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The difference between a Titan and a God in greek mythology
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[
"You actually are right... In Greek mythology, the Titans were descendants of Uranus and Gaia. They were immortal beings with great power to rule over nature. They were the gods of their time. Eventually their children's children became the Olympians and fought the Titans for control and won... I think it was called the Titanomachy, or War of the Titans. So essentially the Olympians (Zeus, Poseidon, Hades, etc) are a younger generation of Titans who fought and defeated their elders for control..."
] |
[
"Here's a pretty good explainer. _URL_0_ Basically it comes down to different memory, different promises (reliability and service life), and different marketing."
] |
Why American TV shows generally have 20 episodes per season, as opposed to most other nations that will have, around, 6 - 10 per season.
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[
"A large amount of the money in American television comes from syndication. This is when you sell the rights to show all of the episodes to another channel. While there is no firm rule, in general it is expected that there will be at least 100 episodes before the syndication rights are sold. This allows the channel buying the syndication rights to run 5 episodes a week and have at least 20 weeks of programming, before they need to start again at the beginning. So by producing at least 20 episodes a year, it increases the chances they will reach 100 episodes before the show is cancelled."
] |
[
"To show a moving picture you needs a bunch of individual pictures all shown after another. A short clip might be 30 pictures total. A gif is pretty much just that, 30 pictures with some extra information like how long to wait before showing the next one. A modern video file like you see on youtube is a lot more complicated. They have all kinds of tricks so that less information is needed to make the 30 needed for the clip. A really important one is starting with one full picture and then only describing how that one is changed. Since the images usually look pretty similar from one instant to the next this means much less than a full 30 pictures is needed. For example if you wanted a 30 picture clip of me browsing reddit in a modern video you would only need to change the part that is my hand and eyes moving. The rest, my head and body, the wall, the chair, that wouldn't need to be changed so it doesn't need any other information after the first image is loaded."
] |
Why do many people like to shop? Why people find "joy" in owning many material possessions?
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[
"Honestly? I want to be the monkey with the most shiny rocks. Deep down, I know that's what it is. I want more food and shiny rocks than the other monkeys and I want lady monkeys to want my shiny rocks. That's what the physical urge is. There is no other way to explain why I hate the person who grabbed the last bag of doritos on the shelf, or cuts in line. That monkey gets a thing I don't have. 34 year old rational me know not to act crazy but the urges and satisfaction are there. It's the rat race, evolutionary struggle yada yada yada, finding new ways to express itself in modern society."
] |
[
"An experiment was done in which rats had electrodes connected to the pleasure centers of their brains. When researchers activated the electrode by a lever that the rodent could push, it would press the lever as much as 700 times per ~~minute~~ hour. It would prefer pressing the lever over food and water, eventually dying of exhaustion. _URL_0_ You see similar behavior in humans addicted to methamphetamine. Nothing seems to matter except their next fix, and they will forego food, water, sleep, and hygiene to get it."
] |
Why are EpiPens and Insulin shots suppose to be used on the outer thigh? How do they work so quickly?
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[
"Insulin shots aren't supposed to go into muscle, they are supposed to go into fat. Your tummy, butt and triceps area are the recommended areas to use. Some people say outer thighs, but some don't. Also, when injecting insulin, you must rotate the areas you inject or lumps _URL_0_ Source: Daughter is Type I diabetic."
] |
[
"Mosquito and flies like damp and warm environments. Hospitals, do their best to keep their environment dry and cool/freezing. Compared to the inside of a hospital, the incests prefer the garden outside where it is warmer, more wet. Nothing magical here."
] |
How did American slaves become Christians?
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[
"On a related note, I've heard that American plantation owners justified slavery by quoting the Bible. But as far as I can remember, the New Testament prescribes that slaves be treated well. How did the slavers get away with the harsh treatment?"
] |
[
"_URL_0_ They did suffer from the disease. It wasn't recognized as a health issue until relatively recently."
] |
How is Zimbabwe still operating as a country when its unemployment rate is around 95%?
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[
"95% are officially unemployed. The truth is they are likely to be unofficially employed, working the black market or subsistence farming, just not reporting their earnings or employment to the government."
] |
[
"_URL_0_ Basically, any treatment program available to a developing country includes access to free condoms and early screening tests. If caught early and treated aggressively, it is possible to rid the body of HIV (_URL_1_). In developing nations, if a person or government is likely to take the treatments, they are also likely to take preventative action. While this isn't always the case, and to answer your question, by far the biggest contributing factor to the persistence and spread of HIV is the lack of access to, or trust in, Western medicine and doctors in many cultures."
] |
What is happening on the cellular level when second degree burns occur, and why can't the body fully heal them?
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[
"The distinction between the various [degrees of burns is based on the depth of the burn](_URL_0_). First degree burns are epidermal burns - i.e. they only involve the outermost layer of the skin. Because the underlying dermis is undamaged, they quickly look red (from capillary dilation), and heal readily as the epidermal layer is replaced. Because of the increased blood flow (and the release of inflammatory cytokines in the area), that area can feel warm afterwards. Second degree burns penetrate into the dermis, which lies under the epidermis. Superficial second degree burns tend to form large blisters from the fluid that escapes from damaged capillaries. Deep second degree burns look more dry/leathery, and are often not red. Third degree burns involve all layers of the skin, and again may not look red or feel hot due to the damage to underlying vasculature."
] |
[
"When a plant grows it is utilizing substances called \"metabolites\" which is basically the stuff that allows the tree to grow. \"Primary Metabolites\" are the ones that help the tree actually physically grow bigger, they help the leaves grow in size, they help the roots grow deeper into the ground etc. Then there are \"secondary metabolites\" these are the substances that the plant creates in order to defend itself from potential hazards in it's environment such as a fungus or parasite that might harm the plant. These secondary metabolites effectively act as the plant's immune system and have powerful, anti-viral, anti-fungal and anti-microbial effects. People extract these oils from plants most commonly through a \"cold press\" technique but also frequently using co2 extraction methods. What you are left with is an oil that is unique to the plant from which it was extracted. Source: I work as a Production Manager in an Organic Pharmaceutical manufacturing warehouse"
] |
Why do some dishes leave an aftertaste, while others don't?
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[
"I would guess the school curry has significantly less fat than the restaurant one due to regulations, specifically saturated fat. This would explain both the aftertaste and the satiety issues."
] |
[
"Between the materials of the house itself, the materials of the furnishings, the various and specific cleaning chemicals and soaps used, body fragrances used, and the body odor, you'll get a fairly unique smell for each family's dwelling...possibly similar to a fingerprint."
] |
If somebody is falsely accused of a crime, and the police search their property, would the person be responsible for any crimes discovered?
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[
"Generally speaking, if they had a search warrant, and they find proof of a different crime, it doesn't matter whether the subject of the search was innocent of the original charge. If they didn't have a search warrant or [probable cause](_URL_0_) to conduct the search, or the search is otherwise deemed illegal, the pound of meth they find cooking on your kitchen stove may very well be ruled inadmissable in court. There's not generally punishment for law enforcement officers who conduct an illegal search, unless it can be demonstrated that the search was both malicious and unwarranted (\"we know you didn't do anything, but we're still going to come trash your apartment\"), and even then it's a hard thing to prove, and even then it's unlikely there'd be much in the way of real punishment."
] |
[
"Basically, instead of responding to your argument, I make up an easier argument to fight, pretend that it's what you mean, and respond to that instead. Typically the fake argument (the \"straw man\") is a more extreme version of the original argument, but not always. So if you said something like \"I think we should legalize marijuana,\" then I could turn it into a straw man like so: \"So you think we should let potheads drive while stoned? That's a terrible idea! So you're saying you want kids to get run over?\" See, you didn't say anything about driving. You didn't say anything about kids. I don't even know your opinion on driving while high, because that wasn't part of your argument at all. But I responded to that idea as if it *was* your argument, because it made me look (hopefully!) like I was right and you were wrong. I built a strawman and attacked it instead of attacking your point, which I should be doing if I wanted to discuss the issue with you like a respectful and thoughtful person."
] |
Why is it socially acceptable to criticize someone's opinions/statements, but not one's religious beliefs?
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[
"In a democracy, opinions on politics or society are an implicit recommendation for the way the country should be. It is a duty to educate your fellow citizens in matters of governance, or the whole country will suffer for it if the wrong ideas are actually implemented. Religious beliefs are generally private. Unless you have a reason to pry into that realm, it is impolite to do so, and should in any case be done with caution. If your religion requires you to proselytize, you can do that politely, and of course if someone engages you about your religion it is proper to inquire about theirs. But fundamentally it's a distinction between public and private matters."
] |
[
"In science, \"theory\" often with a capital T is the highest and most complete way to describe some aspect of nature. A scientific theory generally contains a set of principles which have predictive power and explains a set of observations in a cohesive package. The redshift of distant galaxies is an observable fact. The thermal radiation called the cosmic microwave background is an observable fact. The big bang theory is what we use to explain these above facts and others. We don't call it the big bang fact because tomorrow the big bang theory could be replaced with a greater and better theory because of a new observation or experimental fact. The resulting shift to a new theory could be huge, like evolution through natural selection or it could be iterative like 'spherical Earth' to 'oblate spheroid.' I really like Asimov's essay about iteration in science, * _URL_0_ Much like any human vocabulary you'll find some stuff is named funny usually for historical reasons, but this is the basic idea."
] |
Can smoking slow down the rate of wound healing?
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[
"Yes. Nicotine constricts blood vessels and reduces the circulation needed to heal. The smoke also contains a variety of chemicals that enter the bloodstream and can also impact the ability to heal and hold off infection."
] |
[
"Find a kitchen sponge. Soak it with water. Now try drying it out with a syringe. If you spent enough hours to succeed, the sponge would fall apart from the huge number of holes you've made. And lungs are much bigger than kitchen sponges and the air cavities are smaller. And there are ribs and things in the way too."
] |
What causes the grogginess or difficulty concentrating when you have a cold?
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[
"Imagine your body is a phone. Not a Samsung Galaxy S56XL, just a regular one. You go and open 30 apps and the phone suddenly starts slowing down, right? Well, now imagine the common cold is a VERY consuming app for your cellphone, some kind of new Fortnite 2 game or whatever. Your body doesn't work as well when your immune system is fully fighting the virus and it may start having difficulties to do even the most simple tasks. If the app is too heavy, your phone may crash. And that's the moment you faint. So close all your tabs, lay on bed and play Coldnite 2 until you beat the game and finally uninstall it - you can't replace your body like a cellphone, unfortunately."
] |
[
"It's called [mind-wandering](_URL_0_). It's long been thought that the [default mode network](_URL_1_) is what drives this. This network refers to a number of regions in the brain which show greater activity when people are not engaged in any active task (or are engaged in an easier relative to harder task). The idea with the default mode network is that these regions are active when you're at rest and not doing anything specific, and become suppressed when you engage in a specific task. Have a look through those Wikipedia articles, they're both pretty good, and feel free to ask more specific questions."
] |
What is it that, scientifically, makes some light 'hard' and some light 'soft'?
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[
"Soft lighting is associated with a wide light source. A wide light source gives shadows large penumbras (large soft (blurry) transitions at the edges of shadows). In contrast, a point light source makes for harsh shadows, and the harsh shadows make tiny textural details like wrinkles more apparent."
] |
[
"Your eyes aren't different. Your *mind* is. Nothing any of us see is \"as it really is\". Photons enter your eye and stimulate nerves that send impulses all the way to the Visual Cortex in your brain where those signals are rerouted, decoded and modified. What you \"see\" is entirely filtered by your mood, your past experiences, your fears, prejudices and biases. In other words, its your mind that \"sees\", not your eyes."
] |
How come diesel engine have been praised in the past and now suddenly everyone seems to be against it?
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[
"Different type of fuel and compression result in different products - diesels run in high compression and hot so they burn their fuel thoroughly, however it also causes atmospheric nitrogen to react with atmospheric oxygen, producing toxic nitrogen oxides. The recent diesel scandal was companies cheating with the engine computer to reduce nitrogen oxide output when it was detecting it's in emissions test. Petrol engines run less hot, so their exhaust contains some unburnt hydrocarbons and more carbon monoxide but also less nitrogen oxides."
] |
[
"Two main reasons- 1. Cost. Since so many fewer electric cars are produced, they don't get the same economy of scale as non-electrics. Make 100 cars, each one costs a ton. Make 10,000 cars, each one costs significantly less to make. Also, those batteries are not cheap to make. 2. Infrastructure. Where can you charge an electric car? Not too many places. So if you want to be able to drive somewhere a little farther away than work, you either have to plan hard, or you have to keep another car around (or rent a car). That's a pain. Also, it takes awhile to charge an electric car, so if you run out of juice while on the road, you'll be waiting a lot longer than the 5 minutes it takes to fill a gas tank before you're back on the road again. Or more importantly, why don't you have an electric car? It's probably the same reason that nobody else does ;)"
] |
Is there any benefit to reading a textbook from a general survey course (US, world, European etc..) for somebody looking to start reading history for personal enjoyment?
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[
"Textbooks tend to be dry, quite surface level and often present dubious versions of historical events very mater of factly. I would recomend looking into either a textbook that has high remarks for accessibility or into a general audience book with a broad scope (in my field the standard is Ian Shaw's \"Oxford History of Ancient Egypt\")."
] |
[
"greetings all. Just a moderator reminder to potential respondents of what subreddit we're in here: it's /r/AskHistorians, so do review and comply with [the subreddit rules](_URL_11_). In a nutshell: > Answers in this subreddit are expected to be of a level that historians would provide: **comprehensive and informative**. As such, all answers will be assessed against the standards of Historiography and Historical Method. You should cite or quote sources where possible. So no anecdotes, speculation, or hazy memories, and no link-dropping to Wikipedia, magazine articles, blogs, etc. Lastly, stay on topic: if anyone wants to discuss rules/moderation, kindly create a separate Meta post or send a message to the mods rather than digress from the OP's question. thanks!"
] |
The British Political Parties.
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[
"_URL_0_ sums it all up pretty well. Some personal opinion from an Englishman who is not at all politically savvy: Conservatives or Tories are essentially the upper class running the country, ruining it for everyone except the mega rich. Labour party are essentially the working class ruining the country for everyone except for the mega poor and illegal immigrants. Liberal Democrats are essentially the middle class who would probably ruin the country for everyone."
] |
[
"It might be useful if you could specify the time period you're looking for. From Elizabethan times to now, for example, or from Nelson's time to the Victorian Navy, then the question will be easier to answer."
] |
Why do snowflakes form symmetrically?
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[
"They typically don't. Snowflakes are a crystalline formation, and they crystallise along hexagonal patterns. They are roughly symmetrical because at each point when more ice crystals are forming at the edges, they are experiencing approximately the same conditions as at corresponding points of rotational symmetry. Because of the hexagonal structure there are limited ways the ice can crystallise at the edges, this limitation forces the shapes into more regular patterns. The smaller snowflakes are the more uniform and closer to symmetrical they are."
] |
[
"Depends on the antenna, some antennas try to send the signal in all directions, some try to put it in a very small beam, most try for omnidirectional or close to it. The way the antenna transmits the signal is called it's [beam/radiation pattern](_URL_0_). Google that term for lots of pretty pictures of what real antennas look like. Some wifi stations also use multiple antennas and a signal processor to create a phased array of antennas to make a virtual antenna (this is actually part of the 802.11n spec). The interference pattern can make an array of antennas act as one directional antenna, but it's done in software so the base station can quickly repoint the antenna to another user."
] |
Who killed Juvénal Habyarimana?
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[
"This is highly controversial and while there are plenty of theories on the subject - most books on the subject provide plenty of well reasoned speculation - including speculation that Habyarimana was either collateral damage or a bonus killing. I generally prefer thinking of the killing as a political certainty where many parties were complicit on one level or another. Thwarting the development democracy in the area benefited many parties."
] |
[
"Could you perhaps present us with your original source so we can see what the author writes about it? I *think* I know the answer, but I would like to know what exactly the author wrote. Also, could you remove the bonus question? We do not allow discussions of events after 1993."
] |
When testing a fluid sample of something to see if contains something specific, e.g. a blood test for a disease - how can we know 100% that this specific sample has the exact same contents as the rest of the liquid? I.e. are we 100% sure that every molecule has the same makeup?
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[
"Over time, the composition of a fluid will even out and become homogeneous. Imagine putting a drop of food dye in a glass of water. It starts out concentrated where you put it in, but after enough time, it will be evenly spread out. This process is only sped up if the liquid is mixed or otherwise disturbed (as with your blood). So unless you are testing a sample that unusually still, far removed from the source, or not very long after incident of contamination, you have a pretty good assurance that the sample is an adequate representation of the whole. And, if you aren't sure, you take multiple samples from different locations at different times. Wherever those samples agree, you have greater confidence that it is representative."
] |
[
"Imagine you are made of genetic soup. Some people have ingredients that just don't go well together and make the soup taste bad. But that's ok, because when you have a kid, we just take some of my soup and some of my wife's soup and pour it in together. So even though my soup has some bad ingredients, her ingredients can cancel them out - and some of my ingredients can cancel out her bad ingredients. But what if I had a kid with my sister? She has all the same bad ingredients I do (because we were made from the same batch) and so the soup will taste just as bad if not worse. Now imagine that for generations, my family has just been reusing the same ingredients time and time again. That soup is going to be awful."
] |
The Difference Between Inductive and Deductive Reasoning
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[
"The simplest way I describe it is: Deductive reasoning is dependent on the principle reasons being logical and true. If the principles are true the outcome/reason will be true. I.e. All cats can see in the dark. Midnight is a cat. Therefore Midnight can see in the dark. Deductive reasoning goes from the general to the specific. You're deducing the premise and the outcome. Inductive reasoning is the opposite. Whereas in deductive reasoning you go from the general to the specific, inductive reasoning goes from the specific and applies it to the general. Even if all of the premises are true in inductive reasoning, the outcome could still be wrong. I kinda think of inductive reason as more emotion or personal experience based. I.e. Midnight is a cat. Midnight is scared of the dark, therefore all cats are scared of the dark. While it may be true my cat Midnight is scared of the dark, that statement can not be applied to all cats."
] |
[
"hi! you may be interested in this section of the FAQ (link on sidebar): [Why Red vs. Blue?](_URL_0_)"
] |
Does spacetime curve toward the event horizon nearest by or toward a central geometric point of the entire black hole?
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[
"Spacetime doesn't curve toward anything. Curvature doesn't have a direction. Curvature is something that describes how initially parallel geodesics (paths of free-falling objects) diverge from each other locally, i.e., not stay parallel. A common misconception about a manifold in general is that we can talk about its curvature only if it's already embedded in some higher-dimensional space. This misconception is why it's very common for laymen to ask \"what is the universe expanding *into*?\" or any similar question. When we talk about curvature, we are talking about an intrinsic property of that manifold. Spacetime is not curving into something else."
] |
[
"Gravitational time dilation depends on the gravitational potential, not on gravitational acceleration. The acceleration itself depends on the gradient of the potential. Earth's core is at the bottom of the \"gravity well\". It's flat there, but it's still deep in the well. That's what matters for time dilation."
] |
Why does alcohol increase your risk of developing cancer?
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[
"Anything that damages cells and results in new cells having to replace the damaged ones, increases the times a cell can occur that is mutated and cancerous."
] |
[
"When cells divide they make pretty much exact copies of themselves. Introduce radiation to the equation and the copying process goes screwy and the new cell is different. Rinse and repeat over and over and you end up with body cells which are completely different in shape size and function to what they were originally supposed to do. Simplified example: photocopy a document from an original and you get a good reproduction. Now photcopy the same document with the lid of the copier open and outside light getting in. The copy you get will not be as good. Then take this poor copy and copy it again with the lid open. Do this enough times and the resulting copy will be illegible and useless."
] |
When Windows is "checking for a solution to the problem" what is it actually doing?
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[
"It's attempting to self-diagnose the problem by comparing data collected from the crash/malfunction with known error data on a Microsoft server. If the developer/distributor of the software has made a point of coordinating with MSDN, there's a chance that this will be able to identify frequently-mentioned errors, and direct users with a known issue to a solution. However, given the vast range of potential errors in the wild, the automatic bug-fixing system doesn't work terribly well. Source/Further Reading: [MSDN article on Windows Error Reporting](_URL_0_)"
] |
[
"Imagine driving a long distance on the road. Your destination is 160 miles away, so you drive along the highway at about 80mph and figure that you need about 2hours total. Then, in the middle of that 160mi, the road gets very bad (you had no chance of knowing that) so you can drive only 50mph. You don't know if the road stays that bad, so you just assume that and calculate 1.5hours until your arrival. But fortunately the road gets better after a few miles, you can drive full speed again and your estimated time of arrival changes again. Downloading a file is the same: If the current speed changes due to something you can't know beforehand, you have to recalculate the remaining time. This means sometimes that the estimated time jumps around a lot."
] |
What happens to the physical money I've deposited in my bank account when I use my credit card?
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[
"nothing. when you deposit into a bank account, you are not actually putting your money in a little cubby hole just for you. instead you are effectively buying credit with the bank, which then the bank has an agreement with you that they will allow you to cash out at any time. banks are essentially credit retailers who allow you to buy credit with money and allow you to buy money with credit."
] |
[
"Easy enough: some taxes are, by law, directed toward a specific program rather than the general revenue. When that program has an excess amount of money, Congress borrows it for its ordinary spending, but promises to pay it back with interest when that program needs it. This how it is with works with the Social Security Trust Fund. Currently, the fund takes in more in taxes than it spends in paying benefits. Congress borrows the surplus, which has the benefit that the Fund earns interest on the money. But it has to pay it back, or else Social Security will be unable to pay out benefits when they exceed that year's tax revenue."
] |
When the police gets a call for crime being done from the particular place why do they come with their sirens on? Doesn't that makes the criminals alert and gives them a chance to run off? Exclude the hot pursuits.
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[
"The sirens are to protect the policemen and other people in traffic (imagine having a traffic accident or near-miss with every travel to crime scene). It might tip off the criminals but that's less serious than whatever damage not using sirens might cause. In some cases it might even be beneficial as the criminals don't get a chance to finish their crime and run instead (e.g. mugging, breaking and entering etc. ). There are cases when this might escalate the situation (hostage taking) but those are very specific and less common than the 'smaller' crimes."
] |
[
"- If you want to predict the weather for Nov 1st, and the simulation gets you the result on Nov 23rd, it's pretty useless. - While the simulation runs, people wait for the results. Salaries are expensive; computers, less so. So, you want the computers to give the results quickly so that highly-paid people can continue working. - When you're trying to find a cure for some illness, you want it ASAP. - When you're in competition against another company, you want to be the first to get the results."
] |
Why iTunes is as bad a program as it is and why Apple doesn't create a better one.
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[
"Why don't you go to one of their... oh right *they have no competitors*. Optimizing the app *costs money*. Fixing things that are annoying but not mission critical to fix *costs money*. Since people have no choice but to use iTunes... why on earth would they spend a dollar more than they have too on the site. Apple isn't in this to make you happy, you're a rounding error to them... they are in this to make money."
] |
[
"The IRS doesn't know exactly how much money you will make this year based on a single paycheck, you might have a second job or a rental property or you might get a raise. They also don't know what deductions you qualify for or are going to take when they issue your pay cheque."
] |
What is Obama's reasoning behind drones, and why can't the US just pull its troops out of the Middle East? What will happen?
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[
"Drones are typically used to target militant commanders in the hard to access tribal regions of Pakistan. They allow the US to conduct recon in the area for longer periods without the risk of losing a pilot. Drones have also been used in Yemen to target the growing influence of Al-Qaeda in the Arab peninsula. The US troop influence in the region is propping up friendly Middle Eastern governments. The sudden removal of these troops would likely create a power vacuum in which a variety of factions would seek to challenge the weak US backed governments. If these governments fall you would see the rise of a variety of governments that could threaten the stability of the region for a variety of reasons. The destabilization of the region would have economic consequences for the Western world."
] |
[
"Let's say you're starting a business and I loan you the money to get started. You make your payments and manage to keep the lights on. Soon, you start making a profit. I, who loaned you money, don't come demanding more money because you're making the payments on which we agreed. Your buddy Jeff has a business, too, but it's not doing well. He says, \"Lend me some money so I can keep going.\" You agree. Replace \"businesses\" with \"countries\" and you've got your answer."
] |
How is a font created?
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[
"Basically, an artist writes out all of the required letters and symbols in a grid. Sometimes this is hand written, sometimes it's digital. Using a simple program, each letter is defined by it's position in the grid. This is uploaded as a font file, and then you can use it. It's really that simple, and there are [sites like this one](_URL_0_) that will let you make your own fonts for free just by filling out a template."
] |
[
"**Like this!** Oh, sorry. Forgot you weren't a real 5-year-old."
] |
Is there any evidence of animals going insane or having psychological issues?
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[
"Yes, and some of these can be used as animal models to study human psychiatric illnesses--but these animal illnesses are a little bit different. Take OCD, for example--in humans, that disease presents as a cluster of symptoms. We have animal models of many of each of these symptoms (compulsivity, or overgrooming/skin picking, or stereotyped behavior), but not necessarily of a mouse \"with OCD\". [See](_URL_1_). Other behaviors/pathologies, like [violence and aggression](_URL_0_) are harder to pin down in animals. On a more qualitative note, I think that part of the reason is because we as humans kind of define abnormal violence as something that cannot be explained by certain fundamental drives (\"killing sprees for no reason\"). An animal killing another animal over mates, territory, access to resources, etc. thus doesn't seem like \"violence\" to us, although a human killing another human over the same things may or may not, depending on the exact circumstance."
] |
[
"This occurs in sex-role reversed species, and is typically accompanied by a polyandrous mating system. Both sex-role reversal and polyandry are pretty uncommon. The northern jacana is a famous example of this. The females are more brightly colored than the males, and they defend territories that contain several nesting males. The females will mate with a male, and then lay some eggs in his nest. Females will fight with one another for territories, and sometimes destroy the nests and kill the young of other females. It should be noted that polyandry and sex-role reversal do not always co-occur. There is at least one species of monkey that is sex-role typical but polyandrous, because it takes more than two parents to take care of the offspring. In humans, limited polyandry occurs traditionally in some parts of Tibet. When resources are very scarce, two brothers will sometimes share a wife. Source: did my PhD in behavioral ecology"
] |
Doppler effect or the temperature of a star? Which one?
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[
"You could can look at lines in the spectrum caused by absorption of light by atoms, and use the width of these lines as a measure of temperature independent from the peak of the thermal spectrum. You can also use the position of these lines to make a measurement of the Doppler shift independent of stellar temperature."
] |
[
"What you are missing is that the exhaust gas velocity depends on the gas molecular mass M. You can calculate it using [this equation](_URL_0_) of the exhaust gas velocity in chocked flow. Basically the lighter the gas the faster it can go and the more efficient with you mass you are. However for a given tank (ie a given V and P) the mass of gas you carry is proportional to the molecular weight. So for a given system the total impulse is proportional to the square root of the molecular mass. Cold gas thruster are inherently low ISP so you won't do high dV maneuvers with them. Moreover their mass is relatively low compared to the spacecraft mass. So the important metric in this case is total impulse. This means that helium is actually pretty bad as a cold gaz thruster. Nitrogen (N2) is used a lot more since it will give you approximately 2.6 times more total impulse. Sorry I don't have the time for a lengthy answer right now, I hope I didn't write anything stupid."
] |
Why does rising steam from a power plant or factory appear to be relatively still from a distance, but when viewed up close it appears chaotic and quick moving? Is there a name for this effect?
|
[
"From a distance you're only viewing the largest features of the smoke cloud. Up close, you're viewing much smaller, faster moving features of that cloud. Due to the fractal nature of such an object these features are different sized but similar looking. Next time approach the cloud but be mindful to focus only on the largest features of the cloud."
] |
[
"This is called the stroboscopic effect. This image, from Wikipedia, explains it better than words really can: _URL_0_"
] |
Do bone conduction earphones protect hearing?
|
[
"There's no reason to believe that they would. Hearing loss is usually caused by damage to the inner ear, which is still getting as much sound exposure with bone conduction as it would through the normal path of sound."
] |
[
"They use a wavelength of light that is cancer causing. Do you want to sit under a cancer causing light? Plus, they aren't all that effective to stop, say a sneeze from transmitting to another person. It takes some time to kill the germs."
] |
How much legal weight does an EULA actually carry?
|
[
"No one knows. Companies put EULAs on their software products, hoping that a judge would rule that it counts as a binding contract. But that's not \"settled law\", meaning that no one really knows what a judge would rule about it an individual EULA. Sometimes, companies who put EULAs on their products try to make sure that cases never go to court, because they don't want to risk the chance that a judge might say the EULA is not binding. If no one knows for sure if a EULA is binding, most people will follow it just to be safe."
] |
[
"That person cannot legally take it home. Legal code takes precedence over a will. Thats why if someone asked you to commit a crime in a will you still can’t (which would include owning a gun if it was illegal there)."
] |
Why do dogs continue barking unless told/yelled at to stop?
|
[
"I believe it is because we have been breeding them that way for thousands of years. Think of them as the poor man's intruder alarm. Dogs that alert their owners to perceived danger should continue barking until told that it is okay. I also understand that wolves do not bark (or bark much) and this is the reason why."
] |
[
"I'll try an ELI5. Sound goes into the mic, sound gets amplified, sound comes out of the loudspeaker, the mic pics up that sound again from the speaker, and amplifies it again-in a loop. There is a slight delay in the electronics, and then a longer delay (speed of sound) in the time the sound goes from the speaker to the mic depending on how far away everything is determines whether it's a squeal or more like an echo."
] |
How does spontaneous combustion work?
|
[
"Do you mean the alleged spontaneous combustion of humans? That doesn't exist. The explanation for each case depends on the case, but usually there's a cigarette involved. In a lot of cases a person who is home alone smoking in a robe will fall asleep and drop their cigarette. The cigarette then ignites the robe, but it doesn't go up in flames like you would expect. Instead it burns more like a candle with the robe acting as a wick and the person's fat reserves acting like the wax. This causes the body to burn at a very slow and steady rate without spreading the fire. The end result is that you find an oddly burned person without much else burned around them. It looks like spontaneous combustion, but really it's just a case of someone accidentally turning themselves into a human candle."
] |
[
"I would put my money on that it is a liquid that is cheaply available and burns quite nicely."
] |
Are neutron stars considered as a single atom?
|
[
"Neutron stars are a bit more complicated that just a big cludge of neutrons. [Here](_URL_0_)'s what the insides are thought to be like."
] |
[
"They start out as a giant blob of gasses and space dust, Sort of like pizza Dough. As they continue to spin they flatten once again like pizza dough."
] |
Do governments have bank accounts? If not, where do our taxes go when paid?
|
[
"Governments have many bank accounts, normally at their private banks. The bank taxes are paid to is often called the \"Treasury\". A Treasury functions otherwise like a bank: it sends and deposits checks, transfers money, runs payrolls, and even sells debt. Other banks can include a central bank (the bank of other banks for determining the money supply and maintaining private bank stability) and trade banks (financing for business dealings)."
] |
[
"It goes where all of your sinks and toilets and showers goes. The drain pipe. For city dwellers it goes to sewers. It travels thru the sewer pipe and ends up in a wastewater treatment plant, where it's filtered for garbage, sediment settled, broken down by bacteria, then discharged into the local water zone...like river or lake or ocean for dilution. For rural dwellers, the discharge pipe goes to a septic tank where same thing happens on smaller scale, then dumped in the front or back yard underground"
] |
Why isn't time measured in metric scale past at a macro scale in science?
|
[
"People are familiar with Earth/Sun units for time (hour, day, year) and there are clocks that display these units. While there are other units, like Sidereal Time, too many events depend on the daily cycle to make megaseconds a useful unit."
] |
[
"We already use mega (M) and mili (m). micro also starts with m, the easiest way to keep the m but avoid confusion is to go to a greek letter. If you do not have access to greek letters you can also abbreviate it as u e.g. us or um for microsecond and micrometer, respectively."
] |
Why do american schools have students go from room to room for their classes,while other cultures have the teachers room hop instead?
|
[
"Not all american schools work that way. However, consider a few things: 1. \"electives\" mean students are taking different classes. 2. different performance levels means students are taking different classes (e.g. tract systems). 3. some classes have specialized equipment (lab, art, gym, etc.). These things don't all exist in all places. Some tract people as \"people\", not subjects (e.g. you're an advanced student, not advanced in math or english or biology). Many places can't afford any specialized equipment, or specialized teachers, and so on."
] |
[
"DNA is shaped like a ladder, with 4 types of rung. When a certain protein is needed, the ladder comes apart, and each rung attracts a certain kind of rung from a type of half ladder called RNA. These RNA rungs link together and float off to a factory called a ribosome. This is called [Transcription](_URL_0_) In the ribosome, the RNA rungs are grouped into threes, and each group of three attracts a building block called an amino acid. The amino acids form their own chain along the RNA, then separate. This step is called [Translation](_URL_1_ separation, the unique shapes of each link in the amino acid chain cause the whole chain to fold up into a special shape, that your body uses as either building material, or as a tool to make processes run or stop."
] |
Would it be possible to create liquid wood in a vacuum?
|
[
"Not everything can melt. Many materials being to break down from heat before it ever reaches liquid phase; this process is called [pyrolysis](_URL_0_). Wood is one such example."
] |
[
"We aren't really sure why, but it doesn't seem that something like that can be done. Think about it like your bladder; you can build up a need to urinate, but you cannot urinate so much that your bladder is more than empty."
] |
Why are American universities overwhelming politically liberal?
|
[
"Statistically liberals are higher educated as a whole. That's not to say any one liberal is smarter than any one conservative, but overall liberals are higher educated and so are more represented in higher education. On some things liberals do represent the overwhelming scientific consensus more than conservatives, ie the truth, namely climate change and due to another statistical tendency for fundamentalist Christians to be more often conservative, anti-evolution views are more conservative than liberal. But when you get down to it, its a basic fact that the activity of seeking out new knowledge is fundamentally a progressive one not a conservative one, to accept new information and be open to new ways of thinking is at its core progressive. Conservatives exist in higher education certainly, but by their nature they tend to be drawn to pragmatics over knowledge for the sake of knowledge. They want to work within an existing system instead, that's what conservative means."
] |
[
"They don't. In fact polls on gay marriage in the [US](_URL_0_) and the [UK](_URL_1_) show almost exactly the same results."
] |
What is involved in the process of falling asleep, at what point do we lose consciousness, and why can't we remember it?
|
[
"I don't know the answer to this - but I actually can feel myself falling asleep most nights. It starts with my thoughts getting more and more weird and dream like. It's like I'm aware I'm not asleep but I can also begin to just let go and let these bizarre dream thoughts come in. And then at some point I actually am fully asleep. Does this happen to anyone else?"
] |
[
"There are a few factors at work here : Moſt chairs are deſigned to ſit at about knee height ; they generally ſupport your back, and more importantly, your butt and legs. Toilets are uſually lower, and they are made with a large hole in the middle, into which you ſink a little. This lower height, lack of ſupport, and ſlight ſinking cuts off the circulation of blood to your legs, cauſing them to fall aſleep. One other important thing to note is, that when ſitting on the toilet, people tend to hunch over, which compreſſes the nerves, hindering the blood flow to the legs and feet. Sitting like that is actually not very good for you, or for your bowel movements—the beſt way to do your buſineſs is to ſquat, but moſt toilets in the Weſt don’t well lend themſelves to this manner of uſe."
] |
I added sodium carbonate and bicarbonate to boiling water at roughly its solubility point at 100c then mixed it with soap... Can someone help a layperson understand something unexpected?
|
[
"When you make your own detergent it can often \"gelify\". A gel detergent is no different than a liquid detergent, but it can be a bit irritating to handle. A way to avoid this is to use borax, like [this](_URL_0_). Hope it helps."
] |
[
"2 reasons, physical & chemical. Physical: The lithium-ion battery in your phone requires an electrolyte (liquid) of Li+ ions. At really Low temperatures this will freeze and prevent the phone from being used. Chemical: the voltage produced by the battery depends on reversible chemical reactions. The rate of these reactions depend on temperature, pressure, ion concentration and other parameters. The important thing here is that a lower temperature will cause the reaction to slow and produce very Low voltages. This will not be enough to support the phone."
] |
What is a credit score, and what is considered a good score?
|
[
"A credit score is basically how reliable you are. Let's say you borrow twenty dollars from me, but you pay it back in a reasonable time. My trust in you would go up. If you continued to borrow & amp; repay at a responsible rate, I'd be more comfortable with lending you larger amounts of money. A credit score is basically that, but on a large, national scale. There's three agencies that evaluate your trustworthiness and issue a score up to 900. 900 is perfect, but anything over 700 is pretty good. You want to pay your bills on time, and borrow (and repay) loans to build credit. Start small with a cell phone, then work your way up to a credit card, and eventually auto and home loans. Be careful though, when you miss payments the company will probably report you to the credit agency, and your score will go down. Higher the score, the more money & lower interest you'll get. Edited numbers."
] |
[
"Often times the company subsidizes part of the initial costs in exchange for you signing a longer term contract. A classic example in the US at least is mobile phone contracts. AT & T will sell me a new iPhone for $200 if I agree to a 2 year contract. A new iPhone by itself costs at least $600. AT & T pays difference up front, with the expectation that they'll make up that money (and more) over the lifetime of the two year contract and its monthly fees. But if you decide to bail out of your contract early, then AT & T would just have to eat that $400 difference. So they have a termination fee in the contract to cover it."
] |
Are there famous political murders in history other than the Kennedy assassination that there were widespread conspiracy theories about at the time of the killing? Have historians reached a consensus on the cause of these murders?
|
[
"The consensus on the Kennedy assasination already exists. See [this answer](_URL_0_) by /u/thistorian."
] |
[
"I would recommend Hannibals Dynasty: Power and politics in the western Mediterranean by Dexter Hoyos. It goes in to fantastic detail about the groundwork Hannibal's father (Hamilcar) laid out for his son-in-law Hasdrubal and his heir Hannibal. The bulk of the book is about Hannibal and his exploits. All the dirty tricks, nasty assaults and deviously executed political ploys to ensure Barcid domination are explained in easily accessible terms. The best part is that the book assumes almost no background information of Carthaginian culture so when you finish it you'll have a firm grasp on the basics of the Republic of Carthage."
] |
What happens to the US Economy when large numbers of these recent grads are unable to afford their student loans?
|
[
"Luckily, Fed student loans are far more forgiving than Home loans... so much so that the \"bubble\" comparison is not a great analogy, as much as some media people like to bandy it about. The federal government currently offers four basic types of repayment plans: **Current repayment plans** The standard plan lets students pay the same fixed amount each month ($50 per month minimum). An extended plan stretches payments across 12 years to 25 years (available only for borrowers with loans totaling more than $30,000). A graduated plan requires lower payments in the first few years, and then the payments are increased every two years until the loan term is up. An income-contingent plan assigns payment amounts based on a percentage of the graduate's annual income (anywhere from 4 percent to 25 percent). If a borrower who opts for the last payment option never earns enough to fully repay the loan, whatever principal that is left after 25 years' worth of payments is forgiven"
] |
[
"Investors do NOT like uncertainty. Investors are well aware of--and profit from--standard risk-taking, which is (in general) a good thing. However, when there is a panic, it insinuates that it's something so out of the ordinary that no rational decisions can be made. That makes it difficult to predict market patterns, and as such people pull back on their investments and tend towards bonds and safe securities. While it probably affects the market as a whole, the negatives are distributed unevenly. Something like 9/11 caused defense contractors to rise. Oil shocks might cause transportation-dependent industries to plummet but other industies to rise. It all depends."
] |
Why are so many male models slender and not muscular if women are not attracted to thin guys?
|
[
"Models are not about being attractive to the opposite sex...they are about making clothing look good. It is easier to make clothing look good on a thin frame."
] |
[
"There's a very fascinating documentary on this concept of modern-day marketing. The documentary is called \"[Century of the Self](_URL_0_) (it's long, but very good). Essentially, the way companies used to market was by way of practicality. \"Buy this because it has amazing features.\" Now, most everything is marketed (in America at least) by way of emotion and identity. A good example is alcohol. [South Park made a very good joke about alcohol commercials work](_URL_1_). It has nothing to do with the product itself, but has to do with an image of how you might *feel* by using their product. Same with pharmaceutical drugs, same with cars. And same with perfume. It's the perception that is marketed. \"You too can be beautiful and seductive with our perfume.\" Same with soda commercials. Pretty much all major brand commercials."
] |
There was recently news about a "5G wireless network". What is the difference between 3G, 4G, and - now - 5G?
|
[
"3G,. 4G, etc just means \"generation\". So basically 5G is the next new generation of wireless equipment, protocols, etc. It's not even entirely clear which technologies are \"fourth generation\",(IE, the first LTE systems may or may not be considered 4G) The NGMNA has outlined some criteria they want 5G to be (ie, Data rates of tens of megabits per second for tens of thousands of users) but there is no infrastructure being built anywhere that is 5G More info _URL_0_"
] |
[
"A movie is just telling the GPU what colour every pixel should be, 60 times a second. The file is compressed to keep the file size down so you need enough processing power to uncompress the data fast enough to watch, but that's not too hard. A game tells your GPU where everything is in 3D space, what pattern is on each surface, where your viewpoint is and where the light sources are. Then your GPU has to do loads of work to simulate how light will hit each object to work out what you can see and so what colour each pixel of the screen should be."
] |
When pouring a powdered substance in a bowl, like sugar, it collects as a mound. However, when one shakes the bowl, it quickly flattens out. Why didn't it do this in the first place?
|
[
"The grains are like tiny pebbles: they interlock with each other's rough shapes, as well as by simple friction. So they tend to stay stacked."
] |
[
"Bad website design. This is something that people making websites should know about, and that is relatively easy to make not happen. But many website designers choose not to care about it when they're making websites, so they don't stop it from happening. Often it's because they store \"what the website content is\" and \"what the website looks like\" in a way that stops the computer from knowing what the website should look like until after it's already had a go at drawing the website, so it has to throw it away and try again. Other times, the website itself contains instructions (written in a language called \"JavaScript\") to change what the website content or look is after the website has been loaded, which has the same effect of making the computer have to throw its drawing away and start again with things in different places. See: New Reddit."
] |
Why don't all States do proportional representation instead of winner take all in the electoral college?
|
[
"Since it goes state to state as far as rules my first inclination would be power. If you live in a state with a powerful majority party, it's in the interest of that states party to go for winner take all so that the party ,with it's deep reach in all districts, can try to coerce said districts to support the candidate that the party wants to win. Smoke filled back rooms and whatnot."
] |
[
"In my economic history course there was a comparative study of landownership in pre-industrial France and England, in which differences in the size of estates and smallholdings was due to the fashion in which properties were consolidated or split up through the generations. In France (maybe this held true for elsewhere on the continent) inheritance was partible, thus tending towards smaller holdings; in England, it was by primogeniture, which tended to enlarge estates. That's very broadly speaking, and tangential to the actual question; in regions where inheritance was by primogeniture, how were twins handled?"
] |
In space movies and documentaries, there is always some scene where you are traveling through space and passing little lights all around you to simulate movement forward. Are each of those little lights Stars? Or is this an inaccurate portrayal of galaxies?
|
[
"Stars make up galaxies, so the answer is yes to both. Leaving the finer points of the impossibility of luminal or supraluminal travel aside, the depictions are also inaccurate insofar as all the light isn't compressed to a tiny blinding point of light and ultra hard radiation directly ahead in the direction of travel. Compare [this surprisingly inaccurate animation](_URL_0_) (coming from ESA, no less...) with [this more accurate depiction](_URL_2_) of what accelerating up close to c would look like. Now you know why Star Trek's Worf has such a [large cutaneous turd](_URL_1_) on his forehead, to block all that hard blueshifted radiation that's coming from straight ahead when Klingons travel the intergalactic voids. This part of Star Trek canon at least has the decency to appear somewhat based in speculative fact, not fiction (and I love Star Trek, for the record!)."
] |
[
"The USNO B catalog (the largest to date) contains about 1 billion stars and galaxies. There are roughly 300 billion stars in our galaxy, so we've cataloged about 0.3%. You can see about 6000 stars with your naked eye from a dark site with no moon. The vast distances, extinction from interstellar dust, and the fact that the vast majority of stars are smaller and dimmer than the Sun explains why we've cataloged so few. The stars are typically named numerically, either by their coordinates or with just a counter (though the details depends on the survey that catalogs them). Each survey assigns their own name to the same stars, so they have many names. For example, there are 16 names for this one (the first transiting hot jupiter host): _URL_0_"
] |
Why are black holes said to have infinite density if they have finite mass and volume
|
[
"The center of a black hole is hypothesized to be a singularity, which, ~~according to most of current theory~~ by definition, has non-zero mass in a point of zero, or non-existent volume. **edit** corrected on a technical point by /u/colechristensen"
] |
[
"Based on what we currently know about the universe, it seems like [dark energy behaves like a cosmological constant](_URL_3_). It also appears that the [universe is flat](_URL_2_). This is important, because the nature of dark energy and the curvature of the universe fundamentally determines the future of the universe. Given the apparent geometry of our universe, if dark energy is indeed a cosmological constant, it implies that the universe will likely continue to expand forever. The alternatives, such as the [big crunch](_URL_0_) or the [big rip](_URL_1_), are all currently disfavored. The most likely scenario seems to be the [big freeze or heat death](_URL_4_) of the universe."
] |
How do those lame porn advertisements make money, and why do porn sites continue to host them?
|
[
"They make money because there's a sucker born every minute. If *somebody, somewhere* wasn't clicking them, the company wouldn't pay to keep them up. It's also why spam emails are still a thing, for a lot of people. They still work on enough people to make a profit."
] |
[
"Probably the assumption that only a minority of users will install a plugin like adblock - and those tend to be users who are often influential in selecting browsers for large groups of other users (corporate, schools, etc) - so it's a good trade-off to give that small pool of users the experience they want, in return for lots of installs of chrome that don't have adblock."
] |
Does exercising in the morning really increase your metabolism all day vs exercising any other time?
|
[
"As [pointed out](_URL_0_) elsewhere in this post, exercising while fasting should have at least some difference in the effects as opposed to exercising after a huge meal. This is because while you might look the same on the outside thrughout the day, many parts and properties of your body can be in wildly different states depending on whether you just ate or haven't for 12 hours, especially your liver. Exercising in these different states will hence have some different effects. How different? I don't think I can give an estimate on that, but if a research study suggests there's a difference, I would not at all be surprised. Interestingly my biochem professor also mentioned that the food you eat immediately *after* your exercise also will get metabolized differently than food eaten well after some exercise. I haven't had the chance to confirm that or learn more about though. I can't see any reason why the time of the day by itself should have an effect however."
] |
[
"When things get hot they expand (get bigger). Inside your engine are a lot of metal things that work best with a very specific amount of space between them, measured in thousandths of an inch. When your engine is cold the metal bits are smaller and those exact spaces aren't the size they are supposed to be. Get the engine to operating temp and the metal parts get bigger making those spaces the right size and the engine operates as intended."
] |
Why do phone batteries appear to run out of charge at an increasing number rate, rather than linearly?
|
[
"I have the opposite experience. It seems like I can run on 20% for hours, but my phone drops to 80% in minutes"
] |
[
"Imagine you build a spherical shell around the sun, just bigger than the sun itself, and that the shell is absorbing all the incident radiation. Each square-meter of this shell would be receiving a very large amount of power from the sun. Then imagine you double the radius of that shell. Now, because its surface area is four times the size but it's still receiving the total output of the sun, each square meter receives one-fourth that which it was receiving when the shell was smaller. Now imagine you expand the shell even more, so that it has the same radius as Earth's orbit. Now the total output of the sun is divided among a *very* large area, so each individual area is not receiving nearly as much energy. So the light isn't losing energy, it's just getting more spread out."
] |
How is it that celebrities can change their bodies so quickly for movie roles?
|
[
"Well Christian Bale literally starved himself for his role in The Machinist - I wouldn't be surprised if other celebs were as reckless about their health to slim down for a role."
] |
[
"That's because your device has to \"prep\" a lot of configurations such as encryption keys, protocols etc. Think of it as switching the battery in your car, you first gotta unplug it, check which wire goes well, reassure you did it correctly and then proceed to turn your car on. It took you time to do all that, you really can't just instantly switch the power supply of your car."
] |
why it takes so long for the new airport facial recognition scanners to scan your face, doesn’t it only take a few milliseconds for things like the apple facial recognition, or Samsung s9?
|
[
"The phone facial recognition only needs to recognize or match one face, the face you teach it to know. The airport scanner needs to effectively identify you against a database containing millions? It's not going to be instantaneous."
] |
[
"Music isn't a competition between band mates, but racing between racers is. Fast reaction to the start gun is part of that competition. Motorsport usually does use a form of countdown, but reaction time is still important, vitally so in the case of drag racing."
] |
why does your vehicle not get morning frost on it when parked under an overhang or carport, if it is the same temperature and has the same airflow?
|
[
"Not exactly the same airflow, at least with the shelter on top. All that water vapour high in the air would first form and freeze on the shelter, versus being on your vehicle. It's like rain, really - why does your car not get wet under the shelter, except that in this case, it's really air. But air also moves, and cold air has a sinking motion too. The warm air that was around the vehicle that rises probably also helps for when it rises, if it's caught by the shelter from leaving, it's going to stay for a while to keep the area warm for a bit."
] |
[
"From: _URL_1_ FM radio works the same way that AM radio works. The difference is in how the carrier wave is modulated, or altered. With AM radio, the amplitude, or overall strength, of the signal is varied to incorporate the sound information. With FM, the frequency (the number of times each second that the current changes direction) of the carrier signal is varied. FM signals have a great advantage over AM signals. Both signals are susceptible to slight changes in amplitude. With an AM broadcast, these changes result in static. With an FM broadcast, slight changes in amplitude don't matter -- since the audio signal is conveyed through changes in frequency, the FM receiver can just ignore changes in amplitude. The result: no static at all. ----------------------- From: _URL_0_ AM also limits the loud-to-soft range of sounds that can be reproduced (called dynamic range) and the high-to-low sound frequency range (called frequency response, to be explained below)."
] |
Why is there an air conditioner thing at the top of doorways in supermarkets and kitchens?
|
[
"It's called an \"air curtain\". The constant \"sheet\" of moving air prevents the air inside the building from readily mixing with the air outside the building. This is useful when you have an entryway that is left open most of the time, to both save energy on cooling or heating the building, as well as keeping out insects."
] |
[
"This would make a big difference on a sunny day. This would change the [albedo](_URL_0_) of your house, meaning that less sunlight is absorbed by your house, and thus less radiative heat actually warms your house. One proof of this is that houses in hot climates in Europe are painted white allot, this helps to keep them cool."
] |
When did "prehistoric" become "historic"?
|
[
"This depends on the location. It occurred at different time and denotes the time when people started writing, and specifically, writing down a record of events. The term \"prehistoric\" is regarded as pejorative by some Native Americans because they didn't feel \"prehistoric\" or “primitive” before colonists arrived. As a result, many archaeologists employ the term \"pre-contact\" for what happened in the Americas when colonists who wrote came in contact with indigenous populations who didn't. That having been said, \"prehistoric\" is an appropriate term for Old World cultures who developed writing at some point, arriving at a point where they could write their own history, as opposed to leaving their story to be told exclusively by archaeologists."
] |
[
"BTW, for those that are downvoting this question, I would appreciate it if you could take a moment to explain the motivation. On reddit in general I could care less if something I write gets downvoted, but here in askHistorians it decreases the chances something I ask will get answered so if I am breaking some sort of taboo here or if something I have posted in the past has generated some hostility towards me I would appreciate the feedback. Thanks!"
] |
Do black holes die or fade away?
|
[
"Black holes evaporate due to [Hawking radiation](_URL_0_). For typical black holes (rather than micro black holes), the evaporation rate is immensely slow, and so the black hole has to stop gaining any mass (either from local objects falling in or from incident radiation) before very much happens, and even then it takes a truly mindboggling length of time. There's some estimates about the length of time and the behaviour during it on Wikipedia's [future of an expanding universe](_URL_1_) article. It estimates 10^66 years for a 1 solar mass black hole, but much longer for a supermassive black hole: 10^99 years."
] |
[
"Well it's a mixture of things. Some of it is kind of like an inertia, expanding from the big bang still. But the rules that govern the size and shape of the universe allow for it to continue to expand, depending on the relative amounts of mass and energy in the universe. From what we're seeing, there's more energy out there than mass. We're seeing that there's more mass than our normal kinds of matter, but that there's another type of energy that's different from our normal kinds of energy. *This is perfectly fine*. Science is very open to the possibility that there are new types of matter and energy, and we're only seeing the first signals of their existence. Dark matter appears to attract to itself and to normal matter, since dark matter tends to cluster around galaxies like normal matter does. We tend to find it in \"dark matter haloes,\" diffuse \"clouds\" of dark matter that extend beyond and through the galaxies themselves."
] |
What is happening in these photos of a laser?
|
[
"My guess is that those are caused by internal reflections between the several glass elements in the camera lens. Also known as [\"Lens flare\"](_URL_2_). A small percent of the light traveling through a glass lens will bounce of the glass/air junction, instead of being bent, it may then end up somewhere else on the image. As drawn [here](_URL_1_) This phenomena is most often seen with the sun having such an image, but will happen for every extremally high-contrast situation like pointing a laser in an otherwise dark picture. The diagram linked above is taken from this article _URL_0_ that has a more in-depth explanation."
] |
[
"[This is what paper looks like](_URL_0_) under a microscope. When you write on it, your pencil or pen leave crumbs of graphite, or smears of ink goo, on those fibers. [This is what an eraser looks like](_URL_1_) under a microscope. It's typically rubber, with some fine sand particles in it, and acts much like sandpaper; it will scrape away the top fibers of the paper shown above, the ones that are smeared by graphite or ink goo, to expose the \"clean\" fibers deeper inside the paper, where the graphite or ink haven't reached."
] |
Were Soviet soldiers ever forced to fight alongside the German army during WW2?
|
[
"Many soviet soldiers who deserted to the German side were used as anti-partisan units, camp guards, and to a lesser degree as front line troops. The Cossacks are a example of a ethnic group that was singled out by Stalin's policies and along with Ukrainians who willing volunteered to fight against the Soviet Union."
] |
[
"There is actually a funny story about this from early in the reign of Edward III (1327 AD). The young Edward III had just taken the reins of England from Mortimer and Isabella and had begun to wage war on the Scottish. After searching for the Scottish army in the border regions for some time, with no success, Edward promised a knighthood and land worth £100 a year to whoever led him to the Scottish. Thomas de Rokeby, a yeoman from Yorkshire, was among those who set out to find them. Thomas ended up being captured by the Scottish. He told them his mission and they thought it was funny, as they had been out looking for the English army with just as much success. They let him go back to Edward to complete his mission. He led Edward to the Scottish, received his knighthood and went on to become one of the foremost knights of the realm. [Edit] Thanks for the gold!"
] |
why are most people left or right handed? What stops us from all being ambidextrous?
|
[
"All of these responses are terrible. They are all guesses, none of them explain why a toddler shows a preference, or why ambisinister is also a thing. However, this question has been asked several times before (although the ELI5 entries are similarly useless): _URL_0_ _URL_1_ _URL_2_ _URL_3_"
] |
[
"\"Just about everyone here\" Where is \"here\" for you? It sounds like your question's premise is based on a small sample set based on personal observation. Before your question is addressed, you should be making sure the premise is valid..."
] |
How does a CVT(continuously variable transmission) work?
|
[
"A normal geared transmission switches between larger and smaller gears to change speed to power or power to speed. A CVT uses pulleys that can move apart or back together. The inside of the pulley is inclined, so as it moves apart, the diameter that the belt rides on gets smaller, and then larger again as it moves back together - simulating different sized gears. This effectively gives a CVT an \"infinite\" number of gears if it can move the pulleys together and apart smoothly. EDIT: Grammar"
] |
[
"UBI doesn't really have much to do with Communism. If anything, it's opposed to Communism since it doesn't involve popular or even government ownership of the means of production, just a redistribution after the fact of wealth generated in a capitalist or quasi-capitalist system. The basic idea of UBI is that you tax people, and everyone gets a certain amount of money regardless of whether they work or not. There are many different versions of UBI, and details vary, but that's the basic premise: redistribution of money, even without special \"need.\" It's a human thing, so it won't be immune to corruption, but given that it's supposed to be pretty straightforward, I don't think it'd be especially crazy in those terms."
] |
Why do people say they're Mexican when they were born in America?
|
[
"\"Mexican\" is not just a word to indicate where you were born, but also to describe your ancestry and culture."
] |
[
"\"Just about everyone here\" Where is \"here\" for you? It sounds like your question's premise is based on a small sample set based on personal observation. Before your question is addressed, you should be making sure the premise is valid..."
] |
Conventional wisdom is that a cavalry charge into a line of pikemen or pole-arms was suicidal. Are there notable counter-examples, and why were they different?
|
[
"Perhaps [this post](_URL_0_) and the top reply from /u/elos_ may be of help? Cheers!"
] |
[
"As a geologist who studied in the midwest and also spent time as a student archaeologist in that region, I would say that I think you'd be surprised about all the cliffs around the Great Plains. I just spent a few minutes looking around the [USGS National Topographic Map](_URL_0_) and if you look at basically any river valley you'll see a sharp drop (maybe you'd call it a bluff, a wall, something other than a cliff, but those terms are very squishy) that could conceivably kill a bison. Also think of the added effect of a stampede of animals going over the bluff and how many might be crushed."
] |
How does the air in our atmosphere not get sucked out into space?
|
[
"The same force that keeps people glued to the ground. Gravity works on air molecules as well, and the earth tends to pull the air molecules around it, towards itself."
] |
[
"They use magnetic fields to keep it away from normal matter. _URL_0_"
] |
Why are different subreddits going private? What's happening to Reddit?
|
[
"Victoria (u/chooter) was let go/fired from Reddit today, and because she does a lot of the background work behind r/IAMA it left that subreddit and a few others that also require her in a state of clusterfuck. [Here](_URL_0_) is a link to the explanation given by u/karmanaut on the whole situation."
] |
[
"The business cycle. This is just how capitalism works--it goes from boom to bust and back. Actual hard answers are complicated bits of economics that are beyond an ELI5."
] |
At what point in history do we go from confidently knowing exactly what life was like/events that took place to assuming what happened and having to approximate when things happened? and why?
|
[
"There is no actual point in time. There is only the evidence for any particular place and time For example for 100 years ago there is a wealth of evidence, and yet historians still constantly argue the detail for events at that time . WW1 still has detail that has been \"lost\" but which archaeologiss and historians still search for. What you may be looking for, is how when so little is known (I.e. Myans) that a comparatively small amount of evidence produces a comparatively large amount of understanding against what is not known"
] |
[
"Hi everyone. Since this is the kind of question that can attract non-expert responses, just a friendly reminder that all responses must comply with [sub rules](_URL_0_), and that [personal anecdotes](_URL_1_) are explicitly not permitted in /r/AskHistorians."
] |
How do you get cancer through smoking?
|
[
"Some chemicals in cigarettes are carcinogens (cancer-causing) because they can damage or \"mutate\" DNA. Cancers are all caused by a series of mutations, rather than by 1 specific mutation. They're usually mutations in genes coding for proteins that regulate cell growth and proliferation, or cells that activate apoptosis (cell death). Some individuals are born with a \"pre-disposition\" to cancer, meaning they are born with some of these mutations, so when they start to accumulate mutations by inhaling carcinogens (smoking) they're more likely to develop cancer than someone born without these mutations."
] |
[
"What you're seeing is the moisture from your lungs condensating. You need a big enough volume of air moving slowly enough to make this happen. As it gets colder, the volume and speed that works with will change."
] |
Why the imperial system is being used.
|
[
"> Because we're not filthy commies! Joking aside, that's just what was brought over. It's been relatively recent that Europe made metric standard. A few countries still use other systems locally, think some people in the UK use Stones (14lbs)"
] |
[
"This CGP Grey video does a really good job of explaining it all. _URL_3_"
] |
How do we obtain Avogadro’s Constant?
|
[
"Avogadro's number, like a lot of the \"natural constants\" is a convenient proportionality constant to allow you to relate two quantities. Often times these constants were defined using a specific set up, although the constant can be used generally. Here's an article related to your question: _URL_2_"
] |
[
"You can't see it with the naked eye, but special machines can. If you know the exact distance between 2 points A and B, and you can measure how long it takes light to go from A to B, you have all you need."
] |
Why states are allowed to pass laws stating medical marijuana is legal, but it's still against federal law?
|
[
"To further explain solinv's comment about the 10th amendment, it says: > The powers not delegated to the United States by the Constitution, nor prohibited by it to the States, are reserved to the States respectively, or to the people. Basically the federal government can't just come out and say that all drugs are illegal and expect the states to respect that law. They can just ignore it because the federal government doesn't have a right to dictate to the states how things should be outside of what is dictated in the constitution. This is called nullification. The reason why we had to pass an amendment to the constitution (18th amendment) to ban alcohol is because at the time, we understood the 10th amendment and that if we wanted something taken care of at the national level, it had to be done with an amendment to the constitution. We've somehow forgotten that little fact."
] |
[
"The word is that the Denver Colorado dispensary was funded by money received from Mexican drug cartels. The DEA got word through an informant and shut it down. Tldr: local$$= ok Cartel $$= fed jail"
] |
How do we hear sounds in our dreams?
|
[
"We aren't physically hearing those things in bed every night. Instead of using the word \"hear\" think \"create.\" Our unconscious mind is just recreating our interpretation of a known outward stimulus that's relevant to the content of the dream. Since we are not physically hearing anything, our brain creates another reality by assimilating bits and pieces of known data so effortlessly that we believe it is true until proven otherwise."
] |
[
"I would suspect something like binaural recording would come into play. You can listen to the results here: _URL_0_"
] |
Why is discovering a new particle such a big deal? What do we hope to gain from these discoveries?
|
[
"Some particle discoveries are just confirming what we already know from theory and proving it with experiments. Others show us something we didn't know and we develop new theories. For example the Higgs boson was a conformation of a theory, where as if we suddenly discovered a new quark that isn't predicted to exist then we would study it to develop new theories or alter our current ones."
] |
[
"Have you ever wondered what's inside your bouncy ball? Imagine it was too small to cut but you really, really wanted to know. What you might want to try is throwing it into something so hard that it breaks and you can see the smaller parts. Of course, if you only have another bouncy ball because that's the only thing the same size, you'd need a way to throw those bouncy balls into each other at a really fast speed. That's what the LHC does."
] |
Why do grocery carts slowly turn as you push them?
|
[
"If you push evenly on the cart then you will do the same work on both sides. Some of this energy will go to rotating the wheels allowing the cart to move. All wheels have friction as they spin around the axle. If there is more friction in the left wheel then it will lose its energy faster and it will spin slower. If your left wheel spins slower than your right wheel then the right wheel must cover more distance. Since the two wheels are attached to the cart the only way this is possible is if the cart curves to the left."
] |
[
"Our brains didn't evolve with cars in mind. They evolved with, like, being hunted by a jaguar (or whatever) in mind. So your brain doesn't know what to do with a car. It thinks hey, we're sitting, our body's not really doing anything physical, there's very little activity or stimulus... this seems like a good time to go to bed! What it gets amped up for is you running, lots of stimulus and physical exertion and excitement... in other words, the stuff you go through when being hunted by a jaguar. Try falling asleep while running. Your brain won't go for it."
] |
Can you own land on the moon? Could a nation form on Mars?
|
[
"Right now all of space is more or less agreed to be neutral territory. Whenever the day comes that someone starts forming permanent colonies on extra-terrestrial bodies, there will likely be a very serious and very important global discussion on how ownership of these bodies will work. Right now there is no clear plan in place."
] |
[
"Ignore your buzzkill friend, he's taking a small technicality on your ownership and overexaggerating it. The bank has no right to live in the property, to upgrade or alter the property, or to sell the property unless you default on your loan. And that's what ownership is. All they have on it is a lien or an interest in the property while you're paying off your loan terms. The house is the collateral of your loan, and if you default they have the right to take it back, but unless that happens, they have no ownership rights to that property. It is yours in every useful sense of the term, and your friend is a turd."
] |
The Battle of the Philippine Sea was, "the last of five major 'carrier-versus-carrier' engagements between American and Japanese naval forces." What were the other four?
|
[
"* Coral Sea (the first big carrier clash, and an Allied strategic victory) * Midway (the turning point, where the cream of the Japanese Navy was destroyed) * Eastern Solomons (which allowed the American invasion of Guadalcana to continue) * Santa Cruz (in which the Japanese won a tactical victory but failed to break the Allied hold on the sea around Guadalcanal and also suffered heavy aircrew losses that were irreplacable) * Philippine Sea (the \"Marianas Turkey Shoot\") I believe that's the consensus regarding carrier vs. carrier battles. In each, the surface forces rarely or never saw each other and the fighting took place mainly over the horizon using naval aircraft. There are exceptions to this strict rule (US scouting planes and attack planes on Midway and Guadalcanal, Japanese aircraft for both Philippine Sea and Leyte Gulf, submarine actions, etc), but overall these five battles saw the biggest clashes between naval aircraft launched from carriers during the conflict."
] |
[
"Oceans are in constant motion. This means that they surge up and down. Because the Pacific and Atlantic Ocean aren't connected anywhere *but* the Panama Canal, you're channeling the entire difference in wave height at any given time through the canal. Without the locks, that means you'd mostly get a fast running channel from the Pacific to the Atlantic... that reversed from time to time to run the other way. Navigating that channel would be an enormous effort. Instead, they install locks to prevent the water from flowing unchecked from one end to the other."
] |
The DowJones dropped 400+ points. What does this mean and how does it affect the economy/business?
|
[
"Minor dip. It'll smooth out over the long run. The real thing to watch is whether a trade war starts with China. If that happens, you can expect certain things to become more expensive and certain manufacturers to scale back their production lines."
] |
[
"Imagine you buy a shiny new toy. It costs $20. A week later, you want to sell it to a friend, but that friend will only pay $15 because he knows he could have a new one for $20. You decide not to sell. A year later, the toy has gone out of fashion. Now, your friend will only pay $5 for it. It's in similar condition to when he offered you $15, but it's less fashionable, so it's worth less. Where has the value of your toy gone? That's exactly the same place that the value of stocks go when they lose value."
] |
Why Military aircraft so expensive? (up to 700m$!), it is just jet engine and metal and some electronics (not talking about ammo) e.x:The Galloping Ghost (aircraft) = 2B $
|
[
"I think you're grossly trivializing the effort required in aerospace manufacturing and the engineering process. Ultra-light and strong metals are incredibly expensive and costly to manufacture. They also have to be engineered with incredible precision. And these jets have to be hand built. It's not like there's a factory that will be building millions of them. There are also millions of man-hours of engineering work that went into designing jet fighters, as well as countless prototypes and simulations to make sure they work. They're all built with incredibly specialized parts. It's not like you can bolt on a macbook pro onto some sheet metal and you instantly have a military fighter jet."
] |
[
"The blades were likely moving. Photographs from satellites are often composites of several photos taken in different colors. For example the camera would take a picture with all the red, then the green, then the blue and it would be stitched together afterwards. I believe this has to do with how the data is read from the sensor. This means that rapidly moving objects might have \"ghosts\" of various colors as they changed position between the data being gathered."
] |
Why do electronics get ruined by water?
|
[
"Non purified water is a wonderful conductor of electricity. electricity will follow the path of least resistance. In devices electricity is only supposed to go where it is designed to go. the water lets the electricity go places it shouldnt and the magic smoke escapes."
] |
[
"The cost of doing so exceeds the off chance you are going to drop your phone in the toilet. Also, since most people get a new phone every two years or so, it doesn't make that much sense to invest in durability."
] |
if you have a box that was completely void, how long would it take for matter to form from the subatomic particles that flicker in and out of existance?
|
[
"Statistically speaking? Never. The sum of the energy will always be the same. So if you had a whole hydrogen atom appear, it would create a deficiency elsewhere. This would be unstable on time frames humans are familiar with. Now, a box made of any \"real\" material would allow gas to slowly seep in. That would happen quickly."
] |
[
"Imagine you grew up flying in a plane. The ground looks like different colors. There's a green area over here, and a brown area over there. When you land for the first time, you're surprised that the green area is actually made up of large trees, and the brown area is made of rocks and shrubs. There are thousands of details you never noticed from the sky. We're like that. We can't see what things are made of smaller than about the size of a hair, but quantum effects happen at much smaller scales. We've only recently invented microscopes that can look at things thousands of times smaller than a human hair where quantum effects (the trees that make up the forest) start to happen."
] |
Since there's so much pushback on accepting refugees directly into first-world countries, why aren't these countries setting up refugee camps instead?
|
[
"Because they're interested in scoring political points moreso than actually solving the problem. Right now, there's a huge backlash due to the Paris attacks, so going \"boo immigration\" is a cheap way to score points for conservatives and going \"boo conservatives for being boo immigration\" is a cheap way to score points for liberals."
] |
[
"Incidentally, this is the problem that _URL_0_ is trying to solve. Here is the map of the overall plan: _URL_1_ There is enough solar energy in the Sahara desert in 6 hours to power the entire world in 1 year. From the Sahara, they plan on connecting Europe with underwater high voltage direct current lines. The problem with HVDC is that there is a 3% loss per 1000km. Another solution is to use the energy to create liquid hydrogen which can be shipped by tankers throughout the world. The problem with the hydrogen store is that creating hydrogen from electricity requires water, a scarcity in the deserts. The plan would be to ship the electricity through HVDC to Europe and convert to hydrogen there."
] |
Can shock waves from a major explosion exit the earth’s atmosphere? If so, what happens to them in vacuum?
|
[
"I think you are asking what happens to vertically traveling shock waves as they propagate upward. Waves interacting with the upper atmosphere is a very important part of the over atmospheres energy balance, but a shockwave is a special case. At very low pressures the gas molecules are spread out enough that collisions are no longer dominating movement and other forces start to become important. The bottom line is shockwaves, do not last long as more molecules go zipping past their neighbors and disperse their energy elsewhere. The upper atmosphere is where density driven waves go to die as the coherent fluid propagation of mechanical collision decays into the random motion of temperature."
] |
[
"The Republic XF-84H \"Thunderscreech\" had a propeller that exceeded the speed of sound. The main effect of this is that it was **loud**. So loud you could hear it 25 miles away, *see* the sonic boom coming off the propeller, and get injured by the sound if you stood anywhere near it. _URL_0_"
] |
Did Marco Polo ever actually make it to China? If so, to what extent do the events described in Il Milione follow reality?
|
[
"@ /u/TeemL This question has been asked a number of times in the sub, here are a couple -- [Question Exhibit A](_URL_1_) starring /u/[deleted] [Question Exhibit B](_URL_0_) starring /u/Searocksandtrees who links to a couple of other users such as /u/lukeweiss and /u/_dk **TLDR to the first question** - Yes."
] |
[
"This Week's Rundown! /u/textandtrowel on [\"How did medieval Islamic historians write about/conceptualise the history of their religion? Please also tell me about who wrote history in the medieval Islamic world, why, and what written history was used for in medieval Islamic society.\"](_URL_0_) /u/prufrock451 on [\"Why do some historians say Nazi Germany was headed for collapse due to bloated military spending, while the U.S. came out of WW2 with a massive economic boom. What's the difference?\"](_URL_2_) /u/Dubstripsquads on [\"What killed the Back to Africa movement of the late 19th and early 20th century and gave rise to integration movement?\"](_URL_1_)"
] |
Does the theory of relativity tell us that light never ages?
|
[
"There's no passage of time along a path travelled by a photon, or any (massless) particle moving at the speed of light."
] |
[
"Imagine a glass with water and sand mixed inside. If you leave it long enough, water will evaporate, leaving only sand. The act of separating is very roughly \"decay\". \"Photon decay\" roughly says that if enough time passes a photon will separate itself into smaller particles. But because it experiences no time (or go through time very slowly) the decay takes absurdly long time in our human time frame."
] |
What did Sauron want to do with Middle-Earth once he conquered it?
|
[
"He came from before the world was made and wants to unmake it. The problem is he is less powerful than the god that made it, so he cannot actually completely destroy it, and any damage he would do could be undone by one of the beings on his power level"
] |
[
"I'd like to ask a follow-up question. When do the Medes start disappearing from the historical record? I recall Atilla called himself \"King of the Medes\" (among many other titles). Were they assimilated into the \"Iranian\" (or Persian) identity of the Sassanid Empire?"
] |
For long-term investing, why should the average investor simply buy & hold irrespective of market conditions and not try to "time" the market?
|
[
"You are probably best off \"timing\" the market by dollar cost averaging, IE invest $100 a week and buy whatever you can for that $100, so if a stock is down you buy more if a stock is up you buy less. The reason an average investor shouldn't time the market is two fold, (1) they are trading in volumes where the commissions and transaction fees would eat into their earnings too much if they did frequent trades (2) They don't have the knowledge to know market trends before the savvy investors do so they are just following what everyone else is doing which usually means you are jumping in or jumping out too late. You are better off investing in an index fund or single blue chip stocks and riding it out."
] |
[
"That's just it. It takes a while to amass information and use it. An animal just does whatever comes natural, aka 'instinct'. But humans are taught and trained and learn and practice and... and... Layers and layers of information and training to get us to the point where we can actually achieve more than the previous generation. None of that comes easily, nor quickly. For to run, one must learn to walk. Apply that to any activity in life. Building. Theorizing. Testing. Proving. All these require layers of previous knowledge. For we are not animals, just here to eat and procreate. We are more than animals. But it takes practice to stay that way. Years of it."
] |
What rights (if any) did Jesus have as a Roman subject?
|
[
"As far as I know, none. Romans didn't recognize \"subjects.\" If he were a citizen (as Paul was) he could have appealed to the emperor, but without citizenship Roman law didn't give a flying fuck. If he were upper class, he might have had some access to imperial government through patronage networks, but what patron is a carpenter from Galilee going to have? Roman provinces are, I think, technically theaters of war, even if there is not an active conflict or an army present. The senate can issue orders to governors which sometimes governors felt compelled to accommodate (as Cicero did in his tenure in Cilicia), and the senate could... well impeach isn't quite the right word, but Cato thought Caesar was acting out of line in his tenure of Cisapline Gaul, and wanted to bring charges. But in practice? What is the senate going to do? The governor's hundreds of miles away and probably has troops. He acted pretty autonomously."
] |
[
"There is a good deal of room for fresh responses to this question. But I briefly summarised the main controversies [in an earlier thread here](_URL_0_). The short answer is that we have no certainties about this at all, only a lot of supposition and a certain amount of reasonable deduction. Even the discovery of fresh contemporary documentation in the last couple of decades has not really moved us any further forward."
] |
In college, if the department or professor choses which textbook to use, why do they not select free, open-source textbooks for lower-level classes.
|
[
"In my experience, professors chose books because 1) They wrote the book 2) Their friend wrote the book 3) It's the BEST book, in their opinion or 4) It's the BEST book, in their opinion, under a certain price. Open source doesn't always mean better or higher quality. Iin the case of things like Algebra (why are you taking algebra in college?!?), it's probably the first or second reason."
] |
[
"Old games are built on old platforms and need to be re-engineered to work on modern platforms. Game devs do release old content all the time. You can go on your phone right now and download a ton of Square Enix's old games that have been ported to Android and iOS, but there has to be a financial incentive for them to do it."
] |
What really are radio waves and do they travel at the speed of light?
|
[
"They're a form of electromagnetic radiation, like xrays, infrared, microwaves, ultraviolet, and visible light. They do travel at the speed of light, as they *are* light. You can't see it, however, because it is not at a wavelength that stimulates the rods and cones in your eyes."
] |
[
"Because speed does not 'add up' exactly like we think it does. Let's say you are on a train going 100 miles an hour. You have a model train on a table on that train. It's an expensive model that can itself go 100 miles per hour. You and I, from simple grade school math, would figure that the model train on the real train would have an actual speed of 200 miles per hour. Right? Well, it doesn't! The actual combined speed ends up being 199.9999999-ish miles per hour. The WHY of this is more complicated, but it's one of the things Einstein and the folks of his time figured out, and every test we've ever run proves his calculations right. The same not-quite-adding-up effect will happen to those gears."
] |
why does cold water taste better than regular water?
|
[
"It's just a cultural thing. The Chinese prefer to drink hot water. If there are contaminants or bad-tasting substances in the water, though, it'll taste better cold simply because you'll taste it less."
] |
[
"[This](_URL_0_) previous thread explains it as [entrainment](_URL_2_). When changing the diameter of your lips, the airflow is subject to the [Bernoulli effect](_URL_1_) where it speeds up. When the air moves faster, it draws in more surrounding air which is cooler than your body temperature, thus making it feel colder."
] |
How do animals/insects develop patterns that match their surroundings? (e.g. moth with what looks like branches on its wings - how did the moth's genes "know" what a branch looks like?)
|
[
"By having the animals/insects who stand out get killed off. Think about it like that: The only ones left alive are the most camouflaged specimens. When they reproduce, there’s a chance they produce a better-camouflaged offspring. Those who stand out the most will either get eaten or starve to death due to their ostentatiousness, leaving only the most camouflaged specimens. Rinse and repeat."
] |
[
"It's all up to the programmer. They write some arbitrary \"fitness test\" to assign a score to each member of the current generation & then breed them. Breeding, likewise, is up to the programmer. They figure out a way to represent attributes/parameters of the algorithm as numbers and then \"shuffle them up\" while possibly adding in some \"mutations\" to get variability. In this case, score is a pretty obvious fitness test & [it looks like they used a relatively simple neural network](_URL_0_) to model behavior. This means that the numbers would be the weights of the connections in the network."
] |
the territorial boundaries in Antarctica
|
[
"Many of the claims generally match the longitude range of the countries making the claim. For instance, because Chile and Argentina share similar longitudes, they also claim overlapping wedges of Antarctica. Great Britain claimed the peninsula based on past exploration, so that overlaps with Chile and Argentina. The unclaimed wedge mostly overlaps with the longitudes of the US, which has not [yet] made a claim. Under the Antarctic Treaty, all the claims are held in abeyance (not formally recognized), which is probably a good thing because the Chileans, Argies, and Brits don't always get along so well. If the treaty ever expires, there's going to be a scuffle."
] |
[
"Because Clarkson's Porsche had 'H982 FKL' written on the license plate, and Argentinians though it was a provocation because Argentina lost the Falklands War that went down in 1982. _URL_2_ _URL_2_"
] |
how a penis can get erect, maintain proper circulation without increasing the blood pressure appreciably in the rest of the circulatory system?
|
[
"The arteries leading into the penis dilate, resulting in an increased profusion of blood. The veins leading out of the penis are constricted by muscular action, restricting the ability of the blood to flow back out of the system into the body at large. This also explains in part how a priapism can be dangerous, as you can get oxygen-starved tissues."
] |
[
"When the pen isn't in use the ball in the tip is pushed outward by the ink's pressure on it. When you apply it to write it pushes the ball back into the cone, allowing ink to flow through channels cut into the surface of the cone part of the tip and onto the ball and thus the paper. _URL_0_"
] |
Doctors sometimes give Activated Charcoal to patients. What is the significance of the "activated" part; what is being activated?
|
[
"The name activated come from the fabrication procedure. In the fabrication process you have an \"activation \" phase which consist in pyrolysis under nitrogen or argon atmosphere with an other compound, like water, CO2, acid, sodium hydroxide... This activation phase will create surface/porosity on and in your charcoal. This porosity allow activated charcoal to absorb some compound. I hope my explanations were clear (and my English not too awful)"
] |
[
"When playing Blackjack, there are a set of odds for how much a player can be expected to win based on how the House(the casino) plays and the likelihood of a player getting Blackjack. As the game progresses, more cards are shown, leaving less than a full deck inside. In Blackjack, having a deck full of high cards is better for the player. So, if a lot of low cards are played at the beginning, then that deck has better odds than a deck that had a lot of high cards played in the beginning. This advantage gets to be so high that the House loses its natural advantage and the player effectively makes money on every bet with this deck. People count cards as a way to track when this happens. EDIT: I accidentally a letter"
] |
Why do people twitch and jerk just as they are falling asleep?
|
[
"I read somewhere that a part of the brain sends a signal out to see if the body has been effectively shut down by another part of the brain, so the brain can transition fully into sleep mode. If you're fully 'shut down' the signal doesn't cause a limb to respond. If you twitch, the part of the brain which controls limbs hasn't been shut down properly. Further pulses get sent out again until no twitch response is observed and then the brain knows its SLEEPY TIMEZ. Or did I dream it?"
] |
[
"I read an article a somewhere that said it was do the the \"roughness\" or randomness of the noise. As the fingers nails catch and slip it produces random variances in the amplitude and frequency of the noise. Our brains find the signal unpredictable and that somehow causes it the view it as a danger. There are also some theories that it sounds like a scream and it's an evolutionary reaction to potential threats"
] |
How can a researcher know they've created graphene when both graphene and graphite are nothing but carbon?
|
[
"You can use any of a number of imaging methods to look at your sample, for starters. Pop it in an [AFM](_URL_3_), [SEM](_URL_4_), [TEM](_URL_0_), [STM](_URL_1_), something that can look on the atomic level, and you can poke around to know if you've got single sheets (for example, note the flat spaces to the sides of the graphene in several of those images). It's worth noting that graphene IS graphite, just that graphite is enough layers stacked up that you lose the fancy properties of the 2D material. You could also have a look using x-ray diffraction and find [different results](_URL_2_) for graphite vs graphene. A friend of mine is doing undergrad research with epitaxial graphene, so it's not like it's a super-exclusive club of researchers. It's a huge field at the moment. I can try to prod him to pop over if you'd like to know more."
] |
[
"All vertebrates are craniates, and all craniates are chordates. Chordates have 5 things you need to look for. - Notochord: Pretty much the spine before it developed into a spine (which happened when vertebrates evolved) made of cartilage - Dorsal neural tube: Equivalent of spinal cord - Pharyngeal slits: Known as gill in fish, used in filter feeding in earlier organisms, we lose them during growth but they are visible early on in development - Post anal tail: Exactly what it sounds like - Endostyle: Traps food that passes through the pharyngeal slits by producing mucus in the early organisms, it's the thyroid gland in us Craniates are chordates that have a skull. Vertebrates are craniates that have a *bony* backbone, not just the cartilaginous one that is present in chordates."
] |
Sometimes when we sleep, we wake up feeling very refreshed and energized. Sometimes we wake up feeling very sore and stiff. Assuming that the same amount of sleep was needed in both instances, why do we sometimes wake up sore and groggy?
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[
"you actually \"deep\" sleep in ~1.5 hour cycles. if you wake up in the middle of one of those cycles you'll feel groggy. if you time it to wake at the end of those cycles, you'll feel more refreshed. in your scenario where you've slept the same amount of time, i'd guess something was disturbing your deep sleep, but not enough to \"fully\" wake yourself up. there are some alarm clocks/apps that monitor your sleep (via movement) and will wake you up when you are not in a deep sleep cycle."
] |
[
"We also don't have as sensitive senses as dogs do, so we can't wake ourselves up at the slightest sound, touch, smell, change in light or taste. You'll notice that while the dog nods off easily, he'll be awoken by certain things that won't wake us up. Not to mention that they sleep when the need/can, whereas humans usually sleep when we should. ie A dog that just lives around the house and is nothing more than a pet will more likely nap throughout the day and night, occasionally getting up to make sure everything is alright. Whereas a work dog, such as a search and rescue dog, or a hunting dog will stay awake while they are working and sleep when they aren't. Much more similarly to humans. The reasons dogs can sleep in much shorter spans is because their sleep cycles are shorter. This means they sleep for a shorter amount of time, get up, do their stuff and then fall asleep multiples times a day, whereas we only sleep for one extended period, with a possible nap."
] |
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