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Is there any actual scientific basis behind the multi-universe theories, or is it just smart speculation? Multiverse theories spawned from string theory as well as being a possible resolution to wavefunction collapse. String theory cannot be proven but it also hasn’t been disproven yet. It’s important for string theory that Lagrange invariants stay invariant through experimentation. The problem is that multiverses are untestable, so they fall outside of the realm of science.
why do different languages (English, Russian, Thai) use different alphabets but use the same symbols for numbers (1,2,3) Short answer: Arabic numbers became really popular among mathematicians and merchants and spread around the world. It was easier for everyone to stick to the same system.
What do the police do with the money after a big drug bust? conflict of interest?
whats the difference between soap and body wash? Bar soap is a detergent (cleaning) chemical that remains in solid form at room temperature, and doesn't immediately dissolve when put in running water. Body wash is also a detergent, but its chemical form is more like shampoo in that it's pre-dissolved in a small amount of water. Because it's already dissolved, it's more convenient in a number of ways, but less convenient in some others. The conveniences are that it can be spread and turned into bubbly foam much more easily than soap can, and manufacturers can load it up with additives like strong scents and ingredients like skin conditioners that a bar of soap just can't hold. And because its packaging is permanent, you don't have to deal with grody, slimy hair-covered bars of soap that have gone a little soft and are shared with other people. But the compromise is it's more expensive as a liquid to package and ship, and you go through it a lot more quickly due to the water content so you end up buying a whole lot more.
How does clicking a box to confirm you're not a robot stop robots? The captcha isn't checking that you clicked the box. But how you clicked the box. What was the path of the mouse cursor movement. What was the delay in movement. What was the speed of the movement. What were the initial and ending coordinates Applying heuristics, it can give a confidence level if it matches any known bot clickers. And your data is compared to all other human and bot clickers to see if you are a bot clicker
why do voices sound high pitched when sped up? This has been answered accurately already so I'm gonna try to do a better job of explaining it to a 5 year old. When you talk, there are "strings" (not actual strings, more like folds) in your neck called vocal cords that make the talking sound. The faster they move (or vibrate), the higher the sound they make. Children's voices sound higher than adult voices because children's vocal cords aren't as big, so they're able to vibrate faster and make a higher pitched sound. The same thing happens if you take that sound and play it even faster. You're artificially making the vibrations of the sound move faster so it sounds higher pitched. This is true of any sound, not just voices. : In case I simplified too much... here's a longer answer for anyone who wants to go a bit deeper, or who wants to complain about slight technical misunderstandings of what my simplified explanation meant: When vocal cords are smaller they naturally vibrate faster when air is pushed by them, which means the frequency of the audiowave pattern they produced gets repeated quicker. That's the frequency, which determines how high we hear its sound. The faster something vibrates, the higher pitched it is. You do the same thing when you take a recording and run it faster. You increase the frequency of the audiowave pattern, so the pitch gets shifted up. So the "Explain it like I'm 18 and just haven't taken physics for some reason" answer is that in audio, pitch = frequency, and frequency = wavespeed / wavelength. If you speed up the wavespeed without changing the wavelength, you get a higher frequency, which equals higher pitch. But that answer had already been given when I wrote this, so I went for something a little more illustrative, and a lot of people seemed to find it more helpful. For accuracy I adjusted some words and added some notes in parentheses. I originally talked about the length of the vocal cords instead of just overall size, which, while accurate, is not AS accurate, and just seemed to confuse the issue.
If camera lenses are circular, why do are pictures come out as a rectangle? Lenses are round because they're easier to manufacture that way and it means they can be rotated to for zoom without that affecting how the lens works. This just gets the light in and focuses it. The light falls onto a light sensitive detector or film which is rectangular. In both cases this is because that's the preferred format for pictures...but also because it's easier to make (for film) and maximises the space used for capturing a picture (both film and digital).
Why do we perceive ourselves do differently when looking in the mirror or when being on camera & which is the more accurate with regards to how we really look? Neither are correct. Camera lenses have different focal lengths that can heavily distort the picture. 135mm should be "most" accurate but it depends on a lot of things. Mirrors then seem like they should be more accurate, but mirrors have their own distortions. If a mirror is not perfectly flat it's going to distort some. Most older mirrors (like the ones you probably have at home) bend slightly from top to bottom making you look a little fatter. There's probably some kind of setup you could create with perfectly flat mirrors to give you a perfectly accurate view of yourself but that'd be more effort than most people are willing to consider.
If inside my house is 60° in the summer it feels nice. If it's 60° in the winter it feels cold. Why? The real answer is relative humidity (moisture level of air), not all 60 degree temperature is equal, you are constantly losing moisture through your skin, and for that moisture to boil off (evapourate) it saps energy from you, cooling you down. In the summer, there is a higher relative humidity in the air, slowing this process, if you heat yourself up enough, you will noticeably sweat as this moisture is having a slow evaporation process In the winter relative humidity is drastically lower, causing this process to almost immediately draw moisture off of your skin cooling you rapidly, therefore making you colder, even though the air is still 60 degrees. This is more common in older homes that don't have a vapour barrier, if you install a humidifier, (or even have a hot shower or two without running the fan to raise levels) you may see noticeable improvements.
Why does the pavement look wet on a hot day, while driving? What's you're seeing is called heat haze Light from the sky at a shallow angle to the road is refracted by the index gradient, making it appear as if the sky is reflected by the road's surface. The mind interprets this as a pool of water on the road, since water also reflects the sky. The illusion fades as one gets closer.
How come Venezuela is in such a poor state if it has nearly 300 Bn barrels of proven oil reserves? All oil producing states too a hit when the price per barrel tanked. Venezuela in particular has a few problems. Theirs is high in impurities, which increases refining costs. Plus they were selling it for pennies on the dollar to their own citizens as well as key allies like Cuba. Venezuela's is what would be classified as a "banana republic". That is a country which is nearly entirely dependent on a single industry. Over 93% of their economy is tied to oil. Any shocks to this industry can have a catastrophic ripple effect. Adding to the problem is that Venezuela is not agriculturally self sufficient. Most of their food has to be imported. These goods are purchased from suppliers using US dollars, but are then purchased by citizens with the local currency. The Bolivar is not only worthless, but extremely volatile. The country's inflation rate is expected to reach 481% this year. If you started with an item that costs $10 on January 1st, it will cost $48.10 by December 31st. When you consider the average wage is $20 a month, a nearly 5 times jump in price is crippling. Stores are taking in less money than they paid for their stock, which means they have less money to buy new stock, and so on. Which is what's causing shortages. Those who can get their hands on US dollars instead chose to buy goods on the black market. Criminals are taking big time advantage of the social breakdown, which is why the murder rate has become so high. On the government end, corruption has been running rampant for years now. Maduro and the other heirs of Chavez's Bolivarian Revolution are desperately trying to cling to power. The government also owns a big portion of the failed oil sector. Maduro will keep trying to blame capitalists and the US, but that will only go so far. Things aren't likely to end well for him. Incidentally, this is also likely the reason behind Cuba choosing to negotiate with the US government. The island nation was heavily dependent on Venezuelan economic and political support during the Chavez regime. Havana doesn't want to fall back to the dark ages of the 1990's after the Soviet Union collapsed.
ELI5:How do scientists measure the speed of light? With a rotating prism. Start with two observatories on mountain tops (a good place for observatories) that are far away from each other, but still close enough that they can see each other. Being on mountain tops helps to see over all of the stuff in between them. Measure how far apart the observatories are. Carefully put up a mirror at the far observatory so that the other observatory can see itself in the mirror (very far away, but they have telescopes in observatories for that.) From the near observatory, shine a beam of light at the mirror at the far observatory. Thanks to the mirror, you can see your own beam of light shining back at you from the far observatory. Now take a prism, but not the triangle prism that makes rainbows, no. Use a prism with an even number of sides, like a square or an octagon. This way you can look straight through the prism from one side and out the other. Put the prism in the beam of light. If you hold it perfectly straight, then the light will still shine all of the way to the far observatory and back, but only if it is straight, not crooked. Now spin the prism. Use an electric motor so that you know how fast it is spinning. As the prism spins, when it lines up with the beam of light, a tiny flash of light will go straight through and to the mirror at the far observatory. But by the time the flash of light gets back, the prism will have kept spinning and it won't be lined up with the light beam any more. But if you speed up the motor that is spinning the prism to the right speed, then the little flash of light that gets through the prism and reflects back from the mirror will arrive at exactly the right time to go through the prism when it lines up with the light beam the next time. So if you know how fast the motor spinning the prism is turning, and you know how far away the mirror at the far observatory is, then you know how long it took for the little flash of light to travel that distance. Distance/Time = Speed. And that is how you measure the speed of light.
Why did fully wireless earphones/earbuds take so long to reach the market, when those quirky bluetooth headsets have been around for so long? A big part of the problem was and still is that the buds need to receive a stereo signal at exactly the same time. The phone being in your pocket on one side of your body is enough to throw that off. http://www.businessinsider.com/apple-airpods-delay-wireless-earbuds-technical-issues-2016-12
What does salt do to snails? Snails and slugs have an outer mucous membrane with water-based slime on the outside, The saltdissolves in this slime, forming a highly concentrated solution of salt. ... As a result, they shrink for loss of moisture, and a pool of salty water forms around them. - Quora
Why is it that when we are enjoying ourselves that time seems to go by quicker? I think one of the main reasons is we get lost in what we are doing and don't think about the time passing, but when you're going through something you don't like you are constantly thinking about the time and looking at the clock
Why do men become bald-headed more often than women? Testosterone, while it is responsible for secondary sex characteristics such as body hair growth and the deepening of the voice, is also toxic to hair follicles on the top of the head based on its reaction with some of their androgen receptors. Based on genetics and cell type, different parts of the body respond to testosterone differently.
ELI5:Why is black pepper nearly as universal as salt as a seasoning for savory food? Peppercorns are easy to transport and keep fresh, which mattered a lot more in the Middle Ages to 1940. Because it was one of the few spices that was widely available, it became a staple in recipes.
Why is it that, on electric fans and other appliances, the order of the settings is OFF, HI, MED, LO? The motors need a lot of power to start from a stop position. Low power sometimes isn't enough power so the best choice is putting it on high as the first step.
Why do places like India and China have such a higher population than the rest of the world? Rice, rice, baby. Of all the crops available to the preindustrial world, rice produces the most calories per acre. At the same time, rice is more labor intensive than most crops. That means rice can both support more people per acre, and more people per acre to farm it. If you have a lot of land suitable for rice, you are going to have a great population density than your barley growing neighbors.
What's the benefit of displaying a menu price without tax included? Plenty of countries include the tax in the final price but the U.S adds it separately. If your competition doesn't show the price tax-included, it makes their products seem less expensive (even if they're the exact same price or a little higher). In addition, it allows advertising to be done for prices across boundaries where the tax rates might be different (such as across state borders - or sometimes even within a given state). It also means any changes to the taxes in an area doesn't mean you suddenly have to reprice everything manually. It also lets you easily see exactly how much tax is being paid by looking at your receipt, instead of just assuming that the company is paying the sales taxes properly.
How could anything have "happened" to cause the big bang if time and space did not exist before the big bang? That is a great question. Unfortunately - through no fault of your own - it doesn't actually make sense. Our models don't go back far enough. Get even too to the actual big bang - let alone it - and time itself ceases to make sense. Under the models that we have available, it is to draw meaningful conclusions about the Planck era beyond some very broad, very vague generalities.
What is the difference between strategy and tactics? A strategy is a plan, a tactic is an action. In battle terms, your strategy to defeat a town might be to starve them out, and your tactics would be blocking their supply lines or spoiling their food stores. That being said, I think that they're basically interchangeable in everyday language. There might be an implication that a 'tactical' decision is something done in-the-moment to achieve immediate ends, while a 'strategic' decision is part of a longer-term plan.
Why do people look so distinctly different in photographs than they do in real life? Yer not alone in askin', and kind strangers have explained: ELI5:Why do people look better in person then in pictures? ELI5: Why do some people look unattractive in photos, but look attractive when in person? ELI5: Why do I look so much better in the mirror than I do in pictures? Why do I look handsome on the mirror, but ugly in photos? ELI5 Why do we look different in a mirror and in a photograph? ELI5: Why do I look different(or better) in mirrors than I do in pictures or videos? ELI5: Why do we look different in reflections and in photos? ELI5: Why do I look different in pictures of me and what I see in the mirror? ELI5: Why does one look ugly on camera, but handsome in the mirror? ELI5: Why do I look pretty in the mirror but horrible in photos? What makes someone Photogenic? ELI5: is there a reason I like how I look in a mirror but hate pictures and videos of myself?
How do manufacturers of vehicles make car keys that are unique such that not 1 car key is identical to the other? Certainly with normal keys, it's more than possible that there do exist keys that will open more than one lock, but the whole security of a lock and key is that you don't know that. Or put another way, if you were to find a random key at the side of the path one day and pick it up, would that make you any more likely, in the grand scheme of things, to be able to get into the house it came from? No, because you don't know which house that is. Could be any one of millions of keyholes. Cars are the same. Odds are with the number of cars in the world, there are certainly keys that are duplicated somewhere, but how do you know where and what cars? You have no way of knowing.
Why isn't there dry human food with all the needed essentials like there is for pets? Because we don't want it. There is no demand for it and we prefer a varied diet. There is soylent which is a smoothie type thing which is essentially all you need to eat. It claims to have all the nutrients, fats, calories and whatnot a human needs to be able to survive on it alone. It exists, but it isn't exactly revolutionizing the way humans eat.
why do people get the munchies when they smoke weed? Hunger is a side effect of the drug, my man. THC binds to two receptors in the human body, creatively named cannabinoid receptors 1 and 2 (CB1 and CB2 for short). CB1 is located in several places throughout your body, including your brain and your GI system. When THC interacts with CB1 in your brain, it has psychotropic effects including euphoria (it gets you high). In the GI tract, CB1 normally helps to regulate food intake, so when THC meets the receptor there, it causes you to feel hungry.
How hushing came to be the sound we use when we want people to be quiet. I always wondered about the same thing and quite recently I discovered that the hushing sound is the most common sound you can make with your mouth to calm down a newborn baby: they naturally calm down when they hear vibrations and white noises. I wouldn't be surprised it just came out from this: a lot of pèarents who are used to hush to silence and calm their babies and simply go on doing that when they grow up, and, bang, you create the international conventional sound for silencing.
why can't there be cars that look as cool as lambos, but with cheap components to make them as cheap as a regular Honda A lot of comments are missing another factor: Car companies don't their cheap cars to cannibalize sales of their high-end sports cars. Let's suppose for a moment that they are in fact able to make a Dodge Dart look like a convincing Ferrari without increasing the cost. Further, let's suppose that people wouldn't heap disdain on the fancy-looking Dart for being a shitty car posing as a nice one. Both of those things are probably iffy prospects, but not outside the realm of possibility. That would be a great thing for Dodge, right? Except, Fiat owns both Dodge and Ferrari. So what they've actually done here is to replace some of the sales of a $2-400,000 car which probably earns them $50,000 or more in profit, with a $17,000 car that earns them probably closer to $200 profit. These companies aren't to compete with each other. Edit: As several have mentioned, I was probably overestimating the profit margins on the low end. Honestly the correction only makes this logic more compelling.
Why do we tend to only get thunderstorms in the evening or night, why are they rare during daytime? They happen most when there is a temperature gradient. During the day, the temperature is hot everywhere and night, the air higher up cool rapidly. The air lower down is still very hot. this leads to clouds forming up high and having a large electrostatic potential
Why do we feel the urge to go to the toilet more and more the closer we get to the bathroom? Classical conditioning. I'm blanking on the technical terms to describe things but whatever. (Most) every time you go to poop/pee, you do it in a bathroom, therefore your brain pairs the urge to poop/pee with the surroundings of a bathroom or toilet, they go together and if you're doing/in one, you're at a high chance of doing/being in the other. Your brain therefore picks up on the pattern. From then on, whenever you see a bathroom, you will get a little urge to do the dirty. If you actually don't have to go, fine, whatever, it's not noticeable, but if you do already have to go then that urge is pretty handy to help you be ready to let 'er rip once you're there. The sight of the bathroom becomes a stimulus to tinkle/shart, the bell to your Pavlov's doggy drool. Same thing goes for people who smoke when they drink, often they need to cut down their drinking to help them quit cigarettes. Same with when you see good food and start to drool or you see a meth lab and think, mmm, maybe I should do some meth.
How did people with poor vision function in society before eyeglasses were invented? They would do the things that they were capable of doing. Before modernity few people could read so up close detailed vision was only needed if you were a craftsman general functions could be done without having perfect vision. Before modernity great long range vision people did not drive a lifeless vehicle. Horses will avoid general hazards and do not move fast enough that having great long range vision is needed by your average person. It is only those who hunt with ranged weapons. If you have bad long range weapons you do other things like tend the crops. If your visions is so bad that you are basically blind you were cared for by family/friends, begged on the street, or died.
How are genders different than sexes and what do many different genders mean? Not trolling, just can't understand. Don't turn this into a fight. Since there is a lot of overlapping terminology I'm going to use "male" and "female" when I'm refering to sex and "man" and "woman" when refering to gender. The definitions I'm going to give for the different genders aren't set in stone and are debatable. But, it's a good entry point. Sex is a biological trait that is related to our genes and hormones. In our DNA we have what are called sex chromosomes "x" and "y". Generally XX chromosomes create a female sexed person and XY create a male sexed person. There are other combinations, sometimes with more than two. In addition, because of other genetic effects hormones can override these chromosomes and create other sex traits. Arguably male and female are the most common, but intersex people of varying sorts aren't particularly uncommon. Gender is how we as a society expect the sexes to behave in that society but also to some extent how a person wants to interact with society with regards to their sex. So, if we looked at the US in the 50's that might mean, women have long hair. Men had short hair. Men went to work. Women stayed at home with the kids. Men liked cars. Women liked cooking. Etc. etc. etc. The usage of new gender words is to try to express the feeling many people have that their gender is either more complicated or innaccurate than the default society wants to give. The different new genders express similar but somewhat distinct ideas. People who are genderfluid tend to find that they will sometimes strongly identify with certain gender roles at different times. So a person who might love to wear very masculine suits and very feminine dresses may be genderqueer. Genderqueer is someone who finds that the normal expression of gender doesn't quite capture how they feel. They don't quite see themselves as men or as women but something amalgamated. Gender neutral is someone who sees themselves as having less gendered content. Often times gender neutral, genderqueer and genderfluid are thrown around as interchangeable. They aren't exactly. But for many people they effectively are so similar and used in such a variety of ways they all end up roughly meaning "not quite men not quite women". All of this is made more complicated by the fact that liberal socities are generally trying to break down gender roles as it is. While there has been great progress compared with say, the middle ages, there is still a TON of assumed gendered behavior that just doesn't capture people's lived experiences. I'm a little hungover so let me know if I need to do any clarifying! EDIT: Just to re-iterate a point. Sex is also more complicated than a lot of people are saying. There are more sexes than simply male or female so it's not just you are born male or female. Follows is a link with some info on intersex (which are those people who are born not exactly male or not exactly female). http://www.isna.org/faq/what_is_intersex EDIT 2: HOLY SHIT! Reddit gold! Thank you anonymous benefactor! This is my first ever reddit gold. I also passed the New York bar this week. It's been a good week (the reddit gold is better). I want to quickly address a few of the "biological" points that came up in this thread and why they don't really answer the question. Someone pointed out that standard female brains tend to be smaller (which for those MRA people out there has absolutely zero correlation with intelligence), men usually have more testosterone etc etc. This is true. But notice how I had to use words like "standard" and "tend" to. It is not always the case that if you take 1 woman and 1 man they will always have relative differences based on those factors. Some women have bigger brains and more testosterone than some men. This then fails the necessary 1 to 1 requirement of a definition. For example, if I said a chair has 4 legs and then showed you one with 5 legs or three legs (or none, like a rocking chair on skis), you would have to say well it's not a chair or my definition is wrong. In this instance, I think using those points may help us understand trends and tendencies (but probably not) they don't help define gender or sex. Again I want to point out that sex is something on the biological level and unless you have a habit of DNA testing all of the people you know, you won't ever meaningfully interact with a person's sex. Because you can only ever interact with a person who has been socialized you will always interact with their gender expression. These words help more than 1% of the population. And even if they only help 1% of the population, in the USA alone that is 3 million people. That is a lot of people. I admit, learning a few new words is an inconvenience and takes some processing power (you have to read my whole post). Once you've read the post. You now know the words and can't make the argument that you will be harmed by using the words. You already know them. Seriously though, the inconvenience is minuscule on a societal level to grasp new words. I also want to point out that the idea of non-binary gender is not new. Many cultures have had third and fluid genders. For example, North American Native Americans (exactly how many tribes is currently under debate) who had a concept of two spirits and had 4 different gender categories. This idea of third gender and gender non conforming is even in the kama sutra. Plato's Symposium mentions a creation myth with Male, Female and Gender Neutral characters. EDIT 3: One more clarification. The reason individual gender expression and letting an individual pick their own gender is the best solution is precisely because gender on a social level is a weak concept. As many people have accurately pointed out women can wear pents, men can have long hair etc. etc. Agreed! That's why things often associated with gender aren't defining, merely associated (in fact many of the things often thought defining of gender in our times were different in other times, Pink used to be a boys color (it was like blood and men were bloody), and in the Middle Ages in Europe women were seen as the sexual predators and men were the innocents who needed to protect themselves). Since pretty much anything associated with gender isn't a 1 to 1 it doesn't define any gender. Therefore, there is no good way to make a call as to who is or isn't a particular gender on a macro level. Therefore, the only way to accurately sort people is to just let people sort themselves.
Why do well established brands (eg. Coke) still market themselves so aggressively? What do they stand to gain when they're already a household name? All that marketing is how they continue to stay a household name. These aren't video game achievements where once you reach them, you never lose them again. If these established brands stop marketing themselves, they will start losing market share.
What causes time dilation ? I have a very brief understanding of time dilation, but can someone please explain the cause behind it. A difference in relative velocity, or gravity (which the STR/GTR tells us are equivalent to each other). As to what this looks like, and how it works, it's not really ELI5 territory. The bottom line is that it's derived from the two postulates: The laws of physics are everywhere the same, and lightspeed represents the "speed limit", or more accurately, barrier. Once you understand that, it starts to make a bit of sense a la: http://www.pitt.edu/~jdnorton/teaching/HPS_0410/chapters/Special_relativity_clocks_rods/index.html
The Monty Hall Problem I understand the basic math of it, but I don't see its practical application. In the real world, don't you have to reassess the situation after 1 of the 3 doors has been revealed? I just don't get why it would make real - world sense for you to switch doors. Thinking of the problem as 100 doors instead of 3 is what made this for me. With only 3 doors, I was discounting how Monty's outside knowledge of where the goats and car were was fundamentally changing the problem. Expanding the example made the mathematical logic of switching doors much clearer in my head. Thanks for all the in-depth answers! To understand it in a more "real world" sense, I think it helps to get rid of the standard trappings of the problem. The below, as far as I know, is mathematically the same, but makes it clearer why it makes sense to switch. You are a superhero standing watch in a crowded train station. A stranger comes up to you, and asks you to pick, a person, at random, out of a crowd of thousands. We'll call your pick person A. The stranger then tells you that they are, in fact, The Stranger---a math themed supervillain. They go on to explain that one of the people in the crowd is their agent, and has a bomb that will blow up the city. Seeing the worry in your eyes---and a total lack of thinking about math given the crisis—the Stranger says that they will even up the odds a bit: they will eliminate all but two of the people in the crowd who might be carrying the bomb: the person you picked at random without even knowing what you were doing, and person B. The Stranger guarantees that one of these two people has the bomb, which will detonate in a few seconds So, in that case, who would you think has a better chance of being the bomb carrier, the supervillain’s pick, or your random pick? If you only had time to disarm one of them, would you go for person A or person B? I think that this makes it clearer why you “switch” rather than just, say flipping a coin. The odds that the bomb is on your person are a random chance from the original cast of thousands, and is truly random. The odds that the supervillain’s person has the bomb are obviously higher, since they MUST have the bomb if you’re original choice was wrong, and your original choice only had a one in several thousand chance of being correct.
ELI5; Why does paper get weaker when wet? This goes for toilet paper, 'normal' paper etc. Edit; As pointed out, I'm looking for the mechanics of why this happens as opposed to a design choice (by toilet paper manufacturers etc.) I'm not actually 5 - I'll let it slip since I hit 6 last week.
How do ISPs work? Something I've pondered for awhile. How do ISPs work? I know the internet basically works by sending a signal from my PC to another PC (Read: A server), but where do ISPs factor into all this? How and why do our signals have to go through them? I explained this to my 6 year old like two days ago, that seems close enough: Every device that connects to the internet is part of a network, the computer in your house is part of the local network in your house, the website you're trying to reach is on a computer that's on another network in someone elses house (or business premises). But for those two computers to talk to each other and show you their website, the two networks need to talk to each other. So, your ISP has their own network. You connect your network to theirs, then they connect their network to someone elses, then they'll connect on to someone else. This keeps going, all of the different networks come together making paths that let you get from your computer at home to the one that has your website somewhere else. ISPs provide the door out to the bigger networks from your house. The internet is just lots of networks coming together and ISPs let you join that network. Obviously it's not as straightforward as that. But that kept the 6 year old happy, covered the basics and makes a good starting point I think. My younger brother never quite understood it that way though. So when I explained it to him I went with this: You want to send a parcel to someone in another city. But it's huge, needs a truck and has to be collected from your door and delivered to their door. It'll go down the road outside your house, then it'll join the bigger road at the end of the street, then it'll get on a highway and head to whatever city it needs to go to, come off the highway on to the mail road, then back onto their street and finally down the road to their door. The only problem is, you don't have a road to your door. So you call up your ISP, they come out and build a road that lets you get from your door to the bigger network of roads that'll let the parcel go to where you're sending it.
Jupiter's core is said to be "Liquid Metallic Hydrogen/Helium". How can hydrogen and helium be metallic? I think I might understand how at extreme pressures hydrogen and helium can't be gaseous despite the temperature, but what does being metallic mean? How is that possible? In this case "metallic" is in the physics sense of the word, in that they have high electron conductivity, high thermoconductivity and high density. It has to do with the EXTREME pressures involved, which causes hydrogen to break down from its normal molecular (H2) form and become atomic. Scientists were finally able to create it in the lab earlier this year. Previously it was theorized that it would take pressure of 25 gigapascals to make hydrogen metallic, in the end it actually took 495 gigapascals. You can read more about the discovery Here
Why didn't the indigenous populations of the Americas spread any disease to the Europeans? Why was the spread of disease so one-sided? The rate of disease and rate of evolution of new diseases are related to the population and population density of a group. The more people there are the more closely they live together, the higher the chances of bacteria or viruses evolving to be harmful to that population. There is also a greater chance that the disease will both spread through the entire population and that some of the population will survive with their own adaptation that helped them survive the disease (immunity). In small disperse populations, diseases are less likely to evolve since there are simply fewer hosts and hence fewer bacteria and viruses to undergo mutation. Native Americans lived in small groups which were generally separate from each other in a large continent. Europeans had large cities of hundreds of thousands of people in high density with poor sanitation and often traded with each other. So it was far more likely that more diseases would evolve in densely populated Europe than in sparsely populated North America.
How come when something really hurts our feelings we can feel it in the pit of our stomach and chest? There was a study published in 1942, where a man with a fistula (hole in the body) had a clearly observably stomach and colon. The stomach and colon would be white when the man was depressed, and turn red when angry. There are a lot of things going on down there, butterflies, stomach churning. In cases of extreme stress, the body needs to be ready to lighten the load (poop your pants with fear) and divert blood from the tummy to the limbs for running away. the study https://books.google.com/books?id=JaQauznPoiEC&pg=PA48&lpg=PA48&dq=stomach+changes+color+with+emotions&source=bl&ots=EDEe9z3lEj&sig=_toKsMeFvBf_WvbR4y1daEGdeFg&hl=en&sa=X&ved=0ahUKEwj5k4OFtPPTAhXFy1QKHbkGARgQ6AEIUDAH#v=onepage&q=stomach%20changes%20color%20with%20emotions&f=false
What keeps me from rolling off my bed at night? If I sleep alone in a Queen size bed, for example, I could theoretically fall asleep on one side of the bed and wake up on the other side. But what keeps me from rolling off entirely? You never go completely to sleep at night. A small part of your brain never sleeps and always watch out for dangers. It is this part of your brain that will listen to your alarm and make you wake up. It is also making sure you do not fall off the edge of the bed.
Digestion takes about six to eight hours through your stomach and small intestine. Food then enters your large intestine for further digestion. What happens when you eat something bad, and all this is reduced to minutes? So your bowels are like a long train track and your food is like a set of cars on the track. Transit time between Point A, your mouth, and Point B, the chute, is a bit flexible but normally operates on a regularly scheduled basis. When you eat, you put cars on the track and send them to Point B. As these cars go to Point B, they lose passengers (nutrients) at various points in the thin tunnel portion (small intestine). The journey isnt complete and the journey has already altered the shape of the car pretty significantly giving a rusty color. Once in the larger portion of the tunnel, the cars are checked for stray passengers and are hosed down a bit so that transition out of Point B isn't so bad. Sometimes, the train cars park juuust outside the gates of Point B so they can exit at the best time for the operator (toilet). Now, all of this goes fucking nuts when you load a bad set of train cars at Point A. The track sensors located everywhere along the track, detect this alien set of cars and sends a distress call to the Supervisor (your brain). The Supervisor wants to handle the situation without having to phone the Manager (your consciousness) about the craziness on the tracks and also wants to make sure you never know it was on the tracks. It has to make a choice now: send it back to Point A violently and somewhat painfully risking tearing the tracks, or send it to Point B as fast as fuck? Depending on where it's located on the track, it'll choose the best route. Let's use the destination Point B. The Supervisor hits the panic button and puts all the train cars that are on the track (in your body) on overdrive. The tunnels are flooded with water and lubricant to speed all the cars up and get them the hell out of there as quickly as possible. Cars collide with each other, and previously well formed cars are just flooded with water and lubricant that they are just a soggy, shadowy reminder of their former glory state. The Media (pain) hears about the car collisions immediately begins filming live the high speed, flooded train cars out of control. They want to knos how an alien set of train cars were put on the tracks and they want someone to pay for such carelessness. The Manager is just watching the horror unfold on Live TV but cannot do anything to stop it, because the Supervisor was deaf and he had not installed a means of communicating with him after hours in the office. I hope this answers your question. TL;DR when you get diarrhea, everything gets pushed out, one way or another. There are no passing lanes. Source: /u/jiggity_gee
why does scraping scissors against a strip of ribbon create a curled strip of ribbon? This also happens with hair when pinched and pulled. There's a really handy sci show video about this topic. It's due to a force called Yield where a certain amount of force will deform something permanently. But only the outside of the ribbon is deformed and stretched making it curl away from that side https://youtu.be/zsyEMSxN9TM
Why does your heart actually hurt when you're "heartbroken"? If we rule out anxiety from a heartbreaking event (which can and will cause chest pain) the answer is Takotsubo cardiomyopathy , also known as broken heart syndrome. This can also occur when coming good happens and you get too excited (or a heart attack, stroke, arrhythmia from a non cardiomyopathic source, etc.). It causes, among chest pain, acute heart failure, arrhythmias, and rarely ventricle rupture. This syndrome temporarily weakens the heart muscle by thinning the walls of the lower portion of the heart, making it much less efficient. Almost all patients make a full recovery within 2 months of having their hearts literally broken. But to reemphases, when your chest hurts because of heartbreak, it's probably anxiety and not your heart losing the will to live.
ELI5:Outside of academia, who employs modern philosophers and what is their role in modern society? I'm sure some more will come to mind soon, but the first one I thought of: Ethicists. When a company or corporation needs to go through an ethics committee, those people are philosophers. Similarly, before doing any experiments (e.g. in science) you also need to get ethics clearance. Ethics is a big domain of philosophy. Edited to add: Also, I know this is kinda covered by "academia", but the main thing that philosophers do is write papers for publication. Whether it's in ethics, metaphysics, aesthetics, philosophy of science, stuff about personal identity or time travel or whatever. Philosophers are the ones researching and writing about it! (Source: am married to a philosopher).
ELI5:How can so many mobile games get away with clearly ripping off copyrighted material? Games are expensive to make, taking lots of time and money. Good games take more time and money. In the mobile gaming world, I make more money when more people download my game, and I lose money in making the game. Stealing intellectual property from other people and well-recognized brands kills an entire flock of birds with one stone. Now I can get lots of people to download my game because of the brand recognition. I don't have to waste my time and/or money developing assets on my own. I don't need to spend lots of time hoping for my brand to get big. I can just sit back while the money rolls in. On the other side of the house, we have the people who made these brands or assets. They can come after me if they want to stop me from using their work for my benefit, but it costs money to do this. If they are a huge operation and I'm one person, it's probably going to cost them more money to take me down than for them to just ignore me. I'm also not the only one stealing from them. They have tons of little leeches like me doing the same thing. It isn't worth their time to go after all of us, so they focus on the biggest and most egregious ones until it stops being worthwhile. If they do come after me, so what? I take that one app down and put up another one ripping off someone else and carry on my merry way. Rinse and repeat if necessary. If they manage to take my entire company down, I'll just open another business and do the same thing again.
How did Salt and Pepper become the chosen ones of food spices? No it's way more interesting. Salt preserves food (by drying it) and is readily attainable (from the sea). Pepper preserves meat (piperine kills bacteria and repels maggots but is harmless to humans). Over time, cultures that embraced preservatives like this prospered and their cuisine spread. In India, they use a whole different set of spices. In China, there are even two different words for spices called La and Ma (edit see below). One is fiery like capsaicin and the other, referring to Szechuan pepper corn, is electric like a battery on your tongue. It's amazing. side note: people seem really curious about Szechuan peppercorn. It actually used to be illegal in the US but as of 2005 you can now buy it The reason salt and pepper came to grace restaurant tables with all those other spices out there is * At the time that formal dining came into fashion, French culture was influential throughout the western world. Louis XIV was an influential man as the king of France. He didn't like as much salt or pepper in his food but others did so he created the custom of having his chefs put it on the table rather than cooked in. The custom spread and western culture helped spread it all over the world. Edit: black pepper contains piperine not capsaicin. Edit 2: Chinese is hard. La (not Lada) and Ma are more nuanced and appear to refer to different things. La is the word spicy generically. And by region (Hunan vs Szechuan) Ma la refers to the numbing spice (that I described as electric feeling) see the comments below for detail.
How are animals able to retain such muscle mass with a restricted diet yet humans need a constant amount of protein and nutrients to maintain much less muscle? The other factor at play in attaining and retaining muscles is myostatin. Myostatin is a protein (also called GDF-8) which inables/inhibits muscle growth depending on how much of it is present in muscle tissues. For example, Gorillas produce very little myostatin and, as such, are extraordinarily muscular without the need for extensive exercise. Humans, on the other hand, produce much more myostatin and so are less muscular and require regular strenuous exercise to attain significant muscle mass. This is due largely to our ancestors being very well adapted to running long distances. Our less muscular frame makes prolonged exertion possible as we're not burdened by a large amount of excess weight that additional muscle mass would add. A Gorilla is very quick over a short distance but it can't chase you for very long.
Why is 100°F air extremely hot and uncomfortable for humans, while 100°F water is slightly warm and pleasant? I've seen this answered a million times before, but for whatever reason, I can't find more than one post on this subject. The answer is heat flux. Water transmits heat 20 times faster than air, meaning that you would be losing heat faster in water than air. To give you an example of this, watch this video . Both objects are at the same temperature, but the metal in the metal hard drive transfers heat faster so it feels colder than the book.
The controversy surrounding GMO's and why are they so stigmatized. There is no controversy around GM crops outside of anti-science and conspiracy theory nuts. The scientific consensus on GM crops is more solid than on climate change.
What happens when your foot "falls asleep" The simple version is a nerve was temporarily pinched, preventing full feeling from reaching the rest of the nervous system. The nerves that innervate your muscles are different than the nerves that innervate your skin which is why you can still move your foot, despite not having full feeling in the skin.
Why does pornography become unappealing, sometimes even gross, after you have finished "using" it? I have never understood why seemingly the most attractive woman in the world very quickly turns into someone I wouldn't look twice at walking down the street. I read from somewhere else that when we are aroused, it overrides the disgust. But it is over-simplified. Edit: spelling
Why are CGI effects so expensive to produce, when they are a virtual tool, that seemingly only requires software? They require trained artists to use those tools. Paying those artists for the hundreds or thousands of hours of work is the real expense of CGI.
Why are we not using nuclear propulsion in commercial ships? Probably not passenger cruise ships, but I would imagine commercial cargo ships would profit tremendously from nuclear power. So why is it that nobody has even attempted (to the best of my knowledge) to use nuclear propulsion for commercial goals. Is it the fixed cost of installing such an engine? Or is it the government's fear that nuclear material may end up in the wrong hands? It's way, way, , too expensive. The power plant alone would probably be more expensive than the entire lifetime cost of an average bulk carrier. Not to mention the insane mess of regulation that is involved with running a nuclear reactor. Basically, big ships run on bunker fuel, and bunker fuel is ludicrously cheap.
Why do horses that break one of their legs have to be put down? Seems like they should be able to rehabilitate them. Especially if they are race horses and could be used to breed later in life, or potentially race again. who wants the offspring of a lame horse Umm, anyone in the market who understands selective breeding? The lame horse doesn't lose its good genes due to an injury. I imagine they know what they're doing and have the racehorse game down to a science, and as you said it might be inhumane to the horse. But I doubt the quote is a problem in itself.
Why is it hundreds of stars at night can be seen from Earth, but videos/picturs of astronauts in orbit never have stars in the background (it is just black)? stars from ISS For those who would rather just click And my fave so far
Why did roundabout's never catch on in The United States? Quite honestly, roundabouts seem much easier to use and understand than any other basic intersection I can think of. Taking up less space, and requiring less up-keeping, why in the world are they not used so much over here in the US of A? We actually are. Obviously it'll take time, but they recently put a few right by my house and I actually find them incredibly convenient. The down side is that a lot of people just can't entirely comprehend the concept.
In movies that take place during 18th, 19th, and early 20th centuries in America, characters are often depicted as speaking with an English accent. When did American born citizens actually shed the English accent and adopt geographically identifying accents like in the north east and south? Sometimes people write down how things were pronounced. We also get hints from poetry because of the rhymes and meter. (Try reading some poetry from the 17th century. There are a lot of rhymes that don't work anymore.) We can also use the comparative method, which is where you compare modern dialects and deduce what they would have sounded like before they diverged, based on their similarities and differences. This method is also used to reconstruct proto languages that were spoken thousands of years ago. Using a combination of these methods, people have found out what Shakespeare's accent sounded like, which is just before the split between American and British English. Here's a recording of someone speaking in the accent from the time period, around 1600.
How do 'Glow in the Dark' objects work? Does it work the same for all glow in the dark stuff? E.g Glowing wall stickers, Glow sticks, Clothing I'm very tired so I'll give a short winded shitty response but you'll probably get the gist of it. Glow in the dark objects contain a compound (phosphors) that can be excited by light. The compound absorbs the light energy by using it to put its electrons in a higher energy shell. If you imagine the Bohr atomic model with the rings around the center, the electron would be moving away from the center therefore occupying a high energy state. The atoms in the compound then release the energy via moving the electron back to its lower energy state (closer to the middle of the atom) and this energy release is given off as light. What color the light is when it's released depends on what compound is used, and what wavelength/energy value is absorbed/emitted by that compound. So to answer your second half of the question- no, not all glow in the dark objects use the same compound. There's more to it and I'm sure someone will take the time to explain it but that's the simple version
How are there telescopes that are powerful enough to see distant galaxies but aren't strong enough to take a picture of the flag Neil Armstrong placed on the moon? Galaxies may be far away, but they are fucking massive, fucking bright, and not fucking moving. (At least not moving very much from our perspective) The flag on the moon is none of those things. Sure it's close, but it's tiny, dark, and whizzing around damn fast. Also, telescope time is valuable. Most large telescopes are booked every possible minute they can be operating years in advance. Nobody is willing to waste time trying to spot a flag that we already have great close-up pictures of when they could be doing science.
What causes "asparagus pee" and how does it happen so fast after eating it? Short answer is that asparagus contains a natural chemical aptly named asparagusic acid. This acid is broken down by the body into sulfur-containing compounds. Those sulfur compounds smell. This is the same reason rotten eggs smell. And once made, the breakdown products end up in your urine. Because they are highly volatile, they make it into the air as you pee, and float on up your nose! I don't know exactly why it shows up so quickly, but my best guess is just that the smelly compounds are made from asparagusic acid very quickly, as soon as you begin digesting the asparagus. Source: http://www.smithsonianmag.com/science-nature/why-asparagus-makes-your-urine-smell-49961252/ Not an asparagus expert, nor a pee expert. Just googled your question and found a good article.
Why Do We Have Squatter's Rights? What is the argument for them? I've never heard them mentioned in a positive tone. Also, what exactly does the term "Squatter's Rights" entail? Edit: There were a lot of really interesting and helpful explanation, arguments, etc. This has been interesting and enlightening, thank you! Everyone's explaining adverse possession but, honestly, outside of small chunks at the edge of adjacent properties and, let's be honest, you're not going to call your neighbor a "squatter" because a fence got built a foot on the wrong side of a property line. What most people mean when they talk about "squatters rights" negatively is the difficulty in kicking out squatters (trespassers) from abandonned property you own. We're not talking about them being there for years and having a legal claim to ownership, just them there a month or two & resisting eviction. Ultimately, this is an extension of . Now, if you're renting a place & the owner wants you out, they need to go to court and you by proving you've somehow violated our lease & need to GTFO. Because there's a large disparity in power between the involved parties, legally, the tenant gets to stay until the issue is resolved. People who break into abandoned properties, can use this principle to their advantage. If the cops show up to kick them out for trespassing, all they need to do is provide a minimal amount of evidence that they be legal tenants, and they can stay on the property until a full legal eviction proceeding has taken place. We're not talking about people who've spent on an abandoned property and own it, we're talking people who have been there weeks/months using legal loopholes to avoid getting trespassed. It's not really a legally defined right, just a side-effect of protecting legal tenants.
Why is gold valuable? Also, why was gold important to ancient civilizations? I know it has good conduction properties and doesn't deteriorate, but there are other similar elements. Why was it important for ancient civilizations, especially ones that didn't use currency? It's shiny, doesn't oxidize, yellow is rather unique as metallic color. It's also relatively soft and malleable with a low melting point (for a metal) that makes it a pretty nice material to work with and create art/religious symbols and being not that common makes it special, too.
If there are thousands of characters in the chinese and japanese language, how do they type on a computer? I can explain Japanese, which should cover both. They use a QWERTY keyboard, but there are different software keyboards that intercept what you type. So, they type for instance, nerihamigaki. As they type ne the software replaces it with ね. Replaces ri with り, and on and on. It would do this with each one until it has written ねりはみがきfor them. In Japanese, it starts with this hiragana and then a large list of kanji comes up, with the word you are most likely trying to write as the most recommended conversion:練り歯磨き. This word used both kanji and hiragana, but it could do it with only hiragana words, only kanji words, etc. Oh, and the word used here means toothpaste. :)
How are political parties so evenly split in the US? Because the parties want to win, therefore, they work to make it that way. If an idea becomes unpopular a party will drop it. If an idea becomes extremely popular a party will adopt it or at least make it less of an issue. Let's take gay marriage. Since 2001 to present more and more people are accepting gay marriage . In 2008, Obama was sort of against gay marriage. He said it was a state issue. His party was softly for it though. The reason was the issue was still unpopular. This meant the Democrats could have a bigger tent and include people that were against gay marriage, allowing them to have slightly over half of the vote that year. Now the tables have turned. Gay marriage is a popular issue and the Democrats (including Obama) embrace it as a party platform. And Trump and Republicans? Well, they don't make it an issue. They aren't gay marriage but not for it, allowing them to have people that are for it and against it and were able to get about half of the vote in 2016. So in essence, it's about half and half because the parties are both trying to win, and to win they both need ~51% of the vote. They will change their stances if their stances become unpopular.
Statute of limitations - why? Was just reading a news arrival about a Japanese murderer who has been on run for 45 years and their statute of limitations for murder (15 years) had been abolished in 2010.... My question is why is the statute of limitations a thing in some countries? If someone is caught and evidence proves it was them they should be able to get convicted 1 year or 70 years later? The statute of limitations is in place because as people age, memories become less accurate and more prone to influence. Being able to find witnesses for an alibi Also becomes less realistic. Imagine having tok explain where you were on 5/4/1987. Also, physical evidence deteriorates and being able to refute evidence using forensic tests becomes less realistic or accurate. There are a few other factors, but the main point of a statute of limitations is to ensure that a defendant has a realistic opportunity to defend themselves effectively against the charges being filed.
What is a fascist? Fascism doesn't have a universal definition that can fit every iteration. Due to its roots in extreme nationalism, the "flavor" of a fascist ideology will vary heavily based on its country of origin. Hitler's National Socialism was not the same as Mussolini's Fascism, or Franco's Falange. Any homegrown American fascism will not be the same as Nazism. But by and large, fascist ideologies tend to be extremely nationalist, extremely statist, and extremely racist. However, the fascist ideologies tend to share a number of common or similar factors. Umberto Eco's 1995 essay "Ur-Fascism" is extremely useful in this regard . Eco (who lived his childhood during Mussolini's rule of Italy) pinpointed 14 common factors that fascist ideologies largely share. I will attempt to briefly summarize each. . Fascists will attempt to combine their associate their new ideology with much older traditions and traditional imagery. For example, in , there are many shots of centuries-old churches, cathedrals, and other medieval architecture, frequently with huge Nazi flags flying over them; the objective being to associate Nazism and Nazi rule with the stability and longevity of these buildings. This also played into Nazi architecture (an imitation of classical Greek and Rome) and symbolism (Nazis heavily, heavily cribbed Roman imagery) . Fascists will reject modern culture, political values, and art. They will frequently attempt to portray modern, post-Enlightenment values and art as "degenerate" in some way. For example, the Nazis suppressed "degenerate" art by Modernist artists, decrying it as "Cultural Bolshevism" (an attempt by the Jews to undermine German culture from within) and either throwing said dissidents into concentration camps or expelling them from the country. They also encouraged their own vision of "traditional" art. . Thinking and intellectualism is weak, degenerate, and unmanly. Fascists persecute intellectuals because intellectuals will be their fiercest and most dangerous political opponents. Thus, they must be discredited, so their professions and habits themselves must be portrayed as "un-manly", "degenerate", or "cultural betrayal". Proper INSERTCULTURE men shouldn't stop to think like a Jew or a woman, they should throw themselves against the Enemy in defense of the Nation without hesitation. . Fascist dogma is irrational and largely a pack of lies, and will not survive dedicated analytical criticism. Building upon #3, intellectuals must be persecuted and dissent suppressed. . Fascists stoke ethnic, religious, national, and/or racial divisions to channel the energy of their populations. They must fear the intervention and machinations of a great enemy or enemies. Arbitrary lines will be drawn to divide "True Nationians" from "Others". For the Nazis, this was the International Jewish Conspiracy against Germany. . Fascism's biggest support tends to come from a frustrated middle class that feels they are under intense pressure. This middle class will be resentful of the wealthy and privileged upper class far above them and fearful of the restless lower class below. Fascist takeovers are typically precipitated by major economic stress and the spectre of a socialist or communist revolution. and . Fascists will seek to unite their key demographics through extreme ethno-nationalism. They will define what a "Tue Nationian" is via arbitrary lines and set that demographic against the Other. The Nazis used the Aryan ideal and anti-Jewish persecution to determine what a "True German" was. Additionally, fascists must convince their "True Nationians" that they are constantly under threat, under siege, by their enemies. They will do this by drumming up major xenophobic sentiments and targeting minority races and ethnicities. . Fascists must convince their people that their enemies are simultaneously so overwhelmingly strong that they humiliate the nation, but they also weak enough to be overcome by the united effort of the nation and people. Because they must encourage this narrative and in fascism dogma dominates policy, fascist nations frequently cannot objectively estimate the true strength of their enemies and will lose wars as a result. . Fascists are frequently extreme Social Darwinists. Struggle always improves oneself. The great enemy can only be overcome through struggle. The strong must constantly compete to determine the strongest. In reality, this creates a mess of petty, unstable politics as fascist officials backstab each other for advancement. Hitler's Nazi Party and German armed forces were an absolute mess of cross-jurisdictional conflicts. . Fascism is extremely hierarchical, and the masses from whom the fascists have seized power and mandate by force (it must always be by force in a democracy) must be kept under heel. Those who fail in the permanent struggle of life are weak and not worthy of attention. Fascists must despise their subordinates as weaker specimens of mankind. It is a popular elitism that plays into the fascist narratives of Social Darwinism and Ethno-Nationalist Identity. . There is no greater virtue than to die in service of the Nation. Men are encouraged to seek a heroic death on the battlefield above all things. The ideal fascist hero his heroic death and will not hesitate to throw himself (or his subordinates) into combat against the enemies. This is a critical step in indoctrinating millions of young men into unquestioning military service. . Women are held in contempt and confined to strict gender roles. Their primary purpose is to tend to the home and breed more soldiers. Hyper-masculine virtues are encouraged, and any lifestyle that runs counter (such as homosexuality) to hyper-masculinity is decried as "degenerate". . The People is a monolithic entity. The People must be willing to sacrifice their individual rights and freedoms and fall in rank to support the State and the Leader. The Leader represents the voice and common will of the People. Fascists will drum up populist imagery and rhetoric in order to seize power, but the population is expected to fall in line behind them once they are in power. For example (and combining with #10), near the end of the war, when the Soviets battled for Berlin, Hitler expressed ultimate contempt for his own people and claimed that the German people "deserved" to be annihilated by the Soviets - they had voted him into power (they didn't), supported him as the embodiment of their Common Will (out of fear), struggled against their enemies, failed, and thus deserved to pay the price of extermination. . Fascists must alter language itself to suppress criticism, dissidence, and "degenerate" art. They will frequently use loaded phrases to communicate meaning or encourage certain concepts. Frequently, any communicative media that is not run by the State is suppressed, because the only truth comes from the State, the Party, and the Leader. To go on a slight tangent here at the end, the popular film is a really great portrayal of the rise of a fictional fascist ideology, and it hits many of these exact points. And yes, Project Mayhem is , not anarchist.
Why do we twitch in our sleep? Basically your brain has a reflex to check if all the parts of your body is still alive. During your sleep, it happens that your brain, as it notices your catatonic state, feels the need to check if some parts of your body are still alive. It does so by sending impulses to the muscles through the nerves in order to obtain a response. The impulse to the muscle is the twitch you have. So don't worry: it's just your brain doing his job at making sure you're fine
Why aren't taxes just done automatically? Planet Money on NPR had an episode about this a little while ago. A big reason is that tax preparing (H&R Block, TurboTax, etc) is a huge industry that employs a lot of people, and they've been able to leverage that into political power to keep taxes complicated.
How are all planets spherical? Gravity. If you have a large amount of stuff in the absence of any other strong gravity, then it will tend to collect into the shape with the lowest total gravitational potential energy (you can think of it as the shape where every bit is as far "down" as it can be), which is a sphere. Having enough mass to pull itself into a near-spherical shape is actually part of the definition of a planet!
Why does someone gets hypoxic when on an unpressurized aircraft above 10,000ft, but doesn't when on the ground at the same altitude? Planes can ascend much faster than a human walking or driving so your body doesn't have as much time to acclimate to the lowered oxygen.
ELI5:How do shows like the Daily Show pull clips that may be several years old to make very specific points? With the second coming of John Stewart on Colbert this week, I was reminded how specific some of the clips they find are. Is there like a data base for every news anchor somewhere? I have no idea. This has been asked before and iirc, the answer was that there are companies with the sole purpose of recording TV and categorizing it on servers that shows like the daily show can pay to search through.
Why is The universe "flat" This doesn't literally mean the universe is flat like a piece of paper; it's not a literal description of the universe in the way we understand the word "flat". A spherical universe would be like the Earth: if you go in any direction for long enough, you would eventually end up back where you began. In a spherical universe if you flew in any direction you would eventually end up back in Earth. Evidence suggests that this is not the case. Look at a map, not Google Earth, but a real map. If you put your hand on Ghana and keep walking east, you're going to walk right off the map and onto the table, and you're going to keep walking until something stops you. A flat universe means that the universe doesn't have a curve to it that would result in you ended up back where you began, which would certainly happen if you completed a circumference of the Earth. Whether or not this means the universe is truly infinite is still a matter of debate, but the consensus is that the entire universe is infinite but the observable universe is very much finite; after all, the speed of light is the fastest you can travel in space, but the "speed of space", i.e. the rate at which the universe expands is much faster, therefore the unobservable invisible part of the universe that cannot be observed because it is older than light and is further away than light can reach us from, is considered effectively infinite as we have no means of establishing its size. Think about that using this method: imagine you cannot see, and your knowledge of reality only extends to how far you can hear. You are confined to your home, so the furthest you can hear is the road outside. This is the absolute limit to your knowledge, but does it mean that there is nothing beyond? A universe that is truly flat, i.e. truly infinite in every definition of the word, would have infinite energy, thus infinite mass. Think of it like a procedurally generated video game: no matter how far you go, there is no limit to what you can discover. A spherical universe would have finite energy and thus finite mass, so there is a fixed and undeniable absolute maximum to how much the universe can support. A natural process of the universe is entropy, which is the natural decay of the universe caused by energy being lost. In an flat universe, entropy could be reversed because there is infinite energy, so electrons and protons breaking down would be like sand being washed from the beaches and ending up somewhere else: the energy survives. In a spherical universe, this would not be the case: energy that is lost is lost forever, and there is an inevitable and inviolable fate where the universe will die.
How and why is Flash Player apparently such a security risk to users? Everything I google and read keeps bringing up that it is full of security risks and holes, but nothing explains why. How does using this thing put my computer or information at risk? Secure languages provide separation of code (the bit that does things) and data (the bits which have things done). They provide things like bounds checking (is the data being written bigger than the space you are writing to? is the address you are writing to part of the variable you think it is, or is it part of something else?) and strict type checking (is it the same fundamental type of thing?). Flash doesn't have these things. And, it appears to depend on being 'mutable' -being able to construct new code, and then point to it and say "run this" which is a hugely flexible thing to do, but very hard to do securely. Flash is written to be 'helpful' so its written to provide services which look like 'display this picture' but the same logic can be doing things in the background, the user isn't always able to know. So, it can do things you don't know are happening. Flash is significantly less constrained than other things, in what it can do to your computer. It runs inside some tools which are not 'sandboxed' -that is are not confined to a kind of virtualized substate, where they cannot write outside of areas which are tightly controlled. Flash can access your network. So it can set up to download extra code, including cracking code, which exploits other weaknesses in your host, and then allows it to be abused by other non-flash systems. If you combine all of this, you have something which is very compelling for some people to use, because its so flexible, but that flexibility is the root cause of its massive insecurity. It should be removed, and people should move to using more secure frameworks to support 'actionscript' tasks like the sandboxed javascript environments built into the browser. There is very little flash does which couldn't be done by something else.
Despite every other form of technology has improved rapidly, why has the sound quality of a telephone remained poor, even when someone calls on a radio station? This gets asked often and you have a slight misconception. Telephone quality has remained the same, because what's called Plain Old Telephone Service (or POTS) pretty much the same because it's ubiquitous and it works. But the technology that's used for what telephones are used for improved - we have technologies that far eclipse POTS and available. ISDN, for example, has been available for decades - ISDN calls are so crystal-clear that many phone companies to the line because people were assuming the line was dead! But if you wanted ISDN, you had to pay a more, whereas POTS was already running to your apartment and mandated to be cheap! Nowadays you can also get phone services through your cable company, or use a cellphone, etc. Many people are switching away from POTS.
Why does inbreeding cause birth defects? Imagine your traits in terms of DnD stats. For simplicity let's give you five traits (in reality you have a ton): STR, CON, DEX, INT, WIS. For each stat, you got one number from your mom, and one from your dad. The better of the two becomes your stat. So for example, your stat table may look like this: You take the best of what you got from your parents, so you end up with final values of 15 STR, 9 CON, 9 DEX, 17 INT, and 9 WIS. Note that your dad gave you an absolutely atrocious DEX stat: 0.5! But that's OK, because it gets covered up by the 9 from your mom. Until you have kids, that is. When you have a kid, then for each stat, one of your two numbers gets selected. You pass that number to your kid. So for INT, you could pass down your dad's 17, or your mom's 12. It's 50/50. Without inbreeding, everything keeps going normally. But, what happens if you have a kid with your sister? Well, now's where that terrible 0.5 DEX from your dad could come into play. Your sister might have that 0.5 DEX gene also. You have a 50/50 shot of passing down that 0.5. With any other woman, it would just get covered by whatever DEX stat she passed down. But with your sister, she also has a 50/50 shot of passing down your dad's 0.5 DEX. And in the 25% chance that you and your sister both pass it down, then there's nothing to cover it up. Your kid will have 0.5 DEX and be a cripple.
Why are there so many different programming languages, and what's the difference? This is because everybody is free to develop a programming language. Besides that everybody has his own taste and requirements. There are languages which are for example more suited for web or standard applications, others may be more low-level to build more specialized stuff. Languages can evolve or fork into different tastes, or die out over time. Popular languages will often have big and active communities who contribute to it's development and deliver standard building blocks which can be reused by other developers.
What is a 401k? A 401k is a special savings account with three rules: 1) You pay much less tax on what goes into a 401k (and, if you want, don't have to pay any tax at all on it until you take the money out) 2) You can only put up to $18,000/year into the account 3) You can't take the money out until you turn 59.5 years old (you actually can, but you pay a penalty that totally removes the value in putting the money there in the first place) The program was created by the US federal government to incentive people to save for retirement. Typically you pay a percentage of each paycheck into your 401k, and most employers will match what you put in up to a certain percentage (usually 2-6% of your paycheck). Employers do this as a benefit; whatever percent they match can effectively be seen as a raise, which is pretty nice.
Sleep paralysis. I'm not a scientist or doctor but I've had this since I was about 12, hundreds of times. When you go to sleep your brain stops communicating with your body to move/react so you do not react out on your dreams and potentially hurt yourself or those around you. Some sort of peripheral nervous system disconnection?? What happens is your mind wakes up without telling your body to. This can be terrifying and also include hallucinations. It has also been referred to as the old hag; an idea that some witch or demon is sitting on you and sucking your life away. When this happens I still sometimes get scared but most of the time I recognize what is happening and calmly pull myself out of it. If this happens to you and you're scared, focus on moving something such as a finger and once you're able to it will immediately stop in most cases.
Why are most homeless people guys ? One contributing factor may be that women, especially women with children, tend to get some priority when it comes to shelters and housing programs.
the concept of bankruptcy I read the wiki page, but I still don't get it. So it's about paying back debt or not being able to do so? What are the different "chapters"? What exactly happens when you file bankruptcy? Isn't every homeless person bankrupt? From the previous thread - this is a great ELI5 version Like you're Five: On the day you get your allowance, you buy a bag of candy. The next day, you want more candy, but you spent your allowance, so you ask your brother if you can borrow his allowance, and pay him back with your next allowance. You buy another bag of candy. The next day you ask your sister if you can borrow her allowance, and promise to pay her back when you get your allowance. You buy another bag of candy. When you finally get your allowance, you realise you're in trouble - you can't pay your brother and your sister. You get so worried about it that you go buy a bag of candy instead. When you get home, you get in a big fight with your brother and sister about it. When your Mom asks what you're fighting about, your brother and sister tell her that you borrowed money and you won't give it back. She asks you why not, and you say that you spent all of the money on candy, and you don't have any money left. She sighs, and makes you give all the candy you have left to your brother and sister. They want to know when they get their money back, and she tells them the money is gone, and they need to stop fighting with you and forgive you. They say that that isn't fair, and she says that it really isn't, and that they should remember this the next time you ask them for money.
ELI5:Why do grocery stores use huge rows of open refrigerators without doors, while some refrigeration units at the very same grocery store will have doors which would presumably be much more energy efficient? It turns the whole side of the store into an igloo; making customers cold and uncomfortable would seem to not be a good idea. Or does the laziness of not having to open a door to get to your food product win out over the coldness and huge energy costs? No one has a door-less refrigerator at their house The energy costs on an open cold case are not as high as you might imagine. It's very different from simply leaving the door open on your refrigerator. Open cold cases are equipped with air curtains, which are sets of narrow vents that blow cold air from the top of the case into corresponding vents at the bottom of the cases (which draw that air in). This effectively forms a "curtain" that helps prevent the cold air inside the case from mixing with the warmer air outside. Cases that are heavily shopped and require frequent re-stocking (many times per day), such as produce and meat cases, are less likely to have doors because this reduces the time needed for employees to work the product, which saves money on labor, and it also makes it easier for customers shop, which invites more sales. These items are also much less perishable and able to withstand greater temperature fluctuations than frozen products like ice cream, which you will never find without doors. Side note: the retailer I work for once experimented with doors on all of our wall coolers, including meat and produce, for a little more than a year, not to save money directly, but to collect some kind of energy-efficiency tax credits. Those same doors came off just as soon as those tax credits expired (or so I was told).
Why does NASA assume that there is no life on planets that has conditions that are not ideal for humans, when the organisms on the planets could have adapted to their respective conditions and thrive? Let's say you are walking down the street and dropped your keys. They might have landed in the gutter, or gone down the sewer. Where do you look? You look in the gutter because if they are down sewer, you won't be able to find them. That's the approach organizations searching for life are taking. We know a about earth like life, and have very good ideas what it might look like from light years away. We know nothing about other forms of life, and might not be able to detect it in our own solar system.
What is the purpose of the International Space Station? And the space program in general for that matter. Like most people reading this right now, I'm a science oriented thinker driven by curiosity and turned on by knowledge. I hear political arguments on the opposing view that (US tax) money is better spent elsewhere. What are the main goals and expectations of the space program as it stands now, funded by 'the people'? The space station is currently used for conducting experiments in micro gravity. But it can also be used as a checkpoint for longer missions that require heavy payloads. For example: if we want to send a ship to the moon we can send the ship without fuel to the ISS (International Space Station) and then send the fuel tank to refuel the spaceship. Tell me if you require further explanation
Why is our brain programmed to like sugar, salt and fat if it's bad for our health? As humans, we're only separated by about ~20,000 years from our hunter/gatherer ancestors. That period of time is extremely short in terms of evolution so although we live completely different lifestyles, our bodies have not changed much. We crave sugar, fat, and salt because they were "healthy" back in those days just because of how rare those things were to our hunter/gatherer ancestors. Being able to eat the calorie dense sugar and fats means that we would be able to survive more days without food, improving our overall "health." We needed salt to replenish all the salts lost through sweat because humans are built for endurance running (early human hunters would jog along until the prey runs out of energy). The humans who didn't crave sugars, fats, and salt would not build up enough energy and wouldn't survive as well as those who did crave them. Nowadays, the food industry takes advantage of our primitive brain cravings to sell us more food. Normally, a person only eats a constant amount of food. If that was the case, for the food industry, the profits will never increase. They have to make people eat more food to generate profits. Thus, there is a strong incentive to put more sugars, fats, and salt in our foods so we eat more of it, regardless if it was healthy for us.
Why do most Redditors add the "Edit:" tag to their comments even if all they are doing is fixing spelling mistakes? https://www.reddit.com/wiki/reddiquette
Why is W called "double U" when it is clearly "double V"? When Old English was written, it used a mixture of Latin letters and older runes. One of these runes was Wynn, which was used to represent the wound that w gives today: https://en.wikipedia.org/wiki/Wynn That runes was sometimes replaced by the combination uu - a double u - for the same sound. In german, the letter v changed in sound to be pronounced as f in most cases (it still is). In a few cases the v-sound was retained. To distinguish these cases, scribes began to write vv for these. When printing was developed in what is today Germany (and to some extent Italy, but that is less relevant here), the printing press manufacturers made types for the letters that they had. Since the combination vv was very common, they made a letter for it - w. In most languages letter is called "double-v". These printing presses and the letters for them were exported everywhere, including to England. The English quickly realized that they didn't have types for all their letters, so they made do with what they had. Since English didn't have the w before printing, they simply reused that letter for the Wynn rune, which was missing. It is called "double-u" because it was also sometimes written as "uu" Similar story for the letter Thorn, which was also missing when printing and became the "th" combination. https://en.wikipedia.org/wiki/Thorn_(letter)
Why is it impossible to travel faster than the speed of light? The issue is relativistic mass, time dilation and other stuff. To put it simple, an object going fast is heavier than an object going slow. So, if we have a rocket engine with constant thrust, the arceleration will appear to slow down as it approaches the speed of light, because the mass of the object increases and increases. At speed light, mass would be infinite, which would require infinite force. Instead, the rocket continiously approaches the speed of light, but the closer it gets the slower it approaches, never reaching it's goal.
Why do we get that uncomfortable feeling when seeing a deep wound/blood? Agreed, it's probably an evolution thing. I always think this regarding people fleeing / ignoring an injured or sick person on the street etc. Of course you get some that go to help, but the majority of people will literally run away. I can only think that it's a subconscious evolutionary programing. As dumb as it sounds when you actually think about it, seeing someone harmed makes us scared for our own safety, even if what happened can't effect us. Instinctively our brains will engage the flight or fight response. Most will flee for self preservation. We see it in animals all the time.
If black is the color that absorbs the most energy, why green is used by nature? I guess it's because it may burn them, but why green? Is there something special with green? Can't we use that special thing? Thanks ! Because photosynthesis isn't just about absorbing energy, it's about it, and for that black pigment would actually do more harm than good. The various proteins and enzymes involved in photosynthesis are very fragile, and can only handle so much energy at once. Black pigment would result in too much absorbtion, and would basically cause the leaves to overheat, which actually efficiency. Plus, most green plants aren't in places where sunlight is scarce; the restrictions on their population are more due to animals eating them and a lack of water/nutrients, not sunlight, so greater energy absorption simply isn't needed. Plenty of plants (especially in the ocean) black, or red, or blue, or some other color more suited to their particular situation. You can read more in this helpful /r/askscience FAQ: https://www.reddit.com/r/askscience/wiki/biology/black_leaves
Why do we have to wait at least 10 seconds in the middle of restarting the router? Routers and most electronic equipment have capacitors inside. They are like electricity accumulators, like micro batteries. One of their functions is to assure that electric signs are not lost in the circuitry. So they pump extra energy to assure that. When we turn the router off we want that that all the information disappears ( so we can start again), and there is the risk that the capacitor is keeping that information still alive. Since the capacitor is connected to the circuitry (there is no flip like batteries: they are constantly working) it will keep discharging to all the components, wasting all its energy and making sure that its not keeping info alive. Also ten seconds is a myth. In theory they shouldn't last even a second. the 10 seconds rule came from the PC's hard-drives that had to with for the disk to stop
Why do spinning car wheels sometimes look they're spinning backwards? Pretend your eyes can only see at 1 frame per second (fps). Now replace the wheel with a clock, with both hands on the 12 position. Once the clock-hands (wheels) rotate faster than our eyes can process, they appear to move backwards.
Why people don't have any memories from the first 2 or so years of their life? the brain doesn't actually develop the capacity to store long term memories till several years after birth. The brain goes through a lot of stages in life, becoming more complex and more structured, till around 22 years old.
How do radio stations know how many listeners they have? Do they have ways of measuring like TV channels do? Here in Germany, they have devices for TV ratings, but radio listener numbers are estimated via telephone interviews, in which people are asked which stations they regularly listen to. Since the dates for these are well-known (similar to sweep months in US TV), private radio stations will often try and push their brand awareness during those times by running all kinds of stunts and media campaigns in order to get people to remember their names. (A common gimmick, e.g., is randomly calling numbers in the area, and if the people answer the phone by directly saying the station's name, they'll win a prize.)
Why does Tilt-Shift make things like that? The short answer is that your brain is just used to seeing that kind of focus on small things. Lots of "tilt shifted" photography is just a normal picture where they simply pull the top and bottom parts of the image our of focus. Normally this kind of focus occurs when you take a picture or video of a very small object and therefore can only get a small depth of field in focus. Since our brains are so used to seeing small things like this, it just assumes that the image is of something very small. Funnily enough, this is the reason for lots of different optical illusions. Human vision is really really "heuristic" based, meaning it takes lots of shortcuts and uses lots of tricks to generate our perception of things. This is just one example.
Why do we procrastinate? Procrastination does not even make sense (or?) but still we do it. Why? What happens in our brain? Why do even have the ability to procrastinate? I saw a great video on this subject. A professor who has been studying procrastination for a long time lectures on what procrastination is and isn't, why people do it, and how to fight it. As for my best explanation.. We humans are a very short-sighted species. When I, a college student, have some free time and am deciding what to do, I have two options. I can work on my assignment, or I can goof off. Working on my assignment is obviously more productive, but I've had a long week, and I deserve a break, and a few minutes of goofing off won't hurt anything. I have plenty of time to finish that assignment, so I'll wait until later to do it. So here I am on Reddit. Fast forward to next week, and my assignment is due the next day. I haven't even started it. I've had numerous opportunities to work on my assignment, and have passed it up every single time. Why do I do it? My brain isn't trying to sabotage me or make my life worse. It just sees so much more pleasure in goofing off than in trying to do my homework, so it impulsively chooses to goof off. It doesn't make sense for us to do it because it's so bad for us. So is fast food, drugs, alcohol, and many other vices many people partake in. We're not procrastinating or doing those things because they're good for us. We're doing it because we enjoy the short-term pleasure of doing it.
How do conductors control an orchestra? And could an orchestra play without an conductor? Let's separate out the two main roles of the conductor. The first is to be the music director, preparing the orchestra during rehearsals for the performance, making stylistic calls and generally interpreting the music. For example, the conductor picks the tempo, and the conductor may have some vision for which instruments should be louder or softer at some particular point in the piece, or how they should perform that passage, or something like that. The second role is to actually stand on the podium and wave a stick to conduct the orchestra. I think that's the one you're asking about, right? The big thing that the conductor does while conducting is keep time. The conductor is essentially a big clock. Not all ensembles need a big clock in front of them. A rock group, for example, depends on the drummer to do that job. But orchestral music often isn't that easy, and the conductor can speed up or slow down at will, so the conductor keeps everyone together. The other big thing the conductor does is convey emotion and dynamics (volume). How does he want this passage played? Well, look at him and you should be able to see it clearly in the way he waves the baton, in his face, etc. Big, sharp motions? Loud and strident. Tiny, quick motions? Soft and light. Wavy motions with a face of constipation? Emotive and smooth. Yes, the conductor have just told everyone this stuff during rehearsal, and he probably , but it's just too much to remember, and besides, the musicians are busy with their own parts. Another important thing the conductor does is cue people. The conductor knows when people are supposed to come in, and while the players ought to know that stuff too, the conductor motions to them directly to make sure that things happen as they should. It's easy to doubt yourself and wonder if this is the right time, and looking at the conductor's cue, you can be sure that it is. What would happen if the conductor were not there? Everyone would look to the leader of the ensemble. In an orchestra, that's the concertmaster, the first-chair violin player. That person would set the tempos with relatively slight gestures, and everyone would just do their best to remember the expression and keep their own time until the concertmaster needs to do another cue or lead a slowdown or something like that. Plenty of groups don't play with a conductor, and one isn't really needed if the players can get away without an external person cuing them. They can cue each other. But the larger the ensemble, the more salient the need to coordination, and that's the job of the conductor.
Why in so many parts of the world are salt and pepper the ultimate and preferred condiment and seasoning? If you are curious about salt get the book Salt by Mark Kurlansky and prepare to have your mind blown. Salt was not as abundant as it is today and it used to be much more valuable. Cities were built on the salt trade, people were paid in salt (ie the phrase "he is worth his salt", also the word salary is derived from the Latin sal meaning salt), you could not go to war without salt. Salt is why Chinese brine extractors were drilling bore holes thousands of feet down 500 years before the first oil well in America was drilled at just 60ft. People in England proudly lay waste to the landscape, pulling brine from underground untill sink holes started appearing, boiling it untill the skies were black from soot, in pursuit of the purest, whitest, finest salt. Every fisherman was also a salt farmer. Months on end farming salt in the heat of the tropics, then sailing to far away seas near lands unknown where fish were so plentiful they could be scooped out by bucket. Today things are the opposite. White salt is almost freely available where impure salt (eg. pink himalayan salt) is highly prized. Salt isn't needed for fishing anymore but fish are scarce. Its really an interesting book and you won't look at the salt shaker in the same way again! Dono about pepper. Edit: to actually answer the question: Firstly, salt intensifies the flavour of your food, so it makes sense to keep it where you eat. Secondly, as mentioned salt used to be very valuable so keeping salt on the table was also a display of wealth. It was sometimes kept in ornate dishes and handled with special customs. Some cultures do not have salt at the table or even use it directly in cooking. Much of Asia uses salty sauces such as Soy sauce or fish sauce. Dono about pepper. Edit 2: since this has ballooned - salt was so valuable for two reasons: If you didn't have a cold storage place or it wasn't winter, meats and vegetables had to be salted to stop them going rotten. Therefore a large portion of food had to be salted, especially for campaigning armies or navy ships where even fresh food was hard to access. Nowadays we have much less demand for salt due to refrigeration and canning/packaging technology/freeze dry etc. Satisfying the huge demand for salt with limited production capacity means it had high value. Supply and demand people! Please stop asking about pepper.
ELI5:Why do we get the feeling that we want to jump down when we stand next to a cliff? A philosophy professor once told me this was an example of existential anxiety. You're not scared you'll fall; you're scared you know you can jump. We are free to do whatever we want, our existential freedom, and this is something we often run away from or avoid. It's also a sense of existential anxiety in that it simply reminds us we will die one day, another life fact that we often try to avoid thinking about. Another example he gave me on this subject was how sometimes when you're driving, you realize that all it'll take to cause a giant car wreck that might kill you and other people is just a little slight turn to the other lane - and into the oncoming car.
Why do humans have different blood types, and is there a purpose to the variations? Human blood types most likely came to exist to fend off infectious diseases. The incompatibility of some blood types, however, is just an accident of evolution. There are four main blood types. Blood type A is the most ancient, and it existed before the human species evolved from its hominid ancestors. Type B is thought to have originated some 3.5 million years ago, from a genetic mutation that modified one of the sugars that sit on the surface of red blood cells. Starting about 2.5 million years ago, mutations occurred that rendered that sugar gene inactive, creating type O, which has neither the A or B version of the sugar. And then there is AB, which is covered with both A and B sugars.

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