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73yav3 | Why do US based airlines lag behind in service and quality, especially in their premium cabins? | Anything from ground service, to in flight food, how can an economic powerhouse like the US have such universally poor quality airlines? (Certainly I'm not talking about safety.) I don't see any US-based carriers on this list of top airlines: ANA All Nippon Airways Asiana Airlines Cathay Pacific Airways Emirates Etihad Airways EVA Air Garuda Indonesia Hainan Airlines Japan Airlines Korean Air Lufthansa Qantas Airways Qatar Airways Singapore Airlines Swiss Thai Airways Turkish Airlines EDIT: I wanted to add 2 cents from Gary Leff: "What I desperately wish I could remember is which of these books it was where I read extensively on United Airlines President Pat Patterson. Patterson had been the Wells Fargo loan officer who authorized funding for Pacific Air Transport, later acquired by Boeing Air Transport, which was ultimate merged in with other carriers to become United Air Lines. Patterson moved over to Boeing and then to United, becoming General Manager and ultimately President of the airline. While he’s perhaps best known for approving the hiring of in-flight nurses which morphed into onboard flight attendants, he’s also more than any other, the man who brought union control into the operation of the airline business. The version of the story I recall is that he believed that the unions were closer to their workers, and better understood their needs, than management was. It wasn’t just a matter of collective bargaining, but deeply held belief, that the workers would be better off (and that this would benefit the airline) if unions and union procedures handled scheduling. I’m not a scholar in this area by any means, but the shift from company control over its employees to union control — and from management evaluation of employees to roles and responsibilities determined by seniority — has consequences which reverberate across the industry today. Great flight attendants provide great service because they’re proud to do so, because they’re driven to do so, internally. In some ways the exceptional US flight attendant deserves much more praise because they are doing it on their own, when there is little if any benefit to them to do so. They aren’t going to lose their job as a result of occasionally grumpy and often lackluster service. They aren’t going to get paid more for going above and beyond for a customer. They do it because they’re internally driven and believe it’s the right thing to do. I truly thank them and honor them. But as long as scheduling is done by seniority, and pay is doled out by route, and as long as commendations and criticisms are only ancillary to performance evaluations, pay, and perks, airlines aren’t going to be able to align the incentives of their frontline workforce to deliver outstanding service. It isn’t all institutions, and it isn’t all culture, but the two of them combine so that superior companies drawing on service cultures and fostering those cultures can provide a superior experience. Mediocre companies drawing on a service culture will offer good and bad, just as companies here in the US without strong service institutions will occasionally offer flashes of brilliance (but often ‘good enough’). And in most cases I don’t expect either the cultures or the institutions to change very much." | Economics | explainlikeimfive | {
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"A good number (but not all) of those airlines are subsidised by their government for political/ prestige/ strategic reasons, so a $100 ticket buys you $150 of product. Emirates/ Eithad/ Qatar especially don't have business models that would survive without outside money.",
"Us airlines are public companies backed by institutional investors. They are evaluated on cost efficiency. This means that they tend to provide bare minimum service with the smallest staff and fewest amenities.",
"Airline passengers in the US have voted with their wallets and demonstrated that when they are paying for their own ticket, all they care about is price. The only people willing to pay for a premium flight experience are people spending someone else's money. Second, US airlines are heavily built around their domestic routes. International operations are an entirely different market with different service standards. To put some numbers to this, as of a couple years ago, American Airlines saw half of its revenue come from the 87% of its customers who flew the airline only once that year. When looking at their fortress hub in Dallas-Fort Worth, they don't see their competition as United or Delta, but rather ultra-budget airline Spirit. URL_0",
"I believe it comes down to price. URL_1 [ranks countries by average flight costs per kilometer]( URL_0 ). In the US, we're about halfway down the list at an average of $11.50. That puts is two slots above China, which isn't exactly known for expensive prices. That's because in the US, a lot of people fly to and from work in coach. People generally want the cheapest flight possible, even if they end up with a bad experience. By comparison, I've been told that flying in Japan is more of a luxury. When a good experience is more important than cost, you end up with more enjoyable flights.",
"Because the wow or cool factor has worn off of airline flight and has been replaced with a business model that the plane has just become a greyhound with wings.",
"I hope this doesn't sound mean, as it's not meant to be. One of the other factors in how people assess the quality of their airline experience is by interactions with the employee they spend the most time with, which is the flight attendants. Now, I used to work in a hotel in DC where a LOT of the flight attendants for several of the above airlines would overnight. Almost universally, the flight attendants were female, between the ages of 20-28 (roughly), happy, and attractive. Contrast that with the average flight attendant on a US flag carrier flight, I'd say 50-ish, and either a tired grumpy female or a tired grumpy gay male. They just don't look like they enjoy their job at all, and the passengers pick up on that attitude, even though they superficially camouflage it. So which would you rather deal with, a happy smiling 24 year old girl or a bitchy 55 year old woman who hates you being there? And yes, I know this sounds very superficial, and yes I know there are lots of flight attendants who don't fit this profile, but I would say that the general trend I've noticed over the past ten years, and dozens of flights. I've always felt that the foreign airlines have the customer service part squared away, where as the US airlines don't. And you know it's funny, because if you go into a store or restaurant in Europe, the customer service is TERRIBLE, but in the US it's great by comparison. Funny how the shoe is on the other foot when it comes to airlines.",
"Because when you are in Japan/Singapore/Qatar/Korea/etc, and you are getting on an airplane, you are far more likely travelling internationally than if you are an American, who's more often than not getting on a domestic flight, even for only a few hundred miles. International flights are always different than domestic ones.",
"Answer is already in the thread elsewhere - capitalism. Came here to say Singapore Air sucks ass in my experience. Fine if you're a rich dude, terrible if you're anything else. Wife and I flew to New Zealand from the UK with them for our honeymoon. Spent our savings on an upgrade to economy plus - why not, you only get one honeymoon right? And it's a 28 hour flight. Treated like shit from start to finish. Wife was ignored by all stewardesses (attractive females in their early twenties as mentioned elsewhere in the thread), both of us generally overlooked for drinks, my entertainment system didn't work and they didn't care, sat on the plane watching them turn the flight around at a short layover, they reused pillows and blankets, the list goes on. Changed to New Zealand air for the final stretch, that shit was the bomb. And their safety video features the all-blacks doing a rendition of the men in black theme with safety related lyrics.",
"In order to keep flights near capacity airlines have aggressively maintained the price of many tickets for years. I flew for the first time 17 years ago and the same flight today is the same price it was then. Quality is irrelevant because they know a majority of consumers book strictly based on price. Even the crazy margins for luxury flights like Emirates would barely dent the cost of operating fleets the size of large carriers.",
"Americans fly a large amount, and the airlines are mostly deregulated. This means they end up competing on price, rather than on quality.",
"* many airlines outside of the US are subsidized by their country's government * in the US, being a flight attendant is a mid-range job, in less developed countries, it is pretty high-end, with more competition, and the people get those jobs are more motivated to keep them * in less developed countries, only the rich can afford to fly, so the airlines cater to them more...in the US, most everyone can fly, and most everyone is happy to take the cheapest flight they can * in developed countries, air travel isn't as impressive as it once was...pilots used to be a step down from astronauts, now they are glorified bus drivers, so airlines have less of an image to maintain for the public"
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73yjw6 | My kids Dinosaur book said scientists don't know what skin color they were, but it said scientists had good guesses but didn't go into detail. How and why would they make these guesses? What are they? | Biology | explainlikeimfive | {
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"We can make educated guesses by looking at their possible environments and comparing it to reptiles in present time.",
"My son has the same book I think. But, I saw on the internet that they supposedly found a fossil with some preserved skin. I dont know how to link it like it should be, but here, we thought it was cool ... URL_0"
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73ynt9 | How does the Home Owners Association (or HOA) Function? | I'm Australian and just don't understand the idea of signing away the ability to do whatever the fuck you want with what you paid for. Also how do they fine you? Isn't it a private enterprise? | Economics | explainlikeimfive | {
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"The idea behind a HOA is to get the neighborhood working together for their own benefit. A lot of things is shared between the owners of a neighborhood such as parking spaces, sidewalks, fences or even walls and roofs. The HOA is the owners who join together to maintain these things. They also might help each other when things needs to be done, for example when it is time to paint or do maintenance on the properties it is cheaper and better to do on a larger scale. The disadvantage of a HOA is that it attracts people who want power.",
"The basic premise is that the HOA keeps out the type of riff-raff that drives down property values. They can't really do that explicitly, so they do it in ways that prevent those types of people from wanting to live there in the first place. An HOA is typically privately held, but they can fine you because by joining the HOA, you agree to pay fines for violations."
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73yzyz | Why does touching my face a lot cause pimples but the rest of my body isn't affected the same way? | Biology | explainlikeimfive | {
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"Number of sweat glands, oil glands, and general sensitivity. Skin on your face is a lot more sensitive than your arms or back for example.",
"30 year acne veteran here. If you suffer from acne, your face already contains a lot of \"proto pimples\"-- pores that are on their way to pizzaville for a variety of reasons, including blockage, misshapen exit to the surface, simmering infection, skin mite allergy, or whatever it is that constitutes your personal acne hell. Other places with these issues might include your shoulders, back, butt, whatever. Parts of the body with no acne situation are not bothered by touching, just like water is not flammable. But if you do have any of these incipient war zones, pressure does them no favors at all-- it makes the pore even more blocked, or drives bacteria deeper in, or bursts open the sides of a simmering infection, or otherwise tips the balance from \"uh oh this may become a problem\" into \"mayday mayday\"."
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73z2g4 | How did we measure the speed of light so precisely? | Physics | explainlikeimfive | {
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"The most accurate measurement we have of the speed of light was made in 1975. They did this by using the following simple equation: > c = fλ Where c is the speed of light, f is the frequency of the light and λ is the wavelength of the light. They used high *spectral stability lasers* and *accurate cesium clocks* to determine the frequency and the wavelength. A high spectral stability laser means the number of different frequencies (and wavelengths) of light it emits is as small as possible. You want the light to be made of 1 frequency only, but this is physically impossible to do, so you have to get as close to that as possible. You can read [here]( URL_0 ) for a brief history on the measurements of the speed of light.",
"Here is how you do it, and its super easy. You get two circles and you punch a small hole on the edge of each one. Then you put them both on a stick that rotates (imagine the tires on a car on their axle). Now you just shine a flashlight through the hole and see how fast you can spin the wheels before you no longer see the light. From there its just some math that any kid in high school can do based on the side of the holes, the rotational speed of the wheels, and you get the speed of light."
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73z2qp | Why has MH370 not been found? | Other | explainlikeimfive | {
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"The area that the plane could be is enormously large. There are lots of reasons for this, but the fundamental problem is just finding a relatively small object in an extremely large ocean. It's hard to conceptualize the size, but a Boeing 777 is about 500 m^2 in area, and the area of the sea searched for the plane was about 4.6 million km^2, or 4,600,000,000,000 m^2. So this is approximately the same as trying to find a single grain of sand (about 1 mm^2) in two White Houses (each about 5000 m^2) when the floor of the White House is several thousand meters under water.",
"Modern passenger aircraft are able to fly very long distances so the search area is very large. The aircraft were also trying to avoid being spotted by radar. The radar coverage in the area is poor as it is cheaper to use transponders then traditional radars, but as the aircraft switches off its transponders it is useless. There is also a lot of ocean in the search area which makes it much harder to find the fuselage on the bottom of the sea then if it were on land. We have found debris floating on the surface and on beaches but nothing more.",
"There are multiple reasons which led to the current situation. 1. The time between the disappearance of the plane and when it was detected 2. The switched off transponders, so we have just for some time an idea where the flight was directed 3. Who or what flew the machine finally; in the first it headed direction Langkawi but then surrounded Sumatra / Indonesia and took a souther path 4. The MH370 was not equipped with a Satellite supported tracking system and it was out of reach of terrestrial (radar) And finally, the Indian Ocean is just as big as hell and deep as well. In the moment, the battery of the Black Box was drained out there is only a guess or extrapolation left where to search."
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73zcbn | Why are bodies able to create an entire body with it's own lifetime supply of regenetive cells, but is itself unable to prevent gradual decay over a lifetime? | Biology | explainlikeimfive | {
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"It's a lot like a car. A new car you want to repair and replace as much as you can. As the car ages, it gets more expensive and time consuming to repair, and easier to just replace the whole thing. Now consider that evolution is about what survives and prospers as a species. And consider the innumerable dangers that could destroy an organism. Nature has a few creatures that do effectively live forever, but as a general rule, replacing constantly works better, so that is what prospered and spread. Also note your own body does the same thing. Rather than make cells that never die, it constantly removed and replaces cells. It's such a good system that some of your cells even self destruct or kill other cells to make this happen. Further, note that replacement allows evolution to happen faster. The shorter a creature lives before procreation and the less it sticks around after, the more changes will happen. Edit: to summarize, it's possible, but evolutionarily speaking, not desirable. Creatures actually moved away from that as time went on.",
"Because as cells duplicate, they lose a little bit of DNA on the top and bottom. The first few times it doesn`t matter, because the DNA lost is \"Junk\" DNA, or DNA that doesn't serve any other purpose, but eventually all the Junk DNA is removed and the cell can no longer duplicate because it would lose essential DNA.",
"Evolution didn't push us to live forever, it pushed us to live just long enough to produce and care for the next generation long enough for them to be independent. Our genes \"don't care\" about us or our lives, they \"want\" to replicate themselves.",
"Lifespan is related to cancer. The body has a cellular clock that will tick down as the cells replicate (telomeres), providing a significant barrier to the development of cancer: if you grow out of control but don't surmount this mechanism, you will eventually die. New bodies are produced from a single cell (egg+sperm) that starts this clock all over again. If this cell is defunct in some way and doesn't replicate properly, it is basically just ejected and you try again. The loss of an embryo is not significant to the organism Brief edit: to clarify, the clock is deliberate, you trade likely dying from cancer at the ripe age of 4 for an eventual expiration date",
"A lot of typical \"telomeres\" answers, but that's BS. Your body can create eggs in which the telomeres are restored, allowing for a new human baby that can then continue to grow up normally. Thus, clearly a mechanism exists to correct the loss of telomeres (i.e. [telomerase]( URL_2 )). Further, research with rats has shown that disabling telomerase has little to no effect on the health or aging processes of rats for up to 6 generations. The answer to your question is currently not well understood but appears to be related to the scientific field known as \"[epigenetics]( URL_1 )\". Epigenetics is the study of how gene expression changes over your lifetime and how these changes in expression can be handed down over generations. Ask yourself this, why is it that every cell in your body has the same DNA and yet some cells grow up to be skin, others to be brain or muscle or liver? Epigenetics! i.e. the selective expression of some genes over others. The reason an egg can become a new human that doesn't possess the age of its parent is because the epigenetic markers of the parent are \"reset\" when the egg is produced. This suggests that age is a process by which epigenetic changes accumulate over the life span of an organism. These changes may be somewhat programmed to happen, but are also influenced by environment (e.g. toxins from smoking that reduce life span). [In fact, your age can be \"guessed\" to within about +/- 5 years just by counting the number of epigenetic markers in your DNA.]( URL_0 ) So, to answer your question, the most likely cause of aging is that we are in fact programmed to do so. We die because evolution wants us too. Death is advantageous to life and so it is programmed into the very fabric of our being.",
"I'm fairly certain the primary cause of this is reduction in the length of telomeres at the ends of your chromosomes although it's been a while since I've taken Biology"
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73ze7h | The universe is expanding, but where is the center of the expansion? is that the point in which the big bang happened? And where are we relatively to it? | Physics | explainlikeimfive | {
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"Every point is expanding away from every other point. There's no \"center of the expansion\". Imagine an infinitely large rubber sheet, with a 1\" grid drawn on it. Now stretch out the rubber sheet so that the grid lines are 2\" apart instead, everywhere. Is there a \"center\" to this stretching? Every point is moving away from every other point.",
"If you were to bake a fruitcake, you put the raw mix into the oven and it begins to expand and rise. The pieces of fruit inside the cake are moving away from each other inside the fruitcake mix. From each piece of fruits perspective every other piece is moving away from it. If there is any center, then the individual piece is it because every other piece is moving away with expansion.",
"The idea is that space itself was a product of the big bang. So every point around you and in the universe was concentrated at a single point at the beginning. This would make every point in the universe the center of the universe. So the universe is expanding relative to every point in the universe. A result of that is that no matter where you look from, the universe is always expanding outwards."
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73zgk1 | What is regulatory capture and how does it work? | Other | explainlikeimfive | {
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"TL;DR: It's a fancy name for the legal equivalent of having the foxes guard the henhouse. Okay, so let's say we've got an industry in need of regulation. Doesn't really matter what. So the federal government creates an agency to regulate it. Great. Question: who do we want running that agency? Presumably, we want people with a working knowledge of the industry to be regulated. After all, if the industry is *important* enough to be regulated in the first place, it's almost certainly *complicated* enough to be beyond the grasp of even the most educated people that don't have any special insight into the details of the subject matter. Of course, the only people that have a working knowledge of any particular industry tend to be people that *work* in that industry. And if we're going to be realistic, a person with experience in an industry that takes time to work in the agency that *regulates* said industry is going to be *incredibly* valuable as an employee after they finish working for the agency. So we see what's often called the \"revolving door\" effect, where a highly-placed executive in an industry will do a stint heading up the relevant regulatory agency, only to go straight back to industry after their term is up, often at an even higher salary. This creates all *kinds* of conflicts-of-interest that conspire to produce the phenomenon known as \"regulatory capture\". Examples: * Someone with a background on the industry side of things will probably have a *perspective* that's biased towards industry. \"Oh, yeah, I remember how annoying the agency was a few years ago when we wanted to do X. I'm going to make sure the agency doesn't give anybody problems about X now that I'm at the helm. * Someone who just left a particular company may feel some loyalty to that company, or at least to the people in it. * More broadly, high-level executives in a particular industry usually all know each other pretty well, often on both social terms in addition to professional terms. These relationships can be *exceptionally* chummy, to the point that it's reasonable to think that suddenly giving one of them a regulatory role wouldn't be enough to overcome personal bias. * Someone who leaves industry to work in an agency but expects to go right back to that industry after a few years may well, consciously or unconsciously, be biased towards the industry in general or particular companies for which the person wants to work afterward. \"Hey, you should hire me. I did you a solid with that one thing when I was at the agency.\" It's a real problem. And not a problem that's easy to solve, because the only people who *don't* have these kinds of conflict of interest are people that don't have any expertise in the subject matter. The line between \"understanding an industry\" and *having* an understanding *with* an industry\" is both really blurry and really hard to avoid."
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73zjjt | Why is the economic value of a task different in different countries? | For example, I might earn 30 USD to manually dig a hole in the US. However in a 'poorer' nation, I will earn the equivalent of 0.30 USD. Digging a hole in the US will enable me to go the movies, get popcorn, and a beer later to boot. Digging a hole in a poorer nation might get me a cheap meal. The American coming to the poorer country with 30 USD will be able to do even more. How is this possible, when a hole in the US is the same as a hole in a different country, and used for the same purpose? | Economics | explainlikeimfive | {
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"Different locations have different infrastructure and living expectations so the living costs are quite different. This also creates a feedback loop where things gets more expensive because the living costs are more expensive. In the end it is not money you want but the goods and services that the money provides. As an example a $300k a year job in Nowhere, Nebraska is a pretty good paying job as you can afford a big house. The average pay is low as land and food is easy to come by so you can pay for a lot of things because the people you pay does not need much money to live, etc. However a $300k job in NYC is quite low. Houses are expensive and it requires a lot of logistics to get food and other goods into the city. And the barrister who made your coffee have to get as much pay to not go bankrupt. The prices is also inflated by people moving to the city and people who make a lot of money in the city and can afford to pay people a lot of money.",
"Digging is non-tradeable. You expect something like salt or car tires to be close in value across borders, minus wholesale/retail margins and taxes/tariffs. But something like a dentist's appointment is nontradeable. Unskilled labor that doesn't end up in a traceable good too. This is why economists have been fixated on open borders: we generally agree that free trade in goods is the best thing for everyone, but it leaves nontradeable sectors holding the bag. Unless the digger can cross borders and dig where it pays better, of course."
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73zjyh | What exactly does seeding a torrent do? | Other | explainlikeimfive | {
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"When downloading a torrent, you don't receive the data from a single server like browser downloads. Instead, each peer with a copy of the file (even a partial copy) sends you data. That's what seeding is: sending the data you already have to peers downloading the file.",
"A seed is a participant in a torrent who already has the entire file but still stays connected and uploading. The person who starts the torrent is the original seed, but later there can be more than one seed, and the original one can disconnect without leaving anyone with an incomplete download. As lone as one seed stays connected, it is certain everyone will eventually complete the download. The main innovation of BitTorrent was that everyone who downloads at the same time is uploading parts he has already finished downloading to other people, so that the total available download speed is much faster than what the original seed has available. But seeds are still very important because the ensure that the entire file can be downloaded. If all seeds disappear from a torrent, there is a chance that some parts of the file have not yet been downloaded by any of the others, so that eventually everyone will have the entire rest of the file but still miss those parts."
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73zxp1 | Why does buying stuff (non-essential) make us happy? | Biology | explainlikeimfive | {
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"It depends on what kind of stuff you're buying, but essentially, it's because products are advertised as lifestyle components rather than things. E.G. You're not buying a Mercedes Benz, you're prestigious and the envy of others. You're not buying Prada sunglasses, you're chic and classy. You're not buying TOMS shoes, you're saving the world. Of course, this is a pretty empty, fleeting happiness. Partly because manufacturers need to keep selling stuff, and advertise how much better their latest and greatest products are (even if they are functionally the same as the old ones). But also because of ingrained human nature--if we were permanently happy from any one thing or things, we would have stagnated as a species. Relevant LifeHack--*If* you're going to spend money pursuing happiness, spend on experiences, not things: URL_0"
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7401r0 | What chemical reactions happen when you start fearing for your life? | In the wake of Sunday night's great tragedy, there has been much discussion about experiences of war and experiences of being in a maximum intensity situation. This morning (and yesterday) on my commute, there was a discussion on NPR with a few guys who have had formal military training describing how it felt be thrust into a war-like situation during the event. I am just wondering what exactly gets pushed through the blood stream...is it just adrenaline? One man described it as anger, fear, mania all in one but it mainly ends in pure anger. Obviously some handle this better than others, as with PTSD, some just can't "shake it". There were accounts of several people triggering their PTSD. Does it have to do with the release of certain chemicals in the body and the mental reaction and fear of facing that again? Another man described 'being shot at' the absolute **worst feeling in the world**, and while having no experience with, I can wholeheartedly agree with. What happens in your body and mind when you realize you are in a life-threatening situation? I ask because it seems some people handle it better than others and I'm simply just interested. One man spoke about the situation in such stern, and emotionless detail, yet what he was describing was pure chaos, hysteria, and horror. I know after viewing some of the first-hand videos of the horrific event, I felt an uneasy, on-edge body feeling. It felt as if I was under the same situation and some feelings just uncontrollably happen. I know something sinister was running through my veins because it took a moment for those feelings to subside. | Biology | explainlikeimfive | {
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"Yeah, we don't really have any idea. The connection between brain/metabolic chemistry and emotions is dimly understood, *at best*. Both between individuals and for any single individual, there's no clear and repeatable indication that *this* chemical produces/is associated with *this* emotion, while *that* chemical produces/is associated with *that* emotion. Two people exposed to the same situation could react very differently. A single person exposed to two different but substantially similar situations several weeks or months apart could react very differently in each. And that's just speaking in really general correlation terms. We have no idea whatsoever about the *causation* issues here. As in, does this chemical *cause* this emotion, or is this chemical caused *by* this emotion? Could be either, both, or neither! So yes, there's a general consensus that adrenaline and related hormones are usually released in stressful situations. But connecting those with emotions really isn't something we can do."
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7412i0 | Why do we tend to "like" negative news/information more than positive one? | Other | explainlikeimfive | {
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"Positive things happening are far more common, so people think they're boring. Once you've seen an airplane land, then you feel like you've seen a million. So a headline that says \"100000 AIRPLANES LAND SAFELY TODAY: Skilled pilots brave varied weather conditions and irritated passengers!\" doesn't sound very interesting compared to \"PASSENGER AIRLINER FLIES INTO THE SIDE OF MOUNT EREBUS: Many feared dead!\" It's something innate in the human experience to desire to put things into a narrative context. We like stories. When something scary or negative happens, we instinctively hook onto it like it's the start to a grim novel, despite the fact that it's actually our waking reality. (That sounds horribly depressing (and it is) but this is why there needs to be a great drive in yourself to find how to help, and find people who want to help.)",
"It preys on our subconscious systems that we depend on for survival. We read it because we think it will do something to ensure our survival if we were put in a similar situation.",
"We don't \"like it\" but it sells more, good things can happen all the time but people won't go out of their way to see it, negative events get more attention because people want to be aware of what dangers can threaten their lives, e.g. bombings, mass shootings, car accidents, etc. and because people seek that kind of news it sells better, the news station get more views and more money so that all they show."
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7414mj | Voices usually sound tired early in the morning. What's the best way to "wake up" our voices quickly? | Biology | explainlikeimfive | {
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"Vocal chords, much like muscles, need to be warmed up to be used at max efficiency. As a singer, every morning I do vocal warm-up exercises to make sure I'm not destroying my voice when I sing. I also work at a call center, so preparing my voice for the day makes it much more manageable to speak on the phone for hours on a daily basis. However, to more directly answer your question, there isn't a \"trick\" that will wake up your voice immediately. Doing some quick exercises can help your voice warm up more quickly, though. There are a lot of YouTube videos on these, but my favorite are \"bubbles\". I would provide links but I'm at work and on mobile.",
"So I'm not sure there is a scientific way, but I'd say practice makes perfect, i tended to be late for things from time to time and get calls like \"where are you, are you still in bed?\" Kind of stuff. So before you answer the phone, Start off with a low growl and then raise it till you have kind of a shout. This should clear any flem and give your vocals a nice stretch. Secondly practice a \"retail\" voice, sharpness and clarity is key. And lazyness that's the driving factor behind it all!!"
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7417xd | Why are animals with slightly different genetic traits considered separate species but humans with slightly different genetic traits are not? | Definitely not implying that any group of people are more human than any other. | Biology | explainlikeimfive | {
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"The general test is do they normally interbreed in the wild in a way that results in offspring that are health enough to breed in turn. If they do, species, if not 2 species. Human can all interbreed, so all the same species. And our genetic diversity is shockingly small compared to most species dues or a fairly recent evolutionary bottleneck. ONe of the reasons racism is stupid. An average family group of chimps had more generic diversity than all of the human race.",
"Animals with slightly different genetic traits are not automatically considered separate species. All different dog breeds have slightly different genetic traits and they are still all dogs. Same with cats or horses. Humans have slightly different genetic traits across different population, yes. These are not different enough to consider them different species though based on the many different things biologists take into account when determining what population is a different species (which includes things like genetics, morphology, diet, spread, willingness/ability to create offspring etc)",
"Species is a fuzzy term. Beyond that, the genetic differences within humans are not easily bundled up into race. For instance, when we think of 'races' in context of humans, we tend to base these on superficial characteristics. What color is the skin, is probably the major one for many of us. But as an example, within a group of people we'd easily consider 'black,' there can be more variation than there is between a person we consider black and a person we consider white. That is to say, you can easily find people between races that are more genetically similar than you might find *within* a particular race. Consider, for instance, that in the US, many people of mixed parentage will be automatically considered black if their skin is visibly a mix of white and black characteristics. Yet they share half their DNA with a white parent. So really, we don't have any divisions, in humans, that are particularly striking that would lead us to see different species. Beyond that, however, and when you look at nature itself, \"species\" is...well it's kind of broken. A lot of people will say \"it's a different species if it cannot interbreed successfully. But that's not really accurate. There are animals of the *same* species that cannot interbreed. There are animals of the *same* species that can interbreed with some of the rest of their species, but not all of the rest of their species. There are *many* animals of different species that can interbreed, some of which can themselves reproduce. And there is an entire kingdom that doesn't have sex in the first place. Differences exist on a continum, unless you are a clone, you are a bit different from another of your species. You're a bit more different than our ancestor species from which humans descended. Yet at no single point would we say \"This is when the first human was born.\" Instead, each offspring was a bit different from its parent. We define separate species as a somewhat arbitrary point along the way of \"a little different\" that we determine is \"Different enough,\" often after the fact, when we see the accumulated differences of millennia.",
"Because they are not the same \"slightly\". A brown bear and a polar bear might seem as \"slightly\" different as an African and a Caucasian, but they the is a much great genetic gap between the bears. They diverged about 4 million years ago, whereas humans only broke off from the main line when they left Africa maybe 50,000 years ago. The human populations also continued to intermix in that time, especially as transportation technology improved. The last ancestor of all living humans may have lived as recently as 3000 years ago."
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741tb5 | Why do we routinely screen for some cancers (e.g. colon, breast) and not others (e.g. stomach, brain, etc.)? | Biology | explainlikeimfive | {
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"Putting it bluntly, in some cases screening pays off (in terms of money spent and how much lives you save) and in other cases it doesn't. Whether a screening program is set up often depends on several factors, such as: - How easy is it to screen for that particular type of cancer? The easier / more accessible the screening process, the more likely it will occur. Some cancers are harder to detect than others, so the only way to test whether someone has them or not is with an invasive or expensive test or biopsy. Meanwhile something like cervical cancer can be screened for with a little five minute procedure that doesn't really affect the person undergoing it. - How common is this particular cancer? The more common a cancer is, the more likely a screening will be set up. If you have a type of cancer that maybe 100 people a year get, it just isn't worth the huge costs of setting up a screening program for your entire population. - How much does early detection matter? With some cancers, it really matters whether you catch them in an earlier stage in terms of treatment. Sadly with some other cancer / diseases, prognosis is so bad that even if you catch it early, it is pretty much impossible to fight.",
"Certain cancers are far more common, particularly given certain factors like age, gender, and family history. Many of these common cancers are also fairly asymptomatic until they get to the point where they are much more dangerous/difficult to treat",
"Because certain cancers (Colorectal, breast, some types of skin cancers) are somewhat common so they are often looked for. In addition, certain habits increases the likelihood of others (smoking = lung cancers, drinking = some types of liver cancers, etc.) so they are looked for when it is disclosed to a health professional that you have these habits. Could also depend on genetics (EGFR mutations, BRCA genes, etc.). Essentially, a HCP needs a \"probable cause\" to look for something; if I was to be screened for every cancer whenever I did a small health checkup, it would be a massive waste of resources. You need to keep it economically sane (from a client and provider perspective). EDIT: added \"certain\" that I left out!"
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7426ws | When does mutation mean that there is a new species? | People all over the world have adapted to their surroundings with visible mutations as long as we've been keeping track. We've adapted at the genetic level to pretty much everywhere that we can reach. Sherpas are adapted to elevation. Inuit are adapted to cold. When do those mutations add up to a new species? | Biology | explainlikeimfive | {
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"So say a population of birds goes off and splits in two, through some random environmental means such as a major storm pushes them into unfamiliar but beneficial territory, or the group just wanders off. Those two isolated groups will then interbreed amongst themselves, and their respective gene pools will tilt toward one prediction or other. Eventually, through all this interbreeding and mutation etc, those two bird populations, originally of the same species, are now separate species. This means they can no longer produce viable offspring, or if they can produce living offspring, said offspring cannot produce viable/living offspring of their own. This is known as a post-zygotic isolation. Pre-zygotic isolation is when the group(s) somehow diverge in habitat, behavior, temporal and mechanical parts/traits. There is also gametic isolation patterns that can come into play here. Generally this means that the birds can no longer inhabit the same area of space, their mating signals differ slightly enough to discourage interbreeding, they wake/sleep/mate at different times, and their genitalia are no longer compatible. Any of these isolations can create speciation within a group over a period of time. Speciation can occur in a group that is split as well as a geographically identical population. Any manner of these pre-zygotic (before mating period) isolation factors can occur in either of these instances. Sorry if not clear, on mobile. Edit: wow guys I'm glad this got the discussion flowing! So I'm still on mobile, and I am currently a passenger in a car and I get sick if I look down too long, plus I have to go to school early in the morning. SO, if anyone feels like answering the comments or whatever then feel free, I'm far from an expert. I'm actually attending school for a BA in Biology so that's how I managed to answer this very fundamental question. That being said, any flaws in my logic, please feel free to correct them! Sources would be very helpful for things like case studies, as I find this really interesting and would love to learn more about this subject! I'll try to get some more info from my professor tomorrow if you guys would like, so yeah! Thank you for this question to OP and thank you for all the additional information! Edit: Wow so this really blew up over night... I guess to summarize, one species can become two or more through various processes such as geological splitting and behavioral differences, and this happens over a long period of time, and is not a concrete explanation, as many have felt free to point out. I guess if you want a better answer then you can check out the evolutionary biologist's comment thread. Again, NONE OF THIS IS CONCRETE, just a single explanation in a sea of multiple explanations to similar sets of questions. This is also what I learned in class, and again I am not an expert. This is also ELI5, not Scientific Discourse 410. I know my explanation was a bit more complicated than what one would tell a 5 year old (not that I would know, I don't talk to kids much anyway), but it's the simplest I could make it while typing it out on a tiny screen on an hour drive and trying to get as much relevant information as possible out there. All that being said, I think this will be the end for me here. Just wanted to say that I acknowledge defeat, and I look forward to continuing to read what you all have to say. Thank you for all your replies! It'll be slow going, but I'll try to read them all!",
"Kinda late here but as an evolutionary biologist I thought I would add my input. The question you are asking is essentially: When are 2 living beings different enough to be considered different species? The short, and frustrating, answer is there is no one definitive way. Makes sense though, the natural world doesn't act in absolutes, but we as humans like to. I'll explain how we do it, but first let me ask you a question to think about: When does red become orange on the color spectrum? Surely it does as anyone would agree, but exactly where? Tough to say. Depends on who's looking, who you're asking, how you define red and orange. Lots of different things come in to play. Anyway. The most agreed upon way is that if 2 animals can reproduce and have a viable AND fertile offspring, then they are the same. Otherwise they are different. Viable = able to live. Fertile = able to reproduce. So, for instance, if a human and a horse attempt to reproduce, they would have an inviable (and therefore infertile) offspring. So they are different species. If a Donkey and a Horse reproduce they actually have a viable offspring. A mule. However, a mule is not fertile, so therefore cannot reproduce, so we call horses and donkeys different species. And finally, if 2 horses reproduce they have a viable and fertile offspring and are therefore considered the same species. This is why ALL dogs are considered the same species according to a biologist, despite the remarkable differences between a chihuahua and a Great Dane. HOWEVER, there are exceptions to this. One example is in Giraffes. There are considered to be a handful of different species of giraffes in Africa (5 or 6, can't exactly remember). But the only difference between them are subtle differences in the patterns of spots in their hide. If and individual of one species got together with an individual of another and decided to reproduce they would produce a viable and fertile offspring. So why don't we say there is one one species of giraffe in Africa, similar to dogs? Because, as far as we can tell, these different species NEVER reproduce with each other naturally. They all mind there own business, have their own territories and are all separate from each other, so we go ahead and say they are different species. Similar exceptions can be found all over the world. And of course it gets much more complicated when we start trying to differentiate between single-cell organisms/bacteria/viruses especially are very odd and full of exceptions to our rules. Anyway, hope this helps! Speciation is the term you should do research on if you want more info. It's actually a very interesting area of evolution and is often overlooked!",
"Here's an analogy. There is a [color gradient]( URL_0 ) that starts green, then every pixel, becomes slightly more red. Between every 1, 2, or even 10 pixels, there is no noticable color change. However, if you look at the colors between 10,000 pixels, there is a change. So where is this \"line\" between green and red drawn? Well, you can't draw a line. There is no distinguishable boundary between the two colors. Let's pretend that the green color is the predecessor to the horse, and the red a horse. Every pixel represents a generation. Each generation is essentially exactly alike to its offspring and its parents. Yet over time, there is change. When talking about species, the term almost abitrary. Although horses and donkeys are considered different species, 100,000 years ago, they were the same. They would produce fertile offspring 100% of the time. Then 90,000 years ago, they were 90% likely to produce fertile offspring, so on and so forth. Even today, there is a small chance that a donkey and a horse can produce a fertile offspring. When is the line drawn? As you can see, it's is quite tough to categorize species, especially when looking at them in such a micro point of view. tl dr there is no one clear \"line\" that separates 2 species. Instead, think of evolution as a gradient, where over hundreds or even thousands of generations there is change, but no clear cut single point.",
"The shortest answer is a new species occurs when it can no longer breed with the old species. Whether that reason is genetic, behavioral, or isolation.",
"From Richard Dawkins' *The Tyranny of the Discontinuous Mind*: > If a time machine could serve up to you your 200 million greats grandfather, you would eat him with sauce tartare and a slice of lemon. He was a fish. Yet you are connected to him by an unbroken line of intermediate ancestors, every one of whom belonged to the same species as its parents and its children. > “I’ve danced with a man who’s danced with a girl, who’s danced with the Prince of Wales”, as the song goes. I could mate with a woman, who could mate with a man, who could mate with a woman who . . . after a sufficient number of steps into the past . . . could mate with ancestral fish, and produce fertile offspring. To invoke our time machine again, you probably could not mate with Australopithecus (at least not produce fertile offspring) but you are connected to Australopithecus by an unbroken chain of intermediates who could interbreed with their neighbours in the chain every step of the way. And the chain goes on backwards, unbroken, to that Devonian fish and beyond. On the way, about six million years into the past, we would encounter the ancestor we share with modern chimpanzees. It so happens that the intermediates, like the common ancestor itself, are all extinct. But for that (perhaps fortunate) fact, we would be connected to modern chimpanzees by an unbroken chain of intermarrying links. Not just intermarrying but interbreeding – producing fertile offspring. There would be no clear separation between Homo sapiens and Pan troglodytes. The only way to maintain our human-privileging laws and morals would be to set up courts to decide whether particular individuals could ‘pass for human’, like the ludicrous courts with which apartheid South Africa decided who could ‘pass for white’. > And of course the argument extends to any pair of species you care to name. But for the extinction of the intermediates which connect humans to the ancestor we share with pigs (it pursued its shrew-like existence 85 million years ago in the shadow of the dinosaurs), and but for the extinction of the intermediates that connect the same ancestor to modern pigs, there would be no clear separation between Homo sapiens and Sus scrofa. You could breed with X who could breed with Y who could breed with ( . . . fill in several thousand intermediates . . .) who could produce fertile offspring by mating with a sow. > Humans are clearly separable from chimpanzees and pigs and fish and lemons only because the intermediates that would otherwise link them in interbreeding chains happen to be extinct. This is not to deny that we are different from other species. We certainly are different and the differences are important – important enough to justify eating them (vegetables are our cousins too). But it is a reason for scepticism of any philosophy or theology (or morality or jurisprudence or politics) that treats humanness, or personhood, as some kind of essentialist absolute, which you either definitely have or definitely don’t have. If your theology tells you that humans should receive special respect and moral privilege as the only species that possesses a soul, you have to face up to the awkward question of when, in human evolution, the first ensouled baby was born. Was it when the first Homo sapiens baby was born to parents belonging to whatever species is considered to be our immediate predecessor (erectus, ergaster, heidelbergensis, rhodesiensis, no matter, the argument stands regardless)? There was no such baby! There never was a ‘first’ Homo sapiens. It is only the discontinuous mind that insists on drawing a hard and fast line between a species and the ancestral species that birthed it. Evolutionary change is gradual: there never was a line, never a line between any species and its evolutionary precursor. You can read the entire paper with a Google search.",
"The usual standard is that something is a new species if the two populations either (1) cannot usually produce fertile offspring or (2) do not normally mate in nature even when in the same location.",
"The idea that one day an individual with a mutation is born and *bam*, new species is incorrect. Speciation is the result of genetic drift, mutations can contribute to that, but they are not the only or even the primary mechanism. The speciation process begins when a population is separated, either by geography or behavior. Over time, their gene pools drift into different directions, depending on evolutionary pressures and random chance. Eventually, they drift far enough they are no longer likely to breed and become separate species.",
"You've gotten a bunch of answers, a lot of them touch upon most of the issues. But let me summarize first your question: What you are really asking is: > at what point are two different animals/groups different 'species' and how much mutation does it take before that happens? The problem with your question is that it's really unanswerable. The main reason is because you are asking when an objectively measurable event (i.e. mutation in a species/group) eventually equals an very subjective difference, i.e. different 'species' (see u/henzhou [comment for the best explanation of this]( URL_0 )). The reason it's a very subjective definition (aside from the fact that there are many disagreements within science community) is that for *every* definition of \"species\" there are example that directly contradict those definition. You can see this weird problem when you compare two examples: Lions & Tigers are considered by many to be different species. And it's easy to see why. But they can mate, have offspring (Ligers), who are in fact fertile (i.e. 'viable'). So what makes them different species? It's mostly a cosmetic difference between them. Now compare them to domesticated dogs. If you looked at [St. Bernards and compare them to Chihuahuas]( URL_1 ), you'd think they would be different species? Nope. So why are Tigers & Lions different species but Chihuahuas & St. Bernards the same species? Because it's completely subjective. **TL;DR** So then it's impossible to say when mutation have led to 'different species' because it's impossible to say, with clarity, what one means by 'different species'.",
"Really, the definition of \"species\" is really blurry. We classify something as an species when we decide it's useful to. The concept of cleanly defined species is more of a projection than an observation.",
"This is a somewhat sarcastic sounding answers but technically \"never\". Speciation is not well defined and scientists often argue over whether two organisms are different species or not. However, in common practice r/mmmmwhatchasay has the best answer. The thing about genetics is, there is no such thing as \"species\". We are all just variations of the same organism. We are all descended from the same progenitor organism, which itself is probably descended from simple but natural chemical reactions. People talk about sex as a spectrum, autism as a spectrum, light as a spectrum. In many ways genetics is just a spectrum of related individuals. Individuals at the ends of the spectrum appear quite different while individuals close together in the spectrum appear similar. A species is therefore a selection of individuals that are close on this spectrum. How close? That's pretty much arbitrary and no one can seem to agree. Now, back to smoking up with my relative Mary Jane ;)",
"Hi OP. I have only a few minutes, so forgive me if the response is brief. I'm an evolutionary biologist, as some others in this thread seem to be as well. You have a few decent answers; (1) /u/mmmmwhatchasaayy has done a good job explaining broad processes, but they didn't really answer the question, i.e. 'when does mutation mean that there is a new species'. The question itself is missing a difficult concept, which #2 addresses well. (2) /u/audi_fanatic did a nice job of explaining, essentially, that there isn't really a point at which we can say: 'these two things are different species'. Same goes for /u/faithfuljohn and perhaps others that I missed. Basically, delimiting species (i.e. determining when two things are different enough to be considered species) is a huge grey area, most of the time, and species limits are often arbitrary in a sense. We don't really have an objective , totally agreed-upon way to determine species. This response talked about the **biological species concept** (breeding, fertile offspring, etc.) which is a fairly common viewpoint developed in the '40's* by Ernst Mayr. (3) Really, the only time (I would say) that you can directly point to a single mutation and say 'this is when these two organisms are separate species' is when the mutation directly influences the reproductive capabilities between the organisms in question. For example, if there is a mutation in a snail that changes the spirality of its shell such that it can no longer mate with snails with a different shell spirality, then that mutation has caused reproductive isolation between the two organisms (much to what the biological species concept alludes to). If organisms can't interbreed, they can't exchange genes, and therefore they should be considered separate. It's important to note that there are many instances in which a single mutation could cause reproductive isolation, but also that most of the time this is the result of many mutations, rather than just a single one. Further, it could happen in many different ways (e.g. chromosomal inversion); so long as the mutation resulted in the lack of gene flow between newly formed species, then it works as an isolating mechanism via mutation. The idea of lacking gene flow also can be traced back to a guy named Kevin de Queiroz, who came up with the **independent lineages** species concept. Essentially, organisms that have been separated (by whatever means) for long enough that they can be considered to be evolving independently should be considered separate species. Hopefully this all makes things a little clearer. EDIT: Mayr's work on the [biological species concept]( URL_0 ) is mostly attributed to his work in the 40's, particularly in his 1942 publication: *Systematics and the origin of species from the viewpoint of a zoologist.*",
"Imagine you're on the iPhone team. You're working on some changes to the iPhone. How many changes does it take before it's a new version and not just a hardware revision? If you move one internal screw a millimeter to the left to improve heat distribution, are you going to call the result the new iPhone 12, or is it still the iPhone 11? How many changes does it take before it's a new product entirely and you decide to call it something other than an iPhone? How much do you have to change it before it's not really a \"phone\" anymore? There isn't an objective answer. Ultimately, you decide on whatever's useful in the context you care about. And since we care about more than one thing, you see different metrics in different contexts where we care about different things. A repair technician might care about hardware revision numbers. A customer might only care about larger external changes and major iPhone releases. A developer might care about iOS version numbers in a way that customers might not. When someone says \"what version is the phone?\" the answer depends on what they care about. What trips people up about situations like this is that you can make objective metrics. You can make a metric with an iron-clad rule. You can decide that anything with at least one generation of backwards compatibility is the same version, and that's objective. The trick is that there's just no objective, universal way to *decide on that metric*, even if the metric is itself objective. Maybe what you care about is backwards compatibility. If the connector doesn't fit the port on the old model, it's a new version. But just because the connector is backwards compatible, maybe we still want to draw a distinction based on behavioral differences, and we don't really care that the hardware is backwards compatible because the internals all work totally differently, and it's more important that developers realize that. What if the new connector fits the old port, but it charges and transfers data really slowly because of the mismatch? What if every version of the hardware is backwards-compatible, but only with the very last model before it? What if after five iPhones like that, the next one goes back to the *original* connector, so compatibility forms a ring? If we make iPhones locked to Japanese and iPhones locked to English, do we want to say that they're the same phone, or the same version of the phone? What if they can interoperate? There's no \"correct\" answer. All we're doing is categorizing things, and there are a lot of ways to categorize things, and any categorization scheme you come up with will probably result in some things being hard to categorize. People in this thread are saying that this is an unusual property of species, but actually you see this situation *all over the place* in science. If you look at something as familiar as \"words\" closely enough, you discover there's no obvious objective definition of a \"word\", and any definition you come up with has some cases that are hard to categorize, and you end up with the same situation with different metrics that are useful in different contexts: \"phonological word\", \"morphological word\", \"syntactic word\". Or look at dialects - where does one end and another begin? How do you decide on discrete dialects when they actually transition pretty smoothly over geographical areas? Standard German and Standard French are definitely different, and not really mutually intelligible, and we probably want a way to talk about that, but at the same time there's no discrete border between the languages, but rather a relatively smooth transition between them over the geographic area separating them. This kind of thing is not the exception, it's the norm.",
"The standard guideline that is used practically by biologists is that if two organisms show more than 2% difference in DNA sequence, they are different species.",
"Regardless of the slight changes between humans living in different climates, they still can all have offspring with each other. The only way to create a new species of humans would probably be to isolate them for hundreds of thousands of years - possibly on different planets.",
"The idea of distinct species is something that Richard Dawkins calls \"essentialism\". He calls essentialism a \"plague\", and an idea that is \"...scientifically confused and morally pernicious. It needs to be retired\". Essentialism (still quoting Dawkins) is evidence of \"the tyranny of the discontinuous mind\". So, asking when mutations become species seems to be a dangerous undertaking, like spreading the plague.",
"Species are actually pretty much an arbitrary distinction. There are things which we consider to be separate species which can interbreed, and things which we don't consider to be separate species which can't. Indeed, asexual creatures - things like bacteria - pretty much screw over all reasonable species definitions. [There is no one single definition of a species.]( URL_0 ) Realistically speaking, it is pretty much \"whenever we consider a population group to be genetically distinct/isolated enough/unique enough to call it a separate species\". The biggest problem with calling human groups separate species is that they aren't isolated from each other genetically and there is constant gene flow between them.",
"The short answer is that there is no widely-agreed-upon criteria by which we differentiate species from sub-species from simple regional variants. Biologists frequently disagree on the issue and how it is resolved tends to vary with regard to the specifics. My old dendrology professor --granted this was nearly 30 years ago-- used to say that one man's \"discovery\" was another man's regional variation. Granted, he was concerned with botanical classification which tends to be far less controversial among the general public, where the general public cares at all. As for where anatomically modern homo sapiens (AMHS) is concerned, the truth is that despite what you may think, we are genetically a very homogeneous species. There is nothing in the variation among AMHS that approaches anything even remotely approaching what biologists would consider to be speciation.",
"You're operating under a significant misapprehension about the mechanisms of natural selection and evolution. Mutations actually play significantly less role in speciation than is commonly believed. Genetic drift, and natural selection acting on existing genetic variation are the prime movers of evolution. Mutation introduces new variations, but those variations are almost always deleterious and seldom lead to viable offspring. Successful mutations happen, but rarely. Genetic drift acts on the variation that is already present in populations. For example, it's not that some humans possess a mutated gene that controls cold sensitivity. Instead, natural selection acting on an existing cold-tolerance trait present in all human populations. Those in cold environments with a cold-tolerance trait were generally more successful, had more offspring, and those offspring who inherited that trait were in turn more successful and had more offspring. The generally agreed upon biological species concept is that two populations have become difference species when they are reproductively isolated-either sexually, behaviorally, or geographically. If individuals from two separate populations can reproduce and produce viable offspring, they're not different species."
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74280o | Why is it safe to eat veggies/fruit grown in rain water/waste water - but not drink the water by itself? | Biology | explainlikeimfive | {
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"This is absolutely not always true! Plants can *and do* absorb toxins from their environment. Now, the plant may filter some (or even all) of them out, but it might not. Some might end up in the parts of the plant you eat - **especially** if you eat the roots.",
"Rain water and waste water can contain harmful chemicals if you drink it directly. Soil can filter some of those chemicals by adsorption, later on plants can filter even more. But, not all soils and plants have the same filtering properties. For example, some plants can absorb heavy metals and arrest them in nodules in their roots, you wouldn't want to eat that plant. In general, unless you're close to a contaminated area, the filtering provided by the soil and the plant is enough, meaning the plant is safe to eat. That is without considering the chemical and physical defenses plants make to fend off herbivores.",
"My husband works for a waste water treatment plant that sends reclaimed water to near by dairy's and vineyards the state (I think, maybe the city) has set standards for how this water can be used in agriculture based on how many dyes removed from the end product the water is used. Example: the water can be used to irrigated crops that the cows eat, that then get slaughtered for market because it's enough steps away from human consumption but they cannot use the water for the cows to drink. Also it can be used to water the vineyards because the grapes go through a fermentation process before consumption so that gets counted as an extra step. It's all very regulated for water that under analysis would be as clean as your tap water if it was chlorinated.",
"I have a degree in a waste water related field, DO NOT eat fruit/vegetables grown in any type of waste water. Some popular science articles may speculate that plants have the ability to filter anything, but water soluble toxins may not be removed from the water which is absorbed by the plant.",
"What you don't want from random waste water is mostly harmful bacteria. These can't survive inside a healthy plant, and physically can't get into it because the water absorbing root's openings are smaller than the bacteria.",
"When I was younger we were always told not to pick blackberries and blueberries that grew on the highways because they would have higher levels of toxic chemicals from absorbing the car exhaust. Yes that would be another explain like it's 5 question.",
"You totally can drink rain water, you just have to make sure you've collected it in a way that won't contaminate it, or you'll need to filter it after collection.",
"1. Rain water should be relatively pure water. It will have some low level atmospheric contaminants in it, but overall is actually pretty clean. 2. Waste water is a vague and non-specific term. If you are talking about treated wastewater after the processing is done, that is alos relatively free of contaminants. 3. Wastewater in the form of runoff and storm drain water may or may not have large amounts of contaminants in it based on where the runoff is from. The reasons you can eat the food and not drink the water are: You may actually be able to drink that water in the first place. We generally don't becasue it *could* contain contaminants that will sicken you. The other reason we don't drink that water is that it is unappetizing to most people. There are water sources that are absolutely not contaminated by anything that would cause health issues that look and taste horrible. The other thing is that for many biological contaminants the plant is not a host or a carrier of the contamination. The water may put bacterial or viral spores and organisms onto the plants, but the plants aren't infected and don't carry the organism inside the produce. Now here is a key point, always wash your produce. There may be pesticides, contamination, dirt, fumigants, or even in some cases food wax coatings on them. Not good eats. The last thing is, well, we do get sick. There are several cases of heavily water using crops such as lettuce that have carried e. coli contamination introduced in the field via workers defecating in the field or bad water that the plant actually pulled live e.coli up through its vascular system into the plant and caused outbreaks. So simple answer. 1. The water may not actually make you sick in the first place and second people do occasionally get sick from contaminated water used in irrigation.",
"boy i hope you're abiding by that idea. you're going to get sick. rainwater isn't always clean, ever wonder why its so clear after a heavy rain, all the particles that used to be in the air are now gone thanks to rain catching them, if you're in a polluted area that rain is now contaminated. we had some bushfire reductions burns close, the air was filled with haze. heavy rain overnight and my car is filthy but haze has gone. that gunk is in ppls water tanks as well now. you will also find that regulations regarding fruit and veg have some strict guidelines about what source is used to water plants. they found a strawberry farm in my town was using waste from a septic tank as fertilizer, the only reason they looked was a spike in ppl turning up in the hospital sick. grey water is only recommended for lawns etc, not produce plants and even then there are guidelines as to how far away systems should be to plants that produce fruit as well because of contamination."
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74281g | How do so many different games have GOTY editions? | Other | explainlikeimfive | {
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"Because they are pretty meaningless... Some noname magazine/website declares a game \"game of the year\", often in really niche categories (Action game of the year, Shooter of the year... Battlefield of the year), and because of that they call themselves \"game of the year 2015\" and use it for marketing.",
"It's because Video Games don't have a unified award system or even 2-3 industry respected awards. Instead if ANY publication names you Game of the Year you can put GOTY on your box. Really all it means these days is \"Edition that includes all DLC.\" This is why you also have funny situations where The Last of Us can win over 200 Game of the Year Awards.",
"There are many different categories for GOTY, and many different media outlets that issue GOTY awards. If the New Zealand Game Review says you are the best Indie Multiplayer Horror Themed First Person Shooter of 2017, you get to call yourself GOTY."
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7429i5 | Why does something having no face/minimal features make it cute? | I know the concept of what's 'cute' varies from person to person, but there are certain things in this example that are almost universal. There are classic character designs like Hello Kitty and Marvin the Martian who have no mouths, but are considered adorable. The Valais Blacknose sheep has such dark facial fur that you can't really see its features, but it often gets referred to as 'world's cutest sheep' (and honestly, agreed). Shouldn't something that looks as if it has a gaping void in its face be inherently disturbing? Why is there such a fine line between endearing and unsettling here? | Other | explainlikeimfive | {
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"Our brains are engineered to think human babies are cute so that we want to keep them alive. Babies have round faces and small features. A cartoon with minimal features roughly resembles a baby's face.",
"> Ethologist Konrad Lorenz proposed that baby schema ('Kindchenschema') is a set of infantile physical features such as the large head, round face and big eyes that is perceived as cute and motivates caretaking behavior in other individuals, with the evolutionary function of enhancing offspring survival. [Source]( URL_0 ) Not sure about your sheep but I find them neither very cute nor too disturbing. Funfact: the blobfish is now the world's ugliest animal. Poor guy is being taken out of context, since he would look much better in his natural habitat.",
"Scott McCloud does a great job of answering this question in his spectacular (comic) book, *Understanding Comics*. Chapter 2 is the verse that deals with this specifically, and it starts on page 24 of this PDF: URL_0 The gist of it - and McCloud explains it much better than I do - is that you don't have a conscious awareness of your own face as an image. When you see other people you can see all the details of their faces, but you rarely see all the details of your own face - you FEEL them instead. You don't have a sense of detail...you have more of a sense of general placement, just a few key elements - eyes here, eyebrows there, mouth here (neutral, turned up, turned down), etc. When you look at a minimalist, simplified version of a face, what you're seeing is a *visual representation* of that vague awareness of what a face *feels* like. Or as McCloud says, when we look at a photo, we see someone else...but when we look at a cartoon, we see ourselves."
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742dxz | Why can't humans break the N2 molecule but some microorganism can? | Chemistry | explainlikeimfive | {
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"Humans can break the molecular nitrogen bond - the Haber process is used at an industrial scale to produce fertilizer. It takes a lot of energy to do it but it's possible.",
"These microorganisms have special enzymes dedicated to processing N2, which our bodies don't produce. URL_0"
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742ehd | why do some people with depression lose their appetite and not eat much, while others eat more than usual? | Biology | explainlikeimfive | {
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"Depression causes you to feel sad or numb. Eating can give you a feeling of being \"happy\", but it's very short lived. We have a term for it - \"comfort food\". So people eat more, and generally unhealthy food. Or, depression can make you uninterested in normal activities, like eating. It just takes too much effort to make a meal and consume it. I've experienced both.",
"Depression is a really complicated disease. Currently, the prevailing theory for why it occurs is reduced serotonin signaling in your brain. Serotonin signaling is related to mood, but it is also related to things like movement, digestion and appetite, sleep, motivation, memory, and probably a bunch of other stuff as well. A reduction in serotonin signaling can affect any and all of these, and which ones it affects depends on both the magnitude and location in your brain of the reduction. The reason why it can swing either way is really just because our brains are complicated. In some places serotonin signaling can increase a drive (like appetite) and in other areas it can act to decrease that same drive. It's also true that many other types of signaling also affect drives like appetite, and those can also be out of wack. It all really depends on the person and on the brain.",
"Serotonin is probably relation to depression in some way,* and most of the serotonin in your body is in your stomach! Your enteric nervous system, which basically runs the length of your digestive system, is your second brain. It's responsible for a lot of things, including all of the movements that push food through the digestive system. When you feel really upset, your stomach can feel unsettled because it really is moving strangely. If you interpret that feeling as 'sick,' you won't have a lot of drive to put more food in there. If you interpret that feeling as 'hunger,' you'll want to put more food in there. In all likelihood, the explanation is more complicated than that. There is a lot of emerging research around the role of the gut biome in mental illnesses. Depression itself generally makes it hard for people to care for themselves, and things like grocery shopping, preparing meals, eating, cleaning up, etc. can be overwhelming. There are all sorts of disordered eating habits that might come into play, like relying on food for self-soothing/comfort. Depression can be a pit of apathy, so people may not care enough to eat or may not care enough about themselves to eat well. There is probably a little of everything involved. *It's already in this post. The depression-serotonin link is more correlation that causation at this point. There is a bunch of newer research that suggests lower serotonin may be a result of depression, not the cause of depression.",
"Psychotherapist here. It's very similar to why some people develop binge eating disorder and some develop anorexia; the underlying cause is similar but the coping skill is different. The unconscious can either want to bury feelings with food or starve them out in an effort to avoid them.",
"I'll chime in anecdotally as a depressed person who overeats. My eating has ZERO to do with my appetite or the way my stomach feels. It is completely divorced from drives relating to hunger and nutrition. The only reason I might pay attention to the way my body feels about eating is waiting until I feel only full (as opposed to nauseatingly stuffed) before eating again. The motivation to eat is entirely based on the pleasure I get from eating, which seems to be the only thing that gives me pleasure. I know I would be happier if I lost weight, but I would have so much less pleasure in my life.",
"There are several sub-types of depression. Eating more often goes along with atypical depression. Eating less often goes along with melancholic depression. The same goes for sleep, as well. Some people sleep more, some people struggle with insomnia.",
"It can't be ELI5 because even the experts don't know. There are a ton of contradictory symptoms under the umbrella term \"depression\". Symptoms can change dramatically with different depressive episodes with the same individual, too. There are so many metrics involved that it becomes too complicated to account for all the factors. It is also difficult to study ethically. I wrote an undergrad paper on these problems that I'm quite proud of to this day. It was something pretentious like \"The viability of the diathesis-stress model for affective disorders: a meta-analysis\", but damned if it wasn't actually good. Edit: The title was \"The hypothalamic-pituitary-adrenal axis and the viability of the diathesis-stress model of depression\" for a neuroscience course",
"Not attempting an ELI5, but sharing what I learnt from \"*Why Zebras Don't Get Ulcers*\" by Robert Sapolsky. Though the explanation is about sustained stressors (physical or psychological), I believe that medical depression is a ceaseless psychological stressor (based on literature and second-hand experiences with family and friends) and hence, could help shed some light. First, some terminology - People who eat more during stress are called '*Hyperphagic*' while those whose appetite goes for a toss are termed '*Hypophagic*'. **Claim?** Depression can take on a rhythmic nature (less in morning, grows with the day, or reverse). So, the degree of depression varies with time. How often and for how long the coping mechanisms are engaged in the body depends on this. This makes timing critical. If it is a very long bout - it is most likely going to suppress appetite. If it fluctuates rather rapidly, it is more likely to cause people to gorge on food. This might be the case when the person is somehow able to distract himself on to a task that demands concentration. For that while, the body kind of temporarily forgets about the depression and tries to restore the vegetative state. As soon as the task is over, the mind gets back into its low depressive gear and up goes the coping mechanism. The problem is, turning the coping mechanism on is fast, but bringing it back to normal is slow. **The Why?** Hormones released during onset of stressor (CRH) tend to inhibit appetite. The other hormones that are released as a result of these hormones (like Glucocorticoids) tend to stimulate appetite. During the onset, the suppressors outweigh the effect of stimulators. While we are in the middle of it, there is a tussle between the two as both are present in rather large quantities. Depending on which hormone outweighs the other tends to determine if we'll end up hungry or will lose appetite. During the end, recovery of body starts, so it tries to get more energy to do repairs and construction. Thus, inhibitors are removed from circulation in the body, leading to increased appetite. Of course, this isn't completely accurate as there are many variables that determine the outcome. But it is a decent generalization. To quote Sapolsky \"The type of stressor is key to whether the net result is hyper- or hypophagia. Take some crazed, maze-running rat of a human. He sleeps through the alarm clock first thing in the morning, total panic. Calms down when it looks like the commute isn't so bad today, maybe he won't be late for work after all. Gets panicked all over again when the commute then turns awful. Calms down at work when it looks like the boss is away for the day and she didn't notice he was late. Panics all over again when it becomes clear the boss is there and did notice. So it goes throughout the day. And how would that person describe his life? 'I am like, SO stressed, like totally, nonstop stressed, 24/7.' But that's not like totally nonstop stressed. Take a whole body burn. *That's* like totally nonstop stressed, 24/7. What this first person is actually experiencing is frequent *intermittent stressors.*\" And what's going on hormonally in that scenario? Frequent bursts of CRH release throughout the day. As a result of the slow speed at which glucocorticoids are cleared from the circulation, elevated glucocorticoid levels are close to nonstop. Guess who's going to be scarfing up Krispy Kremes all day at work? So a big reason why most of us become hyperphagic during stress is our westernized human capacity to have intermittent psychological stressors throughout the day. Another variable that helps predict hyperphagia or hypophagia during stress is how your body responds to a particular stressor.\" The roots of this may lie in reasons well before you were even conceived. So, that's a long story. Also, hyperphagics don't just eat more but crave a particular type of food - sweets (comfort foods). Glucocorticoids not only stimulate appetite, but appetite of a certain type of food, and also where it is to be stored - abdominal fat. Why? \"...based on some fascinating recent work by Mary Dallman from the University of California at San Francisco: consuming lots of those comfort foods and bulking up on abdominal fat are stress-reducers.\" [Endocrinological changes in hormones during a stressor]: [1] Why Zebras don't get Ulcers by Robert Sapolsky [Rhythmic nature of Depression]: [2] The Depths – The Evolutionary origins of the depression epidemic by Jonathan Rottenberg [3] Darkness Visible by William Styron",
"It involves serotonin and serotonin receptors. 90% of your serotonin is in your gut. Many of the serotonin receptors effect hunger and nausea such as 5-HT3.",
"I have depression, anxiety, and IBS, and they are related. When I have episodes of depression and anxiety, the extra sensitive nerves in my stomach flair up. I often get nausea and diarrhea when I am under stress and it makes me not want to eat. I believe that this is why I am only 100 lbs. It seems to be genetic because my mother has the same issues. She quit her job and went from about 125 lbs to about 110."
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742eyj | How come no bodies have been found of ''cryptids'' such as dragons, sea dragons, werewolves, vampires, fairies, gryphons, elves etc | Biology | explainlikeimfive | {
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"Simple: because none of them exist. For there to be a body of these creatures, they would have to be real."
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742fou | How can vegetables and fruits grown hydroponically contain all the micro-nutrients we need in our diets? | Fruits and vegetables get a lot of their nutrition from the soil. If we start eating them from hydroponic sources, won't we be missing some of these nutrients? ** EDIT ** 1) Do we really know *all* the micronutrients that are needed? 2) Does the economics of sourcing all those micro-nutrients into the solution reverse the economic advantage of hydroponics? | Biology | explainlikeimfive | {
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"they get all of their nutrition from the soil....and hydroponic plants get all of theirs from hydroponic nutrient solutions dissolved in their reservoirs. These solutions, at least the quality ones, contain all the necessary elements necessary for both successful hydroponic growth but also to cover your concerns."
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742kfp | Why is happening psychologically in a murder suicide when the victims are not even people the killer knows? Why would somebody who intends to take their own life want to kill others before doing so? | Biology | explainlikeimfive | {
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"Typically such a person believes he has been treated unjustly by society, so he is striking back at society in general -- which includes basically everyone. URL_0",
"They may believe that they have been mistreated by society as a whole and want revenge, even on strangers. They also may feel like their life was pointless so want to do something that makes them notorious, even in an extremely negative way."
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742xnj | Falconry Experts - What methods do you use to teach a bird of prey to hunt alongside humans? | Other | explainlikeimfive | {
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"We overcome their natural fear of people by teaching them that hanging around us will lead to them getting fed. They are entirely motivated by fear and food. They are not like dogs or even horses or any domestic animal that can develop feelings for you like love or like. They don't like to be pet. They only respond to positive reinforcement, not punishment like dogs. You can't tell a bird of prey \"no!\" They are wild animals. They learn to cooperate with you for food. Eventually they are conditioned to trust a person or people because nothing bad happens when the person is around. The caveat is that even a few days of not interacting with the bird and keeping that association fresh will cause it to revert back to its natural fear of people. There is a lot of nuance, instinct, skill, and experience required on the falconer's part to do this correctly. Check out the California Hawking Club or North American Falconers Association websites for more in depth information or beginner book recommendations if you're interested in learning more. Tl;dr Hunger and patience lead to trust and cooperation, although temporary without regular repetition and reinforcement of the desired behavior.",
"You can't. You just make them tolerant of you and then place them, lean and hungry, so the prey they see is the prey you want. Then you use the fact that they have the attention span of a goldfish to swap out the quarry on them."
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742zjk | How comes people who get concussion or memory loss can remember how to speak but not other things? | They can remember things like how to breathe,speak,walk,etc but can't remember things like their friends and family? | Biology | explainlikeimfive | {
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"Different part of the brain does different tasks. You can damage parts of the brain and therefore get certain abilities reduced. However other functions can still function normally as those parts of the brain is not damaged. A lot of brain injuries can therefore be very strange and might not be immediately noticeable."
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7434gw | What is happening to your body when you become more flexible? | Biology | explainlikeimfive | {
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"1\\. You are literally stretching your muscles and tendons. Imagine a rubber band; as you pull it it stretches and wants to return back to the original state. The more you play around with it, the weaker that force and the more you can pull it apart. Same exact thing happens with muscles. This is the biggest factor and will be the main way most people increase flexibility. The two points below are also a factor but generally don't make much difference unless you're double jointed or a gymnast 2\\. You have special cells that tell your muscles to contract when they are stretched out. This prevents your muscles from being pulled too far and ripping. As you stretch, those cells are trained to allow more give, allowing more flexibility. 3\\. Your joints are surrounded by cartilage and all other sorts of tissue which limit the freedom of movement for the joint. When you stretch these tissues become more elastic, allowing more range of motion for the joint"
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74360x | Why is it easy to hold your pee in overnight but difficult during the day? | How come it is easy for people to hold their pee in whilst sleeping, but during the day it is difficult? Surely your body will be doing more processing of water in your sleep and make you need to pee more. | Biology | explainlikeimfive | {
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"during the day we move more and press on the bladder, gravity draws the urine towards the sphincter with greater force when we stand, and we can actually do something about it so our brain alerts us more to the need.",
"The brain releases a hormone at night that reduces urine production (called vasopressin/ anti-diuretic hormone). So your body makes much less urine at night. Sad fact - this system gets less good as you age and lots of late middle aged folk have to get up to pee in the night."
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7437vg | - Exit numbers and mile markers | I’ve noticed that most of the time exit numbers will match the mile markers on highways, but sometimes they don’t? I’m confused help! | Other | explainlikeimfive | {
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"It varies by state. Some match the exit to a nearby mile marker so you can tell how far away from one another. Other states prefer to number exits consecutively so you know how many more exits you will need to pass (or you can get off at) before your exit. In many cases, there may be exceptions within a state, where one state uses one of those systems except for a highway or two.",
"One interesting effect of highway concurrency( when a newer highway uses the same space as an older one) is that there will be some mile marker duplication where the newer highway will join an older highway at the older highway's marker 100, but the newer marker will be 5. The old one already has a 5 further back. Can make exit numbers confusing. URL_0",
"Historically, exits weren't always numbered (they're not all numbered here in LA) but while the Interstate Highway System was built, it was encouraged in 1961 and then required in 1970 to number exits. California got a waiver since many exits were already built unnumbered. Some states built mile-based exit numbers while many states built sequential exit numbers but that lead to the situation where several exits were built in between two sequential exits so the exits had be renumbered with a letter appended to the number. IIRC, I saw an exit with a G (six exits added after numbering) appended to it in Ohio. This led to states adopting mile-based exit markers starting sometime in the 1970s (Georgia, for example, switched from sequential to mile-based markers starting in 2000). In 2009, the Federal Highway Administration made mile-based exit numbering mandatory and each state had to submit a plan to number their exits using mile-based markers. Due to budget issues, a lot of states haven't been able to stick to their plans and have had to extend the time they need to number their exits (California used to have a plan that would have numbered all exits by 2004 but it hasn't been completed yet and there's no deadline for completion now).",
"Highway exits used to be sequential instead of by mile marker. Near where I live, there's an exit at mile 1, mile 5, mile 8, mile 11, mile 15, and mile 18. Those exits used to be called Exit 1, Exit 2, Exit 3, Exit 4, Exit 5, and Exit 6. Which made sense. But who knew how many miles it was between exits? Now they're called Exit 1, Exit 5, Exit 8... and you know how far apart they are. And they don't go by fractions or decimals, so if there's an exit between mile 2 and mile 3, you have to make a decision, which number do we give it. Etc."
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743fg0 | What is pseudoprime numbers? | Mathematics | explainlikeimfive | {
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"Lets say I have a certain number and I want to know whether it's prime or not. The simplest way to do this is to try dividing the number by every smaller number - if I find a divisor then the number isn't prime, otherwise it is. This is a *deterministic* method - I will know with 100% certainty whether the number is prime or not. The problem with this method is that it's very inefficient. If I have a very large number (hundreds of digits) then this method will take me years, centuries or even millions of years. So people came up with probablistic methods - a test which takes a number and decides with a certain probability whether it's prime or not. One such example is called Fermat's Test, which is based on the Fermat's little theorem: if P is a prime number then A^(P-1) - 1 is divisible by P for every integer A between 1 and P. If P isn't prime then A^(P-1) - 1 might be divisible by P, and it might not be divisible by P. So the test is simple: pick a random number A and check whether A^(P-1) - 1 is divisible by P. If it is then P *might* be prime (we can't know for sure), but if isn't then we know for sure that P isn't prime. This test is efficient, so we can run it with many random values of A, so each successful test will increase the probability that P is prime, and we only need one failure to determine that P isn't prime. There are other such tests, such as the Miller-Rabin primality test. A pseudoprime is a non-prime number that can cheat such a test. Each test has its own set of pseudoprime numbers, for example the numbers that can cheat Fermat's Test (i.e. non-primes for which A^(P-1) - 1 is divisible by P) are known as \"Carmichael Numbers\". They are \"pseudo\" primes because they appear prime, even though they aren't. Some tests, such as the aforementioned Miller-Rabin test, don't have any pseudoprimes."
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743ih7 | How is the observable universe 46.6 billion light years wide if the universe is only 13.7 billion years old? Should we only be able to see 13.7 billion light years away since that's all the light that could possibly reach us in that time? | Physics | explainlikeimfive | {
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"The objects that are now 46.6 billion light years away were not that far away in the past. The light that we see from those objects didn't have to travel 46.6 billion light years. Think of it like me throwing you a ball, and then running further away than I can throw before you catch the ball. It seems like I'm impossibly far away to have thrown you that ball.",
"I'll explain with a specific example. The farthest galaxy we can see is GN-Z11. If we look at it right now and calculate the distance of that galaxy we end up with 13.4 billions light year away. That mean that it took 13.4 billions year for the light to travel from where that galaxy was to where we are now. During that 13.4 billlions year period, that galaxy continued to go away from us and the real distance between us and GN-Z11 is 32 billions light year away. The same with all the observable universe. We can only see 13.7 billions light years away, but the edge of what we can see is 13.7 billions years in the past and so today in reality it's 46.6 billions light years away.",
"13.7 would be the radius of the sphere we can observe, so first we double it to know how wide the observable universe should be. That gives 27.4 billion light years. Next consider that the universe currently is expanding at 78km/s per mega parsec away. URL_0 So accounting for expansion since the beginning of time will give you the other 20 or so billion light years. Edit: Firstly after looking it up: /u/jasoba is right and the observable universe has a diameter of around 90 billion light years. Secondly: after reading this back I realise I could have done a better job of explaining it so here goes take two: We know that the universe is, and has always been expanding. This is a key point because the light we see was emitted when the universe was smaller. To analogise: imagine a distant galaxy as a far away battle. The one of the armies decides that they need to send a runner back to the king to update him on the battle's progress. Once the runner begins his journey, the enemy begins to retreat away from the direction in which the runner is going. This means that once the runner arrives at the king. The king will know about the battle. But because of the battle moving away while the runner was running: the king is able to know about an event that is further away than the distance the messenger was theoretically able to travel in the time he did.",
"Maybe the answers from this post a week ago could help you out. URL_0"
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743pja | Why do apartment buildings use vertical blinds? | Every apartment I've ever lived in has had vertical blinds in the common areas. I've always found them a nuisance and my wife felt the same way about past places she lived before meeting me. Is there a reason they're so common? | Other | explainlikeimfive | {
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"Vertical blinds are easier to repair - you only have to replace the broken individual pieces. Horizontal blinds are all tied in so it typically involves a complete replacement. Further, vertical blinds are much better for sliding glass doors and the windows are frequently matched to the door."
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743ues | Before modern times, how were brothels able to function w/o women being constantly pregnant? | Biology | explainlikeimfive | {
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"Well, I know for one thing that [condoms have existed for a long time.]( URL_0 ) I'm sure there were other methods, though.",
"There are natural herbs that if you process them correctly can be very effective abortifacients. They’re usually made into strong teas that you drink after you realize you’ve missed a period. Granted, they’re effective because they’re often toxic as hell and you’ll be ungodly sick for a while after taking them."
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743wgx | Is it ever possible for all currencies to hold the same value? If yes, how? If no, why not? | Economics | explainlikeimfive | {
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"In theory? Sure. In practice? That would require every country to be on equal footing economically with each other to the point that prices were identical everywhere. At that point we'd just consolidate to one currency and be done with the whole mess because *apparently* we fixed scarcity.",
"Is there a point of having different currencies if they all have the same value? Possibly ELI5."
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7447h6 | How is it possible to cook while camping without being attacked by animals? | Other | explainlikeimfive | {
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"Most animals are timid around humans. Even large predators like bears and mountain lions are usually hesitant to approach them. The reason being that any injury could very easily lead to infection or being too injured to catch prey and thus death. This is especially true of the people are in a group. However, bears can and will smell out food left out unattended, ripping open bags and containers to get at it. Thus when camping in bear country, you pack all your food in a bag at night and hang it in a tree away from camp.",
"> Wouldn't the smell attract every nearby animal that eats meat to your campsite? Wouldn't you be surrounded by hungry bears or mountain lions by the time your food is ready?? Smelling meat is something which may attract predators, that is true. But smelling *cooking* meat can only mean one thing: Humans. Traditionally speaking humans have been by far the most terrifyingly lethal predator in any environment and most animals will respect this fact. While these days they might come across some helpless city slicker who couldn't fight their way out of a wet paper bag, the instinct to avoid humans have been bred into wild animals from a hundred thousand years of primitive humans who ruthlessly slaughtered any animal foolish enough to stumble into a human camp looking for food around the campfire."
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744b52 | Why does cold water splashed on your back feel more intense than other areas of your body? | Biology | explainlikeimfive | {
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"Becuaese your body is most concerned about your core temperature. And your core temperature is higher than the rest of your body. Thus not only do you notice a change in temp more, but there is a bigger change in temp to notice.",
"Fourier s law! Heat transfer thru conduction is linearly dependent on Surface Area (big ole' piece of back skin) plus the temp difference (big ole' internal core temp). Bigger of each, bigger you're going to feel heat getting taken from you. Cus keep in mind, when you touch something, you're not feeling its temperature. You're feeling how quickly that material can steal heat from you. Cus all the items are at room temp (approx 70' F) while your body is around 98' F. Every item in the room is going to be roughly the same temp (room temp- and don't be a dick about 'air flow' or 'heat from other sources') but picking up the metal cookie sheet sure does FEEL a lot colder than picking up the wooden cutting board. Coupled with convection. But I don't know how that would do anything. Besides maybe cus the water is moving so fast, and it's all squished together in big globs of water. Cus in the shower you're hit with a bunch of drops but in this case it's just one big bucket of water. Plus the chaotic turbulence in the water makes it steal a lot of heat from you. But my original thought was just cus you usually only feel fabrics up against your back, unless you're mentally prepared & taking a shower or swimming. So I figured that since it's such a bizarre feeling compared to what your back is used to feeling, that's why it's so much more sensitive. Shit if I know tho."
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744p30 | How can sounds from earphones sound like they are in front or behind us? | Physics | explainlikeimfive | {
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"People find it amazing that something that only has two speakers positioned over your ears can create full 3D sound, but think about it - You only have two ears and yet you can hear stuff in front of and behind you clear as day. How does that work? The answer is the part of your ear called the pinnae. That is the bit you can see, the ear-shaped part, with the wrinkles and folds in it. What they do is modulate the sound based on where it's coming from. That's a big fancy word for 'change' basically. Your ears face forwards, so naturally sounds from behind are going to have a slightly different sound to them. A bit more muffled perhaps, an element to it is going to be changed. It's also about timing between the ears, volume differences between the ears, tonal changes. All of that is enough to be able to give you pretty accurate full 3D surround hearing. How is this relevant? Well introducing something called a [binaural microphone]( URL_1 ). As ridiculous a looking device as that is, it's point is to allow you to record those subtle changes that the outer ear makes on the sound based on the position of the sound source. They can be used directly to make recordings, in which case you end up with things like [this]( URL_0 ) (worth wearing headphones if you listen to that), or they can be used for something a bit more clever. If you play various test tones and other carefully selected sounds from carefully controlled and recorded positions around a microphone like that, you can begin to make a record of what these modulating effects are, for a given location. If you do enough of it, you can create a sort of audio template of how the sound changes based on position all around your head. Once you have that, you can filter audio through it, say surround sound audio for a movie, and you can create a true, two channel 3D sound output."
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744te7 | how do we create sounds and noises that we want to make? | Biology | explainlikeimfive | {
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"Practice. Speech is learned. Babies experiment with making sounds (babbling) until they become more proficient at controlling their verbal output. Comprehension is present before children are physically capable of speaking, which is why some parents teach their children primitive sign language. If you want to make some sound that you don't know how to make, you use trial and error to try to produce it. Our brains have evolved to produce verbal outputs in the same way that they have evolved to produce walking and running. Once you know how to do it, you don't have to think about it."
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74520a | what's the projectile difference between an aluminum and wooden baseball bat? | Other | explainlikeimfive | {
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"text": [
"Here's an article explaining it: URL_0 tl;dr: aluminum bats can be swung faster because they're lighter, they have bigger sweet spots which make hitting farther easier, and they don't break/splinter like wooden bats."
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74587x | How does concrete set with water, but after its set, water can be applied that doesn't render it back to original separate contents? | Chemistry | explainlikeimfive | {
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"\"Setting\" isn't \"drying,\" it's an irreversible series of chemical reactions like burning or corroding. The water is chemically consumed in this process and becomes part of the final concrete material. You can't un-rust iron by adding more oxygen and you can't un-cure concrete by adding more water."
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745i7c | Unsolved math problems. | Wikipedia has a long list of unsolved math problem in fields of Algebra, Geometry, etc. Why do we still have these kinds of unsolved math problems in the era of supercomputers? Follow up: can you give an ELI5 example of a famous unsolved problem? Most of the descriptions are too complicated to understand. | Mathematics | explainlikeimfive | {
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"In its stead, I'll give you a fairly recently solved problem. 3^2 + 4^2 = 5^2 That's called a Pythagorean triple, and there are very, very, very many of them - that is, two integers which can be squared to return a third squared integer. A^2 + B^2 = C^2, for very many integers A, B, and C. Now - are there any positive integers such that A^3 + B^3 = C^3? Nope! Now, we really suspected that for a while. We did it by hand, we calculated so many sums of cubes, and we couldn't find any such triplets. We told our computers to do it, and they worked until the numbers were big enough that the work was painstakingly slow, and they didn't find any. But did that prove that there were none? Some guy Fermat who had kind of a big mouth wrote in the margins of a book of his that he had a wonderful proof that there were no such triplets at powers higher than 2, but he [\"didn't have enough room to write it in this margin\"]( URL_0 ). That was centuries ago, and NOBODY could find that proof for a VERY long time. It was only in the 90s that a guy named Andrew Wiles proved it. He didn't prove it by having a computer check every integer triple up until infinity. He didn't prove it through any simply described process as is that by which the Pythagorean Theorem or the irrationality of 2 is proven. His is an enormously complicated, enormously long proof that defies ELI5. What computers are good at is checking lots of triplets of integers and seeing if they match the pattern, but there are infinitely many triplets to be checked. The tricky part which nobody has really figured out is how to get them to think outside the box to prove theorems. *Disclaimer: Fermat was virtually certainly talking shit or at best referring to a simple \"proof\" that is known to exist yet has a barely noticeable flaw rendering it invalid.*",
"Here's another example of a problem which is simple to state but is so far unsolved. Suppose you have a natural number, like 7. If the number is even, you divide it by 2. If the number is odd, then multiply it by 3, and add 1. If you repeat this process with the number you get, you generate the sequence 7,22,11,34,17,52,26,13,40,20,10,5,16,8,4,2,1. The question is, will you always get 1 eventually, no matter what number you start with? Nobody knows. This is called the Collatz conjecture.",
"It would be pretty cool if you could just ask a computer whether a mathematical statement is true and the computer would dutifully spit out a proof or disproof. It turns out that one of those famous unsolved problems is the question of whether you can program a computer to do that efficiently. (Glossing over the technical details.) Here's another unsolved problem, named [Goldbach's Conjecture]( URL_0 ): is every even integer greater than two the sum of two prime numbers? Such a simple question, but how could you get a computer to answer it? Trying a bunch of numbers doesn't help, because there are infinitely many even integers and you can only try finitely many. Computers have checked up to about 10^(18), but almost all integers are much, much larger than that.",
"unsolved math problems require proof for a theorem. Many of those require finding ways to express the problem in literal math (not using numerals). Computers are good to crank up numbers once the formulas have been defined. Looking for ways to express formulas to meet a certain criteria is not something that can be easily done with current programming languages.",
"You usually can't prove a theorem using bruteforce. Even relatively small and simple structures may contain infinite amount of elements, so it is just impossible to search through all of them. For example, you can't find the amount of prime numbers using bruteforce methods, because you will have to check infinite amount of odd numbers. Reductio ad absurdum however allows you to prove that theorem without any calculations. Here is one more unsolved yet problem for prime numbers: is it always possible to represent even number as a sum of two prime numbers (p1+p2=2n)?",
"> Wikipedia has a long list of unsolved math problem in fields of Algebra, Geometry, etc. Why do we still have these kinds of unsolved math problems in the era of supercomputers? Computers are NOT intelligent, they are very good at following orders exactly and quickly. You need to implement the theory correctly to get anything out of a computer, no matter how fast it is. With the example of /u/henstepl it seems like you should just be able to try all combinations with a super computer, right? Not really, because integers keep going to infinity, if they were limited, that would be true. Trying infinitely many combinations, takes an infinite amount of time, no matter how fast your computer is. So instead you need to rely on proving in some manner that goes on to infinity, a common method is *proof by induction*, that is, if you can prove that something holds for a value n, then prove that it also holds for n+1. Then, since n can be any number, can also be n+1, so it also holds for n+2, and so on to infinity. Typically, these kind of proofs do not require huge amounts of computations suitable for a super computer, because you just need to calculate two steps, and can skip looping all the way to infinity.",
"Since one of your comments asked if one of these unsolved problem have any real impact, here it is one. One of the most important equations in fluid dynamics is the so called Navier-Stokes equation. I'm not really knowledgeable in this field, but its importance is clear. From the behaviour of weather, or the optimization of the aerodynamics of a vehicle, these equations are important. In general a mathematician is not concerned in finding a solution explicitly, but rather in stating if the solution exists, is unique, and what kind of solution it is. For differential equations there are various concepts of solutions, each with it's peculiarity. For this equation in particular, we don't know if a smooth solution exists and is unique in the 3 dimensional space (the case most interesting to us). Albeit we are able to \"solve\" this equation by simulating, we still lack some theoretical properties. And solving this would expand out knowledge a lot, even for practical purposes. The point is that you have to imagine that if you study mathematics post high school, you stop dealing exclusively with calculations and start dealing with ideas. Some concepts are not easy to express in a machine. How do you express the simple concept of limit, when it requires checking the validity of a statement for infinite cases? Only with an analytical reasoning that shows that no matter what the number the thesis holds it is possible. We will reach the point where computers can do this kind of reasoning probably, but we're not there yet. I work in stochastic analysis, and my focus (only focus since I'm just a PhD candidate) is studying some reflected stochastic equations and proving that a solution to this equations exists, is unique, and has some properties. This cannot be done by a computer (yet) because it involves both understanding some stuff about the theory of stochastic processes, and then creating both a sequence of particular elements and ad hoc estimates to show that this elements \"converge\" to a certain element that has the properties needed to be a solution. A computer cannot (yet) guess the kind of analytical (or if you want symbolical) calculations to make."
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745k6b | Why do personal care products come with both English and French translations as opposed to English and Spanish like so many other products? | Things like soaps, shampoos, and other hygiene products. | Other | explainlikeimfive | {
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"A lot of them have the same products being made for both the American and Canadian market, and Canada legally requires product packaging to be both in English and French.",
"I believe that there is a Canadian law that requires products sold in Canada to feature both English and French on labels It always made designing literature for my company difficult for products sold in both the US and Canada - gotta fit a lot of words in two languages on a small package...."
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745q1e | Why does the NRA wield so much power? | Other | explainlikeimfive | {
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"They actually don't. The truth is, they don't wield as much power as gun-control advocates would have you believe. Making the NRA, and the gun industry in general, seem like an all powerful boogy-man removes the human element. It's easier to hate some faceless company, especially if they're seen as rich and powerful, then it is to hate on uncle Joey, who likes to hunt in the fall. The industry as a whole has nowhere near the financial clout that other industries have. They do, however, have a strong base that votes, so that is where most of their influence is.",
"Because people(voters) listen to them, and they're extremely influential in getting people to vote a certain way, or just GOTV in general. They don't (relatively speaking) have a massive warchest. In our political system, votes are power, and the NRA mobilizes a hell of *a lot* of votes. Not having an NRA endorsement (or having it go to your opponent) can be extremely damaging to your reputation in a lot of districts. Usually rural/conservative majority districts, but not always.",
"How about doing a little research and comparing contributions by the NRA to those of labor unions, various corporations, and other bodies. They don’t have 1/10 the influence you think they do – if you’ve been paying attention, they are simply a convenient scapegoat every time something like this happens.",
"Because it's the largest lobbying party in the country. If you are for gun control, they will target you and attack your political presence with mere numbers and financial backing, people love guns.",
"They don't. Jimmy Kimmel is lying and has politicized a tragedy before the blood's dried. Imagine that."
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745tcr | What is physically happening when you have a stuffy nose? Why does your nose continue to feel stuffy and blocked even after blowing your nose? | Biology | explainlikeimfive | {
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"It stays blocked because the lining of your sinuses actually swells up, making your sinuses constrict. The more you blow your nose, the more you irritate that lining, thus leading your sinuses to swell more and further exacerbating your stuffy nose."
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746mt4 | why are some developed countries, like Sweden, so advanced in terms of taking credit cards in shops etc., while other developed countries like Germany are so behind? | Economics | explainlikeimfive | {
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"That question implies that using credit cards is the direction you want to go in as a country. Not everyone might share that view. Or in other words, many of us germans just like cash.",
"You can pay by credit card in many German stores, but Germans tend to be a bit skeptical. Reasons include: 1. Credit cards are expensive. Credit card companies don't provide their services for free, so there's a fee for their use, although it's usually well hidden. And you also have to pay interest on your purchases, because credit cards work by granting you credit. You just don't notice it. 2. Credit cards are not as secure as is usually claimed. Old-fashioned credit cards could be used by anyone who happened to know the number, and that includes every store, restaurant or other establishment you use your credit card in. Even modern credit cards with chip-and-PIN technology, which are the norm in Europe, aren't entirely secure. I can't remember the last time I had to enter my PIN to pay a hotel bill or buy a train ticket. 3. Paying by credit card takes longer and is more hassle than cash. 4. If you lose your wallet with €100 in it, you've lost €100. If you lose your credit card, you have to hope that you notice the loss and get it cancelled before somebody else can go wild with it. 5. During the course of the 20th century, Germany saw two totalitarian regimes that kept tabs on everything their citizens did. As a result, Germans are very protective of their privacy and very cautious of anything that might leave a paper trail. Cash is guaranteed to be anonymous. 6. After WW2, Germany rebuilt its banking system more or less from scratch. Instead of cheques, they used a system of direct bank transfers with several safeguards built in. This was great for mail order purchases, and so when online shopping became a thing, they simply continued to use that system, meaning they didn't have to get credit cards. A transfer initated by the payee can be easily reversed up to 13 weeks later: it's a routine procedure, which gives consumers added protection against unauthorized payments. With an online banking service, reversing a transfer is a matter of a couple of mouse clicks.",
"germany isnt any less developed. you can pay with credit cards just fine nearly everywhere. germans just dont like credit cards. source: am german, working for a huge company selling products on the phone to german customers. since we abandoned the classic wire transfer (which is what germans love) and only offer creditcard (and paypal), a lot of customers are really pissed off. /edit: they are pissed off because the majority of germans simply dont have credit cards, unless they are globe trotters that need it to be able to pay abroad.",
"Germans are extremely concerned about privacy and information security, and more cautious about debt than most people. I am an American who moved to Germany, and the first time I tried to do a money transfer, my wife explained how I needed to stick my debit card into this little reading device at home, enter a password into it from the online banking website, confirm the exact amount and routing number of the recipient of this device, then enter into the online banking website another password given to me by the device. Some German credit cards have an extra security code (not the 3 digits on the back) that websites require when buying things online. Not using cash can be a pain in the ass. The other part of it is that Germans simply like cash. It is frowned upon to buy a few beers from the kiosk with a credit card. It rubbed off on me quickly. Just six months living in Germany I came back to America and I got angry at a guy in the 711 buying a pack of cigarettes with a credit card. I actually thought \"carry some cash, damn you!\"",
"Does that include debit cards too? Some people don't like credit cards because they don't like going in to debt, but that's a separate, unrelated question. So the question should really be about debit cards, and Germany has the existing Girocard system for that. So Germany is *not* really behind in that respect.",
"If I am not mistaken most card in Sweden are debit card not credit card. The difference is that debit card remove money directly from you bank account versus you get a bill that you have to pay at a later date. If you card has no credit it is no difference then to take out cash at a ATM and use it except that you don't need to handle bills and coins A reason might be difference in law. If I am not misstanken there are no legal requirement for banks to provide cash services and most banks offices today are cash free. It cost money to handle physical money and the banks have tried their best to recuse costs by moving away from cash. German laws might have different requirements. Cash is not need in Sweden for simple transfer of money between individuals. There is a payment system called Swish supported by the banks that provide simple money transfer by using the phone number as a identifier of the receiver. It is free between individuals but companies and other organisation have to pay a fee. Online purchases had been introduced this year",
"Germans are big on cash. The most common ways to pay for something is either in cash or by directly transferring money from one account to another. Credit cards are also used, but much less. Things like cheques are basically non-existent. Credit cards offer few benefits compared to the bank cards issued by your bank and linked directly to your account and they cost extra. Small businesses with small margins largely don't see the benefit of giving money to credit card companies and the customers don't pressure them to do so. Germans like paying in cash for big purchases and they are the main users of large denomination Euro bills. Germans also really don't like the idea of debt and credit. They go into debt as much as anyone else, but prefer to save up rather than pay of later.",
"Honestly, I find it's the other way around, why use credit cards when there's the option to instantly wire money?",
"Part of this is that Sweden has caught on to the mobile payments bug a lot earlier, thanks to companies like Nokia and Ericsson being neighbours. People realised the value in paying by phone years ago, by SMS. Part of this lead to infrastructure for card payments being everywhere right about when chip cards became prevalent, then contactless. Also one thing holding back Germany and The Netherlands is a localised system of payment, primarily of their own EC/Maestro cards which haven't been as \"industry standard\" as Visa/Mastercard.",
"Yesterday I paid my parking fee (2,40€) at the parking machine with my debit card. Witch means I spent money I have vs took a loan from the bank to do it (that's what credit cards are). I pay 7€ to my bank each month for this and it also includes any money transfer via web and the basic features of an account. When I made a credit card I paid 60€ per year just to have it. I draw about 4 or 500€ per month from an ATM (also for free) to do all the small payments. All the rest is done via debit card or online. What's the advantage of a credit card except huge interests if you do not have enough money at the and of the month? I live in Italy btw ."
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746qfy | Why is Bill Gates worth so much as opposed to Warren Buffet or Jeff Bezos, even when accounting for his philanthropy and donations? | Economics | explainlikeimfive | {
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"Amazon is mostly US based and Warren Buffet sold most of his partnership. Windows is most used world over",
"Note that Warren Buffet is explicitly giving away his money, and has already [given nearly $20 billion] ( URL_0 ) to the Bill & Melinda Gates Foundation Trust. That's about half of the Trust's assets of $40 billion, meaning that $20 billion came from Bill - but that $20 billion is still counted as as asset on Bill's books, since it's held in trust and wasn't a donation. So that explains why Warren Buffett isn't $20 billion richer.",
"Your premise is incorrect. According to Wikipedia, Bill Gates is worth $89.2 billion, Warren Buffet is worth $76.7 billion and Jeff Bezos is worth $82.6 billion, all around pretty similar numbers."
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746s7s | How complex are animal 'languages'? | So, as pretty complex animals, humans have pretty complex languages and can discuss all sorts of things. Most animals are much simpler, but do we know how simple their communication is? Sure, some animals are fairly quiet and only make sounds when in distress etc, but many animals are much more vocal (like common birds). Are they actually talking about things or just trying to be heard? And as for animals that work in packs or groups, do they have a proper line of communication or just act on instinct? | Biology | explainlikeimfive | {
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"TL;DR: VARIES GREATLY by species and native intelligence levels. There's a tremendous variety in the levels of intelligence and, alternately, cleverness, in various animals. This often translates directly to the complexity of their language. Same goes for pack behaviours: some are learned (e.g. lions hunting), some are purely instinctual (e.g. division of labour in termite nests). And it's important to realize that language is not limited to vocal elements - body languages, smells/pheromones (particularly during mating seasons) and dances often contribute to communication between animals. In very rough and debatable order, and there are all sorts of other examples: Most insects don't really communicate beyond the instinctual level. There's no actual thought behind it, it's just automatic. One of the more sophisticated communications is bees \"dancing\" the direction and distance of fields of flowers when they arrive at their hive. Reptiles and amphibians have vocalizations that mostly announce their presence, although frogs can get into some pretty loud \"hey this is my territory\" duels during summer nights at the pond. Fish are mostly instinct-type communicators. Some use visual signals and water pressure changes in schools, helping them to coordinate movement. A few vocalize. Squid and octopi can send visual signals to each other through changing the colour of their skin; some are thought to be as smart as dogs. Birds are near the top of the list, with highly intelligent gray parrots being taught huge vocabularies of human words to the point where some can make their own sentences. As superb mimics, they have the advantage of being able to actually shape their communications to exactly match our own. Many other species have more limited vocabularies that they use among themselves, with word count ranging from a few basic calls for nighthawks to a high number of different coordinating communications for crows. Then there's mammals, and most use just basic words like wolf howls or happy barks to communicate. Some are even dedicated to crossing species; cats meow at humans but not so much when we're not around. Cetaceans like dolphins and orcas and whales have very complex songs though, and a lot of fairly complex communication goes on between them. There's a lot of non-verbal communication that happens in chimp tribes.",
"Animal communication is a very complicated and little-understood subject, but from available evidence it would appear that no form of animal communication comes anywhere near the complexity of human language. Very complex birdsong is mostly just showing off -- \"Listen to all the different sounds I can make!\" The typical things a bird might \"say\" are: \"I'm horny,\" \"This is my patch and I will defend it,\" \"I'm here,\" \"It's time to flock together and migrate, who's with us?\" and \"Danger!\" Wolves certainly do use communication to coordinate their actions. It's not just vocal, but body language as well. They even appear to vote: if their leader wants to, say, go hunting, they might gather and then cast their votes by sneezing. That's a very sophisticated form of animal communication, but human language still knocks it clean out of the water. We can talk about abstract things, we can talk about things happening in different places or at different times, we can even talk about things that haven't happened yet or may never happen at all. By contrast, animals appear only to be able to communicate things that are happening *here* and *now*. Another feature of human language is that it is \"open-ended\" and \"productive\". This means that although we only have a finite number of symbols (sounds and gestures that make up the language), we can talk about an infinite number of things, including things nobody has ever talked about before. Animals by contrast can only talk about a finite number of things: they can say, \"I am hungry,\" but they can't say, \"A rose by any other name would smell as sweet.\" There are claims -- and they are very controversial claims -- that primates can be taught to communicate with humans in ways that mimic human language. The most famous is Koko the gorilla, who has been taught American Sign Language. The researchers working with her claim that she can not only talk about things that happened in the past, she can even make up her own phrases (for example, signing \"dirty bad toilet\" as an insult). But some linguists are skeptical of these claims, saying that the signs Koko produces are so vague and poorly executed that you can't tell what, if anything, they mean.",
"It seems to be very primitive, but some birds do seem to have different words for different types of threats. So, instead of a general \"predator\" they have \"falcon\" and \"panther\" cries."
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746uva | How does the sun ''burn'' ? | Physics | explainlikeimfive | {
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"It's a giant ball of gas, about 300,000 times the mass of the Earth. All that mass produces gravity. Take the gravity on Earth, holding you onto the ground - it's rather gentle. Multiply it by 300,000 and you can imagine some interesting things can happen. The main thing in the Sun is that immense pressure forcing hydrogen atoms together into helium atoms, producing a lot of energy each time. That's the \"burning\".",
"It's a giant angry fusion reaction, it's blasting energy and particles into space. The ones that burn your skin are the high energy ultraviolet rays. The photons of UV can hit molecules in your skin cells and damage them, like tiny little bullets. This can even cause cancer if the \"bullet\" of UV hits some DNA, and then DNA repair makes an error, and you get melanoma. Your skin adapts to protect you from UV by producing extra pigment, melanin, that absorbs light & UV. Don't forget your sunscreen."
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747mgf | Why do our bodies wait until we're soaked in sweat to wake up when too warm at night? | Biology | explainlikeimfive | {
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"Talk to your doctor about night sweats... among other things could be apnea, and be a sign you are having severe breathing problems leading to lack of oxygen. Leads to your heart racing to get more oxygen to your brain, and then profuse sweating bc your temperature gauge is in the base of your brain and all that hot blood getting pumped through make you think you're overheating. Also could be why you aren't waking up earlier or remembering doing so -- with apnea you get so used to waking up and going back to sleep that it doesn't register. If you also snore, I'd wager that's the issue.",
"Normally, they don't. Most people wake up before they're soaked with sweat. Most of the time, anyway. Night sweats are usually associated with some other, underlying problem. Could be any of a variety of things. Night sweats are a common side effect of any number of different medications, to say nothing of drug/alcohol use. There are also quite a few medical conditions that have night sweats as a common symptom. Some are quite serious (e.g., HIV/AIDS, intestinal cancer, stroke, leukemia, etc.), others more manageable (e.g., sleep apnea, diabetes, menopause, etc.)."
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747nwi | Why do cops in movies and TV shows taste the cocaine before saying something like "take him away" or "jackpot"? Isn't ingesting coke dangerous, and illegal? | Other | explainlikeimfive | {
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"Maybe in the 80s they taste tested it... its cooler in the movies then busting out a testing kit and going csi on it It tastes chemically...then numbness and thats how you know its not powdered sugar. The amount being consumed in a touch'n'taste is too little for any significant effect beyond local numbing. Insufflation not only involves a larger dosage but also provides a more conducive path of absorption.",
"First of all, cocaine is a local anesthetic. The tiny amount one picks up by touching a pile of cocaine with one's fingertip isn't enough to do anything serious, but it's enough to cause brief, local numbness on the tongue. It's one of the only white, powdery substances that can do that, so it's a quick and accurate way of determining whether the perp has a bag of coke or something innocuous (e.g., powdered sugar, baking powder, etc.). Believe it or not, unlike most street drugs, cocaine isn't a schedule I substance (i.e., totally illegal with no recognized clinical use). It's schedule II (i.e., rigorously controlled, but available via prescription). It's still occasionally used as a topical anesthetic in sinus surgeries. It is no longer the *preferred* agent most of the time, but there are apparently certain situations where it's the right tool for the job, as it were. Many ENT (i.e., Ear, Nose and Throat) surgical clinics will have a supply of it on-hand at all times. But second, law enforcement doesn't use this method of field testing nearly as often as it used to. And it probably never used it as much as movies and TV shows would lead one to believe. Why? Because having a cop take a quick taste of a suspicious powder is visually effective and *quick*. Waiting for them to bust out a field chemical testing kit (or, even worse waiting for one to arrive on the scene from somewhere else), and then watching someone perform the relevant chemical test, is *boring*, both visually and dramatically. Chemical testing kits are cheaper and more widely available than they were fifty years ago, so there's even less reason for actual cops to do this today than there ever was."
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747o5e | What is the origin and/or purpose of the 5 cent refund on glass bottles? Why do only some states have it? | Economics | explainlikeimfive | {
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"It is intended to create an incentive to recycle. It probably was a bigger incentive when five cents was a more meaningful percentage of the purchase price than it is today. Only some states have it because only their lawmakers saw fit to create a law to put the system to deal with it in place (which costs money to as inter also).",
"Michigan has a 10 cent refund on all bottles and cans (not water) to promote recycling them. People take them to the store all the time here to get money back. You rarely see cans in the street or garbage because people pick them out. I took them back all the time as a kid to get extra money. Usually wound up with about $10-20.",
"Once upon a time soft drink manufacturers sold all soda inside of glass bottles. These glass bottles could be returned to facilities for free to be refilled or recycled. In some places you even had Glass pickup that would take your bottles back for you. Then they discovered they could put their soft drinks inside of plastic. Suddenly there was no more reason to take back the plastic and the consumers were left with no real idea of how to handle the stuff. Bottles became disposable and it lead to a massive uptick in pollution. Soft drink manufacturers started getting blames for this wasteful practice and people wanted them to shift back to glass... The manufacturers responded by: 1. Lobbying congress extensively to prevent this. And 2. Creating ads to guilt people like the oh so famous crying native American advertisement. Suddenly it became about public responsibility and not about companies having to take care of the mess they made themselves. Many states adopted a soda tax to encourage people to bring back their used bottles for money, and it worked."
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747qjb | why are unmanned planes/helicopters named after male bees? | Technology | explainlikeimfive | {
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"In the 1930s there was a kind of British plane called the [de Havilland Tiger Moth]( URL_0 ). They made version that was a remote controlled plane to practice shooting at it. They called this the Queen Bee. The Americans saw this was nice, so as a play on words, when they started making their own remote controlled planes they called them Drones in reference to the Queen Bee",
"At the risk of being pedantic, there is a clear distinction between \"drones\" and \"unmanned aerial vehicles.\" An unmanned aerial vehicle or UAV is a remote piloted aircraft with a human controller. They're still called \"drones\" by the media and in non-military circles, but that's technically incorrect. Drones are piloted by a computer program. < /pedant > To answer your question, a drone has nothing alive on board. It's flown by radio, and the name \"drone\" comes from the fact that it's mindless. We also refer to listless and unimaginative human workers as \"drones\". A drone in a bee hive doesn't seem to have much of a mind of its own either. Drone = mindless/mechanical/robotic/not human."
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747vpu | Why are there so many more shootings, attacks, and bombings in Europe than the US When the US is more actively involved in destabilized regions than countries, for instance, like France? | Other | explainlikeimfive | {
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"1. There aren't more shootings in Europe than in the USA, but there are more Islamic terrorist attacks, which I presume is your point. 2. Europe is more populous than the USA, the EU alone has over 500m residents. More people = more stuff happening. 3. Europe is closer to areas of unrest and shares land borders leading to the whole of Eurasia. You can walk from Beijing to Lisbon, so it's easier for terrorists to get around. 4. As a collection of countries it is more difficult for Europe to have unified action. Sharing intelligence and coordinating operations is more difficult when dealing with multiple governments and a large number of languages. Of these I'd suggest that proximity is the biggest factor. Europe is a closer, and therefore, easier target.",
"Because the US has a very handy natural border between their nation and the \"destabilized regions\" you are referring to. Two very large oceans. It's extremely difficult for people in those regions to get to the US and when the US does take people, they do extensive checks on those they receive. Essentially cherry picking refugees from European countries to ensure there is the least chance possible that anyone that comes to the US is a disgruntled, displaced person who might attack US citizens because they blame the US or Western countries in general for their situation.",
"Because the terrorists don't just hate the US, they hate any westernized country and its beliefs. Those countries are way easier targets because they don't have to take a plane to the US to get there and it's harder to peg someone as a terrorist in those countries because to my knowledge it's illegal to look at a Muslim man as anything but just a Muslim man. I'm not saying all terrorists are Muslims, but you get my point."
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7482dh | if viruses (and such) keep mutating and given enough time, wouldn't something that was easily curable become very dangerous? | I've read some recent articles of certain strains becoming resistance to certain drugs but given enough time, wouldn't that virus/disease become completely immune to everything we can throw at it? Would there be anything would could do at that point? Also, wouldn't something like the common cold, for example, have a high chance to mutate due to the amount of occurrences. Thanks! | Biology | explainlikeimfive | {
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"First, as has been pointed out, viruses and bacteria are not at *all* the same things. Most bacterial infections can be \"cured\" with antibiotics. There is no cure for viral infections. The immune system either beats them, or it doesn't. Treatments for viral infections consist almost entirely of alleviating symptoms, or just keeping you alive long enough for your body to fight off the infection. Second, bacterial resistance to antibiotics is a problem. . . but not in the way you seem to think. It doesn't necessarily make bacteria any more deadly than they were before. Take something like *E.coli*, the most common foodborne illness. In most cases, people get better after a day or two without taking antibiotics. Which is just as well, because an increasing number of *E.coli* strains are becoming increasingly resistant to antibiotics. But that resistance, while problematic, does not actually make the bug any more *deadly* than it was before. Which is to say, not very deadly at all. Third, viruses can and do mutate such that previously innocuous strains can suddenly become exceptionally dangerous. That's thought to be what happened with the Spanish Flu epidemic in the 1918-20. It's known that the influenza strain in question was H1N1. You may have heard of that in recent \"swine flu\" outbreaks (2009 in particular). No one really knows why, but in 1918, the H1N1 virus suddenly became drastically more deadly, killing more people in two years than there were military casualties in WWI and WWII *combined*. And nobody really knows why in 1920 it just as suddenly became drastically less deadly. There are a number of theories. One is that it was *so* deadly that too many people outright died before passing on the nasty form of the virus for it to successfully survive. Another is that just as one mutation caused it to be extra deadly, another mutation made it less so. Hard to say. But whatever the reason, we do know that *particularly* nasty diseases--whether viral or bacterial--seem to have a tendency to die out after a while. Whether it was the Black Death in medieval Europe (bacteria), Spanish Flu in the twentieth century (virus), or Ebola in West Africa (virus), exceptionally lethal diseases have a tendency to be self-limiting even in the absence of a cure/vaccine. Indeed, any disease with even a moderate mortality rate (e.g., measles, which has an 0.2% mortality rate in healthy people and only a 10% mortality rate in the highly undernourished) is a *really big deal*. A disease with a mortality rate well into double digits (e.g., Ebola) often finds it hard to spread far and fast enough to kill all that many people in absolute terms. That this tendency may have something to do with the fact that so many people have died that the disease just can't spread any more is *depressing*, but does nonetheless tend to set some outer limits on just how lethal diseases can remain over time.",
"You're lumping viruses and bacteria together when they are two very different things. Viruses have a protein covering on them that protects the genetic material inside. Your body makes antibodies to latch onto these protein coverings like a locksmith making a key to fit a lock. Unstable viruses such as the common cold mutate frequently, generally by rearranging the proteins on the outside, which acts like changing the lock. So the next time it infects, the current antibodies no longer work because they are keys for a different lock, and your body needs to make different antibodies. This does not make the common cold more dangerous over time; it simply makes it so you can't become immune. The actual infection itself remains unchanged. Though some viruses that are mild in animals can mutate to infect humans, and this often makes us much sicker since we are not the intended host. The flu is notorious for this (recent examples include bird flu and swine flu). HIV and ebola also did this. Bacteria are the ones that become resistant to antibiotics over time, which makes it harder and harder to treat them. Most bacteria do not increase in severity when they mutate, they just become harder to kill. But yes, it does get to be a problem when these bacteria become immune to multiple antibiotics, especially when the patient is also allergic to other antibiotics, such that there are no real good choices. There have also been reported cases where bacteria have been found resistant to all antibiotics tested. And untreated bacterial infections can become very dangerous indeed. It is a serious issue in medicine that the medical community is working on, but currently has no easy solution.",
"First, mutating and evolving does not mean getting more dangerous. The *potential* is there, but there's no guiding plan here. Random happens. That said, we do have stuff like MRSA which, while not a virus, is a bacteria that has become extremely resistant to antibiotics and is, indeed, very dangerous.",
"You are right that viruses and bacteria is constantly developing. And our immune system is developing to combat them. It is a constant battle that have gone on for millions of years. The common cold for example is usually just a few years old at any time. There are different strains every year and even multiple different strains roaming around at the same time. As we contract one strain our immune system develops resistance against that and it almost disappears. But another strain have mutated that we are not immune against."
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7482ri | What Happens where Predators eat body parts of animals that contain large dose of Venom, like the head of a Snake or the tail of a Scorpion? | Biology | explainlikeimfive | {
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"If the venom doesn't get stabbed into the bloodstream, then it will seem like nothing happened, and the predator will be OK. But what really happens is pretty neat. Putting something in your mouth and then swallowing it is ALWAYS safer than poking it into your bloodstream. Just like humans, many predators have a whole line of \"digesters\" that can make things safer to eat. First, there is spit - chewing and mixing with spit is important for digestion because it helps make big chunks smaller, it helps smaller chunks slide down into the stomach, and the spit helps some things start to dissolve. If you are chewing a venomous animal, there is a good chance that the chewing will burst the tissues where the venom is stored - that makes it less likely that the fangs or stingers can actually inject the venom. Once the venomous parts get into the stomach, the acids within the stomach are often strong enough to \"de-nature\" many venom proteins. \"De-nature\" basically means it changes shape to that it doesn't react the same way that it would have. Then other enzymes begin to break everything down into even smaller chemical bits. Those small chemical bits are mostly turned into new proteins that you need to rebuild your own cells, or energy that helps you move. So eating venomous animals is not a super idea, because there are some risks of the venom getting through your skin (or digestive tract lining) but the venom itself is usually not dangerous to digest. On the other hand, if you inject beef stew into your bloodstream, you could get very sick. EDIT: I'm forced to amend my dangerous comments, as follows - 1) Putting something in your mouth and then swallowing it is ALMOST ALWAYS safer than poking it into your bloodstream. If a doctor tells you otherwise, listen to your doctor. 2) Don't eat sacks of venom and don't inject things into yourself. EVER. If a doctor tells you otherwise, listen to your doctor. 3) Putting things in your butt is not quite the same as eating. But it is ALMOST ALWAYS safer to put something in your butt than it is to inject it. If a doctor tells you otherwise, listen to your doctor. 4) If you aren't sure whether to eat something, put it in your butt, or inject it, move on to something you are more familiar with. 5) I'm really surprised there weren't many responses talking about scorpions. They are good examples of animal magnetism in this crazy world.",
"In order for venom to be dangerous, it must enter the bloodstream. Many venomous toxins specifically target red blood cells themselves and break down those cells which results in organs being unable to receive oxygen. This leads to inflammation and necrosis of the cell tissues. Organ failure then leads to death. (Not all venom works this way. Sometimes venom attacks the nervous system instead.) When consuming anything, animals have several defense mechanisms in the digestive system. The first defense is the mouth itself. If the lips start burning, the animal might not swallow. Then, the taste buds help the predator know whether this should be swallowed if it tastes bad. Next, the saliva in the mouth and chewing action helps break down molecules and foods into smaller pieces. Saliva is also full of white blood cells (leukocytes) that attack harmful items (such as bacteria) that might enter your mouth. After the mouth, the item enters the stomach. The acids, heat, and enzymes in the stomach are capable of denaturing proteins. For proper protein function, the proteins must consist of specific shapes. By denaturing potentially harmful proteins, they are rendered harmless in many cases. They are also broken apart. [Gastric acid]( URL_0 ) in the stomach is normally between 1.5 and 3.5 PH. (Stomach acid can be incredibly acidic!) So, if it reaches this point, the venom is most likely going to be broken down in the stomach. However, if the venom happens to make it to the digestive tract intact, then it could potentially leech into your system. But, if it is possible for such a substance to reach this point, it is not actually a venom. It is a poison! To explain further, for an animal to be venomous, it must inject its venom by way of a sting or bite. For an animal to be poisonous, however, it does not inject the toxins in the same manner. Instead, you are harmed by swallowing the poison. So, if a snake was commonly eaten and it resulted in people dying, the snake would be considered poisonous not venomous for this reason. If this same snake could also harm people by biting them and injecting venom, the snake would then be poisonous and venomous! Most snakes are simply venomous. That is, consuming their venom is usually harmless. It is not recommended that you do so, though, since it could potentially be toxic if it passes all of the digestive defenses, and no matter what you consume, if you consume enough of it, it will kill you. The dose makes the poison. \"All things are poison, and nothing is without poison, the dosage alone makes it so a thing is not a poison.\" -- Paracelsus Edit: Clarification that saliva itself does not break down the proteins. That starts in the stomach. Note: Bloodstream is a simplified term and circulatory system would probably be a better term to use. Venom initially enters a different system designed to transport white blood cells and remove toxins from the body (lymphatic system). For some venom, the molecules are too large to enter the bloodstream itself. Comments from /u/KingKongBrandy and /u/Maj3sticCr0w led me to make this note.",
"ELI5- Venom is a small square box. Your bloodstream is a small square hole and your stomach is a small round hole. Venom is able to go through the square but not the circle because it's not designed to go through a circle.",
"Probably nothing. There's a difference between venomous and poisonous. A venom ingested doesn't have to be poisonous as it's often designed to interact with specific parts of a body. Usually the nervous system or blood. when the venom is ingested it most likely won't encounter those systems before it comes in contact with all the digestive enzymes that can break down the protein structure that makes up the venom.",
"I will add that many predators know to simply avoid the part of the body that delivers the venom. For example, meerkats adroitly nip the stingers off of scorpions and discard them before they eat their delicious land-lobster.",
"Nothing because venom is really just a protein that you can digest. But you had better not have a cut in your mouth or an ulcer in your stomach.",
"Venom does its thing from being in the bloodstream. If eaten, it won't enter the bloodstream until after it's been broken down and isn't harmful anymore.",
"Why capitalize the words you did? I thought this was about the movie Predators with Marvel's Venom. I wouldn't do that for clarity.",
"Venom is safe to eat, nutritionally it is essentially egg white. It only does it's work if injected directly into your bloodstream. If it was unsafe to eat it would be a poison. Venom works because it attacks the delicate and defenseless tissues where it's injected, either blood or nerves etc. When it dings itself in a well protected stomach it just gets digested since its only a protein like any other.",
"> Poisons are substances that are toxic (cause harm) if swallowed or inhaled. Venoms are generally not toxic if swallowed, and must be injected under the skin (by snakes, spiders, etc.) into the tissues that are normally protected by skin in order to be toxic. URL_0",
"Well Predators are space alien warriors. I assume they have trained their bodies to withstand upset tummies. Also venom doesn't do anything If eaten.",
"Poison will hurt you if it’s ingested. Venom will hurt you if it gets in your blood stream.",
"Poison in venom are different. Venom is aimed at attacking the blood stream, that is why everything with venom has sharp implements to deliver said venom into the victims blood stream. Poison on the other hand is just toxic so is bad for you whether it is in your blood or your stomach. I believe in Texas there is a rattle snake soup served with the venom in the dish, though they do warn you to make sure you have no cuts in your mouth before you dine. venom is perfectly safe to eat baring no compromised stomach lining/cuts.",
"So generally venom doesn't affect animals unless it enters the bloodstream (though there are a handful of animals that have venom that is also poisonous), so in theory ingesting it through eating it is harmless. In reality though it is possible to die (really only possible from really powerful venom like from a taipan or cone shell snail) or get sick from ingesting venom because it can get into the bloodstream through sores in the mouth and throat, or mucus membranes (though this generally is a small dose that gets in and is usually negligible). Due to this and the risk of being bitten/stung by their prey most animals that specialize in hunting venomous and/or poisonous animals have antibodies that break the toxin down making it essentially harmless.",
"Venomous =/= Poisonous Venomous - If A bites B and B dies, then A is venomous. Poisonous - If A bites B and A dies, then B is poisonous.",
"Without looking it up I'd say that the venom is neutralized, when swallowed, by acid and the proteases present in your stomach. Venom injected into the body on the other hand gets into your blood system and then you're fucked without access to some anti venom.",
"generally predators that hunt venemous animals are immune to that particular poison, at least a little. they can eat it or even get bit or stung and survive...might get a bit stoned but...other than that. take for instance the mongoose, or the honey badger, they can take a direct bite from their prey and survive.",
"If it is venomous then nothing since that venom only really works if it his your blood stream undigested. Poisonous on the other hand will kill the predator (think poisonous frogs found in amazon forests)"
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7483v1 | How do we know what continents used to look like in prehistory? | Other | explainlikeimfive | {
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"Do you mean how the continents used to be placed, as in how do we know about things like Pangea, etc.? Basically we know how the continents are moving *today*, which means we can estimate where they *used to be* by reversing that movement, and that estimate is then supported by physical findings. Example - say you are driving a car that you never clean, traveling along a single lane road for thousands of miles until you drive past my house. Now I'm a super fast mover like the Flash so to me you are basically paused and moving like 1 millimeter a year. I go to your car and examine everything. I note how fast you are going and how much distance you traveled during that time, so I can figure out where you'll end up in 1,000 of my years. By the same method, I can estimate how far back along the highway you were 1,000 years ago. I take a sample of all the bugs that splattered on the front of your car. It's a very insect-heavy region so there are literally layers of bugs coating the front. I notice that one layer contains a species of butterfly known to be local only to a very specific region 500 miles away. My previous estimate of where you must have been X years ago roughly places you in that region give or take a few years and now I have physical evidence supporting that estimate. So for continents, we know where they are moving and can estimate where they moved from; we have physical evidence we can date within the layers of the earth, and we have fossil records that support our estimates - things like a specific type of tree or species of frog or whatever - If we suspect that two areas *used* to be together, and they share the same type of fossil at roughly the same timeframe, it's good evidence that those areas really were together. It becomes more and more of an estimate the further back you go, so Pangaea is pretty well established but then things like Rodinia involve more guesswork, and when you get to stuff like Columbia supercontinent it is way more hypothetical URL_0",
"To add to the other answer. We also have fossils and sediment layers which show us that some parts of the earth were once covered in water. We also know that mountains were flat land and have been pushed up. The Rocky Mountains are still growing (I believe) and people have found fossils to show that they were once under water - flat land."
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7484by | How does archaeology integrate the concepts of anthropology, history, geology, and biology into its body of knowledge? | Archaeology seems like an interesting field for me but I don't really know much about the field in general and it seems like these fields of science are evident in the field at first glance and I'm really interested as to how archaeologists work their magic (for lack of a better term lmao) | Other | explainlikeimfive | {
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"Archaeology is known as a discipline that is extremely able to integrate concepts of other disciplines into their research, because they have many research questions that can be approached with those techniques and methods. For example, archaeologists can apply radiocarbon dating to find out how old organic material is, or can study dietary patterns through bone analysis. However, precisely because it can be such an interdisciplinary field, it is difficult for an archaeologist to be an expert in everything that is at his/her disposal. There are many archaeologists that have a general working knowledge of methods and concepts from other disciplines, and there are some that are specialised in a single other discipline (we then proceed to call them specialists, such as osteoarchaeologists for people that are specialised in analysing bone material, or landscape archaeologists/geoarchaeologists for people that are specialised in physical geography in the context of archaeology). Sometimes even people that have no affinity with archaeology are involved if the people working on a project have limited or no knowledge of the methods/concepts they need to use. More complex archaeological research is thus rarely conducted by a single person. Often there is a team of people involved, some of whom may be general archaeologists, some of whom may be more specialised archaeologists, and some may be trained in different fields entirely, depending on the kind of material that they are working on and the kind of research questions that are asked."
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748i3w | Does peeing directly into the water or on the side of the bowl keep your toilet cleaner? | Physics | explainlikeimfive | {
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"Side of the bowl gets rid of big splashes but you'll get a fine mist. in the water makes big droplets but i think you get somewhat less mist? sit when you pee at home and you basically don't need to worry about splash zones.",
"Side of the bowl. The water hits it at an angle and bounces downward towards the water. When hitting the water it’s forced upwards. Additionally, forget the cleaning issue. Hitting the water is disgusting, loud and horrible for anyone else within a city block to have to listen to."
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748ne2 | Why do we have baby teeth? | Biology | explainlikeimfive | {
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"It solves the problem of how you develop an adult jaw full of teeth, when all you have is a baby jaw. And the solution is, to grow a set of baby teeth, then let them fall out and regrow once the jaw is big enough to support a full set. You could imagine other solutions, this is the one that evolution chose."
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748seb | During a supernova, at what point does the implosion of a star change to an explosion, and what causes this shift? | As far as my understanding, when a star dies it collapses into itself under its own gravity. On the other hand, a supernova appears to be the exact opposite of this inward collapse. How does something start by imploding and then switch to a completely opposite action? Is there some type of triggering mechanism that decides at what moment the implosion turns into a supernova? If so, what is it? (PS: I posted it to r/askscience yesterday but it seems the mods haven't reviewed and approved it yet, so I thought I'd ask here.) | Physics | explainlikeimfive | {
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"[This video]( URL_0 ) explains the overall process nicely. But as you point out, they don't address this specific question. Stars start out as almost entirely hydrogen. The energy in the core pushes outward, while gravity compresses everything inward. When the star maintains size, these forces are equal and opposite. When the star compresses, gravity is winning over the expansive energies: And when it grows, the expansive energies are overwhelming gravity. As more and more matter gets turned into iron, the star begins to compress because the core is more dense than before, and gravitational forces are more intense as a result. But as the core gets more compressed, it also gets hotter. This additional heat and density kicks off a new round of fusion, which turns explosive: And the star itself gets unstable. The new fusion overwhelms the cohesive gravity formerly keeping the star intact, obliterating it in a massive explosion we call a supernova. It does so by overwhelming the forces of gravity."
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749f4m | Why do PCs make a beeping sound whenever you press 3 or more keys down? | Technology | explainlikeimfive | {
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"> Why do PCs make a beeping sound whenever you press 3 or more keys down? A standard keyboard saves cost by not having individual wires connected to every key but instead conveying a key press as a combination of several signals. To picture how this can work imagine a grid of wires 5 to a side. Now with sampling only ten wires you can detect which of 25 possible intersections are being triggered. The particular way in which those simple keyboards are set up is such that pressing three or more keys cannot be distinguished into the specific keys being pressed; there is ambiguity in what is happening and the computer sounds the beep to warn the user that their input isn't acceptable. Gaming keyboards are set up to prevent this event and many can handle any number of simultaneous key presses which would avoid the beeping.",
"Also I've always wanted to know does it have its own speaker for the beeping? It doesn't come out of my main speakers."
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749j61 | Why is it not enough to will myself to be stronger/faster? | Why do I need to exert external force on my body (like weight lifting) to make my body change in a way which it could have done on it's own? | Biology | explainlikeimfive | {
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"dnwitpi",
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"Because having bigger muscles means your body needs more energy intake to function. Therefore, your body wants to keep them as small as possible. When you lift weights, you're basically telling your body that you have heavy shit you need to lift, so it needs to make your muscles bigger.",
"Your body responds to stimuli. You can't, mostly, will your heart to beat faster. It does because something acts on it to work that way. The same goes for muscle. You can't just ask your body to produce more muscle fibers because you want them. The body knows the output of energy you routinely use and aims to be at maximum efficiency for that set of stimuli. Having a ton of muscle mass and not using it wouldn't be very efficient for your body, so there's no way to override that system (in general, broad strokes terms)."
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74a8iy | why does Greenland never have data? | Other | explainlikeimfive | {
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"text": [
"There are only about 56,000 people in Greenland. It is probably excluded because the sample size would be too low to be worthwhile."
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74aiqq | Why are members of congress allowed to accept money from organizations such as the NRA? | Other | explainlikeimfive | {
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"dnws40h",
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"Still- I do not think it is the NRA money that gives the NRA power, but the solidarity of their voting block",
"The people who make laws are Congressman. Why would they make a law that inhibits their ability to make money? They're also the people who make laws regarding their own salaries, and can vote to raise their pay."
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74alwt | Why do electronics which have gotten wet, stop working even when they completely dry? | Technology | explainlikeimfive | {
"a_id": [
"dnwsq09",
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"text": [
"In addition to the damage being done on contact (i.e. creating short circuits leading to immediate or near-immediate failure); tap water, rain/flood water, etc contain a lot of impurities. The evaporated water leaves these behind which may create a delayed onset of corrosion, which can cause poor contact between components and connectors. Distilled water is actually safe for most printed circuit boards (at least those with sealed components) as long as it is applied and completely dried before power is given to the device.",
"Water conducts electricity, so if a device gets wet, it can short out and destroy some components. It's like wiring every component to every other component. Bad news. Only one component in an important pathway has to die for the device to stop working."
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74aqnr | Are there planets in interstellar/intergalactic space? | So, here's where I'm going with this. As I understand it, when a solar system is formed, dust turns into clumps, clumps turn into bigger clumps and so on until the sun and planets are formed. There's also a lot of collisions. Could a planet size object (or bigger) get knocked into interstellar space or intergalactic space? I may be using the wrong terminology here.. I mean the space between solar systems and the space between galaxies. If so, is it possible to detect one (or have we done that already)? Lastly, (assuming this possible) with no sun, could there be life on them (for example, I've heard it's possible one of the moons around Jupiter could have liquid water because Jupiter's gravity is "flexing" it, or could the planet itself simply have a hot enough molten core for liquid water)? -Thanks! | Physics | explainlikeimfive | {
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"Yes, and quite a few. It is not uncommon for planetary bodies to get a gravity assisted slingshot out of orbit of their star. There are even brown dwarfs and other dark stellar-mass bodies floating around interstellar space (think binary stars where one gets flung). edit: They are known as Rogue Planets, here's the wikipedia: URL_0",
"One of the hypothesis for dark matter is the existence of massive compact object lying in the interstellar medium such as planet. See URL_0 However, astronomer looked for them and found out that if there is some there are not enough to be a significant part of dark matter (This is an example of experiment discovering nothing but contributing to the progress of science by excluding an option)"
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74au7a | How come whenever I have an in-person interview (no second chances), I do fine, but whenever I have to record myself answering questions (unlimited chances), I constantly mess up? | Other | explainlikeimfive | {
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"As someone who records himself talking nearly weekly & presents live as well... ...you're messing up when you talk live too. You just don't notice it and neither does your audience. People have different standards for live vs recorded, **and** since the recorded version can be reviewed, it's easier to hear mistakes. You can't exactly play yourself back in real life, can you?"
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74b09m | Why do some drugs exist in both pill form and liquid, but only the liquid needs to be refrigerated? | Chemistry | explainlikeimfive | {
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"text": [
"Drugs in liquid form have more opportunity to chemically degrade than drugs in pill form. Refrigeration slows any chemical reactions down. They could also become colonized by mold or bacteria, and refrigeration slows the growth of microorganisms."
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74b11b | Why does traveling to new places generally make people happy? | Other | explainlikeimfive | {
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"text": [
"1. Humans have an instinctive desire to explore. Following our instincts feels good. 2. It distracts us from our usual daily concerns, which aren't visible there. 3. We don't have so many chores or work to do when on vacation."
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74b1np | Why haven't all all prey who travel in flocks (eg; buffalos) just learned to attack the predator (eg: tiger) all at once and kill it instead of running away? | Biology | explainlikeimfive | {
"a_id": [
"dnwv9yf"
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"text": [
"Individual preservation instinct. The aggression tactic will almost guarantee that not all of them will make it. Same reason people can't generally mob and overpower an attacker en masse unless they are all soldiers or otherwise trained to do so."
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74bbl5 | Why do websites require complex passwords when anyone trying to brute-force guess your password would get locked out after a few failed attempts? | Technology | explainlikeimfive | {
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"You usually dont brute force the website. You use a security hole to steal the hash database and bruteforce that. There you have as many attemepts as you like.",
"Because early data breeches have shown that when passwords aren't complex people all tend to use the same few passwords. All a hacker has to do is try the top few passwords on all of the accounts until they get locked out and have access to the majority of the accounts. Password complexity is an attempt at forcing you to be unique.",
"In the old days, when you created a user account you would ask the user to choose a username and a password. You'd simply store those two things, and whenever the user wanted to log in you'd just look up the username in your database, compare the password they entered to the one set for that username, and let that user log in if the password matched. There were two problems with this. The first one is that anyone who had access to your database could simply look up user passwords, and log in as those users. You'd have no way of knowing. The other problem is, someone could gain unauthorized access to your system and obtain the entire database of usernames and passwords, and then they'd know exactly what to type in to login as anyone. Okay, so that's no good. What to do? Someone had an idea—when a user creates an account, let's not store the password. Instead, let's encrypt the password using a particular technique called a *one-way hashing function*. Sounds complicated, but it's really not. All it means is that you jumble up the password the user entered in such a way that you can't undo it to get back to the original password. For example, let's think about numbers for a minute. If you give me a method of \"encryption\" where, say, you take my number and multiply by 3 and add 5, if I choose a number like 15, then you store 50 (3\\*15 + 5). The problem with this method is that if someone gets the database and sees 50 next to my name, they'd type that in and it would fail. But, since they have access to my system, they can go through it and see what method I use. Once they know that, they can simply subtract 5 then divide by 3 to undo the operation, then log in with 15. This is *not* a one-way hashing function. Instead, what you could do if you're clever, though, is encourage me to choose some big number, and then divide it by something, and take the remainder. Look how this works: if I choose, say 13,456,994 as my number, and you divide by 145, you get 92,806 remainder 124. You store only the 124, though. Next time I log in, as long as the number I put in gives a remainder of 124 when divided by 145, you let me in. The bad guy doesn't know what I'm putting in, though. Ah, but they could figure out that all they have to do is put in some number that gives the same remainder when divided by 145—good point. So you also keep the average of the digits in addition to the remainder rounded down to the nearest whole number. Now the database stores a remainder of 124 and 5 as the average of the digits. Well this makes the problem a little harder for you to find a number that has a remainder of 124 as well as 5 as an average of the digits, but you could probably do it. But you see the point by now, right? So, a one-way hashing function is a function that produces an answer which can only be reversed into a particular input with a LOT of work. It's actually less work to just try to guess passwords, put them through the one-way hashing function, and see if they match. You could easily create an entire dictionary of common passwords based on the one-way hashing function I use, then just compare those to all of the encrypted values I've stored—you'll probably get a lot of matches, and each one is an account you can log in to. This is why sites force people to use special characters. The hope is that you'll be forced to take some kind of password you would have normally chosen that's in the bad guy's encrypted dictionary and modify it in such a way that it isn't in there. (Unfortunately, this is no longer a good approach. All of the modifications people typically make are now in the bad guy dictionary. For instance, if you would have used `password` as your password, but there's rules, you might instead choose `pa$$w0rd`. The bad guys know this, though, so they simply add more entries to their dictionary to include all these variants as well, the encrypted versions of: `passw0rd`, `pa$sword`, `pa$$word`, and so on.)",
"There's a couple reasons. First, let's consider someone thinking, \"well, SOME idiot is going to type \"password\" and submitting that as a password for every account on a site. No account gets locked out, since each only got one bad attempt. Second, consider data breaches. You might have a hashed and salted list get leaked, but if 14 people have the same salted hash, you know that's a weak password. You can then compare that to passwords/usernames in other breaches that leaked raw passwords, and you have a good guess on those accounts. It used to be a recommended best practice as well, and not a lot of sites have updated their policies since it changed. Currently best practice is to remove all password rules and compare chosen passwords against a bad password list."
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74bge7 | What is the psychology behind drivers who tailgate? | Biology | explainlikeimfive | {
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"If I get too close to you, then you are more likely to move away from me, ie, speed up. It's the grown up version of \"I'm not touching you!\""
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74bgix | How do we biologically "lose" energy as we age? | Biology | explainlikeimfive | {
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"You don't lose energy in the physical sense of energy. However as you get older your metabolism slows down, your muscles become weaker, your blood can become less capable of carrying oxygen, your joints become less lubricated, your bones become weaker, the list goes on and on. All of these factors combined help contribute to the loss of vitality seen in older individuals.",
"You don't lose energy, but your body becomes less efficient at everything. Your body is ultimately a biological super machine, but after decades of living you accumulate toxic substances in your organs, wear out joints and bones and the tiny 'mistakes' that your body makes when it repairs and renews it's cells accumulate. Exactly like an old cards vs new car."
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74blhl | Why do so many viruses have similar symptoms? | I was reading about how there are many different viruses that cause the common cold...why do all these viruses share the same symptoms? What makes a cold virus different from one that causes another viral infection? | Biology | explainlikeimfive | {
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"Different viruses can have a common tropism, i.e. the type of host cells they infect. In the case of the cold viruses they recognise the epithelial cells of the respiratory tract. Moreover, the symptoms are due to the body's immune response, rather than to the viral attack itself. That is why the body's response to a cold or to the flu are similar even though the sickness can be caused by totally different viruses.",
"The symptoms of a cold are your body's own immune response to a viral infection in your nasal passages, not anything the virus itself is doing. Most viruses that infect your nasal passages will elicit a similar response, just because that's how your immune system responds to viral infections there."
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74bsez | Why is it that we put ice on some injuries (e.g. black eyes) but want heat on others (e.g. sprains)? | Biology | explainlikeimfive | {
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"Because ice is used to reduce swelling while heat is used to bring more blood to the area. Bone injuries and muscle injuries also benefit from the different applications.",
"Yeah for sprains you're still going to want to use ice. For muscle strains heat can be used, but mostly you can't go wrong using ice on an injury."
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74bszs | Why were we tested on touching our fingers behind our back in physical education? | Biology | explainlikeimfive | {
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"It's a test of your flexibility. Flexibility is an important part of physical fitness because it helps to prevent injuries when you are doing physical activities."
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74bxmj | Why are companies removing the head phone jack? | The only reason I can think of is to sell wireless headphones, but I don't that's worth taking something away from the customer. I just want to know why. | Economics | explainlikeimfive | {
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"Well, luckily it actually isn't very widespread yet but here's the gist. Prior to computer created sound files or digital sound. Sound was recorded via analog. That means engineers used electronic or mechanical means to capture and transfer sound. These are called analog technology. For example, a tape player is *analog*. It plays back sound through mechanical means. Meanwhile, your computer plays *digital* sound. This is encoded data that the computer reads and translates into sound. Well, almost all the consumer wired headphones are *analog* technology. However, our phones and the music we play is obviously *digital*. That means phones need DACs installed in the phone. These are digital to analog converters. Compared to other cell phone parts, they are typically much larger and I presume there's a physical limitation to how small they can make them. Also DACs can have a significant effect on sound quality. It's like having someone interpret spanish to you that isn't very good vs a native speaker. Some things may get lost in translation sound wise with a bad DAC. Well the way to get significant space to make the phone smaller, and possibly conserve battery life would be to eliminate the DAC and headphone jack altogether. In addition, more phones are competing for Water resistant certifications. And the headphone jack presents a challenge because it needs to be able to conduct electricity yet, resist water damage. Lastly, less analog parts and less ports means less maintenance issues. One more port and the DAC means one more chance for something to put the phone out of commission. The downside though, is that digital headphones aren't prevelant and not nearly as cheap. Obviously, having sound go through same port as charging is not ideal. There isn't a standard that all manufacturers can agree on for digital headphones. This leaves Apple to charge a premium price for proprietary technology. Apple has a rich tradition of not clinging to tradition. If they see something that represents holding back future change, they don't mind dropping it. They also aren't nearly as afraid to require customers to buy proprietary technology because they have a business model that supports this dynamic with their customer. Plus their market segment does not include customers looking for the best bargain. That gives Apple alot of flexibility.",
"> I don't that's worth taking something away from the customer. The mistake you're making is thinking anyone gives a shit about the customer. You're 100% right. Removing the headphone jack forces people to replace the stock headphones with another $65 set of stock headphones rather than some $5 earbuds.",
"The headphone jack is fairly large, so it frees up room for other pieces. It's also apparently relatively susceptible to water damage. But yeah, it also sells new headphones, and Apple has a history of making old accessories obsolete. Consumers also seem to reward their change for changes' sake, to a degree. I'm not sure I'd say \"companies\", as it hasn't become widespread yet, and there are still some technical challenges. It's mostly just Apple, and a few companies copying Apple. the headphone jack is probably pretty safe until those tech issues get ironed out.",
"Allegedly, Apple did it to better protect against water damage / moisture. I assume other companies either did the same because of just that reason. URL_0",
"I got good enough wireless earphones on Amazon for $20, but I use them just for running. Using it all the time is a pain because they are easier for me to lose, forget to charge, and I have to fight with getting the audio to come out correctly because my phone likes my other Bluetooth Echo, TV speakers, car, etc. devices as well :/"
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74bxx8 | How does the common cold/flu get stronger every year and where does the 'flu' begin? | Biology | explainlikeimfive | {
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"It's not that it gets stronger every year, it's that the viruses evolve to a form that your immune system has never seen before, so you're vulnerable to it without a vaccination."
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74c0gg | If nuclear fallout is such a huge concern. How are nations able to test nuclear weapons within their borders. | If it's because it's done in remote places. Does that mean areas far away from major cities likely to be attacked are safe? | Other | explainlikeimfive | {
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"Nuclear fallout is very minimal from standard nuclear weapons, hence how people live in Hiroshima and Nagasaki just fine today. Nuclear tests will often be underground, underwater, or an airburst. The Japanese bombing was airbursts, which maximize destruction by create minimal fallout. Regardless, nuclear fallout is not a huge concern except in a full-scale nuclear war or reactor meltdowns. In that case, thousands of nuclear weapons would be dropped. It's not something that happens in any significant quantity from a single weapon. Chernobyl is an example of an instance that did cause consider nuclear fallout, and the reactor core is still humming away, buried in concrete underground.",
"Largely countries do their testing now underground, which limits the amount of fallout. Fallout is about radioactive particles getting into the atmosphere then falling back down. If you do your testing underground, there's not much fallout. There's still radiation, but then you just keep people away from those locations (hence doing it in the middle of nowhere, like deserts)",
"They used to do it out in the open, before they realized the full extent of the negative repercussions of nuclear fallout. So they used to test the bombs in the middle of the desert where there weren't many people around in the US. And the largest number of US tests were in the South Pacific, around the Bikini Atoll, using bombs many times more powerful than those used in Hiroshima and Nagasaki. At the time of the tests in the 1950s, the native inhabitants of the area were forced to leave by the US government, with the understanding that they'd be able to go back in a short while to their homes. However, they're STILL not back there because it's still radioactive. When it was realized how serious the damage caused by nuclear testing was, countries started doing their testing underground, so as not to pollute the atmosphere with more radiation. As for safety nowadays if major cities are attacked: it would certainly be safer there than it would be closer to the cities. However, it's been theorized that a large nuclear war involving many powerful weapons will cause major damage to the earth that will wipe out a large amount of life on the planet. It is hypothesized that it will cause \"nuclear winter\"--a worldwide cooling brought on by all the smoke and debris that are thrown up into the atmosphere by the bombs and prolonged fires afterwards. This will result in crop failures and death. There will also be a lot of radiation in the atmosphere that will pollute the earth and can cause sickness and mutations. So a true global thermonuclear war might end up killing most of life on earth.",
"Since 1963, a treaty has been in place that bans testing of nuclear weapons in space, air, ground, water - everywhere EXCEPT underground. Another treaty calling for a complete ban on testing was introduced in 1996, but has not been adopted yet by all parties. URL_0",
"So many very incorrect responses here. I was kind of afraid of opening this thread for this reason, but here goes... Fallout is a concern when you detonate nuclear weapons on the surface. Even small nuclear weapons can produce considerable contamination downwind. The Trinity shot of 1945, for example, [created quite a large plume]( URL_5 ). You wouldn't want to be someone who lived in that plume; close-in to the site, it could actually kill you or give you radiation sickness. Further out, it raises cancer rates. [The huge contaminating plumes from multi-megaton bombs]( URL_3 ) did contaminate the test sites they were set off in, and people did have to be evacuated, and many people who lived near the test sites did contract cancers, have higher rates of birth defects, etc. In the United States, people living due-east of the Nevada Test Site (e.g. in Utah) [did pick up significant levels of radiation from the drifting clouds]( URL_4 ). Individually this adds up to a small dose; over a large population this means an increase in cancers. Various estimates have been made by the number of people, worldwide, who got cancers from US nuclear testing. As one source concludes: > \"As a result of fallout from U.S. atmospheric testing between 1945 and 1963, an estimated 70,000 to 800,000 people in the United States and around the world have died or will die prematurely from a fatal cancer attributable to the testing (a comparable number of fatalities would be attributable to the Soviet testing program).\" This is from Arjun Makhijani and Stephen I. Schwartz, \"Victims of the Bomb,\" in Stephen I. Schwartz, ed., Atomic Audit, 395-431, on 395. The US has paid out [over $1 billion USD]( URL_1 ) to over 20,000 people who were \"downwind\" of the Nevada Test Site during the era of US atmospheric nuclear testing there (1948-1962), who themselves or their relatives came down with diseases attributable to fallout exposure. This probably _under_estimates the effects a bit but I just want to emphasize that the answer to your question is not \"they made it work perfectly safe and it wasn't a problem,\" the answer is, \"they exposed huge populations of people to radioactivity, and justified it by arguing that the safety of the nation was worth their collective sacrifice.\" After 1962 the US, USSR, and UK did all of their testing underground. China and France continued to test in the atmosphere for some time afterwards. Today nobody but North Korea has tested since the late 1990s, and so far they've been testing underground (but there are worries they may test in the atmosphere). As for a nuclear war scenario, it depends on what you assume \"the enemy\" will do. Nuclear attacks on cities are often presumed to be more or less fallout-free because the goal will be \"medium\" destruction and not \"heavy\" destruction and that tends to involve setting the bombs off high-enough that fallout doesn't occur. However if you imagine \"the enemy\" will attack US missile silos in the midwest, which are buried deep underground and are \"hards\" targets,\" then you are imagining a lot of surface burst weapons and that creates a lot of fallout. So fallout maps will vary by the assumptions you make (including about weather behavior). Here is an estimate [for the mid-1980s by Oak Ridge National Laboratory]( URL_2 ) — you can see that being downwind of cities, and of military bases, is a dangerous proposition. By comparison [here is one from the 1960s]( URL_0 ), which has more realistic weather patterns. \"Safe\" is always relative here. If you know how to take shelter from fallout and have shelter facilities available to you, in many cases you can be reasonably safe from it. The destruction of cities and infrastructure will have other impacts, of course, that will make life post-attack \"less safe\" (e.g., disrupting your food and energy supply)."
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74c0lo | What is this whole "Ayn Rand" stuff many people come across but "Thought it was cool at 15 but got over it by 21"? | Other | explainlikeimfive | {
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"Ayn Rand was an author whose major works (The Foutainhead, Atlas Shrugged) were largely focused on espousing her political views. Her political views consisted of something called \"objectivism\", which in its simplest form can be summarized as a kind of pure self-interest, and an opposition to anything which stopped the smartest and most capable from achieving the most they possibly could. Basically the view of Rapture in Bioshock (Ayn Rand's name can be found with \"Andrew Ryan\"). Low taxes, no welfare, lots of social darwinism. So, the part that 15-year-olds like is that she was very much against all forms of societal restriction on individuals. No drinking age, no drug laws, no taboos about sex, just... Do your thing. And it's appealing if you think you're going to be one of those awesome people whose hard work would be coopted by the government and the poor and all those less awesome than you who just want a free lunch. When you get older *most* people realize that (a) that kind of success is luck of the draw both for your own abilities and for whether you will be put in a situation to put them to good use, and (b) they probably benefited from some of those government programs which Rand was against. Many who believe they are self-made learn to appreciate that they really aren't.",
"tl;dr: Not everyone gets to be an astronaut. Ayn Rand wrote about her philosophy on life, which is called Objectivism. You will also here it called 'Rational Self Interest' as a simplification. Her idea was that society will function best when people are free to pursue their own happiness as best they are able, free from any limits of government. They will produce more, and better 'stuff' (in her books stuff can be everything from technology to hamburgers). Whatever free consenting adults want to do with themselves and each other is perfectly acceptable. Businesses do not need regulation, because if they produce a bad product or are harmful to society as a whole, people will not buy from them and the business will fail. It is in their self interest to act in a rational moral manner. Which sounds really good on paper. Two main problems though: 1: By the time you hit your mid twenties, most people realize that there is a huge problem with the \"rational\" part of the equation. You can be *wrong* about what is the best action for you as a person to take. Your situation may not allow you to take that action (ability, time, resources, etc). Her writing glosses over this. Anyone who is not a titan of industry is shown to be a noble worker doing their absolute best and helping move society along, while working to improve their station in life. But see the first line at the top. Toilets have to be cleaned, trash taken away. Not everyone gets to be an astronaut. When you become aware of that fact, the system looks a lot less fun. 2: A business is not a person. A person running a company may make a choice which benefits them, but destroys everyone else. They benefit, and are happy, so there is no issue under Objectivism. But when everyone does it, markets are not stable, and tend to crash a lot. It is not as efficient of a system. But you, usually, need some experience in the real world to see that. Or a formal education in philosophy, where you can analyse the system and see all of these faults, and more.",
"Ayn Rand paints a world where the elite are being held back because they have to carry the incompetent. When you are 15, that is a compelling message. Almost an adult, but still stuck doing what other people tell you. Naturally, you are one of the elite, but still have to do what the clueless adults say. Their ignorance is keeping you from reaching your true potential, and things will be so much better when you are free of them. Then around 25 (Rand is still pretty big with college students) you are on your own and discover life is kind of hard. Your band hasn't made it big, you big tech idea turned out to be lame and done before, and suddenly it isn't all about not being free to do what you want. And even if you are elite, you learn you also have to work real hard to make anything of that talent. You start think less of yourself as an undiscovered genius the world owes a living, and realizes not always getting to do what you want to is a big part of life as an adult."
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74c6hi | how/why can a person make different pitches/notes when they whistle? | How and why does whistling work? | Physics | explainlikeimfive | {
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"You change the shape and forward-/backness of your tongue (and occasionally other parts of your mouth but I'm not that fancy) to modulate pitch. This changes the distance the air has to vibrate in - like when you blow the tops of bottles and how you can change the pitch by having different levels of liquid in there."
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74caol | Why and how are there such insane amounts of energy released when splitting an atom? | And doesn't that mean we are surrounded by (and made of) even more insane amounts of energy? | Physics | explainlikeimfive | {
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"It takes huge amounts of energy (the kind found in the middle of a star) to squeeze protons together into a large atomic nucleus -- there is a huge repelling force that has to be overcome. Think of it as compressing an extremely strong spring. When you split this nucleus, you release this huge amount of stored energy. Yes, we are surrounded by and made of insane amounts of energy. In Einstein's famous equation E=mc^2 , c^2 is a stunningly large number."
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74ccz2 | How do ant colonies spring up overnight? | Biology | explainlikeimfive | {
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"Ant colonies are underground, and it times of draught or dryness, they will preffer to stay underground and collect moisture in the deeper, cooler layers of the earth. Once it becomes apparent to a colony that there's water and moisture above ground again, they will make it their business to become active above ground as well; there's more resources to be found there. Perhaps your area has experienced a long draught and the rain has caused all nearby ants to charge to the surface in droves. Ants as a garden animal bring pros and cons with them, but if you fear they might be damaging (due to their \"eternal supercolony\" size) to your garden, soil or potentially the foundation of your house , it's better to call in a friend who knows a thing or two about gardening, or a professional."
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74cj60 | Why is it so important for little kids to be able to colour inside the lines? | I always had such trouble doing this as a child and I was always reprimanded severely by teachers and by my mom. I was thinking about this because I still have trouble staying inside lines. | Biology | explainlikeimfive | {
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"It isn't super important that they donot all the time. It isnimportant that they have the capacity to do it as it is a demonstration and an exercise of fine motor control. It starts to build up the hand-eye coordination and brain-hand coordination thatnis going to be necessary for writing. It can also be a good exercise in patience and precision. That said, it absolutely isn't important that children are always inside the lines.",
"It deals with fine motor skills. It's not that they didn't want you to be creative but they need you to develop a certain proficiency to help make sure you're ready to continue your education further. Fine motor skills meant better handwriting, better dexterity for tasks and could be a marker for other needs or challenges later.",
"They are trying to teach you hand skills that will be useful when learning to write. They may also be trying to teach you the concept of following instructions."
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74d1l5 | Why don’t we get satisfaction from chewing and spitting out junk food? | Biology | explainlikeimfive | {
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"Chewing is a very rewarding activity - at least to our brain! It sends out hormones that food should be arriving shortly and sets your food metabolism in the works. Spitting out food after chewing gives you a hollow experience unless the food you were eating tasted awful (and even then, your body will still expect food). Also, we have knowledge that junk food is unhealthy for us, but for our simple biological insticts, food is food. Just because it's unhealthy on the long term, doesn't mean we get satisfaction out of wasting potential nutrients in the short term."
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74dbe8 | anyone know how to calculate how much force a car exerts on a human body when hitting a running pedestrian? | Physics | explainlikeimfive | {
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"Short answer, it is very difficult - there are lots and lots of variables at play, that you would have to model mathematically. This is one of the reasons that they still use crash test dummies and physical tests in the automotive industry. For collisions in general, the procedure usually relies in \"conservation of momentum.\" The assumption is that the total momentum (mv)1 + (mv)2 = m1m2*v1v2. For the case of a car hitting someone, this assumption does not hold though, as energy is expended in the permanent deformations that take place in both the car and pedestrian. If you made a whole bunch of simplifying assumptions (such as assuming the pedestrian was a rigid body, assuming an \"elastic collision,\" you might: 1. Calculate the change in velocity of the pedestrian though a momentum equation 2. Calculate the average acceleration the pedestrian would endure during the collision (this probably required an assumption of the duration of the collision, unless you are going to perform a very complicated dynamic finite element analysis). 3. Calculate the average force imparted to the pedestrian from F= ma Note that none of those assumptions are great though",
"Yes. we need more info, though. We need speed of pedestrian, Speed of car. Mass of pedestrian, Mass of car. Assuming its a horizontal collision perpendicular to gravity."
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74dbvq | if what were seeing when our eyes are open is a reflection of light, how are we "seeing" things when our eyes are shut, like when under hallucinogens for example? | Biology | explainlikeimfive | {
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"You aren't seeing light. It is covered to electrical signals that your brain interprets as 'seeing'. Closed-eye visuals are basically misfires on that electrical pathway."
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74du0k | why do animals in a fight suddenly take frequent, concerted casual breaks? | If you watch videos of animals fighting, you'll often see them go all out at each other for a couple seconds, and then suddenly stop and act is if the other didn't exist and they weren't in a dangerous situation. Everything we are taught not to do in a fight, like look away from the opponent or let our guard down, the animals will do. And then they will just suddenly start fighting really violently again, just to suddenly stop again and nonchalantly enjoy a view of the clouds or something, even if they may be right in each others' faces. Why is that? Do they just suddenly forget what situation they are in? And how do they know to start and stop at the same time? | Other | explainlikeimfive | {
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"Animals don't like to get hurt, because unlike humans most of them have shockingly low pain tolerance and can't really heal wounds well. So in most cases they fight briefly to make it clear to the opponent they aren't welcome. They keep it short so they reduce the chance of getting hurt, and will see if the opponent chooses to back off. If they don't they duke it out again until they either die or call it quits."
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74eczr | How do certain drugs cause you to see things in high detail that aren't actually there? | It's mindboggling to me. In one of my experiences, I saw little green dots covering one of my walls. I could walk up and touch each one and they never moved. It was as if I painted them there and could only see them under the influence. | Biology | explainlikeimfive | {
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"URL_0 Hallucinogens work by shutting down neurons that have the effect of calming other cells in the visual cortex (the bit of the brain that works out what you are seeing). So these cells start firing as if they are really dealing with real visual information. Human eyes are actually not that great and the brain has to do A LOT to make the partial information from the eye into a proper picture. Mess that with slightly and not only does weird stuff visual stuff happen, the brain acts as though it's all real."
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74elki | If cabin pressure during a flight is controlled, why do our ears do the thing? | Physics | explainlikeimfive | {
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"Cabin pressure is equalized at about 7000 feet it also changes slower than the actual speed of the ascent. So from 0-7000 and 7000-0 you still experience changes in pressure (but less quickly than if the cabin wasn't pressurized at all) Edit - [image I found while searching for the same thing a while back]( URL_0 )",
"Friend of mine flys a medical jet that keeps the pressure even lower, 2-3000ft I think. Then there are some outrageously expensive flights."
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74elyq | Why is is so difficult for us to do something when we wake up early and why do we lose the will to do it even though we though we were interested? | Other | explainlikeimfive | {
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"It sounds like there might be a lot of aspects in this, but I'll go for the biological angle. Sleep is, obviously, a period of non-activity for your body. It requires a grace period to reengage your metabolism; increasing bloodrate, consuming more nutrients, higher activity, etc. This all takes a while, and trying to kickstart your body into a faster metabolism requires the activation of hormones (like jogging a lap or drinking caffeine). Naturally, this puts you in a mood where you are simply focused on increasing your metabolism in a steady rate, instead of jumping into fun and/or intensive activities. Another angle is that, since you mention \"wake up early\", is that your sleep cycle got cut off. Your sleep cycle starts with lowering your metabolism and slowly increasing it back again; it's final stage is REM (Rapid Eye Movement) and waking up during or after REM gives you the 'freshest' start of a day. Waking up in any other part of the cycle means your body got interupted from precious resting and repair time and you will wake up very groggy, sleepy and will most definitely have no desire to go visit a themepark or take that jog."
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74f3zg | Why is it more difficult to detect/smell our own body odor? | Biology | explainlikeimfive | {
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"This has an evolutionary advantage as I read somewhere. Initially, you would smell your own body odor and the smell of the place you live in but within the next few days, you stop noticing the smell at all. This helps you identify if something or someone new had entered into your place of residence and thus alerting you to the danger that someone or something new at your place poses."
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74f5wu | Can LSD desensitize the receptors it binds to, thus causing biologically based mental problems, either tempory or permanent? | I have read that any agonist being administered repetitively to a receptor can desensitize them and since the desensitization of some receptors is sometimes linked to mental health problems such as depression and such, that's why I am asking edit: typo | Biology | explainlikeimfive | {
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"When LSD binds to the 5HT2A receptor(main receptor responsible for the psychoactive properties)((LSD binds on multiple receptors though)) the receptor acts as a lid and holds the molecule in place and the only way to remove the drug is by endocytosis of the receptor (This is why there is such a rapid tolerance to psychedelics) because it has to remove the receptor from the membrane to remove the drug then reinsert a fresh receptor later. As far as mental issues are concerned if you know you have a history of mental issues then the set and setting in which you take the drug could potentiate some of these issues, and i would probably say it would be best to avoid them all together unless you have really done your research and know what you are getting into. But i would say it has the ability to bring out underlying mental issues you may not even know you had. At the same time it can also be the most magical life changing experience of your life. LSD is a very curious molecule as your thoughts and experiences can vastly shape the outcome(which is some thing that does not happen with any other class of drug) The only long term effects worth noting would be that for some people with mutations in their 5HT2B receptor ( LSD is an agonist at this receptor) this can lead to heart valve issues with repeated dosing ( not just once or twice but multiple long term dosing). another long term outcome, from my experience is a general happiness about life and the ability to look past surface level bullshit and focus on YOU and understand what truly makes you happy.",
"With my very precursory knowledge of LSD, I do not believe it does. It doesn't bind to receptors like an opiate, the tolerance you build from a dose only lasts a few days. Shouldn't be any long term effects unless you experienced something traumatic or had such a great time you miss the fun and it makes you sad"
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74f7sk | What is a DDoS? | Technology | explainlikeimfive | {
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"Imagine a call center. It has a lot of phones to help ordinary customers. Most of the time only a portion of available phones are being used so everyone who calls in will likely be served. Now imagine you really dislike this call center, maybe you had horrible service once, maybe you are just a mean person. irregardless, you want to take down this call center. What you do is you get a thousand phones or a bunch of your friends that each have a few hundred phones to start calling the phone center. The phone center answers, and the caller doesn't really say anything, just keeps the employee in the center busy. While the employee is talking to you, he can't talk to actual legit customers. Have enough phones distracted doing nothing at once, and soon the call center won't be able to do what it is actually supposed to do: help people who actually have problems with their IT or what you have it. With every single phone operator busy trying to talk to your evil phones real customers are left to starve, and the phone center stops working. We've gone from everyone is getting served at this phone center, to nobody getting served. That's the basics of a DoS. You have a webserver somewhere being bombarded with so many fake requests that it can't respond to actual, legitimate requests, meaning the website or service the webserver is supposed to be providing comes crashing down and stops working. This causes immense financial damage to the company in question since it relies on that server being up and running constantly.",
"DoS mean Denial of Service. This a kind of Attack that have only one aim : consume all ressource a server can allocate to answer customer requests, by consuming thoses ressources you prevent the legit customer to access the service, enhance the name : denial of service. Typically the first DoS was working on network protocol level. When you open your browser and go to a web page, you send several request to the server, establishing a discussion between you and the server. A server have a limited number of ressource, so he can answer to a fixed number of customers (browsers). By sending a carefully crafted request, you basically use a ressource, preventing the server to use it for a legit customer. By sending a lot of request, you claim a lot of ressources from the server to answer your requests. In order for this to be effective, having only one computer setup to attack a server, mean that mostly you'll have less ressources in final (network bandwidth, open sessions,...) than the server you are attacking. So it is a form of DoS as you prevent some legit requests to be answered by the server, but this one is still able to somehow process a part of legit request. So to have a really effective DoS, you need to attack a server with several computers. Basically, you distribute the attack processus between several machines, that will attack the same server using the same method at the same time. This is called Distributed Denial of Service. The more computer you have to attack a service, the better is. As you can then rely on basic attacks instead of going on more complex ones. Currently, we see a move of the kind of DDoS from network DoS to application DoS. Before, you where trying to echaust network ressources, now it is more effective to exhaust backend ressources, such as the backend database, by asking the service to process heavy requests that take a long time to compute."
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74f8k4 | When connecting to a public Wi-Fi hotspot, why is it often necessary to try to go to an http://, and not an https://, webpage to get the sign-in screen to show up? | Often, when I attempt to access public Wi-Fi hotspots - in places such as coffee shop chains - that feature sign-in pages or require the user to click "I Agree" or "OK" to begin using the Wi-Fi, the sign-in page will not be triggered until I have typed in and attempted to visit an unsecured (http://) webpage. If I try to go to Reddit, Google, or any other page that uses an https:// protocol, the loading icon will simply rotate forever or until the request times out. Why can the sign-ins be triggered only by an http:// page? | Technology | explainlikeimfive | {
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"The sign up page works by directing your request for http:// URL_0 / to a server controlled by the wi fi provider. That server then responds pretending to be URL_0 , telling your browser to go to URL_2 instead. That works fine for HTTP, but with HTTPS the server has to provide a certificate proving that it's really URL_0 . Since the server doesn't have that certificate, your browser would know that it's talking to the wrong server and trigger scary security alerts instead of loading the sign up page.",
"The whole WiFi login screen is a hack whereby the WiFi service pretends to be any website you're visiting so it can present its login screen, even though you didn't try to visit the login screen. HTTPS requires a cryptographically signed certificate to prove that the site you're visiting is the site you think it is and, of course, the WiFi service doesn't have such a certificate. That's a major feature of HTTPS: stopping man-in-the-middle attacks. What the Wi-Fi service is doing is exactly a man-in-the-middle attack.",
"Usually the browser does a few extra check with https request, like being sure that you go on the page where you expect to go. If there is a login page the browser will raise an error thinking that the security is compromised (somehow it is since you don't go where you expect to)"
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74f9nn | Why do snipers need a 'spotter'? | Other | explainlikeimfive | {
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"I was an infantry sniper in the Army from around 2013-2016. We were supposed to run three man teams. Spotter, shooter, and security. This isn't what every sniper team runs. For example, I have no real idea what special operations do but I would imagine a two man team at least. -The spotter is the team leader and most senior on the team. His job is to provide guidance to the shooter. Generally in the form of walking the shooter onto target if not already there. Determining distance and giving an elevation hold, wind hold and hold for movement if applicable. After the shot it is important to watch for trace and impact to determine hit or miss. If there is a miss it is the spotters job to give a quick follow up call for the shooter. Simultaneously it is the shooters job to tell the spotter if they broke the shot clean or if they feel like the pulled directionally. The spotter also carries a long gun, usually something like a precision semi auto, but isn't the primary shooter. -The shooters job is to focus on the shots and as I said above to tell the spotter if they think their shot was their fault. -The security is basically your new guy. He is there to carry extra shit(ammo/batteries/radio maybe) and watch your back while you are both focused down range. TL;DR - Spotter is the leader and guides the shooter. Edit: Thanks for the gold! Trying to keep up in comments. Edit: I just want to be clear, I never deployed but I am sniper qualified and trained for the position. I'm not trying to take away from those who did. Any actual combat experience supersedes my experience. Also, I'm going back to school for civil engineering. So if anyone wants to hire me that would be awesome. Northern Colorado, pm me! Shameless plug I know... worth a shot!",
"Former army sniper here. There are several reasons you have a spotter. One is that ideally all the shooter should have to do is trigger pull, so you need someone to spot hits and give adjustment to get on target or where the next target is. The second is that rifle optics have a relatively narrow field of view compared to binoculars or a spotting scope, so the spotter has a better overall picture of what is going on. This also frees up the spotter to do secondary activities like calling up Intel reports and calling for fire. Finally you would never send a soldier into the field alone, so you may as well augment there abilities with some of similar skill set. Edit: an addendum to what I am seeing in the comments, the spotter is almost always the more experienced of the two, but not always the better shooter, as their emphasis is on target designation and quick correction which are skills developed over time. Edit 2: thanks for the gold trying to keep up with comments but at work",
"The military has an axiom: \"There is no such thing as an individual\" This underlies everything that is done. For example, the smallest unit in the Canadian Infantry is the Fire Team- for us that's a two soldier group. (the Fire Team is one half of an Assault Group, of which there are two in a Rifle Section...and on it goes upward) What this is intended to mean is that the welfare of the group is greater than the welfare of the individual- which might seem straightforward to some- but it is this group mentality which can be critical to success on the battlefield. There is a great deal of psychology and philosophy wrapped up in this concept. It is a very interesting thing to study because it can be both deeply indoctrinated and at times counter-intuitive. As far as snipers go, the top comment got this more or less correct. Very simply, two sets of eyes are better than one. That, and the art of sniping is far more than what it is often seen reduced to in popular media- look down a telescopic sight, put the crosshairs in between the eyes, pull trigger. The science involved in making or ensuring conditions for a successful shot, particularly at extreme ranges requires a great deal of complex calculations and using equipment that would require a solitary shooter to leave his firing position to work with. Marksmanship is a lot like getting a good golf swing. It is an entire body discipline. We use the acronym \"HABIT\" to teach the principles of marksmanship to each and every recruit: H Holding- a firm, controlled grasp of the weapon. The body of the shooter is to be imagines as a stabilizer, not unlike a bipod. A Aiming- pick a point of aim- centre of mass- and do not waver from it while engaging this target. B Breathing- particularly while lying flat in the prone position, the mere act of breathing will raise or lower the weapon's muzzle. Be conscious of breathing patterns, and always try to fire while holding a half exhaled breath (the pattern we teach is \"breath in-breathe out- breathe in-halfway out, hold-BANG-all the way out\") I Instinctive Positioning- this ties in to what I said above. From head to feet, the shooter must hold their position as still as possible. The slightest movement at the firing point will put the shot off. The further away the shooter is to target, the more a tiny fraction of movement can take a definite hit and create a wide miss. At the extreme ranges snipers operate, this is critical. T Trigger Control- even the way in which the trigger finger operates the weapon can create a nudge that would shift point of aim. A smooth, slow and fluid motion against the slack of the trigger is to be followed through in the same way. A quick snap on the trigger is called a \"jerk\" for a reason. So, those very basic concepts in \"HABIT\" is merely the foundation upon which the sniper is putting his shot together. Any information that they need or communication to their superiors beyond what can be done from a steadied firing position will be handled by the spotter.",
"Sniping (ideally) involves the development of range cards, sort of hand-drawn maps centered on the sniper's location, that is annotated with all sorts of information relevant to shooting. It typically is based on prominent features, things like a signpost, a turn in the road, etc. So in an engagement the spotter is typically reading off data from the range card while the shooter is looking at that through the scope or making adjustments to the settings on the scope's turrets (thus minimizing the amount of guesswork in aligning your crosshairs.) Spotters are also 'sanity checks' to confirm a sniper's assessment of distance, or math-check a calculation. They may be using a laser rangefinder while the sniper is engaged with the rifle. While a sniper can at one level just be 'some guy with a gun' - a well trained sniper team is able to adapt to dynamic and changing conditions and deliver first-round accuracy with much greater precision. I suppose it is like a pit crew: one guy could change tires and fill gas but an Indy500 crew can do all of it in a few seconds. Another important part of being a spotter is watching your own perimeter. If you have ever snuck up on a sniper in an FPS you realize how they become tunnel-visioned looking thru a scope. The spotter will typically have something more carbine-esque that is suitable for dealing with patrols or people who sneak up on snipers. Just a couple parts of the big picture, hope it helps.",
"Recoil from a high powered rifle (almost) always causes the sniper to temporarily lose sight of his target. By the time the he reacquires the target, the bullet has hit. If it was a miss, he has no way of knowing if he was high, low, left, or right. The spotter never loses sight of the target, and can tell the sniper what corrections he needs to make.",
"Snipers and spotters are in constant communication; the spotter is helping to find targets, range them (see how far away they are), come up with a firing solution (shooting at long range requires an adjustment of the scope, referred to as the DOPE, or Data of Previous Engagement, which is where your rounds hit from your zero on the range). The most important role of a spotter is to find the vapor trail of the round down range and relay the correction to the shooter in the event of a miss. You can actually see the air disturbed by a round going down range, and if your impact is off, being able to make that call and re-engage the target quickly is paramount in a combat situation. Say you are a mil left at 600m, the sniper can quickly account for that using the mil dots in the scope and shoot again before the target can flee. A spotter is also there to protect the sniper teams back while they are in their hide or providing over-watch for patrols and whatnot. You also aren't \"supposed\" to be on the scope for hours on end, and often the sniper team will trade off every so often so they don't develop eye fatigue when they are out on missions, which can be for days on end. The crap you see on TV is usually a terrible example, not only of how a sniper team works, but also their equipment, and marksmanship skills (the way they actually set up on the weapon, pull the trigger, and so on) *spelling",
"The spotter is most often the most skilled/seasoned of the two. Generally, the spotter, would range estimate and assist shooter (screwed a lot of people in school) where the shooters job is to just pull the trigger. Well, squeeeeeeeze the trigger. It all depends on the mission, etc.. Source: 4 years as an 11b in the US army. 2 of which with a B4 identifier.",
"The spotter's job is to see the big picture and relay information to the shooter. The field of view through a rifle scope is pretty small. Also the shooter won't see where the bullet strikes because the recoil will shift the gun off the target, so the spotter will give feedback on where the bullet hits vs where the aim point is. Good example here URL_0",
"As someone who works in and around this field I'll answer some of what I've seen. What is a Klick? Yes it is true that in most cases, it refers to a kilometer. BUT in this case a klick refers to the adjustments to the scope (most scopes will click as you adjust the sight up and down, left and right), often called a \"dope\". You'll hear shooters ask what \"dope\" they're shooting, referring to the corrections needed to account wind, angle, ammunition, temperature and other factors that effect bullet travel. In most real cases people don't refer to clicks but will refer to mill dots I side the scope. THIS ties into another role of a spotter, he is watching for the round to impact, and call for corrections, sending that to the shooter, \" half mil up, 1 mil right\". Once the corrections are made the spotter will let the shooter know that he is ready to observe the next shot and call more corrections if needed. You might ask why doesn't the shooter just watch his own rounds, but it is extremely hard to fire a rifle with the recoil and then get your focus back on target within milliseconds, so the spotter watches The role of the spotter? Yes a spotter provides security to a sniper, but in most cases, snipers aren't out just doing there own thing, most of the time they are attached to larger units to provide those units with recon. I was running a CP, (checkpoint) one day on the outskirts of a town. My attached sniper element saw a group of males exit onto a roof with RPGs and then duck back into the apartment building. They didnt need to shoot, but rather they let me know... and we went and paid them a visit, finding hundreds of weapons, night Vision and ammo.",
"Read about Carlos Hathcock. His nickname was White Feather. One of the best snipers ever. Vietnam war.",
"The shooter is focused on the target. If he misses, the spotter can see where the actual hit was and tell the sniper how to adjust his aim to get it on target. They also take turns observing prior to the shot since a lot of what snipers and spotters do is to gather intel and observe. They reduce eye fatigue this way. The spotter usually also carries a different weapon.",
"As oppose to some of the lame comments here I'll try to explain it to you as I've been a sniper for almost 4 years in the IDF. Basically - The sniper that shoots at the target won't be able to identify where he hit, or if he missed. The recoil from the shot (unless we're talking 22 .lr bullshit) moves the whole sniper rifle and you lose sight, but the spotter does not. He looks at the target from a different telescope that usually magnifies by more ( x40 ) and he tells the sniper where he hit. Even if the sniper hits, he needs another round to confirm the kill. The spotter will use a clock-like pattern to correct the sniper, e.g : miss, eight o'clock 2 mildots. That's when the sniper will correct to 2 o'clock, by the same amount of mildots. More reasons: - You need at least one more guy at a long ambush in order to do sleeping rotations - The spotter will be the primary target seeker - a lookout for the nearer areas. - another person to do the calculations. He'll tell the sniper how many clicks to move and/or measure the distance to the target.",
"Recoil can make it difficult to see where your bullets went. The spotter is typically the more experienced of the spotter-sniper team, as experience lends to more accurate adjustments. It's also easier to see [trace]( URL_0 ) as a spotter. The spotter will give adjustments to the sniper, and the sniper focuses on the mechanical function of shooting (breathing, trigger pull etc etc). Source: Yours truly, former Green Beret",
"I don’t know where people are getting the idea that a ‘spotter’ is a definite job within a sniper team. All snipers go through selection/training and then paired up, or assigned to a fire team/squad (terminologies are different for each countries military). Each one is the others ‘spotter’ and they switch freely, neither of them are the boss. The senior rank has nothing to do with who has which role, the spotter doesn’t command fire, and they don’t exclusively do the maths behind the shot, they’ll both complete the calculations and check against each other. If you want a better answer I’d go down to a recruitment office, or see if there are any open days near you.",
"Partly because while one man has his eye glued to a scope he is vulnerable to everything that isn't a fair way infront of him. So it helps to have a second there to provide more peripheral awareness. Secondly in some situations certain calculations need to be done to achieve an accurate shot. What's the wind like? What's the exact distance? etc. It's not very efficient for one guy to do all that a shoot at the same time. Thirdly, a spotter is useful in that they provide a second opinion. Two heads are better that one. Is it a good idea to shoot right now? Is this definitely the target? How exposed are we? What are the consequences of missing/hitting the target?",
"Next time you're at the range try doing a couple algebra problems whilst trying to hit your target.",
"So you don't get shiv'd in the back,...or a poison needle jabbed into you. And to spot the losers with noob tubes,while you spawn camp them bitches.",
"Spotters can inform the shooter of what corrections to make on the next shot. By viewing the target with a spotter scope, the spotter can see the air flow disturbance of the bullet path and splash when it hits or misses. Skip to the 3:00 mark to see the effect: URL_0",
"Yeah, so there's first focal plane reticles and second focal plane reticles. Someone can correct me if I have it backwards but ffp reticles scale with your zoom so it is still accurate for holds while second do not. Ffp reticles are more recent. We used the H58 on on the shooters rifle. Spotter generally had the TMR reticle and a mil-dot spotting scope.",
"The spotter works by, as previously stated, providing situational awareness. But during the actual shooting the spotter will also observe the target and relay any changes to be made with the optics (i.e changing the dials on the optics based on trajectory). Say that the shot lands just short or to the right of the target, the spotter will note where the bullet impacts and provide feedback to the shooter to adjust accordingly - since the shooter might miss where the bullet impacted. The spotter will usually also carry weapons more adapted to close quarter fighting - in case the sniper team is detected or attacked. The spotter is also usually the more experienced of the two, since they need to pretty much know all the calculations and differentials by heart. Source: I was a designated marksman in the army. Now mind you, this is not the US army, but I don't think the roles are that different based on country.",
"Generally speaking the spotter is the leader of the group though most decisions are in conjunction. He is on a spotting scope when the sniper fires looking for the vapor trail and impact of the bullet to make correction as the sniper is impacted by the recoil of the rifle. Spotters see the bigger picture and spend far less time on glass. They are generally equipped with closer range weaponry (assault rifles) to combat threats at closer range. Two people are often needed simply to watch the others back during periods of rest and to carry the mass equipment. When shots are about to me made the spotter is on coms with whomever is back at baseplate ensuring his shots are permissible. And finally the entire military revolves around the idea of a team. Battle buddies are a pretty hard and fast rule when doing almost anything in theater or stateside. For accountability and to maintain the team and brother hood mentality. No one is an individual.",
"I think it is also important to note that the main job of a sniper is to perform reconnaissance and provide specific information to the TOC (tactical operations command) and forces on the ground. The spotter can help by taking some of the load off of just the one other person with the elevation or distance advantage. As explained before, the spotter also facilitates with the difficult shots and doping (zeroing, ranging, and sighting in weapons.) Many times a sniper doesn't get a direct path up into a nest or shooting position. They often must traverse dangerous and rough terrain to get to their specific nest. The spotter will assist with identifying a possible nest position, movement to the nest, and securing the position from the angles that the sniper is not watching while he sets up. It's not easy to run and gun with a long barrel semi or single shot gun. We must also take a look at the specific operational force that we are discussing. The army, marine, and certain SO (special operators) often use spotters and teams to secure and provide overwatch. Some SOFs, however, do not use spotters. SEALs never use a spotter. They have a team that secures a position to provide overwatch and then moves to secure surrounding areas and call in certain orders. There is an old SEAL sniper saying, \"if you're there, you had better be shooting.\" I hope that someone reads this and it provides a thorough explanation. Thank you and have a hell of a day."
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74felb | Why are some plastics recyclable while others are not? | Chemistry | explainlikeimfive | {
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"Plastics are polymers - a fancy name for saying extremly, **extremly** long molecule with a repetitive structure. It's a blanket term for many types of different molecules, so not all plastics are the same. Recycling products is less of a \"is it possible\" and more of an \"is it economically viable\" question. One argument to be against recycling paper is that it's cheaper to simply produce new paper as opposed to devoting resources into cleaning and reusing old paper. The same goes with plastics. There are some very 'basic' plastics that have a molecular structure that make them very suspectible to chemical reactions and break them down, or have certain chemical properties that allow them to be chipped into bits and melted together into a sheet. The costs of recycling these plastics are cheap and abundant: a common chemical, a slicing machine, an oven, etc. Other plastics on the other hand, while in theory recycable, would require such extensive processing that they're simply not economically viable; they require very advanced machines or expensive chemicals to break down and rebuild their molecular structure."
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74fg9z | Why some people can't sing/whistle in tune and why is it so painful to listen to? | Hi, we all know people who love to whistle but they just can't seem to find the right pitch. Do they not hear it's wrong? Or perhaps they can hear but can't perform? Why is it? Also, why is it that listening to someone singing off pitch makes me want to pierce my ears? | Biology | explainlikeimfive | {
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"Some people have perfect pitch. I have to use a guitar tuner to tune my guitar. I could do it other ways but it would take longer. You obviously have pretty good pitch. That means you can detect the frequency of sounds well. Others cannot. But they probably have some rhythm which is a lot of music. So they do what they can. You are sensitive. So it hurts for you to hear off key music. Eventually I can tell my guitar chords do not sound good. So I retune. You would be more fussy."
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