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Why would sampling distribution tend to be normal distribution in large sample sizes even though the population distribution is not normal? I know that it happens but why does it happen? I am not very math heavy so i need an explanation in easy language

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Imagine a uniform distribution. Let's make it real simple, its just the numbers 1-6. Now think about picking two of these numbers at random to make a sample. Then, let's take the mean of that sample. Here are all the options: 1,2: mean = 1.5 1,3: mean = 2 1,4: mean = 2.5 1,5: mean = 3 1,6: mean = 3.5 2,3: mean = 2.5 2,4: mean = 3 2,5: mean = 3.5 2,6: mean = 4 3,4: mean = 3.5 3,5: mean = 4 3,6: mean = 4.5 4,5: mean = 4.5 4,6: mean = 5 5,6: mean = 5.5 Now lets line up all those means and see how common each are: 1.5, 2, 2.5, 2.5, 3,3, 3.5, 3.5,3.5, 4, 4, 4.5, 4.5,5,5.5 Or in terms of their counts: 1.5: 1 2: 1 2.5: 2 3: 2 3.5: 3 4: 2 4.5: 2 5: 1 5.5: 1 As you see, this already looks normal-ish, as you are more likely to end up with a mean of 3.5 than any other mean, and it is symmetric around this. Since this is the distribution you are pulling from when you pull random samples of size 2 from your population and take the mean, your sampling distribution will approach this.

ELI5: What is the difference between poison, venom, and toxin?

*Toxins* are substances which have a profound negative effect on the body, which may be produced by the body or from an outside source. *Poisons* are toxins which are ingested, and often are produced by plants. Potassium cyanide is such a poison. Lead and arsenic are examples of inorganic poisons (they have no carbon). *Venoms* are organic toxins which are injected, and usually are produced by animals.

Is Maths a branch of Logic or is Logic a branch of Maths? Why? What does it mean to be a "branch of" a discipline?

A branch of another discipline would mean everything contained in the branch is a subset of the parent discipline. This would be like calculus being a branch of mathematics since everything in calculus is math but math is more than just calculus. Neither math not logic is a branch of the other since both has a scope beyond what is tought in the other. Mathematical logic is a branch of both logic and math but Math has more topics beyond that like calculus and logic has more topics beyond that like logical theories in formal languages.

ELI5: Turbo in an Engine. And the difference between Turbo, Turbo-charger and super-charger and how these differ from just a regular old combustion engine.

First, understand that the mix gasoline and air combusts best in a fairly narrow range of ratios. So for a given amount of air, you have to have a proportional amount of fuel to make the engine work well. The more fuel-air mix you can burn, the more power the engine will produce. It's reasonably easy to get more fuel into an engine; the challenge therefore is to get more air in for the fuel to mix with. A turbocharger (aka turbo) is two turbines joined by a shaft. One turbine is the the exhaust stream of the engine, so that any time the engine is running, the exhaust spins the turbine. This turns the shaft, which turns the other turbine, which is in the intake. The turbine on the intake side pushes more air into the engine. Since there's more air, more fuel can also be added, and this makes more power. A supercharger has the same effect - it pushes more air into the engine, but it's driven by a belt rather than by the exhaust gasses. The belt turns a centrifugal impeller or a screw-type pump to do this. Again, more air means more fuel can be added, and the engine can make more power. With neither of these things, engines work fine for a lot of applications. The simple motion of the pistons creates a vacuum, which sucks in air pretty well; but again there's a limit to just how much air an engine can get this way - and therefore how much fuel can be burned.

ELI5: How do new allergies develop?

How do people start developing allergic reactions to things they weren't previously allergic to?

I was taught to think of the immune response like a police traffic stop. An unknown protein is driving along, and gets pulled over by a police officer because it "doesn't quite look right". Everything is fine and the protein is allowed to continue. The officer files a report that they did the stop and this is put on the police computer. That protein is seen again and when a police officer sees it, it sets off an alert because it had been stopped before. The police officer tries to stop it to see what is going on. The protein is allowed on its way, and another report is filed. Later on, the protein is seen again. A police officer sees it, and sees that there have been several stops made, so he gets quite twitchy and stops it with even more force. It is allowed on its way as it is doing nothing wrong, and another report is filed. The protein is seen again, there are huge red flags because of the amount of times it has been stopped and the level of force used when it has been stopped. an armed response unit is sent to stop it. Nothing amiss happened, so it is allowed on its way. The next time it is seen, an armed response team is deployed again based on past stops, it is surrounded and forceful entry is effected damaging nearby structures as the police raid where the protein is to see what is going on and why it has so many markers against it. ​ The protein itself is doing no damage, but the immune response is having the negative effect on the body systems. The immune response increases with each exposure, leading to more damage on the systems.

ELI5: Why do male athletes in sports like baseball, hockey, or football rarely debut before about age 20 and typically peak around age 25-27, but female tennis players can reach the top rungs of their sport at age 14/15 (Austin, Capriati, Hingis)?

You never see a 14-year-old male competing in competitive sports. Yes there was a 15-year-old baseball pitcher once, but he did very poorly. Typically superstars in these sports don't have even decent seasons until age 18 at the absolute earliest. However, women in tennis sometimes burst onto the scene as 14 or 15-year olds. Why? Is it their being female? Is it tennis?

Male athletic performance depends on muscular strength and power, which for most guys doesn't fully develop until their early 20s or even later. Female athletic performance isn't juiced by testosterone like male performance, and so those extra 5 years of the body maturing doesn't bring increased performance like it does for men. In fact, in some sports the widening of the hips and ongoing breast development may make it harder for 20 something women to compete, in general.

Can many small, quieter speakers produce sound equivalent to a single larger, louder speaker?

Say I have 200 phones playing a song, does the volume increase when coming from many sources?

Yes, due to a principle called constructive interference, the sound waves with matching and in phase frequencies will build on eachother, making the amplitude higher and the volume louder. Think of a crowd cheering in a stadium for a simple example. However, from an engineering point of view the sound would probably sound distorted unless you were listening in an open field, or the small speakers were very close together. This is because the holes you see in speakers are designed to 'spread' the sound out, and with multiple different speakers the waves could reach you at different times causing a very slightly dodgy sound (this may well be an insignificantly small error however)

I don't understand virtue ethics at all. Why is it considered an ethical theory on its own and not a supplementary psychological theory to consequentialism and deontology?

MacIntyre in After Virtue wants to illustrate virtue ethics by the example of a child playing chess. If it's just after the reward (e.g. a candy for winning), it will have an incentive to cheat. However, if it's genuinely interested in playing chess, it would only rob itself by cheating, instead of playing properly, learning from its mistakes and becoming actually good at the practice which is playing chess. But... once the child is very good at chess, shouldn't it be able to make rules and recommendations like "If your opponent does X, then doing Y is the optimal choice" or write a book about chess playing incorporating many strategies which would, if applied, make one as good as the child player or at least better than before? Heck, even the claim that there's cheating at all seems to imply that there are right and wrong things to do in chess and if I want to get good at it, I need to respect these rules and not cheat. But if that's the case for virtue ethics and I can only become virtuous (good at chess) by acting virtuously (respecting the rules of chess), then how do I know how to act to become virtuous in the first place (how do I learn the rules of chess? How do I know if I'm cheating or playing right?). It seems weird that people just accept it as a brute fact that virtuous people can't articulate the reasons why they do the things they do to non-virtuous people (do they? Are they?). Who makes the decision when someone is considered virtuous? What's the underlying principle? Why can't it be passed on to other non-virtuous people, so they can start acting morally without the trouble of trial-and-error a virtuous person seems to undergo? How does the person wanting to become virtuous even know that an act was not virtuous but vicious and that he shouldn't do it again? How is the dialogue of A saying "Torturing others for fun is not a thing a virtuous person would do." and B saying "But it totally is!" or C saying "There's no telos and thus no virtuous person insofar as it would be a person who has realized his telos" different from A' saying "Torturing others for fun is wrong!" and B' saying "But it's totally right!" or C saying "There's no wrongness!". How is it less arbitrary, so that MacIntyre can actually argue that it would solve the "culture of emotivism" which modern moral philosophy caused? I would get virtue ethics if it would simply state "By acting like an ethical principle is correct, I will internalize its tenets and my desires will be reshaped accordingly, so that eventually I'll actually desire what's morally right (= virtuous?)". It would be a simple psychological recommendation for people struggling to reconcile their desires with their moral intuitions. But virtue ethicists don't seem to view their theory as merely such an psychological supplement and tool for other ethical principles but as its own beast. So... what is it? Please no links to the SEP without further explanation. I've read the article. I've read Nussbaum's article. I still don't understand it. That's why I'm asking you.

>Who makes the decision when someone is considered virtuous? What's the underlying principle? This seems to be your underlying question here. For virtue ethics, it's based off of what Aristotle calls the 'function argument', which illustrates a key concept in virtue ethics: *telos*, a term for the end sought by an act/the end to which an act is directed/the meaning and goodness of the act. Teleology is an approach which considers the *telos* of things. If virtue is a disposition to act according to right reason, then Aristotle's function argument utilizes *telos* to determine what the 'right reason' is. He gives an example of a shipbuilder. The *telos* of shipbuilding is to build ships. So if you build a ship that sinks, you did not fulfill the *telos* of shipbuilding; you failed. If you have *habitus* of building sinking ships, you do not have a virtue of shipbuilding; you have a vice of shipbuilding, because you aren't building ships according to right reason, but contrary to it. Perhaps you keep drilling holes in the bottom of your ship; no one is going to hire you to build their ship, because you really suck at it. But if you build ships well, and you do so consistently, then people will consider you to be a good shipbuilder. You'll have a virtue of shipbuilding, because you have a *habitus* of building ships that fulfill their function: they float on the water, they don't sink, they have sails and rudders, etc. Similarly, Aristotle applies this to all categories and kinds of human acts. Take eating, for example. The first question to ask is always: what is the *telos* of this kind of act? The end sought by eating can be considered in several ways: biologically, it's clearly to obtain the nutrients and such which the body needs. We might also consider social functions, such as family bonding over a meal. But for now, let's consider the biological function. If the function of eating is nutrition of the body, then one vice would be eating too little (anorexia) and another vice would be eating too much/having an imbalanced diet (gluttony). And vice perpetuates itself: if you eat too much junk food and your body still needs more nutrients, you continue to be hungry, so you end up eating more the next time, but your body still hasn't gotten what it needs, so you get hungry, and the cycle continues. Same is true with other vices: since a vice fails to satisfy its *telos*, the desire for the satisfaction of that *telos* remains, so it prompts you to engage in that act—and thus that vice—more. There's a lot more that can be said, but suffice it to say that teleology is at the heart of Aristotelian virtue ethics, which is why MacIntyre talks about teleology in *After Virtue*, mentioning how the rejection of teleology in modern times has caused the present moral problems that Anscombe mentioned in *Modern Moral Philosophy.*

Does a fish see clearly when out of the water?

Anytime I open my eyes underwater, everything is blurry, but I can see fine otherwise. Is it the same way for a fish? Can they see fine underwater and then have trouble seeing out of the water? Is there even any way to test this?

When light moves from one medium to another, it refracts (distorts). The eye evolved underwater, so it evolved to have fluid inside it so light would move from the water into the eye without refraction. Your eyes have adapted to compensate for the refraction that happens when light goes from the air to the fluid inside your eyes. Underwater that refraction doesn't occur so the compensation ends up distorting the image. Fish would have a similar problem out of water. Since they aren't compensating for the refraction, they would also see a distorted image. Interestingly, since the eye developed underwater it's believed that fish generally have better eyesight than we do, since our eyes are basically underwater eyes that have had to be adjusted (imperfectly) to work on land.

How the US education system works.

Following on from a post about the British education system I saw a few days ago, how does the American system work? In particular: What is the SAT and the ACT? How does the college admissions system work? AT how old do you leave high school?

The details vary by school district (which can be as small as a few dozen students in one school to hundreds of thousands of students in dozens of schools), but generally: Ages 5-10: Elementary school (called Kindergarten through 5th grade) Ages 11-13: Middle school or (less commonly now) junior high school (called 6th grade through 8th grade) Ages 14-18: High school (called 9th grade through 12th grade) There are other options, such as private schools (you pay tuition for your kid to attend), charter schools (you sometimes pay tuition, sometimes it's district-funded), religious schools (mainly Christian, but there are variations), magnet schools (schools draw from a wide region to bring in the students they want, often with a specific interest like science or arts), and homeschooling. At 16-17, all students that want to attend college take the SATs. It's a long standardized test that tests writing, math, and reading skills. It's used so colleges can compare students from different schools on the same metric, which they can't do with GPA because schools make up their own formula for GPA, grading varies by teacher, and high schools vary by academic rigor. The ACT is a similar standardized test, though it's not as widely taken, it's not mandatory for pretty much any school, and the grading scale is different. For college admissions, you pay a fee to each school and submit your GPA, SAT scores, various essays, demographic information (race, religion, nationality, etc) and a resume of achievements and extracurricular activities. They wade through thousands of these applications and pick a group of people to admit, a small group to waitlist, and then everyone else is rejected. As the accepted students make their decisions, a few people from the waitlist are offered admission. Once they have the class size that they want, the rest of the waitlist is rejected. Some schools also hold interviews, but that's less common now because there's so many applications to get through.

ELI5: How do people undergo psychiatric testing for court purposes? Don't they know the are being tested and can influence the results?

Psychologists administer a test known as the MMPI (Minnesota Multiphasic Personality Inventory). The MMPI is approximately 500 questions (the short form is approximately 320 questions). The MMPI consists of several scales that measure several psychological disorders. This includes schizophrenia and other psychiatric disorders (which is most common reason one would not be psychologically fit to stand trial). Some of these scales are internal validity scales. These scales can measure whether the individuals answers are consistent. The scales can also measure whether someone is "Faking Good" (answering questions to make themselves look psychologically well-adjusted) or are "Faking Bad" (answering questions to make themselves look psychologically maladjusted). The Faking Bad questions are consist of questions that are not typically seen even within clinical inpatients with psychotic disorders. Thus, endorsement of such questions means that they are almost certainly lying about their symptoms (based on and compared to normed data from clinical inpatient populations with verified psychotic disorders) Source: Have Masters Degree in Clinical Psychology

CMV: "Free Speech Zones" and "Protest Permits" for political rallies are in direct violation of the Bill of Rights

The 1st Amendment to the US Constitution (Bill of Rights) is written as such: > "Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances." Congress shall make NO LAW RESPECTING the right to peaceably assemble, AND to petition the government the government for a redress of grievances. Firstoff, I think it's important to remember that these Amendments were written to prohibit government from making laws. They were not written to GIVE citizens rights. The government does not have rights until they are given to the government by the people. So the burden of government is to prove that they have the right to create the law. The purpose of the amendment, in regards to preserving the right to peaceably assemble, is specifically for the purpose of petitioning the government for a redress of grievances in a public manner. The amendment DOES so by PROHIBITING the government from making ANY LAW in respect to this "inalienable right". Now, this has been circumvented by applying "Time, Place, And Manner" restrictions. The very concept of a "restriction" is antithetical to the verbiage of the amendment itself, BUT... Even if we're to look at the precedence set by SCOTUS rulings, I don't believe they adequately or honestly address the particulars of this issue, nor do they meet the requirements set by the very specific language of the amendment. > Such time, place, and manner restrictions can take the form of requirements to obtain a permit for an assembly.[7] The Supreme Court has held that it is constitutionally permissible for the government to require that a permit for an assembly be obtained in advance.[8] The government can also make special regulations that impose additional requirements for assemblies that take place near major public events.[9] The SCOTUS rulings which attempt to abridge the right to public gathering and petitioning do so by claiming that there are other options and thus the right to free speech/ petition is not WHOLLY abridged. They also attempt to utilize partiality as a measure (a permit cannot be be turned down based on the content and purpose of the rally). They also often attempt to claim a security issue. - 1st: the amendment doesn't suggest anything about the QUANTITY of free speech. - 2nd: if the violation is an attempt to enforce "security", then the burden of proof is on those imposing the law to show a lack of security and that provisions would increase security. - 3rd: Several of the referenced SCOTUS rulings appear to relate to the right to "Parade" or use a public space for festivities. This does not appear to be in line with this particular aspect of the amendment which refers to political speech. CMV! _____ > *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)****! If you are thinking about submitting a CMV yourself, please have a look through our* ***[popular topics wiki](http://www.reddit.com/r/changemyview/wiki/populartopics)*** *first. Any questions or concerns? Feel free to* ***[message us](http://www.reddit.com/message/compose?to=/r/changemyview)***. *Happy CMVing!*

It comes down to the need to balance the right of various to individuals to assemble and speak, and the necessity for public property to actually be accessible to the public. The courts have ruled time and again that, while Constitutional rights are natural rights which cannot be removed from an individual without due process of law, rights can be subject to "reasonable" restrictions in order to preserve the rights of all. Here's a hypothetical. Lets say we have a city square which doesn't require a permit to rally or protest in. In this square a group of congregants from a local synagogue have decided to rally so that their voices might be heard by the public. However, a local Klan chapter catches wind of this and is able to mobilize to the same location, on the same day, at the same time, with double the people. They Klan hosts a counter demonstration in the same exact location as the Jewish folks. Now the question is who has the greater right to speak freely and have their voices heard? The Klan because the have more people? The answer is they both have the same right and the best way to ensure that they both are able to say what they want is via a permitting system. As long as permits cannot be denied for reasons other than schedule conflicts they do not inherently limit free speech and, in fact, can serve to ensure that everyone has the ability to speak freely.

ELI5: Why is climate change believed to be false and lumped with the theory of evolution even though it has nothing to do with religion/God?

Recently read the front page article on how Alabama now has to teach evolution and climate change and was just wondering why they are put together when climate change doesn't involve religion in the way the theory of evolution does.

Believing in climate change, like evolution, comes with a few assumptions/related beliefs: 1) the success of humans is thus far only a blip on the overall timescale of our planet and is by no means guaranteed; and 2) altering an environment that has allowed humans to flourish could lead to disastrous consequences. These beliefs fly in the face of the egocentric worldview that the earth was made for humans.

[Toy Story] Under what circumstances can toys break the "rules" and reveal they are alive to people?

If Woody and the gang went far enough to expose themselves to Sid just to save Buzz's life, would they do it under other circumstances? If their owner was about to die and it was in the toys power to save them, even though the toy revealed itself to the owner in the process, would they still do it? How much do we know about the "rules" of Toys?

There are some conditions that need to be met before a toy can reveal themselves as living. First, and most importantly, there can only be one human around. Secondly, this human must have personal experience with the toy or toys, whether this experience is good or bad. Thirdly, this human must be in a consistent state of mind where their claim of living toys will not be taken seriously.

ELI5: what is the difference between the different forms of Chinese? (Mandarin, Cantonese, Simplified, Traditional)

Mandarin and Cantonese are often refered to as dialects. However this doesn't really doesn't show how different they are from each other. For example American English and British English are considered dialects of the English Language, but they can understand each other. This is not true with the Chinese Dialects. A person who speaks only Mandarin will be unable to understand the speech of someone speaking in Cantonese and vice versa. Sort of like an Italian and French speaker, there are some similarities, but not enough to get a more complex point across. It is common among linguists to refer to Mandarin and Cantonese as being two Languages in the Chinese Language Family. Also there are many just as mutually unintelligiable dialects other than those two. Mandarin was the dialect adopted by the Capital and spread through much of the country as a second dialect. Cantonese is a common dialect around Hong Kong. Hainanese is from the island of Hainan. Shanghainese is from around Shanghai. The Hokkien is another common dialect from the South. People often forget that China is around the size of Europe and with more people. What's different is that back in the ancient history of China, Emperor Qin Shi Huang managed to conquer all of China and unified the writing systems. All the dialects shared the same pictogram writing system. Sort of like how if read out loud, a German, an Italian and an Englishman would all read out 3+3=6 differently, but all agree on it's meaning. This system mutated much slower than alphabetic systems, but eventually evolved into Traditional Chinese Characters. However this system was in many areas needlessly complex. Using more strokes than is needed to tell even the most obscure characters apart. There have been several attempts to simplify the writing. However, when the Communist party took over, they had the power to actually implement one. As a result, Mainland China uses Simplified Chinese Characters, Singapore does too. Hong Kong, Taiwan and many of the Chinese Overseas still use Traditional Chinese characters. Simplified Chinese replaces certain characters in Traditional Chinese with a simpler for. The names and the meanings don't change, just how you write it. Essentially it's like changing the font on a typed alphabetic language. To give an example of the change consider the traditional character for fly: 飛 this requires many penstrokes to write. It's ok if the word fly is only ever used in poetry, but if in the modern era, if you are running an airport and everything has something to do with flying you can see why people might want to speed it up a bit. So they changed the character from 飛 to飞. Every time you would write the first character you instead write the second one. Chinese characters are also made up of sub-components called radicals. Simplified Chinese simplified some radicals. Consider the Traditional character for say and poetry 說 and 詩, notice how the entire left side is the same. In Simplified they are 说 and 诗

ELI5:Why is Israel pissed off with the Iran Nuke deal?

I would think that a deal saying Iran can't produce a nuclear weapon would be something Israel would be all for, but yet they seem pretty upset about it.

As with almost all foreign policy pronouncements, you should consider what audience is being targeted and what the speaker's incentives are. In this case, there are good strategic incentives for Israel/Netanyahu to appear hardline on this deal. First, Netanyahu's domestic political situation is dependent on him being seen as hardline on Iran. He has staked his reputation on this position and so, *whatever deal was agreed to*, he has to appear more hardline than that. So, even if he actually thinks that this is a good deal, or a step along the way to a good deal (good in terms of what Iran would eventually accept), he has to publicly appear "pissed off", using OP's language. Second, there is the international audience. The P5+1 negotiators (from the United States, Britain, China, Russia, France and Germany) will be able to get a better deal from Iran if they can point to a hardline Israel stance and say to Iran, "Look, look at the pressure we are under here. If you don't want Israel to reject the deal (and maybe unilaterally bomb your nuclear facilities), you are going to have to give a better deal". The P5+1 negotiators also seem more reasonable and moderate next to a hardline Israel. In addition to strategic incentives, there is a thing called "fundamental attribution error". Briefly, this is a psychological phenomenon that all humans are subject to to some extent, where you think that you are a good person and forced to do bad things by your environment, but other people do bad things because they are bad people. So, even though Israelis trust themselves to only use their nuclear weapons defensively, they think that Iran would use nuclear weapons offensively, even if that means effectively committing suicide (through nuclear retaliation). This means that they are far more concerned about *ensuring* Iran doesn't have nuclear weapon capabilities than is reasonable/rational. These are the most basic and plausible explanations for why Israel is pissed off with the Iran Nuke deal. There are other possibilities but they are more complicated.

ELI5:Can someone help me understand how crossing the legs impacts when measuring blood pressure

Crossing legs, crouching, or otherwise increasing peripheral vascular resistance will cause a slight increase in blood pressure due to the increased pressure required to force blood through slightly crooked arteries.

[X-Men] why is Forge considered superhuman for his intelligence, but Richards and Stark generally aren't? What are the upper limits of his "powers"?

Edit: so I understand now that he creates things intuitively. But can he decide what he makes, or does he just put things together and then find out at the end what he made? Abs if he can decide, does he need all the parts easily available, or can he also intuitively know that he needs to buy 8 Tesla coils, 944 screws, and 439 yards of copper wire, etc?

Richards and Stark understand the underlying science behind their inventions. They could teach a class on the things they've discovered, if there existed other people who could keep up. Forge cannot do that. He couldn't teach you how to build one of his machines anymore than Cyclopes could teach you how to turn your eyes into interdimensional punch portals.

I am sorry if this is inappropriate to ask but are PhD salaries enough to sustain your living?

I am so sorry if this is inappropriate to talk about but especially in the US, are PhD salaries enough? If this is inappropriate, just tell me and I’ll delete the post. Or do I might need a second source of income? And if so, how would it be with the visa? I think 20hrs/week is given by visa and would just working in the uni be enough? And for other countries, how is the situation there? Please answer the question just depending on PhD salaries and no other source of income (no family backup etc). Ive been hearing “PhD salary wont be enough for you to live your life there(being the US), you need another income; you can’t afford going there” etc so I thought I’d ask for people who have experienced this. Edit: I reaally really appreciate your answers! You don’t have to write down the numbers, or the city, area you live in. I just want to get an idea of living abroad and studying PhD. To be more clear about your answer, I’d appreciate if you say “I live in a coastal area; I live in a big city; I live in rural areas...” and I’d appreciate if your salary is enough or not. I know it depends on certain things but I just want to get an overall idea. Thank you so much!

It can depend a bit on field and where the school is. In general, if you’re getting a salary from the school, it’s intended to be enough to live on, but, especially in big cities with a high cost of living, it can be a bit short. It may mean living with a lot of roommates far away from campus to find an affordable rent, or living on cheap food, or needing family to pay for a trip home. In many cases, a second job isn’t allowed. A PhD student is being paid, in large part, to focus on their research, so a second job would be a conflict. When the PhD salary isn’t enough, some people take out loans, and the truth is that a lot of people make up the gap with a little help from their family (which, obviously, is a problem for people whose families can’t afford that).

ELI5:Why, when I've done nothing wrong, do I feel guilty when passing by a cop? What's the psychology behind it?

You evaluate a threat using two criteria: intent and capability. "Does this person want to harm me? Does this person have the ability to harm me?" Law enforcement officers score high on both these scales. In terms of intent, the police might not have any desire to harm you physically, but they are motivated to harm you financially by issuing a traffic ticket, for instance. For capability, they peg the needle. You know for a fact that they have the tools and authority to fine, detain, or even kill you. It's a rational response to be wary of the police, because in rational terms, they are somewhat more motivated to do you harm than an average person, and far, far better equipped to do it.

ELI5: How does quantum computing work?

Regular computers store the values of 0 and 1. To represent a series of numbers, they must store them all, like this. 000 001 010 011 100 101 110 111 Quantum computers store numbers as 0, 1, or 'superposition', which is 0 and 1 at the same time (Q). This means that they can save the same range of numbers as QQQ. This not only saves memory storage, it dramatically speeds up some math problems. Imagine needing the answers to all of the above numbers multiplied by 00, 01, 10, and 11. In a standard computer, you need to do each math operation, with a quantum computer you do one operation. QQQQ x QQ.

ELI5: In quantum mechanics, what does it mean for something to be "observed"?

[This post](http://www.reddit.com/r/funny/comments/1krtbt/so_thats_how_usb_plugs_work/) made me wonder — what does it mean for something to be "observed"? I tried Googling around for it and ended up more confused than when I started, so hopefully somebody here can help shed some light. Thanks!

The word observed is used because typically we're measuring a property of something very tiny, which tells us about it. We "observe" its existence by measuring it's velocity or position. The trouble is, to get that information, to measure it, we have to interact with it in some way. Since the world of quantum mechanics is so tiny, we don't know of any ways to interact with it in a way that we get meaningful information without disturbing it's state. Think of small particles as very shy. If you observe them, they'll notice and change what they're doing because you're watching them. Whereas if you observe a cat, it won't care and will continue about its business. That's the main difference between normal observation and observing things in the world of quantum mechanics. Hopefully that helps clear up your confusion. TL;DR - Observing in the quantum sense means disturbing something in a way that you get information.

Why is good quality vision called '20/20' vision, and not 100% vision?

20/20 basically just means you can see what a 'normal person' should see at a range of 20 feet, from 20 feet away. It means you have normal eyesight. Perfect eyesight can be a lot better than 20/20. You can have 30/20 vision, meaning you can read what a normal person sees from 20 feet away, from 30 feet away, for instance. It's not uncommon for people who have had corrective eye surgery to come out of it with better than 20/20 vision.

CMV: I believe people are capable of being prejudiced against robots or artificially intelligent beings, and that that prejudice is a type of racism. Racism against robots is a social issue we will have to deal with in the future.

First, I will acknowledge that robots are not a human race, and that you might think it's silly to call prejudice against robots racism. However, sociologists consider islamophobia to be a type of racism, despite Islam not being a race. In this way, prejudice against robots could be considered a type of racism, as it uses racist ideas about "us" vs. "them", etc. People will likely form prejudices against robots as we continue to automate. The luddites destroyed looms during the industrial revolution, and similarly, humans will have prejudiced beliefs about artificially intelligent human beings. I believe that if a robot has sentience and sapience, then it qualifies as a being deserving of moral status. It follows that since racism is immoral (as it violates someone's freedom of identity), that if robots properly possess identity, then prejudice against them will infringe on that, and thus racism towards robots is immoral. _____ > *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)****! If you are thinking about submitting a CMV yourself, please have a look through our* ***[popular topics wiki](http://www.reddit.com/r/changemyview/wiki/populartopics)*** *first. Any questions or concerns? Feel free to* ***[message us](http://www.reddit.com/message/compose?to=/r/changemyview)***. *Happy CMVing!*

I would probably use the word prejudice to describe it instead of racism. But this is a very hypothetical question. We do not have any artificial beings which have anything close to sentience and sapience. Certainly nothing which is self directing and has free will. Whether that discrimination were immoral would depend on the very specific facts of what that artificial being's nature is. Discrimination based on race is considered immoral because race has nothing to do with any morally relevant quality of humanity. It is likely that an artificial being would have facts about it that are relevant to morality, and discrimination based on and directly related to those facts would be appropriate.

ELI5: How are animals able to drink water from puddles from the road, dirty ponds, etc. etc. But if we were to do it, we'd fall terribly sick?

In part it's immunity gained by getting ill once, or a few times and surviving it. The immune system remembers what foreign organisms it encountered before and fights them a lot faster and efficiently when an infection happens again (with exceptions from the rule, not all pathogens produce a lasting immunity). In part it's evolution at work. The wolf that couldn't handle half-rotten meat simply didn't live long enough to reproduce. Disadvantages like that get culled very quickly in nature. Most people living today have a genetic immunity to illnesses that were devastating a few generations earlier. The Spanish Flu wouldn't be as bad today as it was 1918 because we're the descendants of the survivors. If there are few water sources, then those have an advantage who can use even the dirtiest puddle without major consequences. But, you also only see the animals drinking, not hiding in the undergrowth puking their souls out, or dying prematurely from infections and poison. Just because they drink something doesn't mean it's automatically ok for them to do so. If there's nothing better to be had, they'll go for it and hope for the best, not like they can go to the next convenience store and buy a bottle of water instead.

What exactly is information?

In regards to the holographic principle, when physicists state that information is conserved in a black hole, what do they mean by "information?" How is information different than energy?

The existing answers address what information is in the context of information theory, but do not address what is meant by physicists when discussing whether or not information is conserved in black hole dynamics. This is actually something a little different. In quantum mechanics, an initial quantum state evolves over time into a new quantum state, but it is one of the essential features of quantum mechanics that no two initial states can evolve into the same final state. This comes from a property called *unitarity*. Thus, the final quantum state tells you what the initial quantum state was; it is in this sense that the information is preserved. The problem to be addressed with black holes is this. In general relativity, a black hole is completely specified by its mass, charge, and angular momentum. Consequently, two different systems -- but which happened to have the same mass, charge, and angular momentum -- can collapse into identical black holes. This contradicts the principles of quantum mechanics. This problem was exacerbated by the results of Hawking's first calculation showing black holes radiate ("Hawking radiation"), because the radiation emitted was a perfect blackbody spectrum, and thus when the black hole evaporates and returns to just a bunch of particles, that final quantum state again will preserve no record of what the initial quantum state was that led to the creation of the black hole in the first place. Thus, we had two ideas in conflict with each other: that two states cannot evolve into the same state (an essential principle of quantum mechanics), and the result that black holes keep no record of what produced them. While there have been various ideas on how to approach this problem, the general thinking is that there are degrees of freedom in classical general relativity that have been ignored, and that when you keep track of these, the black hole will keep a record of the state that created it and that the final radiation will not be a pure blackbody spectrum, but will in fact have a signature that depends on the original state that led to the black hole. However, this is not a certainty, and this problem has not yet been resolved once and for all. Edit: minor fix: "does"-->"do"

ELI5: If insider trading is illegal, how are CEOs allowed to trade shares of their own companies?

Most executives are governed by rules regarding insider trading, which are set by the company through bylaws or individual agreements with the executives. Normally, they state the times when you can and cannot trade in reference to when certain pieces of information are about to be released. For example, you are probably not allowed to trade a certain amount of days before financial statements are about to be published publicly. If they're caught violating these laws, they'll be fired from the company (most likely), and the SEC will likely have some words with them as well. Edit: To clarify, the agreements restrict their trading, usually, before and after major company events. Often times, executives will clear it with the Board of Directors for any large trading in their own company. By being candid in their intent to trade, they're helping to cover themselves from being accused of insider trading.

If the heat death occurs, how can time itself stop?

Since space and time is the same thing, how can time stop if the heat death occurs? The low energy particles evenly distributed in the universe would still be distributed in space, with space between them. Right?

Love this question! This is where metaphysics and philosophy blend. Also, a classic question becomes metaphysically/philosophically beautiful! If a tree falls in the forest, does it make a sound? Most people answer yes. What you're saying is that it exists independent of our observation. Relating back to the bigger question, you're saying that our understanding of time is the disorder of energy and the spreading of energy; that our definition of time is the ability and existence of energy transfer. Well, the only real reason for understanding time like that is because that's the only way we have/ may ever comprehend time. Once all energy stops transferring (we're dead), who's to say that energy transfer is time anyway? Sure that's the only way we comprehend it, but it could be something entirely different and not understandable to us. So to answer your question, maybe (like almost every other metaphysical question's answer). Tl;Dr Just because energy transfer is our way of observing/comprehending time, doesn't mean that that is what time is.

[General]When it comes down to the core 'Science' in Science Fiction, which universe has the greatest integrity in its fictional physics and application?

I don't want to exclude iterations of 'magic' from this, but it seems when it comes to most instances that have it magic is simply an unexplained, or vaguely explained, thing that isn't questioned. This could also be applied in same aspect to far off science fiction wherein everything works because its just 'technology.'

A lot of Michael Crichton's books have at least some foundation in real world theories and possibilities. Some of the books are simply conversations about the implications of a new technology that just happen to be set in a thrilling narrative.

ELI5: If the first living beings reproduced asexually, how did diverse species came to be? Also how did sexual reproduction started?

I understand that the first living beings were unicellular organisms, prokaryotes, which reproduce asexually. If DNA was only "cloned" from one organism to form an offsrping, how did different species appeared? I'm guessing it has to do with some kind of genetic mutation, but even then I can't wrap my mind around how sexual reproduction started.

Well it helps to look at species that have various forms of reproduction between asexual and our form of sexual reproduction. For instance prokaryotes can't go through meiosis but can incorporate new DNA from other prokaryotes. Then there are some yeast cells that can reproduce asexually or sexually when under great stress. Then there are various hemaphrodites in the animal kingdom. Then there are species that can change sexes like clownfish. Then there are true sexually dimorphic species like us. Do you have a more specific question. Edit: Also it helps to think that sexual reproduction (meiosis) is really just a modified version of asexual reproduction (mitosis) done twice. Then you just have specialization of specific parts and genders overtime.

[General Discussion] How are spaceships built in space?

That's a very broad question, but the short answer is "in pieces". At our kind of technology level, the quintessential example is the ISS. We built it in "modules" small enough to transport up to orbit using existing rockets, and then just bolted the modules together once they were up. This has the advantage of using our existing production facilities to make something bigger than we'd be able to get up to orbit if we were trying to do it in one go. The downside is that the resulting space stations are quite limited in design, and are still forced to be quite small. It will take us quite a long way to get there, but the next step would be to move much of the assembly process to an orbital "shipyard" - rather than shipping up completed modules, we'd send up the parts, and then assemble them there. This would let us make much bigger, much cooler spaceships. However, for this to be practical, a space elevator is probably a prerequisite. The logical progression from here is to move the entire manufacturing process into space. This would require asteroid mining to acquire the raw materials, and probably more efficient drive tech to actually collect them, but not having to contend with moving things into and out of a gravity well removes the biggest inefficiency from the process. At this point, the entire process is probably done entirely by robots, which removes the need for the work to be carried out either in a pressurised "drydock" or using spacesuits, which makes the whole thing a lot simpler as well. After that, we've moved out of the realms of hard SF, so it's hard to predict what would happen. Star Trek has shipyards that use replication technology to build most of the ship, which simplifies the supply chain considerably, but presumably at some point the civilisation in question stops being planet-based at all.

CMV: All the US flag apparel people wear and use around July 4th disrespects the flag itself

Background: -US Federal Law Code says the flag isn’t to be used for clothing. The code isn’t enforceable because of the 1st amendment. -American Legion says it’s okay to have the flag resembled on clothing. The flag is something to be honored and respected. It’s colors and design is not something you should use to cloth yourself. It’s not patriotic. Socks? You’re feet are on the ground, get dirty, and smell. Underwear/Swimsuits? You’re putting the flag’s colors and design next to your “netherlands”. Shirts? Your pits stink. Pants? You sit on them. Paper napkins/plates? You eat off that, wipe your face with it, and throw it away. This isn’t even taking into consideration all of this “patriotism” is really just commercialization of the flag and drives revenue. Why not just let the flag fly the way it’s supposed to? (you know… like a FLAG)

> Background: -US Federal Law Code says the flag isn’t to be used for clothing The code is that you don't take an **actual US flag** and cut it up to make a shirt, not that a shirt can't have stars and stripes imagery like the flag's design.

ELI5: If the affordable care act requires that people with pre-existing conditions can not be denied by private insurers, why wouldn't everyone just wait until they were sick and then purchase insurance?

You can only apply for insurance during "open enrollment periods" (the 2015 one ends February 15th) or under certain specific circumstances called "qualifying life events" (get married, be born, change jobs, things that might require you to change health insurance basically). If it's not an open enrollment period, and you aren't undergoing a qualifying life event, then you can't sign up for insurance and are out of luck if you get sick.

When genes change expression is this change simultaneous over the whole body or could genes in only certain cells change expression?

No, genes can be expressed in some cells but not others. This is how you get differentiation of cells, to create organs etc. It's not just in something large like the body that this happens, genes can be turned on in certain portions of a embryo, but not in others.

Economist roles in private firms - what does the job actually entail?

So.. i've recently graduated (a degree in pure economics) and keep seeing economist roles in a range of firms from visa the UK arts council. I would assume theres a good bit of statistical modelling in the job role, but that was a tiny part of my undergraduate degree and i certainly couldn't perform reliable regressions in a professional format outside of basic cross sectional, time series or logistic regression analysis. I guess the real question here is what does an economist do that an economist in academia doesn't and how can these skills be achieved?

Unfortunately what they want is for you to turn the data into meaningful **quantitative** information regarding their performance or forecasting future conditions. This requires knowledge of statistics or econometrics and statistical software skills, programing skills, data cleaning and visualization, etc

Why does squinting seem to improve our sight?

For people who don't have perfect eyesight, squinting is the substitute for getting contacts or glasses. How does this help our eyes focus on something we couldn't before? Is it because there's less surface area for our eyes to cover or???

Squinting helps eliminate non straight light rays entering the eye, this means the need for refracting or focusing of light which is non straight is reduced. In other words squinting acts like glasses by correcting refractory errors, someone who squints should be assessed to see if optics will helps their vision Edit: words

ELI5: how does the body regenerate blood after donating?

Also when the blood that has been donated is regenerated why/how does the body know it is back to its needed amount?

After you donate blood, the number of red blood cells in your blood decreases. Red blood cells are responsible for carrying oxygen and this decreased oxygen in the blood is a stimulus for the kidney to secrete the hormone erythropoietin. This then travels to the bone marrow and stimulates the production of more red blood cells. This is a great example of a negative feedback loop.

ELI5: How are private prisons legal?

I've been wondering how it's legal for a private organization to incarcerate a federal/state prisoner (or any prisoner of the government for that matter).

How is the government hiring a company to manage prisoners different from the government hiring guards to manage prisoners? The company does not decide who goes to prison or for how long, the government does. The government also sets the standards for how prisoners are to be treated, and has a responsibility to enforce those standards - just like it does for state-run prisons.

I have a cold and am curious, what defenses will the virus encounter (in order, from entry)?

First, there are physical barriers. Skin, for example. Then, assuming you got it through contact between your mucous membranes (mouth, nose, eyes) and particles containing the virus, there are antimicrobial agents in these mucous membranes (though most of these are geared toward being antibacterial, not antiviral) as well as the actual fluid (tears, saliva, mucous) presenting something of a barrier as well. Most colds are infections of the upper part of the throat. Viruses enter cells and begin to replicate inside them. Interestingly, most rhinoviruses use a receptor called ICAM1 to enter the cell, and up its production once they're inside. However, ICAM1 is also a signalling molecule, and it signals to macrophages (cells of the immune system) and starts a signalling cascade which leads to cytokine release, signalling, and imflammation, which gives you the local effects (sore throat) and broader effects like runny nose and fever. Furthermore, cells like leukocytes can phagocytose (essentially, eat) virus or destroy infected cells. These steps are generally referred to as cell-mediated immunity. Meanwhile, B-lymphocytes are running around. If a lymphocyte whose antibody matches the virus is found, that cell is activated (this requires interacting with a T "helper" cell). The B cell differentiates into "memory" B cells, that stay around to remember the antibody in case of reinfection later, and plasma cells, that divide rapidly and start churning out the antibody. This part is generally called humoral or antibody immunity. The antibodies bind to the virus, which prevents virus particles from getting into cells and identifies them to other players in the immune system which can come along and scoop them up. At this point, the infection is generally cleared rapidly, unless the person is immunocompromised.

CMV: If it comes to climate-induced migration, the nations with the highest emissions have a moral obligation to admit their share of refugees. Not doing so would be morally reprehensible.

In 2017 The Guardian wrote: ​ >Climate change 'will create world's biggest refugee crisis'. > >Tens of millions of people will be forced from their homes by climate change in the next decade, creating the biggest refugee crisis the world has ever seen, according to a new report. > >“If Europe thinks they have a problem with migration today … wait 20 years,” said retired US military corps brigadier general Stephen Cheney. “See what happens when climate change drives people out of Africa – the Sahel \[sub-Saharan area\] especially – and we’re talking now not just one or two million, but 10 or 20 \[million\]. They are not going to south Africa, they are going across the Mediterranean.” ​ Full article: [https://www.theguardian.com/environment/2017/nov/02/climate-change-will-create-worlds-biggest-refugee-crisis](https://www.theguardian.com/environment/2017/nov/02/climate-change-will-create-worlds-biggest-refugee-crisis) ​ If global warming reaches the stage where some coastal areas become uninhabitable, or if draughts with an unprecedented intensity plague a country, people will likely flee. The majority of countries affected will be developing countries that have contributed comparatively little to global warming, yet suffer the consequences the worst. USA, Europe, China, Brazil (and possibly others; consider this an incomplete list) have an obligation to help these people and offer them easy access to their countries, that doesn't involve potentially drowing in the Mediterranean Sea. ​ Complaining about their (refugees') crime potential, given how their standards of education and social progress are likely "behind" (to use a normative term) wealthier countires, and using that as a weapon to bar refugees from entering the country would have to be considered agitation. There's no judge who'll persecute you for making vast areas uninhabitable in other areas of the world, and few crimes compare to having your turf ripped away from you through no fault of your own, and solely because wealthier societies wouldn't dial back their harmful conduct. ​ Taking in climate refugees is (or will be) humane and moral and if ressources allow for it, a country should take in as many as possible. ​ ​ ​

If you have a nation that pollutes more due to geographic/economic/cultural factors, all other things equal, then by moving people into that nation you are increasing pollution more than you would otherwise. If there is already a feedback loop to pollution, then it's possible that by increasing the share of refugees to the 'worst' nations you are simply creating more global warming and therefore more refugees. Wouldn't the more rational choice be to limit additional emissions to prevent making the situation worse rather than seeking to 'punish' high-pollution nations in a way that also screws over the whole planet?

What does the Schrodinger equation mean and what does it tell us?

I am beginning quantum mechanics and we have been studying the Schrodinger equation pretty extensively. But I am confused about what this equation represents and why can't we derive it?

The time-dependent Schrodinger equation tells you how a quantum state vector evolves with time. It says that the Hamiltonian operator is the generator of translations in time. If you know the state vector at time t = 0, the Schrodinger equation and the Hamiltonian tell you what the state vector will be for all time. You can't derive the Schrodinger equation because it's a **postulate** of quantum mechanics. You can either postulate linear and unitary time evolution, and the TDSE follows, or you can just postulate the TDSE directly. Either way you're making an assumption about how quantum states evolve with time. This is a fundamental assumption to quantum mechanics, hence why you can't "derive" it.

CMV: It's not sexist to think that there are traits more common in women versus men and these same traits make you more likely to succeed in certain jobs and industries.

Modern psychology acknowledges differences in the mental functions and behaviors of the sexes. For example, males show greater affinity for violence. Studies have shown women are more empathetic. [https://en.wikipedia.org/wiki/Sex\_differences\_in\_psychology](https://en.wikipedia.org/wiki/Sex_differences_in_psychology) It's not saying women are not capable of violence, it's saying it's less probable. Therefore, if we can assume MMA requires people to be violent, then it will attract much more men than women. Countries with a generation of gender neutral and women empowerment policies have not succeeded in creating an equal outcome. ([https://www.bbc.com/worklife/article/20190831-the-paradox-of-working-in-the-worlds-most-equal-countries](https://www.bbc.com/worklife/article/20190831-the-paradox-of-working-in-the-worlds-most-equal-countries)) This either means there are things that these societies still need to improve, which I think is part of it. But more likely, when given freedom of choice and opportunities, there are certain types of people more attracted to, or suited for certain jobs. Sometimes there is an unequal distribution of them in either men or women. \*I use men or women in the biological definition for clarification.

I think it has more to do with the rationale behind believing certain traits are more common. Feminists would absolutely tell you that men have learned some traits and women have learned others because of the way culture has historically viewed men and women differently, and they would say that's a bad thing. It's kind of a self-fulfilling prophecy. If an entire population treats boys and girls fundamentally differently, then it won't be surprising if those boys and girls grow up having different characteristics. The issue is when you believe that women are just naturally not good at math, or that men are just naturally prone to violence. The fact that men and women grown up differently does not imply that men and women are naturally better at one thing than another. Furthermore, if men are better at a given thing because society has conditioned women to be bad at it (or vice versa), that's a huge problem and needs to be addressed. This is why feminists feel strongly about creating a culture that helps men and boys process emotions better, and where girls and women aren't judged for being "bossy," to give a couple examples.

ELI5: Why smartphones can't capture decent pictures of the moon/stars.

There are two main characteristics of a camera. How much light it collects, and for how long. In mechanical cameras, these are aperture size and shutter speed, respectively. Smartphone cameras do not have a shutter, but likely have something analogous. When the cameras are designed and manufactured, the engineers have to decide on a blend between ease of use and versatility. Your average person isn't going to want dozens of settings. They just want something they can point at an object and take a picture. They also are unlikely to have a background in photography, so even if those settings were there, they wouldn't really be able to take advantage of them. So the designers basically make a camera that will do fine under most normal situations, but taking pictures in extremes of light are mostly outside the realm of what these cameras are able to handle. It's a trade off between cost and expected use.

ELI5: why is blood pressure an important health metric? And how does sodium affect it?

High blood pressure can often indicate blockages in blood vessels, or hardened vessels, and this makes the heart work harder than it needs to. More work means the heart wears out faster. Sodium affects blood pressure because it pulls water from the body into the blood. More water means more blood volume, and that's higher blood pressure.

[Dc comics/Batman] What kind of certifications does Batman need to to fly the Batplane and what FAA rules does he break whenever he goes up?

Let's go with this version of the Batplane: http://imgur.com/a/tG0Na

Well in addition to pilot's license, whether it be Private or Commercial, the FAA requires a specific type rating to fly any aircraft weighing over 12,500 lbs and/or having a turbojet powerplant. Since the Batwing is a crazy bat-prototype a type rating probably doesn't even exist so Batman would be flying it illegally every time. Not to mention obviously breaking laws and Federal Aviation Regulations such mounting operational weaponry on a non military aircraft, exceeding airspeed limits below 10,000 feet (250 knots indicated airspeed), airspace entry violations..pretty much everything just look up FAA FAR Part 91 and you'll get the idea, even if he qualifies as per Part 61. But this is The Batman's Batplane and is some sekret documents Wayne proto military shit nobody is supposed to know about, basically nobody can see him on radar or do anything to stop his Batplane since they only know it exists for the 2 seconds before their face has a bat shaped boot print embedded in it and the plane has flown off in the recently repaired autopilot. TL,DR: The only law the Batman isn't breaking in the Batwing is smuggling drugs into the country.

Why does an excess of neutrons make an atomic nucleus unstable?

From what I've learned on the net, larger nuclei are less stable than smaller ones. This is apparently because larger nuclei have more protons, meaning that their compounding repulsive forces eventually overcome the strong nuclear force that 'glues' a nucleus together. So why is it that increasing a nucleus' size with just **neutrons** also causes it to become unstable? Additional neutrons are not supplying any additional repulsive forces like protons would, and as far as I know, more nucleons should bring with them more strong force 'glue' to hold the nucleus together. I.e, the nucleus ought to grow *more* stable. Is there any explanation for this? Is it an unexplained phenomenon? Thanks for your time!

For very large nuclei the models become more complicated and nuanced, but for intermediately sized nuclei a relatively simple model called the shell model works pretty well. According to the shell model protons and neutrons in nuclei occupy energy levels similar to the electron energy levels in a hydrogen atom. However, since protons and neutrons are distinguishable fermions, the tower of energy levels they occupy are independent. This means that the lowest energy levels can be simultaneously occupied by neutrons and protons since they aren't indistinguishable. If you add lots of neutrons to a nucleus, they are forced to fill up increasingly higher levels, while there are lower levels available to protons. The nucleus can therefore lower its energy by converting neutrons to protons via beta decay, and this is why these neutron rich nuclei unstable.

How detailed are reflections in mirrors?

If you were to zoom in on a mirror, just how detailed could the reflection be? Would it get blurry and fuzzy like when you try to zoom in on a picture? Or could you zoom in far enough and see atoms? (this is all assuming you have a mirror with 100% reflectivity and a good enough camera or microscope to zoom on atoms)

For most practical purposes (looking at light and visible things) the answer is that the mirror is infinitely detailed, given your assumption that the mirror is flawless. Hypothetically speaking, you couldn't zoom in to the mirror to the atomic scale, you'd end up looking at the atoms of the mirror. However, you could look into a mirror reflecting a magnifying lens which will show you atoms of the object you're interested in. Of course you can't actually see atoms, they're too impossibly small. When taking about looking at atoms you're usually talking about electron microscopes of some kind, these machines use magnetic lenses to do the work done by glass in an optical microscope.

Eli5: How come humans need around 1,500-2000calories for basic survival of the Body but people suffering from severe anorexia can carry on for years eating a lot less.

1500 to 2000 calories is what the body needs to remain healthy. Less than that and the body begins cannibalizing non essential things. It starts with fat stores, then it goes to muscles. All in the name of keeping energy supplied to the vital organs. Severe anorexics will consume just enough calories to keep their brain, heart, and lungs functioning but their body will essentially be digesting itself. That's why you'll see malnourished people looking like skeletons with skin stretched over the bones. Their muscles are barely there anymore.

CMV: Racial color blindness does not advance racial justice

There seems to be a widespread opinion, on both the right and on the left, that political discourse that is about racial groups or policies that are constructed around racial categories fundamentally undermine a project of social justice. The idea is that by talking about race, we are perpetuating racial division, and that if we ever want racial inequality to go away, we need to stop talking about race. Another formulation of this position is that racial politics or policy constructed around race is a form of "identity politics," and that, as a form of "identity politics," something to be opposed in favor of a more universalist discourse. I find this line of thought very unpersuasive. Simply put, race matters. It is a social construction, and, at the same time, is socially real. We need to talk about racial inequality and use racial categories in our policies if we want to address problems caused by racism. For example, if we want to fix racial inequality in education, we need to be able to talk about the racial factors that disadvantage many black communities in the United States--we cannot just talk about economic inequality, we need to also talk about stereotype threat and racial bias, etc. Similarly, we cannot address mass incarceration of black men in America without talking about the racial dimension to the issue. \----- Edit (06/19/2018, 7:18pm EST): I've read through a lot of thoughtful responses here. Still, my view has not really been changed. Here are a few stuck points: * The idea that talking about race or policies around race make race more "real" than it already is. Any backlash effects are, I would argue, trivial compared to the ways that race already shapes social life. * The idea that there is a single factor that is core to inequality, that, if we could just construct policy around this universal factor, everyone would come out equal. I do not think any such universal factor exists unless you get extremely amorphous, philosophical, and circular by pointing to a factor like "power." * That race is not, itself, a factor in determining unequal outcomes. I think if I could be dislodged from any of these points my view would change. But so far, I have not seen evidence that works for me. As a tip for commenters, I've really appreciated those who have cited scientific articles! I tend to find those more compelling. \--- Edit 2 (9:39pm): As a bit of a mid-mortem on this conversation, I think a good take away of my changed view is that there are possible, extreme examples where a colorblind approach is preferable to a race-attentive approach. However, overall, I remain firmly committed to the idea that colorblindness is not, in general, the preferable option. Instead, I continue to see that "colorblindness" or the myth of a post-racial world function rhetorically in a way that is very fascinating: these ideas can be used to suggest that it is anti-racists who are the real racists! This thread is an excellent specimen of this kind of rhetoric. I also think that there's an element of emotion that the idea of being called "racist" that isn't going fully acknowledged here. For some people, being called racist is the same as being condemned as a "bad person." And I don't think that talking about race, or thinking about the way race operates in someones life, should be reduced to a question of "am I racist, or am I colorblind?" These things are, no pun intended, not so black and white. We all exist on a continuum to which our behavior is effected by the idea race. But we need to think about race in a frank, unmoralistic way if we are going to locate ourselves on that continuum.

> Simply put, race matters. Right, but it *should not*. That should be the ultimate goal: a society where race does not matter. Sure, in the short term, we should still consider race. But in the short term only - as a way to remedy past wrongs. We should not lose the endgame of a colorblind society.

How is it that my computer can load multiple files at the same time, if there's only one "needle" in my hardrive?

How can you see everything around you when you only have 2 eyes? The read head only picks-up chunks of data at a time. Any software that requests for an entire file in one go will lock your system, so they don't do that. Since they only ask for chunks at a time it means any number of files can be read or written to the hdd by any number of programs... but if it so happens that a few programs decide to do some intensive read/write action you'll notice the OS being slow and / or those programs being unresponsive. It's the same multitasking paradigm as the underlying operating system itself. It's all just time-share.

Recommended Reading on Consciousness, Self Awareness, and Intelligence

I hope this is an OK question.   I am helping to teach (TA) a course on machine learning and artificial intelligence where we go over some compare and contrast with nature on a more "hard science" level (natural neural networks vs. artificial neural networks / AI's performance on simple cognitive tasks vs. animals or humans ).   There seems to be considerable interest by a minority of students to explore some of the more philosophical aspects of consciousness, self awareness, and general intelligence. Although that is somewhat outside the scope of the course, we provide further reading material (select readings re: Aristotle, Decartes, Locke, Leibniz, and several others all the way to Freud) ; however, because many have little or no formal exposure to philosophy, they are finding some of the readings difficult or dense. For background, it is a survey course in computer science, not philosophy, but we cover some ethical concerns with data science, machine learning, and AI. That and people are concerned that AI will become conscious and do strange things (no comment from me on this one).   **Questions:** (1) What would you recommend as readings for the subjects of consciousness, awareness, and/or intelligence which are either good overviews or introductions?   (2) What are good reads in philosophy which specifically address "artificial" consciousness, awareness, intelligence?   Thank you!

(1) David Chalmers - *The Puzzle of Conscious Experience,* David Chalmers *- Facing Up to The Problem of Consciousness,* Thomas Nagel - *What Is It Like To Be A Bat?,* David M. Rosenthal *- Two Concepts of Consciousness,* Dennett - *Consciousness: How much is that in real money?*, Putnam - *The Nature of Mental States,* Dennett *- Explaining The "Magic" of Consciousness,* William Seager *- Could Consciousness Be an Illusion?* Any reading that distinguishes between access and phenomenal consciousness, self-aware and high-order theories of consciousness, representational theories, and more simple theories, such as those which grant any organism that is perceptually aware to be conscious. (2) John Searle - *Minds, Brains, and Programs*, Andy Clark and Josefa Toribio - *Doing without Representing*?, Michael Pauen - *Reality and Representation: Qualia, Computers, and the "Explanatory Gap"*, Rajakishore Nath - *Machine Consciousness, Mind & Consciousness*

ELI5: If my body gets a fever to fight and kill an infection in my body, why is it OK to take Advil to reduce my fever? Doesn't that counteract what my body is naturally doing?

First, some background: Advil is an inhibitor of the cyclooxygenase pathway, which normally creates prostaglandins (some of which are pro-inflammatory, some of which are ant-inflammatory). Prostaglandin PGE2 ultimately induces the fever portion of your body's immune reaction, so when you take Advil or other NSAIDs, you fight off the fever by inhibiting the production of a molecule that leads to fever production. Now, to your question of why it's okay to take it: Prostaglandins are just a small part of your body's immune reaction. While increased body temperature can help fight infection as several other people have mentioned, it is not important enough in most cases to cause you great harm if you inhibit it as there are plenty of other parts of your immune system that are not inhibited by NSAIDs. So, in short, NSAIDs do work against your immune system, but only weakly. Hope that helps

How can chip manufacturers like Intel, AMD, and Apple keep giving huge improvements on performance every few months by changing the architecture?

I recently saw the comparison chart for the new M1X chips which give 50% improvement over the previous generation. I'm wondering if the semiconductor size remains the same and the die size is the same as well, then how can they manage to just keep changing the architecture every so often. If the architecture change takes so little time, then why don't all companies have the same performance? Is it just the chip architecture they change or is it something else as well?

There's a lot that goes into a new architecture (or micro-architecture as we usually call it). You can also play a lot of games with "50% improvement" (for example, is that power/performance?) Part of it is smaller transistors. It can come from a bigger die size (although that is more expensive). Other than that, you can increase the size of structures on the chip (buffers and schedulers - as well as memory blocks). You can also change the algorithms you are using, to be smarter about processing instructions or prefetching data.

ELI5: What is the point of the "do not write in this shaded area" thing on tests?

I recently took the act, and on the first page there was a tiny box that said "do not write in this area" with nothing else in it. What is the point of that?

Most of those tests get pumped into a machine that scans it and marks your test, if there are pencil marks where the machine is not programmed to look it will probably mark it as an incorrect answer or cause an error in the machine

[Star Wars] How bad is life under the Empire for the average joe?

It depends a lot on what planet you are on and what species you are. If you're on Coruscant, it's probably indistinguishable from the heyday of the Old Republic, but with more racism against non-humans. If you're non-human, you're more likely to get shunned to the slummy lower levels. If you're on a fairly important and independent planet, like Corelia, you'll witness a lot of aggravating police-state actions. Imperials insert themselves into government and law enforcement, against the will of the people, perform warrantless raids on anyone they suspect could be a rebel sympathizer, that sort of thing. If you're on an unimportant planet, things are probably fine. There's probably some local Imperial governor, but they probably don't really have enough power to affect most people's lives. Without having some interest in either acquiring or eliminating something, the Empire is simply too busy to go around mucking with the lives of average yokels. If you're a Noghri of the planet Honoghr, then your homeworld was deliberately contaminated and kept in a state of ecological disaster by the Empire. The Empire tricked the Noghri into providing their services as skilled assassins, by convincing them that they were helping repair their world, when in fact they were making sure it remained dependent on the Empire. If you're on Thyferra, the supplier of bacta (super medicine), then you're living the dream, because you are such a hot commodity that the Empire will even tolerate you playing both sides of galactic conflict. You're making money hand over fist. If you're an Alderaan, then your life will be very explodey and abbreviated.

[Superman] What is Superman's relationship with Metropolis PD like?

We know Batman's relationship with the GCPD. Has an ally with Gordon most of the time. Some officers don't like him but most of them support his actions. Is it the same with Metropolis? Are they receptive when he flies down with a baddie for lockup?

It varies over time, though tends towards the positive. By the time his career is in full swing, he's gone a long way to build credibility with local authorities as a guy earnestly trying to help. Another advantage he has is Clark Kent, Ace Reporter; while Batman doesn't really have an excuse to be shoving his nose in people's business, it's perfectly reasonable for a reporter to be sniffing about, allowing Superman to compartmentalize that element of vigilante work from his hero persona. There are exceptions, though. Some of the cops take the view that Superman can't be trusted, or demands greater scrutiny. Other cops could be under the influence of villains, like Lex Luthor. And sometimes, Superman manages to screw up badly enough to spoil the entire thing, like the time in the Animated Series where he gets brainwashed by Darkseid and used to invade Metropolis.

ELI5: Why doesn't a garden-hose eventually explode even when the tap is on and the nozzle on the other end is shut-off/closed?

Like when you're watering your lawn and plants, then forget to turn it off, and don't notice for a couple of days, why doesn't the hose or anything eventually explode? Probably has to do with the plumbing, if so, how?

Your plumbing supplies water at a certain maximum pressure. That pressure is lower than the pressure required to stretch the hose. So it's less like blowing up a balloon, and more like blowing through a pinched straw. No matter how hard your lungs can blow, the straw's not going to explode.

ELI5: How do night vision goggles work?

There are several ways: * Infrared: There are electronics that can see "color" lower than red. As things and beings radiate those colors as heat, you can use it to see in the dark. Also, as infrared is invisible to the human eye those night vision devices can be enhanced with a "infrared flashlight". It works like with normal light, just in an invisible part of the spectrum that then is shown to you in a visible one. Heat vision and "infrared just below the red" are actually two different beasts, but for this scope here saying "light below your visibility" is sufficeient. * Enhancement of the existing light. For example electronics that are more sensible than your eyes and that light is then enhanced. But what you usually mean is expalined by mainman879, photons hit a place in a vacuum tube, those cause a shower of electrons which fall on a plate that gets flourescent in those places and that you can see.

Same school for PhD

Currently, I’m an undergrad in STEM. I’ve been thinking about staying at the same university for my PhD (right after undergrad) but I want opinions on whether the benefits outweigh the detriments. I love my university, it’s a great fit for me and a great university (R1). I love this city too, and my partner’s family is here (and mine is only a few hours drive away). I originally planned on going to a different university, but the main reason I’m thinking about changing my mind lately is my current lab: my PI is, for lack of a better term, a big shot in my field, and this research is what I want to continue my career in. The lab culture is super healthy and respectful, which is honestly what I value most. I’ve heard countless horror stories about toxic labs making peoples lives miserable. I don’t want to go to a new lab and find myself in that situation. Would this hurt my chances of getting a job (postdoc) afterwards? Do universities prefer people who did their undergrad and PhD at different schools?

It's no issue at all, as your undergrad really isn't factored in to your "Research career". It's your PhD and subsequent post-doc placements that are your "research years", and where its beneficial to have moved around.

ELI5: Why does fountain soda from the gas station seem to taste way better than bottled or canned soda?

Soda is created by taking a flavored syrup and carbonating it, which means adding carbon dioxide to create the bubbles. When it's bottled/canned, it's carbonated at the factory and sealed, sent to a store, and then you buy it, open it, and drink it. When you buy it from a fountain at a gas station or fast food place, the syrup is carbonated in the machine right before it goes into your cup. This "freshness" accounts for the difference in taste.

[Marvel/DC] Why is acid always stored in giant open vats?

The overwhelming majority of the time, hazardous chemicals used in large quantities are stored quite safely; you only really end up hearing about the few isolated incidents where they aren't and some accident results. The fact that they exist at all is a result of substandard working conditions in most low-paying factory environments and complete lack of safety compliance in illegal operations, the two situations that result in the largest number of accidents, particularly the latter amongst vigilantes and other superhumans. Nobody writes a news story about a manufacturing plant's safe working conditions. Doesn't sell papers.

How does cuteness work in humans? Why are people often more willing to protect cuter animals?

Basically, why do people find certain animals so cute? Why will some people sometimes take unnecessary risk to save an animal they find cute? EG a kitten over like a possum, or rat, or something. I've heard it's because they look like human infants, which is often true, but how about that baby duck, or even some insects? Or how about inanimate cute things, like plushie toys?

There's a relevant ted talk by daniel dennett that says essentially "cuteness is what we find cute, and cute is the quality of being something we want to help, like a baby. People who didn't find babies cute had their babies die so here we are"

CMV: trying a child as an adult makes the protections offered to children irrelevant and is downright vengeful

This is an issue I feel passionate about, but I also understand my views are not that developed. Very curious to say what the responses are! Juveniles are given special treatments in trials, there is a focus on rehabilitation an integration back into society. This makes a lot of sense to me, children are still learning and don't have much freedom in life. Many of their choices and actions are an immediate cause of their situation, and removing them from that could potentially help. Not to mention, the focus on punishment in adult courts can likely lead to training a kid to be an offender for life, Trying a kid as an adult circumvents all of that, and ignores the fact that society expects persons under 18 years of age to need additional supervision and warrant more rehabilitation in the case of crimes. It seems so juvenile that someone who commits a worse crime (and is more in need of rehab) would magically be considered an adult just because of severity. Do actions make someone an adult, or age and experience? EDIT: I think it is also important to consider there is a growing amount of evidence that states adolescence continues up until 25[1]. Also, many cases that have children tried as adults aren't emancipated minors, it's typically just due to severity. I would consider an emancipated minor tried as an adult more logical, but possibly more morally wrong for a society to do. Emancipation isn't generally a happy thing, and often due to poor circumstances... more rehabilitation would likely make sense, but I see how it would be logical for a system. [1] http://www.bbc.com/news/magazine-24173194 _____ > *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)****! If you are thinking about submitting a CMV yourself, please have a look through our* ***[popular topics wiki](http://www.reddit.com/r/changemyview/wiki/populartopics)*** *first. Any questions or concerns? Feel free to* ***[message us](http://www.reddit.com/message/compose?to=/r/changemyview)***. *Happy CMVing!*

The ability to be able to try a juvenile as an adult is an example of taking the law on a case by case basis which is a good thing. In general it is not reasonable to think the law is going to work effectively for every person. If there was a 17 year old serial rapist would you really want them to have their record wiped clean on their 18th birthday?

What do the symbols connecting the elements mean?

http://upload.wikimedia.org/wikipedia/commons/b/bc/Nitrogen-iodide-2D.png In this picture, there are three types of bonds. What should I search for to learn what they mean?

These bonds show the 3 dimensional structure of the molecule. The plain lines are in the plane of the page. The solid wedge shape signifies a bond coming out of the page towards you. The dashed line signifies a bond going into the page away from you. It's as simple as that. Chemists use this to show a 3D structure in a 2D drawing.

CMV: science and religion can perfectly co-exist

I feel like a lot of people think science or religion provide all the answers to a problem, that either of them holds the 'universal truth'. I believe they just provide a different viewpoint. Science will perfectly explain how I'm able to live (how does my heart beat, why is the air breathable, what do I need to eat in order to grow...), while religion might provide me with answers regarding how to live my life or how to find meaning or purpose. I sense a lot of problems arise when trying to find religious answers for scientific issues and vice-versa.

It's not that science and religion can't coexist, it's a question of whether there's good reasons to believe each of them individually. Science is an itterative process that produces tentative conclusions that attempt to predict how the world works from observation and testing. Religion is a mix of subjective claims (like those about morality and purpose) with objective claims (like about whether a god exists). The question isn't whether these can coexist, but whether we have reason to believe either. Saying that can coexist to me sounds like saying that counting and guessing can coexist as ways to see how many cookies there are in a cookie jar.

Introductory books for understanding Kant, Hegel, Marx, Lacan, Zizek, Semiotics, and post-structuralism?

Hi everyone, I have a (very) basic understanding of all of the above, however it is very unstructured and based on bits from here and there. What are your recommendations on books that introduce the above, preferably in an organised sistematic manner? Books that would pave a way for further development by helping to set up a foundation. Of course recommendations of books, courses, podcasts that link two or more of them are very welcomed.

Some general recommendations: *Kant* by Guyer *Hegel* by Beiser *The Philosophy of Marx* by Balibar *The Lacanian Subject* by Bruce Fink *How to Read Lacan* by Zizek *Critical Semiotics* by Genosko *French Philosophy in the Twentieth Century* by Gutting. One could probably list hundreds of more books, but as a start, these will serve you well.

ELI5: Why does Vitamin B have so many variations?

Vitamins are grouped together based on their function within the body. B vitamins are mostly associated with metabolic functions, as well as DNA synthesis. Because of the wide range of different molecules we can metabolize, there are a large group of associated B vitamins compared to other groups.

How did engineers build the Shahara Bridge?

I saw [this photo](http://imgur.com/LmyFZ) of the Sahara Bridge in Yemen. Since this bridge was built quite a while ago, how did they do it?

For arches a wooden form is usually put in place until the stones are properly arranged. Presumably they started with ropes, then a wooden scaffold and form, then removed everything once the arch was in place.

What are the functional differences between a Universal Basic Income, Negative Income Tax, and a Guaranteed Minimum Income?

Sometimes those terms are used interchangeably.. and sometimes each type has different models of how it operates.. But generally, Universal Basic Income is a flat amount granted to every individual regardless of income.. For example, every citizen receives $1000 per month.. With Negative Income Tax people below a certain level get a stipend that is based on a percentage of the difference between a threshold amount and ones income level.. For example, if the threshold amount is $20,000 and someone earns $10,000 and there is a negative income tax rate of 25% that person would get $2500 added to their income.. Guaranteed Minimum income is a lot looser to define and can entail many different kind of strategies. Ultimately there is some kind of minimum level of income identified and only people who qualify in some way receive the benefit/transfer or whatever you want to call it.

[Charlie and the Chocolate Factory] How dangerous was it actually for the Oompa Loompas in Loompaland?

Wonka claims that the reason he took the Oompa Loompas away form their homeland is that Loompaland is full of whangdoodles, hornswogglers and snozzwangers, that would have eventually wiped out the Oompa Loompas. Is that true? Were the Oompa Loompas really that maladapted for life in their own home environment?

There is one important thing to remember when thinking of evolution: You don't need to be the fastest, toughest or strongest, you only need to survive until you get old enough to multiply. Seeing that they are pretty plentiful, they might just have been eeking by by pumping out more small Oompa Loompas than got killed. And for how dangerous it was? *Appearently so dangerous that no one else made it back to tell the tale*

Why aren't bullets cone shaped?

I can't seem to understand why some rounds (eg. [9mm](http://upload.wikimedia.org/wikipedia/commons/9/96/9mmLuger.jpg)) are rounded not cone shaped. Isn't a cone the best shape to pierce air?

Intuitively, it may seem that a cone is the best shape but keep in mind that there are multiple factors in play. One of which is torque. - A blunt object is subject to less destabilizing torque than a pointly one by having the leading edge closer to the center of gravity. - Spin is induced to resist torque. It is easier to spin a cylindrical object on it's axis than a cone shaped one.

[General/Superheroes]Are heroes judged "street class" because of their abilities or feats?

My friend and I were discussing what constitutes a street class superhero. My friend said it was based on their powers, I said it was based on their feats. Then he brought up a good point.....that if they were judged by their feats, then Squirrel Girl is a World/Cosmic class hero..... Thoughts?

It is usually actually based on the scope of their operation. Many heros go from street to world class over the course of their story, few transition in or out of cosmic because of what being a cosmic hero entails. For example, Ben Grimm is a world class hero because he travels all over the world with his friends stopping bad guys. Even in the few cases that he has fought cosmic bad guys (Galactus) he did it to defend the earth. Powerman, who basically has the exact same power set, is street class because he spends his time trying to clean up Hell's Kitchen with Iron Fist and Daredevil. Both of those guys fought Galactus. Silver surfer mostly fights weird space wizards who are really not much more of a threat than your average super villain but they are space wizards who live in space so he is cosmic class.

How does a hard disk create space for new files after deleting old ones but is still capable to recover those deleted files?

As soon as I empty my recycle bin my windows PC tells me, I got now more space to put new files in to. I can even limit out this space. Still with apps like Windows File Recovery I can see files which has been deleted months ago and recover like they were never gone. How is this possible?

The operating system uses a file system which is the schema used to store the files on the disk. Different file systems have different capabilities: file name length, maximum file size, encryption, etc... The general idea behind a file system is that it creates a table somewhere on the disk that it uses like an index for where the data for each file is stored: file 1 is between bits 1 and 100, file 2 is between 1001 and 15,500, and so on. When you delete a file it removes its index entry which, essentially, marks that space as “empty” and can be written on. However, the data is still on the disk, it’s just not accessible (because of the missing index entry). If you can get to the data on the disk before it’s overwritten then you can retrieve it. To securely delete a file, you need to replace the file’s data with other data. Some even say you need to do that multiple times. There’s software that does that if you’re paranoid.

ELI5: Why are there "colleges" for specific majors inside of large universities?

Ex: College of Engineering @ University of X; Also, for undergraduate applications, do you apply to these specific colleges, or the larger one?

The first universities, as we understand the term, came into being when multiple smaller institutions (colleges) joined together under one name, but retained their individual identities and traditions. Oxford, for example, is made up of 38 colleges. They all teach the same stuff, but they all have their own flavor. Kind of like the houses in Harry Potter. In the modern day, colleges aren't for individual majors, they're for groups of disciplines. The college of social sciences, for example, would include the departments of psychology, sociology, and communications. The college of physical sciences would include physics, chemistry, and astronomy, and so on. They organize this way for a number of reasons: Tradition, because some classes don't fall neatly under one major, and because it facilitates fundraising--a super-rich surgeon might want his donation going directly to the departments whose classes he took. Hence the Bill Q Moneybags School of Business, or whatever. To answer your question, generally you apply to the university, then select the college if they make you choose (not all do).

What is the difference between an aeroplanes 'air speed' and its 'ground speed'?

The wind. The airspeed measures how fast the aircraft is moving with respect to the air. This is an important piece of information since the dynamics of flight depend on the speed of the aircraft with respect to the air. For example, the amount of lift generated by the wings depends on the airspeed. The groundspeed is the speed of the aircraft with respect to the ground. This determines how fast the aircraft makes it to its destination and for passengers, the groundspeed will be the only relevant speed measurement. If there is no wind, the airspeed and groundspeed are equal. If the airplane is experiencing a headwind, it's airspeed will be higher than the groundspeed and vice versa for tailwind. To make life more complicated, there are multiple versions of the "airspeed", because what the pilot reads on his instruments is not necessarily the true airspeed. Corrections have to be made for calibration error of the instrument, compressibility of the air, etc...

[Star Wars] How is it possible to blockade a planet without an Interdictor type vessel?

Naboo: What kept ships from escaping perpendicularly from the blockade? Or even the other side of the planet. To make a ring of ships around a planet with intersecting lines of fire would take an enormous amount of ships. To make the blockade spherical is unthinkable. AFAIK the Trade Federation did not have Interdictor technology.

I don't know a lot about how space travel works in Star Wars but there might be certain "angles of approach" or something similar that ships entering the planet have to take to land safely and it's much easier to cover those areas of orbit. That is just me speculating though

What does Sartre in "Being and Nothingness" mean when he says that reducing an existence to its manifestations is not succeeding in overcoming all dualisms but instead converting them into a new dualism of finite and infinite?

There are infinite ways in which something can manifest itself within consciousness, but it can only be experienced one mode or way at a time. An egg is the source of an infinite number of experiences, but it can only give me one side of itself at a time.

CMV: Chipotle should not be directly blamed for their viral outbreaks

Please note that I frequently eat Chipotle so I do not have an objective view. I don't think we can blame chipotle for these viral outbreaks. Yes, it happened, and yes there are some terrible side effects. These things happen, and we should be judging chipotle based on their response and action to the outbreaks. So to my knowledge, there were three outbreaks: Norovirus, E Coli, and Salmonella. Norovirus was given by two employees (in two locations) that had Norovirus, but still chose to work anyways. This is definitely not Chipotle's fault. Obviously, if you're feeling the full effects of an illness, you should be prevent from working at a restaurant. However, many contagious viruses lie dormant, or the symptoms start very small. Some continue to linger even after symptoms disappear. For example, let's say an employee had Norovirus for 2 days, and he's not feeling the effects of it yet. He feels perfectly fine, maybe a bit uncomfortable, but no symptoms at all. Nothing out of the ordinary, and nothing to say "you shouldn't go to work today." Boom, suddenly people are infected with Norovirus. It's that easy. And it's not Chipotle's fault. No company has a policy to get you tested for viruses every day. People get viruses without realizing, and spread them without realizing. It happens. Salmonella and E.Coli are a bit more difficult. They're hard to track, especially if a tiny portion of an order was infected. Even the CDC has difficulty tracking the origin of these viruses because of the massive quantity. Chipotle definitely has controls that check the quality of the products. However, it is impossible to check every individual product. They check a sample or two, or use a machine to check batches, etc. Even with that, the chances of preventing these viruses may only be 99.99%, never 100%. So in the rare case that EVERYTHING goes perfectly, but it still slips through the cracks, that's when an outbreak happens. It's incredibly unfortunate but we can't assume that Chipotle had faulty controls, only that their controls did not detect the issue. It's analogous to say, surgery. Even if you do the process perfectly and had the best doctor in the world, a person can still die even with the simplest surgery. It's unlikely but it happens. _____ > *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)****! If you are thinking about submitting a CMV yourself, please have a look through our* ***[popular topics wiki](http://www.reddit.com/r/changemyview/wiki/populartopics)*** *first. Any questions or concerns? Feel free to* ***[message us](http://www.reddit.com/message/compose?to=/r/changemyview)***. *Happy CMVing!*

E. coli and Salmonella can be combatted by proper food handling, storage, and preparation techniques. It's likely that the cause of those outbreaks comes down to improper food preparation. For example, under cooking the meat, or not properly cleaning surfaces that touch raw meat, etc.

CMV: "Human sexuality is binary by design with the purpose being the reproduction of our species. This principle is self-evident.”

Hi folks, a biochemist here. The quote in my title represents my view about human biological sex - that humans are a binary species. The fact that conditions like Klinefelter/Turner exist doesn't imply the existence of other sexes, they're simply genetic variations of a binary system. The idea that sex is not binary is an ideological position, not one based in science, and represents a dangerous trend - one in which objective scientific truth is discarded in favour of opinion and individual perception. Apparently scientific truth isn't determined by extensive research and peer-review; it's simply whatever you do or don't agree with. This isn't a transphobic position, it's simply one that holds respect for science, even when science uncovers objective truths that make people uncomfortable or doesn't fit with their ideologies. So, CMV: Show me science (not opinion) that suggests our current model of human biological sex is incorrect. ​ EDIT: So I've been reading the comments, and "design" is a bad choice of words. I'm not implying intelligent design, and I think "Human sexuality is binary by \*evolution\*" would have been a better description.

How can there be variations of a binary system and that doesn't invalidate the idea that it is binary? It's like literally 'there's exactly two, except for those others, which are variations on the two' At the very least the existence of XXY, XYY, XYYY, XXX, XXYY, XXYYY, X0, etc. would make it bimodal, not binary Edit: please stop replying to this comment and telling me that some human beings are "errors" or "mistakes" or "genetically inferior". It is really not a good look

ELI5: How does an internet connection become slow?

Lots of things can have an effect. If many people in your home are using the same WiFi network, the network may become bogged down. Interference can seriously degrade your signal, if there are any big sources of interference between you and the router. Walls, floors, etc can have an effect on wireless signal too. A wired OR wireless connection may be throttled by your provider or slowed down if there is a lot of internet traffic in your area. Outdated modems/routers or damaged equipment (modem, router, Ethernet cables, antennae, cable in the ground) will certainly not help.

Could it ever be possible to invent a bionic eye that allows people to see light outside of the visible spectrum, such as ultraviolet or infrared?

Your brain could probably handle the input anyway, experiments have shown that mice and new world monkeys are capable of comprehending the difference between red and green after having their natural red-green colorblindness fixed by gene therapy.

Does this study imply that people will live longer if they worked out *without* taking (much) protein?

Long-term low-protein, low-calorie diet and endurance exercise modulate metabolic factors associated with cancer risk1,2,3 http://ajcn.nutrition.org/content/84/6/1456.short

I think the answers you are looking for are at the end of the paper. The authors say: > In conclusion, our data show that the consumption of a low-protein, low-calorie diet; exercise training; and decreased adiposity are associated with low plasma insulin, C-peptide, FAI, leptin, and C-reactive protein and high SHBG concentrations, which are circulating factors linked with some types of cancer. High concentrations of those factors (except lower for SBGH) are associated with different types of cancers. This doesn't necessarily mean that high concentrations of these factors cause cancer. It means when you find certain types of cancer, you are likely to find high concentrations of some of these factors too. Their experiments showed that 3 things: exercise, a low protein/calorie diet, and low adiposity, are all associated with lower concentrations of these factors (and higher SBGH). This, again, doesn't necessarily mean that lower levels of these factors (and higher SBGH) will lead to a reduced cancer risk. But, as the authors say: > These results help to identify potential mechanisms by which long-term lifestyle modifications in diet or physical activity can selectively reduce circulating factors that are associated with increased cancer risk. This idea has yet to be proven and the association observed in this study is only shown with 21 people. And unfortunately, it would be difficult to try to provide proof for this idea: > A long-term randomized controlled trial would be needed to determine cause-and-effect relations. It seems that this was a relatively small but practical study that looked at the associations between several cancer-related factors and diet/exercise that may prepare the way for more investigation into this potential relationship.

Are terrastrial and marine food chains disconnected? If they are connected, how and to what degree?

Does plankton end up in a cow living on a farm on a macroscopic scale? How about a terrastrial apex predator living hundreds, if not thousands of miles away from the closesr ocean? Is bottom of their food chain in the ocean? Is there research about this topic? I can not imagine them being disconnected, and I would really like to know how e.g. nutrients and vitamins end up from the ocean to our food plate (in form of terrastrial plants or meat).

They are definitely connected in many areas, though not in the way you think. The annual migration of Salmon up rivers to spawn plays a significant role in the forest ecosystems, moving nutrients and minerals into areas that would not otherwise have it. Given that some salmon swim well over a thousand km up the rivers, this effect goes deep inland. This effect is mostly occurs through the actions of bears and wolves, the apex predators. They catch the salmon, haul them to shore, eat part of them, and the rest of the carcass rots away. Similarly, after they spawn and die, the carcasses of the dead fish wash ashore and have an effect. Going the other way also has a dramatic interconnection as well. Nutrients and other materials wash into the sea, which feeds plankton and algae, which is the bottom of the food chain. The salmon (and other fish) eat this, thus keeping the cycle going.

Why is reason so compelling?

This was a question my Epistemology professor and I were discussing. unfortunately we never resolved the question. So maybe you fine philosophers here could help. It seems axiomatic that reason is the mode by which we arrive at the truth, but how is it and why is it the means by which we arrive at the truth? I used to just accept, there are no other useful alternatives, but that just raises the question: Is reason compelling because it's useful? And if that is the case than reason won't necessarily always arrive at the truth. If anyone also knows any literature on this subject I'd be very grateful.

Schopenhauer provides the counsel of despair: Reason is compelling because we appeals to the cognitive apparatus by which we understand experience. In a way, that's an inversion of the medieval conception of *adequatio*. We are not privileged by our capacity for understanding a reasoning that independently describes truth; rather, reason is adequate to our capacity for cognizing the world, which means that reason is a human constraint on knowledge. That's a counsel of despair because it provides, at the very same time, an explanation and a limit. If sufficient reason is just how we cognize experience, then there's no guarantee that it points us to the truth.

I am considering going to grad school for philosophy

I am considering going to graduate school for philosophy. I have my Bachelor’s in math, which, as a career, would seem to offer fine job prospects, but I really don’t care much about mathematical problems. I like the argumentation aspect, writing proofs, etc., even though it was mainly an applied math school and that element wasn’t emphasized as much. Even so, I have been doing independent study and have been getting tutored by one of my former professors in some abstract algebra stuff bc it was what I was most interested in, and I still really don’t see myself doing this. I have always wanted to study philosophy. I think about philosophical problems most of the day, and I feel my brain is “wired” for it. I love argumentation, working with concepts, and I am pretty open to reading and thoughtfully considering a diverse range of perspectives on any topic of interest, from both the analytic or continental traditions. Some concerns I have are: 1. Getting and keeping jobs 2. Having social anxiety and OCD (relevantly, with existential, perfectionism, and religious themes). I have been through therapy for this and am on medication, albeit I am still figuring the latter part out. I would say that I find myself thinking on philosophical topics not as a compulsion anymore but because I genuinely like it. Still, I do have a bit of concern over this— that it might be a triggering situation for this to become my career path. On the other hand, maybe that’s a good thing. And it was, in some ways, a form of philosophical boot camp. And as for social anxiety, that’s much better too, but it rears its head again every once and a while, especially in public speaking settings. 3. My bachelor’s is not in philosophy, albeit mathematics is not unrelated to philosophy (through it I have experience with logic including symbolic logic). However, my primary areas of interest concern human endeavors (i.e. ethics, aesthetics, action theory, free will, philosophy of psychology, philosophy of religion, philosophy of language, mainly). I would say philosophy of mathematics, logic, and other math-adjacent areas do interest me as well, but not as much as the others and more to the extent that they have implications for the fields previously mentioned. Any considerations I should have when looking into studying philosophy in grad school? Any advice on applying for schools, especially as a math major? “Don’t do it” is also welcome advice, provided you be sufficiently specific.

Have you thought about how the social anxiety stuff may affect things like presenting in seminar, doing oral defenses, giving talks, and then later teaching and doing team work with colleagues? You wouldn’t be the first socially anxious phil student, but there can be rather a lot of public speaking and high stakes performance.

ELI5: Why does the virginity of oil matter?

The amount of benefits that first pressings give are much higher than subsequent pressings as far as nutrients, and anti-oxidants goes. Only so many to go around and the first press gets the majority of them.

CMV: The solution to (future) student debt is not to make the colleges free, but to make them more efficient.

I am seeing a lot of posts and news articles recently about lowering the student debt, most notably Bernie Sanders claim to make all colleges free. The debate seems to rage back and forth about whether this is tenable, and who would pay the cost, but for me, this seems to be totally the wrong direction. When I went to university, out of the four years getting a psychology degree, I learned maybe 2 years of psychology. The rest of my courses were electives. In fact, I took as many psych courses as they would allow, getting special permission to specialize, and it was still less than half. Upon graduating, I found out that most masters programs don't require you to have your bachelors in their subject, as they are basically teaching you from scratch (some will add one extra year if you are from a totally different discipline). Why can't the solution to be to push for less extraneous courses in college? It would lower the debt (less years) and allow you to join the workforce earlier. Prime examples: Law school can be entered with any degree, Medical school requires a single years worth of prerequisite sciences and any degree, Masters of psychology can be done with any degree, Computer science Masters will require only 1 additional year if you have no background... I feel like I am missing something obvious here. Please CMV. _____ > *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)****! If you are thinking about submitting a CMV yourself, please have a look through our* ***[popular topics wiki](http://www.reddit.com/r/changemyview/wiki/populartopics)*** *first. Any questions or concerns? Feel free to* ***[message us](http://www.reddit.com/message/compose?to=/r/changemyview)***. *Happy CMVing!*

Colleges have an interest in their alumni being generally well educated in a variety of subjects. Smart, successful people usually aren't hyper-specialized - rather, they are knowledgeable on many subjects, and can recognize important relationships between subjects in order to find success where others haven't. Successful people who are alumni of a certain school reflect well on that school, and may even donate money to their alma mater. Teaching people in a hyper-specialized manner is good for getting them out the door to be a grunt in the workforce, but it probably isn't going to make many really successful people. Nobody remembers how many grunts a college is churning out - people remember the particularly successful people.

How were archeological and paleontological artifacts dated before the "radio-carbon revolution"?

What methods did scientists use to estimate the age of artifacts before the advent of radio-carbon dating methods? I've read that radio-carbon dating led to a "revolution" in archeology, paleontology, and anthropology (probably geology as well, right?), but I'm totally ignorant about what methods were used before carbon dating, and if any of those methods are still in use today. Thank you!

A lot of dating came from and still comes from stratification methods. Essentially, the deeper something is, the older it is. As you dig down you can usually see layers of dirt. Each layer corresponds to a different time frame, thicker layers usually mean longer periods of time. Edit: Though this isn't always true. A landslide could deposit a lot of dirt in a short time. For example, when the asteroid that hit earth leading to the deaths of dinosaurs occurred it sent up a lot of dust/dirt into the atmosphere. Over the course of a few decades, that dust fell back down, coating the entire earth with a thin layer of black dust (laced with asteroid elements!). With archaeology it's about the same thing. Maybe in the top layer the scientist finds a roman coin that has a date on it. So they know that particular layer of dirt is at least X years old. The next layer they find a pot that references an emperor a that was born 700 years before the coin's date. Now they know the pot is older than the coin (because it was deeper), but younger than the emperor that was referenced. The next layer they may find a bronze tool. They know that the bronze tool is older than the pot because it's deeper. If the coin is 500 years old, the pot is at least 500 years old, but no more than 700 years old, the tool then is probably older than 700 years. Done enough times over a wide enough area the researchers can get a pretty good idea of relative ages of things. Eventually, with enough data points, they would be able to say, "The coin is exactly 500 years old because it has a date, the pots were made until the death of the emperor they depict, so it's between 700 and 670 years old, and the bronze tools have been found at settlements that date back to 800 years ago, so the tool is between 700 to 800 years old." They still do this often for geology and archaeology too.

How do you forecast wind? I understand being able to forecast things like rain, snow, and sunny days based on cloud formations? But how can someone determine if a day in the future will be windy, and how strong that wind will be?

Weather forecasting actually \*starts\* with figuring out the winds: you need to know how hot and cold air and humidity are moved around by the wind before you can forecast temperature and rainfall. It all starts with Newton's second law of motion "F=m\*a", and estimating the forces on any given mass of air to find out how it accelerates. Air pressure, gravity, and friction are the most important forces, but the fact that the Earth is rotating plays a key role too. As the forces move the air around, the temperature and pressure change, so it's a pretty complicated set of interacting equations. In the vertical direction, there's usually a balance between air pressure forces and gravity which we call "hydrostatic balance". In the horizontal direction, usually air pressure balances against "Coriolis forces" caused by Earth's rotation. This is called "geostrophic balance". Geostrophic balance causes the wind to go in a circular motion, orbiting around regions of high and low pressure. But to go beyond this, to find out how those high and low pressure regions change over time and actually predict the weather, you really need a computer. I hope that's a satisfying enough answer: to get into more detail than this, unfortunately you need at least a couple years of preparation in calculus and physics to understand the equations. It's not an easy problem!

ELI5: What made us, so many years ago, just being naked be seen as being indecent?

While clothing began as a "tool" to keep us warm, it quickly developed a symbolic meaning far beyond this. For example, it distinguished tribes/groups/nations from one another and indicated social status, wealth, and personality. It still does this. In a society that developed cultural norms such as sexual restraint, monogamy, and other sexually normative social pressures, clothing became representative of these cultural factors. To not wear clothing was, in essence, to communicate a sexuality that was taboo. Clothing as seen by the anthropologist is simply an outer representation of cultural beliefs. If a society believes in sexual restraint - taught by religions both modern an ancient but also common in non-religious societies (e.g. modern China) - then the clothing will represent these cultural norms. So in short, clothing became an expression of modesty and social pressures to conform and be accepted.

[General "Hard-ish" SciFi] Wouldn't missiles be relatively useless in a space battle, considering the potency of future detection systems associated with laser point defense systems?

Considering Issac Arthur's "First Rule of Warfare" (there is no stealth in Space) and considering that missiles can never beat lasers for speed, I don't see how missiles could be used in space warfare, if we are talking about a relatively hard scifi story. Is there something I'm not considering?

Depends on a lot of factors, including the relative sophistication of the missile and related technologies. In the most general sense a missile in the sense of a *kinetic projectile* has a lot of utility behind it: Force equals mass times acceleration, so even a little mass moving really fast (*a la* a rail gun or thor shot) can pack a lot of force, and lasers or other energy weapons might not be able to boil enough of that mass off fast enough to prevent impact. If you're talking about missiles in the sense of self-propelled munitions, it's a little more difficult. Again, the whole point is for your missile to get close enough to the target to do some damage, and point defense systems can put a crimp in that...but for every countermeasure, there are counter-counter measures. Exotic materials or construction that make it hard to target, ablative armor that can absorb enough "hits" from point defense but still get through, or swarming the target with more missiles than the point defense can handle...all solid possibilities.

If the active ingredient in Marijuana is THC, why are there different effects depending on the different strains? Are there more chemicals at play here?

Is this psychosomatic because of the different levels of THC or is there actually more to it? People say they react differently with hard alcohols but that's more in their head. I'm wondering if that's the same with strains of pot.

There are as many as 85 active compounds in marijuana, THC happens to be present in the highest concentrations and THC levels are used to measure potency. The effects of many of the other compounds aren't well understood. (www.ncbi.nlm.nih.gov/pubmed/23386598)

ELI5: Why does cat nip effect cats like it does, but not dogs or other animals?

Thanks for the help, I've always been curious.

Terms to know: Nepetalactone - a compound in catnip / Olfactory system - the sensory system used for smell In short, researchers are really unsure what exactly causes the cats to go into a craze like they do, thus they can't figure out why dogs / other animals aren't so easily affected by it. There isn't really an answer to this, however, here's a little information on what happens. From what researchers can grasp onto.. Inside of catnip there is nepetalactone, which is known to be a very strong compound. The way that this compound effects cats is that it gets into the cats noses and to where the olfactory system is, the nepetalactone binds to the receptors inside of the olfactory system and triggers signals to the brain. Researchers aren't quite sure why exactly cats react to it as they do, they suspect that it pretty much mimics cats "happy" pheromones and cause a reaction in their brains that is the same reaction that comes from those "happy" pheromones. For measure on how strong catnip is-- researchers say that the compound nepetalactone is up to TEN times more effective at repelling insects than the most commonly used compound in insect repellents. So imagine all that strength inside of the cats little nosies? Crazy, right?

ELI5: we already know how photosynthesis is done ; so why cant we creat “artificial plants” that take CO2 and gives O2 and energy in exchange?

Artificial photosynthesis actually is a deeply studied field of research, where you use sunlight to drive a reaction that releases oxygen from various solutions. The problem is, the components needed in the reaction are inefficient, degrade/deplete quickly, or are expensive to make/maintain.

I've read a lot of speculation about the future of the world's water supply. How serious is the issue, and what is likely to occur over the next decades?

The main thing to remember about this is the interconnectedness of resources in general. There's plenty of water in the world; it's just not potable. The availability of cheap energy would solve this issue, as that's mainly what makes it expensive to, say, desalinate seawater.

Would paddling a canoe work if water had no viscosity?

Viscosity is the frictional force internal to a fluid. What would happen if one was paddling a canoe in a fluid with 0 viscosity? Would it just be the equivalent of throwing water molecules through a vacuum?

There are forces at work here other than fluid to fluid drag (viscosity). As you're swinging the paddle through the water, each water molecule in its path needs to somehow get on the other side of the paddle. Since the water has mass, and thus inertia, moving around the paddle requires some force. Specifically, getting out of the way of the way of the paddle requires positive pressure (to push the water out of the way), and filling the void behind the moving paddle requires negative pressure. None of these processes require viscosity to operate. It's similar to the heating of the air in front of a space capsule entering the atmosphere, where the heating is not due to friction in the air as much as the air's inability to get out of the way fast enough.

ELI5: What is the attorney-client privilege and when is it disregarded?

Attorney-client privilege is a privilege - a protection allowed under law, that protects communication between an attorney and their client and prevents them from being forced to testify. This allows attorneys to do their job and be able to properly defend their client. It's very hard to come up with a good defense if your lawyer can't discuss the elements of the case with you. There are ways that the privilege can be broken. If a third party is present, there can't be privileged (note co-counsel or other agents of the attorney don't count) and the attorney cannot use privilege to cover up crimes unrelated to the case at hand.

ELI5: In quantum mechanics, what do they mean when they say a particle takes "every possible path"?

I'm referring to Feynman's sum of all paths, which is often mentioned in layman physics books but rarely fully explained. What counts as a "possible path"? Often it is described as a particle travelling from point A to B could include a path in which it heads off to Alpha Centauri and back again. I know quantum physics is very counter intuitive, but in what way are we supposed to picture the particle heading off to Alpha Centauri? What sent it in that direction? What would have caused it to return? And are we assuming it travels below light speed (in which case that path would take years) or does this it not matter if it moves faster than light since this path is not the actual one measured, but only incorporated mathematically (whatever that means)? In that case can we take it to the extreme and say the particle also took a path to the other side of the observable universe and back again?

A basic difference between classical physics and quantum theory is the fact that within the quantum world, certain predictions can only be made in terms of probabilities. As an example, take the question whether or not a particle that starts at the time A at the location A, will reach location B at the later time B. In classical physics, an answer can be given depending on the particles velocity and the forces acting upon it, giving a simple yes or no answer. BUT, In quantum theory, it is only possible to give the probability that the particle in question can be detected at location B at time B. Quantum mechanics therefore considers all possibilities for the particle travelling from A to B. Not only the boring straight-line approach, but also the possibility of the particle turning loopings and making detours etc.

ELI5: How does a graveyard stay in business after it's full?

Even after a cemetery is full there are still maintenance costs for things like landscaping and security. Cemeteries have a few ways to keep paying those fees. In many states in the United States, cemeteries have to set aside a portion of each purchase for a perpetual trust. The interest earned on that trust is supposed to be enough to continue operating the cemetery once it fills up. In some places like Germany graves are leased for about 20 years or so. After 20 years if no one renews the lease the headstone is removed and the grave becomes open to a new occupant. Under this system cemeteries are always making sales because graves either open up or get re-leased. In some places like England they go for double decker graveyards. Some cemeteries will dig a grave deeper so that another coffin can be fit above while still buried. Not every cemetery is financially successful. What happens when a cemetery goes bankrupt is pretty highly dependent on the specific situation and applicable laws.

Interview questions for faculty position?

If any of you serve on hiring committees, can you help a sister out and share some of the more commonly-asked questions when you interview people for full-time faculty positions? The only "real interview" for a faculty position that I've ever had was a phone interview with a hiring committee, and I can't remember any questions they asked off the top of my head. If it helps, I would be teaching biology and public health courses if I was hired by this particular school. Thanks!

These are slightly edited questions we've asked on skype for an instructor position. When you are face to face you should also feel comfortable repeating answers from one person to the next (they don't compare exact notes so it's not like it's "cheating" to re-use your good answer to professor 1 with the same question from professor 4). You'll also be surprised how many of the professors will treat this as an opportunity to talk about their favorite subject: themselves. (e.g., "you must have talked about yourself a lot, what questions do you have about ME"?) • Why are you interested in a faculty position (Instructor, 9 month) at the University of X? How could this opportunity help you achieve longer-term career goals? • What courses would you like to teach in the XX program? Why? • What are your plans to optimize your effectiveness as a teacher? • Since this is a 9 month teaching position, what opportunities would you want to pursue during the summer months? • Describe your teaching and mentoring experiences, particularly with undergraduates. What motivates you to be a good teacher? There are similar questions if you would be doing research - where would you get funding from, who would you collaborate with, where do you see your program in 5 years, what experience do you have in proposal writing or project management. Good luck!