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If the universe is accelerating, and life that will exist 100 billion years from now cannot detect things that occur in the universe today, can we detect things that happened 13 billion years ago? Would they not have just disappeared? [Details Inside]

According to the ending of this video (http://www.youtube.com/watch?v=EjaGktVQdNg), Lawrence Krauss states that the universe will continue to expand in such a rate that the life on a galaxy 100 billion years from now will only see itself and will be alone. The information that they gather about the history of the universe will be false. Today, the universe is 13.7 billion years old. Can we confidently state that we know the state of the universe 13 billion years ago? Would certain aspects of the universe's creation be possible 'extinct' in time?

The word "seeing" has two meanings here, to see as to literally receive visible light or other EM radiation from objects in the sky, and to be eventually updated on their "current" state. Consider some remote galaxy, the light that it emitted 13 billion years ago is just reaching us. What happens to the light it emitted one year later? Due to the expansion of the universe it's as if the galaxy were rapidly moving away, so the light it emitted exactly one year later would have to cross 13 billion light years plus whatever distance it moved away during that year (or, actually, all additional space that appeared between us) so would take much longer time to reach us, we will be receiving its year's worth of light over the course of hundreds of years (so it's also very weak and red-shifted). The interesting thing about the whole deal is that that galaxy probably has crossed the event horizon of the observable universe, say, 12 billion years ago: no light that it emitted later could outrace the expansion of the space between us. So we will never "see" that galaxy in its "current" state, like, being 13 billion years old. However, we will never stop seeing the light it emitted during the billion years of its lifetime before it crossed the event horizon. It will become more and more diluted, so to speak: weaker and redder, as there's a finite amount of it that has to be spread over infinite time, but it will never just wink out of existence, it will gradually go below the level of ambient noise/our detection capabilities instead.

ELI5: How do we know where to search for precious metals? How do we know that 100 ft underneath my yard isn't the largest gold deposit in the world?

Certain rock types are more likely to have certain minerals than others, but for the most part they look around where they found some precious metals and hope there is more. Lot's of guesswork, gambling, and sampling. Maybe you find nothing, maybe you strike it rich.

Why does fractional banking not cause inflation but the govt printing an equivalent amount of money does?

It does affect inflation - the primary purpose of raising interest rates is to reduce the amount of money created by banks. The banking system creates money through lending, higher interest rates reduces demand for loans, therefore less money created.

CMV: Kids should watch cartoons in a foreign language so they can learn it without effort.

I am part of a minority in my country, which means that my native language is not the official one. However, you do have a right to an education in your native language. So from kindergarten to university, you are taught all the subjects in your own language, if you want to. The only caveat is that the official language of the country is not being taught as a foreign language, everyone has to study the same material and take the same tests at the end of the year. Usually, kids who grew up in cities have an easy time adjusting to this requirement as they grew up using both languages at least to some extent (they tend to have a more mixed population while rural areas tend to be either or). In contrast, those in rural villages have a really hard time when they eventually come to the city for school as they lived their entire lives never having to use the other language. I had classmates in high school who could barely introduce themselves using the official language, let alone conduct literary analysis on a novel written 150 years ago. Sadly it was basically impossible for them to catch up. I grew up in a small town, but we lived in a bad neighborhood so I was never allowed to just hang out with the other kids. Therefore, I met all my friends in kindergarten (and later school), Sunday school, or through my parent’s friends who all spoke the same language. However, the cartoon channels on tv were in the official language, so that’s what I grew up watching. By the time I went to school I understood mostly everything and by middle school, I was pretty much fluent even though I basically never had to use the language. In high school, I was scoring better on tests than native speakers and I don’t remember ever having to actively learn the language. Although, I will say that my accent never went completely away. Therefore, I think children should be watching cartoons in a foreign language because they will pick up on it fairly easily. Also, it doesn’t matter if only one language is used in their country or if they speak the native language. For example, a child from Germany could watch cartoons in English. I think ideally the parents (or someone else the child interacts with at least semi-regularly) would also speak the language so they can ask questions or get familiarized with it in other contexts as well. However, I don’t consider it a requirement as even if the child won’t learn the language perfectly on their own, it will be familiar enough that they’ll have a huge head start once they start learning it in school.

Gaining familiarity with a language at a young age doesn't mean you can learn it without effort. It can complement formal or informal learning, but the effect will vary widely depending on the kid, and in the best of cases will be just a marginal help. So, at the end it's basically a gamble, and you still have to have them learn the language through other methods.

ELI5: Why haven't we been able to develop drugs that don't harm us?

There are a lot of things in life that make us happy; however, drugs can stimulate this feeling to reach a peak. Why haven't we been able to develop drugs like MDMA and cocaine that don't harm our bodies? Is it just not scientifically possible?

Drugs only have effects by making our bodies release or decrease chemicals that we already use on a daily basis. The problem is when you start messing with our natural systems it causes them to change. So for MDMA and cocaine they cause massive releases of chemicals in our brain that give us the stimulated euphoric feeling. The problem is they release so much that our bodies try to compensate by reducing out response to these drugs. After a while our bodies are so "turned down" that out normal day to day levels aren't enough and it becomes very difficult to feel good or even to feel normal without the massive doses the drugs are giving you. After time even the large releases from the drugs aren't enough and you have to take more and more. Drugs themselves are not necessarily dangerous but the problem come from changing the way our bodies function. So no there is not really a way to make a drug that will not alter out body chemistry.

Why are immigrant farm workers well paid in the US but in Mexico they are low paid and food costs about the same in both places?

I live in an agricultural area in the US and we have a lot of farm workers here who are either on visa or undocumented and they earn pretty good money. I'm not saying the make great money but at least $100 a day easily. I recently went to Mexico City and saw that food prices were pretty similar. Some items were a bit more, others were a bit less, give or take 20% or 30% difference. Some places like our version of Whole Foods were of course more expensive but even small food markets weren't that cheap. Stuff that was a bit more "processed" like canned or bottled stuff was actually quite expensive. Anyways I later found out that farm workers there earn around $200 Mexican pesos which is around $10 a day. What I don't understand is how can it be that their pay be that much higher in the US. I have also noticed that this is the case in other lower income places. Farm workers earn less but food is around the same price as the US. Is it that our efficiencies are much better here in the US so one worker produces more at the end of the day. Mexico probably has less machinery, probably uses more water would that be something to consider?

Productivity in the US is higher and workers are paid close to their marginal productivity of labor in competitive labor markets as economic theory says. The US has higher productivity due to a higher level of capital per worker and likely greater adoption of more sophisticated technology as well. Simply by moving across borders, a worker in a poor country can see their productivity and income increase several fold. See "Trillion Dollar Bills on the Sidewalk" in the Journal of Economic Perspectives. It can be found on google

Should I Major in Economics if I Just Want a Bachelor's Degree?

I'm a sophomore in college and might major in Economics (BA). I've read online that those with just a Bachelors in Economics don't get paid, on average, that high. If that's the case, are there chances that someone with a Bachelors in Economics can get paid $90,000 or more? On the other hand, others have told me that an Economics degree is one of the most unemployed majors. If I'm interested in studying Economics then should I major in it or major in something else (if the negatives are true)?

Supplement your economics major with either statistics or computer science and learn to code. Economics will teach you how to think about problems, stats or comp sci-fi will give you the tools to solve them. Very employable combo right there

ELI5 - How do "clearing throats" actually clears our throats?

Im currently down on a fever and my throat hurts so i keep coughing it out. How does it actually helps my throat feels better?

Phlegm/mucus is normally a layer of protection in our lungs and breathing tubes, but when we are ill our bodies often produce too much of it. It can then collect in the throat around the vocal cords which are the tiny folds of tissue that vibrate together when we speak or sing. Coughing or throat clearing is basically slamming the vocal cords together so they push the excess mucus away and back up into the mouth so it can be either spat out or swallowed down and got rid of using our stomach juices. So it generally feels good to get rid of it, but unfortunately until we get better, more mucus quickly arrives to take its place and that's why we keep on coughing.

[The Elder Scrolls] What approximately is the average lifespan in Tamriel?

I'm trying to figure out how the restoration school of magic affects overall health, so I'm only talking about people who die of natural causes.

It's hard to say, because each race has its own particular life span on average, and then you have many great wizards or otherwise remarkable people who outlive that average by quite a great deal. However, the Imperial Census reports that, on average, citizens of each race live to be about: Beast Races - 60 years Human Races (Nords, Imperials, Redguards) - Average for humans. What is it nowadays, 78 years? Orsimer - 80 years (they have the ability to live longer, but since they desire a warrior's death, they purposefully seek death while still "young" and able-bodied) Bretons - Since they are gifted with magic, their life is extended to about 100 years. Bosmer and Dunmer - 150-200 years. Altmer - 300 years Great Telvanni Wizards and the like (usually Dunmer) - Hundreds and hundreds of years Dwemer - ??? Restoration does play a small part in extended the life span of warriors, but there are no restoration spells which truly prevent death. While basic diseases may be cured, and wounds may be tended, there are no spells or potions for terminal diseases or for old age itself. You need to be an incredibly powerful wizard for the essence of magicka itself to bestow life-prolonging properties upon you.

ELI5: How are athletes with different disabilities sorted to compete against each other for the Paralympics?

The International Paralympic Committee (IPC) publishes a handbook that establishes the different levels of disability. There are a ton of categories. Swimming, for instance, has 15 different categories, ranging from S1 "very severe coordination problems in four limbs or have no use of their legs, trunk, hands and minimal use of their shoulders only," up to S15 which is for athletes who have hearing loss (but have full function of their limbs) Athletes are classified by their country's Paralympic body as per the IPC regulations.

[Harry Potter] Why did Snape never go public with his potion refinements?

It seems like he could have possibly made himself some good money if he'd sold his updated recipes from the Prince's Potions book to the textbook makers, so why didn't he?

They were improvements to a high school text book. Your high-school science book was oversimplified to the point of being wrong. (electrons aren't tiny little balls that orbit the nucleus in neat circles, for instance). Perhaps every master potion maker already knows these improvements and more.

CMV:Being a loyal voter to a party makes a less valuable voter.

For the sake of example, imagine a country with 2 parties, A and B, and that a person X is a loyal voter to A, meaning in 90% of the cases he will vote A. If A is in power, they won't need do a lot to make sure that X votes A. I mean, what will he do? Vote B? If B is in power, it would take them a lot of effort for them to convince X to vote for B. Incidentally, spending too much effort on pleasing X might lose them their own support, which fracture the party and weaken it. In this case, the most valuable voters are those who are flexible with their loyalties. EDIT: By valuable, I mean someone for whom both parties would spend some effort to attract. Valuable to the party. EDIT: for ease, person Y is a swing voter. EDIT: I have read through the comments, and I realize that my model was too simple and applied to only a few cases. I made some assumptions, like high and static voter turn-out. So my V is C'ed. _____ > *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!*

1. Voters do consider other voters' votes, and there, loyal voters have tremendous value. Consider candidates A, B, and C in a primary, and A's loyal voters are around 50%. Will the other candidates even run in this situation? 2. Same things happen in the general election, but this time with states. This time, let's have your example with parties A and B. In a state whose majority has always voted for party A, would party B even spend money? 3. Having loyal voters have tremendous value during campaign periods, having an established base of support matters a lot in terms of raising funds.

[Physics] Do fields actually exist?

Take the electromagnetic field, for instance. Photons are quantized, meaning that it takes a threshold energy level for the photon to even exist. On the other hand, photons are excitations of the electromagnetic field. Putting these two ideas crudely together: if there's no photon, then that means *there's no excitation in the field*. So if that is true, then how could you distinguish the field from nothingness? To put it differently, do fields exist independently from their particles?

> To put it differently, do fields exist independently from their particles? Yes, fields are much more fundamental. There are QFTs where there are no "particle-like" excitations, so even though there are excited field configurations there is nothing resembling a "particle" in these theories. Also, there can exist field configurations which do not have particles in them even for electromagnetism. A static electric or magnetic field - like say a Coulomb field - does not have any photons in it, but it's a nontrivial configuration of the field. In other words, particles are just particular kinds of excitations in fields, but they're not the only possible excitation.

How significantly do plastic dental appliances, things like retainers, Invisalign, or night guards, contribute to the build up of microplastics in the body?

Generally microplastics are formed by either the degradation of plastics disposed of into watercourses, or from the shedding of plastic fibres from fabrics, ropes etc. Large, solid plastic objects are unlikely to produce microplastics. You might as well worry about the miles of plastic piping bringing your water to your tap. It's far more likely that the microplastics are going to be in the water already from plastic pollution or shedding from washing plastic fibres.

CMV: Women have most of the social power in dating/meeting context. This is a privilege, and it should be acknowledged.

Bullet points below in no particular order: ​ \- Pointing out that men have privileges as well will not change my view. I already accept and acknowledge the privileges men receive in American society just because they are men in other contexts. ​ \- I believe that each person should be aware of and acknowledge any privileges they were born with. Anyone can have privilege regardless of gender or race. Some will have a lot of privilege, others will have very little or none. Every individual being aware of their privileges is a positive for society. ​ \- This view however is more on the macro level. Generally speaking, women are more likely than men to have the majority of social power in dating/meeting contexts, just because they are women (I will explain how below) ​ \- My view has been formed from posts on /r/tinder, as well as the personal experience I had with dating apps. ​ \- My own personal experience: I spent 11 months on Tinder, Bumble, and Coffee Meets Bagel (am currently engaged). I am 40, am in excellent physical shape, and am objectively attractive (full head of hair and conventionally attractive facial features, well defined arms/chest/stomach, proper % of body fat, 6'0" height). I met people from 36-45 years old. In this particular age group, I very much stand out among other men in that age group. ​ I only mention this to make the point that despite "just being attractive", I still saw the privilege that women have in this context. I acknowledge being attractive helps a lot, but it doesn't make the burdens men have disappear. ​ Explanation of female privilege in dating/meeting contexts: ​ \- Men are expected to make "the first move". They have to approach the woman, not knowing whether or not she likes him. The women has the option of accepting or rejecting the man. This gives women power. ​ \- Even on Bumble, where it is setup for women to make the first move, all they do is message "hey", "hi", "sup?', etc... and then it is on the man to make the actual first move. ​ \- The man is expected to be clever and interesting or they will just get passed on for someone else. The woman can often just react to what the man does, and this is enough. ​ \- If a woman wants to make the actual first move, they have the option to do so. Few on society would look down on a woman for doing this. Men however, don't have the option of not making the first move. ​ \- On the first date, men have to assume they will be expected to pay 100% of any bills. In practice, I experienced about 50/48/2. Half the time the woman expected me to pay, almost half the time she expected to split the bills, and a few times she wanted to pay for both of us. However, a woman KNOWS the man will not expect her to pay for everything; The man does not know this. ​ \- One rarely sees videos/books about things like "99 WAYS TO PICK UP WOMEN!". There is a reason for this. Movies like Hitch, if it was a women playing Will Smith's character, and that character was helping women, would just be totally confusing to the audience and it wouldn't work. There is a reason for this. ​ \- I'm being hyperbolic here, but all an attractive woman has to do is just basically exist and be available, and they'll be able to pick up men. Even the most attractive man has to do much more than that. ​ \- In short, men have to work harder than women do to meet/date people. Men also are much more at risk of social rejection, which is very difficult for any man that has social anxiety. ​ I want to be clear. This isn't an incel thing, and I don't despise women. And I know on that first meetup/date, the woman is just as nervous as the guy is. Also, dating was still super fun and I met a lot of awesome people (plus some very weird ones sometimes). I simply have a view on what I learned socially during the dating process, and am interested in discussing it and having it changed.

It seems that a lot of your focus is on the initial meetup phase. You have several points that talk about the 'first move'. You don't have very many points that mention either continued dating scenes. Is that accurate?

Why is copying 1000 1MB files so much slower than copying 1 1GB file, given that the same amount of data is being copied?

Any process has overhead - process time needed to set up and tear down that process. Overhead is generally fixed, or close to it. As an example, let's say that copying a file take 3 operations to set up and 2 to tear down, plus 1 operation per MB transferred. For a 1000MB file, you'd have: 3+1000+2 = 1005 operations. For 1000 1MB files: (3+1+2)*1000 = 6000 operations That's not precisely how it would go down but you see the point.

[World of Warcraft]Whose genius idea was it to put portals directly to Blasted Lands into every Capital City?

Who exactly decides that the risk of these portals ever malfunctioning within the heart of your city, which other side is right next to a rather large gate that has stampeding demons fighting into the world of Azeroth, outweighs the convenience of porting to the Blasted Lands. Even if it is to boost your numbers defending the gate in the first place, wouldn't it be far easier and risk free to just gradually muster numbers the traditional way of flying/mounted/vehicles etc. It seems like demons have made it into the Blasted Lands in the first place anyway, and they already seem contained with the few out-holds Horde and Alliance have there. and exactly what is preventing that portal becoming two ways, who is maintaining the portal for those 24/7 hours 365 days a year?

The portals provide swift transportation for our officers and other important personnel, as well as to ensure a quick flow of information. Should our outposts in Outland fall, or even just the defenses around the Dark Portal, we need to know about it immediately. They are constantly maintained by rotating mages, some of which are still novices and are sent there for seasoning. The Blasted Lands provide both an opportunity for practice as well as gaining experience with demonic entities. Invaluable lessons for every mage. However if the portal sites are ever in danger of falling into enemy hands the mages can sever the connection instantly.

CMV: It does not matter that Ariel is black.

Disney recently cast Ariel a black actor and I don't think it matters. Ariel is a fictional cartoon character who has no ethnic/racial ties to a specific group of people with a certain skin color. Additionally, race is not a key element of her character (i.e. you could replace all the characters in the original film including Arial (and those related to her) with darker colored actors and it wouldn't change the film a bit (other than slightly visually). Sure it might be pandering, but if you don't like it don't see it. Disney is free to cast who they want in their films and the mere fact that a cartoon character happened to be white in a film 30 years ago does mean that the character needs to be white today. I also think it's disrespectful to simply assume that the black actor is unqualified/worse than other potential white actors (simply because they are black and happened to get the role-but that is a different point). To further clarify, I don't particularly think she should be black. I just don't care what her complexion is and don't think it's important/relevant to the story/plot.

The original Hans Christian Andersen story describes her skin as "fine and transparent" and "clear and delicate like a rose petal", her legs as "white", and her arms as "white". The Little Mermaid is a national icon of Denmark and an important cultural symbol. It would be appropriate for Disney to be as respectful of the Danish version as possible since they are profiting off of the stories of another culture.

ELI5:Why Doesn't Minimum Wage Increase With Inflation?

If the point of minimum wage is to be a living wage for the people working on it, and what constitutes a living wage changes because of inflation, why are the two not automatically linked?

In other countries minimum wage is reevaluated every year, and does increase with inflation, with perhaps other factors. In the US people don't have social rights that some other countries have. But it depends on the state.

ELI5: what is cross-fit and why is it mocked so much?

Basically, it's a fitness programme/movement of sorts that involves high-intensity interval training and some weightlifting. It has a negative image among some circles because CrossFit practitioners are seen to be quite obnoxious and obsessive over it, so they won't shut up about it among their friends so much so that CrossFit's like an all-consuming cult. In part, it's due to how CrossFit is structured and advertised as a "lifestyle", with daily workouts to boot so everyday there's always something "CrossFit"-ish the "CrossFitter" friend of yours can talk (and post online) about.

How long would a lever have to be so that a human can push a object of the size of earth

I heard that in physcs it was theoratically possible if the lever was long enough but how long would it have to be?

weight of earth * distance1 = force that a human can exert * distance2 distance1/distance2 = force that a human can exert / weight of the earth If we assume that a human can exert a force of 400N, the ratio is about 6.827*10^-24 or 0.000000000000000000000006827. If the earth-mass object is at 1cm from the axis, the human would have to push from a distance of about 1.4647*10^21 metres away, which is about 9.79 billion astronomical units (avg. distance between Earth and Sun) or about 154800 lightyears. and then you'll also need some sort of a magical material that can actually withstand this I guess 400N is a bit of a low estimate because the human could just sit on the lever, but increasing it a bit won't change anything about the feasibility of this.

ELI5: why is is still hard to fall asleep when you’re sleep deprived?

When you're sleepy but want it need to stay awake, your body will produce a bunch of chemicals that will help you do so - adrenalin and others, depending on a number of factors. When you finally want to go to sleep, but your body is still flooded with those, is going to be pretty hard until they're reabsorbed. If you have a lot on your mind still, it could be that your brain keeps making more.

Why don't hummingbirds stay in flocks like other birds?

Most birds that flock do so for safety (more eyes watching for predators) or because being in a group makes it easier to find food (especially for insect-eating species in the tropics). Some larger species also migrate in flocks, which provides some aerodynamic benefits and helps group members reinforce navigation on long journeys. Hummingbirds are not targeted by many predators and generally use food sources that can't be exploited by multiple individuals so they wouldn't benefit from flocking on the breeding or wintering grounds. The few migratory species of hummingbird all make their journeys solo (even the juveniles), mostly during the day. Because they aren't gliding they can't get the aerodynamic benefits that geese do by flying in a V, and navigation in hummingbirds is (as far as we know) hard-wired instead of learned so following the group isn't as important. TLDR: because there's nothing in it for them.

ELI5: If beer is typically 95% water, why does it dehydrate us?

Your body uses a hormone called anti-diuretic hormone (ADH) to maintain sodium balance in your body. Increase ADH urinate less, decrease ADH urinate more. Alcohol suppresses the production of ADH which results in your kidneys creating more urine than the beer you’d consume in a night of binging.

ELI5: Why are American veterans committing suicide at such an alarming rate?

There are a lot of factors, particularly for those that were on the ground overseas. Just to name a few: * PTSD and other mental disorders * difficulty re-adjusting to civilian life * difficulty securing gainful employment * survivor's guilt * suicide contagion theory -- either by word of mouth or publication, hearing/reading about suicides of others can push someone already near the brink completely over the edge

ELI5: Do commanders actually give speeches before a battle (like in LOTR) and can people in the back even hear whats going on?

Modern warfare does utilize motivational speeches to generate morale among the troops. The content of these speeches are likely to include nationalist sentiments, self-professed martial superiority, focus on broadly shared values(ex:importance of protecting family.) Antequated warfare did as well. Alexander Suvorov is a prime example that comes to mind. He used to carefully plan out battles ahead of time by accounting for geographical features, possible reinforcements, etc. and then claim it was the work of god that led them to victory. On a sidenote, he is one of the few undefeated generals in history.

ELI5: If vegetables are healthy for us, why don't many people like them? Shouldn't our body crave the nutrients?

In evolutionary terms, vegetable items are available in great abundance, but salts, sugars, fats and proteins are far more difficult to obtain. Fast forward to today in the developed world, our bodies are still programmed to seek out these foods and assume that we will get plenty on vitamins ,minerals and fiber from our environment. Edit: replaced these with vegetable for clarity

ELI5: Why did the bronze age come first?

I have a cursory knowledge of history at best and very little of forging metals. Why was it easier for humans to make an alloy like bronze before just refining iron?

Bronze preceded iron as a widely worked metal due to the fact that the metals which make bronze are easily recovered from their ores, and the resulting alloy is soft enough to be easily worked with the raw materials which were then available. Copper is probably the reason why the Bronze Age came first. Copper is the perfect gateway from stone tools to metallic tools for primitive societies because: Copper exists in nature in relatively pure form, and it's common enough that it certainly would have been found in many places. Also pure copper is a striking attractive red-gold mineral. Copper can be melted at wood burning temperatures, so it can be easily cast Copper can be beaten into shapes with minimal or no heating Copper tools are superior to stone tools for many types of uses. The biggest problem with copper is it's soft and doesn't work well for tools that need a sharp edge: Axes, hatchets, knives, swords. Iron is a common element in the earth's crust, but it almost always occurs as a compound, it is very rarely to find it naturally as metallic iron. Occasionally an iron meteorite will fall from space, to provide a 'magical' source of the metal. Such rare occurrences allowed a few smiths to discover the valuable properties of iron.

A level philosophy help: analytic a posteriori

I'm teaching A level philosophy, part-time, this year. I don't have a first degree in philosophy, but I do have a masters andam completing my PhD. Most of the material I considered in my masters was modern, and my PhD is very technical and niche, so I may be missing some basics. We were looking at the distinctions analytical/synthetic, a priori/posteriori and necessary/contingent. I made the point that they varied in scope: logical/linguistic, epistemic and ontological respectively. I also wanted to get across the idea that they might not be co-extensive. In the discussion, we considered the sentence 'water is H20' Cut to the chase, I told them that this sentence was analytic but a posteriori, which to me (and Kripke) seems to be self-evident. When I went home, I found out that this was a somewhat controversial idea. The course textbook says that analytic a posteriori statements are impossible (yet puts forward Kant's rather more dubious synthetic a priori) and that this reflects a sort of consensus. So my question really is, how am I supposed to explain to my students that the analytic a posteriori is impossible, when it seem obvious to me (and Kripke) that there are many examples of such statements?

As Kant formulates it, an analytic proposition is one whose predicate is contained in its subject, or in other words, it is definitionally true - "all bachelors are unmarried" is true by definition, and requires no experience to be true (other than the experience of learning the language, arguably, but that's not what we're discussing here). Synthetic statements are those statements whose predicates are not contained in the subject, and are therefore not true merely by definition necessarily, and must relate to the world in some way. "All bachelors are happy" is a synthetic statement, it requires a relationship to the real world rather than a merely linguistic or logical relationship to be accurate. ​ In order for an *analytic a posteriori* statement to exist, it would have to be something that is true logically or linguistically without requiring a relationship to the world itself in order to be true, but also require experience and therefore is contingent on something occurring in the world. This doesn't seem to make sense, which is Kant's position. If it's an analytic statement, it doesn't need to relate to the world at all, it is true by relation of the concepts itself - "all bachelors are unmarried." You don't need any experience or empirical data to show that to be true. However, if it were *a posteriori*, then you would need experience in order to verify it. This is why it is often ruled as paradoxical. ​ However, if you consider "water is made of H2O," this requires testing to determine if it is really made of two hydrogen atoms and one oxygen atom, and not some other combination of particles. It is not true by-definition, it was found by experimentation and experience. So, it's synthetic, and a posteriori (you can't know if water is made of H2O *a priori*)

How bad is psychology really?

I'm a high school student and I always thought I'd be a Software developer or a Medical Scientist or Biomedical Engineer like most of my family. But my life got thrown off course a few years ago, I had to a take a break and now I find myself unable to force myself to do something like raw Computer science or Biomedical, and I'm keen on taking psychology and following it up all the way to grad school. I don't just want to help people or understand myself better, I've just developed a genuine interest in learning about the human mind, be it psychology or neuroscience or other branches of it. I figured I was persistent/masochistic enough to handle difficulty, and have enough financial/intellectual/emotional support from my family to pursue grad school, but I knew I had no real basis to understand the actual reality of it. I have even more doubts about it now seeing all the stories on the internet about how it's basically useless and I should consider something else even if it was my passion. So what I want to know is, is the field really that bad? I know some of the main concerns are being unable to pay back student loans, but I should mention, undergrad in my country is dirt cheap. (I would like to go to grad school somewhere else though.) So will it close too many doors or can I still do a graduate course in something like Web development/Environmental Science/Marketing/MBA, etc, things that aren't hard STEM that I might learn to like? Or should I just suffer through a Biotech (wouldn't be too bad) or an IT degree (much worse, I'm not great at math/programming) just to keep my options open or will I still be fine with a psych degree? I'd really like to give it a shot, but what would be the best course of action if psych/grad school doesn't work out?

If you're interested in combining psychology and computer science (with the added bonus of increased employability!), you should check out human-computer interaction, which is a mix of computer science, design, psychology, and economics. HCI programs are usually housed in a university's Information school. It's not offered everywhere, and even fewer places offer it at an undergrad level, but it's something to keep in mind. Some of the prominent i-schools in the U.S. include U Washington, U Michigan, Berkeley, UC-Irvine, and Carnegie Mellon.

I believe that people who are for socialism are people who hate hard work & ambition, and also do not understand the implications of taking incentives away from self-made entrepreneurs. CMV.

In a perfect world, I want every starving child to be fed, every single human to be happy, and every person to come into existence to be honest, loving, and caring. In a perfect world, I want socialism. But **we don't live in a perfect world.** Seeing that I look through the lens of **reality**, I know that most people (yes, even though who for socialism) are only looking for their own self-interest. We need police because criminals exist, we need firefighters because fires will still happen, and we need a capitalistic society because we're no longer creatures who simply just survive and replicate, but rather creatures who create change. Without rewarding the entrepreneur, we are punishing ourselves as a society. If we say that employee #2 deserves as much as the creator of the company (even if employee #2 does MORE work), then we're basically **removing the incentive to start a business**. As an entrepreneur myself who risked my life-savings to start a business with my friends, and have succeeded, it angers me that people look at me like an enemy and call me selfish for not paying my employees just as much as I take in, even though I took all the risk.

By providing a minimum under which people cannot fall, socialism **promotes entrepreneurship by guaranteeing the entrepreneur a second chance at starting their enterprise**. If fewer people have to worry about the basic necessities, then there are more people who are free to create something new instead of spending their time just surviving. Those who are happy with the minimum can choose to stagnate there. Those like yourself can pursue something bigger.

I think increases to minimum wage would INCREASE profits for low margin businesses. CMV.

Recently, while reading another post, someone stated that low margin businesses couldn't survive an increase in minimum wages, and gave the following 2 numbers. Typical Grocery store has 1% profit margin. Typical Grocery store runs a 'sales per labor hour' of $150. It seems to me though that if this is the case, then if the grocery store is currently paying $10 per hour, and it increased this to $20 per hour, then their 'costs per labor hour' go up just $10. This means the price of the basket of goods sold in a typical labor hour would have to increase from $150 to $160 to maintain the grocery stores current levels of profitabillity. **note that I'm not saying they have to sell an extra $10 worth of stuff, I'm saying they need to charge an extra $10 per $150 of stuff. This corresponds to a small, one time 7% increase in prices.**. So far then, this shows that for a low margin business such as a grocery store, a 7% increase in prices would allow a $10 per hour increase in the cost of labor, from say, $10 to $20, or from $7.50 to $17.50. I think that if we had an across the board increase in minimum wage by $10, the following would happen. 1) A dramatic increase in the spending power of minimum wage employees 2) An increase in prices - in this case, 7% for said grocery store, perhaps as high as 20% for other businesses - would allow the businesses to make the same profit per item as before 3) An increase in items sold, due to the general population having more spending money, would increase the overall profits of low-margin businesses. CMV. EDIT: created a spreadsheet showing what happens to a supply chain as the cost of labor changes. It turns out that the 7% number above is understated, however it's also the case that the increase in price is dramatically lower then the increase in wages. Link here: http://imgur.com/JZwtxFM. If you want a copy of the actual spreadsheet, pm me. EDIT2: Note that in the spreadsheet included, I assumed fixed margins for the business, while before, I assumed fixed profit for the business. EG: If something costs the business $100 to create, and their previous margins are 20%, then they sell it for $120. If their costs increase to $150 to create, they maintain the 20% margin and so sell it for $180. This results in LARGER price increases with added steps to the supply chain, and more net profit for the business, assuming the same number of goods sold. Even with this assumption, price increases still seem to be dramatically less then wage increases. EDIT3: Better way to view spreadsheet: https://docs.google.com/spreadsheet/pub?key=0AranNX_5SYsBdHJnYlVjVlRwMXdSOWZtYndHeXk3dlE&output=html

**Costs**: Increasing minimum wage by $10 increases costs per hour to the employer by *more* than $10, as there are costs that increase with the wage of the employee (such as worker's comp and unemployment insurance). The usual rule of thumb is it costs about twice an employee's yearly wage to keep them for a year, so figure costs have gone up about $20 per labor hour. **More costs**: But that's not even close to the whole story. The cost of *good* to a grocery store is going to go up too, because ... where do they get the goods from? Places that employ people, *whose cost of labor has also gone up*. So the $20/hour increase doesn't begin to capture it, because all of the goods have now gotten more expensive for the grocery store to get to sell in the first place! This effect is zero for raw goods, of course, but the more layers of supply you have, the bigger the effect, and general-public stores (like grocery stores) are at the very end of the chain, i.e. are hit the hardest. So cost of goods goes up considerably as well. (A quick estimate might be the roughly 15% we're looking at above compounded for *every step in the supply chain*.) At this point we've obliterated the 1% profit margin of the store, so let's talk about the store's price increases. **Price increases**: Let me ask you a question. If the store could just raise prices 7% and still sell the same amount of groceries, why hasn't it done so already? That'd be 7% more profit without any extra cost. ...the answer, of course, is it would reduce sales, and they'd wind up with *less* revenue than before. They've already raised prices all they think they can get away with -- that is, they're pretty sure that raising prices more will *hurt* them.

ELI5: Why do we get milk/baby teeth then lose them?

It seems a bit redundant to grow a set of teeth then lose them just to grow another set back? Are milk teeth different in terms of composition to your permanent teeth?

This is part of the growth process. Teeth are not like other bones. The bone in your arm can just grow as you grow, but teeth do not grow, so when you need bigger teeth to fit into your bigger mouth, the solution is to grow entirely new teeth.

[The Culture] Are there non-sublimed, non-transcended civilizations in the galaxy that are more advanced and powerful than the Culture?

What about equals in terms of strength and technology?

There are plenty of equals to the culture, who are referred to as 'high level involved' or 'optimae' by civilizations which aren't quite on the cultures level. Despite the inevitable-in-retrospect conclusion of the Culture-Idiran war, the Idirans were roughly on par with The culture before losing the war, and had allies even *more* on par with The culture who didn't want to fully commit to a war, but did want to see The culture knocked down a peg. Overall, equivalent tech civilizations are normally on good terms with The culture, and vice-versa, but differ with them on various points. The culture is much more reliant on minds than any of their technological equivalents, and tends to be more involved with 'lesser' species through their Special Circumstances agents.

ELI5: How is the velocity of a spaceship measured?

I get that with air crafts you can use a pitot tube to measure air speed, but what do you do if there is no air

The velocity of a spacecraft is measured by taking advantage of something called the *Doppler effect.* If you've ever watched an ambulance go past you, you've heard the pitch of the siren change as it approaches and goes past you, right? That frequency shift is directly related to the object's velocity relative to the measurer's frame of reference, so if a satellite (edit: or spaceship!) is constantly broadcasting a signal on a known frequency, ground-based computers can calculate the velocity from the perceived redshift of the signal.

How does the hydraulic ram water pump work and why does it not violate conservation of energy?

[This](http://www.youtube.com/watch?v=qWqDurunnK8) video is supposed to explain how the hydaulic ram water pump works, but I am still very confused. I thought, that due to conservation of energy, it is impossible to lift water higher than the original source without an external source of energy? Why is the air in the pressure chamber not compressed in the first place? I thought water pressure was *only* a function of water depth. By that logic, the pressure in the pressure chamber should be a lot higher than the pressure in the lower part of the pump. Thus the delivery valve should never be able to open up in order to let water stream from the lower to the upper part of the pump. Also: if this thing worked, what would stop me from harvesting infinite energy from it, by using the pump to transport water to a high altitude and letting it fall back into the source pool through a system of turbines? Could someone shad some light on this apparently magical device? Thanks

In hydrostatics where the water velocity is zero or small pressure will be equal in the whole system and the maximum height of water will be the same in the whole system. Looking at the water ram it takes a moving stream of water and suddenly stops it by closing the waste valve. This sudden stop mean the pressure increases to stop the water from flowing and this pressure opens the valve into the compression chamber with the air that then seals itself, and the air pressure then manages to force water up through the higher pipe. The key is the energy taken from the water's motion to pressurize the tank. A large volume of water at low pressure is manipulated to create a smaller volume at higher pressure. If you tried to loop the device it would return a continually smaller fraction of water up the hill after each cycle.

CMV: High school students should not have to do "arts & crafts" projects.

I'm a father of two teen sons -- oldest is a freshman in college, youngest is a freshman in high school. Through the years I have helped them both with various arts & crafts (A&C) projects, from simple posters, to dioramas, to intricate 3D models made of a variety of materials. Such artistic projects can be fun and educational for younger students, but by high school, these kinds of projects should be replaced with more "Real World"-type projects/presentations -- especially using computer-based technology. Both my sons were/are in a special IT-focused program in their high school, so they did/are learning and using computer technology for many projects. But they still had/have to create some "arts & crafts" projects.* And it seems that the A&C projects are still the common/norm for the standard (non-IT-focused) curriculum. To change my view, explain how A&C projects actually help teach/learn a (high school-level) subject better than delivering a written report, or a slide presentation, or a video -- skills that will be more necessary after high school (in university or career). *I am helping him with one right now. You know how difficult it is to build an [endoplasmic reticulum (rough and smooth)](https://www.google.com/search?q=endoplasmic+reticulum&rlz=1C1GCEA_enUS861US861&source=lnms&tbm=isch&sa=X&ved=2ahUKEwjW-IaeievnAhVCJzQIHRKAAw4Q_AUoAXoECBIQAw&biw=1284&bih=1045) from A&C supplies? I'm absolutely serious -- we are building the two forms of reticulum with A&C supplies, for high school biology.

You know how they teach some football players how to do ballet? You might think that one doesn't need to know how to do ballet in order to play football. But the reality is that the muscle memory, flexibility, and coordination involved in doing ballet helps one be a better football player. Education isn't merely about getting information into people's heads. It's about molding their brains in such a way that they can be more effective intellectually. It's one thing to learn X, Y, and Z; it's another things to learn or to gain experience in *how* to learn in the first place. Well, artsy crafts and things can help the brain development of anybody at any age. Learning to draw, for example, helps you concentrate and is very beneficial for people who have a difficult time concentrating. Doing any kind of art or craft helps a person develop creativity. So, believe it or not, being a musician or an artist can help you write better software code.

How do scientists measure the drainage basin of a river?

I read a comment on here saying that most of the continental US drains into the Mississippi River. What sources of water are they measuring, and how do they calculate the total land area that's feeding into a given river?

In the modern, this is a pretty simple task in most Geographic Information Systems (GIS). In short, if you have a digital representation of topography (digital elevation models or DEMs, think a grid of x,y,z points representing elevations) you can run flow routing algorithms (the mathematical equivalent of placing a drop of water on a pixel in the DEM and using the local slope, i.e. the relationships between that pixel and its neighboring pixels, to figure out which way the drop would flow and then doing that for every pixel to make a map of flow directions) and then flow accumulation (using the result of the flow routing to figure out which pixels flow to which other pixels downstream and/or accumulate flow from other pixels upstream) to produce a map of the drainage area upstream of any pixel in the DEM. Then it's simply a task of querying the right pixel, i.e. find the the pixel that represents the mouth of the Mississippi river and query the drainage area.

What are things everyone should know/do for their mental health?

Exercise. Eat well. Practice good sleep hygiene. Just focus on your breathing for a while a few times a day, especially when you’re anxious. Your brain is like a computer — keep it running constantly, never closing any programs or windows, and it will affect performance.

Why is Social Darwinism always looked down upon in philosophy? How has it been disproven?

Thank you

Basically, it boils down to the fact that Social Darwinism attempts to use a descriptive theory in a prescriptive manner. Darwinian evolution tells us about how things came to be the way that they are. Ethics, on the other hand, aims to tell us how we ought to be. For this reason, when you try to apply Darwinian theory to ethics, things get really funky really fast. Making the argument, "this is how things are so this is how things ought to be" is commonly known as the naturalistic fallacy, and it can yield some pretty crazy results. In fact, Social Darwinism was used to support eugenics movements as late as the 1900s when people tried to apply the survival of the fittest theory prescriptively and concluded that people with "unfit genes" (low IQ, physical deformities, etc.) shouldn't be allowed to reproduce. It's kind of like Hume's whole you can't derive an ought from an is argument, but it's a lot more complex because evolution is incredibly complicated and multifactorial. Evolution is all about environment. As a result, you can't just look at an individual and be like, "oh yeah, they're the fittest," because the definition of fitness changes drastically depending on time and location. Social Darwinism can certainly be helpful to deepen our understanding of our species and behaviors, which we might be disposed to, but generally, people agree that it's illogical to apply the theory to ethics.

[Harry Potter] How come Fenrir Greyback's werewolf form looks much more horrific than Professor Lupin's?

In Prisoner Of Azkaban Professor Lupin's werewolf form is hairless except for the top of his head I believe and he looks like a typical werewolf besides the hairlessness but Fenrir Greyback who always almost looks like a werewolf even in human form has I think official artwork depicting his werewolf form and it is downright horrific, he looks vile and just awful. So how come Lupin looks mostly like a regular werewolf and Greyback looks like some demon??

Certain health and medical conditions are psychosomantic, meaning a person's state of mind can have an effect on their health. Remus mostly rejects his affliction and treats it as a curse that needs to be controlled, while Fenrir revels in being a werewolf and is so depraved that he has turned to cannibalism (which itself is known to cause insanity).

ELI5: Why do almost all animals seem to like scratches?

For social animals like humans and apes, grooming is a social adaptation that was used to bond with the tribe and was beneficial for removing parasites. For less social animals, it’s still a way of staying clean. Animals that don’t groom each other will still rub against trees or whatever to get things off their fur. Because removing dirt and parasites was an evolutionary advantage that promotes survival, the brain evolved to reward this type of behavior, making it feel good even to animals that don’t necessarily scratch each other in the wild. This is especially obvious when you consider where we like to be scratched (for humans, our backs, or for cats it’s often right by their tail). They’re the areas we can’t reach on our own.

ELI5: How do we actually know what vitamins and minerals are in the foods we eat

Bananas , sweet potatoes , and squash, are all high in vitamin k. Aside from Google and health books, how can we find those vitamins and what do they look like ?

We have data from processing samples in a Mass Spectrometer. The sample is broken down into its chemical components and the spectrometer identifies the quantities of each chemical. So we get the exact amount for the small sample and the scientists scale up and give an educated guess as to how much for a full serving/individual food.

ELI5: How can companys require MANDATORY overtime. It's not in my scope of availability.

If it's legal or not depends entirely on your contract and where you are in the world. Apparently, in some industries, this is pretty standard.. things like software development will routinely have an expectation to do overtime.

Eli5: I seriously can’t wrap my head around the idea of “time is relative”.

I just don’t get how time is faster and slower on planets that aren’t Earth and how this affects how we age as well.

Time being relative is a byproduct of the fact that the speed of light in a vacuum is a constant regardless of your frame of reference. That probably sounded science-jargony and didn't help, so let's take a step back and talk about velocity/speed and frames of reference. There's a classic physics thought experiment where you have a truck going down the highway at 55 miles per hour, and in the back of the truck is an athlete or robot or something that can throw an object out of the back of the truck at 55 miles per hour going the other direction. From the frame of reference of the truck, the ball will be going backwards at 55 miles per hour (because the robot/pitcher/whatever and ball were stationary from the reference point of the truck), but if you're looking at this from the side, the ball will seem to stay right where it was released, because the imparted force that accelerates the ball to 55 miles per hour backwards is exactly cancelling out the forward velocity (from earth's reference frame) that was bestowed onto it by the truck. Now here's the next part of the trick, and where our intuition fails us: *Light in a vacuum moves at the same speed no matter what you're doing around it.* Let's take our truck and turn it into a rocket that can move at a significant percentage of the speed of light. And let's replace our ball-throwing person/robot and replace it with a flashlight. If this behaved the same way that the ball did, if we took our rocket and accelerated it to 0.5c (or half the speed of light) and from the reference frame of the earth looked at the light from the flashlight (it's a really bright flashlight), it would appear to be moving at 0.5 c as well (since it would be moving at 1c but would have to negate the 0.5c the ship was moving at), but we've tested this and despite it making no intuitive sense, *the light from the back of the rocket will be traveling at 1c (or just c)*. Similarly, if we take the flashlight on that same rocket and point it towards the front, and we take our intuition from the ball experiment, we might expect that light to be going at 1.5c, but it, too, will be going at 1c *no matter where we measure it from.* The ship sees it going at 1c, Earth sees it moving at 1c, Mars sees it moving at 1c... you get the picture. This is a case of *special relativity* - where velocity will cause time dilation and an increase in mass, weirdly. This is true of all velocities, but it's only really significant once you get closer to the speed of light. As for gravity, it's the same basic idea; the gravitational force should accelerate anything towards its center of mass, but since light's speed is constant, time in the local area gets distorted by the gravity. And as weird and alien as this all seems, we've managed to prove this experimentally using nuclear clocks and fast planes. Perfectly synchronized nuclear clocks, one left stationary at sea level and one put into a plane and flown around at a high speed by our standards but low speeds by light's standards, desynchronized as much as Einstein's equations predicted they would in those conditions.

How come in an emergency on a plane, someone on the ground will ask "How many souls on board?" Why not just ask how many people on board?

It avoids ambiguity. The count will include all humans on board, including crew and those not occupying seats (infants). The use is traditional, a carryover from nautical usage. Having a formalized script to follow during an emergency aids in keeping everyone organized and avoiding confusion and panic.

ELI5: After waking from a coma or a serious head injury, how do people forget their native language and suddenly speak a new one? Do they need previous experience in that new language?

Some people might change to another language if the part of their brain which controls the processing of their native language is damaged. Of course they must know the other language before they can speak it; brain damage isn't going to magically teach you another previously unknown language.

ELI5 why do doctors work 24 hour shifts instead of the normal 8 hour shift?

It's very simple, it ensures that in most cases one doctor would be able to work with a patient from entrance to the hospital to stabile/release. Tests, diagnosis, and treatment could be hampered if say the doctor had to hand you off to a changing shift and pass on the information gathered up to that point. It's possible that someone could be forgotten all together or that a vital bit of information could get lost in the transfer of your case. It also is easier to establish trust in care.

By guessing the rate of the Expansion of the universe, do we know how big the unobservable universe is?

So we are closer in size to the observable universe than the plank lentgh, but what about the unobservable universe.

We measure the size of the unobservable universe by measuring the curvature of the local universe. If it has zero curvature, the universe is flat and infinite. If it has negative curvature, it has a hyperbolic shape, and is also infinite. If it has positive curvature, it has a hyperspherical shape (like a sphere but in more dimensions), and we can use the curvature to work out the size of the universe. Currently it really looks like the universe is very very flat, so it looks like it's infinite. Unfortunately, all measurements must have an uncertainty, which means that it's technically possible that the universe is finite in size - it's just that the curvature is so small that we can't actually see it. Edit: For a flat universe, Ω=1. For a spherical universe, Ω>1. We have Ω=1.00±0.02. For Ω=0.98, the radius of curvature of the universe would be about 30 gigaparsecs, which is on the scale of the total size of the observable universe - although we've only observed galaxies up to about 4 Gpc, and only with tricky lensing techniques.

Research not moving forward

I just realized that I have not produced anything tangible in last six months inspite being busy all the time. Everyday goes into trivial things like making the error prone supercomputer work, moving huge files ,making ppts etc. It sucks how time passes by and I just cant get ahead. My PI is quite chilled in regards to timeline but I have financial constraints and this is the last semester for me. Any advice?

First, make a list, or perhaps a list of lists, of what you need to do to make progress and complete key milestones towards your thesis. Then dedicate time every day to completing key important tasks that progress you towards milestones. What you select per each day should be a limited and feasible subset. (There's a rather useful technique called the Ivy Lee method, and it suggests to limit your list to 6 key important things to complete per day, in order of importance. Of course this requires an awareness of what an appropriate task size is, as you divide your plans. There are far more advanced project management strategies, of course, but certainly not needed for day-to-day.) BTW, also weigh the possibility that some things you do may be productive, but that they'll take time to wrap up. Although, what's up with all the PPTs?

ELI5: How does store bought chocolate milk stay mixed so well and not separate into a layer of chocolate like homemade sometimes does?

Emulsifiers. Look at the ingredients: other than milk products, sweeteners and cocoa butter the other ingredients in a store brought chocolate are pretty much emulsifiers. What are emulsifiers? They can make oil and water combine and stay that way. In fact most kitchens have an amazing natural emulsifier in their fridge (American) or on their counter or both! The egg. Or more precisely the egg yolk. See any recipe for home made mayonnaise. If you don’t see any emulsifiers listed then either a) they didn’t use any and rely only on tempering (see below) and good quality cocoa butter or b) you live in a country where it’s not compulsory to list E numbers for chocolate (yep there is a chocolate lobby and cocoa butter is expensive, so...) Note another important way chocolate stays firm is the dark, secret art of tempering. Tempering chocolate instills fear in all but the greatest pastry chefs. All store brought chocolate is tempered in the right way. We temper by raising the temperature of the “raw” chocolate and dropping it rapidly to a specific temperature. You might see pastry chefs scrapping and manipulating melted chocolate on a bench top: this is to cool the mixture down fast enough. And why are we doing this? To make certain crystals form and dominant in the chocolate. These crystal structure is rigid enough to handle room temperature but delicate enough that at body temperature, like in your mouth, the chocolate melts. Source: Live in Belgium. Edit: yep E numbers are European but the numbers are used around the world eg E300 additive will be labeled 300 (in say Australia). Edit^2 : probably not just emulsifiers - other comments explain it better

ELI5: Why do showers/baths refresh and energize?

A very large portion of animals feel refreshed and energized after being clean. Humans feel more relaxed and comforted. Is this due to chemicals in our brain, or something else?

We are imprinted from birth (and from shared genetic behavior) that cleaning is caring. Mother or Father both increase levels of attention and care when cleaning their young. This reenforces the social connect and yields a positive interaction. That behavior is then carried forward to older independent self-care rituals like bath and shower. It's further reinforced by the isolating ones self from sources of stress and personal rituals marking that time as a moment of self-care.

Dogs and humans have been evolving alongside each other for 15,000 years. What other examples of coevolution have species benefited from most?

It’s been suggested that humans lack an adept sense of smell because they could rely on dogs’ sense of smell, and that this enabled more rapid evolution of our brains.

I think it's interesting that dogs have adapted to fulfill emotional needs as well as hunting and guard keeping needs. But yeah, look at... Pollinators for example as coevolution. A lot of plants lost the ability to reproduce without an insect being bribed to do it for them. And that got creative and weird.

Applying to jobs before end of PhD, "what is your highest level of education?" Well, it WILL BE PhD

And that's the only thing that matters, but then there are these disclaimers at the end of these online forms saying that if I perjure myself I am liable to being banned from the company and if it's a government job, federal charges... Any ideas? They are check boxes or drop downs or radio buttons - it's not like there's a spot for "will have a PhD in 3 months". I only have a BS, so I'm afraid they're just gonna filter me on that if I tell the exact truth for this point in time. My CV clearly shows I'll have the PhD in December, but still... example: http://i.imgur.com/HTr5wve.png

For a lot of U.S. gov jobs, the announcement will ask for 2+ years of post-bachelors education OR such and such degree. You won't be given federal charges for answering that, don't worry. On the resume portion, list the phd and list anticipated dec 2016. When you submit your transcripts, they'll show where you are in school as well. Any hr professional will understand what you're saying.

Why do lung transplant patients have a poorer long-term outlook than other organ recipients? Do we know what causes this?

Healthcare professional here. This is multifactorial. The most common reason is patients with a LIFELONG history of smoking which results in COPD. There are other causes but this is generally the most common cause. Post lung transplants require extensive immunosupresssive therapy which also has a number of adverse effects. It also doesn’t stop the rejection 100% entirely, rather it only slows it down. The lungs are highly vascular so preventing an immune response from occurring ever is not realistic. They WILL develop some form of organ rejection over time, though with appropriate therapy this can be delayed. These patients also tend to be typically older. Age will always be a contributing factor to survival rate especially after surgery. Also the years of smoking sky rocket their incidences of cancer as well which could also play a factor.

ELI5: how do computer parts work?

I am relatively into gaming, have my own custom PC, and have been around digital tech since I was a child. I can relatively easily operate a range of systems, and have little trouble working new systems out. What I can't for the life of me understand is how different parts communicate with one another, or how you even translate Pc parts to understand a language at all. I am aware of the rough idea of it being 1s and 0s, but how on earth do these mean anything to a computer that has no real understanding of what a 1 or a 0 is? Edit: I now have far more questions than I thought was even possible. Ill stick to my dad job and leave the computers just for playing games. Thanks everyone who tried!

How binary works: It's base-2 arithmetic. It works like base-10, which you are used to, but with only 2 numbers. So in base-10, you count from 0 to 9 and then append a 0 and count from 10 to 19, and so on. In base-2, you count 0 1, then append a zero and count again. You just have to append zeroes faster. Here's a little conversion table, decimal to binary: 0 = 0 1 = 1 2 = 10 3 = 11 4 = 100 5 = 101 6 = 110 7 = 111 8 = 1000 9 = 1001 10 = 1010 And so on. In this way you need only two digits to count as high as you want. Each number representing a 0 or a 1 is called a bit. It comes from Binary digIT. One byte contains 8 bits, and it can represent any integer from 0 to 255, like this: 0 = 00000000 ... 255 = 11111111 Now it's a matter of assigning numbers to everything else. For instance, you could say that a "1" represents an "A" and a "2" represents a "B" and so on. You continue with something like this and you assign numbers to all the letters, all the numbers, lower and upper case, emojis, and what have you. You also assign numbers as addresses to each pixel on a screen, and you assign numbers to various colors. Computers are really good at repetitive calculation, so by representing everything as numbers we can easily store, retrieve, and operate on anything. Languages, as in programming languages, are not that much different; at the most basic, there are very simple languages that use numbers to represent simple instructions. For instance, a "+" could be assigned a number, and so could a "-" and a "x" and so on. There are mathematical operations that you learn further along, perhaps in high school or in college, that have names like AND and OR and NOT; there are others, a bit more advanced, that have names like IF and ELSE. Put it all together and you can write programs that can operate on all those symbols according to rules that you define. The PC parts don't really translate things between concepts and 0 and 1. They operate mathematically on bits, and that is all. It is the collection of those bits, and the way we choose to organize them and display them, that has meaning. This paragraph makes sense to you if you speak English; to the computer it is just a series of numbers, with no particular meaning. There is a lot of software between you and me that makes it appear to you as letters on a screen; and you are the one doing the interpretation. How different parts communicate with each others is easy: they transmit signals to each other using wires. It is a bit more complex than that, and the wires are really tiny, but in the end as part of running your game the CPU will send signals through wires through wires to the memory, which will reply by sending memory contents; it will operate on some of those contents and send it as signals on wires to the GPU, wich will turn those into instructions to light pixels in a certain order and color and so on.

When you close your eyes and press on them with your fingers, why do you see weird patterns/designs?

I close my eyes and press on them with my fingers, after about 3 seconds I start to see weird moving patterns, like an optical illusion. Like http://img.gawkerassets.com/img/18dn0kik4y440jpg/ku-xlarge.jpg that but actually moving.

The photoreceptors in your eyes, in addition to regular light, are triggered by, though less sensitive to, pressure. The effect you see is your photoreceptive cells being stimulated, despite no light being present.

[Psychology] Can adults lose/never obtain object permanence?

Losing understanding of object permanence requires trauma or illness that is severe enough to cause large scale damage. Inability to understand(learn) object permanence is possible, but once again its back to severe inability of the brain to function, be that to growth or injury.

ELI5: Why are the 'Made In China' stickers and imprints necessary?

They can't be for crediting someone, because you can't give credit to a whole country. So why are they there?

U.S. law requires the country of origin of a product to be clearly displayed on the product, or on the product's container if it is enclosed. a lot of people also like to have this information available, especially in the US, because due to this law, countries build up a certain reputation for certain products.

[Star Wars] What happened to force sensitive storm troopers?

If a storm trooper trained from a young age began showing signs of being force sensitive what would the empire or first order do with them?

With the Empire, there are standing orders to look out for potential force-sensitives, who are brought to the attention of the Inquisitors. They may be recruited and trained as Inquisitors themselves - or simply disappear.

[Star Trek] How do people know when a word won't be translated by a universal translator?

Often people will say something like "your *pagh*, or soul", wherein they immediately follow an untranslated word with its (often fairly simple) Federation Standard equivalent. Why doesn't that come through as "your soul, or soul"? Even if they know some words won't be translated, you'd think they'd occasionally be mistaken about that, and we'd hear the same word twice in a row.

Sometimes, a translation program is written so certain culturally significant words are not translated. Sometimes it could be seen as sacrilegious for some words to be heard "wrong", or maybe it loses its true meaning if the translator uses an alien equivalent. This seems to be the most probable case for words like *pagh*, which has an enormous significance to the Bajoran people. Other times, like perhaps when Klingons are around, the translator is smart enough to not translate filthy language and other rude phrases to maintain propriety. But again, a great deal of the Klingon language is as sacred to them as their weapons, so many of their words remain untranslated. It's also somewhat assumed that a Federation officer would have enough cultural understanding to know what is being said anyway, at least those who serve near the border. Also, remember that oftentimes, when people are on a Federation ship or station, the crew is actually speaking the same language. It would be a chaotic/lethal disaster if an entire crew who relied on the translator to function found themselves in a situation without that technology, or the power to run it. So sometimes, an alien crewmember is translating a word FROM future English/Federation standard into their own language. Other dignitaries or diplomats are also multilingual as a sign of respect, so they may do the same.

ELI5:Why does defrosted ice taste different (and worse) than water?

If your question is specific to ice cubes in the freezer, rather than lab conditions: The ice in your freezer absorbs various smells over time....smells from the food, smells from the kitchen, smells from the likely dirty ice cube tray. Or in the case of an ice machine, smells from it. So, when that ice melts, it's some other stuff in there...not just water. That's what you are tasting.

"Dwell with yourself, and you will know how short your household stuff is."

Came across this in the beginning of Kant's *Critique of Pure Reason* and I'm totally at a loss for the meaning of the statement, let alone it's implications in the context of the preface. Original Latin: Tecum habita, et noris quam sit tibi curta supellex What does this mean and why does he say it?

He's talking about how we can solve questions of metaphysics by looking within ourselves/examining the necessary structure of our experience of the world. The metaphor is that if you live in your house, you'll end up familiar with what's available to you, in such a way as to make it clear that you had less than you thought you did. Kant's point is that when it comes to metaphysics, we can resolve all of our classical questions by realizing that the answers depend on ourselves in a crucial way. So "dwelling with yourself" here is the idea of reflecting on oneself/using one's own reasoning capacities.

ELI5: How are new data points created in a video such that a video filmed in 30 fps can be viewed at 60 fps?

How does interpolation work?

Interpolation is a process where a display unit (TV/Monitor) takes two frames and puts them together (similar to an "average") to generate an extra frame in the middle. By inserting an extra frame between each one that was recorded, you effectively double the frames per second and can bring 30 to 60.

CMV: I'm a woman but don't think women have structural barriers to success.

First of all, I realize this is not *that* unpopular of an opinion, except that I'm a 1) college student in a very liberal area and 2) a Democrat and have been for life, so this view doesn't align with many of my peers. I also want to note that I have been privileged enough to grow up fairly well-off (upper middle class) and am aware that I do not see many of the structural or societal barriers that may exist for people without my same privileges. But I took one of those political typology tests today with a friend of mine - the one from [Pew Research Center](https://www.people-press.org/quiz/political-typology/) - and got what's called an "Opportunity Democrat." The description is as follows: >Democratic-leaning and financially comfortable, Opportunity Democrats have liberal attitudes on most issues including the environment, immigration and homosexuality. They stand out from other Democratic groups in their strong belief that hard work is enough for most people to get ahead and for being somewhat less likely to see structural barriers facing blacks and women. They are supportive of U.S. engagement abroad and involvement in global markets. I want to say here that I do not believe that of racial minorities, e.g. I believe there are absolutely structural barriers to success, especially for African-Americans, but also Latinos and Native Americans. I am of color, although I'm mixed-race and also an overrepresented minority (Asian, but probably not the kind you're thinking). All that said, I don't believe that women have structural barriers to success. I think that I have worked hard, and have worked for every academic success I've had (bolstered by privilege, but also reliant to an extent on my own work), and I do not feel like I have had to work harder than my male peers. I have frequently outperformed them, even in subjects often considered "men's subjects" (science and math). I am a STEM major. Yes, some boys have been sexist, but apart from that I do not feel like I have been dissuaded by anyone. I have faith in my own capabilities and have been lucky enough to achieve good things so far. I just do not feel like my gender has been a barrier to my success. Admittedly, I am in college, and this may change in the workforce. But in the places I have worked (like for summer internships), I have not noticed much institutional sexism, either. There are definitely less women at high levels, but I feel like that can be chalked up to women being unfortunately biologically predisposed to needing to take time off to have children. My mother is also a great example of a very high powered woman who had children and went back to work and is very high ranking still. I know I live a very specific life, but I'm struggling to see what structural barriers exist that make it harder for women than men. I think with racial minorities, I can easily point to things - e.g. redlining creating poorer school districts so that even today majority-minority schools are underfunded - that are structural and make it much harder to get ahead, but I cannot with women. Especially in the West, I just don't see what I'm missing. Please CMV. I've been yelled at all day about this.

I think you're not seeing the gender barrier because you're focused on the class barrier, that is much more apparent from your vantage point. Once you have a certain status or class, all barriers are weaker compared to those experienced by those in lower classes.

ELI5: The difference between 1080i and 1080p

While you're at it, whats the difference between 1080, 720, 480, etc.?

They're names for different screen resolutions, with the number indicating the number of horizontal scan lines, i.e. 1920 x 1080, 1280 x 720, 640 x 480, etc. The i and p mean interlaced and progressive, respectively. What this means is that with 1080i, every other horizontal line is drawn, thus saving computation time and especially video size. In 1080p, *every* horizontal line is drawn. With a still picture, most people cannot tell the difference between 1080i and 1080p. With a moving video or games, however, the difference between the two becomes far more apparent. 1080p is very noticeably more clear in fast motion.

[Neon Genesis Evangelion] Why do the angels attack one by one?

Are they just not sentient enough to understand what cooperation is? Although one of them seems to understand psychological warfare. And are they waiting somewhere until it's their turn to wreak havoc? Or do they come in existence shortly before their attack.

Because each Angel is a totally unique organism with its own set of goals, priorities, and behaviors. Some Angels are sentient, some are not, some are screaming hypercubes, and some are handsome twinks. Their individual reasons also vary, as some Angels are just naturally drawn to Lillith's body like moths to a flame, and others seem to be curious about the Lillim, whether it's communicating with them directly or by interfacing with their technology. So it's difficult to judge "Angels" as one homogenous faction, or even as one unified species. Instead, it's best to ask why Zereul doesn't work with Ramiel, which is kind of like asking why a gorilla doesn't work with a colony of bees to help find food.

ELI5: how does cancer actually kill people?

The cancerous cells require massive amounts of nutrients and energy to continue reproducing and building blood vessels to the newly formed cancer cells. The depletion of energy and nutrition from the rest of the body causes strain on other necessary processes and results in some of these processes shutting down or performing below standards required to support life. This effect gets snowballed until entire organs get damaged and destroyed.

ELI5: If your body sweats in order to keep cool, what causes it to sweat when you're cold?

The ELI5 for this is that you sweat for a number of reasons, and the mechanisms that control sweating aren’t only linked to temperature regulation. Certain chemicals or nerve impulses can cause you to sweat in response to a number of stimuli, even when you’re cold. You have sweat glands that, for example, are activated by the chemical your nerves release when you’re in the “fight or flight” mode

ELI5: Existentialism

Every time I attempt to learn more about this, I become more confused.

Basically it is the idea that the meaning of life is something every individual needs to discover for themselves, rather than the idea that there is a higher power dictating a meaning for our lives.

ELI5: Why can't California seed clouds to cause rain to fall similar to what China did before their Olympic games?

Wat do you mean? Create clouds to produce rain and prevent drought? Because that's not what they did in China, there they only caused existing clouds to drop their rain before they reached the area they wanted to protect. EDIT: and even that was extremely expensive, so not really applicable for large scale use.

I feel like I have an obligation to society

I don't actually agree with this thought, but doing what I want and not caring about being productive to society nonetheless creates a sense of guilt. And I'm not able to justify myself. Hopefully you guys can explain why I shouldn't feel bad?

You need a psychologist or a counselor, not a philosopher. From a philosophical point of view, however, *obligation* is a loaded word. An obligation arises when you have a duty to act in a certain way, and duties only arise in certain relations. What is it about the /u/BeneficialStorm → society relation that gives rise to a duty for you to perform in some way? Has this obligation accrued because of something society has provided to you?

How can a feather keep it's color for so long, when other parts of many biological things tend to fade after they are no longer alive or part of said thing?

Many feathers' colors come from their structure, rather than the more common route of molecules like melanin. These molecules break down, like when chlorophyll disappears from leaves in autumn. The microscopic ridges that structurally select for reflected light of a certain range of wavelengths may be more resilient. Apparently Lexus spent 15 years developing a paint that uses the same method, called Structural Blue, that shouldn't fade in the sun.

Does Airbnb systematically displace poor people?

I’ve read the [McGill](https://upgo.lab.mcgill.ca/publication/short-term-cities/short-term-cities.pdf) study, which argues that the rise of housing used for Airbnb primarily displaces new rentals, thus restricting supply and increasing prices. My question is if there’s evidence of the distributional impact of Airbnb, particularly on displacement. I’ve seen [this](https://pdfs.semanticscholar.org/5b3f/6cfe0d0dc4df73eab449294161659d9b9965.pdf?_ga=2.199774502.945024971.1592926943-188173673.1592926943) study, but it focuses on aggregate welfare outcomes, and frankly is a bit dense for me to understand.

Reading through the figures in the second study it seems that most of the losses are incurred by highly educated, white, high income earners. The model suggests this is probably a lasting effect since PS > PL (market clearing prices of short vs long term renting by absentee landlords. When PS > PL landlords seek higher prices via short term rentals) only in high tourism locations. This makes sense since even the McGill study acknowledges that most of the displacement takes place in high income areas. The McGill study also argues that low-income areas near public transportation could be affected, as people are renting them in order to access the high-income downtown tourism hubs. To me that doesn't suggest an imminent threat to low-income housing access, but rather upward pressure on middle to upper class housing in high tourism districts. Assuming cities and states start regulating this industry appropriately it's probably going to be fine.

I don't believe the patriarchy exists, CMV.

I'll preface that i'm referring to first world countries, especially the US and UK. I believe that the patriarchy theory is fundamentally flawed on the conceptual level. People who subscribe to the patriarchy theory believe that patriarchy is a system of gender roles that privilege men over women. Therefore, men can not be disadvantaged in any way *as men*, that is, primarily because of their gender. I've often heard people try to explain away the obvious male disadvantages as being due to some more politically correct disadvantage such as race or class, or as secondary effects of discrimination against women (e.g. "benevolent sexism"). So the patriarchal explanation of male disadvantage in custody battles is that women are really the ones being disadvantaged because society that sees them only in the role of caregiver, and not because society holds bigoted ideas about men themselves. This "patriarchy hypothesis" is also why some people deny that sexism against men and misandry exist, and why some also deny that men can be raped by women. As long as people believe that men can not be disadvantaged *as men* in some things primarily because of their gender, there can be no common ground between my own views and people who subscribe to patriarchy theory, I want to try and change that. I do believe there is a social system to give power to some and not to others, but I don't believe patriarchy can possibly be correct. I believe that there is a social system that has evolved to increase the wealth and power of societies over their neighbors, and that it exploits both women and men to that end. Furthermore, I grant that economic, political, and sexual restrictions of women do exist in our society. But I also maintain that men are also exploited, especially as laborers and fighters, and that this exploitation is because of their gender, not a secondary effect of women's exploitation. Change my view.

I don't believe you can use that word without referring back to a particular vision of Patriarchy produced by a particular scholar, as the term isn't monolithic or totalizing in the way you would like to discuss it. Which feminist scholars' definitions of the process are you contesting? Because "there isn't a patriarchy" isn't a claim unless you can define it, and it's defined by a number of theorists in a number of ways, and while you may take issue with any of those in particular, your complaint seems to be laid against the outcomes of people grossly simplifying the criticism that "patriarchy" may bring to the table, and in doing so, you're not doing the term justice. Nobody said "men can't be disadvantaged by patriarchy", no meaningful theorist has proposed this, ever. Nor does patriarchy require that any effect on the masculine be considered a secondary effect of exploiting women, but a primary effect of a social order, but one which does create expectations and roles for both men and women.

eli5: Where do queen bees come from? Does one of the current queen’s eggs have a new queen in it?

Every egg can become a queen (in most bee species). When a hive needs a new queen, a larvae is selected (sometimes more than one and they'll slug it out later) and fed nothing but "royal jelly." Royal jelly is made by workers (it's secreted by some gland on their heads), and while all larvae start on a diet of royal jelly, queens get nothing but that, while all other bees are fed "bee bread" after a few days of royal jelly (a mixture of nectar and pollen).

Can you become immune to strains of bacteria?

I was under the assumption that you only become immune to viruses, but not bacteria. Is that true, and if so why?

You can definitely become immune to strains of bacteria. Immunity is subdivided into two categories: innate and adaptive immunity. Innate immunity are those features of our immunity that are static and use a somewhat "generalized" approach to protecting the individual. This includes things like the Toll-like receptors and mannose binding lectin that have broad specificity for different types of pathogens, including bacteria. Adaptive immunity relies on the production of antibodies. Antibodies are globular proteins encoded by genes the have what's called a "hyper variable region". A staggering array of mutations occur in these regions during development of a newborn, giving rise to a large array of B cells encoding antibodies that are each unique to a different antigen and expressing it on their surface. In a process called clonal selection, B cells expressing antibodies that bind to proteins from yourself are killed off, otherwise an autoimmune disease develops. Once clonal selection occurs, any antigen that binds to an antibody on the surface of a B cell (including antigens on bacteria) will trigger a cascade of responses in which the B cell starts multiplying and the B cells start excreting the antibody they encode. These antibodies can then start binding to pathogens and mediating the adaptive immune response. The concept of "gaining immunity" refers to priming/activating B cells that encode antibodies that bind to a specific pathogen. When an antigen binds and activates a B cell and initiates the adaptive response, some of the B cells that proliferate are fated to become so called "memory B cells" that persist at higher levels in the blood stream to allow the body to start responding to the same infection much faster during subsequent exposure. If an antigen from a bacterium activates its cognate B cell and stimulate formation of memory B cells that encode antibodies specific to the bacterium, you've gained immunity to it.

CMV: Ideology should no longer be important. Any new laws or changes in policy of any kind should be evidence based.

My CMV comes out of climate change concern, however I think it can be applied across many areas. There is, in my eyes, absolutely no justification in continue to let ideology dictate the course of action on how to move humanity forward. The ultimate goal of government is to bring justice, promote welfare and generate prosperity. We now have so many tools, data and resources to be able to deliver these goals while making decisions based on evidence. While a problem may have many different "solutions" based on how you see the world, data, small trials, controled experiments can provide with the answer to the optimal solution to any and every issue. Letting ideology try and solve an issue can and often does more harm than good. Edit: my view was changed within an hour. You guys are good! Thanks! _____ > *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!*

Problem is there are a lot of things people collect data on to "prove" specific ideologies. Its a real issue in social sciences where there are many ideologies competing. For example there are two major theories about where humans evolved there is the out of africa theory and the multiregional theory. Now both those theories are ideologies, with people collecting data to try and prove them. And honestly you just created an ideology... >The ultimate goal of government is to bring justice, promote welfare and generate prosperity. Boom ideology. Data only is useful if you use it to shape an outcome, its a tool. Like it or not ideology is always what guides how that tool is used.

ELI5: How is mass different from weight?

Somebody said they are different because of gravity.

Weight is dependent on gravitational force. It's a measure of that gravitational force, usually on Earth. Mass, which measures the amount of matter in an object, exists whether gravity acts on it or not. The same object has the same mass on Earth, the Moon, or in the middle of space, but has different weights at each of those locations. However, on Earth weight can be used to measure mass. Since the same gravitational force acts on all objects in the same place on Earth, comparing their weights will reveal their mass. On Earth, mass equals weight divided by the acceleration of gravity.

ELI5: Why do space telescopes use mirrors to get their images?

Large lenses exhibit a phenomena known as chromatic aberration, where the color of light is not equally refracted. This gives pictures an undesirable rainbow-y look. Mirrors do not exhibit this so they are more suitable for large sizes.

I have lost the ability to write known algorithms because of work, after 4 years.

I don't think I could write the Kruskal's minimum spanning tree algorithm under 15 minutes and plenty of others. I have been doing so much business logic at work, so that all the algorithms that I have learned at university, I can't write them in a fast manner anymore. I remember most of the names and what they do, but that's about it. Do people feel the same? Is this normal? Maybe the most important thing is that to know there is an algorithm for a specific problem and then get a snippet someone wrote in the language you work with? At the end of the day, you need to find a solution so that you can produce value, right? I have been doing some programming puzzles to help me. At work, people laugh at me for trying to get back into knowing how to code a basic data struct like a tree/graph. Today, we use what others make. We don't have to recode all of those data structures in the codebase, we use libraries. Is knowing what data structure to use for a specific problem is enough?

> Maybe the most important thing is that to know there is an algorithm for a specific problem and then get a snippet someone wrote in the language you work with? At the end of the day, you need to find a solution so that you can produce value, right? Yes

Why, on a bad connection, do websites occasionally load without CSS?

Sometimes when my connection is bad websites will load without CSS on the first try, and then when refreshed fail to load at all. This has also been the case at school, where loading a page that should be blocked occasionally work the first time (albeit without CSS), but refreshing brings up a screen saying the firewall blocked it. The network one I can potentially understand as if the webpage loads the html and then the css, and then connection happened to just break between loading those two, but the firewall one perplexes me. Screenshot: http://imgur.com/euYSQwB

The css is retrieved via a separate network transaction - first the page is downloaded and interpreted and as the browser finds other page elements that the page is requesting, the browser downloads all those elements - js, css, images, etc. Often on poor/overloaded connections those other elements will time out.

ELI5: Is there a particular reason why most prison doors' bars are vertical?

I would assume horizontal bars would make it stronger because they will have to be shorter (assuming normal door proportions) EDIT: I mean cell doors EDIT 2: Ok so its a combo of reasons like making it harder to punch thru the bars, exchange goods, use weight to bend the bars, and no climbing to prevent WWE scenarios. Aight thanks guys

There is a practical reason. Making them vertical prevents making them a ladder. In addition today in modern prisons there are mainly solide door in order to prevent trafficking of good and maintaining the privacy of inmates.

ELI5: If places like Baghdad and Cairo can reach 40-50 C in the summer, how did they become the center of civilization in ancient and medieval times when there was no air conditioning?

Ancient peoples knew how to put up shade and keep things cool in very hot climates, and both cities lie along major rivers. Almost all ancient cities are along rivers or oceans, since it (a) moderates the climate relative to nearby areas, (b) provides food and water and (c) allows trade up and downriver.

Is it inconsistent to apply both utilitarian and deontological frameworks when thinking about ethics, depending on the situation?

Example : A person who believes that killing any innocent person is immoral is inconsistent if they also believe that having some collateral damage during a bombardment is justified if this brings prosperity latter on? I am also thinking that in terms of politics and policies: A healthcare system might be considered good if it provides free and decent care, even if that means that due to budget and workflow reasons some small percentage of people might be misdiagnosed, but if a specific doctors misdiagnoses a patient of theirs (especially due to budget and workflow reasons) this is considered not only legally wrong but ethically as well.

So in some cases it seems like Deontological and Consequentialist concerns can lead to contradictory duties or obligations. But some applied ethicists think that what is happening is that both theories give rise to worthwhile and legitimate ethical concerns and ethical truths, and it is our job to parse those out in borderline cases. Some ethicists think that many moral theories have merits that are legitimate, and we should consider all of them. Many, though, like Singer believe that a single moral framework has the most explanatory power and can be used to the exclusion of other moral frameworks. Thus, any moral intuition that a Kantian might have is either false or explained and validated by a utilitarian framework, for example. Still some others believe that an amalgamation of many major moral theories serve as the validating foundation for ethics. Such as Parfit who seems to argue in *On What Matters* that kantianism, utilitariansism, and contractarianism are all, in a qualified sense, compatible to some extent. They are “climbing the same mountain”— (there are various ways of reading what this means itself though).

How does the area of a black hole's event horizon change with respect to its mass increase?

I understand that the mass of a black hole increases by the same amount of the in-falling mass. Is the (spherical?) surface of the event horizon simply related to the BH's mass as it is to its "volume?" In other words, if the BH were a physical object made of some non-compressible material, say water, for every extra drop that joined the BH its volume, and therefore surface, would increase by a given amount. Double the mass/volume and the surface would increase by (I think) 2/3. ​ Is that the same in an actual BH? ​ Is the event horizon always spherical? Even in rotating BHs?

The area of the event horizon scales with the square of the mass of the black hole. In fact, this is how the Schwarzschild radius is defined to begin with. If the area of the horizon is A (which is well-defined and observer-independent), then the "radius" is defined to be the number R such that A = 4\*pi\*R^(2). It is then a basic result that R ~ M, where M is the mass of the black hole. The volume of a black hole is not well-defined.

What is the difference between a Sea and an Ocean?

To a large extent it's just a matter of what we call them, but the major ocean basins overlie a different type of crust than most inland and nearshore seas. Oceanic crust is basaltic, formed at mid-ocean ridges, and denser, so it floats lower on the mantle. Continental crust is andesitic, formed by subduction zone volcanism, and lighter.

Why does lime juice severely burn the skin when exposed to sunlight?

A range of plants which include the citrus family contain active compounds called furocoumarins in their juice. When this compound reacts with uv-a light on skin surface, energy is released through a chemical reaction and this energy gets absorbed mostly by the skin and as a result severe burns, blisters and hyperpigmentation occurs. This reaction is also known as margarita dermatitis, because lots of cocktails contain some degree of lime or lime juice.

How can an almond help with digestion but also be indigestible?

Apparently it's called "roughage". It is "fibrous indigestible material in vegetable foods which aids the passage of food and waste products through the gut" which for example can be an almond. How come there are so many whole grains, nuts, seeds, legumes, fruits, and vegetables, that your body can't digest, but also helps digestion? To the uneducated mind, it sounds like an oxymoron.

Fiber helps with digestion by absorbing water, which softens/loosens feces. There are three basic components to digestion in the body: Propulsion, chemical/physical digestion, and absorption. Fiber helps with propulsion, but cannot be broken down properly by the body and thus can't be absorbed. Which means that it aids in the digestion of other nutrients, but can't be digested itself.

ELI5: How does raising millions of dollars during a political campaign directly correlate to that candidate getting elected?

The more money you raise, the more money you can invest in putting (high quality) political ads on TV, the more you can invest in other media appearances, the more you can invest in contacting people by telephone to get them to vote, basically, all ways of getting your name and message out there. And that is what gets you elected. Most people decide who they are going to vote for based on what they see on TV. They don't actively try and hunt down every political candidate's viewpoints and compare them. They let the media feed them some stuff and decide based on that.

Do diffused and focused mode of thinking actually exist?

I read this in a book called mind for numbers and is this an actual thing with credible research behind it or not If so how can I rapidly change between them

Yes, they are. And you don’t want to rapidly change between them. The point Dr. Oakley is making is that it takes time to learn things. You can’t cram and expect to have that information the rest of your life. You need to sit down without distractions and focus on a problem. Eventually, you will need to step away and do something else. But if you really focused on and struggled with the material, your brain is going to work on the material in the background while you do other things. Then, you have to revisit it, and practice more. The process repeats. The more you do this, the better you get. It’s similar to working out. You can’t expect to do 1 difficult workout and be jacked by the end of it. You need to rest after the workout so your muscles can grow and heal. Then, you can workout again and repeat the whole process. Eventually, you will gain muscle if you do this. Likewise, your brain needs time away from the material fo properly learn it. It’s only with repeated cycles of focus and rest (diffused mode thinking) that you can gain high proficiency. If you want to optimize your focus and rest, here are some tips: 1. When you’re learning material, you need to sit down and do it without distraction. No phone, no internet, no annoying music, no company. It should only be you and what you need to do the assignment. 2. Before you start your distraction free study session, make a little dot on a piece of paper. Stare at it for 30-60 seconds. Don’t let your eyes wander. Visual focus is followed by mental focus. This is getting your primed to focus on the task at hand. When your time is up, move directly into the task at hand. (Don’t be discouraged if the staring is hard or your attention wavers when first starting, it’s normal, just keep going). 3. When you’re finished with a study session, either take a quick 20 minute light nap, or non-sleep deep rest. This can be 5-10 minutes of mindfulness meditation or something like Yoga Nidra. 4. Get quality sleep. Try to get 8 hours of sleep (highly recommend Dr. Matthew Walker’s Book, Why We Sleep. If you like a Mind for Numbers, you’ll like this one too). Everything you learn during the day is optimized and stored during sleep. If you have poor sleep, then you’ll have poor results. Try to go to bed and wake up every day at the same time, stay away from caffeine before bed, and turn off electronics an hour before you plan to sleep. Hope this helps!

ELI5: Why do public toilet seats have an opening at the front, but home toilet seats are completely round?

International Plumbing Code and Uniform Plumbing Code in the US dictate that open front seats must be used for facilities that are made for Accessible Design. The Americans with Disabilities Act doesn't require it but plumbing code does. Nobody really likes open front seats so you usually only see them in commercial applications in the US. Home use toilet seats are closed front because that is much more comfortable for non disabled users.

ELI5: How are magnets in the road used to regulate traffic lights?

I was at a traffic light and I could help but notice that there were a bunch of metal lines in the road. I 'm assuming that the lines are magnets or something that helps the traffic lights to know when to switch. I was just wanting more detail on exactly how the system is supposed to work.

Traffic light sensors, at least historically, are specialized metal detectors embedded underneath the road. They don't use magnets specifically, but they detect how the presence of metal in a car above it alters the electromagnetic properties of the space around the coil. However, most municipalities are moving away from these kind of sensors though, in favor of miniature radar based sensors that mount to the signal post itself. Under-road type sensors are extremely expensive to fix when they do fail, as this usually requires tearing up the road for at least 24 hours (and thereby obstructing traffic.) Having a small radar sensor that mounts above ground, which you can replace in 20 minutes with a cherry-picker? This is a no-brainer.

ELI5: What happens when a modern website "breaks" and it suddenly looks like 1990s basic HTML?

Amazon was doing this to me earlier. Instead of the modern, graphics-heavy site, it was stuck on an crappy version with long lists of blue links instead of images. It finally corrected itself.

To load a page you generally need to download a HTML file with all the text in, a CSS file which describes how to format the text, then whatever images the page includes. If the CSS doesn't download properly then you get all the text, but with the browser's default styling. Eventually you'll manage to download the CSS and start seeing pages properly again.

ELI5:why do people look down on trades even though they can make a living?

at my former high school, one of the councillors liked to remind us that going into trades, such as plumbing and carpentry, is a good option for careers. Attend the local institute of technology and you'll be guaranteed a job, he said. However, almost every single grad went to university for subjects like science, engineering, or business. The school had a lot of international students who never considered trade school but after college, some of them struggled to find jobs directly related to their studies. why is trade often looked down upon, even though they are the first to find a job?

The narrative that was being presented was that the more education you get, the better your career will be (this benefits schools as they sell education at an increasingly higher and higher cost). The Information Technology sector had this revelation awhile back. Universities aren't on the leading edge of technologies, whereas small structured certification courses were. It became more beneficial to just get a MCSE (before that became meaningless) than it did to get a Comp Sci/MIS degree. To be fair to that process though, you will likely hit a lower ceiling in the trades than you will in other areas of the private sector. So it's like choosing between a guaranteed job with a nice salary or the CHANCE at getting an amazing job with an embarassingly large salary (or failing).

What does Heidegger mean with Destruktion, is that the same as Derrida's deconstruction?

Heideggerian destruktion is a hermeneutic practice specifically employed to demarcate conceptualizations of "what being is" across historical paths. Heidegger's central question and project is always "What is being?"--he is not satisfied with how the ancients, the scholastics, and even modern philosophers treated being (as beings). He thus seeks to "destroy" all conceptualizations of being hitherto; but by that he doesn't mean to just blow them apart and create something completely unrelated, but instead he seeks to transcend and integrate the former knowledge into an other, more "originary" type of knowledge. Later Heidegger differentiates between a "first beginning" and "other beginning" in Western philosophy whereas the other beginning would arise from fully grasping the first beginning. For Derrida deconstruction flows from the structuralist and post-structuralist tenets of relational essences (i.e. there are no essences apart from context) and polarity. A thing only comes to itself as related to others things; a vast network of polarities generates the meaning of language constructs. Derrida believes one side of a pole is always privileged, while the other side is marginalized. Derrida does not mean to merely "destroy" polarity either; his project is in showing that valuations of polarity-constructs are arbitrary and hence always question-worthy.

[Dune] Why aren't there any male Bene Gesserit?

And if for some reason Paul passed the gom jabbar (box and needle) test but wasn't the Kwisatz Haderach, what would the Bene Gesserit (BG) have done with a male that had precognition and had been taught bodily control and the Voice and was scheduled to inherit a dukehood? Hoped he sired a daughter so they could unite House Atreides and Harkonnen? My understanding is that a BG is basically a spice-enhanced female mentat with the added perk of the Voice, but it seems that nothing they do is outside what we see various other people do. They utilize prescience, absolute bodily and mental control, strategic thinking, and a compelling power known as "the Voice", but we see many mentats (almost all of them male) have some degree of bodily control, we see men use the spice for prescience, etc. Even though it's unknown whether Paul is the Kwisatz Haderach, he still undergoes the BG training of absolute bodily and mental control and the box-and-needle test. He still has the ability to use the Voice and this isn't treated as an unusual thing for a male to do given enough training. Navigators (male and female) use spice to see into the future to pilot ships at FTL speeds and to also see the outcome of certain events as when Paul mentions that the Emperor's Navigators are desperately trying to see into the future on how they can beat Paul and are getting frustrated that they can't see any further. Is there something more to being a BG that only women possess or do the BG simply choose to only have female members to better control humanity's future?

Reverend Mothers of the Bene Gesserit must undergo the ritual of drinking the Water of Life, converting it, and gaining access to Other Memory. Every male that has attempted to do that has died in the process. Only women and the Kwisatz Haderach are capable of passing the ritual, which is why Paul isn't confirmed to be the KH until after he does it.

ELI5: Why the senate voted against background checks for gun owners and what exactly that bill proposed.

You already need to pass a background check to buy a gun from a Federal Firearms Licensee (a gun store). Depending on state laws, one individual selling a gun to another does not need to pass a background check. Though they often must need to state they are not a felon, have a concealed carry license/permit to own a gun, or other restrictions. It would be nearly impossible to enforce background checks in private sales without a registration of all guns and periodic checks to make sure the owners still had the guns in their possession. Not to mention, this would do nothing for stolen guns or guns already being illegally sold to/from felons. Also, medical privacy laws keep mental health information from being available on background checks. TL;DR Added cost and hassle for gun owners, little if any effect for criminals

[The Matrix] At what point does the Matrix break down upon closer inspection?

Could you deduce you were living in a false reality by doing deep astronomical observations? Or experiments on elementary particles? Does every sample of soil have billions of organisms to examine? Is the earth's magnetic field and seismic activity consistent? What about at the molecular level and chemical reactions?

I suspect that the Matrix is easier to identify based on simple intuitions (e.g., deja vu) than complex analysis. Any complex analysis that we're allowed to learn is likely to be wholly handled by the Matrix programming (perhaps with histories about how certain particles can only exist in quantum states to lead us to believing that that is the case); whereas the more obvious, intuitive pieces are the one's that they can't really hide. For example, physicists are more likely to believe in superpositioning than lay people are, but who is to say that superpositioning isn't an artifact of the Matrix?

Is Batman a terrorist?

His whole deal is that he inspires terror in criminals, right?

Terrorism by definition would mean acts designed to cause terror, but usually directed at a civilian populace. Now, seeing how Gothams civilian populace have a decent chance to become criminals, maybe? Nothing like what today-governments brand terrorism, attacks like 9/11 and 7/7.