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{ "a_id": [ "chusi6h", "chw07e2" ], "score": [ 20, 2 ], "text": [ "To build a bit on /u/Sherbert42's answer: teleology (in a historiographical sense) is a form of historical enquiry which attempts to construct a narrative view of history as a progressive march in one direction; towards an inevitable end point. \n\nTo give one particularly notable and illustrative example of teleological thinking: look at 'Whig history', a school of thought [described by Herbert Butterfield](_URL_0_) which argued that all history can be considered as an inexorable march towards enlightenment/liberalism.\n\nThe problem with the teleological approach is that it tends towards sophistry: to use the Whig history example again, the idea that British-style liberal enlightenment is the apex of human progress, and that the eventual convergence of all history on that point is an inevitability, is deeply problematic. \n\nThe idea that you can divine a perfect (or in any way satisfactory) linear narrative in history become ludicrous almost as soon as you start to interrogate it to any depth. The construction of these teleological narratives generally involves highly selective use of evidence, straw men and the complete dismissal of countervailing viewpoints or interpretations.\n\nWhat always surprises me is that this prism for understanding history hasn't entirely gone out of fashion. Butterfield wrote *The Whig Interpretation of History* in 1931, about historians mostly of the 19th century, but Francis Fukuyama's 'End of History' theory in the 1990s owes a lot to these ideas: the idea that the fall of the Soviet Union represents the ultimate triumph of liberal democracy as \"the final form of human government\".\n\nEdit: as someone else pointed out in the comments, I mangled my understanding (misread old notes from uni and clearly wasn't paying enough attention) of Butterfield's place in the Whig canon — as a critic and taxonomist, not a part of the canon. Duly corrected/now going to go hang my head in shame.", "OP here, Thank you all of you for such thorough and thought provoking replies and comments. " ] }

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[ [ "http://cdn.preterhuman.net/texts/literature/general/Butterfield%20\\(Herbert\\)%20The%20Whig%20Interpretation%20of%20History.pdf" ], [] ]

{ "a_id": [ "cpueb65", "cpuebre", "cpuefjo", "cpueg8z", "cpueh07", "cpuelrj", "cpuf10s", "cpuf22i", "cpuh9n6", "cpuhr1z", "cpukahq" ], "score": [ 2, 16, 5, 4, 4, 9, 3, 2, 3, 2, 3 ], "text": [ "Whichever is the correct one. There's no way of knowing which is the correct one, other than weighing yourself on another scale, perhaps at a doctor's office. If you think the differences are because of the crooked floor, try to find a place in your house where the floor isn't crooked. Maybe even take the scale someplace else and weigh yourself there.", "Find something in your house that you know weighs a certain amount for sure. E.g. a new bag of rice or potatoes or whatever. Weigh that in different areas of your house and see where you get the most accurate reading. Just use your scale in that spot.", "Trust the reading taken on a hard, level floor.", "This may be a dumb question, but just to make sure, are you re-weighing yourself immediately and getting different readings, or weighing yourself at different times throughout the day?", "Buy a leveler, for like a buck or two. The little tubes with liquid in them... They show you where the floor is level.", "Trust the one that makes you happier. Odds are the difference isn't great enough to matter.", "Just keep in the same spot all the time and use that measurement. Does it matter if it displays one or two kg more/less? If so, you should get a proper calibrated scale but they are not cheap. If a kilogram or two doesn't matter just keep it in the same spot because then you will at least be able to track weight changes.\n\nAt the gym I go to there is a scale called VB2-200 which is a calibrated scale. It costs around 5000SEK though (580USD) but it is damn accurate and we use to weigh plates as well.", "Weigh yourself somewhere else.\n\nWhere I live pharmacies have very accurate scales that they let you use.\n\nSimply use one like that and then go home without eating, or shitting, or taking of your clothes or wanting too long to find out in which place your scale is the most accurate.\n\nI assume you don't do anything like weightlifting or else you probably wouldn't have asked, but if you have a friend who owns weights you might simply borrow them and test things out with that.\n\nIf you don't have any weights you can borrow use something else with a known weight. Most groceries are sold with resonable accurate weights printed on them but usually they are sold in small portions. Buy something that is heavy and usefull in large portions.\n\nAs somebody has already suggested water is pretty good. Water has a density of 1 kg/l under normal conditions so you can buy a case of 12 1l bottles and take them with you on the scale. The bottles should be made out of plastic so that their weight is negligible. Just check in which location the difference of you with a know weight in water and without matches best to the difference the scale shows. (if you want to be real accurate you can buy more bottles and drink half of them) weighing yourself with a case full of empty bottles and a case full of full bottles in turn so the only real difference will be the weight of the water.\n\n", "Put a coin on the hard floors. If it rolls, it's slanted.", "Don't worry about it, its prob. not that correct anyway. \nJust always weight you self in the same spot that gives you repeated readings that are the same. \n\ni.e. test the scales in one spot 3 times, getting of and on completely each time. the spot that gives you the same results is the winner.\n\nIf you are trying to lose/gain weight, watch the change not the amount.", "Bathroom scales should not be used to find out how much you weigh, they should be used to monitor changes in your weight. Expensive ones may be calibrated before leaving the factory but then they are never again calibrated.\n\nThe best practice for them is to leave it in one location and try to weigh yourself at the same time of day each time.\n\nIf you want to find out your true weight I recommend finding out next time you are at the doctors office." ] }

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{ "a_id": [ "cquornj", "cquouvk" ], "score": [ 25, 6 ], "text": [ "Any TV show can mention brand names.\n\nThey usually don't, because:\n\n* it makes sit harder to place ads for that product and its competitors\n* it can date the show and make it less desirable in syndication\n* viewers often have strong brand affinities, and might not relate to characters who use brands they do not like\n\n*Family Guy* is basically making fun of this adversion.", "They can, they just choose not to. The reason isn't related to lawsuits, either -- there's just often a policy of not mentioning by name any companies or products who are not advertisers. If Homer Simpson is drinking Coke, and Pepsi advertises on Fox, they'll object (this actually did happen for The Simpsons when mentioning Hewlett Packard). And in the reverse, if they mock or insult a real product, the producer of that product will object when they want to advertise -- notoriously, a producer of gas ovens threatened to pull their ads from CBS if Rod Serling, creator of *The Twilight Zone*, did an episode about the Holocaust, because gas chambers depicted *gas* in a bad light.\n\nSo there's no reason why shows *can't* mention real-world products, it's just usually avoided by network executives. Family Guy is evidently an exception. Perhaps the Family Guy producers persuaded the network that their jokes wouldn't work with knockoff brands the way The Simpsons' jokes would, or perhaps the executives at the time Family Guy was launched were less strict about the policy." ] }

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{ "a_id": [ "d1c8n1r", "d1c9w0h" ], "score": [ 3, 2 ], "text": [ "They don't know the password, but they do know when you have set it. You tell them the password when you set it, but they don't remember the password, only its \"checksum\", or \"salted hash\", and forget the original password. which can be calculated from the original password and data that don't change during the lifetime of the account. \n\nThey don't have to know your password to check against it - they can just compute the checksum. They don't have to know the password to tell you when you have set it - they only need the timestamp for that.\n\nThis is just an ELI5 explanation, as crypto is extremely complex, counterintuitive and hard to understand.", "Passwords are not encrypted, they are hashed. Theoretically : encryption is a two way street, you can go from plaintext to encrypted and encrypted to plaintext. Hashing is a one way street, you can only go from plaintext to hash, NOT hash to plaintext.\n\nSince passwords are stored using that one way function, some enterprises feel that keeping them is not a security threat." ] }

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{ "a_id": [ "cdehdi4" ], "score": [ 8 ], "text": [ "Your brain cells will eventually age and die. If you replace those you can technically live forever, but will you still really be yourself?\n\nThis concept has been debated since the Ancient Greeks _URL_0_" ] }

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[ [ "http://en.wikipedia.org/wiki/Ship_of_Theseus" ] ]

{ "a_id": [ "c83s712" ], "score": [ 11 ], "text": [ "The \"observer effect\" and \"measurement\" problems are commonly misrepresented on the internet by people who are obsessed with new-age pseudoscience. It has nothing to do with conciousness or anything magical. To put it in ELI5 terms:\n\nImagine that we you are blindfolded and sitting in a chair. I have set up a machine that can always shoot an apple across the room and have it whiz by right in front of your face. You, being blindfolded, have to \"detect\" when the apple has passes by you by listening to a hair dryer that I have taped to your head. When the apple passes in front of the hair dryer, it changes the sound of the air being blown. The hairdryer will not change the flight of the apple in any way significant to our observations. To detect the apple, you have interacted with it, but not changed it. This is an observation made at our regular, real world scale.\n\nNow imagine we repeat the experiment with a paper ball instead of an apple. In this case, we'll still have to interact with the paper ball to detect it, but since the paper ball is so light, it's *going* to affect the paper ball's trajectory. This is an observation made at a quantum scale scale.\n\nOn a quantum scale, you can't \"see\" an electron or any other quantum particle. You have to interact with them to detect them, and interacting with them changes them. that's the problem." ] }

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{ "a_id": [ "csgp0pt", "csgqppj", "csgqz9r", "csgr3ar" ], "score": [ 13, 2, 3, 18 ], "text": [ "Their art isn't in the music itself, but in the selection, order, and pacing of the music. They have to pick the right songs to fit the mood, then put them in the right order, at the right pace, to get the feeling that they're looking for. DJs are essentially the audio version of collage artists. Anyone can be a DJ, just like anyone make a collage, but there's a massive variation in quality between some kid that does it once or twice, and someone that's spent years treating it as a skill and has developed an artist's eye for it. ", "The DJs you're probably referring to are the big ones at EDC, Ultra, etc. Those guys produce a lot of the music they play or they remix those sings. They do play other peoples music as well, but they are also putting their own spin on it.", "What Pesto says is right, but there's also a lot more to any DJ worth their salt. Any numbnut with a preamp soundboard and some speakers can cue up a playlist and press spacebar. Any Joe with DJware or a multichannel board can crossfade to a new track as a previous one ends.\n\nTruly DJing a live set well, like the pros do, involves not only knowing every single facet of every song on your computer backwards and forwards but also involves being able to assign elements of those songs to effects controllers and changing and intermixing those songs on the fly to make whole new songs. Youtube mashups and you'll begin to see some of what's possible: _URL_0_ Most effects are assigned to buttons (which then have to be accurately memorized so as to be used properly during a show), but most pro DJ tools also allow effects buttons to be assigned on the fly, so there's a LOT of room for customization.\n\nAre there DJs who press play, and then sit back and piddle on Facebook? Yes, and they serve a purpose. There's a niche for everything. Many people know the original (vocal) mix of a given popular song. Musically literate fans of DJs and their associated music also know fifteen other (re)mixes, both official and non, and can differentiate between most of those and what constitutes something created uniquely on the fly. There's a very real skill involved. Youtube mashups. I think you'll find some truly eye-/mind-opening things DJs can do.", "\"Art\" is a form of expression.\n\nImagine that 100 people are going to be showing up to your house in an hour. How will you entertain them? Playing music is a good option. Do you have the right music to play? Would you just turn on the radio? Go to Pandora? \n\nRadios have commercials. Songs don't always compliment one another. \n\nBut let's say you don't want to risk having your party fail due to poor music selection... so you spend some time listening to songs, figuring out which ones compliment one another, which flow together, which ones get the crowd pumped and excited, and which ones give them a short breather so they can get ready for the next song.\n\nBut crap... that takes a lot of effort. Sure, pressing \"play\" on a machine may end up with a similar result... but you don't want to use a machine for this. You want to learn the fine-motor skills and muscle memory required to fluidly operate your music gear covered in buttons and switches. Like an audible chef, you craft a meal of sounds and rhythms for the crowds' ears... you manage to completely hide and obscure the pattern of song selection from the crowd to the point that the entire experience feels like one long ride of enjoyment. All those songs made by all those other artists might as well be different brands of paint being combined onto the DJ's percussive canvas.\n\nSo, to answer your question, the reason that people pay to see these shows is because these DJs provide a service that **not everyone** can do. And, sure, while the entry barriers to becoming a \"Dj\" are not very high, some Djs are simply better than others and can provide better experiences than their competitors.... so much so that fan bases develop and seek out opportunities to exchange their money (which plays no music) for temporary exposure to auditory stimuli that is otherwise unavailable.\n\nAt the end of the day, an experienced, talented DJ (just like any musician) can combine layers of sound in a way that taps them directly into the minds of their audience. That's pretty neat.\n\nImagine yourself on stage with some tables, wires, and buttons. Before you is a crowd of thousands. They are there because you have created something that meant something to them. You are there because you are an artist." ] }

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[ [], [], [ "https://www.youtube.com/watch?v=lTx3G6h2xyA" ], [] ]

{ "a_id": [ "dewvl90" ], "score": [ 4 ], "text": [ "The computer sent data through the phone line. Since the phone line transmits sound data - the computer was literally generating sounds that could be interpreted as data - high and low pitched squeals that represent the data you are sending or receiving. It was like a very rapid morse code.\n\nIf you picked up the phone, you would be adding your own sounds on top of the computer's sounds. The computer at the other end wouldn't know that you picked up the phone, it would just assume that you're sending data to, and this would screw up all of the data that gets sent." ] }

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{ "a_id": [ "dpb4wn9", "dpbkqcq" ], "score": [ 192, 4 ], "text": [ "So, for our friends that don't know, the buzzing is a signal in the AM range.\n\nThe effect is well known since the rollout of GSM in Europe begun (see Stephen Temple's _\"Inside the Mobile Revolution_\", Ch. 22). What's happening is that in TDMA, each transmitter gets a time slot in which to transmit, and then remains silent until the next slot. This pattern (transmit-silence-transmit) leads to the power amp delivering large amounts of energy within either the 850/950 or 1800/1900 MHz GSM bands, and in these bands it results at a ~217 Hz-modulated intervals IIRC. The signal is detected on any transistors or diode structures in chips, on multiple points of an amplifier simultaneously, including power regulator chips, batteries, and so on. It can occur even inside the handset itself. In GSM's 800-900 MHz range, any 80mm-long copper trace works like a quarter wave antenna, or stripline resonator.\n\nYou can see the spectrum of the burst [here](_URL_0_). The transmission power is near 2 Watts (yeah, GSM is power hungry). The resulting detection at an audio chip results in a voltage transient that looks like [this](_URL_2_); note the shift in both the supply and the ground. The output of the amplifier will eventually be clipped and filtered down to the audible range, but distortion can produce frequency components at any sum/difference of multiples of the original frequencies.\n\nThe reasons subsequent RANs (UTRAN, GERAN, E-UTRAN) don't present this problem are:\n\n* First and foremost, awareness of the problem. For example, back in 1990, when GSM was being rolled out across EU, this interference even affected devices like hearing aids, and there was major cause for concern, which translated in safety requirements for the development of subsequent standards\n* TDMA was abandoned. Instead, CDMA was adopted, where each channel uses the entire spectrum all the time, and multiplexing is achieved with frequency convolution with a signal that is orthogonal between every pair of transmitters; read more [here](_URL_1_)\n* Power requirements for user equipment became more stringent. For example, one of the first prototype chips for E-UTRAN claimed power consumption below 100 mW during the demo; see [here](_URL_3_). _Don't take that at face value, the demo was a tranmission of a few seconds. Still a remarkable difference w/ GSM_.\n\nI'm not aware if audio components changed their design to avoid problems like this.", "My iPhone 6 makes my guitar amp buzz. Any elaboration on that? " ] }

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[ [ "https://m.eet.com/media/1072712/C0433-Figure1.gif", "https://en.wikipedia.org/wiki/Code-division_multiple_access#Code-division_multiplexing_.28synchronous_CDMA.29", "https://m.eet.com/media/1072713/C0433-Figure2.gif", "https://web.archive.org/web/20110927212306/http://www.electronicsweekly.com/Articles/2007/09/14/42179/ntt-docomo-develops-low-power-chip-for-3g-lte-handsets.htm" ], [] ]

{ "a_id": [ "cnhz64x" ], "score": [ 2 ], "text": [ "There was a non-binding referendum is 2012, but most people see it for the sham it was.\n\nThe pro-statehood ruling party rigged it so they first asked if they people preferred the status quo, then asked the remaining people if the wanted statehood. If they asked the questions in the other order, they would have gotten a different answer." ] }

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{ "a_id": [ "cnkblcg" ], "score": [ 3 ], "text": [ "I'll take a shot at this. I think many people will agree they can \"feel\" low-frequency (bass) sounds in their chest when loud enough. We can perceive this vibration in our bodies with other senses, probably [somatosensation](_URL_3_) (i.e. touch), perhaps with [proprioception](_URL_0_). I found [this paper](_URL_1_), which measured chest vibration due to jet engine sounds and found a resonance at 63-100 Hz, indicating sounds in this frequency range might possibly be felt in the chest. [This paper](_URL_2_) basically confirmed that by reporting that the perceptual rating of vibration in response to low frequency sound was better correlated with accelerometer measurements on the chest/abdomen compared to the head. This supports the \"chest-thumping\" idea of bass sounds.\n\nAs far as actual studies with deaf individuals, I could only find a paper briefly discussed in [this review](_URL_4_) but couldn't find a copy of the actual paper (Yamada et al., Jnl Low Freq Noise Vibn 2, 32). Anyway, supposedly the deaf subjects could perceive low-frequency sounds at levels only 40-50 dB above normal hearing subjects. For reference, we usually consider a deficit of > 90 dB to be \"profound hearing loss\". This indicates the deaf subjects were probably using another cue (e.g. vibratory) to perceive the sound. \n\nIt should be noted that deaf individuals can have some residual hearing that allows them to perceive very intense sounds. I have a friend with thresholds at something like 105 dB SPL, so he can hear something like a loud power tool. Of course, for these sounds there's the vibration sense as well, so the perception sort-of merges together. There's also the sense of pain, which kicks in around 130-140 dB SPL (think standing next to a jet engine). \n\nedit: typos\n" ] }

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[ [ "http://en.wikipedia.org/wiki/Proprioception", "http://europepmc.org/abstract/med/11817618", "http://www.noiseandhealth.org/article.asp?issn=1463-1741;year=2011;volume=13;issue=50;spage=2;epage=8;aulast=Takahashi", "http://en.wikipedia.org/wiki/Somatosensory_system", "http://waubrafoundation.org.au/wp-content/uploads/2013/04/Leventhall-LFN-Whatweknow.pdf" ] ]

{ "a_id": [ "e74of12" ], "score": [ 5 ], "text": [ "They did...it's all over the sources...\n\nThe Parthians crossed the Euphrates only twice. In 51 Cicero feared a Parthian invasion into Cilicia, but it did not materialize, and the brief Parthian campaign following Crassus' defeat fizzled out quickly. Plutarch claims that Pompey reached out to the Parthians for asylum, but he ended up going to Egypt instead and the Parthians were not active on the Roman frontier for most of the 40s. A Parthian campaign in 41, led by the younger Labienus, was initially successful, but they were disastrously defeated by Ventidius Bassus, losing the crown prince Pacorus. The Caesarians' success at Philippi allowed Antony to launch a large expedition into Armenia, which was not particularly successful but was not followed by a Parthian counterattack. Though wars were occasionally fought in Armenia, and the Romans successfully invaded Parthia a few times (under Trajan and Septimius Severus, for example), the Parthians did not again cross the Euphrates. " ] }

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{ "a_id": [ "ej67a85" ], "score": [ 13 ], "text": [ "Not in any sense of the term that would make sense from a human perspective, for sure: by definition, single-celled organisms don't have nerve cells, and what we call \"pain\" is entirely a nervous-system response to various stimuli." ] }

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{ "a_id": [ "cn4n0bs" ], "score": [ 2 ], "text": [ "It is a response to the famous EPR (Einstein, Podolsky and Rosen) paper written in 1935 where they described a thought experiment leading to what we today know as quantum entanglement. Or to quote them: \"spooky action at a distance\". \n\nEntanglement can be briefly explained by two entangled electrons (A and B) being in the combined state where one has spin up and one has spin down (in some direction). We do not know which is which, but we do know that if electron A is measured to have spin up, electron B will for sure have spin down. An important thing to note here is that the outcome of the measurements is not physically decided (even in quantum mechanics), so the outcome is \"chosen\" the moment the first electron is measured. The second electron will immediately obtain the opposite spin value than the first one.\n\nIf the electrons are separated by a large distance (say 1 light year), it could be interpreted that some signal is sent faster than light, since the second electron will choose its state right after the first electron is measured. This is called non-locality.\n\nIn this paper and after, many argued that quantum mechanics was indeed an incomplete theory. Some people suggested that there must be some *hidden variable* (this could be a number, a set of variables, whatever), that will solve all of the problems with non-locality, and maybe even remove the probabilistic nature of quantum mechanics. Once these variables are known, these weird effects disappear. \n\nSo now to Bell's theorem. In 1964, Bell published a paper called *On the Einstein Podolsky Rosen paradox* where he showed that if we assume some hidden variable that takes away all the uncertainty in the experiment described in the EPR paper, there is a measurable physical quantity that should follow some inequality that is proven to be **false** both theoretically and experimentally.\nIn other words, any hidden variable as described above is inconsistent with the postulates of quantum mechanics. This is the consequence of Bell's theorem.\n\nSo was Einstein wrong? Well, modern formulations of locality (the speed of light being upper limit) usually state that no *information* travels faster than the speed of light. And as far as we know, quantum entanglement cannot be used to send information faster than light because we cannot control the outcome of the experiment (electron A gets spin up or down)." ] }

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{ "a_id": [ "c1kophu" ], "score": [ 3 ], "text": [ "Seems like a fairly in-depth article. Not sure why people would call it anti-science as such, everything I read was more or less what I have read elsewhere.\n\nWhat does worry me was the section about mobile generators being brought in to provide power for the cooling but the \"plug not fitting\". Now I'm no engineer, but surely with the level of expertise available onsite, would it not be possible to make it fit?? I.e. Rip out whatever terminals are there and connect it up somehow?\n\nAnyway all sounds fairly plausible and at least grounded in reality." ] }

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[ "http://web.mit.edu/oehmen/www/", "http://theenergycollective.com/barrybrook/53461/fukushima-nuclear-accident-simple-and-accurate-explanation" ]

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{ "a_id": [ "d0508w1", "d050fss", "d050gnq", "d050q5j" ], "score": [ 2, 50, 6, 2 ], "text": [ "I recently had to watch this video in my biology class and it explains how bacteria \"talk\" with each other and how we can use their \"language\" to enhance or inhibit their communication. _URL_0_", "[Here is an article you may want to read](_URL_0_) I'll post a little of the article so my comment doesn't get deleted. \nScientists have come across a potential game-changer in the fight against drug-resistant superbugs - a new class of antibiotic that is resistant to resistance. Not only does the new compound - which comes from soil bacteria - kill deadly superbugs like MRSA, but also - because of the way it destroys their cell wall - the pathogens will find it very difficult to mutate into resistant strains", "There are several different facets of research going on. They are really starting to scale up the antibiotic research, as well as alternate treatments for infections.\n\nOne of the alternate treatments that I am aware of is a PPMO, which stands for peptide-conjugated phosphorodiamidate morpholino oligomer. I'm not entirely sure how they effect bacteria, so this part may be inaccurate, but instead of killing the whole bacteria, it just annihilates the genes inside the bacteria. The PPMO is created for specific genes, so it won't start killing off all of our own genes. It's an interesting treatment that has gone through a little bit of animal testing with positive results, but it's a long way from being used in humans.\n\nThere is a similar concept being researched that uses viruses to kind of blow up bacteria cells. They latch on to the bacteria and overload the cell with their own DNA eventually causing the bacteria to burst open, which destroys it. This treatment is also intended to be used in very specific infections. As far as I remember, there haven't been animal trials, but this could also be wrong, I haven't checked in a while. The benefit of these antibiotics is that they can catered for specific infections, instead of killing all of the good bacteria in your body as well as the bad.\n\nThere was another actual antibiotic that I was told about that is called texobactin or something like that. I think they used it to treat lab mice that had MRSA. It was a big deal when it happened but I just don't remember it off the top of my head. It looked very promising but it was a few years away from clinical trials when I saw it. I'm sure they are further along in research now.\n\nResearchers are very aware that new treatments for infections are needed, and they are certainly working on the problem. More and more money is being granted to researchers about the potential of antibiotic resistant infections and treatments. This kind of research just takes a long time, because it has to be so thoroughly studied.\n\nI know there is a lot of scary stuff about antibiotic resistant infections, but there are a lot of people working on the problem. The antibiotic apocalypse could happen if nothing viable comes out of the research, but there are a lot of promising things being done currently, so I think it is unlikely. \n\nI am just a pharmacy tech, and I like talking to the pharmacists about new drugs. There is more than those three things being studied, but those were the promising ones that I remembered. Maybe someone else can chime in and mention others.\n\n\n", "There's a [full report](_URL_0_) on _URL_1_. I don't know where things are but the key recommendations are:\n\n(1) improving our surveillance of the rise of antibiotic‐resistant bacteria to enable effective response, stop outbreaks, and limit the spread of antibiotic‐resistant organisms, and acting on surveillance data to implement appropriate infection control;\n\n(2) increasing the longevity of current antibiotics, by improving the appropriate use of existing antibiotics, preventing the spread of antibiotic‐resistant bacteria and scaling up proven interventions to decrease the rate at which microbes develop resistance to current antibiotics;\n\n(3) increasing the rate at which new antibiotics, as well as other interventions, are discovered and developed." ] }

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[ [ "https://www.ted.com/talks/bonnie_bassler_on_how_bacteria_communicate?language=en" ], [ "http://www.medicalnewstoday.com/articles/287745.php" ], [], [ "https://www.whitehouse.gov/sites/default/files/microsites/ostp/PCAST/pcast_carb_report_sept2014.pdf", "whitehouse.gov" ] ]

{ "a_id": [ "c70rvek", "c70sy2p" ], "score": [ 3, 2 ], "text": [ "Manatees getting hit by propellors and bleeding out. Usually they get hit multiple time in their life, and are killed by particularly brutal hits.", "Elephants often lose their teeth at around 40-60 years of age and die of starvation." ] }

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{ "a_id": [ "cwtfbh8", "cwtff0x" ], "score": [ 2, 2 ], "text": [ "The medieval warm period was not as extreme, and came on much more gradually. The current one has been sudden and steady, and we have a clear cause for it: increased greenhouse gases in the atmosphere. We've increased the atmosphere's carbon dioxide content by 1/3, for example - that's a huge effect on a planetary scale. The rise almost exactly mirrors the growth of human industry, and even tapers off briefly at the collapse of the Soviet Union and its industrial capacity. \n\nWe have reliable climate records dating back tens of thousands of years from e.g. ice cores, and we are pretty sure this warming isn't like the others.", "1) Scale: It wasn't warming as much as we've already warmed the planet. \n2) Cause: Medieval peoples couldn't pump stuff into the atmosphere on anywhere near the scale we can. It was caused by things beyond their control. \nThis time around we are certain that we are the cause of the warming, that means we have to be the ones doing something about it." ] }

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{ "a_id": [ "dmyiqfm", "dmytgo3" ], "score": [ 3, 3 ], "text": [ "Type of radiation is determined by the material that emits it. Gamma radiation is electomagnetic radiation, like radio waves, microwave, x-rays, gamma rays... they are typically formed when a charge (electron) is accelerated or decelerated or moved in a circular path (which is an acceleration btw). It can also be formed when an electron jumps between shells in an atom (different energy states).\nAlpha radiation is essentially helium atom cores. They typically form as a result of a radioactive decay. Similar thing for beta except they are electrons.\n", "The type of radiation released depends on the particular isotope.\n\nAlpha radiation is helium atom nuclei (2 protons and 2 neutrons), which are ejected from a large atomic nucleus. In general, alpha radiation occurs in very large nuclei (things like uranium: 92 protons, 146 neutrons). Essentially, the nucleus is so big, that it can barely hold together against the repulsion between all the positively charged protons - so a cluster of protons gets ejected, taking some neutrons with it.\n\nBeta radiation tends to occur when the ratio of neutrons to protons in the nucleus is wrong. For light atoms, the optimal ratio is roughly 1:1, but as the nuclei get heavier, you need more neutrons (uranium is roughly 1 proton to 1.5 neutrons). \n\nIf a nucleus has too many neutrons, a neutron can transform into a proton and an electron. The electron can't stay in the nucleus, so gets kicked out as beta radiation. \n\nIf a nucleus has too many protons, a proton can transform into a neutron and a positron (a positively charged electron). The positron can't stay, so gets kicked out as (positively charged) beta radiation. \n\nGamma rays are just pure energy. They are released from a nucleus when it has too much energy - think of the protons and neutrons in the nucleus like dozens of those little magnets you can make scultpures from. Sometimes, the magnets can hold a position which isn't optimal, and then suddenly, they'll find a better position and bind tighter. When this happens in a nucleus, you get a gamma ray. \n\nGamma rays are released when alpha or beta radiation is produced. If you have a big nucleus, and an alpha breaks off, the nucleus is going to be a bit lopsided, so it will rearrange and form a more compact shape, releasing a gamma ray at the same time. \n\nA similar sort of thing happens with beta radiation - when a proton converts to a neutron, this can leave the nucleus a bit uneven. Sometimes, the energy is immediately released and it all goes into the beta radiation, but sometimes, some of the energy comes out separately as a gamma ray. " ] }

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{ "a_id": [ "c265wvw", "c266peu", "c266sg8", "c266wup", "c268p2m" ], "score": [ 10, 2, 2, 3, 2 ], "text": [ "People survive quite well on liquid diets for long periods of time. Google might turn up more information if you search for [tube feeding](_URL_0_). For people who can't tolerate solid food for any reason, a tube can be placed through the nose or through an incision into the stomach, and fluid given through that tube can meet all nutritional needs.\n\nThe lack of solid matter may cause loose stools and discomfort, but that can usually be dealt with by making sure the feeding solution contains enough fiber.", "I had to have my jaw wired shut. I would have rather had a broken leg, that's how uncomfortable it was, however I ate as good as I've ever eaten. \n\nOf course there were solids in what I drank, but it could be defined as an all liquid diet. ", "The intestines do not *need*, per se, to consume solid foods in order to function properly. All nutrients can easily be gotten through liquid forms, and then some. That being said, liquid diets tend to come out the ass a lot more messy. Dietary fiber does alleviate a lot of this, but it is not perfect.\n\nAlso, risk for [diverticulotis/diverticulitis](_URL_0_) do rise. Eating solid foods is like resistance training for the muscular intestinal wall, over time (not a few weeks, but a much longer time) the intestinal wall can become weaker if not adequately stressed and develop diverticulum.\n\nAlthough not optimal, you can live on a solid-free diet.", "Hate to answer a question with a question, but I heard somehwere that it was possible to survive on only coconut milk - apparently it has the perfect number of whatever it is we need.\n\ncan any one give further information? it's slightly related to original post", "I lived for many months on a liquid diet, when I had cancer and the radiation treatments damaged my mouth. Eventually, I couldn't even drink liquids anymore, so I had a catheter installed and started taking food through an IV.\n\nWhile I was on the liquid diet, my digestive system functioned normally, I had solid waste and all that. After I started taking food through the IV, my digestive system seemed to go dormant; when treatments ended and I started eating again I passed odorless \"baby stools\" for a while until my gut flora came back." ] }

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[ [ "http://en.wikipedia.org/wiki/Feeding_tube" ], [], [ "http://en.wikipedia.org/wiki/Diverticulitis" ], [], [] ]

{ "a_id": [ "dk2eqm7" ], "score": [ 6 ], "text": [ "All planets in the Solar System orbit in almost the same plane, and their axes of rotation are almost perpendicular to such plane. (Only exception is Uranus). So you can define East as the direction the planet is rotating, and North as 90° left of the East.\n\nWe also have reference frames and coordinate systems: cartesian or spherical, centered on the Sun or centered on a planet, inertial or rotating. See [this recent thread](_URL_0_).\n" ] }

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[ [ "https://www.reddit.com/r/askscience/comments/6itmue/in_earth_travel_we_use_north_south_east_and_west/" ] ]

{ "a_id": [ "c6x9xov", "c6xa8mk" ], "score": [ 3, 8 ], "text": [ "Where did you hear this if I may ask? ", "Well life expectancy is a very skewed statistic, because infant mortality deflates it substantially. The upper-classes could expect to live to the beginning of what we'd call \"old-age\" (about 60s, 70 and above was more of a gamble) if they weren't taken ill or killed in battle. It's possible- there would be plenty of old knights over the age of 50 to take part- but it seems unlikely. Maybe your source meant a third of knights in England were over 50 at the time of Agincourt?" ] }

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{ "a_id": [ "e9b2nh4", "e9b4u8w", "e9bckvn", "e9bclza" ], "score": [ 12, 2, 2, 2 ], "text": [ "Fireworks can look great on video if you have a good enough camera. Cheap cameras, like the ones in our phones, can't handle low light conditions very well and have a hard time focusing on the rapid flashes coming from a firework. The camera is constantly trying to auto focus but can't, resulting in a blurry image. ", "[Video compression work by detecting similarities from one frame to the next and encoding the difference between successive frames. This is usully done by cutting each frame into tiny blocks and then sending only the blocks that have changed. Some things like fireworks, snow or confetti will change most of the blocks in every frame, forcing the compression algorithm to lower quality significantly to keep up.](_URL_0_)", "Fireworks [can look amazing ](_URL_0_) on video. You just need the right equipment. ", "The other part of the problem is that fireworks are HUGE. You feel a certain way when you experience something much much larger than yourself. \n\nYour TV just doesn't have that power over humans in the same way. " ] }

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[ [], [ "https://www.youtube.com/watch?v=r6Rp-uo6HmI" ], [ "https://youtu.be/5zxVQBnmyDA" ], [] ]

{ "a_id": [ "ceu1pvo", "ceu51xd" ], "score": [ 3, 3 ], "text": [ "It's FM, and you know what happens to FM signals when 2 people try the repeater at the same time, with equal power. It's unreadable. Yes, the wifi points would jam each other too. \n\nThey can interoperate only because packets are short bursts and can be error corrected. They don't route the other networks traffic as it does not match their own essid. If you tried to operate demanding content on either, it would be a different story entirely. But just small amount of network traffic, you may only have a 20% duty cycle, so you can see with the ability to detect errors and resend, the only big challenge is to detect major packet collisions where headers are missing and you dont know who to send it back to. \n\nThis problem actually exists in networking without 2 access points as well. You would just need 2 users to feasibly create collisions. Well, that's where spread spectrum comes into play. That is above my level of understanding, but I believe it is correct to say the transmitters carrier frequency basically changes within the channel, seemingly at random and very often, and this change helps prevent collisions, but doesn't entirely eliminate them. Hence it does hurt performance but doesn't kill communication entirely. ", "First, I'm going to only talk about 802.11n in particular because I understand Orthogonal Frequency Division Multiplexing (OFDM) better than the other modulation techniques used; Direct-Sequence Spread Spectrum (DSSS) and Frequency-Hopping Spread Spectrum (FHSS). Though the underlying concept of DSSS and FHSS is more less the idea of a Spread Spectrum. Spread Spectrum more or less is making something that takes up very little bandwidth on its own take up more bandwidth to specifically prevent jamming or interference. OFDM is a little different though.\n\nOkay, with the fancy words out of the way lets define Multiplexing first. Let us say for example we want to build a road between two cities. One way to approach this might be make the road one lane allowing one car to travel on the road at any given time. While this car is traveling on this road no other cars are allowed to travel on it until it reaches its destination. After that another car going the opposite direction is allowed on. And so on and so on. In simple terms this is basically what Half-Duplexing is. It allows for communication two ways, but only one thing is allowed to communicate at a time. There has to be a more efficient way of allowing cars to get between the two cities, right? Another option we might try is a two lane road, we're spending the big bucks now. With this two cars can travel in different directions at the same time. More or less this is what constitutes Duplex communication. That is two devices can communicate with each other at the same time. But in those previous examples, only one or two cars are allowed to travel on the road at a time. Surely it can be made more efficient. Suppose we allowed multiple cars that are traveling in the same direction on the road at the same time, and that we further restrict them such that they are only able to travel in a single file line down the road at a fixed distance from one another. Ha! I think we have just crammed a ton of cars onto this road! If you think of each car being say a packet from the networking world then what that more or less describes is something called Time Division Multiplexing, though there is more to it. But this does not define Multiplexing. Essentially Multiplexing is taking a lot of individual . . ., channels of information and fitting, compressing, or aggregating (I like this word) onto a single channel of transmission. \n\nNow, with OFDM I'd like to focus on the last three letters first, FDM. FDM is Frequency Division Multiplexing. Going back to the idea of connecting two cities via a road. Instead of a single lane for each direction, why not add another giving a total of four lanes? What about making it six, or eight, or even ten?! Well we do have to draw a line at some point or another. With FDM what we do is take a fixed amount of bandwidth and divide it up into a set number sub-channels that do not overlap with one another. Depending on the selectivity of the filters, stability of the oscillators, and the actual modulation scheme used by the modems determines that amount of information that can be aggregated into a set amount of bandwidth. But Orthogonal Frequency Division Multiplexing takes this a bit further. Again going back to the road between two cities. What if we were to use twenty lanes, but we restrict the total amount of cars in any given lane to say five cars? Now, while a two lane road could handle the one-hundred cars, if some were to have tires blow out or engines blow up there would be less than one-hundred cars arriving at their destinations. If we imagine that these cars are imaginary bits of information that means we lost some. One way to combat the damaged cars causing any sort of back-up for flow of traffic would be to implement multiple lanes. This gives cars a way to go around the wrecked cars. Now, this does not fix the loss of information. To prevent the loss of information let us make every other car carry the same information. Now, imagine that instead of two lanes there are twenty lanes either way. Each of these lanes may not carry a lot of information individually, but together they carry a lot and they are very reliable in getting it where it needs to go. In a nutshell this is how OFDM works, in particular Coded OFDM which puts Forward Error Correction into the mix. That is take a small amount of bandwidth then modulate it onto several carriers at fixed intervals. But instead of putting the entire original signal onto each carrier; instead, we place only a small amount of the data present in the original signal onto each carrier. In effect what we have done is create a signal that takes up approximately the same amount of bandwidth and data rate as if we were to use a single-carrier transmission. The reality is that this OFDM signal has a multitude of sub-channels, where some are parallel to one another, and as a result has a lot of data integrity. In fact it is very robust to all sorts of signal degradation. Another way to think about OFDM if you're familiar with radios is like this. It can be thought of as a bunch of slowly modulated narrowband signals rather than a single large fast modulated wideband signal. \n\nThat was longer than I expected, but hopefully it should not have gone above too many people. I would definitely recommend reading the Wikis for pretty much all of these as the simplifications I did here are more for the sake of getting a basic idea. \n\n**Tl;Dr: Essentially, the signal itself has a lot redundancy built into it. This allows it to encounter some absolutely terrible conditions and still function properly. Albeit at a slower rate than in ideal conditions.**\n\nSource: Day job is Satellite Communications where we use a lot of these kind of things on a day to day basis. " ] }

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{ "a_id": [ "cky90fc", "cky9pmz" ], "score": [ 4, 2 ], "text": [ "On most boats, the rudder is, in fact, the principle steering device.\n\nThe sails on sailing vessels generally do not \"steer\" the boat. However, they must be re-positioned when the boat changes direction or when the wind direction changes, to maximize the thrust provided by the sails, using the available wind.\n\nFor non-sail vessels, there is often still a rudder, although steerable propellers or thrusters are often also used. Google \"Azipod\" and start reading, for more info.", "There are two modes of sailing, upwind and downwind. When sailing downwind the wind pushes the sail and the ship moves the direction it is pushed. The keel (or centerboard in a small boat) is important. It keeps the boat slicing forwards in the water, reducing side slippage. \n\nWhen you are traveling upwind the sail is acting like the wing of a plane, creating a low pressure area in front of the sail, which pulls the ship forward. The keel is really important when going upwind. \n\nWater flows along the keel and then hits the rudder. When the rudder is turned the water hits it and rotates the ship, turning the bow (front of the ship) in the same direction that the rudder is pointing. \n\nYou can steer a little with the sails if the rudder is broken, but you wont be able to point upwind at all. " ] }

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{ "a_id": [ "c89cn2q", "c89d30v" ], "score": [ 10, 41 ], "text": [ "[Here is a link to an article describing how they did the DNA analysis](_URL_0_) I will summarize it's points.\n\nThey were able to get a good sample of the corpse's mitochondrial DNA, which is passed without combination from mother offspring. Then, through a historical analysis, they found two people (currently living) who are descended, mother-to-mother, from Richard III's mother Cecily Duchess of York.\n\nThey compared the mitochondrial DNA of all three people and found them to be identical. So, what this proves is that these three people were descended from the same woman, and independent historical analysis pinpointed the common matriarchal ancestor of the two people living today as Cecily Duchess of York.\n\nSome additional evidence. \n\n- Radiocarbon dating suggested that the individual lived in the late 15th century\n\n- Bone composition suggested a high-protein diet including seafood, which would be expected for royalty of that time\n\n- The skeleton was from a slim man in his late 20s/early 30s (Richard III died at 32)\n\n- The skeleton had scoliosis, which is consistent with contemporary descriptions of richard\n\n- The skeleton showed multiple injuries, consistent with Richard III's death in battle", "You didn't really elaborate on what you mean, but I'm guessing you want to know how confident we can be that the skeleton they've found is King Richard?\n\nHere's an overview of the evidence:\n\nDNA comparisons:\n\n* Geneticists were able to extract and sequence mitochondrial DNA from the skeleton\n\n* Mitochondrial DNA is passed down from mother to child unchanged except for the occasional mutation\n\n* So, by comparing the skeleton's mitochondrial DNA to living people who descend from King Richard's mother's line along an unbroken line of females, we can see if the skeleton has the same mitochondrial group as what King Richard would be expected to have.\n\n* Genealogists were able to track down two direct matriline descendants of Anne of York (Richard III's sister) both of whom provided DNA samples for mitochondrial DNA testing. One of the descendants wants to remain anonymous. The second descendant is a Canadian by the name of Michael Ibsen. \n\n* The fact that they have two people means that they can compare them both and make sure that they match. It makes us more sure that we are predicting King Richard's haplogroup correctly because we can more safely say that there's no anomaly (such as an unknown adoption in one of the descendant's background).\n\n* The two descendants do indeed match, and they are members of a subgroup of haplogroup J. Luckily it is fairly rare, somewhere between 1 and 2 percent of the population belongs to this particular group. If the two living descendants were members of a very prevalent haplogroup, it would increase the odds that any match found between them and the skeleton would be purely coincidental. \n\n* Mitochondrial DNA comparison of the three people can be found [here](_URL_0_) -- it's a virtually perfect match.\n\nSo, that's the particulars of the DNA evidence that they have. However, there's additional evidence which makes them more sure that it's King Richard, and not some random haplogroup J guy:\n\n* Records say he was buried at a church in Leicester, 100 miles north of London. Archaeologist Richard Buckley identified a possible location of the grave through map analysis. They looked where his analyses predicted that King Richard would be, and they found the skeleton.\n\n* Radiocarbon dating estimates that the death occurred between 1455 and 1540 (Richard died in 1485)\n\n* The skeleton they found appears to have died in battle, and there's no coffin or anything like that, consistent with an enemy burial.\n\n* Various head injuries that the skeleton suffered are consistent with the way King Richard's death in battle was described\n\n* The remains display signs of scoliosis, consistent with contemporary descriptions of Richard. Other features of the skeleton are also consistent with Richard, such as the age. He died at age 32 and the skeleton they found died \"in his late 20s to late 30s\"\n\nThe DNA evidence alone or the circumstantial evidence alone would not have been enough to make a strong conclusion, but looking at everything together is pretty convincing. The research team is not saying that they are 100% sure they have found King Richard, but rather that they:\n\n > can now confirm that the body is that of Richard III \"beyond a reasonable doubt\"" ] }

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[ [ "http://www.washingtonpost.com/world/richard-iii-project-dna-pioneer-leicester-university-led-the-way-on-identification/2013/02/04/6c2081ec-6ef8-11e2-ac36-3d8d9dcaa2e2_story.html" ], [ "http://www.le.ac.uk/richardiii/science/resultsofdna.html" ] ]

{ "a_id": [ "cvgln73" ], "score": [ 7 ], "text": [ "They were a political party formed in the wake of public outcry over an incident where some Masons in NY state were accused of kidnapping and possibly killing at fellow Mason (named Morgan) who had published an expose on the initiations.\n\nThis was in the 1820s.\n\nThe Anti-Masonic party was the most successful third-party in US history, coming in second in a Presidential election!\n\nHowever, after the failure to win their bid for the highest office, the party began to unravel. The damage to Freemasonry being done, the party found that it was too divided to last.\n\nFreemasonry would not fully recover until later in the century during a period that lead to what's now called the Golden Age of Fraternalism, and spawned countless fraternities modeled on Freemasonry and also saw Freemasonry itself return to and in many ways surpass its former strength.\n\nThat period lasted until the early part of the 20th century, and the decline that followed (esp. during the depression) didn't rebound until after World War II." ] }

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{ "a_id": [ "cfibp3v" ], "score": [ 13 ], "text": [ "After the US colonized the Philippines the Catholic Church was disestablished, and was no longer the official religion. When that happened there was a large influx of Protestant missionaries of all denominations to the Philippines. Today, Protestants make up around 10% of the total population in the Philippines, with about 9 million people. While Protestantism was introduced to the Philippines during the period of US colonialism, it wasn't necessarily due to a push from the US government. It really was due more to missionaries acting opportunistically after the disestablishment of the Catholic Church. " ] }

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{ "a_id": [ "d6rfn91", "d6rftk7" ], "score": [ 2, 2 ], "text": [ "Meat from an animal that received high-quality feed is more chemically varied, and has more flavor. This is particularly noticeable in mild-tasting meat like chicken.\n\nHigh-quality beef typically has more fat mixed throughout (an effect called \"marbling\") which creates a richer taste and more delicate texture.", "It is a combination of several factors. Better quality meats will come from animals that were raised on better quality, more nutritious (and usually more expensive) diets. Genetics would have more to do with the actual build of the animal, but can affect quality. I also believe that the conditions that an animal is raised in can have a huge impact. (Think filthy, crowded feed lot VS. clean, spacious pasture)\n\nThe difference in taste and texture are a direct result of the way the animal is raised. What you put in is what you get out. Better nutrition = better building of the muscle fibers and more flavor." ] }

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{ "a_id": [ "c8rhmaa", "c8rhpgy" ], "score": [ 13, 2 ], "text": [ "In a nutshell, glass is very stable, and will not react easily with most compounds.\nThe class stays intact, the chemical stays the same, everyone is happy.\n\nHowever, some reagents are better kept in plastic containers such as polyethylene, or even quartz, because glass is not a magical non-reactive substance either.", "Borosilicate glass (the main kind of glass used in laboratory settings) is very inert towards the majority of reagents, even highly corrosive ones such as concentrated sulfuric acid. It also stable enough that it can be raised (and lowered) to a temperature range suitable for most reactions. Glass is not suitable for all applications, however, since some chemical, most notably hydrofluoric acid will etch glass or will otherwise compromise the integrity of glass containers. " ] }

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{ "a_id": [ "cnli5t7" ], "score": [ 2 ], "text": [ "It's random, mostly.\n\nPlate tectonics is driven by convection currents in the mantle under the crust. Most of the time, people only consider the major continents moving, but [the jigsaw puzzle is slightly more complicated](_URL_0_) than that. Numerous oceanic plates are jostling around too. \n\nDuring Pangea, Antarctica was wedged between India, Australia, and Eastern Africa. This whole assembly was around [the same latitude as modern day Southern Africa](_URL_1_). You'll see North America and Eurasia are up in the northern hemisphere, which is a good chunk of the land on Earth. \n\nAs things started to break up and migrate, Antarctica happened to get shunted south. Australia kinda followed it, these are the two landmasses that have been isolated the longest, but everyone else just sort of drifted north. The Northern Hemisphere is a lot more crowded land wise than the Southern, so it makes sense that the pole is more packed.\n\nThis was a bit rambling, but I hope it covered your question. tl;dr It's luck of the geologic draw." ] }

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[ [ "http://upload.wikimedia.org/wikipedia/commons/8/8a/Plates_tect2_en.svg", "http://3.bp.blogspot.com/-eB5sX6TtRs8/UldIxYgl2wI/AAAAAAAADak/CAbc9wQ-_t8/s320/continente.jpg" ] ]

{ "a_id": [ "c69vc1s", "c69x1q8" ], "score": [ 8, 2 ], "text": [ "No. There's a very critically timed cobination of events that have to happen to get a nuclear detonation. The worst that would happen is that you detonate the charge around the fissile material and produce a conventional 'Dirty' bomb.", "Yes it can and it is already used! (kinda)\n\nIt all depends on the size kinda....\n\nA standard nuclear fission bomb explodes because of massive ammounts of (normaly) uranium receiving neutrons which causes them to become unstable and splice. With this fission you will get lots of energy and a could of extra neutrons to boot to keep a chain reaction going.\n\nUranium normal has some spontanious decay going on which might trigger a spontanious chain reaction. If you have sufficient uranium, this spontanious chain reaction can only happen if the uranium is very pure and if you have enough material (+/- 2.5 kilo). \n\nA slow chain reaction is used in nuclear reactors to power turbines and can be used to generate electricity.\nA faster uncontroled chain reaction is called a meltdown where more heat is generated then the cooling systems can handle (see Chernobyl disaster).\n\nNow for the question:\nIf you manage to have a large ammount if uranium which is already close to critical mass, you can set it off if you give it a sudden boost of massive ammounts of neutrons. This boost you can give with another nuclear explosion.\n\nA hydrogen bomb (more powerfull version of the fission bomb) uses not fission (big unstable atoms into smaller atoms) but fusion (merging of small lighter attoms into more heavier atoms).\nA hydrogen bomb uses a heavy version of hydrogen (called tritium) and the chain reaction is also started by massive ammounts of neutrons! \n\n\nSo, wrap a 'standard' fission bomb with large ammounts of heavy hydrogen = > Set of the fission bomb to get explosion with large ammounts of neutrons - > Neutrons start of fusion in the heavy hydrogen = > even bigger explosion!!!\n\nSo yes, a hydrogen bomb is set of by a primairy A-bomb explosion.\n" ] }

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{ "a_id": [ "c2t3jjg", "c2t3r1j", "c2t3jjg", "c2t3r1j" ], "score": [ 3, 2, 3, 2 ], "text": [ "short answer to your question can be: because there is no matter with negative mass.\n\nall matter has positive energy (this statement is called \"weak energy condition\") and creates positive curvature of spacetime (positive and negative are subject to sign convention). effect of this \"positive\" curvature is, that when you move forward in time, it acts as attracting force. you can imagine it like two people starting at the equator and going toward pole - they come closer to each other just as if there was some force that pulls them together, but in fact, they are only changing one coordinate (in real case it would be time coordinate) ( < - this was an EDIT2).\n\nin theory, you can invent metric (metric describes the curvature of spacetime) that has negative curvature on some places in space and positive on other ones. those metrics can have really cool properties. some are described as \"wormholes\" some other as \"warp bubbles\", but the problem with all of them is, that they would require this matter with negative mass (also called exotic matter). we have no evidence of such a thing.\n\nEDIT1: also, there are some issues with mathematical structure of the equations that describe gravity (einstein equations)...\n\nEDIT3: google up \"energy condition\"", "I'm struggling to think of any forces that have opposites - certainly none of the 4 fundamental forces do: Electromagnetism is directional, but there's no opposite. Strong nuclear, and weak nuclear have no opposites.", "short answer to your question can be: because there is no matter with negative mass.\n\nall matter has positive energy (this statement is called \"weak energy condition\") and creates positive curvature of spacetime (positive and negative are subject to sign convention). effect of this \"positive\" curvature is, that when you move forward in time, it acts as attracting force. you can imagine it like two people starting at the equator and going toward pole - they come closer to each other just as if there was some force that pulls them together, but in fact, they are only changing one coordinate (in real case it would be time coordinate) ( < - this was an EDIT2).\n\nin theory, you can invent metric (metric describes the curvature of spacetime) that has negative curvature on some places in space and positive on other ones. those metrics can have really cool properties. some are described as \"wormholes\" some other as \"warp bubbles\", but the problem with all of them is, that they would require this matter with negative mass (also called exotic matter). we have no evidence of such a thing.\n\nEDIT1: also, there are some issues with mathematical structure of the equations that describe gravity (einstein equations)...\n\nEDIT3: google up \"energy condition\"", "I'm struggling to think of any forces that have opposites - certainly none of the 4 fundamental forces do: Electromagnetism is directional, but there's no opposite. Strong nuclear, and weak nuclear have no opposites." ] }

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{ "a_id": [ "e1srqez" ], "score": [ 10 ], "text": [ "The idea is a debate about whether the founders wrote the thing to be specific, rigid, and amendable only through the amendment process...\n\nor whether the founders wrote the thing with deliberately looser language to take shifting societal norms into account.\n\nFor example, the 8th amendment prohibits \"cruel and unusual\" punishments but neglects to define those terms. An originalist would argue that we need to research what \"cruel and unusual\" meant to the founders. A proponent of living document theory would argue that \"cruel and unusual\" is deliberately vague so that the boundaries of cruel and unusual can shift as society progresses." ] }

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{ "a_id": [ "cbuylm1", "cbv5sdn" ], "score": [ 6, 7 ], "text": [ "Slaves in Greece were not a rare thing to see. It is certain that rural slavery was very common in Athens. It is estimated that every citizen in Athens had at least 1 slave so, to answer your question, high class people were not the only ones to have slaves.\nA slaves principal use was for agricultural purposes usually but if there was a wealthy slave owner with dozens of slaves then there would be a foreman who oversaw all responsibilities of the other slaves. I haven't heard that slaves were \"in the family\" but you thought right when you questioned whether they do no manual labor. ", "It's a simplification, and simplifications like this are only going to make sense with respect to some benchmark; perhaps that's the context of your friend's view. But without context, there isn't really much to support her.\n\nEstimates of the slave population in Classical-era Greek states are exactly that, estimates, but those estimates normally range between 60% and 80% of the total population. One census reported from the late 4th century BCE would put the figure at nearly 87%. Even if we're sceptical of that figure, it's still a *lot* of slaves.\n\nSome did serve functions as valets, child-minders, scribes, and so on. These ones certainly fit your friend's model. But you don't have to look far to find slaves in manual labour. There were also public slaves, responsible for things like cleaning up obstructions and large messes in the streets: so far, not too bad. But an awful lot of farmwork was done by slaves, and it's much harder to believe that they led a happy fulfilling life.\n\nAnd there were some really awful slave positions around: for example, in Athens the silver mines at Laureion were worked exclusively by slaves, precisely because conditions were so appalling that any worker would have a pretty short lifespan after going there. Tens of thousands of slaves worked the mines, because the mines were so lucrative for Athens, and because slave-owners could actually lease unwanted slaves to the mines for a steady income. In Sparta things were even worse in a way, though perhaps not as intensely awful as silver mining: every year the ephors would ritually declare war on their helots, there were occasional mass slaughters, and adolescents were trained to go stealing and killing among them. Slaves could also be recruited for warfare: both Athens and Sparta used slaves in this way (though their treatment of the slaves afterwards varied a lot: after the naval battle at Arginousai, Athens officially freed all the slaves who had fought in the battle; in Sparta, a group of troublesome helots who had served in battle were rounded up under the impression they were going to be freed, and then slaughtered).\n\nSlaves had no rights and could be tortured, deprived, and killed without recourse (the only limit was on doing these things to *someone else's* slave). When testifying on a legal matter, slaves' testimony was only valid if extracted under torture. So sure, *some* slaves had cushy positions. But it's certainly not a lot that I'd choose." ] }

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{ "a_id": [ "cx5w03h", "cx6cu62" ], "score": [ 3, 2 ], "text": [ "Been asked before a few times. The term for this is [Single Combat](_URL_0_).\n\n_URL_1_\n\n_URL_2_", "I've talked about this wrt feudal Japan [here](_URL_0_). Also, a more common thing seen pre-Sengoku era was still duels between opposing soldiers, though not in the sense of 'champions' but rather pairing off two sides during the battle." ] }

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[ [ "https://en.wikipedia.org/wiki/Single_combat", "https://www.reddit.com/r/AskHistorians/comments/183dk7/are_there_any_cases_where_two_leading_individuals/", "https://www.reddit.com/r/AskHistorians/comments/1f46ls/at_the_beginning_of_the_film_troy_a_battle_wasnt/" ], [ "https://www.reddit.com/r/AskHistorians/comments/3j92pc/its_common_in_historical_fiction_for_leaders_of/cunpmqn" ] ]

{ "a_id": [ "cd6qxkt" ], "score": [ 7 ], "text": [ "**First the basics:**\n\nDifferent languages have different phonetic systems (where phonetics refers to the individual consonant vowel combinations that form the phonemes which establish contrast for word differentiation. You know \"bat\" and \"pat\" are different words because [b] and [p] are \"contrasting\").\n\nThe primary factor that differentiates languages is the vowel inventory of that language (I say vowels as primary because they are \"sonorant\" or sound creating whereas consonants like \"stops\", \"labials\" and \"fricatives\" are the continuation of sound or the stoppage of sound). English has the basic vowels of /a/, /e/, /i/, /o/, and /u/ (the orthography I'm using to describe the vowels is not standard IPA. I decided not to spend the extra time typing it all out). You then have dipthongs, which are the vowel sounds created by adjacent vowels. You then have, to a lesser degree your allophonic dipthongs and vowels based on the surrounding consonants (a /a/ sound is going to sound slightly different if it's next to a [b] as compared to an [sp]).\n\nThe native speaker perceives and produces language given the above criteria.\n\n**Now to apply this to a second language learner:**\n\nThe native German speaker who is learning English has DIFFERENT vowels than you as a native English speaker (different consonants as well, but the vowels are easier to recognize). As a native English Speaker, you have your inventory of English Vowels. When you listen to the native German speaker who has acquired English as an adult (as opposed to the bilingual, young child between 4 to 7 who has the opportunity and the language acquisition mechanisms to acquire \"native fluency\"), you are listening to the cross-influence of the native German speaker's German vowels and his attempt, successfully or otherwise, to produce English vowels. The \"accent\" you hear is thus your ability to pick up the difference in vowel quality.\n\n**What about the consonants?**\n\nConsonants likewise have an impact on how the vowel of the speaker is formed. Vowels, as mentioned before, are sonorant and the quality of the vowel is thus determined by multiple different factors: elevation of the tongue in the mouth, the \"frontness\" or \"backness\" of the tongue (is the tongue closer to the teeth, is it further away from the teeth?), and the shape of the lips. The mouth is thus an acoustic chamber that changes the sound of the vowel based on its shape. Just like for vowels, different languages have different consonants. While the different consonant inventories is obviously a part of the equation, it would have, comparably, lesser impact as most consonants in a language \"stop\" sound as opposed to create sound.\n\nAn oft used example of how consonants impact the accent is when you compare most Asian languages to that of English. Japanese and Chinese are notorious for not having the [r] that's native to English. They instead of what is called a \"flap/tap\" (the same sound you hear when someone says the word /button/ which only occurs word-medial or in the middle of the word). The Japanese or Chinese speaker in most instances does not have the muscle control and dexterity to move the tongue into such a position as to produce the [r] so they instead produce an approximation of the consonant [ɾ]. They approximate the sound by substituting a sound that is produced most similar in tongue positioning. The end result is \"rat\" sounds like \"lat\"." ] }

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{ "a_id": [ "e3bnr0o" ], "score": [ 11 ], "text": [ "You usually just take regular atoms and rip off their electrons somehow (heat them up, subject them to strong electric fields, shoot them through stripper foils, or some combination of those)." ] }

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{ "a_id": [ "d4ti0rx", "d4ti2mz" ], "score": [ 4, 4 ], "text": [ "A laser tends to be very well focused, which means that its energy doesn't spread out that much as it travels. A flashlight, on the other hand, isn't focused that well, which means that its energy spreads out very quickly as it travels, so gets dimmer much faster than a laser does.", "Lasers are a continually beam of powerful light (which is why you should never stare into one). The particles that make up the light are tightly focused and less likely to disperse. Flashlights however shoot in a cone shaped beam which spread out and eventually become invisible to the naked eye. " ] }

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{ "a_id": [ "cgsgwfa", "cgshw8c", "cgsibxu" ], "score": [ 2, 2, 13 ], "text": [ "momentum, jumping with two legs slows you down to an extent", "because you're using your other leg for momentum.", "Well, it's not all about raw power. The problem isn't being able to move upwards, you can climb stairs a lot higher than you can jump. The problem is accelerating quickly.\n\nLook at it this way; stand perfectly still with your hands at your sides and jump. \n\nYou probably didn't get very far. This is because when you jump off one leg, neither your arms or your extra leg is sitting as dead weight. Your body spends a great deal of energy to thrust them upward just before you leave the ground. There's a lot of weight in a leg, so the inertia from that plus your arms all being thrust upwards helps to accelerate the actual dead weight (the rest of the body). \n\nTake for instance [this tornado kick](_URL_0_ ). The person in the gif appears to exert very little force on the ground as they lift off. This is because they slowly build up momentum leading up to the jump (by spinning) then angle that energy upwards to carry them off the mat.\n\nBasically the idea is rather than pushing yourself up with two legs, you're pulling yourself up with the momentum you built up in your swinging arms and legs." ] }

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{ "a_id": [ "ccjiwlb", "ccjix2k", "ccjj7qq", "ccjjedw", "cck54cr" ], "score": [ 10, 7, 5, 2, 2 ], "text": [ " > How does one shot protect you from all variations of flu?\n > Do they need to be topped up, as newer strains come into existence?\n\nOne shot contains vaccines for three different strains of flu. The CDC spends a LOT of time and effort every year trying to predict which three strains are most likely to be a significant health threat that year, and do so with enough lead time to get the vaccines produced and distributed.\n", "The flu vaccine contains pieces of the outer proteins of different influenza viruses. When they are injected, cells in your body eat these proteins, digest them, then present little fragments of them to T and B cells. T and B cells that have a receptor that recognizes the flu proteins then multiply. The flu specific T and B cells then develop memory of the flu proteins. If you become infected with influenza, the T and B cells that were primed by the vaccine begin to combat the infection much earlier than would happen if you had to develop these cells at the time of your infection. It does not prevent infection in humans, but it can shorten the time you are sick and the severity of the infection.\n\nSource: I work on flu in an immunology department.", "My grad school work was in the lab that produced the seed strain for the Influenza B part of the vaccine, and my thesis was on adapting the reassortment process used to produce high yield strains of A to the B virus.\n\nThe annual vaccine is trivalent, containing one strain of B and two of A. Every spring, there is a meeting, where the committee looks at what's circulating globally, and make an educated guess as to what might hit in the US next winter.\n\nThen, they collect samples of those strains, send them to labs, like the one I worked in, and we would try to adapt them to grow well in eggs. Once we were done, we would send vials of frozen seed to the vaccine manufacturers for scale up and production.\n\nOften, there isn't much change between one year and the next, and the vaccine will give protection over multiple years, but eventually, it will mutate enough to be not neutralized by antibodies to the old strains. ", "Very simplified:\n\nInfluenza (disease) is caused by certain influenza viruses of the orthomyxoviridae family, and they are categorized into three categories or \"species\": influenzavirus A-C. \n\nThere are however different subtypes of each virus species. \n\n\"Flu shots\" often includes pieces of viruses or killed/weakened viruses and are aimed to trigger an immune response without causing sickness.\n\nThe immune response, if successful, will generate antibodies against the foreign objects injected to the body which will render them harmless. The most important cells for prolonged immunity are the white blood cells called \"B-cells\" which works as a memory to almost instantly react and prompt the production of antibodies if the body is exposed to the same virus again. \n\nSome flu shots include pieces from different influenzavirus subtypes and thus grant \"immunity\" to those. When a new influenza virus emerge it's of great importance to quickly find and extract pieces of this virus and check if it could potentially stimulate the immune-system to create antibodies that can \"stop\" the virus.\n\nSome viruses, however, are very hard to find vaccines against due to the nature of the virus (HIV for example).\n\nSource: Pharmacology student, and some Wikipedia (to refresh memory) ", "Most flu comes from 2 sources (I live in the UK but it should be similar in the states) birds which migrate and pigs. \n\nThey basically take samples from these 2 sources and try and look at which strains of flu are likely going to happen that year. Bearing in mind they have to manufacture millions of flu vaccines they need probably at least 6 months+ to do this.\n\nEvery year you have a flu jab but its to different strains." ] }

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{ "a_id": [ "d15aysl" ], "score": [ 22 ], "text": [ "Swedish M26 Army Helmet seems to be the one, \n_URL_0_\n\nHeres some info on it. \n\n_URL_1_" ] }

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[ "http://imgur.com/a/YdWYV" ]

[ [ "http://nuke.combat-helmets.com/Portals/0/2010/SweM26-65a.JPG", "http://forum.axishistory.com/viewtopic.php?f=8&amp;t=129470&amp;sid=b22be6cd242320fa9b5210b97804bf97" ] ]

{ "a_id": [ "cqxrya6", "cqxx0zl", "cqy3bt9" ], "score": [ 100, 8, 3 ], "text": [ "The modern human gastrointestinal tract is evolved to digest cooked food. That takes a long time. Here is a peer reviewed article that argues that control of fire was achieved nearly two million of years ago by some of the first members of the Homo genus:\n\n_URL_2_\n\nBecause of the time needed for our current digestive systems to have evolved and also corresponding archeological evidence of controlled use of fire (ancient radiomatrically dated firepits) it's now the general consensus that control of fire (and it's use for cooking) must have occurred no earlier than 400,000 years ago:\n\n_URL_1_\n\n_URL_0_\n\nIrrefutable evidence of cooking fires has been dated to 125,000 years ago. But this is not really a possible timeline for when control of fire began due to the evolutionary evidence of our guts: Our species, Homo sapiens, must have evolved in a population that had control of fire and used it to cook food, which means control of fire and cooking must have begun half a million years ago at the earliest.\n\n\nEdit:\nIt's impossible to answer the second part of your question. Humans would have experimented with cooking the variety of foods available. I don't see how you could get a specific timeline of the integration of spices and other cooking ingredients; it would all be highly variable and probably a subject of debate with many of the wild varieties. For instance we have no idea when humans started eating garlic, it's really difficult to get an accurate date of pre modern (read pre writing) things like this.", "I'm on mobile so no links, but Richard Wrangham, who is an anthropologist, has an entire book on this, called Catching Fire. \n\nHis main argument boils down to 2 million years ago. I think that's probably too long ago, but the book is very enjoyable and well written, save for the one chapter on sex and division of labour, which rankled.", "Great discussion going on. I have often wondered about this so I'll piggy-back this topic (since it is very related) to ask the following:\n\n\n\nI can't wrap my head around making the leap from controlling fire, to cooking food.\n\nIt would make sense that once early man had control of fire that he would start experimenting. Putting anything and everything he could into the fire to see what would happen. So naturally at some point he would stick some food in there and cook it by accident.\n\nAnd maybe then he would eat it and it would have been more nutritious. But of course he couldn't have known it was better for him. An animal used to eating raw meat and vegetables wouldn't automatically think that cooked food was better would it? Especially to the point that cooking it was universal thus guiding our evolution.\n\nNot that I'm doubting that that leap was made, i just don't myself understand it." ] }

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[ [ "http://discovermagazine.com/2013/may/09-archaeologists-find-earliest-evidence-of-humans-cooking-with-fire#.UpHIM2tYCSN", "http://www.sciencedaily.com/releases/2012/04/120402162548.htm", "http://faculty.ksu.edu.sa/archaeology/Publications/Hearths/Hominid%20Use%20of%20Fire%20in%20the%20Lower%20and%20Middle%20Pleistocene.pdf" ], [], [] ]

{ "a_id": [ "cxsal8i" ], "score": [ 15 ], "text": [ "*I speak of the Middle Ages.*\n\nIslam doesn't really have monasticism. Within Sufism, Islam's mystical tradition, we can see some parallels to Christian monasticism, but fundamental differences remain--they are, at heart, different institutions with different roles to play in their respective religions and societies.\n\nAccording to Christian tradition, the roots of monasticism lie in the late antique Egyptian desert, where so-called Desert Fathers (and Mothers!) were inspired to (in theory) leave \"the world\" behind, and move into isolated (in theory) caves or rough buildings to focus on their spiritual lives and relationships with God. Two things happened: one, they were seen as holy and people from nearby villages/cities came to them seeking advice and consolation. Two, they started to form their own communities. First, communities of hermits who sometimes came together; eventually, communities who devoted as much time to seeking God *as a community* (in group prayer) as on their own. And, eventually, these communities developed formal Rules to regulate their daily lives.\n\nThat is what we typically mean by \"monasticism\" in Christianity: a group of people, typically single-sex (although \"double-houses\" of women and men, isolated from each other but living side-by-side, are a western medieval thing in certain times and places), who swear permanent vows of poverty, chastity, and obedience; wear a uniform; and follow a rigid daily schedule of group prayer, individual prayer, and some amount of time for work. \n\nAs a social institution, monasteries own land, play power politics, are played with *in* power politics among bishops and secular lords (donating land to a monastery to keep it out of someone else's hands), offer a place for noble and royal widows to finish out their lives without needing to remarry (and thus preventing their lands from leaving the family), provide charity, and intercede between their patrons and God. In the early Middle Ages, monasteries were *crucial* in spreading and anchoring Christianity across pagan Europe. They were centers of learning, literacy, and libraries throughout the medieval world. As a religious institution, monasteries allow monks and nuns to nurture their inner spiritual lives--Christian mysticism largely, though not exclusively, comes out of the monastic tradition.\n\nSo in Christianity, mysticism tends to emerge from monasticism, or is just one part of it. Conversely, Sufism is the inner or mystical dimension of Islam, and in some cases, we can see some parallels to monasticism within that mysticism tradition.\n\nThe Sufi tradition generally consists of disciples or students under a leader. As you might expect, this idea of a teacher with a group of students, appointing one as their heir upon their death, does lead to the development of *tariqa* or orders of Sufism. \n\nUnlike the rigid, exclusive, vowed communities of monasticism, however, Sufi orders are fluid. People can join them, leave them, adhere to multiple traditions at the same time! They are collective teachings of ways to build your individual relationship with God. The Christian monastic orders can also be seen that way, but they are exclusive, for-life, and consider the full way of life as part of building that relationship.\n\nAdherence to Sufi orders can manifest in many different forms. In some cases, particularly in north and west Africa, where an entire people or branch of a people will follow Sufi principles. Some Sufis will live independently and come together or meet with the teacher. But in other cases, we do see Sufis living in community. I stress that this is not the formal vowed life under a Rule of Christian monasticism. Neverthless, *zawiya*/*tekke*/Sufi \"lodges\" of the Middle Ages resemble their Christian counterparts in some ways.\n\nStructurally or architecturally, the zawiya complex provided lodging for their Sufis, a school (zawiya simply means madrasa/religious school in some parts of the Arab world), space for daily prayer, and sometimes institutions like lodging for visitors or hospitals for the sick and indigent. You would find equivalents for all of these in medieval Christian monasteries! Zawiyas, though, reflected Sufism's individualistic focus much more than their Christian counterparts tended to. While most Christian monastic traditions did not allow individual cells or space for private prayer until later in the Middle Ages (Christianity also has an eremetic or hermit tradition, though), Sufi zawiyas frequently offered both. And again, vows and the rigidity of monastic Rules were not part of life in a zawiya.\n\nSufi zawiyas did, however, mirror Christian monasteries in their missionary function. Both individual Sufis and established zawiyas played crucial roles in the expansion of both Islam and literacy in the early medieval (and also rather more modern) world.\n\nIslam and eventually Sufism are born and cultivated partially in lands very familiar with either western or eastern forms of Christian monasticism--including, of course, the Egyptian desert itself. Were the Sufi zawiyas inspired by the Christian monastic communities their founders were well aware of? Was it simply the case that the medieval Mediterranean world shared enough circumstances that educated religious communities as beacons of charity and missionary work filled a necessary niche in both? Or was it a mix of the two? As you can imagine, influences between Christian monasticism, Sufi zawiyas, and the mystical tradition within the two religions (and Judaism as well) remains a rather hotly debated question.\n\nOverall, it is wrong to say medieval Islam developed monasticism. But a closer look reveals that within Sufism, institutions did develop that paralleled contemporary Christian monasteries in several important respects.\n\n*My apologies for not including the Buddhist, Hindu or Jain monastic traditions in this discussion.*" ] }

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{ "a_id": [ "cynm0iz" ], "score": [ 4 ], "text": [ "My own area of study is the armour of high and late medieval Europe. So my answer will focus on that, not on the Early Middle Ages. I mention this caveat because the economics and social organization of Europe were very different between 600 and 1450, and this effected things like how armour was made, which in turn effected the time it took to make it.\n\nMy source for this is Alan Williams' The Knight and the Blast Furnace.\n\nA mail shirt might have between 28,000 and 50,000 links, depending on the size of the links and the length of the skirt an sleeves. Some mail was made of alternating riveted and solid links (IE, something like a washer). This was quicker to make, and modern estimates suggest it would take around 750 man-hours to manufacture. If a single laborer worked 10 hour days, this would take 75 days to make (not including sundays and feast days). However, laborers often didn't work alone, and workshops would include division of labor to speed up the process. So the actual time to manufacture a shirt would often be less than 75 days, even if it represented 750 hours of labor - how many people worked on a shirt, and how well they collaborated would determine the actual time of manufacture.\n\nFrom the 14th century onwards, mail is increasingly made of all rivetted links, perhaps because it allows a tighter weave with thicker links and thus makes mail more protective. Rivetting all those extra links would add around 250 man-hours of labor, for a total of 1000 man-hours.\n\nThis made mail rather expensive, as you can imagine. In the beginning of the 14th century mail shirts bought in Bruges in Flanders were the equivalent of 60-130 days wages of a common soldier on campaign. In the early 15th century mail shirts bought from the Westphalia region of Germany were the equivalent of around 25 days wages, which is a good deal more affordable. At least some of this reduction in price may have been due to the re-use of mail - mail is easy to recycle, alter, cut up and repurpose. Many surviving mail shirts shows signs of alteration from decades or more after they were first made, and smaller pieces of mail armour like standards (collars), sleaves, skirts and gussets (underarm guards) may well have been made from older mail shirts that were cut up. So a lord buying mail shirts for his retinue might not be buying new mail, but 'remanufactured' mail.\n\nAs a final aside, the first step to making mail is making some form of wire or at least some thin piece of metal that can be bent into a ring. The quickest way to do this is to draw it - basically pulling an iron rod through a series of hole in a 'draw plate', creating a wire of a given thickness. This process is first mentioned by Theophilus in the 11th century, but mail with links of fairly even thickness dates as early as the 8th century. Some medieval mail is made from 'wire' of less even thickness, which may have been made through other processes like cutting strips from flat pieces of metal and then twisting them. I mention the manufacture of wire because while it isn't included in the calculations above, it is important to keep in mind that this was labor that needed to be performed before mail could be made - even though it wasn't necessarily performed in the mailmaker's workshop by the mailmakers themselves. Improvements in making wire made mailmaking faster and mail more affordable.\n\nEDIT: A final note is that mailmaking and making plate armour were different crafts, and at least in larger cities like London were represented by different guilds.\n" ] }

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[ "https://www.youtube.com/watch?v=CdqOE_OHEP0" ]

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{ "a_id": [ "cxnlift", "cxnljyq" ], "score": [ 3, 2 ], "text": [ "In most cases where facilities were built by the public and then privatized, the company either had to pay the government for the facilities, or agree to repair or improve the facilities at their own expense, thus effectively paying a bill that would have been the government's bill.\n\n", "You have to pay the provider of the service. Water, electricity, etc. cost money to extract/generate and transmit. You have to pay FedEx to drive your packages down the highway even though the highway was built with taxpayer money, right?\n\nAs to your other questions about utilities industries, they're complicated and state-specific. In general, it can be anything from a free-for-all where anybody can become, for example, a competitive retail electricity provider, or it can be state-sponsored monopoly where the government gives one private company the exclusive right to provide the service in a particular area. " ] }

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{ "a_id": [ "cclokuo", "cclprcr", "cclqdad", "ccltsco" ], "score": [ 9, 2, 9, 2 ], "text": [ "Because the challenge is gone. \n\nPossibly. ", "This reminds me of the last scene in Zero Dark Thirty (I'd say spoiler here, but since the film was based on recent real-life events, you probably know the plot already.)\n\nIf you've devoted a significant amount of time to something, once you complete it, your primary purpose is gone. It takes a bit of time to find a new goal.", "I feel that way too. For me I'm pretty certain it's just a lack of self-confidence. By completing the task, I haven't proven that I can do something difficult; either I didn't really earn it for some reason, or I've shown that it wasn't really difficult in the first place.", "The challenge or goal is gone and now that you have overcome it, you don't know what's next. Now you are empty as you await for another goal to approach itself so you can have the same feeling. Completing goals is good, having goals is good. Having too many goals is stressful, having no goals makes you feel useless and empty. " ] }

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{ "a_id": [ "c7dcfqm", "c7ddq0k" ], "score": [ 9, 7 ], "text": [ "[They can help reduce indoor pollutants](_URL_0_)", "Houseplants can provide numerous [mental health and psychiatric](_URL_0_) benefits." ] }

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[ [ "http://www.sciencedaily.com/releases/2009/11/091104140816.htm" ], [ "http://library.wur.nl/frontis/farming_for_health/04_elings.pdf" ] ]

{ "a_id": [ "c7mdt9d", "c7me061", "c7mfhud", "c7mibe5", "c7mqvif" ], "score": [ 34, 3, 14, 9, 3 ], "text": [ "First of all, the Germans never used the word 'Blitzkrieg' themselves and did not have a specific doctrine around deep penetration or strategic battle - as you can see from from them turning back from Warsaw to deal with the Polish counterattack at Bzura 1939-09-09, the halting of the armoured units in front of the Dunkirk pocket 1940-05-17 and 1940-05-24 and diverting the armoured units from *Heeresgrupp Nord* and *Heeresgruppe Mitte* to help form the Kiev pocket 1941-09-16.\n\nThe Germans had a strong tactical focus, with their *auftragstaktik* and were extremely flexible tactically, allowing them to penetrate enemy lines and advance on the depth. However, they did not have any specific strategic doctrine other than the traditional military ideal of the dual pincer cut-off, famous ever since Hannibal did it in the Battle of Cannae. \n\nThe Germans never managed to get mroe than about 17% mechanisation of their forces - most marched on foot and pulled their heavy weapons with horses, and the difference in speed of these two different kind of units was a constant headache, and was exploited by the allies and Soviets multiple times. As the German armoured units attacked the suburbs of Warsaw 1939-09-08 (losing 70 tanks in the process and learning that tanks were not very good in urban warfare), the untouched Polish Poznan and Pomorze armies gathered at the Bzura River and attacked the German *30. Infanterie-division* that was the only stretched-out flank protection of the German advace. The Germans had to pull back from their attack of Warsaw, go after the Poles and the campaign lasted for another two weeks.\n\n**In essence, the Germans had no blitzkrieg, they were flexible tactically and strived for encirklement strategically, and had severe problems with the armoured and motorised units outrunning the foot infantry.**\n\nThe Soviets did develop a doctrine of deep penetration, but essentially abandoned it during the 1937-1938 purges. While the purges mostly killed off generals and colonels and left the non-senior officers in place, it did freeze the Red Army in place. No-one dared do anything without orders, and tried to replace tactical flexibility with zeal and discipline, which was a recipy for disaster - which the defeat of the Spanish Republican Army (organised along Soviet lines in late 1936 and early 1937) and the performance of the Red Army in the Finnish Winter War 1939-1940 and early in the Great Patriotic War 1941-1942 shows.'\n\nThe Red Army slowly got better at knowing what it was good at and what it was bad at, and how to use what it was good at and compensate for what it was bad at. It created massive breakthough artillery units, shifting them to where they were needed. They knew they could never match the Germans in tactical flexibility, and instead created an operation doctrine, where they would rely on firepower of pre-calculated artillery barrages and massed use of tanks and assault guns to achieve penetration of the enemy lines. Massive reserves would be ready to attach to any attack that showed promise, and attacks that failed was stopped and their best forces moved to reinforce the attack that did well. Once penetrating, the Red Army focused more on destroying the enemy supply, communication and weaker rear units (destroying tank repair shops, supply services, traingin depots, etc.) and capturing important transportation hubs. Other so far untouched enemy units would be forces to retreat to not be cut off, and once out of their entrenchment and unprotected by artillery, they could be an easy prey for another massed attack. Flexibility on a larger scale, it was very effective against the Germans once their ability to conduct large scale armoured warfare had been ground down. The skill in *maskirovka*, the art of camouflage, hiding own forces and making it look like there were substantial forces where there were almost none was also important. The Red Army mastered this art.\n\n**In essence, the Red Army could not match the Germans in tactical skill, and thus built up flexible reserves to quickly shift to any breakthrough. Combined with *maskirovka* this allowed them to decisively defeat the Germans on the eastern front.**", "Both feature combined arms at their core and seek the dislocation of enemy forces through superior mobility, but Blitzkrieg has a tactical focus whereas Deep Battle takes the concept to the operational scale.\n\nYou might want to qualify your question with a temporal frame : Blitzkrieg came to its peak during the spectacular German conquests whereas the maturing of Deep Battle was just starting. While Tukachevski & al. did conceptualize Soviet operational art in the thirties, it is really the brutal and costly experience of WWII that hammered the concept into the shape of an efficient doctrine - see operation Bagration for a summary of that crazy learning process.\n\nI'm posting from memory on a mobile - I'll fetch some sources when I come home to a proper workstation.", "Theoretically, the two approaches are different styles of surface-and-gap warfare. Which basically says, attack the enemy where there is a gap (weakness) in his forces rather than a surface (strength).\n\nThe Germans exploited gaps through recon-pull, the Soviets used command-push.\n\nThe Germans would send out recon units to find weak spots, and flex their main effort formations to take advantage of and break through them. **Recon** units found the gaps, and **pulled** the main forces after them through the gap to exploit the enemy's rear--encircle him, shoot up his logistics, etc.\n\nThe Soviets would say, \"I vant gap here,\" and point to a spot on the map, and they would mass their artillery corps to blow a hole in the line. The **command** created a gap through overwhelming firepower, and **pushed** their forces through it.", "[I drew you a crappy representation of Blitzkrieg versus Deep Battle in MS Paint.](_URL_0_) The graphic you have about Blitzkrieg is different from my understanding of that strategy. My understanding is that, typically, Blitzkrieg attacks at one main point, punches a hole in the lines, and then seeks to effect envelopments/encirclements as the opportunity arises. For instances, punch a hole in a north-south defensive lines, drive deep, and then wheel around either to the north or to the south to create an envelopment around whichever part of the defenders a general chooses. This is in contrast to the dual pronged attack that is pictured in your graphic. Therefore, my representation looks a bit different from yours. (This is not to say that either is the only right representation!).\n \nBased upon my understanding, the big difference between Blitzkrieg and Deep Battle is that the former identifies a weak spot from the get-go, and then seeks to exploit it based upon a singular assault, whereas the latter does not target an existing weak point, and instead seeks to create many weak points through sheer brute force along several points of attack, then push deep to destroy supply lines and create envelopments. Also, it seems to me that Blitzkrieg is somewhat on a smaller, or at least more targeted, scale, whereas Deep Battle is an incredibly broad and huge strategy that requires massive manpower. Somebody correct me if I'm wrong.", "A little late to this I see, but I still wanted to share my own perspective- and also attempt to clear up some misconceptions, before I start though – apologies for a longish post, but Military history is my passion, and WW2 OST front is an all consuming passion ;)\n\nThere is a substantial difference between “Blitzkrieg” – the term itself did not exist in the lexicon of the Wehrmacht and Deep Operations, and the difference stems largely from the unique constraints and strengths facing both these nations.\n\n**Background:**\n\nThe Russian army has historically fought (and mostly won) defensive campaigns, using the space of Russia to draw invaders in, before springing the trap shut. With the revolution, Bolshevism as a creed demanded aggression, and being defensive was no longer enough, and with the rise of Communism, also came the rise of the leading figures who propounded the new theory of offensive operations, Frunze, Triandfilov and Tukhachevsky (quoting from memory, so the spellings might be horribly wrong).\n\nThese thinkers (mostly Triandfilov and Tukhachevsky) considered the following,\n\n(1) Can Russia stand upto another war of attrition? It had been successful in the past, but is it a guarantee of success in the future?\n(2) Space – Russian doctrine had always depended on trading space for time, and fighting defensively, but these thinkers challenged the dogma, and postulated that, the same space could also be used for an offensive strategy. As a digression, Zhukov used a reverse variant of Tukhachevsky’s offensive plan, as a 3 echeloned defensive plan (I am of the firm opinion that the Russian’s did not just stumble in the defense, and Father winter saved them, but that is a topic of an entirely different conversation)\n(3) Use strengths – Arty, masses of infantry have always been Russia’s strength and Sov doctrine married these strengths (which till then had been the hallmark of a static, defensive war) to the new doctrine of mobility as proposed by Fuller in the early 20th century, thereby resulting in what we now know as combined arms.\n(4) Weaknesses – Avoid pitched battles on Soviet soil, and take the battle to Western Europe and gain quick victories.\nThis theory \nhowever did not stretch as far as what the Germans did in terms of Radio net connectivity, use of air power etc etc, as Tukhachevsky was unfortunately purged before he could get there, and this entire theory died an unnatural death (until it was revived spectacularly in the counter offensive in Stalingrad)\n\n**What did this result in?**\n\nIt is too simplistic to say that Deep operations was only about battering a line in strength and then hope to break through to the enemies rear. The Sov army (especially post 42) started tailor making itself to this concept, and this is where the role of shock armies come in.\nDeep operations was also about maskirova (spelling?) and in ensuring that they enemy was completely on the backfoot on the chosen area of offensive. For instance during operation Uranus, Gehlen was entirely convinced that the offensive was going to be against Armee Group Centre- we talk about how FUSAG was formed in the UK, prior to D-Day, but Sov Russia created 3 fake armies, built 50 fake bridges (not exactly sure about this number) and entirely fooled German intel into where the strike was coming. This was the case during the Kursk counteroffensive and Operation Bagration as well (other examples of brilliantly executed Deep operations strikes).\nDeep operations was layered as below,\n(A) Shock army – massed infantry, heavy on sapper support backed by a overwhelming arty, mortars, Katyusha’s etc etc. You also had Shftrabats(spelling? Punishment battalions) clearing a path through minefields, but these were a very small component of the force deployed on an offensive. \n(B) Elite Guards Infantry units or regular infantry divisions as well\n(C) Armour\n(D) Cavalry Mechanised Groups\n\n**A** made the strike, these were divisions that were designed to take massive losses ,and their only role was in breaking through German lines – they had minimal mobility, communications capabilities or any of the other requirements for modern warfare. These units where the equivalent of the sledgehammer. \n\n **B** followed through, to deal with the second echelon German troops – this was an evolution in Sov tactics, and evolved as a response to Germany tactics of pulling back to a secondary line to ensure that the Arty impact was minimized (Gotthard Heinricci for instance was a genius at this tactic). \n**C** then completed the rout, and made deep penetrations, by then \n**D** (or also called Operational Exploitation Groups) were introduced into the gap, these were the units who roamed far to the rear of German lines and ravaged the Rollbahn (Armour also did the same, but lack of fuel stopped them long before the cavalry units were stopped).\n\nThe German “Blitzkrieg” also had a similar parent in Fuller’s ideas (some authors even say Guderian was deeply influenced by Tukhachevsky’s ideas – but apart from a couple of lines in Guderian’s memoirs, I have not been able to find a source to this claim), but the nature of this beast was entirely different. The Blitzkrieg considered the following,\n\n(1) Avoid the brutal war of attrition as seen in WW1\n(2) Avoid Static trench warfare, which favoured the combined (and stronger) economies of the allies\n(3) Essential to knockout the allies in the West before turning to the East to avoid a two front war\n(4) Manpower constraints, and use of force multipliers (Heinkel Tactical Bombers, Stuka’s, Panzer divisions) to even the manpower gap,\n(5) Shift in focus from a war with geographical objectives, to one that destroyed the maximum of enemy forces in minimum time.\nThis resulted in what we now know, and see as the extremely successful Blitzkrieg.\n\nIn this, as the German’s did not have the manpower to assault a wide section of the front, the entire force of the thrust was on the Schwerpunkt (again, spelling?) – or quite literally, the point of effort. It was NOT about recon by fire (probing for weakness in enemy lines, and then attacking the weakest point), but again intel played a big role in identifying (before the assault) the joints in opposing Armies, Corps (something like what Napoleon used to use), identifying clearly the lines of axis, and most importantly, about encirclements! The encirclements were planned affairs and the junctions of the pincers pre-defined.\n\nThe fundamental difference was that, Sov planning envisaged the substantial manpower reserves that were always available to it historically, and planned accordingly. Hence, the aim was more…”conventional” in that it did not seek a complete destruction of a large portion of the enemies OOB, whereas German planning was all about successive Cannae’s. \n\nInstead of Arty, the Germans leveraged their way superior CnC capabilities and used arty spotters embedded into each division, along with air spotting by spotters in Fieseler Storches, and used the Stuka’s as a moving arty. The initial attack was itself made by Armour and not by infantry, and the infantry was used to mop up the kessel’s while the armour moved onto the next encirclement / target. The logic in play here was to use all armour at the Schewrpunkt and brute force through the opposition lines, while the Luftwaffe on interdiction missions played havoc in enemy rear. Using infantry might have tangled the lines of communication, and clogged up the roads, and also giving the enemy time to react was the thought process here. It is important to note here though, Deep battle might have not been the success it became without the help of the humble Willy’s Jeeps and Studebacker trucks which immensely helped multiply Sov mobility.\n\nBoth Deep battle, and Blitzkrieg were products of the same thought – mobility over static warfare, and about bringing the war to a quick close, but the execution was as different as chalk is to cheese. In cases where deep operations failed (as in the example of the counter offensive at Moscow), it was entirely because of Stalin’s impatience and over ambition.\nThere seems to be a confusion on Deep operations, and that it involved attacks on multiple axis’, the thing is, those other offensive’s were a part of the maskirova, and meant to keep the German’s from switching reserves, the main scherpunkt (for lack of a better Sov word) was always pre-decided, and studied to the death. Take Op Uranus for instance, the planning for a counter offensive began towards the end of September, the site of the breakthrough was personally surveyed by both Zhukov and Vassilevski (spelling?), and completely pre-decided. The offensives by Chuikov, were more of a distraction to “fix” German troops.\n" ] }

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{ "a_id": [ "c62rbrz", "c62rgai", "c62rhfe", "c62sdmh", "c62tfs3", "c62txeb", "c62w6m9", "c62wxkg", "c62xwfi", "c6331os", "c634izq" ], "score": [ 17, 14, 82, 20, 29, 8, 13, 7, 8, 9, 9 ], "text": [ "Looks good, kudos to you and the mod team for being awesome and keeping r/AskHistorians a great place to learn about history.", "The rules on \"top level\" comments make sense when the post is an actual question, but not for the other types of permitted posts. How can a comment on a special occasion, meta or project post \"only be a answer to the question at hand\"?\n\nI suggest that you make it clear that this rule only applies to question posts.", " > [W]hile this is a public forum it is not an egalitarian one; not all answers will be treated as having equal merit.\n\nThank you for taking a clear stance on this issue and not pussy-footing around it. I come to this subreddit for content and there really is a very impressive panel of historians to provide that.\n\nAs a history buff, I always get the itch to pitch in my own two cents, but refrain from doing so as there probably is someone who can provide much more accurate information. (I should clarify that I am not implying that I have never found a helpful and on topic response from a non-flaired poster. Just that posts with people speculating and postulating have been on the rise..)\n\nTo the Mods and the panel, thanks a lot for all the work that you put into this subreddit!", "Thank you for the tier system. Its such a breathe of fresh air compared to askscience where everything is so clinical.", "top tier comments should allow for questions directed at OP (e.g. clarification requests).", "Awesome rules. I'm sure they will keep the high quality of this subreddit.", "I strongly prefer not allowing meta posts except from moderators. Subreddits around this size frequently decay to being nearly 50% meta and \"idea\" posts; \"let's talk about downvotes\" (or \"/r/askhistorians: we need to talk\") in particular will happen at least once a week. Just like everyone doesn't have the same subject authority, everyone doesn't have the same moderation or reform authority", "It all seems to be for the better. And I'm glad it's not going to be as strict about non top-tier jokes and speculation as /r/askscience.", "Thank you for continuing to keep /r/askhistorians one of the best-moderated subreddits out there. ", "After the Holocaust denial thread, I just wanted to say thanks, mods.", "These mostly have been the un-official rules for a while that were enforced by moderator and community consensus, we are just writing them down now." ] }

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[ "http://www.reddit.com/r/AskHistorians/comments/y94fc/special_occasion_post_243rd_birthday_of_napoleon/", "http://i.imgur.com/vZveY.png", "http://www.reddit.com/r/AskHistorians/comments/x9c4e/meta_new_projects_incoming/" ]

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{ "a_id": [ "f3zbfql" ], "score": [ 4 ], "text": [ "Phototherapy is noted to help people with seasonal depression. It involves basically shining a special lamp in your indoor space to help mitigate the lack of light that comes with autumn & winter." ] }

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{ "a_id": [ "cxgg10p" ], "score": [ 3 ], "text": [ "Actually, the crisper is the worst place to keep vegetables. They do better with air circulation and the temps higher in the fridge. The best thing to keep in the crisper are raw meats, primarily to prevent raw meat juices from dripping and contaminating anything else. The drawers are relatively easy to remove and sanitize afterward." ] }

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{ "a_id": [ "cpximvd" ], "score": [ 3 ], "text": [ "There's nothing distinctively different between a planet's orbit around a star and a moon's orbit around a planet--there simply needs to be sufficient distance between them where \"far enough\" depends on the object's sizes.\n\nEven asteroids [can have moons.](_URL_0_)\n\nEssentially the question you need to ask is this, can the system I want to make well approximated by a two-body system, can I ignore the parent orbit? For an Earth-Moon-Sun system, the answer is yes, we can ignore the Sun, the system is stable. If we cannot, and we *have to* describe things as a 3-body system, then we risk always ejecting one of the bodies over long times as a three body system is able to easily transfer momentum around, eventually it'll wander into the phase space that unbinds one of the objects.\n\nSo to answer your question, yes. This is why we're able to have satellites around Earth as well as satellites around the Moon. One more bit of nuance, it seems like \"cheating\" to ignore the third body, in principle, it can contribute to momentum transfer albeit tiny ones. Luckily for us, there is plenty of situations where the \"effective stability time\" blows up to values magnitudes older than our universe, the Earth-Sun-Moon system is one such example." ] }

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[ [ "http://en.wikipedia.org/wiki/243_Ida" ] ]

{ "a_id": [ "c25aekk" ], "score": [ 6 ], "text": [ "First: Its important to note that Brita and similar water pitchers are not just an activated carbon pitcher. There is also an ion exchange resin present in the filter. Think of this ion exchange resin as working just like a water softener (that is, because it does work exactly like a water softener).\n\nActivated carbon is really good at removing organic materials. Its safe to say that the vast majority of organics, you don't really want in your water anyway. \n\nThe other reason to use home-filtered water is if your water is hard -- which is where the ion exchange resin comes in. This is the part of the filter that removes any minerals. The way these resins work is that they are polymers which have counter-ions attached to them. Millions and gazillions of counter ions. The polymer is set up to have a negative charge and the counter ions are set up to be positive, typically sodium (which is why your home water softener takes salt -- ie NaCl, sodium chloride). There are more advanced water softeners and filters that will also exchange anions (negatively charged ions in water).\n\nWhat happens is that as the hard water flows through the pitcher, it interacts with the polymer. The polymer is designed so that it will bind to the minerals common in hard water (calcium, magnesium etc) better than it will to sodium. So it snags the \"hard\" tasting ions and replaces them with sodium. Eventually the filter is depleted of sodium and so the water starts to taste funny again because the resin isn't doing a good job of removing the calcium and magnesium. Home water softeners remedy this by running a highly concentrated salt water solution over the resin to force the calcium and magnesium out and replace the sodium content.\n\nFluoride, however, is a negatively charged ion and is not affected by the resins commonly available for home use. This is good, because fluoride is good for your teeth.\n\nOther 'trace' minerals that you need -- hard water doesn't contain nearly enough calcium to meet dietary needs. A lot of the other even tracer metals are poorly acquired through water. Here I'm talking about some of the ones that most people don't even think about but that [bullshit pseudo-science](_URL_0_) companies are happy to sell you at a high mark up. \n\nTo wrap up, any biologist who knows better is welcome to correct me on this, but basically: No, there are no health benefits or hurts. " ] }

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[ [ "http://www.harmonyminerals.com/" ] ]

{ "a_id": [ "clwy5lv", "clwy95d", "clwzhjp" ], "score": [ 8, 2, 2 ], "text": [ "The CVV is separate from the card number, so if people record your card number (such as a card skimmer), they don't have access to the 3 digit security code.\n\nIf you made it 19 digit, then 1 swipe and they have all they need to literally take all your cash.", "It helps cut down on the fradulent use of credit cards by hackers.\n \nThe security code is often not kept or used in face-to-face transactions (i.e. buying something with your credit card at the supermarket.)\nIf the supermarket's records were hacked, the hackers would not get your security code and therefore could not use it in card-not-present transactions (i.e. over the phone, online.)", "As a few peole have already pointed out, it keeps numbers in different places on the card (excep for AmEx) so a person can't take a quick look or picture and get all the info needed for many transactions, but I also wanted to add that (for Visa, MC, Amex, and Discover) it's not embossed into the card so if a store has to imprint it (we still do at my place of employment in certain situations) it's not imprinted along with the card number, name, and expiration date." ] }

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{ "a_id": [ "d1flpd1", "d1flsdi", "d1fno8p", "d1fo477" ], "score": [ 2, 16, 3, 2 ], "text": [ "Attacks in Western nations are discussed more in Western media. Attacks in nations that have been experiencing terrorism and war daily for decades, not so much.", "It's pretty much accepted that that part of the world is basically a warzone. Nobody's too surprised if something explodes or people die there.\n\nHowever if it happens in a modern major city, that IS a nasty shock. That kind of thing isn't \"supposed\" to happen in a \"civilised area\".\n\nRemember in the Dark Knight how the Joker talked about nobody panicking when things went \"according to plan\" even if the plan is horrifying? That's exactly it. You expect bombs to go off in a warzone, you don't expect them to go off in the middle of a major European city.", "Also I think that us Westerners have become very desensitised to anything bad that happens in the Middle East regions. Partly due to the way the media/hollywood have reported/portrayed the violence/wars etc from those regions for years, it goes hand in hand in most peoples minds so doesn't come as a shock to the system anymore. Also there is a growing them and us attitude, we feel more connected to fellow western nations.", "Speaking from a European perspective (sorry OP, I have no idea where you're from but I'm assuming from your username that it's the states) - Brussels and Paris are two things:\n\na) They're not considered warzones - Pakistan is both at war, and in the midde of an area from where we commonly hear of wars, so it doesn't register in a lot of people's heads as shocking. Brussels and Paris are considered peaceful, safe areas, so it's a much bigger shock.\n\nb) They're a lot closer to home. Pakistan? Syria? We can accept that bad events there are tragic and terrible, but we can dismiss them easily because they can be considered foreign places, with which your average person in my country has fairly limited interaction. It's why people can sometimes get so angry about, for example, Syrian refugees coming into the country, and feel no sympathy - the bad events happened far away in a country we don't know very much about, but the refugees are here in our front yard.\n\nAnd that's why we get scared about stuff like the Brussels attack, or the Paris attack, or the London bombings back in 2007 - these things are happening a matter of hours away from us.\n\nThat doesn't make them any more tragic, or the deaths any more deserving of being mourned than the deaths happening in the Middle-East, and I'm not trying to justify these views or reactions, but that's the way it is, and you're right, it's a form of Eurocentrism on our part. It's more surprising, more shocking and a lot scarier, and reminds us that we are involved in this conflict more than we would sometimes like to admit." ] }

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{ "a_id": [ "czynr8u", "czynuhg", "czyp3jf", "czypirb", "czypo5c", "czypybf", "czyqqzd", "czyqudm", "czyr03y", "czyr7kf", "czyt69w", "czytf5a", "czyuj1i", "czyv3ll", "czywig0", "czyzval", "czz7y4w", "czz8gtj", "czz8zw6", "czz9gzu", "czzeff2", "czzf1m9", "czzhv45" ], "score": [ 171, 4, 3, 3, 40, 7, 9, 2, 5, 2, 2, 3, 2, 2, 166, 3, 2, 2, 2, 2, 2, 2, 2 ], "text": [ "The latter, mostly. In the case of plants that use some sort of fuel, the energy is *already* stored in whatever fuel that is being used. Generating energy from the fuel first, and then storing it back inside something else to be extracted later is a *huge* waste of everything. When you have too much power, you use less fuel. When you have too little, you use more, it's generally as simple as that.\n\nIn case of solar plants and such however, it gets interesting. Storing large amounts of energy is one of the biggest problems of today's engineering and there is considerable research being done about this very issue. There are some ways of storing the energy that a solar plant generates during the day, but they aren't exactly ideal. It usually revolves around conversion of electricity into some other form of energy. Like using the power from a solar plant to pump very large amounts of water uphill, which is essentially converting electrical energy into potential energy. You later let the water flow downhill and turn some turbines to generate electricity again. Or you could use the power from your soalr plant to pump air inside a huge tank to create pressure, and when needed you let the highly pressurized air out and, again, turn turbines with it. Obviously there are considerable losses involved in such techniques, but energy storage technology is still a developing one. We're getting there.", "I just had a class on it yesterday! Just to be clear I'm just talking about non-renewable resources and electricity, I'm not sure if what I say here is also applicable to renewable resources plants.\n\n\nElectricity in big quantities (like in power plants) is not stored. It can only be produced. It is only stored in small quantities (batteries, for example) but so far people haven't created an efficient way to store big quantities of electricity. \n\n\n", "If you are referring to the large power plants (coal/lignite), they operate on supply/demand. There isn't really any noticeable storage of the energy and the electricity generated is immediately put onto the grid. \n\nIf there is excess supply than demand (ex. a nice day and no one needs heating/cooling) the energy may get sold to other adjacent grids operated by other companies that may need it. In the case of excess supply, the power plant will decrease production to reach and equilibrium.", "While everyone has explained a lot, I want ti add another interesting fact.\n\nElectricity is, in conventional generators, created by big turbines and generators. That means, if there's more energy consumed than produced, these turbines are slowed. When the reverse happens, they start to speed up.", "Just to add that there is a common way that large amounts of energy is stored for later use - [pumped storage hydroelectricity](_URL_0_).\n\nBasically when there's low demand for energy the excess energy is used to pump water from a reservoir into a 2nd reservoir that's higher up (eg. at the top of a hill). When energy demand increases they stop pumping and let the water flow down from the higher reservoir back into the lower reservoir, driving a generator as the water passes.", "So, my dad runs a series of hydroelectric dams on a river...his system is connected to a dam on a bay heading into Lake Michigan. There is a balance to maintain, too much can blow apart the system, too little causes brownouts. During heavy rain, the bay station will literally burn the river generated excess by pumping some lake water back into the bay! It's a wild system, one of his river dams is over 110 years old!!!! ", "Generally it's being used at capacity. Storage is one of the biggest problems with renewable energies. How do you take the solar power during the day, and cost effectively store it for use at night? Answer that question and you will be very rich.", "Several good answers here, batteries are costly and don't store much energy (on a large scale, and this is ELI5). Hydroelectric also works.\nFrom work experience, I'd like to offer this:\nI live in Texas, which basically has its own Electric Grid. I often drive to west Texas (think Midland/Odessa area), where they produce more electricity from wind than any other state in the US. If I take a slight detour, I will pass a wind generated power station that is not even connected to that grid, and charges all those oil/gas places on a rate that changes every 15 minutes. If the wind does die, diesel generators are brought online, and the cost of electricity can easily go from 8 cents per kWh, to over a dollar per kWh.", "there are many factors but the main one is current draw and voltage. these plants produce electricity in very high voltages (several hundred thousand volts on the main lines) and not so high current. the current we use in the household is via the drop down transformers (current and voltage are inversely proportional)and while voltage is relatively constant, current is drawn, not pushed, meaning if it isn't needed it's not there. what you perceive as a heavy load (say a 30 amp water heater) is nothing but milliamps to the grid. there is seldom an actual instant heavy spike on the demand of the generators supplying our grid and very easily accounted for. if there was actually no load draw on the generator it simply does not make the current, but does ensure the voltage is present.", "Yay, I actually know this. My father was head instrumentation specialists for a power plant. I worked at the plant during the summers while in college as well. I was fascinated by how it all worked and asked a lot of questions. \n\nThere is little to no storage of power. You have two types of power plants: baseload and load following. Baseload run at max capacity all of the time and load following shutdown when power isn't needed and start back up to handle peak power consumption during the day. You also have auxiliary power stations such as hydroelectric damns and what not. \n\nThe load is absorbed and controlled at each power plant and power station. The transformers can handle minor fluctuations, but the majority of the power output is controlled by the steam turbine of each power plant. The steam turbine for a coal plant usually turns at around 3000 rpms, but can speed up or slow down to adjust power output. A power grid usually has many power plants feeding the grid, and each plant is connected. Many plants have installed equipment that syncs each plant up so each plant knows what the other plant is doing to optimize level power output.\n\n30 years ago this was not always the case. My dad told me a story about how a long time ago some guy at one of the plants accidentally engaged a turbine before it was fully up to speed. Because it was not up to speed it actually started pulling power instead of delivering it. The instantaneous demand of massive amounts of power shock every power plant on the grid for hundreds of miles. My dad said it sounded like a giant bomb went off in every plant connected to the grid. \n\n ", "Having designed electric utility generation control systems, I can add on. There is no storage to meet short term demand changes (pumped hydro is another topic). The generating mass of the interconnected grid absorbs short term changes, showing up as a very small change in line frequency. A utility adjusts their output to meet demand as follows:\n\nA utility is connected to the grid through power lines, called tie lines. If the utility is not buying or selling power then the sum of the power flow through the tie lines should be zero. This sum is called the Area Control Error.\n\nIf the Area Control Error is negative, then generator output is increased, and if positive output is decreased, until the control error is zero.\n\nThere is a bias applied to the control error based on grid line frequency. If the line frequency is below target (60hz in North America), then the bias will cause over generation, and vice versa, with the intent that the grid frequency stays at target.\n\n", "Electric power grids work like enormous machines with many power plants feeding to a transmission system to provide needed power, like streams coming together in a river. American utilities are required to have a certain percentage of \"spining reserve\" which are power generators online to provide more than the current usage. Some power can be stored with hydroelectric dams and reserviors that can adapt to changes in load some even use pumps to return water during periods of low demand and high production. Other power plants can be turned on as needed to meet power requirements. Baseload plants are nuclear, coal and natural gas that produce steam and take a long time to bring up to speed and turn off. Faster response is with gas combustion turbines and reciprocating engines can have the fastest response to changing loads since they are like automobile engines that can be turned on and off easily and provide varying power as needed. Energy storage is one of the major goals in power engineering with all types of battery and other systems being developed and deployed to match the different power inputs with customer needs. \nSource: worked in utilities for 20 years and renewable energy for 35 years. Also living offgrid for 25 using solar, batteries and backup generators to supply all my power needs. ", "Generators have a certain capacity, usually expressed in MW, megawatts, which is a unit of *power*. Generation systems put a certain voltage, aka potential difference, onto the transmission systems and this voltage is a constant. The more load/draw on the system, the greater the current that flows through the conductors. Since power is a product of voltage*current the generator is capable of providing any amount of current up to a certain MW capacity. Beyond that capacity the generator would sustain heat damage, but protective systems would cut off some load in order to prevent this in a properly coordinated system. \n\nThat's how I understand it, and I am oversimplifying things by leaving out reactive and apparent power. ", "A few power plants actually have a pretty interesting strategy- they'll purposefully build the plant at the bottom of a mountain and by a large lake. When the plant's generating too much electricity it will use that power to pump a bunch of water from the lake to a dam at the top of the mountain. When energy demand is high, they'll open the dam, letting all of the water flow down the mountain and make hydroelectricity.", "Power Generation Engineer here, created username just to answer this because it's the only ELI5 I have ever been qualified to answer (have built and commissioned power plants all over the world for Westinghouse and Siemens for 20+ years).\n\nA thorough explanation is probably beyond ELI5 territory and I'm probably going to get hammered for this response length but screw it, it's a throwaway and I don't need the afirmation. There are plenty of correct pieces of answers in the comments. If you strung them together you wuld have a hell of a complete answer. In short, unless the electricity is produced and stored in grid connected battery banks or some other means DIRECTLY storing electricity without first converting into into another form then it is produced \"on demand\", as it's needed.\n\nHow well it is done is dependent on many factors but not limited too the type of power generation method employed, it's age, the intelegence of the plant control system or systems that operate it, the intelegence of the transmision systems that the electricity is transported on, and the level of connectivity that the individual power plants have with the grid operator (Independent System Operators in the USA) and to each other.\n\nIn the USA, we run the gammit in terms of technology and capabilities employed across all these areas but this has been the only reliable method of delivering bulk electricity to a mass consumer base for well over 100 years (thanks George Westinghouse and Nikola Tesla - you glorious bastards).\n\nAlso, the collective \"grid\" is capable of producing more than what is actualy needed at any given time. It's called spinning reserve. Let's say a coal plant in the SW USA is capable of producing 2000MWe. At any given time it might only be producing 800 to 1500 MWe. It's boilers are generating steam, it's steam turbines are spinning the generators and all systems are effectively on line. If the load on the electrical grid were to increase, it's generaly gradual in nature and rarely instantaneous. The power plant responds by increasing the fuel input to the boilers to increase steam production and thereby increase the power generated by the steam turbine. This coresponds to an increase in the power output at the generator terminals. This process happens relatively quickly even for an old coal plant and usualy faster than the coresponding load increase on th grid. This makes it possible for the power plant to match a load increase imposed by the electrical grid within miliseconds to seconds. In the case of the SW USA coal plant, it has an additional 800MW of capability that is available but not being utilized. The point is that yes, power plants will always follow a load change on the grid but the grid, for the most part, can tolerate the disturbance until the generators can catch up.\n\nA good analogue to this is a car driving across a flat plane that suddenly encounters a hill. In order to maintain speed going up the hill the driver has to press down on the accelerator to increase the power output from the engine in order to maintain speed. The driver presses the accelerator pedal IN RESPONSE to a decrease in speed caused by an increased load on the engine. The decreased speed, although noticeable, is quickly resolved becasue the driver (control system) and the car (generator) are capable of responding quickly, almost in real time.\n\nAs for grid frequency, this isn't only affected by load on the electrical system but the TYPE of load. The points made by others in the comments are all valid but I want to add that the frequency of the grid is important when discussing VARS which aside from voltage is the other major control variable that grid operators monitor.....but that's anothr ELI5.\n", "I work in this industry.\n\nGenerally, power is generated as it is needed. A control authority can give the power plants orders to increase or decrease output as needed. Some generators can be started and stopped very quickly, and provide what is called \"reserve power\". Others can change their output very easily and provide what is called \"regulation\". \n\nHowever, there is some storage, but it's a minority. Here in my home state, we have a power station in the mountains that is what is called a pumped storage station. They have a reservoir at the top of a hill and another at the bottom. When power is cheap, it gets stored by pumping water up to the upper reservoir. When they are asked to provide reserve power, they let the water flow down to the lower reservoir through some turbines, and they can bring a little over 1 GW of power to the grid in just 90 seconds . . . just shy of the amount needed to run a time machine.\n", "Mostly power is generated as it's needed. I work at a balancing authority that basically tells any given power plant \"Hey, we need this much power at this time\" and they'll produce what the market demands.", "Utilities have several tools to match generation to load and (new battery tech notwithstanding) energy is not stored on any large scale. Spinning reserve, VAR support, and quick turn up generation (combustion turbines and pumped storage) are used to handle the transitions in load. The plant operators and transmission dispatchers use voltage and frequency as indicators to determine which tool to use. \n\nWhen load is greater than generation the system voltage will decrease and the frequency will decline. Conversely, if the generation is in excess to the load the system voltage and frequency will increase.\n\nThe operators will run their generators at 80% (for example) anticipating going up to 100% to meet the peaks in demand. This way when the load goes up the demand can be met at the generating site (adding more excitation to the generator). As the load goes down the operators will reduce their excitation voltage to maintain the system voltage at an ideal level. Some utilities forecast this data to determine which generators will run at which levels based on fuel costs and maintenance schedules.\n\nVAR support works two ways, mainly through capacitors and reactors. Closing in the capacitors on the transmission system delivers VAR support closer to the load which raises the voltage further away from generation and allows the generator to run closer to unity which is a big scary math word for 'more efficiently'. Conversely, if the voltage gets too high (ie too much generation given the load) the power plants can lower the system voltage by opening capacitors and closing in reactors. Reactors simulate load which can be useful when dialing down the system voltage and loosely speaking can be thought of an opposite to capacitors for the purpose of voltage control.\n\nQuick turn up generation (pumped storage and gas combustion turbines, for example) are also useful in matching generation to load. It takes weeks or days to turn up nuclear or coal whereas these can be turned up in hours. Raccoon Mountain near Chattanooga, Tennessee is an example pumped storage but even in this case nothing is stored but the fuel. It is actually a net energy loss every time they fill the lake, but it is a financial success given the swing in energy costs throughout the day. Pump at midnight and release at 5pm for maximum return.\n\nDC systems (solar, wind) have made strides in pushing large battery banks into the limelight, but to the best of my knowledge the battery tech hasn't advanced enough to make this a reasonable financial option on any meaningful scale.", "The situation is soon to change from 2 to 1. Home and grid based energy storage will reduce pollution and enable residential power generation.\n\nHave a look through _URL_0_\n\nand the information on this company's page will supplement on near future changes in power grids:\n\n_URL_1_", "Made as needed.\n\nBasically it's like your car, you start going up a hill, you put your foot down harder to stay at the same speed and lift off as you go over the hill.\n\nInstead of a hill, it's how much power people are using. They just control \"the throttle\" at the power station much like you do in a car to keep it going the same speed.\n\nThat should be a nice eli5 version", "Currently it's mostly generated as needed. There are base load plants that create energy at a constant rate and then there are peaker plants that ballance the load during peak time. Peaker power plants are by and large run on natural gas and can be powered on and off relatively quickly when compared to nuclear or coal power plants. \n\nEnergy storage has been used for peak time load balancing for some time but it's not widely used. The most common method used so far has been pumped hydro, but it's not cost effective or technically possible everywhere. Lately there has been a huge incentive to expand utility scale energy storage, primaraly due to renewable energy which is intermittent. Peak load ballancing using stored energy could replace peaker plants and possibly even coal and nuclear plants if enough renewable sources are used.\n\nFor home use batteries are also making more financial sense, not just to store electricity from PV panels but also to have a backup in case of power failure or for storing cheap electricity for later use when it's sold at a higher cost during peak consumption from the grid.", "Power isn't stored. A key principle of a power grid is that demand must match supply to balance the system. \n\nThe Power Grid operator can call on dormant units to generate or if there is a excess of supply, the grid can tell generating stations to reduce output or even shut down.\n\nTo fine tune the balance of the power grid (matching demand to Supply) larger power stations have a facility called Frequency Response. The Power Grid Operator uses Frequency Response (FR) to fine tune supply to match demand. A Power Station Operator of a unit providing FR might see his generation output shift up and down a couple of MWh to help balance the power grid.\n\nSource: I work in the UK energy industry ", "Electrical engineer here. Many good answers on here to summarize into a proper ELI5:\n\nSystem basics: Imagine a team of hundreds of horses drawing thousands of small carts all hooked together behind each other. If one horse dies or an extra cart is added it wont have much of an effect on the system as a whole. If all the horses stop at the same time the whole system will stop nearly instantly.\n\nRegulation: To regulate the system there is a conductor with a whip to make the horses put in some extra effort or slack off a bit. He also has some quick release systems to disconnect some of the carts or groups of carts or even some of the horses if they pull too hard. The conductor makes sure the system is always pulled at exactly the same speed (he has a very fancy speedo) and manages connections/disconnections.\n\nLoad prediction: After a few years of this the conductor can start predicting when people will be hooking on their carts or taking them off and so can plan when to add more horses to his team or take some off to rest them.\n\nEnergy storage: At times there are too little horses to pull all the carts. For this they have bred a special wind-up horse. This horse is actually a drag on the other horses but winds itself up while its dragging the others down. But its okay because it can also help pull when there are too little horses. So the conductor can tell it to either help push when there are too little horses or drag the other horses when there are too many horses. This way he conductor can utilize the real horses to their max all the time instead of letting them to pasture and still having to pay for their upkeep." ] }

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[ [], [], [], [], [ "https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricity" ], [], [], [], [], [], [], [], [], [], [], [], [], [], [ "https://www.reddit.com/r/energystorage", "redflow.com" ], [], [], [], [] ]

{ "a_id": [ "c1gu0gg", "c1gu4d1", "c1guxep" ], "score": [ 3, 3, 3 ], "text": [ "You might be describing something a bit like [genetic programming.](_URL_0_) I believe these still require someone to determine the fitness of each program, but if you have some desired output and a set input, you can have something compare what the program produces to what you want the output to be and the algorithm will fix itself, maybe. Disclaimer, I'm just a student and don't know a ton about computer science just yet! So that could all be wrong. First thing that popped into my head though on reading this post.\n\n[Here's a program](_URL_1_) that can write music based on previous works and a human teacher for its output.\n\nHah, and [here's the album](_URL_2_) it wrote. Ridiculous.", "Genetic programming works well on a certain subset of problems; such problems tend to revolve around somewhat esoteric things like finding optimal algorithms (i.e. don't try to evolve a genetic program to add new features to facebook, but maybe you could use one to search for a way for facebook to optimize the way they store their node graph internally). In addition, the solution space for the problems need to have \"smoothness\"; in other words, they work best for problems where if a solution A is somewhat good, then solution B which lies \"nearby\" A has a strong chance of being good or better. So, it has \"taken off\" to an extent in the limited space of problems it's well suited for.\n\nAlso, genetic programs tend to come out rather...interesting. The actual code they produce tends to look bizarre, and it can be very difficult for a human engineer to intuit how they work, even when they still give the right answers. When humans write code, they are also reading the code they write, but the genetic algorithm doesn't care about making the code readable or understandable, so you end up with some pretty crazy stuff. I read an article once (way too long ago to remember details) about an optimal program which was generated, and when the researches reverse engineered it to discover how it worked they found it actually took advantage of a bug in the hardware they were running the simulation on, and if the bug was fixed the optimal solution no longer gave correct answers. In a similar fashion, they are very sensitive to the fitness function used to rank the candidate programs. It's common to evolve programs that work very well when ranked according to a certain specification of the problem, but change the target even slightly in a way that human-written code could easily adapt to, and they fall apart.", "I'm currently doing a Master's in AI, actually. My goal for the degree is to acquire the theoretical background I need to realize my longer-term goal: building a robust general problem solving agent. The tool will be able to construct simple scripts that meet a set of \"almost-natural-language\" criteria. \n\nGenetic programming is a nice approach, but dead-ends in the type of domains I find interesting. My approach is rooted in logic programming, so it is essentially constructivist, but the ultimate idea is for the system to learn the logic domains automatically by using data mining approaches.\n\nCombining data mining and advanced logic programming in a feedback loop modeled on real cognitive processes should allow for a relatively flexible system, capable of fairly complex tasks in acceptably realistic (noisy) environments." ] }

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[ "http://en.wikipedia.org/wiki/Genetic_programming" ]

[ [ "http://en.wikipedia.org/wiki/Genetic_programming", "http://en.wikipedia.org/wiki/Emily_Howell", "http://www.amazon.com/Emily-Howell-From-Darkness-Light/dp/B004FC8RD6" ], [], [] ]

{ "a_id": [ "d9d3n6x" ], "score": [ 2 ], "text": [ "Unfortunately I don't think this an answerable question. \"Arab blood\" does not define Arabness. Arabness is at least partially a linguistically defined ethnicity. That's why dark-skinned dark-eyed [Anwar Sadat](_URL_2_) is just as much an Arab as light-skinned blue-eyed [Bashar al-Assad](_URL_0_) is an Arab.\n\nAside from that definitional issue, our earliest sources, including biblical references, are to \"Saracens\", not Arabs. It's not at all clear who is being referred to when these classical sources are referring to Saracens. For instance while some sources might be using it in the sense that we mean of \"ethnicity\", and therefore define the area of territory occupied by Saracens broadly, others are using an unusually narrow definition, where, for instance, Saracens are the people who live in one very specific place. [This can easily be misrepresented by Arab nationalists](_URL_1_) in cumulative fashion as suggesting that some huge portion of the Middle East was meaningfully \"Arab\" from a very early period. Maybe. I'm hugely, hugely skeptical.\n\nMost of the writers we're relying on for these descriptions in the classical era have never been to the Middle East, have no idea who lives there, and the picture will remain fuzzy until the Arab conquests themselves.\n\nI think the best we can probably do is to say that there were strong tribal connections throughout the region. Quite good linguistic connections. But making definitive statements in terms of percentages for ethnic populations is just not possible." ] }

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[ [ "http://www.eheraldpost.com/en/wp-content/uploads/2014/06/Bashar_al_Assad.jpg", "https://www.reddit.com/r/arabs/comments/3if0in/the_distribution_of_peoples_described_as_arabs_by/", "https://media1.britannica.com/eb-media/77/93077-004-9CEFFCB4.jpg" ] ]

{ "a_id": [ "cy3jcj5", "cy5alcx" ], "score": [ 3, 2 ], "text": [ "Water vapour condensed out of the air due to the sudden drop in pressure in the neck of the bottle would be my guess.", "When a gas expands it's temperature drops. When opening a beer bottle the CO2 in it rapidly expands and cools down causing water vapor in it to condense." ] }

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{ "a_id": [ "fgp5izc" ], "score": [ 14 ], "text": [ "Frankish hegemony over transrhenan peoples was less due to conquest or overpowering campaigns, and more to a policy of personal relationships, trade, raids and counter-raids that weren't that dissimilar to Rome's policies in Germania and that tended to define sort of a Frankish \"sphere of influence/power projection\" up to the Elbe, but also in Northern Italy, Armorica, southern England and Spain.\n\nWhile Clovis battled against Alamans and Thuringians already in the late Vth and early VIth centuries, it mostly concerned groups established or raiding Gaul, not campaigns going beyond the Rhine. These peoples entering into Ostrogothic protection under Theodoric, the establishment of a Frankish hegemony in Germania can be more easily associated with the reign of Theudeuric I, who ruled the Northern-Eastern part of the Frankish realm and directly at contact with its polities (or raiders, as evidenced by the failed Danish raid of 516, whom defeat made enough of an impression to be accounted for in Beowulf).\n\nThis hegemony can mostly be traced from the reigns of Clovis' sons, especially Theudeuric who ruled over the lands associated with Franks since the IVth century and that was in direct contact with Frisians, Saxons, Alamans and Thuringians. The last two peoples already clashed with Franks during Clovis' reign, but mostly groups that were present in Gaul, the rest benefiting from the powerful and prestigious protection of Theodoric, king of Ostrogoths, a protection that disappeared in the VIth century along the decline and fall of the Ostrogothic kingdom itself.\n\nAs Francia appeared as the most prosperous and powerful polity of post-imperial western Europe and as kings in Italy were unable to really preserve Theodoric's diplomatic network, Franks were a necessary and powerful partner : the first Frankish intervention in Thuringia (with Merovingian kings probably had genealogical relations with) was even made at the behalf of a Thuringian king against another, hoping to get half of it which they did after an obscure situation where the supported candidate died. It's not that they annexed all of Thuringia : a good part was eventually swallowed up by neighboring entities, Germanic or Slavic, and the land within the realm was probably let to local nobles (led by a duke at least in the VIIth century, hinting at an \"ethnic\" rulership even if he was Frankish), poorly settled at best by Franks, with local populations being held tributary. The Thuringian exemple, eventually, can be set for the lot of Germanic principalties under Frankish influence.\n\nRather than a conquest, what was important for Merovingians was their capacity to halt raids, raid beyond the Rhine themselves and obtain both loot and substential tribute, raising auxiliaries and enforce their claims of over-lordship by including them into a personal and genealogical relationship as duces (dukes) although they probably had royal titles (in a system not unlike the Chinese tributary system, local and regional kings in Germany, Wasconia or Brittany weren't considered as such by Franks, who called them counts or dukes). On this regard, the difference usually made between Alamans, Bavarians and Thuringians from one hand; Frisians and Saxons from another one might not be that radical (Saxons, for exemple, being extorted a tribute and considered as rebels when refusing to pay up).\n\nOf course, this was true when the Merovingian kings were able to enforce their rule beyond their borders, bullying their way into submission of local kings (especially under the reigns of Theudeuric I, Clothar I, Clothar II and Dagobert); but at the first sign of weakness, a revolt was always possible as it happened to Clothar I against Saxons (and as Marcomanni did with Marcus Aurelius in their time); even the own successes of peripheral rulers could led them to challenge Franks (such as Radulf, victorious against Wendish raiders and successfully beating Dagobert's Franks).\n\nThis could give the impression that Frankish Germania was kind of an aftertought, but it seems to have been rather the contrary : tributes payed in cattle, horses, possibly slaves were important, levied men served as auxiliaries in Frankish campaigns as soon as in Northern Italy and as late as the VIIIth century. It's just that, as Romans before, Merovingians were content (or had to do) with a fluctuating and warlord-ish relationship where their hegemony had to be regularly reasserted by demonstrations of strength or battle; rather than an effective conquest. That said, even this complex relationship left marks : local dynasties and nobilities were \"Frenchified\" to an extent, allowing Carolingians to maintain genealogic ties with dynasties such as Agilofings in Bavaria, giving some leeway to integrate them further to Francia (establishing law codes, notably, and \"preparing\" their annexation) and serving as model for further conquests such as in Frisia or Saxony : these conquest, as real they were, were also not so much \"efficient\" than brutal and requiring a lot of resources and attention from early Carolingian kings compared to the more light weighted management of Merovingians." ] }

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{ "a_id": [ "c1eolp8", "c1eom1g", "c1eomoa", "c1ep32y", "c1epgzs" ], "score": [ 8, 2, 13, 2, 3 ], "text": [ "['Laws of Science' on Wikipedia](_URL_0_)\n\nTheories are models. 'The world is like this'. Laws are fundamental rules that always apply (in the specified circumstances) and are distilled into statements of fact. Natural selection could perhaps be formulated into a law, or set of laws, but evolution is not a simple proposition.", "I don't think laws and theories are really the same thing. \n\nTheories are conceptual frameworks that suggests at a mechanistic explanation at how something happens, while laws seem to tend to be concise statement of a specific, accurate observation. \n\nFor instance, Newton's law of gravitation is just a specific equation relating the strength of a gravitational force to the masses and distance of the objects, while the theory of gravitation encompasses things like general relativity and how gravity works and what it affects.\n\nI could be wrong, but that's what I always interpreted laws as. In any case, there are hardly any laws in biology since few things are ever concise and simple and almost nothing is ever absolute. ", "There's nothing weak about the word theory. For instance, quantum field theory is the most accurate description of nature that we have.\n\nAs for laws and theorems in physics:\n\n*Bell's theorem\n\n*Newton's law of gravity, laws of motion, law of heating and cooling\n\n*Kirkchoff's laws\n\n*Kepler's laws\n\n*Laws of thermodynamics\n\nAre a few\n", "\"Laws\" tend to have an explicit mathematical definition, that is an equation describing the how some quantity varies with another (often time). It is unlikely that evolution could ever be a \"law\" as there is no one equation which can describe it: it is a large number of related and competing processes acting in tandem.\n\nAs an aside, personally I hate the term \"law\". \"Law\" implies something is absolute, and eternal, and true. Of course, this not the case at all. So-called laws are in fact just models of systems which seem to agree with experimental results/observations. E.g newton's laws are not correct: they work under certain conditions, but fail under others. Einstein improved on Newton with special relativity, and we now know that relativity offers a better and more complete description of motion. \n ", "There are no rules as to what constitutes a Law and what constitutes a Theory.\n\nThere is no smoke filled back room where scientists deliberate over whether it is to time to \"promote\" a Theory to a Law.\n\nThere are Conjectures and Hypotheses that are undisputed, and Laws that are completely wrong. \n\nThe only real \"rule\" is whatever label something had when it became widely know, that is the one that sticks. " ] }

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[ [ "http://en.wikipedia.org/wiki/Laws_of_science" ], [], [], [], [] ]

{ "a_id": [ "c9tqjvl" ], "score": [ 5 ], "text": [ "So that players who try to anticipate the drop and thus start their swing faster don't get an advantage. They are supposed to wait until the puck is dropped to start their swing. " ] }

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{ "a_id": [ "ctabjsp", "ctabmqd", "ctac6yq" ], "score": [ 13, 3, 2 ], "text": [ "This is an older design of common cans. Let this guy shed some light on it in the most interesting can-related video ever produced:\n\n_URL_0_", "These are regular soda cans from some years back. Factories in some locations have older equipment.", "There is a 'side bar' at the bottom of this [newspaper article](_URL_0_) that lines up with the memory I have from taking a tour of the factory as a kid. In a nutshell, the crimped cans take less aluminum to make. \n \nShipping to Hawaii is pretty expensive - other than airlines with people, I would surprised if the soda that comes in to the islands comes via air, I would expect it is put on a ship (about a 5-day trip). The rest of the cans are made by Ball. Ball has a plant in Kapolei Hawaii that makes the aluminum cans for most everyone in the state (soda, beer, sparkling water, etc.) I believe they are the single source for aluminum manufacturing for the state having purchased the factory from Reynolds in the late 1970s. \n " ] }

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[ "http://i.imgur.com/90prBWV.jpg" ]

[ [ "https://www.youtube.com/watch?v=hUhisi2FBuw" ], [], [ "http://archives.starbulletin.com/2008/04/20/business/story01.html" ] ]

{ "a_id": [ "dk9uxoa" ], "score": [ 6 ], "text": [ "Post this to r/latin--I think they'd get a kick out of it. :)" ] }

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{ "a_id": [ "cfmdd2x" ], "score": [ 6 ], "text": [ "This is bull they by definition did commi war crimes facts are not opinions" ] }

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{ "a_id": [ "crs3h2y", "crs3lu9" ], "score": [ 4, 3 ], "text": [ "If someone is offering \"room and board\", they are offering to house and feed you (generally). This sometimes is forgotten, but that's what it means.", "When lodging somewhere \"room\" refers to where you stay and \"board\" refers to the food. \n\nThe term comes from the word \"board\" being used as a word for table back in the day. Meals would be served on the \"board\" of an inn or house for the lodgers and it eventually became synonymous with served food." ] }

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{ "a_id": [ "com53iw" ], "score": [ 5 ], "text": [ "There are many ways that can happen - basically every method of lighting that isn't incandescent light is an example.\n\n[Light-emitting diode](_URL_5_) uses electricity to push electrons to a high energy state, and at the junction the electron falls to a lower state and emits a photon.\n\n[Fluorescent lamp](_URL_11_) also uses electricity, but in this case electrons are fired between the electrodes. They impact mercury vapour in the fluorescent lamp, which excites the electrons within, and when they relax they emit a photon. One further step involves this emitted photon exciting electrons in the coating, which when relaxed emits a photon in the visible range. The phenomenon of exciting an atom with incident light and emitting a photon that way is [fluorescence](_URL_9_).\n\nA similar phenomenon is [phosphorescence](_URL_0_), which also involves photoexcitation, but the relaxation occurs at a much longer timescale as the excited electron goes through [intersystem crossing](_URL_2_) before emitting a photon. You may have encountered this in many glow-in-the-dark toys or paint.\n\nSpeaking of glow-in-the-dark, back in the days, before the dangers of radioactivity was discovered, [radium](_URL_7_) was widely used in glow-in-the-dark paint. During radioactive decay, ionizing radiation is emitted, one of which are beta particles - energized electrons. The idea is the same as the above example of fluorescent lamp - you can harness the energy of those electrons by using a fluorescent coating. This is known as [radioluminescence](_URL_12_). Nowadays, [tritium](_URL_3_) is the safe radioluminescent source.\n\nYou also have [chemiluminescence](_URL_8_), where a chemical reaction produces a product with an excited electron, which then relaxes and emits a photon. This is the principle behind glowsticks, and also [luminol spray](_URL_6_) used to detect blood in crime scenes. When the chemical reaction is biological in nature (like in fireflies), we call this [bioluminescence](_URL_10_). In many biology labs an enzyme used in bioluminescence, [luciferase](_URL_1_), is used to track transcription.\n\nA relatively recent and not-yet-fully-understood discovery is [triboluminescence](_URL_4_), where mechanical stress on the material causes charge separation and emission. Some famous examples are the emission of x-rays when unrolling Scotch tape, and glowing of mint [Life Savers](_URL_13_) when crushed.\n\nSo there are quite a number of ways to excite electrons without using heat. Many of these are already widely used, in household lighting, monitor displays, etc." ] }

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[ [ "http://en.wikipedia.org/wiki/Phosphorescence", "http://en.wikipedia.org/wiki/Luciferase", "http://en.wikipedia.org/wiki/Intersystem_crossing", "http://en.wikipedia.org/wiki/Tritium_illumination", "http://en.wikipedia.org/wiki/Triboluminescence", "http://en.wikipedia.org/wiki/Light-emitting_diode", "http://en.wikipedia.org/wiki/Luminol", "http://en.wikipedia.org/wiki/Radium", "http://en.wikipedia.org/wiki/Chemiluminescence", "http://en.wikipedia.org/wiki/Fluorescence", "http://en.wikipedia.org/wiki/Bioluminescence", "http://en.wikipedia.org/wiki/Fluorescent_lamp", "http://en.wikipedia.org/wiki/Radioluminescence", "http://en.wikipedia.org/wiki/Life_Savers" ] ]

{ "a_id": [ "d7bzlzk" ], "score": [ 20 ], "text": [ " > Yet both Union and Confederate cavalry corps operated almost exclusively as dragoons. Why was this? To what extent was this affected by the duties of pre-war US cavalry, and/or the lack of a European-style military establishment? \n\nThe ways in which Union and Confederate cavalry came to operate during the war depended a lot on the availability and quality of mounts, the terrain on which the fighting took place, and the quality of training. The quality of Union remounts was appalling at the start of the war, with unbroken horses and those too young or old to ride effectively among other issues, being purchased en masse and poorly taken care of. Until George Stoneman took over as Chief of US Cavalry in 1863, and Sheridan as head of the Union Cavalry Corps, the situation didn't really improve. By the estimates of one French military attachee, Union Regiments went through up to 6 horses per annum per trooper, in the first 3 years of the war. The Confederates were somewhat better mounted initially, the horses often being personal mounts from home, these were irreplaceable and scarce by the later part of the war, 1864-65. So on both sides, poor quality mounts constrained the chances for mass adoption of shock tactics when these were appropriate. Shock action also required a good deal of training, as well as skillful execution to ensure success. Stephen G. Starr indicates that units that enjoyed initial success with the saber were more likely to continue with using it than those who were met with failure. For example, The 17th Mounted Infantry charged Bedford-Forrest's dismounted troopers at Bolger's Creek on April 1st, 1865, despite being raised and designated \"mounted infantry.\" Most units appeared to favour firearms simply due to the ease of training and their being easier to obtain. \n\nThe lack of quality mounts, and the difficulty in training men for shock action compared to dismounted fire action, were further compounded by the terrain in which much of the war was fought. Stephen Badsey lays out the problem quite well:\n\n > The main theatre of war, in Virginia, was by European standards \nheavy ground, hilly, sparsely populated, with large virgin forests. This was scarcely ideal for the charge. The Western Theatre, far larger, saw considerable variation in terrain, but even there, so Colonel Duke of the Confederate Cavalry wrote: \"The nature of the ground on which we generally fought, covered with dense woods or crossed with high fences, and the impossibility of devoting sufficient time to the training of the horses, rendered the employment of large bodies of mounted men to any good purpose very difficult.\"\n\nMassed cavalry charges of divisions or more were very rare (it should be noted that this was historically the case even in Europe), but actions in troop, squadron and regiment strength were possible. A charge didn't even necessarily need to involve edged weapons; troopers with revolvers, carbines or rifles could \"gallop\" a position, charging up to it and dismounting to open fire. Shock action and dismounted action could also be combined quite effectively, as in the case of J.H. Morgan's charge at Shiloh in 1862, and in the clash between Pleasonton and Stuarts Cavalry in 1863.\n\nTo conclude, it might be more proper to say that American Cavalry, Union and Confederate, functioned more as 'Mounted Rifles' or 'Hybrid Cavalry', as 19th and early 20th century British (and Dominion) military writers termed them. In the former case, fire action dismounted was prioritized, but shock action could be resorted to in special circumstances, while Cavalry's scouting role was still central. In the latter case, emphasis was placed on shock action, but combining artillery and machine guns, as well as dismounted firepower. They weren't necessarily Dragoons who simply used their horses for transport, but could display great versatility in their tactics and missions. \n\nSources:\n\n* \"The Obsolescence of the Arme Blanche and Technological Determinism in British Military History\" and \"Writing Horses into American Civil War History\" by Gervase Phillips\n* [Fire and the Sword: The British Army and the Arme Blanche \nControversy 1871-1921] (_URL_1_) by Stephen Badsey\n* \"Cold Steel: The Saber and the Union Cavalry,\" by Stephen G. Starr\n\nThis [essay] (_URL_2_) on Civil War Cavalry from before WWI is worth a read, as is Alonzo Gray's [Cavalry Tactics as illustrated by the War of the Rebellion] (_URL_0_)" ] }

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[ [ "https://archive.org/details/cavalrytacticsa00graygoog", "https://www.repository.cam.ac.uk/bitstream/handle/1810/244878/Badsey12201.pdf?sequence=1&amp;isAllowed=y", "http://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A2001.05.0109" ] ]

{ "a_id": [ "cuzzkhn", "cuzznlv", "cv001lf", "cv05rin" ], "score": [ 4, 45, 7, 11 ], "text": [ "My assumption is that it has to do with the relatively rigid and formal social norms and politeness of Japanese culture in every day social interactions and also their cultural ideas of ideal man and woman. As a consequence certain behavior not tolerated at all in normal everyday life, like really uninhibited sexuality, breaking down the rigid norms and such can form as sexual role play fantasies which are then played out in porn in an exaggerated form.", "I would theorize it comes partially from the cultural status of women in japan as submissive beings that you can force your will on, and partially from the value of purity in the sense that a women *wanting* it is slutty. As a result you get a power fantasy of forceful men and an unwanting/pure woman.\n\nAt least in hentai there is also a difference between \"true\" rape and corruption rape, the former has the girl remaining resistant until the end, and seems to me to remain somewhat rare - The corruption of purity on the other hand seems to be *extremely* popular, in which case the girl is reluctant *at first* and then \"learns to love it\". So basically, turning someone pure and innocent to corrupt and slutty is what's fetishized here more so than the actual rape.", "Japan has very unusual censorship laws, essentially banning the direct display of sex/genitals that most porn relies on. So Japanese porn has to use other factors to attract/keep viewers. \n\nI'm not sure how the laws affect animation, but I know they are a factor in the rise of 'bukkake' and Japanese (live action) porn's unusual subject matter and style.\n\nAlso, as others have mentioned, Japanese culture has traditionally had a big emphasis on submission, and deference to those in power (especially by women). They also have a very long history of erotic art (ukiyo-e IIRC). No doubt this is also a major factor.", "The Western christianist mindset is guilt-based, which is an internal self-judging process-- am I a bad person for watching this naughty cartoon rape scene? Yes, yes I am, and now I feel bad about what a despicable POS I am. No one could or should ever love me. Jesus, forgive me my sinful thoughts! You do? Praise the Lord and pass the butter, now I can get on with my life again.\n\nJapan is shame-based-- go ahead and indulge your freaky hentai urges privately but once you set foot out the front door your responsibility for the next 12 hours is to conduct yourself according to society's rigidly prescribed behaviors. It's restrictive and repressive, but the other 12 hours of the day are all yours to freely express whatever variety of funkiness you happen to be into. Just keep it to yourself and some like-minded others, and possibly a trusted friend or two.\n\nTwo approaches to the pressure-relief valve necessary for the human individual coping with life in a complex society." ] }

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{ "a_id": [ "d01huip", "d01l9or", "d01rsnx", "d01wvfj" ], "score": [ 2, 17, 2, 3 ], "text": [ "The mechanism that controls VZV latency is not well understood. There are several factors that may increase risk with regard to recurrent shingle episodes. Aging, immunosuppression, intrauterine\nexposure to VZV, and having had varicella at a young\nage are all thought to play a role in the recurrent infection.", "My professor explained it as a cellular vs humoral immunity question.\n\nAntibodies do a great job of stopping spread in humors (blood, interstitial fluid, etc.) -- hence antibody immunity is called humoral immunity. But, Varicella Zoster Virus (VZV) survives in the nerve (dorsal root ganglia, to be specific), which is an immune-privileged site -- no antibodies or T cells are getting into a nerve. So when the virus decides to come out of the nerve back to the skin cells (not well understood when or why, as CD8plus said), it can easily track along the nerve and infect adjacent cells.\n\n & nbsp;\n\nSo, our only way of getting rid of the VZV outbreak in our skin cells (ie shingles) is for T cells to move in and purge the infected cells. This takes a while, and is very inflammatory.", "There are good answers here already. One important point is that VZV is a member of the herpesvirus family, and as a group these are tremendous sophisticated and complex viruses. They have very large genomes (for viruses, that is), and many of their genes target the host immune system and manipulate host cells in various ways. They're ancient -- their evolutionary history can readily be traced back hundreds of millions of years -- and extremely well adapted to their host species. Many herpesviruses have different, but equally subtle and powerful ways of avoiding immunity, so that they're capable of setting up life-long infections with intermittent new outbreaks.", "I have a bit of a follow up question, since I've seen some commercials with Terry Bradshaw advertising a vaccine for singles how does that work? Is it separate from the chicken pox vaccine? Can someone who had chicken pox still get the shingles vaccine (and expect the efficacy to be reasonable)? " ] }

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{ "a_id": [ "dar66zl" ], "score": [ 3 ], "text": [ " > The surface pressure on Mars is equivalent to the range of pressures on Earth at altitudes between ~30 km and ~60 km. \n\n--[Math Encounters Blog](_URL_1_)\n\n > At altitudes above 50,000 feet [_15.2 km_] man requires a pressurized suit to be safe in this near space environment. \n\n--[A Brief History of the Pressure Suit](_URL_0_)\n\n > At 55,000 feet [_16.76 km_], atmospheric pressure is so low that water vapor in the body appears to boil causing the skin to inflate like a balloon. At 63,000 feet [_19.2 km_] blood at normal body temperature (98 F) appears to boil. ... At altitudes above 65,000 feet [_19.8 km_] atmospheric pressure approaches that of space, that is the pressurization factors for protective equipment to be used at 65,000 feet are essentially the same as would be required for survival in a vacuum.\n\n--[A Brief History of the Pressure Suit](_URL_0_)" ] }

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[ [ "https://www.nasa.gov/centers/dryden/research/AirSci/ER-2/pshis.html", "http://mathscinotes.com/2012/10/earth-altitude-with-equivalent-pressure-to-mars/" ] ]

{ "a_id": [ "dffx72q", "dffzeyq", "dfg4ehn" ], "score": [ 5, 88, 5 ], "text": [ "It generally covers the human perception of reality, that we are limited by our senses and our brains, and aren't really capable of perceiving or conceiving the 'true' nature of the universe. Human perception and instinct being flawed, he suggested that moral and aesthetic questions should be answered through reasoned thought over emotional reaction.", "Kant answers 3 big questions:\n\n\n1- what is reality? \n\n\nKant says there's a real world outside of your body. But the way you experience this world (using your senses of seeing, hearing, touching etc.) creates a map, or model, of this outside reality in your mind, which is unique to YOU. Even things like space and time are unique to you. So if you had different senses, like Superman has superhearing, you'd have a completely different model of reality.\n\n\n2- what should be? (Right and wrong)\n\n\nThis is Kant's most famous contribution (categorical imperatives.) It means when you conclude that something is wrong, it is wrong 100% of the time, under any circumstances, and for everybody. You can't say murder is wrong then justify using it in some situations (capital punishment, war, etc.) It does not change nor does it matter where or when. \n\n\nHis point is that because your model of reality is unique to you, you can always come up with situations to convince yourself what you're doing isn't wrong (\"it's not stealing if you're starving.\") And there would be no sense of morality if enough people do that. The only way that there can be any morality is that right and wrong are universally established.\n\n\n3- How should society be governed?\n\n\nSo since right and wrong are universal, societies should be governed by a constitution and by the rule of law. Pure democracy (rule of majority) is not the answer, because no matter how many people believe something to be right, wrong is always wrong.", "1: u/sexypundit's comment is pretty accurate, and I'd like to attend you of the reply I made to it.\n\n2: Stay off wikipedia when it comes to philosophy, and read the Stanford Encyclopaedia of Philosophy instead. Much better, because it is written and edited by academics in the respective field." ] }

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{ "a_id": [ "c36azar", "c36b5v1", "c36azar", "c36b5v1" ], "score": [ 3, 3, 3, 3 ], "text": [ "Unstable nuclei will eventually decay and emit radiation. If something is bombarded with neutrons, some of them are captured by the nuclei, which can become unstable. In the case of water, it's possible that some could be captured to produce tritium, which is radioactive.", "Radioactivity is really a property of the nucleus of an atom. Unstable nuclei will decay and throw off pieces of itself (alpha, or neutron radiation) and electrons (beta radiation) and photons (x-ray or gamma ray radiation).\n\nThere are two ways water can be radioactive:\n\n* It's contaminated with something radioactive. Iodine 131 is a pretty common after nuclear reactor accidents. I would call this water contaminated with radioactive material rather than irradiated, but apparently my version is too long for a headline.\n\n* The atoms in the water itself contains unstable isotopes. Both Hydrogen and Oxygen have unstable isotopes. The most common of these is Tritium (or ^3 H) which is a hydrogen with two extra neutrons in the nucleus. This isotope occurs naturally, but it can also be produced if water is exposed to intense neutron radiation for long periods of time.\n\nThe word \"irradiated\" can mean several different things. Inside a nuclear reactor a lot of the radiation is neutrons. When someone talks about irradiated food that's just x-rays which can't create new isotopes so can't make water or food radioactive.\n", "Unstable nuclei will eventually decay and emit radiation. If something is bombarded with neutrons, some of them are captured by the nuclei, which can become unstable. In the case of water, it's possible that some could be captured to produce tritium, which is radioactive.", "Radioactivity is really a property of the nucleus of an atom. Unstable nuclei will decay and throw off pieces of itself (alpha, or neutron radiation) and electrons (beta radiation) and photons (x-ray or gamma ray radiation).\n\nThere are two ways water can be radioactive:\n\n* It's contaminated with something radioactive. Iodine 131 is a pretty common after nuclear reactor accidents. I would call this water contaminated with radioactive material rather than irradiated, but apparently my version is too long for a headline.\n\n* The atoms in the water itself contains unstable isotopes. Both Hydrogen and Oxygen have unstable isotopes. The most common of these is Tritium (or ^3 H) which is a hydrogen with two extra neutrons in the nucleus. This isotope occurs naturally, but it can also be produced if water is exposed to intense neutron radiation for long periods of time.\n\nThe word \"irradiated\" can mean several different things. Inside a nuclear reactor a lot of the radiation is neutrons. When someone talks about irradiated food that's just x-rays which can't create new isotopes so can't make water or food radioactive.\n" ] }

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{ "a_id": [ "c4melww", "c4mem9i", "c4mexgy" ], "score": [ 6, 2, 3 ], "text": [ "No. Some fusion might occur but it would not be self-sustaining.", "Nope. you'd get localized shock waves, and disruption of the conditions, but Jupiter does not have enough mass to begin or sustain fusion at its core. ", "Jupiter needs to be about ten times as heavy to initiate deuterium fusion, and about 80 times as heavy to initiate bona fide hydrogen fusion and become a star. A nuclear bomb would not initiate either." ] }

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{ "a_id": [ "dgdyn71" ], "score": [ 17 ], "text": [ "It does reduce the spice. Spicy chili peppers contain an oil called *capsaicin* which gives the spicy flavor. Lemon juice has acids in it, and the acids neutralize the oils, which reduces the spice. " ] }

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{ "a_id": [ "e74w67t", "e74wgk8", "e74x2dj", "e74xia5", "e75ca7a", "e76mp4v" ], "score": [ 7, 7, 8, 2, 3, 2 ], "text": [ "_URL_0_\nBecause it has had a awfully long time to build up before humans Started using it. Or even before we started existing.", "There was A LOT of ancient life, a number of which grew to massive sizes (many insects being as large as or larger than people) due to the abudance of oxygen in certain ages, which means there was A LOT of organic matter. At least that's my understanding as to why there could be so much oil", "Hundreds of millions of years of swamps doing swampy things... \n\n...like sucking down carbon from the atmosphere and sinking it in anoxic environments where it turns to kerogen and then to fossil fuels. \n\nThe Carboniferous period predated the Permian Triassic Mass Extinction Event —aka: The Great Dying— by laying down gigatons of Carbon... which turned to coal, oil, and methane... huge volumes of which were burned by the EXTREME volcanism of the Siberian Traps. \n\nLike 96%+ of the tree of life went extinct. \n\n[Burning Fossil Fuels Almost Ended Life on Earth](_URL_0_) ", "Much of it comes from a epoch called the Carboniferous period. It was a time when plants first took over land and many of them grew to huge sizes. They also existed before the bacteria and fungi that are good at breaking down cellulose and other structural materials of the plants evolved and so they decayed very slowly when they died. Many being buried in mud and soil before they decayed which changed how they decayed turning much of their volume into coal, oil and other fossil fuels. ", "Most sedimentary rocks contain at least a small amount of organic matter that consists of the preserved residue of plant or animal tissue. It's rocks and sediment that contain a larger amount than usual which may go on to become coal or oil, and there's been a lot of time for this to happen. There's some confusion in other answers, so to clarify: **coal is generated from terrestrial organic matter (plants, mostly trees), and oil/gas is generated from marine organic matter (plankton which dies and sinks to the seafloor).** Insects, dinosaurs and any other animals have never been a significant source of organic matter for oil or coal. \n\n\nWhen the tissue of organisms decay, particularly in an oxygen-deficient environment, organic degradation may not be complete; more decay-resistant parts of organic substances such as cellulose, fats, resins, and waxes are not immediately decomposed. If a depositional basin happens to be an oxygen poor environment - such as a restricted basin, stagnant swamp, or bog - or if the supply of organic matter is so great that it simply overwhelms all available oxidants, then decay-resistant organic matter may be preserved long enough to become incorpo­rated into accumulating sediment. \n\n\nContrary to what other answers here might have said, this in itself does not take hundreds of millions of years - it can be quite a rapid process of decades to hundreds of years. Once buried, this is when it may persist for hundreds of mil­lions of years, and given the right temperature and pressure conditions, may transform into a fossil fuel. \n\n\nConsidering that the Earth has had over half a billion years of the sort of life and the range of environments which may produce oil, it's not really a surprise that there's a fair bit of the stuff knocking around, though it's quite an art form to find viable deposits. \n", "Plankton. There is an insane amount of biomass in plankton. What's really crazy is that it generally takes anoxic conditions and slow to stagnant water to form oils, which means that most of the biomass probably didn't undergo the transformation to oil." ] }

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[ [ "https://pbs.twimg.com/media/ByOd-TVIYAApSKS.png" ], [], [ "https://www.theatlantic.com/science/archive/2017/07/a-road-trip-to-the-end-of-the-world/532914/" ], [], [], [] ]

{ "a_id": [ "c2ypnfj", "c2ypnfj" ], "score": [ 8, 8 ], "text": [ "In short you're correct: a management consultancy does spend a lot of time investigating a company, then makes a number of recommendations to senior staff on how to improve their business.\n\nNot all management consultants are equal. The senior consultants and partners spend a lot of time with senior members of the company with which they're working, discussing performance and strategies.\n\nMid-level consultants tend to hold interviews with mid-level managers to understand the company and recognise problems. They may also supervise a team of junior consultants.\n\nThe junior consultants spend a lot of time typing up notes, fiddling with PowerPoint slides and ordering dinner because they're having to work very late.\n\nDepending on ability, performance and luck it takes about 5 years and an MBA to move from junior to senior.", "In short you're correct: a management consultancy does spend a lot of time investigating a company, then makes a number of recommendations to senior staff on how to improve their business.\n\nNot all management consultants are equal. The senior consultants and partners spend a lot of time with senior members of the company with which they're working, discussing performance and strategies.\n\nMid-level consultants tend to hold interviews with mid-level managers to understand the company and recognise problems. They may also supervise a team of junior consultants.\n\nThe junior consultants spend a lot of time typing up notes, fiddling with PowerPoint slides and ordering dinner because they're having to work very late.\n\nDepending on ability, performance and luck it takes about 5 years and an MBA to move from junior to senior." ] }

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{ "a_id": [ "c9u22jd" ], "score": [ 18 ], "text": [ "Because giving it up was a hugely important bargaining chip for peace with Egypt. No one really regarded it as part of Israel (the way the West Bank is), though there were people there who were less than thrilled about being kicked out. Making it demilitarized allowed for Israel to retain a buffer, while still getting peace with Egypt." ] }

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{ "a_id": [ "c26zx3y", "c270smr", "c271cij" ], "score": [ 2, 6, 5 ], "text": [ "Just some of my random thoughts on it:\n\n If there were water where there is now more or less empty space then all planets, solar systems and galaxies would be connected/accessible to one another instead of isolated systems. Life wouldnt be bound to planets but could live almost anywhere. \n\nThen again a large part of space would be frozen water as well. \n\nTheres also the question of what exactly would happen to stars if they are surrounded by water\n\nAlso, if there had always been water everywhere then that would change the outcome of how everything in the universe formed. There might be no planets or stars, supernovas, comets or anything we know today, but rather something completely different. Either everything is just one big block of ice, or something like a big connected ocean might form. ", "Your daughter is in good company with that wondering. One of the very first scientists was a Greek guy named Thales, who held that the primary essence of every substance was water.\n\nWhat do you mean by \"what if?\" Do you mean \"If the universe were all water, what would it be like?\" Or do you mean \"How do we know the universe is not made of water?\"", "The Big Bang Theory supposes that, at some point in the universe's early history, the energy in its creation began condensing into matter, in the form of (among other things) hydrogen. From there, the relatively stable hydrogen gas began coalescing (by gravitation forces) into stars and galaxies. \n\nPresumably, a universe permeated with water would show very similar behavior. Stars would form (with heavier cores due to the oxygen in water's molecular structure) with different lifecycles. In between the stars would be the typical vacuum of space, left from where the gravity swept out all the water form the stars. \n\nIn short, a universe of all water is not a \"steady-state solution.\" (Just like a vertical, single-file column of ping-pong balls on a table is not a \"steady-state.\") As time progresses, gravity will rearrange things. " ] }

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[ "http://www.reddit.com/r/AskReddit/comments/ivnt4/reddit_science_people_my_6_year_old_would_like_an/" ]

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{ "a_id": [ "d1gonlo" ], "score": [ 2 ], "text": [ "Car dealerships are independent businesses who have franchise agreements with the various car makers they sell. They purchase the vehicles through the manufacturers at the invoice price, but there are often other mechanisms for the dealers to make money from the sale, such as manufacturer holdbacks, quota bonuses, and other incentives. So even if a dealer sells a car \"at invoice\" they may still be making 3-5% of the cost in profit. Obviously then, if they sell for above invoice, they make more profit. Then there are the additional revenue streams that the finance manager tries to sell you on, like extended warranties, wheel protection, etc. that are all high margin products (same reason Best Buy always tries to sell you the extended warranty). And then there is the financing, with bounty going to the dealer when they go through the auto makers' credit arm. But most dealers actually make the most of the profit form the service part of the dealership, whether repairs covered under warranty that the car maker reimburses for, or repairs/service that are paid directly by the customer." ] }

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{ "a_id": [ "dhblp8k" ], "score": [ 3 ], "text": [ "What timeframe are you refering to?" ] }

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{ "a_id": [ "e720vu1" ], "score": [ 8 ], "text": [ "About 100-1000 femtoliters.\n\n & #x200B;\n\nBut it's a pretty hard thing to answer. The cell with the smallest volume that I know of is the sperm cell, with about 20 femtoliters (fL). The most numerous cell in your body is the red blood cell, and it has a cytoplasmic volume of about 100 fL. But a fibroblast has a volume of 1000 fL, a fat cell has a volume of about 100,000 fL, and a egg cell (oocyte) has a volume of about 1,000,000 fL.\n\n & #x200B;\n\nSo how small of a volume is 100 femtoliters? Well, in 100 femtoliters, there is only a trillion water molecules. I know a trillion is a big number, but the fact that we even have a common word for the number of molecules in that volume tells you it's pretty small. " ] }

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{ "a_id": [ "cg519bs", "cg519kd", "cg52ze7", "cg53f03", "cg53r6r", "cg59byu" ], "score": [ 4, 6, 3, 4, 2, 2 ], "text": [ "They're interviewing a bunch of other candidates to see who's best.", "Hiring an employee is a big investment. If there are lots of good options, then you want to make sure you're making the right one.", "1) We have to go through whatever resumes we collect during that time period, and select from those which candidates we think are worth interviewing. \n2) We have to schedule and conduct interviews of all of those candidates. \n3) We have to do decide which candidates we might want to hire. \n4) We have to do background checks on those candidates. Some places also do a credit check (which I understand but disagree with). \n5) We then extend offers. \n6) Depending on how 4 & 5 go, we might have to do another round of interviews.", "Are you asking why it takes so long for them to get back to candidates? Keep in mind that they often won't tell candidates who did not get the job until they have definitely filled the role. So they may offer it to one person who takes a week to respond and then decides to decline or wants too much money. So they offer it to the next person and that person takes some time to decide. Keep in mind that the top candidates may have other offers so things take time even after they have finished interviewing.", "There are a lot of good points here. But I'm guessing it's because time moves slower for a prospective employee waiting to hear from an employer. ", "I understand the criminal background checks. But why would an employer need to do a credit check?" ] }

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{ "a_id": [ "d33yw8z" ], "score": [ 2 ], "text": [ "Because the senate doesn't give a shit about actual government duties and only cares about their own partisan political ideologies and abusing their powers as much as possible in order to advance those particular political ideologies." ] }

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{ "a_id": [ "cpav2j9" ], "score": [ 2 ], "text": [ "hi! hopefully some of the historians in antiquities will drop by with more info, but you may be interested in a few related posts\n\n\n* [How do we know what years certain pre-gregorian historical events happened in?](_URL_4_)\n\n* [How certain are we of what year it is? Were there every any disagreements, like during the Dark Ages or afterwards, of the exact year?](_URL_2_)\n\n* [If an event is recorded to have occurred on a particular date, and I ask you to say with 100% confidence how many days have elapsed since that event, what is the oldest era for which you can do this?](_URL_3_)\n\n* [What is the earliest recorded date that we can determine accurately?](_URL_5_)\n\n* [What is the earliest reliable documented event in human history?](_URL_0_)\n\n* [How do historians work with dates from different calendars? Do you have some kind of unified calendar?](_URL_1_)" ] }

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[ [ "http://www.reddit.com/r/AskHistory/comments/q944u/what_is_the_earliest_reliable_documented_event_in/", "https://www.reddit.com/r/AskHistorians/comments/2lkip2/how_do_historians_work_with_dates_from_different/", "https://www.reddit.com/r/AskHistorians/comments/xww2c/how_certain_are_we_of_what_year_it_is_were_there/", "https://www.reddit.com/r/AskHistorians/comments/1vr3br/if_an_event_is_recorded_to_have_occurred_on_a/", "https://www.reddit.com/r/AskHistorians/comments/1obrab/how_do_we_know_what_years_certain_pregregorian/", "http://www.reddit.com/r/AskHistorians/comments/19pgf6/what_is_the_earliest_recorded_date_that_we_can/" ] ]

{ "a_id": [ "e1comu5" ], "score": [ 2 ], "text": [ "Hi there, I essentially answered a similar question to yours [here](_URL_1_), and linked to an earlier answer on some more of the legal changes [here](_URL_0_). The legal changes in particular would have had a genuine impact on the day-to-day life of the English people, especially as the legal system turned heavily from restorative to punative justice." ] }

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[ [ "https://www.reddit.com/r/AskHistorians/comments/6bale9/how_did_the_norman_conquest_of_england_impact_the/dhl77kj", "https://www.reddit.com/r/AskHistorians/comments/8tf1o4/z/e17fsg8" ] ]

{ "a_id": [ "c46qo24", "c46qqyn" ], "score": [ 9, 4 ], "text": [ "Although what causes pedophilia is not yet known, beginning in 2002, researchers began reporting a series of findings linking pedophilia with brain structure and function: Pedophilic (and hebephilic) men have lower IQs, poorer scores on memory tests, greater rates of non-right-handedness, greater rates of school grade failure over and above the IQ differences, lesser physical height, greater probability of having suffered childhood head injuries resulting in unconsciousness, and several differences in MRI-detected brain structures. They report that their findings suggest that there are one or more neurological characteristics present at birth that cause or increase the likelihood of being pedophilic. Evidence of familial transmittability \"suggests, but does not prove that genetic factors are responsible\" for the development of pedophilia.\n\nAnother study, using structural MRI, shows that male pedophiles have a lower volume of white matter than a control group.\n\nFunctional magnetic resonance imaging (fMRI) has shown that child molesters diagnosed with pedophilia have reduced activation of the hypothalamus as compared with non-pedophilic persons when viewing sexually arousing pictures of adults. A 2008 functional neuroimaging study notes that central processing of sexual stimuli in heterosexual \"paedophile forensic inpatients\" may be altered by a disturbance in the prefrontal networks, which \"may be associated with stimulus-controlled behaviours, such as sexual compulsive behaviours.\" The findings may also suggest \"a dysfunction at the cognitive stage of sexual arousal processing.\"\n\nBlanchard, Cantor, and Robichaud (2006) reviewed the research that attempted to identify hormonal aspects of pedophiles. They concluded that there is some evidence that pedophilic men have less testosterone than controls, but that the research is of poor quality and that it is difficult to draw any firm conclusion from it.\n\nA study analyzing the sexual fantasies of 200 heterosexual men by using the Wilson Sex Fantasy Questionnaire exam, determined that males with a pronounced degree of paraphilic interest (including pedophilia) had a greater number of older brothers, a high 2D:4D digit ratio (which would indicate excessive prenatal estrogen exposure), and an elevated probability of being left-handed, suggesting that disturbed hemispheric brain lateralization may play a role in deviant attractions.\n\nWikipedia", "All kinds of things don't make sense. Biological systems are cludged together from parts that were designed for something else. Add culture on top? And it's a quagmire of things that don't always have a purpose or function.\n\nAs an example, why do men have nipples? Answer: Because males and females are developmentally linked, you couldn't get rid of male nipples without impacting females.\n\nWith any kind of sexual attraction thing that doesn't seem to make sense, it's likely that it's just bad luck at the edges of an effect that produces good results on average. " ] }

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{ "a_id": [ "dly00el", "dly0637" ], "score": [ 2, 2 ], "text": [ "So in your world slavery was the end of the matter?", "The effects of US Slavery are still seen today. It's not about the history of slavery in other countries. That doesn't directly affect our culture the way our slavery did. \n\nYou can't say that robberies didn't start in the US, so criminals can't be blamed for robbing today.\n\n > why are white Americans viewed as evil when slavery started in Europe in the 1400s\n\nI think that's a skewed viewpoint. Rational people wouldn't view all white people as evil. Who is saying this?" ] }

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{ "a_id": [ "dj4mkq8", "dj4ngi4" ], "score": [ 3, 3 ], "text": [ "Obviously, there is always a ton to be said on this sort of question, but you might find [this](_URL_0_) response by /u/Cosmic_Charlie informative", "You will be interested in a series we ran a year ago on finding and evaluating sources, particularly parts [1](_URL_0_) and [2](_URL_1_).\n\nThese both feature several of our flaired members discussing where to find the best sources, how to evaluate books, and how to get the most out of secondary sources." ] }

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[ [ "https://www.reddit.com/r/AskHistorians/comments/3larxd/how_can_a_layman_tell_how_reliable_a_source_is/cv4sgdy/" ], [ "https://www.reddit.com/r/AskHistorians/comments/3t1z25/monday_methodsfinding_and_understanding_sources/", "https://www.reddit.com/r/AskHistorians/comments/3tz8wo/monday_methodsfinding_and_understanding_sources/" ] ]

{ "a_id": [ "daabjqn", "daac94m", "daahc3c" ], "score": [ 7, 2, 5 ], "text": [ "The solar sail can either absorb the light (so the sail gains the momentum of the photon it asborbs), or better yet, reflect the light, reversing its momentum. By conservation of momentum, the sail then gains two times the photon's momentum.\n\nThis is completely analogous to experiments you might do with, say, a medicine ball and a person standing on a skateboard.\n", "Great question! This question has already been answered for how momentum is imparted (although as a system it is always conserved), but the \"why\" might also be interesting. You probably know the equation Energy = Mass x (speed of light) squared, or E = mc^(2). In truth, this is not the full equation! The full equation for how mass and energy relate is the [Energy-momentum relation](_URL_0_). The extra term shows that even for massless particles, there is still a momentum (E = pc or Energy = momentum x speed of light). Since a photon is purely energy, it will have a momentum. Of course this is all relativistic, meaning that the object is moving very close to the speed of light, and this momentum \"p\" cannot just be substituted as mass x velocity in an example of say, a baseball being thrown. Hope that helps!", "The light loses energy and momentum when it strikes the solar sail. It doesn't lose speed, though. For a photon, the energy is equal to hf, where h is planck's constant and f is the frequency. The momentum, on the other hand, is equal to hf/c. So the light that's reflected from the solar sail will be a little bit red-shifted comapred to the light that illuminates it." ] }

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[ [], [ "https://en.wikipedia.org/wiki/Energy%E2%80%93momentum_relation" ], [] ]

{ "a_id": [ "fkxrq6x" ], "score": [ 11 ], "text": [ "They don't, it's just a,way of drawing the Periodic Table more compactly. If you wanted the table set out properly as a grid it would have to be an unwieldy long piece of paper. The whole thing really should be split at that point and the La and Ac elements inserted as two long lines. We draw it the way we do for for covenience. If we wanted to, we could also draw the d-block elements similarly.\n\nChemically it's because the order of filling electron orbitals doesn't go simply shells 1-2-3-4-5... For the higher weight atoms, electrons start to fill the higher numbered \"s\" and \"p\" shells before the \"d\" and \"f\" of lower numbered shells have all the electrons they can take. So at the start of the Lanthanides and Actinides the sequence goes back filling in the remainder." ] }

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{ "a_id": [ "cbms9rk", "cbmsuy8" ], "score": [ 2, 10 ], "text": [ "It depends on who is measuring the speed. Notice that speed is a local concept in general relativity. There is nothing stopping objects from *appearing* to move faster than light, if they are far away. This may be more readily understandable in the context of expansion of the universe, but it applies to black holes as well. Only if you are measuring speeds locally does the speed limit of c apply.", "There are two important things we have to remember here:\n\n1. Velocity is a relative quantity. We can't just say, \"That thing is moving at velocity *v*.\" We can only say, \"That thing is moving at velocity *v* **relative to that other thing**.\" I assume you question is then, \"Does an object inside the event horizon of a black hole move faster than c relative to an observer outside the event horizon?\" This brings us to the second important fact.\n\n2. The region inside the event horizon of a black hole **is not part of our universe**. This may sound shocking, but let's think about it. Nothing can cross from inside to outside, so we can never receive any information about it. It is completely inaccessible to us. We might as well say it's outside of our universe.\n\nThus, there's no meaningful way to talk about how fast something *inside* the event horizon of a black hole is moving relative to something *outside* of a black hole since we can never compare their velocities. Now, two massive objects inside the event horizon and in causal contact with each other (that is, they can \"see\" each other) must move at less than c relative to each other.\n\nWe, of course, could ask the hypothetical question, \"Well, if we *could* see inside the event horizon of a black hole, would objects in there be moving at faster than c relative to us?\" To answer that, I'd have to dig out my old relativity textbook and read up on it a lot, but even if it could happen, it wouldn't be a violation of special relativity thanks to the event horizon censorship." ] }

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{ "a_id": [ "chrwk4l", "chrwor3", "chrx0bh", "chrx66m", "chryg7m", "chs0pxn", "chs1bv4", "chs1xa6", "chs2d8b", "chs2ft9", "chs2vsz", "chs324y", "chs38fa", "chs40bj", "chs4218", "chs4d38", "chs5b37", "chs5prc", "chs5wrp", "chs7f9d", "chs7r25", "chs9ay6", "chs9lf9", "chs9upp", "chsbfma", "chsboiz", "chsbv6j", "chsg535", "chsgm5c", "chshpto", "chshxbt", "chsjhuv", "chsjq8w" ], "score": [ 3, 1294, 139, 10, 24, 213, 13, 4, 963, 2, 16, 12, 2, 2, 17, 2, 2, 29, 4, 2, 2, 2, 2, 4, 4, 2, 4, 3, 3, 2, 3, 4, 2 ], "text": [ "I can't speak for all languages, but I'll try to help differentiate between three languages I kinda know: HTML, CSS, and JavaScript. These are mostly used for websites.\n\n**HTML** or HyperText Markup Language is a languages that 'structures' the different parts of a website. They group things up, make tables, basically brings the essentials to the table. **if your website was your body, HTML would be the skeleton.** Laying out the structure, to be built up on eventually.\n\n**CSS** or Cascading Style Sheets is a way of presenting the elements you have created in HTML. This can be done my giving a background the the *elements*, defining a margin or its general location on the page, or, if it's a text element, its font or text color. **If your website was your body, CSS would be the skin.** applies to HTML, decorating and styling it.\n\nThen there's JavaScript. This is usually a lot more complex than HTML and CSS, and uses logic gates and loops and the like. JScript does the 'behind-the-scenes' work on your websites, such as animations. **If your website was your body, JavaScript would be the organs.** Taking information and processing it in a desired way.\n\nObviously, I'm no expert. I guarantee I'm going to be corrected at least a few tines here, but this is my understanding of each. \n\nIf you're interested, I learnt this (incorrect?) Information with _URL_0_, which was hands-on, colloquial, and very ELI5-y.\n\nEDIT: I'll try to answer any more questions you might have if you ask me.", "Every single programming language serves one purpose: explain to the computer what we want it to do.\n\nHTML is... not a programming language, it's a markup language, which basically means text formatting. XML and JSON are in the same category\n\nThe rest of languages fall in a few general categories (with examples):\n\n1. Assembly is (edit: for every intent and purpose) the native language of the machine. Each CPU has it's own version, and they are somewhat interoperable (forward compatibility mostly).\n\n2. System languages (C and C++) . They are used when you need to tell the computer what to do, as well as HOW to do it. A program called a compiler interprets the code and transforms it into assembler.\n\n3. Application languages (Java and C#). Their role is to provide a platform on which to build applications using various standardized ways of working.\n\n4. Scripting languages (Python, and Perl). The idea behind them is that you can build something useful in the minimal amount of code possible.\n\n5. Domain-specific languages (FORTRAN and PHP). Each of these languages exist to build a specific type of program (Math for FORTRAN, a web page generator for PHP)\n \nThen you have various hybrid languages that fit in between these main categories. The list goes on and on. Various languages are better suited for various tasks, but it's a matter of opinion.\n\nFinally and most importantly: JavaScript is an abomination unto god, but it's the only language that can be reliably expected to be present in web browsers, so it's the only real way to code dynamic behavior on webpages.\n\nEdit: Corrections, also added the 5th category\n\n", "It can be hard to explain the differences between them without getting too technical, but I'll give it a shot.\n\nTo start with, programming languages can be divided into two categories: compiled languages, and interpreted languages.\n\n**Compiled languages** are run through a program called a compiler, which takes the source code and generates a program file (like an .exe). The main advantage of this is that you have a packaged program which usually doesn't have any requirements to run it. The disadvantage is that there's an extra step between writing the code and distributing the program. Languages like C++ and Java are compiled languages.\n\n**Interpreted languages** are run through an interpreter at the time you run them, which processes the code and turns it into instructions for the computer as it goes. The advantage is that you don't have to go through the compilation step (which can take a decent amount of time for large programs); the disadvantages are a) it has to interpret it as it goes, which can take more resources, b) because it doesn't process the program until you run it, it's a lot easier for errors to slip through (compiled programs can check for some of those errors during the compilation step), and c) the person running the program needs the interpreter (whereas only the person *making* the program needs the compiler). Languages like Python and Javascript are interpreted languages.\n\n**Not programming languages**: Things like HTML and CSS aren't programming languages at all; they define things like the structure or style of a web page (or other text), but don't actually tell the computer what to do. The computer reads the markup and decides what to do with it on its own. It's kind of like how Microsoft Word is a program, but even though a Word document *contains* all of the font and layout information, it doesn't mean anything until Word decides how to handle it.\n\nThere are differences between each language beyond, that, as well. One of the most-cited difference is between C++ and Java: C++ lets you allocate and deallocate memory on your own, while Java handles it for you. What this means is, in C++ you have to tell the program how much RAM you want to use and when you're done using it. This gives you a lot of control over how much memory your program uses, which is great for squeezing performance out of an application. On the other hand, if you *forget* to tell the program that you're done using some RAM, you can run into serious problems. Java deals with the issue by doing all of the memory management for you: it figures out when you're done using a bit of RAM and frees it up automatically. That sounds great, but that extra processing has some overhead, and it's not necessarily fast or efficient compared to doing it yourself, so Java programs can be resource hogs.\n\nThe decision to pick one over the other is based almost completely on what kind of program you want to make. In the game industry, where performance really matters, C++ is still the standard language. For an application where you have no control over the user's environment, Java might be better: the user only needs to have Java installed to run it on pretty much any machine. For something that runs inside a web page, you'd pick Javascript: it's not as fast as something like C++, but web browsers have serious security restrictions on what they can run, so compiled programs are totally out. (And in case you didn't know, Java and Javascript are unrelated.)\n\nThere are other languages with vastly different programming styles that are highly suited towards complex math or AI systems, so programmers might specialize in completely different languages depending on what sort of work they do. There really isn't a \"better\" or \"perfect\" language; they're all tools with different features, and you pick the tool that makes the most sense for the job.\n\n**Edit**: Please keep in mind that this is ELI5! If you want to suggest how I can make this easier for non-programmers to understand, then please do so. If you want to nitpick about how I'm technically wrong about something, please take it to a programming-related sub.", "HTML and CSS aren't programming languages. HTML and CSS are both used to describe a page. The former for the content and the latter specifically for the look and formatting. \n \nProgramming languages vary quite a bit. You mentioned some specific ones that are geared towards web programming. Others include C++, C#, Java, et al. Generally, languages vary in their focus, and each has their strengths. All of them vary in their level of abstraction. \n \nThe abstraction is referred to low or high-level. When you hear people talk about a high-level language then they're referring to one with high abstraction. A low-level language like assembly has low abstraction. \n \nYou can think about it this way. Draw a line with computer readability at one end and human readability at the other. Each programming language is going to sit somewhere between these extremes. Assembly languages are going to be on one end and scripting languages like Python and Ruby are on the other. \n \nA low-level language that is computer readable is going to be harder to program well, but it'll perform better and provide a better degree of control. A high-level language is going to be easier to program, but it'll perform worse, because of the overhead imposed by the abstractions; and it'll provide less control which is lost in the process of making it easy to program. \n \nThat doesn't mean high-level languages are worse. Having the best possible performance isn't always the most important consideration. And typically you don't need to exert complete control over different functions. The abstractions imposed by higher-level languages typically perform well enough and provide the basic needed functionality for most programs. And in the process they take a lot less time to bring to market.\n", "There are many different ways in which two programming languages can differ from one another. Note, that I'll try to limit this to general purpose languages, to exclude things like markup languages (like HTML) which do specific things, like describe what webpages should look like. I'll talk about one that is very dear to my heart and which is a kind of very fundamental and essential difference between languages: \n\n**Paradigms:** \n\n*imperative*: Most languages are, first and foremost, imperative. Python, Ruby and Javascript seem to fit this bill. There's alot of state you keep track of, like numbers for example, and you update them in a number of steps. It's like a recipe. You give a list of instructions. The computer does one after the other until there's a cake there. \n\n*declarative*: Haskell is a good example of a declarative language. You give definitions of things. There's no (or very little) state. The computer pieces together definitions to tell you what you want. It's a hard mindset to be in and hard to explain without more concrete examples. \n\n*logic*: some programming languages, like prolog, allow you to give a computer a list of constraints, and it will just find something obeying the constraints you layout. I don't have much experience with this. \n\nI'm not going to be able to give a full detailed answer, but the thing to remember is this: at the end of the day the computer will execute a program which is just a list of ones and zeroes. Programming languages are for people, both to let them write those zeroes and ones easier and to let them communicate programs to each other in a way they can understand. Some languages are really different. They have completely different paradigms. Even though the most common way is to provide a sequential list of instructions, there are other ways as well. Even with one one paradigm, languages differ from each other in that they each have their own ways of doing things. One language might be better suited for a particular job. Some people may prefer one language to another because they like the way it does stuff or think it's beautiful. The code one language generates might be faster. Or better at some individual thing. Each language, in addition to the technical specifications, has a group of people who write code in it and therefore its own customs. Programming languages are still for people. They're not *that* fundamentally different from natural language. ", "This is ELI:5, guys come on.\n\nThe difference in programming languages is like the difference in human languages. You're just trying to describe concepts to someone and that works differently in different languages.\n\nPython:Javascript::English:German\n\nIn both English and German, you can describe the concept, the idea of \"being happy because something terrible happened to someone else.\" That's how you describe that concept using the English language. The German language has this much better way to handle it, and you can just say \"schadenfreude\". You can also just combine words into longer words in German, but English is all about the spaces and punctuation. \n\nIt's pretty much just syntax sugar the whole way down. Even compiled vs. non-compiled are like English vs. French. One language is full of bullshit, the other is regulated by a body that came up with their own equivalent of \"email\" because saying \"email\" was denigrating to them.", "There's a lot of what seems to be CS undergrads and debates that are going beyond the scope of your question.\r\r\rDifferent problems call for different solutions using different technologies and different languages. Languages' strengths and weaknesses are entirely relative to the purpose of the application.\r\r\r\"If the only tool in your toolbox is a hammer, then everything looks like a nail.\"", "The top few parent comments ITT are very good, but otherwise there are some very confused/bored five year olds out there.", "Like human languages, programming languages really just boil down to different ways to express ideas & actions. \n\nSome of the differences are between languages are minor. I.e., if you want to display text on the screen, all of these do the same thing in various languages:\n\n print \"Hello Reddit\"\n printf \"Hello Reddit\"\n say \"Hello Reddit\"\n cout < < \"Hello Reddit\"\n System.out.print(\"Hello Reddit\");\n\nWhy such minor differences? Because languages are written by humans. And humans are human. Which is to say petty at times.\n\nOn the other hand, some of the differences are much larger. For example, one major is something called \"memory management.\" \n\nThink of yourself a computer for a moment. You're going to be told a lot of different things. More than you can remember in your head. So what do you do? \n\nYou get a notebook. You decide on each line, you'll write down each thing you need to remember. Be it Alice has $100. Or Bob's favorite color is red. Whatever it may be, each thing takes a line. How many things can you remember? That's determined by how many lines in your notebook. \n\nOf course, after a while some things are no longer needed. The activity that required to remember Alice had $100 ended. So you can erase that line & reuse it. \n\nEach of those lines is like memory in a computer. Some programming languages require you (the programmer) to explicitly say \"I'm done with lines 134 - 150. You can use them for something else.\" Other languages have ways to figure it out automatically. \n\nWhy not always figure it out automatically? Well, it's expensive. It turns out you need to keep track of a few other things & periodically take time to check if something is used. Maybe that's okay, but it's also possible you're doing something critical -- say running a nuclear power plant or the instructions for a pacemaker -- where it isn't. It's basically comes down to a tradeoff between convenience & performance. \n\nWhich is another major difference between languages: Do you aim to optimize how fast it takes the developer to write a program? Or to optimize how the program uses the physical resources of a machine? (E.g., its CPU, memory, etc.)\n\nThere's lot of other tradeoffs like these. Other tradeoffs are how well does it work with other computers on the network? How well does it let me create a graphical interface? How are unexpected conditions handled? \n\nAnd in a nutshell, each language makes a different set of decisions on tradeoffs. \n\nWhich is best for what? Well, that's subjective. Ask 100 different programmers & you'll get 100 different answers.\n\nFor example, my employer tends to 4 primary languages: C++, Java, Go, & Python. C++ is great for problems that need to handle a lot of concurrent activity. (I.e., things that need to \"scale.\") Think of problems where 100,000 people are sending a request a second. Go is good at these problems too. \n\nJava is good for when there's complicated business logic. Think of problems like figuring out how much tax you need to charge, which is going to vary not just on the state, but even the city or zip. Python is good when you need to put something together quickly. Think of problems where I have a bunch of data & I need to a one-off analysis to tell me certain characteristic. \n\nOf course, those are far from the *only* problems each language solves, but it gives a sense of it.\n\n\n\n\n\n\n", "I'd probably break it down to 4 types of programming languages.\n\n1. Object Oriented (Java or C++)\n2. Logical Programming (Prolog or LISP)\n3. Functional Programming (Haskell or LISP)\n4. Declarative (SQL)\n\nAs you can see, some languages can be classified under multiple classes. I'd describe what each type means but you're 5 and you can do your own damn research.\n\nAll I really wanted to say was that the reason there are so many languages is because each language is good at doing \"something\" better than the other. You could make a text file and a java program to store all of your shit. Or download a database management system, learn SQL, and tell the DBMS what you want to insert/edit/delete saving time/money. You could make an AI in C++, but you'll be missing out on the powerful logical programming Prolog has to offer.\n\nSome languages are easier to \"read\" than the other. And some languages are just a pain in the ass to program in. Seriously, look at the assembly code in x86 Windows for Hello, World.\n\n .486p\n .model flat,STDCALL\n include win32.inc\n \n extrn MessageBoxA:PROC\n extrn ExitProcess:PROC\n \n .data\n \n HelloWorld db \"Hello, world!\",0\n msgTitle db \"Hello world program\",0\n \n .code\n Start:\n push MB_ICONQUESTION + MB_APPLMODAL + MB_OK\n push offset msgTitle\n push offset HelloWorld\n push 0\n call MessageBoxA\n \n push 0\n call ExitProcess\n ends\n end Start\n\nDo you really want to type all of that shit out? Functional programming languages are crazy powerful because so few lines can do so much. Here's quicksort for example:\n\n quickSort :: Ord a = > [a] - > [a]\n quickSort [] = []\n quickSort (x:xs) = quickSort [a | a < - xs, a < x] ++ -- Sort the left part of the list\n [x] ++ -- Insert pivot between two sorted parts\n quickSort [b | b < - xs, b > = x] -- Sort the right part of the list\n\n3 fucking lines to sort any list in O(n log n) But of course there's trade offs. Fucking hard to read that shit, eh? Imagine working on a team and reading one page of that code that someone else wrote and communicating what it does to other team members.\n\nThere's basically as many programming languages as there are... languages. Pick one (I'd recommend Java) and play with it.", "There are lots of different programming languages because there are lots of different things you can make computers do.\n\nFor example:\n\n* **HTML**: Used to build simple websites and tell a web browser what to show on the screen.\n\n* **Python**: A very popular language designed to be beautiful, flexible, and powerful while still being easy to read and easy to write. It can be used on lots of different kinds of computers, not just Windows PCs. It can be used to make programs do extra things, add new parts to a game, build websites, and can be used to easily tell computer how to do repetitive tasks.\n\n* **Ruby**: was invented because lots of other languages were too complicated and messy, and Ruby tries to be simple.\n\n* **PHP**: Was designed to be unrestricted so anyone can contribute to make the language better. It was made so you can easily make websites talk to databases, and do much more complicated things which cannot be done by HTML.\n\n* **Javascript**: was invented as a way to make websites do more things that HTML couldn't do by itself. It isn't the same thing as Java.\n\n* **C**: An older language that is still used today, and is the predecessor to C++. It was invented to address the limitations of very early programming languages. It is complicated and easy to make big programming mistakes with.\n\n* **C++**: A very fast, complex, messy looking language which is extremely powerful and flexible, but you can easily make buggy programs if you don't know how to use it properly.\n\n* **Visual Basic**: An adaptable, easy to learn language made up by Microsoft specifically for Windows and other Microsoft products.\n\n* **Java**: Made by Sun Microsystems, designed to be used across many many different electronic devices, like modems, PCs, home applicances, robots, car audio head units, mobile phones, etc\n\n* **C#**: Tries to copy the way Java and C++ are written to make it easier for people to pick up, but tries to be simpler and easier to learn than Java and C++\n\n* **Lisp**: This is a family of similar languages which were born from a much older language. The original Lisp was designed mostly for mathematical purposes, but it has become much more flexible since. It is highly influential in the field of computer science, and its strength comes from its clever, elastic syntax (syntax is like grammar for programming languages).\n\n* **MATLAB**: Designed for use with mathematical scenarios, often used by engineers and scientists.\n\n* **SQL**: Designed to talk to databases. It is like a \"search language\" which you can use to find exactly what you need in a database. It is also used to add information to databases.\n\n* **Assembly**: A very complicated language that is used to \"talk to the CPU\" in a much more direct way. You have to think like a computer to use this language, and it is very difficult to read. Fun fact: the original Rollercoaster Tycoon was programmed by Chris Sawyer using only Assembly, which would have taken a long long time but made the game very efficient and fast.", "In a sense, all programming languages* do exactly the same thing. They describe how to go about performing particular computations. In general, if it's possible to write a program in one language, it's also possible to write that program in any language because we can prove using maths that they can all do the same things. (This is called being [\"Turing complete\"](_URL_0_))\n\nThe differences between programming languages comes down to a few factors: \n\n* Speed: Some programming languages tend to run much faster than others. One major factor in this tends to be whether the language is \"compiled\" (pre-processed to turn it into machine instructions) or \"interpreted\" (turned into machine instructions just before they're run every time). C tends to be very fast because it's already pretty close to the instructions that the computer is actually running (assembly code) and can be very heavily optimized in the compilation process. Languages like Python and JavaScript tend to be much slower because they're (usually) interpreted and very far removed from what's happening at the machine level. \n\n* Ease of writing: Some languages tend to be much easier to write in general than others. Most high-level languages (e.g. Python, JavaScript, Ruby) provide you a lot of really nice tools that allow you to write code very fast and easily. The language will also handle a lot of stuff that you'd need to micromanage in a lower-level language (e.g. C, C++) like memory management. They're also pretty flexible in terms of what they allow you to do compared to some more strictly-defined languages (e.g. Java). \n\n* Style: This relates to the above, but there are a lot of different styles of programming languages, and some people have preferences working with some versus others. One example is static- vs dynamic-typing; whether you have to explicitly declare what all of your variables are and what they can be used for (C, Java), or whether the language will just figure it out for you (Python, JavaScript). Another is imperative vs declarative; whether you tell the computer all the steps that it needs to take to solve the problem (most languages), or whether you just describe what you want it to do and have it figure it out. Kind of. It's pretty of weird. Then there are things like \"functional\" languages, where functions are treated the same as any other kind of data and can be passed around (Haskell, ML, JavaScript); object-oriented languages, where everything is an \"object\" that both has data stored in it and has a set of operations associated with it (C++, Java), etc. Basically, these are all choices the designers of the language made that aren't necessarily objectively good or bad but make some people like the language and some dislike it. \n\n*As others have mentioned, there are things that might seem like programming languages but really aren't. These include things like: \n\n* HTML: Defines the structure of a webpage\n\n* SQL: Describes information to grab from a database; newer versions can kind of be considered real programming languages.... Kind of....\n\nThese aren't actual programming languages in the sense that they're not describing how to do any computation per se. ", "Programming languages are divided up along a number of lines.\n\n\nHow they are executed:\n\nPrograms are either run directly by the hardware of the machine, or by a software layer between the program and the machine. \n\nExamples of languages that translated ahead of time to run directly on the hardware are C/C++, Pascal, Fortran, Common Lisp, Haskell, Forth... the list goes on.\n\nExamples of languages that are run by a software layer include Python, Perl, Ruby, Java, JavaScript, C#, Lua, Common Lisp... again the list goes on (and yes there is overlap, it's possible to do either).\n\nPrograms compiled to run against the hardware are usually faster than those that are run by a software layer, but that's not always the case, Java and C# are quite performant (easily within an order of magnitude of their native counterparts).\n\n\nThe Type system:\n\nIn simple terms this dictates what parts of the program can do to other parts of the program. The major examples are Untyped, statically typed, dynamically typed.\n\nAn example of an untyped language is x86 object code (the language that runs on Intel's CPU's). This language treats everything as a series of 1's and 0's. Even the instructions are just 1's and 0's, there is no concept of a letter or a number, it's just groups of 1's and 0's and different operations on them.\n\nAn example of a statically typed language is C, C knows about numbers, and different groups of numbers in a certain layout (a struct). It also has functions, which are groups of instructions. An example of the type system in action is that it will not let you call a function that expects a single number with an argument that is a group of numbers.\n\nAn example of a dynamically types programming language would be one of the Lisp family. These languages will allow you to call a function that expects a single number with an argument that is a group of numbers, the program will then fail when it is run because the function doesn't know what to do with a group of numbers.\n\n\nThe Paradigm: \n\nThis is the basic structure of the language. Examples are Imperative, Functional and Logic programming. Other people might include object oriented in this list, but I see it as largely orthogonal, it's just a way of organising things, not anything fundamental.\n\nImperative languages are comprised of instructions, they are run one at a time, one after the other. They may jump around a bit, but they will always execute one instruction after another.\n\nFunctional languages work differently, a functional language, like Haskell for instance, aren't a list of instructions that go and change data, they say what the input data is and what the output data should be, the language then goes off and does that for you.\n\nLogic programming languages, such as prolog work differently again, a prolog program consists of a set of rules. When you give the program some input it will try and match the input to it's rules and from there give you anything that matches your rules.\n\nThe Memory Management Scheme:\n\nLots of languages use a garbage collector, which is a piece of code that runs in every program written in that language. It runs in the background and looks after the memory used by the program. When it detects that a piece of memory is no longer in use it will give that bit of memory back to the operating system so that other programs (or the current program, later) can use it for something else. Java, C#, Common Lisp, Haskell, Python, Ruby, Javascript are examples of languages that have a garbage collector.\n\nOther languages don't have a garbage collector, for example C/C++, COBOL, Rust. These languages rely on the code that looks after the memory being inserted when the program is compiled. This can either be done by the programmer, as in C and Fortran or automatically inserted by the compiler as in (good) C++ and Rust. If the programmer is required to manage the memory and does it wrong, that program will probably not work.\n\nTo directly answer your question:\n\n* HTML: is a markup language, it's used for describing how something should look, it's not a programming language.\n\n* Python, Ruby, Javascript: These are interpreted, imperative, dynamically* typed, garbage collected languages. They are seen as easy to read and write and protect you from a lot of low level details.\n", "If I wanted to tell you something I want you to do, then I'd speak to you in a human language such as English, Spanish, or Russian. Programming languages work the same way, except you're talking to a computer. For example, if I wanted to tell the computer to say \"Hello World!\" here's how you could do it in a few different programming languages.\n\n\nJava:\n\n System.out.println(\"Hello World!\");\n\n\nPython:\n\n print \"Hello World!\"\n\n\nC++:\n\n cout < < \"Hello World!\";", "**This is a joke list of ELI5 differences. If anyone knows the original sauce plese post it.** \n \n***If Programming languages were religions*** \n \nC would be Judaism - it's old and restrictive, but most of the world is familiar with its laws and respects them. The catch is, you can't convert into it - you're either into it from the start, or you will think that it's insanity. Also, when things go wrong, many people are willing to blame the problems of the world on it.\n\nJava would be Fundamentalist Christianity - it's theoretically based on C, but it voids so many of the old laws that it doesn't feel like the original at all. Instead, it adds its own set of rigid rules, which its followers believe to be far superior to the original. Not only are they certain that it's the best language in the world, but they're willing to burn those who disagree at the stake.\n\nPHP would be Cafeteria Christianity - Fights with Java for the web market. It draws a few concepts from C and Java, but only those that it really likes. Maybe it's not as coherent as other languages, but at least it leaves you with much more freedom and ostensibly keeps the core idea of the whole thing. Also, the whole concept of \"goto hell\" was abandoned.\n\nC++ would be Islam - It takes C and not only keeps all its laws, but adds a very complex new set of laws on top of it. It's so versatile that it can be used to be the foundation of anything, from great atrocities to beautiful works of art. Its followers are convinced that it is the ultimate universal language, and may be angered by those who disagree. Also, if you insult it or its founder, you'll probably be threatened with death by more radical followers.\n\nC# would be Mormonism - At first glance, it's the same as Java, but at a closer look you realize that it's controlled by a single corporation (which many Java followers believe to be evil), and that many theological concepts are quite different. You suspect that it'd probably be nice, if only all the followers of Java wouldn't discriminate so much against you for following it.\n\nLisp would be Zen Buddhism - There is no syntax, there is no centralization of dogma, there are no deities to worship. The entire universe is there at your reach - if only you are enlightened enough to grasp it. Some say that it's not a language at all; others say that it's the only language that makes sense.\n\nHaskell would be Taoism - It is so different from other languages that many people don't understand how can anyone use it to produce anything useful. Its followers believe that it's the true path to wisdom, but that wisdom is beyond the grasp of most mortals.\n\nErlang would be Hinduism - It's another strange language that doesn't look like it could be used for anything, but unlike most other modern languages, it's built around the concept of multiple simultaneous deities.\n\nPerl would be Voodoo - An incomprehensible series of arcane incantations that involve the blood of goats and permanently corrupt your soul. Often used when your boss requires you to do an urgent task at 21:00 on friday night.\n\nLua would be Wicca - A pantheistic language that can easily be adapted for different cultures and locations. Its code is very liberal, and allows for the use of techniques that might be described as magical by those used to more traditional languages. It has a strong connection to the moon.\n\nRuby would be Neo-Paganism - A mixture of different languages and ideas that was beaten together into something that might be identified as a language. Its adherents are growing fast, and although most people look at them suspiciously, they are mostly well-meaning people with no intention of harming anyone.\n\nPython would be Humanism: It's simple, unrestrictive, and all you need to follow it is common sense. Many of the followers claim to feel relieved from all the burden imposed by other languages, and that they have rediscovered the joy of programming. There are some who say that it is a form of pseudo-code.\n\nCOBOL would be Ancient Paganism - There was once a time when it ruled over a vast region and was important, but nowadays it's almost dead, for the good of us all. Although many were scarred by the rituals demanded by its deities, there are some who insist on keeping it alive even today.\n\nAPL would be Scientology - There are many people who claim to follow it, but you've always suspected that it's a huge and elaborate prank that got out of control.\n\nLOLCODE would be Pastafarianism - An esoteric, Internet-born belief that nobody really takes seriously, despite all the efforts to develop and spread it.\n\nVisual Basic would be Satanism - Except that you don't REALLY need to sell your soul to be a Satanist...", "A bit late on this, but here's my shot:\n\nThink of it this way: computers have their own, super complex language. It is extremely difficult to express clearly what you want in it. In addition, computers are pretty stupid, so if you make a mistake in your instructions, they won't try to understand what you actually intend, they will just do whatever stupid stuff you just asked.\nSince it is so difficult to express ideas in this machine language, we created translators. They're sort of bilingual: they can understand instructions in one language, and perfectly translate it for you in machine language. The former is what we call a programming language. If you can express ideas in this language, this translator will be able to translate them to the machine.\n\nFrom that point, you have two things to consider:\n\n 1 - The language that this translator understands\n\n 2 - The translator itself. There are various strategies of translation (interpreted languages translate what you tell them sentence by sentence, literally, while compiled languages will take a full book of instructions and translate it in one go into a 'machine-book' of instruction, so that they have some context)\n\nThe first point is usually referred to as the language, while the second is called the implementation. Most often, it is possible to take either approach for any language. But some are specifically designed to be compiled or interpreted. Java or C++ will require you to make very long sentences, with all the context being explicitely stated, so it works much better when compiled. Others, like Python, Javascript... rely on shorter sentences, with context being more often implicit, so you can directly discuss with the computer, with the interpreter sitting in the middle and doing the translation both ways.\n\nThe difference between languages is mainly how you can express complex processes to the computer. As previously stated, computers are incredibly stupid, and require a LOT of explaining for pretty much anything. Some languages, called 'low-level' (e.g. Assembly, C, ...) try to stick to the way computers see things. It takes a bit more work expressing your ideas in this language, because you have to explain EVERYTHING, but you know that the translation will be completely faithful. On the other end of the spectrum, some language, called 'high-level' (e.g. Python, Ruby...) try to be closer to you than they are to the machine: you can express big ideas and concept to them, and they will do all the work of breaking it down into small pieces the computer can understand. Of course, you have no control on exactly how they do this break down, but it is often much simpler when exploring an idea to be able to have this high-level conversation.\nIn the middle, some languages will try to do both, defining both big abstract concept and small concrete tools for better controlling what exactly the computer is doing. \n\nFinally, the other thing to consider is that other humans will look at your code. Some prefer to have it completely broken down to understand exactly what is going on, but most are more comfortable with seeing it in high level languages, where they can get the big picture of what your program is doing without having to get all the details.\n\nNote that this is very subjective too ! Back in the days when programmers where electrical engineers, C was seen as 'high level' because it defined new abstractions, like functions. And you can express some very low-level details of how things should work in Python. The language just gives you a framework for expressing your ideas, and some framework work better than other for expressing different ideas.", "Javascript is the Duct Tape of programming languages. ", "Warning: most of this thread\n_URL_0_", "Low-level languages are used when you care about how every component inside the machine is going to operate. What you produce here is not compiled the way other languages are - you're writing instructions for a specific system architecture and what you write to work on one chip (x86), won't work on another (a Motorola chip)\n\nMid-level languages abstract some components but not others: I don't care about how the CPU and system bus work here, but I do care about memory - that's typical (e.g. C). A compiler takes this and turns into a lower level instruction set so can be compiled to work (normally) on any system architecture - if you're careful.\n\nHigh-level language: I don't care about how the computer does this I just want to describe the solution to my problem and the compiler/interpreter figures out how to turn that into a lower representation the computer can run so it will run \"everywhere\" (I'm simplifying). These are languages like Ruby, Python, Perl, etc.\n\nDifferent high-level languages are designed to describe solutions to problems in different ways. In the same way algebra and calculus are related, it's easier to solve some problems with one more than another (again, I'm simplifying), which is why you will hear talk of \"object-orientated\", \"functional\", \"imperative\", \"strongly-typed\", \"duck-typed\" and a host of other words to describe a language.", "I understand most if not all of these answers, but very little of this is ELI5, especially all the assembly disputes.", "I think the best analogy to give about programming languages is having instructions with different levels of detail.\n\nImagine you were to leave a set of instructions telling an 8 year old child, who didn't speak the local language, how to pick up some eggs from the grocery store. You would want to be as precise as possible; telling him exactly which turns to make, how much money to bring, where to look for the eggs, which eggs to buy, and how to interact with the cashier. This would be Assembly; you have to be very specific.\n\nNow, imagine you are leaving the same instructions for a 25 year old who has lived in the area and often goes grocery shopping. All you'd have to do is leave a note saying \"Buy eggs\". This would be Python; the specifics are taken care of.\n\nThere are some programming languages that have roughly the same level of specificity and just are different ways of saying things (kind of like different human languages).There are also languages that are better at one sort of thing than another (kind of like different vocabularies between fields of study). Most importantly though there are many languages that fall in between the extremes of Assembly and Python, the level of specificity you use really depends on who you're talking to and what you want them to do.\n\n**TL;DR** It's all about how specific you need to be.", "HTML is not a programming language.", "Imagine your computer is a restaurant.\n\nHTML is the hostess / atmosphere of the restaurant. They show you to where you're going, and then you just sit down and look around at things that don't change. Decorations, the tables, etc.\n\nPython, Ruby, PhP, etc \"Server Side\" languages are the kitchen. They do a lot of work, but it's all behind the scenes and you don't really see it.\n\nJavascript is the waiter. They interface between the kitchen and you, but not everything the do requires they go to the kitchen. They can tell you the specials, sing happy birthday, etc. but occasionally have to go to the kitchen to clarify some things or get the actual food made.", "Imagine you are the CEO of a company and you're looking to hire a new plant manager. Different managers have different styles.\n\nThe low level manager micro manages everything, he watches the time clock at every shift change, and employees have to ask him over walkie talkie every time they want to move a box or go to the bathroom. Under his supervision, the plant is very efficient but he has to work 120 hours a week to get the job done.\n\nThe high level manager worries primarily about minimizing the number of hours he has to work. His goal is 5 hours per week per plant. He doesn't do this because he is lazy, he does this because he wants to open and run three other plants. So, he hires a few sub managers, a secretary, a timeclock watcher, a box location watcher. The plant still produces the same amount of end product, but it requires more staff to do it. \n\nBoth managers run all of their policies by you before they get implemented, so the low level manager requires more work at the beginning from you too. \n\nThis is the fundamental tradeoff of programming languages. More up front work from you = more efficient machines. Less up front work from you = less efficient machines (because the machine manages things you otherwise would have to manage yourself, like taking out the garbage)\n\n* The managers are the programming languages.\n* The people working in the plant are the number of operations the computer had to run to complete a task (more operations means slower programs)\n* The policies they run by you is the amount of code you have to write to do something in that language.\n\nNow, there is a second dimension which is how much experience a given manager has in running plants like yours. Is it a website factory, or a bank, or a tiny factory on a small island with very limited access or ability to hire more people? The amount of experience in your domain means the more the manager already knows how to do things you'll want without you having to teach them (i.e. the programming language has features or libraries that solve common problems you're likely to encounter when running a website). And sometimes you'd like to hire a high level manager, but there aren't enough resources to do so, so you have to hire a low level manager or the plants won't be able to run.\n\nAssembly and C are low level languages.\n\nJava, Python and Ruby are high level languages.", "Well, there's a tradeoff with a language -- is it fast to write the code, or is it fast to run the code? Lower level languages can make exceptionally fast code but they take a lot of writing to do it. Higher level languages let you get working code much faster, but they typically run slower. \n\nRoughly from low to high:\n\nAssembly, C, C++, Java/C#, Python/Perl, Javascript\n\nAs for why there's so many... Well, some cater to specific uses... Fortran for math, Visual Basic is typically database front-ends, etc. The other reason is best summed up with this:\n\n_URL_0_", "I would say there are 2 important differences\n\nThe Syntax. Imagine it like this, we phrase sentences in English in a certain grammatical way. But those same grammar rules wouldn't apply if we were to speak Japanese.\n\nNext the Style. This has to do with the words used. Bulgarian and Russian use the same alphabet and some words are similar but in the end they are two different languages. Despite their similarities. So even though Java is influenced by C in it's making, you will find differences when you're writing code.\n\nAlso there are two types of programming languages. Compiled and Scripting (at least in modern use today). Complied languages run via a .exe file on your desktop or any other operating system. These are usually object based languages and require compiling inside of the program you use to write code (the IDE). These languages include Java. Scripting languages don't get compiled, instead they are read line by line in your browser. These languages are Python, Javascript, PHP, Ruby etc.\n\n\nAlso it's good to note that HTML is a markup language not a programming one. Hyper text markup language. This basically means that you're not writing any software with it. You cant program with it. But on the other hand you can make neat looking sites. But keep in mind if you only use HTML to make a site you'll end up with a site that belongs in the 90s. Hope that clears it up! ", "Some great responses here, but a simple way to put it is that languages have different capabilities. A language like Python is great because the language is easy to learn e.g\n\ndef program():\n\n ok = \"This is my sentence\"\n \n print ok\n\nHowever it has less capabilities than a language like Java or C++. You'd tend to think that languages like Python and Ruby are lower end and Java, C, C++ are large scale.\n\nHTML is a web design language, it's fairly easy to learn and consists of tags. I like to to think of it as creating the base/structure of the website. Javascript is pretty much described as adding some live/dynamic aspects to your website.", "no love for MatLab", "Basically everything deduces to c.... The rest is a huge wrapper to make programing easier. Java has a 'garbage collector' or basically it handles memory efficiently. Other than that they are pretty close.", "Why is nobody mention COBOL? I feel so alone :(", "You haven't mastered code until you've mastered Brainfuck! _URL_0_", "I disagree with a lot of the posts here. Though I think it's a pretty common misconception. A programming language is not like a cultural human language. It's a domain specific language. Think of it as jargon, and not a full language. Most computer languages have less than 100 words. The reason there are different ones is because there are different problems. Some are similar enough to be roughly equivalent, but most have a particular field in which they excel. \n\nSailing has a set of words that are similar. Verbs like douse, hoist, trim, ease. Nouns like jib, fo'csle, halyard, sheet. Adjectives like port, starboard, lazy, working, luffing. These are words that aren't used in common English. They're used to sail. Sailors speak them, and they're significantly more efficient than \"Hey that rope attached to the third pulley from the big piece of wood sticking up there. Pull that down until the top of the biggest sail is at the top of the big wooden thing.\" Instead I say, \"Hoist the main halyard.\" In programming it might be halyards[:main].hoist().\n\nThe thing is different domains have a different set of things you want to do. When you're doing drivers, the focus is on speed and efficiency. The syntax of those low level languages is on speed and efficiency. They're not very expressive. They don't have to be. Usually the tasks are relatively simple. You do something basic, but you do it over and over again really really fast. Your graphics driver, your device drivers, your com drivers are all probably like this. They're probably written in C, or something even lower level. Those languages are bulky, and they take a relatively long time to get even a simple task done. They are, however, very very fast once they're written. It's also pretty easy to tell whether they're broken, because there are only a few things they do.\n\nOnce you get to more complex things, it gets more difficult. You have to be more flexible in how to handle data, events and displays. To write those things in the low level languages, you need to spend a lot of time writing the same code over and over. They don't need to be as fast, though, because where you might do the same operation millions of times in a graphics driver, you might only do them hundreds of times in these programs. So as complexity increases, you can make your language more expressive. There are more decisions, but fewer loops. So the jargon shifts towards making the decisions easier to read, at the cost of making the loops slower.\n\nYou continue along that spectrum until you get to the very high level languages like ruby and javascript. These languages are agonizingly slow by comparison, but it's cool because you're often interacting with a human at this level. You're responding to a literal click or a keypress. Those happen one or two a second at the most, not hundreds or millions of times per second. So these languages read like English for the most part. That makes them easier to understand, share the work, and debug when they break. They run more slowly, but you almost never notice, because it's not the program that's slowing things down. It's how fast you as a human can do things.\n\nThat's one axis. Languages differing by task. Top poster is right, that some of the differences are relatively petty. They're cats and dogs things about whitespace, semi-colons, parentheses, etc.,. Even these, though embody different cultural stances. Rubyists generally favor ease of writing over ease of reading. Pythonistas insist that code should be readable no matter who writes it. If you look at python code, it pretty much always looks the same. Three different ruby chunks look like entirely different languages.\n\nSo that's my experience of why they're different.", "Generally the distinction is one of encapsulation. \n\nProgramming languages are like cars. A drive has a couple of levers and a wheel that the car responds to, sometimes he has to fill it with gas, and very occasionally he needs to fill it with money in ways he doesn't understand. The inner workings of the car are very complex, involve a lot of optimizations, and in some cases, sacrifice performance to make this Car/Driver interface less complicated and more robust to driver errors. \n\nWhen I start doing things to the car to increase performance, perhaps the very simplest being replacing the automatic transmission with a manual, I make the car harder to drive, and almost always expose more of the inner workings of the vehicle.\n\nThis follows the general principle that, once things are engineered beyond a certain point, you are unlikely to find improvements which involve no tradeoffs, and the specific set of properties which programming languages are trying to maximize (weighted) the performance of is:\n\n-performing operations\n-writing code\n-debugging code\n-reading code\n-extending code\n-reusing code\n-existence of already written code\n-is the only code which runs on browsers\n-delegation of slow operations to faster languages\n\namong your examples, Python and Ruby are both basically both competing for the spot of: slow, but easiest to use. Ruby is maybe a little slower, and a little more extensible, but you tend to use (C) native libraries to do your really big matrix operations, and they both have good support for that.\n\nJavascript is a shit language, but is the only choice for code that runs in your browser, and HTML is for page layout and object identification and doesn't really count. \n\nSome others: \n\nC is a very small language with enormous libraries, It's not very hard to use, but it is very hard to scale. It can be used to control UI elements, but it's annoying to do so. Ruby compiles to C.\n\nJava is *almost* as fast as C, has lots of library support, is relatively straightforward, and protects against a lot of errors with a very smart compiler. It is very bitchy about what you are allowed to do with the language though, and it needs to know the type of everything at runtime, which is a much more limiting task than it sounds like. " ] }

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{ "a_id": [ "c8hpxdm" ], "score": [ 5 ], "text": [ "Modern televisions have a setting that is usually turned on by default that causes this effect. The way it does it is by looking at two frames in the image, seeing what the differences are, and \"guessing\" what another frame between the two would look like if it was there when the show was recorded. The TV then creates this extra frame, and gives the appearance of the TV show or film being recorded at 48-60 FPS. " ] }

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{ "a_id": [ "e5auhdp" ], "score": [ 8 ], "text": [ "Part 1 (scroll to my reply to this comment to read Part 2):\n\nThe Jordanian motivations go much deeper than the history of the Hussein family and the Palestinians. Instead, one has to first understand the development of Jordan and the development of the state of Israel to understand their overlap.\n\nOn the one hand, Jordan has participated in a number of conflicts against Israel, including joining the efforts to destroy it in 1948, fighting alongside Arab armies in 1967, and participating in anti-Israel actions in various international forums. At the same time, as you noted correctly, Jordan has been far friendlier to Israel than other Arab states, going so far as to propose ways to avoid war in 1948 (King Abdullah proposing in 1947, for example, a nonbelligerency pact to split the Mandate) and to allegedly even warn Israel of an impending attack in 1973 (King Hussein told Golda Meir in a secret meeting on September 25, < 2 weeks before war, that Syria's military had moved to pre-war positions). Evidently, the willingness to cooperate with Zionist leaderships has extended to before King Hussein's father (King Abdullah I) was assassinated by a Palestinian fearing peace with Israel.\n\nThe roots are both strategic and also demographic. Through a variety of factors, Jordanian leaders have been forced to confront that in many ways, their goals overlapped with those of Israel historically.\n\nJordan, for example, was just as concerned as many other Arab leaders with the prospect of taking over the Arab areas of the British Mandate. However, unlike the other parties, Jordan was also party to the best-trained military in the lead-up to the 1948 war. Its well-trained military was counterbalanced, relative to the other Arab states, by the fact that it was (and has been) the smallest country population-wise of the major Arab belligerents since 1948, meaning it also was the least competitive in gross resources to bring to bear. This meant that Jordan was far more willing than the other parties to conflicts with Israel to accept that a secret compromise might net them better results (i.e. an agreement to gain the Arab portions) than to compete with larger Arab neighbors, such as Egypt or Syria. This was compounded in importance by the fact that Egypt and Jordan were rivals in the lead-up to the conflict, and approached it from different perspectives. Jordan, advised by the Arab Legion's head (a British commander named John Bagot Glubb), believed that the Arab forces were naive to think they could defeat the Jewish forces, and Abdullah was most conscious of this, saying that, \"The Jews are too strong -- it is a mistake to make war\". While other Arab leaders doubted victory, their inept military commands and the Arab League's closest thing to a plan seemed to approach conflict with overly optimistic ideas. As Glubb put it, the war pitch led to a situation where \"Doubters were denounced as traitors\", but only Jordan appeared to be as clearly aware of just how poor the planning/capability was and therefore willing to seek escape from the strictures of war.\n\nBesides the question of gross resources, competition between Arab states, and awareness of military discrepancies, there existed yet another reason why Jordan and Israel often found themselves drifting together. This reason lay primarily in the shifting demographics of Jordan following the 1948 war. The influx of Palestinian refugees from this war into the West Bank and Jordan, and Jordan's desire to solidify its control over the West Bank, meant Jordan had an inherently aligned strategic interest in integrating Palestinian refugees with Israel's desire to see those refugees integrated (to avoid claims for return to Israel in the long-run, a situation that has persisted to present-day). At the same time, Jordan sought integration in a way to attempt to reduce Palestinian nationalism, and to buffer his own claim to the West Bank, a claim that the Arab world largely never recognized (but that Israel, in 1947, was semi-willing to accept in exchange for peace). While this proposal never included Jerusalem of course, the common ground there was far greater than the common ground with Egypt or Syria, who treated Palestinian refugees quite differently and had gained little territory as a result of the 1948 war (and the land they did gain was of questionable value, compared to the Jordanian gains of coveted Jerusalem and arable land). In fact, it is even arguable that as Jordan had gained most of what it wanted, its remaining conflict with Israel was more related to the question of Arab unity (until 1967, of course) than it was to specific claims it wished to make to Israeli territory. Jordan, rationally, feared Palestinian reactions if it sought to overtly accept Israel's existence (amplified by the assassination of King Abdullah in 1951 predicated on this fear), but it also feared Palestinian reactions if it sought too strongly to erase Palestinian nationalism without care. As a result, Jordan's balancing act largely failed: Palestinians never came to view themselves as true Jordanians, were excluded from Arab Legion combat formations, and were barred from high-ranking positions in the civil bureaucracy, for fear of potential coup (particularly since Palestinians made up such a large proportion of the population). Egypt and Syria, on the other hand, remained largely low on gains from 1948, still coveted and fought with Israel over things like water and passageways (such as the diversions of water from the Sea of Galilee/Jordan River, or conflict over the Gulf of Aqaba). Furthermore, Egypt sought (particularly under Nasser) a role of regional hegemony, and opposition to Israel and the West were a crucial component of Nasser's strategy in mass appeal. His ability to gain influence in other countries was also a source of great concern to Jordan, Israel, and the West, which led them to covertly remain more friendly than they otherwise might have. Nasser's rise thereby made friends out of those who had previously fought, and who had also had less disagreement prior themselves." ] }

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{ "a_id": [ "e8buj81" ], "score": [ 2 ], "text": [ "If the economy dips less people are buying things, if less people are buying things then companies that make things can't afford to hire so many people to make those things. Those people lose their jobs and have less resources to buy things, and so on, and so on. \n\nHouses are lost because the bank expects you to pay mortgages, cars are repossessed, utilities are shut off.\n\nQuality of life goes down. \n\nMore people die from disease that could have been treated if they could afford it. \n\nCrime rate goes up. " ] }

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{ "a_id": [ "ffpgz0a", "ffphamy", "ffpiofa", "ffpjjpq", "ffpo88v", "ffpzltg", "ffqjb0u" ], "score": [ 3, 3, 36, 4, 9, 2, 3 ], "text": [ "When a helicopters engine fails they become big metal bricks. A plane however, the shape allows for some control and the ability to glide while trying to get the engines back to working. Most planes have multiple engines as well, if one fails the others compensate. There’s no such redundancy in helicopters.", "Depends on if they are single or dual engine. \n\nI’d say more often than not though it’s pilots that are flying in weather they should not be flying in", "Helicopters have extremely poor glide characteristics. Your best case scenario for a malfunction resulting in loss of lift is a controlled crash. There are a lot of flight regimes in which you're basically just 100% screwed in a helicopter because you simply don't have enough velocity or altitude to make any real recovery.\n\nPlanes have a lot more options because they are much simpler machines, and most are pretty decent gliders. A small private plane that loses power at altitude can get a pretty good distance before he hits the ground. That allows for the pilot to have some time to consider the situation, attempt to recover the aircraft, or pick a good spot to land/crash.\n\nHelicopters also tend to operate near the ground a lot more often than planes.", "Helicopters can land safely even when the engine fails. It's called \"autorotation\".\n\nThe pilot lowers the \"collective\" lever - the one which makes the helicopter go up and down. This results in the angle of the rotor blades changing, so that as the helicopter descends, the airflow through the rotor causes the rotor to rotate (and therefore giving the pilot control), and causing drag (slowing the helicopter down).\n\nHelicopters don't have much control when the engine fails, but because they can land almost anywhere, this is all the control they need - enough to pick somewhere directly below and land.\n\nMost larger helicopters have two engines, though, so an engine failure is much less of an issue.", "Your premise itself is incorrect. Helicopters crash less than fix winged aircraft. [Here](_URL_0_) is the relevant data from 2014. It is just that there have been several high profile celebrity deaths from helicopter crashes, which makes people think they are more common.", "Well they don't crash very often. But as with most aviation incidents, especially fatal ones, the incidents are given a tremendous amount of media coverage. Car accidents are tremendously common, involving roughly 1 million crashes per year just in America, with about 30,000 deaths, but because of how common they are we barely hear about them. But an airliner crash is primetime news, often for days or week", "The people saying helicopters are less stable or inherently less safe than fixed-wing aircraft (planes) are mistaken. Autorotation (described by /u/jacklychi) allows helicopters to make controlled landings without an engine very easily, and helicopters get just as many safety inspections as any other aircraft, more or less, *if* they are for commercial transportation.\n\nThe biggest difference is that helicopters are used primarily for low, short flights between nearby destinations. Autorotation requires a certain height above the ground in order to work - that means if a helicopter loses and engine it's safer if you're *higher* up. Except that most helicopters are flying lower to the ground. That makes autorotation more difficult. And since helicopters are usually flying over populated areas it's less likely that a helicopter will be able to find a clear, open place to land. Although autorotation allows a helicopter to land safely if it has a place to land, they still don't have glide slopes - you're not going to get very far, only straight down. A plane will be flying probably much higher and although a landing without an engine is more dangerous, they will at least have more energy and lift to travel horizontally to a safer, emptier place.\n\nThe tendency for helicopters to be used for lower, shorter flights also puts them closer to obstacles like power lines, buildings, birds, and even tall trees. In the case of the Kobe crash, it crashed into a hillside. Visibility was poor. Although the cause has not yet been determined, it *could* be as simple as the pilot misread the instruments and didn't see the hillside until it was too late to avoid it. Compare that to most passenger planes which would be flying so high that not being able to see the terrain isn't an issue, because there isn't any. I have zero other information, I'm not saying that was the cause, I am only suggesting that it *could* be a cause which is generally not true of most commercial passenger flights.\n\nThe other problem is that helicopters are more likely to be privately owned and operated, at least compared to big passenger planes. Those are regulated *very* strictly. Although *any* flights are very regulated, a small for-hire helicopter service may not have the same stringency applied to it as other modes of air travel. This is also true of small planes, too, and one of the reasons they tend to crash more often than big passenger planes." ] }

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{ "a_id": [ "cscswjf" ], "score": [ 2 ], "text": [ "A derivative is a contract you can buy and sell. For example, \"whoever holds this piece of paper can buy 100 shares of IBM from me for $50 per share.\" Now, if IBM is worth a lot more than $50 a share, that piece of paper is valuable and you can sell it -- someone will pay good money for it, and its value fluctuates as IBM's (present and future) value fluctuate.\n\nAn option is a specific kind of derivative -- one which says you have the right to buy (or sell) a certain thing at a certain price if you want, often with a certain time constraint. The above example is an option. \n\nThere are also more complex derivatives, such as \"I agree to deliver you any combination of apples and oranges totaling 100,000 kg, at a time of my choosing in November 2016, for a price equal to the then-current price of 1000 barrels of Brent crude oil, but only if the USA has exited Iraq by that time.\"" ] }

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{ "a_id": [ "c972uqb" ], "score": [ 3 ], "text": [ "Start by reading [this](_URL_0_) to learn about the functions of bone, which go beyond the structural." ] }

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[ [ "http://en.wikipedia.org/wiki/Bone#Functions" ] ]