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[Question] [ I want to make a world similar to ours, with one additional feature: Time travel. There is no difference to me if its loop-based or infinite universe based. But there is a catch: The theory of relativity has not been disproven, disallowing faster-than-light travel. Is there any viable way to do this that's consistent with modern science (no matter how unlikely, say quantum stuff)? I'm talking both-way time travel here, both past and future. [Answer] General Relativity does not disallow time travel nor does it disallow travel to the stars in times quicker than light can get there. Both theories are "local" theories and their symmetries only apply locally. That may sound simple, but it's a fairly technical statement. Basically, the prohibition on FTL relative velocities applies only at each point in space: At a given point in space, no two objects can have a relative velocity exceeding that of light. But in the currently accepted theory of cosmology -- which is 100%-compliant with Relativity -- there are galaxies receding from Earth at speeds greater than that of light due to the expansion of the universe. There are several ways to time travel allowed by Relativity, none of them easy. First, there's the [Tipler Cylinder](https://en.wikipedia.org/wiki/Tipler_cylinder). Construct an very long, very massive cylinder and spin it so that the surface speed is near the speed of light. General Relativity says that there will be paths that can be followed near to the spinning surface which (among other things) travel backwards in time. (The construction of infinitely long cylinders that hold together when spun up to light speed, the source of energy to spin it up, and the construction of space ships which can fly near it are left as an exercise for the reader...) Second, there are wormholes. Create a stable wormhole pair (again, left as an exercise for the reader). Take one of the pair and put it in a relativistic spaceship (LaaEftR) and fly off to the stars and back (LaaEftR) so that that the people on the ship have experienced ten years less time passing than those on Earth. The two end of the wormhole pair are now a time machine that allows you to go through it (LaaEftR) ten years into the future or ten years into the past. There are lots of similar constructs permitted by General Relativity: spacial tubes, the [Alcubierre Drive](https://en.wikipedia.org/wiki/Alcubierre_drive), etc. It's noteworthy that all of them share one characteristic: We have no idea at all how to actually build one. They invariably require material of outrageous strength, outrageous properties ("[exotic matter](https://en.wikipedia.org/wiki/Exotic_matter)"), or outrageous amounts of energy (usually all three). It's not that it's an engineering challenge to build them, but we can't even begin to suggest how to do it -- it's completely outside any plausible extrapolation of current technology. Other that that, no prob! [Answer] If time travel does exist the only thing I can think of that would prevent it being used for FTL is an application of Causality Paradox such that attempts to use time travel for the express purpose of FTL would fail. There are two failure modes: 1. Outright failures, time travel is impossible when you're trying for FTL. 2. Failure in Detail, detail failure is different and more fun; you can travel back in time with the intention of defying the laws of nature with an FTL transit but you can't actually succeed. No matter what you try there is always some form of roadblock, accident, or detour that prevents you from arriving any sooner than you would travelling by less esoteric means. I suspect there is a cool science-y sounding explanation for why that might be, maybe something involving "inviolate temporal reference points" I don't know. Do note that this allows for accidental FTL travel in the course of temporal sight seeing which could be useful to the storyteller and potentially disastrous to the traveler. By the way I love this question; normally it's "how do I have FTL without Time Travel?" which is easy, and a little irritating, since the Arrow of Time seemingly prevents Time Travel anyway and FTL based Time Travel models assume a shifting reference frame which as far as we can determine is impossible to create due to macro-process temporal asymmetry (entropy). This is much more challenging and interesting. ]
[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/102913/edit) Most people would like to have a choice in who leads their country, and so many people are more attracted to democracies. Dividing out the power to govern among many people who the voters see as the most fit for the job also seems like a better idea than bestowing all or a great amount of it in one individual, who may not even be a good leader for this country even if they do have royal blood. So, in a modern world where most countries would likely to be democracies, why might one country that has already established as a democracy in the Western world want to switch to a monarchy instead? What kind of situations might this happen in and are there any instances of this in real life? I'd prefer non-violent, gradual reasons, but if there must be some kind of revolt or violent seizing of power, I'll make do. The monarchy would also preferably stay in place for a long amount of time, so the king/queen wouldn't be overthrown within a couple of months after taking their throne. [Answer] Ultimately, even democracies need a good old-fashioned dictator from time to time to get things done. This is in essence the rationale behind the declarations of State of Emergency by certain governments; what they're saying is that while the emergency is happening, voting is suspended, the constitution is suspended, and everyone has to do what the leader says. In practice in most democracies, this is used to marshal responses to cyclones (or typhoons, hurricanes or tornadoes depending on your region), tsunamis, volcano eruptions or other natural disasters. Generally, nothing is really done that would violate the constitution anyway, and when all is back under control the state of emergency is lifted. That said, many of the countries affected by the 'Arab Spring' had States of Emergency in force for around 30 years, with the leaders clinging to power via that method. So, it can be abused. Imagine a nation where they're faced with constant threats; war, famine, natural disaster. Maslow's Hierarchy of Needs dictates that the populace just want to survive. Their sense of significance (represented by their ability to vote) is no longer as important to them as that sense of security they get from a competent government managing armies, food supplies, disaster relief, etc. In such a case, a long term benevolent leader who has proven to be fair and competent in distribution of vital supplies, dealing with insurgents, etc. may be seen as a viable 'permanent' alternative to constantly having to vote for someone who says one thing to get voted in and then always does something else. Reliability and trust comes into play here and it may well be that electing someone like our 'hero' on a permanent basis means the populace can focus on the day to day of their lives, and leave the strategic planning with someone they can trust. What history has taught us though is that the competence of the father is not always visited upon the son. (Not saying this selection should be along gender lines, this is just a figure of speech.) In that sense, I suspect that instead of a traditional hereditary monarchy, you'd have a council select a new leader for a lifetime appointment upon the death of the last king or queen. Kind of like a supreme court judge appointment in the USA; selection based on competency and the council then reverts back to executing the orders of the new monarch and in time sets about succession planning when the time is appropriate. [Answer] I'm going to stay on the idea of "want", reasons a country might "want" monarchy rather than democracy. 1) Cult of personality. Someone with a celebrity or even god-like status or whose recent heroic acts saved or altered the country. Such a person could be swept into power on the shoulders of the masses, even bypassing elections. Moreover, if the person has bloodties to an early monarchy it could be argued as righting an old wrong. 2) Failure unique to democracy or seen to be unique to democracy. a) corruption ie a supposedly democratic system in which voting is rigged, positions are sold, etc. b) gerrymandering ie some votes are rendered null due to complicated rules such as regional districting with tricky maps. c) disproportionate representation: democracy is still majority rule. If the majority is of a caste, class or ethnicity divided from or hostile to the minorities, a single charismatic ruler might be seen to unite them all. 3) Marriage as both a how and why. Uniting the Republic with a Kingdom and accepting the rule of the Monarchs. There would need to be a compelling reason (technological, magical, financial advances) to make this appealing or necessary. Unless it were done by conquest: "Hi, we're your Kings. Parliament is disbanded." 4) Religion or prophecy. A belief of the people that is older and stronger than the rule of law or voting. A prophecy can be exploited to undermine political rivals or avert a catastrophe such as civil war or Brexit. 5) Magic. A person with powers, technology or allies powerful enough for them to ascend/create the throne. 6) War. Civil war in which one side declares a monarchy. War treaty in which the country is given away to one of the victors or forced to accept treaty conditions as part of its surrender. Annexed. 7) Coup. An elected executive official who disbands other branches of government or voting for an indefinite period. Or who is catapulted into leadership through the plot of the military or intelligencia. [Answer] History offers some examples. Germany elected Hitler because he promised to restore Germany as an economic power. He became the Fuhrer (chief) and kaiser (Caesar / emperor) once his National Socialist Workers party held a majority. Had he not over reached into Russia, we might be seeing the third generation of the Hitler dynasty today. The Baath party in Iraq was elected, Saddam, the hired muscle (equivalent to the paid rioters in US politics), became a monarch by walking into the elected president's office one day and saying "get out of my office". Had his counter intelligence operation of exaggerating the country's progress with nuclear and biological weapons capabilities not backfired, he might still be in power today, or retiring and turning power over to his sons. On a more hypothetical note, in times of crisis it may be more desirable to have continuity of leadership than regular elections. If the leader is well liked and competent, and his/her offspring are equally so, I can see that evolving into a monarchy. In the USA, there is a tradition that presidents can serve no more than two terms, but other countries have no such rules. In Canada, Trudeau 1 governed 15 years for example. See @timb s answer for a better explanation. ]
[Question] [ This question asks for hard science. All answers to this question should be backed up by equations, empirical evidence, scientific papers, other citations, etc. Answers that do not satisfy this requirement might be removed. See [the tag description](/tags/hard-science/info) for more information. In a very distant future people have survived by slowing the metabolism to extremely long timescales, reducing the energy consumption per time. It is causing thought processes and movements to be exceptionally slow. A normal "5 minute conversation" would then take longer than the current age of the universe, even though it would still "feel" like 5 minutes for the people conversing. However on the microscopic level proton decay is a significant problem, being the number one reason for death. The particles of which we are made of, are decaying. How could this very advanced civilization survive proton decay? [Answer] Um. Proton decay is not your biggest problem- instead it's something like [the half-life of DNA](https://en.wikipedia.org/wiki/Ancient_DNA). According to this article in Nature, this is currently something like 521 years- so before a single cell has had time to replicate, all of its DNA [has literally fallen apart](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3497090/) into monomeric units of nucleic acids. Honestly, you'd probably have bigger problems even before you hit DNA degradation. All biological processes have much shorter half-lives than isotopes, so if you slow down metabolism and prevent the cells from actively replacing things that have a tendency to fall apart. In an awesome paper named "[Microtubule Catastrophe and Rescue](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3556214/)", the authors discuss how the fundamental skeletal structure of the cell is in a state of dynamic instability- they're constantly being destroyed by random processes in the cell and it's all the body can do to build them up just as quickly. Without a constant supply of energy that can rebuild things, organisms kinda just... [dissolve](https://www.youtube.com/watch?v=zfZVXl3LGds) (warning - kinda graphic video). That goes for DNA, enzymes, proteins, and pretty much every other structure that's created by a non-spontaneous process. ]
[Question] [ I am busy drawing a fictional map of a city. It has all the technology, economics and sociology of the real world. The city has no nightclubs, very few restaurants, no bars: very few places to publicly socialize. Each suburb gets a corner grocer, religious facility, a library and a theater. Police, medical and fire-protection are spread across several suburbs. I have taken a personality test and it came out as [INTJ](https://www.wikiwand.com/en/INTJ). This makes me an introvert. Introverts get exhausted by social interaction and prefer time alone. Extroverts are energized by social interaction, hence they make use of social clubs. Digging further into personality theory, in the real world, the extroverts outnumber the introverts 3:1. How different would a world be if the ratio was the other way around? If we had more introverts than extroverts. How would the 'community' or 'public' spaces (libraries, theaters, bars, parks, etc) be used? What are the other considerations in my introverted community? [Answer] What is introversion People tend to misinterpret introversion as either social awkwardness/anxiety or complete lack of desire to socialise. [Neither is true even for highly introverted people](https://www.wikiwand.com/en/Extraversion_and_introversion#/Introversion). Oversimplified, introverts invest into quality of a social interaction and do not care about quantity, while extraverts do the opposite. While introverts often deliberately avoid socialisation especially in crowded settings, [they can be more empathic and interpersonally connected than extraverts](https://www.psychologytoday.com/basics/introversion). The latter stems from introverts' preference for *deep relationships based on trust, in which they invest heavily (emotionally and physically). Instead of having hundreds of acquaintances they barely know, they opt for having fewer but closer and more reliable friends. Does it mean that introverts do not go to the bars, restaurants, or nightclubs? Of course, no! Those are more about the socialising preferences rather than introversion-extraversion. Granted, introverts might be less inclined to go to such places on a daily basis. However, a bar with a nice quiet corner at the back could be a perfect place for an introvert to enjoy their thoughts or to observe extraverts participating in their shallow social interactions. Society of introverts* A 3:1 introversion to extroversion ratio in population would result in dramatic changes in society. Many developed societies of today praise extraversion and heavily promote it from school to business environments. Think about all the group work students are forced to do in schools, projects and teams in business, negative stereotypes about quiet personalities, and so on. [The US society is probably the most archetypal example of this extraversion bias](https://www.scientificamerican.com/article/the-power-of-introverts/). Unfortunately, it puts introverts who perform the best alone at disadvantage. Your society will be less oriented toward group work, networking, and self-promotion. More time and resources will be spent on actual work (at least I hope so). It is likely that the society will be more meritocratic since introverts tend to spend more time before making decisions and are less subject to peer pressure. It is also possible that people and workers will be heard more since introverted leaders [tend to listen to their subordinates more](https://www.forbes.com/2009/11/30/introverts-good-leaders-leadership-managing-personality.html). It is important to note that introversion does not necessarily lead to individualistic mindset. Your society can be perfectly collectivistic and still comprise the majority of introverts. It only means that they will put the interests of the community before their own. The abundance of introverts also does not mean a society of 'lone wolves' secluded each in their respective den. But it will most likely mean less flashy culture and fewer people intruding in lives of others. Cooperation will also exist but probably with less drama. But I would not expect power struggles to disappear. They will just tone down and become less dependent on who-knows-who. Back to public spaces As it was mentioned in comments and other answers, introversion-extraversion is a continuum and a person can be anywhere in-between. Pure introverts are as rare as pure extraverts. Even pure introverts could use entertainment facilities once in a while. The rest of the population will be visiting those even more often. You might want not to completely eliminate your bars, clubs, restaurants, and similar establishments but to think how to adjust them to suit introverts. A bar with dimmer lights, somewhat isolated booths, and not so loud music could be a good place. A nightclub could have a second floor where guests could relax and spend some time alone or with a small company of friends without all the noise and sweat of the party downstairs. I do not think that restaurants will be affected much since they are about food. However, the celebrity chefs might become less of a thing. The celebrity thing itself might never be a thing in your society, for that matter... [Answer] I am going to assume you are referring to a human, not alien, society. Human societies are extremely diverse. One glaring example is the urban-rural divide. This divide alters the opportunities for social interaction. Isolated sparsely populated rural communities have very few institutions that allow for social interaction, beyond religious centers and the local store. The economics does not support large social venues. Thus, people in isolated rural communities would live the lifestyle of your introvert society. On the other hand, densely populated cities force people to closely interact and to come together in large groups. Consider just the educational system - single-room schools vs hundreds, if not thousands, of students. There are also clear distinctions between people living in densely populated apartment buildings vs suburbia. Research indicates that suburban neighbors are much more interactive with each other than are inhabitants of high rises. High rise living tends to produce introverted behavioral interactions (compare how people interact in elevators vs how they interact over the back-yard fence). There are anecdotes about people meeting in bars who have lived in the same building for years, but never interacted. There are cultural differences, as well. Japan, for instance, puts a high premium on privacy, in spite of a densely packed population. Japanese culture has developed the ability to be alone in a crowded room. Boundaries become very important, and violating these boundaries is heavily socially sanctioned. One can be in a very crowded train, and still be alone. Isolation pods at airports are common in Japan, and catching on elsewhere. See [Italy's ultra-cheap airport 'capsule hotel' lets you sleep in a pod while you wait for your plane](http://nordic.businessinsider.com/photos-of-benbo-italy-capsule-hotel-2017-5/) for an example. So how many of the differences between introverts and extroverts are the result of a genetic vs an environmental/cultural determination? How much of human behavior and attitude is driven because the people are living in cities, vs how much influence does living in a city have on human behavior? However, high-functioning autism IS a genetic characteristic. There are notable differences in how autistic people respond in social situations. They, in point of fact, do require periods of quiet time. It is not so much a distinction on a generalized introvert-extrovert trait, but on a very specific wiring of the brain related to the perception of social situations and social cues. Thus, the answer is not conjectural, but observable. If the ratio of autistics to neurotypicals was reversed, and autistics became the norm, there would be radical social changes on society. Perhaps this is more specific to your question, so I posit your answer can be found by regarding the preferred environment of the high functioning autistic. It would be synonymous with your introvert-extrovert division, but would be neurologically supported. So, perhaps looking at a well-defined and studied group - those with Asperger's - would be a good starting point to answer your question based on sound medical and psychological science. I would suggest that entertainment venues would be the most radically effected, as they tend to be voluntary activities. That is, there is no compelling reason to attend entertainment institutions. We have already seen the demise of the movie theater, as private and personal media has become common. People are curling up in front of large screen televisions with surround sound, leaving movie theaters to a particular dwindling segment of the population. Virtual reality is, by definition, isolationist in nature. The participant is locking out the real world. Autistics prefer such personal entertainment venues, rather than more public venues. Public venues that provide strong privacy boundaries, such as seating in a public environment where the seats are distinctly separated, might survive. It is also my experience that huge sports venues would be poorly attended. The crowding on entering and exiting would be the main impediment, as are the line-ups for food. If the seats were individual, with arm rests, as opposed to bench seating, perhaps. But even these types of seats produce discomfort in autistics. On-line shopping is another trend that would become common. This societal change, especially over the busy Christmas season, is well suited for the autistic. I suggest that there would be few bricks-and-mortar stores in your community. Modern technology would enhance the formation of such a community. In fact, one could posit that our modern technological society is tending to such a non-social environment. But social interactions would not cease entirely. They would change in nature, but they would still exist. Interactions would be far more personal, and based on specific tasks, less based on the necessities for social niceties and talking just for the sake of talking. Saying 'hello' would be done as a means to announce your presence, rather than any social convenience or requirement. The traditional initial 'How are you?' greeting would simply vanish, as being purely superfluous speech, as opposed to task-specific communications. Facebook and twitter would become less social media, and more information dispersal media. Edit In researching a biological basis for introversion, I came across the following article. [Will the Real Introverts Please Stand Up?](https://blogs.scientificamerican.com/beautiful-minds/will-the-real-introverts-please-stand-up/). It posits, towards the end, in the section titled > > The Engine Behind Extraversion-Introversion > > > that variations in dopamine response may be a biological determinant of introversion. > > This probably explains why a lot of introverts notice that they often > need to be alone to recharge their batteries after vigorous social > interactions, whereas extraverts appear to gain energy from social > interactions. This can be explained by dopamine's function in > energizing potentially rewarding social interactions, as well as its > role in overcoming the cost of effort. For introvert's, such > interactions are more effortful and tiring due to their less active > reward system [5]. > > > However, the article also emphasizes that actually identifying what constitutes introversion is extremely controversial, with a wide variety of interpretations. There are 'check lists' galore that are applied, some completely contradictory. So I posit that unless and until the determination of what is called 'introversion' has some biological basis, such as autism or dopamine response, instead of a vague 'personality' or 'behavioral' basis, trying to define an introverted society will be like nailing jelly to a tree. [Answer] If the ratio of socially awkward to average 'introverts' remained unchanged from our world, then there would be little expected deviation from ours. Introversion-extroversion is a scale, not this or that. Introversion (along with other factors) produces the need to have time away from people. Extroversion (along with other factors) produces the need to spend time with people. A number of factors can temporarily change one's placement on the scale, such as depression producing introverted needs, and a surge of confidence raising extroverted needs. Some people entirely 'flip the scale' in the course of a few months. An example of this happening is the common high school/college transformation. A popular HS student buckles down on his studies in college. His social need may drop after a short/long transition period of anxiety about "never having time to do anything anymore." A quiet girl re-invents herself over the summer, after vowing to herself to "stop being a wallflower." Her social need may rise after a short/long transition period of anxiety, feeling overwhelmed by the sudden surge of social interactions. What does this mean for your world? Well, if we are to presume that it is a true flip, everyone's true intro-extra placement being reversed, then most people would still have both qualities. This means all intro and extro activities appealing to IRL population would still be appealing in yours. There would likely be less social clubs and amusement parks, off the top of my head, but those that exist would be every bit as profitable as they are in ours. Intro-leaners enjoy these activities, but desire them less frequently than extro-leaners, and extros would still be present. I also suspect your world would favor 'Netflix and chill' (but not Netflix, for legal reasons) over nights out as the 'norm' - more quickly than is happening in our world. (Most people of any scale placement pursue romantic partners/intercourse.) This might actually lead to the hook up culture happening more quickly and intensely, contrary to what ill-informed people believe about introversion. But I digress. In summary, I would suggest researching the scale a bit more. Wikipedia would be a good place to start. When you are then (and only then) ready to worldbuild, focus on what changes would be produced by a Lower drive for social encounters, not a fundamental change to who people are. Intro-extro scale does not affect which activities someone would or would not enjoy, only how frequently such activities would be desired. [Answer] A city dominated by introverts would be based on a society/culture that favored service over social offerings. A benefit of living within a civilization is that many services can be provided. You don't have to forage your own food, find your own fuel. Technology is provided to you which you didn't have to build or invent yourself, etc. I believe that many introverts live within society for these reasons, they simply want society to provide them with services and technology, not social interactions, for the most part at least. A society of introverts would be all business, blunt, and everyday life would be straight to the point. ]
[Question] [ These planets would be similar in size to Earth. Mars and Venus don't need to exist in this scenario. So how many Earth-like worlds can be squeezed into the sun's "goldilocks" zone? Mars and Venus like worlds can be ignored. [Answer] Having more than one planet in goldilocks zone is surely possible, after all our (real) Venus is just outside it and Mars is within. Having more on very similar orbits is more complex due to possibly disruptive interactions between planets. This may be easily overcome having several planets on the same orbit in L4/L5, the so called "Trojan" positions. These positions are very stable. You can easily have two "trains" of planets well within the habitable zone. [Answer] It is all about stability. [Kolmogorov–Arnold–Moser theorem](https://en.wikipedia.org/wiki/Kolmogorov%E2%80%93Arnold%E2%80%93Moser_theorem) says that Solar system is mostly stable. Mostly is the key word. Even with current settings, if we run thousands billions year long simulation we will see some orbit instability([mostly it would be Mercury](https://en.wikipedia.org/wiki/Stability_of_the_Solar_System#Laskar_.26_Gastineau)). The closer you pack you planets, the worse it would be. You can put hundreds of planets there but in several years their orbits would deteriorate. I met a rule of thumb that distance between planets should be about [10 Hill sphere](https://en.wikipedia.org/wiki/Hill_sphere) radius for long term stability(billions of years). If we assume Goldilock's zone size = 0.5 au then for Earth sized planets that would be 8-9 planets. Obviously that's quite unlikely to happen naturally. Decision with putting a giant, and placing Earth sized planets in it's Lagrangian point would be less effective because giant planet has pretty big Hill sphere. [Answer] Probably not. In our solar system the planets are on an exponentially increasing set of distances. (See Titus Bode Rule; Dermott's law) seems to show that orbital bodies are spread out in a power law. Note that TB is now considered a coincidence. (I'm skeptical. 3 items is a coincidence. 6 is a not understood phenomenon.) That said closely space planets will have similar periods, and will be near each other for relatively extended periods of time. This allow for fairly large perturbations. I suspect that there is some minimum ratio of orbital period to have long term stability. Earth is just barely inside the zone, and if not for the greenhouse effect would likely be an ice ball (18 C colder) It may be possible if you have a gas giant acting as a shepherd to keep orbits stable. Or maybe that would be more disruptive. You can get 2 planets by having them as a binary, tidally locked together. You could have a massive planet in orbit, then a series of moons that were individually habitable. This puts them still in an exponential series from the massive planet but effectively at the same distance from the sun. [Answer] Imagine a planet sharing exactly the same orbit with the Earth with 180 degree angular difference i.e. it is placed at the other side of the Sun. Then it looks impossible to detect such a planet at a glance. However, if such a planet really exists, then it is expected to change the calculated orbits of the space probes sent to Mars due to its gravity but no such anomaly is obsreved. Then the answer to the question is, almost 100%, no, unless it is really really a small body. ]
[Question] [ This question is a thought expansion on this [What early tools might be devised on a planet where diamonds were abundant?](https://worldbuilding.stackexchange.com/questions/89024/what-early-tools-might-be-devised-on-a-planet-where-diamonds-were-abundant) According to [this article](https://www.azom.com/article.aspx?ArticleID=6101), prehistoric men already utilized gold and silver for decorations and bullion for trade (or currency), and learned that harder metal, named iron and copper, is better used for tools. However, what if silver rarity is swapped with iron and gold with copper? [![Element composition](https://i.stack.imgur.com/Jpg0km.gif)](https://i.stack.imgur.com/Jpg0km.gif) As you can see from the earth's element chart, iron is abundant enough to be included in the chart (5%), but in this world it's silver that is abundant. Will the prehistoric man be able to utilize gold and silver, and how? Every other metal rarity is unchanged. I'm mainly concerned that gold will not be used tools, and whether iron will be the new gold instead. [Answer] If gold would have been abundant we would have used it instead of lead, not iron, because it's not hard enough and would make very poor tools, while it could be durable plumbing and "silverware" (with less lead poisoning). Silver is much better than gold for tools, but it's nowhere near iron; it could have replaced bronze and brass. Silver is also a very good conductor (electrical and thermal) and could replace copper (for most usages it would be much better). I am not aware of silver or gold alloys with useful mechanical characteristics (i.e.: that could replace iron alloys). [Answer] The answer is simple, metallurgy. Prehistoric man was making alloys of all sorts. There are [numerous silver alloys](http://riograndeblog.com/metal-hardness-how-to-measure-it-and-why-it-matters-for-silver-alloys/) which offered hardness in the range of iron or even some steel! One of the best is an alloy of silver and copper, basically what Sterling silver usually contains. Even though copper is in short supply, fear not, you need less than 8% of it by volume. Other alloys exist which are even harder. Also, you of course would want to cold forge the alloy for even extra hardness (or not if shattering is an issue). These weapons would hold an edge fairly well, and could be used for many different applications (tools, armor, etc) where steel is usually used. An interesting point though would be that he who wields the great iron sword of scarcity would be at a great advantage when fighting those with the mere commoners silver swords... [Answer] Gold is very soft, so it is not so good replacement for hard metals. Could be used for mirrors and such. In fact, if you were to cover buildings with gold, the light would be reflected to a great deal so it might make the building cooler in a hot climate. Silver has a very pleasant side effect of killing bacteria and fungus. If it was common to cook food in silver containers, use silver utensils, silver door knobs, etc, then you may have much fewer diseases spreading in your society. Silver is also fairly hard so could be used kind of like iron I guess. I should say that copper is also somewhat bactericidal and containers from brass are known to be healthy to use due to small leakage of copper into the water/contents, but copper is far less effective than silver. [Answer] some alloy of bronze would replace most of what we do with iron. gold and silver are much heavier than iron, so even without the softness, making tools from them would greatly effect what types of tools people would make with them. ]
[Question] [ Some background on this question, I was trying to construct an international organisation whose main job is to patrol, investigate and protect its member countries from anomalous threats that have been regularly popping up. These threats can range from a simple humanoid abomination terrorizing a handful of people to an enormous eldritch abomination who could destroy entire cities. My initial reasoning for it being an international organisation instead of just the individual countries enacting their own organisation is because some of these anomalies are capable of organizing themselves into a multinational threat which might necessitate cooperation between numerous countries within the region. However I wonder if this could be rendered redundant by any simple changes within an existing government organisation or by simple cooperation between different government organisation. So I ask you this is there any specific conditions that would necessitate an international organisation to form that patrols its member countries and cause them to work together in order to handle the occurrence of anomalous events? [Answer] If you make a SECRET international organization, it would be far easier than having the backing of multiple countries. It would be a lot of red tape, many years, and quite a few arguments to get something like that off the ground. Even if it was successful there would likely still be different restrictions in each country. Likely couldn't get all of the countries in on it either, but that's good conflict. If the scope of your story allows for years to be there for negotiations to complete then you're set. They could be sped along by the gravity of the threat, but at the same time, you have to consider how capable this team is. Is it a team that was previously working in the shadows and can come out in an instant and say 'hey, give us permission and we can help' or will it be people who were previously ignorant rushing to garner control of the situation. The former lends your group more power in the situation, the latter and a great number of politicians would likely fight against the change. Essentially: What can these people do that my police can't? You'll have to remember that it's not just policy that would be at odds in a situation like this as well, but public opinion. A politician might know something is the right or smart thing to do, but if their entire country is against working with X, Y, or Z they could still be swayed otherwise. Worldwide agreements are complicated beasts without the proper motivation to fix them and fast. Your MOST LIKELY scenario would be individual groups in each country along with an overarching group that helps them communicate and mobilize across the globe. That way, each country gets to do things their way, but when the danger crosses borders there are people available who can quickly and effectively navigate the red tape as well as assist with problems such as language, culture, and travel. It would still be a balancing act. As simply as possible, each country would have to feel in control and simply gaining positive support by being a part of this network. If they feel manipulated or controlled tensions would most likely rise up again. [Answer] Excerpted from the [Constitution of the WHO](http://www.who.int/about/mission/en/) (World Health Organization). > > * The health of all peoples is fundamental to the attainment of peace and security and is dependent on the fullest co-operation of individuals and States. > * The achievement of any State in the promotion and protection of health is of value to all. > * Unequal development in different countries in the promotion of health and control of diseases, especially communicable disease, is a > common danger. > > > The rationale for the WHO is the same as the rationale for your organization. A paranormal threat might establish itself and strengthen in a region of the world where the financial and institutional resources to combat it do not exist. As stated, these circumstances pose\ a "common danger" to all the peoples of the world. Your organization can be an arm of the WHO. It may or may not want to proclaim itself as an arm dedicated to fighting paranormal threats, depending on how up front about the existence of these threats the powers are in your world. WHO is great cover. It is already an international organization and already tasked with going to remote corners of the world to keep humanity safe, and for decades has been recognized by foreign governments as an entity dedicated to that task. Also the WHO already has a sweet and swanky headquarters in Geneva. This proposed expansion can house your paranormal defense branch. [![enter image description here](https://i.stack.imgur.com/cKj3z.jpg)](https://i.stack.imgur.com/cKj3z.jpg) from [archdaily.com](http://www.archdaily.com/770287/paolo-venturella-proposes-plus-is-more-for-who-headquarters-extension/55a59cbbe58ece562e000068-paolo-venturella-proposes-plus-is-more-for-who-headquarters-extension-image) That is me in the foreground in case you were wondering. [Answer] Well, [INTERPOL](https://en.wikipedia.org/wiki/Interpol) is a normal world (non paranormal) "intergovernmental organization facilitating international police cooperation". You could borrow from it its primary premise and adjust to paranormal affairs. Looks credible to me. Indeed, there was some thing similar by the middle ages controlled by Roman Church. They had a handbook/manual you can find today: [Malleus Maleficarum](https://en.wikipedia.org/wiki/Malleus_Maleficarum). ]
[Question] [ What would be the daily calorie requirements of a flying creature that could carry 200 lbs on its back? Are there features that could make a significant difference in this calculation (cold blooded/warm blooded, mammalian vs reptile, marsupial vs egg laying ect)? (If evidence is brought that supports a significant difference in calories needs based on this I will clarify my question.) In nature I think the wyvern would only fly to hunt for food, to find mates, and to look for new nesting grounds. Though domesticated ones would have a more aggreesive flight schedule and need more food. As for how high/far/fast, pick options that tend towards lower calorie requirements. Evolutionarily speaking, lower calorie requirements makes it easier for the animal to survive (unless it's too slow to catch prey). I'll include that the planet is currently earth. Azuaron's answer may end up being the best. I chose 200 lbs because I knew it was at the very extreme end of what could be possible, if it even was. [Answer] So I did some math by comparing beasts of burden to flying critters and their caloric intake and requirements. A Bald eagle will consume about 1 pound of food a day with an estimated calories of 832. This number is likely small but is the best I could find online. A Bald eagle weighs about 3 kg. A horse doing moderate work is recommended to have a daily intake of 25000 calories. To carry a person weight, assumed 100 kg, the horse needs to be at least 500 kgs. This is our best bet on how much a wyvern would have to weigh at minimum to carry a human rider for any amount of distance. taking into account their calories per kg ratios and applying the ratio of the eagle to that of the horse ends up with requiring 138,000 calories a day to carry around a rider on their back. Now this is assuming that they have a metabolism similar to that of a birds which as non-birds is probably inaccurate but that number can give us an estimate on how much they might need. Also this number is likely most accurate for a wyvern in nature. This means that the creature would need a much larger likely half again as large of a diet to be healthy. Also this number is likely on the low side in ways that I can't account for but guess would mean upwards of an additional 20-50% more calories due to caloric intake not being a linear in relation to mass. This brings us to a total of 312000 calories a day. Or in more easy to digest terms 320ish pounds of 85% lean ground beef a day per wyvern. [Answer] I would start with a logarithmic Average, I know that Humming Birds have rather high intakes, insanely high actually, I'm rather surprised they survive as a species honestly, whereas a horse, we know what it takes to fire that hefty hunk of muscles I'm fairly sure, keep in mind, I don't actually have any of these exact numbers on me, I'm simply offering ideas to at least attempt to give you a coherent answer using the knowledge which I am familiar with. There's also Elephants, Whales, Wildcats, and any other Large Creatures that you can get the intake Data on, remember to regulate your Weight values, some might give you kg whilst others give you g and others (eg. Whales) might be measured in T (I know 1 Ton = 1,000 kilograms = 1,000,000 grams = ~2,000 Lbs. for reference). You likely need to figure out the average intake per pound across the various Species. I believe your question Title specified Wyverns, which I believe are regularly Cold Blooded, Egg Laying, Reptile types, which would make Snakes a good comparison, you probably want slightly larger than "Titanoboa" (extinct Ancestors of modern Snakes), depending upon Size and Activity Levels you might need to adjust accordingly. One hypothesis I've heard for real Dragons being currently extinct is simply a Lack of Food, they were so Massive, that they couldn't Hunt anymore, probably didn't even have enough Energy to Fly, it simply starved to Death in a field somewhere in most cases, our at least that's the Theory. If you can at least figure out a decent average intake, you should be able to get a decent portion for your Flying friends. [Answer] The bird would need to be at least 100 lbs. 300lb would be a better guess. Wing span, would be really immense, and probably have to be kinda fast beating to make it smaller. Such as 20ft wingspans. I would guess they would need to eat up to 1/3 their weight each day. Chicken is 750 calories per pound. A 100lb wyvern would need 75K calories minimum per day. Up to 225K calories, or 25 chickens per day, for the 300lb wyvern. [Answer] Science-based: A flying creature cannot carry 200 lbs on its back, so determining how much food such a creature needs is impossible. The world record for largest lift weight by a flying creature is a bald eagle that lifted a 15 lbs mule deer. Alaskan bald eagles (such as this one) have been known to weigh more than 17 lbs. There's no note as to how far this particular eagle was able to lift this particular mule deer, but it's likely not far. Generally, eagles are considered able to fly normally while lifting half their body weight. Say we're generous, and eagles can fly normally with 3/4 of their body weight. That means a 17 lbs eagle can fly normally with a 12.75 lbs animal in its claws. Or, in other words, a 17 lbs eagle can lift about 30 lbs in the air (its own weight plus the weight of the animal it's carrying). Let's now talk about the largest known flying animal, the [quetzalcoatlus](https://en.wikipedia.org/wiki/Quetzalcoatlus), which probably weighed around 500 lbs (if we're feeling generous; other estimates place its weight around 150 lbs). Now, you may think we're golden, because 3/4 of 500 lbs is 375 lbs. But, we have to take into account the square-cube law. Simply put, the square-cube law states that while area of something (for instance, wing surface area) increases at a squared rate, the mass will increase at a cubed weight. Bird lift generation is directly proportional to the surface area of the wing. The wing chord of a large bald eagle is 27.2 inches. The wingspan is 90 inches. Let's be extra generous and say that the entire bird counts as wing, and the entire wing is the width of the chord. That gives our bald eagle 2448 square inches of wing (17 square feet). So, 17 square feet of wing can lift 30 lbs into flight. Hold that number. Quetzalcoatlus had a wing span of 36 feet and a wing chord of about 4 feet. Using our same generous estimates, quetzalcoatlus had a wing surface area of 144 square feet. Quetzalcoatlus' wing surface area is 8.5 times the wing surface area of the bald eagle. 8.5 \* 30 = 255 lbs. Our back of the napkin math states that quetzalcoatlus can't even fly its own weight if we use the largest weight estimates quetzalcoatlus. But, maybe that's because our wing estimates are double what they should be (bird wings are more like triangles than rectangles). Let's run the numbers again, but with bald eagles having 8.5 square feet of wing and quetzalcoatlus having 72 square feet of wing. This makes quetzalcoatlus' wing surface area 8.5 times the wing surface area of the bald eagle... which is exactly the same number we got before. The important point here is that the relationship between the two needs to be correct, not that the exact numbers are correct. We can see the same thing happen with land-bound animals that scale up: an ant can lift many times its body weight, a human cannot. An elephant that jumps down from a chair will break its own legs. Similarly, a shrike is said to be able to lift much more than its own weight, while a bald eagle can't even lift its own weight. Extrapolating out to a size that could carry itself plus 200 pounds, such a creature cannot exist on a planet with Earth gravity and atmosphere. The other major problem with this scenario is the phrase "on its back". I want you to flap your arms and pay special attention to your back muscles. Now imagine doing the same thing in midair with 150 lbs strapped to your spine. To be able to fly, creatures need unrestricted range of motion for their shoulders and back muscles. The only way to strap something to the back of a flying creature is to strap something that's so small the creature barely notices it. In our case, that would mean something many, many times the size of the largest ever flying animal. But, even if you put people in a basket the wyvern carried in its feet, it would still never get off the ground (as illustrated above). See [this answer to a meta question](https://worldbuilding.meta.stackexchange.com/questions/2667/dealing-with-sense-of-scale-in-space/2684#2684). This question is based on false premises (a flying creature that could carry 200 lbs on its back in a `science-based` world). From the `science-based` tag description: "For questions that require answers based on hard science, not magic or pseudo-science, but do not require scientific citations." (emphasis mine) ]
[Question] [ What can a country do to become self sufficient in isolation and can it improve its technology as fast as countries such as the USA, Japan, or Russia? [Answer] Tricky question. Isolation is not a problem, per se, as long as the country has access to more or less everything that is needed to produce the topmost technology of the time - oil wouldn't be necessary in roman times, or maybe in the XXIIIth century, but an isolated country without oil today is pretty much doomed if it can't trade with anyone else. The problem with isolation is that most of the time innovation comes through competition, and an isolated country does not have anyone to compete against, which makes it to stall. Ancient Egypt through its middle period, Japan under the shogunate or China up until the british empire came in are examples of very powerful countries which paid dearly their isolation by falling back in technology and science against the rest of the world. Ancient Greece, however, developed amazing scientific progress (and an awesome military prowess) with nearly no contact with the external world, but they weren't a country, in the modern sense, but a lot of independent city-countries (poleis) which were constantly fighting among themselves, and they weren't really isolated - they had contact with egyptians, Phoenicians and other civilizations around. In theory, you could force development through competition between your own country, but that's easier said than done. Competition is usually a death match where there's only a winner and losers are obliterated. Even if it's not a military contest, it's the same with economical competition: a company will always try to crush the competence and become a monopoly. A rich region will grow rich by making the rest of country poorer. If that can't be done - because competition is tough or there are laws trying to promote equality in the competition - then they usually settle for regions of influence (companies colluding in prices, banks scheming to set a common rate of interest, states are forbidden to raise or low taxes to foster external inversion, etc...). In the end, the amount of intra-country competition and its fierceness is way lower than the one you would suffer at the hands of external competitors and so your innovation pace starts falling back behind that of the rest. [Answer] It's very unlikely that any isolated country will independently match standard of living AND technology development of more open countries. Self sufficiency (isolation) ignores the economic theory of comparative advantage. Trade between different societies enriches both - in terms of real wealth. This doesn't matter much in subsistence-level cultures, where most of the economy is centered around food and shelter. But it matters a lot when people want silk and gunpowder and fine steel and banking and washing machines and smartphones. Basically, this means that an isolated economy is likely to be poorer (lower standard of living) and develop more slowly than a comparable trading economy. It doesn't help that the politics that led to isolation also often lead to corruption and cronyism...which sap the vitality of the closed economy even further. Trade in ideas does not work the same as trade in goods and services...but foreign concepts that challenge the status quo are very important to progress in science and technology (and art and music and fashion, etc.) It's certainly possible for the isolated economy to match some carefully-chosen standard-of-living benchmarks (at the cost of distorting the rest of the economy), and it's certainly possible for the isolated country to match some carefully-chosen technological benchmarks (North Korea has nuclear weapons). But matching a wide net of those measures seems highly unlikely. This has been a challenge for closed regimes since the 1850s - they want the progress, and they want the smartphones for their ruling class, but don't want their people to see the disparity in living standards and become annoyed. An excellent example of this challenge is China before and after opening in the 1970s. [Answer] You answered your own question partially. Russia is such a country. Because it covers a lot of territory it has access not only to most wanted ingredients (which are needed for innovation), but also can sustain itself with its own food. On the other hand Korea and Myanmar (Burma) are very isolated, but rely on outside help and export of their goods and services to sustain themselves. Japan, on the other hand, made great innovations, but by using existing patents. So their technology improved because they came out of isolation. BUT Japan is also an example of a country that shows that a certain technological level is enough for a country. Keep in mind that the USA made technology leaps thanks to immigrants and non-native scientists. [Answer] Japan isolated itself to the point that Japanese overseas were not allowed to come back on pain of execution, and changed its social and industrial system incredibly quickly. All that was needed was the hierarchical authority structure to enforce it and the resources to power it. So a ruthless authority with clear goals and near total power and the natural resources in terms of ores and food to feed the human resources and industrial machine, and a focus on education and incentives in the requisite areas. ]
[Question] [ Is it possible for life to evolve— and survive— on a planet that is regularly hit by [relatively small— usually no more than a few feet across when they make an impact] meteorites? If so, what effects would this have on the creatures/civilizations living there? [Answer] The hypothetical planet sounds remarkably like planet Earth. > > Small objects frequently collide with Earth. There is an inverse relationship between the size of the object and the frequency of such events. The lunar cratering record shows that the frequency of impacts decreases as approximately the cube of the resulting crater's diameter, which is on average proportional to the diameter of the impactor.[5] Asteroids with a 1 km (0.62 mi) diameter strike Earth every 500,000 years on average.[6] Large collisions – with 5 km (3 mi) objects – happen approximately once every twenty million years. > > > Source: [Impact Event](https://en.wikipedia.org/wiki/Impact_event) Remember three-quarters of the Earth's surface is ocean and the land surface area is mostly uninhabited, so meteorites two or three feet across on impact could be happening all the time and we wouldn't notice a thing. This means life could evolve and survive without too much trouble. Open a window, look outside and appreciate this is the sort of planet you are living on, and Earth didn't have too much trouble allowing life to evolve, survive and thrive here. [Answer] Besides [a4android's discussion on the similarities of your planet to Earth](https://worldbuilding.stackexchange.com/a/75028/29)... [A sphere has an enclosed volume](https://en.wikipedia.org/wiki/Sphere#Enclosed_volume) of $ \frac{4}{3} \pi r^3 $. For a 1 m (a little over three feet) diameter sphere this becomes 0.52 m$^3$. (You can see intuitively that this is the right order of magnitude as the enclosed volume of a sphere is a fair bit smaller than the enclosed volume of the smallest cube that can fully contain the sphere.) Meteorites of course aren't perfect spheres, but to a first order approximation, this works. [Basalt](https://en.wikipedia.org/wiki/Basalt) is pretty typical as far as space rocks go, and has an [average density](http://www.ukm.my/rahim/gravity%20lecture(MSc).htm) of about 2.99 Mg/m$^3$. Thus our sphere has a mass of $ 2.99 \times 0.52 $ Mg or 1,566 kg. Heavy in human terms, but still fairly lightweight as far as above-pebble-sized space rocks go. Ignoring the atmosphere, an incoming mass will be accelerated roughly to the planet's escape velocity. [Earth's escape velocity](https://en.wikipedia.org/wiki/Escape_velocity#List_of_escape_velocities) is about 11.2 km/s. Because the appreciable [atmosphere is only a few tens of kilometers thick](https://en.wikipedia.org/wiki/Atmosphere_of_Earth#Pressure_and_thickness), the meteorite won't have time to be slowed down appreciably, particularly if on a direct, head-on impact trajectory. (A gracing impact would be different, but the head-on impact is the worst case scenario as far as collision energy is concerned. The absolute worst case would be a head-on retrograde impact, which would effectively add the orbital velocity kinetic energy of the planet and the kinetic energy of the impactor, as velocities are always relative each other. For a retrograde impact, however, you have to figure out how the rock ended up in a retrograde orbit in the first place.) Ignoring [relativistic effects](https://en.wikipedia.org/wiki/Kinetic_energy#Relativistic_kinetic_energy_of_rigid_bodies), the [kinetic energy](https://en.wikipedia.org/wiki/Kinetic_energy#Kinetic_energy_of_rigid_bodies) of a rigid object is equal to $ \frac{1}{2} mv^2 $. When mass ($m$) is measured in kg and speed (velocity, $v$) in m/s, the resultant value is in [joules](https://en.wikipedia.org/wiki/Joule). The kinetic energy of our impactor is about [98 GJ](http://www.wolframalpha.com/input/?i=kinetic+energy+of+1566+kg+moving+at+11200+m%2Fs) if it hits Earth in such a way that we can ignore Earth's orbital velocity; say, from straight above one of the poles. Your planet will probably have a different mass and thus a different escape velocity, so you should adjust accordingly. To put the number 98 GJ in perspective, Wolfram Alpha provides some [nice order-of-magnitude comparisons](http://www.wolframalpha.com/input/?i=98.22+gigajoules). For example, it is about 27,300 kWh (on the order of what you need to heat two houses for a year in a northernly climate) or the energy obtained by total fission of about 1.2 grams of uranium-235. In other words, a perhaps surprisingly small amount of energy. Such an impact will pretty obviously have significant local consequences, but the global or even regional consequences should be small especially as this presumably doesn't happen every day. Overall, life should have little difficulty coping with this, but some particular evolutionary strategies are likely to be heavily selected against, such as... Keep in mind that if your planet is Earth-like, then most of it (in the case of Earth, about 2/3) is covered by water. A water impact near land might make things unpleasant for beings living near the coastline, but if your planet suffers regularly from this, then the resulting selection pressure will pretty quickly cause those beings to move inland. [Answer] [Cowboy Bebop](https://www.imdb.com/title/tt0213338/) [Session 09: Jamming With Edward](https://dotandline.net/cowboy-bebop-jamming-with-edward-228f391ef6ff/) describes an Earth that has become widely dysfunctional due to incompetent governance, culminating in a manmade disaster (partial destruction of Luna) that causes a persistent meteor bombardment of the Earth's surface. The frequent and repetitive meteor damage is a strain on civilized life everywhere on Earth, and is realistically depicted as the major factor preventing economic recovery. You should inter alia watch this episode if you plan to write about a bombarded inhabited planet. [Answer] The film "Enemy Mine" features a planet that frequently receives meteor showers, the life that has developed there is very turtle-like. Assuming your suggested impact size and an extremely high frequency of impacts, the planet would probably have a very rugged surface and a lot of dust in the atmosphere, but other than that it is not too much of a factor if it is constant. Life is generally more dangerous due to risk of direct hits, and evolution would have to adapt to protect life from additional impact debris, but ideally from direct hits as well. I don't believe turtle-like life might be ideal, but rather something closer to insects with hard exoskeletons that are able to dig themselves into the ground for protection, and without the risk of being trapped if their tunnel network collapses. The flora would depend on how competitive it is, it could probably develop to be very earth-like due to low risk of direct hits. I was about to say that I'd expect smaller plants due to the dust in the atmosphere, but the power output of the star might make up for it. [Answer] Much depends on frequency and size. A cubic meter or so of rock takes out a good chunk of town. See Michael Kjörling's answer. Suppose that a U.S. sized nation got 10 a year. This would likely mean every few years one would hit some place important. It would be a Katrina Hurricane or Los Angeles earthquake sort of event. If it's one per square mile per year, I don't think it's survivable. It takes fewer larger rocks. Near coast ocean strikes are probably more damaging. As a model consider this: Pioneer societies had a doubleing time of about 1 generation. E.g. on the average pioneer societies raise 4 kids per couple to maturity. So you can kill off 50% of the people per generation and probably deal with it. Assume forest fire type regrowth of impact sites. Within 5 years you will have something densely green on the site. Assume also that for every square km destroyed outright, that there is a similar area effectively destroyed but spread out. E.g. 1 km2 destroyed and 10 km2 that is 10$ less productive or 3 km2 that is about 30% down. So you could probably impact 25% of y9our land mass per generation and have it survivable. ]
[Question] [ Imagine a world with time travel, got it? Good. Now imagine that time has multiple dimensions. Time has its OWN dimension of time, along which it can evolve. This is called hypertime, or "w" (As in w,x,y,z,t). Now imagine a WH40K style world-government for humanity, that wants history to stay EXACTLY as it is. Time travel is the in-universe equivalent of heresy and any attempts to prevent the presence of our Lord and Emperor are also Treason. When FTL travel is discovered, the TPA is set up to protect history. (This is of course after the Emperor uses it to become Emperor. "After" in the sense of "w" not "t".) So yeah, laws are made against changing time, and a government agency is set up to make sure there's no time-spirals that could cause instability in the timeline. (Closed Time-Like Curves in relativity look like spirals when you add in the hypertime dimension.) They can't move or detect ANYTHING that is in the "hyperfuture". They can use probes or whatever to detect anything in spacetime, but not hypertime. Hypertime passes when the events IN time are changed, so as history changes, hypertime progresses. Time is where space evolves, hypertime is where spacetime events evolve and it only makes sense to think of hypertime passing as events in history are changed. The Questions are: How do you detect time travel? What is the simplest way to have a time agency keep a record of the "TRUE" history. What is the least handwavium way to have them detect that they've progressed in hypertime? [Answer] Create as complete of a record of the past as you can. Make two copies of it on read only media. Store the backup copy either in a dimension in a separate timeline or, if that isn't possible, in the very far past of your timeline. Then leave a portal open that allows communication. Have the backup copy, in a continuous loop, transmit its data through the portal. Have no communication to the backup location. Destroy any records of the backup location and kill anyone who knows where it is. Use that to check your copy against the backup copy. [Answer] There is a theory/hypothesis about time. Namely that all time has already happened. Basically, time, like any other dimension, is, relatively, static. We as humans are not capable of perceiving all of time, just like we are incapable of perceiving all of space. However, we do have the technology to monitor all of space (though some limits apply and your results may vary). So what your TPA needs is to send a satellite into outer time. Or in more official terminology they need a detector that can monitor time (t) and hypertime (w). Since the TPA is aware of w, it means they can observe w. They can measure w and its interactions with regards to t. Once you have such a sensor, you just have to calibrate it and produce multiple of them. You calibrate the sensor with theoretical values adjusted for the background noise in w. A semi decent example is [LIGO](https://en.wikipedia.org/wiki/LIGO), it detects the bending of the fabric of space time due to gravitational waves based on knowledge of the speed of light, among other things. Another is [GPS](https://en.wikipedia.org/wiki/Global_Positioning_System). GPS works on our knowledge of gravity's effect on time, among other things. That said: it will require that your world has a sound theory of the general relativity between w and t, because that's how your sensor is going to have to work. But since the TPA can observe w and draw relationships between w and t, this really shouldn't be that hard. The easy part is after that. They detect an anomaly as based on their measurements, narrow it down to its XYZT coordinates, using Hyper General Relativity, and viola. You got your perp. [Answer] If the TPA is so vehemently opposed to time travel that they aren't willing to even do it themselves to keep others from doing it, I believe it's impossible without some way of intercepting time travelers in $t$ before they go back in time. If they can look forward in $t$, and depending on the details of your scenario, this may be possible. However, if they are willing to go back in time themselves ("for the greater good"), and there is no such thing as the butterfly effect, and time criminals are altering time in order to change historic events, there's a simple solution: the TPA can place a secret base of operations in prehistoric times. This way, they can periodically send agents (or look forward in $t$, again, if that is possible) to check the historical timeline for meddling, similar to @DJClayworth's answer. However, now when time is meddled with, the TPA don't have to worry about their base being erased from existence, because the base's $t$ is before the alteration's $t$, and they can merely intercept the offending time traveler when in $t$ they arrive and detain them (probably permanently, so that no one can reveal their secret). There's plenty of opportunity for interesting plot complications with this: * Someone accidentally discovers the existence of the secret base and is pursued by the TPA through hypertime. * Someone wants to alter history, but knows about the secret and mounts an attack on the prehistoric base in order to disable it first (in $w$). * etc. Of course, if a time traveler goes back to prehistoric times and changes something, either on purpose or accidentally (à la [A Sound of Thunder](https://en.wikipedia.org/wiki/A_Sound_of_Thunder)), nobody can do anything about it, and depending on the details of your scenario, the base might get erased from existence. Equally of course, most of this is invalid if the TPA won't use time travel themselves. EDIT: As @JoshKing so kindly pointed out, this is very similar if not identical to Poul Anderson's Time Patrol. This probably makes the above more likely to be valid but less interesting in any case. [Answer] I think you need to firmly decide what happens to the present when an event changes Hypertime. There are a few possibilities: 1. The change overwrites the current "time." The changes are part of history and always have been. This would corrupt/overwrite whatever checking mechanism you can device that is within the same timeline. The plus side is that the Empire can honestly say that they have not detected any corruption to the timeline. 2. The change splits off a parallel universe. People of Universe A maintain their original timeline, but Universe B has the new timeline. These sorts of changes could be detected, and, assuming that you can cross into a new parallel dimension, could be "eradicated" by destroying the parallel universe. The original timeline would remain safe (though, in theory, if there was a Universe B version of the Temporal Inquisition, they would believe they were the originators and try to destroy Universe A in a similar way). 3. The change causes a "shockwave" that slowly changes the current Timeline to the new Timeline. This could be detectable by scanning historic events and comparing them to a database. It will also create dramatic tension, as once the "shockwave" reaches the current timeline, it will overwrite the current timeline. My personal favorite is 2, as it can be the basis for time wars. By the time the story occurs, there could be infinite parrallels, with war raging between many of them. [Answer] Every so often in w, you check key events. It's assumed that if you can jump to a specific point in t you can also investigate events in t (possibly by jumping there very very discreetly), and check that they are happening like you expect. Night shift guy at the TPA has to do this. > > Routine check of 1946. Wait, Hitler not dead? Press the big red alarm button! > > > In answer to comments, I am assuming changes to the timeline don't affect people in W. Night shift guy then has a simple check list based on the expected state of things in 1946. 1. Hitler dead 2. Atomic bomb dropped 3 Montreal Canadiens won Stanley Cup. The list isn't affected by changes in the timeline (If they were, how would anyone ever know the timeline had been changed). ]
[Question] [ With all the interest in VASIMR and the idea of getting to Mars in 39 days, the biggest challenge I can see is having a power source that is strong and light enough to make that possible. So I was thinking, shouldn't a Dyson-Harrop satellite built into some hypothetical spaceship be able to easily provide the energy for the ion drive? According to [Wikipedia](https://en.wikipedia.org/wiki/Dyson%E2%80%93Harrop_satellite): > > A relatively small Dyson–Harrop satellite using a 1-centimetre-wide > copper wire 300 metres long, a receiver 2 metres wide and a sail 10 > metres in diameter, sitting at roughly the same distance from the sun > as the Earth, could generate 1.7 megawatts of power – enough for about > 1000 family homes in the US. > > > Considering that this would be attached to a spaceship, the sail could be discarded and the Dyson-Harrop is able to be scaled up and down and be used anywhere (for the most part) in the solar system. So is there something I'm missing here that makes this infeasible? Because to me this seems like a relatively cheap and easy way to power fast ion drives. [Answer] I haven't been able to find much in the way of alternate primary sources for a Dyson–Harrop satellite. The [NewScientist article](https://www.newscientist.com/article/dn19497-out-of-this-world-proposal-for-solar-wind-power/), which is the proximate source for e.g. Wikipedia, references [this paper](https://www.cambridge.org/core/journals/international-journal-of-astrobiology/article/div-classtitlethe-solar-wind-power-satellite-as-an-alternative-to-a-traditional-dyson-sphere-and-its-implications-for-remote-detectiondiv/DF6FBB8CDCA6C74B31EEF900494497DA) in the International Journal of Astrobiology. I don't have access to this journal, but more-technical commentary on it [is available here](http://www.lpi.usra.edu/meetings/abscicon2010/pdf/5469.pdf). --- The wording of the analysis as well as common sense tell me that the satellite is moving slower than orbital velocity, possibly not at all, and is buoyed up by reaction from decelerating the solar wind. Indeed, this is unavoidable. So, the first problem, I should think, is that your spaceship will have an additional radial thrust vector (though depending on the transfer orbit, this may not be undesirable). The second problem is whether the scheme actually works. I'm skeptical that the system provides enough power to maintain its own magnetic field, but I don't know enough to reason about that scientifically. From an energy-balance perspective, it checks out okay though (energy is captured from solar wind, and in-principle there's nothing wrong with expending some energy to do this). Addionally, I'm skeptical the amount of energy to be gained is in the megawatt or even kilowatt range. Perhaps this is discussed in the journal article in more detail. It's worth noting that mass is reasonable. The copper wire is ~200 kg, which is about 1/5 the weight of the Dawn ion spacecraft. I'd bet this is comparable to the mass of Dawn's solar panels, which produce 10kW (or ~1/100 the power of this scheme, if it worked). As far as I've analyzed, nothing here is a definite deal-killer. I'd say it's plausible. In-particular, if you believe the claims for a satellite, there's nothing preventing you from using it to power a spaceship (which is after all merely a satellite designed for SOI changes). --- (N.B. I'll agree in-principle that physics.stackexchange is a better fit for this question, but in-practice the only nontrivial questions they seem to favorably receive are related to GR/SR and, in-particular, any speculative applications of Physics are right out.) [Answer] I found information in this article helpful to the question presented. [The Solar Wind Power Satellite as an Alternative to a Traditional Dyson Sphere and Its Implications for remote Detection](http://articles.adsabs.harvard.edu//full/2010IJAsB...9...89H/0000089.000.html). And while this answer does not focus on if a Dyson harrop satalite could generate the kinds of power reported, this answer addresses two potential issues with the original posters suggestion, and is quoted below. > > Considering that this would be attached to a spaceship, the sail could > be discarded and the Dyson-Harrop is able to be scaled up and down and > be used anywhere (for the most part) in the solar system. > > > --- 1. As to power levels and anywhere in the solar system: The figures quoted from Wikipedia were based on an article that described a Dyson Harrop satellite positioned in an orbit at 90 degrees to the solar equatorial plane to pass through more energetic fast solar wind particles. Furthermore, the high orbital inclination contributed to the issue of how to "beem" energy back to Earth over very great distances. Unfortunately the stated power levels are not applicable to a space ship traveling between planets. All of the planets in our solar system, for better and worse, orbit the sun with an orbital inclination just few degrees from the sun's equatorial plane, thus only experience intermittent and relatively slow solar winds. Maybe it is still possible for an inter planetary space craft to directly collect some energy with this kind of solar wind energy collector, but it will be neither consistent or at the same power levels quoted for a Dyson Harrop satellite, because those numbers were generated for a different scenario. 2. As to doing away with the sail: The Dyson Harrop satellite relies on the photo electric effect where photons eject excess electrons off the sail which seems to indicate better power with a larger surface area (with in a reasonable limit), as one may find in a sail. Maybe the ship could be the Dyson Harrop electron receiver. --- Supplemental information: Fast wind is dominate at more than +30 degrees from the solar plane International Journal of Astrobiology, Volume 9, Issue 2, p. 89-99; Figure 4 of page 92 [![Solar wind](https://i.stack.imgur.com/p2M2G.png)](https://i.stack.imgur.com/p2M2G.png) [Planetary orbital inclination](https://en.wikipedia.org/wiki/Orbital_inclination) [![Orbital inclination table](https://i.stack.imgur.com/qf4bI.png)](https://i.stack.imgur.com/qf4bI.png) [![Dyson Harrop Satellite](https://i.stack.imgur.com/GekGX.jpg)](https://i.stack.imgur.com/GekGX.jpg) --- Commentary: Unfortunately for solar wind powered space travel between planets, the plants's orbits are in the slow solar wind region. And while a high orbital inclination is unlikely for a planet to form in, we may say Earth's atmosphere is lucky that Earth's orbit does not have an inclination that alternatingly takes us through the Sun's more powerful fast solar winds every 6 months or so. [Answer] It seems the inventor claims: "A satellite with the same-sized receiver at the same distance from the sun but with a 1-kilometre-long wire and a sail 8400 kilometres wide could generate roughly 1 billion billion gigawatts (10^27 watts) of power, “which is actually 100 billion times the power humanity currently requires”, says researcher Brooks Harrop, a physicist at Washington State University in Pullman who designed the satellite." That is remarkable. Because that is almost 3 times more than the whole power output of the sun, which is about 3.8x10^26. ]
[Question] [ In a world I am building, a race of humans exists on a tropical archipelago with a very hot climate. Their skin, naturally, is very dark, but I want to have their eyes [most, if not all of their eyes] be light grey. Is this possible? [Answer] Yes. Blue eyes are actually made by a lack of melanin in the iris and other colours a variation on this. (Blue is caused by the refraction of light around the iris, same reason the sky is blue). We do, in fact get [black people with blue eyes](http://afritorial.com/black-people-with-blue-eyes/) in humans. They are a minority but still do exist. So yes, grey eyes are also possible for your humans. [Answer] Very dark skin with very light eyes is maybe genetically possible but extremely unlikely. Brown eyes have dark melanin. Blue-eyed people lack this melanin and their eye tissue is colorless (the blue is a result of light scattering, same reason the sky looks blue)…. It's not a coincidence that people who lack melanin in their eyes would also lack it in their skin, hence blue eyes are most common in Northern Europe among very light skinned people. Grey eyes occur in North Africa, the Middle East, and Asia. [According to this website](http://genetics.thetech.org/ask/ask232) the exact genes are unknown but probably a similar combo to the blue-eye genes. Again these are not "very dark" people. Think of the famous "Afghan Girl" from the magazine cover Her eyes are green but very light: [![enter image description here](https://i.stack.imgur.com/durcJ.png)](https://i.stack.imgur.com/durcJ.png) To get around this, you'd need a genetic combo that codes for lots of melanin, but with a defect so the melanin is blocked locally in the cells of the eyes. It's possible, but then you'd need to replicate that gene defect through the entire island population. [Answer] One way to achieve this is by selective breeding. It could be that evolution resulted in your people having dark eyes, but then one small group had a mutated gene which gave them grey eyes. For some reason this gene tends to be dominant. Over time (thousands of years), people preferred grey eyes, and tended to choose grey-eyed partners. This is selective breeding, in which male and female are selected (or select each other) in order to produce offspring with certain traits. We do this with animals today. So just make it that grey eyes are more desirable, and as a result of years of selective breeding, the majority now has grey eyes. Those with dark eyes still occur, but are the minority. [Answer] No, or at least unlikely. There is no evolutionary advantage in having blue, green or grey eyes. Pale skin, yes, in the north, but eye and hair colour are only a secondary effect of that. If your islanders are really human, it's improbable. No melanin production in the eye would be the result of a genetic defect. That would usually only proliferate thoughout a whole population if it had some secondary advantage, for example resistance to an endemic infection, even if it was otherwise completely harmless. A dominant genetic variation occuring spontaneously is something rather rare, i believe. [Answer] ## In a manner of speaking, yes. [Recently, we have found evidence that the blue eye gene stemmed from the random mutation of one individual.](https://www.sciencedaily.com/releases/2008/01/080130170343.htm) Random mutation is the key to the bulk of ethnic geodiversity here. Contrary to popular belief, for example, it was agriculture, not latitude, that created the Caucasian and Mongoloid paleness. [If it were latitude, the evidence would have shown us a case of human whitewashing far older than eight thousand years.](https://www.sciencedaily.com/releases/2008/01/080130170343.htm) The reason for the more likely connection between whitewashing and agriculture is that plant foods don't have much of the vitamin D that a dark skin needs. ]
[Question] [ The [SNECMA Coléoptère](https://en.wikipedia.org/wiki/SNECMA_Col%C3%A9opt%C3%A8re) was a French VTOL plane that was fairly successful in testing but could not get funding to build a second prototype after the first one crashed on its ninth flight. After that the project was scrapped. Looking at this plane, one can see why some people may have thought it was silly: [![image of the Coléoptère](https://i.stack.imgur.com/QXWLg.png)](https://i.stack.imgur.com/QXWLg.png) But one does wonder. What if they had received the funding? Obviously I'm not asking that as it would be beyond broad, but I do need a reason to follow this line of thought. What is the smallest feasible change I could make to history for the SNECMA Coléoptère Mark II to get funding? [Answer] Ideas like the Coléoptère, "Pentomic" Divisions, converting militia regiments into "Civil Rescue columns" and numerous other plans (some more feasible than others) were all responses to the idea that the threshold for nuclear weapons release would be very low (indeed there was and is a school of thought the USSR would begin the "Liberation" of Western Europe behind a decapitating nuclear strike). All these ideas were meant to allow forces to continue to operate in a post nuclear environment. As an incidental, the Soviet BMP-1 was also developed for this environment, allowing troops to cross contaminated battlefields and even fight mounted. (Misunderstanding of this role led to the Western development of the Infantry Fighting Vehicle or IFV, and when the realization that using nuclear "fire corridors" to clear the axis of advance was't a particularly smart idea, the Soviets were stuck with several thousand of these vehicles, which they repurposed into IFV's....) [![enter image description here](https://i.stack.imgur.com/obL1m.jpg)](https://i.stack.imgur.com/obL1m.jpg) BMP-1. This picture is after the BMP became an IFV (hence the dismounted troops). Later developments included changed tactics, and by the late 1970's the BMP-2 with a two man turret and a 30mm cannon While these ideas were being developed, tested and in some cases fielded, it became apparent that the idea of decapitating nuclear strikes and low thresholds of nuclear weapons release were counterproductive (to say the least), and many of these ideas turned out to be rather fragile or unsuitable for operations either in regular military environments post nuclear environments. To continue development of the Coléoptère, two things have to change: 1. The futility of low thresholds of nuclear weapons release is not recognized or acknowledged, and; 2. The technical issue of landing a Coléoptère can be addressed. Tail sitters like the Coléoptère, or the "Pogo" are easy to take off and often joys to fly due to the enormous power to weight ratios (the Convair "Pogo" would have been virtually unbeatable in a dogfight, for example), but pilots had terrible difficulty judging ground approach when attempting to land "tail sitters". This might have been corrected by some sort of radar altimeter and autopilot, although the state of the art really wasn't sufficiently developed. As well, even if we assume the Coléoptère actually performed as advertised, dispersing large numbers of ground crews, fuel trucks, ammunition trucks and security forces for each aircraft would be problematic, and indeed would have presented fairly lucrative targets on their own. [![enter image description here](https://i.stack.imgur.com/vn4UC.jpg)](https://i.stack.imgur.com/vn4UC.jpg) XFY-1 Pogo taking off The expected payoff would have to be commensurate with the investment, so the projected and demonstrated performance of the Coléoptère and its weapons systems would have to be far superior to conventional aircraft (or there would have to be a virtual certainty that there would be no conventional aircraft anywhere in a post nuclear environment. So the development of the Coléoptère would be dependent on the conditions for such a specialized aircraft to continue to be in effect, the state of the art for radar and autopilots developed sufficiently for the aircraft to safely operate, and there are no real or projected alternatives which can do the same job for a lower investment. [Answer] > > What is the smallest feasible change could I make to history for the Snecma mark II to get funded? > > > Make it work. The main problem is, that it crashed after the ninth flight. If it wouldn't have done so, funding wouldn't have stopped. --- Okay, let's say it didn't work, but some high up government official still clings to the project. The magic word is: Cross-subsidization * Make other projects cost more than they really would and fork off some money to the Coléoptère project. * Buy pens for 1 Franc per piece, while it would really cost only 0.25 and the other .75 Franc go to Coléoptère (Area 51 is funded that way, according to the Independence Day Movie) [Answer] Convince decisionmakers that it may work and that the geopolitical situation makes it necessary to try harder. * Scientific reports about overpressure damage from nuclear strikes on above-ground airbases. * Intelligence reports about the Soviet fielding of runway-cratering conventional bombs for their principal bomber force. * Early, specacular failures on other concepts like the [P.1127](https://en.wikipedia.org/wiki/Hawker_Siddeley_P.1127) and the [Do 31](https://en.wikipedia.org/wiki/Dornier_Do_31). Change the timeline on those, try thrust vectoring earlier before it can be controlled. By the way, SNECMA is the company and Coléoptère is the aircraft. [Answer] # It has potential to save money. I mean, from the looks of it, that's a disastrous design. It doesn't look particularly efficient. Nevertheless, I'm no expert. I would approach the problem by trying to showcase this plane as a wise investment opportunity. One might want to highlight the following features in the v2 model: * Fuel efficiency * Payload capabilities * Rapid ascent * Top speed Apparently, the 9th flight failed due to "insufficient instrumentation and a lack of visual benchmarks" - to me, that describes internal problems such as faulty cockpit equipment. I mean sure, the design sucks... but one might be able to argue that with newer (inside) technology the aircraft could flourish one of my potential money-saving features. ]
[Question] [ In many fantasy universes, necromancers are feared. They are regarded as generally evil, forces of chaos, and defiers of the natural order. Now consider a world like our own, where a select few use not magic but science to raise the dead. Obviously some are 'evil', rasing armies of the dead to ead attacks upon the world, but some would be 'good', trying to use their newfound 'powers' to cleanse the world of darkness. Hell, there might even be some playing a role similar to Garth Nix's Abhorsen, a style of necromancer who lays the dead to rest. My question is this: Would the use of a scientific necromancer be viable in modern warfare? Consider that: * The dead will follow the necromancer's will, but only by force. They use some kind of mind control drug-collar-thing. * Raising the dead requires a laboratory to do. It cannot simply be done on the battlfield. * Raising the dead takes a vast ammount of energy (Say 1 minute of the machines running uses the energy generated by 1 reactor in a nuclear power plant in the same time). * Due to the energy taken, only 1 necromancer can work in a location at a time. No, it doesn't make much sense, but just roll with it. * Just like regular zombies, you kill the raised by destroying the brain. Hence, the bodies must be fresh when delivered, as the brain decomposes rapidly. Bearing this in mind, would a modern army want to use these necromancers? If so, to what extent? And if not, what sort of changes would the necromancers have to make to their methods to make them viable? [Answer] You should take the captured opposing soldiers and execute them. Next, resurrect them, put a suicide vest under their uniforms, using the "mind control" make them return to their own bases, and then detonate them. To be moral about it, say that this is being done to soldiers who would have died anyway. And, say that doing this demoralizes the enemy such that the war will end sooner and thus save lives. [Answer] ## They would not, but it's an interesting story idea * You have passed the moral threshold. Of course some necromancers will have good intentions as they bring back dead veterans, then force them to die again and again for their country, without a true, respectful burial, but the public will not accept this method. Put differently, if the majority of the world rejects abortions (note that I am not trying to express my personal opinion on that topic) then seeing their comrades, friends, and neighbors brought to life to be killed again and again will in no way be more easily accepted. * The living are cheaper. Assuming you can revive a decomposing body (and keep it fresh), you will need to reteach or retrain it in order to make effective use. Unless these "zombies" are exactly like people, you will need to spend a substantial amount of time and energy providing enough basic rehab to get them fighting - let alone making informed decisions. Coordinated, healthy, living recruits, who only need training once, and who can return to their families without severe mental illness, are less expensive. [Answer] Yes but only if you make them require less energy to raise the Dead. The whole point of of a necromancer that he can produce a large army for very very cheap. All he really has to do is show up on the battlefield and snap his fingers and just like that yes a couple thousand corpses. That's what makes them so Unstoppable. Your a scientific necromancer's should not have it that easy because science is harder than Magic but still the process should be relatively quick and cheap. Otherwise no point in having a necromancer on your side whether he's using science or Magic. So yeah if you want the Necromancer to be any use to your army then either you need a lot of energy in your world we need to make necromancy cheaper. Some thoughts to consider 1. Does your zombies retain some of their skills they had in life? Could they still fire a gun drive a tank? If the answer is yes then you can see the zombies replace humans on the battlefield. If the answer is no then the zombies might still make it to the battlefield but they be used to take strategically. And most of your army would still be living troops. 2. Does the necromancy process slow down or even completely turn off the decay of the undead. If the answer is yes then you'd see a lot more zombies on the battlefield if the answer is no then there'll be a lot of battles without zombies at all. They would be used strategically to turn the tide of battle in certain situations but they couldn't be kept to use the second time so there will never be a large force of them at least not one that lasted long. [Answer] The most useful use of a necromancer like this isn't to make soldier but to collect information. Alive, people can resist torture and/or truth drugs and people might kill themselves to escape questioning but if you can question the dead, there is no escape. Osama got killed by military but imagine how much information you could get out of him if you could question his corpse? [Answer] This method is too expensive too see any real use raising an army of dead soldiers, but I can see it becoming useful by reanimating only very important individuals. If the zombies are similar enough to living humans, you can use them as spies and as a way to plant false information. You can also kill an enemy general or important politician, raise them and use the authority they still carry to disrupt the enemy issuing counterproductive orders. If it is easy to differentiate the dead from the living, they can still be used as a way to lower enemy morale, if the zombie was important/loved enough while alive. Just imagine what it would feel to have the President of the United States killed and turned into a brainless servant of ISIS. ]
[Question] [ We have a magician apprentice (let's call him Steven) and his master (Destionell the Great). Steven is serving for a long time to his master and he truly hates it. Every day all his job is just cleaning Destionells house, cooking him meals and washing his robes. And all of that without the magic of course (because you're not ready yet, the master always say to Steven). The apprentice actually never learnt a single spell and never saw a single book of them (the books are even enchanted so no one could open them without magicians knowledge), but Steven desires a hopes to be a great wizard, so he's not leaving his master despite all of this. Steven never saw his master casting any spell, but he believes him strongly, as he is well-known magician. One day Steven came up with a plan. Because he was often delivering masters mail to the nearest village, he has access to some (unimportant) handwritings of his master. Also, he is sometimes cleaning the room when Destionell is writing some spells (with a regular pen on a regular paper like the magicians always do). So Steven decides to learn how all the pen strokes and the gasps between words his master does sound. He will always listen very carefully and after a certain time, as he hopes, he will be able to find out more about some of the spells his master is writing, just by hearing. TL;DR: Is it possible to learn to recognise what someone is writing just by hearing it (if you are practising with the same person)? [Answer] # Absolutely not If the master is writing for himself, he's probably using very casual handwriting, the sort that would be used when writing letters to friends. This handwriting is going to be in cursive - and cursive is written in a continuous stroke. If Steven had a supercomputer, a massive archive of perfectly reliable data, and the ability to write machine learning software, he could maybe analyze the sounds of individual words, but he will never get letter accuracy. And then you get to the other problems inherent in writing on paper. The magician crossed something out or underlined something. Where? You have no idea. The magician paused in the middle of a word. Is it a new word when he starts writing again? You can't know. The magician scribed a diagram? Good luck reproducing it. The master wrote something in bigger size? The sound just changed. The master is writing on different paper, or with a freshly sharpened quill? The sound just changed. Add to that the fact that Steven can't sit there writing it down as he hears it. He needs to have 100% perfect memory, and even then he's guaranteed to screw up and accidentally open a portal to the Far Realms or something. [Answer] It should be possible, even though extremely hard. It is a somewhat-common party trick to recognize what other person is writing with wet finger on a glass table without looking at it, but the sound produced is quite loud, and the other person is purposefully writing slowly. Recognizing pen writing should be possible using the same principle, although much harder, as sounds are more quiet, and magician is probably typing faster, which would make it harder. Than again, paper grain should make vertical strokes easier to tell from horizontal ones, if your ear is keen enough to hear them at all. Some magical hearing-enhancement drug should make it a breeze, but it is not "impossible" even without it. Limit here is that apprentice would need to know language magician is using - letter recognition would not be perfect, and he would often need to rely on context to tell whole words, which makes magical incantation in ancient languages impossible to decipher with 100% accuracy (plot device detected). [Answer] # Yes It is certainly possible for Steven to figure out what his master is writing, with a few foundational assumptions. 1. Steven must have a very acute sense of hearing, a musical background will be of great assistance. 2. The language and general writing style used in the casual letters and notes that the Wizard uses are the same, otherwise it would be impossible to learn how to compare and correlate the stroke sounds to the writing. 3. Steven is either given enough time to perfect this skill to the point of being able to speak out the words just based on the strokes, and/or has Eidetic/Photographic -grade memory so he can reconstruct passages later (especially true for alphabet-based writing). Alternatively, he could just write as he listens from a different room. 4. The writing is done in a language with some sort of pen-stroke system, and strokes are done in a sequential order to create letters/words. More importantly, each word/letter should have mostly distinct strokes. (Cursive is a special case that does not fall under this category, and surely if his Master writes in cursive, Steven isn't quite mad enough to attempt to distinguish between entire words in cursive by sound alone). 5. Credits to AlexP for mentioning that some languages, like Arabic, are strictly done in cursive form. If Steven's master is writing in an Arabic-like or strictly cursive language, Steven should just give up on this venture and find a master that writes in a different language. 6. There is a distinct enough gap between letters when writing, otherwise there will be a lot more work involved in figuring out which strokes belong to which letters. # Process ## Stroke Categorization Steven must begin the process by figuring out a system to categorize the strokes. Example Alphabet: [![Alphabet-based language](https://i.stack.imgur.com/kFI10.png)](https://i.stack.imgur.com/kFI10.png) As can be seen from the image, each letter of the alphabet has a distinct number of strokes, and in a set order (which some individuals do differently, but the order for each letter can be analyzed through seeing and listening to the pen strokes of the Master’s casual letters). The strokes forming the letters of the alphabet can be categorized into a few distinct types: straight, curved, dotted, and angled strokes. The length of each stroke can be determined by listening to the duration of each stroke: short, medium, or long. If Steven can train his ears to hear the differences between each type of stroke and the length, using this system he can construct a sequence of writing sounds into a series of strokes, letters, and subsequently sentences. ## Example: ``` S- straight stroke C- curved stroke D- dot stroke A- angled stroke 1- short 2- medium 3- long "A quick brown fox" s3s3s1 A c2s3 c1s1 ds1 c2 l3a3 q/g u/n i c k l3c2 l1c1 c3 a2a2 s1c2 b/d r o/s w n s1c3 c3 s1s1 f o/s x Autocorrecting process: 1. Agnickdrownfsx 2. A quick drown fsx 3. A quick brown fox ``` ## Practice and Results By piecing together each letter combo, and eliminating the incorrect letters, Steven can reasonably hope to piece together entire sentences, of course, with some errors. It will take a long time before he could do it for everything that is written, but when he masters this, it should be enough for him to begin his journey into magic, so that he may catch the attention of his master and finally get a chance to learn in earnest (or at least [animate some brooms to do his chores](https://www.youtube.com/watch?v=Rrm8usaH0sM)). # Bonus: ## Symbol-based language: [![enter image description here](https://i.stack.imgur.com/sAd57.png)](https://i.stack.imgur.com/sAd57.png) It may seem more difficult to deal with a symbol based language than an alphabetical one, but in actuality it can be made much simpler, since each stroke type in these languages are more well-defined (see how each stroke has various defining features). Assuming, every 'word' constructed of such strokes is always written in the same order, it is possible to construct it in unique, less repetitive strokes compared to a phonetic language, with much less mistakes in determining which word/symbol has been used. The words can then be recombined to form sentences. ]
[Question] [ Lightsabers are cool, regardless of your opinion of the movies, lightsabers are really cool. From the fact that it can retract the blade to the lack of effort needed to cut through anything only makes them seem even better and I feel I speak for many science fiction writers when I say I wish I could use them, but unfortunately unless you are writing a fanfiction, you are out of luck. Many series that really want to use lightsaber-esque weaponry tend to use a weapon similar to them like Halo's energy sword or Bleach's laser swords. I am asking if there are any other options. I am not looking for the down and dirty, hard core science details of such a weapon, rather the simple and basic. What weapons (real or fictional) would be able to match the lightsaber in its usefulness and functionality? --- Note To be clear, questions like this are very common on the site, with the correct answer often being the one that provide either the most options or the most detailed answer. [1](https://worldbuilding.stackexchange.com/questions/52351/alternatives-to-humanoid-as-a-category-in-fantasy) [2](https://worldbuilding.stackexchange.com/questions/36222/alternatives-to-dna) [3](https://worldbuilding.stackexchange.com/questions/11547/alternative-absorption-spectra-for-plants) [4](https://worldbuilding.stackexchange.com/questions/13676/alien-skin-substitutes) [Answer] Force fields as weapons You know after the first prequel came out I came up with a working hypothesis about how lightsabers operated, it was completely different than the official method. They showed they had the capabilities to produce force field with variable passage (blaster bolts go out but not in). I had assumed lightsabers were just a super hot plasma contained in a elongate ellipsoid forcefield that let any matter in but only let a small amount back out. a light saber can stop a lightsaber becasue the two fields repel. Their power source last forever because so much of the heat is conserved because it cannot escape. That would explain how they don't burn the wielder and how it carves such neat holes instead of creating a fountainous spray of molten material like a plasma cutter does. Now you can use that as is or take the next step and use force field based weapons without bothering with plasma. Imagine if you could creating a cutting edge made of wedge shaped force field or even a planar one. The cutting edge is no longer restricted by atoms or bonding strength but on how precise your mathematics and emitters are. You can make a subatomic cutting edge, that would cut through normal matter like butter. And instead of a burnt hole you would just have perfect planar cut out fantasy anime, were the object is cut with no visible marks until it falls apart. for comparison the blades for preparing electron microscope slides are a few hundred atoms wide and will cut through your hand as easily as they cut air. At subatomic edges you could cut anything as easily as cutting air, except another force field. Forcefield could also be used to get other shapes so you are not limited to sword shapes, in fact a bet the cutting fields would have a huge number of industrial uses. bonus dialogue for the force swords: What's that weird fizzy glow along the sword edge when you swing? Oh, well most of the time it just cleaves atomic bonds but every so often it hits an atomic nucleus and fissions it. [Answer] ## Melee Energy Weapons ### Light/Laser Handle sends out a focused beam of light, and reflects it back into itself using a handwavium field. The reason why the field has to be handwavium is because typically force fields and other energy shields tend to let light through otherwise they look opaque and [rather boring](http://tvtropes.org/pmwiki/pmwiki.php/Main/RuleOfCool). So the field would have to let light through so the blade has the cool glow to it, but still contain the large amounts of light/laser that is bouncing around in the blade. ### Plasma Many lightsaber explanations I have seen fall under this category. Handle shoots out a hot stream of plasma, and an energy shield reflects it back towards the handle creating a fountain like effect. The plasma keeps circulating over the length of the blade, and as long as it is not slicing things it is using minimal energy. The shield does not allow energy to pass through it, but solid matter can. As a result it reflects energy bolts from blasters, and prevents other energy shields like other lightsabers from passing through them. ### Electric Start with a taser that produces a small electric arc and take it up to 11. Using a field of some kind to override the behavior of electricity it forces an electric arc to form a tall arc before coming back to the handle. Anything that gets in the way of the arc gets cooked. ### Chemical Think blow torch. Using a tank of pressurized highly volatile fluid or gas it creates a long narrow flame. The reach is normally limited, but with a sci-fi setting it could be made to have a longer flame. Since it requires a tank of fuel it is not really a practical weapon, but it is something that we do have in the real world. [Answer] If you assume your series has Warp Drive or other similar space-time manipulation; the general way these "engines" work is by changing space-time in front of them to "suck" the ship forward; essentially moving space around them. So what does this have to do with a saber? You could have a "Warp sword" which manipulates the space around it, allowing it to pass through a distorted version of the object. The distorted space can essentially shrink the sword relative to the thing it is slicing, allowing it to effortlessly cleave through the material because the blade could be (essentially) subatomic relative to the thing its cutting. Why does it glow? Maybe it's never "off", so the light in the area around it is being distorted. Why is it short ranged? Maybe the warp engine only allows for that rough distance of manipulation. NOTE: I'm not sure what happens if two warp swords hit eachother, but one could hand-wave that they each are in the same dimensionality of space; making them hit eachother like normal swords. Also NOTE: These will not deflect bullets, blasts, etc very well, but will do everything else better than a light saber. EDIT: sorry for the extreme necro. I got messed up by the side panel.. ]
[Question] [ I'm building a Dyson sphere - a real one, like Freeman Dyson originally proposed, made of swarms of solar collectors in independent orbits that fully surround the star, something like this: [![Dyson Swarm](https://i.stack.imgur.com/F1lXD.jpg)](https://i.stack.imgur.com/F1lXD.jpg) Each collector/habitat will be a truncated triangle, approximately two million kilometers wide by one million high. The inner face of some of the collectors will be inhabited, while others - those further in, exposed to stellar radiation at all times - will be entirely automated. I'm designing a society to live on one of the habitable plates of the swarm. Being further out, their plate spends most of its time shadowed by other plates, and is only occasionally exposed to the sun. The people of the plate have lost a lot of their advanced knowledge, and they see the star as their life-giving god, the plates closer to it as their heavens, the plates further away as hells. What I'm trying to work out is exactly how often would they get starlight at different levels of the swarm? How many levels have to be 'above' them for them to get, say 25% sun? Is this something that can be easily calculated, or if not is there an engine or similar I could use to find a result? Edited to Add: Detail I neglected to include originally - the closest plates to the star are about 0.5 AU out, and there's around 2 million kilometers separation between each layer of plates. [Answer] Just do surface area questions. For any given shell, calculate the area of all of the plates within that shell, and calculate the total surface area of a sphere at that distance from the star. Dividing those will give you the fraction of the time one can expect plates in that shell to shadow shells further out. This should be a more than reasonable estimate. It is plausible that some pairs of distances exhibit harmonics that result in different behaviors, but the basic probabilistic approach should be more than sufficient. [Answer] Honestly, this kinda depends on a lot of factors: Size of the plates, distance from the star, orbital period, to name a very few. The suns surface is 12,000 times bigger than Earths, meaning if each plate had the same surface area as the entire planet, you'd need 12,000 of them to cover it. If you have the plates set 1 AU out, that number gets exponentially bigger. Even at 1 earth surface area, each plate is going to be insignificant, and even a string of them isn't going to block much light unless the layers are pretty close together. so a big question is, does having the actual orbital mechanics matter, vs just saying that the cloud of plates blocks out most of the light? [Answer] Some napkin math: Assume there are n habitats each with area $A\_i, 0<i \le n $ and distance from the center of the sun $R\_i$, which are infinitely thin, with totally random orbits at distinct distances. Surface area of the sphere at distance r is defined by the shell $4πr^2$, ($r$ is distance from surface + 695700 km) Then habitat $i$ is occluded by $\prod\_{k=0}^{i-1} 1-(A\_k/4πR\_k^2)$ If $A\_k = 2e12$ for all k, and the nearest habitat is 2m km from the center of the sun, and the rest are distributed at fixed intervals of 5000 km then see [wolfram alpha](https://www.wolframalpha.com/input/?i=product&rawformassumption=%7B%22F%22,%20%22Product%22,%20%22prodfunction%22%7D%20-%3E%221-(2e12%2F(4%CF%80((2000000%20%2B%205000*k)%5E2)))%22&rawformassumption=%7B%22F%22,%20%22Product%22,%20%22prodvariable%22%7D%20-%3E%22k%22&rawformassumption=%7B%22F%22,%20%22Product%22,%20%22prodlowerlimit%22%7D%20-%3E%221%22&rawformassumption=%7B%22F%22,%20%22Product%22,%20%22produpperlimit%22%7D%20-%3E%2238%22&rawformassumption=%7B%22C%22,%20%22product%22%7D%20-%3E%20%7B%22Calculator%22%7D). $A\_k$ could also be the total surface area of all habitats at a certain distance from the sun. Of course a more sophisticated orbital scheme could be devised (this setup implies a chaotic strobe light effect) but I'd expect any race capable of engineering a dyson swarm not to use natural sunlight and instead collect the radiation and use it in a more controlled way. Inner layers radiate waste heat which is usable as energy for outer layers. I'd also not expect them to actually be instantiated as planet-optimized life. If that is the goal, a ring-world esque construct (or swarm with 1 shell at earth-like distance from the sun) makes more sense. Wide variation in distance gives you a wide variation in temperatures. [Answer] As AndyD273 stated, there are many factors to consider. Having elements shield each others is very inefficient, that's why most Dyson swarms feature [statites](https://en.wikipedia.org/wiki/Statite), they do not cast shadows onto each others and can collect light from the entire surface of the star. If you want to stick with orbiting elements then you must design orbits that lie on different "planes" each perpendicular to at least other two, [like this](http://webspace.webring.com/people/uz/zahde/BraidedWheel/RitualSphere.jpg). In this way it doesn't really matter how distant your habitat is from the star or how large the elements are, the number of yearly "nights" is equal to twice the number of orbits that lie closer to the star than yours. So if your habitat lies on the second closer orbit from the star they will experience two very short nights every "year" (orbit); if they are on the third closer orbit they will have 4 nights, on the fourth 6 nights and so on. Nights are equally sparsed throughout the year, so if a year is 200 days and your habitat is on the third orbit they will experience 4 nights a year each every 50 days. The nights all last the same time and are probably very short; their duration depends on orbital velocity. Consider that if you want artificial gravity you will need to spin your habitat unless it is massive enough to have its own gravity (this would create additional day/night cycles). Statite elements, on the other hand, don't need to spin to have gravity even if they are not massive enough, but you need to live on the dark side. [Answer] It is enough just one plate of the same size which at an orbit closer to the sun to block those people from sunlight completely. To dim light to 25% of possible light, sphere below them should be about 75% covered by other plates. Truncated triangle, let say a Rectangle 1 by 2 million km, it is about 101'250 of such rectangles below to cover 75% of 1 a.u. sphere. ]
[Question] [ Would it be easier to build Skyscrapers on a planet with 50% of Earth's gravity, and the same atmospheric pressure of the Earth. I noticed someone asked why the planet has lower gravity, this is because the planet is smaller than Earth and less dense. I'll leave some details about the planet below. * 0.282 (M⊕) * 0.50 G * 9564 km (diameter) [Answer] Yes. About 50% easier. Or, about the same, if you build them twice as high. A big factor in modern building design is withstanding the weather, so another question arises, is your planet stormy or tranquil? Is the atmospheric pressure similar, or also 50%? This'll have a big influence on the buildings, maybe moreso than gravity. [Answer] No, not with current technology. Modern skyscrapers are limited by logistical factors, such as concrete drying on the way up to the top of the building. In terms of structural stability, we could build buildings 2 miles high. But raising this to 4 miles doesn't make a difference, many other factors prevent us from reaching this height first. Edit: yes, you could build the skyscrapers with less material, and you could make them skinnier. Elevators would use less power. It would definitely make things easier, but you can't just assume that everything doubles. [Answer] It would be much easier, as there is much less downward force. You could also build some wacky stuff... ]
[Question] [ First of all, I'd like to make a disclaimer, and that is that I'm in a brainstorming phase as of now so this question will be generally vague. This also means that any ideas you're willing to propose are very welcome. Consider this as a semi-blank canvas Now, I'm currently working on a planet very similar to Earth (which I'll just call Planet X for convenience): same day & year length, is in the Goldilocks zone of its host star etc. Life on Planet X evolved much like on Earth and the sapient humanoid species inhabiting it possesses a level of technology very similar to ours. Suddenly, something happens that makes the temperature rapidly rise to unsustainable levels forcing these humanoids to live underground. What I'm looking for is a way to make Planet X rapidly turn into a scorching wasteland, and by rapidly I mean preferably in less than a century. So far I thought of the following method: somehow the orbit is altered, becoming more eccentric, causing the planet to get dangerously close to its star during perihelion. If possible, I'd like to make it so that their winter isn't colder than our springs or falls at best (a medium temperature of 23-ish degrees celsius at least on the equator would be ideal) while their summers are a true scorching hell (I was thinking something along the lines of 100-130 degrees celsius at least on the equator). Let's assume Planet X has an extremely negligible axial tilt as well, almost non existant If we went for this approach... 1) What could possibly make Planet X's orbit more eccentric in such a short timespan (less than a century)? 2) Since X would get very close to its star during perihelion, would the surface become heavily irradiated? If yes, could not only the surface but also the underground become radioactive? If yes, up to what depths? 3) In the unlikely case radiation wouldn't be a problem, would these humanoids be able to even live on the surface during this spring-temperated winter I mentioned earlier with no side effects? 4) Would at least the poles of an Earth-analog withstanding such heat be spared from desertification even during or after summers with peak temperatures of 130 degrees celsius on the equator? If you deem the temperatures I proposed too extreme, feel free to adjust them in a way you think it'd work better Alternatively, for Planet X to rapidly become a scorching wasteland we could make it orbit a red dwarf. I heard they're unstable stars that can emit unpredictable bursts of energy but I don't like the tidal lock thing and would like to avoid it... I would like your input on this as well. That is if you don't mind of course! That should be all, I think. Feel free to propose other ways to make an Eart-analog turn into a scorching wasteland or to let me know of things I might haven't considered that you think I should be aware of. I'm all ears [Answer] If you want to turn a planet into scorching wasteland without killing all the humans on it, a sudden orbital change is not what you would want to invest in. Orbital changes of the severity you have mentioned, will wipe out almost all life on the planet probably within a year or so. Considering that getting closer to the host star would mean geometrically greater amount of solar wind, the atmosphere would be swept off quickly (as in, the effects would be felt within a couple of decades) and the destruction of almost all occupations (as the surface is rendered inhospitable) would create government collapse all over the globe, leading to a very quick and violent end of the human (or humanoid) race(s). The strategy I would suggest for your desired scenario is [runaway global warming](https://en.wikipedia.org/wiki/Runaway_climate_change). Once the temperature of a planet reaches a certain tipping point (depending on the environment of the planet), it would start a cycle where more of the sunlight is absorbed, causing the atmosphere to heat up more, releasing more of the greenhouse agent, absorbing yet more sunlight and so on, until all of the greenhouse agent has been released and a new stable temperature has been reached. The greenhouse agents worth considering for triggering the effect would be methane and sulfur dioxide. While carbon dioxide is good at absorbing and retaining heat, it is no match for monsters like methane and sulfur dioxide. Once the tipping point temperature is reached, the evaporation from oceans will increase uncontrollably, leading to an ever increasing amount of water vapor in the atmosphere ... and water vapor is the monster when it comes to greenhouse effect. Once this point is reached, the oceans will boil away, rendering Earth a blistering hot, dead planet. And as Frostfyre has specified, forget any complex life for temperatures above 80 °C. Humans would already go extinct once the global temperatures reach or exceed 55 °C. The swift change would not allow for constructing underground habitations as a lot of the people involved in designing and managing the construction process would be already killed by the heat. Also, humans forced to live without sunlight for extended periods of time get emaciated and slowly waste away. [Answer] I hate to be cynical, but the easiest way is for us to continue what we are already doing: [![enter image description here](https://i.stack.imgur.com/EQc8f.png)](https://i.stack.imgur.com/EQc8f.png) in this image, the dotted line is the temperature trend and the central line is the 1960's temperature average, with every other straight line being a degree Celsius difference Just keep burning coal and we will kill all plants and animals, then you have your barren wasteland Source: <http://xkcd.com/1732/> [Answer] [![enter image description here](https://i.stack.imgur.com/jnzoB.jpg)](https://i.stack.imgur.com/jnzoB.jpg)Billiard balls solve the problem quickly. The cosmos is filled (meaning not completely missing) with high speed hunks of rock. You hit the planet with a rock. With a big rock, you can have a catastrophic effect on the rotational speed of the planet. A 300 hour day would give you scorching deserts followed by frozen nights. You might get a migratory bird swarm across the evening terminator, riding the (22K/300) 220 mph winds in the habitable bands and trying to eat bugs. You might a few survivors hunkering down between the extremes and generating power for the differential. Still, no longer prime real estate. Alternately, you can pick a number of other billiard balls for faster or slower death. Something small, fast, and dense could open a tectonic rift causing endless earthquakes, the slow loss of land, and a moderate speed release of carbon into the atmosphere. You could posit a bell-ringing shock that releases undersea or underground carbon reserves, e.g., the 'super-frak effect'. Runaway processes then take the planet to the new equilibrium. Moving from billiard balls, a voracious mono-culture flora or fauna could take over. All the pollinators could die. Some toxic substance could kill the current flora and fauna. Endless storms. Solar flares. Passing through a protostar. Low gravity allowing vapor to escape. Aliens steal the oceans. Loss of magnetic poles. Muppets. It is a lot harder to save or terraform a planet than to destroy one. All suggestions for fictional planets only. Not be used on inhabited planets. Attempts to terraform is a federal crime in the United States and areas under United Nations jurisdiction. [Answer] The Earthlike planet is orbiting a primary star with higher mass. Probably, a F6 star as that will "age" faster than our Sun with its temperature rising to levels that the ambient stellar radiation (what we call sunlight here On Earth) will scorch your planet. This will be part of the star's natural development. A F6 star reaches the end of its road in 4.5 billion years. This is the same amount of time for life to evolve on planet Earth and produce the human species. Assume your planet follows exactly the same evolutionary history and its humans will suffer the fate of a scorching planet. An alternative is that, roughly, one million years ago a small black hole fell into the Sun. Assuming that the black hole doesn't consume the Sun, but accelerating its fusion reactions to a huge extent. It takes on the order of one million years for energy produced at the centre of the Sun to reach the photosphere where it is radiated out into space. The sudden rise in solar radiation will produce a scorched Earth. [Answer] The shortest and most plausible answer is wait about 500 million years. The sun, as it undergoes its natural evolution is gradually getting brighter and hotter as the hydrogen fuses in the core and is converted to helium. In about 500 million years the increase in solar energy should have raised the temperature to the point that CO2 extraction by weathering and calcium carbonate formation grossly exceeds natural carbon replacement in the carbon cycle and most plants become extinct. One Billion years in the future, Solar luminosity should have increased to the point that the stratosphere becomes saturated with water, and solar radiation rapidly brakes the water into Hydrogen and Oxygen. The Hydrogen rapidly escapes into space and the Earth dries out in a few million years. For the purposes of your story, the planet could simply have developed complex life much later in history. On Earth, life was pretty much confined to "pond scum" for 3.5 billion years, with complex life only appearing about 500 million years ago during the "Cambrian Explosion". Why this happened and why at that particular time is hotly debated, so almost any sort of handwave on your part should be acceptable. In other words, your planet is Earth 500 million or more years from now, but the "Cambrian Explosion" is happening today. Radically changing the eccentricity of a planetary orbit is difficult. The Atomic Rockets "[Boom Table](http://www.projectrho.com/public_html/rocket/usefultables.php)" tells us the Earth's rotation energy is 2.1 X 10^21J and the orbital energy of the planet can be calculated [here](https://en.wikipedia.org/wiki/Specific_orbital_energy), which if I did it right is also @ 2 X 10^29J. As you can see, it would take a literally astronomical event to pull off. Of course, this would be of such a scale (like a neutron star entering the Solar System) that a lot of other unpleasant events would happen, such as other planets becoming destabilized in their orbits, streams of comets entering the inner solar system due to the gravitational effects of the Neutron star destabilizing cometary orbits in the Oort cloud, the possibility of comet and asteroid strikes on the planet or even massive solar events such as flares and coronal discharges from the Sun itself. I haven't even factored in events like radiation from the Neutron star possibly sterilizing the planet or stripping away the ozone layer, since that is particular to the scenario. The only other astronomical events with similar power and time scales might be the arrival of a rogue giant planet (Jupiter sized or greater), brown dwarf star or micro black hole, but in all these cases, like the neutron star, the object would have to be moving at incredible velocity through the Solar system to cause the change in a matter of centuries or a single century as you wanted. More exotic events like the passage of a cosmic string might make the event more localized, although even exotica like that might have unusual or disastrous secondary consequences (the intensity of the gravitational field might induce undesirable tidal events if it passed close to the Earth, for example). [Answer] The problem with all of the answers I've seen thus far is that heating up the planet means the climate will be wetter, not drier. Hotter temperatures means faster evaporation, but that water doesn't stay in the atmosphere forever. It all comes down as precipitation. Hotter temperatures makes for more jungles, not more deserts. Ice ages make for larger deserts. Until, that is, you reach a sufficient temperature to cause a run away greenhouse effect wherein 100% of the surface water evaporates/boils into the atmosphere. This is a run-away effect because water vapor is a greenhouse gas. There is no stable point where the oceans are just like, half the size they are today. Once this process begins, you inevitably end up with another Venus-like world with surface temperatures too hot for any surface water. There will be no oxygen and no humans. [Answer] Hmm. We have to do something... * Orbital Hijinks: I don't like this, because I don't have a nice, gentle way of moving the planet just far enough, that fast. * Star Hijinks: I like this. Your star can "heat up" just bit. Hard to justify the rapidity, but you might be able to get away with it. * Global Warming Hijinks: Don't like this, because the planet is obviously survivable after burning all fossil fuel. Why? Because that's how hot it was before that planet's Carboniferous period. Here's a new one... Let's imagine that the new unpleasant climate is what the climate should have been all along. But the planet had been going through an unnatural cold regime for a million years or so. Why? Because the sun and planet were traveling through a nebula, and the gases and particulates were blocking a certain amount of sunlight away from the planet! Once the trajectory of the solar system takes it away from all that awful space junk, the sunlight starts hitting the planet like a hammer. [Answer] The star has a companion. The companion is a brown dwarf in a very elliptical orbit. It's orbit got slightly jostled when it was out near apoapsis (since the period is so long the actual change can be a few meters per second) and this pushed it's periapsis too low--this time around it's grazing the main star. Alternately, a comet that is very heavy in CO2 comes flying by. It passes within the Roche limit of the next planet out and is turned into rubble (think of what happened to Shoemaker-Levy 9, just to a much greater degree as the approach was much closer.) This collection of rubble hits the Earth-analogue. Since it's all broken up it burns up in the atmosphere--but dumps a ton of heat and adds a whole bunch of CO2--instant greenhouse. ]
[Question] [ Evil Wizard got his hands on a Handwavium Wand, and wished the Earth's magnetic field no more. Now the surface is vulnerable to solar wind, solar radiation and cosmic radiation. How long will it be till life is gone on the planet (land) surface? Bonus points if you state how long till the oceans are also void of life. [Answer] ## Atmosphere Blowing Away NASA estimate for Mars atmosphere stripping by solar wind: <http://www.nasa.gov/press-release/nasa-mission-reveals-speed-of-solar-wind-stripping-martian-atmosphere> about 100 grams/second Earth is closer to the sun than Mars, so assuming a inverse square relation the solar wind would be about 2.5x stronger at Earth, Also earth's atmosphere is denser (160x) making a better target, but Earth has a higher gravity (3x) so my estimate would be for Earth to lose ~5 kg/s of atmosphere or 432,000 kg a day. Earth's atmosphere is 5.15×10^18 kg So at that rate of depletion the atmosphere would be gone in ~33 million years. Of course some of the oceans gases would also start to evaporate at lower pressure and as the atmosphere decreased the rate would decrease so it would actually likely be longer, but as far as planets go that's pretty soon. ## Increased Radiation The big danger here is that the solar wind would blow away the ozone layer, which block ~98% of the medium-frequency ultraviolet light emitted by the sun, but as above it would not be instantaneous, and the rest of the atmosphere would continue to filter some of the UV radiation. <https://en.wikipedia.org/wiki/Ozone_depletion#Consequences_of_ozone_layer_depletion> This would be bad, but unlikely a total extinction level event, greatly increased levels of skin cancers in humans and animals (easily +100x), and widespread biological damage with likely extinction of UV sensitive species (specifically bacteria). A lot of species have already evolved UV defense mechanisms, things like melanin, and actually actively use UV to produce vitamin D. With the increased UV levels life would adapt, humans may not survive the various collapses of ecologies, but life definitely would survive it. [Answer] Never is the answer you are looking for. Animals and plants will go extinct after a while, but I would say much later than what Josh calculated. However, extremophiles will keep on living. Some of them do not need air and get the energy from the hot vents. They will survive for a very long while. Also, humans would probably survive that event too. Building underground shelters, artificially creating habitats, using earth's heat as power source, we will grow plants underground using growing lights. Rooting out humanity is not that easy. [Answer] The magnetic fields have effectively disappeared many times in the past (during periods of magnetic field reversal). This has not correlated with extinction events, so I see no reason to think it would be dangerous at all. <https://en.wikipedia.org/wiki/Geomagnetic_reversal> Also, the current magnetic field funnels charged particles down onto the poles, yet the animals living at the poles seem unaffected. ]
[Question] [ Or have we reached the limit of what we can do with kinetic energy weapons without resorting to, for instance, electromagnetic propulsion? Futuristic settings usually depict chemically-powered weapons, when they are depicted at all, as being "bigger" (higher muzzle velocities or muzzle energies), and therefore "better". But is this realistic? Does making a bullet faster or more powerful than the weapons available today yield any tactical advantage whatsoever? More importantly, is it even possible? Or have we reached the limits of the speeds and energy levels attainable with ordinary chemical propellants? At the core of this is the question, "Are tomorrow's weapons more likely to become stronger or more exotic?", which is a somewhat different topic. [Answer] I completely disagree with most of the other answers. I believe future chemical weapons will be larger and more powerful for a very simple reason: they will have to be. Over the course of human history there has always been a "sword versus shield" balance that has tilted one way or another. The basic question: "does the standard weaponry of the day easily overcome the standard defenses most warriors will have?" is how you decide where you are on that spectrum. If technology has tilted one way and your enemy doesn't realize it yet, you can do some serious damage before he figures out what happened. Examples: Thermopylae. Spartans knew that the standard defenses of the day (Hoplon/Greek style shield) easily overcame standard weapons of the day. They had a force totally optimized around a small group of elite warriors who are not easy to kill but which required significant money and time investment to field (hence smaller in number). The Persians had a massive army consisting of cheap cannon fodder including conscripted slaves. They were using the opposite paradigm. They "won" but at such a cost that it was a strategic loss. The balance has shifted back and forth for centuries. In times when weapon lethality is dominant, large armies of cannon fodder are the way to go, in times when defenses are dominant, small armies of professional warriors dominate. In medieval times, defensive technology had outstripped weapon lethality oncve again. Crusaders encountered armies many times their size and prevailed in many cases. Many accounts wrote of knights returning from battle covered in arrows like a porcupine, but with no major injuries. It was logistics that really stopped the crusaders of the earlier crusades, not technology or battles. The pendulum came back with gunpowder. Armies organized around a small group of professional elites with good defensive technology were swept aside, but it took a while before someone really organized for optimum performance in the gunpowder era. If you look at Napoleon, it wasn't just that he was a good tactical commander, but what you have to understand is the revolutionary way that France had been totally transformed into a machine for churning out massive armies of cheap cannon fodder. Napoleon could crank out MULTIPLE 300,000+ man armies after burning through them one after another while his enemies struggled to keep one or two forces of that scale in the field. How? He basically created the modern nation state; a machine designed around the draft, which would efficiently crank out expendable soldiers capable of standing in a line and using very simple weapons, marching, and dying on command. I won't go through WWI, WWII, The American Civil War, etc, but we have CLEARLY been in a "lethality" paradigm for a while now. WWII was almost completely a war of attrition. What is interesting is that today we are undergoing a revolution in materials technology. Ceramic plates capable of stopping a machine gun round are normal for our military. That is totally revolutionary, and it turns Napoleon's paradigm on it's head. We can now make a warrior totally bulletproof. The only limitation is the weight of the armor. That puts us back somewhere between the Spartans and the European knights, which means that smaller, more professional, more skilled, and more expensive militaries will prevail (and we see this trend increasing, just compare WWII, Vietnam, Desert Storm, and the recent war in Iraq). Soon, the dominant paradigm will be VERY elite and professional lifelong warriors wearing 100% complete bulletproof armor suits and operating very complicated and high tech weapons, at a very high cost per warrior (so there will be few of them). In this environment chemical weapons will have to get more lethal (as melee weapons did all through the middle ages as engineers sought to penetrate ever better armor). How? Given the limitations of chemical propellants already mentioned, think about some options: 1 If we solve the "armor weight" issue using some sort of robotic exoskeleton (as the US Army is currently working on) we have also allowed an infantryman to carry something closer to a .50 cal machine gun. We have also created a need for him to have more firepower since his opponents will probably be "bulletproof" to a typical light round like the .225 currently considered NATO standard. 2 Chemical propellants might have maximum expansion velocities, but we have already figured out how to optimize the technology in a few ways that aren't cost effective for a "cannon fodder" army but will be used in the new paradigm era. DU rounds drastically increase the mass of the bullet and thus it's ability to carry kinetic energy to target. As a side benefit, they also create burning gas sometimes, which increases lethality. 3 Discarding sabot ammunition minimizes the drag on a projectile while maximizing the power of your propellant. This is the direction "infantry" weapons will probably take as warriors have to overcome one another's ever better armor in years to come. 4 Rocket assisted ammunition can continue to accelerate after it has left the weapon. Advanced designs include the ability to mix and match rocket assisted and "conventional" ammunition in the same weapon. 5 Advanced "supergun" concepts designed to launch satellites have experimented with multiple, sequential firing chambers. Chamber one cooks off, bullet moves down the barrel, at a certain point, chamber 2 (halfway down the barrel) cooks off, and bullet gets even more energy. This could be miniaturized. 6 Explosive payloads can be integrated into larger caliber infantry weapons as a standard feature (once again, to overcome armor). Think miniaturized HEAT rounds (High Explosive Anti Tank) that form a plasma "jet" when the round comes into proximity with the target's armor. 7 Some nice new concepts like "metal storm" -electrically initiated conventional chemical projectiles and helical ammunition storage promise to radically increase the firing rate and ammunition storage possibilities of small arms. Most of this stuff is already being done at the scale of vehicle weapons, tanks, etc. The difference is; as infantry get more armor, they are also going to start adapting these sorts of tactics to OVERCOME that same armor. This is already happening today. Unless there is a major technological sea change, expect the future to be more "starship troopers" (the book, not the idiotic movie) and less "red badge of glory". [Answer] Short answer: Not really. Longer answer: There's basically no chance of a revolutionary redesign of weaponry that'll give you higher muzzle velocities. Why? Because the maximum speed the propellant (the exploding gas in the barrel) can travel [is tied to the speed of sound of the working fluid](https://en.wikipedia.org/wiki/Light-gas_gun#Design_physics). To shoot a projectile faster, you need to swap to a substance with a higher speed of sound. The gas with the highest speed of sound is [Hydrogen](https://pages.mtu.edu/%7Esuits/SpeedofSoundOther.html). There's already a proposed Hydrogen cannon for [launching satellites into space](https://en.wikipedia.org/wiki/Quicklaunch). This is the most exotic change I can think of, and even then it's just a simple case of engineering the cannon down to hand-held sizes. We use gunpowder today because it's good enough, and can be safely and conveniently carried about. That's not the case with Hydrogen. [Answer] Higher muzzle velocity or heavier bullet would mean stronger recoil. We already are at the limit. I'm a big guy, and I had trouble holding good old Colt. Professionals can use guns bit stronger, but there is only so much your hands can take. See [this article](http://www.maxim.com/gear/10-most-powerful-handguns-planet) to see how strong guns can get. And video at the end shows what happens when recoil is too strong. Anti recoil mechanisms are complicated. They aren't popular in common guns. Patents were filled (<https://www.google.com/patents/US7343844> <https://www.google.com/patents/US3483648> <https://www.google.com/patents/US7231944> etc) but apparently didn't get much market. And [recoilless riffle](https://en.m.wikipedia.org/wiki/Recoilless_rifle) is not practical for a hand gun - hot gases in the face are not acceptable. The only way to make "bigger" acceptable in a hand gun would be to make recoilless acceptable: cheap, reliable, and light. TL;DR Recoil. We don't want higher energies. [Answer] The weapons of the future are in fact likely to become less lethal, more targeted, and less oriented toward killing, but more closely linked with information (tracking hostiles), capturing hostiles and controlling them. This projection is in line with actual historical trends in reductions in violence while modernization and global connectivity progress across the globe. <http://www.scientificamerican.com/article/history-and-the-decline-of-human-violence/> --- ### Long Answer It is concievable with some *very* sophisticated technology that the projectiles of future weapons could be formed merely of energy or operate based on stranger phenomena, perhaps travelling at close to light speeds. Consider how the Earths magnetic field [deflects solar ejecta](https://en.wikipedia.org/wiki/Earth%27s_magnetic_field#/media/File:Magnetosphere_Levels.svg) and small, charged high-speed particles. In a similar fashion, a projectile which generates a very strong field, or a "node" projected in front of a projectile from the source location of the weapon, which operates on the same principles as an [ultrasound tactile display](https://www.youtube.com/watch?v=hSf2-jm0SsQ), could be used to ionize and disperse matter in front of the projectile as it travels. This has the effect of providing the energy taken away from the projectile in the form of drag as it moves through the air or whichever substance presents a frictional barrier to reaching the target. Granted, this is all very hand wavy and impractical, but one day that may not be the case. Advantages to this? Your guess is as good as mine, but presumably, the increase in speed would level the playing field. In current warfare, with long range tracking, radar and visual, long range observation, we can detect the firing of weapons moments before impact, providing valuable lead time when the projectile is targeted at the observer. Faster moving projectiles, close to the speed of light for example, would have a velocity curve that does not decay and so lead time would be minimized to the point where the firing of the weapon and any signal that a weapon has fired would arrive at approximately the same time. ]
[Question] [ What's the best current material for making something like [Captain America's shield](https://en.wikipedia.org/wiki/Captain_America%27s_shield)? Important Properties: * Strong enough to withstand (almost) all physical hits and bullet fire * Light enough to be thrown like a frisbee (by someone with a lot of strength?) * Bonus: Is magnetic I assume there's no material in existence that has the above properties, but is there something that is strong enough to withstand a reasonable amount of force while still able to be thrown by someone with incredible (within human limits) strength? [Answer] You're Looking for a Shield-Sized Trauma Plate When considering the basic requirement - being bullet proof - I think the best thing we can do is find a good Trauma Plate and scale its size up. Ceramic trauma plates are very good, but are not normally re-used because they tend to crack or develop micro-fissures that could lead towards catastrophic failure after another impact. When re-use is a consideration, Steel or Titanium are the most used metals. Regarding Weight This is where I think titanium is going to really run away. [This link](https://www.wired.com/2014/03/whats-mass-captain-americas-shield/) gives the volume of the shield of between 0.00227 – 0.00454 m3. We also know the density of steel (~8,050 kg/m3) and titanium (~4500 kg/m3). That would mean a steel shield would weigh between 18.27 and 36.547kg (40.2 - 80.4lbs). A titanium shield would weigh between 10.215 and 20.43kg (22.5 - 40.9lbs). NOTE however that the shield weight is calculated based on Captain America's shield. It's likely that many types of gunfire could rip through the shield at that thickness using real materials. So let's assume that we are stopping only small munitions fire. Otherwise you need to start multiplying the weight considerably, and even a 2x factor is enough to make the entire endeavor utterly impractical. Throw Distance Looking at throwing distance, let's consider the closest analogue we have for throwing really weighty things... the "weight throw" event of track and field. Women use a 20lb ball , which is analogous to the lowest end of the titanium weight scale. The record in that category is [24 meters](https://en.wikipedia.org/wiki/Weight_throw) (around 79 feet). Men use a 35lb ball - lighter than the steel shield but within bounds for titanium - and the world record is 25.8m (~78 feet). Mind you, in "weight toss" you get a run up and a more ergonomic handle to launch with than you would find in a shield. My estimate is you could probably halve those numbers at best for heavy shield tossing. Magnetism (as requested) Steel can be magnetic or not, depending on how it was produced. Titanium is generally nonmagnetic, to the point that a patient with titanium implants can be scanned by an MRI safely. [Answer] [@GrinningX](https://worldbuilding.stackexchange.com/a/55097/760) is on the right track. I'll add detail based on existing bulletproof materials and standards. # The Requirements What you're looking for is [NIJ Level IV protection](https://justnet.org/pdf/Understanding-Armor-Protection.pdf). Level III will stop a [7.62mm rifle round such as fired from an AK-47](https://en.wikipedia.org/wiki/7.62%C3%9739mm). With about 2000J of energy it's the most powerful bullet Cap is likely to encounter on a modern battlefield. But Captain America's shield was for WWII. Bullets were a lot more powerful back then. He'd be facing things like [.30-06 Springfield](https://en.wikipedia.org/wiki/.30-06_Springfield) used by the US in WWII or [7.92 x 57mm Mauser](https://en.wikipedia.org/wiki/7.92%C3%9757mm_Mauser) used by the Germans. These are in the 4000J energy range. For that you need Level IV protection. [![enter image description here](https://i.stack.imgur.com/uyBJN.jpg)](https://i.stack.imgur.com/uyBJN.jpg) [Then there's the V0 rating](https://en.wikipedia.org/wiki/Bulletproof_vest#Ballistic_testing_V50_and_V0), the most energy a bullet can have and never penetrate. For example, if we say Cap's shield has a V0 for .30-06 then it means you can fire .30-06 at it all day and none will penetrate. This is a tall order. Each high energy impact will make small bends and cracks in armor and they will add up. The more realistic measure is the V50 rating, the most energy a bullet can have an only penetrate 50% of the time. 50% doesn't sound like great odds when it's your chest on the line, and nothing about Captain America is 50%. Most body armor is made up of layers to absorb and distribute the shock of impact, a combination of soft armor like Kevlar and hard armor like steel and titanium, all backed up by your squishy flesh. Cap's shield has none of these advantages. It acts as a "stand alone plate" meaning it will protect with nothing behind it. [![enter image description here](https://i.stack.imgur.com/WGYyT.jpg)](https://i.stack.imgur.com/WGYyT.jpg) # The Shield * A stand alone plate * Roughly [75 cm in diameter](http://marvel.wikia.com/wiki/Captain_America%27s_Shield) + Roughly [4600 cm2](http://www.wolframalpha.com/input/?i=area+of+a+2.5+foot+diameter+circle) * Providing Level IV protection * With a V0 at .30-06 * And throwable by an Olympian This is a tall order. [The lightest stand alone level IV plates I've looked at weigh about 4 to 5g per cm2](http://internationalbodyarmor.com/10x12-ultra-lite-ceramic-hard-armor-rifle-plate-stand-alone/). That means a 4600 cm2 shield will weigh 18 to 23 kg, significantly more than [the comic's 5.5 kg](http://marvel.wikia.com/wiki/Captain_America%27s_Shield). Worse, these are ceramic and only guaranteed to stop ONE level IV shot. Captain America cannot have his shield shatter after one shot. This isn't going to work. # Lowering Expectations In order to make this work we're going to have to lower our requirement to level III and ease up on the V0 requirement. Sorry Cap, you'll have to hope the Germans have [submachine guns](https://en.wikipedia.org/wiki/9%C3%9719mm_Parabellum) and [StG 44 assault rifles](https://en.wikipedia.org/wiki/7.92%C3%9733mm_Kurz) and do some ducking. Or maybe this is a modern Captain America. You can get a [titanium-steel multi-hit hard armor level III stand alone rifle plate](http://internationalbodyarmor.com/10x12-triple-curve-titanium-steel-hard-armor-rifle-plates-stand-alone/). They're about 1cm thick and still 4 to 5g/cm2. This still leaves Cap with a 20kg shield. # The Throw For comparison, [regulation Men's Discus uses a 2kg disc](https://en.wikipedia.org/wiki/Discus_throw). This shield is ten times that. [Regulation Men's Shot Put](https://en.wikipedia.org/wiki/Shot_put#Competition) is 7kg, still three times less than our shield. To get into the right scale we need to look at the Highland Games. [The heavy weight ball (on a chain) is 4 stone (25.4kg)](https://en.wikipedia.org/wiki/Weight_throw#Highland_games). Finally, we're in the ballpark. [The Irish record is 9 meters](https://web.archive.org/web/20120217194458/http://www.athleticsireland.ie/content/?page_id=4). An impressive distance in a sporting event, but not a terribly effective ranged weapon. Unless he hopes the bad guys will laugh themselves stupid as he heaves his only protection 10 yards towards them, I think Cap is better off using the shield as a shield and shooting the bad guys with a pistol. # The Ergonomics A [M240 machine gun](https://en.wikipedia.org/wiki/M240_machine_gun) weighs about 15kg loaded. It's considered very heavy (the [M249](https://en.wikipedia.org/wiki/M249_light_machine_gun) weighs 10kg). If you want to lug one around you generally do it with a sling. [![enter image description here](https://i.stack.imgur.com/E05FF.jpg)](https://i.stack.imgur.com/E05FF.jpg) It's still lighter than our shield. Cap is expected to hold something even heavier with one arm, run and jump with it, move it quickly to block shots, and swing it to clobber enemies. # Make The Shield Smaller We're not going to get any lighter material. At this point you'll have to cut down on the size of the shield and probably make it square. A more reasonable a 50 cm x 50 cm gives a 12.5 kg shield still wide enough to fully cover Cap's broad shoulders. This is still very heavy and unwieldy, but puts it in the range of a very heavy automatic weapon. There's good news for the throw. This puts it closer to [the 35 lb (15.9 kg) weight throw, the record for which is 25 meters](https://en.wikipedia.org/wiki/Weight_throw#Indoor_event). Still, that's probably at a high arc and not a graceful Frisbee, unlikely to be terribly useful in combat. It's not going to bounce back, so he's thrown away his protection. Still probably better off with a pistol. [![enter image description here](https://i.stack.imgur.com/sa7hW.jpg)](https://i.stack.imgur.com/sa7hW.jpg) ]
[Question] [ Inspired by TrEs-2b's Ant-hill species <http://meta.worldbuilding.stackexchange.com/questions/3781/what-species-are-you-currently-designing/3794#3794> As well as this question [How do I wage war against a collective consciousness?](https://worldbuilding.stackexchange.com/questions/52468/how-do-i-wage-war-against-a-collective-consciousness) Now that it is known how an ant-hill can be defeated but we do not know how do they fight! Would they gather as one giant collection of ant-hills, each with hundreds of thousands of ants, or each attacking on it's own? [Answer] A collective consciousness would be able to give instant orders and to place troops perfectly one by one, something that even a strategy games player often don't bother to do even by having the ability to pause the game. Also troops would have no hesitation to sacrifice themselves if that can be turned in a great advantage for the consciousness. Again this is depending on the fact how the collective consciousness really work. (in example instant communication to all entities, or just a behaviour that favours the collective? I assume the foremost). How do they fight? Like every army, they would place troops with weapons. Think at when SWAT breaks into a building, they already programmed that action and the criminal probably barely imagine what is going to really happen and how the troops are really moving, you see few individuals against a organized collective. When someone gets killed you know roughly the position of who killed him, and you can send immediately some soldier from more appropriate positions. Coordinating ants to dig tunnels under enemies is also a breeze and most of the army would be organized into sparse clusters with solitaire scouts exploring the surroundings. Modern armies approximate to a certain degree that concept (forts, outposts, headquarters), but then logistic coordination becomes a problem so we have to accept compromises. but a collective consciouses could do that in an almost perfect way without compromises because has no coordination problems. Guerrilla is the most effective weapon, they would just allow their enemy to enter the territory and then face the logistic consequences of that, they don't even need to kill soldiers at all, just cut supplies and sabotage in a perfectly stealth fashion and enemies don't even know how many ants are facing. Attacks would be coordinated in the moments in which troops are most vulnerable, they could retreat instantly as long as all soldiers are waken up, and attack when most of them sleep, making it really stressing and hard for soldiers. As long as soldiers get used to a certain behaviour they could change behaviour (in example if every attack is followed by a Immediate retreat, then soldiers may no longer be willing to get out of bad and every attack, and that would be the perfect moment for the final strike). Of course maybe you don't want such perfection otherwise the plot could become much more boring. [Answer] The Borg I'm not too sure about insects, but I think we could draw parallels with Gene Roddenberry's Star Trek. More specifically the Borg. A collective consciousness that encounters the Federation more times than any other opponent (Save for perhaps the Klingons). So what do we know about how they fight? Firstly - The Borg seem to have no independent thought, but are instead controlled by a hive-mind/Queen system. Each time the Borg are faced, it is generally a single cube or, if there are a significantly large number of foes, multiple cubes. (We do see a Borg Sphere that seems to contain the Queen in VOY/TNG) These cubes hold multiple Borg individuals that are active, but seem to have no notion of any job save for that they are assigned to (But that could be just because it's the silver screen) - If we infer from this that the orders the individual receives are from the Hive or the Queen; then they are absolute meaning total control. So how would they fight a war? Borg work very well as a large-number tactic. With their maneuverable ships and hit-and-run tactics they swarm enemy ships before they have a chance to retaliate, and then, to replenish any lost drones in the melee, they assimilate their opponents into the collective. The Borg also adapt rapidly to their opponents, their shielding adjusting to deflect or absorb weapon fire within a few hits and, while and insectoid army may not be as quick, there's no denying you could think up a way that such a hive mind could get around enemy fire. We can infer that, because the Hive mind has total control, there is no room for individual thought or experimentation, meaning no outside-the-box, hail-Mary plans, which leads to them seemingly being outmatched by the Federation ships. In Conclusion I think if you take inspiration from here you'd be close to what you're looking for. It's not an exact match as, the Borg are still humanoid and not insectoid, but it seems the closest relevant similarity I can think of at this time. [Answer] A) "Ancillary Justice" trilogy just won the Hugo/Nebula awards for covering exactly a collective consciousness at war with itself. Go read! :-) B) For an ant-colony like collective specifically, I think the question is best asked "how do you wrestle with your own conscience?" Your brain is a collective consciousness -- various subsystems that each contribute to an overall view of the world that gets synthesized as one. Neurons just aren't allowed to wander apart, generally, and they don't ever operate in isolation from the rest of the collective. But human minds do get divided from themselves. I would treat the ant colony at "war with itself" simply as insane... no longer doing what is needed to maintain the colony as a whole, but each ant simply not coordinating activity with the other ants. They don't even have to be particularly evil about it, just not aware of/subservient to the needs of the colony as a whole. [Answer] I also have my own idea on how they would do so. Being a big fan of the Warhammer 40.000 universe, I'll take two very different examples. On the one hand, we have the Tyranids, which are basically giants swarms of insectoids creatures obeying to the Hive Mind. Their main strategy in war is the good old mass assault tactic, sending millions after millions of small sized creatures to overrun most defences. But, it is not the only thing the Hive is using. There are some bigger creatures, used as walking tanks to destroy heavy fortifications, there are also tunneler creatures, flying ones, and all sort of things. So the mean they have on the battlefield are pretty common, the biggest difference is that these soldiers will never surrender, they will also never flee if under control. Meaning they will take enormous losses during any fight. But how could they sustain that much losses ? Mostly by quick breeding and gestation. Another interesting thing is that most of these small soldiers can't eat. They got claws and fangs and mouths but do not eat things. Thus, once the fights is over, the smaller beings come back to somekind of gastric acid pit where they'll be digested and their biomass will be sent back to a ship, ready to be used to produce new warriors once more. So, their soldiers are definitely reusables and don't have any word to say about it, apart from the bigger ones which have somekind of autonomy. The most interesting thing with them is probably how they manage to maintain a link between them. The Hive mind needs somekind of relay to reach all of its minion. These are the most important creatures in the swarm, while these creatures are present, the small minions obey without a complain and everything is alright. But once these creatures are dead, the link between the Hive and the minions is cut, thus disrupting them greatly. It's generally a good way to deal with these creature, kill every Hive Mind relay, and the swarm will be quite easier to deal with. These relay are also a strength as much as a weakness, for instance they allow some elements of the swarm to act independently, as infiltrators or assassins. The second case in that universe is the one of the Necrons. Some might argue they do not have a real collective consciousness, and they are right, nonetheless they are using a lots of robots, and their base soldiers though they were human once, are now machines which must obey to their Overlord. So for me it's quite like a collective consciousness in the fact that every Necrontyr apart from the high command will have almost no free-will and will mostly obey to any given order. While the Tyranids fights in a very bestial way, with basic strategies from a predator hunting its prey, Necrontyrs are far more evolved and tends to use the fact their soldiers are soulless, emotionless and can react at the speed of a quantum processor to build powerful strategies. Apart from the fact they master an impressive military technology (hey guys, look look we have the power to turn a star into a supernovae !) their tacticians can count on an impressive level of coordination. Even though they could gather in impressive big blocks of soldiers they tend to be organized in units, somehow inspired by the roman legion system, with centuries, cohort and legions. Taking advantage of the fact they're mostly machines, their plans are made in multiple dimensions, using complex mathematical / physical concept, to the point the only other race that can really surprise the best Necrontyr strategist are the Orks since they are so dumb and acts in such an irrational way that their moves can't be predicted by science. When facing Necrontyrs, you can count on enemy reinforcement joining the fight at the exact moment needed, and when seeing their soldiers withdrawing you can assume it's part of the overall plan. Lastly, their soldiers do not have any voice emitters or stuff like that. So they're fighting in a perfectly disturbing silence, broken only by the sound of their weapons. Afterall, why would these minions with no will need a way to communicate by voice ? I hope it'll help you creates your own Collective Consciousness and make it ready for war. ]
[Question] [ I am taking a page from the [Anatomically Correct Series](https://worldbuilding.meta.stackexchange.com/questions/2797/anatomically-correct-series) here. But instead of a living organism, I'd like to ask about a special kind of vessel. I like ships. They are big and confortable. They have rooms for crew, for loot, for cargo and for dance parties. However, they don't usually fly high in the sky. I like helicopters. They can hover in one place, they can take off vertically and they don't need strips of specially paved road orders of magnitude longer than them to land. However, they aren't really know for being spacious. What I would really like to have is an aerial ship that flies by using propellers, as we see in so many different media and styles. [![Final Fantasy IX](https://i.stack.imgur.com/BLLQE.jpg)](https://i.stack.imgur.com/BLLQE.jpg) [![It's a me, you know whom!](https://i.stack.imgur.com/ZutZ5.png)](https://i.stack.imgur.com/ZutZ5.png) [![Castle In The Sky](https://i.stack.imgur.com/Z9fhv.jpg)](https://i.stack.imgur.com/Z9fhv.jpg) [![Avengers, assemble!](https://i.stack.imgur.com/6UfT3.jpg)](https://i.stack.imgur.com/6UfT3.jpg) Why not a zeppelin, then? Because unlike a ship, a zeppelin will dedicate most of its precious volume for gas. I'd like to be space efficient here. Also I think that this more easily allows for an armored hull. Now I have a feeling that the reason we don't do this is because it's not realistic. But I have to know. Could these be done? What would we need to change? If not with our current technology, then what would we need to develop to make it possible? Also please notice that the two most closely related questions ([this](https://worldbuilding.stackexchange.com/questions/23989/airship-aircraft-carrier-dimensions) and [this](https://worldbuilding.stackexchange.com/questions/37199/airships-without-huge-balloons-gas-bags-that-can-still-float-in-air-using-min)) that I could find are about airships that require lighter-than-air gases to stay afloat. As I said before, I'd like to avoid that requirement. [Answer] There are two separate problems with this: The first is the difference between helicopters and the vessels in your pictures. The fantasy pictures show craft with lots of small rotors, largely or entirely pushing air down onto the deck of the ship. This does no good at all: the upward thrust on the rotors from pushing air downwards is mostly cancelled out by that moving air pushing down on the deck. Helicopters, in contrast, have one or two rotors that are much bigger than the body of the helicopter so most of the air goes downwards without hitting the craft. Many helicopters are also somewhat streamlined in the vertical direction, so that the down-thrust on the body is reduced. Your high-tech example picture doesn't have that problem, but its fans are fairly small, so they'll need to spin fast and move air downwards at high speed to develop enough thrust. This takes much more power than moving a large mass of air more slowly: helicopters do the latter because it's more power-efficient and they can thus carry enough fuel for a few hours of flight. And fuel, or some other source of energy, is the big problem for anything that wants to fly with rotors and stay up for days at a time. Helicopters were pretty marginal with high-powered lightweight piston engines, and only became really effective when [turboshaft](https://en.wikipedia.org/wiki/Turboshaft) engines were developed. They're still small compared to fixed-wing aircraft, can't carry much, and have limited flight duration, because they can't carry very much fuel and burn through it quickly. There's also a limit to how big you can build a helicopter rotor, because if you make it too large the tips are moving faster than sound, which is very noisy (which wastes power) and very bad for efficiency. So if you want to build a very large helicopter - which is what a ship-sized rotorcraft would be - you have to have lots of rotors on outriggers, like this [Mil V-12](https://en.wikipedia.org/wiki/Mil_V-12), only more so. This isn't absolutely impossible, but fixed-wing aircraft have been far more effective so far, and nobody has had a motive to build a super-giant helicopter. Most of the reasons why it is hard are basic physics and the properties of air, rather than a lack of technology. A magical power source that doesn't need fuel would solve flight duration problems - but would also work for fixed-wing aircraft. [Answer] Helicopters are difficult to fly, expensive, complicated and require constant maintenance. Ducted fans have efficiency problems outside ground effect. Tilt rotors have stability issues. Vector thrust turbo fans are inefficient in hover mode. Balloons are slow and don't like wind. ## However [These guys seem to have a solution (pdf).](https://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&ved=0ahUKEwiZuKj0yN7OAhVlCMAKHaVAAlMQFggqMAI&url=http%3A%2F%2Fwww.mdpi.com%2F2226-4310%2F2%2F4%2F555%2Fpdf&usg=AFQjCNFKzEtPdfaI6kDgV0ulft_l8_kudw&sig2=LQZ80Q0CNYFuThrLR-O-QQ&cad=rja) The annular ducted fan. > > The present study aimed at assessing a novel annular-ducted fan lift system for > VTOL aircraft through computational fluid dynamics (CFD) simulations. The power and > lift efficiency of the lift fan system in hover mode, the lift and drag in transition mode, > the drag and flight speed of the aircraft in cruise mode and the pneumatic coupling of the > tip turbine and jet exhaust were studied. The results show that the annular-ducted fan lift > system can have higher lift efficiency compared to the rotor of the Apache helicopter; > the smooth transition from vertical takeoff to cruise flight needs some extra forward thrust > to overcome a low peak of drag; the aircraft with the lift fan system enclosed during cruise > flight theoretically may fly faster than helicopters and tiltrotors based on aerodynamic drag > prediction, due to the elimination of rotor drag and compressibility effects on the rotor > blade tips; and pneumatic coupling of the tip turbine and jet exhaust of a 300 m/s velocity > can provide enough moment to spin the lift fan. The CFD results provide insight for future > experimental study of the annular-ducted lift fan VTOL aircraft. > > > Unfortunately (at the time the paper went to press) it's still entirely theoretical, nobody has built one to test. [Answer] Not quite an answer (I don't really know if flying boats could* be done or not based on current technology), but I felt like explaining a bit of the simple physics as to why such a thing would be difficult, and it didn't fit in the comment box so I put it here.* For the airship to be able to hover in midair, it needs to have no net force acting upon it, meaning that the downwards force of gravity has to equal the upwards force produced by the rotors. * Force = mass \* acceleration * Force \* time = momentum = mass \* velocity. The downwards force on the ship is the ship's total mass multiplied by gravity (on earth, 9.8 m/s/s). For your ship to be able to hover, that force has to be matched by the mass of output air multiplied by the speed of that output air "caught" by the rotors. To explain that a bit better, let's say that you have a 100 kg airship at sea level. (Amounting to about 1000 newtons of force due to gravity) To be able to lift off, you need to be able to match that 1000. That could be 100kg of air (about 81 cubic meters) moving down at 10 meters/second, 50kg at 20m/s, and so on. As your flying thing's mass gets bigger, the rotors need to output more power (and thus need more power fed into their rotation). While rotors work for helicopters, you can't necessarily simply scale it up to flying boats; without getting into the details (mainly because I'm not qualified to explain them), I will say that gas/fluid dynamics will start to work against you if you try to move too much air too quickly, and your rotors will fail if you spin them too fast. In case it helps, such an idea would be more practical (though still less so than airplanes) on a planet with less gravity and/or a denser atmosphere. ]
[Question] [ In the marvel universe mutants are much more fortunate than in our world; they often have extremely useful powers; ranging from telekinetic abilities to wings. As interesting and plain fun as this idea may be, it is hardly explained without using large amounts of handwaving. Using as little handwaving as possible, how can I explain the mutations in the Marvel universe? [Answer] I haven't been current on Marvel canon for many, many years, so none of what follows is based on anything but imagination. 1. The universe is significantly more complex than we think it is. Throw any law that starts with the word "Conservation" out of the picture. These not-laws were just a side effect of the scientist who came up with them not being a mutant. 2. The universe is responsive to human thought in a way that would make any quantum scientist drool with envy. Within the human brain matter (or slight variations on that design) there are circuits which can access the universe's under-structure; the building blocks with which the physical laws were written. These circuits can temporarily change the rules and then later, change them back. 3. Mutants can have varying levels of conscious control over those circuits. Mutants whose powers are interactive (like magneto) have more control. Mutants whose powers are constant (like cyclops), not so much. From there, each of the branches of power would require a thesis level dissertation to explore all of the ramifications. Professor X's telepathy requires that the nature of human thought be much more than the electrical impulses within our skulls. Nightcrawler's teleportation validates the existence of multiple dimensions. Gambit's control of probability Dr. Strange's powers... ... ... I give up! Gambit Dr. Strange breaks the universe. It just doesn't work while he is real. ... ... ... Which leads us back to our old WB standby... It is all a Virtual Reality and in this case, the programmer is a fan of marvel comic books. ... ... I tried... I really tried... [Answer] There's two routes that I would choose from 1. There are thousands/millions of either bad mutations or pretty much no difference mutations but they aren't covered in the stories. Which gives the whole anti-mutant movement a different spin and the xmen/Magneto crew only selecting positive mutants a pretty awful taste in the mouth 2. Divine/Government/Alien intervention - it's all part of a plan and there's a limited number of mutations that have been preassigned to the human race through whoever's plan we're all following [Answer] A little grim on this one...but the simplest way of explaining this is only around 1% of the mutants actually gain something beneficial. The other 99% gain something horribly inhibiting and die in the womb or shortly after. You are simply seeing the ones lucky enough to survive their mutation [Answer] ## Access to more dimensions The mutations simply allow them a limited amount of direct access to more dimensions and what we perceive as supernatural abilities is simply the spillover in our dimensions of movement in others. Imagine if you stuck your finger into [Flatland](https://en.wikipedia.org/wiki/Flatland). The Flatlanders would see a "you" in a place with a form. * If you moved your finger up and down they'd see metamorphosis. * If you took your finger out and put it in again somewhere else they'd see teleportation. * If you used your other hand to move or destroy something in the world they'd see remote kinetic effects. * If you put in several fingers they'd see duplication. * If they harm the bit they see, you merely present a different part and they see healing. [Answer] A huge problem with Marvel Mutants is not just that the mutations are useful - but that they are incredibly useful! This isn't a mutation that gives you a probability to have a slightly longer leg or a 0.01% more efficient oxygen metabolism...no, its light bending camouflage, instant healing of massive damage, fully functional telepathy. So, it seems that the theory of evolution through incremental improvement and selection is right out the window. Is there even anything in the Canon to suggest mutations breed true? So lets imagine the mutation we are dealing with IS NOT the direct cause of the effects we are seeing. RATHER, the mutants are all carriers of the same mutation. This mutation is one that enables something we will call a chimeric adaptation in humans. All the mutants are chimeras. The mutation they carry enables inclusion of whole segments of other species DNA into their human DNA. Mutants with the ability to camouflage have included cuttlefish or octopus dna sequences into their own genome. Mutants with regenerative powers have lizard DNA in thier genome. In this way, we create a device to leap over the gradual evolution and use this adaption to include new genetic features that appear to be instantly evolved fully formed in humans, but are actually the result of millions of generations of evolution in another species and have been taken, nearly whole, directly into humans. FOUL BALL! I hear you shout. There's no way that octopus genes that have adapted to work well in the presence of many other octopus genes are going to continue to function when they find themselves suddenly spliced in with a bunch of human genes. Even though we can believe there are loci in the human DNA where insertion of octopi DNA would have a beneficial effect, the odds of randomly splicing an octopus gene into that location instead of into a location where it has no effect or a detrimental effect work out to be, essentially, just as astronomical as the chance of evolving these useful adaptations in a single generation using the standard mutation model. So we need a solution that improves the odds of landing the useful octopus gene sequences into locations that will yield a beneficial human adaptation. The mechanism I propose for our chimeric adaptation is that the foreign gene sequences are actually inserted in many locations on every chromosome. It is the nature of the chimeric adaptation to provide a structure for inserting the foreign gene, for marking the start and stop of the gene, and for providing an epigenetic signaling apparatus that allows every gene insertion that proves to be deleterious to be "turned off" so that it is not read by cell protein building apparatus. Now we have greatly improved the odds of the octopus gene splicing into a useful location, because we have spliced it into millions and millions of locations. We got lucky once in a million-million tries. Many or most of or missed tries would normally be fatal mutations, but our chimeric adaptation machinery allows the effects of such bad splices to be turned off, leaving us with only our good or no effect splices still actively operating in cells. Next question - how the heck did the mutants even have the genetic material available to make these splices? Did the mothers of all mutants with a camo mutation need to be eating sushi while pregnant? I think I can propose several possible mechanisms. 1) In this world, GMO foods and other GMO products are far more widespread and much more...advanced(??). In this world, there are cosmetics that include octopus genes, and foods that include lizard genes. All for perfectly logical reasons, but the result is that humans in this world are routinely exposed to genetic material from a multitude of species. And (IMPORTANT) these are genetic sequences that have already been selected by human scientists because they do something useful. The chimeric adaptation has been present and evolving in humans for millions of years and has a useful effect in dealing with retro-viruses. It is only when this adaptation encounters the new man made environment where trans-species genes are being dumped routinely into the blood stream that this adaptation enables the new and remarkable effects we see as Marvel Comic style mutations. 2) In this world, a mimivirus exists that, as part of its life cycle, takes up and replicates gene sequences from many different species. As part of this cycle, at random times, during copying sometimes the gene previously taken up will be spliced out and another gene, from the current host, taken up. In this way, the mimivirus may act as a vehicle to copy a gene from one species, replicate many billions of times, and cary that gene sequence to many other species and individuals. And, at random times, deliver its payload of foriegn genes into a new host individual. In most cases, this foriegn genetic materials is destroyed by the host. However, in the case of a host with the human chimeric adaptation, this foriegn material is copied into the genome (per above mechanism) and becomes the possible source of useful Marvel adaptations. Obviously, since the genes copied by the mimivirus are probably random in nature, this mechanism lacks the human selection factor from example 1 and probably does not have the power to create world where we see many many useful mutants per capita. If you've read this far, wow, thanks! I hope this provides a framework that gives you a satisfying scientific answer to how we might explain Marvel Mutants. [Answer] I've often wondered if the X-gene doesn't just "read" the other genes and try to make sense of them and interpret them in its own way. Like an English speaker picking up a book written in a foreign language (say, German) and attempting to read the book in English, except that rat in German doesn't mean a rodent. (Rat in German means advice, counsel, or council.) For example, say you've got some junk DNA in there that the X-gene reads as "start power" and some more further down the line that the X-gene reads as "cognitive predictive ability 1000%" and a little further down the line the X-gene reads "end power." In a person without the X-gene, that's just junk DNA and it doesn't mean diddly. With an X-gene, that person can predict the future. There would also be people with X-genes who did not have any combinations where the X-gene made sense of it (inactive X-gene) as in the case of Mystique and Sabertooth's son has NO powers, although ostensibly he has to have an X-gene, who joined Friends Against Humanity. It would mean at least one of the "non-mutant" parents of mutants have the X-gene but no viable combinations of DNA. Genetic Recombination during Meiosis: "Genetic recombination is the production of offspring with combinations of traits that differ from those found in either parent. In eukaryotes, genetic recombination during meiosis can lead to a novel set of genetic information that can be passed on from the parents to the offspring." It would explain why mutants may always be a minority. It would explain why similar or the same powers are more inclined to run in families yet entirely unrelated powers can still belong to close kin. Ideally, as we saw more mutants getting married and having children (rather than saving the world) we would also see more non-mutant or non-powered offspring of mutants. (Won't that fuck Magneto up? Teehee.) Anyone have any thoughts on this? [Answer] Ironically, (for the question's exceptions), I recall a conversation where it was mentioned the most likely explanation was an in-universe source of what we call "handwavium" - that is, an actual something, some kind of substance, which happens to affects probability. It would cause both good and bad luck, taken to extremes, and increasing the odds for strange rather than logical consequence. The worlds of the comics would then be the natural results of systems and species evolving in an environment with such a resource, with occasional exposure as a natural hazard (since "both good and bad" is taken quite literally). More chances for "beneficial" changes, by those more directly exposed, less for successful reproduction because they're playing heroes and villains instead (occasional insanity, visible alteration which is not socially accepted, much more dangerous lives, yanno, all that). It probably means strictly selecting for genes which have almost beneficial mutations - since the actual "successes" might not reproduce, but their families have a much better chance. I imagine it would be a little like evolving to live in a high radiation environment, species might have a lot more unstable mutations visible, since anything that can shift around, does - but the resultant species would also be tougher, becoming more likely to survive mutation since any genes which could easily mutate to something irrecoverably bad were selected out of the population. Or something like that. Or alternatively, other answers mention there should be corresponding numbers of neutral or negative mutations. A very little handwaving might start this off a little higher mutation rate, a little higher fertility rate, and a little higher rate on the non-viability spellchecker that aborts the worst mutations, and the birth rate would look mostly the same. If the overall number of mutations was lower than the other answers suggest, but had been going on the whole time instead of just "when mutants appeared", evolution would eventually kinda select against those genes that would tend to mutate into non-survivable, and for sturdy redundant genetics, and the bias towards neutral and beneficial mutation would build in the population over time. The rise in "useful" mutations might have to do with that timeline, when the kinda-beneficial starts outstripping the neutrally mutating genes (The universe has such beings "occasionally" popping up in history, then becoming common in the era it is set, I think). There should be a pretty pronounced trend towards variation, visible variation, if so - but given trends we see in our own history, with religious witch hunts, and the rise of scientific skepticism, I could see a concerted and prolonged effort to, um, "select against" visible mutations (aka witch hunt, for minimum few hundred years), followed by a social shift, once it has worked for a while, where society kinda forgot it was really real and not just "superstition" and stories after another few hundred years of nothing too visible, and where occasional oddities hide - which means the appearance of beneficial mutations, is really reappearance of survivable variation once it is no longer being, um, quite so actively selected against. Increasing global migration lets populations of genes mix, and all the recessives pop up, or something - with time enough for useful to get really useful over generations, but a mostly forgotten artificial historical bias against "visible" to explain why most of the people of that universe didn't know/remember/believe all about it until relatively recent in the universe's history. Which would mean mutants aren't the "next evolved species" so much as a complex and forgotten piece of the whole human race, but then there's nothing quite so human as the tendency to stand on a soapbox and assume they're better, more advanced, and eventually going to triumph and replace those they deem "inferior". [Answer] The simplest scientific reason is that it's not our universe. There needs to exist something, a form of mysterious and by our standards an inexplicable form of energy, that powers psi abilities, skills, and powers. However, this works it must linked to the biology of persons, animals or plants that can express these psi-powers. If the basis of psi-powers is inherently biological, then this will influenced by the genetic nature of the persons. There might be genes that are directly responsible for specific psi-powers or it may require complex combinations of genes to enable psi-power(s) to be expressed. If it's the latter, then the fact that mutants seem to have suddenly arisen is due to a critical mass of persons developing in the general population, with sufficient combinations of genes to have psi-powers. An explanation of this sort is given in John Ridley's superhero novel Those Who Walk in Darkness (2003) to explain the recent appearance of numerous so-called supernormals. As explanations go, it's not too bad. As for the nature of the psi-energy responsible for mutant powers that's a whole different area of quasi-scientific fabulation. ]
[Question] [ What will happen if just today we find out that no more oil left in the planet. With the current infrastructures, how would that change, affect our lives? What is the fastest replacement? [Answer] Assuming it's only oil that has ended overnight, leaving coal and gas. The major impact will be on the transport industry. Bio diesel production is fairly energy intensive, so in the short run, it's unlikely to replace diesel. Not to mention, that it takes a few months for the crops to mature, crops which need farm equipment running on oil for industrial level production. Going by history, oil shortages in WWII Britain led to the use of water gas, generated from coal. This will probably be the immediate substitute in countries that have available coal and sufficient extracted reserve. Alternately, it's fairly trivial to convert oil vehicles to gas. In the longer run, electric vehicles may prove more economic than biodiesel, considering the logistics of farming and hydrogenation. The above assumes that electricity supplies are not affected as they are powered by gas, coal and nuclear+renewables. Assuming ALL fossil hydrocarbons (i.e., oil and gas) disappear, the major issue will be electricity and heating. Again, coal will be an immediate substitute, to supply coal gas and water gas to run gas based plants. Nuclear and coal plants will be run at maximum possible capacity to meet the shortage. Any renewables already completed will be installed as fast as possible to ensure the grids keep working. Nuclear plants take years to set up, so will probably see funding lost as the authorities try to solve the immediate crisis. In both cases, electric/diesel trains will be shunted out and any steam trains available will be pressed into service.Nuclear powered military vessels will be reassigned as tugboats, especially any due for decommissioning. Given the local public disturbance, it's quite unlikely any nation will be thinking of starting trouble, as most security forces will have their hands full, but there ARE nutcases aplenty. Most likely, there will be a rise in piracy on the high seas. Air travel will stop in the short term, as electric motors are developed to replace jet engines. Hydrogen fueled jets are a possibility, but there are major safety implications at the moment; I don't see hydrogen powered ramjets in the near future. Electronic devices will jump in price, as electricity gets rationed and prioritized. Facebook and their ilk will probably go out of business. Country that rely on importing their food will start to see shortages and probable riots as their reserves run out as major trade comes to a halt, while food exporters will see huge surpluses rotting, some of which can be diverted to producing biomass based fuel. On the other hand, many of these countries use mechanized agriculture that will no longer be viable. In fact, the Amish will probably be the best off in North America. Countries relying on trade to support their economy will find no buyers and no way to transport their goods. China's economy will effectively drop dead once it can no longer supply cheap manufactured goods to the west.Its economy runs on cheap oil, and produces mostly plastics, including artificial fibres and electronics. No raw materials and no market means there are suddenly millions of unemployed with no electricity, no transport and no prospects or distractions. If the government fails to feed them all, it can look forward to another Glorious Revolution; if it succeeds, it needs to find something for them to do to get the economy moving, while facing simmering discontent. Fortunately, for them, it's a command economy. Japan will starve within weeks. South Korea's economy relies on shipbuilding for the oil industry and electronics for the most part, and will stall (confirm?). Fortunately,they have a much lower population than China and might successfully feed themselves, but, like the Chinese, will face energy shortages and unemployment. North Korea, has nothing now and will continue to do so. The only people immediately affected would be the elite, assuming they have sufficient food. Russia + no fuel = Winter is coming. Massive death tolls through freezing, especially since they've been moving people to Siberia (free land and tax breaks, IIRC). Ukraine, self sufficient in food, and might actually stabilize since the big powers have other concerns. Europe in general, mostly CAN grow their own food, but prefer to import. Lots of people will get unemployed as the modern economy stops, but lots of new jobs in restarting agriculture, possibly returning to a pre-WWI economy. It's small enough that local shortages can be met easily and with comparative low oil dependence, after an initial bump, they'll stabilize. Africa failed to develop because too many interests were jockeying for influence for the past 200 years. With these interests otherwise occupied, it can start to grow. Expect civil wars and massacres as the people in power try to hold on without the support of their patrons. The middle east: no oil, the governments in power are of no interest to anyone, and the people have a LOT of festering resentment. Expect fireworks for the next 50 years. Afghanistan may stabilise. Pakistan, with the military's movement limited, will splinter, as will India. With the rest of the subcontinent, it depends on whether the governments can continue to provide the basics; otherwise, the entire subcontinent will break into small city states, ruled over by strongmen. Australia will suffer badly in the short term, New Zealand will fare better--less dependence on mining, self sufficient in food. Indochina is self sufficient(?) in terms of food, the manufacturing economy will collapse--no exports. South America: Brazil's rainforests will be saved. Economies dependent on oil and manufacturing will stop, civil unrest, etc. etc., see above. Outside the major cities however, there may be little change to people's lifestyles. You know, until I started writing this, I had no clue how many people would NOT be affected by the end of fossil fuel. Amazing, when you consider that it drives over 90% of the economy. Economic disparity means some people are living their lives like it's 1880. If anything, their lives will actually improve: less pollution from upstream; expensive travel making it less economically attractive to bother them. Political economics aside, crude oil derivatives are used everywhere, plastics, medicine, food additives, insulation (both electrical and thermal), pesticides, chemically inert packaging, perfumes and solvents, fertilizers and plenty of other things I can't think of off the top of my head. For most of these, there is no ready substitute. Shortages will lead to black markets and rent-seeking as people try to prioritise their needs, e.g., should you use your existing stock of LDPE for making food packaging or medicine packaging? Should you buy acetone from a nail polish factory at high rates for your pharmaceutical factory producing cancer medicine? Please note, I'm not a chemist or pharmacist, and not familiar with chemical manufacturing techniques. [Answer] ### Point on the situation First of all, one should realise, that there's quite some prospection done today. This allows to evaluate the amount of oil we have left. Furthermore, not all the reserves are being exploited. Some because they are more costly than others (so we leave it for until the price make it worthwhile), some due to political debates (China's See, Arctic, etc.), and some because of ethic/technology barriers (fracking). So if we were making some mistakes in our estimation, we'd still have alternative places to go to. Now there are some debates as of how long can we run with what we have right now. This is due to, to a large extend, uncertainty on the consumptions of various countries (China). ### Where do we use it? We'll simplify greatly, but the main uses of oil are * transport, * energy (producing electricity), * plastic, * roads ### Magic spell gone wrong Let's imagine that one wizzard was passing in the vicinity of the Earth, and one of its spell went astray and made the whole oil disappear. I'll let aside the whole sociological and political issues (wars, inflation, putting down the economy, etc.) to concentrate on the technical point. I don't claim they can be used one to one (amount, price, etc.) but they are likely to be used. * energy: more gas, more coal, more nuclear fission... and more of the others. In a way that's the easiest. It would be more expensive, but I think that would not be too complex to set up. * roads: I have no idea, to be honnest. But with the oil already extracted and the roads already built, we would probably have a few years to find some new alternative. * transport: electric cars running on batteries, cars running on hydrogen fuel cells (that's a rising technology, and believe me, I know what I'm talking about), but also bio-oil. Some diesel engines have been known to run on vegetal-oil (coming from farming). So road transports would not be a too difficult problem after a time to adjust. People would probably walk, take public transport, ride, etc. more to compensate. Planes and ships are more complex. Ships may start sailing again. Solar energy and electro-motors might make it faster. But I think people would have to find ways around using the large container-ships. You'd probably have less bananas to eat. Planes, maybe airships would come back into fashion. * plastic: there are some bio-plastics developped. I know that it's also an expanding technology. We would probably reduce the consumption drastically, and that would allow for those alternative plastics to take the spot. ### Conclusion It's very unlikely that all the oil disappear from one day to the other. And there are many alternatives being developped. So oil would be replaced by different technologies in different applications. But you can probably write a book on all the sociological and/or political implications. [Answer] Economically and socially it would be catastrophic. Most countries in Europe have only a few month of oil reserves (3 month normally), and they can buy it from one another (for some). The USA would last a few month with their reserves too (they might have more, but they consume a lot more) [Reserves available per country](https://en.wikipedia.org/wiki/Global_strategic_petroleum_reserves) [Consumption per country per habitant](http://www.indexmundi.com/map/?v=91000) I suppose these number are calculated with a "with normal daily consumption for everyone". Because of the scarcity of oil, buying or using it would probably be restricted in most country. (a few available to citizen, and the rest for miltary/police/hospitals/etc.) Of course, oil prices would rise terribly, and people would take everything they can the day they learn that it has disappeared, either to keep it or to resell it later at higher price. Governments will have to react quick, promote car pooling and public transportation, etc (tax reduction, or even by law). Some countries already have pretty good public transportation systems, but that mostly concern big cities anyway. Activity in more rural areas will be seriously injured. If they don't, a country that can't go to work and consume would probably die. If they do and it works, they might survive long enough for alternative energy to come to the rescue (bio energies or electricity) or for the system to adapt. I am quite surprises about how much oil taxes are important for most country. [(oil revenue % per gdp)](http://www.theglobaleconomy.com/rankings/Oil_revenue/) So it wouldn't be that bad in that sense As a side note, there was a strike at an oil company, recently in France, forcing most gas station to shut down or to restrict how much you can buy. Some people went to take only a few liters of fuel, and the queue would be incredibly big and a lot more stressful. I guess psychologically, that wouldn't be a good thing too, but I'm not really sure how any society would react well ... <http://www.thelocal.fr/20160525/latest-where-in-france-the-petrol-shortage-is-biting> Of course, most of this answer is based on oil usage for transportation. Oil isn't used a lot for electricity. [(oil usage for electricity)](https://en.wikipedia.org/wiki/World_energy_consumption#Energy_supply.2C_consumption_and_electricity) And plastic won't be really important when this happens (maybe for electric cars) compared to the rest. And of course the more a country needs transportation, the more its direct effects would be important. I say "direct" because if a country falls because of this oil shortage, it will impact every country that does business with it. With dominos effect this might destroy the whole economy. Because of that, a lot of country will have to help each other to prevent anyone strong to fall. [Answer] Electricity and synthetic hydrocarbons would be our only choices most of the small-sized transport vehicles would shift to electric power instead of gas. This includes cars and motorcycles. Larger vehicles would run on either dextrose (sugar), alcohol or synthetically prepared hydrocarbons (aka petrol and diesel). This includes things such as buses, airplanes and medium sized boats. Gas stoves etc would have to be abandoned initially in favor of firewood until a method is discovered to conveniently break down large hydrocarbons into small ones. [Answer] ## Biodiesel > > Biodiesel is an alternative fuel similar to conventional or 'fossil' diesel. Biodiesel can be produced from straight vegetable oil, animal oil/fats, tallow and waste cooking oil. The process used to convert these oils to Biodiesel is called transesterification. > > > [source](http://www.esru.strath.ac.uk/EandE/Web_sites/02-03/biofuels/what_biodiesel.htm) ## Bioethanol > > The main sources of sugar required to produce ethanol come from fuel or energy crops. These crops are grown specifically for energy use and include corn, maize and wheat crops, waste straw, willow and popular trees, sawdust, reed canary grass, cord grasses, jerusalem artichoke, myscanthus and sorghum plants. There is also ongoing research and development into the use of municipal solid wastes to produce ethanol fuel. > > > Ethanol or ethyl alcohol (C2H5OH) is a clear colourless liquid, it is biodegradable, low in toxicity and causes little environmental pollution if spilt. Ethanol burns to produce carbon dioxide and water. Ethanol is a high octane fuel and has replaced lead as an octane enhancer in petrol. By blending ethanol with gasoline we can also oxygenate the fuel mixture so it burns more completely and reduces polluting emissions. Ethanol fuel blends are widely sold in the United States. The most common blend is 10% ethanol and 90% petrol (E10). Vehicle engines require no modifications to run on E10 and vehicle warranties are unaffected also. Only flexible fuel vehicles can run on up to 85% ethanol and 15% petrol blends (E85). > > > [source](http://www.esru.strath.ac.uk/EandE/Web_sites/02-03/biofuels/what_bioethanol.htm) These are already in use in many areas, but it's not good for biodiversity to start creating them on massively industrial scales. It tends to lead to forest clearance, monocultures etc. but given a sudden removal of oil supplies they're the quickest and easiest source of light fuels as the infrastructure is mostly already in place and no new technologies or distribution systems are needed. [Answer] Flywheels, flywheels and..flywheels with really good batteries. I think localized electrical power will take off with a focus on ablilty to get power from multiple sources: Wind, Solar, Human/Animal kinetic energy, grid.. but this speaks mostly of fuel for generators and vehicles. Plastics on the other hand will rely more heavily on material science. Some may be bioplastics but if we find ourselves in an oil-scarce world it may well be a biology scarce world as well. We may start beefing up our production of CO2 type plastics. We may speed up the nanomaterials race to reduce friction in enines, gears, etc where lubricant would generally exist. Without certain oil-based products, we'll also need specialized surfaces. ]
[Question] [ So this question is about a humanoid species I was thinking of: They are semi-immortal and live long life spans, which poses the problem of not having enough space for new memories after a long time. If they developed a second brain, where would the second one be placed in their body? [Answer] Considering your humanoids are semi-immortal and extremely long lived memory may not be a problem. Even humans, who are actually longer lived than other equivalent species, can get by quite successfully with memories that don't store everything we have learned or experienced, so it can be expected your humanoids can do the same. Humans can do this storing information and memory outside our bodies. using writing, recorded images, and relying on the memories of other people (social memory is surprisingly powerful). Also, they have have developed social and technical systems to further enhance capturing information about their lives. This could be wearable technology or all -pervasive surveillance technology or even assistants who accompany the semi-immortal humanoids and record what they are doing to make it available for retrieval in future or when required. This answer has to be negative the humanoids don't need two brains. Extrasomatic information storage or external memory can more than do the job. Besides the human brain consumes a quarter of a person's metabolic energy. Having two brains will consume, how obvious, twice as amount. This means the humanoids will either spend more time eating or it will keep their bodies trim and slim. [Answer] A few possible answers come to mind: ## Expanding Skulls If you really examine the human brain in detail it is actually split into two hemispheres and could be considered in some respects as already being two brains. This is a good thing as the extra capacity makes it possible for redundancy and recovery from brain injuries. The human head is already too big for live birth, and human babies are born without a solid skull as a result, with the bones only fusing after birth. An immortal (or very long lived) alien species could have something like this occur periodically, with the divisions in the skull softening and expanding to account for additional brain volume. ## Secondary Storage In dinosaurs and other extremely large animals, a nerve cluster or second brain is often found further down the body allowing for faster response times given the long distances involved from the extremities to the primary brain. To a certain extent the human spinal cord acts in a similar manner, with certain reflex responses being processed independent of the brain, thus responding faster. An alien species could have these nerve clusters expand during their lifetime to not only allow reflex response, but also as expanded memory storage. This could lead to some odd mental behavior, memory stored in these secondary brains would take longer to access leading to odd delays when remembering things from these secondary brains. The expansion of these brains could also have negative effects, for example if a humans spinal cord started expanding, it would have negative effects on the spines ability to bend or otherwise affect mobility. ## Offsite Backup It is difficult to remember everything, which is why memory is often so subjective and usually non comprehensive, the way even short lived humans deal with this is to offload memory requirements to technology. Writing at its most basic level does this, but given sufficient technology many science fiction authors have explored the possibilities of transferring and storing memories or an entire consciousness using computer technologies. Advanced long lived alien species could utilize advanced technologies to store memories into a backup medium, with the ability to load it back into their biological storage as needed. With writing this knowledge recall and transfer takes a long time, but more advanced direct methods could be much faster. [Answer] You can make spinal cords evolve to fulfill the role of a second brain . They do not occupy additional space in the human body. [Answer] The human brain has a frankly ridiculous capacity for information, so I find it unlikely that they'd run out of space in it in less than 1000 years. However if such a species did exist and they lived for, say, a millennium, their brains would probably be far more compact than ours are, and so have more room for data storage. [Answer] [Easy](https://en.wikipedia.org/wiki/The_Man_with_Two_Brains): just involve a mad scientist. ![two brains](https://i.stack.imgur.com/3Uz9n.jpg)] On a more “hard s-f” note, look at the [Rukh](https://en.wikipedia.org/wiki/Saturn_Rukh) designed by writer and scientist Robert L. Forward. ![Rukh cover](https://i.stack.imgur.com/Y9vBZ.jpg) The animal was huge and you can see the human spaceship in comparison. It had a manipulator tenticle with eyes and brain for each side. Forward's character points out that the eyes need a brain right behind them, not tens of miles away. So the creature evolved 2 brains, one for each side. This was further developed by the ever-flying nature of the Saturn dweller, as they took turns sleeping. There's two reasons (one for each brain!) [Answer] Giancarlo Ventura Granados has already mentioned what I had in mind (+1 to him for that). Instead of giving them a second brain, you could fulfill the same objective by giving them thicker spinal cords with the ability to store data/memories. The spinal cord might also have a couple of bulges at two points which would serve as enhanced storage areas and might also assist in complex thought processes by doing background thinking on detailed aspects of the subject. [Answer] An interesting problem, especially as we have a poor understanding of how the brain functions in the first place. A few handwave ideas come to mind: 1. As an immortal human, the brain will need to be rewired anyway, so one modification would be to follow the lead of Dolphins and have the brain "sleep" one hemisphere at a time. Since sleep seems to have some importance in the processing and storage of memories and experiences, this would allow the brain to have a faster "duty cycle". As well, the waking brain hemisphere could have a role in consciously selecting and editing memories in the sleeping hemisphere, so you don't end up storing vast amounts of trivia. 2. In addition to the left/right hemispherical split, the brain is also a complex three dimensional structure. If you imagine an onion, the brain can be "peeled back" into three layers, colloquially known as the forebrain, midbrain and hindbrain. The forebrain is primarily where cognitive thinking takes place, the midbrain is where complex "instinctual" behaviours reside and the hindbrain is where the automatic functions (breathing, heart rate etc.) are controlled. While we don't clearly understand the hows and whys of how the various parts work or are interlinked (internet answer-we do know a lot, but not in an easily summarized fashion), deeper knowledge might allow a sufficiently advanced race to edit or modify how each layer is "wired" and edit the way information is stored in order to increase the storage density, "read/write" times or even retrieval (much like adding RAM to a computer makes it operate faster). The overall effect then is to treat the brain as a complex, three dimensional object, with essentially six major units (three layers, divided into two hemispheres) and then optimize the layers and hemispheres to create the effects required. In essence, instead of having two physically separate brains, you have a higher level "multi core" processor in your head. What may be ironic about this answer is as we understand more of how the brain works, we may end up discovering this is how it works anyway.... [Answer] Apparently, humanoids already have a second brain, the gut. Your make-believe humanoids could just have a more developed second [gut-brain system](https://www.scientificamerican.com/article/gut-second-brain/) than we currently have. > > ...even the steeliest are likely to experience that familiar feeling of "butterflies" in the stomach. Underlying this sensation is an often-overlooked network of neurons lining our guts that is so extensive some scientists have nicknamed it our "second brain". > > > A deeper understanding of this mass of neural tissue, filled with important neurotransmitters, is revealing that it does much more than merely handle digestion or inflict the occasional nervous pang. The little brain in our innards, in connection with the big one in our skulls, partly determines our mental state and plays key roles in certain diseases throughout the body. > > > Although its influence is far-reaching, the second brain is not the seat of any conscious thoughts or decision-making. > "The second brain doesn't help with the great thought processes…religion, philosophy and poetry is left to the brain in the head," ... > > > The gut-brain system is incredibly complex and not yet fully understood. We could already be ruled by it more than we currently accept but you could develop the system to be more detailed for the purposes of your story. > > Technically known as the enteric nervous system, the second brain consists of sheaths of neurons embedded in the walls of the long tube of our gut, or alimentary canal, which measures about nine meters end to end from the esophagus to the anus. The second brain contains some 100 million neurons, more than in either the spinal cord or the peripheral nervous system, Gershon says. > > > This multitude of neurons in the enteric nervous system enables us to "feel" the inner world of our gut and its contents. Much of this neural firepower comes to bear in the elaborate daily grind of digestion. Breaking down food, absorbing nutrients, and expelling of waste requires chemical processing, mechanical mixing and rhythmic muscle contractions that move everything on down the line. > > > Seperation of the two brains, in a similar way to seperating the two hemispheres of our head-brain, could play a more important role in your world. In your world, para-, tetra-, and quadaplegics could all have different degrees of two-brain damage. ]
[Question] [ If you have a series of dams built along a valley, what will happen if the last one in the line fails suddenly and catastrophically? Scenario. You have a dam wall about halfway down a long narrow valley. It is made up like a sandwich. A layer of large shaped granite rocks connected by iron and metal bands, a internal layer- a mix of compacted rubble, and roman like concrete, and then a second layer of large rocks. The dam wall shape is designed like hoover dam with the curve against the water pressure. After a few decades to centuries the wall starts to deteriorate. You are capable of 'dredging' up the collected silts to use on your farmlands but you don't have the technology level of the original dam builders so you can't 'properly' maintain it. So to protect your existing thriving farmlands and cities downvalley you build a second dam wall a couple hundred metres from the original wall before it deteriorates too badly. The original does not collapse or fail. This new dam area is allowed to fill up and the water pressure on both sides of the original wall 'maybe' helps keeps it upright. To allow fish and water transfer between the two there could be alterations done to the top layer of the original wall like permanently open riverlocks (there could be a system to close these locks if necessary) or maybe just allow the wall to be completely submerged. I have for a long time thought that they would have a way of moving water from one area to another. Diverting and managing water flow in and out of the dam/s to surrounding valleys. Using waterwheels, arcimedes screws, maybe even some sort of primitive suction action. Another couple of decades/centuries go by. Question What happens to the original dam wall if the second dam wall fails suddenly? Would the sudden loss of water pressure supporting the one side cause the original wall to fail at the same time? Especially if the original wall may be compromised internally by water seeping into the middle sandwich layer. How do I get the original wall to hold? Note I'm asking on worldbuilding as I'm not aware of any real life examples of dam's in series and dam failures like this. EDIT I do believe I am actually thinking along the lines of the combination arch-gravity dam rather than just the arch dam like Hoover dam. [This Question](https://worldbuilding.stackexchange.com/questions/28794/a-dam-that-looks-like-a-brick-wall-because-it-really-is?rq=1) asked about a dam made up of blocks of stone rather than a continuous concrete setting seems to imply that a dam similar (but not exactly) will last at least for a century or two before failing due to the stresses. [Answer] # No, it cannot hold Reality check: your premise is wrong in that you have built an [arch dam](https://en.wikipedia.org/wiki/Arch_dam) by materials that are not stable enough to support the arch. This means that that you have a dam that does not follow any kind of convention or known engineering principles. But let us ignore that and instead just assume that what you actually mean is that you have a curved [rock-fill embankment dam](https://en.wikipedia.org/wiki/Embankment_dam), like this one: [![enter image description here](https://i.stack.imgur.com/fnKlq.jpg)](https://i.stack.imgur.com/fnKlq.jpg) Will that hold if you 1) submerge it and 2) the downstream dam suddenly gives way and all the water between the dams drain? Answer: there is no chance it will hold. First you have submerged the dam, meaning that all the material on the downstream side is unsecured. The entire dam [liquefied](https://en.wikipedia.org/wiki/Soil_liquefaction) even before the disaster starts. Second, you get a massive movement of water, which will wash much material away on the downstream face of the dam. Third, the water on the upstream side of the old dam will flow over the edge and start washing it away there too. Fourth, as a premise you said the old dam was already weak and beginning to deteriorate. These things together means that the old dam simply cannot hold if the new dam fails. It is not a matter of forces suddenly changing, but that of water movement that simply washes the dam away. Here is what it looks like when an embankment dam fails: [Teton Dam disaster](https://www.youtube.com/watch?v=cdOGPBnfoKE) And do note that this dam was not submerged on the downstream side. [Answer] As is so often the case on this site, I believe that the answer is: It depends.¬† It depends on how much the original dam has deteriorated since the building of the second one.¬† I believe that the result will be the same as if you opened a valve (lock) in the lower dam and allowed all the water in the buffer zone to drain slowly.¬† This is approximately the same as what would have happened to the original dam in the same amount of time, if the second dam had not been built, except that ignores the beneficial effect of the presence of the new dam on the old one.¬† (BTW, I don‚Äôt know whether the new dam would protect the old one in the way you describe, but you didn‚Äôt ask that.) I suggest the following thought experiment: Consider a shelf (e.g., a bookshelf, or a horizontal surface in a cabinet/closet) that is loaded with a weight that does not exceed the capacity that the shelf was designed for.¬† The shelf is beginning to show signs of stress, so you put your hand on the underside of the shelf and push up, to counter the weight that is pushing down.¬† You stand like that for years.¬† Then the doorbell rings, and you run to the door, abruptly removing the support from the shelf.¬† Would you expect this to cause the shelf to collapse?¬† I wouldn‚Äôt.¬† I would expect the same dynamic as I described for the dam: if it has further deteriorated enough in the intervening years, then it will collapse (as it would have done by now if you hadn‚Äôt been supporting it).¬† If it‚Äôs still capable of bearing the load, then it resumes bearing the load. [A comment](/q/46828/dam-wall-failure-domino-effect#comment131506_46828) mentions ‚Äútwo forces at once ‚Äì the force of the water behind [the old dam] combined with a vacuum effect from the water moving away from the front.‚Äù¬† I believe that this is a misconception.¬† There is no such thing as a ‚Äúvacuum effect,‚Äù per¬†se.¬† What we perceive as a ‚Äúvacuum effect‚Äù is just the lack of balance between two pressure zones.¬† If an unpressurized spacecraft (in the vacuum of space) is compromised by a meteoroid puncture (or by somebody opening a window), the papers on the desk, etc., won‚Äôt suddenly fly around and toward the breach.¬† Yes, obviously, the old dam will suddenly be subject to the unabated pressure of the water behind it, but there won‚Äôt be any ‚Äúvacuum effect‚Äù in addition to that.¬† The turbulence of the water rushing out of the reservoir might introduce a chaotic effect, but (IMHO) that would be brief. ]
[Question] [ Let's say that humanity has started a galactic empire, one of the things the embassy of Earth must do is communicate with a variety of alien species. * The Vogavlüeans - The language of these subtropical hexapodal creatures consists of a variety of chirps and squeels. * The Myrshakälans - The language of these bipedal, four armed aliens consists of hisses and voiceless breaths. * The Bochahë - This species of deep sea merpeoples language consists of sonars and squeeks. * The Triacyclicia - These 3-gendered anteater like creatures communicate with eachother using not sound but touch. * The K'tathi - This collective consisness species' language consists of [pheromones](https://worldbuilding.stackexchange.com/questions/45769/pheromone-based-language). * The Seräphii - The Seräphii communicate using a strange language of click consonants. * The Daleth - This flying nocturnal species relies on a system of chittering and echolocation in order to communicate Obviously, the rules of probably say that it's extremely unlikely that these aliens would even be able to pronounce human sounds. How can the humans reliably communicate with the above aliens? How can the aliens reliably communicate with each other? [Answer] This problem can be overcome using abstract digital characters, essentially an alphabet much like ours, itemzed and encoded into codepoints similar to our own [unicode](https://en.wikipedia.org/wiki/Unicode). Since encoded characters abstract away the physical, sonic qualities of speech into semantic characters (‘letters’ in our language), they can be used as a universal format of communication. They are easy to learn; in fact you are reading this answer right now using abstract digital characters, all without hearing any auditory speech at all. And they are easy to transmit—we already know how to encode them into binary bits, essentially a glorified morse code, and we are quite good at this, see [UTF-8](https://en.wikipedia.org/wiki/UTF-8) and associated technologies, which are extensible and allow for variable bit widths. Since the characters themselves are abstracted away from the physical qualities of speech, each species can develop its own way of rendering and understanding them. For humans, we use technology known as [fonts](https://en.wikipedia.org/wiki/Font) to convert the characters visually into representations called [glyphs](https://en.wikipedia.org/wiki/Glyph) which can be read on paper or on screens. For humans without sight, we instead represent these characters as raised dots known as [braille](https://en.wikipedia.org/wiki/Braille). Notice that the characters and their meaning are unchanged; only the representation is different. Other species could render abstract digital characters as any combination of scents, sounds, shapes, electrical mind signals, you name it. [Answer] If neither of the parties can emulate the other party's way of speech, by necessity, a translator is needed. Unless bio-engineering advances enough, such a translator would need to me mechanical/electrical. A better solution, which requires more cooperation by the other species, would be to create a language that can be spoken by everyone. Since everyone can move and see (at least if your species make evolutionary sense), such a language would best be of a writable form. A broad language with symbols derived from pictures would probably be best to make sure it can be easily understood and learned by other species. Another, more complex, language would be prepared for use when the "easy" language isn't enough, but would require at least some individuals of the other species to make considerable effort to learn it. [Answer] They can communicate using mathematics - By using prime numbers and patterns, you can show at least some knowledge of advanced mathematics. The book [Prime Numbers and the search for Extraterrestrial Intelligence](https://math.dartmouth.edu/~carlp/PDF/extraterrestrial.pdf) goes into this in more detail. In fact, the movie Contact also uses math to communicate. Aliens, through the use of numbers, send blueprints to the humans, which helps them to build a communication device. Having the technology to communicate with other races pretty much guarantees that the civilization(s) in question have access to advanced mathematics. ]
[Question] [ I, an undergraduate god majoring in worldbuilding and accelerated evolution, have been tasked with a simple yet sophisticated job, in lieu of a senior thesis paper. My task: design a world populated with macro-life, which must get them to the point of space-travel as quickly as possible. I have 4 billion years on my hands, but I need to use as little time as I can to accelerate these organisms to this point. Limitations: * No technology given directly. * The starting organism is basically a lizard, and no more advanced. * No other creatures exist here that aren't earth-like. * The planet itself cannot be smaller than 1.3 times our own moon. * Flora is allowed, but only earth-like flora. * No other organisms exist in this solar system, or can enter. * No technology is allowed to descend to the planet, not even cameras. * We are following earth-established physics in this system. * Spaceflight is defined by leaving the planet and traveling at least 7,000 miles away from it. * The planet has an earth-like atmosphere, with identical pressure. * I can not influence anything, nor can I control anything, on or off the planet once the simulation is launched. In other words, I must accelerate them to this point without any sort of direct help. [Answer] "Spaceflight is defined by leaving the planet and traveling at least 7,000 miles away from it." Good news, you can win on the first day of the simulation given this very broad definition of spaceflight. You simply start your simulation with a good sized asteroid already on its way about to impact the planet with your lizards. We already have proof that there have been impacts on Mars that have launched [rocks from Mars into space that have subsequently landed here on Earth](https://en.wikipedia.org/wiki/Martian_meteorite). You just need to have an asteroid lined up with your planet such that it hits the planet where there are a bunch of the lizards very near by to the impact point, but not directly in line. If it's large enough, and there are enough lizards around, you can be reasonably sure to kick at least a few of them into space. After all, the definition didn't make any mention of the space flight being of the lizard's design or the lizards having to survive the trip, or for it being repeatable. And an asteroid falling is not technology descending on the planet. [![enter image description here](https://i.stack.imgur.com/mjVym.jpg)](https://i.stack.imgur.com/mjVym.jpg) And hey, even if somehow you screw up your calculations and don't eject one in to space on the first day, you probably won't kill all of them. After all, some lizards survived such an event here on Earth awhile ago and in just 67 million years they made it into space: [![enter image description here](https://i.stack.imgur.com/GY40X.jpg)](https://i.stack.imgur.com/GY40X.jpg) [Answer] You need to establish an environment that encourages selection for intelligence. The earliest selection point for this would be tool use. The source lizard needs opposable thumbs and should be an omnivore with social tendencies. The Lizard needs competitors for resources that are as good or better with natural appendages. Ideally most of the competitors shall be carnivores. Then the lizard needs safe bastions where they can continue to propagate without being eliminated by the predators (Caves, trees, or places where calories are scarce). In such conditions the Lizards succeed when they work together as a group, or develop tools to aid them. These are the groups that receive more calories and can have more offspring. Long natural life spans could aid in knowledge transfer between generations. (At later stages this could prove a slowing process so test cases are needed) Frequent mating cycles combined with egg laying would prove useful. Development within the egg could allow for larger brain cavities. Right now humans have about as large of a brain cavity as will fit through the cervix at birth. Any larger and most pregnancies would kill the mother. Also, the nutrient density required for such an egg would be incredibly high. This could provide an emergency food source/early food storage technique. Planet placement. Placing the planet in a position where it is easy to observe other celestial bodies would encourage a culture that wonders about them and seeks to explore them. 2 suggestions. Have this planet in a binary orbit with another life supporting planet with a shared center of gravity. Then early astronomers like earths Copernicus and Galileo could use their telescopes and see evidence of life and potential intelligence on the other planet as early as the 1400’s (earth time line). It might provide an even greater impetus if this was one of two life supporting moons around a larger gas giant like Saturn or Jupiter (closer in for warmth). A relatively clear atmosphere. They need to be able to look up at the sky to see these things and wonder. Edit You also need a mechanism for the Lizards to communicate. Verbal or scent are probably the best. Scent can travel longer distance and can linger but is restricted by wind. So the Lizards need the capacity to make varied noises and to hear them, or to make varied scents and smell them. [Answer] Our lizardy space travellers need one thing - luck. Luck and motivation... two things: luck and motivation. And selective advantages... three things: luck, motivation and selective advantages. And late environmental pressure. four... no... Amongst the required... Amongst their needs... are such elements as... wait, I'll come in again. Our lizardy space travellers need luck, selective advantages and motivation. But mostly luck. Since you can set up your planet, but not your solar system, I'd look for one with a big umbrella. A Jupiter-like planet would be awesome to absorb the majority of those pesky extinction-level asteroids. (Some luck required here to have the rest avoid your planet. This is completely out of your godly hands, I suppose.) Also, pick a system with a healthy amount of radiation. Too little, and our starter geckos won't get too many mutations. Too much, and they may accumulate in non-viable sets. And die off with 64 pairs of arms and translucent, or something. Now's the moment: Set them loose! And let your 4bn countdown clock start. Motivation can come with survival at early stages, and conflict / environment threat later. Several shots at luck are required here. borrowing from our own past, they may require: * Early competition for resources with other indigenous life, not so aggressive as to drive them to extinction, and not so easy as to have them sit on apex without the pressure to change; * Permanent environmental pressure - frequent ice ages, for example, may be specially important to our little [poikilothermal](https://en.wikipedia.org/wiki/Poikilotherm) friends - that forces the population to migrate; * to be able to shed some of their atavistic feathers (aggressive behavior, mostly) once they reach a base technological level. A lifespan big enough for a long learning period and knowledge spread is also essential. Late competition can even come in the form of [same-system, non-indigenous lifeforms, if you're able to populate other planets as well](https://worldbuilding.stackexchange.com/questions/33627/how-would-the-inhabitants-of-one-planet-kill-the-inhabitants-of-the-other/33666#33666). A very risky move, since you can't guarantee that both will reach the same development level at the same time - but it may award extra God credits for originality. [Answer] Make spaceflight easier. Specifically you can't change the mass of the planet significantly, but can you speed it's rotation. Most space launches on Earth are to the East to take advantage of the Earth's rotation. If your planet rotated faster it would be easier to get into orbit. ]
[Question] [ Let's say we have cyborgs. They have human minds(mapped into software), but no human body parts and create no hormones. How would this affect their behavior, life and quality of life? [Answer] Dead. Or at least very broken The human brain requires hormones to operate. For [example](http://www.ncbi.nlm.nih.gov/pubmed/1330863): > > Hormones secreted by the adrenals, gonads and thyroid play an important role in mediating how the environment shapes the structure and function of the brain during early development, adult life and senescence. > > > If you were to engage heavily in genetic engineering, you may be able to create a H. sapiens derivative which needs no hormones, but thats a very different question. [Answer] From a small bit of [research](https://www.google.ca/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=what%20are%20hormones), I found that hormones act on different bodily functions and process such as: * Development and growth * Metabolism of food items * Sexual function and reproductive growth and health * Cognitive function and mood * Maintenance of body temperature and thirst While several of these don't apply to your cyborg situation, I would imagine that the cognitive function and mood still would. This is of course assuming that when you say they have a human mind you mean a physical, functioning human brain. Some more [digging](http://www.patienteducationcenter.org/articles/the-effect-hormones-memory-cognitive-function/) has revealed that women who have hormone therapy midlife have lower risk of dementia, and men with high levels of testosterone have better visual and verbal memories. These are based on studies which of course do not display causation, but merely a relationship between hormones and other cognitive functions. So for your cyborgs, it may actually be more likely to get something like dementia or they may have a faster decline in mental abilities overall. To speak to Cort Ammon's answer, it is mentioned that the brain is shaped and structured by hormones while in the different phases of life. However, this may not affect your cyborgs as I'm assuming they have a fully developed brain transplanted in them that no longer needs hormonal influence, if that makes sense scientifically. [Answer] Since the brain isn't available in an easily readable computer format, I think your 'upload' will already take care of most of the solution. ## Basic brain anatomy, biology, and evolution When talking about 'uploading a mind to a computer', people tend to think of uploading the conscious mind only. However, due to how the brain is constructed, it's pretty much impossible to isolate the conscious part only (mainly because there is no such part visible in the biology...). All the examples and basic understanding are taken from John Eccles' book on the Evolution of the Brain, by the way. Anatomically, a brain is a huge neural net (or, more correctly: neural nets have been created to imitate a brain's function...) where you can't just cut out a part you need and then expect it to function perfectly. Neural nets are more or less blackboxes that you feed with input, have a look at the output, and the output generates feedback that goes back into the box to edit the way the neurons make their decisions. That way, the next time you input the exact same stuff, you might get the same result again, but you also might get a wildly different one (or anything in between). This malleability is used to make the neural net learn. And pretty much every neural node inside this network is necessary, because it is part of the constant processing-feedback-improving machinery. Evolution-wise, there was a small lizard-like brain, first. It took care of the things a basic animal needs to live (and I am talking about pre-vertebrate basic here), including all sensory processing etc. Then there came a secondary shell with some higher functions afterwards, vertebrate level. It didn't replace the lower shell, or extend it, but just slapped on its higher functions like improved visual tracking/recognition without ever replacing the lower ones. Kind of like an icecream cone -- the top one is the most accessible for eating, but the lower one is still there and lickable. And then evolution decided on a third shell (mammals), the major part of our brains, and once again it was just slapped on top of the already-existing mess. Visiual processing, for example, takes place on many levels, so even people who are completely blind due to problems with the visual cortex can react unconsciously to visual stimulus because some very basic things are being processed in lower brain levels. Biologically, the brain uses highly inefficient ways of triggering the neurons -- it doesn't use copper wires to transmit electrical impulses (300,000 km/s) but a chemical transport channel facsimile that can transport signals at 50-1000 meters per second. Additionally, even if the signal gets transported to its target neuron, the neuron itself only gets activated in about 30% of the cases. Not to mention that due to it being a chemical process, there's a limit on how often the neuron can be activated in a certain period of time before it becomes unresponsive. ## The Cyborg Brain Basically, if you want to transfer a mind to a cyborg (and then still be able to recognize the mind as the person they were before), you need to model the entire brain including all the evolutionary waste, the ineffecient way of activating neurons, and the terrible redundancies. So, during the upload you get the unconscious part, too. And that includes the cerebellum (the earliest lizard-part of the brain that was there first during evolution) -- the part that contains control for most of the hormonal glands (directly or indirectly). You get quite pretty locations where the brain presses the button 'please release hormone XYZ', and an intelligent cyborg design will then provide a virtual hormonal gland that simulates the effect. But why keep a virtual hormonal gland at all? well, for one, hormones like adrenaline help the person react in dangerous situations. If the brain was jacked up like this all the time, it would lead to stupid decisions, but in emergency situations? Do it! Your cyborg probably already has such an... overclocking function, so why not link it to the adrenal gland trigger, too? Serotonin, oxytocine and dopamine create feelings of reward/nice/fun/feel-good. They are part of the body's huge punishment-reward system that makes sure the animal takes care of its survival. Or they make sure that you seek out social contact (oxytocine), which once again gives you a better chance of survival. If you deactivate all those mechanisms for your cyborg, you will get lone wolf psychopathic ascets that might also be suicidal rambos. You probably won't get a functioning human out of it. It isn't too much of an effort to create the virtual hormones. After all, you probably already have wired such a mechanism into your cyborg's body so that having an empty fuel cell will signal some pretty bad alerts, and that a full fuel cell gives good feelings. That sand in the gears hurts, and that when everything works perfectly smooth it's a great feeling. That when endangered, you can overclock your servos / gyros / artificial muscles to get out of the situation, but which wears out your parts very quickly when turned on 24/7. Concerning the sexual hormones -- not quite sure about them. On the one hand, the urge to reproduce is hardwired so deeply into the human brain that it becomes a MUST to give your cyborgs a way of having sex (two or more entities meeting in emotionally very intimate settings that result in highly pleasurable actions that get rewarded by a slew of feel-good hormones and emotional bonding). Are there sexual hormones necessary for that? No idea. After all, cyborgs don't need the hormones necessary for keeping their primary and secondary gender characteristics, and they don't need the testosterone for muscle building. However, in some job areas they might want to have the testosterone's effect of increased aggression and dominant behavior. Or the estrogene for whatever wikipedia says it is good for in Cognition and Mental Health. ## Conclusion If you want a human uploaded into a cyborg, you will need to take all the hormones (their simulated effects) with you -- if you haven't already done that just to make sure the human keeps their body alive/maintained and the consciousness accepts it as an actual physical body. [Answer] As a very simplistic answer. Wouldn't brains without hormones be computers. Or put another way. Are not all our emotions controlled by hormones. I look at hormones like a palette of paint with an infinite array of different feelings or colours. A cyborg without hormones would not have desire, hurt, pain, love, happiness or anger. Don't have a clue if this is correct or helps but it is an opinion. ]
[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. Okay, so the heat death of the universe is approaching. You can't stop it. You can't dodge it. What do you do? [You wait it out.](https://en.wikipedia.org/wiki/Heat_death_of_the_universe#Time_frame_for_heat_death) According to wikipedia, about $10^{{10}^{56}}$ years after the heat death of the universe, random quantum fluctuations will start another. Therefore, it would seem that it would be possible for a civilization to hibernate. Simply stop using energy until the new universe pops up. Maybe put yourselves in a bubble? Could it work? Note: I guess the question is, is this fundamentally impossible. I have a feeling it might be, but I'm not sure. [Answer] Based on the request for a hard-science answer instead of the one I put above. I'm keeping the other one because it is a lot more accessible. Exploring surviving the heat death of the universe calls for exploring the fringes of math, society, science, and survival. In comments, you mention "I guess the question I'm getting at is if there is some impossibility theorem that says "all bubbles during the heat death pop" or something. " The answer is no, there is no impossibility theorem like that, but you asked for the wrong theorem. The first issue is defining what a bubble is. If your bubble is viewed as "part of the universe," then heat death has not yet occurred because your bubble contains information. So you clearly intent to treat the bubble as "outside of the universe," which by the same definitions as heat death means you cannot make classical measurements about the state outside the bubble. See [Maxwell's daemon](https://en.wikipedia.org/wiki/Maxwell's_demon) for an argument why. Now the problem becomes that the universe is not reborn in $10^{10^{56}}$ years. Quantum mechanics doesn't do things on a schedule. What that theory actually states is that it is possible that, through quantum mechanics, a waveform similar to that of a universe (such as a dirac delta function that could serve as a big bang) will occur due to random effects. Two key takeaways here. First it assumes that QM is 100% correct that there is absolutely no correlation between particles which cannot be modeled as random variables, and that those variables all are subject to the [Central Limit Theorem](https://en.wikipedia.org/wiki/Central_limit_theorem). In this case, the rebirth of a new universe will occur at a time also specified by a random variable with an expectation of it occurring at $10^{10^{56}}$ years. If you popped your bubble too early by 0.000000000000000000000000000000000000000000001%, you would find that you would be so far off that even a "bubbled" black hole with all the known mass in the universe would evaporate before genesis reoccurs. If you pop it 0.000000000000000000000000000000000000000000001% too late, you will miss genesis of the new universe, miss it evolve, and wake up during its heat death after all of its black holes have vanished. In fact, you wouldn't even be able to tell the difference between the two cases, because there would be so little information in the universe to study! (and actually, the bounds are much tighter than that. The actual bounds have roughly $10^54$ zeroes in them! I just didn't feel like holding the zero key down so long that we would start to enter heat death of the universe before we finish this answer!) This means we need to relax the "bubble" requirement. We need to make measurements of the space outside to observe the new universe happening. One approach would be to rely on purely quantum interactions which transfer no energy, but the best that's going to do is give us a probability of the bubble popping at any given time. We need to make real measurements. This means energy goes out of the bubble, and energy comes into the bubble. Now we are part of the universe, because we are interacting thermodynamically. One of the side effects of this is that we now apply thermodynamic laws, which state that energy will always transfer from the hot side to the cold side. The universe outside is the cold side, so energy will seep out. You are now playing a game of Russian Roulette: will a random universe appear outside before the same forces that make random universes tear apart your bubble. As I mentioned in my previous answer, there is a solution to this. Consider survival not as a pass/fail thing, but a metric. Zero survival is "no information stored in the bubble when it was sealed survives," maximum survival is "all information stored in the bubble when it was sealed survives," and the metric in between captures how much of the important information you keep. This forces you to understand what you actually want to keep and what you are willing to lose. Over time, you sacrifice the lower value information to provide the energy needed to do measurements of the universe. If you use an amount of power proportional to the energy you have stored, the pattern works. At first you lose more energy than you gain information, because nothing interesting has happened. As you continue, you expend less and less energy, exponentially. Such a curve only ends when you run out of bits of entropy. As long as you expend a small enough amount of power, you can let the heat death of the universe outrace you, and wait for the new begining. The limit of this is when you run out of bits of entropy. When you only have 1 bit of entropy left, you cannot subdivide it. Or can you? What if we reframe the metric. What if the metric permitted fractional bits of entropy. A fractional bit of entropy could not cause a bit flip from 0 to 1. However, if the universe that is reborn also has some constructs which can be described as having fractional bits of energy. We might be able to influence the new universe, even if we can't provably flip a bit from 0 to 1. How could this work? We went to two extremes. Quantum interactions provided no classical information to decide when to pop the bubble. Classical measurements provided that information, but had entropic costs. What about in between? There is some recent development in [Weak Measurement](https://en.wikipedia.org/wiki/Weak_measurement), which is a QM approach to gathering information about a system while learning much less about the average state of the system than usual. For example, consider a case of polarization. We are used to measuring photons classically to determine horizontal or vertical polarization. We are used to measuring photons with pure quantum entanglement, but that doesn't generate any information. Weak measurement provides results like "There is a 10 degree difference in polarization angle between the measured photon and the photon you just weakly entangled with it." You still don't know much about the angle, but you know a way to calculate it. This approach can permit measurements which have the appearance of a fractional bit of entropy associated with them. This is demonstrated for such QM operators using the "gentle measurement lemma." This suggests that, through weak measurement of the dying universe around you, you could interact with the world, peering out for a new universe. Once you see that new universe, you could influence it using weak measurements to make sure every fractional bit of entropy you saved gets its maximum impact. And, if you got lucky, and the new universe spawned early, you might even make the choice to classically measure whether the new universe has formed, at the expense of energy. If successful, you could even interact classically with that universe. Construction of this is the tricky part. In particular, it is impossible to prove that it will work using modern mathematics. To ensure the power used is proportional to the energy in the bubble, your bubble making engine needs to "know" how much energy there is. However, to do that, it needs to know how much energy is in the energy knowing system, and so forth. As it turns out, modern set theory has an axiom, the [Axiom of Regularity](https://en.wikipedia.org/wiki/Axiom_of_regularity), which forbids such self-referential structures. You would have to use one of the alternative set theories that are being developed which permit [urelements](https://en.wikipedia.org/wiki/Urelement) such as Quine atoms, and then you'd need to go make sure your scientific theories do not fall apart in such systems (such set theories are not "well founded" which has some pesky consequences). In the end, you may be able to do it, but using existing math and science it would be impossible to prove that the bubble you constructed will do the job, with 100% success. You'll always have some uncertainty. But, perhaps, when dealing with the certainty of heat death, maybe we can accept not knowing the future in exchange for avoiding a known undesirable fate. [Answer] "Surviving" heat death is not a small task. Not small at all. In fact, not only are there fiction writers who talk about it, such as Stephen Baxter's Manifold Time, there are in fact philosophers who discuss it. Nietzsche wrote about "The Last Man" in Thus Spoke Zarathustra. The Last Man was a society whose sole goal was the continued persistence of their society. Zarathustra loudly decried this, for you need some goal deeper than just continuing. To survive this long, we need to think in terms of information. What information survives. Our bodies don't stand a chance. When you're talking about proton decay, the concept of a modern H. sapiens body surviving is utter lunacy. However, we could become something which is closer to the ideal concept of information. If we thought that way, our goal is to preserve the information that makes us 'us.' We have to preserve it while the media we store that information in slowly degrades from heat death. If we can measure how much energy we have stored up, and spend an amount of power proportional to that energy in maintaining information, such as correcting bit errors due to degradation, there is theoretically no limit as to how long one can persist. The hard part is how to do that for long periods of time. You basically have to create a heat engine which "evaporates" the outer layers of your ordered structure of information to provide the energy needed to maintain the core information. It's actually remarkably similar to evaporative cooling, just at an information theoretic level. The effective limit of this process is when you can no longer maintain the proportionality of energy stored vs. power consumed. At some point, you may hit quantization issues where you simply cannot make your bits any lower energy than they already are, and you cannot afford the energy expenditure to correct them. The key to this process is that Wikipedia is wrong. The odds of quantum physics remaining the most accurate model of how our universe works for the next $10^{10^{56}}$ years is pretty darn close to zero. We will find a more valid model, and at that time we will want to adapt our survival process to match whatever new discovery we have. For all we know, if you carefully arrange quarks into a row to write out ↑↑↓↓←→←→BA, maybe the universe will provide a way to violate conservation of energy. Or maybe we finally find out what the ingredients are in this pill, and take the next step: [![enter image description here](https://i.stack.imgur.com/A9gOzm.jpg)](https://i.stack.imgur.com/A9gOzm.jpg) [Answer] The heat death of the universe is predicated on the idea that it is a [closed universe](https://en.wikipedia.org/wiki/Heat_death_of_the_universe). Therefore the conservation of energy and the arrow of entropy dominate. But we live in an [expanding universe](https://en.wikipedia.org/wiki/Metric_expansion_of_space), an accelerating expansion at that. Given that space actually has [energy](https://en.wikipedia.org/wiki/Vacuum_energy) associated with it, where is [the energy coming from](https://physics.stackexchange.com/questions/296/is-energy-really-conserved)? Of course there is dark energy, and many believe that this implies [additional energy is being created](http://www.preposterousuniverse.com/blog/2010/02/22/energy-is-not-conserved/). So if one could find and [tap that source](http://articles.adsabs.harvard.edu//full/1995ApJ...446...63H/0000063.000.html)... [Answer] And while you're waiting it out what is going to protect your equipment? The same forces that have ravaged the universe will ravage your own equipment, it's going to decay away. [Answer] <http://crowlspace.com/?p=1118> is quite an interesting read. Basically it combines 2 theories, one that black holes could survive a big crunch, and another that aliens could live inside the event horizon of charged, rotating black holes. Of course the aliens would be trapped, until some unwitting explorers entered with their ftl spaceships, giving you honest to god Cthulhu. Of course, you are asking for what would happen in a heat death. The wikipedia article <https://en.wikipedia.org/wiki/Hawking_radiation> for Hawking radiation states a black hole lasts before evaporating for a time [![enter image description here](https://i.stack.imgur.com/G2QHX.png)](https://i.stack.imgur.com/G2QHX.png) so you need this time to be at least 10^10^56 years, and then the aliens can use their alcubierre drives or whatever to escape the event horizon. Of course, this puts the mass needed at 10^10^55 kg, several billion times larger than the mass of the universe. Of course models of the universe including more dimensions, and having the black hole spinning and charged could adjust this mass to a more favourable amount. ]
[Question] [ Let there be an Intelligent alien species of heavily armored but lightly armed folks. Think of sentient crabs without claws. The are physically incapable of fighting each other. They are filter feeders but because of the complexity of their ecosystem, this means a lot of thinking and moving around to maximize feeding but when the food is found there is more available than possible for even a huge group to consume it all. They sexually reproduce by releasing milt and eggs into the ocean. So have I covered all the bases? Is there a method I have missed where they can consciously compete? Of course, sperm and egg competition and longevity are going on but I am looking for direct modes of conflict that are apparent to the individual. [Answer] ## No. One case study of an organism that initially don't compete with each other significantly during large, sudden phases of food abundance is the [hagfish](https://en.wikipedia.org/wiki/Hagfish), which generally lives in a food-poor environment on the ocean floor. During a [whalefall](http://discovermagazine.com/2013/september/16-deep-sea-secrets), however, they have access to a near-unlimited amount of food which outweighs them by millions of times. Even in such cases of abundant food, the hagfish often compete with each other for food, especially when the food [becomes depleted (video)](https://youtu.be/vQbGk4sHROg?t=35) after long periods of feeding. Food sources are finite, and given enough time there would be sufficiently little food left behind for competition to begin. Competition is fundamental to biology. Any biological organism has a certain fitness, and organisms that have lower fitness would be outcompeted by higher fitness ones through the processes of natural selection. In fact, Thomas Malthus described the fundamental instability of such initially competition-free systems in the 18th century. [A Malthusian catastrophe](https://en.wikipedia.org/wiki/Malthusian_catastrophe) occurs when population growth (a fundamentally exponential process) outpaces the growth of available food resources (a fundamentally linear process). Malthus wrote: > > Famine seems to be the last, the most dreadful resource of nature. The > power of population is so superior to the power of the earth to > produce subsistence for man, that premature death must in some shape > or other visit the human race. The vices of mankind are active and > able ministers of depopulation. They are the precursors in the great > army of destruction, and often finish the dreadful work themselves. > But should they fail in this war of extermination, sickly seasons, > epidemics, pestilence, and plague advance in terrific array, and sweep > off their thousands and tens of thousands. Should success be still > incomplete, gigantic inevitable famine stalks in the rear, and with > one mighty blow levels the population with the food of the world. > > > Famine would inevitably result when exponential population growth results in there being insufficient food to feed all of the organisms. It may be possible for some organisms to evolve birth control, but these organisms would have a lower birth rate and therefore a lower fitness. They would be quickly outcompeted by organisms which do not utilise birth control and maximally utilise the food sources to reproduce. The result is a [tragedy of the commons](https://en.wikipedia.org/wiki/Tragedy_of_the_commons), where the organisms breed themselves into starvation. [Answer] If you widen the definitions, you'll find the definitions of competition get very blurry, but if we're holding ourselves to a strict communal behavior without competition, one could look at ants or termites or bees. Within the colony itself, there is no competition (that I am aware of), but they are absolutely a society. [Answer] There will always be limited resources because a species will expand to absorb what is available. For example, you say "but when the food is found there is more available than possible for even a huge group to consume it all". So what stops them from having more offspring until the group is huger than huge and can consume so much of it that it becomes worth fighting for access? "They sexually reproduce by releasing milt and eggs into the ocean." What prevents some males from boxing out other males from the portion of the ocean where the females are releasing their eggs? What prevents females from maneuvering for position close to the strongest males? Are their predators around? One of your creatures might find that when it is time to escape one gets a slight advantage by cutting off another of your creatures so that the predator catches the other and stops pursuit. Living beings compete. That's how evolution works. Even plants do it both physically (e.g. growing taller to get the sunlight) and chemically (read up on it - I don't know the details). [Answer] ## For sentient beings it's about culture, not physiology In order to allow two creatures to fight you need: 1. A physical possibility of harming each other 2. A mental possibility to do this Point one isn't really a problem for intelligent beings, regardless of how armored they are. They still can use weapons, traps, poisons, sticks and stones, everything that can harm their brothers, unless they are completely invincible (but from your description I conclude they aren't). If they can't kill each other, they might hurt, deceive, abridge each other's freedom, etc. On the other hand, if the culture itself leave no space for violence, it's representatives will never go fight each other. They just won't have reason to do this. ## Apart from food and reproduction, there are more to compete for Beliefs. Scientific discoveries. Maps. Precious metals. Territory. Influence. Athletic feats. Anything the current culture counts as valuable. ## To compete doesn't always mean to fight each other Athletes compare their physical possibilities. Hunters and fishermen compare their catch. Builders compare their creations. Artists fight for audience. Leaders need their followers. There is always space for competition. [Answer] No. There will always be competition. You may be able to bring in periods of time where there is abundant food so no competition for that but the abundance will not last for ever. Once food starts to run low competition will become fierce for what remains with those who lose the competition being forced to set out in search of new food sources. This is inevitable as competition to breed the most will be happening while food is abundant causing a population explosion followed by a crash when it runs out. This will give you two phases: reproductive competition during times of feast, followed by resource competition during times of famine. There will also be competition to transition between those times. [Answer] You seem to be trying to set up an environment that doesn't have ANY evolutionary pressures. Competition in evolutionary terms encompasses much more than beast vs beast. Better resistance to disease, or being more attractive, or fertile, or having keener senses,... That said I may be wrong and you are just wanting to determine if a society can evolve that has no interest in or benefit from direct competition. Well, even in your scenario the population will expand to the limits of the most critical resource (even if it's a huge amount!) Those members of the population with variations that give them any advantage will resemble he status quo less and less. Divergence and thus evolution is inevitable. [Answer] ## Maybe It depends on your creatures. If they have a hive mind, like bees or ants, then yes. Otherwise, no. The will likely try their best to survive, and while it may not be competition by your standards, there will still be some doing Bette than others, and others trying to do better. They may not be able to harm each other directly, but they can still do so indirectly. The strongest will go to the best places, and nudge the weaker ones out. Things like that. ]
[Question] [ I have a few questions related to a crazy setting I'm working for my novel. Let's say we have a planet with a thin atmosphere and low gravity. It's volcanic activity is so intense that the planet has turned into hell, basically—even entire volcanic belts go off with very (read VERY) powerful eruptions. The questions are: * Considering we have a low gravity and a thin atmosphere, can these eruptions throw volcanic material into space (even large rocks)? * Considering that these eruptions happen very frequently, how feasible is that a cloud of debris could form around the planet (even completely covering it)? The material might plummet back to the surface, but get replenished by new eruptions. I know it sounds kind of crazy, but I want to build a hell of a world for a chapter. Am I pushing the boundaries of believability too far? [Answer] Maybe. You don't given any details of your planet re: how thin the atmosphere really is, and what is the required escape velocity (or the details that would allow its calculation). [Ejecta velocities, magma chamber pressure and kinetic energy associated with the 1968 eruption of Arenal Volcano](http://link.springer.com/article/10.1007%2FBF02596963) suggest the eruption velocities could reach as much as 2 km/sec. This would be sufficient to achieve lunar orbit. If the moon has significant air drag, orbit would not be possible though. You want high vulcanism, but presumably not enough to destroy to the planet. Yet you also need a low escape velocity and no (if possible) or very thin atmosphere. Put your planet in near orbit of a gas giant to cause lots of tidal heating in the core, or you could just have a lot of uranium and thorium in the core compared to Earth. If you need a breathable atmosphere but thin as possible, make the atmosphere essentially pure oxygen with a trace of CO2 at about 0.2 atmosphere of pressure (your planet will be a little oxygen deficient compared to Earth, but quite breathable). Now, make your vulcanism primarily due to an extremely powerful and very tall volcano or chain to get the "launch point" above most of the atmosphere. Due to the lower gravity, you may be able to make the volcano 30 km high, maybe even a little more. Granite flows downhill under sufficient pressure given time, so there is a limit to how tall a mountain can be. At this point you can make the orbital volcano ejecta believable if not entirely realistic. Keeping a breathable atmosphere might be hard to explain - perhaps oxygen was unusually abundant originally and it is still seeping out from the interior. Still needs to be larger than the moon to keep an atmosphere, probably Mars size would be needed in addition to the ongoing replacement of oxygen. --- When I read your question, I thought you were interested in a thick orbital cloud. Now I think you are talking about an atmospheric cloud. Re: Having a thick volcanic clouds within the atmosphere it is not necessary at all. Large volcanic plume have been seen on Earth up to 50 miles above the surface. This is primarily a result of the warm air rising. To keep a consistent cloud, the vulcanism would have to be ongoing. Historical heavy eruptions on Earth only generate a cloud dense enough to obscure for a fairly short duration (weeks or months) and never world-wide. Even a super-volcano such as Yellowstone is not expected to cloud over the whole planet. To keep cloud duration high you actually are better off with a thick atmosphere, which is very hard to justify on a small planet, and it makes orbital insertion impossible. A possible solution to keeping a dark sky that is a result of vulcanism is to add biology into the mix. Say that these is a common bacteria adapted to using the volcanic material in the atmosphere. The bacteria consume this and eliminates the waste as microscopic particles of soot. This type of soot could remain in the atmosphere for many years if no rain, etc. washes it out. A number of earth bacteria are sulfur based, it is not inconceivable that a bacteria could consume sulphur and CO2 and end up expelling tiny soot particles. Alternatively, you could have a high carbon planet, and carbon or hydrocarbons are a large component of the hot volcanic exhaust. If these burn incompletely you get soot. These soot particle will not generally be small enough to stay in the atmosphere for years, so this would be considerable less effective in generating permanent dark clouds. --- Since you don't need a breathable atmosphere at all, and you apparently want the cloud to be orbital, you don't want any atmosphere at all. Any atmosphere will cause drag in low orbit, so get rid of the atmosphere. Forgot to mention you want to give your planet a fast spin to that the ejecta has a relatively large angular momentum. Only a small fraction of the ejecta will be able to stay in orbit (as a result of secondary collisions) and it will tend to stay in concentrated in a band with a latitude roughly less than or equal to the latitude of the volcano. You minimum the orbital band thickness (along the north/south line) by placing your volcano near the equator. The natural tendency of the orbital rubble will be to form a ring, not a cloud. As the rubble interacts, it will naturally become of very thin orbital ring. This takes some time, and since your ejecta in continually renewing the ring, you could have essentially a ring with some thickness. There is no believable way to cover the whole planet, or even a large fraction of the planet. Since you don't need atmosphere, making the planet smaller will reduce the necessary orbital velocity too. However, this will also tend to reduce vulcanism, so you need even more uranium/thorium or tidal stress to generate vulcanism. Again, I am arguing that this answer is only plausible, not realistic. Your need to use as many of the circumstances I've mentioned to maximum the density of the orbital cloud and believability. [Answer] I think you are pushing the boundary of believability a little too far, at least for someone who is somewhat familiar with orbital mechanics. (That may or may not be a problem for your intended audience.) Space isn't high up, like: [![Yay! Space!](https://i.stack.imgur.com/TAry1.png)](https://what-if.xkcd.com/58/) Space is fast, [like](https://what-if.xkcd.com/58/): [![Space isn't high up, it's fast.](https://what-if.xkcd.com/imgs/a/58/orbit_wide.png)](https://what-if.xkcd.com/58/) Now, in principle, you could get around this by having your volcanic eruptions take place at an angle somehow (not sure how realistic that is), but just tossing material straight up will have one of two outcomes: * It will reach [escape velocity](https://en.wikipedia.org/wiki/Escape_velocity) and leave the planet's sphere of influence. It may still remain in a relevant orbit, like how you can gain enough velocity to break free of Earth's gravity only to find yourself still stuck in the Sun's gravity well. * It will fail to reach escape velocity, and simply fall back down. In this case, the object will likely trace approximately a ballistic trajectory. Keep in mind that in low Earth orbit, despite apparent weightlessness, [gravity is about 90% of that on the surface](http://scienceline.ucsb.edu/getkey.php?key=4623). The only reason why a satellite doesn't simply fall down is that the launch has imparted a great (approximately 7,000 m/s or more, in the case of the Earth) forward velocity. This forward velocity exactly (to within small error) compensates for the downward pull effected by the gravity of the Earth, in any given orbit. Compare for example [Why is geosynchronous orbit an altitude, rather than a velocity?](https://space.stackexchange.com/q/10860/415) over on Space Exploration SE, or more generally [their orbital-mechanics tag](https://space.stackexchange.com/questions/tagged/orbital-mechanics). As others have already pointed out, absent additional energy inputs, [orbits are closed](https://worldbuilding.stackexchange.com/a/31403/29), which means you can't toss material into an orbit. However, with suitably lucky atmospheric skips and low enough gravity, it just might be possible to toss material at an angle that eventually results into a (most likely highly elliptic) orbit. Such material would likely need to be launched at angles that are almost parallell to the ground, and obviously with sufficient velocity to maintain orbital velocity at orbital altitudes. # An alternative solution: However, this might be easy to work around without altering your setting too much. You stated in a comment that: > > In my novel, a crew sails through the clouds of such a planet and find a spacecraft wreckage containing some important information for the rest of the plot. Some people said it wasn't believable since such clouds are just impossible to form without the debris accreting into a disc, like Saturn. > > > (This has the added problem that such a "cloud" would create drag, which will quickly cause anything caught in it to deorbit. Even [the ISS](https://en.wikipedia.org/wiki/International_Space_Station) experiences [drag](https://en.wikipedia.org/wiki/International_Space_Station#Power_and_thermal_control) and needs periodic reboosts to [maintain](https://space.stackexchange.com/a/9512/415) its approximately 400 km high orbit.) Consider instead of making this a natural phenomenon, simply making it an extreme runaway case of [space debris](https://space.stackexchange.com/q/19/415), known as [the Kessler syndrome or effect](https://en.wikipedia.org/wiki/Kessler_syndrome). Have the timing reasonably right, and it's plausible for a spacecraft to be disabled by space debris but not yet destroyed by it when your crew comes along. [Answer] No. Gary Walker missed a critical point. Under extreme conditions you might be able to get a volcano to eject material at orbital velocities from a small world. This does not mean it can toss debris into orbit, though. One basic truism of orbital mechanics is that (barring precession and the like) an orbit intersects the last point the object was accelerated. Thus if your supervolcano throws a rock at orbital velocity it goes around the planet--but then smacks back into the volcano at the same angle as it left the volcano in the first place. If you have any atmosphere the problem is even worse, it must fall short. Edit: Argh, I got the sign backwards. It's the same angle all right--if it leaves at 10 degrees above the horizon it returns at -10 degrees above the horizon--that is, it falls short. The only way to even hit the volcano is with an ejection angle of zero. Note that this does not say a volcano can't eject rocks at escape velocity. Those rocks won't come back and hit the world but neither will they stay in orbit around it. [Answer] The best place in the Solar System to see the effects you want would be Io, orbiting Jupiter. [![Io](https://i.stack.imgur.com/eiX3g.jpg)](https://i.stack.imgur.com/eiX3g.jpg) Io is truly a hellish place, with the most active vulcanism in the entire Solar System, and being a small moon, the sulphur and sulphides ejected from the volcanic activity routinely makes it into space. Io orbits Jupiter surrounded by a torus of sulphur ions (Jupiter's massive radiation belts and the two trillion watt "flux tube" between Jupiter and Io see to that). A spacecraft operating in or near Io's orbit will probably be coated in sulphur dust very quickly, in addition to being irradiated by the Jovian belts. Somewhat more benign environments can be found around ice moons orbiting Jupiter and Saturn, where giant geysers can eject water vapour and ice particles into the space surrounding the moon. for various reasons, this isn't as intense as Io's vulcanism, but if the moon was closer to the primary, the extra energy from gravitational "kneading" might supply the force needed to put a truly impressive amount of water into orbit (once again, a fairly diffuse torus once it is spread around the orbit of the moon, but still enough to interfere with spacecraft operations). The debris in orbit will follow power law distribution, so the bulk of the material will be gasses and ions, followed by simple molecules, then dust and so on down the line. The amount of energy needed to throw large boulders into orbit would also result in really vast clouds of dust and even larger amounts of gasses being ejected into space, possibly enough to make spacecraft operation completely impossible (moving into a dust cloud at interplanetary velocity would probably destroy the spacecraft). Enjoy the ride. [Answer] Expanding upon part of Michael Kjorling's answer: Kessler Syndrome requires a technological civilization putting a bunch of stuff in orbit to come apart and make the orbital space into a debris cloud. However, for the purposes of providing a deadly orbital hazard there's another approach: Your planet recently ate a moon. This will happen when the moon has an orbital period of less than a day--it will slowly spiral in and eventually pass within the Roche limit of the planet. How much farther in it will survive depends on how tough it is. (Something very strong survives to atmosphere, a gravel pile starts coming apart as soon as it crosses the line.) Once it fails it comes apart into a bunch of debris something like the rings of Saturn. While this is only a ring and not the whole orbital space there's no safe orbit short of not being at those altitudes in the first place. (And, yes, this was a scary thing for Casssini when it had to make a passage through the rings. They aimed for a gap but they knew there was a chance they would lose the probe.) Look to Mars. This will be the eventual fate of Phobos. It's spiraling in and already showing the strain. (The exact failure point can't be determined without knowing it's density and strength. If it were liquid it would already be a goner.) ]
[Question] [ Today mankind rely on food's refrigeration and heating to produce in large scale and be fed. This only works because high and low temperature in processes like UHT and others kill most of bacteria and other microorganisms. And storing food at low temperatures slows bacterial growth. However given tens of thousands of years of Earth's and humanity's lots of those organisms could adapt to be able to survive and reproduce faster in high and low temperatures, making it impracticable to use refrigerators to store and transport food, and freezing and boiling things to kill microorganisms. How would the society organize to feed the entire population then? [Answer] From [here](http://food-drink.blurtit.com/18994/how-does-a-refrigerator-keep-food-fresh), bacteria needs four things to grow. Also note [this wiki article](https://en.wikipedia.org/wiki/Food_preservation) that I got a lot of links from to use below. 1. Correct temperature. Note that in order to survive in extreme temperatures, the extremophile bacteria obviously needs to be different from normal bacteria. The more different it is, the more likely it becomes that the new bacteria "eats" stuff that isn't found at normal human temperatures. Point being, if you can't just boil it in a [pressure cooker](https://en.wikipedia.org/wiki/Pressure_cooking) (allows the water to get hotter than 100 °C) or kill it with [UHT](https://en.wikipedia.org/wiki/Ultra-high-temperature_processing) (ultra-high-temp processing), it probably wasn't that dangerous anyways. Similarly, if it normally thrives at -100 °C, it probably isn't used to water-based environments, so if you just get rid of whatever chemical it's used to, it dies. And most organic things probably don't have that chemical, so we're safe. So the simple answer is: For any bacteria that's still dangerous, we just freeze it a little colder and/or heat it a little hotter because there's still a finite limit on what temperatures the bacteria can live in. But maybe this bacteria is dangerous and survives at ranges so cold or hot you have to destroy the food to kill the bacteria. So we need other methods of ~~extermination~~ food preservation. 2. Correct pH levels. You can kill a lot of bacteria with acid, like vinegar, tomato juice, lemon juice, or lime juice. This is how salsas are often made so they can stay edible weeks after you opened them, and is a form of [pickling](https://en.wikipedia.org/wiki/Pickling). Acidity is one method of [fermentation](https://en.wikipedia.org/wiki/Fermentation_in_food_processing). The other method uses alcohol. Alternately, you can make the food too alkaline, using [lye](https://en.wikipedia.org/wiki/Lye). 3. Moisture. You can [dry food](https://en.wikipedia.org/wiki/Drying_%28food%29), which doesn't leave the bacteria any water to survive off of. [Salting](https://en.wikipedia.org/wiki/Salting_%28food%29) involves covering the food in salt, which absorbs the moisture nearby. Since salt is edible, we live, the bacteria don't. 4. Oxygen. You can [vacuum-seal](https://en.wikipedia.org/wiki/Vacuum_packing) food to starve bacteria of fresh oxygen. [Jellying](https://en.wikipedia.org/wiki/Aspic) a food keeps it fresh by starving bacteria of oxygen. [Smoking](https://en.wikipedia.org/wiki/Smoking_%28cooking%29) covers food with anti-oxidants, but normally doesn't penetrate into the food. So it's usually just a partial measure, and is used with another method. 5. Other Methods There are a lot of other methods, many listed on the wiki article I linked above. But here are some of the ones I found interesting. [Pascalization](https://en.wikipedia.org/wiki/Pascalization) involves putting the food under really high pressure. ("Pascal" is a guy who did a lot of work with, among other things, pressure, and is also a unit of pressure, so the name basically means "pressurization".) The pressures get up to thousands of times normal atmospheric pressure, and render the bacteria inert. [Irradiation](https://en.wikipedia.org/wiki/Food_irradiation) (yes, that kind of radiation) kills the bacteria the same way radiation kills humans, but doesn't make the food radioactive or harmful. It's not currently used a lot, but has been used in fruits and vegetables, meats, and spices. [Answer] Historically there are many more methods of conserving food: 1. Dry (milk powder) 2. Remove air (protective atmosphere - no oxygen or immerse in water or oil) 3. Pickle (like... pickles) 4. Controlled degradation or fermentation (Yoghurt, cheese) 5. Curing (with for example salt) I expect that drying and removing air will take over most of the heating&freezing methods we use today. Food speculation will slow and food in general will be more expensive. Reference: <http://www.thenewsurvivalist.com/> <https://en.wikipedia.org/wiki/Food_preservation> ]
[Question] [ In the near future, the last of the human race has been forced to retreat underground due to extreme global warming or some solar flare event. Vertical hydroponic farms provide the food for the survivors, but do not produce enough oxygen for breathing. The three most abundant minerals in the earth's crust are: 1. Oxygen 2. Silicon 3. Aluminum --- Oxygen composes around 460 000 molecules out of every million (ppm). This is around 46%. Assuming that the survivors have had time to prepare for the apocalypse, and have a state of the art facility in which to work. Would it be feasible for us to extract the bare elements from the crust? [Answer] ## Yes But I foresee two issues: 1) Crustal rocks will be deficient in a several elements more common on the surface of the Earth than occur in the rocks. The two most important of these are hydrogen and nitrogen. 2) Refining rocks into their constituent minerals or elements will require a great deal of energy. So you'll need powerful power generators. You'll also need some where to dump your waste heat from those generators. [Answer] Possible, but you're unlikely to need much of it. A vegetation capable of feeding a population would also generate enough oxygen to support it. Here's why. Humans and other animals use oxygen to [oxidize organic matter](https://en.wikipedia.org/wiki/Citric_acid_cycle) (i.e. food) into CO2 and H2O. On the other hand, plant use CO2 and H2O to [synthesize organic matter](https://en.wikipedia.org/wiki/Photosynthesis), and release O2 as a byproduct. So it can be written as ``` 1) CO2 + H2O + light -> food + O2↑ 2) food + O2 -> CO2↑ + H2O ``` No matter what real formula of food is and how you transform it, the O2 parity will hold. That said, some oxygen may be trapped in metal oxides, like rust. This will have to be replenished. Luckily enough, you'll still need metals (say Al and Fe) to keep the colony going. Those will have to be reduced from oxides, using up a lot of energy and again releasing O2 (or CO2, if you plan using current technology to make iron/steel, but then the plants will capture it) as a byproduct. Another thing mentioned in the comments is that you'll have to buffer CO2 somewhere, because [large CO2 concentrations are bad for humans](https://en.wikipedia.org/wiki/Hypercapnia). The present Earth uses ocean for that, limestone and similar rocks are another great buffer. But you don't have oceans at hand. Of course, you don't want to store CO2 indefinitely, but rather feed it to the plants. [Answer] It sounds possible. The most abundant mineral with oxygen in the earth's crust is silicon-dioxide (silica). The energy of the bond in this molecule is about 400kj/mol, so this is the amount of energy you need to expend to release one mole of 02 from silica. One mole of oxygen will last one person about 23 minutes of breathing. So one person will use 438 moles of oxygen per week. It takes 175,000 KJ of energy to make 438 moles of oxygen from silica. <http://www.bromicacid.com/lonelychemist/Questions/093008.htm> 175,000 KJ is equivalent to 6kg of coal. <http://www.kylesconverter.com/energy,-work,-and-heat/kilojoules-to-tons-of-coal-equivalent> So, one person needs to supply enough silica, plus 6kg of coal (or its equivalent) to use as energy to release enough oxygen to last them a week. I think its more likely you would want to treat the dirty air above you though. ]
[Question] [ > > [Researchers create a sonic tractor beam](http://news.sciencemag.org/physics/2015/10/researchers-create-sonic-tractor-beam?utm_campaign=email-news-latest&et_rid=17041797&et_cid=65559) > > > By Hanae Armitage 27 October 2015 1:00 pm > > > Using a simple set of loudspeakers, scientists have figured out a way > to levitate and rotate objects in midair. If perfected, this “sonic > tractor beam” could find uses ranging from treating kidney stones to > creating artificial gravity on the International Space Station. > > > That isn't going to work for my aliens when grabbing onto other spacecraft. There are no sound waves in space. How can they use electromagnetic or other physics to create their tractor beam? [Answer] Forget science articles from non serious science sources. They are misleading to say the least. Basic Science The two attractive forces that can work from distance are electromagnetism and gravity. So if you want any tractor beam you must use one or both. Unfortunately neither can be directed (as far as we know) and they "spread" in all directions meaning you cannot select a specific object and pull it. You will affect anything in range in the same way. Also gravity cannot be created (as far as we know). An electromagnetic field can be created by an electric current. So a tractor beam is most likely to be a big electromagnet. Electromagnet attraction [doesn't work on everything](https://physics.stackexchange.com/questions/15747/how-strong-of-magnetic-field-would-noticibly-attract-a-person). Also you will need a lot of energy to create a strong enough effect. In space note that your ship attracting another object will make both to move as by [Newton's third law](https://en.wikipedia.org/wiki/Newton%27s_laws_of_motion). Finally consider that if you need to grab something in space to your spaceship it can be a lot easier just to use some kind of "crane". The means to attach to the target can be by harpoon (but can damage the target), suction (very hard in space without an atmosphere and also needs a smooth target surface) or electromagnets (needs a iron-like object and can damage/impair sensible electronics) The next cool option Maybe a good and cool option is to use space drones. A swarm of small rocket robots can move far away from your spaceship and grab things for you. But remember it's not that easy to move a complex object like ISS without it starting to rotate and derive in funny ways. [Laser pulling particles](https://en.wikipedia.org/wiki/Tractor_beam) There are some claims in that but let's read it carefully. Those devices work by heating one side of the particle so air in contact with that particles ascends and this movement pulls the particle (like a miniature vacuum). It don't works in space and is limited to very small targets. A bigger laser to move a big object is more likely to use enough energy to burn it. [![To pull or to push from the other side?](https://i.stack.imgur.com/e3KFC.jpg)](https://i.stack.imgur.com/e3KFC.jpg) Note: high potency lasers work by just reducing its pulse duration to a fraction of second. The shorter the pulse, the higher the potency using the same energy amount. This means to continuously fire a high potency laser needs a huge amount of energy [Answer] Shoot sticky electrically charged goo towards the object you want, and use the opposite charge to attract it. This is somewhat doable, but for any realistic masses and charges you will have a problem making the goo not to disintegrate because of the charge it contains. So realistically this will work only on rather light objects not far away (certainly not astronomical distances). [Answer] If the aliens have artificial gravity inside their ships, they should be able to focus fields from a gravity generator outside the ship to manipulate objects within some distance. The larger the other item and the farther away it is, the greater the energy needed to do so. If the other ship has engines, if it turned them on, then both ships would move, the 'tractor' beam would still only work on the relative frames of the two ships. To fulfill the 'hard science' I'll add this. the 'tractor beam' would be a special harpoon with a head depleted uranium to penetrate the hull and carbon nano-filament cable to 'pull' the ships together... [Answer] The goal of a tractor beam.. * To bring distance objects to your position, without requiring you to move (or with the least effort possible) --- While the article you linked is very interesting, I did notice that the one side their speakers were on is the bottom of the object. I'm curious if it could also make the object levitate if the speakers were above, because then it would be "pulling" the object, rather than just not "pushing" as much and allowing gravity to bring it back towards the speakers. In space, you could easily create "pushing" pulses with launched explosives. *Or maybe a tiny laser with enough energy to break a single bond on the other objects surface (also resulting in an explosion)* Tons of "tiny" explosions could push an object and rotate it however you'd like. But, like I suspect the acoustic tractor beam works, it probably can't pull anything towards you very well. Obviously, depending on the object, most spacecraft would be annihilated with this strategy - but if you had, for instance, some kind of sci-fi futuristic shielding or armor, it might be plausible. (More realistically, you could also achieve a similar effect by hitting them with many projectiles: but, similar to the explosions, I don't know of a way the projectiles could transfer their velocity without damaging the target. You also have to worry about pushing yourself backwards!) --- That leaves other strategies, which accomplish the goal but aren't really considered "tractor beams". In addition to other answers, (which at this point includes harpoons, drones, and goo+magnets), you may consider using a net or bola-like device which could wrap around the target. If the weights on your net had the propulsion mechanism necessary, it could pull the target to you and work across vast distances (as long as you hit them and it has enough fuel) - otherwise you're stuck using a "rope" (it'd actually have to be something light-weight and strong) which would cause the net to have a worse maximum range, plus require your ship to "pull" them in - which is probably pulling yourself just as much. [Answer] My honest advice would be don't explain it. In truth justifying a tractor beam existing with hard science is very hard, and further more any technology that makes it possible would likely have other uses, meaning you would then have to expand your world to include all the other technologies that would invariably come from the first. However, one of the cool things about science fiction is you get a certain free reign to say 'scientists invented it and it works like X', and so long as you don't violate any obvious hard constants of the world, most noticably in this case conservation of energy, you get allot of leaway to say it works because of principles that we just haven't discovered and trust me on this, so long as you [set clear rules](http://tvtropes.org/pmwiki/pmwiki.php/Main/MinovskyPhysics?from=Main.MinovskyParticle) and [stay consistent to them](http://tvtropes.org/pmwiki/pmwiki.php/Main/MagicAisMagicA). Trying to justify the science with hard facts is something I don't suggest trying unless you have very strong physics skill, because otherwise your likely to get part of the science wrong when explaining the technology and end up with a situation where the obvious flaws with the science [just make it more obvious that the technology doesn't make sense](http://tvtropes.org/pmwiki/pmwiki.php/Main/VoodooShark) However, that's writing advice, not world building advice so moving on... If you want to justify this the best explination I can suggest is gravity manipulation. Some method of shaping gravity was created such that you can create a strong gravity field which projects outwards from your ship, making objects 'fall' towards you. This works much better if your tractor beam can only pull, not push, objects, though with only a bit softer science you could probably handwave by saing you can manipulate gravity enough to create limited pushing effect. This works best because it's drawing on a basic force of nature which already does what you want, and gravitons and gravity in general still is not entirely understood on a full quantum level, making it at least mildly possible that creating of gravitons may be somehow possible. Though already my mind is throwing up questions as to how this would work that I don't think about if someone just says "we have a tractor beam" without justifying it as gravity. In short this is the best answer I can think of, but I still advice against not giving any. If you do have the ability to manipulate gravity you know have short range weapons to crush ships, potentially shields to deflect projectiles (depending on how much control you have of gravity), anti gravity ships that can 'float' at high speeds through the air of any planet, and of course artificial gravity for your ships, to name but a few related technologies that come from this. To minimize the questions people ask I would suggest saying that gravity is created only through a process like nuclear annihilation, or that you can only shape gravity but not create it, to justify the fact that only massive ships can manipulate gravity, to avoid question as to why small scale gravity manipulation isn't used for technology X. Also keep in mind that whatever technology you create your need to abide by conservation of energy. Moving anything large, like an astroid, in space means applying a massive force to it, which in turn means a massive energy expenditure. Your want to think about just how much energy your spending to move objects, and rather the ship engaging the tractor beam has that much energy readily available to expend (suggesting an order of magnitude more energy then the tractor beam used is available to it). It's easily possible to explain that ships do have that much energy available, but keep in mind just how massive energy that is and what someone can do with that much stored power. Any ship with that much power is capable of being quite lethal to anything around it if it transfers enough energy rapidly enough, just for starters. [Answer] If you don't mind becoming really freaky science wise, make the tractor beam be several beams of exotic particles that generate negative mass then the streams collide. The negative mass should be able to cause space-time distortions much like a warp drive and carry the entire section of spacetime, ship included, towards any direction you wish. [Answer] Its probably worth noting that Star Trek Enterprise used a fairly primitive form of tractor "beam", the grappling hook. Just fire that thing at your foe and drag them around like a jerk. If I was to imagine however what a real one would like, I'd assume that in our space future we have some sort of FTL going, and the only feasible way to do that would be something along the lines of the Alcubierre warp drive idea, where you make space in front of the ship less dense, and the space behind it more dense thus pushing a pocket of space containing the spaceship along. I think you can see where I'm going here. If you could do that, then I see no reason you couldn't make a tractor "beam" that creates a low density of space between you and the object pulling you and the object together. The best part of this is that you get to ignore a whole bunch of messy physics like newtons second law, because your not ACTUALLY pulling things together, just reducing the space between them. All it needs is a whole heckload of negative energy unobtanium. ]
[Question] [ What would the implications be for a humanoid species to excrete only gaseous waste from themselves instead of solid or liquid waste? Public bathroom facilities would not be needed, but how would this effect the original evolution of the species, and assuming it evolved to a current day human race what would be different? [Answer] I think the only answer is "they wouldn't be human." It's only reasonable to excrete gas if you either consume an incredibly small amount of matter, or limit yourself to consuming only gasses. The density of air is 1.225 kg/m^3. This means, at 1/3kg of food per day, we'd have to exude about a quarter cubic meter (~250L) of gas in the ultra-idealistic case. So, the first thing this goes to show is that the concept of bathrooms vanishes entirely, because you must be constantly exuding waste. However, there's a problem. That's assuming you just turn the food straight into gas. Some foods seem to be easy to do that to (I'm looking at you, evil microbes in my gut making me bloat), but a lot of things are simply not easy to break down into gas. You may need to bring in 4-5 times as much gas to combine with these foodstuffs to turn them into gas, raising the amount of gaseous output dramatically. It also starts to become very energy inefficient. How would you like to consume a morsel of food, only to find that it's going to take more energy to expel it than you got from the food? Now, perspective. 250L is a lot. Its about equivalent to how much we exhale in 35 minutes. If I have to multiply this by 4-5x, you're starting to see large volumes of gas movement dedicated to this effort. Also, much of that air volume is things like nitrogen, that are really had to use in a chemical process. Consider oxygen as a key reagent we might need, at 21% of the atmosphere. Now we have a need for 5x more gas flow, because we're only using 1/5th of it. Now 3 hours of your daily breathing has to go just to the mass dedicated to gasifying waste, in an ideal case, ignoring the need to burn fuel to do so. You'd certainly watch what you eat. Also consider that we have other "excretements" as well, when you start getting down to the dirty side of it. We exude skin cells on a constant basis. You might be able to be sneaky and just piggy-back on that process. If I were to find a creature that could do this, and ignored the challenge of explaining why it was evolutionary beneficial to limit onesself in such a way, it would be a massive flyer, with a high bypass airflow past its lungs, which would double as a stomach. Just like baleen wales, they'd captrue the little bit of matter they can't get from the air by snaring smaller bugs, and using their bodies. Its waste could be limited to cells shedding off the edges. [Answer] This depends on what gas they are excreting. If their metabolism is perfect or near-perfect then the gases would contain completely oxidized products such as sulphur dioxide, carbon dioxide, phosphorous pentoxide etc. It happens most of these gases have a strong greenhouse effect. In the absence of a cycle reconverting those gases into solid products, we (humans) are going to make Earth a planetary hell like Venus. Furthermore, the diet would be very very different and so would be the digestive system. I am expecting a predominantly herbivorous diet with a herbivore-mammalian-like digestive system (with multi-chambered stomach and huge appendix etc). It would not change the evolutionary history much anyway. I don't think shit has had a major role in human evolution. Environmental effects would be immense and are already discussed above. [Answer] Human waste didn't really become a large issue until we had large cities. At which point sanitation became an important part of city planning. Humans have not really evolved much in the last 2000 years where sanitation makes a difference in the health and survivability of individuals to procreation age. The big things would be what kind of biology has evolved with these people that handle turning the human waste back into biological mater? Right now everything recycles and much of it pretty rapidly. One of the big things would be scent would be much more important to these creatures not living in cities, since it is likely that many other animals are going to have similar digestive systems and being able to recognize their scents will have to replace spotting their spore. In Cities, scent will be down played, since it will stink even more, or cities will be spread out a lot more allowing for better 'ventilation'. Quite likely 'bathrooms' will be 'gardens' of plants that utilize the 'fertilizer' the most efficiently, and give off pleasant smells. [Answer] The evolutionary implications will be huge compared to H. Sapiens because so much of our body is devoted to handling wastes. Our bowels and urinary tract are specifically built to handle wastes. Lacking a solid and liquid waste system may be a disadvantage because if the body is only able to eliminate gaseous waste then what happens when it needs to flush a solid or liquid contaminant or toxin? Gas only wastes are unlikely since eventually, every terrestrial creature is going to eat dirt or something similar that simply will not, under any circumstances digest. Or, it will digest but at temperatures far in excess of what the creature can generate. That dirt has to go somewhere. Likewise, what will you do with excess solvent, such as water or ammonia? Or is the organism completely contained and doesn't need to consume a solvent except in very limited quantities? How does sweating work? Does this organism cool itself? While it's a simple thing to say "let's make a human that excretes gas", the implications involved in the operation of such a metabolism rapidly pushes a creature far away from human living habits. ]
[Question] [ Let's say that in my planetary system there is a gas giant around the size and distance from the Sun as Jupiter. I need the planet to be similar enough to earth to be able to be inhabited natural by humanoids. There are a few problems that I see with this below are the questions. * How do I keep the moon from becoming ice locked like Europa or Triton? I need it to be catch and keep enough heat to be habitable. * How do I protect the moon from both stellar radiation and the radiation of the gas giant? * How do I keep the orbit stable enough to avoid catastrophic failure? * How would the tides be affected by the gas giant (Assuming that they would be in the first place)? * How do I keep the temperature semi-regular to allow life to evolve? The closer to Earth you can make the moon the better. This question differs from: [Habitable moon of a gas giant: working out the sizes and distances](https://worldbuilding.stackexchange.com/questions/7270/habitable-moon-of-a-gas-giant-working-out-the-sizes-and-distances?rq=1) in that I am asking about atmosphere, radiation, stability, tides and tempurature not distance or size [Answer] Since you want this planet to be more or less Earth in orbit around a gas giant, let's do that, as a gedankenexperiment, and see what shakes out. * Currently, Earth is in the "Goldilocks Zone" of radiant energy from its star. too close and it would be too hot; too far, too cold ("too hot" and "too cold" generally having the bounds of the temperatures of liquid water). Mars is nominally inside the butter zone too, but too small to keep the necessary insulating atmosphere (that requires a planet between about 0.75 and 1.8 Earth masses); Venus is both a bit close and too insulating with the methane-heavy atmosphere. Jupiter is too far out, on the opposite side of the asteroid belt, but if our star were a bit larger and hotter, that would compensate. Additionally, Jupiter re-radiates quite a bit of the energy it absorbs from the Sun, which helps to warm its moons (not nearly enough, but it could help in a differently-arranged system elsewhere in the galaxy). * Earth is protected from most of the cosmic radiation our star emits in two ways. First, its magnetic field directs charged particles in the outer atmosphere toward the poles. The aurora borealis is the result of the Sun's emitted radiation collecting at the poles and its energy levels being moderated by the atmosphere to non-ionizing levels, producing visible light photons in the process. Second, the atmosphere itself and the ozone layer in the upper stratosphere moderate EMR in the lower ionizing levels of the near-ultraviolet spectrum, in a process that also makes the sky blue (known as Rayleigh scattering). * Every orbiting body of the Solar system by this point is pretty stable, including all of Jupiter's moons. There are some notable exceptions, a few comets and asteroids on highly elliptical orbits that haven't - yet - crossed paths with a planet, but the majority of the cataclysmic instabilities worked themselves out in the first few hundred million years of the Solar System's existence, and what's left is pure survivor bias. Any orbiting mass long-lived enough to produce a sentient race (or to be around long enough for humans to turn up) should be pretty safe. * The tides on our Earth-like moon of a gas giant would be significant but not destructive. The Earth-Moon mass ratio is about 6:1, and the orbital distance is around 450,000 km. The Jupiter-Earth mass difference is much larger, something like 315:1. However, Callisto, one of Jupiter's moons, orbits 1.8 million kilometers from Jupiter. Gravity, like most forces, follows the inverse-square law; all other things being equal, the magnitude of the force decreases on the square of the distance between particles on which the force is acting. The distance term, then, is critical to getting an Earth-like tidal balance using Jupiter instead of our Moon. An Earth-like planet orbiting at Callisto's distance might have even gentler tidal forces than Earth's. * Maintaining Earthlike ambient temperatures is a simple matter of making sure the orbiting body is close enough to the star to be warmed just the right amount to allow liquid surface water, then having an atmosphere with enough greenhouse gases to manage the temperature swing once you lose direct solar illumination of the surface. The big trick is going to be moving behind the gas giant. The most likely scenario is a highly off-eclipic orbit of our Earth-like moon, reducing the duration of time that the moon spends behind the giant relative to the sun. It would still get pretty chilly; for a few Earth weeks or months every few Earth months or years, depending on the exact orbital period and plane of the moon, you'd lose the sun's lumination completely and the world would experience a severe winter-like season. Native plant and animal life would have to evolve to survive these deep freeze cycles even if the moon were slightly warmer than Earth the rest of the time encouraging more tropic or desert-like life. Mechanisms like the weta's ability to be frozen solid and then revive when thawed might be widespread among native life forms. A natural antifreeze component in biological fluids of life forms on this planet, such as a naturally occurring alcohol, might be another coping strategy. [Answer] The easiest way I can think to make a moon Earth like is to just drop a planet into the orbit of the gas giant. Drop a planet? I hear you scoff; I know we're not gods, but we can be mathematicians and astrophysicists. There's really two ways we can do this; we can move a planet from the local system into the orbit of the gas giant, or we can just allow a [rogue planet](https://en.wikipedia.org/wiki/Rogue_planet) to happen upon the solar system and get captured in the gas giants gravity well. Moving a planet takes a little more effort, the 'best' way I can see to do this is our system passes close to another star with enough gravitational force to change the normal orbit of the earth like planet. We can say for arguments sake that the gas giant was on the other side of the solar system for this and hence experienced a reduced effect. [Answer] How do I keep the moon from becoming ice locked like Europa or Triton? I need it to be catch and keep enough heat to be habitable. Jupiter's (or another gas giant like it) is sufficiently large enough, for it's gravitational forces to cause pull and friction on the planet, thus heating it up. This is true for one of Jupiter's moons already, allowing for liquid water to flow. How do I protect the moon from both Solar radiation and the Radiation of the gas giant? You will need to terraform a new magnetosphere, which is what planet earth has to protect against radiation. How do I keep the orbit stable enough to avoid catastrophic failure? You're planet should live either in the "Goldie Locks" zone of it's parent star, or sufficiently close enough to the gas giant, that it stay in it's orbit permanently (which gives it the gravity pull it needs anyway) How would the tides be affected by the gas giant(Assuming that they would be in the first place)? The tides would behave as they do here on Earth, although, the tide might be much higher or lower. How do I keep the temperature semi-regular to allow life to evolve? By maintaining it's orbit to either the parent star or the gas giant. That is where the warmth comes from. ]
[Question] [ Assuming a technological progression roughly similar to that of Europe in our world, what is the earliest that a civilization could have developed rigid-frame [Guns](https://en.wikipedia.org/wiki/History_of_the_firearm)? As far as I know the Chinese even had fireworks in [200 BC](http://www.pyrouniverse.com/history.htm). Some even argue that the [Romans](http://www.alternatehistory.com/discussion/showthread.php?t=135318) could have invented guns as well. Given the technologies and and resources involved with creating and maintaining firearms, how early could a civilization realistically have developed them? [Answer] Your question is a bit contradictory. First you assume > > a technological progression roughly similar to that of Europe in our world > > > and then you ask > > how early could a civilization realistically have developed them? > > > If introducing guns doesn't change the technological progression, what will? Your questions should be this: 1. What is the earliest time a civilization could have discovered black powder? 2. What is the earliest time a civilization could have realized that black powder can be used to guns and not just fireworks? 3. Assuming black powder is available, what is the earliest time a civlization could have produced a matchlock musket or cannon which is reliable enough for military use and cheap enough to be deployed in significant numbers? Regarding the first question, that's probably very early. It just took some chemist to mix stuff and burn it, and to realize that it would go bang. Regarding the second question, that would certainly have been possible for the Greeks. The third question is different because it uses "reliable enough" and "cheap enough". Are you thinking about a single proof-of-concept design or enough muskets to equip an army? * [Siege guns](https://en.wikipedia.org/wiki/Gunpowder_Empires) might become significant even if just a few dozens are available. They would force a redesign of fortifications. * Would it be acceptable if each weapon requires individually produced ammo, or do you insist that it should be interchangeable? * How often are they allowed to explode before they are no longer feasible? A siege gun with a 1:100 change of bursting might be viable, a musket won't be. [Answer] I can't think of any reason that the Babylonians couldn't have made gunpowder, had a time-traveller given them the recipe. However, there isn't any obvious reason for mixing sulphur, charcoal and saltpeter and then setting the mixture on fire. We don't know why someone in China did just that. Was gunpowder an incredibly unlikely invention, or did history get delayed several milennia by our unaccountable failure to invent it sooner? Canons as we know them require a certain level of metallurgical expertise. We know from history that early canons were extremely dangerous to the people firing them. and to anyone neaby. Barrels often burst. Here's a question. Can you make a crude canon with a wooden barrel instead of a cast-metal one? Obviously, not wood alone. It would split along the grain when fired. But what if you wrapped it tightly with hemp rope, or shrank iron bands onto it as coopers do with barrels, or laminated thin strips of boiled wood around a cylindrical form? (There are ancient composite bows; the idea of plywood is not recent). Then most of the charge should propel the ball, at least the first time it was fired. How many shots could such a barrel survive? How great a charge? It's crying out for a bit of alt-historical research. If I'm guessing right, there's a place in the multiverse where Babylon had canons. [Answer] Cannons predate hand-held guns and they were probably invented by the Chinese during 12th century AD. It is hard to tell exactly when gunpowder combination would be discovered by a nation. For example, all the nations have had saltpeter and sulphur ores but only the Chinese came up with the ingenious combination of gunpowder. I assume if chemistry is pursued diligently, a nation would hit something close to gunpowder at most around 1500 AD. Once you have gunpowder and know its explosive potential, canon would be invented real soon. Within nearly 50 years of gunpowder discovery (if it is publicised) I presume. After cannons, it is only a matter of miniaturization till you end up with hand held guns. I think another 50 years would be a safe estimate. ]
[Question] [ Our main character Felixa (female, weight about 70kg) is onboard the [ISS](https://en.wikipedia.org/wiki/International_Space_Station) (altitude 408 km / 254 miles), when something similar to [Gravity](https://en.wikipedia.org/wiki/Gravity_(film)) happens, and the space station is destroyed. Her assets: 1. A parachute similar to the one [Felix Baumgartner](https://en.wikipedia.org/wiki/Felix_Baumgartner) used. 2. 5 kg CO$\_2$ fire extinguisher (brought for experimental reasons) 3. About 10 space suits with compressed air tanks, with about 12 pounds of liquid air each. The suits have built-in EVA controls for a total of 25 m/s Is it possible for our main character to propel her body within Earth's gravity with sufficient air to survive all the way to the ground without any harm? Assume she has sufficient training in parachutes and orbital science. [Answer] Short story: Nope. The biggest problem here is being able to change your velocity enough to cause you to de-orbit before you suffocate. If we say (for the sake of argument) that below 100km you experience enough drag to slow you down and get you home, they you still have to change your periapsis (point of closest approach) by 300km. To do this you'll have to change your velocity by something in the order of hundreds of meters per second. Your average fire extinguisher might change your velocity by [10m/s](https://www.quora.com/Can-fire-extinguishers-be-used-as-thrusters-in-space-as-shown-in-movie-Gravity) in a vacuum (call it 15 for good luck), and if you put all the other suits together and kick off you might get another few if you can jump really high while wearing the restrictive spacesuit. EDIT: As Molot's comment points out, by paragraph above is probably wrong, however: you still need to make sure you have enough oxygen to survive until you hit the atmosphere, and even after that you still suffer my paragraph below. The time needed is going to be roughly 45 minutes with 110 m/s. I'm not sure how long the oxygen tanks will last, but it's worth assuming they'll last long enough. Of course: all of the delta-V considerations are sorta thrown out when you consider that even if you manage to get yourself to the edge of the atmosphere you'll be hitting it at somewhere over 7km/s. For reference: Felix was moving at approximately 0km/s, as he wasn't in orbit but jumping from a balloon. Your average spacesuit [does not have the right shape](https://www.quora.com/Is-it-not-possible-to-upgrade-space-suits-so-that-they-can-survive-re-entry-and-then-chute-down-like-Felix-Baumgartner/answer/Robert-Frost-1) to survive that. He also only jumped from 39 km up, much lower than the edge of space, and so didn't have to worry about angle of re-entry or any of that stuff. So: My recommendation is this: Use the extinguisher to control your attitude, point yourself at the sun, and enjoy as many sunrises as you can before suffocating. [Answer] Maybe enough to deorbit but not nearly enough to avoid reentry heating. The ISS orbits at 7.66km/s or 4.76 miles per second. A CO2 cannister yields tens of meters per second $\Delta$v. So, Felixa will be able to deorbit herself but not enough to avoid the heat of reentry. Remember, orbit isn't so much high as fast. Hitting the atmosphere at 7km/s is going to hurt. The ISS is [already deorbiting](https://en.wikipedia.org/wiki/ISS_Propulsion_Module) so Felixa will too. > > The ISS requires an average 7,000 kg of propellant each year for altitude maintenance, debris avoidance and attitude control. (emphasis mine) > > > Whether Felixa will run out of oxygen or not in the reentry period is immaterial. She doesn't have the $\Delta$v to "drop out of the sky" like Mr. Baumgartner did and will thus burn up on reentry. [Answer] Let's do some (rough!) sums and apply conservative assumptions. Felixa has a gravitation potential energy of 70\9.8\400000 = 274400000 J But that assumes constant gravitation. Though gravity is not that much weaker at 400 km up. Let's say that GPE is about 200 MJ. Kinetic energy is more interesting. Assuming a velocity of 7.66 km/s she has 0.5\70\7660^2 = 4107292000 J So about 2 billion Joules of kinetic energy. Okay, now how long does she have to get rid of it on the descent? In a parachute the terminal velocity is about 8 m/s. Assuming that she maintains this rate of descent from the top of the stratosphere (which is extremely favorable values, given that the atmosphere is 1/1000th the pressure as at sea level), then Felixa lands in about 6000 seconds. So to shed all that energy, she needs to be doing about 350 kW. With more realistic assumptions, probably orders of magnitude more. Even more realistically, her chute will be torn to shreds and she'll hit the ground with a boom. Yeah, she's toast. And no, nothing she can do can save her. None of what she has can match up to the numbers at play here. ]
[Question] [ ## Context A God contest is organized. Each participants starts with a human-free alternate Earth and a certain amount of god-credits to buy humans and supplies. Some Gods used a big part of their budget to acquire Legendary Artifacts such as a [duplication machine](https://worldbuilding.stackexchange.com/questions/25072/duplicating-people-to-expand-a-civilization) or a [magical sperm bank](https://worldbuilding.stackexchange.com/questions/22415/planetary-colonization-by-a-female-crew), and others preferred to do go with the number and buy a lot of humans. Judges evaluate the participants every hundred years and give to each god grades based on a lot of (sometimes contradictory) criteria. Examples of criteria : increase of population, surface colonized, technological advances, originality of Arts techniques, efficiency of governments, weirdness of religions, complexity of languages, diversity of cultures, number of bananas eaten per day, etc. Most contestants specialize in a few specific domains. ## Our Contestant One god chose the "strength in number" approach and bought a huge bulk of randomly generated humans, with hunter-gatherer tech level, basic notions of agriculture and a few tools. His goal is to create the most diverse possible cultures/civilizations in one thousand years. He is looking for a set of locations where hunter-gatherers would survive and multiply, and that are different and distant from each other. He already selected a few areas to drop off his humans : * [Manaus, Brasil](https://www.google.com/maps/place/Manaus,+State+of+Amazonas,+Brazil/@-2.0745875,-60.9853718,4.96z/data=!4m2!3m1!1s0x926c0567d6e5a85b:0xf0db730c4985e2dc) : in the hearth of Amazonia, starting point for a Rain Forest civilization. * [Thunder Bay, Canada](https://www.google.com/maps/place/Thunder+Bay,+ON,+Canada/@46.9436559,-87.2226629,6.5z/data=!4m2!3m1!1s0x4d5921774c16e98d:0x3d0557348f1d8b74) : Great Lake area, the northernmost location of this list. * [Haridwar, India](https://www.google.com/maps/place/Haridwar,+Uttarakhand,+India/@29.8435016,78.2021645,6z/data=!4m2!3m1!1s0x3909470eb8ee57c9:0x4e449176a640f5f3) : close to the source of the Ganges, where it's still close to the Indus, the settlers will then follow the river stream to colonize the rest of the subcontinent. * [Palermo, Sicilia](https://www.google.com/maps/place/Palermo,+Italy/@38.4273751,14.0186998,6z/data=!4m2!3m1!1s0x1319e8c9814ed099:0xa0b042c233bd880) : fertile island in the middle of the Mediterranean sea. * [Vanderbijlpark, South Africa](https://www.google.com/maps/place/Vanderbijlpark,+South+Africa/@-25.967614,27.3761789,6.92z/data=!4m2!3m1!1s0x1e944554b296eba5:0x8eefa9dbd9122ebd) : has a river, copper and iron ore in the general area (I wanted a settlement with access to both, but I'm not sure this is the best choice) * [Pape'ete, Tahiti](https://www.google.com/maps/place/Pape'ete,+French+Polynesia/@-17.2341441,-151.6488321,5z/data=!4m2!3m1!1s0x769a3a1c874f6695:0x62d6db532881362b) : good starting point for an Polynesian culture. * [Launceston, Tasmania](https://www.google.com/maps/place/Launceston+TAS+7250,+Australia/@-41.5311103,147.0927052,8.75z/data=!4m2!3m1!1s0xaa70a6e12e84fd5d:0x503c94dd0de1990) : safe starting place before colonizing Australia, has fresh water. (ugly) Map of the settlements : [![World distribution of settlers ](https://i.stack.imgur.com/mwonD.jpg)](https://i.stack.imgur.com/mwonD.jpg) --- ## My Question I'm trying to extend this list but every good location I find seems too similar to a location I already selected. At this point I need only one new settlement area. What is the best location to complete the list ? It should allow hunter-gatherers to thrive, be reasonably close to other colonizable lands, and be situated in a biome not yet present in the list. The objective here is to diversify the cultures, which are strongly influenced by their environment, so I'm looking for a place with unique flora, fauna, natural resources, climate or geologic features. Note : If you propose a list of places sharing the exact same features, I'll accept it as one answer. [Answer] How about a Steppe environment? The [Tibetan Plateau](https://en.wikipedia.org/wiki/Tibetan_Plateau#Animal_and_plant_life) would be a good starting point if you wanted a nomadic society, though I'm unsure as to how many people it could reasonably support if they were just dumped there (the same is true of all the regions you've selected though) The range of weather and temperature conditions throughout the year would breed a race of hardy yet adaptable people, and while the geological region gives a few options for expansion (see: all of Asia) it's also remote and inhospitable enough that their culture would be able to develop apart from the rest of the world for a while. If history repeats itself, then you could end up with a horde of [men on horses](https://en.wikipedia.org/wiki/Mongol_invasions_and_conquests) causing trouble for a while. While the flora and fauna might be quite similar to Thunder Bay, the harsh conditions and sheer altitude should breed a completely different race of people. Oh, and [Yaks](https://en.wikipedia.org/wiki/Yak). Lots of Yaks. [Answer] OK, lets start with the basic rule that all initial civilizations should begin around freshwater sources (rivers or lakes that is). In a world teeming with wildlife, hunting should not be such a big problem. Finding drinking quality water is the biggest problem your hunter-gatherer pioneers are going to face. I have attached a map of where to place the 8 initial pioneers. Here is some detail. The points are numbered from right to left. 1- Darling River, Australia. Plains terrain. Unique fauna and flora of Australia. Excellent for initial kangaroo and moa hunting and later shift to agriculture. 2- Okinawa, Japan This island gets Kokuba, Nakama and Nakara rivers. A series of islands will ensure that this would quickly turn into a fishing civilization once the pioneers have hunted the island's edible fauna to extinction. A unique seafaring civilization, I must say. 3- Borneo, Indonesia Once again, an island civilization. But unlike the Okinawan pioneers, Borneo pioneers have a much better go at agriculture and the large Borneo Island can sustain hunter gatherer culture for longer. Furthermore, the region has a distinct (warm and wet) climate than the Okinawan region which results in tropical rainforests and an array of breathtaking beaches. Freshwater source is Kapuas River. 4- Indus River, Indian subcontinent I prefer this over Ganges as the Indus Delta has more terrain variation than the Ganges Delta. Here you get forest, semi desert and completely desert environments at far lesser travel than you would, in the Ganges Delta. Furthermore, it is closer to the Himalayas series of mountains so that adds yet more diversity. No wonder Indus Valley civilizations predate Egyptian or Ganges. 5- Nile River, Egypt/Sudan This would be the best place to place your African civilization. The Nile has vast areas of forest and desert terrains and game is plentiful. Excellent place to begin spreading in the African continent. 6- Danube River, Bulgaria Great place for the Polynesian culture and spreading into Europe. 7- Amazon River, Brazil This is the textbook-perfect place to begin the rainforest civilization. People in this region will probably never give up hunting permanently, considering the vast amount of game they find here. 8- Missouri River, America The best place to begin the great plains civilization. Like the Indus Valley, this is a heaven upon Earth for the early settlers. [![enter image description here](https://i.stack.imgur.com/W1xSG.png)](https://i.stack.imgur.com/W1xSG.png) [Answer] As soon as you want your society become farmers, i recommend you any place with very fertile soil. Chernozem is one of the high ferile soil,a nd quoting wikipedia: > > There are two "Chernozem belts" in the world: from eastern Croatia > (Slavonia), along the Danube (northern Serbia, northern Bulgaria > (Danubian Plain), southern Romania (Wallachian Plain) and Moldova) to > northeast Ukraine across the Black Earth Region and southern Russia > into Siberia, and the other in the Canadian Prairies in Manitoba. > Similar soil types occur in Texas and Hungary. Chernozem layer > thickness may vary widely, from several inches up to 60 inches (1.5 > metres) in Ukraine. > > > Which and places marked as red on map, might be best for that kind of society. [![enter image description here](https://i.stack.imgur.com/zuq2u.jpg)](https://i.stack.imgur.com/zuq2u.jpg) EDIT If it is full reboot, and we have similar circumstances when our civilization was created, i think it is worth to mention about places where sivilisation emerged in our world. * Fertile Crescent : Egiptians and Sumerians * Indus river : Harappans * Yellow River : Ancient China (Xia Dynasty) * Central Andes : Norte Chico * Mesoamerica : Olmecs [Answer] The Andes in Peru and Bolivia. The climate is more diversified and generally more clement than in Tibet. It's close to the equator, therefore the region experience only small variations in temperatures over the year. And it has good rainfalls except on the western slopes. It's in the mountains. That means a wide range of different climates, crops and cultures. This diversity might favor commerce as each pockets of settlements will have different crops, the incentive to trade is greater. ]
[Question] [ I'm running a Pathfinder (think Dungeons and Dragons) campaign, and I'm creating a country which has a centralized government that is responsible for many major cities, ports, etc throughout the country. The world itself is your typical fantasy setting with medieval-esque technology and creatures. Typically in these settings, you don't see a centralized government running a country, but instead, each city is a kingdom of its own, ruled by a king. I want to make the government play an important role in the daily lives of its people such that the quality of living in this country is much greater than living in other, non-centralized parts of the world. However, the only service I can think of offering on a country-wide level is a form of "public transportation" -- caravans accompanied by country guards that travel from city to city in order to offer safe journeys to merchants and travelers within the country. What other services could be offered by a centralized government in this setting that would significantly increase the quality of living for its citizens? [Answer] Law enforcement Specifically, the state would protect the commoners from abuse by the nobility. This would allow more wealth at the bottom which would allow a more diverse and inclusive economy, which would help create a healthy middle class or artisans and merchants. State would also keep kings roads safe from brigands and "tolls" by local strongmen, allowing more trade. Better law enforcement would reduce level of corruption allowing businesses to succeed on their merits which in the long run improves economic efficiency. Food management Local famines used to be relatively common. A strong state could secure the food supply to protect population from such. This would improve agricultural productivity. It would also allow the agriculture be more diverse, which would increase trade. Stability Increased stability promotes investing in the projects that need a longer time to be productive. This would typically include infrastructure such as harbors, roads, mines, dams, irrigation systems and so on. Building more of those obviously improves future productivity. Increased stability also reduces the risks of lending money, which lowers interest rates, and makes all investments cheaper to make. Regulation Within reason people who do not die in building collapses, fires, or epidemics from tainted water sources or food are more productive than people who do. Even after you account for the cost of regulation. Same goes for many workplace regulations. Employees without rights are cheap and you can make them work hard, but only make the owner rich. Employees with rights make the entire community wealthier and more productive. Just some examples. Should get you started in thinking up examples that work for your campaign. [Answer] Water Aqueducts and other engineering projects to bring clean water into the cities. For the money, that will bring the biggest bang for the gold piece in terms of public health and welfare. Sewer Similar projects to get waste out of the city, to help prevent outbreaks of disease. [Answer] Infrastructures: if we consider the construction and the maintenance of large infrastructures as a service, yes this is a great way to improve the life of the people. The canals help the economy by linking different regions and can also be used for irrigation. Road also facilitate transportation. Building and maintaining a transportation system is something hard to do with a decentralized government. Education and art: Under peace, a centralized government can invest in education and the arts. They build institutions accessible mostly for the nobility. The number of places are limited because the state probably can't afford to educate everyone. Who can enter? is all up to you, you don't have to limit it to the nobility. Most centralized governments also promote the arts. This can be seen as a service like it is today. Some civilizations considered a proficient artist to be as equally important as an educated person. They could open arts academy or simply finance the artists at the courts or create national contest to promote creativity. Security: Building and maintaining defensive structures to prevent invasions. While decentralized states can also do that, it lacks coherence. It must be considered as a system taking in consideration the fortresses and the armed forces. Social security: This might seems uprising but to some extend, it's possible to have some measures even in medieval times. The Tang dynasty used to provide aid to the homeless in the capital. This could also be extended to help other people like the poorest or the very old. Old persons were very vulnerable : with no pension systems most had to work til their death even if their health was bad. Your state could provide help to these needy people without ruining himself. If you have a professional army, you could consider helping the families of fallen soldiers. Not only it helps the people affected but it also help to improve the prestige of the army as an institution. With better conditions, your likely to attract the good talents. [Answer] Coins: Many role playing games use generic "gold pieces", but different kingdoms would have different coins and accept foreign currency from traders only at a discount. The central government will be different. Also, they'll go after counterfeiters. Measures: All towns will have the same bushel, foot, or pound. Again a boon for traders. Possibly a Postal Service: Messengers or coaches going from town to town on a regular schedule, supervised by the government to make sure they're mostly honest. ]
[Question] [ The movie [Planet of the Apes](http://en.wikipedia.org/wiki/Planet_of_the_Apes_(1968_film)) shows (and in the end explains away) humans talking with the apes in English. Assume we don't want that plot point but the setting is similar otherwise: * The human is a sole survivor from a space mission and has limited tools. After crash-landing he's living off the land (no computers etc). * The apes are (on this world) a superior species to humans. Humans are zoo exhibits, not peers. Assume that a captured human will be treated about the same way we treat chimps in zoos on Earth. * The apes are on the technological level of Earth 1970s, but with no space program. * The apes speak a language which is hard to learn and hard to understand, but within your cognitive possibility to learn it (imagine Finnish language for an English speaker, as an example what I mean). They will assume that humans can learn up to the level of "Polly wants a cracker" but that humans can't really learn and communicate. In this setting, how could a lone human communicate with the apes? [Answer] There are a lot of factors that can affect a timeline here. Questions pertaining to the lone Human: * Does the lone human only know one language? Were they in a multilingual environment from birth? * How strong is their knowledge on grammar? Grammar is a bit universal...knowing additional languages would help a person understand the various ins and outs of grammar. My experiences in Belgium taught me English - beer Dutch - Pint. English - small beer Dutch - Pintje. the -je ending in this case makes it diminutive...knowing these concepts will help one recognize it in another language * How old are they? Humans at a younger age (under 6) have an inherent ability to learn language simply by being immersed in it. Odds are our Astronaut here is older, but some humans retain this ability better than others. Ever read the book 'Shogun' where an English sailor lands in Japan and through sheer exposure learns Japanese in a shorter period of time? And a couple pertaining to the apes language * Does it contain mostly the same sounds we use, or are their a variety of sounds that they can make that we would struggle with. Are there sounds that we could make, just don't (eg: French contains Œ sound that english people can make if they work on it, but don't do it naturally) * Is there a tonal nature to the language (tone inflection is pretty meaningless in English, perhaps an upwards inflection at the end of a sentence would denote a question...in Mandarin, 4 words that would look identical to an english speaker could have 4 meanings of mother/hemp/horse/scold depending on the tone used). Thai languages have 6 tones making it that morr complex. * Are there other sounds/variations that we are simply incapable of differentiating in their language? * Does the language contain genders? or another attribute on a word (strong vs weak?) * How thorough is the use of tense (Sasak, an Indonesian language, completely lacks tense...everything is in the present tense. This makes the language considerably easier learn than English where would have being had appears to be a valid tense use). As social beings, humans are actually quite adept in picking up communication. Actual learning time will vary pending all the factors above, but the odds are this astronaut would probably surprise these Apes with how readily the Human starts to pick up on their language and it's grammatical components. Not very likely the human will fully catch on to the language and they'll speak it more in a broken form, but it would be a relatively short time (1 month) before the human starts speaking it in very broken forms (like stringing nouns together to kinda form sentences). Beyond that...it's really hard to give any timelines without having the answers to above questions Alternatively, there are some more common methods of communication, such as math, that the human could employ to denote he is far more intelligent than what he is being treated as. I would assume the astronaut knows calculus to some degree...poking a hole in his water dish, displaying the waterflow out of his bowl in algebraic terms, finding the derivative of that and graphing it over time on the floor...any sign that the human is far more intelligent than he appears may entice the Apes to work on communicating with him more thoroughly. [Answer] Try drawing pythagoras triangle in the sand. It will show far higher understanding/knowledge than average caveman. In original movie, guy made paper plane from a sheet. I seen [original movie](http://en.wikipedia.org/wiki/Planet_of_the_Apes_%281968_film%29) but not the new one. If language is hard to learn, try drawing pictures showing your deeper understanding of nature. Try build simple tools or mechanisms like [block](http://en.wikipedia.org/wiki/Block_%28sailing%29). If ape's language is [click language](http://en.wikipedia.org/wiki/Xhosa_language) you may not be able to become fluent speaker for a long time. Google for some examples. [Answer] Don't act like a beast. Learn their language, you obviously have nothing but time. Befriend your zoo-keeper. If you have materials, learn to weave, or make yourself other useful tools to improve your environment. [Answer] Talking does not need to use speech to happen. Written languages are also fantastic for communication. Hint: we are communicating over one right now. But the written word is a very high-level form of communication. You should be able to recognise that Mandarin (Chinese) is a viable method of communication between two people, but that doesn't necessarily mean you can use it (yet). What I suggest is that you find a common language between yourself and the Apes. As others have already hinted at; mathematics is a pretty fine common language. It's also fairly high-level, which makes it difficult to communicate things like "Hey, I feel hungry. Could you do me a favour and let me out of this cage so I can fetch something to eat?" So let's rewind a bit, and choose something else. Initially, you want something a little more practical. People and animals leak lots of information in the form of body-language. Gesturing is a more forced form body-language, and is pretty intuitive. What this leads onto is sign language (ironically, sign language is present in the reboot Planet Of The Apes). There's no universal sign language. Most countries follow one/few standards, just like most countries have one/few accepted written languages. My knowledge of signing is very limited, but I've been told that the sign for eating is common among several of them. Learning to sign would allow you to talk to Apes. As signing is primarily for the deaf and mute, it has the advantage of you not needing to know how to speak their language in the first place. More accurately, many of the methods employed while teaching sign don't make the assumption that the learner can already speak Ape. Final note: If their technological level is equivalent to the 1970's then it would be safe to assume they have computers (albeit, clunky slow ones). Programming languages share lots of commonalities with maths, but allow you to phrase statements that are much more useful to communicating between two intelligent animals. Computer code also follows very strict structure. This is a boon, because structure means predictability. Patterns will emerge in the code, while you may not understand any of the letters, given enough exposure, you will correlate collections of symbols with meanings. A 1970's computer programming Ape might be the easiest thing to talk to... so long as you have a computer. [Answer] I would demonstrate intelligence so they become interested and start teaching you their language. Demonstrating intelligence is easy enough: use math, and start teaching them English. Counting and arithmetic are common foundations for language. Start with groups of similar things (3 apples), then move on to simple glyphs (3 scratches in the dirt) then numbers (the number 3). Cut an apple in half and write 1/2. An observant ape should figure out what's going on. Encourage them to write their own numbers next to yours. Once you can communicate numbers you can communicate some basic words for logic. "ONE apple AND ONE apple IS TWO apples." It doesn't matter if they give you the word for "plus" vs "and" or "equals" vs "is", it's a start. You can demonstrate higher intelligence with math. Start with some fundamental sequences. * 1 1 2 3 5 8 13 21 34 55 * 2 3 5 7 11 13 17 19 23 Geometry is another common language. Draw regular geometric shapes. Draw platonic solids. Draw circles with tangents. Bisect a square into triangles. Do any number of purely geometric proofs. You can use the shapes to build up some words. Triangle: "3 sides". Square: "4 sides". Hexagon: "6 sides". Another approach is to demonstrate and play games which are simple to teach, but have some complex outcomes. Start with tic-tac-toe. Simply play with yourself to demonstrate the rules. Maybe move on to [dots and boxes](https://en.wikipedia.org/wiki/Dots_and_Boxes). Then Checkers. Then Go. Another is to point at things and name them. Do it with everything. Do it consistently. Write the English name on everything you can. Similarly, perform actions and say the verb. The simple act of being able to consistently label things demonstrates more than animal intelligence. Any of these behaviors from an animal should merit some reaction and interest. Someone is going to get it and start teaching you ape language... assuming there isn't a religious conspiracy to suppress knowledge of human intelligence. [Answer] One point that hasn't yet been covered by the other answers is that it is quite possible to show someone that you have complex speech capabilities without actually sharing a language. I don't speak Chinese, but when I hear Chinese spoken, I can tell that there is meaning and structure there compared to when a dog barks or an ape using various grunting noises to communicate. Similarly, we can tell that there is some meaning and syntax among the "languages" of other intelligent animals like dolphins, and we have put quite a lot of work into establishing communication with these species even though we don't expect them to ever learn English. The advanced ape species may not realize that your speech is as advanced as theirs, but I suspect that just by speaking to them in your native language you could convince them that you are intelligent. If you coupled that with writing things in the dirt or on the wall, you may really pique their interest. That would get you past the issue of them thinking you are just imitating their speech like a parrot. If you could catch the interest of one of their zoologists, then you could work more closely with them to teach each other your languages, which would greatly increase the speed at which you learned. [Answer] As I remember about the different "Planet of the Apes" from the seventies, their world is an alternative future derived from 20th century Earth. The Apes civilization is located in North America, near today New York, as you could conclude from the ruins of the Statue of Liberty. The events that triggered the Planet of the Apes happened in the 20th and 21th centuries: * the extinction of dogs, cats and other similar mammals from a viral disease * the extensive use of apes as pets and slaves, even with selective reproduction and genetic tampering for desired traits, like better understanding of human gestures and speech * the arrival of talking apes from the future in a human made spacecraft and the birth of their son who learns English from a circus director (played by Ricardo Montalban) and becomes the leader of the apes' revolution. Then, one can infer that the language the future apes use will be a derivative from one or more of the main languages used today in North America: * English * Spanish * French And, as a Roman from 2000 years ago could easily learn today Spanish, French or even English, so an astronaut like the one played by Charlton Heston, a person selected because of his skills and intelligence, maybe even initially bilingual or trilingual, could easily learn that future language. Also the apes language is a multispecies language (talked by chimpanzees, orangutans, gorillas and even bonobos) and remembering that humans are also apes and genetically more closer to chimpanzees than the latter are to gorillas or orangutans, it is an easy conclusion that languages will not be more difficult to learn to a modern human than to anyone of the other possible future apes. The future apes also have books, many of them copied from human books, and as classical Latin influenced modern European languages, "classical" English, French and Spanish could have influenced future "Apish". [Answer] In today's Earth there are 5 great apes species (homininae): * orangutans * gorillas * humans * chimpanzees * bonobos Humans are not less apish than any of the other four. Since the generic Planet of the Apes also has the same five species and four of them speak the oral language, I do not see any difficulty for a selected human, an astronaut, a person with high IQ and sophisticated culture (in the anthropological sense), already speaking at least a different and complex apish language (English), to learn a new language, as any committed adult human with his background will do it. ]
[Question] [ As I understand it, the principle of relativity was accepted from Galileo until Maxwell, whereupon the equations which predict constant speed of light imply a preferred reference frame in a Euclidian space, suddenly making relativity testable. The Michelson–Morley experiment showed that light speed was constant in all reference frames, ergo Maxwell, relativity, or Euclidian space had to be wrong. As it turns out Euclidian space is what broke, and moving the equations of physics to Minkowski space allowed us to preserve constant light speed and the principle of relativity (although relativity implies some surprising things in Minkowski space, nevertheless it's merely a logical consequence of the geometry). Suppose we changed something else instead? Would physics still make sense if the Michaelson-Morley experiment had shown that light speed was not constant in all reference frames? * i.e. would everything else still be logically consistent, perhaps with some tweaks, and hence the universe would have a sense of absolute space and time? What would be the consequences of this? I guess another model universe could have no preferred reference frame but that would imply non-constant lightspeed. Is this a logically consistent hypothetical physics? * I imagine that would imply a change in the assumptions underlying Maxwell's equations, but my physics isn't good enough to follow this line of reasoning through. What would we have to adjust to make this work, or is it nonsense? [Answer] From what I have been lead to believe, there was a non relativistic universe model which we used after Maxwell. It had a large number of "correction" terms which resulted in varying speeds of light. The proving power of Minkowski space was not that it was "more correct," but that it baked all of those correction terms into the space. It was found that this was a more convenient way of thinking about the problem, so we ran with it. Our universe is not defined to be a Minkowski space, but rather we have found the laws to be simplest if we map our models into a Minkowski space. This is the same argument for saying "the Earth was never flat, but we found the laws of navigation to be simplest if we map our models onto a flat surface." As for a world where there actually is a "preferred" frame of reference for light, it would likely have little impact on the world. Given that we could not measure the speed of light until Maxwell's era, and the fact that the universe doesn't even seem to be very dependent on this speed, I would not expect much to change. As technology advances however, this ether like behavior might have a large effect. As we become more and more enamored with things that move at the speed of light, being able to measure things with precise timing would be an issue. Atomic clocks would have to synchronize to account for their rotation within the ether. There would be a preference for building structures in the ether frame whenever possible, making calculations easier. Eventually there could be a galactic building crunch, as everyone tries to align themselves with the ether. [Answer] By "non-relativistic" I assume you mean Galilean relativity. That is, a universe with no weird high-speed effects, where changing reference frames is as simple as adding velocities and there is only one universal time. The reason Galilean relativity was the prevailing theory at one time was that it is an extremely close approximation to reality at the low speeds we deal with. In order to make it exactly true, then all speeds must be small compared to the speed of light. In other words, the speed of light is infinite. Just take all our physical laws, and take the limit as $c$ goes to infinity. Then the factor $\beta=v/c$ is always zero, and the factor $\gamma=1/\sqrt{1-\beta^2}$ is always 1. This means there is no time dilation or length contraction. This universe is logically consistent, but due to the infinite speed of light there would be no electromagnetic radiation as we know it. I'm not sure what implications this has, but you can probably handwave those problems away. ## Details (Update) Maxwell's equations implicitly involve the speed of light (they must, since they are what govern electromagnetic radiation i.e. light). The key one to consider is Ampere's law: $$ \nabla\times\mathbf{B}=\mu\_0\epsilon\_0\frac{\partial\mathbf{E}}{\partial t} $$ It so happens that the product of the constants in that equation is related to the speed of light: $$ \nabla\times\mathbf{B}=\frac{1}{c^2}\frac{\partial\mathbf{E}}{\partial t} $$ This means that if $c$ is infinite, this equation becomes: $$ \nabla\times\mathbf{B}=0 $$ That is to say, instead of electrodynamics we have [magnetostatics](http://en.wikipedia.org/wiki/Magnetostatics), under which conditions no waves exist. Another way to think of this is with the relationship between frequency and wavelength: $$ \lambda f=c $$ If $c$ is infinite, this equation can only be satisfied is if the frequency or wavelength (or both) are infinite. Since infinite frequency makes no physical sense, we must conclude that all waves are infinitely long: that is, that there are no waves at all. ]
[Question] [ For some time, I have been playing around with the idea of a medieval-like world, but with the twist: Some sci-fi tools exist and are fully operational. But I cannot come up with good and plausible way how this would be possible. To make it into points: * The whole society is pure medieval, before firearms were developed * But, some people have access to, say, blasters and light sabers (not necessarily both, not necessarily any of it, but basically something completely off the level of that technology level) * The in-universe explanation would be either "magic" or "gift from Gods", but generally, the people got them, because they found it and guessed the usage by trial and error. Now I need a plausible, non-magic explanation to make the above possible. And, honestly, I am willing to abandon the whole idea if there is not an explanation at all. BTW, while typing the question, I might guess your questions, so I have a few more things: * The high tech weapons (or tools) should be mediocre hard to find. If you need it for your explanation, you may bind them to specific place. * There may be more than tools. But if you are guessing books or manuals, they can exist and be found, but must be not understandable to current generation (imagine finding nowadays something which comes with a book written in Egypt hieroglyphs) * Symbolic pictures, or comic books (low level try to communicate something [50 000 years in the future](https://worldbuilding.stackexchange.com/questions/3429/how-might-modern-humans-leave-a-message-for-50-000-years)) may be found, but will come either hugely misinterpreted or not understood at all * And yes, one idea I have is, that the set up is actually far away in the future and something happened. But I am trying to imagine what exactly happened and how in the world did it leave so many tech behinf [Answer] Well there could have been some kind of space battle over the planet at some time in the past. Maybe several different ships crashed into it. The Crash might have been as simple as a controlled fall and a hard landing. Few to no survivors. So the weapons are 'alien' in manufacture. else If you want the survivors to populate the planet then you need a way to get a lot of them down there (maybe escape pods from other ships?) and have a reason to leave the crashed ships alone for a few a thousand years or so, maybe radioactivity from the damaged ship(s). Thought I'd add more to the survivors section. If they can't get off the planet, and they can't use the tech in the ships, they will pretty much have to go native and would likely be at a medieval level of tech in a few centuries, though with some strangely high levels of knowledge in odd left over areas. [Answer] This can be handled in many ways, so it all depends on how fantastical you want to go. While you could go with the idea that civilization used to be sci-fi but some cataclysm set people back to a primitive state (society would need to be rendered down to pre-literate levels for a very long time for all knowledge to be lost), this gives you the problem of your sci-fi artifacts still being functional and powered after thousands of years of just sitting around (even in the best of cases several thousand years will not do the basic materials any good, much less the electronics, unless you are really going beyond the laws of physics kind of sci-fi where such advanced technological devices will never degrade). The more plausible alternative source to advanced ancient civilizations is an outside supplier - artifacts are intact and functional because they are relatively new rather than 50k years old. This could be aliens, but that seems like a lazy hand-wave catch-all excuse for random inexplicable weirdness (though popular to some). There could be a hidden advanced civilization. Think about the people alive during the cataclysm - perhaps some of them took refuge in underground vaults but adapted and don't want to leave. They might occasionally venture forth unto the surface to check things out (a survey team or class field-trip), though trying not to interact with the primitive surface dwellers. Occasionally they discard broken or worn out tools (meh, setting 3 stopped working, time to get a new one even though other settings still work), or some are just accidentally lost and their junk discards become magic relics. Perhaps off-world colonies were established before the fall but they have prohibited all contact, but there may be outlaws/smugglers bringing in some illicit cargo (swap a plasma rifle for locally grown narcotics). Or without any interaction at all, you can still have illicit safari hunters from the colonies not being careful about leaving no trace - they came down to hunt (an adventure illegal in the interstellar community), but just tossed a half-discharged power-pack, accidentally dropped a scanner in their excitement of spotting their next kill, or just got scared of the big creature and dropped what they were holding and ran. [Answer] This probably isn't a valid point on the matter, but in the video game "Starbound" there is a race of intelligent robots that all function as if they are living in a medieval society. Their weaponry is modern, and so are their tools and other equipment, but in terms of aesthetic wear and what their buildings look like, they are medieval. The backstory of these characters, if I can remember, is that they were designed as a form of entertainment for humans, in that the humans would go to historical fairs and see these intelligent robots acting out the roles that humans of the time would've been in. After a time of these robots existing and being programmed not to think that they were acting but to be in belief that they are actually living in the medieval times. When the humans that built these robots died out, along with most modern human technology, the robots were left alive to act out the roles they were programmed to posses, and eventually, discovered what modern human technology they could use. Just a thought. [Answer] Have you heard of Mortal Engines the book? Its the first in a series about cities on wheels. Sounds unrelated but the story is set 4000 years in the future. In that time they find technology from our time and talk about it as if it were ancient magic. They don't understand things like CD players or mobile phones. Some people wear these items as talismans, others take them apart to try and understand them. Some of the things they find are super weapons capable of destroying whole cities. You could follow a similar idea: Civilization has regressed but technological relics from the past still exist. People don't understand them and so they believe them to be magic, so much time has passed that these things are very rare and no suitable technology exists that allows people to understand how these relics function. EDIT There are many possible reasons for something like this happening: * Nuclear war (or some major war), this is the method that Mortal Engines and Adventure Time uses * Disease wipes out almost everyone on earth * Global warming reduces population * Meteorite hits the earth and humans regress etc [Answer] Politics and Religion can be handy tools to create situations such as this, probably working hand in hand. It may make sense for a cabal of political and religious leaders to decide that a feudalist dictatorship would be "better" for everyone and that in order to maintain it they must crack down on the availability and level of technology. ]
[Question] [ Scenario: A new civilization is born. People are emerging from their wandering lifestyle to the settled agriculture and trade based survival. We could assume that they'd implement a town centre and start administrative operations. This could be of various sorts such as: * Resource management * Keeping records * Managing population I'm assuming this could only begin by an individual's initiative rather than with a group coming forward with everything planned ahead. If this is the case, how would the leadership evolve in the future? When would it distribute power and make formal laws? Is this a likely scenario compared to the formation of a democracy from the very first? If it is possible for a group to initiate the town's governance, how would it implement its power? [Answer] That's a bit of an oversimplified view of civilization. If I understand your premise properly, you're talking about small tribes or nomads gathering together to found a town. ## Leadership is not dictatorship First of all, they would already have some form of leadership. Even tribes and small groups have de facto leaders, established either by consensus (people just seem to go to them for questions or guidance in daily matters and they have everyone's trust) or by heritage (the chief's offspring become chiefs in their own right and people are fine with it). While this resembles, in the modern political sense, a dictatorship, it is in practice very far from it. Dictatorships have and require a huge distance from the low rungs of society - town leadership is rarely that far removed, unless it is supported by a more powerful authority. In a mere town, what kind of dictatorship could you have? And if your concern is for the longterm implications of that model, there is nothing to indicate what the future political structure will be, either way. Pretty much every early civilization had de facto leaders in the local sense and grew within a strict monarchy. It was only millennia later that some form of official recognition of public will was established within political structures. ## Politics hasn't always worked the same Even this is oversimplification. Under ancient monarchies, the general will of the people was taken under consideration - monarchs and leaders who ignored it where considered unjust and where unliked, no matter their authority, power or the effects of their actions. Again, even after the need to reflect public opinion was established, it was a long long time until we had anything resembling modern democracy. The ancient greek and roman republics where heavily aristocratic and only the rich could really vote - 9/10 of the population had no say in anything. It was just a glorified lobbyistic monarchy. ## Nope Considering the above and how recent the notion of a "dictatorship" really is, I'd say no, it doesn't lead to any kind of dictatorship. It would be a long time before there was authority far removed from most people and it would probably be centuries or millennia until public representation was a clear ingredient in political systems in order to make ignoring it (a dictatorship) an ingredient as well. Overall, it's impossible to tell how a civilization will develop just by observing its early stages - especially when we have so few examples to work with. It could develop in all kinds of ways depending on events, contact with other cultures, social reforms, who knows. ## Scales The formation of democracy straight up is nearly impossible - there is a simple reason: the problem it solves has not been detected or defined yet. Until then, you have implicit and de facto leaders - that structure happens in small groups due to efficiency and division of labor; until it is proven to be ineffective (which in our civilization happened only a few centuries ago), it will be maintained to the bitter end. Also, your impression that a city can only be started by the initiative of one person, is in conflict with how communities and cities form in general. People aggregate to cooperate better - when there's more people, there's more hands to work and less work for everyone, because work and its yield don't scale linearly. That's why you get tribes in the first place. Often, cities spring up where resources are, because everyone goes there - they also emerge around mines, fields, factories etc. . It has to do with proximity and the efficiency of communities, not initiative. From an individual's point of view, cities just happen. [Answer] In some sense, almost every system of government can be equated to a dictatorship to some degree, in that it is necessary for the area and populace governed to abide by the rulings of the government in order to maintain stability. Since the question does not specify that this is a human government, I will begin by assuming a human government, then discuss the options for non-humans. Humans in small tribal societies are typically governed by groups of elders, who by their years of experience, can remember situations in the past corresponding to current situations. As settlements grow beyond a single tribe, and as trade increases in volume, it becomes necessary to keep records. It is from such a necessity for record keeping that writing is invented or imported. In the early days of a society's adventure into literacy, only a few individuals will be literate, and not necessarily the leaders. Since in this scenario, a single tribe has had an influx of people from other tribes, there would still be multiple leaders. A single leader is unlikely to arise without some sort of external stimulus such as a war, since any tendency toward dictatorial behavior would simply lead to the populace leaving for a place with a less unreasonable leadership, or removal of the would-be dictator. In the event of a war, however, it is of benefit to a society to have a single overall military leader, as this reduces the duration of the decision cycle and ensures that response times to threats are minimized. Societies that have experienced large-scale war are more likely at that point to develop a monarchy and an aristocracy based on military position, as humans tend to want to retain whatever authority they gain. In fact, outright totalitarian dictatorships amongst humans are pretty rare. It takes a strong-willed and ruthless individual to achieve and maintain such a position, and such people are often the subject of assassination attempts and rebellions, so most forms of government that remain functional over time take some notice of the opinions and needs of the population that they govern. As to alien societies, the psychology of the species must be taken into consideration. A herd-based species may have many leaders, even if they practice a form of sexual dominance, as any individual spending time becoming the dominant member of their gender is almost by definition not spending it being a good administrator. A dictator under these circumstances would be practically unthinkable. An individualistic species would have forms of government not too dissimilar from humans if they had a tendency to be gregarious, but again a dictatorship would be unlikely to arise. The traits that would most encourage a dictatorship would be a situation where the members of a species had some differences in intelligence levels, for example, if the old were much more intelligent than the young, or if there was a "brain" caste. In such a situation, the best thinker would make a natural leader. [Answer] This was covered to an extent in Diamond's "Guns, Germs, and Steel". The ruler has as much power and latitude to rule, as the economic and survival conditions permit them. E.g. in subsustence-agriculture or other resource-poor environment, there just isn't enough surplus to support a layer of "not doing anything useful for survival" ruling classes, nor to mention dictatorial methods of control (which require "muscle" to implement, who also have to be fed). As there exists more surplus, game theory says that naturally those humans with leadership abilities will try and capture that surplus - both because they think they know better what to do with it, as well as to use it as means of control (both by paying off the enforcers, and by rewarding political supporters). Would that lead to dictatorship? Depends on the species. In Earth Homo Sapient, that is a likely sceanario. * ~3% of individuals classify as socio- or psychopaths. A person like that, when they do get power, will of course be more predisposed to more dictatorial and less democratic form of government * basically, democracy is not a stable equilibrium. It's easy to slip out of it if the leadership is captured by power seeking sociopath; which is what happened to pretty much every attempt at Democracy; some faster (such as France to Communist Russia), some slower (Roman Republic, or even USA in its 2014 form; it would be seen closer to dictatorship than to a democratic republic by the Founders thanks to steady enroachment of executive power and legislative incumbency). As an alternative they fall to external forces (Athens lost to Macedonia). [Answer] There is a common opinion that relations between people largely depend on the technology owned by civilization, and revolutions mostly happen when technology advances enough to make the existing order inefficient, and the new order more efficient. Almost always, there are some social groups that loose from this transition. With enough power they may stop the evolution, or force into sub-optimal branch of evolution, for a few hundreds years. However such forced deviation from the optimal path cannot last forever. When the ruling power applies some terminal already measures to keep the hopelessly failing current state, we call this dictatorship. Hence if the new civilization starts really badly, with unsuitable personalities involved, this may create a few hundreds of "dark ages" but these will pass. ]
[Question] [ You have a mass driver which throws a 1 kg slug of iron at your spaceship. The slug reaches your spaceship and at that time it is going 30 km/s relative to the spaceship. You intend for the spaceship to harvest some of the momentum of the slug, allowing the spaceship to accelerate somewhat without spending propellant. The slug will then continue on, somewhat slower than before. What is the best way to harvest momentum from the slug? The slug must not be melted or otherwise destroyed because it is aimed so that it will eventually orbit back to where it can be caught and re-used. The catcher can't be too close to the slug because of the danger of a collision. We can suppose that the spaceship tracks the slug and maneuvers very accurately to catch it, but for safety no part of the catcher mechanism should be within 1m of the slug. A large [eddy current brake](https://en.wikipedia.org/wiki/Eddy_current_brake) might harvest some momentum from an iron slug. However, this is somewhat limited for this scenario because it turns the slug's kinetic energy into heat in the slug. Braking an iron slug from 2 km/s to 0 with an eddy current brake would unfortunately melt it. The slug has to be iron. A good solution should harvest a lot of momentum from the slug, and also should not weigh too much. We might say the entire spaceship should weigh no more than 1000 tons. [Answer] If your mass driver used electromagntic acceleration systems (eg. it was a [coilgun](https://en.wikipedia.org/wiki/Coilgun)) you can use the exact same techniques to decelerate a slug as you used to accelerate it in the first place. You're effectively treating the slug as the moving bit in a giant electric motor, and electrical motors can be run in reverse during [dynamic (or regenerative) braking](https://en.wikipedia.org/wiki/Dynamic_braking), which is not the same as simple eddy-current braking, as most of the heat will be generated in the spacecraft rather than the slug. Some heating will occur in the slug suring both acceleration and deceleration, but you can always just brake less aggressively and throw more slugs to make up for it. In the limit, this starts looking a bit like a [space fountain](https://en.wikipedia.org/wiki/Space_fountain). You can reduce heating further by using superconducting projectiles instead of dumb iron slugs, but that adds its own issues and increases the required tech-level. It is worth remembering that this sort of technique does not seem to have been considered for real-world spacecraft propulsion, and that should raise a red flag or two. If nothing else, 30km/s is fairly modest as far as fancy interplanetary travel goes, and it seems likely that a science-fictionally effective nuclear-electric rocket could outperform it (in duration, if not necessarily initial acceleration). You can see similarities with pellet-beam propulsion... [NIAC](https://www.nasa.gov/about-niac/) just awarded a phase 1 grant to some research on this: [Pellet-Beam Propulsion for Breakthrough Space Exploration](https://www.nasa.gov/general/pellet-beam-propulsion-for-breakthrough-space-exploration/). I'm more interested in stuff like [MagBeam](https://en.wikipedia.org/wiki/MagBeam) myself, but it is a somewhat more sophisticated system with lower [technological readiness](https://en.wikipedia.org/wiki/Technology_readiness_level) [Answer] Suppose you have a space elevator cable suitable for visiting small planets with no atmosphere. String is always useful. Let us assume this is buckytube cable which can lift 1000 Kg on Earth gravity. Under this tension, the cable will accelerate a 1000 ton ship at about 1 cm/s2, which would be gentle enough not to spill your tea. At the other end, this will decelerate your 1Kg slug at 1000 m/s2, which is 100 x Earth's gravity. Deceleration would take 300 seconds, or 5 minutes. With these figures, you will need 450 Km of cable. You will also have to be very careful about jerking: climbers' ropes have breaking strengths in tons force because they have to handle the deceleration when the rope suddenly goes tight. Buckytube cables are not springy so they will be vulnerable to this. The cable also has to take the strain for accelerating itself as well as the slug, and I haven't included this. I have chucked your precaution of saying no part of the catcher mechanism is to be within 1m of the slug, because I don't think it should apply here. 450 KM is a lot of cable, but not absurd if you were carrying one anyway as a space elevator. If the slug was going less fast (say 10 KM/s) you could make do with 50 Km, as this goes as the square of the velocity. Your captain can probably figure out how to do this if they look at a history website for how they cleared Earth's orbit of old, junk satellites back in the 2060's. I added a bit on avoiding the jerk in a comment, and I am now copying it here. To avoid the jerk, see 'Moby Dick': you chuck the harpoon and then let the line run through a tight grip with thick gloves. This pulls back on the target you have attached to, but not so suddenly that you break the line or pull out the harpoon. I think this proposal lies somewhere between 'pretty hard' and 'just about possible'. I think it might lose out to other schemes unless you had the apparatus for other purposes, such as an elevator, or hunting space whales. [Answer] Heat can be a source of energy, also, as it is in Stirling engines. Make your tube very long, curved if need be, and alternate your tube between eddy current braking, and "cooling" sections in which the excess heat is also captured as a source of energy. The melting point of iron is 1538C, arrange your sections to only heat the slug to 1200C, and then capture that heat long enough to reduce it to perhaps 500C, and repeat the eddy brake, then the Stirling heat capture, etc. ]
[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. [![enter image description here](https://i.stack.imgur.com/uyOLB.png)](https://i.stack.imgur.com/uyOLB.png) The lakes and the bay are formed by the rift where the right chunk is diverging away from the main plate. I've put mountains on the land part of the rift a la Ethiopia's Great Rift Valley, but should there also be mountains along the edge of the lakes/bay? Do the mountains formed by a rift go on the part of the rift that's currently over land, or should they also be on the coasts of the part that's already split away? [Answer] For the land portion of the rift there would be a rift valley with volcanic ridges on either side. For the portions in the water there will be an underwater ridge. If enough magma rises under the oceanic crust then a string of islands can appear. But this is very rare. The best example I can think of it [Iceland](https://en.m.wikipedia.org/wiki/Iceland), which sits directly on the [Mid-Atlantic Ridge](https://en.m.wikipedia.org/wiki/Mid-Atlantic_Ridge). For the shorelines you will have older mountains that are no longer volcanically active. [![The left shows a rift of a continental crust and the right is the rift of an oceanic crust](https://i.stack.imgur.com/n2laa.png)](https://i.stack.imgur.com/n2laa.png) The left shows a rift of a continental crust and the right is the rift of an oceanic crust. [Answer] This depends on what you mean by mountain. Rift valleys form a smattering of small isolated volcanoes. They occur everywhere in the area and are mostly a side effect of the upwelling mantle magma that creates the spreading finding any crack or weak point. There is also usually bit of flood basalt where the rift triple junction first formed which gets carried along by the diverging plates. The typical "mountains" of rift valleys are not really mountains as we normally think of them. just the original height sides of the rift valley which seem tall by comparison to the valley. these are called "block mountains" See below [![enter image description here](https://i.stack.imgur.com/V61s8.png)](https://i.stack.imgur.com/V61s8.png) ]
[Question] [ (Note: I am not yet sure about the population numbers involved here, but if it is a very crucial aspect of the answer, somewhere between 1 million to 100 million at the start is almost certainly correct. The tech-level when magic appears is late bronze/iron age, and technological progress is similar in order to our world, but about ~30% slower.) A group of people (a few dozen people) in my world were given the ability to access magic. The only way (as of now; I'll have to add other ways if this method is too slow) to gain the ability to access magic is if one of your parents also had that ability. This "gene" is guaranteed to pass to one's children, and doesn't get "weaker" or "diluted" if only one parent has it vs both parents had it. This "magic" is not strong but IS desirable; individual strengths vary considerably but almost all magic users can access this magic to temporarily become stronger, faster or use magic tools (though magic tools are a much later invention; they are very hard to invent) Some other points: 1. The group that gains magic originally as a founding principle wants to spread magic all over the continent. This sentiment may not be shared by those who they give it to, however. 2. One of the major religions is against this magic, but soon enough it splinters off into more moderate sects who are not. The priests and hardcore followers of this group aren't counted in "everybody" for the purposes of this question. It originally seemed to me that this method would not work and "magic" would remain confined to the nobility. But after reading that pretty much all of humanity is a descendant of Charlemagne, I think it might be possible. Is it feasible that in around 2000 years, every human (on this continent; there's nothing else that's relevant) has this "gene?" If not, is there a number of years when this is nearly guaranteed? If yes, what would be a reasonable estimate for that number of years? A clear timeline of when which group (ie nobility, then maybe rich commoners, then later peasants) gain this ability would be very helpful. This might be too story-based, though, so the main question is just the upper one. Insights would be appreciated. EDIT 1: Since someone asked, I'm providing some clarifications of the most common ways magic can be used. Not everyone can use all of these, but most users can use most of these. 1. Increase muscular strength 2. Increase the speed of perception. Essentially makes one see the world as slow-motion 3. Detect other magic users 4. Produce body heat (More of a side-effect. All magic use produces body heat but this can be exploited by intermediately skilled users to pretty much never freeze as long as they aren't too tired to do magic) 5. Produce flame. This is pretty hard as it involves controlling your body's rate of magic "combustion" to overheat a very small part, like your fingertip, then use it to heat something flammable. If done badly (or deliberately uncontrolled), a user can burst into flames or even explode. 6. Most other uses require specially designed tools. They really didn't come into play until much later, some 1500 years down the line and remained primitive for thousands of years more (mostly due to extinction level events that reduced knowledge. However, these events happened after everyone already was able to do magic) The previous mention of "extinction level events": Possibly it can be said that only people with magic survived those events. But this is not true as per my current iteration, unless no other possibility can be. [Answer] 2000 is plausible. It is not a precise science, and with initial population being in few dozens luck would play a big role, especially in the beginning. But it is not impossible. "A clear timeline of when which group (ie nobility, then maybe rich commoners, then later peasants)" - this would require some heavy assumptions about your story, you should have put better time frame and cultural background, like "similar to Europe, years 1 to 2000 with development similar to 1 to 1400". "would remain confined to the nobility" - if at least one of these people was noble or rich at the beginning, it may make it much easier for them. For the most of the period in question there was slavery, your magic cult could use it to dramatically accelerate the process. But even without it it is plausible. Especially if people consider magic desirable. With over 90% of the population working in agriculture, strengthening would have clear benefits for them. The same for warriors of all kinds, and most artisans like blacksmiths or carpenters. For nobility, a military aristocracy, it would be pretty much a must-have upgrade, much more valuable than other benefits they can get from marriage. And they would need it only once in a bloodline. The only notable class without clear benefits would be clerics. One more thing you could throw in - a better immunity for mages. Child mortality was horrific for the most of the history, even minor improvement would help a lot. I would even upgrade it to "very likely". <https://en.wikipedia.org/wiki/Jesus_bloodline>: Ultimately, the notion that a person living millennia ago has a small number of descendants living today is statistically improbable. Steve Olson, author of Mapping Human History: Genes, Race, and Our Common Origins, published an article in Nature demonstrating that, as a matter of statistical probability: > > If anyone living today is descended from Jesus, so are most of us on the planet. > > > And it was just a one guy without any special magic benefits. [Answer] The mutation would spread though heredity, so that every person who has the mutation would have to be descended from one or more of the original mutants. Jani Miettinen's answer mentions Y chromosome "Adam" that every human in descended in the male line from, and Mitocondrial "Eve" that every human is descended in the female line only. Considering how long ago those persons are calculated to have lived, Nuettinen concluded it would take hundreds of thousands of years for someone to become the ancestor all living persons. But the number of ancestors someone has X generations previously will be 2 to the X power, while only one of those ancestors will be in the pure male line and only one will be in the pure female line. Someone will have 1,024 ancestors in the 10th generation back, which will included 1,022 in mixed male and female lines of descent. Similarly, after many generations, the vast majority of a person's descendants will be in mixed male and female lines of descent. > > The age of the MRCA of all living humans is unknown. It is necessarily younger than the age of either the matrilinear or the patrilinear MRCA, both of which have an estimated age of between roughly 100,000 and 200,000 years ago.[14] > > > A study by mathematicians Joseph T. Chang, Douglas Rohde and Steve Olson used a theoretical model to calculate that the MRCA may have lived remarkably recently, possibly as recently as 2,000 years ago. It concludes that the MRCA of all humans probably lived in East Asia, which would have given them key access to extremely isolated populations in Australia and the Americas. Possible locations for the MRCA include places such as the Chuckchi and Kamchatka Peninsulas that are close to Alaska, places such as Indonesia and Malaysia that are close to Australia or a place such as Taiwan or Japan that is more intermediate to Australia and the Americas. European colonization of the Americas and Australia was found by Chang to be too recent to have had a substantial impact on the age of the MRCA. In fact, if the Americas and Australia had never been discovered by Europeans, the MRCA would only be about 2.3% further back in the past than it is.[15][16] [17] > > > <https://en.wikipedia.org/wiki/Most_recent_common_ancestor> Thus it should take only about one to three thousand years, I guess, depending on various factors, for every person on your planet to be descended from a mutant if the mutation appeared in one person. If the mutation appeared in several persons about the same time, then the descent from mutants should spread a little faster. In real life some descendants of mutants would not inherit the mutated gene, but the question specifies that all children of people with the mutated gene inherit, and so every descendant of the first group of mutants will have the mutant gene. Thus the period, about one to three thousand years, required for everyone to be descended from one or more of the original mutants would be the period for everyone to to acquire the mutant gene. [Answer] This is a bit of a social issue. In 1500, the population of Europe was around 61 million. If everyone who had the gene only married those who didn't have the gene, then you could convert the entire population in about 26 generations; less than 500 years. You could do it in less if the magi had a lower infant mortality rate, if they were selected preferentially for important jobs, etc. The problem is that humans are inherently tribal and insular. Prior to the enlightenment, this ability would have been hounded by religious leaders, who would find it threatening, and therefor against God. Anyone who married into such a group could be excommunicated or killed. It would probably start holy wars. And that's just Europe. insemination to geographic areas like East Asia and the Americas would be a lot slower, for obvious reasons. The reality is that it depends on how striking the features of someone who has the power are. Special eye color? Skin tone? Shape of the ears? Any of those would be targeted by haters, and the features would be more obvious with geographical distance. In reality, "all" people is probably "never." There are still some areas of the world that refuse to even allow visitors. You're never going to get interbreeding into those areas. There will be purist cults who try to keep it out of their blood line, right up to the point of the last untainted person. [Answer] It's all about the math... If a magic user sires (or bears) six children with non-magic users, and all those descendants do the same, then there will be just under 1.7 million descendants after eight generations. When "a few dozen" people do that, then there will be just over 60 million magic users after 8 generations: `36 x 6^8 = 60,466,176`. Problem solved!!! But no, since messy practicalities always stand in the way: * The men could certainly do that (cuckolding, etc); would the women do it? * Will all the children live long enough to reproduce instead of dying too young to have all six children? * Will the rest of the societies in the world let that happen? (Magic or not, "quantity as a quality all it's own": jihads, assassinations, etc could decimate the magic population.) * Planets are BIG, and full of mountains, deserts, jungles, oceans with fierce storms, and far away continents & islands. People live in all those places. How are your bronze-age magic workers in (for example) Mesopotamia or the Ural mountains going to even know that they have to get to the Andes mountains, the Amazon jungles, Australia, the North American Great Plains and Nunavut? Thus, given how long it took "us" to get from the Late Bronze Age to Magellan's circumnavigation (about 2,600 years) and assuming that the magic users were intrepid explorers ("Are there other people Beyond The Ocean?") then a reasonable answer would be 3,000+ years. [Answer] This basically follows the inheritance mechanics of a gene drive. A gene drive manipulates cellular machinery to bypass the normal recombination process and force all progeny to carry the gene. Early on, it will spread roughly twice as fast, because all progeny will carry it even when only one parent has it. The "natural" form will also rapidly go extinct once the majority of a population has the gene, since it will become increasingly difficult to find mates that lack it. So you will end up with populations where magic ability is universal, and any outsiders who join those populations will have children who can use magic. This still will take many generations to take over an entire population if selection is random, it might be strongly desirable to have one's children be able to use magic. If so, those without magic will strongly favor mates that do have it. This could be tweaked to favor spread even further, if children with only one magic-using parent were stronger than other magic users: then those who do have magic would have reason to prefer mates that do not have it. Such pairings will be the norm at first, but will become increasingly rare as the magic-using gene takes over. [Answer] Basically you are asking how long it takes that there are no longer children who lack that mutation. In other words, everyone is descendant of the original group with the mutation. It is assumed that [all men share a common male ancestor from whom the Y chromosome came. He is called Y chromosome Adam, and he lived probably 200,000 - 300,000 years ago](https://en.wikipedia.org/wiki/Y-chromosomal_Adam). There is also [a woman, mitochondrial Eve. She is the ancestor of the mitochondrial line our cells have. She lived 180,000 - 580,000 years ago](https://en.wikipedia.org/wiki/Mitochondrial_Eve). So, concluding from those two, it takes a very long time for a trait to dominate a whole species, and it is not even proven that something that will ever happen again. There might not be a genetic Merlin at all, and if there is, it probably takes hundreds of millennia for the gene to get spread like that. It can happen in a subpopulation in a reasonable time, but not the whole species. 2000 years is definitely not enough for it. ]
[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/241301/edit). Closed 11 months ago. [Improve this question](/posts/241301/edit) I am imagining a project where the development of more advanced brain-computer interfaces allow humans to communicate telepathically with animals, and so discover that numerous species on Earth are sapient. These include African bush, forest and Asian elephants, the common dolphin, Atlantic bottlenose dolphin, spotted dolphin, fin whale, blue whale and humpback whale. However, I have run into a problem: all these species arose either before or around the same time as humans, so I need a good excuse as to why none have also developed a high-tech civilisation, discovered fire or even developed tools beyond the level of sticks and stones. Any ideas? [Answer] They are all total a-holes. Civilization entails getting along. Humans do ok with that. None of the other sapient animals can. They are total jerks to anyone outside immediate family. Dolphins get together for reasons but they do nothing but hate on each other the whole time. Chimps eat baby chimps. You cant be around an elephant male for more than a few days before it tries to stomp you or mate with you or stomp you to slow you down then mate with you. Whales are just dicks. The fact that animals are all jerks becomes evident pretty quick to people using the telepathy. There was some suspicion that might be the case because we are familiar with cats. It turns out humans are actually the goodest or at least capable of being good to each other long enough to make civilization. --- Dogs are not jerks. Dogs are sentient too and they are sweeties. When asked why they did not develop a high tech civilization they will good naturedly point out that they did. But they could not have done it without our help! [Answer] ## No writing or tools Writing is a critical prerequisite for developing a technological society. Writing allows creatures to store information outside their bodies. Without writing, each individual can only have the knowledge they are able to hold in their memory, and that places limits on what kinds of projects individuals and societies can undertake. It also makes it much harder for society to unlock new knowledge because they can't do science if they can't record observations. None of the water creatures you name have any real ability to grip objects, a handicap that is often glossed as "they don't have opposable thumbs." Also, to the extent that technology requires taming and wielding fire, they're stuck because they can't do that in the water. Elephants do have some limited tool use, because their trunks have incredible dexterity. But, they don't have writing. Since many kinds of elephant are migratory, and have very limited ability to touch their own bodies, maintaining a collection of written materials would be difficult (though not impossible, with help from another elephant). [Answer] Maybe the answer has something to do with their underlying biology, and that they had no need to form civilizations in the first place! Dolphins and whales, for example, very likely wouldn't be able to have discovered fire considering they live underwater. Even tools like spears or the wheel and axle would have been very useless, let alone the fact that wielding them with flippers and fins would be extremely difficult. So the dolphins may have instead spent their time developing a [complex oral language](https://www.sciencedirect.com/science/article/pii/S2405722316301177) filled with rich culture and tradition! The other creatures may not have been under as much "pressure" to develop civilization as humans were. And even humans were hunter-gatherers for around [2 million years](https://www.history.com/topics/pre-history/hunter-gatherers)! The development of civilization was a relatively modern occurrence. Humans formed civilizations for [mainly agricultural and economic reasons](https://education.nationalgeographic.org/resource/key-components-civilization). Perhaps the elephants had no need for such things! Elephants are mainly herbivorous, and plants and grasses are plentiful in their natural habitat. They wouldn't have any need to farm or cook trees, and similarly, they wouldn't need advanced tools to harvest them, since their trunks already do all the work. They would have no need for mutual defense since they have no major predators! Elephants can thermoregulate extremely effectively due to their large size, and wouldn't have been under pressure to keep warm (and thus develop fire) as much as [cool off](https://phys.org/news/2013-05-elephants-hot-days.html). I hope this helps! [Answer] You forgot an extremely important group of animals that are sapient: birds. Crows/ravens and large parrots have been tested and appear to be approximately as intelligent as 4 or 5 year old humans. Why are they stalled out at that stage and have not continued to become more intelligent and technological? Part of the reason may be limited body size due to the need to fly, lack of hands for manipulating objects and short lifespans. Another group are the cephalopods (squid, octopi, cuttlefish). When tested they also show high intelligence and good tentacle dexterity. They are limited by short lifespans and being underwater. [Answer] Here are a few possible reasons that could explain why these species have not developed high-tech civilizations or discovered fire: 1. Lack of dexterity: Many of these species, such as whales and dolphins, have physical adaptations optimized for their aquatic environments, and may lack the necessary dexterity to manipulate tools or work with fire. 2. Different needs and priorities: The sapient species in question may have different priorities or ways of satisfying their needs that do not involve high technology or fire. For example, they may rely on instinct, communication, and cooperation to meet their needs. 3. Environmental factors: The environments in which these species live may not provide the resources necessary for the development of high technology or fire. For example, many whales and dolphins live in environments where fire is not feasible. 4. Different evolutionary paths: The evolutionary paths of these species may have taken them in directions that do not involve the development of high technology or fire. This could be due to differences in the challenges they faced, their physical abilities, or other factors. These are just a few possible explanations that could help resolve the issue in your project. ]
[Question] [ ([Previous Question](https://worldbuilding.stackexchange.com/questions/237319/biological-energy-dense-fuel-for-a-giant-unicellular-organism)) Recap: > > Jimmy Hopkins (yes, that's his name) is a extremely weird organism. > For one thing he is extremely large, but on the other hand, he is > extremely weird, because of one thing- He is an unicellular organism > > > You heard it right. JH is just nothing but a giant unicellular > organism about 50m across and 30m tall, resembling a giant bacterium. > JH has a extremely hard capsule made of cellulose and lignin, to > protect it from abrasions and dents. Inside JH is a collection of > thousands of chloroplasts to produce food. JH's mitochondria are > really nothing more than a bunch of oversized mitochondria that > produce a lot of energy. Since JH is so massive, it would die if it > were to exist on land, so it simply swims in the ocean. JH has > multiple flagella that are about twice as long as the host organism > itself, which help it to propel through at high speeds through the > water. In short, JH is basically an upscaled version of an > cyanobacteria, except with chloroplasts and a proper nucleus. JH is > rod shaped. > > > So Jimmy Hopkins has now found a way to propel itself (the fuel is for your imaginationツ) in times of emergency, and is now safe from its predators. However, JH now has to contend with another huge problem-Reproduction JH is a unicellular organism, so it cannot reproduce sexually, and has to therefore reproduce asexually. However there are a few problems with reproduction: * As JH is an extremely huge organism, its cell wall and capsule, despite being transparent would be over a few cm thick, to protect from abrasions, infections and dent. However, this capsule being made of cellulose and lignin, would be extremely brittle. JH trying to split apart by fission is like trying to perfectly split an egg. If done improperly, then JH will die catastrophically, as the cell wall and capsule rupture. This also risks the ignition of the "emergency fuel" it uses to escape predators, thus exploding and destroying JH. * Even if fission was done properly, there would be a chance, that one "child-cell" would end up with the flagella, while the other would end up with no flagella, risking predation * JH cannot bud like Hydra, as you cannot have a bunch of flagella growing on the "child-cell" as the cell's back is attached to the parent during maturation. This means that JH's species would go extinct if it did not reproduce. So, JH has to look for an alternative way of reproduction The question is: What type of reproduction would JH use to create offspring (without dying or ending up with deformities)? [Answer] Tiny Baby Hopkinses Jimmy Hopkins creates a bunch of microscopic unicellular babies inside its body. Then he releases them through pores in the cell wall. Jimmy Hopkins of course has loads of pores to let nutrients in and waste out. The Baby Hopkinses grow to full size over several yearses. [Answer] Spores could be released through tiny openings in the cell wall, which open when Jimmy here has to spawn. Like fish eggs, these spores could be tiny and be released en masse, with most being eaten by predators, but enough surviving to grow in macroscopic adults. [Answer] Asexual cellular fission is totally fine. You are probably overthinking the alleged issues with asexual reproduction. * the wall can be built inside the cell until it split it into two parts: no losses to the outside. Alternatively, it can be temporarily replaced by a less performing wall until the final one is synthesized. It's plausible a temporary increased vulnerability, like crustacean have immediately after changing their shell. * being an unicellular creature, it doesn't have organs, but rather molecular aggregates which can be made by decoding the appropriate genetic sequence. Getting it or not after the split is again a temporary inconvenience, nothing major. ]
[Question] [ I have read dozens of books where gravity magic is a thing. It ocurred to me, while reading one of these stories, that every version of a gravity magic spell that I have heard of, is missing something, namely they dont consider the effect of the spell on fluids in the environment like air or water. A typical example would be a spell where the caster creates a invisible plane where the acceleration due to gravity is a constant with its vector perpendicular and pointing towards the plane. This is demonstrated in the stories when the spell is cast on the ground, crushing an opponent, or horizontally throwing an opponent, etc. Realistically though, if a gravity spell was cast on the ground, the column of air over the gravitational plane would also be affected. My initial thoughts are the air column would fall and compress, which would cause the air to heat dramatically, then a vacuum would form where the air was leaving creating extremely high winds which would could eventually form a fire tornado. Where would it end though? Could it cause a fire hurricane? Would it get hot enough to vaporize rock and bore a tunnel to the Earth's core? So my question is, what effect would a gravity spell have if its plane of attraction was a 20' diameter circle placed on the ground that increased gravity in a vertical column by 1g and it could last 1min, 10min, or an hour before expiring? Edit: 1. I wasn't trying to cast shade on any other authors for their flavor of gravity magic, I just wanted to explore some possibilities. 2. This gravity magic works by adding a gravitational force to an area except instead of pulling omnidirectionally to a point it pulls unidirectionally towards a plain. The portion of any object that intersects a line perpendicular to the spells plain starting at the plain and going off into infinity in the opposite direction of the gravitational pull of the plain would be in the spells aeea of effect. The magnitude of the acceleration would fall off as the distance above the plain is increased in the same way the magnitude of acceleration due to earths gravity is reduced as you go further away from the surface of the earth. The magnitude of the force, shape of the plain and duration of the effect can be modified in the spell. For this question I restricted the spell to a 20' circle on the surface of the earth that adds 1g of acceleration in the same direction as the acceleration due to Earth's gravitational pull at that location. I also asked the effects for a 1min, 10min, and 1hour duration under the assumption the spell would cause weather effects that would be pretty different based on the spells duration. 3. I was hoping for an answer that would take into account the pressure, volume, density equation: PV=nRT, where P=pressure, V=volume, n=number of moles of gas, R=ideal gas law constant, and T=temperature. Answering that would depend on things like how the turbulent boundary layer that would form along the surface of the affected cylinder of falling air would effect the maximum pressure of that air cylinder, how doubling gravity for just that cylinder would affect the terminal velocity of the air, etc. Knowing the pressure, temperature and velocity gradients in the spells direct area of affect should also shed some light on weather affects, etc. [Answer] # Turbulence: I think you are overthinking the effects - besides the total collapse of reality as the laws of physics are broken. With an increased gravity force pulling down, you would simply achieve a downdraft. gasses in the column would be effectively heavier than the gasses around it, and they would sink. Of course, the gravity isn't affecting the pressure, so the gasses would tend to rapidly compress out of the column as the air moves down. The gasses throughout the column would pull fairly gently on the air around to fill the space as the gasses sucked in and then were blown out due to pressure. There would be almost nothing happening to the ground, except the effects of wind and turbulence. Any heat generated by friction would rapidly diffuse. Many surfaces on the Earth (like where a truck parks) experience temporary increases in weight, so ground deformation would me slight at best. It's a lot more fun if the column is the other way, but still not Earth-shaking. You would have a dirty column of air shooting upwards quite a bit like a tornado. air would be both sucked in (especially at the bottom) and blow outwards to adjust the pressure of the air in the column with the air surrounding it. At the top, near space, the pressure differences of the lower and upper columns would cause very little loss to space as the gravity tried to accelerate gasses towards space, and the denser gasses from below diffused outwards to adjust pressure. It would likely start to rotate from the Coriolis effect, and might even visually be indistinguishable from a very out-of-place tornado. Friction would generate some heat, but not enough to make a huge difference given the level of air mixing that would likely be going on up and down the column. [![enter image description here](https://i.stack.imgur.com/bQGT0.png)](https://i.stack.imgur.com/bQGT0.png) An exotic location for your column (like a lake or river of lava) might have some specialized effects, but I'll assume a more standard soil covering rock (eventually). The ground and loose soil would rocket upwards and scatter in all directions as the violently mixing air blew it out of the gravity column. but consider areas where there are tunnels and overhangs of dirt and stone. the cohesion of the matter is high enough that a fair amount of it would stay put despite the change in gravity. * Some strange chemistry might occur at the very edge of the column, as individual molecules are torn by conflicting gravity fields affecting different individual atoms. But the strength of the bonds in most molecules would likely be able to resist the effects. Still, certain types of molecules (especially very long ones) could experience exotic effects. It is entirely possible that passing in and out of the column could kill an animal, as all the molecules in its body are individually stressed by 3G's of shear (one down, two up to cancel the gravity, in the case of the reversed gravity). [Answer] It depends on whether your gravity spell pulls downwards towards a plane, downwards towards a point or (amusingly) inwards from a spherical area. 1. Gravity spell pulls downwards towards a plane. This is the simplest scenario and the one which is usually implied. If gravity is increased in a single direction towards a flat surface, air will also be pulled towards the surface but will be pushed sideways out of the area of effect by the continual torrent of air being sucked into the upper area of the spell. This means that if a person is subjected to an extra 0.5 gravity, they would also have to contend with the continual downwards flow of air with the same extra 0.5 gravity force behind it - which would essentially double the "gravity" pushdown on the person through the added continual air pressure. No odd effect with liquid in this scenario. 2. Gravity spell pulls downwards towards a point. This is where things get wonky. If you stood on a planet with 1.5\* the gravity of earth, you could easily predict the added difficulty of breathing or circulating blood in the human body as humans are essentially up/down pressure systems. If a human is pulled inwards towards a point however, you could land up with the situation where half his body (on the left of the spells center) experienced gravity towards the right while the other half of his body (on the right of the spell's center) experiences gravity towards the left. Lord knows the damage that sort of inconsistency is going to do to your internal blood flow. Additionally, if the lungs on the affected individual are near the center of the gravity well, they going to find breathing in very easy and breathing out very hard as air wants to move towards the center of the gravity but not away form it - this in comparison to simply standing on a high gravity world where breathing in and out is made equally harder. I will add though that if air is being drawn inwards towards a point this will result in the air heating up. 3. Gravity is pulled inwards from a spherical circumference. I'm not sure what to say here besides "let loose the clowns". If the gravity spell is strong enough, the ground itself should push upwards as the affected adventurer is pressed down. As the top half of the spell will be filled with air and the bottom half with compressing ground however, i think its fully possible that the compressed ground will crumble upwards (being under pressure and having no other direction to move in) and then be pushed inwards again. In this scenario, the effect of the spherical gravity spell will be to compact the target in a sphere of earth - which while cool, probably isn't an effect one would expect from this school of magic. [Answer] ## We don't really know, because gravity is not a force. Since it is tagged science based and physics - I will attempt to answer as close as possible to our current understanding of Gravity in physics terms. *Gravity is not* a force. It is the bending of spacetime towards regions of higher mass*. What does this mean? It means that all objects that have trajectories 'at rest' (ie. with no other forces acting on them) move initially linearly through spacetime coordinates. They then 'appear' to bend in space and time only as spacetime itself is bent to a region with higher mass and energy. One way to look at it is our Moon is actually travelling in a straight line because Gravity is not a Force - it is actually resting. What is happening is the Moon's trajectory 'appears' to bend around the Earth because Earth is within a region of higher mass, and thus has a bent spacetime around it such that the Moon's straight line is a now a circle (ie. an orbit). No force is acting on the Moon. No energy is being applied to it. The Earth is not 'pulling it'. The Moon is at rest and does not experience acceleration. Only if we apply rockets (ie. a force) to the Moon will it experience force. This means that on Earth, we feel heavy when we sit on a chair not because a force is pushing us down, but because the chair is instead pushing us up. The Earth and chair actually consists of atoms, each repelling each other. It is actually the electromagnetic repelling force that is causing us to 'feel' gravity, which is actually a push upwards* from our chair. So your magic of 'plane of attraction', 'gravitational force to an area', makes no sense as there is no 'attraction', there is no force due to gravity. All objects in the universe are at rest. The only forces experienced by objects are electromagnetic ones (or Strong & Weak nuclear forces too which for brevity we shall ignore). So I propose to accomplish your spell, you are in fact halving the power of the electromagnetic force in that region instead. This would reduce the repelling effect of all electrons within that region, and cause each objects trajectory to be less influenced by that force, and thus revert more to its original 'at rest' trajectory which would likely be towards the Earth, as this is a region of higher mass. Of course, this would also cause havoc with electrons and photons, and likely have profound effects in all areas of physics, not just newtonian but also including implications for particle physics interactions, nuclear physics and chemistry. To answer your question, I imagine that although objects would 'appear' to accelerate towards your magic 'plane', at the very least electrons would be less bound by their nuclei and objects affected by your field become odd indeed, being perhaps ejected. Although their trajectory would be more towards the 'ground', for 1 hour all objects may also 'explode' (although I am just guessing there - I would imagine a shower of free electrons, light and energy). ]
[Question] [ Hell turns out to be a real, physical place. It’s a physical planet. I have most of the science figured out for this literal hades, except the heat engines used in here need a cold sink—a strong one like at the [energy](/questions/tagged/energy "show questions tagged 'energy'") absorbed by the thermal decomposition of D-block oxides (CaO was considered but decomposition happens at such a high temperature I couldn't contain it). Anyway, it's a real planet. Here is where my engines need to work: It has a sun that you never see because of perpetual cloud cover. No oxygen, so no combustion engines. Ambient temperature is 420°C. The planet has everything earth does except life. There is [abiogenic petroleum](https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2008RG000270) near the surface but no coal. The planet is dead so whatever they don’t have, like liquid water or oxygenated air, they make. The planet has every inorganic natural resource they need They Make water; (Water has to be made from methane and carbon dioxide by power from windmills driving a sabatier engine). They control their habitats. (Cold air is made by air compressors.) They travel (they made trains and steam tractors). They make oxygen (natural potassium chloride solution is electrolyzed to potassium chlorate to finally generate oxygen). No question, it is Hell. But for the story, I can’t find the heat sink reaction. The only high energy endothermic reactions I can find are thermal decomposition of D-block oxides (like CaO). That’s this question. The only thing they needed for an engine was a heat sink to cool the condensation tanks. But a practical one, working at reasonable temperatures, I can’t find. Whatever it is, it goes through an endothermic chemical reaction absorbing almost half as much energy per kilogram as oxidizing anthracite releases. What is special about anthracite coal? Coal was what powered the Boulton-Watt steam engines for 200 years, and those engines were only 3% efficient. Too much info; bottom line is, engines will be 7% efficient on this planet so I only need half as much delta heat. # What decomposing metal oxide or other natural process could run their condensation tanks with a $\Delta \textbf{H}$ close to half as large as anthracite? (An endothermic reaction is a chemical process which absorbs heat energy. Ammonium nitrate and water are an example, but that is not energetic enough to run large engines) * The physics are real here. Only real naturally occurring chemical reactants can answer the question. Everything naturally occurring and inorganic on earth occurs there. * there is no magic here. Physics is all the same. * No opinions or imagined chemical reactions. * Freon or refrigerants can’t do it for vehicles. How do you condense the freon? The reaction cools and drives the condensation tank exact l’y like a steam locomotive. But here, they use the condensation stage of their steam engines to draw steam through turbines rather than drive wheels by pistons. (Yes, same concept as my horses). [Answer] Unfortunately, the most endothermic spontaneously occurring reactions that are likely to be found are things like the dissolving of ammonium nitrate in water, which consumes 321 J/g of Ammonium nitrate. Certainly there won't be any spontaneous endothermic chemical reaction which absorbs even anywhere near 1000 J/g, let alone 12,500 J/g as the OP desires, that being half of anthracite combustion's energy release of 25,000 J/g. The main problem with ammonium nitrate is that its dissolution requires liquid water to start with, and that's going to be hard to come by in the OP's environment. Considering that there is petroleum on this world, an internal combustion engine would be a better idea than a condensation steam engine. Such petroleum would likely be heavy, high-boiling-point, energy-dense compounds, since the lighter compounds would boil off readily at 420°C, meaning that the available fuel would be even more energy-dense than our automotive fuels. If there is some particular need for temperatures low enough to condense water, an internal combustion engine driving the compressor of a refrigerative heat pump might be the best way to solve this problem, but it would make for a very inefficient engine, as historic condensation steam engines were not particularly efficient. However, the lack of free oxygen is going to be a real problem. These people are pretty much out of luck, unless they could harness atomic fusion of Iron or heavier elements, which seems highly unlikely. Even if the desired highly endothermic substance was available, the environmental temperature of a mere 420°C wouldn't boil water very fast compared with a historical steam engine, which used a coal fire with a temperature on the order of 1000°C+ to boil water. Now, as a frame challenge, I propose a different solution. Instead of trying to condense water, why not boil something that boils at a temperature >420°C? Consider Sulphur. It is liquid at 420°C, and boils at 445°C. It would actually be easier to boil Sulphur in this environment than it is to boil water in a terrestrial environment. Not to mention that sulphur has a much lower specific heat than water, so it takes a lot less heat to get it hot enough to boil. Even if for some reason brimstone engines are not suitable, there may be some other substance that is liquid at the required temperature and boils at a temperature not too much higher. People probably have better things to do with liquid water than put it in an engine after all... like drinking it, and what would Hell be without Brimstone? [Answer] The best compounds will be the ones that are under investigation for thermochemical heat storage. Around 400 to 500 deg C, you have the options of Ca(OH)2, potassium oxide/hydroxide, or metal hydrides. I'd add: magnesium hydroxide as well. As [frame challenge] your scheme to get oxygen from potassium chloride is impossible (you need oxygen to make potassium chlorate, KCl contains no oxygen), you should consider potassium oxide, which actually will decompose to give oxygen. If it was present in the earth as potassium hydroxide, you'd get water out as well as some additional endothermicity. Note that most oxides and hydroxides don't decompose at one exact temperature in real life, due to bad kinetics, etc, they generally only decompose at 50 to 100 degrees above the theoretical temperature at any appreciable rate (Source: former ceramics chemist, I used to do a lot of DTG and DSC and oxide prep). This means KOH could easily persist a few metres below ground at 400, but being heated to 600 deg or so would decompose into 1/2 K + 1/4 O2 + 1/2 H2O. <https://www.diva-portal.org/smash/get/diva2:1197946/FULLTEXT01.pdf> Failing that, what the other fellow said; boil sulfur. Or aluminium. EDIT: The Shomate Equation for K2O gives -330 kJ/mol at 750K (475ish deg C) as the heat of formation, so invert it and you have +330 kJ/mol, or roughly 3.5 kJ per gram, or 3.5 MJ/kg. Potassium hydroxide will likely be double or triple that, maybe more (I'm going to bed). Sleepy calc: K2O + H2O gives 2KOH, KOH has enthalpy of formation -424kJ/mol, adjust for additional mass and it's 5ish MJ/kg. Coal will give out less energy at 750 K than at room T, probably more like 20 (total guess). So 25%. And your people get to breathe. Metal hydrides very likely higher but I'm not checking. <https://webbook.nist.gov/cgi/cbook.cgi?ID=12136457&Mask=FFFF&Units=SI> Plus walking around on pH 14 soil...that's hell. ]
[Question] [ I'm trying to create a hypothetical planet scenario, where there is a planet that has a similar atmospheric pressure to that of Earth, but in this case, it has a gas different than that of nitrogen. So far, I've found options like neon and argon. But, I'm not sure what gas to settle for. Plus, I want a scenario where the sky is a different color, instead of blue. If our atmosphere never had nitrogen, but instead had neon or argon, could life still have evolved to what it evolved to today? If so, what color would the sky be? If not, should I create a fictional elemental gas for this scenario? [Answer] Once again, the ubiquitous [atmospheric escape](https://en.wikipedia.org/wiki/Atmospheric_escape) chart needs to be broken out. It shows the sorts of gasses a planetary atmosphere might retain, given its escape velocity and surface temperature. It is a very simplistic model of atmosphere retention, but it is a reasonable starter-for-ten. [![Atmospheric escape chart, showing likely planetary atmospheric composition given escape velocity and temperature](https://i.stack.imgur.com/EUCiA.png)](https://i.stack.imgur.com/EUCiA.png) The problem with neon and argon is that they are monatomic gasses, and as such they have a relatively low molecular weight... about 20 and 40 amu, respectively. The nitrogen and oxygen that makes up Earth's atmosphere comes in forms with molecular weights of about 38 and 32 amu respectively. You can see from the diagram that Earth is comfortably above the green band, and as such oxygen and nitrogen in the atmosphere can be reasonably expected to hang around for timescales of many billions of years. The blue band though is a little more lightweight, which means it has a much shorter escape timescale. What this means is that atmospheric neon is very hard to hang on to. Neon's low molecular mass and boiling point mean that you would need a pretty massive world in order to provide a deep enough gravity well to hang on to it, and world that big are likely to develop into wet [super-Earths](https://en.wikipedia.org/wiki/Super-Earth) or [gas dwarfs](https://en.wikipedia.org/wiki/Mini-Neptune). Argon is much more workable, and indeed Earth's atmosphere is already about 1% argon. The problem is relative chemical abundance. You can look at a table of [elemental abundances in the solar system](https://en.wikipedia.org/wiki/Abundances_of_the_elements_(data_page)#Sun_and_solar_system), and see that argon is something like 30 times less common than nitrogen. Combine that with its unwillingness to form non-volatile compounds, and you can see that getting an atmosphere's worth of the stuff without also having several atmosphere's worth of nitrogen is going to be challenging. Not impossible by any stretch of the imagination, but you're going to have to work a bit to explain it. > > if our atmosphere never had nitrogen, but instead had neon or argon, could life still have evolved to what it evolved to today? > > > AlexP's comment and "Escaped Lunatic"'s answer covers this well enough. Nitrogen is chemically very important for life on Earth (no nitrogen means no [amino acids](https://en.wikipedia.org/wiki/Amino_acid) which means no proteins). That's not to say that an alternate form of life could have arisen without it, but given the relative abundance of nitrogen vs argon it would be surprising. If you have an explanation of why nitrogen removal from the atmosphere is so effective then you can handwave in lifeforms that include lots of nitrogen chemistry just fine. Maybe it the weird atmospheric balance has a biological explanation. You'd still have the issue of things like [denitrifying](https://en.wikipedia.org/wiki/Denitrification) organisms, but maybe some kind of highly efficient and common [nitrogen fixing organism](https://en.wikipedia.org/wiki/Nitrogen_fixation) is enough to prevent gaseous N2 from escaping into the atmosphere in significant volumes. The hands are yours to wave here. > > If so, what color would the sky be? > > > Given Earthlike pressures and densities (which you'll basically have with an Argon/Oxygen main mix) and a Sunlike star, the sky will be more or less the same colour as it is on Earth. Argon has a very similar [Rayleigh scattering cross-section](https://en.wikipedia.org/wiki/Rayleigh_scattering) to nitrogen, and so the resulting color of the sky will be slightly different to Earth, but not dramatically so. Neon is probably more different, but I can't find any good information that would inform exactly what that difference would look like. Given that the color will still be dominated by the spectrum of light from the primary star, and Rayleigh scattering is strongly wavelength dependent, the color will inevitably still be "basically blue". If you want different colors, you should probably get a different star, or change your atmospheric pressure and consult the excellent chart in [this question](https://worldbuilding.stackexchange.com/q/100411/62341). A radically different gas mix would also work, but gravity and toxicity will mean that it isn't going to be very human-friendly. Note that there are other colorful effects that you can get from alternate atmospheres... [electrical discharges](https://en.wikipedia.org/wiki/Gas-discharge_lamp) such as lightning can be different. This would be very marked for a neon-rich atmosphere (red lightning!) though it is unlikely to be dramatically different for argon, which will look basically like lightning in a nitrogen-rich atmosphere. > > If not, should I create a fictional elemental gas for this scenario? > > > That's strictly in the realms of very soft scifi. You can feel free to make stuff up if that's what you want and what your story needs, but it is a long stride away from plausibility. If you want to remain within spitting distance of science in your fiction, you probably shouldn't invent new elements that are so common you get whole atmospheres made of them but which somehow haven't been discovered on Earth and don't slot into the periodic table anywhere sensible. [Answer] I believe you could get by with most of the nitrogen being replaced by Neon or Argon, but even though Earth life is mostly Hydrogen, Oxygen, and Carbon, a certain amount of Nitrogen is mandatory. So, if you want to visit such a world, take off your helmet, and go sight seeing, have fun. Want to try to set up an ecosystem for Earthly life without importing insane amounts of Nitrogen based fertilizers every year, please take videos so it can be featured in an upcoming episode of Failed Colonies. I'm not an expert, but I think you could get by with less than 5% Nitrogen in the atmosphere. If there's no native life, you'll need some sort of excuse for having enough Oxygen to breath. Blame it on a yet-to-be-explored inorganic geochemical process around deep sea hydrothermal vents and not too many readers will complain. I'm not sure what color sky you'll end up with. Let's hope for something interesting. [Answer] No plant life, no animal life Animals live on plants. Without plants, animal life cannot sustain because: * Plants are used as food * Plant produce oxygen Plants need nitrogen Nitrogen is an essential nutrient for plant growth, development and reproduction. Nitrogen is a major component of chlorophyll, the compound by which plants use sunlight energy to produce sugars from water and carbon dioxide and produce oxygen. The Nitrogen Cycle As explained [here](https://www.cropnutrition.com/nutrient-management/nitrogen): Nitrogen can go through many transformations in the soil. These transformations are often grouped into a system called the nitrogen cycle, which can be presented in varying degrees of complexity. [![enter image description here](https://i.stack.imgur.com/476do.png)](https://i.stack.imgur.com/476do.png) Argon and neon are non-reactive gases Argon and neon cannot play any role in sustaining life as they are non-reactive. [Answer] Short Answer: There are many possible changes to the composition of an atmosphere which would not change the color of the sky. It is possible that some changes in atmospheric composiiton might affect the color of the sky, but I am not familiar with them. Here is a link to many questions and answers about the color of alien skies. I typed "sky color" in the "search worldbuilding" section of the black bar at the top of the worldbuilding screen. [https://worldbuilding.stackexchange.com/search?q=sky+color](https://worldbuilding.stackexchange.com/search?q=sky%20color) Possibly some of the answers will mention changes in atmospheric composition which might result in changes in sky colors. The good news, found in my long answer, is that it is possible to make considerable changes to Earth's atmospheric composition while it remains breathable. Long Answer: What is the atmospheric composition of Earth at sea level? Dry air is 78.084 percent nitrogen, 20.946 percent oxygen, Argon 0.934 percent, Carbon Dioxide 0.0416 percent, Neon 0.001818 percent, Helium 0.000524 percent, Methane 0.000187, and Krypton 0.000114 percent. The atmosphere usually has between 0.0 and 3.0 percent water vapor. <https://en.wikipedia.org/wiki/Atmosphere_of_Earth#Composition> There are many lifeforms on and in Earth that can life without that specific atmosphereic composiiton. But if your story involves people from Earth breathing the air of the planet, or beings with similar enviromental needs living on the planet, you need to make sure the atmospheric composition is similar enough. Actually Earth life has existed in a radically different than the present one, and helped to make the present atmosphere. Earth life goes back 3 billion years, or e maybe even 4 billion years. It evolved in the second atmosphere of Earth, containing carbon dioxide and inert gases from vulcanism. When photosythetic organisms evolved, they emitted oxygen, eventually producing oxygen faster than it could be removed from the atmosphere by oxidation of minerals. The third atmosphere resulted from the large amounts of oxygen in the atmosphere. There was enough oxygen in the air for multicelled animals since about 600 million years ago. > > The average atmospheric pressure at sea level is defined by the International Standard Atmosphere as 101325 pascals (760.00 Torr; 14.6959 psi; 760.00 mmHg). > > > <https://en.wikipedia.org/wiki/Atmosphere_of_Earth#Pressure_and_thickness> A mmHG is a millimeter of mercury. In Habitable Planets for Man, 1964, Stephen H. Dole discuss the atmospheric requirements of humans on pages 13 to 19. <https://www.rand.org/content/dam/rand/pubs/commercial_books/2007/RAND_CB179-1.pdf> On page 19 he 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 doxide with an inspired partial pressure roughly between 0.05 and 7 millimeters of mercury. In addition, 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. > > > In addition, a habitable planet would have lot of water and some water vapor would be needed for rain and to keep human airways from drying out. Since an Earth atmosphere at sea level has a pressure of 760 millimeters of Mercury, and the combined limits of oxygen and carbon dioxide for humans are about 60.05 to 407 millimeters of mercury, the atmopshere of your planet needs about 353 to 699.95 millimeters of mercury to have Earth's atmosphere density. Are there any gases which would be harmless to humans at such pressures. According to table 2 on page 16, humans can tolerate up to 7 mmHG of carbon dioxide, 160 mm of Xenon, 350 mm of Krypton, 1,220 mm of Argon, or 2,330 mm of nitrogen. So a combination of 353 to 699.95 mmHG of various inert gases should be breathable. It is unfortunate that the question requires the elimination of Nitrogen from the atmosphere (except for the amount needed by plants). In addition, the tolerable pressure of neon could be as high as 3,900 mmHG, and the tolerable pressure of helium could be as high as 61,000 mmHG. To select the most desirable elements for the atmosphere of your planet, there are several factors that can be used to rank them. Ranked by how much humans can tolerate, helium would be the big winner, followed by neon, nitrogen (excluded except for a small amount), and argon if only a single gas is in the atmosphere, while some krypton and Xenon could be mixed in with other gases. Ranked by their relative abundance in Earth's atmosphere, and thus the relative ease of increasing their abundance in a slightly different world, they are argon, neon, helium, and krypton. Ranked by their relative abundance in the universe, helium is first, followed by neon, argon, kyrpton and xenon. They can also be ranked from the heaviest to the lightest gases. The heavier an atom or molecule is, the slower it will move at any specfic temperature, like the temperature in the exosphere of a planet,the outermost atmosphere where gases escape into space. On pages 34, and 35, Dole discusses the escape velocity a world needs to retain a gas in its atmosphere for geologic periods of time. There are formalas to calculated the time it takes for the amount of gas to drop to 0.368 of its orginal amount, relative to the ratio of the escape velocity of the world divided by the root-mean-square velocity of the gases in the exosphere. Table 5 on page 35 shows that if the ratio is one or two, the amount of gas will reduce to 0.368 of the starting amount instantly. If the ratio is 3, the amount of gas will reduce to 0.368 of the starting amount in a few weeks. If the ratio is 4, the amount of gas will reduce to 0.368 of the starting amount in several thousand years. If the ratio is 5, the amount of gas will reduce to 0.368 of the starting amount in about 100 million years. If the ratio is 6, the amount of gas will reduce to 0.368 of the starting amount in an infinite time. In descending order of atomic weight and thus the ability of a world to retain them in its atmopshere, they are xenon, krypton, argon, neon, and helium. Argon and neon might be the best overall candidates for the atmosphere of your planet. Because Helium is so much more abundant than any other of the gases, it might be the most likely for a planet to retain a lot of - if the planet has a high enough esape velocity. Uranus is the planet with much helium in the atmosphere that has the lowest escape velocity, 21.29 kilometers per second, as compared to Neptune's 23.71, Saturn's 35.49, Jupiter's 59.54, and on the other hand Earth's 11.186. But Uranus also has a lot of hydrogen in its atmosphere. Hydrogen is noted for burning in the presence of oxygen to produce water, so there should be only tiny trace amounts of hydrogen in your planet's atmosphere. Thus an escape velocity between Earth's 11.186 kilometers per second and Uranus's 21.29 kilometers per second would be indicated tofor your planet to retain a lot of helium in the atmosphere. I note that Earth's escape velocity is sufficient to retain helimum 4 much better than the lighter isotope helium 3, and that the complex processes which add and subtract atmospheric helium ae not well known. And of course the giant planets are are much farther from the Sun than Earth and thus would lose helium much faster if they were at Earth's distance from the sun. On page 53 Dole stated that since he belived humans wouldn't want to live on a world with a surface gravity higher than 1.5 times Earth's surface gravity of 1 g, the maximum mass of a human habitable planet would have about 2.35 Earth mass, 1.25 Earth radius, and an escape velocity of 15.3 kilometers per second. In "Exomoon Habitability Constrained by Illumination and Tidal Heating", Rene Heller & Roy C. Barnes (2013) also discuss the mass range of habitable worlds - in this case worlds habitable for any type of liquid water using life, not just for humans. On page 20 they write: > > Above a critical mass, the dynamo is strongly suppressed and becomes too weak to > generate a magnetic field or sustain plate tectonics. This > maximum mass can be placed around 2M4 (Gaidos et al., 2010; Noack and Breuer, 2011; Stamenkovic´ et al., 2011). > > > 2M4 means 2 times the mass of Earth. So if this is correct your planet should need to have no more than about 2 times the mass of Earth. Earth has a radius of 6,371 kilometers. A planet with 2 times the mass of Earth and 1.3 times the radius would have a surface gravity of 1.18 g and an escape velocity of 13.874 kilometers per second. A planet with 2 times the mass of Earth and 1.2 times the radius would have a surface gravity of 1.39 g and an escape velocity of 14.44 kilometers per second. A planet with 2 times the mass of Earth and 1.1 times the radius would have a surface gravity of 1.65 g and an escape velocity of 15.083 kilometers per second. A planet with 2 times the mass of Earth and 1.0 times the radius would have a surface gravity of 2 g and an escape velocity of 15.82 kilometers per second. <https://philip-p-ide.uk/doku.php/blog/articles/software/surface_gravity_calc> <https://www.omnicalculator.com/physics/escape-velocity> And an escape velocity in that general range is probably about as large as a habitable planet could have. And maybe that would be high enough for a planet warm enough for liquid water using life to have an atmosphere rich in helium. If not, you would have to go with an atmosphere rich in noble gases, preferably argon and neon, which are somehow many times more common than they are in Earth's atmosphere. ]
[Question] [ This question already has answers here: [What would make a sky appear purple during the day?](/questions/17815/what-would-make-a-sky-appear-purple-during-the-day) (10 answers) Closed 2 years ago. I'm a fantasy author. I'm thinking about the setting in my next novel having something to do with a world that has purple skies during the daytime. I'm wondering how could this be done from a realistic standpoint? I was potentially thinking about having the planet I'm creating have a moon that revolves around it that emits a dark blue light, but I'm not sure if this would have the desired effect. [Answer] ### The Rayleigh-scattering solution Your chance to make it work naturally is to accept [violet](https://en.wikipedia.org/wiki/Violet_(color)) (a pure spectral color) instead of purple (a mix of red and blue). Since it is a shorter wave length than blue, it will be Rayleigh-scattered stronger than blue. So your problem is to make the violet intensity in the light spectrum of your star higher than the intensity of the blue. Which is quite simple to do: just move the temperature of the star by 700-1000K above the Sun's one. [![enter image description here](https://i.stack.imgur.com/XhKCO.png)](https://i.stack.imgur.com/XhKCO.png) You'll have some side effects with a star hotter that Sun, so you'll probably need: * a thicker atmosphere (good, more medium to scatter that light. Be careful tho' with the greenhouse effect) and * a decent planetary magnetic field - good, now you can have some violet at night too in more extended aurorae (you'll have some green too if you have an Earth-like atmosphere composition)[![enter image description here](https://i.stack.imgur.com/1oNpq.jpg)](https://i.stack.imgur.com/1oNpq.jpg) (image found using image google search, [original source](https://www.syfy.com/syfy-wire/shimmering-purple-aurora-after-powerful-solar-storm), credited to Brad Goldpaint, apparently you can buy it in hi-res or printed from [here](https://store.goldpaintphotography.com/The-Night-Sky/i-SnGdzsf/A) - I'm not affiliated). --- By the way... ummm... "the visual perception is in the eyes of the beholder" - which may be more sensible for green/blue than for violet. Look, [some say that the Earth's sky is actually violet](https://www.forbes.com/sites/briankoberlein/2017/01/11/earths-skies-are-violet-we-just-see-them-as-blue/?sh=366553e2735f), we just see it as blue, because of the spectral sensitivity of the dyes our retina cells use. > > But if that's the case, why isn't the sky violet? Sure, blue light is scattered more than red or green, but violet light has an even shorter wavelength, so violet should be scattered more than blue. Shouldn't the sky appear violet, or at least a violet-blue? It turns out our sky is violet, but it appears blue because of the way our eyes work. > > ... > > We don't see the greenish hue, however, because of the sky's violet light. Violet is scattered most by Earth's atmosphere, but the blue cones in our eyes aren't as sensitive to it. While our red cones aren't good at seeing blue or violet light, they are a bit more sensitive to violet than our green cones. If only violet wavelengths were scattered, then we would see violet light with a reddish tinge. But when you combine the blue and violet light of the sky, the greenish tinge of blue and reddish tinge of violet are about the same, and wash out. So what we see is a pale blue sky. > > > ### The colored atmosphere solution Purple aerosols - not a lot that can stay in the atmosphere for long, at least not in the Earth-like conditions What can we use/handwave: 1. higher ambient temperature and high concentration in purplish elements/substances in the atmosphere - for example, iodine (triple point - were vapours can coexist with liquid/solid form - at 113.5C. A tad hot, but with a high atmospheric pressure it still may lead to life of the planet - [halo](https://en.wikipedia.org/wiki/Halophile)-[thermo](https://en.wikipedia.org/wiki/Thermophile)-philes aren't impossible) 2. endemic purplish material of biogenetic origin - like some spores or pollen of a life form (or more) that's endemic on the planet. Will probably need close to circular orbit around the star and low planetary tilt to exclude strong seasonal variation (which can put a pause on the life of the purple-something generation) 3. in an ocean world, they'll call "sky" the surface of the water - there are lots of substances that have a purple color in solution, but the bad new is the light won't penetrate too deep inside the ocean) 4. I wouldn't bet for volcanos as a source of purple aerosols, tho', at least not for creating a long-lived and planet wide purple haze in the atmosphere Finally, as tongue-in-cheek alternative, is may be a planet which's population loved so much Prince they geo-engineered their planet's weather in a perpetual [Purple Rain](https://www.youtube.com/watch?v=bm03wqLY3Nc) [Answer] The colour of the sky on Earth is blue due to [Rayleigh scattering](https://en.wikipedia.org/wiki/Rayleigh_scattering). This means that unless the incoming light is mostly purple, you're not going to get a purple sky. Now... all is not necessarily lost. Mars has a reddish sky because of its load of reddish airborne dust. If you could find a way to have your world's atmosphere contain a significant amount of airborne purple dust, you'd have your purple sky. [Answer] Short Answer. It might be possible for stars that emit more violet light than the Sun to have habitable planets, where the daytime sky might be more violet colored than blue. The star of a habitable palnet might have a ring of dust particles that absorb ultraviolet light from the star and re emit it as violet light, and that might possibly color the day time sky more violet than Earth's sky. A habitable planet in another star system might possibly have a ring of dust, and that dust might poossibly be heated by the star and emit violet light, which might possibly color the daytime sky of the planet more violet than Earth's sky. A habitable planet should have some dust in its atmosphere, and if that dust is purple colored it might refelct enough light to possibly make the day sky appear more purple than Earth's does. The star and planet might be passing through a nebula, and that nebula could reflect starlight from the star onto the planet. But It seems improbable that the nebula could be bright enough to change the color of the night sky, let alone the day sky. A planet habitable for some lifeforms, possibly even habitable for lifeforms with similar requirement to humans, could possibly have a thinner atmosphere, which like the atmosphere of Earth at hight altitudes, was a much deeper blue, perhaps a purplish blue color. Long Answer: Part One of Seven: A Star Emitting More Violet LIght. Adrian Colomitchi suggested that a violet sky could come from having a star which emitted much more violet light than the Sun does, thus causing violet light to be scattered in every direction by air particles andmaking the skay appear violetinstead of blue. > > Since it is a shorter wave length than blue, it will be Rayleigh-scattered stronger than blue. So your problem is to make the violet intensity in the light spectrum of your star higher than the intensity of the blue. Which is quite simple to do: just move the temperature of the star by 700-1000K above the Sun's one. > > > The Sun is a G2V type star with a surface temperature of 5,772 degrees Kelvin. So making the star 700 to 1,000 degreees K hotter than the Sun would give it a surface temperature in the range of 6,472 to 6,772 degreees K. Spectral class F6V stars have 1.16 times the mass of the Sun and a surface temperature about 6,400 K, while spectral class F5V stars have 1.20 times the mass of the Sun and a surface temperature of about 6,545 K. Spectral class F4V stars have 1.23 times the mass of the Sun and a surface temperature about 6,690 K, while spectral class F2V stars have 1.31 times the mass of the Sun and a surface temperature of about 7,040 K. <https://en.wikipedia.org/wiki/F-type_main-sequence_star> So according to Adrian Colomitchi's suggestion a star in that range should have the right surface temperature to emitt more violet light than blue light, and thus make the skies of the planet appear violet instead of blue. The Earth is about 4.6 billion years ago, and didn't have an oxygen rich atmosphere that humans and life formes with similar requirements could breath until about 500 to 600 million years ago, and thus 4 billion years after the planet formed. If the story requires the planet to be habitable for humans or lifeforms with similar requirements, the planet will have taken billions of years to tobecomehabitable for them. And the star willhave had to stay on the main sequence with fairly steady luminosity for those billions of years. Thus the star will have to have a spectral type which can stay on the main sequence for enough billions of yeears. [Unless, of course, in the story an advanced civilization terraformed the planet some time ago, giving it a breathable atmosphere before the planet wuld have developed one naturally} Someone objected that a star hot enough to emit so much violet light would not last long enough on the main sequence to become habitable, and Adrian Colomitchi said that a star with 1.2 times the mass of the Sun (an F5V according to the table) would last for 6.34 billion years, which would be long enough. The only scienctific study about planetary habitability for humans (and bengs with the same requirements) in particular, instead of liquid water using life in general, is Habitable Planets for Man, Stephen H. Dole, 1964. On page 68 Dole says: > > The only stars that conform with the requirement of stability for at least 3 billion years are main sequence stars hving a mass less than about 1.4 solar masses--spectral types F2 and smaller--although the relationship between mass and time of residence on the main sequence is probablyy not known with great accuracy and is subject to futue revision (see figure 25). > > > I note that Dole says that a star with a lifetime onthe main sequence of 3 billion years would have 1.4 times the mass of the Sun and would be an F2V type star. But the table in Wikipedia (which doesn't give the stellar lifetimes) lists a star with 1.4 times the mass of the Sun as an F0V, and a star with 1.31 times the mass of the Sun is listed as an F2V. Any writer who wants to make the star of a human habitable world as hot and luminous as possible should investigate that descrepancy, and look up the latest information on how long stars of different spectral classes remain on the main sequence. So it seems possible that a main sequence spectral class star less massive than F0or F2 might remain on the main sequence for at least 3 billion years and thus possibly have a planet which has already became habitable for humans (or being swiht similar environmental requirements). But some scientists don't think that it is possible for spectral class F stars to have habitable planets. They think that their increased ultraviolet light could prevent life for developing or kill off life osono afterit develops. And they think that because a F class star spends less time on the main sequence it will grow hotter faster than a class G star, and thus that its circumstellar habitable zone will migrate outwards from it faster, which could mean that planets would not spend enough time in the habitable zones of class F stars. Here are links to several discussions of the potential habitability of planets orbiting spectral class F stars. <https://www.space.com/25716-alien-life-hotter-stars.html> <https://www.centauri-dreams.org/2014/03/27/habitability-the-case-for-f-class-stars/> <https://www.cambridge.org/core/journals/international-journal-of-astrobiology/article/abs/habitability-around-ftype-stars/81D15083AD92F0812773776298681905> <https://www.sciencedaily.com/releases/2014/03/140325133544.htm> So a writer who wants to give a habitable planet a purple or violet sky will have a problem with making the star hotter and emitting more violet radiation than blue radiation. Some more cautious writers might want to avoid putting habitable planets in orbit around and class F stars, and other might want to only use less massive and cooler class F Stars. Part Two: A Star With a Ring of Dust. I note that if the star in the system happens to be surrounded by rings of dust, that dust might absorb ultraviolet radiation and reemitt as violet radiation. That might possibly increase the amount of violet radiation the planet receives from its star. Part Three: A Planet With a Ring of Dust. And it is possible that the planet could have a ring of particles around it. And possibly the particles absorb ultraviolet radiation from the star and then emitt violaet radiation, which would increase the amount of violet radiation the planet receives. Part Four: A Planet With Purple Dust in the Atmosphere. And possibly the planet has dust in its atmosphere, as all Earthlike planets do, and possibly that dust is all violet colored and thus reflects violet light into the sky. And possibly that might increase the amount of violet light in the sky of the planet. Part Five: A Planet Travelling Through a Nebula. And possibly the star system happens to be travelling through a nebula. And possibly that nebula looks a lot like a nebula in a science fiction movie or tv show had is thick and obapuge and reflects a lot of varicolored light. And maybe this nebula happens to be puble colored. So the sky of the planet might look purple at night, and manybe even in the day if the light reflected from the nebula is bright enough. But movie and tv nebeulas are not realistic. They are based on astronomical photographs which show dense, opague, colar nebulas. And despite the old saying, those astronomical photographs lie. At least those photographs deceive people who don't realized that they are taken with hours long exposures though telescopes which are ketp constantly turning lsightly to keep the nepublas in the view. The human eye usually processes 10 to 12 images per second. So each image you see has the brightness level of light which has accumulated for only 0.083333 to 0.1 secondexposure time. There are 3,600 seconds during an hour. So a photograph exposed for an hour would recieve about 36,000 to 43,200 as much light on each picturee elelement as a human eye lookign at the same picture would receive while sensing one image. So an astronomical photo of a nebula exposed for several hours would receive over a hundred thousand times as much laight as you wuld see in each image looking at the nebula though the same telescope. Nebulas seen by the human eye through a telescope are very delacate, almost transpartent, and pale. They look nothing like photos of nebulas exposed for hours at a time. So if a fictional solar system is close to a nebula, the nebula would be visible at night as a pale and delicate wonder, but it probably wouldn't be bright enough to lightened the night sky from black to purple. And since daylight on the planet would be tens or hundreds of thousands of times as bright, the nebula light probably wouldn't be enough to make the color of the day sky change. Part Six: A Planet With a Thinner Atmosphere Than Earth. If you look at the sky on a clear day, you will see that it is lighter and paler near the horizon and gets brighter and bluer higher in the sky, until it is very blue at the zenith. That is because when you look toward the horizon you are looking through a greater distance of thick air, wich catters the sunlight more. But the air gets thinner with height. So as you look stright up your a looking through a thin layer of the thickest air, then a thin layer of slightly less thick air, and then a thin layer of even less thick air, and so on. The total amount of air you see scattering sunlight above you is less than when you look horizonatally toward the horizon. Pictures taken at the peak of Mount Everest show a blue sky low down at the horizon and a darker and darker sky above the horizon. At the peak of Everest more than half o the atmosphere that scatters light is below, not above. The peak of Mount Everest has an altitude of 8,848.86 meters, or 29,031.7 feet, above sea level. And the skylooks darker and more black from there than from lower altitudes. I guess some people might possibly say that the sky looks more purple from the peak of Everest. The peaks of Mount Everest and some of the other tallest mountains in the world are in what mountaineers call "the death zone", above about 8,000 meters or 26,246.72 feet. Most climbers in the death zone breath bottled oxygen, and most of them start using the bottled oxygen way below the death zone. And even using bottled oxygen, many climbers suffer from the thin air on high peaks. People born at higher altitudes can go higher without bottled oxygen than people born at sea level. People from the high Tibetan plateau and the high Andes have the most tolerance for low oxygen levels. And people can train themselves to breath in thinner and thinner air in preparation for living and working in the higest towns and villages in the world, and for climbing tall mountains. In fact, some mountaineers have performed the fantastic feet of climbing to the peak of Everest safely without bottled oxygen, and the even more fantastic feat of climbing back down the mountain safely afterwards without bottled oxygen despite their fatigue. But people who try climbing Mount Everest without bottled oxygen have a survival rate which is much smaller than the survival rate of those who try to climb with bottled oxygen, and the survival rate of those who use bottled oxygen is not a very good one itself. So that makes me think that if a group of people from Earth settled a planet with a slightly thinner atmosphere, their descendants would gradually adapt over generations to function as well there as we do on Earth. And if after many generations some of their descendants settled a planet with a even less dense atmosphere still, they would adapt after many generations to function just as well there as well we do on Earth. And so, after settling many successive planets with succesivly slightly less dnsse atmospheres, and spending generations on each planet to adapat, a group of human descendants might possibly be able to settle a planet where the typical atmospheric density was similar to that at the peak of Everest, and where the sky was darker than on Earth, a dark blue or maybe a dark purplish blue color. > > Insects can fly and kite at very high altitude. In 2008, a colony of bumble bees was discovered on Mount Everest at more than 5,600 metres (18,400 ft) above sea level, the highest known altitude for an insect[citation needed]. In subsequent tests some of the bees were still able to fly in a flight chamber which recreated the thinner air of 9,000 metres (30,000 ft).[12] > > > Ballooning is a term used for the mechanical kiting[13][14] that many spiders, especially small species such as Erigone atra,[15] as well as certain mites and some caterpillars use to disperse through the air. Some spiders have been detected in atmospheric data balloons collecting air samples at slightly less than 5 km (16000 ft) above sea level.[16] It is the most common way for spiders to pioneer isolated islands and mountaintops.[17][18] > > > Some birds have been recorded to fly above 8,000 meters or 26,246.72 feet. They include the alpine chough at 8,000 meters (26,500 feet) on Everest, whooper swans at 8,200 meters (27,000 feet) over northern Ireland, bar-headed goose at 8,800 meters (29,000 feet), the common crane at 10,000 meters (33,000 feet) over the Himalayas, and Ruppell's Vulture at 11,300 meters (37,100 feet). <https://en.wikipedia.org/wiki/List_of_birds_by_flight_heights> So birds, multicelled animals who need oxygen to live, are able to fly at about the peak of Mount Everest, where the sky is much darker than at sea level. So alien lifeforms should be able to adapt to a planet where the atmosphere is a thin as on the summitt of Everest, and the sky is much darker than at sea livel on Earth. Part Seven: Conclusion. Obviously someone could try a combinatin of several of the suggested methods to make the daytime sky of the planet more violet or purple than that of Earth. I note that such a planet could be approximately as habitable for Earth humans as Earth is, except for the method of the lanethaving a much thinner atmosphere than Earth. Such a world could be a lot different from worlds with purplish skies for other reasons. And I could imagine a story where someone comes from a world with a purplish sky because its star emits more violet light than the Sun does, and they crash on some unexplored pplanet. They see thorugh the viewscreen or porthole that the planet has a purplish sky like their home world, and assume it has a similar atmosphere to home. So they go out the airlock without testing the atmosphere and gasp for air because this is a world where the sky looks purplish because the air is much thinner than on their home planet. ]
[Question] [ Closed. This question is [off-topic](/help/closed-questions). It is not currently accepting answers. --- You are asking questions about a story set in a world instead of about building a world. For more information, see [Why is my question "Too Story Based" and how do I get it opened?](https://worldbuilding.meta.stackexchange.com/q/3300/49). Closed 8 months ago. [Improve this question](/posts/218108/edit) In my story, mythical humanoids secretly live amongst humanity in modern day, but not all of them are created equal when it comes to blending in with the human race. While individual humans do know about them, any secrecy leak that alerts wider society is punished with death by the memory-wiping creatures responsible for maintaining the secret. Vampires and werewolves have it pretty easy, while elves maybe have to use weird hats or hairstyles to hide their ears. Others have to come up with very convoluted excuses for the ways they need to dress, or have to be fully covered. And then there are some, like arachne, that are so blatantly non-human there's just nothing they can do but not be seen. In that context, I've been thinking a bit about hooved creatures, like satyrs and minotaurs. Specifically how they might be able to conceal their legs. The hooves you could maybe hand-wave with special shoes, but... due to having hooves, they also as a result have what appear to be double-jointed legs: [![enter image description here](https://i.stack.imgur.com/0dKWN.jpg)](https://i.stack.imgur.com/0dKWN.jpg) Put pants on those things, and it isn't going to matter. Anyone even slightly paying attention would know legs don't bend like that. Now, of course, they could pretend to be wheelchair-bound and maybe have a cloth cover over their legs so nobody sees them, but... my gut is telling me there might be a more clever option than that. What would be the least awkward/conspicuous way for someone with ungulate legs to conceal that fact in public? [Answer] Long and loosely fitted skirts reaching to the ground can conveniently hide the feet. [![enter image description here](https://i.stack.imgur.com/QpAUR.jpg)](https://i.stack.imgur.com/QpAUR.jpg) As long as only the bottom of the shoes is visible, the legs are covered In Eco's Baudolino the protagonist falls in love with what he thinks is a woman, without realizing she is a satyr until the moment he goes under her skirt, which up to that moment covered her anatomy. [Answer] Big Baggy Pants. Wear stylish trousers so no one can see the anatomy of your legs. [![enter image description here](https://i.stack.imgur.com/flj0f.jpg)](https://i.stack.imgur.com/flj0f.jpg) [![enter image description here](https://i.stack.imgur.com/Xe3Um.png)](https://i.stack.imgur.com/Xe3Um.png) [![enter image description here](https://i.stack.imgur.com/ZOF4J.jpg)](https://i.stack.imgur.com/ZOF4J.jpg) [![enter image description here](https://i.stack.imgur.com/5dKyq.png)](https://i.stack.imgur.com/5dKyq.png) [![enter image description here](https://i.stack.imgur.com/DIObu.jpg)](https://i.stack.imgur.com/DIObu.jpg) [![enter image description here](https://i.stack.imgur.com/E5Uaw.jpg)](https://i.stack.imgur.com/E5Uaw.jpg) Those are supposed to be baggy pants! . . . BAGGY! [Answer] They should have specially made boots, today's fashion widely advertises them at fashion shows, so they can be hidden with customized designs. But your ungulates also have a smell, which is a problem among mortals because they have a keen sense of smell. So a special perfume should be made there as well. ]
[Question] [ What will vegetation, weather and sea colour be like on a planet of an [F type star](https://en.wikipedia.org/wiki/F-type_main-sequence_star)? Assuming that the conditions are similar to Earth. (Enough ozone layer etc) The intelligent beings travelled there so they don't need a star with a longer life. [Answer] F type stars are very similar to G-type stars, except they are a bit brighter(irrelevant, the planet just orbits further out), and the spectrum is shifted up a bit. G-type stars emissions peak at about 450nm , whereas F-type stars peak at something like 400nm. So your "white" light from the F-type star will be a bit bluer. (actually just even more violet than our star G-type is). As you have stipulated thick enough ozone, this is almost completely irrelevant. The light that reaches the surface will be very, very similar. The visual appearance of the sun will be a light source similar in total power to our sun, but smaller, bluer and more intense. About the visual difference between a modern bright LED room light, and an older incandescent one of the same lumen output. Weather: the upper atmosphere will absorb a larger fraction of the solar output. Your ozone layer will be working overtime. This should have almost zero effect on ground level weather. The main difference between and F and G type star is that the F-type burns brighter, uses up its fuel in 1/5th of the time. 2-3 billion years, compared to the ~10 billion years a G-type gets. So life , if it develops under an F, had better get its act together and fast, or it will run out of sun before it figures out how to grow lungs. Earth life took longer than an F-type would provide, already. [Answer] It is close enough to Earth and Sol that it can be whatever your story requires. Tortoises and whelks, yes. > > What’s the good of a plan that ain’t no more trouble than that? It’s > as mild as goose-milk. Why, Huck, it wouldn’t make no more talk than > breaking into a soap factory. - [Tom Sawyer, from Adventures of Huckleberry Finn](https://etc.usf.edu/lit2go/21/the-adventures-of-huckleberry-finn/214/chapter-34/) > > > Tom has a point. Ho. Hum. Instead: Tidally locked chthonian planet! This hot jupiter has had its hydrogen and helium blown away from staring its Sun in the eye. What is left is the heavier gases and a water ocean: the Great Chthon! Plants are chemotrophs because it is too hot on the sunny side for life. Light on the dark side is reflected from the clouds and from its several phenomenally bright moons so the sky is dark. Energy for the plants is chemical energy, formed by the riot of reactions on the hot side - pretty much every kind of combination the atmospheric gases can make gets made under the blast of light. These molecules are then carried with the perpetual high winds of this planet to the dark side. Nearly everything is underwater because of the high winds. The different plants specialize in different chemicals - some reducing cyanide, some hydrogenating acetylene with water. All have in common large surface areas to maximize their ability to capture nutrition blowing in from the hot side. Some plants extend up above the water to gain an edge on their subsurface competetion and then lose these dispensable suprasurface appendages to the frequent storms - if not the wind, then the lightning. The farther you are from the terminator the larger these plants get because the currents get weaker as you approach the dark pole. T These plants are a riot of vivid colors to our eyes because of their protective compounds - herbivores are everywhere. Animal life feeds among the plants and there are fliers which avoid the larger water predators and cruise along looking for their favorite feed. These might perch on the plants which extend up out of the water. They can tell when a storm is coming and try to outrun it, or hunker down under the surface until trouble passes. Moonlight is bright on this world and there are 3 moons to provide it. On a moonless day the only natural colors are short frequencies that can scatter back from the sky - blue, indigo, violet and ultraviolet. Under the surface it gets dark fast and many creatures make their own light, like residents of our own deep seas - and for the same reasons: communication with their own kind, attraction of prey, defense from predation, camouflage against a relatively brighter sky. The bioluminescents come in all colors. Plant equivalents on the dark side make their own light to attract pollinators. To a human eye, the dark side is all blinking lights: Vegas from the air by night. But work out before you go because gravity is 4x Earth gravity, and wear your goggles because the wind is no joke. > > ...I knowed mighty well that whenever he got HIS plan ready it > wouldn’t have none of them objections to it. > > > And it didn’t. He told me what it was, and I see in a minute it was > worth fifteen of mine for style, and would make Jim just as free a man > as mine would, and maybe get us all killed besides. > > > [Adventures of Huckleberry Finn](https://etc.usf.edu/lit2go/21/the-adventures-of-huckleberry-finn/214/chapter-34/) [Answer] The sea color would appear about the same. The light output of the star would make everything look more whiter and brighter. Tropical sea may look sharper and more deeper turquoise, but it should be fairly the same. With increased solar output, more energy per square meter would be deposited to the ocean surfaces. This should increase the rate of water evaporation, thus more clouds and possibly more rain in areas, while the deserts will be more brutal. To keep an atmosphere longer term, it may have a thicker atmosphere. About vegetation, it took life around 1.5 billion years to develop land plant life more complex than slime mosses and algae. as @pcman stated, the stars average life cycle being 2-3 billion years, if you came to this world late in its life you may get more complex life. So, if you came there in the equivalent of the carboniferous period (which may not even exist due to not enough time to evolve), you will have basal trees, tall and lanky, all vying for light. With increased solar energy and higher UV output, the leaves may be larger, thicker and more leathery to survive damage from UV light. With higher energy output, it may not need to have as much chloroplast to get the energy it needs. Plus it could help reflect some harmful excess light energy being lighter in color. More than likely, your life would be restricted to the seas, being fairly simple forms of life as not enough time to evolve would be allotted on this world. More than likely, your world would be restricted to the development of no later than the early Paleoproterozoic period. <https://en.wikipedia.org/wiki/Paleoproterozoic> ]
[Question] [ This is set on a fictional alien world with medieval people. However, this world has alien livestock that are capable of flying into outer space and traveling to other worlds. These medieval-age people figured out how to use the animals to tow their ships from planet to planet, all with no technology. Would they be able to create a ship or ark that can withstand the elements of outer space using common materials? They would have protection against radiation and have their own source of water and heat and air and water using fictional means. However they would need to build their ships using common resources such as oil, tar, wood, etc. Is it possible to build a ship or ark out of wood and other common materials that won't implode in space? They would also have their own type of epoxy sealant that will make their ships absolutely airtight, which would also protect them and their ships from radiation, etc. [Answer] If airtightness is the only requirement, then yes, medieval people could create such vessels By middle ages, creating watertight ship hulls was a very common task. Yes, ships leaked, but that could be successfully mitigated. Also, diving bells were known since antiquity, and fully isolated "dry" bell is not very different from a spaceship. 1 atm pressure difference could be easily handled by wood and metal construction. Dealing with the coldness of space is more tricky, because iron will become brittle, and any wet insulation will become dry, but if medieval NASA can get enough tries, they can find out what works and what not. Radiation hazard can be mitigated by building thicker hulls. This is something that the builders absolutely can do, but they must know it from somewhere, or learn the hard way. Excessive G forces, atmospheric shocks, high temperatures and life support would probably be too much to handle for medieval technology, but that seems to be outside of scope of this question. [Answer] No. they can't make a airtight container big enough for weeks of travel, especially not one that can withstand vacuum. Even a day of travel is probably impossible. You need a shipping container worth of air per person per day. Since it needs to have doors it gets even less likely they can make it airtight. The only technology they had for making airtight containers either relied on glass, or barrels, which have a scaling limit. if the travel times was an hour or few they could maybe manage with large single use barrels, assuming they someone at the other end to let them out. But even then it is iffy, wooden barrels can't withstand much internal pressure. Even the materials themselves have problems. Wood, tar, pitch, glue, all these materials outgas in a vacuum, meaning they won't work for a seal in vacuum, natural material don't make great vacuum seals. if this is actually space, then uneven heating by the sun will cause even more deformation which is destructive ot seals. Material problems large barrels and ships are made in very similar ways at least in terms of making them watertight, tight fitting planks with either with nothing (rare) or a caulking (common) sealing joints. Usually cordage soaked in pitch or tar. All of which seriously outgas under vacuum, so they will break down or fail almost instantly when subjected to vacuum. Sealing things against vacuum is hard without modern materials because all traditional glues and sealers contain volatiles the boil off at vacuum pressures which destroys the material. If you want to get an idea of what happens put a marshmallow in a microwave. Even the water in the wood will boil off deteriorating any seals in contact with it and can even damage the wood itself. Mechanical problems Barrels work much better for our purposes because they are reinforced on the outside relying on compression to seal them so they can withstand some pressurization, but they still suffer the outgassing problem and the internal pressure they can withstand is still low, the end caps can't be braced like the sides so this is where leaks tend to start. Ships are pegged/bolted into place so will be far weaker to internal pressure, which makes sense they are designed to withstand great external pressure. ]
[Question] [ High power projectile weapons, often firing their rounds near the speed of light, are a staple of sci-fi. Under certain assumption sets these weapons are valid, I'm not interested in the science (or lack of) around how to build such a weapon, but I have wondered for a while about one particular aspect of such a weapon, detection. [This excellent answer](https://worldbuilding.stackexchange.com/a/131977/40408) indicates that any projectile travelling near the speed of light will be reduced to a cloud of plasma by its continuous impacts with the atoms and dust of the stellar medium very rapidly. At lower relativistic speeds you'll see the same effect just a bit slower. Even if we assume that the projectiles in question are travelling slow enough to make their designated trip they'll still shed some mass to, and be lit up by the energy from, molecular impacts during the trip to their target. The glowing plasma they'll be surrounded by will make them relatively easy to detect en route and possibly defend against in some way. Is there some material that a relativistic projectile could be sheathed in that would minimise this effect and allow such weapons to go unnoticed in transit for as long as possible? In answering this question ignore the larger impacts with dust and micro-meteors they're going to be both rare and due to their size unavoidably highly destructive. Concentrate on the effects of the [solar wind](https://en.wikipedia.org/wiki/Solar_wind) and it's mitigation, and projectile speeds of approximately 10% light speed. [Answer] The particles you will be impacting are of two types: charged and neutral. Providing the bullet with a magnetic field will deflect the charged particles and leave you only to impact the neutral particles. This will result in a lower fingerprint and a more difficult detection. [Answer] Install a powerful refrigerator in the projectile. Cold refrigerant coils cover the forward surface. The heat from molecular collisions is pumped from the front to the back, where it is radiated away. If the heat generation rate from collisions matches the rate at which heat is radiated away, the projectile won't reach excessive temperatures. The radiator should direct the heat away from anyone that might see it. Alternatively, or in addition, equip the projectile with an extremely powerful magnetic field sufficient to redirect incoming charged particles to the sides. Something like a [Bussard ramjet](https://en.wikipedia.org/wiki/Bussard_ramjet), except you want to push the particles away instead of funneling them to the center. All this equipment would increase the required mass of the projectile, but it's best for the projectile to have a small cross-section, to reduce the collisions. So the projectile would be shaped as a long and thin rod. [Answer] In addition to the already existing proposals of magnetic deflection and/or refrigeration, a much simpler cooling scheme can be used. Coolants (e.g. liquid helium, nitrogen or any other good evaporative coolant, depending on the requirement of surface temperature) can be directed to the "front" of the projectile, absorb heat and be ejected from the projectile. With adequate design, this cooling system requires very little moving parts and complex, expensive machineries. Of course the disadvantage is that the projectile gets lighter during the flight, which isn't a good idea for relativistic projectiles, but with cheaper projectiles you can always shoot more to compensate for the loss of kinetic energy. [Answer] ## They can't be stealthed. Each collision with a proton generates (1.6726219\10^-27 kilograms) 30000000^2= 1.5*10^-12 joules of energy. Assume a projectile of area 100cms, and 3 projectiles per cubic centimeter. Every thirty million meters of motion, every second they'll heat up 45 joules. [20 watts is enough to detect Voyager 1 from 18 billion kilometers away.](http://www.projectrho.com/public_html/rocket/spacewardetect.php#nostealth) It would be enough to detect your projectile, especially with futuristic space technology. ]
[Question] [ A side character, a sister of my main character, has been stricken with an unidentifiable disease in an early 19th century circa 1800 - 1850 setting. She's had the disease for a few years. Country doctors with little education but an intent to scam have done ample bloodletting, and given her chalky medicine that did not help. Later in the story when her father travels to a coastal city, a doctor informs him from information given that his daughter has tuberculosis. He recommends the girl come to the coast where there is "better air." From my cursory reading on the subject, what actually heals her is simply time and being outside, as she was shut up indoors for much of her sickness. So my big concerns - I am sure this is not being presented realistically, how can I do so? What hints can I drop for what this is? What views did people have on tuberculosis that would've been realistic for the time period (I'm considering the possibility that my world has an early understanding of germ theory at this time). [Answer] # To your question: Yes, that is quite in line with practices of that era, and can somewhat actually occur like that. Some facts about [Tuberculosis](https://en.wikipedia.org/wiki/Tuberculosis): (historical perspective. Modern treatment is a whole other field of complexity) * TB was known as "consumption". * It is an infection by the bacterium Mycobacterium tuberculosis * By the 1800's, consumption has been the cause of 1 in 7 deaths in all of history. * Without antibiotic treatment, it is almost impossible to actually defeat TB. It is possible for a sufferer to push the disease into remission, and be apparently healthy. However once you have had active TB, the disease is permanently in your lungs and just waiting for your immune system to weaken a bit, and let it back in. Only with a vigorous and highly targeted antibiotic regime can the disease be fully removed from a patient. In your scenario, this is what the patient achieves: a full remission, not an actual cure. * In Europe in the 1800's, as much as 25% of the population were in this state of TB remission!! * Better air, less pollution to irritate the lungs, and higher air pressure all ease the function of the lungs, allowing the body to spend a bit more strength on healing and fighting the disease, rather than just gasping for oxygen. Also, relocating from an indoors self-inflicted prison to a countryside setting will promote some healthy exercise. So yes, a "good air" relocation is advantageous. * Bloodletting can provide immediate partial symptomatic relief, it is speculated that the efficacy of bloodletting on TB (and malaria) is what caused its popularity as a traditional treatment. Unfortunately bloodletting also weakens the system on the longer term, and can easily be so overdone in the short term as to kill the patient. (not to mention the unsanitary methods of traditional bloodletting. Dirty knives! Leeches!! ) There are several other folk remedies that ease the immediate symptoms a bit and provide support, but do absolutely nothing to actually cure the disease. [Answer] Tuberculosis would have been recognized by anyone in that period. It was super common. Oslers medical textbook covered the entirety of medicine at the time and it devotes 80 pages to tuberculosis: 10% of the book. Here is some back reading for you: William Osler on tuberculosis, 1892. <https://archive.org/details/principlesandpr00mccrgoog/page/n252/mode/2up> I linked the part where he is talking about treatment. If you want to accurately depict a tubercular person of this period the whole 80 pages is gold. He has many anecdotes, minutae about hemoptysis and other things that are coughed up (pearls of calcium, which your girl could wash off and collect), fevers etc. When you get to treatment you will see details about the fresh air treatment as you intend for your character, as well as medical treatments like creosote and arsenic that you could have as the treatments early on. I think Oslers textbook is great. It is so accessible and well written, with clear descriptions of diseases and disease processes and detailed recommendations for treatment. It comes from a period shortly after when yours is set but that is OK. ]
[Question] [ I have an air breathing species that, for reasons of Plot, spend most of their time underwater. They’re pretty much comparable to humans in everything except how long they can hold their breath. Twenty minutes is the average. Only children and the disabled can hold it for less than five minutes. This particular race live in the submerged, upturned ruins of a past great civilisation. Various air pockets have formed in the ruins submerged in the shallow waters on the coasts of their world which they can use as shelter from the various nasties on the main land masses and also the things that lurk in the deep. These ruins are airtight and pretty much indestructible, so if left undisturbed the air pockets would last a long time. This race is smart, but pre-industrial, and the air in their homes is obviously finite. Any attempt to equalise the pressure with the surface using hoses etc will flood their homes, so the question is this: How can this race cycle bad air out of their homes and good air in, using pre-industrial tech I know some species of spider will capture bubbles of air from the surface and drag them down to their nests to keep a bubble of air for themselves. Could this be a viable tactic for much larger creatures? If the trip to the surface is short enough could the large lung capacity and low oxygen use of this species mean exhaling right after coming from the surface is good enough to refresh the air in their homes for a while? [Answer] Long term, big population - they cant without some kind of "ancient artifact" Short time solutions(for 100 maybe 500 years): * leather bags, size around seal, air goes in, stones to make buoyancy lower and You can replace some (100-200liter) air in house/room. Do that 50-100 times per person and You are good for a day(adult human needs around 10 000 - 11 000 litres 20% oxygen air per day). Can transport it in person or can construct something like reversed water wheel with bags instead of cups, work even up to 10m deep. * archimedes tube(screw) - can be used to pump some air down under water. Can be used for 2-3 meters deep, maybe 5m if have good and precise enough mechanics. Small population: * plants/fungis/bacteria or so. They generate oxygen slowly, big cave(room) can be replenished with oxygen in month or two. If cycle living in that rooms then can sustain some people [Answer] A Reverse Handpump Are you aware of what a handpump is? It's a small Mechanical device used to pump underground water up the surface using the concept of the vacuum. You can create something like a handpump, just the other way round that can be used to pump air from above to below. It is also important to note that it will help in keeping the pressure in your air bubble high if you make changes accordingly. [![handpump](https://i.stack.imgur.com/XsUx7.jpg)](https://i.stack.imgur.com/XsUx7.jpg) [Answer] For reasons of Plot air just bubbles up from underground. Maybe there's some chemical reaction going on down there, maybe it's being pumped down by the civilization who built the ruins, maybe theres some electrochemical process from powered by some still running nuclear plant. It is the mystery of the age: Alchemists have tried to replicate it, budding scientists try to understand it, but no-one knows where it comes from. The religeon mentions a time when the bubbles stopped for several days necessitating extraordianary effort to keep most of the population alive. The prophets warn that one day it will cease altogether, but for now, it is there, so the locals use it. In Rotorua (one of New Zealands geothermally active regions) it is not uncommon for houses to be heated by tapping steam that comes from underground. It's just "there" and is free energy so why not use it. In a similar way, your locals have discovered that there is air bubbling up from the seafloor in this one area, and the bubbles get caught by the ruins. As such, thry went "huh, looks like a safe place to hide." They moved there, got good at fishing and din't see a reason to leave. --- Air just bubling up solves many problems: * Buildings can leak, so long as they leak slow enough. * New buildings can be built, old ones can be repaired * It gives a reason for them living underwater at that location But yes, it is "magic" [Answer] From the way you described your scenario, the most simple and effective solution without requiring advanced technology would be a hose or a watertight stone tower that would function as a "air chimney" of sorts. From the way you describe your people its sounds like its possible for them to set up air bubbles next to a site of construction and build up from the ocean floor. You would start by making a stone foundation or by building on top of a solid surface on one of the ruins. You would build the tower to be a few meters higher than sea level at least, once the tower is finished you can "pump" water out from inside the building into the sea using a Siphon like this: [![enter image description here](https://i.stack.imgur.com/yBUcw.png)](https://i.stack.imgur.com/yBUcw.png) once build, the top of the tower could be manned, you could also have multiple backup towers that funnel air in and out of one or more large buildings on the ocean floor. This could create the need for a corps of volunteers/militia that would function like a sort of fire brigade, except their main duties would be manning operating and repairing the towers, and closing the towers manually using lids incase of unnaturally large waves/emergencies. Although I guess lids would require a sort of sealing agent if that is available. I hope you find any of this useful. ]
[Question] [ I’m currently working on a scene for a book where the heroes stumble across a seemingly abandoned Age of sail airship. After a brief investigation they find that the entire crew seems to have mysteriously dropped dead. How and why I am keeping close to the vest, but what I want to know is, if all the crew are dead, how long could such a ship remain airborne? I want to know weather or not the ship will be flying or crashed by the time my heroes stumble across it. [Answer] Rigid Airships require constant adjustment - ie. likely not very long at all (minutes only) Unfortunately, rigid airships ('Airships' implies rigid, which are motored and different from 'blimps') require constant operator input to stay afloat. This is because rigid airships can only have one 'buoyancy setting', the gas inside the gas bags are inflated, and lift is altered only by: * adjusting ballast * adjusting pitch of propellers * adjusting pitch and speed of airship as a function of wind over control surfaces Initial buoyancy settings are set to allow the airship to be controlled in normal flight and allow it to land (landing being one of the most dangerous requirements of airship flight). Unless the initial buoyancy setting is quite high, by the release of all ballast, the airship will succumb to either: * common downdrafts forcing the airship to lose altitude (faster than you may think, this was the cause of many airship crashes) * pitch adrift, causing loss of control and propellers to orient in a way that could cause the airship to pitch down * wind movement over incorrect control surface settings, causing pitch down and loss of altitude As they require constant adjustment, an estimate of time with a complete loss of control would mean the airship really only has minutes to survive, maximum perhaps an hour, unless all ballast is released suddenly, causing lift upwards. However even if this happened the airship is still susceptible to downdrafts or wind which can only be countered by pitch up propellers and elevators in normal flight, so in these events no control would still cause an imminent crash and loss of the airship. [Answer] It seriously depends on the airship. For example some ~~airships~~ blimps can stay up for as little as 24 hours. Some may stay up for a few days to a week. Basically until the lifting gas escapes, which depends on the gas. But lets assume the lifting gas does not escape, then until the first storm comes and breaks the airship, since they are quite fragile (Most airship disasters were because of this. Such as the USS Shenandoah) But if it was made with age of sail manufacturing, I'd give it a week at most, since the would gas to escape, but certainly not over a hundred, since the fabric of the shell would rot assuming the airship magically avoided all storms. [Answer] # Absolute maximum: half a day The buoyancy of an airship changed constantly from many factors, but the greatest of these is the simple thermal heating of the gas from sunlight warming. Both direct (on the surface of the blimp) and via atmosphere heating in the daylight. As the air around the blimp warm or cools, and as the gas in the blimp warms and cools at different rates, the buoyancy of the blimp gets upset. Unattended, it will either sink down until it hits the unforgiving surface of the Earth, or worse it will rise up unchecked until it hits the even less forgiving limit of altitude where the pressure safety valves of the gas bladders are forced to vent gas to prevent rupturing. Once vented, and especially with no crew to replenish (if there even is a way to replenish, which is very uncommon!!) the airship will start descending very rapidly, and is due for another meeting with the hard surface of the Earth. Some blimps, and all dirigible airships like Zeppelins, controlled their altitude dynamically, by literally "flying" up or down using control surfaces. They could also drop ballast to lighten themselves, or vent gas to make themselves heavier, but these were undesirable as they consumed very limited resources, whereas steering via control surfaces just required a tiny amount of fuel to keep the dirigible moving to enable the control surfaces. [Answer] Like the ocean, the atmosphere can have temperature and density layering. If it happens that the ship's buoyancy was trimmed correctly to float on a denser air layer (cold air trapped in a valley or canyon, for instance) the ship might remain aloft until leakage of the lifting gas brings it down. Alternatively, if the ship happens to be trimmed "light" when control is lost (or close to neutral with engines running, which will make the ship light as fuel burns off), it will climb, ultimately to "pressure altitude" where the gas in the lift cells cannot expand further (because of limited space or elasticity in the cell material); if the cells are strong enough, an airship might remain at that altitude (much too high for crew survival without oxygen) until, once again, lifting gas leakage brings it down. In fact, if control of the gas vents was lost, this might be what killed the crew -- a combination of hypoxia and hypothermia as the ship ascends uncontrollably to the tropopause. [Answer] Mysterious boy. Aside from the ships cat, there is a survivor on this age of sail airship - a boy. He is a foreigner of some sort - and a deaf mute and possibly a simpleton. But he has kept the boilers fired on the ship and kept other things running. He cannot steer the ship or land it and he does not know how to signal for help, but he knows enough to keep the ship aloft and he knows he does not want to crash. He has covered the bodies of the dead with sails but otherwise left them alone. He probably saw what happened. Or so one would think. The cat will have nothing to do with this boy. ]
[Question] [ The fossorial people are small humanoids. They have hair on their head, but it only grows to around shoulder length. They also have similar hair on their chest, hands, and feet. This hair can resist dirt. Their skeletal characteristics are described [here](https://worldbuilding.stackexchange.com/questions/205889/what-weapons-would-fossorial-people-use). What clothing would be best at resisting dirt while crawling through or digging dirt-tunnels, while still keeping the wearer warm in an environment akin to medieval Britain? [Answer] Why Wear Clothing at All? Consider normal nudity. If these people evolved to live underground, then they've probably grown accustomed to dirt, insects and the like. Clothing is a matter of culture more than anything else, and seeing as humanoids (bigger ones) have historically gotten along just fine & naked (Tierra del Fuego), there's no obvious reason why these people must wear clothing. Apart from difficulty in obtaining materials, in the darkness, clothing won't be useful for signalling or decoration (since it's so dark) and anyway, everyone will just misplace their socks. It's easier to go without! [Answer] The only fibers, or fiber like structures, which they can access underground are roots. The roots of adequate diameter can be dried and woven together to produce a very rough fabric, at most resembling yuta bags, which can offer some protection against contact with the underground. This is what they probably actually need, since a few meters underground temperature is pretty much constant all year long with very small fluctuations when compared to the changes above ground. ]
[Question] [ What could exist buried in the earth that is sugary and can be used to sweeten food? It should be relatively common, and at a depth where it is only accessible to peoples specialized for digging (specifically, the people described in [this question](https://worldbuilding.stackexchange.com/questions/205889/what-weapons-would-fossorial-people-use)). Also, the sweet thing should be something that might have come to be on Earth [Answer] Manna (but not from above). During the wintertime, tree-sap sinks beneath the ground into the taproots of the trees (the ones that sprout from the main side-roots and then go straight downwards). These are only accessible beneath the canopy of the surface roots, and a dig must start some distance from the tree-trunk and then curve inwards underground. The Ash tree (AKA. spruce, or fraxinus) produces in the summer, a sweet, protein and mineral rich sap, which during winter months can be drained from below. Cutting the tip off a tap-root, will enable several liters (from a medium/large tree) to be drained without killing the tree itself as the many other tap roots are enough to get the thing sprouting properly in spring. There's even one gentleman [who does it for a living](https://www.atlasobscura.com/articles/where-is-manna-from) and to keep an ancient tradition alive (admittedly he takes it during the sap-up months, from the trunk though). [Answer] ### Lead Aside from being toxic, lead is also very sweet to the taste. [It has historically been used as a sweetener](https://www.smithsonianmag.com/arts-culture/sugar-of-lead-a-deadly-sweetener-89984487/) with predictable consequences. Lead on it's own is naturally occuring and sweet, but with a little bit of simple chemistry lead acetate can be made, which is a sweet salt soluble in water and glycerin. Ideal for sweetening desserts and wines. [Answer] A lot of tubers grow underground, and some need some digging to be reached, like [yam](https://en.wikipedia.org/wiki/Yam_(vegetable)#Harvesting) > > Yams in West Africa are typically harvested by hand using sticks, spades, or diggers. Wood-based tools are preferred to metallic tools as they are less likely to damage the fragile tubers; however, wood tools need frequent replacement. Yam harvesting is labor-intensive and physically demanding. Tuber harvesting involves standing, bending, squatting, and sometimes sitting on the ground depending on the size of mound, size of tuber, or depth of tuber penetration. Care must be taken to avoid damage to the tuber, because damaged tubers do not store well and spoil rapidly. Some farmers use staking and mixed cropping, a practice that complicates harvesting in some cases. > > > In forested areas, tubers grow in areas where other tree roots are present. Harvesting the tuber then involves the additional step of freeing them from other roots. This often causes tuber damage. > > > Generally speaking tubers are rich in carbohydrates, because they are the energy storage of the plant producing them, therefore in principle all of them are either sweet or have the potential to be sweet. Something like a sweet potato. So, you are looking for something which is an interbreed of a sweet potato for the sweetness and yam for the challenging harvest. [Answer] If you want the ultimate sugar rush then maybe grow sugar beet [wikipedia link](https://en.wikipedia.org/wiki/Sugar_beet). 20% sugar. [Answer] Honey from ground bees. It's harvested by humans already ]
[Question] [ Broadly speaking, a [dry suit](https://en.wikipedia.org/wiki/Dry_suit) is a garment which restricts fluid exchange between the portion of the body covered and the outside environment. These work for humans because it is not unreasonably difficult to achieve a water-resistant seal between the suit material and human skin. (Yes, there are also varieties which completely surround the wearer, but for my purposes I am not interested in that method.) Alas, people in my world have fur. They still want dry suits; both for the reasons humans would, and also for other purposes, e.g. the ability to go swimming while needing to protect limited parts of the body from water (e.g. due to injuries or... [other reasons](https://en.wikipedia.org/wiki/Kink_(sexuality)), and because this is a harder problem then creating a fully-enclosed suit). Rules: * The garment must not require the user to shave; my people's vanity will not stand for such an offense (and it would be very inconvenient). * Putting on the garment should be relatively easy. Having to part fur to get a good seal is fine. Having to put special goop in one's fur (as long as it will washes out again!) is less desirably, but not categorically unacceptable. * The garment should restrict ingress to 100 mL or less given a "seam" length of 1 m (e.g. around the waist) and an expected 4-5 hours of use. * The above only needs to be accomplished to a maximum depth of 5m. (However, if it won't work up to at least 15m, please show why. I'm more interested in swimming pools than deep diving, though.) * Gravity, pressure, etc. are approximately Earth-normal (close enough to make little difference, anyway). For the purposes of this question, something that would work on a roughly-human-sized animal on Earth is acceptable. Is a dry suit — or, more generally, a water-resistant seal between a garment and the wearer's fur-covered body — still possible, strictly according to science? If "no", but if I also have magic that can continuously repel water with a force of 10 N, does that help? [Answer] Vaseline Your creature's vanity be damned, your only option other than shaving is to use a gel such as Vaseline to create a gasket the suit can bond to. The seals will still need to be tight and you will always have a pressure limitation that's less than what could be achieved with skin alone — but it would work. The gel would need to be worked into the fur such that it coated the fur to the skin and was wider than the seal band on both the inside and the outside. Then add a vacuum On top of this, design the seals to produce a vacuum. It need not be electrical. A lever (not unlike those found on suction cups) would be enough. Removing the oxygen within the seal would improve the quality of the seal (like suction cups). If you adopt this aspect, the seals would need to be flexible enough to form to the shape of the body. [Answer] ## The same way as thinly haired humans do. (Assuming of course that when you say 'furred' you mean a normal layer of fur as per the average animal not thick fur like that of a yak, polar bear or lions mane etc.) Just use slightly longer and (more importantly) tighter neoprene, silicon or latex seals where needed as well as a thick layer of Vaseline rubbed into the fur under the seals. And go with one piece dry suits and one piece neoprene undergarments. Between the undergarment and the fur your characters should stay warmer and dryer than normal divers because all fur is slightly water resistant and provides an extra layer of insulation via the air it traps. But remember normal dry suits do leak at least a little because the water tight seals are never perfect. ]
[Question] [ [Demons](https://worldbuilding.stackexchange.com/questions/206633/could-these-demons-exist) live deep in the underworld. The underworld is a strange place: It is a cave system, composed mainly many extremely large caverns, with a few wide corridors connecting them. The ground of these caves is unusually soft and loamy, and has many relatively wide streams cutting through it. There are no trees, but instead the only plants are climbers, which stick to the high walls of the caverns, with the roots at the margins of the soil. There is also a clade of mosses, and several types of lichens. These plants feed on the radiation of the cavern walls. There are also many types of fungi and animals, including many domesticable animals with large bones, tusks, and other hard parts While the demons have no shortage of stone, it is still expensive, and would not be suitable for vehicles, and various other things. There are also metals, which could be used in wagons and other such constructions, but are still generally quite dense, and it seems like they would generally be better used for weapons and other such things. Furthermore, neither stone nor metal are useful fuels Out of all the materials that might be found in the underworld, what could replace wood, specifically in the realms of fuel, building construction, and things like vehicles and furniture? [Answer] > > Replace wood (...) in the realms of fuel, building construction, and things like vehicles and furniture? > > > # Animals > > fuel > > > You could breed animals into varieties that produce blubber. That is a nice fuel. The biggest point of the whaling industry by the 1800's to 1900's was harvesting whale oil, which burns without making smoke - great for a cave system. > > building construction > > > Vertebrate animals have bones[citation needed], and sometimes leather, which your demons could use to craft stuff and build buildings. > > and things like vehicles > > > Horses were THE land vehicle for humans for more than 90% of our history. Saddled models were the most popular, but in most times and places you would also find makes that came with carts attached. Some vehicles included multiple horses attached to the same carriage for extra HP. > > and furniture > > > See the part about building constructions. If you can make a cot out of it, you can make a chair out of it. On top of that, feathers, wool and silk are great for making cushions and beddings. [Answer] All kinds of scavenged stuff. [![portal](https://i.stack.imgur.com/mpNas.jpg)](https://i.stack.imgur.com/mpNas.jpg) <https://forgottenrealms.fandom.com/wiki/Portal> The underworld has portals. And it is lucky for its residents that it does because otherwise the air would be stagnant and things that breathe would suffocate. Certain of these portals produce high winds, either in or out - sometimes steadily and sometimes this will vary unpredictably. All of the portals lead to other places. Portals offer access to these other places for the demons. This can be risky; a portal can shut, or can lead to a dangerous place. The portals are not all consistent. Some portals are pretty predictable and offer the demons opportunity to gather raw materials or scavenge / steal finished goods. The demons thus have a hodgepodge of materials and items depending on portals, availability and bravery / luck of individual demons. [Answer] Some additional possibilities to add to The Square-Cube Law's fine answer: Fuel Organic matter akin to peat could accumulate, which could be harvested and burned. You could have types of lichen or algae that produces hydrogen or methane as part of it's metabolism, which are cultivated in catchments. And of course the vines could be burned directly. Construction A number of earthen construction forms could be made to work and be easier than dealing with rock. Perhaps your loamy soil hardens when fired, or when mixed with a cement analogue that can be mined in the caves. Furniture See above. Also ropes made of vines or leather can be used for hanging furniture, ]
[Question] [ I've got a creature here. Generally around 4 feet tall. The head is not as tall as a human head, but wider, so the brain size should be the same. It has a wide snout with crushing predator teeth like hyenas, so this head is heavier than a human's. Has a nuchal crest. Approximate head size compared to human from front[![Front](https://i.stack.imgur.com/urLGA.jpg)](https://i.stack.imgur.com/urLGA.jpg) Side view[![Side view](https://i.stack.imgur.com/lLVvi.jpg)](https://i.stack.imgur.com/lLVvi.jpg) I've already given it some spinous processes on the neck and back. It has digitigrade feet. It can change from upright to quadruped stance, so I've given it thick legs to give it some balance weight on the back end. Front facing cross section of chest; also shows neck width [![Chest](https://i.stack.imgur.com/7Ey1p.jpg)](https://i.stack.imgur.com/7Ey1p.jpg) Is that enough spinous processes supporting it? If not, how much spinous processes; muscling and tendons (and cervical ribs if needed) does it need? Or is it more than necessary? If possible I'd like to not have more of a back hump than it already has. How flexible would the neck be with these supports? Is there enough weight at the back to not fall forward during quadruped movement? Any other needed changes? Version with nuchal ligament and longer forwarded neck[![version nuchal](https://i.stack.imgur.com/6Lof3.jpg)](https://i.stack.imgur.com/6Lof3.jpg) Version 2 with nuchal ligament[![NL v2](https://i.stack.imgur.com/dKmx9.jpg)](https://i.stack.imgur.com/dKmx9.jpg) [Answer] Give them a dog neck. Dogs are able to maintain their head up due to their nuchal ligament. That would keep your creature comfortable when quadrupeding. A dog neck is also flexible enough to rotate forward when they are standing on two feet. Notice that due to this ligament, keeping the head up is actually the neutral, resting position for dogs. They have to make an effort to lower their head - analogous to how we need to make an effort to flex out feet (in our feet case it is a tendon that keeps the neutral position, though). Other quadruped mammals have similar arrangements - AFAIK horses have a nucha ligament as well). ![Anatomy of a dog neck, showing the nuchal ligament](https://i.stack.imgur.com/6pg4Z.jpg) [Answer] with a neck that thick, it should be fine. That said, you may want to give it a hump on it's back and shoulders to attach extremely powerful muscles. Many large animals with large heads have elongated spines above their shoulders to support powerful neck muscles. Bison are a good example. [Answer] Very strong neck muscles and bones can do the trick. This will probably result is a visible "hump" between the shoulders, where the neck muscles are more developed. Something akin to the hump of bulls and bisons, with very pronounced spinous processes, to ensure the muscles have enough attaching points. ]
[Question] [ In most animals there is a different way of producing gametes: the male produces them "on demand" at the time of the reproductive act, while the female produces them on a roughly "fixed schedule", no matter if that coincides with a reproductive act or not. For my fictional humanoid species I want to have both male and female sex being capable of producing the gametes "on demand", while still being viviparous. Is there a way for explaining this without using magic or handwvavium? [Answer] A popular theory of menstruation is that it's [an evolutionary adaption to predatory fetuses](http://www.bbc.com/earth/story/20150420-why-do-women-have-periods) as some fetuses take too much blood and risk weakening the mother, and menstruation serves as a way to kill hostile fetuses or damaged ones that are a waste of resources. You can just have the mother be fertile all the time, and always have eggs available, just that means bad fetuses will be able to grow more effectively, either weakening the mother or self aborting when they fail. This is risky for long pregnancies needed to make intelligent beings with powerful brains. Your humanoid species might have adapted by having smaller babies that are less smart but physically adapt. This would make regular and quick pregnancy more feasible, as you could just dump lots of babies in the wild and hope for the best. [Answer] ## Induced ovulation What you want is called [induced ovulation](https://en.wikipedia.org/wiki/Induced_ovulation_(animals)) and it is quite common in the animal kingdom with a large range of triggers. Cyclic/spontaneous production like that used by humans is favored by social species (where males are present in numbers all year round thus encouraging competition) but many social species instead have only induced ovulation instead and even species with both are common. There is no reason a fictional species could not have it. [Answer] Age and making your own It is certainly possible. The egg cells in the ovaries are formed at a certain time. For males this is different, as we cannot store enough sperm to last through the sexual mature years. Most would run dry in a week. Two and two together show that there is a formation period and that on demand production exists, thus is viable. We can double check this by looking at the formation period. A woman only needs to form one, albeit more specialised, egg cell in about a month. A man needs to create thousands of them in days. Due to the longer time, a woman can use this to create a single more specialised one. The reasons can be a multitude, but most likely it's age. Currently people that are well off both get older, as well as get children when they're older. With menopause this means that at a certain moment you're getting closer to an undetermined time where you lose the ability to get kids. Strangely enough woman still have a lot of eggs left at this stage. If the humanoids had problems with getting kids on time due to the biological limits, it could have started an evolutionary pressure to generate egg cells on demand instead of storing them for life. As far as I can see there is no reason not to generate on demand. There might be more complications, as the amount of created egg cells per cycle might accidentally exceed the normal amount, resulting in a multitude of kids for example. But otherwise it doesn't seem strange to have generation on demand, allowing immortal females to have children whenever in their lives. ]
[Question] [ The fossorial people are similar to humans. They are around 3ft tall as adults. Their limbs are far stronger, and their hands and feet are larger, with the fingers being shorter and more robust, and the fingernails being like claws. In addition to standing upright, they are also good at crawling and digging with their hands. They live in burrows, which are composed of rooms large enough to stand in and use, and tunnels that must be crawled through. They have access to medievel-europe-level technology, and are rarely involved in war. They mostly have to defend against eachother, but occasionally have to deal with badgers invading their burrows. What weapons would be the most useful to them in defending themselves? [Answer] Small, large strong hands, strong arms. Burrowing. Outside: Spears. But if they have any choice whatsoever, they will fight in their tunnels, where hand-axes will be King. Note not hafted axes, if their tunnels are low enough for a 3-ft creature to need to crawl prone, there literally is no room to swing an axe. Hands that are both larger, but with shorter fingers, will have great strength but impaired fine manipulation. No fancy knife tricks for your people! But with their superb arm and hand strength, they will use hand-axes for attack, and a mix of hand-axes, spears and shields for defense. (you try getting past a defender in a tunnel, who is blocking the tunnel with a round shield, a spear poking past the shield, and a viciously swung hand-axe if you poke anything past the shield. I do not see personal armor playing any role at all. The loss of flexibility and mobility is simply to great, and the shield-in-tunnel too effective. I also do not expect ranged weapons of any sort to be useful, even outdoors. Short limbs and low profiles will make most missile weapons ineffectual, and I strongly suspect that a burrowing, underground-living species will not have the best longrange outdoor vision ability. [Answer] The Ixwa The Ixwa is the short "Zulu spear" a 2ft haft with a wide, 1ft long blade. For tunnel fighting in places so narrow and cramped a 3ft tall person might be required to crawl in places it seems like an excellent weapon. The long blade can be used primarily for thrusting, while providing a fair amount of metal which should make it harder for your opponent to grab past the point and break it off/wrestle it away from you. The shaft still gives you some reach, without being so long as to be awkward to maneuver. around corners. Of course the Ixwa was designed for people, so your Fossorials might use a somewhat scaled-down version. Perhaps a 6-8" long blade with a haft 2x the length. The Ixwa was designed as a one-handed weapon, leaving the other hand free for your shield. A Fossorial warrior may have a small shield (big enough to be useful, small enough not to encumber them in a tight spot) or may need the other hand to carry a light-source. Not sure. It could theoretically be used two-handed but that's more a slashing technique unsuited for tunnel-fighting. My guess (if they can reliably see in the tunnels) would be a preference for shields. For surface fighting the answer is probably culturally-driven. The Zulu Ixwa was the standard close combat weapon, backed with javlins for ranged attacks, and they lived in the wide open spaces. So if your Fossorials are fighting each other 99% of the time that's probably how they'll do it. Lord knows a Ixwa would work against badgers above and below ground! The loadout is known to be efficient, and there's no reason to force your warriors to carry/train with two completely different weapon sets unless you absolutely have to! If they ended up fighting humans best bet is they stick with Ixwa and javlins and either prove such a nuisance the humans back off and learn to live and let live or they're quickly subdued. Either way way I doubt they'd stray away from "traditional" Fossian weapons. If the humans are driven off, why change? If they're overrun, it'll probably happen to quickly to develop human-specific counter-weapons. They might possibly develop something akin to a pike, but that would really only match a human spear in length. So not super useful. Poison weapons may well feature vs bigger foes though, even if they're not used against other Fossorials. The book War Before Civilization has a great section on how human tribal warfare uses poison. Sparknotes version is, against people "similar" to the tribesmen (say two different tribes of X culture people) poisoned weapons aren't used. But the second X culture fight Y peoples everything gets a poisoned/tainted blade. Such tactics would be your little guys' only hope against the Big People. [Answer] Pickelhaube. [![kaiser with pointed helmet](https://i.stack.imgur.com/UYHrK.jpg)](https://i.stack.imgur.com/UYHrK.jpg) <https://www.historynet.com/the-purpose-of-the-pickelhaube-helmet.htm> Seriously! Consider these folks. They are crawling on all 4s. If they are humans that means their face is probably down. They are meeting enemies with the crowns of their heads. The pickelhaube is best against animals, because the fossorial human version extends down to cover the neck and shoulders, and has additional spikes down the back allowing the wearer to duck head and ram offensively. This leverages all 4 strong limbs of the attacker and does not present a vulnerable target to a bite or weapon of any sort. The other thing they would use are gloves with metal claws. Most fights in the tunnels are at close quarters and turn into grappling and claw work, both with foreclaws as well as a grip and hold then a catlike strike bringing forward the rear claws. Augmenting the natural claws makes sense. In addition, robust metal fortified claws on hands (and feet) offer better traction. When fighting on the surface these are the tactics the Fossorians use as well - a low scuttling charge with the pickelhaube forward, followed by grappling and claw work. It is a terrifying thing for upright tall folks. Once one of these guys has a hold of you and the rear claws go to work you are going to lose whatever you have in front. ]
[Question] [ In Space Engineers, Hydrogen is employed as a fuel for both propulsion and for electrical power (via the Hydrogen Thruster and Hydrogen Engine, respectively). This feels unrealistic to me, and I am considering creating a mod for the game that alters these pathways to more accurately represent real-world chemistry and physics. Therefore, I'm curious if this is a simplification for the purposes of game development/balance, or if there are valid, viable means to extract work from a feedstock of pure H2. The behavior is thus: * Thrust - Thrusters consume small amounts of Hydrogen while idle, and then much more to generate thrust. No other input to the system is required (not even electrical power, though because of the below scheme, it could be assumed that the same thing is being done here to generate power). The consumption of H2 is luminescent and sufficient to cause damage if one is close enough to, and inline with, the exhaust nozzle so I assume this isn't simply venting pressurized gas to space. * Electrical Power - Hydrogen is consumed to produce electrical power, the hydrogen engine itself looks like a reciprocating internal-combustion engine, which is obviously not the modeled behavior (that would require oxygen), but is there any legitimate hydrogen-only pathway? Hydrogen itself can be extracted from ice using 10% of the energy that the resultant hydrogen yields in this engine. Assuming I'm correct that neither of these make any real, physical sense, what is the highest mass-efficient pathway for production of power in both forms, using any (or any combination) of the following available materials either as reactants or catalysts? 1. Oxygen 2. Iron 3. Cobalt 4. Silicon 5. Nickel 6. Magnesium 7. Silver 8. Gold 9. Platinum 10. Uranium 11. Gravel (waste rock, let me know what common material you're assuming this to represent for your purposes) 12. Electricity 13. Heat [Answer] Long ago (in the 1950s), Robert A. Heinlein used "single-H" -- stabilized monatomic hydrogen (usually stored as a liquid, presumable at cryogenic temperatures though this was never mentioned) in a number of his novels and stories set in the same universe as The Moon is a Harsh Mistress, The Rolling Stones, etc. He used it mainly because it was the ultimate reaction mass for a fission thermal rocket -- the lightest possible exhaust particle and no energy sink for dissociation, hence highest possible exhaust velocity -- as well as (he posited) being capable of catalyzed recombination to work as a "chemical" monopropellant for attitude thrusters and the like. Obviously, this latter could also spin a generator via a turbine, or provide energy for a heat engine to drive a generator to produce electrical energy. Single-H would also make a good input for a catalyzed fusion system, in that there would again be no need to provide the activation energy to dissociate the molecules before they can be fused -- and catalyzed P-P fusion would produce enough neutron flux to make being too close to the reactor quite hazardous (not to mention being very bad for materials, but games often don't cover such details). "Burning" hydrogen by fusion is a long-standing shorthand from SF in any case, going back at least to Larry Niven's Known Space stories starting in the 1960s. [Answer] Hydrogen ion fusion. This accounts for the glow. Radiation! Your engine generates power thru hydrogen fusion. That is not particularly exotic sci fi. <https://en.wikipedia.org/wiki/Fusion_power#Deuterium,_tritium> Hydrogen ion thruster. Nothing too edgy here either. <https://en.wikipedia.org/wiki/Ion_thruster> Your fusion engine likes the heavy hydrogen isotopes which leaves you with 99% of the regular hydrogen. Bust it into ions, magnetically accelerate them to 0.9c using your energy, and huck it out the back! Woo! Zoom! [Answer] Oxigen (...) what is the highest mass-efficient pathway for production of power in both forms, using any (or any combination) of the following available materials either as reactants or catalysts? Oxigen is used both for burning and generating electricity. In both ways the hydrogen combines with the Oxigen and is able to release an electron because of the bond. Although the result is the same, water, the way it's done releases the energy differently. Oxigen is the lightest of the bunch that Hydrogen can combine with, so it makes most sense in mass to energy ratio. With the burning you obviously need heat as a "catalyst". ]
[Question] [ A inter galactic civilization is at war with a less advanced civilization, but one with a highly unusual number of super individual. Not only was the invasion of their system unsuccessful, but soon after an infiltration unit managed to steal several ships and FTL technology. The galactic civilization is now reorganizing its security to prevent a second breach based on the last successful breach: they know they have to defend against 3 types of super-powered infiltrators. 1. Psychics. Capable of causing hallucinations that make whoever sees/hear them (or someone accompanying them) perceive them as someone who belongs where ever they are. The effects works through cameras but has a limited range of around a mile. (Give or take a little bit depending on the power of the psychic.) This doesn't work on non sentient creatures. Also able to read minds. 2. Shape shifters: Capable of changing their shape and DNA, unable to change their mass. 3. Illusionists: capable of manipulating light to make illusions or turn things invisible. What measure could an advanced civilization take to prevent more infiltrations? [Answer] It looks like your security forces need to implement some basic Master/Stranger protocols which are designed to prevent security breaches from exactly these sorts of infiltrators. It should be noted however, that no individual security measure solves all your problems. Any proper security system involves multiple redundeant layered defenses to provide different levels of "trust". Here are some suggestions: * Normalize bio-recognition systems. Every time you board a starship, station, or even go though a security door, you've got to go through some scanner(s) that could check your iris, fingerprint, body shape, bone density, etc. These scanners are completely automated and while DNA-replicating shapeshifters can maybe fool them, this makes it more difficult for the psychics and illusionists (also, fingerprints are not a function of DNA! A shapeshifter would need to actually lift the target's fingerprints off a surface and use that pattern to guide their shape-shifting/make a prosthetic fingertip.) * Implement habit/person recognition AI via cameras. Instead of searching for things like fingerprints or facial scans, create an AI that identifies people by their habits. For example, gait recognition is already in use today and is both extremely easy to track and basically impossible to use to imitate someone else. Even an exact DNA shapeshifter probably wouldn't learn to walk the way the person they're imitating walks exactly. To do so, they'd need to copy someone's deep muscle memory, which I can imagine would be difficult for a psychic. * Basic anti-invisibility sensors. Dealing with invisible infiltrators isn't too difficult. Simply make sure that all critical doors and access ways are always "airlocks" that is a system of doors where two can't be open at the same time. Even better, make the airlock so small that only one person can physically fit into the space at a time so that invisibility infiltrators can't sneak in alongside someone authorized. Additionally, you can use sensors that don't rely on visible light like IR cameras to pick up thermal signatures or pressure plates to pick up the mass people stepping on them. * The tank. If someone is suspected of being an infiltrator, they need to go into solitary lockup for 24-72 hours. All workers in security critical environments are taught this, and maybe even paid overtime for time that they spend in "the tank". This encourages people to be suspicious and report other people without creating an overtly hostile environment. While the people suspected of being an infiltrator are in the tank, they go through a variety of personality tests and are under close observation by specialists. Unbeknownst to the specialists who are doing the observing, they are also under watch by remote specialists so that if a psychic who's in the tank attempts to mind-magic the observers behind the mirrored glass, the remote observers notice. * Passwords, passwords, passwords. Anyone working in a security critical area is going to need to become good at remembering access codes and challenge-response codes that change often. These can be used whenever by whomever, for example, if specialist Jane says, "Security code Omega-four-seventeen-november-rabbit" and her coworker doesn't immediately reply with "Zulu-five-hotel-hotel-niner" (or whatever the proper daily code is), then Jane is authorized and obligated to immediately subdue the coworker and put them into the tank for screening. Note that these codes are changed often so that even if a psychic infiltrator gains access to someone, the codes they gain would only work for a short time if they're not already expired. * Compartmentalization. This is already a standard procedure used for sensitive information here on Earth today. Essentially, it means that nobody knows everything. Information is "need-to-know" and even if someone is completely compromised by a shapeshifter/psychic, then the amount of damage they can do with that information is limited. People who, by necessity, need to know a lot would be placed under more extreme security procedures and protocols. * Anti-psychic measures. Even if there are no technological countermeasures against psychic powers, I assume it would be possible to train oneself to become resistant to hallucinations/mind magic. Even for grunts it should be easy enough to train them to press an emergency signal button if they think they're under the effect of some sort of mental effect. Similarly, memory manipulating drugs could be used to prevent mind reading. Scientists who retire might be forced to take an amnesia drug that wipes out details of what they worked on or more esoteric techniques like hypnosis could be used to render people incapable of remembering things they shouldn't. [Answer] Robots. [![robot](https://i.stack.imgur.com/u23xE.jpg)](https://i.stack.imgur.com/u23xE.jpg) <https://www.tintoyarcade.com/mini-radiocon-robot.html> 1. Psychics can't mess with them. 2. Shapeshifters cant fool them. The shape is all visual but robots rely less on sight and more on other senses, like body composition as measured by electrical conductance and mass as measured by muon backscatter. 3. #2 applies to illusionists as well. Apparent objects which do not displace gas on moving will immediately be recognized as such. Objects with no mass are no objects. If you robots are all the sexy type and are occupied making liquor ads, you could use trained dogs for #2 and #3 as well. Dogs will sniff out the truth. Psychics can mess with dogs a little bit which could be good for your story. Best would be a team of 2 types of your supers working together to get past dogs and robots. But not cyborg dogs! ]
[Question] [ A commando expedition is sent to country A. The fact that they come from country B must not be known in case they are caught in country A. In order to do so, they need to have a portable way to turn the body and equipment of a fallen soldier into something that would not be recognizable (dust for instance, but anything reasonable goes). How can they solve this problem? This is our contemporary world with contemporary technical capacities (plus some more because this is a powerful country with advanced research). This needs to stay within the realms of "can happen", so no magic or XXX century technology, but Iron Man-like solutions are probably fine. I hope that the `science-based` tag reflects this, otherwise please correct the tag to something more suitable. EDIT: to clarify, the context is not a documentary but fiction, so we assume a commando with high-tech infiltrated over a short period of time into country A (parachute, submarine, ...), that would have distinguishable gear (not an AK-47 but rather an advance rifle, latest+ technology suits, ...). They would clearly not be locals - thus the need to destroy all evidence. [Answer] I think it's part of the preliminary courses in counterintelligence that, whenever operatives are infiltrating an enemy country, they have to be equipped with locally available equipment: it makes easier for them to find local replacement or barter them in case of need and it's also easier to dismiss any claim that the operatives belong to the attacker, should they be intercepted. Can you imagine an infiltrated agent driving a Corvette in USSR during the cold war? This would mean also for the operatives to wear local clothes and obviously no badges/identifiers, unless they are counterfeited ones, again from a local organization. You are then left with the actual bodies of the operatives and any special equipment which cannot be disguised as local and that is really needed. For the bodies, a corpse cannot tell its nationality, and again picking operatives which are homogeneous to the local people would help in this direction: don't send a Michael Jordan alike for an infiltration in Yakuzia, rather someone with Asian like appearance. Just ensure that they have the means to commit suicide if needed. For the special equipment, you can have it either taken away from the other operatives, or you can embed an explosive charge into them to ensure you destroy the sensitive parts, and have it activated on demand. Generally speaking in a situation where the operatives are facing the threat of being captured with no means of escape you want something quick, so a suicide pill and some explosive are the quickest way to clean as much as possible. Completely destroying a body takes time. [Answer] Quilted body-bags. Well, how's that going to help? I hear you ask. Instead of downy feathers or hollow-fiber stuffing in the quilts, you'd use Iron oxide - aluminium based [thermite](https://en.wikipedia.org/wiki/Thermite#Types). It burns hot, very hot, around 2500 Celsius (4532 Fahrenheit) if evenly mixed, it's almost impossible to put-out once it's started burning, it'll melt steel weapons and render to char any electronics, it'll produce goodly quantities of molten iron and aluminium oxide slag to create quite a mess - difficult to disentangle, it will render flesh indistinguishable from scorched and carbonized beef. It also has the virtue of being stable and not-so-easy to light - needing a relatively high temperature to ignite. They're also relatively lightweight to deploy on a battlefield, one person can carry several, lay one out beside a body, roll the body on, fold the quilt over the top, then use an easy to ignite flash powder to set it off. As an alternative that wouldn't require extra personnel, or equipment, might I suggest that the thermite be incorporated into the uniform itself. Sensors detecting an end to life-signs would result in automatic self-immolation, this can also be accomplished with a "self-destruct" facility, usable when death or capture is imminent and unavoidable. You could even go to the extent of placing sensors on each separate limb, such that if a soldier loses a foot or lower-arm, they will after a certain time (so as not to pinpoint the soldier's current location) no longer be apparent on the field - but leaving the soldier to continue the mission if possible. A similar arrangement could be made with abandoned weapons, additional providing for the possibility of a very effective means of arson. [Answer] # Mini-Nuke Nukes will solve any problem that requires a considerably high amount of energy being released in short time, which I figure could be about 10% of the questions in [science-based](/questions/tagged/science-based "show questions tagged 'science-based'"). We have already mathed out the amount of energy you need in order to disassemble a human body into molecules before in these questions: * [How much TNT is required to vaporize a human body?](https://worldbuilding.stackexchange.com/q/110732/21222) * [Anti Personel Radiation Incendary Long Fallout Orbital Onset Laser Sattelite](https://worldbuilding.stackexchange.com/q/108339/21222) And [here is the source](http://www.madsci.org/posts/archives/2006-05/1149017453.Ph.r.html) for the estimated amount of energy required to vaporize a person. It is around three gigajoules, which is what you get from a single metric ton of TNT. That single ton of TNT would only fully vaporize a person in very ideal lab conditions though. Most likely you would get chunks that could still be used for DNA identification. What we need is to dial things up to eleven. The smallest nuke ever made is the [W54](https://en.wikipedia.org/wiki/W54). It fits into a backpack specially designed to encase it, as seen in this image from the Wiki: [![A backpack with a W54 nuke inside, propped against a column. A fire extinguisher is present for size comparison.](https://i.stack.imgur.com/P5Tj8.jpg)](https://i.stack.imgur.com/P5Tj8.jpg) Notice the fire extinguisher, for size comparison. It is quite feasible for a black ops team to carry one or two of these backpacks. The maximum yield for the W54 is about 1 TNT kiloton equivalent. For comparison, [an accidental, disastrous, non-nuclear blast of that yield happened in 2020 in Beirut](https://en.wikipedia.org/wiki/2020_Beirut_explosion): > > The blast was also felt across Turkey, Syria, Israel, the West Bank and parts of Europe, and was heard in Cyprus, more than 240 km (150 mi) away. It was detected by the United States Geological Survey as a seismic event of magnitude 3.3, and is considered one of the most powerful artificial non-nuclear explosions in history. > > > > > The explosion overturned cars and stripped steel-framed buildings of their cladding. Within the port area, the explosion destroyed a section of shoreline and left a crater roughly 124 m (407 ft) in diameter and 43 m (141 ft) in depth. > > > [There is footage of the blast, though it may be understandably distressing to watch.](https://www.youtube.com/watch?v=93tV6-0Ugwk) If you activate a W54 warhead upon a fallen comrade, you will fulfill the hard requirement in the question about body and equipment being turned into something not recognizable. It is also a non-magical solution that is feasible with less than current technology, since the W54 is an invention from the 1950's. As a bonus, you can also deal considerable damage to the enemy side. The mininuke in your possession might also be a deterrent against retaliation or against being chased when you retreat. Last but not least - you should preferably be able to trigger it remotely so that you can put some safe distance between you and the teammate you wish to evaporate. You can figure out possible safe distances by using the [NUKEMAP](https://nuclearsecrecy.com/nukemap/) (don't forget to set the yield to 1 kiloton before you detonate). For most cities, you should be a couple neighbourhoods away just to be sure. ]
[Question] [ So in my fictional universe there is a collection of tribes which, over the millennia, domesticated a closely related ancestor to modern day lions, much like how humans domesticated closely related ancestors to modern day wolves, what kinds of evolutions can one suspect them, the lion-ancestors, to undergo? And let us assume, for simplicities sake, that they are for all intents and purposes identical to modern lions. So far what I have is: Becoming more sociable Smaller Size Increase in synaptic plasticity What other changes can on suspect? While I did find much on the neurological changes in domestication, I cannot find much on physical changes outside of those brought about by selective breeding. More Context: For more context they were domesticated in much the same manner was wolves, they were assisted by humans, and assited humans in hunting of fauna and megafauna, over a long period of time, and soon began seeing them like members of the pride, and underwent the changes that come with domestication. [Answer] I think in order to understand how they would evolve, you'd need to clarify what purpose they fulfil within your fictional society. Wolves are persistence predators, and one of the few predators in the world who can keep up with human persistence predation tactics and actually be useful for hunting things. This is one of the major reasons they have been domesticated where a dizzying array of other predators haven't. Big cats are ambush predators, and as such tend to run out of puff very quickly (but be capable of immense speed and acceleration over a short distance). This is not as complimentary to human hunting characteristics as the lions can't keep up with humans, and humans blow the lions' cover (and are too slow to effectively ambush the same prey). Cats were domesticated for entirely different reasons. They're a vermin-management service, eating mice, rats and small birds that would otherwise eat our stored grain. The process for this was less directed than with other domestication events as humans basically created environments that are great for small cats that eat mice and the cats moved in. I can't see how you'd start off with man-eating cats at this point, and breed them until they live off mice. A possible solution So, what you're looking for is a set of circumstances that would mean it's desirable for humans to work together with big cats, and importantly that it's desirable for big cats to hang around humans as well (rather than just eat them). Domestication (especially early domestication) is a two-way process. For wolves, proximity to humans (and ultimately participation in joint hunts) meant that they increased their success rate for getting food, and for cats it meant a steady supply of small vermin for them to eat concentrated in one area. You need a situation that's beneficial to both parties (and the more proximate that benefit the better). You're going to have to invent some things to engineer this situation. Perhaps some sort of animal that needs the physical strength of lions to bring down, but perhaps has a level of armour plating that means it needs tool use to butcher (or maybe has poisons that need cooking to remove, but that is a longer shot as lions would have quickly learnt not to bother hunting those). Or perhaps there are migratory animals that are susceptable to ambush-predation which gives lions a glut in part of the year, but for the rest of the time the game around is only really vulnerable to persistence predation. In the early days, humans scavenge off lion kills in the plentiful season (or drive them off them), and lions drive humans off their kills in the fallow season. Over time, this develops into humans leaving parts of their fallow-season kills on the periphery to keep the lions fed (and stop them driving them off their kills), and lions permitting humans to scavenge the bits of their plentiful-season kills they don't need. The reason I put this option second is that the benefits are less proximate, which means it's harder for both parties to see the other as a benefit and not a competitor. It's also lacking a truly collaborative hunting aspect which would reinforce the thought that both animals are part of the same group. However, it's a bit of an easier option to extrapolate from so we'll use it for the next step. So what might that mean? In terms of evolution, I think you're right that they would reduce in size slightly and become more co-operative. You might see them become faster and more greyhound or cheetah-like as that would make them better at ambush predation, and they wouldn't have the fallow-season enforcement of persistence predation checking their evolutionary change in that direction. You could see breeds a bit like servals being bred for catching birds, or large guard-breeds that spend most of the time lazing around in one location but are powerfully built. Cats can also climb where dogs can't, so they might be breeds of use for hunting arboreal creatures (although, alongside the bird-catching variants, would need to be smaller and change their hunting behaviour so would probably be later developments). Basically, in this circumstance (and any other circumstance), you need to trade the benefits of dogs (high endurance) for the benefits of cats (high acceleration) and see what uses humans could put that to. [Answer] Well, think about it like this, my dachshund looks absolutely nothing like a wolf, and yet, through a few generations of selective breeding later, here he is, a bonafide, wiener shaped, wolf descendant. > > When individuals are looking to breed animals, they look for certain valuable traits in purebred stock for a certain purpose, or may intend to use some type of crossbreeding to produce a new type of stock with different, and, it is presumed, superior abilities in a given area of endeavor. For example, to breed chickens, a breeder typically intends to receive eggs, meat, and new, young birds for further reproduction. Thus, the breeder has to study different breeds and types of chickens and analyze what can be expected from a certain set of characteristics before he or she starts breeding them. Therefore, when purchasing initial breeding stock, the breeder seeks a group of birds that will most closely fit the purpose intended. > <https://en.wikipedia.org/wiki/Selective_breeding> > > > So if you assume domestication, at even its most rudimentary level, has already taken place at the time of the narrative, you can assume that for any type of dog breed on Earth there could be a corresponding lion breed on your world. a good resource might be the [American Kennel Club's](https://www.akc.org/breeder-programs/breeder-education/akcs-guide-responsible-dog-breeding/) guide to breeding dogs. You could take up the narrative from an almost bureaucratic stand point of new laws and licensing requirements pertaining to new breeds, or overbreeding. Can you imagine a landscape of roaming semi-domesticated, hungry and neglected, lions on the hunt might look like? Have fun [Answer] They wouldn’t be much different from our current cats. Cats (of all species) are not as anti-social as popularly believed; they are as social as their food supply permits. The issue is that big cats need an enormous amount of food, so aside from lions (which hunt enormous prey), one territory can rarely feed more than one cat. However, many species of cats big and small have been observed sharing territories and even sharing kills when prey is sufficiently abundant. The wandering is the real problem with cats. The most significant difference between housecats and their nearest wild relatives is that the former have the “homing” instinct, which means they recognize a specific place as their home, whereas the latter are equally at home anywhere in their territory and will change their territory as needed to feed themselves (or avoid conflict). So, you need to either select for homing lions if they appear naturally by random mutation, or you need to somehow introduce it into your stock by cross-breeding. Unfortunately, while small cat species are remarkably inter-fertile, big cats are not, so you may be waiting a long time for the former. Another issue, oddly, is that you need to select for dumb cats. Studies show that every domesticated species has a smaller brain and exhibits less intelligence than their nearest wild relatives. My guess is that less ability to feed themselves makes them more reliant on humans and thus more easily trained or at least handled. All of that said, you might look at the many, many species of lesser cats, many of which can be almost as easily socialized as housecats without the hassles of selective breeding you’d need to shrink a great cat. The only thing that’s missing is the homing instinct, which you could transfer to them by limited interbreeding with domestic cats. In fact, you might do better starting with such cats and then trying to selectively breed them to be larger! [Answer] According to fox domestication, they would keep some of the young-age features A well-known Russian experiment is about taming and domestication of foxes. per the [Wikipedia page](https://en.wikipedia.org/wiki/Domesticated_silver_fox), these foxes tend to keep some young age features > > The changes manifested by the tame foxes over the generations, moreover, were not only behavioral but also physiological, just as Belyayev had expected. The first physiological change detected in the tame foxes was a lower adrenaline level. Belyayev and his team "theorized that adrenaline might share a biochemical pathway with melanin, which controls pigment production in fur", a hypothesis that has since been confirmed by research.[6] After eight to ten generations, the tame foxes began to develop multi-colored coats, a trait found more in domesticated animals than in wild ones; this was followed by the development of "floppy ears and rolled tails similar to those in some breeds of dog". After 15 to 20 generations, a very small percentage of the tame foxes developed shorter tails and legs and underbites or overbites. The experimenters also discovered that the domesticated foxes show a "fear response" several weeks later than their wild counterparts, and that this delay is "linked to changes in plasma levels of corticosteroids, hormones concerned with an animal's adaptation to stress". After 12 generations of selective breeding, the corticosteroid level in the tame foxes' plasma was "slightly more than half the level in a control group". After 28 to 30 generations, "the level had halved again." At the same time, the tame foxes' brains contained higher levels of serotonin. Moreover, tame male foxes' skulls gradually became narrower, more like those of females, and litters became, "on average, one pup larger" > > > I think that domesticated lions would for instance have smaller manes (the males) and maybe would keep the slightly spotted skin of the puppies. But it would not be so certain: the foxes of the experiment were bred mainly for their docility trait, but these lions could be bred for different traits. I expect that, once fully domesticated (in a time span of about some hundreds year), the human breeders would start to select different traits, according to the utility, such as size, instinct to territoriality and so on. Of course, the true problem is that lions are not as easy to feed than other animals. The only carnivore animals that were domesticated are the dog (but because wolves can adapt to eat everything) and the cat (who is an obligate carnivore, but doesn't need a lot of meat because of its size). So in case of lions, I expect that the breeders would also try to select the smaller ones, in order to have animals easier to feed. [Answer] In a video about a Russian project on domesticating foxes, the foxes started to become greyer and their ears to become more soft and fallen to the ground, like the dog ones. "We met the world’s first domesticated foxes": <https://youtu.be/4dwjS_eI-lQ> The thing is that, just like us, the more the foxes started to look more sociable, the more they looked like infant version of their species. Even though foxes and wolves aren't much like Lions and cats, you could also considerate these changes. Not to mention the social structure of lions would be severely be changed and affect their relationship with humans and other pets. Like pissing in all their territory, eating a crap-ton of food, sleeping more than 14h a day, roaring all night like dogs barks all day, ruining sofas with their powerful nails and jaws and probably eating the neighbour's dogs. BUT, if you really want to nail the way they act in a daily basis, you will need to study more about wolves/dogs and cats/lions behavior and social structures to make comparisons and build up your domesticated Lion. Also, a bonus, there is a russian couple that is raising a cougar that was too small and weak to be released into nature and was rejected by its mother. It could also be used as a reference for your lion. "Couple Share Studio Flat With A Cougar \| BEAST BUDDIES" <https://youtu.be/OkO7be9Dn2c> They also have a channel were they make daily uptades on their cougar and other wild animals they interact with: <https://www.youtube.com/channel/UCvph04Sh9CFKAw-gA6y-brQ> Also, another bonus curiosity: Cheetahs are too stressed, so the zoos give them companion dogs to help them keep calm. Depending on how your tiny-lions behave, you could also add a type of animal they are good to interact with, like cheetahs and dogs or crocodiles and those birds. ]
[Question] [ Closed. This question needs [details or clarity](/help/closed-questions). It is not currently accepting answers. --- Want to improve this question? Add details and clarify the problem by [editing this post](/posts/198231/edit). Closed 2 years ago. [Improve this question](/posts/198231/edit) There is a certain attention given to the moon in order to use its helium-3 to supply nuclear fusion on earth. But there is some problems involving energy there that concerns me. A day on the moon is equivalent to 26 days on Earth. Assuming that helium-3 is actually usable in nuclear fusion reactors, and we build a mining base there, how could we power it? Well, one would suggest to use the very own helium-3 to power it, but it would be extremely difficult to actually send the parts and build a nuclear fusion on site. We are doing some of those on Earth and it will take decades. I thought of nuclear batteries, but their energy output is small though constant. And a nuclear fission reactor is a no-no to send in a spacecraft, considering all the risks. Solar panels are really the only easy option, and circulate the entire satellite with it seems unlikely. There are also Stirling motors: they work with differences in air temperature. So astronauts could use their own body wasted heat to continuously power it. But the energy generation of said motors is incredibly small. They could use it in the border of craters to use the side exposed to the sun to heat it and the dark side to cool. But this would be meaningless since everything would be in pure darkness. There is hydrogen in there, they could use hydrogen cells to power it? Anyway, what I'm saying is that there should be other bodies in the solar system with helium-3 or just as interesting. Maybe Mercury, since it has a tidally locked orbit and the twilight zone could be easily maintain a base. [Answer] Ash has already answered the main part of your question, but I'd like to point out that your assumptions that have led you to writing off the moon as a source of useful minerals may be incorrect. > > there is some problems involving energy there that concerns me. A day on the moon is equivalent to 26 days on Earth. > > > The [lunar terminator](https://earthsky.org/astronomy-essentials/definition-moon-planet-terminator-line-twilight-zone) moves at 10 miles an hour. If you had a mobile stripmining facility and a sensible route planned out, you could stay in the sunlight. There are also multiple "[peaks of eternal light](https://en.wikipedia.org/wiki/Peak_of_eternal_light#On_the_Moon)" near the poles where solar power could be maintained continuously. > > Well, one would suggest to use the very own helium-3 to power it, but it would be extremely difficult to actually send the parts and build a nuclear fusion on site. We are doing some of those on Earth and it will take decades. > > > Not a whole lot harder than building an entire off-planet strip mine, refinery and interplanetary shipping facility, I suspect! If you can't already throw together fusion reactors with ease, you've got no business trying to get into mining the moon for fusion fuel. We've got deuterium and lithium and boron on Earth, and we can make tritium if we want. Helium 3 is useful stuff, to be sure, but it isn't the be-all and end-all of fusion power. Remember that it is noticably harder to ignite D-3He fusion than it is to ignite D-T fusion, cos that extra proton makes the coulomb barrier that little bit harder to break through. > > And a nuclear fission reactor is a no-no to send in a spacecraft, considering all the risks. > > > The risks are overblown. Fuel rods that have never been put in a reactor and used are very low radiation... vastly lower than the 25kg of extremely radioactive plutonium we just sent to Mars in Perseverance. If civilisation is at the point where big off-planet industrial facilities are a thing that can be built, safely lifting well packaged uranium fuel rods or pellets out of Earth's gravity well should be possible. And who knows, maybe you could mine [thorium](https://en.wikipedia.org/wiki/Compton%E2%80%93Belkovich_Thorium_Anomaly) up there whilst you're extracting 3He, and not fly any fissile materials out of Earth at all? > > Solar panels are really the only easy option, and circulate the entire satellite with it seems unlikely. > > > Why not use [orbital powersats](https://en.wikipedia.org/wiki/Space-based_solar_power)? Gather the sunlight in space, beam power down as microwaves, problem solved. [Answer] ### The best stocks of Helium 3 in the solar system, after the moon, [is Earth](https://en.wikipedia.org/wiki/Helium-3#Terrestrial_abundance), but the answer you're probably looking for is Uranus. (I'm excluding the sun because it's way too hard to mine) 7% of some Natural Gas deposits have helium 3 in them, there's up to ~40kg of it in the USA natural gas stockpile right now. There's an estimate of 100,000 - 1,000,000 tonnes of it in the mantle of Earth. Volcanos erupt it, its dissolved in our oceans, and a trace gas in the atmosphere. [3rd best is Jupiter](https://en.wikipedia.org/wiki/Helium-3#Solar_nebula_(primordial)_abundance), which has ~100 ppm helium 3. But that's quite hard to mine due it's 60km/s gravity well. [NASA has a report for gas giants helium 3 mining](https://web.archive.org/web/20090327051914/http://gltrs.grc.nasa.gov/reports/2006/TM-2006-214122.pdf) Saturn, Uranus, and Neptune all have some in the range of several parts-per-million. Uranus is probably the easiest to mine. That report linked goes into details of a proposed Uranus helium 3 mining operation. The way NASA is thinking of doing it is to have an orbital station with a refinery, aerostats (balloons) with scoopers that capture gas and filter it as best they can, an automated ship comes down, replaces the gas reservoir, and takes it the full one up to the orbital station for processing into fuel. [Answer] To begin with, you use batteries. Mining & processing - the major power draw - takes place during the day, and the batteries are charged. During the night, only the life support & maintenance functions are performed. As your enterprise expands, and you collect some copper or aluminum as byproducts of your mining, you site solar panels further east & west of your mining site, which allows you to extend your mining time. Eventually you have a power grid circling the moon, and can operate continuously. [Answer] The sun has far more helium-3 than any other body in the solar system. But it’s a bit hard to get at it, especially since it’s mostly in the solar core. To expand, the sun is 8% helium. Helium-3 abundance in the local interstellar cloud is [about 2.5 parts per 10,000](https://link.springer.com/chapter/10.1007/978-94-011-5116-0_27), and that’s a reasonable estimate for what’s in the sun — the solar wind has rather more, about 4 parts per 10,000. The mass of the sun is 2E30kg, so it contains about 1.6E29kg of helium, of which 4E25kg is helium-3. For comparison, the total mass of Jupiter is 2E27kg, so it would have to be at least 2% helium-3 to have more than the sun, which it obviously isn’t. ]
[Question] [ In the land of Dorn, there is an entire industry involving the wholesale of magical items. This industry employs individuals experienced in the art of magecraft to enchant mundane items or weapons and give them magical properties, or to create magical items from the ground up (fire-swords, invisible cloaks, etc). The abilities of these items respond to mana, which manipulates the item's power. Mana is the life energy of a human being, which is present at birth and grows over a person's lifetime. An individual simply touches the object and forces their mana into it to activate it. These items respond to any kind of mana and is indiscriminate to a person's signature, which allows them to be resold and used by different individuals. However, The enchantments built into the object inevitably fade with time. The abilities of the item get weaker with repeated use and eventually loses its power. This allows for return business, as the user is forced to pay for new enchantments on the item. There is a special service that this industry offers, in the form of luxury goods. These special items operate in the same way as regular commercial goods are, and are built with the same materials. However, they are specifically linked to a certain mana signature, and can only be activated by that signature. Linking a magical item's power to a specific mana signature prevents the enchantments from fading, allowing for infinite and repeated use, unlike the commercial items sold to the public. These brands are made for those who want exclusivity, such as a noble wants a magical item that can only be used by them, or a royal family wants an item that can be passed down to their future generations within their family line. There is no planned obsolescence built into the magic items from the industry, as even they don't have the power to do that. This fading of power happens gradually with items built for use by anyone. The enchantments of luxury goods linked to a specific individual or family are permanent and last forever. How can this be the case? [Answer] # It's the difference between the power source of the items. Your impermanent items are powered by "batteries". A reservoir of Mana that needs to be filled, then the item works. When this power is used up, it needs to be recharged. As with electrical batteries, performance drops with every recharge cycle and eventually becomes so low that the "battery" is effectively a dead brick. Your permanent, personalized items are not powered by stored power. Instead, they are set up with a continuous and permanent power-tap to the owner. As this powertap does not undergo the cycles of charge and discharge of the impermanent items, there is no wear and tear on the power system. They will last as long as the power source (the owner) lasts. Obviously setting up such a powertap requires a much higher level of skill, and thus commands a much higher price than the impermanent consumer goods. This also means that the moment the owner of a permanent enchantment dies, the enchantment dies with them. It also brings a potential danger that owning too many, or too powerful, items could be hazardous to the owner's health. There will definitely be a need for a decommissioning service. If you are tired of your childhood enchanted bicycle, you cannot just abandon it in the shed and go get that enchanted ornithopter you saw advertised. The bicycle would still be draining you, and everyone know just how power-hungry enchanted vehicles are. You will need to get the bicycle professionally scrapped before you will have the excess power available to safely enchant your flying machine. [Answer] The Permanence Comes At A Cost The luxury items are linked to a specific mana signature, yes? How do you think the enchantment is maintained? Simply put, this link binds the mana of one specific person into it when first activated, then draws upon that person's mana to keep its enchantment "fresh" and functioning in tip-top shape. Regular enchanted items don't have that kind of power, so they can't replenish their energy and thus become weaker and weaker, their power and abilities fading as they lose power. (Like a cellphone; it doesn't work as well as its battery goes down, now does it?) Luxury items don't have that annoying weakness, but you're literally paying for that convenience with your life. Just some of it, a few months or years perhaps, but that's still a pretty steep cost. Any smart noble won't like that, so one of four things will happen: 1. They'll buy luxury items, but only use them when they have to (ie. when the benefit outweighs the cost) 2. They'll buy luxury items, but have them activated by and/or used by trusted servants (who may or may not be aware that this is because they're considered disposable) 3. They'll demand a change to the enchantment; instead of one person having to pay the cost to activate the item, the cost will be shared among a group of people when that item is activated. In other words, instead of one person paying a steep cost to activate and use that item, a group of people will distribute the cost amongst themselves. 4. They'll demand a different change to the enchantment, so that every time they want to use their magic items, another individual will pay the price instead of them. These individuals will probably be bound by a special rune so that their mana can be taken and harnessed to power luxury items. They may even be brainwashed to think this is an honor. [Answer] The nature of the spell requires some flaw in its perfection: it can not be used everywhere, at any time, by anyone. One such flaw is that it is temporary. Another such flaw is that it can only be used by people with a certain condition, such as this person here, or a member of this family. It would also be possible to create things that can be used in only one place, and yes, it would be possible to use this flaw for an object that can't be moved, or would not be useful in any other location. The ability of people to exploit a flaw does not change that it fits the magical rule. [Answer] ## Pounding a square peg into a round hole: Your common magical items can be likened to a child's toy made of soft materials, and with holes for variously-shaped pegs. Every peg is different, and you pound on the board with your peg until you get it through a hole somewhere. Taking your mallet and hammering a peg into a board wherever it can be forced in is ultimately destructive. But give an adult the same toy, and they easily and nondestructively can put the same peg in the same hole a thousand times. Another analogy would be joining two boards with either random nails or precision screws with predrilled holes. If the two boards are screwed together though the same holes, they can be screwed and unscrewed over and over with little wear. But if you hammer the boards together with nails in different spots every time, the boards get more and more filled with holes until they finally start falling apart. So imagine that mana is like an irregularly shaped object, and so are enchantments. Bang together a person and an item, an you can make it work. But bang it together often enough, and a soul is made of a lot tougher stuff than a magic item. Your precisely matched magic item is like a pre-drilled board made to line up with predrilled holes. A general user pounds on a magic item every time it's used. A precision magic item effortlessly matches up with it's dedicated user and hardly suffers any noticeable wear at all. For a single person, the level of precision is probably perfect. The item is likely to last forever for that person (great for a vampire...). For an inherited item, I'd guess the item would follow a set of characteristics, and the closer the inheritor was to the item's "shape," the better it would work with less wear. But children aren't prefect matches for their parents (and are only half genetically identical) so you'd likely have certain members of the family that would be a better match than others. Unless there's inbreeding, the item will get finickier with each generation, and the imperfect match would eventually wear on the item. One day it would quit working, and if enough generations had passed, the warranty would have expired or the business that made it would have gone through a hundred mergers and acquisitions so trying to get your money back for your "forever" family artifact will be a challenge. Such is life - nothing lasts forever (except that vampire's stuff). ]
[Question] [ Okay, so I have a world just like ours, except all the myths are real. Maybe. The Masquerade is in full effect - there is no such thing as monsters and you'd be crazy to say otherwise. This is vastly helped by the fact that most monsters either look like humans or hide fairly effectively. There is also a small government branch that helps with ID and all that if you're a law-abiding monster (and sends hunters if not). Of course, no disguise is 100% foolproof, so you occasionally need excuses. A Vampire might claim having migraines to explain their need to stay out of the sun, or anemia for their pale skin and need for regular blood donations. Werewolves might actually go with a fake disease like Lycanthropy and just claim the doctor who discovered it thought it was funny because the symptoms match so well (eyeroll). Hormone imbalance linked to moon phases and all that, gets really painful with cramps and seizures... children sometimes suffer hallucinations, too. Explains everything. I'm kinda stuck on what to do with my ghosts, though. Depending on their strength, they are either invisible unless you know how to look, or they look like regular people. There is some in between, but for the sake of the question, let's assume the ghost is powerful enough to look fully human. Visible, tangible, smells mostly human (some incense, too), even his shadow and reflection align, he's breathing and has a pulse. Assuming he fakes all of that well enough, the only thing that betrays him is the light behind his pupils - so faint you can't see it unless it's really dark, but it flares badly on camera. Everyone has cameras nowadays. Another problem is that the ghost can only leave his haunted house for a limited time. How long varies with how much energy he has - he might go on a lengthy vacation one time, or be stuck indoors for months at other times. His comfortable average is three to six hours a day, which is little time to get a job if you look young and healthy enough to work fulltime. So, in short: 1.) How does the ghost prevent being exposed when he mustn't be caught on camera with his eyes open? 2.) What (medical?) condition could explain his inability to work full-time/ leave the house at times? [Answer] > > 1.) How does the ghost prevent being exposed when he mustn't be caught on camera with his eyes open? > > > [Partially mirrored contact lenses](https://www.colouredcontacts.com/gb/view-all/1029551-silver-mirror-coloured-prescription-contact-lenses-30-day.html?SubmitCurrency=yes&id_currency=4). These come in different strengths and he can mess around with a camera in selfie mode to find the strength that disguises his glowy pupils by reflecting light from elsewhere. That site offers all kinds of variants that allow one to change their eye colour and other crazy stuff. He may be able to get by with a simple semi-opaque lens as used by cosplayers when their eye colour doesn't match up with their character. > > 2.) What (medical?) condition could explain his inability to work fulltime/ leave the house at times? > > > Covid19 explains why I've been working at home for a year. Even before covid19 there was jobs advertised as work remotely full time - some job sites even allow you to filter by that. Allowing staff to live away from an office saves everyone money. If you want an actual medical condition, I'd suggest MS - I live with someone with MS, some good days she's full ability, some bad days she can't get out of bed, and some medium days she needs a wheelchair. It totally explains why sometimes he can party for days, and sometimes he disappears for months. [Answer] > > 1.) How does the ghost prevent being exposed when he mustn't be caught on camera with his eyes open? > > > Work from home office, use deep fake technology if you need to participate in videoconferences. It also just came to me that a lot of youtube channels I watch are infotainment channels hosted by animated characters (TheOdds1Out, Brew, Sam O'Nella Academy and CGP Grey come to mind). > > 2.) What (medical?) condition could explain his inability to work fulltime/ leave the house at times? > > > The ghost might just tell everyone he is an incel. People will be glad that he doesn't leave his house. On a more serious note, there is a condition called [Hikikomori](https://en.wikipedia.org/wiki/Hikikomori) - I could swear there was an English term for it, it was common among World of Warcraft players years ago. > > The Japanese Ministry of Health, Labour, and Welfare defines hikikomori as a condition in which the affected individuals refuse to leave their parents' house, do not work or go to school and isolate themselves away from society and family in a single room for a period exceeding six months. > > > Failing all that, the ghost might be just extremely obese. [There is a very american reality show that documents the life and times of people too heavy to leave their own beds](https://en.wikipedia.org/wiki/My_600-lb_Life). --- > > Another problem is that the ghost can only leave his haunted house for a limited time. How long varies with how much energy he has - he might go on a lenghty vaccation one time, or be stuck indoors for months at other times. His comfortable average is three to six hours a day, which is litte time to get a job if you look young and healthy enough to work fulltime. > > > That's called being an introvert. Half the world was already like that even before the pandemic, and I'm not counting just millenials, Gen Z or whatever the current generation is. [Answer] * Preventing the ghost's eye's from being recorded on camera. The use of glasses due to perfectly plausible living conditions such as migraines/light sensitivity/partial blindness. The glasses have a tint/sheen to them that blocks any camera's ability to record the eye feature you are worried about. As for face to face encounters, any living beings paying enough attention to notice the eye feature, can explain it away as a trick of light reflecting off the glasses. * how to explain ghost not leaving the house Same medical conditions mentioned above could explain most of it away (while partial blindness shouldn't be a reason to restrict oneselve to home, it can be used as an "excuse"). Your ghost also tells ppl that he works odd hours and doesn't keep a 9-5 "normal" office schedule. No one would bat an eyelid at that. * Also note, that unless you are actually spying on your neighbour, do you know how much time they spend outside the house (precovid)? Your ghost can certainly play off that with such idle chatter whilst taking out the rubbish or over the fence gossip about how he went to the shops earlier in the day or got stuck in that traffic jam that was conventiently broadcast on the radio that morning. How are your neighbour's or friend's who don't live in same street as you, to know when you left/returned to the house. I mean, they would just assume wouldn't they. [Answer] Your ghost could claim to have agoraphobia, a psychological condition which makes leaving the house extremely difficult, even traumatic to the sufferer. As for avoiding being photographed with their eyes open, just avoid being photographed at all. All modern cameras are electronic in nature and ghosts have influence over electricity as proven by the flickering of lights during hauntings. Just short out all cameras and cellphones within the confines of the house. From there, maintaining the masquerade requires only a warm-bodied assistant to visit the house on a regular basis, delivering empty groceries (eating is for the living) and take out the trash (last week's empty groceries). ]
[Question] [ I imagined a hypothetical planet named after Bacchus (a nickname given to Dionysus, the Greek god of wine, ecstasy, parties, theatre, drama, comedy, tragedy, and spiritual madness). Its main characteristic is an ocean composed of a mixture of water, ethanol, and sodium chloride. Also, Bacchus is smaller than Mars but bigger than Mercury. There is a breathable atmosphere. However, there is no life at all. What would be the conditions for my world to exist? (I ask for a scientific way.) [Answer] ### Extremely unlikely but just borderline possible. Since ethanol evaporates at a lower temperature than water, it may rain ethanol before it rains water. This will not be pleasant, less "champagne shower" and more "metholated spirits in the eyes", and will kill plants and may even stop life from evolving. Without life, theres no fermentation, which is the easiest way to make ethanol. It also means you cant rely on plants to make oxygen, you need to rely on geology to absorb carbon dioxide and make oxygen. There is a way to create [ethanol without fermentation](https://news.stanford.edu/news/2014/april/ethanol-without-plants-040914.html) using carbon monoxide, copper derivatives and electricity. I think you need to rely on this. The rough process would be: * start with a ball of rock with a carbon dioxide & carbon monoxide atmosphere. * rock gets hits by ice meteors, giving an ocean. * ocean dissolves some rock, making salt. * after weathering, some copper outcrops are exposed. * static electricity gives lightning impacting the copper and or salt water. * copper + carbon monoxide + power = ethanol. Ethanol is slowly made over millions of years. * sub ocean crust slowly dissolves, exposing a carbon sink and releasing oxygen into the water. The ethanol vapour in the air would be quite potent, its dependent on air pressure and such but I wouldnt want to go there without at least some air filter, otherwise I'd dehydrate and pass out drunk just from breathing the air. As Williks answer points out; The ethanol would gradually escape the planet, but at the quantities we need for an ocean it would form ice-like particles along the orbit path, essentially a new ring system of solid ethanol, and ice, some of which would reenter the planet and return to a gas form years later. It wont last for ever but may allow the ethanol ocean to last another few thousand years. (Queue comments enforcing the point of how unlikely this is to occur) [Answer] It will be cold on Bacchus. [![escape velocities ](https://i.stack.imgur.com/7TlTP.png)](https://i.stack.imgur.com/7TlTP.png) [Here is a fine graph](https://en.wikipedia.org/wiki/Atmosphere#Structure) showing escape velocity for various atmospheric gases. The more massive the planet, the lighter the gas molecules it can hang on to because more massive means higher gravity. The colder the planet, the more light gas molecules it can hang on to because when it is cold molecules are less frisky. You stipulate your planet is between Mercury and Mars in size. Even full Mars size and temperature is too small to hang on to its water, much less ethanol. Triton is between Mercury and Mars in size and it has kept its water because despite its small size it is freaking cold. Your ocean of ethanol, salt and water will be frozen all the way down. Maybe you can breathe the atmosphere with a warming device, and a big one. On cold days you might need to dig up some atmosphere with a shovel. ]
[Question] [ The year is 21XX. Scientists developped something able to permanently transform a sentient living being into another one with the same level of sentience. The transformation possibilities range from small cosmetic adjustments to changing a cranky old lady into a galloping young centaur boy while conserving her identity. Depending on the complexity of the transformation, it takes from a couple of minutes to a few weeks. The twist is, they are still able to determine one's original identity with a DNA test. Since the transformation is literally morphing the subject's body and not just putting an illusion or a VR helmet on them, how do they do that ? Did they also tweak and enhanced the DNA test ? Is it an advanced case of [chimerism](https://en.wikipedia.org/wiki/Chimera_(genetics)) ? [Answer] You can enable and disable genes by using [DNA methylation](https://en.wikipedia.org/wiki/DNA_methylation), this does not change the DNA composition by itself. You can also change gene expression throughout the body by many means such as precise hormone level tweaks. It will not make you a bird but it may easily let you grow extra hands or tough skin or claws or whatever. Consider also game modding, which can turn Half-Life into Counter-Strike or Warcraft III into DOTA - 0 of game code bytes changed. Genetic modding similarly, may choose to avoid changing actual genes at all. [Answer] ### Totally plausible - Assuming nanobots can create faster than cells can regrow As a massive simplification, DNA determines how your body will rebuild itself when repairs are needed. This is not the only factor in how the body currently looks - wear and tear, how much exercise I've done, makeup and hair, what clothes I'm wearing, and what drunk decisions I've made at the tattoo parlour, all contribute to my appearance. Like annotating a printed page with a pen, I can change how something looks without changing the original document in the computer. When the page fades and it needs to be reprinted, my annotation will be gone, because I didn't modify the source, but if I diligently reapplied that annotation everytime the page is reprinted no-one would be any the wiser. So your method of altering the body needs to use some other process - the most plausible is tiny little nanobots that either recycle existing cells that are not needed for their raw materials and then creates new cells of the required type, or destroy cells and take their place directly - a cyborg but with nanobot size tech. Over time your body will try to "repair" itself, the nanobots need to be fast enough to stop this from taking place. They may also need to suppress and replace the immune system too. So long as you replace failed nanobots quickly, and keep them powered, and properly firewall them so no-one can hack them, this should work fine. The PCR test we use for DNA testing is very sensitive and DNA spreads everywhere (forensics are full of "detected DNA from a brief touch" stories) - so long as there are some original cells in there somewhere (eg you can decide "must keep brain - and thus must keep heart, lungs, etc.") you'd be able to get a DNA match. [Answer] Vat grown body but original brain. My own genetic code is limited in how awesome a body it can produce. If I want an awesome body I will need alternative DNA. Fortunately there are many alternatives available and during my time in the vat, the process will substitute my original parts for vat grown parts with my original parts apoptosing and dropping away as they are replaced. New parts are HLA matched of course so my immune system does not take umbrage. My brain however holds a vast trove of song lyrics and cookie recipes. The brain is irreplaceable. The body must be grown around my brain. Subsequent brain biopsy will confirm my original identity even though my svelte new body has only Oddrigue DNA. [Answer] Yes it is very plausible if you don't significantly change body plan, or body chemistry. Extreme plastic surgery. With plastic surgery can add horn like bumps to a skull, add a non-functional tail. This is not done because of risk, expense, mostly non-functional appendages, and stigma of "why would you choose that?". Obviously this does not change DNA if source tissues are the persons own body. Major problem of plastic surgery is hooking up nervous system. If this were solved, prosthetics would be a thing of the past. To change major skeleton elements ie tetrapod to hexapod and have those change be functional will be beyond science for much longer time frame. Growing limbs via stimulation. Search for "Michael Levin" regrow frog legs. This person's research is able to cause limbs to grow on frogs. Something like this may able to create more functional body parts. So directed growth of new limbs combined with plastic surgery can gain many forms, more limited by budget and can a persons mind adapt to the new body. [Answer] Change everything, except reproductive organs Changing someone into insane and complex shapes will require a full overhaul of the DNA. To achieve certain shapes it's likely you'll go through many DNA sequences in between to get there safely. You might be able to lock away the original DNA in the cell while the new DNA does the work, but that is wasteful in energy and maintenance of the body. Even though it might be possible, any society would likely still choose for the low cost option of changing the full DNA strain. But there is something that everyone is likely to want to do and needs to have a clear, concise and most of all identical for all humans. Reproduction. People are unlikely to want to give up making children via sex. If you want to reproduce you need to have compatible DNA, so everyone would need to have this basis. Likely human babies would still look like humans, as not changing the already accepted method/shape is easiest. A body would be fully changed, except for (parts of) the reproductive system. Although people might still require some changes before sex can be initialized (you don't know beforehand if they'll meet a cat or a centaur), the reproductive system is ready and has the original DNA. The immune system can make exception for other DNA, like with organ transplants or a duozygotic twin having pieces of a brother or sister growing inside them. So it is doable. This can be a strong real reason for still being able to see the original DNA. Unfortunately it doesn't help in crime cases or something if you need it for that. If you need that, possibly (parts of) the skin can be forced to still contain the original DNA. [Answer] Have you noticed that when lizards lost it tail it growth again, but that does not work for human. And I believe that why your idea may work. Your morphology is a complexes process that could not be determined by DNA alone, other factors such as your environment and epigenetic may play a role. But after 25 years old human stop growing. If the body is changed by surgery like operation after this age. I see no reason the body would take back is original form. Your growth is over. Your body have indeed limited repair function, but not that large. I don't see how the DNA could drastically impact the morphology of a grown up human being. ]
[Question] [ It must be roughly the same size and height as an At-at and walk on legs, but it does not have to have all of the other At-at features. So no laser cannon or similar, but it can have missile launchers and machineguns. It can use gas turbine engines or a small nuclear reactor (if required) for power. Bonus point: this would be very expensive and vulnerable to missile and artillery fire today. But if it were to appear in a real world medieval setting it would presumably be a fairly effective weapon? Would medieval level technology military forces have any way of stopping them? At-at details can be found here:<https://i.redd.it/xantjcb4m1tz.jpg> [Answer] ### Give Airbus, Boeing, or Cat a call. The atat is an exercise in size and hydraulic power. That's really all you need to achieve parity with what you see in the movies (ignoring any "walk AI" - I'll get into that later). If only we were able to find some company that can make large metal equipment with powerful hydraulics: [![enter image description here](https://i.stack.imgur.com/3wgiG.png)](https://i.stack.imgur.com/3wgiG.png) Airbus and Boeing both should be able to build a large metal thing with powerful hydraulics - plane flaps and landing gear need to exert considerable force comparable with moving a leg this size. Many large shipbuilders should be able to do a good job too. Cruise ships have powerful rotating engine pods for precision port docking and powerful horizontal stabilisers to stop rolling on high seas - another big metal thing with powerful hydraulics. ### More of a DIY guy? You could probably build an atat (or better) in your backyard Assuming a big backyard, mechanical experience, hydraulic experience, and an unlimited expense account at the local hardware store. 4 legged walking robots are doable with modern tech; As pointed out in comments; Boston Dynamics has filled youtube up with their research on this guy: [![enter image description here](https://i.stack.imgur.com/ayiKT.jpg)](https://i.stack.imgur.com/ayiKT.jpg) I dont remember atat being particularly nimble or stable. I reckon I even saw the pilot manually positioning the legs, so technically this ai beast isnt even needed for parity with the original movie. You can build AI-driven table top walkers out of current-tech Lego parts and an arduino. (My high school robotics team in 1999 was able to build a robot to play table top scale soccer.) It's more a question of size and hydraulics. And yes, you can build something this large at home; people build things approaching this size and detail for Halloween. Eg this two story atat: [![enter image description here](https://i.stack.imgur.com/Q6n94.png)](https://i.stack.imgur.com/Q6n94.png) A skilled mechanic with enough room and raw materials should be able to build a functional, full size atat. A generator, a hydralic pump, few actuators, some piping, and $200,000 worth of random metal parts. Done. ### Could it be defeated in a medieval battle? Yes. If you copy the original atat it could be defeated by surrounding your castle with gentle hills or by digging a ditch - the centre of gravity is so high and the leg motion is so minimal they'll topple over on any uneven terrain. I'd rather take the CAT dump truck into battle than an atat. Combine decent walking ai with modern hydraulics and better leg design and the battle will be more in favour of the atat. [Answer] ## Look To Logging: If we're looking at walking machines, try this one on for size. The [John Deere Walking tractor](https://blog.machinefinder.com/3255/john-deere-walking-harvester) is designed to move freely in rough terrain with soil that can't tolerate wheels and tracks. The basic design is a working vehicle, used in real world situations. While the basic engineering of building a big one hasn't been done (largely because it's impractical) the concept works and is in use. You could easily envision the large arm replaced by a flame thrower without significant redesign. A self-loading artillery/rocket launcher/ recoilless rifle would be easy. Missiles could be easily attached. A minigun would be also quite simple and would deal with most of the threats such a vehicle is likely to face (in rough terrain, you'd need to engage infantry and aircraft). So you'd want to make it lower to the ground, for practical reasons, and with more legs. But a walker tank? Slow compared to a modern main battle tank, but it's not really meant for terrain you can take tanks into. So the next time you're invading rural Canada, arm and armor some oversized walkers and go at it. [![Walking tractor](https://i.stack.imgur.com/SAL7t.png)](https://i.stack.imgur.com/SAL7t.png) ]
[Question] [ Every time one arm is cut off, two more grow in its place. The two new grown arms have 70% of the strength of the previous original arm and 100% of the control and dexterity. It's just that the arms grow indefinitely, the more they are cut the more they split.... Theoretically one could have a 100 toothpick thin arms. If the arm is cut at the shoulder blade, it splits into two shoulder blades, if it's cut at the shoulder socket, a new socket which can accomodate for two arms grows in its place and if the arm is cut below the shoulder it will just be one arm that splits into two like the blue monkeys from the movie Avatar... That one with the sexy aliens not the one with the twinkletoes. In case of too many arms, how does one deal with the problem? Maybe 3 or 4 are cool, but 12...well good luck sleeping or doing anything really. Is there any way to block the growth that doesn't involve big brains and highly developed medicine? [Answer] You mention that 2 arms grow only when an arm is cut. An obvious solution seems therefore to constrain one of the 2 arms after the cut, so that it becomes atrophic and leaves more space to the other, free, arm. An atrophic limb reduces basically to just something more than its bones. [Answer] You don't. I propose a frame change, in that not having anything to stop the multi-arm situation is not a bad thing! Obviously anything that manages to lose that many arms is unfit to live! Based on the second half of your question regarding big brains and medical tech, I'm assuming these guys are supposed to be cavemen/primitive, but sentient. If so, there'd be a lot of cultural stigma in having too many arms. A tribe or culture may have coming-of-age rituals where arms are removed (you are a man now, you need 6 arms to join the raiding party/you are a woman now, you need 8 arms to carry children etc.) but eventually having like 20 arms (or whatever arbitrary number you settle on) only shows that you keep getting your arm hacked off. Your limbs aren't effective for much of anything, and you obviously aren't smart/skilled/lucky enough to avoid serious injury. At that point your creature is just like a cripple in primitive societies. The society might try to take care of them if they've got some special rank (priestess, or old war hero for instance) but generally speaking they're on their own and quickly dead. On the other hand, having an egregious number of arms could be a sexual signaler. Like how males of certain bird species are colorful with un-aerodynamic showoff feathers which signal to potential mates "Look how inefficient I am, I must have wildly good genes to still be able to survive." So your creature might see many-limbed creatures as "sexy" because hey, they got their arm chopped off 15 times and managed to live and regrow all those arms. They must have something genetically that makes them superior! At some point of course this runs into your 100-toothpicks argument and the thing can't support itself. But if sexual selection has taught us anything it's that said markers of sexual fitness can end up being hugely detrimental to the individual and yet somehow the species soldiers on. [Answer] Give yourself a loophole The usual one is fire. Either you use a red hot blade to remove a limb, pour tar into the wound, or just shove a burning branch in the hole. Fire is a traditional way to prevent excessive bleeding and is a standard loophole for this sort of problem. For example, how to kill a hydra: > > To defeat the Hydra, Hercules called on his nephew Iolaus for help. As soon as Hercules cut off one head, Iolaus would cauterise the wound with a flaming torch so that nothing could grow to replace it. - [Wikipedia](https://simple.wikipedia.org/wiki/Hydra_(mythology)) > > > [Answer] Remove the arm entirely to go back to two arms. When an arm is cut off a joint grows from the wound. From this joint grow two new arms. Cut one of these arms and you get a total of three arms. Here's the important thing: The joint itself still counts as one arm. So if you cut through the the joint you end up with two arms and not three. That means you can always reset to two arms by cutting the arm off entirely at the shoulder. ]
[Question] [ Werewolves in my setting turn during full moons. They appear very wolf-like aside from modified hips, legs, arms and neck allowing for a bipedal stance in addition to the quadrupedal stance. Mass redistribution occurs when forming the tail; no mass is added. One werewolf had their tail severed by an axe right before daylight, clean swing right at the base. They turned back moments after. Reattachment of the tail to the base of the back was necessary for keeping it alive until the next full moon when it will be reabsorbed. The werewolf in question has their tail in human form till then. Could it be successfully hidden from view or otherwise explained? EDIT:The world is a planet very similar to modern day earth, with two major moons. both at low inclines ~2°,5° and orbiting at 1,4 orbital resonance (7.25 and 29 local days respectively) total eclipses happen far more frequently than on Earth. total Solar and total Lunar eclipses flip the physical and mental states of a werewolf respectively. e.g. werewolf mental control switches to human during full moon this they'd be in control during full moons. day state stay as human. direct contact with full lunar light when direct sun light is below 500lux triggers transformation. Locking a werewolf away, from direct sunlight, during a full moon until a solar eclipse will result in their full moon state being locked physically as a human. conversely exposing them from sunlight directly, avoiding the brighter stage of the full moon, to a total lunar eclipse will result in their day state being stuck as a wolf. The biology stays the same, e.g. blood will remain human O- not change to DEA (dog blood). War being fought between the neighboring countries needs more blood supply. Being discovered would result in the character being kidnapped (involuntary conscription) and converted semi permanently into a physical and possibly mental wolf for use as a military dog substitute. Werewolves are compatible with human soldiers as blood bags, live longer than a dog, capable of incognito spying, loyalty can be beaten in by muzzling or exposure to total lunar eclipse, dehumanizing treatment. [Answer] She's got a ponytail. She's got a ponytail. She's got a P-P-P-P-P-P-P-P-Ponytail! <https://www.youtube.com/watch?v=BDg6-v9V8lo> [![pony tails](https://i.stack.imgur.com/D6l97.jpg)](https://i.stack.imgur.com/D6l97.jpg) That's right. Do not watch this video unless you are ready for these cartoon girl birds to carve a new groove in your brain, from which they will continue to play this song, forever. Fortunately your lycanthrope character had long flowing locks to start with and mixing her severed tail in there just fills it out and looks great. Sort of a hair extensions thing. It would not surprise me if keeping her tail stuck to the back of her head becomes a regular habit, because she also likes how the mass redistribution to make the tail leaves her pants a little less snug. [Answer] Short answer: Yes Long answer: There are a bunch of ways you can go about hiding or explaining a werewolf tail. You can wear extra long backpacks that extend to your waist, and stick your tail inside, that could work. But the most foolproof way is to go to a cosplay festival and pretend to be a furry, you would blend right in, and no one will ask any questions. If your werewolf is smart it'll be fine. [Answer] Simple: Put on a long, flowing skirt, and keep the tail in the skirt. ]
[Question] [ Imagine an Agrarian civilisation (whose entire economy is based on producing and maintaining crops and farmland.) had developed a way to cultivate something like [Cable Bacteria](https://en.wikipedia.org/wiki/Cable_bacteria) into large basic circuits (able to do basic arithmetic, but at a larger scale that modern day circuits. Think the size of a [breadboard](https://en.wikipedia.org/wiki/Breadboard) but organic, with inputs for the cable bacterial to attach to.) What is their one pressing need, of this agrarian nation, that this new technology addresses? I know for instance, the [Aeliopile/steam engine](https://en.wikipedia.org/wiki/Aeolipile) was more or less just a plaything to Hero of Alexandria, so it's possible the bio-circuitry serves them no purpose. But if it does solve an agrarian civilisation level challenge, what one biggest thing would it solve for them? (I am trying to ascertain something like "X, Y, and Z are the biggest issues most agrarian societies encountered. This cable bacteria does/doesn't solve any/solves this one the most.") If it matters don't assume anything beyond bronze age technology, something like the ['Indus Valley Civilisation'](https://en.wikipedia.org/wiki/Indus_Valley_Civilisation#Technology). The main thing is, that the majority of the populous is growing and selling crops. [Answer] Accounting, as simple as that. The agricultural revolution was also the dawn of record-keeping, which entailed tracking surpluses and deficits, setting prices for exchanging goods and calculating profits/losses, taxes, tributes, tithes and rents: in other words an economy. Your bio-circuity would likely be put to use in these areas as areas of influence and trade grew with the rise of empires. Calculating seasonal changes and patterns tied to astronomical cycles, which can have significant agricultural implications, would also benefit from these early computers [Answer] They sell it to someone else If a society is based on purely agriculture, it's producing more food than it need and not enough tools, finished products, luxuries, etc. This means it must be trading them to other societies and buying back the finished products it needs. [Answer] Telecommunications seems like the biggest thing. I think agrarians tend to be spread-out, so any communication tech faster than horse messenger would be hugely welcome. It's not just about convenience, either. Consider that even if food and supplies must be hauled overland slowly, coordination is itself a problem that flows from glacially-slow information transfer. This is a society that has seen starvation because information about unexpected food or supply shortages wasn't disseminated quickly enough to be actionable. And because so much of their economy consists of perishable goods, timely and accurate information is vital. Whenever there is a mismatch between what gets shipped and what is needed, lots of people suffer. In the best case, surplus goods are sent to where they are not needed, and so the people who produced those goods lose their investment. That by itself can lead to major hardship. In the worst case, unanticipated needs are not met quickly enough, and lives or crops are lost. Oh, and even though they're agrarian, it's not like food and farming are their only concerns. War, politics, crime, disease, natural disasters, predators -- wherever there are people, these problems are too, and people need to talk about them. They need information about the facts, and (unless they are all at war with each other) some will want to coordinate their responses. --- The Western genre can only exist in one place: the boundary between wilderness and civilization. One of the clearest harbingers of the coming of civilization -- the eradication of the wilderness -- is the telegraph. A society without the telegraph is still the wild west. Throw in a steam engine and you're practically living in post-WWI America. --- ETA: second place might be electric lights. Electric lights are superior to fuel lamps for a few reasons (including that they don't spew toxic smoke directly into living spaces), and so electric lights can be adopted more widely than lamps. Artificial light allows diurnal creatures like us to be productive for longer each day. I imagine one of the biggest impacts is just that it means farmers suddenly have more time to read, which means education, which leads to literally all the good things. Education is the closest thing humans have ever found to a silver bullet. But even if you don't want electricity to let them bootstrap their way to smartphones and credit-default swaps and dark web chat bots, it'll make a big difference simply being able to do the paperwork and read the latest farmers' almanac after dark, instead of those things competing for daylight with the farm work. ]
[Question] [ I have a space based setting and would like to develop a mechanism that counters radiation damage. Here is my idea: The setting 100 years from now. A cellular organelle is developed similar to the CRISPR tool and human beings are genetically modified to carry it in all its cells). The organelle reads through the cell's DNA looking for telltale signs of radiation damage (specifically gaps in the DNA strands). If the organelle locates one of these gaps it releases a protein that signals cytokines to destroy the cell. If the organelle fails to find a gap it simply continues to read the DNA? Would this approach work? If not how would this system have to be modified to work? If it cannot be made to work what system could achieve increase radiation resistance for human beings? [Answer] This is a very cool mechanism---looking for strand breaks is definitely the best marker. I think the body might have a process for repairing single-strand breaks, and your mechanism would kill the cells instead, so that might be an issue. Double-strand breaks often lead to cell death anyways. My worry here is that this doesn't prevent a lot of the acute effects---it could definitely cut down on cancer, but a fair number of the acute effects are direct results of "hey you just killed a bunch of cells" and this doesn't fix that. On the other hand, if what you're worrying about is chronic exposure to low doses---and that's what it seems like---then this approach would work! It's not going to let someone go and hug a reactor (or even carry around a gamma cookie in their pocket), but it is definitely plausible for reducing cancer risk. As another note, there's not a ton of data on low-dose health data---most of what we have is from bomb survivors and cancer treatment---so as long as it's plausible (which this is) you should be good to go! [Answer] *Genetic custom nanites with hard-wired DNA code:* So part of the problem with DNA repair is that if it happens too fast, the cells start to engage more radical solutions to fix damage - sloppier repairs, because alive and mutated is better than dead. This is fine for a bacteria - either the repair works, and it lives, or it fails and dies. For a multicellular organism, the cell that lives but grows out of control is cancer. Any actual DNA can be altered, so let's overwrite DNA. Your organelle can hold a copy of the person's DNA code, but made out of some coding material that is essentially indestructible at a cellular level and unaffected by radiation and mutation. Everyone gets a gene scan as a child, and receive injections of manufactured nanites programmed with their own code as needed. Got cancer? Get injected, and the nanites enter the cells and rewrite the DNA to the original code. Cancer stops. You're going into space and there's lots of radiation? Inject in advance, and add nanites as new cells grow. The nanites could also be tied to a tiny machine implanted that can make new nanites, but my thought is you want ZERO chance of mistaken code, so external and unalterable is better. The nanites avoid the need for apoptosis, although a targeted form could still be used to rebuild damage from tumor growth (digest tumor, lay down new extracellular matrix for stem cells). The body has lots of mechanisms to slow growth and replication that have downsides in adults as growth slows. The people with these could heal faster safely, possibly even regrow lost tissue. Imagine being resilient like a small child all your life. This could even immortalize people regularly treated and reverse aging. Imagine a corporation selling immortality, and you always need another shot to counteract cells that replicate quickly. Cha-ching. A slightly scary alternative would be nanites without code, that were connected to an external input with the patient's code. Wirelessly, the patient receives coding allowing a doctor to repair damage and even alter the person's DNA to respond to changing conditions. An unscrupulous corporation or government could insert DNA for obedience, alter their employees to live in alien environments and then leave them there (unable to return because they're no longer Earth-compatible), etc. The evil possibilities are endless. ]
[Question] [ Context: I'm looking for justification of the above in my story so I can have clandestine artists. But I'm having a little dificulty finding a situation in which art becomes to inherenty detrimental that not even it as a hobby is well seen and it requires actions outside of the law~! Maybe a lack of resources? [Answer] Destruction of art as representative of unacceptable thought. This has happened many times. French Revolutionaries destroyed cathedrals and art. The Soviets and communist chinese had strict rules governing what sort of art was acceptable. The Nazis on taking power famously burned piles of "degenerate art". The most recent example I can think of is the Taliban in Afghanistan. <https://en.wikipedia.org/wiki/Destruction_of_art_in_Afghanistan> > > Taliban insurgence/occupation Upon the resurgence of Taliban rule from > 1996-2001 the ban on most forms of art and cultural expression was > immediately implemented.[2] The Taliban’s war on art was inspired by > the Koran. The Koran forbids the portrayal of living things, whereby > drawing or sculpting living things is recognized as a direct affront > to the Almighty.[15] Among the initial acts of removal were dragging > paintings out of homes, book burnings containing art work, public > execution to TV sets and the discontinuation of music.[16] In 1996, at > the very beginning of the Taliban's rise to power, the entire card > catalog archiving the art at the Afghan National Museum was burned in > order to keep the rebels warm.[17] The systematic destruction of > museums and their collections, to include film archives were purged to > cleanse them of the "unIslamic" depiction of the living and human > form.[2][16] > > > In your world, art must celebrate the values of the ruling party. Art which does not do this is degenerate or heretical or treasonous. Persons interested in making such art must do so in secret. It is not farfetched at all. [Answer] This has been explored by Orwell in 1984. Art does not follow IngSoc. That makes it Thoughtcrime, together with love and any non-Insonc thought. Thoughtcrime is dealt with by MiniLove. They Will take Thoughtcriminals and reeducate them. Make them see that Big Brother loves them, that they love Big Brother. Room 101 is just a tool for that. [Answer] I believe there have been multiple strict religious sects that forbid art and decoration. The most strict Amish fit this description. As I understand it, the reasoning is that it is a distraction/vice away from the devout life of hard work they believe in. ]
[Question] [ Another element of my meta-setting was the Foundation. What they exactly do changes from story to story, but they're usually a peacekeeping force, low in numbers but insanely powerful. One reason for that, other than asking the help of more-or-less demons, is that Foundation employees undergo a "very special" training. Thanks to the magnitude of forces they deal with, operatives frequently die horrible, horrible deaths. Being sawed in half by an aggressive spider robot, possessed by Phil Swift; or torn to shreds by a .50 cal happens every week for rookies. The catch? They don't have my permission to die. I keep those neatly locked up in a safe at the bottom of the Mariana Trench, along with every N-word Pass. In practice, whenever an operative dies, they respawn either at the Security Department or where their corpse was placed, depending on the extent of the damage. It depends on the story, but this is supposed to make them even more dangerous. "Well duh, they can't die so they can accumulate EXP freely and be extra reckless! What's the question?" A strawman would probably say. Well, there is something else I was curious about. Basically, *I wanted this "I have died before," thing to explain why Foundation operatives seem to be able to ignore physical pain and charge at you even when they've sustained so much damage they look more like moving corpses. Structural damage still affects them, so no legs == no walking. But could that level of pain tolerance actually be possible to achieve via this "training"?* Memories of operatives can be slightly altered (redacted, to be exact). Also, an operative's memories can safely be streamed to the backup device up to a second after the heart stops, so they should clearly remember their agony. The Security Department's regenerators (that regenerate the corpses and imprint the backup into them) can heal just about any wound, including those that were sustained from overstraining muscles. Usually, the rebuilt fibers are stronger just like with bodybuilding (well, there's still a limit). Note: Foundation employs other species, but I want to focus on humans. Also, rookie operatives are entirely normal humans. [Answer] Traumatising your soldiers will make them weaker Your soldiers will remember the suffering and the powerlessness of their deaths. Combine this with a cultural expectation of macho-ness and not expressing emotion, and you've basically created an army of PTSD suffers. They will get into battle and go into an automatic mode. That may include freezing, fleeing, or they may just hurt everyone around them, including their own friends. I've witnessed someone have a PTSD attack and try to flee (drunk by car), their friends calmly tried to stop them driving drunk, and the friends got hit with a beer bottle, punched, kicked, stabbed with keys, and eventually hit with a moving car. The urge to flee for this person after being triggered was more important than any other thing, including the law and their entire social circle. The PTSD tried to sacrifice every friendship they had for a trigger. This isn't behaviour you want in your soldiers. To use your technology to create a soldier who doesn't fear dying: * Once pain crosses a threshold (that you find with experimentation I guess), the recording of it is turned off. You want them to understand some pain (otherwise they'll panic when they feel it for the first time, "I stubbed my toe and it feels worse than my last 15 deaths!"), but you don't want them to remember agony. * Once fear crosses a threshold, the recording of it is turned off. Same again, you want them to remember feeling a little nervous, but full blown panic as the world fades to black should be erased. * Same with humiliation, degradation, and worthlessness. Death in combat is rarely noble. When someone relaxing in a portable toilet takes a surprise RPG hit, they shouldn't remember the humiliation of dying pants down, face down in a tank of excrement. They need to be able to look back on that emotion free; That memory needs to be considered hilarious and laughed about at the bar after finishing for the day, rather than humiliating them for years to come. * You want the soldier to wake up and his emotional state is "Oh no I let my team down.". Add this emotion if it isn't there. * Edit out repeated deaths. If the soldier is dying the same way over and over, say, 3 identical times, delete the oldest memory. You want them to throw themselves at the robot spider over and over, and you want them to learn from their mistakes and try different things, but you want them to think that this time has a decent chance of being different. * (If your memory recording technology is this advanced), make their memory of the battle longer, with a stronger enemy, but much closer to being won. Instead of being sawn in half by one spider robot, there were 50, and as a team they slaughtered 49, but the last one got them. Then when they respawn they see one spider and think "Oh this will be easy, I've already killed 49 of these things". When it kills them again, their memory is implanted with the memory of killing another 30 of them, etc. Basically you want them to believe they almost succeeded but just messed up a little bit, even if they've been throwing themselves at that same robot spider for weeks. Your canon fodder should avoid feeling frustrated and demoralised if at all possible. [Answer] Repeated exposure to pain might decrease pain tolerance instead of increasing it. [Pain tolerance](https://www.wikiwand.com/en/Pain_tolerance) has two major aspects: 1. pain receptors' sensitivity, and 2. perception of pain. Repeated exposure to pain may make pain receptors more sensitive to stimuli and lower pain threshold and tolerance. The more you poke someone the more painful it becomes. Perception of pain is how we react to pain. If we can ignore the pain we can tolerate higher levels of it. The most effective ways to improve this aspect are [exercise](https://bjsm.bmj.com/content/bjsports/32/1/20.full.pdf) and cognitive training. Send your rookie operatives to the training camp for several months. Get them through rigorous physical training. If you can personalise programmes in such a way that each operative is always close to their limit you would get better results. Establish mandatory physical training routines for all operatives after graduation and do regular fitness checks. This is basically what modern armies do. You just need to improve on it a bit. Cognitive training involves psychologists and psychotherapy if necessary. You want all your operatives to learn [meditation](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6128533/) techniques. Calmness reduces the perception of pain while [anger, sadness](https://onlinelibrary.wiley.com/doi/pdf/10.1002/acr.20230), and anxiety increase them. Make sure that none of your operatives suffers from [depression](https://watermark.silverchair.com/1-1-45.pdf?token=AQECAHi208BE49Ooan9kkhW_Ercy7Dm3ZL_9Cf3qfKAc485ysgAAAqIwggKeBgkqhkiG9w0BBwagggKPMIICiwIBADCCAoQGCSqGSIb3DQEHATAeBglghkgBZQMEAS4wEQQM7IC-rXXz_u0AsCyNAgEQgIICVQygEo1y2yEkwYNwuKOAhIip7Fite0-vY-_N3PaogRmI4UXweHzeU9U69HzUOECsGBhfEo9XU1Xq41x4idkmUJV_KjLC-m8smTgHJzJgmCMskM2kDgTjF4iiWdrAskyLIuUPPbV0RmqYXCIUEP5hyPKzntIZvkIycZd055GN0zzuZh-ikGFAvk5l4mFgRdNxOXPIqla_3KYyxgwwHHMjj8FzOCU0uUfDm3KVS-KbDcYayohNULFqWeRUpmm0XtSHOxQeF311pu00DD6ABhfVojgmrmuqSIvwI5PZe3qHMH3UjGZdAUhjPtaSCkovfSG8p4tRUVLXgK7HU2JFyrnUTVy2Hfu9qCOTnDAmvcl93unvgJzFlGONT37iUj2JO0zF_oMp_7miBFVDGh05RmSdP5g4ZcWagqYia6yND8-hFgFT_O6EfwAnT4JBcrr8krH_q1JI8iMJcPPHCx2zTojD46O3sXTvn1cGuviEijV6EBhboIp9uOHHcPLuUdAHdc__Arimik7uk2MnYjctO_qLrS3YkDW0gfM7GNBukFLGNn5EXwtjoAgt7cLRnnrmDHkuQysRNNEfbiOz5iKvm4h20U4BIs5v9rX1rsHGCcqG6ngch97zMSBFFCGdLIw__QrdPv1bE7FtRSMe7ajLSo3Y8nXGjagAeW0AfL499wJklKYnoumQEI6Oug95sWCKK1HZsz2ukq1PRbEB3LEfDuT8SuEZtgkJ_0EyBW1BXM0VaaelGu5sEvKa51MgzHCGKBVmNDVhtNf9rzwK9pCbfiSoMTgiy7g_YQ) or other mood disorders. Divide operatives in pairs or small tactical units. A [mere presence of another person](https://www.sciencefocus.com/the-human-body/why-can-some-people-handle-more-pain-than-others/) was shown to increase pain tolerance, at least in men. Also, provide them with enough [sleep](https://www.frontiersin.org/articles/10.3389/fpsyg.2018.02089/full) and good nutrition. Encourage [swearing](https://medicalxpress.com/news/2020-06-traditional-ability-tolerate-pain.html) when in pain. [Cheerfulness and a good sense of humour](https://www.zora.uzh.ch/id/eprint/77579/1/humr.2004.009.pdf) would also be great. Your psychologists can help with developing cheerful attitudes. If your technology allows it, [increase the number of opiate receptors](https://www.sciencedaily.com/releases/2015/10/151023121910.htm) in the brain. This would lower sensitivity to pain and increase tolerance. Psychological counselling should be mandatory after each operation. A revived operative must go through psychotherapy, no exceptions. As other people mentioned, PTSD is a very valid concern. For example, up to [30% of US veterans suffer from PTSD during their lifetime](https://www.ptsd.va.gov/professional/treat/essentials/epidemiology.asp). The prevalence is higher in males than in females. This relationship is reversed in the general population. [Answer] Special forces training and controlling the pain In all special forces trainings pain is part of the training. However, the Spetsnaz Russian special forces are famous for it. Being hit with wooden sticks, concrete blocks broken on their heads by sledge hammers and being dragged behind trucks are just the most ibvious. They are starved, undercooled, overheated, sleepdeprived and more. They are learned to like the pain and to never stop until either your body fails or the enemy is defeated. This seems to be exactly what you want. The problem is that most don't make it. You need physically and mentally incredibly strong persons. If they aren't they'll just psychologically break down, requiring years of therapy. Even the ones that make it can be described as emotionally damaged, but in a deliberate precise way. You can't get all foundation humans to undergo such training and keep working. Too few would be able to continue. Making it work Pain is useful, but up to a certain point for your employees. If you have regeneration technology, you can probably also limit their pain. You can use this with training and regenerating to show there's nothingbto fear. Intentionally damaging them with their consent, starting with something small and regenerating them afterwards. This will give them the feeling that after pain, they are fixed to 100% and feel good after. They'll even see and feel the improvements to their strapping body! You can ramp up the pain until that threshold is reached. Then you can even start killing them. First quick, later slower deaths. This way they'll get used to it in a safe and relatively good environment, feeling the protection of the foundation every regeneration. This can make them more reckless, but together with a self preservation culture they'll not do too reckless things overall. A good foundation member only does dangerous things when required. Only if required, they'll rush in, confident in their regeneration and do their best. Altering their memories can be done sparingly. If the pain does get too much, remove or reduce the pain, but nothing else. Much like mothers forgetting the incredible pain of child bith so they still want to have another kid, foundation humans would be willing to go the length again. Just make sure the stories are known that it can hurt much more, or they might feel betrayed when it happens. If they know it might happen but their memories tell them they never experienced it, they will risk such things. Like people telling not to watch 2 girls 1 cup, eat the most spicy pepper in the world or touch a Gimpy Gimpy leaf, it'll be too difficult to imagine it, so they will chance the possibility. This still is the best scenario. I think most people would psychologically accept this, even though it might still create a lot of psychologically imbalanced people. There will still be drop outs, but I guess you'll need fresh meat for some purposes anyway. [Answer] Unlike computer flash storage, memories aren't just "files" but rather physical arrangements of neurons and connections in the brain. When you learn something, new neurons are formed, retrained, or connect themselves differently. This means if you "copy" a brain neuron-by-neuron, the copy will have the same memories, personality, etc. Similarly, someone's pain tolerance is also (in part) a component of their neural structure. Therefore, it's reasonable to assume that when you resurrect your operators, pain tolerance will be include along with memories, reflexes, attitude, etc. That said, you might want to do something to prevent your operators from being overly traumatized--when humans are in extreme high-stress scenarios, the brain can change very quickly or receive lasting damage in response to the situation (that's where PTSD comes from). [Answer] Dose them on painkillers, or they’ll end up broken and unusable. I’m not a psychologist, but I think PTSD is caused by pain, stress, etc. So repeated exposure to this through death and regeneration will not make them storer, but traumatise them. Instead, dose them on painkillers. Now they experience death, but it doesn’t hurt. The first few times they’ll have a natural aversion, but as they learn it doesn’t hurt, they’ll lose this. We get this to a degree in games - games which allow quick respawns with little loss train players to use their characters as disposable - e.g. in some games I’ll happily use a rocket launcher at point blank to make things easier for my teammates, knowing I’ll respawn moment later. Whereas ‘gritty’ games with no respawn and no save force you to be cautious and careful, and you feel the pain more. Soon you’ll have an army who don’t feel pain, and don’t value their individual lives, just the contribution they can make to the overall goal. They’ll happily drown themselves so their squad mates can stand on a pile of their bodies and cross the river. They’ll still be broken as humans, but they’ll be a disturbing and powerful force. You’ll need some way to keep them in check. A pleasure drug is boring and may make them lose their edge. Perhaps give them a strong taste for fine dining? So squads who are effective are allowed the use of 5\* chefs. ]
[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/177206/edit). Closed 3 years ago. [Improve this question](/posts/177206/edit) I have heard there have been multiple instances of this happening prior to the current president's proposal. Could this have seriously happened some time in the 20th century? [Answer] A question of politics, not economics. In the 17th and 18th century, kings could sell land, or give them as dowry. In the 19th century, national sentiment became stronger but kings still lingered. The [Louisiana Purchase](https://en.wikipedia.org/wiki/Louisiana_Purchase) was in 1803, the [Alaska Purchase](https://en.wikipedia.org/wiki/Alaska_Purchase) was in 1867. After that there was a double standard when colonies could be traded, or conquered, but that couldn't really be done to "real" nations -- "real" as the established, non-colonized nations defined it. Look at the trouble with [Alsace-Lorraine](https://en.wikipedia.org/wiki/Alsace-Lorraine), or how the France failed to detach the [Saar](https://en.wikipedia.org/wiki/Saar_Protectorate) from Germany after WWII. By contrast, look at how [Poland](https://en.wikipedia.org/wiki/History_of_Poland_(1945%E2%80%931989)#Border_and_population_shifts) was shifted westwards by the Soviets. So, assuming that the US is the "Leader of the Free World" in your alternate history, the key thing would be to convince the Greenlanders that they want to become Americans. * First step, in the late 40s and early 50s there are massive American bases in Greenland. To make a political statement, dependent housing is later built for these bases similar to the housing in Germany, just better insulated. * Second step, the US Dollar becomes the informal currency in Greenland, simply because of the purchasing power of the American airmen and their families. After a few years, this is legalized. Soon the Danish Krona disappears from use. * Third step, there is a political dispute between Greenland and Denmark which is not about independence but some other factor. A majority of Greenlanders believe that US statehood would be a better deal for them and they start a campaign. [Answer] A Greenlandic Missile Crisis In the immediate aftermath of WW2, the Danish Communist Party (which had been at the core of the country's anti-Nazi resistance movement, and was reasonably popular in the real world until the mid-50s) does much better in Denmark's first post-war free elections, and ends up leads the governing coalition. With the support of the Soviet Union, the Danish Communists eventually force out their junior coalition partners and institute a one-party state, making Denmark an eastern bloc country. By the early 60s, the USA has begun encircling the USSR with ballistic missile installations, including in Turkey (as per the run-up to our own Cuban missile crisis). The Soviet Union co-ordinates with the Danes to position nuclear weapons in Greenland, ostensibly to guard the island against invasion, but really to show to the USA that Soviet missiles pose just as much of a threat as US missiles pose to the USSR. In the stand-off that ensues, Kennedy refuses to make the IRL quid-pro-quo of removing the missiles from Turkey, and Khrushchev stays similarly obstinate. In the end, the agreement that is reached is that the USSR will be paid off, with a huge financial payment to be made from the USA to Denmark (technically, with that money to ultimately end up in Kremlin coffers) in exchange for the transfer of sovereignty of Greenland from Denmark to the USA, and with it the removal of the missiles. Greenland becomes a US territory, though the only settlement to take place is via the establishment of military bases. [Answer] The Danes have sold territory to the US before. <https://en.wikipedia.org/wiki/1916_Danish_West_Indian_Islands_sale_referendum> In 1917 the Danish government sold the Danish West Indies to the US for $25 million in gold. These became the US Virgin Islands. In your alternate timeline, the Danes see an opportunity with this agreement (which both sides had been working on intermittently for decades). A recently independent Norway in 1917 is disputing the Danish claim to Greenland. If Norway prevails, Denmark has nothing. If they sell while the US recognizes their claim, they come away with profits. Denmark adds Greenland to the territorial purchase agreement for an additional 15 million in gold. The low price is because of the disputed nature of the claim. For its part, Norway accepts $5 million in gold to abandon their claim. This is inside the 20th century by 17 years (as mandated in text of question) but earlier than the 1945 start date in the title of the question. [Answer] World War 1: * This is similar to Willk's answer, but it's what first occurred to me. Denmark is more friendly with Germany during WW1, or allied powers declare the mining of the belt to be a violation of Danish neutrality, and as a result Greenland is stripped from Denmark in the restructuring at the end of the war as punishment. <https://encyclopedia.1914-1918-online.net/article/denmark> The US is rewarded with territorial concessions for its aid in the war. If the 1945 timeline is needed, something similar could be done at the end of WW2. [Answer] Let's make Greenland one of the topics of [Yalta Conference](https://en.wikipedia.org/wiki/Yalta_Conference), held in February 1945. There, Churchill, Roosevelt and Stalin had decided what post-war world would look like. It is conceivable that USA would ask for control of Greenland, and not impossible that other superpowers would accede to this demand. Of course, USA would have to yield something back in return, but this would be for you to decide. ]
[Question] [ Could a horse-like creature have human-like hands as its forefeet without changing the way it moves? [Answer] Short answer: No, sorry. Long answer: You see, horses are ungulates, meaning they walk on the tip of their digits. This was a process that took a few thousands of years to happen, resulting in the fusion of some digits, as well as hand bones, and loss of the others. Horse hands are quite differently structured than ours and aren't composed of the hooves only. Technically, these are the horse's hands: [![enter image description here](https://i.stack.imgur.com/do0R9.jpg)](https://i.stack.imgur.com/do0R9.jpg) Human hands on the other hand, are great for grasping, climbing and holding stuff, but if the way you walk doesn't hint that, it's been a couple thousand years since they've last aided in walking, if at all (nowadays it's assumed we evolved from a primate which didn't knuckle walk). Additionally, walking on all fours using only the tips of your fingers and toes (be careful though) should give you an idea of how much pressure the horse's hooves need to support, and how much the different pressures mattered to reach a forelimb anatomy that looks so different from ours. So summing up, trying to put human hands on a horse structure and expect it to run is not that different from putting human hands in a bat and expect it to fly (both are cases of limbs being highly specialized to [fit a certain purpose](https://www.biologydiscussion.com/animals-2/adaptation/top-9-types-of-adaptation-in-animals-biology/59849), which will not be able to function as intended if such drastic changes occur). Edit: remember that hooves are much better at absorbing impact and avoiding injuries while running than our hands (see how people who deal with construction work and similar physical tasks tend to naturally develop stronger and more tough-skinned hands to help avoiding injuries and cuts). Additionally, our fingers could get in the way due to not being adapted to bend bend in a direction that'd be opposite to their normal flexing direction. We also need to remember horses don't have quite the range of movement our arms do, as they evolved to move in a 2d plane (left and right), while we came from an ancestor that moved in a 3d plane (left, right, up and down), so even if it could have hands in the place of their phalanxes, I don't think it'd be able to use them as we do (further anatomical changes to allow for such movement would further impact on what makes it such a good runner). If what you need is grasping ability, remember that options such as prehensile tongues, lips and/or noses have been used by other ungulates (giraffes, rhinos and elephants are all ungulates, even if some don't look like so). [Answer] If you were willing to compromise! The hoof is a modified finger. So, you could have regular fingers around it. I'm not sure how useful that would be, but technically, it would both have human-like hands and be able to move normally. [Answer] Get down in a kneeling position, legs and forearms on the ground. Note that the elbows touch the knees. Now observe how a cat or dog does it. Same thing — the elbows of the front legs touch the knees of the back leg. Now, watch a horse do it. The front hooves touch the back knees. When a cat or dog runs, they put their feet way out in front of their front knees, and they pull forward with their front legs. A horse extends their 'knee' way out in front and the feet are tucked behind the knees. When a cat or dog jumps a barrier, they extend their paws first. If their front foot touches the barrier, it is the sole or pads of the foot that makes contact. When a horse jumps a barrier, it puts its knees way out, and tucks the feet back under the body. If the front foot hits the barrier, it is the top 'shin' that hits the barrier. Humans, or any animal with front paws or hands, would jump like the dog or cat, front feet first, not like the horse, knee first. It's all about how the front leg joints bend (the joint in the position of the human elbow, although in the horse it isn't really the elbow but the wrist) in the horse vs. the dog or cat. So the method of running and jumping is totally different between the two. ]
[Question] [ This is a follow up question to [Sky of Earth and Seas of Sky](https://worldbuilding.stackexchange.com/questions/176419/sky-of-earth-and-seas-of-sky) I have a medieval fantasy setting where people live in a vast expanse of giant caves contained in a sort of giant [Stanford torus](https://en.wikipedia.org/wiki/Stanford_torus). This is not quite a true Stanford torus though; it was created from a rapidly spinning disk shaped planetoid about 100,000-200,000 years ago. Rather than building a whole mega structure themselves, the "gods" who built this habitat took this pre-existing planetoid and just encased it in a "firmament" which is an unobtanium clear shell that keeps the oceans and atmosphere from flying away. The result is that the outermost level of these caves have many lakes and oceans through which you can see a sun, moon, and stars, and the water has a day night cycle. The sun shines through bright enough to provide light for a dense forest of plant life on the ceiling of the cave. The apparent gravity is about 1G and points outward toward the seas due to the planetoid's spin imparting a greater than gravity outward force. Most of the forests are suspended hundreds of meters above the water. My original thought was to feed this canopy of trees with water from the clouds that form off of the lakes and oceans similar to a [Cloud Forest](https://en.wikipedia.org/wiki/Cloud_forest), but as I've read more into this I don't think this will work. Cloud forests have the water vapor condense on the leaves and then fall to the ground as rain where it moistens the soil. But, in this case, the condensation would fall away from the roots. I'm also concerned about soil fertility since dead plants would presumably fall away from the ground both choking up the seas by blocking out the sunlight and depriving the ceiling of nutrients needed to sustain the forest. This question: [How can I water/soil upside-down trees and grass?](https://worldbuilding.stackexchange.com/questions/57568/how-can-i-water-soil-upside-down-trees-and-grass) is similar, but in their scenario, they were not really looking for a particularly fertile or ancient upside down ecosystem; so, they were able to handwave away a lot of my concerns that it was a mediocre ecosystem for plant life. How would I create a stable ecosystem where this forest gets enough water, nutrients, and sun light to be sustainable? A best answer will be one that does not require any of the builders' technology/magic to still be doing things to maintain the cycle, but this is not strictly necessary. The trees themselves are assumed to be evolved or engineered for this environment; so, while I need them to be photosynthetic tree like organisms, they do not necessarily need to be any existing species of tree. A best answer will stick to adaptations that already exist in plants, but this is also not strictly necessary. I need the seas to remain clear enough to see the sun, moon, and stars; so, a best answer also needs to avoid situations where the water gets all mucked up with plantlife and debris over time; so, if a method does not actively recycle the nutrients back up to the plants, it should explain how the water is kept clear, where the plants get more nutrients from, and why such a method would be sustainable over hundreds of thousands of years. [![enter image description here](https://i.stack.imgur.com/d3uXF.png)](https://i.stack.imgur.com/d3uXF.png) [![enter image description here](https://i.stack.imgur.com/sv3gj.png)](https://i.stack.imgur.com/sv3gj.png) [Answer] You need a way to remove sediment from the sea floor and move it to the roof of the cave As far as I can tell the biggest problem here is keeping the floor clean. All life in the ecosystem is going to produce some sort of waste that will fall to the floor. This also means that nutrients will over time migrate from the cave ceiling, and organisms would evolve to make use of the nutrients on the lit floor and break them down into a fine sediment, so essentially soil. Very quickly the sea floor would become completely covered, and even if you were to make the surface ridged, the valleys would quickly overflow with sediment. On top of that, the trees wouldn’t have any reason to be trees and grow tall if they aren’t competing for sunlight. This will naturally create a canopy as tall as they can possibly can grow, meaning that the ocean floor would be covered in a dense canopy. So what we need is someway to move the sediment from the sea floor to the rocks above, and to make it difficult to for life to exist on the sea floor. My first thought that wouldn’t fit your needs super well is just some sort of hand wavium powered paddle that sweeps the dirt away every ten years or so and deposits it in a cavern in the ceiling, to prevent it from falling back down where the trees can get to it. This will always work so long as the machinery is working and sufficient caverns can be dug. Another solution I had is a biologically engineered bottom feeder that lives on the sea floor, and very quickly gobbles up the sediment and grows fat. It’d preferably have no anus and instead a large bladder that collects it’s waste. You could Also have them just obsessively eat their own feces and have an extremely slow digestive system. I picture this as an army of shrimp like creatures and living on the sea floor, with a sucker mouth looking that have have a ever growing butt, similar to [honeypot ant](https://en.m.wikipedia.org/wiki/Honeypot_ant). Then once it reaches the maximum weight it can transport to the ceiling, it’d crawl up the rock walls in your diagram to the roof. To us this would look incredibly strange but to the inhabitants of this world it’s just be a natural part of the ecosystem like migrating birds. The organism would need to be extremely effective and also stay on the floor it’s entire life. It could even be so effective that any plants growing to close to the floor would be immediately eaten It’d have a very quick life cycle that ends with the creature flying or crawling to the roof of the cave, burrowing deep into the rock, reproducing and then immediately dying. Then, once born the offspring would immediately burrow out and fall to the ground. Biggest issue with this guys would be preventing evolution. Over time natural selection would lead to these creatures simply staying on the sea floor and gaining a more efficient digestive system. Even if their reproduction was asexual and produced perfect and they had a crazy effective immune system that prevents all disease, mutations would still arise after enough time The only real solution I could think of to prevent this adding some sort of technological solution to this. Perhaps each one of them contains a some sort of robotic core that independently prints an embroyo, another robotic core, and a encases this in an egg. This certainly isn’t the most elegant solution and turns them into robots essentially. They’d also need to get enough metal/silicon/unobtonium throughout their life cycle to make more robotic cores. Maybe add another organism living on the roof, smelting the metal and dropping it the sea floor. Another solution would be to to make them immortal, and have insane regenerative tissue. Instead of dying on the ceiling they’d just fly up to bury their poop. This probably wouldn’t last as long as if you stick one of them into a blender, they’d have to either die or each little bit of tissue would regenerate, and could possibly lead to mutations arising from the separate clumps. Maybe some combination of the two would work. Another possibility for an engineered organism would be a tree like creature that produces a large hallow trunk leading to the sea floor, and it would produce some sort of suction and vacume to the sediment to the cave ceiling. Bottom line though, the only evolution would lead to the floor being covered pretty quickly. If not tree leaves or algae than dirt. Creating a engineered crature would likely fit the medieval setting better than a machine, but a handwavium mechanism would likely last a lot longer but might look strange in this setting [Answer] This idea might create some new problems, but perhaps to aid the integrity of the torus mechanically, and to aid with some of the problems with debris covering the outer portion of the torus where people have pointed out the incoming light could be blocked. Figure not drawn to scale. The green dot could be a tree... The arrows are where light can leave the light guide. This could be done where the thin lines are. [![Torus with light guiding for interior illumination](https://i.stack.imgur.com/e7xKy.png)](https://i.stack.imgur.com/e7xKy.png) The poorly drawn diagram is meant to show that there could be light guides capture the light and direct it to the interior the structure. This could be pretty efficient since total internal reflection is not lossy. In the region with the darker lines the totally internal reflection layer is protected on the outside. In the thinner lines of the light pipe the light can be allowed to leave the light guide in a controlled direction. This is similar to how an optical fiber works. One way you can let the light out is through the aperture at the top of the pillar (like the end of an optical fiber), or you could also design in patterns that either frustrate the total internal reflection letting the light out, or scatter the light out by changing its direction so it escapes the critical angle. These structures are also big, so you could also have internal mirrors or other optical structures. By the way, optical fibers these days do not have to be solid glass, there are photonic crystal, and "holey" optical fibers. You can also make sensors where you pipe the light to an area, let the light interact with the surface and what you want to sense on the surface etc. To the people and trees in the interior of the torus these "sunlight pillars" would periodically rise up out of the landscape providing illumination. The upside down trees might be genetically engineered to have a very strong photo-tropic response so they want to grow away from the soil and to the light. To sprout and grow against gravity there might also have to be genetic engineering since normally sprouts want to grow away from the center of the earth. The light piping structures could also be used other ways. There potentially could be other connections that could pipe the light to other places in the structure that would otherwise be dark. The could penetrate all the way into the soil layer and provide some illumination into the interior of the caves. The shape of the pillars rising out of the sunlight side could be sculpted to direct the flow of water and debris that might fall to the transparent surface. This could direct the water to areas were the light was guided and concentrated and turn it into vapor so it could be carried back up to the tree and soil/cavern layers. Perhaps it could even burn or vaporize organic materials to help with the cleaning of the optical side of the torus. If you can control the index of refraction as a function of position, you can also focus the light and make graded index lens this kind of technology could be very versatile in moving the optical energy around. For the vaporization of materials part, the main concern is having enough optical energy on the outside of the structure, since the brightness and how much you can focus the light is limited by what eventually boils down to the violating the second law of thermodynamics. However, I am assuming the Torus is pretty huge. In general, being able to control where the optical energy is turned into heat should also give you a lot of engineering flexibility, and maybe help with the climate control. [Answer] i dont quite get your question since you ignore my comment, and i know i probably get backlash from this since i dont know much regarding plant,science, or physic but i try to help...... based on my question on other site i suggest to make hanging/aerial roots or vines like banyan tree or mangrove types of roots where it develop like stalactite type of roots. [![enter image description here](https://i.stack.imgur.com/NAR7B.png)](https://i.stack.imgur.com/NAR7B.png) to collect water its up to you how long you want the roots is.... maybe it can take the water droplet if it only reach sunlite caves, but i suggest it to surpass the water at least so the roots can be a substitute or assist to do photosynthesis like assimilitory roots to collect sunlight, get water and nutrients from the dead plants and maybe it can help clearing it out, or make it work like carnivore plants by making the roots or vines that can constrict and entrap animal that touch it assuming the water or the sunlite caves has animals in it to get nutrients or to stuck it to the soil. [Answer] What a fascinating question. You have many questions rolled up in your premise, so I will try to answer the most pertinent ones, though that would still be just scratching the surface of what would be a fantastically intricate ecosystem. Keeping the sea "floor" clean, and water cycle I will start with this because the other two areas reference my thoughts in this section. For your firmament's glass-like surface, I would suggest either a hydrophobic or self cleaning hydrophilic surface. I know that the hydrophobic surface can be made permanent by micro-structures etched into the surface. This would keep the water, and the things contained within it, separate from the surface due to surface tension. Due to internal reflection, the water's interface with the glass would look silvery at oblique angles, while being more or less clear when viewed straight on. The hydrophilic coating is another option that actually binds the water and particles to it, and uses UV light to break down the molecules. This is used in some self-cleaning windshields. It might have less of an internal reflection issue than the other one. In my opinion, the best solution to gather debris dropping into the ocean is to use the currents in the water itself. You have a number of ways to induce currents. One of the best forms would be eddy currents, or vortices, because they have a tendency to gather particles inwards to the center. This could be partially due to structural members protruding like pillars in the water, and the overall motion could be provided by the Coriolis effect and temperature convection, since you are using a rotating habitat. * Option 1 Of course now you need a way to get that organic debris back up to the ceiling, so one option, since in your graphic that you have pillars in the cave like area, that you make these the center of the eddy like currents with hollow central tube structures. These can act like straws that will suck debris up from the bottom and redistribute it through the ceiling via percolation. As for the power source, you can use a heat differential pump powered by the sun. The fluidyne (<https://en.wikipedia.org/wiki/Fluidyne_engine>) is a type of Stirling engine with no moving parts that can be used to move water and last practically indefinitely. You could use a lens built into the firmament to create a hot spot and use the water to cool the "cold" liquid piston. * Option 2 Using mist and condensation to give the plants moisture seems to be feasible in my opinion, as you can have structures that would absorb and wick water upwards. Plants already have a mechanism for transporting water upwards via capillary action and negative pressure caused by respiration. Essentially, allowing the water at the top end to evaporate to draw up water behind it by creating a decrease in pressure to fill. However, this would not solve the problem of losing organic matter to gravity, which ends up in the water. Bits and pieces will fall over time, and that's not something that can be raised into the air via water droplets very easily unless you have something breaking down organic matter in the ocean. If you did, that would not make the ocean area very hospitable to life. I'm not sure whether or not that's a good or bad thing in your case, but that way, you might be able to aerosolize the dissolved organic matter along with the water to get it back up to the plants without using a direct fluid pump. You might need to do something to purify water that slowly breaks down organic materials though. Maybe filtering or boiling it would be enough? As for how to aerosolize the water, I feel I should at least throw some idea out there. Of course there's evaporation, but to supplement it, perhaps solar heated areas like geysers that have nozzle or sponge like mineral formations at the top that would produce steam or mist? Perhaps the heat of the geyser would deactivate the organic dissolving compounds, allowing vapor and condensed water to be safe for humans and plants to consume. - [Unrelated, but interesting thought - You might consider other possibilities than a seamless clear "sky". It might be interesting, for instance to have a cellular mesh like firmament that resembles something like a dragonfly's wings, or a hexagon lattice. Just my two cents.] The issue of structural integrity of the ceiling and root systems One could imagine an ecosystem where no soil is left anymore, but is made of recycled plant matter held in place by a constantly regenerating matrix of plant fibers.There could be a multi generational tangled organic mat of roots, fungi, and bacteria built on the decaying framework of the old, using it for material, nutrition, and as a scaffolding framework for building upon. Some plants might not even have life cycles like earth plants, but bud asexually, or be colonies of smaller organisms that are periodically replaced. Maybe even they could be similar to coral. Or perhaps there's a tunnel digging ant like creatures that open up new tunnels, that when they migrate, they abandon that nest, and it provides new avenues for plant growth. Porous rock or sponge like organic growth medium with strong fiber reinforcement could make up the ceiling while allowing water and nutrients to percolate down from above. There are tube like calcium formations and things akin to natural fiberglass you might be interested in. If adhesion to the ceiling is an issue, tap roots could act as main supporting elements, which the rest of the plants can focus around and use for support. Nutrient recycling Fungi, bacteria and nutritionally complementing plants sharing by-products via root systems. Certain plants benefit from one another's by products, which prevents the area from becoming nutritionally depleted. You might look up the term "companion planting" for ideas on how this might work. The fungi will be especially important for recycling dead plant matter. Plants practially always exist side by side with fungi and bacteria. The bacteria fulfills some important roles too. One would be nitrogen fixation which transfers the nitrogen in the air into organic compounds that can be used by plants as a sort of fertilizer. [Bacteria could potentially evolve into disease and blight, which would be a problem for asexually budding plants. Perhaps they could communicate with their roots chemically and kill off a buffer zone barrier to create a wall to contain/quarantine the disease. Like a fire break in a forest. There is actually some evidence that trees can use fungal networks to share nutrients and for threat signaling.] <http://www.bbc.com/earth/story/20141111-plants-have-a-hidden-internet> At least for Earth plants, nitrogen, phosphorus, potassium, magnesium, sulfur, and calcium, and hydrocarbons, are particularly important for their growth. Notice that these elements are opposite sides of the periodic table. Having a concentration of one side more than the other will result in an overly acidic or basic environment. Plants need a certain balance of these elements to grow properly. Not sure if you wanted to get that detailed, but I thought I'd put it out there. - Anyway, that's just about all I have on the matter! (Although one could potentially write books on all the possibilities here. These kind of questions are why I come to this site! So thank you for the fun question!) [Answer] The most likely outcome would be aquatic plants that spread upside down leaves across the water surface. And / or plants that grew across the unobtainium envelope at the bottom of the sea, this could drastically reduce the light levels in the cave. But assuming there is something in the water to prevent plant growth there then plants might anchor outside the cave entrance and grow in and down. Assuming the cave is very large and still has plant coverage away from the entrance then they would have to cling to the ceiling. If there were many irregularities, cracks and ridges this would help and ledges in the wall especially so. Water and nutrients might reach such plants through the rock itself if it was porous. Such plants would probably produce long lightweight stems that hung downward full of leaves. Any substantial weight might over stress their tenuous hold to the ceiling. One other possibility depending on the toxicity of the sea and the height of the cave would be for the plants to grow down from the ceiling until reaching the surface and then create some form of gas bladder (like some seaweed) or a wooden floating platform just below the surface. This could help stabilise the trunk by supporting some of the weight and allow it to grow to a greater diameter. Branches with leaves could then grow out all around the sides of this trunk. One problem would be the constant rain of debris from dead bits of plant to crumbling fragments of cave wall that fell to the water and sank to the unobtainium shell obscuring the light source. This might be solved if the unobtainium was sloped into ridges. These would tend to collect the debris. Another option would be some form of heat driven circulation that swept those debris away. [Answer] Could the root system be extremely extensive? An ancient root system through the rock face that could have eaten through aquifers (assuming that, like on earth, there can be water pockets in rock formations) and eventually, these roots extended down to the source. Maybe the roots even appear on the sea floor and grow like seaweed. Since this is right at the firmament, maybe it's these that really get the majority of sunlight, and the trees you see at the top of the cave are merely for reproduction/seeding. I can imagine this could either be natural, or as you suggested could be the case, engineered by humans, as two different plant species transplanted together long ago. As for how the tree re-seeds, I imagine some kind of bird or climbing mammal eats it, makes a nest or dwelling in the rock above, where the tree grows from, and poops out the seeds there continuing the cycle. What a cool idea for a world, by the way. I'm very intrigued! [Answer] We could assume that Schistostega was down there to, and that the tree was anchored to solid rock and holding on to some dirt. Water from pools at the bottom of the cave would evaporate, drench the soil, and boom! Now you have light and water to support your trees. We could also assume that some bats lived down there and left droppings in these pools, nd yay nutrients! ]
[Question] [ I have a medieval fantasy setting where people live in a vast expanse of giant caves. The lowest level of these caves have many lakes and oceans. Through any of these bodies of water at the bottom level you can see the sun, moon, and stars, and the water has a day night cycle. The sun shines through bright enough to support a forest of plant life on the ceiling of the cave. Gravity is about 1G and points down toward the seas. Magic exists, but I'd prefer as many aspects of this to adhere to real laws of nature as possible. The water is real water. You can drink it, you can swim in it, etc. The atmosphere is breathable by humans. Is there a natural process that could create this sort of affect under the water? [![enter image description here](https://i.stack.imgur.com/T28cX.png)](https://i.stack.imgur.com/T28cX.png) [Answer] Artificial habitat Since you specify they see the sun and stars what they see must be the real space thru a window. There are many variants but the simplest would be an [O'Neill cylinder](https://en.wikipedia.org/wiki/O%27Neill_cylinder) modified to only have a single cylinder with axis of rotation perpendicular to the plane of the orbit. You can do this because the light does not come thru the center as in the usual variant so you just have a normal day-night cycle thru the transparent walls of the cylinder and you do not need to turn the cylinder towards the sun. The water on the floor would then be useful as a radiation protection. Specifically sunlight in space is unfiltered by atmosphere and is much stronger and richer in UV than is safe for life. Channelling it thru a layer of water would cut down the light level to tolerable and remove the UV and other ionizing radiation. Additionally this would cause strong convection effect on the water which would reduce the chance of nutrients "falling to the bottom". And the UV would kill algae so it cannot gunk the windows. And by covering and uncovering the windows you can control the light and temperature in a simple manner. Mirrors or insulation would allow keeping habitats warm for their orbit. All in all making the walls transparent and covered in water is surprisingly good solution to common issues with habitats. The ceiling above would be a solution to another common issue. How to retain atmosphere. A ceiling that simply traps the air has certain brutal aesthetic to it. You'd want some sort of self-repair though. While this would require more material than a simple cylinder, the extra material of the "ceilings" would double as a source of minerals for the native life. So it might not actually be extra. And the center of cylinder would be free for whatever you want. Automated maintenance systems. A city of Gods. A hyperdrive. A space port with an entire fleet of ships docked. Huge stores of various volatiles. Automated systems for replenishing those volatiles from asteroids. Whatever. [Answer] Make the bottom of the world the top of the world, the inner layer the outer layer. That is, make it a large planetoid that has a rapid spin. The spin is great enough to force everyone towards the outside. The oceans would be on the surface, and here comes the handwaving. The gravity of the planet is strong enough to keep the water on the surface from being flung off by the centripetal force. Not sure if that is at all possible, but it is a good plot device. Maybe the 'water' has a very high surface tension that keeps the 'water' wrapped around the planet. The water is 'sticky' enough to adhere to the planet surface. As the residents moved deeper underground, towards the center of the planet, the 'gravity' would actually lessen, and the 'real' gravity increase. If they go deep enough, the 'gravity' would reverse, so 'regular' gravity would pull them towards the center of the planet. When they got to the 'bottom' (the top layer) of the cave, there would be openings in the crust layer, so they would be looking at the bottom of the ocean. Again, here is where handwaving comes in. The centripetal force would keep the water from 'falling' into the cave, being 'flung out', and the surface tension/stickiness would cause it to film over the hole. If you jumped in the water, you could swim to the 'bottom' which would actually be the surface, and you risk being cast into space by the centripetal force. The opposite of 'diving into' the water, you would be 'diving out' of the water. At this point, how far up you go depends on the actual gravity and escape velocity of the planet. That is, you are flung out by the spinning, and then brought back by gravity. Everything would be a handwaved balance of forces between 'normal planetary mass gravity' and the 'centripetal force artificial gravity' of the planet spinning, adjusted as the plot demanded. A certain suspension of disbelief would be necessary, but that is what fantasy is all about. Magic if necessary but not necessarily magic. The night-day cycle could be altered from the planet spin by pointing the axis of spin towards the sun, and the 'night/day'dictated by the revolving of the planet around the sun in some weird planetary orbital configuration. That is, at the equator, the stars would be zooming across the water but the sunshine would maintain a constant brightness, at the poles they would see either space or the sun as the planet circled around the sun. It would be fantasy weirdness par excellance. [Answer] Naboo style. <https://starwars.fandom.com/wiki/Naboo_Abyss> > > The Naboo Abyss was a series of submerged, cavernous tunnels that ran > throughout the planet Naboo, reaching the surface and passing through > the world's core. A variety of creatures lived throughout the tunnels > including the opee sea killer, colo claw fish, yobshrimp and sando > aqua monster.[1] The Jedi Master Qui-Gon Jinn, his padawan Obi-Wan > Kenobi and the Gungan Jar Jar Binks traveled through the Abyss in a > Gungan bongo submarine when attempting to reach the city of Theed from > the aquatic city of Otoh Gunga.[2] > > > I was interested on recently rewatching the Phantom Menace to consider how gravity on the top of Naboo was compatible with the planet having a (monster infested) liquid core traversable via submarine. But that is how it is! And so too on your planet. On descending to the lowest level and encountering the water, you are actually encountering the bottom of the lakes on the opposite side of the planet. By the time you encounter them you are already past the planet center and on the way out the far side, because the lakes are not that deep - light can penetrate to the bottom. Were you to swim up through these lakes you would emerge on the surface of the planet on the opposite side from which you started, having gone entirely through it. Gravity might get a little wonky deep in these tunnels at the planet's core. [Answer] # Bioluminescent microfauna The waters are filled with bioluminescent lifeforms, microscopic to the eye and blooming a couple meters below the surface. This ecosystem follows a 24 hours cycle in which some very bright species of plankton gather around a shore, then spend 12 moving to the other shore (this is the "sun"). After that other species of bioluminescent plankton gather in more sparse spheres (these are the "stars"). A separate set of species may form the "Moon". You can have a different set of "sun", "moon" and "stars" in every major water body. The stars may be fixed if the plankton that are responsible for it are fixed to the bottom of the lakes. Magic can make it so that light is able to penetrate deeper into the water of your world. This way the bioluminescent plankton may be way deeper than just a couple meters. This would give off a better illusion of sun, moon and stars. ]
[Question] [ An organisation breeds surgically, virally and genetically enhanced animals called B.O.Ws (Bioweaponised Organisms of War) to bolster troop numbers and support them in the field. These B.O.Ws perform various combat roles and include the likes of lightweight bat-insect hybrids, self-camouflaging intelligent reptilian-primatial-avians, armoured theropodial crocodiles and trenchcoated supersoldiers best described as zombie T-800s. The only problem is that when any would-be handlers deploy B.O.Ws in combat, what's stopping these creatures from rampaging about and killing allies? How could one prevent such a scenario from occurring? [Answer] Pheromones. Friendly troops are sprayed with pheromones that the B.O.W. are conditioned to recognized as friendly. Whatever doesn't carry that pheromone is attacked. That's the same mechanism some insects use to determine who can freely enter their hive/nest and who will be restless attacked. Yes, before you object to it, if an enemy knows what the pheromone is, they can use it as disguise and penetrate the hive/nest. This also happens in real world. [Answer] You can also modify your troops to not emit one specific pheromone and have the B.O.Ws to attack anything that emit that pheromones. The "no odor/pheromones " strategy is used by some animals to protect the offspring so that a predator can not sniff the puppy (I remember to have seen it on some documentary but I don't remember all the details) This way you enemy cannot just drop a stink bomb on you. The only problem I see is that it the B.O.Ws somehow reach your civilian population it can attack it (since they probably have that pheromone), but this can be solved making the B.O.Ws dependents on some substance that is given only to your troops so they don't leave the battlefield (and die if they do). Moreover you can just drop some bombs with this substance on your enemy, if needed. [Answer] Have handlers Even creatures like squirrels and ravens recognise specific humans and react to them differently. Have your creature form loyal bonds with designated handlers in the army. And animals in general understand basic relationships - if they see their handler acting peacefully, they will be peaceful also. If they see someone fighting their handler, they would come to the handler's aid. Some time ago I saw a story of someone feeding a wild squirrel every day. Then being robbed while they were out, and the squirrel attacking the robber. If say every soldier was paired with at least one animal (or pack/flock of animals) as a handler, you'd have the army effectively doubled in size, while being able to control them nearly as effectively as the soldiers themselves. Use a Shibboleth Shibboleth comes from a bible story, where the word was very difficult for the enemy to pronounce properly, and so it was used as a password. It would be possible for the enemy to train to use your language and accent, but not at all easy, and hard to do so universally, especially if your language uses sounds theirs doesn't have - for example the 'r' sound is actually relatively rare, and people raised in languages without it struggle to distinguish it from other sounds. [Answer] The allies take precautions. This is an issue all the time when you have assets of different types: preventing friendly fire. How do your prevent your bombers from bombing your infantry? How to prevent cannon fire from one group from hitting another? If you deploy gas, how do you keep it from blowing back on you? The answer: try to know where your various assets are and try to make sure the ones at risk do not get hurt by other components of your forces. This would apply equally to your monsters. If you are going to send out monsters to kill, don't mix them up with humans they might mistake for targets. If you are sending out night bomber bats keep your infantry out of the area. If you have a destructive but unpredictable asset (like poison gas, or mega monster) deploy it in an area where it can rage and do minimal damage. Follow it with a force that understands how to steer clear of it if it is still raging. --- This is also better for a story or a game because it counts on the intelligence and information available to commanders as well as the abilities of NCO equivalents in the field to keep their troops from harms way. A failure of a magic talisman is not as interesting as a shouting match between a pissed off sergeant and the leader of an armored crocodile band. Plus it offers good strategy - fall back and let the opponents armored crocs advance into an area you know is going to be targeted by the bat bombers then let the opponent fight with itself. ]
[Question] [ Let's say we have fabricating machine which disassembles anything on molecular level and assembles again in different order. We know that food consists of proteins, fat, carbohydrates and vitamins. Assuming that we don't have any problem with energy source: can we fabricate any type of food from various types of junk (metal, plastic and paper) and even from dirt? [Answer] > > We know that food consists of proteins, fat, carbohydrates and vitamins > > > To a lower level, that boils down to carbon, hydrogen, oxygen, nitrogen, sulfur, calcium, potassium, phosphorus and other elements. > > Can we fabricate any type of food from various types of junk (metal, plastic and paper) and even from dirt? > > > If you take a bar of iron, you will get just iron and maybe some oxygen if it was a tad rusted. In general with metals alone you will miss most of the elements I listed above. If you take only plastic, you will get carbon, hydrogen and maybe nitrogen or oxygen, but other elements will be missing. A tad better goes with paper: being made of cellulose fibers, it allows you to get carbon, oxygen, hydrogen. Therefore if you want to make food for heterothroph beings, you are better off starting from organic wastes, since they bring a more complete set of the needed elements. Atoms have no memory of where they were before, so the food that you will make in this way, if is has the same composition, will be indistinguishable from the "true" one. To put it in another way, when farmers use manure to fertilize the ground where they grow trees and crops, the plants will use the atoms contained in the manure to make the apple or the wheat which will end up in the apple pie you are eating right now. ]
[Question] [ I'm working on a bioweapon created by an extraterrestrial agent. The being is 2.5 m tall, humanoid, digitigrade, intelligent and mostly predatory. However, it does not require water, food or oxygen to survive (let's say it is sustained by "bullshynthesis"), though it can do so to get raw materials it uses for making offensive weapons(quills, claws, etc), and hunts solely to spend excess energy and for sport. the creature has a few cemented traits, including the ability to grow and undo specific structures (such as claws, plates for teeth, extra limbs, a tail, aquatic adaptations and others). The main issue comes with three qualities: its lower jaw splits to reveal a spinneret organ, its limbs are capable of stretching to a certain degree and it can squeeze through spaces its body technically shouldn't. The being is meant to have this many traits to be able to hunt no matter the environment (I'll admit it's quite the Frankenstein of various animal traits), but I'm mostly sure this three last qualities appear not to be in line with the majority. Is there a way to get them to function properly? How could they work, if at all? --- Edit: I pretty much remade the question, after realizing I wasn't being specific enough and it sounded like just a xenomorph with some new parts stitched to it. The creature has an appearance that indicates heavy influence or theropod and avian traits in its biology. [Answer] Take a page from the human immune system: memory T cells. Humans have large numbers of memory T cells. Each produces proteins useful for fighting a specific menace. If that menace shows up, the memory T cells kick in and reproduce, giving rise to a lot of progeny that make those needed proteins. Your creature is like this except it has a lot of stem cells, each corresponding to traits in its biological repertoire. When needed, given stem cells ramp up and reproduce, their progeny moving out thru the organism to take places. Old unneeded phenotypic traits are recycled. There may be many, many more stem cells than are currently used in this incarnation as badass hunter killer. Other possible phenotypes might include meat animal, party clown, sex companion, flying transportation and so on. A good way to fight this thing would be to hijack the master switch and compel the development of unneeded phenotypic traits. Re energy: your critter has an onboard cold fusion reactor that regenerates ATP. Easy peasy, [Answer] ## Have fun with that Xenomorph. [![enter image description here](https://i.stack.imgur.com/4FwoN.png)](https://i.stack.imgur.com/4FwoN.png) What you are describing is essentially a Xenomorph from the Alien series, albeit with a few extra features. Therefore, I suggest that you take the same route as the Yautja: get some nanoprobes and use them to genetically modify an existing creature. How about humans? Humanity is already pretty overpowered with our intelligence, strength, and dexterity. Plus, we already a predator of apex predators. All in all, humanity is a pretty good. choice. Plus, since you want it to be "2.5 meters, humanoid", you won't have to redesign the basic bodyshape all that much; you could just copy and paste the genetic code for whatever you want to give it. As an extra plus, most of our genetic code is unnecessary fluff anyway, so there's plenty of room for modifications. So, to answer your question, You can have whatever want; just slightly modify a human. [Answer] Ummm... the reconfiguration of the body, shedding structures and creating others in a short span of time (creating them from air and/or incorporating elements in the immediate env). To realize something like this, one will need: 1. the application of large amount of energy - to dislodge the atoms needed for the process from their place in the substances around; and 2. capability of transporting atoms/substances from their place of "absorption" to the place of "assembly". This transport needs to happen fast and precise; and 3. capability of very precise application of the energy to coerce the substances/elements in molecular and/or composite structures appropriate to the "offensive weapon" intended All the above sound very much like "cheating entropy at great scales" - it's simply incompatible with the biochemistry** (To handwave something like this, you may use something like a bulk core of nanobots that uses anything available to build themselves "attachments" and "frames") The problem arises when you consider where that energy can come from? Clearly not from chemical processes, you can't fight chemistry with chemistry and expect to win (at best, you get a draw). I simply don't feel that you can have a diffuse/reconfigurable source of high energies which, in addition, are so stable and so controllable one can speak of "energy flow on demand without side effects". If we handwave some sort of a "mini-fusion reactor" or "hyperspace-based energy relay", it is very likely that volume and shape of that device will be strictly fixed. That "energy source device" imposes limits on shape reconfigurations - there will be a certain macroscopic limit of crevices or super-tensile-mesh density which will stop the creature. So yo may want to drop or nuance the ability of > > it can squeeze through spaces its body technically shouldn't > > > [Answer] This seems somewhat like the creature from the Alien franchise, although perhaps closer to what the conception of the creature seemed to be in the first movie. There it was described as being made largely of silicon and having a powerful acid for blood. This would seem to imply this is not a biological organism at all, or at least not in the way we think of it, but rather some sort of mechanical construct using the acid blood as an electrolyte - an organic robot if you will. Obviously this is far beyond our ability to design and build (much less create the complex "life cycle" of the movie), but the alien engineers are obviously skilled enough to use the equivalents of genetic engineering to create this artificial being. The advantage to them is the creature can carry out difficult and dangerous tasks for the creators, and the beings are (initially) self limiting, since they will eventually run out of "battery" power. Obviously, if the engineers are using real genetic engineering and allowing the creatures to undergo the equivalent of evolution, then at some point they will evolve past the limits imposed by the engineers. So treating this as some sort of biological "robot" may answer most of the stated abilities, although with our current state of knowledge, the idea of it evolving past its initial design specs cannot be ruled out. ]
[Question] [ In an alternative universe, Maxwell’s equations still apply but ferromagnetism doesn't exist. That is to say, the laws of electromagnetism are the same as in our universe, but things like iron aren’t magnetic. What form of generators could a pre-electric civilization (think USA before Edison and Westinghouse) develop to provide for the electrification of society? And, what would be the most notable differences in everyday life as compared to our modern era in this scenario? [Answer] The evolution of technology up to the industrial revolution could mostly proceed along the same lines as earth, with the exception of the magnetic compass. Early exploration of electricity was based on galvanism (as mentioned in the Bagdad Battery answer) and Triboelectric sources (amber+cat fur). The discovery of the connection between electricity and magnetism would have greatly delayed absent permanent magnets. This means there would be very little adoption of electric motors and generators since their output power and efficiency is dependent on ferromagnetism. What are termed air-core devices -- devices that use air instead of materials like iron -- would still work but would be less efficient and less powerful. I think this would mean that society would be dependent on steam power as its primary power source for much longer than our world was. Since the development of plasma physics followed the discovery of the electron — which wasn’t dependent on ferromagnetism — and the invention of electronics followed from plasma physics, I think that there would be ample pressure for electrical power sources leading to advances in battery technology and faraday disks and Van de Graff Generators. Developments in electronics lead to semiconductor technology which leads to LED and Photovoltaics. So your society ends up kind of where we are at today with solar cells and led lighting and the rest of the stuff we have today in terms of computers. And, your world might look kind of steampunk for applications we use electric motors an electric generators for. [Answer] What form of generators could a pre-electric civilization (think USA before Edison and Westinghouse) develop to provide for the electrification of society? Purely electromagnetic ones. Plenty of AC motors are built without any permanent magnets, because the rotor can be magnetized either entirely by induction, or by running current through a commutator to power magnetic coils. Similarly, a generator can have a stator composed entirely of non-ferromagnetic electromagnets. You just wire it up so that the generator's own output energizes its own stator coils. You need a tiny bit of starter current to set up a seed field before the generator becomes self-sustaining, but that's easy to provide with a chemical starter battery, or a capacitor. (Note that the Earth itself is just such a self-sustaining dynamo. The geomagnetic field is not ferromagnetic in origin, so we're all still safe from space radiation.) EDIT: A [Kelvin water dropper](https://en.wikipedia.org/wiki/Kelvin_water_dropper) generator, or other [influence machines](https://en.wikipedia.org/wiki/Wimshurst_machine) operating by electrostatic induction, might also be viable options. Unlike most static electricity generators (e.g., van de Graaf generators, such as are referenced in EDL's answer), a Kelvin water dropper doesn't have any moving solid parts or sliding contacts, which means it would require far less maintenance and could easily be scaled up to very large sizes and voltages. They would be ideal for constructing DC hydropower stations, with none of the mechanical complication of an autoinductive electromagnetic generator. Other influence machines involve moving parts, but no sliding contacts, and so would be no more problematic than normal electromagnetic induction generators. These kinds of devices, however, produce far less power than electromagnetic induction generators, so I would expect them to be rapidly superceded by autoinductive electromagnetic generators as soon as electromagnets are discovered--perhaps sticking around as an alternative to batteries or capacitors for generating the starter current. END EDIT The differences is everyday life would be minimal up until very recently. There would be no fridge magnets, and cheap mechanical speedometers for motor vehicles would be harder to design... but that's about it. The lack of ferromagnetic materials only really becomes a problem when you want to design tiny efficient DC motors. So things like cheap motorized battery-powered toys might take longer to develop, if they aren't just completely absent, and things like hard drives, floppy drives, and CD/DVD drives would be bulkier and less power efficient. Of course, magnetic compasses wouldn't work, and that would imply some major changes in the history of navigation, and thus the history of the world... but there are ways to work around that, and while it changes some people's lives significantly, and changes the broad strokes of history, it doesn't have a whole lot of direct impact on the everyday lives of most people. After all, even in later industrial times, just prior to widespread electrification, what fraction of people in urban society ever regularly made use of a compass? EDIT 2: As pointed out by Zeiss Ikon in a comment, there would be no hard disks, floppy disks, recording wire, or magnetic tape, either. Fortunately, that's not a problem for the initial development of computers--it makes developing rewritable persistent storage media harder, but there are plenty of volatile storage options, which have been used in historical devices, that do not depend on magnetism to function--things like acoustic delay line memory and triode flip-flops. [Electret](https://en.wikipedia.org/wiki/Electret)-based technologies might be developed in place of early magnetic storage systems for temporary off-line data storage; the reduced stability of electrets vs. magnets would make such technology unsuitable for archival or distribution in the manner of, e.g., floppy disks or magnetic audio tapes, but could serve as medium-term memory to reduce the need for expensive active RAM. This isn't technology that was extensively researched in our reality, so it's hard to say exactly how far it would go. Expect, however, to see a lot more usage of things like punched tape and [capacitive disks](https://en.wikipedia.org/wiki/Capacitance_Electronic_Disc) on the way to the development of optical storage. Until the advent of re-writable optical storage, home computing would lack any equivalent of our hard drives or floppy disks; anything you want to save would have to be saved immutably, and if you want to edit something, you would do so by loading the old copy, changing it in memory, and writing it to new storage. Backups become an inevitable side-effect of working with digital technology, rather than something everybody always forgets to do! And eventually, someone will develop floating-gate persistent flash storage, which is, in fact, electrostatic, rather than magnetic, in function anyway. [Answer] The Baghdad Battery is one way to electrify things a little. Though it's actual use as a battery is disputed, the utility is very plausible. Essentially, a pot made of clay or terracotta had a copper and an iron rod sticking out of each end and was then filled with some form of acid, producing a mild current. Wine or vinegar would potentially work. The Baghdad Battery's iron rod wasn't sticking out, so that casts doubt onto whether it was actually used as a battery, but if a civilization made that minor change they would have a little bit of voltage. Stack enough of them together, world wonder style, and you could easily have enough electricity to do simple things like electroplate, create a very rudimentary electromagnetic device (maybe to make a compass, assuming the planet is still polar) are shock people you don't like. Of course, such a battery has limited use, but ancient civilizations were pretty meticulous on working hard for seemingly small results. The mythbusters did a show on the Baghdad Battery which is worth checking out. Also, my description of its construction is pretty rudimentary and I'm sure there are better ones out there. [Answer] There are several ways here are some: 1 Chemical Used in batteries with compounds like sodium, chlorine and graphene and others. 2 Heat There is a way to produce electricity directly with heat it's called thermoelectricity. 3 Friction Like the balloon and a sweater. The problem with this method is how to produce electricity at industrial levels. ]
[Question] [ One trope seen in movies is mind control. This trope involves a person or thing taking over another person’s body, whilst visual or auditory cues and friends try to help the original person regain their body’s control. This trope, however, gave me a thought. How could multiple minds control a single body? Whenever we see such a thing portrayed in shows, we usually see the person usually switch in between one person or the other, and this will sometimes result in the person causing self harm in themselves. But this leads me to my question. If all of the minds and consciousness of humanity were to be suddenly placed into a single body, what would be the catastrophic fall out? [Answer] If one body housed the entire consciousness of humanity, then the other bodies would die, either starving to death or dying of thirst or by misadventure when they lost control over their original body and fell into a garbage disposal, crashed their car, plane, rocket-ship, etc. Assuming all minds had equal control over the body, I suspect that body would very quickly tear tendons, break some bones, and sprain, or worse, muscle tissue as each mind reacted to suddenly being somewhere else, being suddenly taller or shorter or thinner or fatter or younger or old enough to finally buy beer. Given the percentage of people that lose their composure at the slightest disturbance, I think the body would scream itself unconsciousness. I’ve seen it and its not pretty. Assuming when the body wakes up, those minds have gone into a form of catalepsy and are inactive. Then, I think the rest of the minds are going to start asking what is going on or what is happening. But, they’ll be doing it at the same time and in different languages. My guess is that the minds will only succeed in biting their tongue off, then drowning in their own blood. But, assuming the body lives, and the minds find some way to communicate and share the body, then they’ll first seek food, water, and shelter while the body recovers from its assorted sprains, pulls, and broken bones before they are eaten by feral cats. [Answer] The human brain has lots of unknowns, but one thing we have clear is that many neurons follow the plan of “fire when it’s neighbors collectively supply sufficient stimulus (add up the stimulus)”, with some neighbors able to add a negative stimulus (inhibition). Let’s assume this consensus pattern holds when multiple minds are in control... the body will act when the majority of minds try to perform a given action. That means autonomic systems should keep running ... our brains will all encourage heartbeat, breathing, etc, though there may be some problems if the particular body is not near the human mean. So if average human has lungs and draws X times per minute, but our new body is used to much less oxygen than that average, we might hyperventilate. But we will probably get that under control. The next challenge will be the conscious movements. Have you ever seen the website Twitch? Collectively, people try to play games by all making moves and the system plays the consensus move. It’s a mess: fun to watch sometimes. Our body will be a lot like that. Do the minds have the ability to talk to each other? If not, it’ll be very hard to coordinate activities. If yes, it’ll be very hard to coordinate activities, but it’ll get better over time. :-) You have to decide which minds can talk to which other minds or if everyone talks on a single common channel, requiring politeness of letting others talk. If it is a single channel, the human race is probably doomed because some idiot will think it is funny to yell into the channel constantly... probably millions of idiots out of humanity’s billions. But assuming they can meaningfully communicate, and assuming they all can see through the eyes simultaneously, eventually a plurality will decide to work together and will start blocking out the contradictory actions of the others. Eventually the minority will find themselves literally prisoners in their own minds, unable to act because they are never in the majority. Now the big question for you: if all humanity is in one body, who the hell are we going to breed with? It’s going to be a brief species if we don’t have a sizable population! [Answer] Without a working theory of mind (think "artificial intelligence"), we can only speculate on how this would work. But there may be an analogy that is worth considering... Imagine a modern computer network consisting of many workstations. At two (or more) of these workstations there are people sitting down, and they are antagonists with regards to each other. They wish to use the computer's automation systems to control various physical things... opening the garage doors, lowering or raising the thermostats, etc. In a normal system like the one in my hypothetical, permissions for such actions are carefully curated, likely only one or the other can change any of these. But all are knowledgeable about how the these systems work, and wish to perform the actions even if their nominal authority does not allow for such. It is plausible that one or the other can lock their opponent out of the system (temporarily or permanently) just by being the first to seize control. It is also plausible that in some or all cases, they cannot lock each other out... and when one performs an action, the other can immediately attempt to reverse it. And which scenario would win out is really down to the details of the system. The software and network architecture (does the human nervous system have a security architecture?). While the sophistication of the opponents does matter, in your more general scenario we can't assume that one human mind is better at seizing control of a human body than another. We don't know the architecture of the human nervous system well enough to tell which is which. There is the natural phenomenon of dissociative identity disorder which parallels this, but it's unclear if that only presents as multiple minds in a single body or is truly such a thing. ]
[Question] [ If humans have evolved from apes, what if another species have already evolved from humans but left the planet millions of years ago? If this is true, in the future, if humans are advanced enough to leave the planet, could apes then evolve into humans and start the process again? Surely this would only take a few million years from the date we all leave? [Answer] First of all let's clarify a misconception I perceive in your wording. Humans did not evolve from apes. Humans and apes have a common ancestor! The exact moment of separation between the two is thought to have happened somewhere around 2 millions year ago, with the appearance of [homo abilis](https://en.wikipedia.org/wiki/Homo) [![lineage of homo](https://i.stack.imgur.com/s6GVO.jpg)](https://i.stack.imgur.com/s6GVO.jpg) This said, we have been able to observe in archaeological records way past those 2 million years: we have observed dinosaurs up to 65 million years ago, we have even observed the first form of life dating back to 3.5 billion years ago. If there was a species capable of developing space travel, we would have observed its traces somewhere: depleted ore mines, leftovers, buildings are just few of the traces they could have left behind. We have been able to see copper mining during bronze age from the increase of arsenic content in the surrounding of the villages working the copper ore! So, based on our observation, there was no species like us before us. When we disappear from the planet, can another intelligent species arise? Very probably. Can this species be alike to humans? Very unlikely. Each species is the results of billions of random mutations. It would be easier to win the lottery 100 times in a row than having two independent species be exactly alike. [Answer] Evidence of our existence is irrefutable and irreversible Unfortunately, our very current-day presence would easily be detectable in the future. Even if we leave Earth, we dismantle cities somehow and let them grow over, the unfortunate thing is future archeologists will notice: * The extinction of many species at this time. Unless we somehow bring back millions of animals and plants back from the brink, this kind of thing is noticeable and any future study of the evolution of life on the planet will see a 'gap' and marked increase in extinction. * Hydrocarbons in both the atmosphere, the oceans and the ground. These are not naturally occurring, and would be noticed in any simple ice-core or rock sample. So, extending this to: can we detect an ancient lost civilisation? The answer is yes, we would have found out already as we would notice the same traits in our past. As there is no evidence of a long lost civilisation, especially one with spacefaring capability, then the conclusion is that there hasn't been one. Now, the only way around this is to somehow completely 'write over' the planet. Much like the 'Genesis Device' in Star Trek 2 - each atom on the planet is reconfigured to suit a previous age. Not saying it's impossible, but it may be possible for a civilisation several million years advanced. [Answer] ### It's possible...if said species was really good at cleaning up. We haven't found any evidence of a lost civilization before humans, and we've found plenty of traces of humans. We've also found fossil fuels left over from very early on in the planet's lifecycle, and if another species like us had arisen, they would have depleted those stores. Evidence of intelligent species creates an obvious and irreversible mark on the planet. Or at least, assuming that said intelligent species' technology never advances beyond where ours is today. And why should we make that assumption? In an effort to combat climate change, modern scientists are already looking into ways of cleaning up the atmosphere. The thing is, we've basically burned millions of years worth of fossil fuels and turned it into gases. The only way to get those gases out of the atmosphere would be...to turn them back into solids, and put them back in the ground. This would require an immense amount of energy. It would take more energy to un-burn fossil fuels than the energy we got by burning them, thanks to that pesky Second Law of Thermodynamics. But new advances in energy technology might get us access to this kind of energy - and once we do have this energy, cleaning up our mess would be a sensible thing to do with it, right? Construction technology is also growing more modular and flexible. As civilization advances, we're looking for ways to quickly set up and dismantle buildings so that cities can be redesigned as the needs of the population changes. Who knows how far this will progress in the future? Once we can build hordes of constructor and deconstructor robots creating moving cities should be simple. So let's say an ancient civilization arose, burned through fossil fuels, found a much better source of energy, and then fixed their own climate by putting those burned fossil fuels back into the ground. They assimilated their historical constructions and developed construction that could be easily dismantled using swarms of robots. At some point after this, they discovered space flight and left, leaving nothing behind. Why leave nothing behind? Who knows? Maybe it's normal for advanced civilizations to want to leave their world in pristine condition, paving the way for new intelligent species that may come after them. Maybe as their technology developed, they finally discovered the well-hidden remains of the civilization that came before them, realized that they wouldn't have existed if the prior civilization hadn't cleaned up, and demonstrated their appreciation by copying their predecessors. Maybe we'll do the same. ]
[Question] [ Assuming I have the technical means of redirecting sunlight from a position in interplanetary space (placing the mirror[s] wherever necessary), how much havoc can I wreak on the planet Venus? Of special interest to me: could I do so much damage that the beam burns away the atmosphere or causes physical damage to the structure of the planet itself? [Answer] You could disassemble Venus into her molecular components in short time. I don't know Venus's gravitational binding energy, but it should be less than Earth's since she's less massive. Let's assume Earth's: [2.49 x 1032 joules](https://en.wikipedia.org/wiki/Gravitational_binding_energy). The Sun's output is [3.86 x 1026 watts](https://www.sws.bom.gov.au/Educational/2/1/12). That means that with some very gross rounding, you could use a [Dyson sphere](https://en.wikipedia.org/wiki/Dyson_sphere) to dissolve Venus in a million seconds. That's a little less than twelve days. In between doing nothing and destroying venus you should be able to get the atmosphere so hot that individual molecules are faster than Venus's escape velocity, so yeah, you can remove the atmosphere. If your goal is to reduce the atmospheric mass to make Venus more terraformable, though, you may have to wait from millenia to millions of years for her to cool down after the feat. [Answer] How much sunlight can you focus? [Troy Rising](https://en.wikipedia.org/wiki/Troy_Rising) postulates a solar-pumped "laser" that can push nearly 2000 petawatts, which reportedly can "destroy the Earth in 6 months, the biosphere in 16 days." But that's boring. [What if we tried more power?](https://what-if.xkcd.com/imgs/a/13/laser_pointer_more_power.png) Well, XKCD [speculated](https://what-if.xkcd.com/13/) what would happen if you aimed really powerful lasers at the moon. At a "measly" 5 petawatts, the surface turns to magma. At about 2.5 yottawatts (2.5e24 watts)... well, things get interesting. At that point, "ablative armor" comes into effect in a significant way. Moreover, the ejecta effectively becomes a propulsion system that pushes the celestial body out of orbit. Luna is smaller than Venus, but that just means your, ah, "engine" has more mass to push, but also a larger "fuel tank". For perspective, that last number is about 0.5% of the sun's output. You're on your way to [Kardashev](https://en.wikipedia.org/wiki/Kardashev_scale) II, but you've still got a couple orders of magnitude to go. Pro Tip: If you want your planet to stay in place while you're obliterating it, make sure to hit it from at least two angles (the more, the better) and be careful to keep your forces from the ejecta you're producing balanced. (Note: this is true even for meteoroids, asteroids, etc., not just planets.) [Answer] Using enough sunlight, you could potentially knock Venus out of orbit (see: <https://en.wikipedia.org/wiki/Yarkovsky_effect>), even before you burn it up. If properly calculated, YOU could use it to destroy other planets by means of a planetary projectile. ]
[Question] [ Closed. This question is [off-topic](/help/closed-questions). It is not currently accepting answers. --- This question does not appear to be about worldbuilding, within the scope defined in the [help center](https://worldbuilding.stackexchange.com/help). Closed 3 years ago. [Improve this question](/posts/167942/edit) A new country is forming in northern Australia, settlement efforts have begun, hundreds of citizens are working together to build a new city. We are dominating an informational war and are slowly becoming recognised as a developing, but considered a majorly unrecognised nation or autonomous region of Australia ## How do we economically sustain ourselves & develop industry To give some context, our government is trying to develop a highly efficient digital government for the majority of our services, removing bureaucracy and reducing the need for staff and therefore large costs. Examples include: * Fully digitized licensing services * Online business registration (we want to make starting a business in our country as friendly and easy as possible.) * Building an automated taxation system * Our own digital currency and nationalised banking system * Online voting/direct democracy platform * Online medical records * Online education (for training citizens to know how to build a city, and develop industry), and later on proper universities * A better real-time budgeting system We believe we can provide cheap power, water supply and accommodation for citizens ($300 large military tents) to start off settlement, and our citizens are willing to cope with this arrangement of living for a dozen months or so. We need to quickly develop industry (refineries, construction, servicing, supermarkets, etc), build homes & infrastructure and begin exporting products and services at a competitive rate. Assume we have a few million in capital allocated for material resources (factories, equipment, raw materials) Part of our economic value can be generated from our citizen's companies which engage in global digital services such as digital marketing, website development, software and applications and other services that can be fulfilled online, and most would be willing to have this revenue taxed. Regardless, any foreign currency coming into our country will create economic value. We are willing to harvest the necessary natural resources to do this. We have very willing volunteers willing to virtually work for free to build the nation initially, and as long as their survival needs, they will be paid in our own currency later What could we do to help make us economically independent and self-sufficient? I AM NOT ASKING HOW TO BE INDEPENDENT, I AM ASKING HOW DO WE DEVELOP INDUSTRY (what sort of companies should we start with our limited capital) practical examples ## Notes [![Our claim](https://i.stack.imgur.com/iUxnO.png)](https://i.stack.imgur.com/iUxnO.png) Our claim does include some populated areas, but we are considering them Australian enclaves, and are still fully entitled to their land under our system [Answer] ## There are some big companies that do this already - BHP, Rio Tinto, FMG. They are a corporate example of what you are trying to achieve, but what you are really after is a legal example. This is harder. Mining companies already have purpose built towns in the desert, with infrastructure sometimes owned by the mining company, even on leased land (such as rail lines to ports). They prefer this to operating out of established towns and infrastructure. Independent infrastructure therefore is not much of a problem. The reason is a corporation really needs a stable framework of laws that create a stable environment to operate in. Australia already has this, and already provides major tax incentives for mining companies to do this. So for your nation to exist you do need either a really strong deficiency in laws such that it isn't beneficial to create what you want within Australia, or a really strong argument for it to be located where you want it, or both. So perhaps: * There are Australian Laws which cannot change, that prohibit the industries your describing. Actually, the recently passed [Cyber Security laws](https://www.appknox.com/blog/glance-australias-cyber-security-laws) passed by the Liberal Government (which allow the government access to any data with no privacy) may be a candidate for this, as IT industries in Australia are already up in arms about these laws, as they cannot guarantee security to their customers and must now always have a 'back door'. * These laws do need to be irreversible though - ie. A Labor government can't just rescind them. Perhaps either they have constitutional presence, or they are physically irreversible (such as infrastructure already installed). * A strong reason why infrastructure cannot be shared, perhaps security devices are present in Mainland Australia, and none in yours, so it benefits Mainland Australia to have a kind of 'buffer state'? * A strong reason why governance cannot be shared. Perhaps the Australian Mainland government needs to keep 'at arms length' the buffer state, similar to Manus island where the Government sends Asylum seekers it doesn't want so it can claim abuse on the island are 'not its problem'. It becomes politically positive for the government to have a 'scapegoat' (such as 'it's not our country, we aren't responsible for what goes on there'). [Answer] Tax haven. This is a time tested method for small countries without too much in the way of resources - Grand Cayman, Cyprus, Switzerland and Panama are all small countries which earn a living receiving the wealth of persons who live in and profit from larger established countries. You will have banks, and serve as a tax haven for the wealthy of China and the Pacific. The fact that your citizens are web developers and savvy folks means that leveraging this will be a better bet than having them fish or grow corn. The fact that somehow Australia is tolerating your presence on its island means that you benefit from the proximity of the Australian military which will cast a dim view on armed raiders coming to attack its little parasite country. Once you have this money residing with you, you can invest it as banks do. As regards groceries and services you will do what cash rich and resource poor entities do - outsource them. Bankers concentrate on banking, not manufacturing their own toilet paper. You can concentrate on your tax haven business and purchase energy, groceries and the like at marked up prices from your big neighbor Australia. Which will make you less a parasite than a renter, and might explain why Australia tolerates your country. --- If this is taking place in the world as we know it, you will of course need some sort of agreement with Australia and the native people who reside in your chosen area up front such that your protocountry is not subject to existing laws and regulations. If you are hoping to just finesse that aspect that will work as long as you are scrag-bearded separatist computer dudes living in a tent compound. If you actually start making money or breaking laws or marrying child-wives, local governmental entities will get interested and show up. [Answer] From the perspective of "country", holding sovereign right establishes each country present in the world. Two components define that. De jure, or legal, sovereignty is the theoretical right to exercise exclusive control over one's subjects. De facto, or actual, sovereignty is concerned with whether control in fact exists. This can be approached in two ways: * Does the governing power have sufficient strength (police, etc.) to compel its subjects to obey it? * Are the subjects of the governing power in the habit of obeying it? Generally, to be considered sovereign, you must obtain both de jure AND de facto control. Having one or the other alone does not a sovereign (aka country) make. > > In general, as you have outlined your society, they will all starve > rather quickly, with their hands on all that technology. > > > [Answer] # Just Cause Well, you mentioned an "information war". So I'll presume that the rest of Oz has fallen prey to the scourge of authoritarianism, enforced by a powerful propaganda machine that the autocrats use to persecute minorities and suppress dissent, while taking away freedoms. This helps motivate the "why" of a new country. # Dependence There are two ways to declare independence: the most obvious is to be so strong that nobody can challenge you. This is going to be infeasible for your ragtag band of idealists. The other way is to be so valuable to others that nobody is willing to mess with you. So instead of focusing on independence, your group should focus on dependence. They should produce such highly valued products that foreign customers will lend diplomatic cover or even military weight to protect your de facto sovereignty. Now, this is where it gets tricky. If customers believe they can just buy your companies outright and operate them under Oz law, then your new country is DOA. You need to make it clear that your employees have a fanatical belief in "New North Ozland" and will quit working before they give up on their dream of establishing a new state. If their products mediate hundreds of billions of dollars in commerce, then folks will not want that cash cow to get slaughtered. # Finding Religion You also want to prevent other companies from poaching your best people and gutting your nascent economy. This is why there needs to be a strong reason why your people are committing to an undeveloped nation-in-progress when they have the skills to go anywhere they want. The best way to do this is for your nation to be built on a set of ideals which are unmatched anywhere else, and for your founders to believe in these ideals to a near-irrational, almost religious level. It would obviously help if your group had a very charismatic leader who could embody and proselytize these values to the faithful and newcomers. They could also be enforced by new rituals, symbolism, iconography, etc. # Infiltrate Ideally, the digital products exported by your new country are sufficiently diverse that even governments wish to buy them. When you get to the point where the Oz gov't is also a customer, then you have neutralized one of the biggest threats. At that point, you just need to use good ol' lobbying to get your new legislator friends to introduce bills establishing New North Ozland as a Special Administrative Region with its own oversight and limited jurisdiction of Ozland proper. After this settles in for a decade or two, you just keep expanding the rights until eventually your country is effectively independent, without anyone really caring or disputing the legal minutia of the fact. [Answer] [![enter image description here](https://i.stack.imgur.com/usfvT.jpg)](https://i.stack.imgur.com/usfvT.jpg) > > The Northern Territory of Australia, marked in red, has vast areas of minerals such as gold, uranium, copper, nickel, iron, manganese and rare earth elements yet to be fully explored and discovered. It is very dry and could benefit hugely from a large scale irrigation program. Tourism has a fantastic future there, based around Ayers Rock (Uluru) and Darwin, where military encampments are growing. Australia-USA Alliance. (U.S. Marines, etc.) > > > --- > > Demand is insatiable in Asia for our natural resources. Why should this demand stop? Only a worldwide depression could stop this demand for natural resources to feed the monsters of Asian industry. We have lithium ore (spodumene) to feed into China's waiting lithium carbonate producing plant. (Galaxy Lithium). We have rare earth elements, manganese and nickel. Millions of tonnes of iron ore and copper and more are in the ground. We've mostly sold out or outsourced our diminishing manufacturing industries that simply cannot compete with the cheap labour competition in South East Asia. > > > Natural Resources in Australia Map, [australiasearch.net](http://australiasearch.net/map-of-australia-resources-sector-for-post-boom-wealth/) Some maps show Zinc in what would be your south west corner (other maps show nothing of interest whatsoever, throughout the entire Northern Territory, especially the most northern bit). Australia has the 'goods', they just can't competitively make anything out of them. ]
[Question] [ "The Dark Knight" is a nickname given by astronomers to the exoplanet TrES-2b, a gas giant with an albedo of one percent, blacker than paint, blacker than coal—in fact, blacker than anything on Earth! There are several reasons it is so dark. Its atmosphere is full of materials that absorb light, and it orbits its star so closely that it roasts at 2000 degrees Fahrenheit (1100 degrees Celsius), which is hot enough to melt gold. In my story, while exploring multiple alternate Earths, our space telescopes have discovered one that is even just as dark as TrES-2b. But it wasn't orbiting nearby, so it couldn't have been hot enough to absorb the heat of its sun. And atmospheric gases are similar to what our Earth's may have been like prior to the Great Oxygenation Event 2.4Ga, not at all compatible with the supposed chemistry of The Dark Knight's atmosphere. *How else can this alternate Earth be blacker than black?* [Answer] If we start with a somewhat strange planet (mostly quartz, Iron, nickel and aluminum) and give it an atmosphere of almost pure carbon monoxide and dioxide. This is highly improbable to begin with but if we give it a very strong electric field and then hit with the mother of all solar flares you just might get optically aligned carbon nanotube growth as the planet surface approaches 1100c. Optically aligned carbon nanotubes, sometimes called Vantablack, are exceptionally dark, absorbing 99.6% of light. It's a bit of a stretch though. Another alternative would be a world blanketing bed of fungi or mold with a velvet like texture. Just plain black velvet has a surprisingly low albedo, absorbing over 99% of light. This could be a fun kind of biosphere apocalypse scenario. A planet with a slowly dying star and eventually the only thing or things that can survive is a world spanning mat of knee deep, velvety fungus that's using carbon or some other incredibly dark material in an incredibly fine, dense tangle to utilize every last photon to survive. [Answer] You say this small albedo is most probably closely connected to high temperatures. "1100 degrees Celsius hot enough to melt gold" is a large underestimation. It is hot enough to melt some rocks and most metals! And together with high sun radiation and magnetic fields it is hot enough to form plasma. Plasma is a key here - it can both be a perfect mirror or a perfect absorber depending on condition and frequency of electromagnetic radiation. For example our Sun, having "plasma envelope" is also an "almost black body". And being a black body doesn't mean "pitch black". It's quite the reverse: it means - shine brightly (at least at some specter - IR, visible, X-ray, so on.) with our Sun being good example. So if we put that "Dark Knight" planet away from its star it would rise its albedo dramatically. To have such a low albedo without plasma is impossible - there is just no such material. But using some special "metamaterials" we can create the illusion of super low albedo. The metamaterials I have in mind are small glass balls (which are closely connected to cooling down plasma). They act as perfect retroreflectors - all light which is coming to that planet is reflected to its source. So sand made from these glass balls would look black if looked at from the side, but would shine brightly if we looked from the light source. Btw, we already have such situation before our own eyes: the Moon. Its surface shines brightly when the Moon is full. But its albedo drops greatly (lower than black earth) when it's a half moon. The only thing that can spoil everything - is atmosphere. For our Earth atmosphere plays a great role in its albedo. So, to summarize, you need the following to create "The Cold Dark Knight": 1. No atmosphere at all 2. Planet is made mostly of silicates (to form glass) 3. Planet is covered with a sand/gravel mix made from small (0.1 - 10 mm) nearly perfect glass balls This can be achived if the planet quite recently got away from being close from a star: 1. All its "normal" atmosphere was blown away with solar winds 2. Cooling plasma would form that "glass ball" sand (it's actually one of the technological processes to form fine glass balls for retroreflectors) 3. Asteroids and tectonics would not destroy that glass-field yet. Btw, for the last - asteroid craters would form very bright circles on that black surface. And do not look at that planet from starside: you may blind your eyes and devices. ]

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