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aufvdf | how do ice cream shops adjust their business models to survive the winter months? | [deleted] | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/aufvdf/eli5_how_do_ice_cream_shops_adjust_their_business/ | {
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"Sometimes you have to save money from the busy season to cover the slow season. Just like a farm only makes money at harvest the rest of the week year it's off of savings from the sale of the harvest. \n\nCut down on inventory, reduce labor are options"
]
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b5n68s | is a heavier vehicle (truck) or a lighter vehicle (empty truck) able to stop quicker? (momentum/weight = more traction?) | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/b5n68s/eli5_is_a_heavier_vehicle_truck_or_a_lighter/ | {
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"Two identical trucks, each weighing 10,000 lbs empty, and one loaded with an additional 10,000 lbs of cargo - the empty truck will stop quicker. There is simply a lot less mass to decelerate. Force is simply mass x acceleration (in this case deceleration, which is just acceleration in the opposite direction). So F=m\\*a. Applying identical brakes fully produces the same force on each truck, so F stays the same. Rework the equation and you get F/m=a. The loaded truck is 2 times as massive as the empty truck. The equation can be reworked for the loaded truck to F/2=a(heavy) and for the empty truck it's F/1=a(empty). So the same stopping force is literally half as effective at stopping a truck that's twice as heavy.\n\nDoes friction come into play? Sure, but not anywhere near enough to overcome the disparity in mass, even if the loaded truck were 10% or 20% packed rather than fully loaded. At that point, road conditions, tire tread, etc. are far more significant factors, and if all those were controlled for and equalized, the heavier truck would always need more force to slow it down when compared to the lighter (but otherwise identical) truck.",
"If we assume that the driver is slamming on the brakes (effectively locking them, getting the maximum possible deceleration from friction of the tires with the road), and in both cases that happens simultaneously, the stopping distance is the same.\n\nThe force caused by friction on the same surface (i.e the same coefficient of friction) varies directly with mass. Double the mass, double the force of friction. Which is important, because the quickness of stopping is determined entirely by acceleration and a =F/m.\n\nThe force of friction is F = μ*η which is the coefficient of friction times the normal force.\n\nOn a flat road, η = m*g, or mass * gravity.\n\nSo, in total our equation would be:\n\n(μmg)/m = a\n\nRight away you notice that the \"m\" cancels, mass is irrelevant. but we can do it anyway.\n\nlet's take 1,000kg and 500kg because we're talking mass.\n\n(0.7 * 1000kg * 9.8m/s2) = 6860N (newtons).\n\n6860N/1000kg = 6.86m/s2 (the acceleration caused by friction)\n\nNow let's try the 500kg\n\n(0.7 * 500kg *9.8m/s2) = 3430N\n\n3430N/500kg = 6.86m/s2.\n\nEssentially, because mass shows up both as part of calculating force and as something you divide force by to get acceleration, doubling, halving, or otherwise interacting with mass cancels itself out.\n\nWhich is why the actual calculation for stopping distance doesn't include it:\n\nd = V^2/2fG\n\nIn English the distance is the initial velocity squared divided by 2 times the coeeficient of friction and the acceleration due to gravity applicable (on a flat surface, 9.8m/s^2)",
"It really depends on lot of things. I think empty trucks will stop faster than full truck. Full truck have lot of kinetic energy.\n\n Difference in friction of empty and full truck is not as significant in a well paved dry road. \nIf its not paved or dry road or in a slope, cant really tell without specific details."
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f4kyz | Does living in the city have an effect on the immune system? | I have to admit that my knowledge about our immune system and how it can change is close to zero.
Does living in the city have an effect on the immune system? Positive or negative?
I'm thinking mainly of living in the inner parts of a city in the Western world, say, a European capital, with a fair amount of car traffic. Would that take its toll on a person, or can it be beneficial? | askscience | http://www.reddit.com/r/askscience/comments/f4kyz/does_living_in_the_city_have_an_effect_on_the/ | {
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"There are a lot of factors influencing this. You're thinking about car traffic and pollution, but there are other things such as close proximity to many different people that affects your immune system as well.\n\nWith regards to pollution, you'd probably be looking at one aspect of your immune system: allergies. You produce IgE antibodies against certain allergens in the air. When you get exposed to smog or dust (or other things like pollen, cat dander, etc) consistently, your body will react to it and attempt to remove it by inflammatory methods which will cause you irritation. So, you might get inducible asthma from constantly breathing in smog.\n\nSo, short answer is, living in the city has a neutral effect on your immune system because it'll just be doing its job, but your immune system's effect on you will be slightly negative because you'll possibly be irritated. But, this itself will be no different than if you were to have allergies to tree pollen and living in rural areas.\n\nThe thing you need to worry about (if anything) is the small carcinogenic effect of whatever smog you breathe in from car exhaust. Truthfully, it will have the same (or even less) cancerous effect than if you were to stay outside and get sunburned often.\n\nNow, if you were to look at your increased chance of interacting with random people (subway, streets, etc), then you will see an increased effect of getting sick. Your immune system, again, is just doing its job, so city interaction won't have a positive nor negative effect on it.\n\nReally, there's little you can do to affect your immune system negatively: contract HIV, start chemotherapy, absorb no vitamins, etc. Living in a city will probably have a negligible effect on your immune system's ability to function - you'll just have to suffer through when your immune system does its job."
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4bf869 | how does the flu virus adapt every year so that our body can never fully prevent it from happening? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/4bf869/eli5_how_does_the_flu_virus_adapt_every_year_so/ | {
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"Think of it like a plant, there can be multiple strains of the same plant, but they arent the exact same, but in their base, they are the same, hence being the same species. It is very similar in the flu. There are different strains of it, which all mutated off of the original strain at some point. Scientists look at past records and take guesses at which strains will be prevalent during a given year, and this is how they choose what vaccines to use, and unfortunately since there are so many possible strains, scientists get it wrong sometimes, and the vaccines arent as effective as thought."
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7mfdjo | why can we not just drain the energy/radiation from uranium rods so that they are not as deadly when we dispose of them/store them? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/7mfdjo/eli5_why_can_we_not_just_drain_the/ | {
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"Because the rate at which the energy is released is not under our controlled. It is rooted in fundamental constants of the universe and we have no way of changing it.",
"So you need to have some basic concept of what this stuff is. All stuff (matter) in the universe is made from essentially 3 main components (protons, neutrons, electrons). What makes different things different is the combinations of those three stuffs, but also the size (atomic weight). Here's the thing, because of the fundamental nature of the universe, atoms don't want to really be over a certain weight (Starting with atomic weight 83 on the periodic table). It's too much. If you go over that weight they start to rip themselves apart, creating new atoms in the process and releasing energy. The heavier over that certain weight you go, the more energetic, and the faster that process is. We can't stop it. It's just the way the universe is. Once that stuff gets heavy enough it will decay according to its half life the same as an apple will fall from a tree or oil will float on water. The mechanism is not under our control. "
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y6t1x | What causes a filled water bottle to 'recoil' when it is being emptied? | By being emptied, I mean turned so the neck is facing the ground.
What are the physics behind the 'recoil'? | askscience | http://www.reddit.com/r/askscience/comments/y6t1x/what_causes_a_filled_water_bottle_to_recoil_when/ | {
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"text": [
"Can you expand on what you mean by recoil?\n\nIs it when you turn a full bottle upside down, how it empties in bursts and when a burst finishes, the bottle raises slightly?"
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uliik | - why does 9 * 1/9 not equal 1? | So 1/9 = .1 repeating. Times that by nine gives .9 repeating. But 9/9 equals 1.
Please, ELI5. | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/uliik/eli5_why_does_9_19_not_equal_1/ | {
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"It does. .9 repeating equals 1.\n\nIf you don't believe me, consider this. Any numbers that aren't equal must have some nonzero difference, right? So if 1 and .9 repeating aren't equal, what is the nonzero value of 1 - .9 repeating?",
"Amarkov is right but let me try to make it a little more LI5.\n\n.9 repeating is the same thing as 1. It is the same because there is no difference between them. If you were to try and subtract them you would get .0 repeating and then a 1. If I were to write this out then no matter how long you gave me to write it I would never get to the 1. I would just have a bunch of 0s so no matter how careful you want me to be I would still only have written 0. That means there is no difference between .9 repeating and 1.",
"Decimal notation and fractional notation are different ways of representing numbers, each of which have their own advantages and disadvantages. Fractions don't always neatly translate into finite decimals. Some fractions have an exact and straightforward decimal equivalent, like 1/4 is 0.25. Whether or not a given fraction will have a short decimal equivalent depends on whether it is a multiple of, or a whole factor of, 10. Numbers such as 1/9, or 1/3, happen to have to be represented in decimal notation as infinitely repeating digits: 0.111..., and 0.333..., respectively. Infinitely long chains of repeating digits are not especially convenient to work with, and they are a little conceptually weird, but they are actually the same number as their fractional representations.\n\nEdit: Came up with an ELI5 analogy: Imagine that I have a piece of cheese, and you and me and Joe Bob want to share it equally between us. Easy peasy: we cut it into three equal pieces, and now we each have 1/3 of the original cheese, or one piece out of the three pieces we cut the original cheese into. Yay for snacks and being good sharers! \n\n But the next day in the cafeteria, it turns out that I brought 3 pieces of cheese, you brought 4, and Joe Bob brought 3: 10 total pieces of cheese. And, again, since we're totally, like, bffs, we want to share our tasty cheeses equally. So we each take 3 pieces, and we're about to cut the remaining piece into neat, even thirds, when [my analogy kind of breaks down at this point, so I have to introduce a little *lunchlady ex machina*] the cafeteria monitor rushes over, takes our knife away lest we injure ourselves, announces a new rule that all pieces of cheese must be cut into ten pieces or not cut at all, and chops our last chunk of cheese into ten small bits. \"Goshdarnit,\" we all say, with a silent thrill at our temerity in using this potent expletive, and again each take three of the ten bits, again leaving one bit left over, which again that meddling lunch nanny splits into ten tiny cheese dots. Taboo and verboten words like cr*p flit across our guilt-ridden minds, but with pluck and foreboding we each once more select three cheese dots... leaving one cheese dot left over, as an agonizing test of our bffness. Bound by the ancient and inscrutable commands of kindergarten bffity, we furtively reach for the cheese dot, hoping to surreptitiously divide it evenly into neat, clean, simple thirds before our unexpected nemesis, that insufferable martinet of a lunch lady, can swoop in and threaten our peaceful tripartite friendship with another iteration of the intractable problem of dividing ten discrete things into three equal wholes. We fail; she swoops; cheese dot becomes cheese fragments. Intrepid, stubborn, foolish - above all devoted to the high ideals of bfferosity - we repeat the cycle forever, always getting three more, smaller, pieces of cheese each, and always having to watch the tenth bit be split into ten still smaller bits - but, gratifying our deep bff desire to share all things equally, always approaching more and more closely a perfect and exact division of our original ten cheese sticks into three even piles.\n\n**TL;DR** Yeah, I got kind of carried away by my gripping narrative. Ten things can't be broken evenly into three stacks, particularly if the individual things can each only be split into ten smaller things; which is how decimal notation works, and which is why rendering simple fractions in decimals sometimes has to make use of the non-intuitive concept of infinitely repeating digits.",
"Amarkov is right.\nThe biggest hangup, I think, that people have with this is that people have it absolutely drilled into their mind, for whatever reason, that any number must have exactly one decimal representation. This is completely false, and there's no reason to believe it's true other than that it's maybe implied when they first teach you about decimal notation in elementary school, or at least it's not made explicit that it is false. Some numbers in decimal notation have two representations—that's just a particular property of decimal notation. The number 1 actually has infinitely many representations: 1, 2/2, π/π, e0 , ln(e), √1, etc. 0.999... is just one of the two ways that we can represent the number 1 in decimal notation. 1 isn't unique in this sense—lots of numbers have two decimal representations: 0.2=0.1999..., 0.25=0.24999..., and so on. And that's just fine. It doesn't break math or decimal notation, it's not a weakness of decimal notation. It's just a property of this particular way of representing numbers.\n\nA nice proof that 0.999...=1 goes like this: Let x=0.999... . Multiply both sides by 10 so that you have 10x=9.999... . Subtract x from both sides to get 9x=9. Divide by 9: x=1.\n\n**EDIT** I would add that your question is actually also a proof that .999... = 1.",
"I used to break my head over this as well, until someone asked me this:\nwhat would you add to 0.9999... to get to 1? There is nothing you can add, because it keeps repeating. Thus you'll add 0.000...\n\n0.9999... and 1 are the same.\n"
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1493ky | why does overvolting make overclocking more stable? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1493ky/why_does_overvolting_make_overclocking_more_stable/ | {
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"This subject is way too complex to ELI5. But here's a source that actually explains how the innards of a processor work.\n\n_URL_0_\n\nEssentially the increase in clock speed requires a higher threshold voltage for the tiny digital switches in the processor to keep up.\n\nYou might want to try one of the EEs over at /r/askelectronics, they'll have a better understanding of the details and might have more experience explaining it.",
"First let's answer the question \"Why can't I run my processor faster than I am now?\". There can be various factors that come into play, such as how hot it is getting. But the key one is \"timing margin\". \n \nFor the circuits in a processor to all work together, it requires that the output of each circuit to be in the correct 0 or 1 voltage \"state\" before it is needed for the next circuit's input downstream. System clocks help keep this all running smoothly, telling each logic gate when it is OK to depend on its inputs to all have reached their proper values, kind of like a drill sergeant calling out a cadence for troops to march to.\n \nIt takes a finite amount of time for a circuit to switch 0- > 1 or 1- > 0 and have that value reach the next gate. It also takes a certain amount of time for a gate to respond to changes to its input. If the timing, as run by the clock, doesn't allow for enough margin between the output of one gate and the input of the next, errors happen. We call that the \"timing margin\", and if it becomes negative, then failures are likely. \n \nWhen you speed everything up (running the clock faster), its like the drill sergeant starting to call things out faster and faster, leaving less margin for error. Eventually someone kicks someone else's feet and bad stuff happens. \n \nBUT....if you increase the supply voltage, it effectively makes the transistors' states switch faster and get valid 0/1 voltage levels to the next gate downstream faster. So if you apply a higher voltage, you can run the clock a bit faster, since you now have a bit more timing margin to work with. \n \nEventually, you get to a situation where increases in the power supply voltage don't give much extra speedup, or you run into a circuit that isn't as voltage sensitive as the rest, or the part starts using too much power and gets too hot. Then you've reached the overclocking limit for that part. ",
"We like to think of computer signals as being on or off, 1 or 0, but the reality is a little more messy, especially the faster you switch back and forth. On might be 1.5v and off might be 0v, but eventually you are only getting down to 0.5v and back up to 1.0v and the hardware doesn't know which one is which.\n\nIncreasing the voltage gives your hardware a little more room to work with."
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lcpjn | oxytocin and its role in pair-bonding in human sexual relationships | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/lcpjn/eli5_oxytocin_and_its_role_in_pairbonding_in/ | {
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"Happy to explain this one but I'll need you to be a bit more specific about what you want to understand. Are you asking the how or why?",
"Happy to explain this one but I'll need you to be a bit more specific about what you want to understand. Are you asking the how or why?"
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1nv5wr | How accurate were maps at the start of the 19th century? How much did the accuracy of maps improve after spy satellites could see exactly what the world looked like? | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/1nv5wr/how_accurate_were_maps_at_the_start_of_the_19th/ | {
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"Map historian (among other hats) here. We need to define \"accuracy\" before we can really talk about relative terms; all maps are representations, so the accuracy is a subjective thing connected to the use of the map. It's already a spheroidal object put on a flat plane, so major concessions to geographical fidelity already exist. Do you mean in terms of physical geography only, human geography, or something else? If you start asking about names, labels, and descriptive terms, then the subjectivities multiply in myriad ways--and it matters where on the Earth you're asking the question regarding.\n\nPrecision itself (and thus \"accuracy\") depended on the ability to have a positional fix for mathematical regularity. For that, you needed networks of geodetic triangulation, knowledge of astronomical positions, and so forth, by which you can eventually devise a model of the Earth's actual shape (it is not a perfect sphere, or even a perfect flattened sphere) and place points upon it with accuracy for your purposes. At the start of the 19th century, there weren't a tremendous number of such arcs, so gross errors (and in the case of many areas, like deep continental interiors, no information at all) were fairly widespread. The coast was easier to rely upon--charting bearings, coastlines, and navigational hazards preceded systematic, precise interior mapping almost everyhwere, and then could be corrected--but you will see a lot of wonkiness in maps throughout the 19th century. The [Perry-Castañeda map collection at Texas-Austin](_URL_1_) has a lot of beautifully scanned examples of such maps, such as [this one from 1820 on the Mercator projection](_URL_0_). The gaps, missing pieces, and sort of impressionistically drawn rivercourses give you an idea of where the mapmaker went into a fully artistic mode of rendering. The materials a cartographer worked with up into the 20th century also included a lot of maps by other people, which could be of varying reliability. Mathematical data was preferable, but sometimes material was vague or even merely textual and so features (including names of people, towns, et cetera) outside of the area of consumption could be completely wrong and nobody would actually know.\n\nPrecision became much better with the rise of aerial survey, satellite imagery, and now with GPS built on systems of satellite and ground-based reconciliation to reduce error by constant reconcilation. In some places it's a matter of changing three inches of positional error to one-half inch, but in others (like Francophone Africa) the maps are still virtually useless for anything other than broad planning despite apparent precision, and Google Earth is actually more reliable. So within the industrial world, the rise of satellite imagery may have permitted a more invasive but comprehensive rendering of human and physical geography, but not a gross improvement in precision; in the so-called \"Third World,\" a lot of mapping is simply impossible without it. Our idea of what constitutes an accurate map has also changed because of this surfeit of mathematical data. Our standards are arguably much more stringent, even if the precision on the map is illusory or irrelevant.\n\n[edit: wording, too many semicolons, ugh]"
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ev4j8j | Did Pre-Columbian Native Americans Have Cauldrons? | This is going to sound a bit weird, so please bear with me. I was reading up on [Irish stew](_URL_0_) and noted the idea that cauldrons as a cooking technology weren't introduced to Europe until relatively late.
So this makes me curious about pre-European contact Native Americans. I know metalwork was limited on the continent so metal cauldrons per se probably wouldn't have existed, but I also know they made stone bowls and whatnot - did Native Americans have a tradition of cauldron-style cookery? Or was this a less obvious part of the Columbian exchange? | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/ev4j8j/did_precolumbian_native_americans_have_cauldrons/ | {
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"So, are you asking whether Natives made soups and stews, or whether natives used metal cookware for them specifically?\n\nThe first answer is quite easy to answer. In both the Triple Alliance and Inca Empire, soups and stews were cooked, seemingly in earthenware or pottery. The Triple Alliance examples come to us via Spanish accounts in the Codices. The *Florentine Codex* mentions Pozole specifically, which has now evolved to become a national dish in Mexico. The Inca diet was more varied due to the vast geographical area they covered, and was largely vegetarian due to the limited availability of meat livestock. However, *Last of the Incas* by Kim McQuarrie makes mention of Inca fish stews being eaten on the coast.\n\nIt also stands to reason, as a soup or stew is the simplest food one can prepare. Boiling water maintains a consistent temperature during cooking, and so alleviates variation in temperature methods like baking, roasting or frying would contend with on primitive fires."
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"https://en.wikipedia.org/wiki/Irish_stew"
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thwot | what causes tattoo ink to stay in skin, when we are constantly shedding skin flakes? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/thwot/what_causes_tattoo_ink_to_stay_in_skin_when_we/ | {
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"The ink is injected much deeper in the skin. You usually lose the first few layers of skin, the ink is injected into the deepest layers of skin.",
"There are a few layers of skin on your body, the tattoo gun injects the ink under the first layer of skin because that layer doesn't shed, and if the needle gets too deep into the skin it begins to smear and bleed out.\n\nSource : My father is a tattoo artist. ",
"Ink injection causes an immune response in the dermis. Phagocytes consume the ink, and later, fibroblasts induce dermal scarification, which creates a collagen network to hold the phagocytes in place."
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1wu5cr | Cats were originally domesticated because they kill vermin, and dogs were useful as guards and for hunting. They helped take care of us. In modern times, we completely take care of our pets. They're our family instead of our tools. When did this change? | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/1wu5cr/cats_were_originally_domesticated_because_they/ | {
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"I wouldn't say they aren't useful tools to the family. Put a couple cats in a warehouse and see all the vermin disappear. Likewise, let your cat in the garage and see that annoying mouse disappear forever. And of course, tons of people own dogs that alert the house for intruders, to say nothing about police and military attack dogs or service dogs.\n\nIf you're talking about when dogs and cats strictly became pets, it likely originated with the rise of civilization and likely began with the aristocracy who did not need pets to be guards/hunters as they had servants and peasants to do it for them."
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28cemx | Why does air blow in the back windows of a car and out the front? | If you open the driver side window and the diagonally opposite window equal amounts, the air will flow in the back window and out the front window regardless of how much your open them or the order you open them in. I imagine it has to do with the turbulence around the car, but I'm not really sure. | askscience | http://www.reddit.com/r/askscience/comments/28cemx/why_does_air_blow_in_the_back_windows_of_a_car/ | {
"a_id": [
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"Air will flow from high pressure regions to low pressure regions. If what you say occurs, then it must be because the air pressure outside your rear window is higherr than the air pressure outside your front window.\n\nAir flow around a car is turbulent and complex, so what you observe on your car isn't necessarily true on other cars. It may also depend on the speed of your car. You might get a different effect on your car at different speeds."
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2fcuru | trading gold and silver commodities | I am trying to get into the commodities market and I need more knowledge. | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2fcuru/eli5trading_gold_and_silver_commodities/ | {
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"text": [
"If you are putting money on the line, I wouldn't bother with ELI5. Go ask this question in an investing community (maybe [r/PersonalFinance](_URL_0_) would help you?).",
"If you don't have even a 5 year olds level of understanding then why do you want to get into it? If you are actually interested then I can explain some of it, but you won't make money, trust me.",
"\nWhen you buy a commodity you are buying a piece of paper (now virtual) that says \"This guy owns x amount of y commodity.\" You don't get the physical substance mailed to your house. If you want to sell it, the paper goes to somebody else. You don't need the physical commodity because it is completely interchangeable with any other instance of that good (this is what makes it a commodity, it's called fungibility). An ounce of gold is an ounce of gold is an ounce of gold, the same way a bushel of corn is a bushel of corn.",
"You have come to the wrong website."
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dir5k6 | What's the difference between relativistic quantum mechanics and quantum field theory? | askscience | https://www.reddit.com/r/askscience/comments/dir5k6/whats_the_difference_between_relativistic_quantum/ | {
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"To put it simply, a quantum field theory is a quantum theory that is both:\n\n1. Relativistic, and\n\n2. Allows for creation and destruction of particles.\n\nThere also exists relativistic quantum mechanics without particle creation/destruction. This would be like solving the Dirac equation for a system with one electron.\n\nAnd there are also quantum theories where particles can be created and destroyed, but aren't relativistic. This is often referred to as \"second quantization\", and it's useful in atomic or nuclear physics, where relativistic effects aren't necessarily important.",
"Relativistic quantum mechanics is an attempt to take a wave-like theory that associates a single particle with a single quantum wavefunction and tries to come up with the \"rules\" for how such an object should propagate in time such that it is consistent with special relativity.\n\nThe, sorta, \"toy\" way the issue with this is often illustrated is in terms of energy-time uncertainty. A quantum state in RQM has an uncertainty in energy that is not absolute but is dependent on the time frame over which a measurement is carried out. At the same time the famous result of SR is E=mc^2 and that matter and particles can be created with sufficient energy. This at least... motivates... the notion that if one tries to construct RQM the \"particle content\" is actually not absolute but dependent on measurement time and yet RQM is the story of a single wavefunction evolving in time.\n\nThis is simply irreconcilable and thus RQM fails. In QFT one abandons QM and goes back to classical theory and then quantized in a different way arriving at a quantum field where particles are excitations of those fields. Here the issue goes away."
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1u14bn | How would a guaranteed income affect inflation? | There has been a lot of talk recently -- especially in /r/futurology -- about the prospect of implementing guaranteed income in the US. Many people have called for it, and other countries seem to be having success with similar programs (See: _URL_0_)
I agree with the basic premise of the guaranteed income, but to me it just seems logical that if you increase the income of every citizen, it would just lead to inflation that would essentially offset this increase.
In other words, people living off of the minimum/guaranteed income would be essentially as poor as they were prior to its implementation because prices would increase.
Is this true? Or would this actually help to lift people out of poverty? | askscience | http://www.reddit.com/r/askscience/comments/1u14bn/how_would_a_guaranteed_income_affect_inflation/ | {
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"Hey I read your links and read through the answers here. I don't think any answers here are satisfactory.\n\nSo there are a few things to address here. First I want to clarify what inflation is. Second I'll address methods of wage redistribution to create this guaranteed income. Finally i'll talk about the implications of guaranteed income on inflation. Periodically I'll be hitting submit then editing so that way I don't lose what I've typed. (no longer applicable as I am finished now)\n\n > **Inflation**\n\nInflation describes the ratio of money to (Goods+services) in the economy. I put goods and services in brackets because they are generally handled as one thing. First, the **ratio**, that money for goods, is called price. The common index used to track changes in this ratio is the CPI. It tracks a core bundle of goods and how many nominal dollars it costs. As price levels change, in conjunction with GDP growth statistics, we can learn how each part of the ratio is changing. If our money supply is shrinking, then we have deflation. If we have an expanding economy and no change in money, we again have deflation. If we have too much money, and our economy isn't growing fast enough, we get again, inflation. If we similarly have a shrinking economy and stable money, then again we have inflation. \n\n > **Distribution Methods**\n\nWell there are several ways the government could finance a guaranteed income. \n\n ***First*** of all, the government could simply pay for the guaranteed income with standard debt. The government sells some bonds and then uses future tax money and future loans to pay for current guaranteed income. \n\n***Second*** the government could institute a taxation and redistribution policy. This sort of policy would take individuals who make a lot of money and then tax them extra. Then with the extra tax revenue, the government could hand it to people who make very little and guarantee a minimum income.\n\n***Third***, the gov't could just 'print' (create) money and finance the entire program through non-standard money creation methods. This is not going to happen as this is almost exclusively used for economic crises.\n\n > ***Implcations***\n\nThere are generally two considerations for economics, the short term and the long term. The short run is when firms can only control production variables. The definition for the long term is when fixed costs are also considered variables. \n\n* **First Method** through **simple government debt**. \n\nThe considerations here are government debt levels, amount of money that is increased, and output (GDP) increase. Then we can consider the ratios to find out about inflation. \n\nGovernment debt levels increase but this should be financed by future government incomes and thus shouldn't be a problem (provided this isn't a crippling amount of debt). Now in the short run an increase in the money will actually stimulate the economy, create jobs because people want to buy stuff with their extra money. Firms will respond by increasing production. This means that there will be more money relative to goods in the short run (inflationary). But in the long run the ratio should bounce back to normal because production should equal the amount of demand (from the extra money). This means that there has been no net change in the price levels that is to say the purchasing power of the dollars haven't changed. The individuals with a guaranteed income are able to purchase more goods now since they have strictly more money and prices haven't changed.\n\n* **Second Method** through **redistribution**.\n\nnotabene: This is one of my favorite models because of its implications!\n\nOk lets begin. The considerations for this model are again threefold: Financing implications, Money supply implications and Output implications.\n\nFirst, the government's redistribution policy will have a very strong impact because we can say that the more money you make the more we take!. This can have dramatic effects because not only are we taking your money (so you have less to spend) but we are also de-incentivising you to make money! Think about it. As you make more money we take more of it. There will be some point were you would actually want to have more free time than to have money taken away. This means that redistribution policy will actually start to reduce output.\n\nNow does the amount of money given to the low wage earners actually offset the amount of output lost? No. Generally speaking higher wage earners earn more money because they produce more. The loss in output from the high productivity individuals is much greater than the extra output generated from a demand increase. They are different orders of magnitude. While there is a significant change in demand profiles of individuals because the money changes hand, there is no change in price levels due to the total production not changing and the money supply not changing. The redistribution results in a loss of maximum potential output but has the benefit of increasing welfare. Social welfare is a measure of how much total 'happiness' people can attain. Going from 0 dollars a day to 100 dollars a day will make you a lot happier than going from 10,000 dollars a day to 10,100 dollars a day. In the same way, we can take that 100 dollars from the high income individual and give it to the low income individual and dramatically increase overall welfare. This comes at the cost of maximum output for the entire economy but has the benefit of higher social welfare. \n\n* **Third method** through **Money Creation**\n\nI'm not going to go into these potential effects because they are even more complicated and unlikelier still! I'll provide some more reading at the end if you're interested into how money creation works. Try to use the information to figure out why it's unlikely the fed would choose to employ this option to finance government operations such as this. \n\n\n > ***Ending remarks***\n\nI hope you found this helpful! I enjoyed writing it and if you have any questions let me know. I'll do my best to provide concise and understandable explanations.\n\n > **Some sources**\n\n[New Keynsian Economics and Policy implcations](_URL_0_)\n\n[Money Creation](_URL_3_)\n\n[Welfare Economics](_URL_1_)\n\n[Quantitative Easing](_URL_2_)"
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5odami | Why did the Nazis attempt to remove any evidence of the camps existing? | Were the Nazis aware of the atrocities they were committing and were attempting to avoid being charged for war crimes?
| AskHistorians | https://www.reddit.com/r/AskHistorians/comments/5odami/why_did_the_nazis_attempt_to_remove_any_evidence/ | {
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"The destruction of the extermination camps, the cremation of bodies, and the excavation and cremation of shooting victims over the course of 1942-43/44 was constellation of different factors that aligned that pushed the Germans towards this aspect of the Holocaust. \n\nOne of the rationales behind the implementation of cremation at the Reinhard camps was practical. The large stacks of buried bodies was both a health hazard and impeded the ongoing operation of mass murder. As the bodies decayed, they created both noxious odors, attracted vermin, and polluted the water. This posed an ongoing health risk to the guards and German occupiers. The stench of death also made it hard to conceal the nature of these camps, which made the process of murdering new arrivals to the camps more labor intensive. Leon Feldhendler, a witness of the killings at Sobibor recounted:\n\n > In the first period, there was no crematorium. After gassing, the people were laid into the graves. Then, out of the soil, blood and a bad odor of gas began to surface; terrible smells spread over the whole camp, penetrating everything. The water in Sobibor became rancid. \n\nThe problems of Sobibor were similar in many of the other death camps as the summer of 1942 was quite hot and the corpses swelled in the burial pits, spreading disease and creating a noxious environment. These early cremations used both coke fuel and wood for fuel, but were inefficient. \n\nThe solution to the SS's problem came from a number of sources. Himmler had tasked SS *Standartenführer* Paul Blobel in early 1942 to eliminate all traces of mass execution in the Soviet Union. The operation, codenamed *Sonderaktion* 1005, sought to find the ideal and practical technical solutions to the problem of mass disposals. Blobel's team experimented with various methods at Chelmno and eventually found the ideal method was to stack alternating layers of bodies and fuel connected by railway ties. One particularly gruesome discovery of *Sonderaktion* 1005 was that human bodies acted as their own fuel, provided they were efficiently stacked. Yechiel Reichman, a Jewish inmate at Treblinka testified postwar:\n\n > The SS “expert” on bodyburning ordered us to put women, particularly fat women, on the first layer on the grill, face down. The second layer could consist of whatever was brought—men, women, or children— and so on, layer on top of layer. . . . Then the “expert” ordered us to lay dry branches under the grill and to light them. Within a few minutes the fire would take so it was difficult to approach the crematorium from as far as 50 meters away. . . . The work was extremely difficult. The stench was awful. Liquid excretions from the corpses squirted all over the prisoner-workers. The SS man operating the excavator often dumped the corpses directly onto the prisoners working nearby, wounding them seriously. \n\nFeldhendler similarly testified that the open-air cremations came from the problems of mass burial, which \n\n > forced the Germans to build a crematorium. It was a large pit with a roaster above it. The bodies were thrown on the roaster. The fire was ignited from beneath, and petrol was poured on the corpses. The bones were crushed into ashes with hammers. \n\nThis lesson that the disposal process was more efficient with more bodies became very important for camps with more permanent crematoria. \n\nBoth Dachau and Buchenwald had already installed their own crematoria in 1939. Although not death camps, these unhygienic conditions and general brutality created a large number of deaths among the inmates. The SS had previously farmed out these corpses to local crematoria, but the scale overwhelmed these local businesses and the SS realized that these corpses posed a public relations problem. The SS subcontracted out to two private contractors, Heinrich Kori GmbH and Topf & Sons, to create efficient crematoria suitable for mass burnings. Primarily utilizing coke for fuel, these crematoria used a variety of existing and novel technologies to recirculate heat. As Blobel and his team discovered, human bodies could act as their own fuel and their experience disseminated back through the SS's camp administrators. For example, Auschwitz's crematoria teams would mix fat and emaciated corpses together to create an even heat. The Germans constructed these permanent crematoria at the larger KL work camps and at Auschwitz-Birkenau, which began as a mass-labor camp but transitioned into a hybrid work-extermination camp as the Operation Reinhard camps wound down their operations. Kori and Topf also developed portable oil-fired ovens that could be sent to the areas needing quick disposal.\n\nBut permanent facilities also came with a liability in that they were direct evidence of violations of human rights. The Allies had formed the United Nations War Crimes Commission (UNWCC) in October 1942 which had begun to collect evidence of various war crimes and define and delimit the nature of Axis war crimes. The UNWCC kickstarted a process of examining existing treaties of international law and established that German legislation that allowed for such crimes was legally invalid because they violated international norms. The London International Assembly of the UNWCC in mid-1942 claimed that \"covering their crimes under a cloak of apparent legality should not help the Nazis to escape justice or that mere terminology or technicalities should not obscure the main issue.\" The London International Assembly recommended that not only was the Axis powers' war-making itself a crime, but other actions of the Axis should be matters of international justice. he idea of a postwar international tribunal became an official policy of the Allied powers with the [Moscow Declaration](_URL_0_) of October 1943. The Declaration's Statement on Atrocities claimed that the evidence of German war crimes was overwhelming and \n\n > those German officers and men and members of the Nazi party who have been responsible for or have taken a consenting part in the above atrocities, massacres and executions will be sent back to the countries in which their abominable deeds were done in order that they may be judged and punished according to the laws of these liberated countries and of free governments which will be erected therein.\n\nBut the Moscow Declaration went a step further than just promising punishment for existing war crimes and noted that \"the above declaration is without prejudice to the case of German criminals whose offenses have no particular geographical localization and who will be punished by joint decision of the government of the Allies.\" In short, the Moscow Declaration claimed that some German crimes were so vast and unprecedented they necessitated an international court system to be prosecuted.\n\nBut the Germans did not need the Moscow Declaration to understand that evidence of crimes was a liability. The Germans themselves had exploited the Katyn Massacre in its propaganda when it uncovered evidence of the Soviet shootings of Poles in the wake of Barbarossa. The Third Reich had publicized the Katyn massacres as an example of Communist barbarity and thus became acutely aware that the bodies still remain after their murder. Erasing the bodies erases the evidence of the crime. The lack of physical evidence would thus protect the SS, and by extension, Germany, from being held morally responsible for genocide. Himmler likely conceived of cremation as a means to dispose of masses of corpses on a tour of the front in the summer of 1942, and his desire to conceal the crime dovetailed with the hygienic and practical reasons pushing cremation in the Reinhard camps. By the time it was in operation, *Sonderaktion* 1005's main goal became to eliminate those areas that might be overrun by the advancing Red Army in Belarus and the Ukraine. Around the summer of 1943, the Reinhard camps began to run out of Eastern European Jews to murder, the SS authorities likewise excavated bodies from much earlier mass killings, dismantled equipment, and planted trees over the sites. But by this time But the growing sophistication of the extermination equipment made it harder to conceal and dismantle. Majdanek, which was a subsidiary camp for the main Reinhard camps, continued killing operations of leftover Jews in the General Government and Baltics, was captured nearly intact by Soviet troops in July 1944. The Soviet publicizing Majdanek's gas chambers and crematoria only reinforced the desire to conceal the remaining killing sites like Auschwitz II. \n\nBut beyond these practical and exculpatory reasons, the Germans themselves were divided over what should be done with the corpses of their victims. Odilo Globocnik argued to his superiors and colleagues that cremation implied guilt and that the Reich should instead construct vast ossuaries for Jews emblazoned with bronze tablets congratulating his generation for having the courage to see this difficult task through. Despite the fact that some of his superiors agreed with Globocnik's sentiments, including Hitler himself in one account, the Reich's leadership elected to destroy the majority of the Holocaust's corpses. But there still was an uneasy tension between the desire to cover-up the murders and the fact that the cover-up implied guilt. Himmler's infamous Poznan speech in 1943 encapsulated this tension when he noted:\n\n > One can consider at a much later time whether the German people should be told more about this. I think it is better that we – we as a whole – have carried this for our people, have carried the responsibility (the responsibility for a deed, not just for an idea); and then we will carry this secret to our graves.\n\nHimmler reaffirms that his SS men will follow orders and may have to carry knowledge of their actions to their graves, but also notes that *someday* Germans, and by extension the rest of the world, will know what they have done. \n"
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1cfbyr | How was sliced bread first received by the general public? Was it really considered one of the "greatest inventions?" | I'm of course asking about packaged pre-sliced bread. Was it immediately accepted as a great invention (per the phrase "the greatest thing since sliced bread"), or were people skeptical about it at first? | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/1cfbyr/how_was_sliced_bread_first_received_by_the/ | {
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"Automatic sliced bread was introduced to Chillicothe, Missouri in 1928 via a machine by Otto Rohwedder in Frank Bench's Chillicothe Bakery. The power driven multi blade slicer dated back to 1917, but had no takers until Bench. Sliced Klean-Maid Bread took off like a rocket and sales soared 2000% within weeks. By 1928, sliced bread was a national US sensation, and by 1929 sliced bread was available in most towns of more than 25,000. By 1936, 90% of commercial bread was sold sliced.\n\n(from Aaron Bobrow-Strain's book *White Bread: A Social History of the Store-Bought Loaf* )",
"Bread slicers were not introduced to some communist countries until post communism. I can speak from first hand experience that from 1991 to 1993 people were raving about sliced bread in those countries. In some stores you still have an option for sliced and non-sliced to this day in Eastern Europe, with an extra charge for slicing. \n\nI know this is somewhat anecdotal and just on the cusp of the cutoff year, but can we not accept oral histories if they involve the topic and are before 1993?"
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5ik8t2 | why are car model years not displayed on the car itself? | So I've always wondered why the make, model, and trim package of a car is displayed on the back of it, but nowhere to be found is the model year. I feel like for a lot of people (like myself) it's hard to distinguish the specific year of a car just by looking at it. I know you can determine this from the VIN, but that doesn't give you the information with a quick glance, especially if you don't want to look creepy trying to get a look at someone else's VIN. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/5ik8t2/eli5_why_are_car_model_years_not_displayed_on_the/ | {
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"You can look at the owner's manual in the glovebox. \n\nPutting dates on things is essentially an expiration date. People don't want you to know their nice looking car is 8 years old.",
"Because people don't want to advertise how old their car is. It would therefore be detrimental to sales. \n\nI can tell you that I've seen examples (in other countries) where the model year was incorporated as part of the license plate. People absolutely *hated* it, and complained vehemently until that law was repealed. \n\n",
"I realize this doesn't really answer your question, but at least in the US, the model year is on the emissions sticker under the hood. If you think looking at people's VINs is creepy though, opening the hood to check their emissions sticker is probably worse."
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6u5zdy | why are things that are hot to the touch, not so hot to the mouth i.e. coffee? | I've always wondered why I can drink a really hot cup of coffee and the cup is really hot to the touch, to the point where I have to put it down if I'm not holding by the handle, but when I sip it, it doesn't burn my mouth. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/6u5zdy/eli5_why_are_things_that_are_hot_to_the_touch_not/ | {
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"Because you're sipping that coffee very very lightly. You can easily splash a few drops of the same coffee on your hand and not feel a thing. If you took coffee that was 190 degrees F and had to decide to take a large sip and swallow it or spill the same amount at the same temperature on your hand, you would most definitely *not* choose the former. You'd fuck yourself up bad if you swallowed coffee that hot\n\nedit: you would most definitely *not* choose the former",
"Two reasons mostly. The first is that your mouth is actually built to handle somewhat warmer temperatures than your skin. So something that is just a little too hot to stick a finger into is probably okay to drink.\n\nThe second is that you usually aren't taking big gulps of really hot coffee - you're taking sips. And when you sip, you're mixing the fluid with air and spattering it across your mouth - this spreads out the heat and minimizes the amount of coffee that's actually in contact with your mouth. If you took a straw and swept a few drops of coffee across the back of your hand, it'd burn much less than that same amount all in one spot - that's what's happening inside of your mouth.",
"Is it possible that it also has something to do with your mouth being moist but your hands being dry? So basically the liquid covering the inside of your mouth cools down the hot tea/coffee before your cells can actually sense the change in temperature. Sorry for the lack of scientific terms, I could explain better in Hungarian...",
"Also your mouth is use to internal temperatures of 98.6degrees Fahrenheit but your skin is use to air temperature which is often closer to 75 degrees Fahrenheit. So if the coffee is 100 degrees then it's only a little warmer than what the mouth is use to but a lot warmer than what the hands are use to. "
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39458f | how do particles 'know' when they've been observed? | And what counts towards 'observing' them? Bacteria? Animal life? What? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/39458f/eli5_how_do_particles_know_when_theyve_been/ | {
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"The whole \"particles act differently when they are observed\" is misleading. A more accurate description is \"particles act differently when they are measured.\" This is because every method we have (or can imagine) of observing them alters some other characteristic than the one we are measuring.\n\nTL;DR: particles do not 'know' they are observed, we just screw with them every time we observe them.",
"To \"observe\" something, you shine a light on it, which means reflect a photon off of it. But when a photon reflects off of something, like a particle, that particle's spread out \"wave\" collapses.\n\nReally the idea is that to observe something, it has to interact with something, because we don't \"see\" an atom, we see light bouncing off of it."
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4s0tzc | Looking for some recommendations for these specific topics... | I am currently reading *Training for Policy Makers* (Dror, 2006), in which the author accentuates the importance of history for future leaders:
> [...] one or two books providing a vista of long-term history, a text or two on the dynamics of history, and another book or two in philosophy of history and historiography. More realistic when maximum reading requirements are limited is demonstrating thinking-in-history and exercising it by application to select grand-policy spaces.
The trouble is that I am not very familiar with these historical disciplines and the author is pretty vague when it comes to actual recommendations. I was wondering what were some good history books for "long-term history", "dynamics of history", "philosophy of history", and "historiography".
Also, I am interested in reading *Orientalism* by Said, and I was wondering in which category did this book fall.
I apologise if this is not the right subreddit in which I should post this, so feel free to redirect me somewhere else if needed be. | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/4s0tzc/looking_for_some_recommendations_for_these/ | {
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"Can you clarify what type of policymaking you're wanting to get into? While I can give you some suggestions for, say, foreign policy, I won't be of much help if you're interested in, for example, urban redevelopment.\n\nI wouldn't suggest you read Said's *Orientalism*. While it's an important work, there's no need to put yourself through the torture of reading it. Instead, read the Wikipedia page on Said and his thoughts on Orientalism in addition to (if available to you) Andrew Rotter's essay, \"Saidism without Said: Orientalism and US Diplomatic History\". Rotter provides a very good overview and criticism of Said's conception of Orientalism.\n\nEdit: Also, Edward Said would fall both into the \"historiography\" and \"philosophy of history\" fields."
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5iji0n | How do those little winter birds, like chickadees, not freeze to death, and, if they are just little well-insulated furnaces, where does all their energy come from, just seeds? | askscience | https://www.reddit.com/r/askscience/comments/5iji0n/how_do_those_little_winter_birds_like_chickadees/ | {
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"1. They insulate themselves from air by floofing their feathers (stagnant air between their feathers is an excellent insulator)\n2. They insulate themselves from ground by using a countercurrent heat exchange in their legs, aka a [rete mirabilis](_URL_0_) and by keeping their feet dry\n",
"Actually, if chickadees don't have a ready winter food supply (i.e. bird feeder) only 37% make it through the winter, while 69% make it if they do have access to a ready food supply according to this study: _URL_0_",
"Along with insulation and countercurrent exchange, another physiological feature to point out is that small birds, like chickadees, engage in regulated hypothermia. During night time and bouts of extreme cold, they can lower their body temperature about 15 degrees celsius below normal, which saves tremendous amounts of metabolic energy. This is called daily torpor, and isn't to be confused with hibernation. ",
"Already great answers so far, but I would like to add shivering. By shivering, small birds are able to keep creating a little bit of body heat. That's also why we shiver*, though it's not as effective. \n\n\n*to keep ourselves warm, not to keep tiny songbirds warm.",
"When I went to the Thompson Morrison (sp?) visitor center in Fairbanks, AK, I remember one of their displays saying that their hippocampus grows about 30% in the winter so that they can remember where they hid their seeds, then it shrinks in the spring/summer back to normal. Remembering where more seeds were hidden might help keep them warm? ",
"They fluff their feathers up to trap a layer of air between their body and the cold air. This works the same way as a dry-suit for people to go into cold water.\n\nThey keep their feet from freezing with a special net-shaped network of arteries that's designed to allow the blood to cool before it reaches their feet. This way, they keep the feet just warm enough to not fall off, but they don't lose as much energy.\n\nThey eat almost entirely seeds through the winter, and a lot of then actually don't make it because they run out of food. That being said, seeds are fairly rich in calories so if they have a good supply they are pretty likely to survive winter.",
"Currently there is a cold snap here for the last couple of weeks dipping to -11C at night. And I have two nectar feeders that I bring out every morning just before daybreak for about half a dozen Anna's Hummingbirds. A percentage of the population will stay behind and get a head start on nesting over the winter instead of heading to the tropics. I find it endlessly fascinating that a creature smaller than my thumb can manage such temperature swings. ",
"I didn't read all 121 comments. But it's not just the SEEDS - it's the fat in them. Lots of people put out suet feeders - those blocks of fat with seeds and berries and such in them. Where there's suet feeders, there's bound to be tons of birds getting every bit of fat they can get to survive the temperature. This paired with an extremely fast metabolism, insulatory down feathers, and constant preening to make sure the feathers are DRY. ",
"Question: Some common birds that stay through winter around here are black. Is that so they get warmth from the sun? Does that even matter? Do they sit on top of trees and roofs etc. also for that reason or is that just for defense?"
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7rjdhu | si definition of a second | [deleted] | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/7rjdhu/eli5si_definition_of_a_second/ | {
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"Basically, they took what they knew as a second, and because everyone has slightly different biological clocks, they needed a standard definition.\n\nThere were 3 ways to compute this.\n\n1. 1/60th of a minute, which was 1/60 of an hour, which is 1/24th of a day. (The regular definition, used for old-timey clocks, but can vary based on changes to the day). \n2. The length of time light needs to travel a certain distance in a vacuum. \n3. Or a large number of steady changes that can easily be observed on Earth, like the number of cycles of a cesium atom's radiation.\n\nIn reality, they equal the same thing, 1/60 of a minute It's just about agreeing *exactly* how long that is.",
" > The second is the duration of 9192631770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom.\n\nAlright, start in reverse.\n\nCaesium-133 atom. [Caesium](_URL_0_) is an element. It's liquid at room temperature, and the most reactive of all the metals. If an atom has 55 protons it is caesium. But it can vary in the number of neutrons it has. These options are called \"Isotopes\", Caesium-133 is the only isotope of Caesium that is stable, it doesn't break down over time. It's not particularly hard to get your hands on a bunch of Caesium-133.\n\n > the two hyperfine levels of the ground state\n\nEssentially, if atoms get energy they change their hyperfine levels. This refers to a situation where it's energy changed in a specific way. You can't halfway change levels, it's either at one level, or at another. \n\n > the radiation corresponding to the transition between\n\nWhen the state changes, energy is released, radiation. We're talking about the radiation that is released when you change the levels. It's always a specific radiation because the state change is always the same.\n\n > 9192631770 periods of the radiation\n\nRadiation is a wave, a period is the time between the tops of two of the waves. So we're finding the period of our wave of radiation, but taking 9192631770 of those. \n\n > The second is the duration of \n\nHow long those 9192631770 wavelengths take, that's what a second is."
]
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1mkwfo | Costa Concordia Salvage: Was there any new technology developed or had never been tested that was required for this operation? | [Here's a BBC news link about the operation.](_URL_0_) | askscience | http://www.reddit.com/r/askscience/comments/1mkwfo/costa_concordia_salvage_was_there_any_new/ | {
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"The main techniques used in the Costa Concordia's salvage were hot-tapping to safely remove fuel from within the ship, a process which has existed for at least over a decade and involves the pumping water into the ship to maintain equal pressure while the fuel is being removed. The main method of righting the ship so that is can be taken away to be scrapped was parbuckling which has been in use for over 70 years and involves applying force to rotate the ship upright. Whilst the Concordia is the largest ship salvaged via parbuckling it as far as I can tell did not require any new technology."
]
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"http://www.bbc.co.uk/news/world-europe-24121480"
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rfa7v | what is it about how birds fly that humans haven't been able to replicate for human flight? | I'm talking about human-powered or human-assisted wings. Flying machines are still very expensive, too large, and not very portable. Gliders have some of the same problems. What does it take to get a human being airborne from a standing position like a bird? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/rfa7v/eli5_what_is_it_about_how_birds_fly_that_humans/ | {
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"Hollow bones, and a whole lot of other things that make flying animals lightweight and aerodynamic. ",
"Light, hollow bones. Humans are simply too damn heavy.",
"birds have a huge wing to body ratio, if we were to have wings proportionally as large as a birds for our size/weight they'd be like the size of a bus.\n\nnote: this isn't based off any precise calculations. ",
"Human-powered wings just aren't practical due to lift and weight considerations. \n\nAll living things fall victim to something called the square-cube law. This says, essentially, that volume grows faster than area. Say I have a cube one unit on each side. Each face of the cube (as well as any non-tilted cross-section) has an area of one square unit, and the cube as a whole has a volume of one cubic unit. But if I take the cube and expand it until each of its sides is two units long, its faces now have an area of four square units—and the whole cube has a volume of *eight* cubic units. How is this important to biology? Well, imagine a living thing that walks around on legs. A dog will do. Now, the dog's weight is determined by its volume. But the strength of the dog's legs—how much weight they can support—is determined by the area of their cross-section (that is, if we cut off the bottom of the dog's leg, how big a circle the stump would make). If we took the dog and scaled it up so that it was twice as long, nose-to-tail, as it was before, it would have eight times the volume, and be eight times as heavy. But since the strength of its legs goes up with area, they would only be able to support four times the weight. The dog is now twice as heavy as its legs are meant to support! It wouldn't be able to do much, even if we hadn't cut off that leg. Large animals have to be built differently, and have different proportions, than smaller animals in order to function. This is why animals like elephants and sauropod dinosaurs (the really big kind) have thick, strong legs compared to smaller animals like cats or dogs or people.\n\nTo fly, birds have to create enough *lift* to overcome gravity and allow them to rise. Lift depends on two things: how fast air is moving around the wing, and how much area the wing has. The force of gravity depends on how heavy the bird is (if you're remembering that heavy objects don't fall any faster than light ones, you're right, but the *amount* of force is related to mass, in accordance with Newton's law of gravitation). As we just found out, the bird's weight—and thus the force exerted by gravity—goes up with the cube of its size, while the area of its wing—and thus the lift it can generate—goes up only with the square. This spells trouble for really large birds. They must have wings that are much larger in comparison to their bodies than small birds, and even then there are biological limits on how large a wing a bird's body can support. Yes, there are birds whose bodies are [nearly the size of](_URL_1_) or [even larger than](_URL_0_) a man's, but they depend heavily on assistance from airspeed (the other factor in generating lift I mentioned above) and currents. To use those two examples, the albatross (and other birds of the open ocean) depend on the high winds, or sea shear, that occur over the ocean; *Argentavis*, and other birds like it, soar on warm thermals that help push them upwards.\n\nFinally, the adaptations for light weight and aerodynamics other commenters have mentioned also come into play. Humans aren't shaped for flight. Birds' entire physiologies, from beaks to bones to feathers to digestion, excretion, and reproduction are designed to save weight in ways that humans' simply aren't; a bird the size of a human is not only more aerodynamic but substantially lighter. (Proportionally, a human would require [preposterously huge](_URL_2_) wings to bear their own weight—far larger than would be safe to carry around, even if artificial production freed them from the limits of growth.) What's more, humans don't have the respiratory, muscular, or skeletal adaptations to flap and maneuver wings the way birds do—we can't acquire oxygen anywhere near as efficiently, we don't have the huge, cleverly hinged breast muscles they use in their power flap or the keeled breastbone to attach them to, and the joints in our arms and shoulders don't move the right ways. *If* a a human with a huge glider were assisted by extremely high, wind-tunnel airspeeds, or air blasts from below mimicking thermals, they might be able to gain some little height, but they would never be able to flap their wings and rise—and agile flight, or flight from a standing start? Not happening! (At least, not until we [escape gravity](_URL_3_).)"
]
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"http://en.wikipedia.org/wiki/Argentavis",
"http://en.wikipedia.org/wiki/Wandering_Albatross",
"http://www.politedissent.com/archives/987",
"http://www.baenebooks.com/chapters/0743498747/0743498747___2.htm"
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5trz7k | do car headlights move faster than the speed of light? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/5trz7k/eli5_do_car_headlights_move_faster_than_the_speed/ | {
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"No, the headlights will always travel at speed of light because speed of light is constant. So, in order to compensate, the moving object will experience time dilation.",
"Nope, photons travel at the speed of light for whatever medium they're traveling through (barring some very specific situations). Even if your car was somehow doing 99.999% of the speed of light the photons would still be moving at *c*. "
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s1hri | Why do animals (including humans) lick their wounds? | askscience | http://www.reddit.com/r/askscience/comments/s1hri/why_do_animals_including_humans_lick_their_wounds/ | {
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"Saliva has natural antiseptic in it, which helps keep the wound uninfected. Also it can remove bits (like gravel from a graze) which could harbour infection.",
"Saliva contains several growth factors that promote healing (TGF, EGF). Animals with their salivary glands removed heal slower. Heres one article, but there are plenty of others. _URL_0_",
"I found this Wikipedia entry informative: _URL_0_ While saliva does kill some bacteria, it also spreads others. In veterinary medicine wound licking is discouraged because it does more harm than good. ",
"Suppose you cut your finger, wouldn't licking/sucking on a cut be bad because you're sucking up clotting factors?",
"As people have said, there are some benefits of the saliva to the wound, but there are other benefits, too. The Gate Control theory of pain regulation is pretty fascinating and it states, in a nutshell, that pain sensory from nociceptors and other touch sensations from mechanoreceptors both synapse with the same interneuron before reaching the brain. Thus, the more sensory input that body part receives, the more the interneuron will have to pick and choose between the sensations and thus the pain signals will be projected less into the brain. This is why you rub parts of your body when they hurt or hop around holding your foor when you stub your toe."
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3s2i3o | why do people abandon houses? | For example, I grew up in a very rural area in western Wisconsin and the ridges and valleys are peppered with abandoned homes, which have clearly been vacant for decades. Any idea why? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/3s2i3o/eli5_why_do_people_abandon_houses/ | {
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"There's a variety of things that happen. Sometimes a person moves away, or the house is inherited by a faraway relative. If these people can't or don't want to be landlords, and are unable to sell the house, they're stuck with the property taxes. They might just forget about the property, instead...if the county eventually tries to sell it as a tax seizure, nobody will want to buy the by-then derelict house.\n\nOther times, housing prices drop, and people have a mortgage that's worth more than their home. They might decide to run away from the mortgage and forget about the house, since that way they might be able to escape the extra debt. This is a more modern phenomenon.",
"A lot of reasons. But typically the reason is it costs too maintain the property, with hope of being able to sell it to someone else. \nIn rural areas, jobs may disappear, and people are forced to move to a different area. \n\nPeople typically don't abandon property they think has value."
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66xif0 | why does machine-made ice cubes have holes in them? | When I make ice cubes at home (in a tray) the cubes are perfectly square, but at restaurants the ice cubes have a hollow part on one of the sides... why? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/66xif0/eli5_why_does_machinemade_ice_cubes_have_holes_in/ | {
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"Because that machine makes ice by taking a metal rod, chilling it to below freezing, and then spraying water onto it, where the water freezes. When the ice is thick enough, the machine briefly heats the rod- the inner layer of ice melts, and the rest of the cube slides off and falls into the hopper.",
"When you make them at home, you fill compartments in a tray with water and freeze the entire thing, so each compartment becomes an ice cube. \n\nIce makers work slightly differently. They have an array of fingers (or prongs or spikes, whatever) which are dipped into a container of water. These fingers are chilled, causing ice to form around them and build up into the shape you know. \n\nThe fingers are [lifted out of the water, each covered in ice](_URL_0_). They are warmed very slightly, allowing the ice to fall off, leaving the hole in the middle. \n\nFreezing around the fingers is faster than waiting for all the water to freeze. "
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"http://cdn.newair.com/kb/wp-content/uploads/2013/07/ice-1-300x200.jpg"
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32kt5m | what is the difference, if any, between extra strength tylenol over the counter vs. prescription? | I have a whole bottle at home, why would I spend the money on the prescription version? Thanks! | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/32kt5m/eli5_what_is_the_difference_if_any_between_extra/ | {
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"Prescription gives you a higher dosage, so for example instead of two pills, you only have to take one. And, at least in the U.S., it's likely the prescription Tylenol will be covered by your health insurance. My mom is a nurse in a clinic, and a lot of people on Medical Assistance ask for prescription ibuprofen because MA will pay for it. ",
"Honestly, there's not a whole lot of reason to. Typically over the counter Tylenol will be a 200 mg dose, while prescription may be 1000 mg. You could take five over the counter pills and get *almost* the same result (with some minor variation in uptake time).\n\nThat said, always talk to your doctor and ask for clarification, they're much more reliable than some schmuck on the Internet. ",
"Not a pharmacist, but here in the US...\n\nOTC Tylenol is 200-500mg of acetaminophen.\n\nScrip Tylenol 3 is 300mg acetaminophen + 30mg codeine.\n\nScrip Tylenol 4 is 300mg acetaminophen + 60mg codeine.\n\n",
"Dosage\n\nBtw, you should generally avoid acetaminophen if it all possible. \n\nIt is a much more dangerous drug than most people realize.",
"Another reason not mentioned here is certain insurance programs will subsidize the cost of a prescription, but not OTC medications. I worked at an ED where the MDs would write a prescription for something like acetaminophen or naproxen because the patient was able to save money this way, over paying the full price OTC. ",
"In the US there is no Rx strength plain acetaminophen. It is all over the counter - 325 or 500 mg. There are many combinations with other meds with acetaminophen that require a Rx. Most are narcotics."
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6zo38q | why does agitating (rotating/stirring) concrete prevent it from setting? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/6zo38q/eli5_why_does_agitating_rotatingstirring_concrete/ | {
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"The process of concrete curing is essentially the binding of molecules/polymers chaining together. The higher the concentration of bound molecules the harder the concrete gets. Stirring a polymer or a solution that is in the process of curing breaks a percentage of the bonds that are slowly forming. Therefore the more you stir or mix the solution the more bonds you are breaking which in turn, sets back the curing process. Eventually the bonds will form but stirring it decreases the formation rate of the bonds between molecules. ",
"Agitating concrete will only delay the setting process by preventing some of the bonds in the material from forming and breaking some of formed ones but it will still begin to set eventually. \nThere are a lot of factors that go into to setting concrete.\n\nIMO, the most important place to start is knowing your aggregate. Our concrete stone and sand are tested in our lab every week to determine moisture content, gradation, density, wash pass etc.. Since most aggregate is stored outside it is likely the you will never know the exact moisture content of that stockpile at any given time. So most producers assume that the moisture content is the lowest tested value to make sure that there is not too much water in the mixture. After the product is in the truck it heads to the staging area where it is up to the driver to observe the mix and add water to the truck directly if needed. You can always add more water, its much trickier to lower moisture content than it is to raise it. \n\nNext is the type of plant you have, there are two main types of plants, Transit mix and drum mix. Transit mix is what you will see a lot, it is what fills the rotating drum type concrete trucks that constantly agitate the material. Drum mix when there is a larger version of that drum on the plant itself and the concrete is mixed before entering the truck which can be a dump truck. These two plants are used for different situations. It really depends on the job location and tonnes per day you wish to produce. A lot of portable plants are drum mix while stationary plants are generally transit mix and some can be both.\n\nFor transit mix like you are referring too the rotating drum on the truck is to ensure a proper mix of the concrete right up to the moment it is poured since it is not mixed in the plant and its keeps the gradation of the concrete consistent (No settling).\nGetting the right mix and setting time is as much an art as it is a science (Sort of).\n\nThere are other factors that may effect setting time such as contaminants. If recycled glass or ceramic is used in the mix for instance it must be free of all sugars as sugar is an inhibitor which will delay setting.\n\nKeeping these and other factors in mind (Job location, plant volume, what you're pouring, etc..) should all be considered when designing the mix to ensure that the concrete can be properly transported to the job site from the plant and it is still in a state where it can be properly poured. If you are pouring multiple trucks then you also want to make sure that there are a few trucks waiting on site so that the next truck can be poured before the previous load begins to set. This means that you also want to have an adequate staging area and process back at the plant so there is a continuous rotation of Filling, staging, transporting, and pouring trucks.\n"
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q5wi8 | What were the most important socio-political effects of the Little Ice Age? | Been doing some reading on the influence of climate on civilization, and I'd love to hear a historian's take. Thanks! :) | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/q5wi8/what_were_the_most_important_sociopolitical/ | {
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"You gotta be more specific. The Little Ice Age lasted from the Middle Ages to the Victorian Era and you'd expect that for such a long period of time, with specific dips in temperature, great changes have happened.\n\nThe demise of the Greenland colony was certainly the first one. There were tons of famines in Europe that were tied into a simply insane amount of wars that popped up during the time - the Thirty Years War was the big one, obviously, but really it was just the cap on hundreds of years of almost continuous warfare throughout Europe. This also coincided with the Reformation, so it's hard to say how much of it was famine-based and how much of it was just people being people and you know what. You might want to note that the migration of people was definitely related to climate change, but boy, this can go on forever.\n\nIn China, it heralded the invasion of the Manchus in the 1600s and the internal migrations that allowed for people like the Hakka to move out of the central plains and into the Guangzhou area. Actually, the overall movement southwards of the people led to the rise of trade in the south, but this was a slow process and also related to the overall violence of a lot of the internal issues in China.\n\n",
"IANAH, but I once read it had the non-trivial effect of causing beer to be the preferred alcoholic beverage of northern Europe since the colder temperatures discouraged northern wine production in favor of grains. ",
"I will throw some Medieval stuff into the ring...\n\nThe little Ice Age brutalized crop production during the 14th-15th centuries...which, incidentally was the same time that the Black Death was making its way across Europe (remember that, it becomes important). As a result of the cooling period which began in the early 14th century the warm summers that Europe was accustomed to were no longer reliable, and when it was fairly warm torrential rain fall usually caused most farmland to become unusable. As a result, the vast majority of the medieval population (laborers) was weakened, this is when the Black Death comes in. \n\nThe Black Death makes its way up from the south and coming in from the east and proceeds to whip Europe's ass. The already starving population suffered catastrophic levels of death from the plague (90% of a population could die in some places and there is evidence of towns that simply fell off the map). The nobles, unsurprisingly, made it out alright and still demanded that the local populations pay them with food for the protection they could no longer really offer as the warrior class had been hit hard by the plague as well. The laborers seemed to know this, and we see a sharp rise in rights and privileges granted to the laborers as they were now a dwindling population and could demand more for their work as there were fewer of them to do it.\nExamples include easier mobility between castes and lower taxes.\n\nIn summary. the Little Ice Age and the Black Death hit Europe hard during the same period, resulting in significant population drops, especially in the labor class. As a result of this drop there were fewer laborers/farmers to do work for the nobles and the laborers were able to gain freedoms, rights and privileges from their aristocratic lords, as the nobles needed those that were still alive on their side. "
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36zym4 | Did ancient Egyptians travel to the United States? | Just watched a show, seemed pretty questionable, that stated that there is a cave in the Grand Canyon with ancient Egyptian relics, because they had traveled there. Apparently, some guy made a boat out of papaya to test to see if it was possible, and I guess it was.
Is there any indication this actually happened? | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/36zym4/did_ancient_egyptians_travel_to_the_united_states/ | {
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"There have been no ancient Egyptian artifacts found *in situ* anywhere in the New World. [Thor Heyerdahls](_URL_0_) expedition from South America across the Pacific in 1947 merely showed that long distance sea travel in the distant past was possible, not that it actually occurred."
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8xo7ko | this may be a dumb question but how does a car/truck tire handle the weight from the vehicle and not pop? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/8xo7ko/eli5_this_may_be_a_dumb_question_but_how_does_a/ | {
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"They're simply really big. The larger the area you have touching the ground, the more weight you can have.\n\nLet's say you put three tons balancing on a needle. You're taking all those three tons, and concentrating them on one single spot, and that needle is gonna pierce right down through the asphalt. However, say you put three tons on a sled. The sled's large surface area helps to spread out the three tons, and you put it on the ground with no problem. Tires may not have as much area as a sled, but they still have quite a large contact area, enough to allow trucks and cars to drive effortlessly.\n\nThis is also why tanks have tracks, by the way. America's main battle tank, the M1A2 Abrams, weighs 70 tons; the tracks are absolutely massive to help spread out those 70 tons.",
"In addition to what /u/SkyEyeMCCIX said, they're also thicker and made out of far stronger material than your average balloon. \n\nEngineers design things based on [stress](_URL_0_). Whatever material you're working with has a *strength*, which is the max amount of stress it can withstand before breaking, bending, popping, snapping, or whatever. The stronger the force you apply to your part, the higher the stress. But if you make your part bigger/thicker/bulkier, you lower the stress. So if you're designing a tire for a certain pressure and it keeps popping, it means the stress is too high. So you either make the tire walls thicker (reduce the stress), or you use a stronger material that can handle that stress level, and then the tire won't pop."
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62755n | as an overweight male, why it's better for me to gain muscle via weights to lose weight than to do just cardio & reducing calorie intake | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/62755n/eli5_as_an_overweight_male_why_its_better_for_me/ | {
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"It isn't. You should do weights and cardio and reduce caloric intake. Better yet do some intermittent fasting, cut out all sugar, drop carbs to around 100-150 grams per day, and increase good fat intake. If you can restrict all consumption of anything but water to a 10 hour period every day you will be even more successful. \n\nIt's a synergistic effect. Larger muscles consume more energy which means less of your caloric intake gets stored as fat. ",
"because those muscles consume calories all the time, even when you sleep, so having more muscle mass is like having a furnace constantly burning away calories.",
"You should do them all.\n\nReducing caloric input is crucial to losing weight. However most people don't just want to lose weight but become more physically fit and healthy, which cardiovascular exercise helps with. This focuses on improving your ability to drive oxygen into your blood, carbon dioxide out of your blood, and circulate that blood to all of your body efficiently. Such exercise improves the supply side of your metabolism of calories.\n\nWhat building muscle does is increase the amount of tissue available to consume calories in volitional movement. It also is what most people think of when they imagine \"losing weight\" as if a muscled guy exists within every flabby guy. It isn't actually that way so building muscle is necessary, otherwise reduced caloric intake will turn a fat flabby guy into a thin flabby guy.\n\nThe order is this: Reduce caloric intake through adjustment to your diet. Cardio simply isn't going to burn enough energy to make up for poor eating habits so this change needs to happen first thing. Whatever change you make needs to be permanent so make it something you can cope with. No cutting out your favorite foods completely, just reduce what you eat now to a more reasonable total. Unless you have some dramatic nutrient deficiency you probably don't need to alter *what* you eat, just *how much of it* you consume.\n\nAlso at this stage you should work on cardio exercise. This will feel bad because your lungs and heart are lazy bastards and protest at being worked. However this is the stage where progress will make you start to feel much better and result in the most dramatic health benefits on a daily basis. Progress is made quickly though and weight loss benefits are marginal so after a couple weeks you will just be maintaining fitness levels, not gaining much.\n\nThe next step is to lift weights and build muscle because now you have the lungs and heart to support them. Don't start pounding protein shakes, you aren't some body builder who needs them. Normal protein intake for a western diet is plenty. High weight and low reps builds muscle while high reps and low weight refine the efficiency of that muscle. I suggest first trying to build muscle mass as this provides the best visual benefits and increases the baseline calories required to maintain, further increasing the impact of your reduced caloric intake. However building enough muscle to consume a candy bar through baseline metabolism is far, far more difficult than just not eating it.",
"tl;dr: Exercise is for health and fitness. Diet is for weight loss/gain. \n\nI think you're misguided. It is much, much harder to burn excess calories than to avoid them in the first place. If you want to lose weight, find out your [caloric needs](_URL_0_), then eat 500-1000 calories fewer than that. Also, be sure that you don't underestimate how many calories you're eating. In my experience, specific diets don't really matter; they're just different ways to \"trick\" you into eating less.\n\nAs far as exercise goes, some say that strength training is better for long-term weight loss. This is because muscle takes energy all day long to keep going, whereas cardio only burns energy during exercise. However, unless you're a professional bodybuilder, the effect is negligible. Even if you do burn calories during exercise, it isn't really worth taking into account.\n\nThat said, lifting weights and doing cardio a few times a week is still a good idea. If nothing else, it is easier to put on muscle if you're overweight because you have copious energy reserves. ",
"It isn't an either/or thing.\n\nStrength training will increase your muscle mass, which will increase your metabolism, causing you to burn more calories all the time. The other benefit is it makes it easier to move and be more active...some people get so out of shape they have to work to get fit enough just to exercise normally.\n\nBut strength training itself doesn't burn many calories, that's cardio does.\n\nLet's take a look at some completely made up numbers. If you weight 250 lbs., you are probably burning about 2500 calories a day just sitting still, which means if you eat that main, you at neither gaining or losing weight.\n\nIf you strength train, that might go up 5%, so now are burning 2625. If you do 30 minutes on the elliptical, that's about 500. And if you watch your diet, you could cut out another 500. So that is 1000 due to diet and exercise, vs. 125 from increases muscle mass."
]
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[],
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"https://www.google.com/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=caloric+need+calculator&*"
],
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||
9z42vk | What was the experience of the indigenous peoples of the Americas to lose so many of their members to colonialism, slavery, and diseases? | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/9z42vk/what_was_the_experience_of_the_indigenous_peoples/ | {
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"*part 1*\n\nThis is a huge area and topic, where experiences would vary accordingly - I'll focus mostly on central Mexico as per usual, although there are many parallels with other parts of Spanish America. Overall, the easy answer would be that of course, there was not only one experience of or response to conquest and diseases and slavery.\n\n There were many responses, ranging from lamenting the dead, to the need to record one's ancestors' possessions and histories in the face of tragic population loss. But despite the demographic catastrophes, indigenous cultures continued to adapt and survive until today - far from supposedly \"giving up\" or showing despondency, as many European colonial writers would have it.\n\n----------\n\nTraditionally, most history writing on the conquest campaigns and colonial period in the Americas has drawn on European sources. Often Spanish writers would describe the conquest as “zero hour” and a major event in human history. For conquistadors this made sense in order to glorify their own deeds; for members of this clergy this could underline their self-appointed mission of converting the native population to Christianity. Especially conquistadors (like Cortés in Mexico) helped also to create a narrative of supposed “native despondency”: this meant that native Americans were supposedly so overwhelmed by first the Spanish forces and then by colonisation that they would often respond passively or sort of give up. \n\nAt least for colonial Mexico but also many other regions, the last 30 or so years have led to a big inrease of great works drawing on all kinds of indigenous sources – written, glyphs, maps, quipu (textiles) among others. One consequence of this has been to challenge more traditional views of the conquest as those sketched above. Just to mention a few, Matthew Restall has countered what he calls this “myth of native despondency”. For him, native Americans actually responded very actively and intelligently to the Spanish intruders. In places including Mexico and Peru, indigenous groups or factions would form alliances with (and sometimes against) the Spaniards in order to improve their own situations. He counters claims of the natives' supposed fear of European weapons – native were actually very quick to take up and adapt weapons including swords and fireweapons from the start. \n\nMoving beyond the conquest period, we can see continuities with the pre-Hispanic period as well as adapting of European culture in all domains. In central Mexico, native intellectuals and communities were taught Latin alphabet in order to aid in their conversion. This was then used in a variety of major projects that have actually helped to pass on pre-hispanic history and traditions until today. Native languages and beliefs were changed, certainly, but have also continued to stay in use in various forms – e.g. with “imperial” languages like Quechua and Nahuatl made *more* important than before though the religious orders' efforts, while others languages were more marginalized. And with elements of native beliefs often surviving through the creation of a mixed “native Christianity” (all these are huge topics of research, so simplifying a bit here).\n\nImportantly, such a focus on continuities should not in any way downplay the major and catastrophic effects of colonialism, diseases etc. on native populations across the Americas (and elsewhere). In parts of New Spain/colonial Mexico alone, mortality rates from the many diseases that hit the indigenous populace until the early 17th c. could go up to 90%. These were then compounded early on by slavery; and when native slavery was abolished in the mid to later 16th century, native people continued to suffer harsh working conditions under the encomienda and then the repartimiento work systems. In addition, at the turn of the 17th century in different regions of Spanish America a reorganisation of communities took place. Through this, large numbers of people left their traditional lands, or where forced to seek work elsewhere. At the same time, the huge population loss meant that many nearly empty villages where “taken over” by Spaniards and other groups.\n\nAll these, and esp. the demographic catastrophe were noted and lamented by native authors. Of course, since most writings that have survived (at least again for central Mexico) come from members of the native elites, their focus could also include the loss of political and cultural influence after colonisation. But many writings and paintings by communities were also made, often collectively, that reflect upon the losses suffered – both in community members, and in properties and traditional lands. This is to say, that focusing on the existing continuities from pre-hispanic to colonial times should not mean to relativize the very real suffering and loss of people and traditions that conquest and colonisation meant. So that while the Spanish conquest is usually perceived as one among others, the direct, often devastating effects of colonial rule and reorganisation are very much chronicled, and in many cases proved more consequential than the conquest itself.\n\nGoing back to the initial Spanish claims of a “zero hour” – interesting studies like those of Stephanie Wood have argued that in central Mexico the Spanish conquest was not seen as a major event at all. Rather indigenous chroniclers would simply see it as one more in a long line of conquests in Mesoamerica. Wood (in “Transcending the Conquest”) discusses among others pictorial sources, where the Spanish are not portrayed as particularly special or menacing; they are just another group, albeit with a different skin color. For her. Such sources do not reflect a “radical difference” of the Spaniards and their practices from the indigenous POV. Rather Spanish modes of though and structures are integrated into Mesoamerican ones. This, again, goes counter to claims of Spaniards who of course had very different interests in portraying these events as major cataclysms of change.\n\n Some writers like annalist Domingo de Chimalpahin (writing in the early 17th c.) would even see the Spanish conquest of his ancestors, the Chalca, as a much less distruptive event than their earlier conquest through the Aztecs. After all, the Aztecs for a few decades removed the ruling dynasties from power, while under the Spanish these Chalca families could hold onto their rule for some time. This perspective again points to larger trends: At least until the mid- to late- 16th century, in many parts of central Mexico native elites held their posts of influence and possessions, although their influence would usually decrease afterwards. \n\nTo some this up, an increasing inclusion of native perspectives has then shifted the focus towards indigenous agency, and continuities with pre-hispanic structures and traditions. This helps to also overcome earlier studies that have focused on a supposed “incomparability” of the Americas or possible “acculturation” of native people. Lisa Sousa sums some of this up well (in “The Woman Who Turned Into a Jaguar”):\n\n > [b]y focusing on mechanisms of indigenous production and the work of native women [and more generally native people] ..., we decenter the traditional focus on the North Atlantic and Europe, [and] challenge historical narratives of western progress and the civilizing influences of colonialism.\n\n"
]
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[]
] |
||
2z6m70 | What is your personal recommendation for an audiobook on the history of the United States? | I'll be driving a bunch. I'd rather not pay more than $50. I looked at the book list in the sidebar but it seemed mostly geared toward specific subjects.
Bonus points if the author/reader is engaging and/or funny. My favourite popular history author so far has been the Swedish _URL_0_ - who is apparently no stranger to controversy, but writes in a very accessible and humourous way.
Thank you. | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/2z6m70/what_is_your_personal_recommendation_for_an/ | {
"a_id": [
"cpg7r2b"
],
"score": [
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"text": [
"Have you considered any of the Great Courses series of lectures on Audible?"
]
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"https://sv.wikipedia.org/wiki/Herman_Lindqvist"
] | [
[]
] |
|
1yix79 | Is there a way to measure the amount of matter\mass in the universe? Is it a finite amount? | askscience | http://www.reddit.com/r/askscience/comments/1yix79/is_there_a_way_to_measure_the_amount_of/ | {
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"text": [
"We can't measure anything outside of the observable universe per definition, so we don't know if it's finite. Our observable universe should have about [1.45×10^53 kg](_URL_0_) of ordinary mass (excluding dark matter).",
"Since the furthest objects visible from Earth appear to be receding from us to the extent that their light takes around 13 billion years to reach us, it would seem we cannot say what lies beyond them; any estimate of the matter will be based only on what we can see."
]
} | [] | [] | [
[
"http://en.wikipedia.org/wiki/Observable_universe#Estimates_based_on_steady-state_universe"
],
[]
] |
||
1i6yyy | When I close my eyes, am I flexing or relaxing my eyelid? | askscience | http://www.reddit.com/r/askscience/comments/1i6yyy/when_i_close_my_eyes_am_i_flexing_or_relaxing_my/ | {
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"text": [
"You are contracting the [orbicularis oculi muscles](_URL_0_) when you forcibly close your eyes.",
"You're not doing anything to the eyelid; what you are doing are flexing/relaxing muscles connected to it.\n\nNow the general rule for muscle antagonism applies here: so opening *and* closing eyes involve *both* relaxation of one muscle and contraction of another (similar to the relationship between your biceps and triceps).\n\nSpecifically, [this is the muscle](_URL_1_) that opens the eyes; its contraction pulls back the eyelid. It is opposed by [this muscle](_URL_0_); its contraction closes the eye.",
"Responses in this thread seem to be contradictory. I'm hijacking it to add a follow-up question, which probably satisfy OP's curiosity too if answered.\nTO doctors/nurses/paramedics: have you ever witnessed a complete flaccid paralysis of the face or at least the eyes area? What did the eyelids do?"
]
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"http://en.wikipedia.org/wiki/Orbicularis_oculi_muscle"
],
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"http://en.wikipedia.org/wiki/Orbicularis_oculi_muscle",
"http://en.wikipedia.org/wiki/Levator_palpebrae_superioris_muscle"
],
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||
9syky2 | Why do mitochondrial diseases affect different parts of the body? | Our mitochondria is the same all over our bodies , and as far as i know its genes are not regulated (they all are expressed everywhere) so why do some disorders affect only some parts of your body ? | askscience | https://www.reddit.com/r/askscience/comments/9syky2/why_do_mitochondrial_diseases_affect_different/ | {
"a_id": [
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"text": [
"The mitochondria plays an important role in a lot of cellular processes, some of which only occur in a specific type of cell. The least cell specific process is metabolisn; however, different cells specialize in different types of metabolic processes. For example a mutation that affects the electron transport pathway would affect the brain and muscles more heavily than the liver since the brain is constantly breaking down glucose and the liver mainly stores or releases it. A more cell specific mitochondrial function is Ca+2 signaling. In this case, cells that constantly use Calcium signaling would be far more affected. Then you have to take into account that other organelles can compensate for the lack function of another. For example, in the case of calcium release, the ER could in some cases compensate for lack of mitocondrial calcium release. \nLastly, there are the types of processes that you only see on very specific cells, such heat production in brown adipose tissue. A mitochondrial mutation that affects the thermogenesis pathway in these cells would probably have little effect on any other cells since no other cells perform the same process and brown adipose cells. \n\nI typed this on my phone so....sorry for any typos\n"
]
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[]
] |
|
15lu40 | How can radio waves be SO well spread? | I have signal everywhere I go, the gym, the mall, my three story indoor school. It's ridiculous. How does it seep in so well? And it's not just one thing, it's T-Mobile, AT & T, Sprint, Verizon, MetroPCS, U.S. Cellular, and so on. Not just a phone service either, its phone and access to the vast internet. HOW?!?! Yes, it has a low wavelength and frequency but still how can it be so powerful? And my router can't reach my bedroom closet because of the walls in the way? | askscience | http://www.reddit.com/r/askscience/comments/15lu40/how_can_radio_waves_be_so_well_spread/ | {
"a_id": [
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"text": [
"[Lots of base stations](_URL_3_). Here's a site that will [show them for your area](_URL_1_). [Here's another one that takes a while to process](_URL_2_), but it has more detailed information. In a 4 mile radius of my zip code, it foung 95 towers with 557 antennae.\n\nAlso, some [buildings have cell signal repeaters](_URL_0_), that pick up signals from towers outside and spread them around inside.",
" > And my router can't reach my bedroom closet because of the walls in the way?\n\nYour WiFi router uses much higher frequencies and lower power than are used by cell networks. It is much more easily blocked by objects in the way of the signal. \n\nIn general, the lower the frequency of a signal, the more it will penetrate (as well as 'bend' around obstacles). \n\nThus, light is stopped by as little as a thin black coat of paint while sufficiently low frequency radio waves can be used to [communicate with submarines](_URL_0_) deep in the ocean and thousands of miles away."
]
} | [] | [] | [
[
"http://en.wikipedia.org/wiki/Cellular_repeater",
"http://www.cellreception.com/",
"http://www.antennasearch.com/sitestart.asp?sourcepagename=reportviewer2&prevsessionidnum=397996696&prevordernum=1&previtemnum=1&sectionname=towerreview&pagename=towerreview&pagenum=1&cmdrequest=pagehandler",
"http://en.wikipedia.org/wiki/Cell_site"
],
[
"http://en.wikipedia.org/wiki/Extremely_low_frequency"
]
] |
|
1rlnwj | when i charge a phone, unplug it, then turn the phone off, how is the energy being stored within the phone? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1rlnwj/eli5_when_i_charge_a_phone_unplug_it_then_turn/ | {
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"Chemically.\n\nWhen you charge your battery, the stuff inside it undergoes a chemical reaction. This reaction can be reversed, yielding a current from one pole of your battery to the other when you connect them by the electronic circuits in your phone when you switch your phone on.\n\nThere are several different chemical processes that can yield a difference in electrical potential across the poles of a battery (the difference in electrical potential causes a current to start flowing when you connect the poles with something that conducts electricity). Some of them are reversible. You car battery uses lead and acid, electronic appliances use a process involving Magnesium, Nickel and Hydrogen and there is an older process that uses Nickel and Cadmium. \n\nSome chemical processes only work one way, e.g. alkaline batteries can discharge but are not rechargeable.\n",
"In the form of chemical potential energy. The phone contains a battery which contains chemicals which can be put into a position where they can be made to react in such a way as to create electrical current. The most common form right now are lithium-ion batteries, where ions are stored in a graphite negative electrode and extracted into a positive electrode containing lithium. When charging the process is reversed.",
"Chemically! The exact chemistry depends on the battery within your phone. It gets beyond ELI5 pretty fast but you can imagine it like a water pump. When you're charging its moving water to a tank at the top of a hill. When its unplugged that water can run down the hill over a waterwheel and do work again. The only difference is that the energy is stored through chemical potential rather than gravitational."
]
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[],
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||
6fj4w1 | Arthurian legends aside, were there any historical quests for the holy grail? | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/6fj4w1/arthurian_legends_aside_were_there_any_historical/ | {
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"This might not be what you had in mind exactly but meet Otto Rahn, German medievalist, SS-Obersturmführer, and Grail Hunter for the Nazis. Rahn himself is a rather marginal figure even within Nazi occultism and while commonly held that in the early stages to have been a talented historian, his name as well as his work is mostly remembered because a.) Indiana Jones had a sinister version of him on screen and b.) his work not only kindled interest in Catharism in the 1930s but were very popular among those responsible for the esoteric and non-academic Catharism revival of the 1960/70s, which gave the world the dubious basis for Dan Brown's DaVinci Code. Basically, it was Rahn who invented the connection between the Cathars and the Holy Grail.\n\nRahn was born in 1904 and studied Law, Literature and Philology in Giessen and Heidelberg. Despite there being some confusion about whether he actually finished his studies, it is certain that by 1928 he had developed an intense interest in the Cathars, an alleged Christian dualist sect in the South of France, and the Albigensians Crusade, which destroyed the Cathars in the 13th century. Developing a close relationship with French Mystic Antonin Gadal, it was during these travels that Rahn developed his theory of the Grail and the Cathars:\n\nBecause, drawing on dubious sources – as is the history of Cathars in general as [this post](_URL_0_) and [this post](_URL_1_) demonstrate – there was the theory among Rahn and people like him that the Cathars had hidden some kind of important treasure. Because Rahn had read the poetic Parzival Saga of Wolfram von Eschenbach, he became convinced that the Grail Castle mentioned in Parzival was actually the Cathar Castle at Montségur, which was the last one to fall during the Albigensians Crusade. Rahn's evidence for this was that in Parzival the Grail castle was called Munsalvaesche, which Rahn took to mean Montségur. And so, by virtue of a questionable etymological connection was born the theory that Cathars had hidden the grail from the Church and had thus been destroyed for this.\n\nOver the next couple of years, Rahn traveled Southern France and the ruins of Cathar castles and so forth to search for the Grail; a search that was abruptly ended when he was sued for being out of money and accused by French authorities of spying for the Germans. By this time, he had also become very friendly with the SS and Himmler in Germany. Himmler, who was particularly interested in medieval myth and legend to construct from them a \"Germanic\" religion rivaling \"Jewish\" Christendom, took it upon himself to further help Rahn out.\n\nRahn, who with the help of Himmler had published his bog book *Crusade Against the Grail: The Struggle between the Cathars, the Templars, and the Church of Rome* in 1934, would go on to join the SS and develop his theories further: According to him, the Cathars not only held the Grail, but the mixture of medieval heresy, grail legend, and the suppression of the Cathars in a crusade to him formed a new picture. Because of the alleged connection to Eschenbach's Parzival, Rahn posited that the Cathars were not a Christian Sect but in reality had been a Gnostic religion of Aryan-Germanic origin representing the \"original\" Germanic ur-religion, which was violently suppressed by the Catholic Church in service of the Jews. He went on to travel again to France, Italy, and even Island because to him it became clear the Cathars, the Holy Grail, the mysitcal island of Thule so popular among German occultists like Himmler, and even the Tibetan Buddhists legend of Shambala were all connected (Cathars, in his opinion being \"the Buddhists of Europe\"). He also further connected this with the World Ice Theory of Hannes Hörbinger and other, similar, BS theories.\n\nWhile Rahn's hunt for the Grail was – obviously – not successful, his books *Crusade* and *Luzifers Hofgesind, eine Reise zu den guten Geistern Europas*, both of which were barely veiled SS and Nazi Germania propaganda were hugely popular among certain esoteric and mystically inclined people, not the least Heinrich Himmler.\n\nBut while until 1938 Himmler was a huge fan of Rahn and financial backer for his hunt for the grail, in 1938 Rahn was transferred away from his research and had to perform guard duties in the Buchenwald and Dachau Concentration Camps for four months (it is speculated that this might be related to his alcoholism), after which he left the SS (allegedly because of homosexual leanings). In March 1939 a few days before his planned wedding, where Himmler would have been an honor guest, Rahn died hiking in the Tyrolean mountains. Some write he slipped and then froze while hiking, others allege he committed suicide, while still others want to see a more sinister conspiracy behind Rahn's death.\n\nWhatever it was, Rahn's dubious theories live – undeservedly – on through all the dubious literature on the Cathars and the Grail and while his Grail hunt was less spectacular than in the Indiana Jones movies – most of what he did was explore caves and spend time in dusty archives –, he is indeed one of the most recent people to have embarked on a Grail quest.\n\nSources:\n\n* Nicholas Goodrick-Clarke: The Occult Roots of Nazism: Secret Aryan Cults and Their Influence on Nazi Ideology: The Ariosophists of Austria and Germany, 1890-1935, 1985."
]
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"https://www.reddit.com/r/AskHistorians/comments/49rn50/how_did_catharism_start_develop_and_become_so/",
"https://www.reddit.com/r/AskHistorians/comments/1hione/did_any_cathars_survive_the_albignesian_crusade/"
]
] |
||
3gs46l | how is tesla doing so well while losing $4,000 per car? is that loss misleading? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/3gs46l/eli5_how_is_tesla_doing_so_well_while_losing_4000/ | {
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"i would also like to know how they are selling cars, when they arent allowed to in most states because they arent a dealership, and apparently people cant buy cars straight from the wholesaler because then they have no recourse if its bad",
"They aren't losing $4,000 per car. They sell the cars above the marginal cost of making the car, so they do make a \"profit\" on each car. But they spend that \"profit\" (and money they borrow) on expanding their business, including designing the new models, machinery and space to build the new models, and expanding the SuperCharger network.",
"Tesla appears to be doing well in what it is trying to do, which is to create demand for electric vehicles. They have created a brand that people love and a car that people want. Although they are selling cars at a \"loss\", they are betting on developments that they are investing in.\n\nIf you look at the history of Tesla, they have expanded pretty rapidly in just a decade really. In the next few years they want to create a much more cost-effective model, expand their battery production to doubling current world-wide production, and eliminate all concerns people have with electric vehicles. \n\nWe tried to demonstrate that development in a [Watson Story](_URL_0_). Hopefully it helps you make more sense of Tesla. "
]
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[],
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"http://watson-ne.ws/#/f3840e2f118a25c34b4e49bbe51ffbb9"
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||
ev7xs | GMO sequences? | Hey guys, I am doing a project involving genetically modified organisms for school and I am having trouble finding the actual sequences for the 35s promoter from cauliflower mosaic virus and the nos terminator from agrobacterium. I know these are the most commonly used promoter and terminator sequences for GMOs, but I've spent a good hour googling/ checking pubmed and ncbi for the full sequences of these and can't find them. I found articles detailing what primers they used to amplify the cmv 35s promoter and nos terminator, but no full sequences. If any of you know where to find these I would greatly appreciate the help. Thanks! | askscience | http://www.reddit.com/r/askscience/comments/ev7xs/gmo_sequences/ | {
"a_id": [
"c1b8k3x"
],
"score": [
9
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"text": [
"Nice try terrorists. Just kidding let's see what I can do.\n\nI have the full sequence of the [Cauliflower Mosiac Virus](_URL_3_). Look in the article it has a full sequence. Also I googled 35S promoter and [This](_URL_1_) was the first result. Is this what you needed?\n\nI'm having a little more trouble finding the nos terminator. I suspect Entrez is the place to start. It is definately somewhere in here _URL_2_. Try searching:\n > \"nopaline synthase\" terminator \n\nThen click \"Nucleotide: Core subset of nucleotide sequence records\"\nAaaand a few minutes of searching and I have [this](_URL_0_) Look near the end where it says \n > terminator 3731..3983\n /note=\"3'UTR of Nopaline Synthase from Agrobacterium\n tumefaciens T-DNA used as terminator\"\n\nI will leave it to you to go to the sequence and do the counting necessary to find the sequence you are looking for. (I suppose you could also use the Entrez method for the first primer if the image isn't doing it for you.)\n\nEdit: Anyone who knows how to keep that link up top from crashing will be considered greatly useful in my eyes.\n\nEdit2: RES to the rescue, link saved."
]
} | [] | [] | [
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"http://www.ncbi.nlm.nih.gov/nuccore/HI650218.1",
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1klm7z | When will we be able to industrialize graphene and when will the consumer likely see graphene in household products such as computers? | askscience | http://www.reddit.com/r/askscience/comments/1klm7z/when_will_we_be_able_to_industrialize_graphene/ | {
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"I currently work in a research lab where several members are studying the properties and manufacturing techniques of graphene. There is a lot of research in the topic right now, and this is mostly because of increased media exposure and \"buzz\" surrounding the material. \n\nThe graphene that we can grow today is small and expensive, that's the bottom line. Making large scale devices of material that is incredibly delicate is hard. You may be thinking \"but graphene is super strong!,\" and it is. But maintaining a certain phase of material at conditions we consider \"normal\" is not straight forward. \n\nOne leading researcher in the field is Dr. Jamie Warner at Oxford. Look up some of his stuff if you're interested in real science on the subject of graphene. \n\nThis is probably not the answer you wanted, but there is no good way of addressing this question. Often times research is non-linear. Also, we may or may not get to that point. There are other promising avenues for technology processing that we are exploring. \n\nTL;DR: Not anytime soon.",
"Graphene is finding its way into printing inks for functional printed electronics. The standard now is \nSilver ink at $1 a gram. Carbon ink runs $0.2 /g, but has 10x the resistance. The graphene is an additive to the Carbon, lowering the resistance to the ~~area~~ range of silver. I guess ink bulk graphene is cheaper than Silver. \n\n I think it has a good chance for replacing Indium Tin Oxide for touch displays.\n\n I work w/ printed biosensors and a few papers have been presented w/ graphene, but much more w/ Carbon Nanotubes. I have a couple 4\" sq swatches of graphene on mylar at my desk (all I need now is a client). \n\nOne last thing, safety. There is some concern now about the sharp edge of graphene slicing into lung tissue like carbon nanotubes do. No current US manufacturer wants to be in a position were they essentially have asbestos around the plant. We are trying to figure out how to address these issues before we let full scale production go on. ",
"It depends on what application you are talking about. For use as a transparent electrode material (for flexible display or solar cell applications), it seems it is being commercialized now: \n\n_URL_0_\n\nWhen you say \"in household products such as computers\", it seems like you could be referring to graphene as a semiconductor material for transistors. In this case, it seems pretty far out. If you look at this link, the international technology roadmap for semiconductors seems to say it's finFETs for the next 15 years, and then something else beyond that, which may or may not be graphene: \n\n_URL_1_",
"[This](_URL_0_) is the website of the FET Flagship Graphene, which will be funded with 1 billion € for the next 10 years.\n\nI think it's primarily for researchers, but maybe there is some information.",
"I am currently working on a well funded project on a machine that makes buckypapers, graphemes membranes and some other nano materials in an automated/continuous large form factor fashion. The machine will be finished in early September and we expect to deploy to CNT/graphene manufacturers in December. The lower cost of manufacturing that my machine offers should push more \"pure\" nano materials to market within a year or two. Graphene nano platelets and cnts with aspect ratios of 1,000-2,000 are currently available by the ton from industrial suppliers... Somewhere in the range of $.25-$5 a gram. Single wall CNT are still crazy expensive..",
"This question is problematic in that it asks us to predict the future. There is, however, an organization named ITRS (International Technology Road-map for Semiconductors) which attempts to direct industry R & D. ITRS doesn't place graphene on the map until after about 2025 from what I am aware. \n\nNow a lot of folks have talked about graphene as being a semiconductor channel material, the main functional material in a field effect transistor, but I don't predict that it will ever be used as such due the material's lack of a bandgap and subsequent low on-off ratio ( < 45 in theory under ideal conditions for perfect graphene). I predict it will see more use as an interconnect material to replace copper lines in future chips.",
"One of the major hurdles for graphene as it stands is reliably getting CVD (Chemical Vapor Deposition) graphene transfered to 300mm silicon wafers. It can be done and devices can be constructed using it but the results are very unreliable and until there is a clear way to do this there wont be any consumer devices on the market.\n\nThis goes for most applications of graphene. There are many things like obtaining single crystal graphene or high purity graphene layers to minimize surface traps. Surface traps are caused by contaminates that adsorbed to the surface of graphene or are present on the wafer. Grain boundaries in graphene are also tough to characterize and predict.\n\nSo there is still alot of work to be done with graphene and from a view of a person surrounded by many many researchers working with the stuff it will be quite some time (possibly more than 10-20 years) until graphene is a reliable conductor/semiconductor for modern devices. ",
"In addition to this question... \n\n**What products are people most excited to see material like graphene used in?**\n\nI ask because some of the coolest uses I've heard about is carbon nanotubing with graphine support to help stitch broken bones back together nearly instantly and without needing any brace for support. My college was working on this process as I was attending and found it amazing that you could have a broken bone stitched back together like a welder fixing a bend/broken pipe ",
"Sorry, but what exactly is graphene?",
"They currently sell graphene heatsink grease for CPUs. I use it.\n\nIt's actually of little difference to Arctic Silver heatsink grease (which uses silver particles), but it's much cheaper.\n\nThe grease media the silver/graphene particles are suspended in is the limiting thermal factor. The Arctic Silver's silver is already trivial thermal resistance in the silver itself, so no gains in going with something of much lower thermal resistance. Except cheaper!",
"I just want to point out something that hasn't been mentioned. I hope someone who knows better will provide more accurate information.\n\nBut months ago I saw a video of a dude who used a standard laser inscriber to produce small pucks of graphene. He ground up graphite, spread it on top of a disk with water and then zapped it. Does this technique produce inferior graphene, or what? Because to me it seems like this could be done on a large scale for fairly cheap. ",
"In the 1967 film, The Graduate, someone tells Dustin Hoffman character to put his money in plastic. That sounds like sage advice given our use of plastic for the last 40 years or so. \n\nSo, what I want to know is when should I start putting my money into graphene? ",
"I used to work in a research lab at a university doing research on graphene. I'll answer a few of the questions people have asked here and then give my opinion.\n\nGraphene is basically just plain carbon. The atoms are the exact same carbon atoms in diamond, graphite, coal, the \"C\" in CO2 etc. The special thing is how they are arranged.\n\nIn diamond, the atoms are arranged in a 3d tetrahedral structure, which gives diamond its strength. In a sense, you can think of a diamond as a single molecule, as all the atoms are bonded together through each other.\n\nIn graphite (the black form of carbon), the carbon atoms are bonded together in 2d hexagons, kind of like chicken wire. These 2d sheets are then stacked together to make a 3d chunk of carbon.\n\nThe nice thing about graphite is that while the atoms in the sheets are bonded together very strongly, the sheets themselves are very weakly bonded together. In this way, graphite is analogous to a stack of paper. The individual sheets are strong, but you can very easily separate the sheets from each other. Graphene is the name given to a single sheet of the form of carbon that makes up graphite.\n\nThe first discovery of graphene involved essentially sticking a little flake of graphite on a piece of scotch tape, then repeatedly sticking and peeling the scotch tape apart. Upon the first stick and peel, the graphite was split roughly in half in thickness. Each successive stick and peel split the graphite roughly in half again. It doesn't take long before you've split the already thin flake into pieces a millionth the thickness of the original.\n\nThere's some follow up stuff you have to do later with silicon wafers, microscopes, and lithography, but the \"making\" of graphene was essentially this and was called the scotch tape method. This method produces very high quality electronic samples, but most are just a few microns in size. Good sized ones can be tens of microns, and if you're really lucky, you might find one that gets close to 100 microns. We won't be making your next CPU out of scotch tape graphene.\n\nThere are 2 other methods of producing graphene that I am aware of, but it has been a while since I've done research on the material.\n\nThe second method is CVD (chemical vapour deposition). Essentially you take a wafer of silicon, coat it with a metal like nickel or copper, heat it up to a few hundred celsius, and put it in a low pressure microwave plasma chamber. You flow in methane gas, apply microwave radiation which breaks the methane up into carbon and hydrogen, and the carbon slowly dissolves into the metal layer. Once you've reached the solubility equilibrium of carbon in (copper, nickel) at a given temperature, you stop the plasma and cool the wafer. The carbon surfaces and forms a thin layer on top of the metal. If you get all the parameters right, it'll form graphene.\n\nThis method holds a lot of promise for producing large sheets of graphene, but from what I last saw, it was producing sections of graphene 1 layer thick in and amongst other sections of 2, 3, 4+ layers. Cool, but not quite good enough.\n\nThe third method is sublimation of Si out of an SiC wafer. You can get wafers of crystalline SiC (called Moissanite I believe) that are similar in properties and appearance to diamond. You put the wafer in a vacuum chamber, heat it up, and the silicon from the top layer sublimates out (boils off basically), leaving a layer of graphene on top of the SiC. This method might work as well, but SiC isn't super cheap and it also doesn't produce huge sheets of monolayer graphene.\n\nAs to when it will be useful to consumers, well there are two problems we have to solve. The first is this question of large scale production. The second is that graphene doesn't have a band gap. In order for a semiconductor to be useful, you have to be able to turn the conductivity off. You can't turn graphene off right now. It's a good conductor, and that has a lot of uses, but in order to be very useful, we have to figure out how to produce a band gap.\n\nWe kind of know theoretically how to do it (doping, forcing a lattice asymmetry by patterning a superlattice or strain or something), but we don't know how to actually do it yet.",
"I'm a young man looking to invest in graphene. What companies would you say are leading the way in R+D and would be advisable to invest in before they \"takeoff\"",
"graphene has inspired research into other 'atomic mono-layer sheet' (2-D) materials with more useful semiconductor properties than graphene. A 2-D material that resembles commercial semiconductors much more closely is molybdenum di-sulphide (MoS2), and this is the tip of the iceberg. \n\nTo put graphene into perspective, i'm a researcher at a top-10 US research university where cutting edge electronic and optoelectronic semiconductor materials have had various sized research groups exploring a wide variety of materials in groups of 2-3 people up to groups of 40 for the most well-funded semiconductor materials (during the cold-war when funds flowed freely). Research monies in most of these fields have dried up - this means researchers are conducting their present small scale research while seeking other greener pastures for future opportunities.\n\nThis large group of highly trained, underutilized, sold state scientists and engineers are constantly on the prowl for new research opportunities. This transition is commonly replayed in hundreds of research universities in the US and worldwide.\n\nThen along came graphene.\n\nThere are presently more 100 researchers funded, or proposing funding for graphene research at this university. The impact of graphene measured by the number of researchers working, or proposing graphene studies is dramatically higher than the last two most popularized solid state materials breakthroughs - high temperature superconductivity in the the 1980s and cold fusion in the 90s.\n\nThis focus on graphene by so many researchers is partly driven by the unique properties that need to be understood and controlled, and partly by 'the last great hope for funding by proposing trendy work' for this army of solid state scientists who have no other place to turn for topics in research that are more potentially fundable.\n\nGraphene will find early adoption in niche products as manufacturing control improves. The ideas expressed about insertion into the auto industry are particularly naive. It is more difficult to get automakers to adopt new technology (because of potentially catastrophic costs associated with manufacturing defects) than smartphones, games and even military customers. \n\nGraphene is Kool, but the 2-D technologies it has inspired will sooner/eventually occupy a greater shelf space at Walmart"
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aupioy | if we can't get under 7nm with silicon why are intel/amd not building bigger dies with more transistor instead of always shrinking? | If a regular CPU consume 95W today in 14nm, why aren't they building HUGE cpu that consume 3-400 watts? all we would have to do is having a bigger PSU and more efficient cooling. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/aupioy/eli5_if_we_cant_get_under_7nm_with_silicon_why/ | {
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"Because heat is a never ending enemy, and you'd have to find a way to dissipate all that heat.\n\nPlus you only need a certain number of transistors to do each instruction. More transistors doesn't make your CPU faster. Smaller transistors do - because they generate less heat, meaning you can run them faster while keeping them cool enough.\n\nYour solution is only feasible in the sense of adding more cores - which doesn't make each one faster, but does allow more parallel computing - if the computations are paralellizeable.",
" > why aren't they building HUGE cpu that consume 3-400 watts? all we would have to do is having a bigger PSU and more efficient cooling.\n\nBecause it will generate a metric ton of heat. Like, a lot. Which means a big ol' heatsink and a noisy, high RPM fan. Your power user might use liquid cooling to make this more efficient (which would also mean using larger fans which mean lower RPMs for the same airflow which means more quiet) but this isn't practical for Joe Consumer or Joe Business User. Furthermore - did I mention it will generate a ton of heat? \n\nUsing a processor that was 125W stock and close to 200W overclocked in a ~10-14' bedroom that would normally be 68 degrees in winter, in a few hours it would heat the room up to about 78 degrees and I'd have to open my window in the dead of winter. Now try generating 2-3 times as much heat. Oof. \n\nAlso, energy isn't free. An extra 305 watts for 8 hours a day is 890.6kWh in a year. The average price americans pay per kWh is 12 cents, which means you're spending an extra $106.87 a year on energy.\n\nFinally.... Why NOT continue to reduce die size until we've hit practical limits? More efficient means you can get the same performance for less heat/power... Which means you can get even MORE performance if you overclock it a bit.",
"We're about at the limit for electricity traveling between two sides of the die in one clock cycle already. You can get around that by adding more independent cores, and localizing resources so electricity never has to go too far, but I think a few things would need redesigned for that.\n\nAdditionally, the current chip fabrication process has effectively randomly distributed flaws throughout the die. The larger the die, the higher chance of a ruining flaw to be present making the chip useless. This, however, is changing with something called \"chiplets\" where chips are made of individual parts \"glued\" together.",
"First, we can indeed get below 7nm. There are plans for 5nm and even 2nm in the future.\n\nThe real reason they don't want to produce larger CPUs is due to cost. The cost of manufacturing a single silicon wafer is pretty much fixed. The more CPU dies that they can get out of each wafer means that each CPU is cheaper."
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qn6mj | At what point in evolution on earth did cells or their earlier counterparts begin to have a drive for survival, and want themselves and their descendants to become more numerous? How did this evolve? | I was wondering at what point did cells suddenly think that "Me and my descendants deserve to be here more than everyone else on earth", and start evolving to outcompete other cells. Has this competetion always been there?
I was wondering because without this drive for survival, evolution by natural selection would not happen. | askscience | http://www.reddit.com/r/askscience/comments/qn6mj/at_what_point_in_evolution_on_earth_did_cells_or/ | {
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"Err, cells can't actually think. They don't 'want' anything or have a 'drive' for anything. They don't 'decide' to evolve. Evolution isn't something an individual does, it's something that happens over generations and generations in a population. Random mutations occur, and by natural selection, the mutations are beneficial to propagation mean those traits propagate, while the ones that aren't beneficial, don't. It's not a goal-driven process, much less any kind of conscious one. \n\nHere's an analogy: Pick a random card from a deck. Now let's have a selection rule: If it's not a king, you put it back, otherwise you hold it and draw a new card. Repeat this a thousand times. You'll likely end up holding four kings. Now, would you say this is because those cards decided they 'wanted' to stay in your hand and became kings in order to do so?\n\n",
"There is no \"think\" \"deserve\" \"drive\" for anything in organisms so simple; forethought or planning of any kind is not possible.\n\nThere is a bit of \"cart before the horse\" type thinking here, I think. Natural selection and evolution are things that *happen to* populations, not things that populations *do*. \n\nEven non-living mechanical systems or computer simulations can demonstrate \"natural\" selection (there are literally fields of study dedicated to this concept), would you say that a computer program has a \"drive for survival\"?\n\nedit: computers can do \"natural\" selection, not natural selection",
"I think it's best answered very simply. Life is a self-replicating chemical reaction. Chemical reactions that don't self replicate - end.\n\nIt's a requirement that if you are alive, you haven't died already. The self replicating chemical reactions that have made it this far are pretty damned good at staying around. Natural Selection favors those with a never say die attitude. "
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3e4rzi | why do conservative supporters always say "the problem with socialism is you eventually run put of other people's money." when socialism is brought up | Especially when evidence shows that socialism works in various European countries
Run out* | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/3e4rzi/eli5_why_do_conservative_supporters_always_say/ | {
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"Exactly which European countries does socialism work in? It's a matter of degree. No EU country is as socialist as Marx would have designed. Some countries have high taxes to provide high levels of service to small populations. None of those countries has open imigration. None of those countries have scaled socialism to the size of the US economy. For a small enough place, many things are possible that don't scale.",
"It's an easy statement to dismiss something without actually having to bring up any arguments.\n\nAn equivalent inverse statement would be : \"The problem with Capitalism is that eventually one person owns everything.\"",
"In many cases, it seems like these people don't pay any attention to anything happening outside their own country. The whole healthcare reform thing was a perfect example of this. You had people getting hysterical about \"government death panels\", without taking a second to look around and see if this was, you know, something that *actually happened anywhere* in places with different health insurance models. ",
"one element of it is a moral attack, because people advocating socialiims are often demanding the transfre of property from others to themselves.\n\nIt is prodding the common tendency of socialists to not adequately explain how they are paying for what htey want(or more likely, forcing someon else to pay for)",
"That was actually a Margaret Thatcher quote, saying that socialist governments generally nationalize industries one by one until there's nothing left. \n\nso why do people use it? Because it's a nice quote from a famous person and people like to use these. ",
"It's just a hackneyed cliché, and makes no sense if you think about it. Why would you run out of money? People have to pay tax. Why is it \"other people's\" money? It's our *shared* money. "
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510xup | how to mathematicians make a living? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/510xup/eli5_how_to_mathematicians_make_a_living/ | {
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"Most mathematics research is done by professors or graduate students at universities.\n\nProfessors get paid a salary in exchange for doing teaching and research. Solving famous mathematics problems gives their university prestige and attracts the best graduate students.\n\nGraduate students in mathematics, science, and engineering get paid a stipend, too. A typical stipend at a U.S. university might be $30,000/year - not a lot, but plenty to live on. Graduate students aren't suppose to take any jobs other than teaching, they're supposed to spend all of their time on research.\n\nThere are also private research labs, and researchers who work for big companies like IBM and Google. For the most part, those researchers tend to work on more practical problems that have real-world applications, not things like the Millennium problems that are interesting and potentially useful someday, but have no immediate practical application.\n",
"Mochizuki's proof/entire new theory is not the norm, at all. \n\nMathematicians (by which I will mean pure mathematicians - those who research mathematics itself), by and large, are paid to do research by either private companies or government funding. Governments have budgets for scientific and mathematical research for the advances they make which may benefit society in the long run - paying for this research is justified by thinking of long-term gains. Most finding I am aware of comes from the budget of the research councils. In the UK, mathematicians would apply to the EPSRC. Private companies on the other hand, have typically more focused views, yet happily pay for wider research. For instance, the NSA and GCHQ facilitate research into number theory, since it's vital for cryptography. \n\n\n\nNow what about Mochizuki? Well, he's a special case indeed. Mathematicians are generally very smart people, but there are some whose insight and creativity are simply outstanding. Mochizuki is one of those people. He's come up with a completely new approach with which he believes he has solved the ABC conjecture. He published this work in a series of 4 papers in 2012, and it's been reviewed by many mathematicians (in particular, my algebraic geometry lecturer! Who, by the way, believes Mochizuki's theory is indeed correct). I'm not sure when exactly \"they'll\" (the mathematical community) will accept it as true, since there already are a few mathematicians who've read and checked the hell out of it and haven't found any flaws and think it's fine... but anyway, these people who are doing the checking have their own research going, in more productive areas (i.e., more is getting published), which in turn makes you a better candidate to receive funding (hence the saying, \"publish or perish\").\n\nContrast this to Andrew Wiles, the guy who proved Fermat's Last Theorem back in 1994/5. He was a professional mathematician, but his work on FLT he did at home, by himself. Strictly speaking, that work wasn't \"his job\", but more his burning desire after seeing a vague method of approach he believed he could complete (which he did, but it took him 7 years!!). So as you might've thought, nobody paid him to sit around and try to solve some really really hard and old problem. \n"
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29xla9 | what determines if someone is "hot-blooded" who loves the cold or "cold-blooded"who loves the heat? | If there is such a thing (which I believe there is), what determines this? My whole family is "hot - blooded"where we love the cold and despise the heat. While some of my friends are the exact opposite. | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/29xla9/eli5_what_determines_if_someone_is_hotblooded_who/ | {
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"It has to do with our ability to adapt. I currently live in Oklahoma and every year we go through the summers with unbearable heat and then winter rolls around and it's ridiculously cold. But by the time the seasons begin to change from one extreme to the other we have adapted and have to re-adapt. Some people are more inclined to adapt to temperatures better than others, and I think that does have something to do with genetics of the people in certain areas."
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3gwriz | the missile knows where it is because it knows where it isn't. | [For reference](_URL_0_). I saw this again today for the first time in several years, and if I understand correctly, it's not a gag. So: ELI5? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/3gwriz/eli5_the_missile_knows_where_it_is_because_it/ | {
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"The principle of inertial navigation is to track relative motion and accumulate (or integrate) towards a goal value (the target). The video is the sort of explanation we try to avoid in ELI5, it's literally treating you like you are 5, and it comes across as pretty condescending. It's not a gag, just inept.",
"Its a very confusing way of saying \"if you know where you're going (where it isn't), and how to get there (the difference or deviation), you can figure out where you are\".\n\n\"The variation\" just means the missile got lost for a little bit, but it can fix that.",
"This is what happens when you let your geekiest programmer write the script. You get words that are technically correct, but don't mean anything to people who don't already understand them.\n\nWhat they're trying (failing) to describe is a system that notices when the missile deviates from its intended path, and then makes corrections until the deviation reaches zero.",
"Its an odd way of describing a PID controller. Basically the PID controller will use math to smoothly bring an input (where the missile thinks it is) towards another signal (where the missile wants to go). The size of the difference can be thought of as the missile knowing where it isn't (it is 'this' far away from where it wants to be).\n\nThe strange wording for the video is trying to convey that the values can be positive or negative (think left v right, or up v down)."
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6qyhcn | how exactly does a us president "push legislation through congress?" | I always hear people say things like "Johnson was able to push the Medicare program through Congress," but what exactly does that mean? Is it just a matter of the President verbally pressuring representatives, or are there certain concessions that are made? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/6qyhcn/eli5_how_exactly_does_a_us_president_push/ | {
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"Both. They can tell members of Congress that future favors are coming if they agree, and that if they don't agree the President will not support their own pet ideas.",
"The president has a lot of soft power, power that's not explicitly stated anywhere but that still exists. So for example, the president is the de facto leader of their political party and can do things like instruct the party not to support the candidate's reelection. He or she can also do some favor trading, such as offering his or her voice of support for a senator's pet project or promise not to veto some other bill that a senator from another party might be trying to pass. And he can also petition Congress directly by insisting that some legislation is good for the US people. This used to be a lot more effective 50 years ago or so, when the two parties were measurably less polarized. It can still sometimes be effective today, since the President can appeal directly to the people through the media.\n\nNowadays the bargaining version is a lot more common.",
"A few different methods. Some, like Johnson, were in the legislation and can apply personal or political pressure on representatives. They might also get people who work for them to help congress draft legislation that would satisfy various groups of people and had a higher chance of passing.\n\nThe president also is the de facto leader and very visible face of a political party. They get a lot of media attention, and can make a certain topic get a lot of coverage by giving speeches, having allies talk about it in the media, or (in the modern era) talking about it online. This puts public pressure on people in congress to do something about that topic.\n\nFor example (leaving aside whether or not you think it's a good or a bad thing!) Donald Trump spoke quite a bit about how terrible \"Obamacare\" was, and how congress should pass legislation to repeal or change it. Every time he would tweet about it, or speak at a rally, more people heard that message. People who like or agree with him as a politician are now likely to put pressure on their congresspeople to vote on something that fulfills that. In Trump's case, he arguably didn't do as much to push the legislation as other presidents have done--and he also isn't particularly popular relative to other presidents, both of which may have contributed to the health care bill failing.\n\nAnother thing presidents have, and their only constitutional power in this matter, is the power to veto a bill that has been passed. This doesn't tend to happen, but the president could state that he or she won't sign any other legislation until they vote on whatever legislation they are trying to push through. \n\n"
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p6cc0 | When you wake up late and don't remember turning off your alarms, what actually occurred? | Regardless of the number of alarms I put up, many times I wake up late and find that all my alarms have been turned off, though I have no memory of it.
Which situation is actually happening. Did I wake up, consciously turn them off, go to bed, then forget about it? Or was the whole process unconscious as part of the brain isn't operating? If it's the latter, is it caused by sleep deprivation alone? Because I get more than enough sleep, but still experience this | askscience | http://www.reddit.com/r/askscience/comments/p6cc0/when_you_wake_up_late_and_dont_remember_turning/ | {
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"Something horrible happened here. I'll just leave this link directing you to a [past post](_URL_0_) that may be helpful."
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5kruau | Are there any books that specifically deal with how medieval cavalry was used? | By this I mean, are there any books that look at the role of cavalry in warfare and how they were used in scouting, how charges were made and what their tactical role was? I know that there are a few books out there which deal with horses, their equipment and their social role/value, but I don't know of any that detail their actual use in warfare. | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/5kruau/are_there_any_books_that_specifically_deal_with/ | {
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"For Norman and Anglo-Norman cavalry warfare, I would look at R. Allen Brown's \"The Status of the Norman Knight\" and \"The Battle of Hastings\", both located within Strickland's *Anglo-Norman Warfare: Studies in Late Anglo-Saxon and Anglo-Norman Military Organization*. Hell, I would just look through the entire book (it's a collection of related essays and papers, not a monograph) if you can at all easily find a copy. I'm not aware of any really good books that cover medieval cavalry warfare writ large; such books tend to result in generalizations by non-experts."
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4djk6g | What is happening in a light bulb on a quantum scale? Is it really just turning electrons into photons following The Conservation of Energy? | [deleted] | askscience | https://www.reddit.com/r/askscience/comments/4djk6g/what_is_happening_in_a_light_bulb_on_a_quantum/ | {
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"Electrons are not turning into photons. What's happening is that a current of electrons is running through a wire similarly to water running through a pipe. However, this heats up the wire, since the wire has some resistance. Eventually, the wire is hot enough that it glows.\n\nThe energy to heat the wire comes from the fact that the electrons enter with a higher energy, and leave with a lower energy, and that lost energy is due to the heating of the wire.",
"The current running through a filament (typically made of tungsten) in an incandescent bulb causes energy to be transferred to the tungsten atoms. This energy transfer causes electrons in the tungsten atoms to be promoted to higher energy orbitals. These higher energy configurations of tungsten atoms are not stable, and the electrons will spontaneously collapse back to lower energy orbitals, giving off photons with energies (and wavelengths) corresponding to difference between excited and non-excited energy levels in the process. \n"
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117ukm | How long can we expect the Mars Rover (and other manmade objects) to remain on Mars? | Would they still remain mostly intact after millions of years barring any meteor strikes? There is only a trace amount of oxygen, so I wouldn't think corrosion would be much of an issue. | askscience | http://www.reddit.com/r/askscience/comments/117ukm/how_long_can_we_expect_the_mars_rover_and_other/ | {
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"They'll be there at least for tens of thousands of years, we have evidence of early metal tools from here on Earth that have survived that long relatively in tact with, as you pointed out, more corrosive conditions. It's hard to say with much accuracy but there are certainly materials on the rover that wont erode or corrode much over a span of even hundreds of thousands of years and so it's very possible that at least some remnants of them will remain over the course of a million or more. ",
"The question, at least to me, is a little vague. Do you mean operate? That's purely an issue of the solar panels not being able to take in energy anymore.\n\nBut remain, long past their operations cease? This is an issue of whether or not the Dust storms on Mars take an extremely long time to erode the materials. Dust storm velocities on Mars have been observed at around 80 - 120mph. Since the atmosphere of Mars is about a sixth of a percent of what we could expect right outside, it would carry less energy. However, in part due to the weak atmosphere just mentioned, the amount of dust that would be carried up would be a whole lot more. \n\n\nThese dust storms are a major scare to NASA as they try to land more and more probes on to the Maritan surface.\n\n\nIt wouldn't be an extremely long time. "
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a4qath | Does the geometry of an atomic nucleus affect its stability? | I recently learned that some highly-stable elemental isotopes, such as Calcium-48, have highly-spherical nuclei. The source I heard this from seemed to imply that these characteristics are related, so I'm wondering if that is truly the case, and if so, why is that so? From my rudimentary understanding of nuclear physics, I might guess the spherical geometry somehow maximizes favorable interactions like the exchange of pions between protons and neutrons - am I at all on the right track here? I've previously only learned about nuclear stability in terms of the number of protons and neutrons, regardless of spatial configuration. | askscience | https://www.reddit.com/r/askscience/comments/a4qath/does_the_geometry_of_an_atomic_nucleus_affect_its/ | {
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"Yes, the shape of a nucleus does generally affect its stability. From the liquid-drop model, you can see that there are volume and surface terms that both contribute to the binding energy.\n\nIn an extreme case of something very deformed and with a high Z, the deformation makes it more susceptible to spontaneous fission than something more spherical.\n\nThere are special cases where two significantly different shapes of a given nucleus are close in excitation energy. This is called *shape coexistence*.\n\n > I might guess the spherical geometry somehow maximizes favorable interactions like the exchange of pions between protons and neutrons - am I at all on the right track here?\n\nYes, the NN interaction is short-ranged and usually attractive, so nucleons like to stay close together if possible. This is why the surface term exists in the liquid-drop model, it tends to increase binding energy when the nucleus is closer to spherical. Of course truly spherical nuclei, like calcium-48 in the ground state, are a very special case. Many nuclei are in fact deformed in the ground state, and this is due to residual interactions between the valence nucleons and/or the valence nucleons interacting with the core."
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68anu4 | why can't we fly a plane as high as it can go and launch a rocket off the back of it, using less fuel and weight, plus using the momentum it already has with the plane? kinda like a giant missile to space. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/68anu4/eli5_why_cant_we_fly_a_plane_as_high_as_it_can_go/ | {
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"You would still need so much fuel and such large rockets that there are no planes even close to big enough to do what you are suggesting. It would take a truly massive plane to make this work.",
"Because the plane adds almost nothing to the momentum of the rocket, and because the planes we have are too small to give a significant payload to the rocket once you factor in the need to load it up with close to the same amount of fuel as you would in a normal launch.\n\nThe hard part isn't getting to orbit, but getting a high enough speed to maintain that orbit. For example, the Space Shuttle had to hit 17,500 mph relative to Earth's surface; putting it on top of a plane would have only accounted for the first few 500 mph or so, and would have severely compromised the payload.\n\nGranted, you can try to get the plane moving faster, as what you're talking about has *some* merit, but the US hasn't tried anything like what you're suggesting since the [MD-21 incident](_URL_0_).",
"A transport plane might get to roughly 500 mph with a rocket strapped onto it. The velocity needed to exit Earth's orbit is around 17500 mph. That's less than 3% of what it would need. You'd also have to make the plane really powerful and the rocket very small and light-weight to even be able to lift it off the ground.",
"It is called Pegasus and run by Orbital ATK\n\nThey have been doing it for awhile\n_URL_1_\n\nHere is a recent launch\n_URL_0_",
"You actually just described Spaceship One - _URL_0_",
"We can but it is not terribly practical.\n\nIn very rough terms lowest possible orbital speed is about 25,000 km/hr. A rocket achieves that by throwing mass out the back and letting conservation of momentum do its thing. The difference between a rocket and an (airbreathing) jet engine is that all the propellant mass has to be aboard at the beginning of the flight to accelerate not just the payload but, at earlier stages of the flight, all the rest of the propellant too resulting in the Tsiolkovsky rocket equation. As a result, the F9 requires about 500,000 kg of fuel to raise 20,000 kg to LEO. \n\nAn extremely fast aircraft (SR-71) might achieve 4000 km/hr with a few hundred kg of payload and mid-air refueling. A B-2 goes about 1000 km/hr with about 18,000kg payload (again with mid-air refueling).\n\nNow if you look at the numbers above you can see that, from a speed perspective, a jet aircraft is roughly stationary compared to an orbiting spacecraft. You can also see that a rocket small enough to be carried by a B-2 would only be able to lift a few hundred kg to orbit and that it doesn't make much difference (at least in terms of momentum) whether you launch that rocket from the surface, from a balloon or from a jet aircraft.",
"The most energy is used to get the necessary sideway speed for the satellite. \nWhen you launch an Object near the equator it'll already have around 1650km/h of sideway movement (40000km/24hr). \nmuch more than you could add with a plane and still only a fraction of the needes speed",
"You could push your car by hand to get it rolling, then use the motor.\n\nAnd, you could push a booster by using an airplane, then use the rocket motor.\n\nIt's about the same thing.",
"That's what we (Firefly Space Systems) were trying to do. The advantages of an air launch means there is a lot lower max Q during the launch so a lot less stress of the vehicle, the ability to launch anywhere and not be tied to a launch pad, and faster turn around between launches. The downside to launching any sizable vehicle is weight. Do you plan on launching something small like a Pegasus (do-able) or a Falcon 9 (impossible) from a plane? Our rocket was designed completely with carbon fiber to reduce weight, and even with that, we needed the largest plane to ever be build in order to do that (Stratolaunch). ",
"Why not just replace the plane with a rocket? And you've just invented the multi-stage rocket.",
"The answer is, we totally can, and have! But... it's only a good idea in a very few situations. \n\nThere are two reasons why air launch is even worth thinking about. First, it's an easily reusable first stage. No worries about parachutes bringing down parts of your rocket into the ocean (Like the space shuttle boosters), or the extra complexity of having your first stage land (Like the falcon 9, which wasn't reusable until very recently).\nAnd second, aircraft use air breathing engines, which have a higher isp (efficiency per weight) than rocket engines. Which theoretically means less fuel required for launch.\n\nNow for the downsides: as other people have said, the biggest part of getting to orbit is the velocity you need, not the altitude. In fact, the studies I've seen points to a \"best case\" air launch at 40-50 thousand feet altitude, 30° upwards, and as fast as possible. Going higher doesn't add any benefit, going faster does. Now you're talking about dropping a rocket off of an aircraft at speeds above mach one, which is not an easy feat.\n\nSecond, you're limited on payload size. An aircraft that could replace the first stage of a falcon 9 would be so absolutely massive it's no longer practical (which is what Elon Musk was referring to when he said air launch wasn't worth pursuing) \n\nEven then, unless your payload is small enough that an existing airframe can do the lifting, you're now designing a rocket AND and aircraft. Are the performance gains worth twice as much work? And using existing airplanes isn't an easy cookie cutter solution. Even bomber aircraft can't hang all of their possible payload from one location, and their strongest mounting points are on the fuselage: the part that's closest to the ground during takeoff. It just makes it hard to physically squeeze a vehicle on.\n\nIt's possible, but there are a lot of weird little things to figure out, and it has discouraged most of the people looking into designing a launch vehicle system. "
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63kv0c | why have 'google' and 'photoshop' become verbs, but 'amazon' or 'wikipedia' haven't? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/63kv0c/eli5_why_have_google_and_photoshop_become_verbs/ | {
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"Not sure the reasoning, but I've definitely heard/used \"wiki\" as a verb. \"I'm gonna wiki that to see if it's true\"",
"Necessity of a symbol. Language folows the need to express ideas efficiently. If there is an idea that doesn't have easy expression, people will make new word for it. There was no verb that described \"searching on the internet\". So googling took that spot and became shorthand word for \"searching on the internet\". earching on the internet is significantly different than searching in real life so the new word is justifiable. Similar with Photoshop but there already is a word for buying stuff and buying stuff on the internet isn't different enough to justify making amazoning into a word.",
"Both google and photoshop created entire new categories of behavior that needed verbalizing. Amazon is a store and wikipedia is an encyclopedia."
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b7fxlc | why do criticality accidents never result in a nuclear explosion? | Accidents like the Tokimura nuclear accident make sense because the fissile materials are in an aqueous solution, and the solution boils off when too much heat is introduced, creating void space and preventing it from remaining at supercriticality.
But the demon core was a plutonium core meant to be in an atomic bomb? There's nowhere for void space or neutron absorption, it was a solid core of plutonium (as far as I know). How did that not sustain supercriticality long enough to cause a nuclear explosion? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/b7fxlc/eli5_why_do_criticality_accidents_never_result_in/ | {
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"Nuclear reactors keep the fuel too spread out, with too much neutron-absorbing material in between, to become an atomic bomb.",
"The criticality accidents with the Demon Core only pushed the core slightly into the super critical region. If left in that state it would have emitted tons of radiation and gotten really hot until it all melted and spewed apart.\n\nThe Demon core was basically identical to the core of [Fat Man](_URL_0_), both were 6.2 kg plutonium spheres, so why didn't the Demon Core go KABOOM like Fat Man? Because the core wasn't squeezed. While both cores reached the supercritical state, the core in Fat Man was squeezed by explosives which pushed it deep into the super critical region causing its chain reaction to propagate much much faster than the Demon Core's until it blew itself apart a few milliseconds later.\n\nGoing supercritical just means that a hunk of radioactive material is releasing more and more power over time. That could mean that the power output has increased from 2 W/kg to 3 W/kg in a second or that it has increased from 2 W/kg to 1x10^15 W/kg in 100 milliseconds, both would be deemed \"supercritical\" but only the second one vaporizes buildings",
"When nuclear material, such as the Demon Core, go supercritical, they generate a LOT of heat, which causes them to expand. The expansion is enough to end the supercritical state. \n\nTo achieve an explosion, the supercritical state has to be maintained as long as possible to permit a runaway reaction. This is not possible with mechanical means. The bomb core is compressed using the shockwave from a conventional explosion. This all happens in milliseconds, but that's long enough for the sustained runaway reaction to generate ungodly amounts of heat and radiation. ",
"It needs to go prompt supercritical with enough reactivity to result in an explosion. \n\nThe demon core needed a specific firing mechanism to raise reactivity fast enough and high enough. The reflector in the experiment merely made it delayed critical, the same as a power reactor startup. It was not designed to generate enough reactivity to go prompt critical under those conditions. "
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p7pz9 | What are some common causes of static electricity outside of the widely known factors (i.e., wool sweaters, etc) | askscience | http://www.reddit.com/r/askscience/comments/p7pz9/what_are_some_common_causes_of_static_electricity/ | {
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"What are the widely known factors? This [link](_URL_0_) describes the action by which static charge builds up on people. I wasn't aware how it worked when I was told about it in a lecture a few years ago.",
"static electricity is caused by a charge imbalance between two materials. most things are electrically neutral in a normal state, but when certain materials come in contact with each other electrons from one can be transferred to another. the material with extra electrons will have more negatively charged particles than positively charged particles (protons), and vice versa for the material losing electrons.\n\nMost materials can effectively neutralize this imbalance by transferring extra electrons to the ground, but occasionally with materials which have a high resistance to flow of electrons (stuff that would be considered an insulator) the charge imbalance can remain in the material until it comes in contact with someone else that needs to either take its extra electrons or give away its excess electrons.\n\nany two materials in which one is a good electrical insulator can be used to create a static charge. if both are insulators that is even better. Some materials like leather, fur, glass, cotton, silk, paper, and hair will always give away electrons. Others likerubber, teflon, vinyl, cellophane, polyethylene--most plastics--will always take electrons. an insulator which gives electrons combined with an insulator which takes electrons will create the most dramatic imbalance and therefore the best static shock."
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1x0ilz | When a Phase Change Occurs Because of Pressure Change (e.g. flashing of water), Does The Temp. Remain the Same? | I was reading about the effects on the human body when exposed to near vacuum conditions (such as in space). When NASA testing this, their test subject reported the last thing he remembered before he began to lose consciousness was the water on his tongue beginning to boil.
I assume this is because of the pressure of the water was below 1 atm and was beginning to change phase to a liquid? Would that be that be correct to assume? I imagine if, while the water was beginning to boil due to pressure, that if the temperature also changed it would probably be pretty painful. | askscience | http://www.reddit.com/r/askscience/comments/1x0ilz/when_a_phase_change_occurs_because_of_pressure/ | {
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"You are correct, the water on his tongue boiled because the pressure was so low. The [phase diagram](_URL_0_) of water shows the thermodynamically preferred state of water for a given combination of pressure and temperature. Assuming the test subject was in a near vacuum the boiling temperature of water in his conditions would have been about -60C. This doesn't mean the temperature on his tongue would have plummeted to -60C however, it does mean that the water on his tongue would continue to boil as long as the temperature was above that. Since boiling is an endothermic process his tongue would get colder as heat was absorbed by the boiling water. But i'm guessing his tongue would dry out before any painful amount of temp change occurred (assuming he was conscious...). Using low pressure to boil a liquid is actually frequently used to reach very low temperature, check[ this video](_URL_1_) out."
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1w3xmp | Why is Los Angeles so far from the coast? | LA is near the coast but why isn't downtown built directly on a port or navigable river like most big coastal cities? | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/1w3xmp/why_is_los_angeles_so_far_from_the_coast/ | {
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"There are no navigable rivers in southern California, so that was not an option. The area of downtown was inhabited by the Tongva people when Europeans arrived in the early 16th century. About 90% of the Tongva diet came from the acorns of the California Live Oak. The acorns are toxic unless they are painstakingly crushed and thoroughly washed, so the combination of the downtown oak groves, nearby the Los Angeles River, made a perfect place for this process. When Europeans moved into the region they settled in the same area for the same reasons, access to water and trees (for building supplies and shade). Another possible reason why they did not settle closer to the ocean, is strong botanical evidence that Los Angeles was not the dry place we think of today over the entirety of its history. In fact the low-lying areas of the Los Angeles basin are still today a seasonal floodplain, and there is evidence that as recently as only a few hundred years ago parts of the Los Angeels basin supported wetland grasses which need standing water year-round. This could partly explain why most of the Los Angeles basin would not have been suitable for settlement, especially low-lying Long Beach where the Los Angeles river empties. The same goes for Venice Beach/Marina Del Rey where the Ballona Creek empties. Thus dry land with large trees and easy access to a major river was a prime place for a homestead. After the discovery of gold, California wealth began to obviously grow, and more people moved to Los Angeles partly due to this. Then when oil was discovered in Southern California in the late 1800s, much more wealth followed. All these people needed somewhere to live, and where better than the thriving and already popular downtown. All that wealth necessitated banks and other financial institutions. People led to businesses, which led to more people. Thus is the the history of downtown. However, in the grand scheme of things, it really doesn't bare much importance today where the \"downtown\" of Los Angeles is located. The entirety of Los Angeles county, Orange County, and much of Ventura, Riverside, and the population center of San Bernardino County are all integral organs of the fully-functioning whole of \"Los Angeles.\" Downtown Los Angeles is hardly a centralized business sector in the way that Manhattan is to New York, upper New Jersey and southwestern Connecticut. This may be in part due to some of the key elements for a major city which Los Angeles is lacking, and you have pointed out a couple of these. Instead, Century City, Beverly Hills, West Hollywood, Santa Monica, Long Beach, Burbank, Glendale and Irvine, just to name a few, are not part of the city of Los Angeles, and all have thriving economies, tall buildings, and could be considered legitimate downtowns of their own right."
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28d9mi | If a large astroid is on path to hit earth, would we be able to do anything about it? | askscience | http://www.reddit.com/r/askscience/comments/28d9mi/if_a_large_astroid_is_on_path_to_hit_earth_would/ | {
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"The answer to this depends on a great number of factors, such as how much advanced notice do we have, what is the mass and velocity of the asteroid, what what material is the asteroid composed, etc. Get enough of an advanced notice and we could conceivably nudge it off course. NASA is even talking about [catching one of the smaller ones](_URL_0_).",
"maybe.\n\nIf we had enough time we could do several things.\n\nif it was a comet (made largely of ice) We could shine a laser at it, causing it to out gas on one side potentially moving it off course.\n\nwe could attach a small rocket/ion engine to it and push it off course\n\nwe could park a small space craft in front of it and use the gravity of the space craft to pull it off course.\n\nWe probably WOULDN'T try to blow it up, as this would cause many dangerously unpredictable chunks. And many of the bigger asteroids would require many many nukes to blow up, if we could at all. However if the comet, or asteroid was small enough, and comprised of the right material blowing it up might make the chunks small enough to burn up in the atmosphere.\n\nAll of this assumes we discover it years or many months in advance. ",
"Short answer, almost definitely nothing. There's \na lot of ideas, but nothing other than theorizing has \n been done to build *and test* a defense. \nTesting is the hard part, and a lot will be required before\nWe can have confidence in any defense system.",
"Plenty, the issue is catching them in time. With time, we actually have the resources and expertise to prevent any damage.\n\n[Ed Lu - Thwarting Dangerous Asteroids Begins with Finding Them](_URL_0_)\n\n[B612 Foundation](_URL_1_)\n",
"It may seem odd to use a space probe the size of a washing machine to fend off an asteroid that weighs in at a couple of hundred tons, but then, a few ounces of lead are enough to bring down an elephant. It’s a matter of putting enough energy behind the bullet. In this case, the bullet is a spacecraft, but even moving at orbital velocity the effect wouldn’t do much to an asteroid large enough to pose a danger to Earth. However, it doesn’t have to, if the impact is properly timed.There are hundreds of near-Earth asteroids hurtling through space that are a potential danger to our planet. One way of dealing with the problem is todeflect them with a space probe deliberately set on a collision course. To see how effective such a collision would be, Frank Schäfer of the Fraunhofer Institute for High-Speed Dynamics, Ernst-Mach-Institut, EMI in Freiburg, Germany is looking at what asteroids are made of and how this affects a deflection impact.\n“In actual fact, the impact of a space probe would change the speed of the asteroid by just a few centimeters per second. But that’s enough to deflect its course to a significant degree over a longer period. So if we want to stop an asteroid on collision course with the Earth from hitting us, we’ll need to fire at it many years ahead of time,” says Schäfer.\nThe study originally wanted to look at how to deflect asteroids between 100 and 300 m (330 and 990 ft) in diameter by striking them with massive space probes in a manner that was described as similar to two balls colliding in billiards. However, Schafer noticed that something else was going on, other than simple recoil. The substance that the asteroid was made of was also a factor, especially if the impact threw off a plume of debris. In this case, the momentum transfer is up to four times greater than a simple impact.\n“During impact, not only does the probe transfer its own momentum to the asteroid, there is also the recoil of detached material from the crater, which is ejected against the direction of the impact,” Schäfer says. “This recoil effect acts like a turbocharger on the deviation of the asteroid.”\nSchäfer’s experiments involved taking pendulums and attaching materials similar in consistency to those that make up asteroids, such as dense quartzite, porous sandstone or airy concrete. He fired aluminum projectiles at them at up to 10 km/s (6.2 miles per second) while recording the results with high-speed cameras, interferometers and lasers.\nThe results of the experiments demonstrated that the asteroid’s substance affects the outcome of a probe impact. A porous substance will absorb the strike, similar to how the crumple zone of a car soaks up the energy of a crash. Conversely, a denser, more elastic substance will enhance the deflection.\nPart of the NEOShield program, Schäfer’s work will be used by the project in its plans to try deflecting an asteroid by mid-2015."
]
} | [] | [] | [
[
"http://www.nasa.gov/mission_pages/asteroids/initiative/#.U6BNVvlSY5Q"
],
[],
[],
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"http://longnow.org/seminars/02013/jun/18/anthropocene-astronomy-thwarting-dangerous-asteroids-begins-finding-them/",
"https://b612foundation.org/"
],
[]
] |
||
4thoih | what sense is most 'awake' when asleep? | I find that light wakes me up the most, but some people say they wake up to sounds/touch much faster. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/4thoih/eli5_what_sense_is_most_awake_when_asleep/ | {
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"with sound, I think it depends on if you have background noise on. Like I used to sleep with a radio on growing up, wasn't very loud but because of that, I wouldn't really wake up to other outside noises. Now I sleep with nothing on and I feel like I can wake up easier if a noise occurs"
]
} | [] | [] | [
[]
] |
|
3m4feh | how the time scale of minutes, hours, 12 hour half days, and 24 hours in a day were chosen. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/3m4feh/eli5how_the_time_scale_of_minutes_hours_12_hour/ | {
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"Our system of time is based on 12. 12 can be divided by 2,3,4,6, and 60 can be divided by 2,3,4,5,6,10,12, ect. For normal every day use its extremely useful to be able to break time into those segments, and there are lots of even cuts that can be made.\n\nThere are other systems, however. Submarines use 18 hour days (6 sub hours is 8 normal hours), but I'm not sure why.",
"Notice they are all base 6? Just like 360 degrees in a circle. This is because the first ones to write about it (Sumerians) had base six number system. \n\n_URL_0_"
]
} | [] | [] | [
[],
[
"https://en.wikipedia.org/wiki/Sexagesimal"
]
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||
a0qk81 | What is the black-body radiation of a negative-temperature body? | That is to say, an emitting medium in a population inversion? Are higher frequencies more common than low? | askscience | https://www.reddit.com/r/askscience/comments/a0qk81/what_is_the_blackbody_radiation_of_a/ | {
"a_id": [
"eajqv66"
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"score": [
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"text": [
"Population inversion can't exist at thermal equilibrium, so you can't really expect the system to radiate according to the Planck distribution, which describes the radiation emitted by a system at thermal equilibrium.\n\nPopulation inversion is used in lasers, which certainly don't emit a thermal spectrum. You can read more about that [here](_URL_0_)."
]
} | [] | [] | [
[
"https://en.wikipedia.org/wiki/Population_inversion"
]
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|
327k7f | what's the difference between simulator and emulator? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/327k7f/eli5_whats_the_difference_between_simulator_and/ | {
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"A simulation is a system that behaves similar to something else, but is implemented in an entirely different way. It provides the basic behavior of a system but may not necessarily abide by all of the rules of the system being simulated. It is there to give you an idea about how something works.\n\nThink of a flight simulator as an example. It looks and feels like you are flying an airplane, but you are completely disconnected from the reality of flying the plane, and you can bend or break those rules as you see fit. E.g.; Fly an Airbus A380 upside down between London and Sydney without breaking it.\n\nAn emulation is a system that behaves exactly like something else, and abides by all of the rules of the system being emulated. It is effectively a complete replication of another system, right down to being binary compatible with the emulated system's inputs and outputs, but operating in a different environment to the environment of the original emulated system. The rules are fixed, and cannot be changed or the system fails.\n\nCredit: _URL_0_\n\n",
"A simulator makes the user feel like they're in a specific environment.\nAn emulator makes the game work like its in a specific environment.",
"As others have said, but simplified, \n\nSimulators simulate real world things. Example. I can have a driving simulator, rain fall simulator, etc. \n\nEmulators are things that pretend to be other things to get something to work. Example. I have a Pokemon game for my gameboy. I download an emulator on my phone, and can run the game file because my phones pretending to be a gameboy. (A simulation example of this would be I ran a simulation to see my chances of beating this Pokemon \"--\")"
]
} | [] | [] | [
[
"http://programmers.stackexchange.com/questions/134746/whats-the-difference-between-simulation-and-emulation"
],
[],
[]
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||
3od6q5 | If you are in space and objects accelerate past you, will you feel force? | askscience | https://www.reddit.com/r/askscience/comments/3od6q5/if_you_are_in_space_and_objects_accelerate_past/ | {
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"Ok, so I'm not any sort of scienceologist, but I'm pretty confident that the answer is \"no\". There is no shared medium in space that would transfer any compression wave to you. The only way you would experience a force would be if you ended up in the path of whatever emissions this object may be releasing."
]
} | [] | [] | [
[]
] |
||
3xhedc | why do people say an atheist can't be a republican? | I'm a republican on most political issues, I lean to the right on almost everything. Except that I lean to the left on things like gay rights, religion, and social issues. When I tell people that I am an atheist and identify as a republican they tell me that I can't be both. Am I just using the wrong terminology? Should I say I'm a right leaning democrat? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/3xhedc/eli5_why_do_people_say_an_atheist_cant_be_a/ | {
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"I like to call that a 'sensible republican'... \n\nMy girlfriend is like that... fiscally conservative and socially liberal.",
"They are incorrect, either as a joke or just being fairly misinformed.\n\nCurrently strong evangelical christians make up a very vocal part of the republican party. Also, republican talking heads will frequently bring up things like \"the war on christmas\" to get ratings. However, it is just ognorant to presume all christians are republican or all republicans are christians.\n\n\n\n",
"Virtually every republican candidate at the moment has used rhetoric which heavily favors Christian religions, going so far as to imply that they're basing their decision on religious values.\n\nYou may want free market capitalism but consider yourself a \"liberal\" on some issues--which is to say, you're probably a brogressive or lifestylist--but the Republican candidates at the moment are all heavily *not* \"left-leaning\" on a lot of issues, and given that they also seem to hold God as an actual, viable authority for governmental decision making, it's just *really really* strange that you're an atheist and somewhat socially progressive and still supporting the current Republican party.\n\nIt's probably meant as a joke, and I've never heard anyone say that, but it is really rather odd.",
"There are more than two political parties. If you identify with Republicans on fiscal issues and Democrats on social issues, then you more than likely are some type of Libertarian (or even independent).\n\n_URL_0_\n\nEdit: a word",
"I think that you have further misunderstandings. While there are likely more atheists on the left, Dem politicians have to pay the same sorry lip service to Yahweh that Repubs do. On the right, there is just more nonsense about other religions, Christmas, and abortion.",
"Polarization.\n\nOnce someone affiliates themselves with a party, we see this trend where they have a negative opinion of the other party. None of it has to be based in truth (much of it is not) but this division between people is reffered to as polarization.\n\nIf you are a polarized individial often instead of considering any argument presented, you are convinced the opinion is wrong. So, these people that are polarized democrats associate atheism with democrats and therefore it *cannot* be within the realm of the opposit party.\n\nWhich is alot like saying, Democrats love Cheerios, so obviously republicans can't also like Cheerios.\n\nTLDR: stupid people assume that a political division can easily sum up views when a political affiliation is much more akin to likeing a sports team. I can't assume that because you are a packers fan you love cheese ^but ^if ^you ^dont ^like ^^cheese ^^you ^^have ^^no ^^^soul. "
]
} | [] | [] | [
[],
[],
[],
[
"https://reason.com/poll/2014/07/10/53-of-millennials-would-vote-for-a-socia"
],
[],
[]
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|
1ynro9 | Has anyone here read Wendy Doniger's "The Hindus: An Alternative History" and can tell me why it's controversial enough to be censored? What do academic historians think of the book's contents (regardless of their thoughts on censorship)? | So I heard that this book was banned (or ceased publication due to pressure) in India.
I assume most historians would be for free speech and discourse, so I'm not asking about the ban itself. Is the history presented in the book legit? What exactly in the book pissed people off? | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/1ynro9/has_anyone_here_read_wendy_donigers_the_hindus_an/ | {
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"Hindusim, as it's practiced today–as with much we think of \"traditional\" in India—was heavily influenced by British colonialism, both in terms of what the British thought it was and should be, and as a reaction of Indian intellectuals to what the British thought about it. Doniger points out the big, messy, and diverse nature of Hindusim. This contradicts modern orthodoxy."
]
} | [] | [] | [
[]
] |
|
2m8tfl | What happens if an earth-like planet crashes into a star? Or at least fall out of orbit and start approaching it? | Inspired by this post: _URL_0_ | askscience | http://www.reddit.com/r/askscience/comments/2m8tfl/what_happens_if_an_earthlike_planet_crashes_into/ | {
"a_id": [
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"text": [
"An Earth-like planet crashing into its star is less like a crash than it is like a gnat flying into a campfire. The planet would vaporize as it falls into the deeper layers of star."
]
} | [] | [
"http://www.universetoday.com/113488/how-do-gravitational-slingshots-work/"
] | [
[]
] |
|
yb635 | how do i choose a credit card? | Every advertisement I'm sent always make their information sound great, but I have no idea how to read the fine print, nor do I really know what they're bragging about.
How can I tell what's a good deal?
What do all the terms mean?
What are average numbers for those terms?
What benefits would I have from getting a credit card or not? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/yb635/eli5_how_do_i_choose_a_credit_card/ | {
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"c5u1lae"
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"text": [
"It depends - the credit card issuers put different features on different cards so that they'll appeal to different people.\n\n - Some credit cards are low fee. Get one of these if you want to be frugal.\n\n - Some cards are low interest. Get one of these if you have lots of high interest debt that you want to consolidate and pay down.\n\n - Some cards have fancy rewards. Get one of these if you can use the rewards, or if you like trying to game the system.\n\n - Some are an unusual colour or design to indicate that you have lots of money, so you can impress your friends.\n\nBecause of these factors, it's not possible to objectively compare all credit cards and identify the \"best\" one. You need to figure out for yourself what is important to you and whether you want any specific features. If you're not sure, I'd suggest sticking to a low fee, low frills card for now.\n\nIn addition to the features above, having a credit card can help you build up a credit history, it can help with monthly budgeting, and you can avoid carrying cash."
]
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[]
] |
|
1ethv8 | if the majority of the world's human and plant population was wiped out suddenly, how would the survivors access the seed banks? | In particular, the Svalbard Global Seed Vault in Norway. It seems to be under a lot of physical protection that an average person would not be able to get through. How would the survivors get access to the important seeds in order to restore essential plant life? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1ethv8/eli5_if_the_majority_of_the_worlds_human_and/ | {
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"text": [
"You're assuming that the staff that tend to the seed bank are also wiped out suddenly, and the seed bank survive intact.\n\nI'd find it hard to imagine a scenario where that would be true.. I'd imagine that it's manned 24/7.. If the seed bank survives, the staff manning it will be ok too...\n\nNot to mention the Norwegian Government forseeing impending doom (e.g. we could have a few days forcast of a meteor strike that wold severly affect the worlds population), so they stick a few more experts in the safe zone to help the world get back up on its feet...\n\nI really wouldn't worry about this sort of thing!"
]
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[]
] |
|
1l3ply | If a multilingual person suffers from aphasia could they loose comprehension of one language while retaining the ability to understand another? | I was curious seeing how certain types of aphasia can be selective. | askscience | http://www.reddit.com/r/askscience/comments/1l3ply/if_a_multilingual_person_suffers_from_aphasia/ | {
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"what kind of aphasia?",
"Interestingly, this is very important for epilepsy surgery and brain mapping. Often when planning a resection for a neurosurgical procedure, [stimulation mapping](_URL_0_) will be used to identify important areas to avoid. Through this technique, it has been shown that different languages are stored in slightly different regions of the brain.\n\nYoumans Neurological Surgery says: \n\n > It has been shown that if another language is acquired as a second language, more diffuse localization is seen than with the primary language (Haglund and Ojemann, unpublished observations). It has also been shown in sign language patients that localization of American sign language differs slightly from that of naming in hearing patients proficient in sign language. \n\nYou may be able to find more information on ASL [here](_URL_1_)."
]
} | [] | [] | [
[],
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"http://en.wikipedia.org/wiki/Cortical_stimulation_mapping",
"http://www.sciencedirect.com/science/article/pii/S0093934X83710023"
]
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|
4o1isu | why is our writing voice often so different from our way of speaking? | [deleted] | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/4o1isu/eli5why_is_our_writing_voice_often_so_different/ | {
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"Basically, it's much easier to go over your writing and make changes until you like the way it sounds than it is just think about your words and get them all out in one try.",
"Your observation is not true for everyone. I'm a writer, professionally and temperamentally, and one of the best pieces of advice I've ever read/heard for those in the profession is to write like you speak. It's stayed with me over the years.",
"You rely a lot more on understood meanings/contexts and gestures and tend to be more repetitive when you speak for one. When you write, you have to clarify the context because you don't know who will be reading your writing or where they will do it. Similarly, you can't use gestures for obvious reasons so your words have to make the meaning clear all on their own. And you don't repeat as much since the reader can always re-read.\n\nDepositions show this pretty well. In a deposition, a court reporter types down exactly what everyone says. It's really weird to read one and see how you talk written down exactly. Part of the weirdness comes from the fact that one person is interrogating another, but general speech patterns vs. writing patterns show through too."
]
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2sfk0e | how come my vitamin c tablets have 1250% of the recommended daily allowance of vitamin c? | Seems like overkill... | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/2sfk0e/eli5_how_come_my_vitamin_c_tablets_have_1250_of/ | {
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"Some people require more vitamin C than others because the have a condition or was previously deprived of it. \n\nNote: if you're taking those tablets for a flu or a cold, unless you're deprived of vit. C or have some sort of condition, extra vitamin C doesnt work. It gets flushed out of your system since it isn't needed.",
"A couple reasons. First, a lot is wasted and isn't actually utilized in the body. Acids or other microbes can use it up too, so you don't get the full about found in a pill. They overload your body with it so your body gets 100% (or at least close) of the vitamins suggested daily.\n\nSecond, your body can't utilize so much if it doesn't need it. So again they overload your system, so as the vitamins pass in your intestines and uses up those vitamins normally, there's an excess to refill what your body uses throughout the day.",
"Government recommendations around the world for daily Vitamin C intake range between 40-100 milligrams per day.\nThat is just the minimum of what is needed essentially so you don't suffer ill effects such as scurvy. However many supplement advocates suggest much higher doses have beneficial health effects, so if it has 1000 mg than obviously its gonna be a huge percentage higher than the official RDA/RDI.\n\n",
"Notwithstanding rare medical conditions that require high vitamin doses, it's because consumers generally have a very weak understanding of biology/nutrition and end up taking a simplistic \"if some is good, MOAR IS BETTER!\" view. Vitamin companies know this, and are happy to take advantage.",
"Vitamin C is incredibly water soluble and completely harmless in anything less than absurd (like 50-100+ grams) amounts, so any marginal health benefits from taking 10x+ the recommended daily value grams a day (especially when sick) are totally worth the risk. also that recommended daily value is pretty close to a minimum just to prevent scurvey, with vitamin C more is always better",
"What everyone is saying is true, there is also no regulation on vitamins. So companies that are making and selling them have no real rules to follow. Unless a doctor has told you that you are lacking a certain type of vitamin or mineral, it can actually be bad for you to take daily vitamins.",
"Jack and Bob don't know much about Vitamins other than that they're good for you. If some Vitamin is good for you, says Jack, then more must be better! Jack turns his nose up at Bob's vitamin which only has 100% of a day's supply.\n\nJack buys the product that he thinks is better, even though it has no more benefit than Bob's product. \n\nTL; DR consumers think it'll get them a benefit, so there is incentive for the company to target these consumers. There is not a benefit for most people."
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92ajgz | why a lot of email scams actually look like scams? i have noticed many of the junk mails i receive, utilize random capital letters, bold writing, excessive exclamation marks and poor grammar. what do they hope to achieve from this any why do they not put more effort into their scam advertising? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/92ajgz/eli5_why_a_lot_of_email_scams_actually_look_like/ | {
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"Scammers will commonly use poor grammar, awkward phrasing and spelling on purpose as a sort of filter. Anyone responding to those emails must not be aware of the scam and or must not be smart enough to realize it is before it’s too late. It’s a fishing method that gets all the VERRY susceptible people.",
"Most scam mails involve some kind of interaction with the victim before any real money is exchanged. So you have to keep in mind that the scammers themselves are also making a time investment.\n\nSuppose you are a scammer and you craft a really good and legit looking opening email. You receive 10000 replies from people who think it's real. But almost no one just instantly transfers large amounts of cash to some random guy based on one email, so now you have to respond to 10000 mails with your fake credentials, more details on how they have to pay, etc. \n\nThen you suggest some of those really shady bank transfers, or something weird like paying by using \"STEAM cards\" (yes, that's a thing) because you can't use legitimate methods for the transfer, or else it could be used to track you, or maybe undo the transfer, etc. Or they could be asking friends or even lawyers for advice, who then tell them it's probably a scam. So before they end up paying, most rational people will realize it's a scam, and you wrote all those 10000 reply mails for nothing.\n\nBut now suppose you make a reaaaaally bad first mail. The kind of thing where almost anyone will laugh it off and go on about their day. Maybe this time, you only get 10 replies, but those 10 replies are orders of magnitude more likely to actually go through with the exchange, because if they hadn't noticed how bad the first email was, then they are also a lot less likely to notice other inconsistencies. So now you can devote your time to those 10 replies instead of having to manage 10000 contacts with people of which 99.99% won't send you their money anyway."
]
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||
23h0td | Movies and Television series often portray certain swordsmen as "heroes" or "experts." People whose skill in battle far exceeded all of their opponents. Were there actually such swordsmen or warriors in the middle ages who had such unmatched skill or prowess? | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/23h0td/movies_and_television_series_often_portray/ | {
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"The only one who comes to mind right now is *Miyamoto Musashi*, a Japanese swordsman who lived in the late 1500s and the first half of the 1600s. He was a soldier at the Battle of Sekigahara among others, but he also fought a great number of duels and was allegedly never defeated. ",
"These kinds of larger-than-life heroes are everywhere in medieval literature. You see them in Beowulf and other Anglo-Saxon epic poetry (like the Battle of Maldon), Gregory of Tours, the Icelandic Sagas, Arthurian romance, etc. Super-human heroes were as much a part of the medieval imagination as they are of our own re-imagining of the middle ages. So whether or not real people actually managed to live up to these heroic ideals, being the kind of badass who could hold off an army single-handed was definitely something to which real warriors aspired throughout the medieval period.\n\nFiguring out if real people managed to reach this level of badassery is more difficult, because the lines between factual reporting and literary embellishment that matter so much in modern journalistic writing weren't as much of a priority in the middle ages. So while we have many historical accounts of people heroically and single-handedly fighting off multiple opponents, it's hard to tell if this is a real thing that happened, or the author remembering real events through the lens of tropes taken from epic literature and fiction.\n\nBut fiction and real life are always mutually structuring (fiction mirrors real life, and people model their actions on fictional ideals), so it's pretty safe to say that real people *did* sometimes pull off the kinds of heroic deeds that litter medieval literature (and that modern fantasy authors have taken up and worked into their stories)."
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3ptke2 | How do U.S. servicemen who married Asian women between 1942-1967 get around anti-miscegenation laws when they returned to the states with their brides? | [deleted] | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/3ptke2/how_do_us_servicemen_who_married_asian_women/ | {
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"The law on the books for Virginia for instance, did not speak at all too the Asian population, but ONLY to marriage between black and white. \n\nThat was actually appoint during the Supreme Court's hearing of Loving v. Virginia, where because the law only spoke about 2 races, it was clearly racially biased and thus violated the Equal Protection clause. The argument for Virginia was that because a Legislature is not psychic and there were so few Asians in the state at the time of the writing of the law they should not have had to contend with that set of circumstances, and that since both white and non white were punished equally it was not biased the Court took a dim view of that argument. "
]
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[]
] |
|
k5yyh | Is it possible to make an entirely frictionless surface? | And if that's impossible what's the closest we can get? | askscience | http://www.reddit.com/r/askscience/comments/k5yyh/is_it_possible_to_make_an_entirely_frictionless/ | {
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"text": [
"As far as I know, it is impossible to create a truly frictionless surface, but we can come very close. See: [Superlubricity](_URL_0_)",
"As far as I know, it is impossible to create a truly frictionless surface, but we can come very close. See: [Superlubricity](_URL_0_)"
]
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"http://en.wikipedia.org/wiki/Superlubricity"
],
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]
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|
7mnbp1 | Are modern day cinematic representation of WWII infantry helmets accurate in terms of durability? | For example, in movies and shows like saving private Ryan and band of brothers, sodlers are quite often shown taking a bullet to the helmet and the bullet going through with little to no trouble. It almost seems like helmets were basically pointless when it came to a direct hit. Was that accurate from back then? Whether it be due to technological/design limitations or did we just not have a good enough understanding of ballistics to make a helmet that would stop most infantry rounds? Were they meant to just protect from shrapnel or other chunks of debris but not whole bullets? Are these movies and TV shows just inaccurate? (I would understand your every day war movie, but SPR and BoB are known for they're fairly impressive historical accuracy)
I apologize if this has been asked before. I'm on mobile and can't really search effectively. Feel free to remove if need be. | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/7mnbp1/are_modern_day_cinematic_representation_of_wwii/ | {
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"There are enough leftover WWII helmets still around (as the design and materials didn't significantly change for decades) that the ones in the films are quite likely vintage. They were designed to deflect shrapnel and debris, and deflect rounds that weren't full-on, but they couldn't stop them. But remember, most of the stuff flying in wartime is not aimed directly at any one person. There are a lot more shrapnel, rocks thrown up by explosions or shooting, suppressive fire, and badly-aimed rounds than there are sniper bullets. Sometimes, even fairly direct hits could be deflected because of bullet tumble or other accidents of physics.\n\nMore importantly, even most modern Kevlar military helmets won't stop a direct round in most cases. When I was in Iraq, one of the guys in my unit was shot almost point-blank with a 9mm pistol. It entered the Kevlar of his helmet, and the layers did deflect it upward and out, so it didn't actually touch him - but it didn't just bounce off, either; the helmet was toast. If he'd been shot with, say, a 7.62 round, it would likely have punched through. How much damage it would do after that would depend on the range it was fired at; close up, it might still kill, but from further away it might just give you a bruise and get stuck between helmet and head. The new ECH will apparently stop a 7.62 round, but this was big news in 2013.\n\nThe old helmets just weren't capable; you'd have to have so much steel they'd become functionally useless. We only achieved this level of protection with Kevlar and similar materials. The tradeoff is, of course, that the steel pots were used for cooking, heating water for shaving, and other things; the new Kevlar ones have only one use.\n"
]
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4q3794 | What effects does a pear-shaped nucleus actually have on an atom? And what causes it? | I just saw [this post](_URL_0_) in /r/science which talks about a pear-shaped nucleus. There was an article linked, but it was a bit above my understanding.
So given that I was always told that an atom's nucleus is spherical, what do different shapes mean? | askscience | https://www.reddit.com/r/askscience/comments/4q3794/what_effects_does_a_pearshaped_nucleus_actually/ | {
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"Just going to add that the paper can be found on arxiv: [Direct Evidence of Octupole Deformation in Neutron-Rich ^(144)Ba](_URL_0_)",
"I'll try and make this as simple as possible.\n\nNuclear structure is something that's poorly understood. Specifically, when I say nuclear structure, I mean the way the protons and neutrons assemble, such as the shapes of their wavefunctions and their energies. Protons and neutrons in a nucleus are a lot like electrons in an atom - they have specific wave functions for each energy state, and they progressively fill higher and higher energy states. This is what we call the 'nuclear shell model.' \n\nWe've got good measurements for lots of the ~250 stable nuclides, but there are *thousands* of unstable nuclides, such as ^(144)Ba. We need measurements of *those* nuclides if we're ever going to be able to build good nuclear models. The 'octopole deformation' (and its magnitude) tells us something about the collective behavior of nucleons, especially for something that's very neutron rich like ^(144)Ba.\n\nIt's a good thing to know if you want to model nuclear energy levels - generally it's hard to get information like this for unstable nuclides, especially ones so far from stability. It's been well established for a while that octopole deformations exist, but to the extent of my reading of the paper this is the first time they've gotten a measurement of the formation for this specific nuclide. It's a useful and important piece of information. They did good work. \n\nUltimately, the more we know about the structure of neutron rich nuclei, the more we can understand about their energy levels and decay properties, and so the more we can understand nucleosynthesis in neutron rich environments and fission physics. ",
"Since you seem to be also asking about shapes in general, the deformed liquid drop model is a good starting point.\n\nAssume the nucleus is a drop of incompressible liquid. A water drop wants to be spherical, in order to minimize surface tension. But assume that positive charges are distributed uniformly throughout the fluid, like protons in the nucleus. The protons repel each other. But the protons must remain evenly spaced, and the liquid cannot expand or contract. all that's left is for the drop to deform. In this case, a spherical shape is an unstable equilibrium. Give it a tiny tiny push and it will deform and elongate, like a football. \n\nOf course none of these assumptions are really correct, but I find it illustrative."
]
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1z3ofw | why can i roll my eyes toward the top of my head but not the bottom? | explainlikeimfive | http://www.reddit.com/r/explainlikeimfive/comments/1z3ofw/eli5_why_can_i_roll_my_eyes_toward_the_top_of_my/ | {
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"I can't understand the question fully, care to elaborate OP?",
"Your optical nerve attaches to the back of your eyeball at an upward angle just below your eyes midpoint. As you look down, it causes more tension as it tries to straiten the optical nerve, as opposed to when you look up, the tension is released on the nerve by laying it flat against the bottom of your eye socket. \n\nThink of it like when you stretch a rope at an angle (like a slide), with a high point and a low point. Now take the high point and try to raise it whilst keeping the same point on a horizontal axis (looking down). You cant. Because the rope will want to try to reduce its angle on a vertical axis. Now take the rope's high point and lower it, whilst keeping the same point on a horizontal axis (looking up). Its much easier. Because as the high point lowers, it gives the rope more slack, just like the optical nerve when you look up. \n\n"
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9zng8p | how is it physically possible, across all species, for hummingbirds to flap their wings anywhere from 10-30 or in the extreme up to 70-80 times "per second", or is that unit misinterpreted? | I can't seem to find a specific answer for this in regards to *how*. It just seems so odd. My lack of understanding is taking this unit as basically saying time is slowed down for Hummingbirds. I cannot wrap my head around how this makes any sense. | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/9zng8p/eli5_how_is_it_physically_possible_across_all/ | {
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"Hummingbirds have tiny little wings and relatively strong muscles to move those tiny little wings.",
"The balance between weight and power. Dragonflies and other insects also flap their wings incredibly fast. It's only possible with relatively small surfaces and a very specific shape/function of the wing.\n\nSo speaking of physics, it's not that special. The biology is much more interesting, in the crazy amount of energy they need. More info here: _URL_0_\n\nThree relevant ones:\n\n* They're the smallest bird.\n* They eat a lot\n* They go into torpor (an almost coma-like state)",
"The vast majority of people (barring some sort of pathology) don't have to think about all the tiny muscle movements that keep you upright while standing, walking, and running, I imagine a hummingbird isn't consciously flapping its wings like that either, it just knows it wants to fly to that flower and autonomic motor control takes care of the rest.",
"A human blink lasts about a tenth of a second. So, 10 a second. When your eyes jump around a page with a saccade, that can be as brief as 20ms. You probably couldn’t achieve a stretch of 50 of those in a second, but that’s the sort of speed we’re talking about. "
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348z9v | "Hitler lost the war the moment it began"; Is there any truth to this? | I remember hearing this somewhere when i was in high school, but can only recall them saying it was because of the training of massive numbers of paratroopers somewhere (im assuming Soviet), and how they had many more weapons being made every day. | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/348z9v/hitler_lost_the_war_the_moment_it_began_is_there/ | {
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"This is most likely a reference to the economic realities of Nazi Germany and their inability to fight a long, sustained war against the Allies. There are several older threads discussing the economics question in detail:\n\n[How did Germany fund their rise out of the depression following WWI, let alone an army to fight in WWII?](_URL_2_)\n\n[What was Nazi Germany's economy like before WW2? Were they prepared/preparing for a large war?](_URL_0_)\n\n[To what extent was Nazi Germany's economic development form 1933 onward \"unsustainable\"? And what effect did it have, if any, on their decision to go to war when they did?](_URL_4_)\n\n[How stable was the Nazi economy? Would it have collapsed without war as some claim?](_URL_3_)\n\n[Where/how did Nazi Germany get access to enough oil to fuel the war?](_URL_1_)",
"The Soviets were indeed the first to utilize the concept of paratroopers, however most of their operations were limited with the majority of their paratroopers being used as regular infantry. That being said.... It depends on what angle one approaches this from, as this is one of those questions that never gets a straight answer, because even though it deserves one, it can't have one. Lets approach this from the view of validating your question. When Hitler went to war in 1939, he (as has been generally accepted) did not imagine the British and French would declare war for the poles (consider that Poland as a country existed for under 20 years at that point.) Even though the British and French did have obligations to defend Poland in the event of war, Hitler did not believe they would (Munich, Anschluss and the blatant violation of Versailles had shown them as weak.) One can argue that without the Soviet Union, it would have been a monumental task (it still was) to defeat Germany. At the start of the war, Hitler had signed a non aggression pact with the USSR, which would have kept Stalin out of a war he knew he wasn't ready to fight (its arguable that the USSR would not be ready for war until the mid 1940s.) Now that we have set the conditions as they existed in 1939, no the war was not lost the moment it began and until 1941, the world would have disagreed with this statement and here is why; the Germans had defeated the French (who had what most consider the best army in Europe at that point) and had the British with their backs against the wall with u-boats sinking British merchant vessels at an alarming rate. If you want to point to a single event that certainly ensured the defeat of Nazi Germany, you have two. The first being June 22nd 1941, which is when the Germans invade the USSR and December 11th 1941 when Hitler declares war on the United States. Those are two concrete days that certainly ENSURED Hitler would lose the war. ",
"In his massive tome *A World at Arms*, the historian Gerhard Weinberg noted that after reading the memoirs of German generals. there was a common refrain of \"if only the Führer had listened to me...\" Weinberg sarcastically quipped that these memoirists should have added \"the war would have lasted another six months, and then the Americans would have dropped an atomic bomb on Berlin.\" \n\nBearing aside the issues of the actual decisiveness of the nuclear weapons and whether or not the US could have brought them to bear on Germany, Weinberg's sarcastic comment has a lot of truth to it. The odds against a German victory were quite long and grew immeasurably shorter when the US entered the war. Germany simply lacked the resources to crush its opponents in the material-intensive war it found itself fighting. Barbarossa is a case in point. Germany invaded the Soviet Union in ideal conditions: it had achieved strategic surprise, the Red Army was out of position and still suffering the after-effects of the Purges, Germany quickly established air superiority, and the German armies possessed an operational cohesiveness from earlier campaigns. Despite winning truly massive victories in the various cauldron battles in 1941, the German armies could never completely destroy Soviet fighting power. German armies soon found themselves at the end of an increasingly strained logistical system facing a still-intact Red Army. Although German operational effectiveness meant Germany retained a degree of initiative in 1942, Soviet production numbers had began to outstrip German production in war material. In short, Germany could not win this war despite its impressive early victories. \n\nThe best sources for the macro-picture are Richard Overy's *Why the Allies Won*, Williamson Murray and Allen Millett's *A War to Be Won* and Adam Tooze's *Wages of Destruction* for the specific shortcomings of the German wartime economy. "
]
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"http://www.reddit.com/r/AskHistorians/comments/1eck8t/what_was_nazi_germanys_economy_like_before_ww2/",
"http://www.reddit.com/r/AskHistorians/comments/1b66lm/wherehow_did_nazi_germany_get_access_to_enough/",
"http://www.reddit.com/r/AskHistorians/comments/1t2n6m/how_did_germany_fund_their_rise_out_of_the/",
"http://www.reddit.com/r/AskHistorians/comments/14kinc/how_stable_was_the_nazi_economy_would_it_have/",
"http://www.reddit.com/r/AskHistorians/comments/1e0hmf/to_what_extent_was_nazi_germanys_economic/"
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6o2f0h | why/how did venezuela develop a coin shortage a few years ago? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/6o2f0h/eli5_whyhow_did_venezuela_develop_a_coin_shortage/ | {
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"At one point the value of the metal in the coins was worth more than the coins themselves due to inflation. When this happened any coins people had were melted down and paper money had to be used."
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3f7gni | Is there a limit to how fast a substance can go through a pipe/tube? | The pipe or tube is indestructible and does not get wider with an increase in pressure. I'm not sure if the substance matters, but if it does lets say either water or oxygen is being forced through.
Is there a theoretical limit at which you cant force a substance to travel faster through a fixed pipe? | askscience | http://www.reddit.com/r/askscience/comments/3f7gni/is_there_a_limit_to_how_fast_a_substance_can_go/ | {
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"Is the pipe frictionless,and does the fluid/gas have viscosity?\n\nMost real pipes have a boundary layer close to the edges.\n\nOther than those two issues,the limits would be how hard you can push (it's going to require more force the faster you go),and eventually,the speed of light.\n\nYou might also need to worry about phases changes(under enough pressure it'll turn solid),if you pushed hard enough"
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65q3qi | how close can we get a bomb to be as strong as a nuclear bomb without having it being nuclear? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/65q3qi/eli5_how_close_can_we_get_a_bomb_to_be_as_strong/ | {
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"There's an upper limit on the energy density of explosives, particularly on a mass basis. An airplane has to be able to lift, carry, and drop the thing.\n\nFor comparison, the Little Boy bomb that the US dropped on Hiroshima in WW2 was well over 1000 times more powerful than the MOAB the US dropped in Afghanistan, while also being about half the weight (and at a time where nuclear weapons were very inefficient)."
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6p47v1 | Did Tolkien use a lot of his experiences in WW1 to inspire certain parts of Lord of the Rings? | After learning a lot about WW1 and watching Lord of the Rings I can't help but feel he based a lot of parts in his book on his experiences in the war. ie. The idea of adventure and the unknown of Sam and Frodo heading out of The Shire, Saroman's age of industry trying to conquer all, a war to end all wars and shower the world in darkenss, and the needless death and destruction verses the unyielding hope of Aragorn and Gandalf. Even Smeagals schizophrenia is like a soldier with PTSD! thanks in advance for reading. | AskHistorians | https://www.reddit.com/r/AskHistorians/comments/6p47v1/did_tolkien_use_a_lot_of_his_experiences_in_ww1/ | {
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"Tolkien was annoyed by analysts who claimed his work was an allegory of WW2, and responded that firstly he did not like historical allegory in fiction, and secondly that he began world-building long before WW2. He stated it was a lot more plausible that WW1 shaped the story, without admitting to an actual influence. It is as if he did not want his story to reflect modern times, but admitted there could be an influence from WW1.\n\nSome editions of LOTR contain Tolkiens little diatribe against WW2-interpretations as a foreword.\n\nI have read some of Tolkien's letters in their entirety, but primarily draw upon \"J.R.R. Tolkien: A Biography\" by Humphrey Carpenter, in the following\n\n- Tolkien had a standing grudge against the Normans and Saxons for disrupting Britain's oooold cultural heritage\n\n- In a letter to his son he wrote:\n\"My political opinions lean more and more to Anarchy ... or to ‘unconstitutional’ Monarchy. I would arrest anybody who uses the word State (in any sense other than the inanimate real of England and its inhabitants, a thing that has neither power, rights nor mind); and after a chance of recantation, execute them if they remained obstinate!\"\n\n- He supported Franco. Tolkien did not say Franco was great, but that the alternative was bussybody socialists who would spoil Spanish tradition.\n\n- He once wrote to a Belgian friend that Belgium has the appropriate size for a country, and that Britain should break up into pieces of that size.\n\nWhen you consider these opinions, other explanations seem as plausible as that he was influenced by WW1. For instance one could argue the story is about globalization. The good guys all are very tradition bound, while the bad guys develop new technology and want to spread. When Saruman gets control in The Shire he tries destroying the cultural heritage and rationalizes. He imposes laws where there only was custom and builds a state.\n\nSummarizing all this I would say: \"Maybe a little bit and indirectly, but Tolkien was more interested in industrialization and forced social change, and those motives fit the story as well\" "
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8iojov | why are there no underwater cities? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/8iojov/eli5_why_are_there_no_underwater_cities/ | {
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"Because it would be ridiculously expensive to build a city underwater... also it would be just nonsense. Why build a city where you need tunnels to get from A to B, it would be a nightmare on the topic of air circulation, some parts would need to be ankered to the ground to not float off Tides and algae would become an issue... its simply 10000x easier to build a city on land and until now we didnt need the extra room that would verify an underwater city",
"Almost all of the land surface is still available. Underwater construction presents a huge number of expensive and complex safety and logistical issues that are prohibitive when there's so much cheap land around.\n\nWhat happens when you break a window?",
"It would be massively cost prohibitive. It's hard and expensive enough to build stuff that is habitable and safe above water.\n\nHaving to make everything water tight, developing a system for pulling in air from the outside, or recycling the air would be complicated and costly.\n\nTransporting food and other goods underwater would also be more complicated.\n\nThere have definitely been some single structures that have been built to be underwater, but scaling it to a city is fraught with difficulty.",
"The cost and difficulty to build structure under water that survive the water pressure and can contain a atmosphere for humans to live in make it to expensive to build. \n\nYou will also have the limitation that you can leave the building as you are under water so you would have to be indoor all the time. There has to be be strict maintained as a failure is catastrophic.\n\nThere is no good reason to build a city underwater. We have enough unused areas on the land to build cities on. If we have limited area building sky scrapers are many time cheaper then a under water. Building a city down in the ground by digging out caves are a better alternative then under water.",
"Because ships might hit the skyscrapers (or landscrapers, as they would be called), and sink ",
"At the end of the day, most things get done because they provide a benefit without costing too much. Underwater cities would require a lot of work, a lot of engineering, and a lot of time and energy, and it wouldn't be any more beneficial than just making the city on land.\n\nThe only chance of seeing an underground city is if it was next to something so insanely valuable in the water that it was worth it to build a mining colony, and we haven't found anything like that.",
"Why would there be? There's no compelling reason to go through the trouble of building a city under the sea other than \"it's cool\". Cool don't make up for the massive inconvenience.",
"apart from it being unbelievably difficult and expensive to build, do you really want to live without sunlight?",
"There will be, once global warming raises the sea level enough.\n\nAlas, nobody will be living in them though.\n\n"
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280umz | Did the Mali Kingdom Reach America before Columbus? | I remember in high school world history class reading a poem about Mansa Musa's father Abubakr II. the poem said that his father set sail West with a very big fleet of ships and never returned to Mali. My world history teacher tried to imply that they could've reached the American continent because apparently there was some evidence in the records of the Europeans when they stepped foot on the American continent after the 1492. What do historians say about the Kingdom of Mali reaching the Americans via transatlantic sailing? | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/280umz/did_the_mali_kingdom_reach_america_before_columbus/ | {
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"Was it possible that someone from West Africa crossed the Atlantic before the late 15th century? Sure it was, just like it was theoretically possible that Chinese ships crossed the Pacific. It is however extremely unlikely, first of all because there was no *reason* to do so, second of all because the rich islands off the coast of Africa that were not visible from shore remained inexplicably uninhabited (which would make no sense had there been a major ocean-faring capacity in the general region), and third because we have absolutely zero evidence (besides oral history about the departure of a one-way trip) to suggest this was the case. There is no unexplained presence of African ecological or biological markers in American societies from that early a date, and no evidence of influence or borrowing aside from artifacts that extreme Afrocentrists have elected to analyze based on the conclusion they already believe. The historical consensus is such a firm \"no\" that most serious academic writers on precolonial Africa (Ehret, Thornton, et al) don't really even address the prospect beyond noting that the story exists.\n\nOne can never prove with certainty that something *did not* happen, especially when there is no evidence that authoritatively confirms or denies it. But the preponderance of evidence points to a negative conclusion--even though I would absolutely *love* for it to be true, because of the prospect for tracing elements of African society and culture that may precede the great shocks of the Atlantic Age."
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3mf48h | why are perpetual magnetic generators not a viable source of power? | Example video of what I am talking about: _URL_0_
| explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/3mf48h/eli5_why_are_perpetual_magnetic_generators_not_a/ | {
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"short and sweet answer: because there is no such thing as a truly perpetual magnetic generator. It is a physically impossible thing. anyone who claims to have one is either crazy or a con artist.",
"You know you have quality science when their is an add for a slot machine website in it.\n\nIt is probably a fraud, there is something driving the magnet. People have been trying to make perpetual motion from spinning magnets for a long time, and have yet to succeed. Mostly because it is impossible.",
"By driving the wheel with a relay and a primitive electromagnet, this guy gets his wheel to \"do work\", which is not exactly what you are looking for, but close enough. He uses lead acid batteries to power his wheel, and the wheel powers reciprocating motors that do work around his yard. _URL_0_\n",
"Ok, every kid has thought of this, \n\nYou make a wheel with tilted magnets on spikes, the idea is that by pushing away the part of the magnet that is closer to the opposide charged core, you can make the wheel spin indefenetly...\n\nIt dosnt work since the magnets would reach a point of equilibrium where all the forces cancel out and the wheel will stop. it will find the point where the forces are balanced and the repulsion is equal on all sides and stop there. its that simple. ",
"Why couldn't this work in space?",
"The laws of thermodynamics make perpetual motion impossible.\n\nNo matter how close you come to perpetual motion, energy is lost through sound or heat (friction) or some other means I'm not sure of.\n\nYou can obviously minimize those factors to be as small as possible and come infinitely close to perpetual motion, but you can never remove them.\n\nWith that being said, magnets don't create energy. There's no energy to harness from a contraption like the one shown in the video you linked.\n\nThe contraption is only losing energy. You can hear the sound of it spinning. The sound of it spinning is expended energy. \n\nThrough some hidden means, energy is being added into the contraption. Most likely there's just a small electric motor hidden beneath it.\n\n\n\n"
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1eukqv | How long did it take for feral horses to become ubiquitous in the great plains? Did they begin to populate right after the columbian exchange or did it take the centuries to reach 19th century levels? | I would like to expand the question: What Indian tribes best utilized horses? what societies dominated? how did the reintroduction of the horse alter the lives of plains people? | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/1eukqv/how_long_did_it_take_for_feral_horses_to_become/ | {
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"I'm sure somebody will be able to come along and expand. But I'll pull some information from the Native American history class I took. \n \nFor several centuries, the Spanish tried really hard to keep horses out of the hands of Native Americans, recognizing that horses were one of their biggest tactical advantages. And they succeeded really well for a couple hundred years. It wasn't really until the end of the 17th century that horses fell into Native hands. During the 1680 Pueblo Revolt, the Spanish were basically forced to flee New Mexico. When the surviving Spaniards retreated to Mexico, one of the things they left behind in the chaos was their livestock, including horses. \nComanche people were the first group to become a real \"horse society.\" By 1710, they were moving eastward at a rapid rate and came into major conflict with their Apache neighbors, who they virtually pushed out of their homeland over the next fifty years. They built a pretty massive trade empire in the Southwest, even treating Spain's New Mexico territory as a colony of the Comanche empire and forcing the Spanish to pay tribute or suffer increased Comanche raids. \nBy the 1750s, their trade network extended pretty far north. One of the more valuable trade goods was horses. The climate in the northern part of the Great Plains isn't really the best for horses, so it was the southern Plains tribes, like the Sioux, who became the really dominant horse powers in the area. \nAlong with altering inter-tribal dynamics (things like increased raiding/warfare and altering trade networks) the introduction of horses also fundamentally changed intra-tribal social dynamics. The most powerful guy in the tribe was now the guy who had the most horses. In the Sioux, dowries for brides were paid in horses. A system of horse \"rental\" was invented, leading to a kind of capitalism wherein one of the poorer members of society could \"rent\" some horses to use for a hunting trip in exchange for things like buffalo pelts. \n \nHope that helps. "
]
} | [] | [] | [
[]
] |
|
2pa62s | Do black-holes retain the properties of the matter they absorb? | For example, if a black hole was comprised mostly of material that was highly magnetic...would the black hole be magnetic?
If so, could such forces be used to contain/move smaller ones? | askscience | http://www.reddit.com/r/askscience/comments/2pa62s/do_blackholes_retain_the_properties_of_the_matter/ | {
"a_id": [
"cmvhwvi"
],
"score": [
2
],
"text": [
"As far as I understand it, the current understanding is that of all the matter that falls into a black hole, only the quantities which are strictly conserved in all physical interactions, i.e. mass, electric charge, linear momentum and angular momentum are conserved.\n\nSo, in a way, a strong enough electromagnetic field with the right properties could be used to manipulate and contain small, charged black holes.\n\nPlease correct me if any of that is wrong/incomplete/misleading."
]
} | [] | [] | [
[]
] |
|
3pvd8i | why is necrophilia so much more taboo than murder? | explainlikeimfive | https://www.reddit.com/r/explainlikeimfive/comments/3pvd8i/eli5_why_is_necrophilia_so_much_more_taboo_than/ | {
"a_id": [
"cw9rvzf",
"cw9sspp"
],
"score": [
4,
4
],
"text": [
"Victorian dogma about fear and revilement of death/respect for the dead that has lingered on. If we lived in a purely rational society, it would probably be possible to donate your body to necrophilia, because you are correct. Burying a dead body is throwing away a full set of valuable organs and tissues. It's a waste from a scientific and medical standpoint. And for a select few, a sexual one.",
"Because there can be good reasons to kill someone, but there is no good reason to fuck a corpse."
]
} | [] | [] | [
[],
[]
] |
||
22y8l3 | can you think of anyone from before 1970 who predicted that something like the internet would exist? | AskHistorians | http://www.reddit.com/r/AskHistorians/comments/22y8l3/can_you_think_of_anyone_from_before_1970_who/ | {
"a_id": [
"cgrldov",
"cgrmskh",
"cgrmtdh"
],
"score": [
14,
5,
4
],
"text": [
"Vannevar Bush, who conceptualized information technology in the 1940s (as opposed to mere _computing_: computers then were just meant to perform calculations). Douglas Engelbart, who invented the graphical user interface as we know it. Cf. [the mother of all demos](_URL_0_) from 1968, ([watch](_URL_1_))\n\nWhat I find interesting is that few science-fiction authors came close, if at all. Some did, but rather more recently. In fact it's rather telling that David Brin is considered prescient for his novel _Earth_ that predicts a number of things (such as blogs) rather astutely ... but that was in 1990. \n\nTake the mobile phone as a more specific example. Almost nobody thought about it. Except possibly Star Trek. Star Trek TNG invented the iPad. I find it interesting that it took that medium to come up with practical inventions, probably because, unlike book authors, its writers had to ask themselves how it would look like when people would interact with higher technology. \n\nWe could ask a more general question. Who in history predicted technological progress? The question is historically more profound than it may sound, in that it requires a concept of _progress_ that is so pervasive to our culture today that we have trouble relating with those in our past who did not have it. Instead, the common theme was that of the long lost _golden age_. ",
"Luhn's seminal paper from 1958, \"A Business Intelligence System\", predicted in many ways how information is disseminated today. From the abstract:\n\n > An automatic system is being developed to disseminate information to the various sections of any \nindustrial, scientific or government organization. This intelligence system will utilize data-processing \nmachines for auto-abstracting and auto-encoding of documents and for creating interest profiles for each \nof the “action points” in an organization. Both incoming and internally generated documents are automati- \ncally abstracted, characterized by a word pattern, and sent automatically to appropriate action points. This \npaper shows the flexibility of such a system in identifying known information, in finding who needs to know \nit and in disseminating it efficiently either in abstract form or as a complete document. \n\nIt's a bit hard to say if he predicted these systems or made they happen because of his work at IBM, but I think it does count, especially since his ideas are still relevant and fruitful.\n\nSome sources:\n\n- \"A Business Intelligence System\", LUHN, H. P., 1958.\n- \"Information Platforms and the Rise of the Data Scientist\", HAMMERBACHER, J., from the book \"Beautiful Data\", 2009.",
"[Nikola Tesla](_URL_2_) did predict something very similar to the Internet in 1900, with the World Wireless System.\n\n[Huffpost article: \"Did Al Gore Invent the Internet? No, Nikola Tesla Did\"](_URL_1_)\n\n[World Wireless System Wikipedia page](_URL_3_)\n\n[DamnInteresting article](_URL_0_)\n\nExtract from a 1908 article published in \"Wireless Telegraphy and Telephony\" magazine:\n > \"As soon as completed, it will be possible for a business man in New York to dictate instructions, and have them instantly appear in type at his office in London or elsewhere. He will be able to call up, from his desk, and talk to any telephone subscriber on the globe, without any change whatever in the existing equipment. An inexpensive instrument, not bigger than a watch, will enable its bearer to hear anywhere, on sea or land, music or song, the speech of a political leader, the address of an eminent man of science, or the sermon of an eloquent clergyman, delivered in some other place, however distant. In the same manner any picture, character, drawing, or print can be transferred from one to another place. Millions of such instruments can be operated from but one plant of this kind. More important than all of this, however, will be the transmission of power, without wires, which will be shown on a scale large enough to carry conviction.\""
]
} | [] | [] | [
[
"http://en.wikipedia.org/wiki/The_Mother_of_All_Demos",
"https://www.youtube.com/watch?v=yJDv-zdhzMY"
],
[],
[
"http://www.damninteresting.com/teslas-tower-of-power/",
"http://www.huffingtonpost.com/w-bernard-carlson/did-al-gore-invent-the-internet_b_3581391.html",
"http://en.wikipedia.org/wiki/Nikola_Tesla",
"http://en.wikipedia.org/wiki/World_Wireless_System"
]
] |
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