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Training in asking Socratic questions.

How can I practice the skill of asking Socratic questions? How do I keep myself from bullshitting as I practice? I get the feeling that working with other people in the flesh is 100% required for both of these, and that the Internet is a waste of time for anything (curses!), is this true?

If you are referring to the Socratic Method as it is practiced in the dialogues of Plato, then reading those dialogues (especially the early, so-called “Socratic” ones) is likely the best place to start. You might train yourself in the Socratic Method the same way the youths around Socrates did, by observing it in action. You may also find Gregory Vlastos’ work on the subject helpful. That said, the method generally works like this: an interlocutor makes a claim, then “Socrates” proceeds to elicit the interlocutor's agreement to premises that imply a conclusion that is inconsistent with that initial claim- either because the conclusion is the contradictory of the interlocutor’s initial claim, or because the conclusion is itself a contradiction, absurdity, or falsehood derived from the initial claim. You can try to put that into practice and annoy your friends and relatives. Have fun!

How does any photon reach exactly the energy needed to excite a particular atom?

I know that quantum mechanics states that some things, like bumping an electron to a higher energy level, requires something like a photon to have juuuuust the right energy for the electron to 'accept' that photon and then rise to the higher energy level. But it is always explained that it has to be exact. Like, EXACT exact. It must be, let's say, 10,854.7952 electron volts, which corresponds to a frequency of 12.795832 GHz (ignore the actual values, I just pulled some numbers out of my head). It is always explained that if it were even slightly higher or lower than that amount of energy, the electron wouldn't be excited by it. Well, what are the odds that a photon with that very very VERY exact energy level would come passing by in any reasonable amount of time? I know photons are a tiny amount of energy and there are a huge number of them all the time, but still, it seems like such a precise requirement would be very restrictive, and would result in almost no interactions between particles and the EM force. It seems like all my assumptions can't be right here. What am I missing?

There's a relationship between the uncertainty in the energy of an excited state and the lifetime of that state. This creates the "natural linewidth" of a spectral line. The fundamental broadening of a spectroscopic line that cannot be narrowed by any sort of improved spectrometer design because it's just due to the Heisenberg uncertainty principle. In essence the shorter the lifetime of a state, the less precise the energy of that state. But no matter what there is always some fundamental breadth to the energy spectrum.

[Marvel] Are Marvel heroes that hated and feared that they mistake appreciation for oppression?

In a DC/Marvel crossover, the Marvel heroes were getting autographs and praise for their heroics in the DC universe, and found out that DC's heroes were getting statues and museums in their name. Captain America apparently found it disgusting and believed that the DC heroes were forcing people to love them. Does that imply that the Marvel heroes are so used to being constantly hated and feared that they can't grasp the concept of people actually showing appreciation for their heroic deeds? Also, does Captain America presenting this belief imply that on that Marvel universe, the Avengers are public pariahs in a similar vein to Spider-Man or the X-Men?

There's appreciating you and then there's building multiple full-size museums for the specific purpose of teaching people how great you are. People don't just love the Justice League. They *really* love the Justice League. They have statues everywhere and regular parades and are allowed to supersede the sovereignty of nations based on sheer trust. A lot of people genuinely consider Superman *literally flawless*. If you only just found this out, you don't have to be a self-loathing paranoiac to suspect something is wrong here.

ELI5: How does Chik-Fil-A not struggle financially relative to other fast food franchises, considering they are open one day less than all the other businesses (They are closed on Sundays)?

That also reduces their costs (not rent, but cleaning, upkeep, etc...). The key metric isn't just absolute amount of money they make, but amount of return on the money they spend, and they do quite well on that score.

ELI5: How do clear sunglasses work?

Are clear sunglasses better or worse than traditional sunglasses?

The medical purpose off sunglasses is to protect your eyes from UV radiation. The secondary purpose is to give your eyes rest from bright light. While traditional sunglasses have dark glasses, this is not necessary to block UV light. The purpose of the dark glasses is to give your eyes some rest so you don't get bothered by reflecting surfaces or the bright light itself. The problem is that while some cheap sunglasses might give your eyes this comfort they do not always block the UV radiation. Thus still letting it damage and possibly burn your eyes. So to come back on your question: Clear sunglasses are healthier for your eyes than cheap normal sunglasses because they are specifically designed to block UV light. Though they will not give your eyes relief from the bright light so they're worse for tasks that need your focus and attention (like driving for example).

Why was cephalization an evolutionary advantage? Did quicker information processing between senses outweigh the chances that multiple nervous centers could be destroyed at once?

One key concept to remember in evolutionary biology: the search space for potential adaptations is effectively infinite, so you will almost never find the "best" solution for any problem. What you tend to find is the first serviceable solution, which is then improvised upon and gradually improved. Whether or not cephalization is "best", it probably has some evolutionary advantages of simplicity. Is it easier to make 5 separate brains, or is it easier to just have one brain grow much bigger? Probably the one-brain solution. Once you've got a single big brain, is it easier to make that one big brain smarter? Or is it easier to break it all and start over trying to develop a distributed brain? Almost certainly better to just improve on the already-existing brain. The advantages for processing speed for a centralized brain may be incidental, or they could be the driving force, it's pretty hard to say and might need some complicated modeling to see if one method is much better or not. Even if the distributed model were better, it would be starting at square one right now. It would be hopelessly un-evolved and would be badly outgunned when competing against smart and aggressive cephalized animals.

ELI5: if cancer is basically a clump of cells that dont want to die, why/how do things like cigarettes, asbestos, and the literal sun trigger it?

Cancer cells result from mutations that disable the things that keep cell growth in check. Those mutations come from incorrect repairs to cell DNA, and those errors happen more frequently the more repairs take place. Therefore things that cause damage that requires repairs increase the chances of developing cancer, stuff like cigarettes, asbestos, and sun exposure.

ELI5: Microsfot .NET framework and what it does

I cant wrap my head around what Microsoft .net is and what it provides someone please help

When a computer program is written, it is usually in a language that can be read and understood by humans. For the program to run, it must be translated into code that the machine (particularly the processor) must understand. If you want to run your program on a different type of processor, or a different environment (for example a different OS, or a mobile device, or the web) then it has to be compiled again, and usually substantially rewritten before that can happen. There have been attempts to solve his multiplatform issue, notably Java. A program written in Java is not compiled to machine code, but to "bytecode" that is then run by another program (a virtual machine) .NET is microsofts answer to this problem (and a competitor to Java), although it can use muliple languages (C#, VB, C++, etc). Programs written in a .NET language can be used in any platform that supports the .NET framework. Typically these are Microsoft platforms, like Windows Xp/7/8, or Windows Phone, or Microsofts web platform, ASP.NET. There is an open source implemenation of .NET however called Mono that allows .NET programs to run on Apple and android computers and devices.

Are there any philosophers who deal extensively with themes of whether knowledge is valuable enough to justify suffering?

Now for the context behind me having asked this question, I know some stuff that caused me to suffer immensely. However, as a result of the passage of time, I have come to be grateful for that which I know, even if I did suffer profoundly upon learning this information. So I am interested in whether or not any notable philosophers wrote/spoke about the value of knowledge as opposed to the value of ignorant happiness, either long or short term. I am especially but nowhere near exclusively interested in enlightenment and post-enlightenment philosophers for this post. And yes, I am aware of the allegory of the cave, I'm looking for some other examples.

John Stuart Mill was a philosopher who has a famous quote: “It is better to be a human being dissatisfied than a pig satisfied; better to be Socrates dissatisfied than a fool satisfied.” You can look into his work on utilitarianism and ranking of pleasures for more details.

Question about downvoting

The downvoting guideline says: >downvote only those comments which detract from the discussion (distracting memes, off-topic jokes, pseudo-scientific mumbo-jumbo, and anti-science rhetoric). What about wrong answers? If we are almost positive that an answer is false, should we downvote?

I think a more objective and probably more effective way to handle wrong answers would be to provide a constructive answer in response to the wrong answer detailing why they are wrong but providing a more correct answer. Instead of down voting them, just don't vote at all.

ELI5: I keep seeing antioxidant foods portrayed as good and healthy, but what are oxidants and why is oxidation bad for the body?

And are there any benefits to oxidants?

Many necessary biological processes create atoms or molecules called radicals. A radical is an atom or molecule that has an unbound valence electron. That electron wants to become bound. In doing so, it can cause damage to parts of our cells, including DNA (look up the free radical theory of aging). Oxidants are a type of radical, usually either a single oxygen atom or a hydroxyl radical. Anti-oxidants bind with these radicals and neutralize them

ELI5: Eye Color Genetics

ELI5: My mom has green eyes, my dad (RIP) had blue eyes. I also have blue eyes, but my sister has brown eyes. I understand basic eye color genetics (blue and green eyes are recessive, brown are dominant) but how can two parents with recessive eye color traits have a kid (my sister) with a dominant eye color trait? No, she is not adopted, theres no scandal here. No milkmans baby or anything like that as far as I know. Is this possible? Please ELI5, thanks.

Eye colors are a bit more complicated. There's a separate set of genes that controls how melanin (the protein making your eyes brown) is packaged. If this gene is mutated (double recessive), you will have light colored eyes even if you have the dominant brown eyes gene. For example, let's say P is dominant good packaging and p is mutated bad packaging. B is dominant brown eye and b is blue eyes. You need at least one capital P and capital B to have brown eyes. If your mom was Ppbb (blue eye due to two recessive color) and your dad is ppBb (blue eye due to mutated packaging), your sister with PbBb would have brown eyes with a 25% chance! The other 75% chance would have blue eyes.

[Cars 2]When Mater supposedly leaks oil, the other cars react as though he wet himself. Considering how important oil is to an engine, shouldn’t they be acting like he’s bleeding out?

Both gas and oil appear to be consumed as foodstuffs, as you can get both at "Flo's Gas and Go". (Lightning refills there during his stay, and Sheriff grabs some oil when he's "feeling a quart low".) As for the severity of oil loss, we regularly see junker cars being unable to run on their own, or even having their jaws completely rust off. Neither of these cases appear to disturb the cars themselves or others. It's unclear exactly what constitutes a car's death, like in the case of Doc Hudson, but breakdown and/or dismemberment don't appear to factor into it.

What books should I read to learn how to take apart arguments better?

I want to know to be better at finding my own biases and and assumptions and other people's too, but since I have no one that wants to engage in debates over beliefs that are outside politics I wanted to read something like Discourses or books that state a methodology to analyse and take apart ideas and arguments.

It also helps to learn by simply doing. Oftentimes, you don't increase critical thinking or reading comprehension by reading a book about critical thinking or reading comprehension. These skills simply "emerge" out of close engagement with good work. Try reading any good work of philosophy, and then working out what exactly the claims are. You can even post here, and more experienced philosophers will help guide you if and when you go wrong. (It may also be helpful to read papers that were written more recently.) For example, you can read something like Shelly Kagan's "What's wrong with speciesism?" to see if you can figure out what the thesis is. You can do the same with a paper like Susan Wolff's "Moral Saints". Try to see if you can distill the thesis down to a single proposition. Or, try Sharon Street's "In Defense of Future Tuesday Indifference". Really try to figure out what the essential claims and argumentative strategies are.

At what size of a particle does classical physics stop being relevant and quantum physics starts being relevant? Why?

Classical physics starts deviating significantly at the molecular level, so on the magnitude of ~10^-8 m. There is no clear boundary between classical and quantum mechanics, it's more of a continuous transition. With that said, quantum mechanics can be used to predict phenomena on a larger scale, it's just that classical physics approximates it so well that they're basically identical.

ELI5 Why does something soaked in water appear darker than it's dry counterpart.

It just occurred to me yesterday, other than maybe "wet things absorb more light" that I really have no idea. Just a few examples: - Sweat patches on a grey t-shirt are dark grey. - Rain on the road, or bricks end up a darker colour. - (one that made me think of this) my old suede trainers which now appear lighter and washed out, look nearly new again once wet, causing the colour goes dark.

Wet objects aren't darker: they're *more transparent*. Put a spot of water on a piece of paper and look down on it: the wet spot looks darker than the rest of the paper. Now hold it up to the light: it looks brighter! See /u/Flavored_Teeth 's answer: when light strikes a fibrous or granular surface like cloth, paper, or dirt, it bounces off the surfaces of all those fibers or grains, ping-pongs around a bit, and eventually much of the light bounces back out to your eyes. As a result, these surfaces look light-colored. But if you add water, you reduce the reflection off the fibers or grains (because the difference in index of refraction between the material and water is less than the material and air). So the light penetrates deeper, is more likely to be absorbed or pass completely through rather than bouncing back out. Most of the time when we look at things, both we and the light source are above the material, so dry things look brighter, wet things look darker. But if the material is between us and the light source, it's the other way around.

ELI5: How do modern day 'hackers' learn to do what they do best?

It seems everywhere I go you can see news clips about someone who has 'hacked' into a major system or found a new way past some firewall. I know it's not as it's depicted in movies, and programming language is an important pre-requisite, yet nowhere i look can you find a starting point or decent program for someone interested in doing it. EDIT: Thank you for all of the replies, i appreciate it. Now I've been surfing around some threads and what not, lo and behold i'm learning something bout programming.

How do they learn? Trial and error and spending a lot of time analyzing even the most asinine elements. Looking at what others have built and seeing "patterns" hacking is basically software engineering but in reverse. So really ANY software class/textbook is a good place to start.

[Harry Potter] Why aren't snakes considered "beings"?

In the *Harry Potter* universe, there are two categories of magical creatures-- "beasts" and "beings". "Beings", broadly speaking, are creatures that are intelligent enough to communicate with humans in some fashion, and can use their intelligence to participate meaningfully in Wizarding society. Such creatures include goblins, house-elves, hags, vampires, giants. Merpeople and centaurs are exceptions, as they do not wish to involve themselves in the affairs of other species and declined "being" status. So that brings us to the issue of parselmouths. In the world of *Harry Potter,* parselmouths are wizards who can speak to snakes. Obviously, in our world, snakes are not especially intelligent, so it would be difficult to speak with one even if you could understand their "language". But parselmouths are clearly able to have complex and meaningful conversations with snakes. This shows that snakes in the *Harry Potter* universe are much more intelligent than snakes in our world-- they have a language, and they can hold conversations with humans. So with all that in mind, why are snakes not classified as "beings"? They cannot speak normal human languages, but neither can mer-folk, and they were offered "being" status.

Sapience isn't enough to be considered a being, you need to be able to rise above your baser insticts to participate in society. The Textbook Fantastic Beasts and Where to find them by Newt Scamander explicitly states this as the reason why Acromantulas Manticores and Sphinxes aren't considered beings, since despite their human like intelligence, they still would not be able to resist attacking humans in specific circumstances.

ELI5: Why I can memorize complicated formulas, but I struggle with knowing what letter comes next in the alphabet without singing it?

The alphabet is stored inside your memory in a way similar to how you store complicated formulas. Have you ever tried to write down a formula backwards from memory without recalling the formula? Or have you tried rewriting the formula solving for one variable without writing out the original formula first? We've learned how to parse through these formulas a certain way so they stick. If we try and parse them differently, it's much more difficult. With training, it's much easier to recall the alphabet (imagine if you have to file things alphabetically all day). However, if you don't have to do it too often, your mind is not as trained to compare letters.

ELI5: How does dunking a hot metal in cold liquid make it harder?

Iron and steel can have a variety of different internal structures - the exact nature of the structure you get depends on a few things, but in iron and steel two of the things that have the biggest influence are carbon content and temperature. Carbon content is a relatively easy one to alter, as it doesn't change significantly as the metal cools, but what can you do if you've got a desirable internal structure that's present only at high temperatures? You can quench the metal... that's what. This rapid cooling means that the transition from the desirable structure to less desirable (i.e. softer) structures doesn't happen to the same extent, and so you end up locking in a structure that you'd normally only see at a much higher temperature in a metal that's now at room temperature.

ELI5: Difference between character progression and character development.

It would be great if you could provide some examples from well known fiction.

Character developement basically means that a character gets fleshed out, whereas character progression means that a character changes. I'll give examples from Harry Potter, since it's a fairly well-known story. Dumbledore doesn't have much character progression, his character is pretty much the same at the end of the story as it started out. However, he has a good amount of character developement, as we get to know his world view and his motivations, for example. Harry himself on the other hand gets more character progression than character developement - the story is more about him coming of age than it is about exploring his character. Not that he's undeveloped of course, but it's less of a focus for him. Essentially, characters progress, but they are developed. Note though that character progression is often wrongly used interchangably with character developement.

Why don't substances like hydrogen occasionally combust at 'low' temperatures due to the long tail of fast moving molecules?

If hydrogen starts to combust immediately at 900K why doesn't it eventually start to combust at lower temperatures, say 300K. Is it just incredibly unlikely that any molecule would be moving fast enough, or is there some other factor that determines when molecules react other than the kinetic energy with which they approach each other?

Chemical reactions have a minimum activation energy, i.e. the energy needed to result in a reaction. You may or may not have molecules which reach the kinetic energy required but it quickly gets redistributed - it's not a case where one molecule reaches the required energy and triggers a chain reaction. You need an appreciable number of molecules with energies equal to or higher than the activation energy for the reaction to occur.

Why is cancer so hard to cure?

Cancer research seems to get a ton of fundraising and support, but there is still no cure. And, how does one actually cure cancer? What would we need to discover?

1. There are many different kinds of cancer. 2. There are many different causes of cancer. 3. Current treatments require killing the cancer cells. You can't "fix" a tumor. 4. Cancer is mutated human cells. Your body doesn't know they're harmful. 5. The cancer cells don't commit suicide like normal cells. 6. It grows uncontrollably. 7. It can break apart and grow more cancer elsewhere. 8. It can grow inside organs, causing them to malfunction. Think of the human body like a beautiful garden. There's a few weeds growing in the middle, though.(cancer cells) Your actions: A. Prevent more weed seeds from getting into the garden (Reducing cancer causes) B. Mulch the ground (Increase resistance to cell mutations) C. Prevent the weeds from spreading. D. Remove the weeds. (Cut out cancer cells) Saying "we have no cure" isn't exactly right. We have a cure for many of them, and prevention for others.

ELI5: Why do we begin to pick up accents after only being somewhere new for a short period of time

For example, my friends are from the North and went to Florida for Spring Break -- after only a couple days a couple of my buddies unknowingly began using a southern dialect with a few of their words. I've done this too when I was in Sweden.

People naturally tend to do things to fit in with other people, even subconsciously. Accents make people stand out like sore thumbs, and you and your brain both know it. So, even after a short period of time, you just kind of start speaking like those in your environment.

ELI5: When someone uses these brackets [] in journalism?

Alright so lets say for example "[He] went to the corner store to get a chocolate bar, it wasn't much later until he realized he didn't have change in his pocket" Why do they always put a particular noun in those square brackets like that? I hope this makes sense, if not I can provide a link to an article using this...

When you quote someone, sometimes it may not be clear what is being talked about without including other parts of the quote that aren't otherwise needed. The brackets are used to clarify what is being talked about in a quote while making it clear that the words within are not actually the original speaker's words.

When and why do social scientists use log scales

I noticed that in some instances (the popular science talks on why we might not be doomed by Hans Rosling, stick out for me) data like global income distribution is represented using a log scale. Now I know that it makes sense to use log scale for doing stuff like plotting the progress of an exponential process. But what are other reasons to use one, like in the casw as above?

Log scales are useful for describing phenomena where changes occur mainly multiplicatively instead of additively. To construct a silly example, let's say we're playing a gambling game where everyone flips a coin and if they win, they gain $10, otherwise they lose $10. If you wanted to plot the final distribution of winnings, a linear scale is appropriate. If you played for 10 rounds, the largest possible value (if everyone starts at $0) is $100, so you can imagine a histogram with x-ticks for each $10. If instead, the gambling game had you double your money if you won, and halve your money if you lost, then with 10 rounds if you start with $1 then the largest possible winnings is 2^10. If you wanted to depict the actual winnings value, again a linear scale is appropriate, but if you wanted to depict the number of win events minus the number of loss events, then a log scale is appropriate, with base 2. In a log scale, the largest x-tick would be 10, representing 10 wins and 0 losses. Many real-world phenomena increase/decrease multiplicatively rather than linearly (ie, many real-world phenomena are described well by exponential functions), and log scale plots are useful for depicting multiplicatively changing phenomena when you care more about the number of "change events" rather than the actual value. It turns out this is often the case, so log-plots are quite useful.

Why do antigen rapid tests not work after 15 minutes?

I've used two different types of antigen rapid tests. Both say that the results aren't valid if more than fifteen minutes have past since testing (dropping the solution onto the test kit.). Why is this so? Do the coloring/colored molecules that do the binding no longer work, or weaken, after 15 minutes? Or does a positive turn into a negative?

These tests work by detecting the virus with manufactured antibodies that recognize some specific feature of the virus, like the infamous spike protein. There are two antibodies that together form a sandwich around the antigen (the feature the antibodies are looking for). The sandwich is formed when all the parts come together like a lock and key, or ball and cup. It’s very similar to an enzymatic reaction in that everything matches both physically (like the grooves in a key and the pins of the lock), but also electromagnetically - sometimes there are concentrations of positive charges that expect to meet negative charges (and vice versa) in these components that fit together. So the better the fit, the more obvious and fast the reaction. Where the fit is good, the test can be considered positive because all those antigen-antibody sandwiches are present in a high concentration (and therefore visible as a line on the test). However, over time, these sandwiches will still continue to form even in the absence of one of the components (even in the absence of the antigen), because positive and negative charges are so drawn to each other. They make a bad, but detectable, reaction. Because this isn’t an ideal sandwich, it happens slowly, very slowly, compared to a true positive. That’s why they give a cut-off time to the test - eventually it’s going to turn positive, but the speed at which it does is the telling part.

In my understanding of existentialism, man is meant to live authentically and adhere to his own moral code. Therefore is it justified for a man to kill another or commit some sort of crime because it is what he thinks is right?

The main work of Existentialist ethics is de Beauvoir's *The Ethics of Ambiguity*. She suggests that, no, one ought not to go around being a shithead, which includes not murdering people, because the freedom of others provides the basis for a moral system which rules out (among other things) murder. Sartre (another key Existentialist) agreed with de Beauvoir.

ELI5: How does tinting work where you can see out but people can’t see in?

Let's just look at normal transparent windows. They let light through but they also reflect light. Let's look at the windows of a house, during the day sunlight is very bright so the outside is bright. In the house even if you have a light on it s quite dark compared to the outside and as a result, when you look at a window it is very hard to see what is inside because the daylight the window reflect is a lot brighter light from the inside. It is also easy to see out of the house because the light coming through the window is brighter the reflected internal light No compare it to the night with the light on in the house by very dark outside. The condition is now reversed, it is easy to see in but from the inside, it is reflected internal light that is dominant so it is hard to see out. Lets look at a car tinted window will result in less light passing trough the window and alos reflect more light back. So the inside of the car is darker and more light is reflected and it is very hard to see in during the day. Even at night you usually do not have any significant amount of light source in the car so but there is light outside from streetlights, car headlights etc so the inside is still darker then the outside, If you have a car with a tinted window and someone has a bright light inside during the night it can be bright in the car and now you can see it but it is had to see out. If you want to see what is inside a parked car with tinted windows take a flashlight and push it against the window and try to block any light reflection with your hand around it. Now the inside is brighter than the outside and you can see it. This works for building too. You can see through them during the day too, put you heat close to the window and block light from reach the glass around you head with you hand or even better some pice of clothing, Not there you have create a darker area for you head and it is the inside that is brighter and you can see int This is also how one-way mirror works, You have a mirror that reflects some light and lets something. Then you can see from the darker room to the brighter room but not the other way. The flashlight trick and putting you head towards the mirror with blocked light woks here too

Can you point me toward some sources that discuss the "normalization" of white experiences?

(xpost from /r/askhistorians) I'm a high school teacher. A student of mine is writing a paper arguing that the "standard narrative" of women in the workplace -- that the labor needs of WWII brought women in and changed cultural mores about their participation -- overlooks the experiences of black women, who had been working outside the home in large numbers since Reconstruction. She'd like to talk about the problem of "normalizing" the experiences of white women, by which she means assuming that white experience is the "default" or "normal" experience, such that the story of white women becomes in popular understanding the story of women as a whole. I am trying to help her by locating sources that will discuss that issue, but I don't know where to look, and "normalize" doesn't seem to be the right term for this sort of discussion. Any help would be appreciated. Thanks.

Nell Irvin Painter's The History of White People documents the history of the concept of whiteness from the early modern era to the present. The whole thing might be too big for one high school paper, but you can probably pick out useful chapters if you want to use it.

[General sci fi] Things like Xenomorphs or Cell are said to be perfect, in a biological sense. What would a structurally/biologically perfect creature actually look/behave/act like, and what sort of traits would it have?

Title. A lot of sci-fi claims to have a "perfect lifeform" in it, but what would a perfect lifeform actually look like? How would it be structured? What biological abilities would it have? How would it act and behave? I get that "perfect" is subjective, so I'll leave the exact definition up to you, but I think ou get the general idea behind the "perfect lifeform" concept and question.

Perfect isn't really subjective, it's just highly variable based on the function that they need to perform. Every species alive can be said to be "perfect" for their existence in their biological niche. The Woodpecker is perfect for getting grubs out of trees in its habitat with its prey with its predators with its reproductive method with its... However, we look a lot more for versatility. Can it survive and thrive when those things are not there. With that, the perfect creature are the Star-Children from 2001: a Space Odysee. This is a species that rejected all the imperfections of biology and moved on to pure electromagnetism. They possess near infinite ability. We saw them with a flick of their physical manifestations, the monoliths, turn Jupiter into a star just to cradle the infant life on one of its moons. They gave us something many currently attribute to a god, the power to reason, the knowledge of good and evil. They did it by just dropping one of their monoliths nearby. They are the closest thing to perfection that can still be called a creature and not a God.

ELI5: Why is Daylight Savings Time still a thing??

I've heard some explanations for why it started, which all made sense for back then, but why do we still do it?? Are there any present-day benefits that are worth the effort and confusion?

The main benefit is to be awake during more of the daylight. If it gets dark at 7 and the average person goes to bed at 11, that is 4 hours they are using electricity for lighting. If instead it gets dark at 8, then that is 25% less electricity they use for light.

How did the new island appear from the sea in Pakistan?

Earthquakes occur when there is sudden motion on a locked fault to relieve built up stresses. Here, slip on the fault strained (displaced relative to the natural position) the nearby seabed, causing it to rise 5-10 m. The now-exposed rocky body was formerly a shallow rock body (less than 5-10 m below the surface). It was simply elevated slightly by motion on the fault.

In a conflict, side B uses morally wrong tactics (slavery, firebombing, nukes). Side A condemns these practices yet justifies using the same tactics because they are used for the sake of defeating this "evil". In this scenario is Side A just as "evil" as side B for using the same "evil" tactics?

Some historical examples that made me think of this question: In the US civil war, border states were allowed to keep their slaves and helped the Union war effort against the slave-owning Confederacy. This is assuming that slave labor helped in the war effort of the Union army. In WWII, war crimes were committed by both axis and allied forces. Do the evils of the Nazi war machine and imperialist Japan justify the use of firebombing and nuclear weapons? I understand that this question may be heavily context-dependent, but I would appreciate any feedback or other examples of this kind of situation. thx

Both sides will claim their tactics are either moral, or necessary to achieve a greater good, and therefore morally acceptable. I follow Bertrand Russell here. Opposed to war in principle (jailed during ww1), still, in confronting Hitler he said "War is always a great evil, but in some particularly extreme circumstances, it becomes the lesser of two evils." With this, we are forced to look at the end result of not using necessary means to defeat an opponent: will the result of the war be moral, or immoral. If immoral, the weapons of war become a short term lesser evil to overcome a long-term greater evil.

ELI5: How do big companies/colleges maintain high internet speeds across hundreds of people's devices?

It was a random thought that occurred to me. I've heard about how connecting a ton of active devices to a home network can cause congestion (and slow it down?). I'm a university student and I am always able to have a fast internet connection even when there's hundreds of people in the same building as me using the network.

Your building has lots and lots of access points all connected to many, many switches. Each switch is likely to be able to handle a Gbit of traffic *on each port* so for a 24 port switch that's a 24+ GBit back plane. Your college also has an industrial level internet connection. And if its a large research institution it likely is a node on Internet2 which is an all fiber network that connects lots of colleges and other institutions. When you data needs to get to one of those institutions, it gets automatically routed over the super fast fiber connection.

ELI5:Why do large companies advertise when they have nothing that can be purchased by normal consumers? (i.e. Boeing)

Primarily, to keep their name in the industry, and to attract employees. Boeing also manufacturers trains, likely a larger part of their business financially than the aeroplanes. By keeping their name up there, cities are more likely to buy Boeing trains for their subways. Simply: Just because they aren't on the "normal consumer" market doesn't mean that there isn't a "massive consumer" market looking for their products, and advertising doesn't know borders.

CMV: If you say you need to be true to yourself, you're doomed for unhappiness when it comes to relationships.

I have a good friend who lacks compassion. He insists he needs to be true to himself and do what he feels right, even if it means the woman he loves might be repeatedly unhappy with his actions and leave him. He is unable to see that in order for good relationships to prosper, each party needs to be heard and open to one another's perspectives, even if they might not agree. If he had compassion, he could weigh the needs of his girlfriend and his own, then try to incorporate them both into his actions. I get that it's important to act true to yourself when making solitary decisions. Once you're in a committed relationship, for someone to say they need to be true to themselves, it becomes a one-sided argument. This belief completely shuts down the lines of communication and shifts the dynamic between two people with valued opinions to that of just one perspective with no room for the other. The conversation is over. This behavior seems to be sabotaging the likelihood of any lasting relationships.

Being true to yourself means don't compromise your identity, your values, and don't be someone you're not to please other people. It does not mean, however, that you ought to do whatever the fuck you want. It doesn't mean your way or the highway. That's not being true to yourself. That's being an asshole.

ELI5:The Pyramid Scheme and how they trick you into it?

A pyramid scheme is one in which a person or organization convinces their potential employees that in addition to selling a project and making money, they will get a portion of the profits from any new employees they recruit. It is called a "pyramid scheme" because a very small minority at the top are drawing profits from everyone they hired, everyone their employees hired, everyone that those people hired, etc, which can be modeled to look like a pyramid with many stones at the bottom and very few at the top. Were a pyramid scheme a legitimate business then there would have to be opportunity for UNLIMITED growth on an exponential scale. That's not the end of it though, because all employees have to purchase the product to sell from their superiors in the company. This way the employees have to pay to even have a chance at making profit. People get roped in because they don't understand the concept or because they don't realize that you shouldn't have to pay like they do to become employed with a company.

ELI5 Why do we eat plants if we can't digest cellulose, ie, plant cell wall?

Title says all. Plant cells are covered by cell wall made of cellulose. The human body doesn't have the enzyme cellulase to digest it, so why do we eat them? Do they just pass through us? If so, why are they 'healthy'?

Because we can get a variety of other vitamins and nutrients from them. There isn’t much in the cell wall for us to get, so it just passes through. Overall, plants are healthy for all the nutrients we get and the cellulose doesn’t hurt us.

Are there any harmful effects of school uniforms?

Influencing the perceptions of masculinity and femininity in developing children (so another process of gender socialisation that promotes traditional gender norms) as well promoting a binary gender classification. - Happel, A., 2013, Ritualized girling: School uniforms and the compulsory performance of gender, *Journal of Gender Studies*, 22(1): 92-96.

Why doesn’t electric resonance imaging/ nuclear electric resonance exist/work?

Magnetic resonance imaging (MRI) and nuclear magnetic resonance (NMR) are both powerful medical and biochemical tools. From what I understand both rely on the magnetic spin properties of particles, can a similar principle work with the electric charge inherent in particles? Why/why not?

>can a similar principle work with the electric charge inherent in particles? In principle you could do something similar with particles with *electric dipole moments*, but those are strongly suppressed by time-reversal symmetry. Magnetic dipole moments don't violate time-reversal, so they're very common in atoms and molecules, while electric dipole moments are somewhere between extremely small and zero.

As oxygen is produced by photosynthesis, is the proportion of atmospheric oxygen lower in urban centers? If so, how much lower, and does it affect human health?

It seems logical that it would be. I did some research myself using University of Google, but so much of what I found was from unreliable quack health sites that I thought I'd ask the experts. :)

Yes it does, but if you measure it accurately, you will find that there will be more oxygen near water and on water compared to land, due to algae and photosynthesizing bacteria, and especially phytoplankton which produce quite a considerable sum of oxygen. However, the proportions of oxygen in cities to countryside vary so much as you have to take into account a whole range of factors, including, and not limited to: pollution by cars, industry, people, buildings, materials in the city, bodies of water, temperature, wind etc. and is the reason why you will never get a exact answer, because it is so variable.

[Star Trek] How do officers from Starfleet and other races understand how to use foreign computer systems almost immediately?

There are some exceptions, like when Data had to work out how to use a computer. And when the DS9 crew spent a while training to learn the Jem Ha'dar system. But for the most part they seem to be able to walk straight onto a ship of a species they've never encountered and know how to use a system they've never seen before, in a language they've never seen before. They must get training to be able to interpret systems, but even so, most of the time they seem to immediately pick it up.

At the turn of the 21st century earth had already amassed dozens of computer programming languages, hardware schemas, database structures, and other complex computer systems. By the 23rd century, imagine how many more distinct systems that humanity alone must have designed. Starfleet has access to not just all of human computer science, but also the other worlds of the Federation, some of which have had spaceflight longer than humanity had civilization. At the end of even a basic introductory course at Starfleet Academy, a student would have exposure to hundreds of different programming languages, user interface schemes, data structure formats, and hardware designs. This would probably make them *pretty darn good* at mastering some random thing they happen to stumble upon. Also, it is not difficult to imagine that part of Starfleet engineering coursework is comparing and contrasting different approaches that the dozens of civilizations have used to solve essentially the same problem: *how not to die in the hostile, unforgiving environment of space*.

ELI5: Why is it so difficult to turn sea water in to drinkable water?

It is not difficult, reverse osmosis works exceptionally well. But.... it takes a lot of energy to run the pumps, and it takes water to back-flush system. Energy = $$$$. Most desalination plants are conveniently located near power plants for this reason.

Why don't mRNA vaccines require an adjuvant?

Most other vaccine types, especially the inactivated virus/bacteria or subunit vaccines require the co-administration of an adjuvant to elicit a good immune response leading to immunity. Vector vaccines, to my knowledge, also contain an "adjuvant" in the form of the actual virus used to deliver the DNA to cells. mRNA vaccines do not seem to require an adjuvant, and in fact the most successful mRNA vaccines have modifications on the RNA portion to *reduce* immunogenicity. Why is this? Do the RNA and lipids used in the vaccine have properties that somehow allow the immune system to decisively react to them, or their translation products, as "foreign" antigens? ETA: I understand how general immunology and innate immunity works (I have been an MSc. structural biologist for ~10 years) with regards to MHC and TLR pathways, but I don't understand the molecular mechanism of *why* our immune systems seem to respond so effectively to 'intercellular' pathogens (eg. extracellularly expressed antigen subunits) as opposed to 'intracellular' antigens like protein/ protein subunits from vaccines without an adjuvant (although we do not seem to have this 'problem' during natural bacterial or fungal infections, presumably due to the abundance of immunogenic molecules present in bacterial cell membrane lipids etc)

RNA itself has an adjuvant effect. Biontech mentions it in their presentation. It makes sense for the body to defend itself against foreign RNA, before they express any foreign proteins. There are so-called RNA sensors which are tightly regulated to prevent sensing of self-RNA. Toll-like receptors can sense RNA, there are also pattern recognition receptors in the cytosol.

[Astronomy] How do we determine where the edge of the sun is?

When reporting the radius of the sun, how do we know where it ends?

Generally, something known as "optical depth" is used. Optical depth is (more or less) the ratio between how much light is incident upon a barrier vs how much light actually gets through. The "surface" of the star is defined as the radius where that optical density reaches a certain value, typically 2/3. Edit: numerical accuracy

CMV: The US court system is a horrible, illogical system.

I don't know how anyone can defend the US court system. 1. The jury selection system ensures that a *biased* sample of the US population is chosen, because Americans are filtered out according to what Prosecutors/defenders believe are the "ideal" jurors. 2. The Jury size is always too small to be a statistically valid sample of the US population. The current system ensures the selected pool can be biased enough to meet whatever ends the prosecutor/defender desires. Why don't courts use a huge pool of jurors (say greater than 30) and then forget about jury selection? I think it's a right for all Americans to participate in our Court system, whether or not we are an "ideal jurist". If lawyers keep complaining about how biased jurors are.... why do we even use a jury system then??? I just don't understand how anyone can think a biased selection of 6-13 jurors (yes, only 6 people sometimes!!) can result in justice. 3. The obvious money imbalance in all Court cases ensures that every defendant and plaintiff will be treated better when they have more money. How the fuck can anyone support a system that lets people with better lawyers win more cases? How can anyone support a system that most obviously supports the rich against the poor? At least, why aren't there limits in place for how much money can be spent at the court house?? 4. "The US Court system sucks but is the best we got". I don't know, the Dutch and Germans and Norwegians all have different systems that people seem to be more happy with. Anyways, I think the US court system is a horrible travesty that is an insult to "Lady Justice" and the scales of balance. Then again, I'm an ignorant layman and not a lawyer and am not too familiar with the justice system anyways.

You do realize that if both the prosecutor and the defense attorney have a say in jury selection, then the process of that selection isn't biased since both legal sides have the opportunity to choose favorable jurors.

Is there a website to practise statistics methods like programmers do on leetcode?

I’ve always wished there was a website that was just tons of stats examples where you are given data, some background information, and a hypothesis and you have to run a test and report if the data support that hypothesis or not. And once you answer an example, it would share the correct answer along with an explanation/code of the best method for testing this specific example given the data.

ELI5: Why do words hurt?

I've just been thinking about it, and I'm genuinely curious why people can be so affected by them, is there an actual reason our brains take a nasty insult worse than a punch? And also why some people can easily shrug off insults, where it can completely break others.

Human are a social species. How others perceive us is very important to our future success and well-being. So, discovering that someone disrespects you is a somewhat serious problem. It's not the words themselves, it's what they imply about your status.

ELI5: What is "The Monster" in Group Theory?

I've seen a few videos online describing how mysterious "The Monster" is, and how it was even described as "The voice as god" by its discoverers. I don't have any experience with Group Theory or e8 lattices or whatever, this topic sounds cool and I just want to understand it further.

Group theory in some sense studies types of symmetry. For example, an equilateral triangle has a three fold symmetry whereas a square has a four fold symmetry. These symmetries are objectively different. Mathematicians were interested in knowing all the types of symmetries. So they categorized tons of them. Thing of symmetries as chemical compounds. It turns out that some symmetries are really composites of two simpler symmetries. Like 6 fold symmetry may really be a composite of 2 fold symmetry and 3 fold symmetry. It turns out that all all finite symmetries are really just compounds of a set list of simple symmetries. Simple symmetries are symmetries that cannot be broken down. So simple symmetries are like chemical elements of symmetry. The monster is a huge simple symmetry. Normally simple symmetries are much smaller. It is very unusual that such a large symmetry has no constituent components. It would be like there was a random element of astronomical size compared to the other elements like Oxygen and Carbon.

ELI5 Correlation vs. Causation

When looking at statistical data over a period of time, what does “correlation” mean? How is it different from “causation?”

In this context, correlation would mean that two things track with each other. If X goes up, so does Y, and if X goes down, so does Y. Not necessarily at the same rate. There is another type of correlation, called inverse correlation, that is where when one thing goes up, the other goes down, not necessarily at the same rate. X goes up, Y goes down and X goes down, Y goes up. Correlation is different from causation because from the data you can't tell that X causes Y, although it might. This is obvious when you realize that if X correlates with Y, the reverse is true, Y correlates with X, yet very rarely does X cause Y *and* Y cause X. As an example, sales of ice cream rise in the summer, as would deaths from drowning (because more people swim in the summer). So ice cream sales and drownings are correlated. But that does not mean that drowning causes ice cream sales, or ice cream causes drowning. **Edit: Added explanation of Inverse Correlation**

[General Cyber Punk] I am the benevolent president of a Megacorp in a world ruled by similar Megacorps. What can I do to to make the world a better place?

Massive corporations rule the world. They are powerful enough to do whatever they want. They regularly commit atrocities and crimes because no one is able to stop them. Their hired goons regularly wage war in the streets, they have massive influence over AI and the Internet and they regularly exploit the poor, using them for cruel, inhumane experiments. Even worse, this all takes place on an Earth that has been seriously depleted of much of its resources, so hunger and disease are rampant among the lower classes. I recently became an uber-powerful leader of a similar corporation that I started myself years ago, specializing in medicine, AI and cybernetics, weaponry, vehicles and food. Unlike my competitors, I want to do good in the world, not just make a profit and secure luxury for myself. What should I do? How can I help? Even more pressing, is there any way I can stop the abuses of my fellow companies without risking being assassinated by one of their assassin-bots?

Pour your energy into AI development and quantum computing. Have your researchers pour their expertise into developing an AI for administrating over a large organization, with emphasis on maintaining the happiness, relative freedom, and health of all citizens within that organization. Then set it loose. Either it forms a utopia, or kills us all. Either way, it's a lot better than eating cardboard under a megahighway while hiding from MegaCorp #4's rent enforcers.

ELI5: how does lip balm work?

Chapstick, Carmex, whatever. “Medicated lip balm”. It is a moisturizer for lips, and lips only, it says. Other moisturizers say keep away from lips (and eyes, obviously, but lips are specifically named as well). So what’s the story?

Most lip balms contain a humectant, which is something that helps to draw moisture from the air and creates a barrier to lock moisture in. This is great for lips because you use them all day. Lip skin is delicate and if your lips become too dry or cracked it might make it hard to talk and eat, which are two things that are pretty important for our survival. Using a lip balm on normal skin is a bad idea because the barrier doesn’t allow your skin to breathe properly. If you applied lip balm all over your face then started sweating the sweat would get stuck under the balm, rather than evaporating. When moisture and oils from your body mix under a barrier that stops oxygen from getting in, it creates an ideal environment for bacteria to grow. Too much bacteria and you can end up with pimples because your body produces white blood cells (pus) and inflammation (the redness of a pimple to try and prevent the bacteria from entering your body further. The strength of different types of moisturiser tends to relate to how often that part of the body is used. In order of use and strength: Lips are used a lot, so it’s okay to use a strong moisturiser on them because it’s unlikely to stay there for a whole day. We also use our hands a lot, wash them several times a day and we don’t normally cover them. Which means the skin loses moisture faster than the body can replace it. Hand creams tend to be quite thick and slimy so the protection lasts longer and has a better chance of getting into the tougher skin of your hands. Next, the skin on a face is almost always exposed. Our face moves and stretches a lot to allow us to make expressions, so a face moisturiser is like light but still fairly moisturising. Lastly, skin on the rest of your body like your back, legs and arms. These parts of you don’t get bent, stretched, washed or exposed to the sun and air as much. They are also covered by clothes a lot of the time. So they only need a light and thin moisturiser at most because your body can usually manage the moisture levels on its own under clothes.

ELI5: How do NASA and other space agencies prevent all the satellites orbiting the earth from crashing into each other? How do we launch rockets without smashing into the satellites?

Here is a simplified explanation. The space agencies (not just NASA) keep a very close watch on orbits. The paths of each satellite are quite predictable and many of them can be steered to correct the orbit. With a bit of planning, there are plenty of gaps. Here's why. What we call space starts about 100 miles up. Most satellites are in a range of about 100 miles to 22,500 miles up. To compare with something more familiar, aircraft usually have to be a minimum of 1000 feet apart in altitude. Even a small range from 100 miles to 200 miles up gives over 500 layers 1000 feet apart. Now consider that the satellites could be anywhere over the earth's surface, which is roughly 200,000,000,000 square miles. That's a lot of room.

ELI5: Why do humans take to music so well?

Unlike good food, socializing, and so on, I can't really see the immediate biological links between humans and music. Just to clarify, I know some variations have been posted about 2 years ago, but none of the answers really satisfactory. New explanations would be great! Thank you so much in advance.

I think it takes a scientific research to tell why we first get interested in music. However, after the deed is done, our need for more is probably psychological, because sounds will have the meaning we assign to them - and most of us like to revisit certain emotions which can only be brought about by these associations we have made.

Do fish get confused when a large current or flood displaces them somewhere far away?

There are many, many different species of fish and they all behave and react differently. There are territorial fish: Clown fish (of Finding Nemo fame) will go and find an anemone during adolescence, and then never leave the square metre around that again until they die. Being displaced would likely kill them, or they may move to a different anemone if they can find one quickly, but that is not the sort of experiment that people like to run. Lots other fish are on the move their entire life. Mackerel and tuna, many sharks, herring - a long list of fish that just follows the food, the currents and the temperature. They don't have a territory so displacing them would impact them less - though the impact would be nonzero because they would still notice a difference in the water quality.

ELI5: when you’re showering and the water suddenly turns icy cold or scalding hot for a few seconds before returning to its previous temperature, what’s happening?

Water temperature in the shower is determined by the mixing of cold water + hot water from the two different pipes in your house. If the water pressure suddenly changes, like for say someone flushes the toilet, the cold water pressure in the shower drops and the temperature increases. Most showers these days have valves designed to minimize this effect. Because suddenly having nothing but scalding water can be dangerous. The valve mechanically senses the drop in pressure and adjusts the pressure of the other pipe to compensate, but there's still a fluctuation in pressure and temperature change. It just isn't as bad as without the valve. Your valve might also be worn out.

How?/why?/is? United States Social Security program failing or going bankrupt?

In order to pay for all of its current liabilities, the social security trust fund must accumulate funds from payroll tax. Currently, the social security trust fund is spending more money than it is gaining in payroll tax revenues, and this trend is projected to continue. If nothing is done, then the trust fund will go insolvent.

ELI5: In survival/apocalyptic movies, people can survive by just eating insects alone. Is this true in real life?

People eat insects, and they can provide some useful calories and protein. But no human society has survived using insects as a major source of its calories, and for a very good reason. The amount of calories you gain by eating an insect is very small in proportion to the effort it takes to capture or cultivate it. In many cases it will burn more calories to harvest and prepare an insect for food than it provides in calories. So if you are going to spend time gathering a food resource, it's a very poor choice. But if you are starving and see an insect as a target of opportunity, eat it.

CMV: Academic exams should either not be timed, or have far less tight time limits.

Full disclosure, I may be biased on this topic as I have just been rejected from the university of my choice because my grade in one subject was not high enough, but this is an opinion I have virtually always held. I have always struggled with time in exams, during my GCSEs and A Levels (exams usually taken at 16 and 18 in the UK) I was deemed to require extra time, but I still struggled to finish exams within the time limits, mostly due to writing speed. All of my chosen subjects were essay-based, which made the time constraints seem bizarre to me. No historian would ever write an essay in an hour and half without access to sources, for example. Since high school and college level education is meant to be a stepping stone into university, it baffles me that such significant a constraint is applied with little to no relevance to actual academic practice. In one of my exams I had to write two essays as well as answers a few shorter questions. I was barely able to even start one of the essays simply because I couldn't write fast enough, which caused my overall grade to drop from a predicted A to a B. In essays I wrote for homework I almost always got an A or A*, since I was not required to finish them in 45 minutes. Indeed, finishing an essay in a short time is not usually a sign of proper a proper intellectual process in actual academia, so the time constraints seem entirely arbitrary and unnecessarily punishing. I can sort of understand why STEM subjects might require timed exams, since answers are usually either correct or incorrect, and writing speed is far less of a factor, but why should written essays in which the quality of the argument is what is being assessed treated the same way? They are fundamentally different skills. Time management is important in academia, but this is not on such a micro scale as in exams. Time management is usually most important for the planning of research and such, and meeting deadlines, not banging out a thesis within an hour.

Usually, high school and even undergrad level courses don’t aim to give you anything more than knowledge and familiarity with the subject matter. They want you to know the basics off the top of your head. For this, it’s actually helpful to have a time limit because it ensures that whatever you wrote is something you *do*, in fact, know off the top of your head, and can probably say during a casual conversation about the matter. You’re absolutely right that it doesn’t translate well towards actual academic work, but it’s not meant to. It’s meant to assess whether or not you have enough of a grasp on the material to recall it quickly and accurately when asked—like what you’d have to do if someone verbally asked about your thoughts.

Why don't we use the computer resources for mining cryptocurrencies on useful tasks, instead of hashing

In cryptocurrencies such as Bitcoin a Block is created by "proof of work", meaning millions(perhaps more) of servers are wasting their resources on solving hashes. What if a Block was instead created by utilizing these resources to do tasks, such as Grid jobs in grid computing, or how we use cloud computing. One example is to use these resources to do protein folding for cancer research. Im not sure what metric would decide when a Block has been mined, but I just thought this might be an interesting concept, if at all even possible.

One of the key points of a Proof of Work algorithm is that it's fairly difficult to complete, but takes much less work to verify. You'd have to find something useful to calculate that has both of those properties.

Is there any recorded evidence of ancient Indian philosophers interacting with the pre-Socratic Greek and Italian philosophers?

Hi! I am from India and I started reading Anthony Kenny's The New History of Western Philosophy. I am reading about the pre-Socratic philosophers as of now and it seems that a few things are very similar to what we have in Indian mythology and philosophy. Like, the concept of atomism in Indian philosophy predates Democritus' atomism. Similarly, Pythagoras' theory of metempsychosis sounds similar to the idea of reincarnation of soul that we have in Hinduism. I know that it's entirely possible that two different civilizations might have come up with these ideas on their own but do we have any recorded evidence where the philosophers of these civilizations ever interacted with each other?

> do we have any recorded evidence where the philosophers of these civilizations ever interacted with each other? Nope. The earliest record of such contact comes with the expeditions of Alexander the Great, some time later than the period you're asking about -- and the details of even this record are sketchy enough that scholars are divided on its significance. This isn't to say that there wasn't contact, of course. But assertions of such contact remain speculative.

ELI5: Eristothenes measured the circumference of the earth by measuring the shadow of two poles, miles apart, at the exact same time. So how did he know the poles were being measured at exactly the same time in an era when people used the sun for timekeeping?

By doing it at local apparent noon. This is, by definition, the time of day when the sun reaches its highest point in the sky. If 2 places are on the exact same line of longitude (i.e., directly north and south of each other), local apparent noon will occur at exactly the same time in both places. You can, of course, measure this with a sundial. It turns out that while close, Alexandria and Syene (modern day Aswan) are not directly north and south of each other, which introduced some error into his calculations. Still, they're close enough that his measurement was remarkably close to the correct value.

If quantum entanglement can't be used to transmit information, then how is this experiment (see description for link) possible?

Been catching up on some reading, came across [this experiment](http://www.nature.com/news/entangled-photons-make-a-picture-from-a-paradox-1.15781) here. I've been told over and over again that entanglement can't be used to transmit information. So how the heck does this work? Aren't they extracting or inferring information about one photon's path from its entangled twin's behavior -- the exact sort of thing I've been told isn't possible?

Quantum entanglement can't be used to transmit information faster **than the speed of light**, but you can still do all sorts of things with it. There isn't anything in the article implying that they transmitted information faster.

Why do certain sounds sound appealing and others don't?

Three incomplete explanations: 1. A sound can be appealing because it is associated with a pleasant experience. If you grew up near the ocean, for example, a distant foghorn might be a pleasant sound. 2. As for the quality of sound, it might be that we are born appreciating certain sounds that are associated with well-being or survival, such as kind human voices or trickling water. Both could indicate safety and security. 3. In music, we tend to appreciate certain harmonies. These tend to feature a moderate amount of dissonance. Two tones played in unison (both the same tone) sounds nice but is uninteresting, as the frequencies (as measured in Hertz) have a simple 1:1 ratio. An octave has a 1:2 ratio and sound a little more colorful. Other harmonies have more complex ratios like 2:3, 3:5, etc. These are more colorful still. As the ratios get more complex they start to sound sad, and then eventually hideous. The most complex ratio within an octave on a piano keyboard is 45:32, known as a tritone. It sounds very "ugly". To hear a tritone, play the notes C and F# simultaneously.

CMV: Different outcomes do not imply discrimination

I found out the other day about Disparate Impact in the United States and was kind of concerned. [Here](https://www.investopedia.com/disparate-impact-5114526) defines disparate impact as: \>Disparate impact refers to the result of the application of a standard, requirement, test or other screening tool used for selection that—though appearing neutral—has an adverse effect on individuals who belong to a legally protected class. Which basically means “If the outcome of a law looks racist/sexist/ageist/etc. then the law should be treated as if it is racist/sexist/ageist/etc. regardless of if there was any discriminatory intent.” At some level, I agree, you should focus on policies that actually help people to succeed, not just on policies that claim to help people succeed, and I agree with it insofar as I agree that you should try to have effective policies that make a difference. However, the idea of disparate impact (and a lot of current political discussions) seems to be premised on two ideas I disagree with. 1. In the absence of discrimination, different groups/people would have identical outcomes 2. If there are different outcomes between groups, it must be due to discrimination. (You could argue that disparate impact is saying we don’t care if it’s discrimination or not, but I’ll respond to that later.) Just to be clear, (and because a lot of debate is, I think, from not agreeing on definitions) I’m using the following definition of discrimination: \>The unjust or prejudicial treatment of different categories of people, especially on the grounds of ethnicity, age, sex, or disability. For instance, denying someone a job because they’re male is discrimination, because it’s unjust and prejudicial. Denying someone a job because they aren’t as qualified as the other applicants, regardless of their identities, is just and fair. If 9 unqualified men apply for a job, and one qualified female applies, picking the female isn’t discrimination, even if the hiring manager happens to be sexist against men. Now, in response to 1. I think it’s just absurd. Cultures and cultural values, families and family values, goals in life, social skills, and inborn ability seem to have a much larger impact in an individual’s success or failure than discrimination, especially in a day and age when racism/sexism/etc. are illegal in many ways. And yes, discrimination may have influenced some of these things, but arguing that present or past discrimination is a significant causal force in every significant aspect of a person’s life seems like a really, really big claim. Additionally, a world history of groups that never interacted with each other having very different outcomes clearly shows that other aspects impact success than one group discriminating against each other. As an example: If you pick a random white person in the US, chances are 7.3% that they are in poverty. If you do the same with a random black person, chances are 18.8% that they are in poverty ([source](https://www.census.gov/library/stories/2020/09/poverty-rates-for-blacks-and-hispanics-reached-historic-lows-in-2019.html)). If you pick a different characteristic, though, you see even bigger differences than by race ([source](https://www.pewresearch.org/social-trends/2015/12/17/parenting-in-america/)): \>In 2014, 31% of children living in single-parent households were living below the poverty line, as were 21% of children living with two cohabiting parents. By contrast, only one-in-ten children living with two married parents were in this circumstance. In fact, more than half (57%) of those living with married parents were in households with incomes at least 200% above the poverty line, compared with just 21% of those living in single-parent households. So if you picked a random child in a single parent household, there is a 31% chance that they are in poverty. If you picked a random child in a two-parent household, there’s about a 10% chance they’re in poverty. If you had to pick a statistic to tell you if someone was in poverty, knowing if they’re in a single parent home or not is more reliable for prediction that than knowing their race. What I’m trying to get at is not the many issues of single parent families, but the fact that that there are many non-discriminatory things that contribute to inequality in the US. (If you’re interested in the interaction of the two, or how two-parent families affect black poverty, [this](https://www.aei.org/articles/the-power-of-the-two-parent-home-is-not-a-myth/) is an interesting article about that, though it’s not directly related to this issue) In response to 2. I think most people agree that this isn’t true, but that’s what I’m here to find out. For instance: A quick look at [the Wikipedia page on ethnic groups in the US by household income](https://en.wikipedia.org/wiki/List_of_ethnic_groups_in_the_United_States_by_household_income) shows that median income for Indian Americans is almost twice that of White Americans. Does this mean that White Americans discriminate for Indian Americans twice as much as themselves (however you quantify discrimination)? Or that Indian Americans discriminate against White Americans? Should we have protests against “Indian Power”? Or (as I think is more likely) that there are a host of factors involved in income, and Indian Americans tend to have more of those factors more of the time than White Americans. Even if, by chance, the overwhelming reason is discrimination, saying that there are different outcomes for two different groups isn’t enough to prove the existence or prevalence of that discrimination. You need more than a correlation to prove causation. Another data point I found interesting is this quote from [this study](http://www.equality-of-opportunity.org/assets/documents/race_summary.pdf), under the heading “The black-white income gap \[in America\] is entirely driven by differences in men’s, not women’s, outcomes.” \>Among those who grow up in families with comparable incomes, black men grow up to earn substantially less than the white men. In contrast, black women earn slightly *more* than white women conditional on parent income. Moreover, there is little or no gap in wage rates or hours of work between black and white women. Does discrimination only exist against black men, and not black women? Or are there other significant factors (besides discrimination, if that is a significant factor at all) that affect outcomes? Now, a note on what I’m not saying: I’m not saying that there isn’t discrimination against all sorts of identities and that this discrimination doesn’t have real consequences on outcomes, just that seeing different outcomes isn’t enough to prove that discrimination exists. I’m not saying that policies that disparately affect different groups are necessarily good, just that they aren’t inherently discriminatory. Now, I imagine some people will say “It doesn’t matter if it shows discrimination or not, the fact that the outcomes are uneven are enough to make them bad.” To which I sort of agree, sort of disagree. That’s not the main opinion I’m stating here, but I think it’s worth addressing within the framework of my opinion: I hope I’ve established already that equality of outcome is not a self-evident good. Some people want to live simple lives, or prioritize family above work, and so their goals in life may lead them to choose less remunerative professions or turn down promotions. Some people want more material goods, so a higher income is exactly what they want in life, even if it comes at the expense of other things like family or spiritual things. You wouldn’t expect these people to have the same outcomes in life as measured by financial numbers, and that’s okay. They’re both pursuing their own goals and not hurting other people by doing it, I say let them do things their own way. Now, if you have a policy designed to help people, and it helps people of some groups more than others, I think that’s something worth looking at. However, assuming it’s discrimination, or assuming it’s automatically bad and should be scrapped, isn’t helpful. It may be that the groups have different cultural norms, so that result would be expected, and nothing is wrong with the policy. It may be that the groups have different needs. If the issue is that group X needs A and group Y needs B, and the policy is providing A, then you don’t need to scrap the policy. You need to add another policy that provides B (which policy would have the opposite disparities). The policy isn’t discrimination because it’s providing A justly and without prejudice to everyone, that’s just not what everyone needs. If there is actual discrimination, you should address that. In short: look at what’s actually causing the disparity, then address that. I think my opinion on this could be summed up by a quote by a guy about a disparate impact decision by the supreme court: \> "our members are strong advocates for fair lending and enforcement of the Fair Housing Act. Disparate Impact theory, however, is not the right tool to achieve fairness and prevent discrimination in lending, This approach can have unintended consequences, such as causing financial institutions to shrink their operations rather than risk litigation, hurting the very groups it is intended to help." Anyways, my main point, and the main thing I’m looking to get other viewpoints on, is the falsity of the related ideas that 1. Without discrimination, people would have the same outcomes, and 2. If there are disparities among groups, it must be due to discrimination. Note: I know I used a lot of data, but I’m not using all the data to say “I’m right, you’re wrong”, I just think not enough people do their research and use real data in arguments, and I’m trying to be the change in that. I’m open to new perspectives and ways of looking at this issue, I just don’t like stating my position using unsubstantiated generalities. Edit: I'm going to bed now, thanks for all the great and helpful responses, especially in helping me understand Disparate Impact Theory and it's implementation in law. I'll respond to more of the comments tomorrow.

How do you feel about the studies done on black children that were adopted into Asian families, suddenly losing their disadvantages and being statistically similar to other classes despite the historic thoughts that they were naturally predisposed to a lower economic outcome?

ELI5: Phi, or the Golden Ratio - Why is it so prolific? What about the number makes it so useful? And why do we observe it so often?

I know that Phi is the approximate number you get if you divide each term of the fibonacci sequence by the previous one, and I know that the fibonacci sequence as well as the golden ratio can be observed in living organisms, music, architecture, aesthetics and mathematics. But why?

There is a reason it applies in some biological organisms (eg. It allows for more sunlight when leaves on a stem are arranged in this manner), but the idea that this ratio is especially prevalent, or meaningful, really isn't true. Of course, you can see it everywhere - if you are looking for it, you can find it (particularly if you're not too concerned about the exactness of the ratio)

[ATLA] Since Sozin and Roku were born on the same day, what would have happened if Sozin had been the Avatar instead?

Would he still start the War? Would it even start sooner? Would he even be allowed to leave for the customary 12-year Avatar training?

The influence of the Avatar's reincarnated spirit, plus Raava being the spirit of light, means that all Avatars are compelled to be helpful and kind in pursuit of balance. (note that being kind doesn't always mean being nice to everyone. Kyoshi was a major example of that) Their world-travels and years of training means that they connect with people all around the world, and strip away any prejudices they might have had in their young lives. Avatar Sozin would have ended up almost exactly like Roku, though maybe a little more heavy-handed in his approach to things, much like Kyoshi had been. If Sozin was still born the heir of the Fire Nation on top of being Avatar, he would have relinquished his throne in favor of a sibling or close relative. Because being the Avatar is far more important than the leader of a single nation. And the sages/white lotus/other organizations would have impressed upon him that fact. We have no idea what Sozin's family was like, so they still might have had the same processes that Firelord Sozin had, and perhaps still started the war. It wasn't until after Sozin took the throne that he instituted many reforms that transformed the Fire Nation into its most well-known incarnation. Before that, many people in his nation were highly spiritual and would not have balked against the advice of the sages.

ELI5: How does a queen ant come to be?

From what I understand, queen ants are usually much larger than other ants in their colonies and they pretty much just sit there and wait for others to bring them food. However what I don't understand is how does an ant become a queen ant? Are some ants just born much bigger than others and they automatically become queen ants? If so, why are those certain ants born much bigger than others? Or are queen ants born normal and somehow become larger than others during their lifetime and then become queen ants? It's a massive mystery to me! Also, I guess same question applies to other species that has similar things to queen ants, like bees, etc. Please shed some light to me on this! :)

It varies widely by species of ants, but most feed a few larva some special jelly and those larva will grow to become queen. Sometimes they'll make too many queens and the new queens have to fight to the death. Some ants will "promote" one sterile female, usually decided by fighting, into their new queen. In some species, the queen makes the decision whether to make another queen or not. Some ants don't have queens. Some Ants have lots of queens. Ants are interesting.

ELI5:. How are we able to learn behavioral traits of species never documented while alive? How are we so certain about dinosaur knowledge when it's based solely on fossils?

That question is similar to, "how is a forensic team investigating a crime able to know what happened if they never saw it?" They find evidence that was left behind that they can peice together to form a complete picture of what happened. Paleontologists do the same thing but with extinct animals. They use fossile records which can't be understated in usefulness. Some fossils are actually completely preserved in such a way that you can take it apart layer by layer and "disect" an ancient animal. You can see the remnants of the food they ate, the size and shape of internal organs, etc etc and in doing so use logical reasoning to figure out how those adaptations would have been used. Enviormental evidence helps too. A creature that builds a whole lot of nest in the same general area is most likely to be a group/pack/herd animal, for example. You also have the standard rules of evolution to help give you ideas as well. An animal that sticks out like a sore thumb or has an extreme adaptation is a clue that they specialize in some skill or trait because specializations are an evolutionary risk. (You *better* excel at it if you specialize or you've got nothing to fall back on.) Now, are they wrong sometimes? Definitely. Sometimes a hypothesis can look probable until someone finds evidence that conflicts with the idea. We saw dinosaurs as more reptilian for a long time, until people started find fossils that included examples of those dinos having feathers and other features that put them more inline with modern birds. Its a game of trial and error. The more evidence you can find, the more clear the picture can become.

Eli5: Why do muscles work? Like how does a blob of meat let you be able to move your bones and more

Muscles are basically bundles of fibers that can contract. A muscle fiber is a long chain of comb like structures that fit into each other, like when you interlock the fingers of both your hands. When you apply electricity to these fibers, the comb structures slide into each other, so the fiber as a whole gets shorter, and the muscle contracts. This is also why often people who get electrocuted can't just let go, their muscles are overloaded with electricity and they cramp up. The only way a muscle can 'un contract' is when another muscle pulls it in the other direction. So muscles come in pairs, one for each direction. The typical 'wiry' structure of meat is these muscle fibers.

What makes kosher dill pickles sour if they explicitly do not have added vinegar?

Traditional pickles are made by bacterial fermentation of natural sugars to produce organic acids such as the acetic acid of vinegar. The low pH of the resulting pickles acts as a preservative to prevent further spoilage. Many modern 'pickles' are simply fruit or vegetables soaked in vinegar and as such are not authentically pickled.

ELI5: Why can’t we build factories to just crank out tons of solar panels?

Maybe I’ve been playing too much factorio, but if the main ingredient is silicon it seems like we should be easily able to turn out TW worth of solar panels every year.

In the real world there is more than just making sure there are enough belts and trains. Each process takes time, space, and capital to produce. Mining the silicon, smelting, crystalizing into wafers, forming it into panels, coating them to reduce reflection, and wiring them all take steps and labor. Eventually there will be a bottleneck. Theoretically, it's possible to do crazy things with manufacturing. It's been seen in war time economies like during WWII where factories standardized designs, setup their tools to make specific products as fast as possible, and focused all efforts into making ships, planes, rifles, etc. So if a powerful nation just really wanted to absolutely print them, and had the political will to point a bunch of resources at the problem it's technically possible. China often will "direct" its economy to produce things it wants. Command economies have their benefits and drawbacks which is an entire other economic discussion. It's not perfect though, like during WWII when factories retooled to make war materials, consumer good production fell and quality of life suffered, or if the central power makes an inefficient decision you end up producing a bunch of products that simply aren't needed. Plus factorio has the benefit of centralized command to vertically integrate the entire process. Factorio, not enough red science? Well just work on that copper production. You're in charge of it, you can work that problem. Real world, not enough circuit boards? Well... unless you make your own factory then you're kind of just waiting like everyone else. And making a new factory cost money and expertise. Not enough aluminum in real life? Well unless the solar company owns an aluminum mine, the rail company to transport the ore, and the smelter, they can't really do much besides ask nicely.

ELI5: Why does a sunburn not hurt for several hours after actually being in the sun too long?

Worked out in the yard yesterday in the blistering heat and got a sunburn on my neck. When I came in I knew I must have burned my neck but figured it would take a few hours to know if it was going to hurt or not, curious why the pain comes so many hours after the "damage"?

As your body's response, capillaries open up, allowing more blood to the affected area. This aids in the healing process but also makes the area feel warmer and more tender. However, the response isn't immediate, taking the noticeable few hours before the inflammation sets in.

ELI5: Why does dehydration make you think you're hungry, when in reality you need more water?

Pure liquid water is not the only source of hydration, fruits and vegetables can also be sources. During evolutionary history there were plenty of times where the liquid stuff was not available but food was still available. Increasing hunger can thus encourage getting other forms of water.

ELI5: Why does the U.S. have a debt ceiling if it just gets raised every few months? Isn't it redundant?

Before 1917 Congress specified the details of financing in every spending bill. A bill authorizing the Navy to spend $10 million on new ships would also specify the term and interest rate of the bonds that would be sold to raise the money. In 1917, Congress passed a bill that authorized the Treasury department to issue bonds as needed to fund the spending authorized by Congress. This bill included a limit on how much debt the Treasury department could issue. A practice that is still followed almost 100 years later. It is redundant in that Congress already controls spending via legislation. If our nation actually hits the debt ceiling, it would force a default on our obligations and most likely create an economic crisis. In a rational world, the debt ceiling would be eliminated.

Eli5. Cold welding. Im a highschool student and ive got welding experience but i just don’t understand how cold welding works like in space and even on earth. What exactly constitutes a cold weld and how is it achieved? (Unintentionally)

Metal atoms really like to stick to each other. That's why metals are both flexible and strong. However, when metal atoms touch oxygen or water, they react easily to form an oxide. The surface of metal exposed to air is coated with the oxide which slows down metal atoms inside from reacting. Rust is one example of iron oxide. Cold welding occurs in an environment without anything in the air for the metal to react and form an oxide. Space is one such environment. When bare metal atoms touch other atoms in a cold weld, they stick together much like two water droplets fusing into one. For metal the cold weld causes two solids to combine into one larger one.

CMV: If gay and interracial marriage is legal in a state, then polygamous marriage should also be legal in that state.

A few things to note before a start: 1. I'm not arguing to the contrary against gay marriage. I am for gay marriage as I am for polygamous marriages. 2. I'm not arguing for forced marriage or arranged marriages where several women are forced to marry a single man, like in various religious sects, but the concept of a marriage containing multiple people as a whole. 3. I am as much for polyandrous marriages as I am for polygynous marriages. (i.e. women can have multiple husbands in addition to men having multiple wives. 4. Willing to discuss this *legally* and *ethically* in seperate spheres, but let's try not and mix the two together too much, unless absolutely necessary. It is assumed that gay marriage is both legal and ethical for the purpose of this discussion. If you believe gay marriage should be illegal or is unethical, then those arguments have merit towards polygamous marriage as well. Alrighty, now onto my main points. 1. Polyamarous people deserve the same right to equality, to marry who they love, just like homosexuals, and heterosexuals. Polyamarous relationships are no less moral than homosexual relationships, and relationships between consenting adults should be able to be consummated in marriage. 2. Marriage was not made legal by a popular vote in many places. The only country to legalize it via a popular vote was Ireland a week or so ago, everywhere else had it decided by judges or representatives. In the US, interracial marriage and gay marriage has been ruled as legal by courts, not voted in. Public opinion towards polygamous marriage is irrelevant. 3. When it comes to raising children, one can assume that since having a single parent results in worse-off children, then having a higher amount of parental figures and providers would make for a similar, if not better child-rearing than having one parent, two parents, or two parents of the same sex (all of which are legal). [Source] (http://archive.news-leader.com/article/20121125/NEWS01/311250054/single-parents-Ozarks-poverty) [Source 2](http://en.wikipedia.org/wiki/Full_House) 4. When it comes to insurance, legal proceedings, etc. everything can be easily adjusted to treating additional spouses as additional dependents (as where such institutions are adjusted for additional children). Yes, it is true that the current system does not allow for it, but it can be adjusted. When it comes to division of property, divorce, etc. things will simply be divided by the amount of people participating in the marriage, i.e. if there are three people, everything gets split 33%, or if the other two remain married, it gets split 66%. Prenuptual agreements can take care of anything that may be complicated by this if spouses have different intentions for how things are split. There will be a cap where insurance coverage/tax benefits end, i.e. if you have more than 7 children you stop receiving benefits for any more. For taxes and insurance, children are treated similarly to spouses, and additional spouses shouldn't complicate things out of reason. The specifics as to what the cap will be, how things get split, life and death decisions, etc. can be hammered out by individual states and individual people participating in a marriage, just like in other marriages. 5. Sham marriages containing two people that don't love each other, of the same or different sex are currently legal. *Chuck and Larry* marriages are currently possible, the only difference in allowing polygamous marriages would be to not allow odd numbers of people to participate in such marriages, rather than being in pairs. The difference here is insignificant. 6. The idea that polyamarous people are treated "equal" because *everyone* is only allowed to marry one spouse is the same type of "equality" where *everyone* is only allowed to marry within their race or sex. This is nonsensical. Everyone being held to the same standard of law does not work when people love people outside of what is socially accepted. 7. Polyamarous relationships aren't any less stable than homosexual relationships or heterosexual relationships. Even if they were, it shouldn't have any weight, as interracial relationships are much less stable than intraracial relationships. To argue that polygamous marriage shouldn't be allowed because of a instability in relationships is also to argue against interracial marriage. _____ > *Hello, users of CMV! This is a footnote from your moderators. We'd just like to remind you of a couple of things. Firstly, please remember to* ***[read through our rules](http://www.reddit.com/r/changemyview/wiki/rules)***. *If you see a comment that has broken one, it is more effective to report it than downvote it. Speaking of which,* ***[downvotes don't change views](http://www.reddit.com/r/changemyview/wiki/guidelines#wiki_upvoting.2Fdownvoting)****! 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>When it comes to raising children, one can assume that having a higher amount of parental figures and providers would make for a similar, if not better child-rearing than having one parent, two parents, or two parents of the same sex (all of which are legal). Source When your source is the TV show full house, you don't have a source.

ELI5: When the U.S. Government says "You can't sell pot" the individual States can decide "Oh yes we can!", but when the Feds say "You must allow gay marriage" why aren't the States aren't allowed to say "No!"

I'm pro gay marriage by the way, congratulations everyone!!

So there are two things at play here. Federal laws superiority over state law, and the government utilizing its ability to prioritize where it spends its limited resources. So when the federal government says possession and sale of pot is illegal. It absolutely is illegal and if you were arrested for it, even in a state that legalized it, you would absolutely be found guilty and punished under federal law. But the thing is the only way that happens is if someone actually arrests you, and since the states decided they weren't going to participate in enforcing that particular federal law the federal government hasn't really bothered to put in the effort to do it themselves. Just because something is illegal on the federal level doesn't mean state officials must arrest people for it. ~~They're allowed to~~ (Edit: It looks like they're not normally allowed to, thanks for the correction!), but it's not required. On the other hand we have gay marriage. States already perform marriage, they're in the marrying people game. The supreme court effectively said you're not allowed to refuse marriages to people who want to marry someone just because of their sex. The difference here is that if the states don't enforce federal pot laws, there aren't any victims who can sue. Who is harmed by not being arrested? But the states **must** not discriminate in marriage anymore, if they do individuals would be able to sue and the courts would compel marriage officials to perform the act, or send them to jail. The main bit is, no one is a victim when states refuse to enforce federal drug laws. But there would be victims if states refused to follow the Supreme court ruling on same-sex marriages.

How would you fund consumers in a post-jobs world?

Imagine a future where robots and AI have surpassed humans in their ability to perform jobs. They're stronger, more precise, more creative, more empathetic, more flexible - name a skill, and the robot beats the human at it. Let's dodge for the moment the hairy question of whether owning a robot like that constitutes slavery (assume ownership works like today, humans and companies can own robots and AIs). Assume also that robots are long-lasting and power efficient so the marginal cost of running them is minuscule. Long story short, the market value of labor drops to near zero, as robot labor outperforms human labor on every metric (except for branding/excentricism, e.g. to show off your human butler). Historically, labor displaced by automation has found new jobs, that they could still perform better than machines - but imagine in our scenario, that we've finally run out of those, the robots now beat us at everything, there's no job we can come up with where the robot isn't already superior. How do you maintain the purchasing power of consumers in a scenario like that, in order to maintain a market economy? Most consumers get their money by selling their labor, but the market value of that has just tanked. Sure, goods are cheaper as well now that they are produced, transported and sold by robots (production costs are now basically energy + raw material costs), but as long as they are just cheap, rather than free, then that's no use to the majority of people who are now unemployable. If your answer is Universal Basic Income, then how do you fund it? Most of taxation currently comes from taxing labor, and in our scenario that has now mostly disappeared. We might increase VAT, but can that ever be enough to fund the "stipend" from which the VAT will be drawn when spent? (that doesn't seem to add up, some of the money flowing to the corporation would need to eventually make it's way back into the hands of a consumer, like it currently does via salaries). Since all these corporations that own all these robots are now massively profitable without employing anyone, maybe we can tax all this economic activity that is still going on there? But Amazon and others have shown that you can basically defer corporate taxation indefinitely by continuously reinvesting all your surplus cash and thus never actually making a profit. Do we start taxing them on revenue instead? Or do we tax the owners of the corporations? We've recently learned that stock owners can basically defer realization on their stock gains indefinitely too, by taking out loans instead of cashing in. So do we tax them on gains annually whether they sell or not? Or do we tax them on wealth instead of income? Could some combination of these actually be enough to fund a UBI in scenario like that? If yes, how would it affect the economy if all these things that are currently taxed relatively little compared to labor were taxed a lot more? If no, do we need to be thinking in some completely other direction, to still make a market economy work in a scenario like that? Edit 1: by using the phrase "market value" I seem to have implied that robots are already completely deployed everywhere in the market - I didn't mean to imply that (sorry, I'm an engineer, not an economist). I'm asking about the scenario where they exist, but might not have been made widely available yet (i.e. I don't want to assume everyone has a robot, because IMO that would be jumping the gun to assume that will come to pass). Edit 2: to clarify, minuscule power draw is compared to a human. Assume servos, batteries, cpus and such with a power draw similar to what we know today, not magic perpetual motion machines. So the cost of running these is small (especially compared to a human) but not non-trivial (at least no more trivial than the running of other well-made machines).

>How do you maintain the purchasing power of consumers in a scenario like that, in order to maintain a market economy? Purchasing power? You are describing post scarcity! If what you are saying is true then these machines can be created at no cost and run at no cost and perform duties better and more energy efficient than any human ever could. That is post scarcity and the only thing we would need is figure out how to distribute land and trade seasonal perishable foods.

ELI5: Holocaust deniers, how and why do they deny it ?

For some, the rationalization is that they see some sinister Jewish shadow conspiracy to control the world, and believe that all claims related to the Holocaust are falsified in order to further the aims of that Jewish conspiracy. The more "not stupid" version, is simply people who believe that the reports associated with the Holocaust, particularly the numbers of the slain, are inaccurate or exaggerated, or that reports of outright mass-execution and actual extermination were overblown. Some just don't want to or can't accept that such events happened, because it says very uncomfortable things about what humans will do or can be coerced to do under the right circumstances. Sadly, as horrible as it was, the Holocaust's reality was fairly well-documented.

Presenting at a Conference for the 1st time...

So, I'll be presenting a paper at a conference and as time gets closer, I'm dreading it more and more. I get incredibly anxious with public speaking, and I'm pretty sure my anxiety is not only noticeable, but also distracting. I swear that sometimes it probably sounds like I'm not even speaking English. I haven't actually attended any conferences before, so I don't know how they play out. But, I assume that most participants will present their work in the same manner that they would present a lecture. I don't think I'm capable of doing that though, so I'm wondering if it's at all common (or at least acceptable) for a presenter to just read their paper verbatim? Also, there's probably not anything to do to ease my anxiety other than to just try and get over it... but if anyone has some tips that they think would be useful, I would appreciate hearing them.

Where is your lab/workgroup/advisor in all of this? You should definitely consider doing a practice talk in front of your lab group or close friends so you can get comments for improvement (or positive feed back!) and maybe a few questions that you might expect from the audience. Write a script if you need to, practice the talk until you're comfortable, and push through when the time comes. I have a colleague who is terrified of public speaking. She always sounds like she's on the verge of tears during her talks. No one in the audience makes fun of her, gives her a hard time, boos her off the stage, or anything that might worry you. Despite her poor delivery, she can easily and competently talk about her work in a one-on-one situation. If someone is interested in your work, they'll approach you in that way.

[STAR WARS] Why was everyone in the senate so onboard with Palpatine creating the Galactic Empire?

Increased security measures. Like a standing military that was centralized instead of relying on local militias. Trade practices standardized and preferential treatment of the core worlds. Relaxed restrictions on exploiting worlds in the mid and outer rim. Streamlining the process of government. It took years of planning but palpatine made the Senate feel like they were suffering under republic rule and that he was the one to get things done instead of months of debating and dealing to find solutions. The republic had just seen a simple trade dispute turn into a massive rebellion that was put down thanks only to palpatine bringing the grand army out of hiding and waging a war against the separatists that publicly was credited to palpatine not the jedi. And it took nearly 19 years before the senate was losing power. All they saw at the time was removing the need to have an elected leader of the Senate and having an authority that could come in and decide any issues without need for a Senate debate if it was needing a speedy response.

Is there logic, and has any theory been written around the idea that God, in the context of religion is a scapegoat or rather an excuse for the shortcomings of human behavior?

When someone says, for example when a natural disaster occurs and people die that, "God has a plan," rather than, "We should have done a better job building that building or evacuating that population, and we knew this was vulnerable but we didn't want to spend the money needed to do it right." By convincing people that God did this for a reason we can't possibly understand, we place the blame elsewhere for what could have been preventable.

In *The Essence of Christianity*, Ludwig Feuerbach advanced the view that God is an outward projection of a human's inward nature. > God is for man the commonplace book where he registers his highest feelings and thoughts, the genealogical album into which he enters the names of the things most dear and sacred to him. (pg. 66 of the Barnes & Noble version) So, in your example, God acts as the projection of man's own ideal of omniscience which man self-consciously recognizes is a limitation for man in general. Feuerbach also discusses how an individual can project their individual limitations to be limitations of man as a species, which ties into the kind of thought process you're thinking of, i.e. "We didn't anticipate this, and therefore no human could have anticipated this - only God could."

If water conservation is so vital to mammals, why do we pee? Why not transfer toxins into stool and recycle the water? Are there any animals that have evolved to do this?

Bizarre thought I had upon waking up that is now bothering me a great deal.

Safely excreting waste tends to be a balancing act between water and energy. Land animals in non-desert climates tend to urinate in the sense you are familiar with. However, animals in climates in which water is very precious or those which can't carry a lot of water due to weight (birds) use a different method of getting rid of waste. A large part of what we're getting rid of in urine is nitrogen waste so that we don't build up ammonia. We get rid of nitrogen by making a compound called urea in a cycle called the urea cycle. It uses some energy to make, and takes a lot of water to get rid of. In contrast, birds, reptiles, and some desert mammals get rid of nitrogen by making a different compound called uric acid. This takes more energy, but can be excreted as a paste with only a little water in it (this is the white part of bird poop). It's a balancing act as to whether the water or the energy is generally more important, and so different species have gone different ways.

ELI5: How did primitive humans, with a top speed of 28 mph, hunt large mammals like deer, bears, wolves, etc, that can reach speeds of near 35 - 40 mph?

1. Tools: Primitive humans could sharpen a stick to make a throwing spear, and build sharp points from things like flint, wounding or killing an animal from a distance. Also: Slings, throwing rocks, building traps, and fire. There is a place in Alberta, Canada called (charmingly) "head smashed in buffalo jump" which is where ancient native americans would chase herds of buffalo off a cliff, where they would fall to their deaths. Then the natives could just walk around to the base and collect meat, hides, and all the other resources at their leisure. 2. Endurance: No other animal on earth can run as far a human. World champion race horses have to rest for days to recover from a single race. Humans can routinely run marathons, 42km, with training. There are several cultures that still exist that use endurance chases to corral prey animals into traps or kill zones. 3. Stealth: It's hard to imagine for a "civilized" person, but humans can be extremely stealthy in the wild with proper training. Getting close to an animal allows you to kill it before it has a chance to run. 4. Teamwork: Just as a pack of wolves or lions can bring down much larger prey, ancient humans could co-ordinate better than almost any other animal using perhaps our best tool: language. Surrounding an animal, tiring it out, and only when it's weak going for a kill allowed ancient peoples to bring down huge animals, like mammoths. I would like to add that hunting predators like bears and wolves is rare, because often they don't run AWAY but fight back. Also generally the meat of predators isn't great to eat anyways.

Is it wrong to take a walk in the woods, since it's almost inevitable that I will step on an insect?

I'm aware that the question is a little ridiculous, but it's been stuck in my head for quite some time, I don't know the answer, and it's draining me. I enjoy taking a hike in the woods, but there's almost a guarantee that I will trample at least one insect to death unintentionally. Should I therefore not take a walk in the woods? Should I feel bad?

Jeffrey Lockwood, an Entomologist, argued for the following "minimum ethic" in his paper *The Moral Standing of Insects and the Ethics of Extinction*: >We ought to refrain from actions which may be reasonably expected to kill or cause nontrivial pain in insects when avoiding these actions has no, or only trivial, costs to our own welfare. By this definition, hiking may or may not be justifiable depending on how important it is to one's "welfare". Presumably, the justifiability of this action also increases if one acts to avoid killing insects while hiking, such as watching one's steps more carefully.

ELI5 - Why are animals much more stronger proportionally to humans.. eg. How are horses capable of running for hours on end and oxen can pull cars like it's nothing

How come bears, tigers, even apes are naturally so powerful... And why are humans so weak in comparison

Different species were naturally selected for different things. Tigers and lions are incredibly powerful, which is great for hunting, but not very active. Humans had natural selection two particular traits: endurance and intelligence. Unlike a lot of other animals that use speed or power in short, sudden bursts to hunt, humans are the marathon runners of the animal kingdom. Someone in good physical shape could chase prey for hours intermittently until their prey gave up from exhaustion. Intelligence, the other trait, allows humans to form long range weapons, such as bows and arrows or throwing spears to attack from afar. When combined, humans make incredibly effective hunters. Raw strength, while helpful, just isn't as important for humans to he effective in gathering food. In fact, lots of muscle mass burns extra calories that aren't strictly necessary and adds additional weight to the body that needs to be more lean for endurance.

ELI5: Finally need to settle the score, is it the washing machine or the dryer that shrinks my shirts?

Dryer, usually. Think about what happens in each machine, versus how you would do it by hand. When you wash clothes by hand, you put them in water with some laundry soap and swish them around a lot and then rinse the soap off. That is exactly what a washing machine does, so if washing stuff by hand doesn't shrink it, a washing machine probably won't. When you dry clothes by hand, you put them on a rack or clothesline and wait. When you dry them in a dryer, it heats them very hot and tumbles them around quickly for about an hour. The heat is usually what shrinks stuff, so if you put things on the very hot cycle in the washing machine, they still might shrink. But if you put clothes on the normal or gentle cycle in the washing machine and then hang them up to dry, they will almost definitelynot shrink.

What is the origin of spin, from the perspective of quantum field theory?

Spin arises directly from considering quantum mechanics with rotational symmetry, even without introducing field theory. In any quantum theory with a symmetry, you can arrange all states in irreducible projective unitary* representations of the mathematical group describing that symmetry. For rotations, these representations correspond to states which carry spin. Adding special relativity enlarges the symmetry group, introducing chirality and the fact that states carry a mass (and zero-mass particles have helicity instead of spin). These representations are naturally associated with/defined to be "particles." Nothing says that you *have* to have particles with a given spin. But our own universe does take advantage of the ability to have particles with nonzero spin. Relativistic quantum mechanics does end up leading you to introduce quantum fields and quantum field theory - you make all of the operators in your theory into operator-fields which transform in some (not necessarily unitary) representation of the Lorentz group. One usually matches fields with a certain representation with the particles which they create when acting on a state. But these are tools you use to describe spinfull particles, they're not really the "origin" of spin. \* Or anti-unitary, which usually concerns time-reversal symmetry.

If a person loses their dominant hand, will their other hand ever gain the dexterity of the lost limb?

On a related note, if somebody is born without the hand that would otherwise be dominant due to a birth defect, will their remaining hand be clumsier than normal? Does that question even make any sense? Thanks, experts!

this is an empirical question, not a theoretical one, because dexterity is defined empirically. and because of the limited number of people to which it applies, anecdotal evidence is appropriate. a friend of mine had his right arm badly injured in a car accident when he was a kid. so he had to start doing almost everything left-handed. a decade later, he was very proficient, but you could still clearly tell that he wasn't as dexterous (even as, say, an 8 year old using their natural hand). writing, typing, eating, you name it. of course practice makes you much better. but to me this is explicit evidence that one does not fully gain the dexterity of their original dominant hand. no amount of other people who might have gotten slightly better can disprove this empirical observation. edit: to the mods: unless you understand why it's inappropriate to use a fixed effect statistical analysis on data of this nature, you shouldn't be removing this comment for being anecdotal.

ELI5: What makes blood a different "type"?

What's the difference between blood in people that means we have different "types" and why are some incompatible?

Our blood contains antibodies and antigens. Different people have different antibodies/antigens. Antibodies attack antigens of the same type. Blood type O has no antigens and both A and B types of antibodies. Blood type A has antigen A and antibody B. Blood type B has antigen B and antibody A. Blood type AB has both antigens and neither antibodies. There is a final important antigen, known as D, which people are either positive for (they have it) or negative for (they don't have it). This means that someone whose blood type is A+ has antigens A and D, as well as antibody B.

Why do manufacturer to consumer direct business models often fail?

I work in an industry where manufacturers sell product to wholesale distributor at markup, then distributors sell to retailers, then retailers sell to consumers. The markup from wholesalers to retailers alone is 100%. Why don't manufacturers sell directly to consumers at a lower price, but higher profit?

Access to consumers directly requires a differentiating business model that most manufacturers don't have or want. Logistics and the ability to capitalize on choice is a speciality that many companies also don't want to focus on. They'd often rather focus on innovation and brand quality in their own space.

CMV: Either abortion is an act of homicide, or it is morally equivalent to contraception. There are no logical alternatives.

To clarify, I'm not arguing that human life begins either at conception or at birth. Rather, my argument is that, for any given abortion, either the fetus is already a human life (making the abortion an act of homicide), or it's not yet (making the abortion equivalent to contraception). If, for example, you take the position that abortion is equivalent to contraception up until the moment of fetal viability, after which it becomes homicide, I regard that as a perfectly consistent position (at least for the sake of this post). The one position I find illogical is the idea that, despite the fetus not being a human life (meaning abortion isn't homicide), abortion is still a tragedy, and we need to do everything we can to minimize the number of abortions, whether that's through sex ed, better access to contraception, affordable healthcare for children, etc. Granted, those kinds of policies may be good in and of themselves, but I'm speaking of them in reference to their alleged necessity in preventing abortion. There are only two reasons I can think of as to why someone would express this position. Either they're secretly pro-life but in denial, or they actually don't care about preventing abortion and just want the pro-life movement to shut up about the issue and focus on these other, seemingly more important issues. I just don't understand why anyone would sincerely hold that position. If abortion isn't tragic due to the loss of human life, then what's tragic about it? Answer that question sufficiently, and you will have changed my view. Edit: To clarify, when I say "homicide", I'm referring to a deliberate action that causes another human being to die. [This is the definition Wikipedia uses](https://en.m.wikipedia.org/wiki/Homicide), and it's the one I intended. I've seen a few comments effectively arguing that abortion is a justifiable homicide akin to euthanasia, which is not what my argument is about. Edit 2: I've noticed two basic lines of argument that were deserving of deltas, and I'll mention them here so I don't have to see them over and over again. Argument 1: Abortion can be viewed as a cover-up of sexual immorality. Destroying the evidence of a crime is typically a crime in and of itself. If abortion is terminating a pregnancy and pregnancy is evidence of sexual immorality, then abortion is the destruction of evidence of immorality and is therefore immoral as well. Unfortunately, this view is often coupled with misogyny. Men are expected to be promiscuous, and women are expected to be chaste. If a sexual encounter was immoral for both partners, then a man who gets a woman pregnant would be culpable for abortion as well, since he's an accomplice. But if the sexual encounter was only immoral for the woman, only she would be culpable. This is one reason why women get much more blame for abortion than men. However, it also explains why some people make an exception in the case of rape. If she didn't consent to sex, then she's not destroying evidence of any immorality on her part. Argument 2: Abortion can be viewed as some sort of semi-homicide. Becoming a human is a process of development, and there's no "magical moment" when a fetus becomes a human being. As such, the fetus doesn't have the same right to life that a born human child has, but it still has more of a right to life than a clump of sperm cells. So, even though abortion would involve killing an organism with human DNA, it doesn't really fit nicely into the homicide/not homicide dichotomy. This explains why some people oppose abortion if it's done purely for convenience, but they'll tolerate it if the pregnancy poses an unexpectedly large burden on the mother.

What about the possibility that life is less of a binary that snaps at a particular point, and more of a continuum? Or what about the argument that one can be unsure of where life begins, exactly, and thus choosing a point (based on whatever- some might argue arbitrary, some might say meaningful) at which moral sanction and/or legality should be revoked? As to you last question- abortion can be tragic for reasons that have nothing to do with a loss of human life.

In Layman's terms, how do the new RTX graphics cards calculate the path of light rays?

The maths behind raytracing isn't too complex. You work out where a beam of light hits a surface, and then you work what direction it bounces to etc. The problem is that you have a *lot* of rays of light to deal with, and that gets computationally expensive. So what you do is you run the calculations in *parallel*. That is, instead of having one processor chip doing one ray at a time, you have several chips running one ray each at the same time, and that speeds things a up a lot. Now, this is where you have a choice. You can either use a small number of expensive but fast chips with lots of features, or you can use a large number of cheap but slower chips with minimal features. Which is better depends on a lot of things, but mostly on how complex your problem is, and how easy it is to split up your problem into small chunks. If the chips have to do a lot of communication with each after to solve the equations, then it's usually better to have a small number of fast chips. But if the chips can solve the equations independently of each other, then it's usually better to have a large number of cheap chips. Raytracing is one the best examples of the second type. The maths for the rays can all be done independently, and the equations are actually pretty simple. So what you want is a large number of cheap chips. *And that is what a graphics card is*. Your computer might have 2-16 expensive "CPU" processor chips, but a GPU (a graphics card) might have hundreds or thousands of cheap "GPU" processor chips. So, for these particular problems, the GPU solves them much much faster. Additionally, because people use GPUs for problems like raytracing so often, they can actually hard-code some of the maths onto the chip to make it extra fast. So if you're doing something like matrix multiplication, which involves several steps of additional and multiplication, you'd normally have to do each of those steps one at a time, sending the results back and forth each time, storing things in memory along the way etc. A GPU might have a special section dedicated to matrix multiplication, so you send in a chunk of data and it spits out the result extremely fast without having to go through the intermediate steps. But the key thing is that a GPU is a big pile of cheap processors, and that's often a lot faster than a small pile of expensive processors.

ELI5: Why do different species have different life spans? For example we live to a maximum length of years, yet a giant tortoise can live to like 170 years old? What determines this?

Genetic programming, basically. First, take all other causes of death - accident, predation, suicide, and so on - out of the picture so you're only dealing with creatures dying "of old age". What happens as most creatures age (there are some exceptions) is their cells eventually can only replicate so often and repair or replace components within their body so many times. Eventually more and more of those cells run out of times that they can duplicate and replace themselves. They die, the organ or body part their in dies or becomes critically damaged when enough cells within them die, and of course so does the organism. Different animals duplicate their cells at different rates, and there's a decent correlation between size of the creature and length of its natural lifespan. Mice grow much faster (and breed much faster) than men, and run through their cells' "max refresh count" a lot faster as a result. So they live a shorter life. Galapagos tortoises run their counter a lot slower, however, and so they can live a lot longer. It's also correlated to how fast the animal goes (hummingbirds live a lot fewer years than giant pandas), but not perfectly so.

ELI5: How the United States is operating as a nation while being trillions of dollars in debt

That is like asking how do you operate as a person if you have a mortgage? You can operate if you are in debt. Banks from all over the world have lent the US money. Should we ever default the world wide economic system will be fucked beyond belief.

The Nobel Prize in Chemistry this year was awarded for super-resolution fluorescence microscopy. How does it work?

Normally, in samples you see a diffuse spread of thousands or millions of fluorescent molecules. You cannot resolve these individually because the light coming from each of these particles is "fuzzy" and gets blurred out because of the fundamental nature of photons. This fuzziness arises from a limit called the diffraction limit. It turns out that you can localize fluorescent particles better than this limit, but you need to do some tricks. One way of seeing below this limit is to image the particles one at a time. If you want to see below this limit, you need a way of only imaging samples such that the particles you see are not so close together. It turns out that you can localize them individually much better than you can when they are all together, so you just need a way of randomly localizing them one at a time. One technique is called PALM (photo-activated localization microscopy). Another way is to use some exotic properties of fluorescent materials that arise because of photophysical properties. These are properties that arise from the way the electrons transitions in these materials. If you are careful about the way you image, you can excite a super-small portion of the material, smaller than the diffraction limit mentioned above. If you do this and sweep over the entire sample, you can get resolution better than the diffraction limit. This is very simplified way of describing it, but this technique is called STED (stimulated emission depletion microscopy). This technique is also similar in principle to something called "near field microscopy," where you only illuminate your sample with a tiny probe that is smaller than the wavelength of light you would ordinarily illuminate with. This probe is like a nanoscale flashlight. If you sweep this tiny probe over your sample, it will fluoresce only when your tiny probe is in a place where it can generate fluorescence. This is another trick to "beat" the diffraction limit. **Summary** A lot of this work has been slowly developed over the last 20 or more years. The diffraction limit remains a fundamental limit of light resolution, but it turns out that if you do the experiment with certain tricks in just the right way, you can get around some of the limitations it imposes. Basically these guys won the Nobel for these tricks.

My 12 yr old wants to know "what's the difference between hydrocarbons and carbohydrates?"

He said "it sounds like the difference between H2O and OH2 that it's just the same thing". I told him that it's the difference between gasoline and bread, but that's really a non answer.

Hydrocarbons are compounds that are composed only of hydrogens and carbons. Carbohydrates are compounds that are made up of Carbons, hydrogens AND oxygens. Carbohydrates usually have a specific formula as well where the number of Hydrogens are twice as much as number of oxygen. For example: CH4 is a hydrocarbon and C12H22O11 is a carbohydrate. TLDR: Hydrocarbons are C and H only. Carbohydrates have C,H and O with specific relationship between H and O

Diversity statements for faculty positions

I was wondering if anybody had any tips for writing those. While I am definitely in favor of diversity initiatives, I feel like writing about them can fall a bit flat, and worse yet, sound a bit white-saviory. I have gotten advice before to bring my own identity into the statement. I am a white woman of LGBTQ identity, but would like to leave that out of the statement if possible (feels weird to talk about this aspect of my identity in a job application, you never know who is reading). Anyways, if anybody has any advice, that would be really appreciated.

I think there's a few important points to make in those kinds of statement: * You recognize that you will be teaching a diverse student body. * You value that diversity and what it adds to scholarship * You had an experience with someone different than yourself * Students are unique individuals with intersectional identities, and individual challenges and goals. Being a good educator means addressing those individual challenges to meet those individual goals. * First generation college students will struggle, so your experiences apply to helping them I wouldn't make it a white-savior thing, or go on and on about privilege or how you're going to uplift people or whatever. The diversity statement is meant to show that you've at least thought about issues of diversity, not that you personally have the solution to every social inequity