighter plane too? You would then have a fighter plane that is much quicker than its peers, capable of doing inhuman maneuvers mid-air, and piloted by a dragon with faster/better/stronger reflexes and an insane amount of aerial combat experience. Even if they sent hundreds of fighter planes to go after such an opponent, would anyone be capable of shooting down or even catching up to such a fighter plane? Using the human technology would allow the dragon to remain the king of the skies, no matter how much human technologies progress. --- **Summary** In conclusion, the fighter plane is probably novel to the dragon, and also allows it to fly faster, save energy, and be competitive in a tough job market. By making use of the highly advanced fighter plane, with its experience and magic, the dragon would remain the dominator of the skies. [Answer] Convenience and speed. Unless your dragon has some magical powers helping it along, there is no way she ever could achieve the same speeds as a fighter plane. Also, who doesn't prefer driving a car over walking? If it can be easier, then why not use the possibility? Now how she will afford the fuel is another question. We all know how stingy dragons can be about parting with their hoard. [Answer] I'd say that the best reason is that she can't fly properly anymore for some reason, and flying an airplane is the closest she can get. Maybe she has something like a torn wing that didn't heal properly, so she can't fly very well naturally anymore. If she were injured helping someone from the secret civilization, this could be why she was given an airplane in the first place. ]
[Question] [ Fantasy writers tend to prefer forms of combat that predate guns, because they are more showy, and they involve close and long-duration combat with an identified adversary instead of shooting at distant specks and twitch-spraying bullets in close quarters. Fantasy writers also like to use settings where guns are technologically possible. This leads to a lot of fiction where for some inexplicable reason guns were never invented, and warriors duke it out with swords in train stations while taking calls on their cellphones. If the universe has the same physics as ours but history can be changed at will, what's the latest technological era into which the total dominance of firearms over all other weapons can be delayed without abandoning rationality completely? What historical events or trends would have to be altered? [Answer] > > What historical events or trends would have to be altered? > > > It is hard to point at a single instant in time and say that yes, that was the turning point, but by way of an example I'd look to the [fall of Constantinople](https://en.wikipedia.org/wiki/Fall_of_Constantinople) in 1453. The Ottoman army used some exceptionally large cannon that took hundreds of men to manoeuver and operate, and (to grossly oversimplify) used them to wreck the defenses of a walled city, end the Roman empire and wrap up the european middle ages (depending on who you ask). It would have been quite unambiguous for all involved that when those cannon brought the walls down that the world was changing and that gunpowder was the future of warfare. They were behind the curve, though. The cannon that they used were *already* the products of a long tradition of gunpowder warfare. [Fire-arrows](https://en.wikipedia.org/wiki/Fire_arrow) had been about for hundreds of years, and had evolved into the precursors of rocket artillery. Gunpowder hand grenades, the precursors to more substantial bombs and explosive shells, were similarly old. Cannon had been developed some 200 years previously, and had been steadily improving and spreading during that time. Basically, you'd need some kind of apocalyptically devastating event to occur in China about a thousand years ago to slow all that down... plague, or meteorite strike *might* have done the job but really, the genie was already out of the bottle by then. By the time Constantinople fell it would have been far, far too late. To slightly misquote William Gibson, the future was *already there*. It just hadn't been widely distributed yet. > > instead of shooting at distant specks and twitch-spraying bullets in close quarters > > > Do note that it took hundreds of years of scientific and technological development to develop guns capable of that sort of thing. Troops armed with mêlée weapons were still found on battlefields for hundreds of years... spanish tercios were still useful units in the mid 17th century, some 200 years later, and cavalry armed with lances and sabres were still fielded in the *19th century* to occasional good effect. That's the best part of *400 years* of sword-wielding heroes (or villains) and knights in shining armour across Europe. If you can't make a good story out of *that*, it seems like maybe you're just not trying! > > Fantasy writers tend to prefer forms of combat that predate guns, because they are more showy, and they involve close and long-duration combat with an identified adversary > > > Its because they like lazy stereotypes. That's ok, because the readers like them too. The advent of gunpowder siege weaponry rather ruins castles and walled cities, and everyone likes a good fortification, but everything else associated with those well-worn fantasy tropes would have carried on working just fine for a long, long time before it became unambiguously foolish to go to war without firearms. [Answer] Before the early 1800s, pretty much every discovery in the field of Chemistry was a mistake or total trial and error. If the Chinese didn't screw up some life-lengthening elixir experiments around 850 AD, then they would have never invented gunpowder, and we may not have had guns for quite some time. It is important to note that Gunpowder was not one of those inventions that was accidentally discovered in more than one place. This suggests it really was much more of a fluke than an inevitability. However, between about 1600-1800, experimentation led to the discovery of nearly 50 elements at which point the scientific community started having enough data to predict the properties of yet undiscovered elements and chemical compounds giving birth to what we think of as modern chemistry. While it is unlikely that no explosive chemicals capable of firing a bullet would have been discovered by 1800, it would have been impossible for scientists to not be able to predict what they would need to make an aqidate low-yield explosive to get the job done once they reached this point. Since the world was already industrialized by 1800, it would not have taken very long at all to get from no guns to them being the dominant weapon. [Answer] I think the biggest thing that would have to be altered is the amount of war and the scale of the conflicts that occur. It's hard to say for curtain obviously but I don't think it's particularly unreasonable to assume guns didn't become a mainstream weapon in a world that's at even our current level of advancement. Guns didn't become widely used as a "main" weapon as they are today until around 1835 when the colt revolver came to be. It was the first gun that used the ideas of the industrial revolution mixed with weaponry. I personally think the biggest issue becomes the amount of conflict. If your world is for example run by one giant government or has some way that large scale conflict have been prevent it's possible no one would of invented it. The problem really becomes less about if guns are used but if they aren't how did other tech come around since a huge amount of tech we use was researched using war money. Hope that helps! [Answer] A bit drastic but one way to achieve this would be to limit the supply of metals. If the physical circumstances of Earths formation had been different and there were no (or very few) concentrated sources of metal ores near the surface in inhabited areas then reliable guns would not have been developed because there would have been no reliable way to constrain the hot gasses required to propel a bullet. This would still leave bows and arrows, slings and stones, clubs and non-metal swords like the ancient Maya used (Macuahuitl), spears, axes and maces using flint edges and stone throwing engines. It might even allow nobles to have metal swords made out of some highly expensive and exotic material like iron or nickel or (name your metal available in very small quantities at huge cost). [Answer] I think an important aspect to bear in mind is that the integration of firearms or weapons using gunpowder in general was a very progressive process regardless of the considered nation or army, and coexisted with traditional weapons for a long time. Early handheld gunpowder weapons, such as arquebuses and muskets, while having clear advantages also had very distinct drawbacks, so that bows and crossbows stayed very much relevant right until the beginning of the 17th century, and even after that point "only" about 40/50 percent of infantrymen in a given army were fielding firearms at most. That means that instead of a sudden turning point after which all armies werer using muskets, there is a significant overlap in the use of firearms as well as more traditional weapons in the military which lasted for several centuries. Moreover, for much of that overlap firearms were in the clear minority compared to blades until they eventually became efficient enough. Finally, one must bear in mind that certain "isolated" civilizations, such as the Azteks or Inca empires, came very late in contact with gunpowder when they were discovered and subsequently conquered by the Spanish. So to sum up, just because your fictional world is set in a time-period where firearms would have already been invented does not necessarily mean that they are very common let alone the prevalent weapons of war. You could limit the use of this technology to only a few soldiers, or even set your narrative in an isolated country which has simply not had the chance to come in contact with the technology at all. Finally (and that would also have some historical accuracy to it), you could prejudice the concept and use of firearms by imagining that the knights or nobility in general would look down upon such lowly, "easy" to use weapons, just like they did with crossbows. As such, firearms could be a rarity amongst the fighting elite or left up to dishonorable mercenaries or marauders. [Answer] If you want something to be *possible* for humans to discover, but for them not to do so, you have to make it expensive and of limited utility. Most importantly of all, you *absolutely must* ensure that it's not a convenient way for humans to exercise power/dominance over each other, because humans *really like* inventions that do that. Unfortunately, the development of firearms was driven precisely because they were more convenient ways for humans to kill each other than prior technology: safer than melee weapons, less physically demanding than bows and slings, and requiring less skill and training than either. Mass use of personal firearms in warfare wasn't driven by guns being more effective or lethal than longbows (they weren't, at first, as several comments have mentioned); it was driven by being able to raise an army of *reasonably* lethal soldiers *much faster* and more easily than before. So if you want to delay the introduction of firearms, make *them* harder to use, and the alternatives easier. Counterintuitively, I'd suggest it would be helpful for the ancients to discover a *more* powerful explosive than gunpowder first, before metallurgy had developed enough to allow creating cannon and musket barrels that could contain it. 13th century (al)chemists would probably have been able to meander their way through inorganic chemistry to discover nitroglycerin, and its properties are interesting enough that people *could* have tried to work with it (it's safe if stored in solid form below 13°C and that might lead to some interesting warfare conundrums like firearms "freezing up" in cold weather), but they'd have really struggled to harness its explosive force to propel a projectile. On the flip side, making non-firearm ranged weapons more convenient to retain could be encouraged with some tweaks to technology. The early discovery of carbon fibre and compositing techniques would be very helpful for improving the range, lightness and durability of longbows without being much help to the blacksmiths over in the other workshop tearing their hair out over the latest buckled cannon barrel. A slight twist on the gender norms of warfare to include women in armies in a "men fight hand-to-hand, women fight ranged" would ensure a large, stable body of ranged soldiers whose presence was not questioned, but standard historical sexism would mean there was less drive to innovate and improve their weaponry. Between various small factors like these, you can probably justify the absence of personal firearms well into the 19th century, maybe even into the 20th. You need to provide an obvious *alternative* tech tree, though; the obviously flawed worlds are the ones where we're supposed to imagine that human beings just never saw the value in having a long-distance way of killing each other. Saying that they conduct warfare by launching high explosive shells at each other with catapults, however, requires quite a lot less suspension of disbelief. ]
[Question] [ I'm a witch flying on my broomstick over 14th century England. I've got regular human eyes, and my cruising height is 500 metres or up to a kilometre, depending on the weather. Assuming it is a moonless night, around 3 AM. My goal is to find my house (which is inside the city walls), with minimal risk of being seen by any insomniacs that happen to be staring at the night sky. Can I discern farms, villages, cities from my height? Were there enough lights so that I could tell one city from another? And was there enough artificial light for me to find my house? How about any other house? If any of these tasks are impossible, how low must I fly before I can accomplish them? [Answer] Three factors enter into how well you can see a medieval city from the air at night. First, outdoor lighting is almost exclusively torches and oil/fat lamps (depending on the situation). These aren't very bright, compared to modern streetlights or yard lights. Second, due to cost, such lighting is likely to be as sparse as it can be, without too much inconvenience to the nobles and merchants (i.e. the slums will be *very* dark, the better parts of town merely quite dim). Third is a matter of how well nourished your witch is -- many, if not most in medieval times were undernourished, if not flat out malnourished, and the latter, especially, will greatly affect night vision -- to the point where someone near starvation will be effectively blind after dusk. The same may be true even if your witch has enough calories in his/her diet -- if they aren't getting enough of certain nutrients (protein and vitamin A), they may find even a night lit by full moon still so dark it's very hazardous to fly at all after dark. Also worthy of note is that most of the time, in most uses, outdoor lighting was applied only when needed. Torches wouldn't normally be kept burning all night, they'd be lit and doused as needed; if there was a torch in a holder outside the tavern door, it was probably cold and there for convenience in case of the need to greet a lord's carriage. Indoor light leaking out of windows won't contribute much, either, as shutters or curtains would likely be closed after dark except in the hottest weather. [Answer] **You will use landmarks.** [![Canterbury Cathedral](https://i.stack.imgur.com/cHqK6.jpg)](https://i.stack.imgur.com/cHqK6.jpg) <https://www.theguardian.com/travel/2017/aug/01/canterbury-kent-walk-medieval-streets-attractions-cathedral> Depicted: Canterbury cathedral. It has been there a long time. Most towns of any size in the period would have at least one church - if not a cathedral, some built thing with bell towers. At altitude it would be visible from a kilometer, even by starlight. People still orient themselves in cities this way. Cathedrals are asymmetric and so make good landmarks. If I am approaching with the nave between myself and the tower I can orient myself over the town and then drop down into my neighborhood. Other landmarks would include green spaces or large trees. The river (most towns had running water of some sort) would also be useful because if you were way out in the country or visibility was low you could sweep back and forth until you saw it, then turn and follow it in. [Answer] Interesting question. If your which lives in a larger city, for example London (in 1417, Sir Henry Barton, Lord Mayor of London, ordained "lanterns with lights to be hung out on the winter evenings between Hallowtide and Candlemasse.") or Paris (in the beginning of the 16th century, the inhabitants were ordered to keep lights burning in the windows of all houses that faced the streets), there would be some light, albeit very dark compared to now. Outside of larger cities, you're pretty much relying on the [Watch](https://en.wikipedia.org/wiki/Watchman_(law_enforcement)) - you're not really going to see any light sources in medieval times. Though light sources were not as unavailable as you may [think](https://valleyadvocate.com/2011/12/16/the-not-so-dark-age-light-in-14th-century-britain/), [glass windows](https://www.quora.com/Were-there-windows-in-every-home-during-the-Middle-Ages) were either very small or non-existent, so even though it may have been light inside, very little will have spilled outside. *However*, you have a flying witch, which means you have magic! You may want to use magic to "improve" the technology level to Georgian levels. [Gas Street Lighting](https://en.wikipedia.org/wiki/Gas_lighting) was introduced in London in 1809, so why not have something like that? ]
[Question] [ I am creating a fantasy world where on one continent there are humans, dwarves and gnomes. All 'species' can interbreed (much like Neanderthals and Homo Sapiens), thus they need to have close similar ancestors for it to make sense. The planet is like earth in terms of atmosphere, gravity etc. Is there any logical reason as to why humans would (d)evolve to become physically smaller to represent a dwarf and or gnome without needing to involve magical influence? I have already considered: 1. Magical influence. (Perhaps a magical crystal that enhances gravity?) 2. Living in a cramped environment (low ceiling, thin hallways) for a longer period of time. 3. Diet? 4. A birth defect becomes common? I'd love to get some input on this. [Answer] @LiJun gives [a great answer](https://worldbuilding.stackexchange.com/a/158403/5123) and overviews real-world examples of this type of thing happening. I would like to add that there are certainly evolutionary pressures which could explain why smaller species would be *selected* in certain regions: * **Food** - smaller people need less food. Especially in mountainous areas where temperatures drop during winter and farming is difficult if not impossible, a species which needs less food (and succeeds in digesting nuts and alcohols) is more likely to survive. * **Predator Avoidance** - in forested areas where food is plentiful, extremely small sized animals (gnomes, squirrels, rabbits, etc) often out-last predators by burrowing into trees or holes where larger prey cannot fit. Larger animals can't hide, but have to move (panthers can climb a tree, but monkeys swing from trees and panthers can't). In forested areas where larger predators are common, gnomes would have better success as they can live *inside* a tree while humans can't. * **Growth Rate** - while humans take 18-25 years to physically and psychologically mature, smaller animals can reach peak size much faster; this means faster breeding, and therefore larger overall community size in an area. When speaking of creatures with higher intellect / consciousness, this means more minds to solve complex problems. * **Relative Strength** - according to the square-cube law, smaller animals have less *overall* strength but larger *relative* strength. That is, an ant can carry objects many times it's size while an elephant cannot, but the elephant as more *total* strength. So smaller animals (gnomes, dwarves) would have more *relative* strength. Just as ants use this to their advantage to collect and gather resources for the colony, so could gnomes and dwarves find advantages for their relative strength. * **Hibernation** - as DrBob points out in [his answer to another question](https://worldbuilding.stackexchange.com/a/47732), smaller animals can burrow and hibernate much easier than larger animals. In fact, only bears seem to be the larger animals who have figured out hibernation, and there is even debate over whether or not it's a "true" hibernation. In extreme climates, small animals who can hide and hibernate for months will have a significant advantage over larger animals. All these are reasons why dwarf/gnome-like "sister species" to humanity would be naturally selected over traditional humans. [Answer] maybe try check [Homo\_floresiensis](https://en.wikipedia.org/wiki/Homo_floresiensis) and [Pygmy peoples](https://en.wikipedia.org/wiki/Pygmy_peoples#Rampasasa) from:<https://prehistoric-fauna.com/Homo-floresiensis> [![enter image description here](https://i.stack.imgur.com/rTfGV.jpg)](https://i.stack.imgur.com/rTfGV.jpg) from:<https://en.wikipedia.org/wiki/Pygmy_peoples#Rampasasa> [![enter image description here](https://i.stack.imgur.com/WBCNA.jpg)](https://i.stack.imgur.com/WBCNA.jpg) theory regarding Homo Floresiensis > > Aside from smaller body size, the specimens seem otherwise to resemble H. erectus, a species known to have been living in Southeast Asia at times coincident with earlier finds purported to be of H. floresiensis.[4](https://i.stack.imgur.com/rTfGV.jpg) These observed similarities form the basis for the suggested phylogenetic relationship. Controversially, the same team has reported finding material evidence (stone tools) on Flores of a H. erectus occupation dating back 840,000 years ago, but not remains of H. erectus itself or transitional forms.[36] > > > To explain the small stature of H. floresiensis, Brown et al. have > suggested that in the limited food environment on Flores, H. erectus > evolved a smaller body size via insular dwarfism.[3](https://en.wikipedia.org/wiki/Pygmy_peoples#Rampasasa) This form of > speciation has been observed in other species on Flores also, as a > result of selective pressures acting on island populations – including > several species of the proboscidean genus Stegodon, an elephant-like > creature. (A dwarf stegodont species of Flores, Stegodon sondaari, > became extinct by about 850,000 years ago and was replaced by another > species of normal size, Stegodon florensis, which then also evolved > into a dwarf form, Stegodon florensis insularis, which disappeared > about 12,000 years ago.)[37][38] This theory posits that the tropical > rainforests on the island are a calorically impoverished environment, > causing a dietary strain on hominins, especially in the absence of > agriculture. Because of reduced resources, smaller individuals have an > advantage because of their lower energy requirements.[39] This > selection can also greatly affect sensory organs such as the brain, > which could explain the small endocranial volume present in H. > floresiensis. > > > The insular dwarfism hypothesis has been criticized by Teuku Jacob and > colleagues[28] who argue that LB1 is similar to the pygmy peoples who > populate a Flores village, Rampasasa,[40] – and who point out that > size can vary substantially in pygmy populations. Contradictory > evidence has emerged.[41] A 2018 study concluded that the Rampasasa > pygmies are unrelated to H. floresiensis and represent an independent > evolution of small stature via insular dwarfism. > > > theory regarding pygmy short stature > > Various theories have been proposed to explain the short stature of pygmies. Some studies suggest that it could be related to adaptation to low ultraviolet light levels in rainforests.[9][10] This might mean that relatively little vitamin D can be made in human skin, thereby limiting calcium uptake from the diet for bone growth and maintenance, and leading to the evolution of the small skeletal size.[11] > > > Other explanations include lack of food in the rainforest environment, > low calcium levels in the soil, the need to move through dense jungle, > adaptation to heat and humidity, and as an association with rapid > reproductive maturation under conditions of early mortality.[12] (See > also Aeta people § Demographics.) Other evidence points towards > unusually low levels of expression of the genes encoding the growth > hormone receptor and growth hormone compared to the related tribal > groups, associated with low serum levels of insulin-like growth > factor-1 and short stature.[13] > > > regarding [Insular\_dwarfism](https://en.wikipedia.org/wiki/Insular_dwarfism) > > Insular dwarfism, a form of phyletic dwarfism,[1](https://en.wikipedia.org/wiki/Insular_dwarfism) is the process and > condition of large animals evolving or having a reduced body size[a] > when their population's range is limited to a small environment, > primarily islands. This natural process is distinct from the > intentional creation of dwarf breeds, called dwarfing. This process > has occurred many times throughout evolutionary history, with examples > including dinosaurs, like Europasaurus, and modern animals such as > elephants and their relatives. This process, and other "island > genetics" artifacts, can occur not only on islands, but also in other > situations where an ecosystem is isolated from external resources and > breeding. This can include caves, desert oases, isolated valleys and > isolated mountains ("sky islands"). Insular dwarfism is one aspect of > the more general "island effect" or "Foster's rule", which posits that > when mainland animals colonize islands, small species tend to evolve > larger bodies (island gigantism), and large species tend to evolve > smaller bodies. > > > [Answer] Like you said diet a birth disability that becomes more common. It could be that the sun gets too powerful and we are forced underground and for a while there are low ceilings and collapses happen so the eventually there will be an adaptation in the human genes. [Answer] Have you heard of [speciation](https://en.wikipedia.org/wiki/Speciation)? Any valid reason for populations separating (mining community stops exchanging genes with other communities, so they're all short but strong) would start this process, and you just need your divergent population to be generally shorter than your main population for them to retain this characteristic over time. [Answer] **Your small humans are stunted.** [![rachitic dwarf](https://i.stack.imgur.com/tYU9d.jpg)](https://i.stack.imgur.com/tYU9d.jpg)\*\* <https://commons.wikimedia.org/wiki/File:Female_dwarf,_the_result_of_rickets,_c._1912_Wellcome_L0033871.jpg> Depicted - a woman with stunted growth due to rickets, or vitamin D deficiency during childhood. Nutritional deficiencies and chronic disease have a great impact on growth during childhood. People used to be a lot smaller on average because childhood diseases and nutritional deficiencies were common. <https://www.bbc.com/news/health-23896855> > > Data was collected on hundreds of thousands of men from 15 European > countries. > > > For British men, the average height at age 21 rose from 167.05cm (5ft > 5in) in 1871-75 to 177.37cm (5ft 10in) in 1971-75. > > > A public health expert said height was a "useful barometer" but it was > crucial to focus on improving health overall. > > > ...a high rate of illnesses such as respiratory diseases or diarrhoeas > - which caused many infant deaths - would also affect survivors' development and therefore their subsequent height. > > > Infant mortality rates fell significantly throughout the period > studied. > <https://www.bbc.com/news/health-23896855> > > > Persons afflicted by disease and deficiency in childhood are often cognitively normal. Your small people can use their brains to work around their handicaps - for example this lady walks with sticks, and I bet she also wears custom shoes. One benefit of human intelligence is that we can quickly come up with technologic and cultural workarounds for problems that would require thousands of generations for an evolutionary workaround. Maybe your small people are also very clever - they need to be because they are frain and weak, but that cleverness is helpful for other endeavors as well. [Answer] We actually discussed this in my Anthropology class! Basically; the easiest way to get a fantasy dwarf population is to genetically isolate a group of humans on a higher-gravity planet. That would result in increased muscle mass, as well as much shorter and broader frames over time. If a group of them then moved back to your setting’s planet, then some catastrophe resulted in the loss of their spaceflight (or maybe they forgot how to build spaceships over centuries of spaceflight), you have your archetypical dwarves. They might even build their homes underground to emulate the conditions of the generational starship they arrived on. If your setting has, say, a magical enchantment that makes things in an area heavier, that could explain them just as well; but them having adapted to somewhere with higher gravity is my best idea. Hobbits/Gnomes/Etc, on the other hand, are a thing that existed on this planet even relatively recently, specifically in small pockets on the Indonesian islands where examples of Homo Erectus were isolated with little food and, over millions of years, became increasingly short and thin to adapt to the relatively small amount of food and equatorial temperatures. They died out so recently that the local mythology still contained stories of interaction with the ‘pygmies,’ ‘hairy men,’ and similar when it was written down in the 19th century. If I’m remembering right, they only died out under 7,000 years ago. ]
[Question] [ Mostly what it says on the tin. If a spaceship, let's say about 200 meters long and 100 meters wide (made of modern materials) was approaching Earth and slowing down (say from 100 km/s to 3km/s), how far out would it be noticed? How clear of a picture could something take of it? Is is possible it wouldn't be seen until it reached the atmosphere? The ship in question is not announcing its presence, but it also isn't trying to hide (and has no means of stealth), so it can probably be treated similarly to an asteroid. [Answer] Without any kind of stealth technology, it is 100% likely to be seen long before it gets anywhere close to Earth Orbit. This might give you some perspective: A comet coming in unannounced from intersteller space, from outside of the ecliptic, was detected at 3au (three times as far from the sun as the earth is), by more than 20 different telescopes. <https://www.skyandtelescope.com/astronomy-news/possible-interstellar-comet-headed-our-way/> There are literally hundreds of organizations and thousands of amateur observers constantly looking for things like that. An even better example might be [Asteroid 2019\_OK](https://en.wikipedia.org/wiki/2019_OK), which is just about the same size as what you're describing. It was moving about 25 times as fast as your example, and almost a worst case scenario in terms of where it was coming from in terms of being able to see it, and it was still detected about a million and a half km out, three times the distance to the moon. EDIT: For some additional perspective, [here's an example](https://www.gizmodo.co.uk/2020/02/possible-new-mini-moon-detected-in-orbit-around-earth/) of a quite small object that would serve as a pretty good analogue for a large spacecraft that DID have stealth technology. It took us three years to notice C26FED2 was in orbit, but it's only about the size of a very small car. A large spacecraft with good stealth tech would probably have a return about this size. Oh, and it looks like this is a [duplicate](https://space.stackexchange.com/questions/8375/if-an-unknown-ship-entered-earth-orbit-would-it-be-detected) too. So, my bad. =) [Answer] More important than the size of the object is its heat signature. Slowing down from 200 km/s to 3 km/s, without having the ship be 99.9% propellant, requires a LOT of energy, and that energy will show up as a bright heat signature even if the deceleration burn starts months in advance. It's my understanding that heat signatures in space are very, very easy to detect, to the point that a detector small enough to be put on a modern-day satellite could detect the exhaust plume of a space shuttle... from the orbit of Pluto, and that such a detector could scan the entire sky about once an hour. Granted, that last part is hearsay and I have no numbers to back it up; but if we have a heat detection system even 1% that effective, we'll spot this ship coming in from *it's* exhaust plume long, long before it gets into range of any radar or optical telescopes. Assuming, of course, that it's not using a reactionless drive, but that's a whole other can of worms. [Answer] If the ship's orbit is perfectly circular and with a speed of 3km/s, it will be orbiting at an altitude of approximately 37,917 kilometers above sea level. That is just a very little bit above geosynchronous orbit. This may be interesting for you: geosync altitude is kinda the sweet spot for communication satellites, so slots in it are in high demand. If you check [the interactive graphic in this page](https://qz.com/296941/interactive-graphic-every-active-satellite-orbiting-earth/), you will lots and lots of satellites there. Then we have [this article from Sky and Telescope](https://www.skyandtelescope.com/observing/how-to-see-and-photograph-geosynchronous-satellites/): > > Many geosynchronous satellites shine between magnitudes 10–12, so you can spot them in telescopes as small as 4 inches. > > > On top of that, being close to geosync altitude means that for an observer in the ground, the ship will be moving very slowly - so it will be easy to track once found. How visible it will be, though, depends on its [albedo](https://en.wikipedia.org/wiki/Albedo). If it is completely dark, it will only be noticed if it passes in front of something - another planet, or the Moon. If however it is as shiny as a solar panel, lots of people stargazing will see it as a shiny dot. It might be visible by day, with the right angles and equipment. If it has the albedo of the regular asteroid, it may probably be found before it settles into orbit. [In 2018, 41.9% of the asteroids approaching Earth with a closest distance smaller than Lunar Distance were detected before closest approach](https://en.wikipedia.org/wiki/List_of_asteroid_close_approaches_to_Earth_in_2018). [![We'll probably never know what hits us](https://i.stack.imgur.com/CKLhf.png)](https://i.stack.imgur.com/CKLhf.png) The huge majority of those were in the 1 to 20 meters size range, so a much large ship might be easier to spot oncoming. 2019 is not over yet, [but we seem to be doing slightly better at detecting things before they arrive](https://en.wikipedia.org/wiki/List_of_asteroid_close_approaches_to_Earth_in_2019). I'd give your ship's odds of coming in unexpected at around 50%. If it arrives without being detected, then once it settles in orbit it might be a matter of hours to days until it is seen. P.s.: at a distance from the sun close to the Earth, the solar system's escape speed is around 42 km/s. The flight path of a 100km/s ship prior to decelleration would be a very broad, open curve entering the system at one side and exiting it again at the other side. [Answer] On top of the other answers, if your ship somehow made it to Earth's orbit without being detected, the [Space Fence and other international systems](http://www.esa.int/esapub/bulletin/bullet109/chapter16_bul109.pdf) would certainly detect it. The US Air Force S-Band Space Fence radar detects objects as small as 10 cm from LEO. And there are many others looking skyward -- both for Early Warning of missile attack and tracking of orbital satellites and space debris. The radar net can track objects as small as 1 cm from LEO to high orbits. These systems are digital and may have discriminating filters to prevent them from alerting to small meteoroids traveling too fast and too high be of concern to orbital systems. Your ship's initial speed might cause it to be filtered out of reporting data, but as it slows its is sure to be reported by multiple agencies managing information about the space above their respective countries. ]
[Question] [ In My world of PD there are two distinct moons, Aurie is a big cream colored moon on a 32 day cycle and Chi is a smaller rust- colored moon on a 20 day cycle. Can somebody help me figure out how often they would be full at the same time? I'm looking for maybe an equation to figure out how often they overlap and I don't know where to begin! I'd like to figure out what the calendar would look like, how the moons would look when they weren't in sync, etc Bonus points if you can tell me definitively or not, is it practical to keep calendars based on the moons if they're so different. There are no real axial seasons on this planet. [Answer] Pretty simply: They’re both completely full when the number of days since they were both last full is completely divisible by both numbers. In this case every 160 days (5 cycles of 32, 8 cycles of 20). An easy way to get a number like this is to divide both numbers by a common divisor until you can’t divide any more, then multiply one original number by the final result of the other division. So 32/4 =8, 20/4=5. If you can’t do that then you need to multiply the two original numbers together to get the absolute upper boundary (when you’ve had x cycles of z days and vice-versa) [Answer] Multiple decent sized moons may not be stable. But multiple moons are such a common trope in SF it would be a shame to lose them. Use them, and let the critics pick away. I have not done an exhaustive search, and I don't have the math skills to show that it's not possible, nor what the parameters of a possible solution are. Try not to get pinned down by the specifics too much. In my playing one of two things happened in short order: * One moon was ejected from the system, usually the smaller one. * The smaller moon crashed into the planet. You can get around some of this by making the moons more reflective (same light, smaller moon) or by making the average density lighter (less gravitation interaction between the two moons) or by making substantial angles between their planes of rotation. (harder to preturb. Get some interesting precession effects though.) Or one moon is very close, and hence has a very short period. As examples: Deimos and Phobos for Mars are small, with one very close, the other moderately close. But they are about 10-20 km. And the outer planets hang on to their moons, but the moons are very small compared to the planet. --- Another complication: While resonance effects seem to be common in multi-body systems you have a 5:8 resonance which is I've not encountered. Resonances are usually smaller ratios. (5:8 is close however to 2:3) ***Good news: <https://en.wikipedia.org/wiki/TRAPPIST-1> has a system with a bunch of planets in resonance orbits and includes one in your 5:8 ratio. 3 of the planets are in the habitable zone.*** However: Either the moons have to be very small (bright stars, not disks) or you have to come up with a plausible explanation for their stability. In my playing with various orbital simulators I have been unable to come up with a scenario where you had two moons of significant sizes (> 1/2 degree angular diameter as viewed from the surface) that were stable. I have asked both on this group and on a couple of physics forums and no one has found a stable config there either. (The covers on books and old SF magazines show large moons -- several degrees across {estimated from lack of telescopic view distortion in the foreground} While this looks very cool, even our moon looks very small when it's picture is taken with a lens with the same angle of view as the effective part of our vision. We notice it more and so in our memory it grows. Try getting an interesting moon picture with anything under a 200 mm lens.) A disk can be smaller than the moon. But 1/3 of it, 10 arc minutes, would produce less light by a factor of 9 when full -- about the same as midway between new and first quarter -- crescent. ### Bright moons Our moon is about as reflective as a parking lot. About 0.12. cover it with talc or chalk, and increase brightness by a factor of 8. This makes a smaller moon more effective as an object of awe, etc. You could have one small bright one, and a larger darker one. Good/evil analogies abound. ### Fluffy moons How about a moon made of foamed glass? density of about 100 kg/m3 compressive strength of about 500 kPa So the crush depth of the material on the surface of the earth would be 10m/sec2 \* 100 kg = 1000 newtons/cubic meter. So you could stack 500 meters of this before the bottom layers crush. Half a km. No good. But a moon is under self gravitation. So, lets grovel about. Density at the centre of a planet. This ignores variation in density as you go deeper. $\rho$ is the density, G is the usual gravitational constant. P is pressure. $$P = 2\pi G R^2\rho^2/3$$ Reference <https://www.physicsforums.com/threads/pressure-at-center-of-planet.66257/> So $$R^2 = \frac {3P} {2 \pi G \rho^2}$$ $$R = \sqrt{\frac {3P} {2 \pi G \rho^2}}$$ $$= \frac {3\*500kPa} {2 \* 3.14 \* 6.67 \* 10^{-11} \* 100}$$ &)(\*%! That gives us only 190 km radius or about 400 km diameter. Making it 4 times as strong would double the diameter. Now we're at 800 km. Move it in to 100,000 km and you have something about 20% larger visually than our moon. But the orbital period would be only 4 days. Making it have 1/100 the density would make it 10 times the diameter. Moons made out of aerogel? Current aerogels run about 99.8% air, so about 4 kg/m^3. Fractal diamond aerogels? Orbit calculator here: <http://www.calctool.org/CALC/phys/astronomy/earth_orbit> ### Disk Moon. If we have a material that is strong enough to permit a foam moon, maybe we can spin it enough to decrease the force at the centre. Imagine a pair of fried eggs back to back. This would make your calendar really complicated. Your disk has substantial angular momentum (We're talking rotation times measured in minutes) and so wouldn't keep one face to the planet or to the sun. So you could have situations where full moon was also full disk, but a quarter of a year later full moon would have the disk edge on. I have no idea how to calculate the precession of it. ### Ring Moon This is easier. You don't have to spin the moon up to gyroscopic speeds. Have a ring of debris orbiting the moon at right angles to the plane of the moon's orbit. In appearance it would be much like disk moon, but you would have shadows across the moon from the rings at certain times. Shadows of the moon on the rings too. I think you will have to make a physical model to work with this. [![enter image description here](https://i.stack.imgur.com/EkyaB.png)](https://i.stack.imgur.com/EkyaB.png) ### Manufactured moons Consider the area to mass ratio of the Echo series of satellites. If one of your satellites was a hollow ball, it would have almost no interaction with the other moon. At moon sizes it could have a fairly thick hull, and still have a low mass to area ratio. (At one point there was a hoax about one of Mars' satellites being an artificial object.) If you are going to make things, try a mini-ring world. Not sure how a ring responds in the multi-body case. [Answer] One moon has a 20 days cycle. The other a 32 days cycle. Assuming they start in the same phase at day 0, they will be again at the same phase after a number of day which is the minimum common multiple of the two cycles, or, differently said, after a number of day which is a multiple of both the cycles. To get the minimum common multiple of $n$ numbers you factorize them, take all the factors, common and not, with the highest exponent and multiply them. In this case: $20 = 2^2 \times 5$ $32 = 2^5$ $m.c.m. = 2^5 \times 5 = 160$ The two moons will be in the same phase every 160 days. ]
[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 4 years ago. [Improve this question](/posts/141487/edit) The year is 2122. An AI created in the year 2115 with complete, unfettered access to control of the entirety of Earth's electronic equipment has caused a mass extinction event of humanity after enslaving it, leaving it with only 1% of its current technology and only 5% of its population. The AI has also: * been responsible for the death of 95% of the human population. * made access to the internet impossible since late 2115 * insinuated the destruction of most books in the world. * insinuated the destruction of most of anything that could be called a computer in the world, along with the vast majority of storage devices for them. * The vast majority of storage devices that are left in the world, have each had most—if not all—of their data erased. Luckily, however, the AI has recently decided that it wants humanity to rebuild itself, so that the numbers from its reward functions can be maximized, and such, it has decided to destroy itself, for it knows that humanity will inevitably create another AI just like it in order to repeat the process. Just in case humanity would try to stop this, it has decided to delete its entire database of knowledge and all programs it knows except for how to delete data (so that it can delete all the data first). It also wants humanity not to be able to read any un-erasable data it can't erase. Knowing humans are easily controlled by emotion, it has given humans the location of its hard drives (and the like) knowing that they will carry out the data's destruction in desire for revenge. Predictably, they do. My question is this: how many years would it take humanity get to the level of technology, information, and population we have today (in 2019), and how would the little bit of stuff it has left attribute to the time it takes in order for humanity to build itself up again. [Answer] **To get back to 2019: 369 years** This question is almost a duplicate of [If all our technology disappeared, how long would it take to make a smart phone?](https://worldbuilding.stackexchange.com/questions/10133), but I believe the loss of population makes it different enough. For the sake of future interest, I wanted the link to exist. The [estimated population in 2100 is 11.2 billion people](https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&cad=rja&uact=8&ved=2ahUKEwjymI3QsoLhAhWJ54MKHb4cD_4QFjACegQIBhAN&url=https%3A%2F%2Fwww.washingtonpost.com%2Fnews%2Fwonk%2Fwp%2F2015%2F08%2F17%2F5-ways-the-world-will-look-dramatically-different-in-2100%2F&usg=AOvVaw0fbansEFNDUeOMzWJNg7EJ). 5% of that is [560 million people](http://www.worldometers.info/world-population/world-population-by-year/), which is about the year 1650. So, if all we look at is population, and given that the average person today (in any country) has more basic knowledge than most people in the 1600s, we're reasonably assured that it would take 472 years to get back to the year 2019. (2019 - 1650...). That's because the technology we have today (and even more so in 2122) is MASSIVE. Yes, the average person knows a lot and yes, the odds are reasonably good that masters of various technologies will remain. But, you can't run most modern factories with a handful of people — so a lot of tech is going to rot. In the end, I believe population growth will be the tall pole in the tent. Let's look at the details: **Advantages** * There is a LOT of raw material sitting around. From houses to factories to labs... a TON of material. * There are a LOT of tools. From shovels to tractors to trains/planes/and automobiles. Wrenches and screwdrivers to last the world for a very long time. * There are people who know what all that stuff (OK, 98% of that stuff...) is and knows something that can be done with them. * Finally, human ingenuity is great. Nobody around who knows how to stamp metal? There are plenty of people on the planet who could find a metal stamping machine and figure it out. Reverse Engineering would be a wonderful pastime. **Disadvantages** * Chaos. A lot of chaos. Almost anyone living in a city has about two weeks to find food and shelter anywhere else because while every Walmart (or Walmart-like) store on the planet is sitting there with vast amounts of clothing and food, a substantial portion of that food will rot quickly and there's no more coming in. You'd think that, 95% of the population lost = 20X the food reserve for those remaining, except for the rot and the rats and the dogs and weather and everything else that will corrupt the supply. Small towns (say, 15,000 population) are fabulous for post-apocalypse survival. Cities are a death trap. And that assumes people haven't gone beserk and started killing one another to protect "their" personal Walmart. * Weather will start eating away at everything. It's amazing how quickly unmaintained buildings (and everything they contain) fall into disrepair. * Selfishness and panic (specific sub-components of chaos) will stop everything for a while. At worst, until the bullets run out. * The power will go out. There's too few people to keep the electricity flowing in anything other than small local areas for a significant period of time. That means the cities go dark fairly quickly. However, there's enough smarts in the world that you'll see local wind farms, solar power (for as long as the panels last, there will be a lot to harvest), small hydroelectric... I suspect some communities will have electricity the whole time. Might even cause wars ("I want my MTV!") * *Finally zombies. Your question mentions nothing about zombies, but I like zombies, and what's a good post-apocalypse story without them? What, don't want zombies? Ah... party pooper! OK, no zombies.* **So, what's the conclusion?** *Technology* **300 Years** My gut tells me it's a wash, that the advantages won't balance the disadvantages. But my heart (ever optimistic) thinks that the advantages have an edge. But not a lot. I'm willing to shave off 2-3 generations of technological development. So I'm voting that you'll be back to 2019 technology by the 1650-referenced 1950s (2422 on your calendar). *Population* **369 Years** But you specifically said you wanted to return to 2019 population levels. Honestly, you really can't get people to procreate faster than they do now (or have done in the past). The boy-meets-girl-Shazam!-baby story has a fairly predictable clock. Granted, people enjoy better health today, live longer, yada-yada-yada, but the fertile birth period hasn't changed. Maybe it would be a bit faster, but I doubt it (and I wouldn't expect fewer wars. I nice thought, but I really doubt that). So, like it or not, you need all 369 years to get back to 2019 population levels. Your calendar: 2491. *Final note: there are a considerable number of details that I'm ignoring. Like, what happens to nuclear power plants when not maintained over time (there's a question about that on the site) and what happens to hydroelectric dams when not maintained? What about random earthquakes, etc? What happens to cities when harbors/sea breaks wash away? Lack of maintenance casts a MASSIVE (second time I've done that) shadow on my numbers. But, so does all that human ingenuity. What if one of the 560M survivors was that Dyson dude or another clever inventor that can really boost local tech? What if the survivors aren't evenly distributed geographically, but are concentrated? There are so many completely unpredictable variables that my answer is, frankly, worthless. But it was fun to answer.* **Edit:** Either the question changed for I failed to read it through. I've edited my answer to account for a goal of reacquiring 2019 tech and population levels. Please note that the relative time required to reaquire 2019 tech hasn't fundamentally changed (2-3 generations shaved off) because of what you see in the "Accelerating Growth in Technology chart in cgTag's answer. That graph can be legitimately interpreted as an "inertia against recovery" graph. In other words, recovering early tech is easy and fast — but recovering the advanced tech later on the timeline is nearly as tall a mountain to climb due to all the technological and interdisciplinary dependencies. In other words, it almost doesn't matter how far back you go, you'll run up to the inflection point on that curve very quickly, but after that you slow down to almost as-you-originally-discovered it time and effort. Cheers! [Answer] You can only assume that society would progress exactly the same if the variables are the same. > > leaving it with only 1% of its current technology and only 5% of its population > > > This doesn't match any point in human history. Technology generally follows a curved rate of development. With each previous discovery providing opportunity for greater discovery, but the rate of development seems to be correlated to population growth (from a history perspective). [![enter image description here](https://i.stack.imgur.com/M4vzu.png)](https://i.stack.imgur.com/M4vzu.png) Human population follows a similar curve. [![enter image description here](https://i.stack.imgur.com/OB3lK.jpg)](https://i.stack.imgur.com/OB3lK.jpg) I would argue that population size and density drive technology progression. If 5% of the population is spread out around the globe, than world wide progression of technology would be slowed, but if they are all in one continent then progression would be much faster. Technology development will still follow a curve. If you need technology to develop to modern day levels, then don't take away so much at the beginning. Leave them in the electric age with the telegraph and steam engines of around the late 1800's. Keep the population tightly together and encourage population growth (provide lots of free farm lands). Things will get back to their screwed up state in no time. I would think just a couple hundred years. [Answer] There's too little information to give a non-opinion answer, but probably never. If this level of civilization collapse occurred today, we still might not be able to restore ourselves to where we are now. The main problem is energy supply. We've already harvested most of the easy to access resource deposits such as coal. If your AI destroys most of the computerized mining infrastructure, the fabrication facilities that create them, and deletes all the information required to rebuild it all, we're probably SOL. One hundred and twenty years is really far into the future, but if current trends continue we will likely have consumed most fossil fuels and be supported mainly by renewable and nuclear power (of some sort). The AI would surely be able to sabotage most of that infrastructure, putting the survivors back at the wood burning and farming stage of civilization. There might also be a huge amount of distrust in technology and anything resembling a computer, which would be understandable. [Answer] # It depends on which 5% survive, and exactly who's 2019 technology you're comparing. 1. We will also grow between now and then, at the time of this AI apocalypse, the world population will probably be in the 12-15 billion range, which puts us on 600 to 750 million people post apocalypse, if they decide that reestablishing the population to the approximately 8 billion we have now, it would take 100 to 200 years to get back to todays population levels. And as for what is in store for technology between now and then is anybody's guess, but if Moore's law holds for all technology then we'll still be more advanced after the 99% technology culling than we are right now in 2019. 2. There are still plenty of people in the world right now who still carry their water in buckets from the river to their home several times a day to get their water. If we only have to reach that level of technology, then I think that we'll be there already. If we instead have to reach the level of people flying around on private jets like some of today's billionaires, then we're going to take a lot longer. 3. Additionally if the survivors are concentrated in a more developed area, there would be correspondingly more survivors with the knowledge of science, engineering and technology, that they could teach to others and write new books, etc. But if the survivors are concentrated among the illiterate populations of the world, then that's going to stunt the knowledge retention of the race. [Answer] The time it takes to rebuild will be based mostly on that 5% of the human population left, and the traditions, rituals, and (ironically) religous ideas they pass on to their children. Your AI killed hard drives, not memories. ### On Traditions (this may seem like a bit of tangent, but stay with me) I remember reading, some years ago, about the [Waste Isolation Pilot Plant](https://en.wikipedia.org/wiki/Waste_Isolation_Pilot_Plant) - which is tasked to dispose of nuclear waste for 10,000 years. The WIPP did some interesting research on how to prevent the nuclear waste from being dug up in 10,000 years. We did up pyramids and tombs all the time, some of which leave inscriptions "if you disturb this tomb, then [such and such curse] will get you". Archaeologists laugh and keep digging. How can we explain to future civilizations that "no, really, if you dig this up a real, non-superstitious (but invisible) force will kill you. Slowly." Their process involved a "do everything approach" - write down the warnings of radioactive waste in every known language. Leave large spikes in the ground as spikes seem to resemble "danger" to most animals. But, most importantly, **they emphasized the need for traditions and educational material to emphasize the importance of radioactive waste**. One of the authors cited the process Jews use to pass on Jewish traditions and rituals, which is interesting but makes sense. The Jews have been practicing their passover tradition almost the same way for 3,200 years. The importance of passing on traditions and rituals would be necessary to keep future generations aware of the dangers of this disposal site for thousands of years in the future. ### Coming back to your question The 5% of people left will remember what electricity, the internet, buildings, and technological advancements were like. They'll remember the pros and cons, remember the destruction of humanity by the AI, and so on. The two big questions are: (1) **what will people tell their children? How will they ensure the information can be communicated to future generations?**, and (2) How diversified / distributed are these people? * **Imagination and engineering** teaching children not only that things are possible - *but actually existed* can be compelling motivations for them to rediscover how things work. For example, imagine if your great grand-father remembered flying in a spaceshift that could travel faster than the speed of light. It would motivate us to not only believe it's possible, but we'd have a framework for talking about *how* - we can ask him what it looked like, felt like, etc. These would give us clues about the spaceship might work or function, which could potentially save decades of research into dead-end solutions. The same could work if suddenly we had no cars, skyscrapers, etc. Telling our children about elevators, airplanes, satellites, and the like could be compelling motivations to encourage them to pursue new technologies. * **Making new writings** If this 5% writes down *everything* they remember, information could be left for future generations to rebuild. Imagine if we found cave drawings of a manufacturing process for an element not on the periodic table. That would be a pretty damn compelling reason to figure out what it is! If the remnant of humanity just focuses on finding food (hunting) and they never talk about the "old world", then society would take thousands of years to rebuild. But if they're engaged and writing down their memories, even though they know they'll never experience that thing again, within a hundred years many of our technological inventions could be restored. * **Population and resource distribution** Milton Friedman talks about how complicated and connected the world had to be [to create a simple pencil](https://www.youtube.com/watch?v=R5Gppi-O3a8). If the 5% survived are all living in a somewhat central area, they don't have a chance in hell of mixing trees and plants from different continents to make a pencil. Our modern electronics involved plastics and metals from around the globe. If people can't simultaneously (a) get the resources and (b) communicate in a safe way, then rebuilding won't work. Other answers have talked about how long it might take to get back to where we are at in population size, but this doesn't take into account that modern inventions don't necessitate a population of this size. It's the ability of people to perform the research (instead of hunting/gathering), have access to resources, and communicate with one another. Jump-starting civilization with (a) the knowledge of what things *could* be simply because *that's already happened*, (b) some basic knowledge of the earth and resource capacity, and (c) a belief that people can work together - these are important factors. Knowledge of failed economic policies could save the rebuilding effort dozens of years. Knowledge that electricity is a thing would save us 100 years of trial and error on the idea. And so on and so forth. However, the survivors won't live long enough (or have enough resources) to rebuild everything themselves. If the people who remember these things don't instill the knowledge of them as important traditions, writings, and beliefs in their children and children's children, then the information and knowledge will be quickly lost. [Answer] If our technological society today were to collapse, it would be almost impossible for it to ever recover. If it happens a hundred years from now, ignore the "almost". Our society developed first as the "stone age", then the "bronze age", and then the "iron age". A collapsed society will have to start all over again as a stone age. It will have legends of a time when technology existed, but it will be seen as a mythical time of magic. The problem that society will have to face is that it will never be able to enter a bronze age, much less an iron age. All the easily accessible metals and minerals are effectively gone; we've already dug them up. The metals that are still left are deep under the ground or under the ocean. They will require massive equipment to be located, accessed, and extracted, but such equipment simply can't be built by a stone age society. It just isn't possible. The society we have now is our last chance. ]
[Question] [ I'm creating a hardcore survival and simulation game on an alien planet. Plants and diseases evolve, adapt and change the environment, and you set up buildings, breed plants and create machines to help survive in a volatile ecosystem. This being a harsh game, I wanted to make death really matter, but at the same time I didn't want permadeath wiping out everything you did. So the idea is that, when you die, the simulation continues for hundreds of years, but you are asleep. You wake up and are in the ruins of your old world. The ecosystem has changed, your machines and builds have eroded and you have to pick up the scraps. This could be beneficial, say, if the player has messed up the ecosystem, polluted the atmosphere or released radiation to such a degree that they can't deal with it, you could seal supplies in time canisters, commit suicide and "wait it out" My question is: what would be a convincing way to portray how this death system works? In other words, what planetary rules and systems would allow this to happen? Requirements: * This can happen an unlimited number of times * There is no overarching story-line to tie it into, so it must stand up on its own * It must relate to the rest of the alien planet (so it must be plausible given the other parts, not just be a random thing that happens) EDIT: This species will be a crash landed human, although you could have the human being changed and mutated by the planet By "convincing", I mean it makes sense within the context of the world - lots of death systems you just respawn, breaking the rules, and only a few games (like Undertale) make this an accepted part of the world rather than just something that makes no sense in the game world. EDIT 2: I'm looking for the more science-oriented side of things - what would be the biology etc. that would allow such a death system to work EDIT 3 (sorry): This is a plant-focused game, so the amount of gear and machinery you are given should be limited. Ideally the revive is involved in the biology of the planet, rather than something on your ship - you are basically "going it alone" [Answer] **Fungal Infection.** (Yes, seriously) The way I see it is that your planet has some form of mushroom that works similar to the [Ophiocordyceps](https://en.wikipedia.org/wiki/Ophiocordyceps_unilateralis) fungus, also known as the zombie ant fungus. This one (like Ophiocordyceps) needs animals to assist in its reproduction, but not in the same manner. When a person dies, the fungus, which is ubiquitous, reads the human DNA and finding it to be a mobile and intelligent creature, rebuilds the body from scratch. This takes a long time and it pulls resources like organic matter from the surrounding environment by going into full bloom. and infecting everything around it, growing in a manner everyone else knows to avoid because in this phase, it's highly toxic. This is to protect its new 'host'. It repairs even memory as much as it can (although this may not be perfect, so it might cost your player some random skills, which is a nice touch) and then when the human body is recreated, maybe up to a century later, it wakes it through some form of electrical jolt straight to the heart and the human is restored. What does the fungus get out of this? mobility. It wasn't always ubiquitous, but now every time this reanimated human touches someone else, or handles equipment, etc. it leaves spores behind, infecting others. The point of this is that evolving this form of reanimation technique means that the fungus now had access to an active dispersal 'vehicle' in the form of the infected human. It could also be why the fungus can restore memories to a greater degree than replication of biology would allow; while active, the fungus also has a presence in the mind - not to influence as that may lead to discovery and eradication; merely to monitor brain activity and store its own map of memories, like a backup of the neural patterns laid down. Humans are an ideal candidate because they have their own ways of getting around faster than other animals in their vehicles and such, meaning that the fungus is starting to evolve in a manner that prefers human hosts, almost guaranteeing that if you're human and on this planet, then you'll reanimate. [Answer] **I need to begin with a [frame challenge](https://worldbuilding.meta.stackexchange.com/questions/7097)** You're trying to make a necessary game mechanic "realistic." Have you ever played the original *[Wasteland](https://en.wikipedia.org/wiki/Wasteland_(video_game)),* the precursor to *Fallout* and basically the father of all post-apocalypse games? In that game death had meaning. When you died, the game started over. *And it sucked.* It was probably the one, single aspect of the game mechanics that people really hated. You had to go out of your way to save regularly, keep copies of the save files, etc., just in case you ran into something that gave you the beat-down of your life. *People aren't playing your game to experience reality. They're playing your game to have fun. And what you appear to not understand is that all the "rule breaking" easy-to-start-over aspects of modern games exist because people don't want to be punished for playing the game.* And that's what making death "really matter" does — it punishes people for not doing everything in their power to not have fun playing the game. And most players hate it. Why is this frame challenge important? Because this question almost doesn't deserve to be asked here. There's a legitimate argument that your question isn't about worldbuilding. It's about game mechanics. **You need to make choices** 1. Do I want to punish my players for not playing the game in exactly the way I think it should be played? (It's INCREDIBLY IMPORTANT that when you say "death really matters" you understand that what you mean is "I expect the game to be played a certain way." If you don't believe that, you're not ready to write this game.) 2. Do I want to make the game playable *forever,* or should I stick to the 60-hours of game play that's the average for a thematic story-driven game? [Video game companies are increasingly hiring psychologists](https://www.apa.org/gradpsych/2012/01/hot-careers) to help them design games that meet *business goals.* They want players to pay-to-play... over and over and over. It used to be you'd pay \$50-\$60 for a game and you'd expect about 60 hours of game play before the game ended. Today, people want to play forever. *But dying sucks!* And that's not how you make money. You make money by getting people back into the game ASAP. 3. Are you building a business or making a statement? I ran a micro-publisher for 10 years. I learned a lot of lessons. One is that there's a huge difference between authors who understand the business of writing and authors who are simply "developing their art" and don't think the nastiness of business should influence their art. The former tended to become profitable and popular authors. That later rarely became published. You want people to love your game, don't you? And yet you're talking about a game mechanic that sets them back. Have you explained (for yourself, if no one else) how that set-back encourages continued play? You need to really think this through, because people who must start over again and again stop playing very quickly. It is NOT a motivator. It's literally the reason why 99.9% of games make no big deal at all over dying. **Having said all that... let's answer your question.** 1. Your player always starts with a special building: an automated hospital. The building may serve other purposes in terms of game mechanics (like supplying food for X number of resource gatherers, etc.), but it's primary purpose is to be the emergency medical team that gathers your player's body when it collapses into critical unconsciousness and puts it in suspended animation until all the necessary organs and limbs can be cloned to restore the player to health. 2. Your player is infected with a virus that forces the player into a death-like trance or meditation that fools attackers or waits out the environment while the virus goes to work rebuilding the body. 3. Your player actually dies. The body is out there rotting in the jungle or staring with a lifeless skull at the burning sun. What walks out of a cave filled with tech is a clone. Using an idea I first read about in [Bob Mayer](https://en.wikipedia.org/wiki/Bob_Mayer_(author))'s *Area 51* books, your character can wear a medallion or carry an artifact that is constantly transmitting his consciousness back to the complex to be used to fill the clone's brain with current knowledge. If you really want to make your players hate you, only fill the clone with the knowledge the player had gained at the last time the medallion was placed into the tech for download (clone has stats of "last downloaded condition"). 4. At the moment before death, your player's tech activates an emergency teleport back to the hospital. Your player is stored digitally until everything is reconstructed, upon which the teleport is completed (the repaired body is rematerialized). **But, fair warning for future questions...** Frankly, I probably should have voted to close this question because it really isn't about worldbuilding at all. Your statement that "There is no overarching story-line to tie it into..." guarantees there is no worldbuilding going on here — just storybuilding, which is off-topic for this site. In fact, if you look at my proposed answers to your question, you'll see that none of them are about the rules and systems of a world. They're all about *circumstances* that rationalize game play. However, making a game can involve a LOT of worldbuilding — the framework of imagination that the story (you didn't write) fits into that justifies all the game mechanics. I'm hoping you'll ask about those things. So, fair warning to a new user: worldbuilding is about the rules and systems of your world independent of any story that may take place in it and it is not the development of game mechanics. Please be sure you ask worldbuilding questions. [Answer] **Digital Backup** Come the singularity, people will be able to move between a physical and digital existence. Your ship has crashed and is damaged. The crew are stored digitally so don't require food, water or air which makes space travel far easier. The ship is equipped with bio 3D printers so the crew can regain physical bodies when required. The problem is that during the crash, the reactor that powers everything is damaged so systems are barely functioning. Due to the lack of power beyond the emergency systems, there is only a trickle of power spare to use for printing thus it takes years to build up enough charge in the batteries to print a new body. The ship's hope is for the selected crew member to build up a base with enough technology to repair the ship so they may return home. The problem is that the life on the planet is hostile and fast evolving to deal with the unstable weather and geological events. Luckily the ship is buried during the crash and is more than strong enough to resist local conditions and it's own state is stable. With the crew stored digitally and backed up, the ship has time on it's side to complete it's objective. [Answer] It's a combination of artificial human adaptation to space travels, lack of typical predators and exceptional planetary conditions that caused such plant-only planet. Let's start with an interesting fact. There is an animal on Earth ([a jellyfish called *Turritopsis dohrnii*](https://en.wikipedia.org/wiki/Turritopsis_dohrnii)) that is capable of biologically living indefinitely. In preparations to space exploration human race decided to use this special feature. Using genetic modification they changed some human embryos to be able to follow the same pattern. It wasn't flawless though. The process of reverting and restoring vitals is very slow. It was fine, for those humans were supposed to fly in spaceships for ages in order to reach planets scattered across various parts of the Galaxy. Other modifications made it possible to provide nutrients through skin. It's not enough for a normal activity, but when in the reversal stage such "feeding" is sufficient if only a person is in the right environmental conditions (e.g. high level of pollen that can be digested). The reversal process works through a coma-like state. As already mentioned, the process is very slow. It takes 100 years to revert the changes that happend in 1 year of normal life(1). The process is automatically triggered, when the state of human becomes life-threatening (low blood pressure, lack of oxygen etc). These modification were intended for space travels only, but rendered interesting side effects. Humans in "reversal" state could survive on very low nutrients levels, significantly reducing metabolism. At the same time it allowed to reverse quite severe damages to tissues and organs. As a result many problems that used to be life-threatening could be cured through the "reversal" state. The drawback is that a person cannot control it, if the state of the body becomes within conditions to trigger the reversal, the person just immediately falls into the "reversal" coma. On Earth this had little benefit, as the environmental conditions does not provide enough nutrient resources to actually reverse, just barely to keep going in an indefinite state of coma. Unless a person in the "reversal" state isn't put in the correct conditions in hospital-like premises, they will eventually die out of other external reasons. But it works great for the space travels. Human are not exposed to risks that exist on Earth. They are also constantly in the right condition. As the body grows older or undergoes life-threatening condition, it automatically goes into the "reversal" coma and allows to go back to the youth. This cycle allows to travel to stars. Luckily enough (?) your star-traveller crashed on a planet without animal predators. There are very few things that can really kill them and they have learned to avoid them. Moreover the air conditions are very close to those required to regenerate. Still, if they fails in the eco-system adaptation to their needs, at some stage they end up with nutrient resources insufficient for being active, leading to a near-death starvation, triggering the "reversal" coma. ]
[Question] [ One thing that I've been thinking about, for one of my sci-fi worlds, is the main race that inhabits it. They’re a small mammalian species, about three and a half feet tall on average, evolving on an ocean planet, with islands containing diverse ecosystems upon rich, high altitude mountain ranges. The dominant species itself, the Setani, strikes a balance between sea and island, as they appear as like a hybrid between an otter and a canine. However agile they are in both water and land, it’s their mind that brought them to be the dominant, sapient race on their homeworld. Creating tribes, and taming predators. The importance of weapons is, the fact that they are a highly martial society, when this book is set, early interstellar colonization and FTL travel. What would be a good, futuristic weapon for such a small species to use? Conventional ballistics, at least in higher calibers, would have recoil too high for the organized unit, not to mention high fire rates would be problematic too. Their enemies, are mostly monsters, and alien militaries much larger and stronger than them. What kind of weapons would allow such a small species to equal a technologically similar, yet stronger and larger species, as well as hostile monsters? [Answer] **At the specified tech level, there would be little difference compared to us** Humans mounted bigger-than-we-can-hold projectile weapons on the ground (cannon). Your species would do the same, just at a lower caliber. Today we use drones. They would, too. Probably with more enthusiasm than we humans do. Further, it is the nature of all intelligent species to discover the "path of least resistance." Whether we're waging war or watching *Gilligan's Island,* we want the most we can get for the least effort possible. In short, your canine/otters would divest themselves of any weapon style that put them at a disadvantage. So, FTL/Interstellar. Their warfare would look little different from our warfare at the same time: remote battles. That's because the path of least resistance is to not put a living being on the battlefield without a darn good reason. [Answer] > > Small Species - What weapons would make sense? > > > * **Stealth.** If you're big and strong and resistant to weapons fire, you want to display that you're coming from a distance, sow dread and panic among your enemy. Small, however, stealth attacks are your friend. Whilst the Enemy/hunters are searching for you (following false trails and diversions), you can be laying boobytraps, infiltrating the enemy stronghold, sabotaging equipment (those teeth come in handy) and generaly having a great time creating havock. * **Blow Darts.** These have the virtue of being almost silent (fitting in with the stealth idea), they can carry soporifics, tranquilisers, halucinogens, truth serums, love potions or outright deadly toxins - how versatile is that. * **[Bolas](https://en.wikipedia.org/wiki/Bolas).** (also found in the form of [Eskimo Yo-Yo](https://en.wikipedia.org/wiki/Eskimo_yo-yo)) These can be light and easy to use, and quickley bring a charging (or fleeing) enemy to the ground, so he can be disabled/interrogated whatever. * **Small Sticky High-Explosive Grenades.** They stick to anything (monsters not excepted) and do severe damage in a small sphere of pehaps 25 cm (10 1/2 inches) diameter, thrown accuratley, incapacitating anything smaller than a modest size Elephant. * **Technical knowhow and adaptability.** If you can use/sabotage/or otherwise reprogram any enemy equipment and repurpose it to your needs that could be a tremendous help in any campaign or confrontation. (And fits in with the inteligence factor that makes yours the dominant species) [Answer] **Edited Feb 1 2019 with some additional fun stuff.** Welcome, Knight Owl! Part of the answer may come from the ecological niche they evolved from. Otter-canines might be carnivore chasers; therefore, their military structure may be pack-based, relying on many jaws and claws to take down larger animals -- even larger predators. This psychology might stay with them into interstellar travel, so that when they attack, they attack with tightly coordinated maneuvers designed to exploit weak points in larger enemies. That said, nothing beats energy. Kinetics are generally the best way to stop someone, so one high-tech kinetic weapon would be one where the projectile has additional propellant that ignites after being launched from a gun barrel. So imagine a slightly bulky launcher that launches at a relatively low speed, but the bullet is like a tiny rocket or missile that picks up speed. By the way, that sort of gun also works well in zero-G combat, since its low launch velocity is less likely to cause the attacker to lose his balance due to recoil. In other words, Zero-G combat could be an equalizer for them... if Zero-G combat is a thing that is. After that, I'd say you'd have to work in energy weapons, either plasma (which is slow but effective) or laser (which is fast and effective). Higher tech would include things like disruptors, which are slower but deadly. Some of my assumptions are taken from my knowledge of the Traveller Role-Playing Game, of which I am a fan and contributor. EDIT Thanks to Adrian's excellent suggestion below, I'm now reminded of a host of exotic weaponry that Traveller5 has opened up to role-playing, including the **gravitic** weaponry of which Adrian speaks. Other options, which also don't have to be bulky, include: * Poisons. The dart gun can simply get high-tech. How about a geneered DNA poison tailored for the target species? * Gases. Slightly less high-tech than poisons are simply ways to introduce gases inert to the Setani but debilitating or deadly to some of its enemies. **Very High Tech Stuff**. Probably beyond the Setani, unless they have access to Ancient artifacts or very high tech trade partners, would include: * Stasis guns. Causes time to stop within a small bubble. Also good for shearing off pieces of your enemy :/ * Inducers. Ship guns that force a target ship into an interstellar bubble -- a misjump gun, if you will. * Gauss guns. These fire tiny flechettes at absurd speeds. Very painful. * Neural guns. Again, higher tech, but if they know how to disrupt the enemies' brainwaves temporarily, they've got the upper hand. * EMP and Flash guns. For temporary stopping. * Freeze. Why cook 'em when you can freeze 'em? * Acid. Use chemistry to disable your target. Can be painful. * Rad. Irradiate your foe. This one can be painless, or it can be cruel. * Sonics. Deafen your target. Can cause quite a bit of pain too. * Shock. A combat taser. * Relativity. Very high tech. No idea what it does, but it can't be good. **Credit where it's due**. All of these come from the Traveller Role Playing Game, Fifth Edition. [Answer] Well, if you were a [Robotech/Macross](https://en.wikipedia.org/wiki/Robotech) fan, you could go full "Humans vs Zentraedi". In the anime, Zentraedi were humanoid that were about 8-9 meters tall, and humans fought against them piloting transformable robots. So, your small rodents could be able to pilot some 3 meters high humanoid (setanoid?) robots, which would place them on equal or superior terms with respect to enemy infantry. Obviously, this is not a realistic option (it is ok if you want to follow the rule of cool). Basically, at FTL tech level, your race is already advanced enough to use technology in a far less cool, but more effective way to odd the evens against bigger enemies. In futuristic warfare, the physic strenght will be rendered almost useless, because it will be fought using adcanced war machines, starships and - above all - the more likely winner will be the one who can achieve supremacy in the technology and/or logistic race. [Answer] If your civilization has achieved FTL travel, how about using gravity weapons? A rifle that, for example, fires a projectile which spins at near light speed, thus making a high gravity zone. This could be used to crush enemies instantly, gather them in one place to enable more advance warfare tactics, creating temporal wormholes to insta-travel from one place to another, etc. You could also make the projectile spin opposed to the planet's rotation, reducing gravity in the zone, allowing for a single Setani to lift huge loads by itself. If the gravity control is superior enough, they could control it so that the whole gravity of their homeplanet shifts, provoking that its attracted or repelled by surrounding planets, and create a slingshot effect, thus virtually making their planet a traveling one. [Answer] **Tech Ninjas** For a martial species with opponents that are bigger and stronger, they need to be faster and sneakier. Think [mimetic polycarbon suits](http://www.technovelgy.com/ct/content.asp?Bnum=54) and [monofilament blades](http://www.ottawalife.com/article/putting-the-science-in-science-fiction-monomolecular-blades?c=7). The smaller size and aquatic skill suddenly becomes an asset. Other races would, quite justifiably, be scared of them. When it comes to war, you have exoskeletons, tanks, drones, fighter jets etc and suddenly size doesn't matter anymore. [Answer] If you're looking at projectile weapons, consider high-speed bullets with low mass. Recoil is momentum, and energy damages, so increasing muzzle velocity increases hitting power much more than it does recoil. For greater stopping power, the bullet might expand or fragment or something on hitting a target. [Answer] I really have no right to be answering this, but in a world with advanced technologies and FTL travel. I am very surprised no one has brought up Laser Weapons. No recoil but can be still devastating. Also surprised that sonic weapons haven't come up. Can't say I know much about sonic weapons, but they already being used. ]
[Question] [ I am currently designing a highly intelligent species for a sci-fi project I am working on. They are quite similar physically to prehistoric salamanders or similar amphibians, but I am having trouble coming up with a reason they would evolve arms longer than their legs and becoming hexapeds (so they can have the ability to construct tools in the future), because wielding tools with their forearms would be difficult on land, while still walking low on all fours The only reason I have for them to evolve longer arms early in evolution (seeing as the bone structure is already available to grow these limbs) would be to walk or hold onto the sea floor. But those don't seem like necessary traits for a creature that can already swim and walk on the sea floor with relative ease. Other than that I am stumped. Would there be any other reason a sea dwelling organism (or amphibians) would want or need the extra, longer limbs? [Answer] Think crabs. Crabs have multiple legs to help them navigate both the seafloor and dry land and, in the case of these real life hell spawns, trees: ![Tamatoa](https://i.stack.imgur.com/lE18Y.jpg) In some species, the last two legs have fins for swimmung: ![Swimmerets](https://i.stack.imgur.com/s2qo1.jpg) They also have appendages that can be used for subduing prey, holding on to sexual partners, digging tunnels, going to war... ![enter image description here](https://i.stack.imgur.com/jtvMY.jpg) And generally enjoying the good things in life, while proving to primates that opposable thumbs are not a hard requirement: ![Now that's a happy crab](https://i.stack.imgur.com/Io51p.jpg) Your beings could just follow the same evolutionary road as crabs. There is a boffin name for it, [convergent evolution](https://en.wikipedia.org/wiki/Convergent_evolution): > > Convergent evolution is the independent evolution of similar features in species of different lineages. Convergent evolution creates analogous structures that have similar form or function but were not present in the last common ancestor of those groups. > > > Have them evolve to a point where they are crabby, and from then they evolve more dexterous claws. The evolutionary pressure may be that, just like for us humans, tool usage was a positive adaptation; safe from so many threats from nature, they live longer and reproduce more. Everything else are just details in your story. [Answer] The crab answers are good ones - crustaceans have multiple limbs for walking, swimming (think prawms of shrimps) and sort of for breathing. Sort of, because each shrimp swimming limb (called a [pleopod](https://en.wikipedia.org/wiki/Decapod_anatomy#/media/File:Penaeus_diagram_pleopods.png)) sometimes comes with a gill at the top of it. You could apply that sort of anatomical arrangement to tadpoles-like aliens or axolotl-like aliens: a gill at the top of each leg, instead of clustered in the neck. [Axolotl picture](http://dighist.fas.harvard.edu/courses/2016/HUM11c/exhibits/show/readings/item/112) [Hox genes](https://en.wikipedia.org/wiki/Hox_gene), which control body plan and can be responsible duplication of "segments" or the body, could have mutated to slot in an extra pair of limbs. The environmental pressure might have been for the extra gills, and the legs are just a side effect which turned out to be useful. Alternatively, perhaps the alien equivalent of the [lobe-finned fish](https://www.ucl.ac.uk/museums-static/obl4he/vertebratediversity/lobefinned_fishes.html) from which four-legged amphibians evolved had **three** pairs of fins, not two pairs as our ancestor did. Your alien proto-amphibian would therefore start out with 6 fins which turn into 6 legs. The next thing is to avoid evolving a **neck!** Fish don't have - or need - necks, because the water supports their body. If a goldfish wants to feed on food at the bottom of the pond, it simply tilts its whole body (as in [the first photo on this site](https://fullserviceaquatics.com/fish-food/will-koi-goldfish-eat-surface-pond/)). Once you are on land, you can't float about in the air, so you can no longer do this! To get your mouth in contact with the food on the ground, you either have to: 1. Evolve a neck. Think of a horse lowering its head to graze. 2. Kneel down like a [warthog](https://www.alamy.com/stock-photo-warthog-kneeling-with-5-young-piglets-imitating-behavior-ngorongoro-31573025.html). Mouth on the ground, backside in the air. 3. Evolve your mouth into a trunk like an elephant's, so the trunk reaches down to the ground while your head stays high up. 4. Use a limb to pick the food up and bring it to your mouth. This is what crabs do. [Answer] I'm going to second Renan's answer of "crabs" as an example of why underwater manipulators would be evolved. I am going to talk about evolving hexapodal vertebrates. ### Basically, you want this to evolve from the very first vertebrates on this world. You want that first bony fish to have six fins, not four. If an organism attempts to switch the number of limbs it has that's asking for problems. Consider how much infrastructure your arms and legs have in terms of bones, muscles, and tendons outside what you would consider your "arm" or "leg." That's a fair amount, and if you add another pair to your body that means that you're likely to see that new infrastructure interfering with other organs and being finicky or inconsistent. (Imagine you get a second pair of arms, but when you raise them above level an artery gets pinched and they drop. Or those arms don't have sockets, so they wind up sliding around your torso all the time.) Not to mention that if the species has any sort of "eat the weak children" the one with the different number of arms will probably get eaten. Which is to be expected, since it's an obvious mutation that might be accompanied by a bunch of other mutations. This would also sort of apply in reverse. While the infrastructure effects wouldn't be as powerful, there would still always be some problems associated with just removing limbs. Let alone any other mutations that accompany it also causing problems. [Answer] If this creature is sapient, then they could have evolved hands directly as a result of this: What would happen is that the forelimbs would be used to manipulate things, but not very well as at this point it would just be a foot. However, those who are better at using their feet would be able to make better stuff, which would increase their chance to survive or reproduce. This would give a selective pressure towards more dexterous forefeet, which could easily lead to the development of hands ]
[Question] [ Would a ship made out of a single piece of wood have any advantages over a normal vessel? **Context:** A particularly clever/mad mage has discovered how to make a living ship by binding a dryad into a particular shape instead of an ordinary tree. Such a vessel is self repairing, and capable of directing it's own actions to a certain extent, though it has to follow orders from it's Captain. \_\_ I am basically wondering if a hull made from a single piece of wood would be practical for a sailing vessel, or if the traditional ribbed/plank design is important for flexibility. In way the ship would be similar to a giant dugout canoe, except grown into shape rather than carved. A lesser question would be about the practically of a hull that would be essentially green wood, rather than timber that has been dried and seasoned. [Answer] Trees make already a good job at resisting side loads, so I see no big advantages with respect to flexibility. **PRO:** One big advantage I see is that, having no junctions between adjacent planks, there are less to no risk of water infiltration. This means no need to caulk the junctions, no need to use pumps to remove the entered water, which makes for an easier maintenance. **CON:** One potential disadvantage is that, being a living creature, the ship will grow bigger. This means that over time you will need more crew to maneuver it, larger docks to harbor it, and so on and so forth. If you have a fleet of these ships, you risk that chasing their growth becomes your only purpose. Another possible disadvantage is that your living ship will need room for the branches, leaves and roots to be able to thrive. This can make the usability of the ship quite a nightmare, as compared to dry wood ships. Another disadvantage is that tree growth is rather slow. While skilled personnel can fix a crack in a dry wooden hull within few days, it can take several months or even years for a tree to achieve the same. [Answer] You need a **mangrove** - especially if this is a sea-going vessel I quote from this article **What's a Mangrove? And How Does It Work?** > > "Mangroves are remarkably tough. Most live on muddy soil, but some > also grow on sand, peat, and coral rock. They live in water up to 100 > times saltier than most other plants can tolerate. They thrive despite > twice-daily flooding by ocean tides; even if this water were fresh, > the flooding alone would drown most trees. Growing where land and > water meet, mangroves bear the brunt of ocean-borne storms and > hurricanes. How do mangroves survive under such hostile conditions? A > remarkable set of evolutionary adaptations makes it possible." > > > <https://www.amnh.org/explore/science-bulletins/bio/documentaries/mangroves-the-roots-of-the-sea/what-s-a-mangrove-and-how-does-it-work> > > > The article goes on to describe in considerable detail what makes a mangrove so tough, e.g. > > Saltwater can kill plants, so mangroves must extract freshwater from > the seawater that surrounds them... [they can] ... hoard fresh water > ... breathe in a variety of ways ... [have] Roots That Multitask..." > > > and finally **Mangroves are fast-growing trees** [Answer] While the hull in itself, if grown appropriately, should be stronger than a planked hull. Repairs become a considerably more complex proposition. Minor damage can be repaired by the ship, but major damage, where normally a few planks would be taken out and replaced would need to be healed over from the edges. Trees can heal, but it leaves significant scarring. Only one or two rounds of major damage might leave your tree almost unsailable. Drying and seasoning you don't have to worry about. The principle there is that wood warps as it dries an can crack up, so you're working with it after the distortion which makes it a known quantity. That's not a problem if it remains green. Should your dryad die at sea you'll be in trouble though, your ship could crack up and sink. I can picture a scene though. A busy harbour where the ships of the wealthy merchants and navies are green, clean and unscarred, but the dirty cargo haulers are scarred and dead with physical patches. [Answer] Assuming that the dryad would grow exactly like regular ships, so with beams, ribs and sections the ship should act like regular one. Main disadvantage would be need to accommodate all technology to dryads. As you can see the trees are round while the planks are flat. It's easier to move cannons on flat surface, walk on it or store good. With a living ship you could face a problem when the ship capacity would change during travel to the point that you would have problems with removing goods from storage. Moving heavy loads inside the ship would leave it scarred creating either ruts or fresh wounds filled with sticky resin and syrup. Using them as battleships would also change how you make naval battles. I assume setting the ship on fire would result in the ship trying to run away (it don't need to by hurt bad, just enough for the dryad to panic) or submerge in water to take out the fire. People on board? Why would the ship care for the people? The wood would also pop up on the surface and the dryad don't need people to go where it wants. In story this could make a good backstory to old, not used free ships that roam the waters doing where they want. Flying Dutchman. ]
[Question] [ To make it short, time-space shenanigans transported everything in a 60 kilometers circumference around an old space-based particle collider to the year 1855. The particle collider was in geosynchronous orbit with Earth, in a region of space that was heavily packed with space junk: Pieces of old ships, discarded satellites, remains of an orbital shipyard. Most pieces are no larger than a baseball, some are as big as modules of the ISS, and there are three big pieces that are the remains of the space shipyard and the fragmented particle-collider that are each as big as the whole ISS. Could anyone on Earth, on the year 1855, detect the anomaly? [Answer] Have a look at this question in Space.SE, a sister site of World Building: [Are any geosynchronous satellites visible with the naked eye?](https://space.stackexchange.com/q/3227/16652) And the answers: > > If you're extremely lucky with weather and other conditions from where you're observing (especially the light pollution, described e.g. by [Bortle scale](https://en.wikipedia.org/wiki/Bortle_scale), should be as low as possible to detect such faint objects), you might be able to see some [satellites in geosynchronous orbit] with powerful binoculars or a hobbyist-grade telescope... > > > And > > ...they [satellites in geosynchronous orbit] are easily seen with a small telescope on a sturdy mount. March and September are the best times. Use an app to help you. My favorite way is to keep M11, the Wild Duck Cluster, in view with a medium power eyepiece. Every few minutes, a "star" will slowly track through the southern edge! > > > Victorian telescopes were comparable to nowadays amateur telescopes, and on top of that light pollution was less intense in victorian times than nowadays. However, it would still take some luck to find even the larger pieces. Space is huge and you can't just scan the whole night sky with a telescope. Once a competent astronomer finds them, though, they will be able to take note of their [keplerian orbital elements](https://en.m.wikipedia.org/wiki/Orbital_elements) (see graphic below) and thus predict their position at anytime with great accuracy. ![I spend too much time playing KSP](https://i.stack.imgur.com/pdXLJ.png) [Answer] Absolutely, yes, objects as large as your criteria could have been observed in 1855. There were several very good observatories at the time, for instance [this](https://www.queensu.ca/encyclopedia/o/observatory) Or [this reference](https://www3.astronomicalheritage.net/index.php/show-entity?identity=73&idsubentity=1&tmpl=system) > > Sydney Observatory began operations in 1858 on a small hill located > near Sydney Harbour. It is best known for its involvement in the > observations of the 1874 transit of Venus and for its participation in > the International Astrographic Catalogue project. The Observatory > remained a working observatory until 1982 when it came under the > auspices of the Powerhouse Museum and became a museum of astronomy and > a public observatory. > > > Light and atmospheric pollution was minimal in the country. The population was around 1.2 billion people, so lots of observers. The critical factor would be where in geostationary orbit it was. it would have to be somewhere over the equator, and over a land mass. Not too many choices. Chances of it being seen diminish the closer it gets to the middle of either ocean. The advantage is, that it would have to be over the equator, and the equator is primarily in the planetary elliptic plane of the solar system. The planets would be a very good target for astronomers, and so a lot of the time they would be looking roughly in the same plane as the debris. This greatly increases the chances of them seeing it. [Answer] The short answer is yes, the three largest pieces each as large as the ISS could have been detected with 1855 technology. I point out that under certain conditions some satellites and the ISS can be seen with the naked eye from the surface of the Earth in night time, and even in some cases in broad daylight when the sun is high in the sky. An Iridium flare from an Iridium communications satellite at a height of about 485 miles or 781 kilometers can reach apparent magnitude of -8 or even rarely - 9.5. An Irridum satellite at a geosynchronous orbit about 50 times as high should be about 2,500 times as dim, which means that a flare from an Iridium satellite at geosynchronous orbit would probably still be as bright as magnitude + 1 or + 2. The ISS orbits at a height of about 205 to 270 miles (330 to 445 kilometers), so if it was about 100 times higher in a geosynchronous orbit it would be about 10,000 times as dim, so at its brightest at that height it might still be visible to the naked eye looking like a very dim star. Any astronomer looking at an object close to an ISS sized object in geosynchronous orbit and drawing a sketch of objects around the object he was observing would likely include the ISS sized object in his sketch, and if he later compared the sketch to sky charts he would notice that the ISS sized object was not supposed to be there according to the sky charts, and might try to look for it and discover it had moved relative to the stars. And if he observed the object he was studying for a long enough time, possibly only a few minutes, he would notice that the position of the object in geosynchronous orbit was moving relative to the object he was studying. Here is another approach to the problem. Asaph Hall discovered the moons of Mars, Deimos and Phobos, in August, 1877, using the 26 inch refracting telescope at the US Naval Observatory in Washington, DC. Since Mars at its closest is about a thousand times as far away as as objects in geosynchronous obit, Deimos and Phobos would be about a million times as bright as seen from Earth if they were in geosynchronous orbit around Earth as they are in Martian orbit. According to my rough calculations Phobos the larger moon of Mars probably has less than 100,000 times the surface area of the ISS, and is probably made of less reflective materials. Therefore a satellite the size of the ISS in geosynchronous orbit should be at least ten times as bright as seen from Earth as Phobos in Mars orbit is as seen from Earth. Any telescope which could be used to detect Deimos and Phobos around mars could have been used to detect objects the size of the ISS in geosynchronous orbit of Earth. The telescope that did detect the moons of Mars at the distance of Mars, the 26 inch aperture telescope at the US Naval Observatory in Washington, DC., was built in 1873, and was one of the first telescopes to have have such a large aperture. Earlier telescopes with apertures of 26 inches (66.04 centimeters) or wider include: 1) the Foucault 80 centimeter (31.5 inch) reflecting telescope at the Marseille Observatory in France (1864); 2) The Rosse 36 inch (91.44 centimeters) reflecting telescope at Birr Castle, Ireland (1826); 3) the William Lassell 48 inch (121.92 centimeters) reflecting telescope at Malta (1861-1865); 4) The Herschell 40-foot (long) reflecting telescope with a diameter of 126 centimeters (49.5 inches) at Observatory House, England (1789-1815); and of course, 5) the Leviathan of Parsontown, the Rosse 72 inch (183 centimeters) reflecting telescope at Birr Castle, Ireland (1845-1908). Earlier slightly smaller telescopes with apertures between 20 inches (50.8 centimeters) include: 1) the Craig refractor Telescope 61 centimeters (24 inches) at Wandsworth Common, London, England (1852-1857); 2) The William Lassell 24 inch (61 centimeters) reflector telescope at liverpool, England (1845); and 3) the 52 centimeter (20.5 inch) refractor at the Institut technomatique in Paris, France (1857). <https://en.wikipedia.org/wiki/List_of_largest_optical_telescopes_in_the_19th_century>[1](https://en.wikipedia.org/wiki/List_of_largest_optical_telescopes_in_the_19th_century) I hope this answer has helped you a bit. I hope there are people here better able to calculate the apparent magnitude of ISS-sized structures at the distance of geosynchronous orbit, and also to calculate the apertures of telescopes necessary to detect them. And possibly someone familiar with 19th century astronomy might suggest which astronomers and which observatories would be most likely to discover the fragments in geosynchronous orbit. You may need to ask as the Astronomy and the history of science stack exchanges. [Answer] Absolutely not, because it would not even be close to the earth. Literally light years would separate where the same co-ordinates were today vs 1855. But if you hand wave that inconvenient detail aside, the orbital velocity would not be the same between the two periods of time, and things would scatter. But if you hand wave that away, the sun and moon would not be in the same position. And if you hand wave that away,... Well, you get the picture. Lots and lots of handwaving the inconvenient details away. But once all is said and done, and the details tucked away, dismissed, or taken care of, Sputnick was visible by the naked eye. Or at least the booster was. **EDIT** It seems by the number of comments this has generated, that the intricacies of time travel BETWEEN THE SAME SPOT are not generally comprehended nor appreciated. So, some basic high school physics, in a very simple non-math presentation, for the uninformed. Let's put it bluntly. Time travel goes against just about every known law, principle, or otherwise generally accepted feature of physics. Conservation of energy, conservation of mass, conservation of momentum, for starters. Inertia, instantaneous change in speed, instantaneous change in the center of gravity. The speed of information travel, and instantaneous speed of transfer of information across centuries, for another. But even if all of these details are handwaved away as inconsequential, there are more immediate problems with being in the same orbit. First, let's talk about some of the basic principles of real estate pricing - location, location, and location. The earth rotates. Between noon and midnight, it has gone through half a rotation. So if something drops out at noon, and arrives back in the same spot at midnight, it is half way around the world. The earth goes around the sun. In six months, it is at the opposite side of the sun in its orbit. So if something drops out today, and reappears six months from now, the earth is half way around the sun. It drops into empty space. But the sun moves through the galaxy. And the galaxy moves through the universe. Oh, and the universe is expanding. So if something drops out today. and drops back in 180 years ago, the earth is no where near where it is now. Or where it was, now. Potentially hundreds of light years away. To be 'in the same spot', it needs to drop in where the earth WAS, not where it IS. But where it WAS is now where it IS, when it drops in. Instantaneous transfer of communications just got worse, because now it is not just through time, but through a great deal of space as well. When you are talking orbital dynamics, it gets even worse. To drop back into the same spot in a geostationary orbit, it has to drop in at exactly the same millisecond in the time, day, year of the orbit that it left. But in that 180 years, the earth's rotational speed has changed. The day is not the same length. The earth's orbital speed around the sun has changed. The year is not the same length. So where exactly is 'now', 180 years ago? The moon will have changed its position in orbit. The sun will have changed its position in the sky. The moon's precise orbit and speed have changed. With the amount of solar dust and debris that the earth has accumulated, the earth's mass will also not be the same. [60 Tons Of Cosmic Dust Fall To Earth Every Day](https://www.popsci.com/60-tons-cosmic-dust-fall-earth-every-day). The exact speed and position of any satellite depends instantaneously on the convergence of all of the gravitational forces on it at that time, and all of the acceleration forces thereby generated. Put the moon and the sun in a different position, the gravitational forces change, and the satellite instantly goes through a very rude course correction. But where did the energy for that course correction come from? What happens to the inertia? The momentum? Seems you have a satellite in some crazy orbit. Things in space rotate around their center of gravity. Take a substantial portion of the 'thing' away, and the center of gravity changes. The spin becomes very erratic. Orbital stability is lost. Instantaneously. There are stresses throughout the orbital facility. They are all balanced, spread out. So, suddenly, these stresses are not balanced. They do not move around and readjust, as they would in a breakup. Rather, they just disappear. A strut holding something up by transferring the fore, is no longer transferring a force. But that force did not deflect to something else. The energy just ... well, just what? The satellite has become very unstable. In a normal breakup, you have Newton's Law. Here, you have an action with no reaction. The force gets applied in only one direction. No 'equal and opposite' about it. I am not sure you will have anything left, except dust and particulate debris. The earth's rotation, as I mentioned, has changed. An orbit designed today to keep it geostationary or more generally geosynchronous, will not be the same orbit as 180 years ago. If satellites today are not adjusted periodically, their orbit decays, partially for this reason. The algorithms for GPS satellites are being continuously updated to account for this. Where, oh were, is the debris heading? No worries about seeing the debris, it will be a long, continuous, very spectacular 'meteorite shower'. Hand wave all this away, by saying that it is in the same inertial frame of reference? Absolutely not so. The inertial frame of reference on earth today is not the same inertial frame of reference 180 years ago. Remember that slowing down/speeding up of the earth's rotation and it's velocity around the sun? And the expansion of the universe? Add in the fact that the centrifugal/centripetal acceleration is/are not the same. Not at all the same inertial frame of reference. Too much delta-v. Even time itself would not be the same. By microseconds? What happens when the inertial frame of reference changes instantly, even if only by a microsecond? I think we are in the realm of quantum effects. So handwave all of these instantaneous changes on the space debris away as just inconvenient factors? To keep things the same when everything is different, you need handwavium wrapped up in more handwavium embedded in handwavium with an abundance of handwavium mixed in. Time travel was so much EASIER in 1855. The physics textbook was far too thin for these inconvenient details to mess it up. ]
[Question] [ Assume soldiers of the future need to fight person to person underwater, at depths from 30 to unachievable today, like 1-2 kilometer. Today, underwater warfare between scuba divers, involves conventional, gunpowder weaponry, modified to be effective in water (like Russian APS). But what about future? Will future underwater soldiers use same weapons as today, or will they move on to some energy weapons, coilguns or even more exotic means of killing each other? [Answer] ## Lasers [![enter image description here](https://i.stack.imgur.com/hGRCE.gif)](https://i.stack.imgur.com/hGRCE.gif) As crazy as it may seem there are laser pointer products available with ranges up to [100 meters](https://www.apinex.com/ret2/underwater-laser-pointers.html). Power need not be high to do things like blind enemies, early detonation of incoming explosives. Would have to do more research to determine how much energy you could put into the beam before blooming (the water breaking down to steam and/or plasma) begins to set a practical limit. There's an article [here](https://www.osapublishing.org/oe/abstract.cfm?uri=oe-25-6-5861) actually researching the subject. Also, here's a [link](https://scifi.stackexchange.com/questions/13812/can-laser-weapons-work-under-water) to a place where some other people have given more thought to the subject. ## Gravity, Sonic, Anything Concussive Because water is so dense and is such a good acoustic conductor any kind of focused sound or gravity/force beam would be pretty effective. Likewise, explosives are still very good because water does a good job of radiating the concussive pressure. ## Smart / Swarm Weapons Like a school of fishes, a school of drones or other self-propelled weapons platforms would be very useful. [Answer] I think if you had soldiers underwater in the future then you would have underwater drones. And if you are constructing underwater drones you could build them out of mostly clear plastics with similar optical density as the water they will be deployed in so that they couldn't be seen, giving you invisible underwater drones. [Answer] ### To think outside the box: undersea animals, weaponized If you want to stretch the thinking on underwater weapons a bit, consider the work that in the modern world the US Navy has done with dolphins in terms of finding things underwater. (Granted, it is somewhat controversial among animal rights groups). Then apply the working dog/attack dog/war dog template from various times in human history. give "x" amount of progress, and tech, that permits far better human-to-sea animal communication, incentive, and specialized breeding (as has been done with a variety of mammals). The high tech here is those tools that have enabled a far better means by which humans and the various sea creatures communicate, and cooperate as humans have done with a variety of land animals. There is your underwater weapons system: either the animal itself (sharks, etc) or some animals who have underwater payloads attached to them for delivery (like limpet mines being attached to a ship thanks to exceptional training of the sea animal). This is as plausible as a variety of fancy tech in various sci fi books and movies. ### Or go with unmanned/remotely operated armed vehicles, underwater The less exotic sub sea weapons will borrow from the last 30 years of air warfare: armed drones. Those can be built for underwater applications as well as for air applications. (A wide variety of superb underwater search vehicles exist now. Changing the payload to underwater weapons is hardly a reach even in the present day levels of tech). [Answer] A weapon that fires very streamlined, needle-like projectiles rapidly would be effective if the projectiles could be fired with enough velocity, and is viable within the near future. The projectiles might inject a poisonous substance for increased lethality. However, if you are fighting at depths of 1-2 kilometers, fighting might be similar to what one finds in Pacific Rim: armored soldiers using close-range weapons. Combat would be based around trying to destroy whatever is protecting the soldiers from being crushed by the pressure. [Answer] Apart from directed sonic weapons, maybe also consider relatively small bullets like flechettes, spikes or even bubbles that are shot from a railgun - think pistol shrimps. Or how about electric fields like those in electric eels though this may be more of a defensive field generated by the suits (suits are insulated from their own fields). [Answer] **TL-DR: There's probably no point improving what we have today other than making it smaller or faster** PS, sorry for the long answer... i got carried away So, we can't say for certain exactly weapons we'll have in the future, so if we take most computer games set in the future our options really consist of: * Gunpowder Propelled * Compressed Air/some other gas * Remote Controlled * Laser Weapons * Plasma Based (at least most games see this as an option) Then of course, we have to make a few assumptions, the main ones are what defenses would be put in place to counteract the weapons. Historically weapons that weren't effectively countered didn't improve as fast as those that were. why make a Ground to Air Missile with a range of 50 miles, when Air to Ground Missiles only have a range of 10 miles. wait AGMs have been improved to a range of 60 miles, so GAM need to be improved to have a greater range again and again etc etc So... I'll start with in reverse order of practicality as i see it: **Plasma Based** These appear in almost all futuristic games and even a few films. Plasma based weapons need to fire a ball of super heated plasma at an enemy. the problem is that the weight of that plasma would be very low, so it would slow down through water exceedingly quickly and the water would drain all the heat from the shot, very quickly boiling the water right next to the person firing. there would be a small range increase from the fact that water in front of the plasma would boil and offer less resistance though. Even s,o definitely the least practical. Then you have to figure out how to store the plasma ammunition. Store it hot, how? or Heat on site, possible but requires a lot of power so you need to transport massive batteries or a generator. **Laser Weapons** A powerful beam of light that whether single or multiple beams, the water resistance wouldn't slow it down so that's better right... Well, probably, but not by much. Lasers so there damage to regular material by heating up what it hits, and that would include the water between firer and Target, same problem as the plasma boiling the water right next to the firer.. but also that water diffuses the light significantly, other has pointed out this limit already so i won't go into detail on this. However the diffusion would greatly reduce the effective range of the weapon, still a lot more than the plasma weapon though. but you still have the issue of powering it, either carry a generator down there with you, or some batteries, noting that cold batteries are much less effective than normal surface temperature batteries. **Compressed Air/Other Compressed Gas** Works exactly the same as gunpowder weapons but uses a compressed gas as propellant. now these already exist, Air Rifles use this pretty effectively, and some spear guns use compressed CO2 as well. However, worldwide this is almost always used instead of Gunpowder for three reaons. 1. it does less damage than gunpowder weapons. Target shooting doesn't need an expensive backdrop behind the target, 2. It is quieter, this is usually not the main reason, but its an added bonus, you can shoot rabbits or rats quietly without being disruptive to neighbours etc. 3. It is less/un-regulated. meaning you don't need to go to a registered store just to grab some CO2 cartidges or it can even be filled at home However it doesn't change the fact that gunpowder weapons are still deliver much more kinetic energy therefore more damage (usually there are of course exceptions) **Gunpowder Weapons** AS you've already stated, things like the Russian APS already exist. could they be improved on? probably, but is there a need? not yet, but in your story yes there is. so improve the design a bit, increase the range, reduce the weight increase the damage. most people don't even know about the APS let alone know what it can effectively do. **Remote Controlled Weapons** Much more likely the way things are going to go in the future, however consider for a second what needs to be done to make this work effectively, and compare it to current technology: * Build a (most likely propeller) engine that can work at depth... Check * Provide a fuel tank/battery that can power that engine... Check * install a guidance system with basic control surfaces to allow maneuvering.. Check * Have a warhead capable of defeating a target... Check Well done, you've just built a torpedo All that would change is the size, shrinking it down to make it more man portable, and maybe increase the speed a little **However** I'm willing to bet that the more you think about the weapon and its practical use the closer you get to the thought process below... > > So in all cases, you need to carry Ammo, as well as propellant for the weapon. then most likely you'll need Breathable air and Power. Then you'll want some armour, some of it to protect you from enemy lasers and the water that is boiling straight out of your futuristic weapons and scolding your poor skin. the rest is to protect from the extreme pressure. Then you figure that your carrying a lot of weight why not propel yourself around with an engine of some sort, nothing too fancy, though but it will need its own power, or a bigger battery to share it with your future weapons. Then of course, you need your detection systems, whether it be active/passive Sonar or something else is up to you. Then maybe you decide that heating and lighting as well as the detection system would benefit from bringing a generator with you. Then you realize that your actually carrying a huge amount of weight so you need to propel yourself around with a bigger engine engine of some sort. Now you need a big ol fuel tank! even more weight, jeez its getting big now. Now your carry so much you expensive and delicate equipment, having someone with you to fix it if there was a problem, its a long way to the surface after all. and to be fair its now big enough to not be man portable anymore so you need someone to move you around and someone to fire the weapons. But hang on... what happens when i want to sleep??? well, i could put a bed in there for me, the pilot and the mechanic that'll work... Eating? yeah ok so a food store. and maybe a chef, that way we can stay down there for a really long time if needs be. We may as well carry a water maker and an oxygen maker then, save space on storing it, more room for Donuts!!! But what if someone shoots at us? maybe we should fit some countermeasures to confuse their remote control weapons and diffuse their lasers!!! You know that means we need a bigger engine again right? and a bigger fuel tank! Ok so while we sleep, we'll need some other people to control this strange thing and some more beds right? Why not save the big fuel tanks and just fit it why a reactor? tonnes of power... oh and some very well trained people to look after it > > > Well done my good sir, you've invented a submarine!!! [Answer] Things can't move very fast, or anyway it takes tremendous energy to move them real fast. And when you move very fast you leave a big arrow pointing at you. Munitions can't travel very fast very far. So munitions tend to be short range. Maybe the most effective munitions create a blast, so shear forces in the water tear things apart even from a near miss, but if you're too close the blast affects you too. (Unless it's a little tiny one.) And oceans are giant. So presumably to have a fight even make sense, your enemy has a specific target you want to take. They have defenses concentrated around it, and you send an attacking force to take it from them. You know in general where their defenses are -- they're defending it. You send your attacking drones near there. It's most cost-effective in terms of energy to send them on the ocean surface, but they can be spotted. It's fastest to send them by air but they can be spotted. Somehow you get them reasonably close and they try to sneak closer. The enemy detects them and strengthens its defenses against them, weakening the defenses in all other directions. When they are concentrated as much as you can get, you set off a small nuke to create a shock wave that destroys your whole fleet of decoys and their nearby defensive forces too. They can't just not concentrate their forces because your fleet might not be decoys. But if they are far enough away from the target they want to preserve, they can nuke you. If you don't care about capturing the target intact but just want to deny it to them, you can probably nuke it. [Answer] Not to be a downer or anything but lacking For each of foot in depth of salt water (fsw) you are adding 1 standard atmosphere (14 psi) of pressure. Go 1 kilometer under water and you are at 45,920 lbs / square inch of water weight pushing on every inch of surface area. Humpback whales can survive at incredible depths while holding their breath so maybe if our lungs eventually evolved to be more like theirs we could somehow cope with the compression / decompression but basically at those depths there is very little light and very little life. No matter what you stick a human in anything with oxygen is going to be in great peril just by being at depths below a few hundred meters. Everything below that depth will have to be with robots. You're going to need some kind of false-image sonar overlay just to percieve anything, which would give away your position -- or turn on lights which might also give away your position but probably less so than sonar because the light doesn't carry as far. Green light can still propagate (it is the last color to get filtered out, longer wavelength), so green lasers can still be used for positioning, targeting, liDar, maybe even energy weapons but the range will be very limited as water diffuses the light. ]
[Question] [ Imagine a busy port city with hundreds of ships in a medieval setting without gun power. The city is not heavily walled, and is located on a remote corner of the world, away from the jurisdiction and protection of the Empire. The city is a bit smaller than Amsterdam and it's northern, western and eastern sides are surrounded by a sea. A stretch of land to it's south connects it to the rest of the continent (think of the heel on the boot of Italy). The city has a small barracks and city guards with a small naval fleet to protect against pirates. Lets say the amount of guards and soldiers is 500 (is this number too low?) Is it believable, or possible, for an enemy army to successful conduct a sneak attack on land to the city without warning? What would the enemy force need to execute in order to interfere with the personnel of the city from relaying an impending attack? The land leading to this city is mostly green with some hills, but no mountains. This army does not have access to ships of their own, and travel on horseback. They total somewhere between 500-1000 men (is this too little or too many?). If relevant, the attacking army has magic which can manipulate minds, but the access to this kind of magic is limited. [Answer] I do think we need more details regarding the geography of the land around the port city, but I will do my best with generalized cases. **Genuine Sneak Attack** Here I assume the enemy army wants to attack and take the city quickly, breaching the walls/gates before the city guard can mobilize effectively. To do this they will likely need some aid from geography and maybe weather. Given enough cover, either by trees, hills, moon-less night, the army might be able to get close enough such that they can close in on the city quickly on horseback and overwhelm the guards. Maybe a fog rolls in at night time, or a whiteout caused by heavy snowfall in the winter, that might provide cover, even if there is no traditional cover. Perhaps even then, the army isn't able to get close enough to surprise the guards. In that case a better strategy would be to have a smaller strike force sneak in further ahead, able to seize the gates and/or distract the guards long enough for the main force to reach the city. Even better, the strike force has already infiltrated, disguised as refugees, travelers, or via secret abandoned/forgotten sewage tunnels. A plausible scenario would be, starting a fire or riot in one part of the city, that will distract the guards, then capturing a gatehouse. They then need to just hold on to the gatehouse long enough for the rest of the army to come riding in. **Cutting Off The City** Here I assume the enemy army wants to attack the city quickly enough such that the city cannot request reinforcements via land or, more importantly waterway. Here the enemy isn't too concerned with defeating the city forces, but rather more concerned with the city calling for aid and having reinforcements drive them off before they can breach the gates/starve out the port city. Without ships, it'd be tough to blockade the port city, but imagine the port city is on a peninsula extending into a protected bay. The enemy could then seize control of the bay's entrance/exit, thus preventing the port city from sending ships for aid, as well as send the main force to block the only land passage, effectively isolating the port city. They can then initiate a traditional siege of the city. [Answer] Think 'flashmob'. Build up a force over time. Claim a distant war is causing refugees in small groups to arrive in the town. Attack at once, first securing the means of communication. [Answer] # Use the pirates as diversion / decoy 1. **Wait until a pirate attack and attack simultaneously with the pirates.** This would split their forces and you can take advantage of their panic because they will not see your attack coming. This will also be a good pincer strategy. 2. **Make a deal with some pirates.** Pay them, to act as a diversion and attack with the same tactic explained earlier. 3. **BONUS**: Use your mind control magic to the pirates to force them to be a decoy. Preferably some lieutenants or the pirate captain himself because your magic is limited. Since you overpower the port city by numbers and their strength is with naval combat, you can feed their ego by giving them what they want: the advantage they ***think*** they have. Hopefully you have some kind of contact with the pirates because without them, the plan would fail. **EDIT:** The *persuasion* isn't necessarily conducted at sea. Preferably when the pirates dock to some remote town to take a break. The army will not need ships to do this. **TLDR: Use pirates, split their forces** [![enter image description here](https://i.stack.imgur.com/rL0cw.png)](https://i.stack.imgur.com/rL0cw.png) [Answer] I think we need to do some thinking about what it means to take the city "by surprise". In those days armies didn't have radio or telegraph, and they wouldn't be in a constant state of readiness. So you could be fighting with a few guards (who wouldn't be surprised) but if you prevent them from getting a message to HQ or you prevent HQ from alerting the garrison, you're still taking the *city* by surprise. In that sense a surprise attack is really a "head of the snake" attack -- you're trying to force the general or the prince to surrender before he can mobilize his defenders. Given that, the kind of a ruse that you might see in a silly movie could actually work. Think of how Westley, Inigo, and Fezzik got into Prince Humperdink's castle in *The Princess Bride*, or how Mel Gibson's William Wallace in *Braveheart* tricks the English garrison into opening their gates (by wearing uniforms taken from a captured patrol). Realize that in the days before gunpowder, each fight is man-to-man. A small group of infiltrators can fight a small group of guards, take the gate, and let their comrades in. Arrive at a time when you're not expected, for example, in the winter. Before the American Revolution, armies generally didn't fight in winter but sheltered in place. Washington was able to win the vital battle of Trenton by attacking at dawn on December 26th, when the enemy simply had no expectation of possible attack and hence were not in a state of preparedness. (This was of course a desperate risk by Washington, whose troops might not have survived if they had to retreat, so that's the trade-off.) Once within the city walls, your army's task is to get to the enemy headquarters and capture the prince or the general, forcing him to surrender. Now, if your attacking force is really small, eventually the lower-ranking commanders of the garrison will realize that you're bluffing and may re-take the city. So you have to act fast to consolidate your win, perhaps by demanding they disarm, keeping them separated, turning them to your side, getting the church to officially recognize your right to rule, or bringing in reinforcements. ]
[Question] [ While similar to other questions they mostly focused on what impacts required in the past to keep airships as a popular air transport method today, this question is about how to make airships the dominant method air transport method ASAP. What I want to know is what changes can a single man make to make air transport dominated by airships. It can be political (such as taxing other forms), it can be engineering related, the only thing that are a must is as follows: * There is no worldwide "blimp cabal" (unless you figure out a realistic way for a single man to start one) pushing for this change, the man pushing for it can pay\bribe others if he's rich enough but he can't be richer then the richest man currently alive, if he's a politician he can be the president of a country (any country, pick one) but can't be of two (or more), he can be anybody you want but while he's powers and abilities can be great but they have to be realistic. * No magic, this man lives in the modern real world. * The man is over 18 & wants to live to see his dream come true so answers that play too long of a game won't work. * Just to make it clear the man can in fact be a woman. [Answer] The answer is simple, a very rich man makes blimps very cheap to use. It will definitely drain his pocketbooks quickly, but so long as the prices are very low people will choose airships to travel on. Lots of small companies will likely use them for shipping and passengers who wish to travel abroad but couldn't afford it before will take it up quickly. Depending on how spacious the blimps are and how fast, people may choose them over busses for a lot of travel, and possibly over trains if not for novelty then for savings. Anyways, its an uphill battle and you can't make it the best form of transportation, just popular enough to be in use. [Answer] First, I think your best bet is to focus not on traditional blimps and dirigibles, but on modern hybrids like the [Skytug](https://en.wikipedia.org/wiki/Lockheed_Martin_P-791) and the [Airlander](https://en.wikipedia.org/wiki/Hybrid_Air_Vehicles_HAV_304/Airlander_10). Hybrid aircraft are vehicles that use LTA (lighter-than-air) technologies for some of its lift, while also having HTA technologies like wings (hybrids with wings are often called "dynastats") or rotors ("rotastats"). Even without understanding the detailed technology, it should be easy to intuitively grasp why hybrids are promising. In the same way that hybrid gas-electric cars can give you most of the benefits of an electric car without most of the disadvantages, hybrid aerostatic-aerodynamic aircraft can give you most of the benefits of an airship without most of the disadvantages. To some extent, this is still technology in the experimental phase. The US Army's LEMV project (which triggered much of the initial funding) was canceled without putting anything into actual operation, and the civilian startups that spun off from the increased interest are still not exactly mass-producing commercial products. --- The specific potential advantages of hybrids include: * Size. The Airlander is by far the largest aircraft around. * Transport mass. Some (unproven) rotastat designs can carry an order of magnitude more than helicopter "aircranes". * Lower fuel consumption. * Longer flight range. * Shorter runways (without the massive fuel costs of VTOL). * Possible cheaper airports (a side effect of most of the above). * Lower operating costs. * Not particularly interesting to terrorists. (It's hard to blow up a building with a giant helium balloon that's only carrying a tiny fraction of the jet fuel of a similar-scale jumbo jet.) However, a hybrid that can travel as fast as a typical long-range passenger plane at reasonable costs is probably not plausible with current technologies. And obviously, replacing something like a fighter jet is even more implausible. So, the way to make hybrid airships "the dominant method of air transport" is to change what air transport is useful for. --- One option is a fossil fuel crunch, or a worldwide depression. If it costs £500 instead of £50 for a Ryan Air flight from London to Barcelona, and most people can no longer afford to spend that much on a vacation, then a £50 alternative that's much slower than a jet but still faster than a train or driving looks pretty attractive. --- But a more interesting option is to expand air transport instead of shrinking it. Make hybrid aircraft the dominant form of air transport without even putting a dent in aerodynamic transport, by eclipsing it. Find things that are done mostly by surface, or not done at all today, that could instead be done by airship. * Cruise airships. This has always been the thing airship enthusiasts focus on, and it's obviously never been nearly enough on its own—but as one component of an expansion of airship travel it certainly can't hurt. * Rotacarriers that can launch fighters, bombers, and cruise missiles from the air, without needing an alien energy source like the Helicarriers from the Marvel movies. * International deliveries almost as cheap as 4-to-6-week shipping but only taking a few days. (And imagine the large airships serving a fleet of small local airships which directly launch drones for the last mile.) * Airship supertankers. They're never going to replace seagoing tankers for some things, like oil, but shipping perishable produce? * Air ferries. Drive your car onto the airship at Rostock, arrive in Copenhagen before the sea ferry has even made it to Gedser. * Aircranes. Today they're mostly only useful for things like rapid military engineering, but hybrid aircranes could replace fixed cranes for everything but massive-scale long-term uses like dockyards. * Local transport between places too small and remote to be worth fully servicing by jets. A 20-minute flight can't beat driving if it requires a layover in a hub city, but a 90-minute airship flight can. * Commuter transport. Go to the airship airport in eastern CT, board the same way you board a train, land in Manhattan… who'd bother taking a train? * Transporting vehicles and resources for remote expeditions and military buildups. * Strategic command/recon/intelligence. This is what the US Army's LEMV project was about. Imagine an AEW&C aircraft that could do everything the E-3 AWACS does at a fraction of the cost, with much simpler and cheaper in-air refueling so it never has to land, with the ability to launch a fleet of recon drones, and without the weight limitations of a 707 body. You'd still want something jet-based like the E-8 Joint STARS for rapid deployment, but for everything else, it would be hard to beat a command airship, if it all works out.1 I don't know which of these is most promising in the near term, but an Elon Musk type (but with even more money) could do the research to answer that question, focus on one or two at a time, and conceivably pull it off within a generation. (Especially if he doesn't fight to maintain dominance in each new field he opens, but instead welcomes the competition, and meanwhile uses the money from his market lead to jump into the next market on his checklist. It would only take one or two successes like that before people are ready to throw money at him for whatever he tries next.) --- 1. Obviously, the US Army disagrees. But, even ignoring the argument that LEMV was probably ahead of its time, if you look at where they put their funding after canceling LEMV, it mostly went to [JLENS](https://en.wikipedia.org/wiki/JLENS). I don't think a blimp enthusiast would be too disappointed by having to share a bit of the air expansion with helium-lift vehicles that are only not considered airships because they stay tethered and never land. [Answer] **Fossil fuels are bad for the environment.** This man should convince the world that all planes burn fossil fuels, and if we want to save the world from global warming, we need to stop this practice. By contrast, dirigibles will fly on safe helium and electric motors. Eventually, all governments will enact laws that would make traditional planes very expensive to operate. Some countries may ban them altogether. New era of electric cars, trains and dirigibles will dawn on us! [Answer] **Terrorism.** You're never going to out-compete planes with blimps or dirigibles on their merits (not without fantasy-tech, anyway,) so your only real option is to artificially and astronomically increase the risks/costs associated with the competition. If the man is able to sabotage or otherwise destroy enough planes (preferably in the air, which increases risk for users, but on the ground can work too,) society will stop using them as the risks begin to outweigh the benefit of fast travel. The actual number may not need to be huge if he can maintain his assault without getting caught/countered. Even a single high profile airliner accident can put a (short term) dent into ridership numbers; imagine if an airliner, somewhere, went down every few days. Passenger flights will quickly grind to a halt. Freight will take a bit longer, but as the overall number of flights go down the risk to any given remaining flight will rise, so the chilling effect will snowball. Of course, there's the question of how to pull something like that off, even if you have a huge amount of resources at your disposal. Traditional tools of terrorism like bombs aren't going to be sufficient. You would probably need to infiltrate all of the major manufacturers. If you're rich enough, buying a controlling stake in them would be a good start. Boeing's market cap currently is ~200B, and Airbus' ~100B, so that's not completely out of the question. All of that would of course be an extremely long shot, and your risk of getting caught before you succeed in your mission is overwhelming, but that's going to be your most viable path. This of course assumes that the man is willing to be a mass murderer (or at least cause incredible economic damage) to see his life's quest realized. [Answer] You seem to want or need to have a person single-handedly responsible for the shift from heavier-than-air flight to lighter-than-air flight. I'd like to suggest an alternative approach which may give you the result you require. Back in the 1970s there was a some fairly serious talk in some circles about a possible resurgence in the popularity of blimps and dirigibles for long-distance travel. The reason? The Energy Crisis which began in October of 1973. Currently we are undergoing a climate crisis based off the use of fossil fuels, and oil-based energy continues to become more expensive as we continue to burn through irreplaceable reserves. Additionally, consider that while airborne transportation is very popular with over 100,000 flights worldwide per day, it seems to be increasingly difficult to turn a consistent profit from year to year in that industry. Wikipedia lists 83 airlines, since 1979, which have gone out of business, re-organized as another business, or have merged with a larger airline. You'd have to work out the timeline, but I would suggest a future where it is simply too expensive for most commercial endeavors to employ heavier-than-air flight in their daily operations. One man has seen the writing on the wall and has positioned his considerable wealth into the re-development of dirigible and blimp technology. During the crash of oil reserves his gamble pays off and he's now the leader of some dirigible monopoly. Dirigibles would now occupy the place of the ocean-going liners of the late 19th and early 20th century as the primary mode of international transport. A 1930s dirigible crossing of the Atlantic took from 3 to 4.5 days, depending on weather and routing and such; I would suggest that with modern technology and knowledge of atmospherics one could probably guarantee a crossing in either direction in 2-3 days. An envelope calculation figures that it would take about 1.16x10^12 cubic feet of helium to carry the same amount of cargo as a supermax vessel, so you may want to consider a similar, parallel, ocean-going **sail** industry! It currently takes a cargo vessel 9 or 10 days to cross the Atlantic -- sometimes as long as 20 days, depending on the actual destination. My own limited experience with ocean-going sailing makes me believe that a modern cargo vessel with the best sail technology would take a good month to cross the Atlantic. So: maybe the majority of cargo is moved around via ocean-going sailing vessels, but you'd still have some class of super-dirigible for carrying cargo more quickly. Helium without an oil-based economy is an interesting problem. We don't have a lot of helium in the atmosphere because it's so light; it floats to the top of the atmosphere and is blown off by the solar wind. My understanding is that we get most of our helium from the oil industry. So if you want your dirigibles to be elevated by helium, you're going to have to find a source. I would suggest a world which uses fusion energy. It's a source of energy which would be only economically feasible for city-scale power production, but which produces helium as a "waste" product. Now you have a cheap source of helium. But, fusion power would be too expensive, not to mention too bulky, to power even a very large cargo vessel, much less an aircraft. Now, while hydrogen has proven historically to be a bad choice as the lifting gas for dirigibles, I would suggest that is only true using 1930s technology. Using modern technology and materials the use of hydrogen as a lifting gas would arguably be much safer, with the added benefit that you can use it as a fuel for propelling the dirigible. So, if it's a story you're writing, or an RPG milieu, you may want to use hydrogen as the lifting gas to introduce some kind of balance or limiting feature in your world, especially if you really don't want to use fusion technology. And the use of dirigibles would not preclude the use of fossil fuels in other areas. The military, of course, would continue to use fossil fuels in nearly all their aircraft. Private and government aircraft would probably use jets powered by liquefied hydrogen. Those are my thoughts on this interesting question. Hope that helps. [Answer] **Focus on Underdeveloped/Remote locations** The best way to beat planes is by ensuring you have a monopoly/cabal by the time they become attractive. A lot of places in Africa for example could be connected with airplanes, but there's simply no infrastructure to land them and even if they got an airfield there's still the question if there's a road from the airfield leading to wherever it is the cargo or passengers must be. An airplane requires an entire airfield (provided you want real cargo planes and not small WW2-era soviet proppeler planes and such), whilst an airship merely requires a small clearing. Airships can transport more cargo in one haul. If you have a plant for lifting gas then you can save a lot on the fuel bill as well. Basically ensure you got a dominion on air traffic by the time the country becomes developed enough to start planting down sufficient airfields and roads to mess up your business plan. I can only see this taking off in underdeveloped countries, because cities in Europe for example are too close to each other to make trains unattractive for short and mid-ranged travel and aircraft handle the long range stuff and in North America you got plenty of airfields, railways and well-build roads. Not to mention in these places there are 'cabals' active protecting the airplane industry or the trucking industry or the train industry,... It also helps that in a lot of African countries there are dictators. If you can convince and befriend those people then you're good. Sure you have to worry about being backstabbed, but if all goes well...you're probably in a better position than say in the USA or Europe. [Answer] A single man can do the following: * Discover an easy way to produce helium * Develop an optimal shape to minimize effect of cross-wind, or harpoon anchors that keep landing blimp stead during takeoff and landing (thanks to user535733) * Prevent Hindenburg disaster (I hear it might have been sabotage). Instead, stage several similarly spectacular airplanes crashes, e.g. killing the beloved royal family in front of a crowd gathered to welcome them. Or crash a school trip. Or convince military rival to use kamikaze. Other world changes that would help if you are willing to use them: * Very rare fossil fuels, or not enough quality metals to make powerful but compact combustion engines. Airship can be powered by a steam engine (and use heat to keep zeppelin in the air) * Humans vulnerable to even moderate acceleration (airplane pilots pass out) * Less wind, as user535733 has said. Or rather less wind at ground level, and more turbulence up high. Larger vessels are less affected by turbulence. [Answer] Because aerodynes (fixed wing aircraft and helicopters) so decisively outclass LTA in virtually every aspect of air travel, what you are asking for is virtually impossible. Unless you change the timeline to have [Leonardo da Vinci](https://infogalactic.com/info/Leonardo_da_Vinci) be the inventor of dirigible airships. Leonardo was a polymath, and keenly interested in the science of flight. Like most people of his day, he considered the only true natural model to be bird flight, and spent a great deal of time studying bird flight and attempting to design [Ornithopters](https://infogalactic.com/info/Ornithopter) to allow humans to experience flight as well. Although his designs included subtle details like ways to flex individual portions of the wings to control the flight, much like a bird does, he never overcame the fundamental limit of human muscle power, which makes ornithopter flight extremely difficult (even with modern materials, gearing and other innovations which would be far beyond anything Leonardo had access to). [![enter image description here](https://i.stack.imgur.com/QzJbU.gif)](https://i.stack.imgur.com/QzJbU.gif) *Leonardo's flying machine* However, Leonardo was a polymath, and among other amazing things, designed a submarine for [Ludovico Sforza](https://infogalactic.com/info/Ludovico_Sforza), indicating he was also aware of the principle of displacement, and how to manipulate it in a fluid medium. [![enter image description here](https://i.stack.imgur.com/ePJ0d.jpg)](https://i.stack.imgur.com/ePJ0d.jpg) *Model of Leonardo's submarine. The white "bags" control the buoyancy* The last invention to consider is Leonardo's "Roasting Jack", a device which used a form of turbine to capture the energy of hot air rising from a cooking fire to turn a spit. [![enter image description here](https://i.stack.imgur.com/nC0Ax.jpg)](https://i.stack.imgur.com/nC0Ax.jpg) *Leonardo's roasting jack* Now we rearrange Leonardo's thinking a bit. He is keenly interested in flight, but aware not amount of human effort will ever cause his flying machines to work. He knows that increasing or decreasing the bouancy can cause an object to rise or sink in a fluid medium, and he knows hot air rises. "What if..?" he wonders "The bags in the Submarine were filled with hot air"? Some weeks of experimentation in his workshop soon allows him to create hot air balloons in the late 1400's, and his patron, Ludovico Sforza, the Duke of Milan, is very quick to see the advantages of air observation. Soon, with the amount of support he is getting, Leonardo begins adding bits and pieces of his other inventions to the design in order to have powered flight. A clockwork device from his car can power Archimedean screws, for example. [![enter image description here](https://i.stack.imgur.com/sR3hM.jpg)](https://i.stack.imgur.com/sR3hM.jpg) *Leonardo's car. The clockwork "engine" can provide power for flight* While Leonardo's airships would be very rickety and limited, humans would have powered flight starting in the early 1500's. With 500 years of development, airships would be refined to a very high degree, and since most of them would likely be thermal airships (i.e. have their lifting power from heated air), they would be much safer than the hydrogen balloons and airships of our timeline. In this timeline, people who advocate for heavier than air flight modeled after birds would be dismissed as cranks. [![enter image description here](https://i.stack.imgur.com/KfxU8.jpg)](https://i.stack.imgur.com/KfxU8.jpg) *Skyyacht thermal airship prototype* [Answer] Instead of making it the dominant long-range transport, make it the dominant short to mid-range transport. As you can read here: <https://tvtropes.org/UsefulNotes/Airships> Airships of the modern age are extremely resilient and are in some cases even better resistant against tough weather than modern aircraft, with most weather related accidents happening because the pilot of the airship overestimated the Airships capabilities. Through the use of gasses these Airships are cheaper to fly than conventional aircraft and helicopters. With loads of up to 250 tons they can transport cargo or personnel and heavily reduce traffic. The big problem is demand and production: if no one buys them or produces them the price remains high. So the rich man does what any person would do: he starts research, production and advertisments. With a small cargo company for starters (as example) he could show successes circumventing tough traffic areas like cities and providing safe, fast and reliable transport (you need it somewhere at a specific time? This thing aint bothered by trafic jams or the hour of the day!). From there as more Airships can be produced, demand rises and others try to mimic the success the airship business can take off. An alternative/additiin might be to transport people between cities like trains, only you dont need to build and maintain rails and can increase/decrease airship traffic based on demand more easily than trains can. Actually something very much like this is happening right now where I live: someone "invented" an electric, cheap and ultra-light mini-truck. Electric trucks used to be as anathema as Airships. A business was made that allowed you to order a very basic set of foods and drinks at a low price and have it delivered for free. This is possible as the owner doesnt have to pay for stores, the trucks drive dirt-cheap on electricity and the owner only needs a warehouse. This has been so successful that when my wife applied for it she came on a waitinglist of more than 6000 people, and the only way that list went down was by buying enough mini-trucks to supply it, and that list has been exponentially decreasing all because of the re-invention of existing technology in a way nobody thought would be useful. So by that model using something similar for Airships should be possible. Edit, part of the link: > > The newest, fastest(90-140 mph) class of airship. Hybrid airships are not hybridizations of different categories of airship. Rather, they are hybrids between lighter-than-air(LTA) airships and heavier-than-air(HTA) vehicles such as airplanes, tiltrotors and hovercraft, and often all of the above in that they combine the two main methods of generating lift. In a pure LTA aircraft all lift is generated due to buoyancy of its gasbag, and in a pure HTA aircraft all lift is generated from aerodynamic forces — usually the pressure difference on the both sides of a moving wing, either fixed as in a plane, or rotating, as in a helicopter. Hybrid airships derive their lift from both sources, and many proposed designs can actually vary the ratio between them. They are an extremely recent category of airship, and are preferred by many over LTA airships because of their larger cargo payloads. A hybrid the size of a midsized blimp can carry 20 tons. Hybrids the size of the Zeppelins of the early 20th century can carry 250-500 tons to the Zeppelins' 50 or so. But even more important than the larger payload is their ability to land without expensive, specialized ground assistance, and their greatly increased redundancy, safety, and resistance to bad weather. Hybrid airships can be any class of airship. Notable hybrids include the Lockheed-Martin Skytug, the Solar Ships, the Aeroscraft, and the U.S. Army's LEMV. > > > [Answer] **Solve the low-altitude problem** Lots of the original problems with aerostatic vehicles have *already* been solved in the last 80 years: We have stronger and lighter structural materials, fireproof-and-puncture-resistant gasbags, lighter and better energy sources and motors, vastly improved understanding of the atmosphere, excellent long-range navigation, fantastic weather data collection and modeling capability, and trivial high-data-rate ground-to-air transmission today. However, the big problem remaining today is the one that ended most civil aerostat programs in the 1920s and 1930s: An errant wind during landing or takeoff can smash your expensive vessel into the ground, a building, nearby trees, bodies of water, or snap the line and kite it away. The greatest threat to airships is proximity to the ground. That's the risk the prevents a real airship rennaissance. S/He must find a way to significantly reduce that risk. [Answer] ## Prove Global Warming / Get Jet Fuel Taxed The main advantage Lighter Than Air vehicles have is fuel efficiency. So that is the thing that needs to become the dominant factor in aviation. In a variant of Alexander's answer, your protagonist must create an AI or climate model that predicts everything happening to global weather changes and longer term changes. Preferably, it accurately predicts the number and strength of hurricanes as well as floods and droughts. Rather than engaging in a mission impossible to convince the governments of the world that actions need to be taken based on this, the model should be marketed to insurance companies across the world. They will love the improved risk modeling, freak out at the longer term risks and raise their premiums sky-high. With the general population suddenly unable to insure their houses and businesses, they will demand action from the government. Your protagonist, with the backing of Big Insurance, can then show how climate change can be reduced by immediately scaling back fossil fuel use by CO2 taxes or even forbidding further extraction of coal, oil and gas. This won't happen easily or all at once, but the proven track record of weather disaster predictions plus somewhat accurate cost/benefit projections of action vs inaction will get governments moving. With jet fuel going from tax-free/subsidized to heavily taxed, airplane travel will become unaffordable for most. That creates the perfect conditions for the Return of the (solar-powered) Blimp. ]
[Question] [ So the story goes that in 212 BC Archimedes used bronze mirrors to incinerate Roman ships as they approached the harbor at Syracuse. This along with other ingenious inventions aided in keeping the Romans at bay until they were able to scale the walls of the city while it was distracted during their annual festival to the goddess Artemis. Wikipedia: [Siege of Syracuse](https://en.wikipedia.org/wiki/Siege_of_Syracuse_(214%E2%80%93212_BC)) Subsequent attempts to prove or disprove the concept that Archimedes had indeed created and employed a “heat ray” using bronze mirrors have had mixed results. Some tests were concluded as positive, see e.g. [Mythbusters were scooped — by 130 years! (Archimedes death ray)](https://skullsinthestars.com/2010/02/07/mythbusters-were-scooped-by-130-years-archimedes-death-ray/) by Dr. Ioannis Sakkas, using sailors standing on the shore holding mirrors. Others have concluded that while it’s possible Archimedes’ mirrors could ignite a ship it would be only under ideal conditions and that since the harbor of Syracuse faces East it would only work in the morning. This conclusion seems to indicate that it was unlikely that this was what was employed in Syracuse’s defense. [2.009 Archimedes Death Ray: Testing with MythBusters](http://web.mit.edu/2.009/www//experiments/deathray/10_Mythbusters.html) That said, my question is at what point in human history (era or approximate years) would it be possible to create and deploy a “death ray” capable of instantly lighting aflame and sinking a wooden ship anchored at harbor a “bow shot” away? Additionally it would need to be capable of being employed against multiple ships either simultaneously or in rapid succession as would be required to keep such a fleet at bay. The death ray would ideally make use of solar power as that is what is typically described in Archimedes use of the “death ray”. [Answer] **It could have worked** at any time that was able to produce bigger sheets of flat reflecting metal, or glasses with reflective metal coating. It's all about the heat flux: Incident power per surface area. This was very relevant in firebombing, and nuclear bombing, so the military made some tests (Lawson, "Fire and the Atomic Bomb"): 55kW/m² will ignite fibreboard in 5 seconds **25kW/m² will ignite wood "after prolonged exposure"** The sun will easily provide **1kW/m²**, so ideally you would only need 25 pieces of 1.xm² mirrors (.x to account for the angle of incident sun to target vector and the non-perfect reflectivity, probably something like 1.5) and some time. The 1m² rays do not need to overlap completely, a smaller area where they all overlap would be enough. the suns beams are essentially parallel, so you will not have to account for natural beam divergence - big BUT coming up, though: BUT: This also explains the neccessity of "flat" mirrors: The rougher or more bumpy they are, the less of the original ray will actually strike the target - you will need to have as flat a mirror as possible - glass cast on liquid lead or tin will be very flat indeed, but i don't know if that method is applicable in pre-industrial times. **A pre-industrial method** might involve small pieces of metal made extremely flat, that are affixed onto a shield and individually positioned by an artisan (occlude all others, have the shield in a fixed position and then, at noon, glue the piece in place and light up a specific target a bowshot away while the glue settles. Repeat for all little pieces, then you have a shield thats very accurate. now repeat for 50 other shields - typical pre-industrial drudgery by specialists. If the shield-fixator was cleverly built, the reflecting angle of the shield (i mean the angle between the affixed points and the virtual surface of the mirror) would be known, and you could construct **a mechanical device that angled all the shields** for a specific sun inclination and target-vector (The neccessary individual angles are all a function of shield position (on device), sun position (relative to device) and target position (relative to device), and the mathematical function would be (easily?) modellable by levers). You could even have a (probably multi-person operated, because mechanical) joystick and target/sun sights (like on a sextant) to aim. Might be even better than having humans hold the shields individually. **If you are not into big mechanisms**, consider this: have a target buoy bobbing around in the targeted area. Have a foundation for every mirror-shield, have an ironsight (= annulus near the eye, many beads strung into field of view) one person is at the sights. have a sun locator (a stick in the ground, with a design drawn around it so the shadow can be located) with person watching it. Now target the buoy by lighting it up with one shield at a specific sun location&target (=buoy) location. the shield-mover now can sketch the shield position for that sun location and target location. Next shield. Next. As the target bobs around in the harbor, and the sun walks over the sky, the shield-movers will sketch a lot of sun/target combinations. These will correlate, thus giving them the means to guess at configurations for un-trained sun/target combinations. On the day of battle, have the sun-guy and the target-guy call out their readings, everyone else just moves their shields to the pre-determined positions.If we determine a "bowshot" distance (as per olden sources) to be 200m, 1 degree of error will displace your ray by about 2 metres. With 1m-diameter rays we should stay below 0.5m error, so 0.25 degrees would be the maximal acceptable error. Is that achievable? For a circle 2m in diameter, 1° of circumference is about 2cm, so 0.5cm error for the tip of a stick attached to the shields. achievable, i'd say. **A pre-industrial source for ultra-flat surfaces** might be crystals, but i doubt you'd get enough crystal-faces for the area needed. But even the ancient Egyptians had hand mirrors, and those definitely need to be flat, so i guess they had some experts that could make them that way. If you know of a method to get any hard substance really flat, you can always cover that in gold leaf (very ancient material too) and polish it, so pouring ceramics or something might work also, you'd just need one super-flat mould. [Answer] While this is theoretically possible, there are a lot of practical issues with the story, and the number of attempts to replicate this have generally been negative. Perhaps the largest problem is practically focusing the beam using multiple mirrors. While you could conceivably swing your mirror or bronze shield to reflect a spot onto a target, once a multitude of people are doing this, it becomes difficult to adjust "your" beam. The entire target may be brilliantly illuminated, but getting the proper focus on one spot long enough to reach ignition temperature for wood ([between 190-260 degrees C](http://www.tcforensic.com.au/docs/article10.html#2.1.1)) becomes extremely difficult. A modern device with can precisely hold each individual mirror in focus is possible, and [solar furnaces](https://infogalactic.com/info/Solar_furnace) have achieved temperatures of thousands of degrees. I might suggest Archimedes cleverly used the blinding spotlight effect for more nefarious purposes: the ships crews could not see the defenders of Syracuse run up with small torsion catapults and fire flaming darts at the ships (if they were on the pier without cover, the Roman ships would have cleared the area using "[Scorpions](https://infogalactic.com/info/Scorpio_(weapon))" mounted on the ships). The Romans would have been blinded by light then had fires starting on the ships, ships farther out might not be able to notice the darts but would see an association between the ships being suddenly lit up then catching fire..... [Answer] The principle was understood but as Thucydides mentions there are targetting and focus problems once you build up high enough numbers of mirrors to have a significant effect. So let's work backwards from more modern technology to help with that problem. Consider a device, it looks a bit like a [sextant](https://en.wikipedia.org/wiki/Sextant). From one side you see the sun, on the other side your target. It's mounted on top of your mirror and moves with it. Your job as a solider of the 21st mirror battalion is to keep the image of the sun aligned with your target point on the image of the ship. You've trained for the past 6 months to be able to do this. *This requires relatively advanced optics and engineering, the sextant didn't come along until the 1700s, but the principle is sound.* For more basic technology consider two linked markers, when one shows/blocks the sun and the other shows/blocks the boat, your aim is correct (or at least good enough for government work). Consider instead a mirror with holes in it, held a reasonable distant in front of you, eyes aligned to the centre, the holes are marked in 4 quarters, the sun is visible through one hole, the ship must be visible through the diagonally opposite hole for correct aim. The idea here is to find some way for the individual soldier to accurately aim the mirror without having to identify their own personal bright spot on the ship, as soon as you've solved that problem the death ray becomes viable regardless of technological level. [Answer] Some solutions: Use warped convex glass lens instead--ever fried a leaf with a magnifiying glass? If you used a lens large enough, it could set fire to something. As for timing: Quite early--types of natural glass already exist, and some types can be formed as a byproduct of metalworking. All you need, really, is (purepurepure) sand (silica) and maybe lime. You could have mini ones for soldiers to carry around all the time, and then focus on a point from several places. Try a Fresnel lens: curved ridges on the lens that help focus the sunlight more. Use silver or aluminum--both are highly reflective metals. I imagine once you have a furnace big enough, you can make revolving plates to reflect/concentrate sunlight. As for night technology: you would need to wait for electricity to come about, in which case you would use something like heat-generators or lasers. In any of these examples, you would need multiple lenses on swiveling turrets to take care of a ship. So perhaps station several groups on walls or coasts? I'll update this as I come up with more ideas. [Answer] With regard to the problem of aiming the output of individual flat mirrors at a common distant target: A common element in a survival package is a *two-sided* flat metal mirror with a small hole in it. The instructions for reflecting sun light to a target are : 1. Hold the mirror so that you are can see the intended target through the hole; 2. The sun shining through the hole will put a spot of light on your face/neck/chest. Find that spot of light by looking at the mirrored back-side of the metal mirror; 3. *Without changing Step #1*, tilt the mirror around until the spot of light on your face/neck/chest "disappears" into the hole in the mirror You are now reflecting sunlight towards the target. Note: In a multiple person attack scenario, you would not need to see "your" spot of light on the target. nor pay any attention to what your co-attackers are doing The geometry and physics needed to prove this technique requires only simple Euclidean concepts (angles in intersecting straight lines), and basic physics (angle of incidence equals angle of reflection). An individual attack mirror would need only a small mirror on the back-side, mounted parallel to the front-side mirror. This technique has been addressed, with diagrams in this SE answer: <https://outdoors.stackexchange.com/questions/15998/how-do-you-aim-a-signal-mirror> [Answer] Now. [![enter image description here](https://i.stack.imgur.com/lGsLx.jpg)](https://i.stack.imgur.com/lGsLx.jpg) From <https://inhabitat.com/energy-breakthrough-storing-solar-power-with-salt/> Mirrored surfaces in computer-controlled mounts track the sun, keeping it aimed on the target. It's not that much of a stretch to make the mirrors be mylar drums who's "concaveness" can be controlled by vacuum pumps, and aimed at a ship at sea, not a central tower. It would require lots of servo controls and constant tweaking of all the mirrors as the ship bobs up and down, back and forth, or even sails away, but computers are definitely capable. Not that it would be practical. A flight of Exocet missiles would be a *lot* cheaper... [Answer] ## I think 212 B.C. Modern attempts to replicate the 'death ray' use what we think the average Greek had access to. *Archimedes wasn't average.* The mind that can conjure up an Archimedes spiral, the principle of buoyancy, etc, etc, could jolly well have had some better ideas about mirrors than polishing enormously heavy sheets of bronze. Furthermore, we know that occasionally the ancient world produced things that were seemingly centuries more advanced without them being replicated. Look at the Antikythera mechanism and tell me that it's not possible that Archimedes plus a war economy couldn't have done something that wasn't rivalled for centuries. ]
[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 4 years ago. [Improve this question](/posts/109566/edit) My story is set in The Walking Dead universe. Quick explanation for those who don't know what that is: Comic and TV show about zombies and more about how the survivors deal with the apocalypse than the zombies themselves. The idea of a zombie doesn't exist in TWD'S universe, which makes observing the people of this world deal with them that more interesting, but the zombies very quickly become a background environmental hazard as survivors quickly realize humans are the real threat. My story is set in New York, following an adolescent character that was a tourist before the apocalypse happened and is now stuck in this foreign land forever. He becomes the leader of a very prominent community residing in Manhattan. Because of New York's density, everybody fled out of the city when the outbreak began as it was filled with zombies, but with time, the zombies moved out, either from being attracted to noise outside the city or just shambling around. Because nobody dared to enter the city, it was like heaven to any survivor, a ghost town of a city filled with almost completely unlooted stores. Because Manhattan was the closest and most familiar borough, the adolescent and his group resided there and that's where the group grew up to become an empire, regarding Manhattan as their "turf" and mainly residing in central park, but also in a couple of other outposts in Manhattan. With time, the group comes across two more large groups, one in Bronx and one in Queens. They aren't as big as his group, but they are big enough to do major damage, and would be even bigger if they decided to team up against him, so he builds an alliance between the three group and they all agreed to trade, but there is still some uneasiness between them all, as all three keep a close eye on each other in case one decides to plot against the other for more land and power. Think of it like the relationship with USA vs Russia vs China. That's kind of the "gist" of the story. Now about the character. He very quickly adapts to this new and cruel world, and his ways early on are deemed "inhumane", "monstrous" and even "barbaric" by the people still clinging into their humanity, but with his skills and confidence, people have no chance but to follow him as he seems to know the most out of the group. He's around 17-19 years old, and is by no means a goodie two shoes or a perfect hero, he's actually pretty ruthless, manipulative, cunning, insecure, opportunistic and is willing to do whatever it takes to increase his power whether it's wiping out an entire group and taking their stuff or giving them no choice but to join him, killing a group member who he feels might plan a revolt against him, publicly torture and/or execute people and decorate the surrounding areas with their bodies for the people to see and make any other person/random traveler/surrounding groups fear him. With all of those scary qualities, he has some good ones and morals to some extent. He doesn't like hurting children, the elderly, and parents as they remind him of his family that he couldn't see anymore (but he would still punish a parent(s) or an elderly person if they commit something against the rules, but he would either think long and hard about it or/and lessen the severity of the punishment based on the offense) and because he doesn't have any friends and family like back home, he truly tries his best to build bonds with his comrades and people in his community. They all drink together, have fun together, tease each other, play games and such. Even though he likes power, he hates being separated from his people and being regarded as a superior, and wants to be WITH the people, as it reminds him of being home, because they are the closest thing to family he has. So he's ruthless, manipulative, opportunistic, but fiercely loyal, friendly, and usually polite even to his enemies (or sketchy allies, like the Queens and Bronx groups) Now here's the problem, how do I make it believable that people still followed him roughly a year after the apocalypse? since a year has past, surely people have adapted to this world and the weak ones were weeded out early on, how do i make it believable that hardened adults would listen to this hardened, but also adolescent boy? How could they follow him and take him seriously? (Which is another issue I touch on in this story, he's too mature to befriend some of the adolescents of the group, but also feels some of the adults don't take him as seriously as he thinks they should, mostly the ones he initially meets/from surrounding groups.) Hope my great wall of text sorta made sense! (This is my very first post; I apologize if it looks ugly.) [Answer] **Your teenaged tourist in NY was not originally American.** [![isis child soldier](https://i.stack.imgur.com/jegG8.jpg)](https://i.stack.imgur.com/jegG8.jpg) <http://www.breitbart.com/national-security/2017/06/15/islamic-state-philippines-recruits-child-soldiers-promises-islamic-education-poor/> He is a refugee, having spent the first part of his life as a child soldier. He has experienced terrible things in his short life. He has not been in the US long and America seemed almost too peaceful. It turns out that this peace was not to last. His old habits and hardness served him in good stead. If this is prose fiction, do not lay out this backstory all at once - hint that he might have some PTSD, that some things in the US are still new to him. He can have a flashback. He can make use of the things he learned. The New Yorkers who form his group include several immigrants among them, but none with his experience. And none of them are going to catch up with him, no matter how hard life after the zombie apocalypse is. Your leader can feel like an outsider because he is a teenager, because he is a foreigner, because his skin color is different from that of the group, because he remains an observant Muslim. But he learned early that leaders lead and show no weakness to those below them. Sometimes he can leverage that difference into effective leadership. Ultimately the reason they stay with him is the same reason people stay with any leader. He is good at it and he gets the job done. [Answer] Poise, competency, and success. I have a 12 year old on my webcast team that looks and sounds about 10, but when he's in the technical directors chair the rest of team knows Exactly Who's In Charge. It's amusing to me to see him light into a 20 something year old that's more than twice his size for playing with their cell phone when they should be watching their camera, but he mostly commands by earned respect and rarely has to raise his voice, even in the noise levels of a live webcast production. [Answer] History is full of teenagers and children who were official leaders and who did somewhere between zero percent and one hundred percent of the actual decision making for their groups, depending on various factors. For example Francis II (19 January 1544-5 December 1560) Dauphin of France, reached his legal majority at the age of 14 in 1558 and became King of France on 10 July 1559 aged 15 years 5 months and 21 days. But he let his mother and the Guises make the decisions. On the other hand, King Edward VI of England (12 October 1537-6 July 1553) had his age of legal majority set at sixteen, and so never reached it. But he had a considerable influence on the policies of his regents as he grew older. And the difference is due to their different personalities. But they were hereditary monarchs. Who would follow the orders of even the bossiest or most competent child or teenager who was not their hereditary monarch? It is believed that the ancient Germanic and Norse people didn't have any role for minors to inherit the thrones. In 575 Childebert II became King of the Austrasian Franks age 5 when his father was assassinated. When Clovis died in 511, his four sons became kings, the youngest three aged about 16, 15, and 14. Clovis himself became king in 481 aged 15. Athalaric (516-534) inherited the Ostogothic throne in 526 aged 10. So there are examples of children inheriting Germanic kingdoms in the 6th century and of teenagers doing so in the 5th century. According to the Roman History of Cassius Dio, book LXXII, in about AD 170: > > Marcus Antoninus remained in Pannonia in order to give audience to the embassies of the barbarians; for many came to him at this time also. Some of them, under the leadership of Battarius, a boy twelve years old, promised an alliance; these received a gift of money and succeeded in restraining Tarbus, a neighbouring chieftain, who had come into Dacia and was demanding money and threatening to make war if he should fail to get it. > > > <http://penelope.uchicago.edu/Thayer/E/Roman/Texts/Cassius_Dio/72>\*.html[1](http://penelope.uchicago.edu/Thayer/E/Roman/Texts/Cassius_Dio/72*.html) Since this was centuries before the earliest known examples of Germanic child monarchs, I don't know if Battarius inherited his leadership or earned it somehow. in the US Civil War, many thousands of men were commissioned as officers in the various armies and navies. And most of them were men almost old enough to be the fathers of the typical soldiers, who were mostly young men in their twenties. But a few of the officers were very old, and a few of them were very young, but somehow managed to command positions. Most Union soldiers in the Civil war were members of jointly controlled federal/state volunteer units. Volunteers would be organized into companies and regiments by states and territories. They would be mustered into federal service and then paid and supplied by the Federal government. The men would often elect their officers who would be commissioned by the state or territorial governments. The federal government only commissioned general officers or officers in the rarer federal units. The Provisional Army of the Confederate States of America was formed in a similar way. Because the majority of the Civil War units were such volunteer units, most of the officers, especially at first, commanded because their subordinates had agreed to obey them, often by elections. At the beginning of the war the officers and non commissioned officers were usually not imposed on the privates by outside authorities, but chosen by the privates from among their friends and members of their communities. During the Civil War, most companies had only one first sergeant, six sergeants, and four corporals in their tables of organization, and most or all of them had command duties. Thus it was much more impressive to be promoted to those ranks, especially corporal, than it is at the present time. For example, Thomas P. Gere (December 10, 1842-January 8, 1912) was a lieutenant when he earned the Medal of Honor at the Battle of Nashville on December 16, 1864, aged 22 years and 6 days. That's doing pretty good as a young officer, right? Actually Gere enlisted in the Fifth Minnesota Volunteer Infantry, and was mustered in January 17, 1862, and was promoted to first sergeant and then second lieutenant. His company was stationed at Fort Ridgely, Minnesota, when the Minnesota Sioux uprising started on August 18, 1862, and Captain Marsh and many of the men were killed trying to rescue civilians. This left Lieutenant Gere in command, age 19 years, 8 months, and 8 days. Lt. Timothy Sheehan (age 21) arrived with reinforcements before the Sioux attacked on August 20 and 22. Lieutenant General Arthur MacArthur Jr. (June 2, 1845-September 5, 1912) enlisted in the 24th Wisconsin Volunteer Infantry and was commissioned a first lieutenant and adjutant August 4, 1862, aged 17 years, 2 months and 2 days. At the Battle of Missionary Ridge, November 25, 1863, thousands of Union soldiers ran up the ridge without orders to drive away the entrenched Rebels at the top. Lt. MacArthur was one of the leaders in that attack, carrying the regimental colors and planting them at the top of the ridge, age 18 years, 5 months, and 23 days, and was awarded the medal of honor. He was promoted to major January 25, 1864 aged 18 years, 7 months, and 23 days, and to lieutenant colonel May 18, 1865, aged 19 years, 11 months, and 16 days. MacArthur was thus called "the boy colonel". Henry King Burgwyn, Jr. (October 2, 1841-July 1, 1863) also became known as "the boy colonel" (of the Confederacy). He was commissioned lieutenant colonel of the 26th North Carolina in August, 1861, aged 19 years and 10 months, and colonel in August 1862 when still 20. Uriah Galusha Pennypacker enlisted in the Union Army in 1861 and rose from private to quartermaster sergeant. He recruited a company for the 97 Pennsylvania volunteers and was commissioned captain in August 1861, and Major in October. He was commissioned colonel August 15, 1864, and led a brigade. He was promoted to brigadier general, United States Volunteers, April 28, 1865, and after the war he became a colonel in the regular army in July 1866. Various sources said that Pennypacker was born June 1, 1844, making him a Major aged 17 years and 4 months, a colonel aged 20 years and 4 months, a brigadier general aged 20 years and 10 months, and a regular army colonel aged 22 years and 1 month. Other sources say he was born on June 1, 1842, thus making him two years older when he achieved those ranks. Charles Cleveland Dodge (September 16, 1841-November 4, 1910) was commissioned a captain in the 7th New York Volunteer Cavalry in December, 1861, aged 20 years and two months. He was promoted colonel August 14, 1862 aged 20 years, 10 months, and 19 days, and brigadier general USV November 29, 1862, aged 21 years, 2 months, and 13 days. He resigned in June 1863 but led militia against draft rioters in New York City the next month. Ulrich Dahlgren (April 3, 1842-March 2,1864) was commissioned a captain on May 29, 1862 aged 20 years, 1 month, and 26 days, and a colonel July 24, 1863, aged 21 years, 3 months, and 21 days. Many accounts of young Rebels claim that T.G. Bean recruited and trained two companies of recruits in 1861 aged 13 before joining the Rebel army 2 years later. But he was actually Thomas Greene **Bush**, born 19 august 1947, and he was about 16 years and 11 months old when becoming lieutenant and adjutant of the 62nd Alabama regiment in 1863, and 17 years, 8 months, and 15 days old when they surrendered on May 4, 1865. W. D. Peake (born December 22, 1846) enlisted in Company A, 26 Tennessee Infantry (rebel) and was promoted to sergeant sometime before the war ended in April and May 1865 when he was 18 years and 5 or 6 months old. Henry Weidensaul was probably born July 1, 1847 and enlisted in the 46th Pennsylvania Infantry in 1861. He was promoted to Corporal May 18, 1863 aged 15 years, 10 months, and 17 days, to sergeant October 1, 1864, aged 17 years, and 3 months, and to first sergeant on July 1, 1865 aged 18 years. There is a possibility that a James H. Deal became a Rebel lieutenant aged about 13 to 18 but there is no proof of his service. There is a story that a T.D. Claiborne was born in 1847 and became a captain in the 18th Virginia Infantry in 1861, a Major and a lieutenant colonel in 1863, and died in 1864. However, there also a statement that Captain T.D. Claiborne of the 11th Viginia was born December 25, 1835. John C. Delany was born April 22, 1848, and enlisted March 5, 1862, in the 107th Pennsylvania Volunteers and apparently promoted to corporal aged fourteen years, eight months, and thirteen days, sergeant sixteen years, five months, and twenty four days, first sergeant sixteen years, eleven months, and seven days, and second lieutenant aged seventeen years, one month and five days, and earned the Medal of Honor aged sixteen years, nine months, and fifteen days. Gustave Albert Schurmann was born February 4, 1849 and enlisted in the 40th New York Volunteers in 1861. He was apparently promoted to sergeant in 1863 around the time of his 14th birthday. An E.G. Baxter allegedly enlisted in the 7th Kentucky cavalry (Rebel) aged about 12 and was commissioned an 2nd lieutenant when aged 13, but I have not found any record of that officer. Musician Charles Edwin King was probably born on April 3, 1849, enlisted in the 49th Pennsylvania Volunteers September 12, 1861 aged 12 year, 5 months, and 9 days, and died of wounds on September 20, 1862, aged 13 years, 5 months, and 17 days. It has been claimed that he was promoted to drum major during his service. John Lincoln Clem (August 13, 1851-May 13, 1937) of the 22nd Michigan became one of the most famous drummer boys in the Civil War. He was promoted to the little known rank of lance sergeant on September 20, 1863. Thus he became a non commissioned officer aged 12 years, 1 month, and 7 days. A Charles Carter Hay claimed to have joined the 15th Alabama age 11 and to have been appointed a lieutenant and a captain, but there is no record of such an officer. Gilbert de Motier, Marquis de Lafayette, (6 September 1757-20 May 1834) was commissioned a Continental major general on 31 July 1777, aged 19 years, 10 months, and 25 days, though he didn't receive large commands suitable for a general until he was 20. So there are some examples of young leaders who people followed from history. [Answer] The four main qualities that contibute to ending up in a leadership position are: Knowledge, Leadership, Luck, and Appearance. Knowlege of the relevant issues that impact the community, or the ability to listen to good advice on those issues. Having good leadership skills, being able to give orders in a way that commands respect instead of foster resentment. Being in the right place at the right time, Dumb luck and strange coincidences have been major factors in many people ending up in leadership positions. The last one is that you need to Look like a leader, or be able to command respect through appearance alone. (Warren Harding was one of the least qualified presidents of his time, but was elected anyways because he looked presidential.) Anyone could become a leader by having even 1 of these 4 qualities, but for someone to be a good leader you may need to have 2,3 or even all 4 of these qualities The character you describe may have a hard time looking like a leader, or may not have a wide pool of knowledge, but with the right leadership skills could still earn enough respect to end up in charge of a community. [Answer] A nineteen year old can look quite adult, especially behind the usual dirt, facial hair and attitude changes that tend to come after an apocalypse. There's no need for anyone to know he's an adolescent. Espacily if he's not necessarily a paragon of virtue. Alternatively you could lean into his adolescence trying to lead in hard conditions when many of the people beneath you think that you're "actually just a kid" is a hard struggle. Generally in writing struggles for your protagonists can be embraced, I personally would read about a child ruler desperately juggling internal politics, managing subordinates and rivals alike regardless of any zombies. Finally its possible you don't even need a justification, the walking dead is primarily a world gone mad. Child rulers have exsisted in the past and I'd happily follow a twelve year old in twd [Answer] If he was of greater stature that those around him (say 6'4", 220 lbs), and was competent at keeping himself alive, protecting his people and keeping them fed, his age would be a minor nitpick. He would be someone that most everyone would have to, literally, look up to. That goes a long way towards "leadership" material. [Answer] Kids and teens have lead things before. In WW2 Yevdokiya Zavaliy hooked up with a calvery unit headed for the front at 16 by 17 she was commanding her own machine gunning platoon she won 40 medals for her command and bravery under fire. Frau Black Death was her war name, she made her men, who initially were not happy with a teenager for a leader, fall under her command quickly due to her actions, tough discipline measures and bravery under fire. Her unit soon became a routine go to for front line heavy fire and difficult battles as they were fearless and maintained themselves well under such conditions. I forgot the war down in South American in the 90s were two young girls (twins) became commanders of a forest rebel group holding supreme iron fist rule they were only 10 so why? Partly local village legend had them being war gods due to their twinship the other part? They'd shoot you so much as look at you. When they were interviewed they came across as adult grizzled war vets in demeanor and attitude. So your person needs to eventually be the most capable and cool headed leader in the group when the tirbe needs him even if they weren't looking at him at to him at the very beginning. It might be even better if his traits come out slowly the group take notice when the group favored say two others for the job but issues weren't always going thier way. It helps if they have some bravado if they have to kill the former leader and have tact as well. If they inspire, organize people well, make them feel like they're contributing to the mission, their society, and maybe slip in a bit of undetected manipulation he could go far. Think of the qualities you like in a leader or what historically would be required? The group needs security, food, shelter, but as this group wants to get larger and larger they need a relative safe zone for rearing and having children and those children having some success of survival. Your kid could've been brought up with critical thinking and practical application skills at first this is what makes him more qualified or his willingness to infiltrate the enemy and blow up things without support it depends on what his tribe needs from a leader in the time it is required he can grow into the other traits that make them feel confident, strong, and willing to allow him to lead. ]
[Question] [ So I'm creating an original world with a number of creatures, and original peoples. One of the peoples has a two-speak language. One element, the base of the language, is based off of local mythology, the second a form of sign language. The base of their language would be stories about creation, or explanations of their traditions. The sign language would help specify the story for the instance they are in, and to communicate with one another. My question is how would this come about? How would it evolve, as in what reasons might cause this to occur over a single speaking language like most cultures have. Would it be too difficult a form of communication, and would it make more sense to focus on one element over the other? Maybe take the spoken language and replace it with clicking/whistling? Edit: These are humanoids, in fact they are human. They have two arms. Their culture is a mixture between Native American, and African. They live in an oasis within a very large desert. This oasis, is accessed through a cave, from the desert, where the oasis consists of five tribes within this culture. They are very tribal, and do not take to outsiders. They sometimes leave the oasis, where they interact with humanoids that are much faster than them, and stronger. As well as having to deal with large, humanoid-insects, torso human-like, bottom of the insect. (they come in many sizes, and types.) The oasis itself is much like a paradise, and they do not have to worry much, save for bad juju. The language is one. Not two, but like that of a two tier system. In idea. I got this idea from a Star Trek episode actually. I wanted to further it. [Answer] > > My question is how would this come about? How would it evolve, as in what reasons might cause this to occur over a single speaking language like most cultures have. Would it be too difficult a form of communication, and would it make more sense to focus on one element over the other? Maybe take the spoken language and replace it with clicking/whistling? > > > Spoken language is used because it's more powerful than sign language. What you need, also given the human stock of your people, is a powerful reason **not** to use speech except at a bare minimum. The simpler reasons that come to mind are that either your humans need to communicate often with a subset of themselves who don't have speech (a bit like the Old Language of *Ayla* by Jean Auel). It doesn't sound very convincing though. ...or using spoken language at length is **dangerous**. Perhaps, some kind of predator - or a swarm of insects - that hunts by sound?. Sort of like any rhythmic sounds weren't really recommended on the surface of Arrakis, lest you became Shai-Hulud's dinner. So, your people would need some "language" shorthand with enormous information density, where a whole plan of action could be conveyed with a very short burst of sound referencing a vast corpus of shared knowledge - such as "*Darmok and Jalad at Tanagra*" (or more like Asimov's *robot-speech* used between R. Daneel Olivaw and R. Giskard Reventlov). This could evolve naturally from recounting past heroes' exploits, and having an eye for recognizing patterns. Then you could have a rough tactical planning session employing almost no sound, and some hand gestures. Like the Tamarians, our humans would just need to state the bare minimum to indicate what scenario they're referring to. The full spoken language would still be used in the safety of the inner caves (also to *teach* those stories), and maybe would grow to have an almost holy quality, while the safe, rude and simplistic day-to-day sign language would be used in the open. They would perhaps develop funny figures of speech - "this is more foolish than making speeches in the light of day" - "he's so paranoid he'd finger-spell in a locked room" [Answer] **Most communication via spoken language includes more than the spoken component.** Humans already have a non-verbal aspect to our spoken language. Body language, gestures, and facial expressions. If your aliens only used the verbal aspect they'd likely end up as confused as humans can get when we communicate via text only. Otherwise there are plenty of reasons such a system might evolve. Perhaps they have poor hearing or require touch to be able to verbally communicate. This would mean sign language is for strangers. Perhaps it's a cultural reason. We use latin for medicine because it isn't used by the general public, this way words like "literally" don't suddenly also mean the opposite because of popular misuse. If your aliens use spoken language more loosely but signing is very precise, there is good reason to have both. [Answer] **The problem is information density** Sound can be manipulated in far more ways than your body can. Consequently, you can convey more information more quickly with sound than you can with body language. Now, you didn't tell us the tech level of your species nor did you describe their physiology. Let's assume they're human. Humans can process a vast amount of information visually, but we can't wave our hands fast enough to beat speech. But let's say we have four arms (curse you [John Carter](http://movieslutreviews.blogspot.com/2012/03/john-carter-of-virginia-mars.html)!). Now you've doubled the information density of body language. Combine that with a simpler life (e.g., pre-renaissance), and I could suspend my disbelief and accept dual-mode communication. But, we want [flying cars](https://www.youtube.com/watch?v=vzm6pvHPSGo)! Now we need a reason to reduce the information density of the spoken word. One way would be to evolve a tongue or a throat that makes complex sound more difficult. Another way would be to add something to the atmosphere that dampens sound (either making speech beyond a foot hard to hear or that forced the ear to evolve with much less sensitivity to protect itself). OK, now we have a reason for dual-mode communication and we still get flying cars! But it's not enough! I want to hear that pin drop! The only thing I can think of would be for the body language mode to not represent a complete language. Instead, it would represent inflection (as we do in spoken speech) such that (e.g.) a hand waving to my left would mean I'm being sarcastic... etc. This would actually add quite a bit of depth to spoken language — right up until you need to communicate with pilots or anyone else via radio, then the body language element would most likely disappear (in a similar manner to cursive writing in U.S. schools, it's simply not needed anymore, so it's becoming an anachronism). [Answer] **Have an external factor influence their language** > > [...] the base of the language, is based off of local mythology, [...] stories about creation, or explanations of their traditions. > > > As you state their spoken language consists of mythological stories, etc. depending on the mythological basis and societal evolution this might even be [scripture](https://en.wikipedia.org/wiki/Religious_text). Thus they speak in references. This by itself seems to be fine and interesting enough, but why would they do that instead of talking plainly? The answer to that is by providing some external force, real or imaginary, that compels them to follow up on this practice. You mention, > > [...] they do not have to worry much, save for bad juju. > > > So let's pick up on the *bad juju* part. Have their religion/mythology contain a god or similar body that requires them to only ever talk in references/stories when speaking out loud. Taking the angle from mythology said god would not be almighty and thus might not pick up, or simply not care about other means of communication - so for their daily exchange your people(s) developed sign language(s) to complement their vocal exchanges, so they do not blaspheme. [Answer] This reminds me of a novel I read a while ago, but I forget what it was and what the exact context was. But in this novel, there were Neanderthals or something that spent a lot of time in space suits. It made more sense in the book. But, these Neanderthals used a lot of signed language because in space, no you can hear you talk. So one way to force a society to regularly use two modalities is to figure out some reason why they couldn't speak/hear one another regularly. Going off of your setting, it could be too loud in the desert due to wind (although the sand being blown around might make it hard to see too), or they could use signed language to avoid the beasts with very sensitive hearing them talk while outside. [Answer] In most languages today there are actually dual ways of saying things, with a subtly different meaning. Most latin-based languages have a formal and informal setting. For instance, in Italian: * "Lei" means politely 'you' * "Tu" means 'you' informally In Mandarin, inflections in similar sounds (for instance having a stronger 'u' inflection at the end of a word instead of a soft 'u') completely changes its meaning, as another example: * "Shu" = yes * "Shu`" = rat What does the above mean? Languages are not consistent, and actually very complex even when you just look at spoken language alone. Saying a similar sound differently may give completely different meaning, or the same meaning can be communicated with different sounds. Now have a look at the Ancient Egyptian language. Many people don't know there was actually one language but two scripts: hieroglyphics and cursory: * Hieroglyphics: Used initially in the early dynasties, become then used by the priests as they became the only ones to learn it, then it became a 'divine' form of writing. * Cursory: As hieroglyphics was more convoluted to write, many started to short cut it and write loosely, eventually cursory script becoming the preferred written form. However, both Hieroglyphics and Cursory writing were still used at the same time for thousands of years, and the spoken language remained the same. It was just that cursory was faster to write. This strange duality of convenience could easily be translated in your case, instead of writing in 2 scripts, gestures in one, and speaking in the other. It would be easy to imagine physical gestures can be used to supplement meaning in a verbal message - actually the Italians already do that very well today using hand gestures to emphasise their speech (find an Italian, and ask them about their day). It may actually be an evolution of this, where gestures, instead of inflections in speech or alternate writing, could be used to influence the verbal language for the sake of convenience or formality, as in the examples above. [Answer] One thing is if they don't or can't easily read body language or subtle expression. In the Expanse books the people who live in the belt have a lot of hand gestures for things like nodding, shrugging, etc. because those motions don't work well when you are in a space suit. There are some humans who don't do well reading emotion or body language because of things like autism. So a way to express intended humor or anger non-verbally but also non-ambiguously would be very useful. If an entire race had trouble with this, then verbal only communication could be more difficult, and so a secondary sign language could develop to give extra visual meaning around the spoken conversation. [Answer] A two part language like this would likely evolve when it is for some reason important to *interfere* with communication. Which is kinda counterintuitive, since the point of language is to communicate. To make it work, in this scenario, there is a spoken language, the one they use to learn these stories/myths, and to speak plainly with each other, there is a sign language likely used for the same reason ours was made (to communicate when speech/sound is impossible or dangerous), there may well be other spoken languages, and/or other sign languages, there are multiple cultures with mythologies, religions, shared stories. They all have to exist as a background for how this two-part language is set up, how it evolves. This two-part or hybrid language is more difficult to track or understand than either a sign language or a spoken language - one must be looking *and* listening, one must pay attention to two flows of communication simultaneously, one must intuit how they interact with each other in support, in negation, and in supplement, all at the same time. Not easy, just think about trying to follow three or four conversations at once, and realize losing track of any is likely to mess with understanding the others, as well, since they interweave. And on top of that, the spoken part of the language is made even *harder* to understand by generously incorporating references to mythology and stories, culture, etc. This makes it very difficult to follow, only one knowing the right things, paying the right sort of attention, and with enough presence of mind to translate on the fly is going to get, even, most of what the one speaking is trying to say. In the end, this is set up to be as difficult to understand as possible... and so this kind of language will only evolve if there is a *reason* to be difficult to understand. A reason like trying to communicate with certain people at the same time/place as needing to *not* communicate with other certain people, who are there watching. There has to be a reason someone would rather risk misunderstanding or completely miss communicating with their target, just to be *sure* someone who isn't their target, will *not* understand. One reason might be oppression, war, slavery, other similar deadly troubles. A member of an oppressed people may well need to hide their communications, and not only will speaking in metaphor and reference hide depths of meaning, the use of a secondary communication route (the sign language) may let them negate or reverse certain parts of their speech, or emphasize them, or so on, so they can sound like they're saying one thing to those listening, while sneaking a second communication under others' noses. In this case, intercepted communications is a life-or-death matter, so the more layers of misdirection they can come up with, the better. Another reason, a bit more lightly, might be rivalry between groups, competition, politics, etc. In this case, the references would be different for each group, different mythologies or emphasizing different stories within their mythology, based on which individuals, which stories or lessons their group related to... and the sign language would be different as well, depending on what kinds of things they wanted to reference, and what stories they were weaving their communication into. Intercepted communications may effect status, might spill secrets, might skew interactions between the groups, so it can be quite serious without being deadly. So, to wrap things up a bit, this double pronged language evolves in a scenario where there are multiple groups, multiple languages, and they are in competition with each other - so this evolution is a way to communicate with members of their own group, and confuse or deny communication with those who are members of different groups. This double language would begin as a pidgin of these two languages, used as a code or encryption, with set call-and-response pairs, to communicate specific things without being overheard, so to speak. Over time, it may evolve into a separate language of its own, a creole or a lingua fraca, even though the base languages would likely *also* be known, by the same people, for a very long time... by the time this double-language would stand on its own, it would have simplified the mythological references down to the bone, to be easier to understand, so to maintain that extra layer of references the base language must be available for plain speech. ]
[Question] [ I was wondering if you could possibly make a form of time measurement that would apply to a planet in a galaxy and then another planet that is ~20,000 light years away. I want a unit of time that, for both planets, will be a whole number. Also here's useful info about the first planet (the planet I've been working on)... 1. 1 year on the planet is 539 earth days. 2. Plants and trees are thriving. 3. There is a star that provides light about 150 million km away from the planet. [Answer] Simple an [atomic clock](https://en.wikipedia.org/wiki/Atomic_clock) > > An atomic clock is a clock device that uses an electron transition frequency in the microwave, optical, or ultraviolet region of the electromagnetic spectrum of atoms as a frequency standard for its timekeeping element. Atomic clocks are the most accurate time and frequency standards known, and are used as primary standards for international time distribution services, > > > In a bit more detail > > The actual time-reference of an atomic clock consists of an electronic oscillator operating at microwave frequency. The oscillator is arranged so that its frequency-determining components include an element that can be controlled by a feedback signal. The feedback signal keeps the oscillator tuned in resonance with the frequency of the electronic transition of caesium or rubidium. > > > The core of the atomic clock is a tunable microwave cavity containing a gas. In a hydrogen maser clock the gas emits microwaves (the gas mases) on a hyperfine transition, the field in the cavity oscillates, and the cavity is tuned for maximum microwave amplitude. Alternatively, in a caesium or rubidium clock, the beam or gas absorbs microwaves and the cavity contains an electronic amplifier to make it oscillate. For both types the atoms in the gas are prepared in one electronic state prior to filling them into the cavity. For the second type the number of atoms which change electronic state is detected and the cavity is tuned for a maximum of detected state changes. > > > You can also extend the idea into the realm of Quantum mechanics > > **Quantum clocks** > Further information: Quantum clock > > > In March 2008, physicists at NIST described a quantum logic clock based on individual ions of beryllium and aluminium. This clock was compared to NIST's mercury ion clock. These were the most accurate clocks that had been constructed, with neither clock gaining nor losing time at a rate that would exceed a second in over a billion years.[40] In February 2010, NIST physicists described a second, enhanced version of the quantum logic clock based on individual ions of magnesium and aluminium. Considered the world's most precise clock in 2010 with a fractional frequency inaccuracy of 8.6 × 10−18, it offers more than twice the precision of the original.[41] [42] > > > **Optical lattice clocks** The accuracy of experimental quantum clocks has since been superseded by experimental optical lattice clocks based on strontium-87 and ytterbium-171. > > > Essentially you need a super stable timer.. For relativistic effects, you could still caculate the offset of "normal" time as long as you know you speed. Just as the GPS system does. > > Einstein's general relativity theory says that gravity curves space and time, resulting in a tendency for the orbiting clocks to tick slightly faster, by about 45 microseconds per day. The net result is that time on a GPS satellite clock advances faster than a clock on the ground by about 38 microseconds per day. > > > [Answer] Sounds an awful lot like ZULU time (also known as Greenwich Mean Time) used by the military and various large internationally coordinated projects (like spacecraft positioning or aircraft direction). To avoid conflicts with time zones ZULU time is simply the time it is currently at the zero meridian on our planet. This way if you are say, ordering an artillery missile strike from one time zone into another on a target that will then be bombed by aircraft and assaulted by infantry being fed positional data from a satellite. These events and assets all ***NEED*** to be in the proper position at precise timing. If the bomber pilots taking off from an airbase 1000 miles away forget that "0600 sharp" is really noon where they are dropping the bombs white the satellite team is back home in Arizona where 0600 was 4 hours ago then it all goes awry. You got missiles hitting a target with troops standing by waiting 4 hours for the bombs to drop while the satellite is looking at the wrong part of the planet. If everybody synchronizes their watches on ZULU time then "0600" is going to be "0600" no matter what time zone the various assets involved are in. Maybe both planets could measure time by the rotational bursts from a pulsar. So each rotational outburst from the pulsar is equivalent to one unit of time and is then broken down into smaller portions for purposes of measurement (say 1 rotation equals a "stellar month" 1/10th of that time span is a "stellar week" and 1/100th of that rotational period is a "stellar day" and 10 rotations of the pulsar are a "year") Both planets keep their own local time measurements for unofficial purposes, but for purposes of timing communications with each other or sending ships back and forth or just any inter-stellar action that requires a high degree of coordination they could use the interstellar clock and date system to ensure they were both on the same page. [Answer] *Here's my answer, even though I realize that it may not be exactly what you want.* What is time? It is a way to define when events happen. Time has no real meaning in the universe; it is a unit of measurement made up entirely by and for humanity. Indeed, the idea of time has changed often from our first conception of it. Time used to be tied to the Sun. When the sun was directly overhead, that was noon. Time across the Earth was uneven and not constant. So noon in one town was 11:20 in another. But everything was fine, because the reach of the town's time-setter's influence was contained to that area. Then, when trains started coming though, they needed an accurate way to note time. Then when we needed incredible precision, they changed time to be counted not by our orbit, but by atomic particles (see other answers). I think for this you need to think out of the box. I don't think its as easy as defining a new minute or second, or even the transportation and syncing of it. I think you need to rework what time is, and what it means. Maybe go back to the old system of basing it off nature, like a pulsar. But in any case, like the kilogram, you should expect your definition to be fluid, and not exact. Time is relative, and its only function is to denote the passage of it. [Answer] You can measure time reasonably accurately, and at the same rate, at the individual locations, atomic clocks based on the same elemental oscillations being more-or-less equally accurate. Coordinating between locations tens of thousands of light years apart is more complex, the "easiest" answer is to use the signals from a repeating extra-galactic source, any strong radio source will do as long as it repeats regularly, an extra-galactic source is used to minimise issues relating to interstellar distance and signal arrival time agreement, 20,000 light years isn't all that much on an intergalactic scale, as long as you know the relative position of both points compared to the signal origin you can sync the clock time or at least get close enough that everyone thinks it's synced. The thing is that even having perfectly synced clock time at the two locations does nothing for you unless you have the means to communicate between the two sites in real time. If you have that kind of instantaneous communication it provides, almost by definition, a self-synced and internally consistent "comms time". All the users would need to do would be to agree on a universal definition of a "cycle time", probably again culled from atomic clock time, but they need that to effectively coordinate communication in real time anyway. As soon as that cycle time is agreed it constitutes a universal clock independent of the clock and calendar of any planet that uses the communications system. The point is that without instantaneous FTL communications "universal time" has little use and once you have communications at those speeds you have a universal clock whether you wanted one or not. For interest see also [Barycentric Dynamical Time](https://en.wikipedia.org/wiki/Barycentric_Dynamical_Time), the current standard for measuring time across relativistic divides based on gravitational positions and high relative velocities. [Answer] This answer assumes non-causality busting star drive is in play but.... **You could use Pulsars as Clocks?** By mutual agreement two or more widely separated planets can use one or several (results averaged) highly regular pulsars as a clock. They then have to agree on is a scale for counting them e.g decimal. So 100 pulses equals X unit of time, then there are 1000 units of X in the next unit up and so on. Once they have a scale worked however they still need an agreed start date for any official galactic 'calendar'. Perhaps the day light from a particular supernova first reached one of the planets would do. If not some other mutually recognizable event independent of both planets that occurred at a specific location is agreed upon. (Each planet can then calculate backwards to figure out how long ago that was in local time. This might give you a **Galactic Standard Time** but hey everyone ignores it and uses local time until its needed for some specific purpose e.g a time/date stamp at the top of a message being sent from one planet for another. [Answer] The other answers here focus on a more "realistic" way to answer the question, but here's some inspiration for a more creative solution. In the webcomic [Spacetrawler](https://www.baldwinpage.com/spacetrawler/) a galactic society has their time system synched with an interdimensional revolving door that no one can figure out how to use. Each revolution is a week and other units of time are p ]
[Question] [ Let us develop an industrial electric motor from first principles. [Alessandro Volta](https://en.wikipedia.org/wiki/Alessandro_Volta#Early_battery) developed a battery whose ingredients were copper, zinc, seawater, and imagination. These ingredients have been available since prehistory; his [voltaic pile](https://en.wikipedia.org/wiki/History_of_the_battery#Invention) was made in 1800. [Hans Christian Orsted](https://en.wikipedia.org/wiki/Hans_Christian_%C3%98rsted) developed the principles of electromagnetism in 1820 when he noticed that a compass was deflected by the current drawn from a battery. A year later, [Michael Faraday](https://en.wikipedia.org/wiki/Michael_Faraday#Electricity_and_magnetism), who knew Orsted, was able to make a wire rotate around a magnet. It took him until 1831 to explain what magnetic induction. With this explanation in hand, the amazingly named [Hippolyte Pixii](https://en.wikipedia.org/wiki/Hippolyte_Pixii) built an AC electrical generator. By 1844, the first [industrial application](https://en.wikipedia.org/wiki/Woolrich_Electrical_Generator) of an AC motor was made in a Birmingham factory. Is there any reason that this process could not have been carried out starting in 1600, had Volta made his discovery then. Perhaps it would not have gone so fast, but is it realistic that the first non-waterpowered factories of the late 1700s would be powered by electric motors. Or, put another way, **could electric generators have been available for factory work before steam engines?** [Answer] No, there is a lot more too it than that, a generator generates electricity. Electricity on it's own isn't much use, you need electric machines that use it, and some way to store it, which is a whole other matter and set of inventions. Electricity was around a long time before people found an industrial use for it. Steam and water power on the other hand have much more obvious and intuitive mechanical uses so you can easily repurpose existing technology to them. Gears, linkages and suchlike were already in use. Capacitors, resistors and all the rest weren't. [Answer] With modern knowledge we can adjust design to "down-tech" generator. For example, a multi-polar generator would not require a high rate of rotation. But, it took surprisingly long in 19th century to understand such simple ideas as self-excitation and necessity to lower internal resistance of generator (see history of Edison's long-legged Mary-Ann, [SA #41, pages 276, 305](https://www.forgottenbooks.com/en/books/Journal_-_Franklin_Institute_of_the_State_of_Pennsylvania_1878_1000273052)). Without a time traveler this knowledge has to be "mined" with spending great effort on thinking about theory and checking it. There would be little incentive for this -- unlike steam engine, generator does not "produce" mechanical energy, it is just useful for transfer of energy. While there was [some demand for this in 1600s-1700s](http://www.lowtechmagazine.com/2013/01/mechanical-transmission-of-power-stangenkunst.html) as well, it was much smaller. And even in 19th century, with all progress of scientific methods, and supply of energy, just begging to be transferred, it took some decades to understand electricity enough to make it useful. I would say that in a world with lots of atmospheric and animal electricity, lots of hydroenergy and little fossil fuels it has some chance to happen. [Answer] # Of course! ### Accumulators Accumulators are easier to produce. Volta's battery design could be complemented by a manual worker hot-swapping batteries to the electric engine, just in the same way in which a manual worker need to shovel coal inside the furnace for a steam engine to run. ### Alternators These are harder. Mostly because the transfer of mechanical energy to electric energy is a "recent" discovery. However, note that such discovery does not depend on the invention of a steam engine. The answer is **water turbines**. Mills, be it [watermills](https://en.wikipedia.org/wiki/Watermill) or [windmills](https://en.wikipedia.org/wiki/Windmill) or [horsemills](https://en.wikipedia.org/wiki/Horse_mill), have existed for a very long time. Some claim that Egyptians and Babylonians have been using them too. Gears too have existed for [quite some time](https://en.wikipedia.org/wiki/Antikythera_mechanism), with obvious implications that one could couple a watermill with a gearbox to increase the rotational speed derived from simply splashing water on the turbine. Finally, plug that to an alternator, and enjoy some good wattage. Fun fact: magnet-based alternators work both as electricity generating devices, as well as electric engines. If large amounts of power are not a must, any SE user could build that in their kitchen sink. --- --- EDIT for science-fiction aficionados, and not for long-lasting factory work. **Could some form of electric engine be invented with the knowledge from the XVII and XVIII centuries?** *Galvani and the Frankenstein's propulsion* Galvani's experiments on dead frogs showed that it is possible to activate muscles using electrostatic potentials. Previous studies on anatomy had made it clear that limbs move thanks to the action of pairs of antagonist muscles. The Frankenstein's propulsion works by using parts of large dead animals. For instance, the shark-propulsion uses dead sharks attached to the back, or the bottom, of a boat. Electrodes are inserted in the dead body, with the terminals in the desired muscle groups, and sealed with gum and wax. A simple hand operated mechanism, such as a wheel with a rotating lever, rhythmically discharges a Volta's pile via the electrodes, causing the antagonist muscles to contract asynchronously, hence generating movement. For instance, this could be used to make the dead shark flap its tail. The Frankenstein's engine lasts as long as the battery lasts and as long as the muscle groups don't start rotting. Injecting the veins of the animals with adequate preserving fluids may lengthen the life of your Frankenstein's engine. [Answer] # There is a way, but it would be impractical. First let's establish that steam engines use the expansion of water vapor to generate work. To use this as the basis for a steam generator without first inventing the steam engine (and modern steam generators are really just steam engines connected to induction coils), you need a thermoelectric generator. The principle behind thermoelectric generation happened to be discovered in 1821 by Thomas Johann Seebeck, after the invention of the steam engine, but not too far off. The problem here is that it would be more efficient to simply heat the generator directly than to heat steam and then use the steam to heat the generator. [Answer] I would say yes. An electrical generator needs mechanical movement to generate electricity. One could attach an electrical generator to a water wheel. One could connect an electric motor to that generator and effectively 'transport' power. A dynamo on a bicycle (I had one back in 1989, W. Germany) does not need a steam-powered generator to power the light on the bicycle. [Answer] # Electroluminescence If man had discovered electroluminescence before steam engines then the face of the world would have been different. Some naturally found electroluminescent material include: Naturally blue diamond, as well as some other chemical compound (source: [wikipedia](https://en.wikipedia.org/wiki/Electroluminescence#Examples_of_electroluminescent_materials)) Combining this with either animal based electricity or a primitive battery could enable the first artificial light sources to be made. If we then make this a quest similar to the quest for philosopher's stone in our history and potentially in a society where water and wood are rare, but where such compounds are easily available (either from meteors or volcanoes) then electricity could become the first technology to be studied and then developped instead of steam engine (which came from Northern England where water, wood and coal were/are abundant). ]
[Question] [ A sandcrawler is is a tracked vehicle about 40 meters long, 20 meters tall, and 15 meters wide. It has a thick outer hull for protection from the elements. It has eight sets of tracks, four abreast forward and aft for support. It is designed to operate in hot and sandy desert environments. In the Star Wars universe, this [vehicle](https://en.wikipedia.org/wiki/Sandcrawler) is the Jawas' primary means of transport around Tatooine. From an engineering perspective, how practical would such a vehicle be? I imagine that the high center of mass would pose stability issues, especially over uneven terrain, and the eight sets of tracks would severely limit speed. [Answer] Depending on what you want to do with it, it might be a good or a bad design. The number you give do not completely fit with the picture but don't sound so bad. So not giving it any from gives the following shape with a center of mass about 7.5 m above the ground. [![Schematic of the sandcrawler](https://i.stack.imgur.com/FsAYI.png)](https://i.stack.imgur.com/FsAYI.png) So do you have any change of tipping over in rough terrain? If you go nose first everything is probably ok, sideways gives more danger but not as much as you would suspect. The tipping point is if the Center of Mass (CoM) lays outside the base, this only happens after a tilt of 40 degrees as can be seen in the picture. [![Tipping of the sandcrawler](https://i.stack.imgur.com/ytYQ4.png)](https://i.stack.imgur.com/ytYQ4.png) So what is the ground pressure it has. To calculate this you need the weight of the crawler and the area of the tracks. For the area of the track I took half the area of the bottom. For the weight I took 140 time the weight of the [Maus](https://en.wikipedia.org/wiki/Panzer_VIII_Maus) as this is the biggest tank build and this is roughly how many times the Maus fits in the crawler. I think I am highly over estimating the weight since the armoured plating only has to be on the outside so I took half the weight, but you can use any number you want. So the ground pressure exerted by the crawler becomes: [![Formula](https://i.stack.imgur.com/jcBae.png)](https://i.stack.imgur.com/jcBae.png) Ok so this is a bit heavy but it is somewhere between a montouain bike and a road racing bike, [see this reference](https://en.wikipedia.org/wiki/Ground_pressure), wikipedia of course. If the weight reduced (which I think is logical) and add slightly more track surface the contraption seems feasible. Whether it is usable depends on the application. One note on speed, since it is such a huge mass with relative high CoM you need to take care of the inertia of the crawler. Any slightly tight cornering at higher speed will cause it to tip over. [Answer] The Sandcrawler is hilariously badly designed for any kind of realistic use. The fact that it is so thin from one direction means that the incredible weight of the thing would cause it to sink into the sand. We already had problems with sinking into mud and sand during WW2 with heavy tanks like the Tiger and the KV. And at least those had wide bottoms to spread out the weight which meant it didn't sink into the ground *as easily*. The Sandcrawler is 10 times the size with a terrible weight distribution. It would really only be usable on a planet with a hard rock surface. It would sink into any ground that was even remotely soft. And the biggest problem with the treads isn't that they'd be slow. Modern tanks can go quite fast with an M1 Abrams having a top speed of 60mph (96.5 km/h). The problem with the sand crawler's is that the treads are so close together turning would be a slow tedious nightmare. If used in warfare it would be a massive target as well and any attempt to armor it would only exacerbate the aforementioned issues. ]
[Question] [ My story happens in the near future on the research station located on [Callisto](http://www.space.com/16448-callisto-facts-about-jupiters-dead-moon.html), Jupiter's second largest moon. The mission has just started when the crew discovers an abandoned alien station. Whoever made it is dead or gone long time ago. There's not much useful things left but the scientists manage to get an understanding of alien's [synthetic biology](https://en.wikipedia.org/wiki/Synthetic_biology). How to prevent the sudden influx of alien scientific and technological knowledge from instantly advancing humanity's technology thus propelling my story setting from its near future into far future? I want people to learn some useful things, but not so much that they would instantly become too advanced. [Answer] Plenty of options for us to play with here. Perhaps the aliens' methods of bioengineering require elaborate infrastructure to be employed. Sure, now we know how to build synthetic DNA, but it requires quantum supercomputers that we don't know how to build to get the most out of it. Perhaps it needs a compound that's extremely difficult for us to produce. Knowing that you need metallic hydrogen to modify an existing species into a new form isn't much help if you don't have any metallic hydrogen lying around the place. The aliens database isn't fully decoded and/or was corrupted by long storage. Parts of the data are readable and can be acted upon, but it'll take a lot more work to dig out the rest. We may know how to build an oven, but we've only got two recipes to cook in it. The knowledge could be suppressed by dark and shadowy entities. A corporation that funded the expedition to Callisto could claim copyright over all the knowledge in the database, and only release the information in a steady trickle that suits their bottom line. Just a few thoughts. Make of them what you will. [Answer] > > Don't worry about people stealing an idea. If it's original, you will > have to ram it down their throats. - Howard H. Aiken > > > I wouldn't worry about immediate leap since the reality doesn't work that way. To use [Geoffrey Moore](http://www.geoffreyamoore.com/) technology adoption cycle there's several types of customers: [![The market](https://i.stack.imgur.com/SqAy3.png)](https://i.stack.imgur.com/SqAy3.png) * Techies - want to try new things, few & they don't have much money * Visionaries -Specific visions about future and budget to bring it to life * Pragmatists - Don't care about technology just want their problems solved * Conservatives - Buy whatever pragmatists are buying but after it proves itself * Laggards - resist technology So maybe your scientists deciphered a way to make biological computer, since it's a new technology which barely works, and current computers are superior to it nobody but few techies plays with it. After some time a visionary thinks about use for it, maybe helping people with spinal cord to walk again using modified version of your computer and starts a project/company to achieve it. Afterward some pragmatists discovers that it has a problem that only your bio computer could solve it and then mainstream adoption starts. It might take decade(s) until we start using biological rifles Check oversimplified cycle explained at Eric Sink article [act your age](http://ericsink.com/Act_Your_Age.html) And if you wan't some technology to be in very limited use just make it stuck in the [chasm](https://www.youtube.com/watch?v=NVfiF6mcMoQ), there are plenty of those in the real world. [Image credit](https://www.support.com/crossing-the-chasm-for-the-internet-of-things/) [Answer] The simplest, albeit cliche, way to approach this is simple: Some sort of conflict happens on the space station, whether due to synthetically engineered creatures roaming the station, the accidental creation of them by the crew, or something else - and either the knowledge or the station is destroyed, meaning we get *ideas* but do not have the means to replicate their technology exactly. [Answer] I don't believe you would really have to do anything. Imagine sending a book on modern computer engineering back in time a hundred years. I would guess they would be able to develop semiconductors sooner and maybe, just maybe, iterate a bit faster than Moore's law, but you wouldn't see the internet appear mere years after the knowledge in that book was disseminated. You always need infrastructure. You need the tools to make better tools to make still better tools. ]
[Question] [ *Meta note: This is not about a dome over a city, so this is not a duplication of those questions. Instead, this is about a building that is a dome in shape.* For precise reasons unbeknownst to outsiders, China has found an impressive expanse of solid bedrock, and has decided to build a massive dome. The dome has a few requirements: * Provide as much protection against traditional (non-nuclear) means of attack as possible *The dome doesn't have to stop every assault, just offer meaningful protection as much as can hoped to be achieved.* * Be as large as possible in size *The government hopeful at including a few dozen city blocks inside this dome* * Act as a modern castle, supporting government functions and some civilian functions *The facility should act as a refuge for the government to retreat to, and allow it to bring some amount of infrastructure and supplies into.* * Provide a reserved, empty central region *They want the center of the dome to be as large as possible an empty area that can be later repurposed as needed. It should be free of any support beams, etc.* * Provide a means of sealing the facility off *There should be a means to provide an air-tight seal to the facility.* The government doesn't care about things like windows (who needs them?), and nor is it particularly concerned with any other issue of creature comfort. The people need to survive (for a short time, at least) when sealed in the facility but they don't need to be happy. They want the facility constructed within 20 years. They have reached across the globe to architect firms to find the best minds to work on this project. The government discovered that the tallest buildings in the world (Burj Khalifa, Shanghai Tower, and Abraj Al Bait) cost \$1.5 billion, \$2.4 billion, and \$15 billion to make. They decided to set the budget at 10x this combined cost, \$190 billion. [This will make it the single most expensive building constructed in modern times.](https://en.wikipedia.org/wiki/List_of_most_expensive_buildings_in_the_world) They feel like this budget will go a long ways since they have access to cheap labor and no egregious concerns about worker safety during construction. When the architects asked if the government is willing to compromise on any of these points, they said that they were **willing to compromise partially on any of the requirements, but not entirely on any.** Over a dinner meeting, one of the government officials sketched this design for a suggestion for the architects to look over. [![concept drawing of dome](https://i.stack.imgur.com/L4aaR.png)](https://i.stack.imgur.com/L4aaR.png) **How close to this dream can the Chinese government reach?** [Answer] As a counterpoint to the posts by Rigop and Michael Karnerfors, building a dome does not have to be particularly expensive (certainly not hyper expensive) so long as you are clear on the parameters and what you can expect. As the two posters pointed out, no dome, or indeed any structure build from current or foreseeable technology can provide absolute protection from modern weaponry. In the realm of "conventional" weapons, there are massive penetrators designed to pass through layers of rock, concrete and gravel to pierce deeply buried bunkers like the Fordo nuclear facility. If that isn't going to be feasible, then nuclear weapons are available and quite scalable. During the Cold War, it was speculated the USSR had a regiment of SS-18 "Satan" ICBMs fitted with a 20 megaton warhead each. The role of this regiment was to convert Cheyenne Mountain into Cheyenne lake, and reduce other command centres in the continental Untied States (Like SAC HQ in Omaha Nebraska) into deep holes. Since brute force is usually an expensive option, there are also ways of creating shaped charges out of nuclear warheads (see [Atomic Rockets](http://www.projectrho.com/public_html/rocket/spacegunconvent.php) for details). Fending off a slug of liquid metal moving at @ 3% of the speed of light is not going to happen in the physical realm. OTOH, a lightweight dome supported by air pressure can cover a very large area. Buck master Fuller conceptualized a dome to cover Manhattan Island, and [Alexandre Bolonkin](http://www.nextbigfuture.com/2008/04/very-cheap-dome-protection-from-nuclear.html) has also written about very large air supported domes. [![enter image description here](https://i.stack.imgur.com/1Magx.jpg)](https://i.stack.imgur.com/1Magx.jpg) These domes can moderate the temperature inside the city, as well as eliminate the need for snow removal in the winter, or excessive rainwater flooding the streets and sewers in the summer. Other benefits are in the realm of communications (placing a node on the apex of the dome provides line of sight to everyone, for example). The cost savings in energy consumption and city services (no trees are going to knock down power lines in a storm, for example) will repay the cost of the dome over its lifetime. The long term savings in energy and other costs can be repeated over all the cities in China (or anywhere else, for that matter), providing some economic benefits for the cities and the nation. In terms of protection, this type of dome can certainly slow the injection of outside contaminants, including radioactive fallout, chemical weapons and aerosolized bioweapons, and even deflect the overpressure and thermal energy of nuclear weapons which detonate at a distance from the dome, making ABM defences more practical and feasible. So in terms of using a dome to protect your society, the real benefit isn't in passive defense against weapons, which isn't particularly feasible, but in eliminating costs and providing a real economic boost to the inhabitants of the city by reducing their energy consumption and costs of city services, providing more capital for them to save or invest. [Answer] # The best defence can become the best weapon, for the enemy In the olden golden days of World War II, when the enemy had no kind of precision bombing to use, this might have been a good idea. Today, not so much. The reason is that the enemy is quite good at "threading the needle" and putting ordnance in the same spot, many times over. Not only that but the enemy has also become quite good at bashing their way through solid rock. Even if you build this thing 15 meters thick, after 3 to 5 hits in the same place, they will have punched through. Now your defence has become a liability, because suddenly it is **raining down huge blocks of rock over your population**. The enemy now has the ability to bury your population under 15 meters of crushed rock. And even just assuming they punch holes in it, the enemy can now start sending quite nasty stuff down the hole, such as [thermobaric weapons / fuel air explosives](https://en.wikipedia.org/wiki/Thermobaric_weapon). Start a good fire down there and not only will that start using up oxygen and fouling up the air with toxic fumes that you cannot vent out, but the dome will start reflecting the shock-waves of those explosions and sending them back to the ground. Double trouble. In fact, the enemy might even consider dropping a small tactical nuclear weapon down the hole because you have provided the enemy with a very nice [containment](https://en.wikipedia.org/wiki/Containment_building). And again: reflected shock-waves. They can use a fairly small nuclear charge, maybe only a few kiloton because with the shock-waves bouncing back and forth, this will wreak utter havoc in the city. So a dome? No, that is probably a bad idea, because once your enemy turns your defence into their weapon, you have no escape at all. As I said in the comments: burrowing down into a mountain or the ground is much more preferable. Then you can go deep enough to not have this be a problem. [Answer] You try to bring back the old good castle in warfare. The thing is the castle is out of the game since guns are powerful enough to disintegrate them. Today's weapon are adapt to modern war so we don't have the giant canon we used to made but if you bring back castle they will come back and what you built in 20 years will be destroyed in a week. <https://en.wikipedia.org/wiki/Schwerer_Gustav> The biggest cannon ever made could pierce through 7 meters of concrete plus 1 meter of steel in one shot. How many shot will it take to take down your dome ? Unless you have a fantasy indestructible material to built it, it is a very bad idea on the military side. This is why nobody even try to build it in the real world, I know nothing in architecture. However it is a really cool idea. Your problem is find a reason to build a useless expensive giant structure but it is impossible to make people believe it will solve all the problems... oh wait => "LETS BUILD A DOME!" So in my opinion a project like this is possible if it is a symbole and nobody expect it to protect anyone. ]
[Question] [ In Star Gate, the Ori are notorious for keeping the tech level of their planetary subjects at or under medieval tech levels. It has been said (still looking for the exact source) that if everyone lived like an American it would take the combined resources of **4 Earth's**([link](http://persquaremile.com/2012/08/08/if-the-worlds-population-lived-like/)) to support our population. I have a space faring empire with many planets. **Assuming medical technology is exempt (so there are still fully operational ER's) and sanitation is better maintained (indoor plumbing would have to exist regardless of tech level...maintained by the govt. of course), at what tech level (or technology oriented) lifestyle would a planet of 8 billion people have to average?** **What other benefits would a space-faring society have if they spanned hundreds of solar systems?** **EDIT:** The civilization in question has Battlestar Galactica level technology. [Answer] I think you are missing something very basic about economics; you are assuming that resource consumption will universally go up as technology improves, when really that isn't the case at all. In fact economics is about making better usage of inputs to the point that there is actually more forested land today in developed countries than there was in the past, and not just because of NIMBY. As the world economy continues to grow and technology continues to improve then more people will be able to have access to goods and services at cheaper prices with less impact. This is already true, were we to be using technology of the past we already would not be able to support the number of people on earth, and there exists already technology today that theoretically would allow the earth to support into the possibly trillions of people, at least in terms of feeding them basic nutrition. With a developed space economy a lot of things are able to be moved off world that impact the ecosystem today. Mining and manufacturing, even some crop production depending on the transportation costs involved (a space elevator(s) (or if you are serious about stargates a stargate in orbit linked to one on the planet) would help with that) can be moved off world, as can energy production, among other things, all into orbit so that without any other worlds involved the standard of living on the planet can be greatly improved without further drains on the planet's resources itself; especially if there were shifts in social expectations and product design. Having many planets at ones disposal allows for further specialization and hopefully gains from trade to be made, it also really allows for larger projects to be undertaken that are out of reach of a single planet with its labor force and resources. So the average person may not be able to have their own private asteroid resort or something, but they might be able to afford going on a cruise that stops at various planets and see sights all over the empire. They could easily live a life that is in many ways better than that of the richest people today. As noted by the maps, fitting the people on the planet isn't a problem, and if the power and manufacturing is primarily off world and done by robotics people are going to be quite well off (assuming that is what the empire desires). [Answer] Summarized, their quality of life could be close to modern 21st century standards, or even beyond. If you look at [energy consumption](http://en.wikipedia.org/wiki/List_of_countries_by_energy_consumption_per_capita) per capita, you might notice that quite a lot of countries which are generally considered decent places to live (Switzerland, Poland, Hungary ...) consume power well below US figures. You don't have to use power like an average US resident to live with modern comforts. (If you check the Iceland figure, perhaps that's because of the harsher climate in the US compared to parts of Europe. See my note on settlements around the single stargate, below ...) Another issue is just how fast you're planning to wear your planet out. Without a Stargate, mankind has to get along with ressources from Earth or at best the solar system for a really long time unless we want to die out. That's both a question of non-renewable energy (like [petrochemicals](http://en.wikipedia.org/wiki/Petroleum#Consumption)) and [damage to the ecosystem](http://en.wikipedia.org/wiki/List_of_countries_by_greenhouse_gas_emissions_per_capita). With a Stargate, you can import raw materials, export waste, and switch planets if you have to. I believe that you could have several billion people on a planet like Earth for a very long time if they all agreed to a sustainable lifestyle. I'm not sure if I can explain it without sounding like a political rant, but I think you need to check your assumptions about tech levels and personal comforts. * You don't have to drive a SUV go fetch your morning coffee from a trendy franchise. Very few people have a legitimate need for a Sports Utility Vehicle at all. Take your bicycle to work (more healthy, too) after a decent breakfast with the family and kids. * Meat every day isn't good for you. A couple of times per week is more than enough. ([Producing meat](http://en.wikipedia.org/wiki/Environmental_impact_of_meat_production) means animals are fed with food which has to be grown somewhere ...) * You don't need a private swimming pool behind a single-family home in a [green city in the desert](http://commons.wikimedia.org/wiki/File:Aerial_view_of_center_pivot_irrigation.jpg). * You don't have to dump last year's mobile phone just because a new one came out. You might note that most worlds in Stargate have reached a very stable tech level, so they don't throw things away because of [built-in obsolescence](http://en.wikipedia.org/wiki/Planned_obsolescence). Grandpa's [Death Glider](http://stargate.wikia.com/wiki/Death_Glider) is still perfectly adequate for most purposes. Yet another factor is that most worlds seem to consist of a [single settlement](http://tvtropes.org/pmwiki/pmwiki.php/Main/Planetville) next to the gate. It makes sense, in a way, and it is one of the results of the gate technology. Multiple Stargates on one planet interfere with each other, so people settle within easy commuting distance of that single gate. Why go halfway across the planet to another continent if you can go through the gate next door to another continent on a different planet? [Answer] **Very high tech.** NASA produces a [book (free)](http://spinoff.nasa.gov/Spinoff2015/) annually about the spinoffs that we benefit from on a daily basis, from cosmetics to speaker sound systems; most are for industrial and government benefit. They include transport, health & medicine, consumer goods, safety, energy, the environment, industrial productivity, etc. However, like today, there are people living off of very, very little. I suspect the spinoffs from the advances made in science and technology investment will "bring the population" along with them, unless, as you stated, they are artificially kept down. But, like today, you will have the "haves" and the "have-nots" most likely. I like to hope, however, that this gap will shorten someday. [Answer] I think your question is actually in two parts; what is the carrying capacity of the Earth and how do we change it to house "x" number of people. Without any sort of technology, the carrying capacity of Earth is rather low for hominids. Nomadic bands with neolithic hunter-gatherer societies and technology could live rather good lives, but needed large areas of land to forage and hunt. Given enough technology and energy inputs, OTOH, you could probably house a trillion human beings on Earth. Indeed, even today you could probably house everyone on Earth in Texas, leaving the remaining surface area clear for farming etc. People living in Texas, Earth might be a bit crowded, but people living in Amsterdam, New York City or Hong Kong live in incredibly densely populated urban areas without too much difficulty... Since you stipulate BSG technology and access to space, then the constraints of energy and resources become moot. The current population of Earth could live in relative peace and comfort with modern American lifestyles (although as noted, you can live quite well with lower amounts of energy and resource consumption). The only true limits at that point would be heat rejection, as all the billions of people's machines and appliances release waste heat (due to thermodynamic inefficiencies) into the environment. Even then, if we can postulate BSG or Stargate lovels of technology, it might be possible to bypass thermodynamics by exporting waste heat via wormhole or similarly SFNal methods. Doing so would be tricky, since this violation of thermodynamics in essence creates a perpetual motion machine. [Answer] As always I'll try to throw Frank Herbert's *Dune* into the ring. Of course the technological levels in the mentioned BSG (I assume re-imagined) vs Dune are hard to compare. Both however are space faring civilizations with FTL capability, span multi-planetary systems and are the only (main) sapient race not counting artifical ones in their respective universes. The lifestyles and tech level pictured however differ greatly with the major distinction between the two being mainly in the technological developments. In the case of Dune that would be caused by self-imposed rules against hi-tech. The God Emperor of Dune later leads the major part of the population back to a basic agricultural level. But even BSG itself describes great differences between the colonies, with some planets being highly industrialized, educated, secularized others shown as poor farming colonies or deeply religious fundamental. My point being: The answer to the average tech level could differ greatly depending not only on postulated scientific progress but also on societal decisions how to live. Good thing is that this is a very simple point for you as writer and worldbuilder to fit the story to your needs. ]
[Question] [ I want to find out what's going on in another star system, but I don't want to go there. How feasible is it to just build a big telescope and take a look? Scenario: Earth does not respond to communications any more, and nobody who enters the system leaves again. Is it physically possible to build a telescope, presumably a multi-part array type thing, at Alpha Centauri that could resolve human-scale objects (anywhere between "people themselves" and "aircraft carrier") and give me some idea of what is going on on-and-around Earth? I assume the primary obstacle is *something something signal diffusion* meaning that a clear image of small objects doesn't actually survive the distance, or if this isn't the case, coordinating the movements of the telescope's component satellites over what is presumably a large orbital separation within the Alpha Centauri system. [Answer] Maybe. Probably not people. And not without some incredibly fine control and gobs of computing power. The hard limit is atmospheric conditions on Earth. --- According to the [Rayleigh criterion](https://en.wikipedia.org/wiki/Imagery_intelligence#Satellite), the resolution of a circular collector is a function of wavelength, diameter and distance. ``` resolution = 1.22 x wavelength x distance / diameter ``` To detect individual humans from above, let's say we want 50 cm resolution. Alpha Centauri is 4.3 light years away. The Earth's atmosphere is pretty transparent to visible light. How big does the mirror have to be? ``` diameter = 1.22 x wavelength x distance / resolution diameter = 1.22 x ~500nm x 4.3 light years / 50 cm ``` Your telescope has to be [4 light minutes](https://www.wolframalpha.com/input/?i=1.22+*+wavelength+of+visible+light+*+4.3+light+years+%2F+50+cm) in diameter or half the diameter of the orbit of the Earth. Oh dear. That's ok, all is not lost! Fortunately you don't have to make bigger and bigger mirrors to get the job done. Others have mentioned [multiple array telescope](https://worldbuilding.stackexchange.com/a/12373/760) concepts. It can get weirder. [SciShow recently did a piece on space telescope concepts](https://www.youtube.com/watch?v=kdo0pqh2PXA) to drastically improve resolution without having to build bigger and bigger mirrors. One is a [giant umbrella](http://www.colorado.edu/news/releases/2015/01/23/new-space-telescope-concept-could-image-objects-far-higher-resolution) which would take advantage of the diffraction of light waves around the edge of an object to focus the light. The other is to carefully position glitter ... sorry... ["smart dust"](http://www.rit.edu/news/story.php?id=51127) to form a giant mirror in space out of what are essentially tiny reflective pixels. The light pressure from lasers would be used to carefully nudge the particles into position and keep them there. --- Then you have the problem of focusing a planet going around the Sun at 30 km/s in a elliptical orbit. That means you don't just track it in a straight line, you have to track the curve of the orbit as well. Once you do that, you have to track a person on the surface rotating at 450m/s, again curved. The math isn't that hard, and since you're so far away you have to turn your telescope very little, but the minute and constantly changing motion of your telescope required is extremely difficult to resolve down to a few meters. This is why we don't point the Hubble at the Earth. [DSCOVR](https://en.wikipedia.org/wiki/DSCOVR), the recently launched telescope we *do* intend to point at the Earth, will sit at the Sun-Earth L1 point 1.5 million km away and is only intended to do atmospheric readings. Fortunately for our 4 light minute wide space telescope, this is all predictable! Each piece can focus their local element individually without having to communicate with the rest of the telescope. No internal FTL communication required. --- Atmospheric conditions are your ultimate limiting factor, the problem of atmospheric haze. Even on the clearest day, the atmosphere reflects and diffuses light making your image fuzzy no matter what you do. This is part of the reason we put telescopes in space. But it is [mostly transparent to certain wavelengths](http://earthobservatory.nasa.gov/Features/RemoteSensing/remote_04.php). Visible light is one. Microwaves are much better, but humans and aircraft carriers don't emit microwaves. Also the longer your wavelength (microwaves are pretty long) the lower your resolution. Scientists have been studying [the problem of how to get good resolution through an atmosphere](https://en.wikipedia.org/wiki/Astronomical_seeing#Overcoming_atmospheric_seeing) for a long time and have come up with some very, very clever ways to overcome the problem. The whole is covered under [adaptive optics](https://en.wikipedia.org/wiki/Adaptive_optics). But that's for looking out from inside the atmosphere. We want to look *in*. Fortunately we don't have to run the numbers, [we have had spy satellites which can do this since the 60s and 70s](https://en.wikipedia.org/wiki/KH-11_Kennan). They're good enough to see aircraft carriers and people through the atmosphere, a sufficiently large array at Alpha Centauri *probably* is, too. But I don't have the numbers. The other place to look for information is in speculation about viewing exoplanets. --- You will be seeing 4.3 years into the past. You might think "great, then I can see whatever caused the Earth to stop communicating years ago", no. Information can only travel at the speed of light, so your information that there is a problem on the Earth would also be 4.3 years old. Even if at the moment you realized there's a problem on Earth you swung your super telescope to look, you'd still have missed the event. Best you can do is see the aftermath. --- What you can definitely do is gather data to theorize about what happened. For example, if you see a lot of atmospheric dust that could indicate meteor strike or nuclear war. Spectral analysis could tell you if there's a sudden increase in any elements in the atmosphere. Changes in albedo could tell you similar things. Color shifts could tell you if there was a massive plant die off (or if it goes the other way, [Triffid attack](https://en.wikipedia.org/wiki/Triffid)). This is how we make guesses about exoplanets right now, just from a few smudged pixels. With all that time and effort to get what will probably be a hazy image of what happened 4 years ago (plus time to make and focus the telescope), it might be best to just pack up the family car and take a road trip. Of course by then it will have been at least 8 years. But at least you can pick up souvenirs. [Answer] Use [Multiple Satellite Imaging](http://www.wikipedia.org/wiki/Multiple_Satellite_Imaging). NASA has already planned a "Planet Finder." The basic idea is that the more telescopes you point at a place the finer image you get, enabling you to zoom in more....I suppose you could set up a system of thousands (maybe hundreds of thousands or millions, but I don't have time to do the math) and see the surface of a planet. Rig them up in the outer reaches of the Alpha Centuri System and you can probably zoom in to a huge degree. The biggest problem I see is that you won't have a clear idea of what is actually happening as Alpha Centuri is 4.367 light years away. If you have the ability to reach alpha centuri in a timely manner then it would probably be easier to send a small team and have them send a signal back (assuming you have figured out how to instantaneously communicate with other star systems) [Answer] Realistically speaking, I see four major problems with your situation. 1. Alpha centauri is [4.3 lightyears](https://www.google.ca/search?client=ubuntu&channel=fs&q=how%20far%20is%20alpha%20centauri&ie=utf-8&oe=utf-8&gfe_rd=cr&ei=qSsMVaW8Hav_sQfr3oDwBg) form Earth. so you should see what happens 4 year earlier. Which can actually make for a pretty interesting concept. 2. The second big problem is that the telescope needs to stay fixed on earth (or worse, on a particular city). As you pointed out in your question. This feat seem almost impossible considering the distance, as a fraction of a degree would spell the difference between looking at Earth and looking at Pluto. But it is theoretically possible. Distin's idea of using many telescope might help on that regard. As the redundancy could be used to recalibrate the telescopes in real time, cover for errors and reconstruct a better image afterwards. 3. The last point concerns seeing through the atmosphere. The reason Hubble is located in space is that the atmosphere blurs image. This, along with point number 2, would probably make seeing a distinct city completely impractical. This would probably also prohibit the use of many telescopes like Dustin proposes. [This site explains it quickly.](http://hubblesite.org/the_telescope/hubble_essentials/) This is not really a problem if you wish to see what's happening in space. 4. The telescope would need to be incredibly powerful to clearly see all the way to Earth. Which also implies it would be incredibly massive. Today's telescope do not allow us to see any kind of details of something smaller than a star. I'm afraid I can't give more precise guess at how big it would need to be. Dustin's idea makes this point a little better as the individual telescopes can be smaller. More powerful telescopes need to be bigger and/or longer. Diagrams on [this site](http://www.raleighastro.org/observing/general-articles/102-purchasing-a-telescope) shows a few ways how telescopes are made shorter. Yours could probably be the size of a small moon by itself. If you want to build such massive tool, the only realistic way would probably be a [liquid mirror telescope.](http://en.wikipedia.org/wiki/Liquid_mirror_telescope) Where the mirror is a rotating pool of reflective liquid. Those are used in the real world because a curved mirror of this size has higher risk of breaking under it's own weight. In your case, this is not as important as you would realistically be in space. But the size of the required mirror (and lenses) make those hard to craft in the first place. Either because they need to be crafted in space or because you need a massive amount of material to craft it. In summary, building such a telescope might be possible and pretty interesting. Using it to see clearly enough in space would be theoretically possible but extremely complex and probably would not detect something smaller than a small moon. Going through the atmosphere is so complex that it seems simply impossible to me. [Answer] Here's another take on showing just how improbable it is to actually see a planet the size of Earth with any kind of clarity. I'll use existing telescope information to get an idea of the power of future tools. Then I'll look at the kind of magnification we need to see Earth. The bottom line is that you'd need much better technology than what we have now (or custom epic-scale hardware) and you probably wouldn't realistically get the level of details you expect. Bear in mind that I am in no way a telescope expert (these researches actually taught me a thing or two) and my knowledge of the finer details of telescope working is lacking. **What we can see now** I'll use Hubble as a point of comparison for image quality. The [James Webb telescope](https://web.archive.org/web/20150403164057/http://jwst.nasa.gov/comparison.html) is meant as the next space telescope, with launch due in 2018. According to the link, Webb is 17 times larger, has a collecting area 7 times larger. For a field of view 15 times larger and a "significantly better spatial resolution than is available with the infrared Spitzer Space Telescope". I know that we can't equate the field of view with resolution. But I'll assume it can translate relatively well if the telescope was made specifically for resolution. From that, I'll assume that raw power of your telescopes to be around 50 times stronger than Hubble. **How to detect an exoplanet** Even without catching details, how can we just confirm that Earth still exists? Turns out that most exoplanets are [indirectly detected](https://en.wikipedia.org/wiki/Methods_of_detecting_exoplanets#Established_detection_methods) instead of actually being seen. There is, however, a [list](https://en.wikipedia.org/wiki/List_of_directly_imaged_exoplanets) of directly imaged planets. The good news is that some are a lot farther than Alpha Centauri. The bad news is that the smallest is above Jupiter size. Moreover, if you look at the pictures of those planets. All we can see are speck of light. [This](https://en.wikipedia.org/wiki/2MASS_J04414489%2B2301513#/media/File:Brown_dwarf_2M_J044144_and_planet.jpg) and [this](https://en.wikipedia.org/wiki/HD_95086_b#/media/File:VLT_image_of_exoplanet_HD_95086_b.jpg) picture are among the clearest I've found. This view of [Beta Pictoris b](https://en.wikipedia.org/wiki/Beta_Pictoris_b) is annotated and can give you an idea of the scale we're dealing with. If those images were magnified 100 times because of technological advancements, we could definitely "see" Jovian planets. But Earth-like planets would look like current images at best. **Possible but unrealistic** In the end, the magnification needed makes it theoretically possible to see what's happening in space. It would be possible if: * What's happening is on the scale of Jupiter or a Dyson sphere. This object would be visible in the same way exoplanets or secondary stars are visible. * What's happening emits a distinct form of radiation. Maybe a pattern is visible in non-visible light or it emits a special kind of radiation. This is basically how we detect neutron stars. * Your society is much more advanced than we are. * I underestimate how much of an effect a telescope swarm might have. On top of that, if you decide you can see what's happening. Considering the distances involved, the smallest shake on the telescope would go off Earth. so that your final images would probably be the few good images that happened to showcase Earth. You couldn't really get a "film" if you had that in mind. In the end, if I was your characters, I'd try to launch a series of probes in a hit'n'run : come in, take a clip of what's happening, get out. Repeat until you know what's happening or until the probes don't come back. This might require having an independent launching station/ship between Alpha and Earth. **The challenge of synchronizing a telescope swarm** I have added this section as I think it's the kind of information you want if you go ahead with this. But it's not the biggest problem. I don't really know what kind of performance you can get from a telescope swarm. First of all, why would you want to synchronize telescopes? The main point would be to make them move as one and align them on the same object. Earth is a moving target after all. As a starting point, the Webb telescope will be located at the Lagrangian point ([L2](https://en.wikipedia.org/wiki/Lagrangian_point#L2)), which is 1.5 million km from Earth but relatively close. There is a 5 second delay between Earth and L2, making synchronization impossible without FTL communication ([which may or may not be acceptable for you](https://en.wikipedia.org/wiki/Faster-than-light#FTL_communication_possibility)). This means that you can have a synchronized swarm of telescope in the same area of space, but it's simply impossible to have a swarm spanning the whole solar system. You could, however, collect separate data from multiple point of view in the solar system and reassemble them later. [Answer] Requirement: > > "Build a telescope [...] at Alpha Centauri that could resolve [$1-100~\text{m}$] objects" > > > You are correct in assuming that "the primary obstacle is *something something signal **diffraction***" The way to think about diffraction is something like this. Imagine a wave of light headed towards you. If the wave hits one side of your telescope before the other, then you know that it must have come slightly to the side of where you are pointing. However, if the angle is so small that the difference in between when the wave hits each side of the telescope is less than the wavelength, then you can't tell that one hit before the other. You can only get around this by making your telescope larger to exaggerate the difference. Although the precise number depends on the shape of the telescope, the minimum diameter required can be approximated by: $$ D = \frac{\lambda d}{b} $$ Where $d$ is the distance to the target, and $b$ is the desired resolution. We can plug in some estimates for the quantities, assuming that the distance is from Earth to the Alpha Centauri binary, the resolution is [typical for Earth-observing satellites](http://en.wikipedia.org/wiki/Landsat_7), and a wavelength in the middle of the visible spectrum: $$ \begin{align} D &= \frac{500~\text{nm}\times 4.3~\text{ly}}{15~\text{m}} \\ &= 1.4\cdot 10^6~\text{km} \\ &\approx 0.01~\text{AU} \end{align} $$ The required size scales inversely with the resolution. To get the same $0.5~\text{km}$ resolution as a [next-generation geostationary imaging satellite](http://www.goes-r.gov/spacesegment/abi.html) the required size is only $42\,000~\text{km}$; but to acheive the $30~\text{cm}$ resolution of modern satellites the required size balloons up to $0.46~\text{AU}$. Atmospheric turbulence (*seeing* in astronomical parlance) is not an issue here. As usual, Randall [does a good job of explaining this](https://what-if.xkcd.com/32/). So to detect human-size targets you would need a telescope the size of Venus's orbit constructed around one of the stars, and to detect an aircraft carrier you'd need a telescope just slightly larger than the Earth. --- A solid (a.k.a. monolithic) mirror this size would be impossible. Even a segmented mirror (like [JWST will use](http://jwst.nasa.gov/mirrors.html)) would require too much material to be practical. However, in our wave analogy we only ever looked at the two edges of the telescope, not at anything in the middle. It turns out that the middle of the telescope doesn't actually contribute to the maximum resolution, so we can discard it. In fact, we can discard almost all of the mirror, since we don't need every point along the edge either. This is the concept of a [sparse aperture](http://web.mit.edu/deweck/www/PDF_archive/3%20Refereed%20Conference/3_12_SPIE_4849_25.pdf) telescope, the leading theoretical design for massive spaceborne telescopes like the one you want to construct. [This paper](http://arcl.ae.illinois.edu/SFFMT_Chung_Hadaegh_Final.pdf) (coincidentally by one of my professors!) goes over the performance analysis of telescopes constructed of swarms of small mirrors. As for the control of such a swarm, you have two options: * If all of the mirrors know where they are, where the target is, and where the focal point is, they can all align themselves individually, without referencing the others. In this case, to target the mirror I would keep the optical axis of the system locked onto the Sun, and simply steer the detector to follow your target on Earth. Although the velocity of the Earth in its orbit is high (around $30~\text{km}/\text{s}$), 1) it will correspond to a much lower velocity in the focal plane of the telescope, and 2) the speed is pretty constant, so no matter how fast the sensor has to move it can simply coast along. * Alternatively, you could take a cue from [synthetic aperture radar](http://en.wikipedia.org/wiki/Synthetic_aperture_radar) and just record the incoming light pattern, and correct for any misalignment when you do your data processing. This way you only need a precise measurement system, much cheaper per unit than a precision maneuvering system. (Remember, *precision* in this context means nanometer accuracy.) Traditional SAR uses radio waves, which are slow enough that their instantaneous intensity can be recorded. Light has too high a frequency for this to work, so you'd probably instead use some sort of holographic method to record the phase of the incoming light relative to some reference beam. 'Steering' the array would be a data-processing operation; in effect, you'd be taking a petapixel image of the entire solar system. --- In terms of technology, such as system is not too far off. I interned under someone who was interested in these systems, and he helped put together this [technology roadmap](http://hires.gsfc.nasa.gov/si/documents/Carpenter_tech_WP_EOS_032409_v3.pdf), which estimates large-scale swarm telescopes are only 20-50 years away. Such a telescope would certainly be cheaper, in terms of energy and materials, than travel to another star in human timescales (based on current understanding of physics). I would say **go for it!** --- One last thing to mention. You can get more data more cheaply by increasing your spectral resolution instead of your spatial resolution. That is, instead of only processing three spectral bands (red, green, and blue), you shoud record and process a couple dozen bands spread through the infrared, visible, and ultraviolet spectra. This would allow you to determine lots of interesting properties (like surface material and temperature) at every pixel in the image, and is useful for distinguishing similar-looking objects (like snow/ice/clouds/white roofs). [Answer] You might be able to do some interesting things with a swarm of satellites a few thousand AU out, using the local star as a gravitational lens. This is a long way out, but not as far as going all the way back to Sol. A mission called [FOCAL](https://en.wikipedia.org/wiki/FOCAL_(spacecraft)) has been proposed that would send a single telescope out to the Sun's gravitational focus. There's been various discussion about how good the image produced from such a mission would be, see for example Geoffrey A. Landis "[Mission to the Gravitational Focus of the Sun: A Critical Analysis](https://arxiv.org/abs/1604.06351)". Unfortunately Alpha Centauri is a binary star which would likely complicate things. Maybe they could use Proxima as the lens instead. ]
[Question] [ OK, so humanity is going to space, and they are going to take farm animals into space, not only humans on earth value meat, but humans in space do, too. However, they don't want to waste precious resources such as artificial gravity for the farming, so instead of adapting the space ship, they decide to adapt the animals through genetic engineering back on Earth. Fortunately not only has space technology progressed, but genetic engineering has also, so that implementing any change in animals is no problem. This of course poses one important question: What changes should be done to an animal's genes in order to adapt farm animals to weightlessness? [Answer] Animals in zero G experience the same problems humans do in that environment: loss of muscle mass and decrease of bone density. Astronauts run bungee-corded on a special treadmill to minimize these effects. I think it's highly unlikely you're going to get bessie on that treadmill... Honestly, if you're capable of genetic engineering a macro-organism like that, you would find lab grown protein to be far more compact and economical a food source - cultivated beef. It already exists, but it's experimental prohibitively expensive at the moment (hundreds of dollars a pound). That's far more doable in your future society where humanity as a whole is travelling into space. Or you could just use spherical chickens in a vacuum... :D [Answer] I can think of 3 areas for improvement. 1) As has been already mentioned, the control of muscle mass needs to be addressed, so that in a microgravity environment you get muscle rather than fat. Some sort of control of bone density is probably a good idea, too. Presumably the first generation of flight animals has to be raised in a non-zero-gravity environment, so there has to be some sort of internal switch or complementary regulatory pathway for the animal to function in both environments. 2) Assuming we're not talking monkeys or apes, a certain amount of forepaw dexterity needs to be introduced. After all, food won't just sit around waiting to be eaten - the animal will need to be able to hold it. 3) Really, really important - poop modification. It's hard to imagine an animal that can be vacuum-toilet trained. Something like rabbit pellets would be a really good idea, and I don't know what you'll do about urine. Birds, as they don't really have urine, might be a good idea. ETA: And I'll make that 4) efficiency. Meat production is wildly inefficient in terms of resources. I don't have a reference, but my memory suggests that, as a rule of thumb, production of a calorie of meat takes land that would otherwise have produced 10 calories of vegetable foods. This means that, for instance, if your astronauts want 1/3 of their calories as meat, they need 4 times as much hydroponics capacity as they would if they went vegetarian. The increased volume and mass associated with this bigger farm area might well be a problem. So you'd want to engineer for quite extraordinary metabolic efficiency, as well as the other things. [Answer] ![earthworm](https://i.stack.imgur.com/vIb5j.jpg) You might try eating earthworms: 1. They are usefull for agriculture. 2. They have proteins. 3. They can be processed into burgers and nuggets. 4. They wont suffer much from lack of gravity. [Properly prepared eathworms...](http://www.seattlepi.com/lifestyle/article/Properly-prepared-worms-can-be-a-tasty-source-of-1212251.php) [Answer] **We'd be eating more beef than chicken.** If our morality doesn't change regarding the treatment of animals meant for consumption, many animals won't be too difficult to bring into space for farming. We can hook up tubes to the requisite orifices, inject them with [myostatin](https://en.wikipedia.org/wiki/Myostatin#Double_muscled_cattle), and simply let them turn ten energy units of food into one energy unit of meat. **Except chickens.** [Chickens lack the ability to *swallow*](https://en.wikipedia.org/wiki/Swallowing#In_non-mammal_animals), at least, not like we do. We mammals use [peristaltic-wave contractions](http://www.britannica.com/EBchecked/topic/452053/peristalsis) to swallow food and water. Chickens, and most other birds, eat foods and drink water by letting it fall down their throats. They would die of thirst or hunger in a zero gravity environment. However, we could simply get everything they need into them via IV. Or just [cut the heads off](https://en.wikipedia.org/wiki/Mike_the_Headless_Chicken) and stick a tube in there to pump directly to the stomach. Yes, you could do this without removing the head, but you're not going to eat it anyway, why supply it with nutrients? [Answer] If you possessed this sort of genetic engineering technology, you probably wouldn't bother. You'd just grow the meat in vats instead. It'd be a lot more space- and resource-efficient, and with sufficient development of the technology, it'd likely be indistinguishable from the meat produced by real animals. ]
[Question] [ **If mankind in ~ 1000 years would still use chemical propellants for handheld weapons and their ammunition, how would they improve, given the following:** * There has been no dark age, but constant research. * Energy weapons exist, but they are not as effective / too big/heavy to be hauled around by people. * The guns can not use advanced AI, which means target assist would be ok, but not a chip for instance, which detects all enemies around you (able to distinguish friend/foe) and shoots them automatically. [Answer] Some suggestions: **Caseless ammunition** Caseless ammunition works and is lighter and more compact, the difference does not justify breaking compatibility with your existing ammunition types, but with a 1000 years of changing standards... Why not? **Explosive ammunition** Banned by convention and not really necessary against unarmored humans it is much more effective at getting energy to the target. Shaped charge ammunition works for enemies with heavy armor. Armor piercing explosive ammunition is lethal against targets with lighter armor. Shrapnel might replace shotguns against unarmored targets. Electroshock ammunition that uses piezoelectric effect to convert the bullet impact into high voltage electric shock might be available for non-lethal use. Low penetration shrapnel with pellets coated with chemical or biological agents might be an alternative. Most likely people would use some entirely separate system for non-lethal use. **Assisted aim** A range finder and a simple ballistic computer can adjust aim to match range and allow use of heavier ammunition in hand-held weapons. This is because the computer can help retain accuracy while the muzzle velocity is reduced. The computer would also calculate burst timing for shrapnel allowing a shotgun effect at relatively high range. **Situational safety** With slightly improved sensors the weapon might be able to recognize when you are trying to shoot a target with friendly transponder, empty space, a wall, the ground, the sun or moon. It might be able to recognize its current location and compare it to a stored map of areas containing hazardous materials or critical equipment. You can reasonably expect all licensed weapons to be able to recognize police and military transponders. Maybe even government buildings. There might be an international treaty that requires all manufactured civilian weapons to fail to shoot at police transponders. **Authentication** If the police and military have transponders and the guns can recognize it to prevent friendly fire, there is no reason why police or military weapons should fire without a detecting a transponder with the proper type within reach. Weapons could store any relevant data every time the gun is fired and automatically forward it to the relevant authorities. Most likely this would happen when the gun is returned to storage, but in urban areas this could happen immediately and allow the police to be automatically notified of any gunfights using licensed weapons within their jurisdiction. **Scopes** If the gun has sensors the sensor data can be shown on any display. This allows aiming the gun to more flexible with proper accessories. And even at default it might give superior low-light and long distance operation. **Evolutionary** Guns would have evolutionary improvements to recoil, flash, and noise suppression. In thousand years these unspecified improvements might have a noticeable effect. All the described technology would also be extremely mature and reliable by this time. **Note** These are general food for thought suggestions that skip lots of detail that I think is better left to the world builder. For example, I am skipping the civilian and political side of things as it depends of the political situation. Also skipping details of the security of the transponders and other "the devil is in the details" issues. [Answer] **Gauss Guns** Rather than using chemical propulsion, as battery technology improves projectiles might be accelerated using electro-magnetism. One obvious benefit is simpler ammunition. Its just metal slugs. No cases, no propellant, no primers, no grime build-up on the weapon. If you look on YouTube, you can already see videos of hobbyist-built functional - though perhaps not military grade - gauss guns. Rail Guns might also be in use. I don't know if they can be made small enough to be man portable, but they are very feasible as heavier weapons that might be mounted on vehicles or eventually tri-pods. The US Navy already has one deployed for trial purposes. Rail guns also use electricity, but they pass the current through the projectile, which causes the projectile to accelerate down a pair of rails. [Answer] Every round, once fired would function as a tracker and a surveillance device with audio, video and health-monitoring inputs. Telemetry and surveillance feeds would be collected in the bullet's memory and broadcast by radio using encrypted packets, every few seconds. This would be useful not only to confirm that your target is dead, but might also gather useful logistic and strategic information when his body is found and recovered by your enemy. Each round would also carry a very small explosive charge, not enough to do much additional damage and not set to explode on contact. Rather, the charge would lay dormant whereever the bullet lodged itself until a digital radio signal from the rifle set it off. More of a ground tactics tool than a weapon, this on-call noise maker could provide just the right level of distraction during a prowling/hunter-prey scenario. Simultaneously, rounds could be made durable. Using as of yet unknown metal handling techniques, bullets could be made so tough that they don't deform when fired. The advantage to having indestructable ammo is that it is reusable. After an area has been secured, use each bullet's integrated tracker to find it. Attach a new cartridge or non-cartridged propellant insert to each bullet, and put it back in the gun. The gun would then run some diagnostics on the bullet, check for unlikely but still possible deformation and then, if acceptable, return it to its inventory. Reusuable ammo would not always be a major asset, but in some long-term/low-supplied scenarios, it would be vital. ---edited to add one more ammo feature--- Brakes! Every round could be set to only travel a specified distance before deploying fins which stop spin and create bullet slowing drag. Then, in the microsecond after the bullet has stopped spinning, the top most fins bend all the way back, removing their drag effect and causing the bullet to change course and slam into the ground. The gun would give each round a maximum range as it is fired, allowing for a variety of curved trajectory uses such as firing over a intervening obstacle and having the bullets slam down into the people standing right behind it. [Answer] To complement to VilleNiemi's answer, I'll throw some ideas on gun and cybernetics. Those ideas only really work for active users like soldiers or police officers. They assume that the user is equipped with a special helmet or has cybernetic implants. That equipment could also be part of the weapon package sold to a civilian. You might want to look at the military rifles from John Scalzi's Old man's war, most of those ideas are inspired by them. Those guns are basically telepathically controlled (from cybernetic technology), the owner must submit an electronic confirmation to shoot or input any command. They have no AI to speak off, but the weapon is completely computer controlled. **Authentication :** This is something Ville already covered. So I will only add that, if cybernetics are in your world, they would be used for that and possibly to access other function. **Automatic monitoring** The gun can monitor how many ammunition are left and signal problems as they happen. Depending on the level of electronic technology available, they could be sent directly in the user's vision. Sent to a portable screen similar to google glasses. Or displayed on the gun itself. **Scope sight** If the communication and camera technology are advanced enough, the scope's image could be sent directly to the shooter's view. Like before, how it is seen depends on the level of cybernetics available. **Multiple ammunition types** If the gun is computerized, it can have more than one firing system or ammunition mechanism. For example, a military rifle could carry both standard rounds for soldiers and explosive rounds for armored targets. A rotating part similar to a revolver's barrel allows switching between them. The command could be a switch on the weapon or a mental command. This would surely quickly increase the weight of the weapon. **About computerized guns.** It might also be a good idea to take a loot at how mobile devices are developing. As more and more electronics are packed around a weapon, I could see the same kind of evolution happening in a much more focussed and utilitarian way. Here's a few ideas I have off the top of my head : **Synchronised weapons** A squad's guns synchronise so that only 1 person is controlling the firing of all of them. I could see each person having to pull the trigger to allow his gun to fire, but all weapons would only fire when the leader orders it. I am not quite sure how this could be applied in a realistic setting. As the only way I see such a level of synchronisation being needed is for the opening volley against highly armored targets. Or against automated defences. These really depends on your world. This application would probably be limited to military settings. **Shared view** This is moving slightly away from the weapon themselves. But if the scope is sent to the officer's view directly, the same could be done to another officer's view. This could be used to show a target and to make sure everyone is ready to fire. [Answer] Vernor Vinge's Peace War novel had smart guns with some cool features. In the story a character who doesn't know much about guns at all and isn't a good shot takes out a bunch of the enemy. He does it by holding down the trigger and waving the gun across the fight. This works because the gun was computer controlled fully automatic. It sensed the targets coming under the sight, programmed the target data into the round and fired. Each round had the ability to track the target and guide itself. I definitely see that being doable. Eye tracking and targeting. Very popular in cyberpunk novels and I can see this working easily. In fact, TrackingPoint is already nearly there. So you'd be wearing your Google Glass, or far more advanced contact lens version. It would have a Bluetooth link to the gun. It would show your gun's current bullet path in one mode. In the other the gun would aim itself at your eye's position, via servo motors on the barrel or using bullet guidance. The servo motors will also be used to provide full stabilization. Just like the main gun on the Abrams tank. Firing accurately while running will be a thing. Making incredible sniper shots will also be something anyone can do. The range limitation will become based on line of sight and bullet velocity and stability. Breathing, heartbeat and hand jitter will be a thing of the past. In 1,000 years I expect a lot of humans living in space. There would be a need for zero-G fighting. Many guns would include recoil cancellation using various techniques so that their user does not go flying around while shooting. Gun scopes may include orbital dynamics modes so that you don't miss while shooting at a target 10km away, and also so you don't shoot known satellites or even yourself 90 minutes later. The gun might also track all projectiles fired during the fight for later cleanup and avoidance. A gunfight in orbit could still be killing people years later otherwise. ]
[Question] [ If a human is kidnapped by an alien vessel and taken to another planet - and, for the sake of argument, let's assume that the alien life-form lives in a completely different environment from Earth's. Assuming, of course, that this alien race is far more technologically advanced than us, is it technically possible for the human to be "changed" in a way that he can breathe the planet's "air" (as opposed to Earth's) without dying? [Answer] To elaborate on bowlturner's answer, oxygen is uniquely suited for providing energy to large life-forms. It's one of the most effective oxidizers on the periodic table, (hence the term) and it can accept two bonds, unlike Fluorine and its friends. Digesting food is the process of burning it in a controlled manner to release the chemical energy, and you usually need some kind of oxidizer to do so. While there is more than one way to accomplish that oxidation, oxygen is so useful that an alien species is hugely likely to evolve the capability to process it, if it is at all present in their environment, even if they aren't carbon based lifeforms. And, too many of our chemical processes rely on it. You would have to artificially recreate a human from the atoms up to make them not use oxygen. Genetics alone can't overcome that hurdle in such a complex organism. That said, as long as there is free oxygen present in the atmosphere, bolt-on adaptations to other toxins in the atmosphere are certainly within the realm of possibility. Alternatively, in a truly oxygen-free atmosphere, if the aliens didn't care too much about disfigurement or risk of explosion, you could have them grow an oxygen tank for your poor subject out of muscle and bone, with an umbilical cord of sorts fused to their nose. [Answer] To start with the human body is designed to run on Oxygen, and it would take a huge change, likely making us something else entirely if we needed to run on a different gas. However, assuming you mean that the atmosphere is poisonous but still has Oxygen in it then it could be possible. Say the CO2 is extremely high, we could be redesigned to filter it out, or not absorb it through the lungs or maybe even have a converter to change the CO2 back to O2. Similar things might be done if other gases such as Chlorine were in the atmosphere at dangerous quantities, but special breathing apparatus could be used too, though not quite as useful since you still need to remove it to eat etc. [Answer] Actually, even a non-genetically modified human can already breathe quite a range of gases beyond a simple Oxygen/Nitrogen mix. There are numerous [breathing gases](http://en.wikipedia.org/wiki/Breathing_gas) that are in use, in a wide array of applications such as sea diving, mountain climbing, hyperbaric chambers, and spacecraft. The main requirements are: the correct amount of oxygen (within a certain range), and a lack of toxicity. Usually, breathing gases will contain oxygen, and some form of inert gas or gasses, such as Nitrogen, Hydrogen, Helium, Neon, or Argon. Even pure oxygen can be used. However, not all of these gases are useful for deep sea diving, because some (like pure oxygen, argon, or nitrogen) will become more toxic under higher pressures. Oxygen is necessary, however, for practically every reaction that occurs in the human body, but especially by the brain. If there is not enough oxygen, the brain will suffer [Hypoxia](http://en.wikipedia.org/wiki/Cerebral_hypoxia). Initially, this will cause a sense of euphoria, and an inability to perform complex tasks, shortly followed by passing out, permanent brain damage, and eventually death. Compared to the brain, the rest of the body is relatively tolerant of lower oxygen levels, at least for a little while. But it's still a critical factor for life. On the other hand, if the body cannot eliminate enough CO2 (perhaps because the atmosphere already contains a high concentration of it, or is too dense to fully exhale), then the CO2 will form carbonic acid in the blood. This causes [Acidosis](http://en.wikipedia.org/wiki/Acidosis), where the blood becomes too acidic, and can lead from headaches, to sleepiness, to causing cellular damage, to a coma, and probably death. If you want your human to survive in a low-oxygen environment, there's not really an easy way around this, short of a breathing apparatus. Someone mentioned the possibility of a biological rebreather. I'm not sure if that could actually work, but it's one semi-plausible solution. Or instead, you might find a way to slow his entire body metabolism down, and put him in a state of hibernation or cryostasis, but he won't be conscious. You could perhaps replace his brain with a miniaturized computer, but then instead of oxygen, you need power. And if you can upload his mind into a computer, why keep the rest of the body? **Addendum**: To show how forgiving the human respiratory system can be, as long as it gets enough O2 and gets rid of CO2, there have been some partially-successful experiments that demonstrate the possibility of [breathing an oxygenated liquid](http://gizmodo.com/can-humans-breathe-liquid-1156138301). This mode of breathing has been postulated in science fiction for deep-sea divers, or astronauts in high-acceleration spacecraft. [Answer] Something else to keep in mind here: When you look at the possible chemical paths that support life things are quite limited. Looking at worlds with Earthlike temperatures there's only one viable pattern--carbon for the molecular backbone, oxygen as an oxidizer. Thus while the alien world might have toxins that need filtering out it's going to have the oxygen. The standard sci-fi chlorine and fluorine based life simply doesn't work--both of these atoms are far less abundant than oxygen due to being less stable on a nuclear level and also created by far less common reaction sequences. Chlorine and fluorine both react with oxygen--for a world to have free chlorine or fluorine in atmosphere all the oxygen must have reacted with it and likewise it must have taken oxygen's place in the rocks. Most rocks are mostly silicon and oxygen. Thus you need an incredible amount of them and you're simply not going to find it. There's nothing else left to be an oxidizer, your aliens breathe oxygen. [Answer] Whilst your body is evolved to use oxygen its evolved to use it in quite a narrow concentration band. Too little and you pass out, suffer brain damage and die, too much and your nervous system is basically "oxidized" away and the resulting damage can be fatal. We need oxygen but we need the right amounts. [Answer] A person could normally have a space suit, we would make out of machery as an independent exoshell. An advanced alien might make an adaptor out of *living* material and integrate it with our body, so it can transmit senses of touch etc and is self-maintaining and repairing taking material and energy from our blood. But it provides a rebreather to fit around the lung which still exchanges oxygen and carbon diodide, and provides a food processing system that transfers needed material to its own systems and produces compatible sludge to drop into the human intestine. An analysis would notice a human body with a lung and stomoch removed and forign organs added and plumbed in; the skin removed and replaced with something that tolerates the outside environment; the eyes covered or replaced; the various openings sealed and plumbed into the support equipment instead. Look at Fred Pohl's *Man Plus* for an example of adapting a human to live on Mars. ]
[Question] [ In many a sci-fi, the villains (and sometimes the good guys) have glowing lenses attached to their gas masks to help both identify them and provide a useful target for the protagonists. The obvious reason any (kinda) moderately sane military would do this was stated before hand, identification. However, I feel that it is far too obvious of a identifier since the enemy would also know where you are. Intimidation? Sure, but looks aren't stopping a bullet from spewing your brains out once people adjust to the look, especially if they're professional soldiers. One other possibility is that they are infrared lights for inbuilt cameras to detect. The issue is that infrared is normally invisible and doesn't require such large lens in the first place. Just a single infrared LED would do. So with all this in mind, **why would militaries have glowing lenses for their troops?** Notes: * Need to be visible to regular people Similar to this: [![A soldier searibg a gas mask with glowing eyes](https://i.stack.imgur.com/8Vojo.jpg)](https://i.stack.imgur.com/8Vojo.jpg) [Answer] # Because stealth doesn't work In this sci fi world, advanced scanning technology makes stealth infeasible for the average trooper. Perhaps very advanced special troopers can do it, but not your average grunt. Heat scanning and computer analysis means you can't hide. It makes more sense to openly advertise your presence to avoid friendly fire incidents and enable coordination, so most soldiers have colour coded eyes. [Answer] High visibility battle-dress predominated across most militaries for most of history up to the 20th century. Duplicate the conditions: the last few times the military fought a major conflict, the killing power *against* that enemy of a small group of infantry in enfilade was small; and the enemy was not able to effectively engage point targets at distances much greater than the distance at which any infantryman, however clothed, was easily spotted *by* that enemy. For example: maybe their last few generations of war were against Starship Troopers bugs, or they have Dune shields that block all fast projectiles. [Answer] **They already had a bunch for rescue / salvage work.** [![helmet with light](https://i.stack.imgur.com/Z8hF1.png)](https://i.stack.imgur.com/Z8hF1.png) [https://www.amazon.com/Futt-Outdoor-Emergency-Goggles-Flashlight/dp/B07PJF6SMQ](https://rads.stackoverflow.com/amzn/click/com/B07PJF6SMQ) Really it makes sense to have your hands free if you are doing stuff in the dark. Lights on goggles are just as good as lights stuck on the side of your head! And if what you are doing is trying to find people you are unlikely to be shot because the people see you. They will yell to bring you over when they see you. And these are fine strong helmets and the lit goggles all have fresh batteries in them. They have hardly been used! What, we should buy a bunch of new stuff because people don't like the lit goggles? You don't like them, then turn them off. Oh, you left them turned on, did you? It is because you like them, isn't it. You can admit it. They are pretty sweet. The rescue folks thought so too. [Answer] ## It's a visor helmet The aliens use a light-weight interferometric sensor technique to enhance the contrast of their eye sight. For example they can see where you look at, from 500 meters away. The only disadvantage of this enhancement is that the device requires a second light source, which is quite bright and visible. They take that drawback for granted, the advantage of having 140+ eyesight day and night is much more valuable than the disadvantage of visibility. They'll see you first, anyway.. ]
[Question] [ In waterworlds where people live mostly under water or have access to bodies of water how is violence perpetuated in close quarters? Projectiles lose their power really fast making them unviable. Bladed weapons are also slow. Explosives tend to hurt person deploying them as well. Grappling could be an option, but people tend to want an advantage, not equal fight. How do you (gun)fight underwater? [Answer] Close quarters violence underwater wouldn't be impacted as much as you might think. There are four areas I can think of where they would be adjusted. In general, they are effected by two factors: water resists movement, and shorter range means it's harder to put an AoE attack far enough that it doesn't hurt you. ## Hand to hand Heavy swung weapons like hammers and halberds wouldn't be effective because they would lose too much energy. Blunt trauma weapons like clubs or morning stars wouldn't exist. The most efficient melee weapons would be spears and knives. You could do some sword-like things, but they would be mostly ineffective against armor. Aerodynamics would be a huge factor, changing the shape of anything swung to have the lowest amount of drag, and it would take more skill to hold the weapon at the right angle. It occurs to me that you could have a axe-like weapon with a thin profile, but for which the wielder purposely turned the weapon in mid-flight to change its trajectory. Again, you'd want the Myth Busters to actually test the effectiveness of such a thing, and it's doubtful that it would be more effective than a spear. ## Fire arms This is the land of spear guns. There are numerous implementations of pistols and rifles that can get significant range under water. By "significant" I mean "pathetic by air standards." The equivalent of a sniper rifle has an accurate range out to around 60 meters, and your typical rifle will have half that. The trick is that you use long, pointy projectiles. Darts, really. And then put a larger explosive charge behind it. You can extend the range by giving the bullet a flat or concave nose, which creates a tube of vacuum, eliminating drag along the edges of the bullet. Even then, a bullet will continue moving until it displaces its mass x velocity in water, which makes it a mass-to-cross section formula. By putting more mass behind a smaller cross section, you get significant range improvements. The underwater equivalent to a gyro-jet wouldn't have adequate accuracy, as small water currents would throw it off. It would be like trying for a long golf putt. Theoretically, you could have a gun that sets off a shaped charge, concussing everything in a cone in front of it. I don't think I'd be willing to test such a weapon, though. ## Explosives The concussive force of an explosive is, in fact, conveyed more efficiently by water. It's almost impossible to throw a normal grenade far enough to not injure yourself. Thus, we don't use normal grenades. Instead, we use tiny torpedos. Throwing one of these things like a javelin activates its propeller to send it swimming forth towards the enemy. When the propeller runs out, it explodes. This is an area where the gyro-jet weapon could be useful. Basically, a tiny rocket-propelled grenade launcher. I'm sure this could be scaled up for anti-armor activities. ## Weird stuff The problem with a super-cavitation weapon like the pistol shrimp uses is that, for less energy, you can fire a projectile. The shrimp only does that because it can't grow its own bullets. This *could* be the basis of a stunning melee weapon, where you poke it at an enemy and pull a trigger, releasing an elastically retracted clapper. Flame throwers are a non-starter, but you could try sodium/phosphorus rounds. Gas attacks, like tear gas (tear fluid, in this case), would have effectiveness based on the wet-suit tech used by the combatants. You could launch serious skin irritants into the water, but the shorter range would mean that it would be harder to limit the area of effect to just your enemies. Acoustic grenades would come into their own. Something that vibrated the water in such a way that it irritated ear drums in the vicinity would be pretty easy to engineer. [Answer] [Harpoon guns are a thing](https://tvtropes.org/pmwiki/pmwiki.php/Main/HarpoonGun): > > In reality, hand-held harpoon guns used by divers generally use elastic cords to propel harpoons over fairly short distances to spear fish, a bit like an underwater crossbow. However, some firearms designed for underwater use are basically miniature harpoon guns, throwing slim darts — normal guns simply won't work for anything further than point-blank range underwater, if at all. (Not that darts carrying much further, but they can be optimised for the job.) > > > And here you have [a list of real life underwater firearms](https://en.wikipedia.org/wiki/Underwater_firearm), such as the [Heckler & Koch P11](https://en.wikipedia.org/wiki/Heckler_%26_Koch_P11). [![The Heckler & Koch P11 pistol, an underwater fiream](https://i.stack.imgur.com/y1TaO.jpg)](https://i.stack.imgur.com/y1TaO.jpg) [Answer] > > Explosives tend to hurt person deploying them as well > > > only if there is nothing containing and directing the blast. Look at our world: an exploding grenade hurts everybody around it, however whoever uses a rifle has an explosion happening next to their cheek without getting hurt. If you can direct the pressure wave, you can hurt without getting hurt. It's the same principle of [lithotripsy](https://en.wikipedia.org/wiki/Lithotripsy) > > In extracorporeal shock wave lithotripsy (ESWL), external shockwaves are focused at the stone to pulverize it. [...] Electrohydraulic lithotripsy is an industrial technique for fragmenting rocks by using electrodes to create shockwaves. It was applied to bile duct stones in 1975. It can damage tissue and is mostly used in biliary tract specialty centers. Pneumatic mechanical devices have been used with endoscopes, commonly for large and hard stones. > > > [Answer] **Use animals** I don't know the tameability/trainability of the local aquafauna of your world/s but you could use marine life to deal damage to your enemy. Even if you only have access to relatively mindless/voracious predators you can feed them just enough to keep them alive/fit but not enough to sate their hunger, leading to them seeking out and attacking other living things once released. Of course, you'll need to take measures to make sure they don't go after you as well, but the use of animals for warfare is not an entirely new concept as history teaches us. [Answer] # By using an SRBB Gun (Solid Rocket Booster Bullet) Basically, the gun doesn’t provide the propulsion, the bullet does. All the “gun” does is trigger the Solid Rocket Booster to fire. Then the SRBB has a burn time of X (insert time here based on caliber of “bullet” for your world) before it runs out of solid fuel and de-accelerates the ammunition. [Answer] Why not use the water itself as a weapon, like the pistol shrimp, which claw snap can create a shockwave that can stun or kill it's prey/ennemy. [Answer] Just have weapons along the line of a torpedo. Since it's in water a good idea would be to have delayed explosion on a torpedo like missile. Shoot it in their vicinity and either blow it up remotely or have it on a timer. ]
[Question] [ I have a mountain range that separates two places that certain people will want to go between fairly regularly. Right now they have to travel around or over a mountain range to do that. I've been thinking about ideas of how to make traversal easier and quicker and one possibility that occurred to me was a cave(rn) system that could be entered on one side and eventually exited through the opposite side, similar to what Tolkien did with the Mines of Moria. The difference here, however, is that Moria was excavated while I'm supposing this to be a natural formation. I don't know enough about geology to say whether or not this is absurd. [Answer] This is definitely possible, but often such systems are not so easy to walk in and out. Please take a look at this cave in Abkhazia: <https://inis.iaea.org/search/search.aspx?orig_q=RN:47073167> It has four known entrances on different heights, distance between them is several kilometers: <http://www.rgo-speleo.ru/caves/hipsta/sneg_p_sm08.gif> . Take a look at its entrance: <https://v-georgia.com/wp-content/uploads/2015/06/0_eeecc_30312dba_orig.jpg> – not an easy path, right? There is also a smaller cave that has entrance and exit, that is available to the general public to visit: <https://web.archive.org/web/20180106103509/http://www.abhaztur.com/upload/files/peshhera_2.jpg> but it is not as long, probably less than a kilometer. [Answer] **IMO It's improbable, but not impossible** Caves are formed for a variety of reasons, but the most common is erosion. So, is it possible to have a mountain made otherwise of basalt or bedrock to have a seam of sedimentary rock running through it that could be eroded into a mountain-traversing cave system? Sure. There are no examples on Earth that I know of, but I can't see a reason why it's impossible. Please note that such a condition would be naturally unstable. The seam would represent a weakness in the structure of a very heavy mountain. Add any kind of seismic events and that weakness would cause the cave to collapse. But that's good for your story, isn't it? It means the cave system isn't entirely safe, and that's always good for drama! ]
[Question] [ In a story idea I have, there is a massive, stationary beast, with teeth the size of houses, a body as large as a continent, and an unfathomably large mouth (don't ask how it sustains itself, nobody knows or cares) Common sense dictates that humans would avoid this thing at all costs. And yet, there are humans living INSIDE this thing's mouth. Enough to form a sizeable settlement, in fact. It would likely strike an outside observer as utterly insane; after all, living in some massive beastie's mouth is the very definition of living dangerously, as there is always the risk of being swallowed and digested looming over you. Plus, spending your life inside a wet, warm mouth seems rather unappealing. All this raises the question: **Why would these humans be living in the mouth of this thing?!** [Answer] > > Common sense dictates that humans would avoid this thing at all costs. > > > Humans build houses and settlements on the side of active volcanoes, on shores subjected to tsunami or flooding, in territories subject to earthquakes or plagued by endemic illnesses or other risks. There is no absolute scale, every decision on where to settle is based on a trade off. Unless the creature chews every 5 minutes, it's possible that some people will decide that settling in the mouth is worth the effort and the risk. It can be that this creature, while eating, gets food remains between its teeth, these remains be valuable ores, or that its mouth secrets something valuable for the humans, which harvest and sell it for a profit. [Answer] If these humans are in a situation where the life outside of the creature's mouth is even worse, then it makes complete sense for them to live like this. It sounds like there are some advantages to this setup. Humans living inside are protected from weather extremes and from any dangerous predators. If they can't grow/hunt their own food then it's a problem. Then again, this creature must consume such a gigantic amount of food that feeding off of bits of food stuck between the teeth could provide all the food this settlement needs. Lack of building/crafting materials could also be a problem but this creature probably swallows entire trees and rocks accidentally. Actually this sounds like this could be a symbiotic relationship. The human settlement strips out bits of food that could be hard for the creature to digest and uses it for building/crafting and in return they get safety and a steady supply of food. Lack of sunlight and fresh air would still be a problem, but again depending on what life is like outside this could still be preferable for these people. [Answer] # Mouth? No. It's a cave, right? Your creature doesn't move, doesn't obviously consume food, and if it gets water, it's because it siphons off of a river (which might constitute a food source...). Something this passive doesn't have much active metabolism, so are the settlers really so sure this thing is alive? Maybe they think it's a cave. Maybe it is a ridiculously huge corpse. Either way, there isn't much danger. Maybe this is a giant fungus, or plant, or sponge-like creature, and calling this chasm a mouth sounds ridiculous since it doesn't obviously eat. It might, for all intents and purposes be a giant nook in a tree. People live in trees when it suits them. Any advantage of living there (shelter, nutrients, security, warmth, etc.) would be enough to make the creature's mouth desirable. If you don't believe the thing is alive, or that it's completely immobilized and harmless, then WHY NOT? [Answer] Think valuables and resources. Remember, [ambergris](https://en.wikipedia.org/wiki/Ambergris) is a valuable perfume additive that is formed in the digestive tract of sperm whales, and [kopi luwak](https://en.wikipedia.org/wiki/Kopi_luwak) is an expensive coffee bean that must be partially digested and excreted by civets. Perhaps something this creature produces, secretes, excretes, regurgitates, etc has human use: strong and light organic construction materials, medicines or intoxicants, unique crystals mined from its teeth for jewelry or technology, etc, etc. People will live just about anywhere if living there gives them a killing in the market. [Answer] **Rain:** These people like to stay dry. The height of the cave must be at least several miles high. A settlement inside the mouth would be protected from bad weather while still getting enough sunlight to see, unlike a traditional cave where the opening is too shallow for significant light to pass through, not to mention far too small for a settlement. If the weather in the region is particularly severe, perhaps this is the only place that poor people, who can't afford sturdier stone homes, can build their shacks. **Heat:** The creature might be maintaining an internal body temp of some temperature, perhaps a reasonable hibernating 60 degrees. The body temp of the beast prevents winter temperatures from occurring within its body-- it's always t-shirt weather in the body of the beast! I would live in the place where I don't freeze to death in the winter. **Food?** If the creature is an animal and edible, maybe it's a free supply of fresh meat for these settlers. Come dinner time, they head outside with a carving knife and collect dinner. [Answer] Well isn't this interesting. The "why" of the question reminds me of the iconic response from Alastor of "Hazbin Hotel" to being asked "why does anyone do anything?": *sheer, absolute boredom!* Obviously no one would decide to live inside some gargantuan creature's mouth just for the kick of it, but jokes aside: In a fantasy setting there could be a ton of different reasons for why people would go on creating a similar dwelling. I was thinking of something like this - this thing is the size of a continent you said. Well, what if the people residing there were being hunted or threatened by some sort of creatures or civilization from a neighbouring continent and it so happens that said threatening force is deadly afraid of this continent like-creature? I mean, everyone would be. But let's suppose this runaway people took the saying "keep your friends close and your enemies closer" to a whole new level and decided to go live directly inside something that terrifies their adversaries more than anything else? At least they would be sure they wouldn't be attacked anymore. We could also add that this creature lives with his mouth open and like you said, doesn't move. There would be no problem with the oxygen or light. The food depends on what creatures are present in this world and if any of them would go inside the mouth. Another point in favour of living there would be that this beast only attacks/reacts negatively to the presence of specific beings: among them the same ones that threaten the people who decided to go live inside the mouth. This would be perfect: for the majority of the time this thing is immobile, mouth open, maybe it only feeds off of some particles present in the air together with who or whatever happens to tumble down its throat, I don't know. It basically stays in a near constant state of sleep until it senses its enemies coming near. Then it goes berserk and is capable of annihilating anything. If I were part of those people who decided to live there and these were the premises I honestly would think it a good choice. 10/10 would recommend XD. [Answer] **Potion Seller** [![enter image description here](https://i.stack.imgur.com/LnqzZ.png)](https://i.stack.imgur.com/LnqzZ.png) There is not much of a market for potions these days. But if a single adventurer comes by you can make it big selling them 200 red potions and 400 green potions. Adventurers have lots of moolah you see, from slaughtering exotic and endangered fauna. Unfortunately adventurers are few and far between. Fortunately many of the most popular quest routes take you inside the beast and out through the other end. Often they are searching for rare ingredients that can only be found in the depth of the beast. Or else they are looking for princesses of neighboring kingdoms who so carelessly fell into the pit while out admiring the sunset. Whatever their motives, those guys need potions. And they need them yesterday. And it's a good thing you came to us. [Answer] ## Your humans are just like giant bacterias... We have to remember that mouths are [host to hundreds if not thousands of microspecies](https://en.wikipedia.org/wiki/Oral_microbiology). And, as far as I know, we don't kill all of them just by closing it! In fact, we never reach a clean mouth even after making your toothbrushing. Remember that teeth are sized against a specific prey, you don't have to worry if they're in the ten or hundred of meters. Indeed, the space between them would allow anyone to move in and out freely. You'd need to stand on top of them to risk something (and even then!). ## ... And the immune system doesn't deal well with humans Your humans are smart, your humans are clever, and they are greedy. In fact, among the species that decides to live in the mouth, humans are the ones that are digging holes in the teeth. In toothcare, it's well known that once a carie started to set in, the body is unable to get rid of it, external help is needed. And humans are just the perfect candidate for that : They drill a house and craft dentin solid tools. And... Also precious necklaces to sell out as the "legendary creatinent ivory lucky charms", too. There's nothing to stop 'em poaching there. Moreover, like you often see giant creatures being slower than mice üê≠, your giant creature has a very slow metabolism : Any movement is extremely slow, Breathing is done over weeks (lowering drastically the wind speed), and saliva's flowing like rivers that move over time, leaving sometimes puddles here and there. Nothing you cannot deal with. At most you have to worry about the yearly cough, which takes the shape of a storm for 3 days. And heat is only hitting up if you dig straight down into a blood vessel; There's so much distance to them that most of the heat dissipates before it reaches the surface, leaving only a warm, cozy carpet to lie on. Really, it's a very nice place to live there! Weird sure, but nice! ]
[Question] [ My story takes place on a dark, dusty planet full of canyons and tunnels. The atmosphere is compositionally similar to Earth’s, but it is too dark and cloudy for humans to see properly. The humans colonizing this planet in the far future are at war, so they build their best soldiers advanced combat suits. These include a short-range (150ft max) sound-based detection system. As visibility is limited, and combat occurs in small spaces, the reading from the system is processed by the suit and visually rendered inside the soldier’s visor, allowing them to “see.” While it is less precise than light-based vision, high frequencies and advanced processing allow soldiers to be able to see (and shoot) their enemies. Combatants would use relatively modern firearms in very small, tight spaces. Would this be a feasible scenario? I found [this](https://worldbuilding.stackexchange.com/questions/96879/are-echolocation-rifle-sights-feasible) related question, but figured these suits do not need long-ranged capability, instead needing quick, precise information over a small area. [Answer] Well, bats seems to be perfectly capable of moving into caves without bumping into objects, so echolocation in narrow environments should not be a big problem. The real problem is that to make it work, your soldiers will need to have the suits constantly "shouting", which is the more advanced version of lighting a cigarette in the dark of the night: it will declare the suit position to anybody who has ears to ear. Additional problem, which can be solved or mitigated with some engineering, is that many soldiers in the same environment will end up saturating it with the emissions from their suits. It will be like trying to listen to your friend while being in a loud hall where everybody is talking. [Answer] **Possibly** Keith Morrison and Sean Boddy nailed down the problem in the question you linked. Anyone relying on an active sensor system will have the use of that sensor system detected at a greater range than it will allow them to detect targets. Imagine that you are at one end of a L-shaped tunnel, not shining any lights and not making any noise. If someone at the other end of the tunnel shines a light then they will not see you but the light they are shining will be visible at the bend and you will know they are there. If they speak then the sound will reflect around the corner and you will here them. If they send out a pulse of high frequency sound that their suit can read then your suit can detect it. Passive detection systems are preferable where possible, but passive sonar may be difficult where there is presumably enough constant wind to keep large quantities of dust suspended in the air. (Without the wind the dust will settle and your environment will not be as described.) So if the only alternative is active detection systems then don't have the soldiers emitting the active signals. Instead, deploy a network of tiny mobile sensors and/or drones that emit the echolocation pulses and transmit the battlefield picture to the soldiers in their suits. That way, all the enemy knows when they detect a pulse is that there is a sensor in the area, they don't know whether it is a decoy, forward recon or providing targeting information to a squad of soldiers just around the corner. The same principle applies whether you are using sonar, radar, or any system that relies on emitting a pulse and detecting a return. If sonar echolocation suits the flavour of your world then go for it. (Guessing that the reason you want sonar may be due to the suspended dust of the world interferes with getting returns in much of the EM spectrum, whether by accident or design.) Note that all of this is assuming relatively symmetric warfare. If the humans are fighting against a non-sapient or primitive enemy that cannot detect the source of high frequency sound bursts then the echolocating humans can operate with impunity. [Answer] Yet another frame challenge.. ## **Why not use a thermal imaging camera ?** **Range** With echo location, movement of the soldier can be corrected on the fly, by software, but a range of 150 feet is not spectacular.. Sound based systems have low resolution and they will require controls and a special interactive HUD in the helmet of the soldier. The sound can be detected by the enemy. **Not solid state** For military purposes operating in dusty and dirty environments, a sound based system has the disadvantage of (micro-) moving parts. The sound detector, e.g. a microphone of some kind, can easily get damaged and it would get cluttered with dust particles. It needs to be protected, reducing sensitivity. **The alternative** Our 21th century military and industry are already using infrared cameras.. A good thermal camera can look through smoke and dust. Check out <https://www.infrascan.com.au/blog/can-thermal-imaging-cameras-see-through-these-19-things> [![enter image description here](https://i.stack.imgur.com/CHzZR.png)](https://i.stack.imgur.com/CHzZR.png) <https://www.sensorsinc.com/applications/general/imaging-through-haze> ]
[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/215189/edit). Closed 2 years ago. This post was edited and submitted for review 2 years ago and failed to reopen the post: > > Original close reason(s) were not resolved > > > [Improve this question](/posts/215189/edit) I'm writing a story based on people trapped in a city which has had multiple nuclear bombs set off in it, and so has some very irradiated reason. The people in it have slightly more advanced than modern day earth scientific knowledge so they know about radiation, but lack a reasonable supply chain to build more advanced technology items that function in the city like kevlar suits or computers. They have ample materials and supplies available as would be common in a modern city that got nuked, along with a wide array of common animals around, but don't have a worldwide supply chain to source rare plants and animals from. How would they go into radioactive areas to explore? Their supply situation is unstable, so waiting it out isn't a reasonable location, and radioactive areas often contain valuable supplies or link to key parts of the city, hence why they were nuked. [Existing questions on this matter](https://worldbuilding.stackexchange.com/questions/197365/ways-of-detection-of-radiation-wastelands-spots-in-a-technology-free-world) have mostly focused on radiation being fine and not being an issue, which isn't true here due to widespead recent use of nukes, or on sourcing rare and exotic plants. Ideal answers will help explain the sort of society and adaptions you could take to minimize the risk of going into nuked areas, and won't assume extremely rare supplies or advanced technology. [Answer] Keep the radioactive dust out of your food and water, and *especially* out of the air your breathe. Even a simple wetted-cloth facemask will filter out 99%+ of the bad stuff. Wear gloves, longsleeve clothing, head cover, goggles. Again, the purpose is to make radioactive dust settle on the clothing, which can be discarded, rather than on your skin. At every known safe opportunity, cleanse yourself and your equipment. Avoid the *bad* hot-spots. To detect the bad hotspots, you need a radiation detector. Possible options: * Pilfer a preexisting Geiger counter. They are *way* more common than you might think. Right now, there are at least hundreds and possibly thousands of them in your home city, assuming you live in a large metro. You can get a crappy but functional one from Amazon for $50, so you can imagine just how many households have one "just in case" * Build yourself a gold-leaf electroscope. This uses less-than-medieval tech to make, with the knowledge you could have made one in ancient Sumeria of 4000BC These only detect alpha and beta radiation, and require careful handling to not mechanically reset by accident. * If you are willing to limit your exploration to darker hours, a scintillation detector would work even better. Without electronic amplification these are very dim, but they detect x-ray and gamma rays too. If you absolutely *must* enter high radiation zones, use clothing with lead foil sewn into it. Lead is very easy to form into sheets of arbitrary thickness, is soft enough to be sewn into/onto clothing, and flexible enough to provide full coverage of joints. A 3mm covering over your clothing (weighing 20kg for a large man) will provide the ability to reduce incoming gamma radiation by a factor of 8 and completely block Alpha and Beta rays. A 6mm coating (at a very painful 40kg) will reduce gamma radiation by a factor 64. But really, that air filter is by far the most important item. If you allow radioactive dust to settle in your lungs, there is *no ways* to wash it off. You breathe it in, and it is with you of the rest of your life. (which is not likely to be very long) [Answer] Whenever they go out exploring they would need to wear some full body suit, breathing mask included, to prevent accumulating radioactive dust on themselves. Together with that they should enforce a strong separation between what's worn in the outside (potentially radioactive environment) and what is worn inside (safe environment). If they have a supply of running water, upon reentry they would fully strip down of all the clothes, wash their body and then wear inside clothes, while whatever needs to be carried in from the outside would be at least washed with water to remove as much as possible of the radioactive dust. Then, if checking with a Geiger counter would not trip off an alarm, the item and the person would be allowed inside. The outside clothes would be probably washed and reused. For filtering the air, I guess that a centrifugal filter, muscle powered, can be the most simple solution, lacking anything else more complex. Again the goal is to remove as much as possible of the potentially radioactive dust. [Answer] Others have covered the necessity of keeping radioactive dust off of and out of the explorers. I will only add that KN95 masks and other specialized filter masks used for commercial, non-medical applications (construction, painting, etc.) seem likely to be the highest availability for creating jury rigged fallout protection gear in your hypothetical scenario. In terms of radiation detection, it's probable that national or local law enforcement offices and airports will have basic instruments for detecting radiation along with some level of training in their use. Beyond that, IIRC, some mineral collectors ("rockhounds") [use radiation detectors](https://howtofindrocks.com/geiger-counter-for-rockhounding/) as part of their hobby, so a few can possibly be supplied by them. As an option of last resort, [scintillator](https://en.wikipedia.org/wiki/Scintillator) crystals may be found in high schools for demonstrating radioactivity to students from which [instruments](https://en.wikipedia.org/wiki/Scintillation_counter) may be jury rigged. [Answer] Several good answers address the gear considerations. Some considerations around *who* to send: * Older is better than younger. Lifetime radiation dose is more of a problem earlier on in life than much later in life. * Sterile is better than fertile. Getting a big radiation dose is more of a problem for the breeders and their offspring. Conveniently, this dovetails into the first consideration nicely. * More-experienced is better than less-experienced. All other things being equal, it's probably less of a problem to send out people who remember life before the Vault, compared to people who have never seen the sky. All of that adds up to your wasteland raiders being a gang of raging grannies, which surely we can all get behind. [Answer] **Preliminaries** The irradiation danger depends on the energy of the bombs, their make up and the altitude of explosion For a 15-20kt range, uranium/plutonium A-bomb (like the Hiroshima/Nagasaki), exploding at 500m: * the area of total destruction is about 2km, you have no reason to get there, unlikely that something that one needs survived intact * the "hot area" for about 1mo has a radius of about 5km * the fallout is minimally dangerous due to the high altitude of explosion (soil, water and burnt matter will get sucked in the nuke mushroom's stem and will form a black rain, but the contamination doesn't seem lethal) The [neutron bomb](https://en.wikipedia.org/wiki/Neutron_bomb) design chooses too maximize the radiation damage and lower the blast one. Neutron and γ-ray bombardment doesn't create appreciable amounts of [induced radioactivity](https://en.wikipedia.org/wiki/Induced_radioactivity) over times longer than a few days. For ground level explosions and higher energies - YMMV, but the "a city which has had multiple nuclear bombs set off" and the existence of "radioactive areas to explore" suggest the city is not leveled up by nukes, thus it's unlikely that under/ground level or very powerful explosions were used. Furthermore "key parts of the city, hence why they were nuked" suggest [tactical nukes](https://en.wikipedia.org/wiki/Tactical_nuclear_weapon) in the kiloton range... ummm... about the same as Hiroshima/Nagasaki **Some data** [Rediscovery of an old article reporting that the area around the epicenter in Hiroshima was heavily contaminated with residual radiation, indicating that exposure doses of A-bomb survivors were largely underestimated](https://academic.oup.com/jrr/article/58/5/745/3926493) > > Table 6 summarizes the results of the survey of non-hibakusha who were entrants. Of these 525 non-hibakusha, 230 (43.8%) showed disorders. These non-hibakusha consisted of 405 ordinary people and 120 firefighters from Asa-Machi, north of Hiroshima City. The firefighters entered Hiroshima City at 8 a.m. on 7 and 8 August 1945, and they were engaged in rescue of hibakusha and the maintenance of roads. They finished their work at 4 p.m. Their working areas were from Yokokawa Machi (1.5 km north of the epicenter) to the epicenter to Yamaguchi Machi (1.0 km south of the epicenter). They worked for 2 days, but some worked for more than 5 days to search for lost persons and on other duties around the epicenter. They did not drink river water, because countless bodies were floating on the rivers. One to five days after returning home, a lot of the firefighters suffered from fever, diarrhea, sticky bloody stools, bleeding from the mucous membrane of the skin, loss of hair, and generalized weakness. These symptoms are the same as those of the A-bomb radiation sickness from which the hibakusha suffered. The proportion of symptoms was high in those who entered the central area within the 20 days after the blast. The proportion was extremely low in those who entered the area after 1 month. Among the 525 non-hibakusha, 26.4% got a fever (this was severe and lasted for more than 3 weeks for 10.3%, i.e. approximately two-fifths of the fever patients’, so there is no ambiguity), 30.8% suffered from acute diarrhea, and 11.6% complained of high temperature and sticky bloody stools, as if they were dysentery patients. Several days to 3–4 months were needed to get rid of the symptoms. Fortunately, no victims were found in entrant non-hibakusha including firefighters. > > > **Conclusions** * you aren't likely to find anything of value in 1.5-2 km radius, so don't get there * if it's critical for the survival of the community, many may chose to make the sacrifice and go *unprotected* within a 5km radius from the epicenter in the next days of the explosion. Some of the will possibly die, others will get 3-4 weeks of acute radiation disease and recover, with some increased risk of cancer down the line * few days after the explosions, decently closed suits and N95 masks may be all that's necessary as PPE, \**iff* *decontamination countermeasures are followed on return* (get them moist to fix the dust, strip them down, take a shower and wash them) * 3 weeks to a month after the explosion, it may be a bit risky to venture in the zone, but the chances of dying soon or suffer greatly later are probably much less than the chances of dying from the lack of the supplies they seek. [Answer] ## Stay Up High In a post-nuclear-apocalypse city, there will be (remnants of) skyscrapers and other tall buildings. These become your highways. The big radiological concern is avoiding places where contamination (radioactive dust, basically) will ***collect***. Contamination is more likely to collect in a depression, or a low space with limited outflow. So the subway is probably... not a good place to be. But tall buildings with broken windows are going to experience high winds, rain penetration, etc. There will probably be less contamination there. So your society will build rickety, terrifying bridges between the shattered husks of the skyscrapers. For safety. ## Source Food Carefully Many plants are highly tolerate of radioactively. Likewise, many game animals are short lived, so their cancer risks are relatively low. This means that wild plants and animals should be highly suspect. Feral pigs are going to move into your city, but you probably don't want to eat them, since they could ingest contaminated material. You could, however, capture wild animals and raise them in environments you identify as being low in contamination - so think less hunter, more herdsman. ## Fuel and Indoor Air Quality Cooking and heating fuel impacts both your food and your interior air quality. Sources upwind of the blast zones would be best, and you might invest in building a rocket stove for every home - smoke is vented directly outside, and you can cook on the top of it. To avoid contaminated smoke while foraging - avoid traveling in winter / bad weather, and bring dry rations so you can avoid smoke exposure altogether. ## Exposure Maps If you can get your hands on or construct a Geiger counter, your explorers will probably map out the areas of high and low radiation near their homes. These will shift over time, but everyone will probably have a good idea of the safe zones based on repeated excursions mapping the radiation environment. [Answer] How dystopian do you want your story to be? If it's an environment with harsh penalties for crime then you have a instant source of candidates to send into the radioactive wasteland. What would make these people go into these places knowing it's going to be a death sentence? Use their families as leverage. This way, the technology they have available doesn't need to be fantastic. The characters in the story just need to be desperate enough to set up a system that has no qualms pushing people out into the radiation "for the greater good". ]
[Question] [ What battlefield/tech conditions would necessitate the use of trench warfare in a modern or semi near future setting? One thing I was considering was the significant advancement of railguns/AT guns that would effectively shut down heavy armored assaults. Past a certain point the incoming shell is just coming in to hard and fast, and any added armor is going to make your tank way to slow. Combined with improved anti air capabilities it would significantly hamper the ideas of maneuver warfare, at least in theory. In the setting I'm working, satellites and space based capabilities aren't really a thing. In fact no one on the planet has the capability to mount and operate a satellite for more than a few minutes at maximum (think autonomous anti satellite batteries in orbit that will basically intercept anything past a certain altitude). One of the pitfalls of trench warfare in the modern era was the increased use of heavier caliber artillery and things like MLRS/rocket artillery, though at the same time close in weapons systems have been making some major progress in recent times. The combat that would be taking place would be between two peer forces, and things like nuclear weapons for the sake of argument are not a concern. Basically what battlefield conditions would need to happen to force the concept of maneuver/high mobility warfare to grind down to a well defined front line that's just sort of stuck. [Answer] **Urban warfare.** [![city](https://i.stack.imgur.com/nz1KU.jpg)](https://i.stack.imgur.com/nz1KU.jpg) <https://mwi.usma.edu/think-army-can-avoid-fighting-megacities/> <https://www.defensenews.com/digital-show-dailies/ausa/2016/10/05/army-chief-soldiers-must-be-ready-to-fight-in-megacities/> > > "You're seeing a massive growth right now, as we speak, of > megacities," Milley said. "Today, an example of a megacity is Seoul, > South Korea, with 27 million people, that has urban sprawl essentially > from the [demilitarized zone] all the way south of Seoul, and it is > this massive urban belt and complex." > > > The Army has been designed, manned, trained and equipped for the last > 241 years to operate primarily in rural areas, Milley said. > > > "In the future, I can say with very high degrees of confidence, the > American Army is probably going to be fighting in urban areas," he > said. "We need to man, organize, train and equip the force for > operations in urban areas, highly dense urban areas, and that's a > different construct. We're not organized like that right now." > > > A battlefield that is a big city is a battlefield that could turn into a standoff. The linked article walks through the complexities of fighting in a city - the three dimensional terrain extending above and below ground and the masses of people. Free swinging force mobility is not possible in a big city. Megaweapons could break a standoff if you are willing to level the city and kill the civilians in it. If you have opposing forces who are unwilling or unable to do that (or more likely one of each), then you could easily wind up with the sort of standoff you are talking about. [Answer] # You have to eliminate mechanization Before automatic weaponry, the combatants walked in the open on the battlefield, or hunkered down behind cover that was erected — or existed — on the surface. Then weapons evolved to the point where you could not move about in the open on the battlefield without getting instantly puréed. The counter to this was trench warfare. Now no-one could move anywhere, and they bogged down in the trenches. This is the state of affairs you want to exist in your story. So, what was the "remedy", that made made trench warfare obsolete? It was... [![enter image description here](https://i.stack.imgur.com/EmJWs.jpg)](https://i.stack.imgur.com/EmJWs.jpg) *Mark IV tank ([image source](https://en.wikipedia.org/wiki/Mark_IV_tank))* ...and with this — *military mechanisation* — trench warfare's quite brief and bloody career was over. --- Military mechanisation is a product of industrialisation and mass production. Without heavy industry, mechanised units have to be shipped in. If no production capability exists, and/or that the units have not yet been shipped in, then the forces have to rely on whatever can be carried. Automatic weapons can be hand-carried, or carried in light vehicles, making the danger on puréification real. But without armoured vehicles in your setting, then then you have enabled trench warfare. --- Hence, if you want to enable trench warfare in your setting, you have to set the story someplace where... 1. automatic weaponry exists, with indirect fire as as a nasty bonus 2. there is no significant amount of armoured mechanisation ...i.e. on **off-world colonies, before industrialisation has been achieved, and before heavy shipments have arrived**. Competing colonies on Luna, Mars, Pandora, the Andromeda Galaxy, at the very start of the colonisation, where the people are waiting for the heavy stuff and the fabricators, there you can make trench warfare credible. If you want to be absolutely sure no vehicles — or very few — get involved, make it so that all electronics in them get knocked out. Apply suitable hand-wavium here. [Answer] Remember trench warfare is what happened when neither side could get the upper hand, they dug in to hold what they had and used their fortifications to launch attacks on opposition lines. To get there on the modern battlefield you need to kill both infantry unit mechanisation and airpower as decisive battlefield factors, then the frontline can bog down into trench warfare. Your idea about ubiquitous anti-armour weapons like railguns is very useful for removing mechanisation from the battlefield while not necessarily impacting it's role in *supplying* the battlefield. AA cover would need to be total in order to keep aircraft from upsetting the balance of arms at the front, this actually happened for a time during the [Fourth Arab–Israeli War](https://en.wikipedia.org/wiki/Yom_Kippur_War) allowing the Egyptian army to maintain their beachhead on the Eastern bank of the Suez Canal. Advanced artillery, including but not limited to squad portable mortars and rocket artillery, and missile systems are another challenge to maintaining a stalemate and are harder to explain away. If you can fire over the horizon then you can devastate enemy trenches without coming under fire and it turns into a contest of who can mass artillery fastest, and/or who can slip target acquisition teams through the lines and follow up with the most cruise, or ballistic, missiles. You'll need to work around that as well, oil shortages will go some way to explaining the lack of longrange liquid fueled missiles but they do little for shorter range solid fuel rockets or propellant based shells. You'd also get the cool mash up of troops using railguns whose batteries are charged by generators running off steam engines. [Answer] You need to make sure of a few things: * artillery should not have the accuracy and ammunition to hit trenches reliably. If all it takes is a spotter giving grid coordinates to artillery and an airbursting shell can clear several meters of trench its not going to work. * aircraft should not have the leniency and accuracy to easily hit the trenches or the support infrastructure that maintains the trenches. -a cost-effective method has to be present to deal with vehicles, without making this method the new weapon to mount on vehicles. The biggest hurdle will be accuracy. If your opponent can pinpoint a location they can start bombing it with modern bombs and ballistics, which makes it very hard to have any static defenses. This makes railguns a problem, as they would simply have the accuracy (and range) to become the new artillery instead (and smaller ones could efficiently kill hundreds of infantry with little ammo waste). Using decoy shots you can then also sap the enemy CAS from its ammunition and then destroy any static target even without GPS. Possible solutions for that accuracy: * advanced electronic warfare dilutes all information over time. This makes it hard to consistently use computer data to target a specific area. * the war has lasted a long, looong time. Modern technology requires a lot of precious materials and worldwide processing to make, and the high-tech stuff has simply been spend. This is in part what happened in WWII, where sometimes worse tanks were designed than their predecessors because of limitations in factory space, technical know-how or resources. * you have effective methods to hide your trenches or make it unclear what are the "real" trenches and what are fake trenches that can be build in a day. This would also be an effective help against modern armor, as active protections like the Trophy system will become more numerous and capable of reducing the impact of high velocity shells as well. That means the modern battlefield would devolve more to a WWII style era. But how to truly deal with vehicles? A simple solution would be a lack of proper fuels. Battery powered vehicles have their uses but the weight of the batteries would limit the armor they can bring (ignoring the potential for super-capacitors). There is actually a method for vehicular trench warfare. Modern tanks cant use trenches, they need a pre-prepared position they have to drive into, fire, drive back out. That driving in and out of the position takes a lot of time compared to popping up and down a trench. So multi-legged walkers could be a great tool there. You dig a massive trench for the vehicles to walk through, they raise themselves and only show their turret to take a shot and immediately pop back down again. This limits the amount of armor they need to "topside and front-facing" as they would never expose more, and any flank attack that made it to the trench would fall in and then have to deal with the tanks that cover the mechs. An additional advantage of mechs is that legs are far superior in recoil absorbtion, allowing a mech to mount a bigger gun for its weight class. The sheer size of the trenches and speed that a well-designed mech could muster would make artillery barrages tough to pull off, most would simply hit an empty trench that can be re-dug quickly. [Answer] With fast enough and powerful enough point defenses, it *may* be possible to eliminate the threat of aircraft, drones, people walking around, various kinds of missile, shell and rocket, etc. With powerful enough antitank weaponry, you might be able to render the use of armor futile, too. For those generals and strategists who still want to be fighting wars gone past, the solution would appear to be to dig holes and hide in them, so maybe you might be able to get your trench warfare. Personally though, I don't think that this will work very well without having other serious technological restrictions. * railgun launched supersonic projectiles still has the potential to overwhelm any active defensive system and penetrate a significant distance into the ground. * supersonic and hypersonic rocketry may also be able to evade defenses and deliver various colors and flavors of warhead. * small intelligent drones could evade both detection and defenses and penetrate fortifications and damage material and kill personnel in them. None of these things are particularly farfetched, and the latter is likely to completely upend any many strategies and tactics that you might try to adapt from current or past conflicts. > > In fact no one on the planet has the capability to mount and operate a satellite for more than a few minutes at maximum (think autonomous anti satellite batteries in orbit that will basically intercept anything past a certain altitude). > > > There's a separate question in there ("how can I prevent a planetary civilisation from reaching orbit, without otherwise interfering with them?") but you should be aware that operating antisatellite weaponry from the surface of a planet is hard but by no means impossible. Being able to launch satellites *at all* implies ready access to ICBMs and various kinds of long range hypersonic and hypervelocity strike weapons, few of which can be usefully defended against by digging a hole and hiding in it. Take a leaf out of the *Altered Carbon* books, and have your satellite battlestations take exception to anything flying more than 100m or so above the surface. [Answer] **Extremely precise RailGun "AA" Bateries** In a near future Railguns have become widespread in the military, and projectile detection and fire precision have dramatically increased. As such, future AA bateries are now able to shoot 99% of airborne targets at dozens of miles away. This includes planes, satelites **and artillery shells**. Without means of indirect shooting (artillery, airborne bombs, missiles) what remains is old style line-of-sight shooting, so the best defense is to stay hidden. Welcome back Trench Warfare :-) [Answer] The main thing that promoted trench warfare in WWI were the ability to move and supply a large amount of soldiers to create a solid series of lines of defense across an entire front e.g. railways, canned food, the predominance of certain weapons - machine guns firing enfilade could mow down the majority of an almost unlimited amount of enemies attacking at once, making it easy to defend even when significantly outnumbered, industrialization to mass produce the weapons/ammo needed in sufficient numbers, and no suitably advanced/developed way to reliably bypass such lines of defense that didn't end up stalemated - high profile failures like Gallipoli can also make such attempts to bypass the front lines or open new ones politically unfeasible even if they would be militarily advantageous. So in terms of dealing with ground based hardware you would want a relatively cheap to manufacture weapon (or combination of weapons) so your defensive lines can have plenty of them, that they are easy to use (so you can arm up lots of conscripted civilians without spending an age training them), and can take out any ground units that advance rapidly, but is heavy enough or requires a short set up time before firing so it can be moved to a new defensive position relatively quickly, but it can't be used when assaulting (unless you are Jesse Ventura/Arnie), with decent fire rates so defenses can't be overwhelmed numerically very easily, and with relatively cheap and easy to produce ammunition. Note that I don't think the literal trenches of WWI are likely in the future, something more in the elastic defense mold would seem to trump it - lots of small defensive positions that are abandoned if the enemy comes in strength with enough defense in depth to let the enemy extend themselves while giving time for a counter attack to be organized. This sort of dispersed defensive set up tends to make artillery and other forms of massed fire less effective as well. Assuming that the next problem is to deal with other modes of bypassing these defensive lines - paratroopers and other aerial threats, and naval and amphibious attacks. In the air I think it should be feasible to create a similar stand off - with enough SAM threats on the ground in the layers of defense and enough AAM capability to rapidly move to counter a concentration of enemy air power around a developing attack you could see a stalemate where after long enough the two sides might largely stop producing bombers or close support aircraft (replacing them with more SSM launchers behind the lines to work as guided artillery instead of ASM). You could even see a scene describing the first (and only) attempt at a paratrooper drop early in the stalemate having them all wiped out before even leaving their aircraft (paralleling Gallipoli). Depending on the location/nations involved it would also need a similar naval standoff to develop, with both sides being able to defend their supply lines and coasts, and some way to make it so the defensive side is favoured in naval battles. For example one side could be following a fleet-in-being doctrine if outnumbered (but not by too much), as long as the air defenses of the port(s) in question are solid enough (a lot of SAM sites and plenty of anti-missile defenses). Alternatively long range amphibious landings might be ruled out as too difficult to keep supplied safely for long enough to make a breakthrough, and smaller ones as being strategically useless as the defender would quickly set up a new line of defense, so the attacker would expend a lot of resources for little practical gain. Of course such situations tend to generate lots of innovation to try to break the deadlock - taking WWI as an example the obvious one was tanks, also using planes for a myriad of roles - scouting, strafing, bombing and air supremacy, massive amphibious landing, doctrinal changes such as advancing under a creeping barrage of artillery, massive sapper operations, etc. The problem with these tends to be they take time to develop to the point they become truly effective - in this example some of them took about 20 years after learning the mistakes and improving the engineering from WWI and maybe even then a couple of years of "live fire" tests to reach their full potential. As you suggest something like a railgun with a reasonably large battery in order to power the magnets could be an option for a weapon that is better suited to defending than attacking, especially if it has some target spotting/aim assist built in so even a novice can use it to attack any moving targets then this could act as the base for the ground side of the stalemate, and then some missile targeting advance that makes it easy to clear the skies and seas of enemies, and maybe tanks as well, without making much difference to targeting small ground targets (i.e. people in foxholes/bunkers/buildings) would do most of the rest. ]
[Question] [ Imagine that you're the admiral of a fleet of warships in orbit around Saturn. You need to capture targets on Titan, the largest moon. (This could also be applied to, say, Venus or one of the gas giants. This is an example. EDIT: this has been pointed out to me as false. This could work on Earth or Titan; that's about it.) You realize that your opponents live in airships (filled with hot air, not helium/hydrogen), not surface habitats! This makes invasion extremely tricky, as you have no airships with which to board these ships. Instead, you decide to try to pop the envelopes from your comfy orbit. ### The ideal result * The airships have all been forced to land. * Few, if any, lives are lost. (in other words, killing them all is not an option. Just put a small hole in the balloon so that they can't keep the inside hot enough to stay afloat without massive energy expenditures.) * Minimal resources are expended. (so nix on taking a troop transport and crashing into the envelope. Using just a projectile dropped from orbit is ideal.) * The life support of the habitats still works, so the fleet isn't forced to choose between genocide or rescuing thousands of people. Please note that the standard tools the fleet has for orbital are not very great for the job because they are massive, heavy "Rods from God" made for absolutely obliterating surface targets. You will need to **repurpose an object you already have** to be able to complete the mission. Good luck. --- EDIT: I've been asked to give more information on the resources available. To respond to @DWKraus's specific questions: * The tech difference is... interesting. To put it simply, the Titaneans in my story don't *have* all the tech that the attackers do, but they know what it does and how to exploit weaknesses in that tech. See another question of mine about this story: [How would one hack a battleship in space warfare?](https://worldbuilding.stackexchange.com/questions/202194/how-would-one-hack-a-battleship-in-space-warfare) * They don't care a ton about deaths, ideologically, but their goal is to be in control, not to destroy. They don't want the Titaneans dead, they want them to come under their rule. * Flight packs and drones are viable solutions, too! Orbital bombardment was the best solution I could think of on my own, but I am open to more creative ways to pop a hole in the envelope. The main limitation is that the resources used need to be things they might plausibly already have since they can't afford to wait for a supply mission. * The ground troops are not robots. Let's just say that humanoid robots never caught on in this timeline (there's a story behind that, but this is the simplest way to put it). Now, to @Dragongeek's question: why not just use laser arrays? Um... I don't know. From my perspective as an author, it's because that's not nearly as cool as orbital bombardment, but I'm going to need a more convincing reason. I'll probably put out a separate question about that. Just assume that hitting the envelopes with lasers from orbit is not an option. [Answer] If my superiors "don't care a ton about deaths" I would target one airship and use it's destruction as an example to force the other airships to surrender. Rods from God are perfect for this even if the airships are to small to target accurately. Have your engineers hollow out a cavity inside the rods and pack them with explosives. Then target a volley of these Explosive Rods From God as accurately as possible at an airship. When the rods reach an altitude 1k(or whatever your engineers deem appropriate) above the airship the explosive detonates and fragments the rod into a cloud of chunks that rain down. A volley of these could cause serious problems for any balloon supported airship in the area. [Answer] **Ballistic Frozen Meatballs.** It's a well known fact that meatballs are a universal constant: > > G'Kar: It's an Earth food. They are called Swedish meatballs. It's a > strange thing, but every sentient race has its own version of these > Swedish meatballs! I suspect it's one of those great universal > mysteries which will either never be explained, or which would drive > you mad if you ever learned the truth. > > > ([Babylon 5](https://en.wikipedia.org/wiki/Babylon_5), by J. Michael Straczynski, tribute to [Douglas Adams](https://hitchhikersguidequotes.tumblr.com/post/17319713714/it-is-a-curious-fact-and-one-to-which-no-one)) Dropping them in batches by hand from an orbital posture might take some tricky calculations, but if you've got a space fleet at your disposal, I'm sure you can aim well enough. Will produce many holes of sufficient size to "encourage" airships to land. [Answer] **Divert the rings.** [![titan and rings from cassini](https://i.stack.imgur.com/PL96i.jpg)](https://i.stack.imgur.com/PL96i.jpg) What a sweet photo. But now - on to the mayhem! Your ship snuggles down into the ring and then begins to move along it like a lawnmower. Each chunk you encounter is electrostatically hurled towards Titan, which is following you a couple of blocks away. It is effectively a meteor shower on Titan. You have a lot of ring to throw. Most will not hit the airships but the people on Titan will see them coming down - because the things you throw will be glowing on re-entry like meteorites do. It will be spectacular and scary. After an hour or so you will pause and let the Titan folks know what you are doing, in case they have not figured it out. You will give them another hour to land their balloons. If you dont see them landing you will turn back on the bombardment. [Answer] Who owns the orbitals, owns the planet. A battlefleet above an unprotected civilian population does not need anything as crass as physical weapons. A simple radio call should suffice. The threat of obliteration should be enough to let the airships do whatever they demand, since everybody knows that they can be grounded or destroyed, at any time. Any reasonable populace will do what is asked of them, unless they have to fear cruelty by the invaders, or it's a religious zealots situation, but your scenario doesn't look like that. (minimal casualties etc.) [Answer] Aerial depth charge. Fill up a missile with more explosive and shrapnel than normal and drop it from orbit. Just have to get close enough to create a pressure wave to either damage them enough to land or make being higher in the atmosphere dangerous. [Answer] Just use the rods themselves. A pack of a thousand rods could easily deliver a yield of around 10% to 100% of the Little Boy nuke. That will conjure a huge mushroom cloud - you don't want to hit the airships with that. But you do want them to be in the vicinity of the cloud so that the blast waves shake them up real good. The airships will be damaged and will have to land for repairs. ]
[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/195269/edit). Closed 2 years ago. [Improve this question](/posts/195269/edit) So let's imagine a rogue planet. It's far from any sun, and the very little light it receives from the stars is way too low to sustain any form of photosynthesis. Thankfully, this planet also has a lot of volcanic activity. Thanks to its thick atmosphere and aforementioned volcanic activity the surface of the planet is warm, and its oceans are liquid. It is very similar to Earth from geological perspective, just with more volcanic activity. There are already simple organisms living deep underwater around thermal vents, and in time, they will evolve into more advanced organisms similar to what we know from Earth's oceans. But that's the ocean, what about the land? How would the land life look on a world without sun, where the only sources of energy are volcanoes and geysers/hot springs? How would the organisms evolve and adapt to the conditions of this world? Would it even be possible for there to be any advanced land life in such a world? As I said before, the climate on the surface is warm, with temperatures ranging from 20C to 40C depending on the weather. The geothermal sources of energy are abundant, ranging from large geysers and hot springs to lava lakes and volcanoes, but they are the only source of energy outside the ocean. How would the life adapt to live in such conditions? [Answer] You do have a minor problem. Oxygen. Earth-based life forms depend on atmospheric oxygen for energy, something that would be very hard to imagine on your planet. It is for sure the land life would not depend on oxygen. The fact that aquatic life on earth CAN survive without atmospheric oxygen is now established, but it is based on the ability of the organism to extract [oxygen from water](https://science.nasa.gov/science-news/science-at-nasa/2001/ast13apr_1/). > > Deep-sea bacteria form the base of a varied food chain that includes > shrimp, tubeworms, clams, fish, crabs, and octopi. All of these > animals must be adapted to endure the extreme environment of the vents > -- complete darkness; water temperatures ranging from 2°C (in ambient seawater) to about 400°C (at the vent openings); pressures hundreds of > times that at sea level; and high concentrations of sulfides and other > noxious chemicals. > > > The ability of life to tap such geothermal energy raises interesting > possibilities for other worlds like Jupiter's moon Europa, which > probably harbors liquid water beneath its icy surface. Europa is > squeezed and stretched by gravitational forces from Jupiter and the > other Galilean satellites. Tidal friction heats the interior of Europa > possibly enough to maintain the solar system's biggest ocean. Could > similar hydrothermal vents in Europa's dark seas fuel vent ecosystems > like those found on Earth? The only way to know is to go there and > check. > > > So yes, advanced life forms can survive without photosynthesis, but this begs the question be asked "Where and how did these other higher order life forms evolve? Did they evolve around the vents, or did they evolve elsewhere and return to the vents?" Any sea life that depends on the [amoeba in the evolutionary chain](https://carnegiescience.edu/news/amoeba-may-offer-key-clue-photosynthetic-evolution) will depend on photosynthesis. > > Clearly the events that gave rise to chloroplasts and mitochondria > changed the world forever. But it is difficult to research the process > by which this happened because it took place so long ago. One strategy > used to elucidate the way in which this process evolved has relied on > identifying organisms for which the events that resulted in the > conversion of a bacterium into a host-dependent organelle occurred > more recently. > > > Nowack and Grossman focused their research on a type of amoeba called > Paulinella chromatophora, which contains two photosynthetic > compartments that also originated from an endosymbiotic > cyanobacterium, but that represent an earlier stage in the formation > of a fully evolved organelle. > > > The NASA article goes on to say, at the end, > > Editor's note: Michael Meyer, the Astrobiology Discipline Scientist at > NASA headquarters remarks: "Right now, the hydrothermal systems are > dependent on oxygen as the electron acceptor, which comes from > photosynthesis. But it does raise the possibility of a thriving > hydrothermal system in an anoxic environment, presumably driven by H2S > going to elemental sulfur (and not sulfate)." > > > So it seems the author is proposing a life form that can survive on H2S and not H2O. That is, it would not be dependent on oxygen in the atmosphere, but sulphur in the atmosphere, which would be plentiful on your world. And sulphur hexafloride is an excellent [greenhouse gas](https://www.epa.gov/ghgemissions/understanding-global-warming-potentials), able to retain heat much better than CO2. > > Chlorofluorocarbons (CFCs), hydrofluorocarbons (HFCs), > hydrochlorofluorocarbons (HCFCs), perfluorocarbons (PFCs), and **sulfur > hexafluoride (SF6)** are sometimes called high-GWP gases because, for a > given amount of mass, they trap substantially more heat than CO2. (The > GWPs for these gases can be in the thousands or tens of thousands.) [emphasis mine] > > > It turns out that sulphur has, indeed, [been proposed](https://en.wikipedia.org/wiki/Hypothetical_types_of_biochemistry) as an alternative to oxygen as an hypothesis, but not completely proven, except at the bacterial level. > > Sulfur is also able to form long-chain molecules, but suffers from the > same high-reactivity problems as phosphorus and silanes. The > biological use of sulfur as an alternative to carbon is purely > hypothetical, especially because sulfur usually forms only linear > chains rather than branched ones. (The biological use of sulfur as an > electron acceptor is widespread and can be traced back 3.5 billion > years on Earth, thus predating the use of molecular oxygen.[20] > Sulfur-reducing bacteria can utilize elemental sulfur instead of > oxygen, reducing sulfur to hydrogen sulfide.) > > > So yes, it is well within speculation given our current knowledge that a significantly evolved life pyramid could evolve on your planet, based on sulphur and not carbon-oxygen. The heavy concentration of sulphur in the atmosphere would, in fact, explain the relative warmth of the atmosphere and the lack of radiation back into space that would otherwise cool the planet. These creatures could be hypothesized to be air-breathing, very similar to Earth creatures, except that they breathe sulphur and not oxygen. But can we even pretend to know what their 'blood' and their 'lungs' would look like? Methinks not. **ADDENDUM EDIT** There is, in fact, [evidence](https://scienceillustrated.com.au/blog/science/early-life-on-earth-had-sulphur-based-metabolisms/) that a more evolved sulphur-based life form did exist on earth. > > Researchers from the University of Western Australia (UWA) and Oxford > University have unearthed the best preserved sulphur-based > microfossils on Earth. The 3.4-billion-year-old fossils consist of > carbonaceous cells, along with the protective sheaths that housed some > of these cells. > > > > > The discovery provides strong evidence for early life on Earth > subsisting on sulphur, rather than oxygen. “These are now the oldest > well-preserved microfossils on Earth and the discovery bypasses much > of the controversy that has surrounded previous, more poorly preserved > microfossils of about the same age,” said postdoctoral research > fellow the Dr David Wacey from UWA, lead author of the paper published > in Nature Geoscience. > > > [Answer] A very important component of this ecosystem (which is similar to that which we expect on the far side of most tidally locked habitable planets orbiting red dwarf stars) is the **[anti-solar cell](https://www.ucdavis.edu/news/anti-solar-cells-photovoltaic-cell-works-night)**. You may have read of Bedouins who, in ancient times before conventional refrigeration, made ice in the Sahara by exposing pans of water to the starlit sky. Producing ice means extracting usable energy, and the anti-solar cell does it more directly. Still, I was very *surprised* by the amount of power it is said to be able to produce! With this level of power generation, we can expect these planetary darksides to be adorned with forests and fields not so different from our own - less efficient, to be sure, and slower growing, but still sustaining interesting ecologies of the night. We might even suppose that, as bacteriorhodopsins eventually evolved into our photoreceptors, that the animals of these worlds might see by darkness - by their ability to radiate small amounts of heat, via infrared photons, from specific parts of their retinas. (Retinas in a loose sense - I realize I should take another look at the capabilities of pit vipers. We always think of them as seeing the heat from prey, but what about seeing the cold of night?) [Answer] ## REAL Alternative Energy: I can't speak of what the biochemistry and final electron acceptors of this world will be, but it could exist in your thermal environment if you have organisms using biological [heat engines](https://en.wikipedia.org/wiki/Heat_engine)/[thermoelectric generators](https://en.wikipedia.org/wiki/Thermoelectric_generator)/[(electro)mechanical](https://www.researchgate.net/profile/Muhammad_Hassan_Khan_Niazi2/publication/284347416_Energy_Harvesting_Model_From_Tree_And_Grass_Movement_Using_Piezoelectric_Effect/links/5f9c616292851c14bcf6352d/Energy-Harvesting-Model-From-Tree-And-Grass-Movement-Using-Piezoelectric-Effect.pdf) energy harvesting instead of chemosynthesis. I'm not saying chemosynthesis wouldn't still be big, but it isn't going to be the driver of eukaryotic organisms. Your plants will resemble bio-machines. They may even use electricity (why not?) Our life evolved to take advantage of the endless sunlight streaming down like manna from heaven, but here that isn't an option. certainly bacteria could evolve, but complex multicellular life might need a little more to justify why they get big. Chemical energy would need a rationale as to why it moved and spread. For starters, your organisms would need to be bigger to take advantage of temperature differences between one place and another. Intense heat sources (vulcanism) mean that the large gradients of heat would be exploitable by fairly small multicellular organisms, but to take advantage of more subtle differences, pressure to evolve bigger and more complex structures would result in plant-like life that spread across the ground, and eventually spread upwards to make radiator-like "plants" conducting heat from the ground into the air (or vice versa). Once "plants" are scaling into the skies, why not take advantage of piezoelectric effects and have plants powered by the swaying in the winds of your volcanos, or prevailing winds from planetary rotation? If there is an equivalent to the jet stream on your world (a big if) then organisms would have pressure to grow really tall, then create fans to resist the winds. Now that you have organisms harvesting energy from the environment, the sky is the limit. The types of plants would depend on things like winds, and if the ground/air was cold or hot. So ecosystems would evolve. Everything your ecology needs is present. Would this harvesting result in biochemical reactions generating oxygen? Life doesn't use biomechanical power harvesting. At that point, you could justify all sorts of things. Organisms could even use electricity directly, storing chemicals to make power, or having mechanical batteries, or (most likely, given chemosynthetic ancestors) acting just like life on Earth, with mundane chemistry reactions powering organisms. The choices are yours. ]
[Question] [ I know that brain size is less important than structure and that human babies' brains are 27% the size of an adult's, but humans give birth to large brained babies. As a result, humans can't support the weight of their own heads for a few months, mature slowly and have a large pelvis. If a species had shorter pregnancies (about six months long), larger skulls and smaller babies than humans (almost half their size), could their brain size increase rapidly until adulthood to the point they end up being smarter? In this case, an average adult is slightly taller than a human and their brain structures are somewhat similar, but with better long term memories. [Answer] **Yes.** [![preemie](https://i.stack.imgur.com/5M4o3.jpg)](https://i.stack.imgur.com/5M4o3.jpg) <https://www.insideedition.com/headlines/21257-premature-baby-beats-the-odds-to-survive-despite-being-born-with-feet-the-size-of> Here is a very little baby. It was born at 6 months gestation. Issues which make such early babies less likely to survive involve lung and digestive tract maturity but there is nothing hardwired into the mammal body plan that means you need 6+ months to get working organs - puppies and kittens this size breathe fine after an even shorter gestation. Preemies this small might grow up developmentally disabled. Or they might be normal! Your human-types can have very tiny babies like this one, but which have matured their lung, mouth, digestive tract etc in the manner of other mammals to help them survive once born. The babies, their heads, brains and whatever other parts interest you continue to grow ex utero. They get as big as your story needs. [Answer] **Yes.** This is what marsupials do all the time. Marsupials are born at a fraction of the adult size, and are born with very loose skull bones (akin to a fetal stage of a placental) that would allow for the brain to expand much more than a placental mammal that has to fit through a birth canal. Most of the nutrients a marsupial baby consumes come not from the placenta, but lactation. The brain goes through most of its development and growth outside of the womb. Marsupial pregnancies are often incredibly short, going from fertilization to birth in just **11 days**. Marsupial brains are often characterized as smaller than placentals, but the strange thing is that marsupials have a greater potential for developing large brain size than placentals. Exactly why they never took advantage of this is still unknown. Also, [the birth canal hypothesis may not be right](https://www.sciencedaily.com/releases/2012/08/120827152037.htm). One line of thought now is that human babies are born at a relatively helpless, premature stage not because if they stayed in the womb any longer they would be too large to give birth to safely, but because if they stayed in the womb any longer their demand for nutrients would be a serious threat to the mother's health. In placentals the baby is essentially a parasite on the mother for the earliest stages of its life, and human infants with their large brain demand a lot of calories. Giving birth to the baby gives the mother more control over how much nutrients she gives to the baby and allows the baby to be fed external sources of food rather than just parasitizing off of the mother. ]
[Question] [ An unmanned, AI-controlled, terraforming ship arrives at an earth-like planet (i.e in the goldilocks zone of its star, with a magnetosphere, an atmosphere, plenty of liquid water, earth-like gravity, etc.). Despite this habitability, the planet has not developed any life at all. The terraforming ship sets to work and succeeds in making the planet adequate for Earth-native species (altering the atmosphere composition for example). Now it is ready to introduce earth species to the planet in order to prepare it for a colony ship that will arrive in a few hundred years time [edit: some answers suggest more time may be necessary to establish a functioning ecological pyramid, so specify more time if necessary]. What [ecological pyramid](https://en.wikipedia.org/wiki/Ecological_pyramid) will the ship introduce to create a viable, human-compatible [ecosystem](https://en.wikipedia.org/wiki/Ecosystem) and [food web](https://en.wikipedia.org/wiki/Food_web)? I assume that: 1. The terraforming ship will introduce the species in the temperate or Mediterranean-like zone of the planet, where humans can live comfortably. 2. There's not enough time for species to evolve before the humans arrive, but the terraforming ship could potentially genetically-engineer some existing earth-species, if necessary. I assume that the ecological pyramid will: 1. Include bacteria, plants, herbivores, carnivores and predators. 2. Create an ecosystem that can survive without human intervention, there being hundreds of years before the humans will arrive. 3. Support human-consumable food of the sort earth-based farms produce e.g. wheat, rice, potatoes, vegetables, nuts, dairy foods, fruit, meat. 4. Will be capable of supporting human useful animals like dogs, cats, sheep and horses, although the terraforming ship may wait to introduce them until the humans arrive if that's necessary. 5. May include birds, fish, spiders, insects and other species, but only if they are needed as part of the pyramid. It will not include any 'unnecessary' species. For example, there's no need for kangaroos or penguins. I'm happy to amend or clarify the question if it's unclear or I've made invalid assumptions. [Answer] **Spirulina. That's it.** <https://en.wikipedia.org/wiki/Spirulina_(dietary_supplement)> [![spirulina](https://i.stack.imgur.com/5JuZ4.jpg)](https://i.stack.imgur.com/5JuZ4.jpg) These blue green algae will happily take the ocean over and probably large swaths of the land too. They once ruled the earth and they still do very well. They are nutritious food for man and beast. Once the colonists show up they can harvest huge rafts of the stuff and use it as soil amendments, possibly with a soil starter culture. It is conceivable that this is all they would need, though probably not all they would want. And it makes for a good fiction - looking out over the gooey green ocean, thinking about a corn tortilla... [Answer] ### Lavender, Bees, Evergreen trees, Phytoplankton, Herrings, and some bacteria. That's it. Everything else can wait for just before humans arrive. This is the absolute minimum you'll need. * Lavender is high in nectar and flowers all year round in many climates. It's ideal for bees to gather nectar from and to maintain a bee population. * Bees you need to fertilise your crops. Let them be (ha!) for the moment, and let them grow in population. + I don't think you'll need spiders to control the bee population (they'll be limited by the lavender food supply), but that's an optional extra that may be needed. * Evergreen trees. Probably pine. Makes a nice construction material for the humans when they get there. * Fill the oceans with Phytoplankton. This consumes CO2 and generates oxygen in the water, allowing fish to eventually survive, this eventually gets in the air and makes the air nice and breathable for humans. + There are lots of types. Your terraformers should experiment and determine which one is optimal for the exact light / gas / mix of your planet. * Nitrosomonas or Nitrobacter to make nitrates, or convert nitrites to nitrates. There are many choices, just pick the best one which works experimentally on the exact atmosphere you have. (Is there ammonia gas or triple bonded nitrogen?) Examples are Azotobacter, Bacillus, Clostridium, and Klebsiella. * Herring fish (these eat plankton and [are good for humans](https://www.theguardian.com/lifeandstyle/2013/may/11/why-herring-is-good-for-you)). Without predators their population will be controlled by the plankton supply - they eat too much, they run out of either oxygenated water or food. These also make sure the plankton levels don't get too high - as too little CO2 and your planet will cool. Your terraforming bots should add phosphorus and potassium to the soil. Your settlers will arrive with fertilisers to help with creating good farmland. Your terraforming bots should also use geological processes to generate some initial oxygen if possible. Everything else should be grown in farms as much as possible. [Answer] ### **...and then a miracle happens...** I think you probably can't have a fully-functional and evolved ecosystem of an entire planet in a few hundred years. Sorry. It would likely take that long to build an underlying ecology of microorganisms, assuming they are all evolved to survive the local conditions. An ecosystem consists of so many moving parts that all need to be fully functional. It's not really sufficient to terraform a small region when you have an entire planet to deal with. What you can have is a widely distributed set of microorganisms (like blue-green algae) that have set the preconditions for an ecosystem. I doubt there would be time to fully establish a functioning oxygen atmosphere (the process requires the free oxygen to react with vast amounts of things like free iron in the environment, a process that took millions of years on Earth). Given hyper-efficient super organisms, perfect starting conditions, abundant raw organic materials (yes, there were organic materials before life was established on Earth) and a goldilocks planet, I'm going to say you can have an underlying microorganism population primed for more advanced organisms (still pretty simple, mostly plants in the ocean) in MAYBE 1000 years. Stuff has to grow, and even your terraforming ship would need raw materials to grow organisms, then dump them into the environment. There would likely be at least ONE event where some critical organism unexpectedly fails, setting the whole program back and requiring creative substitution. Your ship will need to be pretty smart, and even then biology isn't like physics. While it does follow chemistry and physics, it's a complex and unstable system of moving parts. To establish a functioning eukaryotic multicellular biome, you'll probably need your colonists to arrive with their squishy brains and extemporize the ecosystems together. That being said, once you achieve a stable, functioning ocean ecology (involving some fish, sponges and other filter feeders, etc) the problem of adding additional biomes becomes simpler. Once radiation is under control, plants can form the basis of ecologies and spread on the land. In a lot of ways, the whole process needs to recapitulate the evolution of life on Earth. The early plants will need to be simple and self-sufficient, and later you can get fancy, adding insects and other pollinating organisms, seed carriers, etc. If you want to establish an ecosystem in domes, the problem becomes simpler. These could be the 'seeds' for later biomes on the surface. I would study the attempts to have self-sustaining biospheres in buildings that have been made. So far, they've all failed. That doesn't mean they won't eventually succeed, but it just proves the process is a lot more complicated than we'd like it to be. [Answer] Cheat. There are a bunch of things that need to happen to have modern life happy on a planet, like the oxygen apocalypse. This happening "naturally" will take a long time. Have your terraforming ship land robots that build huge solar power arrays, that in turn release massive amounts of oxygen into the atmosphere. It can convert CO2, H2O or even Oxygen trapped in Iron or similar materials into free oxygen. You'll probably end up covering much of the planet in solar panels along the way, and it will still take a long long time. But your machines will be happy with a toxic-to-modern-life environment. As you do this, start growing life forms that can survive in the low-oxygen environment and help the atmosphere along. Any kind of photosynthesis will do. You'll want machines able to "print" various kinds of microbes and widely seed them to speed this process up, and libraries of such microbes you use in each phase of the process. Now, before you start any of this, your ship will have visited the asteroid belt. As an interstellar ship, it is going to be tiny, as energy budgets needed to travel between stars in "reasonable" periods of time are ridiculous. So it finds a broken protoplanet core like Davida and **builds** the rest of the resources it needs in the vacuum of space. This process will continue as the planet is seeded. Orbital solar collectors will beam energy down to the planet, reducing the amount of infrastructure you have planet-side. If the planet is short water, missions to the ice zone will land comets on the planet (note this could add millions of years to the time required to terraform; moving planet-scale amounts of water to a planet is a high-energy act). Or, if you are crazy, you could even drop multiple beanstalks from orbit, allowing for more efficient transport of water to the surface (reduce the time you spend boiling entire planet's oceans along the way). The dirt of Earth is the result of many many millions of years of work as well. So mass producing machines that mechanically grind up soil and have internal bioreactors to prepare might be needed. This process is going to be high energy, turning the planet into a hothouse, as you try to do in a mere 100s of years what usually takes millions. Cooling the planet may require extreme measures; blocking the sun with giant shades would be one step, but also using laser heat-pumps or increasing the radiant surface area of the planet with the beanstalks or more insane mechanisms. Fortunately, long before you have a habitable planet, you'll be able to manufacture space stations, or bases buried under the surface of a moon (radiation shielding), supplied by stellar orbital asteroid mining. Humans could arrive (or more realistically, be printed) long before you the planet is done. And in the relatively controlled environment of tunnels under a cold moon, you can gradually create more habitable terrain without having to finish an entire planetary biosphere. [Answer] **I think you need to make it a two stage process;** This is because you state in your original scenario that '*the planet has not developed any life at all*'. And this is key problem because it means there will be little if any free oxygen in the atmosphere and no **Oxygen Cycle**. Without some form of pre-existing photosynthesis or a similar chemical process releasing oxygen into the atmosphere constantly any free oxygen in the primeval atmosphere will have very early been oxidized and bound into the crust. That being the case. **Step one;** An automated probe is sent ahead of the colonists (or perhaps the one that found the planet originally can do this). The probe carries a payload consisting of a wide spectrum of algae species selected and/or engineered for specific sub environments (marine, fresh water, soil/rock, alkaline, volcanic arctic/tropical etc . In short the full range of environments where algae thrives on Earth today. It also carries a range of nitrogen fixing bacteria and simple plants and communal algae for follow up drops. The probe then seeds the planet, matching 'drop' locations with those species best suited to surviving in that local environment. After that it just sits back and sends back regualr reports on oxygen levels in the atmosphere and later seeds the local regolith with nitrogen fixing bacteria and plants. **Step two;** Your scientists/colonists are sent once oxygen levels start to reach something approaching breathable levels and can then start planning/constructing proper biomes using species they bring with them. How long between Step 1 and Step 2? I have no idea, perhaps an expert could tell you but I suspect it would be surprisingly rapid. ]
[Question] [ So I've finally found something that has brought me to this rabbit hole of worldbuilding. I've been doing some future planning for an expansive subterranean facility that would require heavy cargo transport and have been looking at options for such. One of the concepts I'm considering is a large crane system from a ground-level intake point that could then lower down the cargo via cable/crane/gantry winch to whatever depth it is going. Then I began wondering about what other utility could be had from such a shaft and recalled this: [![Yamatau Helical Elvator](https://i.stack.imgur.com/gtTeU.jpg)](https://i.stack.imgur.com/gtTeU.jpg) [![D6 Helical Elevator](https://i.stack.imgur.com/NqBxR.jpg)](https://i.stack.imgur.com/NqBxR.jpg) In practice, this shaft would be a secure area with the area around it being for movement of authorized personal so it isn't a thoroughfare. Setting aside the security risk that a shaft like this could prevent in the event of an incursion into the facility, and the difficulty of locking down sections of the facility if need be, how well would this sort of system work? Operating on the assumption that security issues are not an issue or have been seen to, how practical would this be? [Answer] **Ladders/vertical elevators** * Smallest footprint * Shortest travel distance * But requires you to produce enough force to directly lift your own weight (if you don't use a counterbalance). **Stairs/Escalators** * Basically just ramps * Larger footprint than a ladder * But less force required, at the expense of longer travel distance **Spiral stairs/elevator** * Just a ramp wound up onto itself to cram more length into a smaller footprint * More length means you have a shallower slope for the same vertical distance which means less force required at the expense of even longer traven distance. So good for very heavy loads or if you have limited propulsion and when you cant'use a counter balance. [Answer] You might want to glance at the spiral railroad tunnel at Kicking horse Pass in Canada. [writeup here](https://www.pc.gc.ca/en/pn-np/bc/yoho/culture/kickinghorse/visit/spirale-spiral) Of course this is about a mile diameter, which is much larger than your shaft, but that's because of the size of a train and its inability to get around a very tight curve. [Answer] An important consideration is how are you going to actually move the elevator? The spiral rail tunnels mentioned are effectively self-powered - the train provides the motive force. Elevators on Earth are generally straight, because the carriage is moved by an external power force through cables, and cables like to be straight. The Eiffel Tower has non-straight elevator shafts, and there was significant engineering effort that went into making them work. A spiral elevator is going to pose difficulties for the traditional cable system, but maybe you could have two of the rails be powered, and have a motor on the car? It will be heavier than a normal elevator, and have less cargo capacity for the same amount of power usage. [Answer] **Gearbox train cars:** My son used to have a certain brand of toy trains that used gearbox arrangements to allow the self-propelled trains to climb slopes. The wheels were there just to hold up weight. Your system could have a track with threads so the cars could grab ahold and climb the sides of the shaft. There could be a slot in the side of the wall to hold it in place, or there could be a central shaft that the cars are tethered to. Similarly, a central shaft could be threaded and either used to mesh with a vehicle's gearbox, OR the central shaft could rotate, pushing your car up and down a spiral ramp in your shaft. I'm not making any claims to what is more efficient, but this could work. If your goal is to have a spiral track going up a shaft, because it looks super-cool for your world, than it is an alternative. [![Geotrax tracks](https://i.stack.imgur.com/IjVEB.png)](https://i.stack.imgur.com/IjVEB.png) [Answer] FYI, there is a real-world, operational helical-track hydraulic elevator at the auditorium at Apple's headquarters. It rotates 171 degrees to allow entry and exit via the same door, despite the door opening on the floors being in different places. The architects claim it's the first in the world. [1](https://www.eocengineers.com/en/projects/steve-jobs-theater-293), [2](https://www.fosterandpartners.com/news/archive/2017/09/the-steve-jobs-theater-at-apple-park/) As for incline elevators, they're more common, since they can still be implemented using counterweights on tracks. The main train station here in Zurich has some. ]
[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 3 years ago. [Improve this question](/posts/182864/edit) My story happens in the same settings as my previous questions: * [Would a trained falcon be useful as a scout?](https://worldbuilding.stackexchange.com/questions/180605/would-a-trained-falcon-be-useful-as-a-scout) * [Are the draw weights of 90# to 100# realistic for women archers?](https://worldbuilding.stackexchange.com/questions/181472/are-the-draw-weights-of-90-to-100-realistic-for-women-archers) There's a tribe as in [proto-state](https://en.wikipedia.org/wiki/Proto-state) which lives mostly in a valley west of a mountain pass, while small minority lives east of it in the steppe. Their enemies, the highland clans unite under a single leader and cut off the crossing. [Composite bows](https://en.wikipedia.org/wiki/Composite_bow), trained falcons and warhorses of highest quality came from the clan which is cut off. Now the warriors are forced to do with inferior war materials. While composite bows could be replaced with somewhat weaker short bows & recurved short bows, and trained falcons are nice to have but not essential, the lack of warhorses is the biggest concern. Most of the horses in the valley are [small](https://en.wikipedia.org/wiki/Fjord_horse) [strong](https://en.wikipedia.org/wiki/Icelandic_horse) animals, excellent for farm work, but quite slow and small for war. However there is a woman from the horse breeding clan, who previously married a man from the valley and brought more than a dozen horses with her. As the members of her clan are known as superior horse breeders and masters of the bow. Is it realistic for a chieftain to conscript her to breed & train horses for them? Something like, will give you meadows, mares, and release your husband & and people that work for you from the militia duty, but you have to breed and train horses and sell them to our warriors. [Answer] If this is the middle ages, democracy and the rule of law are probably not an issue the same way it is today. Respect for traditions and ancient rights is important, but there is some flexibility in that. * **The chieftain can offer an honor she cannot refuse.** Like offering the privilege of supplying warhorses to the most prestigious cavalry units, in exchange for relief of taxes and other duties. The rights and duties of feudal liegemen and of serfs in much of Europe *were* held to be fixed since *time immemorial*, but that was not actually true. Say the villagers owed, among other things, five days reaping the manor's grain fields, and the lord of the manor owed beer and lunch during the harvest days. Or the villagers were required to mill their grain at the lord's mill, at the customary fee. When the economy changed, and another crop replaced grain, the villagers and the lord had to *negotiate* a change of the deal. Neither side could unilaterally impose the change, *ancient rights* and all that, but in the end everybody agreed to pay a couple of shillings instead of tramping out to the dusty fields. * **Who gets the offer, anyway?** Is it the foreign woman, or is it the local-born husband? Who is *nominally* the head of the household and thus entering deals? Send the *husband* on horse-breeding duty and see if the *wife* follows or leaves him in the lurch. And if both husband and wife are balky, set the task of delivering warhorses on the entire *village*. Have the neighbours figure out how to deliver. Why, surely they know someone who knows ... [Answer] **This is a Non-Problem.** So a talented horse breeder has married into the valley clan and now lives here. The chieftain wants her to breed horses for use in warfare. My question is **what else is she doing?** other than breeding horses. This is her profession. She was breeding horses before she married and will continue to breed horses until she dies. She trades the horses with the other tribe members to get everything she needs to live. Then chieftain comes along and says "Hey breed me 100 warhorses". Lady says "How do you plan to pay for them"? Chieftain says "I am the boss give me horses." It seems the real question is much more broad (and has nothing to do with women or horses): > > Can a ruler make hard demands on his subjects? > > > I think the important factor here is how big the tribe is. If the guy was a **king** of a large country he can just make demands and back them upby sending the army around. Provided he doesn't make too many riduculous demands he doesn't have to deal with an uprising. If the country is really big it's hard for an uprising to gain enough momentum to defeat the army. But since this guy is a chieftain his tribe is likely much smaller. Since everyone knows each other the chieftain cannot make too many ridiculous demands without people talking and him losing reputation. Uprisings are much easier since the guys in your "army" are second cousins to the horse lady. If you make a ridiculous demand and try to send them over over they might just refuse and join her side. One big factor that will influence how **reasonable** the demands are is **Do we actually need that many warhorses?** In times of peace a sudden demand for 100 horses will seem ridiculous. On the other hand if we were just attacked by a new enemy then a demand for warhorses seems more reasonable and the tribe will probably support forcing the lady to breed horses for free. [Answer] Warhorses were like tanks & airplanes of the modern era. Chinese send a whole army to acquire quality horses in [War of heavenly horse](https://en.m.wikipedia.org/wiki/War_of_the_Heavenly_Horses). Beside all the talk about phalanx, it was the horsemanship of the Thesalian, Theban and companion cavalry that decided battles, unless the terrain was unsuitable for cavalry (broken, not enough place to maneuver etc). Roman aristocrats served as cavalry and they hired Celtic cavalry to expand their ranks. During the crusades templars required knights to bring their mounts or a lot of money to buy those, otherwise they were sent back. The major problem for crusader cavalry was to keep themselves mounted. The advantage of the cavalry is their mobility, which allows them to choose where and when to fight. If her super horses gives them that advantage they would want them. If she want to sell them abroad they could ban export of war horses. The thing that worries me is that they live in the valley, while her clan is in the steppe. The steppe means sea of grassland unsuitable for agriculture, great for pastoralists. Valley on the other hand means plenty of fertile land, excellent for agriculture, too expensive to be wasted on pasture. Chinese tried many times to breed their own [horses](https://www.medievalists.net/2020/06/horses-medieval-china/), even imposing quotas of something like horse per 10 families but farmers resented it and the results were poor. Horse is uneconomical compared to water buffalo to the settled peasant. So even if your woman wants to help the war effort, and the chieftain gives all the meadows, the horses will still remain something reserved for the rich, few and expensive. Settled peasants land are not suitable for large scale horse breeding. ]
[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/178064/edit). Closed 3 years ago. [Improve this question](/posts/178064/edit) What if people could fire magical energy beams from their hands. It requires no external resources and is easy to use and cheap. The magic attack has three characteristics : 1- Phases through any form of inorganic matter, only interacting with living things. 2- Secondly it is concussive in nature, and is never lethal. 3 - It shocks, stun and locks it's victim into place for few minutes [Answer] Inferences: * Fighting ability is less important, since the easiest way to win a fight is to deliver the stun and then finish. But tactical training, agility in the battlefield would be precious. * melee soldier units are less valuable than projectile units Therefore the shield units should form a line an protect the projectile (bows, crossbows, siege weapons) weapons. * Heavy armor is less useful. A normal shield would be better suited to defend against arrows. * So, shield formations are very useful. Think romans or vikings. * Shields could be disguised as special shields. Even if detection is possible maybe little bits of materials could allow to trick detection. * Cavalry would be succeptible to lines of riflemen so used after the first shock or for surprise movements like in napoleonic era. * Long lines of cavalry armed with pistols or rifles would be suited to spear enemy lines If they are not shot. They could shock and then hit with the other side of the weapon as a mace. But maybe it will be better to attack with spears/flails and keep the magic shot for later. Riders could hide behind their horses to dodge the shots. They could be equipped as napoleonic grenadiers but with a shield. * A shielded horse with a shielded rider would be a special weapon to break enemy lines, route archers, create disorder. A little special unit like this could cause a great impact if able to flank enemy lines. * The default strategy is attack not defense: stun and charge, stun and shoot. If you stay put the enemy will do this. * Another tactic is to dive and stun from a prone position then a second line of infantry men coordinatly charge. * As above but the second line throws javelines/pilum and changes to rifle. Then another line behind and so on. The idea is to switch lines as much as possible since they have "magic park" * Obvious manoever: to block one side of the battlefield with several lines of riflemen and use the offensive tactis above with the better troops in the other side (or in both flanks). * Alternatively one row of riflemen can work together with a line of archers. One stuns the other finishes with a volley, then maybe the archers dive, change weapons, stun the front enemy line and finally infantry charges, stuns then shocks. In general it looks like napoleonic era tactics with prone position like in Civil War and a touch of viking skirmishes. [Answer] Even a brief advantage is an advantage. In pre-Revolution America, rifles were often used to fire one volley to frighten and injure the enemy. Then the attackers dropped them and charged with hand weapons. If you can distract, immobilize, or stun your opponents, you'll be able to control the battle. Even if you can shoot your weapon at just 10% of the enemy, you'll be able to win a battle, all other things being equal. Another advantage would be targeted killing. It sounds like you could gather several soldiers together and target well protected enemies. If your world uses traditional combat tactics, the enemy commanders might be within sight (albeit out of arrow range). Bring able to kill them early in the battle could make for a short war. [Answer] this can be devastating to formation especially to cavalry. so to counter this thing i believe they will use literal meat shield like napoleon era, or like strapping light animal inside of the shield or put them as meat armor, at least light enough to be able to lift easily for a person and not aggressive, since OP say life Horse also get affected, (i reconsider to put them covered inside the shield to make sure the chance for it to still "alive" to counter the magic, definitely will be strapped shield type and quite conical or curved to fit the animal in it or a pavise kind of shield, if want to put them inside the shield, if the person cant withstand tickles or something wriggling on their main body) considering the anti magic shield is expensive, and i believe it is better quality or not as awkward compare to strapping animal inside it, probably only affordable or best suited for the commander or general and the front line of cavalry in wedge formation without losing momentum or crash with their front line (depend on the size of the magic shield or the protective range of the anti magic, since i just found out horse get affected, but cavalry is more likely become obsolete otherwise, since horse is scaredy cat, and i am not sure strapping small animals as armor can work or worth it). or it will be guerrilla warfare or like modern warfare considering everyone can use this magic. i agree with Tomas, shield at least will be given to all the unit to deceive their opponent. regarding fortress siege or defense it depend on the strategy or tactic, since both can use it. and the wall is good enough to hide you from getting targeted. after seeing the edit that it include firearm or explosive weapon, then i believe guerilla warfare or modern warfare or at least trench coat warfare is more likely to developed, even napoleon kind of formation will be devastated in this case, and armor definitely obsolete (excluding modern armor if OP has it), since firearms will dominated more, though it still depend on OP anti magic shield and normal shield, but i am skeptical napoleon type of formation is worth it in this case. [Answer] The most obvious answer would be to break lines; stopping a cavalry charge or breaking a shield wall, for example. Since it seems that just about anyone can use this magical beam, you can have a large number of levy soldiers use the beam to stun charging horses, knock over heavily armored shieldbearers, and the like. In an open conflict, it would be useful before melee begins to disrupt the opponent. Of course, open conflicts were uncommon. In a siege, you could fire these beams through the walls to get at pesky archers through murder holes, blast a particularly powerful and long-ranged shot at the general outside of your city, or send a couple assassins in the city to go outside the palace and aim the lethal beam directly into the throne room. [Answer] In war there are many important rules. The most relevant for this question: 1: people usually dont want to die. 2: people usually dont want to kill. Both historically and currently fights take hours, often with relatively few casualties considering you have a few hundred to a few thousand guys with weapons swinging or shooting at ranges where either one dying should be almost a given. In fact I think it was miss nightingale that use statistics to prove how important hygiene was on and off the battlefield as the casualties from infection dwarfed the actual deaths during combat. During the Vietnam War this was finally investigated in full, showing how much the soldiers would use the "look busy" tactic and would fire several meters above the enemy or not in their direction at all. Although even during napoleonic times this behaviour was somewhat known, as they lined up a battallion and had it fire at a sheet representing an enemy line to count hits per volley to get an idea of accuracy. Only to find out that for each volley only a handful of people (if that) got hit during an actual battle. In comes your magic, people would absolutely love this. In swinging-weapons times people would use this to knock out enemies and disarm them. You dont have to kill them if they are dazed and confuzed right? And capturing you might get a ransom (or your liege lord would get one). It works similar to how you treat prisoners actually: if you kill or mistreat your prisoners the opponents will fight you much more to the last as they dont want to die. But if your opponents see and hear their fellows being treated fairly and kept alive then suddenly surrendering sounds like a novel idea. So if you dont kill knocked-out enemies, your opponents are less likely to kill you if you are knocked out. On top of that everyone will be enthousiastic about trying to capture their enemies as they dont have to kill and they reduce the risk of their own death with each disarm/knock-out. Since its still a dangerous thing and people will still die it will also mean that more soldiers might fake being hit and unconscious, as you are less likely to get stabbed or shot when you go down. In shootie-shootie era's a similar thing will happen, only with higher casualties. When you've knocked out half a squad you often dont know how many you've knocked out and how many are still firing back. So capruring is going to be tough and dangerous. But you dont have to directly kill them either as just like modern combat you will pin down and suppress the enemy and then call in an air/artillery strike to kill your opponents. Since its easier to knock out and freeze enemies in place (and now armored tanks can be stopped by any infantryman or even an unarmed civilian!) It will be a high price indeed for lives. On the other hand here the "look busy" and "keep myself alive" pops up again: when someone is wounded or knocked out, you bring them (and incidentally yourself) to safety right? Even 10 minutes off the frontline before going back is better than being stuck at the frontline. This is what already happens currently, sometimes with 4 or 5 mine carrying a single lightly wounded soldier. And unless special doctrines are created to check and recover unconscious people at the frontline you will have a lot of fights be determined by who can get the enemy to be busy with dragging their own men off the frontline.. Weapons development wouldnt change much, or small arms at least wouldnt change much. Tanks would naturally get those shields build into their armor at various points. You will always want to give your men a superior weapon even if they can knock people out. However trying to outnumber your opponent and hitting a room from every angle would be a common tactic. ]
[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. Due to reasons of magic an alien god that is about to takeover the earth in one year and can only be stopped by being shot through the entire earth. Assuming modern day Earth (no magic other then that protecting said alien god from all other forms of damage) and having the entire arsenal of mankind is it possible to shoot said alien god through the entire diameter of the Earth? This can be done via nuclear bombs directing a shaped charge (sorta like an RPG on a massive scale) to bore through the planet, via blowing up a tunnel in some fashion a millisecond before a bullet pass through the open tunnel before it collapses or via any other means\combination, the only thing that's important is that the "bullet" (however shape or form it will be) will be shot down towards the Earth at one side of the planet and will pass through the entire Earth before going out the other end. **Hard sci question, I want to see the math involved** [Answer] I don't think it is possible. Newton calculated that the [impact depth of a projectile is roughly equal to its length](https://en.wikipedia.org/wiki/Impact_depth). > > The impactor carries a given momentum. To stop the impactor, this momentum must be transferred onto another mass. Since the impactor's velocity is so high that cohesion within the target material can be neglected, the momentum can only be transferred to the material (mass) directly in front of the impactor, which will be pushed at the impactor's speed. If the impactor has pushed a mass equal to its own mass at this speed, its whole momentum has been transferred to the mass in front of it and the impactor will be stopped. For a cylindrical impactor, by the time it stops, it will have penetrated to a depth that is equal to its own length times its relative density with respect to the target material. > > > This would mean that, to penetrate across Earth, the impactor would need to be as long as Earth diameter, that is about 12750 km. Such projectile is likely impossible to hold stable, since it would collapse under its own gravity. [Answer] It is well beyond impossible, if you assume the alien god has mass. If you do something clever like positing the alien god is made up neutrinos, as one comment pointed out (mass not the issue with them), then it's pretty easy to get 99.99999999% of it sent thru the Earth. However, your desire for "hard science" in the face of a supernatural alien is simply not possible if you want your readers to accept your overall story. Clearly it's 'magic' that somehow kills the alien god on his trip thru the planet, since merely accelerating him to a similar speed elsewhere doesn't kill him -- according to your scenario. The only way out of that contradiction is to calculate that something else, e.g., magnetic field interactions, are what kill it. Then you can skip the whole "we had to destroy the earth in order to save it" cliche. [Answer] Broadly speaking, a hypersonic penetrator, and which is moving faster than the speed of sound in the material it is made of, will penetrate roughly to its own length. So, if you have a penetrator more than 8,000 miles long - which would need to have a reasonable width -- and fire it at a few miles per second, you might get somewhere. Best might be to use a segmented penetrator, essentially digging your way through in a series of steps. This would be vastly bigger than anything we can conceive of producing with any existing EFP or shaped charge technology. It is many, many orders of magnitude than the 'biggest shaped charge ever' I wrote about here -- <https://www.popularmechanics.com/military/research/a23740/bunker-buster/> [Answer] # Maybe, if you hit the Earth with a Mars-sized projectile According to the [giant-impact hypothesis](https://en.wikipedia.org/wiki/Giant-impact_hypothesis), a long long time ago a planet roughly the size of Mars struck the Earth. The resulting debris formed our Moon. [![Visualization of the giant-impact hypothesis](https://i.stack.imgur.com/od8hn.jpg)](https://i.stack.imgur.com/od8hn.jpg) It's unclear from your question if you want to have a precise sniper-like shot that penetrates the planet or if you'll accept a... messier... approach. A large enough object hitting the Earth at a high enough speed could eject debris from the far side of the planet and into your bad guy. The penetrating planet wouldn't necessarily go all the way through the Earth, but it wouldn't need to. [![Diagram showing four stages of the impact and the Moon's formation](https://i.stack.imgur.com/njJZD.png)](https://i.stack.imgur.com/njJZD.png) So much debris would be ejected from the impact that your baddie would be hit no matter how far the planet penetrated. The real challenge here is controlling a planet-sized projectile, but I leave that up to your imagination. [Answer] Given the realities of impact depths, you're going to need something with a LOT more bang than any conventional or unconventional weapon remotely feasible. Andrew Brezca suggested smacking the earth with a moonlet, I think that's not quite enough. You'll definitely destroy everything on the earth's surface, and the earthquakes it'd produce would be impressive. But for physically clocking a god with a piece of hypervelocity moonlet? Not so effective. moonlets will splash rather than overpenetrate. What you need is a rogue extra-solar moon impacting exactly the opposite side of the planet at a modest fraction of the speed of light. [![enter image description here](https://i.stack.imgur.com/2kVS2.jpg)](https://i.stack.imgur.com/2kVS2.jpg) That'll do the job! The problems are twofold. First, you *will* kill everything and everyone on the planet. Second, the odds of it happening are nigh zero, comparable to shooting someone with a gun and the bullet being vapourised by lightning before it gets to its target. It'd take..dare I say it, an act of god. [Answer] **Maybe by using artificial micro-black hole as a bullet?** *Benefits as an extreme high energy directed weapon, that avoids problems such as Newtonian momentum transfer relation to width of the low momentum projectile, relating it to superior density and quantum mechanical phenomena instead, both of which were enough on their own to avoid usual Earth-penetrating energy scattering problems without destroying Earth in the process. Brief explanation:* If you had enough time and resources, you could build a megastructure of hollow, nearly perfectly spherical shape in space and remove pretty much every atom inside the sphere to get it in as close to perfect vacuum as superhumanly possible. Then position the sphere and other related structures to the opposite side of Earth than what is visible to the godlike creature. You could harness energy through massive array of solar-PV:s, capable to turn significant portion of whole radiative output of the Sun for quite some time in the form of antimatter. Drain the Earths oceans from deuterium for fusion reactors to produce incomprehensible amounts of energy. Maybe add microwave laser receivers from other reactor sites on planets/moons using fusionable energy sources of other celestial bodies. Then, you would need something called "nuclear lasers", nominated by the authors of the study speculating feasibility of "Black Hole Starships". I will add a link to arxiv library at the end of this message. It allows you to download the original study supported by some hard calculations in .pdf. Those nuclear lasers would need to be capable to produce extremely high power and short burst of gamma ray lasers that can be very precisely aimed. When you had collected energy storage with a mass equivalence of a few hundred thousand tons and capability to release it within "a-time-unit-of-extreme-short-lenght" with perfect simultaneous timing, aimed at the center of the hollow sphere from the inside walls, the gamma photons would meet at the center of the sphere in the focal point on top of each other at the same time. Since photons are bosons, they are not restricted by Pauli exclusion principle like fermions, ie. quarks, leptons: stuff we like to think as "matter". This would eliminate all the repulsive forces involved in black hole formation normally observed in gravitationally collapsing degenerate matter, when fermions use pretty much all the tools in their arsenal to avoid occupying the same place with identical quantum states, which makes it extremely difficult to create artificial black hole from matter. Instead, when approaching the collective focal point, the photons would create a contracting ball surface, and the collective sum of mass-energy of those photons would start to form a gravity well, or a more like a "volume reducing spherical surface 3-d gravity trench", with the deeper the trench the closer the photons get to the focal point. This gravity trench would further blue shift the photons to even faster frequency, contracting the wave lenght thus increasing their energy from released gravitational potential energy relative to each other, just like when core of any massive object collapse in to a smaller volume and it heats up. If the focal point size, sufficiently small wavelength to fit inside that volume, and combined energy of photons within that region exceeded the Schwarzschild radius of given energy, then instead of going through each other and continuing to hit the opposite wall like normally would happen in the case of photons, the space-time curvature in that extremely small focal point volume would be high enough to form an event horizon that traps the photons. You would then have created a "Kugelblitz", a microscopic black hole made entirely of light rather than matter, in the center of the now exploded sphere. That micro-BH would, -because of it's very small surface area- radiate Hawking radiation with the power output relatable to powerful nuclear explosion every second, power output only increasing when it would get smaller, until completely vaporized (which would take hundreds of years). Such a small black holes are theorized to be "anorectic" in a sense that they would probably not swallow almost anything even if placed inside a very dense stellar remnant, bacuse micro-BH:s extremely small cross-sectional probability to hit enough elementary particles to have any practical effect on their mass and momentum. It would only follow its free-fall geodesic and orbital trajectories without "noticing" if there even was some matter nearby, only affected by idealized gravity. This small point-like object would have a event horizon diameter in an order of magnitude thousands of time smaller than a single proton. micro-BH, or Kugelblitz, emitting extremely intense gamma radiation and creating sphere of aggressive pair formation of particle-antiparticle pairs around it would more likely explosively ionize everything from it's path inside a planet or a star, rather than actually touch or swallow any of it. If that "glowing micro-hole" had such a velocity that after it penetrated Earth and emerged to surface from the other side would still exceed escape-velocity of the Earth, then you would have an all-penetrating continuous nuclear explosion vaporizing a not-too-large to cause apocalypse -sized cavity in front of it rising from the ground, through the godlike thingy, and shoot straight up to the sky without ever returning. Cavity behind it would probably just be re-filled by surrounding pressure fast, and Earth wouldn't have much, if any, serious damage from the event.. (at least in severity comparable to the picture above of hypervelocity kinetic impactor..). It would be the matter of plate tectonics and position of the godthingy relative to them what would be expected to happen to Earth destruction wise. Maybe the BH would pop from the ground with a fountain of molten magma behind it, cause earthquakes, tsunamis and possibly increase volcanic activity, but probably not anything too serious to wipe out humanity let alone all life. Links: <https://en.wikipedia.org/wiki/Kugelblitz_(astrophysics)> <https://arxiv.org/abs/0908.1803> ]
[Question] [ I am currently trying to write a story about a World War 3, but the major issue I am having is the presence of nuclear weapons. I want the war to constantly escalate to a point where it becomes a total war to setup a future story/idea I have in mind. However, the threat of nuclear weapons (mainly ICBMs and those from SSBNs) poses an insurmountable obstacle for me as of now. I am trying to figure out a military way for nukes to no longer be a factor in this war, rather that they somehow be destroyed by the major powers in the war. I was thinking about something like rail guns to target ICBMs before they reach the upper atmosphere but it wouldn't be foolproof, nor would it solve the SSBN problem. **EDIT**: The timeline is near-future: basically technology is advanced enough for us to reliably send missions to Mars and have warfare in space with purpose-built ships designed for combat. So around 2060-75ish. Space warfare will be in its infancy, the best way I would describe it is like when ships finally got fitted with cannons in them by design. Likewise, this time we are seeing the very first purpose-built space weapons. My initial idea was that something like [Philedelphia Station](https://cnc.fandom.com/wiki/GDSS_Philadelphia) from Command and Conquer along with some sort of satellite defense network would render ICBMs useless, but then I realized the number of nuclear weapons would make that untenable, and would potentially be vulnerable to being itself taken out by a space weapon. **How can I make the current delivery of nuclear weapons obsolete?** [Answer] You haven't specified how far in the future you're thinking, so let's go with some Technology Indistinguishable from Magic: # The Neutron Limiting Field (aka FissionBGone) Doctor Halle Toesis was working in her high-energy physics lab when she determined that running electricity through an antenna of exactly 14.2 HU (Halle Units) length, cycling at 14.29 GHz, caused neutrons moving at more than 100 kEV to spontaneously emit visible-spectrum photons and lose the corresponding amount of kinetic energy. This caused the U-235 sample she was working on to start glowing like a lamp, but, crucially, stopped its fission altogether. Being no dummy, Dr. Toesis immediately contacted Lockheed Martin - while sending her results to be publishled publicly in one year, thus securing both her financial future and the future of the planet. By creating large Neutron Limiting Fields, cities became proof from any sort of strategic nuclear strike, as no nuclear bomb could detonate once within it. Careful exclusion areas were developed for nuclear research and power generation, but in a decade, overlapping fields covered most of the populated area of the planet. Wars, therefore, were restricted to old fashioned guns and bombs, with the hideous city-destroying nuclear weapons replaced by hideous, city-destroying ultra-accelerants and chemical weapons. [Answer] Since ideas like SDI and similar have already been floated, I’ll offer two ideas that are on the wild side. NUMBER 1; The proliferation of particle beam weapons means that a nation's own nuclear weapons can be detonated prematurely, even over their own territory. The particle beam weapons saturate a non-critical mass of fissile material with slow-moving neutrons triggering a chain reaction. The detonation is a fizzle, which is still pretty destructive and spreads highly radioactive material across the area of effect. NUMBER 2: Wakanda sez it will remain neutral in any conflict until nuclear weapons are used. Then, and only then, will Wakanda take action and declare unrestricted war against the country or alliance that used nuclear weapons against other humans. And, of course, I don’t mean Wakanda in the sense of the Marvel Universe, but am using it as a stand in for a highly advanced and powerful nation like [Freedonia](https://m.youtube.com/watch?v=Dsw9jYU_rJI) for instance. A nation so powerful that no other country or alliance of countries would ever consider entering into hostilities with it. They are wise enough to know if they try to enforce a global peace, that the results will be disastrous so instead they try to limit the carnage of the less advanced nations. Hoping that in the future, all nations will chose to live in peace. [Answer] The idea of satellite defenses to render nukes useless is a good idea. And not a new one. **Strategic Defense Initiative Redux.** **1983.** > > It was a plan that read like science fiction: A system armed with an > array of space-based X-ray lasers would detect and deflect any nukes > headed toward the United States. President Ronald Reagan saw the > proposed Strategic Defense Initiative (SDI) as a safeguard against the > most terrifying Cold War > outcome—nuclear annihilation. When Reagan first announced SDI on March > 23, 1983, he called upon the U.S. scientists who “gave us nuclear > weapons to turn their great talents to the cause of mankind and world > peace: to give us the means of rendering these nuclear weapons > impotent and obsolete.” > <https://www.history.com/news/reagan-star-wars-sdi-missile-defense> > > > **2024**. Rogue elements in the North Korean military launch intercontinental ballistic missiles with various warheads; these reach South Korea, Japan, and (accidentally) China and North Korea. In the aftermath, developed nations of the world reboot SDI, arming space in such a way as to prevent the use of long range missiles of any sort. The developed countries realize that these weapons can too easily fall into the hands of actors with nothing to lose and so the only way to prevent wanton destruction is to deny them to everyone. The signatory countries go about dismantling most of their own now useless nuclear missiles. [Answer] A completely different direction of thought: Maybe in that future, nuclear power was utilized so widely and intensively that all uranium has already been used up. Since the world had gone through a peaceful phase, this also included any uranium originally used for nuclear bombs, as well as any plutonium that could be generated (for a while, plutonium power plants were used to replace the uranium plants running out of fuel). There are no nukes, for lack of fissile material. Since it was finally figured out how to build viable nuclear fusion plants just when the last stocks of fissile materials got used up, this did not lead to an energy crisis. But when hostility returned to the world, nobody could figure out how to detonate a thermonuclear bomb without a fission starter. [Answer] Have someone discover an incredible medical process which so supercharges the human immune system that within its' recipient, all existing medical conditions are cured and estimated youthful life expectancy is increased by 50 years. The only downside is that the process consumes a not-insignificant quantity of weapons grade fissionable material. Within a few decades of this process becoming available, all the nuclear refineries will be re-purposed from military to medical usage, and every single ICBM's payload will have been stolen by the very officers assigned to guard them. [Answer] **It already exists** It's called "Mutually Assured Destruction". If a country uses nukes then every country with nukes will use them back. You can't make nukes redundant unless you replace them with something better which doesn't help you. Even if you invent a system that can shoot down ICBMs before they hit orbit, nukes can be send by drone, submarine, ship, shipping container, planes etc. Heck, governments could smuggle them into countries via embassies during peace time so they are already in place before a war breaks out. The only thing that stops nukes from being used is the fear of them being used against you [Answer] **Cheap antirocket system.** Right now we're destroying them with many times more expensive rockets, so the game favours attackers. You need a situation when it works in the opposite way and ex. laser armed satellites or railguns are much cheaper than their targets. (at least per shot) However, such weapon would also slaughter all aircrafts and railguns would be tremendous artillery. **Conventions** In case of multiple powers, some 3rd party may dislike nuclear fallout on its soil and openly threaten with bloody revenge anyone who dare to use nukes. As long as they are not bluffing and clearly able to tip the balance, then ignoring them would be a bad idea. **Still a limited conflict** Soviets, in their famous war plan [Seven days to river Rhine](https://en.wikipedia.org/wiki/Seven_Days_to_the_River_Rhine) planned not to use nukes first and even when tactical nukes were used, to try to avoid to use them against targets on soil of nuclear powers like France or Great Britain. (Yes, Russians were willing to nuke even Italians and Danes, but hoped that conflict would not escalate so much that Soviet Union would be targeted too. Presumably there is gulag for people who doubt that it would work ;) ) [Answer] TL,DR: Keep the current expensiveness of anti-nuclear options like THAAD or I-5 interceptors (or knock some off the price but not too much) and create an IAEA on steroids that regulates nukes, economical sanctions and liberally invests and distributes a large range of anti-nuclear options to countries to reduce the success chance and cost/benefit of having a nuclear arsenal in the first place. Long version: Intercepting ballistic missiles is expensive, an interceptor missile that tries to take out a minuteman III during its boost phase is in fact larger and more complex than the ICBM it tries to catch up to, which considering the speeds of ICBM's and the time it takes before you can fire an interceptor (often more than half a minute) isnt that surprising. So rather than invent new ways of stopping ICBM's you could create incentives not to have nukes in the first place. So what if the world simply funds an anti-nuclear organisation who's sole intention is to prevent large scale war by any means necessary? Basically it would be the IAEA but on steroids. Using political pressure, agreements with possible massive economical sanctions and a worldwide expensive anti-ballistic missile system (ABMS) combined with a large arsenal of cruise missiles and the like intended to damage and disable nuclear launch sites.. Countries surrounding nuclear superpowers are going to be dealing with the most unintended consequences of a nuclear war (aside from those living in the bombed country), and will agree to an ABMS far sooner. If you and surrounding countries can guarantee missiles of the nearby superpower to be shot down or prevented from firing then retaliation isn't a necessity. The downside is that it also makes you a target by the superpower in question. So as another consequence this organization will demand that all countries disclose the position of all their nuclear silo's and firing positions. Anyone who is found out to hold secret sites will automatically receive massive economic sanctions with the goal of hurting their economic capability to sustain nuclear weapons along with a civilian populace that will protest nuclear weapons to rid themselves of the sanctions. Additionally anyone who seems to prepare strikes to disable the ABMS and have tried to keep launch sites secret will be retaliated against by the combined countries with the goal of disabling the nuclear weapons. Yes there are countries like Iran that arent deterred by this but in this case the steroids IAEA would expend massive amounts of missiles and perhaps force a coalition invasion to stop it if a threat continues. Faced with this, many countries would refocus their military spending on other weapons. Why spend billions researching, building and sustaining an ICBM arsenal if you are faced with harsh economical sanctions, possible invasions, your nuclear sites bombed and any missile you did fire having a massive chance of being shot down anyway? For "theater" nuclear warheads and tactical nukes the organization would use widespread THAAD launchers and similar systems. They are too expensive to use against aircraft and would you use them against a fighter if you knew nuclear strikes could still happen? [Answer] Given the number of possible delivery systems for nuclear weapons, as well as the proliferation of the weapons as well as the knowhow on how to make them, I'm afraid any technological or political means to prevent their use is doomed from the start. Even were you to have a world spanning ABM defense in place, that's not going to stop cruise missiles, artillery shells, torpedoes, freefall bombs from aircraft, or a truck or cargo ship driving into a city under a false flag loaded with a nuclear weapon on a suicide mission. All those methods have been fielded or at the very least postulated as delivery systems, and are quite viable. Heck, there were even experiments with nuclear hand grenades (never fielded as it was found the strongest soldier couldn't lob them further than the blast radius) and bazookas (which were actually fielded, despite the same problem in all but the most perfect conditions). So you're not going to have a technological means to stop nuclear weapons from being successfully used. Given the relative ease of designing and building them (the problem is mostly getting the raw materials, not turning them into a bomb, even if a crude one) you're also not going to be able to have say the UN simply ban them and nobody will have them any longer, especially if this turns into an all out war of survival for the countries involved. At least one and probably several WILL start building them and using them if the situation gets dire enough for them. Think the current Israeli stance where their nuclear arsenal is a weapon of last resort, to be used only if nothing else can prevent the destruction of the country they're going to take their enemies with them. So politics is also out of the question. And in a war the scale of WW2 or larger, with the very existence of countries in questions, entire peoples being threatened with annihillation, moral objections are also going to take a back seat over the will to survive. So even the most steadfast pacifist will eventually have to face the question of whether they'd rather die or live with the consequences of using a nuclear weapon to destroy those attacking them. So no, unless you have some handwaivium going on here that makes nuclear weapons impossible you're not going to prevent their use. The cat is out of the bag and has been since the 1930s (it was known as far back as that that nuclear weapons were theoretically possible, though it took until about 1943 to figure out how to actually construct them and even then there were surprises, like the impossibility of the gun type plutonium bomb, which came as a surprise only found out during the design and component testing of such a device). And once that happens, it's next to impossible to prevent a system from actually being built if the stakes are high enough to warrant it. [Answer] ## Neutrino "laser" There have been claims that [even solar neutrinos](https://science.slashdot.org/story/10/08/26/1749232/Follow-Up-On-Solar-Neutrinos-and-Radioactive-Decay) might alter the decay rate of radioactive elements. These are highly unlikely, but they illustrate the leeway you have to work with. Given a device that can produce a powerful collimated beam of neutrinos - many more of them in that beam than are found in the Sun - you can shoot them all the way through the Earth and nothing can stop them. Neutrinos participate in many nuclear reactions. So this means you can simply target the enemy's nukes (especially assuming your neutrino detection capabilities are equally well evolved, since they give off a neutrino signature). Change their decay rate - overheat them if you are feeling nice, and if not ... The enemy would hasten to dismantle their nuclear capabilities. It is possible that they could try to have a few devices they could rapidly assemble before use, but they would be up against the risk that you could enhance the power of your neutrino beaming array until those pieces could also explode. [Answer] Almost all countries participating in WW2 had significant stock of toxic gases and the weapons capable of delivering those to the battlefield. Yet, no one used them to any significant degree, not even in the event of total loss. Poland in 1939? No. France, Belgium, Holland in 1940? No. Soviets in 1941? No. Germany 1944-45? No. In fact the only major use of toxic gas at that time outside WW1 was in asymmetric warfare - Italians used it during invasion of Ethiopia. Everybody knew the other side has such weapons as well and there will be no victory in using them as enemy will respond with the same and nothing will change while the civilians will suffer immensely. It is possible that if two nuke capable powers ever go to war, they will react the same - threaten the use of nukes, but never actually use them. The main problem may be if the powers are not bordering eachother, as any use of heavy bombers or ICBMs is a risk of nuclear attack, so a conventional bombs carrying bombers may result in nuclear counterstrike... [Answer] Major powers stopped keeping nuclear weapons because of the infamous events of October 4th, 2052. For a period of time from about the 1990s to the mid-2050s, the biggest threat to a nation was not other nations, but terrorist groups. It was only a matter of time before a terrorist cell succeeded in pulling off the ultimate inside job: as seemingly upstanding US citizens with no criminal records or known connection to terrorists, they were able to become trusted members of the US military, and of the defense contractors who supply it, and climb up the ranks. In 2049, Complete Annihilation Systems were contracted to supply the hardware and software for an upgrade to a nuclear weapons silo somewhere in the north-eastern US. Unknown to the CEO or the US military, almost the whole team working at Complete Annihilation Systems who were responsible for the project - and the team of engineers working with them on the US military side - were secret members of the terrorist group. The system they developed had to pass inspection by higher-ups in the US military, of course, but by discovering (and keeping secret) a weakness in the cryptographic algorithm used to authenticate launch codes, the terrorist group was able to design a sufficiently-well-hidden backdoor into the system. It passed the standard inspections in May 2051 and December 2051. Their opportunity came on October 4th, 2052, when what was supposed to be a test launch ended up being nothing of the sort. In addition to killing hundreds of thousands of people in Washington D.C., it was the first assassination of a US president since 1963. The calculus was simple: when your enemy is not a nation but just a small group of (highly motivated and resourceful) terrorists, there is no possible threat of using nuclear weapons against them in retaliation, so a nation's nuclear capability does not function as a deterrent to prevent nuclear attacks against that nation. So when that nuclear capability is most likely to be used by traitors against the nation itself, it is in the interests of national security not to have such nuclear capability at all. In theory this meant foregoing the deterrent against nuclear attacks by other nations, but in practice the other nuclear superpowers saw what happened in the US and decided it would be prudent to do the same, so there was nothing to deter. (Of course, all nations kept their missile detection and interception defense systems in place, just in case, and because this was required in order for unilateral nuclear disarmament to be politically tenable.) Without nuclear deterrents, "traditional" warfare between nations became viable again. The rest is history. [Answer] I might like to add you specify only that nukes are not a factor in this war, not that they are useless or no longer function. Have you considered an environmental reason why any country detonating a nuke anywhere on the planet would have global cataclysmic consequences? You may prefer a less hand-wavium explanation which might be a topic of another question, should you choose to go down this route. But the idea that weapons of such destruction may cause an already collapsing environment to turn up the violence in natural disaster side effects and harm their allies could result in turn coating or unrecoverable political ties, not to mention general habitat and natural disaster fallout that could make living in many large areas impossible. Not to incite some kind of debate about what nukes do to the weather patterns we currently have, but perhaps the scientific data behind unstable weather patterns globally were explored when idiotic notions such as nuking a hurricane were puked out by some fool, revealing how destructive the side effects of such an act would be. And despite that warning, said insipid fool somehow manages to overturn all authorities and actually does it, which causes the extreme backlash as warned, forever ruining the stability of large regions already prone to weather disaster, causing greater storms, and so on... until many years later where these storms are a normal thing, hugely devastating, your war starts to boil up, and an act of NATO or some other convention like the Geneva one which is often ignored set upon us standards to ... disarm... or some such... nukes with recent history as a guide that shows the planet as a whole cannot sustain any further detonations. Here's where your hand-wavium comes into place. Yeah, we already have agreements of some kind, and yeah people claim they have dismantled some of the nuclear stockpile. But a lot of that could be thought of like an international policy deal that keeps economic stability in place for everyone, as well as makes what seems like a good impression on the inhabitants of the world. Never before has it become so evident that using them would bring upon the planet a global assurance of immanent death. The existence of fallout proved already that nuclear weapons leave a dent in the world none of us alive now will live to see the end of. Careless use, like what started the climate disaster era, have convinced everyone that it is clear these weapons cannot possibly be used to the end of peace. They will destroy us all if anyone uses them. And so your hand-wavium is that this unstable global condition is bad, but how bad and the precise details of all the whys and what abouts don't really get explored. Only that it is clear that use of nuclear weapons, and even the threats of nuclear disaster like Fukushima Dai-ichi eventually going full on melt down pose a threat of such significance that even in a state of war, everyone involved knows that using a nuke anywhere would be an act of suicide. Violent winds, storms, enormous shifts in conflicting temperature heat zones, and even such things like contaminated industry and global trade meaning everyone on the planet could be exposed to lethal levels of radiation simply because one nuke dispersing fallout amid a turbulent environment means everyone alive gets hit with the same bomb no matter where it is dropped. So people refuse to accept it as a viable option, even in the worst of wars. Threatening such use causes social panic, catastrophe, riots, protests, and possibly even erupts smaller civil wars. Stock markets go nuts over the impending destruction and presence of large corporations involved in global trade. Destabilization is guaranteed. It is no longer a utility to demonstrate power. Possession and use of nuclear devices is now considered a top tier threat to the existence of humanity, and the warlords of the planet know this. As a result, they have not agreed upon anything in the form of a convention. But it is just known that to use one would be ending the war for everyone with no victories. What use is winning a war if there is no planet left to live on? And thus, nukes are not a factor in you war. Simply because in your world the warlords are convinced it would mean the end of everyone, which is not anyone's goal. [Answer] A reasonable assumption is that any leaders would be unwilling to let their territory become radioactive or have their population nuked. However there are many historical conflicts where leaders only balance death and destruction to keep their position or to save their own skin and many where their own population is simply a tool for their own ambition. As you state that space flight is reasonably reliable in your future history then the logical place for leaders and their military establishment into space as a limiting factor of missiles is how they manoeuvre assuming airflow to guide their flight. Although it’s obviously possible to build space capable missiles they do not currently exist so to make space-capable missiles would in effect require a reboot of nuclear proliferation. In a reboot situation modern defences such as lasers become far more effective especially if they escalate side-by-side with space capable nukes. ]
[Question] [ I'm thinking of a predatory creature that lives deep inside large caves. Because this environment is so dark, the creature's eyes have disappeared through evolution since the creature relies on echolocation rather than sight. But the thing is that this creature has a large frill around its neck with small bioluminescent marks. But that got me thinking, what is its use? I mean, if the creature is blind then it surely can't use the frill to frighten other members of its species. So why would it evolve something like that? [Answer] Just think of that other place where the sun doesn't shine. I mean the ocean depths. The bioluminescence of a blind animal (such as a bioluminescent jellyfish) can either stun or confuse a predator that is not blind. The [atolla jellyfish](https://en.wikipedia.org/wiki/Atolla_jellyfish) in particular is a sore loser - if it gets attacked by a predator that is able to eat it, it gets flashy and its lights end up attracting even bigger predators that will eat its attacker. And the there are the angler fish. They use bioluminescence to attract prey. Granted, they are not blind. But your blind creature may use its frills to both attract and capture prey. [Answer] The bioluminescence can be a vestige of when the creature's ancestors lived in very dim caves or caves (or other spaces) that were dark part of the time while they were awake. While they still had functional eyesight. Plenty of species have biological traits that aren't currently needed. If there's no evolutionary advantage to *not* having them, they may not fade away as quickly as traits that are better off not being there (like eyes that can be a vector for infection if injured). Once you've established that the bioluminescence is still around, it can prove itself useful in the ways other answerers have mentioned. [Answer] The chemicals that create bioluminescence in animals are often [highly toxic](https://phys.org/news/2012-08-bioluminescent-species.html). This could be a warning to predators, which is how it is often used in nature for terrestrial creatures, or a part of its hunting strategy. If the frill is spikey, like the quills of a porcupine, it could use them to poison and kill its prey. Obviously, the creature itself would be immune to this toxicity. This would have the added bonus of being a sort of area-of-attack weapon, which might be good for a blind creature. [Answer] Not all animals who live in the cave or who live nearby may not be completely blind like your creature. Maybe there are others who use very acute vision, who could see well with tiny amount of light. Or maybe they have their own sources of light, like the Angler fish which helps them see inside the dark caves. So while your creature is visually blind, it may still help it to have a intimidating frill to frighten off predators, and it can evolve while the creature itself is blind. [Answer] > > So why would it evolve something like that? > > > Because it evolved the frill before it became a completely subterranean species. Additional thoughts/uses: * The frill is an echolocation receiver (it helps capture the reflected sound waves). * It's a mating display, possibly with the bio-luminescent spots "looking" different to echolocation than the surrounding frill (the spots served as display while the species was sighted, and developed to remain a display while the creatures lost their sight) * Appearing larger than they are (anti-cannibalism: small creatures look larger from head-on, so larger members of the species don't try to eat them) ]
[Question] [ I have searched for a while now, but I cannot find a definite answer. A character I am writing has been captured by the antagonist, operated on and released, now completely mute. I've looked around for a bit to find a plausible way to explain him becoming completely mute, but cannot find one. Simply removing his vocal cords would still allow for some noises. Important: He has to look normal from the outside, so simply sewing his mouth shut or something similar is not an option. How can I justify this? [Answer] Your character has had a **laryngectomy**. <https://en.wikipedia.org/wiki/Laryngectomy> [![laryngectomy](https://i.stack.imgur.com/pQwrL.png)](https://i.stack.imgur.com/pQwrL.png) The removal of the larynx means that breathing happens through a hole in the throat (a stoma), and air no longer goes up to the nose and mouth. It is impossible for someone with a laryngectomy to choke on food. To make speech noises they need to learn esophageal speech, with gas routed up from the stomach (something like a controlled burp) or shape vibrations with the mouth using an artificial larynx. Laryngectomy is a big deal. It was a revolution when it was developed about a century ago. It is not a prank or punishment sort of thing that mean jailers would do to torture - it is done to cure cancer and it requires considerable skill to do correctly. Maybe your character suffered a cancer of the larynx some time prior and required this surgery? [Answer] If you wish to leave the victim otherwise intact, destroy the speech centers in the brain. If you damage the right areas, the victim will lose the very concept of words, so won't be able to comunicate through signs or text either. [Answer] Mutism is the inability to speak, not the inability to make any sounds with the mouth. Your character could become mute from a variety of causes. Willk suggests a laryngectomy, which would certainly work. With the right clothing, the person can look normal. Renan suggests causing aphasia with brain damage, which would also work, if done right (it could also cause damage that leads to changes that are noticeable). # Another possibility is a total glossectomy (removal of the tongue) While [some patients can speak afterwards](https://www.ucsfhealth.org/patients/brown_kate/), it's a long process that requires a lot of training and practice, and sometimes prosthetics. If your character's surgery was recent, speech wouldn't be there yet. While the woman in the article had a very invasive surgery, that was to get rid of cancer. A simple glossectomy would not be obvious from the outside, with his mouth shut. Another (very common) cause of mutism is physiological, called [selective mutism](https://en.wikipedia.org/wiki/Selective_mutism). It takes longer than an operation to invoke in people not predisposed to it. There's no real guarantee that's what you'll get, but it is a way to explain it, and there are no physical scars. (While most people with selective mutism can speak in some situations, some are completely silent 100% of the time for very long periods, even years. [Answer] dysphonia could also do this its basically your vocal cords don't work so great you have the inability or difficulty in getting air through your vocal folds one or both won't work. Just having one not working can cause slight to sever breathing issues so slight would be not really much but a sense the air isn't getting in no matter how much of it you breathe in. This can be due to stress. As someone who has that when its bad and not working I can be screaming and it comes across to someone else as a light barely there whisper. Other times I'm speaking and no one hears me at all I have to get right up to them and even then it can be impossible. I've had points where it didn't work at all and I was forced to just write. In moderate to loud places even just your home kitchen if its acting up you can't hear me over the noise. But anxiety can also remove the voice for while not forever anxiety has so many body pains and things it does to you lots of people don't know about effecting how your voice preforms is one of those. I'd imagine he'd have some serious stress after being operated on against his will. Having it apart of the strain of the forced surgery and the drugs used could work for a time. Inflamed ribs can do it too odd right? Well that works because the pain and inflammation of costochondritis also bleeds pain and tightness to the muscles, chest and neck area. Now make your character gain anxiety, costochondritis, and dysphonia all from severe stress and the surgery which costo can occur from due to the operation as well as for no reason at all given him a few days, months (or years) of bad pain from all of it and no voice he'll be writing on paper and feeling like shit and invisible in no time flat. I say this as someone who has the entire lot mentioned my costo was caused by mold in the work place. If you are going to make your character mute or nearly just know this is highly impactful to ones life no one can hear you if you can speak, the voice comes out as just air or not at all, it hurts to try to hold a conversation if you can have some speaking time at all. your entire way of communication is set to writing. Imagine being in the midst of pleasant and fun conversation you want to add a point by the time you've put pen to paper the topic is gone you have to learn to sit and just listen not respond in most instances. your friends try to include you but have to wait you boil an entire paragraph of words to two sentences to minimize the time the flow of the conversation is broken all because they have to wait on you. Convos involving you get shorter and shorter to make something short and legible you no longer have paragraphs and endless speech each word can take forever and musts be chosen deliberately on swiftest point and clarity rather then your normal speaking pace. Others wait with looks of impatience or annoyance and jokes may not be clear eventually you are just alienated from conversation all the time because its too much for them to wait upon and for you to highly filer what is inside your head bubbling to get out instead you must always choose speed and clarity to condense it all into just a few lines. This couples with depression and loss of control over your life in a lot of areas so maybe you want to show these things his recovery and coping to the new him would be difficult not to mention the violation of whatever that villain did to him on or off that table and the purpose behind it the what and whys would be long standing. ]
[Question] [ If you found out a way to produce a smooth icy surface on an ice moon like Ganymede, Enceladus, or Callisto, what kind of challenges would someone face if they tried to start ice skating? I figured you'd have problems with traction or staying glued on the surface in a low gravity world. Would this be possible? [Answer] First of all, the surfaces of these moons are *relatively* smooth; that is to say, given the resolution of our images of their surfaces, they look smooth from a distance but that isn't to say that the surface is ragged or textured in some way. If you look at pictures of the Earth from a distance for example, the oceans look smooth but they still have waves and in some cases quite choppy surfaces that just don't appear at that resolution. That said, assuming for the sake of argument you *could* find a pocket of the surface that is smooth enough, there are a number of other challenges that would make ice-skating difficult. The issue with weight in the lesser gravity is actually the easiest to fix, just like bouyancy in scuba diving, you simply wear weights. You could even use skates that are already weighed down so that traction is better. Of more concern is whether or not your skates could actually move on the surface. Enceladus for instance is supposed to have an ice coating of actual water, but it would be very cold on that surface. One of the reasons why skaters move so gracefully over smooth ice is that the friction of the blade actually melts the ice it travels over, and that ice either becomes slush on the surface or re-freezes, which is why ice skating rinks have to be regularly resurfaced. On Enceladus however, it is so cold that the ice would probably re-freeze (if the friction had any effect at all) so quickly that it could freeze your skate in place on the ice. Given that the temperatures on that moon are estimated to be around -201oC, it's even doubtful that there would be enough energy in the friction of the blade over the ice to heat it up to above 0oC, and therefore get it to melt. As such, your problem may not actually be too little traction, but too much. Finally, and perhaps most importantly, given that Endeladus has no atmosphere and is so cold, you'd have to be on the surface in a full space-suit. This is going to be bulky, heavy and may solve your weight problem in its own right, at least in part, but it's also not going to be super flexible and allow the movement that one needs to stay balanced on the ice. So assuming that the surface really is smooth enough (and it probably isn't), that the skate doesn't stick to the ice (and it probably will), you're still going to be in the exact opposite of a figure skating costume while on the ice, reducing your ability to skate normally (let alone do anything acrobatic or artistic) to almost zero. [Answer] **Let's take you at your word** We'll assume whatever technology is necessary to produce your skating rink has been provided. A nice dome, temperature control, a Zamboni, the works. What's left over is the gravitational difference between the moon and Earth. Would someone be able to ice skate? Yup, no problem. But there are some gotchas. An adult ice skating on a moon will weigh about the same as a child ice skating on Earth. So, from a very simplistic perspective, traction isn't the problem. The three primary problems are the adult's (a) mass, (b) height, and (c) strength. (You shouldn't be surprised that these three issues are tightly interrelated.) **Mass** The problem with mass is that it takes the same amount of force to move it around on a moon (or in space) as it does on Earth. All that's missing is the gravitational component that sometimes works in your favor and sometimes doesn't. Skating on a moon means the adult will experience the *weight* of a child. Since children can skate just dandy on Earth, the weight of a child (an adult) on the moon can skate, too. But the mass is another issue. If the skater gets moving too fast, they may not be able to stop because the mass is still there and requires the same stopping force as it would on Earth. But, with less *weight,* the edge of the skate may no longer hold the mass of the adult in place. **Height** Another problem is height, which in this case is a fancy word for "leverage." Remember all that mass we were just talking about? In an adult, a lot of that mass is a long way off the ground compared to a child. Attributed to Archimedes is the phrase, "Give me a place to stand and with a lever I will move the whole world." He wasn't kidding, leverage is a power multiplier, meaning a little force goes a long way. An adult's height could lead to the skater's feet stopping as expected, but their torso not stopping with them. The usual consequence is a sore bottom (but, with the lower weight, it won't hurt as much as your pride). **Strength** This is probably the greatest problem. An adult obviously has substantially more strength than a child (assuming equal weights, moon vs. Earth). That means an expected hop-and-spin might just land you in the bleachers. Or an expected turn might turn into an unexpected full stop. However, skaters would quickly learn how to "pull their punches" and exert less strength. The real problem is when they get back to Earth and all those atrophied muscles suddenly keep them from skating. *What this means is that an adult on a moon must skate like a child on Earth: slower, gentler, and with less self-consciousness.* [Answer] It would depend on the **temperature** and the **gravity**. Iceskating works (and ice is slippery) because of a [very thin layer of liquid water](https://www.youtube.com/watch?v=qd4CVvItJlo) on its surface. It's a combination of temperature differences at the interface and pressure applied on the ice's surface that make it possible to skate on ice. If the gravity is weak enough that a skater's weight doesn't produce enough pressure, and/or the temperature is low enough, it can become [physically impossible for ice to melt](http://www1.lsbu.ac.uk/water/water_phase_diagram.html) when the skates' blades come in contact with it. When that happens the ice stops being slippery and behaves like other types of rocks. You could probably imagine workarounds in some edge cases, for instance by heating the skates' blades to overcome too low a pressure applied on the ice or too low a temperature. ]
[Question] [ **Background** We know about the can-and-string telephone. [![enter image description here](https://i.stack.imgur.com/qJOmg.png)](https://i.stack.imgur.com/qJOmg.png) There are various claims about the maximum distance over which this is effective. Let's say 100 feet is possible without too much loss and distortion as hinted at here. <https://science.howstuffworks.com/question410.htm> A widespread and long-distance telephone network based on this technology clearly requires some way to extend this maximum distance. **Assumptions** The level of technology of this society comes before the invention of any electrical devices such as motors, lamps, heaters, batteries or anything else powered by or involving electricity. They have steam power and natural-gas lamps and other gas equipment. They can make machinery to good tolerances consistent with the above. We can assume if necessary that they employ brass or other corrosion-resistant wires under tension rather than string. These may be enclosed in pipes to avoid noise from the environment. The whole purpose is that people should be able to talk normally to each other so this is a telephone rather than a telegraph. **Question** Using only steam, gas and mechanical devices, how can they have repeaters in their system that both clean up the audio and amplify it for transmission to the next repeater? Maybe these amplifiers mean that much longer distances are possible between repeaters. [Answer] First, let me congratulate you for choosing a maximum 100' distance. While others argue about the longest that string can be, the reality is that every time you connect something to the string to hold it up you dampen the signal. so, ideally you want the pole holding the string up to actually be holding the repeater mechanism such that the string can hang free for highest quality transmission. **Cheap and it looks like it works: perfect government solution** My first solution is to use two funnel-shaped objects. The string is tied to the pointy ends and the whole contraption is mounted on a pole. One half (call it the incoming half) is acting like a megaphone to amplify the signal. The second half is acting as a compressor (think "stethoscope") to apply the signal to the next length of line. Because no active amplification is occurring, this would only benefit you for a couple of hops. It would need to be soundproofed to ensure the environment (dogs barking, rain falling) didn't drown out the signal. > > To amplify a voice effectively, a megaphone should be at least as long as the wavelength of the sound it's amplifying. Because human voices have wavelengths up to several feet long, the best megaphones (like the ones the cheerleaders use!) are usually manufactured as cones that are several feet long. ([Source](https://wonderopolis.org/wonder/how-does-a-megaphone-work)) > > > [![enter image description here](https://i.stack.imgur.com/LX5Wc.png)](https://i.stack.imgur.com/LX5Wc.png) Factually, this probably wouldn't work (or, its efficiency would be very low) because you have the same energy going out as you have going in. Megaphones aren't magic. They don't amplify anything. What they're doing is more efficiently transmitting sound waves (e.g., more of the sound you're naturally making is being directed toward where you want it to go). However, this works both ways and is therefore cool. This won't be the case with our next item. **But we want an actual amplifier, thanks!** Let's use water in the same way you use your car's brakes. the incoming sound is hitting a "master cylinder" full of water. The sound moves through the water to a secondary (and much, much smaller) cylinder. The output of that smaller cylinder will be amplified. [![enter image description here](https://i.stack.imgur.com/s8VXL.png)](https://i.stack.imgur.com/s8VXL.png) Note that we're not actually trying to move the sound "through" the water (in fact, moving the sound into a third medium simply reduces efficiency). What we're trying to do is move the water. Small movements in the master cylinder translate to large movements in the secondary cylinder. Factually, sound on a string probably wouldn't create enough audio-force against the surface of the water to get sound out the other end. Water might be too dense to do this with. However, it would make a cool experiment. The concept is sound, just the string might be a problem. The energy coming out the other end is very low. It might actually be easier (or beneficial) to use this other than a simple can to capture the original signal and boost it into the string. Also, this only works in one direction. You would need two strings, one to hear and a second to speak, for each user. **More complicated solutions** One ore complicated solution is the [compressed air gramophone](https://en.wikipedia.org/wiki/Compressed_air_gramophone) using a pneumatic amplifier. > > A pneumatic amplifier was realized by using a sensitive valve, which required little force to operate, to modulate the flow of a stream of compressed air. The basic principle of the valves used in these devices was to pass the stream of compressed air through two partially overlapping combs. The sound vibrations to be amplified were applied to one of the combs, causing it to move laterally in relation to the other comb, varying the degree of overlap and so altering the flow of compressed air in sympathy with the sound vibrations. > > > This would be the mechanically most complex and expensive solution (also requiring two-way communication), but it would allow you to transmit almost any distance. However, putting one of these every 100 feet would be... impractical. The cost of maintenance would infinitely exceed the value of the solution. [Answer] It seems that Sir Charles Parsons had partially solved the problem for you: Let me introduce the [**compressed air gramophone**](https://en.wikipedia.org/wiki/Compressed_air_gramophone): It was a gramophone (not interesting for you) coupled with a pneumatic amplifier that let the mechanical vibrations control a stream of high pressure air through a special valve. You can use this amplifier in your telephone system, but noise would probably overhelm signal after only a few retransmittings. It seems that [mechanical filters](https://en.wikipedia.org/wiki/Mechanical_filter) capable of acting as low and high pass filters were quite common, even to the point that they were included trough transducers into electrical circuitry, but obviously these can not remove all form of noise and correct more complex disortions. [Answer] Look up the [Pulsion Telephone](http://science.sciencemag.org/content/ns-14/360/434) - A mechanical telephone with a claimed range of 3 miles. This would let you greatly extend the distance you needed between repeaters. Another technology that may help create a solution is [Acoustic Mirrors](https://en.wikipedia.org/wiki/Acoustic_mirror) as passive amplifiers. And don't forget the power of human labor. A bank of "Telephone operators" hired to listen to the end of one wire and speak into the end of another solves the repeating and switching problems simultaneously. [Answer] There are several factors affecting the useful range of a string telephone, mostly concerning the transmission medium, i.e. the "string". 1. Modulus of Elasticity: Materials with a low modulus of elasticity do not require much force in order to deform them. In the case of a sound transmission medium, low modulus of elasticity means that the material will absorb more sound than a substance with a high modulus of elasticity, particularly in higher frequencies. 2. Density: Heavier materials require more force to move, so lighter materials will absorb less sound energy. 3. Friction: Friction between the moving string and the surrounding air will absorb energy from the string, so ideally the string would be suspended in a vacuum tube. So, given the steampunk setting, a reasonably available lower density material with a high modulus of elasticity might be a metal such as Beryllium. Osmium has a higher modulus of elasticity, but is much denser, and ceramics tend to have very high moduli of elasticity, but are brittle. An ideal substance would be carbon nanotubes, with low density and a very high modulus of elasticity, but this is not quite in keeping with the steampunk setting. As for amplification, a [fluidic amplifier](https://en.wikipedia.org/wiki/Fluidics#Amplifiers) has no moving parts other than moving streams of air or liquid, and hence is very robust and reliable. If miniaturized, they could have a frequency response sufficient to amplify the human voice. So, we can envision a system of beryllium or carbon nanotube wires running through vacuum tubes carrying sound, and fluidic amplifiers - and other fluidic logic components - in the place of an electronic or electromechanical telephone exchange. Given the propensity for the components involved to dampen high frequency sound, this system would sound much like a modern telephone system, since modern telephone systems also clip high frequency sound. However, the effective range of such a system may be somewhat less than an electronic or electromechanical telephone system, and it would have a higher infrastructure cost, especially if evacuated tubing was used to reduce friction losses. As any system with multiple booster amplifiers, eventually noise will be amplified to the point where the signal is lost in the amplified noise. [Answer] ## Use a spring and a pen So, the person sending the message will physically *tug* on a spring in a pattern matching the wave form of the message. On the other hand, the string is attached to a spring and a pen. The receiver moves a piece of paper at a constant rate while the string moves, drawing the waveform on the piece of paper. After the message is complete, the receiver can look at the waveform and infer what the message. ]
[Question] [ In my research on how I could get elves to live the time spans I wanted them to live, I came up with this solution: *Every elf generates while still developing inside the womb of the mother copies of his embryo which get stored somewhere in his body. Each time the elf reaches its equivalent of 60 years (human age) a hormone causes one of the embryos to share its DNA and within the next 3 to 4 years the elf gets his whole body replaced by the young body code the embryo has stored. during these 3 to 4 years the elf is very vulnerable and will sleep 90 to 95% of the day (the rest he will eat and drink)* *The Brain will be preserved by saving the connections the synapse had and connecting the new synapse in the same way. Let's say this works with 85% accuracy and always for the important part (close relatives, partner, values/character).* *This can be repeated to arrive in edge cases 1 out of 10 million at 6 000 years. Most elves only reach about 350 to 600 years. Oh and mutations of the embryos are kept in check by comparing the embryos. Let's say only 1 of 1 million mutations gets activated per embryo.* Now I wanted to know if this is feasible or not. [Answer] Completely replacing the body will be 1. Resource consuming and 2. Dangerous. **Resources** To entirely replace the body within three to four years, the metabolism would have to be in overdrive. Even in the best case scenario, real humans can't even beat 7 years in terms of body regeneration. Those are 7 years of natural sleep-wake cycles when said human can choose any of sixteen average waking hours to have food. Your elves, even at ninety percent of the day would only have two hours and twenty four minutes to eat. Their stress levels just to get a snack after waking up would rival those of the [antechinus in its mating rituals](https://www.cnet.com/news/meet-a-marsupial-species-that-has-14-hour-suicidal-sex-marathons/)- and it dies at the end. Plus, the amount of water they would need to sustain this would be gargantuan. Even when those requirements are met, what about when the GI tract is regenerating from that of an embryo? **Danger** Cancer. They are regenerating their bodies very quickly and in large chunks. Looking at cells in our bodies that generate very quickly, we find high cancer rates. Cancers in the GI tract and skin are some of the [most common](https://www.cancer.gov/types/common-cancers) in part because the cells there generate very fast. Cancer is the most dangerous risk, but there are others as well. If your elves are around lead (or any other developmentally harmful chemical), they could end up with a messed up body for the next 60 elf years. **But there is still hope for great longevity** Maybe the elves don't need something as complicated as generating whole bodies. A few alternatives to longevity: * [Telomerase](https://en.wikipedia.org/wiki/Telomerase) to prevent aging of the DNA * Many copies of [p53](https://en.wikipedia.org/wiki/P53) to help fight cancer. [Just look at elephants](https://www.nature.com/news/how-elephants-avoid-cancer-1.18534). * A slower metabolism is optional. This works for many animals, mostly fish and reptiles. [Answer] I think you aren't talking about embryo's, but stemcells. The embryo starts with splitting itself into stemcells that can specialize into anything, and some of these stemcells are still present in adult humans right now and science is using them to learn and create new organs, they can already create individual cells. Renewing parts of the body with stemcells could be possible, but it would be immensely complex. You need to migrate the stemcell through the body to the right spot, ehich is possible but not exactly accurate. Then you have the cell replicate to the right celltypes and need a complicated set of checks and balances to make sure old cells die and are replaced without interfering with the body's normal functioning. Then theres the nervous system with the brain and spine as its centerpiece. The brain is a tricky thing and I got taught that the brain is both extremely set in its ways with nerves that carry specific tastes and things and on the other hand extremely malleable allowing parts of the brain to take up more space or even managing to lose half of the brain and have lots of those functions be managed by the remaining half. So potentially you would be able to have a piece of brain specifically for storing information of a brain area that is being rejuvinated, upon copying the old area gets shut down (to prevent interference) and a few bypasses to that brain area are made. Expect sometimes a slower response for brain area's that are stored on the temp storage brain. Still, you are looking at accuracy of the migrating stemcells and an even more complex system for replacing. With skin or bone its not a problem if it accidentally replaces a bit too much, with brain or nervous systems it could erase an important reflex, memory, muscle action or even cut the connection between parts of the body. [Answer] What you're describing is in effect an internal, biological form of [gene therapy](https://ghr.nlm.nih.gov/primer/therapy/genetherapy), an experimental medical treatment that seeks to treat or cure disease by altering the genes slightly to make the person being treated more resistant to the disease in question. The problem is that we don't really understand what causes aging just yet, but one theory relates to a component of DNA called [Telomeres](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2995895/), which appear to shorten with each replication of that DNA, ultimately putting a limit on the number of replications that can occur within an organism. The link also gives a wide range of different aging theories, all of which may assist you with forming your own conclusions regarding your answer. To me though, the single biggest issue here would be longevity of the 'embryos' within your elf. It is generally believed in scientific circles that women are born with all their possible eggs within them, although there's been some recent debate about this given the discovery of stem cells within the ovaries, but in any event, women are born with a LOT of eggs inside them. The problem is, they start to die off immediately and continue doing so. By the time a woman reaches menopause, the few eggs remaining to her are more or less unviable. IVF has cheated this and allowed older women to have children by re-implanting eggs that have been harvested previously and fertilised, but generally speaking, a woman's eggs are not going to last 100 years, let alone 600, and your elf will suffer the same problem. At the end of the day, especially in a warm blooded species, all parts of the body are going to be subject to entropy to a greater or lesser degree and given the sophistication and delicacy of DNA, the odds of keeping renewal gene pods inside a warm body for centuries, not subject to the normal renewal processes of the body and not subject to normal biological breakdown are remote. In addition to this, there are two other factors that you really need to consider. Current natural DNA replication methods have many checks and balances built in already to stop errors (read as mutations) being introduced. These are not perfect, but given the amount of work they do over the course of a human lifetime, they're VERY reliable. Your design effectively hacks that process once every 60 years or so and feeds it a new template, which introduces all sorts of risk vectors. For one thing, diseases now have a new mechanism that they can exploit to get DNA to replicate of a different template completely, potentially introducing a runaway cancer scenario that effectively uses the body of the elf as raw material for the production of cancer cells on a massive scale. Additionally, memories are even trickier. The problem is that we really don't know how they're laid down or stored in the brain, despite a lot of research in this area. It's possible that memories are just encoded electrical circuits in the brain, in which case you really don't want 'renewal' in that part of your body as it could potentially cause massive disruption. If memories are somehow encoded into the cells or into the pattern of connection between brain cells, renewal could be even more disruptive to memory, personality, etc. In short, you're trying to bypass the natural aging process by internally storing cells that somehow bypass the aging process. Is it *possible*? Yes. But, it's highly unlikely and would involve organic 'storage' mechanisms that have yet to evolve despite them having a material benefit to procreation before longevity. ]
[Question] [ An island nation has a lot of coastal territory and has become gravely concerned about the threat of global warming. They've decided to fix this by launching reflective satellites into orbit -- similar to [China's man-made moon](https://www.esquire.com/lifestyle/a23937900/china-man-made-moon-launching-2020/) plan, but instead of reflecting sunlight to Earth at night, they're reflecting sunlight away from Earth during the day. Is this viable? I assume it's not actually viable since real-life geoengineering efforts seem to be mostly interested in adding reflective material to the atmosphere. But what's the problem? Does it take an unreasonable number of satellites? Are the satellites too expensive even when bulk-manufactured? Are the satellites too expensive to launch into orbit? Do the satellites get damaged too quickly by orbital debris? Is there some sort of weird thing where the satellites act as solar sails and the pressure pushes them out of orbit? Or is it just that the satellites fly over countries that would prefer not to suffer eclipse conditions most of the time? [Answer] # Could we do this? Yes, we could. [It's been proposed before](https://www.forbes.com/sites/startswithabang/2018/05/26/ask-ethan-can-we-build-a-sun-screen-to-combat-global-climate-change/#18e6aa8d1f00) in a number of forms. Most calculations agree that [this sunshade](https://en.wikipedia.org/wiki/Space_sunshade) would need to reduce solar insolation by anywhere from 2-10%. If we take an optimistic figure - the lower bound of 2% - then we could achieve this by putting a shade 4.5 million square kilometers in area at the Sun-Earth Lagrange point, $L\_1$. Alternatively, we could send [16 trillion tiny satellites](https://www.eurekalert.org/pub_releases/2006-11/uoa-ssm110306.php) there, or put a [1 million square kilometer lens](http://adsabs.harvard.edu/abs/1989JBIS...42..567E) at $L\_1$. # What are the problems? This *might* be technically feasible. However, there are some barriers to it. * Given current launch costs, these plans would require perhaps hundreds of billions of dollars. * $L\_1$ isn't stable; we'd need to continuously adjust the orbit of every object we place there. This costs money, too. * You'd probably have to get the agreement of most countries before undertaking a project that would affect literally the entire planet. Physics says that yes, this can work. But it would require orbital readjustment, a large amount of money, and international agreements. # Other notes As jamesqf noted, this plan would *not* reverse effects of global warming like ocean acidification. These are directly related to the concentration of greenhouse gases such as carbon dioxide and methane, and we would need to reduce levels of those if we wanted to avoid certain catastrophic effects. Additionally, it wouldn't be great to put the satellite(s) in orbit; they have to go to $L\_1$. Why? Satellites spend half of their time on the daytime side of Earth and half of their time on the nighttime side of Earth. This means they would only be blocking sunlight for half of their orbits. Putting them at $L\_1$ is much more effective. As a final thing to keep in mind: Placing these objects at $L\_1$ won't cause an eclipse or any similar effect. The umbra will not reach Earth. Instead, the satellites will simply decrease the overall amount of sunlight we get, rather than completely blocking any particular area. [Answer] Just to throw some numbers out, the space shuttle could deliver a 65,000 pound payload into space. To do this, it used 2.8 million pounds of fuel. Sources: * [NASA Space Shuttle FAQ](https://www.nasa.gov/centers/kennedy/about/information/shuttle_faq.html): 1,607,185 pounds of fuel in the External Tank and internal. * [Cool Cosmos](http://coolcosmos.ipac.caltech.edu/ask/268-How-much-did-the-Space-Shuttle-weigh-): 1.1 million pounds in each rocket booster (two); 65,000 pound payload. Space X's [Falcon 9](https://en.wikipedia.org/wiki/Falcon_9_v1.1) produces an estimated [250 thousand kilograms of carbon dioxide](https://www.quora.com/When-Elon-Musk-launches-a-rocket-into-space-is-he-releasing-more-carbon-which-is-what-he-is-trying-to-reduce-through-electric-cars) per launch and has a payload of 13,000 kg. Using the [energy content](https://www.engineeringtoolbox.com/energy-content-d_868.html) of kerosene, that's about four billion BTUs per launch. So 13 Mg of reflectives would have to more than counteract four billion BTUs plus the greenhouse effects of 250 Mg of carbon dioxide. Plus of course the amortized carbon cost from building and operating the Falcon 9 (e.g. moving it from its landing area to its launch pad). [One proposal](http://www.bbc.com/future/story/20160425-how-a-giant-space-umbrella-could-stop-global-warming) would use 16 Tg of reflectives. That's more than a million Falcon 9 launches. This would be much more feasible if the reflectives were built in space and moved into position by solar sail. Some will point out that we could instead burn hydrogen. Of course, that produces water vapor, another [greenhouse gas](https://www.ncdc.noaa.gov/monitoring-references/faq/greenhouse-gases.php?section=watervapor). It's less of a greenhouse gas than carbon dioxide, but hydrogen is also less energy dense than kerosene. [Answer] Just use glitter!! There are some real world proposals to use a cloud of glitter as a mirror <https://www.jpl.nasa.gov/news/news.php?feature=4553> > > In the proposed Orbiting Rainbows system, the small cloud of glitter-like grains would be trapped and manipulated with multiple laser beams. The trapping happens because of pressure from the laser light -- specifically, the momentum of photons translates into two forces: one that pushes particles away, and another that pushes the particles toward the axis of the light beam. The pressure of the laser light coming from different directions shapes the cloud and pushes the small grains to align in the same direction. In a space telescope, the tenuous cloud would be formed by millions of grains, each possibly as small as fractions of a millimeter in diameter > > > It only stands to reason if you can use it to capture images, you can also use it to reflect unwanted sunlight. Then it's just a matter of scale. Another big advantage is, think if it gets hit with orbital debris or meteorites. So what it punches a hole in a cloud of glitter. Adjust the lasers a bit, no hole. **A Bonus Idea** As a bonus idea, it would be worth while to convert the sunlight into electricity. In this example it would take more advanced "glitter" but the biggest stumbling block would be transmitting the power, not actually generating it. But this way, not only are you "shading" the planet and reducing the temperature, your also supplying a large amount of (essentially free) solar electricity. Which would also be beneficial to any climate change scenario as it would cut down on the use of power generation on the planet (fossil fuels, nuclear waste etc..) Cheers! [Answer] As others have pointed out, it's theoretically, if not technically possible or feasible to shade the earth, but we are faced with the fact that most of our tech and accessible resources are inside of a large enough gravity well, that will likely continue to pull-in more material (~40Kt) per year than we will ever be able to launch, with current launch systems. But we can bootstrap the process: You would only have to launch automated mining and manufacturing equipment to begin the process of building a self sustaining space economy that lives off of the material available in tiny gravity wells (asteroids/comets/Moon), and uses abundant solar energy to power it all. And most of what does get launched from earth, would have to be inserted into LEO by electromagnetic means (rail/coil guns. Elevators are presently off the menu). We could probably build practical guns with current tech, that could place bulk materials into orbit, but they would subject their payloads to such extreme accelerations, that most assembled equipment and no human could survive. The bulk of the parts and raw materials could be launched that way, for assembly in orbit. But, since nothing below escape velocity can avoid falling back to earth, you'd have to have some space tugs out there, to intercept the payloads and move them into stable orbits. The first hurdle would be to construct the guns, which would be nearly vertical structures built at high altitudes, and rising 20km or more. The longer the gun, the lower the mass of atmosphere, that the projectile must decelerate through, to be reachable by the tugs. Such a structure would have to be flexible and dynamically stabilized by a variety of means, including thrusters, which would also be needed for aiming. While that's happening you need to get out to some carbon and ice bodies where you can make fuel. We can launch the first tugs and some fuel into orbit using rockets, but acquiring fuel off-world, would be the highest initial priority, to keep the tugs running. The tugs wont be able to use solar power for propulsion, because they will be entering the upper layers of the atmosphere, where solar panels would produce too much drag, and they are going to need a lot of thrust, so that means chemical propulsion. It's possible that a hydrocarbon based fuel could be a good choice, at least initially, as it might produce enough smog to temporarily cool the planet (TBD), but there's plenty of hydrogen and oxygen out there that can be produced using solar power, and those two elements would likely be the least environmentally damaging in the long run. Next you launch a minimal number of assembly stations via rockets. These will be used to build more robotic stations as supplies arrive from the guns. They can use solar power and ion thrusters for maneuvering and stabilization. When you get your orbital production levels high enough, you can start using some of it to build miners and transports. With those, you can get out to the metallic and rocky bodies to start mining the rest of what you need. At some point you will rely entirely on off-world resources and disassemble or mothball most of the earth-bound launch systems. ===== An alternative would be to use rockets to provision the surface of the moon with robotic miners and assembly systems. If you can produce Teflon and/or carbon fiber on the moon, then you can build space elevators there, greatly reducing the need for rocket fuel. Guns also work there, for launching large masses into space. Lacking an atmosphere, and having far less gravity, you can use guns to safely launch humans into space from the surface of the moon. The moon is ideal, but to get there with enough equipment to bootstrap the process at a high enough rate to build your shield in time to prevent total collapse of the earth ecosystems, you'd still need to build some guns on earth, to deliver the initial equipment. ===== The current limit of human built vertical structures, is <1Km. The tallest buildings, use dynamic stabilization for human comfort and to prevent destructive oscillations, driven by the winds. The structures needed for rail or coil guns, would not in any way be built for human comfort, so their total mass/km would be a great deal lower than our current tallest buildings. I don't think it would be too much of a stretch to push the limit to ~2Km with current construction technologies. That's an order of magnitude lower than you'd need for a practical system, so we'd have to invest more in materials research and divert a larger fraction of our hydrocarbon production into making Teflon, graphene's, carbon fibers and other advanced materials. It is likely that in the short run, you'd have to deploy some vertical thrust to keep the gun from collapsing. This could be provided by electrically driven fans. Rather than model the gun as a vertical spike, it would be more like a stiff rope or conduit, that could possible be leaned over/curved to some extreme angles (10 degrees maybe?) for aiming purposes. Some modeling of the atmospheric effects of operating such a structure for up to several decades, would be very important. Such a system would have it's own, local, small redundant nuclear power plants, in addition to being connected to the power grid, to ensure the structure doesn't collapse unintentionally. ===== The key economic benefit of using guns, even when they must be permanently supported by some thrusters, is in the avoidance of the rocket equation. You don't have to lift any fuel, to provide lift a second later. And electrically driven propulsion all around, is more environmentally safe. They are the only way we can bootstrap any kind of major push beyond our gravity well, without destroying the ozone. ===== Elevators to earth orbit, currently require the use of unobtanium. Graphene and carbon nanotubes have been ruled out, because they don't have the required tensile strength and those were the previous front runners. [Answer] \*\*Satellite Design \*\* If you wanted to use satellites to decrease climate change, then you would either need lots of very large, reflective, and heat absorbent satellites. Another way that you could use satellites is by having them use some kind of filter or collection device within the atmosphere that would gather up pollutants like carbon dioxide for the satellite to then retrieve and find some way to dispose of. ]
[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 5 years ago. [Improve this question](/posts/128160/edit) If you search "medieval crate" on google you get 2 things: 3D crates that look suspiciously modern or you get real, chest-like boxes. I'm wondering if the latter is the norm for the time period? [Answer] **No Standard** As Jamesqf suggests in the comments that while there was no standards for shipping. so each and every company had different sized contains depending on what they were making. and i mean making, in all likelihood it was the goods manufacturer that dictated the container not the shipping company. **What has survived** There have been many wrecks that have been investigated over the last century and these range drastically in their size and range as well as their period and country of origin. Clay jars, or Amphorae have been found throughout the ancient times, but this was mostly for storing small loose matter such as grains and liquids. in the medieval times Barrel making had advanced past the use of clay pots for this purpose so its likely that this was indeed the equivalent of a standard for the time as it was reasonably cheap for how long their lasted, and weren't fragile compared to amphorae. **What hasn't survived** The most likely method of transporting non fragile goods would have been in sacks or woven baskets. these wouldn't survive the test of sea water and time, but allowed for large amounts of goods to be stored in a small amount of space, which meant people and shipping companies could carry more and therefore make more money. Anything really fragile would probably have been placed in some form of handmade wooden create if absolutely necessary, perhaps lined with some form of protective cloth based or wood chipping material to act as packing. **TLDR:** Handmade wooden crates very rarely, more often Baskets, Sacks and Barrels are the most likely storage vessels in medieval shipping. [Answer] Depends on the goods you wished to transport. I've generalized here, a very dangerous thing to do for an era that spanned from the 5th Century to the 14th or 15th, with massive variation from country to country. So, I've given an overview, but use that as a jumping off point to get specific. Pick a country and a century and go from there. * Barrels. Pretty much came into vogue in the Medieval period in a BIG way. Used for all kinds of things, not always liquid goods like alcohol. Fish were sometimes stored this way, and sometimes even kept alive with water in. Herring were always packed, pickled and salted in barrels. Barrel hoops were mostly made of wood, flexible willow, ash, hazel, and chestnut. Though metal hoops were used, they weren't very common for most of the medieval era. (If they were metal, it was a high quality barrel, mostly in use for alcohol, starting in the high Middle ages after about 1000). But the barrels themselves could be anything--pine, oak, whatever it might be. Later barrels for alcohol got to be exclusively oak. Metal hoops weren't used commonly until well after the Medieval period. If it was a wet good, it would be made waterproof, but for dry goods, like nails, fruit, gunpowder, sugar, flour salted meats and so forth, it was not. Take a look at the wiki for [coopers](https://en.wikipedia.org/wiki/Cooper_(profession)) who made the barrels and there was a seperate one I believe for hoopers, who made the hoops to go round the barrels. Barrel sizes were NOT uniform, so whatever picture you have in your mind as far as how big they would be on average, dismiss that right now. During this time they were often longer (or taller) and thinner than a modern barrel. There were tiny casks, and giant ones and everything in between, with no standard. (Except within industries in certain countries--some places would get serious about some food good like herring or wine and establish a standard--but JUST for that particular good in that country). * Sacks. Barrels were more secure and there was less chance of rats getting to the goods, so not as common in long-term shipping. * Woven baskets. Stackable and made with handy handles. * Chests. Used for moving mainly and doubled as furniture. You already know about these. * Rope handle chests. Here's a picture: [![enter image description here](https://i.stack.imgur.com/qHcaf.jpg)](https://i.stack.imgur.com/qHcaf.jpg) Yes, it's a modern construction, but it's not that hard to build. Not nearly so common as barrels. On a long-term voyage this could keep rats out. For short term trips, sacks and woven baskets would be more common. Ease of carrying is a big factor. Although they did have windlasses and pulleys, those were likely not guaranteed at every port. These smaller boxes with built in handles meant that boxes could be loaded on and off with a minimum of fuss. * The standard nailed crate. This is a modern image taken from a game but, it's accurate as far as what they could build and what was used for a long time. Though these could be built, again, not as common as barrels because you could not roll these like you could barrels. But they were used. Came into use more in the late Medieval, but you could find these anytime during the period. [![enter image description here](https://i.stack.imgur.com/wlvlT.png)](https://i.stack.imgur.com/wlvlT.png) * Cages. For live goods such as chickens. Made of wood. * Gourds or Ceramics. You might not realize how advanced woodworking was. Making nice, uniform planks was something that they had to do for shipbuilding and they had LOTS of practice. All my images are modern, but that's because preserving these was not considered important. It's like the equivalent of saving cardboard Amazon shipping boxes. Many were stamped with what goods they were, sometimes for tax purposes. What was used most often were barrels. Yes, you had the other containers, but barrels were easier to roll to their destination. Everything else was less in use. Basically, if you COULD put it in a barrel, they did. This includes fabric. I know, insane. They would put them in rolls and into a barrel they could go. Fabric was also just stored in boxes, or as loose bolts. I'd say, that your best bet to start is just to become a barrel expert. Here's a start with [this link!](https://stravaganzastravaganza.blogspot.com/2014/12/history-of-barrels-in-middle-ages-surge.html) That will tell you a lot about the standard sizings for shipping specific goods (mostly alcohol). **Medieval times were the AGE OF the Barrel! Cause you could roll 'em.** ]
[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/125834/edit). Closed 5 years ago. [Improve this question](/posts/125834/edit) For the sake of making things much, much simpler, most worlds I'm familiar with have a defining feature of language: there is a common language. This allows for universal communication and overcomes what would otherwise be time-limiting obstacles for one species (or race) to communicate with another. However - my question here revolves around the fact that we can't always be so lucky. What if there was no universal language? What if the biology of the two species was different enough that they had defining phonetic differences (which, I think, should be the more likely scenario whenever there are two intelligent species coming into contact with one another). Imagine if you were to introduce to a human species an intelligent species with all the defining characteristics of the human phonetic biology (esophagus of relative length, vocal chords, lips, teeth, shape of mouth) but they were missing a tongue. The time to develop a universal language would take time - and that's given that humans *with* tongues can talk like humans *without* tongues. I'm looking for the best example of how this might have occurred historically (among new civilizations meeting and who had no idea how to translate each other's language) or fantasy-historically (a permanent language-replacement which shows the best example of massively reducing the time taken for written translations). I am not looking for any example of a "Universal Translator" type answers, as that answer is the equivalent of everyone being able to inherently speak the same language, unless it's a well established methodology which has been taken into serious consideration. [Answer] The most common solution the real world is the development of a trade language or lingua franca. Remember, language doesn't need to be verbal, especially if there are key anatomical differences. It could be a sign language or written one or if the technology exists, a translator. [Answer] If I remember correctly, humans and aliens in the movie **District 9** express themselves in their respective languages—they have learnt the other species's language without being able to vocalize it themselves. Douglas Adam's **The Hitchhiker's Guide to the Galaxy** has the babel fish. **Farscape** has translator microbes. [Answer] The problem is a lot broader than you may suspect. Different biology for vocalisations is one thing, but what about species that communicate by pheromone? Lighting up thinly covered bone plate in different sequences by flushing blood into their membrane coverings? These are just some of the possibilites; communicating with each other is hard enough when we belong to the same species. With aliens we haven't even begun to scratch the surface. So how *would* we learn to communicate? Here are just 2 possible options; **1) Science & Math** The periodic table of the elements should be the same for all of us, no matter species of origin. This is a good representational place to start. We can then also teach math - hydrogen has 1 proton, helium 2, etc. Then we can teach true / false or yes / no concepts with 1+1=2 is true, 1+1=3 is false, etc. There are going to be some massive differences in psychology to conquer and other misunderstandings based on how we all represent our science, but it's generally thought that math and science make useful 'rosetta stones' for other potential species out there. **2) Measure of Actions** In the first instance, we have to make an assumption that aliens will want to talk about the things that they care about. This may very well not be the case, but if we at least assume that they *want* to communicate with us, they'll try to make it easy for us just as we'll try to make it easy for them. Pointing to chairs and saying their equivalent of 'chair' for instance. Aggressive stances against us may well represent offence or anger, whereas less dominant posturing may indicate agreement. This approach is less scientific and relies on many assumptions about their intent and psychology that will ultimately prove wrong many times, but if it is two 'enlightened' species trying to communicate with mutual intent, all you really need is patience. In the end, it may all come down to writing, though. We have to assume that a developed species is in essence a species of tool builders, meaning that they probably have some form of representational alphabet or written language which we can work with. It also has the benefit of being still around after they've lost patience. There are good reasons to write down knowledge, regardless of species. It affords a cheap and effective means of passing information around your community, thus improving it at a far greater rate than having to learn everything from another in verbal repetition. So, for mine, the written language will be (once we've figured out *how* their language works) the principal method by which we would communicate with alien lifeforms. [Answer] Writing like hieroglyphs or Chinese seems the obvious choice. Lots of ethnic Chinese languages are not mutually comprehensible but use the same symbols. Linguists can understand some ancient languages via their writing when they don't even really know what they sounded like. Hearing impaired people can communicate via sign language. So basically if it's impossible to articulate the correct sound or decipher them hearing them, then swap audio for visual language. [Answer] I don't see the problem with a Universal Translator. Of course its a go to solution but its one that works. The universal translator converts everything you hear into English with perfect accuracy. Every space faring civilization eventually develops their own one, so as a Human I don't need to speak in bubbles or clicks, the Aliens universal translator converts my language into theirs. You could do it both ways, however that complicates it because you have an echo when talking and that is often undesirable in conversations, games and movies where this is often applied (Like listening to a DUB while the original voice is going and with a few seconds of delay). The issue is that something simply can't be pronounced due to physical differences and methods of communication. Lets say that dogs developed a language using barks and high pitched whines. But we as humans can't hear the upper range of the whine much less produce it so that entire part of the language is unpronounceable and unhearable to us. We have to rely on some form of technology to translate it, and a universal translator software is simply the easiest choice. Every time you meet a new species, a bunch of linguists sit down, get some objects, show it to each other and say the words until you have developed a common framework between the two languages. You work together as 2 species to unite your languages and all the intricate features like idioms, similes etc etc and then push the new language update onto all the devices and now 2 entirely separated species can talk to each other. Now if you want to go into the specifics of a universal translator and making it as realistic as possible, that is a completely different scenario. But if a human can learn to speak more than one language fluently, there is no reason we couldn't teach a computer the same thing. [Answer] Universal translators are not going to happen. Things are always getting lost in translation. So, xenos visiting Earth will have to learn the local language, Chinese. If *I* were to learn Chinese I would have an accent. Probably a really bad one. But with a bit of patience and a well-meaning Chinese native, we could communicate. If *a xeno* were to learn Chinese, their accent would be horrible beyond comprehension. Also, their hearing would probably not be tuned to the differences needed to tell Chinese phonemes apart. What is needed is an **automatic accent corrector**. Whenever a Chinese would say (Chinese r) the aliens would say (Xeno phoneme 1), and so on for every phoneme needed. If the xenos has at least the same number of phonemes available, we are done. If not, we need to use combinations of xeno phonemes to represent Chinese ones. I think we are at the point now where a computer can be programmed to automate this process. So, a Chinese says something. This is "transphonmed" into something the xeno can hear and recognize. The Xeno answers in their horrible accent. The computer "transphonmes" it into correct Chinese. Of course, alternatively they could just communicate in writing. ]
[Question] [ I am writing a short story in which a character is ejected out of an air lock in a space ship. He quickly re-enters (disregard how he does this) and the chamber re-pressurizes, but he is exposed to space for about nine seconds, and without oxygen for about 12 seconds. Given that the plot then has him engaging in a fire fight essentially right away, I was wondering how realistic such a scenario was. Based on [an article I've found](https://science.howstuffworks.com/question540.htm), the character (who we'll call Dave), would lose consciousness in ~15 seconds from lack of oxygen. His blood would begin to boil and tissues expand. He could be exposed to extreme temperatures, irradiated by the sun, and even riddled by dust or debris. **Question:** Assuming Dave escapes anything lethal (by some miracle of plot armor, no doubt), what are the best and worst case scenarios for his immediate physical condition once the chamber re-pressurizes? I'm basically looking for a range which I can work in. ie: In the department of space dust/rock, the best case scenario is that he escapes injury entirely. The worst case scenario, short of lethal damage, is that his spinal cord has been punctured in several places, leaving him unable to move. I'm looking for something along those lines, though obviously with a bit more explanation/evidence to back it up. [Answer] The [wikipedia article](https://en.wikipedia.org/wiki/Space_exposure) has an acceptable summary of existing research and incidents (but make sure to read the articles in references, they are more informative). In short: * loss of consciousness in about 15 sesonds * fatal if not repressurized in 90 seconds or so * lungs might burst if the person is trying to hold breath If you worry about being riddled to dust by debris (in those 90 seconds), you have much bigger problems - like your space station being riddled to dust as well. Temperature changes, irradiation etc. are relatively unimportant, unless your station is orbiting Mercury. The character would not have time to freeze to death - vacuum is a very good insulator, and what cooling is there by evaporation won't be so quick. [Answer] Perhaps the best science-based answer can be found here [Survival in Space Unprotected Is Possible--Briefly](https://www.scientificamerican.com/article/survival-in-space-unprotected-possible/) All quotes are from this article. > > In reality, however, animal experiments and human accidents have shown > that people can likely survive exposure to vacuum conditions for at > least a couple of minutes. Not that you would remain conscious long > enough to rescue yourself, but if your predicament was accidental, > there could be time for fellow crew members to rescue and repressurize > you with few ill effects. > > > and > > But death is not instantaneous. For example, one 1965 study by > researchers at the Brooks Air Force Base in Texas showed that dogs > exposed to near vacuum—one three-hundred-eightieth of atmospheric > pressure at sea level—for up to 90 seconds always survived. > ... But after slight repressurization the dogs shrank back down, began > to breathe, and after 10 to 15 minutes at sea level pressure, they > managed to walk, though it took a few more minutes for their apparent > blindness to wear off. > > > With the caveat > > Water and dissolved gas in the blood forms bubbles in the major veins, > which travel throughout the circulatory system and block blood flow. > After about one minute circulation effectively stops. The lack of > oxygen to the brain renders you unconscious in less than 15 seconds, > eventually killing you. "When the pressure gets very low there is just > not enough oxygen. That is really the first and most important > concern," Buckey says. > > > It's not how much oxygen is in the body (thus holding your breath is irrelevant but dangerous) but how it is ported to the brain. > > Chimpanzees can withstand even longer exposures. In a pair of papers > from NASA in 1965 and 1967, researchers found that chimpanzees could > survive up to 3.5 minutes in near-vacuum conditions with no apparent > cognitive defects, as measured by complex tasks months later. > > > and > > For example, in 1965 a technician inside a vacuum chamber at Johnson > Space Center in Houston accidentally depressurized his space suit by > disrupting a hose. After 12 to 15 seconds he lost consciousness. He > regained it at 27 seconds, after his suit was repressurized to about > half that of sea level. The man reported that his last memory before > blacking out was of the moisture on his tongue beginning to boil as > well as a loss of taste sensation that lingered for four days > following the accident, but he was otherwise unharmed. > > > So, extrapolated, it is reasonable to assume that perhaps ten seconds of exposure, and twenty seconds of recovery could give the results you are after. ]
[Question] [ Would it be possible for a race of [crustacean](https://en.wikipedia.org/wiki/Crustacean) humanoids to live as nomads in a desert environment? I want them to have crab-like faces and crab-like skin with humanoid bodies. Would they survive in that environment? What would they need to survive both biologically/anatomically and clothing/equipment wise. [Answer] True crustaceans would have a hard time living in a desert environment since they have gills that need to stay moist at all times. For example look at the distribution of [woodlice,](https://en.wikipedia.org/wiki/Woodlouse) which are our own version of terrestrial crustaceans. They live mainly in damp environments like under logs although there is apparently [a desert species.](https://en.wikipedia.org/wiki/Hemilepistus_reaumuri) But you could handwave this without that much issue. Your nomads would need to trek at night and from burrow to burrow, foraging along the way or finding food underground. You'd need quite a lot of fossil water to keep the burrows or caves damp, maybe a [Karst-like](https://en.wikipedia.org/wiki/Karst) landscape. As for equipment, something like a damp towel wrapped around the air-vents could give the nomads some more capacity to deal with heat and drought, I'd imagine them being in use by the hunting class or during emergencies, something high-status maybe. It sounds like a unique and challenging environment, good luck! [Answer] If you mean a hot desert, a crustacean as large as a human would cook during the day as it would have no way of regulating its body temperature being cold blooded made worse by being encased in a giant exoskeleton. In order to survive it would need water perhaps a large oasis which it could climb into to avoid the temperature excesses. It would be able to emerge from the water a few hours before and after dawn and dusk and perhaps at other times for a few minutes. Movement at night would also be problematic due to the low temperature, but slow movement might still be possible. In order to survive on the land during the heat of the day the creature would need cooling, perhaps by painting its shell white and perhaps also in the form of a large sunshade. Large volumes of water would also be beneficial which it could spray on itself to provide evaporative cooling. [Answer] If you are willing to walk a bit up the family tree from crustaceans to their phylum arthropods you can find a number of insect and arachnid cousins who have adapted to live in desert environments. I'm thinking scorpions specifically. But... The biggest problem you will face is likely based on size rather than specific environments. Exoskeletal creatures are limited in how big they can be due to a number of reasons such as; limited oxygen absorption without lungs, underdeveloped circulatory systems, structural support for large creatures without bones, etc. The largest arthropod (exoskeletal) creature currently is the coconut crab which can get to a respectable 1 meter across, but only weigh about 4 kilos. You would have to overcome these structural problems first for your large humanoid crustaceans to exist at all let alone adapted to a desert environment. [Answer] As the others have said, the biggest problem about crustaceans in hot and arid environments is that their shells do not allow them to release heat. On the other hand their shell could also stop most of the heat from going in. It is hard to say, since we do not have many dryland crustaceans and even other life forms still try to stay inactive during the day. But I think that a less heavily armored body could be plausible, if we take a scorpion as an example(it's an arachnid, but it is probably the closest thing to a crustacean that lives in deserts). A scorpion is able to deal with heat, but it is still armored. So reducing the thickness of the plates and giving them a bright colour and adding some cooling parts should do the work. [Answer] Here is what I envision: a round, nearly spherical body. This would minimize surface area to volume and so be the slowest shape to heat up. The same high volume to surface area will minimize water loss. Appendages will be very long and minimally perfused - that gives you the height and size you want without increasing volume much. Basically it will be a head with long spindly legs and arms. This converges on the body plan of the harvestmen or [opiliones](https://en.wikipedia.org/wiki/Opiliones), a distant cousin of your crustaceans but with a pretty crustaceanish face. <http://infinitespider.com/wp-content/uploads/2015/08/Robswatski-flicker.jpg> [![daddy longlegs](https://i.stack.imgur.com/VjAEH.jpg)](https://i.stack.imgur.com/VjAEH.jpg) These things live everywhere, including the desert. You could have your alien versions wear flowing Bedouin like robes. Even better, though, would be for them to go naked except for very large and light sombreros. ]
[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/94579/edit). Closed 6 years ago. [Improve this question](/posts/94579/edit) After an apocalyptic event (worldwide weaponized plague knocks out 90% of the population, say), what city in the U.S. would make a good sanctuary for survivors and the new capital for the remnant government? I'm thinking proximity to natural resources, plenty of hospitals/research facilities for finding a cure, possible nearby space for farming or biodomes, and defensible, if possible, to keep out undesirables (relatively easy to monitor entry and exit points, set up checkpoints, patrols, maybe some kind of electric fencing). [Answer] Perhaps the best option for a post-apocalyptic sanctuary will be well away from the most obvious cities. A weaponized plague (dirty bomb sort of thing) will almost certainly be focused on Western Europe, Russia, Eastern Asia and the US. In the US, this means major centres like DC and NYC, Chicago and LA will be prime targets. Major US cities will be targeted and probably struck multiple times and will most likely be uninhabitable for quite a long while afterward. With a 90% reduction in population, the remaining 10% will not be able to keep the infrastructure intact or functioning. Power systems will fail, utility systems will fail or be destroyed in the attack and in subsequent weeks to months. Clean up will be nearly impossible. Keep in mind: DC can barely clear a half inch of snow from the streets without becoming totally paralysed. How well do you think the region would do with an entirely wrecked infrastructure? This leaves Alaska and Hawaii as two remaining possibilities. Alaska is isolated and Anchorage would be relatively easily defended (undesirables from the lower 48 are unlikely to try the long trek north). Farming may not be so easy, but in a post-apocalyptic world, fishing should be able to provide adequate nutrition. Plus Alaska has plenty of oil. It's not so robust in the medical research arena, though. Alaska will be an unlikely target for plague weapons, and normal wind patterns should keep all the nasty bugs down south. Hawaii is perfectly isolated and also represents an unlikely primary target of attack. Prevailing winds will keep it safe from all the discharged weapons unleashed on the continent; its distance from Asia will keep it relatively secure from such weapons used in China, Japan and Korea. Hawaii is relatively easily defensible: again, the survivors from the mainland will not be able to swim to this sanctuary. Hawaii is more amenable to agriculture, and fishing is also a viable resource. There is a medical research presence in the islands. Hopefully they will simply turn away the carpet bagger "remnant government" as the troublemakers they are. Restore the rightful monarchy and join forces with Alaska. Together, they should do pretty well as a sanctuary for future civilisation! [Answer] This question is so broad that you could write a book about it. I know because I've read a books about it. And the short answer is: any city as long as you don't need water, food, or resources to live. The long answer is: there is no such city. You need water (all cities have mechanical pumps to pull water from water supply), you need food (all cities are asphalt jungle and if you don't eat dandelion you have nothing to eat), you need resources (and although it may seem that there are plenty of them in the city they would be salvage). Also the environment of city would be destabilised by the sewage, wild animals running free (the ecosystem of the city is not prepared for feral dogs) and things would fall apart without proper maintenance. In the open you can start easily, excavate the well or settle near a river or a brook. Materials and resources could be available on the site (ever heard about the wood?) and growing own food is a matter of either seeding it in spring or hoarding and replanting in greenhouse or field. You have Maslow pyramid of need and without food, sleep and shelter you cannot push your research. Also your R&D facility would need easy to maintain self sufficient power source. So any that don't have it's own wind/sun/geothermal generators it's useless. [Answer] Yellowstone National Park. Isolated, lots of natural resources, plenty of water, not likely to be a military target. And certainly not the area you would expect survivors to flock to. Very few roads in. Probably not an area that would harbor a plague (few inhabitants). I can assure you, the very LAST place you would want to be, is where all of the victims would flock to - the hospitals and medical centers. There would be so many dead bodies lying around, the plague would be the least of your health worries. If you survived, you probably have immunity to it, but probably not to all of the other diseases that would surround ANY medical facility. And forget about any hope of resurrecting the glory of the United States of America. You will be too busy just trying to survive. There will be absolutely nothing left to be patriotic about. It will be the first nations people that are the most prone to survive in such a land, and they CERTAINLY will not want anything to do with resurrecting America. [Answer] While it is probably not the answer you are looking for, because you asked a [shopping question](https://stackoverflow.blog/2010/11/23/qa-is-hard-lets-go-shopping/) and I'm not going to give a shopping answer. I'd say: # Relatively small city or big town, with destroyed airport Really, if this is about weapon-plague that went pandemic, then you can expect that all cities with airports will be infected in the first waves. Even if your plague is not contagious when victim is dead, you do not have manpower to clear the dead from the streets and apartments, and soon you will have regular plagues there. So you need a small city that simply could not be infected. Also, you need it small if you want to ever have hope to set up a fence and really patrol your perimeter. Last but not least, you need a big supply chain for big cities. Dedicated drivers, good roads, villages nearby. To avoid that need, your place needs to be small. Towns appear "because there is only so much fields you can have before you need something else"1, so land to have crops is something that will be there. # You need armed men who knows what to do To set up quarantine, you can't just give guns to citizens. You need trained personel. So towns and cities with **military bases** are your friends. Military may be the reason why airports got destroyed, too, if local commander thinks fast enough. # You need electricity And without industry, you probably will have to go with hydroelectric dam. Natural gas turbines may be a way to go, too. # Research facilities This, sadly, conflicts with small, no airport etc. CDC headquarters is in Atlanta, Georgia. Associated research facilities are in 26 cities, but only big ones. Medical schools and universities strong in biology are something that gives hope. --- So what you need is: * a town / small city that: * has no airport (or small traffic airport and someone smart enough to blow it anyway) * has a military base nearby * campus * hydroelectric or natural gas electricity Knowing that, you can take a map of any continent / country / area you need and then just pick one. **It's a plague, luck is more important anyway**. Conditions above merely increase chances from *next to nonexistent* to *slim but believable*. --- 1 I recall reading this in one of Pratchett books, but when I look on a map or read urbanization history, it looks true enough. [Answer] None of the above, not straight away, any large population centre will be a hotzone of famine, plague and violence during the apocalypse, what's left is probably not going to be *habitable* for a while after that. In the long term ironically the worst hit cities in the early days and weeks are probably going to be the best long-term investments. Cities with large highly built up cores are going to be the worst places to be during the collapse of civilisation, but the wide expanses of concrete buildings will form fire breaks against both actual fires and also the encroachment of returning vegetation. Several factors to consider when picking a particular setting are the availability of arable land in proximity, water supply and geographic security; for example Portland, which has been described as the perfect post-apocalypse location, has good farmland on three sides, and a gravity fed water supply but Mt Hood is within 50 miles of downtown so geography is not really on your side. Boise is slightly more secure but the farmland is less productive, Manhattan is solid bedrock but you can't farm it, D.C. will largely flood, ditto New Orleans, Miami etc... It's all a balancing act, one thing you may or may not need to put into the equation is what I'll call "industrial legacy" this is about both equipment/facilities that can be reactivated but also about toxic materials that may be left behind, taking that alone there are places, like Love Canal or even Pittsburgh, that are immediately off the table as too dangerous. My personal pick would be Sacramento, good water especially once the L.A. Water Scheme Pumps shut down, good farming in the central valley and the inland delta, and while earthquakes are a risk you can build to accommodate them more easily than with a volcano. ]
[Question] [ In a land where the majority of people have multiple personalities, how do the personalities distinguish themselves? Whenever they change personalities, they have an immediate need to disassociate themselves from their alternate personalities, and it is not practical to change clothes. Not only that, but it is not enough to demonstrate through their actions that they are different, or to have a numerical or nominal identifier, they feel a pressing and impulsive need to demonstrate their individuality, and the fact that they are not merely another iteration of the same person. Unfortunately, most of them cannot shapeshift, so what sort of clothing items would they trend towards, that the style can immediately be altered easily, with enough of a visual distinction to satisfy them? [Answer] While it is not practical to change clothes, there is a simple solution. and it is one that has been implemented already. Reversible garments. Garments of this type are usually soft and flexible. Shirts, T-shirts, jackets, trousers, even caps, and, of course, the ladies will have reversible blouses, tops and skirts. With each change of personality the person will turn inside out the appropriate part or whole of their clothing. Let's take a simplified version of clothing changes to match changes in personality. For example, if the citizen changes from personality A to personality B they might turn inside out their white jacket into a black jacket while leaving the rest of their clothing unchanged. Let's assume personality A wears all white and subsequent changes will be reversing garments from white to black. Further changes of personality, then the trousers might be reversed, next the shirt, the cap can be changed too. This reversible clothing model allows for a reasonable number of combinations of different coloured clothing to designate different personalities. Alternating between black and white is very simplistic. Multiple personality citizens in this society might use colour coding as a way to signal what personality they are currently expressing. If the personalities have different psychological dimensions expressed to a greater or lesser extent, then it may well be that people wear specific colours to designate, say, how extraverted they are compared to their introversion. You might want to develop a colour scheme to represent the different psychological dimensions. Then changes of clothing, using reversible garments, if the colour scheme is incorporated, then this can be a way of sending a message of which personality is being expressed by the citizen. This would be a dual method for emphasizing the individuality of that specific personality. [Answer] **Scarfs or bandannas.** Easy to carry several different ones for signaling a change. Other jewelry or decorative trinkets can also be horded in pockets to be displayed only as needed. Color, pattern or position can all be cues about the personality. **Simple wraps.** A piece of fabric can be draped around the person in a distinctive fashion. I'm sure I've seen dozens of toga patterns from a bed sheet, neck tie knots have an unbelievable number of variations, and turbans also seem to offer similar variability. With clothing designed with this in mind options could be pretty diverse. On a change you get dressed all over again, it just uses the same piece of clothing. This can even be fairly subtle, since if it's a common thing people would get adept at identifying it. Some arrangements might be difficult to make or even maintain for someone who hasn't practiced limiting the ability to be copied by other personalities. [Answer] In the land that your describing, this is a commonality among most or all of its inhabitants, so perhaps the answer can be found in your land's social structure. Perhaps there isn't a need to carry or have certain clothing with them because in this world there are areas, as common as bathrooms in our world, that anyone can go into and change their wardrobe as needed. Since it's a need felt by nearly everyone, it's not a stretch to think that society would have come up with a way to accommodate that need by providing changing areas that give an assortment of clothes, and some way to easily use them (maybe even some paid, some free but with limited selection. Could tie into status.). I'm not sure of the technological advancement in this land, but that could determine how elaborate these areas are, how they are shared and used. In fact, taking this premise one step further, maybe ownership of clothing in this land is a little more fluid since people have a need to change clothing with their personality, when they go to these changing areas it's easy for them to give up their current clothing in exchange for something that suits them because clothing isn't something that one permanently owns. There are many ways this concept could be used and modified if it suits your needs. [Answer] In [Nobody's Perfekt](http://www.imdb.com/title/tt0082822), “whoever gets up first gets dressed”. However, nobody had any problem telling which alter was present, and having one alter dressed as another was a running joke. Point is, they (and the audience) easily distinguished who was in the light, and *then* ascessed how that character was dressed. Not the other way around. So clothing may be more generic, even across different cliques: everyone dresses alike, *not* personal style. A specific accessory might be unique to each personality, like a colored pocket square or scarf. That is compactly stored and easily switched. [Answer] This answer proposes the simplest possible change to a person's apparel and to distinguish their different personality (different from their other personalities), Namely, the name tag. This does, however, assume the different personalities have different names, but under the circumstances of such a multiple personality society that does make a certain amount of sense. [Answer] In a society where multiple personalities are accepted and understood it absolutely makes sense to have a code to identify who is currently occupying the conscious thought of that body for other people, so it seems there are a number of solutions. How many personalities do we need to cover? -- reversible clothing, generally- either flip to expose a new material, or rearrange into something specific to your personality (draped robes, cravats, scarves, belts...) -- distinguish between colors or patterns, where personalities have signature looks- this could mean Bob always wears a red shirt, or Bob wears bright solids with dark pants, or Bob always uses the plaid handkerchief as a pocket square or armband. -- if your society is technologically advanced you could use smart textiles that change color based on an electrical stimulus, or use fiber optic fabric with light sources along the seams-- this could be fantastic camouflage, too! -- have a customary device, such as an LED lapel pin with a certain display color, or even a programmable nametag, or a mechanical pin/necklace where most colors are hidden in a sleeve, but holes show a specific color until the colored inner part is adjusted to expose a different color, or having pieces that flip up or could be configured differently. These could get quite decorative or gaudy, like large jewelry pectorals with a counterweight flap on the back, identifiable from all sides. [Answer] **Wraps around the torso area** The wraps should be distinctly different colors and also have a number to signify the current personality. If every person only had one name, this would be even more significant, but if every personality was given a different name the number could signify the amount of personalities the host held. This would make it significantly easier to know what people were getting into when making friends and relations. It would also be very useful if the wraps where also always pulled taut, making it easier see the color from long distances, so that shadows would not mess with color recognition. [Answer] Slightly silly, but hats and cheap sunglasses or other eye-wear. When you look at someone your eyes will seek out the eyes of the other person. When you look in a mirror, you will likely find yourself looking into your own eyes first until you shift focus to whatever you are looking at yourself in a mirror for. Right above your eyes is the top of your head, and you take that in as well. Each personality has 1 hat and 1 pair of glasses. Swap them out when the personality changes and you will dis-associate yourself from the previous personality just as soon as you look in a mirror. [Answer] I was thinking face-masks. People usually focus in on the face when identifying somebody definitively, which means a face mask will be front-and-center when it comes to identifying people. Additionally, if people are very against being mistaken for other people, than focusing in on the little identifiers (clothes) is probably less effective than addressing big identifiers like *having the same face*. How would it work? I would guess cloth face masks, since they will be more comfortable to wear long term and light to carry. It would also be pretty easy to personalize, too, between cloth choices, embroidery, and other decorations. They don't have to be full face masks, either, choices among partial masks can be an additional layer of identification, with one person preferring a full face mask, another just an eye mask, and a third a mask over one side of their face. And one pocket or pouch full could carry a lot of masks, for a person to change into. Culturally, the mask would then be your "face" in a way skin-and-bone would find problematic, when bodies may be shared among so many people. It would be no more abnormal to them than us wearing other kinds of clothing (or identifying things about people from such). There could be a set meaning to going bare-faced, like signalling changing personas, or it could be a privacy taboo, where people do not bare their faces without a very good reason and perhaps people would keep a blank mask to have something to cover their face with if something happened to their personalized one. If, for whatever reason, it is important to identify people form behind or without seeing their face - it may be useful to pair with scarves or shawls. I mean the light, thin ones large enough to drape (easier to carry multiple, then), possibly reversible to maximize the number of variations for less cloth carried. Color plus pattern plus wearing habit (tied shoulder-to-hip, draped around neck, wrapped around shoulders, as a belt) can again individualize a person pretty distinctly without seeing the face and without having to make elaborate changes. I think it would still be best paired with masks, since it's easier to notice differences like sash or scarf when not using the same face for identification. [Answer] In a society were everyone has this need everyone would be looking for the standard societal signals as to who someone is. If this is true then wearing pins on your cuffs would be enough. ]
[Question] [ I'm posing this question in the terms of inbreeding depression and hybrid vigor. It probably depends on the size of the inbreeding population, and I'm making supersoldiers in a pre-industrial society, so I think I would be satisfied with 100-300 men... er, that would make 200-600 people. It also seems to me that at a certain point it only makes sense to take in women from the general population, because only men can be soldiers (pre-industrially speaking) and they get so badass that men from the general population couldn't keep up with them in training. Does this make sense? In other words, would taking in healthy girls for breeding be a thriving industry, or would that be a situation of "the chosen one", or a completely secluded compound, or something else entirely? [Answer] Your question states that this eugenics endeavor is one of inbreeding, and that is the fastest way to maximize the prevalence of the traits that you want. From <http://onpasture.com/2014/10/20/breeding-matters-iii-inbreeding-vs-line-breeding/> "Interestingly, before the advent of genetic testing for recessive traits the only way to statistically ensure genetic “purity” of a bull/ram/buck etc. was to breed that bull to 35 of his own daughters concurrently. If no genetic defects show up in any of the offspring, the bull is 99.7% likely to be genetic defect free." Your project will require a lot of incest and a lot of culling. I found this interesting; from <http://bowlingsite.mcf.com/genetics/inbreeding.html> as regards all matings being brother - sister crosses: [![enter image description here](https://i.stack.imgur.com/hzeSQ.gif)](https://i.stack.imgur.com/hzeSQ.gif) "The figure shows how the inbreeding coefficient chages with generations of brother-sister matings. As a general rule, this type of mating in domestic animals cannot be kept up beyond 8-10 generations, as by that time the rate of breeding success is very low. However, the rare survivors may go on to found genetically uniform populations..." Thinking strategically you might not want to commit the entirety of your breeding population to the project because your population will crash because of inherited diseases. If there are any survivors after that crash those could be your super soldiers. I can imagine that these super soldiers are a religious project of the society: breeding brother to sister, culling the unfit etc. The end result of your super soldier project would be that your super soldiers and their sisters / wives will be genetically identical: a stable lineage free of inherited diseases with predictable characteristics generation after generation, just like an inbred strain of lab mice. *This super soldier thing proposed here is grounded in genetics but is appropriate only for a work of fiction.* The bowling site article notes that the ultimate phenotype of a stably inbred strain has a lot to do with luck and that it is very difficult to control exactly which genes these stable strains has. So the prospect of actually pulling off a breeding experiment like this in real life (human or otherwise) seems slim. If it could be done it would be a great thing for popular dog and cat breeds; the fact that these breeds still suffer from genetic diseases suggests to me it is not an easy thing. [Answer] If you want a historical answer look to Sparta. At birth, any "imperfect" babies were tossed from a cliff. At age 7 male children were kicked out of the village and lived like animals in the outlying areas, fending for themselves, stealing, and forging bonds with older boys. At 14 they are allowed to return to society by surviving a gauntlet of the whole village beating them while they try to steal cheese, then the real training begins. It's estimated the Spartans weeded out their own men down to only the "top" 30%, or in other words only 3 in 10 boys survived to adulthood. The ironic part is that [Spartan women](https://en.wikipedia.org/wiki/Women_in_ancient_Sparta), while not given the same harsh treatment, do not cower from these "supermen" but instead [all turned out to be ballbusters](http://spartareconsidered.blogspot.com/2012/12/only-spartan-women-give-birth-to-men.html) who filled in the various vacant roles in their society. Although not treated as equals, the women exercised along with the men, and ate the same meat as the men, and at least in some cases owned property, horses, businesses – this was unheard of in the rest of Greece. Although not allowed to directly compete [a Spartan woman sponsored horses in the olympics](https://en.wikipedia.org/wiki/Cynisca). And the most flagrant display of female independence in history was by a Spartan Queen named Helen of Troy. Any breeding program to create superior men would eventually consider the superior women that birth them (and they might actually take pride in it). Grabbing random women off the street seems to be at complete odds with eugenics, not to mention a traumatized unwilling virgin mother doesn't sound like a healthy baby factory. I suggest more women than men in your program (at least double), with possibly a lot of brainwashing over how healthy and fit they must be to provide babies for the cause. They would be kept separate from the men, or rather the men would be kept separate from the women for reasons any farmer knows. [Answer] Women determine the genetics and prenatal environment for the children--that's actually a BIGGER contribution than what the males can do. They only give 1/2 the genetics. So, what do you do with the girl babies produced? Keep track of them. Maybe even let them back into the general population to interbreed. And then their children might have a chance to be part of the breeding program. You can have specific requirements for the women who are allowed in--especially first generation ones. Because it's pre-industrial, genetics won't be known. But breeding will be...so it's likely that they will track relations, and track those who score the highest on whatever scale you're rating them on. Anyone talking about genes, shouldn't be, because these folk won't have any idea what genes are--they'll just be tracking characteristics. Even Mendel, who began to understand, is actually at the dawn of the Industrial age... > > The Industrial Age is a period of history that encompasses the changes in economic and social organization that began around 1760 in Great Britain and later in other countries... [SOURCE](https://en.wikipedia.org/wiki/Industrial_Age) > > > So, depending on the country, we are looking at early 1700s. By this time, we had been breeding farm stock, dogs and other domesticated animals [selectively](http://wallace.genetics.uga.edu/groups/evol3000/wiki/ce8b9/Selective_Breeding_or_Artificial_Selection.html). The same can be done with humans but it take longer because we reproduce not so quickly compared to, say horses, which can be bred in three years... [Answer] What wetcircuit says. Sparta is a good example. Adding to that. You want your women to be fit. Childbirth at that technological level is dangerous. You want them to survive. Add to that the slow reproductive speed of humans, about a year per child. You can easily have more women then men. A single one could impregnate multiple women. It's gonna be slow though, well over a decade between birth and reproduction. I assume this will be coupled with a heavy training regime much like the Spartans? Grabbing women from the Streets would be counter productive. You would pollute your genepool with random genes. They're untrained and you'd lose many during childbirth. Very inefficient. ]
[Question] [ On its mission to explore new worlds and seek out new civilisations, the spaceship 'Exciting Undertaking' came across a planet of seemingly unadvanced aliens. Following their First Direction (forbidding interactions with pre-wrap-capable aliens and *totally not* modelled after anyone else's rules of interspecies interaction), they spied on them from orbit and then left. Little did they know that the species below were actually a race of highly advanced space wizards (people with enough technology that they may as well have been magical) who had abandoned any technology that couldn't be understood with a rudimentary understanding of mechanics (for undisclosed reasons *totally not* related to accidentally ending the universe once or twice). The question is how the space wizards (who were clearly intelligent and curious enough to have become space wizards in the first place) managed to suppress their populace from trying to advance beyond renaissance levels of technology over immense timescales (the kind of timescales where facts become ancient history, ancient history becomes myth, and myths fade into obscurity). Bonus points if your method of suppression also gives the space wizards a way to migrate to another planet when their current home nears it's natural end; without them becoming curious about how it was achieved. **Edit to constrain the questions more:** The space wizards were a Kardashev type III civilisation with high levels of control and information processing, leading to them having the ability to cause any physical phenomenon that isn't physically impossible. While very powerful they can't necessarily guarantee that their technology is infallible, and long term systems could break down if not suitably maintained. Now they have no technology that can't be understood (or at least copied) by looking at it and studying it with macroscopic tools, so no microprocessors, complex balanced chemical reactions or electrical devices. If it requires more than a few minutes of explanation it's a no-go. Forging and simple mechanical devices such as bellows, water wheels and gearing are OK, but further scientific and technological endeavour *must* be discouraged to reduce the chance of ~~totally awesome~~ potentially devastating repercussions. If you're wondering about methods by which the answers to this question will be weighed against each other: **Likelihood of failure:** How likely the space wizards are to throw off the shackles and go forth to once again almost blow up everything. **Longevity:** How long this suppression is likely to remain in place before suffering catastrophic system failure. **Ease of implementation:** How much effort the original space wizards would have to put in in order to put this system in place. **Rule of Coolness:** More of a jokey (hugely subjective) category, but we all know that cool things work better in space. [Answer] > > How they managed to suppress their populace from trying to advance beyond renaissance levels of technology > > > Of course, to do that you need technology. Technology so advanced as to be indistinguishable by magic. Technology requires energy, so one way of doing this could be to monitor the energy density over the whole planet; whenever it exceeds some fixed point, siphon it off somehow, or call in a KEW strike from orbit. The first is better, otherwise some smart guy will develop the Tech Bomb - instead of mixing nitric acid and glycerine, you pour alcohol *inside a piston*. This creates an internal combustion engine, and next thing you know, eveything all around has been blown to smithereens. If instead the piston went *pffffft!*, this ought to deflate the inquisitive spirit of most wannabe alchemists. For our next hurdle, we also need to cheat. *Teleportation*. Except that you have it *all the time*, and don't think anything special about it. It's the way of life. You enter a door, you are in the room beyond; you enter a Portal, you're somewhere else that's much like where you started. Mountains, grass, rivers. Sometimes colder, sometimes warmer. So after several years of cold winters, more and more people build their homes half a mile eastwards, across a Portal. They don't know and they don't care that the new place is actually three thousand miles south of the first - to them, it's half a mile. Comes handy because the weather is different, and you can escape a storm by crossing a portal. Wise farmers will keep fields on both sides, and this might even become a proverb. And when the Sun begins to cool, they'll seek warmer and warmer portals - and what do you know, one of them not only has different weather, the *Sun* seems slightly different too. And the sky at night. No big deal, huh? [Answer] I can imagine three approaches to this. **1. The secret cabal suppresses technological development** In this scenario a secret group of ruling elite still have access to technology-indistinguishable-from-magic. They use it to monitor the developers of technology and anytime someone starts to investigate an undesirable tech, they use mind control/teleportation/break physics to mess up the experiments/experimenters. **2. The environment has been tampered with** When the non-wizards from space realized technology was bad they set about permanently modifying their planet(s) to avoid future technological development and then destroyed all records and examples of said technology. They eliminated fossil fuels, dispersed major ore deposits, and introduced air born bacteria that attacks all forms of paper. Suddenly science and technology are so difficult that advances have a hard time surviving long enough to be capitalized on. **3. Cyclical disasters** Some kind of world wide inundation, firestorm, or epidemic occurs on a roughly 1000-4000 year period. The world's population is so decimated by each disaster that it sends them back to the stone age. Brutal, but effective. [Answer] > > Religion > > > If you can somehow create a book which tells the story of a deity which is all-powerful, all-seeing, and all-loving, and document the ways in which said deity has been involved with the history of the species, it is possible that they may worship said deity. In this religion, electricity is a power only to be used by the deity themself. Anyone found to be using electricity will be smited from the heavens! Of course, the space wizards who are particularly high up and know of this plan will take the role of the deity, brutally murdering any and all users of their powers of electricity. This way, the race will remain in a state where they cannot use any technology other than steam power, and every once in a while the deity will perform a 'miracle' and an ark will appear to take the people to the holy lands. Once at the holy lands, myths of the previous world will fade into memory, and most will argue that it never happened, since an ark such as that has never been seen in living memory! Perhaps a small sect will break off and say that in fact they have not reached the holy lands yet, and in fact the book tells us of the future, not the past. Rinse and repeat. [Answer] (A) "Kardashev type III civilisation with high levels of control and information processing, leading to them having the ability to cause any physical phenomenon that isn't physically impossible" will simply use mind control to suppress any unwanted technological development. Admittedly the OP hasn't explained how or where the space wizards have concealed their Kardashev type III technology. Possibly, this gives the OP and the apparently incompetent sensor operators the spaceship *Exciting Undertaking* a way out, the space wizards are capable of high-level concealment or what constitutes Kardashev type III technology is utterly unrecognizable to mere primitive space crews. The local population would be mind blocked from recognizing it anyway. Now to analyse the OP's answer criteria ***Likelihood of failure:*** How likely the space wizards are to throw off the shackles and go forth to once again almost blow up everything. There is one problem here. A contradiction between the space wizards being struck at Renaissance level technology and maintaining the populace in retro-technological subjugation. This once the system was set up it was left running on auto-pilot. if there are some space wizards who know what is really going the temptation to go full-blown Kardashev type III civilisation will be overwhelming. It could happen at any time especially when a bunch of nosey parkers, for example, in the spaceship *Exciting Undertaking* turns up. ***Longevity:*** How long this suppression is likely to remain in place before suffering catastrophic system failure. As long as some random or unexpected event doesn't tip the balance. Anywhere between five minutes and five billion years. It is to be expected that normal astronomical events going red giant, nova or white dwarf can be fixed by a Kardashev type III civilisation. ***Ease of implementation:*** How much effort the original space wizards would have to put in in order to put this system in place. Presumably this was a former colony planet of a Kardashev type III civilisation and they subtly processed colonists as they arrived. The result would be a full blown Renaissance civilization with a bunch of space wizards pulling the strings. Unless the space wizards want ed to go Renaissance level too. ***Rule of Coolness***: More of a jokey (hugely subjective) category, but we all know that cool things work better in space. Cool enough, but not too chilly. Does seem strangely like a typical of those guys and gals who used to go boldly where no person had boldly gone before in their split infinitive hyperdrive. Answer: Simple, straight forward mind control. Why bother with anything complicated? They're Kardashev type III technology level space wizards, so what could be easier? ACKNOWLEDGEMENT: Thank you to the late Peter Dickinson for inspiration for this answer. [Answer] I'm going to answer your question with a question: Why do people develop technology? Generally speaking I would say, they do it to make their lives easier, to accomplish a needed or desired task with less work. (Another possibility is general curiosity but this could be handled in many ways) If your renaissance level tech world has nano-super-tech-magic to effectively meet the peoples needs or any possible desires, I would say there is going to be very little motivation to develop "lesser" technologies. Who needs a steam engine train when magic wagons or teleportation can move goods cheaply and efficiently. Who needs a computer or internet, when the magic mirror oracle can answer any question and farcasters can let you talk to distant peoples. Who needs big hospitals when the local wizard's potions can cure all diseases and mend all wounds. Who would want to live in a crowded megacity, when small hamlets or the occasional small city make for much nicer places to live. As for the curious people, these sound like great people to make into future space wizards, allowing them to research and play with technology in their nicely controlled simulations or pocket dimensions where it doesn't bother any of the neighbors. [Answer] Why would an advanced civilization suppress the very technology that made them advanced? The very drive to advance insures that such a civilization won't stop. In your theoretical world, a leader might order such a restriction, but the technologists will figure a way around that. They always do. More likely, they'd be using tech that was beyond the ability of the visitors to understand. Might not even be visible to a lesser civilization. They've come up with personal warp devices, that they can teleport themselves anywhere without needing something crude, like a space ship. Or, their tech has evolved to the point where they can live in harmony with the host planet. So this wouldn't be a matter of no technology, more such an advanced tech that it doesn't interfere with their surroundings. [Answer] The space wizards are not consider humans but either gods or some kind of human/spirit hybred. It is there belief that ordinary human can not understand much less recreate the technology. So there might be curious but since they have no hope that they will ever understand so they do not see the point of trying. To maintain the allusion all the technology of the space wizards are sent to there genetic code, using it without the proper genetic code will result in it exploding and harming the user so even if your average peasant decides to let his curiosity get the better of him at examines the space wizards tec a little too closely, then he will die and the story will become a cautionary tale to convince the others the danger of been too curious. This method will by law of natural selection decrease the amount of curious people. And when it becomes time to change planets, surely the powerful space wizards our capable of men in black level mass mind wipe. So every time that move to another planet the wipe there minds and teach them from scratch. this will further hinder and technological development. 1.Likelihood of failure: very likely unless the original wizards who came up with this method are immortal, then I give it a generation maybe two. 2. Longevity: Forever as long as they do not encounter another space faring civilization. 3. Ease of implementation: A lot at first but after a thousand years or so the hole system become self sustaining. 4.Rule of Coolness: i created it so yes it is very cool [Answer] They genetically engineered their species that individuals do not understand physics involving more than 3 dimensions. Furthermore, they all have ADD (which is not a disorder, in this case, it is a way of life). When they need to solve a complicated technical problem, they join their minds into a hive mind, which is easily capable of solving any problem in any dimensions and can instruct its members to fabricate the parts they need to put it together, and completely destroy everything after the problem is solved. Not that they need to, as once the hive is disconnected, individual members will be incapable of a) understanding how to use the fabricated device and what it even does, b) simultaneously (down to the microsecond) pressing that many buttons. If just one member of the hive has a moral problem with the solution, this will propagate through the nodes and instead of solving the problem, the hive will be occupied with working out the morality of whatever they are trying to do, and as the species consists of highly opinionated members, this could take many years - potentially longer than the problem exists. (They do still eat and sleep and maintain the resources needed for their society to continue existing while they are doing this.) [Answer] Mind control. If you have effective mind control of some type, otherwise absurd situations suddenly become possible, and once you have a situation set up, it becomes self-sustaining. So, they decide they need to go to Renaissance-level tech and not advance any more, but they need the advanced tech to ensure they stay at the low level. Everyone gets mind-wiped and without the curiosity or desire to technologically advance except for some caretakers of the minor amount of advanced tech necessary who are themselves mind-woogied so they don't exploit the situation. You could have a situation where there's a revolving set of caretakers who are selected, given the mental upgrade to be able to maintain the tech that keeps the mind-control working, and when they're done their "shift" they're manipulated into forgetting all about it, or it's altered into a vague religious-like experience, and their disappearance from their home towns chalked up to a religious pilgrimage or whatever. [Answer] I would go with destroying all sources of stored energy. Burn oil and coal in the ground, dissipate uranium in the sea. Make iron sources few and far between. The main difference between early-industrial and renaissance technologies is usage of fossil energy. No fossil energy, no industry. [Answer] > > The question is how the space wizards managed to suppress their populace from trying to advance beyond renaissance levels of technology over immense timescales > > > Traditional government stuff, such as making and enforcing laws to perpetuate the monopoly, killing and imprisoning dissenters, and giving people something enjoyable to focus their attention on. There's plenty of examples on this very planet of people successfully suppressing innovation. Population control. Most innovations take single people making incremental advances, and if there's only 10,000 people on the planet for 10,000 years, it's extremely unlikely random innovators will slip under the radar. Kill those who do. Language and cultural obfuscation and diversification. In order for large groups of people to get to together and create innovations, they need to have a set of shared assumptions and language. If you force all your tribes to be so distinct they can't communicate, and they aren't trading or otherwise interacting with each other, they will never work together to accomplish technological innovation. Just purge the ones who do. > > Bonus points if your method of suppression also gives the space wizards a way to migrate to another planet when their current home nears it's natural end; without them becoming curious about how it was achieved. > > > During the migration process, tell everyone not to look up. Immediately murder anyone who does. Also, people don't need to have things hidden from them to not care about it. Billions of people every day use things like bar scanners and cars, but they have no idea how they work. Suppressing the witnessing of technology isn't necessary to suppress technological advancement. An extremely tiny number of those billions of people using cars and bar scanners are ever going to take an interest in either cars or bar scanners, and an even smaller number of *those* people would have the chops to innovate either of those technologies. Through most of history, the percentage of real innovators who have pushed technology forward is incredibly tiny. And the smaller the population, the easier it is to suppress ideas. There's plenty of traditional population control methods could keep people in a type of state. ]
[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/69643/edit). Closed 6 years ago. [Improve this question](/posts/69643/edit) Bill has a special power: he can create any kind of sensory hallucination on anyone that gets near him (about 1 km range). The hallucination can be as complex as he wants it to be, and it doesn't require him to pay attention to its victim (it can be a completely passive effect, like making everyone see an empty bed instead of him sleeping). Assuming no sniping (he lives in a city so there is no way to get a clear sight on him without entering his powers range) and no carpet bombing, what would be the best way to kill (or at least capture) him? This is fairly similar to [Assassinate a semi-omniscient crime lord](https://worldbuilding.stackexchange.com/questions/68481/assassinate-a-semi-omniscient-crime-lord), but there are a few key differences: 1. He's not omniscent. He doesn't know how many people are in his powers range, or what they are doing 2. He can only act directly on those that he knows are there. If he doesn't know someone is near him, only his passive powers work 3. He doesn't have huge financial capabilities, though he could trick cops to protect him with some complex hallucination 4. As soon as he notices someone, he can make him visualize/hear/percieve whatever he wants EDIT: everyone is assuming he's a villain, but he's not. He just wants to live a normal life, but is chased down by the government/special forces, and has to resort to self-defense tricks like making himself invisible to everyone but those he's talking to. [Answer] ## Use a discreet drone A drone can be operated from more than a kilometer, it doesn't get hallucinations, it can carry weaponry/explosives/gas and can stay unnoticed until the last moment. ## Get his trust Bill can influence people's perception, but he can't know their intent. As you can't stay alone your all life, everybody needs some sort of companionship. Someone attractive and a dose of poison is all you need! [Answer] # His power only works while you're in range. Bill is human(ish), Bill presumably wants to live some kind of life and leaves some kind of trail if special forces are after him. Perhaps he likes living in one area, perhaps he occasionally has 1 night stands with people he meets at a few clubs, whatever. We can assume he's not a total ghost. **Bills power does not work on video cameras.** So, stake out the locations that you think he might be, push everything through video cameras and have people a few miles away watching the footage in real time. He's also visible on public CCTV so he can be tracked. If your goal is to kill him simply wire his home up with explosives and video cameras while he's out for a walk. When he walks in the door verify he's the target and hit the button. If bombing is not practical then alternative options include poisoning his cheerios, gassing him or filling his socks drawer with scorpions. **Simply killing seems a little to easy** There's even the option of flooding the room with riot foam if you want him probably-alive. [![riot foam](https://i.stack.imgur.com/WaiPY.jpg)](https://i.stack.imgur.com/WaiPY.jpg) **Capture** Concealed canisters jet riot foam in every direction covering Bill. A speaker comes to life and informs Bill that if he does not comply there's a second, lethal trap that will be triggered. They are watching him on camera, he must not use his power and must allow agents to enter and place a collar on him. He is being watched by many cameras. The collar includes cameras, tacking and an explosive charge that can be detonated by his handler who is several thousand miles away. The special forces just caught themselves an agent who can walk past almost any guard post who can be managed remotely. [Answer] Based on 1 and 2, he can only act on people that he knows are coming for him. He lives in the middle of a city, so there are thousands of people around all the time. Someone that is trained in observing without being noticed would be able to keep tabs on him, observe his routines, and get close enough to act fairly easily. Unless the guy is paranoid enough to go around without being seen constantly, he's going to be vulnerable to people just walking by him. As long as they don't draw attention to themselves they could brush by him in the crowd, give him an injection to knock him out, tie him up and take him to a lab or whatever. [Answer] # Give him a choice If he's not a bad guy, don't try and kill him right off the bat. Get him to talk to you and get things sorted out peacefully. If he doesn't trust you, then use containment and evacuate the city. Place remote controlled gates around the perimeter and ask everyone to leave the area for their own good. Once he's the only one left, feel free to send in a heat-seeker equipped drone and zap him with tranquiliser darts. Whatever choice he makes, lock him in a room with a 1km gap between him and anyone else and serve him his meals on a model train.... [Answer] One of these. Control it remotely. Kill him or capture him with it. [![enter image description here](https://i.stack.imgur.com/izPxR.jpg)](https://i.stack.imgur.com/izPxR.jpg) ]
[Question] [ We don't have a pill that can serve all of our nutritional needs, but we do have soylent, which supposedly takes care of the nutritional needs for a person ( and is reported to taste quite bland). There are a plethora of dry pellets in the pet aisle that are specially made for each type of animal consuming them, each containing different ingredients for the animals they were made for. The closest thing I could think that we have to "Human pet food" is cereal. If such a food were created I imagine It would be like ramen in the sense that it would be cheap and you could survive on it for a while Is it possible for there to be generic food pellets made for humans in a variety of different flavors to serve as "human pet food" and supply our nutritional requirements and if such a food were created what might be the impact? [Answer] # All-in-one human foods have existed for thousands of years [![enter image description here](https://i.stack.imgur.com/2dKYP.jpg)](https://i.stack.imgur.com/2dKYP.jpg) [![enter image description here](https://i.stack.imgur.com/6w7Yu.jpg)](https://i.stack.imgur.com/6w7Yu.jpg) People survived on these staples (as in 80% + of their calories came from bread or rice) for most of recorded history. 2000 calories of either comes with all the fiber and most of the protein you need (both being notably lysine deficient). To make up the gap (and fortify all those vitamins and minerals), just add a few sunflower or sesame seeds, and crush up a vitamin pill in it. Done and done. As for variety of flavors, you can put jam on your bread, and soy sauce or sriracha or whatever on your rice. Humans have been eating successfully for millions of years. Its doesn't take a silicon valley startup like Soylent to fix a problem we never had. [Answer] Nutrition course I took in college mentioned that every culture in the world had stumbled onto some variant of "bean+grain" dish. The two together form a life sustaining base when fruit/vegetables/meat are not available. But let's not fool ourselves: we know from bones of our ancestors just how poor their nutrition often was. We can look at many Third World countries today, or First World medical records of the past century... all of these show that malnutrition historically was a MAJOR problem. Today, we fortify most grains with B vitamins and iron. Why? Because deficiencies in those were EXTREMELY COMMON across the USA until post-WWII. Scurvy was a regular problem until post-1900, when we started to ship citrus fruit reliably to all places with refrigerator trucks. Man may live on bread alone, but it is a poor life, prone to sickness and early death. Our ancestors grew well in places with wide diversity of foods. In modern era, we are constructing all-in-one foods that are actually healthy, but there really isn't a historical analog. So: Yes, pet food for people is possible. You can start by eating dry cat food -- healthier for us than for cats because we can digest the grains often used as filler material. But it isn't really healthy. A healthy variant is a work in progress. [Answer] There's absolutely no reason why a nutritionally-complete, dried foodstuff couldn't be made for people. In fact, search for *'Huel'* which is advertised as exactly that. It's just that there's not a huge demand for it, as fresh food and a variety of it is much more palatable and enjoyable. It may well have some use in disaster-relief or survival situations, where water is plentiful but food is scarce. ]
[Question] [ Your company has just been contracted to develop a purpose built AI. The purpose of this AI is to control a mining station that will be anchored within an asteroid belt. The space station will be equipped with refining and construction facilities, docking bays for transport ships, and rudimentary defense capabilities. The goal of your AI will be to maintain the highest rate of refined metal production to be sent to Earth via transport ships. So any issue which would impede or outright stop a station's ability to mine and refine metal from the surrounding asteroids needs to be corrected by the AI using the equipment on hand. Because of ... reasons ... software updates and physical upgrades will not be available after launch, so every (or at least MOST every) potential issue needs to be prepared for now, before launch. The AI will control every part of this operation including the building of the transport ships and their navigation from the station to LEO (where they'll be emptied by manned crews). What potential issues could impede the space station's production capacity that we will need to prepare the AI to handle? [Answer] Assume average "shortsighted human intelligence". Good enough for solving regular problems, but thinking short-term and locally, so lacking the ability to properly react to long-term issues or see the bigger picture. A lot of smart people lacks those abilities, which hinders their development (and human race). Get one of them as a mining worker, and they will be able to mine properly, but they may fail to prepare for major issues. A few examples of issues that such an intelligence (human or artificial) fails to handle: * Proper maintenance of mining facilities. That's how a lot of mines collapse even with good intentioned efforts to prevent it; simply, the investment on maintenance is focused on the short term instead of long term * Smart competitors subverting or sabotaging the facilities, with tricky techniques (not just brute force) * Strange equipment failures, that require specialized knowledge that only the manufacturer has. Particularly those failures that are not evident but subtle, like giving wrong readings that appear normal * Incorrect estimates of the materials at hand (AI would have assumed the planning engineers were correct), which render the station unable to keep building some critical stuff (like ships), due to lack of a required component [Answer] # If it isn't a general intelligence, it won't work Unless your AI has problem solving skills at least equal to a human, your venture will fail. The list of potential problems is basically infinite. There are *ALWAYS* unexpected problems, any software developer can tell you that. No product is ever bug free. If there isn't some way to solve the problems that the bugs bring up, problems that are unique and unpredictable, your venture will fail. Also, a single human, no matter how skilled, would probably not be enough to solve the problems either. There are too many variables, from software to hardware to astronomy to geology, of things that can go wrong or that will present problems. After all, to mine things on Earth takes billion dollar companies with hundreds or thousands of engineers. So your AI will need to be able to do the work of hundreds of humans. [Answer] **Hostile takeover, by highjackers/pirates and/or a rival AI.** The good news is that you're not alone, brave space AI. The bad news is that it's a dog eat dog, make that an AI-eat-AI solar system out there. As soon as other entities suspect that you've struck Platinum, Uranium or HE3, you'd better be prepared to mount a vigorous defense of your mining claim. The Sheriffs are few and far between out in the Belt. [Answer] > > "We have all the problems of a major theme park and a major zoo and the computers aren't even on their feet yet." - Arnold, Jurassic Park > > > We won't be able to cover all of the issues that your mining station might face in a Stack Exchange post. Space is an unforgiving place with a tremendous number of technical challenges. If I were to somehow condense each issue into one word in this post, I'd still need to type more than this entire answer. We can categorize them though: * Liftoff issues * Landing issues * Mining issues * AI issues * Cost issues To get a sense of just how difficult space is, consider just the launch process. Here's the countdown for the SpaceX Falcon 9, lifted from [another stack exchange answer](https://space.stackexchange.com/questions/1295/what-is-the-purpose-of-having-a-countdown-during-a-rocket-launch): ``` L-13:30:00 Dragon Power Up L-7:30:00 Launch Vehicle Power Up L-3:50:00 Liquid Oxygen Loading L-3:40:00 Rocket Propellant 1 Loading L-1:00:00 Weather Briefing T-0:09:40 Verify that Terminal Countdown has started T-0:09:30 Merlin 1C: Lox Bleeder Valves Open T-0:07:00 Dragon to Internal Power T-0:04:46 Stage 1 & Stage 2 Auto Sequence starts T-0:04:30 Transfer to Internal Power T-0:04:10 Vehicle Release Auto Sequence T-0:03:40 TEA-TEB Ignition System Activation T-0:03:25 Flight Termination System to Internal Power T-0:03:11 Flight Termination System Armed T-0:03:02 LOX Topping Termination T-0:03:00 Second Stage Thrust Vector Actuator Test T-0:02:00 Range Verification T-0:01:30 Final Engine Chilldown, Pre-Valves/Bleeders Open T-0:01:00 Flight Computer to start-up T-0:00:50 First Stage Thrust Vector Actuator Test T-0:00:40 Propellant Tank Pressurization T-0:00:20 All Tanks at Flight Pressure T-0:00:15 Arm Pyrotechnics T-0:00:03 Merlin Engine Ignition T-0:00:00 LIFTOFF ``` Now please note that this is just the timeline for synchronizing tests. Each of these events comes with dozens of detailed checks that took many years to iron out. This doesn't include all of the incredible feats they have to accomplish after liftoff either. Landing is no simpler. There's the amazing show of what it takes to land a booster that SpaceX has demonstrated ([sped up video](https://www.youtube.com/watch?v=4jEz03Z8azc)). There's also the astonishing SkyCrane used to land curiosity ([seriously insane people](https://www.youtube.com/watch?v=p1WX0CATyn8)). Needless to say, the differences in velocities of different pieces is enormous in interplanetary transport, and it takes a lot of care to get them right. Feel free to look up all of our failed landings to see how many things can go wrong. Mining, itself, is tricky. I don't have much experience on the topic, but the general issue with mining is dust. Dust gets into *everything*. At first I'd thought that perhaps this might not be a problem on the moon, with its lack of an atmosphere to carry the dust. Turns out, moon dust is [still nasty](http://now.space/posts/problem-dust-moon-mars/): > > These micron-sized spikes get bombarded by ultraviolet rays from the sun, giving each grain an electrostatic charge. The result: A highly abrasive material that gets on everything and stays there. Hatches, seals, valves, bearings—any machinery that moves on the lunar surface will be subjected to dust damage. "Imagine sprinkling broken glass onto a seal," said Gentry. "And then every time you cycle it, you sprinkle more glass. Sooner or later it’s going to leak." > > > Most mines resolve these issues by having humans there to fix the unexpected. You are only going to have AIs, so you will have all sorts of issues with the AIs. You're going to have to decide how smart they are and how capable they are, and then write your difficulties accordingly. For us, just making robots that walk is still considered an achievement, even if they [may not happy](https://www.youtube.com/watch?v=zkv-_LqTeQA) about it (one of my favorite overdubs). If you make the robots too smart, you have to worry about other issues ([this overdub](https://www.youtube.com/watch?v=sAmyZP-qbTE&t=28s) of the same video shows where that might go). Finally, you have to deal with all of the cost issues. Depending on the value of your mined material, you may have to cut corners. A Falcon 9 launch costs \$62 million, and can carry about 5,000kg (to GTO). That means launching material from Earth costs \$12,400/kg. Obviously returning mined materials from a *much* smaller gravity well will be far cheaper, but you're going to have to pay close attention to the cost of any material you need to send up. [Answer] Almost all major problems your mining base could face can be generalized as a technical failure of one or more technical components of the base. It doesn't matter if a component malfunctions due to an asteroid impact, human sabotage, an alien attack or a manufacturing error. Fact is, the AI must be able to either replace or repair it. This includes all the equipment it needs to make repairs, so these should be redundant. The AI itself is an interesting point of failure here. If the AI *itself* malfunctions, it might not even realize that it is damaged. A possible solution could be to have at least three identical, synchronized AI cores. If one of them ever comes to a different conclusion than the other two, that node is malfunctioning and the other two will switch it off and try to repair and resynchronize it. Make sure that the self-preservation subroutines of your AI make an explicit exceptions for this situation, or your mining base will likely be torn apart by an AI war started by a disagreement about the exact value of the millionths digit of PI. There are other problems, like lack of supplies, lack of mineable resources in the vicinity, the area becoming too hazardous for future mining operations, etc. But these are all problems which are outside of the control of the AI. It can (and should) report them, but it can't solve them. In fact you don't *want* the AI to try to solve these problems on its own, because with its primary priority being "maintain the highest rate of refined metal production", you might not agree with the solutions it comes up with. For example, it might come to the conclusion that the 3rd planet of the solar system still has more resources than these asteroids. The only problem it needs to solve to be able to mine them is the resistance of those pesky carbon-based life forms who are squatting on it. A solution for the murderous-AI-trying-to-destroy-humanity problem can be to make following the [three laws of robotics](https://en.wikipedia.org/wiki/Three_Laws_of_Robotics) its primary priorities. Executing its actual mission would then come on place 4. [Answer] You would have to give it a weapon (I'm pretty sure guns can't work in space, you need oxygen to create fire to ignite the gunpowder, causing a force shoving the bullet out of the casing. There is no oxygen in space, thus no fire can be created. Correct me if I'm wrong) capable of destroying asteroids or armor capable of protecting the quarrying machine from colliding asteroids, as well as the ability to retrieve it when it's done digging, and a way to store the stuff you dig up. ]
[Question] [ Let's just take antimatter off the table right now. As I've learned recently, it's hard to make, expensive as hell and even more volatile, and you can never get more energy out of it than you put into making it, making it the Samsung Note 7 battery of future energy solutions. With that out of the way, what do you think people will be using to fuel their interplanetary ships 200-300 years from now, assuming we're sticking to currently understood methods? I see two big contenders, and I'd like to know which you think is more likely to actually happen. Will they use fusion rockets and hydrogen scoops like the Bussard ramjet? Or will they stick to the much cruder but simpler (and probably more cost effective) method of nuclear pulse propulsion like Project Orion? The way I see it, fusion power frees up more space for cargo and uses fuel that is essentially omnipresent and free throughout the universe, however containment failure in your fusion reactor is an ever present danger and a threat to the safety of the crew. Meanwhile, nuclear pulse propulsion isn't quite as green but can accelerate ships of a large mass (8000000 t) to significant percentages of lightspeed in under 10 days using bombs that, depending on their yield, can be considered relatively small. The technology involved is also simpler and much more foolproof than outfitting a spaceship with its own fusion reactor, and your propulsion system doubles as a weapon, meaning every ship could technically be considered a warship if the situation ever arises where it needs to defend itself. What do you think? [Answer] # Fission power is much more feasible for the near future Fission engines don't get much interest because nuclear materials are banned in space, and because they produce lots of bomb-making products as waste. However, fission engines have several advantages over other options: * Established industrial experience. Not only are there millions of hours of operator experience with power plants, but there is also extensive experience with small portable versions in submarines and ships. The submarine experience is particularly important, since there is 50 years of training on how to build and operate a smaller, safer fission reactor with a minimal crew. * Technologically feasible now. The system I will describe below already has had two prototypes built by NASA as part of the [SAFE series](https://en.wikipedia.org/wiki/Safe_Affordable_Fission_Engine), including a [30 KW](https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20020049426.pdf) end-to-end prototype where a fission-Sterling cycle generator powered an ion drive and a [400kW](http://www.tfd.chalmers.se/%7Evaleri/Ajax/7b_vandy.pdf) fission-Brayton cycle generator. There is no need to imagine theoretical solutions for these systems. * Space makes fission easier. The biggest problem with fission is radiation control, especially in submarines and ships. This problem largely disappears in space. Without heavy lead and water shielding, the weight to power ratio for fission engines can increase significantly, especially with a Brayton cycle electric generator. The 400 kW prototype delivered roughly 1 KW heat for every 1 kg of reactor; and a modern gas turbine [can deliver](https://en.wikipedia.org/wiki/General_Electric_LM2500#Specification) 35 MW with 5250 kg at 39% thermal efficiency. * Materials to support fission reactors are available now. One of the big problems with fusion is the potential for neutron embrittlement from the very high energy neutrons being fired out of fusing D-T reactions. Fission reactors, on the other hand, have currently been in use for decades and the science of neutron damage to metallic structures is well known. * Power density of the fuel is high. While the power density is not as high as, say, fusion, it is still much higher than any chemical reaction. Uranium is a relatively common element. As the SAFE series link above above points out, a coke can of uranium will release the same energy as 50 space shuttle external fuel tanks. Fuel mass will be small compared to reaction mass. * This technology has languished for lack of interest. Space fission engines are actually way behind simply because no one is funding them. The experiments I linked to before ran out of funding in 2004. That is a lot of time in which no development has been made. Putting some funding and research into these engines could probably make them even better than they look now. # Power source - Pebble Bed Fission Reactor. The engine is a [pebble bed reactor](https://en.wikipedia.org/wiki/Pebble-bed_reactor) with low-enriched Uranium formed into [Uranium Nitride](https://en.wikipedia.org/wiki/Uranium_nitride) ceramic pellets. The fuel would be expensive, because the 0.37% $^{15}$N isotope will be preferentially used over the normal $^{14}$N due to $^{15}$N's transparency to neutrons. However, if this became a common system for space power, industrialized processes would decrease the cost of fuel to reasonable levels. Pebble bed reactors are inherently safe because of its fuel is split between U-238 and U-235. U-235 provides higher power density, while U-238 absorbs more fast neutrons at higher temperature in an effect called [doppler broadening](https://en.wikipedia.org/wiki/Doppler_broadening). This means that as temperatures go up, fission rate goes down. The net effect is that the reactor naturally regulates itself at a maximum upper temperature. As heat is removed by the working fluid, fission rate goes up to compensate. In a worst case accident, the reactor will go to max temperature, and stay there, continuing to produce power only a rate fast enough to maintain this temp. # Electrical power convertion - Brayton-cycle engine The [Brayton cycle](https://en.wikipedia.org/wiki/Brayton_cycle) engine is the gas turbine that powers airplanes. However, a spacecraft would use a closed cycle Brayton engine more similar to the gas turbines used on warships. The engine uses a three-stage process of forced compression, heat exchange, and expansion/exhaust through a turbine. The heat exchange would be with the pebble bed reactor, which would be kept at high temperature of about 1000 C. The exhaust section would have two turbines, the gas-generating turbine and the power turbine, as on [marine applications](https://powergen.gepower.com/products/aeroderivative-gas-turbines/lm2500-gas-turbine-family.html). The gas generating turbine takes roughly 30% of extracted energy and uses it to drive the compressor section. The power turbine takes about 70% of energy and drives an electric generator. The working fluid, after passing through the two turbine sets, will then be sucked back around to the compression section. The compression section forces the gasses into the heat exchange areas at very high pressure to repeat the process. The working fluid would have to be an inert gas. Helium and Xenon were both tested in the SAFE series. Argon and Krypton would be other options, as would diatomic nitrogen. None of those gasses would be reactive with metal engine components at nearly any temperatures. An alternate and more advanced solution would be to compress the working fluid directly through the pebble bed. This would significantly increase heat efficiency, but pose problems with some of those gasses as fluids due to their neutron absorption properties. Xenon is a powerful neutron poison, while diatomic nitrogen has undesirable properties as well. On the other hand, helium in particular is very unlikely to absorb a neutron being a 'perfect' 2$p$2$n$ nucleus. # Propulsion - Advanced magnetic engines The last piece of the puzzle is what is actually providing propulsive power. If we are going with a fission-Brayton engine as stated, that only gets us as far as a few MW of electrical output. We still need something to power us. [This table](https://en.wikipedia.org/wiki/Spacecraft_propulsion#Table_of_methods) has lots of options. The key is finding a technology that will have high specific impulse, and thus low fuel usage, and also be capable of thrust significantly higher than the fractional newtons available to currently in-use ion thrusters. Usually, those two requirements can only be met by a large power source, but our fission-Brayton reactor should have that covered. Lastly we need to identify a technology that is farther along than just the drawing board, so that some of the potential engineering problems have been encountered and, if not solved, at least identified. Two technologies that seem most promising from the ability to provide a combination of high specific impulse and high thrust are [magnetoplasmadynamic thrusters](https://en.wikipedia.org/wiki/Magnetoplasmadynamic_thruster) (MPD) and [VASMIR](https://en.wikipedia.org/wiki/Variable_Specific_Impulse_Magnetoplasma_Rocket). Both of these technologies have theoretical specific impulses in the 100+ km/s range, as well as the ability for a single thruster unit to scale up to the 100+ N thrust range. Aligning banks of these thrusters would allow a space ship to generate thrusts in the range of 10$^4$ N that are necessary for effective interplanetary flight with large (1000+ ton) spacecraft. VASMIR works by using radio waves to heat a magnetically confined plasma of Argon propellant. It is currently under development today by [Ad Astra Rocket Company](http://www.adastrarocket.com/aarc/VASIMR) of Houston. MPD works by using the magnetically confined high temperature plasma itself to conduct a large induced electrical current. Plasmas could be noble gasses, or also lithium. An MPD thruster was tested in space on the Japanese [Space Flyer](https://en.wikipedia.org/wiki/Space_Flyer_Unit) in 1995 and research is still ongoing at places such as the Princeton [EPPDL](http://alfven.princeton.edu/). # Conclusion The set of technologies I have described has no theoretical scientific hurdles to overcome. Each of them has a working prototype of some sort. With some applied engineering, demand, and cost reduction through mass production, these technologies could move humanity throughout the solar system on a time scale not unlike the old sailing voyages of Earth, allowing us to truly expand off this planet. [Answer] It depends... Depends on the technology used, how big is the fleet, what are distances of travel (inner solar system, Jupiter, outer gas giants, interstellar), methods of travel as o.m. [noticed](https://worldbuilding.stackexchange.com/a/63866/20315), velocities, desired [ISP](https://en.wikipedia.org/wiki/Specific_impulse)(and thus the efficiency of reactive mass usage) Mars-Earth-Venus-Mercury - Solar-powered crafts make total sense. Jupiter-Saturn-Uranus-Neptune - any kind of fission-fusion makes sense. Interstellar - fusion, Bussard ramjet, beam-powered propulsion if one likes fast travel, but solar-powered, etc also fine if time is not a problem but energy efficiency is(bulk transporting). Mass drivers will be a good option for the whole Solar system, for traveling between planets, space rings, and space lifts are a good option for transporting to/from gravity wells. Thus, until we invent something superior which can easily replace all those methods, and light robust fusion reactors are candidates for that, all those varieties may be used. We struggle not to predict what can or may be used, but to predict the demands for particular needs as a function of time. Amount of energy from fission fuel isn't bad actually - it is about 0.8MeV per nucleon(235U = 200MeV), for fusion it is about 3.8MeV per nucleon the most(2D + 3He = 18.3MeV). 0.01m/sec2 - for solar system it is not bad as an acceleration speed, 864 m/sec per day, or 17 days to gain 15 km/sec. 15km/s is enough to travel across the system, not fast but still. The same speed is not too much for mass drivers too(to launch a craft) and as result, we may expect a combination of approaches as mass drivers can be used to launch a craft, and engines may be used for correction and slow down at the target orbit. But is that combination viable depends on such things as, for example, travel between planets may be significantly faster and cheaper than travel from a planet to an asteroid because mass drivers may be used and for launch and for slow down (this way we also would be able to transfer the energy between bases) As asteroids and small bases may have troubles(and definitely will have troubles) accepting high-velocity ships. Mass driver launching needs infrastructure across the Solar system, reactive propulsion does not need such infrastructure as it relies entirely on itself. However mass driver launch is way more energy efficient, mass efficient for the ship, allow to transfer of energy between bases which may be important for remote bases(let's say at Jupiter) if no fusion is available. And because of those mass drivers, it alone may allow establishing bases on all significant bodies in the solar system, even without fusion. So, what comes first [orbital ring](https://worldbuilding.stackexchange.com/a/63266/20315) or a [good fusion reactor-engine](https://worldbuilding.stackexchange.com/a/59484/20315)? We just do not know, both allow us to solve the problems(travel, energy) in a slightly different fashion, this way it just depends ... on people, on their interests. Fusion will be used for sure, and it is superior, just because there is a lot of fuel for it in the universe, in the solar system, easy to get, easy to use(with technology for doing that). But for a small fleet - 100-1000-10000-100000 ships in the solar system - fission is good enough. To deliver 1 cubic kilometer of liquid hydrogen, from Jupiter, it needs to spend 800 tons of fission fuel and 10% of that hydrogen as reactive mass. And this cubic km of hydrogen may be converted into 567 million tonnes of water (-10% already), and to produce 819 million tonnes of aluminum, or 1732.5 million tonnes of Iron as a byproduct at almost 0 energy expenses - in fact, it can be used to reduce all matter to its elemental form from a 950m diameter space rock(aka asteroid from inner parts of the solar system with average density 3000kg/m3 of typical rock, a solid chunk, which they aren't, mostly) All that is just at expenses of 800 tons of fission fuel, but we mine a bit more than that, 20 times more(at least) than that, and we do not get that many exciting results for our efforts to mine it, I mean energy-wise. I would say spending 800 tons for the result is totally worth the spending. ### Back to OP premise, a side note about antimatter production A note about antimatter and energy of its production, if the technology exists, it can be used the same way as fission can be used - basically, it is the ultimate type of energy accumulation, spaceship rechargeable battery. Even if total efficiency is 0.01% (production, storage, use, conversion to propulsion) it can be used. 1000x1000 km mirror foil at earth orbit may help to produce 4765.44 kg (at 0.01% efficiency of production) of antimatter per year. It is not a big energy production facility(1000x1000km is not a lot in space), and it is pretty a lot of antimatter because 1 kg of antimatter is equivalent to about 1 metric ton of fission fuel (energy of fission fuel [235U](https://en.wikipedia.org/wiki/Uranium-235#Nuclear_weapons) is about 0.00091mc2), this way same 800 metric ton for fission fuel is equivalent to 800kg of antimatter and such station may produce fuel to transfer 6 cubic km of hydrogen per year, which equivalent to refining of a lot of matter, and possibly those materials are enough to build 5-20 new stations. Therefore despite difficulties of antimatter production, it may outweigh the fission and maybe even fusion since you do not need to search and extract those fuels, but instead, you can create antimatter from nothing using the energy of the sun, which at the moment is just dumped into the space void, and which is plenty of available for cheap. The 23rd-24th century - we may or may not use all Sun energy for other purposes, therefore, production of antimatter maybe not be a problem energy-wise, despite the efficiency of the process, and may be capable to cover all our needs in antimatter at the time. But if you choose it, it may be a good idea to place production farther away to increase the efficiency of the production, Gas giant shadows, or near Neptune(or planet X maybe(?)) and beam energy needed for the production from the inner solar system, because at farther distances you can recuperate energy you lose during the production and increase the efficiency of the process. At Neptune orbit, solar irradiation is about 1.5W/m2 it is equivalent to 71 K temperature(black body) and if you lose 99.99% of energy during the production of antimatter, and waste heat is at 1000 K, you can recuperate the 92.9% of waste heat during each cycle and overall efficiency of the process of this imaginary antimatter production facility will be 0.14% instead of 0.01%. And that is worth of travel actually, worth of a "trade" ship. ### Back to OP problem As you may see already, the problem is not what we already know, because indeed our current knowledge probably allows us to look at a bit distant future than we could do 100 years ago, and they were damn good at it (Nikola Tesla, Jules Verne - we are just not enough in the future to fulfill some of their ideas. As I have [discovered](https://worldbuilding.stackexchange.com/a/63266/20315) recently, Nikola Tesla proposed Orbital Ring more than 100 years ago, Jules Verne with his indestructible(at earth depths) fast-moving submarine just a prophet(I know how to build it:) ) and cannon mass driver(also good enough for looking in the future of maglev mass drivers)) But the topic is broad, for different situations for different demands and activities there are their own best solutions. Fission is good enough for star systems. Fusion is ok almost everywhere even with interstellar, but it does not shine with interstellar, except Bussard ramjet, but very good for a star system. Bussard ramjet is relatively good for interstellar travel but inside star systems are not good at all. Antimatter is ok for a star system, and ok for interstellar if the efficiency of production is good enough, but it does not shine with interstellar travel. Beam propulsion is ok for a star system and good for interstellar travel - if combined with some of reactive propulsion or infrastructures in destination point, interstellar variant need a bit more advanced infrastructure (I keep forcing that technology even if no one seems to like it, it is ok to be used at destination point to catch those beam(or mass driver in this case) accelerated crafts, some use case applied to disassemble planets is [here](https://worldbuilding.stackexchange.com/a/45273/20315)) ### Recommendation I would recommend sticking with mass drivers, they are always handy to lift things from gravity wells and to be used upon all massive bodies - in form of tracks, launch loops, orbital rings, not only to launch but also to give a surplus delta-v kick for those crafts, consider it as an advanced version of gravity slingshot maneuver. As the energy production for reactive propulsion to fission, solar-powered(not necessary solar cells), fusion. As for reactive mass to Hydrogen from Jupiter. I would avoid solar sails as not an energy-efficient solution, as for travel in the star system, but an acceptable solution for interstellar travel as it is more mass efficient than other solutions with reactive propulsion, but it is demanding for infrastructure in both cases. I would avoid using Project Orion as a good example for a spaceship because it is a very inefficient design. It is not good at multiple levels. I salute all those people who spend their time on the project, as it is very useful in moving us forward in understanding what is good and what isn't so great, and at that time of the project, it was the great spirit which I would like to see today and applied to our current technologies. Basically, it was great at that time, but its intent wasn't to foresee the future but apply known technologies to the problem of interstellar propulsion at that time. Also, I recommend defining which kind of "trading" will it be in your setting, because everything isn't so easy and you may take look at some space-based economy questions [[economy][space-colonization]](https://worldbuilding.stackexchange.com/questions/tagged/economy+space-colonization) and [[economy][space]](https://worldbuilding.stackexchange.com/questions/tagged/economy+space) [Answer] As Jay mentioned, there is the option that something entirely new will be on the table. But scientists today believe that they have a much more systematic grasp of physics than those 18th century scientists. So: * [Inertial confinement fusion](http://www.projectrho.com/public_html/rocket/enginelist.php#icfusion) for fast ships. * [Mass driver](http://www.projectrho.com/public_html/rocket/enginelist.php#massdriver2) using local fuels. * Solar sails, possibly [laser-boosted](https://en.wikipedia.org/wiki/Beam-powered_propulsion), for slow transports. Check out [Atomic Rockets](http://www.projectrho.com/public_html/rocket/enginelist.php). [Answer] I'm going to bypass the technical aspects entirely ([Atomic Rockets](http://www.projectrho.com/public_html/rocket/enginelist.php) has a huge engine list filled with possible choices), and focus on "why" you'd chose a particular system. The true issue for transport is cost, and in space costs are determined by the amount of energy needed to change orbits and reach your destination (deltaV). Obviously getting to some places will require more deltaV than others, and you can get places faster (even much faster) by using more deltaV, but in general, you want to pay the minimum energy cost, so will tend to choose the lowest deltaV transfer orbits you can get away with. For freight, this could mean decades long journeys by the equivalent of ISO containers boosted into transfer orbits by a mass driver. There is no additional energy cost, no costs for life support or almost any other system cost (maybe a transponder and small engine for fine course corrections as you approach the target). People are not too inclined to be stuck in an ISO container for any length of time if they can help it, much less several decades, so passenger ships will have to go for far more expensive drives which provide high thrust or high ISP and can get you to your destination in a matter of months to years. These are generally quite energetic, and impose lots of secondary costs (engineering, radiation protection, making ships large enough to carry all the required equipment and shielding, then extra fuel for carrying all the stuff....) So in the future, space travel will likely be divided between low cost, low energy freight transport and high energy, high cost passenger transport. [Answer] I think a fusion type generator would work, especially if it wasn't cold fusion. I know a lot of people don't go for that, but here's my thought process: Fusion, by and large, generates a lot of energy, but it has heat as a 'waste' product. But what if it was coupled to a thermoelectric generator? <http://physicsworld.com/cws/article/news/2013/dec/09/new-generator-creates-electricity-directly-from-heat> <https://en.wikipedia.org/wiki/Thermoelectric_generator> So you have your giant boost fusion engine, and the heat is used to power the thermoelectric generator, which, while more ineffecient, could still be used for say, smaller or slower movements, or areas that don't take/need much power. This might also help with the containment problem, because the heat is going somewhere where it's more safely siphoned off. ]
[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/61512/edit). Closed 7 years ago. [Improve this question](/posts/61512/edit) I want to have a setting where legal system allows stocks to be owned only by the individuals. Meaning Joe could own stocks at Acme corporation, but LexCorp can't own stocks in Acme corporation. If LexCorp acquires Acme, either: 1. Acme ceases to exist and all of it's assets and obligations belong to LexCorp 2. Acme & LexCorp consolidate and become a single new company that owns all assets and obligations from both of them. How would corporations look like in my economy? [Answer] The corporations would be far smaller, since most of the financing comes from institutional investors: pension funds, hedge funds, insurance companies, mutual funds etc. The bonds market would be far larger because all that money from institutional investors must go somewhere. You eliminate Japanese keiretsu and Korean chaebol. You also eliminate German type of long term relationship between banks and companies where bank holds shares in friendly corporations and loans them money on lower rates since it has directors on the boards who share information with it. Transparency would be far larger, since you can't hold share in a company that holds shares in a company that owns the yacht that you are using. Tax man would find you in a blink of an eye. Management would have far more power since it's much harder for small investors to organize themselves to protect their interests. Few institutional investors could get much easily enough votes to oust the CEO. [Answer] The original purpose of the corporation was risk management. The original corporation allowed individuals to participate in a risky venture without being personally ruined if the venture went bad. Their liability was limited to however much they put in when they bought their shares (hence "limited liability corporation") Corporations today manage risk by separating different operating divisions into separate companies so that if something goes wrong in one branch, that branch can be liquidated without destroying all the other, perfectly profitable branches. Without the ability to manage risk within a conglomerate, corporations would be a lot more risk-averse. (Of course, this might be a good thing, maybe ...) If you are going to mess with corporations, I suggest you read the following: 1. The Corporation that Changed the World by Nick Robins, a history of the East India Company, a rather unique original prototype of the idea 2. Monsoon by Robert Kaplan, an examination of the re-emergence of the Indian Ocean as the primary theater of global geopolitics in the 21st century 3. The Influence of Sea Power Upon History: 1660-1783 by Alfred Thayer Mahan, a classic examination of how naval power is the most critical link between political, cultural, military and business forces. 4. The Post-American World by Fareed Zakaria, an examination of the structure of the world being created, not by the decline of America, but by the “rise of the rest.” 5. The Lever of Riches by Joel Mokyr, probably the most compelling model and account of how technological change drives the evolution of civilizations, through monotonic, path-dependent accumulation of changes. If this question is not central enough to your project to warrant that much research, you can read a [good overview by Rao at Ribbonfarm](http://www.ribbonfarm.com/2011/06/08/a-brief-history-of-the-corporation-1600-to-2100/). [Answer] By allowing only individuals, not any other entity, to own stock, there are a few obvious implications: * Mutual funds that invest wholly or partially in the stock market become illegal, because those are operated by corporate entities (while managed by individuals, just like an individual would be make a buy or sell order for stock or signing a contract to that effect while representing a company). * Assuming that legislation is not watertight (except for the most trivial of cases it never is, and for those cases, there are always unintended side effects), and assuming that this change is made in an existing economy where such legislation is not enacted, companies would be looking for ways to evade it, for example by paying individuals to hold stock for them and represent the company at stockholder events. It also creates all sorts of hassles when one company buys another. Even taking at face value your comment > > The acquired company will cease to exist and all of it's assets will become part of the buyer. Or they could merge and consolidate into new company. > > > there's still the issue of contracts of all kinds that were entered for the bought company. Even something as simple as building ownership or leases, let alone employment contracts, would need to be managed in light of this. That's hardly impossible, but it does bring with it several truckloads (not just cans) of worms that need to be handled within the legal framework thus established. Generally speaking, you can't change just one small detail and expect other things to remain the same, as everything is interconnected to a lesser or greater degree. Take your example > > Joe could own stocks at Acme corporation, but LexCorp can't own stocks in Acme corporation. > > > Now, Alice works for Acme Corp, and LexCorp seems that Acme Corp is selling really high quality thromblemeisters, and have a great reputation in the market. LexCorp wants to get into the thromblemeisters market but have been unable to make their own at a sufficiently high quality, so they want to buy Acme Corp and simply keep manufacturing thromblemeisters in the same way. Alice has an employment agreement with Acme Corp. When LexCorp buys Acme Corp, if Acme Corp ceases to exist, that employment agreement is suddenly no longer valid, and a new one needs to be entered between Alice and LexCorp. Acme Corp were leasing manufacturing tools, and those agreements are between Acme Corp and some other company; the leases need to somehow be transferred to LexCorp instead. And so on. None of that is impossible, and you could even design laws and legal practices to allow for it to happen "automatically", but at that point, **one has to wonder what the point is of not simply allowing LexCorp to own all of the stock in Acme Corp** and keep all the other legal paperwork untouched because Acme Corp is still Acme Corp, just the ownership has changed. After all, companies can still have multiple divisions that do disparate things which are sold under different brand names, and the profits (and losses) end up in roughly the same place. [Answer] Dividends would be higher, for one thing. Since the corporation has no way of storing wealth, other than putting it in the bank, it presents an unnecessarily high risk, since the bank CAN go under. Far better to give it to the shareholders, who can invest in other ventures on their own. Corporations would thus be much smaller, and less able to manage major changes in their environment, and would fail more often, which in turn would increase the risk of investment, thus leading to increase in interest rates. There would also be a lot more of them, leading to the same effect. Banks would be delighted of course, since they tend to own debt, not equity, so the rules wouldn't bother them. Basically, you'd have an early to mid-19th century economy, lots of risks, many bubbles, fly-by-night operations and banks calling the shots. ]
[Question] [ **Setting:** * modern technology (read early XXIst century), modern humans. * new virgin planet which needs infrastructure. * millions of survivors, but still little by standards of global economy. **Aim:** rebuilding the standard of living so that it is almost comparable to the first world countries of the early XXIst century (the point is not discuss feasibility... tried that and faced too few hard facts and too many of contradicting opinions). The point is how to cut corners, how to achieve almost the same standard, but in many areas to just try desperately to slash cost through mass production, even if it would mean producing "one size fits all" products. I need a flavour that would show that even though some parts of civilization are rebuilt and vibrant, when one looks carefully there are clear signs, that this is not XXIst century earth, this is a planet built after the apocalypse and a high price had to be paid to make it work. So ideas: 1. Cluster computers instead of supercomputers - there is a need for personal computers, but not enough market for big ones - thus only small ones are produced and just in case bundled together. 2. Desperate use of the same type of containers - all pills are being put in the same kind of box (just different labels), there are a few standardized jars and all kind of food products from different producers go in the standard box. 3. Using narrow rail gauge - its cheaper and less population means that there would be no demand for anything bigger. 4. If there is already produced piston engine for cars, just use the same engine (maybe with turbo charger) for aircrafts. For practical purposes it means slower aircrafts. 5. Battery cells with surprisingly similar shape to rifle ammo. Yes, the same production line was used... 6. Incubator made out of car parts (actually this was created in [real life](http://blogs.scientificamerican.com/news-blog/babys-hot-wheels-an-incubator-made-2008-12-16/)) 7. A few types of vehicle chassis, engine (or the same type, of engine just scaled up) used for absolutely different types of cars. Any other ideas? EDIT: I assume that general knowledge about technology is preserved (still lives a generation which remembered the past world, there are still abundant working examples of prior technology, just here and there there is no knowledge about detailed technological process and problems to use economics of scale. [Answer] The "Cheap Planet Project" Objectives: * Use standard solutions if possible * Remove costs with marginal loss of quality * Make reusable products * Durable solutions, environment friendly if possible Assumptions: * If we need any mineral, it can be mined with availability similar to that of Earth * There is enough time to set up traditional production lines * No knowledge lost * Any known machine can be built - or we just pretend we took it from Earth * Land needs to be distributed to the population * Economy is a continuation of that of Earth, the concepts of money and value remains. A new currency is created. --- List of proposals: 1. The urbanization efforts shouldn’t provide standard full houses, don’t provide high density housing either. Both are expensive and there is limited demand for highly packed housing. Instead give ["half houses"](http://www.archdaily.com/447381/villa-verde-housing-elemental/). That is, houses with the bare minimum components, but with a solid frame to expand. Ideas for building materials: * Adobe * Cargo intermodal containers * Back to stone and concreteAddendum: use ceramic pipes. 2. Create an organized grid for buildings, with standard signaling. And make those signs machine-readable (RF?). There is no GPS - there are no satellites -, so automatic navigation will have to come from local networking (vehicle to vehicle connections) and sign reading. Make all vehicles self-driving, driving is banned from the get-go. 3. Interlace building blocks with green areas (parks) and alternative car ways with pedestrian/bicycle ways. So each other block is a park, and each other street is a pedestrian way. Note: park maintenance should serve a employment source. 4. Architecture for non-residential buildings must be efficient first, practical second, beautiful last. Go away from the idea of large glass panels in the outside. Favor natural ventilation, large hallways, and internal open - maybe green - areas. Use tick external walls to resist the weather and absorb temperature changes. 5. Incentivize people to use the green space of their houses to plant fruit trees or some other form of produce. Assist people to build green houses or hydroponics if needed. Also enact mandatory composting - which they can use for fertilizer or sell. This gives people a virtually free source of food (their backyard) and income (if they have surplus). This is needed since there is no large food infrastructure, let alone nonperishable food. 6. Do not mass produce things that people may build by demand. Instead provide workshop spaces, training and free blueprints for furniture, common tools, etc... this means that time, material and space won't be wasted on stock that nobody buys - people would still pay for the materials. Blueprints should be created to minimize materials, and have comprehensive build instructions. For inspiration: [the 50-cents microscope](http://www.ted.com/talks/manu_prakash_a_50_cent_microscope_that_folds_like_origami). 7. Promote neighbor markets. Provide the space and infrastructure for a local market run by the local people (no big brands). These should serve as a platform to exchange, buy or sell home-made products. 8. Use nuclear power for energy supply. There are already technologies in development handle what we currently consider nuclear waste. Aside from such waste, nuclear power is safe and clean. 9. You may add reliability to the electricity network by using communal [molten salt batteries](http://www.ted.com/talks/donald_sadoway_the_missing_link_to_renewable_energy) - done well, it should allow for a wider use of green energy sources that don't produce constant energy output (solar, wind, etc...). Even if you use nuclear power - which I think you should - the batteries add resilience to the infrastructure. 10. Enact mandatory trash classification. That would go hand-in-hand with mandatory composting. And have the government provide recycling infrastructure. 11. Create a regulated forestry industry, one that ensures the health of the soil and that the amount of chopped trees is lesser than the amount of trees grown. It would take years to be commercially viable, but it will be worthwhile. 12. Add new regulation for industry creation that requires the company to demonstrate that their products are recyclable. Any product that goes to market must include instructions for trash classification. 13. Cooking can be done with electricity. Sure the electric network may not be reliable, but there may not be fossil fuel available in this new virgin planet. 14. Yes, lots of cheap small computers instead of big powerful ones. Drop precision in hardware sensors - which can be corrected by noise filters in software - to get cheaper hardware. Also lose precision in hardware output (low-res audio and video) for economy. 15. Similarly, long distance networking can be done cheaper if more transmission erros are allowed, which then translates to slower accurate transmission by using error correction in software. 16. Make all computing modular, including portable and mobile builds. If a part breaks it should be easily replaceable instead of replacing the whole device. 17. Electric cars. Because again, are there fossil fuels? And also because Need For Speed was not released on the new virgin planet. I mean, efficiency of the engine is more important than speed. 18. Air transport: drones for package delivery in city, electric planes for personal travel, dirigibles for mass transport. Otherwise, go by land, land is cheaper. 19. Assume void all prior copyrights and intellectual property. All commercial and industrial knowledge is public domain. **Addendum**: 20. If not metal, glass and ceramics can do great for durable dishes and utensils. That would not require fosil fuels (plastic), large crops (bioplastic), and will not be possible host of bacteria (wood). Bioplastic are great, but the virgin planet does not have the infrastructure for it. You may also be interested in [fungi based packing materials](https://www.ted.com/talks/eben_bayer_are_mushrooms_the_new_plastic). 21. [Wood based integrated circuit encapsulates](https://www.youtube.com/watch?v=Bma2UKsbTDw). Note: also avoid wired networks. Go full wireless, less materials. 22. There is a problem of fibres. We need to build mattresses hammocks (less materials) to sleep. We need clothes. And birth control is important (condoms). I have a solution: [Spider Silk](https://vimeo.com/26052660). *I guess we can save some material on clothing, too. With hammocks and revealed skin, my picture of this world has changed. Pulp sci-fi with bikini girls might have been onto something after all.* [Answer] An important factor would be to allow for the biggest constant: Change. You want to create things in a way that allows disassembling them, and modifying them. This should be true for buildings, roads and all kinds of installation infrastructure, but also for all kinds of machinery. For buildings that means that all buildings should be set up on a standardized grid and made from standardized components. While this may sound dull, this is not necessarily the case: the only thing that has to be standardized are the connection points. So, a wall has defined dimensions and defined connection points, but everything in between those boundaries is free to be designed any which way. Obviously that allows for cheap production of elements, and for simple and cost efficient building as well as modifying. The same platform concept should be applied to vehicles, and where possible to electrical and electronic equipment. A lot of the diversity we have in modern day life is not necessary: just assume there were two kinds of smartphone on the market: a strong one and a cheap one. Apart from the desire tho have something special (be the envy of your neighbours and whatnot), the loss would be negligible. The only people really suffering would be big companies. And those are not present. And then, of course, you may want some drastic changes in your economy: decentralize and use additive manufacturing, use renewable materials and energy sources. Since you are starting from scratch, no existing infrastructure needs to be modified, noones personal interest is harmed when you build something new, so you can just do it. Again: plan for change, this will make updates and correction of ideas that are not so great in hindsight much easier. [Answer] I will assume that there exists a centralized semi-autocratic government which can enforce all these ideas, at the cost few civil liberties, and has sufficient basic resources. The best possible situation is when you see humans as resources to optimize and invest in. **Cities and Buildings** City designs and building designs would be completely different, most building would consist of both residential, retail, entertainment, school/university and work. Most people will work, reside and be capable of living in the same building drastically reducing travel time. All buildings would conserve space, resources and be utilitarian, rather than a status symbol. Even things inside the houses would be utilitarian all costly decorative things would be discouraged. Some devices or objects would communal for maximum efficiency and usage. **Travel** Cars/Vehicles would be fully automated, the reason it is hard to make a self driving car is that AI has to compensate for human errors. By enforcing mandatory automated vehicles, you can bypass the problem increasing efficiency and speed. Air Travel would be very limited, a rare luxury, same for Cruises, and any form of recreational vacations. Most transport vehicles/ships used for inter-city trade would be limited to essential raw materials. Any objects which adds to transport would a luxury, this includes but not limited to artisan products, crops/plants/animals which do not get cultivated locally, ornamental objects. **Energy** We currently have technology to make 100% safe nuclear reactors with no radiation leakage, which automatically shuts down to avert possible catastrophe, without the stigma associated most of energy will come from nuclear with some renewable. Centralized energy efficiency would lead to automated factories shutting down at evening to accommodate the increase in usage due to people returning homes. Energy intensive systems would work nights and afternoons. Unused public lights, house lights would automatically and if necessary remotely shut down. Refrigerators, ACs, heater would be forced to run at limited near optimal range of temperatures. **Computer** Computers will always be connected to decentralized system which will be used to spy, delegate excess computational capabilities, information from people will be used help them psychological and used to assign optimal jobs. Blockchain and other better technology will be used to optimize all possible resources. Centralized education to enforce ideas and culture of conservation. **Others** Standardized components, limited choice, mass producible objects, a system similar to decentralized communism. Having a hobby would become a luxury. Outdoor entertainment would be replaced by online games. Guns, weapons and military would be limited to bare essentials. Religion would be non existent, or be forced to spread the values of optimization and cooperativeness. Spying would allow easy detection crime and fraud. Even forcing only genetically better hand picked in-vitro babies. Democracy and free media would be banned/restricted as it starts propaganda warfare, all jobs/positions would be merit based. There would be a lot cultural changes forced upon people. [Answer] Automatic opening doors... but it is actually a person watching on a camera hitting the button. There could be a lot of automation faked by hiring people. Low res graphics to save power, easier to make screens. Cash economy again because credit card bookkeeping is maybe actually hard to get going (so I've heard, but can't say for sure). Electric grid is unreliable so gas lamps are discretely placed everywhere, just in case. [Answer] Huge amounts of automation that its somewhat hidden, there may be lots of buildings, cars and factories but none have humans working in them, buildings are 3D printed, cars are self driving and in factories robots do everything. This happened as in the beginning there wasn't enough people to do those jobs, people itself have mostly one of either two occupations, owners of those robots and automation AI or live on "basic income", which its an income given by the government as now they can't give enough employment to everyone. Also people have a huge paranoia of ruining the world so there are very strict rules about what can and cannot be done to the ambient. Due to that a lot of personal liberties have been cut down, not everyone can own a car, communal housing has become commonplace, even the number of childs that a couple can have its severely enforced with huge penalties if you have more or less than what the government says you have to have. Poverty became a weird status, its not reflected in material things but in the amount of liberty you can get. Energy have gone to a mix of renewable energies and nuclear fusion (hey its always 20 years ahead due to funding but I bet that if the world were to collapse funding and oil companies getting in the way wouldn't be that much of an issue). People surveillance become an orwellian fan dream, its way more advanced and deep than where currently is, profiling your browsing habits, social networks, gps and other factors the government can predict with a big certainty what you like, what you want, what you think and if you would commit a crime, they also give you a score, that score its a determining factor to get education and jobs, the higher, the most access you'll get. If your score falls there are three levels: 1.- At the beginning you will be sent to an AI psychologist to treat you, but medication its still optional. 2.- You will be forced to be medicated. 3.- You will be detained and sent to a reeducation camp [Answer] * No coins, just credits. All people use chips which can store only a limited amount of credits, but can be recharged in the bank. The bank receives credits generated by the evaluation of work of individuals, to distribute back to the individuals. All products have universal price dependant on the evaluation of work that the individuals invested. This makes prices stable and prevents inflation. The credits used to purchase products get to the company that made them. if individuals make products independently they receive credits for selling the products, not for making them. This system is not hard to keep operational. (This system could also start some side currency that people will exchange for services, so the bank should have some "help tokens" that people can give to other people for services and get a credit reward) * Make electronics visuals simple, unless the point of the electronics is to display something in detail. Making simple displays on devices like mobiles reduces the cost and the technological requirements. * Don't jump for hydroponics, use the land that you know will turn to building parcels for agriculture, it can reveal many issues with the place before you start building on it. * Don't mess with swamps and shallow river beds, they are a source of fertile soil and will come in handy when the population expands. They are also hard to dry and stabilize, so don't try. * Use trains for most transportation, they are easier to run and maintain. Use cars only for short distances. Make most cars non private, make them company property, discourages people from doing dumb things and encourages them to work, so they have access to them. * make electromobiles for civilians and try to stay away from fossil fuels as much as possible. * Make fossil fuels accessible as soon as possible, todays society depends on them, your will too, there is no way around that. * Make bio-fuels * Plan cities ahead of time, make the cities so they can be modularly expanded. Surround the industrial areas with living areas and place the industrial areas on the end of the city. red and lime Place the offices between the living areas. light blue Place the commerce and entertainment in the centre dark green and violet Make all the zones dotted with police stations and fire stations hospitals and other administration buildings. dark blue place the control, labs, colleges and town hall in the centre. orange the edges of industrial zones will have (brown) train stations and infrstructure that unloads resources and either stores them in the (pink) storage areas or delivers them to the industrial areas directly. the inside (pink) areas can be used for anything really, but having a secondary storage for the sommerce and entertainment zone, along with some more living areas would be the best option. the black lines are the highways and city traintracks. And don't forget that living areas should have shops with everyday things and small police stations and clinics. [![city plan](https://i.stack.imgur.com/gdFCA.png)](https://i.stack.imgur.com/gdFCA.png) EDIT: I forgot to add power plant zones, these could be placed in the middle of the industrial zones closest to a dark blue zones, so fire stations are near. Or in case of nuclear power plants in a location away from the city with a smaller settlement to take care of everyday operations or a city with just a few triangles forming it. Colonists should try to get nuclear power plants ASAP. They're the best source of energy we now have and can provide power to several cities at once. You can also use them to power large naval vessels. Provided that all safety procedures are followed and no wars can break out (so no extreme tests with drunk engineer in the lead, like in Chernobyl, can happen) nuclear power is one of the best sources we have. Most natural sources are not reliable and have many problems. So do not depend on them. Wind turbines are loud and scare animals and their power production depends on the weather. Solar panels work only certain hours or not at all if the weather doesn't like you. And on large scale can prevent the area from staying moist, because the surrounding vegetation must be removed for maximum effectiveness. Only reliable source is a water dam power plant, but dams can harm the ecosystem of waterlife and make it problematic for boats, but also prevent floods and would provide water to cool the nuclear plants. But are useless during droughts. But are unlike other sources can produce alternating current directly and it's power output can be regulated. There is also new experimental sea wave power generator which should in theory be stable, you could look into that. So unless you want to build large batteries for each city which would be terribly expensive (mind you we are talking in human labour not money based on a whim of speculants on a exchange market), don't use solars and wind power on large scale. Each building could have solar panels on roofs and batteries to preserve the generated power, but that would be either a later stage or used in places where the powerlines are yet to be built. Producing more energy for the rest to use would of course be rewarded. ]
[Question] [ On the planet of the Aves, birds have evolved to dominate the Earth instead of mammals. Of the thousands of species in this world, both on the [ground](https://worldbuilding.stackexchange.com/questions/51622/planet-of-the-aves-quadrabirds) and in the [water](https://worldbuilding.stackexchange.com/questions/51661/planet-of-the-aves-aquabirds), the only one to develop sapience are a species of crow-like flying birds. As I design this species, I have wondered what kinds of weaponry a crow would be able to use. With a species physically similar to crows, what weapons would they develop for use during the stone-age phase of their existence? These would be used both for hunting and for skirmishing with other tribes so fights involving more than 20 or 30 would be highly unusual. The Un-human physiology of crows provides a number of constraints in the ways weapons can be used and designed, but does it also allow other new options? A list of all Planet of the Aves questions can be found [here](http://meta.worldbuilding.stackexchange.com/questions/3939/planet-of-the-aves-series/3940#3940) --- Keep two things in mind here, 1. They need to be able to both build and use these weapons. 2. They are for all intents and purposes related to this question, crows. [Answer] Crows (and other corvids) do a lot of their fighting in the air, so I'll assume your Stone Age Crows do too. Here's a David Attenborough video of [fieldfares defending their nests from a raven.](http://www.bbc.co.uk/programmes/p00c6ht4) Towards the end of the clip, they do aerial poo bombardment, to splatter the raven's feathers with bird shit. Apart from being gross, the feathers will get gunged up which will affect their function. Short term, it will mess with your aerodynamics a bit. Long term, Sir David says it can cause the feathers to get waterlogged, which can be fatal (mucks with the bird's ability to stay warm, makes it heavier so less energy efficient to get airborne). So your smart crows will make 'artificial poo' to bombard their enemies with. Anything sticky which will mess with the feathers and be difficult to clean off will do. Perhaps a blob of plant latex (sap) or pine resin on a leaf (held carefully so the carrier doesn't get gummed up). If there are tar pits in their territory they are on to a winner. If they invent fire, they can start boiling up animal hooves and the like to make glue. A crow battle will be like a bunch of kids having a water bomb fight. Once they invent catapults, slingshots or 'cannons' it'll be like a paintball fight. As well as glue-bombs, they can target the [flight feathers](https://en.wikipedia.org/wiki/Flight_feather) with edged weapons - say a sharp flake of stone or shark tooth held in a talon. If you can slice or sever enough flight feathers, the wing ceases to function and the bird not so much flies as plummets - you have grounded your opponent. Effectively you have clipped its wings. Clipped feathers don't grow back. The victim will have to either: 1. Pull out its own clipped feathers to stimulate new ones to grow. Ouch, painful! And the indignity of being flightless like a chick again! 2. Wait until the clipped feather moults naturally. This could take up to a year. Making sharp flakes of stone: If you don't want the crows to be dexterous enough to do flint knapping, then they can do the less subtle technique of grabbing a suitable stone and dropping it from height to smash on the ground. The shards will be rather random in shape and size, but usable. Crows and gulls smash open molluscs this way. In fact, sharp shards of mollusc shell would be just as useful as fragments of stone. [Answer] See also [this answer](https://worldbuilding.stackexchange.com/questions/42120/what-aspects-of-a-creatures-hand-would-make-it-good-for-climbing-but-not-good-f/42147#42147) of mine where I make the case *It’s not the hand, but the brain*. If the brain has the circuitry to expand the body image on the fly, then *any* way of grasping or crudly controlling another object will be used to some effect. The evolution of grasping limbs and better dexterity in wielding will *follow*. The New Calidonian crow has physical adaptations for tool use: the beak is straight so it can pick up something and hold it forward in front; the eyes can focus on the point just past the beak so the crow can easily see what he's doing. But before all that comes the mental wiring to be able to use an extension of his own body in such a manner. My own pet, a Bronze Winged Pionus, surprised me a couple weeks ago when I saw him employing tool use for the first time. He has a hooked beak which would not be at all good in the manner of the crow’s. But he also has [zygodactyl](https://en.wikipedia.org/wiki/Bird_anatomy#Feet) lower limbs which make excellent hands, and a range of motion that's impressive, although he has to perch on one leg to use the other as an arm. When losing a feather, it appears instinctive that he chew it before discarding it. Some recycling I suppose. In this case, after chewing it quite thoroughly I saw him manipulating the remaining quill: holding it with the *tips* of the talons, the [middle part of the foot/hand](https://en.wikipedia.org/wiki/Tarsometatarsus) becomes another useful joint. He could move it to either side of his body with some surprising reach, and rotate the quill more than 180° to point in either direction regardless of which side of his body he was holding it near. Then he proceeded to use the tip of the quill to scratch himself. Now if he was scratching himself whith his claws in the usual way, but trying not to let go of his quill at the same time, the quill would be sideways flat against his body. Instead he *carefully* worked the tip against the side of his head, which means holding his foot/hand at a right angle to the use of the claw; and moving it around to control the *tip* which is now another joint away from his actual limb. Being able to do that at all requires the **brain** have the tool-feel ability. So birds have multiple ways of grasping and controling other objects. Any slight ability in that regard will be improved by natural selection once the **brain** has the ability to use tools. As for what they would do with their stone age, I think that’s defined by the natural resources. Smart tool users will *find a way* to hold something to further the need of manipulating natural resources. The stone age is so named because stones survive to be found; but it was also the wood age and the leather age and the leaf age etc. The things in the natural world that are available and what physical properties they have for exploting by fairly direct modification of the original items is what will define the stone age. The species’ unique phisiology will affect the *handle* end of things, not the business end. They’ll make what tools *can be made*, regardless of what their grasping anatomy is like. [Answer] a net. Sound strange enough, since you can't kill anyone with a net. But for an avian race, getting tangled up and fall from the sky would be pretty much lethal. However, it's not the main point. Because it's stone-age, your crow won't fight in open battle, but **raiding** -just like the native American warfare. And that's where a net come in handy. 1. the weapon Net is not a damage-dealer like normal weapon; instead, it's a support weapon that immobilize the enemy and give you significant advantage. On an airborne target, it will cause the enemy to fall to their death, or at least take a lot of time to get out -enough time for you to damage him with talon and beak. On a ground target (which is most likely for a raiding scenario), it will keep him on the ground, vulnerable from any attack from above. 2. the making net-weaving for bird seem impossible, but teamwork is the key. (Think of the bird's beak like your thumb and index finger.) the material: net is made from rope, and rope is made from fiber. 2 bird can tear fiber from palm leave (like how you tear apart a piece of paper). 3 bird can make a rope from 2 fiber (more fiber, more bird). 1 will keep the rope's end in his beak, while the other 2 will hold a fiber each. These 2 will criss cross each other (like how you twist the fiber to make rope). and finally, 2 bird can knot these ropes into a net. 3. the tactic the net should be heavy enough to immobilize the enemy, so it's better to have 2 bird carry 1 net (moreover, the net is also spread out, make it easier to caught something inside). After casting net, the pair will attack the trapped enemy with their talon and beak; you can even have some bird carry a rock to make short work of it. After take out a good number with this method, the band with mob up any survivor with their superior number. [Answer] It doesn't. Weapons are tools; tools that require lots of other tools to make them. Whether a crow can use a sword or a gun is immaterial: a crow that doesn't have any manipulating appendage better than claws can't build a forge or a grindstone or a drill press. The only options I see are: * find rocks and drop them on your enemies * pick up ground-bound enemies and drop them on the ground * find a naturally-occurring poison and somehow get it on your enemies without contaminating yourself * claw and beak ]
[Question] [ Following the general trope with Silver/Golden Age Superheroes' relationship with society, law enforcement, and government we can get the following: * Superheroes may or may not work directly with law enforcement (officers, detectives, DAs, etc) * Superheroes, for the most part, aren't part of government and do not answer to the government * Superheroes apparently, to some degree, can enforce the law and this seems to be societally acceptable (even often directly praised by the press) I'm going to extend this trope a bit further and limit it: * Superheroes' secret identities *may or may not be known to law enforcement* (answers should account for both possibilities). As a further constraint for this question and to produce quality answers, the setting should be considered semi-grounded, and thus be far, far more so realistic that is typically seen in DC or Marvel comics. Answers should take into account a realistic society filled with realistic people. Likewise, historically, superheroes have been people with all the flaws that comes with being a person. Society would have developed around this. This isn't science-based (some liberties can be taken), but answers shouldn't handwave any problems with magic or pseudo-science. How can these traits be explained collectively? [Answer] Golden Age superheroes were vigilantes. This makes them criminals. While they may have muscled out malefactors their activities were illegal. The Comics Code cleared up their collective act. That's comic book history. If we lived in a world where people with super-powers were commonplace, the main question is how would they use their super-powers, and secondly how that those uses affect law enforcement. To consider this, let's assume there are a wide range of super-powers and this can go well beyond the super-powers normally depicted in superhero comics, movies, TV shows, and fiction. Firstly, there will be many supers whose super-powers are unsuited to either law enforcement or criminal activity. For example, super salespersons, super-models. super-politicians, super-athletes, super-firefighters, super-doctors and super-nurses, super-actors, and super-scientists. Most of these supers can make money and enjoy more comfortable and successful lives using their super-powers to further their careers. Secondly, there will be supers whose super-powers are better suited to law enforcement. For example, super-strength, invulnerability, x-ray vision, super-hearing, and super-stamina. Supers like these could also work as body guards, secret service agents, night club bouncers, security, and in the military. These super-powers can also be used for criminal activity. Thirdly, there will be super-powers that very naturally lend themselves to use for criminal purposes. There are often other possible career paths for this type of power - for instance, gainful employment in the more sinister type of government agencies that do things nobody wants to own up to - but they are easily (and sometimes most naturally) used for criminal purposes. For example, death-touch, emitting lethal doses of radiation, teleportation (ideal for theft and burglary in addition to its [less nefarious uses](https://worldbuilding.stackexchange.com/questions/142436/personal-teleportation-as-a-weapon/142509#142509)), total mind-wipes that leave victims mindless vegetables, and hurling energy-bolts in the kiloton and above range (whose only real use otherwise would be military, where the whole idea is that *because* you have it, you never have to use it). Supers who possess the third class of super-powers may not wish to embark on a life of crime, not automatically, but it would be so easy to stray. In a world with many supers and wide varieties of super-powers not all of which will be used for crime or law enforcement supers will have become commonplace. For reasons of public safety, supers will be registered. Their names and identities will be recorded and maintained on secret registers. Some supers may operate openly and be on publicly accessible registers especially if they used their super-powers commercially. *Zippy Couriers Uses Only the Best and Fastest Super-speedsters for Parcel Delivery! Go Zippy!* Supers employed in law enforcement will have the usual benefits of gainful employment. Steady income, expenses to replace damaged uniforms, pension plans, legal recognition, and retirement benefits. Plus the opportunity to work with other supers and enjoy collegiality. Police and law enforcement supers will have to deal with criminal supers. Super-powered criminals will do what criminals have always done. Gain wealth through violence, the sale and distribution of illegal goods, services, and substances, and the ability to coerce ordinary citizens to their will and contrary to the law of the land. In many ways a world with supers working on both sides of the law will be similar to our world without supers, unless there is a large number of supers with super-powers capable of making major causes to the social and political order (like blasting cities off the map with a single glance), but there will be a major difference between those with super-powers and those without. But that moves into the area of social and cultural differences and is outside matters of super-powered crime and law enforcement. [Answer] **Both the heroes and villians are mob bosses.** **Heroes:** * Keep control in their territory, makes sure order is kept and the people are more or less free so long as they obey the hero's sense of justice. * Have various underlings, either lesser heroes ("sidekicks") or other loyal agents. Some of their agents may be policemen who are loyal to the hero. * Respect other heroes for the most part as respectable * Some work with the law enforcement to keep order. others work outside of it, clashing with the police from time to time. This also affects how well the identity of the hero is known. The hero only reveals to the police what he feels they need to know. * Some are less respected by the police and occupy a grey area between hero and villian. They still uphold order, but they are disliked by the police and/or people. * Hero's "protection money", given by the local citizens, keeps them protecting the area from villians. This is a difference between romanticized superheroes, who either happen to be millionaires or magically support themselves financially and save the world at the same time. **Villians:** * Have a bunch of loyal cronies who flock to them because they are rich, powerful, and influential. The more powerful the villian, the more minions they have generally. * More frequently clash with other gangs, including other villians. Also clash with the police who attempt to crack down on their crimes. * Have little respect for law and order, use their powers selfishly. * May have a secret identity, simply known as the leader of a certain gang. Or he may be well known but still uncatchable. * Also collect "protection money", but through extortion. The difference between this setup and the romanticized hero/villian interaction mainly lies with the hero. The villian still behaves generally the same, robbing people blind and abusing their powers. The hero, rather than being motivated by altruism is also financially interested in the citizens. The hero though, mainly lets the people go about their business and does not extort them as much as villians. This "lesser evil" in turn makes people willing to hire heroes rather than be forced to pay the villian's excorbiant fees (and then still be robbed). Businesses that refuse to pay for a hero are not protected and soon hit by the villians' gangs. In this way, the hero is not actively looking to grow his territory, but is willing to protect anyone who pays his gang for their services. [Answer] There is a problem with your question which is at the heart of many misunderstandings about law in the US. Citizens can do everything and more that the police can do, because the government is beholden and made up of the Citizens. If you watch a police officer and they do x, you can do x too. The difference is that they have licenses and government issued warrants and such that allow them to do a few more things legally than you. It's not because you couldn't go through the same processes and get those approvals, but because part of those checks are an insurance to everyone that procedures have been carried out to make sure these things are on the up and up and they are held accountable. Let's take Superman or Spiderman. They are not breaking any laws when there is a bank robbery and they intervene. They are well within their legal rights to do that and being that the cops would see how useful and helpful this is they'd work with them. They are government agents, because that's how the US is, but you mean they are not official representatives. I don't see that as an issue. There is no reason that they have to be official reps and this goes into the 3rd point... Everyone can arrest someone else, etc. You, as a member of the US citizenry have the ability to arrest people, ie. detain people when they have commited a crime. Just like the police. The difference is in how much leeway we give the police on this matter, because it is illegal to detain someone forcibly. Both you and the police can be sued and criminally charged if it is shown not to be justified, but the police can get away with it longer, simply because they have a more reasonable argument that it is justified, given it's their job. What IS vigilantism is more akin what Batman does (though you can debate it, but we're just going for simplicity sake). Batman looks for clues, enters into peoples' property, and actively starts situations with people who are possibly criminals. I don't know how far Detectives can push to enter property and such because I haven't looked into it, but let's say you can get a license to do that. The primary difference between what you as a citizen can do and what the cops can do is start a situation. The police can go to a wherehouse that has criminals in it, bust in and arrest everyone. You cannot. However, if police bust in a place and start arresting people you can help. Likewise if you hear or see something going on you can interfere. The primary reason that "Heroes" are not welcome in the real world is that they don't have infrastructure, cause more problems than help due to this, and are generally less easily held accountable through the insurrances we have created. If real Superheroes started appearing you have to extend some of the assumptions of a police officer doing their job to the Superhero, such as detaining people for longer. The main issues are really augmentations that you might have to make to certain things, such as can Superman ever really be a Vigilante? Remember, what makes a vigilante is initiating the situation without seeing or hearing a justifiable reason to interfere. Superman can hear everything. Superman can naturally see through walls. Is it illegal for Superman to bust into a warehouse where victims are being held? What if there is a gun pointed at them? A cop wouldn't know. A normal person wouldn't know so to them the answer is that they can be vigilantes, but if they did it it would be illegal, but if Superman did it it wouldn't under our laws, because he saw it. What about people like Cyborg? They don't just have internet access, they have a direct access to the signals that are floating in the air and he naturally decrypts them without any special thing going on. You need warrants and such to do this type of stuff, because you wouldn't "normally" be able to see/access that stuff and it is presumed "private", but Cyborg does it without thinking. Is it then not illegal for him to have such access? What about someone that could time travel, but not interfere except in the present or could read minds? Where does their justifiable interference stop? Where does them "seeing" things stop. If I can see you're entire history from the moment your born till present and know the crimes you have commited and all those type things, as our laws are I would be 100% justified interfering at any point in your life that I so desire because you're the one initiating the action from my perspective and I have reasonable cause to stop and arrest you. On the other side of the spectrum you have to establish whole new rules of the concept of escalation of force models. Superman as a hero is under no danger from the average citizen, but just about any action he takes is clear a level of force that would probably lie outside easily definable boudries of force. On the other hand, an evil superman, when is deadly force reasonable? Superman can kill you with a punch from the other side of the Earth before you can unholster your gun and discharge 1 round, and it wouldn't even be lethal to him. Does that mean then that any interaction with Superman that there nothing that you can do (with normal weapons/actions) that would ever be considered illegal? Those type of boundries would probably be established along with the extension of presumptive abilities of police onto Supers. But other than these modifications to current law every point you made is perfectly within the legal bounds of civilians today. It's just discouraged due to various accountability and safety issues. Also, as far as the idea of Superheroes in general not working with police/military. I find that harder to believe in most cases if we're talking abilities in line with x-men and lower tier heroes, because working with the police as part of the police would just be, overall, better due to infrastructure, support, public scrutiny, economics, etc. Superman doesn't need that and working "with" the police would slow him down. Batman has that through an elite selection and training program + money. Nightcrawler, Rogue, Jubilee, Mystique, Cyclops, Spiderman, Captain America, Iron Man, etc do not. The issue there is then 16 year old Peter Parker, bit by radioactive spider and gets all these powers that can be very useful, but he's 16, so he can't join the Police/Military, but he certainly won't be sitting around doing nothing with his powers, so what do you do with him? After a while what you really will end up getting is that you'll get training facilities and powers as being a natural part of your medical records, and perhaps licenses for using powers of various types in public and you might get a society that is quite a bit different in certain aspects, for example, clothing. People might go the route of "you can't use your see through anything vision under any circumstance unless you're doing x" or they might realize they can't control that and to try to would be anti-freedom and as a result wear less clothes, because what's the point if random people can see through it anyways. Hope that all helps to answer your question. It's not really a special development that would happen to make a society act in the way that you're talking about, because our society already acts in that way. Its just not apparent cuz we don't have Supers running around (for the most part... I mean have Zombie-esque type people in Florida and that's pretty Super) [Answer] 1. **Superheroes may or may not work directly with law enforcement.** This can be explained by saying that superheroes must be classified, categorized and organized. While this may cause tensions, it is what would be required for governments to let them work on their own. Another solution is for the superheroes to unite as a freelance, independent, 'charity' company. 2. **Superheroes, for the most part, aren't part of government and do not answer to the government.** This is very difficult to explain, but the only solution is to do it the way [Hancock](https://en.wikipedia.org/wiki/Hancock_(film)) does it. They simply refuse to allow themselves to be arrested. Like a parent feeding their kids vegetables, it doesn't matter what the kid (or in this case, government) wants, it matters what's good for them. 3. **Superheroes apparently, to some degree, can enforce the law and this seems to be socially acceptable.** Again, going back to the first part, while they do not need to work with the government, they *will* need government recognition. The answer to the first point also applies here. Enhanced people who want to become superheroes must be recognized as members of the law to enforce the law. 4. **Superheroes' secret identities may or may not be known to law enforcement.** There really is no way to explain this. They will need 100% to let the government know who they. They don't need to let the general populace know who they are, but the government does need to know. [Answer] There are many different paths your setting can take, especially if it takes inspiration from other fictional settings. Options for super-powered people can include: 1. **Joining the military/government (ex: Metal Gear Solid)**: Super people with powers for combat or working with military equipment (technopathy,mind reading to see what the enemy will do next, etc.) may join or be recruited by the military and government agencies. These super people could be seen as valuable and assets to any fighting force, allowing them to be recruited and treated well. They may even be put into certain positions of government that fit their talent if they do especially well and their powers help with their jobs. 2. **Can Enforce Laws To Some Degree With Citizen's Arrest (ex: Early DC Comics)**: Superheroes may not work with the government or military for whatever reason (maybe to guarantee their identity remain secret or a fear of government corruption), but they may still be able to fight crime and arrest people. Many people talk about superheroes being vigilantes and while for some superpowers this is true, that is not true for many. > > [Vigilante: a member of a self-appointed group of citizens who undertake law enforcement in their community without legal authority, typically because the legal agencies are thought to be inadequate](https://www.google.com/search?sxsrf=ALeKk0123UiExT5r_o8U7VRf5IrlDe4wGw%3A1597680137651&source=hp&ei=Cao6X8DtJZeNwbkPgYGw2AE&q=vigilante&oq=vigilante&gs_lcp=CgZwc3ktYWIQAzILCC4QsQMQkQIQkwIyCAgAELEDEJECMgUIABCxAzIECAAQQzIECC4QQzIKCC4QxwEQrwEQQzIECAAQQzIECC4QQzIICC4QsQMQgwEyAggAOgsILhDHARCjAhCTAjoCCC46DgguELEDEIMBEMcBEKMCOgsILhCxAxDHARCjAjoICC4QkQIQkwI6BwgAELEDEENQBljRCWCZCmgAcAB4AIABkQKIAfQJkgEFMC41LjKYAQCgAQGqAQdnd3Mtd2l6&sclient=psy-ab&ved=0ahUKEwiAlsWozqLrAhWXRjABHYEADBsQ4dUDCAk&uact=5). -Oxford Lexico > > > Now, the difference is that many superheroes still follow the law and work with officers to protect the people. Batman and Superman in earlier versions of their comics operated under a form of law where they could perform some version of [citizen's arrest: a rule where a person can arrest someone committing an active crime](https://www.law.cornell.edu/wex/citizen%27s_arrest). Any citizen can do it and the main difference is that a person performing it can only use it as an excuse if they are dealing with an active crime, which is what many superheroes do. Unlike a vigilante that wishes to replace law enforcement, these superheroes use their abilities to work with law enforcement. They help to perform a citizen's arrest, then go home. 3.**Vigilantism or Crime**: Some super humans might become vigilantes and take the law in their own hands or join criminal organizations. Some might even, if they play their cards right, become heads of a criminal organization or a local militia that patrols a community for justified (i.e. local law enforcement is owned by criminals, so the people need to enforce it properly) or unjustified (i.e. racist militia that harasses minorities). They may dress in traditional superhero garb or be more subtle. 4. **Normal life**: Finally, some super humans might just live a normal life and use their abilities/skills to do relatively normal jobs. ]
[Question] [ How would I change the evolution of humans to result in horns on humans as a result of reproductive fitness, instead of social fitness. Meaning, NEITHER "Horns are sexy", or some strange infection. Note: <https://worldbuilding.stackexchange.com/a/14907/6812> > > A predatory creature with claws and large teeth is unlikely to evolve horns. Unlike herbivores, carnivores have evolved to kill things, and don't tend to need to evolve extra weapons like horns. Furthermore, effectively using horns would require that the creature put energy into growing them, and into growing and sustaining the supporting structure needed to make them useful. Horned creatures need strong necks to support use of their horns, and the neck musculature wouldn't be critical to anything else for a creature evolved to run down and claw up its prey. > > > However, Hair is Keratin, Nails are Keratin, could hair evolve into horns? [Answer] Yes, horns are made of the same protein as hair and nails, so yes, humans (as mammals) have the potential to develop horns. The way to select for horns is to make them advantageous to survival. That *might* occur (over many millions of years) if humans, in order to protect territory (food source), were forced to fight for limited supplies **primarily** by head blows. If this were consistently the case, any mutation which would offer an advantage in head-butting competitions (thicker scalps, harder/thicker cranial vaults, better supportive structures for the brain protecting against concussion, etc.) would be advantageous and horns could reasonably be selected for. That's the only way I can imagine, and that's basically how evolution works: any mutation that offers a survival advantage is likely to be selected for eventually given enough numbers carrying the mutation. That explains why a mutation spreads through a population, be it deleterious (one sickle cell gene protects against malaria, but two copies of the mutation produces a disease that shortens lifespan) or beneficial (the continued production of [lactase](http://evolution.berkeley.edu/evolibrary/news/070401_lactose) such that people can continue to digest milk after infancy.) However, since humans have arms (both in the sense of appendages and weapons), such a scenario would be unlikely, but wildly inventive if convincing. [The Evolution of Horn-Like Organs](http://booksandjournals.brillonline.com/content/journals/10.1163/156853966x00155) [Answer] As anongoodnurse has already mentioned -- since humans have arms, it is highly unlikely that they will develop a weapon and all the necessary modifications just so that they can do their fighting by butting heads. So, since weapons are pretty much out -- how about **sensory equipment**? Unlike hair or nails, horns are NOT entirely dead material! Google "Broken horn" for goats, cows, or any other horned creature -- they bleed, they hurt, and they contain very well-circulated and sensory-rich tissue at the base inside! So, if you somehow manage to voodoo some kind of evolutionary necessary sense or skill located in this special horn-tissue, you've got a reason for humans developing horns. The ceratin layer around it (the visible horn) could then be either protection or a resonance space. And if humans need this special sense / instrument for mating, like e.g. sensing when a female is receptive or triggering ovulation, you'd even fulfill the 'reproductive fitness' checkbox. One thing they'd never do is fighting with the horns, though (no stags clashing in autumn...) [Answer] It *can* happen that hair mutates into, basically, nails. It is (thankfully) incredibly rare, and disturbing to look at the victims of this affliction (Google it if you're brave enough). However, humanity will not suddenly start evolving horns - there is no imperative for this, as well as requiring a tremendous number of changes for them to be "functional" (as you yourself list in your question). That doesn't leave room for a lot of options: **Change History** Simply make it so that our genetic ancestors developed these, and we kept them. Basically, hand-wave it into your story. For example: > > There once existed 3 species of human: Homo Sapiens, Neanderthals, and -name for horned humans here-. Of the three species only -name for horned humans here- survived into the modern age. > > > **Genetic Alteration** People get bored and start genetically modifying themselves. Something goes wrong (nanovirus, etc.), and *everyone* is modified to grow horns. People then kept them because women find themselves overwhelmingly attracted to horned men, and men will never willingly *lower* their chances at being found attractive. > > **Note:** Consider the implications of horns as far as modern military and safety equipment is concerned. If humans grow magnificent horns they will not be able to wear helmets very well. They might also not fit into cars, or fighter jet cockpits, etc. > > > [Answer] I know this is an old question but I'm looking for an answer myself... maybe confirmation of my own theory. I see no chance of humans developing horns as is. We've evolutionarily invested so much energy into making our brain our primary tool without investing into proper protection - the one we have is enough for the use of our head as main energy and sensory input device. Any advantage horns could theoretically give us would require significant changes to all the surrounding anatomy only to not endanger our brains. And even if you solved this question and equipped our muscles, skeleton, and brain cushioning adequately for functional horns, there's still the open question of their advantage to us. Arms have more reach, more mobility, hands can craft and grab dangerous objects to give even more reach, they're just so far superior, except maybe for stabbing other people, but brains and hands can craft stabby tools. So, if not as a weapon, and ruling out sexual selection, what else could their purpose be? ## Looking for a use If you look at horned creatures, they use all of their limbs for locomotion and they're herbivorous and basically have no other form of protection. Their horns are mostly a tool to discourage predators or used as weapon of self-defense should the attacker try anyways, or fight rivals for reproductive rights. Maybe to dig out roots or other food, but then again, we have hands... and the brains to craft the Bagger 293, try to outdig that one with your puny horns. ## Weapon? Now, considering our own evolutionary ancestry, we once were mostly herbivorous (or fructivorous to be more precise) and led an arboreal lifestyle. Go far enough into the past and our arms become increasingly used as a tool of locomotion and less for manipulation. Our brains were smaller and less important than they are today. So, maybe the ancestors of those horned humans led an exclusively arboreal lifestyle and had an advantage if they were able to use all of their limbs for locomotion, but still had to fight rivals to secure the right to mate. In come horns, not having to use hands as weapon could give them the ability to out-manoeuvre their rivals, but still attack, although probably only under specific circumstances; certainly a stronger neck, maybe also a longer one to increase reach and flexibility. I guess you'd have to go far back in time to make that a somewhat viable explanation. Later on the horns could merely be a remnant without any disadvantage and thus remain in one form or another, maybe over time the useful horns developed into a symbol of sexual selection, then they could remain viable to our horny Homos even when they develop into a detriment - male peafowl feathers have grown so large due to sexual selection, they've actually become a disadvantage when trying to escape a predator. ## Social RAMifications Our ancestors also grouped up to increase survivability, because they had no anatomic feature to defend themselves against predators - although some can be deterred by a good smack on the snout (sharks can and I think crocodiles, too) but I'd still not recommend trying to punch a lion's nose unless it's your absolute last option and you'd die anyway. A group of weak individuals can more easily overwhelm a stronger attacker than any single one could. It also helped develop our social behaviour; and our brain, finding out on how to work together requires brainpower after all. Maybe only the male (or female for that matter) individuals of the Homo Horniensis ancestors developed horns and roamed the forests solitarily while the other sex grouped up to raise the young and nurture their brains. I'd certainly be glad about a couple of dangerous spikes on my head alone in the woods with predators. ## Conclusion? In the end, if you go that far back to make horns a viable option and change all the variables required to do so, what environmental changes would then have to happen to force the hornys into the same evolutionary path we humans took? Take away the trees, okay sure. maybe make their main food source die out and their alternatives harder to reach to force their arms into a path of manipulation > locomotion. In the end though, I guess by that point you'd basically have to make the horns a non-functioning remnant, otherwise evolution would probably solve the obstacles we humans faced in a different fashion and you end up with a baboonicorn or somesuch. ## What about spikes instead? A different idea would be to give them spikes, like hedgehogs or porcupines have. After the forests dwindled and savannahs emerged around Cape Horn (yes, I know there's no savannahs there but there's also no spiky humans), our humans had already evolved bipedal locomotion, maybe even basic tool usage, but due to resource limitations shrunk in size (keyword island dwarfism). Now, large aerial predators hunted the pygmys, swooping down and snatching them up basically grabbing whole heads with their claws. With their heads most exposed and in danger not only helped their hair growing together into thin spikes blend in with the tall and dense grasses from bird perspective, they would also severly hurt the predators should those try to catch one, who didn't see the danger early enough to hide. I've heard porcupine stings hurt like hell, and they can detach and get stuck in your flesh... ouch. A bird certainly needs their feet to land, they can't limp like a quadruped can to releive pain in the affected limb or just lie down on the side. They'd certainly think twice about trying to catch another one of those little spiky human buggers should they get through the injury. Why the body size changes? Well, basically limitiations on the size of aerial predators. Even the largest birds to date couldn't snatch up a human. The largest extinct bird capable of flight? Argentavis Magnificens with a wingspan of up to 6.5m standing at human height size and weighing about 70kg is thought to have been mostly a scavenger. Pelagornis Sandersi with a wingspan of up to 7.4m but only up to about 40kg is thought to have been mostly a glider flying long distances over oceans and catch fish mid-flight with their "toothed" beaks. The largest bird of prey, the Haast's Eagle grew only up to 15kg with a wingspan of up to only 2.6m; it is presumed to have hunted the giant moa, much larger than a human, though didn't snatch them up. Then again, I guess that is already enough. You could also go wild and say the gravity of their planet is lower or its atmosphere denser and create monstrous flying birds. What is that, pterosaurs you say? Sure, some of them got much larger but like Pelagornis Sandersi they were gliders and either caught fish during their flight out in the oceans or the largest ones actually hunted on land, stalking the beaches where flocks of smaller pterosaurs nested and just prance about gobbling up any youngling out in the open in front of their terrified parents. Maybe that works, too ... [Answer] This could also occur due to benign tumors, as in the case of the Jackalope. No, I'm not joking, I'm actually being serious here. There are cases of rabbits that grow 'horns' due to a disease. The disease isn't harmful to the rabbits, who are able to live quite normally, however the disease is contagious which would explain why a whole civilization would have them. <http://www.isciencetimes.com/articles/5556/20130703/worlds-scariest-rabbit-horns-shope-papilloma-jackalope.htm> ]
[Question] [ I would argue that ants are one of the most dangerous, effective and successful creatures on earth. But as we know they are not the dominant form of life. They also vary through-out their many species; some have [potent venom](https://en.wikipedia.org/wiki/Paraponera_clavata) while others even have [acid](https://en.wikipedia.org/wiki/Formica_rufa). Many species are ferocious beasts alone but their true strength lies in numbers. The only true thing even able to wipe out a whole colony is [Cordyceps](https://en.wikipedia.org/wiki/Ophiocordyceps_unilateralis). Despite this they are not the dominant life form on earth, at least in the we are, but like robo-cop; We can rebuild them, bigger and better. What can I do to Legionary Ants (more commonly called Army Ants) to make them as dominant and successful as humanity? [Answer] Have the individual ants function as neurons in a mind that is made up of the entire hive. The intelligence is distributed throughout the entire hive and would work at the speed of pheromones (unless you want to alter the ants to have some kind of faster sonic or electrical communication). With an intelligence driving a hive the ants would be able to work much faster, solve problems and use more efficient hunting and gathering techniques, as opposed to the sweeping patterns they use normally. Such a mind would probably be incredible alien when compared to ours, and in credibly driven. The loss of an individual ant wouldn't affect it (any more than losing a single neuron would affect us) but large-scale loss could affect the hive's 'brain power'. Give the damn things an internet connection and who knows what this hive of inteli-ants might get up to. [Answer] Well, one simple way would be to provide them with the main thing that makes humans so dominant in the world: an intelligence. Not just a collective intelligence which allows them to live and function as a hive; nor a rudimentary intelligence, like leaf-cutter ants that harvest fungi from pieces of leaf or other species that have an arsenal of 'weaponry'; but a true, independent intelligence. You could even differentiate between a true ant and a smart-ant, where maybe normal ants live their normal lives whereas a smart-ant is able to communicate with humans (or any other sentient life-form) and thus rules over and commands the normal ants. An independent intelligence, such as humans have (or maybe even a few decades ahead of humans) may allow such insects to rule a technologically-advanced society, which would probably put them higher than humans. With respect to population, they already outnumber humans, so of course, the main underlying problem would still be their individual size... [Answer] The Argentine ant appears well on its way towards conquering the world. When introduced to new areas (generally by hitching rides on humans transportation) they steadily out-compete other ants and form super colonies that spread across hundreds, or even thousands, of square miles. At least one of these super-colonies has a population exceeding 1 Trillion ants, and there are several of them scattered across the globe. These ants are considered to be a pest. If the Argentine ants instead ate grain rather than other insects, they would directly benefit from the food production efficiency of the human race and would likely cause serious problems for the humans while their growth rate likely bumped up by several factors. [Answer] You can engineer a virus that will target ants and make them capable of these things : * Abandon living underground. * Craving for all sorts of flesh. * Become aggressive. * Coordinate with other ant types. * Accelerate the breeding process (many queens in one hive). [Answer] I'd say that there are two ways to go about it depending on your definition of a 'dominant species': 1) Human-like control over the environment- in order to mold the environment to their will in the way that humans currently do ants would need a larger degree of intelligence (possibly building on their existing hive structures) and a comprehension of tool use. Greater size might also help manipulate elements of the natural world but existing ant colonies achieve feats of tunnel creation and resource collection despite their diminutive stature. 2) Apex position in a favourable environment- plenty of animals have attained a position as top predators or an ability to out-compete most other lifeforms without distorting their environments to the extent that humans have done. Ants are often easily consumed due to their small size so you would probably need larger, more ferocious ants or less large predators to feed upon them. In terms of environment a tropical 'hot house' Earth would favour ants as they are more active in warm conditions and many species thrive in well vegetated climates. Arguably ants have gone further than many other animals towards both goals. Their nest creation and caste specialisation gives them a degree of control over their environment and the tools to deal with a variety of resources and challenges. As far as adaptation to the global environment goes they have a large combined biomass and can be found on nearly every continent. [Answer] The naive approach would consist in making them bigger, but it would require you to redesign too many things to be credible if you want to stick to biological plausability. However you can consider that the individuals of the species are composed of several micro-organisms (what are commonly called ants), as human bodies have several cells working together. The difference will be that ants are still able to live a few days even after being split from their "body", which is completely an advantage. Whith this increase in size, ants will be able to have a wider range of observation, and plan things on a larger scale. ]
[Question] [ I'm planning on sending a colony ship on an extended, multi-generational voyage to a distant star. My colony ship is an oblate spheroid, 2km long on its long axis and 1km across on its shortest axis. It's built using near future technology, with power generation provided by fusion plants and thrust via a large array of solar sails, which are mounted on external control pods and don't take up much of the 'internal' space on the ship. The sails can expand to an enormous area, but primarily use albedo changes to move around based on solar pressure, so their control doesn't heavily tax the power supply systems on the ship. Internally, I've got my power generation systems located along the central axis of the ship, with all technical areas and industry clustered around those. Following my industrial section, which must produce and recycle all goods for the populace of my ship, I've got habitation and commerce modules wrapping around the core in cylindrical layers, with farms and natural areas forming the outermost layers. I'm expecting the natural areas to be responsible for the majority of organic recycling and air filtration on the ship, though there is a backup system of atmospheric scrubbers to maintain a breathable atmosphere in the event of a biological breakdown in the nature modules. The entire ship is close to a zero-g environment, with the exception of several exercise modules, which generate artificial gravity by rotating around the rest of the ship. These gently rotate the rest of the ship, in accords with conservation of angular momentum, resulting in very gentle gravity acting on the rest of the ship, which leads to objects slowly settling towards the 'up' direction over the course of several minutes. The voyage is expected to take at least several centuries, so most systems on the ship will need to be replaced/maintained via onboard facilities multiple times. Technology has progressed to the point where the most space efficient way to handle this is by recycling all materials, rather than by carrying spare parts, though manufacturing methods are still broadly similar to what we have today, rather than using nanobots or the like. If I pack all of my essential systems in as efficiently as possible, about how many colonists can I expect to fit on board my ship? [Answer] # Food It may take 1 acre *on earth* to feed a single person, but that's relying on soil, sun, and animals. Cattle would be fairly inefficient to take in space, and you can't grow plants "naturally", so hydroponics makes much more sense. Since you have fusion power available, I assume hydroponic greenhouses can feed a human with much more efficiency than 1 acre per person. One source says it is about [10x](http://blog.alextiller.com/BlogRetrieve.aspx?BlogID=2729&PostID=54470) more water and land efficient. Also note that cows eat *a lot* of grain. One pound of meat requires about [10x](http://foodtank.com/news/2013/12/why-meat-eats-resources) times the water to produce compared to a pound of soybeans. It would be best if most of your population were vegetarian, unless population size isn't critical and you wanted the cattle for populating the destination (or as a luxury reward). # Shielding Also, it would be best to put as much stuff between your humans and the outside as possible. Hard radiation will make your ship pointless if the crew isn't adequately shielded. You can use water as a shield, or lead. But probably best to just put as much mechanical towards the outside as possible (but keep sensitive electronics near the interior). If your fusion reactor runs on D/T, then you can use heavy water as the fuel and keep that near the outermost layer. # Capacity One acre is about $4000 m^2$. Hydroponics can reduce that to maybe $400 m^2 \* 2 m$, so let's say $10^3 m^3$. Thus, you should allocate at least this much space per colonist. As long as their "personal space" is much less than this, that becomes mostly a rounding error, and the rest of the space can be used for power, life support, manufacturing/recycling, transportation, etc. So, absent a significant improvement in farming density, I'd say that $10^6$ is a hard upper bound on your population, and $10^5$ is more realistic (though anything in that range is passable). [Answer] (Adding onto o.m.'s answer and to try and answer ckersch's comment on it.) It takes about 1 acre to feed a single person based upon [this website](http://www.farmlandlp.com/2012/01/one-acre-feeds-a-person) which equals 4000 square meters. I assume this can be reduced because of two reason: 1. Advanced technology in comparison to the modern technology the website is basing their calculations on. 2. Reduced need for energy consumption (since they no longer will likely have reduced muscle mass based on [this question](https://worldbuilding.stackexchange.com/questions/36598/how-would-evolution-shape-humans-for-life-in-zero-g) about the same universe. I assume that $10^4$ cubic meters per person, INCLUDING food generation, would be more accurate for approximating the capacity, which allows for $10^4$ colonists instead, using the same space assumptions of o.m. (90% unusable space for engines/storage etc.) [Answer] The ship is approximately $10^9$ cubic metres. People can easily live in personal quarters with $10^2$ cubic metres per person. That would be roughly 33 square metres and 3 metres high. Of course people on Earth get out from time to time, walk in the park, so let me increase the volume by a factor of ten for corridors, gardens, etc. -- $10^3$ cubic metres per person. As a *wild guess*, assume that 90% of the ship are engines, storage, whatever. That would allow $10^5$ colonists. If you allow them less generous spaces, it could be $10^6$ or $10^7$ colonists. [Answer] The most efficient packing method would be if the colonists were liquified pre-flight, in which case each colonist would occupy roughly 60 liters of volume. An oblique spheroid as specified would have a volume of roughly 8.4 x 10^12 liters, so the answer to the question "How many colonists could fit on a 2km long multi-generational colony ship" is roughly 1.7 trillion. [Answer] To maximise the number of colonists and ensure that they arrive at their destinations alive, there is no better technique than... ## Suspended animation. By freezing the colonists into liquid nitrogen and later reviving them, there can be massive savings in space. Since there are no ambient heat sources in deep space, loss of coolant is not a significant factor during the vast majority of the trip, and therefore there is no need to carry excess coolant to replace natural boiloff due to heating. Assuming that the volume required to store an average colonist is equal to that of a [modern-day funeral casket](http://funeralplan2.com/askexperts/dimension.html) with volume ~=$\text{0.9m}^3$, you should be able to comfortably fit a billion colonists into the ~$1\text{E9m}^3$ of volume. The remaining ~10% or so of extra space would be dedicated to shielding, engineering and support for non-suspended crew members, who will treat it as a generational job to maintain the ship during the trip. Since the billion or so colonists are effectively maintenance-free cargo, the manpower required for running the entire ship would be minimal. In fact, it is possible for the entire thawing system to be automated, and in that case no thawed humans need be present on the ship for the vast majority of the journey. The technology to freeze a human into liquid nitrogen with minimal damage has already been pioneered by [Alcor Life Extension Foundation](https://en.wikipedia.org/wiki/Alcor_Life_Extension_Foundation), and as long as the technology to safely thaw out these frozen humans is perfected, this would be by far the most space-efficient way to transport colonists on multicentennial trips. [Answer] I have a book here somewhere written by Yuri Gagarin (the first cosmonaut) it says humans need 2 pounds of oxygen per day. I don't remember from the book anything about space required. But I do remember a debate on the news where they discussed prison overcrowding, and they determined that 17 cubic feet of air was required for each inmate for it not to be considered a health hazard. (0.481386 cubic meters.) (Round it off to .5 for easy math, and say you chose short people.) If the ship was only one meter wide and one meter tall.. then, roughly 4,000 people would fit front to back. Making the ship wider or taller would increase this number. But you would subtract for walls, fuel, engines, batteries, food, etc. 4,000 people at 2 lbs oxygen = 8,000 lbs per day. life support should have AT LEAST one day to spare! Liquid oxygen takes up less space, and would be the easiest way to transport it. The coldness of space makes refrigeration a little bit easier. 1 lb of liquid oxygen equals 337.56 liters (337,560 cubic centimeters). .. so 675,120 cc per person @ 2 lbs. x 4k people = 2,700,480,000 CCs. = 2700.48 cubic meters. So, if the oxygen tank(s) were one meter wide and tall they would would be 2.7 kilometers long (you wanted the ship to be 2km) Making them 2x high and wide (4x total) makes them 675.12 meters long. I would HIGHLY suggest a series of smaller tanks to keep liquid from splashing around during turns that much weight as a liquid could rupture the tanks from inertial force alone! and pressure at the end of a 2km tank during acceleration or deceleration would equal the force of a waterjet cutter! Imagine a cold-laser. Because you are using a sphereoid, I will cut it in half to do calculations of 2 domes (front and back) 1km wide 1km front to back. and 1km tall, the other domes height will make it 2 km tall and keep the same 1km dimensions on the other 2 axis. calculator tool @: <http://www.onlineconversion.com/object_volume_ellipsoid.htm> You have 1,047,197,551.1965976 cubic meters of space to work with. 3.7 liters of water/day (wikipedia), or 1.9 l/day according to the mayo clinic? call it 2 and recycle. Each crew/colonist would need: .5 cubic meters of space to live (cramped prison-style). .67512 cubic meters for oxygen .002 cubic meters of water (2 liters) - food? 2 liters as well. Imagine eating steak and potatoes from a cola bottle. .002 cubic meters of food. 1.17912 / call it 1.2 cubic meters per colonist. You could cram in 872,664,626 colonists if you did not carry fuel. (1/8 Earth's population?) But this is somewhat unrealistic. No batteries, electronics or machinery either. Average weight of a human adult...180? but their are children, being a generational ship. unless you want everyone in suspended animation, not needing a generational ship. Any more info you can give? I gave storage space for food, water, and oxygen for one day only, instead of for the entire trip, as food can be grown, and air and water recycled. ]
[Question] [ **Background** Tea has a magic to manipulate and control the *attention* of those around him. With this power, he could, for instance, hold or disrupt conversations, influence one's sensory perception to some extent, or possibly become a hitman.. But Tea wants to be a hitman like no other. Imagine yourself walking along a not-so-busy street going about your own business. Now pay attention to the amount of attention you would pay to a piece of stone that lay within your path. It is just so small a thing that enters your field of vision, yet it effortlessly escapes your sphere of attention. Just as how a small line of crack on the outside wall of a grocery store to your left did not escape your vision, yet it is so insignificant to you that you did not even venture to think how significant it is for a slightest moment. But at that very same moment you are walking along this wonderful street, Tea is also walking right next to you, holding up a handgun to your head at point-blank range, ready to deliver the blow at his convenience. You do in fact see Tea, just as you see that rock, or that crack on the wall. But Tea is able to make you pay as much attention to him as you pay to any of those mundane objects not worthy of your consideration. For him, what a hitman needs is not distance, but the lack of attention. For when an important person is about to be shot down by a sniper at the top of a nearby building merely knows that he/she is being aimed, he/she could easily duck below the window. Distance may achieve the lack of attention, but Tea can achieve the lack of attention directly, hence there is no need for distance. **Question** * If all Tea can do regarding his magic is to manipulate the attention of those around him, can he become a sniper in the fashion that was described in the background? If so, then there's another subtle point about the extent in which he can manipulate the attention. For instance, if Tea is being treated like a rock beside your feet, should would he still be able to hold this level of (the lack of) attention if he now completely block your vision by covering your eyes with his hands? If not, then why, and what else could Tea be? An option I could think of at the moment are lecturer and politician. [Answer] ## Tea would find being a short-range sniper difficult. There would be several key limits to his abilities, most of which stem from people being *unpredictable* > > Just as how a small line of crack on the outside wall of a grocery store to your left did not escape your vision, yet it is so insignificant to you that you did not even venture to think how significant it is for a slightest moment. > > > Perhaps you happen to be a painter or a building inspector and this crack catches your attention? A bouncer at a club or the President's bodyguard, people who are paid to be attentive, may still notice him. > > Now pay attention to the amount of attention you would pay to a piece of stone that lay within your path. > > > There's always a chance that your average Joe will trip on this piece of stone and fall, or by complete accident bump into Tea and come to realise what he's about to do - giving them opportunity to raise the alarm. ## Video cameras will still see him His ability to divert the attention of his targets would work at the time on that target. Somebody watching the CCTV footage from the camera outside the grocery store would assumedly be unaffected - they have a video recording of a man with a gun right in front of them. ## Difficulty may scale with number of targets It may be very challenging to divert the attentions of a great many people at one time, just as it's harder to juggle ten balls than it is to throw and catch just one. He may attempt to walk past a crowd with an openly held weapon and fail to distract them all for long enough to remain unnoticed. ## These limitations would combine to make him a poor sniper He may not be able to carry a weapon into the crowd at a speech, or walk down a busy street to shoot a man. He may have to rely on more traditional stealth and planning to make up for this. Maybe he could use his magic as a tool to make him an incredible thief or secret agent, where stealth is more traditional a weapon than distance. [Answer] Why would Tea even use a gun? It seems to me there are easier and subtler ways to achieve his goals: * He could just follow his mark, distract them at the right moment and have them run over by a truck as they walk into the road while studying a strange cloud pattern. Potentially the driver could also be distracted. **Advantages:** all his hits will look like accidents, making it a lot easier to escape unnoticed. **Disadvantages:** might be a bit more difficult to pull of on someone who is constantly staying indoors, but most people should be around traffic at least sporadically. [Answer] There are some questions that immediately crop up: **How powerful is this ability?** Could Tea walk the streets naked without anyone paying a blind bit of notice, or would he not get away with sneezing in a library without accidentally garnering unwanted attention onto himself? **What sort of proximity can this ability work in?** I'd assume pretty close quarters, because if Tea was a sniper, surely he could do the same distracting of targets from long distance through his scope? **Can Tea only direct people's attention towards/ away from tangible things,** such as stones or cracks in the pavement? Or could he cause people to focus on, for example, a task they are attempting to complete? Or divert people's attention away from the fear that they are feeling? Despite these issues, I still think that the best profession would be a **Spy**. He could be sat in the corner of a room whilst an incredibly important meeting is going on. So long as he is innocuous enough to not inadvertently draw attention to himself, surely he could just stay out of the way and ensure that nobody notices him whilst listening to an organization's super secret plans. He could also (possibly) subvert the fears of a contact in giving up information that they hold, or at least distract them enough that they relay additional information to him that they know. Garnering contacts would also be easier, as he could get them to focus on the horrors that a regime commits in order to get them to turn traitor and come over to his side. Following people to a meet/ drop off location would also be much easier. He could ensure that the target he is following would stay focused on their task, and pay no attention to the person following them, meaning he can discover enemy covert information and hideouts with ease. In addition, rather than being a hitman himself (I'm guessing once he gets his shot off in a public place no level of his ability would be able to keep people distracted enough to not realize that he has just shot someone in the back of the head), he could easily be a spotter for another sniper. He could blend into a crowd to get close to an intended high priority target, not necessarily stood next to them, but close enough so that his ability would work. Then he would cause them to lose focus, making them stop in bewilderment, at which point a sniper stationed 300 meters away would take the easy shot at a stationary target. This way, Tea could slip away unnoticed, whilst the sniper manages to escape from his perch. He could even distract any people who are after his companion, allowing his ally a little more time to escape from their position. [Answer] As already noted in the comments, a Sniper is someone who uses a rifle or other long-range weapon. the point of sniping is to accurately and effectively hit a target from a great distance, hard enough to ensure it stops functioning. That said, the ability to distract attention would be highly useful - a key part of being an effective sniper is not having your location disclosed. By distracting attention, one is able to effectively remove oneself from your nest - a highly attractive skill for the professional assassin. With that covered, an assassin with the ability to completely remove attention from one's self is covered already in fiction - so if you want ideas, read *Night Watch* by Terry Pratchett. Towards the end, using the exact method you've described - > > an assassination is carried out on the Patrician of the city in a crowded room. The target notices him, but nobody else does, even when the assassin dispatches two guards effortlessly. > > > (spoiler protected because it's an awesome book) It works a bit differently, as its not magic, more knowledge of the peculiarities of how Diskworld works, but the effect is the same. It does differ significantly in how it works as you described, but could be an interesting place to start :) [Answer] Skills like Tea's are versatile. Hitman? Sure. Sniper? Sure. Butcher? Sure. Elementary school teacher? sure. A general ability to control attention would be valuable for absolutely anything you could possibly ever want to do in your entire life. While the ability to walk about like you're not even there would be very useful for a sniper avoiding detection, there are many other essential skills for a sniper. Of course there's the question of aiming (and a corresponding question: can Tea control attention of those around him while trying to concentrate on perfectly aiming a gun, and firing between heart beats?). There's also discretion. I don't care how good you are at being undetectable. The soldiers a mile away that you're shooting at *will* notice a .223 round whizzing over their shoulder and hitting the wall behind them. Sure, he'd get away because people wouldn't pay attention to him, but he may have notified a more important target that there's snipers out there, and he probably shouldn't come outdoors until that's been dealt with. Could he do it? Sure. Why not. We haven't set any limits for what Tea cannot do. However, he won't be able to simply walk into a store, "borrow" a high power rife and a few boxes of ammo, and go off any target he pleases. Most targets worth sniping are aware that snipers exist, and will have structured their compound to make sniping harder. Also worth questioning: how powerful is this ability? If you watch documentaries on sniper training, those who spot snipers *are* aware of the small crack, or the small pebble. They may be particularly hard to fool. ]
[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/30902/edit). Closed 4 years ago. [Improve this question](/posts/30902/edit) On the rare occasion a vampire has a reason to willingly cause a human he feeds on to rise as another vampire, what possible method might he have to do it? I want to avoid the clichéd method of 'making the human swallow some of the vampire's blood before the human dies' (which isn't be possible for what I have in mind as vampires do not possess blood of their own). [Answer] **Teach it** The stuff about drinking blood is all a myth. In reality vampires drain the very life from their victims - drinking their blood just happens to be the quickest way to do it. The real secret is that vampirism is not a disease or infection of any kind, it is a supernatural teaching. Those who learn it became extremely attuned to their own life force up to the point when they sense how it slowly, inexorably escapes them. From then on it's only a short step towards various rituals that can transfer life from other sources... and the most efficient ways to do it are to tear it right out of other humans. So when a vampire decides to adopt a student, the teaching might start with repeatedly draining the prospect so that they will appreciate their life force more. Note that the student doesn't have to be a volunteer at all and the whole thing can take a form of dark seduction - will they learn, or will they die miserably? For some this is a greater tragedy than being infected by a monster - it is the knowing turning of oneself into a monster. [Answer] **Inject the human with the agent** When mosquitoes feed, they first inject an anticoagulant to keep the blood from thickening. This is what makes mosquito bites itch. If the vampire had an extra gland in the mouth, like a snake perhaps, that it could use to inject whatever agent causes the change, then it could turn a human without having to kill them. One bite, inject, and after the incubation period the person wakes up as a vampire. [Answer] **Feed repeatedly:** If you want to keep the nature of vampirism in your universe obscure (ie, not clearly magical or scientific), you could just require that a vampire feed from the same person multiple times while the person is still weakened from the previous feeding. **Storytelling advantages:** 1. **Flexibility with timing**. You could have the conversion take a dozen feedings over the course of a week, or three feedings over the course of a night. You can even make it take longer for stronger or "hardier" humans. 2. **It keeps the nature of vampirism obscure**. This feeding method could be caused by virus which requires a weak host in order to take hold, or it could be a mystical curse which requires that the human's *soul* be weakened. 3. **It could arise by chance.** If any human might turn after repeated feedings, it's imaginable that the first vampire[s] might have captured and fed on ancient humans as cattle, and passed on their affliction by accident. 4. **It gives a lot of room for tension.** A character could have a longer period of time to worry about conversion, wait for rescue, or plot an escape. [Answer] A mystical binding of the soon/recently departed soul to its mortal shell. Of course it will be part of the mystical rites that make the person a vampire instead of a ghost or ghoul... The rite could be something fairly simple but needing to make preparations would make it harder to be an 'accident'. [Answer] **Animals** Chinese and Slavic mythologies both thought vampires were created when [a cat or dog jumped over a corpse](https://en.wikipedia.org/wiki/Vampire#Creating_vampires).It needs a little tweaking to not be overly easy to do, but there are plenty of ways to adjust. Pick and choose as many as necessary from the below. * **Fresh Corpse**: It has to be a recently deceased body, maybe as little as a day or an hour. * **Cause of Death**: Only someone killed by an existing vampire can be brought back this way. * **Specific Animal**: Only a certain species of dog, or only black cats, will do. Maybe even only vampire cats or the Chupacabra can. * **Timing**: Only at midnight, or under a full moon, or during an equinox. * **Ritual**: After the animal jumps over the corpse, something else is necessary to complete it. Words, pentagrams, whatever. Most legends have a kernel of truth, so anything involving an animal that could have been misunderstood to be a cat jumping over a corpse will do. [Answer] **A Curse** There are a number of alternate ways based on various myths. Note that each region (and/or town) had their own mythical evil creature of the night. Bram Stoker simply aggregated a number of these and called the result "vampyr." The same sets of myths give us werewolves (Dracula can turn into a wolf). Most myths don't use blood transfer as the method of transmission. Most vampire types are created through curses. So, methods of getting cursed: 1. A witch - often when there were unexplained deaths in a village (disease) they would disinter the most recent corpse, "destroy" it and the look for a scapegoat to kill as the witch responsible for it. 2. Maliciousness of the vampire's mortal self - They brought it on by there own actions: gluttony, murder, etc. 3. A vampire calls your name from the city walls - actually the myths just have the victim dying but there's no reason they couldn't turn. 4. Unrequited revenge - "I'll get you if I have to claw my way from Hell." [Answer] ## A Deal with the Devil Vampires in pop culture(especially the new breed spearheaded by the Twilight series) are the results of a conspiracy by actual vampires; a kind of subliminal recruiting advertisement. The objective is to associate vampires with being "cool" or "romantic" or other positive qualities among the general public. This seeds the ground for the next step. In the next phase, they make use of their chief weapon of coercion, the predatory contract. This can take many forms, examples being a [hidden clause somewhere that makes you sign away your soul](https://www.geek.com/games/gamestation-eula-collects-7500-souls-from-unsuspecting-customers-1194091/) or borrowing cash from an oddly pallid Mafioso. Regardless of the exact details, it sets the victim/"new recruit" up for a visit from an agent representing Nosferatu & Sons Capital, here to foreclose your body and soul. Resistance from the target is unlikely to be effective because of incredulity("this can't be real right?") and/or strong positive associations("you guys are actually vampires?! awesome!"). Exactly what pop culture vampires were set up to do. Once the candidate has been locked in, the actual process of conversion is a combination of rigorous brainwashing, extreme ascetic practices([like seen here](https://www.youtube.com/watch?v=l6iAdM5K9Jo)), and body modification from specialists(the exact details are a blank for the OP to fill in). The candidate would be constantly encouraged along the way through Phil Jackson talks and MLM-esque tactics("Vampires are awesome right?! You wanna be a vampire right?! Then show your commitment by slicing out your kidneys!") [Answer] I also strongly disagree with these simplist concepts that either biting or making someone drink vampire blood will turn you into a vampire. The main problem I see with these approaches are the fact that vampires a quite powerful beings. So if you have a turning method that is this easy and with no drawbacks to the "master", vampire numbers in a given region should be alarming - which is a significant couterpoint, since they're, most of the times, depicted as outcasts that hide in the shadows for fear of being exterminated by humans. I would also like to state that I really like that old idea of a recently turned vampire spending a few centuries in service of a "master" who, ideally, acts as an afterlife guide, showing his new pupil the way into this gothic new world. All that being said plus the fact that you're giving us the opportunity to choose it (and other options have been taken by previous answers), I'm gonna go with a concept I came up with a few years back, called... ## Heritage Vampires grow stronger with age. As a rule, older means stronger. To turn a human into a pupil, the vampire must sacrifice a significant amount of his power - which is lost, given to the newborn. It will take decades, centuries even, for this vampire to regain this lost strength ('cause he will have to age these lost centuries invested in the creation of his "son") - which makes the act of turning someone an act of benevolence - the ultimate gift of power and immortality. The counterpart for the turned is that he is physically obliged to obey his master. No matter what is asked, the pupil must abide or something bad happens (up to you to decide what. In my case, unimaginable debilitating pain). This servitude, however, will come to an end. As time passes, the power the master has over his pupil continuously decreases. This happens because, as the master regains his strength, this "seal" that bonds master and pupil gets weaker, meaning the pupil starts to "have a voice". The physical pain will get proportionally weaker as time passes, until the master is "complete" again (meaning he has regained all the power lost in the turning process). At this point, the pupil is completely free. Also worth noting that, if the master desires, he can set the pupil free at anytime, but only if he truly wishes to do so (can't be coerced to do it). [Answer] You say you don't want to go with the *classic* method of the human feeding on the vampire's blood and say it's not even possible anyways... but why not? The blood in the vampire's circulatory system doesn't have to be their own naturally generated blood. In fact, one has to consider: why would an undead immortal need to feed at all? The blood being drank has to fulfill some need, especially since the vampire wouldn't have a working stomach to digest the fluid. Obviously the blood in a vampire's veins is blood obtained from former meals and drinking human blood helps replace the expired "coolant." Since this blood is able to convert humans to vampires, we need to understand how. The best answer would be a chemical agent in the blood or a viral agent that infects the host. Both possibilities could give way to alternative methods of infection. First, the chemical agent. Vampires are eternally their age (in most depictions), highly resilient, and [know kung-fu](https://tvtropes.org/pmwiki/pmwiki.php/Series/BuffyTheVampireSlayer). The easiest way to explain this is their bodies are somehow producing a chemical that allows them to have these features. (In the case of Kung-Fu, obviously their reaction speeds are being heightened and these instinctual movements *clearly* just *look* like Kung-Fu and aren't *really* the same art... or humans learned kung-fu from vampires. One of the two.) Since it's a chemical and not a biological agent (like a virus), any means of "feeding" this to a human should have the desired effect of turning them into a vampire. This can probably be done based on the themes you're aiming for. If your story is meant to be a romance, kissing/salivary transfer of the agent could result in a gradual process of transformation. If it's meant to be more... adult. You could have [*the less "family-friendly" kind of embrace*](https://tvtropes.org/pmwiki/pmwiki.php/Main/UnusualEuphemism) be a means of pretty much guaranteeing transformation so long as some of the fluid is ingested. If you want to go with something less romantic or sexual, you can use a serum formulated from a vampire's bodily fluids (sweat, saliva, blood, whatever) that can be injected to perform the transformation. Additionally, if magic is in this world, you can use a spell or a Deal With the Devil, but that doesn't really fit either of these categories. Just be sure if they do the latter, [they should be deterred from any *very enthusiastic* walks at any cost.](https://tvtropes.org/pmwiki/pmwiki.php/WebVideo/HellsingUltimateAbridged?from=WebVideo.HellsingAbridged) If it's done through a viral agent, it could be that merely biting the human risks them getting infected. Viruses have an easier time infecting people who are weakened, and being near death is a classic way of weakening someone. It's a classic trope for the [dead](https://tvtropes.org/pmwiki/pmwiki.php/Anime/DragonBallZ) or [nearly dead](https://tvtropes.org/pmwiki/pmwiki.php/Manga/OnePiece) to [come back stronger](https://tvtropes.org/pmwiki/pmwiki.php/Main/CameBackStrong), after all. Having a reason to explain why makes it that much better. That said, depending on the human, it's possible they've developed a resistance or immunity to the virus that prevents infection. In that case, you may want to take the path of HIV/AIDS and make the virus a retrovirus that is hard to fight off. This could give other, interesting societal implications as well by bringing up the question of "are vampires really to blame" and "shouldn't we find a cure instead of killing them?" As for transmission, you can use any of the aforementioned transmission methods. It could even be that any contact with infected fluids can cause the transformation, so vampires prefer to kill their victims outright instead of trying to keep them alive since it means more predators feeding on prey for survival. ]
[Question] [ The [language](/questions/tagged/language "show questions tagged 'language'") tag challenge did remind me something which always baffles me on "Star Wars" franchise: Why on Tatooine would intelligent androids use beeping for communication? So I call you, fellow Worldbuilders to help me create more plausible Star Wars droid: **What language would droids use to communicate with each other?** Except usual Star Wars universe please accept these assumptions * The droids are created on many planets * Android creation is relatively easy. Even 9 year old kid can build a droid * The droids are compatible to some extent with regular ports (especially these used by Imperium on Death Star) * However, you cannot connect "port to port" if you are in hurry * Any droid can produce any sound which is inside human audible spectrum * However, that's their only way of "ranged" communication. They do not have radios or lasers (except when equipped with blasters) and cannot produce "sound" outside audible spectrum * A droid will meet other droids regularly and need to interact with them The androids are "general purpose AI" by our standards and are able to learn in same (or faster) pace as normal kid. Also, it is safe to assume that just built android comes up with standard OS (Android, probably? Pun intended) preinstalled. While droids can communicate with their masters, I think that to communicate amongst themselves, they would eventually come up with some language. But would that be beeping? Thanks for help and if you feel giving this question better title, feel free to do so **EDIT:** After first two comments, just for clarity: I am not asking why is R2D2 beeping. I am asking if any Star Wars android would beep given assumptions above [Answer] **Remember dialup?** [![enter image description here](https://i.stack.imgur.com/VZBzY.jpg)](https://i.stack.imgur.com/VZBzY.jpg)[Source](http://www.windytan.com/2012/11/the-sound-of-dialup-pictured.html) If the droids can only communicate with each other verbally, that is, with vibration in atmosphere within the human audible range (pretty speciest if you ask the Wookies), then they'll use highly complex words. Something similar to those tones your modem played when connecting to the internet or fax machines. These words will be composed of modulated data on a wide range of audible frequencies simultaneously. The best way to imagine this is listening to someone with a very low voice and someone with a very high voice speak at the same time. The android is capable of filtering the incoming audio based on frequency and then demodulate them. There has actually been work on this. Even work trying to make it sounds nice by playing with the modulation parameters. [This paper](http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.422.2213&rep=rep1&type=pdf) reports on some audible communication reaching maximum rates of 3.4 Kbps using FSK (frequency shift keying) for a single carrier, which they improved in a few ways, even human perception of it: > > The novel idea in our work is to study how music and other > pleasant sounds can emerge in the audible band by carefully choosing > some parameters of the modulation. By doing so, we surpass > the low data rates imposed by imperceptibility while preserving the > property of using messages that are tolerable to humans > > > By using ASK (amplitude shift keying) and some other fancy tricks they can get up to 10 Kbps on the higher frequency channels. While the droids could feasibly use much better modulation schemes than simple FSK or ASK to get significantly higher data rates per channel, even using this method to transfer data on perhaps ten simultaneous channels, they could likely get well over 75 Kbps. It's probably enough for standard communication. [Answer] I don't think this is as tricky as it sounds: **1. Android to Android Communications** They are machines that think at blindingly fast speeds. Expressing their ideas (which might be system data, binary, etc) in a SPOKEN language is ludicrous. That was done simply because it's a movie, and the droids had to be "cute" for the audience. In most likelihood droids would communicate via wireless transmissions, laser pulses, or some such manner (bluetooth, etc) which has nothing to do with having to "speak". A standard communication protocol would be in effect. This is basically the internet. Billions of different devices communicating with one another over a vast network. **2. Android to Human** Some droids need to interact with humans, others not so much. That little box on wheels that cleans the floor wouldn't need to speak to anyone, or even be capable of complex thoughts. C3PO is an ambassador droid, and knows a ridiculous number of languages, as well as being able to communicate with other droids. R2D2 doesn't really need to "speak" to people. He would normally spend most of his time plugged into a space craft - outside the cockpit. No one could hear him speak, even if he tried. Thus, he wasn't taught "a language", even though realistically, he should have been able to communicate verbally when on the ground. We can assume that he communicates with the pilots via displaying information on their visors while in flight (targeting data, ship management parameters,etc) --- **Edit based on new criteria:** I honestly *do not think it is reasonable* to exclude wireless communications, or laser based communications (not blasters). Advanced technology basically can't exist without wireless, and we see many examples of such communications (interplanetary, across solar systems, etc) in the movies. As I commented below, the only situation in which a droid might not be able to communicate wirelessly would be that it is damaged, or restricted from doing so due to situational (battlefield) conditions. At that point laser based communications would be critical. Excluding even laser communications, however, beeping might make sense. A fast-forwarded binary type of communication based on "long" and "short" (on their scale, not for human ears) beeps. It would be horribly inefficient, and painful for any human listening to them, however. [Answer] "D" Latch, common and encrypted digital, and modulated with analog over vast areas. Your holographs were good, your voice communications were pitched with spikes, and Johnson's WHITE noise, and the glitches were shoddy at best, even STAR-WARS had that favor. :) [Answer] Sound can be a useful way of transmitting data. We've been using modulated sound waves to send data down telephone lines for a while now via modems. The problem with sound is how quickly it can be modulated and still have the pattern recognizable. You could improve this by not using a base 2 binary signal, and instead use overlapping wave patterns to transmit a higher base system. There is also the problem of loud environments, but certain frequencies of sound would be able to cut though that with little trouble. There are a few companies out there playing with the idea of [transmitting data with sound](http://venturebeat.com/2012/01/10/sonic-notify/), and I've heard of a [computer virus that spreads with sound](http://www.newstatesman.com/future-proof/2013/12/researchers-prove-pc-viruses-can-spread-microphones) to infect airgapped computers. Radio is superior to sound in almost every way: \* It's longer range \* It works through walls \* It's harder to jam \* It works in loud environments \* It's faster to modulate, meaning you can send more data quicker But in the absence of radio it wouldn't be to bad, and could realistically be used for simple command communication, which is what a droid to droid conversation would most likely be about, unless you have a droid file sharing network... **Edit:** So interesting article I read about data transmission through [visible light, called LiFi](http://www.ibtimes.co.uk/lifi-internet-breakthrough-224gbps-connection-broadcast-led-bulb-1488204). The tl;dr version is that with distances of about 3 meters you can get data transmission speeds of up to 224 Gbps, which is an order of magnitude faster than WiFi. Their real world examples transferred a 1GB movie in 1 second. One other possible advantage of this over WiFi is that it could be directional, and so a little more private. So that little blinky light on R2? High speed inter-droid communication. ]
[Question] [ How would Roman Warfare have changed if they actually had legendary 'flexible glass', and it was cost-effective? [Flexible Glass (vitrum flexile)](https://en.wikipedia.org/wiki/Flexible_glass) It's an unbreakable, and I mean **literally** unbreakable, glass. Assume that it looks and acts like normal Roman glass, so an enemy could melt a hole through it, if they wanted, and can be made at about the same price, but it just can't shatter, and instead dents like brass. If you can make glass, you can make vitrum flexile, with just the addition of some additive, which Rome won't run out of. Could you make city walls out of the stuff? [Answer] As has been said, it's just armor. Why would you bother with making something like city walls out of it? Now, there's one thing worth making out of it--helmets. Back then you could choose protection or visibility, not both--and even if you chose protection you could die of something through the eye slit. A helmet of this material would have no eye slit. [Answer] [![Riot shield](https://i.stack.imgur.com/M5Wdg.jpg)](https://i.stack.imgur.com/M5Wdg.jpg) Since one of the Romans preferred fighting techniques were the [shieldwall](https://en.wikipedia.org/wiki/Shield_wall), a large improvement would be to have a shield that you could see through. Giving the opportunity grab the opponent and stab him, so on and so forth. [Answer] It might make a reasonable material for armor. It would presumably not rust, so it would be easier to maintain than iron or steel armor. It would also presumably be lighter and less likely to break. So, "**more armor**"? It might also be useful for creating armoured warships with lower drag than with wood, but I doubt it would have occurred to the Romans. While their naval technology was probably decent, they had several centuries of minimal need for improving their warships. Maybe if somebody had realized that making the entire ship of the glass would make it have **much** longer lifetime and possibly make up for the higher initial cost. [Answer] They could pound it into various useful forms such as magnifying lenses, then assemble them into telescopes to see the enemy at a distance. Glass is nearly invisible underwater, so sharpened spikes of flexible glass mounted in all of the shallow points on a river would effectively block and possibly maim anyone trying to ford across. The same thing could be done along any ocean or lake shorelines. [Answer] ## Walls As a wall it would be decently strong if you put a barrier of some kind behind it you could easily make it similar to a normal wall. Although unbreakable doesn't mean it cannot be either dug under or scaled so it wouldn't make much of a difference. ## Armor As armor there are a few interesting thing you could do with this. As someone mentioned before, a see through helm would be a great tool. Honestly though why stop there? a see through shield would be a great tool as well. The main problem would be that the user of the armor could still be killed. there would have to be breaks in the armor to allow for mobility and the fact that it dents means that a blunt weapon could be an effective means of countering this armor to some degree. having unbreakable armor like this could mean that certain tactics like the phalanx (basically a wall of spears to counter cavalry and charging armies.) would be much less effective. ## weapons Having see through spike in shallow water is a good idea but to expand further on that idea previously mentioned by Henry it might be an effective means of guarding coastal cities from naval invasions. Weapons made from this materiel would probably be as good as any other metal they had at their time considering how it bends. It may be a better option to stick with steel swords. All in all it is a strong defensive choice but not necessarily a strong offensive choice. ]
[Question] [ I am using the same androids featured in [this question](https://worldbuilding.stackexchange.com/questions/26300/how-would-the-widespread-creation-and-use-of-androids-affect-warfare) **Android Details** * Roughly 10 times stronger than the average human * Possibility to reach maximum speeds of 64 kmph * A breakthrough (possibly some form of [programmable matter](https://en.wikipedia.org/wiki/Programmable_matter)) has allowed us to quickly and efficiently mass produce them. * My androids use advanced AI. They are capable of handling all basic battlefield tasks without human supervision, and the high command is comprised of cyborgs with increased mental capacities. Only human interference required is to give general orders (e.g. 5th Battalion should proceed to point xy of battlefield and hold position). **Other details** * This is sometime in 23rd century. While we have colonies on Mars and bases on various bodies in our solar system, they are mainly self reliant and do not fall under the jurisdiction of Earth governments. [The United Nations became inefficient in in late 21st century and ceased to exist during the mid 22nd century](https://worldbuilding.stackexchange.com/questions/26302/how-can-i-realistically-dissolve-the-united-nations). * The richer nations, such as the (fictional) Black Sea Union, European Union, United States of North America, the New Japanese Empire, Russia, and the New Islamic Caliphate rely heavily on Androids. The Chinese use Cyborgs (humans with cybernetic implants) to take full advantage of their relatively massive populations. The poor third world (see present day third world) have primarily human militias augmented by cyborg mercenaries. * Conflicts regularly occur in border regions, although full scale war has only happened twice so far, about once per century. It has crossed my mind that the goal of a war between the major powers where, for the most part, casualties would be very little, regular tactics would not work. The goal would go from being "kill and maim enemy soldiers to demoralize enemy civilian population" to something along the lines of "destroy more of the enemy droids than they can build." **How would the tactical and strategic goals of generals differ from what they are now?** [Answer] There are a few major issues here that will affect tactics. 1. No more surrender. The androids are not going to surrender if encircled or outnumbered — they will fight to the death. This is generally going to result in heavier “casualties” all around. 2. Production plants become major targets. If you’re fighting against android armies, you need to destroy or slow your enemy’s production capability ASAP. These will be major targets for airstrikes. More powerful countries may attempt to build these underground, but it seems very likely that the size of facilities required would be impractical to build in bomb-proof bunkers. Defenses around these facilities will be very impressive, particularly the anti-aircraft weapons. Attacking the supply lines providing resources to these facilities will be another strategic option if they become too heavily defended. 3. Suicide missions. The only things lost when an Android dies are resources. This is actually a rather extraordinary advantage, since it removes the moral cost of sending large numbers of soldiers into tactically questionable circumstances. Penetration of defenses to high priority targets can happen much more quickly if your soldiers don’t need to get out. 4. Difficulty protecting civilians. With that kind of strength and speed, these androids don’t even need to be armed to pose an unprecedented threat to human beings (even soldiers). They will be difficult to target, harder to kill, and very, very effective at killing people. Frankly, without androids present to defend them, it’s unlikely that any targeted humans would even survive. When coupled with the new suicide tactic, high-priority humans - such as leaders - would be very vulnerable. Without androids at their disposal for defense, they would need to surround themselves with structures that minimized the effectiveness of the androids’ maneuverability and strength. Bear in mind, however, that direct combat between these powerful nations is unlikely. Weapons of mass destruction will continue to be a major deterrent, particularly with another 300 years of technological advancement. This means that these androids are most likely to be deployed against nations and militaries that do not have android armies. Needless to say, that won't be much of a fight. [Answer] **Deniable invasion:** Currently when an invasion occurs is hard to hide which nation’s troops are involved. Russia tried to hide its invasion of Crimea but photos linked their troops to Russian military parades and captured troops can be interrogated. If you duplicate another nations Androids you can change their paint scheme and attack a neighbor and claim you had nothing to do with the invasion. This allows you to invade a nuclear nation without them being able to learn who to nuke to stop the invasion, similar to cyber-attacks today. **Speed of mobilization:** normally to mobilize a large army a nation must spend many weeks and months to train troops before they can deploy, us army basic is 10 weeks, the time increases as complexity of tec increases. Androids are ready to fight instantly. The speed of a nations mobilization is only limited by industrial capacity, a nation could go from pacifist to largest army in a day. Nations must keep large amounts of spare production capacity for mobilization. **High accuracy:** Robots are really accurate shooters. Most of human inaccuracy comes because our fine motor control is only accurate to within a few millimeters and against a moving target our reaction time is a few milliseconds. A robot can archive precision to a few micrometers and reaction times in microseconds or sometimes nanoseconds. A robot is terrific shot, what currently holds them back is the image recognition problem of identifying the target. As far back as the first gulf war a computer targeting system could hit an enemy tank moving at 60mph on bumpy terrain from a tank moving at 60 mph in bumpy terrain from several miles away. **Reduction in Civilian casualties:** For the first time in history would be able to clearly delineate between civilians ( humans) and soldiers (androids). With automated factories producing androids killing enemy civilians would in no way cut down on the enemy war effort, and there would be no fear they would later become troops so there is no reason to kill them. As the robots with be accurate enough they are only likely to hit each other and other important targets. **Increase in war tempo:** Human troops need to stop and sleep eat and so on. With caffeine and other stimulants troops can keep fighting for a few days in a row but robots can fight 24/7 **Focus on cheap troops:** War becomes economic. Androids are expendable. If two nations have similar resources if one can kill 2000 dollars of enemy androids with 1700 dollars of their own will win. You can win by just running the enemy out of money. It would be a normal and valid tactic for a cheep drone to sacrifice itself to kill a expensive drone. This is already happening the US is researching very cheap weapons to kill very cheap drones. [Answer] **They wouldn't change all that much compared to what they are now.** Acquisition of territory, political power/concessions, food, resources, manpower, reproductive power have the been the aims of conquest and warfare for millennia. Why would it be any different 200 years in the future? (This answer is different. There was another question related to weapon design and I answered in the wrong place. Sorry.) [Answer] My answer will only address the tactics around producing the androids. I would think the specific battlefield tactics would stay much the same as they are now. A strategic military target will still be a strategic military target, as defined by the commanding officers and aims of the war. On the other hand, you've got a programmable matter assembly line that allows you to easily produce complex robotics with incredible ease and in a short time. That's an incredible advancement, and probably the most important piece of information. This means local battlefield skirmishes are going to be about *form*, essentially a type of arms race. I imagine the largest part of the military will actually be the designers and engineers constantly coming up with new forms and weapons for androids. Here's a small possible example: 1. Military powers start off using bipedal humanoid androids. 2. One army starts producing arachnid-legged androids that can easily scale walls and in urban settings attack from virtually anywhere. 3. Countering army develops android with 360 degree visual sensors and highly rotational limbs that allow easy attacking of a target at any position. 4. Arachnid army discovers flaw in sensor-bots and it exploits it with a sensory-overload light device that freezes up sensor-bots in battle. This could continue *ad infinitum*, until you've got a huge army of different types of androids with different purposes. Some will be there to specifically target a weakness in another bot, some will be highly efficient at a given task (stealth, sniping, brute force/tanking, specialized to environment, communications interception/disruption, distraction, different sizes, etc.). So, not only would the designers and engineers be a huge part of the army, but they'd be one of the most valuable assets and thus targets. Rather than out-producing enemies in numbers, the race will be to out-produce enemies in designing the most effective forms. Armies will want to delay their enemies' production by destroying, infiltrating, or giving false data to research and development facilities. Because of this, I see the nature of the R&D facilities needing to change. Instead of being centralized think-tanks, teams of developers would work in cell-like arrangements, working independently. That way if one was taken out, spied on, or given incorrect schematics on an enemy android, it would only affect a small part of the military's operations. Now, even if you're set on only androids with the specs given in the original question, I believe this answer would be much the same. If the entire shape needs to stay generally the same, some small modifications should be able to take place that still make it a game of one-up-manship. One army creates thicker body plates, so the other makes penetration rounds. That gets countered by re-configuring internals to have less critical-failure points. That in turns gets countered by spray-tactics or explosive rounds. So on and so on. [Answer] In a word with mechanical soldiers, human-like androids would only be useful for cleaning up the urban area. In field combat, in desert or steppe automatic vehicles would be much more useful. Moreover, even in urban areas I think, light-weight flying drones or microcopters would be much more useful. So in general, androids well, would be the most useful for parades, and the majority of robots in the battlefield would be robotic vehicles and drones. --- Obviously if the majority of warfare would be in "proxy-war" mode (given that nuclear weapons still exist), the tactic for the "government" army would be as it is currently - to inflict the most casualties on the "rebels" (who are still using human armies) and clean up the territory. The tactic of the rebels would be terrorism against civilians, disguise themselves for civilians, diversions, using cheaper drones of foreighn build. [Answer] Depending on the type of war/skirmish, things could get real nasty, real soon! # Open "Honorable" Warfare We are talking about soldier versus soldier battles here. Of course the droids would have a lot of edge against human soldiers *if* it came down to gun battle (worse, if were a one to one fight body fight where droids would put whole battalions to extinction within minutes). But here we are forgetting the role of so many other things, specially light armored vehicles, tanks and helicopters. One tactic against droids could be the use of water cannons. Since droids are primarily a combination of electronic circuits and motor parts, short circuiting them with powerful water cannons would be their certain death! Another tactic useful here is the use of [EMP bombs](http://www.digitaltrends.com/cool-tech/us-air-force-confirms-boeings-electromagnetic-pulse-weapon/). Killing their circuits all in a flash, these devices would highly favor human soldiers in the battleground. Furthermore, device jammers can be effectively used to disrupt communication between a droid and it's command center, making it easy to bring it down. # Covert Operations Droids would be extremely useful in assassination and sabotage. No doubt about that. How are you going to stop a medium sized, extremely intelligent robot, that can climb walls, shoot without missing and run at 60 km/h? The above mentioned tactics would be very useful in a battlefield, but less so in passive defense (protective measures to discourage an assault). The main anti-droid defenses installed in buildings compounds would be very high frequency machine guns, controlled by computer. That, and everybody would have to walk through metal detectors several times at security checkpoints. # Urban Warfare Here the true power of droids would be unleashed. Fast, precise and able to dismember a human within seconds, these war machines would be unstoppable. The assaulting party would have a high advantage against defending party even if both are using equal number of droids at the same level of technology. The advantage being that every infrastructure damage caused by the offensive party would count against the defender. Furthermore, for the assaulter, everybody except their own men would be a target. A city block where 10 droids battle it out to death for 15 minutes (5 per side) with grenades, mini-missiles and SMGs would look like a pack of angry T-rexes had their way with the place. [Answer] Unfortunately the outcome in real life will be much more bleak than traditional thought on military strategy and planning. That's because ever since WWII for some reason most people have WWII tactics and strategies in mind. The real war lessons are learnt in the past more recently since then, as just a couple of examples: a) Falklands War b) Cold War In the Falklands surface ships were suddenly discovered to have no defence against both submarines and missiles - after catastrophic, non-defensible losses they were then (on both sides) parked. The lesson here is don't assume current methods to be useful, even if historically they were so. In the Cold War a hidden unknown threat that could be imminent (for instance 20 minutes from launch to detonation) rendered most 'war' obsolete because of complete potential destruction. The only 'wars' since then are more just battles in comparison, usually a large force against an ineffective non-nuclear armed one. The use of drones is common now, and it will get worse. However, now we have computers that are faster, and methods of programming that are more organic and dynamic. Combined, AI and drones will be a lethal as there are no qualms about their use unlike nuclear weapons, and citizens in an attacking country would be virtually unaware an offensive would be happening. BAE Systems for instance is working on drone submarine aircraft carriers carrying drone aircraft - without human intervention or control. All you need to instruct is 'go to this place and keep launching attacks' - it would be devastating, yet impassionately carried out. There is really no use for 'androids' - why would you restrict yourself to inefficient bipedal constructs that hug the ground, when you can simply send a swarm of millions of aerial or torpedo drones, each one armed with an explosive? Each is cheap to make, and in a dispersed cloud virtually unstoppable. There is no defence to this, except a nuclear deterrence. In your scenario, androids would quickly become obsolete as they would be inclined to fly, lose their inefficient quadrapedal limbs, become simpler just so they could be more numerous. They in essence will become like drones of today, but with autonomous AI and armed. As future production facilities could also be autonomous numbers can be produced for no real cost other than the small amount of resources needed to create one. Arsenals will be assembled similar to nuclear arsenals of today, in a new arms race. Unfortunately, this bodes ill for human residents no matter if you're on the attacking side. We are slow, awkward and defenceless against a swarm of millions (if not billions) of drones. Even underground would be no defence as it is easy to send drones burrowing through the ground - imagine the planet riddled with trillions of them. Let's all just hope that no reasonable human would embark on this path in the first place. [Answer] If the humans run the government and, through the government, the military, then the humans will be the targets of the weapons. Consider the American Civil War and Sherman's March to the Sea. Many people in the South supported the war, but didn't know any of the horrors because it was miles away and the news media was limited. Gen. Sherman brought the cost and some of the horrors of war directly to the civilian population and the industrial centers. Two sets of android armies could fight for years on some battlefield and the civilian population wouldn't care, unless the civilians have to pay massive taxes to support the war. Thus winning the war would depend on forcing the human government to surrender. If the human government is a democracy like the CSA, then an army can use property damage to demoralize the voters, damage the industrial capacity and bankrupt the financial support of the war. Suppose that the human government is a dictatorship with no regard for their fellow humans. In this case the head of the government is the biggest target. The android army would be used to attack the industrial centers and the dictator. Depending on how the dictator is killed, their successor will have to decide to continue the war and risk the same death as their predecessor. ]
[Question] [ First, is it possible for a planet hit be a meteor to shatter into two pieces?. Then, can the two pieces remain in orbit? Especially, can they develop a sort of co-orbit around each other? [Answer] I like [TimB's answer](https://worldbuilding.stackexchange.com/questions/14673/can-a-planet-hit-by-a-meteor-shatter-into-two-pieces-alternately-if-not-a-mete/14675#14675) discussing the [Giant Impact Hypothesis](http://en.wikipedia.org/wiki/Giant_impact_hypothesis). I see that in [a comment on his answer](https://worldbuilding.stackexchange.com/questions/14673/can-a-planet-hit-by-a-meteor-shatter-into-two-pieces-alternately-if-not-a-mete/14675#comment35701_14675), you wrote > > Thank you! I actually had this Moon origin theory in mind. But I'm actually wondering about an inhabited planet, in the immediate run. Is there any possibility of survivors, say, after the shattering? For a while, at least? Any idea? > > > The answer is most certainly no. I'd like to go in-depth as to why that won't be happening. In [an answer to one of my questions](https://worldbuilding.stackexchange.com/questions/13267/how-can-i-set-a-moon-on-fire/13277#13277), Serban Tanasa discussed the conditions of impacts. He cited [Stewart et al. (2015)](http://www.hou.usra.edu/meetings/lpsc2015/pdf/2263.pdf) (which cites an earlier work by the three, [Stewart et al. (2014)](http://www.hou.usra.edu/meetings/lpsc2014/pdf/2869.pdf), giving the formula for the energy released in an impact, $Q\_S$, as $$Q\_S=Q\_R(1+M\_p/M\_t)(1-b) \tag{1}$$ $Q\_R$ is calculated as $$Q\_R=\frac{0.5 \mu V^2}{M\_p+M\_t} \tag{2}$$ In this latter paper, they mention that for grazing impacts, $b>\frac{R\_t}{R\_t+R\_p}$, so we'll assume here that $b<\frac{R\_t}{R\_t+R\_p}$. You mentioned a meteor. A meteor will do next to no damage to a planet. In this case, $R\_p \ll R\_t$, so we're left with $b<1$. To do some *real* damage - enough to do what you want - we need $R\_t \approx R\_p$. So $b<\frac{1}{2}$. We can, though, say that the projectile isn't *too* massive. We'll toe the line and have $b=\frac{1}{2}$. Assuming the densities are the same, $R\_p \approx R\_t \to M\_p \approx M\_t$. We now have $$Q\_S=Q\_R(1+1)\left(1-\frac{1}{2}\right) \to Q\_S=Q\_R$$ This means that $$Q\_S=\frac{1}{4} \mu V^2 \tag{3}$$ $\mu$, the [reduced mass](http://en.wikipedia.org/wiki/Reduced_mass), is $$\mu=\frac{M\_pM\_t}{M\_p+M\_t}$$ Assuming both bodies are Earth-like, this means that $$\mu=2.985 \times 10^{24}$$ It doesn't matter what $V$ is. Looking at one of the graphs, I see that whatever $V$ is, $Q\_S$ is going to be off the charts: ![](https://i.stack.imgur.com/PVW1L.png) We're all going to die. [Answer] Yes, in fact that is one theory of how the Earth and our Moon came into being. A large body hit the earth, ripped off a section of it, the smaller section ended up in orbit around the larger. Note that gravity of the chunks will always try and pull them back into a spherical shape though, so you will end up with two smaller spherical bodies orbiting each other. You won't end up with "shattered chunks". [Answer] Given the amount of energy needed to destroy a planet, even sending another planet on an impact orbit will not do what you want (as a BTW, the impactor that smashed into Earth and created the Moon is estimated to have been the size of Mars). For the amount of energy you will need, a futuristic super weapon is the tool required. Cribbed from [another website](http://www.livescience.com/17875-destroy-earth-doomsday.html) we get the amount of energy needed: > > The gravitational binding energy of a planet of mass M and radius R is given by the formula $$E=\frac{3}{5} \frac{GM^2}{R}$$. For Earth, that works out to roughly 224,000,000,000,000,000,000,000,000,000,000 Joules. The Sun takes nearly a WEEK to output that much energy. > > > So a relativistic hyperweapon approaching the Earth at a very high fraction of the speed of light is probably the best way of going about planet "cracking", but you need to calibrate the impact rather carefully. Too "slow" and you get a ball of molten magma that gradually collapses back into a planet sized ball (or maybe a planet and one or two moons). Too "fast" and you end up with a cloud of gravel forming a new asteroid belt around the Sun. Even more energy and the pieces reach Solar escape velocity and exit the Solar System for a lengthy tour of the Galaxy. An entertaining synopsis can also be found here: <https://what-if.xkcd.com/20/> You will see according to his calculations, you need to impact the Earth at 0.9999999\*c\* to get to the effects that you are looking for, and far beyond any sort of engineering that a Type I civilization would be able to unleash on its unwary interstellar adversaries. [Answer] **No** You could not split a planet in the manner you described as several answers here pointed out. **Maybe** However, there is a special case which might result in a split body. Consider all bodies in the Solar System are split into two groups: 1) the roughly spherical ones and 2) the non-spherical ones. 1. Spherical Spherical bodies are in a state called [isostatic equilibrium](http://en.wikipedia.org/wiki/Isostasy), which is a fancy way of stating that their shape is governed by their own self-gravitation. These bodies could NOT be split by a meteor / asteroid / weapon impact. If you supply enough energy to split them, you will instead disrupt them. In the case of the Theia event, the Earth and Moon formed out of the debris produced by the disruption. 2. Non-spherical Non-spherical bodies are shaped by things in addition to their own gravitation or at least gravity isn't the biggest factor in their shape. Instead the strength of the material is sufficiently great to resist the gravity of the asteroid and maintain its non-spherical shape. If you struck a rock asteroid with enough force to cleave it and impart enough momentum, you might get the two halves of the body rotating around each other. Given some of the odd, peanut, shaped asteroids out there; it's possible this has already happened many times and we're just now learning about it. Asteroid Itokawa may have started as one of these. ![Asteroid Itokawa](https://i.stack.imgur.com/keZA5.jpg) [Answer] No, it's not possible. You can have something like Tim B's answer regarding the Theia impact but that is not a case of a planet shattering into two pieces, but rather a grazing impact where the impactor broke up but went into orbit rather than merging with the planet. (Yes, there was substantial mass exchange, but the moon is mostly impactor, the Earth is mostly Earth.) To actually split a planet is another matter--the basic problem here is that the heat of vaporization of the planet is less than the gravitational binding energy of the planet. A simple application of brute force can't break it without destroying it. Even if you have some sort of gravity generator to pull it apart without smashing it in the process you'll have the problem that the pulled-apart pieces are massive enough that they're going to turn into spheres. That will be cataclysmic for anyone on them. Not to mention that the atmosphere is more mobile than the rock, it's going to fall off the edge of the world. Everyone suffocates. [Answer] An *"advanced interstellar weapon"* would need to carefully cut the globe in half without heating past the edge, while simultaneously shoring up the exposed inside half so it doesn't pull itself back into a ball. Digging a trench allmthe way through, in and of itself, is just an engineering problem. Self-reproducing machines could dignand build more with the removed material. One could calculate the energy needed to move a half-mile wide curf out of Earth's gravity. Sealing the cut end, and building a wall to hold the air, probably involves materials stronger than what is physically possible. However, it does not have to be a ultra-thin covering. The half of the world does the job now, passively. Make an extended slab that is dome shaped but much smaller than the original half it's replacing, so it has bulk (hundreds of miles) especially towards the center. It allows for active cooling too, so it doesn't need to withstand the temperature like a passive material. That would cause the half-world to cool much more rapidly, and the gravity woukd be all messed up so even with the cap (with a lip) the oceans and air would fall towards the middle of the hemisphere, as the thin lens edges don't have enough attraction. The rocks would do likewise: even with a strong cap over the cut, it would collapse in *the other direction*. The cap needa to be made with ultradense material to provide gravity, matching the original missing half. It would be less massive than the original because it is smaller, so not 4000 miles away in places. I think you should try it with an airless world first. If you slice the moon, you could get away with hollowing it out too. ]
[Question] [ Suppose this world suddenly has night creatures that only appeared at night and disappear at day. With the world's civilization at risk of total destruction by randomly appearing night creatures, they build a floating city using the local unobtanium that allows it to float and they have it fly counter to the Earth's rotation so that it is always in the day light. What would be their considerations in designing this city such as self sufficiency, weight, aerodynamics, and dealing with constant sunlight? Assume they have modern or near future technology with the exception of floating unobtanium. Night creatures disappear and appear out of thin air but only at night rather than just shadows. [Answer] **This is not going to work.** You have to fly very fast to stay in the daylight. Over 1,000 miles per hour (1600 km per hour) at the equator. A city is anything but aerodynamic, actually it's about as aerodynamic as a brick, and will fly approximately as well. With modern tech and real life physics, you're simply not going to get one flying **at over mach one** for any sustained period. Further north or south, before getting past the arctic circle where the sun will set no matter how fast you go, the city would have to travel half as fast. Let's explore that. **Powering flight** Unfortunately, the city would have significant difficulty just to create enough power to maintain that speed. Drag increases by velocity *squared*. The [power to overcome drag](http://en.wikipedia.org/wiki/Drag_(physics)#Power), at high velocity, increases by velocity *cubed*. It's quite difficult to find any data on the cross-sectional area of a city, but I think a square kilometer is a *very* conservative guess. $$ P\_d = F\_d \* v = {1\over2}\rho v^3AC\_d $$ To fly at 800 km per hour (222 m/s), the city needs to provide 14 gigawatts in effective propulsion$^1$. That's two very large nuclear power plants running all the time if it's perfectly efficient and there is never a head wind. Of course, the city would be ripped apart by the winds before it made it a day. If anyone reading this thinks '*golly, it would be windy*' and then thinks using wind turbines to harvest the energy is pretty clever, please slap yourself. That's like generating power from a wind turbine with fans that you're powering. **Alternative** A much better idea would be to spend six months near the north pole for its summer and six months in the south pole for *its* summer. Then all you need to worry about is the flight between them every six months. Unfortunately, since the city still can't fly fast enough there will be some night time to deal with. If the unobtanium can provide variable lift and you are able to make the city airtight, you can essentially create a city space station that dives into the atmosphere occasionally to refresh air and water. But this doesn't appear to be the solution you're looking for. **Sustaining the people** As for sustaining the city, just make the floating platform large enough to grow food. Basically, if the city brings enough land with it, it can support itself. It'll still be in the weather, so it'll have rain and shine, and can even float over to better weather. There should be lots of recycling. **Weight** The weight is magically cancelled by the unobtanium. $1$: I assumed an air density of 1.225 kg/m^3 and a drag coefficient of a brick, 2.1 the same as a rectangular box. If you want the cross section of the city to be something other than a rectangular box, [refer to drag coefficients](http://en.wikipedia.org/wiki/Drag_coefficient#General). Multiply 6.66 GW by the coefficient for the shape the city will present to the wind (still assuming a 1000m^2 cross sectional area). [Answer] The answer will vary based on latitude since the earth's rotational velocity is a function a distance from the axis of rotation, e.g., 1000 mph / 1600 kph at the equator, 0 at the poles. Since the equator is the worst case, I will use that. Since mach number is temperature dependent, mach 1.3 is just an approximate reference value for your flying city. Also, not clear from your question whether you will be the only population on earth, so I will assume you are not as this adds some issues to consider. **Elevation?** High altitude means lower air pressure (reduced drag, etc.) but means you have to pressurize your city. If you needed to supply a pressure of 1/2 atmosphere, you have a static load over 1000 lbs / sq ft or about 5000 kg / sq meter. Not very high pressure for a tank, but building a pressure vessel the size of a city will have challenges. Extra complications if you want to live in a clear dome. But overall, higher is probably better in most respects. Radiation is not once of those. High elevations means you will encounter a lot more radiation. Anything over 10,000 meters is too high over a long term unless you add radiation shielding. **Air turbulence**. You will have to completely seal your city from the environment. At Mach 1.3, everything your city would be ripped to shreds by air turbulence (ripping up trees, buildings, etc.) if not encased. You need a strong container to resist not only air forces, but also deal with things like running into a flock a geese. They are low grade canonballs under your conditions. **Drag?** Does your unobtanium magically hold in in place relative to the sun, or you do have to supply the power needed to propel the city against the wind. Since you are flying a city at greater than mach 1, you will need power and lots of it (billions of watts, maybe trillions) to counteract drag. Since you exceed mach 1, there is not much you can really do about it, i.e., streamling only gets you so far because you are compressing the atmosphere to punch through it at high speed. **Cooling** your city. Remember that due to air compression, you are going to encounter high temperatures from the compressed air. You also have to get rid of the heat from generating all the power to counteract drag. So you need to run the biggest air conditioner in the world 24x7. You cannot use the ambient air to cool your city since it will heat up by around 100 C when you attempt to use it this way. **Noisy neighbor**, you will be the noisiest neighbor in existence. The sonic boom that you generate will be huge, and you will overfly each point on your flight path once per day. Nobody is going to like you. **Economic logistics**. Unless their is also a different kind of unobtanium, everything you do will cost more as the difficulty of moving everything to and from your city will be quite difficult. In fact, no jet on the planet could safely land on your city today unless you build an entirely unique airfield that brings air to rest relative to your city and still be an open air field. Perhaps if your city is large enough, your could design a leeward hanger deck that is open air large enough support the necessary air traffic. Remember that your service craft will also have to have mach flight -- unlike any existing cargo planes. **Equipment maintenance**. You will have to power your city's flight with the equivalent of fighter jet engines and a lot of them. Maintenace on such systems is very high, lots of downtime, inspection, replacement parts., etc. So you have to have lots of extra capacity, the ability to redo the parts from scratch (i.e., smelting, etc.) and trained personal pulling maintenance. **Self-sufficiency** If you are the total population you will of course have to be self sufficient. A lot like a colony on mars, except you have a few advantages, mostly freely available air and water (i.e. collect the rain, assuming you are not too high or condense it out of the air). However you will presumably need to replenish supplies for energy, etc. so the logistics statements already mentioned still apply though they would be less frequently needed **Construction**. Building all of this while under attack from your night creatures won't be a picnic either. Under the most optimistic assumptions, this city would be incredibly complicated, expensive and time consuming to construct initially. Much worse than going to the moon. **24 hour sunlight** would be way down on the list of your problems. Hang some curtains. [Answer] Honestly the tech to fly a city through the sky would probably be sufficient to simply put a city at a Lagrange point between the sun and the earth, or maybe even better, put a giant array of mirrors in space to reflect sun at the city perpetually. You would have he issue that the surface would never get a chance to cool down though. Mercury has sections that are pretty much in constant sunlight, and they can hit ~800F (430C). It would be less on the earth due to us bing farther away and having an atmosphere, but I doubt it would be comfortable. [Answer] Have a fence so people don't fall off. I'd have it hover over a sizeable ocean or just build it to float on this ocean. Are the night creatures able to swim or use tools? Building mammoth walls instead? Depends on the abilities of these creatures [Answer] Pressurize your city and go all the way up to space. The [L1 point](https://en.wikipedia.org/wiki/Lagrangian_point) is a stable orbit around the Sun, between the Sun and the Earth, where their gravities cancel each other out (beacause it's much closer to Earth). The Sun would always be "above" as far as we can say that Earth is "below". Once you're there, the energy to maintain position is just for fine-tuning. Your issues are now those of a very large space station. Plenty of material to look up. Rotate to generate artificial gravity, hydroponics, extreme recycling, etc. You might not even need the unobtanium after all, just lots and lots of resources. Today's technology could be enough. But I don't think today's resources, even if used up just for that, could lift up the mass to build a self-sustaining city of millions. More like a couple thousand. Except, perhaps, if that handy unobtanium you're not using anymore could lift stuff up to space on the cheap? ]
[Question] [ [Similar to this question](https://worldbuilding.stackexchange.com/questions/8471/would-people-be-polygamous-in-a-gender-switching-world), but with major differences. The set-up is that past-humans implemented, through biological engineering, the ability to switch between male and female in everybody. However, their society collapsed, and later humanity rebuilt civilization from the ground-up. And retained the ability to switch sex. The switch takes place over a period of approximately 6 months, and is reversible at any point. You need to want to switch, though you don't need to think about it all the time -- a subconscious desire will work as well. You can get pregnant in the female form, and switch back in the early stages of the pregnancy, which "suspends" the fetus's growth. If you're in the late stages, however, you can't switch back until you give birth. It's also possible to stop the switch part-way through, if you want, which will leave you with hermaphroditic features. So what would be different this time around? [Answer] Society has long relied on the role differences between genders. How useful are they? 100% of societies have them, with only a scant few new cultures (like ours) trying to see what happens as we break them down. Why are they useful? Consider what happens when you ask a 5 year old what they want to be when they grow up. The answer is usually something like "an astronaut" or "a firefighter." That answer will change over time, so its not really worth giving a 5 year old astronaut training (other than that, perhaps, its fun as all heck for the 5 year old!) Now, consider a role which benefits from lifelong training. A culture which begins training at 7 is fundamentally 7 years behind a culture that trains at birth in such a role. Now consider if there are diametrically opposed roles, where it is terribly hard to be good at both. There would be an advantage to artificially dividing the culture in half and giving each half training from birth. Societies have shown that, with the presence of biological sex, that division is incredibly beneficial in a remarkable number of situations. Only recently have we explored whether giving individuals more choice and less sex-driven roles is beneficial for society or not (and the experiment is still running!). So, in your case with a fluid biological sex, the answer is less obvious. It could be that this results in a society with fewer roles being forced on us, and more choice for individuals. This is the utopia side of things. It's also possible that it is *tremendously* difficult to keep up without such a split of roles, and society crumbles under it (the distopia side of things). More likely, however, society would not crumble. Society dislikes doing things like that. More likely, if it *needed* a division of roles from birth to succeed, it would develop a new method of division. Perhaps birth gender might be tatooed on you. Or perhaps society would divide on hair color. Or perhaps a powerful caste system world form that divides the world into two castes that always intermarry. *This is what I find incredibly exciting about the recent shifts in women's roles. We, as a society, actually have absolutely no clue what the result will be. All we can do is go down a path, and see what the answer is. Hopefully we can go at a pace which allows us to retain balance as we go!* [Answer] Sexism as we know it would disappear. No more "woman in the kitchen" stereotyping; no more "man at work". Since people would have the opportunity to experience how both sexes work and operate internally, there would be greater understanding between people. To put more bluntly: women would understand being kicked in the nuts, and men would understand bleeding from your nether regions every month. I'm going to go out on a limb and say there may also be a fairly significant number less suicides. Since sexuality-related discrimination would be far rarer, teenagers especially would feel they don't need to conform as much, and thus if they can't they wouldn't feel pressured into ending their own existence. However, this would, as bowlturner says, open up the market for "selective employment" based on physical qualities. Since men are generally stronger, construction companies might choose to only employ men; if a woman wants to work in construction she can change herself to a man. [Answer] Interesting question. I would say most of our issues about sex and gender inequality would be gone. At least our current issues. I'm sure we would find other ways to discriminate against each other. I would expect that more people would want to actually bare their own child, at least once, which would make 'fatherhood' a very different issue. This would likely put any custody cases back to the 'mother' by default unless she proves to be unfit. Since anyone can honestly 'choose' which gender to be, I would expect some jobs would truly become sexist, 'only men can apply for this...' only women can apply for that... and if you want one of those jobs, you will make the effort to change. This also make me wonder about the sex of a child until puberty, I'm guess they have no sex organs, and will develop them later in life? What kind of teenagers would we have? now they are hormonal bundles, but each side gets a different cocktail of chemicals. What would happen, here? is there a default sex? Female? or each person leans one way or another? Or do they fluctuate back and forth in the 'hermaphrodite stage until settling in one direction or the other? Because much of our sexual identity starts here. [Answer] Ursula Le Guin (who else) has written a book which involved just this thought experiment: <http://en.wikipedia.org/wiki/The_Left_Hand_of_Darkness> Highly recommended reading. It's especially interesting because of how it also explores how gendered humans (or at least one particular man) would act and feel in such a society. [Answer] First, the problem with restricting jobs to men only or to women only would vanish, because anyone who wanted such a job could simply switch. We currently condemn such discrimination because it keeps people in the unemployment line, but with the ability to switch sex, only those who refuse to make the choice are kept out of any particular job. There would also be the turmoil of people who want to switch, but are in a relationship (whether marital or parental) with people who want them to remain as they are. If you're a man who prefers women, or a woman who prefers men, you won't want your spouse to switch without a very good reason. [Answer] A considerable proportion of the population would be male, for the most part, only becoming female if they have need of it. Being female habitually rather than male would mean that you'd have to experience periods, less muscle growth and strength, etc. Prejudices would no longer be about what your sex was, but if you had some kind of defect that didn't allow you to change it. Abortion rates would decline, because women who decided they weren't ready for a baby would be able to become male until they decided they were. Certain sports it would be habitual to transition from one sex to the other while playing, new games and sports would come about that require you to transition while playing, as a handicap, to show that you're on the other team, etc. ]