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[Question] [ The Crabites are back, and chafing at their chains. For context, Crabites are abyssal plain-dwelling large crabs, perhaps the size of a dog. They evolved from those rarest of creatures -- hive-dwelling eusocial crustaceans. Think of a modified honeybee model; one breeding female, close kin workers, but female births are chemically suppressed or the females driven away. (Closest Earth analogue is the sponge-dwelling snapping shrimp: <https://en.wikipedia.org/wiki/Synalpheus_regalis>) They band together to gather food and defend their food-cache. So. This works great for primitive, bestial crabs, but once they evolve intelligence, issues arise. While being the chemical slave of the Queen is fine for beasts, our evolved Crabites are smart enough to resent the Queen's dominance. Yet they still love her. The females love the Queen, and don't want to be driven away. At the same time, they want to leave, preferably taking some of the males with them to found a new hive. The males resent being "just one in the pile" of males. They want to run off with a young queen to found a new hive, where they'll be a big fish in a little pond. And yet ... leave the Queen? And take the risk of starting a new hive without the mighty food caches, and herds of sea cucumbers owned by their existing home? So ... our Crabites live their lives torn by conflicting urges of loyalty and betrayal. Their hormonal love of their Queens always at war with their selfish ambitions. Here's the question: Is there room for intelligence here? Can hive creatures develop non-hive minds and live in chemical slavery without going mad from contrary impulses? Or must I devolve my beloved Crabites into old-fashioned, boring telepathic hive-minds? [Answer] Being happy is slavery? Humans have family structures enforced with hormonal systems. We are still usually considered intelligent although how much that is true and how much sheer hubris is debatable. People will also generally not resent having a happy family life despite that severely limiting their freedom. I think you should use the ways humans deal with the conflict between family and individual ambition as a model for your Crabites dealing with Hive-Individual conflict. If nothing else using a massive free supply of base material saves lots of work. Also for the Crabites the hive and the queen would be normal. They'd have people who withdraw from them to think clearer just like we have. But most would pursue their happiness within the norms of the hive just as we do with our social structures. Humans or Crabites do not simply have the time to challenge every limitation on their lives. Usually people will focus on the ones making them unhappy and just adapt to the ones making them happy. [Answer] Reading about the Crabites, there are some frame-shift answers which come to mind: * Intelligence and the desire for independence do not always go hand in hand. In fact, a creature's intelligence may help them recognize that they have better chances of survival as a member of a society, even if it is in a subservient roll. * These are crustaceans and their desires and goals may not mirror our own. Individual ambition? How abominable! The poor queen would be left all alone if we go! Self-fulfillment may be found in serving the Queen. Even if the Crabites have the desires to run off and start a new hive, there are some approaches: * The queen can only control so many through hormones. Young queens could be used to help control larger populations, and oversee specific areas of the hive. Queen-born males and females could assume the role of the core government, who then go on to govern specific areas or aspects of non-queen born life. Yes, this is fodder for a brutal caste system, but it can work. * Male and Female Crabites must simply be conflicted, and will always be evaluating their options. Stay at home where things are secure, or move out to seek fame and fortune? That previous sentence could easily apply to many humans! Do I stay in this country, at this job, or try for something else? [Answer] In many eusocial insects, the females are all sisters or daughters of the Queen, so their social role is genetically enforced as family members. The desire to branch off is countered by a hugely amplified version of "well who's going look after mom?", followed by an equally strong urge to look after the younger sisters in the hive. For intelligent hive creatures this could also be amplified by versions of matrilineal inheritance laws; splitting off from the "family" means you lose access to the family resources, and considering the environment is rather resource limited, this would be an enormous incentive to stay (or disincentive to leave). OTOH, this would lead to genetic stagnation or even inbreeding if the males were all from the same family, so perhaps some sort of arrangement similar to lion prides or baboon troops, where males are generally tolerated until they reach sexual maturity, whereupon they are either driven off or get an urge to wander to new territories, where they can "prove their worth" and start new prides or troops (or kill the old male and take over an existing one). Since the Crabites are more similar to eusocial insects than lions, wandering males may battle it out in front of prospective queens, and the queen selects the winner as a mate (in a civilized society, this need not be single combat, it might be somewhat amusing if the competing males need to defeat each other in a chess tournament, lighting round of Jeopardy, [cotillion](https://infogalactic.com/info/Cotillion) or build elaborate puzzles to amuse and delight the queen...). To make the genetic mix and match more sustained, males could die after mating, so the queen will have a number of partners through her life, while the hive is filled with half sisters from each generation of males. This also means that if resource pressures or other cues trigger a need to split the hive, the newly "promoted" queens are not clones of the old one. The hive workers who follow the new queen will be her sisters, so the remainder of the hive will continue to function with the rest of the workers who are not genetically bound to the departing queen. (What sort of environmental cues trigger the "promotion" of a new queen and how it is done is up to you. Bees use royal jelly, but other things are possible). Please provide a link to wherever you are publishing the stories of the Crabites, as this looks to be an interesting and amusing world. [Answer] Why don't you kill your neighbor and steal his wife if she's hot? I guess the answer is that we evolved a set of rules and behaviors (civilization, religion, morals, common decency, etc) that are advantageous to the species. There's no reason your Crabites wouldn't do that. After all, if they behaved in a way that would jeopardize their survival, evolution would sweep them under the rug. We are hive creatures in a way. Back in the day, the hive would be a village, then a city-state, or a nation. Now, consider [birds of paradise](https://www.youtube.com/watch?v=_H9TyXiXM2k). They build elaborate constructions and decorate them carefully, in order to impress the females. Just like a sports car. They do this because the females like it, so they selected for the birds who were best at it. Additionally, being able to dedicate time and energy to gathering the resources to build these nests is a demonstration that the bird has good health and fitness. The bird is so baddass that surviving is easy, it even has enough time to have a hobby in interior decoration. Sexy! So, your Crabites could have the males in a competition to see who gathers most resources, to impresses the females enough that one will choose him to create a new hive. This does not prevent teamwork: if a female needs several males to start a hive, then groups of buddies would emerge. Which one of them will provide the DNA remains to be seen, though... although it could be all of them. For example, ant queens will mate with several males and store their sperm. So among the ants in an anthill, some may have different fathers. [Answer] Your crabites are intelligent, right? Well, they could realize that the best way to ensure their survival is to be part of the society, even if it's a low role. If the crabites want to leave, well, they can't. They're not queens, after all. Only the babies fed royal jelly can leave and make a hive, or die. Of course, the babies fed royal jelly would rather go than die. They're smart enough to know this. Also, if the crabites are happy in the hive, they stay there. If the crabites are not, they go. ]
[Question] [ In television and movies we have a very familiar bridge command structure: the captain gives orders like "shields up", "fire primary weapons", or "transfer power to sublight". I think this trope was probably first established with Star Trek, but it appears in everything from Stargate to Star Wars to Battlestar Galactica. For day-to-day operations this seems fine, but in crisis situations (including but not limited to combat, disaster relief, search and rescue, etc) a starship of any appreciable size (assume crew of 200+) would need to react in a hundred different ways to a hundred different situations very quickly. Far faster than any one bridge commander, or even a group of system operators, could receive information and then issue an order in response. > > EDIT: see [this youtube video](https://www.youtube.com/watch?v=A0xZ9gE5qW8) for a good example of the trope I'm referring to. > > > So my question is this: What would be the optimum way for a starship to organize itself and its crew in a crisis situation while still maintaining a strong chain of command? For the ship in question, I'll give the following assumptions: * The crew is large, but not massive. Say, between 200 and 800 crew members. (Larger than a [Firefly](https://en.wikipedia.org/wiki/Serenity_(Firefly_vessel))/[YT-1300](http://starwars.wikia.com/wiki/YT-1300_light_freighter/Legends), but smaller than the [Executor](http://starwars.wikia.com/wiki/Executor)). * The ship is equipped for the type of crisis it is encountering and the crew is well trained in their respective roles (i.e. not a cruise ship in a combat scenario). * Communication/automation technologies within the ship's systems are about as good as they are today. So no telepathic crew network, but auto-targeting missiles/point-defense weapons are plausible. * The ship has a number of different systems, including but not limited to: + Offensive weapons + Defensive weapons + Shields + Sublight and hyperlight engines + Fighter/interceptor/smaller vessels on board and appropriate hangar + Local and hyperlight communications + Typical sci-fi sensors (scan a planet in 5 sec, can't seen in an enemy ship) + Usual internals (lights, life support, bulkheads, security, etc) [Answer] The command structure of the ship depends a great deal on what the ship is designed to do, and how many separate divisions are needed to do these tasks. A battleship has a different bridge structure than an aircraft carrier, to reflect the different roles of the ships, while a destroyer has a different bridge structure than a battleship to reflect the much smaller size and crew of the ship. Even the technology being postulated has a huge role in how the bridge is structured, the [HMS Surprise](https://infogalactic.com/info/HMS_Surprise_(novel)) (a Napoleonic era frigate) has a different bridge structure because it is a sailing ship, compared to a modern ship with an engineering division to run the power plant. (A nuclear submarine's engineering division is obviously different from a gas turbine powered Aegis cruiser). So the first thing that needs to be defined is what sort of ship is this (the class or role), and then the technology needed to do the things required to run the ship and carry out the role. A ship with a large crew could mean that there is a lot of work which cannot be automated for whatever reasons (a wooden sailing ship needs a lot of hands to set the sails), or there are a lot of different tasks (an escort carrier with a similar sized crew is divided into many divisions to both run the ship and the air wing). Once you have settled on that, then each division has an internal reporting structure, and each division has a senior officer who reports to the Captain, either directly on the bridge, or to the bridge via communications systems (having everyone on the bridge when the enemy photon torpedo comes crashing in is a bit of a difficult situation). Within the bridge crew, there are also subdivisions. The Captain is on the bridge for critical operations, but when he is otherwise occupied there is an XO, and a Chief of the Boat to report to the Captain on issues regarding training, discipline and morale of the enlisted ratings and (on modern ships) perhaps civilian advisors from the various companies who make the systems that run the ship. There are also military staff who are critical to the mission but not bridge staff, like the legal and political advisors for non military issues. There are also officers and crewmembers like the ship's Purser, Quartermaster, Chaplain and Surgeon, who have critical roles to play and would be accessible to the Captain. A realistic setting would have to split the action between the Bridge crew (on a modern warship, they would control the action below decks in the [Combat Information Centre](https://infogalactic.com/info/Operations_room) or CIC), various divisions which are separated from the Bridge and CIC for practical and safety reasons (the Engineering Division should be in a separate compartment, and an Air Wing equivalent would have several different compartments as well), and a conference room where the Captain can meet advisors during planning sessions outside of combat or sailing manoeuvres (the Captain would be on the bridge during docking or transiting through a spaceport, for example). As a writer, there is no reason not to do this, but if you are contemplating shooting this for a film, TV show, Podcast etc. you can see the time and expense for setting up sets will be much greater than "Star Trek", where everything happens in one place. [Answer] May I humbly submit that you're asking the wrong question? Tropes range from the ultra-advanced-automation of Golan Trevize's ship in Asimov's [Foundation's Edge](https://en.wikipedia.org/wiki/Foundation%27s_Edge) requiring but one person to operate the entire ship, to the half-dozen people needed to run [Enterprise NX-01](http://www.samurai-archives.com/scifi/csEnt.html), to the veritable army of people needed to run a Star Wars [imperial destroyer](http://starwars.wikia.com/wiki/Imperial_I-class_Star_Destroyer). In your universe, you need to ask the question, "why do I need human intervention?" The problem with TV tropes, etc., is that telling a great story with beautiful sets and wonderful people is far more important than reality. Asimov discareded all the people by creating direct-to-brain automation: his story was focused on the search, not the ship, and dealing with a large command structure would have distracted from the story. Star Wars wanted to present the Imperium as a large Big-Brother that overshadowed personal liberty, so it needed all the people on the bridge it could get. So, basically, if you're looking for justification, start with "how much human decision-making capacity am I willing to hand over to a computer?" If you think you can do it all with automation, you'll end up with Star Trek TOS episode, "[The Ultimate Computer](https://en.wikipedia.org/wiki/The_Ultimate_Computer)," where no one at all is needed to operate a ship. Not even a captain. [Answer] Rather than a bridge the running of a large starship will probably resemble the command centre of NASA with a multitude of console jockeys overseeing the different functions of the spacecraft. They are essentially the ship's crew and the overall supervision level of the command centre would be the bridge as such. The ultimate command and control technology for starships could be autonomous machine intelligence. This would be essentially an integrated network of computers connected to and overseen by a set of AIs. The human officers would be located in a monitoring room to ensure the starship is following orders and where they can issue orders. The monitoring room will be the bridge. The only humans on board will be the ship's officer corps and specialist personnel to assist with the starship's missions. In this case, the starship itself is the body of the crew. It is tempting to call the officers parasites living in and off the body of their starship (but that's another story). There will need to be continuous communication between the bridge officers and the starship. Depending on speed of action and the response times needed, it is possible the starship will be briefed and given its orders, in advance, about which actions to take and how to respond in a range of situations. For example, assume the starship has a jump-drive. It might be ordered to jump into a suspected hostile planetary system and if it encounters an enemy in superior numbers either evade them at sublight velocity or retreat to a safe distance with another hyperspace jump or if it encounters starships from a friendly species, advise the bridge and prepare to open communications. A smart starship might be capable of making a range of its own decisions, but like all command structures it will be answerable to its officers. In summary, a starship's bridge could be a NASA style controla nd command centre if large numbers of officers and crew are required or a small number of human officers commanding an intelligent, near-autonomous starship. ]
[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/73162/edit). Closed 6 years ago. [Improve this question](/posts/73162/edit) # Problem On Earth theocracies have been very reluctant to accept scientific progress, for instance the Catholic church, which dominated Medieval Europe, had a very hard time accepting Copernicus's, Galileo's and Kepler's theories on planetary motion, and after the Muslim conquest of Egypt, in 642 AD, caliph Omar ordered what was left of the library of Alexandria to be destroyed with the justification: > > »If those books are in agreement with the Quran, we have no need of them; and if these are opposed to the Quran, destroy them« > > > (or rather [Wikipedia](https://en.wikipedia.org/wiki/Destruction_of_the_Library_of_Alexandria#Muslim_conquest_of_Egypt "not reliable source") claims that some sources say so) Therefor I was wondering if it is possible to make a realistic timeline, in which a theocracy first comes to dominate an earth like planet, before any industrial revolution can happen, and many years later this theocracy develops a working [Alcubierre drive](https://en.wikipedia.org/wiki/Alcubierre_drive). # Assumptions ## Definition of theocracy Meriam Websters defines a theocracy to be > > government of a state by immediate divine guidance or by officials who are regarded as divinely guided > > > However I will also assume that the leaders of this hypothetical theocracy do believe in their religion (that is, the religion was not created as a hoax to fool the people). ## Definition of global dominance When I say that my hypothetical theocracy gains »global dominance« before any industrial revolution can happen, I do not mean that they have to take over the entire planet by force, I only mean that they gain such a dominant economical and political position, that no other nation on the planet has the resources to invest in scientific and technological development. The reason that i want this form of »global dominance« to be a part of this hypothetical question, is that if it was not, then the Theocracy would simply be able to steal the technology of the other civilizations on the planet. ## Developing Alcubierre Drive Firstly i must assume that the Alcubierre Drive is possible, which requires that it is possible to create and contain so called exotic matter, which is particles with negative mass and therefor negative energy – something that modern science has neither proven to be possible nor impossible. Furthermore, when i say »developing the Alcubierre drive, i also mean that this hypothetical theocracy must develop both the Alcubierre drive, all the technology and science necessary to do, and the scientific knowledge to travel through space themselves (in other words, they did not steal or receive the technology from a conveniently bypassing alien, or from other civilizations on their home planet). # Question definition To sum up: my question is what events would most realistically need to take place, in order for a theocracy to develop the Alcubierre Drive by itself, based on the previously defined assumptions. # Edit As Secespitus correctly points out, this specific question does look rather opinion based, since we (as i briefly mentioned) don't know if Alcubierre drives are possible, and what developing them will require; (that is why i made sure not to ask for any specifications of how long this timeline would take). Of course i could have simply avoided having to assume that the Alcubierre drive is possible by asking for a realistic timeline for a theocracy developing advanced technology, however I still asked about the Alcubierre drive in particular both because it would require very advanced science (including all that we know now) and will (if possible) require a lot of investments in a technology which might not work at all. Therefor this question is rather about what it would take for a theocracy to make such investments in science, rather than whether or not the Alcubierre drive is possible. [Answer] The assumption that theocracies cannot develop scientifically is false. In general, religious leaders are only opposed to scientific progress when it undermines the specific principles of that religion. The specifics will vary from one religion to the next and between various possible histories, but overall, science made great strides under both the Church and the Ottoman Empire, and research was often funded by religious authorities with the context of coming to a better understanding of God's world and generally improving the lives of people within the nation. (And making weapons to fight its enemies, of course.) The only places where there was conflict was in the specific instances where a particular scientific discovery happened to oppose principles that the particular religions considered as truth, and while these instances are often held up as examples (Galileo and Darwin being the most prominent) they are very rare. Leave out or slightly modify the conflicting scriptural verses (mostly those dealing with creation and cosmology, which are among the less important aspects of most religions), and there is no reason why they would come into conflict at all. So I would say, provided that said theocracy did not happen to follow a religion that happened to have specific fundamental beliefs that were in opposition to discovering the principles necessary to create an Alcubierre drive, they would take... exactly as long as anyone else. If they were a conquest-focused or proselytizing religion? Possibly faster, since they'd have a specific motive for wanting to spread beyond their homeworld. [Answer] Technological progress is driven from marginal investments at the technological possibilities frontier. In a theocracy as anywhere else, the key issue holding up progress is not theology but the perverse incentive systems riddling any bureaucratic organization - be it a company, a world government or a church: the people in power like the status-quo, and any change to the status-quo can become a threat to their power, so they do not have a strong incentive to take risks and try new things: > > Beware, you who seek first and final principles, for you are trampling the garden of an angry God and he awaits you just beyond the last theorem. > Sister Miriam Godwinson, "But for the Grace of God" > > > However, one can easily imagine a specialist class eventually (it could be decades, it could be millennia) emerging within the framework of the bureaucratic institution that is relatively nimble and open to new ideas: think DARPA within the US government and the Jesuits within the Catholic Church. > > The righteous need not cower before the drumbeat of human progress. Though the song of yesterday fades into the challenge of tomorrow, God still watches and judges us. Evil lurks in the datalinks as it lurked in the streets of yesteryear. But it was never the streets that were evil. > Sister Miriam Godwinson, "The Blessed Struggle" > > > Basic research could come to be seen as a religious duty -- and far greater resources could be allocated in a theocracy towards reading the "mind of God" than inside a short-term-oriented capitalist society. A cost-effective way to warp space has obvious benefits that cannot be ignored by any society with a positive growth rate forever. > > At atrociously high energy states, the properties of matter change subtly and new miracles become possible. The Plasma Accretion process is now dangerous and difficult to control, but its products will soon become commonplace in our society. > Sister Miriam Godwinson, "The Lord Works" > > > Obviously this may generate some resistance. > > And what of the immortal soul in such transactions? Can this machine transmit and reattach it as well? Or is it lost forever, leaving a soulless body to wander the world in despair? > Sister Miriam Godwinson, "We must Dissent" - Accompanies the Secret Project "Bulk Matter Transmitter" > > > Once life is confirmed to exist on other worlds, it could be considered a religious duty to spread the light of wonder to the alien heathens, or even if life is not found, colonization could be considered a religious imperative. > > Go through, my children! The time of miracles is upon us. Let us cast off sin and walk together to the Garden of the Lord. With God's mercy we shall meet again on the other side. > Sister Miriam Godwinson, "Last Testament" > > > [Answer] They can develop it in $0$ years: 1. Receive science from the future 2. Use science to build an Alcubierre driver 3. Use science to synthesize exotic matter 4. Go back in time using Alcubierre drive to step 1 and give yourself science (see <https://physics.stackexchange.com/a/247048/40394>) 5. Come back to the present 6. Enjoy your Alcubierre drive [Answer] The answer could vary a lot depending on the underlying tenets of the faith that has achieved the global theocracy. It could go from the range of likely never to as fast as an Alcubierre Drive could be built. Religions are quite capable of making rapid advances in science and technology, especially if their underlying religious beliefs require it. If they believe that space is the playground of evil and must be avoided, they will shun space exploration and never develop the drive. If they believe that investigation into physics more complicated than Newton is heresy and that quantum mechanics is a mockery of Odin's goodness and predictability they will again never develop the drive. If however they have a faith based requirement to spread the faith, that has been interpret as a god given requirement to explore and colonize space with as many humans as possible they would develop space technology as fast as possible. Another tack would be if extraterrestrial life was found, say we received a clear signal from a far away star; if the religion required that we either convert our alien brothers to the truth or destroy the blasphemous demon spawn the society would again deploy all planetary resources into research into space travel. How quickly this could be accomplished is going to be total speculation since we don't know how long it would take; for example we are only 10-20 years away from net energy fusion reactors, unfortunately it's been that way for more than 50 years. [Answer] About the same time as everyone else Contrary to popular belief religions and theocracy don't have anything against scientific Discovery and development. The only problem they have is when scientific Discovery violates their interpretation of Doctrine. Indeed some of our greatest scientists have been deeply religious. Rene Descarte, Isaac Newton even Copernicus who was imprisoned for his scientific discovery by the Catholic Church. So as long as you're theocracy doesn't find any scientific discovery to be violating of Doctrine ( or at very least if it does has skill theologians you can explain why it doesn't) then should develop at the same rate technologically as everyone else ]
[Question] [ I am trying to picture how space combat would happen with a sufficiently advanced level of technology (way beyond what we have today), and obviously defense from radiation would be a massive benefit to any vessel in space. However, these spaceships will be attacking each other with directed energy weapons, anti matter warheads, fusion bombs, radioactive shells and the like. Additional protection from radiation would be a definite advantage. From what I can gather (please correct me if I am wrong) but the best protection is to limit exposure, so reducing the time spent in the radiation and increasing the distance from the radiation source. But these forms of protection are not ideal for my purposes, especially when you have a blast of directed gamma rays focused on your position. I imagine thick layers of lead (or something similar) on the hulls of our space vessels would be sufficient to block most forms of radiation, directed or not. However powerful enough blasts of radiation caused by anti matter explosions or directed gamma rays could still cook a spaceship's crew alive even if the hull blocked 99% of the radiation. Is there any other forms of potential defense from such radiation and focused gamma rays? Even highly theoretical technology can be considered here, as my civilizations are highly advanced. Is there a form of defense I have not considered here? Or is this just a case of making the hull ridiculously thick? Or is there literally no defense against a focused beam of directed gamma rays - even for a highly advanced civilization? [Answer] Gamma radiation, much like other forms of photonics radiation, isn't charged and moves (by definition) at c, so you are not going to have a force field or "Star Trek" shield to stop a gamma ray beams. Indeed, you have the same issue with lasers or even coherent microwave beams (Masers). Reflecting or refracting high energy laser beams is problematic due to the incredible energy of each pulse (the mirror surface will be damaged and even reflecting 99% of the laser will still result in the absorption of a huge amount of heat in a small spot), and with gamma ray lasers, the problem is increased since there are no "mirrors" at that wavelength. The one possible solution I can think of is "[Metamaterials](https://infogalactic.com/info/Metamaterial)", a class of engineered materials which can refract waves in directions controlled by the designer. Theoretically, metamaterials can refract wavelengths around an object like water flowing around an object in a stream (but without leaving a wake), rendering it invisible in a particular wavelength. [![enter image description here](https://i.stack.imgur.com/hd8Ae.jpg)](https://i.stack.imgur.com/hd8Ae.jpg) Metamaterial cloak Now the real issue is how efficiently the metamaterial cloak can refract the radiation. It the material is absorbing even a small amount of radiation the heat load could damage the covering, reducing or eliminating its ability to refract that radiation. The other issue is metamaterials are "tuned" for specific wavelengths. It is theoretically possible to make a metamaterial cloak to cover a submarine and bend enemy sonar around it, or even shockwaves from earthquakes. So if you suspect an enemy spacecraft is coated in metamaterials, you could use a Free Electron Laser (FEL) and vary the wavelength at random intervals to find wavelengths the metamaterials are not covering and then damage the covering for the killing stroke. [Answer] I don't know if this is particularly plausible, but as gamma rays are a form of light, they could they be cancelled by a wave travelling 180 degrees out of phase by then. <https://physics.stackexchange.com/questions/51517/can-light-be-canceled-by-merging-with-an-inverted-wave> You could have a system like noise cancelling headphones <https://m.youtube.com/watch?v=hD2hRoB1SBw> In this case you would still need some kind of protection on your layer of light detecting and emmiting cells, to stop them being damaged, but anything further in than them might be protected. (I'm unsure where the energy would go.) Possibly a similar system could be invented causing half of the incident light to be slowed so that each pair of newly seperated waves endsup travelling 180 degrees out of phase and so cancelling, but I'm no physicist. <https://m.youtube.com/watch?v=UA1qG7Fjc2A> Probably not relevant, but interesting. There are already devices called interfereometers, I don't know if a protection system based on these could work. <https://m.youtube.com/watch?v=UA1qG7Fjc2A> [Answer] I am a huge fan of the theoretical superheavy atomic weight 300+ elements. <https://en.wikipedia.org/wiki/Island_of_stability> Instead of lead or gold or uranium shielding, your ship could have Starheart shielding made of this stuff. Denser elements should mean better radiation absorbtion. Another piece of the shielding that would be compatible with everyday osmium shielding would be a reactive component. Shielding atoms that absorb radiation get hot and risk transmitting that heat to the ship via conduction. If mixed with the shield were molecules that would volatilize when hot, tiny pieces of the shield could be exploded into the surrounding space as they heated up. In space the plume of heavy matter would still act to intercept incoming rays but now can shed heat only by thermal radiation. The increasingly hot heavy shielding matter might melt or even turn to gas but would still absorb incoming rays. An entity aware of possible radiation attacks could detonate bombs of heavy matter in advance to serve as "space mantlets", the cloud of particles attenuating subsequent radiation attacks which had to traverse the cloud. This would be especially good for a fixed planetary installation which could launch the bombs up to explode in the upper atmosphere. Maybe add some cerium and iron for pretty sparks. [Answer] The glaring exception to me is AI (Artificial Intelligence). AI as we presently conceive of it comes with it's own sensitivities (Electromagnetic Radiation will need to be blocked if computing architecture remains the same). However with significant technological advances that needn't be a factor (unless it suits your story). The key thing is, defending against radiation is because you want to protect humans. The obvious defense is to not have humans (or any weak fleshy life form) on the front-line. If you have to transport humans (or others) within your universe, perhaps they would be escorted by an AI piloted defensive fleet, that would aim to intercept combatants at a distance to defend the organic weaklings from the conflict. [Answer] Although it isn't currently possible to block 100% of the emissions of gamma rays. As a second layer it would be quite useful to use the cooling of the ships as protection, since the water helps to protect against neutron radiation. With this we could create something similar to an insulated glazing that can be filled with water during combat, to make it a barrier of radiation. (It should be in the innermost layer of the shield to prevent leakage). On the other hand could use a system similar to the decoy flare of combat aircraft, which could attract and absorb radiation. Finally, it would also be interesting to use some generator of electromagnetic fields as a shield, considering the use of advanced technology could generate an electromagnetic shield to brake particles generated by radiation. [Answer] In [a story](https://worldbuilding.stackexchange.com/questions/52675/how-to-set-the-lightsail) I’m working on, a small craft is accelarated to rendezvous with a relativistic base via an ultra intense and tight laser. No ordinary material could serve as a target without burning away, but it uses a superconductive [metamaterial](https://en.wikipedia.org/wiki/Metamaterial) tuned to be a perfect reflector for that wavelength and provide a heat sink for the reality of not quite being perfect. As defense, you need to surround yourself with a cloud that acts as a [nonlinear optical media](https://en.wikipedia.org/wiki/Nonlinear_optics). Normally it is transparent, even “cloaked” to keep your defense a secret. But passage of the gamma beam through the medium will organize and alter it, becoming opaque to that beam. Due to the intensity involved, we need to reflect most of the power. So the cloud suddenly becomes a milky white fog that disappates the tight beam by spreading it over a vast area, and reflecting most of the energy outward away from the protected center. How spread out the particles may be depends on the shield’s thickness: as long as any incoming ray is guaranteeded to be interrupted by a particle eventually. It would be especially wicked if the blocked beam’s energy could be used by the defender. So the attacker deploys a bomb-based (single shot) gamma beam weapon which he thinks is totally devistating to anything and everything, only to find the defender is not only unharmed but uses the energy to charge up his own weapons! Thinking along that metaphor of the bad guy spitting the bullet back out at you, recall experiments where a cloud of energised atoms (possibly a [BEC](https://en.wikipedia.org/wiki/Bose%E2%80%93Einstein_condensate) is used to stop a beam of light—pause and restart it! [Answer] I don't think it's a big problem. With current technology we have only one way of producing a gamma ray beam coherent enough to be of any value as a weapon: A bomb-pumped laser. The laser is destroyed in the process and it's not a shipboard weapon at all--the only way you can use it is to eject the whole device into space and put either a lot of distance or a pretty substantial shield between you and it. If you can put a substantial shield in the way then your target can do the same thing. While you could get some radiation through it wouldn't be militarily useful. Thus you are limited to shielding yourself with distance. Oops--that means you just sent a delicate and expensive device (you need a very accurate seeker and pointer on board) out into space where your opponent can pick it off with an ordinary laser before it's gotten far enough away to safely detonate. Note that such a scheme has been proposed for ballistic missile defense but there's no way it passes the practicality test even though the targets have no ability to shoot back. Thus we are left with the reality that you have some way of manipulating gamma radiation. If you can manipulate it why can't your target? The same technology should be able to construct a reasonably effective deflector. (Note that the same issue applies regardless of frequency. It's awfully hard to punch a laser through a mirror made of the same material as the mirrors in your own laser at any realistic combat range. This does not apply within atmosphere, though--the atmosphere will damage your excellent mirror.) ]
[Question] [ Is there any way to explain how did humans in my planet end up with extreme dimorphism without resorting to polygyny nor "magic"? I want men to be around 6ft (183cm) - 230 lb (105kg), while women should be around 5ft 10in (178cm) - 112 lbs (52kg). The planet is similar to earth and was colonized several generations ago. In short I want both of them t be quite tall, but men to be built for strength, while women should be very agile. [Answer] Assuming man's weight comes from muscles, since you want strength this looks like a match between Arnold Schwarzenegger 6'1" ft./ 235 lbs or Marcus Fenix from Gears of War and lingerie model Candice Swanepoel 5′ 10″ / 120 lb. [![Arnold](https://i.stack.imgur.com/Tc3G8.jpg)](https://i.stack.imgur.com/Tc3G8.jpg) Though this dimorphism is far from extreme like in angler fish it is far from normal. If your planet is a colony I suggest to use founder effect where women colonists were lingerie models while male colonists were linebackers & bodybuilders [![NFL players](https://i.stack.imgur.com/h5kND.png)](https://i.stack.imgur.com/h5kND.png) Then you only have to use some kind of selection mechanism where the slender boys & bulky girls fitness is very low. Eliminate those for few generations and evolution would do the rest. I think. [Chart source](http://deadspin.com/chart-the-height-and-weight-of-every-nfl-player-by-po-1445608274) [Answer] Hmm. "Without polygyny" is the tricky bit, since that's the primary reason male mammals & birds are bigger than females of their species. Humans dumped the biological version of polygyny in favour of pair bonding (and [corresponding reduction in infanticide](http://www.sciencemag.org/news/2013/07/monogamy-may-have-evolved-prevent-infanticide)). But we kept the size difference, probably as we evolved 'job specialisation' (say, for instance, groups of men hunt big game in endurance chases, individual women hunt small game by short chases). Birds of prey often have different sized sexes (female bigger). It's not exactly clear why, but each sex hunting a different size of prey is one suggestion why. So maybe combine the human 'job description' and the bird of prey 'niche separation'? Have a situation where the two sexes have always hunted very different prey. Women climbed trees and chased down colubus monkeys through the canopy the way modern chimps hunt - they'd need to be small and agile. Meanwhile men ran down antelopes and boar on the forest floor - they'd need to be big and burly to rugby tackle the animal to the ground and beat it to death. [Answer] If your planet has genetic engineering (which is not a big stretch because Earth is right on the cusp of designer babies) then all you need is a cultural predisposition for what the ideal male and female forms are. If parents want their male offspring to be big and strong, and they want their female offspring to be thin, athletic, and agile, then that's what they're going to choose when designing their babies. Within a couple generations, that's what they're going to look like. All you need is a culture that presents these forms of masculinity and femininity as "ideals" in popular media. In other words, you need Hollywood and popular magazines. [Answer] I would say that is not so problematic, the main issue is to find jobs/roles for men and women, that were strongly separated between them in the history of your planet and that had an important role in their lives (so it could affect their look). The height is not so different so the thing you should focus on it the weight. There are plenty of possibilities that could determine their weight and with weight strongly connected strength. Especially the strength is ability traditionally useful for men (as women were at home taking care of children), so you just need the reason for men to fight and for women to not doing such a muscle activity. --- (for example very safe caves all around the planet and less of vegetation so the women could hide, but they wouldn't be so helpful outside, and the men can be always outside trying to get something to eat.... but here I am making stuff up, there is a lot of other possibilities for you, like riding specific animals, defend some specific kind of homes or building them etc.) ]
[Question] [ If the sea levels of Earth were to suddenly rise by 49 meters, or 160.7 feet, what would the world map look like? [Answer] [floodmap.net](http://www.floodmap.net/) has a tool with quite a large range (0-800 meters). I set it to 49 meters, and got some interesting results: ### Eastern United States: [![enter image description here](https://i.stack.imgur.com/8qHLR.png)](https://i.stack.imgur.com/8qHLR.png) * Most of the Eastern Seaboard is gone, including New York, Philadelphia, Washington, D.C, Jacksonville, and Boston. Other cities are now on the beach or very close to the sea, susceptible to flooding. This is a huge blow to the American economy and population. * Florida is gone. Just gone. That's another population problem. * The lower Mississippi basin is also in trouble. We've lost a significant amount of arable land, and any shipping on the Mississippi needs to be redone. The Gulf Coast is now further inland, and needs restructuring. ### Western United States: [![enter image description here](https://i.stack.imgur.com/oQGpT.png)](https://i.stack.imgur.com/oQGpT.png) * Baja California begins to flood. I don't know how this will impact US-Mexico relations. * The area west of the Sierra Nevada is flooded. San Francisco, Sacramento, and Anaheim are lost, and other major California population centers are endangered. Part of Los Angeles is underwater. * The area around northwestern Washington and Oregon (not pictured) experiences problems, especially near Seattle. The area is now a bunch of small islands and peninsulas. ### Europe: [![enter image description here](https://i.stack.imgur.com/DQMnM.png)](https://i.stack.imgur.com/DQMnM.png) * Southern and eastern Britain is no more. Say goodbye to London, Southampton, Norwich, Cambridge, Cardiff, Liverpool, Glasgow, Dublin, and Belfast. Parts of Leeds, Newcastle-upon-Tyne, and Edinburgh are endangered. This destroys almost all of the government of the British Isles. * The Low Countries, Denmark, and Northern Germany are now islands, if anything. Copenhagen, Hamburg, Berlin, Amsterdam, Antwerp, Brussels, and part of Paris have been lost. This devastates the European economy and politics. * The area around Venice and Northern Italy is covered. Most of the rest of the Mediterranean does well, with the exception of northern Egypt. ### East Asia: [![enter image description here](https://i.stack.imgur.com/o11Hk.png)](https://i.stack.imgur.com/o11Hk.png) * Most of eastern China is gone. That's a huge population loss, and a major industrial and economic problem. Too many major cities to count have been covered. * Tokyo, Pyongyang and Seoul are gone. That hurts Japan and the Koreas. * Southeast Asia, too (not pictured) also takes a beating. Vietnam, Cambodia, and Indonesia lose sizable fractions of their entire countries. ### South America: [![enter image description here](https://i.stack.imgur.com/zQCNW.png)](https://i.stack.imgur.com/zQCNW.png) * As you might have predicted, the Amazon Basin is flooded. * Most of the northeastern coast of the continent is now underwater. * The Andes protect the western coast fairly well. --- There are some overarching problems here, as you can no doubt see. * Many cities are built near water. This allows for easy trade, which was necessary for many economies before the advent of easier transportation methods, such as efficient overland travel or aircraft. However, this also means that the cities will be some of the first to go when water levels rise. * Rivers are also spots of trouble. One issue during [Hurricane Katrina](https://en.wikipedia.org/wiki/Hurricane_Katrina) was that many riverside settlements were protected only by [levees](https://en.wikipedia.org/wiki/Levee), which can only handle so much flooding. In this case, the Mississippi floods catastrophically, as does the Amazon. The Thames and the Seine rise, hurting London and Paris, respectively - on a smaller scale but hitting large population centers. * Evacuations can only help so many people. I'm not sure what the warning time is for the sea level rise here. However, you cannot easily evacuate millions and millions and millions of people with only a short amount of notice. Those at the bottom tip of Florida, for instance, would either need to drive all the way up to Georgia or try to evacuate via boat - and the latter doesn't seem great on large scales. [Answer] There are maps which shows this, for example [this map](http://geology.com/sea-level-rise/) shows scenarios from 1 to 60 meters. ]
[Question] [ Is it reasonable for a river to be shallow enough to ford in one location, while nearby (say within 5 miles or less), be at least 12 feet (3.6m) deep? The same river can have shallow sections and deeper sections, right? The reason I need it to be [that deep](https://physics.stackexchange.com/questions/146010/platform-diving-how-deep-does-one-go-into-the-water) is because, in the fantasy novel I'm working on, there is a scene where a character jumps in from a partially collapsed bridge. Because the bridge is collapsed, the nearby town can only be reached via the ford. If it matters, this is in hilly territory, i.e. the foothills of a mountain range. [Answer] It's certainly possible, as long as you allow the width of the river and/or the speed of the river to vary appropriately. Let's say the deep portion is 10 feet deep and 10 yards across. Then the area across the river is 300 square feet. Since water is incompressible, the flow through any area of the river must be constant. So, if the river widens out to 100 yards, the depth must be 1 foot deep for the same flow rate. And anything in between will do. For instance, if the river is running at 1 mph at your shallows, for a narrow section, say, 5 yards across and 5 feet deep (area is 75 square feet) the flow rate must be 4 mph. So you can mix fast, narrow and deep as you like, as long as you keep the overall flow rate the same. [Answer] Yes, absolutely There is no problem in that, in 5 miles a river can completely change. The depth of a river depends of how fast the river is , and the composition of the ground, both things can change rapidly in no time. ]
[Question] [ In my science fiction story, there are basically two nations that hate each other. There are no contacts between them and they hardly know how life is on the other side of the border. The protagonist is a young woman who has a twin brother that lives in the other nation. They were separated at birth; they know about each other's existence but they were brought up not to care a lot about it. Of course, a crucial part of my story requires them to meet. The "government" of both nations would not like it, so there needs to be a very important reason that will convince somebody to help make it happen. The best idea I can come up with at the moment is a particular genetic disease in the protagonist, that can be cured only with the help of a very close relative. The details about the healing process can be science-fictional, but I would like the disease to be something that exists in real life. Can anybody with a better medical knowledge than mine help? Edit: I doubt it adds to the question, but since some of you have shown interest, I'll explain very briefly: the two nations are gender based, women on one side and men on the other. Interaction is limited to what is necessary to perpetuate the species... Baby boys are sent on the other side right after birth. [Answer] Organ donation, blood donation and bone marrow donation. Your best bet based on existing medicine would be to have one of them desperately need an organ donation. Make the 2 of them descend from a very small minority group and note that they have very rare/unusual tissue/blood types. In that case a close family member like a fraternal twin would be fairly good bet for a match. I'm not currently aware of any genetic disease with the characteristics you describe. [Answer] What about a particular kind of cancer? I'm not a doctor, but it is my understanding that [some kinds of cancer happen due to DNA damage](https://en.wikipedia.org/wiki/Direct_DNA_damage). What would happen if the two nations had a problem on vast scale of people having these kinds of illnesses? I think they might try procedures to repair the DNA, and since [identical twins have the same DNA](http://scienceline.ucsb.edu/getkey.php?key=244), they could lead their trials on twins. Of course, if the phaenomenon is widespread, the governments would have to "use" all the twins possible (since they are rare)... [Answer] # The Re-Unification Project Your two nations have — like Sweden — a complete blood sample registry of everyone born in that country. In this setting we can even expand it a bit to have anyone ever received medical treatment in any of these countries are in the records of the respective countries. Originally this sampling was done for research purposes... but then people started taking it further. After a few couple of cases — celebrated in the rest of the world as heart-warming story of re-unification — where siblings or other relatives have reunited, for instance during majors sports events like the Olympics, a computer enthusiast group (that-is-totally-not-Anonymous), have started up The Re-Unification Project. They break into the medical registers of these two nations and copies all the DNA profiles that have been gathered from the blood samples. (\) Once they start matching up DNA profiles it is only a short while before people across the border start getting messages of the sort "Did you know you have a brother/sister/father/mother on the other side?". (\) The fact that profiling has taken place is you can make a side-story of, or even have The Project be an off-shoot of discovering that the nations have been profiling the blood samples, which they were not supposed to do. In real life, profiling is something that is a hotly debated matter in Sweden, where I am lending this idea of a national blood sample database from. [Answer] Two nations that hate each other will always have spies working in the opposing nation. One of the spies could be one of the twins or be a close acquaintance of one of them. The other one could have access to a medical facility. ]
[Question] [ In the Animorphs series K.A. Applegate mentions: > > A quantum virus. It breaks down the very forces that holds subatomic particles together. It can take weeks or even months of agony as your body grows weaker and weaker and breaks down into the fundamental particles... > > > So is it possible for such a virus to exist also what kind of gruesome effect will it have as your body grows weaker and ultimately breaks down to fundamental particles. Bonus if horrible agony can be evolved to the highest possible extent. Also for the sake of simplicity assume that the virus breaks down both the strong and weak nuclear forces. Edit: In the series Applegate writes that the virus is a disease in space time implying that is not a living being or anything we know of nor will we ever know about in the near future. However (for further simplicity) we can assume that the virus is non-reproductive entity but immortal except if treated with the correct medicine which is not available at present to the victims. Also the virus works by contact which means that if your hand comes into contact with the viruses it is the first organ to be doomed and then slowly the rest of your body [Answer] As you can gather from other answers already given here: * Your "virus" wouldn't be a biological construct; * It would be orders of magnitude smaller than a proper virus. I should mention then something called a [strangelet](https://en.wikipedia.org/wiki/Strangelet). Now there is a lot of physics to this beast, but TL;DR: * This is a thing made of quarks, just like protons and neutrons; * Protons and neutrons are nuclear matter. Strangelets, on the other hand, are [strange matter](https://en.wikipedia.org/wiki/Strange_matter) (particle physicists come up with the best terms ever); * A strangelet should be at least as big as an atom, but here's the cool thing: if the current model for them is right, they grow like [katamaris](https://en.wikipedia.org/wiki/Katamari_Damacy)! From the [wiki](https://en.wikipedia.org/wiki/Strangelet#Dangers): > > If the strange matter hypothesis is correct and its surface tension is larger than the aforementioned critical value, then a larger strangelet would be more stable than a smaller one. One speculation that has resulted from the idea is that a strangelet coming into contact with a lump of ordinary matter could convert the ordinary matter to strange matter. This "ice-nine"-like disaster scenario is as follows: one strangelet hits a nucleus, catalyzing its immediate conversion to strange matter. This liberates energy, producing a larger, more stable strangelet, which in turn hits another nucleus, catalyzing its conversion to strange matter. In the end, all the nuclei of all the atoms of Earth are converted, and Earth is reduced to a hot, large lump of strange matter. > > > What I could not find anywhere is the rate at which a strangelet would grow and convert nuclear matter. Since this is all hypothetical and you are going into sci-fi, you could use strangelets for inspiration. It goes like this: someone touches a strangelet somehow, and now their body is slowly but surely coming apart. Let's say that it would take ten years for the whole body of an adult to be converted into a strangelet... This is so slow, that the body may somehow "excrete" or otherwise get rid of part of the strangelets, and rebuild some parts of it somehow... But the person would be afflicted by symptoms not unlike those of cancer/acute radiation syndrome and leprosy, with the body destroying itself from inside out. As a bonus: a strangelet will affect any nuclear matter, not just living matter... So your patients would have a more extreme version of the midas touch. Anything that comes in contact with them, even the very air they breath, is doomed to slow destruction. Just imagine. Someone afflicted with strangeletitis sets foot on a planet. That planet may last for millenia or even millions of years, but everything in it will be converted to plasma as the eons pass as surely as two plus two equals four. This also makes this "disease" the most contagious thing in the universe. It is the very matter of the cosmos that is getting sick. The only way to prevent spread is throwing whatever planet is showing any case of this into a black hole. [Answer] # If you invoke magic, yes. Otherwise, no. If you invoke magic, then yes, such a thing can exist. If you stick with known science, no. There are no known physics or even theories that spontaneously can make the Strong or Weak forces shrug their shoulders and say "Naw, I quit... this is no fun now". So you will have to invoke magic here. If you do that, your "disease" could credibly act pretty much as severe [acute radiation syndrome](https://en.wikipedia.org/wiki/Acute_radiation_syndrome). What this means is that it breaks DNA apart which in turn means that the cells of the body stops working, unable to divide and replenish. This means that your body gradually break down over a few days, starting with the gastrointestinal tract. For a graphic account of how this happens, read about the "[Demon Core](https://en.wikipedia.org/wiki/Demon_core)" that killed physicists Louis Slotin and Harry Daghlian. [Answer] A biological virus is a string of RNA in a protein shell, that attached itself to host DNA in order to propagate. This makes it the size of a molecule, with all the physical and chemical limitations therein. An atom is a couple of orders of magnitude smaller than a molecule; the nucleus is about 5 orders smaller still. At the quantum level, an object is on the level of being detected only as a statistical probability. Your virus would have to knowingly manipulate forces that it cannot reasonably measure, while ensuring it itself is not negatively affected; an atom is an atom, after all, and your virus contains several thousand. There's easier ways to make a living than as a microscopic quantum physicist (you can't even apply for research grants ;P). Given that evolution follows the path of least resistance, your quantum virus is unlikely to exist as a biological organism. [Answer] If such a virus does exist, the universe as we know it would be gone within a few hundreds of millions of years or so. Working at such small levels, the virus would not make any difference between a living body or a stone or magma. It will simply go on working as a slow hydrogen bomb (yes, when you split atomic particles apart, you are actually converting part of the mass into energy. this energy comes from the strong nuclear force which provides some of the mass in the atomic nuclei. and that is precisely what nuclear bombs do). And as a virus, it will generate at least tens (and a nuclear scientist would wager in favor of billions) of copies of itself from each atom it destroys. Depending on your whim, the virus could travel from one place to another at the speed of light, or more horrible yet, through quantum entanglement. Farewell to the universe as we know it ... Oh, and it would be a horror to watch planets, moons, stars, solar systems, and in fact whole galaxies exploding to pieces as quintillions upon quintillions of such virus produce incomprehensible amount of heat as they take apart countless atoms in those heavenly bodies. I would desire to be long dead before that. It would be a mortally horrific sight ... ]
[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/45896/edit). Closed 7 years ago. [Improve this question](/posts/45896/edit) I'm not sure how to word this quite yet so bear with me: Let's say a group of people want to revert back to an agrarian society, but want to take with them some modern innovations that would be helpful to them in ways historical agrarian societies, like those found in feudal Europe, didn't have the benefit of using. Or maybe there is even a group of time-travelers introducing said concepts to an ancient agrarian culture that they could easily reproduce in their time (whatever helps you get into this idea). What would be good things to take with them or introduce to this society that they could readily reproduce with the available resources? Let me set some parameters: in this scenario, much of modern technology is left behind. Let's just go ahead and get rid of anything even remotely resembling a computer or a cell-phone. Nothing like that will make the transition. The same goes for cars and most major forms of transportation. Maybe even nothing so advanced as a bicycle. Basically anything after the Industrial Revolution. Anything that can be readily lumped into this pile should be; unless it can't be helped for the sake of argument, I'd like to not resort to using anything like this. But...say...they were to bring along some of the ideas we've since been able to implement into building cob or rammed-earth houses? Sun ovens or rocket-stoves? Natural below-ground refrigeration or pot fridges? Practical means of rainwater capture? Composting toilets? Biosand water filters? Greenhouses? Things of that nature. I guess you could consider them low-tech innovations, stuff that might be eco-friendly and/or present in helping developing countries have better quality of life without the need of money or advanced technology. Or, say, just simple and intelligent tweaks and redesigns to existing technology that makes it more useful, but in low-tech ways? Like, smart storage designs to maximize small spaces? Tools that can do more than one thing? Improved weapon design? Or maybe innovations in how we do certain things? Like...what things have we done in the realm of growing crops that could help a culture like this? Or raising livestock? Hunting and gathering in general? Basically anything we've learned in the resulting centuries that would have been useful - and doable - in those times. I guess I have to ask the question of whether or not some modern-day conveniences could be replicated through almost anachronistic means in this type of society...like, say, running water and a plumbing system of some kind? I know that the Romans had some sort of system approximating this, and I believe other civilizations did too (unless I'm remembering wrong). Would there be other similar ways to replicate or approximate these things? And what would they be? I'm not sure how much of our modern world, or what facets of it, can be taken advantage of in this context. So I'm throwing a wide net, and hoping people smarter than myself can fill in any blanks. And I would very much like to know how you think a society like this would come to look like and function. [Answer] Depends on how far back you are talking about going. In your question you say feudal Europe, but you also mention ancient agrarian societies. And even in that regard, there are differences in the levels of knowledge of different groups in the same time period. So I think you would get better answers if you specified. That being said there are some things that would be better across the board: Sanitation: Teaching the basics of sanitation can help ensure the population lives longer, and more hands around harvest time is always a plus. Herbalism: Now granted most agrarian societies already use plants for treating diseases, but with today's medical knowledge you know which plants are actually useful for treating what diseases. Information like the bark of the cinchona tree can be used for treating Malaria can save lives, and is something used today (the bark contains quinine). Printing Press: Knowledge is power, and being able to share that knowledge, and make sure it is passed on is a huge boon to any society. But before the printing press it was a laborious and expensive process to create copies of things. With the knowledge of how a press works, one could easily be made out of wood and stone at a much earlier point in history. With an easy way to print knowledge, it makes more sense for more people to learn to read. With more people learning about basic concepts, new ideas based on those concepts can be thought of, recorded, and passed on. [Answer] The real benefit of modern knowledge would be in the medical field. Understanding how to sanitize wounds and treat disease would greatly reduce mortality and improve overall lifespan and health. More people would survive to adulthood and live longer, more productive lives. The same is true for understanding of science (the scientific method) and value of knowledge. Besides just technology, a lot of our development in the last few centuries has revolved around our understanding of ourselves and our universe. In terms of modern things that don't involve direct technology, I would say some modern strains of crops might be highly useful. You can exclude things that require specific herbicides or pesticides (as many do) but things like Dwarf Wheat would make growing food in areas ill suited for it easier (though a lot of modern crossbreeds require herbicides and pesticides). There are also drought resistant seeds that have been bioengineered. Additionally, just the general improvements that have been made to seeds since the Medieval period and variety of crop types (for better nutrition) would greatly benefit such a society. The knowledge of crossbreeding strains of plants and a general understanding of genetics might also help, as a plant disease or insect could ruin even modern seeds that are resistant to many bugs and diseases. [Answer] What to take? Knowledge beats all. In addition some bits and pieces: Your first priority is safety. Otherwise the local knight will rob you blind and either make you into luckless serfs or run you off his turf. Immediate end to all nice perspectives. How to get safety? 1. Defend yourself with strong crossbows, and if the terrain permits halberds. Needed are basic metalworking and bow-making skills using either metal or composite wood and horn for the crossbow limbs. 2. Build yourself a stronghold. It should be the robber-baron type, far from any strong established kingdoms in order to ensure long-term independence. Next you want to be able to feed yourself. The middle ages were a period of regular famines. How to get food? 1. Good crop seeds. Current crops have a far greater yield than what the middle ages had. Today there are far more as well, corn and potatoes were as yet unknown in Europe. 2. Good domesticated breeds. Best have cattle, sheep, goats and chicken. And cats & dogs as well, for obvious reasons. Protection from plagues and injury will have to come from hygiene and first-aid. Your initial population will have some resistance against most, being for example descendants from black plague survivors anyway. Next you need to earn some money for creature comforts. I'd recommend glass-making and cloth-making as good options. Cloth is the original industry that generated sizeable wealth for commoners. Venetian glass is another example of an early, low-tech, high-yield industry. By this time you will need oil lamps as well. Now that you have all the necessities, the real game begins. Work the local policy and build your knowledge base. You need a real town now with guilds and a university. You are a power in the world. It is yours to sculpt into a better image. References: <http://www.historyextra.com/feature/medieval/10-dangers-medieval-period> <https://en.wikipedia.org/wiki/Broadcloth> <https://en.wikipedia.org/wiki/Venetian_glass> [Answer] 1 modern invention: The rocket stove. [Example of rocket stove](http://sustainablog.org/2011/09/how-to-build-a-rocket-stove/ "Example of rocket stove") Despite the high-tech sounding name, it's actually a very low tech invention. And despite how low tech it appears, it's a fairly recent invention. It's little more than a properly placed door and carefully placed fire bricks (or other insulating material). The advantage isn't in some high tech gadgetry, but just the physics-knowledge of building a stove correctly. Basically, the shape allows there to be very little waste heat, and directs the heat more precisely, allowing this wood-fired stove to get much hotter than a typical woodfire stove. This allows it to be used for a lot more purposes than the typical wood-fired stove. ]
[Question] [ ## Some Background The government is really, really good at catching people as we learned [here](https://worldbuilding.stackexchange.com/questions/40907/how-can-we-catch-a-teleporter) and [here](https://worldbuilding.stackexchange.com/questions/41776/how-do-we-catch-a-shape-shifter?lq=1). But as logic would dictate, there is always someone better. In this case, an invisible man. Unlike Dave or Eden, we know almost nothing about this new threat. After catching Dave and negotiating with Eden they have made the world aware that there is a third one; an invisible man named John. The united nations agree that he must be stopped, but how do you catch what you can't see? A Few Details on the invisible man * We know that he currently lives in America, though he could leave at any time. * Dave and Eden allegedly only know of John through messages they send each other, but both of them give different answers on why they send these messages. * From decoded messages, we know that Johns main motivation is a hatred and paranoia for the governments of the world. * John is your average conspiracy theorist, he stays at home, steals whatever he needs and works out who else has 'powers'. For all intents and purposes, he is the self made leader of these strange people * John does everything over the internet, but he refuses to use any website not in the deep web. * As a conspiracy theorist, he has cut off all ties with his former friends and family. * As a conspiracy theorist, he has stockpiled enough supplies to cut himself off out of human society for 5 years. * While John is invisible, the effects that he commits are not; for example, if he steals and eats an apple, people will see the apple hover and will see the apple disappear into the "air"(his stomach) The Rules * The governments best scientists have become desperate and are willing to spend whatever it takes to bring John into custody for further study. * They do not want to kill John, they just want to bring him into custody. * The solution cannot result in any human casualties. --- Using the above information how can the governments of Earth catch John? [Answer] John is the ultimate agent out there. You do not need to bring him in. All you need to do is manipulate his behaviour. Just plant the stories that you want to be known. Once the carrot is taken, reel it in. As soon as you are able to make him believe what you want, you can make him do anything. A team of the best agents, hackers and profilers should be able to do this. Plant some good stuff for him to grab. Guide him to a honey-pot with tasty titbits of intelligence. Some old dossiers like Area 51 should help building credit. Manoeuver him to a nice spot to set up a top notch secret base. It is of course pre-seeded with monitoring equipment. Now you have your shop running. John will detect, recruit and train new talents for the government to use in an ultra covert way. Looks like John will be able to run the new "No Such Agency" on a far smaller budget than regular government agencies. Pretty nice bang for your buck. Who needs a conscience? [Answer] This answer was written before John's supply stockpile was added to the question. The answer looses some of its applicability now that John doesn't have to leave his home. A quick upgrade to the nation's ATMs is all that is needed. Currently, each of those wonderful money machines has a ccd camera pointing out at the world, watching everything that goes by. It's a small stretch to imagine that a desperate government with a first world budget might have more than occasional access to the things those cameras see. Invisibility is John's greatest strength, but it is also his greatest weakness. All you need to do to catch him, is trade out those ATM cameras for hybrid devices which constantly switch back and forth between visible light and infrared. For a half-second, these new camera sample heat radiation and then for the next half-second, visible light. ...and everytime they see a man shaped blob with the infrared, but don't see it under regular light, report the sighting to your local governmental department of paranoia. Once you know what city John is operating in, it is time to upgrade all of that city's traffic cameras and police car dashcams. From there, it is only a matter of time before his current sleeping place is known. With that much information, catching him should require nothing more than sleeping gas and gas-masks with built-in infrared lenses. [Answer] ### Infiltrate whatever network John associates with. John feels he's a leader of what he believes to be some sort of political resistance. In order to do this, he has to communicate with other people. So the government needs to use [agents who join](https://en.wikipedia.org/wiki/Cass_Sunstein#.22Conspiracy_Theories.22_and_government_infiltration) that organisation, communicating with John on the Deep Web. As the agents gain John's trust, he may eventually let some piece of helpful information regarding his location slip. ### Set up Tor nodes To access the Deep Web, John is using [Tor](https://en.wikipedia.org/wiki/Tor_(anonymity_network)) (or an equivalent service.) Since those who are trying to catch him are a conglomeration of all the governments on Earth, they have a lot of resources. Anyone can set up a Tor node. Using a wide variety of covert (seemingly harmless) NGO's and philanthropic [front organizations](https://en.wikipedia.org/wiki/Front_organization), they [should set up](https://security.stackexchange.com/a/115365/105562) a number of nodes (entry, exit, all kinds) that is so large that they now (covertly) control the vast majority of Tor nodes. Having control of these nodes, they will now be able to compromise John's communications. Sooner or later, John will be routed through [nodes that are entirely controlled by the government(s)](https://www.torproject.org/docs/faq.html.en#AttacksOnOnionRouting). Using their technological expertise and massive resources, they will then be able to find his real IP and thus, his location. If he is using a normal proxy in addition to Tor, they just say John is a terrorist and get a warrant to get his IP from the proxy provider. ### Actually catching him Once you know where John lives, dispatch a special team with [infrared vision](https://en.wikipedia.org/wiki/Infrared_vision) goggles. These googles will see John based on his body temperature. You don't just burst through the door. Being aware of threats, John might have an escape plan. You need to first figure out exactly where in the house John is. To do this, you could post spies with infrared binoculars all around the house, trying to see his body heat. You could also dispatch silent drones with heat sensors to attach themselves to the walls, but this might be risky. What if John goes outside and sees one? If John is sufficiently careless, you may, even without infrared, see doors, food items, his personal possesions, etc. moving around in the air inside. Once you know where he is, you need to burst into that very room. Bring a massive "water-bomb" that gives a blast of watercolour paint, painting everything in the room, including John, red. Or you could follow the water with an explosion of flour, making everything in the room covered with flour. That should take care of his invisibility for a little while. Then, handcuff him to the inside of the car and drive off. Obviously you need to have him locked up/handcuffed for the rest of his detention. [Answer] John is no more difficult to locate than any other human since he has the same needs and wants. Any man tracker can use normal methods to fid his location. The difficulty is the final moments of apprehension since you can't see him with visible light. Agents unaware of this will be hard pressed to catch him if he attempts to flee. Agents aware of his invisibility, but unaware of how to detect him with some other method, will have to set up a shoulder-to-shoulder cordon around his location, physically block all entry/exit points, and watching out for suspicious movements of objects (curtains, windows, triplines, etc). They can still hit him with bean bag rounds, tasers, tear gas pellets, etc if they saturate any area but they have to know ahead of time to do this. If they have the means to detect him (infrared googles, sensitive microphones tracking his heartbeat, sensors that "smell" his sweat or CO2 emmisions, paint distributing munitions liberally applied, adhesive foam spray in the ground, etc) within a limited area then he can be easily corralled and captured since presumably he will not be able to interact with any object or protective device (gas mask, armored vest, firearm) without revealing himself to long distance interception (drug dart firing rifles, tasers, etc). This will all require lots of manpower, however. Aside from thermal imaging most detection methods are laborious to use, of relatively short range (FLIR can be used by drones or helicopters though), or require time to set up and deploy. John's main advantage is short term escape. His long term survival relies on his ability to network with like minded individuals, access money/supplies, and be able to blend in with everyone else. If he can't fake a physical presence he will have to do everything he needs over the phone/internet/or through a hired proxy. These methods are far more trackable than doing them in person since electronic methods can be monitored and using a proxy adds complexity and opens him up to being turned in. His SUPPORT NETWORK is his greatest vulnerability as he himself is greatly hampered due to the need to disguise himself in order to interact with ordinary people. [Answer] All the answers about tracking John by matching visible light optical with thermal or infrared is that the OP mentions "While John is invisible" which suggests he turn his invisibility on and off. If John is smart enough to walk around visible it will be difficult to spot him using comparative imagery. However, government buildings and facilities can be safeguarded against him sneaking in by using a much simpler version of this same technique. Photo-electric beams across doorways and entrances and set up in pairs with one beam visible light and the other infrared. If John blocks the infrared beam but the visible light beam passes right through this can trigger a silent alarm. As for catching him Fiksdal's infiltration of the deep net sounds like the most sensible approach. If he never comes out of his house and abjures society, but he would be dangerous if he did do so. The main problem is that he's an invisible man who, paradoxically, nobody sees. The answers that suggest he can be tracked if any other malefactor are essentially correct. Catch him through his normal needs of supplies and the communications he uses to marshal his agents. It's only the actual laying on of hands to capture him for sure that has problems since he can become invisible. Stun grenades and water colour bombs might do the trick. Disoriented by the stun grenades he might lose his invisibility, but if he was invisible the water colours might soon disappear too if he can ingest apples and have them vanish. [Answer] <https://www.youtube.com/watch?v=w-YLJ-pHRhA> It sounds really annoying, but it can give you some ideas . Like luring him into a building, then activating the fire sprinkler system and then watching a blob of water running around. [Answer] Why not attach a infrared camera, and a normal camera to a drone ? If the images don't make sense (that is, the normal camera can't see anything out of the ordinary, but the infrared camera does) then you have found your invisible man ! This will take a long time though, because if the invisible man stays inside all the time, then it will be hard to find him that way. Also finding one dude in a city is also hard (though it's made easier by the fact that he obviously wont go into crowded places - otherwise people will constantly bump into him, so they drones should focus on areas with less people). This way, you don't have to send spies or all sorts of elaborate plans, just a lot of drones. (High up, so he wont realise there are tons of flying machines in the sky) ]
[Question] [ Grab the popcorn ladies and gents, I'm gonna talk about a movie real quick. In the movie Total Recall (2012), the main character and his friend step into a huge earth elevator/public transportation system that zooms them through the Earth's interior. We can assume that the elevator went straight through the core and out the other side. During the ride, they seemed perfectly comfortable and really relaxed, which shows that the environment they were in was controlled (and there wasn't much turbulence/"shaky-shaky"). Now the question: What are the consequences of doing this? I know that the removal of the core is a pretty gigantic task by itself, but also combatting the temperatures itself would be enough to make most engineers walk away. 1) Can we emulate/imitate the presence of a core (to preserve magnetic fields, etc...) 2) What systems could we use the combat the temperatures? 3) How advanced of a society would we have to be to be able to make this? [Answer] All sane engineers would walk away unless they are paid by the hour without penalty for failure and they have ethics of [Wally](https://en.wikipedia.org/wiki/Wally_%28Dilbert%29) because it is far beyond engineering and science that we know. 1) You mention removing the core -- this is even way more insane than drilling through the core. 2) How would you combat the temperature? No material can survive the temperatures required. The wall of the tunnel will melt or vaporize. You can't even cool the walls because part of the tunnel would necessarily be in contact with the core (and under extreme pressures - up to 3.6 million atmospheres) so even running liquid helium through the tunnels walls would not prevent its failure. BTW, the tiniest leak would result in explosively filling the tunnel with magma, molten iron, etc. Casualty insurance premiums are going to be very pricey indeed. If the tunnel were in a vacuum so that no heat was conducted into the train, it would still be nearly impossible to keep the train cool because of the high rate of heat transfer from infrared and visible light radiation as the interior temperature is expected to reach almost the same as the surface of the sun. 3) How advanced would you need to be to make this work? You would have to have force fields far in advance of star trek. We don't even have a working theory as to any physics that would allow for force fields. You need brand new physics. I.e., you need tech that seems like magic to us. --- Assuming no friction, for the entire 38 minute duration of your trip, you are in free fall. You accelerate down until you reach the center at max. velocity of 28,440 kph and you start decelerating until reach the surface at zero velocity. At the exact center there is no acceleration and you are in a micro-gravity environment, i.e., your head would experience a small tidal force (a few milli-Newtons) pulling it down and your feet would experience a pull in the opposite direction but your net acceleration would be zero. Of course, no matter where you are in the vicinity of the Earth you experience similar tidal forces. A final complication, antipodal locations are relatively rare that have land on each [antipode.](https://en.wikipedia.org/wiki/Antipodes) Only 4 percent of the earth surface terminates at land on each end. For example, Africa has no land mass at the antipodal locations except for some Pacific islands. Europe, basically nothing but a small fraction of France that has New Zealand as an antipode. For a minimal comparison, consider the complexity of actually drilling the train tunnel under the Swiss Alps - recently completed and expected to open for service in 2016. Watch the [video.](https://www.youtube.com/watch?v=QaTN_R1b00I) This is nearly state of art drilling without the complications of the temperature and pressure you will encounter in a gravity train tunnel. Sorry about the annoying dramatics on the video, could not find a straight up quality documentary. I am also reminded that the [Alaskan Way Viaduct](https://en.wikipedia.org/wiki/Alaskan_Way_Viaduct_replacement_tunnel) has been very troubled (broken down digging machine). Digging tunnels is hard, even close to the surface. Other than the fact that it is totally impossible for the foreseeable future, it would be a very interesting and efficient ride. --- [This article has nice explanation of the actual fall including the Coriolis effect](http://www.askamathematician.com/2012/08/q-if-you-could-drill-a-tunnel-through-the-whole-planet-and-then-jumped-down-this-tunnel-how-would-you-fall/%0A) that I neglected when describing the trip as free fall. @lorenpetch noted the omission. The full truth is that I am not 100% certain of the real effect. Nearly all articles that refer to gravity trains simply refer to it as free fall, but I am pretty sure that there should be the Coriolis issue. So, I think Wikipedia, etc. is wrong, but did not want to invest the time to prove this to myself. Any takers? If you can do this rigorously it would be real nice of you to update Wikipedia too. It seemed beyond the necessary scope of this answer so I omitted it initially. The reason I am so nearly sure is because of angular momentum; I can't see any way to explain away this problem. So, I use the dodge of lateral acceleration coming from the train track (that does not affect the vehicle speed, just its path, keeping it in a straight line). In a tunnel from pole to pole the Coriolis effect would not be an issue. Continental drift and internal flows within the Earth would certainly complicate the tunnel, making expensive maintenance on ongoing problem. [Answer] As Gary Walker said, there are not that many places that have land on a straight line tunnel that goes straight through the core. The good news is that you could go around the core by taking a [hypocycloid](https://en.wikipedia.org/wiki/Hypocycloid) path between two non-antipode points. You still have to go deep into the mantle, which is still way beyond our technology level for the foreseeable future, but it's slightly less crazy. All hypocycloid routes would take exactly the same travel time. A tunnel from France to England would have to be 55km deep, which is into the mantle. Alternative That being said, a much more feasible way to accomplish the same thing would be a space plane. The [Space Liner](https://en.wikipedia.org/wiki/SpaceLiner) concept had flight times of 90 minutes from Australia to Europe, and 60 minutes from North America to Europe. This is slower than a gravity train, but it's also possible to achieve in our lifetimes with present/near future technology. [Answer] This is preposterous :) I could see Three conditions that might, in a sci-fi realm, justify an underground "elevator" (do you even call it elevator?). 1. We are not talking about earth but about a rock in space. The rock has no atmosphere and no protection from meteors. Travelling on it or it its "skies" would be dangerous. The rock will also not have a core and will be small enough for a tunnel to be bored in a generation. 2. You are not going through the CORE of the earth but through a "chord". That chord has been naturally created by water or gas flow in hot lava and since the tunnel is already there, it might make sense to line it up and use for transport. 3. Like 2, a pre-existing chord. This time, it was not a natural phenomenon but a result of mining. We found a vain of gold, mined it, lined up rails for our mine gear, mined it, lined up rails... For a couple of decades until it was mined out - but we still had the rails in there so maybe worth to use for transport. Especially viable if there's a little left to mine here and there along the vain to justify keeping it open. ]
[Question] [ I'm interested in exploring an advanced society where electronic technology and infrastructure were not developed. What plausible natural phenomenon or context would prevent, or at least strongly discourage, the widespread utilization of electrical energy? Some possible ideas that come to my mind are disruptive magnetic fields or frequent geomagnetic storms. I'm sure there are many other possibilities as well, perhaps including aquatic civilization or inaccessibility of suitable mineral resources. Bonus points for considering: 1. Technological alternatives that might emerge more prominently in the electrical void (e.g., fluidics) 2. The phenomenon's other potential impacts on humanoid life For reference, see these two semi-related questions: * [What would be the state of society without semiconductors?](https://worldbuilding.stackexchange.com/questions/14135/what-would-be-the-state-of-society-without-semiconductors/14140#14140) * [What kind of event could stop electricity?](https://worldbuilding.stackexchange.com/questions/11189/what-kind-of-event-could-stop-electricity/11197#11197) Edit: In response to concerns about broadness, I'm happy to provide more structure to guide answers. Ideally, let's imagine a terrestrial society that develops similarly to human civilization through the dawn of electricity. Needless to say, some complications may arise from the phenomenon that curtails electrical technology. While I think this question could help other related questions, the "best" answer will be one that yields a society most similar, at least temporarily, to 19th Century Europe. [Answer] # Absence of electricity: Religion The Thunder is sacred and thou shall not harness It. It's not a far stretch - actually, it's a minimal one, considering how the huge Aztec empire did away with the wheel, an object so common and idea so trivial it's impossible it could not be invented - but being the sacred Face of the Sun, it was forbidden from such mundane use as transport. # Absence of electonics: Solar Flares [Solar storm of 1859](http://en.wikipedia.org/wiki/Solar_storm_of_1859) disrupted all electricity-based communication but didn't destroy it. > > Telegraph systems all over Europe and North America failed, in some cases giving telegraph operators electric shocks. Telegraph pylons threw sparks.[8] Some telegraph operators could continue to send and receive messages despite having disconnected their power supplies. > > > Had it happened today, most of electronics would have fried. Electron lamp based circuitry would probably survive in major part, but the computers, satellites, even airplane avionics up in the air, would have suffered greatly. If solar flares of such magnitude were a monthly occurrence, development of integrated circuit would be stopped in its tracks. We'd still have a standard circuitry with discrete transistors, but we'd never achieve the scale of miniaturization of today's computers: instead of several nanometres of raster, it would be several millimetres, a million times bigger circuits to do the same job; and top speed (currently severely crippled by speed of light) at least a million times lower too - not to mention total size restrictions - make the lines too long and the solar flares will fry them. [Answer] Absence of metals One thing that all electronics that have been developed on Earth rely on is metal conductors. What if your society didn't have access to the right materials to make these things? Your humanoids, for instance, could have evolved on giant floating islands of vegetation on the surface of a world covered with water. These islands, floating miles above the sea floor far beneath the waves, have all of the elements that humanoids need to evolve, but without any solid ground, the humanoids that evolved on them don't have any metal mines. Without metal mines, no metal. Without metal, no wires. Without wires, no electronics. It's possible, even probable, that said humanoids would one day develop technology to reach the bottom and then start developing metallurgy, but a lack of surface from which to mine metals would significantly delay the development of electronics. It may also be possible to have a planet that simply doesn't have appreciable quantities of metal, though I'm not entirely sure how such a planet could form. [Answer] > > I'm interested in exploring an advanced society where electronic technology and infrastructure were not developed. What plausible natural phenomenon or context would prevent, or at least strongly discourage, the widespread utilization of electrical energy? > > > I thought of two options immediately after this (the second is better because it fits with the fact you want the cause to be natural): * 1 - Moving backwards after devastating consequences of a technological singularity: + Example: Technology has evolved so much, robots took over and there were a lot of deaths. Humanity prevailed and has sworn never to go back that route again by forbidding anything electronics related. Everything went back to purely mechanical machines. * 2 - Not having made the technological leap in the first place: This is the better option according to what you asked in your later comments. Humans never made the jump to electronics in the first place and still lived in a 19th century setting. This can be done by thinking about the chain of events that has actually led to the advent of electronics, and breaking a link here, another there... Technology is what it is today partly because some materials violated Ohm's law, and some people noticed it: What if the semiconductor technology has never been what it is? There can be a bunch of reasons for that, but let's screw with the people side of Physics: + Antoine Becquerel died in Spain and never had his son, Edmond Becquerel (who'd never discover the photovoltaic effect, neither have his son, Henri Becquerel, who'd never work on radioactivity with the Curies). + The University of Göttingen was never built (can you imagine the dramatic effect on humanity? All the great people who'd never set foot there, or meet.) + Bernoulli never taught Euler, who'd have made great contributions to religion I suppose. But you'll have to do a lot of that.. And since technology followed a hockey stick curve (which is funny, since it's the non-linearity in semiconductors and the fact they're characterized by a hockey-stick curve that makes them interesting), the difference between 19th century Europe and the 20th century would've been marginal if we didn't hit the inflection point... Which brings me to this: You can toy with it and set History to a major fail that would have wiped clean most of the talent that was required to get to the wafer. Maybe a disturbed person put a bomb at the Solvay Conference. Can you imagine the consequences? Most of the big names would have died and we'd never have integrated circuits. If you want to go hardcore (and lamer), you can put a population terrified by science who'd try their best to sabotage any progress. You can force it by going the "What if there was no silicon in our galaxy?", but since it's one of the most abundant elements, this would be pushing too far. That's what came to my mind for now. Maybe I'll have something better [Answer] By some freak occurrence the inhabitants of your civilisation develop [EHS](http://en.wikipedia.org/wiki/Electromagnetic_hypersensitivity) or Electromagnetic Hypersensitivity. This makes them unable to work with or be near electronic devices. Being an advanced civilisation they look for and find alternatives. [Answer] Not quite an answer to your question, but perhaps close: A world without digital electronics. Give [analog computers](http://en.wikipedia.org/wiki/Analog_computer), both mechanical and electronic, a better start. Digital computers could be overshadowed in the way that [VHS defeated Betamax](http://en.wikipedia.org/wiki/Videotape_format_war). It might help if there was no world war at the time to push code-breaking applications. [Punch card machines](http://en.wikipedia.org/wiki/Unit_record_equipment) for digital sorting would remain incompatible with computers for analog calculations. ]
[Question] [ Could a shark theoretically exist at the size of a blue whale? Blue whales are apparently the largest animals to have ever existed, at 30 m long and 200 tons weight. There are many species of sharks, but I'm interested in species such as Great White sharks that are capable of attacking and feeding on large animals such as seals, squid etc. Basically I'm wondering if an animal that feeds on squid and fish could survive if it was as large as blue whale, or if only baleen animals can survive at that size. [Answer] sure. Blue whales get up to 30m long. Fiction should have no trouble reaching that size, as nature got you at least half way there. The [Megalodon](http://en.wikipedia.org/wiki/Megalodon) was estimated to be 18m long. And it's a whole lot bigger when the fisherman tells the story! [Answer] The main problem isn't the theoretical maximum size of the animal (as hinted already, that can be achieved in earth gravity). It's keeping the animal in food. A blue whale is a slow filter feeder, gulping up tons of plankton while slowly swimming through the water. Sharks are active hunters, would need very large prey items if they get that large. And that means an entire population of megafauna in the oceans. Such of course existed at the time of megalodon. And that one died out when the saurians it preyed on died out. So your ecosystem would have to be such that megafauna exists, and has the plant and animal life for it to feed on, in order to sustain the shark population. The few blue whales (and other large whales) in our oceans will probably not do, they're too few and far between to provide reliable sources of sustenance to a viable population of megasharks. [Answer] There would have to be a reason for a shark to get to that size, but there isn't one on Earth today. Sharks are successful hunters, and thrive at their current sizes unless impacted by change in climate and human intervention. So, if you place a large number of extraordinarily sized prey (or large volumes that require a large mouth), then it would make sense to me to have a large predator like a shark. [Answer] There are things like the megamouth shark today. Cetations evolved filter feeding from the same ancestors as toothed whales. You just need to find a tissue that can be deployed for the purpose. Mammals don't have gills anymore so there are "gill arch" structures that can be reused. Fish already transformed some gill arches into jaws and ears. Some fish have a second set of jaws in the throat, so that suggests something that could turn into a filter. Then you need adaptive radiation to promote rapid evolution. A completely new environment or other major factor that affects the lifestyle would allow rapid transformation, as cetations did at breakneck speed (an extreme case) when they returned to the sea. Filter feeding would then promote large body growth to be more effective at it. [Answer] Yes, but there are a lot of implications with that. There is a law called the Square Cube Law that says that : When an object undergoes a proportional increase in size, its new surface area is proportional to the square of the multiplier and its new volume is proportional to the cube of the multiplier. To increase feeding space by simply scaling the creature up is super bad, and so it is restricted to its max size that which it can contain and live. If there were a huge fluctuation in large prey items, then maybe the mega shark would be feasible [Answer] Carrion eaters. [![swimming sauropods](https://i.stack.imgur.com/qAWJP.jpg)](https://i.stack.imgur.com/qAWJP.jpg) I envision a world with large herds of huge herbivores in contiguity with shark habitat - bays or estuaries. Just as carrion from land animals supports semiaquatic crocodiles, quantities of carrion from huge animals that die in the water could support scavenger sharks. The more meat you can fit in your body the longer you can go between meals and so there would be evolutionary pressure to get big enough to eat a lot at once. These things would need to be able to fight, but mostly with other scavengers interested in the carcass. Great white sharks do that today. <https://earthsky.org/earth/great-white-sharks-supplement-a-seal-diet-with-dead-whales> > > Typically, the sharks approached a dead whale slowly, swimming around > it and mouthing it at different parts of the carcass. Feeding usually > started at the extreme rear body and tail of the whale, then proceeded > to blubber-rich sections of the carcass... A shark could continue > feeding for over 6 hours, until it reached a point where it could eat > no more. As if intoxicated, the sharks could not lift their heads > above the water, while half-heartedly nudging and mouthing the > carcass, seeming too weak to bite and tear at the flesh. Eventually, > they would give up, floating to the depths. > > > [Answer] The largest sharks in the fossil and extant record are the whale shark and the Carcharocles Megalodon or "Megalodon" shark. But jaw and bone examples indicate the maximum theoretical size of a megalodon could approach 70 feet and push 120 tons. His size is solely dependent on the success of the creatures ability to feed itself. From an evolutionary biology perspective, the bigger herbivores got, the larger carnivores got. [![enter image description here](https://i.stack.imgur.com/sUxd3.png)](https://i.stack.imgur.com/sUxd3.png) [Answer] As mentioned in other answers, the size of the preator is largely determined by the size and availability of the prey. If the oceans are full of pods of whales, then an extremely large predator would become viable, since there would be a reliable supply of food. The other issue to look at is "why" a predator has to evolve to such a size. On land, mega predators arise wherever there are megafauna, such as the last ice age. Megafauna are advantaged in that environment since the square-cube law means that they have less surface area relative to their size to radiate heat, so a mammoth is much less likely to suffer hypothermia than a lemming. Since the prey animals are so large, a much larger and more agressive predator is needed to successfully hunt them, such as dire wolves, sabre tooth tigers and short faced bears. Sabre tooth tigers suggest another thing in this ecosystem. Large prey animals might need different methods to attack and kill. Biting and holding the neck to choke the prey works for a tiger to kill an antelope, but would be totally ineffective for a mammoth. Sabre tooth tigers evolved long stabbing canines to deliver deep puncture wounds that caused prey animals to bleed out. A possible analogue in your wourld would be a narwhal, although the modified tooth in that case is used to lift molousks from the sea bed. The swordfish suggests an alternative to deliver slashing blows to prey, weakening it to the point that the jaws and mouth can come into play. Other methods might suggest themselves as well. So imagining megapredators really involves thinking about how the entiire ecosystem works. why do such large prey animals exist, and how do the predators deal with them. Other questions like scavengers and parasites should also come to mind in a fully developed ecosystem. [Answer] A very large great white shark (6 m and 2,200 kg) needs to consume about [15,000 calories](https://www.sciencefocus.com/science/head-to-head-orca-vs-great-white-shark/) a day. At 30 meters in length, A great white-esque shark would weigh 715,500 kg according to the formula 0.00525[length]^3.476, or 275,000 kg if simply scaling it up. The equation used to predict a great white's weight based on its length doesn't really work at such sizes, so I will use 275,000. (275000/2200)^0.84 is 865,955.69 calories a day. That is 73 skipjack tuna, 8 yellowfin tuna, or 1 668 kg shark. Every day. [Answer] Blue whales are proof that sea life can get that big. With a little genetic tampering, there is no reason we couldn't militarise a whale into a kick-a$$ 100 foot pseudo-shark. Add teeth and abrasive skin, give it keener hunting senses and a bad attitude. Whales are already used to eating all the time, so you're halfway there. ]
[Question] [ This question was inspired by the the Fortnightly Challenge, and also a common occurrence in many fantasy novels. This question is going to use the incomes of England around 1270-1400, based from [this article](http://usna.edu/Users/history/abels/hh381/Costs%20of%20war%201200_1400.htm), for some of the prices of services and goods. We have 4 heroes. Like all so many heroes, they are on a journey. Journeys cost money, though. Our heroes were simple laborers, farmers or some such. Since their call to action was sudden, they don't have much but the clothes on their back and a few tools- 1 dagger per person, a hammer, and some spare bits of cloth and leather. These heroes need to stay at an inn. They've run into baddies, etc. and want some rest in a proper house. The innkeeper, a practical man, demands they pay for their stay, either with money or through their own sweat. The heroes currently have no money; they need to work to get a room. If there are 4 heroes, all of them being "laborers", what can they do to earn their stay? (Please provide monetary values for what they do; that way, we're sure the work they've done has covered their costs.) They must complete their labors over the course of 1 working day, or 8 hours. Any task taking longer and these heroes will not be on a journey any longer, and our tale will end with them trying to work off debt in a most un-heroic way. There are ample opportunities to practice almost any trade which falls under the category "laborer" and the locals seem willing to fairly pay them for help they offer. (Laborers can be: farmhands, (apprentice-level) smiths, (apprentice-level) weavers, fishers, lumberjacks, etc.) These 4 heroes will eat a whole chicken, a 1-pound loaf of bread, and 1 gallon of ale between the 4 of them over the course of their 1 night and morning stay. (They are thirsty!) The innkeeper also wants a profit margin of around 20%. About .1 pence for the bread, .5 pence for the chicken, and 1 pence for the gallon of ale, so about 1.6 pence total costs for the innkeeper. With the profit margin needed, that means it costs around 1.92 pence for all four of them. If this is not possible, what can they afford in terms of lodging and food? [Answer] In addition to the fact that our heroes could have looted the baddies they encountered and thus most likely do have at least a bit more of value on them... It's important to keep in mind that at this point you're discussing a barter economy. It's not merely a matter of figuring out how much coin someone could earn in 8 hours of a given labor and comparing that against the cost of a room for the night and a hot meal. A laborer might earn just half a pence for mucking out a dirty stall -- but to an innkeeper with empty rooms, even if he normally rents them out for 5 pence a night (just an arbitrary number), that day spent mucking his stalls could easily be worth letting them stay in the room. (On the other hand, if he's got a steady flow of paying customers coming into his rooms, he might not be so willing to let one go for so cheap!) The same could be said of the food -- if there's not enough customers coming by, the food's going to spoil anyway, so even if the labor wouldn't earn enough coin to pay for it, he very well might be willing to feed them for some basic labor anyway. On the flip side, maybe a blacksmith can expect to earn 10 pence shoeing a horse, but a blacksmith who really needs a roof over his head for the night might happily do it in exchange for a 5 pence room and a 1 pence meal. What's the nature of your heroes' journey? If it's something the innkeeper favors -- perhaps they're off to slay the evil witch that's been harassing travelers and thus hurting his income -- then perhaps he'll let them stay the night in return for the mere promise that they will succeed on the quest, or at the very least the hope that they will. On the other hand, if he's in league with the evil witch, he might still offer them that room -- and then inform the witch exactly where to send her flying monkey assassins that night! Bottom line: The money doesn't matter. It's a matter of how much the innkeeper values their work versus how much he values what he's giving in exchange. This is how barter economies have always worked; you can see it even today on numerous "For Trade" Facebook groups and Craigslist postings -- someone has something that is "worth" \$\$\$\$, and they trade it happily for something "worth" only \$\$. Did they get ripped off? Absolutely not (well, maybe not, at least...) -- they made a trade based on how much value the traded items have for them, not how many arbitrary units of currency would be required to buy them. Bottom line: Monetary value has very little to do with the exchange of labor/goods, except in the case where one is buying them with money. [Answer] Since you mention the date range: 1270-1400 there's another option: iron and steel. It varies depending on whether you're at the beginning or end of that range because cast iron was coming in around then and iron was getting a lot cheaper. If you intend for your world to be at the point where they have cannonballs iron will be cheaper, if not then iron will be very very expensive. (For context in Normandy ca. 1066, a healthy adult cow could cost about 12 ounces(340 grams) of iron and cows were quite valuable at that time) People don't realize just how valuable decent iron and steel was. Swords and suits of armor were symbols of wealth because the material needed to make them was so expensive. It's hard to get approximate prices from the time but a cheap sword looted from an enemy would easily pay for a night in an inn. Some metal armor would pay for a lot more. An apprentice blacksmith who's willing to steal and who doesn't intend to come home could also probably steal enough iron to fund a trip across the country. [Answer] They ran into baddies... Check their bodies for loose change. Depending on their skills and backgrounds there are a few jobs on [this list](http://abutterflydreaming.com/2009/02/06/100-medieval-careers/) that could be useful in an inn: Blacksmith: Shoe a horse, sharpen some knives. Rat catcher: The cellar has a few big ones. Minstrel: Sing for your supper. Storyteller: Because there's nothing good on TV. Otherwise, have them muck out the stalls. If I had a busy stable I'd probably let a few honest looking but down on their luck people clean it in exchange for some food and a place on the floor near the fire for the night. If the working it off isn't terribly important to the story, it's not out of the question for at least one of them to be carrying a purse with a few coins in it. EDIT: Regarding your edit, I'm looking into what a days work could be, which is somewhat difficult since most sources list average yearly wages. BUT, as Kromey pointed out, the biggest thing is not what the job would normally pay, but what it's worth to the inn keeper. For instance, if I had a horse that needed a shoe, and the closest blacksmith was miles away, couldn't get out to see me for a couple days, and would cost me 1 pence, I'd probably be more than happy to trade that for some food and a place on the floor. Likewise, if I had a stinky stable that needed cleaning and knew it was going to take a couple hours for me to do, I'd probably be happy to trade a meal not to have to do it myself. Same goes for entertainment. If you have someone with a good voice or some tales of adventure that no one has heard before, they would probably have the other patrons at the inn buying them drinks and stuff. You come off the trail, it's been a long day and you want to unwind a bit, and here's this person with a good singing voice and a rousting story to get your mind off your own troubles... It's a value for value situation, so you don't HAVE to get stuck on small details. [Answer] In the Middle Ages, Pilgrimages to Holy Sites were a big deal. There were travelers' aid stations and many were interested in helping poor pilgrims get where they are going. If they are willing to mix the travel with a pilgrimage (our noble heroes would never lie about being a pilgrim) they could save quite a bit of money at the expense of speed. ]
[Question] [ In a relationship between two species, could a certain relationship become harmful to both involved species? Keep in mind, I am looking for a relationship between two species, preferably of the kingdom animalia, although any example will aid my understanding. On an Earth-like planet, the known ecological relationships are [predation](http://en.wikipedia.org/wiki/Predation), [competition](http://en.wikipedia.org/wiki/Competition_(biology)), [mutualism](http://en.wikipedia.org/wiki/Mutualism_(biology)), [commensalism](http://en.wikipedia.org/wiki/Commensalism), [amensalism](http://en.wikipedia.org/wiki/Biological_interaction#Amensalism) and [parasitism](http://en.wikipedia.org/wiki/Parasitism). I would imagine that any sort of relationship that involves both being harmed would not start directly as that relationship; it would evolve to that as a result of a parasitic or amensalistic relationship. I can think of a few examples, such as a large horse-like animal that feeds on the same shrub as a small insect-like animal, which in turn gets ingested by the horse-like animal, and then attacks the horse-like animal from the inside. The end-game is that both parties are harmed. But I am looking for a relationship that is consistent and each of the parties is entirely aware of the relationship, but continues to engage in it. If such a relationship could exist, how and why would it evolve to be like that? As a side note, some of you might by gunning for me to mention neutralism, but I honestly don't care, it is a relationship that describes the lack of a relationship. Doesn't sound like much of a relationship to me. Please, no comments on neutralism. [Answer] Something equivalent to the [Prisoner's Dilemma](http://en.wikipedia.org/wiki/Prisoner%27s_dilemma) might work. If there are two behaviours to choose from for both parties which we might call "mean" and "nice" such that "mean" gives an advantage over "nice" regardless of the others behaviour, but both being "mean" is less desirable than being "nice" then the stable outcome (everyone mean) is harmful compared to the unstable ideal (everyone nice, but with a huge incentive to start being mean). There are ways out of the prisoner's dilemma, but they require repeated interactions with memory of what happened in previous iterations. Within a population that's sufficiently small that you can recognize and remember individuals, this can work. Across species, it would be much harder to develop. [Answer] A clear example of a mutaully harmful relationship would be that of competition. Both groups of organisms compete for the same resource (eg water, food, sunlight) and both species suffer negative utility from the existence of the other organism. This can be observed all over the world. As others have already mentioned, there is no sustainability in such a scenario, and this is an example of an unstable equilibrium. The two species will either: 1: Evolve into separate niches, which greatly reduces the issue of competition. 2: Have one species outcompete the other, resulting in the extinction of the less fit species [Answer] I think Uriel hit upon how it could happen--while we can be slow to realize we are in a destructive relationship, evolution can be much slower to recognize this. Thus picture a relationship that started out as a symbiotic relationship. Over the eons both sides of the relationship have evolved to exploit their partner to the point that both would be better off going it alone. However, the pairing behavior is programmed in and going it alone causes problems with attracting a mate, thus it's hard for it to evolve. (The odd animal that is born with a mutation that causes them to avoid the partner thrives but doesn't find a mate and thus doesn't pass on the mutation. To escape the trap you need not only the anti-partner mutation but one that removes whatever it is about the partner that's involved in mate attraction.) [Answer] There is no gain for any of the two species involved in such a mutually destructive relationship, so it wouldn't be a sustainable behaviour. On a side note : people sometimes engage in destructive relationships. Again, there is no gain for the involved parts, but we are sometimes not very fast to realize this. [Answer] So, the first thing I'd point out is that the only real reason to have any sort of relationship is for some kind of gain, whether it be for survival, emotions (like marriage), etc. One-sided relationships happen in nature a lot (predation) because one species is strong enough to say "I want this and I shall have it" and the other can't do anything about it... besides run away. SOME creatures have produced relationships where both succeed in a symbiotic state. However, the opposite would have no rewards for either species and they'd both have an incentive to leave that environment. The only place I can think to start looking would be an environment where a superior species purposefully or accidentally sets up an environment in which two lesser species are at odds with each other (like when two women are both really interested in the same man: their relationship is markedly non-symbiotic but neither wants to leave); I suspect an environment like this COULD occur in nature, but I don't know of anywhere it does. [Answer] A third entity is necessary to produce the illusion of a mutually harmful relationship. That entity must effect both parties negatively but through different mechanisms and the solution to each party's resulting malody must be provided by the other party. At this point, their relationship appears to be mutually beneficial because each party helps the other to survive the effects of the third entity, but relationships are never so two dimensional. Each of the two original parties has a strong parasitic or amensalitic secondary relationship with the other which causes significant damage to the effected party but not as much as the third party would cause if not for the negating effect of the other. ]
[Question] [ I understand that the Panama Isthmus is necessary for the Gulf Stream, but what would happen if instead of a solid land bridge, like shown below, it was radically changed into a series of islands during the 1st century due to an earthquake? How dramatically would it change the world climate? Edit: The earthquake was magical one, so not the natural flow of tectonic plates. [![enter image description here](https://i.stack.imgur.com/xp11g.png)](https://i.stack.imgur.com/xp11g.png) [Answer] It would not change that much. > > it was radically changed into a series of islands during the 1st century due to an earthquake > > > This description points to a situation where the landmass we have today would be replaced by islands separated by a rather shallow sea. Which is similar to the configuration at the strait of Gibraltar. In that situation the oceanic currents have a hard time flowing, meaning that there would be a weak connection between the Atlantic and the Pacific. As a consequence, there would be a limited impact on the climate, as the global oceanic circulation would not be drastically altered. [Answer] A frame Challenge. The theme song of the tv series Land of the Lost, 1974-1975, told how the protagonists were transported to a weird sort of pocket universe by "The Greatest Earthquake ever known". <https://www.lyricsondemand.com/tvthemes/landofthelostlyrics.html> As I remember, Geologists long ago debunked the idea of an Earthquake powerful enough to sink a continent like Atlantis. Of course what you are asking for would be the sinking of much smaller area and possibly for a much shorter distance. So possibly we need to find out the largest area ever subsisted in any recorded earthquake, and the deepest that any recorded earthquake has ever subsisted any land. I think that a major earthquake might drop land in an area of several hundred or thousand square miles (an area probably only tens of miles on its longest side) about a meter or so. So maybe something else could sink sections of Panama. I guess an asteroid impact could vaporize many mountains in Panama, instantly lowering the ground level to below sea level. As to how that would change history, it would exterminate the human species and all other large lifeforms, a significant historical change. It would be more plausible for a group of super advance extraterrestrials to decide they want to excavate a sea level panama canal, and make it much wider and much deeper than necessary for even the largest plausible ships to navigate through. Possibly the aliens have records of the oceanic currents and biology from before the Panama region closed the gap between the Pacific and Atlantic oceans, and wish to recreate the species of whales and sharks (megaladons) which inhabited it. Possibly the intent of the aliens may also be connected to the thousands or millions of cubic miles of rock their worker robots will excavate, and the islands or mountains they might build with that rock. ]
[Question] [ I am currently crafting a science fiction story in which humanity confronts an unprecedented threat: a novel form of 'heat death' that causes matter to cease to exist when it reaches certain temperatures. This event, initially manifesting with the disappearance of stars and the darkening of one half of the sky, eventually extends to Earth, transforming our lush home into a frozen wasteland. In this narrative, a mysterious quantum effect is driving this scenario. With the temperature threshold for this disappearance effect gradually reducing from stellar levels to the temperature at the Earth's core, it accelerates the universe towards a unique and imminent demise. As the Earth loses mass, humanity scrambles to innovate survival strategies and ultimately succeeds by creating pocket-dimensions. Within these pocket-dimensions, the laws of physics are not immutable, and they offer humanity a refuge from the advancing heat death. To ensure my story remains engaging and at least semi-plausible to readers with a rudimentary understanding of physics, I am seeking scientific and creative advice on two key plot points: 1. Hypothetical Quantum Effect: Can you help me outline a theoretical quantum effect that would cause objects reaching certain high temperatures to vanish from existence? While we are venturing into the realm of speculative science, are there existing quantum theories or principles that could give my narrative's phenomenon a semblance of believability? How might such an effect relate to current theories about the nature of matter, energy, and the fabric of the universe? 2. Identifying the Root Cause: In the context of my story, how might scientists piece together the truth behind these bizarre events? What kind of experiments or observations might lead them to deduce that heat is the root cause of the universal cataclysm? How could they theoretically measure that the universe's maximum permissible temperature is decreasing? Please bear in mind that while the story assumes an alternate universe with some differing laws, it should still retain a sense of coherence and intelligibility. [Answer] Frame challenge: Humanity's first indication is its sudden death Assuming that: 1. this effect is affecting the entire universe simultaneously; and 2. the decrease in maximum available temperature from hottest stars to Earth's core happens over a normal human lifespan, then the speed of light will mean that Earth's sun will have gone "nova" (see below) and destroyed the Earth before the light from other stars reaches our solar system. The problem is that the temperature of the sun's core is about 15 million K, while the Earth's core is around 5,000 K. As soon as the maximum "allowable" temperature for matter drops to around the sun's core temperature the interior will suddenly collapse and a variety of exciting effects will result in it exploding, destroying pretty much everything in the solar system and possibly well beyond, long before the Earth core temperature can be affected. Read Charles Stross' [Iron Sunrise](https://en.wikipedia.org/wiki/Iron_Sunrise) for a description of how this goes down (the root cause there is slightly different - coincidentally also involving a pocket universe - but the effects are largely similar). Astronomers may be able to observe a few minutes of changed solar activity before the near-lightspeed shockwave obliterates Earth. (An alternative scenario is that a nearby, larger and hotter star with a much higher core temperature goes supernova sufficiently long before our sun goes nova that its shockwave reaches and obliterates us first, but the practical result is identical.) In summary, rather than the sky slowly going dark, this effect will destroy solar systems. The only way that we could gain information about this effect before being destroyed by it would require that the area affected by quantum/handwavium destruction is propagating through the universe at much less than lightspeed - this might allow Earth astronomers to detect enough novae and supernovae that are far enough away from Earth for detection not to be accompanied by destruction. With enough data points they might be able to figure out what is going on. If that premise is adopted, then note that the race is to get into a pocket universe before the sun goes nova, not a race against Earth getting cold. [Answer] False vacuum decay has some history in doomsday fiction. <https://en.m.wikipedia.org/wiki/False_vacuum_decay> Basically a bubble forms and grows in the universe ripping a new set of physics rules in the universe. Now if you want to mess up a huge chunk of the universe simultaneously (Though note there's no way to observe that it you stick to real physics) A brane collision will be rather catastrophic and energetic and you can fictionally do whatever you want since this is so theoretical. Want to get rid of mass - maybe have it get dragged into the other brane. <https://www.science.org/content/article/cosmic-radiation-features-could-suggest-our-universe-not-alone> <https://www.sciencenews.org/article/when-branes-collide> Of course in reality if you alter the laws of physics even slightly it probably means instant death because life is chemistry following those laws. Edit: on further thought since you want heat to play a role. Let's say that brane collision between universes happens. You could then claim that high energy particles are quantum tunneling into the other universe. This would mess up the insides of a star but leave regular chemistry alone. You could further claim that as the collision proceeds the energy to cross the barrier is decreasing. So maybe it gets to the point where a planet's core is losing particles. This is very much an abuse of tunneling but then again tunneling isn't meant to cross universe boundaries either. <https://en.m.wikipedia.org/wiki/Quantum_tunnelling> Edit 2 Also note tunneling is a statistical event for each particle. So you can define the rate of loss to suit the plot. That is for something at 5000 degrees you lose 0.01% per year. [Answer] As said in Lucasbachmann's answer I think you want a False Vacuum decay. (copy his link: <https://en.m.wikipedia.org/wiki/False_vacuum_decay>) Vacuum, in quantum physics, is supposed to be the lowest energy state of a system. False Vacuum decay is a hypothetical situation, where what we call "vacuum" is not in fact the lowest energy state, and is thus a "false vacuum". If this hypothetical were true then a phase transition is possible, where a bubble of true vacuum forms (somehow) and then spreads outwards in all directions (probably at lightspeed). Everywhere inside the bubble physics would be quite different, with different particles and forces. However, importantly for your scenario, heat would (to some extent) resist the vacuum phase transition. A lower energy state is only an attractor at low temperatures. So hot stuff could (handwavy) be made resistant to the transition. Given that the expansion speed is lightspeed I think it would very much feel like it was happening everywhere at once, as one second we would not be in the bubble. Then a second later the whole Earth would be, the vaccum outside earth changes in some mad way but the Earth itself (hotter) only starts to change slowly\* (out from the edges of the atmosphere). \* I think this aspect is not really physically right, but suits the stroy and the "heat protects" handwave. [Answer] I dont think you would need something that fancy, energy excites matter, if matter gets too excited it will most likely try and desperse (Explode) due to high internal tension/pressure.Explosions in space are pretty mild compared to inside an atmosphere, and there you have an explanation that fits the story,people stop seeing light but nothing catastrophic happens (for now). I cant explain any effect that would do that, but since we can bend physics a little (Various things explode when too hot,why not a star ?) but that does lead to something making the stars spontaneosly get warmer and cross the threshold to go BOOM. Quantum mechanics are way to complicated to explain something that simple IMO, but its your story ]
[Question] [ I'm working on a character for a story that has the ability to somewhat play around with gravitational forces, mainly weight reduction stuff but I'm sure there's other applications. Practically this would mainly be used for her to use a weapon that would normal be a bit too unwieldy and heavy without the power, but then I was curious because Force is mass x acceleration, which doesn't reflect weight. So would a large sword with reduced weight but the same mass still do the same amount of force when swung or potentially even more due to the increased acceleration from it being light, or am I mistaken somewhere? The only thing I can think of is that maybe air resistance or drag could affect the lighter but large weapon. [Answer] # The Other Option: Messing with the Gravitational Constant As other answers have pointed out, you could say the magic decouples gravitational and inertial masses. If you want the magic to work this way, which is likely something beyond what most consumers wish to comprehend in many genres and media, then those are the answers for you. There is another option, though. Looking at [newton's law of universal gravitation](https://en.m.wikipedia.org/wiki/Newton%27s_law_of_universal_gravitation), you could say the magic messes with the universal constant to make it... Not so constant. Something like defining a local "for this set of atoms, make the constant a different value" sort of function. This gives a weapon which is light to carry, but still takes the same amount of force to accelerate (in most cases). The benefit here is that it allows for normally fatiguing guards to be easily maintained. Things like [several of these German longsword](https://wiktenauer.com/wiki/Category:German_Guards) guards, especially Vom Tag, Ochs, or Langenort. (Italian and Japanese swordsmanship have parallels to a lot of these!) This is usually not an issue for well trained individuals over "short" time periods, but then again, they are trained for it and not wielding stupidly large/heavy weapons. Additionally, these guards are usually not positions to "hang out" in, so a fighter would strike from one and move into the next guard. # The Downside of Decreased Mass You do not want decreased (inertial) mass to make the sword easier to swing, because that means the sword is easier to deflect and block! Unless this magic dramatically increases or decreases effective mass within fractions of a second, can choose which forces from which people to experience, or creates a separate "gravitational but not inertial mass", this magic is a bad deal for weapons. A weapon's (inertial) mass is crucial to its behavior in combat. Removing that inertial mass makes it harder to deliver required blows and the alternative, removing the gravitational mass, doesn't negate the forces required to actually accelerate the weapon. # Better Idea: Throw Things Up! Wait, don't downvote just yet! This magic could be better used to throw projectiles, give them their weight back mid air, and see them fall with increased energy. In the case of projectiles, you can more easily throw them as only drag would slow them down. Give them their mass back in flight and you have a sudden increase in potential energy, which means bigger impact on the other side. # Better Tactic: Use It On People Alternatively, consider that a lot of martial arts requires a stable base. Suddenly becoming 50% lighter in combat is a big deal. It's enough to throw you off balance, trip you up, and allow for a competent foe to take you entirely out of the fight. Additionally, becoming 50% lighter yourself can cause you to pull literally impossible maneuvers that most fighters simply have no experience with. A bounce in your step becomes a leap, your forward lunge a charge, and so on. It would take training to fully take advantage of this, but it would certainly make disengaging (a crucial part of not dying in armed fighting/duelling) really easy! [Answer] For the purposes of your character, and since you've included the "magic" tag, this can work any way you want it to to fit your story. Perhaps your character can decouple gravitational mass from inertial mass, or perhaps they can locally flatten space-time so particular objects don't feel (as much) gravity, or perhaps they only think of it as a gravity effect but in fact they have a (psychologically?) limited form of telekinesis that lets them handle some heavy objects as if they were much lighter. In the last case, they might be able to pick up a two-handed greatsword as if it were a small wood dowel, swing it the same way, but still have it impact with its full weight, potentially (given skill, senses, and reflexes to back it up) making them a whirlwind in melee combat. [Answer] Using this as a weapon is pretty obvious. Lift the hammer with weight set low. Bring it down with weight set high. So your hero can lift, say, 30 pounds without the special effect. But 1000 pounds with the effect. Just to have numbers to think about. And also to have a size to think about, 1000 pounds of steel is round about 2 cubic feet. That is, a not very large aquarium sized object. Roughly 60 liters for the metric fans. About 16 US gallons. So they lift the huge weapon. Then just turn off the "juice" when the object is over the enemy's head. Smack! Make sure to step back and not let your own weapon hit you. If they get in a good hit, it's time for mead and cakes with the other supers. If they miss, well. There's now a 1000 pound hunk of steel on the floor. The enemy isn't likely to be picking it up and hitting back. Meantime they can choose alternative weapons. Like small cars, furniture, other superheroes, etc. Depending on how much it "takes out" of the hero, this can have lots of other possible uses. It's a Dungeons and Dragons trope to be able to use this sort of thing as a trap. Imagine being able to lift a ton of any cheap material. Sand, for example. And carry it up some stairs, and place it behind some barrier. And arrange the barrier to be spring loaded and open when the victim steps on the trigger. Suddenly they get a ton of sand dumped on their head. If one ton is not enough, then make twenty trips. If it does not tire the hero, it's just walking up a flight of stairs. Making a waterfalls run backwards can have lots of interesting effects. This town over here gets on your nerves? Flood them out. [Answer] Let me present two situations for you. 1. Pick up a large book, and put your other hand on top of it. Shake it up and down. The difference between the "up" and "down" is gravity. 2. Take the same book and hold it vertically between your hands. Shake it left and right. What you're experiencing there is momentum. That feature will exist regardless of the gravitational field it's in. If your power just effects gravity, a weapon that has no weight will still have momentum. * It will take less effort to lift * It will require most of the effort to swing. * All impacts, whether they're from above, side, or below, will have the same force as a sideways swing. * Overhead swings will not have weight advantage, and that's most of what you get with an overhead axe or war hammer swing * Underhand swings will have more force than expected, but you still have to worry about hitting the ground * It will provide no advantage with accuracy, as that's a momentum and reaction-speed thing. Given all that, you'll be able to use polearms to greater "poking" advantage. Opponents would be expecting to be able to knock them down, but will be faced with the weapon's full momentum with no gravity assist. [Answer] In strictly scientific terms, the gravitational mass is the mass that we measure with gravitational effects, that is how strongly a given mass attracts another mass, while the inertial mass is the quantity we measure with the formula you quote, that is how much a mass resists the effect of a force. They are the same because of relativity, but with different physics they might be independent. Therefore if you want to be strictly scientific, your hero when swinging around an oil pipe with this power will have the same effect of swinging a pool noodle. However, if your character can decouple the gravitational and the inertial mass, she changes only the gravitational effects but not the inertial ones and can very plausibly wield a massive weapon without worrying about its weight and not giving up the inertial effects associated with it. However the above messes up with relativity, so stay away from it in your story. ]
[Question] [ How does having super strength/speed but similar mass to a regular person change close combat fighting? This world is a cultivation world. That's a world where people can cultivate abilities by using techniques and a fictional energy unique to that universe. What they cultivate are essentially like super powers. Super strength, Super speed , elemental powers and such. It's science-fantasy so it's got some tech in their to but leaving it out at the moment for this. The main issue here is I do plan on increasing their mass/density as they get a stronger body but the mass will be much less then you'd expect for their level of strength. So I suppose I'm trying to picture what happens when two people grapple and strike each other with super strength but don't have a correspondingly high mass. I don't have any concrete numbers but I think a general ratio of mass to str/speed increase would be 1.5:5. So someone with 1.5 times the average mass of a person would be like 5 times stronger and faster. A very generalized example. A side note: The environment is also tougher then normal (another effect of the cultivation energy) so it's unlikely they'd break everything as they're moving around. I also wanted to add a method for them to disperse the force they emit as they push off things to a wider area as another reason they don't destroy things all the time moving around. [Answer] Low mass means more throwing and less struggling From the perspective of classical physics, what you have here is really nothing more than the difference between elastic and inelastic collisions. > > In physics, an elastic collision is an encounter between two bodies in which the total kinetic energy of the two bodies remains the same. In an ideal, perfectly elastic collision, there is no net conversion of kinetic energy into other forms such as heat, noise, or potential energy. ([Source](https://en.wikipedia.org/wiki/Elastic_collision)) > > > > > An inelastic collision, in contrast to an elastic collision, is a collision in which kinetic energy is not conserved due to the action of internal friction. In collisions of macroscopic bodies, some kinetic energy is turned into vibrational energy of the atoms, causing a heating effect, and the bodies are deformed. ([Source](https://en.wikipedia.org/wiki/Inelastic_collision)) > > > Light weight superheros are, IMO, more along the lines of elastic collisions. There's really nowhere for the energy to go, so they go flying! Contrast this with more massive superheros where there's someplace for the energy to go, resulting in your opponent sweating from the increase in heat! I mean, let's face it... high energy + low mass simply means less force is involved, but it also means less friction is involved... which means leverage IS involved — which means more brick and asphalt is involved. What's the difference between two buck-and-a-quarter superheros and a couple of six-fifty superheros? People being thrown through the air! Whoever has the best leverage will more easily throw the other person. Scrapes across the asphalt... getting up close and personal with brick walls... lots of dry cleaning! And you want those throws because, without the mass behind your fist, you just don't have the punch needed to take your opponent down! (You know, F=mA and all that....) Which means using his/her mass against them! Viola! Superhero physics 101! As mass increases there will be less throwing and more struggling because the effort to get someone off the ground is higher (and the amount of time they'll be in the air will be lower...). Your fist will have more impact (as will kicks and, of course, taunts. Taunts always get better with more mass...) — but so will strategy! After all, the mass of your opponent will certainly work against them with greater effectiveness! It just means you need to plan the fight next to the Grand Canyon so you can propel your opponent over the edge. I'll be signing autographs in ten minutes... check out my merchandise in the tourist kiosk! [Answer] Rassling. Consider that for fisticuffs, your supers must be durable. If I could punch 5x as strongly as I do now I will break my hand. I am actually pretty likely to break my hand as it is. So you will need to make your supers stronger in the anime sense: both stronger and more durable. If people are more stronger and more durable but have low mass because they are built like supermodels then when hit or kicked they will go flying but not be much hurt. The super doing the hitting and kicking would also go flying unless efforts are made such that impact of the blow is mostly up so the equal and opposite vector mostly down into the ground: these would be groin kicks. Really though these high strength low mass durable supers are going to wrestle. Kicking people high into the air is good for laughs and impressive for the anime but when they descend unhurt the fight just takes longer and it is already past dinner. Murderous supers will wrestle and use steady applied force to tear fancy clothes, pull off hair and other loose bits, bend the bendy parts the wrong way, squeeze, choke, gouge and just generally be mean to one another in a writhing heap on the ground. --- It seems so unspectacular, these lithe supermodel eyecandies ruining their clothes, groaning and hurting each other. Might I suggest ritualized combat - turn based duels with the winner the one who can kick the loser highest into the air, or cause the struck loser to tumble in the air the most times (because the winner put spin on the blow; tricky!), or make the loudest noise with an open hand slap to the losers bared skin? These things would make for fine anime! [Answer] Short Answer: It changes it completely. Longer answer - I think what you are asking is based on the fact that in most combat sports, we have Weight classes. These primarily deal with two issues: 1: People with more Muscle can generate more force and therefore hit harder (Muscle weighs more than fat) 2: Taller people and those with denser bones have certain advantages. However, that is when we are comparing a like-for-like scenario e.g. 2 humans of comparable strength. Once you add a significant advantage - Mass isn't going to mean anything. Super Speed for example - you can block faster, you can dodge faster, you can strike faster - your strikes will be a lot more devastating etc. You can flank faster and exploit your opponents openings/weaknesses faster. The list goes on and on. Super Strength - apart from the obvious advantage in striking, grappling would likewise be a cakewalk. Think of a Dad play-fighting with his 5 yo son. That's what it would look like functionally. The only time Mass might be a factor is if their opponent physically lifts them up... However - we have super strength, we reach down grab their arms and crush their wrists - problem solved. Or we have super speed, the moment they try to grab us, we just run away. TL;DR - Mass is irrelevant in close combat when Super powers are involved. [Answer] Imagine a fight on the moon, but faster. If two combatants are 5x as fast and 5x as strong, they can treat gravity as being 1/5th as much of an issue. You'd wind up using your environment in order to get enough leverage to take advantage of your full strength and speed. They would have to lower their center of balance just to avoid falling over from their own punches. When hit, a person would actually be knocked back a significant distance. You'd see a lot more parkour, of course, and property damage, but that's a given when your durability exceeds that of your environment. Imagine a brawl in a room full of cardboard furniture. On the moon. Yea, that would be fun. Addendum: Even if you can build furniture stronger, you probably wouldn't, for economic reasons. When we can build it out of stronger materials, we use that advantage to make the furniture lighter-weight. [Answer] Not entirely clear from your description what distribution in abilities there is and if people can have increases in more than one. If people have massive advantage in strength, they will use grappling techniques and seek to grab hold whenever possible. If you're strong enough, you just break whatever bits of someone you get your hands on. Speed is somewhat orthogonal to strength. It depends on how gory you want to get and if most combat is to the death. If you're that much faster than someone you start by blinding them with eyestrikes they cannot block. If you're able to use a blade, you use a massive number of fast cutting passes to cause them to bleed out. (Latter emphasised in John Ringo's We Few). Writing as martial artist & SF/F reader for decades, no actual combat experience but one of our senior black belts is a police officer and army reservist. He provides useful real-world qualifiers on our techniques. Also, our kung fu style is one of the more combat-oriented in history. [Answer] With super strength and higher speed but unchanged mass I will break your wrists, your arms, your legs, your neck in that order. Game over. As long as my body can endure the effects of my strength. If my hands get destroyed when I break your arm then things are a lot harder. But I think my body can handle much more than my actual strength, so twice the strength is likely usable without negative side effects on myself as long as I don't use it too much. ]
[Question] [ The planet is just like earth and the first moon is the same as earth's moon, but there's a second moon further away. I'd like to know how plausible it is for both moons to align once a year. The second, further moon appears smaller in the sky compared to the first one. Would it even be plausible for them to align once a year without changing the orbit of the first moon? [Answer] As a first approximation, the closer the orbital distances, and thus the orbital periods of the two moons are to each other, the longer will be the period between successive line ups of the two moons. And the farther the orbital distances, and thus the orbital periods of the two moons are from each other, the shorter will be the period between successive line ups of the two moons. For example, in our solar system Earth orbits the Sun at 1 astronomical Uint, or AU, and has an orbital period of 1 Earth year. The farthest known planet, Neptune, orbits the Sun at 30.07 AU, and has a orbital period about 164.8 Earth years long. It has a synodic period between orbital alignments with Earth of only 367.49 Earth days, slightly more than one Earth orbit of the Sun. The planet Mars, in the next orbit beyond Earth, orbits at a distance of 1.523 AU, and has an orbital period of 686.980 Earth days or 1.88085 Earth years. It has a synodic period between orbital alignments with Earth of 779.94 Earth days, or 2.1354 Earth years. so the outer moon in your story will have to orbit les than 1.523 times as far as the inner moon, and have an orbital period less than 1.88085 times as long as the orbital period of the inner moon. The Moon has a sidereal orbital period of 27.321661 Earth days, shorter than the Moon's cycle of phases. The Earth has several different types of years defined differently, but you probably want the tropical year, the year that defines the seasons and is the basis of solar calendars, 365.24219 Earth days of 86,400 seconds each. So there are 13.36822787 lunar orbits in a tropical year of Earth. Thus the relative separation of the two moons' orbits would have to be much less than that between Earth and Mars for their synodic period to be 13.36822787 times as long as the orbit of the inner moon. Two moons of Saturn, Janus & Epimetheus, orbit Saturn in orbits very close to each other. According to Wikipedia, in 2003 the semi-major axis of the orbit of Janus was 151,460 kilometers, and the semi-major axis of the orbit of Epimetheus was 151,410 kilometers. So in 2003 Janus orbited about 1.000330229 times as far from Saturn as Epimetheus did. With the two orbits so close, the inner moon orbits only very slightly faster than the outer moon does, and so it takes about four Earth years for the inner moon to pull ahead of the outer moon and then catch up with it again. And every time the two moons get close, they switch orbits, so the former inner moon becomes the outer one, and the former outer moon becomes the inner moon. So if the outer moon in your system orbits only 1.000330229 times as far from the planet as the inner moon does, there should be about 2,404 orbits of the inner moon between each time the two moons line up. If the inner moon has the same orbit as Earth's moon, the time between successive alignments of the two moons will be about 57,489.58641 Earth days, or 157.39 Earth years. And if the outer moon orbits about 1.523 times as far as the inner moon, the time between line ups of the two moons will be 2.1354 times the orbital period of the inner moon. If the inner moon has the orbital period of Earth's moon, 27.321661 Earth days, the time between successive line ups of the the two moons should be 2.1354 times as long, or 58.3426749 Earth days, or about 0.159 Earth years. So for the two moons to line up only once a year, the difference between their orbital distances and the difference between their orbital periods has to be between those two extremes. According to this list: <https://en.wikipedia.org/wiki/List_of_exoplanet_extremes> The smallest known semi-major axis ratio between the orbits of two consecutive planets in the same system is between Kepler-36 b and c. Planet b's orbit has a semi-major axis of 0.1153 Astronomical units (AU) and a period of 13.86821 Earth days. Planet c's orbit has a semi-major axis of 0.1283 AU, 1.11274935 that of b, and a period of 16.21865 Earth days, 1.169484021 that of b. <https://en.wikipedia.org/wiki/Kepler-36> According to this synodic period calculator <https://www.omnicalculator.com/physics/synodic-period> the synodic period of c as seen from b would be 69.694 days. That is 6.900241632 times the orbital period of the inner planet b. So if the the inner moon in your system has an orbital period of 27.321661 Earth days, and the outer moon orbits 1.11274935 times as far from the planet, and has an orbital period 1.169484021 as long, the synodic period should be 6.900241632 times 27.321661 days, or 188.5260558 Earth days, or 0.51615621 Earth years. According to my calculations on this synodic period calculator <https://www.omnicalculator.com/physics/synodic-period> if the inner moon has an orbital period of 278.321661 days and the outer moon has an orbital period of of 29.53069 days the synodic period should be 365.241 Earth days, while if the outer moon has an orbital period of 29.530699 the synodic period will be 365.239 days. And that is as close to Earth's tropical year of 365.24219 Earth days as I could get it. And of course that assumes that the star is exactly like the Sun, the planet orbits with the same distance and orbital period as the Earth and has the same mass as Earth, and the inner moon orbits the planet at the same distance and orbital period as the Moon orbits the Earth. Anyway, I hope I have shown that the problem of getting a planet's two moons to align once a planetary year is not unsolvable. Added 11-06-22. Afer consieration, I strongly suggest that both moons hav emuch less mass than Earth's moon, so that they appears as dots or very tiny shapes in the sky of the planet. That will make them much less spectacular as seen from the surface of the planet. But by greatly lowering their masses, that will reduce their gravitational interactions and so reduce the probabability than one will be ejected from orbit around the planet. Each planet orbiting a star, and each moon orbiting a planet, has an exclusion zone where its gravity will tend to eject less massive objects. Thus the usual spacing of planets areound a star, or moons around a planet, is rather wide, with each orbit being significantly wider than the next inner orbit. The examples I gave above of planets and moons with narrow separations between orbits are rather unusual examples. Thus you should greatly reduce the size of your two moons so having their orbits so similar will seem more plausible. [Answer] If the two moons orbits lay in the same plane it's impossible: though the outer moon might take longer to orbit the planet, the inner moon will necessarily align with it more than once through the entire duration of the outer's orbit. If the two orbital planes are instead differently inclined, I think you can find a configuration where the nodes are met once a year, more or less in the same way as our moon and sun do not eclipse each other at every new moon/full moon but only at longer intervals. [Answer] Assuming by "align", you mean that the moons eclipse each other as seen from an observer on the planet, that happens all the time in multiple-moon systems. On the planet, if the little moon is naked-eye visible, they'd be lunar eclipses and happen predictably & frequently, maybe with different names for Moon B in A's shadow/blocked-from-view vs Moon A/B in Planet's shadow, like ours. Formal name for a body passing in front of others is an occultation [(Int'l Occultation Timing Association, What is an Occultation?)](https://occultations.org/occultations/what-is-an-occultation/). Here's an [EarthSky article](https://earthsky.org/astronomy-essentials/jupiter-equinox-mutual-events-moon-2021) from 2021 discussing viewing Jupiter's moons occulting each other. From Earth we can only see them at Jupiter's own equinoxes, so twice in its solar-year (akin to our start of Spring/Fall), but that's due to how the large Jovian moons are aligned with each other & Earth. From an observer on the central planet, the eclipse frequency would depend on relative "months" for each moon, their relative sizes, orbital distances/speeds, etc. It's mostly-independent from the length of a year. It's similar to how our lunar month is mostly unrelated to the length of our solar-year. Earth has 12ish lunar months per solar-year, which is how you get a "blue moon" - when that 13th partial-month happens to include a full moon. So your world might see an eclipse of its lunar-pair "once in a blue moon" :) ]
[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/223301/edit). Closed 1 year ago. [Improve this question](/posts/223301/edit) The question is: If i could replace my arm with the arm of someone older than me, would the fact that the cells in the transplanted arm are older cause any specific reaction? Please handwave all genetic incompatibility issues except for the age of the transplanted organic material. And let´s assume that the full transplant is possible and goes well. I remember reading somewhere that the cloned sheep Dolly seemed genetically older because they used an already existing cell in her making. Or is my memory broken? [Answer] # No Because the cells in Your transplanted arm wouldn't be older than Your own. Our cells are constantly dying and being replaced by new cells, so the "average cell age" is roughly equal among people (with the exception of newborn babies) [Answer] # More inflammation and pain. Older cells have shorter telomeres and other signs of aging. The older cells would as such die more often or fail to work, and so the immune system would have to remove cells from it more often. This is normal for aging, and wouldn't be a massive issue. [Answer] # No: If we assume an ideal situation, with a person's identical twin (with the identical egg developed years later), then the early twin's arm being cut off and attached to the younger body, there should be no rejection unless an exotic element is added. The older body may, for example, attack the younger one due to an autoimmune disease. For example, if a person had the genes predisposing them to Celiac disease, and the older arm had some of the cells producing anti-gluten antibodies, those antibodies could then attack the digestive tract of the person getting the donated limb (effectively causing celiac). An old person with a weakened immune system could have a disease such as CLL, and the young body might successfully recognize the cancerous cells as foreign, so then the young body could potentially destroy any (defective) bone marrow in the arm of the old limb. Or the older may harbor an infection that the younger body recognizes as foreign. But these are exceptions, not the rule. I don't know of a lot of Frankenstein-style experiments like this personally, so it's a bit hard to say definitively how differently aged cloned body parts would react for sure. Older bodies do tend to have fewer stem cells and shorter telomeres, which may help repair damage. But the role of stem cells and telomeres both in aging is a bit controversial, to sat the least. Almost anything involved in tissue growth and regeneration is also at least in part associated with cancer. What you are thinking of in terms of cloning is that the differentiated tissues, which have gone through many rounds of replication, are both hard to "un-differentiate" into stem cells that can perform all roles of body cells, AND that "older" cells may have short telomeres which protect against the effects of cellular replication. So the Dolly clone was essentially older, and suffered negative effects of age at a much younger age due to this (this is over-simplifying). If you want to know more, read [HERE](https://en.wikipedia.org/wiki/Dolly_(sheep)#:%7E:text=Dolly%20lived%20at%20the%20Roslin,the%20disease%20to%20her%20cloning.). [Answer] Organ donors are often older than the recipients. Consider living donor liver transplantation. [Liver transplantation for pediatric inherited metabolic disorders](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5142218/) Suppose it turns out my new baby has an inherited genetic disease; perhaps [maple syrup urine disease](https://en.wikipedia.org/wiki/Maple_syrup_urine_disease#Liver_transplantation). I have a large liver by virtue of my overall largeness. I can easily do without the small left lobe of my liver. That left lobe is as big as my child's whole little liver! So I donate my left lobe. Baby is cured of the maple syrup urine by my donated liverly awesomeness. Usually parents are the living donors for babies with these issues. I am sore for a while but fine. I here assert that parents are in all instances considerably older than their children. So baby's new liver is as old as baby's parent! Or even grandparent. That is just fine. If baby grows up with unexplained fondness for Led Zeppelin I will nod knowingly. ]
[Question] [ Seedgirls look like ordinary girls but they have a big green bulb on their head. This bulb holds a powder they use to speed and enhance plant growth. My question is how the bulb gets there in the first place. Here's why: 1. The bulb could be a part of their body, but that would mean they are essentially humanoid plants, and this would be almost impossible to evolve. 2. The bulb could be a symbiotic plant, but then why does the bulb rest atop the head. This is still a vulnerable position and the bulb could easily get whacked, sliced, or otherwise hit as the seedgirl walks through her forest home. And, of course, why did the plant develop a symbiotic relationship with the seedgirl in the first place? 3. The bulb could be a parasitic plant, controlling the humanoid through tendrils that penetrate through the skull, using special spores to expand its neural network (and by extension, its power). However, I really don't like this possibility and it doesn't quite fit with my vision. So, to restate my problem, these symbiotic bulbs rest atop the heads of their hosts, a race of forest-dwelling women. How did they get there? To make things even clearer, how would a bulb end up living in harmony with a human atop their head? The ideal answer will: 1. Explain what benefits a plant would have for a forest-dwelling woman and vice versa. Perhaps the plant contributes energy and nutrients in exchange for mobility and protection. 2. Explain how the relationship could have happened. This seems pretty necessary, since nothing quite like this has happened on Earth, unless you count algae and fungi growing in wet sloth fur to be similar. 3. Explain why the bulb is on the hosts head, despite the drawbacks of being positioned there. Is there any advantages of it being here as opposed to somewhere else. What would be a better place? How would this change the appearance of the Seedgirl? Attention All Answerers: I have not selected one answer here because I cannot pick just one of these many excellent answers. Everyone, please accept my gratitude and appreciation, as I will be using parts of each answer. [Answer] # It's not just Symbiosis: It's Culture The bulb could be part of some regular epiphyte/parasite, perhaps with some adaptations for living on animals. The universal presence on the seedgirls' heads could then be explained as some sort of cultural practice This cultural practice would be easy to explain as a practical decision; If their food source is dependent on plants (which it will be), then the growth-speeding powder of the bulbs will be invaluable to them. And putting the bulbs on your head is a rather efficient way to make sure you always have some powder available The top of the head specifically is also a pretty good place for the plant. It is balanced on top of the skull, it is easy for the seedgirl to reach, and if it's parasitic then the important organs/muscles should be well protected [Answer] Repurposed Echo Chamber in Skull. The benefits to each partner are obvious. The plant becomes mobile and less likely to be eaten. The girl gets access to magic powder that they use for growing more plants to eat. By the way the bulb is tough like a cabbage and so resistant to all sort of knocking around. [![enter image description here](https://i.stack.imgur.com/L8HcD.jpg)](https://i.stack.imgur.com/L8HcD.jpg) Some people like to bounce a football on their head, but would you risk bouncing a cabbage? Thought not. The bulb is attached to the top of the head, to a chamber in the skull that was originally used to generate loud calls. See the picture of a male elephant seal: [![enter image description here](https://i.stack.imgur.com/nboOM.png)](https://i.stack.imgur.com/nboOM.png) This gives the roots something to cling to, without going inside the skull. For a more extreme example of an skull echo chamber here is a Parasaurolophus: [![enter image description here](https://i.stack.imgur.com/wJCuW.png)](https://i.stack.imgur.com/wJCuW.png) [Answer] How do the pods develop? The bulb is semi parasitic. Plants would drop their sticky seed pods on animals. The sticky part of the pod would then send roots or rhizomes into the animal to draw the nutrients develop the seeds/spores. Conversely, the seed pod is just the fruiting body of a rhizome infection. Either way, it was a way to spread seeds/spores farther using something else's energy. The pods would, over time, develop numbing agents and would restrict their draw on their host. The numbing agent would both prevent the host from curling up, waiting to die and from rubbing the bulb off to get rid of the pain/itch. That combined with lowering the rate of draw would allow the pod to remain active longer and allow the animal to get farther away from the plant which would allow the seeds to spread even farther. Eventually, the pods would operate at a slow enough speed that they were a permanent part of the host. Also, since the pod is getting "free" energy. Why not also create some kind of fertilizer to help the seeds grow. The fact that this fertilizer also helps other plants, is just a side effect. Why do only the "pod girls" have it? Animals operate better without a drain on their system. Therefor they would develop an immune response to the rhizomes and fight it off like an infection. At some later time, some humanoids colonize the island/continent. They have no immune response developed. The pods are already not harmful. And they find that having the pods makes food more abundant. The pods could then become a symbol of plenty, possibly with religious overtones. Why are the pods on the heads? Well, the head is out of the way. It is less likely to get damaged by the host's own movements. If the pod is simply the fruiting body, it may have gotten brushed off of animals in other places and had to draw more energy from the host to re-form it. In the course of lessening the burden on the host, the pods eventually began developing in areas that were less and less likely to get damaged. Is it congenital or induced? Your choice. The rhizomes could infect the fetus and only produce the fruit when the child is of sufficient size to support the drain. Or, for luck or religious observation, the humanoids could purposely touch their heads to the parent plant to be bestowed the blessing where all could see it. After a while, it could lose the original meaning and just be a thing that some young girls do when they reach a certain age. Why only girls? Well, if it isn't passed on from birth, the answer is cultural choice. If it is passed on from birth then there is the option that males lack an enzyme or have an immune response to it. If there are only girls of this humanoid race, I leave it up to you as to how that happened. [Answer] ## Why bald men need sunscreen First, an obvious point: your plant wants to sit on the Seedgirls' heads because it's the position where it gets the most sunlight. Pretty much all plants display [phototropism](https://en.wikipedia.org/wiki/Phototropism), preferential growth toward the light. So the plant doesn't actually need to attach itself to the girls' heads at all; it could start growing anywhere on their body, and slowly but surely move up towards the light until reaches the crown of the head and it can move no further. Only at this point does the plant body (the big green bulb) really develop, so it looks like they only "grow" there, but in fact they can be found in faint tendrils anywhere along the body of young girls. Maybe the plants respond to the hormones that girls produce in puberty and move a lot more, or establish themselves better, when these hormones are released, explaining why the bulbs are only found in girls. You could also imagine cultures where heads are kept covered, and for these Seedgirls the bulbs would grow in a different location (presumably kept bare for this purpose). But this still doesn't tell us what they are doing there. Look, if I'm a plant and I can get my food from the Sun, why would I want to be carried around by a random Seedgirl when I could just sit on a nice sunny rock? ## Why do we have a head anyway? The bilateral body plan has been a [stonking success](https://en.wikipedia.org/wiki/Bilateria) among animals. One of the reasons is that it creates a natural axis with a "front end". This front end contains the sense organs and is also the driver for the direction of movement, a stupendously effective arrangement to a) find what you want and b) go get it. Our plant is hoping to capitalise on this because it has the ability "sense" something and needs a method to move towards it (quickly). The symbiotic agreement therefore is this: the plant provides a new, non-human sense (electromagnetic fields? The distant call of plant pheromones? Magic? The future? It's up to you) which is useful to the human - for example, it may help the Seedgirl find hidden oases in a hostile environment. In return, the Seedgirl (to a degree of voluntary choice that is for you to decide) follows the bulb's directions to the place that this sense points to. Maybe she is in complete control and their goals are simply well aligned, so what she chooses to do is usually beneficial for the plant as well. Maybe the bulb releases enough psychoactive molecules that the Seedgirl is pretty much unable to resist the plant's commands. Or maybe it's somewhere in the middle, with the Seedgirl experiencing a lovely sense of joy and fulfillment whenever she does what the plant desires, but still free to reject it (this might make for a good story hook? Conflict and all). As to how this all started, I'm going to make a storytelling rather than worldbuilding suggestion that you don't necessarily have to explain it. Often, alien/fantasy biology works best with a show-don't-tell attitude, just treating the fact as relatively mundane in your setting. Everybody knows that Seedgirls have bulbs on their head! Some say it's a gift from a God, answering a prayer when humans were at the brink of starvation and extinction. Some say it's a disease, that the Seedgirls are not fully human because of it. Some say it's just a symbiotic plant relationship. You're allowed to not explain. [Answer] It is a symbiosis originated by ritual (probably religious) in the seedgirls' culture. They aren't born with it, but they are born with the ability to connect it to themselves. So they aren't quite exactly human, either. Suppose there was a humanoid race of animals that could absorb and sustain plant matter, and they were intelligent enough to observe that this plant caused accelerated growth in other plants. Suppose they knew they were capable of absorbing plant material. It's fairly reasonable that they would consider this plant holy (especially if they were generally religiously inclined) and their holy people would be chosen to bond with this plant and spread it for the good of their society. And of course, it would then also make sense for them to live where the plant grows natively in the ground, and to propagate it, and protect the areas where it can thrive. As for how, see [sea slugs](https://www.treehugger.com/sea-slug-lives-like-a-plant-by-stealing-dna-from-algae-and-using-it-4862713#:%7E:text=It%20turns%20out%20that%20the,it%20needs%20from%20the%20sun.). There are already actual animals that can absorb plant matter, feed it from their cells, and absorb the energy it produces. Some species can actually live without eating any more than their first few mouthfuls of algae. I doubt that a bulb that would fit on a person's head would provide enough chlorophyll for this, but it could make their need for food much less. And again, if this bulb has the power to hasten growth in other plants, it wouldn't need to be directly beneficial to the host organism to be a beneficial arrangement overall. Why the head? The head has a high supply of blood, but unlike other places with a high supply of blood (hands, feet) a bulb would not be in the way on the head. It doesn't interfere with clothing, tools, or other things. Perhaps the graft is done when the bulb and the girl are both young and small, and they grow together. Maybe they don't all take and you end up with pariahs who couldn't graft a bulb. [Answer] Actually the "bulb" is not a dormant bulb as such but the bulbous base of a parasitic plant where it stores chemicals and nutrients it produces. Some plant species tend to trail leafy tendrils that the humanoids find aesthetically pleasing. The plant originates from spores or seeds embedded in the scalp - possibly ground in by head-baskets women used to carry goods and heavy loads before the plants arrived. To survive, the plants do need access to sunlight, so the top of the head makes perfect sense. The plant is symbiotic by way of the chemicals it introduces into the body of its host - sufficiently beneficial to the host that they would prefer to both accept the plant on their head and keep it there. There are a range of types of effects and benefits to choose from such as elevated stamina and other mental and physical benefits. Toxic hallucinogenic poisoning is probably not a good reason. Providing the host with essential fatty acids the host can't produce might be. From the plant's perspective, the chemicals it produces originally evolved to prevent stinging sensations its presence would otherwise cause and evolution took it further. In return the plant receives trace nutrients it has lost or never had the ability to produce from the humanoid scalp, and has evolved to produce sufficient rootlets to maintain stability on the head without endangering the host. Plant favoring the chemistry of premenopausal women could account for why children and men rarely if ever get infected - or it could be something else entirely such as cultural choice. The plant can be destroyed by chemicals such as acidic fruits or vinegar or harsh skin peeling agents - and are destroyed if they establish themselves in an unsightly or unwanted manner. The powder originates from the plant shedding the "bark" or outer layer of its base, which has magical properties when used horticulturally. Women may also cut the plant to harvest crystalized sap from the plant as well. How well this fits into your concepts and the cultural practices of the humanoid society is all part of the story! [Answer] Evolution You ask why as symbiotic plant might decide to evolve to survive on a persons head? Evolution. Firstly, if it attached it self almost anywhere else on a person, before they realize the benefits, you might just chop of the limb or would be more open to risky surgery to have it removed. It would also be more likely to get in the way if its on a arm or leg and thus get knocked off during daily life. But attached to someones head? No one's chopping your head off (unless they really don't like the plant), surgery to remove it would be much more dangerous and likely to kill the host so people may not attempt it (at least after the first few failures). While it is vulnerable on someones head, I would argue that most people will do almost anything to avoid being hit in the head. Someone throwing a punch at my head? I'm either putting some other part of my body in the way or moving away from getting hit, I'm very much not however going try to "take the hit" with my head. ]
[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/217657/edit). Closed 2 years ago. The community reviewed whether to reopen this question 2 years ago and left it closed: > > Original close reason(s) were not resolved > > > [Improve this question](/posts/217657/edit) In my D&D game, the spell wish doesn't work after you cast it a certain amount of times. The relevant portion of the wish description (emphasis mine): > > Finally, there is a 33 percent chance that you are unable to cast wish ever again if you suffer this Stress. > > > # Magic 101 ## Mana Imagine an ocean, infinitely big, that exists above the Material Plane. That ocean is the Weave, and it is full of magic. That ocean has a thousands of little streams of magic, called Souls, that connects every living being to the Weave. The Weave is too far away for any mortal being too use, but the Soul is easily accessible. When a person uses magic, they draw on the power of the Soul. Powerful wizards have essentially widened their Soul by using so much magic it erodes the "riverbank", and as such can use much more magic in their souls. ## Essence Essence is what the universe thinks of you; what YOU are. Imagine a paragraph, that describes every facet of who you are. What you think, how you look, everything. Using powerful magic, you can change something's essence. The more you change something's essence, the more Mana it requires. ## Casting When you cast a spell, you draw on the power of your Soul in order to change the universe. The larger the change, the more magic it requires, and so people's magical ability is limited by the power of their soul. # How Wish Works When you cast Wish, you create essentially an incredibly powerful transmitter, which sends a signal to the Weave. This signal tells the Weave what you want it to do, and as such Wish can do incredibly powerful magic. # My question is: Why can't you keep casting Wish [Answer] # The wish alters the Wizard's Essence: Normally, spells are under control of the wizard casting them. The wish is pure fulfillment of desire, which is shaped not by the wizard, but directly by the weave. It's a massive rush of raw energy (like overclocking). Normally, the soul has a certain amount of flexibility to "expand" to deal with a short-term rush of energy. Repeated flexing expands the capacity of the soul. To handle this massive rush, the wizard's soul has to have it's essence changed. Each time you use a wish, those "eroding banks" of the soul risk being completely washed away. The wish (controlled by the weave), on the fly, adjusts the essence of the soul to preserve the soul. After all, the weave/wish assumes the wizard doesn't want to die or destroy their soul, right? But remaking the soul to survive the rush of the wish in such a manner permanently alters the essence of the soul to make it less compatible with such surges of power. Each wish is more likely to change the soul to be permanently "fixed" so the wizard can no longer channel that large of an excess of magic out of self preservation. The soul can still flex, but the soul's upper limit of flexing is permanently reduced, and the soul no longer is compatible with further wishes. [Answer] The real reason: wish is absolutely powerful and being able to cast it too often and with no risks would give any caster that knows it the power to become borderline divine in terms of power. The reason as you're asking it: let's picture the act of using magic as a [Japanese goldfish scooping game](http://yabai.com/p/4272): Before I continue, just to clarify, the game is essentially about scooping goldfish from a tank into a bowl of water using a scooper with a piece of thin paper that serves as a net, the player must be careful not to rip the paper and must scoop as many goldfish as possible. With that explained, instead picture the weave not as an ocean, but as the fish tank, filled with various fish of different shapes and sizes. When casting a spell, it's as if the wizard's soul acted as the paper scooper, scooping a fish equivalent to the spell they want to cast. This comparison also explains why wizards can only cast so many spells depending on level, as they level up, it's as if their souls became the equivalent of a better scooper with thicker paper, capable of getting bigger fish and taking more punishment until it rips and you have to stop to fix it, also known as a long rest. Now, smaller and slower fish (spells) are easy to catch and put little stress on the wizard's scooper (or soul power) even at low levels, and thus can often be cast without risk. Now things like wish,those aren't as easy. Wish is a 9th level spell, a type of spell so powerful it can bend reality itself to a much larger degree than, say, summoning magic missiles from thin air. If a 1st level spell is a small goldfish and a 9th level spell is almost the size of a sardine, wish is almost like trying to get a catfish with that same scooper of yours. It's tough, it takes a lot of effort just to pull it off and chances are that if you're not careful and try to get a fish that's too big (aka try to create a larger effect through the spell, say get a perfect duplicate of the [wand of Orcus](https://forgottenrealms.fandom.com/wiki/Wand_of_Orcus) completely loyal to you and just as powerful), you risk permanently damaging your "scooper", and unlike the paper net, the scooper can't be replaced or fixed through resting, no matter for how long. It still works for the smaller fish and sardines, but for the heavy wish? It just can't, your subconscious prevents you from doing so, as even attempting to cast it again would require your soul to use more power than it can actually deliver, or in your own example, you'd leave your transmitter broken beyond repair, which would at best cause you to die and at worst could destroy your very soul as it twists itself apart like a muscle torn from flexing beyond what it could ever handle. [Answer] Musicians disease There is a little known and rare phenomenon that can start with people practicing again and again. They are often in the top of their fields and often in music. Then one day, seemingly out if the blue, they can't. Their muscles lock up because all their neural pathways suddenly only generate garbage. Why this happens is unknown. The best guess is that the neural pathways for this particular activity are improved to such extent with myelin and the like that something goes wrong. Maybe it's a bit like stress and these particular neurons suffer a burn out. It is still undecided. What we do know is that they can't do it anymore. Your magic can be the same. A wish takes practice and power. Even in a short time it can take so much of a person, there's an average chance of 33% that someone just loses their ability to draw the power. Like a burn out, the stress is too much on the magic pathways. Their improvements to the magic channels too much, so something goes wrong. Or in your own vernacular: the riverbank has eroded too much. This damage has caused it to now flow differently, leading to the loss of magic. Like a river suddenly finding a path around a lake, as it eroded a hill to a different valley. [Answer] You're using your own lore in combination with a mechanical feature. Sure, the Weave exists as lore in d&d, but you've got your own spin on it. Nothing wrong with that. But very simply, the answer is that you can do whatever you want, since you're making the rules. Anything answered here is merely suggestion and/or brainstorming. The easiest explanation is that Wish, fundamentally, is the most raw form of magic, using your will to cause any change. As such, you're putting your will ("soul", or otherwise) "on the line", attempting to bend the Weave with it. However, the strain has the potential to be too great, causing your will to be what bends (or even breaks). Not so much that your soul is destroyed, but it's "fractured". Similar to being unable to use a broken limb: you technically could use the limb (for minor functionality, perhaps), but it simply can't function past a certain point without suffering greater damage or destruction. Another way to think of it would be trying to use wood to warp metal. Depending on the degree/strength of the metal, the wood could possibly do it. But if the wood (the caster) tries to bend metal beyond its ability (the strain of Wish is too great), the wood could crack, being unable to attempt to bend any metal without risk of snapping entirely. Other options similarly exist. If it's more in line with your world's lore, Wish need not have that caveat; it could be that people have no risk of being unable to ever cast Wish again. It would have implications, for sure, but any ruling is valid if the GM and players accept it. (Note: rules as written, Wish doesn't carry the aforementioned risk at all if being used to replicate an 8th level spell or lower. Only wishing for something outside the bounds of a spell carries such risk of being unable to cast it again) Ultimately, it's up to you as to how you handle the situation. If I had the lore you stated and decided to keep Wish ruled as written, my previous idea is what I'd personally go with. [Answer] Soul is yours. Weave is not yours. Your soul is going to do magic for you. It is an organ like your kidney. The kidney is going to make pee for you. The soul is going to do magic for you. The Weave though is something else. It is not you, or yours. It is like a huge gentle dog that you have never met. This huge dog likes people and usually it will go along with requests even from strangers. But you can piss it off if you bug it and bug it. It will start to wonder "who the heck is this, bugging me so much?" Then it will not go along. It might decide it does not like you. That can mean trouble from a huge dog. The Weave is much, much bigger than that. [Answer] # It started with a noble cause "Wishing" is an abomination, replacing organic reality with synthetic artificial plot. Magic is full of abominations, from truth-sayers to oath-enforcing gadgets to undead things and automatons. A better world might have abolished it altogether. In yours, there was a small rebel group of mages (that is, two mages) who wanted to help the environment. The first wished that wishes would never come true and vanished in a puff of logic. After failing to wish the first one back, the second wished that half of wishes wouldn't come true, but his wish didn't come true. So he wished that in a third of the cases, any given person's wishes would never come true. Maybe he could have worded it better, but he was unlucky on the first draw with that one and that's what you're stuck with. [Answer] It's purely meta and for game balance, but there's one property that would be violated in universe just as much as outside. That's coherence. At some point, if wishes are unlimited, the universe gets incoherent. Maybe there's directly contradictory wishes, maybe there's 100 that all need to be balanced. The Weave either developed, or survived due to having to begin with, or intrinsically has as a Platonic object, or was given by the Overfather, defences against too many wishes. That's necessary both in universe, and outside, where some poor DM actually wants the game to have a comprehensible plot. ]
[Question] [ I‚Äôm thinking of making airships and zeppelins very commonly used (for cool factor) in my pseudo-mid-20th-century novel, which takes place on Earth in the very far future, tens of thousands of years after most of modern humanity has abandoned the planet. Many of the circumstances that allow this setting to exist can be handwaved for now, but among other things, I want to explain where this new humanity gets all their helium, especially since we‚Äôre already running out of natural helium in the present. Is hydrogen fusion byproduct a plausible source of helium for a humanity living among these technological ruins? Would there be a reason for the helium to be stored in the first place, and could it last several millennia? [Answer] There wouldn‚Äôt be enough helium produced. Fusion of hydrogen to helium releases about 0.645% of the mass as energy ‚Äî let‚Äôs call it 1% for a back-of-the envelope calculation. Global energy consumption is around 100,000 TWh ‚Äî let‚Äôs say that cheap fusion would increase that, and call it a million TWh. That‚Äôs 3.6E21J. Dividing by the square of the speed of light (9E16), that‚Äôs a mass of 40 tons converted to energy per year, which would produce 4,000 tons of helium per year. Filling one Hindenburg-sized airship once needs about 20 tons. So even if a thousand years‚Äô worth of fusion by-product was still lying around (it wouldn‚Äôt be), you could fill 200,000 airships and then you‚Äôd run out. That‚Äôs quite a large number, but nowhere near enough to sustain global commercial aviation for the long term. [Answer] No, it wouldn't last for millennia. First of all, helium has very small molecules and it leaks from any container holding it. It is actually used to leak test vacuum connections, because it goes easily through any opening. Therefore no container can reasonably store helium for millennia. And, to complete the picture, Earth's gravity is not enough to hold helium with the current temperatures. All the helium would escape Earth's gravity well and go into outer space, as it happens with any helium we vent today. [Answer] Helium is in fact a renewable resource. The radioactive atoms (uranium and thorium) underground slowly decay by emitting alpha particles (helium nuclei) and the helium slowly seeps out. It is very good at seeping out. When a combination of conditions is met, a (relatively) gas-tight dome forms underground and gases (helium, methane and friends) build up in the rocks under the dome. And there is a catch: we don't know all the mechanisms of methane formation underground so we don't know if it does replenish itself, but we pretty much know about helium - it is a radioactive decay product. You wait - and your depleted helium rich natural gas deposit has pressure again and is even more helium rich, because the helium producing isotopes are long-lived (they half-decay in bilions of years). On the other hand, it looks unlikely that the future nuclear-fusion using people will even try to store waste helium underground. First, it is environmentally absolutely safe and second, the reactors will probably not produce much of it anyway (you get a great deal of energy by producing a miniscule amounts of helium). This is why underground storage efforts like those proposed for CO2 are unlikely. [Answer] [Humanity currently produces 140 million cubic meters of Helium](https://www.statista.com/statistics/925214/helium-production-worldwide-by-country/). Each cubic meter is about 180 grams, so that comes to 25k tonnes per year. Using the Kardashev scale, I'll assume a K1 civilization powered by fusion on the Earth. This civilization has to either build massive radiators, or dump heat in the planet core, to avoid boiling the surface. Going much beyond K1 is going to require even more exotic solutions. A K1 civilization in that sense has 2\10^17 Watts of power, which is 6 \ 10^24 J/year. D-T fusion to produce He is 0.645% efficient. So for every J of energy produce, 1/0.00645 J = 155 J of He is produced. This means 6 \* 10^24 J of energy produces 9 \* 10^26 J of Helium. Divide by c^2 to get mass gives us 10^10 kg, or 10^7 Tonnes (10 million tonnes) of Helium produced per year. Earth's atmosphere is 10^18 kg. If a civilization that lasted 100,000 years produced that much Helium per year, that would be 10^15 kg of Helium. The current atmosphere is 5 ppm, 3 \* 10^23 helium atoms leak out of it per second. I'll assume this rate varies linearly with Helium concentration in the atmosphere. Earth's atmosphere is about 10^44 molecules. At 5 ppm, there are 5\*10^38 Helium atoms in the atmosphere, of which about 6 in 10^16 leak out per year. If you mass produced Helium (like above), you'd lose only a tiny fraction of it over a non-geological time period, at least until your Helium changed the thermodynamics of the Earth's atmosphere. So, a 100,000 year long fusion powered K1 civilization that had massive heat pumps that dumped heat in the Earth's core would leave the Earth's atmosphere with about 0.1% Helium by mass, and that amount would last over relatively long periods of time; I think the sun would swallow the Earth first. At 0.1% Helium, I could imagine it being economical to harvest it. Going a step further, one could imagine the buried fusion reactors still running, and venting Helium to the surface in certain areas. Now, such a technology level is quite ridiculous. [Answer] Helium has many applications. If it were cheaper it would be quickly used in other ways, it is unlikely that it would be left to the future generations. Even if some technological advances reduced helium uses in some fields the use would increase in other fields. For example lets imagine that a new superconducting material allows to build powerful magnets at the temperature of liquid nitrogen, that would cut the annual demand for helium by a third, at that point it could become so cheap that the use of helium as inert atmosphere in many industrial processes would quickly grow and swallow the extra production. ]
[Question] [ This isn't a question about an anatomically correct centaur and its features, but I will assume general characteristics of a centaur and the objective is to find what environment would allow an ancestral hexapod to evolve until acquiring said characteristics. This is a way to explain the presence of centaurs. I will not focus on the absolute origin of these hexapods. This question arises from the fact that I was unable to think about an adaptive motif to an environment in which a centauroid creature could evolve. Considering the principal features, humanoid torso over a horselike body. A horselike body indicates highly cursorial habits, with massive lungs to permit powerful races and unguligrade legs with just one hoof, while the humanoid torso has an erected section of the spine exactly over which the horse's neck and head would be, having two long arms with a high mobility range and manipulator hands on them, indicating arboreal habits or that he has to stretch its arms over its head to reach its food. What I mean by this is that it seems that a creature as similar as possible to a centaur could not evolve naturally, without magic and without things like genetic modifications, since its characteristics seem mutually exclusive or only useful in very different environments (possibly jungle and plains, respectively). I have tried to find my own justifications but I am not really convinced. For example, a herbivorous animal that needs to evolve in order to reach its food in the crowns of the not-so-scarce but not-so-abundant trees in a savanna; maybe this creature would need to search on the trees, but in this case it's more probable for it to just evolve as a hexapod giraffe, just lengthening its neck. So the question is, what environmental pressures will lead an ancestral hexapod to evolve into a "centauroid"? To consider, the ancestral hexapod could be just a primitive mammal but with six limbs, but at the discretion of whoever provides an answer, this creature could change if it considers it so. [Answer] There is one kind of creature that already has four legs and two arms: the praying mantis. Now let's think of a place with large bugs: Australia. In a continent where [spiders eat birds](https://en.wikipedia.org/wiki/Goliath_birdeater) and [centipedes eat bats and snakes](https://en.wikipedia.org/wiki/Scolopendra#Ecology), it would be very advantageous for a mantis to be really big as well. In such an arms race for size, without human interference and given a few more hundred millions of years, Australian bugs might start evolving more specialized respiratory and circulatory systems to beat the the Square Cube law. I have already provided an extensive answer on [how spiders could do so in order to become driders for an older question](https://worldbuilding.stackexchange.com/a/52163/21222). In this case here, mantises might develop book lungs like that of arachnids, then as they grow in size through the aeons they could develop actual lungs. They might also evolve to have an internal chitin skeleton, and lose a lot of chitin outside, otherwise they will be [seriously impaired](https://worldbuilding.stackexchange.com/a/112218/21222) and [slow and not very mobile](https://worldbuilding.stackexchange.com/a/112303/21222). At some point in evolution they will be too heavy to fly, so they will lose their wings. They will compensate by becoming runners, so their legs will evolve to be like those of a horse, chitin hooves and all. And since they will no longer prey by ambush, but rather by run-and-disembowel-the-target, their eyes will become front facing. Over time they might develop larger brains, and with that the ability to make tools. At this point making better tools is a selective ability, so their current arms will trend to develop towards a more handy shape (drumroll). So there you have it. Your reallistic centaur is not a charming horse person frolicking in some European grove and dancing with the pixies, but rather a lovecraftian, crickety piece of nightmare fuel running around and hand-goring emus in the Aussie deserts. [Answer] ## Elephants and gazelle give you an answer Human arms are actually quite different from their climbing ancestors, so there is no reason they have to have been used for climbing. your creature could simply evolve the human like arms from a less used limb. the arms would be used ot grasp and collect food. we already see a similar model today, elephants, a grasping "limb" on a quadrupedal frame. they use the trunk to bring food to the mouth, just like humans. an elephant without a trunk can access very little food and would not survive. You also have animals that use their front limbs to pull food to the mouth, outside primates like this Gerenuk, the front limbs are even adapted to grasp , although they also have to double duty as hoofed feet, your front feet will not have that problem and can be fully adapted just for grasping and food acquisition. [![enter image description here](https://i.stack.imgur.com/D7Tnw.jpg)](https://i.stack.imgur.com/D7Tnw.jpg) You will have to ask yourself what the front limbs were used for before but they could have been very different creatures then. Early horse (eohippus) feet are far more similar to primate feet. If you want to give a nod to this give your centaurs 4 fingered hands instead of 5. you could have started with a 6 limbed [Eohippus](https://en.wikipedia.org/wiki/Eohippus) and while the 4 hind legs became cursorily adapted the front two became grasping adapted for pulling food to the mouth. [![enter image description here](https://i.stack.imgur.com/XceiV.png)](https://i.stack.imgur.com/XceiV.png) ## Keep in mind you have a lot of other anatomy questions you have to solve for a centaur For one, where are the lungs in your creature? If it is in the horse part what is in the rib cage human part? the human part does not have enough room for big enough lungs. You will also have a hard time getting enough food through a human mouth to feed a horse sized body. You may want to use something more like the horses around during the origin of the centaur myths, which was significantly smaller than modern horses. Think more pony sized. You also need some really strong tendons to hold the human torso up, the human torso should not suddenly stick out, there should be a big hump of muscle holding it up. [Answer] I think the most likely ancestor for an hexapod should be a crustacean like a crab: they already have more than 4 limbs and already live at the border between water and land. Moving to a more dry-land type of life, they would evolve lungs and all the other shenanigans, reducing their limbs to six in the process. From there they could use the rear 4 for locomotion and the front 2 for manipulation, think for something like grabbing food which grows above ground level. Consequently the most likely environment where such a body plan seems to be useful would be a place with sparse vegetation and tall trees/bushes. [Answer] I can immagin a savana with some higher trees with very delicios fruits. Start with a six legged rabit thing. He runns around, eats roots, and (not like a rabbit) insekts. There are a lot of threats around. Rabbits sit often on there rear legs and try to get there head as high as possible to look around. our six legged friend can do the same, even while walking. When he becomes better in looking around, while runnigng, he will survive more hunter attacs. he lears to grab insekts and nuts for eating and he becomes bigger to reach more nuts and fruits on the lowest parts of the tree. Food is rare, and he needs to walk long distances each day for food. he becomes even bigger and develpops horn ond his 4 Legs. the 2 front legs are used only someties for grabbing. (like apes) Than he starts using rocks to kill smaler animals. His hands develop know and he becomes more and more to a hunter. The eys move from the side to the front. And there you have the lucy of centaurs. But i have no idea, how they get humenlike heads, when there evovle humans in the same world. that would be a to big coinsidence [Answer] # Same as Humans The only real way I can think of to get a human-like body is as a brachiator. The centauroid form seems like a natural result of a brachiator adapting to the plains like humans did: It'd start with the 4 legs clustered around the lower part, before the hindlegs would extend outwards so that the back can help push off when running ]
[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/194806/edit). Closed 2 years ago. [Improve this question](/posts/194806/edit) I am just curious what would happen to those poor souls whom are thrown overboard while the spaceship which is enveloped in a warp bubble, does the bubble acts like a firewall similar to the black hole version that destroy entropy or do these unfortunate cast away simply found themselves drifting somewhere at the current velocity of the spaceship while their blood boils off. The warp drive aka Alcubierre drive is powered by a highly classified exotic matter field generator which distort the space around the spaceship forming what's look like a bubble, analogous to crumbling a piece of paper into a ball smearing the wet ink all over the paper. P.S: as usually you all know the drills so don't hesitate to highlight my mistakes just let it rip Yee Haw! [Answer] ### Their body will be converted to a multi light year long skid mark The poor soul doesnt intersect the warp bubble every molecule at once. It takes time for the body to transition that threshold out of warp, and during that time, the ship moves significant distance. Two molecules of the body which were adjacent in the warp bubble are now hundreds of km apart as they passed the bubble picoseconds apart. The body will be distributed as individual molecules scattered over the route of the ship. A 2m tall human passing headfirst through the warp bubble at 1cm/second will take 200 seconds to pass through. If the ship is travelling at 72 lightyears per hour the body will be distributed over a 4 ly region. They've become a giant cosmic skid mark. [Answer] If I have to draw an analogy with what happens to bodies being thrown off a fast running train, fast running cars/trucks, fast running boats and fast flying airplanes, the impact with some interface in the medium where the thing is travelling won't be pacific (air/ground, air/water, moving air/still air). It usually involves some tumbling and rolling followed by physical damages and/or dismembering, due the inflexibility of nature in applying conservation of momentum and energy. I expect something similar also in this case: once the body reaches the interface between the warp bubble and the space it will start bouncing around before it can be left exit the bubble. Though I wonder if it can leave the bubble at all, considering that nobody has ever complained about a warp bubble leaving its ship behind... In any case, being in the vacuum of space means that we won't be able to ever listen to a first hand report of the experience. The subject will probably die of space exposure before reaching the interface. ]
[Question] [ "If you shine a low-pressure sodium lamp on a yellow sodium flame, the flame will be black." I shamelessly stole the above text from somewhere but it whetted my curiosity. I am wondering if out there in the universe there is a similar condition where a star's emissions could mimic the sodium lamp and a planet could have black lightning storms? [Answer] This is what [you are quoting](https://geekologie.com/2018/11/sorcery-guy-produces-black-fire-that-cas.php) [![enter image description here](https://i.stack.imgur.com/Fp9Eo.png)](https://i.stack.imgur.com/Fp9Eo.png) [How does it work](https://sciencenotes.org/how-to-make-black-fire/)? > > Flames emits light and heat, so it seems impossible to make black fire. However, you actually can make black fire by controlling the wavelengths of absorbed and emitted light. > > > The low-pressure sodium lamp has the same spectral signature as the sodium-tinted flame. When you add sodium (from salt) to the flame, the sodium atoms absorb the light from the lamp because it’s exactly the energy they need. What happens when you absorb all the light? You see black. > > > Now to your question > > I am wondering if out there in the universe there is a similar condition whereby a star mimic the sodium lamp and a planet can have black lightning storm? > > > The problem is that no star has a narrow emission spectrum as a sodium light. As a consequence you won't see the black lightning because there would be other frequencies which would not be absorbed (same reason why a sodium flame doesn't appear black under sunlight). For comparison, this is the [emission spectrum of a low pressure sodium lamp](https://commons.wikimedia.org/wiki/File:Low-pressure_sodium_lamp_spectrum.svg) [![low pressure sodium lamp spectrum](https://i.stack.imgur.com/o5f4n.png)](https://i.stack.imgur.com/o5f4n.png) while this is the [solar spectrum](https://www.esa.int/ESA_Multimedia/Images/2017/12/Solar_spectrum) (note the scale of the x axis) [![solar spectrum](https://i.stack.imgur.com/pY3mF.png)](https://i.stack.imgur.com/pY3mF.png) [Answer] L Dutch's answer is correct - this wont happen under current physics. Lightning emits light, black is the absence of light. Aside from the comic book character and associated TV show, "Black Lightning" can't exit in the world as physics as we understand them. But I'm 100% confident we don't know all the laws of physics yet; physicists are still learning things and will be for hundreds of years at least; so you need to delve into the realm of unobtainium, handwavium, magic, or "unspecified future knowledge" in order to explain your black lightning. Some ideas: * Something in the atmosphere that goes opaque black briefly when a lightning bolt passes (say, due to the high voltage). The unknown substance desolidifies soon after the bolt passes, but before heating up itself to black body levels. * Something in the atmosphere that absorbs visible light and emits, say UV, in an exponential curve - like an automatic tinting window - normal conditions its unnoticed, maybe a slight shade in midday sun. Lightning strikes and its outline is stencilled out of the sky. * The eyes observing it are digital, when looking directly at lightning, they suffer integer overflow for those pixels brightness levels, wrapping the high number back around to 0, and report the lightning to the brain as black. * Special kind of static electricity: (Insert technobable). Therefore sparks are black. Therefore lightning is black. ]
[Question] [ Besides the obvious steel entry doors, I am most concerned about air-inlets and exhausts. Electricity for essential things like lighting, ventilation or pumping water is generated by diesel generators. These must have an exhaust somewhere. Wouldn't it be obvious for the enemies to find the spot where exhaust fumes come out of the ground? What's to keep them from pouring some cement down that hole? While we are on in, if this is in a sparsely populated area, would it be sensible to instruct enemy soldiers to shove some dirt into any unknown pipe sticking out from the ground, blocking potential intakes? [Answer] ## Hide from what, exactly? In and beyond the WWII timeframe, there were different kinds of hidden bunkers. * Hide from long-range reconnaissance and attack. The idea with these bunkers is to stay hidden from enemy (photo) recon aircraft and bombs. In WWII, examples include [B8 Bergkristall](https://en.wikipedia.org/wiki/Gusen_concentration_camp#Aircraft_production), an underground factory dug by concentration camp prisoners to build jet aircraft. After WWII, with a completely different purpose, think of the bunker under the [Greenbrier](https://en.wikipedia.org/wiki/The_Greenbrier#The_Bunker) hotel. These are not supposed to survive with enemy troops camped on top, instead the idea was to defeat the sensors and weapons of the time. * Camouflaged fighting positions. Some smaller installations were supposed to remain secure from attack by nearby enemy forces. Being camouflaged into the landscape helped, but often the site was also supposed to fight. Hiding completely would defeat the purpose. An example would be the [Maginot](https://commons.wikimedia.org/wiki/File:Maginot3ix.jpg) fortifications in France or the Swiss [reduit](https://commons.wikimedia.org/wiki/File:Panzerturm.jpg). Again, the bunkers were not supposed to remain hidden with enemies directly on top, but here the camouflage was supposed to complicate attack by nearby troops. * Hide from close search That's what you are looking for, right? These were quite unusual. I can think of two interesting British examples. One is the bunker for [Operation Tracer](https://en.wikipedia.org/wiki/Operation_Tracer), the plan to hide a few observers on Gibraltar if the Germans or the Spanish ever took "the Rock." The other are the bunkers of the [Auxiliary Units](https://en.wikipedia.org/wiki/Auxiliary_Units#Operational_Patrols), constructed in the UK in case the Germans invaded. Neither one had to be used in action. As you can see, the larger the installation, the less likely it was to remain hidden with enemies directly on top. The smaller ones would rely on being quiet, and having their air pipes, exhausts, etc. in places where the enemy would not search. [Answer] ## The Art of Concealment: Are you trying to hide one from random guys, or people seeking out bunkers? A lot of effort went into this kind of physical secrecy in WWII, more than I can even reasonably discuss. You'll need to do some research to get a good feel for it. But remember this is a major war zone, and there is a lot of stuff sitting around. Abandoned buildings, abandoned wells, destroyed vehicles, etc. mean it's a complex environment to be randomly pouring cement or dropping grenades at everything you can possibly imagine as a bunker. A large pile of brush is semi-impassible and fairly easily allows air exchange. A pipe amidst one would be easily overlooked. How about a pipe made to look like a dead tree trunk (complete with open top or large 'rotten' holes? Make it look partly burnt, and a casual observer might not realize smoke wasn't from the tree burning (a smart one would tell by the smell...). A 'rock' made of concrete would only be obvious up-close, and might just seem like someone poured out excess concrete in a pile. A pile of rocks might be big enough to allow air exchange around the rocks. Then there's the hidden in plain sight stuff. Decorative brick work with openings might not be noticed as an air intake. Or maybe it's the intake for the building it's next to, not a bunker. And why not just fix a smokestack into an actual smokestack of a surface building? I have this picture in my mind of a cabin in the woods with an elderly couple living there, and there always seems to be smoke coming out all the time. An old boarded-up well house without a roof is an air intake, and if you break into it, why there's just a hole in there going down. The point is, there are as many ways to conceal these things as there are clever people. In most urban environments, most people don't know what every little thing is, and aren't going to be randomly blowing up EVERYTHING unless they are true vandals or are systematically rooting out bunkers. In rural areas, distance and relative lack of reason to suspect bunkers will make finding them unlikely. Bunkers are hard to make, and they usually had a special reason to make one. Most weren't intended to be concealed, but instead to protect from bombing. So if the enemy controls an area, they'll eventually find a large bunker in operation - the bunker would need regular supplies in any case, so it would be eventually moot. If not, you would have either no reason to look, or be too occupied fighting the guys in front of you and not worrying about a possible secret bunker. [Answer] Bunkers were mostly just armored, not hidden. Typically without even a door, as by the time the enemy has reached that far, a mere steel door will barely slow them down much less stop them. But let's consider the case of a hidden bunker that is not just a tunnel system such as was very common in Vietnam. These bunkers are huge, and have hundreds of meters of tunnels. There is no reason for the air intake and exhaust to be anywhere near the main complex, they can be many hundreds of meters away, and disguised as other entryways into the ground. Storms drains, water well, etc. You could reroute the exhaust vent through the apparent chimney of a house out of sight from the bunker location. Even if the house is seen, the presence of smoke from a chimney will not be unusual. Being well off the ground as a chimney should be, there is not reason for the different smoke composition to be smelled from the ground. Any diesel exhaust can easily be filtered through a basic carbon filter to remove particulates and smell, then run through a bit of water to cool it down, leaving the exhaust appearing as mere cold air from some foul cave. NO, with even a modicum of effort the air and exhaust from a hidden bunker can be disguised quite well. The same for water source and effluent. (can be stored, if need be). What is more likely to give away a bunker's location are the access roads that were used to construct the bunker, drive away the dug out earth, and bring in supplies and personnel. And while those cannot be hidden well, as it is very hard to tracelessly vanish a road, they can be trivially disguised as roads leading elsewhere. If you need to discover a hidden bunker, you need to go high-tech, or patient. Patience, because inevitably at some point today, or tomorrow, or next week or next month people will enter and exit. Or high tech, if you are in a hurry. Thermal imaging, as any operating bunker will cause a hot spot in the ground around it. Or a ground microphone network, which will detect any operating engines, machinery, or clumsy humans inside your bunker. Hidden bunkers are hard to find, that is why there were still dozens of abandoned WW2 style German bunkers being discovered all over Europe, decades after the war. And some manned Japanese bunkers that were not discovered until several years after the war! Seems they did not quite get the message that the war was over. [Answer] Exhaust fumes or lack of ventilation are unhealthy, but more unhealthy, to the point of lethal, is a bullet in the head/body. I think you are not interpreting the circumstances in the right way. First of all, soldiers fighting to get control of an area bring with them weapons and rations, not cement. Then, preparing cement requires time for the dry powder to be mixed with water and then poured into the suspected hole. And while doing so, what do you expect, that nobody will shot at the cement mixing guys, just because they are indulging in masonry, not war? Then, even if they somehow managed to clog the one pipe they found, the baddies behind it would still be alive, armed and hidden, ready to shot at whoever has had fun tampering with their lungs. And maybe they placed the holes in sight of their bunker, just to be sure to get a good sight on the pranksters. Top this with the obvious countermeasure of creating a lot of dummy ventilation holes, and draw your conclusions: do you better go hunting for the bunker, or do you prefer jamming grenades into holes scattered around a place stuffed with armed soldiers? [Answer] Even sparsely populated areas have some population, which will typically live on roads, which are the logical paths of advance for an enemy force. So you can camouflage small bunkers as farm buildings and similar in the small towns along these roads. Case in point: [Constance](https://en.wikipedia.org/wiki/Konstanz) is a German town that straddles the river Rhine, which along most of its course forms the border to Switzerland. Thus, it forms a natural bridgehead. And during the years before and during World War II, the Swiss were somewhat apprehensive about the Germans invading from this bridgehead. So they encircled it with a ring of infantry bunkers to at least slow the potential German advance. Most of these bunkers are still standing (because they are very well built - the Swiss are good at building for eternity - and correspondingly hard to dismantle). The [Verein Festungsgürtel (site only in German)](https://www.festungsguertel.ch/) shows these bunkers on a map, and has hiking suggestions. And there are indeed a number of bunkers that were indeed camouflaged as farm buildings, like [this one](https://www.festungsguertel.ch/application/files/1415/5082/4145/A5633_Triboltingen_sued.pdf) in picturesque [Triboltingen](https://en.wikipedia.org/wiki/Triboltingen), right on the main street. The description says (my translation): > > The infantry bunker, camouflaged as a stone building, is integrated into the town center of Triboltingen. The polygonal "fighting room" was prepared for an infantry gun, a machine gun on a fixed carriage and one observer. The entryway is angled, and the top floor can be reached through an exterior stairway. In the basement, there is a living/sleeping area without an emergency exit. > > > Edit- here is a nice short YouTube video on the analogue WW2 period bunkers guarding the road from France into Switzerland near Geneva: [The Lovely Swiss Villas That Could Destroy An Army](https://youtu.be/tPL9-L2gwzo). ]
[Question] [ I have this Earth-like planet that is running short on materials, like minerals and gasses, and they have a big spaceship that is able to gather materials from a gas giant that orbits the same star the planet does. What materials might the planet need that a gas giant could be realistically made of? I am no expert, thus I'm asking, but I know that for an atmosphere to be breathable you need at least Nitrogen and Oxygen and that the gas giants in the Solar System are mainly made of Hydrogen (please correct me if i'm wrong). Now, it doesn't necessarily need to be a gas giant, but it must be at least a planet made of something the main planet is needing, like solid nitrogen that once melted gets pumped into the atmosphere, but is that even possible? What materials might a planet in a super distant future need for its own survival? [Answer] [Helium-3.](https://en.wikipedia.org/wiki/Helium-3) Helium 3, or Trialphium, is the lighter, rarer stable isotope of helium that is often suggested as a fuel source for advanced fusion plants, because Deuterium-Trialphium fusion is [aneutronic](https://en.wikipedia.org/wiki/Aneutronic_fusion), so the reactor housing doesn't need to deal with neutron irradiation the way that the lower-temperature Deuterium-Tritium fusion does, and the charged particles produced by D-3He fusion are easier to convert directly to electrical power. As a light, non-reactive gas, Helium-3 is generally rarer on Earth than in other parts of the solar system, -- monatomic helium tends to escape from the atmosphere of Earth over geologic timescales, and unlike Helium-4, which can be replenished from radioactive decay, Earth's Helium-3 is primordial, and potential replenishment from the Solar Wind is typically stopped by the Earth's atmosphere and magnetosphere. As a result the fraction of available Helium that's 3He is lower on Earth than in other solar system bodies. In a high-tech, long-lived civilization, it may initially be feasible to obtain Solar-wind-deposited-Helium-3 from strip-mining the surface of their moons, but ultimately, if they have a light nearby gas giant like a Saturn or so, and decent in-system spacefaring technology, obtaining it from the upper atmosphere may be more economical. [Answer] Helium Helium has an influx from the Earth crust into the athmosphere. From there it eventually escapes into space. See [Can helium disappear from Earth?](https://physics.stackexchange.com/questions/78586/can-helium-disappear-from-earth) In the case of your planet that has already happened. Either their crust emitted less helium or more escaped anyway they ran out of it. Some people may think it is important just for baloons and talking funny at parties but it is actually very useful: [15 uses for helium you never knew existed](https://zephyrsolutions.com/15-uses-for-helium-you-never-knew/) But here are good news! There is Helium on Jupiter! Actually it rains [Helium rain on Jupiter](https://physicstoday.scitation.org/do/10.1063/PT.5.024200/full/?ver=pdfcov) So, provided that the big spaceship manages to avoid falling in the gravity pit, you can go there and lower the bucket. P.S. notovny was 2 mins faster :) [Answer] Helium-3 is the most economical choice for mining from a gas giant. Hydrogen, ammonia, and methane are very easily produced, and nitrogen is in abundance and not going anywhere. But if your Earth-like planet has an Earth-like moon, then there's a good chance Helium-3 is there too. Should probably look there before sucking dry a gas giant. > > Now, it doesn't necessarily need to be a gas giant, but it must be at least a planet made of something the main planet is needing > > > In our own solar system, we've got proposals to profitably mine at least [11 different bodies](https://en.wikipedia.org/wiki/Asteroid_mining#Potential_targets), we're thinking of mining bodies made of magnesium silicate, aluminium, iron silicate, nickel, iron, cobalt, gold, platinum and... water. (Water is converted to fuel for the return trip - saving lifting it off the planet) You also can [mine (more like dismantle) Mercury](https://www.vice.com/en_us/article/yppepg/forget-wimpy-plans-and-nimbys-let-s-solve-the-energy-crisis-by-blowing-up-mercury) for free energy. [Answer] Helium is not only important for Fusion. Hightec often needs a cooling to 3 or less Kelvin. Thats mosttime done with Helium 4. (The normal one). The Large hadron colider in CERN institiute for examle, needs a couple of % of the worldwide traidable helium. Helium will become more and more expensive in our future. The most helium comes from the Oil and Gas industrie, but when this industire stopps, it will become very expensive. Gasgiants are made of hydrogen to almost 90% and almost 10% Hydrogen. All other stuff together has less than 2%. Nitrogen is a good idea too. You will need it for Terraforming, or Big Spacehabitats. Even if a Gasgiant has only 0,1% in his Atmosphere it would be a good source. ]
[Question] [ During the Cold War, the United States initiated [Project ORION](https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion)). This program was intended to build and launch super-heavy vehicles into space. They wanted to do this not with the use of chemical boosters, but rather by detonating small nuclear charges on the other side of a suspended plate which transfers momentum to the crewed vehicle. However due to bureaucratic conflict and fallout concerns, Project ORION never actually materialized. What change would have to take place during this process for Orion-type spacecraft to become a reality? By this I mean a world where eventually multiple such vehicles are launched and they see regular use in space operations. [Answer] Project Orion never came to fruition for multiple reasons, chiefly among them that there was no purpose for it. Remember, the space race, Moon landing, etc. didn't happen because people were totally pumped about space exploration or because scientists wanted to fulfill their curiosity, or even because people wanted to colonize other worlds; it all happened because the USA wanted to beat Russia. It was a matter of national pride, prestige, and asserting dominance over communism, not building cool spaceships. If there had been a good reason to develop Nuclear Pulse Propulsion into a viable vehicle, it would've happened (and could still happen). The technology and theory behind it is sound, and while difficult, the engineering hurdles are manageable with today's (and even Apollo-era) technology. But, it looks like you're asking for speculation, so let's speculate: Some historical reasons that might've caused project Orion to proceed * The USA is losing the cold war, the Soviets won the race to the moon, and the USA somehow concludes that they need to do something wild like colonize the Moon, Mars, or Jupiter * Project Orion somehow became the passion project of multiple high-level people including the president and enough legislators and military people to make it work Some modern/timeless reasons why someone might build a NPP spacecraft * Literal hostile aliens show up and the world needs spacecraft that can attempt to match alien capabilities. At this point, nuclear accidents are OK because it's deemed the planet is screwed if the aliens win anyways * There is enough money available for a serious, well-funded effort to explore other solar systems * Countries have space military with battleships and space marines. They need a powerful ship design and NPP is deemed the best option * Enough in-solar-system travel exists along with abundance of nuclear material to make it financially viable for companies to use NPP ships [Answer] A multitude of actual answers were developed during the period when ORION nuclear pulse drive were being actively investigated, but references are scattered all over the place, making it difficult to encapsulate this. Some of the best sources of information are through the [Atomic Rockets](http://www.projectrho.com/public_html/rocket/) website and the "[Unwanted Blog](http://up-ship.com/blog/)", who's author is a big fan. A man named [Anthony Zuppero](http://www.neofuel.com/index_neofuel.html) also came up with an.....interesting......use for ORION, which will also be discussed. While [4000 ton space battleships](http://fantastic-plastic.com/ProjectOrionBattleshipPage.htm) were seriously being proposed (having Minuteman ICBM's as their main battery, 5" naval gun turrets for close defence and so on, this was really more than a bridge too far. Much smaller ORIONs were pitched to NASA and the USAF, with the size constraint being the diameter of the drive plate had to fit a Saturn V booster for lift off. [![enter image description here](https://i.stack.imgur.com/bUUGr.jpg)](https://i.stack.imgur.com/bUUGr.jpg) Model of the 4000 ton space battleship proposal. Yes, this was actually a real proposal [![enter image description here](https://i.stack.imgur.com/4b3kf.jpg)](https://i.stack.imgur.com/4b3kf.jpg) USAF/NASA "10 metre" ORION. This was to be boosted by a Saturn V into orbit. From the Unwanted Blog By 1965, the ORION program was winding down, but General Atomics tried to sell the USAF on the program with a scaled down set of spacecraft, such as an emergency command and control center (blasted into orbit from a ground silo), an orbiting command post and a "bomber" on a long looping orbit which took it past the Moon and made it extremely difficult to intercept or eliminate America's nuclear deterrent. These were meant to be lofted by clusters of solid fuel boosters ranging from 7 120" solid fuel boosters (derived from the Titan III boosters) to 156" solid fuel boosters (4 for a lightweight ship and 7 for a heavy ship...) [![enter image description here](https://i.stack.imgur.com/mQ9Zm.jpg)](https://i.stack.imgur.com/mQ9Zm.jpg) Emergency command post lifting off [![enter image description here](https://i.stack.imgur.com/9NYoN.jpg)](https://i.stack.imgur.com/9NYoN.jpg) Model of proposed USAF ORION command post spacecraft [![enter image description here](https://i.stack.imgur.com/L7MW1.jpg)](https://i.stack.imgur.com/L7MW1.jpg) Bomber ORION on it's launch stack So ORION could be launched by various means. The launching of ORION using rockets actually invalidated much of the reason for having ORION in the first place: being able to launch heavyweight spacecraft from Earth. The idea of radioactive fallout and EMP from launch made launching ORION using nuclear pulse units a political non starter. However, if it is the end of the world, then perhaps that is no longer a consideration. Anthony Zuppero wrote an interesting memoire about his time working in the defence industry. as a thought experiment, he was asked to find a way to disable Soviet nuclear missiles in their launch fields "in two minutes" in order to prevent them from being launched. Zuppero went on to design perhaps the largest semi plausible weapon ever - a *5 gigaton* weapon launched from the United States on an ORION pulse drive...The thought of the largest nuclear weapon ever conceived riding skyward on a pillar of nuclear fire is, well... [![enter image description here](https://i.stack.imgur.com/9OJI7.png)](https://i.stack.imgur.com/9OJI7.png) Schematic of the Doomsday ORION by [William Black]. The design for the actual 5 Gigaton warhead is strictly conjectural.[11](https://www.deviantart.com/william-black/art/Doomsday-Orion-504250808) So in terms of making ORION a plausible vehicle, there is no doubt that it was, and using 1960 era technology as well. The idea of a high thrust, high ISP drive is still viable, but would have to be only for very extreme conditions, such as saving the world: <http://nextbigfuture.com/2009/02/unmanned-sprint-start-for-nuclear-orion.html> > > An unmanned Orion asteroid interceptor was designed. It would not need shock absorbers. Artillery arming, fusing, firing system for shells are regularly built to take 1000 Gs. > > > > > There was a three page paper: Nuclear explosive propelled Interceptor for deflecting objects on collision course with Earth. Johndale Solem, Los Alamos, proposed unmanned vehicle. No shock absorber or shielding. The pulse units were 25kg bombs of 2.5 kiloton yield. > > > > > Get to high velocities with only a few explosives and small shock absorbers or no shocks at all. Launch against a 100 meter chondritic asteroid coming at 25 km/sec. 1000 megatons if it hits. Launch when it is 15 million kilometres away and try to cause 10000km deflection. A minimal Orion weighing 3.3 tons with no warhead would do the job. 115 charges with a total of 288 kiloton yield. Launch to intercept in 5 hours. Ample time to launch a second if the first failed. > > > Outside of asteroid destroying interceptors, the ability to use ORION to launch heavy payloads from the ground is pretty much a dead letter. However, since ORION nuclear pulse drive is the only plausible high thrust, high ISP drive currently known (fusion drives need to actually demonstrate fusion before they can be considered), it will be highly desirable for deep space missions. In order to get the maximum performance from ORION, and use the smallest possible pulse units (people will be nervous about nuclear detonations in space, despite the fact space is already a high radiation environment, and particles from a nuclear explosion are moving at far beyond escape velocity, so will never return to Earth), the ORION formula will have to be inverted. [MEDUSA](https://www.centauri-dreams.org/2012/07/20/medusa-nuclear-pulse-propulsion-and-the-sail/) is a proposal to "invert" the ORION, with the plasma from the pulse projected against a gigantic "sail" ahead of the spacecraft. The thrust was transmitted to the spacecraft via a huge network of cables, making the entire structure in tension, and thus far lighter than the equivalent pusher plate structure. Since the sail is far larger than any conceivable pusher plate, much more of the energy can be captured. Combining this with a much lighter overall spacecraft system makes MEDUSA a wonderful method of transporting large payloads to the outer Solar System in a fraction of the time compared to other proposed methods. [![enter image description here](https://i.stack.imgur.com/J7P7r.png)](https://i.stack.imgur.com/J7P7r.png) Schematic of MEDUSA in operation [![enter image description here](https://i.stack.imgur.com/QyAjJ.jpg)](https://i.stack.imgur.com/QyAjJ.jpg) MEDUSA nearing Saturn So the best way to make ORION a feasible and workable system for actual use is to have it as a deep space propulsion system, capable of moving large payloads to the outer Solar System in reasonable amounts of time compared to ion, nuclear thermal or other known systems. This in turn requires some plausible and economically feasible reason to actually go to the outer Solar System. A few plausible reasons may exist: 1. Anti protons are captured by the magnetospheres of planets. The giant planets, with their huge magnetospheres, will capture usable amounts (micrograms, but antimatter is extremely potent), making rapid deep space travel economically viable. Capturing antimatter and sending it to Earth as an extremely compact energy storage and generation method is a plausible reason to do deep space missions. 2. Titan's atmosphere contains millions of tons of hydrocarbons. These are useful as chemical feedstocks for plastics, pharmaceuticals and fertilizers, among other things. A space economy will need these products, and having a "local" source that does not need to be lifted from a deep gravity well is a bonus. 3. Titan's atmosphere and extreme cold conditions also make it potentially the industrial powerhouse of the Solar System. The Carnot equation tells us efficiency is measured by the differential between the hot and cold side of a system. On Earth, the "cold" side is at atmospheric temperatures, but on Titan, the atmospheric temperature is hundreds of degrees below 0 C, meaning most processes and computing become far more efficient compared to the same things on Earth. This makes cheap, high speed transport vital. [![enter image description here](https://i.stack.imgur.com/NOqsD.png)](https://i.stack.imgur.com/NOqsD.png) Carnot Efficiency. When the difference between tH and tL are larger, the efficiency goes up So with sufficient reason to actually go to deep space destinations, ORION and its variants will be highly desirable due to their high thrust and high ISP, making fast and cheap transportation possible. [Answer] *The Earth is dying:* One possible scenario is that some vast catastrophe has or will soon devastate the future capacity of the Earth to sustain human life. In such a situation, getting MASSIVE amounts of stuff into space as quickly as possible, regardless of the consequences, would become the overarching concern. Say, for example, an asteroid was headed to Earth and scientists couldn't figure out how to stop it. Or a bunch of asteroids. Like ten dino-killers at once. Maybe they still try to divert it/them, but just in case, we want to built a gigantic space station. Also just in case, we build a fleet of Orion colony ships to get survivors off the Earth in case attempts to stop the asteroids fail. To jump-start this, the (US government? Russians? Chinese?) have been investing in the tech just in case the world was going to come to an end. They share the engineering, because they can't build them fast enough on their own, and fear that if they are the only survivors, vengeful rivals will kill (literally) the project. Even with Earth devastated, it would still be a huge, nearby source of material for our space colonists, and they would need a big spacecraft to haul tons of (dirt/water/metals) back into space. Once people accepted the Orion design, even if the asteroids were diverted (or especially if the Orions were central to diverting the asteroids) the ships would be accepted as established tech. [Answer] # Launch from international waters. The main obstacle to launching Orion Drive spacecraft is a political one, the result of nations deciding against the use of nuclear explosions for peaceful purposes lest they accidentally start a nuclear war, and writing treaties with other banning their use. As a result, if you wanted to launch Orion Drive nuclear pulse rockets, you would need to find a way to circumvent those treaties. Fortunately, there’s already a way to do so: international waters. The idea is fairly simple: you buy an oil rig, park it out in international waters, have it fly a flag of convenience of a nation that hasn’t signed those treaties, and convert it into a manufacturing facility for the nuclear pulse fuel units. You also build your Orion Drive nuclear pulse rockets as seaplanes (again, flying a flag of convenience), and have them take off conventionally from the ocean surface, and then start the nuclear pulses once airborne. The result would be a rocket that is somewhat less efficient than a more conventional, land-based rocket, since it would have to carry the mass of its wings and reinforced seaplane body into orbit with it, but it would be theoretically legal to build and operate. [Answer] A [2012 study](https://arc.aiaa.org/doi/abs/10.2514/2.5969) in the Journal of Propulsion and Power directly addresses your question: "[Project Orion's] feasibility was never dismissed on purely technical grounds. In fact, many of the scientists and engineers who came into contact with the program over its seven-year lifetime became convinced of its viability. The political and nontechnical issues that finally sealed the program's fate would certainly make the original Orion unacceptable by today's standards. However, new technologies and ideas developed since then could mitigate some of the major issues, and make nuclear pulse propulsion less unreasonable to consider for future human exploration." According to the authors, there's nothing technical keeping the ORION program from being restarted. If you want more details, here's [another proposal](https://aip.scitation.org/doi/abs/10.1063/1.2169260). And if you want a lot more detail, here's [an entire book](https://www.worldcat.org/title/nuclear-space-power-and-propulsion-systems/oclc/755949029) on different forms of nuclear propulsion. ]
[Question] [ Assuming magically animated skeletons capable of projecting the same muscle force as an average human (note: not someone who has trained a bunch or such, average) that are tireless and unceasing, what are the respective benefits and drawbacks of oars versus paddlewheel arrangements for the propulsion of oceangoing warships. The warships are assumed to be similar in construction and style to medieval Venetian galleys but other kinds of ships (sticking to medieval and maybe renaissance construction abilities) are acceptable. Weaponry for the ships can be assumed to be those of Middle Ages: rams, arrows, catapults, maybe greek fire or ballista. [Answer] As an alternative to either oars or paddle wheels, you could attach a diver's weight belt and a tow cable to each of your undead and then drop them overboard. Once they sink to the bottom, they could pull your galley along behind them as they walk in whatever direction you command. Since your skeletons no longer need to breath, their efforts need not be confined to the traction-less surface of the water. ...And think about how cool it would look... your galley just floats upstream with no visible means of locomotion. ...Also, during close combat, some of the skeletons can detach their weight belts and swim up to the surface to join the fight while the rest stay still, holding your galley perfectly still so that your archers have a more stable platform to aim from. [Answer] Besides allowing for much greater maneuverability in combat situations and navigating complex water ways, oars are surprisingly efficient! This [study by Cornell](http://ruina.tam.cornell.edu/research/topics/locomotion_and_robotics/oar_efficiency.pdf) puts the efficiency of oars at 84-85% The real reason for a paddle wheel is to convert rotational energy into motion so you can use your steam engine to turn a paddle wheel and push the boat upstream. With rowers, there is no need for this so having the fine control of paddles makes a lot more sense. Unlike a paddle wheel, an oar doesn't have a large amount of rotational inertia so the rower can change direction in an instant. Paddles can be raised or lowered in the water to change the amount of force applied to the water per stroke. Finally having a bunch of undead skeletons pushing on what amounts to a [paddle boat](https://external-content.duckduckgo.com/iu/?u=https%3A%2F%2Fi.pinimg.com%2F736x%2F83%2F55%2Fbe%2F8355be17d9381c6cf17e310742621378--pedal-boat-boat-names.jpg&f=1&nofb=1) would look quite silly compared to an army of the undead rowing a Trireme at ramming speed. [Answer] > > what are the respective benefits and drawbacks of oars versus > paddlewheel arrangements for the propulsion of oceangoing warships. > > > Paddle wheels definitely! If these creatures have anything like the mentality of zombies, the co-ordination needed to row as a team is going to be way beyond them. Also steering on a rowed boat depends largely on the rowers and less so on the tiller. These skeletons may be capable of learning to make crude rowing movements individually but the fine details are going to are going to be a nightmare. I suggest that they do have zombie mentality and they run relentlessly toward anything living that is nearby. The ship design would have two large hamster-wheels that are side-by-side but divided by a screen. These are each connected to a paddle wheel. A crew member could stand enticingly in front (or behind) each wheel to make them run in the desired direction. When turning, one of the crew members can hide and the other can move nearer to their hamster-wheel, causing the runners to speed up. To stop, both 'target' crew members disappear from view. To turn on the spot, one crew member stands in front of their tread-wheel and the other stands behind theirs. Sorry, it would have taken too long to edit in a full team of skeletons, but here's the idea. [![enter image description here](https://i.stack.imgur.com/W4zun.png)](https://i.stack.imgur.com/W4zun.png) [Answer] I am not an expert on the relative merits of oars and man powered paddlewheels. But it is a historic fact that man powered paddlewheel boats and ships were used in China for centuries, so it may be presumed that they had some advantages over oars for some purposes. > > China > > > > > The first mention of a paddle-wheel ship from China is in the History of the Southern Dynasties, compiled in the 7th century but describing the naval ships of the Liu Song Dynasty (420–479) used by admiral Wang Zhen'e in his campaign against the Qiang in 418 AD. The ancient Chinese mathematician and astronomer Zu Chongzhi (429–500) had a paddle-wheel ship built on the Xinting River (south of Nanjing) known as the "thousand league boat".[16] When campaigning against Hou Jing in 552, the Liang Dynasty (502–557) admiral Xu Shipu employed paddle-wheel boats called "water-wheel boats". At the siege of Liyang in 573, the admiral Huang Faqiu employed foot-treadle powered paddle-wheel boats. A successful paddle-wheel warship design was made in China by Prince Li Gao in 784 AD, during an imperial examination of the provinces by the Tang Dynasty (618–907) emperor.[17] The Chinese Song Dynasty (960–1279) issued the construction of many paddle-wheel ships for its standing navy, and according to the British biochemist, historian, and sinologist Joseph Needham: > > > > > "...between 1132 and 1183 (AD) a great number of treadmill-operated paddle-wheel craft, large and small, were built, including sternwheelers and ships with as many as 11 paddle-wheels a side,".[18] > > > > > The standard Chinese term "wheel ship" was used by the Song period, whereas a litany of colorful terms were used to describe it beforehand. In the 12th century, the Song government used paddle-wheel ships en masse to defeat opposing armies of pirates armed with their own paddle-wheel ships. At the Battle of Caishi in 1161, paddle-wheelers were also used with great success against the Jin Dynasty (1115–1234) navy.[19] The Chinese used the paddle-wheel ship even during the First Opium War (1839–1842) and for transport around the Pearl River during the early 20th century. > > > [https://en.wikipedia.org/wiki/Paddle\_steamer#China[1]](https://en.wikipedia.org/wiki/Paddle_steamer#China%5B1%5D) So a study of the history of man powered paddlewheel vessels in China to see what their uses were and how they compared to oar powered vessels would be useful. Of course your undead zombie crew would not get tired or need food and water like living crew members. And that should change the relative benefits of using oars or paddlewheels in ways I can't think of at the moment. [Answer] Please Note: I have no real experience in either paddleboats or rowboats, but I believe the relative benefits of undead in the sailing/shipping industry are obvious. Pros: 1. No Pay Required-Undead workers follow orders without question and without pay. 2. No Food or Water Required-For obvious reasons, undead do not require food or water, or even air for that matter. 3. Reliability-Zombies and skeletons operate (or can operate) at maximum performance 24/7. They need no breaks, they do not hesitate, and they can keep working as hard as they can for as long as required. If they can be "programmed" to follow simple commands (even lists of simple commands) then you essentially have robots that can spring into action and rectify the situation when emergencies arise. However, in most settings, the undead do not have the awareness and/or intelligence to recognize problems (or potential problems) in their environment and act accordingly, so this is probably a moot point. Cons: 1. Decomposition-Unless some magical and/or natural preservation techniques are maintaining your undead, they'll come apart when exposed to moisture, microbes, rats, or fungi. For the sake of #3 above, your zombies should really have some Enchantments of Preservation or high-grade mummification or resin coatings to keep them "fresh." 2. Lack of awareness/intelligence-As stated in #3 above, most undead lack all but the most rudimentary intelligence and awareness of their environment. This leads to problems akin to what I sometimes experience with computers; since they only understand one language, and they have no creativity, lots of orders will get misinterpreted or lost in translation. Basically, undead need either advanced "programming," higher intelligence, or a living being directing them in order to be helpful when situations change and initiative is required. However, in emergency situations, hesitation, panic, and even fainting are common, and that essentially takes out any advantage to a living director. In any emergency situation, you have at least a 10% chance of the director (captain?) being overcome and becoming absolutely useless, which results in failure and likely death as well. 3. Lack of precision-Undead are not known for fine motor control. Clumsy, robotic undead are a common fixture of any setting that include undead, and that would make rowing the obviously inferior choice. However, if undead retain the skills they had in life, or if they are capable of learning and executing tasks with precision, rowing is a more aesthetically pleasing (and perhaps more advantageous!) option. In summary, it depends on the undead in your setting. ]
[Question] [ In my story I have a group of androids that are able to grow in size from training and repair from damage because of the nanobots that are inside of them. Their skeleton will be made of a carbon nanotubes for the strength and weight advantage and their wiring can be nanowires for the improved conductivity. When thinking about how their internal nanobots will get materials and because I want them to seem as human as possible I thought they could eat normal food, with their nanobots stripping carbon atoms to use in creating more bots and repairing the body, which lead me to wondering if nanomaterials can be used for every part of their body? from internal mechanisms to soft skin? otherwise food might not be a good source for getting all necessary elements. The robots will secretly charge electricity through a port so whatever is digested will only be to provide materials to the repair bots. So my question is, in the future when nanomaterials are readily available, what other elements and materials would still be needed to make life-like androids? [Answer] Android meat. Like ourselves, your android eats to obtain materials for its body, and oxidizable fuels to power its metabolism. For the body, in addition to carbon, silicon and other materials readily available in the environment, your synthetic androids contain some materials that are very difficult to obtain - including rare earths like yttrium and certain bioinorganic molecules impossible to synthesize from scratch within the environmental constraints of the android's body. The android must purchase supplements to provide these needed materials. They can be expensive. Another way to get needed materials is from a different android that has them. This means consuming parts of the other android that contain the needed substances. The market value of various organs would depend on the substances they contain. Androids can share, and defunct androids are of course salvaged for this purpose. Androids and other biomechanical entities might be hunted and consumed for this reason. [Answer] Carbon nanotube have excellent tensile properties, but no astounding compression characteristics. They would be extraordinary tendons but very poor bones, at least in the way bones work in our skeleton. For a skeleton designed to operate in tension and not in compression it's a different story, but that's not what you have specified. That said, if you have an internal processing unit which can assemble atoms the way you want, as long as you intake them you are good to go. [This answer](https://worldbuilding.stackexchange.com/a/172120/30492) of mine explain the details. > > 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. > > > Replace "food" with the material you want, and you are done. ]
[Question] [ The world I am working on is a soft science fiction realm dressed up in the trappings of magic and the occult. A world where there are loosely defined scientific principles behind the rituals and relics of effective spell casting. Lycanthropy is believed to be nanite-actualized lunacy. Vampirism is explained as a side effect of an anemia cure gone wrong. I'm aiming at the soft spot, where the characters are living in world of infinite possibilities, but are still holding out hope that their faith in science will save them. Which leads me to question... I'm looking for a whimsical, semi-scientific "explanation" for demon summoning, and I would prefer that it involve time travel. Either fetching demons from the past, from an age before science destroyed the faith-base which fueled their existence, or from the future, from the chaos which is waiting for us once science inevitably falls apart. So is there a relationship between either the circle, the pentagram or the candles and any of the modern theories of time travel? [Answer] If you are so inclined to mix magic and science thus... I remember something about Einstein and his colleague Rosen - they thought at some moment that a wormhole may have each mouth in a different universe. [There is some elaboration on this in Wikipedia](https://en.wikipedia.org/wiki/Wormhole#Einstein%E2%80%93Rosen_bridges)). Moreover, their wormhole would only allow passage in one way. A summoning circle would then be one mouth of a wormhole. Assembling one will necessarily cause a mouth to appear at the target plane of existence, allowing whatever is there to cross to the plane of the summoner. Since we're dealing with wormholes, time travel is already heavily implied. The other mouth of the circle may be on either your past or future. Different circles may even draw from different times. [Answer] ## Look no further than the weirdness of Quantum Mechanics, and taking charge of infinite probabilities A few distinguishing aspects to [Quantum Field Theory](https://en.wikipedia.org/wiki/Quantum_field_theory) that may assist you: * So matter is really a series of waves, oscillating in various omnipresent fields that sometimes interact with each other. [Particles](https://en.wikipedia.org/wiki/Subatomic_particle) are point like waves that travel, it's actions governed by it's '[Wave Function](https://en.wikipedia.org/wiki/Wave_function)' * When a particle is emitted, it actually travels along all possible routes - only when it is Observed does it suddenly collapse the 'Wave Function' to be a particle. * Time is not as simple as we think it is. It is often 'reversible' and malleable. Some argue, in fact, [that time does not exist](https://en.wikipedia.org/wiki/Problem_of_time) in the Quantum world, only causal chains of events that are still reversible. This lends itself to your magic users - they could perhaps take the principles and do the following: 1. All possibilities could exist, and may have existed, even though the likelihood of its existence is miniscule. However, if your Magic User / Scientist could take advantage of the improbable, and make it probable, then it is possible a demon from the past could pop into existence. This actually happens all the time, particles can create themselves in the middle of nowhere, it is just the configuration of these particles that requires control over probabilities. 2. Time is not what we think it is. [Positrons are electrons](https://en.wikipedia.org/wiki/Positron) travelling backwards in time. The creation of a particle is sometimes dependant on time-reversal. [Look at Feynman Diagrams](https://en.wikipedia.org/wiki/Feynman_diagram) - it is possible to rotate interactions to be parallel to time-axis - meaning time is simply another dimension in space much like a coordinate system. Your Magic User / Scientist could discover the secret to manipulate matter in time, and therefore conjure material 'from the past'. 3. Observers in this universe are actually important. It is noted that the act of observation affects the universe. A [particle is indeterminate until observed](https://en.wikipedia.org/wiki/Uncertainty_principle) - so your Magic User could take advantage of this aspect, such that observations could lead to collapse of wave functions in a certain way. Shapes are important, as particles travel in all geometrical paths until observed. Your pentagrams, circles and other shapes could have significance by shaping particles probabilistically to travel in a certain geometry to attain qualities you want. For instance, light (a photon) can travel in a 'squiggly' line to a destination, however once [its wave function collapses](https://en.wikipedia.org/wiki/Wave_function_collapse) it is highly probable it travelled in a straight line, so this is what we (almost) always see. It could, however, have traveled in a pentagram instead, and this is a distinct possibility. By drawing or channeling light into a pentagram, perhaps certain possibilities are created more likely to summon demons (which again, is highly improbable). The world of Quantum Mechanics is weirder than you may think - in fact I regard it as much weirder than any fictional story I have read. Using it will reveal untold possibilities. [Answer] In the book [Nicolas Eymerich, inquisitore](https://www.goodreads.com/book/show/3245457-nicolas-eymerich-inquisitore) by Valerio Evangelisti, when the ancient pagan gods of Europe lost all of their followers due to Christianity, they migrated to exoplanets where they continue their existence. These planets can be (and are) visited by future humans with advanced technology, but pagan rituals can bring the gods back to Earth in a physical form, due to the existence of a fictional physical particle called 'psytron'. Psytrons travel much faster than light and they interact with human synapses which can excite them. This effectively enables a transfer of information or thought structures across space and time but also to 'crystallize' in physical form a thought, image or belief shared by a large number of people gathered in the same place. So basically you could exploit a similar fictional particle/entity that can transfer energy from the psychic to the physical plane to have either 1. a mechanism to fetch your demons from another planet/back in time/forward in time or 2. a mechanism to give physical existence to the demon based on the strength of the belief of its summoners [Answer] E8 So, strangely enough reality may mimic faith. Drawn in a way akin to the 8-fold way, or in an 8-pointed star and possibly best explored with (not kidding) 8-dimensional numbers called octonions, E8 is a 248 dimensional space that can be projected onto the 3-dimensions of space and one of time that we are used to. If written as a matrix, it is a mathematical expression with over 2 billion entries. E8 might be an effective way to look at M-theories, which describe a unification of all known forces at scales both tiny and enormous. [Answer] mumbo jumbo coming your way...my favorite mathematical and geometric theory go-to for ~~magic~~ soft science. [KNOT Theory](https://en.wikipedia.org/wiki/Knot_theory). A knot is a 'string' that is joined together so that it cannot be undone, the simplest knot being a ring/circle (or "unknot"). You can have more than one knot/unknot entangled together. Notice how some knot entanglements look similar to a pentagram to the uninitiated pitchfork wielding hordes. [![enter image description here](https://i.stack.imgur.com/m5LPA.png)](https://i.stack.imgur.com/m5LPA.png) Your ~~magic user~~ scientist is messing around with the entanglement of the ~~ether~~ atoms/quarks and other quantumly minuscule matter of the universes and whatnot. When they appear to be drawing a circle in whatever medium they are using they are actually rearranging the ether to follow a staged path of a 'knot' - a closed loop. SOMEHOW your characters have managed to find a way to rearrange matter at two different points in the universe both spatially and/or temporally. What with all that spooky action at a distance nonsense. When they manage to rearrange two unknots separated by either time or space together (image "a" in the figure below), they create a single closed loop that connects two points together allowing passage from one side to the other. Or maybe it's the process of separation that creates the connection between the two points. How your characters are physically doing this, I do knot know. It's a closely guarded secret. The ~~magic~~ science of the ~~demon portal~~ wormhole creation is a bit hit and miss... only the most adept arcane users have any success. Most magic circles are just that, circles drawn in the mud. [![enter image description here](https://i.stack.imgur.com/Rj4sJ.jpg)](https://i.stack.imgur.com/Rj4sJ.jpg) [Answer] Wormholes, black holes, ignoring the space/time between two points, it's all good that our science wizards can do that, but it's more than just the result, it's how to get there and how its done. The circle contains the method of travel for the hapless demon. Around the circle is your arcane symbols, and real geometries. Not the alien geometries -- those you summon. The symbols actually do something though -- they are an identifiable set of coordinates that identify either the entity that you aim to summon though space-time, or a location that this entity is at. If you are pulling demons from the past, this could explain why your runes are an older but recognizable script -- runes, hieroglyphics, etc. -- this is the alphabet that the demon summoning understands. For the summons that pull form the future, it's a script and we know it is, but it's not actually been created for language use, so it looks like magic letters. For reference, see the coordinates system of Stargate where the seven chevrons need to be set to a specific character to reach another gate. The geometric designs are a bit trickier as it is not just acting on this world. The central circle is obvious in that it defines the limits of the portal that is created. But the other geometries that the circle is inscribed hold a use in relating to how the portal maneuvers though space-time to achieve. Sometimes extra lines are added to obfuscate things, so how it bends might not be obvious at first. The candles are most likely accouterments because magic, no matter if it is arcane magic, or science magic, needs the dribbly candles and dark robes and things. But overall, the spell circle basically functions as a compact sort of spell program that is run on the universe to pull a living being (usually a demon, but occasionally an ordinary high school student) from a different point in space-time and deliver them to the present. Returning them to their own time is a bit trickier ... ]
[Question] [ Strange! this question does not seem to be on site with a search (only what to wear). I am concerned about the psychological aspect of food production and eating. Clearly tube food is out and I think production agriculture will be necessary besides molecular printers. Thoughts welcome. [Answer] They would probably be vegan by necessity Despite a lot of the negative press that has been out there over time about the vegan diet, the one thing that everyone seems to be able to agree on is that it is less resource intensive than an omnivorous diet largely because of the amount of land, water, food et al required to raise animals to eat rather than to grow crops. Taking that to the next logical step for a generation ship, you can't grow cows hydroponically. You can grow most plants that way though. Most of the research I have been doing on this topic of late (and it is a lot) is telling me that for physical health, a well planned and balanced vegan diet doesn't impede your health, and in many contexts actually improves it. Iron, protein and other ingredients for harnessing energy and building muscle are available in a plant based diet more readily than you might imagine, so I don't think that part of it will be an issue. The initial suggestions seem to be the same for mental health, but there is still a lot to do in that regard. Certainly a vegan diet is better than a meat based diet for fuelling your brain because it can't use much more than glucose as an energy source. But, there are still some strong arguments that without planning, an omnivorous diet is better for maintaining the brain, due to essential fatty acids, in particular Omega 3, DHAs, Taurine, Vitamins D, B12 - the list goes on. Some of this you can get from a well planned vegan diet, others you need supplements for, others we're still doing the research on them. Suffice to say though that if you're careful, you can not only survive on a vegan diet, you can thrive on it. What we don't know about this as a long term dietary proposition we're researching now to find out. This is good news for your generation ship as if you have a good hydroponics bay and the right seed stocks, you can support your crew more or less indefinitely this way and it will take FAR less resources and space to do so than it would if you also added meat animals to the closed environment of your ship. If for no other reason than they are competing with you for the oxygen in the atmosphere of your ship that the plants are creating, having animals with you as a herd is a really bad idea. I say 'more or less' because like so many things relating to biology, it's not as simple as growing the right food. There is another aspect to a generation ship that must be considered - ecological balance. The earth is a hideously complex ecology and a generation ship basically has to replicate the vast majority of that on a smaller scale. This is a practical impossibility to begin with because many of the life forms that you bring with you, including bacteria and the like, are going to evolve while you're on the ship meaning you really can't know how your ecology will evolve with them over time. You can do your best to stabilise your closed environment of course, but limiting the variety of animals is going to make things simpler. Arguably, you're still going to need bees for pollination, but the truth is that the fewer varieties of animals you need on the ship with you the less complex your closed ecology needs to be. Also, the less chance of diseases jumping species like SARS or Swine Flu, meaning that the environment is less likely to attack you. You're still not safe, but leaving as many animals either at home or in cold storage as you can lowers your overall risk. There is still a lot of work to be done in figuring out what plants you can grow, how many of them you need to thrive to support your crew and what supplements you need to bring along, but I'd be starting with a vegan diet just to reduce your ecological footprint in the first instance. [Answer] Asteroids. I mean, you could recycle waste for food (and NASA already does for water), but what if you are finicky, like me? Well asteroids have water, and carbon, and nitrogen. And that's basically what a plant is made of right there (ok well not entirely, but talking in generalities). Stop at the occasional asteroid, mine a few tons of the good stuff off there. Process it into the proper fertilizers and dirt. Add light with your nuclear powered grow bulbs. Plant your wheat and tomatoes and sunflower seeds for oil (cause you need that cheap oil for vegan cheese), next thing you know you have your space pizza. And space pizza means space pizza party. That's how we're doing it on my Disco Generation Ship. :) [Answer] A lot of this depends on your actual generation ship, most of all on your means of propulsion and on the price of getting material into orbit. The reason being that you need to build your ship in space (due to the rocket equation), and you want to build a really, really big ship. And the bigger you can build it, the more options you have for outfitting it. But let's look at things in detail: A generation ship by definition has to be huge. And it's purpose is to get a minimum viable population (plus some safety margin) to a distant destination. So, we are talking about a ship that can accomodate some 5000 people. And accomodate does not only mean to safely store them away and shield them from harm (radiation being only one of the problems), but to provide enough room for them to actually live. They also need to occupy themselves. And they will want to breathe constantly... All this means that they will be farming aboard their vessel, providing them with food, oxygen, and occupation, and quite some recycling. So, it is safe to assume that there will be fresh vegetables. Arriving at their destination they will want to be able to establish a colony, which means producing food. We already covered vegetables. But maybe they also want to bring animals. Animals are a bit of a problem. You can transport frozen sperm, even frozen fertilized eggs, but you need a living womb to grow an animal from them. You won't want to transport an entire minimum viable population of cows with you, plus one for pigs, chicken, and whatever else you want to bring. But you may want to bring enough animals to make sure you have at least one living female when you arrive, to re-breed as many animals of that kind from the frozen eggs once you arrive. That means that at any time, you will have one living female of any species, plus a few extra as a safety margin. And that means there will be steak!! Not on a daily basis, but from time to time there will be meat on the menu. Which is actually a good idea, because diversity helps with the morale as well as with providing energy and essentials. But there is a huge downside, obviously (there always is, when you talk about engineering). Those animals need space, and they need food. It is often said that for every calorie you get out of meat, you need ten calories to feed to the animals. I mentioned that the means for building your ship is important. Assuming you have the use of a space elevator. Then all that limits you (apart from engineering), is how much material and effort you are willing to invest in your ship. The larger you can build it, the more animals you can bring, and the more meat you can have on the table. If you don't have a space elevator, building your ship bigger than necessary to fulfill it's primary role will be prohibitively expensive. So, to sum it up: The population of your generation ship will mostly live on vegetables, with occasional bits of meat. And the amount of meat will depend on whether or not you have a space elevator at your starting planet. [Answer] They will eat genetically engineered yeast. [![yeast tank](https://i.stack.imgur.com/sx7uX.png)](https://i.stack.imgur.com/sx7uX.png) Yeast are good food. They are easy to grow. One could use electricity and water to reduce CO2 and H2O abiotically back to carbohydrate, and process any wastes back to carbohydrate as well, then feed them along with reduced nitrogen and minerals to the yeast. It is possible to genetically engineer yeast to make lots of different flavors, even with current technology. <https://courses.lumenlearning.com/odessa-readinganthology-1/chapter/audio-genetically-engineered-yeast-is-the-future-of-flavor-by-gastropod/> > > Until recently, the natural flavors that Hagen uses would, for the > most part, have been extracted from a plant; a handful of rarer > ingredients, more often used in perfumery, would have come from animal > sources. Today, advances in genetic engineering, combined with the > growing consumer demand for natural flavors, are creating an > intriguing new option for the world’s flavorists. In the past, the > mention of “edible yeast” in the FDA definition of natural flavors > typically referred to savory yeast extracts; now, designer yeasts are > beginning to pump out vanilla, saffron, and even grapefruit flavors. > > > It is easy to keep a lot of different engineered strains of yeast frozen, then grow them up for different food flavors. I propose that every different animal on earth will have corresponding yeasts, so your ship goers can go on a culinary virtual tour of the earth, eating their virtual way through the entire animal (including extinct animals) and vegetable / fungus kingdoms without risk of dying from food poisoning or kuru. Not all foods will be available at the same time and so shipgoers can mark the days until passenger pigeon and Yohimbe vine are on the menu. Yeast can also be engineered to make therapeutic and recreational drugs and the latter will be routinely used before embarking on aforementioned virtual eating tour of the world. [Answer] Prepare to be disgusted: # Waste, mostly. The way generation ships work is that they are standalone ecosystems entirely supporting themselves. This means there can be no waste of any kind. Excrement like faeces and urine would need to be reused after filtering, or as fertiliser. Even things like sweat would need to be caught and recycled. Basically everything a human consumes (and expels) would need to be reused at some point, as there are simply not enough resources to just throw anything out. How this looks in practise would most likely be the same as on earth, a combination of farming and livestock to recycle any waste. However it would need to be tailored with extreme precision, to make the recycling process as efficient as possible without the loss of any necessary nutrients. Mostly food would be boring and people would eat the same dishes and strict diets as they are designed to be the most efficient transfer of nutrients. The amount of ingredients available would be severely restricted. ]
[Question] [ Orgone is the conduit through which the power of the cosmos flows, focused through a sorcerer's will. Ritual practitioners must draw on this reserve of power in their souls to make a magic spell work. Spells require a constant infusion of Orgone through rituals that are performed inside a transmutation circle, which require a number of ingredients and can last anywhere from 30 minutes to several hours depending on the spell. There are five schools of magic that spells revolve around and are taught at universities: * Enchantment Spells – These are spells designed to capture cosmic power within a crafted item, so that its power can be called upon in times of need. * Protection Spells – These are spells designed to ward a user, object, or location against a variety of possible harms. * Transmogrifcation Spells – These are spells designed to fundamentally alter or control another living being or creature. * Transmutation Spells - Changing the makeup of different materials or combining them with others to make new forms of matter. * Scrying Spells – These are spells designed to allow a user to perceive in ways that go beyond his five senses. The more I think about it, the more I realize that many spells that fall into these categories cross boundaries. For example, an enchanted sword casts a barrier around an item (enchantment and protection) or a crystal ball made from transmuted elements that allows you to peer into the future (scrying and transmutation). With many of these effects infringing on each other's domain, the idea of schools of magic seems redundant. Getting a BA degree from. Harvard University or a PH.D from Hunter college seems pointless. I want a way to make separating forms of magic into categories necessary enough to be relevant, instead of an interdisciplinary form of education for mages. How do I design a magic based curriculum based on these parameters? [Answer] One of the ways to measure the health of a society is by collaboration, and that can be measured by specialization. For most of human history every individual was either a hunter or a farmer. With the rise of civilization we introduced what is arguably the most profound aspect of our species: our ability to collaborate and specialize. Not everyone has to be a farmer now. Now one person can spend all day making clothes and another working with the animals and another farming and another on the watch tower and another building homes and so on. This only works because of social trust - the more we trust and work with each other the more we can collaborate and specialize. This has been a measure of health in civilizations for the entire history of civilization. (quick aside: [Liars and Outliers by Bruce Schneier](https://rads.stackoverflow.com/amzn/click/com/B006ORT3KG) talks a lot about social trust. Schneier is a well known name in encryption and computing circles, but this book of his is a good read on the challenges we face in a digital age around social trust) When it comes to your magical universe, you want specialization! This is good. This means that you have an expert in Scrying who can do some Enchantment, but doesn't have to be an expert in both because he can find/hire/trust an Enchantment expert. And vice versa. Even within these five spells you'll have further refinements and more specialization. And that's good! It's a sign of a healthy society. It's akin to me being able to fix the basic plumbing in my house, but for complicated leaks and adjustments outside my comfort zone I can just hire a plumber. I've quite good at electrical work, and would be comfortable building out all the wiring in my unfinished basement without needing to hire an electrician, but for a large corporate office I would never try to touch that. So it is in your world. Everyone will need to know some type of basics, but then you build on that with specialization. We teach all children to read, write, do basic math, learn a little chemistry, etc, but then they graduate high school and go into specialized field - Psychology, Chemistry, Math, etc, and then even beyond that more specialization - Math:Group Theory, Math:Number Theory, Math:Set Theory, Math:Discrete, and so on. Have your world know some type of basics, and then educate and refine into specializations. [Answer] There is going to be some overlap. Consider a university: Everyone in the sciences takes Calculus from the math department. Biologists, agriculturalists, foresters, civil and ag engineers take courses in soils. Some spells are symbolic: You cast your spell by doing manipulations of symbols on parchment, much like doing a mathematical proof. Some spells are homomorphic -- they depend on the law of contagion. You can use the hair brush of the victim to find the body of the victim. At a much more difficult level you can use the hair on the brush to create a map between a voodoo doll and a person to manipulate that person. Some spells supplicative -- they depend on convincing/coercing Orgone dwelling entities (Angels, demons, pixies, dragons...) to do your will. Some spells are transformative -- they change the very shape of space and time. All scrying spells, portals, teleports And so on. Spells can use either the spellcasters own energy, or they draw on energy from elsewhere. Own energy spells are small in effect, but can still be complex. E.g. A tarnkappen spell to create an invisibility cloak for the wearer only requires bending light. Not much energy there. A thunderbolt spell, powered by your own self would be a static spark. Some spells have to be cast in pairs. Consider a catapult spell that has the effect of a 300 pound boulder hurled at a couple hundred miles per hour. The recoil would throw the spell caster into the next county. So the caster has to: \* Create the impulse \* Absorb the recoil \* Aim the impulse. This is why magic is hard. [Answer] Magic schools do not need to classify spellcasting. They can be a path. My martial arts teacher has described martial arts as a tall mountain we are all climbing. We are all taking different paths up the mountain, but we're all trying to ascend to the same peak at the top. As he put it, "I know one path up the mountain, and I will teach that path to you." Martial arts has two goals, if I may state them in an indisputable fashion. The first goal is to not get into a fight. In a real fight, everybody loses. The second goal is, if a fight is required, make sure you lose as little as possible. There are martial arts schools that will claim goals involving various ways of "winning," but I find the goal of "losing as little as possible" is a better phrasing. Win when times are peaceful. So there's two goals at the peak of the mountain for all of us. But there are so many myriad paths up that mountain that I would fail to count them all. Each one is a different path that is recommended by a school. Each one's path encourages a different toolkit of ways of solving a problem. Your magic system may specify five paths up your mountain. But, when you really dive into it, there's not five paths. There's many. Within those myriad paths, we classify them into five schools of magic, but every magic teacher really offers their own path up the mountain, based upon their life experiences. A university may choose to collect teachers with a predictable kind of path, and that would be worth something. To make this work, I'd recommend breaking apart the description of the spell from what the spell is. "The glass is half full" and "the glass is half empty" describe the same glass state, but they do so from different vantage points. An sword that can be used to cast a barrier (enchantment and protection) can be thought of as using an enchanted sword to create a barrier, or a way to create a barrier with an enchanted sword. The enchanters will think of it one way, the protection magic people will think of it the other. And thus they will use different terminology and each will have its own slightly different flavor. Bruce Lee was once asked the difference between a Chinese kung fu punch and a Japanese karate punch. He was quoted as replying that being hit with a karate punch is like being struck with a crowbar, while being hit with a kung fu punch is like being hit with a heavy metal ball at the end of a chain. You don't want to be on the receiving end of either. There may be a difference between getting hit by a punch of an individual whose knuckles are hardened by a protection mage, or one whose knuckles are hardened by a transmogrification mage. They'll have their own flavors. Don't get hit by either. They hurt. [Answer] # Mortal magic is like the visible spectrum of light: The power of the cosmos is like white light; but when it flows through Orgone into a context that mortals can manipulate, disperses and refracts as if through a prism. Each separate school is like a different wavelength of light: humans are able to pick out individual colors, but the schools actually blend together in a gradient. It's also possible that there are schools outside the "visible spectrum", which cannot be manipulated by mortals. ## The human soul is stained glass: Most people start off with "clear" souls, able to work with each wavelength of magic without any particular advantage or disadvantage. Over time, a practitioner's soul will become "stained" with the "color" of magic that they use the most. They'll develop an easier time channeling more magic of that school, but will develop greater difficulty channeling schools whose wavelengths are further away on the spectrum. This effect typically never becomes great enough to entirely prevent someone from accessing a given school, but it will make it much less efficient for them to do so. This encourages people to specialize in a few "adjacent" schools, and to collaborate with specialists in "non-adjacent" schools for spells that are particularly complex or demanding. ## Narrative Applications: This will allow you to divide some spells up as "pure" representations of a given school, but also justify the use of some spells as hybrids of two or more schools where appropriate. Depending on the number and variety of spells you intend to use, you can plan the spells out in advance, assign them whatever school[s] you deem appropriate, then use the results to plan out what order the schools should be situated in on the spectrum. [Answer] I'd argue the schools would form naturally if you could only be a master a very small area of what would seem to be a continuum of disciplines at the magical-phd level. The topics are split almost arbitrarily (or traditionally as is often the case) at a lower level so they fit nicely in a teachable curriculum. Using real world academia is a perfect model: At high school you get taught Chemistry. Later on you might do something more specific like Materials. Then in a phd you get to see how ill defined the edges of these discipline are (Material Engineering, Material Science, Material Chemistry, Polymers, Ceramics, Nano-materials etc.), but that doesn't mean the subjects are nebulous nor useless, they just have a focus on specific outcomes. They are necessary because the expertise and equipment costs and are so high that it's difficult to have any more than a cursory understanding of numerous topics. Ceramics and Material Engineering crossing over into Aerospace Engineering to design a new Jet Turbine seems like a perfect parallel for Combat Scrying and Material Protection crossing over with Enchantment for Swordologists. Plus I like the idea that the reader would have no idea just how deep the rabbit whole of magi-science goes. It would be fine for your "Bachelors" level mages to be still being taught like a Chemistry undergrad is still taught Chemistry, even though they realistically are doing a whole heap of Physics. [Answer] ## Jabberwocky University ### Est. 361 BC Student Guide for the Summer 2019 Term *Thank you for joining us at Jabberwocky U, home of the Devouring Oroboros'!* Please find enclosed an index to the colleges and degree programs for undergraduates at JWU for the Summer 2019 term. We want to remind students and parents that freshmen and returning sophmore students are required to live on campus, and should make arrangements for dormitory housing. Please also remember that dragons of any kind are forbidden on campus grounds, and any damages done to dragons found on university grounds is at the owners' personal expense. JWU will not be liable for any damages done to personal property by dragons, deities, or otherworldly beings that have not been summoned by faculty or staff. ### College of Economics The Smatty Perlmutter College of Economics teaches the application of divination to problems ranging from individual fortunes to macro divination. Students will learn how to recognize and apply economic principles to divination - where, when, and how to apply divination for best effect. They will learn the application of divination at a personal, business, city, national, and world level. Applied divination - methodologies for responding to divination results will be taught, as well as critical thinking, research, and problem solving skills. Students will create an instructor-led divination response, and apply it to a to a practical problem. ### College of Law The Kaiser Wilhelm II School of Law (formerly the Prodicus School of Ethics) produces the finest legal professionals of the world each year. Students learn basic divination, and divination as it is applied to disputes. Philosophy, and the derivation of law from the philosophy of divined truths is examined. Students will learn how to conduct appropriate research and prepare - as well as argue - interpretations of divination and the law. Students will learn contracts, bindings, dissolution, and will participate in mock trials. They will learn how to negotiate disputes, arrange settlements, or argue a dispute properly before a Court of Divination. ### College of Medicine At the Catherine de Medici and Emperor Justinian School of Necromancy and Medicine students will learn the living and unliving body. Alchemy, and it's application to heal injuries will be taught. Students will learn and name all of the physical parts and orgone chakras of the human body. Students will specialize within one of the sixteen different fields of Medicine, or become involved in the fast-growing field of Bio-Transmogrification. ### College of Veterinary Medicine Students of the Germanicus Conservatory of Veterinary Medicine will learn for the care of creatures of all kinds. Students are invited to concentrate in farm, field, woodland, domestic, abyssal, and extra-dimensional focuses, or remain broad as general practitioners. ### College of Logic, Frivolity, and Mathematics The Xenophon School of Logic is one of the original five schools at JWU. Students will learn the purest language of mathematics, it's logic roots, it's illogical roots. Students will learn to compose and defend theorems in mathematical terms that can be used by other mathematicians or applied scientists to prove or disprove theorems. ### School of Orgone Students at the Saint Willoughby Cloister of Orgone will pursue the pure science of this fundamental building block of the universe. Students will learn how to apply fancy, will, and spirit - both rigorously and frivolously - to solve problems, and explore ideas. ### School of Alchemy Students at JWU's School of Alchemy will learn the real and hypothetical properties of materials. Students will learn proper laboratory method, how to perform research, theoretical and industrial alchemy. ### School of Enchantment Schools at the JWU School of Enchantment learn the application of applied sciences such as orgone, alchemy, and mathematics to solve practical problems. Students may concentrate in almost one hundred concentrations of enchantment including mechanical, electrical, and alchemical focuses. ### College of Art The Diotima Colleg of Art teaches students beauty - both how to recognize it, and how to create it. Students will be invited to practice in several mediums: music, magic, light, and the written word to express fancy and actualize it into concrete form, as well as how to elevate the mundane to the extraordinary. ### College of Philosophy Why? Students of the Archelaus College of Philosopy are exposed to the greatest minds and most intractable questions of human existence. Students are taught to think for themselves and think from perspective, how to seek and recognize absolute truth, and how to recognize the many trapdoors and false starts in thinking. [Answer] All you need is different ways of doing the casting. One school draws runes; another chants words; another brews potions; another arranges objects in mathematical patterns; another dances. If the various effects are only achieved by a specific style of casting, you’ll have to get multiple degrees to cast compound effects or else work in teams with people from many schools. [Answer] # You can't separate them Well, not completely. Your mages will specialise in one field but need some knowledge in the others, to make full use of their magic. Take inspiration from the real world - a person who studied pure mathematics or even programming can't really only use these skills. Not in all instances. A mathematician who will do some sort of analysis will do it in some context - be that in a biology field where they use mathematics to decipher DNA, a sociology where they use statistics to gather data for individuals, in financial field they'd be using it on cash flows and/or risk. They they need other knowledge. Similarly, a software engineer can in theory build any sort of application. But in practice they won't if they don't have the business knowledge for it. A medical system will need awareness of medicine, a sociology system will need awareness of sociology, a financial system will need awareness of financing. You don't need an actual degree in the secondary discipline to be able to work with it, but you need coaching and at least understanding the fundamentals. So, similarly enchanters who only know enchanting will not be very effective, unless they are have enough skills to weave another spell and lay it into an item. They probably wouldn't need to study for a full bachelors degree (or equivalent) in Protection to be able to make a "brooch of shielding" but they'd need some knowledge in Protection and/or maybe a mage proficient in Protection. On the flip side, a Protection specialist wouldn't be able to just make an enchanted item. Perhaps with some knowledge of Enchanting they'd be able to cobble together something but it will not be as efficient and elegant - a brooch of shielding is out of the question, the Protection mage knows very well how to shield but doesn't have enough skills to weave that spell into a very small item. Perhaps something like a large shield...but that's not very convenient. Other problems due to lack of Enchanting knowledge might include the spell wearing out sooner or even abruptly ending without (seemingly) any reason. Problems that an Enchanting specialist may have had a two semester course on. A similar thing can happen with other disciplines outside of Enchanting. Protection + Scrying might be able to protect a caster from being scried on or maybe even guiding them towards things that will protect them (finding items, or even the futures where they don't get hurt). Or even slightly more mundanely (for magic...), protecting from overloading the senses when using scrying. But again, the full range of effects needs good skills in both fields - a Protection mage who doesn't know Scrying simply doesn't know how to protect against "bad future" or from sensory overload of senses they've never known of. A Scrying master without Protection skills cannot effectively isolate their senses from being tampered with or their fate from being scried. And so on, and so forth. So, specialisation gives you the tools you need for your field but you need other mages in order to make effective and useful spells. That's why you need a university that houses them. Different mages have to learn to work together. [Answer] You specialize through process and aptitude. I have a system based on 7 schools of magic which each have 7 sub-classes, and very quickly ran into the same issue of having overlap. I approached it by considering a similar question I have seen here before (but cannot remember it right now - If anyone has seen it before and can link it would be appreciated.) One of the answers was something to the effect of different ways to boil water, you could place it over a fire, pass electricity through a metal coil placed inside (kettle) , drop hot stones into the water, etc. All of these achieve the same effect, but take a different approach to achieve it. So your orgon users have to have a certain mental aptitude to use a specific school. Bob, who is a type 1 personality which is easy to use enchantment spells, but very hard to use Transmutation Spells. So in order to control his pet wolf, he enchants a stick with the property that every time he waves it, his wolf bites the person he is looking at. [Answer] ## I can think of two options ## 1. Each school of magic is based on a different fundamental spell or formula All of a schools spells are based on a different formula, and each schools formula is unique, if you try to use a spell with the wrong fundamental structure, bad things happen. learning a different school of magic is like learning magic all over again. Each school is like its own language (and may even have its own language), learning two schools is like learning Chinese and Spanish learning one does not really help you learn the other, it can even be a hindrance. Worse mixing them up can be very detrimental either from failure backlash or the random effects of botched magic. An example might be programming languages, some just are not really cross compatible. Many spells have different versions built in each discipline, and although roughly the same they differin in the details of how they operate. You have to reinvent the wheel so to speak for each school. for instance each school has their own water walking spell but they each have different costs, rituals, and side effects. Perhaps the transmutation version creates a spongy mattress like surface to walk on, while the protection version not only lets you walk on water but also covers the caster in hydrophobic coating like effect meaning even rain just sloughs off the peerson, or the enchantment version creating a rigid but slick ice like surface to walk on. You may learn about other schools superficially, like protection can do this and this but not this, you you are not going to learn their spells or spend much time on it. There might be geniuses that know two schools and can keep mixing them up but they are rare, as rare as meeting someone that can speak 4 languages fluently. "The graveyard is full of students who tried to use spells from other disciplines" ## Option 2, they do overlap just like real world schools of engineering but you still specialize. Biology, geology, physics, chemistry, sociology, ect. these are all different fields of science principles from one often can't be applied outside that field while at the same time their is a huge amount of overlap. You learn a bit about all of them but specialize in one field for your degree. I myself am a paleontologist, I have degrees in both biology and geology, my knowledge in those fields os far more extensive than my knowledge of physics or engineering. For your system a degree in Protection makes you an expert in protection you can cast other spells but the majority of your knowledge lies in protection spells, you have a larger variety of protection spells and can alter protection spells far more easily. You know the workings of protection sell intimately but that knowledge does not necessarily help you with any other schools spells, they are just different enough that principles you are not as familiar with apply. you can think of each as being the equivalent of having a degree in X-engineering, much like how in the real world you have seperate degrees in material science, electrical engineering, civil engineering, ect. you know something about other fields and can even do some simple low level applications in others but the majority of your expertise is in that one discipline. Bob is essentially Protection engineer, if you need a custom shield spell you talk to Bob if you need a water purification spell maybe you talk to someone else. but Bob is probably good enough to cast a water purification spell (off the self so to speak) but don't expect him to custom make one or diagnose a faulty water purification spell. Just like how you would not consult a electrical engineer to tell you why your dam collapsed or for how to create transparent aluminum, but you would want to talk to one about how to make a power grid. Why do we do this, because becoming an expert takes time, too much time to let someone become an expert in everything, so your major tells everyone what you are an expert of. ]
[Question] [ I am creating a world with roughly medieval levels of technology (It is actually in a Dungeons and Dragons campaign) and the world has just been almost destroyed. A city has been flattened to the foundations, and the survivors are trying to rebuild. They can find all the common resources they need (There is stone all over the place, tools are easy enough to come by etc) but have to rely entirely on the manpower of the townsfolk that survived (No magic for example). Anything uncommon I probably haven't thought of because I can't even put up flat-pack furniture never-mind build a wall, but they would likely have to acquire that so it would be an obstacle to progress, and useful for me to know They won't be looking to rebuild a metropolis, just a town / village big enough to be called a worthwhile\* settlement. Considerations are probably building a defensive wall, setting farmland, and enough shelter for however many people are in the town (The first place this will apply to has ~250 people). \*Worthwhile can be defined as: buildings that don't fall over in a storm, though they can be part wood and part stone; enough of them to provide shelter for the individuals; some kind of gathering hall (tavern maybe); plus clearing enough land to farm enough produce to sustain them. [Answer] Trevor and his source are right, but I don't think it tells the whole story. Certainly London lost a great deal of population because of the fire. Many people must have died, and many more would have been displaced, a large percentage of whom likely just moved away. Why would you rebuild a whole city that could house 100k people when you only need to house 20k? Further, it seems like the people already had somewhere else to live; they must have lived somewhere during 1667 after all. The point being there is not much call for new housing. Most medieval European civilian structures would have been [wattle and daub](https://en.wikipedia.org/wiki/Wattle_and_daub). The most time-consuming part of wattle and daub construction is simply gathering materials. A wattle and daub house requires a lot of mud or clay after all. Given 250 workers, they will be able to make relatively short work of this. I think that these people could, given adequate resources, finish housing themselves in a matter of a few weeks. Consider this [video](https://www.youtube.com/watch?v=nCKkHqlx9dE), in which someone builds a wattle and daub hut by himself in 30 days. I think it would be even faster, because his house looks like it could house 5 people or more. Assuming there's no diminishing returns in labor, that means a household could finish their house in just 6 days. I think it's likely there will be other delays; these people have other things they need to do besides build after all, but I also think it would be quicker than the 30 days in the video. So to me, anywhere between 6 and 30 days seems reasonable. [Answer] If townspeople have all resources (lumber, tools, beasts of burden) and there are no other urgent tasks to complete (like harvest), they can erect housing for everyone as well as wooden palisade within a month. This will certainly look like town, but probably not a "worthwhile" one. Stone construction used to take much longer in medieval times and relied on guest artisans and laborers. For a settlement of 250 people, stone wall appears like a formidable structure, and without outside help it should take decades to complete. [Answer] According to this PDF <https://www.museumoflondon.org.uk/application/files/6514/5511/5493/what-happened-great-fire-london.pdf> When London burned down, it took about 50 years to rebuild. > > It took nearly 50 years to rebuild the burnt area of London. St Paul’s Cathedral was not > completed until 1711. The city and the cathedral looked very different afterwards as this > view of London in the 1700s shows. > Throughout 1667 people cleared rubble and surveyed the burnt area. Much time was > spent planning new street layouts and drawing up new building regulations. By the end of > the year, only 150 new houses had been built. Public buildings, like churches, were paid > for with money from a new coal tax. > > > This seems accurate for any sophisticated structures. If you however don't mind a shanty town, then probably a few months to get started. There are some additional factors though. First, if the world, or even just a town has been reduced to nothing, there will be massive die-offs as people freeze and starve to death. With no sanitation, the survivors will die of disease. Eventually the few survivors will be able to rebuild and begin this process. Also, for working families, the family home could take a life time to build. [Answer] If you take a look at Gdansk then you'll see that it was burn to the ground by Teutons in 1308. According to wiki it look a couple of year before new buildings and roads were build upon what was left of Gdansk. In 1340 a considerable fortress was build and in 1358 Gdansk joined the hanseatic league. In 1361 people of Gdansk rose in revolt against Teutons. It seems that "rebuilding" a city could take a couple of years but regaining the power and prestige of the city will take circa 50 years. This does seem to support Trevors answer. Sources: <https://en.wikipedia.org/wiki/Gda%C5%84sk#Teutonic_Knights> <https://en.wikipedia.org/wiki/Teutonic_takeover_of_Danzig_(Gda%C5%84sk)> <https://en.wikipedia.org/wiki/History_of_Gda%C5%84sk#Monastic_State_of_the_Teutonic_Knights_(1308%E2%80%931454)> ]
[Question] [ In the future, defensive technology has advanced so much that weapons strong enough to kill an enemy soldier tend to cause unacceptable collateral damage. Sure, we can make a weapon that generates the force required to punch through a personal forcefield, but the blast tends to also destroy everything else within hundreds of meters making war a very messy and environmentally unfriendly business. Then one day, a well intentioned inventor figures out how to cause oscillations in an object's effective mass causing gravitational waves to radiate from the object. These waves have the same average pull as the original object, but the oscillations cause an alternating plus and minus gravitational effect. Any effects that gravitational waves have on space-time are assumed to still apply. The inventor quickly finds ways to manipulate these gravitational waves in pretty much all of the same ways that we can currently manipulate radio waves such as adjusting frequency, amplitude (measurable as plus or minus m/s²), directional transmission, etc. The government funding his research quickly realizes that gravity is not affected by any known defensive technologies; so, they decide to take over the inventor's research and try to find a way to use gravitational waves to kill a person through their armor, shields, etc. without causing lots of collateral damage. Given the nature of the human body, what is the ideal amplitude, frequency, and methodology required to kill a person with gravitational waves while minimizing collateral damage. As per comments: While this would require a ridiculous, down-right stupid amount of power as per our current understanding of physics, assume his method relies on a handwavium mechanic that can be achieved with a power source that would not itself cause collateral damage. [Answer] Balance A small, constant wave could be used to knock someone off balance. If they're crossing a bridge or atop a ladder or the roof of their house at the time, that could kill them. Cardiac Arrhythmia Pass a wave through a human's heart and see what happens! Cardiac arrhythmia is when the heart starts beating in the wrong way, and that leads to death, too. Unconsciousness, concussion, or coma Pass that wave through the brain and watch it shut down! give it a good yank to the left and see if they can ever draw a straight line again! Why are these suggestions useful? Weaponizing isn't always about killing. A friend of mine in Finland, where they have mandatory military service, once explained that killing people wasn't at all what he was trained to do. If you kill someone, you've removed but a single person from the battlefield. But if you wound someone, it takes 1-3 more people to get that person off the field. Now you've removed up to 4 people from the battlefield. And that assumes that you're on a battlefield. Just because the gun shoots bean bags, rubber bullets, blasts of water or air, doesn't mean it's any less of a weapon. Gravity waves would be great for crowd control. Yup! Make them all unbalanced (think about the "sick stick" from the movie Minority Report. That's what you'd have, people hurling just like they would on roller coasters.) You also have the stunning applications, like tasers. Small gravity waves knocking people unconscious or senseless have great applications in the field of kidnapping! And you wouldn't need the gravity of a planet to pull some (or, I suspect, most) of this stuff off. What you need is precision. You need to hit just the heart, or just the right part of the brain or inner ear. Would it be practical? Heck if I know. That's Nosajimiki's problem. But there are ways to weaponize the use of gravity waves, IMO. As for ideal amplitude, frequency, etc. I'm voting for the 10-30 Hertz range as that's where audio tends to move people in a more physical, less emotional way. I haven't the foggiest what the amplitude would be, but if the amplitude is measured in "standard gravity" (i.e., if Earth's g=9.807 m/s2 then let's call that "unity" and name the unit of measure the "Nosajimiki.") So, you'd likely start really screwing up the human body with 1.5-5 Nosajimikis. The one problem you do have is that gravity goes through things in a way light and slugs don't. The collateral damage might be ugly. This could, perhaps, be mitigated by using a stereoscopic transmitter that had to be focused such that the maximum amplitude hit just where you wanted it, but every where else the two beams were smaller. Just a thought. [Answer] If you wish to cause a human to be thrown in any direction with this technology, you will need to summon up the mass of an Earth. That is not sanitary, as the collateral damage will be the planet as a whole. Rather, you could cause someone to vibrate very fast by changing their mass. Increase and decrease in short intervals and see they become jelly. However, that still takes a lot of energy. To increase a person's mass by even 1 gram takes close to 9 x 1015 joules. If you just pointed a laser in their direction, that laser could probably pierce through meters of concrete. For comparison, the energy input the Earth receives from the Sun on its day side is about 1.73 x 1014 watts. You read it right - you would need to collect all the sunlight that hits the Earth for almost a a minute and a half in order to have enough energy to make someone marginally lighter or heavier. The amount of heat you're going to generate from the power source alone can probably destroy a few ecossystems, so you should probably collect power and fire your weapon from space. Much cheaper and cleaner would be to [just vaporize people, which takes in the vicinity of 3 x 109 joules per adult](https://worldbuilding.stackexchange.com/a/108341/21222). [Answer] Massive amounts of unobtanium, handwavium, and pure old magic. Gravity is a force with a very small local effect, but very large effective range. That is, if you grab your typical magnet and lift a paperclip with it, you are using the force of magnetism to counteract the force of gravity of the entire world. That is, a 25 gram piece of magnetized metal is lifting a 1 gram paperclip, despite 6 septillion kilograms of mass (gravity) working to pull it the other way. If you have a weapon that can harm a human using gravity waves, it also does the same amount of damage to the entire planet. There is no known mechanism is science or fiction that would contain a gravity wave, so your only option is to just make something up. Reverse the triangularity of the flux proton sequencer. [Answer] Think outside the metric. Directly hitting the opposition with gravity waves might be less useful than other easy possibilities. What you want to do is distort things in a way that causes problems. Brute force example: The novel Protector by Larry Niven had the idea of using gravity lenses for an interesting telescope. His telescope had an enormous input aperture so that he could observe very faint objects. Imagine then, a gravitational lens system about 100 km across that focuses the light from the sun down into a nice narrow beam only 1 km across. It's then 10,000 times as intense as sunlight. Instead of 1 kW per square meter, it's 10 MW per sq meter. Probably that is a city buster. Subtle-then-brute-force example: Fairly small pushes could re-direct a comet. So a comet that is out in the Oort cloud, nosing along in an orbit that nobody will notice, gets nudged into an orbit that will intersect the target. Maybe nobody notices you doing the pushing, especially if you are careful to keep the unusual stuff pointed away from the opposition. After orbital mechanics takes it's toll, a 20 km comet hits your target. Yes, it has a few year delay for the time required for the comet to get from the Oort cloud to the planet you are attacking. How patient are you? Subtle example: If the opposition is doing space travel, little pushes can make their space vehicles drift off course. Presumably they have a finite ability to correct. Combined with the gravity telescope of the first part, maybe incoming potential attackers can all get flung to oblivion before they can fight back. Subtle example: Bending light might be used to produce mirages, hidden objects, etc. When the opposition looks at your base maybe they see a duplicate of some other part of the sky. Maybe when that comet is heading toward them they see also a duplicate of some other bit of empty space. So they don't get warning and so can't do anything about it. [Answer] The key way to cause damage with gravity will be tidal forces. These are strongest in regions where the gravity gradient is steepest. This doesn't necessarily mean where gravity is strongest; larger black holes actually cause weaker tides than smaller black holes. So consider your gravitational waves like sound waves. It is possible to mix multiple frequencies of sound waves so they cancel out everywhere except for one small point where they add up. So they're silent in most places, but in that one spot they're extremely loud. If your equipment is very precise, this point can be arbitrarily small, meaning the sound starts and stops very abruptly. I suggest you do something similar with gravitational waves. Generate multiple frequencies synced up just right so they cancel out in most places, but add up abruptly inside your opponent's ship. One half will be pulled in one direction, the other half in the opposite direction. ]
[Question] [ Answers to [this question](https://worldbuilding.stackexchange.com/questions/39736/what-would-humans-wings-need-to-be-like-to-fly) note that human (and by extension mammal) wings would use naked skin instead of feathers, as we see on bats. However, with feathers, birds can have wings with shaped more like those of an aircraft (often with [bell-shaped spanload](https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20110023801.pdf), it seems), which is more efficient than a flat surface for generating lift, without adding as much weight as would flesh. In comparison, bat wings are very flat. Would having inflatable air bladders under the skin, in order to give a similar shape, be beneficial for generating lift? Or would the gains be too marginal to be worth it for a flying mammal? Some answers to [this question](https://worldbuilding.stackexchange.com/questions/95835/could-you-make-bat-wings-shaped-like-the-different-kinds-of-bird-wings) note that bat wings are more agile, at the cost of being less efficient for generating lift. The idea here would be to compromise differently and have better gliding wings. [Answer] It would have benefits to lift, but they'd be very susceptible to damage. Adding air-filled bladders to a wing to make it more aerodynamic would be a lightweight solution to adding lift compared to adding supporting structures so there would be benefit to it. Issue 1: damage However, skin wings are already more susceptible to damage than feathered ones. The loss of even a number of individual feathers does not necessarily ground a bird, but damage to a bat's wing is easily exacerbated into a full tear through use. As a response to this, bat wings have evolved to be some of the fastest healing mammalian tissue structures. If you are relying on the aerodynamic shape of an air-filled bladder on a wing to generate enough lift to fly, then damage to that structure is pretty risky. If a bladder becomes even slightly punctured it will deflate and ruin your aerodynamics. You may still be able to fly using a deflated wing, but evolution tends towards efficiency so it is more likely that any small injury would result in the animal being grounded until it heals and inflates again. This doesn't necessarily mean that the trade-off isn't worth it, but the benefits are looking pretty thin. Issue 2: alternative solutions The usual solution to gaining more lift is to evolve bigger wings. Either longer or broader, depending on your flight strategy. There are drawbacks to this (higher wing-loadings, lower manoeuvrability, and more weight), but it is also quite an easy thing to evolve compared to novel structures within a wing. Smaller wings are better for manoeuvrability and lighter weight. They tend to be selected for in environments where animals have to fly around hazards like branches or predators. The issue we have with bladder-wings is that what we're after is high-lift small wings. Unfortunately, as these are typically a response to hazardous environments, a solution that is very susceptible to damage is not a great solution. Add together inefficient solution and difficult to evolve and it's not hard to see why it hasn't occurred in nature thus far. So, how can we make this plausible? Perhaps, what we want is a situation where simply increasing wingspan isn't enough. We also want a situation where lift is at a premium over manoeuvrability, and risk of damage is low. Maybe your bladder-wing bats are pelagic sea gliders like albatrosses. If you're big enough, there's not a great deal out above the open ocean that will damage your wings, and lift is most certainly at a premium if you want to fly vast distances. There have been pterasaurs with very large wingspans so it is possible to have very big skin wings. So, they'd probably just evolve really big wings like pterasaurs and albatrosses. Drat. Hang on...we might be able to get this to work... There are some [key trade-offs](https://en.wikipedia.org/wiki/Tradeoffs_for_locomotion_in_air_and_water#Flying_birds) for animals that both fly and swim. The one we're interested in is the relative wing-loadings of animals that use their wings to swim. As water is so much more dense than air, you need a lot stouter wings to swim well in it. There's a trade-off between ability to swim underwater and fly in the air. Puffins have tiny wings and very inefficient flight in order to be able to swim very well underwater. Flightless penguins are the logical extreme of this. If an albatross flapped its massive wings underwater it would break its bones. As such it's unable to dive, and is relegated to a feeding strategy where it attracts squid to the surface at night. It works (evidently), but there's a lot of resources albatrosses can't exploit. This sets up the right set of pressures to favour high-lift short wings. If your bladder-bats are able to deflate their bladders to decrease their buoyancy, they might be able to travel vast distances at sea efficiently and dive well enough to hunt beneath the surface of the water. They also avoid the trade-off of water-repellent feathers trapping air and increasing buoyancy so might be better divers than birds. They might actually be able to compete well enough with albatrosses (and other diving pelagic birds like shearwaters) to plausibly survive in the wild! tl;dr The only plausible set of environmental pressures I can see for bladder-winged bats comes from long-distance flying diving pelagic sea-birds. [Answer] At the scale of a bat (normally not much bigger than a house mouse, maximum about the weight of a large rat) the cross section of the airfoil makes much less difference that it would with something that weighs, for instance, what a large hawk or albatross does. In fact, the bat's thin wing has a much thicker bone "spar" near the leading edge, and a deeply cambered surface behind; this is actually a very efficient shape for a small (low Reynolds number), low-loading surface. To compare, look at the difference between the wings of small hand launched gliders (typical span 30-45 cm, weight comparable to a small bat) and those of larger model sailplanes (spans 1.5 to 3 m, weight 1-5 kg). The hand launch gliders have very thin wings, and in fact often little camber; this latter is because they need to fly at very high speed when launched, but the designs that have used built-up wings to add thickness have not generally done enough better in competition to take over from the thin solid sheet wing construction. It's also common for indoor hand launch gliders to have flexible cambered surfaces -- the camber "blows flat" during the high speed launch, then flexes back like a flap to increase lift and change stability during the glide. In final configuration, the result is much like the inner panel of a bat's wing (inboard of the "pinkie finger" bone). Therefore, in considerable of the relative fragility of an air bladder (as mentioned in another answer) and the questionable aerodynamic advantage of a thicker wing over a thin, cambered one in this flight regime, it seems unlikely that such a feature would provide enough advantage to evolve naturally. ]
[Question] [ Looking at the case of [Mike](https://en.wikipedia.org/wiki/Mike_the_Headless_Chicken), I realized decentralizing the brain might not be infeasible. The idea is if Horus, the brown falcon, doesn't have enough room in his skull, then why not move various functions to relatively well-protected areas of the body, and also expand the brainstem downwards while we're at it. Though I'm still unsure. Where should I place the central motor generators? Where'd they be safe? Where'd there be enough room for them? [Answer] A good example will be [Octopus](https://en.wikipedia.org/wiki/Octopus). > > The octopus (along with cuttlefish) has the highest brain-to-body mass ratios of all invertebrates; it is also greater than that of many vertebrates. It has a highly complex nervous system, only part of which is localised in its brain, which is contained in a cartilaginous capsule. Two-thirds of an octopus's neurons are found in the nerve cords of its arms, which show a variety of complex reflex actions that persist even when they have no input from the brain. Unlike vertebrates, the complex motor skills of octopuses are not organised in their brain via an internal somatotopic map of its body, instead using a nonsomatotopic system unique to large-brained invertebrates. > > > [Answer] A less centralized nervous system is an anatomical feature seen in non-uplifted animals in real Earth. For example, insects have brains, but they also have neural ganglia distributed through their bodies. These ganglia are responsible for functions which in us are all processed in the head, such as locomotion and gut movements. ![Insect nervous system](https://i.stack.imgur.com/oooSM.jpg) And then there is the stegosaurus, as well as some other dinos such as the larger sauropods. They had such a small skull size to body size ratio that for some time scientists thought they had "extra brains" in other parts of the body. In the case of the stegosaurus, they thought a secondary brain might exist inside the hip. Going a bit further - in our own case, our central nervous system is not limited to what is in our skull. The spine does some processing too, though it's mostly related to reflexes, involuntary organ movements and signal routing. But what matters is that it does have its own processing. It's not a far stretch in biology to have it augmented. --- For a sci-fi reference: in the Star Wars universe, there is a species called the [cereans](https://starwars.fandom.com/wiki/Cerean). These guys have two brains in their skulls, which I think could make for extra brain power compared to humans. The most famous one is Ki Adi Mundi, a Jedi knight who was a member of the Jedi Council in episode one. ![Master conehead](https://i.stack.imgur.com/RTRdA.png) [Answer] Your nervous system is more distributed than originally believed, but the degree to which this is true is still a bit uncertain despite it being a major point of study since the early 1800s. What is known is that the human spine contains the majority of your body's reflexive functions and motor memory effectively making your spinal cord part of a sort of distributed nervous system like you are asking about which could in theory be pushed to a greater extreme by moving more functionality into your spine. But this may not actually be as good as you would think. Your spine is a logical nexus for performing practiced or reflexive actions because it is so much faster than having to think through the whole process. That said, biology often prefers the "brain" model because the closer you put neural structures, the faster they can communicate. So, by clumping together all the stuff responsible for registering senses, interpreting them, and making decisions based on them, you can think much faster, and do a much better job of letting the inputs of your different senses work together to create a unified understanding of your environment. With all of these factors in mind with regards to distributing a bird's neurology, the answer really comes down to how important centralization is to the way a bird operates. In cases like octopus biology as Chenxi GE points out, we see organisms where coordinating the activities of each appendage with each other is far less important than being able to control all the countless ways an individual part of the body can move and react to its environment. Birds however need to be able to walk, run, and/or fly which each require rapid top-down co-ordination. If a bird moves one wing and the the other wing, or tail, or feet, etc. does not react to compensate, then the bird will tumble. If a bird sees a tree branch, every part of his body needs to precisely work together to land on it. In short, if you move stuff out into the appendages, you slow down reaction times which will probably make basic mobility much more difficult, and if you put too much into the spine, it could still coordinate certain things, but it will still likely get itself killed when it encounters a new situation where the body reacts without evaluating its context. Also, if your concern is brain size, you may be overthinking it. Brain size is not nearly as good of an intelligence indicator as you might think. Something we often see in dog breeding is that you can make an animal's brain several times smaller without making it any dumber as long as all the same neural structures are there. It is unknown how far this limit can be pushed, but when you consider that lab mice have most of the same brain structures as a human, I'd assume the limit is much smaller than nature normally cares to go for. [Answer] I think you may be better off leaving the brain in the head. ### Pros * Less areas to protect - Horus knows that he has to protect his head and his heart, mainly. If you moved parts of his brain to other locations, he'd have to protect all of them. During a fight, it may prove quite hard to protect your head(to not lose your vision) and all the places of your body where the brain is spread over at the same time. * Have it next to the input devices - if you notice a sword swing by your enemy, you have to react immediately in order to block it. If you have your senses far away from your brain, it may take you too long to react. * Have it all at a single place, in order to think fast. The closer the neurons and the shorter the paths that, the faster your thinking. Having your brain spread all over your body may not be a good idea concerning that. * Head and skull as they have evolved during the ages offer a quite good protection and it I wouldn't question evolution... ### Cons * A single strike can end your entire existence, in that case you may be better off if left disabled due to losing several brain case --- *An alternative could be having multiple brains*** ]
[Question] [ What would make a good propulsion source for small engines and manouvering thrusters for spacecraft vehicles on Europa (moon of Jupiter), both for near-surface operations (vacuum) and in caves beneath the ice (low or medium pressure)? I am only interested in spacescraft thruster propulsion systems, not wheels or tanks tracks etc. My version of europa has an extensive cave system within the ice, which will be navigated by spacecraft using thrusters. I am ignoring gas pressure and propellors, and assuming the pressure is too low to bother with aerodynamics. Say my colonists have ample amounts of electricity from fusion power. They want to use local materials if possible. Refueling drops from other locations in the jovian system are acceptable as long as they are plausible and make economic sense... [Answer] This is a big rewrite of my answer following big changes to the OP. The original stuff is still in the edit history, if you cared. --- The critical question is... how light and compact are your fusion reactors? If you can fit one on your vehicle and they don't weigh too much and they make use of [direct energy conversion](https://en.wikipedia.org/wiki/Direct_energy_conversion) (rather than merely being [thermal power plants](https://en.wikipedia.org/wiki/Thermal_power_station)) then you can use something like Bussard's ARC/QED design (all regeneratively cooled quiet electric discharge). I did have an online source for the paper describing this, but the link is now dead so I can't shared it with you. It uses electron beams to heat reaction mass (which could easily be water), gets 1000 seconds $I\_{sp}$ or better, could probably do SSTO on earth and so would be fine for all your needs on Europa with power to spare. If you don't have compact portable fusion, then you have some problems. Using the most common local resource, you have 3 basic options. 1. [Steam rocket](https://en.wikipedia.org/wiki/Steam_rocket) 2. [High-test Hydrogen Peroxide](https://en.wikipedia.org/wiki/High-test_peroxide) monopropellant rocket 3. [Liquid hydrogen/Liquid Oxygen rocket](https://en.wikipedia.org/wiki/Liquid-propellant_rocket#Cryogenic) (LH/LOX) If you have access to carbon or hydrocarbons, you could synthesise a rocket fuel and use peroxide of liquid oxygen as the oxidiser to make a more conventional biopropellant rocket. If you had access to nitrogen, you could make [hydrazine](https://en.wikipedia.org/wiki/Hydrazine) which can also be used as a monopropellant like peroxide only more efficient, toxic and hazardous to store. (1) steam rockets have the problem that you either need to generate the steam on board your vehicle (which will require a big battery or generator) or generate it ahead of time and keep it hot. Pregenerating it won't help much for longer journeys and storing high-pressure steam requires very strong, heavy tanks, so I think pregenerated steam rockets are out. You can generate steam on board with battery power, but you might have problems competing with peroxide rockets. The specific energy of peroxide is something like 2.7 MJ/kg, which is three times that of the best rechargeable lithium ion batteries today. Your future battery storage tech might be an order of magnitude better, eg. [lithium air](https://en.wikipedia.org/wiki/Lithium%E2%80%93air_battery) in which case this is achievable, but you'll need to find a good supply of lithium and I have no idea how abundant it might be on Europa or in the Jovian system. If your powerplant and its fuel is light enough, you could generate the steam on-demand, and refuel with the aid of a pickaxe. I've not looked at how light and efficient such a power plant would need to be though, because the maths is more fiddly than I'm prepared to fight with right now. A lightweight thermal fusion plant would fit the bill, I'm sure. (3) LH/LOX is the best for power and efficiency and so on, but storing LH is a nighmare. It is super low density (so you'll need massive fuel tanks), [damages various structural metals](https://en.wikipedia.org/wiki/Hydrogen_embrittlement) and has such a low boiling point that even on the coldest parts of Europa you'll still need insulation and refridgeration to keep it liquid. LOX can actually freeze in the colder parts of Europa, but not as readily as peroxide so keeping it liquid isn't so hard. Lots has been written elsewhere about LH/LOX rockets, so I won't say more. This brings us to: (2) hydrogen peroxide monopropellant rockets have high density fuel (up to 1.4 times more dense than water depending on concentration), are easy to ignite (just spray the fuel over a suitable catalyst of which there are many... silver wires are one), burn cleanly and are more or less non-toxic in the event of leakage (or at the very least, are easy to denature). Peroxide has roughly the same melting point as water, so you'll have to work to keep it warm to use it in a rocket. With a practical $I\_{sp}$ of 140 seconds it is clearly not a super efficient fuel, but you can easily make decent high-thrust rockets from it capable of flight on Earth, let alone Europa with its 1/8th gravity. [![Rocket belt](https://i.stack.imgur.com/5qOcw.jpg)](https://i.stack.imgur.com/5qOcw.jpg) The [RB2000 rocket belt](https://en.wikipedia.org/wiki/Bell_Rocket_Belt#RB2000_Rocket_Belt), a modernisation of a 50s design by Bell, can actually fly an adult human around in Earth's gravity. The design should scale up OK... Bell made a 2-man stand-in vehicle design based upon their earlier work, so I'm happy that it is a plausible basis for larger, more complex things. You'll get a $\Delta\_v$ of about 370m/s out of it, which isn't a whole lot, and about 4 minutes thrust time on Europa, and that's with 25% of the takeoff mass being fuel. On earth it would struggle to lift much more fuel, but there's some scope on Europa to carry larger tanks for longer trips. As you can't use lift or otherwise float on an airless world without the aid of your rockets, you'd be well advised to use a hopping strategy, with special sprung undercarriages to recover kinetic energy. Oh, and sickbags. Lots of sickbags. Finally, non-rocket advantages of carrying around peroxide: it is like an instant life-support package. It provides heat, oxygen and water, and once you've defrosted a tiny bit (eg. with body heat) you can use the heat its decomposition generates to defrost a lot more. [Answer] Under the ice: Under the ice on Europa, there is... more ice. The upper layer of the planet is actually a solid ice layer, similar to the upper mantle of the Earth. While solid, there is a lot of convection (on Earth this creates tectonic activity), so if you drilled a tunnel down there, it would collapse pretty quickly due to the shifting ice. Also, as you drilled down there would be lots of pressure from the gas formed by sublimating ice that you've newly exposed to the vacuum of space. So vehicles designed to go down there would have their own drilling equipment and be able to fix themselves to the ice, maybe using giant spikes or equivalent. If and when they get down to the water level, they would probably stay as close as possible to the surface to avoid getting caught in underwater currents caused by the tides (when you orbit a gas giant, your tidal forces are very, very strong), so I doubt you'd even have a submarine-like design, just a tank that claws its way through the slushy ice-soup that saturates the top levels of the oceans. On the surface: Easy peasy. Europa's gravity is about 13% of Earth's, so you could propel yourself with jets of water vapor expelled from RCS thrusters: [![RCS thrusters](https://i.stack.imgur.com/k2hkx.png)](https://i.stack.imgur.com/k2hkx.png) Water vapor is easy to make when the ground is made of ice and you have nuclear power. Don't bother with hydrogen and oxygen: just superheat the water and explosively blast it out of a nozzle: the easiest way to store hydrogen and oxygen is in the form of water. Local materials: Well, you're good on fuel. Everything else would have to be imported or slowly fished out from the ice's mineral content through electrolysis, dew point separation, or whatever ends up being more efficient. There's a good amount of carbon down there, and plenty of hydrogen, so you could conceivably make plastics through a convoluted and power-hungry process. Some metals are present at impact sites, as well as silicon, which you could use to make ceramics. You might be better off importing though. It depends: if Europa is a fuel-mining colony, they can probably afford to filter their water for impurities as part of the refining process. If they're a research outpost, haha good luck! [Answer] This answers the original question as asked before edits. This answer does not work for a recently edited version of the question. --- You do not need any special fuel. You said that you have plenty of electricity that you are generating, so just use electrical motors. A good propulsion source on the surface would be wheels or legs. If the ground is solid, you use conventional means to traverse it. So, we use the same technology we have been using for thousands of years. A good propulsion source under the surface but still in the solid volume would be a drill. This could be either a conventional mechanical drill, or, since you have ample electricity, it could drill through the ice using heat; but beware, drilling using heat will leave behind water and/or water-vapor which you may have to deal with. A good propulsion source deeper under the surface in the volume which is believed to be liquid would require a sub. So you see, everything will just use types of devices that we are already used to, though they may need to be adapted a bit to the specific conditions of Europa. In fact, people have been working on this for years. See the following... [Robot Submarine on Jupiter Moon Europa is 'Holy Grail' Mission for Planetary Science](https://www.space.com/14997-jupiter-europa-ocean-submarine-robot.html) [An Alien-Hunting Submarine Is Being Tested in Antarctica](https://motherboard.vice.com/en_us/article/jpym5x/alien-hunting-sub-europa-artemis-stone-aerospace) [NASA’s New Deep-Sea Submarine Could Eventually Look for Aliens](https://futurism.com/nasa-whoi-orpheus-deep-sea-submarine) ]
[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/138799/edit). Closed 4 years ago. [Improve this question](/posts/138799/edit) Pantheism is worship that admits or tolerates all interpretations of deities. The human race exists throughout the multiverse, which was created and designed by God. Some are worlds that are completely run by democratic governments, while others are totalitarian empires that practice slavery. Some have cultures that lean toward matriarchies, while others are war-torn conflict zones similar to Mad-Max. All of these realms worship the same creator, but express that worship in different ways. Some see him as an all powerful, omnipotent deity, while others view God as different aspects that make up a whole, or multiple smaller deities led by a main deity. Angels are stewards of this god who exist to keep the universe functioning. They are similar to computer programs, which are written to make the verse work in the background, but are unable to interfere directly with the inhabitants. People know of these angels and the existence of their creator as fact. These beings operate with semi-independence. They can form their own opinions on matters, but must stick to their defined task and are not capable of disobeying universal laws.The angels periodically visit these realms and communicate with humanity at certain times during a millenia, but don't enforce any particular world view. Their job is ultimately to protect the versed from threats and keep it working according to the original design (fighting off stewards from competing gods, laws of gravity, etc). The problem I have is how these angels would interact with humanity and how they justify the worship of a God that has no rules of how to worship. Ex: someone asks them certain questions about world views or morality, such as whether slavery or oppression of certain races or lifestyles, or modes of governing. The angels can't just come out and say "God doesn't care how you worship it, just that you worship it". This seems inauthentic and indifferent, and may push people to just not worship God at all. Why would people devote worship to a god with no moral authority? [Answer] The exact same way it is done now, formal priests, or self proclaimed 'messengers' happily do the interpreting and make up the rules in each locale or even each small group. Anything that disagrees with them is a demon. [Answer] # Because God wills it so God is the omnipotent creator, right? So he doesn't need to send angels to explain his stance/apathy. He just burns it into the soul and DNA of every person. They know, instinctively, that God is there. That he demands their worship. That he doesn't care the method. Or about Human laws or morality. Of course they still have the free will to reject this. And it might be a plot element in your story that a few people are born without this genetic knowledge. And how the angels and others react to them. # Really high persuasion or intimidation checks You say it seems like people would not accept the answer 'God doesn't care about that' from the angels. But that really depends on your angels. Your divine programs could be the ultimate smooth talkers. They explain that God watches over everyone equally and without judgement. That he respects everyone's free will the same, even if Humans themselves don't. The angels words are so certain, clear, and convincing, the people believe them. Or, the angels appear as a burning pillar of solar fire. Their mere presence lays bare a Human's soul and thoughts and secrets. To doubt them, to question them, is to be destroyed. They proclaim God has no opinion on the matter, and Humans accept it, because to do otherwise is to be destroyed. Or, the angels just lie. They are there to keep the universal order intact, right? And God doesn't cotton to mere mortal morals. So just give the mortals what they want. Feed them a convincing and consistent line of BS about God's desires and rules, such that it makes it easiest for the angels to do their job and keep the universe(s) running. [Answer] # Your angels do their jobs. > > Angels are stewards of this god who exist to keep the universe > functioning. They are similar to computer programs, which are written > to make the verse work in the background, but are unable to interfere > directly with the inhabitants...These beings operate with > semi-independence. They can form their own opinions on matters, but > must stick to their defined task and are not capable of disobeying > universal laws...*Their job is ultimately to > protect the versed from threats and keep it working according to the > original design* (fighting off stewards from competing gods, laws of > gravity, etc). > > > They may form opinions on how close a society is to the original design or what to do about competing gods, etc. That's not the same as saying they have human levels of ethics or morality. Say you are a (minimalist and old fashioned) farmer. You have flocks of animals you set out to pasture. You check on them periodically to make sure they have enough water and that the pasture provides for their needs. You might repair the fences and make sure that your competition (wolves, coyotes, other humans) aren't a threat. Do you care about how the animals treat each other? Do you care which flocks rally around a matriarch and which around a patriarch? Do you care if some animals make other animals bring them food or force them to stand around swooshing off their flies? Does it matter to you who gets to be first in line for the water hole? Honestly, you probably wouldn't even notice. If you did, you might be surprised by the complexity and variety of behavior your animals display, but any interest you have would be that of a dispassionate observer. An anthropologist (or animal behaviorist). As a farmer, you might be moved by the plight of a particular animal that caught your attention. You might even intervene against bullying or slavery, what have you. But it wouldn't mean you were out to reform the system. Just that you sought to elevate one being (or perhaps a small group of beings) you felt something for. In the case of the angels, if their god boss doesn't give them instructions about moral behavior in humans, it seems unlikely they'd notice or care. If you chose to write a story about one angel (or a small group) becoming invested in human affairs, that's one thing. But I see no reason why it would just happen. [Answer] The answer depends a lot on the existential reason for why God exists at all. Suppose your God has nothing to do with humans at all, but in the maintenance of the balance that allows the very universe to continue to exist? Suppose a purpose of your God is to enforce the universal application of the Laws of Physics, to ensure they are never broken? To ensure that the universe continues in a predictable, rules-based fashion? Further, suppose the purpose of God is to ensure that entropy (universal equilibrium of all energy) never occurs? That is, God does not care what humans believe in. God is not narcissistic. The 'goal' of humans, from this perspective, is not to worship God, but to aid God in the quest to reverse entropy. That is, if there were no God, eventually the universe would degrade to complete equilibrium. However, under the direction of a God (intelligence) this degradation to equilibrium is reversed. Life, and in particular humans, concentrate energy and build. The dynamic universe is forever maintained. So God does not care what the actual morality of human beings is. God is not interested in any concept of the 'soul' or 'goodness', only that humans continue to create, build, harness energy, and seek knowledge. That is, God does not care whether or not humans worship God, but only that humans continue to serve the purpose of God. Consider that it is humans that drive our desire to worship God, not that God demands we worship God. That the reason for human worship of God has nothing to do with God's desire, but is entirely in our nature as intelligent beings? We worship God because WE want to, or have a need to, worship God. The Angels, therefore, have neither the interest in nor the desire to promote worship of God. They just let humans be humans, while God carries out God's purpose. Once you free the notion of God from the notion of the salvation of the human soul, as some being who's only desire is to be worshiped by humans, and give God a non-human-centric reason for existence, a non-human-centric goal, one that does not depend on human worship (only, perhaps, human servitude), then you allow for a completely pantheistic (using your definition) God. That is, God does not care how you worship God, or even if you DO worship God, God only cares that you do his bidding, voluntarily and willingly or not. In this case, your function of the angels is exactly what you stated - 'Angels are stewards of this god who exist to keep the universe functioning.' As long as the universe continues to function (that is, entropy is never reached) they are fulfilling their mandate. Morality is not their concern, the continuation of existence of intelligence, intelect, and discovery is. ]
[Question] [ Unit Info: On a fallen world that has firearms and combustible fuels. Society is still advanced in a way, but is more tribal/feudal in nature. One nation has an armed order called the Iron Guard that protects the nation’s borders with deadly firepower and brutal force. But they were more defensive then offensive and really slow in movement (there wearing big heavy iron amour). If an attacking force sneaks past them it would be hard for the Iron Guard to pursue the enemy, so the Iron Rangers were founded. The Iron Rangers unlike their name had little in the way of iron amour only a mask and a iron breastplate, but made up for it with cunning and skill. The Iron Rangers are used as scouts, saboteurs, and all around man-hunters. The recruits are from all over the nation but most of them are from Redstone. The reason for this is that the hardy people of Redstone have pet Crows that they use to hunt other people with. The Crows Info: The Redstone Crows have been trained in a way that makes them seek out other humans. When the Crow spots a person and or group they will start to sway side to side in a pattern that when a Ranger sees will know that there are people that way (helps the Crow from not getting shot also). Even if the Ranger doesn't see this when the crow comes back it will be agitated and very vocal, a clear sign that the way it came has danger. If the Crow doesn't come back at all, it is also a "very clear sign" that there are people in the area... that are well armed and good shots. The crow will not react to other Iron Rangers and Iron Guard in the area because of the masks that they wear (turns out crows are very good with faces and can tell friend or foe). The Question: Could Crows be used for Recon Would love to see if this could work and if there are any drawbacks in using Crows for recon. As always, if you want any more detail don't hesitate to ask. [Answer] Have your crows be independent contractors. The flock chooses to associate with the humans and does recon of its own accord. The voluntary association of corvids with large predators has been well described. <https://owlcation.com/stem/The-Raven-and-the-Wolf-A-Study-in-Symbiosis> > > What I meant specifically, was that ravens tend to go hand-in-hand > with wolves that hunt rough terrain for their own needs in way of > food. Ravens will also be in the area of licensed hunters, as well as > poachers, which can make the poachers very easy to locate, since they > are generally about the area during off-season for hunting. > > > Crows cannot open large carcasses alone and need help from large predators. One reads of crows / raven following armies for that reason: meat. The crows signal where potential prey is and then follow the predator to it. Probably these sorts of interaction work best with social predators like wolves or humans. --- The coffee is working well for me this morning. The character of Crowfeeder stepped into my mind. A noncombatant because of age, or gender, or caste, or inclination, she follows the warriors. After the battle she strips the enemy dead and prepares them for the crows: opening the skin, cracking the skull, and with the help of her mule hanging them in the trees. The story writes herself around her: she is alone, an untouchable corpsehandler disdained by the humans with whom she travels. But she is loved by the flock - and so has access to the crow world and the worlds at its borders. She interacts with the dead and the dying, and in doing so learns their secrets. [Answer] I would say yes, with some caveat. First things that comes to mind is that somebody else already attempted using crows for scouting in fictional works: his name was Noah and he sent out a crow to search for dry land after the flood, and the crow never came back. Mythological works apart, crows are rather smart birds, and have been reported using tools and passing that knowledge among generations. I have personally seen crows dropping walnuts on my windows to crack them open (the nuts, not the windows). As the OP suggests in his comment below here, they can be conditioned to be faithful to humans. Another thing that the above story suggest is that a crow not coming back is no sure sign of other humans around. Crows can be hunted also by other predators, or fall victim of incidents. Moreover, knowing "there are humans somewhere" is no big info for a scout. It would be better to know also where, when and how many. To add another critic, humans are decent at spotting anomalies: a crow zig-zagging above my head would quickly rise my suspicion. I think it would be better if your trained crows would simply circle above the humans (like they were looking for food, easily found in human garbage), and then leave, heading back to their human masters, where they could report at least on the direction of the scouted party, and maybe even on their number (think something like hitting the beak once per spotted person). [Answer] We have used pigeons for recon work. If pigeons can do it, surely crows can too, right? During WWI and WWII, pigeons were outfitted with cameras by both sides in each war. > > [I]n 1932 it was reported that the German army was training pigeons > for photography, and that the German pigeon cameras were capable of > 200 exposures per flight. [...] Although war pigeons and mobile dovecotes were used extensively during the Second World War, it is unclear to what extent, if any, they were employed for aerial photography. According to a report in 1942, the Soviet army discovered abandoned German trucks with pigeon cameras that could take photos in five-minute intervals, as well as dogs trained to carry pigeons in baskets.[26] On the allied side, as late as 1943 it was reported that the American Signal Corps was aware of the possibility of adopting the technique. [WP](https://en.wikipedia.org/wiki/Pigeon_photography) > > > From the article, it appears that birds were used far more extensively for messenger duty than recon duty. But this proves the idea was used in a few cases. There are photos of the birds, outfitted with cameras, at <http://twistedsifter.com/2012/05/history-of-pigeon-camera-photography/> This site also includes some of the photos the birds took. ]
[Question] [ So I'm still wondering if humans could survive with dinosaurs. There are some big problems I see. Here they are: # Food Production [![enter image description here](https://i.stack.imgur.com/7DF4w.jpg)](https://i.stack.imgur.com/7DF4w.jpg) This isn't so much a problem with planting and the plants growing as it is with big herbivorous dinosaurs eating the plants including the fruits. This would be a major problem, The tallest herbivorous dinosaur is Sauroposeidon at 18.5 meters tall. This means that to guarantee that food is produced, the fence surrounding the civilization would have to be just a little taller than Sauroposeidon is. But more likely is for ceratopsians such as Triceratops and stegosaurs such as Stegosaurus to eat all the plants including tree saplings to the point that no food is produced than for a very tall sauropod to eat the leaves of a tall tree. # Predation [![enter image description here](https://i.stack.imgur.com/hYEFA.jpg)](https://i.stack.imgur.com/hYEFA.jpg) This is possibly the biggest problem of all of them. If humans are just starting a civilization on a planet that is full of dinosaurs, it is inevitable that big carnivores like T rex would find them with their great sense of smell and vision. But humans don't weigh much compared to a T rex and probably would not be a threat or prey to T rex. Height of a T rex would be up to 5 times taller than that of a human. A much more likely predator is something like Utahraptor, about the height of a human and about 10 times as heavy. That or possibly a juvenile T rex. # Domestication I honestly don't know if dinosaurs could be domesticated for protection or to help the humans hunt. But I do know that the big dinosaurs(as in bigger than a human in height) that could possibly be domesticated, would pretty much all be herbivores. So assuming some technology is given to help humans and the plants they grow not get overheated, could a human civilization survive on a planet full of dinosaurs given that there are all these major problems like predation and herbivores eating all the plants that would be producing food for humans? EDIT: Okay, quite a few people have asked what technological level the humans are at. Well these humans were on a generation ship before so I would assume space age level. Someone has also asked for which dinosaurs there are on this planet. I don't think I can specify every single dinosaur but I do know that on this planet are dinosaurs from the Triassic, Jurassic, and Cretaceous that aliens have transported from Earth to this planet that they have survived on to the modern day. [Answer] I am pretty sure humans would deal with the problem in the usual way used when colonizing any other land: lead the unwanted species close to extinction, then enclose the remaining ones into a protected area and cry environmentalist slogans. Don't forget that naked apes equipped only with stick and stones have been able to take rid of some nasty beasts like the saber tooth tiger, the mammoth, the cave bear. Some slow growing dinosaurs with no human intellect are no serious treat to a determined group of sapiens. [Answer] The difference is we can adapt over generations Dinosaurs have been on the planet for 250,000,000 years. Modern humans have only been around for around 300,000. It is a question to this day as to why dinosaurs did not create evidence of cities, technology and cultivation. They certainly had the time to do it - in comparison we humans have achieved these things in a fraction of the time they existed on the planet. One theory is that our ability to transfer knowledge down generations, instead of simply within one, was the revolutionary step to allow knowledge to slowly accumulate and grow in time amongst us. Strong family structures, and later social structures, are thought to enable this to happen, evidenced in primates even today (chimpanzees are known to teach their young several technical skills to enable food gathering). This may be a quality unique to mammals, as reptiles and other animals seem to not readily demonstrate ability to teach their young new skills they learnt in their lifetime. It is easily conceivable if this ability is still present in your scenario, for knowledge to pass down generations. The nascent human society would grow in technical ability similar to what we have already witnessed (keep in mind we also had predators and difficulties in food production, yet we were able to adapt to these over time). Dinosaurs or not, we would simply adapt to their presence and develop techniques over time to 'work around' them. As Darwin said, the species that adapts is the best placed to survive. [Answer] Well, talking about broad questions. If you send people off to colonize a planet, you will provide them with everything they will be needing at least to create villages, hydroponic greenhouses, shops... If I were the mind behind the ship, I would make sure that the ship itself can be stripped down to its last piece to be reused on the surface. At this point, the infrastructure will not be a problem. Defense and Hunting: colonists will be needing weapons. Much as fancy laser gun are a narrative temptation, we must not forget that these guys will be needing as low tech as possible, in order to provide themselves with spare parts. They will have everything they need to learn how to build a new electronic industry, but first they need to survive and assert their dominion in the chosen area. Welcome back, Mr. Smith & Wesson! Funny enough, dinos, or at least whatever megalitic species is living on this brave new world, won't be the real problem. You are armed, they are big, soon the weapons will make the difference. Also, with one catch you get abundant meat, clothing and other useful organic parts... No, the real catch on this planet will be germs, microbes, viruses. The colonists will be exposed to a plethora of stuff their immune system is not wired to react to. They will have to purify everything before eating or drinking it, make a lots of tests with their animals (sorry!), and even then the first morsel will be a risk. Sure, they will be having all the instruments to analyze stuff, but I wouldn't bet on a safe first period of their new vacation. [Answer] For space-age humans, even colonists that do not have a foothold yet on the planet, dinos will not pose a very significant threat. The larger dinos in fact would present less of a long term problem because their numbers and reproduction rates would necessarily be lower. If they are causing problems we will simply cull them. More troublesome might be smaller rodent-analog ones, but they too are unlikely to pose existential threats. The native dino population would likely be a great benefit as a source of ready protein-rich food though. [Answer] There is this youtuber called tierzoo discribing differnet animals and races in depth and in comparison ranked in tiers, maybe you can inform yourself about that. > > <https://youtu.be/v6yY9HKVmfA> > > > <https://youtu.be/nwx8hP_nIn0> > > > <https://youtu.be/ImYu9dJM4kQ> > > > <https://www.youtube.com/channel/UCHsRtomD4twRf5WVHHk-cMw> ]
[Question] [ Please avoid the obvious jokes. Now I know there are different versions of the Greek monster Typhon, so first I will try to describe its properties. 1. Incredibly large roughly 50-100 feet tall, although I believe some versions had it human-sized 2. Appears to take the form of a large storm or tornado. In other words if you looked at the creature you wouldn't think it was anything other than a tornado or cyclone although at other times it might coalesce in some manner to appear like a giant humanoid. That is pretty much all I know regarding it. There may be other sources on the creature. Irregardless I am curious how such a thing might evolve or exist biologically. I know most sources say it was mountain sized in the stories but that is biologically unsustainable short of something machine augmented. So I am imagining something more on the scale of a dinosaur which is at least from a sheer mass standpoint sustainable in an ecosystem. A list of all of the Anatomically Correct questions can be found here [Anatomically Correct Series](https://worldbuilding.meta.stackexchange.com/questions/2797/anatomically-correct-series/2798#2798) [Answer] What comes to mind for me is some type of hive mind. Perhaps Typhon is a collection of small insect sized creatures that are capable of flight. The closest real-world alternatives I can think of are ant colonies or bee hives, where the entire group works toward one goal. Obviously, your Typhon would have to have a much stronger connection than an average bee hive, but the central idea is there. This would help explain Typhon's disparity in sizes, as its size would change based on the size of the swarm, and would also allow you to explain the destruction that it causes as the swarm feeding, (extra points for the swarm being carnivorous or omnivorous). As for how Typhon could've come about, that's the tough part. For this you might want to look at locust swarms. Every so often conditions become perfect for the this particular type of grasshopper to enter the "swarming phase." Basically it hulks out and gets with a few million of its friends to destroy every plant it comes across. So maybe Typhon is something similar. You could even have it be a normal insect that we have today that suddenly finds conditions to be perfect for it to enter a swarming phase. Maybe conditions haven't been right since the time of the Ancient Greeks who saw it and developed the mythological creature named Typhon. For this to evolve there would have to be some advantage to swarming like this, so maybe it vastly increases the amount of food that each individual can get for a certain amount of time, while also allowing them to breed at an increased rate. Eventually this would become unsustainable and the swarm would dissipate until conditions become right for the swarming phase to start again. This could lead to an endless cycle of the insect swarming and destroying everything in its environment, completely ruining the ecosystem and maybe rendering it uninhabitable, returning to normal for a thousand years or so, and then swarming again. Who knows, maybe the Sahara desert was one the Sahara forest before the first Typhon swarm began? [Answer] While Typhoeus (or Typhon) was a monstrous storm-giant, he didn't exist as a storm, instead he issued forth devastating storms from that dark nether-realm There are multiple descriptions of Typhon, but one element that most of them have in common is [serpent-like appendages and features](https://en.wikipedia.org/wiki/Typhon). Combining the various descriptions of him would likely result in a giant humanoid (or humanoid dragon) with 6 snake heads from his shoulders (potentially more from his hands) along with a possible, second Dragon head (in addition to his own), and large bat-like wings and horns -- but again, there's no exact description of him. [![One of only a few depictions of Typhon](https://i.stack.imgur.com/3hvjF.jpg)](https://i.stack.imgur.com/3hvjF.jpg) According to [Nonnus's Dionysiaca](https://en.wikipedia.org/wiki/Dionysiaca), Typhon features more snakes than other descriptions (a "tangled army of snakes"), and stated that "every hair belched viper-poison" and that he "spat out showers of poison from his throat". This might potentially give him the ability to cloud himself in a toxic cloud, or storm. So, if you went with the most common, mythological version, it wouldn't be too difficult to have it exist as a fictional, anatomically correct monstrosity. However, if you're referring to Typhaon instead of Typhoeus -- that creature was indeed described as a hurricane. However, [Hesiod](https://en.wikipedia.org/wiki/Hesiod) was the only Greek poet to separate these names and account for two different creatures. Every written instance afterwards combined the two descriptions into the single creature known as Typhon or Typhoeus. ]
[Question] [ So I was thinking of a land animal with a biological harpoon, I'm not 100% sure why it would evolve with it. Details of it would be: * Quadrupedal * Medium-sized (similar to a pony) and would hunt smaller or equal sized prey * not limited to being carnivorous, could be omnivorous * Harpoon isn't one time use, will be retracted to be used again The closest I can think of is the cone snail which uses toxin and a harpoon appendage to catch prey due to it being really slow. The creature I was thinking off wouldn't be THAT slow and if having such a harpoon would have any place in its biology. We don't see harpoons on land animals for a reason unless I'm missing something, perhaps an insect has it but I'm not 100% sure. Question: how would a harpoon be a better hunting tool for a land creature than other things we see like claws and limbs for grasping? [Answer] The principle is viable but not normally used as a penetrating weapon. Consider the [chameleon's tongue](https://www.youtube.com/watch?v=z3oh73amxQo). It's a projectile weapon that adheres to the target and retracts to bring in prey and be reused. The question here is whether that's a valid hunting method on a larger scale for a non-tool using species. Nature, by virtue of only using it on a small scale probably says no. Let's look for a critical weakness. This is the only way the chameleon hunts, it's an ambush predator with a tethered weapon. That tether is life or death if it gets cut. Most large prey, of a size suitable for feeding a panther sized predator, is quite capable of doing significant damage to the hunter. Whether by horns, hooves, or teeth, if you sever the tether the hunter dies. [Answer] 1. Biological harpoon means fighting at close quarters. Detachable harpoons back in the whaling days had floats and such to keep track of where the whale went. And hopefully the whale would exhaust itself trying to escape. An injured whale smart enough to go after the boats a la Moby Dick would be hard to beat. You do not want to fight a whale at close quarters until it is dying. So with your creature. A biological harpoon is unlikely to have a hundred years of line. It will be a lot shorter, and so if the harpooned creature cannot get away and finds itself still in proximity to the predator it might turn and attack. Your creature must be formidable without the harpoon. It wants to fight at close quarters (e.g. crushing bite or something similar) and the harpoon enables that. Reeling in the harpoon to get the prey close should be a desirable effect. 2. Reusable is nice but harpoon should be potentially disposable. [![cat claw](https://i.stack.imgur.com/wvTkb.jpg)](https://i.stack.imgur.com/wvTkb.jpg) from <http://pictures-of-cats.org/my-cat-lost-his-claws-please-help.html> A claw is a nice example. The blunt outer part is shed periodically to keep it sharp. If the claws stick in prey and are torn loose, ok. The harpoon should be a keratin structure, maybe with hair or other easily regenerated fibers tethering it. If the harpoon line gets cut the predator needs a new one in short order. In fact, and thinking about claws, this predator might have several harpoons including a couple that a growing and some buds where new ones will be. It might decide to deploy additional harpoons once the first is away. Or it might decide to ditch the harpoon if the prey is looking too fierce or (think water buffalo) there are other individuals coming to the rescue and the predator must beat a hasty retreat. An even better real analogy for this is a porcupine quill: already big, already barbed, already disposable and regenerable. A big porcupine quill with a tether. Your animal is a giant porcupine which is an opportunistic predator. [Answer] Snails have appendages called "love darts" (gypsobelum) that they fire at each other during mating. These darts are grown by sexually mature snails and contain a hormonal substance which can be "fired" at the intended mate with a muscular contraction and which then helps to ensure that the shooter's sperm has a better chance at surviving inside the mate. This is the closest example I could think of for an animal with a "harpoon" that was not simply a horn or a stinger. Perhaps your creature is some variety of large terrestrial gastropod that has evolved their love dart to also be used as a weapon? As to what advantages this method of hunting could have, there is the obvious advantage of a ranged attack keeping a safe distance between the creature and its target, perhaps the hormones within the love dart might produce an allergic reaction in other species? [Answer] Reason why we haven't land animals (beside ourselves, of course) using harpoons are: * harpoons need considerable force to be effective and that isn't easy to develop gradually. * harpoon tether is likely to be attacked by prey and vulnerable to breakage, which would leave attacker crippled. * something [similar](https://en.wikipedia.org/wiki/Cnidocyte#/media/File:Nematocyst_discharge.png) is available in water but they are neither reusable nor long distance. [Answer] First let's define a harpoon. It's a hard sharp shootable object that pierces the target and can be reeled back in. We do have stuff similar to this already. A chamelion's tongue is somewhat like that but it's not hard and does not pierce the prey. I'd say say an evolved version of this would probably look like a hardened hooked tongue tip which can extend out from the creature's mouth. Another form of a harpoon would be something like a scorpion's tail but with a much longer tail part. You could go with an evolution of either of these. ]
[Question] [ I've become interested in sci-fi / science-fantasy / weird Westerns. Building upon what I asked [here](https://worldbuilding.stackexchange.com/questions/90756/why-colonize-a-planet-without-the-continued-benefit-of-modern-technology/) I would like to be more specific and ask if there's scientifically sound ways to explain why a human society's (as in a colony) state of technology might be locked to say 1870s North America. Background The sci-fi Westerns that I know are the first book in the "Dark Tower" series by Stephen King and the TV series "Westworld". The former doesn't bother to explain why people use old tech in a world where more advanced societies using more advanced tech have existed beyond that they perished somehow. There's magic present here. The latter takes the approach of a Western styled theme park with androids for NPCs in what is essentially a LARPG and is scientifically accurate with no magic present. Two possible explanations I see two ways. One is simpler and presents an easy answer, one more complex because science plays a role. The latter I'm seeking an answer for. As pointed out in the link above they might simply be forced by another group of people on or off the planet they inhabit to use old tech such as to keep them enslaved. The question that immediately comes to mind would be: Why force them to use 1870s tech and not say 1500s tech? A simple answer might be: For the captor's enjoyment. Same as people in Westworld pay to enter the theme park to experience the Old West (safely), the captors might treat the captive's day-to-day struggles like a reality TV show filmed by advanced drones and such. The other and the one I'm more interested in would be that the planet's chemical composition prohibits them from evolving beyond America's state of technology of the 1870s. Say due to technological issues they can't use the technology that got them to the planet and that started the colony using frozen embryos and artificial wombs. The knowledge transfer using computers brought on the ship or capsule failed (e.g. due to them breaking) and after a couple hundred years given a colony of a big enough size they arrive at the state of technology of the 1870s. This leads to the Question Is there scientific reasons why they might not be able to progress from there? Is a planet scientifically possible that will be habitable and enable 1870s state of technology but which prohibits humans to progress from there due to its chemical composition? A semi-rational scientific explanation would be just fine. I'm not sure if the Second Industrial Revolution that began in the last third of the 1800s was based on natural resources different from the ones used in the early to mid 1800s. If they are not, a scientific explanation might not exist and I would have to "go back in time" within the 1783-1920 period of the Old West myth. I like both concepts for my world-building purposes but I'm just curious if there might be a scientific explanation that removes the need for a "prison-theory". [Answer] I will propose a novel, two-pronged scientific solution. [electrical, biological] Bear with me for the first part, I will explain! ### Part 1 Lots of natural chromium, lead and mercury, perhaps titanium; and virtually zero gold, copper, silver or other good conductors. That could be due to previous mining or just the natural result. It does not have to extend to the core: It could just be true of the first few miles of crust, the human-accessible part. You can help this somewhat by not having volcanoes or plate tectonics on the planet. Reference: [Metals That Are Poor Conductors.](https://www.reference.com/science/metals-poor-electrical-conductors-332baad80f738d5a) The combination of iron and chromium is a conductor but one of the worst metallic conductors. (about 80 times less conductive than copper). Lead and mercury and titanium are also dozens of times less conductive. So why the focus on conductivity? Naturally conductive metals were crucial in our discovery of electricity, which is far and away the single most important ingredient to getting past the 1870s. Without cheap conductivity, we don't have wires, which means no electric transmission, no electric motors or generators (they need copper windings to create electromagnets), no electric lights or communications. No air conditioning or elevators, no arc welders. No phones. (Likely no telegraph either, an 1870 element that would have to be excised). This does not prevent them from developing hard carbonized steel (for guns, axles, etc), but carbonized steel (or stainless steel) is an even worse conductor. [![Conductivity Ranking](https://i.stack.imgur.com/IecRb.png)](https://i.stack.imgur.com/IecRb.png) Without high natural conductivity, you also have a low incidence of natural magnets (lodestones). High tech could obviously refine metals and produce better conductors, but if everything conductive on Planet X is more rare there than Gold is on Earth, this is a non-starter. Imagine if the copper-wound motor in your kitchen blender had to be made of solid gold; or if the power lines leading across the city to your home had to be made of solid gold. To enable the *beginning* of the modern age, conductivity has to be cheap. You could still have, made from hard metal alloys (with low conductivity) steam engines, guns, farming tools, axles and so forth. Some industrialization could take place. ### Part 2 This is not absolutely necessary, but you could introduce a unique biological element that helps this along; a soil bacterium ubiquitous on Planet X that metabolizes conductive metals and forms as waste molecule sized compounds that are less conductive (like iron and chromium), or perhaps oxidized, and diffused in the soil. This is to make it more difficult to refine. IRL [Aluminum was once this way on Earth:](http://knowledgenuts.com/2014/02/27/the-metal-that-was-once-worth-more-than-gold/) > > Aluminum is one of the three most common elements found within the Earth’s crust. However, until relatively recently, extracting aluminum from the bauxite ore in which it naturally occurs was a costly and difficult process. And prior to the advent of efficient chemical and *electrical* processes to separate aluminum from bauxite in the late 1800s [specifically 1886 and the *electrolysis* process], the shiny, flexible metal was more valuable than gold. > [emphasis on electrical and bracketed detail by Amadeus] > > > It may be a little hand-wavy without further research, but IRL we have bioengineered bacteria to produce and concentrate all sorts of materials. It is reasonably plausible that bacteria could evolve that help to make metals very difficult and expensive to refine even if they are very common atoms within the crust (like aluminum would be still, if not for electrical extraction methods). ### The Result A society with metal but no economic incentives to advance to an electrical society. IRL electricity and magnetism was very much an expensive novelty in the age of Steam. If conductive metals were as costly as gold, it never would have advanced beyond that; and we would not have developed the modern age of electrical communications, broadcasting, computers, refining, HVAC, forging, and so on. We would have older methods of forging metals; and coal (and oil) could still provide heat and fuel. The steam engine would become more refined. Yet we would be, very much, locked in the pre-lightbulb era, IMO much like 1870 (without the telegraphs). [Answer] Insufficient Population or Population Density Your colony started out with tens of thousands of people. They were fruitful and multiplied, and now there are almost a million of them. Why, the capital city/starport has almost 50,000 inhabitants. * There is an university in the capital. They teach agriculture, engineering, medicine, law, and so on. Unfortunately the last x-ray machine in the teaching hospital broke down a couple of years ago, and nobody in the engineering department can jury-rig a suitable replacement. * There is this weird guy who claims that he will build a heavier-than-air aircraft one of these days. His latest airframe is almost up to WWI-era technology, but his attempts to come up with a suitable engine all failed. No avgas and very little gasoline, for that matter, since trains and electrical power plants all run on coal. * There are two "steel barons" on the planet. Or it might be better to say that there were two steel barons. The Colonial Legislature ordered them to stop their petty feud (72 patent infringement lawsuits in one year!) and to work together. Now there is one project to build an open hearth furnace instead of two separate ones to build smaller Bessemer converters. Needless to say, the furnace is over time and over budget, too. You might recall the story how two guys in a bicycle workshop invented the aircraft. But they did not have to fabricate all the parts in their little workshop. They could fly because they stood on the shoulders of industrial giants. For many industrial age processes, the best size is very big. Compare Mao's [backyard furnaces](https://en.wikipedia.org/wiki/Backyard_furnace) with the [Krupp](https://en.wikipedia.org/wiki/Krupp#Alfred.27s_era) works. [Answer] There is nothing in Nature that can prevent scientific advancement because "objective" reasons. There are, however many "subjective" reasons that can lead to that effect, at least for a certain amount (possibly large) of time. A few examples: * Lack of interest: research about alternative energies was (and partially still is) hampered by ready availability of cheaper alternatives (no funds for research). * Politics: research about alternative energies was (and partially still is) hampered by groups and individuals who have interest in current technologies (buy technologies and bury them). * Religion: in dark ages (especially in first centuries) some scientific hypotheses became "doctrinal", so challenging them could lead to being burned at the stake. Take your pick. [Answer] Something similar was made in 1984 by George Orwell, even if the society presented there was stuck in the 1950s. (spoilers) Basically, 1984 is set in a dystopian dictatorship. The Party (the government) stays in power by continuously monitoring the population's thoughts in varied ways. One of these methods is by locking their cultural and scientific progress, since The Party believes that cultural and scientific advances would "awake" the population to its state of semi-slavery. The solution found is to have the country in a constant state of war. Since all of the nation's production is directed to the manufacture of weapons, soldier training, espionage and similar activities, no one has time to think about anything and there are no advances in any technological or sociological field. This is a viable strategy to lock a society in a state of technological inertia, but there are somethings to consider: * It requires a constant, never-ending war * It requires that the enemies in such war are also technologically locked, otherwise they would defeat the locked nation purely by technological superiority. * In 1984 there is a long and continuing history of the liberty of thought being attacked. The usage of a language called "newspeak", for instance, is also very relevant, as it limits what kinds of thinking are possible. The state of technological inertia is caused by many factors working together. One solution I can think for your setting if you don't want a war is to simply fake it. Maybe all of the ammunition made is dumped into space and the soldiers are killed as soon as they finish training. Edit: I remembered that 1984 itself says that war was not the only way to achieve a complete stop in technological and cultural development. Any other excuse could be used, as long as it directed all of the nation's productive power into something else. However, war was the most viable solution, since it placed the population in a position of mass hysteria, making them easier to control. [Answer] The colony exists only to produce raw materials for the empire. The empire doesn't want them producing more advanced manufactured goods, because it'd threaten the home world's monopoly on those goods, and because colonists might want to work in better-paying and less dangerous factory jobs when the empire needs them in the mines. The empire doesn't want them having advanced weapons, in case they want to secede. Technologies like film or telephones are also banned because anti-imperial forces might use them for propaganda or organizing. Education is very limited, and travel outside the planet is prohibited, so nobody gets any bright ideas like "democracy" or "revolution" or "independence", which also has the side effect that people know little about scientific advancements on other worlds. [Answer] The two things that powered the Second Industrial Revolution were electricity and fossil fuels (petroleum in particular). Fossil fuels are easy to get rid of. The desert planet never had enough biomass to turn into fossil fuels in the first place. There doesn't need to be no fossil fuels at all, mind you, only too few that are easily accessible to power mass industry. How did it get its oxygen, then? Maybe there was some biomass, mostly bacteria, but not enough and not the right type to create significant fossil fuel deposits. Maybe oxygen was created by the initial colonisation effort, for example by implanting an ecosystem well in advance and/or with atmosphere processing stations. The stations may have fallen to disrepair since, the atmosphere has been transformed now. There are also a few abiotic reactions that can produce an oxygen-rich atmosphere, though any natural atmosphere would probably require some tweaking to be human-compatible anyway. Things like heating and steam engines can be powered by organic sources like wood. It will not be enough to power a full industrial revolution, because that would require more forest than can fit on the map (which is even worse for a desert planet, though human density is probably lower as well), but you can still power a few systems like steam trains with it. What about electricity? Amadeus answer is pretty good there, and there is another possibility: geomagnetic storms. In 1859, there was solar storm big enough to fry telegraph systems. <https://en.wikipedia.org/wiki/Solar_storm_of_1859>. It is speculated that a few thousand years ago, an even worse solar storm hit. (As an aside, if you need background for a post-apocalyptic story, one of those could hit tomorrow and fry pretty much every single non-shielded electrical system on Earth. The only warning would be giant aurora as visible as far as the Caribbean about 24 h before, as the dangerous particles have a lower velocity and thus arrive later.) If the planet is around a star that is more unstable than our Sun, then the planet could be regularly hit by giant solar storms. Aurora would happen often and be spectacular, and the star itself would probably have more variation than the Sun, which may be why turned the planet into a desert in the first place. Maybe the planet was a lush world some distant time in the past hundred million or even billion years, before the star became unstable, producing the atmospheric oxygen. The fossil fuel deposits could have disappeared of become inaccessible due to tectonic activity since them. Note that tectonic activity require oceans, though, but the continents may be desert even in the presence of oceans. Beyond that, geomagnetic storms probably have negligible effect on life, apart from the rare Earth-based lifeforms that use magnetic fields for orientation. ]
[Question] [ ## What happened It's late 2017, and aliens finally arrive on earth. They're very happy to meet us because we're the first civilization their generation ship encounters, and they freely share the two technological devices that allowed them to travel for thousands of years: the "Zero-Point Engine" and the "Energy-Matter Converter". The instructions to build them are given to every single state, and they can even replicate themselves, so they quickly become widespread in the whole world (but are still government-regulated, a private citzen can't own one). ## New technology The "Zero-Point Engine" generates a constant amount of electricity from nothing. The "Energy-Matter Converter" is an electric device that (almost) instantly materializes any blueprint, no matter how complex (think limitless 3D printer). It has no problems producing food or organic matter, in fact you don't need to create blueprints from scratch, as it is equipped with a scanner and will be able to produce exact copies of what you scan. It also has drones to make big things like buildings, cars and such. ## The problem Humans obviously need regulations on what they can/can't build, so I need some sort of "Replication Credits", to regulate the usage of EM Converters. However, most people are left unemployed: all of manufacturing, ore extraction, agriculture (and more) is now useless. There still are careers that resist and are even required: administration, research and developement (any field), hospitals, programmers... So I am in a society that still has the need to work, but the majority of people are unemployed and they're not even expected to find a job. How can I distribute credits in a fair way? --- Things I already thought: Daily amount of credits: This would be unfair to those that work. Why should I work if my neighbor that does nothing gets the same? If we introduce paid work instead, we get inequality in the other direction: How should I get a job to gain more credits, if there are no jobs for the great majority of the population? And let's get real: most humans must be forced to work for profit. Voluntary work exists, but is usually not long-lasting and not what society really needs in that moment (I still have to see voluntary data entry clerks or voluntary cleaners). Job rotation: This would allow me to retain paid jobs, but would introduce a huge amount of problems, as there would be an immense hit to productivity and quality. --- ## The end result The great problem humans would face is lack of space and regulamentations on how to use your own ground. My story will see humanity trying to overcome that by building giant space "shells" around earth, and will revolve around the colonization (and building) of those first giant ecodomes. It's particulary important for me to figure out what exactly people on earth are doing to earn their abitable space and build things, as this will heavily influence how and why people get the right to colonize this new environment. [Answer] As a whole, I think you are overestimating the impact of your invention on employment and you are painting a picture that is worse than what it actually might look like. Europe is currently heavily debating basic income: <https://en.wikipedia.org/wiki/Basic_income> . If a human is useless for whatever reason, you can still give him some credits, but maybe not as many as others get. Even though I'm not an advocate myself, I don't think it's as bad for a society as you think. Please be aware that this might even create new jobs. Just because we can make up things doesn't mean we immediately do it in the most efficient way. This might actually be more of a "3rd world problem". I think it might even be worth discussing this for the 3rd world specifically, but I chose not to because we would be here all day. But here are some general thoughts: a) Make up jobs. Several countries have done this in the past and continue to do so. Just give people meaningless jobs. Here for some inspiration: <http://www.huffingtonpost.com/entry/man-skipped-work-for-6-years_us_56c1d32ae4b0b40245c72512> b) Do not use technology. This is what for example the Nazis did. It's kind of similar to a), but you still do some actual work - it's just not as efficient as you have to. c) Restrict the access to that technology. This happens somewhat with genetics in agriculture for example, people hold back to "save jobs", but it's a bit of a stretch maybe. Somewhat related is market protection. Countries sometimes try to restrict products from countries that produce cheaper in a number of ways. This still could be done in your case. d) Subventions. I'm sure politicians didn't die out over night. The EU is keeping its whole agricultural sector alive that way even though it would not survive in its current form in a free market. Now directly related to your idea: e) You would still need a lot of people. Concerning the things you replicate and so on: there will be waiting periods, there will be trial periods, things will break and you still need to develop stuff. I think it's obvious that what those devices will create a lot of jobs long term, but even short term you still need for example plumbers or electricians and so on that know what those machines need to create. People will not end up on the streets overnight with your idea. f) Consider that you need to redo your infrastructure. That would employ a LOT of people pretty quickly. We might actually be dealing with too few people. g) You will need a lot of jobs for communicating what is needed. Every field has its own "world of discourse". You need experts on one side that tell people what to produce with those machines, you need people to operate your machines and replicate stuff and you need the middle man that speaks the language of both parties or things will go horribly, horribly wrong. h) There will still be a lot of jobs in retail or even wholesaling. Just because things are available for very cheap and very fast doesn't mean everyone knows any product and what to buy to solve what problem and what is on the market. Even restaurants might still work because blue prints can still be secret - and now the same goes for factories. Look, this can go on and on. There are so many ways which means your question is a bit broad atm. One could address the situation in mining communities in Chile or in the suburbs of London and so on and the answers would always be different. Also keep in mind that long-term planning might be very different from what is needed short term, I read your question as mainly short-term because of how you put it. I tried to keep it as general as possible, I hope it is somewhat helpful [Answer] The resulting economy might not be that different after a little stabilization process. You still need (and want to pay credits to): * politicians, diplomats * public administration and regulation (where what to print for whom to use) including patent attorneys * printing and distribution of goods and accompanying consultation (a government printing shop in each street?) * health and care worker, teacher * firefighter, ranger, gardener * police, surveilance and military jobs (especially if all countries can now print nuclear weapons) * creative jobs (designer, scientists, architects, writer, composer, singer, dancer, terraforming engineers ...) * craftsman ("rich" people will want to have something unique handmade like a wooden table, a ceramic coffee pot or a paved driveway) * construction worker (even if you can print out highways and airports, someone has to work the printer) * pilots, chauffeurs, guides for airplanes, trains and museum visitors and many more. But the "stabilization process" might be longer or shorter, simple or complicated, with no or billions dead, depending on your story. [Answer] You know what would be the first thing some states produce? Weapons. A lot of weapons. Bio-weapons, chemical ones. I think some even would try to duplicate fantasy guns and prototypes. Anyway, I think that P.K. Dick wrote a novel about exactly same scenario. People were paid for doing things. Like getting 8 hours of sleep - which gave enough credits to pay for rent. Brewing own coffee instead of buying one at a machine. Cutting grass by themselves and so on. Of course they could get additional "regular" job to have more credits but just sleeping and doing mundane task gave them enough to pay for rent and food. But to add to that the jobs that would be most valuable would be the ones that make unique things. Artists, writers, poets. Something like the clique of youtubers that spend their trust money on fast cars and then make 100 videos about how fast it is. [Answer] I have the impression that the replicator is not the most important of the two gifts, but the generator is. We can already fabricate next to anything, and definitely can produce anything any ordinary person needs almost all of the time. But what we all need, all the time, in (virtually) limitless amount, is energy. Energy in the form of food, or fuel for heating, fuel for moving, both us and the goods we (think we) need, to light up the darkness, to cool on hot days... it all boils down to energy. Creating anything that is needed is just a nice commodity compared to limitless and clean energy. Admittedly, I would still love to get one of those replicators... But to your question: How would jobs change? Jobs in services will be unaffected. This means teachers, nurses, doctors, bankers, salespeople, you name them. Jobs in manufacturing will see some change, and a lot depends on the constraints of your replicator. Today, additive manufacturing is really cool, but it's not economical for large quantities of simple things. You can 3d-print your own plastic cup, any shape you can imagine, any color you can get the filament, any size your printer can handle. Printing time will be a couple of hours, a day max. Or you buy 20 plastic cups at the next store for half a dollar or such... Additive manufacturing excels at very complicated shapes, and very small amounts of objects, but it's fairly slow for ordinary shapes. So, depending on how (and how fast) your replicators work, it might still be more sensible to create steel bars for construction in the old way. But I assume we will soon see the death of the entire fossil fuels industry, like coal mining and oil and gas drilling, shipping, and refining. Also, energy efficiency will all of a sudden be hardly any concern, only for off-grid devices (like mobile phones, aircraft, ...), but at the same time we might still keep wind and solar power generation, not only because we already have it and see no point in dismantling a working power plant that does not pollute anything, and for plain old backup. What we might see is actually less military jobs. We even have a potential for fewer wars and crises. Digging up uranium for your nuclear power plants simply doesn't make sense any more. What little of the stuff you need for spacecraft and medicine you can create nice and clean and hazard-free in the replicators, saving you all the hassle of corrupting other people's governments to cut a profit from the resulting unrest. While some people might complain about the loss of a market for small arms and ammunition, I find it at least conceivable that the general public might frown a bit more on such actions when the price for their convenience goods is no longer dependent on other people's loss of human rights. So, to sum it up: the energy sector will change beyond recognition, some industry will change, and the services sector will remain unaffected. [Answer] > > Daily amount of credits: > This would be unfair to those that work. Why should I work if my neighbor that does nothing gets the same? If we introduce paid work instead, we get inequality in the other direction: How should I get a job to gain more credits, if there are no jobs for the great majority of the population? > > > But replication credits only give you replicable items. So given empty land, I can build a mansion. But without the empty land, I have nowhere to site my mansion. So along with replication credits, you still need real currency to get land, etc. You would get a job to purchase things that can't be replicated practically. Or access to such things. Jobs would primarily be scientific and engineering. Given the design for a new robot, you could replicate it. But who would design it? And who programs it afterwards? Those design and programming jobs would be where the money would go. And most people would want to learn how to do that. Because even if you don't do it for others for pay, you want to be able to design and program a robot of your own. ]
[Question] [ Say someone has invented a time traveling device and he can go anywhere on earth in the very distant past. Where could he leave a token (any object or marking) on earth that could be discovered in the present as proof to himself that he went backwards in time. This should be something that the traveler could leave in the very distant past, like a million or so years ago, and must be something that could be found again without an unreasonable amount of effort. For a little added simplicity, let's say the token can be any material, real or fictional, of any shape. [Answer] Make a small, hollow cylinder of Technetium, which is only available on earth (in visible quantities) as a byproduct of nuclear fission of uranium or plutonium -- and is radioactive (for ease of relocation.) See: <https://en.wikipedia.org/wiki/Technetium> And hide it in a bore hole drilled into an easily-relocated, not easily accessable spot on Uluru (formerly called 'Ayer's Rock".) While Tc-99 is the most available (from nuclear fuel reprocessing), but Tc-98 is more stable (half life is over 4 million years), so the cylinder should still be nice and radioactive for detection. So let's use Tc-98. Ballpark cylinder dimensions: (25 mm diameter, maybe 300 mm long, 5 mm wall thickness.) Adjust the outer diameter to be a couple mm less than the selected rock drilling bit selected. Hollow with welded-on endcaps; weld closed only after adding the message on a suitably durable medium. For the message itself, I'd use stainless steel (say T316, unless you insist on more Technetium; I wouldn't), which is available in a wide variety of thicknesses, and rolls nicely, so long as not too thick. Ballpark 0.010" (or 0.25 mm) should work. If you can find it (and get it etched!), you could also use Platinum foil, which ought to hold up even better. Also make a spacer, in case the driller {see below} has slow reactions. Same diameter as the cylinder, ballpark 10 mm should be plenty. {I would never do the following, but it would IMHO solve your question.} Go to Australia. With a pneumatic rock drill, drill horizontally into the the northern-most, steep face of Uluru (known previously as Ayer's Rock): <https://en.wikipedia.org/wiki/Uluru> (which is old, old rock {precambrian even?} and has been exposed for a long time as well.) Drill a slightly uphill borehole (5 degrees, for drainage in case of erosion) higher than reachable with anything less than a 25 foot (8 meter?) ladder, at least a meter deep. Place the message cylinder in the hole, followed by the spacer and tamp them firmly into the hole. Measure the remaining depth once the objects are placed and then patch the hole with epoxy mixed with the drilling tailings. This mixture, plus the hard to get to location should hide the patched hole from anything short of detailed inspection. --- To recover the time capsule (and prove you must be a time traveller): Using saved survey info (and/or photos), use a geiger counter/scintillator to find the patched hole on the sandstone monolith. Erect a scaffolding to work from. Use the next larger diameter drill from when you drilled the original hold. Mark your drill with the known maximum depth, prior to starting to drill. Be aware that the rock face has eroded, and you don't know how much, so be careful doing the following: While monitoring the drill shavings for metal, drill or dissolve out the epoxy/sand patching mixture (again using a pneumatic rock drill, or electric if you prefer), remembering to stop drilling when one sees metallic shavings! Extract the cylinder and amaze the world! Yes, you can drill the hole larger if you brought the right drillbits with. Or dynamite (this is fiction, recall) For best effect of your capsule opening, go back in time to somewhere before 1936 (when traces of Technetium were first discovered and verified.) I'd go back before the first atomic pile was invented (late 1942) for the most impact. The container proves the date. The message could be anything you feel safe writing -- but beware of the butterfly effect! PS, the spacer doesn't have to be Technetium. T316 stainless is again my choice. [Answer] A gold plate with his name carved in it. Leave it in a known archaeological strata which hasn't been disturbed until recently. Plenty of those can be found with a bit of research. Could even inscribe a short message 'Joe Bloggs travelled back through time from 2017 and left this plate here for xxx reason. HI MUM !!' [Answer] If you're allowed a time-capsule I think this is probably the best bet. Choose somewhere you know gets dug up before you were born (this way someone won't jump to the conclusion that it is a hoax) and include some random information that they might not understand yet. For example, a time capsule with a carved plate saying: "You won't understand this yet, but on the 17th of April 2017 at 15:30(GMT) call me, Brian Woodbury, on 07765432198" (I've no idea if that is a real number, I just pressed random numbers) And bury it in a site you know is uncovered before you're born because otherwise someone can say "Hey, what is this kid playing at...nipping in and burying a fake relic...pfft." and ignore you...or at least have a lot of skepticism around it. The danger is that this changes the past and someone else wants to get your phone number or name because news of this gets out. You rely on the finder/some organisation keeping it secret for years until you're born. There are a lot of risks...but then its timetravel, no one said it would be easy! [Answer] The Moon. * We know exactly where the astronauts are going to land. * No possibility for someone to secretly swipe it. * No geology or weather to move or bury it. * Lots of attention paid to the Moon landing and surroundings so many people would be aware of discovery. It would be hard to hide it or hush it up. The astronauts would read it to Mission control and hundreds of people would hear it. Gold plaque could state Armstrong's "one small step" quote, and the date of the moon landing. That would prove knowledge of future events without changing much. He and the other astronauts would find it and read it hours after he actually said it. The plaque would also state explicitly what it is: a plaque to prove that a person from the future traveled into the past. What, you can travel thru time but getting to the Moon is tough? Lazy! [Answer] Create a large 'man-made' diamond and cut it into a spectacular shape such that people would instantly see its value and not destroy it or cut it into smaller diamonds. Etch it using a laser such that without a microscope people couldn't read the engraving. As another answer said, put it in a well known cave system so it would be found by early spelunkers. Let it be found by ancient Egyptians, Chinese, or other early civilizations and it should attain a symbolic status and put into a museum for safekeeping. It could even change the course of history in that tribes or countries would fight over it. If you just show up with a or other artifact that has something etched on it they would likely believe it was a hoax. It needs to be something that has a history that everyone knows about. [Answer] # The Arctic 1. Figure out where they have drilled ice cores for scientific studies. 2. Get a gold plate. Put things on it. 3. Go back in time and leave it at the predetermined location. 4. ??? 5. Profit. Why the arctic? Because the last ice-free era was around 2.6 million years ago according to [this article](http://www.slate.com/blogs/future_tense/2014/12/02/the_last_time_there_was_this_little_arctic_ice_modern_humans_didn_t_exist.html) I literally just googled to find. > > The study provides new evidence that the last major gap ended about > 2.6 million years ago > > > So you'll have very little geological change there compared to other places on earth. Why gold? Because short of leaving it in [zinc or mercury](https://www.quora.com/Does-Gold-corrode-or-degrades) it won't corrode or degrade over the million years it needs to survive. I know you said it could be a fictional material, but a non-fictional one works well enough, so might as well go with that. [Answer] Find a deep cave to hide in/ Put something metal in one a cave far from the surface. Many limstone caves are more than a million years old. There is no natural metal in them so with a metal detector you could find the right stalagmite without having to smash the whole place. Or you could shape the ceiling to drip at places of your choosing, after a million years those drips will become pillars, and you can spell your name using pillars as pixels. It might not be recognizable without mapping. Some caves are still not fully explored, and seem to have been stable for a long time. You could leave your gold on the floor safely in an unseen side tunnel. Getting there without the time machine could be tricky. For the time capsule gold is a good bet because it doesn't corrode. Wrapping a rock that has the writing means even if it gets banged around a little you don't lose the message. ]
[Question] [ So I'm wondering if it would be possible for humans to live healthily on a largely Earth-like planet that was covered almost entirely in salt water. Landmasses would all be islands, with only a few reaching sizes of, say, 300,000 km$^2$, and the rest being around half of that or less. These landmasses would mostly appear in groups, with only two or three of these groups comprising most of the land surface on the planet. The islands would be varied ecologically, but the variety of habitats would be similar to Earth (regarding plants, animals, environments, etc). All in all, I don't imagine more than about 2% of the entire planetary surface would be land. I'm mainly wondering what the atmospheric implications would be, i.e., would humans be able to inhabit these islands in large populations (at least so far as natural resources allowed) and actually breathe? Obviously, there would be far fewer trees given the lack of land, so there would be less oxygen produced via photosynthesis. But if the landmasses were grouped closely together, thus lending their collective oxygen output to each other (if that's how it works?), and there were plenty of trees on many of these islands, and there was a substantial amount of marine plants such as phytoplankton in the oceans producing their own oxygen (they already produce around 70% of the Earth's oxygen), would humans be able to flourish? [Answer] # Humans will be fine Fortunately, [70% of the oxygen](http://www.nationalgeographic.org/activity/save-the-plankton-breathe-freely/) generated by plants comes from phytoplankton. [71% of the Earth's surface is water](https://water.usgs.gov/edu/earthhowmuch.html), so water and land photosynthesizers are basically tied in oxygen production. I would not expect much difference between your world and ours. If you integrate over time, the photoplankton have actually been much more important, since phytoplankton were generating oxygen for around 2 billion years before land plants got into the game. They (the phytoplankton) are responsible for bringing the Earth's atmosphere to its current composition, by generating oxygen and driving off the methane. So, again, there won't me much difference between your world and ours, as far as oxygen goes. [Answer] Earth initially got its oxygen from the [Great Oxygenation Event](https://en.wikipedia.org/wiki/Great_Oxygenation_Event), which was a period in earth history when photosynthetic life began to flourish and change the chemistry of the atmosphere. If this planet underwent something similar then you have all the pieces in place. With a large oceans you have plenty of space for that oxygen producing life to maintain a oxygen rich atmosphere. [Answer] Well, positing photosynthesis in the ocean, I don't see why not. Land masses don't have any kind of special effect on the atmosphere. The weather is a different matter. The weather would not be fun. Without large land masses to take power away from them, hurricanes will be stronger and last much longer. Any land life better be able to dig into or hold onto the land very tightly. The one thing that land masses (on Earth) are good for is providing nutrients to the coastal communities as soil gets washed down rivers. Though, you can get the same thing from upwellings from the ocean floor. The main thing to consider is the general depth of the ocean. On Earth the oceans tend to have more biodiversity where they are shallow (which also corresponds to being near land masses). [Answer] Such a planet may have oxygen.. but the problem may well be CO2. On Earth, carbon dioxide is regulated on very long timescales by the balance between chemical weathering and volcanic emission. That requires large land areas and especially large mountain belts. Without those, there may be no mechanism for removing CO2 from the atmosphere on geological timescales, so the planet would tend to 'go Venus'. Water worlds do not have stable climates. ]
[Question] [ Humanity is often said to have 5 senses, but this isn't entirely accurate. This is one question of several in a series I am asking regarding going beyond the 5 senses. [Magetoception](https://en.wikipedia.org/wiki/Magnetoreception) is one of the others. It's strongest in birds (although there's some debate about that--there's evidence that they use a kind of sound sonar to actually navigate). > > The mechanism for this is not completely understood; it is theorized > that this has something to do with deposits of ferric iron in our > noses. This would make sense if that is correct as humans who are > given magnetic implants have been shown to have a much stronger > magnetoception than humans without. > > > If I were building a race with an expanded version of this sense, what would the advantages be evolutionarily? From what I have looked at, navigation is the big one, but I don't know how else it would help and what the advantages might be. [Answer] Depends partially on the planet. The stronger the magnetic field the more precise the sense is. Now if certain animals would have a large enough magnetic field this would be a clear advantage for a hunter. Any other advantages really are just linked to navigation. Either migration or sensing very specific routes around hazards. Perhaps gathered by trail and error, much like ants. Another good point might be poor visibility. Either weather or underwater etc. This limited visibility would give a superior sense of navigation a clear advantage. Same in a dark cave system. Perhaps local ore deposits would be landmarks. After most evolution would've stopped we get obvious advantages with technology. [Answer] I don't know about evolutionary advantages, but I do know of an interesting example of magentetoception. A powerline worker underwent an experimental surgery, embedding a bunch of very tiny magnets in his fingers. When his hands got near a high voltage AC power line, the magnets interacted with the magnetic field around the wires generating a small current to be detected by his neurons. The result was impressive: he could tell if a line was hot or not simply by bringing his hands near the line. [Answer] It does not look to me that magetoception would have any evolutionary application apart from navigation. In nature, magnetic fields can be associated with large deposits of (typically iron) ore - but for species that we have here on Earth, these ore deposits do not make any difference - ore does not provide food, shelter or pose any danger. However, we can imagine an iron-poor world where available iron gets accumulated by the living organisms and deposited after they die. So, these iron deposits become an oases in otherwise barren landscape. Species of this world might develop a sense for finding such oases and navigate between them. [Answer] One advantage is that it makes you [somewhat sensitive](http://www.nature.com/news/electronics-noise-disorients-migratory-birds-1.15176) to radio waves. A more advanced magnetoreception sense could give you reasonably fine radio sensitivity. This could further help with navigation, allowing you to sense deep-space radio signatures during the day. It could also be used to sense lightning that is invisible to the naked eye. That could be useful in an area with heavy storms. And of course in the modern world it would be both very useful and very irritating. [Answer] Creatures which can perceive magnetic fields might be able to detect storms. In a circumstance where powerful storms (of different types) are a threat, the ability to detect them coming and seek shelter would confer a survival advantage and so evolutionary benefit. Thunderstorms. Everyone knows thunderstorms have lightning and where there are powerful electric phenomena there are induced magnetic phenomena. Thunderstorms can kill via lightning, flooding, tornadoes or high winds. [Linked](http://onlinelibrary.wiley.com/doi/10.1002/2014RS005566/abstract) is an article describing far-ranging magnetic fields which might alert sensitive creatures to an incoming storm. Dust storms It has always seemed to me that dust storms should have more associated electrical phenomena that thunderstorms, by virtue of the nonconductive particles of sand / dust rubbing against each other. I know that dust storms can have thunder and lightning too. [Here](http://www.sciencemag.org/news/2016/07/static-electricity-strengthens-desert-dust-storms) is an article describing how the static electricity within a dust storm serves as a sort of feed-forward loop, augmenting the storm. As with thunderstorms, electrical phenomena mean magnetic phenomena. Earth storms aka earthquakes. It would make sense that the movement of large magnetized pieces of the earth's crust would generate magnetic fields. It is theorized (but I think unproven) that magnetic waves due to these changes can precede and possibly [predict earthquakes](https://www.newscientist.com/article/dn2395-electromagnetic-signals-can-predict-earthquakes/). How does that confer evolutionary benefit? I am reminded of the story of elephants which sought high ground in advance of the Indonesian tsunami and so were not washed out to sea or drowned. In an environment where earthquakes lead to tsunamis, landslides or other threats to life, the ability to detect them and seek high, flat ground would lead to increased fitness. Solar storms We are protected to a large degree from these by our magnetosphere. But should that change, or on a planet where that was not the case, or on a planet where solar storms were more severe, the ability to detect one coming (and hide deep underground!) could definitely confer a survival advantage. [Solar storms](https://en.wikipedia.org/wiki/Geomagnetic_storm) induce big changes in the earths magnetosphere, which would be detectable. I can imagine a magnetically tuned ancestor whimpering deep in a cave during the solar storm while its untuned conspecifics strolled merrily about in the sun, the incoming radiation mutating their gametes. [Answer] It's all about plumage. If acquiring iron, or avoiding the Zapper beasts, is a survival benefit, then mates will be drawn to those demonstrating the survival benefit. Literally. Those that can draw the mates with magnetic powers will draw the mates. ]
[Question] [ I'm writing a story in which a cloud of grey goo is entering the solar system and humanity must prevent any particle of it from reaching Earth (and potentially other worlds too). Alternately, I need a way to deal with grey goo after it has landed and begun spreading, but keep in mind that it would be intelligent and actively working against humanity. The diameter of each nanite is on the order of 100 nanometers during travel, making them hard to detect. The cloud more or less spans the solar system but is primarily centered on the planets. Going in humanity's favor is that this cloud is extremely thin—only a hundred nanites or so will be on a collision course with Earth. Also in humanity's favor is that they can be a lot more technologically advanced than 2016 Earth. (But not in the distant future! Within 50 years is best.) Molecular manufacturing, fusion power, and jovian space stations might be a reality. Is it possible to manufacture an event horizon shield? Maybe that's a viable option, though I'm imagining railguns and lasers. Going against humanity, however, is that this cloud is moving at relativistic speeds. They have little warning—maybe two months since detecting its effects in deep space. Yes, imagining a nanite like that 'landing' on Earth without exploding might be improbable, but I have some ideas for that. In summary, humanity must, in two months or less, make preparations to destroy ~100+ nanites of 100nm each heading towards Earth at speeds of .9c or more. Potentially without knowing the nature of what's coming. I.e. That they are nanites. Secondary is preventing them from landing anywhere else; Mars, Jupiter, the asteroid belt, Sol. [Answer] In order to set up defenses, you need to know what you're up against. The first observations will be those of a dust cloud moving at 0.9c, and as interest increases ("how did it get moving so fast?"), it would turn out to be more metallic than expected. At this point a large portion of space-based telescopes will be aimed at the cloud, and they might start detecting communications between the nanites (assuming they communicate using radio (or at all)). People might start to realize that it's a nanite cloud, and once it's been confirmed, humanity would be scrambling to analyse the communications. If the data is encrypted, hacking the network would be hard, if not impossible. Although the encryption would be at the cost of latency. Otherwise, if it is possible to hack the nanite network, there are 4 options. * Increase transmission power to drain energy. * Increase transmission power for better targeting. * Disable the nanites. (maybe there was a kill switch installed by the creators in case the swarm attacked their own system?s) * Redirect them. (might not be fast enough given that they are moving at 0.9c) Not much energy would be needed to disable a nanite, and a heavy-atom particle beam would do the trick (diffraction is very low, so high accuracy/long range). If humanity had managed to increase the transmission power of the nanites, the particle beam would not need to be as powerful as it would have to be if the nanites were transmitting at normal power (or not at all), as it could be more focused. [Answer] Um, guys, there isn't a problem here with nano-machine infection. There may be a radiation problem, but probably not. These things are coming at 0.9c, or faster, yes? So their kinetic energy is equal to about 80% of their mass energy. The situation we have here is a lot of very small versions of [xkcd What-If #1](https://what-if.xkcd.com/1/). When they hit anything, such as an atmosphere, or even a very thin gas cloud, they're going to be torn apart into very small blobs of plasma. The energy released in a collision is orders of magnitude above their nuclear binding energy, never mind the chemical binding energy that holds their various atoms together. They were probably spotted as a collection of small and brief gamma-ray bursts from the same direction. I have no idea how we're supposed to know that they're nano-machines at this range, and it doesn't matter anyway. They can't slow down enough to make a difference. They'd have to convert 80% of their mass directly into kinetic energy to do it, and that's an impossible level of efficiency, and leaves them without enough mass to be a convincing nano-machine seed anyway. That was always implausible, because at 100nm across, they only contain about a million atoms, which makes storing as much as a million bits of data (128Kbytes) in them highly implausible on quantum-mechanics grounds. 128KB doesn't seem remotely enough for a seed for grey goo. Now, if there were a lot of these, we'd be at risk of their killing us by the radiation released from their collisions. But if there are only about a hundred that will collide with Earth, there's no problem. It will be about like a hundred instances of the [Oh-my-God Particle](https://en.wikipedia.org/wiki/Oh-My-God_particle). Spectacular for astronomy, but harmless. [Answer] The problem is that individual nanites are far too small in far too large of an area to pick out indivdually. Anything like a laser defense system is simply unfeasible. We need to think wider, with forces that can affect a wide area without needing to know the nanites' exact location. The two that come to mind are radiation and electromagnetism. For instance, perhaps you can setup a series of gamma bursts radiating in the direction you think the cloud is coming from. While the nanites likely have some degree of protection to radiation, hopefully they can't handle the radiation from nearby nukes going off. Coincidentally, "a bunch of nukes" would be my solution for dealing with nanites landing, too. The other possibility is electromagnetism. If you can setup a strong enough field, you might be able to incapacitate the nanites, or simply redirect them away from the earth (and being nano-sized, it wouldn't take much force to veer them completely off course). [Answer] It's all about detection. If we can see them we can try to hit them with big bombs, burn them with powerful lasers or try to push them around with magnetic fields. Even one landing on Earth wouldn't be a problem if we could detect it before its colony dispersed very far, we have a lot of nuclear weapons laying about and we can always build more cities. If they are forming a cloud of sorts they probably talk to each other. If they do over space relevant distances we can probably detect it once they get near, and with how many antennas we have triangulation should be possible. Unfortunately you say they are smart, so once some of them die some others will try to be stealthy, and we haven't got a chance of detecting a nanite pretending to be dust. As for the other planets the situation is even worse. We can't even get to mars with only a few months warning so even if we have stuff over there it will be on its own, and I doubt space weapons are a priority for any colonies. And if they take a planet they probably would relaunch in [uncountable](https://xkcd.com/865) numbers from there in aimed attacks at the rest. We probably don't have the resources to fight a [Kardashev Type I](https://en.wikipedia.org/wiki/Kardashev_scale) civilization and certainly don't have the firepower to destroy a planet they take. [Answer] Question contains 3 incompatible premises 1. it would be intelligent and actively working against humanity 2. cloud is extremely thin 3. this cloud is moving at relativistic speeds. they are incompatible in following combination: 1+2+3, 2+3 they are valid in following combinations: 1,2,3, 1+3, 1+2 * with the premise that they do work on principles which are already known to us, if not then resistance is futile, and the only author may save the planet and the system, by any plot he likes. ## Defense 2+3 The first thing to do is to think about where it comes from because it can't be from a far away, and to think about why this pointless thing just happens. Except that, do nothing - they will burn on collision as John Dallman [pointed](https://worldbuilding.stackexchange.com/a/61709/20315) They are launched not from far away, or they are part of a way much much much more a bigger problem, galaxy sizes, something just enormous even for me, who argues about the viability of disassembling of planets in this century, and for which dismantling Jupiter in 100 years is not fast enough. It looks more like an invasion from another galaxy by enormous force, or someone is testing this civilization at close proximity, some thoughts [here](https://worldbuilding.stackexchange.com/a/41975/20315) starting at "Where is a big thing, though." Smaller the system is, and more complex tasks it has to accomplish - more fragile is the system. Probability of collision of 100nm particle with hydrogen atom of [interstellar medium](https://en.wikipedia.org/wiki/Interstellar_medium)(at lowest 0.2 particles per cm3) is about 2e-09 chances per 1 m traveled. 10% chances not to collide and 90% chances to collide with one hydrogen particle is the 1'151'292'514m distance traveled or it is slightly more than 1/150 a.u. Ok, let say one collision isn't fatal for it but traveling 1 a.u. mean high chances to get about 150 of such collisions, but let say it has a probability of 0.5 to switch off that unit after 150 collisions, damage it completely. And I'm very generous here because one act of fission is enough to evaporate that thing into a small plasma cloud. Which will form some kind of protective layer for the rest of them, a bit later about this situation. So in the worst case scenario half-life of the front layer of that cloud will be 1 a.u. or about 500 seconds(as it moves with speed of light). Calculate half-life of the cloud is a more challenging task, as plasma from front particles will shield the rest of the cloud, but still, this cloud will wear out because of some particles will sneak inside the cloud, and because that plasma shield will ablate too. But at some extent we may have examples of such cloud, there are clouds after supernovae blasts, as an example <https://en.wikipedia.org/wiki/Crab_Nebula> and such > > It has a diameter of 3.4 parsecs (11 ly), corresponding to an apparent diameter of some 7 arcminutes, and is expanding at a rate of about 1,500 kilometers per second (930 mi/s), or 0.5% of the speed of light. > > > <https://en.wikipedia.org/wiki/Supernova> > > Such extreme catastrophes may also expel much, if not all, of its stellar material away from the star,[5] at velocities up to 30,000 km/s or 10% of the speed of light. > > > Gravity pull is the smallest percentage for breaking force, most of the pulling force comes from the interstellar medium. By other words thin cloud at relativistic speed without forming a more complex structure to protect itself is incompatible with intelligence in this galaxy, or you will notice it by how all stars in the galaxy are dimming, as they(GGC masters) prepare to launch that cloud. It is like shooting pump gun underwater. # Defense 1+3 This will be a problem. And this problem will be not the: ~100+ nanites of 100nm each heading towards Earth at speeds of .9c But more likely some more complex structure, which is divided in chunks proportional for masses of all significant bodies, including the star (but really it depends on the size of that GGC system, it can't be too small though, or it will have problems to slowdown in our system) Traveling as a bigger and more compact(dense) system allows to reduce of the deterioration rate of the system and allows it to repair itself etc. 1% of the sun mass at 0.9c speed is enough to evaporate our system completely, and take all heavy elements (everything except H), use H as a propellant and travel further. 2 waves expected - one evaporates the system, another collects separates extract elements from that cloud. The effect will be similar to supernova. The time between waves, 1-100 years. The first wave may be anything, not necessary GG, just hydrogen cloud. And this thing will be seen from far far away, in the first place because it consumes the energy of previously dismantled systems. defense - take all bio-samples from the earth, evacuate libraries and people, and head in the perpendicular direction from that thing, and pray for your gods. Another way is to try to take control over that thing, but the most likely the star system will be lost, because it may be impossible to stop the attack even after gaining the control over the system. ## Defense, more like OP it wishes, earth. The main part here is that you have to have similar systems. It is pretty hard to do something with a stone against a tank, not impossible, but it is not likely that something good will happen there if there are no proper/matching tools that can be used. Individual units of GGC are not a problem. They may be a bit tougher than usual microbiological live but hard gamma will efficiently disinfect them, the same way as it used for medical instruments disinfection. They still need an energy source, and energy source will limit them how fast they can grow etc. Attack them, cut their energy sources. This way if individual particle lands on earth somewhere you have to detect it, and do it fast enough(days, month, years). And it highly depends on which kind of disguise it may use. But small unit probably can't use any kind of disguise, because it is not native infection which spreads trough living things (they are most abundant sources of energy which is easy to extract from, another alternative is sunlight) Sunlight will limit their grow speed by 100W per square meter on average. Consuming biological matter may be a faster way for them to grow. But as a small unit is most likely dumb as usual microbiological life, and it can be noticed by observation from satellites. Both cases can be observed from satellites. Also, entry trajectories will be seen because of gamma rays generated during the descent and it will help to determine the place of its landing. Tool from [this](https://worldbuilding.stackexchange.com/a/45273/20315) answer, starting from "Note about Venus scrap, snake elephant" can help to detect those particles fast(in different ways, let say just cover overall planet), most important it may help to fight those GG systems and it is less advanced (as I think) in creation as a molecular assembly. The strength of Gray Goo is not in the capabilities of a single nanite, but in a system which it may create from themselves(or other matter as well) en masse. The difference is like to compare a human consisting of a big set of cells and some microorganism consisting of one cell. And if it is intelligent, it will be intelligent not as single nanite, but as significant size system of those nanites. But rules of physics still apply to that system, essentially it needs energy and its capabilities will be limited by available energy. Most energy comes from sunlight, biological materials on the surface, gas/oil in the earth's crust. GG is not some kind of an unstoppable force, a doom whatever. The problem begins when someone is too late to apply countermeasures when it is grown bigger than someone's capabilities to counteract it. Coordination, observation, energy sources control, fast enough reaction - are keys to eliminating the problem at its start, at its source. * [Here](https://www.reddit.com/r/IsaacArthur/comments/54cmdn/titanium_what_metal_would_we_want_large_sheets_of/) is discussion and it drifted away from materials for space habitats to about discussing nanites threat, maybe will be interesting for someone. ## Defense, more like OP it wishes, space/orbit Single nanites can't maneuver, again they are useful as some arrangement of them, as a system of them. And as a big system, they may easily be an invading force even at 0.9999c, but as a cloud of single independent units, it is helpless. Just place a foil 100nm thick on its way and it will just annihilate. A gas cloud on its way will lead to the same effect. Basically take an asteroid and evaporate it with a thermonuclear blast or in a less spectacular way - grind it, spread the dust. Effectively, on average, it has to be like 100nm thin layer of foil(as the average density of that dust cloud on the way of nanites) to be as effective as that foil barrier. to protect the earth in the way, it needs 1'920'000'000 tonnes of water as an example, or 2-3 times more (by mass) tonnes of rocks. Thus an asteroid of 10 cubic kilometers of rocks will be enough if it is dispersed correctly. This method will work with single units up to pretty low speed, less than a few km per second (speed difference between a nanite unit and the shield, I'm just eyeballing that speed, maybe 10km/s.) # Defense against the carefully planned attack If they acting like a dumb swarm, it way less a threat compared to a situation of a planned attack against humans driven by an evil intelligence. If humans control the system(including Oort cloud), and all energy in the system, all matter sources, and attacking forces are not big enough and have less energy then available for humans - then humans can counteract. They may fail or may succeed. But if humans do not control the system and if initial invade force is small, the attack can be already happening right now, thousands of years, somewhere in Oort cloud, or on Gas Giants, as an example, Great Red Spot may be an observable mark of such attack, we do not know why it exists, and why it is red. If the attacking system will gain more strength than we have, then there will be no chances to stop the intelligent invasion, or a self-learning system, without to create a more efficient and faster-growing and intelligent system to counteract the threat. The only chance in this situation is to create a better system that is faster, more efficient, more intelligent, operate it in a better way than other intelligence. Everything boils down to Defense 2+3 case, it has to be understood what is the source of those attacking particles, the reasons for the situation. Are they just symptoms of an illness in the solar system or what, and how big is the problem really. [Answer] I cut this up in different parts: 1. The Travel 0.9c is not possible without an external power source, nor possible to slow down from without an external power source. Thus, I presume the most logical source of energy: radiation. The nanites could be flat, riding radion to speed up and slow down. Like solar sailing, though, they could ride any energy field. \Using this means much slower deceleration, spread out over months, easily doable. 2. Surviving the Trip At 0.9c they die before arriving. Particles cannot be wiped out of the way fast enough. Even if they shield behind a wave of a supernova. Decreasing speed makes much more sense in this regard. The point of artificial life is that it is in no hurry; it makes no sense to waste energy traveling that fast if you have eternity. As such I presume much slower speeds: 0.1c tops. Add a simple rotate ability (think a tube of 100 atoms long, 1 thick, 1 high) and most collisions can be evaded). 3. Intelligence I circumvent the storage issue by using links more like how a brain works. The order of atoms makes the data; the number of unique sequences within a 100 number is insanely high. That could be the passive coding, activating as communication as the nanites grew in number. Again nanites have time though, their brain processes need not go as fast as ours. Mortal lumps of meat need thousands of impulses per second; nanites can work fine with one one every thousand years. 4. arrival So now you have dust particles nearly undetectable since at best you pick up one communication impulse, and they appear dormant and have slowed down before you noticed them. Nothing you can do. At the much lower speeds the descent is much more doable. They might use the same solar sail tactic to parachute down, or just drop to the ground as given their small size the gravitational pull on them is marginal too. Likely the bodies with atmosphere and of smaller size are prioritized to land on. 5. Growth They have a sun nearby and energy they will start replicating but again they are in no hurry, they can use billions of years if needed to consume the solar system. As such the goo is relatively harmless. We won't detect it for millennia, but once we do it is neither an immediate threat nor a problem to contain. But presume they can speed up their normal slow reproduction if enough energy is available. It would make little sense to do as a standard tactic. The energy of the sun over billions of years outweighs anything else, so such a short rapid burst only makes sense to counter an immediate situation. ## Conclusions If peaceful it might defect life, and rapidly multiply to get to the numbers to communicate with us. (No threat) * If defensive it might counter danger by multiplying faster and/or relaunch part of their population prematurely. (Again no threat) * If offensive it might eliminate any threat to itself and if we are seen as such we will be killed since we cannot remove them all from all planets. As such, best defense would be: act peaceful, let it be. ]
[Question] [ An English speaking person has accidentally fallen through to a parallel world and is now stuck there with no hope of return. English and other Earth-native languages are not spoken there. As they continue to survive and (eventually) thrive in this new country, they begin to suspect that there may be other people from our world hidden within society: iPods, t-shirts and a few books in English have appeared at markets or as curiosities on display. They didn't bring them, but maybe someone else did. They have come up with the idea of humming or whistling popular tunes as a low-risk identification method. Which brings me to my question: which songs should they hum to be noticed by the broadest range of fellow travelers from Earth? Assume the following: The country they find themselves in is Tudor-ish in terms of technology, is very wary of 'foreign spies' and has a whole bunch of superstitions around magic. This makes speaking or writing a foreign tongue risky: you can be arrested for being a spy, hounded by a mob for 'spell craft' or thought of as mad. The tunes should aim to reach a broad a range of potential travelers from Earth, so limiting it to popular tunes within a country (eg national anthems) will potentially find less people than something more widely known. [Answer] So three songs come to mind. The ABC song, Baa Baa Black Sheep, and Twinkle Twinkle Little Star. Why? They're all widely known, often taught to children from a young age... ...And they're the exact same tune. Baring that there's possibly the most widely sung song over the last hundred years, Happy Birthday, or the record holder for the most played song, It's a Small World. Of course all of these are Western biased (although they include many Western cultures who's primary language isn't English). Unfortunately, there's no one tune that is widely known in the West, India, and China, meaning one tune won't work globally. However since we have the west down, let's tackle China and India, shall we? If we do, we should have a fair portion of the population covered and then we're playing a favorable game of statistics. For China, as best as I can research, Song of Four Seasons is the most widely known song across Chinese subcultures, and has historic stake so if you meet a traveler from a slightly more historic period he or she is still likely to know the song. [Give a listen to the song here](https://www.youtube.com/watch?v=QkOYbf2MF00). Indian music is a little different. I can't hunt down the most well known tune, but (as a Westerner) it has a very distinctive nature to it. Hearing Indian music I almost always known it's immediately Indian, even if I can't put a name to it. Why does this matter? Because even as somebody not of that culture, I have a decent chance of recognizing the tune as Indian if I heard it hummed. I'd only assume somebody actually from India would recognize the tune of their homeland. Don't believe me? [Try this song from the middle.](https://youtu.be/vTIIMJ9tUc8?t=37) Well there you go. You have China covered (1.4 billion), the West covered (seems to be about 1.5 billion), and India covered (1.2 billion). That's over 4 billion of our ~7.1 billion planet. If you alternate between these, you'll statistically likely come across another Earthling. [Answer] Anything from Disney, particularly their cartoon movies/ animated features. But it would have to be a snippet short enough not to draw attention to itself, but long enough to be not only recognizable. [Answer] Requirements: 1. Universal (not Western/Eastern biased) 2. Obviously Earth-originating to a fellow Earthling (cannot be brushed aside as coincidence) 3. Meaningless and harmless to a non-Earthling Tunes (notice that tunes that have been spread by multinational advertisements are going to be far more universal!): * Beethoven's Fifth opener (duh - duh - duh - DUUUUH) * McDonald's "ba-da-da-da-daaaa I'm loving it!" * Windows sounds * T-Mobile sound * Intel sound * Dog whistle *Primalistic or learned sounds* (often more universal than tunes):** * Baby crying, giggling, shrieking (this is the best one because humans have a universal primal instinct to respond) * Thunder * Police siren, ambulance siren, firetruck siren * Gunshots * Friendly noises: dog barking, cat meowing, cow mooing, frog croaking (this assumes these animals only exist on Earth) * Unfriendly (primal) noises: wolf growling, snake hissing, monkey shrieking (this assumes these animals only exist on Earth) * Firecrackers * Doorbell * Phone ringing * Motorcycle revving, plane flying overhead, cars going around a track *You may also want to consider non-audible signals:* * Google, Apple, Microsoft logo * A silhouette of a creature particular to Earth * A flag * A carving of a water bottle, car, lightbulb, bike, plane, gun (i.e., tech not originating from foreign planet) * Name-dropping some Earth-specific thing (like, "My brother's name is Ronald McDonald. He likes to make hamburgers, a funny type of sandwich.") * Being aware of scientific or mathematic concepts not known to foreign planet (such as calculus, relativity, internet, gunpowder, man on the moon) [Answer] Actually, I think the national anthems of widely militarily, colonially and diplomatically involved nations may be the best choice. Some countries national anthems are broadly recognized by just a few bars. So I would use: * Star Spangled Banner (US) * La Marseillaise (France) * God Save the Queen (UK) This should give you recognition for most everyone in north and south America, all of Europe, most of Africa, and southern Asia at least. Alternately, go with a movie that has a recognizable score and has been translated into the most languages and was popular in virtually every region of the world. Seemed like a tall order. My only real contender turns out the be the original Star War's (A New Hope). Whistling the main theme or Vaders Theme ought to do trick. [Answer] I keep coming back to the Beatle's. The yellow submarine in particular, and Elvis. Maybe more his physical impression. I know you don't want western specific, but some western music stars have a huge, absolutely huge following in India, China, and Asia. Karaoke, impersonators.role-playing, comic con. Didn't the prime minister of Japan pop out of a Mario pipe is cosplay outfit at the Olympic closing ceremony in Rio? They know the words of the songs, they know the tune. They might not know exactly what they singing but they know a good beat when they hear it. Whistling 'we all live in a yellow submarine' while walking down the street is hardly to draw attention. Unless whistling is a sign of the devil, as I have been told by one old Jamaican lady. Giving an Elvis impression while saying 'thank you, thank you very much' will raise eyebrows but hardly call the mob on you. Arnie's 'I'll be back!' is sure to be understood by anyone from the last 30 years even if they have never watched the terminator movies. 'and Elvis HAS left the building' might be a bit too western specific without some catchphrase action. You could also probably use popular movie movement's, like John Travolta's Saturday night dance stance. Or, cultural dances themselves. Ie, while I may not be able to imitate more than a very generic Indian music tune, I sure can imitate a Bollywood dance move! Ouch, now I have the worst song stuck in my head...Celion dion's themesong from Titanic! Ah, great, now its ' aannnndDDDDD EEEEYYYYYYYYEEEEEEEIIIIEEEEEE, will Alwayyyyyysssssss lovvvvvveeeeeeee yooouuuuuuU! ' I think the problem with national anthems and nursery rhymes, is quite a few of them are based on very old tunes. So while it may be a parallel world, surely they would have some shared history. 'god save the king/queen' is quite likely the UK national anthem in quite a few parallel world's. 'mary had a little lamb' or 'row row your boat' is so ancient it's almost prehistoric. Parallel world's are bound to know a few of them. Maybe not with those words, but the tune itself. Your other world jumpers have ipods and the shirts so you are not talking about people from a very long time in the past. Use something popular, from your time period. Humans are addicted to entertainment. Not many of them will acknowledge it, but they all have a guilty pleasure listening to that extremely overplayed popular boy/girl band. So popular that it transcends cultural barriers! [Answer] Perhaps the bet thing to use would be an advertising jingle from a global company, This would cut across many language and cultural barriers, since the parent company s establishing a global presence and a global branding. You want people to recognize your brand wherever they go. Perhaps the number one most widely recognized global advertising jingle would be "It's the Real Thing" from Coca Cola. As an advertising jingle, it is only a few bars long, so your traveller does not have to stand on the corner and whistle or hum a long or complex tune to identify themselves, and the countersign is equally short (just whistle back "It's the Real Thing"). This could be taken to the next level as well. Depending on how adept the person is, they might try to recreate Coca Cola (or at least some simulation) and market it. Only people in the know would understand the meaning of the iconic wasp waisted bottle, cursive script name or even the dark coloured, fizzy liquid within. [![enter image description here](https://i.stack.imgur.com/BL3RE.jpg)](https://i.stack.imgur.com/BL3RE.jpg) [Answer] The wolf whistle seems to be universally known around the planet. Maybe not a younger generation item but still has been known world wide is Whistling shave and a haircut (reply whistling 5 cents). ]
[Question] [ For a rather hard-science based sci-fi setting, I am checking for faster-than-light (FTL) possibilities. One option that I consider is the following: Interstellar travel is achieved through portals. They can be imagined during their construction as two giant rings initially superposed. Once finished, they are separated but have a remarkable property : they behave as a "tunnel" in space. Something watching or entering in the space circled by Ring A will see or exit through Ring B. No special effects or anything fancy : both parts of spaces are "simply" connected and behave accordingly. After that, you can move Ring B to anywhere in space, at slower-than light speed. Even if takes a few hundred years to achieve, you can end-up connecting stars or regions of space, building a web of connected portals. This system makes the portals key elements in my setting (for obvious strategy, communication, and trade/economic advantages) and avoid some FTL. I'd like to have Worldbuilding reader's feedback on this : * Is this something that is commonly used in existing settings ? * Is this plausible ? While not really hard-science, it avoids effective FTL by playing with the space shortcut, without any hyperspace involved. Any other remarks on this "pseudo-FTL" scenario are welcome. For clarification : this is a 2D visual representation of the resulting space-time : [![space deformation](https://i.stack.imgur.com/ZbLIz.png)](https://i.stack.imgur.com/ZbLIz.png) So there is no fancy glowing portal here : simply a permanent connection that is created between two regions of space. This is indeed nearly identical to a wormhole, with the specific characteristic that both endpoints must start in one single point. The initial "pinch/hole" can after that be moved. --- Hereunder is the initial unfortunate attempt to connect Earth and Mars, resulting in Earth's atmosphere leakage to Mars. By regulation, next gates were enforced to be located in outer space and limited gravitation/magnetic fields. [![Gate to Mars](https://i.stack.imgur.com/19e4M.png)](https://i.stack.imgur.com/19e4M.png) [Answer] What you're talking about is known as a [wormhole](https://en.wikipedia.org/wiki/Wormhole), and variations on it are actually pretty common in science fiction (partial list [here](https://en.wikipedia.org/wiki/Wormholes_in_fiction)). The only franchise I can think of off the top of my head that uses the particular version you mentioned is the Galactic Civilizations series of games, but I'm sure that there are many others. As far as we can tell, it's at least plausible, although there's a lot of argument about whether or not it would allow true FTL (your movement appearing faster than light to an outside observer) or apparent FTL (your movement appearing slower than light to an outside observer but instantaneous to you). For more information you can look at [wikipedia.org](https://en.wikipedia.org/wiki/Faster-than-light) and [projectrho.com](http://www.projectrho.com/public_html/rocket/fasterlight.php) (the latter website being an excellent resource for space travel in general). [Answer] This setup has a very slight problem - it forms a perpetual motion machine. Let's take two portals, A and B. Place A on the ground. Suspend B (oriented horizontally) 10 meters directly above it. Now take a mass M, place it 1 meter above A and let go. Oh yes, and let's put the whole thing a vacuum chamber, shall we? The mass will fall into A and appear at B. Since its velocity vector is vertically downwards, it will fall into A, reappear at B, ad infinitum. Each drop from B to A will increase its kinetic energy by Mgh. In the early stages it will gain about 14 m/sec in downward velocity for each pass through the portals. A 1 kg mass will gain 98 joules of energy for each pass. In effect, the object will experience a constant acceleration of 1 g, and you know that won't end well. After 1 hour the object's velocity will be about 35 km/sec, far greater than escape velocity, and its energy will be about 600 MJ. After a day, the energy of the object is about 358 GJ, which gives a velocity of about 846 km/sec. After a month, if you don't accept relativity the velocity of the object will be 248,000,000 m/sec, which is just a bit shy of the speed of light. There are some complications with this, most notably the rotation of the earth, which will tend to move the path of the falling body out of the portals, but this is clearly just a matter of engineering. Or, to a first approximation, you just put the portals at either the North or South Poles. [Answer] Your suggested method is not an alternative to FTL travel, it is a means of FTL travel. However you do it, if you reach one part of the universe from another faster than light could make the trip, you are indulging in Faster Than Light travel, and you will encounter problems with both Causality and Relativity. One of the best and most comprehensive explanations of FTL travel and the problems it raises with Causality and Relativity is hosted on [this page of Winchell Chung's excellent Atomic Rocket site](http://www.projectrho.com/public_html/rocket/fasterlight.php). This page also includes a comprehensive catalogue of FTL methods used in science fiction, known as The Canonical List of StarDrives or the Landis list, compiled by author [Geoffrey A. Landis](http://www.geoffreylandis.com). Your postulated method is included on the list as Portal-to-portal. [Answer] It's been used in science fiction a number of times, though I don't know off-hand of any rpg settings that use them. Some quick examples: Constellation Games by Leonard Richardson has an multi-species alien civilization visit Earth via just such a wormhole. They send a probe carrying one end of the wormhole at slower-than-light speeds, then send a group of explorers through. They have both one-way and two-way wormholes, and use one-way wormholes for exploration, because sending a million people to visit a primitive society is less disruptive than letting a trillion people have casual access. Edit: I almost forgot to mention it, but an interesting detail is that wormholes have a limited lifespan, measured in the amount of mass they can transfer. This means that a thriving multi-stellar civilization would need continuous production of new wormholes, and a continuous stream of ships carrying endpoints to where they are needed, in order to maintain consistent connectivity. That's the type of detail that would make for a lot of fun gameplay in an RPG. Glasshouse by Charles Stross has a human society living on the fringes of the solar system and in nearby stellar systems in immense habitats connected by wormholes. They're cheap enough that most people have apartments spread out over all of human space, with individual rooms connected by bi-directional wormholes. Although now that I think about it, Accelerando is really where the wormholes are mentioned more. Glasshouse is more about a group that splits itself off from the rest of the wormhole network after a war; the domestic uses are more clearly seen in Accelerando. A much earlier book that I recall, though I cannot recall the name, was about a society that used wormholes on Earth to connect up their homes and businesses. I believe the plot was mostly about a child who goes wandering around outside; the child's mother thinks he has a mental problem. Not a very interesting story, really. The Light of Other Days by Arthur C. Clarke (perhaps in collaboration with someone?) is quite interesting. Here the wormholes start out simply as a means of transmitting information between distant parts of the Earth without any time lag, making everyone's internet connections faster. Eventually they discover that the endpoints can be positioned outside of the equipment that generates it, and so the real story begins. They start out by placing the microscopic endpoint right in front of the eyes of a famous quarterback, to capture exactly what he was seeing when he made the big play, etc. At the end of the book they start using wormholes to scan people's minds just prior to their deaths, with the goal of bringing literally everyone who every lived back to life in reverse the order that they actually died. I recall another where the inventor of the wormhole was blackmailed, and sent his blackmailer to live for a time on another planet. I thought it was called Gone Fishing, but a quick search doesn't turn it up. Diaspora by Greg Egan has the descendants of humanity try to build a wormhole and fail. They spent 800 years setting up the experiment to create a wormhole (think of a particle accelerator like the LHC, but the size of the solar system), only to find out that although wormholes exist, they aren't actually shortcuts. All wormholes are as long on the inside as they are on the outside. This is a great book, superb on several levels, so I don't want to spoil it. They do ultimately discover a use for these long wormholes, and it's even more fantastic than short wormholes would have been. As others have mentioned, if your wormhole endpoints can dial up any other wormhole endpoint then you have Stargate, which is actually quite a fun show. You could have a lot of fun games in that kind of setting. As for plausibility, no, they're not plausible at all. The mathematics can "work" if you introduce some strange matter with negative mass, but that's precisely the sort of thing that the real laws of physics won't let you have. On the other hand, it would be hard to argue that wormholes are less plausible than FTL, so don't let that stop you. Your readers (or players) will suspend their disbelief of at least one thing in the setting. Oh yea, and Schlock Mercenary, mentioned in the comments above, is excellent. Very good world-building there, and good stories well told. [Answer] I’m not sure I fully understand your concept — I totally do not understand [your comments](https://worldbuilding.stackexchange.com/questions/41338/galactic-travel-an-alternative-to-ftl#comment117354_41344) on [WhatRoughBeast’s answer](https://worldbuilding.stackexchange.com/a/41344/20215) — but it sounds like you are talking about a technique that is also known as [“matter transmission,” a.k.a. teleportation](https://en.wikipedia.org/wiki/Matter_Transmission) — like the “teleporter” in Star Trek, but with a terminal at each end. Like wormholes, this is also [common in science fiction](https://en.wikipedia.org/wiki/Teleportation_in_fiction). In particular, I am reminded of [The Space Eater, by David Langford](http://ansible.uk/books/tse.html), in which humanity develops interstellar matter transmission (but not faster-than-light travel, per se), and then uses it to travel to another solar system, where they pretend that they got there via FTL (see [review/plot summary](http://www.hardsf.org/HSFRSpEa.htm)). [Answer] If you could somehow create a spacecraft capable of producing 1g acceleration constantly for multiple decades, you could travel to any place in the galaxy within one lifetime without ever exceeding the speed of light. And even some other galaxies are within reach. What saves you is time dilation. At 1g acceleration you will reach relativistic speeds after one year. As you keep accelerating at 1g the craft will appear to move closer and closer to the speed of light as seen by an outside observer, and time dilation will slow down the aging of the passengers. For the passengers on the craft the entire universe will appear to shrink in their direction of travel, which shortens the journey to an achievable distance. Once you are halfway there you'll have to start slowing down again. As a byproduct of accelerating at 1g the entire way, you get artificial gravity of 1g on your craft. There is a few caveats to this approach: * You better be sure you don't hit anything on the way to your destination. Even the tiniest object you may hit will hit you quite hard at close to the speed of light. * The rocket equation is problematic. You will need an extremely high exhaust velocity. * You could travel to the other side of the Milky Way and back again in a lifetime. But though the trip took you only a lifetime, the time on Earth will not have slowed down, and once you got back millennia would have passed. ]
[Question] [ So these magicians have been working on a new weapon for the King because he wants something to show off about. They were struggling for inspiration when they discovered a way of trapping the friction of the metal against the air inside an unobtanium steel alloy and releasing the trapped energy as heat. This heat trapping is so effective and so powerful that after a 15 minute charge time the sword can be heated to 1583 degrees celsius (2800 degrees fahrenheit). It can maintain this heat for a minute then it must have a 15 minute recharge during which time it is effectively a normal sword. The power of the sword has no direct effect on the wielder and also does not melt the sword. So to recap the powers are * Produces one minute of intense heat with 15 minute recharge. * Protects user from abilities of sword. * Protects user from other magical attacks. Given that the sword has these powers what issues for the user will the sword give? [Answer] Assuming, as mentioned in the question, that the user is protected from the effects of the sword, heat would not be an issue. As long as the user is holding the sword, he is protected from its heat. However, there are other issues. ## Time and Convenience If the sword heats up for only 1 minute, after 15 mins of recharging, then that's hardly efficient. That's a 15:1 ratio. Thus, seeing as a battle could last for several hours, the sword would then need at least a couple of days prior to the battle to charge. This would, of course, be an issue and a nuisance, because you may never know when the sword and its intense heat function may be needed, or for how long. With such an inefficient power output ratio, it may well be that the sword's intense heat function might rarely be used, if ever, simply because it just takes way too long to charge. ## Reliability How would the user know how much power is left in the sword, before it needs to be re-charged? It is possible that the user may come across a situation where the intense heat function is desperately needed, but activates it, only to find that there isn't enough power to heat the sword up for longer than a second. Some sort of timer should be incorporated into the sword to inform the user how much longer the sword can produce such heat. ## Safe-keeping The user may be protected from the heating effects of the sword, but not everything around him or it. The obvious housing for such a sword would be a scabbard, but then the scabbard would also have to be protected from the heat. This is so that the scabbard does not instantly explode in a cloud of ash if the sword is accidentally activated inside the scabbard. Especially because scabbards are usually made of wood, or leather. The scabbard could be made of the same material as the sword, of course, since the sword is not damaged by the heat, but that would make the scabbard very heavy. If, on the other hand, the material used to make the sword is light enough that the scabbard would not be a hindrance, then the sword itself would not have enough force when used, because it is too light. [Answer] Well, realistically, if the sword is giving off that kind of heat no one will be able to actually *use it* without risking tremendous harm to their own side. That thing would kill anyone who got within meters of it. It would bake knights in their armor - friends and foes alike. It would also start fires all around the user, which will be potentially deadly to the wielder (although the blade itself is not). If you're standing in the rain the super heated vapor might also harm you as puddles beneath your heat instantly boil. The only way to use this relatively safely would be outdoors, in a relatively moist environment, either by yourself, or far enough from your own forces that you won't harm them. However at that point you're putting yourself in a lot of danger on the battlefield. Unless this sword has a very specialized use (such as fighting a dragon one-on-one) it would not make a suitable weapon on the battlefield. [Answer] The melting point of stainless steel is [1363 degrees Celcius](http://ganoksin.com/blog/cgmfindings/2012/10/03/metal-melting-points-guide-to-melting-metals/) and molten steel is unpleasant to be around, but it's not going to kill everyone around it. Here's a guy standing next to a bunch of it: ![Guy not dying being next to molten steel](https://i.stack.imgur.com/KXxre.jpg) Just because an object is a certain temperature doesn't mean it instantly makes everything around it the same temperature. After all, the surface of the sun is [5498.85 degrees Celsius](https://en.wikipedia.org/wiki/Sun), but it's not that hot here on Earth. The filament in a light bulb can reach [2550 degrees Celsius](http://www.iar.unicamp.br/lab/luz/ld/L%E2mpadas/The%20Great%20Internet%20Light%20Bulb%20Book.pdf) but that's not how hot your room is (I hope). Probably the biggest issue that a user of this sword is going to face is just how bright the sword will be. It'd be quite distracting, and using it at night is going to leave the user and those around him fairly blind until the bright spots in their vision dissipate and their eyes adjust. Also, since the temperature is a couple hundred degrees hotter than the melting point of steel, there's a slight chance that if you try to stab an armored opponent with this sword while it's activated or slightly after it's turned off that it'll melt the edges of the armor you've pierced a little and then cool before you withdraw it resulting in a natural weld making it a little hard to pull your sword out. It probably wouldn't be a very clean weld or melt the armor very much, but it might take a good yank. "Whoever pulls my sword out of my enemy's corpse gets to be king for a day!" [Answer] There would be spontaneous combustion of nearby flammables, including papers, lacy curtains , clothing, and fancy hairdos. Nearby wax would slump and drip. Anyone standing nearby would be driven back by this intense heat. It would look quite impressive, if blinding, from a distance. [Answer] The heat from the sword will boil the moisture present in any nearby rocks, causing them to explode. Any moisture present in your surroundings will also boil, filling the air with clouds of scalding steam. The superheated steam-filled air would also rapidly expand and begin to race away from you, at least until the clouds of steam surrounding you reached an equilibrium temperature with the blade. Essentially, activating the sword would release a small pyroclastic flow full of shrapnel. This would kill anyone nearby, friend or foe. Do not activate at parties. [Answer] Well if the sword protects the user form it's self then I don't see many Issues with it. However the user has to have some way of activating the enchantment. Maybe by saying a particular phrase, word or spell. ]
[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/39232/edit). Closed 7 years ago. [Improve this question](/posts/39232/edit) I am a mad scientist who has discovered a way of efficiently killing all sorts of annoying flies, from mosquitoes to fruit flies, and want to unleash my creation upon the unsuspecting buzzers. However, I want to do it in a way such that I don't destroy the entire ecosystem by removing an important food source for birds, bats, frogs, etc. or replace any sort of other potentially useful properties of the flies (including preventing aliens from destroying the earth). How can I best accomplish this? [Answer] Three approaches. Approach One: slow and steady. Unleash your creation over the course of 100 million years. That will give the ecosystems enough time to adapt. After all, the best things in life are worth waiting for. Approach Two: apologetically. Kill off the flies in small area, and observe what ecosystems change. Say you're sorry to any birds or frogs you kill. Use your mad scientist skills to invent something which resolves those changes so it doesn't happen again. Then go to another small area and repeat. Remember to say you're sorry if you mess it up. Eventually you find that you can kill small areas off without any trouble. Now pick a larger area and repeat. If you mess up one of the larger areas, make sure everyone knows you're really sorry. Eventually you will develop an effective fly substitute (less calories, but tastes great!) which you can unleash alongside your creation. *Approach Three: \#&!@ it all** You don't want to unleash your fly killer without disrupting an ecosystem. Nuke the ecosystem from orbit. No ecosystem was destroyed by the removal of an important food source in this process. They were removed by fusion and/or fission! It's science, peoples! Then, once there are no more frogs or bats or birds to disrupt with your fly killer, feel free to unleash your creation without there being an ecosystem to disrupt (though it may not find many remaining flies to kill). After all, why be a mad scientist if you can't abuse a few measly loopholes! [Answer] Make a substitute to replace them - but you're going to have a hard time doing it. Flies as a whole are a huge group of insects, and killing them all would have a devastating effect on life on Earth. For starters, flies: 1. Are an important food source for many small animals - birds, frogs, reptiles, spiders, and many insects - which are themselves important food sources for larger carnivores 2. Play a huge part in quickly and efficiently getting rid of dead plants and animals before they can spread disease 3. Pollinate many kinds of plants which would die out without them If you want to get rid of all the flies without disrupting (or completely destroying) the ecosystem, you're going to have to first engineer a less annoying creature that can fill all those roles. Keep in mind that many species of flies are specialized for decomposing or pollinating specific species, so you'd have to come up with either an extreme generalist or millions of specialized neo-flies. You're much better off trying to figure out an effective way of repelling flies than trying to kill them all. Plus, then you could sell your invention to practically everyone and make a whole lot of money. [Answer] Here's how. 1- Take a common virus (any would do). 2- Genetically program the virus to attach to proteins found only in your target species body. 3- After invading the cell, the virus ought not make copies of itself (that's what all old fashioned viruses do) but instead changes some genes in the cell so that the cell starts producing botulinum. 4- Botulinum is the most lethal compound on Earth and would kill the target. The virus would die along with the target (it did not make copies of itself). 5- Prepare large amounts of your virus and spray it in the air. First in a few miles area and if you find that there are no adverse secondary effects of the elimination of the target species (remember, you make one different virus for every species), you keep increasing the spraying area. Until after a few years, you have tested that it is safe to eliminate certain species completely from the world. And then you spray the virus all over the world. ]
[Question] [ How could a planet which humans could land and survive on with no space suits or other help have a green atmosphere? The only requirement is that humans landing here would have to be able to breathe the atmosphere, and potentially live on the planet for their entire natural lives. Note - I would like to know the percentage of different gases for your answer. For example, if you replace 20% of the atmosphere (in H) and replace it with imagineum then your atmosphere would appear green. [Answer] I would guess it would be easier to change the sun the planet is revolving around. Blue light scatters the most and the colors go down from there. So if you have say a red dwarf, that is producing a lot less blue, then green is the next 'most scattered' color and with blue mostly missing, green should be prominent. Other other way would be to have something in the atmosphere that absorbs blue light. [Answer] There are two possible ways I know of why a planet's sky could be green. The planet has a super-abundant biosphere and the atmosphere is full of, what can be only called, aerophytoplankton. Tiny plant life that float in air the same way marine phytoplankton floats in the sea. The planet's crust has a high copper mineral content and the atmosphere is full of the dust of greenish copper minerals and compounds. This like the situation where the sky of the planet Mars looks reddish due to the colour of dust floating in its atmosphere. [Answer] A layer of Chlorine gas in the atmosphere would make it green, the problem with this is that it would also make it very dangerous for humans so you would need to separate the Chlorine and somehow keep it away from your observers. This could be done either by having isolated pockets Chlorine-free or by somehow restricting the Chlorine to a specific band in the atmosphere similar to our Ozone layer. [Answer] Even on Earth, there are times when the sky can appear green - generally before a storm. The exact reason for this is debatable, but it is probably related to the redness of sunset (itself caused by the sunlight passing through more atmosphere) combining with increased water droplets in the air. On a planet where such conditions were normal, the sky would always appear green to a human visitor. However, it would also be dimmer overall and all blues would be muted, since less blue light is getting through the atmosphere. And to a species adapted for seeing under these conditions, the sky would probably appear to be at the short-wavelength end of their visible spectrum. Transparent gases, as a rule, scatter more short-wavelength light than long-wavelength light, so unless you're blocking out light with colored gases, dust, or living organisms (all of which will make the surface appear dimmer) the sky will always appear blue. [Answer] There are humans which have colour blindness which makes them see colours differently. So theoretically, if a human has severe enough colour blindness, they may perceive our Earth skies as greenish. Humans can survive on this new world, which implies that other life could already exist there. If one of these alien organisms carried a virus (or something similar) which could infect the humans with non-lethal colour-blindness, then these humans would perceive the sky on this alien world as green. The virus could even be airborne, so they would catch it straight away after breathing the air and immediately start seeing green skies instead of blue. This would also mean the new planet could have similar atmospheric composition to our own, which would satisfy the condition that humans need to survive there unaided, while also having the atmosphere appear green. I know this isn't changing the atmosphere to be green, but colour is a matter of perception anyway ;) ]
[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/22692/edit). Closed 7 years ago. [Improve this question](/posts/22692/edit) Imagine this: All celestial bodies significantly smaller than a planet within our solar system (asteroids, debris etc.) are moved into an orbit around earth. The method of achieving this is not my concern. * Is this possible for comets? Will they 'survive' earth orbit? * What are the implications on earth? * What range to earth would be ideal for safety, minimal impact on earth and on the other hand small enough for convinient extraction / mining? * Do we need to limit the number of celestial bodies to avoid gravitational effects (floods an so on)? * Could this ever be stable, i.e. all bodies moving within stable curves? I know there is a somewhat [similar](https://worldbuilding.stackexchange.com/questions/12704/celestial-bodies-and-gravitational-effects-on-the-earth) question, but I find it different enough to ask this question. As always, thanks for your time! [Answer] This would be a big problem. The entire asteroid belt is approximately [4% the mass of the moon](http://www.sciencedaily.com/terms/asteroid_belt.htm) (this includes the dwarf planet Ceres). All the trojan asteroids add up to about [one-fifth of the mass of the asteroid belt](https://en.wikipedia.org/wiki/Jupiter_trojan#Numbers_and_mass). The Kuiper belt is next, its total mass is estimated to range between [1/25th and 1/10th the mass of the Earth](https://en.wikipedia.org/wiki/Kuiper_belt#Mass_and_size_distribution). So far, no problem. Then there is the Oort cloud. The Oort cloud is at the edges of our solar system and it is huge, literally astronomically huge. It also turns out it's fairly massive. The exact mass of the Oort cloud isn't known, but estimates put it [between four and eighty times the mass of the Earth](http://www.astronomynotes.com/solfluf/s8.htm). Anyone who adds eighty Earth's worth of mass into orbit around the Earth is not going to have a good time. There is a perspective shift here, and it might make more sense to say the Earth is orbiting the debris. A lot of the effects are going to depend on the balancing of that mass in orbit around the Earth, needless to say, it's not going to be a simple task. Such a thing could be stable, but only for a short period of time, it's far too much mass to keep track of and maintain. It's also far more material than could conceivably be needed for mining, but we passed that threshold when we brought the entire asteroid belt (with a dwarf planet) in for mining. [Answer] Basically, everybody dies Moving that many bodies into near earth orbit is going to have serious implications because none of those orbits are stable and collisions will be frequent and spectacular. For a visualization of this process of decaying orbits, check out this [video](https://youtu.be/Kv1zZaO__8A) made in Universe Sandbox 2. Something is going to hit earth and chances are, it will be big. Anything with orbital velocity above 10km in size is going to be a huge huge problem. Maybe not enough to boil the oceans but definitely an extinction level event. ![Burning Moons are terrifying cool! ](https://i.stack.imgur.com/LoUnh.jpg) ]
[Question] [ If while exploring the galaxy, we were to encounter an alien script, would we be able to decipher the pronunciation of the language without actually hearing it? Assumptions: * The language is pronounceable by human tongue * The text found is very large, equivalent to several long novels * The text describes many aspects of culture and history, and includes many names and possibly even descriptions of how they are pronounced (in the alien language of course) * The language follows a writing system that works similarly to an alphabet, with individual letters combining to form syllables which combine to form words * Advanced tech level, so computational power isn't an issue * The world's linguists are, for obvious reasons, supremely interested in this task Challenges: * I've heard references before that this isn't possible but I can't locate them * Would names be harder to figure out than words, assuming the names are not based on actual words to begin with? Would we actually be able to figure it out, at least somewhat closely to the original? Or would any ideas we came up with be purely guesswork? [Answer] Please encode for Maximum Meaning With modern day compute power, a xenolinguist would be able to find many many things of interest in this alien script such as the distribution and grouping of letters or ideograms, common words, common clustering of words, numbering system, even the writing style of various authors. With a math text, we might even be able to learn how they encode math. However, stats only gets us so far. Mapping one alien symbol into modern English requires recovering an idea from the mind of an alien. The math text would perhaps be the closest thing to a [Rosetta Stone](https://en.wikipedia.org/wiki/Rosetta_Stone) that we get. Remember that the Rosetta Stone provided the critical piece that allowed modern linguistics to finally translate Egyptian hieroglyphics into a modern language by way of ancient Greek. Prior to its discovery, Egyptian was completely unreadable. Essentially, these very long texts are random strings of numbers. One can find patterns in those numbers and relationships within the document itself but without some way of mapping a number or number cluster in that long string into a real life concept then translation and pronunciation is impossible. All Tongue tied But let's try anyway. Pronunciation won't be possible with any kind of fidelity without talking to an alien or some kind of wicked clever inference from an artifact. One possible approach exploits how poetry is written to derive pronunciation. Take Middle English poetry. The speakers of that language are long long dead and their tongues with them. There are no recordings to listen to so inferences must be made through textual analysis, specifically which words rhyme together in a poem. Linguistics exploit their knowledge of how poetry works in English. However, this would not work for analysis of Hebrew poetry because they don't worry about clever things with the sounds of words but rather clever arrangements of meanings (or double or triple meanings) between lines. Isaiah is an excellent example of this kind of poet though you'll need a strong background in Hebrew to really appreciate it. We don't even know if they spoke their language. What if they used scents or bioluminescence to signal with each other? There is no sound to pronounce! Translation is near impossible. Pronunciation without a "form your mouth like this" guide will be equally impossible. [Answer] Our ability to translate the language will greatly hinge on context. From your question, it seems you are describing a singular text. Possibly a collection of news articles or even a "welcome to the planet" type guide. If we were to find this isolated from anything indicating its origin and purpose, we would have almost no hope of translating it. (An infinitely powerful computer would be able to generate many possible translations. It may even be able to calculate the most likely one, but we could never be sure.) If, however, this was not a singular text, but rather the sum of text found about the ruins of a city, we could certainly translate at least most of it. With such a context, we will begin to see patterns such as enter/exit, open/closed, left/right, etc. (I can't find it now, but I saw a documentary once in which the key that allowed us to to translate an ancient text was noticing a pattern where two words were repeated. Someone hypothesized they were "born" and "died" and they were able to crack the rest of it from there. But would she have made that guess if this text hadn't been discovered with a burial ground, as it was?) Hypothetically, you could contrive a situation where enough context existed to translate a singular isolated text. Numbers are easily translated if enough are present (math being the only known universal language), and if there were corresponding explanations accompanying the numerical notations, this could be enough to crack the code. Getting a bit more out there, if we suspected the text was written by a race we had never encountered but had heard much about, we might come across a translation by trying to make it fit what we know. Or perhaps the material it's written on or the location it was found lead us to believe the text is a specific one we've heard of (e. g. The Holy Book Of Mak'Ra) and we translate it by already having a rough idea what it says. Any pronunciation will be guess. [We don't even know how Latin was pronounced in ancient times](https://en.wikipedia.org/wiki/Latin_pronunciation), and we have a lot of information to go on. We are still speaking several languages derived from it. This helps us to guess at the pronunciation, but there is still much uncertainty involved. In your scenario, we don't have any such clues. Assuming we translate it, the most accurate we could hope to be in pronouncing the language would be knowing which letters are consonants and which are vowels. Any written pronunciation guide will rely on us already knowing how to pronounce the words or symbols used as reference, which we can't possibly know. Imagine a Japanese speaker learning English solely by learning the translation of each English word he reads. He can now read English fluently but has no knowledge of pronunciation, so he gets a copy of Webster's Dictionary. Even though he understands everything he reads, he won't know how the phonetic spellings are supposed to sound, and will be no closer to knowing English pronunciation. This is the situation we will find ourselves in. [Answer] Maybe. It depends both on the writing system and on how much material you have — both written material, and additional clues regarding the sounds used by the language. One thing you'll need is some indication of what sounds a language can use. With humans, we know this. But with aliens, we would need additional information. This could be recordings of speech (even if we have no correspondence between these recordings and the writing, they would be enough to determine the phonemes of the language). This could be remains or an anatomical text with diagrams. It could be a treatise on pronunciation (once the meaning of the text can be understood). Some information on morphology and psychology can also hint at the pronunciation of a few words, such as onomatopoeia. For example, many unrelated human languages have a word for “mother” that sounds like [ma], which is an easy sound for babies to make. Languages vary greatly in how difficult it is to relate the writing to phonemes. At one extreme, there's pure ideograms, where the writing is unrelated to pronunciation. At another extreme, there are languages where each mark represents a sound. Among humans, pronunciation and writing tend to evolve independently, so even languages where the writing system was designed to be purely phonetic have usually diverged after a few centuries. English is on the far side of divergence, with spelling only loosely connected to pronunciation, and strong phonemic variation between variants. At another extreme, there's [Korean](https://en.wikipedia.org/wiki/Korean_language), whose [writing system (Hangul)](https://en.wikipedia.org/wiki/Hangul) (a syllabary) is systematically constructed out of building blocks where the mark representing a phoneme is a stylized representation of the shape of the mouth when pronouncing that phoneme. If the writing system is designed like the one of English, you won't be able to know how it's pronounced with any certainty since even native speakers vary, your only recourse would be to find a treatise on pronunciation. On the other hand, if the writing system is like Hangul, then you might have a chance to guess at least the original pronunciation (not necessarily the modern pronunciation if it's evolved since the writing system was designed). The nature of the texts matter as well. If there's any ambiguity in the relation between spelling and pronunciation, our main clue for the pronunciation of human languages is rhymes. Rhyming poetry, theater and songs are how we reconstruct the pronunciations of centuries past. A book on puns would also be helpful. A history treatise, markedly less so — though it might include pronunciation clues for old or foreign names. Your explorers should definitely be on the lookout for multiple languages. Deciphering multiple languages with etymological connections can provide information about the individual languages. For example, if a language imported words from another, the way those words are modified can provide clues about the sounds of both languages. Of course multilingual texts like the Rosetta Stone can be very helpful. Even better, they might find language textbooks. [Answer] It is only possible if (a) there is a sound-based key (a recording of some type), or (b) a detailed anatomical description of the alien's 'mouth' and its operation. For example it is possible to get some idea of how a Roman musical instrument would sound by looking at an old picture or an archaeological find. This is because we have an idea of the physical appearance of the instrument and the fact that it has strings or there is someone blowing through it. On a slightly different tack but still connected: See just how difficult it would be even to understand it without a key, have a look at this <https://en.wikipedia.org/wiki/Code_talker> [Answer] Given that a spoken language uses a specific collection of sounds, specific letter representations of sounds are essentially arbitrary. Even assuming the text is perfectly phonetic, as English is not, there is simply no way to determine which phonemes go with which letters. So, without an audio recording which corresponds with a specific (and specified) text, pronunciation is unknowable. [Answer] I mostly agree with the assessment that it will be impossible. However, there might be one slender ray of hope ... Mistakes, Homophones, and Texting Abbreviations With really good statistical analysis, you might find out that a "two" in a certain text [should have been](https://en.wikipedia.org/wiki/Homophone) a "too" instead. Of course first you'd have to be certain that "two" doesn't mean "too", and that it isn't just a typing error. That tells you "two" and "too" have very similar pronounciations. Then you come across [4u](https://en.wikipedia.org/wiki/SMS_language#A_single_letter_or_digit_can_replace_a_syllable_or_phoneme) in a text and figure out that four, 4, and for sound similar. Still, that only helps to divide words into [equivalence classes](https://en.wikipedia.org/wiki/Equivalence_class). You have no idea how each is pronounced. Onomatopoeia A few words in most languages try to [imitate the sound they describe](https://en.wikipedia.org/wiki/Onomatopoeia). If you find such a word, and become reasonably sure that it is onomatopoetic, that might be the rosetta stone to unravel the rest. If there really are alien ruins with alien script, and if there are enough linguists working on it, expect some papers suggesting pronounciation. Some might even be right. After a century of academic infighting, they might settle on a "consensus theory" ... [Answer] This is unlikely in the extreme. Humans could not decipher the ancient Egyptian language until the discovery of the Rosetta Stone (which had the same texts in Egyptian and Ancient Greek), and we still have no clue about deciphering "Linear A"; the script of the ancient Minoans. There are other languages which are not clearly translated either; ancient Sanskrit is thought to be full of hidden meanings which we don't understand because the ancient peoples who wrote in this language seem to have been fond of word games and puns; which don't translate well, if at all. Since alien beings will have alien concepts, there will be very little context to even begin translation. Perhaps the only thing that will be translatable is mathematics (and even then some of the concepts might be very difficult to translate). So there may be some elements that can be translated, but most of what will be seen will be a mixture of conjecture and guesswork. ]
[Question] [ ### Scenario I'm trying to design a colony spaceship. My main character, a soldier, awakes prematurely from suspended animation (SA) to find that the colony ship she is on, headed for [Tau Ceti e](http://en.wikipedia.org/wiki/Tau_Ceti_e), is in a mutiny. The journey was supposed to last about 14 years, but she's awoken halfway through the journey. There are 26,000 people total on the ship, of which there are about 400 trained soldiers, and 5,000 children. Originally, I had almost everyone in suspended animation before the mutiny. The mutineers had pre-planned coming out of SA early and "taking over" the ship. However, as I thought about it, this wouldn't make sense with some plot points that I'd like to remain in place: * The mutiny must take place between years 4 and 10 of the journey. This period constitutes a communication "dead zone". Any sooner or any later, and the ship can send a distress signal to either Earth or the existing colonies on Tau Ceti e, which can then remotely control the ship and suppress the mutiny. * The destination remains Tau Ceti e. * The main character must be in SA, because of reasons, and come out of it when the mutiny starts (okay, I suppose it's not necessary that she be in SA, but it's important to note that SA exists in this world). * SA works by replacing the person's blood with a saline solution, and essentially freezing the body until it's time to come out of it, at which point the blood is returned, the body warmed up, and the heart shocked into beating again. Basically, cryonics. [See this answer to a related question.](https://worldbuilding.stackexchange.com/a/14422/7312) + Normal brain function is retained by way of science + Some physical/mental recovery after SA is necessary, usually a week. + The space requirements per person in SA is 275 cu. ft. + Once out of SA, you can only go back in by the help of 2 highly trained technicians. * Presumably, the mutineers would still want most people to survive the rest of journey. Perhaps not the soldiers, though. If everyone were in suspended animation, then the mutineers couldn't survive the rest of the journey after their planned mutiny. There wouldn't be enough food, water, life support, etc., to sustain them. Even if it was just one person coming out for the mutiny, there is probably no way that this person could live for the rest of the trip. Perhaps one or two mutineers could survive, assuming there would already be a small group of technicians awake. But there are problems with this too, not the least of which is that this doesn't make for an interesting story. So I'm designing a ship where everyone is awake and alive for the 14 year trip. All necessary considerations would be in place: artificial gravity, food sources, water recycling, life support, recreation, education, social structures, etc. ### Question I'm having trouble reconciling the fact that suspended animation exists in this context, but they aren't putting everyone in it for the duration of the journey. It seems like it would be way too expensive, and just a lot of trouble, to design and operate a ship where everyone is conscious; after all, they could just basically kill everyone and revive them later. What are the costs, maybe in terms of energy, of having everyone awake and alive, vs the costs of putting everyone in suspended animation? In the case that it's much cheaper and easier to use SA (which is what I'm expecting), why would they not use suspended animation for the journey? Edit One advantage that I thought of for everyone being awake...the ship could be designed to gradually acclimate the colonists to the environmental conditions of their new home. This couldn't happen if everyone were in SA. I don't know the details of that environment yet, except that acceleration due to gravity would be about $1.4\ g$. Atmospheric pressure would be higher, but I'm not sure yet by how much. I'm also not sure how much benefit this would provide; I may ask another question about acclimating to a different gravity/pressure. [Answer] If suspended animation is a plausible tech, it would absolutely be used for practically everyone. The biological needs of 26 thousand people for 14 years would be massive - oxygen, food, water, CO2 scrubbing, heat dissipation, etc. A recycling system/biome would certainly help, but the more people it has to support, the bigger and more complex it needs to be. Providing for 26k people for 14 years is a massive incentive to keep as many people frozen as possible. One way around your problem is to limit the safety of long-term suspended animation. If it is not safe to remain in a suspended state for the entire journey, people may need to be awoken on a rotating basis. If cellular degradation becomes a concern if frozen long-term (no processes working to heal radiation damage in a dormant body), necessitating a couple of weeks for medical evaluation and period of healing every 8 to 10 years of suspension, everyone will need to have a recuperation period mid-trip. This should not likely be something fatal, but increasing the possibility of harm the longer they are under (risk of mild brain damage, personality shifts, memory loss, etc - the physical damage can heal but those memories are gone). Aside from a small crew who remain awake to service the vessel and maintain the systems, perhaps only a few hundred people are awake at any given moment? During the middle third of the trip, passengers are being woken up, have a 2 week checkout and recovery period, then refrozen. Those planning the mutiny arrange to all be part of the same group, thus they can overwhelm everyone else and take control. Safety margins for life support should allow a few hundred extra people up and around (though maybe slightly degrade systems long-term as it is pushed a bit). They are not killing the other passengers by shrinking the number being cycled through health checks, just increasing the risk of damage by exceeding safety protocols (hopefully no non-recoverable injury will occur, and if some unfortunately does happen, just acceptable collateral damage for the cause). This puts the mutineers able to take over, and your protagonist is part of the next cycle of passengers (albeit of reduced numbers). Suspended animation limits like this may not fit your plot (not sure what the mutineers expect to accomplish), but gives you mid-trip timing and a protagonist waking up in the middle of it, as well as addressing why the ship would have supplies to keep extra people up and awake. [Answer] I think you can stick with your original plan with a slight modification. The key is to consider what needs to happen at the end of the journey. Official Plan: All colonists asleep. Most soldiers/security asleep (probably 1-2 awake). 10-12 technicians awake at any time, working in 1-year shifts with overlap. At the end of the journey, the colonists must be woken up in large groups on the ship, allowed to recover, and then shipped down to the planet. This requires a temporary boost in the ship's life support - probably something that couldn't normally be sustained for the full trip, but could be used for a couple of months to get the colonists down. Mutineer's Plan: The mutineers will make use of that temporary boost in life support. Instead of using it to support thousands of people for a 1-2 months, they'll ration it out so that it can support the 100-200 mutineers for the remaining duration of the trip. Once they arrive at their destination, they will replenish the life support from Tau Ceti, letting them eventually get the colonists out of SA and down to the planet. This will delay the colonists getting to the planet, but gets them their alive so the mutineers consider it acceptable. [Answer] The human body uses less energy when it's asleep than when awake: slower breathing, slower heart rate, reduced brain function, etc. If there's no one around, you don't need to leave the lights on or provide power to food/water storage. So using SA is, in terms of energy consumption, far more efficient than having everyone banging their head against the walls for a dozen years. Why wouldn't they use SA? Simple: precautionary measures to prevent mutinies (and avoid other scenarios) dictate at least X% of crew must be awake at any given time. They'd keep a specialist or two on hand, enough soldiers to hold off a small boarding party/group of mutineers, and crew sufficient to ensure the ship continues to run smoothly. While machines could do this, there's been a persistent desire for a human to be in control and perform routine visual inspections. This protection only concerns the crew and guards on board. Civilian colonists wouldn't need to be awake for the entire duration unless they were utterly opposed to the idea being held in SA. (You can be certain there will be some like this.) [Answer] Arguably the most plausible scenario is that the colonists destined for the planet are kept in SA, while a small crew stays awake for the journey to run the ship. This way you keep your life support requirements low (only enough for the e.g. 15 technicians, don't need anything more than the SA gear for the 26,000 colonists), don't need near as much food, etc. Depending on how your SA bays work, they may not even need to remain pressurized during the journey, which further reduces the costs of keeping your small crew functional during the journey. To execute a mutiny, then, they'd just need an insider or two on the awake crew, and some way to reach and wake the others. On a quiet 14-year journey, it would be no problem for even just one mutineer to sneak off on occasion and wake up another 2 or 3 people (of course sabotaging the monitoring gear so as to prevent anyone else noticing what's going on) or bring them some food and supplies. Then they'd start by isolating the "loyalists" one or a few at a time, neutralizing them (maybe they kill them, maybe they just stuff them into the recently-vacated SA pods, or maybe they just tie 'em up in a corner -- up to you, really), until only the mutineers are awake and thus de facto in control of the ship. Even if in communications range of either end of the journey, no one outside the ship would have any idea what's going on. Unfortunately (for the mutineers), in tampering with the SA monitors, they accidentally woke up one of the soldiers, who now has to figure out what's going on (while trying to shake off the after-effects of SA) and then deal with the problem somehow... [Answer] Energy requirements in suspended animation This depends on how SA works in your world. If you just cool people down and swap out their blood with saline, energy requirements will be very low. One of the main resources that's common in space is cold, so you won;t have to run expensive cooling equipment to maintain a state of cryostatis for your colonists. It's likely, though, that you'll want to replace their blood with something more complex than saline for a long trip like this, probably something with the ability to sustain the cells (their metabolic rate is very low, but not zero) and prevent decomposition (bacterial metabolic rates are similarly low, but also not zero). This substance may be expensive, but it only needs to be injected into a person at the start of the journey. Of course, that's assuming that the suspension fluid lasts for the whole journey. If suspended animation is possible, but the fluid used to do so needs to be replaced every day, you're looking at 5 liters of fluid per day per person. If this is also something that can't be produced mid-flight (perhaps it requires a huge lab and lots of energy), the volume and mass of the suspended animation fluid required to keep the whole ship hibernating for 14 years may be more than the cost of just feeding them. Energy requirements for a regular person Roughly: 2000 kCal/day. Water and air can be recycled indefinitely, but energy from food will be burned for live humans in the form of irrecoverable heat. Even if carbon etc. can be recovered and re-formed into food via an internal ecosystem with plants and whatnot, fusion energy is going to be required to grow all of the plants. Furthermore, all of the water, air, and food recycling infrastructure takes up space and has mass. The more mass you space craft needs to transport, the more energy it will require to move. Even if it's something like a solar sail, a bigger sail will be needed to move a heavier ship, which will cost more. So which costs more? Up to you! You can definitely come up with plausible reasons for suspending someone to take more energy or for leaving them up and running to take more energy. For your story, it probably makes more sense to assume that lots of resources are needed to keep someone in suspended animation. So why use SA for some people? One of the key uses for SA proposed in the modern world is for medicine. People in suspended animation won't die due to blood loss or massive organ failure. Maybe, as part of the mutineer's plot, most of the security guards got baked with radiation while leaving the solar system. The hero of our story survived, but the damage was so extensive that he had to be put under SA for months while nanobots repaired damage at a cellular level. The mutineers, after all, don't need everyone in suspended animation, just the people who would stop the mutiny. They could trigger some sort of medical emergency, wait for the guards to get put in SA, and then strike. Unbeknownst to the mutineers, one soldier evaded the worst of the damage and wakes up early. Is he early enough to stop them? Find out by reading The Early Riser. [Answer] I don't think you need to wake all your mutineers up for this Think about it - you don't need the ship to go somewhere else. You don't need the people to do anything they weren't already doing. All you're trying to change is the circumstances when you arrive. (Borrowing some aspects from Dan's plan above) So your constraints are: * you need to maintain radio silence after the mutiny (or at least prevent any distress calls) * you can't increase the number of awake crew for any substantial amount of time (due to life support) * someone on the boat has to be awake as a setup. (Preferably a guard, but let's assume it's a sympathetic tech.) * Your slave crew has the skills needed to run the ship (since your life-support budget can't afford the extra security) The (admittedly harsh) plan: 1. Tech wakes up the "prize crew". 2. If this can be done without alarms, flush the tubes of the sleeping guards. (Removes possibility of them being awoken later). If this can't be done without alarms, do this after you've secured the ship. 3. Kill out the alive guards as quietly as possible. (And you're in space, so you have options up-to-and-including just venting atmosphere in their compartments) 4. Freeze (or space; their choice) the current techs on duty (if the ship can be controlled remotely, you can't afford someone being a hero and hitting the panic button down the road). 5. Optional: find whatever mechanism allows remote-command of your ship and disable it (may not be an option in your world) At this point, the only people awake are your people, your casualties are the guards plus any tech who didn't want to go into SA, and so long as the authorities planet-side aren't tipped off, you're good to go. ]
[Question] [ Let's say that tens of thousands of years pass and earth effectively becomes a giant city. What species of organisms survive our conquest? How do these species evolve to adapt? How long would human progress have to stagnate for any organism to become a competitor or threat? [Answer] You can extend what is already happening in our cities today. Cities generally do still have fairly extensive green areas, with paved areas and houses between them. Inner cities obviously are harder to survive in but even there you have lots of discarded human food to live of. You should expect to see a lot of scavengers. The animals that already adapt well such as foxes, rats, seagulls and other birds. Large grazers or carnivores clearly would not do well. Small animals like squirrels and other rodents would generally do fine and you might well find isolated populations developing in different areas. For example a specific breed of squirrel might evolve in one park, distinct from another park because there is no easy way to cross between them. Cockroaches and other similar scavenging insects may also succeed, although we may well have developed efficient ways to wipe them out and as a result they are consigned to zoos. [Answer] You are thinking about something like [Trantor](http://en.wikipedia.org/wiki/Trantor). It is extremely unlikely something like this to happen. Reason is a simple energy balance. You have to feed your population, and provide it with energy. For that you need fields: area where you produce food, open to sun. That is area where all kinds of animals can live. Most of such land is marginal, and will not be used for agriculture. And even more area will need to be devoted to producing carbon-neutral energy. Without carbon-neutral energy, your climate will collapse and productivity of your field will collapse, and your population will starve. To increase population density, you will have to import food from dozens of other planets, and those planets have to be also habitable to be able to export food. What would Earth export in return? And where the energy to lift Earth's export will come from? And if humanity has access to such huge reserves of energy and many habitable planets, why not to move there? Trantor was a center for huge fictional galactic empire based on Roman Empire, with many worlds devoted to farming, and with no robots to do the farming and other tedious work. I think that your ability to supply carbon-neutral energy for your over-populated will run out sooner than area for farming and wild places like mountains. Humans do not have to stagnate - they need to "get to the stars". Plenty of space in Space. Some more thinking... I think OP ever-estimates plausibility of future overpopulation. Even today, person in technologically advanced society needs half year of education (with no income) for every year of work for income - elementary school to graduate degree. In the future, time invested in education to gain skills necessary for paid work will increase, and need for low-skilled work is steadily decreasing. Such pressure has same effect in all developed societies: decrease of female fecundity. USA is exception, not a rule: most other advanced societies have decreasing population, and not increasing. [r/K selection theory](http://en.wikipedia.org/wiki/R/K_selection_theory) distinguishes between two population strategies: * r strategy: produce as many offsprings as possible, and spend little resources supporting them * K strategy: have few descendants, but spend lots of resources to make sure they succeed I claim that K strategy is better suited for technological future of humanity. In the future, maybe even right to have a child will have to be earned (because r strategist cannot expect responsible taxpayers to support his or her r strategy, while limiting own strategy to K because of limited resources). Humanity will have to face limited resources, and adjust morality accordingly. Will it be forced sterilization after second child for a woman on welfare? Effective contraceptives in public drinking water? If every child has right to be loved and has access to opportunities, it forces K strategy on humanity. [Answer] Plenty of species already evolve with us in urban environments (at least 'evolve' in the sense that they thrive and benefit from the urban environment). * pigeons * hawks * rats * mice * squirrels * raccoons * feral cats, dogs * domestic pets * even bears, moose (when in proximity to urban areas) Species that are adept at changing environments and opportunistic in terms of leveraging human environments will thrive. Others will not. While not urban-centric, the PBS documentary on Dogs talks about one particular species that has thrived with humans: <http://www.pbs.org/wnet/nature/dogs-that-changed-the-world-introduction/1273/> [Answer] > > Let's say that tens of thousands of years pass and earth effectively becomes a giant city. > > > Ok. Given a compelling enough economic rationale, it's doable. Even without doing a single calculation, you can already know you'd have to replace all cultivated fields with massive hydroponic food factories, so you'd still have vast amounts of the city (say a few levels) dedicated to agriculture. You'd have to modularize the city to make it resistant to earthquakes, and you'd have to capture and channel much of the waterflow that currently flows in rivers. None of this would be cheap. The question is whether there's a compelling reason to have that many people close together. A dense city like Mumbai or New York will usually top out at something like 30,000 people per sq. km. With proper technology, you can easily double that, perhaps even expand tenfold. But for comparison's sake, let's stick to Mumbai levels of today. With a land surface area of 149,000,000 sq. km, and given a 60% utilization rate (avoiding tall mountains and frozen tundras) you get a population of 2,682,000,000,000. That is about 2.7 trillion which is about 400 times more people than you have on the planet today. The energy production levels needed to support such a population, even with advanced hydroponics, are currently beyond our technology. Perhaps with massive space-based agro-habitats and solar plants linked to the Earth by space elevators, or with a multi-level arcology of which a non-trivial portion is reserved for agricultural purposes. > > What species of organisms survive our conquest? How do these species evolve to adapt? > > > With 100% certainty, vast numbers of single-celled organism species, such as bacteria yeasts, molds. With almost 100% certainty, cockroaches, ants and mites. With >95% certainty, mice, rats, cats, dogs. With >90% certainty: pigeons, sparrows and other climate-equivalents. > > How long would human progress have to stagnate for any organism to become a competitor or threat? > > > Unlikely to ever happen. By colonizing the entire planet, we will likely drive into extinction or zoos all other large mammals that could possibly compete against us. With 2.7 trillion people, you'd be in no risk of being numerically overwhelmed anytime soon. The only threats to such a megalopolis would be internal strife upsetting the complex networks required to keep each portion of it alive and thriving. ]
[Question] [ I'm wondering what types of firearms would be impacted if explosives and combustion in general were to have a random chance of being more potent or less potent. Could new firearms and/or ammunition be feasibly designed to adjust for this random variability? More specifically, the setting/world I'm working on has electricity and the associated tech disrupted instantly, while the combustion effect discribed slowly builds over about 10years time. At first the combustion effect has a low intensity and a low chance of occurring distributed in a bell curve favoring normalcy, but over time the chance and intensity of the effect increase with up to 90% burn variability evenly distributed. Assuming that technology level at the start of the 10 years is identical or higher than our own world, which types of firearms,explosives and other combustion dependent weapons would break down first? The effect impacts everything and anything that is capable of burning or exploding, not just things that were made after the effect started, although slower burning combustibles (Wood for example) are impacted to a lesser degree. The effect is global, and stays the same for a few seconds at a time before randomizing again. The effect impacts living entities considerably less than inanimate objects(to the point that life is not directly disrupted by the effects in any noticeable way). It is also localized as much as possible to just explosion pressure and electricity. [Answer] A firearm is - at it's core - a very simple device. In the most simple form it is just a cylinder closed at the bottom. You fill it with explosive, put a projectile on top, ignite the explosive and the expanding gas pushes the projectile forward. This basic principle hasn't changed much in the past 1000 years. When you don't know how powerful the explosive is, you won't know how fast the projectile will be when it exits the barrel, so shooting at a target far away will be quite a game of chance as you don't know if your bullet will fly far enough. You also need to make sure that the barrel is stable enough to withstand the explosion even in the worst case that the explosive is as strong as it could be. When muskets and cannons started to appear on the battlefields of the late middle ages, this problem was a very real one. Gunpowder could be weaker or stronger depending on how dry it was stored, the quality of the ingredients which were available to make it and how accurately they were mixed. Also, the operators weren't accurately measuring the amount of gunpowder to pour into their guns. So guns had to be designed to deal with this. With the invention of half- and full-automatic firearms, the exact explosive power matters more, since they also use its power to drive the mechanics which load the next cartridge into the chamber. Not enough power, and it might not work and the gun jams. Too much power, and the mechanic might be damaged. The comfort zone between these two limits varies from model to model. Modern production methods for gunpowder made the quality of ammunition much more consistent, which is a prerequisite for making such weapons work reliably. When you want your modern firearm to be really reliable even when your ammunition isn't, you better get a lever-operated or pump-action gun. They are usually designed in a way that even in case that the cartridge is a dud, the normal repetition procedure will eject it and replace it with the next one. When you still want full-auto fire, you could drive the reloading mechanics with another power source. [There are larger automatic weapons which use a motor to drive the cycling mechanic](https://en.wikipedia.org/wiki/Chain_gun), but without electric motors or combustion motors, the only remaining option would be a hand crank, like [the original gatling gun](https://en.wikipedia.org/wiki/Gatling_gun). Another option would be to refrain from the explosive and pick another acceleration method. There are several options available which already exist: * Electromagnetism, giving you a [railgun](https://en.wikipedia.org/wiki/Railgun) or [coilgun](https://en.wikipedia.org/wiki/Coilgun). Prototypes exist, but they currently lack a use-case. Their main disadvantage is that they require huge amounts of electricity, so when you want them to be strong enough to be lethal, they will likely not be man-portable anymore. You said that electricity works even worse in your world than combustion, so this is likely not an option for you. * You can use compressed gas to accelerate your projectile, giving you an [air gun](https://en.wikipedia.org/wiki/Air_gun). There are many of these commercially available today, but most of them are designed as non-lethal toys or sports equipment, which means they are usually designed for minimum lethality. However, with higher gas pressure and more lethally designed projectiles, the technology could easily be adapted for creating lethal weapons. * Mechanical energy stored by deforming elastic materials, giving you a bow, crossbow or slingshot - a family of weapons which has proven to be deadly and reliable for thousands of years. After the collapse of an advanced civilization these might again become popular, because these weapons and their ammunition can be made from readily available materials with no tools more sophisticated than a knife. [Answer] Sounds like you are building on Stirling's Change/Emberverse series and Boyett's Ariel. Great reads if you haven't already encountered them. The challenge with such anti-combustion ideas however is that they change the observable symptoms (fire and explosions) rather than the underlying causes of that combustion (oxidation). I'm not very current on the chemistry involved, but three decades ago when chemistry textbooks littered my dorm room floor, fire was taught to be an chain of exothermic reactions in which oxygen was added to an existing molecule's structure, yeilding enough energy to more than fuel the start of that same reaction in adjacent molecues. Things burn slowly when the yeilded energy is just enough to set off a few chain reactions. Things explode when the earliest reactions yeilds enough energy to simultaneously set off chain reactions in all surrounding molecules. Unfortunatley the oxidation reaction is common outside of open combustion including many biological processes which are needed to keep us alive. So if some foreign entity somehow changed the physical laws of the universe to globally change how oxidation functions, none of us would be here to see if the guns still work. It cannot therefore be a change to the burning process, it has to be a change in the fuel. So some entity selectively changes the strength of specific atomic bonds, making them stonger so that in molecules containing these bonds, the oxidation reaction chaining barely functions or doesn't function at all. That seems reasonable until you realize that the strength of those atomic bonds is important to other processes besides oxidation. Again the fragile structures of life fall apart and there is no one left to check if the guns work. Sadly, it doesn't look like we would survive any physical law modifications which might result in a change in the combustability of gun powder. From a world building point of view, changing the way combustion works is a tool for pushing your modern-day born characters into an age before Samuel Colt made all men equal. If you really want to stay reality based, you might be better served by an oil eating virus to destroy the economy and the ammunition assembly lines, followed by a global civil war to use up all the existing ammo. The removal of firearms from a modern day apocolyptic has been used as the premise for some really great science-fantasy adventure stories. The fact that none of them could pass a reality check didn't make them any less fun to read. So I say ignore the science and write it anyway. [Answer] The whole idea of affecting combustion intensity and electricity to reduce us to the middle ages has serious drawbacks. Our bodies are essentially electrochemical thermodynamic engines. Tweak the laws of physics too far and we die. Or our biology is so impacted that: 1. we become idiots or vegetables 2. we become crippled 3. we can't reproduce The same quantum physical qualities of metal that give it good electrical conductivity also give it good thermal conductivity, ductility, toughness, and reflectivity. With electrical conductivity eliminated the other qualities will also go. No shiny armor and swords, no frying pans, mirrors, pretty silver chalices, or gold jewelry. Instead of a romantic Tolkienesque world you will have cavemen with sticks and stones. The whole issue of combustion reduction revolves around one issue: catalysts! The right catalyst can accelerate chemical reactions. Also the types of chemicals used and the fineness of the particles will define the reaction rate. Also there are two types of explosion. Gunpowder just burns fast. Nitroglycerin actually decomposes at a rate faster than the speed of sound releasing chemical energy. Big difference. Look it up. Compressibility gas laws and thermodynamics don't just affect machines. They affect our planet's thermal balance and our climate. Reduce heat transmission through the crust and we could see a supervolcano start up. Change the compressibility of air and sea life could die, forests could become deserts, and supertornados could sweep across the planet. [Answer] To add to the other answers, a major problem I didn't see mentioned anywhere is if the pressure produced by burning gunpowder drops too low, the bullet won't even exit the barrel of the gun. That's what happens when you under-charge a cartridge, or forget to add powder entirely so the primer alone propels the bullet a short way into the barrel. If you don't notice the squib round and fire the gun with a firmly plugged barrel, the result can be anything from just a slightly bulged barrel to a catastrophic failure that completely destroys the gun and injures or even kills the shooter. That's the way things work in the world as we know it. Add the possibility that the internal pressure could go from way too low to way too high in a short time--if I understand your scenario correctly--and I would not want to use guns at all anymore. It would be like using grenades where the fuse could vary from 0.1 to 10 seconds and you'd never know which it was going to be until you'd already released the spoon. Edit: I should add that in the event of a squib, a semiautomatic or automatic weapon is not likely to chamber another round (or recock the bolt in the case of open bolt weapons). They can, but squibs are more likely to go unnoticed in relatively low recoil, manually operated firearms, or externally powered automatic weapons like chain guns and Gatling gun descendants. ]
[Question] [ A race of beings decides over a few pan-galactic gargleblasters one evening that rather than waste scientific minds on developing hyper-advanced technology, they should just build a huge computer to design clarkean devices for them. A computer of this size naturally requires a huge power source, so this is what they come up with: An enormous spherical computer is built, consisting of trillions upon trillions of densely-packed processors each the size of a brain cell. This processing layer surrounds a huge reservoir of water. The computer is placed in orbit around a large body such as a gas giant, and due to tidal flexing, the fluid heats up. The difficult part: I had originally planned for the hot water to be channeled up from the core, turned into steam and used to drive fans and so power the processing layer, until I realised that this would then involve venting the steam into space, and thus slowly depleting the core of fluid. So, is there another way to produce a giant supercomputer powered by tidal flexing? [Answer] This is straightforward. You actually want to put oceans around the outside, covered in ice so they don't evaporate. Europa, for instance has oceans a couple hundred miles deep. We already know that water will flow to follow the tidal flux, so put generators that sap power from the tides as they rush around the planet. Addendum: Venus has 900 mph winds that are driven by the solar wind scraping against its leading side as it orbits. The atmosphere is so thick that the wind drags the planet against the force of tidal locking to have a day that is 19 Earth days longer than its year. I'm pretty sure you could power a computer off of that. Addendum 2: After reading Rastlin's answer, it occurs to me that the heat of computation would create convection. For something this size, you'd want subduction cracks that let the cold water rush down into the core, and have vents that allow the water to flow past the processors, drawing excess heat from them. At the processor/water interface, you could recoup some of that energy with turbines before the coolant is released back into the ocean. It wouldn't work as perpetual motion -- you'd still need tidal generators -- but why throw that energy away? Addendum 3: If you're concerned about the tidal forces running out, you can always have other moons adding to the fun. Io has so many of it's sisters squishing and stretching it that it's perpetually molten. You probably don't want to go that far, but you probably could put electromechanical generators that convert the distortions into power. [Answer] They may want to cut down on the gargle-blasters. 1. They appear to be heating the computer's coolant to the boiling point to produce steam to power the computer. The computer probably won't like this. 2. As pointed out by other answers, tides already move the water. You could convert this motion directly to power, which is actually easier if the water is on top and the computer in the middle. This also allows your power generation equipment to dissipate waste heat directly to space, and natural convection constantly delivers cool water to the computer. You could also restrict the motion of the water to reduce the amount of energy dissipated when the computer isn't doing anything, which brings us to: 3. Tides aren't the energy source here, they're just the means of coupling it to your generators. The energy source is the computer's orbital (and rotational) energy. In placing the computer into orbit around the gas giant, you were just storing energy that would later be released slowly via tides as the computer's orbit decayed (circularizing if there's no third-body interactions keeping it in an eccentric orbit, as is the case for most moons experiencing much tidal heating in our own system). Much of that energy is in fact being released as heat in the gas giant. If the computer is being built in an existing moon, harnessing tides for power might make sense: that energy's already there to begin with, tides are just slowly releasing it. If they are constructing the computer as an artificial moon large enough to experience significant tidal heating, they obviously already have other, better ways to power things. [Answer] I don't see the need for heating. If you have tides, you can set up tidal generators. Of course that only works if your machine is large enough, which is probably larger than moon size. But it would probably have to be at least that big to experience tidal > > An enormous spherical computer is built, consisting of billions of densely-packed processors each the size of a brain cell. This processing layer surrounds a huge reservoir of water. The computer is placed in orbit around a large body such as a gas giant, and due to tidal flexing, the fluid heats up. > > > So I'd do it the other way around, find a moon, put the computer on the floor or the core, and dump enough water to cover the surface. Then set up tidal power generators to power the core. Also, a human brain has 100 billion cells in it, so depending on how many billions of processors each the size of a neuron you have, your spherical computer would not be large enough for tidal flexing. > > Now, here is the difficult part. I had originally planned for the hot water to be channeled up from the core, turned into steam and used to drive fans and so power the processing layer, until I realised that this would then involve venting the steam into space, and thus slowly depleting the core of fluid. So, is there another way to produce a giant supercomputer powered by tidal flexing? > > > You wouldn't have to vent the steam, since it would naturally cool through black-body radiation once it's on the top layer. At that point it could filter back towards the center, though you'd want to separate the inputs from the outputs somehow, possibly by having them jut above the surface, then having condenser coils spiraling downwards, which will cause steam to turn into water while traveling back to the surface. [Answer] Your computer will be powered by electrical current generated by the motion of the moon through the magnetic field of the gas giant. If a conducting object is in motion through an external magnetic field, an electrical current is produced in that object. The current produced gives rise to a magnetic field that opposes the external magnetic field. This is [electromagnetic induction](https://en.wikipedia.org/wiki/Electromagnetic_induction). This is how Jupiter's moon Europa is getting its magnetic field - it is being induced. It is not a static field generated internally like that of the Earth. Electrical currents are being induced inside Europa as it traverses Jupiter's magnetic field, and they betray their presence by changing to generate a magnetic field which opposes that of Jupiter. [![europa induced magnetic field](https://i.stack.imgur.com/3GbYj.jpg)](https://i.stack.imgur.com/3GbYj.jpg) <http://ffden-2.phys.uaf.edu/webproj/212_spring_2015/Amir_Raz/amir_raz/Magnetic.htm> Like Europa your computer-containing moon has salty oceans and within these, electrical currents are produced. Your computers energy harvest apparatus offers a more conductive path for these currents to equilibrate and so they take a shortcut through its wires, doing some work along the way. The energy is generated from the gas giant producing its magnetic field and the motion of your moon through that field. This method of generating electricity will slow the moon very gradually and so might cause its orbit to decay over many millions of years. It is not exactly tidal flexing but similar in that the energy is derived from the relative motion of the two bodies. Prior art: [Is it possible for an organism to convert magnetic radiation into a sustainable energy source?](https://worldbuilding.stackexchange.com/questions/118475/is-it-possible-for-an-organism-to-convert-magnetic-radiation-into-a-sustainable/118516#118516) [Answer] Hmm... Actually the right answer depends a lot on the material base on which your processors are built. Plus, in the aforementioned case of a bunch of cores, there's the question of exchanging data between them. Which, in fact, is more complicated than just making a core. This also raises the question about the wave - how exactly will the wave pass through the computronium so that it transmits energy to the whole depth? I assume you've got a bunch of channels in there that are parallel to the core and the water flowing through them can do useful work. Otherwise, if the water is warming at the top, you're going to run into architectural problems of transmitting energy from top to bottom, to the depth. Also, a computer this big has to have storage, possibly RAM, and interfaces for I/O. Let's go point by point: 1. it makes more sense to use optics for connectivity rather than current. This will greatly reduce heat dissipation, and will also be less expensive in terms of resources, wires have to be made of something. 2. If you do coupling to optics, then converting light to current is not a difficult task. But computing on the core will be a bottle neck, since purely optical computers are 3-5 orders of magnitude faster. So it is reasonable to abandon silicon as well. By the way, this could be a good idea because it greatly reduces the requirements on the manufacturing process - no need to chase after small nanometers with their absurdly low yield of good product, you can do for optics in the hundreds of nanometers processes. And they do not require many rare elements. 3. At this size, you can think about the specialization of individual cores. Some of them stream data packets, some of them multiply matrices, some of them look for the biggest value in an array of numbers. In my opinion for those, who are ready to build a computer about the size of the planet, the market logic of the architecture of processors and their specialization rules are not valid. It is utilitarian utility that dictates the profitability of a hybrid architecture. Two examples are Heinlein's Moon is Harsh Mistress and Groq company, who produces hardware accelerators for ML 4. Interconnecting everything-to-everything is going to be a very complicated affair. Either we make a separate network layer and dedicated cores for it (which creates practically an internet within cores), or we have to accept that cores communicate only with neighboring cores in some range (100-1000-1000000 cores). This is reminiscent of neurons in the brain. Then, either the cores transmit data in a chain (which is time consuming) or we switch to a in-memory computation approach. This is reminiscent of the game of life - each nucleus counts something and passes it on to the next step 5. Reversible computing, because of the magic scientific stuff, allows no heat to be generated during computation, as there is no loss of information. So there is practically no heat problem then. And this approach can still be done today, using ordinary silicon 6. I like your original idea with water evaporation. That's basically how the planet works - water evaporates, goes to the sides and falls down at the poles or in the mountains. If you run thermally insulated capillaries from the poles, the melted water will go to the right cores even to the equator, and from there it will go up, evaporating in the process. By the way, maybe you don't need water, but organic liquids, at least methane. Such an atmosphere is even more likely. Look in the direction of Rankin's organic cycle. And google MEMS heat exchangers - turbines can be made very small. If the fluid on your planet consists of a ferrofluid or liquid metal, the thermal exchange would be more efficient, and fluid transfer could be done by means of a magnetic field. The fluid flowing from the bottom through the microchannels in the core would simultaneously draw heat and, passing through the magnetic coils, generate current in the processors. Look at MHD 7. The cooling method you choose dictates the temperature range. But in fact - the technology you choose to make the processor is more important because it dictates the temperature range, and the cooling only has to adjust to that. Example - in p6 I talked about liquid metal cooling. If you do a bunch of radio tubes instead of cores (and darpa has done such projects at the current level of technology), if everything is heated to 400-600 degrees Celsius, the radio tubes can work without heat. And the performance of radio tubes, for reference, is 2-3 orders of magnitude higher than processors. And it is resistant to the magnetic field. That is, the free heating of the planet makes it possible not to melt, but to work quite well. On the other hand, you can go down - at cryogenic temperatures you'll be running everything with superconductors. The heat output will go down, it will be more important for you to protect yourself from external heat from the gas giant and the sun. You can make a bunch of re-reflectors of ice on the surface to shine like a mirror. You could go the way of a liquid ocean in which there would be individual cores in the form of organic cells. They do calculations and exchange their photoluminescence with each other, transmitting data. Bacteria computers are also made - you can google it. And the bottom line is you don't need cores if you're making ASICs. You can build huge hybrids of waveguides and photonic crystals that will do the computing. You feed an electromagnetic wave to the input, and you take the results at the output. It would be fun to link this to the planet's magnetic field to feed the signal amplifier repeaters inside the device. ]
[Question] [ I have floating islands with varying levels of technology that can be allowed on them, usually based on height. One of these islands has tiny microbe/bacterium that allows for food crops to be grown at a reliable rate on these islands but at a cost. It's a green goo (alternative to grey goo in which tiny nanites attack electrical applications). It relentlessly targets electrical applications (completely ignores bio electricity). Creating a vacuum or sealing away a computer offers no resistance due to handwavium reasons. Basically, if it detects an electricity in a certain way, it's going to attack it. When attacking an electrical application, it reproduces rapidly spreading like a cancer and dissolving the wiring and metal frame of whatever its spreading on. The effects are almost immediate as well. Yet at the same time it allows things like vehicles, tanks, aircraft, basic electromechanical computers/machines and small-scale electronics to work. Most of these are things that will utilize electricity in some way, but often through a battery. As such their use time is limited and dependent of batteries. In a sense electrical technology is grounded to that of the 1940s or even worse in some areas in terms of portability (vehicles count as portable in this sense). What should my green goo target to disable electrical infrastructure but allow smaller scale electronics? The goal is to have an island where power generation isn't feasible, especially for large scale devices. Things like large factories, long distance power cables, radio towers etc do not work. But something simple that can be run off a battery works. The absolute max for a battery is the size of a car or airplane battery. There exists more modern technology on other islands, but if they bring that technology down to the island that requires electricity in any capacity more than a battery, then the system bricks and the green goo attacks the machine. Some notes: 1. Integrated circuits do not work on the island except for aircraft flying at reasonable height and speed. Airships mounting a modern computer will short out/be infected by default. This isn't part of the scope of the question. It's already been taken care of. So IC's and semiconductors can be ignored. 2. The green goo dies the moment it leaves the confines of the islands. Think of the area of effect as a dome. 3. All wireless communications on the island are jammed past a short distance due to the microbe/green goo 4. Bio electricity is completely unharmed. 5. Chaining multiple batteries together should cause issues/isn't allowed. [Answer] ## It is attracted to high voltage ELF radiation Every individual appliance in a normal American household operates at 120v or less. A lot of light duty industrial equipment like welders, mills, etc. operate at 240v. However, the electrical lines used to distribute power operate at up to 380,000v. Lower voltage lines lose power more quickly than high voltage lines; they are also smaller and cheaper to make (for how much energy they can transfer), so if you want to have a central power plant that can distribute power to a whole city without being grossly inefficient, it needs to use high voltage power lines. Not only is it much more expensive to use low voltage lines, but if you don't, literally all of your power will be lost to resistance after just a few km which would make getting power in remote places especially difficult. So, if your green goo is attracted to the the EM radiation created by voltages in excess of ~240v, then you will make centralized power plants and radio towers impossible, but local generators, batteries, and a wide range of personal and industrial equipment will still be doable. If they target 120v or more, you will also disable most industrial equipment and generators. If you target 12v or more, then you also disable many household appliances like air conditioners and washing machines, and ethernet wires making both wired and wireless communication virtually impossible. If you target 5v or more, then most hand held power tools, flash lights, etc. will be disabled too leaving you with little more than pocket calculators and cellphones... though the cell phones will only work in "offline" mode because you wont have functioning radio towers; so, it is more accurate to say that you could still have tiny cellphone sized tablets, not actual cellphones. ## No need to handwave this part: > > Creating a vacuum or sealing away a computer offers no resistance due to handwavium reasons. > > > High voltage powerlines emit [extremely low frequency](https://www.osha.gov/elf-radiation), high energy radio waves. A general rule for radiation is that the lower the frequency and the higher the energy, the further a signal can penetrate through insulating materials. While the frequency of these radio waves is thought to be too low to be harmful, it is virtually impossible to insulate against. ## What about direct current? The ELF radiation I am describing is caused by alternating currents at ~60 Hz meaning that your green goo could be made to attack any AC circuit if the amplitude of radiation (derived from your voltage) is high enough. But stable DC currents do not generate ELF radiation; so, you could in theory have a higher voltage DC current that the green goo will ignore. So, if you cap it at 12v AC currents, then you may still in theory have a 120v DC powerline somewhere. But it has its limits: * Generators create AC power as a function of how they work. So, the green goo would still attack a high voltage generator, even if you are transporting the power via DC. So, high voltage batteries would work fine, for select purposes, but this is a huge logistical limitation. * DC is much less efficient to convert between high and low voltages meaning even if you produce power offsite, and tried running it in over long distances at higher voltages, a lot of inefficiency would happen trying to drop it to usably low voltages. * Changing the voltage of a DC current produces ELF radiation; so, the powerlines may work fine, but step down transformers will still be attacked by the green goo. So you can only transfer power onto the island using low-voltage power lines. Depending on how far the exclusion zone is, this will make this somewhere between very expensive and only accessible near shorelines and completely impossible. * A lot of high powered equipment by its very nature creates ELF radiation so, just because you can power a high energy radio tower or arc welder does not mean that the thing itself wont be attacked. In short, DC power will probably let you sneak above the threshold here and there for minor things, but not completely give you free reign to go over it. [Answer] Your creature isn't making a decision per-se to leave cars and small electronics alone (etc.), it simply doesn't notice them any more than we notice moderate humidity I want to expand on @Nosajimiki's answer. I upvoted it and you should too! His answer focuses on how the creature might detect electricity. His answer gave me an idea, the result is a [Frame Challenge](https://worldbuilding.meta.stackexchange.com/q/7097/40609). You don't mention the intelligence of the goo. My challenge is that if the goo has animal intelligence, then it won't be attracted to electrical production that doesn't feed or threaten it. Too much work! Not enough benefit! If it has human or better intelligence, it still won't be wasting its time on the small stuff (unless it's a bit psychopathic...). Too much work! Not enough benefit! Humans notice rain, but we don't notice moderate or lower humidity. Both are "water in the atmosphere," but one is too much work to notice while the other is pretty much impossible not to notice. I challenge that your creature is no different when it comes to noticing electricity. It might notice an operating computer or car, but it won't care. The people of your world can take advantage of this aspect of the goo's nature by keeping electrical generation distributed and electrical consumption separated. For example, a single desktop computer is operated with a solar panel. No more than X number of computers are allowed to operate in the same room or building at one time (each with their own solar panel). Thus, there is no single point of power generation that will draw the goo's notice and not a large enough nexus of consumption that can do the same (call such a nexus a "blood trail" that the goo might follow to find its source). In other words, what your people discover is that if they spread out electrical generation and consumption, its use becomes small increases over the general background hum of life that the goo simply doesn't notice. Unless there's a bolt of lightni... Squirrel! And that's when Lieutenant Rosario had a brilliant idea! The goo could be distracted by [lightning in a jar](https://sciencing.com/make-lightning-bolt-bottle-10057255.html)! Enough energy to distract the creature from all surrounding use while it's packed up and moved away but not enough to drain the government's coffers. The glass thickness is rated to give thirty minutes' time to haul butt somewhere else. Lieutenant Rosario, now Major Rosario, now leads the government's efforts to improve the grenade by souring the electricity to sicken the goo. [Answer] It Won't Work That Way Large scale electrical supply is actually more robust, not less. If you can have a battery of any size and not have it eaten by your green goo, then you can have a generator. A generator is basically just a bunch of copper wires wrapped around a magnet. The transmission lines are just copper wires. A motor is similar. There is nothing in the large-scale infrastructure that could be susceptible while small stuff like batteries and electronic devices would survive. The very worst one could imagine is that certain types of insulator or transformer oil might need replacement. You could make the insulators out of whatever works for the outside of batteries. You could make the transformer oil out of something else, since there are a huge variety of substances that are possible for such use. So there might be a period of disruption when the goo first shows up. House wiring insulation might all degrade producing a massive number of house fires. But that is easy to retrofit, since there are huge numbers of materials that will function as insulation for house wires. It happens to mostly be PVC and similar right now, but that's down to it being cheap and convenient and long-lasting. Materials like shellac and paper have been used. [Answer] # It should target electrical infrastructure, but leave smaller scale electronics. If you have some sort of mega advanced bug that is intentionally destroying a tech level, just have it be smart enough to destroy that tech level. It doesn't need to target anything tech wise, which could be replaced. It can just target size. ]
[Question] [ Eyes, ears and nostrils are shaped to facilitate their function. So what is the optimal shape for a humidity sensing organ? A paper about fruit flies ([link here](https://news.northwestern.edu/stories/2016/05/discover-sensory-system-detects-air-humidity)) explains that the insects are adapted to retain and seek water. > > "The mechanical deformation of a specialized little organ inside the > antenna, called the sacculus, could tell the brain about humidity > levels." > > > The organ expands as humidity levels rise, giving the animal information about the amount and location of water. A useful trait not just for insects but also desert dwelling animals. For them, it would make sense to have an organ (presumably on the face) entirely dedicated to sensing bodies of water. The organ would be more developed in smaller animals that retain less water than larger ones. However, I wasn't sure about it's shape... EDIT: JBH, your extensive feedback has been noted. I will do my best to describe the animal that will serve as my example. A semi-quadrupedal reptile roughly the same size as a coyote (25 inches tall or 63.5 cm) and with the general anatomy of an iguana. It is diurnal and is most active at dusk and dawn. It's long and powerful hind legs allow it to hop on the sand with ease much like a kangaroo. The animal has webbed feet covered in setae which help it move on the sand but also make it a good swimmer. It requires water especially in the early stages of its life. The humidity sensing organ replaces the pit organs found in vipers, located in between the eyes and nostrils. Water heated by the sun evaporates during the evening making it easier to detect potential waterholes from a long distance. [Answer] # Nose, trunk or antenna shaped. This is yet another case of the ever running show "nature beat us to it". You're completely right that the ability to find water is something useful to have, especially if you're an animal that lives in a desert or dry climate region, or if you can't reproduce without a body of water. In fact, it's so important that camels and mosquitoes can do just that. Camels can smell water over 75 km away by smelling the spores of microorganisms that thrive in the water bodies, carried far away by the desert winds. Elephants are also on this list, with their potent noses capable of smelling water 20 km away. Mosquitoes meanwhile, lack noses, but instead have antennae filled with special hairs capable of detecting water vapor, allowing them to find the water they need to lay their eggs in. So apparently, there's no need for complicated swelling organs. A pair of sensitive antennae or potent noses with plenty of olfactory receptors, prehensile or not, are two examples of effective, natural-selection-approved water detecting sensitive organs (and they can even detect the smell of other things too! Talk about neat). [Answer] There are a number of options available to an organism though figuring out the evolutionary pathways to any of them is likely a major undertaking, but several means of measuring relative humidity exist that are well within a biological entity's materials palette. 1. Twisted hairs This is how pinecones work: opening when the air is dry, closing when it is wet. Bundles of tiny hairs that are coiled around each other will slacken when moist, loosening up; contract when dry, tightening down. From there any conventional nerve bundle that responds to the tension of the system will produce a proportionate response to the level of dryness. It's got a long delay from change to stimulus, and it's approximate at best - but aren't all organic sensory organs? 2. Biologic Psychrometer Psychrometers work by measuring the difference between wet-bulb temperature and dry-bulb temperature. Assuming the creature can tell how hot/cold the outside air is, all it needs is for some of those heat-sensing organs to be submerged in water, either by finding an external source of water that it's adapted the instinct to dipping one set of temperature-sensors into, or excreting something that covers a portion of the sensor organs. The brain is then adapted to interpreting the difference between those two temperature signals in order to produce an understanding of the relative humidity. As long as there's an evolutionary advantage to doing so, it'll happen on its own sooner or later. Binocular vision works in a similar fashion: two distinct signals are merged/cross-interpreted. ]
[Question] [ In the vein of the Expanse's juice or the Forever War's submergible tanks, what types of body or cockpit modifications would allow a human to survive high G maneuvers in short impulses in a combat setting? Note in this case I am not looking for major coverage in the vertical (+/- Y axis), rather the lateral planes. Some context. My mech pilots are basically flying glorified hover tanks that can rocket around quickly. If you've ever played the later Armored Core games, you'll know what I'm talking about. Maneuvering is handled by a series of short high impulse/high G rockets. General movement is a much softer powered flight of sorts, the main takeaway is that the "legs" of the mech never touch the ground in a combat or self-powered transport mode. That said, no one is going to be straight line accelerating at high G for more than a minute at most, such a maneuver would essentially be teetering on the edge of death and not a tactic taught or routinely employed at all. These quick maneuvers happen when an opponent has closed in very close. Engagements don't typically last more than five minutes at max. Rapid direction/vector changing does happen during these moments. Essentially the mechs are zipping around each other like ice skaters. Some tech level surrounding the pilots/world: 1. Early cybernetics. Signals from the brain passed into a microchip can allow prosthetics to move in certain predictable ways for daily and limited combat use. 2. Based on the type of person/ how they were born, their organs, limbs, nerves etc can be regrown with exception of the brain. Decent amount of stem cell research in this world. 3. The mechs/tanks in general aren't using composite armor all that much for defense. The first layer of defense is essentially a particle shield that slows or disintegrate parts of an incoming warhead. The second layer of defense is copious amounts of explosive reactive armor to defeat stripped/heavily damaged warheads that brute forced their way through the shield. Lastly some mechs/tanks might have a final layer of composite armor. Though there's decent numbers that have just structural metal under ERA blocks. 4. Low level gene editing. 5. Advanced recoil dampening systems for weapon systems on all levels. From the lowly rifle up to tank/mech guns. 6. High impulse thrusters that don't melt or crack under repeated use (near future material science). 7. A system in place that allows a person or pilot to be flooded with fluids at various points in their body. Requires multiple small tubes throughout the body. System isn't experimental and is routinely used in emergency medical situations. 8. Virtual prosthesis/bionic eyes. Sight is nearsighted only, however. Significant drop off past a few meters. Good picture quality, however. 9. Advanced cameras,optics,sensors etc. Pilots, tankers, mech pilots, ship captains etc don't need the use of windows or clear material for navigation. Cameras and visual image stitching has allowed fighter pilots in particular to fly with completely enclosed and more aerodynamically suited cockpits. Basically no one is using glass/clear material for navigation anymore for combat. The screens that are used are optimized for long term visual use and are detailed enough to capture very small detail. Added benefits of image processing are baked in such as zooming in, different encoding/color options etc. Body modifications can start at or even before birth. Edit: The maneuvering thrusters aren't constantly firing off in a certain direction like a rocket engine, rather there is a massive burst of thrust in a short amount of time. Time could range from less than up to a second and a half. The mechs make heavy use of momentum to "skate" across the battlefield. Thrusters can be toggled/chained to a very limited degree in the same direction at a high thrust output, they however can use a much lower impulse over a longer period of time to essentially glide much more smoothly. In this mode its more akin to general movement than heavy combat maneuvers, it's the equivalent of a fighter jet cruising to combat and then actually pulling high G maneuvers during combat. There's significant drag as well. It can be safely assured that the Mach barrier will not be crossed in sustained flight/chained maneuvers on a single vector. For the purposes of this question, I am trying to find something that allows a pilot to survive high near instantaneous G forces/jerk. [Answer] This is a fun question for a number of reasons, but I think the biggest reason is the wide range of G force limits depending on impulse duration. With impulses below 0.1s, the sitting human body can withstand up to 35 Gs in the forward direction, and 14Gs in the lateral directions. Now, obviously as we approach 1 minute impulses the limit drops to the subscribed 10Gs, but that’s a physical limit before extreme stress and 20ush Gs the limit before injury. It is likely though that the vehicles will never need to achieve so long an impulse. For each second of impulse at 10Gs, the vehicle is achieving nearly 100m/s velocity. In tactical combat terms, that is very fast. Considering your desire to have these vehicles moving with such constant change in direction, there will likely only be impulses in the range of 0.1 to 0.5 seconds. In this case, the vehicle could safely provide impulses up to 14G in the lateral planes, up to 20 in the forward direction. Given this information, the real question of the pilot safety measure probably has less to do with the actual speed of the vehicle and more to do with the physical security of the pilot’s body and limbs. At these rates of acceleration, it would be pretty devastating to the body to have arms free to flail around, or head free to get rock violently from side to side. Even the strong human doesn’t have musculature or reactions to control their limbs in these conditions. It stands to reason, then, given the series of technological items you’ve provided, to leverage that tech to keep the pilot as safe as possible in the vehicle. ## Cybernetic Controller Since the user can send commands to the vehicle from their brain with electrical connections, it is not necessary to have the user operating the vehicle with hands or legs. Given this, during combat, the pilot should strap everything down and utilize the remote-control functionality. Normally, this would be problematic for sight-lines, but there are advanced imaging systems that would allow for a full 360 degree display to be pot up on a screen that only takes up the pilot’s static field of view. Alternatively, the orientation of the camera could also be controlled by the remote brain interface. \\ ## Blood Flow \\ One of the big issues with high-acceleration maneuvers is the tendency of blood to pool in unwanted parts of the body. While this is less of an issue in the lateral planes for a sitting human, it can’t hurt to account for it. You have already provided for fluid circulating apparatus effectively built into the human body itself, so take that a step further and use it to recirculate blood to where it needs to be in the event of a high-acceleration maneuver. Using the human-body interfaces and external bypass pumps, the blood flow can be regulated to stay consistent to the brain and the rest of the body regardless of velocity and acceleration. This would be hugely effective in increasing the tolerance of the human body to these kinds of high-thrust situations. ## Breathing Another major issue to high-acceleration is breath control. The body will weigh X amount more in the opposed direction of acceleration when accelerating and this can impede proper breathing. At lower values of G this can be control with shallow breathing to both eject CO2 and allow room for air to enter the lungs. At higher values, this becomes more difficult. Using external masks/etc. and pumps to extract CO2 and push O2 through the nose and mouth would work. However, it may not be needed here, given that the pilot has access to blood recirculation tech. Using this, the external pumping apparatus could infuse oxygen directly into the bloodstream if O2 Saturation drops below a certain point. The effect of this system would again greatly extend the safe acceleration metric for a human body. ## Impact and Bruising Even using the most effective restraints can leave a human body vulnerable to the forces of impact that would be experienced due to such acceleration. The greatest source of impact will come from the restraints themselves as the body is jerked around. For most vehicles this sort of thing is reduced by a suspension. In the case of our pilot, a suspension should be used around the entire cockpit if at all possible to reduce the relative shock of sudden jerking movements. Given that most combat maneuvers should be relatively short, on the order of 0.5 second impulse or less, a suspension of the cockpit could be very effective. Some methods for achieving include using “floating” the cockpit in a water barrier, electromagnetic field, old-fashioned mechanical springs, the advanced recoil-reduction systems you've already set up, or all four. Since the imaging systems allow for the cockpit to be completely enclosed, there’s not a reason why the suspension system can’t fully encompass the cockpit and assist with all of this thrusting around and jerking. ## Potential issues Marrying all of these technologies would make for a very impressive system to reduce the stress and fatigue on a pilot of one of these vehicles. The biggest issue with a lot of these systems is their complexity and cost. High complexity would mean relatively high probability of malfunction, and cost would limit the throughput of these vehicles in production. We can avoid the malfunction issue somewhat with redundancies, but if we are basing the function of the combat on entirely electronic visual media, if we lose all the cameras or electrical systems or breach the cockpit, the vehicle is out. Of course, at that point, the pilot is likely also dead, so it may not matter. ## Conclusion You’ve already laid the foundation in your setup to provide for these support systems, and I think that merging them with these uses in mind will make for easy resolution to your issue. [Answer] If the pilot can be encased in a rigid capsule inside as little as a few centimeters of fluid at body density (i.e. barely denser than water), they can take 10 G or so at right angles to the spine for more than a minute at a time with no further modifications needed (in fact, with training, this is possible with common acceleration couches like those used in, for instance, the Mercury capsules of the early 1960s -- the early Mercury astronauts, flying suborbital on Redstone, took 8-9 G for a couple minutes during reentry and most remained conscious). I would point out that if you can reach 10 G for a full minute (= 6 km/s less gravity and air drag losses), you have a suborbital spaceship, not a hovertank... [Answer] I am assuming these maneuvers are very brief and made with minimal warning, like to dodge an incoming missile or whatever. In that case, there's not really any way to predict which direction the acceleration will be in. This means the trick space capsules use, where the crew lays almost supine, such that the G's pull toward their back instead of down, isn't feasible. With this in mind, the most dangerous G's aren't high positive G's, they're negative G's. Instead of pulling blood out of the brain, negative G's push blood into the brain. Permanent damage is much more likely. Wikipedia says the limit is around 2 to 3 negative G's, limited by the strength of blood vessels. Pull too many negative G's, and you risk bursting them. I have two ideas to remedy this, one cockpit-related one biology-related. If the pilot sits in a little capsule attached to the rest of the mech via springs, the springs will take some of the acceleration, so long as it's brief. Might be enough to mean the difference between discomfort and an aneurysm. If the pilot is genetically-modified to have stronger and/or more elastic blood vessels, he'll be able to handle higher negative G's before one bursts. [Answer] Head (Brain) in a Jar [![enter image description here](https://i.stack.imgur.com/T1FX3.png)](https://i.stack.imgur.com/T1FX3.png) You do not say it, but you seem to want something more extreme than the flight suits and chairs that fighter pilots use. One problem with high G's is it makes blood rush away from the head and go somewhere else. To solve this simply shop off the head so there is no "somewhere else": > > . . . the orientation of the camera could also be controlled by the remote brain interface. > > > > > nerves etc can be regrown with exception of the brain. > > > Rather than have their whole body in the robot, the pilot only puts their head or maybe just the brain in the robot. The head or brain has a life-support system that is much more robust than a puny human body. There is also a wire going into the brainstem and into the nervous system of the robot. While the the pilot is piloting their body is kept alive. When the pilot is finished piloting their head or brain is reattached. [Answer] The question to ask to decide what the maximum g-force a body can take is not the one you might expect. It is this. What happens when you drop a wrench on a submarine? A sub is very nearly neutral buoyancy. This means that with only the tiniest amount of work it can keep the same depth in water. However, the parts of a sub are not neutral because they are of widely varying density. An impact to the sub causes the denser objects to lag behind the rest and slam into the side of the sub. So too the parts of a human. Bones in particular are denser than the remainder of a human. There are also other organs that are of different density. A [concussion](https://www.cdc.gov/headsup/basics/concussion_whatis.html) results because the brain is different density to the fluid it floats in. Thus an impact to the skull tends to cause the brain to move out-of-place, possibly resulting in serious harm. You want a body with minimal differences in density. Starting with bones. You need to replace bones with structures of the same density as the rest of the body. Then, to get higher and higher acceptable g-force, you want to reduce the density differences to smaller and smaller values. You want [Kif Kroker](https://futurama.fandom.com/wiki/Kif_Kroker#Physiology). Kif does not have bones. He has a series of fluid filled bladders. In addition, he is pretty squishy. So put him in a form-fitting shell that will hold his normal shape. And give him a ventilation system that will let him breathe out rapidly when he is accelerated. He will simply compress a little. The air will get squeezed out of his lungs. As long as the acceleration lasts no longer than he can go without breathing, he will be fine. ]
[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 1 year ago. [Improve this question](/posts/223678/edit) I came up with an idea for some fanfic in the DC/Superman universe. I'm not going to use the name of any DC characters, just allude to them to try to stave off any legal issues, and I don't plan on selling the stories anyway. But that's not the question. My character is a second or third tier super hero. He has a bunch of super abilities similar to Superman, but nowhere near the strength or stamina. He can fly, but only a couple of miles. He can see through some things, but not very well and not through any metal. He also has a few abilities Superman doesn't have, so not a straight ripoff. Part of the story will be about how he fights crime in his small-ish town of 200k-300k people, but generally stays within 100 miles of home, not doing anything international or even national. This is also his full-time job, so he only uses his real identity when he wants to relax or otherwise be incognito. The other part of the story is about how he is a bit of a screwup, as he's still learning his powers, what their limits are, and how to expand them. It's intended as a comedy, rather than a serious "superhero" story, if that makes any difference. I'm trying to figure out how he pays rent, buys and fixes his "uniform" (it's not costume, pfft), and feeds himself without being rich. He grew up middle class and I don't want any financial windfall to "deus ex machina" his modest lifestyle. I also don't want him eating ramen all the time. He's not a genius, he graduated high school normally, and went to some college, but decided it wasn't for him as he couldn't focus on schooling while learning of and about the new powers he got the day after he graduated high school. I've considered bounties for the criminals he brings in, but first time thieves and murderers aren't going to have a bounty. And he isn't the type to go after deadbeat parents, either. I doubt a small time vigilante would be able to land a deal with the local police department, and I don't want him to be a cop, either. "Private eye" is so over done, it's not even funny. Again, "super hero" is his one and only gig. Rewards are good, but not everyone gives a reward, and he's not going to be sniffing around for a lost pooch, either. I could go with a semi-rich, private backer, but there's a lot of strings to that. Maybe I can play those strings into plot points, but I'd rather my hero be independent. He's also not the mafia, requiring protection money from the city or individuals. I don't have any plans for a local "super friends" kind of thing, but even if I did go that route, it would have to be internally funded through legal means and one of them not "just happening" to be rich. So what other ways can my hero support himself by catching bad guys, and without skimming some off the top of what he returns or protects? In other words, how can this guy be a superhero without some other full time employment supporting his crime fighting efforts? Edits: I forgot to mention that I don't want him to be like Captain Amazing in the Mystery Men, who has NASCAR-esque patches on his outfit. Besides, he's a bit too small-time and local to get any real sponsors. Ok, so maybe local sponsors, rather than Pepsi, like Lance Hunt lost, but it's a bit too commercial for my/his taste. Then again, it might be funny to have "Bob's Bass and Tackle Shop" as a sponsor. Also, my hero isn't impervious to pain or injury. He can get burned, broken bones, bleed, feel pain/cold/heat/, and more, just at a higher threshold than a normal human, but not at a Superman level. He also gets tired and needs to eat. He might be able to carry a grand piano up 5 flights of stairs by himself, but he'll also need a drink of water, eat a snack, and take a 5 minute rest before doing anything else. He can carry someone with him during a flight, but only for short hops. [Answer] Social networks AND a fundraiser He is a real dream of golden-era comics - a superhero accountable to the public. He wears an action cam when fighting crime, and uploads the records to YouTube. He is getting views (and is paid for that) and he explicitly asks for donations. It would be an interesting balancing act to keep his act public, but his real identity secret. To suffer the trolls online and not to give in to unethical proposals for quick cash. [Answer] Youtube/Instagram/tik tok -Everyone will think what your superhero does is a stunt/CGI/act. -Sponsor money, Adverts money, Funneling clients (sell superhero programs like training routines and all that stuff, plenty of people on youtube already sell training routines to look like superheros or skin routines to look like disney princesses) -A surgeon posting videos on youtube can easily make more money than a surgeon who does actual surgery on people, 10'000 dollars a month is a low end growing youtuber with good marketing but not a big following, can easily get to 200'000$ a month for medium-big youtubers. -Pay a good video editor and your superhero will only need to work on his youtube career 3-4 hours per week, the editors will take care of the rest. -Youtube can be anonymous, no one forces you to show your face and you can wear a superhero mask. this is an estimate of how much an youtuber like Shadiversity makes in a month from video advertisments alone, an upper end of 13k. With sponsorships and book sales and other merch, plus the patreons and other form of donations someone like that can easily get around 15k to 20k a month with very little work. [![enter image description here](https://i.stack.imgur.com/FKYAs.png)](https://i.stack.imgur.com/FKYAs.png) [Answer] He works construction. And he is with the union, who is very happy to have him. His super powers make him a huge asset especially with certain types of demolition jobs - he is very durable and the jobs are less dangerous for him, and certain types of job are a good fit for his powers. The union limits how much he does because they want the regular workers to get some work. That is fine with him. Also the fact that he is with the union means that job sites that want him must use all union for their other jobs. But it is a good gig for him and also great for the union and the workers they represent. The bosses like him because he keeps the union relevant. The workers like him because besides doing the dangerous stuff, several times he has saved people on job sites and one time got pretty messed up doing it. Plus he is a good guy and not full of himself. --- This would be good for your story too because his regular gig is construction. He is there every day and he has his buds that he talks with at lunch. His friends from work sometimes help out with his crime fighting. [Answer] # Deliver Boy: This guy does a food delivery service, one where he can pick up orders anytime he's free and drop off food. If he can fly, he makes record time and bypasses all the traffic to pop over to the next delivery house. If you want him to use his fame, he can have his OWN service (since it's local) and people can have the privilege of getting their delivery from the local superhero. # Personal appearances: Timmy's having a birthday this week, and Timmy's dad promised Timmy he'd have a real live superhero at the party. Certain wealthy women might want to be seen dating a superhero to bolster their ego or intimidate an ex-husband. And who can forget the local steel mill who has an annual picnic with a prize for the strongest man to bend a bar (it's not like a bigger superhero is going to show up). *Besides, there's always the fun when a local drug lord or highjacking crew decides to hire the hero to lure him into a trap. I suggest getting the money in advance and having a firm cancellation policy.* [Answer] There are a bunch of superhero compliant ways to earn money on the job. # Corporate sponsors. Crime sells, and lots of corporations would love to sponsor someone who goes to crimes, says some pithy statements, and beats up bad guys. If you're reasonably good you could go for more ethical sponsors aligned with your goals, like a home security one, and you could advise people on how to secure their homes against supervillains. # Security Supervillains know that the best way to get lots of cash is to attack rich people, so you could certainly get jobs protecting rich people from supervillains. This gives you political influence as well to fight crime. Flying some rich person from place to place and giving a speech about how crime is bad and people need to fund the police more and end poverty is pretty superheroy. # Donations They could set up a patreon or a gofundme page to help pay for their superheroing, and collect donations. People are often willing to pay to fund their heroes. # Taking criminal's stuff Criminals have lots of money. The superhero can beat up drug dealers and take their cash for their own uses. # Ask people for cash If they're stopping supervillains from doing millions or billions of dollars of damage they can just ask people for cash. Go to community centres after big attacks like churches, town hall meetings, whatever and just say you need a couple thousand to repair your costume and equipment. People aren't stupid. They can pull together to get a couple thousand if it means a supervillain not destroying their city. [Answer] ## Many jobs Q: "I'm trying to figure out how he pays rent, buys and fixes his "uniform" (it's not costume, pfft), and feeds himself without being rich" Artist and stunt man in low budget movies One property superheroes have: they are handsome. Your superman will have roles in movies, the real thing instead of special effects allows for a low budget production. Security Trivial. People with superpowers would have a great career serving as police, work for private security companies, or detective agencies. Museum guard Superman would do great in museums of modern art, to protect the modern artworks from vandalism. Superman is very quick ! Kryptonite dealer Little known fact: Kryptonite is a fantastic hair growing formula. Superman knows where to find unlimited amounts. He can put advertisements and make money treating e.g. Bezos. Power pylon repair man Superman can do some jobs quicker and with little effort. The electricity won't matter, it does not have to be switched off while Superman does the repair. Cleaning windows on skyscrapers For Supermen, cleaning sky scraper windows this is peanuts, of course. ]
[Question] [ Most humans have both arms and legs. This arrangement is quite useful out in nature, but it seems like as technology advances, this anatomy is becoming less and less necessary Furthermore, space travel will, at least in worlds that respect conservation laws, need to be as low mass as possible. And, it seems like removing unnecessary limbs would be a good step in that direction While it seems like we could easily thrive with just the arms or just the legs (especially with the right adaptations), I have some doubts about removing all four limbs. Though many people have lived without limbs, I feel that a wholly limbless society may not be able to survive These humans would be genetically engineered, and so could have some sort of simple adaptations to make up for the lack of limbs. For the sake of lightness, they are around 30cm tall, with smaller organs and very little fat Could these humans thrive without arms or legs? [Answer] Nerve Ending Interface. [![enter image description here](https://i.stack.imgur.com/ROkSj.png)](https://i.stack.imgur.com/ROkSj.png) The Beaners are suitable for space travel because the spaceships are custom built for them. They wear neural readers on each stump that are used to control things around the ship. They still need limbs to move around ala XCOM MEK troopers: [![https://static.wikia.nocookie.net/xcom/images/f/fe/XCOM_EW_MECTrooper.png/revision/latest/scale-to-width-down/423?cb=20140121210735](https://i.stack.imgur.com/WGUXx.png)](https://i.stack.imgur.com/WGUXx.png) They save weight because they do not need limbs for every activity. The ship carries less than 4 limbs per person. And those limbs are lighter and stronger than meat limbs. [Answer] # it's probably a bad idea. While it's not impossible to live without the limbs, especially so in a society with non-limbless people there to help ([Nick Vujicic](https://www.bbc.com/worklife/article/20150318-leading-without-limbs), born with only a foot, comes to mind), it is far from an optimal choice. To live without having limbs normally means you're sacrificing a lot of things if you don't necessarily have anyone to help you: * movement speed. You might still be able to go places, but you're not gonna be fast at it. To be able to move at a decent pace you'll need some sort of electric wheelchair, and for it to be specifically made so that you can get on and off of it and use it by yourself. * height. A good chunk of one's height is in their legs, you're likely not gonna be able to see above 1m tall grass. * thermoregulation. Your limbs constitute a meaningful part of your body's surface area, and also plays an important role in dissipating heat. If you can't keep yourself cool through other methods, you might be at a risk. Cases where people have no limbs whatsoever they need to change clothes regularly to avoid problems like overheating. * proper ability to use nearly every single bit of technology today. Things are normally made with your average human in mind, meaning that you're naturally at a disadvantage if you have no hands...or arms... Or legs. You'd need to essentially adapt most pieces of technology to the new human body, or what's left of it. * competence in zero Gravity movement. In the ISS the predominant method of movement is to basically use your limbs to swing/push/pull your way around the station and outside of it in case of things such as repairs. Your bean humans will have to hope they can bump their heads or waists in the right way just to go from a wall to the next, and won't be nearly as dexterous at it. External repairs would likely require machines, since they'd have basically no way to cling to the station without any limbs. Overall, it'd be a pretty bad idea. It limits their competence at moving around, limits their ability to function properly in a warm environment and limits their ability to use technology quickly and efficiently, or to do many tasks that require, well, limbs to be made, such as clinging to the hull of a station while doing repairs in the vacuum of space where your mouth and nose are within the confines of a helmet and thus have little to no capacity to be used to hold anything. It's just a bad things overall. Sure, they'll survive, because we can survive without limbs, but we can also survive as tetraplegics, because we have people that aren't in the same boat to help us with the problems that come from such conditions. If you want humans adapted to possibly be compact and you have a high enough technology for the necessary changes here's what you do: 1- let them be born normally as any human would. 2- let them live normally until they're around 25 years old, at which point their brain and body will be fully developed. 3- surgically extract their organs, brain and spinal cord, and put those in a specialized mechanical body that's stronger, more agile and much more capable at keeping said brain and organs healthy and protected on earth, in space and potentially even in other planets. 4-put them into a rehabilitation center so they can get used to their new, mostly mechanical superbodies. Basically you turn this: [![enter image description here](https://i.stack.imgur.com/apHRH.png)](https://i.stack.imgur.com/apHRH.png) Into this: [![enter image description here](https://i.stack.imgur.com/pwS5k.jpg)](https://i.stack.imgur.com/pwS5k.jpg) And from there it's a breeze. Need them to be a little more compacted? Disassemble their limbs and non-essential parts of their bodies and store them elsewhere. Need them to perform a specialized function where extra limbs would be helpful? Strap in an extra limb, or 2,or 4. Need them to work in outer space? Rather than an entire suit, just attach the specialized life support systems directly to their bodies. Add some thrusters to their legs and arms while you're at it to ensure they can travel freely in space without worrying about being bound by safety cords or being trapped forever in space if they accidentally loose their grip and end in open space with nothing to hold onto. For all intents and purposes they should have all that's needed to cling to and navigate the outer stations properly and efficiently. Most important bonus: you can't have a nose itch while in outer space if you Don't have an organic nose with nerve ends on it. [Answer] Q: "These humans would be genetically engineered, and so could have some sort of simple adaptations to make up for the lack of limbs. For the sake of lightness, they are around 30cm tall, with smaller organs and very little fat. Could these humans thrive without arms or legs?" Not a good plan to let the infant be born without limbs At birth, you don't know if a child will become an astronaut. In your world, people would be predestined to become astronauts ? Are they born in space ? I see a few biological hurdles that have to do with the brain and the connections needed for artificial limbs and balance. A genetic change involving the brain would be complicated. In the case limbs are present, your brain develops during life, to handle two legs and arms. By applying genetic changes only to remove the limbs, the infant will never need to learn any concept of "having limbs", from the moment it is born. Nothing is prewired, you "put limbs on". For brain-controlled devices (nicely illustrated above), you'd need neural pathways to connect to. You don't walk and fight comfortly with a joystick. But the genetically altered child was born without neural pathways to control a pair of legs. There is no connect for limbs motoric control in the brain, there may be no balance system feedback, probably the balance system won't develop altogether. Amputate the limbs only when neccesary, and ask for permission first Forget genetics. Let a human be born with arms and legs. Let it develop. Then you could mount the human onto something bigger, and stronger, keeping the arms and legs in, preferably (e.g. Earth applications, great strength etc) or.. you amputate the limbs (voluntarily) to prepare for space travel. In that case you choose for that, as an adult. Great advantage: you now have a person with trained legs.. and all you need to do, is plug in your exoskeleton limbs to already developed neural pathways. It will require far less training than a limb-less person needs. Probably, only astronauts would be this mad Space travel will be a strong incentive, to undergo the procedure. It will have to be researched, though.. Some day, the astronaut will return on the home planet, in gravity circumstances, the astronaut would need good technology. In Earth culture, the astronaut will want to look attractive, requiring android limbs of good quality. [Answer] I think this query is predicated on the assumption that a human's arms and legs represent a significant source of mass that needs to be eliminated during spaceflight. Think about how massive even our modern ground-to-orbit vehicles are. They are far more massive than the combined body mass of their human crews. Now think about the space shuttles, which mass well over 800 thousand kilograms, not even accounting for their fuel and booster stages used to enter orbit. Now, we haven't even mentioned that the game rather changes once you are no longer in a gravity well. In microgravity, getting around actually becomes a lot easier, or at least a lot less energy intensive. The mass of the craft and its contents essentially equates to fuel cost; the more massive the vessel, the more energy is needed to accelerate it the same amount. The mass limitations on what modern astronauts can bring with them on flights is mainly a result of our primitive spaceflight technology, and the fact that we have basically no industry in orbit and must manufacture everything planetside (people included), and ergo must shove it up out of a fairly steep gravity well by brute force. There are far more efficient ways of getting resources into space (constructs and people alike), including just creating them there in the first place. Anyway, this has been a verbose way of saying that people's arms and legs are not something I can see future astronauts worrying about the mass of, especially as technology advances, as I assume it has in your story. If someone wants to bring along, let's say, their small collection of android hard drives on a space mission, I see no reason why they should not be allowed to. If someone wants to bring along their arms and legs that they were born with and are a vital part of their physical being, you had best let them. Now, I don't know what kind of world you are building in which space captains are thinking about cutting off people's arms and legs to save on mass, or even just breeding a race of humans with only torsos and heads, but if you really are that impressively stingy about mass, then there are better ways to eliminate it. A human's arms and legs just aren't that high a percentage of their body mass, especially for obese people. The torso is the most massive part of the body. If you're so determined to eliminate flesh mass, you might as well just decapitate everyone and put their heads on advanced life support apparatus, or even just rip out their brains and put them in life support tanks. And who says they need to be conscious during flight? You could do away with the bulky life support systems and just freeze the heads or brains until they reach their destination, where they can be given new bodies, if our medical tech is at that level. In fact, while we're talking about ripping people's brains out, you might consider just scanning their brains instead and emulating them aboard a computer server. Virtual humans take up virtually no mass, and can be duplicated or backed up any number of times. The humans who had their brains scanned might as well just go on living their ordinary human lives back on Earth (or whatever planet you are setting this on or at) while their computer-emulated replicants are out crewing a spaceship. And that's even assuming the ship needs a crew, since if you're going this rout, which I'm not saying you should, the ship could very well just be a single machine intelligence, human-based or not, and depending on its purpose, could be as small as that car that Elon sent onto a Mars-intercept trajectory, or even smaller. It could even be a single intelligence controlling a swarm of bug-sized machines sent establish a base on an asteroid or something. So, sorry if I got a little carried away, but the short of it is that if you are trying to eliminate extravagances, such as people having limbs, where do you stop? In a way, our organic human bodies are extravagances, inefficient contraptions given us by nature's trial and error, but it is nonetheless easy to see our spacefaring descendants spending that truly tiny amount of extra energy to bring their organic bodies along with them. And that's the other thing. I don't know what kind of energy economy the people in your story possess. Being so stingy about mass to the comical degrees discussed here, and to have such arguments be even slightly justifiable, they would need to be at or around the same technological level that we are now, or lower. Advanced spacefaring civilizations will surely have far greater access to energy than us primitives. Space travelers of the future might be within their rights to bring their whole organic body along with their shipping-crate full of lead ingots and their granite mansion on a space voyage, because people just don't care. The extra energy needed to accelerate the additional mass just isn't significant enough to even put a dent in the ship's fuel readout. Especially if the society in your story has access to something like antimatter propulsion, or goodness-forbid black-hole engines. And lets not even talk about how you might not even have to carry your fuel with you during flight, but could instead use various remote-propulsion techniques such as light sails pushed by lasers. Basically, there is no point in creating the bean humans. It may be possible to function normally without limbs in a technologically advanced society in which you can have robot limbs or just live permanently in VR, but lacking limbs confers no advantages, and the proactive work needed to surgically remove preexisting limbs that the person will be literally and emotionally attached to, or the even greater feat of genetic engineering needed to create humans born without limbs seems like an effective barrier to having a limbless humanity. Safe travels, fellow builder. sources: <https://www.nasa.gov/pdf/516059main_ALG_ST_SSA-Mass%2012-15-10.pdf>) [Answer] # Why Not? Given advanced technology, I would ask why humans with fleshy limbs would fare better than ones who are given access to mechanical ones from birth, with easy replacement parts and a wide variety of body plans to choose from. Given sufficiently advanced and reliable equipment, moving human pods about in a hostile environment is much safer than trying to convey entire full-size humans, vastly less resource-intense, and gives much more leeway to create a body plan as simple and reliable as possible to protect the most important thing - the brain - as much as possible. EMP sufficient to disable advanced tech on a spaceship or alien planet will be equally lethal to a normal human as to a "reduced" human. CYBERMEN: A sufficiently advanced society venturing out into space, new worlds or failing old ones will need to be able to rapidly adapt to new environmental conditions. The simplest way is to have the essence of the person in a small, transferrable (and preferably G-force and shock resistant) body. Direct neural interface enables seamless connection to new equipment, and all the team can be kept as safe as possible wherever they are. DALEKS: If you really think small limbs are of some benefit, you could have tiny limbs or tentacles, I suppose. Perhaps there are some ineffable qualities of humans that require organic interfaces to the brain to preserve the nature of what it is to be human. Such a tiny person would have some minor functionality, but it wouldn't have to look at all like a human, and such limbs would really only be desirable if electronic interfaces and equipment were unreliable. [Answer] # Your humans are modular An ordinary human is made up of cells. These humans can move and rearrange their cells. The ordinary networks of actin and motor proteins that allow cells to move in the human body have been redesigned to allow directed motion from one cellular address to another. A complex set of microscopic transmission links allows them to navigate the way. Every extracellular matrix protein in the body has been designed to zip and unzip almost instantly. Your humans may be called "amoeboid" by the ignorant, but they are not simple blobs of flesh. They are capable of coalescing to a nice round blob form while riding in a space vehicle, or generating myriad pseudopods each with fine dextrous control, or even duplicating a small human with arms and legs for artistic reasons. Their coordination and motor cognition is immeasurably superior to that of their ancient forebears. [Answer] I have a hard time seeing a benefit in removing everyone's arms and legs genetically just to save energy for space travel. Even if the species lived only on space ships, they would still face "gravity" whenever they accelerate. Unless they live in space ships that mostly float around instead of traveling somewhere, legs would be useful to keep oneself mobile. And arms tend to be useful to touch stuff like buttons or move food into one's mouth. The technology that would be required to make not having arms and legs as a species a minor issue would be incredible advanced, reliable and available for everyone. With such technology around, why not simply remove all biological matter and live in a space and energy efficient computer simulation? Without such almost magic technology, reducing the body size seems the better way. Arms and legs (only) make up about 20% of a human's weight. My quick (and quite possibly wrong) calculation suggest, reducing their height by about 10% also saves around 20% weight. But lets not nitpick, let's just assume the choice is between removing their arms and legs versus reducing their size by half. Doesn't sound hard to choose, I think. [Answer] Who needs organic limbs at all? Once you have really efficient life support systems and cybernetic interfacing, why on Earth (or why on any planet) would you want to be limited to the one original set of feeble, damageable, mortal meat-on-bone appendages? Rather just wear whatever body suits your needs at the moment. Whether that is a fully organic human body made to order, or a cybernetic body that can go where no human can possibly go (fancy doing the backstroke in a lava lake?) or how about making your body a nice, shiny, superluminal spaceship, with all the accessories? I've always dreamed of exploring the galaxy like Helva (XH-834), a woman locked into a cyborg shell in infancy to become the 'Brain' of a starship, the ship who sang. [![enter image description here](https://i.stack.imgur.com/2wcbr.jpg)](https://i.stack.imgur.com/2wcbr.jpg) [Answer] Yeah they would still need arms and legs because even in a microgravity environment people would still need to move objects and manage food and hygiene around. How could they do it without limbs? And artifitial gravity could make genetic modifications into a bizarre appearance or the creation of a bizarre race of people unnecessary. [Answer] Survey the limbless people to find the truth All these questions, answers and comments are made by people who have all their limbs intact. You should make a survey and ask those people who have lost their limbs. They will tell you what kind of hell they are going through. Also survey those people who have artificial limbs and ask them * How happy and easy they are feeling with artificial limbs compared to original limbs? * Are they feeling pains in different seasons? * Will they recommend that other humans also get artificial limbs? Limbs are not for movement only Real limbs are parts of body with sensors gathering information for further processing. Sensitivity Artificial limbs do not have sensitivity as the original limbs. You will loose a lot of information which could be harmful in certain situations. Pleasure You touch something nice (run your imagination) with real limb and artificial limb. Can you get similar pleasure? ]
[Question] [ Basically I just want to know for timeline reasons. I'm setting up the timeline for a young kingdom, and I want to know what would be a realistic time period between the moment the settlers find a good place to when they have finally built a succesful settlement using easily accesible resources. By succesful I mean a settlement that it's self-sufficient in resources. The resources are pretty much available as the kingdom encourages this expansion and there's multiple trade routes available. EDIT: Just for the future people asking this and finding this question. I am mostly curious about the time it would take for all the necessary infrastructure to be built. As in, how long would it take to BUILD a neighborhood of little huts, or a cobbled road, or a small wooden bridge. And mostly, I'm looking for a MINIMUM. Like, at least X time. [Answer] # How Much Money and Will do you Have? There are a vast number of variables in this question, but the simplest explanation is: As fast as you can spend the money. There must be actual valuable resources to be found in the area if it will be sustainable. People must WANT to live there or have no alternative. It must be able to sustain agriculture, and your society must have the technology to master the environment. There can't be effective and determined native resistance or such efforts are pointless. [Sebastos,](https://web.uvic.ca/%7Ejpoleson/ROMACONS/Caesarea2005.htm) or Caesarea by the Sea, was built by king Herod and the Romans to secure the region economically and politically. The Harbor, and most of the city, was built in relatively undeveloped territory with no existing harbor, and were built in about 12 years. To this day it is considered an engineering feat. To built a colony from scratch to operational city, this is about the minimum if you have essentially unlimited resources, manpower, a favorable location and will to do so. With less resources, building in an organic way, you'll have something more like the [Viking colonization of Greenland](https://icelandmag.is/article/what-happened-viking-settlement-greenland-new-research-shows-cooling-weather-not-a-factor). With the compelling demand for walrus ivory, the Norse moved into Greenland, at the peak having about 4000 inhabitants. While the timeline to "successful colony" is a little awkward to nail down, it was a growing thriving place within a century. But this illustrates the problem with establishing colonies. Within 400 years, the colonies were abandoned. Why? The central compelling trade item (ivory) dried up, but a successful colony would have survived at least at subsistence level. It has been suggested the Norse failed to adapt to local conditions and disregarded the native traditions that could have helped them. This theory is in dispute. The little ice age likely contributed to the Norse agriculture being unsustainable, as may the black death. Some people even suggested it was simply a place people didn't want to live, so they left. So at least a decade for a colony in a favorable spot with unlimited resources. Anything less, and you'll need will, a core resource to make it profitable, and sustained conditions to allow the colony to survive any of the frequent downturns that will strike such places on the edge of the civilized world. [Answer] There is no one size fits all answer to this question, location is going to play a huge part in the outcome here, not only in terms of available resources but also with regards to governmental investment in the success of the venture: * A settlement on good soil tucked away in a quiet temperate valley near the core of the kingdom far from strategic resources or turbulent borders has a short road to resource self-sufficiency. They'll be harvesting their own building materials (chiefly wood) immediately and have a crop in the ground by their second spring. However this settlement will be a low priority when it comes to prizing open the royal coffers and will receive little support or investment. * On the other hand a settlement on a strategically important trade route near a trouble spot may be in a poor position vis-à-vis locally grown food and other resources, but, because the the king is interested in security, gets supplied with a garrison, imported building materials, and paid artisans and labourers to put the core of the town to rights over the space of a few weeks one summer. It's location means the town can make it's living from road tolls etc... granted by royal charter with local production ramping up very slowly by comparison with the farmers in the first example. * On the third hand most new settlements in a medieval setting are going to be for the support of new resource extraction/processing sites because the best farming land will already be tenanted and the strategically important areas of the kingdom are already tightly secured. This means that new settlements are often planned towns sited where the availability of water power and/or confluences of raw materials make the establishment of timber mills, smelting works, and the like economically viable. These are settlements generally built with the backing of important local businessmen and land owners, they use as much local material as possible to keep costs low but they don't necessarily make any pretensions to self-sufficiency, instead they live by trading their ironwork, sawn timber, copper, or burned lime, for the necessities of life grown farther afield. [Answer] Each settlement has a different history and growth rate, and all of them are in the hands of luck. Just a few examples: I have been reading the history of the city where I live, and it all started with a small settlement on some sandy soil in the swampland left by the last ice age, nothing more fancy than a dozen of huts around a central square, around 1200 of the vulgar era. After about 100 years it was granted the title of city, which in those times meant "you are allowed to have your own weekly market", but it stayed nothing more than a spit on the map for other 400 years. Somebody thought it was smart to surround it with a moat and walls, but when they were destroyed in one of the many wars fought in those unstable years, nobody had the resources to rebuild them. And for the easily accessible resources? Well, local farmers used the patches of not so swampy soil to grow something, but trading and carrying good over long distances (more than 10 km) was an adventure, and when somebody wanted a paved road to be built, they had to fight the opposition of other villages who wanted the road to go closer to them, and invent some ingenious workaround to do it (since the city manufacturing the bricks for the paved road imposed a tax on their export, the buying city declared it to be needed for houses). Same happened with the building of canals and, later, railways. Then all of a sudden somebody founded a factory and the growth exploded. Or it can also go the other way around: take the city of Otranto, in the heel of Italy. In ancient times, thanks to its geographical position, was one of the natural bridges between West and East Mediterranean sea. It even hosted one of the first universities in middle age Europe. Then in 1480 it was [besieged and conquered by the Ottoman](https://en.wikipedia.org/wiki/Ottoman_invasion_of_Otranto), and few years later the discovery of the Americas shifted the traffics away, relegating it to be a small village. ]
[Question] [ If you have read Eragon, then you know of the Werecat: a race that can shapeshift between a 'large cat' and a 'child', almost certainly with no change in mass. The Magic System is based on the literal and the scientific, thus matter and material cannot be generated or removed without understanding how that could be possible. I'd like to take this concept and evolve it into what might be considered a 'Kitsune'. Rather, let's say someone magically evolved a werecat into a reflection of a 'Kitsune'. A Werefox for convenience, but not necessarily a race that is part-fox, just somewhat mirrorsing the theme. A mostly(or only) female race that could shift between a cat/fox-like animal with a long fluffy tail, a human with animal ear+tail features, and a human - but the mass has to be retained. Their evolution should require them to retain as small a figure as plausible, but be capable of safely 'mating with a human to produce children, which would need them to also have a pleasant appearance(if short?) to men in a medieval-type society. Probably closer to a physically attractive woman on a smaller scale in overall size rather than just being shorter? As a (probably unnecessary addendum) they would also prefer running (and probably walking) on their toes when in human form unless carrying significant weight(or would this be a lie?). Specifics can be changed if it doesn't fit realistically, but this is the general outline. The only magical component to this is the intrinsic ability to shapeshift between working forms. As they would exist in a medieval-type society, the Humans there would typically be malnourished and generally shorter, and they might naturally reflect that if needed. I would greatly appreciate numbers for both the werecat race and the custom race for comparison. Height: Human(-ears, +tail-mass), Hybrid(+ears, -tail-mass), Animal - also werecats too? Weight: how much (stays the same for each height) - also werecats too? I'm mostly looking for general height and weight, but details are appreciated. [Answer] let's run the numbers. A quick google search shows that the average fox in the UK weighs 9 and 17 lbs. Then according to a child weight percentage chart (also provided by google), your fox in human form will probably be, at most, the size of a 8 month child, assuming mass is conserved. If you assume that all your fox/people weight as much as the upper bound of red foxes (30 lbs) then your fox folk can be as large as a 3 year old child, when in human form. Or, and hear me out on this; unless your readers really like doing math and consulting statistical charts, you can just ignore conservation of mass altogether. You are already allowing for changing form, and you are saying that this is a fantasy race in a fantasy world. Skip the boring and science based limitations. Remember if your magic is sufficiently explained it ceases to be magic and becomes mundane technology. Magic is supposed to be the fantastic, by it's nature it breaks the rules of reality, don't ruin the fantasy and the wonder by binding it to what can be explained in our sciences. [Answer] The average human female weighs around 53 kg and is 159.5 cm. The largest fox species is the red fox, Vulpes vulpes. The largest recorded red fox in Great Britain was a 17.2 kg 140 cm long male. They are normally 90-105 cm long and 5-7 kg. A 53 kg fox would be around 198-206 cm long. A wolf sized fox is far out of the ordinary and would be very conspicuous. If we reduce the human form to 145 cm and make it underweight at 32.5 kg then it would be around 168-175 cm long in fox form, Perhaps less if the fox is exceptionally fat. The heaviest cat ever was 21.6 kg and 96.5 cm long. The longest cat ever was a 123 cm Maine Coon, which could have theoretically been 44.7 kg if extremely obese like the former cat, in which case it could be 161.3 cm tall in human form. If in human form it is only 32.5 kg and 145 cm like with the werefox, then it could either be an extremely obese 110.6 cm long cat or a moderately obese 123 cm cat. For either of these, they are going to be disturbingly large in animal form and very short in human form. [Answer] While the other answers make clear the significant difficulties involved in conservation of mass one potential approach is to include other changes. [Achondroplasia](https://en.m.wikipedia.org/wiki/Achondroplasia) > > Achondroplasia is a genetic disorder whose primary feature is dwarfism.[3](https://medicine.yale.edu/news/yale-medicine-magazine/unbreakable-bones-prompt-a-hunt-for-genes/) In those with the condition, the arms and legs are short, while the torso is typically of normal length.[3](https://medicine.yale.edu/news/yale-medicine-magazine/unbreakable-bones-prompt-a-hunt-for-genes/) Those affected have an average adult height of 131 centimetres (4 ft 4 in) for males and 123 centimetres (4 ft) for females. > > > This [chart](https://www.beyondachondroplasia.org/en/pages/47-health/health-guide/58-weight-for-age) puts the 10th percentile for 18 year old males at 25kg, and females at 35kg. You can use this as a starting point, to get your human form weight down further. Significant sensitivity while writing a character like this would be required. In the opposite direction for fox form, [unbreakable](https://medicine.yale.edu/news/yale-medicine-magazine/unbreakable-bones-prompt-a-hunt-for-genes/) bones have been observed in humans with up to 8 times the normal density, though I can't find any articles actually taking about the weight of the people involved or comparing that to others of their height and build. Given how far apart the initial weight requirements are, you'd still need some handwavium (additional really heavy tails?) to make this work. [Answer] If they are goo-like shapeshifters, who only assume a form on the outside (not muscles or other biological material) that goo can just get denser or rarer as the form demands. Otherwise... # Cheat, anatomically. Setting aside the fact that transforming from a human into a fox is so wildly physically impossible that "conservation of mass" is the least of your problems, remember, they're not real foxes or real people. So neither body has to be exactly like those of the corresponding species, only enough so to be convincing from the outside.1 Otherwise, since you're already deeply altering the internal organ structure to make room for more brain tissue, alter the organs even more. ## The gap Let's start with the baseline of: * A small and under-weight human, 4'10" and 35 kg, BMI 16.1 * An uncommonly large and powerfully built fox, 10kg in mass We need to bring that 35 number down, and that 10 number up. ## Bridging it Let's start by making the fox male. We're transforming back and forth between species, so transforming gender shouldn't be a problem, and gets us to the size of a very large male fox. Now, we're at 15kg for the fox, without even doing anything too weird! Next, let's change up the proportions a little. > > Foxes are also deceptively light canids; thanks in part to their very slender leg bones, they weigh about 30% less than you’d expect for a dog of their size. [(link)](https://www.wildlifeonline.me.uk/animals/article/red-fox-size) > > > Excellent. We're up to 19.5 kg. We can actually do the rest with bone density. * Give the fox form extra-dense bones. Bone mass proportion goes down as total mass goes down, but let's cheat and use the human numbers of 10-15% That gives us 2.5±0.5 kg of bone mass to start with. Terrestrial mammal bones are roughly 1g/cm in density. Whale bones go as high as 5 g/cm. Let's bump that up a notch to 6 g/cm,and make your entire skeleton out of bone that dense, which will add a rad 12.5 extra kilos. (if you were willing to make them out of steel, at 8~g/cm, you'd actually be done with room to spare). * Give the human form extra-rare bones. We'll reuse that 10-15% number, which gives us 4.375±0.875 kg of bone. Reduce bone density from 1 g/cm to 0.75 g/cm, and we get to drop the human's mass by a kilo! Now we're at a 34kg human (it's hard to lose weight, bro) and a 32.5kg fox. At this point, by fiddling around with some of the numbers, we can come up with something to close that 1.5kg gap, or just blame it on the tail. Or be cool as hell, and give your foxes steel bones. You're shapeshifting anyways, so why not? --- 1. You already have to do this to make the brain work, since fundamentally, human brains are vastly bigger than fox ones. Grey wolves, who are considerably bigger than foxes, have a brain 10x less in mass than a human brain. [Answer] Actual foxes weigh, at most (according to another answer), ~17kg (38lb). According to [the CDC](https://www.cdc.gov/ncbddd/actearly/pdf/growth-charts/323070-A_growthCharts_en_P.pdf), that's roughly a 4½- to 5-year-old child, or ~110cm (43in). A more realistic "typical" number is probably 12kg (26lb), equivalent to a 2-year-old, ~90cm (35in). That's actually not entirely implausible for a meaningful character, but they're going to have a lot of difficulties interacting with "mundane" humans due to their perceived age. Paolini's "large cats", equivalent to "children", might well have had animal forms closer to a [Eurasian lynx](https://en.wikipedia.org/wiki/Eurasian_lynx). At ~20kg (44lb), such a cat would have a human form closer to that of a 6-year-old, about ~115cm (45in) tall. They would definitely seem like "children", but they'd have a much easier time than the toddler-sized shifter you get using a realistic mass for a fox. That said... what constitutes a "fox"? If you're looking for something that looks the part, but is allowed to be larger in animal form (more like Paolini's werecats)... have you considered the [maned wolf](https://en.wikipedia.org/wiki/Maned_wolf)? [![maned wolf](https://upload.wikimedia.org/wikipedia/commons/thumb/9/9c/Chrysocyon.brachyurus.jpg/211px-Chrysocyon.brachyurus.jpg)](https://en.wikipedia.org/wiki/File:Chrysocyon.brachyurus.jpg) These beautiful animals look a lot like foxes, except in size, with an adult weight range of about 20-30kg (44-66lb). A human child of similar weight would be between 6 and 9 years old with a height range of about 115-135cm (45-53in). It wouldn't be too unbelievable to stretch that a bit and have your characters be roughly equivalent to children in their early (pre-pubescent) teens. (Except your females are going to be, ah, "fully developed". That's likely to make for some interesting reactions from "mundane" humans.) For that matter, you transplant the maned wolf's colors onto a [Eurasian wolf](https://en.wikipedia.org/wiki/Eurasian_wolf), for which particularly large specimens can reach almost 80kg, which is easily within the realm of weight for a normal adult human male. So, in short, if you want your fox-people to be fox-sized, they're going to have to be really small humans. If you're willing to let them be more wolf-sized, they can be much larger as humans while still looking like relatively "normal" animals. --- Note that all numbers are taken from the mean curve; actual correspondence between age and weight/height can vary considerably, but since we're talking about adults that look like children, that variation isn't all that meaningful for our purposes. The weight/height correspondences are less variable. ]
[Question] [ I enjoy playing [FTL: Faster Than Light](https://en.wikipedia.org/wiki/FTL:_Faster_Than_Light) and got inspired to write my own but more sophisticated 2D strategy game with the focus on custom ship construction. I want to have many systems on board which will require lots of engineering rooms. For this it would make sense to have multiple floors for housing all these systems and machines, but that would make ships three dimensional which would greatly overcomplicate an already ambitious game. To keep the scope manageable, ships must have only one floor, but what reasoning do I give to the player as to why ships can only be flat? [Answer] # Smaller target But not to enemies. When flying at relativistic speeds, even the smallest impact with space debris can ruin your day. Hitting an asteroid at 0.9c is equivalent to being hit by an asteroid coming at you at 0.9c. In order to minimize damage, ships should ever have an expletive big shield attached to their tip, and/or present the smallest surface possible when coming at something. Making the ship as flat as possible helps with the latter. [Answer] # The ship can be 3D, so long as your representation is 2D The easiest way to do this is with an abstract node-map, but with some clever ship design, you can have the inaccessible areas of your ship overlap with the crew-accessible parts and this have your crew climbing ladders, sliding down grav-lifts, or going through corridors/jeffrey tubes that squeeze between inaccessible sections. You could also use your game perspective to enhance this, an isometric or 45° camera angle gives you some opportunity for viewing the z-axis in a way that FTL's bird's-eye view doesn't allow you to. [Answer] Artificial gravity In order to deal with an unrealistic, artificial restriction, explain it with an unrealistic, artificial technology that is ubiquitous in science fiction. 99% of TV / movie portrayals of fictional spaceships have artificial gravity on board, because it's just too expensive to simulate zero G on film. (Although there's a feature film being shot in orbit soon...) The large majority of science fiction books also have artificial gravity, because it's generally accepted by audiences and less risky than trying to go hard sci-fi but then messing up the realities of zero-G life. So, assume that your spaceship also has artificial gravity. Next, specify that the grav plates that create the artificial gravity: 1. do not have the gravity diminish in proportion to the square of the distance from the plate, but instead 2. perfectly simulate 1G within 3 metres\* above the plate but suddenly drop to zero G at a greater distance; and 3. plates next to each other do not interfere, but a plate operating above another plate causes catastrophic gravitational effects. \If you really need a higher ceiling to allow vehicles or (shudder) mechs then you can stretch it to 4m, assuming average-height modern humans, but that height could be split into two levels if there was a shortage of space. Hence, the occupied part of the ship is at 1G and must be all on one level. There may be fuel tankage occupying other levels, but there is no ability or reason for the crew (or other players) to go there. [Answer] The ship is huge, the living space is not. Most of the ships volume in consumed by futuristic FTL drive, fuel tanks, reaction mass, and artificial gravity generators. Only a small portion of the hull is crew space. This is not even unreasonable, look at a modern space ship, tiny little living capsule, absolutely massive fuel tank and engines. [Answer] Daleks* Everyone knows Daleks can't climb stairs, and thus build single level spaceships. [![enter image description here](https://i.stack.imgur.com/fBDWe.jpg)](https://i.stack.imgur.com/fBDWe.jpg) [Answer] The ship is actually 3 dimensional, but the builders have advanced short-range transporter tech. Instead of climbing stairs or a ladder, or using an elevator, crewmembers simply walk into the transporter portals, which techno-magically place them on different levels. Thus even though the ship is 3D, to anyone inside, all the different levels map to a 2D space. ]
[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/194612/edit). Closed 2 years ago. [Improve this question](/posts/194612/edit) So I have this 3-2 1/2 feet tall humanoid species called Pinokiins that as of the time of typing have 3 fingers(thumb included) and toes on their hands and feet instead of 5. Is this a negative thing? Could they still have as much dexterity as humans? Could they play the same instruments as we do and as good? Could they make detailed drawings and paintings like us? Could they still have the same grip as us? They tend to go on all 4s when they run or travel long distances on foot as they have arms as long as their legs and are hunched over alot, so would having 12 digits in-all instead of 20 make this difficult to do? [Answer] Three fingers can produce all the [necessary grips](https://www.semanticscholar.org/paper/A-comprehensive-grasp-taxonomy-Feix-Pawlik/ff6edd2fde1d38a01294c974611355b34e99a0dd) the only one that really suffers is the clutch grip, (AKA ball grip, AKA sphere grip, AKA ect. grip), but it still works it is just not as good, and almost half of the other possible hand grips only use three fingers anyway. A lot of the most important tasks (like stone knapping) depend more on the wrist than the fingers. [![enter image description here](https://i.stack.imgur.com/AIIBK.png)](https://i.stack.imgur.com/AIIBK.png) Grip strength depends on the muscles on the arm not the number of fingers, three fingers may actually end up being stronger since you can have thicker finger bones and tendons in the same area. [Answer] A hand with three fingers is just about the minimum needed for the tasks humans use our hands for. I was once informed by a historical reenactor that early modern armies mandated that their soldiers have at least three functional digits per hand. (Recruiting standards back then were lower, to say the least.) Tools, musical instruments, et cetera would need to be designed a bit differently to accommodate a non-human hand structure. Playing a harp, for example, or typing on a keyboard would be harder with fewer fingers. If these creatures walk on their hands, they likely have a gorilla-like body plan. Knuckle-walking evolved [multiple](https://en.wikipedia.org/wiki/Chalicotherium) [times](https://en.wikipedia.org/wiki/Megatherium) in Earth's history, as it's the easiest way to have a foot that works both as a load-bearing element and a hand. ]
[Question] [ If I have a group of humans that were genetically altered in a similar way, but with different expression of effects in the individual (for example changed eyes, tail growth, wings, scaled skins, possibly other organs non-existent in regular humans...): 1. would that group be able to breed naturally amongst each other and have fertile children? 2. would they be able to breed with "regular" humans? 3. If the answer to (2.) is "yes", how likely is it that the offsprings would be fertile? 4. If the answer to (2.) is "no", what type of changes would be reasonable in the manipulated humans to result in fertile hybrid offsprings? [Answer] *If you want it to, then yes. Otherwise, probably not* If you're genetically engineering people to be radically different than humans, you probably aren't trying to create things what will spread through your general population. If I were making monsters (and I have, in stories) I would either design them so they specifically could or specifically couldn't interbreed, depending on my desires. If you left it up to chance, you'd either get non-viable offspring or sterile mules who may or may not have functional parts. * Trying to create super-soldiers? Maybe a master race? You don't want those genes running rampant. Make your alterations to rearrange the genes on the chromosomes, so your resulting gene combinations look more like humans trying to interbreed with goats - not going to happen. * Trying to hybridize humanity with your alien species? Well, then, make a CRISPR-like system where extra DNA is made for this scenario. Have gene sequences tha overwrite human ones, so the key genes are passed on. Have an extra chromosome with sequences that specifically cause it to make an extra copy in any cell with only one. If either parent has the extra DNA, it's passed on to the descendants. [Answer] The answer has to be "perhaps". Some traits, like eye-colour, are the result of a single gene, there is one strand of DNA that controls eye colour. If you have a functioning copy of that gene you get brown eyes, if no you get blue eyes. (actually, this might not be literally true but it is a reasonable approximation) Many other traits would be a combination of many genes. For example, a tail would not be a single piece of DNA, there would be multiple genes that could affect the length, shape, musculature and so on. If a tailed person had children with an untailed person, the child would get half of those genes, and the effects of only having half the genes to make a tail might be unpredictable. Probably you'd get a stumpy short tail, but in the worse case you get the tail genes doing something bad, like lengthening the spine or even something which seems utterly unrelated to tails. For example a gene might cause the vertebrae in the coccyx not to fuse, but it also causes the skull to thicken which compresses the brain and kills the fetus. So a second gene is used to turn off the "skull thickening effect. But that second gene, on its own also prevents the head from forming (and the embryo dies very early) You need to have both genes, or neither, and this is a simple "only two genes involved" In real life, even eye colour is controlled by 8 genes, many of which have side effects (or the eye colour is a side effect of the gene) Wings, for example would require massive gene editing. I would not like to be the child of a winged and unwinged human. [Answer] Yeah, I'll go with "probably not". Different eye, skin and hair color are no big deal, it already happens. The other traits however are a lot different. Let me explain you briefly about genetics and natural hybrids: the absolute majority of animals on earth works on a paired system, in which each animal has a number of chromosome pairs which make up their genome and allow them to function. Upon reproduction, it's gametes have these pairs separated, so that once it meets the other gamete, each half of a pair meets, allowing for a new animal of that species to be born. But if most animals work on paired chromosomes, why don't we see a dog and a chicken in the farm giving birth to a tiny griffin? Because a trait that defines a species is reproductive isolation, meaning that:if 2 species can naturally breed among them in the wild and generate viable offspring with no issues, they're likely not 2 different species. Now why did I talk about that? Because we need that to talk about your humans: eye color is a relatively small thing that's controlled by a small number of genes. That is why people with different eye color can have kids with no problems. However, traits like scaly skin (a reptilian trait that'd also, most likely, involve the absence of glands in the skin), wings on the back (not only its an extra par of limbs [I'll not discuss the functionality of these limbs], it's a modified pair of limbs with adaptations vastly different from the body) tails (might be the least drastic here, since we did have tails at some point in evolution... Oh wait, it's a fox tail, isn't it?) and other organs normal humans would normally lack (in the best of cases would require special adaptations to be ribcage to be able to contain these organs) are all traits that require a series of genes, and the very existence of each of these traits would require the presence of secondary adaptations of the body to be able to function, from modification of the existent muscles and bones to the addition of new ones to other alterations that might not be noticeable at first. What I mean is that such complex traits, along with their secondary alterations regarding a common human, would most likely require new chromosome pairs altogether. These guys will most likely have more than 46 chromosomes, and the new ones will most likely express traits which negate the expression of normal human traits. But without the other half, these chromosomes won't be able to express properly, thus resulting in normal humans at best and result in several issues regarding malformation and sever health issues which make their survival essentially impossible at worse. The only way I can see them reproducing with one another without major issues is: having additional chromosomes which completely control these new traits and which usually remain completely inactive without their pairs, while expressing themselves while inhibiting other normal traits in favor of their own when found in pairs (essentially entire chromosomes being [recessively epistatic](https://study.com/academy/lesson/recessive-epistasis-definition-examples-causes.html)). Note that I'm not a biologist or a genetic specialist, so I can't say with absolute certainty that such a process could work, but to move it does seem in a way to partially solve your issue regarding reproduction (we're already using handwavium to have humans with reptile traits and new organs, so why not?). So summing up: can these altered humans breed among themselves as well as with normal humans? Realistically no, but if you alter their genome so that all of the changes are causes by new chromosomes that remain inactive when not paired could somewhat circumvent unwanted side effects of such relations. Note however that, having an uneven pair of chromosomes, unless the new one somehow migrate on their own, during meiosis, to one of the resulting gametes, these hybrid children will be infertile (mules are also infertile due to having an uneven number of chromosomes) at best and, should the new single chromosomes try to express themselves, result in malformed fetuses which likely cannot survive more than a few hours after birth in a worst case scenario. [Answer] # Its carries risks To quickly answer your questions before going into the details: > > 1. would that group be able to breed naturally amongst each other and have fertile children? > > > Only for if each form of genetic engineering is on a different chromosome. > > 2. would they be able to breed with "regular" humans? > > > Only if the genetic engineering is isolate to a single chromosome > > 3. If the answer to (2.) is "yes", how likely is it that the offsprings would be fertile? > > > In a perfect world, 50% chance of genetically altered and 50% chance of normal per trait For the purposes of this I am going to keep this focused on one example: a genetic alteration giving wings. I will refer to it as the wings gene and have the wings gene traits all be dominant by default. As for whether or not they will be capable of generating enough lift is a [totally separate question](https://worldbuilding.stackexchange.com/questions/152301/would-this-winged-human-angel-be-able-to-fly) which I will not cover. ## Chromosomes Humans genes are organized into 23 chromosomes that come in pairs. When breeding one of each pair is randomly selected to be passed on to the child from each parent. As such for this wings gene it needs to not only add wings to the human, it needs to modify the existing bone structure on the back of the human for the wings to lock in, greatly increase the human pectoral muscles (and modify them so they can be linked to the wings), and modify the human to be as light as possible. That is a lot of modifications, and if they are spread out and directly integrated into the respective chromosomes that govern those aspects of the body then it will not be as complex and thus reduce the chance of the alteration indirectly harming the individual. However if that person was to breed with a normal human the resulting hybrid child might end up with oversized pectoral muscles and no wings, be normal weight and not able to generate enough lift, or could be missing part of the bone modification to the back resulting in the shoulder sockets becoming mutilated. None of these are desirable. As such all these modifications would need to be on a single chromosome so that it will be all or nothing. Since you cannot directly tweak the existing dna on the other chromosomes, you will be having to add additional DNA that suppresses the normal behavior and development of the body that is present on the other chromosomes, much like how the Y chromosome suppresses the development of mammary glands in males (most of the time, and it does not stop the formation of the nipples). That is a lot of extra DNA and the problem is fitting it all on one gene. There are two options for this: ### Option 1 Have one copy have a normal chromosome paired with a wing gene chromosome (similar to how the X and Y chromosome work). This has the benefit of keeping the total amount of dna in the cell roughly the same. The problem is that it would behave like the Y and X chromosomes do without the safe guard that they have (two males cannot breed together and thus cannot result in a YY pair). This is bad since a genetically altered person could only safely breed with a normal person to ensure that they get the normal gene that can be paired with the winged gene. If two people with the wings gene were to try and have a kid there would be a 25% chance of the fetus having two wings gene which would be fatal or carry severe disorders. ### Option 2 Keep the normal DNA and add all the wings gene DNA to it. Thus if they have two copies of the normal + wing DNA they are still good. So anyone with the alteration can safely breed with anyone who has it or anyone who does not have it. If a hybrid was to breed they would have a 50% chance of passing the wings gene along (and two hybrids would have a 75%). Sadly though, this carries its own problems. The size of the nuclei in the cell is not changing, but now there is more DNA in it. This will increase the chance of something going wrong during cell division. This can possibly lead to health issues, with the worst cases being cancerous cell growths. If this happens early on in a pregnancy or with the sperm or egg then it will likely result in a miscarriage or severe birth defect. There are [lists of various genetic disorders](https://en.wikipedia.org/wiki/List_of_genetic_disorders) that can be found so I will not go into what they are. These lists do help with world building too, if the wings gene happens to be on chromosome 5 then does it increase or decrease the chance of [Cri du chat syndrome](https://en.wikipedia.org/wiki/Cri_du_chat_syndrome)? How much of a chance these problems have of going up I cannot say, but since this is your world you can decide how much of a factor you want it to be. ## Conclusion As such I recommend for it to be believable and get what you want, each alteration is coded onto a different chromosome and preserves all the normal DNA on said chromosome. Any genetically modified human might have these cool amazing traits, but they also are more prone to cancerous growths, miscarriages, birth defects, and genetic disorders. ]
[Question] [ All my ideas are really far fetched fantastical, way stranger than one would be used too, crazy unrealistic with its magic, and I worry about the accessibility of these worlds to an audience. Is anything, no matter how far fetched, fair game as long as its self consistent? [Answer] The story should be relevant to us as people, it's setting could be as wild as you want (wilder the better) as long as it's self consistent as you say. The key in your question in my view is 'self-consistent'. You could create a world out of a single idea and this leads you to unforeseen results. The story then comes out of this setting, and as long as its implications are relevant to us as people, it will not alienate the audience even if it is totally wild. Vernor Vinge, in his Across Realtime stories, had a simple idea: The ability to create bobble universes that isolates an area into a spherical separate universe where time is frozen until it pops. Using this, he created a whole plethora of implications in his world, where humanity fragments through time as bobbled cities burst millions of years later, and people bobble their way through the galaxy. But coupled with this is the story of humans and their unique qualities coping with this reality. Or his Deepness in the Sky series, which are based on a simple premise that computers are slower and 'dumber' in the middle of galaxies, but ultra-smart at the rim, and god-like outside. This allowed him to create world of conflict and discovery throughout, coupled with survival stories of humans trying to hold onto their identity within it. Go forth, and find the implications of your craziness. The best stories come from finding where the boundaries are, what the end points could be, and what our place is between them. [Answer] There is a reason why one of the commonly cited pieces of advice to authors is murder your darlings. I know it can feel irritating to feel like you're throwing away work, but while it can be extremely fun to think about interesting worldbuilding, it never sells a story on its own. You should also include less of what you use than you think. As a writer, worldbuilding is homework, and homework exists to make the difficult look easy. A really nice analogy I'm stealing from Mythcreants is that you can think of your story as having a budget of a stack of 36 pennies(similar to the point about economy of innovation). This has to be divided into focusing on plot, characters, theme, and explaining your worldbuilding. So a complicated mystery works better in a modern setting with a relatively uncomplicated detective because it leaves more time dedicated to the mystery itself. Here is where your unusual premise becomes a problem. The more unusual it is, and the more different ideas you explore, the more of these pennies you'll have to spend explaining it. This means you'll have less to spend on things like character, plot, and theme. Novelty of an unusual premise helps a bit to sell it, but rarely enough to make up for this loss. People, especially general audiences, don't read books or watch movies for cool worldbuilding alone. They enjoy stories because of the characters in them and the journeys those characters go on. As much as I love cool worldbuilding and exploration of ideas in works like Ghost in the Shell, The Expanse, or The Legend of Korra, if I didn't enjoy the adventures of Motoko, Amos, or Korra none of that would matter. [Answer] For every published story there are probably a dozen authors with the same story who spent 20 years worldbuilding instead of actually writing but we’ll never get to hear their names because they’re still too busy fantasising over maps and characters backstories (I love drawing maps!!!). Be brave, bite the bullet, start writing. Only then will you know. [Answer] Ground your weird with the familiar. @JustSnilloc - has a good example with Wonderland; it is trippy and surreal, but the reader is grounded by Alice and her ordinary perceptions and reactions. [Riddley Walker](https://en.wikipedia.org/wiki/Riddley_Walker) is written in a very difficult future patois but the world it describes is not that bizarre. Kafka's Metamorphosis has one super weird element, and the rest of the world is built around and shaped by that weirdness. A very strange musical piece with dissonant and jarring chords and tones can be grounded by a familiar time signature and beat. Give your reader or player a place to stand that is familiar, from which to survey and appreciate your high weirdness. Even the familiar can be unsettling and different when illuminated by the weird and novel. [Answer] Decide who you're writing for. There is an old saying: write the kinds of stories you like to read. If you like far-fetched and fantastical, the strange beyond the wildest imagination, that that is what you should write and that is how you should worldbuild. A world does not have to be consistent within itself, though whether or no, it should be well made and enticing for others to enter and discover what is to be found. This is called art. There is another old saying: I like to eat. If writing is your primary occupation and your primary source of income, then chances are you will be working with editors and publishers and will have in stead to "write to the audience". This is called business. If you're in this forum, chances are good you worldbuild and write for fun. My advice would be nothing more than to make the worlds you like to imagine and write the stories you like to read! Your audience will fine you! ]
[Question] [ We are in a far future setting where humans (or transhumans I should say) achieved two things: 1. be able to modify themselves genetically to the point where they can have completely different organs to what we have now 2. be able to customize the earths atmosphere to their needs without causing unwanted side effects (like global warming) The goal is now that nobody has to eat anymore in the way we do now and the plan is to get the necessary nutrients from breathing the customized atmosphere. This can either work by having nutrients directly in the air or the components are in the air so when the transhumans breathe, their new and specialized organs can produce any necessary nutrient. Removing the necessity to drink is not a priority. If they can get their water supply from their atmosphere it is a nice bonus but if they drink it like we do now it is also okay. My question is: Can this be possible given the two assumptions above? --- There are a few potential problems I can think of with this method of nutrient supply: * breathing may not be efficient enough * the constant access to food may be a problem * the needs for nutrients vary too much to have one atmosphere composition that works for anyone anywhere anytime * the air would be so heavy that it would get too dense in low altitudes or that only people living in low altitudes would have access to food * other organsims may reproduce incredibly fast in this nutrient rich atmosphere [Answer] ## The current atmosphere is just fine As you're aware, plants are mostly carbon, and they get it entirely from carbon dioxide in the atmosphere. They get extra nutrients from the soil, but in much lower quantity. Since you allow drinking, you should be able to enrich the water with all the minerals needed. Clearly trees exist, so the mechanism for converting carbon dioxide and minerals to organic matter is out there. The only problem is it requires huge amounts of energy, so trees need a huge surface area for photosynthesis. If you can replace photosynthesis with [wireless power](https://en.wikipedia.org/wiki/Wireless_power_transfer), you're all good. You'd need a huge network of power plants, which we already have. Additionally you want power transmitting antennas all around the world. We sort-of have this capability with mobile networks, but it's incomplete and they don't send enough power. But this should be a doable engineering feat if we chose to do it. Finally you need a custom organ that includes a giant coil to efficiently capture power. Once you have the energy you need an equivalent to photosynthesis to go from electric energy to organic compounds. And that's about it. Final note is that our current breathing rate should also be sufficient. When you lose weight you are literally burning fat, with the exhaust CO2 going through your blood and out of your lungs. All the weight you lose goes through your lungs or the water you pee. Thus the throughput of CO2 going through your blood and out the lungs should also work in reverse and let you grow at about the same rate as losing weight. [Answer] While possible, I don't think that a society of transhumanists would do what you're proposing as it would be a massive waste of resources. Saturating the entire atmosphere with enough "nutrients" to make it practical for transhumans to use would be a colossal effort and probably completely destroy all native ecosystems. Most air never gets inhaled by humans anyways since the vast majority of "air cycling" on Earth is done by plants. If you want to eliminate the need for transhumans to eat regularly, then maybe only make them take supplements while they're growing of if they need to repair themselves. For energy needs, batteries along with wireless charging could be the solution or people could grow nuclear reactors inside themselves and swallow a vial of tritium every couple decades or so. Additionally, I think that any society of transhumanists would be rather diverse with different people choosing different upgrades or enhancements. It's possible that people would need highly customized or specialized diets for their specific body parts and adapting a one-size-fits-all solution might not be the right call. [Answer] This will be a massive undertaking, and is probably not economically viable enough. As other answers pointed out, saturation the entire atmosphere with nutrients is near impossible, and a gigantic inefficient waste. But even if it can be done, this will not negate the need for food production, as the nutrients will still need to come from somewhere. This will also need to be taken over by a sitting government entirely, the production as well as the distribution, as this is not really an opt-in kind of situation. Either everyone will need to do it, or nobody can. So not only will you need a gargantuan amount of resources, you will also need to unify the earth under a communist regime. As plenty of examples have shown us, communism doesn't always work the best, because of human nature. If you genetically modify humans, their mentality is where you would need to start. On top of all this, there is the cost of genetically modifying humans. This can't be done to just a few humans, as they will need to effectively repopulate the earth. That is if their gene modding doesn't have any averse effect on human physique to begin with, especially their reproductive ability. And if the modified gene is carried on through reproduction to begin with. Forced evolution like that will not be easy. You could offset it by only allowing this in enclosed spaces, perhaps as large as (domed) cities. But this will still be a huge undertaking nonetheless. And anyone not living in the city (or travelling) will not have access to food, as all of it is used to supply the cities. All in all the convenience of food consumption is unlikely to ever be so big an issue that it will need a solution like this. [Answer] <https://en.wikipedia.org/wiki/Radiosynthesis_(metabolism)> - "eat" PU238 once every 20 years or so, the stomach equivalent produces melanin which, in its activated metastable form, is circulated by the blood stream to carry the necessary energy into the cells. Biochemistry is no longer needed as a source of energy, all the other supporting processes are tuned to maintain the brain and reproductive organs. Like photosynthesis, except at higher energy levels and not limited by the surface of skin that can see the sunlight. [Answer] # They’d be filter feeders that eat highly dense pollen. The transhumans you describe sound very much like the [Astomi](https://www.orionsarm.com/eg-article/47e9ab1b4d5a7) from Orion’s Arm. They’re filter feeders who live in specialised space habitats that include plants that produce large amounts of pollen that they feed upon. They do this by using a layer of fine hairs that cover their bodies that collect an amount of pollen before retracting under the skin so that the pollen can be digested before extruding again. Since the human body doesn’t have enough surface area to make this a viable feeding strategy on its own, they supplement this with a symbiotic “flower” implant on their backs that greatly increases the surface area available for them to feed with. [Answer] Have you thought about making these humanoids undergo [photosynthesis](https://en.wikipedia.org/wiki/Photosynthesis)? That way, they can get many of their nutrients without even the need for air, just sunlight. I'm no biologist, but it seems like your people would then only require water and the air we know. Furthermore, it seems like your second point counters any issues that might arise. EDIT: As you pointed out to me, photosynthesis does not provide enough energy to sustain a human, so that possibility flies out the window. To answer your question, though: It seems like your two stated facts, that these transhumans can pretty much adapt themselves to any environment and that you handwave the risks of pumping the air full of nutrients, this idea should work. This constant access to food might be unhealthy to individuals who require less energy, like children, so keep that in mind. So: It works, you just gotta make it believable. [Answer] This is not realistically possible, unless your transhumanism includes serious cybernetics, in which case "breathing" would stop being a thing anyway. The vast majority of the food you digest serves as fuel. Your body reacts this fuel with an oxidizer taken from the air to provide the energy you need to survive and maintain the high activity of an animal. If your "solution" is to mix this fuel into the air at densities sufficient to support human activity, then you have a reactive fuel-air mix that would ignite and potentially kill everything in the world at the first lightning-strike, or if someone lit a match in the open. If your "solution" is to remove the oxidizer from the air, then you've simply switched from eating fuel to eating oxidizer, which requires even more biological changes, as our carbon-based systems are not designed to chow down on solid / liquid oxidizers. If your solution is to forgo the fuel entirely and switch to photosynthesis, you don't get enough energy. There's a reason plants are virtually inactive. You need roughly 8MJ (2000 food Calories, which is actually 2,000,000 calories) per 24-hour period to survive. Sunlight averages roughly 160 Watts per square meter over the course of a day, which translates to 14MJ per square meter per 24-hour period. If you can capture sunlight with 100% efficiency, you need to have a cross-section of 0.6 square meters exposed to the sun throughout the day. Photosynthesis only captures 6% of the sun's energy (it's 60% efficient within the wavelengths it absorbs.) so you would need 10 square meters exposed to the sun throughout the daytime to capture enough to survive on chlorophyll. Photoelectric panels are 20% efficient, and have a theortic maximum of 33% efficiency. If you powered your transhumans with maximum efficiency solar panels, they'd need to average 1.6 square meters of skin facing the sun throughout the day. The entire body of a healthy adult has approximately 2 square meters of skin, which translates to less than 1 square meter that can be faced in any one direction. To make this work your transhumans would need large bat wings made out of photoelectric materials (and some efficient way of converting electrical energy into biological energy), and would have to lie with them spread out toward the sun throughout the day time. (So, it might be possible, but everyone would have to ask whether it was realistically worthwhile.) If your solution its to replace all the messy bits with metal and power yourself with electricity, then there's not much point in breathing (other than using air for cooling). ]
[Question] [ I am Howard Lovecraft, a mediocre science fiction writer who has discovered an ancient text called the Necromonion. This text was written by Eldritch dieties and causes irrevocable insanity in all humans who lay eyes on it. I have decided to spread this manuscript to millions of people around the world in order to cause chaos and destruction across the human race. The reason? Some men just want to watch the world burn. People don't read books anymore, so I have determined that the fastest way to spread this manuscript is through the internet by use of social media. Websites such as YouTube, Facebook, Twitter, etc, have connected people all across the world and allow them to keep in touch with each other. People who you knew in high school and no longer care about can now be updated about your current life. By uploading the Necromonion to my personal page, it can now reach others much more quickly and efficiently. There is a problem however. The thing that causes the manuscript to be so effective at causing insanity also Stops it from reaching as many people as possible. When it's effects are discovered, my page can easily be blocked or removed, limiting it's availability. Worse yet, there is so much information on the internet aimed at grabbing people's attention. From cat videos, to memes, to political outrages, the media scene has become so over-saturated. I need to be able to affect as many people as possible with the Necromonion by overcoming these hurdles. How can I accomplish this? [Answer] # Impact and Speed are not the same goal If your goal is to maximize the spread your message, the overall fastest way is not necessarily the most effective way. As you note, once the existence of the [Yellow Note](https://en.wikipedia.org/wiki/The_King_in_Yellow) (as opposed to brown note) becomes a matter of common knowledge, the authorities will jump immediately to contain it. So what you actually want is a technique where you can prepare, possibly for a great length of time, in secret, and then have a huge impact all at once. It might not be 'fast', but there are things you can do with wider reach than the Internet. # Hijack the mass media It's [easier](https://en.wikipedia.org/wiki/Max_Headroom_broadcast_signal_intrusion) than you think to [subvert](https://en.wikipedia.org/wiki/Broadcast_signal_intrusion#Cable_network_feed_intrusions) mass media. Technically, there aren't really all that many protections in place to prevent it, and if you find the right spot, it's relatively easy to have a large impact. The [Captain Midnight](https://en.wikipedia.org/wiki/Captain_Midnight_broadcast_signal_intrusion) intrusion hijacked HBO for a large portion of the United States. The reason these incidents aren't more common is afterwards, immense effort is spent investigating them and tracking down perpetrators. But you don't care about any of that. You just need a video of someone reading from the Pages in Yellow broadcasting for a few minutes. So, since you don't care what comes next, hit the books and learn to be a good enough hacker to ... # Hijack the Emergency Broadcast System [Actually happened a few years ago.](https://arstechnica.com/information-technology/2013/02/bogus-zombie-apocolypse-warnings-undermine-us-emergency-alert-system/) By the time the authorities can get your signal shut down, it's already too late. The feds administer the system, so its security is awful (like most of the rest of their security). None of the weaknesses outlined [here](https://arstechnica.com/information-technology/2013/07/we-interrupt-this-program-to-warn-the-emergency-alert-system-is-hackable/) have probably been addressed. # The 'S' in 'IoT' Is For Security Movies and books like to give the impression that hacking things is hard. The reality is being secure is hard, and the United States couldn't even keep the plans for nuclear weapons secure by physically sequestering everyone working on it in the desert. Security is in general [pretty awful](https://www.youtube.com/watch?v=rnmcRTnTNC8). In 2003 a guy broke into Windsor Castle and walked right up to the VIPs there for Prince William's birthday. [He climbed one wall, then just acted like he belonged there.](https://en.wikipedia.org/wiki/Aaron_Barschak) You might think it would be hard to hijack the Emergency Broadcast System. It's not as hard as you think. [Answer] Buy ads. It is implausible that ads would drive people insane,\* so you'll probably reach a bunch of people before anyone figures this out. You can buy targeted ads to reach out to people who will be less missed at first, and geolocated ads if you want to see if you can take out a small town or whatever. Serve up inoffensive content at first. Get a following (may be tricky if you are truly mediocre). Then flip on the madness. This might get you caught. Just laying eyes on it drives people nuts? Put up a few copies in the middle of Times Square. You may need accomplices to hold them up on posterboards, like a protest. Then toss a bunch of puppies off a tall building right next to them. You'll madden a ton of people just because Times Square, plus the news will probably broadcast this across the globe. You will most likely get caught. Maybe try to get it up on a livestream (although doing so without driving yourself mad may be tricky). \*Well, to some extent they already seem to, but not in the manner you are discussing. [Answer] You have the same problem that viruses have, you want to infect hosts, make them infectious to others, but otherwise remain undetected. Then (less like a virus) you want to release the destructive payload in a centrally coordinated way. The added challenge here is that the final exposure requires reading a book rather than a simple sentence. This takes some investment of time and you want to time things so that most people make that investment at roughly the same moment. # A computer game A computer game is an artifact that you can share in viral fashion, but still control centrally to release the Necromicon at a predetermined time. It also has the added benefit that you can create a fictional world where a Necronomicon is an entirely plausible artifact, no matter how macabre it looks. In the first stage you just create a game that is as addictive as you can make it. Pull out all the stops, make it a cross between World of Warcraft, Farmville, Candy Crush and Clash of Clans. Ensure that people post about their progress to social media, or about the cool stuff they've found in this new game universe. Maybe develop a few different games, so that you can hit different markets. Give the games an immersive environment with some mystery, and crucially, center everything around mystery books. Players find mystery books and read them to unlock new content and find hints to the puzzles that have been bugging them (a bit like the journals in the Myst series). From day one, give hints about the ultimate book, the Necronomicon, which will provide the clues required to unlock the central tomb. Release new content periodically. Spread a rumour that there's a big update coming that will feature the Necromicon. Include it as a locked book, with a special code, to be found at a particular time and a particular place. Everybody gets the code at the same moment, starts reading at the same moment, and the world burns. [Answer] I think the most effective way to spread the text is a three or more fold approach. The first approach is to take a page from the flat earth playbook. Spread rumors and memes that simultaneously declare the existence of the text a hoax and that it contains the absolute truth of the universe. This step is to get the phrasing and words into the global consciousness. You can see how successful it was for the flat-earthers so it will work for Hastur too. The second step is to construct a vast internet path to the actual text. The real text should be deep in the dark web. With many sites containing fragmentary pieces of the actual text mixed with fraudulent contributions. The maze of paths to this site requires the hunters to shift their way through a complex web of internet clues to guide them to the eventual site. In this step, you are using our all too human allure of the difficult and forbidden to compel people to infect themselves with madness. They'll believe they are either debunking the idea of searching for ultimate truth, but they'll keep at it the way humans have also sought to scratch niggle-some itches in their psyches. The third step is to get governments, professional associations, the PTA, FDA, KGB, Mossad, anyone you can, to declare that it doesn't exist and that no one should try to find it, its dangerous. Fourth and following steps all pretty much the same thing over and over. Get celebrities to comment about it -- how stupid it is, how sexy it is from someone to look for it, how smart people don't look for it, how smart people are looking for it Embedded it in advertising campaigns, Have Nancy Reagan style just don't look for its campaigns. This step keeps it in the global zeitgeist and, inevitably, one of the different approaches will be attractive to someone and they'll look for it. The whole of social media influencers, sensing the opportunity to make a buck, or get famous, will lend their voices to search and sharing clues. Soon the entire world will be hunting sharing the small fragments of the text they find. [Answer] Lovecraft, You should consider reaching out to companies that have risen from the ashes of Cambridge Analytica. With hyper-personalization and targeting that allows for each person's distinct psychological vulnerabilities to be narrowed in on, you could easily launch a global campaign across various social platforms. You would need to amass a substantial amount of content across various maddening topics. People seem to enjoy their own flavors of outrage and fixation, so be sure not to skimp on the variety inflammatory articles, images, and even better... doctored videos that you produce. Algorithms can help you identify vulnerable targets as well as the topics that have the greatest likelihood to tip subjects towards mental and emotional instability. Isn't wonderful that so many people share so much information online? Just ripe for the taking. Of course you would want to start off subtly, disseminating articles that gently prod at insecurities, fears, and unhealthy fixations. As you begin to infiltrate the consciousness of the masses (aligned with their own preferred flavors), you can ratchet up intensity until you get an adequate fever pitch. It would also help to connect like-minded individuals, so they can chat and commiserate to their hearts content, aiding each other in expunging the last lingering shreds of their sanity. Facebook groups, hashtags, and social figures of leadership would be ideal. You may need to create your own at the onset, but soon enough, people will pick up much of that grunt work for you. Once fanaticism is piqued, it's time to start teasing your greatest release. You'd need to tie it in to the multitude of targeted fears and insecurities, but once people have become true believers, it will require far less heavy lifting. Sure, it will require quite a bit of capital to get off the ground, as well as many man hours, but it will be well worth the effort in the long run. Best of luck, and might I add that we aren't too terribly far off from this as it is... Yours Truly, ]
[Question] [ I did the orbital period for a planet orbiting a mass = 1 sol with a 24-hour year, it’s got a semi-major axis of 1.82 million miles - far and away beyond the Roche limit, still beyond the corona, but just a tad too hot. Problem! So what sort of star would be a black body radiator generating earth-like irradiance at 1.82 million miles distance? I’m also allowing for a strong magnetosphere to shield from solar winds, and an atmosphere sufficient to absorb excess gamma/X-rays. Earth-like is a loose term with $\pm 10^{\circ}$F mean temperature, and a little tectonic activity never hurt anyone on Mustafar - except Annakin (that’s a joke). Seriously, gravity will shake things up but not break the planet, and that’s OK. The star’s tidal force replaces the moon. The planet orbits clockwise every 24 hours and rotates anticlockwise from a synchronous rotation every 24 hours (the sun is observed to complete a $360^{\circ}$ altitude arc). You see the same sunrise/set cycle we do and a fairly similar tidal cycle as well - if not a bit more profound in variance - but the very concept of “year” ceases to exist. We just have days. No months, seasons, years, centuries, or millennia etc, etc. If this is a no-go for an earth-like climate, I can work with a Venus-like planet if that makes anything more realistic. [Answer] ## You could use a brown dwarf They are sort of 1/2 way between an actual star and gas giant. Unlike a normal star which can fuse any isotope of hydrogen, Brown dwarves only fuse the much more rare heavy isotope, deuterium (and in some cases lithium). Since most of their mass is un-fusible, their temperature typically ranges from about 250-2000 degrees Kelvin allowing for much lower orbits than you could have of other stars. They are also, as their name suggests, not very big. They all tend to be about the same size as Jupiter, but are more dense ranging from 13-90x Jupiter's mass (0.018-0.086 solar masses). Using this <http://www.1728.org/kepler3a.htm> calculator, to determine orbital radius, and this one <http://www.astro.indiana.edu/ala/PlanetTemp/index.html> to determin temperatures, I could determine that an Earth like planet around a medium sized Brown dwarf could maintain Earth like temperatures with about a 24hr year. * Mass of Brown Dwarf: 0.037 solar masses * Orbital Distance: 0.0064 AU * Roche Limit: 0.0012AU (safe) * Average Surface Temp w/ an Earth Like Atmosphere: 30 Celsius * Apparent Size of star in sky: ~16 solar radii ### How to beat Tidal Locking That said, tidal locking at this orbital period is a very real problem. It is going to happen, and it is going to happen very quickly in geological time scales. The only way to maintain a day-night cycle on a planet with such a short orbital period is with spin-orbital resonance. This is a special kind of tidal locking were the orbit finds an optimal pattern of rotations to orbits. Mercury does this in the form of a 3:2 resonance meaning that it rotates around its axis exactly 3 times for every 2 orbits. In this scenario, a day lasts for 2/3 of a year; so, you should instead have a 36hr year and a 24hr day. You would technically have seasons in this scenario, but they would be so short that they would be pretty unnoticeable in terms of day-to-day life. This phenomenon is believed to be caused by a strong gravitational pull from a 3rd body which you could achieve by making this a binary star system, (brown dwarfs are not believed to support gas giants.) * Mass of Brown Dwarf: 0.047 solar masses * Orbital Distance: 0.0092 AU * Roche Limit: 0.0014AU (safe) * Average Surface Temp w/ an Earth Like Atmosphere: 30 Celsius * Apparent Size of star in sky: ~11 solar radii [Answer] Interesting question, there should be a calculator around to check a scenario like that, only I could find none. There is several other calculators and tables which can help answering this question: [Spectral type characteristics](https://sites.uni.edu/morgans/astro/course/Notes/section2/spectralmasses.html) [Orbital period of a planet](http://www.calctool.org/CALC/phys/astronomy/planet_orbit) [Calculation of Habitable Zones](http://depts.washington.edu/naivpl/sites/default/files/hz.shtml) From a quick estimate, this (1-day orbit) is not possible with a main sequence star. If we take the smallish M8 star, it would have a mass of 0.17 suns, luminosity of 0.002 and 2700K surface temperature. A smaller star would be a brown dwarf and could not realistically support life as we know it on its planets. The calculations would give us an orbit radius of 0.011 AU, while the habitable zone would span between 0.047 and 0.094 AU, which is at least 4 times farther from the star. In short, our 1-day planet there would be worse off than Venus. However, if we don't restrict ourselves with main sequence stars, there are options. White dwarfs are known for very high mass to luminosity ratios as well as long term stability. Let's pick [Van Maanen 2](https://en.wikipedia.org/wiki/Van_Maanen_2) star, which is a white dwarf 14 light years away from Solar system and see how a planet can manage on an orbit around it. Van Maanen 2's mass is 0.68 suns, luminosity 0.00017 and surface temperature is a much more comfortable for us 6220K. The orbit for 1-day year results in 0.017 AU, while habitability zone ranges between 0.012 and 0.021 AU. Bingo! Yes, our planet can orbit a white dwarf. However, it would likely be tidally locked, and at this point it's not entirely clear to the science if life can exist on a planet like that, even if it has the proper (on average) temperature. [Answer] # Here are some findings For a star with 1 solar mass, and at the distance you'd need (2,927,699.613 km) for a 24-hour year, you could have: * A star with a radius 0.019578 times that of the Sun, but with the same power density as the Sun. * A star with a power density about 0.0003834 times that of the Sun, but with the same radius as the Sun. These are the two extremes, but they would give you the correct solar output. The observed radii of white dwarfs have been about 0.8–2% of that of the Sun. This might possibly work for your solution, but you also have to take into consideration that white dwarfs have higher energy output per unit volume than the Sun does. [Answer] You can not get a habitable planet with Earth like temperatures orbiting a star with a mass equal to the Sun with an orbital period or year one Earth day long. Thus you will have to settle for a star a lot different from the Sun for an Earth like planet to have a year one Earth day long. The mass of a star (and its age to a lesser degree) will determine how much radiation the star will emit. The amount of a radiation a star emits will determine the distances of its habitable zone where a planet could orbit and have Earth like temperatures. The mass of the star and the orbital distance of the planet determine the planet's orbital speed and the length of its year. There are known exoplanets with years less than one Earth day long. But they are not orbiting in the habitable zones of stars with masses equal to that of the Sun. <https://en.wikipedia.org/wiki/List_of_exoplanet_extremes#Orbital_characteristics>[1](https://en.wikipedia.org/wiki/List_of_exoplanet_extremes#Orbital_characteristics) There are exoplanets known to orbit in the habitable zones of their stars, making those exoplanets potentially habitable exoplanets. <https://en.wikipedia.org/wiki/List_of_potentially_habitable_exoplanets>[2](https://en.wikipedia.org/wiki/List_of_potentially_habitable_exoplanets) Their year lengths vary widely. The four planets in the habitable zone of TRAPPIST-1 included the three potentially habitable exoplanets with the shortest known days; 9.2 days, 6.1 days, and 4.05 Earth Days. I haven't done calculations, but I think it is possible for a planet in the habitable zone of a star to have a year as short as one Earth day. But all the potentially habitable worlds orbiting in the habitable zones that have very short years orbit around very dim red dwarfs of spectral class M. And those stars are much less massive than the Sun. For a planet to orbit in the habitable zone of its star with a year one Earth day long, it would have to orbit around a class M star even dimmer than TRAPPIST-1 even closer than TRAPPIST-1d does. So there would seem to be absolutely no possible way for that star to have the same mass as the Sun. It has been calculated that planets orbiting in the habitable zone of a red dwarf star would become tidally locked to their stars, with one side constantly facing the star and having eternal day and one side constantly facing away from the star and having eternal night. And it is controversial whether a planet could be Earth like and habitable if it was tidally locked to its star. One way out of that problem would be to have the Earth-like planet actually be an Earth like giant moon of a giant planet. The moon would orbit the planet which would orbit the star. The Moon would become tidally locked to the planet and not to the star, and so it would have a daily cycle of light and dark equal to the period of its orbit around the planet. If you try that, it would be more likely for the Earth like moon to have an orbital period of one Earth day around the planet, and for the planet to have an orbital period of at least several days around the star, instead of the planet having an orbital period of one Earth day around the star, and the moon having an orbital period of a fraction of an Earth day around the planet. So that would not be exactly what you want. Of course it is always possible, depending on various theories about the subject, that a tidally locked planet orbiting close to a red dwarf star could remain habitable. Since Trappist-1 is spectral class M8V a habitable and Earth like planet with a year one Earth day long would probably be class M9V, or even dimmer. If a red dwarf with spectral class M9V would still be too luminous to have a Earth-like planet with a year one Earth day long, you would have a problem selecting an even dimmer type of star. You might need to go with a white dwarf star. White dwarf stars are much hotter than red dwarf stars, so each area of their surface emits a lot more radiation than the same area of a red dwarf star does. But white dwarfs can be very small, and so can have a lot less surface to emit radiation from. Thus the dimmest white dwarf stars might be a lot dimmer than the dimmest red dwarf stars. White dwarf stars, despite their smaller sizes, are also very dense and so are more massive than red dwarf stars. Thus a planet orbiting a white dwarf star might have to orbit faster to stay in orbit, and have a shorter year, than it would have if it orbited a red dwarf star at the same distance. So white dwarf stars would be a good choice for an Earth like planet with a year on e earth day long. Except for the history of white dwarf stars. White dwarf stars were once massive stars which had to burn their fuel very quickly, and so have run out of hydrogen to fuse, expanded into red giants, and then shrunk down to tiny white dwarfs shining with leftover heat. That process would have destroyed any planet orbiting that close. So the Earth like planet would have had to have been moved from someplace else into its present orbit by rather unlikely natural forces or by a highly advanced civilization, and then remained in its new orbit for billions of years while it gradually developed Earth like conditions on its surface. another possibility would be to have the planet orbit around a brown dwarf. A brown dwarf is an object more massive than a planet and less massive than a star, that would mostly emit invisible infrared radiation. A planet orbiting a brown dwarf of the right mass and luminosity might possibly have a year one Earth day long while orbiting within the habitable zone of the brown dwarf, though I haven't made any calculations. So there are several possibilities for someone to calculate an orbit within the habitable zone with a length of one Earth day. One) a red dwarf, probably spectral class M9V. Two) a white dwarf, where the planet has been moved into its present orbit billions of years ago, after the star became a white dwarf. Three) a brown dwarf. [Answer] For a solar mass star with an Earth-like climate in a 1-day orbit, you'd need a white dwarf. This nevertheless presents a few problems. Firstly, the white dwarf is the end state of stellar evolution. The progenitor star would have been much larger, especially during the giant stage, which would destroy the inner planetary system. You've also got the problem that a young white dwarf star is extremely hot and luminous, which would boil off all the water from a nearby planet long before the star cooled down enough (to a similar temperature to our Sun) for the 1-day orbit to be in the habitable zone. The way to get around this is to form the planet at a later date. One way to do this is to have the orbital changes due to the mass loss from the progenitor star destabilise an existing planetary system, eventually kicking a planet into an orbit where it gets ripped apart by the white dwarf's gravity. This might produce a disc around the white dwarf that may be able to form a new generation of planets. If the instabilities take a sufficient amount of time to work themselves out, you might be able to avoid the worst of the early luminous stage of the white dwarf's evolution. An alternative is that the white dwarf is part of a binary system, and when the second star goes through its red giant stage, the new white dwarf captures enough material to produce a planet-forming disc and create new planets. Of course, if too much material falls onto the white dwarf you'd run the risk of the system undergoing nova explosions or a type Ia supernova. Once you've somehow got a planet into the "habitable zone" of a white dwarf, the next main problem is tidal heating. The tidal forces at that distance from a white dwarf will be severe: even tiny amounts of orbital eccentricity will result in a world that makes Io look stable, consequences of which could include a runaway greenhouse effect (a.k.a. a "tidal Venus"), magma oceans and other general unpleasantness. Tidal forces will act to circularise the orbit on short timescales, but if there's another planet in the system then the effect of its gravity on the orbit could easily trigger disaster. ]
[Question] [ Some islands can survive for very long. Madagascar, for example, has been around for 80-100 million years and is likely to remain isolated for hundreds of millions of years more. Volcanic islands, however, are generally much more short-live, due to the fact that the same spot rarely has access to magma for long. The oldest one I know of is Iceland, which has existed for about 13 million years. However, is it possible for an island - ideally on Earth - to somehow remain a) above sea level and b) isolated from the mainland continents for a period on the scale of, let's say, 100 million years? If so, what conditions would be necessary for it to happen? [Answer] By being an island arc volcano. You seem to be referring to [hotspot volcanoes](https://en.wikipedia.org/wiki/Hotspot_(geology)), which are fed by abnormally hot regions of the Earth's mantle. As the continental plates drift by overhead, the area fed by the hotspot changes over time, and so you end up with an island chain in which the older, dormant islands have eroded to almost nothing, but the islands still being fed by the hotspot (and therefore, still volcanically active) are much larger. Hawaii is a good example of an island chain produced by a moving hotspot. You can clearly see the movement of the hotspot over time, from Kure (formed ~28 mya and now completely eroded, leaving just an atoll) to Hawaii, where it now approximately resides. [![enter image description here](https://i.stack.imgur.com/utGeh.png)](https://i.stack.imgur.com/utGeh.png) [Island arcs](https://en.wikipedia.org/wiki/Island_arc), however, are chains of volcanoes that form along subduction zones: places where two continental plates meet, and one is forced beneath the other. This feeds volcanic activity, and as long as the plates continue to subduct, this activity will continue. The Aleutian Islands, at the boundary of the Pacific and North American plates, are an example of an island arc. They are thought to have formed around 50-55 mya, and are [still volcanically active](https://en.wikipedia.org/wiki/Makushin_Volcano). Just as you can trace the path of the Hawaii hotspot by looking at the islands, you can trace the Pacific/North American plate boundary by looking at the Aleutians: [![enter image description here](https://i.stack.imgur.com/M9fak.png)](https://i.stack.imgur.com/M9fak.png) So all you need is for your island to be located at a subduction zone that's been around for 100 million years or more. Tectonics will take care of the rest. [Answer] You are looking for a [Microcontinent](https://en.wikipedia.org/wiki/Continental_fragment). Microcontinent is basically a shard of a larger continental plate that is drifting separately from its parent. There may be active volcanoes on this landmass (like in New Zealand) or not (like in Madagascar). The landmass can be large (like Madagascar) or small (like Seychelles). In either case this is not a hot spot volcanic island - I don't know if that fits your criteria. Mirocontinent (unlike a hot spot volcanic island) can remain dry land almost indefinitely, because it is made up of think continental plate rather than deformed oceanic plate. Microcontinents do tend to sink, though, but, unlike for volcanic islands, this fate is not mandatory. Microcontinents can remain separated from large continents for tens of millions of years. This period of separation is limited mostly by the randomness of continental drift process. For example, India had been separated from Gondwana some 100 million years ago, but then some 50 millions ago it collided with Asia, and remained connected ever since. [Answer] The example of Madagascar which you stated is also the answer to your question. Size matters. Once the supply if new lava stops, no surface will be added. Considering that erosion and crust sinking slowly reduce the surface of the island, the larger the island the longer it can survive under the wear of times. [Answer] On that timescale, a series of pole shifts could help your volcanic island avoid erosion. If soon after the volcano stopped providing new magma, the poles shifted such that the island became completely covered by ice year round, and if that ice were thick enough and heavy enough to remain motionless across the millennia, then the rock underneath might remain un-eroded. Then a second pole shift, say a million years ago, could bring the island back out from under the ice more recently, making it available for your use. ]
[Question] [ Let's say there is another planet in our solar system that harbours sentient life and this sentient life can build castles, buildings, and other such structures. When would we notice that? We can see the planet but we can't see lifeforms through basic telescopes - they're not close enough. They don't have technology to send signals - we end up finding them. [Answer] > > The Great Wall of China can be seen from space! > > > Not quoting you, obviously, but it's a thing we've all heard a lot. We can see a load of things from space - with Google Earth I can see my house! It's good that you don't seem to be making that mistake, but on the off chance that was in your head, I just wanted to make sure we're on the same page. I was a bit confused by your question though: > > We can see the planet but we can't see them trough basic telescopes > > > I'll do my best to answer your question anyway. I'd like to direct your attention to [Mars](https://en.wikipedia.org/wiki/History_of_Mars_observation#Early_telescope_observations). According to the link I've attached, many famous observers tried to learn about Mars with a standard advanced telescope of their time. They learned about how certain parts of Mars's orbit took it further away then it should've been, indicating some knowledge of a non-circular orbit and one that is not synchronous with Earth's orbit. They also started noticing Mars's polar ice caps expanding and contracting. Later on, they started noticing the massive dust storms we know Mars for (although they didn't know that that was what it was). If this is the tech your people have, they'll probably only notice this much. All of these observations took place by early 1800s. [By the mid-1800s](https://en.wikipedia.org/wiki/History_of_Mars_observation#Geographical_period), people were noticing features on Mars itself. People started making maps of the surface by this time. Not all of it was accurate, but what was very accurate was the rotation of Mars (which we figured out to be accurate within a tenth of a second). [By the early 1900s](https://en.wikipedia.org/wiki/History_of_Mars_observation#Martian_canals) we had maps of canals on Mars (we were taking photographs at this point), but later on we noticed other features, but almost a clear absence of canals. Just by this level of tech, we can safely assume that without putting something much closer to Mars (like a satellite) we can't be too sure of buildings built by an alien race unless it's really obvious and changes the planet itself. Now, however, we can take pretty great images of Mars from Earth (no need for satellites), but our optical and digital zoom technology had to be refined a lot, and our best images are taken from out of our atmosphere to prevent distortion. Also, one reason we have such nice pics of Mars is because it has barely an atmosphere, so nothing to get in our way when we're looking at it from outside. To look at your question again: you can't see this planet with a telescope, but you know it's there. Mars in our real world case could be spotted with the naked eye and observed with a good, old-school telescope. We still can't see anything on Mars though - until some nice pass-bys with various probes and satellites around Mars. That's despite having an advantage over your case. With your logic, the planet would need to blow up or something so we can notice it. I'll correct this answer if that's not what you meant. EDIT: From comments and from clarification from the asker, I'd like amend my answer. Unless the structure the aliens were making on this planet were big enough to be noticed like dust storms, polar ice-cap expansion/contraction, or some other massive weather phenomenon, the odds of your people sitting on another planet being able to notice them is pretty slim. So, if they build a bunch of Empire State Buildings - no one would know. Now, if they had fast-growing cities or other megastructures under construction, they could be noticed, given that these construction projects weren't mistaken for weather activity. [Answer] It would depend on the distance to the planet, the composition of its atmosphere, their technology level, and our own. Translated to our solar system, if they were on Venus we'd never know about them until we visited the planet because its cloud cover makes seeing much of anything on the surface impossible with visual instruments. On Mars, a large enough structure (say a few dozen to hundreds of kilometers across) might be visible from earth with a powerful enough instrument. On Titan, forget about seeing anything, the optical resolution of your instruments will not be enough to see things much smaller than the size of Titan itself. But even on Mars, you're looking at MASSIVE structures. Say something the size of a major mountain. And how'd you determine it was artificial? We've long thought the "face on Mars" was artificial, until a probe in orbit around Mars got images of high enough resolution to see that it wasn't. [Answer] Continuing on from cyber101's good answer, studying the early history of sending probes to Mars is probably a reasonable place to start and then add a dose of speculation to cope with your scenario. Despite studying Mars through telescopes for many years, it wasn't until the [Mariner 4](https://en.wikipedia.org/wiki/Mariner_4) probe in 1965 that we got images from Mars good enough to resolve large craters. That was from a range of less than 10,000 km using a slow-scan video camera attached to a telescope. A couple of things came out of that: the surprise that there were visible craters; and the acknowledgement (by Carl Sagan and others) that the 22 images obtained was not really enough to "conclude there was no intelligent life on Mars". However, as our probes get better, and once the alien civilisation gets advanced enough to build many large cities, starts transmitting radio or other electromagnetic waves into space, or starts to radically alter the landscape with the kind of infrastructure associated with a civilisation - farms, roads, airports, docks, artificial lights, that kind of thing - the signs of intelligent life become harder to miss, even from far away. Even now, though we are sure there is no intelligent life on Mars, the question of whether there ever was any life on Mars is still an open one. [Answer] Depending on how you define it, one of the larger structures humans build is a city. The built-up area of [Beijing](https://en.wikipedia.org/wiki/Beijing) has an area over 4000 square km. The lunar crater [Aristoteles](https://en.wikipedia.org/wiki/Aristoteles_(crater)) has a diameter of 87 km, so an area about 6000 square km. So Beijing ought to be visible from another planet with a good telescope. Possibly by way of the concentric ring-roads, of which it has seven. When people paint a giant target on their planet, possibly somebody should look. For viewing of Earth from Mars, the Earth would show its night side quite frequently. City lights might be the first things visible. Viewing from a planet closer to the sun would mean it's hard to see the night side of the planet. For individual artifacts, possibly airports would be a give-away. The [longest runways](https://www.worldatlas.com/articles/longest-runways-in-the-world.html) are several miles. A structure this long, and this straight, is a strong hint that somebody is getting up to something artificial. [Answer] As others have said, that depends on the planet's distance to us and its atmosphere. For thick atmospheres, such as Venus and Titan, we will know they are there when we either: * detect their radio emissions - however the question says this won't happen. * send a probe; * find signs of life in their atmospheres through [spectroscopy](https://en.wikipedia.org/wiki/Spectroscopy). The latter will only work if the other planet is closer to the Sun than we are. The point being that there will be no visual confirmation in those cases. For atmospheres like Mars', by around the 1800's. Back then astronomers such as Giovanni Schiaparelli saw [what they thought to be canals on Mars](https://en.wikipedia.org/wiki/Martian_canal). Those were not canals. But if there is a civilization in another planet, they will have an impact on that world's forests (or equivalents), which would be measurable throughout time. Mars is not geologically active, so any fast changes on its surface would most probably be driven by bioological activity. Whether that activity is intelligent or not would take more time to assess. If they could have radio as we do, we would start communicating around the time both planets have it. Since the question forbids that, we will get visual confirmation by the 60's, when the first interplanetary probes are launched (Mariner 4 arrived on Mars in 1965). ]
[Question] [ I am in the early stages of planning a story called The Four Flamingos of the Apocalypse. The premise is that the Four Horsemen have manifested on the surface of the earth and are tasked with bringing about the apocalypse, but due to an unforeseen quirk they've all incarnated as flamingos. As flamingos they're going to find it very hard to do the kind of damage necessary to bring about the apocalypse, so I'm looking into the kinds of resources flamingos have available and what they could do with it. Some flamingos live in sodium salt lakes, and I wonder how much potential that has as a resource. I suspect I'll end up giving the flamingos some non-real-world capabilities but I want to figure out what their options are before blessing them with any special abilities. My chemistry knowledge is unfortunately quite poor for a handful of reasons, and most of the information I have seen online about sodium salts makes little sense to me. [Wikipedia has a short article on it](https://en.wikipedia.org/wiki/Sodium_salts) but none of the options sound particularly dangerous. Can anybody give me any pointers? [Answer] [Soil salinity](https://en.wikipedia.org/wiki/Soil_salinity). By bringing enough salt to the farmland, you can destroy the agriculture system of your world. This process is called soil salinity, and it can harm or even stop plant growth, damage the infrastructure of buildings, and pollute the underground water. I know one of the four horseman is Famine, and salinitize the soil can surely make it happen. [Answer] Well, there's sodium, and there's sodium. You can solve your "which salt is bad?" problem by ensuring that every salt is bad. [Sodium-22](https://www.sciencegateway.org/isotope/sodium.html) is a radioactive isotope that has a half life of 2.6 years (long enough to hang around a bit, but short enough to be quite hot) that decays by positron emission (which will then inevitably interact with an electron, producing a nice gamma ray for your enjoyment). IF you're less patient, there's always [sodium-24](https://en.wikipedia.org/wiki/Isotopes_of_sodium#Sodium-24), but with a halflife of under a day you'll have to transmute it at the point of use rather than creating some ahead of time and letting it spread around. What's the point of radioactive sodium? Well, sodium appears pretty much everywhere in a human (and indeed, in a vast array of animals and other living things) which means that once radioactive sodium gets into you, it gets into every bit of you and causes damage to everything. People assume "pestilence" means a plague of infectious organisms... parasites, viruses, bacteria... but it could just as easily be a biosphere-wrecking radiochemical that causes a cancer epidemic. [Answer] Sodium chloride, one of the most common sodium salt, is used as sapidity enhancer for ages. It's not immediately toxic, though its excessive assumption may cause hypertension in late age. I guess your flamingos want something more rapid. How can sodium salts be dangerous? They cause dehydration of organic material. If you bury a body in salt, it will lose most of its water. In the past it was used as a method to preserve meat; actually it was the only way to preserve meat before refrigeration was invented. But if you bury a living person under salt, suffocation will kill the person way before dehydration. So, if you want, burying the cities under salt is an option. Moreover, if you spread salt on farmland, most of the crops will not grow. Therefore it is possible to induce a massive famine. What can improve the damage potential is if you can somehow separate the sodium from the halogens to which it is bonded. Metallic sodium strongly reacts with water, producing hydrogen and flames. When in contact with the skin causes deep burning. [Answer] One of the sodium salts mentioned in the wiki is [Diclofenac](https://en.wikipedia.org/wiki/Diclofenac). If your horsemen have the power to produce it, then they can cause mayhem in the world. Diclofenac has been used to treat farm animals for a long time. Not all of their flesh becomes meat, and when vultures eat the carcasses, it destroys their kidneys. If the Pestilence Flamingo spreads diclofenac over the world, all birds would die. This would disrupt almost every land ecossystem. The biosphere as a whole would suffer. Other animals are also affected. A global cloud of diclofenac would poison other creatures as well (I have used it to kill spiders). Once the biosphere is wrecked, the Famine Flamingo would surely reign (no more chicken, most animals poisoned), and the War Flamingo would have people fighting for the remaining food and other resources available. At the end, everyone would be taken under the wings of the Death Flamingo. ]
[Question] [ Trying to develop a fictional scenario with a 'believable' theory as to how a Nuclear War and resulting Nuclear Winter could turn into a millennial scale ice age. By 'believable', I mean that it passes basic Science Fiction rules, but not necessarily rock solid Hard SF rules. If it's completely impossible, then is there a scenario where prolonged or periodic use of nuclear weapons over say a hundred years might provide sufficient forcing to make it happen. [Answer] There is some reason to believe that the world was heading into an [ice age](https://en.wikipedia.org/wiki/Little_Ice_Age) when the industrial revolution started. The industrial revolution of course added a great deal of carbon dioxide to the air. If you are willing to believe that this prevented the ice age, nuclear winter combined with an end to burning fossil fuels could lead to the previous ice age resuming. To repeat, the hundred years part would be caused by ceasing to burn fossil fuels (presumably because the nuclear war killed off enough people that it was not feasible to continue the drilling, transportation, and refining tasks). It would be triggered by the nuclear war. The actual nuclear war would cause a few years of cold. But the real cold snap would hit as the world reabsorbed the excess carbon dioxide. [Skeptical Science](https://skepticalscience.com/human-co2-smaller-than-natural-emissions.htm) says that human activity produces a net 29 gigatons a year of carbon dioxide. And everything else removes a net 17 gigatons (`439 - 450 + 332 - 338`) from the air. So removal of human activity would switch the world from adding 12 gigatons per year to subtracting 17. So two years would take us back three in terms of carbon in the atmosphere. A hundred years after the war, the Earth might be back to where it was a hundred fifty years ago: in the Little Ice Age. Two years of nuclear winter followed by a warmer period starting a century of cooling temperatures as the industrial age's global warming reverses followed by a millennium of ice age. If that works for you, it seems reasonable at the science fiction level, particularly as our ability to model climate is still rather weak. Since we don't know how things do work, it's hard to say that that's not how it works. It's also possible that we could tweak this up a bit. Because nuclear winter works by throwing dust in the air, which reflects light. When that dust settles, it will sometimes cover up plants. Those plants decay underneath the ground and start the process of creating new fossil fuel. Meanwhile, new plants grow on top of them, pulling carbon dioxide out of the air and releasing oxygen. The heat from the nuclear weapons might cause methane in the atmosphere to ignite. Since methane is a worse greenhouse gas than carbon dioxide and water vapor, this might cause some cooling. The world might become dryer. Because the two years of nuclear winter will reduce the amount of evaporation from oceans and lakes while the colder weather will cause the ice caps and glaciers to grow. Larger ice caps and glaciers may reflect more light and while plants won't grow on top of them, they'll likely keep the plants that go under them from rotting and releasing carbon dioxide. Dryer means fewer clouds holding temperature in at night. It's not ridiculous to think that these effects might accelerate the cooling century. [Answer] If you simply want an ice age, you may not even need the nuclear winter. Simply let the Sun enter a 1000 years long period of slightly lower intensity. It could be large enough to counteract anything humanity does to heat up the climate. We have evidence that the Sun's output is not constant over large timescales. It is theorized that such low activity was partly responsible for earlier ice ages. The Sun is still far from fully understood. Predictions about its solar cycles are not 100% accurate. "Your" Sun can enter an unforseen, low intensity period. For more in depth information on solar cycles: <https://en.wikipedia.org/wiki/Solar_cycle> [Answer] Hit a large [gypsum](https://en.wikipedia.org/wiki/Gypsum), or other sulfurous compound, deposit. The main reason the that [Chicxulub](https://en.wikipedia.org/wiki/Chicxulub_crater) impact caused long term climatic chaos wasn't the initial rocky impact ejecta, they were bad but what caused hundreds of years global temperature oscillations was that the impact happened in an area rich in carbon and sulfur bearing rocks, mainly limestone and gypsum, and it pumped geologically significant quantities of both Carbon and Sulfur oxides into the atmosphere when it vapourised those rocks. If nuclear weapons were to burn off extremely large quantities of sulfur compounds and create a lasting blanket of [sulfur aerosols](https://en.wikipedia.org/wiki/Stratospheric_sulfur_aerosols) then an ice age is a distinct possibility. ]
[Question] [ In my late-Victorian-based world, mechanical contraptions are incredibly advanced due to the early discovery and quick popularisation of mechanical computation. The science of writing instructions for such machinery has allowed an effective AI ruler to come to power. The insecurity I now face is how compact the parts required can be produced and assembled. The parts used would probably be akin to those in [this training video on a US-Navy mechanical computer](https://www.youtube.com/watch?v=s1i-dnAH9Y4). What is the smallest I can possibly make a simple, 16-toothed gear wheel? If you have any concerns towards possible problems of having such small machinery, such as lubrication or friction, please feel free to voice them. [Answer] In the 19th century, watchmakers were producing watches small enough for ladies to wear on their wrists. These would have included tiny gear wheels, including escapement wheels with more than sixteen teeth less than an eighth inch across, and actual gears significantly smaller than that. Screws as small as 0000 size (approximately .02" diameter) could be produced by automatic machines by the end of the 19th century. The original Babbage Engine was large and heavy, but could have been reduced by more than half with the best machining techniques of fifty to sixty years later. [Answer] Through the use of a Precision or Micro Pantograph, which was used for detailed inscribing in the 1800's, gears of microscopic size could have been produced. The problem with such small gears is the microscopic nature of the surface of metals at the microscopic level. The jagged or even leafy surface of metals would make them poor gears. [Answer] There is a crusty old joke, which I'm sure predates even the Victorian era. Two teams (since the cold war, these are often depicted as US and Russia, but it could be any competing teams) are challenged with making the smallest possible pipe. Team A gets their best scientists and engineers together, and creates a tube of gold with microscopic dimensions, some crazy fraction of a human hair. They send it to team B, who sends it back. Team A says "but you just sent our own tube back: where's yours?". Team B tells them to look inside the Team A tube, where they find a sheaf of seven of Team B's tubes, made of glass. If you're familiar with the principle of [Rock Candy](https://en.wikipedia.org/wiki/Rock_(confectionery)), you'll understand the principle here. You can make any shape, stretch it out, and it becomes thinner while retaining its shape. That means there's no mechanically-limited constraint to the size of the thing. You can make a glass gear at the finest resolution of your tooling, then stretch it and the diameter will reduce as the inverse square of the length. So, I don't think generating gears smaller than they could machine would be an issue for them. Affixing those gears might, though. But the biggest issues, as others have intimated, would be wear and maintenance. ]
[Question] [ In my world an advanced alien civilization are worshiped as gods by the human population. As the gods have better things to do than actually spend time interacting with the local fauna they created a hybrid through genetic engineering, combining traits of both their own species and humanity to create something closer to humans in thoughts and feelings to interact through. Humanity perceive these hybrids as demigods much akin to classic Greek heroes like Herakles and the like. The alien technology is treated like magic, and can only be utilized by the demigods\. The reason for this is that the alien tech is more or less programmed to only respond to beings with the gods' genetic code. The demigods must place their God-Hand, their right hand that is designed to be similar to their divine progenitors, on the device to activate it. My question is are there any good reasons why they may need to utilize their god-hand specifically? My understanding of genetics would lead me to think no part of their body is technically more or less "alien" than another, even if the body exhibits more traits from the alien side than the human. Further Information:* These hybrids are the product of very advanced genetic engineering and were specifically designed the way they were. I do not know if this makes the god-hand more or less likely to make sense. *Note\: I had intended for humans to be able to utilize the god-tech by using the blood of demigods to fool the devices into letting them access the controls. More Information: The humans are pre-industrial on a planet with very little easily accessible precious metals, forcing them to exist in a pseudo-stone age level of technology. [Answer] Hand design The weapons require in*human hand to hold it. It's not merely "fingerprints" but the weapons are designed for an entirely alien hand. Maybe it's larger than the human's maybe it's smaller. Perhaps it has three fingers only, perhaps it has seven. This is up to you to design. It's both part of the design and part of the protection it has from humans - unlike a normal pistol, a human can't just take it and immediately use it. A "demigod" is genetically engineered to different but their right hand is actually disguising their alien hand. Details up to you again, but I imagine it being able to extend and split somewhat similar to cybernetic hands Ghost in the Shell* as it can be suitably discreet and also allow for some bizarre mechanisms on the devices: > > [![Ghost in the Shell GIF of cybernetic hands expanding](https://i.stack.imgur.com/nOtex.gif)](https://i.stack.imgur.com/nOtex.gif) > > > This is intentional both for protection of the devices and the hybrids, as well as keeping the mystery around the "godly powers" - a seemingly non-alien can use the tech or "magic" while humans cannot. Something to keep in mind - given enough time and technological level, humans should be able to adapt this technology to be used by them. How exactly is up to you but it will likely make it awkward to use - perhaps humans need two hands or maybe two of them are needed to operate it. This makes the tech still alien but usable to humans. Blood requirement This has been put in place as a safeguard against the hybrids. Just so they don't get drunk with power or even turn on their creators. The weapons literally require blood to power them. The aliens might have gene-modded the hybrids to have blood actually be some sort of fuel, or it might not be. At any rate, once the hybrid takes hold of a device, some amount of their blood is extracted with activation. This ensures that a hybrid cannot use a device too often or else they would die. The blood need not come from the God-Hand but the God-Hand might be designed to easily facilitate this with some sort of opening to a vein that fits into the mechanism and makes the transfer painless. Humans seeking to use the alien devices would require blood from the hybrids. So, they might need to hunt down "demigods" to gain more blood. An even darker twist would be capturing the hybrids and harvesting blood from them. A somewhat obvious plot hook here is that if aliens designed the blood requirement to limit the power each individual hybrid can wield, an ambitious demigod could just use other demigods' blood instead of sacrificing his own, which means he can use alien tech with a lot less restrictions. Be that in order to rule over the entire world or even take the fight to his creators or something else would depend on the story. Whatever the case, it can serve as a vehicle to have a "religious war" sparked where one (or more) demigods start a struggle for dominance and aim to capture other demigods. [Answer] Blood Veins The question here is that what does the God Hand has to have different from a human hand to be recognized by the machine, but we are limiting our thoughts only on the outside factors like FingerPrints, I suggest you picture the inside of a hand. Your God hand may not need to look different than a normal human hand, in fact, it may look exactly like a human hand, but all it needs is to have a different structure inside it. In a human hand, there are bones, blood veins, arteries, capillaries (I am not a doctor though). But your god hand may have an entirely unique set of things like (I don't know) bones with an alien specific grain structure, different size of blood veins, no capillaries or literally whatever you wish for. Your alien machine works something like this: when a god hand is placed on it, the machine scans the inside of the hand, (but you can't tell just by looking at it) and recognizes the alien hand and along with this it puts a needle inside the palm to take blood sample for DNA matching. Now it will get tricky when humans want to use it, in this case, they might have to have the full god hand, or just the palm to use it, if humans are advance or can steal god tech, they may acquire a 3D printer to print a god hand of their own or they can simply take one off from the demigod. [Answer] Hereditary crystal. 1. Demigodhood is passed thru the mother. Male demigods can conceive offspring who might be different than regular humans, but their children do not have Godhand. 2. Demigods have a crystal, or jewel, or pearl within the tissues of the hand. That is how the Godhand works. It is like an RFID chip. The lineage of a given demigod can be traced through the nature of the crystal. A demigod may or may not know how it works. 3. When a demigod is pregnant, a piece of her own crystal breaks loose and makes its way into the fetus. Maybe it goes directly to the hand or maybe it migrates from inside the body out to the hand during childhood. 4. The mother does not lose enough crystal to make a difference. She gradually regrows what she has lost. 5. The child's crystal will grow with the child; at some point it is big enough / in the right location to be used as the Godhand. 6. The crystal quickly loses its power if removed from a living body or if life is removed from the body it is in. But possibly it might be transferred... [Answer] If your aliens are intentionally posing as gods, they probably will use the hand as symbol of their power. Thus the device designed to have a hand slot, which in reality unlocked by genetic code and activated by pressure. [Answer] The tech has biometric authentication akin to the fingerprint authentication on some phones, and requires alien fingerprints in order to activate. Human fingerprints fail this test, so they have to use their alien-shaped hand to activate them. This would also allow humans to hypothetically bypass these restrictions by using something like sticky tape to copy the alien fingerprints; the Mythbusters have proven that it's possible to do so for human fingerprint biometric security. ]
[Question] [ The creatures I am working with are primate-like, hexapodal aliens with a terrestrial/ arboreal lifestyle. On flat land they are able to walk bipedally, freeing up their top 4 arms for manipulating objects. In trees or tree-like structures, they tend to use 4 or all 6 limbs. (Although technically they could get around using only 3 since they have poseable feet) Ground-based combat would be fairly similar to humans, but with this information in mind, What weapons/ methods would be most effective for arboreal combat? Assume that they have at least 1 or 2 hands available, and that this is excluding bows and other projectile weapons. To avoid falling to one's death, weapons that are likely to shift the user's center of mass around should be taken with caution. The technology level can be anything available before the invention of gunpowder. Finally, the weapons in question don't necessarily have to be orthodox in regards to "regular" combat, any hand-held method of removing the enemy's life is allowed. [Answer] Spears and Clubs By far some of the simplest and easiest weapons to use and make, spears and clubs have been used as weapons since the dawn of Man, and for good reason. If your creatures have four arms, they can use all of them on a spear and deliver a very powerful strike. Or a spear can be used in just one hand if needed. The same goes for a club. The spear would likely be your best choice, you can use it from a distance and all you need to do it thrust it towards someone. Spears would also be good against people who were in trees as well, they have a long reach so you can easily stab someone in the trees. Pikes may also be an option, they’re basically just longer spears, may be good for very high trees. In reality, any melee weapon can be used effectively, you may need some way of keeping yourself attached to the tree, maybe via a harness or just using your other limbs. Here are some videos demonstrating how a four-armed creature may use melee weapons: <https://www.youtube.com/watch?v=wZz06vgKSFE> <https://www.youtube.com/watch?v=aoAy475VqIo> War Darts [![A large dart with a metal weight towards the end](https://i.stack.imgur.com/by4Q6.jpg)](https://i.stack.imgur.com/by4Q6.jpg) <http://www.kultofathena.com/product.asp?item=AH4220N&name=Late+Roman+Plumbata+War%2DDart+%2D+Small> War darts, called plumbata by the Romans, were basically darts that were thrown at your enemy. They had a weight on them to give the dart a bit more stopping power. Your creatures could carry these, throwing them at targets if they are on the ground and dropping them on targets if the creatures are in the trees. Similar weapons were used by WW1 pilots, dropping darts onto planes below them. A more crude option is to just use rocks. Bagh Nakh or Shuko [![enter image description here](https://i.stack.imgur.com/tJ3aN.jpg)](https://i.stack.imgur.com/tJ3aN.jpg) <https://www.allcombat.com/shop-gear/hand-claws/> Meant as tools for climbing trees, these can also be used as effective weapons. They are often called tiger claws because of their shape and how, when you strike with them, its like you are clawing your target like you are a tiger. These would also fit well into the theme of these creatures climbing trees, you could say its very tree-matic. Grappling Hook An unconventional weapon to be sure, it is primarily a tool meant for climbing or attaching an anchor a far away point. However, being made of steel, if you got hit with one of these i don’t think you’d be walking away. You may also be able to drop it down, hook someone under the chin or arm and hoist them off the ground. Again it fits very well into this idea of the creatures climbing trees, it would not be ideal for tree-to-tree combat though as it would likely get stuck on all the branches. Although, that could be useful for shaking branches to make them fall. You could also hook it behind a leg and pull them out of the tree. Handsaws or Wood Axes Whilst not effective weapons per se, you could easily use them to kill someone. Simply saw or chop part of the way through some large branches, when your enemy steps on it the branch will break under their weight, causing them to fall to the ground and break their bone. Or you could cut part way into the whole tree and fell it when they are in its branches. [Answer] As stability and maneuverability are very important for fights in the canopy blade weapons are going to be chosen over blunt, top-heavy weapons (maces and axes) and long weapons (spears and polearms). One-handed blades (knives, short swords, arming swords, falchion, and sabers) seem better than two-handed ones (long or great swords) for this reason. You excluded ranged weapons from this discussion, but I´m still going to mention them because I´m a completionist. Bows and crossbows could fit into two different functional groups. Crossbows and big, powerful bows (longbow) would serve as sniper weapons while rapidly firable, small bows (short bows) will be used by raiders. Think steppe-nomad tactics. Blowing darts might be interesting if strong poisons are commonly available. There is also a large variety of one-handed ranged options (rock, knife, sling, axe, javelin, ...). That said javelins might also be a one-handed melee option with an added throwing option. Let's call these "hurling spears" and imagine them to look like Roman pila or Zulu spears. For shields, I think small ones like bucklers are much better for canopy mobility than large ones (round shields, kite shields, ...). Great shields for missile infantry might be a good idea for sieges and drawn out fights involving ranged units. Armor wise I think metal would not be a great idea since due to stamina issues. While full plate armor is way less limiting than most people think (scaling climbing walls and doing handstands is quite possible), the three-dimensional nature and obvious opportunity for stealth in arboreal warfare make linen (gambesons are awesome), leather, wood, and bone armor quite appealing. If you need to limit the weight go for helmets and hand protection and some light body armor. The first two spots are vital and very prone to injury. ## Let's conclude this with outfitting the perfect warrior He´s got a metal helmet and metal gauntlets and the rest of his body is covered in linen armor reinforced with wood or bamboo and bones. There are lashes allowing easy conversion into a ghillie suit. Let´s give him a buckler and some kind of short sword (go for aesthetics you like, roman gladius or sparta, saxon-sword, falchion (anti cloth armor) or some kind of saber (\)). Additionally, he´ll need two belts to hold a back mounted, closable quiver for hurling-spears and for lashes holding a collection of throwing weapons or poison darts. These are disposable and kill using poisons. If poisons aren´t widely and cheaply available, either forget about these or upgrade to knives and throwing hatchets. \"Have you seen these warriors from Hammerfell? They got curved swords. Big. Curved. Long........ SWORDS." [source: The Elder Scrolls: Skyrim] [Answer] While the first two commentors already had very good ideas, I'd like to add some more: A double-ended halberd would be useful both for climbing in trees and for combat. It allows usage like a lance, like an axe (for damaging branches, too) and as a grappling hook to offset the balance of your opponent or to grab a branch for climbing or manipulating against an enemy. One side could be simpler (a wooden spear and a hook instead of a heavy axe and spear tip), so it's lighter and can better be thrown (which would only be done when someone is sure to be able to recover it, or in an ermergency when it would be too heavy to carry but might bring down one of the many approaching enemies). A one-ended/normal but short version of a halberd could be the improved sword of the trees. A pick-axe as used by mountain climbers would also work well in trees and could have a normal axe (and hook) on the back. It would be a good short-range weapon - the dagger of the trees. A sword with a tip curved back could serve as a hook, would have more slashing options. Like the other weapons, it could use a leather band to allow hanging from it, so the fingers don't have to carry all the weight of an armed and armored fighter and/or the grip can stay optimised for fighting, not for climbing. A rope can be used to tie down (elastic) branches and release them in different ways to harm approaching enemies. Or to help unroot a few trees between two forests so that enemies have to use the ground. It's also good for ambushes from the side (swinging) or from above, and, with a hook, also from below. As you will be needing your arms more than your feet in the trees, the feet (I assume ape-like feet from the description) can also do more fighting - by attaching claws or pointy shoes with good grip on branches), by just adding some weight for more punch, and such. Tree branches and sufficiently elastic trees can also make catapults or good traps (especially with pointy sticks attached at the end). Something as simple as a shovel can surprise enemies who, used to life in the trees, may not look for fox holes or soil missing around the roots of the trees they are on. ]
[Question] [ I've been working on a fantasy race recently of sentient bipedal salamanders (sorta) and was talking with a friend about them until one of us realised that since they're amphibians they would breathe through their skin, which means they wouldn't have lungs, which means that they wouldn't be able to speak like we do. I'm not entirely against revising their biology to give them lungs, even if rudimentary ones, but I'd like to exhaust my options before I do that. My world also has a magic system which could hypothetically be used to communicate but I'd like to avoid using that as well, since if they could do it who's to say that any random animal couldn't. So yeah, any ideas? [Answer] Marvel, reader! Telmatobius culeus, the Lake Titicaca scrotum frog! [![scrotum frog](https://i.stack.imgur.com/LaSDO.jpg)](https://i.stack.imgur.com/LaSDO.jpg) <https://featuredcreature.com/alright-heres-the-aquatic-scrotum-frog-a-name-and-a-face-you-wont-soon-forget/> Like your creatures, T.culeus breathes through its skin. <https://en.wikipedia.org/wiki/Telmatobius_culeus> > > The Titicaca water frog spends its entire life in oxygen-rich water > that typically is 10–17 °C (50–60 °F). It mainly stays near the bottom > and it does not surface to breathe if the water is well-oxygenated. It > regularly performs "push-ups" to allow water to pass by its large skin > folds, which absorb oxygen. It occurs even in deeper parts of Lake > Titicaca, although the limit is unknown. > > > Hopefully your creatures also have redundant raisin like folds of skin. I am sure they do. The Shar-Pei of sentient salamanders. Where was I? Yes; noise. Many (all?) frog males vocalize to call mates. If you are completely aquatic and don't get up into the air this becomes tricky. T.Culeus has figured out how to vocalize underwater. [Silent sounds in the Andes: underwater vocalizations of three frog species with reduced tympanic middle ears (Anura: Telmatobiidae: Telmatobius)](https://www.researchgate.net/publication/314084856_Silent_sounds_in_the_Andes_underwater_vocalizations_of_three_frog_species_with_reduced_tympanic_middle_ears_Anura_Telmatobiidae_Telmatobius) > > We recorded underwater vocalizations and examined the middle-ear > morphology in three species of Telmatobius with different > lifestyles... Telmatobius culeus (Garman 1876) (fully aquatic, > lacustrine). Males emit underwater calls, which in the three species > are simple and stereotyped; they consist of a repeated train of notes, > with a low fundamental frequency (309–941 Hz). In each of the three > species, the tympanic membrane is absent and the tympanic cavity is > extremely reduced or absent, whereas the opercular system is well > developed. Our data, along with prior knowledge in other species of > anurans, suggest that the species examined here probably perceived > sound through extra-tympanic pathways... > > > So too your aliens. Like the scrotum frog, their ancestors vocalized in the air. When your creatures took to the water, their vocalization apparatus adapted to water use. When they evolved culture and intelligence and language, their underwater vocalization apparatus was ready to serve. [Answer] Humans often breathe through their nose and yet we talk just fine. Fish breathe through their gills and yet make noise through their mouths (underwater, but still relevant). So, the real question is: How do your cretaures eat? If they eat solids, then you need to deal with the gagging/coughing reflex to clear the old food tube (and, if I remember my high school physiology class correctly, you also need to deal with pressure equalization). That means lungs (unless you always use vomit, but all that acid wouldn't be evolutionarily sanguine, ifyouknowwhatImean). Where there are lungs, there is the potential for spoken language. But! If your creatures don't eat solids (for example, nutrients through fluid/skin contact), then you have a problem. To very strictly answer your question, without lungs you cannot have a spoken language. But, if we opt for the more general audible language, then you can [click](https://www.youtube.com/watch?v=W6WO5XabD-s),1 [snap](https://www.youtube.com/watch?v=KuXLbxo9H8I&feature=youtu.be&t=70), [stomp, clap](https://www.youtube.com/watch?v=CX6tKPte33A&feature=youtu.be&t=20), and [fart](https://www.youtube.com/watch?v=DPZ1x_OshAg) your way to all kinds of deep philosophy. We humans make sound with all kinds of body parts. And that begs the second real question: How do your creatures hear? If your creatures have ears, then any method they use to create sound can be used to create language. If they don't have ears (the ability to detect vibration in a gaseous medium), then this really doesn't matter, because your creatures must be capable of detecting something going on with their associate or the conversation will be very short. --- 1 When you listen to the aborigine, listen for the mouth noises. The clicks, snaps, slurps, etc. [Answer] In our human world, languages can be signed via movement of the arms, hands, and fingers (with the latter two communicating the most information) or they can be spoken with air moving up from the lungs, over the vocal cords, and then shaped by the vocal tract. Spoken language can be done without air. Some spoken languages (like the [Khoisan languages](https://en.wikipedia.org/wiki/Khoisan_languages), the clicking language family of Africa) have consonants that involve clicking the tongue in various ways. Others use glottal stops in the throat or higher up in the vocal tract. It would be easy to imagine a human language that did those things and also clicked teeth, smacked lips, or made other noises with the mouth. You say your species is bipedal. Bipedal implies hands that are free to manipulate objects (and likely with some decent dexterity...which may not be a given, but you can add it in). Hands like that can easily be used to articulate a signed language. While you ask in your title for spoken language, you imply other language forms are acceptable, since "magic" is possible. There's no reason why a species might not combine signs and sounds as well. It isn't generally done in human signed languages because those languages evolve in Deaf communities. But even there, the occasional sound comes through. For example, hands and fingers might articulate the structure of words and the mouth sounds could fill in grammar. Think of a language like Hebrew where the root or each word is the consonant sequence and the vowels used to create syllables can change the gender, tense, or part of speech. I can imagine a language where the positions and motions of the hands give the root and the sounds round it out into a full word. [Answer] Crickets make noise by rubbing their legs together. Your species could use this for audial speech. [Answer] Consider the cuttlefish. It has chromatophores in its skin, which allow it to change colour and pattern. It uses a combination of colour change, skin texture change, and posture to communicate. It has a wider variety of signals than most animals, which are restricted to a few sound calls. Visual communication works. Ask any sign language user. It is possible to communicate just using gestures. If we had evolved from cuttlefish we would be able to communicate using the patterns on our skin. Let us suppose your alien is silent, and has no hearing or vocal apparatus at all. But it can communicate by the patterns that appear on its body. Visual communication is very different from aural communication, if you ask a sign language user you will find that it has advantages and disadvantages. One advantage is bandwidth. It would be possible to communicate more rapidly if we were not restricted by the articulation and interpretation of sound. Think how it is possible to scan-read a whole page of text much faster than you could have it spoken to you. But undirected communication becomes harder. It is difficult to get someone's attention if you can't shout at them. This has a whole lot of social impacts that you would have to think out. [Answer] You may try to use a fast-twitching muscle that vibrates fast enough to make a biological version of a microphone. The muscle may be located under the skin. You may describe evolutionary reasons for its desired location. Maybe on the back, or shoulders? ]
[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/131221/edit). Closed 5 years ago. [Improve this question](/posts/131221/edit) How to explain the fact that unicorns only let virgins ride them? Why does the unicorn even care if the rider is a virgin or not? And why do bicorns do exactly the opposite? Bicorns won't let any virgin ride them. Those two creatures externally resemble horses with horns on the forehead. They are not necessarily normal horses or related to horses but they are still restricted by biological limits, no magic involved. [Answer] This is a misconception that has arisen from a mix of superstition, folklore and pseudo-science. Also some back-and-forth between languages. In English there are distinct words for virgin and virgo. In some latin languages, though, there is just one word for both. It was said that unicorns would only let virgos ride them; when the tale made it into English speaking countries the whole thing was mistranslated. Why virgos? Astrology has it that each zodiacal sign comes with some personality traits. Those born under virgo are neat, orderly and trim. You may not believe in astrology, but the people who came up with the myth did. And as it turns out, unicorns are very virgo-ish. They will not walk on mud, and they will not allow themselves to be ridden by people who they perceive as unclean, such as being covered in soot or dirt. So... In ancient times, when people would bathe once a year and most people believed in astrology, people would say it would take a virgo to ride a unicorn. When the myth reached UK, people mistranslated it, and now people think it takes an intact hymen to ride them 'corns. Bicorns, on the other hand, like to roll on the mud. They also cover their legs in feces for thermal regulation. For astrologers, no virgo would ever ride them. For people with common sense, no one would ride them unless they are ok with needing a few baths later. Again, the myth got a whole new spin in English due to a mistranslation. P.s.: this is not the original version of the myth, it's just something I came up with for this question. [Answer] 1. Unicorns (I've edited to include bicorns) This is actually a myth but a pervasive one and partially based on fact In the old days there were no horse-whisperers - horses were 'broken' to the saddle. The wild unicorn simply would not submit to being broken - it would behave like a bucking bronco in a rodeo. From exhaustion it might temporarily submit (but stand still and refuse to move forward). On recovering its strength it would be completely intractable again. Horse breakers were predominantly men. The unicorn detects their maleness by its exquisite sense of smell. It can detect testosterone and indeed the slightest trace of semen. In general married women found little or no success in training them, firstly because they tended to use the same methods as men - namely 'breaking'. Also because of the likely scent of semen however faint. (Hygiene standards were low in those days so people didn't tend to wash their private parts). Virgins had neither large amounts of testosterone nor traces of semen. They also tended to be small because in those days marriage could take place at puberty. Young girls are known to have an affinity for horses (these days manifested in My Little Pony) and are likely to tame by kindness and affection. One such little girl discovered her ability by accident when she encountered a unicorn in the forest. She felt no fear and had no concept of breaking a horse. She was able to interact with and even ride the unicorn. She ran back to tell her friends and parents and the myth arose from there. Thereafter virgins were used in any dealings with unicorns that required them to be tamed or even ridden. EDIT In response to a comment: "...in the old days there were no separate bedrooms. If there was a bed, it was for everybody in family. So I would hardly say that virgins had no male odor on them. ‚Äì L.Dutch" My reply It could be that unicorns mainly frequented the royal forests because they were protected from poaching there. The only virgins that encountered them would be daughters of nobles and would likely have a separate bedchamber and handmaid if only to obey the dictum, "Children should be seen and not heard". Note: Even royal hygiene was hit and miss at that time however pre-puberty there is little B.O. of any kind. P.S. This raises the question of whether virgin boys would qualify. Maybe they would but I suspect that they would be brought up in a male tradition of hunting or subduing forest creatures rather than being kind to them. --- 2. Bicorns > > The Bicorn is a creature (often described as a part-panther, part-cow creature with a human-like face[1]) that has the reputation of > devouring kind-hearted and devoted husbands > <https://en.wikipedia.org/wiki/Bicorn_and_Chichevache> > > > The obvious answer is that bicorns refuse to let almost anyone ride them. All they are interested in is devouring kind-hearted husbands. Maybe they beguile men to ride them and then after a suitable interview to determine whether they are kind-hearted or not, stab them with their horns in a backward movement or throw them off accordingly. [Answer] Sensing virginity is an innate ability that members of the unicorn family have Unicorns, like many animals, mate for life. They invest a tremendous amount of effort raising their young, and their courtship rituals aren't just a wonder to behold, they also occupy a significant portion of each unicorn's lifespan. Unicorns have a few magical abilities, but in terms of them breeding there are only three that matter: their impressive glamour display which they use to woo potential partners, their ability to sense whether a unicorn is their own offspring, and their ability to tell whether or not a potential partner is a virgin. Due to male unicorn's unfortunate habit of killing their rivals' offspring, a tendency to avoid non-virgin (except for their partner) unicorns was selected for. A side effect is that unicorns also avoid humans who are not virgins. Bicorns have similar abilities, but live in radically different conditions. Due to the hazardous terrain, partners will often die young, so the willingness to switch partners is more advantageous. In addition, circulating among the bicorns is a strain of Equine Magical-Deficiency Virus, which causes them to appear as if they are still virgin. Because of this, bicorns have the opposite tendency to unicorns. ]
[Question] [ I have a super-earth world. The surface of the world is shallower due to extra gravity, so shorter mountain ranges and less ocean depths. The world orbits a binary star system at a distance of the furthest region of the habitable zone, both of the stars having masses of 0.93x that of our suns. The world is highly volcanic, approximately 15 to 16 times more volcanic than our planet. Surface gravity: 1.35x of Earths. Atmosphere thickness: 10x of Earths (a result of it being highly volcanic in comparison to earth.) Atmospheric composition: Nitrogen 78%, 15% Oxygen, 5% Carbon dioxide, 2% Trace gases. Temperature: rather hot, the tropical regions being 90 to 110 degrees Fahrenheit. (based on what I've tested on Universe Sandbox 2) Land coverage: 75% water, and 25% land (but less water being present on this world as the oceans oceans are shallower mostly due to a lot of island formations) Radius: 7750 kilometers Day/Night length/full rotation: 28 hours. Axial tilt: 53 degrees. Orbital period: 1.15 years Eccentricity: 0.025 --- How would the fauna and the flora of this particular world be due to its pressure? [Answer] # TL;DR Your fauna: * Oxygen concentration is lethal for Earth's life due to oxygen toxicity at high values. Your creatures will need a lot of evolution to survive there. * Will have short lifespans with a lot of offspring due to damages produced by the high oxygen concentration that can't be fixed. * Insects will be huge because they're breathing through their skin and that produces a fine relation between surface/volume ratio and oxygen concentration. * All your fauna will suffer nitrogen narcosis which is quite similar to being drunk. You will need some evolution in their nervous system. * Bacteria will have more nitrogen to breathe and use to make aminoacids, with that proteins and with that plants and animals. It'll be quicker and easier. * All fauna will suffer hypercapnia, respiratory acidosis due to carbonic acid and carbon dioxide toxicity at high concentration. If you don't have a massive rework at the acid level of their organism they will die. * Water will become acid due to CO2, that will kill a lot of fauna in water, like coral and others. * Their deaths will reduce the planetary albedo and that will raise the temperature. * CO2 is a greenhouse gas and it will seriously increase the global temperature a lot of degrees. Your flora: * [An increase of carbon dioxide and nitrogen could aid the photosynthesis of plants increasing their grow rate](https://www.scientificamerican.com/article/ask-the-experts-does-rising-co2-benefit-plants1/). But you will have to explain why plants has already consumed all that CO2. Our atmosphere has $101.325 \text{ kPa}$ of pressure. Your world: $$101.325 \text{ kPa} \times 10 = 1013.25 \text{ kPa} = 1.01325 \text{ MPa}$$ * 15% O2. * 5% CO2. * 83% N2. Now, I'll show you the partial pressure of that gases. $$\begin{array}{\|cr\|ccc\|r\|} \hline \text{Chemical} & & \text{gr/mol} & \text{Mols} & \text{Fractal Mol} & \text{Partial Pressure} \\ \text{O}\_2 & 15\% & 31.9988 & 0.4687 & 0.1363 & 138.14 \text{ kPa} \\ \hline \text{N}\_2 & 80\% & 28.0134 & 2.8557 & 0.8306 & 841.61 \text{ kPa} \\ \hline \text{CO}\_2 & 5\% & 44.0099 & 0.1136 & 0.0330 & 33.48 \text{ kPa} \\ \hline \textbf{Total} & 100\% & 104.02 & 3.44 & 1 & 1013.25 \text{ kPa} \\ \hline \end{array}$$ Let's start with the analysis! ## Extremely hiper-lethal O2 You have more than 138.14 kPa of oxygen! That is too much. On Earth we have around 21 kPa of O2. Any value above 50 kPa becomes lethal to humans (and the majority of animals) due to [oxygen toxicity](https://en.wikipedia.org/wiki/Oxygen_toxicity) that produces [hyperoxia](https://en.wikipedia.org/wiki/Hyperoxia). In [this answer](https://worldbuilding.stackexchange.com/a/85096/35041) I enumerate the symptoms of oxygen toxicity. [![different problems that arise from a high oxygen concentration](https://i.stack.imgur.com/7CBF1.png)](https://i.stack.imgur.com/7CBF1.png) These are some of the major damages produces by hyperoxia. All your fauna must to find a way to combat this issues, you should ask into another question about how to combat just the oxygen pressure. Also, the increase of oxygen pressure will increase the oxidation speed of stuff (like metals) and even organic matter (like when an apple becomes darker after you cut it) and also will make things much more flammable. The increase in oxygen pressure will increase the amount of [ROS](https://en.wikipedia.org/wiki/Reactive_oxygen_species) in the air. Reactive Oxygen Species produces enormous [damages](https://en.wikipedia.org/wiki/Reactive_oxygen_species#Damaging_effects) in our body at a molecular level, like: * Damages in the [electron transport chain](https://en.wikipedia.org/wiki/Electron_transport_chain) of [mitochondrias](https://en.wikipedia.org/wiki/Mitochondria) (which produces our energy). * Lipids and proteins, which compound us. * And DNA and RNA which we use to carry our genetic information. All these accumulative damages produce an [oxidative stress](https://en.wikipedia.org/wiki/Oxidative_stress), which increases our [ageing](https://en.wikipedia.org/wiki/Aging) speed due to the non-healable produced damages in our cells. Your fauna will have shorter lifespans and a lot of offspring (if they survive) because maintaining an old organism in this environment is really difficult due to the constant damages. The majority of these damages (for example retinal or skin damages aren't included) could be reduced by some evolution in their respiratory systems. I mean, if by some way you are able to reduce the oxygen input, all the damages in their inner organism could be avoided. * A way to do that is by an [active transport](https://en.wikipedia.org/wiki/Active_transport) in the cells membranes. Sadly that is impossible because it consumes ATP (energy) in order to maintain it, and the idea of breathing it to get energy, not consume it. * Another way could be with a [semipermeable membran](https://en.wikipedia.org/wiki/Semipermeable_membrane) where oxygen is only allowed when there are low values in the body, but at high values, it's blocking the passage. I'm not sure if this is possible to achieve with oxygen. [In this answer](https://worldbuilding.stackexchange.com/a/82850/35041) I explain another effect of an increase in oxygen levels. Also, another effect on animals will be produced, and I explain that [in this answer](https://worldbuilding.stackexchange.com/a/85096/35041). Have you seen ever this [terrifying creature](https://es.wikipedia.org/wiki/Theraphosa_blondi)? Luckily, I've never seen one, but sadly in your world, there will be nothing compared to your insects, because they will be extremely big. Insects don't have a respiratory system. They breathe through their skin, so if you make them bigger they won't have enough cm2 of surface per gramme of `insect`. They will suffocate (because of surface/volume ratio decrease per size). On your planet there is \\a lot of oxygen in air\* so insects could be a lot bigger without suffocating. \* Insects have a respiratory system, but they don't have lungs or gills, they use other [things](https://en.wikipedia.org/wiki/Insect#Respiratory_system). On the good side, you could think that your fauna will have more oxygen to use, which means a faster metabolism. ## Really very high N2 Your N2 value is 841.61 kPa. At values above 400 kPa [nitrogen narcosis](https://en.wikipedia.org/wiki/Nitrogen_narcosis) appear. Nitrogen narcosis is quite similar to the effects of alcohol's [drunkenness](https://en.wikipedia.org/wiki/Drunkenness), cannabis, [nitrous oxide](https://en.wikipedia.org/wiki/Nitrous_oxide) breathing or drugs from the [benzodiazepine](https://en.wikipedia.org/wiki/Benzodiazepine) family as [diazepam](https://en.wikipedia.org/wiki/Diazepam) or [alprazolam](https://en.wikipedia.org/wiki/Alprazolam). * It produces anxiety, a feeling of tranquility, a mastery of the environment. * It means losing the ability to recognize danger, impairment of judgement, multi-tasking and coordination, loss of decision-making ability and focus. * Vertigo and visual or auditory disturbances. * The syndrome may also cause exhilaration, giddiness, extreme anxiety, depression, paranoia. * More serious (not sure if your case) overconfidence, slowed mental activity, increased reaction time and errors in cognitive functions. * Reduction of both the perception of cold discomfort and shivering and thereby affects the production of body heat. At your pressure, it can be "barely" compared to drinking 7 consecutive martinis...[citation needed] Again, the solution may be something similar to the lungs evolution of oxygen or some kind evolution in the neural system: > > Modern theories have suggested that inert gases dissolving in the lipid bilayer of cell membranes cause narcosis. More recently, researchers have been looking at neurotransmitter receptor protein mechanisms as a possible cause of narcosis. > > [...] > > The precise mechanism is not well understood, but it appears to be the direct effect of gas dissolving into nerve membranes and causing a temporary disruption in nerve transmissions. > > [...] > > Similar to the mechanism of ethanol's effect, the increase of gas dissolved in nerve cell membranes may cause altered ion permeability properties of the neural cells' lipid bilayers. [...] > > > On the good side, bacterias breath N2 and make aminoacids with them. Aminoacids are used to build proteins and they are used by plants and animals. More nitrogen in the air will make this faster and easier. Also [an increase of carbon dioxide and nitrogen could aid the photosynthesis of plants increasing their grow rate](https://www.scientificamerican.com/article/ask-the-experts-does-rising-co2-benefit-plants1/). ## Extremelly lethal CO2 Your CO2 partial pressure is 33.48 kPa. [In this answer](https://worldbuilding.stackexchange.com/a/82850/35041) I explain the increase of CO2 by just a bit. * [Hypercapnia](https://en.wikipedia.org/wiki/Hypercapnia), production of [carbonic acid](https://en.wikipedia.org/wiki/Carbonic_acid) and [respiratory acidosis](https://en.wikipedia.org/wiki/Respiratory_acidosis), and [carbon dioxide toxicity](https://en.wikipedia.org/wiki/Carbon_dioxide#Toxicity). Any value above 10 kpa (you have 33.48 kPa) produces hypercapnia and acidosis. [![carbon dioxide toxicity explained with respect to different parts of the human anatomy](https://i.stack.imgur.com/Rx0Cu.png)](https://i.stack.imgur.com/Rx0Cu.png) [In this answer](https://worldbuilding.stackexchange.com/a/84125/35041) I explain in deep symptoms of hypercapnia. There you will note a table which says that a 5% CO2 concentration could kill you in 4 hours, at normal partial pressure, for you, it's a matter of minutes. The worst part is that you can't just breath less in order to avoid it, because hypercapnia is matter of expel CO2, not breath it, and due your partial pressure it's impossible to get rid of it. * Increase the acidity of lakes and oceans because CO2 combines with water and become this acid. All your submarine fauna will cry. + All your coral will die of starvation because they will expect a reduction of 90% in their [energy input](https://en.wikipedia.org/wiki/Zooxanthellae) due to [coral bleaching](https://en.wikipedia.org/wiki/Coral_bleaching). - Their dissolved white Calcium Carbonate (CaCO3) shells from their corpses will disappear and that would reduce the [albedo](https://en.wikipedia.org/wiki/Albedo) of your planet, effectively increasing global temperature. * CO2 is one of the [greenhouse gas](https://en.wikipedia.org/wiki/Greenhouse_gas) which increase the global temperature of Earth. I don't want to do any calculation about it, but I'm quite sure it would increase several degrees the temperature, maybe 15 ºC or even much more, you have a lot of CO2 and a lot of pressure. Rember that CO2 is the second (9% - 26%) dangerous gas in the global warming. * CO2 is an [asphyxiant gas](https://en.wikipedia.org/wiki/Asphyxiant_gas) and due to its higher molar mass compared to oxygen and nitrogen it may get sink in valleys, where the concentration is much higher than in other places, if there is no wind. Your fauna must be able to hold a higher acid value in their organism, not sure how. On the other hand, as a good side, [an increase of carbon dioxide and nitrogen could aid the photosynthesis of plants increasing their grow rate](https://www.scientificamerican.com/article/ask-the-experts-does-rising-co2-benefit-plants1/). * That means you will have to explain why plants haven't already consumed all this CO2. CO2 must be replenished by a huge amount of fauna or by an active process like volcanoes. ]
[Question] [ Okay, not literally Krypton style, but let's say some local astronomical event is going to render every rocky surface in our solar system totally uninhabitable. Details aren't terribly important, so let's just say every planet is going to fall into the sun for some reason. We have... an amount of time before it's going to happen (let's say around ten years), and that before it happens, the earth (and everything else in our solar system) is going to be just as habitable as it currently is. Also, we have recently received very convincing (and convenient) evidence that there is an earth-like world in a neighboring star system, with, shockingly, an oxygen rich atmosphere and a functioning biosphere (how we got this evidence is also irrelevant, so for fun we'll say an alien robotic probe told us about it before scooting out of the system). So, the question is, can the human race build a ship capable of restarting the human species (if not the civilization) on that nearby planet? Some other simplifications/freebies: * Human society works out in such a way that at the very least our efforts aren't severely impeded. * Only current or very near current technologies are allowed. * One "freebie" technology is permitted, with the caveat that it can only be something which theoretically we can probably make, but simply haven't put the effort into making (I have a few candidates in mind, but I don't want to bias your answer). [Answer] # Elon Musk to the Rescue If you asked this same question 10 years ago, I would be as pessimistic as many of the other answers. But this is 2018. The [Faclcon Heavy](https://en.wikipedia.org/wiki/Falcon_Heavy) is in production. The [BFR](https://en.wikipedia.org/wiki/BFR_(rocket)) is on the way. Elon Musk has, many times, said that his goal is to establish an outpost on Mars to save humanity. # Sleepers One "freebie" technology? That would have to be suspended animation (and I don't mean canceling the Flintstones). It is not as far away as you might think. I don't think it could make us live forever, but if we can sleep through the trip and wake up when we get there then we can save a lot of payload otherwise needed for food, water, medicine, etc. If this is a 100-year journey (using [Project Longshot](https://en.wikipedia.org/wiki/Project_Longshot) as a starting point) and we have sleeper technology that gives us 100:1 metabolic processing then the human bodies will have effectively aged only 1 year (so they are still "young" when they get to the destination) and the nutrients consumed would be equivalent to 1 year - not far off from what a BFR would need to take for a Mars trip. While sleepers would need extra equipment to keep them fed, healthy & safe, they would need essentially crowded bunk space but no common areas, exercise rooms, etc. and all the extra payload space & weight could be devoted to equipment needed on arrival. Unlike one book I read (can't remember the name at the moment), we need to make sure everyone sleeps through - if one person wakes up 1/2-way through and can't go back to sleep then he would eat (in 50 years) 1/2 the food intended to get all 100 people through the first year on the new planet. # How many can we save? We can't save everyone. But we can easily save thousands. The key is using BFR to get things in orbit and assembling, in a minimalist fashion, in orbit. The main BFR is designed to be fast-reusable, which is a key. Something like: * 19 BFR flights for a 3-level hexagonal ship - 1 in center, 6 in 2nd level, 12 in 3rd level. Inner 2 levels have 200 sleepers each = 1,400 people. Outer level filled with food for the first year at the destination and equipment to set up a small colony - water purification, seeds, medicines & medical equipment, computers, tools, solar panels, Teslas, etc. Outer level also provides radiation shielding for the inner levels. * 8 BFR flights for a propulsion module. 1 in center to separate this from the main section (not sure this is needed but it is a common style of ship in many sci-fi novels), 7 in 2-level hexagon - center for propulsion (ion? fusion?) and 6 for fuel (reaction mass, not ordinary rocket fuel) That is a total of 27 BFR flights per 1,400 people. SpaceX, with some BIG government help (remember, so far SpaceX has done the bulk of its development using some government funding but primarily funded by paid commercial, government and military flights and private investment) gets the BFR assembly line running at [Liberty Ship](https://en.wikipedia.org/wiki/Liberty_ship) speed then we get BFR serial production within 2 years, with ship (sleeper, cargo, propulsion) design running simultaneously. Assuming BFRs can get a weekly refurbish rate and 100 (= 2 years) uses per BFR before retirement (while major overhaul might make sense, I'll assume some occasional damage-beyond-practical repair, plus the production line for new BFRs will make major overhaul less cost-effective), that would mean a total fleet of ~ 60 BFRs but won't have full launch cadence until ~ 30 have been produced. So early production will be key. On the other hand, the starship components will be needed at a steady 2 per day throughout the launch window. Start with the equipment & fuel modules. Sleeper modules would go up last to give those people maximum time on Earth - last 2 years would be almost all sleepers. With 4 launch pads (2 Florida, 1 Texas, 1 California) running on an alternate-day basis (try for daily but there will always be some days you can't launch due to weather, delays in payload processing, etc.) that would be (2 per day \* 365 days \* 8 years) / 27 per ship \* 1,400 people per ship = 302,814 people. Figure 10% loss due to ships not completing the journey due to mechanical failures, 10% loss of sleepers due to problems "waking up" and you've still got 245,279 - a quarter million people is a nice large genetic pool to restart humanity. [Answer] There is a reasonable chance of success. Definitely not a sure thing. We need to use the most effective rocket propulsion that we know of and within our capabilities and resurrect [Project Orion](https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion)) Since your propulsion system is a large number of nuclear bombs, this is not generally considered an ideal propulsion system, but if it the only option, it is a dandy system - who cares about the environmental damage and political consequences. BTW, the actual damage from fallout is a lot less than most people would expect. This system has been studied in surprising detail, and it turns out you need about 800 bombs to obtain earth orbit - mostly independent of the size of your spacecraft. For high speed interstellar flight (133 years to Alpha Centauri), you need quite a lot more bombs (on the order of millions). You can also launch a huge payload - such as a city. A number of different designs to meet different needs have been proposed. We will need a lot more bombs, as well as the ship itself. But with everything in full-on rush mode, it is conceivable. The United States, and several other countries are already wealthy enough to build such a vehicle. Given the large mass allotment, you can scale up to add the heavy shielding needed to protect from radiation in space, and possibly an ecosystem complete enough to survive the long trip. Dealing with long-term micro-gravity would also be a major issue, so spinning up your ship needs to be added to the design. Compared to typical spacecraft, Orion is a simple design which bodes well for a crash program to succeed. There is a lot to do, and much we don't know, but a reasonable chance is better than certain death. I fear that a reasonable chance in this case may be something like 10% or even 1% -- yeah that's lousy odds. But you should not wait until 10 years left before you start building your interstellar space ship. Re: the free technology -- I would ask for the ecology package to get the in-flight environment stable and healthy -- we have had no success in doing this well yet.. [Answer] Maybe. In 10 years? Probably not. Right, so first off there isn't a lot that can destroy every rocky world. You said don't worry about it but it'd probably affect the answer a bit. I'll do my best to ignore it. Whatever it is, a catastrophe of this magnitude make humanity quite irrelevant. We for sure can't stop it. The only solution is to leave. This is maybe at the very edge of human possibility. Maybe. First, we'd need to get people there. This is a lot easier with hibernation technology but I think that's kind of cheating and not as important as shields, so that's my freebie technology. Ion shield technology is in very early stages here on earth but it'll be essential for life. So, we have a way to protect people from radiation in space. First part done. Next is the ship itself. It'll be big. It'll need to rotate in space to provide gravity; zero-g is too damaging to have people in it for such a long trip. However, to achieve 1g without motion sickness it needs to be a big ring. Inside it'll need hydroponic farms, living quarters, recreational areas, medical facilities, embryo storage, maintenance areas, water purification, power generation, shielding, armour, and a hundred other areas to make this just livable. A small crew raising the next generation of embryos to take over is the best option. Keeps genetic diversity and when they reach the planet, gives them an easy method of populating it again. Propulsion is difficult. Best option is nuclear propulsion: put simply, you blow up an atomic bomb right behind the ship and it pushes it along. That we have within a reasonable time frame. Best though would be fusion rockets. The fuel is difficult to come by but the trip would be around 40 years. That'd simplify things quite a lot as it would be a single generation ship. Most importantly of all though, you wouldn't send one ship. You'd send as many as you can, staggered as much as possible to prevent them from being destroyed. Shotgun it. Got nothing to lose. The problem is the time frame. 10 years, in the scale of such an engineering project, is really really short. 100 I'd say we definitely attempt it a few times. 10? Hard to say. Maybe we get a few cobbled-together ships up there, but it won't be easy. [Answer] 10 years? Don't bother trying. With near-future technology the best we can hope for is a fusion version of Orion. A reasonable estimate of the ISP of a fusion Orion is [about 7,500](http://www.projectrho.com/public_html/rocket/enginelist.php). That's roughly 15 times as good as the best chemical engines. Thus you're looking at roughly 15x the delta-v we have managed to put on a manned rocket--Apollo. It had about 18km/sec, so with the same mass ratio we are looking at 270km/sec. Figure 24km/sec from the surface to solar escape. Another 13km/sec for capture, thus leaving 233km/sec for the trip. That means you're cruising at 116km/sec. That's 116 centuries in flight to Alpha Centauri. [Answer] The National Geographic documentary "Evacuate Earth" gave us a doomsday scenario of a Neutron star on its course to hit Earth in 75 years. Even with such an advance to realize ONE generational ship, escapees made it at the last moment, what between riots, defections, suicides, increasing catastrophes, etc. 10 years? In an even more hurry. Orion cannot be built on Earth, you must do it into space. which means USA, Russia, China, EU, India, Japan, Australia, will have to launch and launch and launch materials, keep their austronauts working to an extremely stressful clock, letting them understand that perhaps not all of them or their families will leave Earth. Riots and wars will spread to get a ticket to safety. Mass exterminations will occur. The candidates will have to be protected 24/7, that is, unless the very guards break down and take the candidates as hostages to get a ticket themselves. Terrorists and religious zealots will have no trouble convincing hysterical masses to sabotage the efforts by cutting lines of resupplments to the project. And not to mention plain accidents. You can't do all of this, even in the best conditions and not expect accidents to interfere with the schedule. Two Space Shuttles were destroyed because of...what? A tiny leak in the components, a crack here, and boom! you lose a crew of specialists and a reusable transportation. And you MUST reuse as long as possible since the industries in the world will be under catastrophic pressure to build components for the Ark. Let's just take the weather: window launches for rockets requires certain meterological conditions, and you can't just come up with innuendo launch stations. Delays will be unavoidable even on that front. And the more time passes, the more pressure is exerted on the staff and the crew. Medical staff will skip one simple routine procedure with their astronauts, sicknesses set in, more losses. The candidates will start panicking. They are essentially prisoners, they cannot leave the evacuation point's premises -in fact, it would be dangerous even to let them walk around unguarded. Many one candidates will get nervous brackdown or just commit suicide or refuse to leave in order to stay home as doubts creep in deeper and deeper. Nah, 10 years is not enough. EDIT AS PER MISTAKEFULLY READING THE QUESTION: Since the Ark is a gigantic, untested prototype, and such a complex titan that is supposed to host human survivors, seeds, DNA from at least farm animals and enough human DNA to grant reproduction without inbreeding, is likely to suffer system crashes during its travel. Nuclear propulsion, the only more reliable propulsion technology (and energy generations for the ship's needs) at this point of the story, [would use 1,000 years only to reach Proxima Centauri B](https://www.astronomytrek.com/how-long-would-a-spacecraft-take-to-reach-proxima-centauri/). My suggestion is that that convenient planet is located around that sun. It's difficult to imagine the survival of the species in such conditions beyond this limit. In fact, in 1,000 years, arriving to Proxima would be nothing short of a miracle [Answer] Many have highlighted that there is a problem with technology and sociology. I'd like to mention a problem with physics. # We can't flee that fast So, by definition of the problem, the whole Solar system is scorched off by some kind of a mega Solar flare or something. This means that * we cannot run to Mars, as it won't help. It was not stated in the question for how long the scorching continues and how fast does it advance. But my point is that our current space faring is quite slow and non linear. Assume that the flare takes one year to propagate. (It's a guess, but the radius of the solar system to the edge of the last still-planet is around 4 light hours.) * We cannot run away fast enough. Any kind of propulsion known to us would not accelerate the ship fast enough to outrun the wave, even if we start early. Even worse, * We don't run strait. All space navigation either requires orders of magnitude more energy, or (our option) slides along the gravitational vortices and makes use of cunning (and very curved) transfer orbits. The flare travels linearly, though. --- One of better options is research on how deep the flare would burn. Given that it is stated to scorch down stone in every planet in solar system, we would probably loose the atmosphere anyway. But maybe burring few kilometers down would help, who knows? The second option is to boost research on strong AI and non-quantum teleportation (maybe even using the strong AI), as our only feasible option to live is to warp away. I also forsee a lot of projects similar to "let's beam our DNA per radio into the space" in a futile attempt to leave some legacy. [Answer] The only way I could see us being able to travel through space for thousands of years with current or near current 'human technology' is for us to turn all of our attention towards creating an [Artificial Super Intelligence (ASI)](https://harvardsciencereview.com/2015/12/04/artificial-superintelligence-the-coming-revolution-2/) and allow it to figure out and build a ship for us to travel on. Or it would figure out how to stop the impending doom about to befall us all. As long as we could harness the ASI to do our bidding it would be able to essentially figure everything out (given enough time and computing power - all countries would have to bring their [supercomputers](https://www.theverge.com/circuitbreaker/2018/6/12/17453918/ibm-summit-worlds-fastest-supercomputer-america-department-of-energy) together to make it happen - a good way to ensure countries work together.) It would devise propulsion, shields, food, water, power, etc. It would have to mine the world with robots it created. An ASI would basically be able to figure out and do anything that is physically possible. Since we're all going to die from the 'event' anyway, the fears of an ASI destroying humanity would be worth the risk and would also make for great suspense. Perhaps the first few AIs were killed before they could get to the ASI state because they became [violent](https://www.theverge.com/2018/6/7/17437454/mit-ai-psychopathic-reddit-data-algorithmic-bias) or destructive. The reader wouldn't know which way you're going to take the story. Will we live or die? If we die is it from the ASI or the 'event' because either we couldn't make the ASI in time, or we made it and it couldn't get the ships done in time. Would the ASI be able to come? Would it be too big and consume too much power to make the journey? Would it have a sympathetic personality that makes the audience feel sad that it got left behind after helping us get off the planet? Other than that, or aliens, I don't see how it is possible to build a sustainable and pilotable biosphere for the thousands of years it would take to get to the new Earth. [Answer] @TracyCramer's idea is a good start but with a ten year deadline, even an Artificial Super Intelligence would be hard pressed to save humanity. So the better solution is to NOT save humanity. Just save our genes. Create Tracy's ASI and ask it to focus on creating a ship capable of carrying itself to the new world. It can take its time getting there and won't need a lot of oxygen or water to survive the trip, so getting it launched on time is reasonably doable. We might even get a few redundant copies of the ASI launched in separate ships just to increase their survival odds. Then when one of the ships gets to the new world, have the ASI develop artificial womb technology and synthesize fertile human embryos out of spare bits of carbon found on the new world. It might take a billion years for it to get all the bugs worked out but eventually humans would walk on this new world. [Answer] 10 years is about the time it took to develop the American lunar program, which was far from "let a bunch of humans survive thousands of years in the hostile space and then finally colonize a planet". The hurdles which will kill this project, requiring more than 10 years to be solved: * propulsion: the delta v we can squeeze out of our rocket doesn't allow us to ship large masses into space. We could use gravitational assists from Jupiter and Saturn maybe, but at the price of further lengthening the travel. * survival in space: as far as we know now, we are not suited for living in space. Radiation and lack of gravity are serious issues, and again we are mass limited. * colonization: all the colonies we set up during our history were heavily reliant on the mother nation during their beginning. Being literally on your own in a hostile environment simply pumps up your chances of failure. One could say "we can ship frozen embryos with automated life support and hope for the best". Well, aside from consideration on exposing an embryo to cosmic radiation, it is well known that human babies need human contact during their infancy for a proper development, and robotic assistance is way too far from supplying it. ]
[Question] [ (To specify, it doesn't have to be specifically a crossbow, if you can think of another weapon that can fulfill the same job like a speargun or a harpoon, or even just a regular bow you're welcome to suggest them as well) So, long story short, ice bullets are too lightweight to function, as various answers on this site and others have explained. But what about a bolt sculpted from ice? (or a spear or harpoon, see above) Would a bolt sculpted from ice and fired from a modern crossbow be enough to kill a person? Let's assume it's a highly trained assassin firing the weapon, so they can hit vulnerable parts of the body like the throat or jugular if need be. EDIT 2: It just occurred to me that not everyone might be clear on why I'm looking for Ice-based Weaponry. It's the same reason behind the need for Ice Bullets. The reason is that these arrows will (theoretically) dissolve in the body of the target, leaving no way to determine that they were shot. I'm really sorry I didn't notice this earlier, although it looks like I caught it early enough that no one gave any answers that didn't answer my question. Edited title because I didn't want people thinking the crossbow itself was made of ice [Answer] Ice is really too brittle to make weapons from easily but by adding wood pulp you can make [pykrete](https://en.wikipedia.org/wiki/Pykrete) which produces a stronger end product. If it should melt, you're left with mushy paper Pykcrete can be used to make knives and other pointed weapons capable of stabbing someone without shattering. It won't hold together like metal but will hold together enough to get the job done. [Answer] Making bolts or arrows out of ice is not a good idea, the arrows could break under the strength of the crossbow, because the force has to come from the back of the projectile to the tip, that produces vibrations and bending. The long thin shape of an arrow is not optimal for these reasons, and it is the projectile that modern crossbows use. Arrows also need fletching, that you can not make from ice, because it needs to be flexible at least a bit. The smaller thicker bolt could work, but the kill would still not be guaranteed, since it could break easily if it hits bone, because you have fairly thin point made from a very brittle material. You could compensate for the vibrations with a tube, or go full Slingshot channel and use pressurized gas to propel the projectile. BUT have no fear, for I have found a different solution, that still uses ice projectiles and crossbows. But they are nolonger sharp and pointy. The answer to this problem is quite simple. Shoot hailstones instead of icycles. You get lots of ice bullets and [this type of crossbow](https://en.wikipedia.org/wiki/Bullet-shooting_crossbow). Round projectiles are ideal even for a brittle material like ice. Hailstones have good aerodynamics (all round things have), they are heavy, they withstand the shooting as well as the impact.(as proven many times in nature) In nature they still do some harm, but if you use a crossbow, you can propel them far past their terminal velocity. This projectile also doesn't lose its functionality if it's in a warm environment, yes it will melt eventually, but while it still has enough weight it will work just fine, while the arrows and bolts will become dull. But even this projectile can be very light compared to the intended ammunition (lead), so unless you have a very powerful crossbow, don't expect good range or accuracy. If you want to make the bullets somewhat pointy, you could use a tear shape, like on sling bullets. [Answer] Falling icicles can and do kill people. (With greater regularity than I thought, based on multiple news sites I found online, like this one from Chicago <https://www.citylab.com/environment/2012/02/chicagoans-vs-falling-icicles-history/1219/> ). So, yes, projectile ice can kill people. The question is one of firing speed and weight. Can you fire the crossbow from height? The acceleration by gravity would help. Also, most of the killers are in the 5 to 2-to-4 kg range. A typical wood arrow is around 18 g according to Wikipedia. That’s going to take a pretty massive crossbow. So I think the answer is likely “no.” [Answer] Go back to Pre-History.... The Atl-Atl From long long ago, many cultures across the world used a variety of [spear throwers](https://en.wikipedia.org/wiki/Spear-thrower) in warfare all the way up to Aztecs battling Spaniards. The concept is simple. Use something to add length your trowing arm and launch a projectile. The concept is even out there today in those ball throwing things you can buy for your dog. The Meso-American version was basically a stick with a cup or hook on one end, a handle at the other. They loaded it with a spear or a dart. With and overhand throwing motion the dart was propelled forward and the mechanical advantage provided by the launcher made the projectile fly farther and faster. It couldn't affect Spanish plate armor, but it was hell on mail and cloth armors. How would this work for you? You could go in a couple of ways. One of them is to create a spear about 2 or 3 feet long. I'm reasonably certain that a 3 cm shaft around 60 or 70 cm long and only sharpened along the last 3 cm or so would hold together and have enough mass to be lethal over 30 meters or so. If your test of the ice spear doesn't work out, freeze spheres of water and get into the sport of [Jai Alai](https://en.wikipedia.org/wiki/Jai_alai). That game has a thrower that operates on very much the same theory as and AtlAtl. The ball moves at speeds approaching 290 KpH! A 5cm radius sphere will weigh about 1 kg (check my math, it's been a long time since geometry). So if kinetic energy is 1/2 \* mass \* velocity squared, that means a 1 kilogram ice ball moving that fast is going to have 3200 Joules. The energy from a .45 ACP bullet is around 477 Joules. That should easily be enough to shatter a skull at Jai Ali speeds easily. It's very likely that the Ice ball will also shatter upon impact, meaning less time for the bits to melt away. [Answer] I have read a fiction book where murder created bullet from ice covered by chocolate coating. Then he armed pistol with this bullet and killed shooting to the open mouth. The main idea was that there was no bullet left which made investigation hard. This murder was made at point-blank range and brain damaged directly. So if you want ranged weapon you need happy shot and great sniper. Since you want crossbow which is less powerful than gun, you need a good luck also. But I suppose it's possible. The idea of such kill is to put damage similar to punch, like boxer could kill with single (un)happy knock. Ice bolt even doesn't need to penetrate the skin. Crossbow is more powerful than boxing punch so all you need is to have projectile durable enough to not break while hitting (or most of energy would be wasted to shatter instead). It's possible with some cover: clay, paper or something else what would be supposed as a trash at the place of kill. Ice bolt is relatively light and would lost energy very fast. That's why I suppose such shot should be done at a close range (less than dozen meters). Also no armor on a prey and target only to the head. And lot of luck. --- The story was [The demolished man](https://en.wikipedia.org/wiki/The_Demolished_Man) by Alfred Bester. ]
[Question] [ A bit of a thought experiment I'm trying to develop further has hit a stumbling block. The basic premise goes like this. > > All of humanity one day wakes up to the entire world having been changed drastically on them. Important to this plot, all humans maintain the knowledge of the world as it had been with no obvious changes to memory. Changes, however are vast. > > > Everyone's appearance has changed in some way, some more drastic than others. An approximate 30% are even different genders than they started out as. Everyone's position has changed at least some, but most are still within the boundaries of their geographic location (see country). Rare cases may include people now halfway across the world. > > > History and all documentation appears to have been changed as well. Your new body has a new name and a new history to it. All documentation, physical media, internet and any other source you can think of has been changed to reflect this new identity. There is no proof, except in your mind, of who you had been and most of the people you had known are now scattered randomly dealing with the exact same problem. > > > Now, this makes for a really compelling start to storytelling and I really like it, but I've hit a bit of a stumbling block. The basic premise makes it almost entirely likely that the "new" leaders of countries are completely unqualified and no one would listen to them anyway. To prevent this turning into a post apocalyptic story we need to have a way to quickly return to a semi-stable government across the world. In order to accomplish that, at the very least, we would need some way for our existing leaders to prove who they are and establish themselves. Bonus points for a solution that don't allow every single person to easily return to their previous lives without much drama, but still prevent global collapse (if that's at all possible). What is the easiest/fastest way for our leaders to definitively prove themselves without any physical proof? [Answer] You can't. Anything the public could take as proof is public knowledge, so other people could try and [fake it](https://en.wikipedia.org/wiki/Sarah_Palin_email_hack). But you don't need to. People become leaders by leading. Whoever is capable of reducing panic to tolerable levels is a good leader by definition and it doesn't really matter what their job was before. This event would be world shaking. Probably significant portions of the populace would change their opinions about various things, so previous election results wouldn't be very meaningful anyway. In less democratic countries there probably won't be much interest in restoring the previous status quo exactly. [Answer] /What is the easiest/fastest way for our leaders to definitively prove themselves without any physical proof?/ Lead. What is a leader? You are thinking of elected officials, mayors and the like. But a mayor of one city is just a citizen in another country. The strongman of one nation is a tourist in another. These people wake up in different bodies and different countries. Leaders should prove what they are by leading. I can see that in a time of chaos and confusion a person might step up and lead because she sees that there is a need and because she can. I would definitely hope for such a person in my close vicinity in such circumstances. Some of these people might have been leaders in their prior lives. Some might have been leaders in their youth. Some might never have had the opportunity or interest to lead before. [Answer] Well this is an event that has happened to EVERYONE all over the world, so people wont have a hard time accepting that bodies have been swapped. They'd only have to look at themselves as proof that it actually happened. However, you said the bodies swapped, but the minds should still be the same and the knowledge within. Lets take the President for example: He/she would still know things that only the President would know - codes, secret info, etc. Family members would still have memories that only they would know. I am convinced that if my lady friend told me a handful of things in this body swapped world I would totally know who she was based on those things. No matter where in the world she ended up she would still know my phone number, she would still call me up, and though she sounded different there are things that only she would be able to tell me about our private shared past. It would take a long time to get back to normal, and there would be a lot of trust issues along the way, but everyone has some knowledge that is still unique to them and a handful of others. This body swapped world sets up some interesting stories. What if a racist mans son turned up as a black guy? What if a murderer turned up as his victims loved one? What if the richest guy in the world turned up as the poorest most bed ridden guy who lost his job because of the rich guy? Good luck with your idea! [Answer] Part of the problem you have set up is that you will have no way of knowing imposters from the "real thing" absent information like passwords, bank account numbers etc. Even that is problematic, because the security guards at the gate are not the same people, nor are the bank managers reviewing bank accounts etc. Donald J Trump, Vladimir Putin or Xi Jinping are nowhere near the seats of power, and whoever is inhabiting their bodies will not know the codes and procedures to initiate a lot of things (and the officers carrying the "footballs" would not be the proper people either). At a high level, things will start to collapse, as the elaborate hierarchies and systems of modern civilization will not have the people who know and understand them actively monitoring and controlling the systems. This will be "[Life After People](https://infogalactic.com/info/Life_After_People)" with people, and anyone near an oil refinery, nuclear power station or other high tech, high energy systems (think steel mills and the like) will suddenly be engulfed in major industrial accidents (they won't even know how to properly shut down the systems). At lower levels, people with natural leadership abilities will step forward and try to organize families and communities for survival. Your idea of politicians trying to regain recognition might even backfire, since politicians throughout the West have spent decades squandering their goodwill and trust to a very large extent, if Mayor McCheese wants to return, there is a good chance he will be told to take a hike, the new guy is doing a far better job than he ever did anyway. And of course the population of the town isn't even the same people as the ones who elected McCheese in the first place. In non democratic societies, the disappearance of dictators and their enforcement mechanisms will likely result in anarchy and the development of small "survivalist" communities, many of which may be determined never to fall under the control of their former masters (this does not preclude the development of strongman rule and "new" dictatorships arising instead). So kicking the props out from under civilization is going to result in an [Apocalypse](https://infogalactic.com/info/Apocalypse) anyway. Since the word is derived from the ancient Greek "uncovering" or "revealing", it may work out as an excellent story mechanism, since the true characters of people will be revealed under these circumstances: leaders will step forward and people can be shed of the constraints of their old identities in the new environment. [Answer] I think a little handwaving might make this nearly recoverable, and tinfoil might substitute. It might be expected that military and first responders would immediately rally to central and vital locations and impose martial law until things got sorted out. Handwave or tinfoil that there are enough who are capable enough to handle that even though they don't start with the guns and badges. If that works re-establishing our social network is non-trivial, but should be doable given enough time. Getting that time requires another handwave, or tinfoil; if there are strategic stockpiles of food water and medicine say in government or secret society bunkers now n the hands of regular Joes, or if the NSA or facebook staff are so far up our butts they know how to break into everything and get critical skilled people back to work quickly. Give time pretty much everyone has someone who knows enough about them to determine if someone is trying to impersonate them, but it might not be easy to completely sort out communities with a high proportion of incarcerated criminals or other kinds of people who would really like to trade lives with their neighbors. It should be fairly straightforward to establish a small pool of possible people who could identify important people, and then a pool who could identify them, and so on, until a broad consensus or web of trust differentiates leaders from con-men. If society is interested for whatever reason in trying, probably whoever climbed the chaos in the first act would try to find a way to hold significant parts of what they won though. [Answer] That would really depend on which part of the world you want to set your story in. Here in Israel, for instance, if everything changed around me, first thing I'd do is check whether Israel still exists at all. Then, as long as Israel is not put in immediate existential danger, I'll consider it sufficient proof of the leader's competence. In other countries, sufficient proof might be that the new leaders (unlike the old ones) don't fill their pockets at the country's expense, but instead do something, anything, for the lower-middle class. I think, with so much other problems going on in everybody's life, people wouldn't notice the politicians, unless the politicians start making a mess of things. So for leaders to prove themselves, they'd simply need not to make things worse. ]
[Question] [ There's a city. It houses just over 200,000 people. What's special about this city, is that it's the only city. About nine kilometres from the center of the city, in all directions, is a fog. Any roads that lead out of the city will inevitably somehow lead back into the city, and going off road has as much success. There is no known way to truly escape the foggy event horizon. Twice a month, a traveller with no memory will wander into the city, and any writing they have on them will be distorted and unreadable. They cannot leave through the fog, and they start with nothing magical. The city has an abundance of domesticated animals, farms, quarries, mines, clay pits, etc. It also has access to a lake, mountain, caves, forests, and various supernatural dwellings. The tech level is medieval-ish, aside from items relating to the true subject of this question. The true subject of this question is the peculiar phenomenon that occurs in the city. When a person grows a strong attachment to a material possession, it may eventually gain mystical properties. These properties will often vaguely relate to the thing they were used for, but with a twist. A much-loved book may change genre to match the reader's mood, a rope may coil automatically, a mirror may show no people whatsoever, only the inanimate objects behind them and the background, two matching rings may make nobody find the wearer attractive except the bearer of the other ring, a favoured pencil might change the scription to the way a pirate would write. These changes are usually benign, occasionally useful, and often subtle enough to go undiscovered for months, sometimes years. They will not usually make the item more durable, and usually never have effects that are quite the same as a past object. They are sometimes stolen by magical creatures, accidentally broken, and are occasionally instructed to be destroyed by their original owner in their will. There is usually about one of these per two people. More interesting, however, are items that are used communally or by an organisation. These will tend to take on more specific, elaborate, and purpose-focused effects. These include a bell that only the desired servant can hear, a waste bin that destroys any inanimate object put inside it, a pool that turns non-organic substances into copper on contact, a keg that will turn beer into a practically infinite number of different liquids, depending on how the three dials are turned (pear brandy, syrup, tar, lime perfume, blood, olive oil, nitric acid, saliva, brine, mercury, etc.) or a book that will erase crossed-out words, remember what was written on torn out pages, or even in dreams or other timelines as long as paper is placed in its position. These are rarer, and there may be one per fifty people. This likely creates a culture of holding onto things. Prices of resources that can easily be created with items will likely decrease significantly. But my question is more focused on how the economy deals with the abundant magical items themselves, not how this affects industry. [Answer] A lot depends on Item Synergy/Competition The price of the item will depend primarily on how if affects the broader economy. This will also depend on how it synergies and competes with other items. Given your examples, the copper pool will be incredibly valuable, until another item emerges that can cheaply create copper. The keg, meanwhile, will become vastly more valuable if another item emerges that creates beer cheaply. Speculation, Risk, and Corporations This will encourage high-risk speculation on the future emergence of magical items. It will also result in vast fortunes being gained and lost on a moments notice as new items emerge that nullify the value of previous ones. This could encourage a society of risk-takers, or it could encourage the formation of large corporations which pool risk and ensure that if one item loses it's value, the other items they possess will make up for the loss. Gaming the System? Another option, meanwhile, could be to game the system. Is it possible to "create" a magic item by deliberately forging an emotional bond with an object? If so, that vastly increases the competition for items, as it's much easier to get the item you want (say, a pool that makes gold). However, given your setting, this seems a bit broken. For the less valuable/more specialized items Finally, there would likely be a register of all items and their abilities, as some people might have uses for items that others do not. Perhaps a security guard could use the mirror you described to search for weapons, depending on what it does and doesn't filter? These sorts of specialty items would have value, but likely wouldn't command insane prices like the pool/keg due to the lack of a bidding war over them. [Answer] Once the novelty wears off, the items will be priced based on their usefulness. If it has a useful property it will be priced higher than one that doesn't and one that has a detrimental or annoying property will be priced lower. How much higher or lower depends on how much people are willing to pay for that feature (or save in the case of negative features). Since they aren't rare, they won't have premium pricing, just utility pricing. [Answer] Unique (or very rare) objects tend to attract collectors. Witness the effects in our world: expensive artworks, out-of-print or erroneously printed stamps, incorrectly minted coins, personalised clothing or jewellery, antique objects, and vintage cars. All of these items tend to be valued far more than mundane versions of a similar nature. Even if the objects are not terribly useful, I foresee a market developing for them. Auction houses will deal in such items, thieves will seek to steal them, forgeries will appear (a more recent not-quite-the-same object is passed off as an older one, provenences are faked, etc), museums will showcase historical items, and so on. An economy will develop around such items as it has in our world for similar rare items. Important things to consider: ## 1. Rarity Is the item really unique? Or are there multiple similar items? Truly unique items tend to be the most valuable, with the price dropping when a similar item appears. ## 2. Age Older items tend to be worth more. Antiques from hundreds of years ago are worth more than similarly produced items today, simply because they have survived the ages. ## 3. Fame The paintings of the masters are worth more than those of currently living painters, even if more recent technological advances or better talent have improved the quality of art. T-shirts worn by superstars are auctioned for thousands of dollars. Magical items created by or belonging to famous people will be valued more than those from 'ordinary' folk. ## 4. Quality An object that is inherently valuable is worth more than an object with no intrinsic worth. Therefore, a magic item created from a rare quality gemstone will be valued over something made from base metal or a straw doll. ## 5. Condition Mint condition isn't just a phrase. Items without damage on them are valued more than items in a damaged condition. Mint condition stamps, collector cards, or first edition comic books are priced higher than used ones. ## 6. Power While this can be an influence, none of the effects mentioned are overpowering. I don't see the economy being drastically altered because one tavern obtains most of its alcohol from a magical cask. After all, does the produced alcohol taste good? Will patrons get bored of the taste and seek out different ales? Will the cask get stolen? The last is most likely to happen. [Answer] These items are metaphors. What you describe is subtle and well thought out. The fog bound city is surreal and [Kafkaesque](https://www.urbandictionary.com/define.php?term=Kafkaesque). I am certain that your magic items are a metaphor for something else. I suspect you are writing [sociological science fiction](http://www.writing-world.com/sf/genres.shtml) (or his cousin sociological fantasy). > > Soft/sociological science fiction is character-driven, with emphasis > on social change, personal psychology and interactions, etc. While > technology may play a role, the emphasis is not so much on how that > technology works, but how it affects individuals or social groups. > Robert Silverberg's short story "To See the Invisible Man," for > example, focuses on how a futuristic form of punishment affects the > individual and the surrounding society. Ursula K. LeGuin is a noted > author of sociological science fiction. (For more information, see How > to Write Soft SF, by Penny Ehrenkranz.) > > > The first paragraph of your OP hints that you can write. This could be a powerful story - not dungeons and dragons stuff but real literature. Now you have a task. You may or may not be aware what you are actually writing about or you may have an idea you can coax out from the shadows and shake hands with. Wrap your head around what you mean and then assemble these magic items in your story to bring your meaning forward. I hesitate to put ideas in your head, but here is one. These items are concrete and concrete readers can appreciate them, and by making them items they step a comfortable distance from the psychology of the interpersonal. But we all have magic, now, in the real world. The association with a person, loving him or hating her, cooperating with him, hiring her - all of these interactions partake in the magic an individual has cultivated over the years. In your story you can explore that at arms length because everyday items are playing the role of the magic of an individual. How do I partake of your magic in the real world? I can eat a meal you made, or laugh at your silly jokes. I can sleep dry under a roof you fixed. I can sing a song you wrote a hundred years ago. We are abundant too. How does commerce and the economy deal with the real magic that individuals possess - and can cultivate, and can neglect, and can pass along to their students and children? Can you explore these ideas with your magic items? ]
[Question] [ I'm building a world with almost weekly extreme windstorms, driving the residents to either live underground or in the 'wind shadow' of sealed-off valleys. To sum up the windstorms' power, "You know that boulder that was next to your house? Yeah, it's out of the country now." I want to know what this would do to a landscape. What would it look like? [Answer] Several notable effects can be envisaged: ## 1. [Wind erosion](http://milford.nserl.purdue.edu/weppdocs/overview/wndersn.html) Most of the flat land will end up becoming wasteland or desert (the process of natural desertification), with the top soil being blown away and deposited elsewhere (likely ending up in the ocean). Over a long period of time, hills will be worn down, as will any mountains that are not formed from very hard rock, such as granite, and even granite might end up being reduced by the extreme weathering. ## 2. [Dust Storms](https://en.wikipedia.org/wiki/Dust_storm) Due to the suspended particles of soil in the air, dust storms will be commonplace, and severe air pollution will prevent anyone from breathing normally without some form of filtration mask. Due to this pollution, sunlight will be reduced significantly. Visibility will be poor, and it will be easy to get lost in such conditions. ## 3. Loss of Surface Vegetation and Animal Life Due to wind erosion, dust storms, and lack of sunlight, very little surface vegetation will survive. Water sources (rivers, lakes, ponds) will become clogged and tainted. Animals will perish, herbivores being unable to find food and/or drinkable water, and carnivores for lack of prey and water. Surviving plants and animals will typically be desert plantlife and creatures. So how would this occur? ## 1. Water World A water world will tend to produce superstorms due to the lack of large terrain features to stop such storms from developing to full capacity. On Earth, this can be seen is how the most destructive typhoons and hurricanes develop out in the ocean initially. A classic book that describes such a world is George R.R. Martin (yes, the guy who wrote 'Game of Thrones') and Lisa Tuttle's Windhaven. ## 2. [Impact Winter](https://en.wikipedia.org/wiki/Impact_winter) Caused by a large asteroid or comet strike on the planet, this is a mass extinction level event, generating the same amount of explosive force as thousands of nuclear bombs. With tremendous amounts of dust thrown into the atmosphere, this would lead to massive destabilisation of weather systems and up to thousands of years of extreme weather, including superstorms. While the superstorms wouldn't be continual with a single impact, you could have frequent collisions of smaller asteroids setting up a permanent change to the planet's weather systems, causing constant superstorms. ## 3. [Abrupt Climate Change](https://www.c2es.org/content/the-day-after-tomorrow-could-it-really-happen/) This occurs when a tipping point in the planet's climate is reached due to pollution or similar causes, creating an irreversible change to the weather. While planetary weather systems tend to be self-correcting, they can eventually be overcome. The best example of this is The Day After Tomorrow (2004 film), with the linked article above exploring the possibility of it occuring in real life. [Answer] As Tenryu points out a water world suits and has many advantages. It doesn't have to be all water or only a few tiny islands; as long as there aren't major obstacles that form dominant currents and no major extended mountain ranges you're good. It can be several Australias, a bunch of Englands, Madagascars, etc, as long as they don't form extensive undersea ridges or land barriers. This way no major North-South ocean currents distributing temperature or wildly dipping jet streams doing the same in the atmosphere. What you wind up with is a banded planet (think Jupiter) with most extreme winds near the equator, the occasional giant eye storms lasting however long you wish (cool to think of people/creatures moving with the eye of an enormous storm over centuries - safe inside but deadly trying to get in or out). In pockets between the bands and further toward poles the winds decrease but so does the temperature, drastically, in a direct linear manner. All the wind-bands don't need to go in the same direction either and can't if you want big eye storms that roll along at the boundaries between opposed direction bands. - super cool to have different groups moving in different storm eyes, sometimes as storms roam they'd come across the ruins (very flat or entrenched) of another group or somewhere they'd been before. Of course they'd either have to haul their boats/barges or have quickly growing materials to plant and harvest for making new ones - while maybe knowing/recongizing where they were and how large the land mass/island was so how long the storm would be over it (weeks or centuries). - all the while doomsayers saying the storm will end, the eye collapse and doom come hither. - meanwhile those living on the habitable fringes have regular, unchanging weather (like living on the Pacific NW coast where it's mostly cold, cloudy, rainy and windy day after day after day and the sun becomes semi-legendary and you only notice the rain when it's going up your pant legs. [Answer] Landscapes such as you describe are called [Aeolian landscapes](http://www.eniscuola.net/en/argomento/landscapes/landscapes-shape/aeolian-landscape/) [![Aeolian landforms](https://i.stack.imgur.com/jGms0.jpg)](https://i.stack.imgur.com/jGms0.jpg) <https://en.wikipedia.org/wiki/Aeolian_processes> This rock reminded me of the one in your OP except the wind changed and so it got turned around. Blown rocks will leave paths. [![rock with trails](https://i.stack.imgur.com/hI5u8.jpg)](https://i.stack.imgur.com/hI5u8.jpg) <https://www.nationalgeographic.org/topics/deserts/> When the wind picks up the blown grit will abrade everything. There will be stones of the bedrock or old volcanism carved into unusual forms. When the wind subsides the blown materials will settle into dunes according to their mass - the most massive particles settling down first and the lightest last. These dunes will overly the landscape. I can imagine conventional carbon-based life life under these circumstances in a few ways. 1: extremely abrasion resistant. Deep rooted plants with a shell or skin of the local materials could easily regenerate this shell or skin as new materials are blown into it during the storm. The energy of the blowing materials will be expended weathering this inorganic shell. 2: small and blowable These tiny plants blow with the wind - perhaps their aerodynamic properties allow them to quickly ascend to the top of the storm where there will be few massive impactors. Their own velocity will be that of the wind and carried particles and so they will not be abraded. I envision these as tiny lichen particles - when the wind starts they are the first off the ground and the last to land when the storm is over, so they always wind up on top. At the end of the storm there would be a fine green haze settling back into place. 3: Large and blowable. These herbivores are full of lift gas (metabolic hydrogen?) and ascend to height before any storm. Nothing else is that high and so they are blown along unperturbed. When the wind stops they settle down and get to eating. 4: Tunnelers - obviously. 5. Fast Like desert animals that complete their life cycle in the course of a week after the rain, these animals would complete a life cycle between storms. The next storm would blow away the dessicated husk of the adult and disperse the seeds - much like a tumbleweed! [Answer] This isn't so much an answer but more an example of what someone else has done. The Stormlight archive by Brandon Sanderson features the world of Roshar. And Roshar notably has a gigantic storm (called a highstorm) that is constantly circling the globe, it never dies out. It is strong enough to throw boulders just like you said and is large enough to cover the entire latitude of the worlds sole continent (by the same name, Roshar) as it moves across. The highstorm hits regularly, about weekly. This has lead to massive change in Roshar's ecosystems compared to earth. It should also be noted that unlike real world storms, highstorms deposit a substance called Crem, which later hardens into stone. Naturally because of the winds and the crem, Roshar has no loose sediments like dirt or sand. This means that all plants must have roots capable of digging into the rock. All life must also have adaptations to survive a highstorms passing. Plants have strong bark and are capable of pulling in leaves and branches for protection, e.g. grass pulling into holes in the ground. Almost all Rosharan fauna is crustacean to survive the storms with their hard shells, notable examples being the domesticated chull, a crab the size of a carriage and greatshells, crabs the size of islands (note that Roshar has a lighter gravity and denser atmosphere so yes they can survive their own size). Rosharan life is also dependent on the highstorms, the mineral rich waters are vital for life. The sole exception to this ecosystem is the country of of Shinovar, which has large mountains protecting it from highstorms so they have a more Earth-like country. Human society has also made adaptations for the highstorms. Buildings are only built in the shelter of natural formations (which there are plenty of thanks to crem) and then are still designed with the storms in mind, with slanted roofs and no windows the storm facing side. I understand that this is quite an extreme and exotic example but it is one none the less, hope it helps [Answer] Maybe the planet rotates so fast that the Coriolis Effect is strong enough for hurricanes to form over freshwater and the hurricanes merge to make bigger and bigger hurricanes until they finally die out. A storm powerful enough to blow big boulders out of the country would do so much damage that there would be a massive die-out of animals and plants. Even seeds would likely get blown away and the landscape might become a desert. This would make it hard for a civilization to get back to the point it was at unless the materials and technologies they use can deflect boulders and other much heavier objects as well as mimic sunlight and rain as much as possible. ]
[Question] [ This question is inspired by salmon swimming up waterfalls. I am aware that it is an entirely different thing, but I felt that it was worth mentioning in understanding the question. “What would need to happen (or prexist) for a person to suddenly be able to swim through the skies during a rain shower?” Environmental factors... * Density of rain? * Speed if rainfall? Biological factors... * Ability to move quickly? * Limitations requiring specialized gear? These are just some thoughts that I’ve had on a potential answer. A starting point for those who know more than me, or maybe just a red herring for all I know. Regardless, the ideal answer illustrates the combined requirements for a human person without the aid of magic or advanced technology to swim through the sky during rainfall. [Answer] The basic answer is that ... they need to apply enough downward force to the raindrops to move themselves upwards. However, because rain is small, heavy and has a high terminal velocity, moving a [fin/arm/thing] fast enough to hit the rain drops would likely mean you'd get a higher efficiency using said appendage as a wing directly. Of course, if you lower gravity, then you have slower rain and a lighter person and it becomes more possible, but you'd still end up with some appendage that is more fin or wing than human arm. Also note that salmon can't swim up waterfalls for any great lengths of time. They jump up as quickly as they can rather than swim up gradually. So I doubt you'll end up with your person casually sauntering around the sky. [Answer] If you want to swim in a medium you prefer to have buoyancy supporting you. Buoyancy is related to the difference in density between your body and the medium in which it is immersed. If you consider the air during rainfall, you can estimate the average density as the weighted ratio of the volumes of air and water. Since the average density of a human body is about 0.9 (water being 1), to have some decent support you would need to have at least 90% of water per volume of space. This equals to be in a waterfall, where you would then struggle to oppose the downward momentum of the dropping water. [Answer] If a person would be able to swim through the skies while it rains, there would have to be some very unusual conditions. Possibilities: A. Biologically, water causes the being to move upwards on contact. However, this is highly unlikely and quite complicated. B. Technologically, contact with water fuels some sort of engine. C. Sheets of rain. Normal swimming, maybe some scuba gear. This probably would mean that rain would come down differently in your world, something akin to the below, but a lot denser. ![sheets of rain](https://i.pinimg.com/736x/f7/92/e0/f792e0664e837881ac75e24aca3f5602--storm-clouds-rain-drops.jpg) [Answer] Yes, but it would probably require flippers, being a lot lighter, having more strength, and extraordinary weather conditions. The amount of upward force produced if one assumes that the pressure on the "wing", is proportional to the surface area of the "wing" that faces downward. Wearing giant flippers would definitely help because that means more contact with rain. In order to fly with these gigantic (and presumably heavy) flippers, one would need a lot of strength. This would allow the user to exert more force in total on the flippers, and would also allow him/her to "swim" faster. I suppose being a lot lighter isn't really a requirement, but would help make flying easier. After all, that weight is dragging you down. Finally, we have the weather conditions. The largest raindrops ever observed were about 8.8 millimeters across. Laboratory studies show that theoretically, the diameters of these raindrops could approach 1 centimeter (if isolated). Ignoring the isolation rule, one could, using super strength and giant flippers, probably swim around with much difficulty. In order to ease the workload on our pour user, it would be much more helpful if the rain came down in sheets like @Aethernolt said. TL;DR: Your guy can swim if he has giant flippers, a lot of strength, being light, and being in the middle of a tremendous rainstorm with giant raindrops. Troll Method: Make the guy lighter than air. Edit: Lighter gravity, which causes less downward pull and allows for the formation of larger raindrops, would also help. In fact, if the atmosphere was thick enough (with water vapor from the rainfall, for example), and the planet's gravity was sufficiently low, you wouldn't need raindrops. You could just strap on some wings and fly. (If this method works as well, see <https://what-if.xkcd.com/30/>) [Answer] Maybe not rain but how about snow? Snow falls slower because of the larger area, so you would not need to push it down as hard or fast. Maybe something like a fairy fly's wing, but giant for humans. ]
[Question] [ In the fiction, A Song of Ice and Fire/Game of Thrones, one high castle in the mountains, the Eyrie, has so-called [sky cells](http://awoiaf.westeros.org/index.php/Sky_cell). Those cells are left open to the cold sky. The Eyrie is 600 foot/180 meter above the valley below. It is astride the peak known as the Giant's Lance, a peak of 3.5miles/5.5Km. For the climate, it can change a lot, but to summerise, its temperate in summer, and colder (with a lot of snow) during the winter. As I would like to know the longest survival time, consider it's during summer, with a temperate climate. The prisoners have clothes and a thin blanket. the valley below, in a mountainous region. As it's open, the prisoners suffer from wind, and probably rain/snow (maybe depending on the sense of the wind though). It is also said that the floor slopes slightly, and the cell is miserably small. How long could someone survive in such harsh conditions? What is the most probable way of dying between hypothermia, suicide, accidental fall or madness? [Answer] # Depends on the temperature According to [this paper](https://www.ncbi.nlm.nih.gov/pubmed/8530210), survival time in -20 C temperatures (-4 F) with 5 km/h wind and two layers of loose clothing is 15.4 hours. The same wind and clothes conditions at -30 C (-22 F) is 8.6 hour. Using a [wind chill chart](https://www.ncbi.nlm.nih.gov/pubmed/8530210) we can estimate other temp combinations that would be equivalently deadly. For example, with biting 30 km/h mountain winds, the temps required for equivalent 15 and 8 hours deaths are -15 and -23 C, respectively. # Conclusion As long as the person doesn't have a coat, any temperature is below -10 C (15 F) with some decent wind will kill the person within a day. Keep in mind, this is full on hyopthermia death; frostbite enough to lose hands and feet and such will happen much sooner. [Answer] For a clothed individual it depends on rainfall and wind direction, if the cell is dry and they can get out of the main force of the wind they can probably survive quite a while. I'd say the main cause of death would be a toss up between exposure when there's rain and unfavourable winds and accidental falls/suicides in warmer drier weather. If the prisoner is naked then they cann and probably will experience irreversible, and eventually lethal, damage from exposure in as little as three hours according to the "threes of survival" which state that you can survive: three minutes without oxygen, three hours without shelter (cloths count), three days without water, and three weeks without food. [Answer] Skycells as they were written are more likely to cause someone to freeze to death. The answer to this question is largely dependant on exactly how high the Skycells are. And for this you'd need to be exact. There are at least 10 mountains on this earth above the height of 20,000 feet. It took them a long time to get up the mountain, so just going to say your estimate of a couple thousand feet seems...off. By a lot. The book mainly talks about people going mad and falling out accidently, but, it's the cold at that altitude that is more likely to kill. > > You will lose an average 3.5 degrees Fahrenheit for every 1000 feet of elevation you gain. > > > If you start out at 1000 feet, and climb to 6000 feet, that’s a 5000 > foot difference (6000 – 1000 = 5000). So, since you’re gaining 5,000 > degrees, you’ll use a 5 in your calculation. 5,000 feet, times 3.5 > degrees. Just drop the (thousand). So, ( 5 x 3.5 = 17.5 degrees). So > roughly, you’ll expect to lose at least 17.5 degrees. I always round > up to the nearest 5 just to add some safety buffer, so a 20 degree > difference. Simply subtract this number form your expected low, > according to the forecast, and you have your expected temperature. > > > Ex: The weather man says it’s going to me 60 degrees today for the > high in your city. Your city is at 6,000 foot. If you’re climbing from > 6,000 feet to 14,000 feet, That’s an 8,000 foot difference. 8 times > 3.5 is 28 (8 x 3.5 = 28). You can assume a 30 degree difference after rounding, so it’s only going to be 30 degrees max at the top of the > mountain (A high of 60 minus your 30 difference)! Remember, that’s for > the high. Always consider your low temperatures too. > > > Besides the base height, there's also wind chill to consider. Questions to ask: * Exactly how high? * What's the base temperature at the bottom of the mountain? * Wind Chill? * Exact pitch of the floor? * How icy are the conditions? It doesn't need to be as high as in the books to kill folk--could be as little as 400 feet, as long as the ground beneath is rocky and jagged. Do that, and pitch the floor a little more, and it's more likely that they would die from something other than hypothermia. But seriously, it's hypothermia. [Answer] At high altitude, minimal protection and especially in cold weather. Mostly likely death is exposure a.k.a. hypothermia, which could be within a matter of hours. Time to death for a swimmer in open water in the North Sea is around 30mins. A fully equipped mountaineer in a storm can survive several hours before frostbite begins to set in, death will not be far behind. Dry cold is relatively survivable given suitable equipment, however suitable equipment is not given and the environment is most likely to be at least damp, if not outright soaking. Survival times are likely to be measured in hours though a few days is possible if conditions are particularly favourable. [Answer] "How long could someone survive in such harsh conditions?" As long as author would like. Sky cells are usually used to show a great feat in character. Either by surviving for a long time (until rescue came) or by escaping such prison. In game Far Cry 4, character escape such cell by using "magic" (and drugs, and demons). In Thorgal comics book in issue "Between Earth and Sun" three people are placed in "mouth of the sun" to die from sun that shine directly onto them. They wait for the rescue. If a person is put in such cell to die then why not just kill them on the spot? Would save hassle of going to such cell and leave prisoner there. If a person is put there to suffer hard conditions it would be better to put her to work in mines or something. If a person is put there to restrain them for a certain time then the conditions should allow him to survive. And experience regular prison life in isolation but with a very large window. ]
[Question] [ What sort of biological challenges and modifications would it take to create a snake with a head on both ends? Assume that said snake is created by a deity and thus some complicated evolution path is not required. It does however require that this species of snake be able to survive and sustain itself within a stable ecosystem. I’m not looking to discuss the complexities of evolution nor the whole of an ecosystem, instead I’m looking specifically at biology here. Two challenges that immediately come to mind are the digestive system and the reproductive system. If you see additional challenges, please say so. The answer that I’m looking for addresses the biological concerns and offers a solution. [Answer] Head musings: what is a head? Can it still be a head if it does only some of the things the first head does? First, a mental exercise. Consider the penis. One organ and one orifice combines urination and procreation, and some think also sexual display functions. Certainly these functions could be split or others added: female mammals have 2 orifices for these functions, and the reptiles include defecation in the single orifice of the cloaca. The head of a vertebrate also has multiple roles. It contains the start of the digestive tract. It contains the start of the respiratory tract. It contains mechanisms for making sound. It contains weaponry. It houses the brain and sensory apparatus. And: by its appearance and appurtenances, it proclaims to friend and foe: I am the head of the animal I am. It really is a ridiculous amount of stuff to house in one place and I am sure the echinoderms think we are silly. The question: a snake with two heads. If we can have a thing be a head but not necessarily carry out all of the functions of our own human head, it becomes much easier. Easiest is the single function: to declare to the world "I am a head". Here is the amphisbaena, a real reptile named after the mythical two headed snake. Also: the fat-tailled gecko. <https://www.flickr.com/photos/nclarkii/5621212197> [![amphisbaena](https://i.stack.imgur.com/JnDFE.jpg)](https://i.stack.imgur.com/JnDFE.jpg) [![fattailled gecko](https://i.stack.imgur.com/jb4hn.jpg)](https://i.stack.imgur.com/jb4hn.jpg) The tail of these reptiles appears like the head, and vice versa. If the simplest head is a thing that proclaims "I am a head!" then these things have 2 heads. --- What about a more functional head? Could a second head take on more of the duties performed by the first? The easiest would be offensive / defensive duties. Duplicating a mouth that can bite would be doable. Defensive apparati on the "tail" is already a done thing, with the simplest being big iguana-like tails that lash and the best probably being the scorpion. It is a good place to put a tail gunner head, because probably you are running away. I like a division of labor between the heads. Main head is in charge of eating and tail head is in charge of defense. Eyes on the tail head would help with that. And it occurs to me that a second defensive snake head that could bite might benefit from a venom different from that of the first. A head that eats needs venom with the ability to quickly incapacitate prey animals. A head running defense needs venom that hurts terribly (like bee venom), blinds, or otherwise deters predators probably larger than the snake. What about excretion? Digestive tracts are linear and you don't really need two. The cloaca could be under the chin of the tail head. Or the tail head might use the proximity of waste materials to augment its defensive apparatus. [Snakes already shoot pee and poo defensively.](https://io9.gizmodo.com/on-top-of-everything-else-snakes-can-spray-stink-on-yo-1580541532). Using that good stuff as a carrier for sprayed venom seems awesome for a defense tail head. I am thinking of a medieval Game of Thrones type world, where one of the Kings sidemen is called Tailhead (not to his face) because his role for the king is similar to that of the above described tailhead of the 2-headed snake. --- Last: breathing. On thinking about this 2 headed snake I wondered: how do snakes not compress their trachea shut when swallowing huge prey whole. On reading up, exactly that happens. Snakes have an adaptation for holding their breath for a long time. <https://sites.google.com/a/jeffcoschools.us/snake-respiratory-system/human-and-snake-respiratory-system> > > Another lung difference is that snakes have 2 separate lung chambers > in the right lung. The first is the same as a humans, but the second > is an air sac. The second is for storing oxygen, because when snakes > eat their food it fills up their mouth not allowing them to breathe. > The additional air allows them to survive without breathing for up to > two whole hours!! > > > If you could breathe out of a head different from the one with its mouth crammed full that would be a sweet workaround. [Answer] The psychological effects. (of a snake? yes:) Where will the snake go? Where head 1 wants to go or where head 2 wants to go? For a snakes movement, the alignment of the scales is important. So if it's exactly split in half, I assume half of the scales would have an alignment for head1 and half for head2. How will they cooperate? They can probably only crawl around in a U shape, which is interesting when navigating obstacles (like a tree). So perhaps, the 2 heads always have to stay very close together, so they form more of a loop than a U shape to reduce the chance of getting entangled. Hunting: When hunting, snakes rely on sudden very fast movements. Basically, they turn their body into a loaded spring. With 2 heads: is one head the "base" of the spring? How do they decide which one? If they both jump, ..... If it's long enough, they could try to attack their prey from 2 sides at once, thus gaining it some advantage. So now, it doesn't act like a spring shooting out, but more like a classic trap with 2 spring loaded 'danger heads' shooting towards one another. If they miss though, what happens if they bite into each other? You already mentioned the digestive tract, but did you also think of the psychological effects of this topic? (Which head gets to eat (first)? Does it make a difference to them? Do they rip their prey in half?) Four eyes see more than two, so that's another advantage. What happens if one head dies? What happens if you cut it in half right in the middle, what if you cut off one head right at it's base? What if there is a dominant "eater", but it loses it's teeth, can the other one jump in? Do the two heads communicate? Internally (nervous system (=might appear as a sort of telepathy)) or externally (sounds,...)? [Answer] This two-headed snake could be a pair of amphisbaenians which, in place of tails, share a brain-case which houses the brain, with the brain-cases of the skull only containing the end of the spinal cord. They could be made more snake-like by giving them snake-like heads and markings ]
[Question] [ I previously asked [What measures might an ancient civilization take to protect itself from extreme heat?](https://worldbuilding.stackexchange.com/questions/95968/what-measures-might-an-ancient-civilization-take-to-protect-itself-from-extreme) The answers gave some useful suggestions as to how cities could be adapted. For convenience in the next question I will call these people the “Androy”. The principle Androy city is now suitably adapted to the heat, but uses a lot of water. The aquifer they rely on is becoming depleted and on average each year the Androy need to delve an additional meter to ensure that their supply of water is maintained. Assuming the aquifer is as deep as necessary, what methods could the Androy use to maximise the water extraction process, roughly how deep can they get and what ultimately prevents the Androy from obtaining enough water? Assume a surface layer of sand and mud with a water bearing sublayer of limestone 5 - 10 meters below. The city population is at least 50,000 but may be adjusted if it helps The Androy can use any technology that was available to any ancient society in our world prior to 400 CE Note this is the second in a series of four related questions Edit A hand dug well 1285 feet deep seems possible! <http://www.mybrightonandhove.org.uk/page_id__6948.aspx> Point od interest from my researching [Answer] My grandfather dug a well by hand on his ranch in central Washington. 6 foot square, 160 feet (50 meters) deep. The digging was fairly easy, as it was the Ringgold formation (wind deposited fine sand and clay from a few ice ages ago. Similar wells have been dug in the Middle East. However he didn't pump by hand. He build a float at the bottom, and put in an electric pump. Let's extend this to 100m. To lift a kg of water up 100m you are going to expend about 1000J A person can do useful work at about 100 W for long periods of time if well fed. <https://en.wikipedia.org/wiki/Human_power> (claims 75 w, but with training it will improve) A watt is a joule per second. So a person using a perfect device could bring 6 kg -- 6 liters or roughly 1.5 gallons of water to the surface per minute. You would likely do this either with a chain of buckets on a rope so that the weight of the bucket coming up is balanced by the weight going down. This would be powered by a walking cage to use the big muscles in your legs. If you can get the friction down to 50% of the energy one person brings up about 200 liters -- about 1 barrel -- of water per hour. If you have 12 hour shifts (slave labour) each slave brings up 600 gallons a day. In a hot dry climate a person can sweat out about 4 gallons of water a day. You will need some additional water for cooking, washing. Call it 10 gallons a day. So at this level you need 1 slave on the water wheels for each 60 people total. Crops. You can do dryland wheat farming on 10 inches of rain a year, if you fallow the land alternate years. Takes 16 inches for annual cropping. In a desert climate it will take more. Tomatoes take 60 inches of irrigation per season in the San Joaquin valley. Barley can do 100 bushels/acre, or about 3 tons. (60 lbs/bushel for most grains) Romans marched on 2 lbs of grain a day. 700 pounds of grain per person per year. An acre then supports 4 people and a few mice. An acre is forty odd thousand square feet. So a foot of water is 40,000 cubic feet of water or about 300,000 gallons. So it takes 500 man days to pump the water. You are not irrigating with human muscle power. At 1/100 the depth (1 meter deep) your workforce is larger than the productivity. Ok. Don't flood irrigate. The Israelis are good at using small amounts of water for crops, putting it exactly where it's needed. Or have it rain some. Soon as you get rain on a reasonable schedule, you have vegetation that isn't farmland. You can graze critters. This is also how the Sahara, much of the middle east, and Greece became barren -- over grazing. This in turn modifies the climate. If plants aren't transpiring into the air, there is less water to make rain. Animals don't help much. Straw doesn't have enough nutrition to keep a cow going by itself (has calories but little protein) , so you need some of your grain too for the oxen. So you need a different crop. But you need also to justify some combination of lower water use or higher productivity. (Potatoes AFAIK are the highest calories per acre.) There is a reason that desert peoples are often nomadic. The exceptions occur when there is a major river in the area. The Nile flooded every spring, soaking the land and allowing long term agriculture. The Tigris-Euprhates rivers also had a flood season, and I think that they ran irrigation canals for miles. One of the reasons to build dams is to get water in a position where you can run it downhill to a field. Aqueducts from the mountains... [Answer] Lets take a look at [Roman mine drainage systems](https://www.youtube.com/watch?v=q58BWA-fdLA). They used a wheel that had boxes with holes fastened to it. First water would get in the box when it was down, then box would rise and hole would be above water. Then, at the top, box would turn upside down and water would get out through the hole. [![enter image description here](https://i.stack.imgur.com/lTklt.gif)](https://i.stack.imgur.com/lTklt.gif) At Rio Tinto mines they had a series of eight pairs of wheels like this. [![enter image description here](https://i.stack.imgur.com/kzWH5.jpg)](https://i.stack.imgur.com/kzWH5.jpg) So 16 men elevated 3 liter of water per second from 30 meter depth. In Dakia a remnants of system like this were found. It elevated water from 75 meters! Imagine a hell those men went through, rotating those wheels for years undeground... [Answer] Your folks are by the ocean, if I recall. Their freshwater may only go down so far. Inland you can go deeper, but a problem with subterranean freshwater near the ocean is that it often exists as a lens atop saltwater or brackish water. from <https://pubs.usgs.gov/circ/2003/circ1262/http://earthsci.org/education/teacher/basicgeol/groundwa/groundwa.html> [![freshwater lens atop saltwater](https://i.stack.imgur.com/1RAd1.jpg)](https://i.stack.imgur.com/1RAd1.jpg) This is the [Ghyben-Herzberg model](http://www.emwis-mt.org/documentation/context/physical%20factors_files/ghyben-herzberg.htm) explaining freshwater sources atop saltwater. I was interested to see that their studies were done on the island of Malta. If you drill too far you get down into the brackish water. Conversely if you drain fresh beyond its recharge rate (from rain etc), the pressure of the fresh atop the salt decreases and [saltwater can intrude](https://en.wikipedia.org/wiki/Saltwater_intrusion) on your wells. [Answer] A similar problem has already been solved. Suitable solutions are either * [Noria](https://en.wikipedia.org/wiki/Noria) > > a machine activated by water power and used for lifting water into a small aqueduct, either for the purpose of irrigation or for the use in towns and villages. > [![Noria](https://i.stack.imgur.com/RrRrP.gif)](https://i.stack.imgur.com/RrRrP.gif) > > > * [Archimedes'screw](https://en.wikipedia.org/wiki/Archimedes%27_screw) > > a machine historically used for transferring water from a low-lying body of water into irrigation ditches. Water is pumped by turning a screw-shaped surface inside a pipe. > [![archimedes'screw](https://i.stack.imgur.com/OI0nL.jpg)](https://i.stack.imgur.com/OI0nL.jpg) > > > You can adapt them by having animals powering the motion. ]
[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/95862/edit). Closed 6 years ago. [Improve this question](/posts/95862/edit) How do the properties of density, sharpness, brittleness of a material impact on the usability and the design of weapons. Would it cause weapons to be designed vastly different or would it make normal weapons more effective? The density of steel "ranges between 7,750 and 8,050 kg/m³". For diamond it is just 3,500 to 3,530 kg/m³. (just as an example for vastly different densities) If we were to create a regular long-sword or katana out of a material about half the weight as steel, but with similar properties regarding sharpness and brittleness, would it be as useful? What if the weight was even lower than that? It would have a weaker impact for sure, but it could be swung faster, too. Now what if we improve the sharpness? If a blade was significantly lighter, but also sharper, it would be a lot easier to use against "soft" targets. But the light weight would probably make it useless against "hard" targets if it can't cut through the hard layers. What kind of new designs of weapons (all kinds of weapons) and armor would be possible and useful if such a material existed? [Answer] If you ever cut your finger with a sheet of paper, you will have no problem in agreeing that paper is pretty sharp. Still nobody has ever started a war with an army equipped with A4 sheets... If you are going for cutting weapons (for things like an hammer or a mace you won't rely on sharpness at all) you will need mass to support the hit by transferring momentum. But you will need also less mass to make the movement of the sword not too cumbersome. In short, you need a tradeoff between ability to deal the desired amount of damage and ability of waving the weapon around. Mind that there is no unique solution to this problem: two hands sword sacrificed mobility for momentum, while katana were relying more on the cutting and agility than on the momentum. You'll guess that it depends on who is your enemy: by the time a warrior with a two handed sword has lifted it, a samurai would have already chopped his arms away. But to stop the inertia of a charging enemy a katana would do almost nothing with respect to a two handed sword. [Answer] Weapons and armour are a constant game of one-upmanship, but they are closely related. Each must be suitable for the situation and the opponent you're facing. * European weapons, such as the broadsword, were designed for dealing with relatively heavily armoured opponents. * Japanese weapons, such as the katana, were designed for relatively lightly armoured opponents. In the case of the katana, speed and cutting edge were primary. If you could create a lighter, tougher blade which held a very good cutting edge then that may be advantageous to the wielder. In contrast, one of the defining characteristics of a long sword is its weight. To make it considerably lighter, even while maintaining all other characteristics may make it an unsuitable weapon for the situation. Once firearms made heavy armour obsolete then lighter, faster edged weapons returned to the European theatre. There may be a place for your weapon with late cavalry units. [Answer] I have seen off and on the prospect of carbon fiber swords. Carbon fiber tennis rackets are amazing. I figured a carbon fiber sword would be super light and maneuverable. This guy with his carbon fiber lightsaber did not seem too intimidating until this part of the video. <https://youtu.be/NjnLrMkk-Tw?t=153> [![carbon fiber blade and some badass moves](https://i.stack.imgur.com/jxXWE.jpg)](https://i.stack.imgur.com/jxXWE.jpg) Earlier in the video he whacks that carbon fiber blade vigorously on the ground, which I think would have shattered a tennis racquet - clearly there is more than one type of carbon fiber. Carbon fiber knives (100%; no metal blade) are widely available. It did not seem to me that carbon fiber would keep an edge and I was right. Here is a piece of text from a merchant site: <http://hiconsumption.com/2016/04/best-carbon-fiber-edc-knives/>. > > Knives can even be made wholly out of carbon fiber, which allows for > blades that can be easily honed with a piece of sandpaper. They won’t > retain an edge for long, but for quick stabbing work or a few single > slashes, such dark daggers are ideal. > > > Not keeping an edge is a deal killer for a chef knife but not a sword. I am certain that people who relied on the sharpness of their swords were not using them like machetes. They sharpened them and then sheathed them. After they used them, they cleaned them and sharpened them again before putting them away. The swords came out if there was someone to kill. If rapid blunting were a big problem, one could attach a thin edge of carbon steel - maybe even in small (replaceable) sections like a utility knife, to still allow flex of the sword. A quick perusal of youtube finds plenty of videos showing how sharp these carbon fiber knives are. Sharp. As previously noted the use of this light sword would not be a club with an edge to batter people down. It would be a thrusting, slashing weapon. [Answer] There are a number of competing factors at work here. Ultimately it is a matter of how much force can be applied in how small an area. Being more massive increases the amount of kinetic energy that can be delivered in to the target, but at the expense of making the weapon more unwieldy. Making the weapon sharper reduces the area over which the force is applied increasing the pressure at the point of contact, but at the expense of making the edge vulnerable to damage. Steel is actually a very good material for making swords with especialy some tool steel as it can be heat treated and tempered. You can make a more durable sword out of titanium but it will be considerably softer than steel and you cannot temper it. Making a lighter sword would theoretically allow it to be moved faster, but I doubt the increase in speed would make up for the decrease in weight, although it would depend on the detailed circumstances in which you were using it. One key property is the sharpness and the durability of that sharpness. A material that could be sharpened to a few atoms thick at the blade edge would be a fearsome weapon if that sharpness could be maintained – which with current technology it could not. I am sure that there’s a lot of scope for increasing sword performance using modern composite materials in conjunction with more traditional materials as well as specialist high performance coatings, however unfortunately for swords, modern firearms have pushed sword development technology into the doldrums. [Answer] If you wanted to go into the realm of science fiction, you wouldn't go past [Monomolecular wire](https://en.wikipedia.org/wiki/Monomolecular_wire). It's a strand of a virtually unbreakable filament only a few atoms thick that can be used in a sword or a whip. Since it's so thin, it's like a cheese slicer on steroids. It can cut through almost anything with little effort. ]
[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/89731/edit). Closed 6 years ago. [Improve this question](/posts/89731/edit) Why do in the majority of fantasy worlds magicians need a tower, or do they already have it? Why do this type of structure? What is so magical in the tower? [Answer] Tower is a building that is easy to protect. So small feudal, ones that didn't have enough resources for a castle, often build for himself just a tower. [![Gleninagh Castle Ireland](https://i.stack.imgur.com/33jba.jpg)](https://i.stack.imgur.com/33jba.jpg) Magicians a often pictured alike to small feudal lords - sovereign, resolving conflicts with violence, having little people resources. So residence that is easy to protect is desirable. Depending on magic mechanics you can add some other explanations - for example, high tower is better for collecting mana. [Answer] The tower represents the phallus. [![Eiffel Tower, representing phallus](https://i.stack.imgur.com/bMejW.jpg)](https://i.stack.imgur.com/bMejW.jpg) from <https://en.wikipedia.org/wiki/Phallic_architecture> > > In art ahttps://en.wikipedia.org/wiki/Phallic\_architecturend > architecture, acutely vertical buildings are often seen as a symbol of > masculinity and horizontal buildings are seen as more > feminine.[25][26] The terms "phallic verticality", "phallic > erectility" and "phallic brutality" have been referred to by > architectural theorists, including the likes of French sociologist > Henri Lefebvre, who argued that buildings of phallic architectural > type metaphorically symbolize "force, male fertility, masculine > violence".[25][27] Phallic erectility "bestows a special status on the > perpendicular, proclaiming phallocracy as the orientation of space" > while phallic brutality "does not remain abstract, for it is the > brutality of political power."[2 > > > Your mages are digging that force, fertility and masculine violence! And, they may perhaps feel a little inadequate as regards the realm of the biological, and construct these towers by way of compensation. Also they wiggle wands a lot. [Answer] In fantasy, wizards are often the most scholarly of character types and therefore hold themselves above the untrained masses. Ivory tower academics are practically a trope unto themselves, as is the tendency for such elitist characters to make decisions without regard for the long term consequences to the general public. The smug superiority of the wizard, when mixed with his disregard for the welfare of others makes for an easily hate-able antagonist. The tower is the physical representation of those attitudes and attributes of the wizard archetype. Also, as a demonstration of magical ability, mastery and strength, the creation of a tall, delicate and structurally refined structure serves testament to the wizard himself, where a brutish bulwark of huge castle stones only proves the strength of his slaves. Finally, there is something to be said for the isolation and view available at the top of a majestic tower. It is easy to imagine that powerful magical energies are sensitive to interference from worldly forces. When manipulating non-earth-based magic, the wizard may need to be as far from the earth as possible. Similarly, when manipulating earth-based magic, the wizard may want to see as much of the earth as possible. The taller the tower, the better it fills both of those needs. [Answer] Henry mentioned rising above the masses. Let me add: * Churches had towers for practical reasons. Towers lofted the bells to high altitude, they served as a lookout post in troubled times, and they visibly reached towards the sky. * Trying to build a high, thin tower resonates with the [Tower of Babel](https://en.wikipedia.org/wiki/Tower_of_Babel). Hubris and all that. * We all know evil warlocks in their tower are just waiting for a barbarian hero to set things right. A tower minimizes the problems of the warlock getting away; there is one spiral staircase defended by the minions of the sorcerer. ]
[Question] [ I'm designing an intelligent alien species in which child rearing is a very labor instensive and lengthy process (their progeny take a little more than a decade and a half to mature), so much so that: * both sexes are equally involved in it * parents do not reproduce again until their child has reached adulthood These traits are natural and instinctual, they are not cultural affectations. They are in fact so ingrained that some biological processes of these beings are affected dramatically by whether an individual is parenting young or not. The changes are namely: * Sex drive is diminished and reproductive systems are made completely nonfunctional while an individual is raising a child, it is impossible for them to successfully mate until the latter has properly developped * The antlers possessed only by the males of this species (this is a good place to mention these aliens are the same ones discussed in [this question](https://worldbuilding.stackexchange.com/questions/85869/could-the-males-of-a-primarily-monogamous-alien-species-have-antlers)) shed when they are in the process of fathering kids and quickly regrow when they are not --- Now the question is, since these changes are completely instinctual/involuntary, what possible means could the creature's body use to differentiate between the states of being with and without young? What about when a child dies prematurely, how can the body detect this and react appropriately? --- Additional information: This isn't meant to be some form of magic or telepathy, for example, if you lock a male in a room after he has impregnatated a female without him being aware of such, then his body will obviously have no way of "knowing" and so it will not change to reflect the fact. The changes aren't instantaneous, it's not a simple chemical switch and they can take many months to accomplish. It should be pointed out that children don't simply have this effect on everyone who spends time with them. Only biological parents. [Answer] [Pheromones](https://en.wikipedia.org/wiki/Pheromone). Simply put, the child gives off the Pheromones. Spending time near the child, such as via raising, would cause the parents to undergo these sorts of changes. Once the child matures, they no longer give off the Pheromones so the parents can go back to mating. This does have some weird implications, like housing and the like. A mature child still living with parents would be affected by the pheromones, too, perhaps leading children to leave quickly. It would also be possible to "Skip" the raising by having a nanny or other surrogate take the place of one or more of the parents, just like the practice of a royal wet nurse. This could lead to the skipping parent(s) being able to mate more often (As long as they have sufficient surrogates). At the same time, the surrogates wouldn't be able to mate at all, as once they're done with one kid, they've got another one dropped on them. [Answer] The easiest is to copy actual human physiology. Human females normally (it's not a hard rule, but it "generally" works this way) don't undergo menstrual cycle (i.e.: no ovulation) while breast feeding. Other species exhibit the same behaviors (e.g.: cats). Make fathers also breast-feed (possibly a different kind of "milk") and the child to require both of them to reach maturity and you have all triggers you need. [Answer] While I think the 'Pheromones' answer is a really good one, it basically assumes that you're aliens have an (almost) human biology - which is not a bad thing in itself, but you can also choose differently. I have two other idea's that might work for you (but don't necessarily match all of your 'additional info') * [Seasonal breeding](https://en.wikipedia.org/wiki/Seasonal_breeder) This is actually very common on earth and humans are one of the exceptions and not the norm. If your aliens are only able to mate during a specific season (and one 'year' lasts about as long as raising a child) then obviously the parents can not get another child, as long as they have one (but also non-parents can't get children in that time). Many species on earth do this, because it's actually a lot less complicated if all children are born at similar times. * Alien breeding On earth a male usually gives is sperm (or pollen, ...) to a female and then a child grows, so the male never knows if he was actually successful and can (and often will) seek out more females. Your aliens can work differently: a more complicated and longer mating process could start hormonal reactions in both parents, that signal the growth of a child and disable fertility for next X months in both parents. You can go with all sorts of details here: from joining together in a cocoon for a few months to mating regularly over a long period to sustain or channel the birth of a child (i.e. an embryo is not formed by one interaction of male and female, but multiple ones) ]
[Question] [ I write centaurs as wild barbarians that love fighting - especially with weakling, little humans. So let's say our centaur and hero are fighting in an open, little, dirt circle in the middle of the a village. Neither of them have weapons or armor or magic spells - all they have is their fists and hooves. They several paces away. And let's assume the human half of the centaur is as strong as a football player (because I don't know how strong a centaur would actually be). How would our hero be able to win the fight? What would he have to do? [Answer] It won't be pretty because there is a very big difference in strength. But, because the centaur is so big, the hero might try to get him tired. I assume the hero is a skilled fighter, like [Floyd Mayweather](https://en.wikipedia.org/wiki/Floyd_Mayweather_Jr.). The hero must avoid contact. If he gets hit by the hooves or even by the strong arms of the centaur he will get seriously injured. He has to run (jump, roll) around the dirt circle, so that the centaur, who should try to jump on him, misses him. He always needs to change direction, because the centaur is too big to do so as quickly. As a rule, the hero should always stay on the centaur's flank. The fight should be with the hero staying on the flank and the centaur trying to rotate so that his legs have a clear shot. If I were the centaur, I'd just wait on the edge for the hero do approach me. My front legs should be fast enough to catch him. The hero cannot play my game without losing, so he would need to taunt me, call me names and disparage my centaurhood. That would cause me to try to trample him, at which point his tactics might work. If the hero gets underneath unscathed, he should try to go for the genitals, which is the only weak point. Once he does that he should be wary of the centaur crushing him. He can further upset the centaur by punching his flank, but I doubt that would be a good idea given the difference in strength. After hours of running around, the hero might try his hand with the upper half of the centaur. But, however, tired the centaur is, his upper half would still be aching for a fight. Given the strength difference, he might just try to break the hero in half. With the centaur's hands circling the hero, the hero might go for eye gouging or hitting the ears with both hands. In any case, this has a low probability of winning. Another way is to jump on the horseback once the centaur is tired enough and attempt a rear naked choke. But, if the difference in strength is too big, there is little chance it would succeed. Yet one more way is to take advantage of the fact that the centaur might get tired easier than a horse because instead of a normal head, he has a human head, hence less oxygen. Rear naked chokes or even karate chops to the neck, seem like a good idea from this point of view. [Answer] All your hero has to do is to tire out the Centaur. Seeing as how humans have a very effective temperature regulation in the form of sweating in order to facilitate our terminator-like hunting style (In which we essentially run down prey until they die of exhaustion), the hero could essentially out endure the Centaur and then, when the Centaur is exhausted, make his move by attacking the legs. Horse legs are actually very fragile compared to the rest of their body, as they are much lighter in order to run more effectively. All it really takes to permanently damage its legs is a single misstep. This means if the hero is somehow able to fracture the Centaur's legs or facilitate it (foul play is always an option), the Centaur will be unable to continue running around without further injuring itself. Even medical attention to that Centaur may never truly heal the leg, resulting in chronic pain as it does for many horses. This means that now the Centaur is tired, and cannot run without dealing damage to itself. I assume the Centaur would still try to run down the hero, which would result in terrible damage to its own leg, maybe even breaking the bone and damaging muscles, effectively bringing itself down. The hero is then free to dish out damage to the vulnerable, concussion-prone head of the tired Centaur into a bloody pulp. > > Source on Horse leg strength: <https://www.thespruce.com/horses-with-a-broken-leg-1886850> > > > Sources on the effects of punches on Human Heads: > <https://mic.com/articles/117340/this-is-what-happens-to-your-brain-when-you-get-punched-in-the-head#.cMVQeLWC9> > > > <https://www.scientificamerican.com/article/brain-trauma-what-happens-brain-hits-skull/> > > > <http://bjsm.bmj.com/content/39/10/710.full> > > > [Answer] The centaur is faster so he'll quickly close in. Also with his hooves he has the better weapon and probably the better reach. Unless your hero has superspeed or something he can only win in a fair fight with a lot of luck. Therefore let's fight unfair. Your hero picks up some dirt and throws it into the eyes of the centaur. I admit that it's difficult to hit, but let's assume your hero gets lucky. The centaur will momentarily be blinded. The hero can try to break a leg by kicking. (Others have already mentioned that the legs are vulnerable.) Since the centaur will kick blindly in every direction that will be difficult. Therefore I suggest picking up a stone and throw it. Try to hit the head. It's possible to kill somebody that way, even if it is difficult. But let's face it: When fighting a centaur without weapons you can't expect any easy solution. [Answer] Centaurs would not want to get into a close-quarters battle in the first place. Assuming the equine portion has a similar physiology to a horse, they've got a long, vulnerable flank that can't be protected either by the arms or by kicking the legs. The human merely has to force the centaur to keep spinning to avoid getting flanked, and given the aforementioned problems horses have going laterally, that increases the odds of stumbling. [Answer] # Element of Suprise & Strangulation I've hopped on many a horse that was not broken, without any trouble. Talk nicely, and hop on - if there were a human attached, I imagine I could strangle them easily, though I'm not a violent person. On horseback, you do have the advantage of being from behind with no recourse for them. Able-bodied humans have extremely solid grip with our legs on horseback. While I don't know to strangle a human, I imagine you just have to use your hands. You're behind them and they can never turn around in a way they can face you. They will suffocate. They cannot even reach you, even if they're 'bucking,' etc. There is the possibility they would roll and cause a bit of pain, but if you continue your grip on the neck, the exertion will make it more difficult for them to function these tasks. I am nothing special, but I have been on a very angry stallion for over 90 seconds while I was breaking him. I suspect your story hero (or villain) could stay on longer since she can strangle the human part of the centaur. Summary: She/He jumps on the centaur, grips with the legs on both flanks, solidly, and grabs the neck of the human part, and squeezes. Even if it falls over, just hold on - you can get your protagonist through this. Happy writing! [Answer] Luck Unless the centaur is particularly incompetent, the human's best chance is probably for a lucky break to occur which aids him. First, note that this question is constrained in such a way that it gets rid of what would be the humans best advantages in other situations. This assumes a dirt circle flat terrain, while humans are remarkably good at handling more varied and rough terrain. This also assumes no weapons where humans are very much tool using creatures. Of course, the Centaur presumably is as well, but the lack of tools will hurt the human more here. We are also assuming a one-on-one fight were humans are pack animals. Of course, so are horses and presumably centaurs, but with the size differences this hurts the human more. The one constraint that does favor the human is that we are assuming a "little" dirt circle which will constrain the centaur's ability to charge, but unless we are talking truly small area that is not a huge advantage. Others have suggested tiring out the centaur. Tiring our your opponent is often a good idea in a fight, but a centaur is not likely to be particularly susceptible to that, no more so than the human is. Humans are endurance predators, but horses were not particularly high on our list of prey and horses are also built for endurance. Unlike many other animals, they sweat much like humans do and have good lung capacity. In human vs. horse marathons, the horses (with riders) win more often than the humans. <https://en.wikipedia.org/wiki/Man_versus_Horse_Marathon> (We could of course argue that the centaur has less endurance than a horse due to being restricted to a much smaller human-sized nose rather than a horse sized nose, but I assume if we are positing the existence of centaurs at all that we are hand-waving that away. If we aren't, then tiring the centaur out is probably not only going to be plausible but incredibly easy to the point of the human winning by making the centaur exert itself slightly and then falling over under the many anatomical issues a centaur would have...) It might also appear that the humans greater agility is an advantage. And it is, but not a big one under these constraints. It would be a bigger advantage in a more varied environment like an urban area or dense forest. If you ever watch barrel racing competitions, horses can be quite nimble. Getting on its back is also a good idea, but much harder than it sounds. Its already hard to mount a horse that does not want to be mounted. (Without benefit of either mounting blocks or stirrups, it can be a pain to mount a horse that isn't fighting...) This scenario removes many of the common strategies for achieving it by assuming flat terrain and giving the human neither teamwork nor tools. And then, depending on the particular interpretation, the centaur can probably reach much or even all of its back to swat the human off. If you are writing a story and want the human to win under these conditions, your most plausible scenarios are either the centaur is not a competent fighter and makes a mistake the human can exploit or the human gets a straight lucky break such as the centaur tripping. Strategy Of course your human will have various strategies it can try to use, such as going for the legs, staying on the flank (sides) but the match is heavily stacked in the Centaur's favor. Cavalry was immensely effective on the battlefield up until motorized vehicles for a reason. Of course, cavalry was often defeated but that tended to involve weapons, teamwork, and constricted or unfavorable terrain, all of which have been essentially assumed away in this question. [Answer] The most obvious way is to cheat. You'd start with a handful of dirt to the face and kick to the joint of the front legs while he tried to clear his eyes. The front legs of a horse are actually quite delicate. No reason why a centaur would be any different. ]

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