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16723q | Can a fusion reaction occur near the boundary of the event horizon of a black hole with enough material? | I've seen several articles talking about unexpectedly large 'burps' of energy being observed from where some black holes are expected to be. So this got me wondering if, with a large enough cloud of material, it's possible to gravitationally compress the material enough near an event horizon to initiate fusion.
Edit: This is believed to happen on the surface of neutron stars when material builds up on its surface. | askscience | http://www.reddit.com/r/askscience/comments/16723q/can_a_fusion_reaction_occur_near_the_boundary_of/ | {
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"It is probably not possible for sustained fusion to occur near a black hole, but some fusion may occur on a small scale. Matter falling into a black hole can (if the black hole is large enough) attain incredibly high speeds, even significant fractions of the speed of light. If a black hole accumulates a large cloud of matter around it, internal collisions between high-velocity objects can produce short situations with sufficient pressure to achieve fusion. This is not where the 'burps' come from though. The best example we can look at is a [Quasar](_URL_0_), a galaxy-sized cloud of accreting matter that is falling into a supermassive black hole. These incredibly bright objects produce far more energy per time unit than any star and are often likened to a sustained supernova in terms of their energy output. Th only source of energy that could be that plentiful with the sustained output that quasars demonstrate is the release of gravitational energy of infalling matter. This process is not very well understood, but it is far more efficient than nuclear fusion, and is the source of the 'burps' you are talking about. "
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769xsu | which is the best theory on how the world will function in ~100 years (socially, economically etc) and what reasoning supports this/these theories? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/769xsu/eli5_which_is_the_best_theory_on_how_the_world/ | {
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"there is no way to decide which theory is \"best\", and there is no good theory that can be done up in one Reddit post, do i suggest you read some books instead\n\nthe best theory i've read syas that in a hundred years, most countries will have space colonies, which will be used to gather energy and minerals. Far East Asia will be unified as an economic powerhouse, and Europe will have fallen far behind them and the US due to population crunch. Russia will go to war to create a buffer zone in Europe because the using up of fossil fuels in the middle East will make Siberia a big target for other countries. it will be defeated by America, the East Asian alliance, Eastern European alliance, and turkey. the last one will benefit from the fall of geopolitical importance of the middle East after oil runs out, and, with an alliance with Iran, will control most of the middle east and a good chunk of central asia and north africa. it will still be behind Europe industrially and technologically, and will be the major supplier of labour to the then critically undermanned Europe, causing the ethnic ratios to become very skewed. \nAlso, India and Mexico will become superpowers and challenge the US.\n\ni know what i said sounds far fetched, but it's hard summarizing a 300 page book into one comment, and it(the book) does a good job of explaining it, so i suggest you go read it."
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ssfs0 | Question about the magnetic field in relation to the human brain. | This has been bugging me for a while now. What if a human leaves the earth's magnetic field? Would it have an adverse effect with the human brain? Is that even possible? I'm no scientist (Captain obvious) and I'm a bit fuzzy about the moon and it's relation to the EMF. Even if it isn't, look at Buzz Aldrin. | askscience | http://www.reddit.com/r/askscience/comments/ssfs0/question_about_the_magnetic_field_in_relation_to/ | {
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"There's no reason to think it would, because magnetic fields have an incredibly small effect on chemistry (I neglect them all the time in doing theoretical calculations), and the Earth's magnetic field is very weak. It's more surprising, really, that there are birds who've evolved an ability to sense it at all.\n\nAnyway, empirically we also know this isn't the case: We've sent people to the moon, and their brains seemed to work just fine over there. And we routinely stick people's heads in MRI machines to check them out, where the magnetic field is hundreds of thousands of times larger than the earth's field, and not noticed anything. (Nor noticed much chemical effects when using NMR, MRI's chemical cousin) If you think about it, you'll have a stronger field close to an ordinary refrigerator magnet (try it with a compass), and those don't seem to do anything either.\n\nIn short: No, static (unchanging) magnetic fields of that size have no significant impact on your brain or physiology, or almost all chemistry in general. That said, a strong _rapidly changing_ magnetic field can and will screw things up in your brain, since they'll induce currents in your head and screw up the electrical signalling that's going on.\n\n"
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3tr6vv | what goes into making a new font and how hard is it? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/3tr6vv/eli5what_goes_into_making_a_new_font_and_how_hard/ | {
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"Making a new font is a relatively simple process, but can be a lot of work depending on how detailed you want it to be, and how many different letters you want it to span. \n\nIn essence all you do is you open up MS paint, draw your letter, and save it. Then rinse and repeat for every letter in your font. You then just need to convert the file type from a .png or .jpeg to a .ot or .tt. Some software, like Photoshop allows you to save your file directly as a .ot or .tt.\n\nMaking good fonts is harder, you want letters to look the same, and you want your font to have good spacing between letters (kerning). If you're interested in more, check out the [Open Font Library](_URL_0_) and feel free to contribute. Everyone's shitty first attempt is welcome (although it probably won't be downloaded)."
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4m07el | Mouse models for disease? | How do they test diseases, specifically cognitive diseases, in mice, like dementia or Alzheimer's? Or really any disease for that matter. I can't seem to find an answer on Google, however, given my ignorance I may be searching the wrong phrase. Any help would be great. My background is I am certified and work as a paramedic. Thanks. | askscience | https://www.reddit.com/r/askscience/comments/4m07el/mouse_models_for_disease/ | {
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"The answer varies depending on the model. If the gene or mutation that causes the gene is known, the mouse model is usually made by creating that same mutation in the mice. Long QT syndrome is an example of such a disease that has been studied this way. If the genetic cause isn't known, or if the cause isn't genetic in origin (diet, lifestyle, ect) the researchers try their best to simulate the external factors that lead to the disease. After several attempts they usually find the right combination of factors that result in a mouse that presents with the same symptoms as the human disease. This has been done for diabetic studies (in rats more typically than in mice). Additionally for some diseases, like cardiac hypertrophy or modeling heart failure, a surgical intervention can be done to induce the desired disease state. \n\nHow these models are tested depends on how much is known about the disease. Some times we know the gene responsible. From there its usually a matter of figuring out if the mutation results in an overactive protein, and figuring out what drugs will decrease its activity, or if the mutation results in a nonfunctional protein, and figuring out what drugs can restore or circumvent its activity. \n\nFor diseases where we don't know the gene involved, or there are many genes or the problem isn't strictly genetic, we usually screen for drugs that reverse the disease symptoms in our mice models. Researchers have had many years to study mice, so the behavior of healthy happy mice is well known. From there researchers can compare disease model mice to the healthy mice and note any changes or improvements. ",
"Hi /u/plays_in_traffic, \n \nThis is a complex question to answer, especially because the answer differs per disease. \n \nI will use Alzheimers as an example in my explanation since you specifically mention it. Of course I'm going to oversimplify stuff so just respond if you want more in-depth explanations. \n \n \nWhen creating/considering mouse models, there are a few possible ways to look at it. One way is via construct validity. This means that you study the disease, and what causes the disease and the mechanism behind the disease, and you try to mimic this in a mouse model. In Alzheimers this generally means that researchers look at genes that cause Alzheimers in humans. For example, the swedish mutation is a genetic mutation that causes an increase in amyloid and this is linked to Alzheimers. Another genetic mutation that is linked to Alzheimers is presenilin1 (PSEN1). \n--What researchers tend to do is recreate these mutations in mice, and then study the behavior. They will mostly see impairments in learning/retention. The next step is studying possible treatments. This is done by applying a treatment and see if the impairments go away. \n--A big concern/criticism about this model is that you are only looking at the types of Alzheimer's that are caused by these mutations. For example, the swedish mutation is virtually non-existant and in general only about 5 to 10% of Alzheimer's are caused by specific genetic mutations. Another criticism is that these kind of mouse models will never teach you anything new about how the disease is formed. You tell the model how it's supposed to get the disease, so you will never learn something about how Alzheimer is caused in someone who does not follow the construct you worked with. This method of construct validity is most often used because it's really simple and easy to get a APPswe mouse model (for example). \n \n \nAnother method is face validity. This means that the behavior of the mice resemble Alzheimer's. One way to do this is to study a population of rats and do a learning test/memory test - of course multiple tests/observations would be done to account for multiple symptoms. The 5% of the rats that score the lowest are then labelled as resembling Alzheimer's. \n--One good aspect about this method is that you can actually learn something new about how a disease is formed. Just like in humans, the rats Alzheimer-like behavior could be explained by a myriad of reasons and you could study these to learn more about the disease itself. Difficult things with this method are that for most cognitive diseases, it's really hard to recognise it in mice, or worse, it doesn't even really exist in mice. How would you see if a mouse is depressed? How would you see if a mouse has Alzheimers? There are tests designed for this but these are based on human symptoms, so we might just be looking at an entirely different disease that displays the same symptoms. \n \n \nLastly researchers use predictive validity. This often goes together with face or construct validity. This method consists of having a mice that resembles Alzheimers, and then you study whether already proven effective treatment methods are also effective in this model. If these treatment are effective in this model, or produce similar results as in humans, it is said to be a good model. \n--A problem with this is that obviously human treatments might not transfer correctly to an animal or even do something completely different. \n \n \nThere are other ways, and if you want to know specifics, just respond to this. The biggest criticism with mouse models is that barely anyone is creative. We are just creating models based on knowledge we already have, therefore only confirming the knowledge we already have instead of learning groundbreaking new things about a disease.\n\n\nEDIT: \n[[1]](_URL_0_) - Specific mouse models that are being used for Alzheimer's. \n[[2]](_URL_1_) - About what is being looked at when making a mouse model. More about construct/face/predictive validity."
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1lymbl | How realistic was Chiang Kai-shek/the Republic of China invading and retaking Mainland China? | Chiang Kai-shek, shortly before leaving the Mainland and escaping to Taiwan vowed to retake the country. Since the KMT's retreat to Taiwan both sides have had a stand off, even to this day. Of course now the possibility of odds of the Republic of China invading the Mainland are very low for a number of reasons but how about during the Cold War, especially during CKS's rule?
It appears that Chiang Kai-shek really was determined to invade and retake the country but was there really substance to this? Obviously the PRC were concerned but was it just rhetoric or was there a good chance the Republic of China would retake the entire country? Especially during the Great Leap Forward and potentially the Cultural Revolution there were opportunities for the ROC to invade but I'm not sure.
I've tried to find the answer online but so far I've not found anything concrete. Any help on this (which has been on my mind for quite sometime) would be greatly appreciated! | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/1lymbl/how_realistic_was_chiang_kaishekthe_republic_of/ | {
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"Well until someone with perhaps more verifiable sources can comment, I can take a shot at this based on my experiences interviewing villagers in Southwest China and urbanites in Taiwan. In addition, I will try to tie this in with what I learned from both Chinese/Taiwanese professors, and while in the United States undertaking an undergrad in East Asian studies.\n\nThe answer to your question largely depends on what exactly you meant by \"re-taking\" the mainland? Do you mean could the ROC march back into Beijing by sheer military force? Or do you mean could the Guomingdang effectively reinstate their authority on the mainland population?\n\nIf you looked into historical sources on the Yuan and Qing dynasties, you will understand the difficulty in asking the latter. In practically any case where a foreign entity attempted to rule over the Chinese populace, they ultimately it difficult to impose their culture and ideologies on the public, and often ended up becoming absorbed by the Chinese civilization, whom it appeared was greater than the sum of all its borders.\n\nNow obviously Chiang Kai-Shek and the KMT/GMD (depending on what spelling you prefer) were not \"foreigners\", but the fact of the matter was that by the time the Japanese were retreating after World War 2 and the Chinese Civil War was reigniting, the Communist Party has already amassed a huge base of support among the massive agrarian population, which was crucial in gaining ground against the KMT, who were seen as corrupt an apathetic to the plights of those in the countryside.\n\n\nWhat I got out of my time in the countryside of Yunnan and Sichuan Provinces, China, was that even today, the love and adoration for Mao Ze Dong is permeable and strong. To a lot of people, especially the older ones that I spoke to, Mao and the CCP were seen as \"knights in shining armors\", who instituted land reform, agricultural practices, medical care, etc. I of course also spoke to individuals who had lost loved ones during the famine of the Great Leap Forward, and those who had been imprisoned for 18+ years during the Cultural Revolution, who obviously did not share such admiration, but there was still a significant amount of people even today who proudly display pictures of Mao in their homes with no hint of being coerced into doing so (the police are largely non present here).\n\nThe point is, even today there are many who express nostalgia for the \"iron rice bowl\" era and still do hold on to their red books. Even after I spoke to these people, it is still impossible to imagine the fervor some of them held when Mao rolled into Beijing.\n\n\nSo what does this mean for Chiang Kai-Shek? Well, even if he managed to re-invade the mainland, with or without US support, he would find himself facing an extremely hostile and recently empowered population residing in a country spanning the entire length of the continental United States. Even if he and his armed forces were able to successfully defeat the Communists, he would then have to face the greater battle of rebuilding the Republic of China in a country who historically has been notoriously resistant to subjugation.\n\n\nIf you are asking simply in regards to the military capabilities of the ROC, then I'll let someone else much more knowledgeable discuss that; however, from my studies and experience, Chiang Kai-Shek and the KMT would have had an extremely difficult time reinstating the ROC to its original borders. Even during times of crises like the Great Leap Forward, the geopolitical impact of the ROC attempting to invade the mainland and risk another civil war during the broader context of the Cold War would have like made the idea not too palatable to anyone. \n\n\nAgain, sorry about not specific sources. This is focusing primarily on first-hand sources conducted through private interviews rather than vetted historical sources.\n"
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ekmsle | Can we ever know the exact area of a circle if the decimal part of pi is infinite? | Edit: WOW! I'm staggered with the level of response and debate my question has generated! Way more than anything else I have ever put on Reddit. Also, thank you to the anonymous kind stranger for both the coins and the award. That was also unexpected and another first for me.
Just to quickly clarify where my head was with the question, I simply couldn't understand how all the math I'd been taught at school that told me the area of a circle is pi x r^2. I kept thinking that if pi cannot be accurately derived, then how can any formula result that depends on it be accurate either. I just started to think that it would be just a very precise estimate but as a kid I always thought math was an accurate pursuit. Thank you all for an enjoyable debate! | askscience | https://www.reddit.com/r/askscience/comments/ekmsle/can_we_ever_know_the_exact_area_of_a_circle_if/ | {
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"This is a fun discussion. I will add my two cents. \n\nAs many people have stated, mathematically the answer is yes. A circle with radius 4 has an area of of 4\\*pi\\^2. The fact that pi is irrational does not take away from the exactness of this answer. \n\nPhysically speaking I can think of two answers. The case were you have a perfect ruler and the case were you do not. \n\nIf you have a prefer ruler than you must consider if space itself is continuous. The current thinking here is that the smallest region of space that makes sense to think about is the plank length (10\\^-35 m). At distances less than this our current under standing of physics breaks down. We don't know what happens at \"smaller\" distances. Therefore, measuring distance more precisely than this does not make sense even with a perfect ruler. \n\nIf you don't have a perfect ruler we can instead consider the best ruler people have ever made. This is the Laser Interferometer Gravitational-Wave Observatory (LIGO) which can detect changes in distance as small as 10\\^-22 m. It is used to detect gravitational waves, which are small ripples in spacetime. Measuring distances smaller than this is beyond our current engineering capabilities.",
"Yes. If the radius of a circle is *r*, the area enclosed by the circle is πr^(2). \n\nI think you are confused between what it means to know a number exactly and what it means to have a terminating decimal representation of that number. In fact, a lot of undeserved attention is paid to base representations, when they really don't affect any of the most useful and interesting properties of a number, e.g., rationality. How we write or represent numbers doesn't actually affect or change what the number is. It's like how what a chair is is not affected by what you call it, whether it's \"chair\" or \"silla\" or \"Sessel\" or something else.\n\nThe number π is known exactly. It's just ... π. That's it. We can even *define* it as the ratio of a disk's area to its radius-squared.\n\nSince π is irrational, its representation in *any* rational number base must be infinite and non-periodic. So we cannot write down a finite digit representation of π. But there are plenty of *irrational* bases in which π has a finite representation. Trivially, in base-π, the number π has representation \"10\" (but also the infinite, non-periodic representation \"3.011021110020....\")\n\nIn base *b*, there will always be numbers that cannot be uniquely represented (e.g., 0.499... = 0.5 in base-10 and 0.111... = 1 in base-2) and there will always be numbers that have infinite representations (e.g., 0.333... = 1/3 in base 10 and 0.010101... = 1/3 in base-2). That doesn't mean we don't know those number exactly. For instance, the number 1/3 is the unique number *x* such that 3x = 1. That's the definition of 1/3. But if we choose an integer base *b* for which *b* is not divisible by 3, then 1/3 will have an infinite digit representation.\n\n(The only feature about 1/3 that really separates it from π in this context is that 1/3 is rational, but π is not. So in any integer base, 1/3 always has at least one eventually periodic representation.)\n\n---\n\n**edit**: Copy-pasting a response of mine below for more clarity.\n\n > This doesn't \"sidestep\" the question. If you know *r* exactly, then you know πr^(2) exactly. \"How big is that disk with radius 1 meter? Its circumference is 2π meters and its area is π square-meters.\" All of that is exact and, yes, those are the exact numbers in base-10. That has nothing to do with how we represent numbers, and that's really the only reasonable sense in which \"know\" should be interpreted.\n\n > The problem is that many people confuse knowing a number with being able to write it down with finitely many decimal digits (so we don't know 1/3?), or at least being able to write it down with finitely many decimal digits and some periodic pattern (so we don't know sqrt(2)?). Too much attention is paid to base representation and too many properties of a number are conflated with its base representation.\n\n > Let's look at some other ways you might \"know\" a number...\n\n > If you have some other convoluted definition of \"know\", then you have to specify exactly what you mean. If by \"know\" you mean that...\n\n > * ... you can represent the number with a finite digit representation in base-10, then you can't know the number 1/3 but you can know the number 1/4.\n > * ... you can represent the number with a finite digit representation in base-3, then you can't know the number 1/4 but you can know the number 1/3.\n > * ... you can represent the number with an eventually periodic digit representation in base-10, then you can't know the number sqrt(2) but you can know the number 89102/2123901.\n > * ... you can represent the number by constructing a segment of that length with a compass and unmarked ruler, then you can't know the numbers 2^(1/3) and cos(2π/7), but you *can* know numbers 2^(1/4) and cos(2π/85).\n > * ... you can represent the number by constructing a segment of that length with a compass and *markable* ruler, then you can't know the number 2^(1/5), but you *can* know the number 2^(1/6). (Both of these numbers were also unknowable in the previous bullet point.)\n > * ... you can measure such a length exactly, then you can know 0 and precisely one nonzero number of your choosing *but no other number*.\n\n > Note that with any of these definitions (except the last), you can't know any transcendental number like π or *e*. Some transcendental numbers even have base-10 representations with very easily described patterns, although they are not periodic. For instance, the number\n\n > > 0.110001000000000000000001000...\n\n > is transcendental. Under any of the above concepts of \"know\", you don't know this number. But its base-10 representation is actually very easy to describe: \"the digits are all 0, except where this is a 1 in each *N*th place, where *N* is a factorial\". So there is a 1 in places 1, 2, 6, 24, 120, 720, etc.\n\n > You will find that with these other definitions of \"know\", they don't even all agree about what you can \"know\". It's all just so arbitrary, and there's just way too much emphasis on knowledge of the number depending on some physical reality. The implicit definition of \"know\" that I used in my original post is really the only reasonable interpretation of \"know\". Do you even \"know\" the number 1? Why? Mathematically, it's just this thing we define to have certain properties, just as we do with pi. There's really no difference.",
"I would argue Yes, just not in decimal form. All of the infinite decimal places are contained in the singular symbol of Pi, so the equation A=Pi*r^2 is perfectly accurate. \nFor any practical application, ex: car engine parts manufacturing, I would still say yes.... and you can truncate pi to whatever gets you within your desired margin of error.",
"We talking abstract or physical object here?\n\nAbstract - a perfect circle of radius 2, say, has an area of exactly 4pi. That is an exact area, and a perfectly good number. The fact that it's a non repeating decimal doesn't actually matter until you try to make it physical and so have to measure things. \n\nPhysical - any accuracy issues will be more related to instrument accuracy than numerical accuracy. If a perfect circle somehow did exist, the issue would be measuring its radius. That measurement will be done to within some accuracy, then we're back in the situation above: that squared times pi. Similarly for creating one.",
"Well it depends how you write it...\nIf you want to write it in decimals you will always end up with something that you can't exactly write down... But either way you can always just stax with the π in your answer\n\nBecause it's r(square)*π\nIf r is 3 you will have 9π as your solution and that is basically exact because pi is defined...",
"You could say the area is exactly 1 if the radius is 1/sqrt(pi). That's if you want a rational area as the answer, but you'll always have some input or output of the area equation as an irrational number. In this case the input is irrational",
"You can't know the exact area practically because you can only measure the radius so accurately. If knowing the decimal expansion of pi sufficiently accurately was the issue (it never would be) you could measure the radius and circumference and calculate the area as\n\nA = r * circumference / 2\n\nNo pi needed.",
"There are some great in-depth answers about the definition, function, and operations of numbers, but I think some are missing the OP's point a bit. I have what I think is a much easier way to explain it and visualize it. Please let me know if it helped you, or if have any errors or misunderstandings.\n\nWhile pi itself is irrational (decimals don't always like fractions and vice versa) when we think about it in algebraic form, 1 divided by the square root of pi - 1/√π - is a legit fraction, at least to write down and work with for now. Right, why not, so then make that the radius, you then have area of a circle with area defined as π•(1/√π)² = 1.0 exactly.\n\n1 think you're also partly asking \"so then can we know the full infinite digits in the number that would be the radius/diameter/perimeter?\" Not really because you chose to make the area EXACTLY 1. But there are interesting ways to wrote decimals as fractions in infinite formulas. Look for info about Srinivasa Ramanujan. He was self-taught and it's incredible subject matter, contemplating infinity and how to conceive it and work with it. Georg Cantor is another one.\n\nWhen it comes to real life applications, how to take proper measurements, properly recording the measurements, the method of function of the measuring instrument and their tolerances, and significant figures during the math are all important factors that are related to your accuracy.",
"There are 2 answers to your questions really, yes in that we know the area of a circle is exactly πr². The other answer is when using the decimal representation of pi, past a certain point the decimals stop adding very much more accuracy. For example JPL uses 15 decimal places of pi and when you work out the distance for Voyager 1 to earth you will find an inaccurate of something like 1.5in vs a circle with a 12.5 billion mile radius. Practically speaking then you don't really gain very much more by using tens and hundreds of decimal places in terms of accuracy. Past a certain point it stops mattering",
"I can never finish trying to write the decimal expansion of 1/3.\n\nBut 1/3 \\* 3 = 1. Exactly.\n\nDecimal notation is a convenient way we can write down things, but it's not perfect. There are several really really useful numbers that decimal expansion doesn't handle. The numbers aren't weird, but decimal notation can't handle them nicely. Examples: pi, square root of 2, natural logarithm base e.",
"Yes, assuming you define “exact”. \n\nIn science, maths and especially in engineering it is normal to define to how many decimal places any value is expected to be accurate. On engineering drawings this is sometimes in the legend, or sometimes by specifying zeros in the decimals of each value. Once specified, any value on the drawing is expected to accurate to plus or minus half the smallest decimal.\n\nIf a size was given as 10mm, it could be between 9.5mm and 10.5mm. If it was given as 10.0 mm it would be 9.95mm to 10.05 mm. 10.00mm is 9.995mm to 10.005mm. (Someone correct me if I’m out by a decimal, it’s a while since I did this practically😳, but the principle remains sound)",
"A *rational number* is simply a number than can be written as a fraction. For example 3, 1/7, and 57046/9494 are all rational numbers. In decimal, a rational number will either terminate or repeat itself infinitely.\n\nAn *irrational number* cannot be expressed as a fraction, and as a decimal it will go on forever without repeating.\n\nMost numbers (by any reasonable definition of \"most\") are irrational.\n\nFinite addition, subtraction, multiplication, and division (except by zero) of rational numbers will always produce another rational number. Other things such as square roots and infinite sums can produce irrational numbers.\n\nIf a circle has a rational radius, its area must be irrational. Conversely if a circle has a rational area, its radius must be irrational. (A circle may also have both radius *and* area irrational).",
"People here are talking about the rationality of pi. However, it is possible to construct a circle with an exact area to a terminating decimal place. The result is that the radius of the circle will then be irrational.",
"So with 40 digits of pi, we can calculate the area of the universe to the accuracy of a hydrogen Atom, So by the time you go farther than there you're calculating something to the exact to the point where any further detail wouldn't add information.",
"It depends on what you mean.\n\nWhen it comes to mathematics we can define things exactly. \n\nwhen it comes to real-world objects we define things within boundaries called \"significant digits.\" We can call a bolt 1\" long but there is no such thing as a bolt which measures 1.000...(infinity zeroes)\" long. \n\nSo the exact circumference of a circular object in the real world is not an actual thing. The exact circumference of a circle in mathematics is r x 2 x Pi.",
"What do you mean by exact? \n\nThe area of a circle with radius r, is EXACTLY pi\\*r\\^2. \n\nPi is exactly pi, it has a clear definition as the ratio of the circumference and its diameter.\n\nThe decimal part of 1/3 is also infinite, do we not know what \"exactly' 1/3 is?",
"\"Exact\" does not exist, at some point we have approximations, and further down we are at out right probabilities in terms of \"space\" (distance). The universe you observe is different than the universe I observe, we have to agree to accept some error so that we can have a commonly accepted reality. The precision to Plank length is arguably the end of practically measurable reality.\n\nSo yes, in reality we can calculate the area of a circle such that no one can disagree via methods of measurement. Mathematics are intended to abstract reality, just because you can keep the math going, doesn't always mean its useful.\n\nThis concept was a logical struggle since disagreements between Aristotle and Zeno on the divisibility of time and distance, scientific methods struggled right struggling with 17th century concepts, you need to learn to give up and accept some lack of precision, we get concepts like \"infinitesimal\" winch is something but might as well be zero, and hence Calculus is invented.",
"Yes. define a circle with area 1 and its diameter becomes irrational. Also, if you are satisfied with talking in a numerical representation that uses pi as a symbol, then we can represent all areas exactly. it is simply the decimal representation that is so complicated.",
"the only way would be by not knowing the radius exactly, for example if r = sqrt(1/pi) \n\n\nAnd I disagree with the answers claiming that we \"know\" the value of pi: in the spirit of the question we don't, we only know an algorithm for calculating an algebraic number arbitrarily close to pi, but never the actual value of pi itself and we also know how to write down expressions that would evaluate to pi exactly if we had infinite time and memory, so this does not constitute \"knowing\" in the spirit of the question either",
"I see you've already got a whole bunch of really good answers, but I'd still like to add how I prefer to think of these issues. Might not be as mathematical precise as some of the other answers, but I find it a useful tool when thinking about this, and similar \"precision\" issues.\n\nI like to think of this in a kind of backwards fashion. Imagine using \"pi\" as the base unit of a number system, then we get in a similar situation, but instead when we try to represent just about any number that is not pi - with some details depending on exactly how we decide this number system works.\n\nOne (decimal 1) would be pi/pi, which is exactly one. Even though any attempt to \"write\" one (decimal 1) exactly as \"decimals\" in this number system would fail, the number one is still perfectly well defined. It's still the one glass of water, the single sun rising over the horizon, and the radius of a circle with area pi*pi - an area that could be written as \"pi\" in such a base, or more succinctly \"1\" as pi is our base.\n\nIt's really all a matter of perspective, we feel pi as being less real than one, but it's really not. As an abstract concept both one and pi is well defined, but in the real world, neither is. Small fragments of a favourite sweater is left behind whenever it's handled or worn, it will accumulate molecules of odour or dirt. Thus, if we were to somehow *measure* if that sweater is actually one sweater, we couldn't really do it perfectly without relying one some approximation of our abstract intuitive notion of one.\n\nThis would be very similar to how you can't measure area and radius of a real - physical - circle and get the exact value of pi, which is something of the inverse of the question you asked.",
"FYI, knowing Pi to 10 digits after the decimal is accurate enough to get a satellite into orbit of Saturn or Jupiter. The Pioneer and Voyager probe programs reportedly didn’t use more than that. Nowadays we have the computing power to do way more than that with a 10 year old phone. But for almost anything you do outside engineering or aerospace, 3.14159 is probably more than you’ll ever need.",
"You can only know the area as precisely as you know the radius. No measurement is infinitely precise and we know Pi to way more digits than are needed for any practical purposes. 3.14 works fine in most instances."
]
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t5epf | Is there something better than History of the World? (J.M. Roberts, 2007) | _URL_0_
I'm talking strictly of non-textbooks.
EDIT: Added info,
> I've only ever read articles and wikipedia entries (and occasionally their sources). I'm new to books about history, so I'm trying to find some that cover a lot of ground in as few volumes as possible. Although I am looking for general world history books, I can think of a few places that I haven't quite looked at: Africa and the countries of Scandinavia. I suppose one thing I'd be the most interested in is an origin book for European and/or Asian faerie tales, though I don't know how thorough that sort of thing might be... | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/t5epf/is_there_something_better_than_history_of_the/ | {
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"It's probably the best book to start with. If you tell us more specifically, what you are looking for, we may be able to give you better recommendations. For general world history, *A World History* by Clive Ponting is quite good too. It focuses more on the \"East\", while Roberts' focus is the \"West\".",
"You can also read A History of the Modern World by Palmer, Colton and Kramer!"
]
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| [
"http://www.amazon.ca/The-New-Penguin-History-World/dp/0141030429/ref=cm_wl_create-landing"
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[],
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3efx85 | Magnets and Space Travel? | With the Navy unveiling their new rail gun, would we be able to use the same technology to send things (spacecraft, satellites, ect) into space? I feel that by using a rail gun like system it would make it so we could explore farther and get their a lot faster by saving fuel and money. Anyone have any information or thoughts on the topic? | askscience | http://www.reddit.com/r/askscience/comments/3efx85/magnets_and_space_travel/ | {
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"There have been a number of proposals of a similar nature, and they all fall short on three fronts:\n\n1. Cost\n2. Materials Science\n3. Politics\n\nA rail gun large enough to accelerate any machine with a low enough degree of acceleration to avoid destroying the payload would have to be *immense*. We're talking *miles* long. The rail gun being deployed by the Navy is just that: a gun. The projectile will experience extremely large acceleration forces on the way out of the gun. To pull this off with something containing sensitive equipment (like a satellite), a much longer acceleration time would be required.\n\nThe cost of building and operating a gun like this would be astronomical.\n\nThe second problem is with the atmospheric heating of the craft on the way up. If you're moving fast enough to get most of the way to orbit, then you're also moving fast enough to be experiencing some seriously extreme atmospheric heating. Spacecraft returning to earth don't have such a hard time (comparatively) because the atmosphere they're entering is MUCH thinner than the atmosphere near the ground. Moving at 8km/s at or near sea level would almost certainly destroy anything. The materials that could survive this kind of launch without weighing too much simply don't exist.\n\nThe third problem is, with all things, politics. Whenever you completely change the way you do something as expensive and dangerous as spaceflight, you have to convince a large portion of everybody involved in spaceflight that it's a good idea. The risks associated with any radically new technology in this area can be quite high, considering the costs involved. Convincing the people cutting the checks (governments) to invest in anything not proven to work would be an immense political battle.",
"Let's apply Fermi method or order of magnitude calculation. If you're moving at about escape velocity, ~10 km/s, then you have to displace about 1 ton per kilometer of air per 1 m^2 of frontal area, so that would be 10 tons/s/m^2. At these speeds a blunt heat shield is the only option, let's say 1 m^2 frontal area. Change of momentum would be 10000 m/s × 10000 kg = 1e8 kgm/s. Flying ~10 km (isobaric height of atmosphere) would take 1 s, so rate of change of momentum or force would be max. 1e8 N/m^2 i.e Pa, or 1000 atm, higher than in a gun barrel. Over 10000 m, that would mean a work of 1e12 J/m^2, 1 terajoule, over at least a second. Most of it would be spent on the atmosphere, but we're still talking about sitting next to a gigawatt heater. You'd need to evaporate about 5-500 tons of water as a coolant."
]
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2bus38 | Will a light source change direction inside a black hole? | I was wondering how light emission is affected by gravity near the event horizon. Suppose a flashlight is falling into a black hole facing outwards. Since light cannot escape the black hole, and a trajectory of a single photon is smooth, I would assume that as soon as the flashlight crosses the event horizon, its particles can no longer emit light in the direction towards the event horizon. Is this correct? | askscience | http://www.reddit.com/r/askscience/comments/2bus38/will_a_light_source_change_direction_inside_a/ | {
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" > Suppose a flashlight is falling into a black hole facing outwards. Since light cannot escape the black hole, and a trajectory of a single photon is smooth, I would assume that as soon as the flashlight crosses the event horizon, its particles can no longer emit light in the direction towards the event horizon. Is this correct?\n\nYes, that is exactly right! Inside the event horizon, *all* paths that light (or matter) can take point towards the singularity; no path points outward toward the event horizon.\n\nThe three images on the right side of [this Wikipedia article](_URL_0_) do a pretty good job of illustrating this, if you're interested.",
" > I was wondering how light emission is affected by gravity near the event horizon. ... crosses the event horizon\n\nThe path of light is also affected outside of the event horizon. Gravitational lensing: _URL_0_ \n\n"
]
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| []
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[
"http://en.wikipedia.org/wiki/Event_horizon#Event_horizon_of_a_black_hole"
],
[
"http://en.wikipedia.org/wiki/Gravitational_lens"
]
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eu7wxk | why can healthy eyes look in only one direction, i.e. why can’t our eyes look in different directions from each other? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/eu7wxk/eli5_why_can_healthy_eyes_look_in_only_one/ | {
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"Our eyes can look in different directions. When you look at the tip of your nose, your left eye is looking right, and your right eye is looking left.",
"They can be trained to look independently, but our body was evolutionarily selected for the two eyes to work together. It's hard to break the instinct to utilize them in tandem, and there is very little advantage to doing that.",
"Under normal conditions, there's these control centers in your brain that tell your eye muscles to move at the same time. Your brain has to receive the same image from both eyes so that it can paint the world around you. If the left eye is looking to the left and the right eye is looking to the right, then the images don't match up and it makes you feel sick.\n\nLonger, not ELI5:\nLight enters your eyes and the information goes to the optic nerve, optic chiasm, and ultimately to the primary visual cortex in the occipital lobe (back of your head). Information is processed here and the output is sent to the muscles that control the eyes via cranial nerves (CN) 3, 4, and 6. CN 3 controls basically every eye muscle except for the superior oblique (CN 4) and the lateral rectus (CN 6). However, before the information from the primary visual cortex can be transmitted to the eye muscles, it has to go through certain control centers. One of which is the medial longitudinal fasciculus (MLF). The MLF is responsible for conjugate horizontal gaze which means it makes sure that the muscles for looking left and right contract at the same time so that your eyes are moving in sync. It does this by sending information to CN 3 (responsible for medial rectus) and CN 6 (responsible for lateral rectus). There's another area called the rostral interstitial nucleus that is responsible for conjugate vertical gaze, which is for looking up and down.",
"Some species have binocular vision, meaning two eyes pointed the same direction, and this gives them depth perception. You need two images to form a 3D picture. Predators tend to have this so they can target prey accurately.\n\nMeanwhile prey animals frequently have eyes on opposite sides of their head (which cannot physically look at the same object at the same time). For these animals, it’s more important to be able to look all around for danger so they can flee rapidly. Seeing the danger with great precision isn’t that important because the result will still be the same: they’ll just run away as fast as they can.\n\nWhichever system an animal’s eyes are set up for, its brain is also set up for. Brain matter is expensive in terms of maintenance calories and animals tend to have as much as they need and no more. There doesn’t seem to be an animal that got SO much use out of switching between binocular/dual monocular that it was worth the cost of the added brain structures. Either that or it just wasn’t useful enough that environment and natural selection drove any species toward it at all."
]
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3gghmb | how and why is there a standard for cylindrical batteries, and why hasn't it happened for flat batteries? | How awesome would it be if phones used the same shape and size battery.
EDIT: I maybe phrased the question wrong. I'm asking more about how a standard like that comes to be. | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/3gghmb/eli5_how_and_why_is_there_a_standard_for/ | {
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"There are numerous standards for flat batteries. Hearing aides have several standardized sizes, as do watches. \n\nPhone makers/companies also tend to have standardized sizes between specific brands or range of brands. They want you to be somewhat limited in options though so that you have to buy replacements from them. "
]
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4255ib | Common cloth materials in medieval Europe? | What're the common cloth materials for ordinary folks before cotton was introduced into Europe from India? Linen and wool were produced, but they must be quite expensive. | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/4255ib/common_cloth_materials_in_medieval_europe/ | {
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"They weren't that expensive because they were home grown. Anyone could put in a patch of flax among the other crops. Women could pull it (one does not cut it and shorten the fibres), though men could help. After that it was a woman's job to rett the flax in the stream to rot off the outer coating and pith. Then the fibres were hackled or combed out to remove the bits not wanted. Repeated hackling produced short fibres broken off, called tow. Tow was used like cotton balls or waste paper for wiping up or stopping wounds. Everyone used tow, because every woman spun linen. Once the flax had been bleached on the grass, it was put up in stricks, which were a bundle to be arranged on the distaff to draw down smoothly into thread.\n\nTaxes were often paid in thread. Single women contributed to a household by extra spinning, so the traditional term for them was \"spinster.\" Extra thread could be sold for cash.\n\nWomen rarely wove at home. That was a job for the weaver's guild, who might trade finished cloth for thread. It was a sign of wealth to have one of the gigantic timber-built looms when they only wove a narrow tabby linen for underclothes (body linen).\n\nWool was a little more specialist. A fine lady would spin flax, but only a peasant would spin greasy wool. I'll bet her hands loved the lanolin. Fleeces were sheared from sheep and lambs before spring so they were spared the summer heat. Qualities of wool were separated out of the different parts of the fleece. These would be carded until the fibres all ran straight and the tangles were out. Then the carding combs would be cleared a clever way to roll the wool into a roving. Wool can be spun without a distaff. Wool can be combed before carding to produce worsted. Again, wool thread was a valued commodity and one of the few ways to get cash.\n\nBut all of these were produced by the peasant class. They still stretched the life of everything, including cutting down clothes so the unworn parts clothed the children."
]
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3ejlaa | if it is thought that dreams only last for fractions of a second at a time and it is our brains that interpret them as longer, what is happening when we talk in our sleep? | I know a lot of our knowledge of dreams is based on theory, would just like an explanation for why my girlfriend never shuts up at night | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/3ejlaa/eli5_if_it_is_thought_that_dreams_only_last_for/ | {
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"text": [
"Good question! Where did you get that information, that dreams only last for fractions of a second? If your girlfriend talks in her dream and in real life simultaneously then that becomes impossible - you're right! And if it is impossible then the conclusion must be: it isn't true.\n\n\nDreams vary in lenght, the further you are into the night the longer the dreams get. Some are very short, you're right about that, but they have been observed to last over 20 minutes in real time"
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1drq25 | What's the best way to use the Bible, when appropriate, as a Primary Source? | When using the Bible as a Primary source, do you use any of the modern popular translations, or do you try to get a direct translation of the transcripts that are most widely accepted as valid? Are there specific translations of the various books that are more widely viewed as acceptable by the academic and, particularly, the historic community or is it more that everyone finds what works for them and sticks with that? Or, is the preferred method to learn the Biblical languages and do your own translations? | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/1drq25/whats_the_best_way_to_use_the_bible_when/ | {
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"I think a lot of it depends on the level of scholarship.\n\nI know that many scholars use the New Revised Standard Edition when a simple verse quotation is required. It was created in 1989 to be good for devotional use as well as scholarly use.\n\nLearning the biblical languages and using ancient copies is done, but this is at a fairly advanced level of historical inquiry or textual criticism.",
"I translate myself, footnoting possible alternate readings. Mostly because I like doing that, and because I can and it makes me look smart. But more importantly, when there's important divergence in understanding or something important with the wording, it's much easier to discuss if you're translating it yourself. You can see through a lot of BS that way.\n\nGenerally, the best Christian scholarly translation is the NSRV, and the best Jewish one is the nJPS. When writing about Jewish stuff, nJPS is usually the standard in academic contexts. But for any discussion of how the bible was seen historically in religious contexts, academic sources don't have much choice but to discuss the Hebrew (or Aramaic, if you're in one of those small sections)."
]
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28ido3 | When and how did the concept of political veto arise? | How did the notion of political veto come to be, and by what rights or criteria did the nation/state/individual come to such power? | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/28ido3/when_and_how_did_the_concept_of_political_veto/ | {
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"text": [
"The romans created it.\nVeto means \"I forbade\" in latin and the right of veto was the privilege of the tribunes of the plebs. When one of them stood up to say \"Veto\" it blocked the decision.\nIronically what was originally a tool to protect the plebeian against patrician abuses of the beginnings of the republic became at the end of it one of the base of the imperial power as Augustus received power over the \"imperial provinces\" and the tibunita potestas, the power of the tribune (of the plebs) enabling him, the patrician to veto any law he would not like."
]
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267l4a | what would happen to a person if they were to undergo a brain transplant? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/267l4a/eli5_what_would_happen_to_a_person_if_they_were/ | {
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"text": [
"This would technically be a body transplant, you are your brain."
]
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36by1z | why is snowden seen as such a hero? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/36by1z/eli5_why_is_snowden_seen_as_such_a_hero/ | {
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"Because of the breadth of what his leaks revealed.\n\nWe spy on our allies. We spy on our own private citizens. We spy on neutral third parties that are no threat at all like fucking Brazil. We spy on everything, *because we* can, *and because noone will stop us*. \n\nAlso, the [NSA doesn't really do much to not appear cartoonishly evil](_URL_0_). ",
"...\n \nDid you not understand the things he revealed to us? Or did you not believe them? He revealed, with undeniable proof, some terrifying things about the government. He did so with great personal cost (he can never live a normal life again) so that other would know that we're being lied to, and so that we could know what's really going on. That's why he's a hero.",
"Our government is supposed to be our servant and not our master. Snowden revealed our servant has been secretly spying on everything we do, violating our fundamental human right to a private life. Those people who have access to the information have become even more powerful because they can use it to suppress opposition. If you become an annoyance to them you will soon find embarrassing aspects of your private life leaked to the tabloids. Knowledge is power."
]
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"https://www.techdirt.com/articles/20131205/15585425475/us-spy-satellite-logo-not-all-subtle-octopus-enveloping-earth.shtml"
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|
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eypcfa | What happens to an island formed in a hotspot when in a subduction zone? | Fx. In the case of Hawaii. Imagine hawaii moving all the way to the coast of japan over the span of a long time. What would happen with the island when the plate dives under the plate of japan. Will it just sink with it? Will it be shaved off? | askscience | https://www.reddit.com/r/askscience/comments/eypcfa/what_happens_to_an_island_formed_in_a_hotspot/ | {
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"This depends a bit on the proximity of the hotspot to the subduction zone and the nature of the material that makes up the island / feature. In a general sense, as plate motion translates an oceanic island away from the hotspot, the island will start to 'sink' as the area around the oceanic island cools (cooler crust = denser crust = lower elevation crust). This coupled with erosion of the island before it sinks below the surface and the potential for continued mass wasting after it is below the surface of the ocean, means that generally the prominence of former oceanic islands diminishes with distance from the hotspot. This is illustrated in [diagrams like these](_URL_2_) and can be seen in the real world in trails of seamounts behind hotspot related oceanic islands, like the [Hawaiian-Emperor seamount chain](_URL_4_).\n\nThe relative volume/prominence of the feature when it reaches the subduction zone will determine what exactly happens (and hence why distance between the subduction zone and the hotspot matters). Small seamounts and similar features are successfully subducted all the time, though their subduction may cause deformation of the [accretionary prism](_URL_6_) or overriding plate, e.g. [Dominguez et al, 1998](_URL_3_). If the seamount is larger or still a true oceanic island (or something really big, like an [oceanic plateau](_URL_5_)), then it is more likely that it will, at least in part, [accrete](_URL_0_) to the margin. An example of this would be the [Ontong-Java plateau](_URL_1_), an oceanic plateau which is related to the eruption of a plume head (i.e. the beginning of a hotspot) and that is now being subducted. Portions of the plateau material have been scraped off and are thrust up along the subduction margin while other portions have continued to be subducted."
]
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| []
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"https://en.wikipedia.org/wiki/Accretion_%28geology%29",
"https://en.wikipedia.org/wiki/Ontong_Java_Plateau",
"https://geography.name/wp-content/uploads/2016/08/56799-640x345.jpg",
"https://www.sciencedirect.com/science/article/pii/S0040195198000869",
"https://en.wikipedia.org/wiki/Hawaiian%E2%80%93Emperor_seamount_chain",
"https://en.wikipedia.org/wiki/Oceanic_plateau",
"https://en.wikipedia.org/wiki/Accretionary_wedge"
]
]
|
|
40wvev | A century ago, in the aftermath of WWI and with the dissolution of the Ottoman Empire, the world had to deal with millions of refugees and mass migration. How did the receiving countries deal with this influx? | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/40wvev/a_century_ago_in_the_aftermath_of_wwi_and_with/ | {
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"Not an answer, but a follow-up question ; How and why did the Ottoman empire dissolute and disappear?",
"This depends on a case-by-case basis. I am unfortunately unable to give you a fully-fledged answer in general, but would be happy to explain what happened in the Netherlands during the War and the immediate post-war period with (predominantly Belgian) refugees, if you are interested. I could also be of some help in illuminating the emergence of the closed-border and passport systems in the immediate pre-war era, again if you are interested in the context. ",
"I would be really interested in that SickHobbit, if you have time. "
]
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62u9lp | what are those fake puddles of water that appear on the road and disappear as i drive closer? | [deleted] | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/62u9lp/eli5_what_are_those_fake_puddles_of_water_that/ | {
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"text": [
"Mirage. Optical illusion that form when light coming form critical angle bounce(reflection) off instead of refraction. As you approach closer you are no longer in the path of that bounced light, so it disappear"
]
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| []
| [
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1kk02m | why do so many think robert johnson is the greatest bluesman? | According to Elijah Wald's book, Johnson wasn't influential until whites (esp. Brits) picked him up in the early 60's. I've listened and listened and he's really good, but I think others of that era are as good or better. Help me out, please. | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1kk02m/eli5_why_do_so_many_think_robert_johnson_is_the/ | {
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"Everything I know about Robert Johnson I learned from the movie Crossroads, but apparently he invented The Blues, or at least wrote all the early classic Blues songs. He was able to do this because he sold his soul to the Devil. "
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1fsv2s | Do humans make bodily or vocal noises above or below the human hearing (20Hz to 20,000Hz) threshold? | askscience | http://www.reddit.com/r/askscience/comments/1fsv2s/do_humans_make_bodily_or_vocal_noises_above_or/ | {
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"Anything that causes a vibration causes a sound, because that's what sound is. While it may not be audible, pretty much any movement your body makes technically makes a sound.\n\nWaving your hand frantically may cause vibration of a few Hertz, for example, even though it's probably very quiet too. Of course, that's just an example you could easily mimic on purpose.\n\nShort answer is yes.",
"Yes, but it's not significant.\n\n Sibalants like fff and ssss have peaks around 5-8K, and some noise around 10ish. The noise up there is what adds airiness to vocals, and it is necessary for normal sounding speech-compare real life voices to telephone or voip. Those kill all the high frequencies and you lose a lot of definition.\n\nThere might be some content up there, but natural noise is not evenly distributed across the spectrum, it's filtered, so there is going to be on the order of 1-2 percent of the energy(30db+ reduction) up there versus at the main sibilant peak.\n\nIf you killed the ultrasonics, you wouldn't notice a difference even if you could hear it. Lower noise would totally mask it. "
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4skykx | What happened to German police personnel after the Germans surrendered in WW2? | What happened to the members of the Ordnungspolizei after the German surrendered? Were they interned? What happened to higher ranking officers? Especially, members of the schutzpolizei, fire brigades, and the gendarmerie. | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/4skykx/what_happened_to_german_police_personnel_after/ | {
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"This is an interesting one. \n\nThe Order Police and the Krippo generally continued as normal, as did most of the judiciary.\n\n\nThe Gestapo was brought in front of the Nuremberg trails where it was decided the it was a criminal organisation and that all officers and administrators were collectively responsible. However, it didn't apply to those who left before 1st September 1939, thus ruling it was only after this date that it became a criminal organisation and this ruled out any officer facing punishment for their actions before then.\n\nVery few rank and file officers were brought to trial and most of those that did served less than three years detention. The Law for the Liberation from National Socialism and Militarism (5th March 1946) allowed individuals, including Gestapo officers, the chance of exoneration by producing evidence and witnesses. Most of the West Germans who applied were exonerated (issued a 'Persil Certificate' - a pun on the washing powder that offered whiter-than-white results) due to those overseeing the process being over worked and under staffed. \n\nIn the East, the Russians were just as 'thorougher' in investigating the past of those involved in the Nazi regime, however, this meant detention. \n\n\nTheir are a number of things we must understand. Firstly, rank and file Gestapo officers were forcibly transferred from the police detective branch and very very few were members of the Nazi party before 1937. It was the senior managers that were ardent career Nazis with no police experience. Secondly, by the 1950s there was a distinct lack of enthusiasm among the West German political establishment to bring Nazis to judgement. Thirdly, the people who the Gestapo targeted were dead by the end of the war and unable to provide witness to the prosecution. Finally, by the late 1940s, the western allies were more concerned with the Soviet Union than the Nazis. Routing out every Nazi, be them part of the civil service or civilians was not only time consuming but removing the low level civil service would make reconstruction and governance more difficult. "
]
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8j3h02 | How and when did the Star and Crescent become a symbol of Islam? What exactly does it represent? | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/8j3h02/how_and_when_did_the_star_and_crescent_become_a/ | {
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"This is primarily trying to answer another question, but it touches on the question you’re curious about:\n\n * [Why didn't the Turkish Republic change its flag?](_URL_0_)\n\nI’m afraid, though, that I come at this as someone who’s interested in the Early Turkish Republican era/the Late (19th century) Ottoman Empire, so I don’t know much more about this early/middle Ottoman question than I listed in that answer. (Edit: this particularly doesn’t cover at all when the star and crescent became a *global* symbol—it obviously appears on flags outside the former Ottoman Empire and outside the context of Pan-Turkism on, for instance, the flags of Pakistan, Malaysia, and Mauritania.)\n\n/u/Chamboz and /u/CptBuck might have more to add. ",
"I did a search of\n\n!g site:_URL_0_\n\nand found:\n\n1. [https://www._URL_0_/comments/5rm5ap/why\\_did\\_the\\_crescent\\_and\\_star\\_become\\_symbol\\_of/](https://www._URL_0_/comments/5rm5ap/why_did_the_crescent_and_star_become_symbol_of/)\n2. [https://www._URL_0_/comments/24d72l/why\\_is\\_the\\_star\\_and\\_crescent\\_considered\\_the/](https://www._URL_0_/comments/24d72l/why_is_the_star_and_crescent_considered_the/)\n\nHope that gives a couple good answers!"
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2clfqx | how come the human race still has "ugly" people if nobody wants to reproduce with them? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2clfqx/eli5_how_come_the_human_race_still_has_ugly/ | {
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"People still do.\n\nEdit: also Luck, two \"perfect\" parents wont always have a \"perfect\" child. ",
"Two very attractive people can still make an ugly baby. And likewise, two ugly people can create a very attractive baby. It all just depends on how the genes interact."
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1scq28 | how did amazon gain enough popularity to support it's massive infrastructure costs? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1scq28/eli5_how_did_amazon_gain_enough_popularity_to/ | {
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"It was one of the first dot coms, back when online shopping wasn't a thing yet.\n\nThey also started niche with just books - an industry which (at that time) had lousy overpriced competition and was impossible for brick and mortar stores to compare on inventory / price. Great place to start.\n\nThen after they became the niche book go-to, they moved to music and movies which had the same basic problem before digitalization.\n\nThen they expanded to more types of merchandise. And so on."
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3yedwh | How long does it take for a large, non-spherical object in space to become spherical? | Let's say an object with about the same mass as say, the Earth, but in the shape of a cube. I assume it would turn into a sphere, but on what timescale? | askscience | https://www.reddit.com/r/askscience/comments/3yedwh/how_long_does_it_take_for_a_large_nonspherical/ | {
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"Assuming the cube is made from the same material that Earth is made of, it would probably not take very long to become spherical. The corners of the cube would in effect be mountains that are many hundreds of km tall, which would collapse due to gravity. \n"
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1kqfek | Why doesn't China have a large muslim population but southeast Asia does even though China is closer to the middle east? | Countries like India, Pakistan, Bangladesh, Indonesia, Malaysia have large muslim population but China doesn't. What led to this? | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/1kqfek/why_doesnt_china_have_a_large_muslim_population/ | {
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"Actually early in China's history it had a larger Islamic population. Several revolutions happened centered around its Islamic population. Infact the famous explore Zheng He, was actually Muslim (it was one of the reasons he was selected actually to ease relations with Arabian leaders, meeting a member of your own religion always makes thing easier).\n\nThat being said Islam in China has historically gotten the short end of the stick. While most Chinese dynasties had little problem with Muslims, who often ended up getting very wealthy off of trade. The mongols harshly apposed several Islamic practices (namely a few festivals and meat perpetration).\n\nThe real 'modern' decline of Islam in china occurred around the rise of Communism. The Red Guard would burn and deface mosques, as well as burn copies of the Quran. Muslims were painted as holding \"Anti-socialist\" views, as well as \"clinging to old superstitions.\" This was true for most religions, not just Islam.\n\nCurrently Islam is on the rise in China, and accounts for about 1-2% of its total population.",
"China does have a thriving Muslim population, though they are in several different groups.\n\nPerhaps the most notable are the 维吾尔族 Uyghurs (pronounced like \"Wee-ger\") in the 新疆维吾尔族自治区, or the Xinjiang Uyghur Autonomous Region (a region some Uyghurs often refer to as Eastern Turkestan). In this region, the largest province in China, Uyghurs are the majority population, accounting for ABOUT fifty percent of the province's ~22 million people. They are a Turkic people, and are often characterized by their devotion to Islam. In general they bare little resemblance to East Asian peoples. Peter Hessler, an American travel writer, said that when he visited China in the 90's many Han Chinese 汉族 (the dominant ethnic group in China that we simply refer to as \"Chinese,\" though incorrectly) assumed he was Uyghyr upon first meeting him. Many Muslims of the Kazakh minority 哈萨克族 are also to be found in Xinjiang. \n\nAnother notable groups of Muslims in China are the Hui (pronounced like \"Hway\") people 回族. The Hui have been present in China since the Tang Dynasty, and are widespread. Major population centers include Gansu 甘肃, Yunnan 云南, Xinjiang 新疆, and other Western provinces. Though ethnically distinct, a westerner might look at a Hui person and think they look very \"Chinese\" as opposed to the Uyghurs who certainly do not. Famous Hui Muslims include the famous explorer from the Ming Dynasty, Zheng He 郑和.\n\nEdit: Just an anecdote. I live in Beijing, and I'm surrounded by Hui Muslims. Where I live, Chongwenmen 崇文门 in Dongcheng District 东城区, they are an everyday sight. There is a beautiful Hui Mosque here, and even a Hui Primary school.\n\nEdit 2: Some numbers. China is home to over 8 million Ughurs, 10 millions Hui Muslims, 1.5 million Kazakhs, and a variety of other Muslim peoples such as Tajiks, Uzbecks, Kyrgyz, etc.",
"As /u/kevink123 mentions, there are in fact quite a few Muslims living in China, but I would add that there are perhaps *fewer* than there would be if it hadn't been for Genghis Khan.\n\nIn a nutshell, during the height of Muslim power in Central Asia, the Mongols rolled through, razed many cities, and slaughtered millions of Muslims.\n\nThere's also a geographical factor. It would be easier for Islam and Islamic populations to spread along the sea trade routes of the Indian ocean than it would be for them to spread through Central Asia and Western China (despite the Silk Road).\n\nIt's also worth mentioning that the autonomous region of XinJiang (China's largest province) now has a population that is roughly 50-50 in terms of Muslims versus non-Muslims, but prior to Communist rule, the region was almost entirely Muslim.\n\nThe [Great Mosque of Xian](_URL_0_) is worth a mention here because it's the oldest existing mosque in China (742 C.E.) and it's notable for being in central, rather than western, China. It's also intersesting from an architectural perspective as it incorporates Buddhist and Daoist elements of design, but without all the iconography that would come with it.\n\nAnother interesting thing that the Xian mosque illustrates is the traditional tolerance towards Muslims in China. There are Daoist, Buddhist, and (former) Confucian temples all within two blocks. Religious pluralism in old China is really quite astounding by European standards. Prior to the 20th century, there is not a single recorded case of serious religious conflict with Muslims in China.",
"Along with what kevink mentioned, I want to note that Islam spread rapidly during the rule of the Abbasid Caliphate (moving the capital from Damascus to Baghdad), as trade grew exponentially in the Indian Ocean. Eventually dominating the whole trade in the ocean, their influence of Islam became extremely prevalent in the coastal areas of trade (Southeast Asia, East Africa, India). ",
"I'd like to piggyback onto this. When and how did these migrations take place, and what were the Chinese rulers' views towards Muslims?"
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2yk5dl | How and when did pepperoni become the default topping for pizza in the U.S.? | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/2yk5dl/how_and_when_did_pepperoni_become_the_default/ | {
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"We've had to remove a number of posts with people sharing what they like on their pizza instead of pepperoni and/or challenging the OP's assumption. Please, if you want to discuss your favorite pizza, that is for another subreddit.\n\nAs for the fact that Pepperoni is the default topic, \"default\" is up for debate, I agree, but I think we can all agree that \"most popular\" is not a very contentious observation, and supported by [polling on the matter.](_URL_0_) So I would ask that further discussion be focused on pepperoni's popularity in the American pizza business, and not on what *you* like on your pie. Thank you!",
"(Had to look at my physical books). According to *The Oxford Companion to American Food and Drink* and January 1985 issue of Gourmet Magazine, pepperoni is an Americanized version of Italian salami. In the early 1900's Italian immigrants brought salami to the US, but traditional salami is a seasonal product that required carefully controlled climate and other conditions and it was difficult to replicate the same process in an urban environment that the immigrants had settled in. Armour meat company developed the technology to control climate and automated the process so they could be produced year round. The first reference to pepperoni in print is from 1919. The American pepperoni uses lactic acid culture and greatly reduced curing time. As a result it became the most available Italian-style cured meat in the US (particularly when pizza became popular in the US in the 50's) before more authentic Italian-style cured meat appeared. In addition due to its shortened curing time the flavor can be improved by heating prior to consuming (usually salami is eaten cold). ",
"Hopefully I do this correctly, I'm a long-time reader but don't often post. I wrote an essay about immigration and the influx of influx of food culture a few years ago in my M.A. program. I'll provide some excerpts and some commentary seeing that there are no useful threads posted yet:\n\nMany will argue that interest in southern/eastern European food did not begin until after our soldiers returned from WWII. There are some arguments, however, that the assimilation of ethnic foods began much earlier. A book entitled, The Grocer's Encyclopedia, published in New York in 1911 provides, a detailed look at the demand for products during the time period. It was essentially publish as a guide for large, commercial markets to understand the differences between different ethnicities and their food. The volume, in addition to containing Jewish Dietary Laws contains list of more than 500 of the most popular food words and concepts translated into German, French, Swedish, and Italian. \n\nAround this time there are also a few other cookbooks that begin to get translated into English for the first time. One volume of particular interest was a compilation entitled With A Saucepan Over The Sea; Quaint And Delicious Recipes From The Kitchens Of Foreign Countries. This volume provided signature recipes from almost every country in Europe and even singled out different ethnic groups by providing Jewish recipes from both Poland and Germany. This demonstrates both the diversity of ethnic groups and also the interest in redefining American food culture with an international palette.\n\nThe increase in the availability of ethnic street food provides some additional evidence that eastern/southern European food was becoming more popular. During the \"gilded\" and \"progressive\" era a large percentage of immigrants were engaged in street vending. New York City during the time period actually made special laws to allow street vending to occur. With the large amount of eastern/southern Europeans engaged in the food market, they had a large impact in the types of food available on the street for regular consumption. (Bhat, R.V. (Editor). Street Foods (Vol. 86, Wrund). Basel, Switzerland: Karger Publishers, 2000. p 27.)\n\nThat being said, pepperoni pizza is an excellent example of a sociological theory referred to as (I believe) the diffusion and reformulation of culture. Just like McDonalds in India has more vegetarian options as they have reformulated the diffusion of fast food culture to meld with their own. Pizza was reformulated to meld with existing American culture. \"Americanization\" was already taking place during this time for immigrants. This americanization movement also extended to food and diet. \"As the waves of immigrants from Europe and elsewhere poured into the great cities of America at the end of the 19th century, earnest American social workers, medical personal, home economists, educators and others became increasingly concerned with the newcomers' diets and health. Numerous studies were undertaken to learn about the immigrant's foodways, mostly in an attempt to change them.\" (Feeding America Project,Michigan State University, Anne-Marie Rachman, Digital & Multimedia Center, Michigan State University Libraries). Immigrants were actively encourage to change their dietary habits to \"healthier,\" American options. \n\nI would assume that pepperoni was one viable option for the reformulation of pizza culture to the U.S. Dried meats were utilized in both the U.S. and Europe. Pepperoni has a relatively long shelf-life and can be used on pizza in the winter when other toppings may not have been available. \n\nI went off subject for a little bit but that's the best answer that I can come up with. In simple terms, pepperoni was a culturally acceptable topping where American's could eat it and feel like they're exploring \"foreign\" food without getting too far off the beaten path. \n"
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8rubkk | One of the main requirements of Islam is prayer, and one of the prayers is at dawn. How did people in the time of the prophet Muhammad wake up for prayer on time, considering there were no alarms at all? | [deleted] | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/8rubkk/one_of_the_main_requirements_of_islam_is_prayer/ | {
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"There are basically two answers. One is that, at least according to the Hadith, the call to prayer already existed and would have been called out for the dawn prayer. The second answer is that pre-modern sleep practices were very different than our modern concept of one, approximately eight hour long period of uninterrupted sleep. Pre-moderns, including Muhammad, would more frequently have had a \"first sleep\", followed by a period of awakeness, followed by a \"second sleep.\" This is also referenced in the hadith: _URL_0_\n\nSeparately, in lieu of alarm clocks, there were plenty of animals that make noise at dawn: _URL_1_"
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14ftp7 | how do disinfectants work? | How do disinfectants, like hand sanitizers work? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/14ftp7/how_do_disinfectants_work/ | {
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"They contain an agent which kills bacteria. In the case of hand-sanitizers, the ingredient is alcohol - specifically, usually, ethanol or isopropanal (there's others too, though). When rubbed onto skin (or surfaces, in the case of other disinfectants) the bacteria are killed."
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21w5iz | how did glow in the dark happen? and where did it get its source of energy to glow in the dark? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/21w5iz/eli5_how_did_glow_in_the_dark_happen_and_where/ | {
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"Around 1669, there was a German alchemist named Hennig Brand. He was in search of gold, and thought that it came from within man. What color is gold? It's a shade of yellow. What else is yellow that everyone is familiar with? Urine. So off went Hennig on a quest to extract gold from pee. He boiled down 5,500 liters of the stuff, and what was left over was a bunch of phosphorus. Phosphorus, for those who don't know, has a tendency to take in light, and hold it for a while, which makes it glow. This is why Hennig named it phosphorus, for the greek \"light-bearer\".\nSo glow in the dark resulted from a scientific fluke. The dude was trying to make gold in an early stab at chemistry.",
"To add to redfoot's answer. If your super lucky, your glow in the dark stuff is not made of phosphors that are energised with light radiation but with decomposing uranium. Before we realised how dangerous that stuff was it got stuck in a lot of things. Watches and kids toys from the 40-60's, if they glow, can contain uranium"
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160zuf | Theoretically, how far "back in time" could we go and still be able to have a conversation with local inhabitants? | Just how much do we know about these ancient languages and dialects? Would we still be able to understand them today? English and other languages too =D | askscience | http://www.reddit.com/r/askscience/comments/160zuf/theoretically_how_far_back_in_time_could_we_go/ | {
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"Warning: This is not my area of expertise at all, but since there have been no replies after half an hour, I'll give it a go.\n\nFirst of all, it depends greatly on what language you'd like to speak in, as you acknowledged in your post. It also depends on who you'd like to speak to - peasants? kings? But the general answer for English is somewhere around the 12th-14th centuries. This is a bit of text from the mid-1100s: \"He chæs himm sone kinnessmenn all swillke summ he wollde and whær he wollde borenn ben he chæs all att hiss wille.\" This is mostly intelligible - it means \"He chose some kinsmen as he liked, and where he would be born, he chose all at his will.\" But they were also using a number of Germanic words that we don't use anymore, and you may have had some trouble understanding a great deal. By the time of Chaucer in the late 1300s - well, you can read Canterbury Tales without any special training, so there you go.\n\nIf you speak Italian, you might be able to go back significantly further. Italian was fractured into many regional dialects until the publication of the Divine Comedy in the 14th century. However, certain regional dialects were more like modern Italian than others, and in those regions you could go back further. The first documented words in Italian date from the mid 10th century; however, spoken Italian dates back much further - in 722, when Pope Gregory II, raised in Rome, met St. Boniface, who had studied classical Latin, Boniface said that he found Gregory IIs Latin very difficult to understand, indicating that the language of the Italian peninsula had already begun to evolve away from vulgar Latin.\n",
"This might be a good question for /r/linguistics. Also, I'm not an expert on this so feel free to take this with a grain of salt.\n\nFor English, the Great Vowel Shift renders spoken Middle English largely unintelligible. This change is thought to have begun in the 1300's and be completed around 1700. Modern English (being attested to the 1500's) falls in this range. I'd conjecture that we today would most likely be able to converse with at least the educated around Shakespeare's time, albeit with some difficultly due to differences in vocabulary and pronunciation. Any earlier gets fuzzy, but as language change is rarely abrupt it could be possible. Middle English is largely unintelligible to people today. Sorry for the conjecturing, but we don't really have access to spoken forms of language in older files (excluding pronunciation gleaned from written texts).\n\nI'm less versed in other languages, but do know that languages change constantly and change differently compared to other even related languages. Some are more conservative than others. Kevin Stroud's History of English podcast claims that roughly it takes 1000 years for a language to diverge from a parent language into a mutually unintelligible daughter language. I would use that number as a basis, but it probably isn't true for every language.",
"You should try posting in r/linguistics. They have a few people who could answer pretty well!",
"That will be different for every region.\nI can answer for my native language, Modern Greek. \nThe classical sound system collapsed around 1st century CE, and it started resembling the modern one around the 4th century CE. Grammar and vocabulary undergone transformations that will lead eventually to modern Greek, so a fluent and somehow linguistically-aware speaker of Modern Greek could understand spoken [medieval Greek](_URL_0_) mostly of the late period of the Middle Ages. As a matter of fact, religious texts written in then-modern Koiné Greek are way, WAY more accessible to Modern Greek speakers, than classical texts (Plato etc), and Homeric texts are completely inaccessible without dedication and years of study."
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2movzc | why are ceiling's spackled or whatever it's called. why aren't they just flat like walls? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2movzc/eli5why_are_ceilings_spackled_or_whatever_its/ | {
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"It's sound damping. Flat surfaces echo more than dimpled ones. ",
"Spackling is the use of spackle to fill holes and cracks. I assume you mean that textured finish on some ceilings. If so, that's just a design choice and doesn't have any practical reason.",
"I work in new home construction in a mid-Atlantic market. We do smooth ceilings (you are describing textured). In my market textured is about 50% of the multifamily housing market and about 0% of the single family market. From my perspective you do this more to hide imperfections in drywall seams than as a sound dampening device. In multifamily it also hides wear and tear where a tenant my cause dents moving in/out of a unit.",
"I always suspected it was to hide a shitty mudding job. ",
"I just recently bought a house and that was one of the first things I did. Scrape all that popcorn crap off the ceilings and make them flat. After checking for asbestos, of course.",
"Major home builders texture walls and ceilings because the texture hides the crappy job their laborers do. These home builders spend as little money as possible on labor (undocumented and barely legal migrant workers compose a significant amount of their workforce, especially in the southwest) and as such, they get what they pay for. Walls aren't flat or plumb, ceilings are not even close to level, and corners are almost never true. As such, they coat every surface possible with texture, which makes it more difficult for eyes to pick up on the imperfections.\n\nSource: A friend of mine oversaw regional construction related business for a major homebuilder in the southwest until the housing bust.",
"It's mostly about labor costs and appearance. \n\nIt's not all that easy from a modern craftsmanship standpoint to get flat, smooth ceilings that hide the seams in the drywall. \n\nIn old houses that haven't been renovated you'll often see smooth ceilings. As I understand it, this is because they were plaster and the plasterers had the skill to make it look flat and smooth."
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34xm8m | Are there any current historical debates/uncertainties between historians in regards to Spartacus? | I'm required to write an essay on Spartacus and I just can't find anything to debate/argue about. :/
A response will be most welcoming :) | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/34xm8m/are_there_any_current_historical/ | {
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"The main uncertainty about Spartacus is his ethnicity. He is called a Thracian, but Thracian is both an ethnicity and a style of combat in gladiatorial games. Gladiators were organised by their combat style, and by that point in Roman history gladiators were no longer limited to just their cultural combat style, especially if the slave was not one of the traditional enemies of Rome. So while it is possible that Spartacus was from Thrace, it is equally possible that he was from pretty much anywhere else, and simply trained in Thracian-style combat as a gladiator."
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2ufcm4 | If the y chromosome is human specific what causes the differentiation of male and female apes? | I guess I just want my confusion cleared up on this article about the y chromosome Adam... Was the y chromosome due to the fusion of apes 24 chromosomes into our 23?
Here's the article: _URL_0_ | askscience | http://www.reddit.com/r/askscience/comments/2ufcm4/if_the_y_chromosome_is_human_specific_what_causes/ | {
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"The Y chromosome originally evolved from an autosome which acquired sex-determining characteristics. Apes also have X and Y chromosomes; in fact, many vertebrates do - mice have XY (male) and XX (female), birds have ZZ (male) and ZW (female). \n\nSome vertebrates don't have their sex determined in this way. Often, environmental facts play a major role such as the temperature-dependence of sex determination in crocodilians.\n\n[This](_URL_0_) is a great place to start for getting your head around the origin of the Y chromosome. Fascinating stuff."
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8vomp8 | why does using a tootbrush how we do not make us sick? it is never sanitised and sit in your bathroom all day. | Sorry about the terrible title I posted right before I went to sleep after I brushed my teeth. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/8vomp8/eli5_why_does_using_a_tootbrush_how_we_do_not/ | {
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"Not to mention every time you flush with the lid up the flushing motion causes tons of tiny poo particles to be thrown in the air which settles on anything nearby, such as a tooth brush.\n\nThe immune system is fighting off infection 24/7. Not just when you contract a disease. Plus the bristles are plastic, designed to resist contamination. And you generally rinse it off before and after each use.\n\nBut still is why you need a new one every couple months.",
"A tooth brush is not a disinfecting agent. It's meant to scrape away excess food, not kill bacteria. Your mouth is ahead good enough at dealing with bacteria; removing excess carbohydrates by brushing just limits bacterial growth.",
"Soap, your faucet, your tooth brush, the glass you drink water out of, all has bacteria on it. We don't live in a sterile environment and we ourselves are not sterile. You have more bacteria in your mouth, and fungal spores, than on your tooth brush. \n\nHaving bacteria isn't the problem, it's having a place for bacteria to multiply and grow into a colony unopposed and for that you need food, water, shelter, and no competition. Your tooth brush has only one of those things. \n\nThe job of a tooth brush is not to sterilize your mouth, it's to wash away the metabolic junk and plaque that eats away at your teeth. It denies the colonies in your mouth food and a medium to safely grow in (plaque). ",
"Might not be relevant, but I dip my tooth brush in listerine for a minute every other week ........ 99.9 percent effective ",
"Your mouth is dirtier than your toothbrush. The longer you go without brushing your teeth, the cleaner your toothbrush is. Your mouth is the contaminant. Not dissing anyone's specific mouth - this applies to all humans.",
"Sure, your toothbrush is full of germs, but they're *your* germs (unless someone else is using your toothbrush). ",
"Same reason toddlers don't sporadically die even though they put all kinds of random shit in their mouths when you aren't looking.\n\n\nIf we were reliant on our own sanitation efforts to keep from getting sick (washing our hands, sterilizing eating utensils etc.) we would be long since dead.\n\n\nIt feels good to wash your hands and feel like all the evil bacteria is gone, but that's mostly naive first world logic, its not that simple. And someday we may arrive at the collective conclusion that antibacterial soaps are simply not necessary for everyday use (discounting things like surgery, idk).",
"A few things:\n\n* Toothbrushes are cleaner than you think; most dangerous bacteria needs moisture and nourishment to survive, and really only replicates quickly in warmth. Your toothbrush dries out, is (hopefully) rinsed thoroughly to limit resources for the bacteria to thrive on, etc.\n\n* Your immune system is amazing; it's a lot harder to get sick from exposure to bacteria than you imagine. If it *weren't*, you'd be constantly sick.\n\n* Most of the bacteria on your toothbrush isn't novel; the bacteria in the bathroom is mostly stuff you and your housemates have already been exposed to, and which your immune system is therefore already dealing with. Having a bit on your toothbrush isn't likely to significantly alter your risk.\n\nThat said, it's pretty easy to disinfect a toothbrush by swishing it in an antiseptic mouthwash (e.g. listerine) for 60 seconds, so if it's a worry, it's easy to mitigate the risk.",
"Because in general modern society is excessively paranoid about germs but our bodies are exceptionally good at not getting sick. ",
"Because there's nothing on your toothbrush that isn't already in your body.\n\nYou know you can walk outside and eat dirt and be fine right? Kids do it all the time.\n\nYour body has a robust immune system.",
"Ye the bacteria are strong, but fear not your immune system is stronger. I mean your mouth is covered in bacteria too. Not all bacteria is bad bacteria and your body has ways of kind of keeping bacteria out of where it's supposed to be."
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22sy1f | Historiography question: what do you consider determinism/causality? | This question is sparked by a discussion of *Guns, Germs, and Steel*, but it is not a continuation of that discussion. A complaint was made that Diamond presented determinism and that got me wondering. I know the philosophical discussions regarding determinism and free will and such, I wondered what historians here think about the topic. What is too deterministic? Or where can we identify historical causality?
My position is that I see history moving from a humanity to a science. That if we find cause we find cause. Sometimes an individual is critical and agency matters, sometimes it does not.
I would say this is most clear in history of science. Maxwell was a genius, Einstein was a genius. But if neither one of them lived physics today would be pretty much the same with the same equations. The path would be different and certainly it is the job of historians to document and understand those paths, but we would get to the same place.
| AskHistorians | http://www.reddit.com/r/AskHistorians/comments/22sy1f/historiography_question_what_do_you_consider/ | {
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1mycgj | what are the reasons as to why the oil price never return to $1 range since 9/11? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1mycgj/eli5what_are_the_reasons_as_to_why_the_oil_price/ | {
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"The specifics about why gas prices go up can be better explained by others, but this chart shows gas prices adjusted for inflation:\n\n_URL_0_\n\nIt seems like the climb started closer to 1999 than 2001, but asking why it hasn't gone back done since then is a great question.",
"two big reasons. China and India are industrializing at an amazing rate, using more petroleum for industry and also for autos as the middle class moves up. But the biggest reason is that people will gladly pay a great deal more for gas. SInce they can sell all they want at $3.50/gal why would they lower the price to $1? ",
"Because they've discovered that demand will sustain $3.00+ conditions. If they thought they could get away with anything higher, they would. And, they will soon.\n\nIf you were selling lemonade (and were evil) you rely on lemons. If you're grocer was cheating with his produce supplier's wife, there might be concern in your community about the availability of lemons. With summer approaching, people would be very willing to pay $2 for a lemonade they paid $1 for last year. Eventually your grocer would find a new fruit source and lemon supply would return. But, people are now used to paying $2 a glass, so....... yeah.",
"Because oil companies are greedy. Record high profits while charging record high prices, but the oil companies will tell you that the price of gas has nothing to do with their profits."
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33h6wm | What happens to electrons in a circuit? | I've always had a really hard time understanding how electricity really works. I'm trying to understand how a circuit works but here is what I don't understand: Does electrons or charge get "lost" during the process thanks to resistance or do all electrons all eventually make through from on pole to the other? If they don't make it all the way through, where do they end up? What happens to them?
Another question is regarding the potential energy stored in the electrons. When that energy is harnessed to power things, what happens to the electron? My understanding is that the potential energy of the electron is what drives it to move from one pole to the other. When that energy is depleted or lost, does the electron simply stop and get trapped in the cable or slow down or what happens?
I'm eternally greatful for any answers that can give me some insight into this matter! | askscience | http://www.reddit.com/r/askscience/comments/33h6wm/what_happens_to_electrons_in_a_circuit/ | {
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"For the purposes of circuits, electricity works a lot like a pneumatic system. With wire there will be electrons in all the places at the same time. If power gets used up, to useful work or to resistance it does so in the form of a 'pressure drop' but the electrons are still around.\n\nThe actual net movement of the electrons is typically quite slow:\n_URL_0_",
"So in metals, there is a large amount of electrons in the \"conduction band\" (the outer electron shells), and these electrons can freely move throughout the whole metal. They are doing this all the time, just whizzing around randomly like molecules in a liquid. When you apply a Voltage (say, using a 9V battery), the electrons are all subjected to a field and they begin to move a little more in the direction of lower potential energy (towards the positive terminal of your battery). So a single electron is suddenly flying towards the positive terminal of the battery, zooming along through the metal. But then, a tiny distance later, it bumps into a defect in the metal (which are abundant) and loses most of its kinetic energy, which goes into vibrating the metallic atoms and creating a phonon (read: thermal energy in the metal). Then the electron is off on its journey again, as the electric field in the metal accelerates it. This is all very exciting, but on a macroscopic scale, the electrons are moving very slowly; however, there are a lot of them and the net movement of charge is significant, enough to power a lightbulb or a motor. No electrons or charges are lost, because your battery is supplying electrons at the negative terminal for every electron that is sucked into the positive terminal of the battery. Eventually, the chemicals in the battery are no longer imbalanced and there is no longer any potential difference between the positive and negative ends of the battery--all the extra electrons in the negative side are now in the positive side and the battery is \"dead\", but the wire still has the same number of electrons that it started with! As to the potential energy--it really comes from the original imbalance in the battery that creates the field that moves the electrons. After the energy is depleted, the electrons no longer feel any force in any particular direction and they go back to their random motion."
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4dh5cd | how exactly do people avoid taxes using shell companies? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/4dh5cd/eli5_how_exactly_do_people_avoid_taxes_using/ | {
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"Let's say you own a pretty profitable business in the US but you're tired of paying taxes. First, you make a shell company where there are lax regulations and low taxes. Then you transfer the assets that your US company has to the shell company, in name at least. You continue to use those assets in the US to make money and do business, but all the money technically belongs to your shell company. Since your shell company is outside of the US, it doesn't pay US taxes. \n\nThe tricky part is being able to use assets outside of the US to do business in the US without having to keep the money in the US. There are different ways to get around this. For example, a tech company can transfer all of its patents to its shell company and then the US company can lease them back under terms where money made from their sale belongs to the shell company. ",
"You transfer assets out of the real company, to make it look like it didn't make any money, and put them in the shell company.\n\nThen the shell company doesn't pay taxes. You could just not file, and shut it down before you get caught. \n\nOr you could put the shell company in another country, and make that money and your association with it hard to trace."
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2jqt9h | pigs are considered fairly intelligent animals. why are people who abhor eating dogs, cats, horses and whales for moral reasons fine with eating pork? | I'm looking for a better explanation than "Because bacon" | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2jqt9h/eli5pigs_are_considered_fairly_intelligent/ | {
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"Because pigs rarely have a use outside of their use as food. Sometimes they are bred to hunt for truffles and other fungus/plants, but aside from that, their characteristics make them ideal as a food source.\n\n* Grow quickly\n* Eat anything\n* Don't require much space\n* Gain lots of meat in a small amount of time\n\nThat second part \"Eat anything\" is actually the reason why Jews and Muslims don't eat pork. Pigs were scavengers in the areas where Abrahamic faiths are indigenous to, and as such they would eat the garbage and therefore were considered unclean, despite the fact that they are remarkably hygienic animals.\n\nWhereas while dogs, cats and horses share some of these traits, they generally are more viable to be used for other means.\n\nDogs\n\n* Hunting companions\n* Shepherd companions\n* Security/protection\n* Don't grow as quickly\n* Not as much of a varied diet\n\nCats are almost solely kept around as mousers, they would eat mice, rats, any rodent really, as well as insects and other small animals. This would result in less rats, mice, etc. to carry disease or get into food stores, therefore more food for us humans, and less disease. They were also very good when kept in a home in order to know when something was to happen as they can sense things we can't.\n\nHorses have been used for travel, as beasts of burden and symbols of wealth and power for thousands of years. They took a while to grow and didn't produce a large enough amount of meat compared to what it took to raise them for them to be a viable mass food source. They are a delicacy in some countries, and even then they take in horses that are lame, or died in accidents to be butchered.\n\nWe don't eat whales because it's a pain to get them, they are almost extinct and serve a massive role in the oceans' ecosystems.",
"You're really not going to find much of a good reason for why we see some animals as deserving of rights and protection and some as being hardly better than inanimate objects. I'd say the average cow isn't any dumber or less able to feel pain or understand their captivity than the average dog, but if that means never eating beef again, you'll find that a majority of people won't find this reasoning convincing enough. \n\nSame with whales. Whales are extremely intelligent and some are forced to live in tiny pools and do tricks for our entertainment. Probably the only reason there's such a robust movement to protect whales is because they're endangered. If whales were common like cows are, we'd probably have much less of a problem killing them.\n\nUltimately, there are only two logically consistent positions: veganism or accepting that there's absolutely no moral reason not to kill animals for any reason. I'm not even a vegan myself. I'm just saying, anyone who can justify eating meat but also opposing some forms of animal cruelty is tricking themselves. "
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c7aij8 | why stab wounds in movies appear to be deadlier than gunshot wounds (at least in movies) | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/c7aij8/eli5_why_stab_wounds_in_movies_appear_to_be/ | {
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"It's all about what's convenient for the story. Bad guys get shot and they are instantly dead. Good guys get shot and they can run a marathon.\n\nThere is no consistent logic even within the same movie. As long as it doesn't break the suspension if disbelief, writers and directors do what moves the story in the direction they like",
"They both obey the same laws:\n\nIf it hits an artery/heart, you're dead 99% of the time\n\nIf it hits a major organ, there's a high chance of death unless treated immediately. \n\nIt's just stabbing is more accurate than shooting.",
"Knife fights and stabbing are often more \"personal\" conflicts that are supposed to cause more tension emotional distress in the viewer. In keeping with this perception of raised stakes, they will often be depicted as fatal.",
"It depends on a lot of factors, but personally I'd MUCH rather take my chances getting stabbed than shot. Knives make much cleaner wounds with a lot less energy than bullets, are less likely to shatter bone and tear tissues beyond what you see with the entry wound, and have inherently limited depth depending on the blade. Others have commented how in film and TV, the relative deadliness of a knife vs gun wound has much more to do with the demands of the plot than what happens in real life. I find it very believable that gunshot wounds to the abdomen are deadlier than stab wounds - gunshots are more likely to damage one of the several huge arteries and veins in the abdomen, relative to a knife, and the damage they do is more difficult to repair in the trauma bay.\n\n & #x200B;\n\nIf YOU get stabbed, the absolute number 1 most important thing to do is STOP THE BLEEDING. Blood loss is the most common cause of immediate death from stab wounds, bar none - especially if the stab is in the gut. Cutting into intestines can kill from infection, but this takes days to weeks; dying from blood loss due to a major artery in the abdomen can take seconds. Other targets - the liver, pancreas, kidneys, stomach, spleen - all have really significant risks when damaged, but none as immediate and high-stakes as blood loss (and, for many of them - i.e. the spleen, kidneys and liver - blood loss IS one of those risks, as they bleed profusely when damaged). Find the hole where blood is coming out, and apply as much direct pressure to it as you can to stop it until EMTs get there. This is why one important rule is to never remove the object that caused the wound, if you can avoid it - the knife or whatever could be helping to stop blood coming out of the vein or artery it's stuck in.",
"I have been an ER nurse for 25 years and one thing I have learned in that time is that if a woman comes at you with a knife, run! She will kill you! \n\nI have seen far too many deaths from stab wounds compared to gun shots. The majority of them have severed aortas, pulmonary arteries, superior vena cava, etc. Most gun shot wounds tend to hit extremities or in the back (which causes other issues). \n\nAlmost every stabbing victim I have treated was attacked by a woman. I had a guy in the other day who was stabbed by a woman. She severed his pulmonary artery. He died in the trauma room. We got him back. He was in for a follow up because he thought his wound was infected. \n\nMaybe I should put this in /r/life tips but if you have pissed off a woman enough that she comes at you with a knife, run like hell, your life depends on it."
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19hqkd | how does the susan g komen foundation steal so much money without anybody getting upset about it? | *braces for grammar-impact for ending with a preposition*
More specifically, what were the numbers involved in the scandal? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/19hqkd/eli5_how_does_the_susan_g_komen_foundation_steal/ | {
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"people stop caring after they make their donation. No one ever cares where the money goes after they give it, they just give it to feel good about themselves, not to actually do any real good. It is all about perception, and perception is reality.",
"\"It\" is a pronoun, not a preposition.\n\nAlso, \"don't end questions with a preposition\" is a questionable rule at best, and just plain made up at worst, depending on which grammarians you ask."
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19c682 | why do people want programming taught in elementary/high schools? | I know absolutely nothing about programming.
EDIT: I'm marking this as answered. Thanks to everyone who replied! | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/19c682/eli5_why_do_people_want_programming_taught_in/ | {
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"Because it's a skill which has lots of real-world use, and which, like many skills, is easier to teach to children than adults.",
"It promotes good thinking habits. ",
"It's a good way to teach someone a different method of logical reasoning. Same reason they teach higher level math. Are you REALLY going to need advanced algebra in your daily life? Nope! \n\nAre you going to learn how to program your own operating system in high school? nah!\n\nI think of programming like another universe. The laws are different. You have to learn the laws and learn to think in that universe. \n\nFor instance, an exclusive or: _URL_0_\n\nXOR as it's called. \"This OR that but not both\". \"Do you have an apple or an orange\". note the question is asking in the singular. Both isn't an acceptable answer and neither is none. The answer can only be apple or orange. ",
"Been advocating this too.\n\n1) As a proxy for learning problem solving and overcoming setbacks in a logical, highly teachable way that's full of immediate feedback. Mastering those two things can mean the difference between seeing the world as a place full of solvable problems or as an incomprehensible pile of magic and mess. \n\n2) If you get good at it and enjoy it, then do it professionally, you're less likely to ever have to worry about a job (or being trapped in a job) than many other people. \n",
"It should be an elective, but I see no qualms offering it to students. It'll give a 13 year a head start in a field they might be interested in, and a reason to stay in school. ",
"I took computer programming in high school as an alternative to calculus.\n\nIt's a challenge getting through my daily life without knowing calculus, but I cope the best I can. With the money I make as a computer programmer.",
"Programming teaches people that if something is wrong, 99% of the time 1) it was the coder's fault, 2) it's due to lack of attention to details, and 3) there is a logical (and often elegant) solution. It teaches that complex systems can be broken down into smaller parts. It forces objectivity and reasoned analysis. Magical thinking is punished.\n\nThe learning experiences gained through programming are valuable in many disciplines and life in general.",
"Critical thinking and problem solving.",
"A computer litterate nation is better than an illiterate one. ",
"_URL_1_\n\nHere's a nice little video by _URL_0_ that addresses that very issue. It features people like Bill Gates, Mark Zuckerberg and _URL_2_.",
"Programming is a subset of computer skills that are required in the real world. Computers are everywhere. I'm a computer science (programming) major in college that works for IT (fixing broken computers). The lack of understanding by even many university professors is incredible. The current system for learning to computer is poor, at best.\n\nSecondly, programming doesn't just mean, \"oh, look at that nerd writing Java programs\". Excel allows for many commands, and is a major tool used by almost every company at many levels. Knowing how to use this program more effectively is a huge asset.\n\nFor most things people use, individuals take the time to educate themselves about the product at some level. I drive a car- I know I need to get my oil changed regularly and which gas to get and the difference between brands and engine types. Not at the level of a mechanic, but I know enough to have a high level conversation with one to discuss my issues. I talk to many people about computers, and ask if they've \"installed drivers\" or to \"find their ip address\" (relatively simple tasks), and they don't even know where to look.\n\nWith as prevalent as computers are today (everywhere), people just need to be more educated, early, about computers in a manner that just isn't taught today. Programming is one aspect of that.",
"One of the biggest reasons people want programming taught is because programming isn't exactly what you think it is. Programming is problem solving. I work with visual studio mostly and there is a reason that the name we use for a new project is a *\"Solution\"*.\n\nEverything I do is a problem. You come to me and say you want a website. Before I would think \"Ok so I need html, uh I need a domain\" etc etc. As I got more into programming and better at it I learned all I was doing was solving problems. So when you say you want a website what you are actually saying is that you have a problem. The nature and solution to your problem is my skill. You don't want a website you want me to build something to fit a need you have. The problem is that you do not have a tool to get what you want, so I build you the tool that gives you what you want.\n\nSo I will begin asking you questions. They will seem strange. I won't ask about color schemes or trends yet. I need to figure out what you want and you can't tell me that. You don't know. Thats what I do. You tell me the vague goal you want and I probe and prod and solve **you**, to solve your problem.\n\nCode and the languages themselves are just my tools. I am skilled with them and understand them. But the difference between someone who knows how to code and what I would call a programmer is the same between a carpenter and a person who owns a hammer. You do not pay for my tools. You pay for my mind and I use my tools to solve your problem, the same as you pay a carpenter for how he uses the tool, not how long he's been using the tool.\n\nThe reason that programming is so much better at teaching problem solving is because of a concept known as abstraction. Abstraction is confusing because it's used for a lot of things. We associate it with so many concepts it's tough to know if you don't look for it. But abstraction is easy. You already know it. If I showed you a desk chair and asked you to tell me what it was you could do it easily. Now if I showed you a recliner and asked you what it was; again no problem. Now if I asked you what both were then you would tell me they were both chairs. That's it right there. You can tell me that they are clearly different and yet the same. So if you had to tell me about both chairs we can figure out what they have in common (back, bottom, support, seat, material) and what was different (recliner part, wheels). Abstraction is just saying. These things all fit into a group I call this. So desk chair is a chair which is a piece of furniture.\n\nThis is what is needed in problem solving. You have to understand incredibly in depth what makes things the same and what makes them different. You have to be able to take something real (a deskchair) and understand what is abstract about it and what is real (the chair is really made of leather and metal) and what is abstract (the name \"desk chair\") is abstract it could be called anything yet we need to understand how both of those concepts work in order to understand a chair.\n\nSo learning programming allows you to make connections and associations. Along with that it allows you to understand hierarchies and scopes of problems. It gives you language to express problems. So I can think and plain intelligently my approach to a solution because I have a way of expressing any problem. I can do it with anything. You have a social problem? I can deconstruct the components and give form to the problem. I can literally pull out all of the information and then provide any solution for you.\n\nProgramming just gives you access to that world. This magic box in front of you is capable of generating an almost infinite amount of imagery. Those pixels you are reading this with can be rearranged IN ANY WAY!! All you need to know is how to get them to do that. And you do that by learning to program. So it not only teaches you how to solve problems but gives you a virtual environment in which you can recreate and test and test and test. You can do anything that your computer can process.\n\n**TL;DR Why the hell would you not want to know how to virtually become a magician?**",
"Because if you understand how to code, you can basically do anything you can imagine. You will also learn that it's not hard.",
"It's more about learning logic than just making things pop up on a screen.",
"If you can program a solution method, you understand the problem. \n\nI firmly believe this is the way math should be taught. Repetition on an abstract idea doesn't really help. Learning good problem solving in a practical way does. That's why no-calculator tests always bothered me. Really? I'm going to be doing this level of math without one ever?\n\nWhen people talk about programming, they don't necessarily mean graphics, web, all of that - that kind of practical programming isn't necessary for everyone. They mean using programs that can ready simple commands to solve simple programs, like Matlab. ",
"You know people who 'aren't good at computers' and how they generally suck at a lot of other things too? Well by the time kids today are job age tomorrow, they's gonna need it. \n\n**TLDR:** The world is only getting more and more computery, son. You don't wanna end up like lazy uncle Joe.",
" > I know absolutely nothing about programming.\n\nI feel like you answered your own question.\n\nComputer literacy is important. Browse r/talesfromtechsupport and see the stupidity that those people have to deal with on a daily basis. If you're computer literate, your productivity shoots up tremendously, since there are all these computer programs that do just that! Besides, since computers are so useful, *you're* only useful if you know how to use them. Even a cashier needs to be able to handle numbers and computers. Nearly every facet of our lives is centered on, or at least informed by, computers.\n\nIf being able to use computers is like reading, then programming is like writing. Even more than that, programming is a language you use to solve problems. And just like with English, if you can *think* in programming, your universe is much bigger. Would you be able to think of, say, the US Constitution without language? It's a document, but it's also the framework of a government. Maybe you can imagine a picture of the US Constitution, and maybe comprehend some of what it means, but without language, you won't get very far! Programming is like that, but it's a different language for a different problem space.\n\nThe thing is, math is *abstract*. You learn how to add and divide, but for what? What good is factoring polynomials? It's easy to treat math as something you have to do for school that you never want to see again. Programming is something with obvious applications *right now*, and it's fun, too, since you get to build and create things. Programming *forces* you to think logically and to pay very careful attention to details, because otherwise, things just don't work. Programming is the culmination of what our logical-leaning education is *supposed* to be.\n\nAnd, very importantly, jobs require programming. Lots of them. If you're a bad programmer, that's OK; at least you know the basics and can understand what's going on if you need to. If you don't program at all, though, a large share of the world is just unavailable to you. The barriers are just too high when you don't program at all."
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5vrzqh | why do people in the americas greet eachother with one kiss on the cheek while in europe they greet eachother with two kisses on each cheek? | I am aware not every nation in either continent does this, and I am also aware that it depends on region. It gets the point across. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/5vrzqh/eli5_why_do_people_in_the_americas_greet/ | {
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"Americans do not, on average, kiss each other on the cheek when meeting. Since the most common is zero, one seems like plenty.\n\nIn a culture where kissing on the cheek is common, two does not seem like an excess. ",
"I do not greet people with one kiss on the cheek, and I'd think you were weird if you were also an American and greeted me with a kiss on the cheek.\n\nA handshake will do if it's formal. A hug if you're family or a close friend. A simple vocal greeting will do just fine otherwise."
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[],
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b5w9aw | is there any difference between getting injections(of vitamins,medicine etc.) directly into your veins or into your muscle(most commonly butt muscle)? | Simply,I had the same stuff injected to me both ways and I wish to know what's the difference? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/b5w9aw/eli5_is_there_any_difference_between_getting/ | {
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"Some things, like vaccines, are best injected into muscles due to the way they are made and engineered to work.\n\nOthers are injected into veins for quick distribution. Because vaccines do not need to be so rapidly distributed they do not need to directly enter the bloodstream.\n\nAs to why they did both for you, it could be that you need some now and some long lasting treatment."
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wvtzg | Where does helium in natural gas come from? | Most helium in the world is produced as a [byproduct of natural gas](_URL_0_) However most of the components of natural gas and other fossil fuels appear to be things that can degrade from life and migrate into reservoir traps (hydrogen, carbon, nitrogen, sulfur etc). So my question is what actually produces or releases helium so that it can migrate up and be trapped with natural gas? | askscience | http://www.reddit.com/r/askscience/comments/wvtzg/where_does_helium_in_natural_gas_come_from/ | {
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"Alpha particle decay of naturally occuring radioactive elements, such as Uranium. The alpha particle is a helium nucleus. ",
"_URL_0_\n\n > Most terrestrial helium present today is created by the natural radioactive decay of heavy radioactive elements (thorium and uranium), as the alpha particles emitted by such decays consist of helium-4 nuclei. This radiogenic helium is trapped with natural gas in concentrations up to 7% by volume, from which it is extracted commercially by a low-temperature separation process called fractional distillation."
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20v4jt | why is contact lens solution so friggin' expensive? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/20v4jt/eli5_why_is_contact_lens_solution_so_friggin/ | {
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"Because people need it and will buy it at any price. Like gas.",
"It's a sterile product that people are putting in their eyes. Lots of liability if someone gets an infection."
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1jwcez | how do "non-profit" organizations have some of the highest paying internships / job positions? | A friend of mine just told me he was offered a job with a non for profit making about 65K a year, and I didn't feel comfortable asking how the hell...? If they're making no profit's, is it all donations? Thanks | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1jwcez/eli5how_do_nonprofit_organizations_have_some_of/ | {
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"The company itself doesn't post a profit, meaning that any money it gets over its budget/operating cost (including employee salaries) must be given away/not used for company benefit. While it may seem counter-intuitive, non-profits do need to maintain competitive pay rates to attract talent necessary to maintain an effective business.",
"Non-profit just means that instead of the company paying out profits to employees (in the form of bonuses) or to investors (e.g. through dividends) as regular corporations do, non-profit organizations instead re-invest all the 'profit' they make back into the company to improve its products and services. It basically just means the organization is committed to only spend excess money on advancing the corporation in meeting its long-term goals and mission statement. Not for profits are required to comply with a number of government regulations which require them to be very open and transparent about their 'business practices' and finances to ensure they are not abusing their non-profit status.\n\nDo note that non-profit organizations are still allowed to pay salaries like normal companies. All that matters is that whatever is left over after covering expenses (including but not limited to salary-pay), must then be reinvested back into the corporation. So they can still have salaries, they just can't pay bonuses that are dependent on how much money the organization makes that year.\n\nIt's also important to distinguish between non-profit and charity. A charity is simply a type of non-profit organization that does free work (e.g. helping the poor) and is funded primarily through donations. There are however other non-profit organizations that look and act just like companies and offer regular products and services for a fee, it's just that they don't take home the profits in the form of bonuses and dividends."
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5imzfv | why do elderly people die from simple falls? | I'm not referring to directly traumatic falls here, like if they fall and hit their head and suffer brain damage.
Why do elderly people die from falling (directly, i.e. the fall causes lethal health complications, or indirectly, i.e. they are injured in some other way and die in the course of trying to treat that injury), when an identical fall would barely even injure someone younger?
I know that when you get old your bones become significantly more porous and it becomes easier to *break* them, but I'm having trouble making a connection between things like Grandma Betsy falling and bruising her hip or spraining her ankle on Day 1, and then subsequently passing away on Day 4. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/5imzfv/eli5_why_do_elderly_people_die_from_simple_falls/ | {
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"Healing wounds takes a lot of energy and resources for the body, and as a person gets older there's less to go around for normal processes if something does happen. Bones, muscles, and organs all get weaker and less effective at their jobs, just like in a mechanical system when parts fail and degrade.",
"A hip repair is a big fucking surgery. \n\nA lot of energy goes into healing that type of injury. \n\nOlder bodies simply don't work as well as younger bodies. \n\nYou could have internal bleeding. Infection. Organ failure from shock. You name it. \n\n",
" > when an identical fall would barely even injure someone younger?\n\nBecause often it is not an identical fall.\n\nA healthy person will likely have the strength, reflexes, balance, and agility to partially recover, and minimize the damage of fall. You put a hand out, aim for something soft, or twist so you land on your side or butt. \n\nAn elderly person taking the same fall might not be able to any of these things, and wind up falling harder, landing on a more vulnerable area, and hurting something vital.",
"Advanced Age + Fall = Death\n\nMortality comes from:\n\n1) deadly blood clots (as a direct complication of any broken bones) which can then travel around the body (think heart, brain and lungs) and cause further fatal damage like heart attacks, strokes\n2) deadly hospital-related infections while undergoing treatment for the fall\n\nThere are also complications from de-conditioning from being immobilized after the fall, which leads to skin break down from being bed-bound, and overall failure to recover.\n\nElderly people have less \"reserve\" than younger people, and it can be very hard to bounce back from a serious fall. This lack of reserve means they have less strength/flexibility, tend to be malnourished, and perhaps have weaker immune responses to begin with when they fall. \n\nYou'd be amazed by how deadly even a ground-level fall can be for a patient."
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rfnu0 | how does a on-time pad work? | _URL_0_
One time pad* Sorry! | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/rfnu0/eli5_how_does_a_ontime_pad_work/ | {
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"All codes work by changing some piece of information. Because of the change it is hard to tell what the original information was. For instance if I change some word into \"xxr\" what was the original word? \n\nWell a one time pad is a way of changing information that never repeats any pattern,, that means you can never predict how information is or was changed. That means you can never decode \"xxr\" because you can never guess what I did and I will never do it again, I did it \"one time\"."
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2g8bnn | why airline frequent flyer programs have been made so difficult? | Why the airlines don't reward points automatically? I can understand that some may want to register the points for another airline in the same alliance, but why not those airlines not in any alliance do it always automatically?
Why I can't register reward points right after I've used my ticket? Why do I have to wait for like a week in order to register? However, if I show my loyalty card at check-in desk, the points get registered. Sometimes I forget to show my card, but my card is never asked, why? Grocery stores always ask my card.
I flew with a new company and then tried to register the points. However, this company didn't allow to register afterwards like all other airlines. They didn't notify me at any point about this. It's like they don't even want me to register the points. Why?
I was able to collect enough points to upgrade the program. Then in an airport at the service desk I asked them to get me a new card. Their reaction was a bit rude "we can't help you". This is just a single case, but the feeling I get overall is that the airlines don't seem to care about their customers regarding the loyalty programs. Why?
| explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2g8bnn/eli5_why_airline_frequent_flyer_programs_have/ | {
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di4sdf | Can a person sense light if he/she is asleep? | Hypothetically say, they lack an eyelid and fell asleep and don't get disturbed, will they still be able to sense light ? | askscience | https://www.reddit.com/r/askscience/comments/di4sdf/can_a_person_sense_light_if_heshe_is_asleep/ | {
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"You can sense light through your eyelids while closed, although you may not be consciously aware of it. Light signals your body to stop producing (or secreting) melatonin, enabling you to wake up more readily. This is how the lamps that use simulated sunlight help you gently wake up."
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6pwn7n | how do telescopes that capture images very far away (hundreds of light years) get a good sharp shot when you know that the earth rotates slowly | Because you're looking at a very tiny spot in space very far away, the rotation of the earth would cause it to move out of frame in just a second wouldn't it? Do telescopes move with it when looking at that point? Or are pictures from that far away taken with the hubble telescope that doesn't rotate with the earth (of course it orbits but still pointed in one direction) | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/6pwn7n/eli5_how_do_telescopes_that_capture_images_very/ | {
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"Extremely high-quality images are taken with orbital telescopes. Even if you compensate for Earth's motion, the atmosphere imposes a limit on the quality of pictures we can take from Earth's surface.\n\nBut yes, the best telescopes we do have on the surface of Earth compensate for its motion. "
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2iutms | FAQ Friday: Ask your questions about the Ebola epidemic here! | There are many questions surrounding the ongoing Ebola crisis, and at /r/AskScience we would like to do our part to offer accurate information about the many aspects of this outbreak. **Our experts will be here to answer your questions, including:**
- The illness itself
- The public health response
- The active surveillance methods being used in the field
- Caring for an Ebola patient within a modern healthcare system
**Answers to some frequently asked questions:**
- [Could Ebola become airborne?](_URL_6_)
- [How do we know patients are only contagious when they show symptoms?](_URL_7_)
- [What makes Ebola so lethal? How much is it likely to spread?](_URL_4_)
- [Why can't mosquitoes transmit Ebola?](_URL_0_)
---
**Other Resources**
- [Recent AMA in /r/science](_URL_8_)
- [AMA in /r/IAMA from Estrella Lasry, Tropical Medicine Advisor for Doctors Without Borders](_URL_2_)
- Informational pages from the [WHO](_URL_5_) and [CDC](_URL_1_)
---
This thread has been marked with the "Sources Required" flair, which means that answers to questions *must* contain citations. Information on our source policy is [here](_URL_3_).
As always, please do not post any anecdotes or personal medical information. Thank you! | askscience | http://www.reddit.com/r/askscience/comments/2iutms/faq_friday_ask_your_questions_about_the_ebola/ | {
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"I'm somewhat familiar with the symptoms, but how does Ebola actually kill victims? (I.e. you don't die of Ebola, but of dehydration due to Ebola)",
"I'm going to be traveling to Morocco over the summer. It is at the northwest corner of Africa. Should I be worried? The healthcare system there isn't the best. In a nutshell, what are the chances of the disease spreading to other parts of Africa?",
"How likely is it to spread in a first world country? Could it ever reach epidemic proportions with our level of hygiene?",
"How far out is a vaccine? What steps are left in making one available to the public? It seems to me like as soon as a vaccine is generally available then the risk of wide spread panic should go away.",
"What are the chances of Ebola becoming a pandemic here in the US? My dad is already really freaked out by the possibility and is preparing for the worst cast scenario. ",
"I keep hearing that Ebola is not infectious while asymptomatic, but have been unable to find any sources or papers that back this up. Is it truly noninfectious, or does it just have a drastically reduced infectivity than compared to when symptoms emerge?",
"I saw that post yesterday mentioning 55% of Americans want to cancel flights coming into the US from ebola stricken African countries..\n\nDoes the government take note of these polls? If so, do they need or want a 75% agreement? What percentage would it take for the government to actually listen, or do they not really care what US citizens believe regarding this? & thanks in advance. ",
"Every year during the Christmas present buying season, we see a huge rise in flu bugs, colds, the winter vomiting bug etc, purely because of the amount of people out and about. These bugs are all spread by poor personal hygiene. Should we be worried by Ebola at this time of year? Does it have the potential to spread in the same manner? Could it evolve to spread this way? Thank you! ",
"How much of a 'crisis' is this i.e. how far has this been blown out of proportion by the media? I guess the main point being, to what extent do we have this under control, especially with safeguards being put in place to control the spread to the West?",
"Could ebola cross into other species?\n\nCould bats in the US become carriers? What about ticks? Or farm livestock?",
"If you touch something with the ebola virus on it (a dirty tissue), do you automatically get ebola? Or is there some way to get it off your hand? If someone with ebola bled on the floor, is there something that can clean up the blood and the virus? Or will the virus be on the floor for however many days it takes to die off? ",
"Hi everybody! \n\nI just posted this same set of questions in Mark Fielder's AMA, but I'd appreciate getting a wider range of answers (and there's no certainty he'll choose to answer my question - but if he does, I'll share his answer here). \n\nMedia seems to be assuming a high rate of mutation for the Ebola virus, but there seems to be very little difference between this outbreak and previous ones in terms of virulence. Most of the high transmission rate seems to be arising from social practices, rather than a more infectious virus. \n\nSo my questions are: \n\n1. In the current outbreak of the Ebola virus, is the virus actually more virulent than in previous outbreaks?\n\n2. What is known about the rate of mutation of the Ebola virus? \n\n3. There is political movement in the US to stop all flights from the 3 most affected African countries. Do you think this is necessary? Is screening travelers for fever effective, or should all travel be stopped? ",
"Where can we find ongoing comprehensive factual information regarding:\n\n* Where are there ongoing cases of Ebola?\n\n* How many suspected cases are there inside the US?\n\n* How many people are being observed in the US who may have come in contact with an Ebola patient?\n\n* What transmissions vectors exist outside of Africa? Have any international airports closed down, etc.\n\n* A history of Ebola cases leaving Africa or being diagnosed outside of Africa.\n\n* What procedures or steps in place are there with hospitals / healthcare professionals? \n\n* Which airports / international transmission vectors are currently being monitored?\n\nI gave a speech on Ebola yesterday and have another next week and I'd like to ensure I'm both accurate and up to date (and not needing to splice together 50 sources)",
"I read today about US Marines arriving in Liberia to help build clinics. What can they do to prevent being infected with Ebola?",
"(1) Is the average United States hospital capable of dealing with patients in large quantities? \n(2) Do patients require very specialized care once we get basic protocol down\n(3) With the current projection of infection rates, is it likely we're going to see many more pockets of infected around the world? ",
"What is the treatment procedure for Ebola patients once admitted to the hospital?",
"I'm a flight attendant, and consequently fly to some moderate risk areas. Additionally I come into contact with bodily fluids A LOT more than you'd imagine (people are weird). What can I do to protect myself on flights? Also how could I spot someone with symptoms (apart from a high fever)? ",
"For this outbreak the reported fatality rate seems to be around 50-60% meaning that a lot of people actually have survived this nightmare. My question is about what shape these people are in when they are no longer testing positive for the virus? It seems some make a full recovery, but are there irreversible damage done to organs or other things that will effect survivors later in life?\n\n\nOr is it more likely that you either have < something > that makes you get rid of the virus in time, before serious damage are done, or you don't make it at all (and thus creating the image that surviving = full recovery)?\n\n\nI haven't found much written about survivors of the virus, except for some news stories about people that survived and now working with the medical effort (on the assumptions they have (some) immunity now).",
"Can someone explain how the current vaccines are targeting Ebola?\n\nI've been doing research on the structure of the virus and was wondering if any of the current trials are targeting the major proteins integrated in the virus namely VP40 and VP35. Also the mechanism of targeting glycoproteins on the cell surface. I was wondering if there are opinions on which targets are likely to be most successful in creating a vaccine or atleast a treatment. ",
"Is the virus affected by weather conditions? What I am trying to say is would higher parallels be safe in a hypothetical ebola outbreak?",
"Can ebola infect dogs and therefore be transmitted via dog-human?",
"Should United States citizens actually be as concerned about the disease as they are? I am aware Ebola is a deadly disease, but to me it seems like the media is playing on our fears, using a lot of \"what-ifs.\" However, whenever I search for info about the disease in the country, I find that we have experienced at most six cases, one death, and tons of negative tests. Everyone who comes into contact with victims are quarantined, but show no symptoms. It really seems like the country is keeping this pretty under control, and we are more scared than we should be.",
"The first question on the original post is about Ebola going airborne. My question is related. What's more likely, a deadly virus like Ebola mutating to become airborne or a mostly non deadly virus like influenza becoming as deadly as Ebola?\n\nIf these two things were basically as likely, it would be a good way to reduce the fear. After all most of us survive every year and influenza has not become really deadly in our lifetimes.",
"Can the ebola virus eventually mutate into an airborne virus? If so, how long could that take for it to mutate?",
"How accurate are computer models at predicting the spread of this disease?\n\n",
"How does an epidemic like this actually start? How come there are no cases for this for years and then all of a sudden it pops up? How does that first case come to arise? ",
"Why/how did those two americans taken out of africa to be treated in the US live, and why didn't the first victim diagnosed in america live?",
"Why are people confusing it with the black Plague?",
"What policies and procedures are in place for responding to infectious disease outbreaks of these sorts of diseases? Do local Health Departments just all of a sudden have a lot of extra work, is there some organized relief/assistance system in place?",
"At what point is containment essentially impossible? I assume there is a point, where it's just not feasible to stop its spread once a certain number of people have it. Even if you close all airports, public transportation, schools, etc. it will still continue to spread and there won't be enough medical facilities to deal with the number of patients.\n\nWhat is the number of patients where it's considered unstoppable? Maybe depends a bit on how geographically spread those patients are...",
"At what point does the global presence of the disease change it's status from \"epidemic\" to \"pandemic\"?\n\nSeeing as there are cases in at least 3 continents, does it require a finite number of cases, time, geographic dispersion, a combination of all 3 or is it something totally different?",
"How painful is Ebola compared to other terminal illnesses, and do our pain management solutions do a good job of dealing with that pain?",
"How susceptible are healthy people to the virus? If you're a healthy person, do you have a significantly lower risk of catching it than someone with a poor immune system if both were to come into contact with the virus?",
"We have all heard that Ebola is transmitted via bodily fluids, but most of the time this information also comes with people talking about blood, vomit, and feces of the patients. \nMy question is can Ebola be transmitted through sweat? Can someone with Ebola and with sweaty hands open a door and the next person who opens it be possibly contaminated?",
"Have we figured out why this outbreak has been so much more widespread than other ebola outbreaks? My understanding is that it is a generally slow spreading disease that burns bright but quick as it kills it's hosts so effectively and noticeably. ",
"At what point does it become a \"Pandemic\" as opposed to an \"Epidemic\"?",
"I know this is extremely unlikely, but I am generally curious about how to handle an outbreak, Ebola or whatever comes along next. Let's say it does end up spreading here. It wouldn't be all at once, first it would probably hit poor regions and works its way from state to state. At what point do I pull the kids out of school, stop going to work and just isolate ourselves from the rest of society? I wouldn't want to jump the gun too early but i also wouldn't want too wait to long. I live in the suburbs of a smaller city if that matters.",
"The mortality rate for Ebola where it is currently epidemic is around 50%. The dallas patient might have passed away from the disease, but I was wondering what we believe a 1st world health care system could do for mortality rates. \n\nIs there at least an educated guess as far as the survival rate would be for a first world case? ",
"Hi, I'm a grad student working on developing point-of-care diagnostics for infectious diseases, and I'm wondering if there are any conserved biomarkers that have been identified in the peripheral fluids of patients that could be targeted by ELISA-like rapid diagnostic tests (like a pregnancy test)?",
"America is taking steps to \"limit\" incoming travelers by giving them temperature readings at airports upon arrival if their starting location was from a high risk area. Is this really a way to catch this? If it takes 21 days to start showing symptoms and they've gotten on the plane with none of the symptoms, does this really seem like a viable solution? I feel like this is just a way to placate the public into thinking they're taking precautions. ",
"This has been bothering me for a bit, but could someone please explain to me the apparent discrepancies between all the statements, FB posts, etc about how there's 0 risk unless you've been directly exposed to their bodily fluids, and the fact that in Africa when someone tests positive they send in a hazmat team to completely and utterly disinfect all of their possessions and burn what they can't?\n\nThere was a post maybe a few weeks ago where a photographer followed a woman around after she got infected, and it seemed like a stark difference between \"bleach her entire house and burn anything that can't be disinfected\" and the statements from the government that seemed to say \"no we're not worried that someone might have gotten infected if he used a public toilet, and you're silly for thinking so.\"\n\nI'm sorry I can't quote specific examples, and most of it is just frustration at stupid condescending facebook posts of a simple flowchart saying \"no you don't have Ebola\" without citing any sources or anything, but I'm in Dallas and while I can understand all the facts and everything, and I go out of my way to ignore the fearmongering, it'd be hard to not have at least *some* small doubts, even if I wasn't worried about the aforementioned discrepancies.",
"I live in a major European city with direct flights from North Africa. This isn't really a science question (more of a political question) but why are governments hesitating so much to quarantine flights? Of course it's expensive and logistically complicated, but isn't it safer (and perhaps even cheaper) than the alternative (spread of the infection)? By the same token, why are governments flying aid workers home for treatment? This seems insanely risky to me compared to flying medical equipment down.",
"I had a guest speaker come in to one of my classes that said that the cdc predicts the total number of cases of Ebola to be 1,000,000 by the first of the year. At the current rate, how many cases until we reach the plateau? Will it continue to expand exponentially? ",
"I'm from Spain, and many of you would know that the virus is spreading here. There are at least 14 who are being investigated, and a woman which is certain that she has the virus (all of them are in the same hospital in Madrid). My question is: how fast the virus spreads? Thank you.",
"Viruses mutate. That's why there's always an updated flu vaccine each year, specific to each region, too. Since the Ebola virus is susceptible to mutation just as any other virus is, what are the odds of the virus mutating to the point in which it can be transferred without direct contact with bodily fluids? In other words, what is the probability of Ebola somehow mutating so it can infect others while airborne? This may seem like an irrational fear, but I would like to know if there is any sort of information about this.",
"While it seems clear that it would be difficult to imagine a large scale ebola outbreak in the developed world, how hard would it be for the virus to spark epidemics in \"middle class\" nations? I live in Uruguay and while its nice to hear that Europe is prepared, people here are quite nervous about our region's (Southern Cone) risk. ",
"The patient who died in Dallas was not given the antiviral serum developed from the surviving MD, due to the hospital stating the patient was out of treatment window.\n\n While I realize other antiviral medications have a time limit of effectiveness, the patient was admitted in hospital for 10 days before finally succumbing. This seems like plenty of time to at least attempt it's use?"
]
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| [
"http://www.reddit.com/r/askscience/comments/2isud7/what_would_happen_if_a_mosquito_bit_a_person/cl597qd",
"http://www.cdc.gov/vhf/ebola/index.html",
"http://www.reddit.com/r/IAmA/comments/2g79ip/i_work_for_doctors_without_borders_ask_me/",
"http://www.reddit.com/r/askscience/wiki/sources",
"https://www.reddit.com/r/askscience/comments/2bs08v/why_is_ebola_so_lethal_does_it_have_the_potential/",
"http://who.int/csr/disease/ebola/en/",
"http://www.reddit.com/r/askscience/comments/2ic301/with_all_this_fear_mongering_about_ebola_how/cl0uwlg",
"http://www.reddit.com/r/askscience/comments/2i51u1/cdc_and_health_departments_are_asserting_ebola/",
"http://www.reddit.com/r/science/comments/2hy3r9/science_ama_series_ask_your_questions_about_ebola/"
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16cahj | I few Warp Drive questions. | Here is a link to the website.
_URL_1_
Here is a link which got me interested from reddit.
_URL_0_
"White speculates that such a drive could result in "speeds" that could take a spacecraft to Alpha Centauri in a mere two weeks — even though the system is 4.3 light-years away."
Here is a few questions I have,
If you take a around trip vacation to Alpha Centauri that would be 8.6 light years. Would 8.6 light years pass on Earth while you spent 4 weeks in a "bubble"? Or would it just be 4 weeks?
Would this "bubble" create any G-force? Could the human body survive the trip moving that fast?
What about debris in space, asteroids, comets, plants, gases, stars?
Would we go through them because you're bending time and space?
Would we run into them?
Was not sure if I should tag this Astronomy or Physics.
EDIT: Links and Periods | askscience | http://www.reddit.com/r/askscience/comments/16cahj/i_few_warp_drive_questions/ | {
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"IIRC, there would be no significant time dilation using an Alcubierre metric because it is space itself moving. Inside the bubble the object has locally zero velocity, but I could be wrong. Therefore I think that only four weeks would pass. It also would not create any G-force since the spaceship is not being accelerated, space itself is moving. \nCan't answer the last question."
]
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| [
"http://www.reddit.com/tb/13tzcg",
"http://io9.com/5963263/how-nasa-will-build-its-very-first-warp-drive"
]
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[]
]
|
|
1n5owg | i've been diagnosed with tenitus (loud ringing in the ears) what's making my brain generate that noise? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1n5owg/eli5_ive_been_diagnosed_with_tenitus_loud_ringing/ | {
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"You didn't ask the person who diagnosed you?\n\nAlso, it's tinnitus.",
"I'm also suprised you didn't ask the diagnoser.\n\nThe brain is interpreting something and producing the ringing. There are several ways this can happen. Damage to the ear drum, damage to the hairs in the cochlea, damage to the nerves going to the hearing processing centers of the brain, damage of the processing centers themselves, damage to the small bones of the ears...\n\nBut it just is what it is now. I play music at night, seems to help. And zzzquil. OMG awesome stuff."
]
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[],
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7mfr15 | Why did Russian life expectancy drop massively in 1993? | I was looking at this graphic (Link #1 below), and noticed a significant lightening in Russia in 1993. So I found this paper (Link #2 below) and sure enough, from 1992 to 1993 the Russian male life expectancy dropped a fully three years from 62 to 59! And female nearly 2 years from 73.8 to 72. That's an enormous drop in one year and I've never seen or heard of anything like that.
Can anyone explain what exactly could cause such an enormous drop in one year? The article in link two talks about some potential causes, but I only somewhat understand it, not having expertise in the field, and I was wondering if I could get some understanding of the historical context of why/how this could have happened? Was this a reporting issue or a real massive drop in life expectancy in one year?
Link #1: _URL_1_
Link #2: _URL_0_ | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/7mfr15/why_did_russian_life_expectancy_drop_massively_in/ | {
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"Follow up: how reliable would pre-1993 numbers be? Would the Soviet Union fudge its statistics on a subject like this?",
"Broader question: what level of confidence do historians have in Soviet statistics? Is there a reason we might just think that the previous numbers were somehow deflated to look more favorable when presenting to leadership?",
"There was a [massive famine](_URL_1_). When Boris Yeltsin liberalized the economy in 1992, speculators came in and basically broke the Russian wholesale markets, causing massive price spikes. Inflation rose 2,500% in 1992. \n\nPreviously, the USSR had price controls for most foods, meat, dairy, wheat, etc. After prices were liberalized, the Russian diet shifted tremendously. People were unable to get, or afford, meat and diary products especially and only low-nutritive-value foods were widely available, i.e. potatoes and bread. \n\nAn additional issue wasn't just that food was too expensive, but that low quality substitutes came onto the market. Dangerous, toxic food substitutes. Poisoning and food-bourne illnesses were common. And mind you, this wasn't the healthiest population to begin with, as the old Soviet food systems weren't exactly renown for being particularly nutritious. \n\nAdd to all of this the end of subsidies to the Soviet health-care system and the end result is a huge swell in fatalities that continued on until the IMF helped Russia get on its economic feet in 1995, resulting in life expectancy rising agin in 1996. \n\n\nEdit: [Here's an interesting Rand Corp. paper on Russian mortality trends](_URL_0_). Interestingly, they pin a large number of deaths on excess alcohol consumption following the collapse of the Soviet empire. Wow.",
"I'll try and answer the best that I can, but it was a lot of reasons.\n\nCrime rapidly increases from 1991-1994.\n\nDue to the centralized collapse of the regime in the former USSR the Russian Mafia or small cliches called 'bandity' took over cities and towns all over Russia. The murder rates from 1993-1994 are one of the highest points of Russian crime rates in the Russian Federation. The police forces were either corrupted, understaffed, or ill-equipped or all above to deal with the large increase of gangs and mob rule over the major cities especially St. Petersburg which brings us to..\n\n\nThe Russian Drugs Crisis.\n\nCocaine, Opium, Cannabis, Heroin, and whatever there's a market for there's a demand for it and there was a huge demand for drugs. The borders collapsed, everyone can either leave the country very cheaply or simply walk out.. or come in easily. Drug trade exploded during this period because of the collapse of Border Guards and the reformation period of the military/police during this period means that it was impossible to secure or stop drugs from coming in from South America, Eurasia, etc, etc.\n\n\n\nThe older generation suffered the most.\n\nThe massive amount of smoking and drinking among the older population due to large stress of the collapse of the country from 1990-1994.\n\nThe older generation and those who didn't want to risk jail or death? Tobacco and alcohol use exploded after the collapse of the Soviet government meaning that once again more people died from car accidents, accidents, alcohol poisoning, cancer, etc, etc.\n\n\n\nHealthcare System utterly collapsed.\n\nHeart disease, heart attacks, strokes, and all kind of cardiovascular diseases killed off the middle to older generations of Russians in large amounts. Due to the stress, depression, sickness like the flu, and the unhealthy eating or lack of proper diet due to the collapsed of common good and services during this turmoil period and the medical services were just unable to give basic care to the older generations.\n\n\n\nFrozen conflicts\n\nRegions around Russia or where Russia is involved with such as the Chechen War for example saw a huge decrease in life expectancy because it was a war zone and the surrounding regions were suffering from large refugee, bandits, mob rule, corrupted arm forces on many sides. The list goes on and on.\n\nSources: _URL_0_\n\nJonathan Daniel Weiler (2004) - Human Rights in Russia: A Darker Side of Reform. Lynne Rienner Publishers. p. 36. ISBN 1-58826-279-0.\n\nAbraham Bob Hoogenboom (1997). Policing the Future. Martinus Nijhoff Publishers. p. 121. ISBN 90-411-0416-X.\n\nCrime in the Soviet Era Federal Research Division, Library of Congress\n\n\n"
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"https://gfycat.com/EmbarrassedFavorableCamel"
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"https://www.ncbi.nlm.nih.gov/pubmed/9508159"
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774jpx | What was the Communist Party of Korea like during the Japanese occupation, and how did Kim Il-Sung seize complete control over it after the establishment of North Korea? | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/774jpx/what_was_the_communist_party_of_korea_like_during/ | {
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"About a year ago i answered a [similar question](_URL_0_)."
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"https://www.reddit.com/r/AskHistorians/comments/4soti4/how_did_the_kim_family_obtain_power_in_north/d5bj5b2/?utm_content=permalink&utm_medium=front&utm_source=reddit&utm_name=AskHistorians"
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11c3gd | musical intervals (with emphasis on guitar) | I took elementary music theory in college, but it's been really hard for me to conceptualize the idea of understanding musical intervals and how they work.
Does anyone have a thorough understanding and can help me out? I'm not a dumb kid - I'm just not spacial AT ALL and need to see this stuff happening, or have it explained to me, to understand it.
(I've read stuff like this: _URL_0_ and I just get lost because I don't have a rote grasp of major/minor scales yet. I know how to derive them, but I can't seem to memorize them). | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/11c3gd/eli5_musical_intervals_with_emphasis_on_guitar/ | {
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"The simplest way to describe an interval is that it's the number of semitones between two notes. There are 12 semitones in an octave and each one has a special name. Here's what that would look like using a C chromatic scale:\n\n* 12. Octave (C)\n* 11. Major 7th (B)\n* 10. Minor 7th (Bb)\n* 9. Major 6th (A)\n* 8. Minor 6th (Ab)\n* 7. Perfect 5th (G)\n* 6. Tritone (Gb)\n* 5. Perfect 4th (F)\n* 4. Major 3rd (E)\n* 3. Minor 3rd (Eb)\n* 2. Major 2nd (D)\n* 1. Minor 2nd (Db)\n* 0. Root (C)\n\nYou might notice that the intervals labelled \"major\" match up with the notes of the major scale, and the ones labelled \"minor\" are in the minor scale (except for the minor 2nd, which gets no love). The perfect intervals are the most harmonious intervals, and appear in both scales, while the \"tritone\" is a special interval that is extremely dissonant and is in neither scale. For intervals larger than an octave, the cycle repeats again (starting with minor 9th because the octave is the 8th note).\n\nEDIT: Since you asked for an emphasis on guitar, I made you [this diagram](_URL_0_) as an illustration. If you're playing in C (root note 3rd fret on A), the number on the diagram matches up with the interval on the list."
]
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| [
"http://audio.tutsplus.com/tutorials/music-theory/music-theory-intervals-and-how-to-derive-them/"
]
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[
"http://imgur.com/CLQhw"
]
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4y3laa | when people that are lactose intolerant eat or drink dairy, what exactly is happening inside their stomach when diarrhea occurs? | [deleted] | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/4y3laa/eli5_when_people_that_are_lactose_intolerant_eat/ | {
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"So lactose intolerance happens when someone's body does not create enough [lactase](_URL_1_). Lactase is an [enzyme](_URL_4_) that would break down [lactose](_URL_3_), the unique sugar component of milk, into sugar that our bodies can use for energy. Lactose intolerant people have issues with breaking down the lactose in their small intestines, which is a part of the digestive tract after the stomach that is responsible for absorbing a great amount of the nutritional stuff that goes through our body. So when a lactose passes through the small intestine and into the large intestine it removes water from the colon lining (through [osmosis](_URL_0_?)) and causes excessive runny poops. Much of the more complicated answer involves [microbial communities](_URL_2_).\n\nEdit: added a bunch of links in case you get carried away with this question and want to learn more but appreciate quick links. Additionally, did you know in some Asian communities over 90% of individuals experience some level of lactose intolerance? This fun fact also brings up the important distinction that not all lactose intolerance is equal. ",
"extra credit: why/how is it possible to overcome this allergy over time? "
]
} | []
| []
| [
[
"https://www.reddit.com/r/explainlikeimfive/comments/j2egm/can_someone_please_explain_osmosis/",
"https://en.wikipedia.org/wiki/Lactase",
"http://www.medicinenet.com/lactose_intolerance/page2.htm",
"https://en.wikipedia.org/wiki/Lactose",
"https://en.wikipedia.org/wiki/Enzyme"
],
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3zvlf7 | is modern industry able to make cheap paper not from wood? | E.g. from synthetic polymers. Surely, if they are not made from wood themselves :)
If not, what are main bottlenecks? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/3zvlf7/eli5_is_modern_industry_able_to_make_cheap_paper/ | {
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"Paper gets made from fibres such as linen, too, and a lot of paper is recycled. It would come down to cost, whether synthetic polymers would do the job and be cost-effective (i.e. cheaper).\n\nTyvek® has many of the properties of paper - e.g, it's flexible and you can write on it - but it's more expensive. ",
"The question is though... What's wrong with paper from wood? The paper industry plants as many trees as they cut down nowadays, to make sure they will be able to still make paper in the future. It's not like massive forests are disappearing because of paper.",
"Even if we could make paper cheaper, faster, and better from synthetic sources, we may not want to. Paper is biodegradable, recyclable, and comes from an infinitely renewable source (trees and other plants). The most likely alt would be some sort of petroleum product, which is non-renewable and often non-biodegradable.",
"Really there just isn't a good alternative that's biodegradable and cheap. Also can't believe no one has commented talking about hemp paper haha"
]
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2pqlq3 | how hard would it be to just unplug all of n. korea from the internet? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2pqlq3/eli5_how_hard_would_it_be_to_just_unplug_all_of_n/ | {
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"Not that hard but China's assistance would be a prerequisite. But that goes against all ethical reasoning in that the internet should be available to all.\n\nEven if you did, the chances are that the Sony hack was conducted from outside N. Korea. ",
"Technically easy, they're decades behind in infrastructure, and I doubt they have many trunk lines or much redundancy. I'd actually be surprised if they had more than one or two physical lines. Blocking satellite access would be a lot harder, of course.\n\nBut it wouldn't have the effect you want, because it won't stop them from \"hacking\" sony or whatever they feel like next time. It's pretty likely that attack wasn't even done from within north korea, and virtually certain they relied on non koreans anyways.",
"It's pretty hard to unplug a country that doesn't have electricity. North Korea's hackers work all over the world to cover their tracks and utilize free wifi hotspots that they don't have in Pyongyang."
]
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2cn679 | why do analog tv broadcasts still exist in the us? | I thought all US TV broad casts were required to be digital for some time now.
Doing a channel scan on my TV just today it ended up detecting 3 analog stations along side all the digital ones. The analog ones were all fairly weak and all spanish television.
Isn't it an FCC requirement any TV broad cast be digital? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2cn679/eli5_why_do_analog_tv_broadcasts_still_exist_in/ | {
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"text": [
"Low Power TV stations are still allowed to transmit in analog in the United States. The current deadline for them to convert to digital is Sept 1, 2015.\n\n_URL_0_"
]
} | []
| []
| [
[
"http://www.fcc.gov/guides/low-power-television-lptv-service"
]
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3ml8nj | Do modern high heels worn by women and Chinese foot binding have any historical similarities in the way they developed? | I know foot binding developed in the 7th century and became popular during the Song Dynasty. What I'd like to know is if high heels in the western sense also developed as a less harmful but ideologically similar equivalent of the bound feet "three inch lotus." Were high heels popular because of the perceived additional attraction they provided to women, even though they're harmful to the feet, or did they develop in another fashion and became popular another way? As I understand it, foot binding came into being when a Chinese ruler during the 5 states period got a woman to dance with small bound feet to dance on a platform, and then all the court women followed her example. Are there any other similar myths on how high heels came about? Was it primarily as a response to their aesthetic value that high heels became a sign of beauty for women or did its usage evolve in other ways? | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/3ml8nj/do_modern_high_heels_worn_by_women_and_chinese/ | {
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"No, not really.\n\nIn western Europe, high heels date back to the 17th century for both men and women, and were worn by fashionable men and women into the 18th century. There is no clear origin, only speculation and apocryphal stories (so in that sense, there *is* a connection between foot-binding and high heels), such as the idea that various rulers invented or popularized them in order to be taller than their subjects. Louis XIV and Catherine de' Medici both come in for this - Catherine de' Medici is also falsely but commonly stated to have forced her court ladies to tightlace to a 13\" waist, so there is possibly some correlation between the stories, a long-running reputation for fetishism in dress? A more likely origin is that the heel was brought from Persia and found to be helpful on riding boots, to better hold the stirrup, and then was applied to more and more non-riding footwear.\n\nIn Venice and Spain, during the 16th century, there was a woman's shoe called the *chopine* that comes closer to bound feet in ideology. These are sometimes considered proto-high-heels, but I think this is because of an assumed ideological similarity - they're actually tall platforms. The Metropolitan Museum of Art has [a nice little page on them](_URL_2_). We used to think they were associated with prostitutes, and therefore about sexuality mixed with helplessness (that assumed similarity I mentioned), but we now know that they were worn by noblewomen as well. [Here's another good resource.](_URL_0_)\n\nThe thing to remember is that \"high heel\" before the 1930s or 1940s really does not mean what we think of when it comes to high heels. An inch or two at most is generally what was worn. Not anywhere near as incapacitating as modern stilettos, let alone foot-binding. \n\nA curator at the Bata Shoe Museum recentlyish wrote a book, *Heights of Fashion: A History of the Elevated Shoe*, that might be interesting to you. She attributes men's abandonment of high heels over the early 18th century to Enlightenment ideas about men being more rational than women, and men's clothing becoming more sober and \"unfeminine\" is a narrative that plays out over the course of the century. Still, [men's heels were still kind of clinging on in the 1780s](_URL_1_).",
"There a few previous questions of similar nature with good discussions on how the heeled shoe came to be created:\n\n[Heeled Shoes](_URL_0_) and [When was the High Heeled Shoe invented?](_URL_1_).\n\nWhile the heeled shoe today is associated with women and with foot pain, it was not originally the case. Both men and women were wearing heels at certain times, men's use falling out during the 18th century. Women's fashionable heel heights have gone up and down in the decades since. Various heel heights and styles have always been available as well, not restricting the woman to only one extreme. In the 1770s you can find mentions of French, English, Italian, Low, and Common heels in advertisements. Just like today in our shops you'll find flats, wedges, stilettos, kittens, Italian, and many more. Women today certainly do wear higher heels due to the perceived notion that it is more attractive (longer legs, re-alignment of the spine that moves the hips back, etc) and likely that plays a part in many other time periods as well, but that was not why they were created."
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"https://www.pinterest.com/pin/228065168599541705/",
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6e0vho | Photon Energy Levels, what is different about Radio wave photons vs Gamma wave photons? | So I know gamma is the high energy end of the EMS and radio is low, but what exactly is that extra energy coming from? They aren't going faster (still light speed) and they aren't more massive (still a photon) so what is it that gives certain frequencies this extra energy? Am I confusing force for energy? Does it have to do with the spin?
I know electron volts are how the energy is measured, but I still don't really get how this relates to the photons themselves. | askscience | https://www.reddit.com/r/askscience/comments/6e0vho/photon_energy_levels_what_is_different_about/ | {
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" > but what exactly is that extra energy coming from?\n\nWhatever is producing the photon.",
" > so what is it that gives certain frequencies this extra energy?\n\nIntuitively, a wave that is waving more rapidly will be more energetic. Thus higher frequency v means more energy E, directly seen in Einstein's relation E = hv.\n\n > I know electron volts are how the energy is measured, but I still don't really get how this relates to the photons themselves.\n\nThe electron volt is just a unit of energy, like the joule. It's equal to the kinetic energy an electron gains while moving between a potential difference of 1 volt."
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k2u38 | Partial pressure of O2/CO2 in blood versus the actual concentrations of O2/CO2 exchanged; why the huge difference? | I'm having a hard time understanding these numbers:
o Blood before lungs
+ PO2 = 40 mm Hg
+ PCO2 = 45 mm Hg
o Blood after lungs
+ PO2 = 100 mm Hg
+ PCO2 = 40 mm Hg
I know that the actual concentrations of O2/CO2 exchange are about 1:1, around 5ml, but what accounts for the drastic change in O2 partial pressure? How can the same concentrations of two different gases give different partial pressures?
I'm guessing the reason is in how these are transported, but how does O2, which is mostly bound to hemoglobin 4 at a time, result in higher partial pressure than CO2 that is just dissolved?
*This is not a homework question, I don't even get homework. I just want to understand this beyond memorization. Thanks
| askscience | http://www.reddit.com/r/askscience/comments/k2u38/partial_pressure_of_o2co2_in_blood_versus_the/ | {
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"I'm not sure if i'm qualified to help you, as i have troubles understanding your doubts.\n\nBut did you take into account that solubilized CO2 is in equilibration with HCO_3^- / H_2CO_3?",
"Well, you partially answered your own question; oxygen pressure increases dramatically due to hemoglobin binding. Some oxygen is directly dissolved into the blood, but this amount is almost negligible compared to that bound to hemoglobin. CO2, on the other hand, is mostly present in the blood in the form of bicarbonate ions, and this conversion and excretion process is slower than oxygen transfer to hemoglobin. Oh, and relative pressures of inhaled air is important too. \n\nOxygen transfer in the lungs is normally perfusion limited, meaning that the amount of oxygen transferred from air to blood is limited by the rate of blood flowing through the lungs. This is because oxygen transfers very well to the blood, faster than blood can flow through the lungs. ",
"I'm not sure if i'm qualified to help you, as i have troubles understanding your doubts.\n\nBut did you take into account that solubilized CO2 is in equilibration with HCO_3^- / H_2CO_3?",
"Well, you partially answered your own question; oxygen pressure increases dramatically due to hemoglobin binding. Some oxygen is directly dissolved into the blood, but this amount is almost negligible compared to that bound to hemoglobin. CO2, on the other hand, is mostly present in the blood in the form of bicarbonate ions, and this conversion and excretion process is slower than oxygen transfer to hemoglobin. Oh, and relative pressures of inhaled air is important too. \n\nOxygen transfer in the lungs is normally perfusion limited, meaning that the amount of oxygen transferred from air to blood is limited by the rate of blood flowing through the lungs. This is because oxygen transfers very well to the blood, faster than blood can flow through the lungs. "
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4touns | how do single cylinder engines work? | . | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/4touns/eli5_how_do_single_cylinder_engines_work/ | {
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"When the piston goes up into the cylinder, it squeezes a fuel-air combination, and when it gets to a \"sweet\" spot, the spark plug at the top of the cylinder fires, igniting (somewhat explosively) the compressed fuel-air mix. This drives the cylinder down. \nA rod on the bottom of the piston is non-rigidly attached to a drive shaft. The rod is allowed to move back and forth as well as up and down as it drives the shaft. When it gets to the bottom, the shaft keeps on spinning, and moves the rod a little more in the direction it had been traveling. As the shaft continues its rotation, this pushes the piston back up into the cylinder again to start the whole deal over again. ",
"A single-cylinder engine works just the same as other engines; you compress a working fluid with oxidizer in it (i.e. air), and add fuel which then combusts, raising the pressure and temperature of the working fluid in the cylinder to high levels. You then take advantage of that high pressure to drive a piston downwards, which is connected to an output shaft that can be used to drive something. In the cylinder, after expansion, the exhaust gas is expelled, and new fresh air enters the cylinder to prepare for the next round of combustion. Suck, squeeze, bang, blow, with all 4 steps repeating dozens to hundreds of times every second.\n\nThe only difference with multiple cylinders is that they work together on the same output shaft.",
"All engines have a flywheel of some sort to smooth out their power output. In a four-stroke engine with less than four cylinders or a two-stroke engine with only one, the flywheel's inertia is the only thing turning the engine when there isn't a power stroke occurring in one of the cylinders.",
"I assume you have a basic understanding of cylinders, so I'm just going to answer the single cylinder question with a very simple example:\n\nImagine those elliptical machines at the gym. They actually function pretty similar to cylinders. You can just use one leg if you time your pushes correctly. Here is an example: _URL_0_"
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1jwulh | Did the Roman economy suffer through "Bust and Boom" cycles? | And, if so, what did they do when they found themselves in a 'bust?' What might have caused economic crashes? | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/1jwulh/did_the_roman_economy_suffer_through_bust_and/ | {
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"This is a very interesting question that I would like answered (as well as the spam deleted). Did the slave economy more or less function in a stable pattern of growth fueled by conquests until the decline brought about stagnation? Or were there boom and bust cycles as in the capitalist system? Any experts care to weigh in?",
"It is quite difficult to tell. The modern boom-and-bust cycle is based on a liquidity of economic assets and market integration that were simply impossible in a premodern world. The Roman economy was remarkably well integrated for a premodern economy, but if Ephesus sneezed Autun would not catch a cold.\n\nIt is possible to see localized, for lack of a better term, periods of differential economic performance, such as Pompeii, which boomed during the Augustan period and declined in the late Julio-Claudian. But as DeSoulis noted, this was not a matter of boom and bust so much because the timeframe is far too long. There would also be years of bountiful harvest and years of famine, which would have potentially had a similar effect as boom and bust cycles on the individual, but again isn't quite what you mean.\n\nThe caveat of course is that we don't have the evidence to make such granular analysis--as a comparison, someone doing archaeology on nineteenth century America in a thousand years would see continuous economic development and not the busts. But current economic understanding would argue against.",
"**IMPORTANT NOTE: the Roman economy is a very difficult subject to truly understand, since we lack a lot of evidence for economic conditions in ancient times. The period I discuss here is particularly bad, since there are almost no contemporary sources from the crisis of the 3rd century. We're still discovering new emperors about whom we had no prior evidence because one of their coins turns up on a dig. Keep that in mind throughout this post.**\n\nI don't know about boom and bust cycles in the modern sense of the term, but there were certainly major economic crises, usually relating to currency. (Remember, Rome lacked fiat currency; all currency depended, in theory, on the value of gold)\n\nFrom the time of the Republic through the 2nd century, Rome experienced tremendous economic prosperity. The economy was largely based on agriculture, which was a successful industry, especially given the new agricultural land gained in conquest and the influx of foreign slaves from the newly conquered peoples. When Rome began to conquer the areas along the Eastern Mediterranean, this brought in so much wealth that many authors began to criticize the decadence of their age. (cf. Propertius and Tibullus, for a few examples) There were some issues with smaller landowners being dispossessed by larger farms, called *latifundia*, but this was really the only main economic issue, and didn't cause a depression.\n\nOne of the best examples of a \"bust\" is the Crisis of the Third Century, which was a major political, military, and economic crisis that lasted for decades. At this time, there was tremendous instability, with each emperor lasting for only ~2 years or so (IIRC, the average reign of an emperor from the assassination of Alexander Severus in 235 to the accession of Diocletian in 284 was 1.5 years). The vast majority of emperors were killed; only 2 or 3 died natural deaths. Alongside this political crisis, the economy sank into a depression. Trade slowed down, and there was hyperinflation of the currency (often, this happened by stating that a coin had a certain value, while debasing its actual value by adding in lesser metals). It should be noted that debasing the currency started long before the Crisis of the Third Century; it just reached its lowest point then.\n\nBy the time Diocletian became emperor, the currency was so debased that it was practically worthless. Diocletian came in with his Edict on Maximum Prices (301) to combat inflation. This set maximum prices on a long list of goods and services to prevent inflation. It also declared the value of certain coins, and set them at a certain rate against the value of gold. Resisting the Edict was, in theory, punishable by death; however, it was still ineffective, and many people sold goods at higher prices. In addition, the number of new coins Diocletian minted contributed to inflation even more.\n\nUltimately, Rome only got out of this crisis during the reign of Constantine, who established the gold solidus as the primary currency. One of the main reasons he was able to achieve this was because of his confiscation of the treasures of pagan temples.\n\nAfter the reign of Constantine, the economy may have stabilized for the rest of the 4th century. However, this is currently a point of dispute. The traditional narrative holds that the decline of the 3rd century continued throughout the 4th; newer archaeological evidence suggests that rural areas were very successful economically, and certain provinces, like North Africa, flourished, while there may have been decline in other areas.\n\nLater on, in the 5th century, prior to the fall of the Western Empire, there was another economic crisis, this time not related to currency, but to invading barbarians. The invasions of the Goths et al. in the early 5th century lead to a decline in agricultural output, which lead to a decreased tax base, and then a smaller military, which was less able to defend against future invaders. It became a vicious cycle like this until Rome fell.\n\nSource: A class I took on Late Antiquity, and Bryan Ward-Perkins' *The Fall of Rome: and The End of Civilization,* among others."
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1sycin | why at rock concerts and gigs is it always impossible to get the sound of the vocals to sound clear over the rest of the band? | I was in a band or two when I was younger and never once did a gig where the vocals were clear, even with decent P.A. systems. Even at professional concerts i.e. Frank Ocean, a lot of songs I found I couldn't hear the vocals clearly over the instrumentals. | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1sycin/eli5_why_at_rock_concerts_and_gigs_is_it_always/ | {
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"A public address system system is not a sound system. A professional sound engineer makes all the difference.",
"It's all about the sound engineer and the equipment they use. A shitty engineer won't get it right but the good ones will. Also depends where you are sitting/standing. ",
"the human voice is a really difficult thing to capture. Unlike instruments, it doesnt have a definite frequency or volume. This means a sound engineer has to constantly be adjusting the mix to bring the vocals out. They try to combat it with compression to regulate the volume, but it still shifts frequency, and gets muddied with the other instruments.",
"Three reasons. First, the guitars are always up too damn loud. Second, many smaller venues don't have adequate systems because that costs money. Third, many sound guys don't really care about their jobs in smaller places. Believe me, when you find a small venue with an adequate system and an engineer who cares, you can tell pretty quickly. "
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1xqrgk | why should we care that we created nuclear fusion? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1xqrgk/eli5_why_should_we_care_that_we_created_nuclear/ | {
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"As you might know, most of our energy comes from unsustainable and highly polluting fossil fuels. Wind, solar, hydro, and geothermal sources can't create enough energy to replace them. Nuclear fission power plants produce highly radioactive waste. So we need some large source of energy that has a readily available fuel, doesn't pollute, and can produce enough energy to sustain a developing world. One of the most likely sources is through nuclear fusion. The fuel is not too uncommon (it can be found in sea water), it doesn't leave radioactive waste like fission, and it can theoretically produce large amounts of energy. We have some technological hurdles to sustain the process and for it to generate more power than it consumes, but many scientists and engineers are confident that some time decades from now, it can effectively eliminate many of today's problems with generating energy."
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496dte | how is pre-made frozen food at the grocery store less healthy than food you make yourself and then refrigerate? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/496dte/eli5how_is_premade_frozen_food_at_the_grocery/ | {
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"It's not. However, making it yourself allows you to use healthier ingredients and actually choose what you eat.",
"It's not *necessarily* less healthy, depending on what you make at home. But, generally speaking, pre-made foods are often made with more salt, sugar, and/or fat than people usually use when they make their own food.",
"Generally, frozen, premade foods are made from ingredients that are processed. Processed foods, generally speaking, are shelf stabilized for longer shelf life and that means there are usually loaded with preservatives, which are not healthy. There are premade, frozen foods that are made with better ingredients. Just read the labels to find the better foods. If there are ingredients you can't pronounce, then you are looking at chemically stabilized foods. Those are the ones you should avoid. \n\nPremade foods like fried checken are one of the foods that are not necessarily unhealthy, unless they are actually fried instead of baked.\n\n",
"Some of those premade frozen meals have like 40% or more of the daily recommended amount of sodium. "
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1n9g9u | What do social and political sciences say about when we will get to dealing with global climate change? | I'm curious to know if there has been systematic study of when communities deal with threats with the characteristics of climate change. I realize that there may have been few threats as sweeping, global and gradual as CC in the past but it seems to me the prisoner's dilemma characteristics, threat to poor greater than rich, actions of one country impacting the health of others, etc. might be similar to the attack of some horde, the desertification of smaller areas or some other major change. I'm most interested in how long it takes for to get society moving on things and what causes it.
Observations about the elements which drive such decisions would be interesting too though I'd expect they are simply patterns of individual profit vs. societal good and ongoing political inertia. I'm not expecting to get 'the third Tuesday in December everyone will get off their rear and leap into action' but 'nothing really happens until a series of major related events combined with a lack of nonrelated crisises' might be interesting to know about. | askscience | http://www.reddit.com/r/askscience/comments/1n9g9u/what_do_social_and_political_sciences_say_about/ | {
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"You might want to have a mod change the the category flag for this question, as it's pretty far afield of the physical science of climate change. Poli sci, economics, or another social science might be more appropriate. \n\nIn the mean time, I can toss you some leads that I've stumbled across until someone else can do better. \n\nIn terms of: \n\n > it seems to me the prisoner's dilemma characteristics, threat to poor greater than rich, actions of one country impacting the health of others\n\nYou might be interested in: \n\n* [The Global Deal: Climate Change and the Creation of a New Era of Progress and Prosperity](_URL_3_) (Stern, 2009)\n\n* [A Question of Balance: Weighing the Options on Global Warming Policies](_URL_2_) (Nordhaus, 2008)\n\n* [Combined inequality in wealth and risk leads to disaster in the climate change game](_URL_1_) (Burton-Chellew, et al., 2013)\n\n* [Circumspection, reciprocity, and optimal carbon prices](_URL_7_) (Kopp and Migone, 2013)\n\nThe most recent crisis on a scale remotely like anthropogenic climate change was arguably ozone depletion. There are some missteps one can make in believing that these are 1:1 fits for each other, but there are certainly valuable lessons to we can learn about intergovernmental diplomacy, scientific consensus informing policy, projected vs. realized costs of action, etc. These are some accounts of how we avoided a pretty serious catastrophe through a mix of science, advocacy, governmental action, technological innovation, etc.: \n\n* [Protecting the Ozone Layer: Science and Strategy](_URL_0_;) by Parson\n\n* [Ozone Diplomacy: New Directions in Safeguarding the Planet](_URL_5_) by Benedick\n\n* [Ozone Discourse: Science and Politics in Global Environmental Cooperation](_URL_6_) by Liftin\n\nThere is a long history of industry funded (and ideologically metastasized) denial of health/environmental problems, fear-mongering about the economic consequences of action, claims that the problems are intractable, etc. A brief summary of the history of this dynamic is:\n\n* [Merchants of Doubt: How a Handful of Scientists Obscured the Truth on Issues from Tobacco Smoke to Global Warming](_URL_4_) (Oreskes and Conway, 2010)"
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"http://global.oup.com/academic/product/protecting-the-ozone-layer-9780195155495;jsessionid=CF0AFA00B370ED122FB7E0F5A7B9DC39?cc=us&lang=en&",
"http://link.springer.com/article/10.1007/s10584-013-0856-7",
"http://www.amazon.com/Question-Balance-Weighing-Options-Policies/dp/0300137486",
"http://www.amazon.com/Global-Deal-Creation-Progress-Prosperity/dp/1586486691/",
"http://www.amazon.com/Merchants-Doubt-Handful-Scientists-Obscured/dp/1596916109/",
"http://www.hup.harvard.edu/catalog.php?isbn=9780674650039",
"https://cup.columbia.edu/book/978-0-231-08137-5/ozone-discourse",
"http://link.springer.com/article/10.1007/s10584-013-0858-5"
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24qhyw | how do satellites orbiting the earth get their orbits assigned to them, and how do they not hit into each other? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/24qhyw/eli5_how_do_satellites_orbiting_the_earth_get/ | {
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"Space agencies coordinate data on the tracking of the debris field above earth, to help avoid any sizable objects.\n\nBut mostly, the odds are just very low that you will hit anything. The surface of the earth is a big place, and the stuff we put into orbit, with a few exceptions, is relatively tiny. Picture a dust mote circling a beach ball.",
"I don't know about the orbit assigning part... but in my experience (at least with KSP) space is HUMONGOUS! You really have to try to get 2 objects even relatively close enough to each, and getting them close enough to actually hit is a miracle. Personally, it's not the satellites that pose a threat. A satellite is a single piece of machinery placed in orbit by people who know what they're doing (at least one would hope so). The most likely thing you would have to worry about in space in terms of collision is the thousands of pieces of debris from broken space junk/ejected pieces of rockets.",
"Much like how planets in our solar system orbit faster around the Sun when they are closer to the sun, satellites differ in orbit speed when placed at different attitudes from Earth.\n\nIf satellites are orbiting at different speeds only if they are at different altitudes. Since they are at different altitudes, they won't collide.\n\nTwo satellites placed in the same orbit attitude will orbit at the same speed. Since they never speed up or slow down normally, there is no chance of them hitting each other unless some other force acts on them.",
"Spent the last 25 years in the space business. It depends on the orbit. Geostationary communication satellites have their slots (e.g. longitude) assigned by the International Telecommunications Union (ITU) _URL_3_. If I want to put up a new comm sat I have to file with my national regulatory agency (for the US this is the Federal Communications Commission). The FCC then works with the ITU which may award a slot. The spacing is determined based on the type of communication service you want to offer and frequency you will be operating in. If satellites operating on the same frequencies get too close in longitude then they will cause interference into each others ground terminals (e.g. dishes). But two satellites at different frequencies can be in the same slot. Several geostationary operators operate multiple satellites in the same slot (most famously SES Astra having 6 in one slot _URL_1_). \n\nFor non-geo satellites, it's pretty much not an issue. Space is big and satellites are not. Until they do hit, such as the famous Iridium/Cosmos collision in 2009 _URL_2_.\n\nThe US Air Force Joint Space Operations Center (JSpOC) _URL_0_ does monitor all the objects in space and checks for potential collisions and notifies operators of potential collisions. Due to the limited accuracy of the orbital data it's difficult to predict with any certainty that an actual collision will occur, at best you can calculate a probability (usually around 1E-6 or smaller). \n",
"Space is big. Really big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space."
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9b0kgz | what's the difference between allegory and metaphor? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/9b0kgz/eli5_whats_the_difference_between_allegory_and/ | {
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"The short version: An allegory is a type of metaphor.\n\n \nLonger version: A metaphor is a figure of speech that substitutes in a non-literal alternative to make an interesting point. Saying that \"his heart is a shattered vase\" is a metaphor, because a heart is definitely not a balloon, but it gives you an interesting image about how heartbroken that guy is. But it's not an allegory.\n\n \nAn allegory is specifically a story, poem, or image where the characters, places, or events are used as metaphors to make another point. So it's a little more fleshed out than the metaphor overhead. The Narnia books are seen to be allegorical, showing the foundations of Christianity (the creation of the world, a savior figure, a Last Judgement) in the form of a story about a magical world with talking lions and evil witches. Plato's Allegory of the Cave is about human understanding and learning, with humans trapped in a metaphorical cave staring at shadows on the wall, unable to understand what the greater world looks like when it's explained to them by someone who understands it better than them.\n\n & #x200B;\n\nSo an allegory is sort of a metaphor on a larger scale, while a metaphor can be small or large, not needing the structure of a larger work of art to be understood."
]
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[]
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|
||
fkkxz | Biologists: Snake repellent? | First let me thank you in advance and give you some background. I live in a tropical island in Brazil and had my new house built 1 year ago. When I moved back then I had 3 encounters with Coral snakes and that freaked me out. I suppose it was because we had lots of dirt being moved around but I was lucky to have workers with steel balls to take care of them.
So now summer is back and so are the damn snakes. Corals are fairly docile but I have 6 dogs and they looove to hunt geckos, bugs and the eventual toads and bring it to me as gifts. Yesterday one of the dogs brought me a small-ish coral snake (still alive).
To make it worse, they bring their findings to my bed. So you have an idea why I fear for my safety and that of my dogs.
So I ask you: How do I keep these satan spawns out of my yard?
Understand that:
- It is summer and rain season.
- I keep the grass trimmed and there's nowhere to hide (wood, rocks, bushes).
- I can't just lock myself and the dogs in. I want to enjoy the pool in the 40ºC+ days and let the dogs out to exercise and pee/poo.
- Interrupting its food source is difficult. Bug sprays are useless with so much rain and being an island the rat population is above average. While not a big issue, I can't use rat poison because of the dogs.
- There are many unkept lots for sale around and I can't do anything about it.
- There is no commercial snake repellent solution available anywhere here.
So I ask you:
- How do I get them off my lawn (besides a moat full of acid)?
- From what I read they nest underground. True?
- Are mothballs effective or just a myth? And garlic?
- Should I just kill or release them far from my house? Will they come back? I like to think they exist for a good reason but again their poison is very toxic.
- Welp! | askscience | http://www.reddit.com/r/askscience/comments/fkkxz/biologists_snake_repellent/ | {
"a_id": [
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"text": [
"Plant lemongrass.\n\nOr get a pet mongoose.",
"Cats will reduce the rodent population. I live in Rural California and we have a lot of Rattlesnakes, we have cats to bring down the rodent population, lessening the snakes. We still find them, but when we do they meet Mr. Shovel. "
]
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[],
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|
47muw7 | why do ants drop other ants off ledges? | Background info: My college has a bad ant problem upstairs.
I was sitting down watching the ants walk along the window sill, and noticed one was carrying another one that had wings toward the edge. The ant then proceeds to throw the ant with wings over the edge of the window sill- at least 3.5 feet to the floor, then walk away. Why would he have been thrown over the edge? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/47muw7/eli5_why_do_ants_drop_other_ants_off_ledges/ | {
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"Not sure if the carried ant was alive, but as i'm aware ants will remove ant-corpses from the vicinity of their colony so disease doesn't spread and doesn't attract predators. Perhaps that's why? ",
"Was it possibly a drone ant they was no longer needed? Once the Queen has done her thing the guys get tossed."
]
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[],
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8chk2l | why have we developed to sometimes hold our breath during tense situations? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/8chk2l/eli5_why_have_we_developed_to_sometimes_hold_our/ | {
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"Put simply, your brain puts all it's resources to getting you out of that situation, including the bit that controls your subconscious breathing",
"I'm going to do my best here. Deep breathing activates certain neurons in the brain that tell your body to relax. Holding your breath heightens that response a little. It also provides proprioceptive input, meaning it activates your muscles through that feeling of tension in your chest/abdomin. Similar to swaddling a baby, putting a thunder vest on a dog, or how a nice good hug is calming. ",
"I always assumed it was to better avoid predators and allow us to listen more carefully. This thread has been enlightening."
]
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[],
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|
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1y0jvh | What were the reactions and perceptions of new allied technology by the axis? | We hear a lot about how we reacted to jets and rockets, but what of the opposite? | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/1y0jvh/what_were_the_reactions_and_perceptions_of_new/ | {
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"text": [
"It's worth noting that most of the major Allied technologies we associate with the European war were secret (e.g. the code-breaking computers) or subtle. The most important two were probably radar and the proximity fuze. Neither of them have a \"Wunderwaffen\" quality to them. The Germans had their own proximity fuzes (though they didn't deploy them as heavily), they had their own radar (though they didn't develop them as well or integrate them as successfully into their total defensive and offensive plans). The Allies also used napalm to deadly effect — again, not much of a wonder weapon, just a good improvement on existing techniques (incendiary bombs). I am wracking my brain for a good Allied technology that mattered during World War II that would have actually been a significant propaganda tool, or made a big morale splash, and just not coming up with any. The German technologies were superficially impressive but ended up being not very effective militarily in the forms developable for the war. The Nazis led the \"super technology propaganda\" war during the war itself even though the Allied technologies, while superficially more banal, were much, much more useful for winning the actual war.\n\nThe atomic bomb, of course, would qualify as a wonder weapon but, of course, it was not developed in time for use during the European campaign. The physicists who were working on fission work for the Germans were justifiably shocked that the Americans had managed to pull that one off, when they heard about it after Hiroshima."
]
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[]
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7wlq24 | why do surgeons need to wash their hands for an extend period of time when normal sanitizer already kill 99.9% of all bacteria | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/7wlq24/eli5_why_do_surgeons_need_to_wash_their_hands_for/ | {
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"I believe it's usually to make sure they've got every last part of their hand. Between their fingers, under their nails etc. ",
"Most people don't thoroughly wash their hands, even when using hand sanitizer. Surgeons take their time to ensure that every nook and cranny is washed. ",
"From what I understand, sanitizer kills the organisms, but those dead \"corpses\" are all still there. The body reacts the same way to a dead virus as it does to a live one. Washing probably cleans all that dead stuff off too.",
"Sanitized dirt and feces and food are still dirt and feces and food. Stick any of those into a surgical site, the body will attack it. \n\nThen:\n\nImagine taking a steak and a bucket of white paint. Red is dirty, white is sanitized. Paint the steak. No matter how well you paint, if you bend or fold that steak enough times, you’ll eventually see more red.",
"I always thought that part of the length of the wash was drilling a routine into your head so you wash every nook and cranny of the hand (between fingers and such). I imagine that if someone wanted to there could be a cleaner or some sort of santizer (either soap or machine or both)) that could do things faster but would you really want a surgeon to do something fast or do something thoroughly?",
"The 99.9% comes from \"ideal usage\", not real world usage. Ideal usage looks a lot more like what surgeons do than what you do in the lobby of the DMV.\n\n99.9% is not enough, for surgery.\n\n99.9 applies to some types of germs. Again, 'some types' is not enough for surgery.",
"Antibacterial hand soap only kills 99.9% of bacteria if you wash your hands for at least 30 seconds. Part of the issue with triclosan is that people don't wash their hands long enough, so the more resistant bacteria persist and reproduce. Also, the scrubbing is to make sure that all the oils on their hand are washed away to avoid bacteria avoiding the antibacterial agent by hiding within them.",
"There are approved surgical foams and gels that are alcohol-based which take the place of the First Scrub as an alternative to the 3-5 minute wash at the sink with medicated, antimicrobial soap. \n\nThe aim is to reduce the load of organisms on the skin and prevent regrowth during the surgical procedure. If hands are visibly soiled, of course it is recommended that the surgical team member wash the grime off first, preferably before entering the hospital.\n\nSterile gloves are not leak proof or puncture proof. They are known to fail during procedures and often leaks/punctures are undetected during cases, even with double gloving, they're not 100%. The more effective the antimicrobial activity of the pre-scrub, the better. Alcohol-based hand-rubs have many positive attributes and are readily found at the scrub sinks. \n\n[Bonus article on efficacy of both.](_URL_0_)",
"I couldn't see any comments about spores. Some nasty bugs produce spores that are immune to those antibacterial cleaners. They stay dried out like seeds until they're put somewhere they can grow, like a human body, where they'll germinate and infect.\n\nWashing your hands quite literally washes those things off.",
"At each facility I have worked, you do an initial first scrub which consists of water, nail cleaner, cleanser and scrub brush. You clean your nails, soap up your sponge and clean hands, fingers, nails and arms. I also do this coming back from lunch. Before every other surgery, we have alcohol based cleanser that we use on our hands, fingers, nails and arms. Basically there are only two times a day we use water unless we see blood or other bodily fluids on our hands/arms. Then we must wash. Any other time we use cleanser. This has changed since I became a surgical technician 26 years ago. We used to have to scrub before each case. When you are doing 30 cataracts a day it can really abuse your skin when you have to use water and soap. Thank goodness for alcohol based cleanser."
]
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y4ln0 | why you only get caught for illegally downloading some things, but not others? | I've downloaded some things in the past (Community, HIMYM, etc.) and I've never been tracked or anything. But a few months ago I was downloading a file that turned out to be Iron Man 2 (I really didn't know it was that). My internet provider sent me an email warning me of the download, but why did they not mention the other things? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/y4ln0/eli5_why_you_only_get_caught_for_illegally/ | {
"a_id": [
"c5sa2mo"
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"score": [
2
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"text": [
"Pure luck. You just happened to be downloading the file at a time when the copyright police (basically a bunch of people at the big media companies) were tracking you."
]
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[]
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|
8t883y | Why didn't the turkish people attempt to reclaim any lost territory from the first world war? | From what I can tell Mustafa Ataturk was mainly concerned about social reform and building a modern turkey. Why did these moderate political views thrive in turkey during a time when facist and communist ideas where thriving all over the world? Where their any notable right wing fringe movements in turkey that wanted to restore the ottoman empire at its place of being the world power in the middle east? And if so, did they have any realistic chance of coming to power? | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/8t883y/why_didnt_the_turkish_people_attempt_to_reclaim/ | {
"a_id": [
"e164vvk"
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"score": [
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"text": [
"It's important to note that, at this time, the lands they lost with the exception of Saudi Arabia were all British and French colonies who were at the height of their power. Taking back Iraq or Syria or Palestine didn't mean going to war with some two-bit monarch or collapsing empire, it meant taking them from some of the strongest militaries in the world. Additionally, the ideals of the Arab Revolt were probably still very strong in many of these territories, and the Turks would have likely faced an unending insurgency if they tried to retake any of the old Ottoman territories."
]
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[]
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1nrq1n | what makes computer hacking difficult, and not something a computer itself does? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1nrq1n/eli5_what_makes_computer_hacking_difficult_and/ | {
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"Well in some cases, it does. But that's another story.\n\nConsider what computers do: very simple tasks, *very* fast. They don't (usually) screw up.\n\nNow hacking consists, fundamentally, of finding cases where people told the computer to do the wrong thing. At a very basic level, this is a deviation from expected behavior, which makes it...unpredictable. Computers suck at it because it's a *difficult* problem that can't easily be broken down into simple problems. \nOr in a nutshell, it is very hard to predict the unpredictable.",
"It's difficult for a few reasons:\n\nIn the past 20 years since computing got big, an entire *career field* has been created against hacking (computer and internet security).\n\nSince computing has gotten so much more powerful, it's difficult to overload security software which causes it to crash, leaving systems vulnerable.\n\nComputer manufacturers have had a lot of time to build systems within their operating system to overcome hacking attempts, and have a lot of people on staff working to make their systems unbreakable.\n\nAny software programmer hired to write high-level software has at least a basic knowledge of security, most probably try to hack their own software.\n\nCompanies pay big money to groups/individuals who find security holes in their software and then fix it. (But not before letting the government use them for a few months, amirite?)\n\nThere's more but I want to play GTA5 now.\n",
"Computer hacking, as the word was first used, is best described as clever, unexpected use of the technology. All it requires is intelligence and creativity.\n\nComputer cracking, the bypassing of restrictions placed there by the programmers of a system, should be impossible. But errors made by programmers leave corner cases where the system does not work as it should, allowing a user do do something the programmer did not permit. This is a battle of intellect between the programmer and the cracker, where all the cards should be in the hand of the programmer. Because of this, it should be difficult!\n\n(The difference between hacking and cracking is basically whether the original programmer would have allowed it if they knew! A good hack is applauded by the program's creator (I didn't know it could do that - Neat!), whereas an instance of a crack is reported to the authorities.)",
"First lets talk about why computer systems are hackable to begin with. Computers simply execute operations on a basic arithmetic/logical level. All of the complexity of programs, operating systems, graphical user interfaces, etc. boils down to these basic operations. They're just stacked on top of each other MANY times over by programmers to perform the more complex tasks that suit their needs/goals. The flaws in any given system, therefore, are not with the basic operation of the computer but with the greater overall logic or execution of the *person* chaining together these operations at a much higher level. There's a ton of room for error when you account for the sheer number of platforms and frameworks that are employed to accomplish varying tasks.\n\nA computer doesn't possess any sort of understanding of the purpose of the operations it is given, so it can't tell a programmer when they've made an exploitable mistake and it certainly couldn't repair itself. Without that level of self-awareness there's no way it could even begin to analyze the execution of OTHER systems all on its own. However, a computer *can* be programmed to check for certain flaws in a system and potentially exploit them if it is told explicitly what to do. Automating the process doesn't make a computer intelligent, though, and it still lacks the capacity to improvise and discover new flaws in the way a clever human might.\n\nI think a lot of people give too much credit to computers. They are fantastic pieces of equipment that enable us to do many, many things but at the end of the day they're not truly smart or magical. A computer is simply a tool."
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6dsk72 | why do some gifs load fine on the reddit app but others won't? | I've noticed it when swiping through pages, gifs will load fine, then one won't, then the next few will and one won't again, so I'm pretty sure it's not my internet connection. And it doesn't matter if I click into it or refresh the page. Am I missing something? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/6dsk72/eli5_why_do_some_gifs_load_fine_on_the_reddit_app/ | {
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"text": [
"I don't know why either. Happens to maybe 20% of gifs. There is an easy fix though. If it doesn't load, click the word 'imgur' just above the post title. Works a treat.",
"Reddit sync is the best app i have on my phone, works so well i bought the ad free version. It is so smooth and one of the most detailed apps i ever used! Defo give it a try if your problemo persists :)"
]
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[],
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15oxrf | How come some farts blow over in seconds, whilst others hang in the air for ages? | askscience | http://www.reddit.com/r/askscience/comments/15oxrf/how_come_some_farts_blow_over_in_seconds_whilst/ | {
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"text": [
"Best fucking question ever asked \rI dunno :/"
]
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| []
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[]
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|
||
4nzy31 | What did the soldiers of the hundred years war eat as rations? | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/4nzy31/what_did_the_soldiers_of_the_hundred_years_war/ | {
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"text": [
"Soldiers in the Hundred Years War did not receive rations as such. Commanders were supposed to provide food for their men (whether by taking it with them or by foraging/pillaging for it), but there was no system comparable to the Royal Navy's daily allotments of particular foods. Food might be provided by royal purveyance (where food was gathered by order of the king), but this proved to be politically unpopular and was largely replaced by contracted merchants providing supplies to military forces and garrisons like at Calais. What form did these supplies take? Primarily, various forms of grains: wheat, oat, barley, and malt are mentioned frequently. Beans and peas were also common for English military rations, though not to the same extent as the grains. For meat, pork and beef (presumably salted) were the usual military supplies. When soldiers were in the field, they would also forage for whatever they could find in the area. If they camped near a lake, they might fish. If they came upon a village, they would take bread. If they were passing by vineyards, the soldiers would drink as much as they could get their hands on, much to the irritation of their commanders. Although sometimes commanders attempted to limit the violence and destruction caused by their soldiers for political reasons, they had a limited ability to actually enforce discipline. Civilians caught in the path of medieval armies had very few options for protecting themselves or their livelihoods. "
]
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||
ckivjr | baby boomers are adamant that they had it far worse than proceeding generations, how is the opposite actually true? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/ckivjr/eli5_baby_boomers_are_adamant_that_they_had_it/ | {
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"text": [
"Let's imagine this. You're a new generation of cavemen and you have the ability to use wheeled carts to carry items. The generation before you complains on how the new generation has it \"easy\" compared to them where they had to carry every item. Although yes, the technological advancements weren't there, a new set of issues arrive for the newer generation too. What if the wheels break down? Larger advancements demands larger supplements. Can you really move at the same pace in carrying items as if you had no wheels? Regardless if you're skilled at carrying items beforehand? \n\nSame happens for the new generation. Each technological advancement brings a new set of complications for that specific grouping. Just because lets say, Africa doesn't have a large amount of people using smartphones doesn't mean that we can't complain about issues in our first world state. Someone had a leak in their home and wants to fix it, but then a homeless guy comes and says that they have it far worse in that they don't have a home at all. \n\nWith these examples, it comes more easy to understand the different perspectives that take place when talking about this topic."
]
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||
7gedwm | why do some things only taste good after a few tries? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/7gedwm/eli5_why_do_some_things_only_taste_good_after_a/ | {
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"text": [
"Your body automatically rejects new bitter flavors, as many poisons are bitter. But once you have tasted them several times and suffered zero ill effects, your nervous system (basically your brain) starts to adjust."
]
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| [
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|
||
289kuv | why do people remember car accidents or anything similar in slow motion? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/289kuv/eli5_why_do_people_remember_car_accidents_or/ | {
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"text": [
"The brain's perceptual ability can have a very wide or very narrow focus depending on the circumstances. Normally you are taking in sights, sounds, physical sensation, scents, etc, in a more or less balanced manner. At the first sight of danger, the brain can essentially turn off the perception of everything but the visual stimuli. \n\nWhat's happening is not really the perception of time being slowed, but an overwhelming level of visual detail being experienced all at once. Our memory perceives this as meaning the event must have lasted longer than it actually did.",
"Experts will say that people only recall time being slowed, because of the amount of visual detail recorded, but this is wrong. Events appearing slower is an actual experience.\n\nI was once in a stressful situation, but not life-threatening. There was nothing going on to distract me, and not a lot of detail to be recorded. Suddenly everything slowed down. I was aware it was happening at the time, and was trying to figure it out. I began walking, and was moving in slow motion. Others around me were walking in slow motion. After about four steps everything shifted back to normal. It shook me up, and I have never tried to replicate the event.\n\nWhenever I see a TV program showing a lion chasing a gazelle, and the tape has been put in slow motion, I wonder if that is what the gazelle is actually experiencing. There is probably a survival strategy that kicks in in certain stressful situations, such as a lion chasing you. It gives you \"more time\" to think of a way out"
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hznsb | Would a bottle of wine chill faster opened or unopened? | Assuming all other things being equal, would a bottle of wine chill faster with the cork still in (unopened) or popped (opened)? Or does it not make a difference either way? | askscience | http://www.reddit.com/r/askscience/comments/hznsb/would_a_bottle_of_wine_chill_faster_opened_or/ | {
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"text": [
"I don't think it'll make a significant difference either way. The neck is such a small surface area for heat to flow through. Circulating chilled water around the bottle is the way to do it quickly.",
"I'm curious why you think it might make a difference? What phenomena do you have in mind?",
"Protip: put some salt, wine bottle, and ice in a bucket. Fill the gaps with cold water. Swirl it a round a tad, and you'll have some cold wine asap. ",
"It should cool faster closed. There is a difference in heat capacity for systems at constant pressure or constant volume. If you are at constant pressure (open) you have the ability to do expansion (P*dV) work. At constant volume (closed), you can't do any work, so changes in energy (external temperature) all go into the internal energy (wine temperature).\n\nI think this effect will be incredibly minor for a bottle of wine because of the low surface area (this is purely a geometric concern) and probably small thermal expansion coefficient.\n\nEdit: Wikilink _URL_0_"
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131vgn | where republicans have gotten the idea that
obama is a "socialist", and why socialism is seen as
such a threat to republicans. | Edit: Is this *really* such a partisan question? Can we not objectively look at the definition of Socialism-An economy run by the government, to put it simply- and objectively look at the things Obama has done and make comparisons? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/131vgn/eli5_where_republicans_have_gotten_the_idea_that/ | {
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"The whole basis of the republican party is smaller government, socialism is more government, thus seen as a \"threat\" to republican ideals at the very core.",
"This is one of those questions that's hard to explain simply. There are a few different things affecting the answer.\n\nTo begin with, there are decades of negative propaganda in the US around the word \"socialism\". So, a lot of the people calling others socialists aren't actually referring to specific policies. They're just saying, \"He's a bad guy doing bad things!\" This is why you see things that don't make any sense like, \"Obama's a socialist fascist!\"\n\nOn top of that, there are very few (if any) countries in the world that are run purely according to the principles of a single political ideology. Everybody runs with a little bit of capitalism, a little bit of socialism, a little bit of democracy, a little bit of autocracy, et cetera. So, when someone says, \"That's socialism!\", , they probably actually mean, \"That would result in more government oversight than we have now.\" This is why they call Obamacare, or even clean water regulations socialist. \n\nThe strange part about this is that socialism does NOT necessarily mean \"an economy run by the government\". In fact, if you look at what Marx had to say about avoiding \"[alienating work](_URL_0_)\", it sounds almost anarchist. Many of the older socialist government-run economies liked to claim that they were just assisting the transition from capitalism to socialism, with it being understood that when the transition is complete, government could be radically scaled back. There was an assumption that focusing on profit above things like the good of mankind was a result of brainwashing, and once we overcame our brainwashing and saw how selfish we were being, we would all be smart enough to realize how foolish that was in the long term. \n\nIt turns out, however, that the desire to improve one's lot in life, even at your neighbor's expense, is a much more deep-seated desire than the original socialists expected. Capitalism said, \"Well, duh! Let's run with it. Every man for himself!\" Socialism said, \"If people aren't going to figure this out on their own, we need to put some smart people in charge to keep people's greed and selfishness in check.\" From that ideological difference, we come to the shorthand of \"Capitalists want less government and socialists want more.\"\n",
"Yes, it is a partisan question. Just look at the wording of it. If you were to leave out the whole \"Where Republicans have gotten the idea\" and \"such a threat\" parts, then you might have a question more people would be willing to look into answering. As it is, I'm not even going to bother talking to you about it."
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[],
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"https://en.wikipedia.org/wiki/Marx%27s_theory_of_alienation"
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3bctaz | why emergency vehicle (police/fire/ambulance) sirens sometimes sound like the driver is repeatedly pushing the siren button causing the pattern to constantly restart, rather than just keeping the siren on? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/3bctaz/eli5_why_emergency_vehicle_policefireambulance/ | {
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"Modern emergency vehicle sirens, typically made by federal or Whelen \n\nThe standard modes are usually \"wail\" and \"yelp\" which are the two typical police sirens. Then there is usually a button for an airhorn and a manual burst siren. \n\nThe manual burst siren is what they use to alert you to a traffic stop if you don't notice the flashing lights behind you. And airhorn is what they use to clear an intersection. \n\nThis is a good demo of the typical buttons in an emergency vehicle. _URL_0_\n\n\nFire trucks and old 50s era police cars often also have a secondary rotary siren, usually made by Whelen that sounds like this _URL_1_\n\nRotary sirens were also used in air-raid sirens. They have a motor that spins the a fan every few seconds, so the siren pulsates. \n\nSo I'm not sure which you're referring to. My gut tells me you're thinking of air-horns, or a cop who just likes playing with the buttons as they clear the intersection.",
"The changes in pattern and siren type are to keep those around the emergency vehicle alert. The human brain likes things in patterns so that you can concentrate on it less, and sirens, even when loud, will start to get faded out by your brain after a while. Think of it like music at a club, if it's the same repetitions over and over you start to notice it less and less. \n\nSo what they do is have the pitch and pattern change constantly to keep nearby drivers alert to the presence of the vehicle and ensure they will be ready to move out of the way if needed. Similar to how highways are always curved as to ensure drivers won't get drowsy or lose attention on a super straight road."
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"https://www.youtube.com/watch?v=uSVDiCkXmPk"
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3aotsd | why crt tv's have that line going through them when recorded by a camera | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/3aotsd/eli5_why_crt_tvs_have_that_line_going_through/ | {
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"Someone may want to confirm this, because it's just an educated guess, but I think the frame rate of the camera is such that it picks up the crt scanning lines in the way we see it..... similar to how a helicopter rotor may appear to spin slowly backwards.",
"CRTS work by an electron beam scanning down the screen line by line hitting phosphoros dots and lighting them up. It does this 50 times a second.\n\nAt the same time a camera is effectively doing the reverse, it is sampling it's light sensor line by line, 50 times a second. The problem is that the scan rates are rarely in sync, so the camera ends up catching the CRT halfway through it's scan.\n\nThere are special devices that are used by the television industry called genlocks which allow a camera and CRT tv to be synced so that the line does not appear"
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3p4133 | why can some animals go weeks without eating, but humans need food on a daily basis? | For instance snakes or big cats can eat an animal one day and not half to eat for the rest of the month | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/3p4133/eli5_why_can_some_animals_go_weeks_without_eating/ | {
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"Its just a habit. You as a human can probably go up to a month without eating, just burning your fat reserves. \n\nEdit: There are several reported cases of humans (pretty obese) to live from their fat alone for up to a year. ",
"Animals that don't eat as often tend to eat much more at each meal. For example, wolves eat only a couple of times a week, if that, but during each meal session they eat somewhere around 15% of their body weight in food. If humans ate like that, they would eat ~20-30 pounds of meat in a single meal.",
"Humans are perfectly capable to surviving while eating like predators (2-3 days worth of calories on some days, nothing on other days). It's just not comfortable and not ideal for long-term health. The idea that you'll get sick or go into \"starvation mode\" from not eating for a day is bullshit perpetrated by people who've never missed a meal in their life.\n\nSnakes are cold-blooded and therefore need very few calories to maintain their basic metabolic functions, as well as being ambush predators that use very little energy hunting.\n\nSome small invertebrates, like scorpions, have such efficient metabolisms and are so inactive that they can survive on one meal per month or less, because their body only uses the minimum required to keep their immune system and other vital functions going any time they're not actively hunting.",
"Humans do not need food on a daily basis, this eating daily thing is pretty new to our species. For the most part humans ate every other day. We are able to run for about 5 days straight only stopping to drink water while chasing our prey. Humans have the best endurance of any mammal. ",
"Humans don't actually need to eat all that often. One meal a day in terms of standard American size is enough for you to live. You might not like it since you haven't eaten that way before, but your body can. Multiple people have lived months before dying of starvation.\n\nAlso to clear up a misunderstanding you might have, other animals don't like to go weeks without eating. Most animals (humans too!) prefer to eat at least once a day. ",
"First of all your initial premise is wrong. Humans can go without food for a long time as well, but we cant go without water for long. ",
"We don't need food on a daily basis, it's simply what we prefer. If you have ever gone hungry you probably noticed that your hunger abated after a day or two. Human beings can go weeks without food provided you have the body fat for it but switching over from aerobic and carbohydrate based metabolism, to a more anaerobic and keytone based metabolism takes a few days. When you stop eating food your stomach and intestines have residual food left. This lasts a few hours. Then your liver has built up reserves of energy and this takes a day or two to become exhausted, at that point your body starts burning fat reserves but it's slow to switch to this. Your body breaks the fat and some muscle and organ protein down into ketone bodies which your body can use for energy. This is a slower process than the energy your liver can provide so you tend to be more lethargic and you don't get a burst of energy like you do after a trail mix bar but the energy that is there can last a long time as you burn fat. \n\nIf this goes on for a few weeks your body will start to cannibalize it's own organs and muscles in addition to the fat, if it goes on a very long time, several weeks for instance, this can weaken your heart and organs which will make you very weak and eventually lead to your death. \n\nYou can go weeks without food, it's not good for you but it wont' kill you. You can't go more than a few days without water before you start dying by comparison. \n\nCompared to animals there are a few big differences in our digestion and energy making organs. We have pretty tiny stomachs and ridiculously short digestive tracts compared to other animals. This comes from eating frequently, cooking our food which makes it easier to digest, and it's a good fit for our way of living. \n\nTake an animal like a lion for instance which can eat a much higher percentage of it's body weight in food compared to a human and it has a longer digestive tract to get every last bit of nutrients out of it that it can. Animal livers can also be much larger than human livers for body weight which allows them to store quick energy for longer periods without food. Our liver is very specialized though and it can do things that animal livers can't. For instance we can eat lots of caffeine and chocolate, which are poisonous to many animals and insects but our livers are able to break down and metabolise them quickly enough that it doesn't hurt us and we may even find them delicious. This is why dogs can't eat chocolate for instance, the something something thylobromide can't be metabolised fast enough and it can reach toxic levels where as our liver breaks it down very quickly. \n\nOn the other hand a dog liver can hold a lot of energy. So animals can eat more at once and go longer between meals. This is a good thing because when you hunt, you put yourself at risk of becoming hurt or killed, especially when hunting things that are bigger than you. The less often you need to do it, the less risk you take. Better to take down 1 bison a week and eat it all at once, than to kill one every day and just eat a little. \n\nThen you have cold blooded animals like reptiles which don't need to waste energy heating their bodies up so they can go very long periods of time without eating and without storing fat because their metabolic needs are far less than warm bodied animals. \n\nThen you have birds, which ironically are descended from reptiles yet their metabolism is a polar opposite, they must eat constantly because their bodies need large amounts of energy. Humming birds are at the extreme end and they burn so much energy flying they can't go very long at all without eating. I once saved a hummingbird that knocked itself out on my window. It was VERY weak when it regained consciousness, I could hold it in my hand and it just sat there staring at me and being very lethargic. Over a few hours I fed it soda pop by holding my finger over a straw and putting the end over it's beak and letting it get the HFCS energy. It became more active after doing this and I was able to release it and it flew away. ",
"What makes you think humans need food daily? "
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19436c | which medieval combat weapon was the most exclusive to use? | which weapons would've costed the most to own or needed the highest rank to use?
anything in your area of expertise dating before gunpowder really started to be used, to claify dates more precisely | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/19436c/which_medieval_combat_weapon_was_the_most/ | {
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"You needed a strong, fast warhorse to use a lance. So that was a prestigious weapon of the nobility. Long swords used a lot of metal and would have been expensive. Spears and clubs were the most simple weapons to construct and would have been available to the common foot soldier. The clergy (yeah, they fought in those days) frequently used maces because of a religious stigma against killing with a sword. I guess it was OK to bludgeon someone to death.",
"That's an interesting question, it's also a difficult question to answer. \n\nThe middle ages is basically 1,000 years long and is a massive geographical location with a lot of different cultures. As you head towards the end of the medieval period, who could run around with weapons became more restricted - but even then it is largely local customs. Do you have a more specific question? \n\nHowever, there are bits of awesomeness floating around: \n\n > Writ of King Edward I. to the Mayor and Sheriffs of London enjoining them to punish all bakers, brewers, and other misdoers walking the City by night with swords and bucklers and assaulting those they met; and further commanding that all corn sent to mills to be ground within the City should be delivered by weight to the miller, who was to return the same weight in flour. Dated Westminster, 28 Nov., 10 Edward I. [A.D. 1281].\n\nNote: Corn in medieval Europe often means \"The predominant crop of a region\". \n\nEDIT: Broadly speaking, weapons and armour were defined by your ability to afford them. If you could afford to armed and armoured as a knight, you'd be obliged to be able to fight amongst them (not be one). That being said, affording the arms, armour, and training of a knight is fantastically expensive - more the vast majority of people in the majority of the medieval period could realistically afford. \n\nEDIT2: Also, just because you have a weapon doesn't mean that you can fight with it. Fighting with (say) a Longsword on a battlefield without heavy armour is a death sentence. If you didn't own armour, you'd want to be a spearman or an archer. "
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152s01 | If most romantic languages descend from Latin, what are the roots of Latin? | I was looking up the roots of the word honor for an essay, and I found honos, then I wanted to know the roots of honos, and so it goes. | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/152s01/if_most_romantic_languages_descend_from_latin/ | {
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"I think you'll get a better answer from /r/linguistics, frankly, but the short answer is that it comes from the Italic branch of a (reconstructed) language called Proto-Indo-European. There's a \"family tree\" [here](_URL_0_).",
"There's a fascinating podcast called \"History of English\" that goes into this in detail. The first episode is an overview of English from ancient times till now, the next several go over the Indo-European language (the root of both English and Latin, as well as many other languages), including explanations of how linguists have learned about that language.",
"First of all, the Romance languages are descended from Vulgar Latin, a sort of Latin with a slightly different vocabulary and different grammar used in common speech.\n\nAnyway, as others said it's from the Italic branch of the larger Indo-European language family. [Here's a family tree](_URL_1_). Using linguistic tools and some guesswork linguists can reconstruct a hypothetical proto-Italic language, which would've split into the Italic languages and would've emerged from part of the also reconstructed proto-Indo-European language. But not much is known with certainty in this area. Latin also gets quite a bit of vocabulary from Greek, but it isn't descended from it, though it is related.\n\nIn terms of the word \"honor\", not every root can be traced reliably to proto-Indo-European stems, though many can. [This](_URL_0_) says that beyond Latin, the ultimate origin of \"honor\" is unknown.",
"I too find this subject very interesting. There is a theory that the Italic and Celtic languages share a common root language (besides proto-Indo-European, of course) _URL_0_\n\nI also recommend The Horse, the Wheel, and Language for a discussion of the common roots of all Indo-European languages. \n\n_URL_1_",
"You need to read the introduction (pp. 1-16) to Fortson's [*Indo-European Language and Culture: An Introduction*](_URL_0_). Do it. Do it now!\n\nIt's the nicest explanation of how Indo-European linguistics works I've ever seen. Amazing scholarly writing, if I may say so.\n\n(edit to change the link to go directly to the intro)",
"Italic languages, which used to be a relatively closely related branch of languages inhabiting the Italian peninsula contemporaneously with the Etruscan languages (a non-Indo-European language). These were consumed by Latin when the Romans conquered the peninsula _URL_1_ \n\n_URL_2_\n\n_URL_0_\n\nThat map doesn't necessarily cover what is and isn't Indo-European, but Etruscan and Raetic are thought to have been language isolates and not related to IE. And as a note, Greek is obviously not Italic. The Greeks were a seafaring people for a lengthy period of time, colonizing everywhere from the North of Africa, Eastern Spain, Sicily and southern Italy all the way north to the northern coasts of the Black Sea.\n\nIf you wish to go further back you verge on the theoretical. It's believed that the Italic languages made their incursion into central and southern Europe with the Celtic languages as one common language or closely related group of dialects, Italo-Celtic. \n\n_URL_3_\n\nI'd come to this as a caveat, though, as this is not an all accepted model for the languages before Italic. It's certainly plausible though. "
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"http://en.wikipedia.org/wiki/Italo-Celtic"
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hxqad | How territorial are pets about their food? | I have two cats to feed in two separate bowls, wondering what will happen if I only put food in one bowl. Is there any chance the unfed cat will starve, or will they share? | askscience | http://www.reddit.com/r/askscience/comments/hxqad/how_territorial_are_pets_about_their_food/ | {
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"You must perform this experiment, for science! It's by far the easiest way to find out for your particular cats.\n\nAnecdotal evidence time: In my experience, I have found that the answer varies wildly depending on the pet. Some don't mind sharing at all, others mind a great deal. My dog isn't aggressive enough to make sure that other dogs stay out of his bowl, so when friends bring over their dogs we have to move his food bowl. \n\nI don't know how your two cats would act if forced to share - there are too many variables.",
"There's absolutely no way to say without trying it, because it varies from pet to pet. Some won't mind at all, and others, even if they're big softies away from the food dish, will try to kill like the damned. If you want to find out, try it when they're both in chill moods and in a place that is equally theirs.",
"This isn't really the best question for /r/AskScience. Your answer is too dependent upon the personalities of your cats and their relationship with one another."
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3masti | how is it that vets can treat multiple types of animals with similar training as doctors who only have humans to deal with? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/3masti/eli5how_is_it_that_vets_can_treat_multiple_types/ | {
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"There are some veterinarians who do specialize. They specialize both when it comes to what sort of animals they treat and what sort of problems they treat. There are horse-doctors and Animal dentists for example.\n\nMost of them however are more general practitioners.\n\nThis is possible because the difference between a cat and a dog is not really all that big for example and a lot of general medical knowledge can easily be applied to lots of different animals. Being able to care for two different species does not take twice the general medical knowledge as being able to care for a single one.\n\nThe other factor is that we allow for a much greater room for error when it comes to animal care. If a pet could not be saved because a veterinarian did not know about some extremely obscure bit of knowledge about some rare animal malady that is considered slightly more acceptable than when it would happen to a human patient.",
"It may be due to the amount of ailments and issues that cats/dogs come up with comparatively to humans. As /u/Loki-L said, there is greater room for error when it comes to animals. Doctors for ailments regarding humans must know a wide range of maladies that affect us from the flu, to infections and wounds. For the most part, animals only have to deal with a smaller number of things before it becomes more specialized."
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