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2tw19s | why when i have employer-sponsored insurance do i still have to pay for doctors and hospitals? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2tw19s/eli5_why_when_i_have_employersponsored_insurance/ | {
"a_id": [
"co2ti0t"
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"score": [
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"text": [
"Insurance doesn't cover 100% of coverage. You have deductibles & co-pays to prevent people from abusing the system & running into an ER every time they get a cold.\n\nMaking people pay a few bucks to use the service stops them from using it when they don't need it. This helps keep costs down for everyone."
]
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[]
] |
||
8k0a1p | - how common does a side effect have to be for a medication commercial to include it? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/8k0a1p/eli5_how_common_does_a_side_effect_have_to_be_for/ | {
"a_id": [
"dz3vc0s",
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"score": [
12,
2
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"text": [
"Test studies on humans are very very expensive, and any symptom experienced by any of the humans tested is listed as a possible side effect. Time and statistics lets your doctor know which of them you actually have to worry about.",
"Listen carefully, some of them have warning for things a drug hasn't ever actually done. \"It's thought it might cause PML, but theis has never happened.\"\n\nUs Law dictate they have to list a good bit, but the real motivation is avoiding having their buts sued off. by lawyers who fwill fire cases for people so dumb they get upset when a newer, safer, *blood thinner* still makes you bleed! (duh)\n\n\n\n\n\n\n"
]
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[],
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2jwmd3 | what were stephen hawkings greatest discoveries? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2jwmd3/eli5_what_were_stephen_hawkings_greatest/ | {
"a_id": [
"clfrv8c"
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"score": [
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"text": [
"\"Were?\" This made me think, 'Oh shit, he's dead,' and had to go check.\n\nHis branch is theoretical physics, which isn't really about 'discovery' as such. He and other theoretical physicists are all about bringing experimental and observed data from other branches of physics into the context of a wider framework. The supposed \"theory of everything.\" Some of the 20th century's favourite physicists have been theoretical physicists; Hawking, Einstein, Sagan, deGrasse Tyson. Theoretical physicists work at the bleeding edge of what we understand about the universe.\n\nHawking's work is mainly in astrophysics and general relativity, though he has branched out into quantum physics and particle physics as well. His greatest work is probably his book *A Brief History of Time*, which brought theoretical physics into mainstream culture for probably the first time since Einstein. In the book, he explained phenomenon like the space-time continuum and the speed of light in a way that casual readers and high-school level science students could understand, as well as mathematically proving the existence of black holes and dark matter for the first time. He theorised that black holes do emit radiation, previously thought impossible because of their gravitational pull, then he proved it in both mathematical and layman's terms. As he demystified theoretical physics, he furthered it.\n\nWhen he does eventually die, he won't be remembered for one stand-out discovery above all others, but for the body of his work as a whole. He has done as much to further the field of physics within his lifetime as Einstein, Newton, Copernicus, Aristotle... "
]
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[]
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||
ed0tt9 | why do many different languages that seem to not be connected share a rolled "r" | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/ed0tt9/eli5_why_do_many_different_languages_that_seem_to/ | {
"a_id": [
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"score": [
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"text": [
"Because it is a readily reproducible sound that can be made by most humans.\n\nI suppose another topic could be that the trill was a part of some proto-languages so some descendent languages inherited it.",
"One language is going to share a sound with another language, the rolled (trilled/tapped) r is effectively just a sound. What you’re asking is no different than asking why so many languages share the sound of ‘t’ even though they may seem dissimilar to each other",
"Rhotic R is more common than the non-rhotic equivalent; human languages share sounds as a rule, it’s the ones that are not shared that are the exception."
]
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[],
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||
50ba4i | good and bad cholesterol. | What makes good cholesterol different from bad cholesterol? How do they work within the body? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/50ba4i/eli5_good_and_bad_cholesterol/ | {
"a_id": [
"d72m4xd",
"d72os9s"
],
"score": [
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"text": [
"There is no good an bad cholesterol. There is just cholesterol and is an animal compound with the role in making the body as is cellulose in plants. It is produced by the liver from meat and fat you consume as well as from some kinds of mushrooms.\n\nCholesterol in the human body has a lot of functions; Helping with the digestion by creating bile and the creation of Vitamin A from Beta Carotene; It is turned by the skin into Vitamin D; it is used in the walls of cells; and in the creation of all hormones from the Steroid family.\n\nHowever, too much cholesterol tends to deposit itself along the blood vessels, leading to complications.\n",
"Ok, so what Thaos1 was saying is correct. Cholesterol is a fat. What carries this fat around our bodies is what most people think of when they say \"Cholesterol\". These are called lipoproteins. What they do is move the Cholesterol around your body. Bad cholesterol is big and sometimes gets stuck on the side of your arteries. Good cholesterol is smaller and doesn't get stuck, sometimes it even un-sticks bad cholesterol. "
]
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[],
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r64fw | how do movies/tv shows acquire rights for songs? | This is something I've always wondered. How are they allowed to play a famous song on a movie if its copyrighted? What exactly is the process? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/r64fw/how_do_moviestv_shows_acquire_rights_for_songs/ | {
"a_id": [
"c43ebop"
],
"score": [
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"text": [
"Basically someone owns the song, maybe the writer, or the studio, or the artist, or it could be someone who just happened to buy the rights to the song.\n\nRegardless, you go to the guy who owns the song and you ask them for permission to use it, and they tell you how much money they want in exchange for that right.\n\nYou pay them for a license to use the song, and that's about it. There might be stipulations around how you can use it and stuff, but in general it's just: you pay the owner of the song to let you use it."
]
} | [] | [] | [
[]
] |
|
4ddaps | what is 'shale oil', and how is it different than other types of oil? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/4ddaps/eli5what_is_shale_oil_and_how_is_it_different/ | {
"a_id": [
"d1pw10n"
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"text": [
"Oil that's found today is found in certain types of special rock formations. It's easy to get oil out of sand because oil and sand are still a liquid so a filter separates them. However, some oil is in shale which is more like a rock sponge. Unlike a sponge you can't squeeze it to get the liquid out. \n\nSo to get the oil out you need to break all the tiny spaces in the shale to create one big hole that allows a large amount of liquid oil to flow. \n\nThe oil in shale was mostly discovered long, long ago, but no one could get to the oil in ways that cost less than the oil (drilling an oil well is very expensive). \n\nRecently, we got better at angled drilling and can drill one well and extend holes in pinwheels away from the center and use a liquid to fracture an enormous amount of the shale around the well, which releases the oil trapped in it and allows it to be collected. "
]
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[]
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||
1paen3 | how come the united states has not tried to take over the world militarily, when all previous superpowers attempted to? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1paen3/eli5_how_come_the_united_states_has_not_tried_to/ | {
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"Far more profitable to exploit their cheap labor than take them over. Plus we'd piss off the global community, which would potentially lead to a large coalition of armies launching attacks on US soil. ",
"The United States realized that military occupation required significant resources, but \"free trade\" makes it possible to dominate people economically and to gain their resources without the drawbacks.",
"May I introduce you to the 11 trillion military bases that the US has all over the world?"
]
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[],
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||
2olgu8 | in english, why do people say "i used to do something" to indicate an action that had continued to happen but stopped; the past tense of "use" is used to indicate a past action, but shouldn't the verb indicate a past tense of using? | Grammar Question | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2olgu8/eli5_in_english_why_do_people_say_i_used_to_do/ | {
"a_id": [
"cmoab56"
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"score": [
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"text": [
"I'm not 100% sure what you're asking, but it's simply another definition of the word \"use\" - to do something habitually. Today you only find it in the past tense, but you'll find it done in the present tense if you go back far enough, like in Shakespeare:\n\n > CADE: Let me alone. Dost thou use to write thy name? or\n\thast thou a mark to thyself, like an honest\n\tplain-dealing man?\n\n > CLERK: Sir, I thank God, I have been so well brought up\n\tthat I can write my name.\n\nThe clerk habitually writes his own name, and that hasn't stopped yet.\n\nNot sure why the present tense version died out, although the fact that \"use to\" and \"used to\" sound basically identical might have been an issue."
]
} | [] | [] | [
[]
] |
|
38zyrq | why does baking soda have seemingly endless uses? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/38zyrq/eli5_why_does_baking_soda_have_seemingly_endless/ | {
"a_id": [
"crz7qes"
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"score": [
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"text": [
"Baking soda, or sodium bicarbonate, is useful because it's a weak base (in chemistry terms) that won't harm a human being. Whenever we need a weak basic chemical, it's easy to turn to baking soda. Furthermore, it's also reliably found in most homes, so it's easy to find as well."
]
} | [] | [] | [
[]
] |
||
3i4crc | what would happen if co2 levels became "too low" in the atmosphere? | The increase of CO2 levels and their contribution to global warming and their effects are widely known ideas. But what would happen if CO2 levels decrease beyond what would be considered as "normal" threshold | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/3i4crc/eli5_what_would_happen_if_co2_levels_became_too/ | {
"a_id": [
"cud6bmn",
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"score": [
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2
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"text": [
"CO2 is a greenhouse gas which traps heat from the sun within the earth's atmosphere. If CO2 levels decreased enough, more heat would escape into space, thus the world would start to cool. If it weren't for CO2, the earth would be a big ice ball.",
"This may happen in the far future (600-800 million years from now). CO2 levels naturally fall via weathering and CO2 is naturally emitted from volcanoes. Without people around these two are in a pretty nice balance. But in the future plate tectonics will stop and the volcanoes will stop emitting CO2 and weathering will bring CO2 levels way down. \n\nSo when this happens \n\n > Subsequently\n, \nWorsley & Nance (1989) \nhad \npointed \nout \nthat \n≈\n150 \nppm\napplied \nto\nplants \nwith \na \ntype \nof \nmetabolism \nknown \nas \nC3\n(the \nfirst \nstable \nproduct \nof \nphotosynthesis \nis \na \nthree\ncarbon \nmolecule, \nwhilst \nfor \nplants \nwith \nC4\nmetabolism \nthe \nfirst \nstable \nproduct \nof \nphotosynthesis \nis\na \nfour \ncarbon \nmolecule) \ncan \nhave \nvery \nmuch \nlower \nCO2\ncompensation \npoints. \n(Note \nthat \nmost\nforest trees use C3\n metabolism)\n\n_URL_0_\n\nSo basically when CO2 falls below 150 ppm, the plants starve because they can't extract enough CO2 from the atmosphere to make sugars. The plants die and then the animals soon follow."
]
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[],
[
"http://arxiv.org/ftp/arxiv/papers/0912/0912.2482.pdf"
]
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dep2ib | can food really affect human emotions, like being energetic or dull? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/dep2ib/eli5_can_food_really_affect_human_emotions_like/ | {
"a_id": [
"f2xo5dn"
],
"score": [
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"text": [
"Energetic and dull aren’t emotions really but does food affect energy levels and mood in general? It absolutely does! Too much of simple and refined carbs is like taking a shot of glucose. While it gives you a momentary burst of energy it eventually leads to a dip, that causes one to feel tired and dull. The body, however, takes time to break down protein and complex carbs, so it’s more of a slow release of glucose into the blood stream. This is the reason why doctors advise you to consume less refined carbohydrates. It is also important to remember that overtime, unhealthy and unbalance food consumption does not only lead to serious deficiencies but can impact your overall mood as well. Too much of anything is not good. The key is balance!"
]
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[]
] |
||
4biwtz | how does reserve indicator in the gas tank exactly work? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/4biwtz/eli5_how_does_reserve_indicator_in_the_gas_tank/ | {
"a_id": [
"d19k6lf"
],
"score": [
2
],
"text": [
"There is a lever inside your gas tank, with a float attached to one end. As you use up gas, the level goes down, the float goes down with it, and the angle of the lever is used to tell your dashboard indicator how much is left. "
]
} | [] | [] | [
[]
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||
vgwr8 | kim dotcom/ megaupload case. how the us was able to go after him, and whether or not he will win. | I can grok the basics of this whole thing, but the majority of it eludes me. Someone explain it to me in a way that can help me understand what exactly is going down? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/vgwr8/eli5_kim_dotcom_megaupload_case_how_the_us_was/ | {
"a_id": [
"c54godr"
],
"score": [
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"text": [
"New Zealand has reciprocal extradition agreements with many countries; you send back murder suspects for us to put on trial here, and we'll do the same for you.\n\nThe US don't have to prove guilt, just prove they want to try him in the US. That forced NZ to arrest him, to honour the extradition treaty. Now the US has to prove there could be a criminal charge for action based in the US, not just a civil trial. So the alleged crime is conspiracy, not piracy, and allegedly the crime occurred on some servers located in Virginia, USA. \n\nIn effect he's been punished by having all his possessions seized, without trial, because the US can exploit the extradition law."
]
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[]
] |
|
6dz3n0 | how does a horror movie scare everyone in general, when each people are afraid of different things? | Not everyone is scared of ghosts or zombies | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/6dz3n0/eli5how_does_a_horror_movie_scare_everyone_in/ | {
"a_id": [
"di6fvlc",
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"text": [
" > Not everyone is scared of ghosts or zombies\n\nYou're right. And the people who aren't scared of zombies don't feel (as much) horror from them as people who are terrified of zombies.\n\nBut *everyone* is afraid of being eaten alive - or worse, being bitten and then slowly losing control of themselves and *becoming* a zombie - because these are very natural innate fears that is core to being a person in general. So a horror movie will tap into those primal, natural fears as much as possible in order to evoke the horror response even in people who aren't *specifically* afraid of zombies or whatever other plot contrivance there is.",
"Because most horror movies present a good and frightening concept, but instead only deliver loud jumpscares during quiet moments, or ridiculous amounts of blood to gross people out.\n\nIts disappointing and predictable."
]
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[],
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|
ci3ubk | why can youtubers like scottthewoz use music that is licensed in their outros? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/ci3ubk/eli5_why_can_youtubers_like_scottthewoz_use_music/ | {
"a_id": [
"ev19xyh"
],
"score": [
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],
"text": [
"Found another more precise answer\n\nNowadays, most professional composers resort to AdRev or similar services to protect their copyright. Don’t let this discourage you. AdRev system allows the composers to easily clear the claims and even to whitelist entire YouTube channels to prevent any future claims\n\nSource: SafeMusicList"
]
} | [] | [] | [
[]
] |
||
4wdsb2 | there's been a lot of talk about a certain presidential candidate having his "finger" on the "nuclear weapons" button. is it really that simple? can the president just order a nuclear strike? what is the protocol? | It seems like wayyy too much power for one person to have the ability to just wake up in the middle of the night and bomb whatever country for a laugh, if they felt like it. Is there a system of checks and balances? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/4wdsb2/eli5theres_been_a_lot_of_talk_about_a_certain/ | {
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"text": [
"According to this Wikipedia article the Secretary of Defense has to agree also. If they don't the President can fire them and pick another one til they get someone who does.\n\n > While the President does have unilateral authority as commander-in-chief to order that nuclear weapons be used for any reason at any time, the actual procedures and technical systems in place for authorizing the execution of a launch order requires a secondary confirmation under atwo-man rule, as the President's order is subject to secondary confirmation by the Secretary of Defense.[citation needed] If the Secretary of Defense does not concur, then the President may in his sole discretion fire the Secretary. The Secretary of Defense has legal authority to approve the order, but cannot veto it.\n\n[Source](_URL_0_)",
"The Secretary of Defense is selected by the President who can fire him at any time and replace him with another of his choosing.\n\nOur President is also in charge of drone strikes and cruise missiles. Bill Clinton ordered a cruise missile strike on Osama Bin Laden after the first time he tried to destroy the twin towers.",
"Technically, yes. The President of the US is the commander in chief of the US military, and thus if POTUS issues an order to the military then--by the law of the land--the military should obey. Moreover, the nuclear launch system is designed more for speed and security than trying to determine whether a launch is in keeping with good policy. In a worst case scenario, the President will have ~30 minutes or less between when they get word that missiles have been launched, and when those warheads will hit their targets. In that time, the President must determine what the US will do, and it must be done quickly. There'd be no time to call Congress together and have them vote on what the US should do. By the time most of them could be contacted, it might already be too late. \n\nAs such, people lower in the chain of command are supposed follow their orders. After all, they have no way of knowing whether they're being ordered to launch because there's 200 megatons of nuclear warheads arcing towards the US, or if the President is off their rocker. That's not for them to decide. There is a reason the President of the United States is called 'the most powerful man in the world'. As Commander in Chief of the US military, the President wields an awesome power. \n\nHowever, there are lots of security steps that must be followed. One of the most important is the 'Rule of Two'. Essentially, under the Rule of Two, the President's order must be confirmed by another member of the government--usually the Secretary of Defense. Moreover, US military personnel are supposed to disobey an 'illegal' order, so some may refuse to obey the order to launch, if they think it's because the President's gone kooky. \n\nThankfully, we have no idea what will happen if the President wakes up one night, calls for the nuclear football, and issues the order to launch. Its never happened before, and hopefully it will never happen. By law alone, if the President order's a strike, then there's no one to counteract them. However, there procedures in place that should *hopefully* stop a \"I never liked Beijing. Thought it was ugly as hell. Let's nuke it\" moment. Hopefully, someone would be able to talk the President out of it, or otherwise keep the order from actually being given. Let's hope we never find out. "
]
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"https://en.m.wikipedia.org/wiki/National_Command_Authority"
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76hwi3 | why do our minds wander off so much and is this a bad thing? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/76hwi3/eli5_why_do_our_minds_wander_off_so_much_and_is/ | {
"a_id": [
"doeheqz"
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"text": [
"Being able to focus on one task for a long time is a skill you have to learn and practise. This is just like how lifting heavy things, running fast, remembering things better, reading faster, etc. can all be trained. \n\nIt's only bad if it's hampering you in your daily life. If so, you should try to practise staying focused for a longer period of time. Identify what tends to cause your mind to wander, and see what you can do to prevent it. "
]
} | [] | [] | [
[]
] |
||
4doqj2 | if hiv has a 0.11 chance (if circumcised) and 0.62% chance (if not circumcised) of being contracted through sex, why is it such a massive epidemic (at least in western nations)? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/4doqj2/eli5_if_hiv_has_a_011_chance_if_circumcised_and/ | {
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"text": [
"Because some people have sex a large number of times.\n\nAlso, because some people use intravenous drugs and reuse the unsterilized needles.",
"Because that is not the full story.\n\nMany people contract AIDS when they are the receptive partner in sex. For anal, the chance of contracting AIDS as the receptive partner is 1,4%, for vaginal it is 0,08%.\n\nThen, of course, there is the risk of contracting AIDS through the sharing of needles which can be as high as 2,4% per incident. ",
"First off circumcision is only the \"norm\" ( > 20% of male population) in the following countries (of Europe and the Americas):\n\n* Albania\n* Australia\n* Bosnia\n* Canada\n* USA\n\n(Source: _URL_0_)\n\nSecondly there is no conclusive date which supports this Hypothesis: \"A meta-analysis of data from fifteen observational studies of men who have sex with men found \"insufficient evidence that male circumcision protects against HIV infection or other STIs.\"[7] The CDC concludes \"There are as yet no convincing data to help determine whether male circumcision will have any effect on HIV risk for men who engage in anal sex with either a female or male partner, as either the insertive or receptive partner.\" \n(Source: _URL_1_)\n\nEdit: Also see palcatraz post.",
"Because those figures are *per occurrence.* \n\nAs you'll remember from math class, repeated occurrences compound and create a higher total risk over a lifetime. \n\nAlso, maybe more importantly, the virus is most communicable before retroviral symptoms set in. This means that the odds you quote are drastically different depending on the exact circumstances. 0.11% merely expresses the estimated transmission risk in gross assuming no other information. It's a rough estimate at best. ",
"What I want to know is in what \"western nation\" is HIV a \"massive epidemic\"? Unless we're talking the 1980s before people understood HIV?"
]
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[],
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"https://en.wikipedia.org/wiki/Prevalence_of_circumcision",
"https://en.wikipedia.org/wiki/Circumcision_and_HIV"
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3lasks | why do some people have bad memories flood in while trying to fall asleep, and can't fall asleep? and why do others dream in the stage between asleep and awake? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/3lasks/eli5_why_do_some_people_have_bad_memories_flood/ | {
"a_id": [
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"text": [
"Not sure about the first question, but the second part is something that's always intrigued me - [Hypnagogia](_URL_0_) is the transitional between consciousness and sleep. It can come with all manners of fun phenomenon, from lucid dreaming, hallucinations, hearing sounds, sleep paralysis, etc. From what I remember an old Psych teacher telling us, everyone is legally insane during hypnagogia :)\n"
]
} | [] | [] | [
[
"https://en.wikipedia.org/wiki/Hypnagogia"
]
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||
bk8kmj | why is witnessing violence so much more traumatizing than hearing it or reading about it? | [deleted] | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/bk8kmj/eli5_why_is_witnessing_violence_so_much_more/ | {
"a_id": [
"emeqpe3",
"emergbo"
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13
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"text": [
"Because you're actually experiencing the visceral, real effect of it. Kinda like why fireworks and roller coasters are meh on video but people will wait for hours irl",
"Imagination is great, but it isn't primal.\n\nImagine that instead of reading about a fistfight or a mugging, you see a mugging - you get much more freaked out by being the bystander. But that's not because you're imagination is bad: it's because on a primal level, your brain knows the mugging is a threat.\n\nYour brain spends a *lot* of time keeping you safe, even when you aren't actively thinking about it. We evolved from animals, and a part of us is always on the lookout for danger. You can imagine a mugging going bad, sure, but it takes an effort.\n\nWhereas part of your brain is *constantly*, automatically imagining that mugging going bad. As soon as you're a witness to violence your body is already responding, pumping out adrenaline in case you have to fight, or you have to run.\n\nLong before you've even finished thinking the thought \"Oh, this looks bad\" your body is already re-routing your circulation to keep blood closer to your vital organs and away from the skin.\n\nEven if everything is fine afterwards, those effects last. You're still jittery. \n\nYou can (just about) turn your imagination on and off. You can't do that with the stuff your body does automatically, because it's there to keep you safe and you're not meant to turn it off unless you really know what you're doing."
]
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[],
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qz7jl | timeshares | So, are they scams, or can savvy people actually benefit from them? Who is actually making profit? Also, what are timeshare presentations exactly?
Basically, what is the deal with those timeshares? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/qz7jl/eli5_timeshares/ | {
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"Timeshares are essentially a property that is owned by several people, where each owner has a specific time each year that they have access to the property. It's great if you can afford it, want to/can go to the same place each year, and actually make use of it.\n\nTimeshare presentations, which is what it seems like you're asking about, are scenarios in which someone is compensated for going to a presentation by receiving a free vacation/accommodations/ what have you. Basically, you get some great free stuff, but you have to sit through the presentation (usually a half-day) and super high pressure sales pitch. This is actually how my parents did their honeymoon. ",
"Imagine you've been to Florida a few times, and you really enjoy it. Maybe you'd like to own a vacation home there, but you can't afford it, or it does not make sense for you to buy a home/condo if you would only use it a week or two a year. \n\nLet's say you can find 25 other people who are in a similar position: they'd each like to go to Florida for a week or two every year, but that's all. So, you all agree that if you pool your money, you can buy a beach house. Then, you divvy up the weeks, and everyone gets two weeks per year to have the house. What you own is the right to use the vacation house for two weeks every year.\n\nNow you can probably see some problems with arranging that, like how to get all 25 people to agree on the property, price, week divisions, etc. So, to solve that, a company takes control of the property. The company is now responsible for finding people to buy \"shares\" of the house. They are responsible for the upkeep of the house, too (but the \"share owners\" have to pay them a fee every year). \n\nCompanies that manage the time shares sell off \"shares\" and sometimes make a profit on the sales, sometimes not. But they do also charge annual fees for maintaining the property and managing it. On this, they make a boat load of money. Share owners might be forced to pay $500-$1000 a year for the fees. If they sell 25 \"shares\", thats $12,500 to $25,000 per unit that the company manages. (On average, it might only cost them $2-$5000 a year to maintain the properties). These fees are where the time share management companies make big bucks.\n\nTime shares are a good value if you intend to use it every year and you know that the fees are not that high. However, they often hide fees in fine print, or give promotional deals (\"No fees for 2 years\"). It is also extremely difficult to sell time shares, unless you give it back to the company and pay more fees.",
"My family used to sit through these presentations during the holidays so we could get free/cheaper park tickets (Orlando specifically). We'd sign up for the earliest appointment, and score a free continental breakfast. Tour consisted of about 45 minutes to an hour traveling to different scenes around the rooms and then end it with the high pressure sales pitch. \n\nWe became so accustomed to the routine of the presentation that my mom would always end saying she had just lost her job or credit debt. They would bring the final boss of the negotiators and he would offer a last deal option, and my parents would play into not being able to afford it and then they'd shove us out but not before giving us free multiple park passes. Probably valued at $110-100 plus bonus continental breakfast eggs :)",
"You can also buy timeshares on the resale market without sitting through one of those presentations. It's usually way cheaper because its just people selling their properties themselves instead of the corporation trying to take your money (who would also have to try to recoup the cost of getting you to the timeshare presentation). Also, I've found that renting timeshares is way cheaper than renting a hotel room for a week for the same reason. A person may not be able to utilize their timeshare week that year and just want to not take a loss on the maintenance fees. [This site](_URL_0_) is the one I've used a few times, but there are many others. Just watch out for sites that look kind of shady and scammy.",
"Ah, something I can explain!\n\nTimeshare means you are purchasing a \"share\" of a property. Sometimes this is a simple agreement among friends / business partners. For example...\n\n* I want to buy a house at the beach. I've got $150K saved up, but I can't qualify for a loan on a second home. I have four people in similar situations, so we decide to pool our resources. We each put in $150K for a total of $750K. That buys us a nice place, ocean front, at the beach. Costs are shared - insurance, taxes, etc. We agree to some sort of selection system, where maybe I want the house for two weeks in June and a month at Christmas... but Bob wants the house for three weeks in August (and so on, account for all weeks, everyone agrees to an equitable split). And maybe we rent it out a little at peak weeks, just to recoup some of the investment. If we die, our \"interest\" in that house is transferred to a spouse or child... or can we can sell the 1/5 share. We just make sure a lawyer creates a robust contract to protect us all.\n\nNow, that used to be more common... but it's a fairly rare thing to see now. But I want to use it as a simplistic example so when we talk about what timeshares *usually* look like, you've got a simpler reference. Here's how modern timeshares typically work:\n\n* You buy \"points\" with a timeshare company that owns many properties. Let's say for example that 100,000 points costs $10K (for simplicity), and your points are set to the establishment where you bought them (i.e. the company owns multiple properties, but you have a \"home\" property for those points). Let's say you bought the points at the Aspen, CO time share office, because you like to go skiing every February for a week. That costs 96,000 points to book, so (buying in blocks) you pay $10K to get 100,000 points (this means you get 100,000 points EACH YEAR - automatically), and that's enough points to get your week in Aspen every year. You pay upkeep charges on the unit too, might be $1,000 per year. Ok, so you're set, one week in Aspen for the rest of your life (not a set week, you still need to schedule it far in advance)... you bought in at $10K (which you can sell back at some point) plus a $1K annual fee to maintain the unit. When you visit Aspen, you need to pre-arrange the week you're going well in advance, and you do not have a set unit.\n\n* Let's say you don't feel like skiing this year... you could bank the points for next year, and go somewhere for TWO weeks! Or skip this year, and use the rollover points for somewhere nicer next year (a luxury unit in Hawaii for example). Or maybe you just want to trade, to take the kids to Disney. Easy, you call companies main office and tell them what you want to do. You're probably getting preferred status at your \"home\" office in Aspen, but it's a big company, lots of properties, assuming you're planning appropriately in advance and have enough points to do it - you can go anywhere they have properties.\n\nAlso, units can be \"rented\" to non-timeshare owners. This lets them fill up vacant units.\n\nA few other notes:\n\n* One way to \"game\" the system is to have your \"home\" property be somewhere with lower maintenance fees. Beachfront units in a hurricane region have WAY higher fees than a ski resort would. And a ski resort will be far higher than even a simple lake property in Montana. You run the risk of not getting preference where you *really* want to go (Florida) but you will probably be able to get a unit, and you still only pay your \"home\" unit's maintenance fee.\n\n* Usually we're talking about condo style units, NOT houses (with a big company). These just look like nice apartment complexes (outdoor covered entry usually, maybe a more \"hotel-like\" interior hall if it's a busier urban property or a converted hotel). Units can be 1-2 bedrooms, what I've seen most commonly is two bedrooms with a small kitchen and shared living room. Great for two couples, or parents with 2-3 kids.\n\n* Getting buyers is often a high-pressure sales pitch to a group. They offer guests (owners and non-owners) who are staying with them to visit a presentation... maybe a 1-2 hour pitch. And it's always entertaining and informative, but still, a sales pitch. They'll offer guest $100 or more (often in gift cards or reduced fees at checkout) for attending. Usually in a group of 20 couples, they'll get 2-3 seriously interested people, maybe 1 couple that buys on the spot (might just be an owner buying more points).\n\nMy personal experience is that if you like going to the same place every year... and you've stayed at a location and enjoy it... it can be wonderful. But if you are not confident in your ability to take annual vacations... or you're just the kind of person who prefers to go somewhere new every year... this is a horrible investment. Just very circumstantial to your personal preferences.",
"I used to work with a company that made \"anti-rescission\" videos and brochures for timeshare companies, or as they call it, the Vacation Ownership industry. They call it that because \"timeshare\" had gotten a seedy reputation, and rightfully so. Anyway, the videos and reading materials are meant to get you through the three-day rescission period, where in most states you can void whatever contract you signed due to buyer's remorse or coming to your senses, or what have you. They also produced all the materials you'd see at the presentations, full of lovely stock footage and crappy generic music, showing happy people twirling on beaches, riding horses, relaxing by the fireplace, etc. trying to get you past all the questions about \"what do you mean I own the week but not actually any equity? So I don't really own any property? You mean I have to pay fees on top of all that? I can't just pass it down to my heirs? Why can't I trade my week in Arkansas for a week in Zurich?\" and so on. It was interesting to work on variants of publications for states like Florida and Arizona (areas with large retired populations) that had very strict boilerplate legalese that had to appear on every item at a certain font size, like \"THIS IS NOT AN INVESTMENT\".\n\nAs some others pointed out, if you know what you're getting into, it can be a good thing. But if you wandered in off the street to a presentation at a strip mall to get a free MP3 player, the main beneficiaries are the sales person and the timeshare company.",
"They are often scammy, but not full on frauds.\n\nYou are buying the right to use a property for a limited number amount of time each year, usually a week or two, at some vacation destination. If you put your money down, this is exactly what you get. The scammy part is:\n\n* They are often sold in high pressure captive audience situations, like where you get a free vacation in exchange for sitting through a 3 hour presentation.\n* There are often a lot of hidden fees and taxes on top of the purchase price.\n* Unlike other real estate, they almost never appreciate in value, and are notoriously hard to sell.\n\nThey might be worth it if you *really* like the area, but for the most part you are better off with a hotel, where you aren't locked into taking the same vacation to the same place and the same time each year.\n\nAlso, since they are so hard to get rid of, there is a large secondary market...people will often sell their timeshare for a $1 just to get out from under the fees and taxes.\n\n"
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1heda6 | so germany is mad about the us spying. what options does it realistically have? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1heda6/eli5_so_germany_is_mad_about_the_us_spying_what/ | {
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"None. But since they've known fully well that the US (and the Brits, and the Russians, etc) have been spying on them now for about the past 75 years, I don't think they are really all that upset about it. It's just Germany playing their part in the game of international relations.\n\nEveryone stays relatively quiet about this stuff until it makes the news. Then the victims have to at least pretend to be upset. There's really nothing to see here, and nobody takes it very seriously. Including Germany.",
"Short answer: none.\n\nLong answer: none, unless they want to compromise their economy and global standings. Short of all of the NATO member nations banding together in a boycott against the U.S., it's diplomatic suicide to defy America; despite everything that the U.S. does wrong, it's still the leading political and military power in the world.\n\nPoliticians will give the press soundbites about how this is 'shocking', how it's 'unacceptable', etc., but this is all a performance for the public. The governments affected, be they Chinese, Russian or German, know that they have no real recourse; America is too powerful of an ally for them to do anything. \n\nNo matter what, the NSA will continue to spy. That's their function as a security agency, after all. Germany knows this; Russia knows this; China knows this. I'm sure their intelligence agencies have their ears to America's walls in return, anyway. That's the nature of our interconnected world - everyone is spying on everyone, even if they're best friends.\n\n(note that I don't agree with the practice at all, but I'm pragmatic about it - barring sustained, widespread social revolt in the United States, the government won't budge an inch)",
"Truth is that the German government isn't mad about it. They already know about it, and they're doing the same to us. The politicians are just milking this controversy for votes. By acting all mad at the US and telling the people that they're going to put a stop to it, they get reelected. Its all politics."
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8taxrs | how does einstein's equation explain the big bang? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/8taxrs/eli5_how_does_einsteins_equation_explain_the_big/ | {
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"It doesn't explain it. Einstein's field equations include a parameter in them called the \"cosmological constant\", which is the energy density of vacuum. Einstein included it in the model because otherwise the universe would collapse gravitationally, and this is what \"pushes back\" to balance it out.\n\nThe net result of this parameter being non-zero and within a certain threshold is that the universe will be expanding at an accelerating rate, not just perfectly balanced and static, as Einstein originally intended. This is the value we found in experiments that estimate the value of the cosmological constant.\n\nIf the universe is expanding, then if you reverse time you'd see it contracting. This would mean that at some point in time it must have been very small. The event which kickstarted this expansion, whatever it may be, is what we call the Big Bang.\n\nEinstein's theory doesn't predict the Big Bang by itself, as it says nothing about what value the cosmological constant should be. It only models its effects. It also doesn't explain the event itself. ",
"It does not. Einstein made some extremely important contributions to physics, but predicting the Big Bang was not among them."
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16uvev | (literally): "why are most american pro basketball players black, when most americans are white?" | How would you explain this to a 5-year-old? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/16uvev/eli5_literally_why_are_most_american_pro/ | {
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"Basketball courts are really common in a lot of cities because they're easy to build and don't take as much work as a park or other kind of playground. And you can play basketball even without a court if you have a hoop and some open space.\n\nBecause most cities have lots of concrete and not much grass, kids who want to play games usually have to find games that don't need grass to play on. Basketball is that kind of game.\n\nIn a lot of cities, some poorer areas of the city have more black people than white people. There's a lot of reasons for this that we can talk about another time.\n\nSo when you have lots of cities with lots of young black kids who have no other game to play than basketball, a lot of black kids grow up playing a LOT of basketball. Some of them get really really good at it.\n\nA lot of white kids play basketball too, and some of them get really really good at it. But a lot more white kids have access to games like soccer, baseball and football and may not play as much basketball, so they don't get as exposed to it while they're really young and develop the skills you need to be able to play as a professional.\n",
"No one really knows, but it likely due to one or more of these reasons:\n\n* Cultural - basketball is more popular in the black community, and more black youths are drawn to it\n* Demographic - blacks tend to live in urban areas, where basketball might be the only sport available\n* Economic - many blacks live in poor areas, and basketball is an inexpensive sport to get into\n* Aspirational - black youths in poor areas often see sports like basketball as their ticket out, and work harder at them\n* Genetic - there is some evidence of physiological evidence to suggest blacks are better at sports that involve explosive bursts, like sprinting or jumping"
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2f2eh3 | why do we sometimes see colors when coughing really hard? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2f2eh3/eli5_why_do_we_sometimes_see_colors_when_coughing/ | {
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"If you're talking about extremely small and obscure flashes or balls of static when we cough or sneeze, I'd assume that's when we put stress on the eyeball/connection(?) itself. \n\nHard to answer this without a bit more specification, could you provide more detail in your question? :)",
"I've read somewhere before that the light sensitive cells in our eyes are also pressure sensitive. A sneeze puts pressure through your sinus cavity resulting in triggering of light cells.",
"You might want to get that checked.",
"\"Seeing stars\" is a common visual complaint, but it is usually a normal and harmless occurrence. If you close your eyes and rub them, you will probably see spots and flashes of light. These images you see are called \"phosphenes,\" an entoptic phenomenon characterized by the experience of seeing light without having light actually enter the eye. Phosphenes are produced by pressure on the eye. This pressure is translated into various patterns by the optic nerve. Source: _URL_0_"
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b6y8um | when you're driving on the road whilst lost deep in thought, does the subconscious / muscle memory ensure you're driving properly? looking for an eli5 on this. | As per title, sometimes if I'm deep in thought while driving, I think my subconscious takes over and once I return back to reality, I'm somehow safe and sound as if I was driving normally. What causes this? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/b6y8um/eli5_when_youre_driving_on_the_road_whilst_lost/ | {
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"I think the best way to think about this is that your brain has multiple parts, and those parts can work on different problems simultaneously. These parts can be physically different regions of your brain or just different conceptually.\n\nIn addition to driving and thinking, you are also breathing and maintaining your position in the seat. You might also be chewing gum, Tapping your fingers in rhythm with music, and a variety of other things.\n\nThere is a part of your brain that is good at solving problems. But this part is not involved in normal driving. It'll get involved if it needs to be, and then you will not be able to be lost in deep through anymore. For example, if you miss a turn and need to plan a new route, then you must pause whatever other topic you were thinking about. If you approach a 4 way stop and are not sure whose turn it is, then the problem solving part of your brain must shift focus to decide whose turn it is. \n\nIf there is an accident in front of you, the problem solving part of your brain will shift focus, but it won't help you avoid the accident. it is much to slow. Your reflexes will help you avoid the accident and your higher reasoning will then start analyzing what happen.\n\nReflex training is important in many fields. In any fast occurring situation (military combat, sports, fast pace video games) training is important. Because problem solving thinking is too slow you need to train so that you can react appropriately in the different situations you encounter.\n\nThis is why its hard to drive in snow. If you start slipping you cannot think through a solution to stop slipping. You only have time to react. If you have no practice driving in snow, you won't react properly.",
"Your subconscious isn't driving the car for you, you still are. However, since nothing interesting is happening, your brain does not save the experience even into your short term memory, it just discards it completely. This is why you don't remember anything, not because you dozed off or lost consciousness."
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44jifj | what is the difference between the german and american healthcare systems? | From what I understand Germany has mandatory insurance like America, yet avoids all of the criticism of the American healthcare system. What's the difference? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/44jifj/eli5_what_is_the_difference_between_the_german/ | {
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"Germany has non-profit \"sickness funds\" that all employed people are automatically registered into. It's paid through by joint employee-employer contributions. The insurance providers cannot make profit off these general plans and must provide common rates for all members and cannot reject anyone. The rates and what is or isn't covered are bargained and negotiated by each German State. People who are unemployed or cannot afford it have it paid for by the municipality government through their welfare.\n\nThose who earn over 50,000 Euros may purchase private insurance.\n\nSo in general Germany's insurance system is highly regulated and built for universal coverage and the government actively engages in price negotiations and what services are offered in the package.",
" > What's the difference?\n\ni don't know much about the american system, but i can give a short rundown on the german one.\n\n > From what I understand Germany has mandatory insurance\n\nit's true that nearly all people in germany are insured, but germany does not have mandatory insurance for everyone. there is a law which states that all employed (up to a certain wage), unemployed benefits receivers, farmers, artists, disabled working in a sheltered workshop, students and pensioneers have to be insured, but that obviously isn't everyone in germany.\n\nwe have 2 kinds of health insurance, one is \"gesetzliche krankenversicherung\" (statutory health insurance), the other one is \"private krankenversicherung\" (private health insurance). the difference is that the statutory is highly regulated and mainly for those who i mentioned in the first paragraph, the private much less regulated and mainly for high wage earners, self-employed people and civil servants. in the recent years the law has been changed so that freelancers and small business owners can enter the statutory insurance system voluntarily (it's sometimes much cheaper). obviously, the vast majority of people are insured in the statutory system, at the moment there are 69.5 mio out of 81.5 mio germans insured there.\n\nthe private insurance is quite like what you would expect from an insurance: if you want to get a contract, they check your health, then they offer you a payment plan. payments rise if your risk for injury or sickness rises, for example if you get old. if you get sick, you go to the doc, get a bill and send it to your insurance. maybe they pay, maybe not.\n\nthe statutory insurance is different. at first there are no health checks, the payments are called \"beiträge\" (contributions) and are fixed by law. this is at the moment at 14,6% of your wage and split between employer and employee. however, the insurance is not a state-insurance, you're insured at one of 130-ish independent insurance companies (\"krankenkasse\") that may offer extra health services - which may result in an extra fee. the statutory insurance also includes spouses and children up to 23 (25 if still student) for free if they have no income on their own. \n\nthe drawback is that statutory insurances have only a limited range of services, which are also listed in a law. for example they pay for dentist visits and amalgam fillings, but not ceramic fillings (you have to pay ~50 euros extra per tooth), glasses are generally not paid, they also don't pay for orthodontics if your teeth aren't crooked more than a certain measure. it's also typical that statutory insured have to wait longer times (often months) for an appointment at eye or ENT specialist, while private insured get appointments within a few days. this lead to the term \"zweiklassenmedizin\" (two class medicine), which means that statutory insured only get second class medicine, while private insured get the good stuff. since both the range of services and the height of the contribution rate are fixed by law, balancing between the two is a big thing in german politics.\n\nyou also can't go to every physician, you're limited to physicians who are members of the \"kassenärztliche vereinigung\" (the vast majority of them are members, so this isn't really an issue). if you get sick you don't get a bill, but you just check in at the doctor with your insurance card, anything else is done between the physician, the kassenärztliche vereinigung and the insurance. in this matter the statutory insurance is quite care-free insurance.\n\nhowever, this dual insurance system is not without gaps. there are people without health insurance in germany, most of them could not afford their payments anymore and didn't make a new contract with another insurance company. especially private insurances can become quite expensive if you get old or happen to be in another high risk group. however, these people can't simply switch from one kind of insurance to another kind, they usually have to stay in the group of their last insurance. they also have to pay for the time that they were uninsured as soon as they make a new insurance contract. after the number of uninsured people peaked at 400'000 in 2007 the gouvernment made several attempts to reduce this number and in 2011 there were roughly 137'000 people in germany without any health insurance. that's less than 0.2 percent of the german population."
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5wdj1s | how we accurately accurately map segments of the human brain by sight during surgery. | I got on the topic of brain surgery with my co-workers (RNs). I asked for a simplified version of how, during surgery, we know what area controls what and exactly where these borders in the brain tissue are.
so hypothetically if there was an operable tumor on the part of the brain responsible for sight how would a surgeon know cutting out that tumor how far out he can cut that it wont affect other senses or abilities.
how can we tell the difference between one part of the brain that controls sight vs the part that controls smell just by looking at the brain? are there physical features that show us? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/5wdj1s/eli5how_we_accurately_accurately_map_segments_of/ | {
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"For starters, here's a map: _URL_0_\n\nThere are several large lobes of the brain, and the folds where they are, for the most part, fairly obvious. We also know what part of each lobe does what job, although the smaller areas of the lobes often do not have any exact border, they just kind of blend into their neighboring regions. Many functions we don't even know for sure where they are.\n\nyou'll note that vision and hearing are on different lobes entirely, they're not adjacent to each other at all.\n\nEvery brain is a bit different and they will never know exactly what will happen after cutting a part (or a part is destroyed by stroke, injury, infection, etc) but we have a rough idea of where most functions are located. Losing your occipital lobe would not affect hearing or or motor control but will destroy your vision, damage to the prefrontal area destroys ability to plan and act on intentions, but doesn't damage motor or sensory areas."
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9s9mrz | what are those hissing sounds made by large vehicles? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/9s9mrz/eli5_what_are_those_hissing_sounds_made_by_large/ | {
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"You may also be hearing a waste gate on a turbodiesel. Blowing off excess turbo pressure. Does it happen around shifts/during acceleration?",
"Heavy vehicles need to squeeze the brakes very hard, in order to stop. \n\nOn a typical car, when the brake pedal is pushed, a hydraulic mechanism uses brake fluid to transmit the force of your foot to the brakes, and also enhance the force, a little bit, by using power from the engine.\n\nOn trucks, this is not sufficient. So the truck uses engine power to pressurize an air compressor tank to high pressure, and when the brakes are pushed, this high pressure squeezes the brakes very effectively.\n\nWhen the brakes are released, the \"used\" air is released through a hose under the truck, making the hissing noise.",
"Two things; Brakes in trucks work differently than in cars. On big trucks the brakes are always applied, the engine drives an air compressor that uses compressed air to push the brakes off the wheels. When you push the brake pedal it lets the compressed air out of the system and applies the brakes. In the event of system failure the brakes are automatically applied and the vehicle stops. If the air leaks out it can simply be replenished. The vehicle won't move if the system is too damaged to function, unlike hydraulic brakes which will still allow the vehicle to move if the system is malfunctioning. Air brakes are safer than hydraulic brakes.\n\nIn addition to the brakes needing compressed air to release, the engine also uses compressed air. Combustion needs air and fuel. The more air you have, the more fuel you can use. The more fuel you use, the more power you generate. Trucks need to move a lot of weight and that takes a lot of power. The engine uses a different air compressor called a turbocharger. Turbochargers use exhaust gas to power a turbine that compresses air. When you decelerate suddenly the extra pressure in the system needs to be vented or it causes a back pressure surge which can damage the system. This air is typically recirculated, but can be vented to the atmosphere, by way of a blow off valve, causing a loud \"whoosh\" sound. This system can develop small leaks that are loud but are otherwise unnoticeable.\n\nIt's likely that the hissing sound you are asking about is the brake system leaking air. Trucks are allowed to leak a certain amount of air and the system will still be functional."
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9dv0ea | from where flies gets all of their energy to fly for a long periods of time without being tired? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/9dv0ea/eli5_from_where_flies_gets_all_of_their_energy_to/ | {
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"Flies and many insects are *EXTREMELY* efficient flyers. Also being tiny makes it a lot easier to lift your own weight into the air because of the way mass scales with size."
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3c3k82 | what is happening when strong mouthwash starts to hurt/burn in your mouth? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/3c3k82/eli5_what_is_happening_when_strong_mouthwash/ | {
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"Mouthwash generally contains alcohol, which causes the burning sensation you're feeling. It's perfectly normal. Mouthwash that contains alcohol (some do not) usually contain about 20-30%."
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2n08sd | why is it that when we remove "he/she" from a person it becomes "they"? | Why is it that when we remove the gender when referring to a single person, it then becomes plural? Example: "I was talking to a person and she said this." becomes "I was talking to a person and THEY said this."
Is the term "they" both plural and singular? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2n08sd/eli5_why_is_it_that_when_we_remove_heshe_from_a/ | {
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"The term 'they' is only plural, except for this special case you're talking about. There is no singular third-person pronoun in English that doesn't indicate a gender, other than 'it'. But 'it' has a connotation that implies something not human, either a lifeless object or a non-human organism. So 'they' seemed more natural to use as a genderless pronoun to refer to a person, even if it is traditionally plural.",
"Singular they (as this usage is called) is a workaround for crapness in the English language. Traditionally* there were third person pronouns that specify gender, \"she\" and \"he\", and one that specifies plural, \"they\". As gender isn't always known/relevant, \"they\" has been adopted to cover the singular case too. Since, \"they\" doesn't actually specify a number, it's the most correct pronoun in these situations.\n\nIt might also be worth noting that this is part of a larger drift away from singular/plural distinction in English. Compare \"thou\" and \"you\", one of which isn't used anymore.\n\n*It's not actually a new invention. If you google, you can find examples from Chaucer and Shakespeare.",
"Using \"they\" as a singular pronoun when you don't want to specify the gender is an old tradition in English, used by many authors including Shakespeare and Jane Austin.\n\nThere is no committee that gets to determine what is \"technically correct\". If enough of us use English a certain way, then it is correct. If great writers have been been using English that same way for centuries, then it is definitely correct.\n\nSo a person should use the singular \"they\" if they want to."
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3udsrr | do arches on bridges serve a significant purpose or are they only for appealing to the eye? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/3udsrr/eli5_do_arches_on_bridges_serve_a_significant/ | {
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"Arches are one of the most geometrically stable shapes, with the only geometric rivaling it being the triangle. It is for stability, ask any engineer.",
"Ancient Rome were the guys who really pioneered the design. The most famous example are the aqueducts. They first tried the flat wall design, but that became expensive and the walls were vulnerable to the windy climate that Italy has. So what they did is make the arch. It was cheaper as less materials were used, provided a very sturdy structure, and solved the wind problem as it would pass right through. The aesthetics were merely a very positive side effect."
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31apro | why is the first lady called the "first" lady? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/31apro/eli5why_is_the_first_lady_called_the_first_lady/ | {
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"There was no set title for the wife of the President, and was initially called a variety of things. One of those titles just made up for her was \"First Lady\" and it stuck around.",
"Back before time moved, before light existed, before life thrived, there was the first lady",
"Because the President is (has been so far, at least) the highest-ranking man in the U.S. So he is the 'first man'. His wife is therefore the highest-ranking lady, so 'first lady.'\n\nSimilarly, Vice President and 'second lady'. I suppose on that basis you could call the Speaker's wife the 'third lady' but it hasn't caught on.\n\nIn case a female president were ever elected, she would be the highest-ranking lady, and her husband would be the highest-ranking man, so would be the 'first gentleman'. (Although I don't believe a title has been set yet)\n\nThe real interesting event will be if a married LGBT president is elected. Assuming it's a woman, her wife couldn't really be 'first lady' because the president is already the highest-ranking female. I propose 'first consort'. "
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16q64k | i recently read that stuff doesn't burn in vacuums... what is a vacuum? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/16q64k/eli5_i_recently_read_that_stuff_doesnt_burn_in/ | {
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"A vacuum is where there is no air. Fire needs air (specifically oxygen in the air) in order to burn.",
"Something that has no air (or anything for that matter) in it. And because things need air to burn nothing burns in a vacuum. ",
"A Vacuum is the complete lack of anything in a specified Area. Space is a good example, there is no air, so no oxygen to fuel a fire...",
"Picture an empty room. In your head, that's probably a room with no people in it, no furniture, and white walls. However, there's one thing you probably didn't \"empty\" out of the room in your head - the air. Air is made of little particles, just like everything else. A vacuum is a space with absolutely nothing in it - no solids, no liquids, and no gasses.\n\n\"Air\" isn't just one gas - it's a mixture that's about 4/5ths nitrogen, 1/5 oxygen, and a small fraction of a bunch of other gasses. Fire is a chemical reaction that requires oxygen - so, in a vacuum, where there would be no oxygen gas, a fire won't last very long, if it can even start."
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2ve9al | what is actually going on when i pop my back? how does this compare/contrast to when i crack my knuckles? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2ve9al/eli5_what_is_actually_going_on_when_i_pop_my_back/ | {
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"It's pretty much the same thing. In between your joints is a gelatinous liquid type material called synovial fluid. During use throughout the day air bubbles build up in this fluid. And when you stretch the joints enough the air escapes making a pop sound! It releases pressure and that's why it feels so good. And it's actually not bad for you at all contrary to popular belief",
"More importantly, why do I instantly pop my back and knuckles as soon as I read the title?",
"More importantly: why does it feel so freaking good to pop your back?",
"Literally *dozens* of people just cracked their joints.",
"TIL people call cracking your back popping your back ",
"The noise is caused by a phenomenon called cavitation. When you separate the masses of cartilage and bone in your knuckles, it creates a vacuum between the masses, allowing dissolved gasses which have been built up in the fluids and meat of your joints to escape. The sound is the cavitations (tiny vacuum areas) collapsing by being filled back in with fluids and gasses.",
"I have a bunch of perineurial cysts along my neck and upper back. Whenever I hear the cracking and popping when I stretch or do yoga/Pilates, I get a jolt of irrational fear that I burst one of this cysts. Is the fear irrational, or could I actually be popping these things?",
"Now I don't know if it is cavitation, boiling or trapped air. Why do people sound so confident when giving an answer?? ",
"If you do a lot of yoga, you will be able to crack just about every joint in your body - your muscles surrounding your joints need to be flexible. Who needs a chiropractor? I can crack my spine all the way from the bottom to the top now. Cracking, for me, releases pressure on my joints. This relieves many pain issues, especially as you get older.",
"I have this weird thing that I can do if I put my arms out to my sides and pull them back. I can pop, whatever that area is about 6 inches above my sternum. Damn it feels good when I do it!",
"I think I may have [Spinal Instability](_URL_0_\n), since my lower back cracks almost every time I move. It hurts after a while.",
"I'm not sure what goes on technically, but it's like orgasming without using my penis ",
"Soooo.. all in all popping my knuckles and back doesn't fuck up my joints and cause arthritis like my parents told me??",
"Crack your knuckles not your back. I've had scoliosis and just recently had a micro discectomy on my L5 for a herniated disc at 26 (healthy, not overweight or a smoker). Your spine is precious, never pop it unless at a chiropractors office for adjustment. I promise you, you're causing more harm than good. Popping and twisting will torque your back in ways it is not meant to be. \n\nThe very best thing to do for back pain is 'press-ups' \n\nLeave your belt line on the floor relaxed while performing a push-up with your torso, this pushes the disks back into place and curves your spine in a natural motion. Do 10, hold for 2-3 seconds (feeling stretching in your core area (tummy) is good). Or just do one big long one and hold until it stops hurting. \n\nBack muscles do less for holding you up than your core, 6pack abs are better than a hills and valleys back sculpting for support. Live by these guidelines.",
"I've cracked my lower/middle back, knees, elbows, fingers, shoulders, ankles and neck. I have done this since I was young (the spine and fingers) and am now 46 and have no signs of any kind of joint pains. I lift a bit and think this contributes to healthy joints. I was told that when you crack a joint it releases synovial fluid which acts like a lubricant and might ease tightness, hence the relief felt? Im no Dr....just my guess. But I did want to share that after many years of knuckle cracking i have no issues...",
"Typically the pop you are talking about is a release of NITROGEN gas. Cavitations (gapping the joint/popping) can be therapeutic. While I would not recommended doing this yourself, I would see a Chiropractor/Chiropractic Physician. \nWhen you are \"popping\" your back you typically gapping the joints that don't need the \"pop\". This is because the joint your want to pop is hypomobile (decreased motion) and the joints around it become hypermobile which are easily moveable. A Chiropractor will find the areas needed, adjust them so the motion of the joints are normal. \nLeft untreated these areas of hypomobility (Verterbral Subluxation Complex) can lead to a mired of problems which includes chronic neck, back, extremity pain, and more. \nThere are other reason's you may hear pop's and cracks as well. \nHope that helps! ",
"And hey is it that I can pop certain nuckles, my big toe or instance, indefinitely? I can literally sit here and make it snap crackle pop all day.",
"I want to know what happens when I pop my chest bone. I sit scrunched for a bit then stand up and stretch my back and it feels like I'm getting stabbed in the chest.",
"Yeah mom. Your a nurse and you claim to know for sure that cracking my knuckles will cause autism. It its true, then why did you crack your knuckles enough to become stupid enough to believe such uneducated bullshit ",
"I don't know what happens inside, but I feel refreshed after I pop my back."
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7ewn89 | how were women forcibly sterilized in the us? | Couldn't they just refuse? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/7ewn89/eli5_how_were_women_forcibly_sterilized_in_the_us/ | {
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"They either weren't told and it was performed under the guise of another operation, they were coerced under threats of some sort of punitive action (for example threatening to revoke privileges for women in prison), or were performed against women who didn't have the resources to defend themselves e.g. mentally unstable women. ",
"Most forced sterilizations in the US were done at the order of eugenics boards, targeting those with disabilities or criminals. In many instances the victims were told they were simply doing some routine medical procedure and not informed that they were being sterilized.",
"The early 20th century saw the rise of eugenics in America, which was the theory that everyone would be better off if some people can't reproduce.\n\nIf someone has guardianship of you, they can have any medical procedure performed on you if he and the doctor think is medically necessary. Also a nimber of them were already institutionalized. So no. They couldn't object.",
"I can't speak for every case, but in many cases, women didn't even know it happened until years later. They would go in for a surgery and while they were under, a doctor would sterilize them.",
"This is an extremely loaded question. The eugenics programs of the United States were legally designed around keeping the disabled and other genetically unfit out of the breeding pool. It was labeled with pure intentions of humans having the ability to direct their own evolution. To build a stronger, smarter master race. It was endorsed by numerous colleges and financial organizations.\n\nBoth men and women were sterilized from sometime in the late 1800s to the later half of the 1900s. In many cases they were fooled into thinking that it was another procedure or in the case of criminals, forced sterilization. In North Carolina, if an individuals IQ tested less than 70, said person would be sterilized. Each state that led these programs used different high minded excuses for their actions.\n\nThere is irrefutable evidence that in many states they used their legal excuses to sterilize minority communities. Hitler and many prominent Nazi's used the United States as an example to create their own eugenics programs due to its large acceptance by the populace."
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5qz2v3 | why are people uninstalling uber after the protests? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/5qz2v3/eli5_why_are_people_uninstalling_uber_after_the/ | {
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"The New York Taxi Workers Alliance asked it's member to protest against Trump's immigration policy by not picking up passengers at JFK airport. Uber though was sending drivers there to capitalise on the lack of taxis. So some people in favour of the taxi protest are now refusing to use Uber as a form of protest against Uber.",
"First of all, the reason they're doing it right now is, as protests got underway at JFK airport the other day against Trump's executive order barring people from 7 predominantly Muslim countries from entry to the US, the New York taxi companies went on a one hour work stoppage, during which time they refused to go to JFK in order to contribute to the protests. That's huge, since taxis are a major way to get to JFK airport--most people don't own cars in New York (you can still get there by train and bus and subway). Seemingly in response to this, Uber turned off \"surge pricing\" for people going to JFK. In other words, Uber saw a big uptick in demand to go to JFK that evening because people couldn't go by taxi. When Uber experiences a surge in business, they raise their rates substantially. But they didn't raise them, they kept them the same for that evening, and therefore muted the effects of the taxi protests. In addition. Travis Kalanick, the CEO of Uber, is perceived as being somewhat close to Trump--Trump appointed him to a business council, the Strategic and Policy Forum. Most leaders in Silicon Valley have kept their distance from Trump. So taken together, Kalanick is seen as a supporter of Trump in some of Trump's hated policies. A memorable tweet against Uber was \"I don't need a ride to Vichy.\" Vichy was the seat of the French government that was a puppet of the Nazis during WWII, so invoking Vichy implies that Kalanick is a collaborator in racist Trump policies.\n\nIn response, Kalanick has done some backpedaling and says he'll talk to Trump about the ban.",
"Basically a large scale tantrum. People are pissed that Uber isn't joining in on the sheep herd of disrupting commuters from getting from point A to point B at JFK airport that taxi's have taken part in. *Obviously* this means Uber *must* support Trump's muslim ban (great logic), so they're urging people to delete Uber since they're assuming they approve of Trump's ban since they're doing their job. Yes... This is actually happening. I thought it was a nightmare too."
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7iocf6 | in the chess games between google's alphazero and stockfish 8, why is each game different? why isn't each game just the same every time | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/7iocf6/eli5_in_the_chess_games_between_googles_alphazero/ | {
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"In the evolution of AlphaZero's and other AIs brains, they add a little bit of randomness into it, analogous to how humans and other species have adapted over the years, because some random mutation might facilitate reproduction and survival much better, so that feature becomes more pronounced over time. In the same way, until the game is completely solved, they continually add a little bit of randomness so that for example the program doesn't get caught in the same trap over and over again, whats called a local minimum. ",
"Ahoy, matey! Yer not alone in askin', and kind strangers have explained:\n\n1. [ELI5: Why a chess computer doesn't respond the same way every time to the same attack pattern. ](_URL_1_) ^(_5 comments_)\n1. [ELI5: Why does a computer use different openings when playing chess? ](_URL_2_) ^(_7 comments_)\n1. [ELI5: If I let two chess engines play each other 100 times, how do they play 100 different games if there must be one optimal game? ](_URL_0_) ^(_10 comments_)\n"
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2kdygs | why do i read stories every few months about researchers developing amazing new battery technology but batteries still suck after so many years? | Thanks everyone for the interesting comments. I learned a lot.
Summary of the answers:
*Current batteries are based on lithium-ion technology which was developed a very long time ago so it is now very mature. Mature technologies won't change that much more or get that much cheaper.
*Li-Ion battery technology has actually improved considerably in the past two decades. Progress has slowed recently.
_URL_1_
*Modern smartphones and other consumer electronic devices also use a lot more power which cancels out the improvements in the battery.
*The trend in consumer electronics is towards smaller and thinner devices so the size of the battery must also be reduced. Smaller batteries hold less charge.
*New batteries based on more promising materials take a lot of time to go from the lab to a commercial product due to concerns about safety.
*Media often over states and hypes new battery developments.
_URL_0_
*Great answer from a battery chemist. _URL_2_ | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2kdygs/eli5_why_do_i_read_stories_every_few_months_about/ | {
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"It takes a while for new technologies to reach the public. Then it takes longer still for the prices to be affordable for the average person.",
"Even though a researcher may have developed a new battery it is not cost effective. That new battery may last an extra 4 hours but it costs twice as much compared to the old battery. Lets say an old battery lasts 6 hours, it would be more cost efficient to just buy two old batteries which would give me 12 hours while the new battery would cost the same it would only provide 10 hours. \n\nSince the new batteries havent become affordable yet, no corporation would implement it in their products. Also it isnt affordable for the consumers.\n\n\nThere is also the matter of safety, even though they have developed the battery they still have to do safety tests. A lot of these new battery technology are developed in labs, which are often in ideal settings, so researchers have to make these products able to handle the world. ",
"Price. You will see some of these new battery technologies in commercial uses in which it would make sense to spend extra money. I work in a data center and I have seen some new battery technologies implemented into battery backups systems for servers. Some shit is just so critical that it would ruin a company if it went down for even a couple minutes. It would make sense to spend a couple extra thousand dollars on a newer technology. On the other hand, it would make absolutely no sense to spend so much extra money on a phone battery just so you could Facebook for a couple extra hours. ",
"The other answers about cost are great answers and cover the vast majority of situations and industries. The battery industry is competitive. However the oil industy hasn't always been so. The father of the Koch brothers invented a better oil refining process & patented it. The oil companies decided they would wait for the patent to expire than pay to license it. As any good capitalist spurned by other unregulated capitalists, he took his invention to the Soviets (the story doesn't end here but is beyond the scope of this example). Globalism has only changed the scale on which cabals have to operate to be effective; the problem hasn't gone away. So there is a small chance the reason we aren't getting better batteries is because they are being quashed. It is unlikely.\n\nEdit: spelling (mobile)\n\nEdit 2: I stand corrected, not only is this likely it happens. While the battery industry may be competitive, there are outside companies who benefit from its stagnation. Like the fossil fuel industry. These companies buy up promising technologies (the patents) so that nobody can use them.\n\nEdit 3: And then they can say to their share holders and in commercials they are diversifying or investing in green technology.",
"They don't. Battery technology has improved by leaps and bounds along with computers. The thing is, modern phones use much more power than old electronics did. If you somehow powered a Samsung Note 4 with an old flip phone battery, it wouldn't last long at all. ",
"How old are you? I remember many generations of batteries much worse than those we take for grantes today.",
"In addition to what everyone else has said, battery technology has improved amazingly. They use this technology to make phones that are more powerful and thinner. They still only last a day, because people prefer phones that are more powerful and thinner, not last longer.\n\nModern cell phones are coming out with 3200mah batteries at 3.8v, or 12.2 watt-hours. Compare to two AA batteries, 2000mah at 3v, or 6 watt-hours. Can you imagine if your phone used 4 AA batteries every charge, and how big that would be to carry around?\n\nThere are RC helicopter batteries out now the size of a pack of cigarettes that can produce 300 amps of power. That's as much as a car battery that weighs 20 pounds.\n\nI have some battery modules out of a 2012 Nissan Leaf that are the size of a stack of printer paper, and it holds 500 watt-hours of energy. It's 7.6v, 60,000mah. That's crazy. And, it can be quck charged in something like a half hour. That's insane. I remember growing up we were using Ni-Cad AA batteries that were 1.2 volts, 500mah, and took all night to charge.",
"Manufacturability is one aspect that has not yet been mentioned. In order to claim a breakthrough, a researcher in a lab needs to accomplish a feat a couple of times. Almost never do they mention that, for those 10 or so working prototypes, there were 5000 abject failures that each cost as much.\n\nIf you want to manufacture something for a profit, the yield (number of finished goods as opposed to fails at the end) needs to be in the 90% range (for most industries). R & D prototype yields can be in the 0%-10% range.\n\nProcess engineering is a multifaceted field that attempts to bridge the gap from 0-10% to something more palatable from a financial perspective. But it never gets press, because they aren't \"doing something new\" despite requiring a supreme amount of technical achievement.\n\nI mean, the first 10nm transistors were demonstrated in 2004. IBM and Intel have been producing 22nm technology for only the last 3-ish years, with first 10nm nodes 5-7 years out. And they are the bleeding edge of process engineering.",
"Did you not own a laptop 5 years ago? Batteries are way better now and CPUs are way more energy efficient.",
"They don't suck bro. My phone has the computing power of the computer I used to play HL2, minus a GPU, and I use it all day as a camera, browser, phone, game device, storage, and a business ledger and don't have to plug it in til I get home.",
"Expenses. Marketability. real-world testing.\n\nResearchers undoubtedly hype up their findings a little during the press release (hopefully not their actual research paper) so they can get more funding for more research. A battery that lasts twice as long! yay! ^^^with ^^^1/10th ^^^the ^^^durability Or a battery that charges 10x as fast! ^^^only ^^^at ^^^room ^^^temperature\n\nall these breakthroughs are also separate technologies, and it might not be possible to combine them.\n\nalso, return on investment. The battery factory making current-tech batteries have already been paid for, and anything they produce is basically pure profit. Companies need to make a huge investment start making new batteries. Worse yet, they end up competing against themselves, and their new tech might never get off the ground.",
"Some great answers here, but let me put another reason out there: lots of journalists have no idea how to evaluate the claims made by the (English major running the PR department of the) battery company. The company has an interest in making sure that the article you read is as favorable to the company as possible, so that the company will be perceived as more profitable and the stock price will rise. The journalist writing the article may have no science or engineering training or experience at all. That means that the journalist can't do much except repeat the claims made by the battery manufacturer. Finally, the journalist's editor has an interest in writing the biggest, most exciting headline he reasonably can, because he thinks that will make you more likely to read the article.\n\nSo there are two people in this process (the editor and the manufacturer) who want to portray this as the biggest, most exciting advance in a decade, two people (the journalist and the editor) who may not have the qualifications to actually evaluate what the manufacturer says, and no one at all with an actual interest in writing an accurate and unbiased report on this battery. So the article you read is full of inflated claims.",
"Stop using so much power. That full HD screen with high color depth on your smart phone is using more energy in an hour than an old-fashioned flip phone would use in a month. You can clearly see the gain in laptop lifetime. Modern laptops with high-end batteries can run low-inensity programs like a browser for 8 hour without problems. Laptops from, say 2008, struggled to give you 3 hours of consecutive browser use.",
"I've read somewhere that it takes 30-40 years for a research product to come to market. For battery example, lithium ion batteries were proposed in the 1970s but it wasn't until the 2000s when it really took off.",
"Cost to manufacture.\n\nDurability.\n\nSafety.\n\nRecharge time.\n\nDischarge rate.\n\nCapacity.\n\nEfficiency.\n\nHeating/Expansion issues.\n\nWeight.\n\nAll these things need to be considered for a practical battery. Most innovations address just one or two issues.",
"My time to shine! There are a few reasons this is the case. I hold a Masters degree in battery science (well, it's really a Chemistry degree), and worked as a battery scientist for three years. I posted an explanation to a similar question in a different thread and I've posted it below. The only thing worth adding is that a lot of people are talking about cost. Cost has been made out to be a big issue in this thread, but it's actually even worse than that. I would routinely spend the equivalent of $20-$30 per sample when I was doing research, and that was for a tiny square capable of storing minute amounts of power. THEN it has to be proven that it can be scaled up into a functional product, and THEN engineered to be inexpensive.\n\nMy response from three months ago is below:\n\nBatteries don't \"do\" what most other electronic pieces can do. There aren't any transistors to shrink or moving parts to remove, so you generally can't develop smaller, slimmer batteries with technological improvements the way you can develop electronics. How useful a battery is to us is almost entirely based on how much energy it can store (how it stores it may also be important, but not for the purposes of any discussion we're likely to have here), and how much energy it can store is entirely based on the physics and chemistry of the materials used to make it. You can't change the laws of physics, so a battery built with a particular chemistry will always have a maximum amount of energy it's capable of storing per cubic centimeter (or by whatever method of measuring you prefer to use).\n\nScientists are pretty good at predicting what sorts of materials are needed to improve things. A scientist could sit down and say \"if I had a material that could [Insert Property Here], I could make this so much better\". Creating those materials, or processing them in a way that makes your vision a reality, is the hard part. Battery technology improves much more slowly than most other fields because you can't just refine and make a smaller version of one - you have to develop some new chemistry that allows you to store more energy. It's actually been more practical in recent years to work on developing technology that just consumes less electricity.\n\nThe first problem with developing something better than current battery technology is that right now we're moving energy around primarily with Lithium and Carbon, which are two of the lightest best-packed elements on the periodic table. We've effectively reached the limit of what traditional chemistry alone is capable of doing.\n\nThe second problem is that storing lots of energy in small spaces is inherently unsafe. It's no good to have chemistry that lets me store lots of energy tightly if it's liable to release that energy violently at the slightest jostle. I drop my phone occasionally, and I'd prefer that it didn't explode when I do. Chemistry happens differently at different temperatures, so it's also important if the chemical reaction releases the most juice between 0-40 degrees Celsius because otherwise it wouldn't be practical for us to walk around with.\n\nWhat all of this means is that someone has to go forward to create materials and structures that don't exist using methods that haven't been thought of in order to create a new electrochemical reaction that may or may not actually be safe and reasonable to use.\n\nThere's a lot of time and energy invested into every step, and so batteries progress very slowly. Batteries are also a fairly recent \"problem\". People may have wished for longer lasting batteries in devices over the last century, but only in the last decade has the total population had a battery in their pocket at all times. When something significantly, obviously and proven better comes along than our current options, you can count on it being adopted fairly fast.\n\nEDIT - clarity\n\nEDIT#2 - you guys ask a lot of great questions. I love when people get excited over batteries and will do my part to keep interest up. Unfortunately, I had a super busy day, so I haven't been able to respond to many of you. I'm trying to make sure I get to everyone who sent me a message, it just might take me a little time.",
"This has more to do with the news media than it does the technology. As a researcher I see science and technology misrepresented all the time in the news: Cures for cancer, sustainable energy for the world, etc...The majority of technologies demonstrated in laboratories never make it to market because there are 1001 things that also have to happen besides the proof-of-concept in a laboratory. If there is the slightest potential that the technology may change the world by (insert hot media topic here) they will report it like it does. Because that gets viewers.\n\nMy area of expertise is not batteries but more biochemical engineering where I ready the primary research articles and see the news articles. They rarely report the science properly. Nor do I actually hold the media to such a standard but I wouldn't trust anything they say related to the sciences. I would assume this happens across other fields, as with batteries.",
"This is also true for medical cures as well. The fact of the matter is that science is grossly misrepresented in popular media. Media tends to overstate scientific discoveries. \n\nThe truth is that scientific results are often very conservative. Yes they might be able to improve on certain efficiencies but they are often under very specific conditions. Real world conditions have a lot of factors that change things. \n\nPopular media ignores this and often makes the claim that a certain discovery will lead to things changing immediately. \n\nIn my experience technology is constantly improving but not necessarily due to scientific improvements. That is a part of it but improvements to how things are sold and produced also factor in. For example, Tesla is able to make cheaper batteries not just because of improved chemistry but also manufacturing and economies of scale. ",
"Researchers may have developed a new battery technology that's twice as efficient, but the chemistry inside requires being heated to 500˚F. This is great for stationary (building backup power) or large vehicles (trains, ships) but it'll never make it's way down to the individual consumer level.\n\nI worked for such a company that developed a new battery technology. It was much more efficient (they wouldn't tell us lowly people just how much more— trade secret) but it had a few of these interesting issues. It will eventually make our lives better (probably about a decade away from being usable in any form), but it's not going to help your smartphone battery last longer.\n\n",
"Sucky batteries = you have to buy more of them = corporations make more money.\n\nGood batteries = corporations would most likely have to alter their production somehow, which would be a cost, in addition to you buying less batteries = corporations make less money.\n\nWhen thinking about changes to technology (or society & the world in general), filter it through \"would someone make an immediate profit off of this change?\" first. If yes, then it's likely to happen, if no then fuck you and your improvements.",
"I'm curious why the phone companies keep making thinner and lighter phones. \nI would gladly have a phone that weighed 50 grams more if it could double my use time.",
"I have some RC batteries with nearly 200C discharge rate. That means on my 6000 mAh pack for my 1/10 short course truck I could discharge the pack at over 1000 amps and be within specs for the pack. It weighs less than a pound and ive used it to start my full size car just for fun. I could not buy these just a couple years ago. It depends on the matket. ",
"In most of these stories they say that they've developed this new technology in the lab and that a consumer model will be available in 5-10 years. Say a radical new battery technology that they just need to iron out a few problems, but these problems can stop the entire process but are played down in order to get the funding to try to develop them. \n\nIn general if someone says they'll have a consumer version in 5-10 years be very sceptical. ",
"If you had a battery that lasted a lifetime, battery companies would go out of business. You make a battery that lasts half a year, you get return business. ",
"Btw, Elon Musk did briefly mention this \"bullshit factor\" in allegedly battery breakthroughs in a [MIT talk a few days ago](_URL_0_): Many parameters are important for a batteries and real cells that actually work can't have some huge drawback.",
"Because batteries have actually gotten a lot better from where they were many years ago. Twenty years ago, we were still using NiCads, because lithium had a habit of exploding every so often. Those batteries had something called memory, that would severely degrade the life of the battery if you didn't discharge it fully every time. They also held much less energy.\n\n",
"Every single time some engineer designs a battery capable of lasting twice as long, some other engineer designs a device which uses twice as much battery life.",
"You heard about the guy who invented an engine that made gasoline obsolete right? Yea he didn't live long.\n\n\nOr they flew Malaysian airlines.",
"Because every researcher has patents to their new battery improvement and won't let all of the other researchers combine their newly found knowledge by letting them pay to use their new patented idea at a cheap enough price that would make it profitable to mass produce and sell these new said batteries. ",
"Smart phone batteries get plenty of complaints, but, they are amazing for their relatively small size when compared to what they're required to do. It's a computer in your pocket ffs! ",
"Often there the breakthroughs come with drawbacks for other aspects of the battery that make them impractical.",
"For the same reason you hear NASA announce that Voyager 1 has left the solar system every year.",
"I can't help wondering if this is at all similar to how male contraceptive research has been inhibited because pharmaceutical companies would lose revenues from the pill. Are we sure battery companies don't just like the current state of the market, and are afraid of the innovation that would drive them out of business? ",
"The first thing you hear about a new technology is the BEST thing you will hear about it. After that come all of the \"yeah, but\" issues. \n\nYeah it charges faster, but it doesn't work in subzero temperatures. It is more toxic. It cannot be produced in large quantities. It uses unobtainium. ",
"There's also the issue of the fact that since batteries are getting better, software and hardware developers are allowed to develop more power draining systems. So your battery may hold twice as much juice now than it did two years ago but the programs and processors use twice as much too.",
"I wish everyone would edit with a \"conclusion\" like you did. It saves a bunch of time and helps me determine if I want to read the responses for more detail. Good guy OP!",
"I don't think the top comment is correct. Its not (only) about cost effectiveness. If it was, there would be premium models that offered the more expensive tech. It really has many impacts. Battery tech has improved a lot in the past years, while tech has also increased. As battery capacity/vol increases, so does the power consumption of the housing device. New screen types, processors, sensors, etc all use different amount of power. We could not run our current phones on battery tech from 10 years ago whatsoever. ",
"There are Patent Squashers and Patent Extorters. Patent Squashers buy up the patents and then do every thing they can to prevent them being used, sometimes under the guise of protecting their existing products or industry. Commonly they prevent people using the patents with lawyers suing anyone who comes up with something even close to it, and never letting anyone lease the patent. They will even use the lawyers to keep anyone quiet from publicizing anything about it (cease and desist and whatnot). The Patent Extorters buy the patent and then will only let it out if someone either leases it, or buys it for some exorbitant fee. Thus the new technology never gets out into the world. Bummer, eh?",
"lolwut? Just about every year I find myself marvelling at the progress of battery technology. What are you talking about?",
"I dunno, I've seen quite an improvement over my lifetime.",
"personally, I'd rather my phone's battery was 3x as thick. Our battery technology isn't terrible, but the mass market wants slim devices.",
"Because we'll never get a battery that does not wear out, has next to no weight, recharges in seconds, uses almost no space, has infinite capacity, does not burst out in flames and costs nothing.",
"I'll just list ~~all~~ many of the different things you want in a battery, you usually get one of them by sacrificing something else:\n\nMade from cheap, easy to source, materials \ncheap, high volume, production \nindividual cells consistent with each other \ndoesn't fail unpredictably \nhigh energy/unit mass \nhigh energy/unit volume \nlasts for many charge/discharge cycles \ncharges quickly \ndischarges quickly \nlow resistance \ndoesn't decompose at high temperatures \nstill works at low temperatures \ndoesn't catch fire when damaged \nisn't damaged when undercharged/overcharged \ncan be stored in any charge state without degrading \nholds it's charge over long periods \ndoesn't contain toxic materials \nfails safely \neasy to recycle \nhigh thermal conductivity \nflexible \ndoesn't expand or shrink significantly with changes in charge or temperature \ndoesn't outgas \ndoesn't eat babies \netc.",
"Batteries aren't *sucking*, the better they get, the more leverage technologies hard materials get to leverage that battery power.\n\nThink of it on economic efficiency terms, if you can produce **X**, you are going to push **Y** to that limit. If X is 5, and last year it was 4, then you are going to push Y from 4 to 5.",
"As batteries get better, smaller ones can power hungrier electronics. Beyond a certain point (say, a full day of work on a laptop, a weekend on one charge for a phone), more flashy/performance features trump longer battery life. This is separate from all the real-life manufacturing issues.",
"I am not a scientist nor do I have any scientific background but as someone who works in finance I believe there could also be an underlying economic reason for 'underperforming' batteries.\n\nCompanies are constructed like a house of cards where every cost is planned out and structured to maximize efficiency, this includes wages and the amount of people employed. The larger the company, the more this is true since small imbalances over a grand scale can lead to massive costs. These companies base their structure off an assumed demand schedule and if there were some revolutionary technology that were to come out and double the efficiency, you would also be effectively halving the demand. Batteries have been getting better, but I would argue that they have a set plan on how they are going to increase their efficiency over time so they can better roll the new demand schedule into their business model to minimize costs and potential job loss. I believe a similar evolution occurred (and is still occurring) in the lightbulb industry as well.",
"3 reasons:\n\n- Cost efficiency. The batteries may be better, but cost a lot more to produce these new batteries than the ones in currently in use\n\n- Patents. These developments are done at considerable RnD costs to the companies that make them. So they don't want to just give them away. They need to make the money back from the development of the batteries.\n\n- Longevity and Testing. One of the big parts of Batteries is their longevity, There's no use having a 24-48 Hr battery that burns itself out after 2-3 months. They could also be faulty after prolonged use with long term charging and depletion. They need to be stress tested to make sure that \"users\" aren't put at risk during normal usage. ",
"I would just like to comment that batteries today do not \"still suck\". Batteries are awesome now! Thinking they suck makes me feel really old. \n\nI'm 35, and when I was a kid, RC cars would run on these very heavy lead acid batteries. But we thought they were awesome because there was no cord attached to the wall.\n\nThen they came out with rechargeable batteries, then nickel metal hydride batteries that were lighter and lasted longer. They were still heavy as shit.\n\nI'm sure there are a lot of other variants that I'm forgetting, but fast forward to today, and these Li'poly batteries that we have in cell phones? These things are the shit!\n\nMy phone has a 3200mah battery that will keep my phone working for a day and a half of normal use. It's as thin as a couple of credit cards stacked up, and weighs next to nothing.\n\nIf you took the phone in your pocket back to 1980 in a time machine, you'd have to pull a Wagon full of batteries around with you to keep it working as long.\n\n....and it seems like they are always getting better."
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7t3yxy | why do humans universally use the same tone to ask a question? are there exceptions? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/7t3yxy/eli5_why_do_humans_universally_use_the_same_tone/ | {
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"That depends on the language they speak. In some Asian languages, there is no increase in pitch to indicate the words you are speaking as a question.",
"They don't.\n\nYou may be thinking that the pitch of your voice rises at the end of a question, but that's not always true. It *is* true of, for example, the French language -- but not usually of the English language.\n\nPay special attention to the way people ask questions in English. If the word order is the same as it is for a normal declarative sentence (\"He said that?\") then yes, your voice will rise at the end. But if the structure of the sentence already makes it clear that it's a question (\"How much does this cost?\") then most native speakers will actually use a *falling* intonation.",
"They don't. People within a given language will, and related languages will often share tendencies but it is not a universal truth with humans that pitch goes up at the end to indicate a question. ",
"They don't.\n\nPicking up on the previously mentioned Asian languages, some of them use intonation to determine what a word means. In Thai for example, the word 'maa' can mean dog, horse or something like 'come here'. Theoretically (and I'm not an expert by any means) any word could have up to 5 different meanings, one per each intonation: high, middle, low, rising, falling.\n\nIn English on the other hand, questions are also formed via so called copula inversion. In other words part of the usual sentence structure is different from the regular subject, verb, object."
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1akvyo | selling song covers | There's lots of artists doing covers of popular songs and selling those on iTunes. Do they have to pay royalties to the original owner of the song or can they somehow skip that? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1akvyo/eli5_selling_song_covers/ | {
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"Yes they have to do this and have to give credit to the original artist. \n\nIf an artists uses even a part of a song (called a sample) they have to pay royalties and give credit. Notable example of this is \"Ice Ice Baby\" of Vanilla Ice, in which a part of \"Under Pressure\" from Queen/David Bowie is used. \n\nFrom the wiki:\n > The song's hook samples the bassline of the 1981 song \"Under Pressure\" by Queen and David Bowie, who did not receive credit or royalties for the sample. In a 1990 interview, Van Winkle said the two melodies were slightly different because he had added an additional note, an anacrusis (\"pickup\") between odd-numbered and subsequent even-numbered iterations of the Under Pressure sample. In later interviews, Van Winkle readily admitted he sampled the song and claimed his 1990 statement was a joke; others, however, suggested he had been serious. **Van Winkle later paid Queen and Bowie and as a result, all members of Queen and Bowie have since been given songwriting credit for the sample.**\n\n*Du du du dudududu*"
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3i0c0x | why does crickets chirp at night? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/3i0c0x/eli5_why_does_crickets_chirp_at_night/ | {
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"They try to hide from their most common predators by staying quiet during daytime. And then come out during the night to attract a mate when it's too dark for birds to hunt."
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1dhd6f | what is a work study (as it applies to fafsa)? how does it work? | I was hanging out with some friends last night and they had mentioned that financial aid award information had been posted. A few of them had qualified for a work study. When asked what a work study is, no one could really give me a good answer so I figured I would ask. | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1dhd6f/eli5_what_is_a_work_study_as_it_applies_to_fafsa/ | {
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"On a college campus, certain jobs are reserved for people who need the money to pay for college. Work study is just the \"I need the money to pay for college\" status.",
"Just to clarify / expand on what Amarkov said - you get paid directly, it's money in your pocket, but these jobs are reserved for students who qualify for them. In other words, the money doesn't go directly to the school.",
"There's a lot of shit jobs that need to be done on campus - things like monitoring computer labs and checking out library books. These jobs are often given to students.\n\nWork-study is when the school is given part of the wages for the position (somewhere between 1/2 and 3/4 - I forget) and they agree to pay the rest. It's a good way for the school to bulk up on services it provides without spending money. It gets college students work experience (although in most WS jobs, it's just time to sit around and do homework).",
"If the student is getting paid from the federal government, how is this not essentially a college getting workers for free?",
"mer, I wanted to get in on this earlier. I'm a financial aid advisor at a university. Federal Work Study is a federal financial aid program for student employment. The college determines the students who are eligible to have work study positions (if they want them). Most colleges will select students to be eligible for work study positions because they are of high financial need. The college I work for generally chooses students with financial need and who are from out of state (so it's an additional resource since tuition is so much higher). If awarded work study, the student can apply for work study-specified positions, it doesn't mean they automatically have a job...but it does give them an advantage over students not awarded work study eligibility because so many more available positions are for work study students only. It is otherwise a normal part-time job, most are on or around campus so the student can have a balance of work and academics. They receive a bi-weekly paycheck sent directly to them like any other wage position and can use their earnings to pay for personal expenses, books, living expenses, student charges, etc. Generally, people on campus like to hire work study students because a portion of the student's wages is covered by the federal government, so it saves the university money...in addition to the student getting work experience, research opportunities, resume-building, etc. In terms of applying to FAFSA (Free Application for Federal Financial Aid), you have to file a FAFSA with your college and indicate interest in work study if you want it (and you are otherwise eligible for it). "
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1qn959 | why do human couples hold hands? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1qn959/eli5_why_do_human_couples_hold_hands/ | {
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32gt9f | what makes certain wine unbelievably expensive? |
So like, why do some wines, made in recent years, sell for over $10,000 but wines made from vineyards just down the road, which experienced near identical weather conditions, sell for less than $50.
Is it entirely down to the manufacturing process, and if it is, how can the price gap be so wide? Or is it more down to the name a vineyard has.
If anyone actually has any experience working in a vineyard and can explain the process better than wikipedia, that'd be swell.
| explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/32gt9f/eli5what_makes_certain_wine_unbelievably_expensive/ | {
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"It's pretty much supply and demand. Maybe Winery A got a good writeup in Wine Spectator magazine or something and Winery B didn't. I'd seen perfectly good $10 wine go to $50 or more just because of this. Also, some wineries have built up a reputation and name recognition. Would you rather buy Dom Perignon, or Fr. Jaques' Special Champagne?",
"The price gap is supply and demand, for certain prestigious brands.\n\nSo first of all, wine comes from grapes; and grape quality is dependent on many factors. Weather of course, but also soil, water, light, heat, and grower skill/decisions. AND of course, the actual grape vine.\n\nOld vines produce less fruit - thus, smaller production, BUT generally more concentrated and intense. Younger vines produce more fruit, but you have to prune them - the amount of pruning affects the concentration and quality of the juice you get. If your options are 'n' cases of wine at $60/case (wholesale) or 'n/3' cases at $120, you're probably going to prune sparingly to get as much juice and wine as possible, without creating garbage. On the other hand, if you can make truly great wine and have a name for yourself, then the options are 'n/3' cases at $1000, or 'n' cases at $1000 - for a year or two, and then the price per case drops down to $100 because nobody trusts you anymore.\n\nThen you factor in the slope of your land and composition of the soil (acidity, water retention or runoff), the light, the use of pesticides, mulch, etc.. \n\nSo now you have some amount of good-quality grapes. How do you make wine? Do you make wine that's going to mature over 10-50 years, or wine that's going to be drinkable about the time it hits the market, late next year (like about 90% of the wine sold)? The former leads to more expensive wine, and is harder to sell - BUT if done well, can establish you over time as a top-notch winemaker. Or drive you into bankruptcy even sooner.\n\nSo this pretty much determines the pricing for most wines between $8 and $80. Above that, things get...complicated.\n\nIf you're in Bordeaux for instance, your vinyard is likely ranked by the government. Your wine has to meet certain standards of quality and composition, and much of it is historical. There are, for instance, only five first-growth houses, and only one of them was not defined as such in 1855. (Chateau Mouton-Rothschild, which got promoted in 1973). If you're one off those, or one of a limited few others who have a similar cachet, you can pretty much name your price. The thing is, most of their wine is sold on futures at auction, so basically it's \"as much as someone is willing to pay.\"",
"I work at a winery - it's basically all hype if the grapes are from the same place. Wine is a dirty filthy disgusting delicious beverage. Those nasty ass grapes come in, barely get rinsed off, for fun we play \"count the lizards\" and see how many make it to the fermenters -hint: a lot, the must gets pumped full of sulfites to kill the bacterias, then yeast to ferment it.",
"1. Rarity\n2. Effort to create\n3. Reputation\n\n\naaaaand Speculation\n\nRarity is generally pretty self explanatory and typically refers to older wines, but certain vines, wineries and styles are much less common and still affect recent vintages. This goes hand in hand with reputation and effort in some cases. Certain wineries or wine lines are much more carefully handled and have stricter requirements for growth, picking and pressing. Certain areas have much higher reputations, certain wineries (premier cru, for example) just cost more for brand name and are therefore in higher demand. \n\nBut ultimately, most of the wines you see at those prices (Burgundy and Bordeaux especially) are bought purely out of speculation that the price will increase. ",
"People use wine to signal their taste and wealth. It's pretty good for this because a) it comes in a wide variety of forms from a huge number of small producers (individual vineyards) and b) it is consumed in social settings and shared with others. Because wine is consumed at social occasions, the wine purchaser uses it to signal to others his or her social taste (ability to pick a trendy wine, or one that matches the meal, etc) and wealth (ability to spend a lot of money on a disposable item, and share that item with others). The extreme granularity of producers mean they can all specialize in certain niches. So you have a whole stack of wines each specializing in being _even more_ expensive and trendy than the next bottle, so each group of increasingly wealthy people will be able to show off that they are slightly more wealthy than the next lower group. This produces a wide range of wine prices\n",
"So what I've learned from this thread: the price of wine has nothing to do with taste or quality. I'll stick with Three Wishes then. ",
"I'm not sure about $10,000 wines, because that's way out of my price range. For wines in the $1-$50 range, though, a lot of it is bullshit. \n\nMy FIL worked at a well-known very large Napa winery in the 90s, so this is from a firsthand account. When he was on the bottling line, they would have a huge vat of wine, and as they were bottling, they would occasionally have to change the labels that go on the bottles. It was the same wine in the vat, but many different labels for different wineries were put on the bottles before the vat was empty. At the store, the labels were from wines that sold from $5 to $50, even though it was the exact same wine. The price mostly depended on the name and heritage of the winery on the label.\n\nA similar thing is done with whiskey. Since it takes years to make your own whiskey, many new/small producers contract out with a mega-whiskey producer in the midwest for the first few years so that they aren't suffering years of losses they can't afford. Each bottle has its own label/brand, but they are all the same whiskey. \n\nSide note - there are a lot of wine additives that are kind of gross, like isinglass (non-vegan) or terracotta clay. My FIL also dumped huge bags of terracotta clay into the red wine vats to make them redder. ",
"Consistency also comes into play. I saw a graph on reddit a while back about price of wine and consistency (sorry I don’t have a link to it). It showed that the expensive wine that were over $100 were extremely consistent while the cheep wines varied widely. This doesn’t necessarily mean you will like the wine but if you find expensive bottles that you like it will be nearly identical for the other bottles for that particular year. If you find a cheap wine you like the next bottle may be a bit different. I know this isn’t exactly answering the question but is a cool correlation between wine prices.",
"What's the difference between a $5000 dog and $100 \"adoption fee\" dog? One comes with papers to prove a certain pedigree that you can brag about and show off to your canine-geek clique at the dog park. \nAt the end of the day, they're both dogs. \n \n**TL;DR - Nothing. You can have excellent wine for $30/bottle and the only thing it lacks is the pretentious-snobbery of a $10,000 bottle.**\n\n",
"People. People put value on things according to supply and demand, cachet and prestige, in order to make themselves feel superior over other people. \nThe rich are so fucking rich and stupid and wasteful these days, that vinters could put out total plonk and charge an exobitant amount of money for it, and rich idiots will still pay for it just because it's the most expensive on the market. \nThat's the real reason, but vinters and professional sommeliers will invent all kinds of bullshit to make people think they're actually getting value for their money. They're not. Source: Grew up in Tuscany drinking the best wines in the world with people who are now world-renown oenologists, who themselves have total contempt for their own industry. They'd never admit this in private. "
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710jgz | why are ashy elbows and knees so hard to clean? | I understand that human elbows and knees are prone to becoming "ashy" because, being relatively exposed movable joints with numerous folds of skin, they act as natural traps for dirt, debris, and dead skin cells.
It seems that other body parts with excess folds of skin can suffer from this same problem, but then why do only elbows and knees seem so hard to clean? Why do they *stay* ashy even after repeated vigorous scrubbings? Why can I not just bend my elbow in the shower (thereby stretching out the folds in the skin) and then scrub away until the "ashiness" is gone?
Is there a complicated scientific explanation, or am I just missing something obvious? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/710jgz/eli5_why_are_ashy_elbows_and_knees_so_hard_to/ | {
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"Because the key isn't \"just\" scrubbing. It's first about exfoliating, so not just washing, but using a very rough texture (like a loofah) on warmed, wet skin, to scrub off those dead skin cells. If you're having a tough time, be patient. Do a little every day, not a lot over one shower. Could take a week. Second, it's about heavily moisturizing those ashy areas, right after towelling off, while the skin is still moist. Use something good quality to moisturize. Not cheap dollar store stuff. Moisturize right after towelling off, while ashy skin is still damp, then again throughout the day. If it's cool/cold outside, it's even more important to moisturize throughout the day, because cool/cold air is really drying to skin. And voila. The cure for any ashy skin. "
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12mgrg | quantum spin | Tried getting my head around the wiki article (_URL_0_) but no luck :/
Any physicists help? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/12mgrg/eli5_quantum_spin/ | {
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"Do be afraid to try /r/askscience ",
"Also, try wiki \"spintronics\" for a practical application of electron spin\n\nFrom what I understand (being a junior in undergrad chemistry), electrons (e-) have either an up spin or a down spin (magnetic moments concerned with spin direction), meaning that depending on the direction of the e- ball, the charge on the electron is focused either up or down leaving a sort of \"electron hole\" on the other side of the electron. Two electrons per orbital per energy level means that each filled level has a balance of opposing e- holes and opposing e-charge.\n\nELI5- Electrons are like an inflatable ball after being hit in the air. Electrons in an atom have directional charge depending on which direction they spin, and there are 2 of them spinning in different directions in every orbital of the atom. Quantum scientists are now studying how to use this spin to store data in binary code (0,1)",
"What kind of science background do you have? Do you have the prerequisites to read that article? \n\nAnyway... Spin is, plain an simple, a property of subatomic particles. Just like an electron has mass and charge, it also has spin. It may sound weird, but spin is no more exotic than charge or mass. It's just another property of particles.\n\nAny given electron (which is one example of a group of particles called Fermions) can exist as one of two spins: +1/2 and -1/2. An electron cannot have any other spin. Other particles (called bosons) can only have integer spins: 0, 1, 2, etc. Fermions and bosons behave very differently because of their spins. Fermions with the same spin (for example, two electrons with +1/2 spin each) don't like each other, and don't want to get too close. Bosons with the same spin don't mind each other. \n\nThat article is just a mathematical formalization of what I've stated above."
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3jxxdg | why is breastfeeding apparently so difficult? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/3jxxdg/eli5_why_is_breastfeeding_apparently_so_difficult/ | {
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" > And if real problems with milk supply are that rampant, how did newborns survive waay back in isolated tribes and such? \n\nLots of them didn't! Kids died back in the old days, like, a lot of kids. \nThere's a lot more asthmatic people around today than there were a century ago. That's not necessarily because asthma is more prevalent, but because often, if you were a kid with it, you'd die. You'd have an attack and you wouldn't have the meds and you'd die. \n\n > It makes no sense from an evolutionary perspective to have a newborn child struggle to eat; that should be one of the simpler things in life. Are mothers just too hung up on a \"perfect\" latch and give up? \n\nSome babies (*especially* premature babies) don't have the suckle instinct. You can hold them up to a boob and they just plain won't *do* anything because they haven't developed. The mother can either pump herself, or get formula. And pumping ain't pleasant. \nSecond-hand info: Apparently there's a lot of pressure on mothers from midwives/medical literature to 'try suckling anyway' in the hope that they'll eventually catch on, because the immune system benefits are so huge. A few midwives I know suggest that's incredibly unfair and demoralising to parents of premature babies. \n\nSo, short version: Not every baby knows how to drink milk.",
"Ok here is my rundown. Breastfeeding is difficult for the following reasons:\n1) Supply and demand - Sometimes you just don't make enough milk, yet your baby is screaming for it constantly. My third night with my son, I spent 13 hours straight trying to feed him and he was not satisfied, eventually had to ask a nurse to give some formula so that I could rest.\n\n2) IT HURTS - Unless you are an expert at latching, you can get blindsided and end up with cracked and bleeding nipples. Mine were so sore and painful that I would cry a little when it was time to feed. \n\n3) Mastitis - This is the most sick I have ever been and I got it because baby slept longer than usual, I missed a feed, got lumps in the milk and before I knew it I was so sick I almost had to go to hospital.\n\n4) Amount - You never quite know how much milk your baby is getting, so its hard to tell if they have had too much or not enough.\n\n5) Post Partum issues - I had a really difficult birth, so I was in a lot pain for about 8 weeks, it hurt to stand and it hurt to sit, bfing was so difficult because of this.\n\nI persevered through all of this for 5 months, once I made it past the bleeding nipples and high demand, things got better and easier and I actually loved it, I did it for 5 months until I had to go back to work.\n\nEveryone else seems to have answered your other questions, but as a mother, that is why breastfeeding was hard for me.\nOther people have answered ",
"I'm a mother who has breastfed, and with issues too, so I can try and answer some of this. (It came as quite the surprise to me that it's not always just hold the baby to a boob and *voila!* instant latch.) \n\nYou ask why it's difficult to breastfeed. It's not always difficult, but there is a bit of a learning curve when you're new at it. How a baby latches is actually hugely important. Done right, there's minimal if any pain to it, milk flow is maximized, and the experience can be great. A bad latch, however, can mean cracked and bleeding nipples, blisters, and improper draining can lead to mastitis (I've had this, and it sucks.) There are other challenges to feeding, supply issues, even over supply, and tongue ties. My son had a severe front tongue tie that he had to have cut so he could drink anything at all and I had under supply that we had to deal with as well. Getting support from an LC meant I was able to feed him myself without turning to formula. Not that there is any shame at all in that, but we had other issues which made breastmilk more favorable (allergies). Other caviats to feeding can be the wrong position (babies have minds of their owns and they're stubborn little guys/girls sometimes), not recognizing hunger cues, no hunger cues, preferring to not feed under a cover-the list goes on! \n\nGetting to some of your other questions-most mothers don't give up on breastfeeding because they can't achieve a perfect latch. Some had issues I mentioned before with supply or tongue ties, but for others it's the pain (which is the worst for the first few weeks of feeding, even with a good latch. You do have to toughen up a little). For others it's lifestyle. Going back to work means less breastfeeding, less feedings means decreased supply. Turning to formula or strictly pumping may just work out better for them. There is a bit of taboo for some too. That is slowly changing, but it is still there.\n\nAs for why it seems other societies or even people in the past seemed to have little difficulty, that isn't really true. The creation of formula changed the survivability for infants of mothers that couldn't otherwise feed (not to mention our culture of feeding too). Surgeries for infants with severe tongue ties like my son or infants with other deformations like cleft lips have brought that survival rate up too.\n\nIn regards to your comment about other mothers stepping up to fill the gap by a mother unable to breastfeed, it was/is a thing! While you don't hear the term wet nurse all that often anymore, it does exist. It's not as popular a thing as it used to be due to modern societies' aversion to sharing milk, but you can still find it in its most popular form as milk banks nowadays. Women can donate pumped milk, they treat it, and then they dispense it to either NICU babies or mothers in need with babies that have allergies. Once my supply issues got better, I actually did this with the extra I had pumped too.\n\nHope this helps! ",
"I started to read some of the explanations. Good technical reasons. \n\nI am now a grandma. I breast fed my four children, my three daughters breast fed all of my grandchildren. My mother could tell the same story. My sisters successfully breastfed. We are a family who breastfed. \n\nThat is the answer, a woman who is surrounded by other women who are successful with breastfeeding will succeed. It is a culture thing. It is not hereditary. Yes there were problems, but if you are surrounded by other mums who know the ways past and through these problems, well, they get dealt with. Some of the massive problems, don't then arise. Experienced women know about proper attachment. One look - \"bubs looks like he/she is not latching on? maybe do this? or this?\" fixed. Bubs looks hungry? \"well lets let him have another feed or two\" - fixed.\n\nI was a breastfeeding counselor for a volunteer organization. for a number of years. This was at a time where breast feeding was not common in Australia. So back then I learned the correct technical advice, but it would have all translated comfortably to Grandma - or Sister to mum suggestions - often before it got to be a big problem.\n\nPerhaps I have simplified it. But many (not all) of the problems that are dealt with, should be simple management problems, not medical life/death problems. \n\nHaving had a quick read again at some of the problems the mothers here have had, maybe I could be seen as a hard indifferent b****, however some of those problems should not have happened with proper care. I feel sad that some mothers have had to go through that. ",
"I agree why did mother nature, for want of a better expression, make something that should be easy so difficult. But it is and it must be remembered that many kids died of malnutrition and starvation in the past so thank Goodness for formula if it is needed. "
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3pdo90 | after waking up from a nights sleep, why does it take so long to focus when you first open your eyes in the morning? | I get that maybe your pupils are very dilated from your eyes being closed all night. Why would it take any longer than any other extended period of time of say being in a dark area, or just closing them manually for a while. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/3pdo90/eli5_after_waking_up_from_a_nights_sleep_why_does/ | {
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286qds | why are actors/models paid significantly more than doctors/surgeons or medical professionals? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/286qds/eli5why_are_actorsmodels_paid_significantly_more/ | {
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"Actors and models usually make almost nothing. FAMOUS actors and models are paid a lot, but wast majority support themselves doing something else. \n\nWhy are famous actors and models paid more than surgeons? Supply and demand. There are many surgeons and they are close substitute for each other. There is only one George Clooney and for his fans, Brad Pit is not a substitute. Further more, surgeon may operate on one or two people a week, while George Clooney entertains hundreds of millions of people at the same time. ",
"Yes, it's to do with substitutability. If you want George Clooney for your movie, there's only one George Clooney, and if you think he'll make $50 million difference on the gross then you'll pay him $10 million. Doctors aren't unique, although their skills command a good salary, so they don't have that kind of pulling power. Millions of people look at Clooney or Nicole Kidman, think (rightly) that they're just as talented and end up waiting on tables into their forties as a result. These guys are never interviewed though, so you never hear about them, just the tiny handful that - pretty much at random - succeed."
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2125fv | americans for prosperity and the koch brothers | Recently on Reddit I've seen a lot of posts & comments regarding the Koch brothers in some way shape or form. Also my teacher was telling me how she didn't like the way the curriculum was going and that part of it had to do with the Koch brothers and Americans for Prosperity. In class every teacher has to write a "class objective" and "end results" with some days having exit tickets like punching out from work. Apparently this is is supposed to be to prepare us for a business setting? Everybody calls them literally hitler, so can somebody please explain to me what Americans for Prosperity is, why the Koch brothers are hitler, and why this is affecting the education system? Sorry if I sound ignorant, I am just uninformed and would like to know. | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2125fv/eli5_americans_for_prosperity_and_the_koch/ | {
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"I want to tell you that you are in no way ignorant, and I must remind you that simply asking questions confirms that. I am just as misinformed as you are uninformed, and want to say you are asking questions that must be asked. I will be watching this thread as carefully as you will be.",
"Without knowing much about where you school is, what state you're in (assuming you're from the U.S.), and whether you're in a private, public, or charter school, I can't say for sure what impact the Koch Brothers are having on your education system.\n\nWhat I can tell you is that there has been a big push in what's called the \"education reform movement\" in the last 10 years or so. The purpose of the reforms is to try to incentivize more effective teaching strategies so that American students can perform better. There are a lot of different approaches that people have proposed and/or implemented (including standardized testing, the Common Core curriculum, private school voucher lotteries, the Race to the Top program, and replacing low-performing public schools with charters) and there's a lot of money going into research and experimentation into these approaches.\n\nA lot of the research is coming from public and private higher educational institutions, but there's also a lot of research being commissioned and funded by various philanthropists and political advocates, especially among the very wealthy. The Koch Brothers are two very wealthy men who have made millions (or billions?) from the energy industry, and they have become notorious in recent years for the large amount of spending they put into political advocacy, especially in support of conservative politicians, and conservative causes like the privatization of traditionally public functions. They do this through a number of different organizations that they have created (for tax and other legal purposes) the most prominent of which is called Americans for Prosperity.\n\nI don't know exactly what Americans for Prosperity has to do with school reform, but it sounds like your teachers are pinning the blame for whatever new requirements they are dealing with (objectives, end results, exit tickets) onto the advocacy efforts of the Koch Brothers. They may well be right, but it's probably an oversimplification of the issue. Without knowing the specifics, it would appear that your teachers are opponents of Common Core. Common Core is very popular among conservative and liberal advocacy groups, politicians, and philanthropists, but it's much less popular among teachers."
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ln81c | ceramic vs. steel (or metal in general) | I'm a cook, and at work we use ceramic honers and I have no clue why.
Do tell. | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/ln81c/eli5_ceramic_vs_steel_or_metal_in_general/ | {
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"OK, materials scientist here and I'll try to explain it simply...\n\nI'm not sure how familiar you are with the periodic table, but going across from right to left, there are more electrons added to the outer most shell (called valence electrons) all atoms want to have eight electrons in this shell. So in order to be happy, they tend to give up, or take electrons.\n\n Metals are the elements in the middle of the periodic table. Their electrons are kinda happy the way they are so they don't really need another element to make them happy. They tend to be 'pure' and not form compounds (although they can, but its not a compound in the traditional sense). In a piece of metal, the individual atoms are all basically bonded to each other and they share electrons (they call the shared electrons the \"sea of electrons\". Seriously). Electrons conduct electricity by freely moving around the material and kind of jumping between atoms.\n\n Now, ceramics are compounds of more then one type of element. These atoms usually form pairs of one atom that wants more electrons and another that wants to get rid of electrons (it can be more in order to make everything neutral). These two elements are basically \"locked\" together because they only share the electrons between themselves. In ceramics there isn't electron moving around like there is in a metal, so the electricity doesn't flow as freely.\n\nThis was more of a classical explanation for the differences, I could go into quantum mechanics... but that's a little too advanced for ELI5",
"I don't know anything about cooking or honers, but I can offer a materials science perspective.\n\nMetal is a ductile material, basically meaning that is bends before it breaks. Ceramic is a brittle material, meaning it breaks without deforming. This means that the honer will stay \"sharper\" for longer, because when the ceramic it is made of is rubbed against the knife, it will break off and leave sharp edges instead of just being worn down, like a metal one would. \n\nLike I said, this makes sense from a materials science view, but there may be other reasons that I am not aware of. ",
"OK, materials scientist here and I'll try to explain it simply...\n\nI'm not sure how familiar you are with the periodic table, but going across from right to left, there are more electrons added to the outer most shell (called valence electrons) all atoms want to have eight electrons in this shell. So in order to be happy, they tend to give up, or take electrons.\n\n Metals are the elements in the middle of the periodic table. Their electrons are kinda happy the way they are so they don't really need another element to make them happy. They tend to be 'pure' and not form compounds (although they can, but its not a compound in the traditional sense). In a piece of metal, the individual atoms are all basically bonded to each other and they share electrons (they call the shared electrons the \"sea of electrons\". Seriously). Electrons conduct electricity by freely moving around the material and kind of jumping between atoms.\n\n Now, ceramics are compounds of more then one type of element. These atoms usually form pairs of one atom that wants more electrons and another that wants to get rid of electrons (it can be more in order to make everything neutral). These two elements are basically \"locked\" together because they only share the electrons between themselves. In ceramics there isn't electron moving around like there is in a metal, so the electricity doesn't flow as freely.\n\nThis was more of a classical explanation for the differences, I could go into quantum mechanics... but that's a little too advanced for ELI5",
"I don't know anything about cooking or honers, but I can offer a materials science perspective.\n\nMetal is a ductile material, basically meaning that is bends before it breaks. Ceramic is a brittle material, meaning it breaks without deforming. This means that the honer will stay \"sharper\" for longer, because when the ceramic it is made of is rubbed against the knife, it will break off and leave sharp edges instead of just being worn down, like a metal one would. \n\nLike I said, this makes sense from a materials science view, but there may be other reasons that I am not aware of. "
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nkfcg | bayesian probability | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/nkfcg/eli5_bayesian_probability/ | {
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"In mathematics, a probability is a number between 0 and 1 that is assigned to an event. We understand intuitively that this number is related to the 'likelihood' of that event—if the weatherperson says that there is an 80% (remember, 80% = 80/100 = .80) chance of rain tomorrow, we feel that it will probably rain, but if they say there is only a 10% chance, we feel it probably will not. However, describing mathematically exactly what that number means is complicated. One very simple way is as a frequency—for example, to find the probability of rain tomorrow, we might calculate the number of days out of the last 100 that it has rained. This method works fairly well for random physical processes, like flipping a coin, or rolling a die, but it would be a pretty bad strategy for the weather channel, because the weather isn't totally random. We know that in the long term only a certain proportion of days are rainy, but that doesn't much help us guess whether it will rain tomorrow in particular, and that's the information we want. This is where Bayesian probability comes in.\n\nIn the Bayesian interpretation, a probability isn't a frequency, or even necessarily something we've measured. It's an abstract value that we assign to a hypothesis (in our case, the hypothesis \"it will rain tomorrow\"). Using probabilities to mean abstract values rather than physical observations can be convenient in mathematics because it lets us extend logic—the study of valid inference and reasoning, which is traditionally about statements that are either true or false—to reason even when we don't know whether our statements are true or false. Intuitively, we can think of the probability as our \"degree of belief\" in the truth of the hypothesis in question: the higher it is, the more we all want to set out our boots for tomorrow; the lower it is, the more we're all thinking about selling our umbrellas. Of course, assigning a value to that probability arbitrarily would hardly do us any good. The important part of Bayesian probability is the way we adjust that value based on evidence we acquire about the situation. Evidence is a statement we take to be true—in science, usually because we have observed it in reality—and then use to reason about the truth of our hypothesis. Our initial value is our \"prior probability\", or just \"prior\"; we then use evidence to arrive at a new value for the probability, our \"posterior\", which (assuming we're reasoning about reality!) we hope is closer to the truth. This posterior can then be taken as a new prior, and our probabilities adjusted over and over, to achieve an ever more accurate picture of reality.\n\nAlthough our priors might be subjective (I might make a different guess about the likelihood of rain tomorrow than you would, even if I didn't have any particular evidence to point to, because people are funny), the process Bayesian reasoning uses to arrive at the posteriors is objective, and doesn't vary from person to person. If I say it's 30% likely to rain tomorrow, and you say it's 40% likely, but we both observe that it's more likely to rain on cloudy days, then when we look outside tomorrow morning and see that it's cloudy, we'll both revise our estimates upwards. What's more, if we know just how much more likely it is to rain on cloudy days than non-cloudy days, we'll know exactly how much to revise our estimates—which also means that not only can I say how likely I think it is given our new evidence, but I can also say how likely you now think it is, and vice versa. Bayesian reasoning is quantitative, not just qualitative (and can therefore distinguish between strong and weak evidence: strong evidence forces us to make large adjustments, while weak evidence has a smaller effect). The exact method of adjusting probabilities is a very simple (if not always intuitive) calculation called Bayes' Rule, of which you can find a detailed and extremely gentle explanation [here](_URL_0_). (I do not give the equation itself, as the author of that article holds it back until the end for the sake of pedagogy, which I find reasonable enough.)\n\n(This is my first LI5 explanation; feel free to ask questions if I've been overcomplicated or unclear!)",
"I'll give you an example, then we can generalize.\n\nLet's say that 10% of the population has a disease.\n\nLet's say that I determine a test for this disease, some kind of blood chemistry analysis kinda thing that your doctor can do in the lab. Let's say that the test is correct 90% of the time. In other words: When 100 people who do not have the disease all take the test, ten of them will get a false positive result. And when 100 people who DO have the disease all take the test, ten of them will get a false negative result.\n\nYou take the test. You get a positive result.\n\nWhat are the odds that you have the disease? 90%. No.\n\n50%.\n\nWhy?\n\nBecause if the whole population takes the test, 10% of the population will have the disease, so 90% of THEM (i.e. **9% of the whole population) will get a true positive result** (and 1% of the population will get a false negative)... and 90% of the population will not have the disease, so 90% of THEM will get a true negative (and the other 10% of them, i.e. **9% of the whole population, will get a false positive**).\n\nIn short, there are as many false positives as there are true positives. So if you get a positive result on the test, the chance is 50-50 that you actually have the disease.\n\nLet's look at a population and understand the numbers of people involved (so it's a little more real than just multiplying percentages): In a town of 10,000 people, one thousand will have the disease (900 will get positive tests results, and 100 will get incorrectly negative test results) and nine thousand will not (8100 will get negative test results, and 900 will get incorrectly positive results).\n\nSee? 900 accurate positives, and 900 false positives. If you get a positive, the chance is 50-50 that you have the disease.\n\nThis 50-50 thing is true in this example because I said that 10% of the population has the disease, and 10% of the tests come out wrong. That's why the number of false positives matches the number of true positives.\n\nReal life is rarely like that. So let's change the numbers. Say that now, 30% of the population has the disease. And say the test is still the same, 90% accurate.\n\nWith these new numbers: Of the 10,000 people in the town, seven thousand do not have the disease (6300 will get a negative test result and 700 will get a false positive) and three thousand do have the disease (2700 will get a positive test result and 300 will get a false negative). This means that, if you get a positive, you're one of 3400 people who got a positive, i.e. 2700 real ones plus 700 false ones. So if you got a positive, there's about an 79% chance (2700 out of 2700+700) that you actually have the disease.\n\nThe lesson? If you sample some data, sometimes you can only interpret what that data tells you in light of some other things you know about this kind of data. ([If you get an email with certain words, you can only determine the probability of that email being spam if you know the likelihood that emails with those words are spam](_URL_1_)).\n\nQuantitatively:\n\nLet's look again that that town of 10,000 people.\n\n * Probability of having the disease = 30% (call that **P of A**).\n\n * Probability that the test comes out positive = 34% (call that **P of B**... that's 27% chance of you having the disease AND the test being correctly positive (30% times 90%) and a 7% chance of you not having the disease AND the test being incorrectly negative (70% times 10%)).\n\n * Probability that the test is positive given that you have the disease = 90% (call that **P of B given A**).\n\n * So the question is... what is the probability that you have the disease given that the test came out positive? (call that **P of A given B**).\n\nBayes' theorem says;\n\nP of A given B = P of B given A, times P of A, divided by P of B\n\nIn this case, it's 90% times 30% divided by 34% = 0.90 x 0.30 / 0.34 = 0.7941, i.e 79%.\n\nThis kind of math can be used to quantitatively describe situations where we know that A happened, and we know that A tends to happen when B happens (or will happen), so how likely is it that B happened (or will happen)? If all our data is indirect and probabilistic, the more data we have then the more certain we can be that the truth is what the data indicates (rather than all the data happening to indicate the wrong thing).\n\nI'll link to more information so you can see what I mean: Here's [an interesting real-world example](_URL_2_) and here are [a couple more easy mathematical examples](_URL_0_).\n\nEDIT: Clarity, formatting",
"Frequentists say that probabilities correspond to ratios of actual events. So, you could say that there's a 20% chance of drawing a red ball at random from an urn that has red and green balls in it. You could even say the urn is 20% likely to give a red ball. \n\nBayesians believe that probability corresponds to uncertainty in a mind due to partial information. They would say things like \"I believe that if I draw a ball from this urn, there is a 20% chance it will be red.\" That's pretty similar to what the frequentist would say, but the Bayesian is making it clear that it is his *belief* about the urn, not an property of the urn. After all, if someone with x-ray vision looked at the urn and saw that the ball on top was red, they would say there was a 100% chance of getting a red ball. \n\nThis also means the Bayesian can say things like \"I'm 99% confident the sky is blue right now.\" A true frequentist would gasp in horror at this, because there's no way to view that probability as corresponding to a ratio of frequencies of events in the world. The Bayesian instead simply means that when he says he's 99% confident in something, he expects that 1 out of every 100 times he makes a statement like that, he'll be wrong. \n\nBecause Bayesians view probabilities as estimates of belief, they can do things like ask \"I used to think something was 50% likely, but I now have evidence that it is more than 50% likely. What should my new estimate of the probability be?\" It turns out there is a mathematical rule that tells you *precisely* how much to change your probability estimate, based on how likely the evidence is. It's called Bayes Rule. \n\nFor example, if I think cancer is rare in the population, and I came up positive on a cancer screening test, I can calculate my new estimate of how likely it is that I have cancer. Before I thought it was very unlikely; now it is somewhat more likely, because the cancer screening test comes up positive more often when you actually have cancer; and Bayes Rule tells me exactly how much to change the probability. \n\nTLDR: Bayesian probability is a measure of belief or uncertainty in a mind due to partial information.\n\nNote: Credit to ET Jaynes's book *Probability Theory: The Logic of Science* and E. Yudkowsky's [blog post archive](_URL_0_).\n\nYou might also like these:\n[An Intuitive Explanation of Bayes' Theorem](_URL_1_)\n\n[A breakdown of the previous](_URL_2_)",
"In mathematics, a probability is a number between 0 and 1 that is assigned to an event. We understand intuitively that this number is related to the 'likelihood' of that event—if the weatherperson says that there is an 80% (remember, 80% = 80/100 = .80) chance of rain tomorrow, we feel that it will probably rain, but if they say there is only a 10% chance, we feel it probably will not. However, describing mathematically exactly what that number means is complicated. One very simple way is as a frequency—for example, to find the probability of rain tomorrow, we might calculate the number of days out of the last 100 that it has rained. This method works fairly well for random physical processes, like flipping a coin, or rolling a die, but it would be a pretty bad strategy for the weather channel, because the weather isn't totally random. We know that in the long term only a certain proportion of days are rainy, but that doesn't much help us guess whether it will rain tomorrow in particular, and that's the information we want. This is where Bayesian probability comes in.\n\nIn the Bayesian interpretation, a probability isn't a frequency, or even necessarily something we've measured. It's an abstract value that we assign to a hypothesis (in our case, the hypothesis \"it will rain tomorrow\"). Using probabilities to mean abstract values rather than physical observations can be convenient in mathematics because it lets us extend logic—the study of valid inference and reasoning, which is traditionally about statements that are either true or false—to reason even when we don't know whether our statements are true or false. Intuitively, we can think of the probability as our \"degree of belief\" in the truth of the hypothesis in question: the higher it is, the more we all want to set out our boots for tomorrow; the lower it is, the more we're all thinking about selling our umbrellas. Of course, assigning a value to that probability arbitrarily would hardly do us any good. The important part of Bayesian probability is the way we adjust that value based on evidence we acquire about the situation. Evidence is a statement we take to be true—in science, usually because we have observed it in reality—and then use to reason about the truth of our hypothesis. Our initial value is our \"prior probability\", or just \"prior\"; we then use evidence to arrive at a new value for the probability, our \"posterior\", which (assuming we're reasoning about reality!) we hope is closer to the truth. This posterior can then be taken as a new prior, and our probabilities adjusted over and over, to achieve an ever more accurate picture of reality.\n\nAlthough our priors might be subjective (I might make a different guess about the likelihood of rain tomorrow than you would, even if I didn't have any particular evidence to point to, because people are funny), the process Bayesian reasoning uses to arrive at the posteriors is objective, and doesn't vary from person to person. If I say it's 30% likely to rain tomorrow, and you say it's 40% likely, but we both observe that it's more likely to rain on cloudy days, then when we look outside tomorrow morning and see that it's cloudy, we'll both revise our estimates upwards. What's more, if we know just how much more likely it is to rain on cloudy days than non-cloudy days, we'll know exactly how much to revise our estimates—which also means that not only can I say how likely I think it is given our new evidence, but I can also say how likely you now think it is, and vice versa. Bayesian reasoning is quantitative, not just qualitative (and can therefore distinguish between strong and weak evidence: strong evidence forces us to make large adjustments, while weak evidence has a smaller effect). The exact method of adjusting probabilities is a very simple (if not always intuitive) calculation called Bayes' Rule, of which you can find a detailed and extremely gentle explanation [here](_URL_0_). (I do not give the equation itself, as the author of that article holds it back until the end for the sake of pedagogy, which I find reasonable enough.)\n\n(This is my first LI5 explanation; feel free to ask questions if I've been overcomplicated or unclear!)",
"I'll give you an example, then we can generalize.\n\nLet's say that 10% of the population has a disease.\n\nLet's say that I determine a test for this disease, some kind of blood chemistry analysis kinda thing that your doctor can do in the lab. Let's say that the test is correct 90% of the time. In other words: When 100 people who do not have the disease all take the test, ten of them will get a false positive result. And when 100 people who DO have the disease all take the test, ten of them will get a false negative result.\n\nYou take the test. You get a positive result.\n\nWhat are the odds that you have the disease? 90%. No.\n\n50%.\n\nWhy?\n\nBecause if the whole population takes the test, 10% of the population will have the disease, so 90% of THEM (i.e. **9% of the whole population) will get a true positive result** (and 1% of the population will get a false negative)... and 90% of the population will not have the disease, so 90% of THEM will get a true negative (and the other 10% of them, i.e. **9% of the whole population, will get a false positive**).\n\nIn short, there are as many false positives as there are true positives. So if you get a positive result on the test, the chance is 50-50 that you actually have the disease.\n\nLet's look at a population and understand the numbers of people involved (so it's a little more real than just multiplying percentages): In a town of 10,000 people, one thousand will have the disease (900 will get positive tests results, and 100 will get incorrectly negative test results) and nine thousand will not (8100 will get negative test results, and 900 will get incorrectly positive results).\n\nSee? 900 accurate positives, and 900 false positives. If you get a positive, the chance is 50-50 that you have the disease.\n\nThis 50-50 thing is true in this example because I said that 10% of the population has the disease, and 10% of the tests come out wrong. That's why the number of false positives matches the number of true positives.\n\nReal life is rarely like that. So let's change the numbers. Say that now, 30% of the population has the disease. And say the test is still the same, 90% accurate.\n\nWith these new numbers: Of the 10,000 people in the town, seven thousand do not have the disease (6300 will get a negative test result and 700 will get a false positive) and three thousand do have the disease (2700 will get a positive test result and 300 will get a false negative). This means that, if you get a positive, you're one of 3400 people who got a positive, i.e. 2700 real ones plus 700 false ones. So if you got a positive, there's about an 79% chance (2700 out of 2700+700) that you actually have the disease.\n\nThe lesson? If you sample some data, sometimes you can only interpret what that data tells you in light of some other things you know about this kind of data. ([If you get an email with certain words, you can only determine the probability of that email being spam if you know the likelihood that emails with those words are spam](_URL_1_)).\n\nQuantitatively:\n\nLet's look again that that town of 10,000 people.\n\n * Probability of having the disease = 30% (call that **P of A**).\n\n * Probability that the test comes out positive = 34% (call that **P of B**... that's 27% chance of you having the disease AND the test being correctly positive (30% times 90%) and a 7% chance of you not having the disease AND the test being incorrectly negative (70% times 10%)).\n\n * Probability that the test is positive given that you have the disease = 90% (call that **P of B given A**).\n\n * So the question is... what is the probability that you have the disease given that the test came out positive? (call that **P of A given B**).\n\nBayes' theorem says;\n\nP of A given B = P of B given A, times P of A, divided by P of B\n\nIn this case, it's 90% times 30% divided by 34% = 0.90 x 0.30 / 0.34 = 0.7941, i.e 79%.\n\nThis kind of math can be used to quantitatively describe situations where we know that A happened, and we know that A tends to happen when B happens (or will happen), so how likely is it that B happened (or will happen)? If all our data is indirect and probabilistic, the more data we have then the more certain we can be that the truth is what the data indicates (rather than all the data happening to indicate the wrong thing).\n\nI'll link to more information so you can see what I mean: Here's [an interesting real-world example](_URL_2_) and here are [a couple more easy mathematical examples](_URL_0_).\n\nEDIT: Clarity, formatting",
"Frequentists say that probabilities correspond to ratios of actual events. So, you could say that there's a 20% chance of drawing a red ball at random from an urn that has red and green balls in it. You could even say the urn is 20% likely to give a red ball. \n\nBayesians believe that probability corresponds to uncertainty in a mind due to partial information. They would say things like \"I believe that if I draw a ball from this urn, there is a 20% chance it will be red.\" That's pretty similar to what the frequentist would say, but the Bayesian is making it clear that it is his *belief* about the urn, not an property of the urn. After all, if someone with x-ray vision looked at the urn and saw that the ball on top was red, they would say there was a 100% chance of getting a red ball. \n\nThis also means the Bayesian can say things like \"I'm 99% confident the sky is blue right now.\" A true frequentist would gasp in horror at this, because there's no way to view that probability as corresponding to a ratio of frequencies of events in the world. The Bayesian instead simply means that when he says he's 99% confident in something, he expects that 1 out of every 100 times he makes a statement like that, he'll be wrong. \n\nBecause Bayesians view probabilities as estimates of belief, they can do things like ask \"I used to think something was 50% likely, but I now have evidence that it is more than 50% likely. What should my new estimate of the probability be?\" It turns out there is a mathematical rule that tells you *precisely* how much to change your probability estimate, based on how likely the evidence is. It's called Bayes Rule. \n\nFor example, if I think cancer is rare in the population, and I came up positive on a cancer screening test, I can calculate my new estimate of how likely it is that I have cancer. Before I thought it was very unlikely; now it is somewhat more likely, because the cancer screening test comes up positive more often when you actually have cancer; and Bayes Rule tells me exactly how much to change the probability. \n\nTLDR: Bayesian probability is a measure of belief or uncertainty in a mind due to partial information.\n\nNote: Credit to ET Jaynes's book *Probability Theory: The Logic of Science* and E. Yudkowsky's [blog post archive](_URL_0_).\n\nYou might also like these:\n[An Intuitive Explanation of Bayes' Theorem](_URL_1_)\n\n[A breakdown of the previous](_URL_2_)"
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2ydvij | how come there aren't more dinosaur bones? | Shouldn't there be alot more dinosaur bones then we have found? Why did some bones make it to be discovered in this age whilst others didn't? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2ydvij/eli5_how_come_there_arent_more_dinosaur_bones/ | {
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"What we find today are not the actual bones but fossils which are bones replaced by minerals. For this to happen, conditions have to be *perfect*. One condition that's particularly problematic for fossilization of dinosaur bones is that they have to be buried by some type of sediment which for land dwellers doesn't happen all that often. \n\nTL;DR: There were a lot of dinosaurs but fossilization is extremely rare.",
"To add to /u/GermTheory 's comment (which I believe is the correct answer), think about how few bones there are of some existing animals. IIRC scientists have yet to find the complete skeleton of a snow leopard, which is not only rare but also very elusive. There are a few other animals that fall in the same category. So obviously their bones are in some hard to find place and they decompose before anyone finds them. So you can see how easy it is for all body parts to decompose or be eaten by another creature before they fall into a bog pit or get washed under a pile of dirt where there might be a chance of preservation (fossilization)."
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91607t | what are the first things that scientists look for in a planet to see if it may support life | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/91607t/eli5_what_are_the_first_things_that_scientists/ | {
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"I'd say the distance it has from its star and if it has a temperature that supports fluid water. Other important factors are if the planet is rotating around its own axis (important because a locked planet has one side that's too hot and one side that's too cold), the planets mass and atmosphere.",
"When examining other solar systems it is possible to determine the habitable zone around the main star. The habitable zone or ecosphere is the zone in which organisms (similar to the ones on Earth) could exist. \n\nIt is also possible to determine the atmospheric composition of other planets simply by observing the change in light rays emitted from the parent star when they pass through the planets atmosphere. \n\nTypically scientists look for Hydrogen, Carbon and Nitrogen however we know very little about how life is actually created so there could be organisms that can survive in ways we can’t even imagine.",
"At this point, really all we can see about planets outside our solar system is mass and orbital radius. Additionally we can see what kind of star the planet orbits. \n\nThat means all we can really find out is some basic information: is this a giant planet like Jupiter (probably bad for life, though maybe it could be on a moon)? Is it a rocky planet (probably better for life)? Is this so close to it's star that it will fry? So far that it will be in deep freeze? Is the star putting out giant solar flairs or only a few million years old? Really what we do is filter out planets that seem obviously unsuited.\n\nHopefully in the next 20 years or so we'll have telescopes where we can see atmospheric composition of planets, and that will tell us a ton (not just about life, but about planets in general). That's when we start to get the good information. Hypothetically, we may see a whole stack of planets with CO2 rich atmospheres (like Venus and Mars) and then maybe some with atmospheres that look like Earth. That'd be a good sign of life (thought not a perfect one). And we might see some unexpected oddball atmosphere that might represent a different kind of life."
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2z0dn3 | why does a quick fap help me fall asleep? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2z0dn3/eli5_why_does_a_quick_fap_help_me_fall_asleep/ | {
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"Because the succubus that is after you is draining your energy through your penis"
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2n2zw3 | how do countries enforce border control when there is thousands of miles of land that people can use to get in? | There is no way it is possible to patrol the entire border. | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2n2zw3/eli5_how_do_countries_enforce_border_control_when/ | {
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"when you figure it out i'll bet there are a lot of Texans that would be interested to know...",
"True, but some ways are more convenient than others. For one thing, roads. For another, human habitation nearby where one can find shelter, food during the trip. The more porous parts of the border between the US and Mexico are in the middle of a fucking desert. Many people die trying to cross there.",
"one method is simply just build a giant fence/wall (note: US-Mexico; North Korea - South Korea; East and West Berlin when the wall was still up, e.t.c.). Cameras also make patrol easy. Being an island nation also greatly simplifies the problem. The simplest method is just do as Europe does and not enforce borders at all. I can walk from Portugal to Sweden across the entire continent without having to show my passport once. helicopters, hostile terrain, flat terrain and infrared/thermal imaging helps a lot. A single guard post can monitor a surprisingly large area by eye.\n\nBut there isn't any fool-proof method. No system is 100% safe and border control regularly fails: as you might have noticed. If it would be perfect the concept \"illegal immigrant\" would be non-existent. "
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4z6ui4 | how/why have fauna and flora branched out from the first single-cell organisms as separate and vastly different life forms and was there ever a hybrid middle stage between plant and animal? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/4z6ui4/eli5_howwhy_have_fauna_and_flora_branched_out/ | {
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"\"plants\" and \"animals\" evolved as single celled organisms originally. The ancestoral plant cells absorbed another organism with the ability to turn sunlight into energy. Known as cyanobacteria I think, which became chloroplasts inside the plant cell, maintaining their own separate dna.\n\nThe ancestoral animal cells absorbed another microorganism, which lived on in the animal cells as mitochondria, having their own separate dna from their host animal cells. \n\n\nSo given the separate origins of what makes a plant cell and plant cell and an animal cell am animal cell, I don't think there was a hybrid. If there was then it's not alive today, although there are cases in this era where some animals like sea slugs have evolved the ability to house algae in their skin and live off photosynthesis. ",
" > How/why have fauna and flora branched out from the first single-cell organisms as separate and vastly different life forms?\n\nOn a planet saturated with unicellular life forms, whenever there is a niche that opens up (in other words, a habitat that favors a specific life strategy), life finds a way to fill it.\n\nInitially, most of the fuel for life came in the form of sunlight, hydrothermal vents (thanks /u/Prae_), and inorganic compounds. The first forms of unicellular life were capable of extracting energy from these sources to produce organic compounds necessary for its growth and metabolism. Inevitably, this created a new niche for other forms of unicellular life, specificially ones that used predation, parasitism, mutualism, commensalism, amensalism, or other [biological interactions](_URL_1_) as a way of exploiting the efforts of the existing organisms.\n\nThink of it as a gold rush. Once word gets out, prospectors everywhere will be headed to the site, but eventually, some of these prospectors will decide to start various unrelated businesses (ie. clothing shops, restaurants, grocers, barbers, doctors, dentists, etc.) around the mining site to profit off of the other prospectors. Similarly, many forms of life radiated to profit off of other life.\n\n[This diagram](_URL_3_) shows how the major clades (groups of related organisms) branched out. Animals, or metazoans, can be found in the group named Opisthokonta, whereas plants can be found in the group Archaeplastida. The common ancestor of plants and animals probably resembled Apusozoa, Collodictyonida, or Centrohelida but this doesn't necessarily mean that they look like either one.\n\n > Was there ever a hybrid middle stage between plant and animal?\n\nBecause of how far back plants and animals share a common ancestor, there is likely nothing that looks intermediate between a plant and an animal in a genetic sense. In other words, there's nothing that looks like a Bellsprout or Vileplume from Pokemon.\n\nWhile not actually plants, there are some organisms that have plant-like structures and animal-like characteristics. [Euglenids](_URL_0_) and [a species of sea slug](_URL_2_) actually incorporate whole chloroplasts into their cells from their algal or plant-based diet.\n\nEDIT: /u/Prae_ has an excellent response regarding the role of endosymbiosis in the branching out of \"animal\" and \"plant\". Please check out his answer also.",
"Organisms branched out because survival is easier without competition; why compete for the same sunlight and nutrients when you can eat the thing that gathers them.\n\nAs for the hybrid, there are several, in fact an entire kingom called Protista is made up of such hybrids. Protista are mostly single cellular and are able to move, photosynthesize and eat other cells.",
"Most early cells couldn't use sunlight for food / energy... Instead they used heat, such as around lava vents in the ocean or in hot springs like Old Faithful.\n\nEventually, some of them found out how to get energy straight from the sun. Since there was no evolutionary advantage to moving about, they focused on generating more leaves and branches to collect more sunlight, plants.\n\nSome of the others figured out how to use oxygen... But oxygen doesn't carry carbon with it such as carbon dioxide that plants breath. So while plants are able to grow just from air, water, and sunlight, animals who breath oxygen needed to be move around to obtain the carbon needed to grow.",
"Regarding the last part of your question, check out [Euglena](_URL_0_).\nThese are single celled creatures that move around like animals and use energy from the sun like plants.",
"People tend to make the mistake of thinking of evolution the way that it happens in Pokémon, or thinking that humans \"came from\" monkeys, but the reality is that humans and monkeys are derived from a shared ancestor that was neither human nor monkey.\n\nSo there's not an in-between stage when plants evolved into animals, because it didn't happen like that. But *there is* fungus, which shares traits of plant and animal.\n\nI wish I could rattle off the major divisions for you that gave rise to the main groups of organisms that we have today, but it's been a while since I took Biology in college :)"
]
} | [] | [] | [
[],
[
"https://en.wikipedia.org/wiki/Euglenozoa",
"https://en.wikipedia.org/wiki/Biological_interaction",
"https://en.wikipedia.org/wiki/Elysia_chlorotica",
"https://upload.wikimedia.org/wikipedia/commons/2/2c/Eukaryota_tree.svg"
],
[],
[],
[
"https://en.wikipedia.org/wiki/Euglena"
],
[]
] |
||
c0yhj0 | cats usually clean/groom their fur right after eating. how is it that they don't end up sticky and smelly from the food they just eat? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/c0yhj0/eli5_cats_usually_cleangroom_their_fur_right/ | {
"a_id": [
"er9bee8"
],
"score": [
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"text": [
"Well sticky residue usually is the result of sugar, which there is none of in cat food. And cat breath usually isn’t that bad due to low levels of bacteria in their mouth, so there’s not a lot of smell."
]
} | [] | [] | [
[]
] |
||
65yg8d | why do chillies hurt so much? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/65yg8d/eli5_why_do_chillies_hurt_so_much/ | {
"a_id": [
"dge5lpj"
],
"score": [
2
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"text": [
"Basic survival is a competition here. If humans eat the chilis, the seeds may be crushed and so the plant loses out on possible reproductive potential. Because of this, the plant creates chemicals that simulate poisons.\n\nThe body can't put an absolute ceiling on its response to a chemical. At the bottom of the scale, when there's some heat, the body should react. When there's more, the body should react more. This is survival-advantageous. Humans have not adapted to eating huge amounts of spicy chemicals, so the top of the scale has never been moderated."
]
} | [] | [] | [
[]
] |
||
1t2cqy | how much "horsepower" does one modern horse have? | One horsepower is generally defined as 764 watts I figured a car with 300 horsepower is not as strong (or capable of having as much pulling force as 300 horses)
So how much horsepower does a fairly healthy and strong modern horse have (or able to get up to)? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1t2cqy/eli5_how_much_horsepower_does_one_modern_horse/ | {
"a_id": [
"ce3m6gy"
],
"score": [
2
],
"text": [
"a horse can run as fast as around 15hp, while in the long run its more like 1. When their just galloping its like 5hp"
]
} | [] | [] | [
[]
] |
|
3zjlqx | a company going into voluntary administration. | Also, what a receiver and administrator are and their functions in this case. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/3zjlqx/eli5_a_company_going_into_voluntary_administration/ | {
"a_id": [
"cymnhgx",
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"This happens when a company is in financial difficulty and is unable to pay what it owes, and there is not enough income or expected income for it to be able to do this in future.\n\nAn external party (administrator) is then called in or appointed. Their job is to get things either wound up or restructured so that it is viable. This may involve closing some parts of the organization, selling some assets, negotiating with receivers (the people who are owed money, such as suppliers, banks, employees, etc.). \n\nThis negotiation will prioritize who gets money first and likely involves receivers accepting less than the total amount they are owed. This follows the principle of \"getting something rather than nothing\". When people talk about the receiver getting less, they often say something like, they got 80 cents on the dollar which means for every dollar owed to them, they got paid 80 cents ($800,000 rather than a million)\n",
"I once worked for a company that was under administration because they owed vast sums of money to various vendors (and the banks too...)\n\nIt was basically business as usual except there was a woman in the office every day who controlled all spending. I had to meet with her once when my sanitation chemical vendor stopped shipping to us because we owed them $90,000. I had to explain to her that I would shut the plant down if we ran out of chemicals. We were a food plant running deli meats and it was vital that everything was sanitized properly. \n\nShe actually pushed back on me a little, asking how I thought I had the authority to shut down production. I just told her that I would simply tell the USDA inspector that we are unable to follow cleaning procedures and they would shut us down on their authority. \n\nThe bill got paid, I changed jobs within the month, the company shut down within 3 months. ",
"Guessing Dick Smith prompted this post?"
]
} | [] | [] | [
[],
[],
[]
] |
|
1ar56h | if creating something "lactose free" means adding an enzyme, why isn't all milk and yogurt lactose free? | I mean...My lactose free yogurt is exactly the same taste, texture, and I believe has the same dietary benefits as regular yogurt, so why do I have to hunt around for "lactose free" yogurt across multiple stores? Why isn't all yogurt made to be "lactose free"? Would it cause any issues?
And could you add that enzyme to all dairy products? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1ar56h/eli5_if_creating_something_lactose_free_means/ | {
"a_id": [
"c8zze5z",
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"score": [
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"text": [
"Cost is one factor. Adding this to everything would increase the price (versus not adding it). Another factor is that some people might not want to consume this extra ingredient. ",
"Removing the lactose costs money, so there isn't any point in doing it for the people who are not lactose intolerant - whether the milk contains lactose or not will not affect their purchasing behavior.",
"I am not sure about yogurt, but lactose free milk tastes significantly sweeter than regular milk. I think this is because the enzyme added to the milk breaks down the lactose into simpler sugars, changing the flavor profile.\n\nI think yogurt is very low in lactose naturally already, as the live cultures in it actually metabolize lactose, not leaving much behind. I know some lactose intolerant people who have no problem eating yogurt, but have major problems with milk."
]
} | [] | [] | [
[],
[],
[]
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|
41vu7n | why does twitter need a fleet of 3,600 employees to make a website and phone app to share 140 characters? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/41vu7n/eli5_why_does_twitter_need_a_fleet_of_3600/ | {
"a_id": [
"cz5j7mx"
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"score": [
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"text": [
"_URL_1_\n\nI really don't know though. maybe they have a lot of projects, trying to sort out the next great thing and prop-up shareholder value?\n\nwhile a site like wikipedia, which I actually find useful, has 75 employees?\n\nhere was the answer when they \"needed\" 300 people:\n_URL_0_\n\nObviously there are benefits to having an army of people working for your brand if you can pull it off."
]
} | [] | [] | [
[
"https://www.quora.com/Why-does-Twitter-need-300-employees",
"https://about.twitter.com/careers/positions"
]
] |
||
35qjxn | the difference between number layouts on calculators and telephones - any studies that explain the reason why they have different layouts, and which layout minimizes the chance of error? | I find it an interesting topic...calculators start from 7 and end at 3, while phones (even on password screens etc), the numbers are in order from 1 to 9. Any studies on the reason why these layouts were choosen, the reasons why, etc? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/35qjxn/eli5the_difference_between_number_layouts_on/ | {
"a_id": [
"cr6tynq",
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"text": [
"Numberphile made a pretty interesting video about that, [if you have 7 minutes to spare.](_URL_0_)",
"Right so Bell Labratories did a really in depth study on this way back in the day as to which layouts would work better for telephones. They tried Circular, two columns, two rows, all sorts of things. They eventually saw that the 1-9 that we see today on phones was the best and most efficient for people to get.\n\nWhereas computers and calculators already exsisted before the touch tone phones as 7-9 that we still see today.\n\nSo basically, since the two technologies developed at different times through different people, we ended up with different layouts.",
"This may be apocryphal. Adding machines were around before touch tone telephones, and people who used them all day were really, really fast. Early touch tone technology required a slower data entry for the equipment to recognize the numbers, so a different layout was used to slow down people sued to adding machines."
]
} | [] | [] | [
[
"https://www.youtube.com/watch?v=kCSzjExvbTQ"
],
[],
[]
] |
|
2p88jb | why are your kneecaps hairless/ have much less hair than the rest of your legs? | I was in the bathroom at a restaurant, on my phone, and I happened to look at my kneecaps.
Why is the skin on your kneecaps hairless? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2p88jb/eli5_why_are_your_kneecaps_hairless_have_much/ | {
"a_id": [
"cmu9st4"
],
"score": [
2
],
"text": [
"I grow hair on part of my knees, always assumed the bald spots were where the skin stretches more or rubs against fabric."
]
} | [] | [] | [
[]
] |
|
3er5v7 | why are there so many super-weird shows in japan? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/3er5v7/eli5_why_are_there_so_many_superweird_shows_in/ | {
"a_id": [
"cthm83w",
"cthpe93"
],
"score": [
2,
7
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"text": [
"It's only weird to you because of the difference in culture. If you're Japanese you'll be saying the same about Western tv shows.",
"The main reasons I've seen is twofold. \n1. Japan is so outwardly reserved that the weirdness of their shows/advertising/etc. gives them an outlet. \n2. For the most part, only the weirdest stuff makes it out of the country, so it seems to the non-Japanese that they have nothing but absurdity on television.\n\nEdit: [Rachel and Jun did a video](_URL_0_) that touched on this recently and they said that the weird stuff in Japan would still seem weird to the Japanese people."
]
} | [] | [] | [
[],
[
"https://youtu.be/CxUrpUJycuU"
]
] |
||
3407e6 | on video game controllers, why do we move with the left hand and jump/action with the right? | ELI5:On video game controllers, why do we move with the left hand and jump/action with the right? Who decided this? Does it have something to do with the lobes of the brain? Or was it just some arbitrary thing that never changed? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/3407e6/eli5on_video_game_controllers_why_do_we_move_with/ | {
"a_id": [
"cqq198p"
],
"score": [
3
],
"text": [
"Most people are right handed and early arcade games that influenced how controller were eventually designed tended to have the buttons so that you would push them with your right hand and a joystick to move with your left hand (which presumably required less coordination)."
]
} | [] | [] | [
[]
] |
|
eoz9wo | why does liquid nitrogen freeze things so fast? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/eoz9wo/eli5_why_does_liquid_nitrogen_freeze_things_so/ | {
"a_id": [
"feg2mz9"
],
"score": [
2
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"text": [
"Things freeze when they lose enough heat to do so. Heat flows faster between things when the difference in their temperatures is higher. LN2 is *really* cold and so heat flows into it from normal things *super fast*. The result? Things usually freeze really fast when touching LN2."
]
} | [] | [] | [
[]
] |
||
b2cpl9 | when the fbi seizes a domain and a website why do they put an image saying the site has been seized instead of just deleting it completely? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/b2cpl9/eli5_when_the_fbi_seizes_a_domain_and_a_website/ | {
"a_id": [
"eirutcj",
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"score": [
32,
3,
2
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"text": [
"To let people know what they are doing and to put a deterrence in the mind of people who might be using some sites for illegal activities, since the FBI might be tracking their activities.",
"There’s a potential for more data to be captured from those who visit afterwards than they could capture from a DNS lookup for a nonexistent domain. ",
"Due process... what if the seized site is not part of something illegal? The accused has the right to trial where they are fluid to be guilt or not before the site can be shut down completely"
]
} | [] | [] | [
[],
[],
[]
] |
||
fwbbyh | if you shoot a bullet into the sky, how far will it go? | In this case, it would be shot through a Glock 19. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/fwbbyh/eli5_if_you_shoot_a_bullet_into_the_sky_how_far/ | {
"a_id": [
"fmncyn6",
"fmnfk7x"
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"score": [
2,
9
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"text": [
"It depends on the angle you shoot it at, the gun you shoot it with, and many other ballistic parameters.",
"A glock 19 has an expected muzzle velocity of 1250 ft per second. Shot straight up into the air from sea level, the biller should go to a height of approx 24k feet. \n\n_URL_0_\n\nThe bullet will be aloft for about 77 sec if you don’t account for friction."
]
} | [] | [] | [
[],
[
"https://www.omnicalculator.com/physics/projectile-motion"
]
] |
|
u6try | why are there medical marijuana dispensary raids? | Why are there raids on dispensaries? Isn't the entire point of a dispensary that people with cards get them legally? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/u6try/eli5_why_are_there_medical_marijuana_dispensary/ | {
"a_id": [
"c4sss6u",
"c4svjni"
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"score": [
17,
4
],
"text": [
"The state government says they are legal. The federal government doesn't have to honour that though, so they can have the DEA/FBI shut any of them down just because they are illegal by federal law.",
"Well for one their are some dispensaries which are completely illegitamate, the state doesn't like them either. Those ones generally aren't in contention, the state says they have to go too.\n\nThe main reason they get raided though is the Department of Justice and DEA don't recognize the choice of the state to allow marijuana to effectually be treated as Schedule 2 when it is federally Schedule 1. Schedule 1 is when the government does not recognize any medical uses for the drug and it cannot be obtained by prescription or any legal means. Schedule 2 is drugs with high potential for abuse but some recognized usage. \n\nBasically the federal government does not care about what the states decide for marijuana laws, they will raid dispensaries until there is a federal action against it."
]
} | [] | [] | [
[],
[]
] |
|
2rb51b | what's the purpose of the proposer getting down on one knee when proposing? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2rb51b/eli5_whats_the_purpose_of_the_proposer_getting/ | {
"a_id": [
"cne7q8s"
],
"score": [
2
],
"text": [
"It's unclear where exactly it started as a tradition, but just like with medieval Knights its a sign of submission or fealty. The man is pledging himself to his intended."
]
} | [] | [] | [
[]
] |
||
35d4e6 | bernie sanders seems to have a lot of internet fervor reminiscent of ron paul in 2008; for someone who doesn't keep up on politics, why should he have my vote? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/35d4e6/eli5_bernie_sanders_seems_to_have_a_lot_of/ | {
"a_id": [
"cr3b493"
],
"score": [
2
],
"text": [
"Bernie Sanders is by far the most consistent presidential candidate in terms of what he believes in. He has supported gay rights for years, voting no to ban gay adoptions in DC as far back as 1999. Bernie has been against the War on Drugs, voting no on strengthening the laws against drugs since 1998. This is opposed to a lot of candidates who change their views simply so they can garner votes; Sanders fights for what he believes in. \n\nHe has also voted against the USA PATRIOT Act every time he has had the opportunity to, so if you're against mass spying on American citizens, you'll probably like Bernie. \n\nOverall, I don't know all of your specific beliefs, so you should probably decide for yourself, as these points are just a few of the things he is known for.\n\n_URL_0_\n\nYou can also get further information on /r/SandersForPresident.\n\n"
]
} | [] | [] | [
[
"http://www.ontheissues.org/senate/bernie_sanders.htm"
]
] |
||
6jmjaa | what are the mechanics of a passenger jet turning | I was recently on a flight seated above the wing and whenever we turned I would look to see if I saw either the aileron or anything else on the wing move but nothing did. How does a plane begin a turn? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/6jmjaa/eli5_what_are_the_mechanics_of_a_passenger_jet/ | {
"a_id": [
"djfh7iy",
"djfjyo8"
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"score": [
2,
3
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"text": [
"The air moves over the wing very fast so even a slight tilt of the aileron is often enough to start the plane rolling, then when it has rolled or banked enough the pilot can let the aileron go back to normal. You might notice it moving more closer to the ground when the plane isn't going so fast and needs to make harder turns to get the landing right.\n\nThe ailerons on their own don't actually turn the plane much, they just make it bank. The rudder on the back of the plane does the real turning and the ailerons are used at the same time to keep the plane stable. It's kind of like turning on a bike - you can lean to change direction slightly or you can turn the front wheel to change direction faster, but doing both slightly at the same time gives the best turn.",
"The objective with planes is to make coordinated turns. If you turn in your car, the golfball on the dashboard rolls over to the passenger's side. That's someone inconvenient at 30MPH, but a big deal at 500 MPH. To avoid having everybody's drinks spill, the pilot rolls the plane a little as they turn. This makes \"down\" remain the same direction from the passenger's point of view, and fewer people get airsick. There is a special instrument in the cockpit that displays \"down\" so the pilot can control it precisely. At cruise speed, only very small deflections are needed to make smooth rolls to match the rudder inputs that control the turn. The only time you need those big control surfaces is for crosswind landings."
]
} | [] | [] | [
[],
[]
] |
|
1xbzr0 | why can i only think in my own voice? | This might sound like a dumb question... in fact I predict many downvotes but back to the topic at hand I can only think in my own voice be it my own natural voice or my own voice micking someone eles' as I would if I was making fun of them. The question is why? A more detailed question: if I don't need vocal cords to think (presumeably) why can't I make a noise I cannot physically? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1xbzr0/eli5_why_can_i_only_think_in_my_own_voice/ | {
"a_id": [
"cf9z8pm",
"cfa1554"
],
"score": [
2,
3
],
"text": [
"Speak for yourself; I hear [Christopher Walken](_URL_0_) when I think. ",
"This isn't a dumb question by a long shot and it might surprise you to learn that you do have some control over the voice characteristics of your internal dialog. In fact, it is the basis of some therapy techniques.\n\nI used to be a hypnotist by trade and I found that helping others to explore and change their inner voice worked extremely well for people who complained of low self esteem. \n\nYou might [find this interesting](_URL_0_) to read.\n\n"
]
} | [] | [] | [
[
"http://www.youtube.com/watch?v=l7E_j49762Q"
],
[
"https://sites.google.com/site/liveabrighterlife2/internaldialogue"
]
] |
|
15rb3g | the atheistical argument against evolution | Recently heard some guy in a restaurant saying that "evolutionary theory just didn't convince him," and later in the night, just as loudly, "I'm an atheist, so I don't believe in stuff like that" about something else.
Any ideas? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/15rb3g/eli5_the_atheistical_argument_against_evolution/ | {
"a_id": [
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"text": [
"Technically, there is nothing requiring someone who is an atheist to also believe in evolution. However, evolution is the most complete explanation for how species came to exist. This person likely does not have a coherent competing explanation. He simply \"isn't convinced\" by a theory that he likely doesn't understand very well.",
" > Any ideas?\n\nApart from being ignorant or just confused, he may believe that life on Earth was created by another, extra-terrestrial life form, for example.\n\nIn any case, there is no 'atheistical argument against evolution' in the strict sense."
]
} | [] | [] | [
[],
[]
] |
|
a5rasc | how to tell if compound has nonpolar/polar bonds & molecules? | Hi! My chem teacher has tried to explain the process of telling us how to identify polar vs nonpolar bonds (right before our test of course lol) but his explanations are conflicting. Someone please explain! Thank you! | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/a5rasc/eli5_how_to_tell_if_compound_has_nonpolarpolar/ | {
"a_id": [
"ebosasj"
],
"score": [
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"text": [
"Think of tug of war. Both atoms have a hold of one side. Electronegativity, a property of the atoms, determines the strength of the people playing tug of war. A more electronegative atom, the stronger the pull on the rope. \nA polar bond is one in which the two atoms strength are different. A non polar bond means that they have the same strength, and the fight is even.\n\nNow in a molecule, just add all of these atom atom interactions up. It’s a giant game of tug of war. Non polar molecules are where the giant tug of war results in a net stale mate. Polar means one side is winning. \n\nWhenever you have a polar bond, you get a dipole moment, a vector of difference in charges is formed. Add all of the vectors up, and you get a combination of vectors. If that combination is zero, then the molecule is non polar. If there is a leftover vector, then the molecule is non polar. "
]
} | [] | [] | [
[]
] |
|
6scwhq | why do aircraft use flaps to take off? doesn't it create drag? | Judging by the aileron/elevator movement, the flaps should point the aircraft's nose towards ground, but it doesn't. ELI5. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/6scwhq/eli5_why_do_aircraft_use_flaps_to_take_off_doesnt/ | {
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"The fact that the larger wing surface creates more drag is precisely why aircraft use flaps. Flaps allow the wing to only be that shape at certain periods of flight.\n\nAt the slower speeds of take off and landing, the lift it generates is much more beneficial than the drag it creates. At higher speeds the drag would become an issue, which is why the flaps are retracted at cruising speeds.\n\nWithout flaps, aircraft would have to land and take off at higher speeds and lower weights, meaning less passengers/cargo/fuel, and longer runways.",
"It does create drag. You simply increase thrust. However now the increased lift of the wing allows the plane to maneuver at slower, safer speeds than it would otherwise.",
"Two methods of increasing the lift force of a wing. More speed or increased pressure difference by making the air over the top half of the wing slower. The flaps increase the \"angle of attack\" of the wing which in turn extends the travel time of the air over the wing. This increases lift but also increases drag. \n\nDrag itself doesn't stop the plane from flying but makes it less efficient, requiring more fuel to push the aircraft through the air. At slower speeds you need a greater angle of attack to get the lift required for flying. At higher speeds the lift of wing without the flaps is enough so you remove the flaps to decrease the drag and make the aircraft more efficient \n\nThis is why an aircraft sounds like it's about to bust a gut to takeoff and uses significantly more fuel for takeoff and landing than for flying. "
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8ckp32 | how does captcha both screen bots and build machine learning databases? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/8ckp32/eli5_how_does_captcha_both_screen_bots_and_build/ | {
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"They have a database and part of the key.\n\nThey show you 4 signs, 3 they are sure of and 1 maybe. If you get the 3 they know right, then your vote counts for the 4th one. If 500 users who got the 3 known signs right agree about the 4th one, that's pretty good evidence that their answer is the right one. Add that sign to the database and put the next unknown one into the captcha."
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97g355 | what does it mean when a judge says “with prejudice” after they announce the result of a trial? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/97g355/eli5_what_does_it_mean_when_a_judge_says_with/ | {
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"The case/charges cannot be refiled. For example. Let's say a criminal has 4 counts of drug possession on a case. Since attorneys really don't want things to go to trial, the defendant takes a plea deal from the state, where he pleads guilty to 2 counts and the other 2 are dismissed with prejudice. That means they cannot try and convict him for the 2 counts that were dismissed. Alternatively, sometimes the state moves to have a case dismissed without prejudice so they can refile it for slightly different charges.",
"The answers above are correct but I would add that its easier to see why it means what it means when you know that it sometimes written out more fully such as \". . . the Motion is denied without prejudice to the refiling of the same\" if the motion at issue isn't being denied on the merits but on a procedural ground (like it was filed too soon or the like). In this instance the court is saying you can refile your motion and it won't be \"pre-judged\" by the earlier motion being denied. A dismissal of a case with prejudice means that the same case will be 'pre-judged' by the result in the first case."
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6w6h07 | fata morgana: what is it? how does it occur? | I know that Fata Morgana is a type of mirage, but what can you see in this kind of illusion and where/how does it occur? Is it just a distorted image of something on the horizon? Or would you normally not even be able to see that object?
I can't understand anything that the Wikipedia page says on the topic. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/6w6h07/eli5_fata_morgana_what_is_it_how_does_it_occur/ | {
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"You're seeing something near the horizon or beyond the horizon.\n\nYou can see beyond the horizon because light \"bends\" towards colder air. If there is cold air at the ground and warm air higher up, this will cause light to bend downwards, guiding it around the curve of the earth. So under those conditions you can see objects much farther away than normal.\n\nIf you want to see one, you need to go to a place where there is cool air at the ground and warmer air higher up. You also need it to be a place where you can see all the way to the horizon, and there has to be an object over the horizon for you to look at. These conditions happen, for example, at the edges of bodies of water at the beginning of summer, when the air is warm but the water is cold."
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25gbqs | if scientists have warned us about the west antarctic ice sheets collapse and other severe global warming effects, why won't major world governments like the united states or china do or have done anything ? | If we see evidence of global warming before our very eyes (an entire artic ice sheet going slowing into the ocean) why won't governments do something about it especially something very catastrophic to the world ? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/25gbqs/eli5_if_scientists_have_warned_us_about_the_west/ | {
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"Because of the Almighty dollar. To make the necessary changes it would cost businesses money.. or as the Republicans like to say \"It will cost jobs\" \nI personally would rather lose my job than lose my life, but that's just me. ",
"Voters are more concerned with financial gain and the possibility of an economic recession, due to their relatively immediate effects, than they are with environmental problems, which generally occur over a very long-term period of time. Furthermore, a small but incredibly vocal percentage of the population erroneously believes numerous environmental problems are a hoax, and a larger percentage of the population blindly believes that an unspecified, or vaguely described technological development will magically solve the world's environmental problems.",
"Facing up to climate change is something that requires international co-operation, and this is something that is very hard to achieve. One reason is the free rider problem. Say a group of countries sign up to a reduction in CO2 emissions, but that, at least in the short run (say), this leads to a cost either in government spending or GDP reduction, or just voter popularity. From the standpoint of any one country, it makes sense to not follow that agreement, assuming all the others keep their word and stick to it. This is because they'll get all the environmental benefits of the other countries reducing CO2, but none of the costs on themselves. \n\nWhat makes this even more troublesome is that countries that face the most immediate threat from climate change through drought or rising sea levels (a lot of African nations) aren't the ones producing most of the pollutants. So the developed nations producing the pollutants face far less risk to themselves if the whole deal falls through. \n\nFurther, this might all seem daft if you take the long-run perspective, but governments, particularly in democracies, are by nature inclined to focus on the short-run. This is because there's not much point in a government taking a hit in popularity now by putting through potentially unpopular environmental policies (tax on carbon fuels, for example), if they won't be around to receive the benefit after the next election (or several elections). "
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2789ja | how can a private company like spacex launch a rocket for so much less than a government run agency like nasa? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2789ja/eli5_how_can_a_private_company_like_spacex_launch/ | {
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"It's hauling less mass, it's only reaching low earth orbit, there's less overhead because the company is much smaller and it's a private enterprise vs a government agency.",
"Because NASA is publicly funded, there's a certain amount of beauracracy that is inherint and required. you need liasons with congress. Your bidding process has to be open and transparent.\n\nSpace X doesn't. They can say, I need 4,000 widgets, who can give me the lowest price? You? Done. When can you deliver them?\n\nAlso, they aren't forced to use the same vendors that NASA - whether by government pork barrel spending or just tradition - typically uses. Lockheed, Gummen, Boeing etc.\n\nThats not to say that the new NASA isn't capable of running closer and leaner to what SpaceX can... they probably could, its whether they'd let them.\n\nPlus too, your NASA dollar pays for a lot of other stuff. Research centers that are working on not just getting to the ISS, but future things. How can we grow soybeans during a trip to Mars for example... whereas SpaceX's only goal is get stuff/people into orbit. For now.",
"Simply put, bureaucracy is expensive. ",
"Addiotnally what has been said by other poster, the rockets used and the requirements to them can be vastly different. A rocket to carry a several billion worth interplanetary mission will have much higher costs in terms of safeguards, ground operations etc as the tax payer really does not like to see an expensive firework. From what I understand if SpaceX will get a contract for goverment satellites (NRO, etc) their prices will go up. There a lot of factors in spaceflight as it is interwoven of goverment and industry which can get the price up signifanctly. Also big flagship missions are one of a kind which reduces the amount which can be saved by economy of scales.",
"I'd like to add that people are failing to remember the cost of research. A company like SpaceX is doing what NASA had to research and develop decades ago.",
"SpaceX would not be able to do it for that cost if NASA hadn't existed before it. NASA spent decades doing research and engineering work solving problems (in many cases, finding out what problems even needed solving). SpaceX can piggy-back on a lot of that fundamental research. Not that SpaceX isn't doing quite a lot of advanced engineering on their own, but they are building upon the foundation laid by NASA.\n\nNASA funding is also a gravy-train for Congress. Parts and expertise are sourced from all 436 congressional districts. A profit-minded company would centralize operations, whereas in our federated funding model, each individual Senator or Representative cares about jobs being created in their own district, even at the cost of overall efficiency. I mean c'mon... launch from Florida, but Mission Control is in Houston? That's just silly.\n\n[More reading about some of the specific engineering trade-offs](_URL_0_). Of note: The original cost-benefit analysis planned to ammortize the fixed costs over many more flights, as much as one per week. Instead it launched a few times per year. The infrastructure and construction costs staid basically the same, and the Shuttle was basically wildly over-engineered, to be able to withstand much more usage than it actually saw.",
"You answered your own question. ",
"much less buerocracy. nasa became highly buerocratic.",
"I recently did a tour of SpaceX with a friend of mine who works there as a propulsion engineer. He says that its because everything there is made in house. \n\nWhen i went on the tour to their factory i really just expected it to be a big office building (Redondo beach isn't a city known for factories). But they were actually building rockets right there in front of my eyes. Everything (mostly) is done right there in that factory. No contracting out to other companies who will make profits on what they sell you. ",
"Here's a few notes on the difference between what NASA has done so far and what SpaceX has done so far:\n\n1. SpaceX didn't have to invent orbital rocketry. NASA did.\n1. SpaceX didn't have to figure out what happened to the human body in space. NASA did.\n1. SpaceX gets to use computers to do modeling and simulation. NASA had to use slide rules, large groups of engineers, and actual experiments. If NASA wanted to test an idea, they would have to *build an actual rocket and try it out*.\n1. SpaceX gets to use NASA's old data. NASA had to figure it out in the first place. A lot of those things, NASA figured out by putting things into space then observing them carefully for months or years to see how they held up.\n1. So far NASA and SpaceX have been playing for different stakes: SpaceX has only done cargo runs to the ISS, but NASA has flown humans to the moon and back. With no risk of human life, SpaceX can take different risks than NASA could.\n1. SpaceX isn't just using technology NASA invented, it's using technology from all over the world, particularly from commercial satellite launches—again, a field where there's valuable cargo at stake, but no human lives.\n1. NASA designed, built, launched and assembled most of the ISS. SpaceX is just running a back-and-forth cargo service.\n1. Not only has NASA has carried humans into space, but NASA has figured out how to keep humans alive (and healthy) in space for months at a time.\n1. SpaceX hasn't been saddled with the ungodly boondoggle that was the space shuttle program. STS invented a lot of interesting technology, but it had a 40% vehicle failure rate: five were built, two blew up, killing everyone aboard.\n1. NASA didn't have access to the Soviet space program's extensive research and findings. SpaceX does.\n1. Speaking of the Soviets, NASA was engaged in what was, at the time, thought to be a \"fight for the high ground\", where two nations—who were kinda-sorta at war—were trying to get the upper hand on each other. In this space race, whoever won got to drop atomic bombs on whoever lost. This has a different sense of urgency than a speculative commercial venture.\n\nThat's all I can think of for now."
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asgfeu | why is our dishwasher unable to remove raw protein from dishes? | [deleted] | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/asgfeu/eli5_why_is_our_dishwasher_unable_to_remove_raw/ | {
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"Meat is *Carbon. Carbon is tiny and has a grip fills the poors of a plate when heated. Heat makes the carbon expand (excite) Think of how dense an icecube is vs water. the thing is that when cooled the carbon solidifies. Some of these make barbs(grip) the plate. I've been a dishwasher in 5 restaraunt kitchens (Soaking plates does not help and is a wives tale) You've got pry, then lightly scrap (soft spoon) Blast, Scrub Blast. If you have alot of water pressure it helps. I hot water blast, cold water rinse. But there is alot of other little tricks, this is just the a few. Salt is helpful too.",
"Meat *does* get tougher with cooking. Ever tried an over cooked steak? How about a piece of chicken left in the broiler for too long?\n\nAs far as 'warming up' before strenuous exercise, you're less prone to injury not because of temperature but because you've induced stimulation and stretching to your muscle groups, thereby waking them from their ordinary dormant state.",
" > \tbut I know that's not true, because cooking meat doesn't make it tougher\n\nWait, I assume you work in food service due to the use of a dishwasher so I don't see how it could possibly have escaped your notice that a \"well done\" steak definitely does get tougher."
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d5osoy | if electricity is just a flow of electrons then why is electricity considered energy instead of mass? what even is 'energy'? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/d5osoy/eli5_if_electricity_is_just_a_flow_of_electrons/ | {
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"Electricity is the *movement* of electrons not the electrons themselves. Think about the power in a rotating drive shaft out of an engine to move a car, is that just \"mass\" because the rod is made of material?\n\nEnergy is in the sense of physics the ability to do work. Consuming electricity doesn't consume the electrons, it consumes the force of their flow.",
"Because electricity isn't the electrons themselves, it's the *movement* of the electrons in a current. Energy is the ability for a physical system to do work, meaning to make some change to its state."
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p10qd | how do cats recognize people and how long do they remember them for? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/p10qd/how_do_cats_recognize_people_and_how_long_do_they/ | {
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"One way is smell. A cat's sense of smell is superior. Cats mark objects -- either by urine-spraying (which is normally preventable if the cat is neutered) or secreting scents from glands from their cheeks and paws -- as a way of leaving their scent behind to show \"ownership.\" That's why they rub around your legs and all the furniture in the house.",
"Why don't you subscribe to catfacts?",
"Three ways:\n\nCats can recognize you by smell, their smell is very good.\n\nThey can also recognize you by sight, but they are not as good with faces as most people. \n\nThey also recognize you by behaviour. For most cats, how you behave is more important than who you are.\n\nA cat brain isn't all that different from a human brain, many things (like how they recognize people) work basically the same way. \n\nThere are a few differences. Unlike people, cats remember things from a very young age. Also, cats are not very intelligent, so they think of most people by profession, like you would recognize \"pilot\" or \"police officer\", the cat remembers \"food provider\" and \"guy who throws water balloons at me\". \n\nA cat **can** remember a specific person, but because of the way cats behave, you only notice when you train them for it.\n\nCats do not forget anybody they know well. Their memory is the same as a person's memory in that they can forget important things or remember trivial things from long ago. If you leave an impression they'll remember you their whole lives. The easiest way to do that is to hurt them or make them mad at you. ",
"I recently had to give my cat to my mother (long story). I visit mother once a month or every other month (due to the distance). When I first saw my cat after a month of not seeing her, after seeing her every day for 3 years, she ran away from me at first. When I tried to slowly reintroduce myself to her, she seemed to remember me and started meowing and rolling around and rubbing against my arm.\n\nDid she actually remember me or was she just acting friendly like she does with everyone after a short while? Does she still love me? :("
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3i13ye | what causes the burning sensation in your mouth whenever you eat hot wings? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/3i13ye/eli5_what_causes_the_burning_sensation_in_your/ | {
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"The chemical is called capsaicin.\n\nYour mouth (like the rest of your skin) has nerves that are sensitive to heat. Capsaicin causes those nerves to be super sensitive, until your own body heat activates them. Suddenly, your normal 98.6 degree mouth feels like it's on fire.\n\nThe same thing happens with menthol (the stuff in minty things that makes your mouth feel cool). Your cold-sensitive nerves are made more sensitive, so the normal air feels very cool."
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1wwk12 | what is the r/theredpill/ subreddit all about? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1wwk12/eli5what_is_the_rtheredpill_subreddit_all_about/ | {
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"It is a subreddit based on the general belief that women have it better than men. They believe that male oppression of women is a myth and that society actually is the opposite - women are running the show. Some would argue it is misogynistic. At other times it looks like a dating tips subreddit for men, because a lot of the discussion is about meeting women and similar social situations.. \n\nI am not a member or regular commenter there but I ran across it and had the same reaction you did. Maybe one of their regulars can correct whatever I got wrong? I really didn't investigate further to determine if what I believed about it was correct. I basically learned enough to know it wasn't my thing and moved on",
"feminism changed the sexual dynamics between men and women, on a massive scale. trp offers a nihilistic framework in which these changes can be discussed, particularly from a male point of view.",
"It's a group of men who believe they have uncovered the real rules by which human sexuality works. They believe that men have been deceived by society, especially by femenists, into a false model of how it works, allowing them to be exploited by women. They use the red pill/blue pill analogy from The Matrix, in which they choose to swallow the \"red pill\" that opens their eyes to the truth, rather than the \"blue pill\" of being trapped in what the red-pillers view as an elaborate, though largely undirected, deception.\n\nPeople, myself included, take issue with them for several reasons: \n\n* Some just don't like their ideas and dismiss them out of hand, feeding the whole \"red pill / blue pill\" story. \n\n* Others are disgusted by how bitter and hateful many of their posters are.\n\n* others take issue withhow broadly they generalize people, especially women. Some claims they make are that women are incapable of loving men, that all or at least a vast majority of women are all attracted to the same qualities, that a man can never let his guard down (\"lose frame\" is their phrase I think), that men ultimately only want (or should want) sex from women, particularly fertile sex.\n\n* they provide little to no evidence for their claims beyond personal anecdotes and sob stories, of which they have many\n\n* they distort scientific theories, especially evolution, into philosophies about human purpose and the meaning of life (we exist solely to pass on our genes), which is something that science can't and was never meant to provide.\n\n* they divide all male behaviors into narrow \"alpha\" (desirable) and \"beta\" (undesirable) categories, ignoring the breadth of life and relationships in which those distinctions are meaningless.\n\n* they lose sight of the context of attraction. Even if they were right about how attraction works, they ignore any higher concerns that supercede sexual success.\n\n* some people who accept generalities about human sexuality and behavior in general might not buy into the specific \"red pill\" story or their specific theories, but the whole \"red pill\" idea is inherently closed to self criticism - after all, they are the ones who opened their eyes, what do the beta drones or femenist agents have to offer?\n\n* anything they get right, such as the importance of self-improvement (in general, and when they get the specific forms of it right) can be found elsewhere without all the baggage\n"
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7n2kmz | why vision gets distorted when hot and cold air meet | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/7n2kmz/eli5_why_vision_gets_distorted_when_hot_and_cold/ | {
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"Light travels at a slightly different speed through hot air than through cold air. This causes the light to bend, like it does in a lens.",
"Great question!\n\nI guess you can start with thinking about what temperature is. When something is hot, the particles in that material are moving faster on average than the particles in something that's cold. Because the particles are moving faster, they bump into each other more frequently and tend to have more space between any two particles. When things like gases (for example) are transparent, they can slow down light and bend it by an amount which is directly proportional to their density. \n\nSince a hot material like hot air has more space between its particles, it has a lower density than cold air, and they both bend light by different amounts. When the two gases mix, they make images seen through the mixture appear distorted as all the rays of light coming from some object behind the mix aren't traveling parallel. \n\nI should say that I have no idea why exactly light bends when it passes through a material boundary at some nonzero angle from the perpendicular, so I might go start my own ELI5 post.\n",
"A good comparison is to the surface of a body of water. Since light travels differently in water and air, you can see the barrier between the two clearly. \n\nThe same exact thing happens with hot air and cold air. The light is traveling differently through the two, so you can see the area where they mix. The mixing of hot and cold air can even resemble the shimmering of water since air is a fluid (fluid means something subtly different from a liquid) and moves in a similar fashion to water",
"The same reason a straw appears broken in a glass of water.\n\nHot and cold air have different index of refraction, causing light to travel at different speed. This difference cause the rays of light entering the mixture exit at different angles.\n\nWatch this video:\n\n_URL_0_\n\nExtra fact: the same principle of Snell law also explains how optical lens like those in eye glass and telescopes work by bending light. ",
"Light travels at a constant speed in a vacuum only. In materials, it slows down. If it transitions from one material to another *at an angle*, it bends to a new angle based on that incident angle and the relative refractive indexes.\n\nThe refractive index is how much slower light travels than a vacuum. By definition, vacuum is always exactly 1.0. Glass is as high as 1.5, light travels 2/3rds the speed in glass. Which is why you can make a lens, bending the light!\n\nDiamond is 2.4, thus it bends light in remarkable ways, which is why we value it.\n\nAir at 0C 1atm is 1.000293... only a SMALL amount of difference over a vacuum. At 25C 1atm, it drops to 1.000277. Also water vapor- dry, not cloud droplets- has a different refractive index (can't find it). These aren't very noticeable close up unless the air is VERY hot (gas stove burner), but hot air does create dramatic mirage effects across large distances.",
"Light travels and bends differently depending on the thickness of stuff. Hot and cold air have different thicknesses. When they meet things get wonky. \n\nUsing “thickness” in place of “density”",
"Snell's Law. Light *always* travels the path of leaat time. Just like how light is \"bent\" when entering water, the difference in density (how close atoms/molecules are together) affects the path of least time. Imagine you're knee deep in mud and there is a road a few feet away from you with a finish line at the end. You and a friend want to race to the finish line. Do you run straight to it through the mud or take a different path to get to the road where you can run full speed?\n\nHere is an excellent video [3blue1brown](_URL_0_)\n\nFor the untrusting: _URL_0_",
"Imagine light hitting a glass block at an angle. It refracts as it enters due to a change in speed due to a change in density. Like a lens.\n\nAt different temperatures, you get different density air, so as light passes through, it refracts in a similar manner to above.",
"Great question! I am a aerospace engineer working on a field called Aero-Optics. We study essentially this phenomena. This occurs because as two glasses of different temperatures mix, the mixing becomes turbulent. The turbulent mixing causes density to fluctuate throughout the fluid. Fluctuating density manifests and fluctuating index of refraction. Index of refraction dictates the speed of light through the medium. You constantly have different small pockets of varying density that are changing in both time and space. This causes the waviness. This is ALSO what causes the “mirage” affect of a road on a hot day, or the “waviness” about a flame. ",
"Visible light, like most things, likes to go in the path of least resistance. \nIt goes faster in hot, less dense air. If there is cold air mixed, like when you open the front door to -10 degrees, it is a mixture making a noisy \"wavy\" distortion. You also see this above a candle burning or a jet engine's exhaust. \n \nSimilarly, on hot pavement, the distant road looks like a watery mirage because light is being bent to the path of least resistance, down towards the hot pavement then back up to your eyes creating that weird effect. ",
"Because of two things: \n1. Light travels at different speeds through different material (hot air is different from cold air), \n2. Light moves as a wave, so this happens _URL_0_",
"I've seen the same thing at the confluence of fresh water running into sea water while scuba diving off Kauai. At first I thought my vision had a problem until we swan out a ways from a small lagoon. Kauai has one of the biggest rain falls in the world and all that fresh water running into the ocean causes the optical turbulence."
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e066ny | how do games display a millisecond counter if the max frame rate of a normal display is 60? | There’s simply not enough frames to display the millisecond digit but lots of timers do it anyways. Are numbers skipped? Are numbers blurred together? Is this hard coded by programmers or is it coded to just output milliseconds and whatever numbers happen to align with the refresh rate is whatever shows up? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/e066ny/eli5_how_do_games_display_a_millisecond_counter/ | {
"a_id": [
"f8c4rpz",
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"score": [
21,
14,
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"text": [
"The clocks can count in milliseconds, the screen can't show it. So what you see is typically the time the frame started to draw.",
"The timer keeps count, but the display only updates 60 times per second. The time itself is kept as accurately as the computer is capable of.",
"Are you asking about the decimal points of a frame? As in 55.3 frames a second as one example?\n\nIf so there's a very simple explanation for it. The game is not measuring anything about your display at all. It's measuring what your GPU is doing. GPUs are incapable of outputting frames at even numbers. That's not how they work. They're immensely complex hardware and draw an image as fast as they can. This will never be a round number. \n\nAs to this question:\n\n > Are numbers skipped?\n\nNo. Frames are merged together. The display will simply draw what's in the GPU's framebuffer at specific intervals, and because the GPU does not render images at fixed intervals you'll get half of a new frame and half of an old frame stuck together. This is what tearing is, if you've ever played games with VSync off. That's what that decimal point is in visual terms. You're actually seeing the GPU render at uneven intervals.\n\nThere are ways to avoid this tearing that is caused by how the GPU works. One of them is to stall the GPU and let the display be able to poll the GPU framebuffer when the framebuffer has a single contiguous frame, but this slows the GPU down and introduces latency. This is called VSync, short for vertical synchronization. It's an option you can flip in every modern PC game, and on console games it's most of the time forced on, though there are certain console games that dynamically turn it off. I know Mass Effect Andromeda for a fact does this.\n\nAnother way to avoid tearing is by having a display that is able to draw images at uneven intervals, meaning a display that can change its refresh rate dynamically, so that it can synchronize exactly with how often the GPU draws images. These are called Freesync, G-Sync, or Adaptive Sync displays, and they're relatively new to gaming. They fix the issue of tearing without having to stall the GPU and introduce latency and performance hits."
]
} | [] | [] | [
[],
[],
[]
] |
|
1paiav | why can't high complex organisms asexually reproduce? | title | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1paiav/eli5_why_cant_high_complex_organisms_asexually/ | {
"a_id": [
"cd0dxpe",
"cd0dzwl"
],
"score": [
8,
3
],
"text": [
"Because sexual reproduction produces more genetic diversity and therefore stronger genetic health. We evolved out of asexual reproduction.",
"Some actually can. It's called parthenogenesis. If you've seen Jurassic Park, it was used as a plot device.\n\n_URL_0_\n\nBut yeah, sexual reproduction is usually considered \"better\" because it has the potentially for creating a lot more variability, and therefore, adaptability."
]
} | [] | [] | [
[],
[
"http://en.wikipedia.org/wiki/Parthenogenesis"
]
] |
|
4dn9u5 | why when we're falling asleep and hear a sharp/loud noise does our vision go white? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/4dn9u5/eli5_why_when_were_falling_asleep_and_hear_a/ | {
"a_id": [
"d1sj1yy",
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"score": [
5,
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2
],
"text": [
"Thats never happened to me?... you should get that looked at",
"Yes! This happens to me all the time! I do not have a TV in my room and I prefer to sleep in total black and silence. If there is a sudden noise (house settles/cracks) while I am trying to sleep, I will see (with closed eyes) a brilliant white flash AS the sound is happening, in synchrony. I thought it was normal until I started mentioning it to others and got the WTF face...",
"I just need to be in the dark and if I hear a sudden noise that startles me, I see a geometric grid pattern of stars and/or lines. It's like an instant, very brief hallucination. ",
"It's called Exploding Head Syndrome (EHS), and we don't really know why it happens. It's possible there are multiple different causes for the few people who suffer from it, and we don't know if there's a physical mechanism behind it or if it's mostly \"in your head.\" It hasn't been studied well enough (as the relatively informal name might suggest).\n\nI've never experienced it myself. One study suggested up to 20% of the population have experienced it once in their lives, but it's generally been considered a rare condition.",
"i've never experienced that, but i'd hedge my bets on it being directly tied to survival instincts. at the end of the day, everything our bodies do is done with the primary goal of keeping us alive. if you're falling asleep, and are therefore vulnerable, hearing a loud noise - which the brain may automatically consider a danger before processing that it isn't - may make your pupils automatically dilate and put your brain on higher alert than it was, in order to protect you from the potential threat. in turn, the natural light passing through your eyelids may temporarily be perceived as very bright, before the brain readjusts and processes the information. ",
"I experience this on a regular basis. When im in bed and trying to sleep the lights above me will sometimes make cracking noise or the bookshelf or the floor and i see a white flash and im laying there like wtf and sometimes i will experience 2-3 flashes. So weird! I did not experience this when i was growing up but the last year or so this is a recurring thing."
]
} | [] | [] | [
[],
[],
[],
[],
[],
[]
] |
||
1zpcxc | what is this philosopher saying? | Extract: **Paul Tillich - The Shaking of the Foundations (1948)**
‘The state of our whole life is estrangement from others and ourselves, because we are estranged from the Ground of our being; because we are estranged from the origin and aim of our life. And we do not know where we have come from or where we are going. We are separated from the mystery, the depth, and the greatness of our existence. We hear the voice of that depth, but our ears are closed. We feel that something radical, total, and unconditional is demanded of us, but we rebel against it, try to escape its urgency, and will not adopt its promise. We cannot escape, however. If that something is the Ground of our being, we are bound to it for all eternity, just as we are bound to ourselves and to all other life. We always remain in the power of that from which we are estranged. That fact brings us to the ultimate depth of sin; separated and yet bound; estranged and yet belonging; destroyed and yet preserved; the state which is called despair. Despair means that there is no escape. Despair is “the sickness unto death”. But the terrible thing about the sickness of despair is that we cannot be released, not even through open or hidden suicide. For we all know that we are bound eternally and inescapably to the Ground or our being. The abyss of separation is not always visible. But it has become more visible to our generation than to the preceding generation, because of our feeling of meaninglessness, emptiness, doubt and cynicism – all expressions of despair, or our separation from the roots and meaning of our life. Sin in its most profound sense, sin as despair, abounds among us.’ | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1zpcxc/eli5_what_is_this_philosopher_saying/ | {
"a_id": [
"cfvpo2z"
],
"score": [
3
],
"text": [
"We're born not know if there is an afterlife. All we can do is guess and hope there is more, and without knowing expect the bleakness that is death. Expect that we will never know why we were born to expect death, only that it is a fact."
]
} | [] | [] | [
[]
] |
|
9sk4lm | why does spray paint give us headaches? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/9sk4lm/eli5_why_does_spray_paint_give_us_headaches/ | {
"a_id": [
"e8pehpw"
],
"score": [
2
],
"text": [
"Short answer: Lack of oxygen. \n\nSlightly longer answer: The air you breath in is a certain mixture of gasses that our body can process. Fumes from the paint throw off that mixture. Meaning your not getting enough air and your body is trying to process things it’s not meant to. "
]
} | [] | [] | [
[]
] |
||
4l7k63 | how do "dead" mmos stay in business and afford to continue running? | As far as I know, MMOs are one of the most expensive projects for a studio and is usually resource intensive in terms of ~~server maintenance~~ costs including labor. How is it possible for there to be so many MMOs out there with very few players yet manage to afford production and persistence? If these assumptions are true, I can't see how a few hundred subscriptions or micro-transactions could possibly create enough revenue for an MMO's survivability... meanwhile other MMOs do get shut down for that very reason. How is this so? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/4l7k63/eli5_how_do_dead_mmos_stay_in_business_and_afford/ | {
"a_id": [
"d3kzh2h",
"d3l1o93"
],
"score": [
7,
3
],
"text": [
"Well the companies downsize their servers; potentially down to one actual server. The cost to keep that one server running is probably a lot less than a few hundred subscriptions / micro transactions a month. There's no point in taking it down if the company continues to exist, because you're making money off it by essentially doing nothing, it's already up and running.",
"It depends on the company. If the developers and publishers have other games that generate revenue, they may be able to afford to keep a couple servers running on an old game. For instance, Guild Wars would not be able to run if Guild Wars 2 wasn't doing as well as it is. I bet blizzard would be able to afford to keep a WoW server up for a while if it lost its player base. With no developers and very few servers running, it is more affordable"
]
} | [] | [] | [
[],
[]
] |
|
3e9eph | as i'm going grey, why are there no hairs that are part black and part grey? | I have about 50/50 grey/black hair. But it's obvious a black hair falls out before a new grey one takes its place. Why does it not change midway through growing? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/3e9eph/eli5_as_im_going_grey_why_are_there_no_hairs_that/ | {
"a_id": [
"ctcxm5j"
],
"score": [
8
],
"text": [
"I've had a few hairs that alternated black & white before going grey. If your hair is short you might not see that."
]
} | [] | [] | [
[]
] |
|
16j5uo | what did aaron swartz do wrong and why? | I'm referring to the charges against him. Not his suicide. | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/16j5uo/eli5_what_did_aaron_swartz_do_wrong_and_why/ | {
"a_id": [
"c7winma"
],
"score": [
7
],
"text": [
"He downloaded a bunch of scientific journal articles from MIT, allegedly with the intent to distribute them for free on the Internet."
]
} | [] | [] | [
[]
] |
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