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ablkcw | how does mass hysteria work and how can it manifest physical symptoms? | /title | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/ablkcw/eli5how_does_mass_hysteria_work_and_how_can_it/ | {
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"It's pretty much a huge case of fomo with the placebo effect. You see a bunch of people doing something and your mind thinks that the might be something triggering it that effects you so you begin to physically manifest something like an uncontrollable urge to dance or some kind of sickness"
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3fiu2i | why does hard cheese which has been maturing for years have a sell-by date of only a few weeks? | Thanks! | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/3fiu2i/eli5_why_does_hard_cheese_which_has_been_maturing/ | {
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"It's been cut.\n\nAs long as the outside of the cheese is entirely the outside of the cheese (the rind), the cheese will have a substantial shelf life. As soon as you cut it, opening up the more moist interior to oxidation, mold, and bacteria, it has a shelf life. That being said, some cheese (like parmigiano reggiano) will, in my experience, simply get rock hard when kept for too long, rather than spoiling in some way that makes them inedible.",
"I worked in the cheese department at a grocery store where cheese wedges are cut from big wheels and there are a lot of fancy, expensive cheeses. When we would cut pieces off the wheel we would put a price tag with a certain \"expiration date\" on them but when the cheeses were getting close to that date we would just re-wrap them and put new price labels on them...We would also cut off mold spots and re-wrap them to sell. ",
"The majority of these comments are accurate but there's one thing I've seen to be mentioned.\nCheese is a very tricky food, it requires much care and handling.\nCheese isn't just packaged then thrown in some guys basement to age, it is kept inside of temperature/humidity controlled areas to reduce/increase moisture and so on. Also a reason why you will see cave aged cheese sometimes. Different kinds of conditions make for a different kind of cheese, it's just about knowing what you want from your cheese!",
"The most common cause of cheese \"going bad\" in my experience is mold. Mold growth is easy to prevent in a controlled cheese aging facility. In your kitchen it's damn near guaranteed. ",
"Cheese is more than a dairy product that you add to your eggs or pizza. It's essentially a living creature. A fungus really. It's a carefully controlled rot of milk, salt, and rennet. When it's mixed right, kept in the right environment it will grow and age into wonderful fully grown cheese. It's similar to beef. Why does beef have a short shelf life. It's been just put in a field or a barn or what have you for years. It's because once you kill the cow cut off the bits you want, the meat will start to spoil. Once you crack a wheel of cheese it died. Unless you are good about keeping the exposed bits sealed. But once the cheese is cut up and packaged. It's a dead part of a once living organism and will succumb to the mold and bacteria that live inside it that make it, well cheese.",
"The sell by date is to comply with government and/or corporate standards. It's not a \"becomes poison\" date.\n\nMost cheeses can still be eaten long past their sell-by date as long as they don't visibly look bad (mold, dried out, weeping), or smell off (ammonia smells, especially, are not a good sign). If the cheese still presents as a perfectly good cheese, you can eat it. If there's mold on the cheese, you can usually scrape it off and eat the rest. \n\nAs for why cheeses tend to go bad when technically they're already \"rotten\", that's because part of the cheese making process is to figure out what the optimal age for a cheese is. I mean, you still want to make a product that tastes good. The cheese companies know what age makes a good cheddar, gouda, parmigiano, etc. and produce and sell cheese according to that timeframe. ",
"How do they pack all that cheese flavor into a bite sized cracker?",
"Mostly because you dont have the condition to keep cheese in the same environment that it was aged in. Plus in most countries it is law to have expiration date on all products even if it last forever(Honey/salt/sugar). ",
"French here, most French cheese does not have an expiration date or I haven't heard of a French trowing old cheese. As I get it here, the oldest it gets, the stinkier it becomes. And stinkier = better. "
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5k1mjr | why is video ram (like gddr5) so much faster than regular ram (like ddr3 or ddr4)? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/5k1mjr/eli5_why_is_video_ram_like_gddr5_so_much_faster/ | {
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"I know that the VRAM (video RAM) is only faster because it can be without losing stability. \n\nThere are also less compatibility issues, because it serves only one purpose, and doesn't have to juggle tasks. \n\nI hope someone else can expand on this, but that's what I know for sure. ",
"GDDR, similar to GPUs are very parallel in design.\n\nSo while you might have \"dual channel\" or \"triple channel\" memory slots on a system board, GDDR memory can be arranged into 8, 16, or 32 parallel channels on the graphics circuit board. This yields nearly linear performance gains in memory throughput since memory chips are accessed in parallel. For this to work efficiently, this requires that the graphics chip itself is also designed to be massively parallel (unlike CPUs) with hundreds (or thousands) of cores / shader processing units that are all loaded up between ticks and all fired simultaneously on the clock tick.\n\n\n",
"VRAM is dual ported DRAM, it can read/write at the same time. This is necessary since VRAM is used as a frame buffer, so you can ouput the final image in the frame buffer without blocking the GPU.\n\nThe rest of the speed increases generally come from configuration of the Graphics Card and how a GPU works. VRAM is technically not faster but just has a wider bus.\n\nCPU's do sequentual work. Today we use 64bit architectures which will read/write in chunks of 64bits into memory.\n\nA GPU, does vector math, so instead of having a single register to operate on one 64bit value, they'll operate on an array of 64bit values. A GPU will need to pull out a lot of values out of memory to do an operation so the VRAM has a wider bus to pull out an array of values much faster. So instead of reading a 64 bit value, a 512b bus can read 8 64bit values at once.\n\nGenerally reading multiple values has a higher latency, so for a CPU to use VRAM it would actually be slower because it would increase the latency for a CPU and would still only be able to read/write in chunks of 64bit. For a GPU the additional latency is offset by being able to read/write more values at once.\n\nedit: I modified my answer based on telling someone else why a CPU would not get benefit from VRAM. I feel like it explains how the differences of a CPU/GPU differ and why the GPU just needs a different type of ram. It may also be oversimplified on the GPU end... "
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3gg2um | in david attenborough documentaries, how do they get the camera inside each respective insect/animals home? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/3gg2um/eli5_in_david_attenborough_documentaries_how_do/ | {
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"If you have the DVD/Blu-Ray sets, watch the behind-the-scenes extras. \n\nThese nature photographers spend months and months working to catch the perfect moment (really makes the viewer marvel and appreciate their contributions to public knowledge)."
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7rbul5 | how come the military is "always recruiting" and are all countries like this? | [deleted] | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/7rbul5/eli5_how_come_the_military_is_always_recruiting/ | {
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"People are always leaving and moving up even when an army downsizes. Ergo there are always needs for replacements at the bottom. \n\nNow you may not get to be a helicopter pilot. There is always need in the infantry",
"There is a high turnaround in the military. A lot people join the military for a temporary job once they graduate high school. They only serve for a couple of years because: they need money for college, they figure it's a cheap way to learn a trade (mechanic, technician, driver, etc.) their parents kicked them out and they a need place to go, they have dreams of being war heroes but are quickly disenchanted, etc. Once they meet their short term goals, they leave the military and continue on with their lives. In this case, they always need new recruits to fill in the gaps.\n\nIn some, it depends on the current government policies. If you have military happy government, recruiters will lower the standards and accept more people. If the government cuts military funding, fewer people are accepted.",
"People leave the military a lot.\n\nEnd of contract, injuries, KIA, suicides, etc...\n\nSo they always have openings.",
"1) Drafts are no longer in effect in most countries so they only have volunteers, which means they have to recruit. \n\n2) There are always people leaving the military (retirement, medical discharge, behavioral discharge, death) and those people have to be replaced. That means that they have to recruit all the time. ",
"Most people join the military for a few years, so they need to keep replenishing the ranks since people keep leaving the military. They can use various financial incentives, training program access, how much advertising, etc. to control their immediate needs. Also often has to do with how the general job market is how hard they have to recruit."
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85vkyj | how do people doing gymnastics always land on their feet? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/85vkyj/eli5_how_do_people_doing_gymnastics_always_land/ | {
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"They spend years failing to land on their feet. Its an enormous amount of practice, and even then they aren't always perfect."
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1xeh0s | i'm an adult. why do i always dream about school? | I've been out of college for eight years. In my four years of time there, I dropped out of exactly one course because I was too disinterested to attend class. Ultimately it had no negative effect on my graduation.
And yet, since that year, I've had the same dream at least twice a week: I'm back in college, I've completely neglected to attend several courses for some reason, and now it's the end of the year and I'm freaking out.
What is my brain doing, here? Why do I have "stress dreams" about a situation that, relatively, wasn't all that stressful? Why don't I dream about going broke, or getting sick, things that actually cause me to stress out in my waking life? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1xeh0s/eli5_im_an_adult_why_do_i_always_dream_about/ | {
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"Because your school years were the most formative years of your life.",
"You can think of it as a very, very mild form of Post Traumatic Stress Disorder (PTSD).\n\nBasically, you dream of it because you went through it. If someone does go broke and lives on the streets or get very sick enough that it impacts their life, they will probably have nightmares about being back in that situation."
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5met1x | how can someone who lost all movement from below the neck breath without aid? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/5met1x/eli5_how_can_someone_who_lost_all_movement_from/ | {
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"In some cases they absolutely cannot, and must use a machine such as an \"iron lung\" or respirator.\n\nIn other cases, although their voluntary nerves aren't working, the other nerves that run automatic systems are still in good shape."
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22w62d | why do adolescent girls seem to be more obsessed with boy pop stars (think justin bieber, boy bands, the beatles, etc.) than adolescent boys are obsessed with female pop stars? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/22w62d/eli5_why_do_adolescent_girls_seem_to_be_more/ | {
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"Pop stars maybe. Trust me, as an adolescent, I was obsessed with anything with breasts. I had Heather Locklear and Bo Derek posters all over my room. Pop is a lot more mainstream and the musicians (if you can call them that) get a lot more publicity today than in past times, thus they are more visible and people obsess via social media - which we never used to have.",
"Boy pop stars are marketed to girls.\n\nGirl pop stars are marketed to girls.",
"I am a man and I would bang the fuck out of Justin Bieber. Just saying.",
"That phenomenon goes way back. Franz Liszt had panties thrown at him already, and the knights in tournaments received their tokens of favor too.\n\nI guess it comes down to hypergamy: women are attracted to social status. And a performer in front of a crowd, in combination with media campaigns are pretty effective way to simulate social status. And once enough girls start buying it, it becomes real social status.\n\nMen are attracted to fertility. That can be faked too, hence the cosmetics and fashion industry, and more than enough men fall for it as well. But the thing teenage boys look for they can find in all the girls around them in their daily lives. And often those girls are as unattainable to them as pop stars are to the girls.",
"Because there are a whole bunch of other male icons for boys to obsess with. Sports superstars, male leads in movies, tv shows, animes, comic books, in addition to a number of male stars in music.\n\nBias also probably plays a role here, young boys would rather be dead than to be caught liking stuff that girls like and mercilessly made fun of by their other male friends.",
"Girls want boys that other girls want. Guys just want girls, any of them, it doesn't matter",
"I agree with some of the other answers, as a once-adolescent girl with a once-adolescent brother, he had porn to watch, which gave him all the 'female' he needed in his life. I on the other hand, was of course told in various ways that porn is gross and for boys and girls never looked at that, and my friends were all PISSED if they found their boyfriend looked at any kind of porn etc. I was also warned extensively that any older male might possibly molest me and/or be a rapist or pedophile, so I should stay away from them and be disgusted by their sexuality. \n\nSo what good looking, in my age range, guys did I have? Boy bands. ",
"Jo Koy explained this best. He was talking about how girls try to get backstage because they want status. But guys at a Madonna concert, when asked to go back stage would be like \"Why? There's a perfectly cute girl selling popcorn right there.\"\n\nIt's essentially biology. Guys want to pass on as much seed as possible, girls want their children to be taken care of, and more importantly obtain the \"best seed\" possible for their children. The \"best seed\" would come from those who have high status in the society.",
"I believe its called the sexy grandma hypothesis. Or something like that. If you have kids with bieber... Chances are your kids will inherit his traits. That means lots of people swooning over your kids. That means lots of grandkids. \n\nSo for a gal, theres a huge incentive to go for the popular guy (from an evolutionary standpoint). ",
"Because girls are allowed to like 'boy things' and 'girl things' but boys are only allowed to like 'boy things' because 'girl things' would be a step down because femininity is seen as weak and inferior."
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59mytl | why arent any saudi royals on the top billionaire lists? are they not filthy rich from oil? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/59mytl/eli5_why_arent_any_saudi_royals_on_the_top/ | {
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"Those guys are also not particularly transparent. Since Saudi Arabia is an absolute monarchy, the country's budget and state investment funds are also the royal family's own wallet, whereas \"conventional\" billionaires own far more easily detectable corporate assets.",
"There are thousands of Saudi royals. Saudi Arabia is similar to Germany just after its formation where you have a lot of kingdoms and principalities. You even have outlying kingdoms that is not part of the empire. The \"emperor\" of Saudi Arabia does not have full control over all the kingdoms. There are different tax systems and different laws depending on where you are. Some have full Sharia and some are quite progressive. So the income from oil is distributed to all the royals in Saudi Arabia and there is no one super rich individual. In addition the top wealth lists are very open to speculation. When you are rich you might want to hide your real fortune or it might be locked up in less tangible assets that is hard to value. A Saudi prince might get a $2B loan from the bank based on his connections and future oil income but does that mean he have $2B even though that is all debt?",
"Many of the billionaire lists specifically exclude heads of state from being eligible for inclusion on their list. If heads of state are included, it can become very hard to assign what is the head of state's personal property, is it the whole nation, some proportion of the nation, how do they treat the Queen of England (who made an agreement with the nation of England to trade their personal holdings for their expenses being paid). ",
"It's difficult to determine what's owned by a Saudi royal himself, and what's owned by the state because is royal family is the state. Royalty can pull directly from the state's coffers. "
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3rp0op | why does it matter that young people don't vote? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/3rp0op/eli5why_does_it_matter_that_young_people_dont_vote/ | {
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"Broadly speaking, young people not voting shows there is a lack of engagement. This can mean they don't feel like anything will change, or can change. \n \nThis matters because for democracy to function properly (i.e. have checks and balances, a knowledgable electorate etc.) people actually have to give a damn. And what many young people don't realize is, they can make a difference.\n\nMost places, 18 year olds can vote. These are people in university/college, or starting in the work force. Governments play a major role in their lives (i.e. setting tuition levels and stuff like that), so if they have a vested interest in the outcome of the elections.",
"Whether it matters or not depends on what party you are in favour of. Young people overwhelmingly identify as democrat. So if you are in favour of democrat policies / a democrat president, the fact that young people feel that way but don't vote should matter greatly to you.\n\nIf you are republican, young people voting isn't necessarily an advantage to you, but you might still be very much in favour of everybody getting involved in the democratic process that elects the government. ",
"It turns old people into the ruling class, so laws and policies are created in favor of their interests and views. "
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5jh8s8 | why does eating human flesh lead to "the shakes"? | For the record - I'm not planning on any crazy dietary changes. I just watched The Book of Eli and it's mentioned repeatedly, I'm curious as to what the correlation is. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/5jh8s8/eli5_why_does_eating_human_flesh_lead_to_the/ | {
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"They probably adapted the real disease [kuru](_URL_0_). It's a prion disease, similar to Mad Cow disease. A prion is a protein that is folded up wrong. Besides not doing its normal job right, the prion makes other proteins become misfolded. The accumulation of these prions causes brain damage. In particular, kuru results in movement problems such as shaking and an inability to walk. \n\nKuru is spread by cannibalism, particularly of the brain. It was found in a Papua New Guinea tribe thay practiced cannibalism as part of funerary rites. It's pretty rare now that the practice has stopped, but it has an incubation period of up to 40 years so there could still crop up occasionally among people who used to practice funerary cannibalism. ",
"Kuru is a real life disease caused by a prion transmitted through consumption of infectious brain matter.\n\nIt was first noted in Papua New Guinea in the 1950s and 60s and has largely remained only in that area due to endocannibalistic practices. They eat their dead.\n\nEating the flesh of a person who wasn't infected with the disease isn't harmful. At least no more harmful than eating most other meats."
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5eqqbv | what actually are the trigometric fuctions? | I pretty much know the basics of trig; how to find sides, angles, unit circle, graphs, etc. So here's my question: I know a tangent is a line that touches a circle at one point. But then what actually is a 'sine' or a 'cosine'?
It would also help telling me why the trigonometic process is done. (Not getting the answer but why is it done THAT way) | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/5eqqbv/eli5_what_actually_are_the_trigometric_fuctions/ | {
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"EE student bored at a huge family Thanksgiving meal, I'll give this a shot.\n\nThe sine function takes an angle, traditionally labeled 'theta', as its input, and spits out the corresponding ratio between the opposite and hypotenuse sides of a triangle. Specifically, using [this image](_URL_2_) as a reference, you can say that sin(theta) = opp/hyp. \n\nIf you were to plot the sine function as theta varies from 0 to 360 degrees (as theta is just an angle), you would get the classic \"sine wave\" - this is simply a plot of how the ratio between the sides of a triangle varies as you change theta.\n\n[This gif](_URL_4_) should help with the intuition a little bit, here's what's going on: if you watch as the circle (with radius 1) is traced out, really what you are seeing is a triangle with the ratio between sides varying as a function of the angle, the definition of the sine function. [Here](_URL_3_) is what you would see if you took a snapshot of the previous gif. As you let theta increase in the picture, if you reach 90 degrees (pointing straight up) you'll have hyp = 1 and opp = 1, so sin(90) = opp/hyp = 1, as expected. Similar reasoning will show that sine(180) = 0 (since opp = 0), and you can continue to move around the circle to find whatever sine value you are interested in. Understand - **asking for the sine of any number is just like asking \"what is the ratio between the opposite and hypotenuse of a triangle with this angle?\"**\n\nFollowing so far? Here's where it gets interesting.\n\nSine, described above, gives you the ratios between the opposite side and the hypotenuse. If hyp = 1, then sin(theta) = opp/hyp = opp. In other words, it is just the vertical component of the diagonal vector. [Visually](_URL_0_), if we say that the hypotenuse of the triangle represents force (labeled F), taking the sine of the angle will give you the vertical component of the force vector (labeled Fy in the image). Now, since sine is defined as sine(theta) = opp/hyp, we can say: hyp*sine(theta) = opp. In other words, given a vector we can find the vertical component using sine.\n\nBut what if we wanted to find the horizontal component of the vector? Well, cosine is defined as cosine(theta) = adj/hyp. It shouldn't be hard to convince yourself, using a similar argument, that the cosine simply spits out the horizontal component of a vector.\n\nEDIT: I messed this up, slight correction in the comments below. ~~Logically it follows that if you take the sine and cosine of the same angle and add them you will always get 1 - sine and cosine can be thought of as the \"percentage\" that the vertical and horizontal components respectively contribute to the vector of interest, 1 being 100%, which is why sin(90), a vertical line, is 1, while the cosine of the same angle is 0. This is why sin(45) = cos(45) = 1/2, both the vertical and horizontal components contribute equally to the vector pointing at a 45 degree angle.~~\n\nAs an aside, [if you plot the cosine and sine of an angle on the same graph](_URL_1_), you'll notice that the sine and cosine functions are related - specifically, cosine is just sine shifted over by 90 degrees, i.e. sin(theta + 90) = cos(theta). Interestingly, if you noted the \"slope\" at every point of the sine function and plotted it you would get the cosine function. This means, by definition, that the derivative of sine is cosine - I'll leave it at that to keep this in the context of ELI5, learn calculus for more detail.\n\nFinally, we can get into an amazing theorem devised by my main man Fourier - essentially, using the fact that sin (and by extension, cos) are the most fundamental way of mathematically expressing periodic (repetitive) motion, Fourier proved that any periodic motion, no matter how complicated, can be expressed as the sum of simple sin and cosine functions (a Fourier series). This is the heart of modern signals processing used in engineering and technology.\n\n\n\n",
"[This GIF](_URL_0_) depicts it exactly.\n\nWhen moving around a circle, the sine function represents your vertical movement and the cosine function represents your horizontal movement.",
"Here's one of the best ways of describing the point of trigonometric functions that I've ever seen:\n\n > **Motivation: Trig Is Anatomy**\n\n > Imagine Bob The Alien visits Earth to study our species.\n\n > Without new words, humans are hard to describe: “There’s a sphere at the top, which gets scratched occasionally” or “Two elongated cylinders appear to provide locomotion”.\n\n > After creating specific terms for anatomy, Bob might jot down typical body proportions:\n\n > * The armspan (fingertip to fingertip) is approximately the height\n* A head is 5 eye-widths wide\n* Adults are 8 head-heights tall\n\n > How is this helpful?\n\n > Well, when Bob finds a jacket, he can pick it up, stretch out the arms, and estimate the owner’s height. And head size. And eye width. One fact is linked to a variety of conclusions.\n\n > Even better, human biology explains human thinking. Tables have legs, organizations have heads, crime bosses have muscle. Our biology offers ready-made analogies that appear in man-made creations.\n\n > Now the plot twist: you are Bob the alien, studying creatures in math-land!\n\n > Generic words like “triangle” aren’t overly useful. But labeling sine, cosine, and hypotenuse helps us notice deeper connections. And scholars might study haversine, exsecant and gamsin, like biologists who find a link between your fibia and clavicle.\n\n > And because triangles show up in circles…\n\n > …and circles appear in cycles, our triangle terminology helps describe repeating patterns!\n\n > Trig is the anatomy book for “math-made” objects. If we can find a metaphorical triangle, we’ll get an armada of conclusions for free.\n\n[...snip...]\n\n > **Tip: Trig Values Are Percentages**\n\n > Nobody ever told me in my years of schooling: sine and cosine are percentages. They vary from +100% to 0 to -100%, or max positive to nothing to max negative.\n\n > Let’s say I paid $14 in tax. You have no idea if that’s expensive. But if I say I paid 95% in tax, you know I’m getting ripped off.\n\n > An absolute height isn’t helpful, but if your sine value is .95, I know you’re almost at the top of your dome. Pretty soon you’ll hit the max, then start coming down again.\n\nYou can read the whole post to better wrap your head around trigonometry here: _URL_0_"
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fed03x | why does the body consume carbohydrates first and then fats when exercising? | [deleted] | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/fed03x/eli5_why_does_the_body_consume_carbohydrates/ | {
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"The actual answer is a bit more complicated than that. What cells actually use for fuel is ATP, which is an energetic protein that we make using carbohydrates, fats, and other things as a fuel source.\n\nATP is mostly produced by mitochondria, organelles inside cells, and muscle cells have a lot of mitochondria.\n\nAt any given time, we have a little bit of liberated sugar, glucose mostly, which is floating around in the blood, being taken up by cells that need to produce more ATP, and being used by them to make ATP. When we start to exercise or burn a lot of calories, the amount of free glucose we have in the blood goes down, so we start liberating it by making more out of molecules we have stored.\n\nThe big ways we store energy are as glycogen, a long-chain sugar in the liver, and fat. It is pretty easy to separate glucose from glycogen, so that is the first form of reserve energy we go to. It is a more time-consuming process to make glucose from fats, and there are more bad by products produced. So we don't start burning fats until our bodies know we are in it for the long haul.",
"Fat is designed for long term storage in case food becomes scarce. It holds significantly more energy than carbs. A little over twice the amount per gram, actually. So your body wants to only expend what it needs to, as carbs are a weaker energy source, they are the first to go, while it tries to hold on to fat for as long as possible in case of food insecurity.\n\nRemember your body evolved in a comparatively unstable environment with predators still hunting us. Food was a lot more scarce so it is good to have long term energy storage (fat) in case of drought, famine, or any other reason why a food source would dry up. So it created these systems to keep you alive long enough to make babies. Burn the carbs first- keep the fat until you have no food.",
"The short answer I learned is, carbs are an easier and faster source of energy\nFat takes more effort to get energy from.\n\nAnd the body doesn't really plan ahead in the same way you do, your body has no idea if you are going to be running for 5 seconds, or 40 minutes. Your body just knows \"oh your running, better fill up on energy\"\n\nIt'll go with the easy solution first."
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alby6r | why can't a country in a trade surplus be sustained in that position indefinitely? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/alby6r/eli5_why_cant_a_country_in_a_trade_surplus_be/ | {
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"It can.\n\nImagine you have a job at a convenience store where they give you a 50% discount on baseball cards. You don’t care for them much, but your friend does. He regularly buys them from you for 90% of list. You never buy anything from him.\n\nYour friend has a trade deficit with you. The trade, though, is beneficial for both of you and you’ll keep doing it as long as it works out for both of you. And you’re not living outside your means to do it. \n\nYour teacher may have been talking about a budget deficit, which is a whole different thing. That is living outside your means. \n\n*edit: I had the trade deficit backwards. Macro at 7am never safe. "
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61dbl4 | - why is citizen kane considered to be the pinnacle of movie making? | What is it about Citizen Kane that makes it such a highly regarded movie?
A lot of the time when someone is talking about if a movie is good or not they'll say something along the lines of "It's no Citizen Kane or anything". It almost seemed to be used as a benchmark of moviemaking.
So why is this movie so highly respected? What makes it such a good movie? Is it the acting, cinematography, sound design, etc? What factors make it the pinnacle of movie making?
Also do you believe it deserves all the praise? Is the name it's built for itself deserved? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/61dbl4/eli5_why_is_citizen_kane_considered_to_be_the/ | {
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"It's really more popular with people in the movie industry. It doesn't normally top the list of general audiences.\nIt's partly revered because it's kind of a film making clinic. So many techniques used in the various aspects of cinema are used, and used very very well.",
"It's less about being the pinnacle of movie-making and more about being the _start_ of modern movie-making. \n\nIn _Citizen Kane_, director Orson Welles revolutionized how films were shot. There are a number of cinematic techniques that were introduced in _Citizen Kane_ including low angle shots, multiple dissolves, deep focus, non-linear storytelling (in particular supported by the film editing), people talking over one another (most films were shot then as back-and-forth dialogue), full sets with four walls and a ceiling (most films then were shot on sets like stage plays -- 3 walls, no ceiling), incorporation of fake documentary/news reels (which Welles had pioneered on radio with _War of the Worlds_), expressionistic lighting, and more. \n\nAll of these things are so commonplace today that you'll see them in many 30-second commercials, never mind feature films. But in 1941 they were all almost entirely new innovations that people had never seen until _Citizen Kane_. \n\nWatching _Citizen Kane_ today, you'd think \"What's the big deal?\" But the *reason* you think \"What's the big deal\" is because of all the techniques that _Citizen Kane_ introduced to cinema. \n\nPossible recent analogy: think about how the special effects of something like _Jurassic Park_ or _The Matrix_ in the 90's or maybe _Avatar_ in 2009 changed the way that people thought about how films could be made. _Citizen Kane_ had _ten times_ the impact that those films had in people's thinking about how films could be made. ",
"If you look at the silents or early talkies, they are almost like theatrical plays. Static stage, camera, and lighting. The story is usually pretty linear, and told exclusively through dialogue (and maybe a bit of action)\n\nIn Citizen Kane, most of the locations are filmed through several different cameras, some at some fairly unusual angles. And a great deal of care is taken with the lighting. All this gives a much greater sense of the locations being actual places instead of a stage with the curtains hidden from view. It also was pretty innovative with the narrative frame - there are flashbacks, montages, and so on. Citizen Kane wasn't necessarily the first movie to use any one of these techniques, but it did so many of them, and executed them so well that it has come to be seen as kind of a master class in how to use the unique properties of cinema to create artwork that wouldn't be possible in any other medium. And the acting, dialogue, cinematography and all that is very well done.\n\nIt also probably acquired a certain amount of mystique because Orson Welles was such a young and unknown quantity in Hollywood when he made it, and then never really lived up to that early promise. It was also very controversial when it came out, because the incredibly powerful newspaper magnate William Randolph Hearst (whom Kane was based on) tried to bury it during production. ",
"Besides its innovations, the performances are amazing, and the guts the unknown Welles demonstrated to take on William Randolph Hearst at the time is testimony to the power of art itself.\n\nThe storytelling is so strong in certain scenes, also. Check out the dialogue-free scene in which Kane and his first wife grow older through a montage of eating breakfast over the years. She is shown reading his newspaper every day until the end when she picks up the rival paper, showing the rift that has grown between them. \n\nAnd the always phenomenal Joseph Cotton is the quintessential \"best supporting actor\".\n\nWatch the movie RKO 281 with Liev schreiber to learn more about what it took to make this film and why it's so important.",
"There are a lot of reasons for Citizen Kane being highly regarded outside of its historical significance. As /u/DoctorOddfellow explained:\n\n > In Citizen Kane, director Orson Welles revolutionized how films were shot. There are a number of cinematic techniques that were introduced in Citizen Kane including low angle shots, multiple dissolves, deep focus, non-linear storytelling (in particular supported by the film editing), people talking over one another (most films were shot then as back-and-forth dialogue), full sets with four walls and a ceiling (most films then were shot on sets like stage plays -- 3 walls, no ceiling), incorporation of fake documentary/news reels (which Welles had pioneered on radio with War of the Worlds), expressionistic lighting, and more.\n\nBut it's important to note that it's not just that Welles used these techniques, but *how* he used him. And in fact, many of the innovative things he did where already done in previous films (deep focus is used heavily in The Rules of the Game, 1939), but he was the first to do them all in a single movie. The final chapter of one film textbook I read was dedicated to explaining why Citizen Kane is so great, and it opened by stating something along the lines of, \"Every shot in the movie contains meaning, and the worst of the shots are merely very good.\"\n\nSo to give you an idea, [here's a famous shot that students typically look at in film school.](_URL_0_)\n\nHere are some things to look at:\n\n* Single shot once we enter the house/cabin. Creating continuity in time, and also means that the blocking in this shot is all related\n* Contrast between how the mother is dressed (formal) vs the father (casual)\n* The camera moves away from the window with the mother in the foreground and father in the background, suggesting further that she has control over the scene\n* They sit down. The characters are arranged so that the father is the only one standing. Usually a character standing suggests strength, but since he is still in the background and his dressed casually, this blocking convention is somewhat subverted, just as this scene subverts gender dynamics as a whole. Also, as they debate over the fate of a young Charles Foster Kane, he is scene in the background, between the two parents, playing in the snow. (This all being visible to the audience is an example of his use of deep focus).\n* As the drama in the scene escalates, the father moves to the foreground and the camera tilts up (still the same shot). The shot goes from a wide to a medium-wide, low-angle. The continuity in movement further articulates the rise in drama, and suggests a last ditch effort by the father. He now appears more menacing than before. Maybe there is more to his relationship with his wife and son? \"Anybody doesn't think I've been a good husband, or father...\"(we find out a few moments later that he is not a good father) Note: Charlie is still in the center, background. \n* As the mother signs, the camera tilts back down, excluding the father from the frame, indicating that he has no agency in this scene, or this moment. The mother owns the scene, the mother has \"won\" the scene\n* After the papers are signed, the camera rises, and the father moves back to the window and shuts it. The closing of the window following the signing of the papers, suggests that these documents have actually ended the boy's blissful childhood, a major theme of the movie.\n* They are all standing now and move towards the window, and the mother actually opens in one last time. The dialogue in the following closeup, with her action of opening the window reveals that she may not be as cold as we were previously lead to believe, that she does care about her son's well-being, and this is what she thinks is right for him.\n\nAnd that's just one shot in the movie. That's not even going into the overall structure of it and the depth of the narrative. There's a lot going on in Citizen Kane, and it's acclaim is not unwarranted. Roger Ebert did a commentary track for it, which is supposed to be fantastic. That can explain in more detail why it's a near perfect movie. \n\nEdit: Words",
"This doesn't answer your question, but it's one thing that adds to its mystique. Orson Welles co-wrote, produced and directed *Citizen Kane* when he was only 25 years old.",
"Well, for one it was highly innovative. Pioneering most, if not all, modern filmaking techniques. Even down to things like story structure, abstract concepts, location filming and more.\n\nSecond, it is a really really good movie. Like brilliantly so. Tells a huge story in concept, but it's also cerebral, sensational, funny and deals with real human flaws. That is also super modern.\n\nA lot of stories in film beforehand were like, fantasies. ",
"Apart from technical reasons another factor that plays into its fame was its opposition by William Randolph Hearst - the media mogul that feel that Kane was too much of an autobiography about him that didn’t put him in the most favorable light. He was notorious in exhibiting a lot of pressure to not getting it made. RKO (I believe) defied him and released it anyway."
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80nw7e | what is the difference between federal debt and u.s. treasury securities? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/80nw7e/eli5_what_is_the_difference_between_federal_debt/ | {
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"The debt is issued through the use of US Treasury securities. The government sells a bond, and the money collected from the bond buyer increases the debt until the bond is paid back."
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2n6l6c | why does semen lose its white color after 5 min? | What makes it white and why is it not white anymore after 5 min? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2n6l6c/eli5_why_does_semen_lose_its_white_color_after_5/ | {
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"Ok, so: semen contains very little actual spermatozoa and a lot of other components, one of which are alkaloids produced by prostate to - basically - neutralize the acidity in a vagina, so that the spermatozoa survive long enough to reach the egg.\n\nThe alkaline stuff oxidises when it contacts the oxygen in air, which makes it change colour.\n\n^(source: high school biology, I guess?)",
"\nIt shoots out runny so it'll come out easily, but it has stuff in it that turns the semen hard almost straight away so it'll stick in the vagina. The stuff that turns it hard it changes the shape of proteins in your semen which makes the colour change (think about cooking an egg white). When the effect of that stuff wears off it turns runny again so the sperm be able to move up towards the egg. \n\n",
"It shouldn't if you squirt a little lemon juice on it.",
"I just wanna start out by saying....okay, 23 comments but only 9 are readable? Thats pretty horrible.\n\nThe color of the semen is caused by the types of cells and molecules that are all mixed together when travelling from the testes, through the Vas Deferens, and coming together with the alkaloids from the prostate (as /u/thehollowjester has said). \n\nOne thing that causes the Viscosity and color of your semen to change, actually is largely affected by your sperm count. The thicker and whiter your semen is, the higher your sperm count. You would notice that, if you ejactulated multiple times in a row, your semen will get clearer and clearer. That is because your ejaculating faster than your testes can produce. Ever seen precum before you actually ejactulate? Its got a super almost nondiscernable amount of sperm, which gives it its clear color and very watery texture.\n\nSo in conclusion, what is causing your semen to turn white, not only is the oxidation of the molecules, but also your sperm dying off within your own semen and degrading. Which in turn, actually turns them clear.\n\nSource: Phlebotomist/Nursing student",
"I have to ask. What situation are you in where you ejaculate and you haven't cleaned it up after five minutes?\n"
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15a2d7 | sinuses | Why does my throat seem to swell up and go numb after a sneezing spell? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/15a2d7/eli5_sinuses/ | {
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"More importantly... why can't my girlfriend taste anything anymore?? Some kind of sinus infection that's lasted weeks ;_;",
"Sinuses are hollow cavities in the skull to lighten the bone structure. They are lined with mucous tissue, and can be subjected to allergens, causing the mucous to swell and produce mucus. This can plug up the sinus cavities and cause pressure and pain. Why your throat swells up and goes numb really has nothing to do with your sinuses. It probably has more to do with histamine release that caused the sneeze in the first place. Here is a good pic of sinuses. _URL_0_ \n\nAs far as not tasting, it's probably because her sense of smell is diminished from sinusitis. \n\nShe needs to see a doctor. I suffer from sinusitis, and it's horrible. There have been cases where the sinusitis has been caused by nasal polyps, which can be removed fairly easily if they are small. Most sinus problems are allergic or viral/bacterial. "
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4txahf | if you start off completely awake and energized but then start dozing off during a boring class or a study session, what exactly is happening physiologically to cause this ? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/4txahf/eli5_if_you_start_off_completely_awake_and/ | {
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"Your brain notices that there's nothing of interest going on at the moment, and tries to shut down to conserve energy. Your studying might be important to you in a higher-function way, but at a core animal level, it's not food, sex, stimulation, or entertainment, and so you're just wasting energy and calories (and therefore dangerously wandering towards starvation and death) by being alert and awake. ",
"In this case, your brain can be compared to a car with a bad idle. When you're interested and engaged, your brain has it's pedal on the accelerator and it runs fine. When you are doing things that are not as interesting to you the brain loses engagement and starts to idle. It has trouble maintaining the idle and starts to shut down against your will. Generally, the idle state can be maintained in normal people, but some have issues with it.\n\nThis is actually a sign of mild narcolepsy and you should get tested at a sleep center. I had the same symptoms and that was my diagnosis.",
"I had a buddy who had this issue. So he comes over one day and he's like, \"Man I just don't know what's up, I can't stay awake in class. It's like an 8 am'er but I get a good night's sleep before hand and I grab a giant 32oz coke on my way so I'm loaded with caffeine. The next thing I know I'm waking up and the class is leaving. I don't know why I can't stay awake, it's not even that boring\" So this goes on for several weeks, and finally he decides it's bad enough to hit up the campus clinic.\n\nTurns out the dude is a minor diabetic. He was basically sending himself into a diabetic coma every morning in his attempt to stay awake! Made a few life changes like cutting out soda, getting some exercise, and switching to Miller Lite and walla, drops 35 pounds, and gains a ton of energy. \n\nI don't necessarily think this is your issue, but your story reminded me of it.\n\n",
"I was taking night classes a few years ago. I was working, married, kids, mortgage, yadda, yadda. I could not stay away during my Calculus class. I found out that if I took a 15 min nap in my car before class -- that I would wake up automatically. And, I would be completely refreshed for my class. I have since learned that it is called a \"power nap\" and I use it all the time.\n\nBut, it is KEY ... to wake up after 15 mins.",
"Basically, your brain is like:\n\n\"okay, I'm safe, I'm well-fed, and there's nothing too interesting going on...might as well sleep to save energy\"\n\nThat's basically it. Happens to me too; I get really tired if I'm bored and have nothing to do.",
"If this happens in the morning it could be you just feeling sleepy because your body dips in energy. A little caffeine could fix it. If it'sat night you might just need sleep. Otherwise if it's boring do caffeine. If you're worried about sugar you can do coffee. Tea works if you just need a small amount and don'tlike coffee or espresso.",
"This is going to get buried, but... It might be your eye sight. If your eyes have a hard time focusing on near objects, it may cause your brain to go into overdrive trying to make sense of what the eyes are reporting. Causes one to become tired after maybe 5 - 10 minutes of reading. ",
"Fun fact: if you find yourself singing or humming on a regulaor basic, that means that the job is too easy and its not taking any effort. So if your mind is needing to preoccupy yourself, you'll find yourself humming/ singing (Depending on the person obviously). ",
"Ozzy and drix aren't too happy with your decision making. They think there's better things to be done.",
"I was dozing off at the drop of a hat ... no amount of red bull, pro-plus or double/triple espressos could keep me awake ... turned out I had a B12 deficiency.\n\nNow whilst I don't doze at the drop of a hat I do have issues with exhaustion and have not had a restful nights sleep of more than two-three hours for over ten years. I've been diagnosed with CFS/ME now!",
"i have the same issue but i wake up more tired than i went to sleep. it doesnt matter when i go to bed ill sleep 11+ hours if i set no alarm. \n\ncould sleep right now at 9pm and id wake up at 9am late for work",
"This is me. I fall asleep all the time. In lectures, in talks, in meetings. I once got myself tested for sleep apnea, they said that nothing was wrong. Not overweight or anything either. I've had this \"problem\" ever since I was in Grade 10 or so.\n\nIt doesn't really negatively affect me, except that other people see me sleeping, so in that way it does affect me negatively. The interesting thing is that people don't understand that it's unconscious - it's not like I choose to go to sleep. I am awake, and then the next moment I'm not. The discipline I'm trying now is that as soon as I find myself nodding off, I have to struggle to regain consciousness and force myself to get up or something instead of doing the constant head-bobbing thing that people who are falling asleep do."
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btlpao | if supermarkets have a defined science/art as to where products are located, why are they all different? | My experience from Tesco, Sainsburys, ASDA, Waitrose and M & S show that in every single store the format is always different. Either completely mirrored, flipped on itself, some products coupled with others in a different way, and freezer/fridge aisles sometimes together sometimes apart, sometimes by the entrance, sometimes in the middle. Why is that if there are now defined principles in what you should place where, and even if each company believed in different principles, why doesnt each company at least standardise their own stores? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/btlpao/eli5_if_supermarkets_have_a_defined_scienceart_as/ | {
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"Numerous factors- \n\n1 Store size. Different stores are different sizes, and shapes depending on the area they are situated and the availble space/ planned market.. What works for one floor plan doesn't neccesarily work for another.\n\n2 customers. Customers in different areas like different things, so different branches carry different products, and or different stock levels. This means certain types of product need more space in some stores then others.\n\n3 There's more then one possible arrangement that works well.\n\n4 They do tend to have LOTS of things in common. Walk into any supermarket. Fresh Fruit and Veg is almost always the first thing you come to. Dairy products are always kept together. Dental and medical supplies are in the same isle, sweets biscuits and crisps are next to one another. And so on.",
"In addition to other answes, the customer base is also factored in.\n\nFor example, when you walk into a Target, whose demographic is women, you see things women are drawn to (in general): women's clothing, jewelry, foundations, shoes, gift cards. \n\nMove to the opposite corner of the store for 'guy' things like electronics, sports gear, tools, fixit things you can't even see from the entrance.\n\nThen there is the hard-flooring racetrack around the store for getting at grab-and-go things like branded foods, detergents, personal care where no decisions are involved. You always buy Crest toothpaste and Tide detergent, so it's easy to find and grab just off the racetrack. If you get deep off the racetrack, you find things where you will need to stop and think and choose, like clothing, toys, small appliances and baby items. Clothing areas are carpeted because it reflects a higher end experience that customers prefer when shopping clothes. \n\nA different big store like Walmart has a different customer base (lower income, with younger kids) so you will see loss-leaders and seasonal stuff like school supplies by the entrance, but a similar racetrack for common items and carpeted clothing areas."
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3js7nv | why do people with loads of money still attempt to earn more money? if you have millions in the bank isn't that more than enough? | I was thinking about this all day. If I had £1 million in the bank, I could live off the interest for the rest of my life. I appreciate that just because you're loaded you don't immediately quit your job, but why do millionaires still have the desire to earn more. What's the real difference between a millionaire and a billionaire? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/3js7nv/eli5_why_do_people_with_loads_of_money_still/ | {
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"Generally I would say that people who are millionaires tend to have a high performance drive. They desire to always perform better. This is what made them wealthy in the first place, and this is what makes them desire ever more wealth. You can always do better.\n\nFurthermore, once you reach the level of being a millionaire, you'll move to a new level of wealth. You'll have all these people around you who are wealthier than you are and can do and buy things you can't. So compared to them, what used to be enough all of a sudden isn't enough anymore.\n\nThat is my take on it anyway.",
"To me it seems like addiction. You play a game and you enjoy it, then what's enough isn't a question and you only want more. Other reason is selfishness which is basicly root to all evil deeds in humanity.",
"You could live off the interest, potentially. \n\nBut that would be if you're willing to just live off of the monthly income. Emergencies happen. Some purchases require more money. Plus, if you're making enough to have a million in the bank, you're probably used to living a lifestyle a bit above the interest income. Is that income based on the stock market? Then its going to be up and down as that roller coaster goes. Keep in mind once you're no longer employed that you'll have to buy your own medical insurance (if you're in the US). Its not cheap compared to what you pay if you have one through an employer, since they pick up part of it, usually.\n\nMe personally, I'm going to continue working. But then again, I plan to retire from my main job (owning part of a small business) around age 45. What I have in the bank plus my secondary business (rental properties) is going to have to carry me the rest of my life. I'm not counting on social security.\n\nAnd I live semi-frugally. I could probably survive on the interest. Especially once I get the house I'm living in paid off.\n\nSource: I do have a million in the bank. It did, however, take me 11 years to get to that point, its not like I did it overnight. I'm going to work another 10 years or so before I semi-retire. And to accomplish that, I had to put 40% of my income after taxes into the bank/other investments. So, after taxes, figure I'm living off about 40% of my income as well. That, and running my small business consumes 60-80 hours a week of time as well as being on call all the time. Is it worth it? Sure. But I'm going to make sure I'm able to sustain myself the rest of my life too, comfortably."
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e2fvdf | how to barcode scanners instantly detect what an item is, despite the barcode being at any angle and often on a crinkled surface, completeley changing the look of the code from the scanner's perspective? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/e2fvdf/eli5_how_to_barcode_scanners_instantly_detect/ | {
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"The lasers that read the barcode hit it from many angles and scan it very quickly. Also barcodes have something like a checksum, where it's easy to recognize if the data that was read is garbage and needs to be read again. That's why when using hand scanners, like at the grocery store, sometimes it scans a valid item very quickly, and somtimes it takes a while. \n\nThe built-in scanners in the checkout lanes have lasers that shot from the sides and from the bottom.",
"The barcodes is designed in such a way that they are easy to read in different conditions. For example the very common UPC-A barcode used to encode almost all retail products all have the same number of bars and only differentiaties in the width of the bars in relation to each other. The barcode is not valid in reverse but can easily be detected as being in reverse allowing the scanner to reverse its scan direction if you scan something upside down.",
"It depends on the scanner for many of those to be true. A very simple barcode scanner will simply read one direction (allowing some but not much tilt) while others will use various techniques to account for these challenges.\n\nIn most cases, a beam of light is fired at a thin foil that is extremely sensitive to current change, allowing a rapid low current to be pulsed in to control the angle of the beam. Some, such as grocery store checkout lanes, supply multiple beams and reflectors allowing any angle to be scanned. \n\nThe reflection of the beam is sent back to the scanner when a reflection is possible, toggling an internal state between 1 and 0. During this, either the duty cycle - the time between “reads” of that 0/1 state, is constantly slowed and sped up, or the pulse rate to the reflectors is variated, changing the sampling rate very rapidly. This allows for distance to be much less of an issue. Basically, there’s always a beam of light and the hardware is asking repeatedly “Do you see the emitted IR light?”\n\nThat data is pushed into a cyclical buffer, and each read triggers a checksum calculation. Since the length of the code(s) are known, it allows the assertion “If these are the numbers, their sum should calculate to the check digit.” - if the checksum for example is just a basic digital root, and the numbers read as 6,4,8,3,7, then 6+4+8+3+7=28, 2+8=10, 1+0=1, so the check digit must be a 1.\n\nTo detect the start and end of a barcode, a specific character is often used - since were dealing with binary, it’s often a non-numeral character such as * or a,b,c - this extra data not only serves the purpose of telling a scanner where a start of a barcode is so it knows it can use more processing power to actually read the code, but the kind of code it is so it knows what checksum formula to use and how long to expect the barcode. These little details allow them to be extremely fast as it’s quick to tell, “If my buffer doesn’t start with *, it’s not a barcode, keep reading”\n\nYou can act see the effects of that on much older scanners, they’ll start flickering at a certain rate, quickly ramp up and down, then shut off when it hits that known character, often pausing for 1-2 seconds before the register receives a barcode.\n\ntl;dr, you can take a piece of paper and put a series of dots in a Braille fashion, 1 dot for one, 2 for off. Start a metronome and “read” whatever is under your finger, even if it’s the same dots or 3 dots apart, moving your finger at a constant rate, counting on/off, and grouping every 4 dots. Convert from binary to numbers. Repeat adjusting the metronome up or down until your finger hits each dot once per tick. That’s all it’s doing just using light.\n\n(I don’t expect you to actually do that but if you do - props - it also illustrates how much faster computers are at “thinking” than we are."
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3jzq5e | why do most websites have character limits for passwords while at the same time they force you to have an upper/lowercase letter, and a number to make your password more secure. wouldn't removing the character limit and allowing much longer passwords make them more secure than 16 characters? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/3jzq5e/eli5_why_do_most_websites_have_character_limits/ | {
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"Convention.\n\n\nThere is no technical strength to doing so. Users who will use insecure passwords without the restrictions will use insecure passwords with the restrictions, and cracking these cases isn't all that much more demanding. Meanwhile, increasing password length does substantially increase security. It would be far better practice to have, say, 10 characters minimum and no maximum than is currently common. ",
"Fuck forced password security.\n\nI have memorized 6 sets of 8-digit random strings of numbers and used them for passwords since I was a kid. I've never been hacked, had my password guessed or anything, etc. I have never written them down and have never forgotten them.\n\nNow I have websites telling me I need one upper case, one lower case, AND one \"special character.\" Now I forget my passwords all the fucking time or I HAVE to write them down. Fuck. \n\nForced password strength is dumb. Now I need to use shittier annoying passwords so whatever website can protect dumb people who use their pets' names as passwords from getting hacked.\n\nEDIT: And ESPECIALLY fuck websites that make you change it after a certain amount of time. If it hasn't been hacked why the fuck do I need to change it? Does someone have my password and they're like \"eh I won't bother for a couple weeks\" and you intend for me to foil them by simply changing it? Can't they get the new one the same way anyway??",
"I'd be ok with it if they would just say what those restrictions are when signing in - the same info it says when registering. Like:\n\nUsername:\n\nPassword (must have one capital and a number):\n\nSince every site is slightly different, I have a ton of variations of my usual passwords. This would help me remember which one I used on a particular site.",
"In the past there were multiple ways to store passwords and were acceptable for some time. The oldest way was encryption, then hashing, now salt and hashing. \n\nWith encryption, your password is converted to characters and symbols. The problem? Your encrypted password can be run through a similar conversion process in reverse, known as decryption.\n\nThe method after decryption was hashing. Hashing is one way, meaning that it goes through a conversion process like encryption, except there is no \"reverse\" process to unhash a password. The only way a \"hackor\" could get your hashed password using is guessing your password over and over until they find a hash that matches your hashed password. The problem? It's relatively easy to figure out hashes today. You can typed some hashes into Google and get the original text. \n\nToday we still use hashes, but now add a bit of salt. Salt is random text that gets added to your password before your password is hashed. This way if a hair hackor gets your password, they can't easily crack it. If there was a rogue employee they would also have a hard time getting your original password. \n\nWhen a hackor guesses passwords, the longer the password is and more variety of characters, the longer it takes to crack (at least for hashing). Salting passwords makes these extra password requirements less effective today, but still would be helpful if your password was ever compromised. \n\nThis video does a great job explaining: _URL_0_",
"Most people building websites nowadays have internalized that special characters and password length are necessary for strong passwords. The special characters is a lesson that's well learned (I know, \"correct battery horse staple\", but password generators/managers are IMHO even better). \n\nUnfortunately, many also seem to think that a standard password is somewhere around 8 characters, and therefore they believe that doubling this to 16 is a huge step. They are mistaken and a maximum of 16 characters is still quite short for several types of serious attacks. \n\nAs for why having character limits at all: character limits are included to make sure that user input does not exceed any arbitrary but technical limits of the user or server platform. For example, if a common browser would not be able to send more than 255 characters as the value of the password field, then it makes sense to have a certain limit that's below this known technical limit to avoid weird undefined behaviour. \n\nThe problem is when websites have a very low limit. It's unnecessary on a technical level: no current server or browser platform has technical limits this low. So 16 characters is really a stupidly implemented restriction and also a hint that the security people don't know how to do their job properly. Beter character limits should be much closer to e.g. 100 characters. Arbitrary, I know, but almost nobody will hit this limit and for now, it's good enough. And it has negligable impact on website performance. \n\nNOTE: it is also not a matter of reserving a column length in your storage layer! This is an appallingly bad reason for limiting password lengths and if a developer suggests this, this developer should not be let anywhere near any security feature (or be fired completely!) At no point should the platform attempt to store your password in plain text; instead it should store a derivative that reveals \"nothing\" about your password, not even the length. This is done by (amongst other things) applying a certain type of \"hash\" function. From the hash result, you're not able to derive the password, but the same password always results in the same hash. What you do is store the hash result, and when the user logs in, apply the hash to the password entered, and if the results are the same, the password authenticates. \n",
"It has to do with the limitations of the hashing algorithms used to encrypt passwords.\n\nIf your password for a website is \"password1\" the website does not store it as \"password1\" but rather puts it through an algorithm that turns \"password1\" into something that looks like gibberish (e.g. \"@#FV$GSDG%%G#H^\"). This is called a hash. Though it looks like gibberish, only when fed \"password1\" will the algorithm return that exact hash. All other passwords will yield different gibberish. At least this is the ideal case.\n\nThe algorithms that are out there do to this are very complex are hard to create (the good ones are). One of the limitations of these algorithms is that if the password becomes too long, the hash becomes non-unique. Such that \"password1\" and \"areallylongpasswordthatdoesntreallymakesenseforanyonetouse\" might lead to the same hash. This means someone could log into your account with either password. To eliminate this issue they limit the length of the password.\n\nMost modern day hashing algorithms can handle more than 16 characters uniquely. If a website only allows 16 characters they are either using a old algorithm (not good) or they just haven't updated the password validation algorithm (means they are lazy). In either case, it means that they aren't serious about their security. It's ok to use these sites just don't reuse the username or password with a site you are serious about keeping private.",
"Short answer: you're right, longer passwords are more secure than more complex ones. \n\nImportant note: **if a website puts a character limit on your password, it is NOT a secure website and you should not trust it with any important information... Especially not a password that you use anywhere else!**\n\nLong answer: this has to do with how websites store your password. See, storing passwords in plain text is a big security risk, since any security breach would immediately be a breach of EVERYONE'S account. So instead we use a technique called \"one-way hashing\" so a computer can verify your password without ever knowing what it is. Basically, you develop a consistent system for encrypting text, such that it can't (practically) ever be decrypted. With this kind of encryption, every time you encrypt the same text, you'll get the same encrypted output. So you actually don't have to store someone's password; you just store the encrypted version, and try encrypting whatever gets typed into the login screen to see if it matches. This technique was pioneered in the 1960's, and has been a basic security practice for decades.\n\nThat encrypted string of characters is called a hash. In the last 15 years or so, we've started using systems that make fixed length hashes - that is to say, no matter how long your password is, the hash will be the same length. For example, I use 32 character long hashes in one of my applications. Your password could be \"12345\", or it could be the entire script of Space Balls, but the hash will always be 32 characters long. \n\nAny system that uses a reasonable hashing function doesn't care how long your password is, because the hashed version will always be the same length. Therefore, the systems that do limit how long your password is, are not hashing your password. Note that password minimums are important to protect against automated guessing systems. Password maximums are the sign of incompetence.\n\nTL;DR: any website that limits the length of your password is telling you that they don't implement the most basic security practices that have been around for almost 50 fucking years. If that's their system for storing your password, consider it compromised as soon as you've entered it. And if that's their approach to protecting your data, consider your data pretty fucking poorly protected with them.",
"Longer passwords aren't going to be better if they're easier to predict because of having frequent words, frequent word combinations and so on. This is precisely what common password rules try to defend against.\n\nSome commenters have brought up a famous XKCD strip that argues for using common words in passwords. That strip has a big flaw: **it only works if users cannot choose their own password**. If they can the security plummets because users will pick more frequent words and predictable word sequences.",
"It all useless if the site stores the password as plain text. Tip, if a site emails your password when you forget it, run, run away.",
"Yes. Most websites are programmed by people who don't understand the fundamentals of security. That's why all these hacks are such big news.",
"Even a well written site that stores passwords safely as fixed length hashes and uses a type safe programming language that protects against buffer overflow attacks will still have a maximum password length. This is to protect against denial of service attacks where an attacker gets lots of computers to submit passwords that are, say, several megabytes in size all at once. This would stress the servers being attacked by overloading their network bandwidth while these very long passwords are being sent to the server, increasing the memory they require to store all these passwords while their hashes are being computed, and slowing down the calculation of the hashes by requiring the hash algorithm to calculate results on values that are a million times larger than usual. Even if the server doesn't crash it is in for a long period of extremely bad performance where regular users won't be able to log in."
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4ggeu9 | what's actually happening when someone overeats on a regular basis and their stomach "expands"? what about in reverse when their stomach gets "smaller"? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/4ggeu9/eli5_whats_actually_happening_when_someone/ | {
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"It's not just a figure of speech. Your stomach can physically expand/stretch. [Competitive eaters expand their stomachs for competition using water](_URL_0_). It really is like a balloon in a way. The size of the actual organ doesn't change, but it's elasticity and response to food can.\n\nThe opposite is not true however. You cannot shrink you stomach. It is an organ and does not change size. What is happening when your stomach \"shrinks\" from not eating is you appetite resets. You stomach has nerves around the outside that indicate when your stomach is \"full\". Those may begin signaling earlier if you have not eaten in a while."
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40bvjq | rental car insurance. | Are there scenarios where it is beneficial to purchase it when you already have personal auto insurance? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/40bvjq/eli5_rental_car_insurance/ | {
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"When on vacation I had a mid-sized cheap car reserved for me. They tried to get me to get a much more fancy and expensive car. My insurance alone would not have covered the full value of the vehicle. I stuck with the cheapo.",
"I called my insurance company to make sure that my policy is the same whether I'm driving my car or a rental. It does except for what they call \"loss of use.\" The way I understand it, if you crash the rental, insurance will cover damages to it, but the rental company can claim losses because it would have been making them money if it had not been crashed. \n\nI didn't ask the rental company if loss of use was covered with their insurance, but I'm assuming it is. \n\nSo, for me, the answer is not really, unless you're planning to really fuck up the rental. YMMV. ",
"The purpose of travel and location are also factors. \n\nMy personal insurance would cover rental cars for pleasure trips into the US but not if my trip was business. However, I was covered for any trip (domestic) in Canada.\n\nI tried to purchase additional coverage to cover American cars on business trips but the rental car policies were far cheaper for the same coverage.",
"If it's a business trip, and the cost of the rental is picked up by your company, by all means get the additional insurance.\n\nRegarding personal use, I asked my sister who used to be an insurance underwriter. (Most of the time, an insurance agent just looks at charts to see whether you qualify and what to charge you. If the charts don't answer the question, the decision goes to an underwriter at the insurance company.) She never gets the additional insurance.",
"Also keep in mind, that your credit card may also include insurance when used for a rental car. I know VISA has a policy. It's included as a member, is automatic and costs nothing."
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19pzvd | [mod post] coming soon...on rules and mods. | Salutations!
Recently, the moderators of /r/explainlikeimfive sat down together on IRC to discuss some issues we've been having, changes to be made, and the future of this subreddit.
----
We have three things we want to do over the next 1-3 weeks:
* **Rules:** We will be changing the sidebar rules to make them more comprehensive and easier to understand. We want to make the line between good and bad posts more obvious. We already have a rough draft for this, but suggestions either posted in this thread or sent to the mod team directly will be taken under advisement.
* **Moderation:** We still want to remain community-directed as much as possible, both because we want the community to decide its own direction, and because we're volunteers with IRL jobs and responsibilities, which makes it hard to implement heavy moderation of a consistently high-quality.
That said, we will be stepping it up in regards to enforcing the newly expanded rules, and will be removing rule-breaking posts. We ask for the community's help in reporting these to us because, as I said above, we have IRL responsibilities and can't be everywhere on the subreddit at once.
Also to that end...
* **New Mods:** Sometime soon we will be looking into signing on 2-4 new moderators to help with workload and moderation consistency. We do not, as of yet, know how we will choose these moderators. We may ask for applications/nominations, but we aren't sure, **so please do not submit mod applications or requests to us, either in comments or PM** (at least not until we ask you to).
As always, thanks for being a great community.
-Dr_M for the Mod Team
| explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/19pzvd/mod_post_coming_soonon_rules_and_mods/ | {
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"Can we make sure the rules do more to encourage searching for answers first? Especially around big news events, the old classics of '3d printing' and 'schrodingers cat' come up constantly too. A giant red bar that flashes up when you mouse over submit like on askscience or TIL might help."
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2hgrt0 | why are there so many contradictory ideas about what humans should be eating, but other animals are very straightforward in knowing what to eat? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2hgrt0/eli5_why_are_there_so_many_contradictory_ideas/ | {
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"The eternal battle of scientific evidence vs. \"common sense\" dieting vs. weight loss vs. ethical diets",
"We have the technology to make whatever we want and the resources to get whatever we want. We have a lot more choices than an animal does. It also helps that we're omnivores and able to make any type of food digestible and tasty, while many other animals are stuck being unable to digest one thing or the other.\n\nAnimals don't have as many choices, so they stick with what they know and have access to. An animal won't be able to get its hands on much refined sugar or MSG, but if it did, it would eat it until sick.",
"Think of literally every food you have ever eaten, smelled, saw, or heard about.\n\nOther animals get to choose between Dead Thing and Other Dead Thing.",
"Animals generally just eat whatever they can find. They rarely have a surplus of food, so there isn't much of a choice in the matter. If their diet is unhealthy, so be it. Unhealthy is better than starvation.\n\nHumans have the luxury of sitting on their butts and debating endlessly about what food is best to eat because we've got so much of it to choose from. We decide (or tell ourselves we should, at least) what we eat based on what will keep us the most healthy rather than just whatever we can get our hands on.\n\nAdditionally, it's worth noting that most diet-related health conditions people in first-world countries deal with are related to *too much* food. Obesity, diabetes, and heart disease are all caused or worsened by an overabundance of food or parts of food. Animals in the wild rarely have that problem, and usually have the opposite one."
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2vgfo9 | if redbull lost a lawsuit over their "gives you wings" slogan, how do the current commercials still include the slogan without a small disclaimer included? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2vgfo9/eli5_if_redbull_lost_a_lawsuit_over_their_gives/ | {
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"Actually, that law suit (for $13.5 million) was not because of the tagline \"give you wings\" (which is clearly understood as humor).\n\nThe law suit was over the fact that Red Bull oversold the drink's ability to improve concentration and energy, specifically, it did not provide any scientific evidence to support their claim that the drink is \"able to boost energy better than a cup of regular coffee\"--considering that a 8 oz of Red Bull contains less caffeine than 8 oz of coffee, their claim is blatantly false.",
"In Canada there is a verbal disclaimer saying Red Bull does not actually give you wings. Apparently Canadians are not all that bright."
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5adr0l | why does adding salt to desserts make them seemingly sweeter? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/5adr0l/eli5_why_does_adding_salt_to_desserts_make_them/ | {
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"Salt changes the electrochemical reactions that happen in the chemoreceptors on your tongue (taste buds). The effect is different for different types of receptors; bitter receptors are inhibited, while sweet receptors have their sensitivity enhanced. Sweet becomes sweeter and bitter becomes less bitter (but only up to a point; too much salt and you'll taste brine).",
"It has to do with the vast amount of taste buds your tongue has. On these taste buds are different receptors, which only respond to certain ingredients. There is a receptor that was discovered a few years ago that moves sugar into the sweet receptor only if sodium is present (which is half of what common table salt is made of).\n\nSo since you have a pinch of salt, it activates these receptors and helps more taste buds register the \"sweet\" sensation of sugar."
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rtxs2 | why did a law need to be passed telling federal employees that they couldn't participate in insider trading? | I know Obama just signed a law saying congresspeople couldn't participate in insider trading-- were they exempt from the other laws against it? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/rtxs2/eli5_why_did_a_law_need_to_be_passed_telling/ | {
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"This is how I understand it. Can someone please fill in the details or correct me on this?\n\nPart of the reason is because, technically, a lot of what they were doing wasn't \"insider\" trading. Typically, insider trading happens (e.g.) when you work for a company or are someway involved in a company and you happen to know that your company did something good, so you and your buddies buy up a bunch of stock in advance of that public knowledge. There are other ways, but basically it's when you or someone you know has knowledge \"inside\" of a company.\n\nThere's plenty of that that went on in Congress as well, and still will. But what was happening was that Congress itself was the \"insider\". It knew it was about to pass a law that, say, hurt companies X, Y, and Z. So they took that knowledge and sold their shares or \"shorted\" them to make a profit off this knowledge.\n\nTechnically, this didn't have anything to do with having \"inside knowledge\" of a company's performance, financials, etc, so it was legal. It's still wrong, though, because it gives lawmakers a financial incentive to make laws one way or another that benefit them financially."
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2ci7me | the future of computer storage: storage capacity vs compression abilities | So we're seeing increasing sizes of HDDs and memory sticks, but I'm wondering if the sizes will just continue to increase, so that in 5-10 years, will we have 1tb mini usb sticks (sure, they probably allready exist, but they arent cheap yet, like the 16gb ones...) OR will we see more progress in compression and things like that so high quality files will take less space? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2ci7me/eli5_the_future_of_computer_storage_storage/ | {
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"There is a mathematical limit to how much data can be compressed, and there's an entire field of math (called Information Theory) dedicated to studying it.",
"So far, capacity has kept increasing rapidly. You used to buy the biggest drive you could afford, knowing that it was going to be filled up all too soon anyway, but that you'd be able to get a bigger one in a few years.\n\nThese days, the capacity of a hard drive tends to be much larger than anyone needs, especially with the offloading of capacity to the Internet. You can get your movies and songs online, so they're not eating your disk space.\n\nFiles are more typically compressed to reduce bandwidth, now, so they don't eat too much of your data line, although it's also still handy to reduce storage space. There's always this trade-off with compression, is the problem. It takes time to compress and decompress data.\n\nI'd bet on drives getting larger and cheaper for the next decade or so. Barring a massive improvement in computer speed (unlikely) or cool new developments in compression algorithms (also unlikely), \"more space\" is still relatively easy at the moment."
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2n2dzk | why is vibrato singing considered good? | I hear a lot of professional singers (mainly female) who all sing with very prominent vibrato. To me this feels like they just can't hold a solid note. | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2n2dzk/eli5_why_is_vibrato_singing_considered_good/ | {
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"It's a very difficult skill to learn well, and much much harder than holding a steady pitch, at least to do it with smooth even control. Having said that it's an aesthetic choice, people do it because they like it, and because it's a bit showy to use a difficult to achieve skill in a prominent way.",
"Long notes can sound boring. Vibrato is intended to add some colour and variety during the course of the note.\n\nVibrato is a skill... but an equally important skill is knowing when and how to use it. It probably shouldn't be used in every note, or for the whole length of the note. The speed and the intensity of the vibrato can and should be varied, between as well as during notes. Basically, it shouldn't be predictable or boring, or else it defeats the point of using it in the first place. \n\nEverything I've said here applies to pretty much all instruments on which vibrato is possible, by the way, not just voice."
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5tjo00 | how were length/liquid measurements kept the same everywhere? | As in, if this is right: _URL_0_
How did they keep the length of an inch the same everywhere, if they didn't have the exact same 3 pieces of barley nor was a man's belt the same to determine every yard.
Or how did they keep the measurement of a pint the same every place. How would they even create an exact container each time that represented the correct amount of liquid each time. Did they just pour the liquid from one container into another and go from there?
Specifically in ye olden times before mass production was a thing.
| explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/5tjo00/eli5_how_were_lengthliquid_measurements_kept_the/ | {
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"The short answer was, they didn't. Standards varied heavily from region to region. Keep in mind, back then, travel/trade was *a lot* harder, so the effects were much less noticeable.\n\nIn some cases, once things were more developed, they would have a standard- then they'd copy that standard and ship them around the world. But usually they were just really inaccurate.\n\nIf things were really really off, someone might call you on it, but slight variations, how would they know?It wasn't really until the industrial revolution and standards started being really important did things really start to kick in- largely driven because that's when it mattered"
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272e3x | how does paypal make money/stay in business? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/272e3x/eli5_how_does_paypal_make_moneystay_in_business/ | {
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"If you sell something on Paypal, you have to pay a certain percentage of the transaction to Paypal.",
"If you are a merchant selling something through them they take a 2.9% + $0.30 cut of your profit.",
"It takes a number of days to get your cash out of paypal and into your back account.\n\nDuring these days paypal deposits the money into an account which earns interest. Imagine the quantity of money they process and you get the picture ",
"While I doubt this is how they make most of their money, getting your money back if there's something wrong with your account can take ages..\n\n"
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3p0myn | you know how you can tense up certain muscles in your foot or leg and pretty immediately give yourself a cramp? why do your muscles have those 'pressure points' or non-random cramp areas, and why is it so easy to bring about a cramp in them? | It seems like parts of my body are on a hair trigger, waiting for me to make that one right move, and lock up. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/3p0myn/eli5_you_know_how_you_can_tense_up_certain/ | {
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"I tried to read up on this, and also asked my doctor about it, and it seems to not be totally known, in part because there can be a lot of different reasons depending on the person and circumstances.\n\nI think these are usually technically muscle spasms rather than cramps, although they're similar.\n\nSome possible causes:\n - Dehydration\n - Electrolyte depletion (usually salt, sometimes potassium and maybe magnesium)\n - Muscle overload\n\nThat last one is probably what's going on -- it seems like it is most likely to happen with highly underused muscles (or overused muscles in people who work out a lot)\n\nOf course there are also (a zillion) medical conditions that can cause cramps or spasms.\n\nGoogling found this page that looks ok at first glance:\n\n_URL_0_"
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2oqb4i | how can the hubble space telescope keep its lens pointed in the same spot to take long exposure shots when it's orbiting the earth every 97 minutes? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2oqb4i/eli5_how_can_the_hubble_space_telescope_keep_its/ | {
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"It does not take a continuous exposure but rather multiple exposures that are then stitched together.",
"Don't forget that while the Hubble is moving around the Earth, Earth is moving around the Sun. And Sol is moving around the Galaxy. And the Milky Way is moving around inside Laniakea, and....\n\nNothing involved here is staying still, or in the same spot.\n\nBecause it seems like your question is based on the assumption that Earth would obscure the lens of the Hubble for half of that time every 97 minutes, imagine that the Hubble orbited around the equator and was looking North with respect to Earth. From this orientation, Earth would never obscure the image or disrupt the long exposure.",
"The objects it points at are so far away, that the rotation around the Earth is negligible.\n\nFor instance, Andromeda is 1.49196325 × 10^19 miles away. The Hubble telescope is at an altitude of 347 miles, so as it moves around the Earth is moves roughly 8620 miles from one side of the orbit to another.\n\nUsing trigonometry, we know that if Hubble looks at Andromeda, that means it's angle changes roughly 3.3116961 x 10^-14 degrees (arctan of ((8620/2)/1.49*10^19). \n\nWritten out, that is 0.000000000000033116961 degrees, or basically negligible in this case.\n\nMy hand moves more degrees than that when I take a selfie in the bathroom, but it doesn't distort the image because the change is so small.",
"Hubble uses six gyroscopes to know exactly where it's pointing. These are devices that act a bit like a compass, and always point in the same direction even when the telescope is orbiting.\n\nNext it has four reaction wheels which actually move the telescope. These just use Newton's 3rd law of motion; if the wheel spins one way then the telescope spins the other.\n\nFinally when it's observing, an instrument called the Fine Guidance Sensor will lock on to nearby stars, and make sure the telescope stays precisely pointed in the same direction/orientation.",
"If you're thinking of images like the [Hubble Deep Field](_URL_0_) then that was actually made by combining 340 pictures of the same point in the sky rather than a single long exposure.",
"Just in case you weren't asking about the earth obscuring the image cause it's in the way for about 1/2 of the time - pick up a pen and make a fist, point the pen at something in the room then orbit the pen around your fit so the pen is always pointing at the object. This is how things orbit naturally, their own spin is independent of the object they are orbiting. Yes, the earth obscures the images, but the shutter isn't open the entire time - it'll close and reopen later on when the earth is out of the way but still be pointed at the same spot. Also - each exposure may only be a few minutes long but there will be many exposures and each image is stitched together with computers so they all line up."
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8w9efx | what do fireworks event companies do the rest of the year? how do they stay profitable? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/8w9efx/eli5_what_do_fireworks_event_companies_do_the/ | {
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"Sporting events mostly. A lot of minor league baseball teams have displays at the end of weekend games. Same with other sports as well. "
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emhktu | what is computer science? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/emhktu/eli5_what_is_computer_science/ | {
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"When computers were first built and people came to realize how powerful they were, they needed people to figure out how to make them work and how to make them better. The original designers tended to be mathematicians, physicists, engineers, etc. but no one field could really do it all. Computer science is sort of the catch all term for the people who ended up working on computers, both more theoretical and also applied.",
"So, this rundown is my own, and the idea here is to have a pseudo-historical list running in descending order of abstraction. Basically, I'll start with the most abstract and general ideas of the field, and work down towards nitty gritty practical bits that emerged.\n\nBut anyway, the main idea of computer science is to deal with processes, and specifically, unlike mathematics, processes that have extra limitation that you need to be able to perform them in a finite amount of time and space. Because, you know, humans have only limited amount of time to wait for computation to finish, and there's only finite amount of the universe we have access to.\n\nSo, in computer science specifically, what was a rather important point was that sometimes you have these processes be in the form of step-by-step lists of instructions(hereby called \"algorithms\") that even the stupidest could follow. So we built the stupidest thing, and we called it artifical computer(as opposed to computer of the old, who were humans, mostly women, performing calculations as required for some fields of science and engineering and such), and tried seeing what we can do with this concept. So now the question of study became, what can these artifical computers actually do. Some major results were achieved in 1940's, specifically Alan Turing was helpful, where he managed to prove some key things about things that can be computed, and perhaps more importantly, that there were some things that couldn't.\n\nAnd as computer technology advanced, computers itself started to become more complex, and the programs running on them started to require more and more sophisticated thinking, and computer science basically absorbed things like software engineering to itself, taking it further away from pure math world. Things like, what sort of tradeoffs you'd have when designing operating system fit neatly in this world of questions that more or less deal with what can and cannot be done with computers.\n\nBut much of the discussion is still well within confines of pure math as well. Say, computational complexity is a measure of algorithms ability to use fewer steps to arrive at the right answer. You don't need to ever even have seen a computer to be able to answer questions about those kinds of things, and it's ultimately about processes and algorithms rather than this physical device, although limitations of this physical device did end up sparking interest in these types of questions. Likewise, \"formal language theory\" is basically mathematics, but that theory is the main way to understand programming languages, and the theoretical foundation for their existence. So the line gets blurred. I'm unsure but I believe linguistics also makes an appearance here in this multi-dispiclinary mess. Another field that I want to highlight for math'iness is artifical intelligence. Also, worth noting that encryption basically is just taking mathematical problems we can prove are hard in one way but easy in another.\n\nAnd then you also have fields that are more specifically about using computers, like user interface design, or user experience design, which start invoking psychology and such things.\n\nAnd obviously, physical design of computing devices with its electrical engineering, physics and chemistry connections has to be mentioned.\n\nBasically, it started out with a rather simple premise of \"what this box do?\" and then when the box turned out to be very powerful, the field just exploded to cover everything the box touched."
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1ciok3 | when i wake up at 3 am to pee, why does keeping my eyes closed for my trip to the bathroom seem to help me get back to sleep faster? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1ciok3/eli5_when_i_wake_up_at_3_am_to_pee_why_does/ | {
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"Your brain has this thing called a circadian rhythm. What it's designed to do is make you sleepy at night time and wakeful during the day. Unfortunately, your body doesn't have a clock inside of it so it has to rely on cues outside of you to know when it's night and when it's day. One of the cues your body uses is light. When you see a bright light at night (awesome sentence) it confuses your brain and makes you more awake. \n\nNote: This is a big simplification but you get the idea."
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1ilapa | how do they move sculptures that are to big for trucks? | Phone won't let me do just a title, pay no attention to this.
Edit: ah dicks, forgot ELI5 | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1ilapa/how_do_they_move_sculptures_that_are_to_big_for/ | {
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" > Edit: ah dicks, forgot ELI5\n\nHa. It's ok. It's still evident this is a legit ELI5 question.\n\nI really wish there were a better answer, but they pretty much just [close down all the roads](_URL_0_). It's super inconvenient (which is why they try to do it late at night).\n\nLA has something of a habit of frequently inconveniencing its citizens by bringing in massive boulders, sculptures, and even space shuttles."
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3jqxct | how can an aircrafts engine work at such high altitudes where humans struggle to breathe due to lack of oxygen? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/3jqxct/eli5how_can_an_aircrafts_engine_work_at_such_high/ | {
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"The aircraft require less power at high altitude because of less air resistance but very few aircraft can operate at very high levels due to the lack of air.",
"The plane does indeed need a *lot* of oxygen from the air. The front of the engine has *compressor fans* which suck in huge amounts of air and squeeze it much more densely into a small space farther back in the engine, where it is actually used to burn the fuel.\n"
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43zrok | why does the western world (say usa and western europe) get involved in armed local conflicts all over the world even if it doesn't have to? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/43zrok/eli5_why_does_the_western_world_say_usa_and/ | {
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"Poland is western Europe now, hurrey ! :D\n\nfor serious - geopolitics - you cover your interests, secure more allies, resourcers or markets, sometimes it aligns with higher goals like human rights.",
"Humanitarian missions, formal appeals for foreign military intervention, personal financial investments into regions, political/tactical importance of the region/government they support/fight against. But often in modern times it's been mostly in response to protect lives in response to growing terror organisations. In the cold war era, it was often a battle of communism vs capitalism that required the west to step in to stop the spread of communism and perceived evil. Sometimes it's because of military alliances. It's really hard to give you a definitive answer without a specific example.\n\nBut your assertion that it's only the western world that does this is wholly wrong. The difference is that when the west does it - they're more or less transparent about their presence/reasons for doing it. Asian countries such as India, China and Pakistan have done it before, middle-eastern countries are too unstable in their own regions, so they often don't intervene anywhere else, but they have fought multiple wars in the span of a few decades against each other, so have African countries and African countries often involve themselves in ongoing wars within other African countries to \"Aid\" their allies. Russia has done it multiple times as well. It's just that those countries are the strongest and most stable politically/militarily, therefore they can allow themselves to involve themselves into wars without a risk of destabilising their countries.",
"Several reasons. \n\n1) We have interconnected economies. So having trade access to resources means that some conflict that you would not think would affect a country really do affect them. \n\n2) We now have invented weapons that are capable of destroying civilization as we know it with a push of a button. Limiting who gets the knowledge to make these weapons, and watching those countries that do have the knowledge is important and it often means going into war or smaller conflicts to prevent the spread of that knowledge. \n\n3) Much of the world powers attempted to practice the philosophical stance of letting countries do whatever they want in their borders and to their neighbors and only getting involved when there was direct threat to them. What happened was the build up of Germany and start of WWII. ",
"long answer: military industrial complex\n\nshort answer: money\n\nAnyone who says we're oversees for humanitarian reasons is most likely a moron. Think of international politics as a game of civilization. Every world leader is trying to get by with whatever resources they have and there are those few dickheads that got lucky with extra science and production and go around screwing over everyone they can because they can.\n\nSure there are humanitarian efforts, but usually the problems these efforts are fixing are directly related to issues our meddling created in the first place.",
"I'd say as well as the other reasons the dudes have given, there's a lot of partnerships and treaties that the western world are part of, which mean that they sometimes need to go to war to uphold them",
"Polemologist here.\nThere is a number of reason which can be summarised as follows (not necessarily sorted by importance:\n\n1) Ethical duty and R2P (Responsibility to protect). \n- > Something bad happens. You want to help the victims / affected.\n\n2) Globalisation.\n- > Interconnectedness of economies. If others have problems, you may have problems in the future.\n- > \"Failed States\". If things get too problematic in a given country terrorist groups or criminals may proliferate and establish themselves in the given country and sequently, from there, target other countries. It is better to prevent an escalation.\n\n3) Diplomacy.\n- > There are a number of international agreements that define how countries can and should help each other in certain situations, even if not directly interested by a particular conflict. \n- > Blowback and intelligence / diplomatic actions. They can be good or bad. If a diplomatic action or intelligence field operation goes wrong you can become a target. Accordingly, even if you had no interest in getting involved, you have to reply, or be ready to jeopardise your \"reputation\".\n\n4) Maybe the most important. The \"Western world\", has to do it. for the above reasons, and a number of other concepts, we are affected by conflicts far away. \n\nIf you want further informations about this look up \nBalance of Power\nGlobalisation\nEconomic interconnectedness\nR2P\nBackground _____ (insert any conflict here, and the reasons why we intervened will become clear).\n\nIn particular, the book \"Resource Wars\" By M. Klare, explains quite well the war in Iraq. Specifically, addresses an audience with little to no knowledge of international affairs and explains the reasons why all the events happened. SPOILER: of course oil is involved, but to fully grasp this kind of events you must be open-minded. ",
"It doesn't. It frequently ignores far worse humanitarian situations, where it could have far more positive impacts. The West/Russia/Iran get involved in conflicts where it is either:\n\na) In their geopolitical interests to do so,\n\nb) In the local political interests to do so, or\n\nc) To get themselves/people they are linked to money.",
"There are a lot of geopolitical benefits on top of the economical and moral obligations the US assumes as a top military power. When the US intervenes in a non-democratic country they gain strong political influence, establishing a country's new democratic system and quite possibly selecting who gets the presidential nod. Our involvement in the Middle East is strongly tied to ridding the world of terrorist groups, dictators, oil, and establishing a strong political ally inside a dangerous region. ",
"Many of the concepts here briefly touch on it but in political science, this is referred to as the Role of Hegemon. It works, but you basically hope that the entity in charge is sane and ethically acting and that they're the best when considering the alternative.\n\n\n1) is a theory of international relations, rooted in research from the fields of political science, economics, and history. HST indicates that the international system is more likely to remain stable when a single nation-state is the dominant world power, or hegemon.\n\n_URL_0_",
"To take a less cynical view than most comments. Look at the issues with refugees in Europe, which in turn is messing the world economy up. It may well have been cheaper to get involved very early and wipe out Isis and or Assad than deal with all this. ",
"Lots of good answers here. One thing I've noticed is the US tends to stay out of problems nearby. My guess is because risky military operations far away have a low chance of direct attack in response.",
"Here's your ELI5: Because it's easier to oil an engine than it is to fix one. Civilization needs a well oiled engine to progress. ",
"I'd label it as a side effect of the NATO system which basically exists to shut down future world war scenarios. If you look at NATO as a hegemony with the US at its head, you have a system where they quickly turn into political firefighters. You really don't want anyone who has the potential to fuck with the hegemony (China, Russia mainly,) to feel like you can't keep any of your metaphorical fingers from getting cut off. You make sure you don't get burned, that way you look more like you can't be burned. ",
"The US is about 4.4 percent of the world's population, but we in America have grown accostumed to consuming about a quarter of the world's energy resources (coal, oil, natural gas). \n\nSince we don't actually produce a quarter of the world's energy resources, we must continuously exploit numerous resource producing nations in order to maintain our ever increasing appetite for consumption.\n\nCouple that with a capitalist economy, which absolutely relies on ever increasing growth, it naturally follows that we will be perpetually involved in conflicts abroad in order to both secure resources and to increase profits for our companies. \n\nThis is what every empire in history has done or has tried to do."
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97l9hr | why is perpetual energy from gravity impossible? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/97l9hr/eli5_why_is_perpetual_energy_from_gravity/ | {
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"Gravity pulls things down. You can exploit this for energy, but only once.\n\nOnce the object has exhausted its \"gravitational potential\" (i.e. hit the ground) you can't extract any more without first picking it up again.\n\nWe do extract energy from falling water in hydroelectric dams, but again the water can only pass the dam once.",
"Because all of the energy produced by the system must invariably be reused to provide the potential energy used for the next cycle. The amount of energy you put into moving the rock up the hill is equivalent to the energy released when it rolls back down. The result is that you'll never get more energy out than you put in. Then throw in entropy generation as a constant bleed-off of useful energy due to inevitable inefficiencies, and you'll always be operating at a net loss."
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3vfjz8 | how do people get hd clips from tv to the internet? | I know it's probably super simple, but I was curious as to how people are downloading/streaming TV and then making clips to put on YouTube or making GIFs.
Thank you! | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/3vfjz8/eli5_how_do_people_get_hd_clips_from_tv_to_the/ | {
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"A PC with a \"Capture Card\" of one kind or another.\n\nHD material from a cable/satellite box gets fed into the computer, where it's \"captured\", and can then be edited and uploaded. It's not legal, but it is rather easy with modern software."
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16ss7m | degrees of education | What is the difference between a bachelor's, master's, doctoral's, Ph.D., etc.? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/16ss7m/eli5_degrees_of_education/ | {
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"Associate's Degree: 2 years \n\nBachelor's Degree: 4 years \n\nMaster's Degree: Bachelor's + 2 years \n\nDoctoral/Ph.D: Bachelor's + 4-6 years. ",
"A bachelors degree is usually a four year degree at a university. While doing this you can consider yourself an undergrad student. A masters degree is obtained after earning your bachelors and applying to and being accepted to graduate school which may or may not be offered at the same university that you got your bachelors degree at. A Doctorate and a PhD are essentially the same thing as far as I know and they are the next step after a masters degree. Obtaining a PHD in a field requires original research of your own in a field of your choosing. "
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23apur | why has easter turned into a time to celebrate finding chocolate/eggs from a bunny? | In all honesty i don't get how they relate | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/23apur/eli5why_has_easter_turned_into_a_time_to/ | {
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"You might ask why did Easter turned into a Christian holiday \"celebrating\" the torture and death of their god when it is actually (and originally) about the Spring Equinox and fertility.",
"They don't.\n\nDecorating eggs seems to be a festive activity dating back to antiquity. The rabbit, or the hare, was a common symbol in Christianity, and European culture in general.\n\nThe practice seems to come from German Protestants, who rejected the Catholic practice of fasting during Easter in favour of continuing to dye and eat eggs. Given that eggs were prohibited during Lent, this also made them significantly cheaper, so it has a semi-practical explanation.\n\nLike a lot of things, German practices came into English practice through the royal family, which was 'imported' from Germany in the 17th century, when George I ascended to the British throne.",
"Like every christian holiday it is actually a pagan holiday that predates the invention of Jesus. The eggs and the bunny are symbols of fertility that have absolutely nothing to do with christianity. They come from the festival of Ishtar. An ancient pagan festival that was folded into christianity by Constantine. "
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7i45d5 | how was the internet made? like how did they discover coding, etc? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/7i45d5/eli5_how_was_the_internet_made_like_how_did_they/ | {
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"Computers predate the internet by several decades, but the origins of the internet can be traced back to a US Military project in the 1960's called Arpanet. They wanted to see if they could get computers to communicate with each other. The first data packet was sent from a computer at UCLA to one at Stanford in 1969. The technology that came out of Arpanet ultimately led to the commercial internet."
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b4r8ll | why does the burn of putting your leg in hot water seem to come a second or so after it’s been pulled out? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/b4r8ll/eli5_why_does_the_burn_of_putting_your_leg_in_hot/ | {
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"So there’s ‘two’ nervous systems that usually work together. This is an example of where one takes over first.\n\n- CNS = Brain. It controls the actions you think about so it takes longer to work.\n- PNS = No Brain. Controls reflex actions, ones you don’t have to think about, so it’s faster.\n\nThe leg in hot water reaction would work something like this:\n1. Leg goes into water\n2. PNS realises you are in danger.\n3. PNS moves leg out of the water because it knows you’re in danger.\n4. CNS realises leg is out of water\n5. CNS realises leg is in pain and lets the brain know, meaning you only then feel pain.\n\nI hope that’s simple enough, ask any questions if you need clarification.",
"I don't think the other answers really get to the root of the question. You have different types of nerves. Big nerves and little nerves, insulated and non-insulated nerves. Big nerves are fast. Insulated nerves are fast. There are two types of pain nerves, and both are small (one is insulated, the other is not). \n\nAs for why you move your leg: the nerves send a signal to not just your brain but also special nerves that live in your spinal cord. These nerves (called interneurons) \"short circuit\" the system with a \"reflex arc.\". It sounds confusing, but what it means is the signal going up to your brain is always diverting just a bit to nerves that can make decisions without the brain of they hit a danger threshold to protect the body. It is the same system you see when doctors tap your patellar tendon at your knee (the brain kinda turns these off, and when you have an interview to the spinal cord, there is no off signal.... Just an on signal)",
"The central nervous system (CNS) is the brain **and** the spinal cord. The peripheral nervous system (PNS) is all the nerves that come off the brain and spinal cord (like in your arms and legs). Nerves are the way information in your body is communicated around (like a network).\n\n1. When your leg touches the hot water, a nerve in your leg 'senses' this heat and passes the info to your spinal cord (because that's where that nerve is connected to).\n2. In the spinal cord, this 'sensing' nerve passed the info to a 'moving' nerve.\n3. The moving nerve is connected to your leg muscles and when it receives the info, it makes the leg muscles move your leg out.\n4. At the same time that step 2 and 3 is happening, the spinal cord is sending this information up to your brain for you to process. By process, I mean 'feel' the pain and scream.\n5. Because it takes longer for the information to reach your brain than to go back to your leg (literally just compare the distance from leg to brain vs leg to leg), steps 2 and 3 will happen quicker than step 4.\n\nFor a bit of terminology, we call this a 'spinal reflex'. This means you don't actually need your brain for this reflex to happen, it just needs to spinal cord. But our brain is there to process the info so we know next time not to put our leg in the hot water because it will hurt like hell.\n\n & #x200B;\n\n & #x200B;",
"Oh man!\n\nNone of these cover the real reason it **burns** when you take it *out* of the water rather than why it takes a while to feel. It's super interesting!\n\n\nIt burns because of the mixture of hot and cold feeling in the same area at the same time. \n\nThe body has pressure and temperature sensing nerves. **But the body doesn't have a way to sense burns. Instead, it senses hot and the feeling of nerves not being able to send any signals because they're dying — which happens to feel like cold.**\n\nTry this experiment:\n\n*Take out 2 butter knives. Run one under cold water and the other under hot water for a few seconds. Feel the full back of each on the underside of your forearm and notice the sensations: hot and cold right?*\n\n*Now put both knives side by side so the flat parts are close together and touch the dull backs to your forearm at the same time. You haven't hurt yourself — but notice that it feels like it burns!*\n\n\n\nSo when you pull your leg out of very warm water, what happens? The warm water starts rapidly evaporating a few seconds later. And evaporating water — just like sweat, cools down your skin sending the cold sensation at the same time that deeper parts of the skin are still sending the hot sensation. Just like the two butter knives, it feels like burning. \n\nCool right?"
]
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ar47hf | why are commercials so bad? why dont companies hire comedians or any other kind of professional to create commercials for them? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/ar47hf/eli5_why_are_commercials_so_bad_why_dont/ | {
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"Cost. Using big stars or producers is expensive, add on the cost of the time slot for the commercial and it cuts into company money.\n\nThe smaller the business, the lower quality production",
"Great minds think alike. Ahoy, matey! Yer not alone in askin', and kind strangers have explained:\n\n1. [ELI5:Why are there so many bad commercials? Aren't there teams of expert marketers who sign off on them? How can so many people approve something so bad? ](_URL_2_) ^(_58 comments_)\n1. [ELI5: Why can companies with massive advertising departments, like Geico, not realize that their commercials aren't funny? ](_URL_0_) ^(_ > 100 comments_)\n1. [ELI5:why does local media (especially commercials) look so bad compared to national? ](_URL_1_) ^(_8 comments_)\n"
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[],
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"https://np.reddit.com/r/explainlikeimfive/comments/20513k/eli5_why_can_companies_with_massive_advertising/",
"https://np.reddit.com/r/explainlikeimfive/comments/35uaht/eli5why_does_local_media_especially_commercials/",
"https://np.reddit.com/r/explainlikeimfive/comments/40u7us/eli5why_are_there_so_many_bad_commercials_arent/"
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1ey8lm | why is the water contained in a source like soda any less beneficial? | It makes sense there are bad contents in some things but no sources ever give credit towards water intake to anything except actual water. | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1ey8lm/eli5_why_is_the_water_contained_in_a_source_like/ | {
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"I cant really tell what you are asking, the title is confusing.",
"Soda is > 90% water (probably 98% or so). If you want to drink 8 glasses of water a day, 8 sodas would do it but the sugar and sodium would be terrible for you're health. Someone who says they don't drink any water, just soda, or that drinking soda doesn't count as water has no idea what they're talking about. It would be like saying you're not eating beef if you eat a hamburger. ",
"Water is good. Water with a small amount of sugar is better, your body can start using it faster.\nSoda has water and bad things in it. Water is better for than drinking water with bad things in"
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5b4l98 | how are some mods in gaming compatible to new game versions while other mods need to be updated? (eg. skyrim - compatible after patch but minecraft - mods need updates) | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/5b4l98/eli5_how_are_some_mods_in_gaming_compatible_to/ | {
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"It depends on what those mods were doing to the game files, and what was changed in those files between versions.\n\nFor example, if you alter the \"running speed\" value in the movement script, it's not likely the company is going to change the way movement works between versions, so your mod will still work.\n\nFor a counter example, if you use a mesh or model reference, or change a script for object physics, when the new version is released with updated models and textures, or new things that use/affect the physics script, you're going to need to change your mod.\n\nIf you don't, you may end up with any assortment of bugs:\n\n* invalid texture/models, and so your stuff just doesn't show up (animations don't work, invisible objects, clipping through things, etc)\n\n* your mod to the physics script breaking (your fireball now throws upwards. not where the camera is looking)\n\n* your mod breaking the new changes to physics (walking off a ledge on a horse results in their flying)",
"I mod for skyrim so I can explain why the updates don't effect skyrim can't really speak for mine craft \n\nIn skyrim the game is composed of many files called esp (elder scrolls plugin) now the main game and the DLCs are in their own versions of esps and when you open the game it loads the main game first and then the dlcs. Then it loads the mods on top of those files in the order that you set the mods to load in. When a file or any part of the game is modified it takes the form of the most recent load. So if I have 3 different mods for an iron mace only the last one will be used. ( it's a little more complicated than that but you get the point) this mean that any conflicts between versions and stuff are usually just handled by load order. \n\nThe other thing is you can have a lot of errors and stuff that just does not make sense from a computer science standpoint in your mods and the game will mostly work fine. This is evidence by the amount of bugs in Bethesda games. ",
"It depends on how the modding is accomplished. If a game is designed to read in a lot of settings from text files, it can usually be modded just by changing those text files, and doesn't know the difference. When the developers update the game, in order for it to continue working correctly, it must still read in the text files in more or less the same way, so the mods will usually keep working too.\n\nIf a game is designed to load big chunks of computer-readable instructions (binary) into memory, modding can usually only be accomplished by figuring out what those instructions were (decompiling), creating a file that modifies them (patching), and re-making that big chunk of slightly-altered instructions (re-compiling). But the big chunk contains a lot of very specific things like 'go to location #100045644 in memory and do something with that information'. Those specifics are too tedious to make by hand, so the tool that creates them (the compiler) hands them out first-come, first served. That means that even the tiniest update can change many or even most of the specific instructions by bumping things down the line. Continuing the example above, if the update requires the game to remember something new, since memory locations are handed out first-come, first served, that same instruction might now need to go to location #10004564**5** because the information it works with got bumped down the line a little bit. That means that the mods have to be re-built again to re-align their instructions to match the ones in the updated game.\n\nSkyrim is an example of a game that works mostly by reading in configuration files. Minecraft works mostly by loading binary chunks into memory.\n\nYou might wonder why the compiler doesn't try to keep things easier to find, and the answer is that it thinks the code is private, something that will never be accessed by anyone but itself. That is, binary code-injection mods are basically hacking into the program to change what it does in a way it was never designed to allow. Sometimes the original developers are okay with this even though it wasn't planned or supported, other times they're not.\n"
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2hhckf | what exactly happens to your skin when it reacts to posion ivy? | I have a nice little patch of it on my arm and I've just been staring at it too long. | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2hhckf/elif_what_exactly_happens_to_your_skin_when_it/ | {
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"It's called a type IV hypersensitivity reaction, more commonly known as an allergic reaction. This is a special type of allergic reaction that is not caused by histamine like most allergies are. This type of reaction is due to T cells attacking your own cells because they have an antigen (poison ivy) in them and your immune system thinks that it's a virus or bacteria. The end result is that your immune system ends up attacking your own cells, which activates the inflammatory response, which is what causes the redness and itchiness. \n\nOne thing to note is that you need to be sensitized in order to have this type of reaction. That means that you brushed against some poison ivy at some other time and that \"activated\" your immune response. Since it has now been activated, the next time you come in contact with poison ivy, you will get the associated dermatitis. \n\nEdit: Sorry, I forgot to mention this. Cortisone should help with the itchiness and inflammation. Antihistamines won't do shit. ",
"A poison ivy rash is an allergic reaction. There's this stuff in poison ivy sap (poison oak too) called \"urushiol\" that about 85% of people happen to be allergic to. When this sap gets on you via the plant or something the plant has touched, it is absorbed through your skin and into your body. Your body begins to break it down, but due to some fluke of evolution (maybe - the science behind this is still being studied), the immune cells that are constantly checking for foreign invaders recognize urushiol as a threat. This is despite the fact that poison ivy itself does not contain any substances that are \"poisonous\" or that should harm your body.\n\nAnyways, the immune cells basically instigate dermatitis, the body's response, by sending signals that call white blood cells to the scene. The white blood cells eat/break down foreign substances, but in the process they also damage your tissue.",
"The Urushiol oil bonds to the cells and your immune system say \"what the hell is that?\" and attacks. If you get it, and this is probably really bad for you, take a shower as hot as you can stand with the water hitting the rash. We call it an Oakgasm"
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5dqmd7 | resting membrane potential. why it hyper/hypopolarizes? | I'm taking an A & P class where we are currently learning about resting membrane potentials and I am completely lost with a quiz on Tuesday... I am being asked to explain what happens when there are increases or decreases in extracellular potassium concentrations and the same for sodium concentrations, but I don't completely understand. What type of changes are caused? What are the effects of changing the amounts of K+ or Na+ and what is the reason why?
Thank you to everyone for your time in reading and helping answer my questions. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/5dqmd7/eli5_resting_membrane_potential_why_it/ | {
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"The potassium and sodium ion concentrations are what cause the neuron to fire. Or actually they allow the action potential to propagate along the nerve.\n\nA nerve cell starts off polarized,meaning the outside of the membrane is positively charged and the inside is negatively charged. the outside contains excess sodium ions the inside excess potassium ions. For the action potential to propagate a stimulus reaches the neuron, which opens gated ion channels allowing sodium ions to rush in which start the depolarization of the neuron. At a certain point the depolarization becomes an unstoppable wave as the gated ion channels all along the neuron open and sodium rushes in. this is the threshold potential. The neuron is completely depolarized and the signal transmitted. \nAfter the cell is depolarized gated ion channels on the inside open and allow potassium ions to flow out. Restoring the polarization but now by a different ion balance. At a point more potassium ions are on the outside than sodium ions on the inside and the gated ion channels close.This causes the membrane potential to drop below resting potential and is said to be hyperpolarized. During the following refractory period ion pumps restore the original ion balance and the nerve cell can't transmit during this period."
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379ulx | do people in other countries have the same view of the moon that i do if we look at it at the same time? | I live in the United States, and right now the time is 21:18. I just went outside and I could see about half of the moon. For people that live in Western Europe, it is about 03:18 right now, so still pretty dark. If someone over there went outside right now, would they have the same view of the moon that I do?
If my understanding is correct, clouds are covering the other half the moon right now. If someone from Western Europe were to go outside at the same time that I do, would they have the same view of the moon that I have, or would they possible see a full moon or even no moon at all? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/379ulx/eli5do_people_in_other_countries_have_the_same/ | {
"a_id": [
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"Because the moon is tidally locked (the sun only shines on one side at any given time), only one side of the moon is illuminated. This is why we had to send spacecraft to the far side of the moon to see what it looked like.\n\nIn other countries, the moon may be in a different position in the sky due to its position on Earth, and because of the angle the moon may seem to look different, but the part of the moon you can SEE (as in the part that is bright) is the same. "
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5jlyyy | why is it now 4k and 8k instead of 2160p and 4320p | [deleted] | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/5jlyyy/eli5_why_is_it_now_4k_and_8k_instead_of_2160p_and/ | {
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"Well, for one thing, it's easier to say, and easier to remember. \n\nBut I believe the real reason is that using the horizontal pixel count a more consistent number to use over vertical, since number of vertical pixels changes according to the aspect ratio of a movie, e.g. 1.78:1, 1.85, 2.35:1, etc all have a different height in pixels. yet the same 4K of horizontal resolution. Indeed, this is what they use in digital theaters now; 2K, 4K, 8K. \n\n In the days of old, that didn't matter - everything was 4x3 or 16x9, and movie's original aspect ratios were an afterthought. But we've moved more and more towards home theaters and watching movies, it just makes sense to normalize the terminology with what they use in the cinema world.\n"
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2kgrn8 | why don't artists just release their entire album as singles to increase chart performance and song sales? | In the digital age of music, songs are a la carte anyway. I could buy a non-single without buying the full album. So why not release every song as a single? "Bad" and "Teenage Dream" released almost every single song as a single, and those two had some of the best chart performance in history. They dont need to make a new music video for each single or anything, either. | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2kgrn8/eli5_why_dont_artists_just_release_their_entire/ | {
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"A lot of artists produce songs which are meant to be listened together and in sequence as they enhance and compliment one another. If they were sold individually and listened to individually they would sound a lot worse because the artist would have failed to create an atmosphere needed to enjoy some of their works.\n\nSomething that goes along with this is, people tend to ignore a lot of songs released by artists because they're not considered hits, they may not necessarily be bad, but as mentioned above they don't stand well on their own. "
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3v13ed | what is the physiology behind being gay, lesbian, bisexual, transgender? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/3v13ed/eli5what_is_the_physiology_behind_being_gay/ | {
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"We're not really clear on it yet. There's some studies that suggest that transgendered people have brains that are physically closer to that of the sex they identify as, and some theories about hormone differences while in utero altering brain chemistry, but there's no real concrete answers yet."
]
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3zo2hg | what type of data is obtained from underground nuclear tests? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/3zo2hg/eli5_what_type_of_data_is_obtained_from/ | {
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"The main purpose of a test is find out whether the device can be safely armed and successfully detonated. The tests are performed underground for environmental and safety purposes, but can make taking precise measurements difficult. \n\n\nIf buried at an adequate depth, yields can be roughly estimated based on the size of the melt crater.\n\nOther data includes shockwave propagation rates, measured using pulse reflection. This has been used in the past to identify and correct early shell ablation, among other timing issues.\n\nToxic byproducts and radiation are also a point of interest. \n\nThe timings and magnitude of seismic and air waves, along with radiation, can be used to pinpoint the source of slow reactions and incomplete yields "
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f3j589 | what happens after you burst a blood vessel? does the vessel itself reform or do you have a gap there forever? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/f3j589/eli5_what_happens_after_you_burst_a_blood_vessel/ | {
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"It's called a bruise. The blood leaks out under your skin and makes a spill. The body patches up the vessel, or seals it off if it's too damaged. Then it cleans up the mess, that's why the bruise turns colors as the crashed blood cells get cleaned up, like after a highway crash. Then you are fine. Other nearby vessels expand and/or new ones grow to ge4t the traffic flow back to normal."
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5rd8i0 | how is youtube a sustainable business model? if view count remains constant but video storage costs continue to increase, wouldn't this lead to a permanent loss? | Let's assume that in 2020, YouTube maintains a daily view count of 500 million per day. However, they also keep old videos on the site that aren't generating views. Don't these "dead videos" eventually accumulate and overcome the profit margins with cost of storage? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/5rd8i0/eli5_how_is_youtube_a_sustainable_business_model/ | {
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"Storage costs are going down exponentially.\n\nEvery year the cost of storing 1 GB of data is half what it was the previous year.\n\nYouTube loses money every time someone uploads a long video that nobody watches, but it doesn't matter because they make insanely high profits off of the top 1% of the most popular videos.\n\nAs long as YouTube is a good place for popular videos, the business model is sustainable.\n\nIf it turned into an unpopular site where people just uploaded their personal videos but nothing popular or viral ever went there, it'd lose money.\n",
"As of the last time Google released any financial info about YouTube (early 2015) was that it was not a profitable business unit to operate.\n\nHowever, since then, most analysts are thinking Youtube is now profitable due to them selling way, way more ads than in previous years. Google has really taken a strong effort to get advertisers on Youtube, and the latest analysis thinks they will likely be profitable during 2017.\n\nHowever, in completeness, even if it was a money loser, Google would continue to operate it, as it provides benefits to google's other services. They (like many businesses) are willing to take losses in their left pocket to reap bigger profits in their right pocket",
"Eventually, maybe.\n\nThis can't be done eli5, can barely be done eliCollegeGraduate, but I'll try.\n\nThere are the fixed costs per video. Since Alphabet buys storage in such massive bulk they pay quite a bit less than you and I. They don't exactly like to tell people. So I'll use BackBlaze numbers and assume a reason profit margin to discount it. BackBlaze charges $0.005 per GB per month for storage, so I'll assume amortized over its lifetime we can assume for this Google is paying $0.003 per GB per month. Knowing their compression this is roughly an hour of stored video. \n\nImportantly the number is dropping. Costs per GB should roughly halve this year.\n\nYouTube of course has a lot of uploads, but YouTube is less than doubling each year. \n\nThe result is that in a year YouTube storage will actually cost less than today.\n\nThis is not permanently supportable, but should be sustained for 5+ years.\n\nComing soon we also have the shift in YouTube from VP9 to NetVC, this will reduce storage and bandwidth by as much as 25%. Making the storage cost even less. This will likely extend the storage cost reduction versus today to 8-9 years. After that they will probably have to purge some losing content, we probably won't even notice.\n\nThe bandwidth works much the same way. Alphabet buys so much bandwidth that they get it really cheap. They are paying less than $0.01 per GB streamed, I put their costs at roughly $0.003 per GB bandwidth.\n\nNow we have their costs what are their revenues? And how will they grow or shrink?\n\nToday YouTube ad rates come to $0.021 per viewed hour. 55% of this goes to content owners. This gives them $0.0095 per viewed hour to work with.\n\nYouTube stated they streamed 3250000000 hours per month in 2016, about $30 million a month after paying content owners.\n\nThe number of hours streamed likely won't increase by much, YouTube has reached saturation. However we can expect that ad pricing will keep up with inflation. At the same time we are seeing a rise in ad blockers with an expected growth of about 10% this year, but decreasing later. In 2019/2020 the growth of ad blockers will probably fall below inflation, meaning the revenue number will rise.\n\nSo what does this mean for YouTube revenue and YouTube profit?\n\n2016 YouTube probably turned a profit of roughly $130-150 million.\n\n2017 profits should be $120-130 million.\n\n2018 $110-120 million\n\n2019 $115-130 million\n\n2020 $120-150 million\n\nAt a certain point in the future if they do nothing it will flip upside down (2025ish) but minimal changes can keep it going to 2050 fairly easily.\n\nOf greater concern for me is the changes in pay to content owners. YouTube already pays among the lowest in the industry, and the next 2+ years will likely see the numbers drop even lower, after counting inflation it is possible that we will never see real pay per viewer hour rise on YouTube."
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3yon7h | does *absolutely everyone* on the sidelines of an nfl game have a reason to be there? | I understand there's a lot of people for checking on penalties and camera and audio stuff, but it seems like too many for just those. Looks like a lot of guys just standing around.. .. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/3yon7h/eli5_does_absolutely_everyone_on_the_sidelines_of/ | {
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"coaches (several), trainers, injured players in street cloths, water/towel boys, media (sound, cameras, on screen personality). police, cheer squad, security.\n \nIt seems the NFL does not have significantly more people than a popular H.S. game. \n\nSo I say essentially yes all the people have a reason.",
"No. Some people including some family members and celebrities are occasionally allowed on the sidelines. Most of the people there are necessary though. ",
"Most people serve a function, but teams can invite a few people to watch the game from the sidelines, it is considered a rare privilege.\n\n",
"Absolutely not.\n\nFor instance, sometimes family members are allowed on the sideline that don't have a job (i.e. aren't a ball boy or waterboy). Sometimes the owner of the team is on the sidelines and once the game starts the owner serves absolutely no function (the owner manages all of the off the field stuff so it serves no function to have them on the sideline). Similarly, a general manager might work their way down onto the field and they serve no purpose once the game has started. Sometimes teams will invite military personnel to join the team on the sideline as a show of support for the armed forces (they obviously don't serve a function in terms of the game). \n\nThat's four types of people that don't really have a reason to be there and could be in the stands without it having any impact on the game. Without that said, 99% of the people do have a reason to be there and removing them would affect the team, game, or NFL itself but it's definitely not 100%"
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69v43i | facebook scams. what do the accomplish by getting you to share a post? | ELI5: Caveat: I only started using Facebook on a regular basis about a year ago, and I use it primarily to steal memes.
I've seen a few varieties of these posts: "comment where you're from so I can see how far this has made it." "Please rate 1-10." And the ubiquitous "like, share, comment 'amen.'"
Is it just a vanity thing seeing notifications, or is there something more nefarious going on? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/69v43i/eli5_facebook_scams_what_do_the_accomplish_by/ | {
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"They are often designed to build up likes and followers then the owners of the page (usually located in a developing country not always though) will sell the page to scammers who can reach a giant audience (iPhone giveaways porn spam snake-oil weight loss solutions etc)"
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opcav | how do web browsers work? | . | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/opcav/eli5_how_do_web_browsers_work/ | {
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"When you request _URL_0_, the server sends back a bunch of textual data. Plain text is boring to look at, so a simple markup language was created named html. The browsers job is to parse through the html and display it nicely. Some browsers display things differently than others (that's why many people hate internet explorer).\n\nRequesting for a page can be very resource intensive on the browser (intensive in a very relative term). Most sites share similar layouts, so each request may be 95% of the same data (things like the header, footer). It doesn't make sense to request almost the same thing, so caching was invented. A browser stores commonly requested things locally on your computer. Caching improves the time for pages to load, since most of it is stored locally.\n\nOffline browsing uses the cache to save complete pages. If all the content is saved onto your computer, then you don't need a connection to view it. Thus, offline viewing. Offline viewing is only practical for pages which have content that never changes. If the page depends on any user submission, then obviously it won't work.\n\nA session is an exchange of information between the browser and the web application. They use 'cookies' to keep this information sorted. Cookies are nothing more than simple text files that your browser manages. Sessions and cookies are used alot in the internet, but for the average five year old, they keep you logged in for a specific time on a site. Cookies are the reason why you stay logged into Facebook on your computer. The cookie is stored only on your computer. \n\nAs for security, browsers don't do much. They can recognise certificates a site must have in order to be 'secure' (Called an SSL certificate). They can also recognize an invalid one too. They aren't smart enough to do much else though, that is left up to the user.\n\nI hope this helps!"
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cbml3f | municipal fiber internet. is it funded by the government or is funded by taxes? or do you just pay for it like you would for any other service (i.e. comcast, xfinity, etc...)? how does a town go about getting it (that is if they are in a state that doesn't ban it)? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/cbml3f/eli5_municipal_fiber_internet_is_it_funded_by_the/ | {
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"As the name suggests Municipal Fiber Internet is provided by the municipality (local government). The organization and funding of this is up to the municipality as is the same for any municipal utility like water, sewage and roads. It is not uncommon for the local taxes to pay for some of it however most strive for the utility to become fully self funded. Quite often the municipality only offers financial security to the endevour which is enough to get loans that will be paid back by the subscribers over the lifetime of the infrastructure."
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1s4hw5 | why do salt water and fresh water bodies stay seperate | Also what is it called | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1s4hw5/eli5_why_do_salt_water_and_fresh_water_bodies/ | {
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"Land for the most part. Lakes are fed by rainfall, and they occur most often in mountain valleys. Rain falls down the mountainsides making creeks and rivers that feed into the lake, and the water has no where else to go. When rivers feed into the ocean the fresh water mixes and eventually becomes salt water. This influx of fresh water is offset by evaporation, which becomes clouds, which rains to create the fresh water in the first place.",
"They *do* mix, just *slowly* due to density. Think of it as a crowded mall with people in red and blue shirts. Blue is water, red is salt. If the red and blue shirts are all mingled and walk in random directions but tend to stay clustered and a wave of blue shirted people walk into them there's a very thin slow level at which the red shirted people mingle with the new blue shirted people. Likewise it'll take a while for the red shirted people deep in the back of original blue shirted people to exit the mingled state to evenly disburse across all blue shirted people. \n\nYou might ask then, why is all fresh water not salt water? We then have to add motion to this case. Fresh water, in most instances where it meets salt is in a state of motion. Back to the original analogy, lets say at the mall we have a constant stream of blue shirted people pushing into the pack of red and blue shirted people. The rest a unlikely to penetrate deeply into the oncoming blue shirted people as new blue shirted people will always push them back into the pack."
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6fqv6a | how powerful does a nuclear warhead have to be to destroy our planet? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/6fqv6a/eli5_how_powerful_does_a_nuclear_warhead_have_to/ | {
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"What do you mean by destroy the planet. If you mean death star type explosion with no planet left you would need a bomb around 100 Zettatons of tnt which is around a quadrillion times as big as the most powerful bomb ever made.",
"You have to be more specific. It takes a lot more to disintegrate the planet into little chunks than to kill all humans within 100 years.",
"[This](_URL_1_) and [this](_URL_0_) give me a ballpark figure of:\n\n50 & #8239;000 & #8239;000 & #8239;000 & #8239;000 & #8239;000 & #8239;Mt\n\nCompare this to the biggest bomb yet detonated by man at:\n\n57 & #8239;Mt\n\nNote how one of these numbers is substantially larger than the other.",
"Planets are pretty big thing and pretty hard to destroy.\n\nEven if you somehow managed to shatter a planet to pieces the pieces would just be drawn back to each other to reform a planet unless you pushed the pieces very, very hard away from each other.\n\nThere is a theory that Earth was impacted by a very large and fast object very early in its development and that the impact was energetic enough to push out a massive amount of molten rock and debris that eventually formed our moon.\n\nThat was literally an earth shattering kaboom and the planet still was only changed but not destroyed in the process.\n\nWikipedia says that the largest nuclear explosion ever was when the Russian tested their Tsar bomb. It was theoretical a 100 megaton bomb but they tested it at 50 mt which works out to be about 2.1×10^17 J.\n\nWikipedia also gives the energy released by the asteroid that killed all the dinosaurs (except birds) as 5×10^23 J. This means that impact was about 2 million times stronger than the strongest atomic bomb and while it certainly ruined the day for everyone a round at the time it didn't destroy the earth or kill all our ancestors (little furry things that they were).\n\nWikipedia also gives a value for the gravitational binding energy of Earth (which I assume would be needed to overcome to blast the planet apart) as 2×10^32 J. This would be 10^15 (a quadrillion) times higher than the largest nuclear explosion ever.\n\nYou can't really imagine a quadrillion times of anything with a human brain, but it is a lot. We can't scale up nuclear bombs that big.\n\nSo the Earth is safe from being blown apart by man made nuclear explosion.\n\nThat is good.\n\nAs the above value for the dinosaur killing impact shows we are probably also safe from completely destroying our own ecosphere on top of the planet. It is much more fragile than the planet itself, but it has survived explosions a million times bigger than anything we ever made and came out fine eventually.\n\nSo we won't kill the planet or life on earth.\n\nHumanity is even more fragile than life on earth. The giant impact above killed of all land species bigger than a medium sized dog. That sort of thing would have a good chance of killing of humanity.\n\nEven more fragile is human civilization. You don't need to kill of all humans with the explosion just make it big enough that the survivors will be bombed back into a stone age. That would be still too much for s ingle full yield tsar bomb, but the nuclear powers of the world have enough bombs to be able to confidently cause a collapse of human civilization, with a small but non-zero chance of total human extinction.\n\nThe earth will be fine. We won't."
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bzict9 | why are eggs almost universally sold in packs of 12? what made farmers agree to sell this way? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/bzict9/eli5_why_are_eggs_almost_universally_sold_in/ | {
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"TLDR; Convenience, 1 shilling = 12 pennies, 1 egg = 1 penny. No need to make change.\n\nUnder a system that came to be known as English units, which was a combination of old Anglo-Saxon and Roman systems of measurement, eggs were sold by the dozen. It made sense to sell them that way because one egg could be sold for a penny or 12 for a shilling, which was equal to 12 pennies. That system held sway in the American colonies and persisted after the revolution, becoming part of the system known as U.S. customary units. Such units are used for consumer products and in industrial manufacturing.\n\nThe British have moved on, adopting a wholly new system of weights and measurements in 1824. But they still mostly sell eggs by the dozen.\n\nThus, in the United States, a vast majority of eggs are sold by the dozen, half-dozen and other multiples of 12. But in India and parts of Africa, it isn’t unusual to buy eggs by the piece, and in some countries they may be sold by 10s or 8s. ",
"12 is a really convenient quantity to sell items in, especially when you'll likely be dividing that 12 into smaller numbers (e.g. a 3-egg omelet.) This is because 12 is divisible by 1, 2, 3, 4, 6, and itself, which is unique for how small of a number it is.\n\nIn fact, there are even people who think we should transition to a base-12 numbering system for this reason.",
"What else would they do with that extra space in the cardboard egg containers?"
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3engh7 | how does "lottery wheeling" work? | I've read that it's a strategy used by lottery players to increase their odds of winning, but the Wikipedia article is confusingly saturated with information and I would love to have an ELI5 explanation that summarizes it well. Thank you in advance. | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/3engh7/eli5_how_does_lottery_wheeling_work/ | {
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"The only part of the Wikipedia article you need to pay attention to says that wheeling does not change the expectation value of the ticket. That means that the probability of paying more for the ticket than you win is still nearly 100% and the more you play, the more you are expected to lose."
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5xq3yp | the difference between public and private sector labor unions | [deleted] | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/5xq3yp/eli5_the_difference_between_public_and_private/ | {
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"A public sector labor union is a union comprised of government workers. A private sector labor union is a union comprised of private employees.\n\nThe biggest difference is that public sector labor unions largely negotiate with other government employees or politicians for their contracts. Private sector employees negotiate with the company's counsel.\n\nPrivate sector unions negotiate for a larger share of the profits they help create. Public sector unions negotiate for more tax funds. It is for this reason that even FDR (extremely liberal president) was highly against the idea of public sector unions."
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6mbv6o | given how hard it is to start and run a successful small business nowadays, how were so many immigrants able to come here with nothing, and and still start up businesses in the cities where they settled? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/6mbv6o/eli5_given_how_hard_it_is_to_start_and_run_a/ | {
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"In the old days there were extremely few regulations, and they were not well enforced. If you wanted (for example) to buy some stuff and sell it retail from a wagon on the street, you could just start doing that.",
"Clarification: I refer to immigrants of the WW1-WW2 era, give or take, maybe a skosh earlier.",
"There wasn't as much competition like there is today. Also take an Italian immigrant for example. They create an Italian restaurant therefore other Italian immigrants in the area would dine there. Back then ethnicities were a lot more segregated, and so that would help the business. \n\nI also feel as though back then there was more of a sense of community and everyone shopped and ate locally. Now everything is a chain. ",
"Competition and market saturation. \n\nNow everyone has to compete with mega stores, chains, and established stores in every town and the internet.",
"1 in 10 businesses succeed which isn't terrible - I'm guessing the odds are a lot better on your second try as well.\n\nRemember those immigrants had a lot of determination as they often couldn't find good employment. Not to mention they had cheap labour from their family. \n\nThe result was that immigrant businesses could run just barely making enough money to feed the family and push through to a more profitable state.",
"70% lack of competition, 20% lack of regulation, 10% racism.\n\nI'm not sure if you are aware but anything legal or illegal you want is a phone call, text, email, or web page away. Hot mexican food. Hot mexican music. Hot mexican drugs. Hot mexican women. Or asian or canadian or italin or whatever flavor of food or entertainment or sin you want.\n\nIt's *HARD* to compete with a multi-national organization dedicated to delivering the most pleasurable product at the lowest cost, be that Taco-Bell or a drug cartel. They can get their product so much cheaper than you can and they can pay their employees starvation wages and just hire a new guy when the current guy wears out. You can't do that so why would they buy from you?\n\nRegulations are a lot stricter these days. You need liscences and training and if you have a criminal conviction or no money it means you don't get to sell food out of a food truck. In previous eras you just put up a wooden stall on a street corner and started selling food and no one bothered you, even if some of your customers got sick.\n\nRacism. Or, to put it more politely, races 'stuck together'. It was considered normal to only patronize restaurants run by your race. So an asian with a lot of money could open up an italin restaurant, but the italiens wouldn't' come and eat there because what's this slanty-eyes doing in little italy? You came to America and you moved to little italy and you got a loan or a job and that's what you did. You still see this to some degree in the Mafia, Hollywood with jews."
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2p5k2q | why do doctors flick syringes before injecting someone? is this just a thing they do in tv shows? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2p5k2q/eli5_why_do_doctors_flick_syringes_before/ | {
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"They are checking for air bubbles. Injecting a air bubble into a blood vessel can easily kill a person.",
"Its to remove any possible air bubbles. They don't just flick it, they take a little extra solution and shoot that out.\nAir bubbles can cause an embolism",
"They flick the syringe while holding it inverted to agitate any air bubbles then they depress the plunger to evacuate those air bubbles"
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93qco5 | the difference between single phase and three phase power | I hear these terms thrown around a lot and just not sure what the difference is. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/93qco5/eli5_the_difference_between_single_phase_and/ | {
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"Both are forms of alternating current (AC)\n\nAlternating current cycles from +120V to -120V, 60 times per second (assuming you live somewhere that uses 120V 60 Hz for mains power)\n\nSingle phase power means that all of the power in the wire alternates from +120V to -120V. \n\nThree phase power has three wires, all alternating from +120 to -120, all at the same frequency, but they are offset from each other. Basically, when Phase 1 is at its peak, Phase 2 is in the middle, and Phase 3 is at the bottom. So in 3 phase, there's virtually always a wire at 120V or very close to it. It delivers a steady stream of power, and that makes it much more useful for higher electrical loads.",
"Imagine you are holding a pole, and someone else has the other end. The other guy pushes you with the pole, then pulls, then pushes, then pulls, etc. etc. Really fast. You never go anywhere, but you get pushed back and forth. That's single phase power. \n \nNow imagine that there are 3 poles, attached to your belt at 120 degree spacing. Pole A pushes you, and then when they are pulling on you Pole B pushes you, and when Pole B is pulling on you Pole C pushes you. All of them push and pull you constantly, but out of synch. You never go anywhere, but you get pushed/pulled a lot. This is 3 phase power. ",
"It is basically 3 lines of same voltage that are 1/3 out of phase with each other. AC is push/pull on the electrons created by (in traditional rotary style generators) magnets moving past a coil. The + side of magnets pulls the electrons, then the - side comes in a pushes the electrons, and this goes back and forth creating an alternating current in the form of sin wave. Now, within this generator the coils/magnets are arranged in such a way that as one coil's electrons are pushed another's is pulled and yet another is right in the middle, each of which is it's own phase. These 3 lines leave the powerhouse at super high voltages, 500KV+ and are distributed to the \"grid\". They run to sub stations that take in these high voltages and convert them down to say 10KV. These mid level lines are then distributed to points of use where there is another transformer that converts it down to 110V. Now, most homes and small businesses only need 1 phase, so the transformer for that location only pulls off of 1 of the 3 lines. Converts it to 110V and sends it into the building. However, big industry that uses big electrical motors and such will actually have all 3 phases come in and those 3 phases are fed to the motor. A 3 phase motor is much more efficient, creates less heat and can generate more power. ",
"From someone who has worked 30 plus years in industrial environments. Surprised that everyone in this thread is stating 120 volt 3 phase as if that's even a thing. Most 3 phase power in the U.S. is 480 VAC 3 phase. That's what most industry uses for powering moterized equipment. 240 volt 3 phase is also used but less common. I have never heard of 120 volt 3 phase.",
"If you are really 5 years old: \n\n* Imagine three people on a row boat. \n* Single-phase power: One guy is rowing, and each stroke takes three seconds. Stroke - 2 - 3. Stroke - 2 - 3. It's enough to move the boat. It's enough to power virtually any modern equipment -- whose power supply takes those strokes and converts it into useful energy.\n* Three-phase power: All three guys are rowing. Each person's stroke takes three seconds. But they each stroke exactly 1/3 after the last dude goes. So essentially, you are never more than a third of a stroke off the some guy's strongest.\n\nThis explanation is not a literally 100% precise analogy, but it's reasonably good enough. One complication is that:\n\n(a) in the United States, where 3-phase power is commonly \"line-to-line\", the power of a 3-phase system (at a certain amperage) is not literally 3x the power of a single-phase system (at the same amperage). For reasons beyond the understanding of a 5-year-old, it is 1.732 times greater.\n\n(b) in Europe, where 3-phase power is commonly \"line-to-neutral\", it's a better analogy.\n\nBut whatever, you are five."
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6ihtn3 | can smelling something be unhealthy? like if there's a very bad smell, is there anything dangerous about the act of smelling it? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/6ihtn3/eli5_can_smelling_something_be_unhealthy_like_if/ | {
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"Unless the fumes contain chemicals that in their vapor form can damage breathing or affect the brain, no. Bad smells are not inherently more unhealthy than good smells. But if you're sniffing gasoline, which has a dangerous vapor form, then yeah, you'll get sick. ",
"Yes. Stuff like paint- and glue fumes can be highly toxic.\n\nI don't think that \"regular\" bad smells like rotting fish or excrement are dangerous even in large quantities, but both foster a myriad of harmful microbes so the smell is evolution telling you to stay away."
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8fpzn3 | does a house ever finish settling? | Sometimes a building will just creak and it's always been explained that the house is just settling. I take it to mean that the house is just slightly moving. Is this repositioning ever complete? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/8fpzn3/eli5_does_a_house_ever_finish_settling/ | {
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"Short answer: no\n\nLong answer: I believe it is never settled because it's the materials of the house expanding due to the heat of the day and then contracting when it's cooling down at night"
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8bybpq | in the shell sort algorithm, why are the numbers 1,4,10,23,57,132,301,701,1750 used? they seem to be ambiguous and are really confusing me... | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/8bybpq/eli5_in_the_shell_sort_algorithm_why_are_the/ | {
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"Shell sort partitions the data. The exact partition is not that important, but the properties of the partition (i.e. \"gap sequence\") do affect the runtime.\n\n\"Gonnet and Baeza-Yates observed that Shellsort makes the fewest comparisons on average when the ratios of successive gaps are roughly equal to 2.2.\"\n\nYou need to have some numbers to do the partition, so those numbers are one set that is known to work well, but you can change them and it will still work.\n\n_URL_0_"
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3418ss | why does scanning take so long if photocopying or taking a photo of something is so quick? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/3418ss/eli5_why_does_scanning_take_so_long_if/ | {
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"Because you have a cheap scanner. Cheap scanners are slow. Expensive high end scanners are very fast.\n",
"Most photocopiers are optimized to scan very quickly, and do so at a very low resolution. 100x200dpi is not an uncommon setting. If you're scanning a photograph, the 300x300 setting is much more common, with 1200x1200 requiring a bathroom break. Most wall powered scanners (i.e. not getting their power directly off a USB port) can approach the scan speeds of a copier if they're set to a very low, black-and-white resolution. Also, many USB-only scanners have weak servo motors that control the scanning lamp due to the limited amount of power available through the cable. Scanners that plug into an electrical outlet have more power available to them and can put more torque on the lamp.",
"When you take a picture of a page, the light from various parts of the page enters at different angles. Ultimately the causes some lens distortion. The photo of the page isn't a perfect rectangle; the page bows out on the sides.\n\nA scanner takes a different approach. It has a photoreceptor that isn't concentrated in one spot, but is distributed across a bar. This whole ensemble is moved across the page. So there is no lens distortion: the page is scanned \"orthogonally\" (at a perfect right angle at every point), so there is no issue with perspective. This gives you a perfect rectangular image, as you expect.\n\nNow, it's possible to correct lens distortion and take an instant snapshot of a page with a camera, winding up with a rectangular image. But this requires precise positioning of the camera, which makes the whole ensemble larger than a scanner. Most people don't want a big bulky scanner, so waiting a few more seconds is a good tradeoff. Some places, like libraries, may indeed have \"photo\" style scanners which are bulky but faster.\n\nAside from avoiding the lens distortion, scanners also apply light evenly to the image. Again, possible with a camera, but requires a precisely tuned (and large) ensemble.\n\nScanners use a slow, but cheap, compact, and reliable method to get a great, high-resolution scanned image. You can make tradeoffs for speed, but generally scanners are the best approach for casual users.\n\nEdit: I didn't address photocopiers. Obviously, these are also larger than scanners. But the main issue is they tend to have lower resolution and worse contrast due to the methods they use for lighting the image. They are designed for final-step reproduction that's \"good enough\" in most cases. You might want the better results from a scanner for archiving documents, plus scanners are smaller and cheaper. Essentially they're better in every way but speed, which is fine for people who occasionally scan documents.",
"Compare a pro-level photocopier with a pro-level scanner. The Canon DR-7580 scans 75pages per minute -- *both sides at once*. Your $50 HP from OfficeMax is a poor comparison."
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89ect0 | why do heroin users have to switch veins? what does the heroin do to “kill” the vein? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/89ect0/eli5_why_do_heroin_users_have_to_switch_veins/ | {
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"It's not the heroin. It's poking the same spot with a needle over and over again without giving it enough time to heal. It can get more complicated where if you *do* give it time to heal after you've abused it too much it will develop scar tissue which makes it harder to inject there. ",
"I suspect it's less about the heroin and more about the needle but I don't know for certain.\n\nFirst of all, needles are meant to be single use, but they can be hard to get so addicts often reuse and share needles (which is also why they have a very high HIV and other blood borne pathogen risk). The needle is bent, cracked, and blunted with each use, making it more destructive to the vein, both physically by making a more ragged hole, and by introducing pathogens and causing infection.\n\nEven if they did use a fresh needle every time though, every stick is at least a little traumatic to the vein wall. Chemo patients, patients on dialysis, and other chronically ill patients that require frequent venipuncture often have scarring on their veins as well (it feels like sticking rice crispies) and that's if the vein doesn't collapse altogether. Also if they're sticking themselves one handed it will be a less accurate shot, since using your other hand to stabilize the vein makes for a much smoother stick.\n\nThese are my thoughts as a former phlebotomist, not knowing much about heroin, but knowing a lot about venipuncture."
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98x0om | how are things n% water? | How is the human body like 70%/80% IIRC water? How is a cucumber like 95% water? I can understand with liquids or wet things but how is the water content of a banana or piece of muscle or bone calculated? How do water molecules just seem to be incorporated into everything? Why water? What purpose does it serve? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/98x0om/eli5_how_are_things_n_water/ | {
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"text": [
"Heat it until the water evaporates, check its mass before and after and calculate the percentage"
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bx3tsu | how usa is one of top polluters in most sources but is consistently ranked relatively favorably (in the middle) for how polluted it is? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/bx3tsu/eli5_how_usa_is_one_of_top_polluters_in_most/ | {
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"A lot of it is just how big the US is and how much the population and industrial centers are spread out.\n\nIf I have a country that is 100 square miles and pollutes x amount, and a country that is 1000 square miles and pollutes 5x amount, the second country pollutes 5 times as much as the first country but said pollution is spread out over 10 times the area, so would likely be only half as polluted.\n\nOversimplified but still pretty accurate. The USA is the third largest country by area behind Russia and Canada and ahead of china.",
"Because there are lots of efforts to keep our land clean. We also have a first class trash disposal service, cities that pay a lot to stay clean, laws regarding waste disposal, ect. National pride helps, motivated people to preserve our natural beauty. Some big cities are very polluted but are making efforts to clean up. \n\nThe United States is massive and full of green forests and clean water. The forests help keep our air clean. It's also full of national parks, nature reserves, and federal land that is not allowed to be developed and kept in a clean natural state. A huge portion is of my state is government land that is not allowed to be developed. They wont even allow cell towers to be built. Being huge and so spread out helps. Also having the Pacific Ocean to shield us from Chinas pollution helps.\n\nI grew up in a very clean midwestern farming state. Amazing crisp clean air and clean water. Can literally drink right out of the lakes. Had no idea what pollution really looked like until I lived in Korea for a year. \n\nMuch of US pollution is air pollution from industry and high ownership of person vehicles. But since the 70s most other forms of pollution have been attacked and limited. So less industrial waste in rivers and trash on the ground than other nations. I think the US is also blamed a lot for the trash that ends up in the sea but I could be mistaken. The US makes incredible efforts to preserve our natural beauty.",
"Because the US isn't \"polluted,\" even though it emits a rather large amount of pollution.\n\nOutside of a few individual cities (particularly LA), smog, particulates, NOx, and SOx emissions are relatively low. The US really just produces two emissions; carbon dioxide, and methane. One is only harmful at concentrations above 1000 PPM for sustained periods (which we're not really close to in the ambient), and the other is completely odorless, colorless, and benign to living tissue.\n\nThe other important aspect is that the areas where pollution density is highest (our cities) are still significantly less polluted than our peers overseas, entirely because our cities are so much less dense. Emissions follow consumption on a per-capita basis, and so when you have a lot of people crammed together, you're going to have a lot of emission production crammed together as well. The US really only has three cities that have population densities approaching our peers in Europe and Asia; two of them (NYC and Boston) are kept relatively clean via city regulation, and the third (Washington DC) is kept clean by virtue of the US government bending over backwards to keep the Capital looking spotless (helped in major part by the fact that the National Mall is National Park space).",
"The reason the USA is one of the top polluters is because there is a lot of American compare to other country and it's an industrialised country. But at the same time the US is a big country with population spread over large area. In 2017 here is CO2 emissions stats for the US and their ranking.\n\n10,877.218 metric tonnes of CO2/year. The US is ranked as the second biggest emitter.\n\n519 metric tonnes of CO2/km²/year. The US is ranked 66th.\n\n15.7 metric tonnes of CO2/capita/year. The US is ranked 16th.\n\n & #x200B;\n\nIn addition, now all pollution are the same. If you are talking about air pollution, CO2 have little effect on that, it's air particle that will make the quality of the air drop. It's also a very regional problem, and vary a lot over time. If you look at the Air Quality Index map here: [_URL_0_](_URL_0_) \n\n & #x200B;\n\nYou can see that the problem is the worst in India and China where the regulation are more limited and that even over the US it can range from unhealthy to good on the same country. Geography is another huge factor. City that are in open plains will have cleaner air even if they pollute a lot, but a mountain chain near a city can stop the air over it from spreading the pollution.",
"It depends on what you mean by \"pollution\". The US is one of the leading emitters of carbon dioxide, which causes global warming and climate change. However, thanks to fairly good regulation by the Environmental Protection Agency, the US is pretty good in terms of sooty particles, acid rain, ground-level ozone, photochemical smog, and chlorofluorocarbons -- and it's *much* better than it was a few decades ago. Water and soil pollution are also fairly well controlled compared to other countries, and compared to our past.\n\nEnvironmental regulation works, but when we call it all \"pollution\" we hide the fact that some things aren't regulated."
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7st35i | the waco siege. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/7st35i/eli5_the_waco_siege/ | {
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"a ups driver was delivering packages to the compound and one broke open showing weapons, inert grenades and black powder. UPS reported this to the sheriff who contacted the ATF. This info along with reports of automatic fire from the compound led to sucspision that the Brach Davidians were illegally modifying weapons to be fully automatic. The ATF got a search warrant and prepared a raid. The Davidians knew the raid was coming. During the raid shots were fired but it is still debated who shot first. During the ensuing firefight, 4 ATF agents were killed 16 wounded and 5 Davidians killed, but the compound was not successfully breached which led to the siege and the FBI taking over. Eventually the FBI tried to gas them out using tear gas, during this fire broke out in the compound which spread rapidly. 76 Davidians were killed in the fire and 9 escaped ",
"The ATF suspected the Davidians of hoarding illegal weapons and moved to seize them. After a gunfight that left 4 agents and 6 cult members dead, the ATF and FBI began a siege of the compound that lasted 51 days. After that, the FBI raided the compound again, which led to the infamous fire that killed 60-70 people.\n\nThe FBI wanted the final raid essentially because they wanted the entire thing to be over, but also didn't want to back down which they feared would embolden other far-right groups (remember that the Waco Siege occurred right after the Ruby Ridge episode, where the government utilized controversial and severe rules of engagement). Instead, they got a massive controversy that scared a lot of people, and which was later used as a justification for the bombing of the Oklahoma City Federal Building.\n\nThat being said, the Waco Siege also became a favorite topic of conspiracy buffs who want the government to be the root of all evil in these kinds of situations, and who also tend to gloss over the fact that the Davidians likely started the fire themselves.",
"\nThe Branch Davidians were a reclusive religious cult and had all the signs typically of being dangerous and abusive. This was only about 15 years after Jim Jones and the Guyana mass poisoning, so dangerous brainwashing cults were still kind of fresh in the public consciousness. Charismatic leader, little or no contact with family members, people weren't free to leave, sexual abuse, etc. Due to a damaged package, the Bureau of Alcohol, Tobacco and Firearms (ATF) believed they were illegally making automatic weapons, and had enough evidence to convince a judge to issue a search warrant. \n\nFearing an armed response, they showed up in force prepared for a raid. While the ATF is a full-fledged law enforcement agency with gun carrying officers, their mission is more regulatory in nature. Instead of asking a more enforcement-oriented agency like the FBI for assistance, they decided to handle it themselves and many feel their inexperience contributed to the disaster. In particular, the Davidians were tipped off that the ATF was coming and were prepared, and a show of force may have escalated the situation. \n\nThe Davidians refused to comply with the warrant. Their compound was fortified, heavily armed and had members patrolling the walls, leading to a tense armed standoff. A firefight erupted (it is still not clear who shot first) and a handful of people on each side were killed, but the Davidians still held their compound and a siege ensued.\n\nAfter couple months, the FBI had taken over, and tried to drive the cultist out with tear gas. A fire erupted and dozens died, including many children. The survivors claimed the fire was started by the FBI, either deliberately, or accidentally with tear gas canisters or by knocking over lanterns (their electricity had been shut off). However, a panel of arson investigators found that the fire had been started at three separate locations at the same time, making an accident very unlikely.\n\nFar-right groups were very critical of the operation claiming it was government overreach to suppress gun rights. It occurred just a few months after the Ruby Ridge siege, where the FBI wound up shooting and killing an infant in a standoff with a white supremacist militia leader, making it appear as part of a pattern of government abuse. Also, it was in the first few months of the Clinton administration. Janet Reno, the unphotogenic first female Attorney General was ultimately in charge, and many people questioned her competence, and whether Clinton appointed her for diversity rather than ability. The issue dogged them both throughout the administration, and various conspiracy theories about the FBI firebombing the compound and using cyanide gas emerged.",
"Check out the doc The Rules Of Engagement for a different, but sobering take on how bumbling our govt can be.\n\nWondering if they'll ever do a docudrama on the Ruby Ridge incident and how badly the govt f-ed that up that they ended up paying out on a 3.1 mil lawsuit "
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3mhzyy | what is the evolutionary benefit to a species, such as the praying mantis, to have the female kill the male after copulation? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/3mhzyy/eli5_what_is_the_evolutionary_benefit_to_a/ | {
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"By eating the male, the female gains a lot of nutrients, which will enable her to have healthier and stronger offspring. In this way, there is a higher chance that the genes of both the male and the female are carried on.",
"To top off what palcatraz has mentioned, evolution isn't about what is best for the individual (the male mantis) or species, but for the reproduction and propagation of genes. By sacrificing their \"container\", the body, the genes of the male mantis increases its chance of being successfully propagated, so such sacrificial/cannibalistic behaviour becomes a favoured strategy.",
"To piggy back off of this, does the male know that he is going to get eaten or not?",
"Eating the male is not required for mantises to reproduce. Only about a quarter of mantis relationships end in cannibalism. The female mantis will eat the male if she is hungry. It is easier to just eat the male than it is to go find prey to eat.\n\nCannibalism is common in insects. Many insects kill and eat other insects, often in their own species. Cannibalism is not a problem for insects because there are so many insects. When an single female insect lays eggs, she can lay hundreds, of eggs. Because of the numbers of insects that exist, if a few insects get cannibalized it makes a small impact on the population as a whole.\n\nInteresting side note about Mantises and cannibalism. When a mantis lays eggs, they lay them in an egg mass called an ootheca. Sometimes the mantises that hatch early will stay around the ootheca and eat their newly hatched siblings, literally spawn-camping their family members. \n\nSource: I took an entomology class this on time.\n"
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417fmz | if someone is on death row and has a medical issue causing them the die sooner than their execution date, why would they be given medical help? | Morally I kind of understand, but financially and logically it does not make sense to me. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/417fmz/eli5_if_someone_is_on_death_row_and_has_a_medical/ | {
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"Up until the moment the executioner turns the key, the state must provide care for their convicted felons. The logic behind this is that up until that last moment, the execution is not 100% certain. There are years of appeals, and the governor might still pardon the convicted at the last moment. Also, allowing someone to die from a disease without treatment can be considered as cruel and unusual punishment.",
"* there is always the possibility the execution will be postponed, for any number of reasons\n* executions are supposed to be humane, dying of a treatable medical ailment may not be\n* it could create a perverse incentive for the state to withhold or botch medical treatment\n* they were sentenced to death by execution, that's not something you want to play \"close enough\" with\n\n\n\n",
"Because we're not animals who think it's okay to let someone suffer no matter what it is they've done. Sure they may have \"deserved\" the suffering, but it just isn't the right thing to do. He/she was the criminal, not us.",
"People who are in need of medical assistance are required to be helped unless they have a DNR (Do Not Resuscitate). Just because someone is set to be executed on a certain day doesn't mean they can just be left to die before the date. That would mean the person in question was lied to about when they're being put to death since, legally speaking, refusal to help someone you're capable of helping is participating in their death.",
"The short short version is that the government can legally mandate an execution and when that execution occurs, no individual is at fault for killing a person. \n\nIf someone like a prison guard or a doctor chose to withhold care and let the person die, that is effectively vigilante justice, which is illegal. "
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3ueemv | it's common knowledge that exercising regularly and pushing yourself is good for your health and heart, but how does that logic work that the harder you work your heart, the healthier it becomes, instead of wearing it out? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/3ueemv/eli5_its_common_knowledge_that_exercising/ | {
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"The human body is a fascinating thing. It has been developed to be able to adapt to different lifestyles. When working out, you are essentially telling your body that for your lifestyle, you require stronger muscles. The body has learned to oblige to this, thus makes muscles stronger by adding more protein to the muscle cells (contrary to popular belief, the muscles do not gain more cells, the cells get more muscle protein, and become bigger in the process).\n\nIf strong muscles are no longer needed for your lifestyle, the body will adapt to that as well, making you lose muscle."
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2r7e95 | why is it that when my battery dies on my iphone it takes 10 minutes to turn back on while connected to a charger? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2r7e95/eli5why_is_it_that_when_my_battery_dies_on_my/ | {
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"Apple makes sure that the phone is charged to a minimum % (3%-5%?) before it turns on, to make sure it doesn't die again when you unplug it."
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6g4uhs | why does ukip have so many meps as opposed to other government positions? | They have 20 MEPs but only 3 members of the House of Lords or House of Commons. How does that happen? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/6g4uhs/eli5_why_does_ukip_have_so_many_meps_as_opposed/ | {
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"UKIP supporters really, really, *really* hate the EU.\n\nMost everyone else just doesn't care about MEPs.\n\nSo UKIP voters are more energized in European elections than the general public.",
"The First Past The Post system also does them no favours in the House of Commons. In 2015 they got plenty of votes, but you don't get anything for coming second in a constituency. Under a proportional system, they'd have had 80 or so MPs.\n\nHaving said that, they still got a significantly larger share of the vote in the 2014 European election than in the 2015 national election."
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92yvvv | - why is, what seems like rape so prevalent in the animal kingdom? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/92yvvv/eli5_why_is_what_seems_like_rape_so_prevalent_in/ | {
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"Because most animals don't have morals. Humanity has gotten to a point of intelligence and society that we don't need to allow ourselves to just procreate willy-nilly. \n\nCats, dogs, and other animals rape as part of procreation because they don't have the morals, the intelligence, the sense of caring for others, that says \"maybe they don't want sex\".",
"Why not? If you're a male animal, and your primary goal is to increase the chances of your genes passing down as much as possible, you'd have sex with anything you can unless there's something preventing you.\n\nThere's no police in the wild, the only thing to really stop you is social factors, if you live in a complex enough social structure for that to matter. ",
"Animals don't 'rape' each other they don't have the capacity to even process that type of instinct for the most part",
"The most important thing to note here is that animals are amoral. There is no such thing as murder between animals; simply killing and being killed. Likewise, there is no concept of \"consent\". In most species, sex is not for pleasure but purely for reproduction. \n\nThe reason it is so common to see male animals \"forcing\" themselves on females to mate is because females are the choosy sex. Eggs are far more biologically expensive to produce than sperm, and therefore in higher demand. Much of sexual selection is female choice. Any male that manages to successfully reproduce and pass on its genes is \"fit\" (as in survival of the fittest), and often this involves being physically strong enough to overpower a reluctant female. Other times, it involves enticing a female. There is such a huge range of mating behaviors and systems that it is difficult to generalize, but that's about the gist of it. \n\nOne more factor here is that as far as we know there is no emotional component to most animal reproduction. It's just, \"will you make babies that will live? Alright, let's mate.\" It is purely an instinctive and physical process. Calling it rape implies that the female is traumatized and that the male has committed a wrong when this is simply not true.\n\nEdit: One more thing. In many cases sex is painful for the female, which we tend to anthropomorphize as rape. However, painful intercourse incentives the female to be selective in her mates. Evolution is basically just a competition to see who can reproduce the most successfully. Reproductive success is generally interpreted as the relative number of offspring that also reproduce. If the males adapt to their role of either enticing or subduing a female, and the females to theirs of selecting the most fit mates, things seem to work out.\n\nSource: senior bio undergrad focusing on zoology. I know way too much about animal sex.\n\n"
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3rd7sv | why don't vending machines keep their change topped up from the money people put in? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/3rd7sv/eli5_why_dont_vending_machines_keep_their_change/ | {
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"Filtering a coin box and setting it up so that it can provide change is possible, but requires a more expensive model of vending machine. Most vendors are willing to pay for a cheaper model because guess what, people are still going to use it.",
"That would be a convenience for you. But to the vendor it would be an extra cost. They vendor also has to make trips to stock the machine. Their preference is to also stock the change mechanism the way it is now and to not bother with refilling it with coins supplied by customers.",
"Your machine is broken.\n\n[This Coinco machine](_URL_0_ ) is the standard in the US, and it sorts input coins for future change and only dumps them in the bucket if it's full. You can still see the \"correct change only\" light when there is less than a dollar in the acceptor or only quarters if the price requires dimes and nickels to make change from a dollar.",
"They totally do, but a lot more people put in bills than coins. The total inflow of coins is rarely enough to fulfill the need for change. \n\nSource: I worked as a vending machine serviceman for 4 years. ",
"In a lot of vending machines what handles change is a device called a coin mechanism. This device auto fills when change is added but requires a certain threshold to be passed before it will allow for bills to be used. So if you see somebody put in 2 dimes 2 nickels and 2 quarters it isn't to a point with which it can realistically afford to stop taking exact change. Also the coin mechanisms go bad semi frequently and will stop accepting new change because they are broken. As a vendor this is preferred to the counter point of the coin mech jackpotting which means instead of giving you back 10 cents worth of change it will discharge the entire contents of the coin mech (~$20 if full).",
"Our workplace just put in a new type of vending machines. Doesn't make change, has to be exact change, but you can use your debit card if you want. Turns out that if you use your debit though, you're gonna get hit with some fees. Adds up to be about half-again what the product was.\n\nAnd they wonder why no one is buying anymore....",
"Probably because the designers believed that by the time the change ran out, the machine would have to be refilled again anyway.\n\nReally it wouldn't be an issue if the change holder were big enough for that to be true."
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9cje19 | why do egg-whites foam when we whisk them and do not when there is just a very tiny amount of egg yolk in it? | Why do egg-whites foam when we whisk them?
I notice when there is just a drop of egg-yolk in the egg-white bowl then no matter how long or how hard we whisk the egg-white will never foam. What does the egg-yolk do? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/9cje19/eli5_why_do_eggwhites_foam_when_we_whisk_them_and/ | {
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"The foam form the whites is formed by proteins from the protein-rich egg-white. The yolk contains fats that destroy the protein foam (also called an emulsion). You can try this by mixing in a tiny amount of cooking oil into the egg-whites: it will have the same lack-of-foam effect as a tiny amount of yolk.",
"Whipping egg whites is kinda like building a sand castle. In this case your \"sand\" is little air bubbles and the \"water\" you need to make it stand up is the egg whites. A little bit of oil in your \"cement\" makes it not so sticky and the whole structure falls over.",
"Actually eggs will foam when whipped with yolk present, they just take longer to foam and the foam is not quite the same texture, little less stable. My favourite chocolate cake requires 4 whole eggs beaten till peaks form. ",
"Related question - why does using a copper bowl or whisk ake such a difference?",
"To compound what was already said by others, you actually can foam egg yolks. It's more difficult than with the whites, because yolks contain far more fats and far less water than the whites but it is still doable in the right conditions: the italian *zabaglione* cream is exactly that. The trick there is to mix yolks, sugar and a liqueur like *marsala* or *vin santo*, then gently heat the mix while vigorously stirring... the heat will make the ethanol inside the mix boil, forming steam bubbles that will make the foam grow (air is insufficient) and more importantly it will make the proteins in the yolk coagulate, stabilizing the foam. It is difficult to make the right way because you need to heat the mix slowly and exactly at 83°C and keep it at that temperature for a short time, long enough to make the right % of proteins coagulate but not for too long (or the cream will become too firm and unpleasant). Some chefs quickly cool the cream with ice after it reaches the desired firmness to stop the reaction exactly at the right point. Others will serve it still warm.",
"BTW if you heat your whites a bit it is easier to make an emulsion and it's more uh... solid"
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3vk6hr | how do we not run out of telephone numbers? | I understand that they recycle telephone numbers from previously subscribed customers, but a standard 10 digit number could only have 3,628,800 combinations right? How have we not reached the quota? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/3vk6hr/eli5_how_do_we_not_run_out_of_telephone_numbers/ | {
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"10 000 000 000! There are ten billion possible numbers you can create with 10 digits plus all the recycled ones and youre done. Its true however that we are soon to be running out of them and companies are already looking for a solution.",
"How did you get that figure? Did you do 10 factorial or something? Isn't it as simple as 10^10?\n\nEdit: you did do 10!, that's for a combination of things that exclude what's already been used and can't be used again. So a line of x amount of people has x! Combinations, you can use it that way because there can't be 2 tims, but phone numbers can have 2 7s",
"10 digits is 9,999,999,999 combinations. Sure there are rules, unused area codes, the 555 exchange number, but it's still more than the number you suggest. Under the [North American Dialing Plan (the rules)](_URL_0_ ): Each three-digit area code may contain up to 7,919,900 unique phone numbers: NXX may begin only with the digits [2–9], providing a base of 8 million numbers: ( 8 x 100 x 10000 ) . However, the last two digits of NXX cannot both be 1, to avoid confusion with the N11 codes.",
"You are using the wrong formula. I believe you are doing 10x9x8x7x6x5x4x3x2x1. This formula implies that once you use a digit in a phone number, that it cannot be used again. So 403-555-6812 would be invalid in your formula because 5 is a repeated digit. \n\nInstead you want 10x10x10x10x10x10x10x10x10x10. Because every number has 10 digits AND each digit can be used multiple times in the same number. "
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4l5sjd | seeing as video/picture quality is constantly increasing (1080p, 4k etc..), is there a limit to the quality that the human eye can notice a difference? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/4l5sjd/eli5_seeing_as_videopicture_quality_is_constantly/ | {
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"Theres alot of conversation about this actually...\n\nYou really need to focus on DPI, since 1080p is very different on a 20\" tv vs an 80\".\n\nBut then it matters how far away it is, and how good your vision is...\n\nSome would say we already eclipsed that limit with 1080p tvs at normal viewing distances. Yet... its trivial for a person to identify a 4k vs 1080p tv. Could they be seeing other advantages? better color? better source content? or is it something more than just how many rods and cones we have in our eyeball?",
"It's a very interesting question. [Here is a 3000+ vote explanation you could find with search](_URL_0_ ). "
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2yktlq | how do studios get to film in places as dense as new york without interrupting business and traffic, while also not being interrupted during filming? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2yktlq/eli5_how_do_studios_get_to_film_in_places_as/ | {
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"The majority of the time, it's just green screen. [Here's the VFX video for the Time Square scene in The Amazing Spider-Man 2.](_URL_0_)",
"I've got 10+ years working in the industry, my father was a camera operator and my grandfather was a Director/Producer of stage, TV and Film.\n\nThe studio, via the production coordinator/manager, makes an agreement with the city, and they provide Police assistance to close down the area the crew wants to film in. Sometimes they simply use squad cars to block off the area, other times they use small, lightweight barriers, it depends a bit on how large and busy an area they need to close off. The city gets a huge fee to cover their costs (and a little extra) and businesses in the closed area are given a compensation for lost income.\n\nThe city usually has stipulations on timing, and they generally try to avoid letting crews use any tremendously busy areas during normal business hours, especially in places like Times Square and the corner of Hollywood and Highland, which are huge thoroughfares for traffic and also cater to huge numbers of tourists who will be blocked from spending their money while filming is ongoing. However, this isn't a non-negotiable policy, if there's enough money on the table and the blockage will only be for a few hours, it can happen. Because of the cost and logistics, they usually try to expedite the process and be in and out as quickly as possible.\n\nIt's also worth noting that soundstages and backlots around the world have a nice collection of extremely convincing recreations of certain areas, so there are many cases where they simply use a 2nd unit crew to get exterior footage of the actual area, and then film the rest of the scene on a lot or in a stage. Also, green screens - see the Times Square footage in the 2nd Spiderman, per another user's response.",
"I lived in NYC in the early 2000s. I worked in a restaurant right in the heart of the business district. 51st n Lexington if I remember correctly. On Saturdays the area is almost a ghost town. One Saturday i go in and they have a good portion of Lexington blocked off. There was fake snow and a couple different yellow cabs with cameras all over them driving around. It was pretty neat",
"Wall Street during the weekend is a desert. Many movies use that area due to that fact. They still have police assistance and all, but it helps.\n\nFor other areas, a lot of logistics and closing down stores happen.",
"And sometimes it isn't even New York, in Captain America The First Avenger [it was Manchester UK](_URL_0_) that stood in for the Big Apple.",
"In addition, Toronto Ontario is often used as a stand-in for New York city.",
"I lived in LA and have had to deal with movie's and TV film crews. Long story short. They do get in the way and mess up traffic. The reason they don't get interrupted is because they pay the city and any business's or residents around to close off the area they are using. It costs a lot of money and the cities love when then go over their time and have to buy another permit. In terminator 2 when the terminator rides his motor cycle off the bridge and into the aquaduct to stop the T1000 chasing john in the semi, was finished filming 5 minutes before their permit was up. There were cops there reminding them and telling them they would be shut down.",
"I had the same question - specifically about Ken Block's 2012 closure of most of San Francisco; I know he's sponsored by DC Shoes, but I've always wondered how many millions of dollars that 10 minute film must have cost; you can see at some of the places, there are multiple tracks there when he arrives, indicating that he's taken a few runs through previously. They must have shut down those parts of the city for a couple of hours, at least. ([link](_URL_0_) for reference)",
"I can't believe this hasn't been mentioned yet...PRODUCTION ASSISTANTS. I am a production assistant and my job is essentially to make sure that pedestrians don't walk into the shot and that they (as well as the crew) are quiet. Yes, cops help sometimes when there is a street scene (cars, walking in the road, etc.) but 90% of the time the PAs are the ones who make the permitted areas able to be filmed in.\n",
"They also often film off location in quieter areas that are/are mocked up to look similar. For example World War Z; a chunk of the movie was film in Glasgow, Scotland because it looked a bit like Philadelphia and is a lot quieter and cheaper to use. "
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cintr9 | why do large amounts of flammable material in a small space explode (ex: gasoline can) when ignited instead of just lighting on fire and burning like wood | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/cintr9/eli5_why_do_large_amounts_of_flammable_material/ | {
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"Burning causes things to expand, heat up and release gases. if its in an enclosed space such as a pipe, grenade casing, gas can, etc... then the pressure from these reactions builds up causing the big bada boom.",
"Whether a mixture of air and gas is combustible depends on the air-to-fuel ratio. For each fuel, ignition occurs only within the explosive range (i.e., the lower and upper explosive limits). For example, for methane and gasoline vapor, the explosive range is 5-15% and 1.4-7.6% gas to air, respectively.\n\nSo a sealed or partially sealed can of liquid gasoline wouldn’t actually explode. The top layer would burn and consume oxygen, but it can’t burn faster than it consumes oxygen. However, a can of gas vapor at the appropriate concentration would explode.\n\nSame goes for wood. A block of wood will burn steadily, because the exposed surface area is limited. However, if sawdust is thrown into the air it can combust rapidly because the individual grains of sawdust have more exposed surface area and more available oxygen. This is why sawmills and grain silos blow up every now and then.",
"chemical reactions often create gases. gases want to expand. If they are confined into a casing they instead build up pressure. Usually the pressure rises till the casing breaks under the pressure, and the high pressure is released very fast. that is an explosion. If your casing is stronger, you get a bigger explosion.\n\nOpen flames also create gases, but they don't build up pressure, as the gas can easily expand into the open air. The only way to get an explosion with an open flame, when the flame spreads faster than the pressure can relax into the air (which happens at the speed of sound)."
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1e5jox | warm fronts | I get how cold fronts work and how cold air is more dense which pushes the warm air out of the way as the warm air rises, but how does a warm front work? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1e5jox/eli5_warm_fronts/ | {
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"Warm air moves to an area where there is already cold air.\n\nAs the warm air moves into the new area, it gets pushed up on top of the cold air.\n\nUnlike cold fronts, the weather at warm fronts tends to be stable. In other words, as the warm air rises and cools, it becomes dense enough that it's not going to continue rising and rising.\n\nBecause of this, warm fronts tend to have lots of \"stratus\" types of cloud, that means layers of cloud (rather than big, bumpy clouds), and a warm front would normally be associated with persistent drizzle and rain (whereas cold fronts create lumpy \"cumulous\" clouds, and are associated with heavy rain showers)."
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5mq0ag | why does a weak am/fm radio signal result in a consistent static/fuzzy sound while a weak satellite radio signal results in intermittent high quality sound? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/5mq0ag/eli5_why_does_a_weak_amfm_radio_signal_result_in/ | {
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"The simple answer is that AM/FM is an analog signal, which you can \"kind of\" pick up. Think of analog as a scale of 100-0 with the quality increasing or decreasing as you move from the transmitter.\n\nSatellite radio is a digital signal. Think 1 or 0. It's either there, or it's not. The same holds true for satellite TV, where in a severe storm your picture will be perfect right up until it cuts out into nothingness.",
"This is one of the major advantages of digital broadcasts over analogue. \n\nWhen your analogue AM/FM radio signal is weak you start to hear background noise and interference because it becomes difficult for your receiver to distinguish between signal and noise. Even on modern analogue devices, the internal filtering can't tell if the crackling static is part of the real signal or not when it's weak.\n\nDigital is either received or it isn't. If the digital signal is weak then the receiver just doesn't give you noise since it has nothing to decode. Whereas analogue actually transmits something directly related to the audio you hear, digital is just 1s and 0s. Noise and interference just make it hard to tell what's being received - they don't change 1s to 0s or 0s to 1s. Noise on analogue still turns into noise which you can hear. ",
"Broadcast radio is (mostly) analog. That means if you get a partial signal, you can get a partial.\n\nSatellite radio is digital, which means all or nothing.\n\nIt is kind of like talking in a noisy room. \n\nIf we are just having a conversation and you miss a word or two, you can probably guess from the context what I am saying. \n\nBit if I am trying to give you a phone number, and you miss a few numbers, they numbers you do hear aren't going to do you much good."
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1myhvz | why are anarchists and nihilists put on the same political wing as socialist and communists? | Why are anarchists and nihilists put on the same political wing as socialist and communists? Both the anarchists and nihilists want the governing state gone. Isn't that just extreme liberalism? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1myhvz/eli5_why_are_anarchists_and_nihilists_put_on_the/ | {
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"If you look at it economically, anarchism has strong ties to socialist/communist theory. Anarchists are pretty misunderstood, it's not all about no rules and complete chaos. Early anarchists believed that you should grow food, and whatever extra you had you should give to your neighbours for free, and vice versa. This idea is basically the opposite of capitalism, where you pretty much want to make as much money as you can off of your extra food. That is just one example of policy why it is on the left, rather than the right. ",
"There are different forms of anarchy, but one of the earliest is radical collectivism. The collective still has management but is has no leader (what anarchy literally means).\n\nAs you can imagine collectivism has a lot in common with communism."
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6r5lln | how is something scientifically proven to be a fact? | Co-worker of mine has issues with what we consider to be facts and that we're all programmed to believe 1+1=2
It's quite a headache talking to him about anything, mostly because I'm not a damn scientist. So how can I break down the way scientists prove their discoveries and how they become facts and truth? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/6r5lln/eli5_how_is_something_scientifically_proven_to_be/ | {
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"Scientists don't tend to use the word \"fact\" for any generalized statement.\n\nI dropped a ball from the top of a 100-meter building and I measured that it took 4.9 seconds to reach the ground. That's a *fact*. It's evidence consistent with the theory objects on Earth fall with an acceleration of approximately 9.8 meters per second squared.\n\nThe theory of gravity is our complete understanding of gravity based on all of the evidence we've collected. It takes into account things like wind resistance, so a feather falls more slowly than a brick. It takes into account the masses of the various objects involved, and it also takes into account Einstein's theory of relativity, which changes what happens pretty dramatically when the velocities involved are large.\n\nThe most important thing about a scientific theory, to me, is that it makes useful predictions. It says that given a certain situation, here's how to apply the theory to predict the outcome.\n\nIf it's right, it's a useful theory.\n\nYou can disbelieve the theory of gravity all you want, but that doesn't make it any less useful. If you can find a counterexample - some evidence that it's wrong under a certain set of circumstances, then the theory *must* change to incorporate that new evidence, if it can be reliably reproduced and the current theory is inconsistent with it.\n\nIn the case of 1+1=2, that's one of those things where as long as we all agree on the definitions of numbers and addition and equals, it's definitely true, but there are other scenarios where it's not true (like one cloud plus another cloud equals one larger cloud).\n\nWe don't talk about 1+1=2 just as an exercise, we talk about it because it's useful. We have problems to solve and math helps us get at the answer. If the answer we get is wrong then it's not very useful and then there'd be no point!\n",
"Math is a bit different - its truth is largely self-demonstrating. As for science, we never claim to know anything with certainty the way mathematicians do. But when we think something is true, we look for every alternative explanation we can, and we try to prove ourselves wrong. And since every new thing we learn depends on other things we think we know, our ideas get tested over and over again. The same is true of a lot of modern technology. If we were wrong about the principles on which that technology is based, it couldn't work.",
"In science a fact is an observation. Basically it's something that anyone can see for themselves, at least if they have the right equipment. The sun is in the sky right now. This is a fact, anyone can look up and verify it for themselves. If I take one object, and put one other object next to it, I now have two objects. This is a fact, anyone can verify this observation. \n\nThen there's theory and there's law. Despite a common misconception, these two terms are equal to each other in terms of factual support. A law is an observation that can be applied anywhere in the universe for the same conditions. Two objects will have a force of gravitational attraction to each other determined by their mass and the distance they have from each other. Given enough time and data, you can independently verify this observation for any two objects in the universe, thus it is a law. A theory is an *explanation* of observations. So the law of gravity tells us what gravity is, a force of attraction between two objects, while the theory of gravity creates a working framework to explain why gravity occurs (because large objects distort space, and the distortions are more pronounced the larger the object). Both the theory and the law are based on the same facts, but they have different purposes.\n\nAs a personal observation, your coworker sounds like he's being contrarian for the sake of contrarianism, or he thinks he's a lot smarter than he actually is.",
"You asked specifically about 1 + 1 = 2.\n\nHere's one way to look at it. It's just a way to write down the following observation about the universe:\n\nI have this apple ( ).\n\nThere's another apple over there ( ).\n\nIf I go get that other apple, then now I have these apples: ( ) ( ).\n\n( ) + ( ) = ( ) ( )\n\n1 + 1 = 2\n\nThat's not really a great way to be rigorous about math, though, so here we go. I'll try hard to keep it ELI5.\n\nThere isn't anything universal or fundamental or magical about a given mathematical system.\n\nWe just write down some rules that we ASSUME are true. There isn't anything special about them. We just say \"here are the rules I am going to assume are true.\" These are called axioms.\n\nEverything else about the mathematical system is a direct result of the axioms.\n\nSo, let's see what we can do about 1 + 1 = 2. Those are all natural numbers (0, 1, 2, 3, ...).\n\nThe usual set of axioms for the natural numbers is called Peano's Axioms. _URL_0_\n\nThere are 8 axioms, but they can be divided into 3 parts.\n\nPart 1: Axiom 1 says that 0 is a natural number.\n\nPart 2: Axioms 2 through 5 describe how \"=\" works.\n\nPart 3: Axioms 6, 7, and 8 describe how S(n), the successor function works. Basically, for some natural number n, S(n) gives you some new natural number m, and you can only get m from S(n), not S(any other number besides n).\n\nThat's enough to give us all the natural numbers. \n\n0 is a natural number. \n\nS(0) is a new natural number. You can only get it from S(0), not S(any other number). Since it's the first natural number we get after 0, let's also give the number S(0) the convenient shorthand label of \"1\".\n\nS( S(0) ) is another new natural number. You can only get it from S( S(0) ), not S(any other number). Since it's the natural number you get after S(0), which we have labeled \"1\" for convenience, let's give the number S(S(0)) the convenient shorthand label of \"2\".\n\nThese are just labels. 1 is just shorthand for S(0), and 2 is just shorthand for S(S(0)).\n\nNow, let's figure out +.\n\n \"+\" is just another function. We define it as follows.\n\n(1) a + 0 = a\n\n(2) a + S(b) = S(a + b)\n\nSo, about 1 + 1 = 2.\n\nWell, 1 is really S(0), so we want to know what S(0) + S(0) is. \n\nFrom (2):\n\nS(0) + S(0) = S( S(0) + 0)\n\nFrom (1), S(0) + 0 = S(0), so:\n\nS(0) + S(0) = S( S(0) )\n\nGiven the rules we started with, that we simply assumed are true as the basis for our system (Peano's axioms), and how we defined \"+\", it MUST be the case that S(0) + S(0) = S( S(0) ). It is impossible to get any other result. \n\nNow, we replace S(0) with its handy shorthand \"1\":\n\n1 + 1 = S(S(0))\n\nNow, we replace S(S(0)) with its handy shorthand \"2\":\n\n1 + 1 = 2. \n\nSo, in the system where we assume Peano's axioms are true, and in which we labeled the number S(0) with \"1\" and the number S(S(0)) with \"2\", it must be the case that 1 + 1 = 2. It is impossible to get any other result.\n\nIf you start from different axioms, or you apply the labels \"1\" or \"2\" to other numbers, then it may or may not be true that 1 + 1 = 2.\n\nYou can even pick a set of axioms so that 1 + 1 = 2 is true if you get there one way and false if you get there a different way. That set of axioms would be called \"inconsistent.\" A \"consistent\" set of axioms is one where if you can prove a statement is true, you can't also prove that it is false, and if a statement is false, you can't also prove that it is true.\n\nGenerally, only sets of axioms that are consistent are useful.\n\nPeano's axioms are consistent.\n\nAs a side note, I agree with the other posters that your coworker is a pedantic ass. While there's a way in which what he says is technically true (\"What if I say that \"1\" is actually the label for the number S(S(S(0))), that you normally call \"3\"?\"), it isn't really meaningful or relevant or important or worth wasting time thinking about.",
"These people are getting way too into this. In the most basic way possible, a \"scientific\" fact is anything that can be tested, preferably under the same conditions, and will give the same results time after time. I use scientific in quotations because there are some things that are accepted as fact without needing to be tested, such as 1+1=2. Just remember when in doubt: Extraordinary claims require extraordinary proof."
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6l9pcx | feces being a major source of harmful germs,how is it the lower intestine isn't chronically infected. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/6l9pcx/eli5_feces_being_a_major_source_of_harmful/ | {
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"This has to do with the fact that our intestines are made up of microscopic nutrients collectors (imagine a fluffy rug and roll it) [i don't know how it's called in english.] So tiny that bacteria can't fit through them but the nutrients however can. \n\nBacteria decompose food in our intestines which then get absorbed into the bloodstream via the hair-like collectors. But bacteria never get into direct contact with the blood and so it never infects our bodies. (But if for example a perforation occurs in the intestines, there's a big risk of infection cause it disrupts this barrier.) \n\nOn the other hand if you come into contact with feces \"outside\" the bacteria can get into your body much easier through little wounds and mouth (if you don't wash your hands properly.) ",
"The vast majority of the bacteria in your colon are (mostly) harmless organisms that have evolved to live with us. The high populations of these bacteria tend to suppress the growth of other, harmful bacteria. Think of an apartment building with 100 units. 98 of them are already occupied by quiet residents. Even if the other 2 units are occupied by hooligans, they can't cause a lot of trouble and that trouble can't spread.\n\nNow these bacteria aren't completely harmless. The very common E. coli bacteria causes infections ranging from mild (simple urinary tract infections) to life threatening (sepsis of the blood) if it gets somewhere it isn't supposed to be.\n\nWhen we kill off the friendly bacteria, sometimes less savory ones take their place. A bowel infection known as C. difficile colitis is typically caused when antibiotics kill off the benign bacteria, leaving it behind. And some bacteria are just bad actors (like Salmonella or Shigella) and can cause infections even in healthy colons.\n\nThe colon itself as another poster noted is resistant to invasion from most gut microbes."
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3g6oo4 | what are ghz and what do they mean when it comes to computer specs? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/3g6oo4/eli5_what_are_ghz_and_what_do_they_mean_when_it/ | {
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"ctvd4t9"
],
"score": [
3
],
"text": [
"Hz is a measure of frequency- the number of times something happens per second. If something has a frequency of 3GHz, it means that it happens three billion times per second. \n\nIn the case of computers, that's the speed of its internal clock. A single operation in a computer can take multiple steps, and the clock speed tells you how long it gives each step to complete. A simple operation, like addition, might only take 1 clock tick to complete, while a more complex operation like trig functions, can take over 100.\n\nClock speed by itself doesn't mean much. You can use it to directly compare processors of the same series (so you can compare a 4th gen Core i5 with another 4th gen Core i5 processor), but different series of processors take different amounts of time to complete each operation, and a 3GHz processor that can finish a task in 100 clock cycles is faster than a 4GHz processor that takes 200 cycles to do the same work. "
]
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[]
] |
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8roqmg | when a hard drive sets aside space for a download, what is it filled with before it actually receives the data that takes up the space? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/8roqmg/eli5_when_a_hard_drive_sets_aside_space_for_a/ | {
"a_id": [
"e0t05xc"
],
"score": [
6
],
"text": [
"Logically, the filesystem is told to reserve the physical space for the new file.\n\nPhysically, the space of a hard drive that are reserved still contain whatever data was last in that space."
]
} | [] | [] | [
[]
] |
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