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1aw5h2 | What's stopping a black hole from growing exponentially massive and destroying entire systems? | I have a pretty tenuous grasp on how black holes exist, but I just watched _URL_0_ this video about black holes colliding. They said that it would make a bigger black hole.
So my question is: what would happen if there was just a giant black hole that's gravitational pull grew over time to be so massive that it altered entire solar systems and destroying galaxies? | askscience | http://www.reddit.com/r/askscience/comments/1aw5h2/whats_stopping_a_black_hole_from_growing/ | {
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"You might be interested in reading about [Sagittarius A*](_URL_0_), which is likely a colossal black hole at the center of our galaxy. It's thought to be about 12 light hours across, or about the size of the orbit of Neptune, and have a mass of about 5 million stars. \n\nIn fact, it's now commonly believe that every spiral galaxy has a super-massive black hole at it's core. The only thing really keeping them from destroying everything is... time. It take a long time to destroy a galaxy, much less the universe, as evidence by our survival for the last 13.2 billion years or so. \n\nIn reality, the orbits of star systems around the galactic center are very stable, and it will take enormous amounts of time for them to decay to the point of being consumed by a black hole. Just like our planets have orbited relatively stably for billions of years, so does the sun. ",
"You might consider the fact that although the Sun is vastly more massive than anything else in the solar system, the planets don't fall into the Sun. Basically, the centrifugal force a planet's orbit around the Sun prevents it from falling inward.\n\nNow, a planet could fall into the Sun if it hit another planet head-on and they both lost all their orbital momentum, so that there wasn't any centrifugal force keeping them from falling in. This sort of thing can and does happen near black holes, so they can grow. But it's not a simple process of \"the black hole has a big gravitational field which sucks in everything nearby.\" You can orbit a black hole and be perfectly safe until you lose your orbital momentum to a collision.\n\nFurthermore, suppose the entire interior of the galaxy collapsed into a black hole. It wouldn't really affect us much. We already feel the gravity of the entire interior of the galaxy, and its gravitational pull won't increase just because it's concentrated into one black hole. The solar system would continue on its orbit around the galactic center more or less unaffected--unless, perhaps we had an encounter with another start system that robbed us of our orbital momentum around the galactic center. Then we would plunge in.\n\nThe point is, black holes don't grow as quickly as you might think.",
"Gravity doesn't suck things in. Most objects are moving at a great speed and thus they orbit other things. A black hole has no special power to suck things in, it's just a lot bigger than many stellar objects. They don't get big enough to destroy galaxies.\n\n_URL_0_\n\nThe event horizon of a black hole with a mass of ten times our galaxy would have a radius of 0.5% of a light year. That's not even close to galaxy destroying."
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y7395 | When they say that CERN achieved a heat record of ~5 trillion degrees, what does that actually mean/do? | What are the actual real-world observable effects of that heat? Is it in a really, really small space? How do they know how hot it gets? Even if it is in a really small space, does the extremity of the heat cause the overall chamber temperature or the surroundings to warm noticeably?
EDIT: Today I was reminded that heat and temperature are not the same thing. Unfortunately, I cannot amend the title of the post to reflect that. But it should say temperature, not heat.
(referring to [this post](_URL_0_)) | askscience | http://www.reddit.com/r/askscience/comments/y7395/when_they_say_that_cern_achieved_a_heat_record_of/ | {
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"It is a really, really small space with very, very few particles in it. So the real world effect is incredibly, undetectably small. The temperature is measured by looking at the energy of released particles, or by the spectrum of emitted thermal photons. That's why the article says they have to convert the energy measurement to a temperature.\n\nInteresting follow up I don't know the answer to - can you then assign a temperature to the p-p collisions at the LHC? I would think those have an even higher average energy, and thus higher temperature.",
"Physicists often use \"temperature\" as a way of describing the average kinetic energy of a group of particles. The total energy involved is small, but the energy per particle is large, thus the temperature is large. \n\n See [Wikipedia on the temperature of gasses](_URL_0_) for a somewhat relevant discussion.",
"And, how the heck do they measure that? Wouldn't a thermometer melt?",
"_URL_0_\nIt's all a trick of chart conversions. Temperature is a measure of the kinetic energy of a particle(s). We have a system for converting wave and mass particle energies into temperature. \n\nThey are inducing stupidly high amounts of momentum into particles so when they collide they produce detectable energies that give silly temperature numbers when converted. \n\nNo physicist should use temperature as a measure of a system outside of basic chemical reactions. They do it because it makes sensational titles. To put this is perspective, that 5 trillion degree detection could go off next to your head and you wouldn't even know it.",
"Think about a spark given off from a circular saw on steel, try to estimate its temperature. Now estimate the temperature of boiling water in a kettle. Which is higher? Now, which would you rather have be dropped on you? Why?\n\nThere's an important difference between 'thermal energy' and 'temperature.' Heat is the transfer of thermal energy.\n\nThermal energy is the energy stored in a system, whereas temperature is the average energy of a single particle in the system.\n\nThere's a property called Specific Heat Capacity (usually denoted C). Essentially, the higher the C value is, the more heat energy has to be pumped into a substance in order to raise its temperature. Water has a very high specific heat capacity, which is why it takes a long time to boil water (and a lot of electricity), and also why it is used in industrial cooling - because it takes a lot of energy out of a system without getting hot too easily, acting as a buffer.",
"Can someone explain to me how CERN can make particles that hot without melting the machine itself?",
"Dumb question... but how do they determine the temperature? Because to a simple guy like me a trillion degrees is really hot",
"What is the practical application of being able to do this? And is there a way to convert this to energy? "
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3tmerk | Can you give any information about this flag? | _URL_0_
There are photos and what information we have gathered in the link. Anything further would be much appreciated, as we are having a hard time finding anything out about it. Thank you for your time. | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/3tmerk/can_you_give_any_information_about_this_flag/ | {
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"hi! Do consider x-posting this to /r/vexillology (the flag sub!)"
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35f0qm | why do we grow out of things. | Why do humans grow out of kids shows, toys, etc. theres no real "force" demanding us to
People view it as immature but what makes them think its immature | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/35f0qm/eli5_why_do_we_grow_out_of_things/ | {
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"Because your tastes change as you get older and you learn more about the world and develop your social life. As you're exposed to more, better media, you start to realize how underdeveloped, uninteresting, and pandering a lot of children's media is. "
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59pxe6 | What property decides if a material can be a superconductor? | askscience | https://www.reddit.com/r/askscience/comments/59pxe6/what_property_decides_if_a_material_can_be_a/ | {
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"That is a really hard question to answer, mainly because there's several classes of superconductors and only for one of those we really understand all the details.\n**Conventional** superconductors can be explained by [BCS Theory](_URL_0_). The gist of this theory is that 2 electrons interact with each other via deformations/vibrations of the atomic lattice in the material. In this case they are no longer 2 independent electrons but can instead be thought of as a \"Cooper pair\". This cooper pair now has very different behavior compared to simple electrons (the details of why this is the case needs too much background information to just explain in this short answer) and can travel through the material without any resistance.\n\nWith that explanation of superconductivity it's perhaps easy to see that, to become superconducting, materials need a strong interaction between the electrons and the atomic lattice vibrations. The stronger the electrons interact with the lattice, the easier they can \"use\" those interactions to \"talk to each other\".\n\nThis also explains why you need low temperatures for superconductivity. The temperature of the material is nothing other than the lattice vibrations, so if you have too high a temperature, the lattice deformations of the electrons just get drowned out in all the thermal lattice vibrations happening.\n\n\n\nThis is only true for the conventional superconductors though. There are high temperature superconductors like YBCO (Yttrium Barium Copper Oxide) and other cuprates where the mechanism of superconductivity is still mostly unclear. There are 2 main theories about this unconventional superconductivity, one supposes that you can explain it by a coupling between layers of conventional superconductors that boosts the transition temperature to higher values and the other theory explains these materials by antiferromagnetic spin fluctuations. Explaining the latter one is really beyond the scope of this answer and since I don't do research on high-temperature superconductors I'm not really the right person to answer that anyway."
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1njwn9 | my company has a wifi network for their employees to connect their "personal devices" to. can they see everything i do? | I understand that they can see all of the "http" traffic, and at least the internet address of the "https" places I go. But when I connect to the network, I have to enter my user name, password, and accept a certificate, which turns on my big brother alert! Can they even snoop in on my secure connections? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1njwn9/eli5_my_company_has_a_wifi_network_for_their/ | {
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"Do you log in by joining the network, then every time you try to go to a webpage it redirects you to a login form? Because if that's the case the certificate warning is probably just that the browser thinks your connection has been hijacked because it knows that Google (Assuming that's your home page) doesn't use the certificate that the login page does.\n\nTo be fair to your browser your connection **was** hijacked, but it's not malicious, just annoying and stupid for failing to use a proper login system. You can ignore it then.",
"Connections that are end-to-end encrypted should be secure, assuming that your company isn't doing some sort of man-in-the-middle attack on your traffic.\n\n\"Man in the middle\" would be that you try to get a secure connection to Site A, and a machine on the company network replies saying that it is Site A, and then you send all your encrypted data to that machine. Then it forwards the messages on to the actual Site A, but only after decrypting it and saving a copy somewhere.\n"
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3sj1pj | why aren't women allowed in the royal armoured corps? | The British Army's site says:
> Women are able to apply for most jobs in the Army. The only ones currently not open to women are the Household Cavalry, Royal Armoured Corps and Infantry.
How come? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/3sj1pj/eli5_why_arent_women_allowed_in_the_royal/ | {
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"They *can* join the Household Cavalry, Armoured Corps and Infantry regiments, they are just not allowed an active combat role.\n\nI don't want to get into a debate about the reasons (can't be bothered to do this again) but remember that when people start to compare the physical fitness don't make the mistake of thinking Ronda Rousey vs Maurice Moss (without the gun) but think Ronda Rousey Vs Mike Tyson in his prime. I.E. people will start to compare well known physically fit women against the average guy on the street, not to well known physically fit men. "
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6rl0i7 | what gives soap operas that “low quality” feeling to them? is it the lighting? the dialogue? it’s very distinct, but hard to pin down. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/6rl0i7/eli5_what_gives_soap_operas_that_low_quality/ | {
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"It's the frame rate. Most soap operas are shot at 30 frames per second (technically 29.976 but that's irrelevant). Film is shot at 24fps. We have been trained by experience to see higher frame rate video as being lower quality.",
"It's called [Motion Interpolation](_URL_0_) or the \"Soap Opera Effect\" ",
"It's a combination of all of the above, but I'd say that lighting is the most important.\n\nNormally, when a movie or higher-quality television show is filmed, each shot is individually lit. For example, for a dialog between two people, they would set up one camera pointing at one person and light the scene for that camera's benefit. Then, they'd switch it all around to point at the other person and shoot the scene again. Then they edit the two takes together to get one where the point of view changes.\n\nWith a soap opera or something else that has to be filmed quickly and/or on a budget, they set up two cameras and do the whole scene in one take. This means that the lighting has to be set up in a more bland way to accommodate two cameras at once.",
"I've tried to figure it out too, and the best I can come up with is this:\n\n1) Everything is filmed on a soundstage. There are no outside shots, no city streets, not even any greenscreening. It's all very clearly done on a series of indoor sets. Fake cars, fake trees, no indications of what buildings look like from the outside. This above anything else makes a soap opera feel like some kind of community theatre play.\n\n2) No sound effects. Outside the occasional gunshot or screeching tires, the only sounds are the sappy music and the dialogue. ",
"The cinematography is also very rigid compared to movies IMO. Camera movement is minimal. ",
"It is the lack of time to set up every scene. They are very rushed to get content out. Everything gets slammed together, from writing, to lighting, to number of takes, etc. A lot of crap makes it the screen that might be reshot or killed in editing because of the time pressure.",
"Most of the effect is due to the higher frame rate of 30 or sometime 48 or even 60 fps. As modern humans our brains have been trained to recognize the 24fps (ok fine 23.976 and don't even get me started on NTSC and PAL...) as \"cinematic\" and 30fps as \"live\". \n\n To use an example: Saturday night live vs. the SNl digital shorts. SNL proper has the \"live\" look and the shorts have the \"cinema\" quality to them.\n\n",
"Apart from lighting/frame rate, if you watch closely, on almost every camera switch in a soap opera they slowly zoom in until the next camera switch.\n\nOnce you notice it the effect is maddening.",
"What ive noticed is that american soap operas have that \"low quality\" feeling but mexican soap operas (Novelas) are just so well made for the same story every year ",
"You can actually reproduce the FPS changing how a movie feels on a computer very easily.\n\nThere's a smooth video project out there that will add frames via interpolation. For action movies it sort of sucks. A lot of weird artifacts, but go watch something like game of thrones at 59.97 fps and 23.xx fps. You know it's game of thrones. But... different ",
"Omiglob - I have been thinking the SAME THING since childhood!!! Thank-you for asking this question!!!!! ",
"This doesn't answer your question, but there is a setting on newer tv's that make everything look like a soap opera. I noticed when I was at my cousins house and watching The Godfather, and I'm like why does it look like a goddamn soap opera and who would want that? So, umm, what is that setting and how does it work?",
"Here are a couple that I always notice:\n\n1. ) Audio quality. It makes a big difference to have someone's vocal audio sequestered from any foley that occurs in a scene, such as door closes, foot steps, clothing. Everything is normalized together, in the same input mic, so you hear EVERYTHING on the sound stage, including the echoes of every sound in the scene. It may appear that they're walking around in a tuscan villa, but it SOUNDS like they're walking on particle board with no insulation.\n\n2. ) Framerate. Not sure why they do this, but they run at 30 or 60 fps, yet snap to 24 FPS when they step outside. This inconsistency is jarring. A higher framerate doesn't make it bad, but it sets it apart from traditional cinematic features that run at 24 FPS.\n\n3. ) Everything is formulaic. Everything. You watch a soap opera from today, and put it next to a soap opera from 30 years ago, and you won't find much difference. Probably just the hair and fashion. LOL! The camera angles, the lighting, the music, and the plot lines are all the same. Scene opens. Music intro. Enter Actor A and Actor B. Actor A's body language clearly shows that they like/dislike Actor B. Camera films Actor A talking to Actor B. Camera films Actor B's reaction, and holds for a music stab on dramatic scene conclusion. It's amazing what simple things like establishing shots, higher/lower/closer/skewed/contextual camera shots do to a scene to make it more visually interesting, and how it changes the context of the dialog.\n\n4. ) There is no real story, no overarching character plot or development. You're essentially watching dramatic improv revolving around the personal lives of a collective group of individuals in a single location. The show is about how Actor A wrongs Actor B, and how it gets resolved by Actor B retaliating against Actor A, which somehow affects a third party, Actor C. Now, Actor B has done the wronging, Actor C retaliates, and Actor A is somehow wronged. Rinse and repeat. Add as many actors as you like to keep it varied, and maybe broaden the audience's demographic by letting more people connect with more actors with different identitarian traits (gender, race, culture, creed, age, etc...). It's gossip personified, which some people are absolutely fine with wasting their time on, but most of us aren't. \n\n",
"Higher frame rate lets you see more details in every second of footage. So you will notice things that are fake easier, like when the hobbit was shot at 48 fps, people complained it looked worse because it was a lot easier to tell it was people in costumes rather than actual dwarfs.\n\n\n\nSame goes for resolution, more pixels, easier to see details like tape holding the backdrop in place, or glue holding someone's wig on.",
"It always amazed me how long a conversation takes in soap operas. \n\"Did you know Joe is missing?\" \n10 seconds passes\n\"I don't know Joe.\"\n15 seconds of staring at each other. \n\"Is he dead?!?!\" \n25 seconds of staring \nDun dun duuuuuuuuuuuuh! ",
"Budget and time. The biggest reason is probably that they are shot on video instead of film. This is cheaper and allows them to get the project turned around much faster than film. Also, the lighting is much different, due in part to being video, and partly to backlighting being a more exopesinve option.",
"It's the image, and there are several parts to it; like some people have mentioned, the lighting tends to be very functional; the cameras are also often cheaper, (though even cheap cameras are excellent these days). As far as I know though, frame-rate has very little to do with it - though high frame-rates can give stuff a \"hyper-realistic\" look, that's not what's going on with soaps. I have no idea why people keep saying it's frame-rates, I mean there's a standard of 25 for PAL or 30 in the US, corresponding to 50Hz and 60Hz, and while you can get some cool effects these days by shooting at multiples of these, it's not like soaps looking cheap is a new phenomenon. \n\n*EDIT: Looking at some of the other answers, there may be something to this theory when it comes to modern soaps, on modern TVs - \"the Hobbit effect\". However, like I said, it's not a new phenomenon, so it's still just a piece of the puzzle.*\n\nMore than anything, there's a lack of serious color correction in post; like I said, most cameras today are actually very good, but just look at your own camera phone - a normal still shot can look terrible, and sometimes kind of \"flat\", but add a cool filter, and suddenly it looks almost professional. Same with \"home videos\" - even with a great camera, they often have this... soap-y look - but give me enough time with some good digital tools, and I (actually, my editor) will make your vacation video look like it was shot by Hoyte van Hoytema. For movies and TV, color correctors will spend ages making sure every single frame has *juuuuusst* the right look, and correcting any lighting/color errors (and this is where an expensive camera shines, often having more information in each frame, allowing for more correction) . For soap operas, not so much - you just go by the scene lighting, perhaps sometimes putting a general filter on a whole scene if something is actually offensively horrible.\n\n***However, all these are just symptoms of the real reason*** - soap operas are designed to be aired 4-5 nights a week, almost year-round. They are produced incredibly cheaply, at an incredible rate; some are shot \"as-live\", with almost no retakes (typically 60 minutes shot for 30 minutes on-air), and edited overnight. It's not that the people working with them are incompetent (often quite the opposite), it's just... there's no time. So it's original lighting, barely any color-correction, little to no retakes, and speedspeedspeed.\n\nSource: am TV Producer.\n\ntl;dr All the \"reasons\" are just symptoms of the fact that soaps are produced at an incredible rate, for almost no money. \n",
"I think it is because the soap opera seems like a stage performance. The charm (for lack of better word) of soap operas is that they make you feel like you aren't watching a real life scene. It's more like you're sitting in on a theater performance. \n\nThis same feeling is the feeling I get with all the new shows on 4k televisions. They seem so real that the setting seems staged now. I'm watching House of Cards these days and I feel like I'm watching a stage performance, when before it felt like I was a fly on the wall in the Oval Office. When you can see every single prop (coffee mugs, folded newspapers etc) you realize that this was intentionally placed by someone and it bothers me now.\n\nBut back to soap operas. Soaps have little time to get settings right so they seem natural since they are recording every day almost. ",
"Let's compile a small list. I'm a film student and a radio television major so there's actually a lot of answers but in my opinion the biggest one is the first.\n\n1. Frame rate: Try looking up the hobbit shot at 60fps. It looks like a sitcom! There's also TVs that \"smooth\" between frames which make shows like Lost look like.. a sitcom. We associate the film standard, 24fps, with drama, fiction, etc. We associate 30-60 with documentaries, sitcoms, even low budget stuff!\n\n2. Lighting: it's cheaper, faster, simpler, to just stick some lights that light up everything on the set. These set ups are usually shot on a soundstage, with rows of lights overhead making it even easier. There's nothing dramatic about flat lighting and nothing super exciting.\n\n3. Dialogue: This one might surprise you! Some soap operas are on such a tight schedule the actors might read their lines from strategically placed cards around the set. We were shown an example in one of my classes (can't remember it right now) but someone who had been shot was on the ground very obviously looking at something and then looking back at their eyeline to deliver the lines he just read.\n\n4. Laugh tracks: This ones easy. Would the characters be pausing if there wasn't a laugh track?\n\n5. The rest: it can then boil down to production quality, acting, editing (sometimes done on set, while filming with a switcher) music and whatever. The lower the budget and tighter the schedule can make for some cheesy moments!",
"It took me forever to realize why I got the same feeling from sit-coms. For me, it's the characters' interactions with each other. They seem forced... why are they always standing so close to each other in the kitchen? In better shows, one will always be sitting at the table or looking through the fridge (only to be disappointed there's nothing they want) like normal people.",
"It’s because they need to shoot one or more episodes a day. They don’t have time to polish it. They use nearly all the footage they shoot and rarely have time for multiples takes, unless something goes terribly wrong. This is increasingly made difficult when they have to shoot scenes outside without the controls offered by a studio environment where weather and lighting is often unpredictable, meaning they will someone shoot a scene that will be aired in two days time and ten minutes later shoot a scene that will be aired 3 weeks away just to make tha most of favourable conditions. That footage then has to be catalogued and edited. It’s a very quick turnaround with soaps. ",
"Last summer I spent a week binging on Passions and I realized that I couldn't finish because it's the same rinse and repeat method. The 24 hour wait as well as the weekends really make it seem a bit more suspenseful.",
"A lot of people here are talking about lighting and sound. As someone who worked in television I can tell you it's probably due to the fact they don't have time to put it through proper post processing. No lighting or color correcting, no Additional Dialog Recording or ADR.\n\nIf you watch some deleted scenes that were unfinished in movies you can get a real soap opera feel to them.\n\n[Here is a link to an example from an old reddit post](_URL_0_)",
"The only soaps I've ever watched are either English (Coronation Street) and a few Mexican ones (because they're better than the nonexistent Spanish ones), and I've never really noticed any of that tbh."
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219td1 | Is there a drug linked to brain growth and development similar to how testosterone and FSH are linked to muscle growth and developent? | I've been perusing the web for a few days now looking into any current studies on increasing intelligence and brain development. The results I've found are quite far and few so I'm asking /r/askscience if they've stumbled across anything in their web searches or had personal experience with any of these studies or topics related.
Essentially I'm curious if there have been any drugs/hormones/signaling active molecules linked to brain growth analgous to that of testosterone and FSH being linked to muscle groth and development. | askscience | http://www.reddit.com/r/askscience/comments/219td1/is_there_a_drug_linked_to_brain_growth_and/ | {
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"I'll edit this post to include some more hard science later, but check out /r/Nootropics \n\nNootropics are 'cognitive enhancing drugs', and may increase \"intelligence\"."
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|
44xsd2 | Manichaeism seems almost unique in being a former major international world religion that was rendered completely extinct without even small remnant populations. Why did it disappear so entirely? | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/44xsd2/manichaeism_seems_almost_unique_in_being_a_former/ | {
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"What is a world religion? Roman paganism had millions of adherents, reduced to nothing. Ditto for the so-called mystery religions (besides possibly Christianity) that sprung out of: the cult of Isis, Mithraism, etc. Egyptian religion similarly had millions of adherents and died away. Aztec religion. Name a pre-Christian or Muslim society that had millions of people and, for the most part, the religions they once practiced are gone (the other major proselytizing contemporary religion, Buddhism, was less likely to annihilate pre-contact customs, though did it as well, depending on how you quite deal with religious mixing). \n\nMore importantly, you have Zoroastrianism, which survived on to the present day only with likely only a few hundred thousand people. \n\nNow, this doesn't fully explain which religions survive and which die, but generally, even before the ~~Treaty of Westphalia~~ Peace of Augsburg which coined the term, *cuius regio eius religio*, that is, he who rules, his religion. The Roman Empire, generally, tolerated a wide variety of cults and religions so long as their adherents remained subservient to the Emperor and partook the imperial cult in addition to whatever other practices they subscribed to.\n\nChristianity was very different, and generally only allowed Judaism in its territory until after the Enlightenment. Islam similarly only allowed Christianity, Judaism, and Zoroastrianism. \n\nWithout either official support or a special recognized legal status and a loyal, ethnicized community, most religions falter. Manichaneanism reached China, for example, but like the early [Christian](_URL_3_) and [Jewish](_URL_1_) communities of China, which essentially disappeared (there is a small remnant which claims descent from the Jewish community in Kaifeng, but the community seems to have been permanently disrupted in the 19th century). The indigenous [ethnic Chinese Muslim community](_URL_0_) thrived, its survival likely due in part to the fact that it didn't end up isolated like the Jews and Christians. Religious communities can survive surprisingly long periods of isolation and persecution (see, for example, the Japanese [Kirishitans](_URL_2_)), but not forever. The Kaifeng Jews (Jews, with their strict bans on intermarriage, strong international ties, distinct identity, written tradition, and dietary laws the prevented too much socialization across community lines, have tended to have faired better in diaspora and out of power than most groups) are a good example: even by the 16th century when Jesuit missionary Matteo Ricci is in contact with them, they complain that their isolation has left them with a lack of learning. We have Manichean documents going at least into the 11th and 12th centuries. Not bad for a millennium out of power as a universalist religion (another difference from the Jews, whose claims of spiritual chosenness were not as harmed by their obvious small numbers). "
]
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"https://en.wikipedia.org/wiki/Kirishitan",
"https://en.wikipedia.org/wiki/Church_of_the_East_in_China"
]
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||
7rfyig | can every single thing a computer does be broken down into binary code? | When I say every single thing, I am talking about what's displayed on the monitor. Obviously the electronic signals arent in binary. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/7rfyig/eli5_can_every_single_thing_a_computer_does_be/ | {
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"...the signals going to the monitor are in binary. Once inside the monitor, the signals get reinterpreted by the controller ciruits, in binary and determine the brightness of each color pixel, whose data is in binary. The pixels themselves are sent binary signals. The brightness of the pixel is controlled by how long the pixel is pulsed at ON state vs OFF state. ",
"Yes. The computer only knows anything as ones and zeroes. Doesn't matter what it is. There is a very complicated process stuff goes through to be displayed as what you see, but it is all stored as binary and interpreted as binary when the computer does any operation on any data. Even the operations the computer does are stored as ones and zeroes. Code is broken down from the high level languages like C#/C++/C and Java and Python, into assembly instructions which are a series of simple statements like Add, Subtract, Move Data between two locations, skip to a specific instruction, etc. Each assembly instruction has a specific sequence of bits that denotes it so the CPU knows what operation to perform.\n\nAs such, there are hundreds of conventions set up as to how data/code is stored so a computer knows how to interpret it. I can try to give some examples but it might be difficult to understand or else pretty lengthy.",
"At the core of everything, a computer *computes*. This means that *everything it does* involves working with numbers. If you remember this, you can ignore \"binary code\" - that's just another way of storing numbers. If you add five and five together, you are always getting ten; even if you have to spell that as \"101 + 101 = 1010\", the math doesn't change.\n\nBinary is used **because** it's really easy to transmit as an electrical signal. All you need is two voltages (e.g. 0V and +3V) to move those numbers along unambiguously.",
"Desktop computers are all binary. They work only in the realm of base2 numbers, IE 1's and 0's. Anything they do that is analog, IE not 1's and 0's is converted from 1's and 0's to analog wave forms by DAC's, but internally to the computer it is purely a digital information. \n\ncomputers do have higher levels of organization which can be broken up into base 8 numbers or hexadecimal, but those are ultimately decoded back into bytes and bits of 1's and 0's. \n\nBefore HDMI, DVI, and Display port, video monitors were analog using VGA connectors which sent sync, red, green, and blue analog signals. The video card has a DAC which converts the digital equivalents for the image, into analog signals that the monitor can understand. \n\nModern displays though are digital. The display and color information is sent purely as a bitstream of 1's and 0's, converted by the monitor into a matrix of pixels, and the LCD drivers convert those values into electrical signals that rapidly cycle off and on, to get the different colors, and brightness of pixels. \n\nThere are 2 main exceptions to this though. Analog computers were some of the first computers in use before digital computers became prevalent. They didn't operate using binary digits, but instead used analog voltages. Instead of digital logic gates like AND, NAND, OR, NOR, they used a series of connected motors and rotary encoders to twist knobs and have the results of those value twist other knobs, to perform calculations. Think of it like a feedback loop where a small difference is amplified physically by the motion of groups of servos. Some of the Vietnam era flight simulators used by the Air Force, were based on analog servo computers. \n\nThe other one is quantum computers, which use Q-bits instead of binary bits. They are capable of storing values other than just 1's and 0's. "
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1c7gxo | How did Britain keep the value of its currency stable during its explosive growth in the 19th Century? [reposted because unanswered] | I ask while reading Arrighi's Long 20th Century. How is it possible that Britain maintained a stable pegged currency while so much capital flowed into the country? Was it just the growth in supply of gold? | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/1c7gxo/how_did_britain_keep_the_value_of_its_currency/ | {
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" > Was it just the growth in supply of gold?\n\nThat was a big part of it. You had gold strikes in California, the Yukon, South Africa, Colorado, Australia, and so on, all increasing the money supply.\n\nAnother big part was the growth in the private creation of paper money by [commercial banks](_URL_0_), as well as by the circulation of bills of exchange (essentially checks that were endorsed from hand to hand, sometimes dozens of times, sometimes crossing oceans, so a little bit of \"real\" money created a lot of paper money). \n\nYou also had periodic crashes when, essentially, the money supply would run out; the decision to maintain a gold standard was by no means without casualties. \n\nSo the British (and most of the rest of the world) maintained the value of their currency in part simply because they decided to--they chose enduring brutal depressions on a regular basis rather than printing money when it was needed."
]
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"http://en.wikipedia.org/wiki/Fractional_reserve_banking"
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cev5k2 | how do treadmills and other machines track your hearts bpm by those silver things on the handle? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/cev5k2/eli5_how_do_treadmills_and_other_machines_track/ | {
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"The basic concept to be aware of here is what makes the heart beat.\n\nOur heartbeat is driven by an electrical signal generated by a small group of cells (sometimes called pacemaker cells) located within our heart. The electric pulse generated by this group spreads through the heart, causing first one part, then the other to contract and relax. (As an aside, this is why electric shocks are so dangerous; they disrupt that group of cells and stop our hearts from effectively beating.)\n\n***However***, this pulse isn't confined to the heart; it spreads through the body, because our insides conduct electricity rather well. So, we constantly have an electrical pulse in our body as well.\n\nWhen we touch the silvery section of an exercise machine, the circuitry inside the machine can actually detect those minute changes in voltage caused by the pacemaker cells in our heart; from there, it can do some fancy math to separate one beat from the next, and arrive at an estimation of your heart rate.",
"The silver things on the handle are electrodes. Think like those little pads that you see taped on a patient in movies and TV that give the hospital a patient's vital signs. those pads run a low level current (being sweaty makes them contact better, which helps get the reading, too) that checks the resistance of your skin.\n\nWhen you have a heart beat, it causes the blood vessels in your hands to expand and contract. This causes the resistance between those two pads to change a little bit, and the machine is able to track those changes and count them as heartbeats.\n\nIt's worth noting that yes, there's a lot that can throw those readings off, and yes, they aren't always reliable- you wouldn't use them for something important like a life or death situation, but they are close enough for exercising to."
]
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q3j1g | why is it illegal to not hire somebody because of their race/religion? | Before you lose your crap and call me a racist, don't. I wouldn't not hire somebody because of their race or religion, but I don't understand why somebody who doesn't want a certain person to work their **has** to hire them against their will. It is their business, shouldn't they be allowed to hire whomever they want? Besides, isn't this law pretty much impossible to enforce? The person who didn't hire someone could give any other reason as to why they didn't hire them?
I'm sorry if this seems offensive, but I'm genuinely curious as to why the gov't is allowed to force people to do things like this. | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/q3j1g/eli5_why_is_it_illegal_to_not_hire_somebody/ | {
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"Access to the public market requires public accommodation. ",
"The technical why?\n\n- Private sector: the commerce clause of the US Const gives power to congress to enact legislation to regulate interstate commerce > employment discrimination affects interstate commerce > congress creates agencies and statutes (most notable is the Civil Rights Act of 1964) that prevent discrimination. This flow can also be followed for most, if not all, states.\n",
"There are no quotas. No one is forced to hire minorities, you just can't discriminate against them. Given a choice between equal white and black candidates you can't choose on race. Many people prefer this because they wanted a society where merit was more important than race.\n\nEven with non-discriminatory practices whites are still hired at greater rates, not due to any overt racism, but because of inherent advantages at birth that mean by the time they get to the job interview and compete with a black candidate, they have a more competitiveness resume and can get the job on merit. \n\nIt is pretty much impossible to enforce on an individual level, but if a company does it enough to establish a pattern then you have a case. ",
"In the USA there are what are called protected classes. A example would be the handicapped but race and religion are also protected. The law is about preventing discrimination. I.E if two people are equally qualified you should hire whoever you want. But if the black dude is more qualified he should get the job assuming experience is the only difference between the two individuals.\n\nThere a couple reason why this is a good idea socially\n\n1.) It's good for buisness as it encourages people to hire the most qualified people.\n\n2.) It prevents tribialism (I.E prevent there being seperate communities of Black, Asian, White, etc people that don't mingle.)\n\n3.) It allow for greater class mobility.\n\nThe law does not say you need to hire minorities. There is nothing stopping a majority individual I.E Rich White dude, sueing if his position is givien to a less qualified individual that is a minority. \n"
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4g93ry | why people trust crystal healing when there is no scientific evidence to support its claims? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/4g93ry/eli5_why_people_trust_crystal_healing_when_there/ | {
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"The same as with most things people believe. There is a lot of anecdotal evidence, and when that evidence is put forward by a source someone already trusts - an actor, a family member, a community leader - the stories are believed without double-blind testing to back them up.",
"Probably because of how incredibly strong the Placebo Effect is. If people believe that what they're doing is beneficial to their health, their health will (in many/most cases) tend to improve as a result. Also, people are likely to ascribe any successes to their chosen homeopathic/ new age cure, and ascribe failures to chance.",
"Because we're looking at the sorts of people who would believe in magic if their friend-of-a-friend said it worked for them. ",
"Why do people believe in God when there is no scientific evidence to support his claims?"
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38nbj3 | Why is it that we are losing helium into space, while hydrogen stays around? | I watched [this](_URL_0_) video a few days back, and it explains why helium is so important and how it's use in party balloons is wasting a finite resource. The scientist explains that earth has too little gravity to keep helium from escaping. How is it that a lighter element, hydrogen, is able to stay on earth? Or do we just have so much in the form of water that we just don't care? | askscience | http://www.reddit.com/r/askscience/comments/38nbj3/why_is_it_that_we_are_losing_helium_into_space/ | {
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"Your intuition is correct. Lighter gases are more likely to escape Earth's gravity. If you look at the [composition of the atmosphere](_URL_0_) you can see that helium is about ten times as abundant as hydrogen.\n\nWhen we purify hydrogen, it's often from electrolysis of water.",
"Helium, a noble gas, is too light to be held under earths gravity. Hydrogen is lighter, and free hydrogen will also escape, however, it is also reactive, and unlike helium, is mostly bound up in compounds with other elements. Free hydrogen will still escape. ",
"I'm super tired, so this won't be the best explanation of what I'm getting at, but it should give you a decent idea.\n\nI'm not entirely sure of the answer, but if I had to guess, I'd say it's probably because helium doesn't react with anything to form compounds (normally), so it stays at the atomic weight for helium, making it the second lightest component of the atmosphere.\n\nHydrogen, on the other hand, very easily forms bonds with oxygen, which means molecular hydrogen isn't very common in the atmosphere. Water is the most abundant source of hydrogen on Earth, and water doesn't float into space like molecular helium.\n\nBoth exist in the atmosphere, but because of how easily hydrogen forms bonds compared to helium, there's much, much more helium in the upper atmosphere, and what hydrogen we do have on the planet is mostly in water or water vapor, and water vapor doesn't exist high enough in the atmosphere to float off into space (at least not in any significant amounts)."
]
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"https://www.youtube.com/watch?v=oZkMQkHGj1s"
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3kihib | Are all elements produced in stars? | I've learned that it takes a star to fuse elements together and make heavier ones.
- At a hight temperature, hydrogen will fuse into helium.
- At a higher temperature (which requires a bigger star), helium will fuse into carbon
- Even bigger stars (at least 8 times the sun) will fuse carbon into neon
and so on.
My question is: is this how all the elements are made? If that's the case, what kind of stars does it take to make gold, lead and uranium? | askscience | https://www.reddit.com/r/askscience/comments/3kihib/are_all_elements_produced_in_stars/ | {
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"No. \n\nOr at least there are some elements that we cannot possibly detect even if they were produced in stars. There are some elements which have extremely short half-lives. Which means that they can be created in laboratories, and there's a very short time within which these can be detected before they decay into other elements. That means that even if they are made within stars or through chance chemical reactions, we wouldn't be able to detect them ( considering the distance and the very short time period they would exist)\n\nEarlier all transuranic elements were thought to be like this, so that they could only be produced synthetically. But now we know that there are those that exist naturally as well (like Plutonium).\n\nThose with atomic numbers above 99 have only been created in laboratories and have not been generated in stars. I think also Technetium (Tc 43) is not present in nature, but not sure about that one. ",
"Fusion is only energetically favorable for elements up to ^(56)Fe, as visualized by this [plot of binding energy vs. atomic mass](_URL_0_). Elements heavier than ^(56)Fe are primarily formed by rapid neutron capture (r-process). This generates very neutron-rich isotopes, which are unstable and undergo beta decay until they become stable isotopes. "
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3b16jz | why do cars need transmissions but planes and boats don't? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/3b16jz/eli5_why_do_cars_need_transmissions_but_planes/ | {
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"Transmissions carry work from the engine to wherever generates thrust. In plane engines and outboard boat motors, this task happens inside the same mechanical unit.\n\nSome inboard boat motors however do have an actual transmission.",
"Some planes and boats can adjust the pitch of their propellors which makes the propellor easier or more difficult to turn which serves a similar function to a transmission.\n\n",
"Engines have a relatively narrow range of RPM where they perform efficiently.\n\nPlanes and boats propel themselves in a viscous atmosphere/fluid. As a result, plane and boat engines can operate in a fairly narrow range of RPM and still be effective. Within that narrow RPM range, the propeller/fan generates sufficient thrust into the viscous atmosphere/fluid to propel the aircraft/boat forward.\n\nOn the other hand, car engines are \"rigidly\" connected to the ground via ground- > tires- > wheels- > driveshaft- > transmission- > clutch- > engine. This means that without a transmission, a car's engine would have to operate on a much wider range of RPM's - including RPM's where the engine performs poorly or not at all. A transmission allows the car engine to remain in its efficient RPM range while the car can travel from a crawl to over 100mph."
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29h95b | How fast does a torus need to rotate to simulate earth gravity? | I was doing the math once and I noticed that the wider the diameter of the torus, the less rotations per minute is needed to simulate artificial gravity. Is this true? Did I do my math right? | askscience | http://www.reddit.com/r/askscience/comments/29h95b/how_fast_does_a_torus_need_to_rotate_to_simulate/ | {
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"You are right. A larger diameter requires a smaller angular speed. The formula is *g = omega*^(2)*r*, where:\n\n* *g* is the Earth's gravity (9.8 m/s^(2))\n* *r* is the radius of the ring\n* *omega* is the angular speed of the ring."
]
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8lctg6 | Why is it called "Missionary position"? Where does the term come from? | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/8lctg6/why_is_it_called_missionary_position_where_does/ | {
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"You may be interested in u/yodatsracist's recent 4-part answer to [I saw an article today claiming that the \"missionary\" position derives its name from Native Americans/Africans who saw missionaries having sex. How true is this?](_URL_0_)"
]
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"https://www.reddit.com/r/AskHistorians/comments/857tu7/i_saw_an_article_today_claiming_that_the/"
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f2w7lp | Are bats the only carriers for Ebola that do not die from it? | I have been doing some research on the Ebola outbreak of 2014-2016 and I cannot find any animals that may have been carriers and not die from it other than bats. Are there any other species I may have overlooked? (If you could also maybe link a source in the comments that would be greatly appreciated!!) | askscience | https://www.reddit.com/r/askscience/comments/f2w7lp/are_bats_the_only_carriers_for_ebola_that_do_not/ | {
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"text": [
"*Technically*, we don't know for certain that bats even are the carriers, although they are the likeliest suspect. [This paper from 2005](_URL_1_) sampled a whole spread of animals to try and find a carrier, so that might help you on your search for different species. \n\nInterestingly, [dogs can become infected](_URL_0_) with Ebola by eating carcasses, but are asymptomatic."
]
} | []
| []
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"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3298261/",
"https://www.nature.com/articles/438575a"
]
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9p168t | what are the rules in the music industry that govern how one artist’s song can be covered by another? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/9p168t/eli5_what_are_the_rules_in_the_music_industry/ | {
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"In the US you make and sell cover versions of other artists' songs \\*without their permission\\* as long as you do certain things, including paying them a fixed rate royalty. Here's a link with more information: [_URL_0_](_URL_0_)\n\n & #x200B;\n\nThere is a slightly different process for cover bands that are preforming live versions of someone else's music. You need to pay a fee to ASCAP which is an organization that collects royalties for songwriters. Usually the venue where the cover band performs will have a blanket ASCAP license that covers any cover songs a band it likely to play. ",
"You pay a royalty - you can either ask permission beforehand and negotiate a rate, or just do it and pay the standard rate. Recording royalties are based on sales, while performance royalties are usually covered by a performance fee to ASCAP. Royalties go to the songwriter(s), not the band, because the band might have been covering someone else's material in the first place (for example, Elvis Presley didn't write any of his own songs)."
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1kg29b | why do we have ear lobes ? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1kg29b/eli5_why_do_we_have_ear_lobes/ | {
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"The general shape of our ears actually helps us determine the direction of sounds, as they reflect sounds differently based upon where they are coming from. If you change the shape of someone's ear then it takes a little bit for their brain to learn how to interpret the echoes properly again. ",
"Where else would you put your 00 gauge plug? - WAIT! Don't answer that, I don't want to know.\n\nThere is no known biological function for the ear lobe.",
"It's a handle for your mother."
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787sz3 | Life in 1910, London | I'm writing a narrative set in that time period, so every bit of information about how life was for the majority of the poppulace will be much apreciated, things like:
- Where life conditions good ?
- People where happy ?
- How much did the Industrial Revolution still affected the city and it's people ?
- Public services like, police, sewer, garbage collection, etc. They existed, and if they did, what the people tought of them ?
- How was the art production ?
I know that in 1910 europe was just exiting the "Belle Epoque" period, and that four years later the "War to end all wars" would start, how was the mood around england during that time period ?
Again, i'm planning to write a suspense novel set in that time period, i love history with all my hearth and already looked up a lot of books, documentaries and films to help me see as clearly as possible how London was in that time period. My problem is, i am having dificult to find small history accurate details about how the people lived, so i come to you, my fellow history lovers, to help me recreate, as accurate and as fair as possible, the llife, the city and the people of that period. | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/787sz3/life_in_1910_london/ | {
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"We've allowed this post, but you're unlikely to get a thorough answer. Questions like \"were life conditions good?\" and \"were people happy?\" are not really answerable: some people had a high standard of living and some did not; some people were happy most of the time and some were desperately unhappy, with every nuance in between. People in good circumstances had personal setbacks that made them unhappy, and people in desperate circumstances had times of joy.\n\nI would recommend that you pose your more concrete questions to the sub separately:\n\n*What sort of art was being produced in England around 1910? What decorative arts movements were relevant?*\n\n*How was garbage and sewage collected in early twentieth century England?*\n\n*How common was electricity in England in 1910? When did \"ordinary people\" start to have access to it?*\n\nFor the overall view of the period, I think you will find *Edwardian England: A Guide to Everyday Life, 1900-1914*, by Evangeline Holland, useful. It seems to be a well-researched guide to politics and popular culture, and may help you get more specific questions to ask. "
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cd0evh | Why is strep throat, caused by a commensal bacteria, contagious? | I went to my doctor and was diagnosed with strep throat. I was told that after 24 hrs of antibiotics my strep throat won't be contagious. I was also told that strep is commensal and opportunistic, and a secondary infection to my viral cold. I had a break in the barrier that normally keeps the Group A strep from accessing nutrients, but the changes in conditions caused by my cold meant that my normally chill bacteria started growing out of control. I know contagiousness is due to active bacteria being spread and causing infection in others, but what I don't get is that everyone has Streptococcus pyogenes living commensally in/on them, so how can it be "spread"? It's only causing an infection in me because my barriers broke down, but surely for someone else who's healthy and hasn't had a cold that weakens their innate protection it wouldn't be an issue?
TL;DR why is strep "contagious" when everyone has it anyway? | askscience | https://www.reddit.com/r/askscience/comments/cd0evh/why_is_strep_throat_caused_by_a_commensal/ | {
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"Because there are different forms found in different people much like blood types, therefore it is fine for yourself to carry but not other people\n\nThe exact reason strep throat is contagious.\nBecause if a new type of streptococcus is found the body sends infection markers and can be potentially fatal if it's not your own type"
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n5vjh | could it be possible that a black hole in our universe turns out to be a big bang in some other universe? | It seems like this idea could account for the spontaneity of the big bang. | askscience | http://www.reddit.com/r/askscience/comments/n5vjh/could_it_be_possible_that_a_black_hole_in_our/ | {
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"[There's a Polish cosmologist who thinks this might be possible.](_URL_0_)\n\nIt's totally untestable, though. At least, for a very long time.",
"This is actual a concept/idea that is being tossed around.\n\nThe idea is that all matter compresses down to a single infinitely dense and infinitely small point. What's on the 'other side' of that hole? Some scientists have come up with the concept of a ['white hole'](_URL_0_). It's all very theoretical, but some of the great minds (like Stephan Hawking) have considered it.",
"[There's a Polish cosmologist who thinks this might be possible.](_URL_0_)\n\nIt's totally untestable, though. At least, for a very long time.",
"This is actual a concept/idea that is being tossed around.\n\nThe idea is that all matter compresses down to a single infinitely dense and infinitely small point. What's on the 'other side' of that hole? Some scientists have come up with the concept of a ['white hole'](_URL_0_). It's all very theoretical, but some of the great minds (like Stephan Hawking) have considered it."
]
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"http://news.nationalgeographic.com/news/2010/04/100409-black-holes-alternate-universe-multiverse-einstein-wormholes/"
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"http://en.wikipedia.org/wiki/White_hole"
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1lfuxz | How big is our solar system in non-planar directions (up & down rather than out) | All info I've ever read about the size of our solar system seems to refer to a flat disk area (like the galaxy), but is it in really more of a sphere that has the majority of its orbiting bodies in that planar area?
Secondarily, if it truly is flat, could we have sent Voyager 1 up or down rather than "out" to reach the edge of the solar system much sooner? Though if we did this, we'd obviously miss all the amazing planetary flyby shots Voyager got.
| askscience | http://www.reddit.com/r/askscience/comments/1lfuxz/how_big_is_our_solar_system_in_nonplanar/ | {
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"I can't answer your actual question but Voyager 1's mission wasn't to leave the solar system. It was to photograph the solar system and we were lucky that we launched when we did because it's a very rare occasion (not sure exactly how rare but I think it's hundreds of years at least) that we can take advantage of planetary alignment to slingshot the Voyagers across the solar system. ",
"Most of the mass orbits in the same plane but there is stuff that doesn't. Pluto's orbit, for example, is tilted 17° to the plane, while long period comets can have any inclination. So there is \"stuff\" all around, just far less of it outside the plane. \n\nAs to the \"edge\" of the solar system it depends what exactly you see this as but if you consider it as the heliopause, where the stellar wind meets the interstellar medium, then that is spherical (the heliosphere); the sun emits stellar wind in all directions not just in the plane of the planets, so it is the same distance away from the sun whichever way you go. \n\nIt would actually take substantially *longer* to reach the heliopause going straight \"up\" as a probe would be unable to make use of gravitational slingshot manoeuvres off planets to increase speed; most of Voyager's speed comes from this, not its launch propulsion.\n\nBut note its all pretty empty up there, the distinction between \"inside\" and \"outside\" the solar system is really very subtle if you are talking about the space rather than actual bodies orbiting the sun. ",
"blorg is on the right track except for two things:\n\n1) The heliopause (and associated other surfaces between the solar wind and the interstellar medium [ISM]) is thought to be more comet shaped than spherical. The sun is moving through the ISM, and thus toward the nose it is more compressed, and in the opposite direction it has a long tail. \n\n2) While the difference between the inside and outside of the heliopause would be hard to detect if you were just floating around out there, the characteristics of the material (magnetic field strength and orientation, ionization state, density, temperature...) are really quite different, which is why it's exciting as Voyager starts to encounter the effects of the ISM as it reaches the edge of the solar system. "
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briy0t | In the early 19th century why did it take so long for major powers to adopt the rifle over the musket? | There were riflemen units in the Napoleonic and American revolution wars but the standard solider had a musket. Was it a matter of production or pride in the musket? | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/briy0t/in_the_early_19th_century_why_did_it_take_so_long/ | {
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"One piece of the puzzle was ammunition design. Until the introduction of bullets like the Minie Ball, loading a rifled musket was a difficult, time-consuming endeavor. With the round ball that was standard for ammunition at the time, the ball was close to the same size as the bore, with wadding used to provide a tighter seal and help hold the ball in the gun until fired. Unfortunately, for rifling to work, it needs a tighter fit between bore and ball to allow for the rifling to engage the ball effectively. \n\n & #x200B;\n\nModern rifling gives some idea of how tight you need the seal to be for the best effect. American 30-06 M2 Ball of WW1 vintage had bullets 0.3086 inches in diameter. Standard bores, however, were .300 inches in diameter, while the rifling grooves were about 0.005 inches deep. The result is that the bullet ends up being formed to the rifling, and on fired bullets the imprint of the rifling is generally very clear on the bullet.\n\n & #x200B;\n\nGoing back to muzzle-loaders, the problem becomes pretty apparent. Rifled muskets pre-Minie Ball didn't have as tight a fit to the bore as modern rifles, but they still used a significantly tighter fit than a standard smoothbore and thus became significantly more difficult to load. That translated to slower rates of fire and ultimately resulted in something that was found to be unsatisfactory for standard line infantry.\n\n & #x200B;\n\nThat's where the Minie Ball comes in. The Minie Ball and systems like it made muzzle-loading rifles practical by being small enough to fit down the bore easily like on a smoothbore and expanding upon firing to engage the rifling. For the Minie Ball, this was accomplished by a cavity in the back of the bullet that would be forced outwards by the pressure of the expanding gases. Though not perfect by modern standards, it finally provided armies with a bullet that could be loaded as easily as an old smoothbore musket but work well with rifling. These new types of ammunition also afforded some other beneficial side effects, including higher velocities (thanks to a better gas seal) and longer effective ranges thanks to not only the use of rifling, but their more aerodynamic shape. These types of ammunition were developed in the 1830s and 1840s, and relatively soon afterwards is when we see armies all over the world adopting rifled muskets like the Pattern 1853 Enfield and Springfield Model 1855.",
"Rifles achieved their increased accuracy by taking a small lead ball (the bullet) and wrapping it in a wad of cloth (usually felt). The felt wad would then grip the spiral grooves of the bore which would in turn \"spin\" the bullet as it traveled down the barrel, this spin stabilized the ball as it traveled through the air toward its target leading to an increase in accuracy. The increased accuracy of the rifle was an obvious advantage, but not without its consequences. These rifles were more costly to produce and a smaller number could be made owing to the need for specially trained gunsmiths to manufacturer them; tens of thousands of the famous Pennsylvania (Kentucky) long rifle were made, but in that same time millions of the standard \"Brown Bess\" musket were produced. Second, for a rifle to be effectively employed required specialized training and experience in handling and using the rifle, this was not a weapon for the common infantry man. The rifle was the weapon of choice for hunters, sharpshooters, and Jägers. The rifle holds a special place in the American psyche because it was the weapon for the individual, not the closed ranks of most military formations. There is also the issue of the rifles battlefield performance, trained rifleman could get off roughly two shots (optimistically) in the time it took a man armed with a musket to fire three shots. In close range fighting between lines of infantry volume of fire is more important than individual accuracy. A rifleman would spend considerable time just trying to back the tightly wrapped lead ball into the barrel of his rifle, often times relying on a small mallet to drive it in. Rifles also commonly lacked a bayonet plug on the end of the barrel which would be used to affix...a bayonet. In hand to hand fighting or in repelling cavalry the advantages afforded by the reach of a bayonet and its use by closed formation of infantry was considerable. And over time after repeated firing in battle gunpowder residue would build up in the barrel reducing the accuracy of the rifle until it was cleaned, not something you want to do in the middle of a firefight.\n\n & nbsp;\n\nRifles were not exclusive to the American continent, the Austrians had introduced the Girandoni air rifle in 1780, the Germans had their famous Jäger light infantry, and the British had introduced the Baker rifle in 1800. The Girandoni air rifle was expensive and somewhat difficult to use while the Baker rifle solved many of the problems associated with muzzle loading rifles, it was still only produced in small number owing and used by specially trained soldiers. What was needed was a weapon that could be manufactured cheaply and in great numbers and was easy enough to use that even a common infantry man could do it. Something that often goes overlooked is the issue of battlefield command and control. You'll notice that previously rifles were almost exclusively used by specialist military units (riflemen, sharpshooters, light infantry, etc.) Men were selected for these units because of their technical skills, physical stamina, and self reliance. Light infantry ere expected to operate in rough terrain over great distances away from the main body of the army. But when battle was joined between two armies it would take thousands of officers and non-commissioned officers to effectively maneuver tens or hundreds of thousands of men in tight formations, (individualists need not apply). The battlefield was a chaotic and smokey arena, its why soldiers wore such brightly colored and distinct uniforms. It was hard enough to see what you were firing it or who was firing at you, and near impossible to even see individual targets. The infantry regiment was simplest and easiest method of commanding a few hundred men to move together and ideally all fire at the same target at the same time. Their volume and weight of fire as a massed formation was what gave the infantry their killing punch.\n\n & nbsp;\n\nHowever, the landscape of infantry combat changed dramatically in 1847, the year French officers Claude-Étienne Minié and Henri-Gustave Delvigne introduced their conical-cylindrical bullet with a hollow base, hence known as the \"Minié ball\". Compared to earlier rifle technology the Minié ball was revolutionary for both its ease of use and economics. The Minié ball would be loaded into the muzzle of a rifle base first (pointy end up) and when fired the rapidly expanding and super heated gasses of the powder charge would fill and expand the base of the Minié ball allowing it to then grip the grooves the rifling. Minié balls were easy and cheap to manufacture in tremendous numbers, they were simply cast lead. The industrial revolution increasingly made the manufacturing of rifles cheap and easy, and even muskets were converted into rifles by milling grooves into their barrels. The Minié ball was also easy to use for even the common infantry soldier, it could be loaded into the muzzle of his rifle and rammed down the barrel in much the same way a musket would be loaded."
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9pvgd2 | the difference between piston plane engines and car engines | As far as I understand, they work similarly, so why are plane engines more complicated to start / more expensive / require maintenance more often / etc. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/9pvgd2/eli5_the_difference_between_piston_plane_engines/ | {
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"if car engine breaks down, you putter to side of the road and call AAA.\n\n & #x200B;\n\nif your plane engine breaks down, you fall out of the sky and call FAA. \n\n & #x200B;\n\nif you maintained your car engine at same level of your plane engine, you'd be doing inspection every morning before leaving for work. oil changes every month, certified mechanic inspections every year. ",
"A plane engine is built for power density, a normal car engine is built for reliability\n\nFor a daily drive you really just want moderate performance in a reliable package. It doesn't particularly matter if the engine is 110 or 130 horse power or if its 10 kg heavier, it'll still work just fine for a daily driver. For a plane, you want an engine powerful enough to get you moving and light enough so you can still take off, this requires some trade offs that are more inline with racing engines than daily drivers. A propeller powered aircraft may have a power to weight ratio on the order of 1 kW/kg, but a sports car engine(no body) may have a power to weight ratio at the same level so planes are looking for far more performance out of the same sized package which means more stress and less reinforcement\n\nYou end up with the same odd maintenance requirements whenever you get to any high power density engine. GT3 cars(mid tier racing cars) have engines rated for about 60 hours of racing, and back in 2005 Formula One cars couldn't use more than 1 engine every 2 races(they were using a whole new engine), they're now restricted to three engines in a season. Races are only 305 km....\n\nAny system trying to eek every last bit of performance out ends up with maintenance and reliability issues because durable systems are heavier and the durability isn't necessary in these scenarios."
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l6qgo | Has there ever been a mathematical "Piltdown Man"? That is, a mathematical theorem that was accepted as valid for many years, only to have a fatal flaw discovered much later? | askscience | http://www.reddit.com/r/askscience/comments/l6qgo/has_there_ever_been_a_mathematical_piltdown_man/ | {
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"Not to insult the folks here, but you could try x-posting over at /r/math.",
"There have been several mathematical theorems that had proofs or claims thereof that contained flaws that were later fixed. However, I can't think of an example where a theorem was \"proven\" with a flawed proof and (much) later shown to be wrong.\n\nOne interesting related anecdote I can think of is due to the advance of AI: A long open problem in checkers that was thought to be solved turned out to have a wrong solution. The original problem, the incorrect solution, and the correct solution (due to AI) were separated by about a century each! [Here is the link](_URL_0_)",
"Wikipedia has a partial [list of several examples]( _URL_0_)",
"There are discussions about this [here](_URL_7_) (and the opposite case, [here](_URL_2_)) full of (quite-technical) examples for which copying & pasting would be redundant. They're partially collated on [this page](_URL_4_), apparently. Nevertheless, I like [Malfati's Problem](_URL_0_), which is simple to understand but had its original solution proven completely wrong 150+ years after being published (although for most of that time nobody was trying to, and it was never exactly a cornerstone of modern mathematics).\n\nI don't know if Piltdown Man was the best comparison to make, by the way. If nothing else, these aren't outright hoaxes - the errors were from incorrect assumptions, gaps/exceptions in incomplete proofs or just mistakes - and none really gained the same exposure or public attention. If a paper comes along with similarly big implications (\"The set of real numbers is countable! I have an elementary proof of Fermat's Last Theorem! There's another integer between 3 & 4!\")... it's easier to check the evidence yourself in mathematics than it was in 1950s paleontology^1. If I can indulge my opinion for a moment, math is right in the 'sweet spot' of avoidance - it doesn't have the errors of experimental data and chance that can affect just about all scientific fields, but it's not as far-removed as pure Philosophy where almost nothing is truly certain.\n\nKnowing nothing of your level of mathematical knowledge, I suppose it does no harm to mention [Gödel's Incompleteness Theorem(s)](_URL_1_)(more Gödel ELI5: [1](_URL_6_), [2](_URL_3_)) - which *grossly* simplified means there will always be statements that are true but cannot be proven so. Mathematics can't be 'finished'. That is, it's impossible to have a perfect world - short of having a computer that can count to infinity in ten seconds^2 and check every case individually, there will always be theorems that cannot be proven and assumptions that have to be made^3. And it's hardly a stretch of the imagination to imagine that some day one or two of those turn out to be wrong after all.\n\n1. Though that doesn't mean it's *easy*... The foremost example being Fermat's Last Theorem, which took three centuries and the creation of new branches of mathematics to be proven true, or the Four-Colour Theorem which used a computer to individually check nearly two-thousand specific examples after first proving that those were all the possible variations.\n2. Which, since that's impossible, becomes a [whole other problem](_URL_5_).\n3. This is still a gross simplification, but I'm okay with it now.\n4. Markdown is really irritating sometimes",
"Euclid claimed that tetrahedra could be close packed to fill a volume, but in the early renaissance it was realized that his proof was flawed, and it wasn't until 2010 that someone found that they could only be packed to below something like 1-10^-58",
"Well, it's kind of mathy, but in cryptography the [Needham-Schroeder Public Key protocol](_URL_0_) was proven secure, and subsequently shown to be vulnerable to attack, causing us to have to rethink what it means to prove something secure. Probably not what OP had in mind though",
"The [\"Piltdown Man\"](_URL_0_) was completely falsified and is considered a hoax. This is different than a theorem that was accepted until proven false (which happens all the time in science). Unfortunately the Piltdown Man was knowingly faked (by its creator(s)) from the beginning.",
"Fermat's last theorem has this flavor, This guy spent 9 years in his attic trying to prove the theorem, thought he did, only to realize that previous work was shaky. Not maliciously shaky, as in piltdown, but thats how science works.\nfrom Wikipedia:\n\nBy mid-1993, Wiles was sufficiently confident of his results that he presented them in three lectures delivered on June 21–23, 1993 at the Isaac Newton Institute for Mathematical Sciences.[112] Specifically, Wiles presented his proof of the Taniyama–Shimura conjecture for semistable elliptic curves; together with Ribet's proof of the epsilon conjecture, this implied Fermat's Last Theorem. However, it soon became apparent that Wiles' initial proof was incorrect. A critical portion of the proof contained an error in a bound on the order of a particular group. The error was caught by several mathematicians refereeing Wiles' manuscript,[113] including Katz, who alerted Wiles on 23 August 1993.[114]",
"Not to insult the folks here, but you could try x-posting over at /r/math.",
"There have been several mathematical theorems that had proofs or claims thereof that contained flaws that were later fixed. However, I can't think of an example where a theorem was \"proven\" with a flawed proof and (much) later shown to be wrong.\n\nOne interesting related anecdote I can think of is due to the advance of AI: A long open problem in checkers that was thought to be solved turned out to have a wrong solution. The original problem, the incorrect solution, and the correct solution (due to AI) were separated by about a century each! [Here is the link](_URL_0_)",
"Wikipedia has a partial [list of several examples]( _URL_0_)",
"There are discussions about this [here](_URL_7_) (and the opposite case, [here](_URL_2_)) full of (quite-technical) examples for which copying & pasting would be redundant. They're partially collated on [this page](_URL_4_), apparently. Nevertheless, I like [Malfati's Problem](_URL_0_), which is simple to understand but had its original solution proven completely wrong 150+ years after being published (although for most of that time nobody was trying to, and it was never exactly a cornerstone of modern mathematics).\n\nI don't know if Piltdown Man was the best comparison to make, by the way. If nothing else, these aren't outright hoaxes - the errors were from incorrect assumptions, gaps/exceptions in incomplete proofs or just mistakes - and none really gained the same exposure or public attention. If a paper comes along with similarly big implications (\"The set of real numbers is countable! I have an elementary proof of Fermat's Last Theorem! There's another integer between 3 & 4!\")... it's easier to check the evidence yourself in mathematics than it was in 1950s paleontology^1. If I can indulge my opinion for a moment, math is right in the 'sweet spot' of avoidance - it doesn't have the errors of experimental data and chance that can affect just about all scientific fields, but it's not as far-removed as pure Philosophy where almost nothing is truly certain.\n\nKnowing nothing of your level of mathematical knowledge, I suppose it does no harm to mention [Gödel's Incompleteness Theorem(s)](_URL_1_)(more Gödel ELI5: [1](_URL_6_), [2](_URL_3_)) - which *grossly* simplified means there will always be statements that are true but cannot be proven so. Mathematics can't be 'finished'. That is, it's impossible to have a perfect world - short of having a computer that can count to infinity in ten seconds^2 and check every case individually, there will always be theorems that cannot be proven and assumptions that have to be made^3. And it's hardly a stretch of the imagination to imagine that some day one or two of those turn out to be wrong after all.\n\n1. Though that doesn't mean it's *easy*... The foremost example being Fermat's Last Theorem, which took three centuries and the creation of new branches of mathematics to be proven true, or the Four-Colour Theorem which used a computer to individually check nearly two-thousand specific examples after first proving that those were all the possible variations.\n2. Which, since that's impossible, becomes a [whole other problem](_URL_5_).\n3. This is still a gross simplification, but I'm okay with it now.\n4. Markdown is really irritating sometimes",
"Euclid claimed that tetrahedra could be close packed to fill a volume, but in the early renaissance it was realized that his proof was flawed, and it wasn't until 2010 that someone found that they could only be packed to below something like 1-10^-58",
"Well, it's kind of mathy, but in cryptography the [Needham-Schroeder Public Key protocol](_URL_0_) was proven secure, and subsequently shown to be vulnerable to attack, causing us to have to rethink what it means to prove something secure. Probably not what OP had in mind though",
"The [\"Piltdown Man\"](_URL_0_) was completely falsified and is considered a hoax. This is different than a theorem that was accepted until proven false (which happens all the time in science). Unfortunately the Piltdown Man was knowingly faked (by its creator(s)) from the beginning.",
"Fermat's last theorem has this flavor, This guy spent 9 years in his attic trying to prove the theorem, thought he did, only to realize that previous work was shaky. Not maliciously shaky, as in piltdown, but thats how science works.\nfrom Wikipedia:\n\nBy mid-1993, Wiles was sufficiently confident of his results that he presented them in three lectures delivered on June 21–23, 1993 at the Isaac Newton Institute for Mathematical Sciences.[112] Specifically, Wiles presented his proof of the Taniyama–Shimura conjecture for semistable elliptic curves; together with Ribet's proof of the epsilon conjecture, this implied Fermat's Last Theorem. However, it soon became apparent that Wiles' initial proof was incorrect. A critical portion of the proof contained an error in a bound on the order of a particular group. The error was caught by several mathematicians refereeing Wiles' manuscript,[113] including Katz, who alerted Wiles on 23 August 1993.[114]"
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"http://mathoverflow.net/questions/27749",
"http://www.reddit.com/r/explainlikeimfive/comments/j3nx0/eli5_g%C3%B6dels_incompleteness_theorems/",
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"http://en.wikipedia.org/wiki/P_versus_NP_problem",
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4d6i4w | How was FDR's decision to run for a third term received by the Democratic Party? By his 4th election was there "Roosevelt Fatigue"? | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/4d6i4w/how_was_fdrs_decision_to_run_for_a_third_term/ | {
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"To ask a follow up question if I may - why was he constitutionally allowed to run for a third term and then a fourth? \nEDIT: Thanks for the replies - question answered.",
"Follow up question - How much did WWII play in the decision to run, if any?",
"Follow-up question: What was the political sentiment when the amendment was first introduced? How did Congress know that there was political will to pass it when America has just re-elected FDR?",
"Roosevelt’s decision to run for a third term was heavily influenced by the foreign affairs of the time re: Germany and the struggle of the British to defend and fight back. The national sentiment towards isolationism, especially among politicians, ultimately convinced Roosevelt to seek a third term. He viewed this less as a political coup and more as a necessity to prepare the nation for war. \n\nIf anything, the Democratic Party was happy he chose to run due to Wilkie’s popularity (the Republican nominee) at the time.\n“When the delegates to the DNC convened in Chicago on July 15, 1940, there was no serious doubt he (Roosevelt) would accept the renomination.” \n\nThat’s not to say the the whole of the Democratic party rallied right away around Roosevelt. Roosevelt did not attend the convention and preferred to have his associates Perkins, Hopkins, and Ickes take care of things in Chicago. Roosevelt did not want to come out right away and declare that he wanted to nomination, so he literally played a game of telephone with Kentucky Senator Barkley, an old-timer who had a penchant for delivering emotional keynote addresses that brought the people to a frenzy. He too gave a keynote in 1940 ending with a personal note from Roosevelt: “The President has never had, and has not today, any desire or purpose to continue in the office of President, to be a candidate for that office, or to be nominated by the convention for that office. He wishes in earnestness and sincerity to make it clear that all of the delegates in this convention are free to vote for any candidate.”\n\nI’ll quote directly from FDR here: “The vast crowd in Chicago Stadium was speechless for a moment. What did Roosevelt mean? The statement said neither yes nor no. Five, ten, fifteen seconds, and then bedlam broke loose. From loudspeakers all over convention hall a powerful voice boomed out “WE WANT ROOSEVELT. WE WANT ROOSEVELT,” over and over. \n\nRoosevelt did not really want to run for a fourth term unless the war was still going on - as he was in terrible health. That being said he made his intentions clear early on this time around: “he put his cards on the table early. In a message to party chairman Robert E. Hannegan well over a week before the delegates would assemble, the president said that although he did not wish to run, his duty compelled him to do so. ‘Reluctantly, but as a good soldier, I will accept and serve in this office, if I am ordered to do so by the Commander In Chief of us all - the sovereign people of the United States.” \n\nHe won renomination on the first ballot.\n\nAll info taken from Jean Edward Smith’s fantastic “[FDR](_URL_0_)” \n"
]
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"https://www.worldcat.org/title/fdr/oclc/71350593&referer=brief_results"
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2wroyj | what keeps a panting dog from hyperventilating ? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2wroyj/eli5_what_keeps_a_panting_dog_from/ | {
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"Panting in dogs tends to be shallow breaths an they're not moving a ton of air, which prevents them from blowing off all their carbon dioxide (CO2) and getting respiratory alkalosis (high blood pH which causes an acid/base imbalance). But not always... dogs that are taking fast, deep breaths will suffer from the same hyperventilation syndrome as people. The body is more sensitive to a build-up of CO2 to tell us when to breathe than a lack of oxygen. Hyperventilating causes you to expel more CO2 than usual which will cause your body to stop signaling you to take a breath and you won't get sufficient oxygen. It also causes alkalosis where the blood pH increases. A dog panting regularly isn't moving more air than a dog taking in slower, deep breaths, so hyperventilation isn't an issue. The issue comes when there is labored breathing or heavy panting, which will cause these issues. Dogs are also more prone to aerophagia, where they gulp air while panting heavily and distend out their stomachs. Aerophagia can rarely lead to bloat, but can be quite uncomfortable. Questions?",
"The other part to this is that there is part of each breath which does not take part in gas exchange. This is that part of the breath which only reaches the upper airways rather than the lungs. This part of the airway is called the dead space and so what panting does is move air in and out of the dead space which because it doesn't reach the lungs doesn't drop the CO2"
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2bqsf2 | Did the Union Jack ever have a red background with a blue central cross? | [This illustration](_URL_0_) is often used to represent events on [evacuation day](_URL_1_) in Massachusetts. The flag fluttering to the ground is the flag the British Army left there but the colors look the opposite of how the Union Jack typically looks. Was there ever a flag like this that the British flew? | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/2bqsf2/did_the_union_jack_ever_have_a_red_background/ | {
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"No. The Union Jack has only ever had a red cross (from the flag of England) and a blue background (from the flag of Scotland). Whoever coloured this image made an error. And whoever drew it too, for that matter. The British flag being lowered seems to be an illustration of the *current* Union Jack, which was adopted in 1801 after the Union with Ireland. In 1783 it would have looked [like this](_URL_0_)."
]
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"http://i282.photobucket.com/albums/kk250/josmndsn/evacuationofnewyorkbythebritish.jpg",
"http://home.roadrunner.com/~montghistory/VanArsdale112008.pdf"
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"http://www.crwflags.com/fotw/images/g/gb-1606.gif"
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293ryd | why are we training so many kids to code? | There are over 600,000 kids currently learning to code and the numbers are rising. I fear continuing to teach my kids as they will end up with low paying jobs even if they are great due to oversupply. Please explain where the demand will come from especially when overseas labor can do the work for less. I am located in the U.S. | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/293ryd/eli5why_are_we_training_so_many_kids_to_code/ | {
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"We teach all kids history, it doesn't make them grow into historians. (It doesn't even grow many of them into history-aware people, kids forget most of what they learn or never gain much competence at it anyway.)\n\nAdditionally a lot of the cheaper overseas folk are sub-par programmers too. ",
"It's the combination of the age-old political hot button \"we must improve education\" mixed with the current belief that only \"computer jobs\" will remain during/after automation.",
"[This article](_URL_0_) has a pretty good argument as to why people should learn to code: ",
"It is not so that they all go and become programmers; it is because programming helps instill a certain logical way of approaching problem that is applicable in almost any situation. A well taught basic programming course should focus almost exclusively on the logic, not the language (the language is a method to gauge how the student understands the logic - this is why languages like Turing and basic are good; they allow for the logic rather than the intricacies of the language to determine the output); if the logic is taught well and the students are shown how to apply it, then it can be applied in almost any situation. For example, let's say you are working on a car. You have a problem where the steering wheel shakes back and forth as you drive. To begin with, you determine what can cause the symptoms (loose tie rod, worn wheel bearing, worn steering gear, bad ball joints...). The next step is to see how to narrow it down (the wheels don't have any play, hub and ball joints are good, the tie rods are tight, but when the steering wheel is turned, the steering box gets the input, but doesn't provide any output): the steering box is broken.\n\nAfter you have ruled out the possibilities, you then are left with the (most likely) solution. This method of thinking can be used to solve almost any problem of any size by breaking it down into it's component parts and testing each individually. In the end, programming is essentially applied problem solving, and it gives skills that can be used no matter what field they end up working in.\n\nTL;DR: We are raising a generation of Vulcans."
]
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[],
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"http://www.motherjones.com/media/2014/06/computer-science-programming-code-diversity-sexism-education"
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9b3z7w | why is a sugary drink sticky when spilled, but an artificially sweetened one not? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/9b3z7w/eli5_why_is_a_sugary_drink_sticky_when_spilled/ | {
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"Artificial sweeteners are much more concentrated. So, when they dry out, there is less leftover. ",
"Sugary drinks contain sugar, which is highly attracted to water. Even when the spilled drink \"dries,\" it's not completely dry. The sugar in the liquid (which of course does not evaporate like water), is still holding onto a lot water molecules causing a sticky feeling. Essentially, a spilled sugary drink is a dilute syrup. Now, diet drinks have a far less concentration of sweetener, thus, they are much less sticky."
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2zu37a | Benedict Arnold is regarded as the biggest traitor of the American Revolution. I've heard that he was treated poorly by America beforehand though. What's his story? | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/2zu37a/benedict_arnold_is_regarded_as_the_biggest/ | {
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"[Here's a previous thread](_URL_0_) with a response by /u/zuzahin that goes in-depth into Arnold's story and motivations."
]
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[
"http://www.reddit.com/r/AskHistorians/comments/1u8mvr/what_is_the_truth_regarding_benedict_arnold_why/"
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6sf7rp | why are puns generally frowned upon (albeit humorously)? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/6sf7rp/eli5_why_are_puns_generally_frowned_upon_albeit/ | {
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"Because they're low effort, short jokes. They're like a reddit shit post. It can be funny, but it can't be elaborate and abstract.",
"Yer not alone in askin', and kind strangers have explained:\n\n1. [Do people actually hate puns or do they just pretend not to like them whenever they hear one? ](_URL_1_)\n1. [Why are puns considered \"bad\" jokes? ](_URL_0_)\n1. [ELI5: Why do people hate puns so much? I feel like they can be some of the most clever forms of jokes. ](_URL_2_)\n1. [Why are puns considered \"bad\"? ](_URL_3_)\n",
"because groaning and rolling your eyes is the response we hope for when we make a terrible pun. It's basically applause",
"Puns are like the Country Music of jokes:\n\nThere is a section of the community who absolutely love them, but the majority hate them (or at least profess to). They would say (with some justification, perhaps) that they are shallow, repetitive, and have little artistic merit.\n\nAnd while that is true of the majority, the best ones can really make you think.\n\nIt's no coincidence, I think, that puns proliferate in the titles and lyrics of country songs: All Over Me; Cleopatra, Queen of Denial; There Goes my Life; She Let Herself Go; I Can't Love You Back etc, etc.\n\nTl;dr: Puntry Music"
]
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"https://www.reddit.com/r/NoStupidQuestions/comments/51flcm/why_are_puns_considered_bad_jokes/",
"https://www.reddit.com/r/NoStupidQuestions/comments/3khkwl/do_people_actually_hate_puns_or_do_they_just/",
"https://www.reddit.com/r/explainlikeimfive/comments/2cyt12/eli5_why_do_people_hate_puns_so_much_i_feel_like/",
"https://www.reddit.com/r/NoStupidQuestions/comments/3c2yer/why_are_puns_considered_bad/"
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1syhs2 | why does it seem that most movies have a "happy" ending? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1syhs2/eli5_why_does_it_seem_that_most_movies_have_a/ | {
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"Because most people like happy endings.",
"Why would you want to leave the theater depressed? The point is to have a closing that let's you leave on a positive note. There are French (and of course other places) movies however, that end without happiness. ",
"Most movies the writer has a specific story to tell and the ending is determined by the story. Take a movie like Fever Pitch. It doesn't matter that the Red Sox won the Series the year the movie was made. It only matters that the boy-meets-girl, boy-loses-girl, boy-wins-girl story be told. The movie re-shot and added a couple scenes to reflect the Sox in the Series. \n\nCounter that with a movie like Suicide Kings. It has a dark ending. A couple different endings were shown to test audiences and the highest ratings were for the dark ending. \n\nAnother example would be the Jennifer Anison/Vince Vaughn flick, The Break Up. That had a happy ending that the test audiences didn't like. It was re-shot and the less happy ending was added. \n\nSo, the movie ends how the film-maker and the audience want the movie to end. ",
"Because that's how the story telling formula works.\n\nMeet the hero. Hero faces adversity. Hero overcomes adversity.\n\nThat is 90% of all movies (and TV shows and books) out there. "
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2up5za | How popular were the Odyssey and the Iliad in Ancient and Classical Greece? | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/2up5za/how_popular_were_the_odyssey_and_the_iliad_in/ | {
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"hi! you may be interested in these posts\n\n* [how commonly known would the story of the Iliad, have been in the second century BC classical world?](_URL_3_)\n\n* [How well known would the stories in the Odyssey have been to the average Greek citizen at the highest point of its popularity?](_URL_2_)\n\n* [How influential were Homer's works The Iliad and The Odyssey throughout history and how would the world be different if those stories never existed?](_URL_1_)\n\n* [Are the Iliad/Odyssey and the Epic of Gilgamesh famous for still existing or were they the best of their age?](_URL_4_)\n\nof possible tangential interest\n\n* [Did the ancient Greeks view Homer's Iliad and Odyssey as fact? How historical are these two works?](_URL_0_)\n\n* [Were stories such as The Iliad and The Odyssey considered religious \"text\" in ancient Greece?](_URL_5_)",
"For these works to have survived for so long, it must be assumed that they were popular, but in a different sense than you might think. To understand their popularity we have to note two things: First that it is accepted that these works were originally told orally, and were later written down into more or less the form we have today. Second is that for the works to survive to today they must have been written down several times in several places. \n\nThe First Part: This is called Oral-formulaic Composition and was first noted by Milman Parry and Albert Lord in what would later be called the Parry-Lord Theory. This theory essentially stated that epics were NOT originally written down, but instead passed down through oral tradition, particularly through bards. These bards remembered the key plot points of the stories (e.g. Achilles killing hector, or Patroclus' aristeia), and then filled in the rest of the details as they sang. If you read certain translations of the works, you will notice how they could do this. Things like \"swift-footed Achilles\" or \"Enduring Odysseus\" are repeated often and are examples of how the bards might sing the song while maintaining meter and reminding the audience of what the characters were like. This is just an example of the legacy of the oral tradition remaining in Homer's work.\n\nTypically the bard would sing these songs over the course of a few days. You will notice the Iliad is 24 books long, with climactic moments in the 8th and 16th book (The Trojans pushing back, and the death of Patroclus) which would suggest the story was told over three days, so that people would be excited to return the next day, making the bard more money.\n\nNow *what does this mean?* There were likely many tales sung by bards before writing even existed. For these two tales to be chosen to be written down is significant in itself. Ancient writing took a long, they didn't have the printing press or any other machine to mass produce these works, so they must have been important for anyone to even bother writing them down. On top of this, the fact that they survived until today (or the Renaissance to be exact) is even more significant. \n\nIn short, a huge amount of the written works of the world were lost from the time these stories were first written (~760 B.C.) until today. So for us to have essentially complete editions of these works, on top of the fact that they wrote them down at all, is incredibly significant, and would indicate their popularity to the Greeks and the scholars who followed them (of every age). \n\nThis is my first post here, and a lot of this comes from my own knowledge through classes, I included a few sources but if you would like more let me know. \n\nEdits for grammar.\n\n-------\nSources:\nA summary of the original work: Parry, Adam (editor) (1971), The making of Homeric verse. The collected papers of Milman Parry, Oxford: Clarendon Press\n\nA more recent analysis of the Oral Tradition:\n_URL_0_\n\nAlso a former professor of mine was the son of Albert Lord, I took two classes from him, one on epics, and one on Tolkien.\n",
"The Homeric poems seem to have been composed in the early-to-mid-7th century BCE, ca. 670-650 in the case of the *Iliad*, but though the stories of the Trojan War and of Odysseus' return were popular throughout the Greek and Etruscan worlds from a very early date, the poems themselves seem to have had only limited dissemination for the first 100-150 years of their existence. From about 550-520 BCE onwards, they experienced a meteoric rise in popularity, and they have never lost that popularity since.\n\nWe first hear of Homer in a historical context in Sikyon, ca. 570 BCE, when the local king allegedly banned performances of Homer because his poetry praised his rivals the Argives. However, that story only makes sense if we understand it as talking about the lost *Thebaid*, not the two epics that have actually survived. An even more doubtful reference tells us that the 7th century BCE poet Kallinos attributed the *Thebaid* to Homer. These stories are the only references to Homer or to Homeric poetry that we can be confident of prior to 550 BCE: we have no evidence of anyone knowing the *Iliad* and *Odyssey* at all.^1\n\nAfter 550, everything changes. Previously, vase-paintings of Trojan War scenes used material from throughout the legend of the war; after 550 there is a sudden, very sharp increase in popularity of scenes relating to the *Iliad*, and by the early 400s it's possible to see direct influence from the *Iliad* in the pictorial tradition. Stesichoros, Herakleitos, the *Hymn to Apollo*, and Simonides making explicit references to Homer or \"the man from Chios\". Theagenes of Rhegion writes the first piece of scholarship on Homer, giving an allegorical interpretation of the gods. A fairly compelling argument has been made that the *Iliad* was first popularised at the Panathenaia of 523/522 BCE; the argument is conjectural in parts, but we do have good evidence that Homer wasn't performed in Syracuse until 504, so it's certainly not implausible. And finally, any kind of fixation of the Homeric epics in writing relies on writing having a particular cultural function, and Jesper Svenbro has shown from epigraphic evidence that it was only ca. 540 that written texts began to acquire the function of *reproducing* an utterance, as opposed to *being* an utterance (that is: earlier inscriptions refer to the inscribed object as \"I\", or address the reader as \"you\"; writing was supposed to be an utterance that made sense at the moment of reading, not an archive of an old utterance).\n\nWhat seems to have happened is that up to this point, the *Iliad* and *Odyssey* were transmitted orally in a poetic tradition on Chios, as the heritage of a group of poets there who were called (or who called themselves) the *Homeridai*, \"sons of Homer\". This appears to be why Simonides and the *Hymn to Apollo* treat \"Homer\" as Chian. The name \"Homer\" itself was a marker of a poetic heritage; whether or not a real man of that name had ever existed, that was the meaning it had for people of the 6th century BCE -- a label for a body of poetry linked by the affiliation of the poets who created it: the *Iliad* and *Odyssey*, but also the *Thebaid*, the *Epigonoi*, the *Hymn to Apollo*, the *Margites*, and other pieces. Similar heritage labels emerged elsewhere, under the names of \"Orpheus\", \"Mousaios\", \"Hesiod\", and possibly others (I suspect Sappho and Solon should also be regarded more as heritage labels than as historical individuals, even if those individuals actually existed).\n\nAfter 550-520, the *Iliad* and *Odyssey* were both treated as classics, memorised by the elite, recited at aristocratic parties, performed in major civic competitions, imitated and excerpted by other poets, quoted by philosophers, and studied by scholars. From 520 BCE up to the present, their status as the preeminent classics of Greek literature has been unchallenged. In western Europe they were much less read in the period ca. 300 CE-1500 CE, but before and after that date-range they have also reigned there as the key foundational works of Western literature.\n\n---\n\n**Note** \n^(1)There are several other pre-550 BCE references that have been *interpreted as* references to Homer, or as quotations, but since the nature of Homeric poetry and the mythical content of the poems is in every way traditional, it is more parsimonious to interpret these as cognate with Iliadic/Odyssean material, rather than derived from Iliadic/Odyssean material. These references are: (1) \"Nestor's cup\", ca. 730 BCE; (2) Tyrtaios fr. 10.21-30 West; (3) Alkman fr. 80 Page; (4) Mimnermos fr. 2.1-4, fr. 14.1-3; (5) Mousaios fr. 5 D-K; (6) Alkaios fr. 44 and fr. 395; (7) the Hesiodic *Shield* as a supposed imitation of *Iliad* 18; (8) knowledge of the *Iliad* attributed to Solon (Plutarch *Solon* 10, Strabo 9.1.10)."
]
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[
"http://www.reddit.com/r/AskHistorians/comments/1kldhj/did_the_ancient_greeks_view_homers_iliad_and/",
"http://www.reddit.com/r/AskHistorians/comments/1izjt7/how_influential_were_homers_works_the_iliad_and/",
"http://www.reddit.com/r/AskHistorians/comments/2exov4/how_well_known_would_the_stories_in_the_odyssey/",
"http://www.reddit.com/r/AskHistorians/comments/12nwt4/how_commonly_known_would_the_story_of_the_iliad/",
"http://www.reddit.com/r/AskHistorians/comments/xsa8l/are_the_iliadodyssey_and_the_epic_of_gilgamesh/",
"http://www.reddit.com/r/AskHistorians/comments/24ed54/were_stories_such_as_the_iliad_and_the_odyssey/"
],
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"http://www.yale.edu/heyzeus/spring2004/zeus_sarah_price.pdf"
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gsv7q | Could someone clear this whole thing up? (When smoking from a bowl made of aluminum, can aluminum enter the lungs?) | This is in reference to this [post](_URL_0_). | askscience | http://www.reddit.com/r/askscience/comments/gsv7q/could_someone_clear_this_whole_thing_up_when/ | {
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"This guy has been smoking too much and not taking enough science courses. The list of ignorant things is kind of long, and my patience for stoners in pretty short, so I'm going to keep this brief and to the point. (In case anyone decides to nitpick details.)\n\nA Butane lighter simply doesn't have the actual heat out put needed to melt aluminum. Even if it did, you would not be able to hold a piece of aluminum with your hand and melt the other end, it would burn you. There is more to melting metal than temperature. Oxidizing aluminum foil is not the same as melting it.\n\nI seriously doubt the guy died of aluminum poisoning, unless he ingested a significant about of aluminum from some other source. his lungs were shot from smoking weed, it's every bit as bad for your lungs are smoking cigarettes, probably worse because they are unfiltered typically. \n\nCommon antacids contain aluminum [Wiki](_URL_0_) if it was so poisonous we'd be seeing people die all the time and it would have been banned a while ago.\n\nEdit: Reading the linked thread makes me hope that a lot of those guys die before having children.\n\n",
"You don't have to melt the Al to get it into the lungs, you just have to mince it fine enough to get it suspended in the air. I can see this happening with heating Al foil, especially repeated heating. \n\nI don't know exactly how they are using it in the linked discussion, though, and I don't know the exact chemistry involved, so take that as you will.\n\nAlthough aluminum in your digestive tract isn't an issue at any sane dose, ANY particulate matter, especially metals, can really mess up your lungs. I'm not talking about vaporized aluminum (I actually think that would be less dangerous), I'm thinking more along the lines of a fine aluminum powder. \n\nThis would get down into the lungs and make your clearance system go nuts, eventually leading to COPD-like symptoms and possible brochiectasis. \n\nI doubt this would happen from a single exposure, or even multiple infrequent exposures. And it is certainly not specific to aluminum. But chronic regular exposure could cause serious problems, especially in people prone to COPD. And there is a mechanistic posibility of marijuana use increasing COPD risk over that of tobacco smoking at the same level. To my knowledge it has not been linked statistically, but the mechanism is there)."
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"http://www.reddit.com/r/trees/comments/gskqe/dont_die_too_young_a_friendly_reminder_never_to/"
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2xy8fa | how do floors get mopped, garbage cans get emptied, plumbing get repaired etc. in top secret areas? are there janitors with high level security clearance? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2xy8fa/eli5_how_do_floors_get_mopped_garbage_cans_get/ | {
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"Areas like that have \"clean desk\" policies where everything has to be secured in locked drawers when you are not at your desk. If it is somewhere with constant activities then the people there take their trash to somewhere outside the room where it gets collected.",
"Like at military facilities? Such maintenance would be carried out by low-ranking service members. In cases where equipment goes bad and you need a specialist (read: civilian contractor who only works on X equipment), usually they hire prior service-members who have gone into a relevant field and have secret or top secret clearances, and then those contractors are only allowed to go where their work requires them to be. Depending on the facility/base/wherever, they may be escorted some or all of the time.",
"The area is first cleared of all classified material. Documents are placed in safes with electronic locks. Equipment is moved to other classified areas. All workers are notified ahead of time that the area is under maintenance and not to discuss nor work on anything classified in the area during that time. A guard is placed to watch the open doors to ensure the only people going in and out are the intended service people. Once the job is done, the area can be secured again to resume classified work.\n\nAs for garbage cans, workers just leave them outside the area.",
"* yes, often they do have high clearance\n* when you are away from your desk, and classified material much be secured, so there is really nothing to see\n* workers are notified when a uncleared personnel enter the area, and are required to secure documents immediate"
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15fnu6 | if you are able to look at somebody's reflection, this person must also be able to look at yours. does this concept apply always? | Just like you are capable of looking at somebody's reflection, this person must also be able to look at yours.
However, is there an exception to this rule? Perhaps due to refraction, etc.? If so, how is it possible? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/15fnu6/if_you_are_able_to_look_at_somebodys_reflection/ | {
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"The way light bounces, this will always happen on a *flat* surface. If the surface is warped, skewed, or bent, the light will bounce back according to that angle.",
"if you can see their eyes, then they can see your eyes. It always *works* with cameras because the camera IS the eye.",
"If you put a camera in front of a mirror and watch someone's reflection through the camera feed, then you can see their reflection and they can't see yours.",
"If the other person is blind.",
"the light is bouncing from their reflection off the mirror into your eyes. this means the light bouncing from you is reflecting back at them too, as the mirror is _always_ reflecting light. \n\nthe exception to this rule is if you are in complete darkness, but the other person is in the light. then they cannot see you, but you can see them (as long as the light isn't bouncing off the mirror)"
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6meoid | what happens to clinically insane people after committing crimes that if a non-insane person did, they would receive the death penalty? | Also, where did these laws originate from? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/6meoid/eli5_what_happens_to_clinically_insane_people/ | {
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"Part of a crime is intent and knowledge of the likely outcome of one's actions.\n\nIf a person is \"not guilty by reason of insanity\" it means that durring that *specific* crime they did not know what they were doing, similar to how a person is not guilty of a crime if a crane unexpectedly breaks and it's load crushes someone.\n\nSimply *being* clinically insane is insufficient to get off the hook for a crime.",
"There's a concept in criminal law, that requires that the person understand what they did was wrong. This concept can be directly traced back to Roman legal codes (though like many Roman concepts, they borrowed it from a [Greek thinker](_URL_1_)). It's not true for certain type of crimes (crimes stemming from criminal negligence or strict liability crimes). \n\nIf someone is found not guilty for reason of insanity, they are usually confined to a mental health facility until they are declared sane. One of the most famous, successful [insanity defenses](_URL_0_.) was recently released from institutional confinement last year, after 30 years of institutional treatment. ",
"Clinically insane doesn't matter, you need to be *criminally* insane.\n\nCriminal insanity means you are so detached from reality you can't see that your action are wrong. If you attacked a snake person who was using mind control beams to steal your precious bodily fluids, cleverly disguised as your mailman, that would be criminal insanity.\n\nIf you were institutionalized because your severe OCD made it difficult for you to lead a normal life, murdering someone would still be a crime and you would face normal criminal penalties.",
"To expand on what others have said, *CRIMINAL* insanity is when you have such a lack of grip on reality that you cannot possibly understand you were committing a crime.\n\nAn example from The Law Of Superheroes, written by two Harvard lawyers who were comic book fans, showed how most versions of The Joker would be clinically insane, but WOULD be declared competent to stand trial. This would be due to the fact that most versions of The Joker have demonstrated premeditation of the crime, and spoke of the act in ways that demonstrated he knew it was a crime."
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6u3rr6 | Do doppelgängers have extremely similar DNA like siblings or twins do? Or do they appear unrelated when taking a DNA test? | askscience | https://www.reddit.com/r/askscience/comments/6u3rr6/do_doppelgängers_have_extremely_similar_dna_like/ | {
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"If you are asking whether people that look superficially the same as you would show up as related to you if they took a DNA test, then no. These types of genetic testing look primarily at so called junk DNA, the ~98% of you DNA that is not actively involved in how your body is created, so any similarities between people are due to either ancestry or coincidence. "
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5bltbq | how are there enough cows to supply the over 15k macdonalds and burger kings in u.s. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/5bltbq/eli5how_are_there_enough_cows_to_supply_the_over/ | {
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"First, a single cow produces an awful lot of hamburgers. A grown steer produces about 500 pounds of beef, which is 2000 quarter-pound hambugers.\n\nSecond, there are enormous herds of cattle on ranches in the rural parts of the US, which you generally don't see because they're not along highways, but the US is enormous and can easily hold them. The state of Texas alone has more than 11 million cattle, or 22 billion hambugers worth.",
"The average carcass weight was 475 in 1975. As of 2005 it was over 600 pounds. A Holstein female can weigh up to 1500 pounds. My father in law raises cows, have about 100 pounds in my freezer. The taste is more like a high end restaurant than store beef. ",
"Cheap beef is sourced from farms which use a feed lot system, rather than traditional grazing. In a traditional grazing system you might expect to have about one cow per acre.\n\nIn contrast, the stocking density in a feedlot is often well in excess of 100 cows per acre (and that *includes* the space requirement allocated for driving routes, feed stalls, waste mangagement, etc, so not just space for cows).\n\nTo be clear - many traditional farms use feed lot systems in the winter months when grazing can be difficult. The difference with intensive farming practices is that they use feedlot year-round.",
"Well, the answer to your question is very simple. So I'll just answer with a question: what do you do when you run out of something? You buy more, right? Well, same thing happens here. Demand creates a feedback loop where the more hamburgers you want, the more cows are raised for slaughter. \n\nIronically, these cows are significant contributors to global warming due to the methane they... exhaust.",
"My company makes a product out of collagen , I was amazed how many cows there are in the world. ",
"There are fields, /u/Hipposeverywhere, endless fields, where cattle are no longer born. They are grown.\n\nHere's a few pictures:\n\n_URL_1_\n\n_URL_0_",
"I lived in amarillo tx for a few years. Just outside the city Cows/steer outnumbered the population of the city like 2 to 3. \nAnd it smelled like it. \n\nThat isnt the smell of shit son, that is the smell of money.",
"You REALLY don't want to see the *factories* in Texas where cows are raised for cheap meat. You can smell their putrid odor from miles away (not kidding).",
"Do you realize how big the US is?",
"Not an answer to how many cows, but does answer some questions on where mcdonalds gets their beef _URL_0_",
"Not all of it is 100% beef\nSoy and other product are added into the patties heavily (unless marked 100% beef).",
"Not only are there an awful lot of cows, [they are one of the leading contributors to climate change](_URL_0_).",
"There are approximately 92 million cattle in the US today. Of which, about 30 million are beef cows (adult breeding females) and 9 million are dairy cows. The rest are essentially calves and bulls.\n\nBeef cattle: Obviously, beef cattle are selected, bred and raised specifically for their meat-producing traits. Ranchers want breeding cows that easily give birth to calves that can add muscle and fat quickly, convert feed efficiently and produce well-marbled and delicious beef. Therefore, they select breeds and purchase bulls/semen that have these characteristics. Most ranchers will spend a lifetime building a herd to their liking and thus typically keep the best heifers (females that have yet to give birth) born on their ranch for breeding. They buy new bulls every year or two OR they purchase semen and artificially inseminate their heifers/cows. This promotes genetic diversity and quality and prevents inbreeding in the herd. A beef cow will typically give birth to 10-12 calves in her lifetime. The bull calves born on a ranch are typically castrated (thereby becoming \"steers\") and are weaned from their mothers at about 8 months of age and then sent to a feedlot for \"finishing,\" usually with corn or some other grain. They will often be on grass with their mothers until that time and the cows will spend virtually their entire life outside on grass (sometimes supplemented with hay in the winter). The best heifers are kept and put in with the bulls at about 15 months of age to give birth at 24 months. The heifer calves that don't make the cut as breeding stock take the same path as their steer cohorts. After these \"feeder calves\" reach between 1100 and 1300 pounds, they are sent to the packing plant and become steaks, roasts, burgers, etc.\n\nBeef Terminology: Ranchers who own breeding cattle and raise baby beef calves have \"cow/calf\" operations. They own pastures and harvest hay to feed their critters and tend to be relatively small. An average cow/calf operation has only 40 cows and a large one might have 400 cows, but it's too land- and labor-intensive to get much larger. Ranchers then sell their calves to people who run feedlots, called \"feeders.\" A feedlot might have several hundred to several hundred thousand animals. These guys, in turn, sell to folks who run slaughterhouses: \"packers.\" These are usually completely separate entities.\n\nDairy Cattle: These bovine are bred for their ability to produce milk. Some breeds are renowned for the amount they produce while others tend to have more fat in their milk which is valuable for butter, cream, etc. When a dairy cow gives birth, the calf is taken away from her within 3 days or so and is fed by humans -- usually a manufactured powdered milk. The cow is milked 2 or 3 times per day, every day, until she goes dry after several months. She is then bred again. The cow's milk goes to the dairy. Many dairy heifer calves are kept to become milk cows but the rest, along with the steer calves (they also get castrated), become veal or are sold at approximately 6 months of age and also go to a feedlot to be fed up to 1000 pounds or more. Because these calves are not bred for their meat traits, their roasts and steaks are a lower quality than muscle cuts from beef cattle and the entire animal is often ground up for hamburger. Dairy cows usually have 4 or 5 calves and live to be about 6 or 7 years of age and many (although certainly not all) are kept in barns during their lifetimes and do not get to go outside and graze. Dairy farms have grown exponentially in size over the past 30 years. Most are now milk at least several hundred cows and many have several thousand.\n\nOld bulls and beef and dairy cows do not die of old age. They have value -- also mostly as ground beef -- and are sent to feeders/packers when they can no longer breed. We slaughtered about 29 million head of cattle in the US in 2015 and many of them weren't young, fattened beef cattle full of restaurant-quality steaks and roasts. This is why we have so much ground product and why a good steak costs so much more than 80/20 ground beef and how we're able to keep the fast-food restaurants supplied. The structure of the industry also explains why you see huge feedlots of cattle in Texas, Nebraska and Kansas. It's not because all cows now live in feedlots but because that's the system we've developed in order to efficiently fatten certain cattle in a short window of time and meet consumers' taste demands. \n\nSource: Grew up on a beef cattle ranch, father and brother-in-law still ranch."
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9uqghw | why do my hands feel weak after i watch doctors taking blood. | It doesn't have to be blood, basically whenever I see someone injecting needle my hands suddenly feel weak and weird. I can't even clench the fist as good as usual. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/9uqghw/eli5_why_do_my_hands_feel_weak_after_i_watch/ | {
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"Likely because some part of the process makes you anxious and you experience a mini fight-or-flight reaction of blood being drained from your extremities to be pumped into things your body deems more important in the moment. Possibly resulting in your hands even becoming totally numb. \n\nSource: Am deathly afraid of needles and experienced what I described last trip to the doctor. "
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arg2iy | if black absorbs all colors on the visible spectrum, then how are there glossy black finishes that reflect light | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/arg2iy/eli5_if_black_absorbs_all_colors_on_the_visible/ | {
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"There are more ways light interacts with a surface than by absorption. Reflection is a different mechanic where the light is bounced off the surface based mostly on the smoothness of the surface. This is only a surface effect.\n\nDifferent materials will have different reflectivity, the tendency for a material to reflect light.\n\nThere is also emissivity which is the tendency for a material to produce light from it's heat or absorbed light. A black material is as perfect an emitter as it is an absorber. Though it's emitted light is directly related to the temperature of the object, or the energy lost by absorbtion. Emitted light is usually in the infrared range, invisible to us but felt as heat.",
"Pure black would absorb all colours, however pure black doesn't exist. Glossy black reflects some of the light.\n\nThere is the nanotubes based black called Vantablack which reflects only 0.04% of the light. And that is the blackest black we have at this moment: People who see it for the first time go from \"There is an empty hole in this\".",
"I think it has more to do with how the surface interacts with light at. More microscopic level. When you have a glossy finish, the light hits and is generally reflected straight outwards, when you have a stain finish, the surface in more 'bumpy' which makes the light more prone to reflecting into another interaction with the material.",
"Ideal black paint would absorb all light. Regular black paint are not ideal and will reflect light black, it is easy to see the it is the case by pointing a flashlight on the object if you can see a difference in brightness then some light is reflected back.\n\nThere is not material that absorb all light the best is [Vantablack](_URL_0_) that absorb 99.96% of all visible light and regular object that you thing is black absorb a lot less light then that.\n\nWhite paint and a regular mirror reflect only 80-90% of all light that hits them so you might reflect a couple of percent of the light and we consider it black. For a mirror the aluminium coating reflect 90% ad a bit more is absorbed by the glass.\n\n\nGlossy is the amount of light that is reflected by specular reflection, that is when all light that is reflected bounce in one direction like a mirror. A matte/flat paint reflect light in all direction ie diffuse reflection. \n\nSo matte white paint and a mirror reflect the same amount of light. A mirror has almost only specular reflection and matte paint almost only diffuse reflection. So the glossy matte is how it reflect light not the amount.\n\n",
"A perfect black body would not be visible to the naked eye if it absorbed all colors on the visible spectrum. Black holes aren't even perfect black bodies since they reflect light, albeit an extremely small amount of it. The color black that we can see reflects a small amount of light, which makes it possible for us to view it."
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11kabv | Can chivalry in the Middle ages be seen as an attempt to rein in the violence of the warrior classes? | I saw this mentioned in a thread on the crusades (in relation to the crusades giving the pope the advantage of sending much of the violent warrior class away). Is this backable?
THANKS EVERYONE! | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/11kabv/can_chivalry_in_the_middle_ages_be_seen_as_an/ | {
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"That sort of thing is difficult to measure.\n\nChivalry may have more of a literary basis. The chivalric code appears in stories like Sir Gawain and the Green Knight or in El Cid, but in actual battle field scenarios, finding evidence of chivalry can prove more difficult. The simple fact is that in medieval warfare, peasants and noncombatants were almost always caught up in the fighting. In sieges, if peasants weren't kept out to begin with, they could expect no quarter. Women would be raped and murdered. In warfare, peasants could be expected to be robbed of their livestock or wealth (such as it was). Nobles somehow captured in battle could potentially be imprisoned and ransomed, sometimes.\n\nAnd we're talking Christians against Christians at this point. The situation gets even more dire when one considers Christian interaction with Jews, Muslims, or pagans.\n\nChivalry could also motivate toward violence. Chivalric competition among French knights leading up to the Battle of Agincourt propelled them to outdo one another in the field, to commit even more lunatic acts (being a blind man and riding into battle, for instance) in the name of courage and, yes, chivalry.\n\nWas chivalry initially intended to prevent violence, somehow? No, probably not. And if it was, it didn't do a very good job of it.\n\nHope this helped.",
"A partial answer: a part of the idea of 'chivalry' in western Europe came from the [Peace and Truce of God](_URL_0_) a movement traced to the tenth century that resulted in quite a few proclamations by both religious and secular leaders. It was an attempt to govern internal violence, setting aside days of the year on which war could not be fought and people against which violence could not be committed. ",
"Much of the chivalric code, isn't particularly chivalrous in the modern sense. For example, while the lady of your liege lord was to be treated with deference and respect, the lady of an enemy lord could expect to be raped and murdered if captured.\n\nThe code legitimised much of the violence of the warrior class rather than constraining it.",
"See my response to BarbarianKing for some critiques of his answer.\n\n It is fundamentally important to remember how complicated a) people and b) social systems can be. The Middle Ages is not a neat or a clean period (frankly none is). \n\nChivalry is, at its heart, a system of conduct meant to regulate interactions between the elites. It simultaneously glorifies the martial aspects which are fundamental to the aristocrats of the period and sets limits and strictures on them.\n\nWhere things get tricky is that there is no *set* rule-book, no system of formal arbitration and, frankly, no consensus. This is not a system that a person or a group of people set down logically. It is an organic system that evolves over time, responding to and shaping the ways in which people think and act. \n \nWhat we can see, however, is that the 10th and 11th centuries are a period where violence is largely unregulated in Europe, and there is *intense* anxiety about it. Whether the actual levels of violence are higher is a debate that is still raging among medievalists. But either way *feelings* about violence (as expressed in charters, sermons, literature, history etc.) all indicate how worrisome it was.\n\nWe see, as the 11th century moves on and the 12th begins the development of a whole series of social constructs and systems which in many different ways work to allay that anxiety, either practically or mentally. Both the crusades and chivalry function as release valves and channels for aristocratic violence.\n\nalfonsoelsabio mentioned the Peace and Truce of God below (which I've also mentioned elsewhere). This is another, earlier, example of attempts to regulate and channel violence. So too are attempts to end feud and curb private justice which are so prevalent in the judicial and governmental reforms of monarchies n the High Middle Ages.\n\nBut what you have to remember is that none of these actions are being undertaken with a clear, conscious rational. They are responses to societal pressures and concerns. No one is sitting in a board room saying 'there is too much violence, how can we mitigate it?'.\n\nFinally I should make it clear that there is literally nothing weird or contradictory about a system or a culture that simultaneously extols violence and peace. We live in one now. We market video games that let you play the soldier while simultaneously suspending children for playing with pretend guns in the school yard. Societies are not neat nor are they one tone.\n\n"
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3r3tvw | what is going through my cat's head when he runs back and forth seemingly aimlessly? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/3r3tvw/eli5_what_is_going_through_my_cats_head_when_he/ | {
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"Although there are a bunch of factors to consider, (sterilization, age, etc) if I had to make a personal guess, I'd say he has a natural instinct to prowl and hunt like in the wild and since he can't exactly do those things, he just aimlessly runs."
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710po8 | In physics, why is the formula to calculate force F=ma instead of F=mv (mass x velocity)? | For example, if a car that weighs 2 kilograms his traveling at a constant speed of 31 meters a second as the car hits you. It would give you a fair amount of force right?
But the formula states that since the car is not accelerating and is at a constant speed, a=0, since 2,000 x 0 = 0 the formula says that the car hits you with a force of 0 newtons (which I don't think is accurate)
Even if the car started at 0 m/s and started to accelerate at 2m/s/s wouldn't the calculations still be wrong and have an incorrect amount of force calculated?
| askscience | https://www.reddit.com/r/askscience/comments/710po8/in_physics_why_is_the_formula_to_calculate_force/ | {
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"The problem is that you are not calculating an impact force correctly. The equation **F** = m**a** tells you the net force on an object. But the equation does not tell you directly the impact force of one object on another when they crash.\n\nFor instance, if an object of mass *M* traveling at speed *V* just before impact crashes into a rigid wall and comes to rest over a time period *T*, then Newton's second law tells you that the average impact force felt by the object was F = MV/T because its average acceleration was just V/T. So, indeed, the impact force increases with impact velocity, as expected.",
" > instead of F=mv (mass x velocity)?\n\nMass times the velocity is the momentum. It's also a useful quantity. \n\n > But the formula states that since the car is not accelerating and is at a constant speed, a=0, since 2,000 x 0 = 0 the formula says that the car hits you with a force of 0 newtons (which I don't think is accurate)\n\nThink about it this way, if you suddenly go from 60 MPH down to 0 MPH due to your car smashing into a wall what does that imply about the acceleration? \n\nThe problem with your thinking here is that the equation a = 0 only holds until the car actually crashes, once the crash happens you need a different equation. F=ma is true in both cases.\n",
"The force you feel as a result of a car hitting you is based on your acceleration the moments after the collision, not the car's acceleration. There is an equal and opposite force that actually slows the car down (not by much, because the car has much greater mass and to someone sitting in the car it feels like a speed bump). \n\nForces are much easier to understand when they are long duration forces, like gravity, or a rocket engine. For collisions it's easier to think in terms of kinetic energy.",
"Just to clarify, your example about the car constantly moving at 31 meters a second and that car crashing at you are two different situation.\n\nWith the car travelling at constant speed of 31m/s, the notion that the force is zero is correct (assuming ideal frictionless, lossless car). Because there's no *force* imparted upon the car at the moment, there's no *change* in the car's speed.\n\nWhen the car is crashing at you, the force you feel is proportional to the deceleration caused by the impact. Usually the deceleration is quite fast, so the force is quite high too. Modern car construction, like deformable bumper or bonnet are designed to deform upon impact, cushioning the impact force, while also somewhat lessening the deceleration imparted upon your body."
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6b9jzz | What stopped Nixon's push for Universal Healthcare? | Was it true universal healthcare? Was it a single payer system or something with private industry? Why was it politically stopped? | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/6b9jzz/what_stopped_nixons_push_for_universal_healthcare/ | {
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"Politics, plain and simple.\n\nUntil the end of his life Sen. Edward Kennedy said his greatest regret during his political career was turning down President Nixon's deal on healthcare.\n\n[This column] (_URL_1_) from 2009 and [this one] (_URL_0_) from 2012 do a good job explaining the plan and the dynamics of the 1970s that caused it to fail.\n\nThe plan was not true universal healthcare, but it would have been a step towards universal coverage and possibly single payer.\n\nWhat failure to make a deal came down to was interest groups lobbying Congress and throwing their electoral weight around. Once elections were on the line, elected officials chose not to risk those groups support next election.\n\nI think those two columns only touch on, but do not really emphasize Ted Kennedy's prominence during these years. JFK was assassinated in 1963 and RFK in 1968, Ted Kennedy was the heir to the Kennedy political dynasty and heir to the party's Presidential nomination. Despite not being his party's official Senate leader, as the favorite for the nomination in 1972 he was in many ways the de facto party leader.\n\nIf Ted Kennedy agreed to a deal he would have brought with him Democratic votes in the House and Senate. Once Kennedy turned down the deal due to lack of union support there was nobody in a position to pickup negotiations. Unions made up a significant portion of Democratic voters and donors and no Democrat around 1970 would want to put that at risk, especially after it caused Kennedy to step away from the deal."
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cy4svt | how is liquid nitrogen kept cold? can it be kept in a bottle for a long period and still be cold? | I understand the relation beetwen pressure, temperature and volume, so if I manage to keep liquid nitrogen under pressure for 20 years it will still be cold? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/cy4svt/eli5_how_is_liquid_nitrogen_kept_cold_can_it_be/ | {
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"LN2 is stored in dewar's for smaller amounts or in cryogenic tanks for larger quantities. Dewar's are just high efficiency thermos tanks usually with a vented lid. Why the vent? Because no thermos is perfect at retaining temperature, so as temp goes up, the volume increases and there is a phase change from liquid to gas. \nThe cryo tanks usually have a mechanism for keeping the tanks chilled so as to keep the LN in a steady state.\n\nEdit: typo",
"Ok, so if you have a bit of water, and you blow on it, it gets cold. That's basically because you're encouraging it to evaporate. It's evaporation (the transition from liquid to gas) that makes it cold.\n\nIf you have liquid nitrogen in an open container at Sea level pressure, it will also evaporate, but at a much higher rate than water does. It will boil in that container, and that rapid evaporation is what makes liquid nitrogen cold under those conditions.\n\nBut if you have liquid nitrogen in a sealed container at room temperature, and at Sea level pressure when you seal it up, some of the liquid will evaporate inside that container. Since the gas has nowhere to escape, the pressure will build up. The container will get cold while this is happening.\n\nEventually, the pressure in the container will be so great that the nitrogen will reach an equilibrium between gas and liquid. For every molecule of nitrogen that escaped into the gas phase, one molecule will go from had to liquid phase.\n\nThe container will gradually warm to room temperature, even though there is liquid nitrogen inside it. If you put the container on a heater, the liquid nitrogen will boil, and the pressure in the container will increase, and the nitrogen will adjust to the new, warm temperature.\n\nThe container will largely stay at it's surrounding temperature, as long as the gas does not escape, so you cannot actually keep such a container cold forever. The number of nitrogen molecules, the volume of the container the pressure, and the temperature are in a constant balance that is largely described by the Ideal Gas Law\n\nPV = nRT\n\nPressure x Volume = (number of molecules) x (Ideal Gas Constant) x Temperature"
]
} | []
| []
| [
[],
[]
]
|
|
7iwdqw | how does left-cardiac hypertrophy lead to cardiac arrhythmias? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/7iwdqw/eli5_how_does_leftcardiac_hypertrophy_lead_to/ | {
"a_id": [
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"text": [
"With left-sided hypertrophic cardiomyopathy, the left ventricle is very muscular and that leaves little room for blood to fill up in it between beats. As a result, you can get blood backing up into the left atrium. This stretching can cause electrical signals to get \"messed up\" (simple way to put it), resulting in the heart doing weird stuff as it tries to keep up with the blood flowing into it.\n\nThere's also the issue of that super muscular chamber contracting really hard, which can throw off the normal rhythm. ",
"It's less about size and blood perfusion than \"disarray.\" Those who develop what you could call an \"induced hypertrophy\" (high blood pressure or tight valves leading muscle growth on response to resistance) aren't at the same risk as someone with Hypertrophic obstructive cardiomyopathy (HOCM, 'the young athlete killer'). \n\nThe cells in the heart of those with a primary hypertrophic cardiomyopathy (like HOCM) don't grow right, they align poorly, and they don't conduct right electrically. Those messy electrical pathways are where trouble happens... Extra signals, stacked signals, etc can lead to arrhythmias (total chaos). \n\nThat messy muscle cell growth can also happen somewhat in really bad heart disease from valves or high blood pressure, like I mentioned, but that's not generally the issue that leads those folks to medical attention (or death), but it does happen occasionally. \n\nDisclaimer: this is a major simplification \n(source: I'm an internist) "
]
} | []
| []
| [
[],
[]
]
|
||
4ubixe | would there be any temperature difference if the speed of the light were slower? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/4ubixe/eli5_would_there_be_any_temperature_difference_if/ | {
"a_id": [
"d5oe18d"
],
"score": [
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"text": [
"I'm not sure I can ELI5 this, but i'll just try and explain it anyway. I'm not really sure what the best answer, but my best guess is that it depends on what other physical constants changed. Assuming that everything was held constant and you just halve c, going with the [plank einstein relation](_URL_0_) E=c/wavelength, then as c decreases, E decreases, and so temperature would go down.\n \nAnother way to look at this is that since frequency is inversely proportional to wavelength multiplied by c as a constant, so as c goes down, the frequency at a particular wavelength of light would be lower. If the photo frequency is lower, then things are moving around slower. Slower moving is less energy, is lower temperature. \n\nHowever, it'd also say it probably wouldn't *feel* colder, because the whole system would have adjusted down, including melting/boiling points, etc.\n\n"
]
} | []
| []
| [
[
"https://en.wikipedia.org/wiki/Planck%E2%80%93Einstein_relation"
]
]
|
||
1a6p6i | why are x-rays emitted through high powered lights, and just how dangerous could it be with prolonged exposure? | Me and my buddy found a RGB stage light in the garbage today and proceeded to take it apart unfortunately we did not read the warning labels until afterwards and found some very unsettling things: (_URL_1_)
(_URL_3_)
We have since then discarded it but the question remains how does this thing emit x-rays and how dangerous was it? additional photos:
(_URL_5_)
(_URL_2_)
(_URL_0_)
(_URL_4_)
| askscience | http://www.reddit.com/r/askscience/comments/1a6p6i/why_are_xrays_emitted_through_high_powered_lights/ | {
"a_id": [
"c8um12i",
"c8uvcs2"
],
"score": [
5,
2
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"text": [
"Those aren't actually stage lights; they're the CRT picture tubes from a [rear projection TV](_URL_0_). \n\nCRTs work by accelerating a beam of electrons in a vacuum tube to high energy, and letting the beam hit the phosphor-coated inner surface of the screen. Some of the energy excites atoms in the phosphorecent coating, and is released as light. But the electrons can also hit metal components inside the tube, releasing X-rays. Normally this isn't a concern, because the amount of radiation is small, and the front surface of the screen is made of glass that contains lead to absorb a lot of it.\n\nIt's exceedingly unlikely that there was anything radioactive in those tubes. The warning is there because radiation can be produced when they're operating at high voltage.",
"In answer to your question about how dangerous they could be, it depends on exactly how much X-ray radiation they would be giving off.\n\nThe world average for background radiation is 2.40 mSv a year from natural causes. A full body CT scan [X-ray radiation] would equate to 10 to 30 mSv (different websites seem to differ on this) in about 30 seconds, so worst case scenario there would be 1mSv/s. A fatal dose has been reported at [4.5-6 Sv](_URL_0_)\nas well as 21Sv.\n\n1mSv/s doesn't sound like much, but then that's just under half (41%) of the average natural background radiation per year, in a second. \n\nI'm only taking the worst case scenarios here though, the actual amount you'd receive if you was using the lights normally (though without the X-ray shielding for God knows what reason) at a distance that would be reasonable for a stage light (lets say it's 4m directly above you) you'd be receiving 1/16th the radiation than you would if it was a metre away. But in any case, prolonged exposure to just about any ionising radiation is dangerous."
]
} | []
| [
"http://i.imgur.com/DufN7zT.jpg",
"http://i.imgur.com/xMq8BLB.jpg",
"http://i.imgur.com/VBlwOEA.jpg?1",
"http://i.imgur.com/KgH2gUS.jpg",
"http://i.imgur.com/rDB0oQS.jpg",
"http://i.imgur.com/0dPjcmZ.jpg"
]
| [
[
"http://www.bigscreenparts.com/servlet/the-8467/RCA-P61310-Blue-CRT/Detail.html"
],
[
"http://en.wikipedia.org/wiki/Sievert#Dose_examples_2"
]
]
|
|
1p0bea | what process has happened over the years that makes things i found as a child hilarious to me then but now not finding them as humorous. | I feel I haven't changed much since I was a child. I just don't understand why I don't laugh like I used to at silly cartoons or rude jokes etc. | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1p0bea/eli5_what_process_has_happened_over_the_years/ | {
"a_id": [
"ccxftg9"
],
"score": [
2
],
"text": [
"You've developed more sophisticated tastes. Maybe not much more sophisticated, but still, at least a little. You've seen things that are far funnier than simple rude jokes or silly cartoons, and you've also seen so many rude jokes that the idea has gotten old."
]
} | []
| []
| [
[]
]
|
|
1ptbqx | How much air do various plants need to live relative to humans? | My 4 year old asked me this yesterday and I had no idea what to tell him. | askscience | http://www.reddit.com/r/askscience/comments/1ptbqx/how_much_air_do_various_plants_need_to_live/ | {
"a_id": [
"cd63ejx"
],
"score": [
3
],
"text": [
"The short answer is very little. You can keep a [plant in a glass jar]( _URL_0_) forever.\n\nIn principle a plant could run out of CO2, but in practice a plant will survive indefinitely in a sealed jar with a bit of soil because bacteria and nematodes tend to breathe in the O2 and exhale CO2. Plants also like to have oxygen so they can use stored sugars for energy at night, but in a jar they tend to supply themselves.\n\nThis works best with a jar that closes tightly filled with humidity-tolerant weedy plants that do not get very big like small ferns, dollarweed and mosses. If you use wild plants you tend to get some volunteer algae as well, and cyanobacteria (the green slime) can fix nitrogen from the air if they want to. Earth-in-a-jar is a fun little experiment. Just leave it in a windowsill."
]
} | []
| []
| [
[
"http://wcmastergardener.org/2013/02/24/53-year-old-terrarium/"
]
]
|
|
5d6juj | What were the average prices of firearms in the 1890 era american west? | I have a project I'm working on and can't find much readily avaliable. | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/5d6juj/what_were_the_average_prices_of_firearms_in_the/ | {
"a_id": [
"da2920r",
"da2ceih"
],
"score": [
12,
4
],
"text": [
"I would suggest finding a period Sears Roebuck catalogue. Sears Roebuck was the Amazon of its day, and sold everything from clothing to medicines to firearms by mail-order.",
"This is something that should be simple but incredibly difficult. Store records and sales logs are one of the more common preserved records in local historical society archives. Long-operating stores usually kept records of what they bought or sold, but afaik, there's no central database of these. You'd have to do a lot of footwork to dig through primary sources and construct a database. "
]
} | []
| []
| [
[],
[]
]
|
|
31o4s8 | hpv -- so there's an std that basically everyone has and it's benign except when it isn't? | I've heard so many different things about HPV -- from doctors, the CDC, and peers -- that I have absolutely no clue what the deal is. A good friend just had an abnormal pap smear and one doctor told her she couldn't have sex for a year and then another said she could because everyone had HPV already. I'm obviously hearing this second-hand, but wut? When I've talked to my own doctors, they've said similar things: there's no test besides the pap smear and I shouldn't worry anyways because non-cancerous HPV isn't a big deal because "it's so common" and "the body fights it off naturally." But then I have a a couple of friends with scary things like warts and pre-cancerous growths, so uhhh, that's not good.
So from what I've gathered, it seems like HPV is actually many different viruses. Some of them the body deals with naturally and it's NBD. But sometimes it's totally a BD because it gives you warts or cancer.
For some reason, we call all of them "HPV," and everyone has it. It's like the common cold of sex or something? And there's nothing you can do about it except condoms a little bit help, but not all the way?
TL;DR: Are millions of people crawling with STI viruses? Is that a problem? Why do some strains cause warts in some people but other times the strain doesn't do anything? Should I be worried about HPV? Or is it the common cold of STIs? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/31o4s8/eli5_hpv_so_theres_an_std_that_basically_everyone/ | {
"a_id": [
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"score": [
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"text": [
"Everyone is crawling with bacteria and viruses all the time. Having benign bacteria all over helps keep pathogenic ones away. Even different strains of the same bacteria/virus can behave quite differently.\n\nHPV infection is very common, so yes, it pretty much *is* the common cold of STDs. you can get it, fight it off, and get it again later. You can get it and have zero symptoms. You can get it and get cancer.\n\nHere are the facts on HPV, presented is a pretty easy-to-read format _URL_0_",
"I don't want to tell you whether or not to worry about HPV, but here's what I know about it. There are several different strains. Some of them cause warts, some of them don't. The ones that don't cause warts can sometimes turn cells cancerous, but generally don't have any other noticeable side effects. There's a vaccine that protects against the most common cancer-causing strains.\n\nA lot of people have HPV and most don't know it. Unless you have warts, or an abnormal pap smear, or get cancer from it there's not really a way to know whether or not you have it. In fact, there's not even a test for men to tell whether or not they have it (other than the \"see if you have a wart\" test).\n\nSo the strains that cause warts and the strains that cause cancer are generally separate. Men are rarely directly affected by strains that cause cancer. I think if a man gets it anally then the cancer becomes a bigger deal, but I’m not positive. Women who have strains that cause cancers sometimes get abnormal precancerous cells that show up on a pap smear. These cells may become cancer or they may not turn into anything. I don’t really know more beyond that and am not a doctor so I’m hesitant to speculate. \n\nSo to sum it up: A lot of people have HPV. A lot of those people don’t know they have it because they don’t show any symptoms and there are no tests for it. HPV generally only does two things: give you warts and/or cancer. If you’re aguy who doesn’t have sex with other men then the cancer probably isn’t a big concern. If you’re a woman, make sure to get regular pap smears and if one of them is abnormal see what your doctor says about it. If your doctor tells you something that sounds crazy like “you can’t have sex for a year” consider getting a second opinion."
]
} | []
| []
| [
[
"http://www.cdc.gov/std/hpv/stdfact-hpv.htm"
],
[]
]
|
|
5mgnr7 | why did the dea decide to make cbd a schedule 1 narcotic? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/5mgnr7/eli5_why_did_the_dea_decide_to_make_cbd_a/ | {
"a_id": [
"dc3gjbk"
],
"score": [
2
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"text": [
"Because there is a long history of pharmaceutical companies lobbying to have anything that might take some of their money made illegal. CBD oil is making headlines and deserves to be researched. By lobbying to have it made schedule I, there will be little to no research done in the U.S. ensuring that we will have to buy pharma products."
]
} | []
| []
| [
[]
]
|
||
hwlzm | A (probably) dumb question about dimensions... | I was just thinking: if we can represent a 3D space on a flat 2D surface, could we have a model in 3D of something that is really "4D"(like, let's say, a function)? | askscience | http://www.reddit.com/r/askscience/comments/hwlzm/a_probably_dumb_question_about_dimensions/ | {
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"text": [
"Absolutely. The [Klein bottle](_URL_0_) is one such example.",
"I did some googleing and found this for you, kinda lengthy but it looks like it has the potential to answer your questions\n\n_URL_0_\n",
"Yes, but it might not be so useful. Mapping 3D onto 2D usually provides a useful depiction since we are used to seeing a 3D world in 2D (our eyes really see a 2D image of the world).\n\nBut mapping 4D into 3D isn't very intuitive in many cases. Especially since that image will eventually be interpreted by us as being 2D (either when you see a picture of it, or if you stand in front of a 3D representation of the object).",
"[Carl Sagan explains 4th Dimension](_URL_0_)",
"Yes. The picture you see [here](_URL_0_) is of a 3D model of a 4D object called a tesseract, a 4D hypercube. Just like when going from 3D - > 2D a dimension is 'flattened', the same thing happens when going 4D - > 3D.\n\nThe added wrinkle here is that you're looking at a 2D representation of a 3D model of a 4D object."
]
} | []
| []
| [
[
"http://en.wikipedia.org/wiki/Klein_bottle"
],
[
"http://steve.hollasch.net/thesis/chapter4.html"
],
[],
[
"http://www.youtube.com/watch?v=UnURElCzGc0"
],
[
"http://en.wikipedia.org/wiki/Tesseract"
]
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|
|
2svhly | Historians, can you help me identify this money found in my granddad's WWII warchest? | [***Click for the Imgur album***](_URL_0_)
My granddad's war chest has a number of interesting items. I'll be posting them at a later time, probably to /r/historyporn. I'm curious as to the provenance and identity of some of these coins, though - any idea as to what they are and whether they are significant? I can post HD versions if you want. | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/2svhly/historians_can_you_help_me_identify_this_money/ | {
"a_id": [
"cnt942l"
],
"score": [
2
],
"text": [
"These are some interesting but commonly found banknotes.\n\nFrom top to bottom, left to right:\n\n10 000 German Mark, 1920's Weimar Republic/Germany.\n\n1 Pound - Japanese Occupation Currency for Oceania.\n\n10 Pesos - Japanese Occupation Currency for the Philippines.\n\n5 Pesos - Japanese Occupation Currency for the Philippines.\n\n1/2 Schilling - Japanese Occupation Currency for Oceania.\n\n5 French Francs - Wartime issue.\n\n1 Peso - Japanese Occupation Currency for the Philippines.\n\n10 Francs - Allied Military Currency.\n\n2 Francs - Allied Military Currency."
]
} | []
| [
"http://imgur.com/gallery/7RK1z/new"
]
| [
[]
]
|
|
32km16 | When the Germans were attacking Russia, and winter began, why didnt the Germans simply not take Russian clothing available on site? | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/32km16/when_the_germans_were_attacking_russia_and_winter/ | {
"a_id": [
"cqc5318"
],
"score": [
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"text": [
"The Soviets implemented a \"scorched earth\" policy designed to deprive the occupying Germans of anything and everything they might use to sustain themselves. This included burning down all usable buildings and their contents, killing any livestock that could not be brought east, poisoning wells and food, destroying machinery, burning oil fields and crops, ect. From what I understand although the Germans were not properly clothed for winter, once this problem became strikingly apparent this was attempted to be remedied by salvaging Russian clothes like you said, military issued winter wear, but also through clothing drives back home, where German families would send winter clothes and blankets to those deployed. However and getting back to \"scorched earth\", no matter how many pairs of socks or coats you have you need more then that to survive a long Russian winter of living, traveling, and fighting outside. You need shelter, downtime to rest (sweating can kill you), warm food, dry clothes to change into (harder to salvage), oils to keep your weapons and machines from seizing up in the cold (as well as spare parts), and most importantly fuel. This last bit was most scarce, with Panzer divisions and units of mechanized infantry running out of fuel throughout the campaign, and a reason why it was imperative for the Germans to strike south and capture the Baku oilfields in the Caucuses. This obviously did not happen, as the advance was stopped at Stalingrad.\n\nWhile it might have been theoretically possible to supply the troops with all these necessities, the Germans treated occupied populations as sub-humans. This deprived them of potential assistance (Soviet occupied people like the Ukrainians initially welcomed the Germans as liberators, but soon turned against them for obvious reasons) and created (along with the rapid German advance that left behind many Red Army units) partisan resistance that harried the rear and made supply, rest, and downtime from the front, very difficult. "
]
} | []
| []
| [
[]
]
|
||
cc5gl6 | What did Thomas Jefferson think of the Haitian Revolution? | A lot is said about what Jefferson thought about the French Revolution but what did he think about the ideas of the Hatian Revolution? Did he ignore the ideas presented? Did he respect the people revolting or the counter revolutionaries? Did he not really know much about it? And what did he advise the French do? | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/cc5gl6/what_did_thomas_jefferson_think_of_the_haitian/ | {
"a_id": [
"etlkols",
"etlpcd2"
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"text": [
"In Thomas Jefferson's letter to Lafayette in 1791, he wrote about the American, French, and Haitian revolutions. He praised the French for \"exterminating the monster aristocracy, & pulling out the teeth & fangs of it’s associate monarchy.\" However it is clear that he does not see the plight of the Haitians in the same light:\n\n > what are you doing for your colonies? they will be lost if\nnot more effectually succoured. indeed no future efforts you can make will ever be able to reduce the blacks. all that can be done in my opinion will be to compound with them as has been done formerly in Jamaica. we have been less zealous in aiding them, lest your government should feel their restoration, and their connection with you, as you do yourselves.\n\n[Source](_URL_0_)\n\nHere Jefferson speaks of the need for the French to placate and control the Haitians. He alludes to the peace treaties of the Jamaican First Maroon War, where the British offered a level of self governance to the rebelling slaves.\n\nAs president, Jefferson attempted to economically isolate the new, black-led Haitian government. This was in part an attempt to discourage similar rebellions in the American South, and calm the fears of slave-owners. (Jefferson and the Nonrecognition of Haiti, Matthewson)",
"I'm not a specialist in either American history, or Haitian History, but I've read [this](_URL_0_) book on the subject, called *Le Spectre de la Révolution Noire: L'impact de la Révolution Haitiene dans le monde atlantique* by Alejandro Gomez. The focus of this book is to address the répercussions of the Haitian revolution in the Caribbean; mainly in southern United States, Cuba, Venezuela and Jamaica. These repercussions varies from the initials notices of the revolution, to the creation of a significance on the revolution, to the usage of the revolution on political debate.\n\nWell, firstly, what are the main ideas, in the class that Jefferson belongs, about the revolution that I can give to guide you? Those are 3: The fear of revolutionary ideas (Jacobins); Racism ; and combining the two, the fear of the black Jacobins to bring violence to the beloved colonies. On the last subject, there was fear of uprising of black slaves on American colonies even before the haitian revolution, the revolution only made it worse.\n\nNow, to your question, the author uses some Thomas Jefferson letters as documents for his book on the southern United States, and that is what I can answer. He mainly saw it as a consequence to the most radical ideas of the French revolution, and said ideas would come like wind to America. Also, he hoped that it's passage on the USA wouldn't be violent. Because that's his view on the Haitian revolution, **violence**. He thought that the revolution had a bad interpretation on the rights of men, in a violent way.\n\nHe also thought that blacks and whites couldn't live together due to the prejudices of the whites and the \"grudge\" of the blacks, one would like the other. That's why he had the idea of sending away black people to Africa, they couldn't be in America. A utopia of the white nation. Then, Haiti could be an option to send black people away.\n\nIn another document, in 179, it is also noted that he feared that Haiti would become a land of pirates, an \"American Alger\".\n\nSince the book isn't about Jefferson, I can only give some very general lines on what he thought, based on the thesis and arguments of the author, that I also presented very generally. I hope I could grive you some guidelines to your question, if it's not clear I can try to give a more detailed response *on the subjects of book.* \n\nEdit to provide the link."
]
} | []
| []
| [
[
"https://www.gilderlehrman.org/sites/default/files/inline-pdfs/T-08063.pdf"
],
[
"https://books.openedition.org/pur/43694"
]
]
|
|
2btftz | why hasnt a large group of people filed a class action suite against verizon or comcast | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2btftz/eli5_why_hasnt_a_large_group_of_people_filed_a/ | {
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"text": [
"Many service providers in the US, including Comcast, have clauses in their user agreements which actually forbid customers from engaging in class-action lawsuits against the company. In fact, many of these user agreements prevent you from taking any legal action and mandate that all disputes (that can't be resolved directly with the company) must be settled outside of court through binding arbitration.\n\nYes, it is true that these clauses are not legally enforceable in all jurisdictions, but it still prevents and discourages many customers from trying to get a class action lawsuit going. Also, these lawsuits are extremely expensive and unless you have demonstrable proof that the company caused widespread harm/damage and/or acted illegally then it simply doesn't make sense to proceed with such a lawsuit.",
"For what, exactly?",
"Why has not each individual citizen sued the US government for stalking???"
]
} | []
| []
| [
[],
[],
[]
]
|
||
2wyjzk | why don't we have nintendo wii styled controls for a computer instead of the conventional mouse? | i have my computer hooked up to my TV as a monitor, which is pretty common these days for a lot of people. im just wondering why we don't have the system for controlling your cursor on screen like you do when using the nunchucks on the Wii, but for computers. instead of using an optical mouse that has to move across a surface to register where you want to move your cursor on screen, why aren't we just pointing directly to the screen to control the cursor. i understand that this probably wouldn't be too practical for desktops but this seems like it would a really good system for people like me sitting in a lounge chair with a 30+ inch screen.
EDIT: i don't necessarily mean the wii-mote specifically, just that general method of controlling the cursor about the screen, i.e. pointing something directly at the screen and using that as your control surface instead of moving something on a virtual plane like a tabletop. as a crude visual metaphor -- picture it like your remote control for your television. you don't hold your arm out from your body, your elbow rests against something comfortably and you point the remote at the screen so the tv can read it. now translate this method to on a computer screen, with some sort of sensor (?) that reads the screen and tracks your movements, moving the onscreen cursor. so now picture it like its your remote but it has a laser pointer attached to it(crude metaphor) and where you point the red dot is where the cursor goes, you would only have to move your wrist really, one hand with the remote and the other on the keyboard when necessary, set it down when you need both hands to type. im not thinking about sitting at a desk but sitting in front of the TV on the couch or something.
so i guess this is really a two part question, 1) does this technology exist. 2) if not, why not (technical, practical, im a moron, ???) | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2wyjzk/eli5_why_dont_we_have_nintendo_wii_styled/ | {
"a_id": [
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"score": [
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3
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"text": [
"Because The wii mote is very imprecise for clicking. The ergonomics don't really work well for the complexities of computers.",
"If you have a bluetooth adapter in your computer, [you can absolutely use your Wiimote that way](_URL_0_).\n\nTurns out most people just don't want to do this. The novelty wears off quickly. Mice were designed to provide maximum control with minimum effort. Wiimotes were designed almost exactly the opposite. Large gestures with less focus on precision."
]
} | []
| []
| [
[],
[
"http://www.makeuseof.com/tag/how-to-connect-your-wiimote-to-your-pc/"
]
]
|
|
5xmc03 | what is a typical career path taken to become a us ambassadors? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/5xmc03/eli5_what_is_a_typical_career_path_taken_to/ | {
"a_id": [
"dej6trm"
],
"score": [
2
],
"text": [
"You can be anything you want! You just have to earn a lot of money. Then you donate it to a political party, and use that donation as leverage to get the position!"
]
} | []
| []
| [
[]
]
|
||
2zz6ls | what do pets think about all day? they must get bored. | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2zz6ls/eli5_what_do_pets_think_about_all_day_they_must/ | {
"a_id": [
"cpnmywz"
],
"score": [
3
],
"text": [
"Some do which is sometimes why bored dogs for instance destroy furniture"
]
} | []
| []
| [
[]
]
|
||
45s5wb | excess reserves | Watched Janet Yellen's testimony to congress last week. We pay millions of dollars to Wall Street banks to hold their money in the Federal Reserve. Somehow we also make money on the deal. Yellen seemed to be saying that if we didn't pay Wall Street to hold their money we would have less money going into the Treasury to pay down the debt and pay for things in the federal budget. How does this work? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/45s5wb/eli5_excess_reserves/ | {
"a_id": [
"czzwfrg"
],
"score": [
2
],
"text": [
" > Watched Janet Yellen's testimony to congress last week. \n\nFor those of who do not want to use up all of our bandwidth, or week-end time, watching 6 hours of very boring you-tube, could you point us to the part that you are talking about?"
]
} | []
| []
| [
[]
]
|
|
5rwsvb | how can gov officials get away with giving seemingly classified information to news outlets? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/5rwsvb/eli5_how_can_gov_officials_get_away_with_giving/ | {
"a_id": [
"ddarf50"
],
"score": [
2
],
"text": [
" > The official was not authorized to speak publicly on the subject\n\nThat is not the same thing and does not imply that they gave out classified information. What it means is that the employee was not designated as the public spokesperson for the organization. The information they are giving is not secret, but not the official line either."
]
} | []
| []
| [
[]
]
|
||
9zus8o | why don’t you bleed out when you get an injection? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/9zus8o/eli5_why_dont_you_bleed_out_when_you_get_an/ | {
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"text": [
"There is about 50 processes that occur to act together to clot your blood and plug the hole.\nSome people could bleed out, they are called haemophiliacs, and their blood clotting system malfunctions in one way or another.\nBonus fun fact for you, if you take too many blood thinners, you can bleed out through your skin, don't even need a hole.",
"The needle hole you get from an injection is so tiny that the blood can't get out that much. Even when you get stung by a sowing needle, which is considerably larger, it doesn't bleed that much either. ",
"Depends on where the injection is.\n\nMost simple injections are intramuscular, given into the deltoid or quadriceps muscles in the upper arm or thigh, respectively.\n\nThese muscles are chosen because they don't have any major blood vessels running through them, only really really tiny ones that supply the local tissue. These get torn, but not enough to create significant amounts of blood. As these microscopic vessels are ruptured, tiny little cells in the blood called platelets come into contact with the muscle tissue. Usually, platelets are inside the blood, but when the vessels breaks they spill out.\n\nAs soon as the platelets recognise that they're not inside the blood vessel, they start to 'vomit' lots of 'glue' into the local area. This causes more platelets to stick, and vomit more glue. This glue is like an epoxy -- you need to mix it so that it sticks. Because the platelets are vomiting their part, it can now mix with the parts in the blood, causing more stickiness to happen.\n\nThe end result is that you get this big ball of platelets, red blood cells, and other stuff all stuck together. If you scrape your knee, you'd call this a scab, however it's happening hundreds of times inside your muscle after any injection. Sometimes, this glue doesn't form very well, and you get bruises where you got the injection. That's because the glue took too long to form and too much blood leaked out!",
"Your blood hates oxygen. When your blood touches oxygen, it turns into an Iron Snow Flake in order to stop it getting into your body. When the needle goes into your skin, some blood will come back out the hole when the needle leaves. The Iron Snow Flakes that your blood turns into lock together, and \"freeze\" in place. This \"Frozen\" blood blocks any more blood from escaping."
]
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| []
| [
[],
[],
[],
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|
||
b6ja5e | how does property line surveying work? | I work in an industry where we use property legal descriptions and have to order property surveys regularly. I don't fully understand what the surveyor does when he goes out to a property to survey it.How does he get the actual measurements? What do the hrs/mins/secs mean exactly?Just trying to get an understanding of how this part of things actually happens.
EDIT: I'm looking for info on property line/real estate surveying, not so much the engineering sort of surveying. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/b6ja5e/eli5_how_does_property_line_surveying_work/ | {
"a_id": [
"ejkq3yd",
"ejkspdy"
],
"score": [
2,
2
],
"text": [
"Property lines is often described using features in the terrain and not necessarily coordinates. And even if there is coordinates they may not have been measured with high accuracy, using old datum or the terrain might have changed. So a surveyor is walking around trying to make sense of the previous descriptions of the property lines and writing down his own descriptions. This makes it easier for you to know where the property line is. He often returns with detailed coordinates of the property line. These can be written as two sets of degree, minute, second coordinates. A latitude and longitude. A circle have 365 degrees, a degree have 60 minute and a minute have 60 seconds. So by using two such values you are able to uniquely place a point on the surface of the Earth.",
"It's all about making maps align with reality. Property is defined, for ownership reasons, by polygons on a map. Usually the local government maintains master maps reflecting agreed upon boundaries between each parcel of land.\n\nIn most of the 20^th century, these were literal maps, sheets of paper in big books in the county's land records department. When you filed a deed and filed for title, the map you provided was compared, by a skilled map reader, with the book. Many title defects were detected this way, and many, many more were not.\n\nIn modern times, most jurisdictions are digitizing these maps. The resulting GIS (geodesy information system) allows computers to find all the zillions of other boundary defects, and arithmetically fix them. Today, all good plots have coordinates on them, like your car's GPS uses; rocks and landmarks are part of the sad past.\n\nWell, it's super good that all the county's records are now in unified GIS, but that's little help to the contractor on the ground. Surveyors take those maps and use them to put matching stakes in the ground. They measure from a nearby reference point, shown on the map and perhaps by a marker on the ground, to locate a site point of reference. From there, it's measuring and following the map, and hammering stakes with pretty ribbons tied to them. Most measurement is optical, but differential GPS is accurate enough for some applications."
]
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| [
[],
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]
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2jn9fc | Isn't it somehow obvious that mathematics don't work with infinite values? | askscience | http://www.reddit.com/r/askscience/comments/2jn9fc/isnt_it_somehow_obvious_that_mathematics_dont/ | {
"a_id": [
"cldexq4",
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"text": [
"Hidden inside your question is another very philosophically deep question: how does math work? As philosophers and mathematicians have concluded over the last few millienia, mathematics \"works\" by establishing a set of ground rules (called \"axioms\") and deducing consequences based on these rules.\n\nMany of the currently-used axioms are quite obtuse, but here's an example of some axioms for arithmetic on the natural numbers (these are often called the Peano Axioms). Note that I'm not hoping to do this in full formality, but mostly to give an example of how math is built from the bottom up.\n\n1. There is a natural number called 0.\n2. Every natural number *x* has a successor, S(x), that is also natural.\n3. If x and y have the same successor (i.e. S(x) = S(y)), then x = y.\n4. For no natural number x is S(x) = 0.\n5. For any x, x + 0 = x (\"additive identity\").\n6. For any x and y, x + S(y) = S(x + y) (this can be interpreted as saying x + (y + 1) = (x + y) + 1, but we use this weird notation because we haven't even defined \"1\" yet!)\n7. For any x, x \\* 0 = 0.\n8. For any x and y, x \\* S(y) = x + (x \\* y) (this is like distributing x\\*(y+1) to get x\\*y + x).\n\nIt's important to note that we never actually defined \"1\", \"2\", \"3\", and so on. Those are taken to be representations of numbers that correspond to S(0), S(S(0)), and S(S(S(0))), respectively. \n\nFrom here, we can prove the obvious things like commutativity (eg. x + y = y + x), associativity (eg. (x \\* y) \\* z = x \\* (y \\* z)), that S(S(0)) \\* S(S(0)) = S(S(S(S(0)))) (i.e. 2 \\* 2 = 4), and tons of other facts. Thus, we have an established set of ground rules from which addition and multiplication are defined. We built these rules to agree with our intuition for addition and multiplication, but once we accept these rules they take a life of their own and allow us to begin proving other facts (that may or may not themselves not be immediately intuitive) without any philosophical quarrels about the underlying essence of the plus sign butting in.\n\nNow let's get back to infinity. For this, we need to skip a few steps (I don't want to get into defining what a set is, or what the size of a set is), but one of the simplest ways to define an infinity is by looking at he number of natural numbers there are. Certainly, the collection of natural numbers does *not* take the form S(x) for any number x, so we want to say that its size is \"infinity\" (as it turns out, reasonable definitions of infinity allow for it to take various sizes, and this one ends up being given the name \"countable infinity\" or \"aleph-zero\", but that is slightly tangential to our ongoing discussion).\n\nOkay, so the set of naturals is {0, S(0), S(S(0)), ...}. I don't think there's any disagreement there. But now let's look at the set of natural numbers that are successors of other naturals. That is, the set {S(0), S(S(0)), S(S(S(0))), ...}, i.e. taking the successor of every element in the set defined two sentences ago. This is almost like the set of natural numbers, but it's missing zero! Put another way throw 0 into this set, we get the natural numbers again. This is exactly what's going on inside Hilbert's hotel: bump everyone up a room, and now we have room for one more before we're full again.\n\nThough initially counterintuitive, this isn't a problem for mathematicians who deal with infinity on a daily basis. Further, if you want to say that this is \"wrong\", you'd have to argue that one of the axioms used to build up to this conclusion is incorrect; as this \"paradox\" is what we get by simply putting a few of them together. Importantly, this ability to seemingly make room out of thin air ends up being very useful in practice, and is implicitly used all the time in number theory, programming, and so on, without any major hitches.",
"It isn't even obvious to me what you mean by \"Isn't it somehow obvious that mathematics don't work with infinite values\".\n\nInfinity is in many ways a surprising, counterintuitive, and complicated topic, and many things about it are difficult to understand, especially if by way of human-language analogy. In fact there have been great mathematicians of relatively recent times who thought that some modern notions of infinity, now virtually universally accepted by mathematicians, were outright nonsense. For example, not much more than 100 years ago, Leopold Kronecker thought that theories about infinity developed by his contemporary Georg Cantor were ridiculous, garbage, and non-mathematical. Cantor's work is now viewed by modern mathematicians as completely uncontroversial (and not merely \"completely uncontroversial\" - they're viewed as the underlying basis of one of the most important, fundamental topics in mathematics).\n\nSo thinking \"that doesn't make sense\" upon hearing various things about infinity actually puts you in good mathematical company. But you thinking it doesn't make sense doesn't change the fact that it does, in fact, make sense."
]
} | []
| []
| [
[],
[]
]
|
||
28qe4v | why do computers need screen savers but not tvs? | Computers traditionally have screen savers that come on after a couple of minutes. TVs can be on for hours but don't have screen savers. Why not? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/28qe4v/eli5_why_do_computers_need_screen_savers_but_not/ | {
"a_id": [
"cidei5o",
"cidf2fx",
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"score": [
6,
24,
13
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"text": [
"My TV has a screen saver",
"Because of [screen burn-in](_URL_0_).\n\nIf you let an old CRT screen display the same image for a longer period of time, that image can be permanently burnt into the screen. (check the link for examples.)\n\nOn TVs this wasn't a huge problem since TVs don't tend to show a lot of static images for long periods of time. Although you could sometimes find a TV with the faint ghost of a channel logo in one corner because it had been on one channel for too long. \n\nOn computer monitors the problem was much greater since you could end up with an entire document burnt into your screen if you forgot to turn it off. So screen savers were implemented that could either blank the screen or show a continuously moving image, screen savers literally saved screens.\n\nBurn-ins aren't that likely to happen on modern displays. It used to be a problem with plasma TVs and it can apparently even happen on an LCD display although I've never seen it. Plus most TVs and computers today will turn the screen off automatically if it sits idle for too long and that's a better solution than a screen saver since it saves power.",
"Slightly unrelated, but my Grandmother watched QVC so much in the late 1990s/early 2000s that the phone number was permanently burned into her CRT tv screen. "
]
} | []
| []
| [
[],
[
"http://en.wikipedia.org/wiki/Screen_burn-in"
],
[]
]
|
|
30sfp2 | Why did China move to simplified characters instead of the traditional ones? | Was there any benefit for doing this? I've never heard of any similar instances.
| AskHistorians | http://www.reddit.com/r/AskHistorians/comments/30sfp2/why_did_china_move_to_simplified_characters/ | {
"a_id": [
"cpvdily"
],
"score": [
3
],
"text": [
"Short version: because traditional characters, while they make more sense while learning them, are a pain in the ass to write and look very intimidating. The stated benefit was that more people would become literate, which happened (for various reasons)\n\nLonger version deals with Mao's apparent desire to replicate the First Emperor, revolutionary doctrine saying out with the old, and just general \"uplifting the workers\" themes in Communism. The benefits of switching to simplified can be seen by comparing the character 认, \"to know\" with its traditional counterpart, which I can't write on mobile."
]
} | []
| []
| [
[]
]
|
|
1026ju | Is there any evidence or possibility of truth to the theory that Psilocybin Mushrooms Contributed to Human Evolution? | Terrence McKenna theorized that psilocybin containing mushrooms (shrooms) was what made possible the incredible increase in brain power of humans in the last 100,000 years. First of all, how incredible was this increase in brain power? And could a substance actually be able to contribute to this? | askscience | http://www.reddit.com/r/askscience/comments/1026ju/is_there_any_evidence_or_possibility_of_truth_to/ | {
"a_id": [
"c69sc3w"
],
"score": [
4
],
"text": [
"No. It's a fun theory to entertain if you do a lot of drugs, but that's not how evolution (at this stage) works. Basically, evolution comes from mutations that are passed down through heredity. In other words, even if you gained a higher level of consciousness through pscilocybin mushrooms, this trait wouldn't be passed on to your offspring. Perhaps the innate desire to eat them would be passed on, but then we would still be eating them just to stay more \"intelligent\" than apes."
]
} | []
| []
| [
[]
]
|
|
30vr4s | why is the proportion of left-handed people so small in comparison to right-handed people? shouldn't it be closer to 50:50 than the 10:90 ratio we see today? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/30vr4s/eli5_why_is_the_proportion_of_lefthanded_people/ | {
"a_id": [
"cpw9uym"
],
"score": [
3
],
"text": [
"Once humans starting using tools, handedness started to matter. A left handed person would be a disadvantage using tools make for right handed people.\n\nOn the other hand, with weapons, being left handed could be an advantage, if everyone was used to fighting right handed people. So there would be an evolutionary reason to keep some left handed people around."
]
} | []
| []
| [
[]
]
|
||
17no3n | Can tungsten survive lava? | I read that tungsten boils at like, 3000 degrees Celsius, and that lava burns at around 900 to 1200 Celsius, so what would happen if you put tungsten in lava? (I'm assuming it's pure, because unpure is supposed to be brittle?) | askscience | http://www.reddit.com/r/askscience/comments/17no3n/can_tungsten_survive_lava/ | {
"a_id": [
"c875g3n"
],
"score": [
3
],
"text": [
"Tungsten **melts** at 3422°C (it boils at a much higher temperature). Pāhoehoe is one of the hotter types of lava, at about 1200°C.\n\nSo nothing would happen. It would get hot, but not melt. There are plenty of elements/metals that have melting temperatures hotter than 1200°C, like titanium, platinum, etc."
]
} | []
| []
| [
[]
]
|
|
g139e | ferrofluid carrier fluid? | I'm looking for something to hold my ferrofluid in as I bought some of the raw stuff which stains like hell and makes glass dirty. Also water kinda works but it really weakens the effect of the fluid i.e. it loses it's spikes.
So I was wondering if there is something that could keep it suspended, working and from staining the glass.
Example what it does: _URL_0_ Example what i'd like it to do: _URL_2_
_URL_1_ | askscience | http://www.reddit.com/r/askscience/comments/g139e/ferrofluid_carrier_fluid/ | {
"a_id": [
"c1k5ft9"
],
"score": [
3
],
"text": [
"Did you make the carrier fluid yourself?\n\nWhat was it already made out of?\n\nA quick perusal of google suggests it's most commonly made with Kerosene and Oleic acid."
]
} | []
| [
"http://www.liv.ac.uk/chemistry/Events/SchoolsEvents/Ferrofluids/photos/ferrofluid_spikes.jpg",
"http://www.reddit.com/r/chemistry/comments/g134y/ferrofluid_carrier_fluid/",
"http://www.interactivearchitecture.org/wp-content/imagebank/fluid_demo.jpg"
]
| [
[]
]
|
|
73s4xx | how can an mri show the side of the body if the person is lying on their back? | E.g. Injury to the side of a knee but injured side isn't facing up, etc. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/73s4xx/eli5_how_can_an_mri_show_the_side_of_the_body_if/ | {
"a_id": [
"dnsneqj",
"dnsuwtm"
],
"score": [
3,
2
],
"text": [
"It scans all around you, not just from one direction. \n\n[MRI machine](_URL_0_). See how it is round and surrounds your entires body?",
"MRI machine image all around you producing a 3d image. You can then view this image from multiple directions (known as planes) and move in and out of that plane. The side image is known as a saggital plane. You can also view it front to back (coronal), top to bottom (transverse) or I think it also possible to view it at other angles (oblique). Usually the image you see is the just the image that shows what they are looking for best, after the whole scan has passed through the computer and been reviewed by the radiographers, radiologist and doctor who is showing you it. "
]
} | []
| []
| [
[
"https://upload.wikimedia.org/wikipedia/commons/b/bd/Modern_3T_MRI.JPG"
],
[]
]
|
|
egxzul | how is digesting liquids possible? | How can a liquid (stomach acid) digest another liquid And also How does stomach acid not get diluted by other liquids | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/egxzul/eli5_how_is_digesting_liquids_possible/ | {
"a_id": [
"fcauksr",
"fcbfdkt"
],
"score": [
3,
2
],
"text": [
"Digesting is just breaking down things into small things, then breaking those down into tiny things so you can absorb them. You break proteins down into little amino acid blocks, break down carbs into small pieces, and break down fats into little fatty acids. Your body absorbs those, along with a lot of the water you ingest. Everything being liquid means you can mix the digestive liquids with the food more easily.",
"It kind of depends what liquid we're talking about, because liquids can be digested. Like olive oil is made up of mostly unsaturated fatty acids, which is the good kind of fat. Your body then breaks down the fatty acids in to smaller fatty acids that can be absorbed (olive oil is kind of a bad example as it's mostly simple fatty acids which can't be broken down more, but other fats are more complex and need to be broken down).\n\nBut some liquids can't, something like soda has dissolved solids in it but the carbonated water isn't 'digested' in the sense that something gets broken down. Water can't really be broken down. However stuff in water can be broken down. Like some sugars. \n\nWhat's interesting is for things to be digested they have to be a liquid. This is why we chew and then our stomach dissolves everything into a big soup which the small intestine puts out stuff to breakdown the stuff we need if it's too complex.\n\nStomach acid does get a little diluted, but your body just makes more and puts plenty to soupify any food that goes in. It also gets a little bit more complicated because your body also uses something with the acid to break stuff down, but that's not important to what you were asking."
]
} | []
| []
| [
[],
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|
1d442w | Why was human anatomy poorly drawn in ancient works of art? | Such as this Greek Art of [Hercules](_URL_1_), yet [the statue](_URL_0_) is more anatomically accurate?
Another more recent example being a painting by a follower of Hieronymous Bosch, showing [Christ in Limbo c.1575](_URL_3_)
In just a few hundred years, people began to paint more [like this](_URL_2_)
* What is the reasoning behind it? Just a style of art?
* At what point did people begin to worry about structure, and photo realism?
* Is this why painting such as the Mona Lisa are so profound? | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/1d442w/why_was_human_anatomy_poorly_drawn_in_ancient/ | {
"a_id": [
"c9mrql1",
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5,
2
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"text": [
"Not a professional historian, but I have read much on this on my own. Really the question here is fundamentally about the purpose of representational art.\n\nIn many cultures, paintings were not meant to be interpreted at face value, but rather as symbols. Anatomy is rather irrelevant when a culture simply uses painting as a tool to narrate a story or glorify a particular religion.\n\nI'll give one example. It's pretty clear the ancient Egyptians were perfectly capable of creating naturalistic depictions of human beings, just look at this [bust of Nefertiti](_URL_0_). But the relief sculptures/paintings that come to mind when one thinks of \"Ancient Egyptian art\" have nothing to do with naturalism and everything to do with symbolism. There is a complex language of artistic rules there that speaks to their mythological narratives, which requires a basic understanding of their culture to interpret. European romanesque and gothic painting can be explained in a similar way. Outside of the western historical tradition, just look up Mughal or Edo-period Japanese paintings for further examples of stylistic symbolism over naturalism.\n\n(Of course, the Renaissance artists, Mannerists, Neo-Classicists etc were heavy on symbolism as well, symbolism and naturalism aren't mutually exclusive.)\n\nSo it's not so much a question of whether certain cultures *could* create art with naturalistic anatomy or not, but rather the question is what purpose did painting serve in different cultures, and why?",
"*I'm not an art historian.*\n\nSomething that bothers me about these answers is that the development of sculpture is independent of the development of painting. There's no reason to think the Greeks or Romans could paint realistically just because they could sculpt realistically. To claim painting would have been realistic if it wasn't so symbolic is a bit pat. Techniques for realistic painting took centuries to develop. \n\n* There's no reason to think Fra Angelico would not have liked to paint in a more realistic style, and some evidence that he did. For example, his San Marco Annunciation of 1450 features improved perspective over his more famous Cortona Annunciation of 1433. The San Marco Annunciation indeed features less symbolic elements, but I find it hard to take that as an *explanation* for the improvement in perspective.\n\n* The Miraflores Altarpiece c 1435 of Van der Weyden looks like a 3D version of a perspective-less painting of the Middle ages. The figures feel planted upon the same dioramic stage, yet shadow rounds their features, and architectural perspective gives realistic depth to the background.\n\n* The Flagellation c. 1450-1460 of della Francesca features more depth of figures, with a group appearing larger and closer to the viewer, and another smaller group appearing further away. But the perspectival powers of della Francesca is not that of Van der Weyden, and the columns feel all wrong. \n\n* Botticelli's The Birth of Venus c. 1485 is clearly cartoonish, even though it attempts to represent realistic figures. And this is true of everything he painted. Was it a choice? I don't think so. There is no variation in this fundamental fact. See Titan's painting of the same for contrast.\n\n* Bosch managed to paint somewhat realistic figures. See his The Crowning of Thorns c. 1490-1510. Yet his Christ Carrying the Cross c. 1510-1516 features grotesque figures. This must be explained by his obsession with grotesques and not his ability. Yet scenes featuring numerous bodies do always feel simplistic and flat. And this may be due to his inability to overcome past representations. I'm not aware of any full figure realism in Bosch.\n\n* Compare to Bronzino's Venus Disarming Cupid c. 1545 which clearly shows mastery of shadows to produce three dimensional human figures. All of his work leads up to this or features it. I see no regression to flat figures for the sake of symbolic expression.\n\nNone of this proves anything, but \n\n1. if you look at the style of each individual painter, you'll notice they do not vary their work especially depending on how symbolic it is. Instead, you get the distinct feeling that all of these artists are trying as best they can to present realistic figures, with the possible exception of Bosch. \n\n2. there is a definite feeling of advancement over time from flat perspective-less representations to full figuration featuring control over perspective. \n\nSo it is quite possible, especially if the extant Ancient paintings are crude, that painting never attained to the level of sculpture in its realism or anatomical correctness, perhaps for lack of proper materials, or lack of sustained cultural or institutional interest in painting. Realism in painting isn't something that just falls off the brush.\n\nEdit: There is one reason to think the Ancients could draw anatomically: anatomically correct sculpture followed anatomically correct painting during the Renaissance. It suggests the ability to see figure in sculpture is somehow related to the ability to see it in painting. However, in a culture that began with monumental sculpture and gradually humanized it, painting might still be a superfluous addition, rather than a point of origin. But the reliefs of the Elgan Marbles suggest a graphic intention. Flatness there is nearing that of paper... I still think it's quite plausible ancient painting was just not an important craft. There was, to my knowledge, never a period of realistic portraiture on Greek pottery. Byzantine portraiture (and icons) are well known for being cartoonish and not realistic. Shall we explain its anatomical simplicity by way of style or regression or simply the absence of sufficient art? I choose the latter.\n\nEdit: \n\n > Is this why painting such as the Mona Lisa are so profound?\n\nThe Mona Lisa apparently only became world famous once it was stolen in the early 20th century."
]
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"http://www.art-prints-on-demand.com/kunst/anonymous/statue_hercules_hi.jpg",
"http://www.theoi.com/image/K9.6Ares.jpg",
"http://i.imgur.com/DQCOvBx.jpg",
"http://upload.wikimedia.org/wikipedia/commons/3/3c/Follower_of_Jheronimus_Bosch_Christ_in_Limbo.jpg"
]
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"http://en.wikipedia.org/wiki/Bust_of_Nefertiti"
],
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ezz0t4 | what is technical the difference between a thread and an async-operation? | I assume that two threads are working on a single cpu like this:
| Thread1 | Thread2 |
|---------|---------|
| a1 | b1 |
| a2 | b2 |
| a3 | b3 |
And are batched like this on the CPU
a1-b1-a2-b2-a3-b3 | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/ezz0t4/eli5_what_is_technical_the_difference_between_a/ | {
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"A thread is a *long-lived* independent running part which is *initiated by the main program*, for example receiving traffic from a network device and once it has received enough, inform the main program that the data is there.\n\nAn asynchronous operation is a *short-lived* independent running *stub part* which can be initiated by anything, for example the writing of analysed data to disk.\n\nNow it is fair to say that asynchronous operations are threads also and could be implemented as threads by the coder too and that is 100% true. It is just that their purpose is different (Long lived versus long lived) and where they are started (main program versus at the end of some process).",
"A thread is when you ask the operating system to start running another part of the program at the same time. If there are more parts running than CPU cores, the operating system will switch between them. Threads have a bunch of features (like separate stacks) that make them relatively \"expensive\". A program shouldn't have thousands of threads because it will waste memory and time.\n\n\"Async tasks\" depend on the programming language, but they're generally things you can do in the background that are too short to be their own thread. The program will create one thread (or a few) and then that thread (or those threads) will do async tasks whenever they are ready to be done. This means a new thread doesn't need to be created for every task.\n\n\"Async tasks\" can also be things that don't use a thread at all, as long as the program can remember it's waiting for something to happen. For example, waiting for the user to type something could be an async task. The program won't use a thread to wait for the user to type something (because that's a waste of a thread) but it knows that when the user does type something, the task should be marked as completed.\n\n\"Async tasks\" got a big boost in popularity some time ago because: people wanted to do more things asynchronously (in the background), people realised that having a thread for every single thing is not efficient, and because JavaScript basically forces you to use them so people got used to them.",
"Here is an analogy that might help.\n\nLets say you're busy but you need to drop your car to the garage for a service then pick it up later. \n\nYou could delegate this to someone else: they bring your car to the garage, sit around until its fixed and drop it back. The upside is you can work away as normal. The downside is you need to find someone else, and they're wasting their time waiting for your car to be fixed.\n\nOr you could try to find 10 spare minutes in the morning to drop it down, and 10 minutes in the afternoon to collect it. The downside is its 20 minutes out of your day, and more work coordinating your time. The upside is you can do it all yourself and nobody is waiting around.\n\nThe first is kind of like a thread, the second is kind of like an async task."
]
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112zx6 | What started the European explorers craze that got them discovering the new world and Asia? | Was it just searching for trade? Why did it start then and not in the past? And why was it just Europeans doing the explorations? | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/112zx6/what_started_the_european_explorers_craze_that/ | {
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"Money, prestige, and the struggle for dominance over rival nations. The usual suspects.\n\nIt started with Portuguese attempts to corner the spice trade to and from the East Indies by getting ships around Africa (to circumvent the Ottoman control of the ancient overland routes), which was made more complicated by the fact that their instruments didn't work well as one approached the equator. In any event, since one voyage could at times result in a profit of 400% or more, this dangerous effort was more than worthwhile.\n\nAlso, it wasn't just Europeans. China sent out large fleets to explore Asia and East Africa as well. This stopped when a later emperor decided to end the expeditions. As a unified state, they could do that. If a European king chose to end such efforts, all that would mean is that one of the neighbours would eventually take up the challenge instead. "
]
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[]
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|
atrl6u | investing: buying stocks, selling stocks. eh? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/atrl6u/eli5_investing_buying_stocks_selling_stocks_eh/ | {
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"A stock is a piece of the company. If the company issues 1000 stocks, and you own 100 stocks, you essentially own 10% of the company.\n\nThe main reason for buying stocks is investment. If the company makes a profit, the company is worth more, so your share of the company is worth more. The company may also pay out dividends to shareholders, essentially splitting part of their earnings with the owners.\n\nThe price of a stock depends heavily on investor confidence. If you believe a company will do well, you are willing to buy their stock and this raises share prices. If the company is failing, you will sell off the stock, and the share price falls.\n\nYou can buy stocks through a stock broker, or sometimes directly from the company (if you are rich)."
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ew4ev5 | why does a yawn filter out any deep bass sounds? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/ew4ev5/eli5_why_does_a_yawn_filter_out_any_deep_bass/ | {
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"The inner ear is normally sealed, air can’t get in or out. However there is a tube connecting it to the throat so that pressure can be equalised. When you yawn these tubes open. The same thing happens when you swallow and is why when your ears ‘pop’ , like in a plane, swallowing or yawning can fix it. It equalises the pressure.",
"if you are describing what I think you are, the \"tingling\" is most likely the tensing of a muscle in your ear, the tensor tympani. some people can voluntarily flex this muscle which is usually referred to as \"ear rumbling\". check out /r/earrumblersassemble for more info!"
]
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2h0ahi | If fusion naturally occurs in stars, does fission occur naturally anywhere or only under manmade conditions? | askscience | http://www.reddit.com/r/askscience/comments/2h0ahi/if_fusion_naturally_occurs_in_stars_does_fission/ | {
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"A few nuclei, including some uranium isotopes, fission spontaneously. However this process is very rare. Most fission processes are induced by neutrons, which requires a large assemblage of radioactive and fissile material, and the right geological environment. This happened naturally at least once in the Earth's history. See these articles [[1]](_URL_0_), [[2]](_URL_1_). The second one is more technical."
]
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"http://en.wikipedia.org/wiki/Natural_nuclear_fission_reactor",
"http://mragheb.com/NPRE%20402%20ME%20405%20Nuclear%20Power%20Engineering/Natural%20%20Nuclear%20Reactors,%20The%20Oklo%20Phenomenon.pdf"
]
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|
||
skwpw | What natural disaster significantly changed the course of history? | Aside from the black plague(which probably isn't considered to be part of this category), I've heard very little in regards to this question.
What would you consider to be one of the most important/significant natural disasters in history? Frankly ANY sort of information would be fascinating to me. | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/skwpw/what_natural_disaster_significantly_changed_the/ | {
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"I guess pompeii might be one, but did that really alter the course of history by a large degree?",
"The [Lisbon earthquake](_URL_0_) of 1755 had a profound effect on enlightenment philosophy. All the churches were destroyed and a huge number of people killed on All Saints Day. This led an entire generation of influential philosophers, including Voltaire and Kant, to question the existence or benevolence of God.",
"Well, there's the [Year Without a Summer](_URL_0_) which was the result of a volcanic eruption which had worldwide effects.",
"If you don't want the Black Death (aka the Plague, you shouldn't mix and match the names here), or [other pandemics](_URL_1_) (see also [this](_URL_0_), I've got a related thing:\n\n[The Little Ice Age](_URL_10_) after the [Medieval Warm Period](_URL_7_). Fascinating bit about researching by using paintings of winter scenes as sources for this [here](_URL_6_). In this context, there's also the [Great Famine](_URL_2_).\n\nAnd while we're on the topic of famines, there's of course the [Great Irish Famine](_URL_4_), that more or less kick-started Irish emigration to the US.\n\nThe wiki also has a [List of natural disasters](_URL_8_) throughout history.\n\n\nEdit: I almost forgot: There's also the original [Kamikaze](_URL_9_), a storm that prevented the Mongols from conquering Japan - **twice**!\n\nSecond Edit/Addendum: The Famines especially, were significant in an intellectual way: They were, among others, the inspiration for [Malthus](_URL_3_), who in turn influenced Darwin and, subsequently [Social Darwinism](_URL_5_), and, subsequently, the Nazis, and on and on and on....\n",
"Strictly speaking, this isn't an historical natural disaster - it's a *pre*historic event. But, it was definitely one of the most significant natural disasters in human existence.\n\nThe Toba volcano super-eruption about 71,000 years ago [\"plunged the planet into a 6-to-10-year volcanic winter and possibly an additional 1,000-year cooling episode.\"](_URL_0_)\n\n\n\n > [Mount Toba's eruption](_URL_1_) is marked by a 6 year period during which the largest amount of volcanic sulphur was deposited in the past 110,000 years. This dramatic event was followed by 1000 years of the lowest ice core oxygen isotope ratios of the last glacial period. In other words, for 1000 years immediately following the eruption, the earth witnessed temperatures colder than during the Last Glacial Maximum at 18-21,000 years ago.\n\nIt is believed that the ancestral population of Homo Sapiens reduced to less than 10,000 people during this period. And, because this event occurred just after a mass exodus of Homo Sapiens from Africa, there were pockets of small populations left surviving in a few places across Eurasia.\n\nIt's likely that these small isolated populations became the various races we see today.\n\nSo, the Toba eruption may have *caused* humans to differentiate into different races. That's significant.\n",
"The Mongols attempted to invade Japan in 1274 and 1281. Both times, their fleets heavily outnumbered the Japanese fleets, and both times the Mongols were repelled by typhoons.",
"I immediately thought of the [Laki Eruption of 1783](_URL_0_). This volcanic eruption in Iceland disrupted weather patterns throughout Europe which led to numerous crop failures. These crop failures led to food shortages which in turn put great stress on the lower classes of French society. The stress of food shortages as well as the disruption to trade (in some areas ships were stuck in their ports due to the volcanic haze) set the stage for the French Revolution. \n\nThe eruption may not have been a necessary or sufficient cause of the Revolution, so it may not qualify for the question, but it was definitely a contributing factor.",
"I'm surprised the [Santorini eruption](_URL_0_) wasn't mentioned yet. The extent to which it was destructive, and the effects of the preceding earthquakes and ensuing tsunami, are all contested, but it seems to have been a major catalyst in the downfall of the Minoan civilization, and might have served as a basis in part for Plato's Atlantis.",
"I'm surprised someone hasn't mentioned the [desertification of the Sahara](_URL_0_), which wikipedia dates to reaching its modern extent at 3400 BC. Given the extensive records of people living at least partially sedantary lives there quite comfortably beforehand, it must have displaced quite a lot of people.\n\nLikewise, it has been suggested that the climate becoming more hostile contributed to the change between the circa 300bc-300AD Arabia that seems to have been very prosperous and its more arid state today. This seems to have been most noticeable in the south, as modern Yemen was referred to as 'Arabia Felix', 'lucky' Arabia or 'happy' Arabia, supposedly due to its immensely wealthy cities.\n\nI also had it suggested in a BBC documentary that the growth in aridness of the climate of Somalia and Ethiopia contributed to the collapse and dispersal of the groups that had been part of the Kingdom of Aksum. But that documentary was a while ago and I haven't seen many references to it since.\n\nMy overall point is that it's clear that the changing climate of the earth has had a massive impact on development, habitable areas, and population sustainability.",
"It is widely assumed that a tornado actually drove the British from Washington, DC during the War of 1812.",
"Well there has been a theory floated around that the [Hekla 3 Eruption](_URL_0_) threw enough soot and dust into the air that the resulting change in temperature lead to several years of famine in Europe and the Middle East. These famines directly lead to the collapse of the bronze age civilizations, essentially reseting Western Civilization.",
"\"On September 29, 1717, an estimated 7.4 magnitude earthquake hit Antigua Guatemala, and destroyed over 3,000 buildings. Much of the city's architecture was ruined. The damage the earthquake did to the city made authorities consider moving the capital to another city.\"\nTaken from _URL_0_\n\n\nBasically a big earthquake caused Spanish officials to change the capital city from Antigua to what is now Guatemala City."
]
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[],
[
"http://en.wikipedia.org/wiki/Lisbon_earthquake"
],
[
"http://en.wikipedia.org/wiki/Year_Without_a_Summer"
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[
"http://en.wikipedia.org/wiki/List_of_epidemics",
"http://en.wikipedia.org/wiki/List_of_pandemics",
"http://en.wikipedia.org/wiki/Great_Famine_of_1315%E2%80%931317",
"http://en.wikipedia.org/wiki/Malthus",
"http://en.wikipedia.org/wiki/Great_Irish_Famine",
"http://en.wikipedia.org/wiki/Social_darwinism#Theories_and_origins",
"http://en.wikipedia.org/wiki/Small_Ice_Age#Depictions_of_winter_in_European_painting",
"http://en.wikipedia.org/wiki/Medieval_Warm_Period",
"http://en.wikipedia.org/wiki/List_of_natural_disasters_by_death_toll",
"http://en.wikipedia.org/wiki/Kamikaze_%28typhoon%29",
"en.wikipedia.org/wiki/Little_Ice_Age"
],
[
"http://en.wikipedia.org/wiki/Toba_catastrophe_theory",
"http://www.bradshawfoundation.com/stanley_ambrose.php"
],
[],
[
"http://www.guardian.co.uk/world/2010/apr/15/iceland-volcano-weather-french-revolution"
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[
"http://en.wikipedia.org/wiki/Minoan_eruption#Minoan_civilization"
],
[
"http://en.wikipedia.org/wiki/Sahara#History"
],
[],
[
"https://en.wikipedia.org/wiki/Hekla_3_eruption"
],
[
"http://en.wikipedia.org/wiki/Antigua_Guatemala#History"
]
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|
b0v5tc | how do photographers who print a lot of tourist photos make a profit if not everything they printed is sold? how does their business model work? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/b0v5tc/eli5_how_do_photographers_who_print_a_lot_of/ | {
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"Selling 1 photo pays for a LOT of unsold ones and people are more likely to buy something they can physically see in front of them then on a screen and then wait for it to be printed.",
"Printing them takes time, particularly drying time so that they don't smudge. You will sell more if the person doesn't have to wait 5 minutes when they are on vacation. If they sell them for $10 and they cost $.27 [ref](_URL_0_), then they break even at 1 out of 35 sales. "
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6l8aj6 | How did people precisely control the temperature of ovens for baking at specific temperatures? | Many very old baking recipes require ovens be kept to close to the same specific temperature such as 450^o or 375^o for close to an hour. How was this achieved with wood based fire ovens? How did people know when the fire was the right temperature and how did they keep it that way long enough to bake bread or a cake? | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/6l8aj6/how_did_people_precisely_control_the_temperature/ | {
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"A bake oven is a very big pile of masonry. Get all that thermal mass up to temperature, and it will fluctuate fairly little, and occasional stoking with a little wood can keep it hot. This is why baking was commonly done either by bakers, all day/night long, or by housewives one day a week: once the oven was hot, you wanted to make full use of it. The alternative for housewives was a Dutch oven, a deep covered cast-iron pot that could have coals placed on the lid, that could be used in the fireplace. But it couldn't do loaves of bread and pies as well as a bake oven.\n\nFor how to judge the oven temperature, here's what Lydia M Child said, in her *The American Frugal Housewife* :\n\n > Heating ovens must be regulated by experience and observation. There is a difference in wood in giving out heat; there is a great difference in the construction of ovens; and when an oven is extremely cold, either on account of the weather, or want of use, it must be heated more. Economical people heat ovens with pine wood, fagots, brush, and such light stuff. If you have none but hard wood, you must remember that it makes very hot coals, and therefore less of it will answer. A smart fire for an hour and a half is a general rule for common sized family ovens, provided brown bread and beans are to be baked. An hour is long enough to heat an oven for flour bread. Pies bear about as much heat as flour bread: pumpkin pies will bear more. If you are afraid your oven is too hot, throw in a little flour, and shut it up for a minute. If it scorches black immediately, the heat is too furious; if it merely browns, it is right. Some people wet an old broom two or three times, and turn it round near the top of die oven till it dries; this prevents pies and cake from scorching on the top. When you go into a new house, heat your oven two or three times, to get it seasoned, before you use it. After the wood is burned, rake the coals over the bottom of the oven, and let them lie a few minutes."
]
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cm3xvu | pcr's (polymer chain reactions) | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/cm3xvu/eli5_pcrs_polymer_chain_reactions/ | {
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"So it's been a while since I've done it but here goes : Think of DNA like a zipper. Pull the 2 sides apart and then cut the 2 single strands into chunks. With spare zipper teeth (ACTG) you can build 2 new strands, zip it back together and now you have 2 full zippers."
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||
40v454 | how do news agencies decide what is a national story? | News outlets seem to do a very good job at selecting what to cover and in effect controlling the dialog. On any given day there are thousands of possible news stories that could make it into the news. Some stories are obviously a given, like national disasters, big announcements by public figures or organizations, new statistics being released such as economic data, or major legislation. Others are far more spontaneous and seem to come from out of nowhere. Some stories seem to persist in the public conscious for a long time and be covered for weeks or months and make national history (e.g. OJ Simpson). Sometimes news stories result in the formation of national political movements like in recent years Black Lives Matter, Occupy Wall Street, and the Tea Party Movement.
Obviously many news organizations subscribe to wire services such as the Associated Press. But how and how do news agencies decide what goes out on the wire, what gets burried in local news or not covered at all? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/40v454/eli5_how_do_news_agencies_decide_what_is_a/ | {
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"Great question. The short version is that the news outlets have an editorial meeting every day or every shift to discuss ideas and assign reporting staff to the stories. Many stories come from press releases or public tips. Many more come from routine events, like a city council meeting, a parade, or a local business declaring its quarterly earnings.\n\nIn most places, the easier a story is to report, the more likely it is to be printed. Interstate closed for construction? Go talk to people for 20 minutes at a truck stop about how inconvenient it is. Story is done in an hour. Do another celebratory story when it re-opens. In both cases, the reporter is now free quickly to work on a more complicated longer-term story that may take a couple of weeks to put together.\n\nMainstream news is relatively unlikely to report on politically divisive topics, like a right to life march or a union rally because it might give ammo to those who shout \"The Daily Planet is pinko commie!\" Keeping in mind that The Daily Planet probably has no newspaper competition and has nothing to gain by being controversial.\n\nHow things generally get to \"the wire\": if something important is expected to happen, wire service staff reporters will already be there. If it is something more unexpected, like a mayor saying something nasty about Hillary, normally it will be reported by a local newspaper first, then sent to a regional or state wire editor, who may send it further to the national wire.\n\nSome national news outlets (Cable news in particular) have producers scour local news outlets to see if there were stories that never made it to the wire services that may still be interesting to their audiences. This is why a lot of times you'll see stories on talk shows like Greta Van Susteren or Rachael Maddow that don't get mainstream coverage.\n\nTL;DR: You have editors at every level who decide if a story is important enough to report, or to send on to a higher level editor for broader distribution."
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xa4ju | What would a tub full of viruses look like? | This is just a random thought I had, but say we had a clear plastic tub full of some ridiculous number of some virus bodies such that the only thing in the tub is them. Would it resemble some sort of protein goop or liquid and what would the color of said mass be depending on the virus? | askscience | http://www.reddit.com/r/askscience/comments/xa4ju/what_would_a_tub_full_of_viruses_look_like/ | {
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"text": [
"Hey there! I work with viruses, and this is what I can tell you: \n\nWhen we infect cells, we use vials of virus stockseed, which, depending on which virus you're working with, is essentially a purified suspension of virus that's been frozen and stored until it's needed for use. It's not 100% pure virus, which would be fairly unstable and hard to store. These vials of stockseed pretty much look like whatever media they were grown in - they often appear clear (as opposed to murky), and are the color of the media we use. \n\nOn the other hand, if I were to purify out virus from this solution, which I've also done before, it kind of looks like an off-white colored, thick gloop at the bottom of the test tube.\n\nThat's just personal experience, though, and I imagine it differs with different viruses. ",
"Viruses can be crystallized, which might get you a better idea about what color they are. All the pictures I've seen of virus crystals have been transmitted-light or electron micrographs, so I have no idea what they look like by reflected light."
]
} | []
| []
| [
[],
[]
]
|
|
1vzatt | if websites like youtube can shorten their url for "sharing" purposes, why can't the url just naturally be shorter? | This also goes for any other websites with long URL's seeing as how there are places where you can shorten the link significantly. | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1vzatt/eli5_if_websites_like_youtube_can_shorten_their/ | {
"a_id": [
"cex7nja",
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"text": [
"Taking Youtube as an example, if you actually pay attention to what is in the URI, you might see that this is where different options are passed about what you want to see. For example, if you watch a video and decide to send a link to someone which starts at a certain timestamp, you will get slightly different text with something like \" & t=105s\" added into the last section. The number of combinations of options is huge and creating a unique string for each and every one which will still work in a somewhat distant future means storing all of the links anybody has ever made. It also means looking up that extra information every time somebody wants to see anything at all, which isn't free (although not very expensive). Also, it would require extra steps for third-parties who are comfortable editing the URI string themselves to get that converted into an encoded, shortened URI every time they need to make a link which may, possibly be clicked.\n\nThey could do it, sure, but except for people sharing links in very special formats such as Twitter, there isn't really much reason to and there are some annoying costs associated with it.",
"To be fair with Youtube - they're not really shortening/altering it that much.\n\nSay you want to share:\n > _URL_7_\n\nWhen you press the share button, which shortens the link for posting wherever, you only end up with:\n\n > http://_URL_0_/dQw4w9WgXcQ\n\nAll that happens is they switch the domain to \"**_URL_0_**\" (saving 3 characters) and loose the \"**watch?v**\" bit (saving 7 characters).\n\nBut, if you go to the _URL_0_ link you just get redirected to the _URL_3_ video. It's just a link.\n\nI think the main reason this isn't more common with other sites is:\n- Not everything has an easy link structure (Reddit's for example) that can be condensed down to shorter links and still properly communicate where you're going/retain your brand.\n- In YouTube's example, it required them registering another domain in Belgium.\n- If they really need a short link they can use services like [_URL_5_](_URL_2_), [_URL_4_](http://_URL_4_/) or [bitly](_URL_6_). If you look on Bitly's homepage they do claim a number of well known brands as clients.",
"One reason is that long (and human readable) URL's are a part of search engine optimization (SEO), because URL's containing keywords from the content of the page tend to be ranked better than just random looking ones. Youtube is not a very good example for this though, because even the regular URL's are not human readable (but being owned by Google is probably much more significant in the search engine ranking anyway ;)\n\nAnother reason is usability. It's much easier to remember (and tell someone about) the URL \"_URL_0_\" rather than \"compa.ny/93HkdI1\" and if you happen to see such an URL you can more or less tell where the first one will lead you to when you click it, but not with the shortened one. You probably wouldn't open \"_URL_1_\" at work - but who knows if \"compa.ny/93HkdI1\" is actually safe for work or not? \n\nAnd last but not least, when using a URL shortening service out of your control: What happens if for example _URL_2_ goes bankrupt? all the links using that service are down and there is no way to tell or recover the original content behind that link.\n\nIn my opinion, shortened URL's are fine for Twitter and other services where available space is an issue, but usability and transparency for the user suffers pretty much.\n\nEDIT: some typos."
]
} | []
| []
| [
[],
[
"youtu.be",
"http://youtu.be/dQw4w9WgXcQ",
"http://goo.gl/",
"Youtube.com",
"ow.ly",
"goo.gl",
"https://bitly.com/",
"http://www.youtube.com/watch?v=dQw4w9WgXcQ",
"http://ow.ly/"
],
[
"company.com/products/whatever",
"company.com/products/huge-fuckass-dildo-with-demo-video",
"bit.ly"
]
]
|
|
602s6d | how come when having a sickness that requires medicine, i have to do it in a span of a week or a few days? | Why can't I ingest it as much as I can? Wouldn't the sickness be cured faster when doing so, following common sense? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/602s6d/eli5_how_come_when_having_a_sickness_that/ | {
"a_id": [
"df31k06"
],
"score": [
15
],
"text": [
"Accomodating the poor English, are you asking why you can't take the whole course of medication at once?\n\nLet's use the antibiotic 'Gentamycin' for example. The drug is not easily filtered out by the kidneys, and an overdose would cause the kidneys to not work. That results in kidney failure and you'd potentially die.\n\nDoses are often set to what is safe. "
]
} | []
| []
| [
[]
]
|
|
400x08 | Do we believe the figures for Ancient Battles? | It would be useful to know: What's the consensus on the believability of the figures for ancient battles?
For example, Zosimus has Palmyra fielding an army of 70,000 in the AD270s. (_URL_0_ search for "seventy")
That's roughly the same size as the French army at Waterloo.
Do we believe these figures? Divide them by 10? Ignore them as just meaning "Lots"?
Much gratitude in advance....
(As a writer, I'm not adverse to epic battles, but I also live in fear of being Obviously Wrong.) | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/400x08/do_we_believe_the_figures_for_ancient_battles/ | {
"a_id": [
"cyqmvjl"
],
"score": [
7
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"text": [
"This topic, depending on the battle, can be hotly debated among historians. Occasionally archeological evidence can shed light on the battles, but often historians must defer to the written record. That said, most historians won't take the figues exactly at face value. If the army in question is Egyptian, there may be less available. The point I am trying to make is that the written record should not be completely thrown out just because numbers are inflated, nor typically is it. There are certainly historians who do that, however for the most part the written record is trusted until there is something that brings it into question. \n\nWith Caesar, often times there are so many sources showing both sides that historians can typically discern a fairly reliable timeline. With figures, it is best not to throw out evidence simply because there may be bias. Every historian is biased in some way and that is not necessarily a bad thing. It can potentially provide a balanced account, if paired with others. Unfortunately, if (such as in the case of Zozimus) that is the only account of that battle, it can't be thrown out simply because the facts may be skewed due to bias. If a source is to be doubted, there needs to be more than that. If there were, say, archeological evidence, or other written evidence showing that this could be reasonably questioned, then it could be doubted. \nTL;DR The rule of thumb for most historians is \"innocent until proven guilty\".\n\nPurely historically speaking, I think it is entirely likely that Zozimus had the numbers correct. The ancient mediterranean world was quite populous. Rome had at this time a population of 1,000,000. Alexandria had a population of 500,000 (both roughly speaking). Palmyra was a major trade hub and It absolutely could have afforded an army of that size. Armies of this size were not that uncommon, either. For much of Rome's history the entirety of the army consisted of about 300,000 legionaries. By the late empire (when Zozimus is writing), it is believed to have tripled. This meant that the Romans could absolutely have brought massive amounts of man power to bear, and since Palmyra was actually able to defeat Rome once, it had to have a sizeable army. For more info on the Roman army at this time, check out Arther Ferrill's book \"The Fall of the Roman Empire: The Military Explanation\". \nHope this helps!\n\nEdit: I have removed some information which Iphikrates indicated was actually false. "
]
} | []
| [
"http://www.tertullian.org/fathers/zosimus01_book1.htm"
]
| [
[]
]
|
|
196dsv | relative to the size of time and space today, how big was the dot of condensed matter before the big bang. | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/196dsv/relative_to_the_size_of_time_and_space_today_how/ | {
"a_id": [
"c8l9huo",
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"score": [
4,
2
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"text": [
"First off, \"before\" the big bang is an absurd qualifier. Time, space and possibly causality too, originated at the big bang. Asking what happened \"before\" that is like asking what's north of the north pole - in other words, a statement so absurd that it's [not even wrong](_URL_0_).\n\nBut, to answer your question, currently prevailing theories place all matter-energy in a singularity of infinite density. Its volume would be infinitesimal - which is to say, smaller than anything you care to think of.\n\n",
"There was no \"dot\" of condensed matter. This is a common misconception. At the moment of the Big Bang, space was extremely dense, but it was still infinite in size."
]
} | []
| []
| [
[
"http://en.wikipedia.org/wiki/Not_even_wrong"
],
[]
]
|
||
76ij08 | if our body focused on preventing telomere reduction, what changes might our bodies experience? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/76ij08/eli5_if_our_body_focused_on_preventing_telomere/ | {
"a_id": [
"doe9eqh",
"doeabno"
],
"score": [
5,
6
],
"text": [
"To prevent telomere reduction, your cells have to stop dividing. If you meant regenerating telomeres, I don't have the answer for that",
"Cancer. Cells continuing to divide with no limit is called cancer.\n\nIf you mean instead \"what would happen to us if our bodies focused on sustaining cells /efficiency as long as possible before natural cell death what would happen?\" Is a much more interesting question."
]
} | []
| []
| [
[],
[]
]
|
||
ajce0s | what is the difference in propaganda and fake news | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/ajce0s/eli5_what_is_the_difference_in_propaganda_and/ | {
"a_id": [
"eeubao7",
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"score": [
3,
3,
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"text": [
"Well, one thing to be cautious of, is that 'fake news' is thrown around with relative abandon today, even against news that is not, in fact, fake *or* propaganda, merely which contrasts against the viewer's given preference. \n\nSo in some ways, it is simply a slur against the reporting organization. \n\nIn cases where 'fake news' is actually fake news, I would say in some cases it can be synonymous with propaganda. A more precise definition may (but won't necessarily) distinguish propaganda as news with bias, selective reporting, or other techniques to slant the opinions of people reading it, versus fake news making up false information altogether. In other words, distorting the facts, versus making your own. ",
"There isn't a hard line between the two notions.\n\nHowever, propaganda is normally construed to be centrally directed to sell a narrative. Pravda was propaganda because it was the official mouthpiece of the Soviet Communist Party - all of its 'news' stories were written primarily with an eye towards presenting the party in the best possible light.\n\nOn the other hand, 'fake news' is more de-centralized, where the bias of individuals creates a tendency towards selecting and perceiving stories in a certain way that paints a false picture.",
"Propaganda is not necessarily false.\n\nIt's normally split into \"white\", \"gray\", and \"black\" propaganda.\n\nWhite propaganda is entirely truthful, although usually selectively truthful.\n\nBlack propaganda is simply false and deceitful.\n\nGray propaganda mixes truthful and deceitful elements.\n\n\"Fake News\" is usually gray propaganda (e.g. Hillary Clinton did cough and hid her pneumonia from the public but she wasn't about to die) or black propaganda (Obama was not born in Kenya).\n\n & #x200B;"
]
} | []
| []
| [
[],
[],
[]
]
|
||
bwc53q | Did the Strategic Defense Initiative Real aka "Star Wars" really help Bankrupt the Soviet Union ? | edit: typo in the tittle, sorry.
I've often heard it parroted that the Soviet response to the SDI and ensuing economic pressure helped hasten collapse of the USSR. Is there any truth to this? What was the Soviet's response to the SDI? | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/bwc53q/did_the_strategic_defense_initiative_real_aka/ | {
"a_id": [
"epwjgg2",
"epwjobc"
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"score": [
21,
10
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"text": [
"No. This is a post-Cold War myth, written largely by people who would like to make SDI not appear to be the boondoggle it was, or to make it look like something that had a positive effect on diplomacy, rather than the more easily-documentable negative effect. Pavel Podvig has [written at length about this here](_URL_1_) and [here](_URL_0_).\n\nAside from being asserted without evidence, I would just note that the fall of the USSR was clearly caused by many factors, most of them internal: Gorbachev's attempts at opening up the system very clearly and directly led to its instability and failure. While the Soviet overexpenditure on arms (in general) no doubt did not help its overall economy, the idea that its collapse can be traced to that, much less to a specific US program which the Soviets did not in fact respond to, is facile.",
"I'll shamelessly plug an [answer](_URL_0_) to this very question that I wrote, but basically....what u/restricteddata said."
]
} | []
| []
| [
[
"https://thebulletin.org/2013/04/shooting-down-the-star-wars-myth/",
"http://scienceandglobalsecurity.org/archive/2017/01/did_star_wars_help_end_the_col.html"
],
[
"https://www.reddit.com/r/AskHistorians/comments/8cnm73/did_reagans_star_wars_project_really_contribute/"
]
]
|
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