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2g5m7n
|
what is it about cast iron that makes it a "true non-stick surface"?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/2g5m7n/eli5_what_is_it_about_cast_iron_that_makes_it_a/
|
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"Basically, the \"burnt\" carbon in the oil fills all the little cracks in the iron, making it smoother. That's why you don't wash them with soap, so the carbon won't come out. If you have to re-season, or are starting with a new one, you'll have to coat it in oil and bake it in the oven 'til it smokes, then polish it down and repeat until it meets your standards. You also have to oil them before storage and burn that oil off a little before cooking with it the next time."
]
}
|
[] |
[] |
[
[]
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||
4lilfk
|
why can we have heaters but not coolers?
|
We have heaters that just turn electricity into heat but we can only cool things but moving the heat somewhere else. Why can't we cool things more directly?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/4lilfk/eli5_why_can_we_have_heaters_but_not_coolers/
|
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"Heat is a side-effect of electricity going through coils. It's a side-effect that we can use, but it means using the electricity pretty inefficiently. \n\nThere's no side-effect that'll make it suck the heat out of an area. That's the kind of thing you need to build a machine to do. And right now, the most efficient way we have of doing that is by moving the heat somewhere else. This need not involve electricity, but we still need to move it away. ",
"This largely has to do with how each process happens in the physical world, physics, with some chemistry.\n\nHeating things up is easy enough - bombard a thing with enough energy and that extra energy heats things up. This happens to be ridiculously easy with how we've harnessed electricity - just hook up the right kind of heat elements up that won't just melt due to the temperatures.\n\nCooling things down on the other hand usually relies on some form of chemical reaction. Usually as a matter of phase conversion - like a liquid into gas, this process absorbs some heat. Use the right chemicals that are undergoing that change and you can absorb quite a lot of heat. Even stuff like Dry Ice (which is really solidified Carbon Dioxide) and Liquid Nitrogen (made by cooling nitrogen gas to a point that it becomes liquid) operate on that fundamental property. We can't just throw electricity at something to cool it down - that adds energy to it, we need to take energy away, and the few ways we've figured out how to do that involve the changing state of chemicals.\n\nTo make a long story short, with our technology, we can add energy (heat) to things MUCH more easily than we can take energy out of things.",
"To put it very simply, it's because heat is a thing whereas cold is a lack of a thing. You can generate heat through various processes of converting one energy type (electrical energy or chemical energy) into heat energy. You can't generate cold because cold is just a lack of heat. So the only way to make something cold is by removing the heat."
]
}
|
[] |
[] |
[
[],
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|
1r2615
|
Why are people in the military refered to by their last name instead of their first name?
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/1r2615/why_are_people_in_the_military_refered_to_by/
|
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"Last names are often more unique than first names. ",
"Tradition, based on maintaining formality actually. First names breed familiarity. Must be professional (or appear to be) above all else.\n\nAlso, I was the only person in my company with my last name while there were several other guys with the same first name as me."
]
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[] |
[] |
[
[],
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10zu3t
|
What would be the most effective man-portable modern weapon to bring into combat against pre-firearms battle formations?
|
This question is somewhat theoretical, in that the greatest application of its answer would require working time travel, but the British did run up against a similar situation in Africa in the not too far distant past, so the question has some real world applications.
Let's say you have a small contingent of modern soldiers going up against a large army from the past (either a "Rome Sweet Rome" scenario, or fighting a Medieval army, or similar). What would be the best man-portable weaponry to use to effect a win? I'm restricting the question to man-portable because obviously if you could you'd just bring tanks and self-powered armored artillery and dominate a battlefield from a completely impervious position, but those technologies require supply lines (especially for fuel and maintenance) that you aren't going to have.
So, what weaponry would you bring to take on a large historical army? Remember, you may be dealing with armored knights, or cavalry, or archers.
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/10zu3t/what_would_be_the_most_effective_manportable/
|
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"That is impossible to answer because of the myriad number of tactics used and technologies throughout the ages. ",
"Whatever supplies the Pakistani weapons dealers use to make their own bullets and AKs with from scratch.\n\n[Linky](_URL_0_)",
"Probably the [Davy Crockett](_URL_0_), a portable nuclear weapon system. "
]
}
|
[] |
[] |
[
[],
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"http://www.youtube.com/watch?v=FinRqCocwGE"
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"http://en.wikipedia.org/wiki/Davy_Crockett_(nuclear_device\\)"
]
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|
9q2uys
|
why is it so difficult to memorize some of the things which we really need to whereas somethings we easily memorize without even putting in the effort to do so?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/9q2uys/eli5_why_is_it_so_difficult_to_memorize_some_of/
|
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"The amount of interest one has in the endeavor. Say for instance, as a language teacher, you’re teaching students that are either very keen on the subject or resistant to it due to the amount of interest they have in the language. The students who are more interested in the subject will always do better than the students who are in class due to parental pressure. \nAnother good example is when I moved to South Korea with my best friend, we both came to the country with an equal amount of knowledge of the language spoken here. I went on to learning the language far quicker than he did due to his lack of willingness to learn. But, we both also studied Japanese too, here he excelled at the same rate I did in Korean. \nThe brain has a tendency to turn off the recording mechanism when it appears to have found unimportant information, where as it records and holds onto information it enjoys or has an interest in. \nThis is just one example I’m giving to why somethings are memorized faster and longer than other things. From my experiences as an ESL teacher for 15 years in South Korea. ",
"typically because the \"useless\" things you memorize are of a type that was more useful to your ancestors. social structure (names, faces, people in general) are important to social cohesion, and thus survival. \n\nmath, dates, numbers, etc. are important today but didn't exist for most of human evolution. indeed, the type of computer your brain is seems to be inherently bad at linear calculation, the kind of things the machine you're reading this on is made to do. ",
"You remember stuff that you care about. I can still remember what bands made certain pop songs from 50 years ago. I was interested in pop music back then.\n\nI don't care for current pop music. I could try to memorise who recently recorded what and could probably do it in order to win a bet but a month later I will have forgotten it all.\n\nIf you **need** to memorise stuff that isn't interesting, there are tricks you can use. On the lines of making extremely silly connections to the data. \n ",
"Memory mainly works by meanings and associations. The more meaning you give something and associations you give it the easier it is to remember. For example the Memory Palace or Loci method employs imagining something to remember another thing since this is mainly how memory works. ",
"Think about the difference between \"memorize\" and \"remember.\" What are some things you have *memorized*? What are some things you *remember*? Most people would distinguish \"memorize\" as a list of information, facts, things someone has told you, while \"remember\" refers to something you experienced or which happened to you. I memorized the list of items to get at the grocery store from what my husband suggested. I *remembered* to get milk because I poured out the last of it this morning. You are more likely to remember things you experience because those items/events are directly relevant to you.\n\n & #x200B;\n\nThe fancy distinction for this is \"semantic\" (fact) vs \"episodic\" (event) memory. Episodic memory involves greater connectivity in the brain when being formed and when being recalled, intertwined very strongly with emotion. Because experiencing an emotion is often a signal that what's happening right now is REALLY IMPORTANT, a greater \"groundwork\" for that memory is laid in the brain. When sculpting that memory, your emotional state, current context (location, music you're listening to, people you see, ambient smells) also become part of that memory--I was tired when I poured out that milk this morning, I was listening to the traffic report on the radio, and I had just made coffee. So when I'm driving the store and pass by a coffee stand, yawning because I'm still exhausted, and the jingle for the hourly traffic report comes on the radio, I suddenly remember \"Oh yeah, have to pick up some milk!\" But when my husband rattles off a list of things he wants from the store, I don't have a particularly strong emotion, visual (or other sensory experience), or context that specifically relates to that information. It didn't happen directly to me, it didn't grab my attention very well, and it wasn't accompanied by a strong feeling. Why would my brain bother making this a memory?\n\n & #x200B;\n\nThis is why \"experiental learning\" can be so powerful--putting on skits in history class instead of just writing lists of dates and events, performing experiments in science class instead of looking at diagrams... Those create prolonged experiences accompanied by emotion and many other sensory \"cues\" to anchor that information. In fact, many \"memory tricks\" rely on creating even artificial/mental experiences to remember lists of information--when I was young I had a book to help kids remember state capitols using little cartoons and one-sentence visuals: A cartoon heart driving a car over a person's wound: Hartford, Connecticut. A field full of metal springs making creepy sounds: Springfield, Illinois. Those weird, cutesy drawings are appealing to kids, they grab attention easily, and each page had the image described TWO ways. The point is not to *memorize* the sentence, but to *remember* the cartoon. That creates a cue to remember the information later. This is similar to the \"Method of Loci\" technique, in which you pair items in a list of information to some route, location, or event you are already familiar with: \"I imagine myself walking into the house and put my keys on the table, where I see a carton of milk. I set my purse down on the couch next to a head of broccoli. As I go into the bathroom, I see that the sink is full of Spaghettios!\" Now when I go to to the store, I imagine walking through my house: I need to get milk, broccoli, and Spaghettios! I've tied this mundane list to a memory I already have, and which already has strong emotional connections for me.\n\n & #x200B;\n\nSo, to sum up, if you want to remember (not memorize!) information, act it out, make it personal, turn it into an experience.",
"A large part of remembering certain things is making some kind of noteworthy connection to it. \n\nLet's say you're trying to memorize the dates of the reigns of different Ancient Middle Eastern kings as I am right now. It's pretty difficult to memorize the very uncommon names and connect them with seemingly random dates and times. For example: Murshili II, whose reign started around 1.322 BCE. To make it easier to remember I made a mental connection between his name and some strange thought. In this case I figured his name reminded me of 'more chili'. Whenever I see his name now, I immediately remember the 'more chili' thought, which in turn sparks the connection with the 1.322 date.\n\nThis is a very specific (and conscious) example of something that happens very often without you even noticing. Certain pieces of seemingly trivial information get connected with another thought, and are therefor much more easily remembered. Simply trying to hard remember data without this additional connection is much more difficult. Instead of connecting data you're trying to ram it into a whole new set of data, which is much harder than adding it to an already existing pile of information.\n\nTL;DR - Adding information through means of connecting it with other information provides a bridge to help you remember, even if that bridge isn't very obvious to you.",
"Think of memory like a big spiderweb. Each strand is a different memory, feeling, or association. When you remember something new, it falls in the web. The more strands it hits, the more likely you are to remember it, and with more accuracy.\n\nYour senses, such as taste, touch, sight, hearing, smelling, and all the others (22 in total iirc) all have an impact on this as well. That's due to the context you already have built around those senses.",
"TBH this is just one of those things. You're only thinking that because you notice it. There's a billion things you remember that you had to remember for school. But you spend like 70% of your life outside of school so obviously a shitload of other things happen then too and you just happen to remember a thing here and there outside of school. And you're just thinking this because you happen to know a bit of trivia here and there but if you actually think about just random tidbits of crap you've learned from school, you've definitely remembered a ton."
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92hg0c
|
why does it seem that every company that updates their user interface makes it worse?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/92hg0c/eli5_why_does_it_seem_that_every_company_that/
|
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"text": [
"Because it changes from what you're used to, I'm sure if reddit changed from the new version to the old version there would be a lot more complaints. "
]
}
|
[] |
[] |
[
[]
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||
5twg4z
|
if passwords are stored as hashes why is it more secure to have passwords with numbers, capital letters, etc.
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/5twg4z/eli5_if_passwords_are_stored_as_hashes_why_is_it/
|
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"If the password database is stolen, or a security hole is discovered that lets the attacker try tons of combinations, they will probably immediately try a dictionary attack.\n\nThey'll check to see if any of the hashed combinations match common words and common passwords. This means that some will probably immediately fail as many people use the laziest passwords the rules allow.\n\nHowever, unpredictable capital letters or numbers ups the number of possible combinations tyou have to check to get the password, often to the point where it's so extremely time consuming that you just can't check all the hashes in existence.",
"Because it's much easier for a computer to guess \"password\" than it is to guess \"Leno43_dais%\". \n\nThe protection doesn't come from the fact that it somehow becomes harder for attackers to attack the hashes or server, that's always difficult. But an attacker can try out millions of passwords a second, the idea with password constraints is to get people to use hard-to-guess passwords instead of the name of their dog.\n",
"Let's say your username is \"user\", and your password is \"password\". *Important, never use this password or username.* The database of the website [hopefully](_URL_1_) is set up with a UUID (the System ID for a user), username and password something like this:\n\n UUID1: fe0c175d9f8329937f1e28a855dd571e\n UUID2: 6855692c7560f84a2fee41931c86b911\n\nThose series of letters and numbers are the hashed, or encrypted, username and password \n\n UUID1: user password\n UUID2: user2 password\n\nNotice that the hashed entries are completely different even if a single letter is changed or added. When you login, the computer can check if what you submit matches to a stored username and password, and if they do, you are granted access with that System ID (the UUID). If you're feeling adventurous, you can copy and paste on a Linux Machine the following command (if you're using MacOSX, substitute \"md5\" instead of \"md5sum\"):\n\n echo \"user password\" | md5sum\n\nYou should get the exact series of characters above for the UUID user password\n\nSo, if a server is hacked, the idea to make it as difficult as possible to figure out what the stored usernames and passwords are. A common technique is to write a program to try all possible combinations to try to break the password. There's additional techniques such as salting, which are outside this scope, that are used to increase the difficulty in figuring out what the password are, but the idea is if you can make your password complex enough initially, you buy yourself enough time to change the password. \n\nAs others have mentioned, a dictionary attack is exactly what it sounds like: a computer program that uses every possible word or word combination as a possible password entry. If you only have lowercase letters, then your password is very easy to break, [see here](_URL_0_). If you have upper and lowercase letters, numbers and symbols, then it is much tougher to break because of the possible combinations that can exist."
]
}
|
[] |
[] |
[
[],
[],
[
"http://math.stackexchange.com/questions/739874/how-many-possible-combinations-in-8-character-password",
"https://www.wired.com/2015/08/check-loved-one-exposed-ashley-madison-hack/"
]
] |
||
8wnydb
|
can poisonious creatures poison themselves, and if they can be poisoned is tolerance higher for them
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/8wnydb/eli5_can_poisonious_creatures_poison_themselves/
|
{
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"text": [
"Poisonous or venomous? Poisonous creatures you can’t eat. Venomous ones use poison on you (usually with bite)."
]
}
|
[] |
[] |
[
[]
] |
||
2r99u2
|
how is it that lower class people support the wealth gap/top 1% against their own self interest?
|
Definitely a charged/biased topic but I was just wondering.
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/2r99u2/eli5_how_is_it_that_lower_class_people_support/
|
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"text": [
"TO quote John Steinbeck: \"Socialism never took root in America because the poor see themselves not as an exploited proletariat but as temporarily embarrassed millionaires.\"\n\nYou can't vote against the oppressors if your one secret wish is to join them one day.",
"People are told that their economic problems are due to welfare queens and illegal immigrants taking our jobs. This exploits our natural \"us vs them\" tendencies and many people don't have the desire to examine complex issues in any in-depth manner. ",
"For the most part, poorer people want less income disparity. The problem is that poorer people tend to be less educated, which tends to makes them less able to critically examine what media sources tell them. Remember, the only reason a politician seems stupid is because you disagree with his/her platform. Without the ability to evaluate a platform and its effects on a socioeconomic class, poorer people tend to have to rely on other means of deciding who to vote for. So the most common criteria used are party affiliation (probably the most important and the most static), appearance/oratory skills, non-economic issues... Poorer people don't necessarily realize that the people they support aren't in favor of helping them. \n\nOr, and hear me out, maybe I'm wrong and the theories and policies held by lot's of the politicians poorer people are voting for are correct. After all, there is a large number of people who seem to agree with what they say. It's a complex issue and a viscous cycle and there's plenty of silly things to say about most voting groups and politicians.",
"Many forms of taxation effectively subsidize one group at the expense of another. There are a number of counter intuitive ways this can result in poor people subsidizing rich people.\n\nFor example, most expenses related to road construction and maintenance come out of income, sales, and property tax, the gas tax doesn't cover it. So among drivers, it means that people driving the least subsidize those who drive the most. Worse still, a lower income person who can't afford a car at all, still pays almost as much for the road (sales tax, income tax, property tax) as a low income neighbour who does own a car.",
"The 1% exploits fear, ignorance, societal divisions (race, religion, immigration status, etc), and, as others have mentioned, optimism. \nIt works the same way as house blacks on a plantation - keep them afraid of reprisals, hopeful for benefits, proud of their status over others and unaware of the larger truths and they will help you keep the unruly mob down. This is a story as old as civilization."
]
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78khw5
|
what does "bulking" (for bodybuilders) do to your body in a biological sense?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/78khw5/eli5_what_does_bulking_for_bodybuilders_do_to/
|
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"bulking means gaining weight. the bulking phase optimally gains muscle but gaining fat is not avoidable. a bulking phase followed by a cutting phase will reduce the body fat to desired levels once muscle mass goals are reached. ",
"You're eating to give your body an abundance of the materials it needs to make muscle. You will eat more calories than you burn (so you aren't using up stored energy) and you'll eat a surplus of proteins (so you have enough amino acids which are the building blocks of proteins). You do this so when you work out your body is in the ideal situation for building more muscle.\n\nThis is in contrast to people who want to lose weight and work out in order to burn more calories than they consume. This forces the body to use up what you already have and thus lose weight."
]
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|
[] |
[] |
[
[],
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||
3f3a74
|
How can ants count their steps? We've developed numbers as a system of organization and measurement, so we can literally speak "1, 2, 3" but how can an insect keep track of the amount of steps it has taken?
|
askscience
|
http://www.reddit.com/r/askscience/comments/3f3a74/how_can_ants_count_their_steps_weve_developed/
|
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"text": [
"The authors of the study that I believe you are [referring](_URL_0_) to weren't sure what internal mechanism is guiding it. And this paper was put out nine years ago and I don't see anything on it since then. However insects and animals in general are capable of doing things we think have to think about (counting for example) instinctually. Same idea with termites \"knowing\" how to design their mounds so that they naturally have efficient air circulation or honey bees build honey combs with hexagons in such an efficient manner. Natural selection has selected for ants (unsure if the entire formicidae family can count like this as the study only used foraging saharan desert ants, *Cataglyphis fortis*) that can count their steps to, as the authors believe, aid in navigation."
]
}
|
[] |
[] |
[
[
"https://scholar.google.com/scholar?hl=en&q=ant+counts+step&btnG=&as_sdt=1%2C18&as_sdtp="
]
] |
||
1sj89p
|
when a gaming company develops a new 'engine', what have they actually done?
|
Thought of this after seeing the Snowdrop engine from The Division.
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1sj89p/eli5_when_a_gaming_company_develops_a_new_engine/
|
{
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"So I have no experience with game programming in particular, but a lot of experience with other types of programming and with physics.\n\nBasically when you write good code you reuse a lot of the old code. So in time this process has been streamlined into \"libraries\" or a large groups of code which works well together. They call a massive group of physics library an \"engine,\" cause it \"drives\" the physics of a game. So if you can write up all the rules for a good physics engine you can make the game do whatever you want. Like have a man ride a bicycle, have a bunch of dudes beat another dude up or have a grown man ride a pony. Same laws of \"Physics\" apply in all situations so they can use the same game engine. \n\nHere is an example of a such a libarary _URL_0_",
"A game engine is kind of like a programming language, for describing the sorts of things that a given game has to represent. So when a programmer is actually writing the game, s/he doesn't have to program the exact response of the environment to every little thing. \n\nFor example, in a first person shooter game, you might move your character by pressing the arrow keys. A programmer could hand code every aspect of every movement: if you enter a room and press \"up\", for 2.1 seconds, they can hand code exactly what that does to the two dimensional image on your screen, to make it look like you walked into the middle of the room. That shift in perspective would be calculated for every key press you make. They'd also have to hand code what would happen if you hit \"left\", \"right\", or \"back\". It would be a tremendous amount of work! Just coding a room based on all the possibilities of movements would be a bitch. Yes, that's a technical programming term.\n\nInstead, we have a concept of layered programming. This means that one layer (often called a library) establishes some base concepts in a way that is re-usable, and exposed to other parts of the program. Then another coder with a different specialty can come in and just use those concepts. To continue with our FPS example, the game engine makes the computer build a sort of mental model of 3D space, and defines just how much movement to take for a step of X duration in a particular direction. It might define how much the player's perspective should bob to make it feel like a footstep, and a bunch of other variables that make it feel like a natural movement. This would be a game engine. Then a different programmer can come in and use that library. She might just have to define the movement keys, and all that work is already done for her. This lets her focus on other elements of the game, like the layout of rooms, doors, obstacles, and opponents. \n \nOf course, a game engine for a modern game can handle a lot more than walking in different directions! For instance, if you use the Unreal^TM Engine, it handles walking/running/jumping, different kinds of projectiles, falling objects, displaying opponents, etc. You could pick up the unreal engine, and spend your energy on other aspects of the game like the map layout, the look and feel of the weapons, the walls, the look of the players, etc.\n\nOn a more abstract level, you could say that a game engine is the part of the program that handles physics, and making things look/feel realistic. The rest of the game builds on that to tells a story and create an experience for the player."
]
}
|
[] |
[] |
[
[
"http://en.wikipedia.org/wiki/OpenGL"
],
[]
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|
4tq056
|
why does the writing on tires in motorsport appear to spin in different directions at different speeds?
|
For example, [here](_URL_0_). The writing on the front wheels appears to be rotating in different directions at different speeds. Why is this?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/4tq056/eli5why_does_the_writing_on_tires_in_motorsport/
|
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"text": [
"What you are watching is a recording made by a camera. The camera shoots a certain number of frames per second, and each frame is a snapshot of what is visible at that moment.\n\nIf the wheel happens to rotate through a little less than a full turn, say 350 degrees, in the time between one frame and the next, then this will look no different to a rotation in the opposite direction of 10 degrees. If the wheel continues to rotate at the same speed, the next frame will look like a rotation of another 10 degrees in the opposite direction, and so on.\n\nPresented with a sequence of images rotated by 350 degrees from one to the next, your brain takes the easy route and interprets these as rotations of 10 degrees each in the opposite direction. You have no way of forcing yourself to see it as it actually is, and so the wheel appears to be rotating backwards.\n\nCompare the [barber pole illusion](_URL_0_), where a rotating stripy pole appears to be moving upwards rather than rotating.\n\nIf you were watching this live, then the writing would be a blur and the wheel would not appear to be rotating backwards."
]
}
|
[] |
[
"https://youtu.be/hlaaj_E39iM"
] |
[
[
"https://de.wikipedia.org/wiki/Barber-Pole-Illusion#/media/File:Barber-pole-02.gif"
]
] |
|
20f5op
|
why can't we use human poop as fertilizer?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/20f5op/eli5_why_cant_we_use_human_poop_as_fertilizer/
|
{
"a_id": [
"cg2mz74"
],
"score": [
4
],
"text": [
"Ever heard of *night soil*?\n\n > The reuse of feces as fertilizer was common in Japan. Waste products of rich people were sold at higher prices because their diet was better; therefore, more nutrients remained in their waste. Various historic documents dating from the 9th century detail the disposal procedures for toilet waste.\n\n[Night Soil (Wikipedia)](_URL_0_)"
]
}
|
[] |
[] |
[
[
"http://en.wikipedia.org/wiki/Night_soil"
]
] |
||
70rvh6
|
In terms of evolution, why is vitamin D synthesis dependent on exposure to sunlight?
|
askscience
|
https://www.reddit.com/r/askscience/comments/70rvh6/in_terms_of_evolution_why_is_vitamin_d_synthesis/
|
{
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"text": [
"I'm not sure which direction you are thinking about this from, so I will answer both questions simplistically. Feel free to ask for clarification.\n\n1. Why haven't we evolved to produce vitamin D without sunlight?\n\nAll organisms which use the chemical (as far as I'm aware) from phytoplankton to mushrooms to mammals synthesize vitamin D by the use of sunlight, (or by eating something that did) Biology simply hasn't come up with a better way to do it. Most species get enough sun exposure that they really don't need a \"better\" way, but there are enough species that would probably benefit that it's probably a safe assumption that there isn't a simple way to synthesize it without UV. (Keep in mind, natural selection works in tiny increments, where no increment can be too detrimental to survival)\n\n2. Why would we evolve to need a chemical that we need sunlight to produce?\n\nUltimately sunlight is so important to most organisms (either for their own photosynthesis or for their food's photosynthesis) that the benefits of D outweigh reliance on getting a few minutes of exposure every day. After all, they're going to be in the sun anyway.\n\nOrganisms which don't have reliable access to sunlight or nutritional D just don't use the chemical, or don't use it for essential functions.",
"Vitamin D is a fat soluble vitamin found in nature as one of three types Vitamin D1, Vitamin D2, and you guessed it, Vitamin D3. As with all other substances on earth there is a finite amount of each. The absorption of these vitamin components is dependent on an intact brush border in the proximal small intestine. Some is absorbed without, but best absorbed with fat in the diet. An intact liver and kidneys are needed for best conversion and absorption. UV radiation converts D2 to D3. This occurs in the subepithelial dermis and requires adequate levels of D1/D2. There is a feedback mechanism which regulates need for Vitamin D which is calcium bound and co regulated by PTH(parathyroid hormone). This is a guess but my bet is survival of the fittest when it comes to sunlight needs. Those who are in sunlight(hunters) probably need more Vitamin D than those not in sunlight(cavedwellers) to support good solid bone and muscle growth to compete with other predators.",
"This is something I've wondered for a while and I've failed to ever find a satisfactory answer. The questions I have are, can the conversion performed by UV exposure be done enzymatically? If so, why isn't it? Are there any examples of an organism converting 7-dehydrocholesterol to vitamin D3 enzymatically? I have no data to support this, but my hunch is that it's much more efficient and convenient to use UV. 7-dehydrocholesterol is made from a precursor for cholesterol, so it's already abundant in serum. Simple and reliable photoconversion to vitamin D3 may be a rare case where it beats out any enzymatic pathway to do the same job. If you look at the intermediates, UV exposure readily causes reversible interconversion to different related molecules. The body just sequesters the D3 into binding proteins as it's made. There are no non-reversible/undesirable conversions from UV,. In a sense, it's also a big evolutionary advantage. Metabolic pathways are complex and it may be there was simply not enough pressure to go that route. That being said, I wouldn't be surprised if we found some simple organisms in low light environments that found a different way."
]
}
|
[] |
[] |
[
[],
[],
[]
] |
||
2a75qo
|
why is it that sometimes i can be more tired after a long day at school than a long day doing physical labour.
|
Recently I've been working 12+ hours doing physical labour. I thought I'd be exhausted, but I find that I'm more tired after an 8 hour day of school.
ELI5?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/2a75qo/eli5why_is_it_that_sometimes_i_can_be_more_tired/
|
{
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"text": [
"The brain consumes more calories than the muscles in your core.\n",
"Well, for one thing you don't do physical labor 12 continuous hours. You take breaks and such and you give your muscles a chance to recover. It's easy to figure out when you are hitting physical limits because of pain. \n\nMental limits are harder.\n\nIf I asked you to jog in one place for 15 minutes, how would you feel? Out of breath? Tired? Muscles starting to ache? \n\nAsk you to concentrate for 15 minutes, how do you feel? Eh, okay. \n\nBurning up a lot of calories either way. Stimulating nerves like crazy. But without lactic acid and other signs of fatigue, we don't always realize how much effort we are putting in.\n\nThat's half the answer.\n\nOther half is more emotional. When you are at school, you're having lots of information tossed at you, you've got to do a lot of time based tasks, you've got to remember a lot, you're under pressure, right? That's stress right there.\n\nWell, funny thing is that our bodies aren't really designed for high stress scenarios with little danger. In a natural setting you should feel stressed pretty much only when you are in danger. A tiger is coming after you, you need to run. Pump up the adrenalin, get the heart racing, flood the muscles with blood, raise blood pressure, frantically look around for anything that might save you . . .\n\nAnxiety and stress are pretty good when you need to flee (or fight) and need your body pumped up for maximum performance in a hurry. Not so good when you need to remain still. It's also only meant for a quick burst of energy. A long frustration 8 hour stretch of having your body gear up and down for a threat that never comes exhausts it.\n\nShort version: When you are physically working it is easier to note limits. Mentally working it is harder. Plus human bodies suck at dealing with prolonged stress when running away isn't an option.\n\n"
]
}
|
[] |
[] |
[
[],
[]
] |
|
fwpcbr
|
During the glorious revolution of 1689 William and Mary of Orange became the king and queen of England, Scotland, etc. But did they keep their power as ruler of the Netherlands? If so, does that mean that the UK and the Netherlands were the same country for some time?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/fwpcbr/during_the_glorious_revolution_of_1689_william/
|
{
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"fmq440b"
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"text": [
"First question: Yes, William (not Mary) maintained his position as Stadtholder of the Dutch Republic. It's worth nothing that though officially dual monarchs of England, in practice William took the leading role even while Mary was still alive.\n\nSecond question: You can quibble about this, but I'd say in principle, no.\n\nFor this, you need to understand that England and the Netherlands under William III were not absolute monarchies.\n\nThe Netherlands was a Republic and William's position was more comparable to that of a parliamentary president and commander-in-chief for life as opposed to a traditional monarch. I.e. his position was that of a servant of the state, and his power was heavily circumscribed by the rights and politics of the provinces and cities as represented in the States General. In particular the patrician government of the city of Amsterdam with its massive wealth and thus considerable influence on the national budget, was a constant power factor for William III to manage. One that often went directly against the policies desired by William.\n\nIn England the power balance between the monarch and parliament had been a continual issue for at least a century, leading to a history of armed conflict of which William's invasion was the latest chapter. William's success in achieving a largely bloodless victory (in England, the situations was quite different in Scotland and Ireland) lay in part in William's strategy of applying the lessons he'd learned in the Dutch Republic to managing his relationship with the English parliament. William, in principle, was experienced with and prepared to accept a more subservient position to parliament than many of his homegrown predecessors could stomach. This was aided by the fact that William's invasion of 1688 had been largely motivated by foreign policy, England's position in the continental balance of power, in which William saw England as a crucial 'swing vote' determining the Dutch Republic (and the whole of Europe's) security or insecurity versus the power of Louis XIV's France.\n\nThus, under William III, the foreign policy of England and the Dutch Republic became largely the same, i.e. anti-French, and in that sense you could argue that they were sort-of the same country.\n\nBut I think that the question implies a much stronger union, which there never was. Though there was a considerable exchange of knowledge and people (quite a few Dutch aristocrats and merchants used the opportunity to immigrate and become English aristocrats and merchants), with the exception of William himself the governments of both countries continued to function largely autonomously. There was no merger of the Dutch States General and the English parliament, domestic policy remained entirely local to both, and foreign policy was only harmonized in so far as William managed to get his way in both the States General and parliament (which was never assured and rarely easy.)\n\nThis is also why when William died the union dissolved pretty much immediately. Its legacy being primarily England's geopolitical foreign policy, which was continued largely along the course William had set it on, with England remaining an ally to the Republic and a counterweight to French hegemony essentially up till the French threat was replaced by the German threat (barring, of course, noted low-points in Anglo-Dutch relations such as the fourth Anglo-Dutch war.)\n\nSomeone else might have another take on any specific detail, but I think this is the tl;dr of what you were asking about."
]
}
|
[] |
[] |
[
[]
] |
||
9iwsyx
|
since our cells are always multiplying, does a 90 year old have more dna in their body than a newborn?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/9iwsyx/eli5_since_our_cells_are_always_multiplying_does/
|
{
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"e6n01lj"
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"text": [
"Yes, an adult has more cells, thus more DNA, than a newborn.\n\nBut once you reach full size, you stop increasing the number of cells. New ones are born and old ones die. So a 90 year old has about the same amount of cells and DNA as a 20 year old."
]
}
|
[] |
[] |
[
[]
] |
||
1qdbpg
|
how does the hard disk save my data, when my computer is shut down?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1qdbpg/eli5_how_does_the_hard_disk_save_my_data_when_my/
|
{
"a_id": [
"cdbo933"
],
"score": [
6
],
"text": [
"Through magnetism.\n\nImagine that there are billions of small magnets inside your hard drive. When your computer writes something, it arranges those magnets in a particular way. You need electricity to do that. But once you are done, the magnets will stay in their place regardless of whether you have power or not."
]
}
|
[] |
[] |
[
[]
] |
||
1m4csp
|
why doesn't apple broadcast their product announcements
|
It seems like whenever a new Apple product comes out there's a big event and lots of different tech sites "liveblog" the presentation. Why don't any of them just broadcast it live or post it on their website after it's over so I can watch from home? Why doesn't Apple broadcast it on its own website?
(Example "liveblog" _URL_0_)
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1m4csp/eli5_why_doesnt_apple_broadcast_their_product/
|
{
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"text": [
"Apple usually provides a video of the event on their website that evening or the next day. The reason they don't broadcast it live or provide the video earlier is because they'd essentially be stealing traffic from the tech blogs, which they want to maintain a good relationship with."
]
}
|
[] |
[
"http://gizmodo.com/our-iphone-event-liveblog-starts-right-here-on-9-10-at-1277167537"
] |
[
[]
] |
|
6ng1yj
|
Is there evidence surgical masks being worn by people who are ill significantly help limit infection of others?
|
I know this is common practice in Asia and, particularly in places with high population density and in tight public quarters it makes sense, but is there evidence this significantly helps reduce infection rates, or is this mostly an old wives’ tale?
|
askscience
|
https://www.reddit.com/r/askscience/comments/6ng1yj/is_there_evidence_surgical_masks_being_worn_by/
|
{
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"text": [
"\"For many years, scientists weren't sure if wearing a mask was effective at preventing the spread of viruses. However, recent studies suggest that they can help.\n\nFirst, a 2008 study published in the International Journal of Infectious Diseases concluded that when used correctly, masks are highly effective in preventing the spread of viral infections. Family members of children with flu-like illnesses who used the masks properly were 80 percent less likely to be diagnosed with the illness. Surprisingly, the difference between types of masks used was insignificant.\n\nAnother study published in the Annals of Internal Medicine reported similar results. Researchers looked at 400 people who had the flu. They found that family members reduced their risk of getting the flu by 70 percent when they washed their hands often and wore surgical masks.\"\n\n_URL_0_\n"
]
}
|
[] |
[] |
[
[
"http://www.ijidonline.com/article/S1201-9712%2808%2901008-4/fulltext"
]
] |
|
12p6st
|
Help me identify a dogtag I found
|
I found this [dogtag](_URL_0_) on the floor of my garage. As far as I can tell, it is WWII era, as there is not a notch in it. What is odd though, is it seems to be much thicker because the text is not punched through. It is also unused.
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/12p6st/help_me_identify_a_dogtag_i_found/
|
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"text": [
"Nope. What you have is NOT what you think you have. WWII dog tags looked like this: _URL_0_",
"Just an observation but I have never seen authentic dogtags that say \"name:\", \"rank:\", etc. Dont they normally just put that information? Also I know in several versions the blood type is listed or even religion can be listed. \n\nperhaps its ornate? something like these _URL_0_ \n",
"This is almost guaranteed to be some sort of civilian copy. First, I have never seen a WWII era dog tag that looked like that. Second, there is no reason to have rank on a dog tag. Ranks change, especially during war. "
]
}
|
[] |
[
"http://i.imgur.com/707lm.jpg"
] |
[
[
"http://www.dogtagsrus.com/images/Dogtag_History/Renney1_ea.jpg"
],
[
"http://www.craigsclassifieds.com/wp-content/uploads/2012/08/164736-500x373.jpg"
],
[]
] |
|
1gv6tl
|
what do real spies do? how are they recruited? do they actually have the kind of gadgets we see in bond films?
|
There were a lot of great answers, but I think these two were the most explanatory:
_URL_0_
_URL_1_
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1gv6tl/eli5_what_do_real_spies_do_how_are_they_recruited/
|
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" > there doesn't seem to be anything here",
"You're not going to get an answer here. If anyone on reddit knows anything about this, they are a spy. If they are a spy, they will not tell you. \n\nThis is our daily dilemma. ",
"While you won't get anything about modern spies, if you check out some spy history, you'll find that there are some really interesting things. \n\nI while ago, I visited a spy museum, and man that was the most worthwhile money I spent in a long time.",
"There was a really good BBC documentary based on GCHQ and MI6, which is based on counter terrorism and interrogation. Field agents weren't shown to be 007, more like average joes in disguise.",
"You might want to ask /r/AskHistorians. They probably can't give you an idea of what current spies do, but they can definitely give you an image of what spies in the past did, even as recent as the Cold War.",
"A kid I went to middle school with got convicted of espionage. He was just meeting with foreign people giving them information.\n\n_URL_0_\n\nThough it doesn't seem like he did a great job of it from the article. ",
"Agents are generally recruiters and they get others to work for them. Instead of learning a language flawlessly and elaborate disguises and stories and daring capers, you generally just pay people who already blend in who you know have access the intelligence you want.",
"I had a friends father that used to work in Intel departments for the pentagon, cia,etc. I asked him this question over a beer and he gave me a very simple answer.\n\nSpies of governments usually act the same way lobbyist do. They rarely use direct interaction to gather Intel or pursuade action. Instead they might become friends with an important persons niece or confidant. Gathering rumor or general ideas from various viewpoints. This is not just 1st world govts that do this.",
"No, not like Bond films. Nothing in a Bond film has ever been invented by the time of the movie's release (with the exception of Q's latest appearance. We do have radios. Though I think the palmprint gun is a bit of a stretch. Not outside our capability to make, but I don't think we've actually done it.) Anyway, most of the \"gadgets\" or tools rather, are probably along the lines of concealed poison capsules, small cameras that can be hidden in a coat. Small places for knives to be stored, etc.",
"I don't know about the US but if you want to be a spy in the UK, go to the M16 website and look in jobs. There are a number here so look under 'intelligence agent' or something like that. There is nothing in the description that directly says that this is the spy job, but reading between the lines it becomes pretty obvious. ",
"If you're really interested, Stuff You Should Know has a 40 minute podcast answering every single question you asked. It's incredibly interesting and not terribly hard to understand.\n_URL_0_",
"Well, what you're thinking of as \"spies\" is called [HUMINT](_URL_0_) (\"human intelligence\"), and more narrowly, [clandestine HUMINT](_URL_3_). Wikipedia even has a useful article on [espionage techniques](_URL_1_).\n\nBut basically, it's about discovering people in the target country who can be convinced to help the country that's doing the spying—without getting caught. So a lot of it comes down to socializing with a lot of people, learning about them and whether they may be of value, judging their character and motivation, finding which ones are likely to say \"yes\" and convincing them. Most of that is not very movie-like, but in rare occasions you get things like blackmailing somebody into spying against their country.\n\nThere's another set of techniques that are a bit more movie-like, having to do with secret communication and delivery of documents or materials. There you do get things like [numbers stations](_URL_2_) (shortwave radio stations with people reading lists of numbers, widely understood to be coded messages for spies), hiding a suitcase in one location for another spy to pick it up, etc.",
"In the UK you can apply for a job as an 'intelligence analyst' with MI5 through a simple application form:\n\n_URL_0_\n\n",
"If you want a real answer, read some of John le Carré's older books, such as The Spy Who Came in from the Cold, Tinker Tailor Soldier Spy, The Honorable Schoolboy, A Perfect Spy, etc.\n\nJohn le Carré actually worked for British intelligence when he started writing his novels. They're fascinating and not glamorous at all. ",
"I'm sure someone has better examples, but here goes:\n\nKnow what reporters are supposed to do? Talk to people, review publicly available information, cultivate sources, that kind of thing?\n\nThat's human intelligence.\n\nKnow how reddit loves to pore over photos looking for hidden things in an image and trying to understand and identify all aspects of the picture?\n\nThat's image intelligence.\n\nYou've seen those alternate reality games where you try to decode a string of letters to an imgur link or similar? Little games to find the hidden meaning?\n\nThat's signals intelligence.\n\nSpotted some shills on reddit for some cause or product? You know, the ones that never have anything bad to say about X, defending it beyond reason?\n\nThat's propaganda.\n\nKnow the people who spot the shills and call them out?\n\nThat's counter-intelligence.",
"When I was in graduate school, the CIA was openly recruiting at my college for a position called \"clandestine operations\". \n\nI didn't apply.\n\nEdit: and they advertise jobs on their website too: _URL_0_",
"My dad worked in the intelligence community for over three decades. He was initially recruited out of the military, and once had a job interview in a bar in a foreign country. He spent most of his time scrutinizing photographs. I don't really feel comfortable going further into what I know about what he did until I see how much he would be able/willing to talk about. I'm going over to his house tomorrow, I'll see if he's got any interest in doing an AMA or something.\n\nEdit: I guess I should mention that he has [written a novel](_URL_0_) that has already been cleared through his former employers. If amazon goes out of stock, or if you want a signed copy, send me a message and I'll arrange it.",
"You job is to befriend people who have weaknesses. Where do disgruntled employees go to let off steam after work? You go to these places. You become a regular, blend in, and become accepted. Make friends with the ones that work at your target's company. \nYou get them to trust you, to confide in you, and to eventually share their insider view of your target. \nYou exploit them by getting them to discuss details about the target after some time. If they are willing to share enough info, you move to the next step. \nPause, hello NSA, how's it going? \nBack to the topic. \nIf your new friend does not have enough information, you convince them to help you get it from another employee who does. You form a network of employees who are disgruntled until you find one that has the key to what you need. \nOften, the honeypot or money are not needed to convince them to help with small information bits. Many times people simply need to feel like they have friendship. Human weakness is the need to belong. \nThere are others of course, who are more powerful, more influential, and more self confident. They will require bribes, sex, or offers of power to convince. The highest level turncoats demand sanctuary, because they realize that yielding what they know will be an immediate death sentence for them. \n1. Finding these weak employees via finances and relationships. \n2. Assigning the correct individual to befriend them. \n3. More field time to track their habits. \n4. Field time actually nurturing the relationship. \n5. Bringing resources in to help coddle the relationship. \n6. Providing more resources to help the employee with their task to acquire the information you want. \n7. Providing the necessary escape plan resources for the agent and/or employee should the data retrieval go bad. \nAll of these steps are accomplished by a team of workers. A single target can represent an operation that takes years to accomplish. Recruiting an employee to recruit an employee...et al...can take years and easily break a 200k annual budget on its own. The hardest part of running these operations? Choosing which targets are the most cost effective to start one of these operations on.",
"This is for \"commercial intelligence\", not national intelligence, but [Confidential](_URL_0_) by John Nolan is a very good, nonfiction, explanation of modern spycraft. I heard Nolan speak at a conference, and immediately resolved never to say anything, to anyone, ever.\n",
"Hypothetically,\n\nA spy today is not what a spy was fifty years ago. Government agencies such as the NCS and the NSA rarely go into the field as much anymore. Most often the work is done by analysts taking in hard data and scouring it for intel.\n\nThis is called chatter. It's picked up from listening posts, satellites, wire taps, and many other ways. Then it is processed by Analysts and translated into actionable intel.\n\nHowever clandestine operations often require people on the ground, as the international waters get muddier, no agency can afford to have a citizen of their nation be caught doing things that would be considered espionage.\n\nThis is where certain individuals come in. Most often they are colloquially referred to as contractors. They are citizens of some nation, who usually have armed forces training, they can have criminal records, speak multiple languages, and generally aren't very social.\n\nThese people are paid, to do their work. But they are not employed by a national government. It is not an easy field to get into, as most seem to stumble upon it by chance, but once you are in it's quite difficult to get out. These people act on actionable intel. They follow, they watch, they take pictures, they monitor, they course correct.\n\nSometimes, very rarely, they have to take a direct approach, retiring a target or an asset is unpleasant but it can be necessary for security purposes or for the mission itself.\n\nThis is where gadgets come in, but not really the sort you'd think of. A gun is a very specific tool and a good contractor doesn't carry one (most of the time). The tools we get are small, practical and made with purpose. They can be simple chemical compounds, or practical applications of every day items.\n\nThese are used to retire people. It's infinitely better to have a public figure, or political target, or even a known person expire from natural causes, or accidental causes, than a bullet.\n\nBullets raise questions where you would prefer none are asked.\n\nI hope I could hypothetically shine a little light on this shady subject for you.",
"nsa watching this thread so hard",
"There are two types of \"spies\" - official cover and non-official cover. Official cover is much more common.\n\nOfficial cover spies work out of an embassy, typically with diplomatic immunity - although with a false agency (eg: Department of State instead of CIA). If they get discovered, they get sent home at the host country's request.\n\nNon-official cover spies are more rare (for the US anyway) and its riskier. If they get caught, they have no rights so the host country can do whatever it wants with them. Typically, they'll be jailed and used to get back the host country's captured spies in an exchange.\n\nBefore we continue, its important to note that the US has never really been an \"agents on the ground\" country like other nations (esp. Russia with the GRU and Israel's Mossad). The US has always been infatuated with technology - this lack of human intelligence has been a huge sticking point over the past few decades. 9/11 was something of a wake up call and they've been trying to ramp it up, but the institutional knowledge just isn't what it should be.\n\nAnother side note - more agencies \"spy\" than just the CIA. A lot of agencies have their international representatives (military attaches to embassies for example) writing intelligence reports. \n\nLet's narrow the scope of our discussion somewhat and deal just with CIA agents - the folks you're probably talking about when you say spy. At the core, both official and NOC agents do the same thing - and if everything goes right, it's a boring job. They don't do any spying themselves - instead they recruit locals to do this for them. They construct networks of people (spy chains, spy networks) that can get access to the information they want and use those people to collect intel. They typically recruit people using one of the following motivations: blackmail, nationalism (\"this will be good for my country, the people in power are bad!\"), sex, money or long term promise of becoming a US citizen. Often, only one or two people will know the agent's identity, these are the heads of the spy chain and act as cutouts - representing the agent inside the network in order to keep the agent safe and the agent's nation secret. At its core, agents are charismatic and unassuming - they go unnoticed and \"sell\" locals on spying for them. \n\nAt the other end of the spectrum, the CIA does recruit from special forces and has their own paramilitary force. I don't know much about how they're employed currently. In Vietnam they played alongside other SF forces and conducted similar missions. Up until Obama, they didn't see a lot of action. In fact, Obama's conducted more paramilitary strikes than any other President since the Church Accords way back in the day (he favors it over overt military action).\n\nThe gadgets do exist, in a sense. But they're just things like ways to hide bugs and concealable cameras/AV equipment. \n\nSource: I'm a nerd.",
"They have to look and listen, so I guess you're out.\n\n_URL_0_ is a book I read a while back. [Lindsay Moran](_URL_1_) writes about her life in the CIA. There is survival training.",
"If you mean specifically US spies: [CIA Special Activities Division](_URL_0_). They are the ones that perform HUMINT/human intelligence, which is the \"traditional\" type of spying you see in movies, the gathering of information from people. They also perform covert political action (destabilisation of regimes) and paramilitary operation. These are the people that the US denies knowledge about if they are compromised. Generally they are plucked straight from the Delta Force, Seal Team 6, and Air Force Special Operations. As for gadgets, very likely yes. The most badass thing you'll read this week is what kinds of training they do, as well.",
"I can give you only an anecdote from back in the 50s. My dad was a milkman and made his deliveries between 2 and about 6 in the morning. A CIA agent came to our house and asked my dad if he would take notes on anything he saw or heard in the vicinity of a certain house — what kinds of vehicles were parked there, their license numbers, how long they stayed, whether he ever saw persons of a certain description on the property, etc. My dad took on the assignment and met with the agent regularly for months.",
"Unfortunately, spies (Mi5/Mi6) in the UK are comically underpaid, barely making $30,000. I think CIA agents are paid rather well, though.",
"If you're wondering about field agents with Bond-style combat and weapons training, they're usually recruited from military special forces units (Green Berets, SEALs, MARSOC) or tier-one units (Delta Force, DEVGRU) to the CIA Special Activities Division, where they receive further training. What they do day-to-day, outsiders will probably never know.",
"I'm not really sure why so many people are saying that you won't get a good answer. This type of stuff is covered in mid-level political science classes.\n\nELI5 Answer: Spies do stuff that a government wants/needs done but can't admit to doing. For example, they may pay a group of people to protest the leader of a country to possibly start a revolution or mass protests. They may also try to gather human assets, meaning people who have access to sensitive information and would be willing to pass it on to another party.\n\nAdult Answer: If you research the CIA's role in the 1953 Iranian coup, the Iran-Contra affair or how they supplied weapons to the rebels in Afghanistan, you will have a very good idea of what spies do or at least what the covert operations unit of the CIA has done.",
"Bullshit on people saying you can't know. [Here](_URL_0_) is a textbook for how espionage works that is pretty much required reading for graduate level international studies and should be read by anyone serving in federal public office.\n\nSpying does not work like in James Bond. Every country does espionage a little differently. The US and UK intelligence agencies follow the same model (because the US copied the British after their intelligence success in WWII). The KGB was similarly modeled, except they also did heavy domestic spying and secret police work. Its successor, the SVR is closer to how the CIA operates. Mossad took the US/UK model and went a bit of a different way. Mossad actually are a bit similar to James Bond in that their officers do some of the ground work.\n\nAnyway, here's the basics of HUMINT (Human Intelligence, i.e. the interesting stuff that people get paranoid about). There are two classes of people in espionage that often get confused in the Hollywood mythology of \"spies\". There are officers of the intelligence agency and there are agents. Agents are not directly employees of the intelligence agency, they are citizens of the country that is being spied on who for some reason or another are willing to commit treason by giving up sensitive data. Officers are people who are actually hired by CIA, MI6, etc. Their job is to make contact with current agents to retrieve collected data and research people who could possibly be used as agents and give them a pitch. Here's how pitches work, an officer receives an order from HQ that they need information on something. He researches people that could possibly have access to that information and can either be blackmailed, paid off, threatened, or sometimes just talked into it. People targeted are often either sociopaths, desperate, or ideologically inclined to betray their country or organization. Depending on the type of pitch, they find a way to secretly get in contact with the potential agent and convince them to collect information or do other tasks such as disinformation or sabotage for them. It almost never happens that a pitch is declined because pitches are only made after they are absolutely sure the potential agent fits the model for an informant (the threat of retribution by both the officer and the contact's home government also helps). After the agent is \"recruited\", the officer makes frequent contact with them both to convey collected information and orders, and to keep them in line. Intelligence officers often work a cover job (usually at a diplomatic outpost such as an embassy or consulate if at all possible, so they have a degree of diplomatic immunity if they are exposed). The collected information gets sent back to the intelligence agency for analysts to do their magic.\n\nThere is several other types of intelligence such as SIGINT (Signals Intelligence), which is just monitoring electronic traffic such as radio, internet, etc.; OSINT (Open Source Intelligence), which is basically watching the news with an educated eye; and GEOINT (Geospatial Intelligence), which is taking pictures with spy satellites. These types of intelligence can be pretty much directly accessed by analysts and don't require the massive human infrastructure that HUMINT does.\n\nGadgets aren't really a thing anymore, since a good hacker can do a lot more than James Bond ever could. The use of gadgets is pretty much limited to creative ways to covertly monitor communication. Nowadays, you'll probably see this kind of tech on \"Maker\" blogs like [HackADay](_URL_1_) before intelligence agencies start using it.\n\nEvery country does this to some extent, though some smaller NATO members basically trust what CIA, MI6, and BND (German Intelligence) give them.",
"I knew an old retired CIA employee. He always said it was pretty boring on his end. No guns, no flashy cars, no gadgets. He just read lots of newspapers, took pictures of emabssies and such, and would occasionally pick someone up and bring them back to the USA. He didn't even know who they were most of the time and never saw them again. The only time he ever fired a gun was at a gun range. This would've been during the cold war. He was pretty vague about things though, so who really knows what happened. Its a little bit of a let-down to hear that.",
"If anyone London-based is interested, the [Imperial War Museum has a interesting section about espionage, titled The Secret War](_URL_0_). It features original gadgets used by actual spies during the WWII era and the cold war.\n\nIt was pretty impressive when I went to see it. The London IWM is undergoing a remodeling process now, though, so their opening times might be very limited.",
"Why would Helen Keller need to know?",
"We are the dead.\n",
"In terms of the CIA, I think they're most commonly known as case officers. They are part of what is know as the [National Clandestine Service](_URL_0_) (NCS). The website lacks details pretty hard (obviously), but basically they operate around the world while carrying out all the secret stuff you and I don't know about. These individuals deal in HUMINT, or human intelligence. HUMINT is any information gathered from human sources. This could include names or addresses; enemy movements; personality information, likes, and dislikes of persons of interest; or any other pertinent info to the mission at hand.\n\nYou apply to be one of these individuals much like any other job. The US government uses a website called _URL_1_ for all positions in the government from the guy who mops floors at the Yosemite National Park welcome center to the national security analyst in Washington, DC. On this website, you'll be screened for qualifications, language/area experience, education, previous employment, etc. These positions (I can assume) aren't the type of things you do right out of college. I'd bet you'd have to get in on a recommendation from someone within the intelligence community as well. Lots of members of the NCS are existing intelligence officers or former military.\n\nIn terms of tech, no one really knows. Back in the cold war, however, many ingenious devices were invented. Umbrellas that shot a pellet of poison out the tip. Cameras that concealed code breakers. Secret compartments in everyday items. Fake teeth filled with cyanide and other \"last resort\" options. The museum at CIA headquarters in Langley showcases much of the equipment used for intelligence gathering since WWII.\n\nSOURCE: In college, I took a class on the intelligence community. We had the opportunity to speak to many members of various governmental intelligence organizations and took a trip to CIA headquarters in Langley.\n\n",
"In New Zealand you can just [go to the website](_URL_0_). The GCSB (think NSA) has a similar part on [their website](_URL_1_). I've also seen the GCSB at university career days advertising for maths, comp sci, electrical engineers, and physicists. The other way in is through doing something like intelligence or signals in the Defence Force and moving through from there.",
"My grandfather passed away years ago, but my grandma loves telling this story: He was the ambassador to India - In the 80s, this was during the time that there was a lot of controversy about the KGB and the CIA paying off governments, especially in Africa, and installing puppet regimes.\n\nMy grand-dad would host tons of formal parties, and after they were done, he and his buddy - the ambassador of Ghana - would sit around and polish off the good booze late into the night. Inevitably, the ambassador from Ghana would get piss drunk, stand up, hold out his palms into the world, and loudly complain, \"My left hand is open for the KGB, my right hand is open for the CIA, but both are empty!\"-- mostly joking, I'm sure ;)",
"With all respect to /u/AlienJunkie this isn't the complete story.\n\nMi familia worked for the CIA and military counter-intel and they've told me some interesting information.\n\nThere are two branches of intelligence gathering: human intelligence (humint) and signals intelligence (sigint). Signals intel is what we usually hear about: things like the NSA tapping phones, etc. Human intelligence is what we normally think about when we talk about spies. The US intelligence community has in the last few decades reduced its reliance on humint, which occasionally bit us in the butt and in the Middle East we have had to rely on French, British, and Israeli spy networks.\n\nSo, how does this humint stuff work and what do they do?\n\n* Maintain contacts: usually they have a group of individuals that are civilians, but are closely tied to other governments or important individuals, with whom they maintain cordial relations. Often these individuals are aware that these \"friends\" are spies. These contacts may be selling documents for money or may just be acting as tourists in another country. (I knew a guy who ran a spy \"ring\" that maintained contacts with Solidarity by working with Poles wealthy enough to travel)\n* Infiltrate: spies will either go in under fake identities and try to pass themselves off as citizens of another country and get important jobs and report on those jobs back home. That *rarely* works. In fact, some regarded that sort of job as a death sentence and it is very rare that the US creates an identity whole clothe and uses him or her to infiltrate a nation-state (a group without data infrastructure is different). Usually spies use their contacts to gain information about groups, etc. Occasionally they will turn an enemy agent or an enemy individual and use that person to plant information or steal things.\n* Exfiltrate: spies often have to smuggle out people who know important things. Usually individual knowledge is more useful (because it's more contextualized) than a database dump. During the Cold War the US would often help Eastern Europeans take a trip to East Germany and sneak them into West Berlin.\n* Trailing/Watching: They often have to just follow people, learn their habits, their interests, etc. They usually do this before they make contact with an individual. They either try to understand a potential contact's personality better or they're looking for leverage on the contact. (Back in the day CIA agents may have exploited a Soviet embassy staffer's hidden homosexuality and used the information to turn him)\n\nThe training required for this is very specialized. During the 1980s spies learned things like how to flick coins or folded up pieces of paper into a tree stump (seriously-- back when people littered out of their cars it was a great way to communicate). They were also tortured. Basically, they were forced to undergo all of the tortures you hear about on the news: water boarding, hot boxing, standing for hours, sleep deprivation, etc. Furthermore, they learn how to do things like study body language so that they could \"read\" their contacts.\n\nAs for how they're recruited ... well, you often apply. If you are smart and clean, then you may make the grade.\n\nAnd as for gadgets, it's usually not as sexy as anything James Bond would have, but it's often quite [inventive](_URL_0_).",
"If they're good at their job, we'll never know.",
"The first thing we learn is that ██████████████████████ combined with █████████████████ ██████ makes a complete piece of the ██████████████ that would ██████ ██████ ████████████████ when Obama ████████████████████████ the top 10 way would most likely █████████████████████ and ████████████████████ hope that helps ████████████ .",
"I suggest you read \"See No Evil\" by Robert Baer. An ex-USAF intel gave me the book, and it was super informative. You'll want to read the first section. The last two are a bit hard to follow, but its still worth reading the entire thing ",
"Some spies are recruited most apply for the job. Spies don't do any actually spying though. All they do is recruit spies from the country they've been assigned to. They will typically have a cover job and do their clandestine work apart from their cover job. They'll look to befriend and 'turn' people in industry, science, military and government jobs. ",
"We don't get anything much in gadgets except for a tiny laser capsule embedded in our backs with some numbers in it, and the endless nightmares that just wont go away. However, I can order coffee in 74 different languages. But i still can't get the 7-11 clerk to understand me.",
"Late response and this will probably never see day light but:\n\n\nThere seems to be a misconception with CIA \"agents\".\nCIA Agents aren't the people that come from the homeland. CIA Officers are recruited (mostly) from the homeland and usually, like Thriftocracy said, have a cover ID which says they work at the embassay with a false agency. If the get caught, they're shipped home. If you've ever seen Zero Dark Thirty, when she's getting shot at outside her home, her cover was blown and she was sent back to Langley to work out of HQ. CIA Officers, aka \"Case Officers\", work for the Directorate of Operations (DO) also now known as the National Clandestine Service (NCS). \n\nCIA Agents are contractors that work under a CIA Case Officer. They're the people that physically gather evidence and work for a foreign government, or close to someone who has access to secrets or noteworthy intelligence. They meet with a case officer, sometimes using a \"dead drop\" or actually meet with the CO. \n\nOfficers are recruited from all sorts of backgrounds. With or without military experience. the NCS has a program that recruits mostly 21-25 year olds and trains them for cladenstine work, the only requirement being a Bachelors degree and 3.0 GPA. \n\nHowever, the CIA is now a shadow of what it was during the cold war unfortunetly. It got to the point where the Army actually made their own intelligence 'agency' because they were getting no help from the CIA (Intelligence Support Activity). The CIA has gotten further from HUMINT (Human Intelligence) and closer to SIGINT (Signal Intelligence, basically computers) which is a huge problem. The CIA has become more bureucratic and CO's are having a hard time because they're being commanded by people who sat behind a desk their whole life instead of actually working in the field. Still, the CIA and intelligence community as a whole are very necessary in counter terrorism and their value is unmeasurable. \n\nI recommend reading \"See no Evil\" by Robert Baer, it's fantastic and gives a very accurate dipiction of how the agency works.\n\nSource: That's Classified "
]
}
|
[] |
[
"http://www.reddit.com/r/explainlikeimfive/comments/1gv6tl/eli5_what_do_real_spies_do_how_are_they_recruited/cao8qcr",
"http://www.reddit.com/r/explainlikeimfive/comments/1gv6tl/eli5_what_do_real_spies_do_how_are_they_recruited/cao6lks"
] |
[
[],
[],
[],
[],
[],
[
"http://www.gq.com/news-politics/newsmakers/201206/my-father-and-me-spy-story-russia"
],
[],
[],
[],
[],
[
"http://www.stuffyoushouldknow.com/podcasts/spies-work/"
],
[
"http://en.wikipedia.org/wiki/Human_intelligence_(intelligence_collection\\)",
"http://en.wikipedia.org/wiki/Clandestine_HUMINT_operational_techniques",
"http://en.wikipedia.org/wiki/Numbers_station",
"http://en.wikipedia.org/wiki/Clandestine_HUMINT"
],
[
"https://www.mi5.gov.uk/careers/current-jobs/job.aspx?id=184"
],
[],
[],
[
"https://www.cia.gov/careers/opportunities/clandestine/view-jobs.html"
],
[
"http://www.amazon.com/Chinas-Exploding-Powers-Unmasking-Strategy/dp/0984078207"
],
[],
[
"http://www.amazon.com/Confidential-Business-Secrets-Getting-Keeping/dp/097213560X/ref=sr_1_1?ie=UTF8&qid=1371935642&sr=8-1&keywords=john+nolan"
],
[],
[],
[],
[
"http://www.blowingmycover.com/",
"http://en.wikipedia.org/wiki/Lindsay_Moran"
],
[
"http://en.wikipedia.org/wiki/Special_Activities_Division"
],
[],
[],
[],
[],
[
"http://www.amazon.com/Intelligence-From-Secrets-Policy-Edition/dp/1608716759",
"http://hackaday.com/"
],
[],
[
"http://www.iwm.org.uk/exhibitions/iwm-london/secret-war"
],
[],
[],
[
"https://www.cia.gov/offices-of-cia/clandestine-service/",
"USAJobs.com"
],
[
"http://www.security.govt.nz/careers/",
"http://www.gcsb.govt.nz/careers/current-vacancies.html"
],
[],
[
"https://en.wikipedia.org/wiki/Thing_%28listening_device%29"
],
[],
[],
[],
[],
[],
[]
] |
|
z9txe
|
i'm curious, why don't humans just 'taste' unhealthy food? why do we have to swallow it?
|
I've been thinking about this for a long time; Why don't we just taste unhealthy food (like cake, candy etc) and then spit it out? Why do we have to swallow it in order to enjoy it?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/z9txe/im_curious_why_dont_humans_just_taste_unhealthy/
|
{
"a_id": [
"c62qmi4",
"c62rvxq"
],
"score": [
8,
2
],
"text": [
"Because the part of your brain that controls the feeling of being full (satiety), the [arcuate nucleus](_URL_0_), probably wouldn't be stimulated.\n\nAlso, it's not that those foods themselves are intrinsically unhealthy. If you're on a desert island or, a human who sucks at hunting mammoth, those foods would be perfectly \"healthy\" in that they are calorie dense and will help you survive. That is one reason why we like those foods so much. The problem is that obtaining calorie dense foods has never been easier, yet we can't turn off the biological switch that makes us like calorie dense fats and things like salt (which is absolutely necessary for human/animal survival and wasn't always as easy to obtain... i.e., the term salary derives from Latin word for salt).\n\nTl;dr: the part of the brain that makes you feel full wouldn't be stimulated and so you wouldn't enjoy it as much. The enjoyment of such foods is biologically inherent.",
"What about bubble gum?"
]
}
|
[] |
[] |
[
[
"http://en.wikipedia.org/wiki/Arcuate_nucleus"
],
[]
] |
|
9rh39j
|
how do executives hold board of director positions at multiple fortune 500 companies?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/9rh39j/eli5_how_do_executives_hold_board_of_director/
|
{
"a_id": [
"e8gvoyp",
"e8gw1tv"
],
"score": [
5,
2
],
"text": [
"The Board only meets occasionally to vote on more important matters. They don't really deal with day to day affairs like the CEO does.",
" > I thought being executive/ CEO was a lot of work how can somebody possibly be in charge of all these companies?\n\nBoard members are not usually executives. The executives will serve on the board but most board members will be experienced business leaders from other companies who can help plan the future of the company. The board deals with very big picture and strategic planning, they have no day to day responsibilities"
]
}
|
[] |
[] |
[
[],
[]
] |
||
8c8fvm
|
Why is the popular view in Western pop culture that the German army fought a "clean war" on the Eastern Front of WWII, independent of the genocidal policies of the Nazi regime? How did a romantic view of the German army on the Eastern Front become mainstream?
|
In Western popular culture (books, video games, etc.) the German Wehrmacht is often presented as the embodiment of courage, honor, and self-sacrifice, even though they were complicit in many war crimes on the Eastern Front (the Commissar Order, assisting the Einsatzgruppen). How did the "Clean Wehrmacht" myth get promoted and why has it seemingly been so successful?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/8c8fvm/why_is_the_popular_view_in_western_pop_culture/
|
{
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"dxd0pth",
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12
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"text": [
"From an [older answer](_URL_0_) where /u/Georgy_K_Zhukov also weighed in on the subject matter:\n\nThe clean Wehrmacht myth was something that was advanced by both the (West)German and the Western Allied governments after the war within the context of the budding Cold War. There was it's own Eastern German version of it but since the Western narrative is far more influential, I'll focus on that.\n\nIn the immediate aftermath of the war, Allied denazification of Germany was a thing taken rather seriously by the Allied governments. While every Western Allied government acted slightly different in their occupation zone and the Soviets focused on those who had committed crimes against the Soviet, almost 200.000 Germans had been arrested by the Allies in the immediate aftermath of the war and rather harsh laws instituted. While only a certain percentage (about 85.000) of those arrested were sentenced, when it became clear that there was to be a German state again in the running up to 1949, what was to become the German government under Konrad Adenauer took up the case of those arrested and sentenced for Nazi activity. They mounted a campaign against \"winner's justice\" and \"collective guilt\" to reject them and portray the whole thing as unfair.\n\nThe Wehrmacht as an organization in which millions of Germans had fought for the aims of the Nazi state was a perfect case for them. And the man they turned to in order to turn wash the Wehrmacht clean was Franz Halder, former head of the General Staff of the Army. Halder who had been massively involved in formulating the Commissar's Order for the Soviet Union (the document on whose basis the Einsatzgruppen and Wehrmacht shot millions of Jews and people suspected of Bolshevism), was arrested in connection with the July 1944 plot and had been imprisoned in the Flossenbürg Concentration Camp when the Allies liberated him. \n\nDuring his time in Allied captivity, he had declared to be willing to help the Allies and was made part of the war historical study group of the US army's Operational History (German) Section. This section was charged with producing an account of the Wehrmacht's involvement in the Nazi state and its crimes. Halder and his colleagues had access to a lot of the captured German material and they set to work to produce an account that portrayed the Wehrmacht leadership as a tool abused by the Nazi state but far from implicit in its crimes. Several historians posit that it was Halder's aim to in essence portray the majority of the Wehrmacht leadership as the unfortunate victims of Hitler. Halder's and his colleagues' plan insofar played into Allied interests since in connection to Nuremberg, there was great reluctance on the parts of some involved to declare the German army or the leadership of the German army a criminal organization per se. While there were cases against the High Command, especially in connection with the hostage policy, the Wehrmacht itself was not declared criminal per se.\n\nThe newly created Adenauer government seized on this fact in 1949 and used to their great advantage with the German population. As I wrote above, millions of Germans had been part of the Wehrmacht and nobody likes to see themselves as criminal so this idea of the Wehrmacht as an apolitical tool full of people who had just done their duty and nothing wrong hit all the right chords.\n\nThe whole narrative really got the propagandist push it needed when early on it the German Federal Republic's existence, the question of an army was raised. With the war in Korea escalating, the Western Allies sought to rearm Germany in order to have another ally in Europe against the thread of Soviet invasion. In 1950 the Adenauer government and the Western Allies began secret talks about German rearmament.\n\nFor these talks, Adenauer conveyed a panel of former Wehrmacht officers, many of them implicated in the July 20 plot but also including notable war criminal Adolf Heusinger, in order to formulate a policy of German rearmament. The document they produced was the Himmeroder memorandum, in which the conditions for and the form of the future German army was laid out from their perspective.\n\nThe first part of the Himmeroder Memorandum includes the political, psychological and military conditions for German rearmament. The Adenauer government claimed it essential that the Western Allies stop the \"defamation\" of the Wehrmacht, Waffen-SS and its members, that all members of the armed forces sentenced for war crimes be released, and that all acknowledge that they acted in accordance with orders and the German law of the time.\n\nWhile it took some time until the Allies agreed to these provisions (and they didn't agree to all of them), this was to massively shape German policy vis a vis the Wehrmacht for years to come. Soon after this, the Adenauer government founded several study groups consisting of former Wehrmacht members that were to influence how the history of the Wehrmacht was written in German academia and whose job it was to get former important Wehrmacht members to write revisionist autobiographies pushing the clean Wehrmacht narrative. And while the Allies acquiesced somewhat when it came to stop \"defaming\" the Wehrmacht, in Germany, this policy was hugely successful.\n\nPretty much every book of a former Wehrmacht general was written as part of this effort. All the shitty autobiographies people for some reason still read, from Panzerleader to *Aus einem Soldatenleben* etc. All these were part of a concentrated effort by the German government to exonerate the Wehrmacht and its leaders.\n\nSo, when asking about the clean Wehrmacht myth, there is a certain from below social dynamic to it when it comes to millions of former members but one also needs to remember that part of it came from a concentrated German government effort to paint the Wehrmacht in a positive light that did within the context of rearmament receive help from the former Western Allies.\n\nIt is also important to note that all these books still in circulation, whether by Guderian, Manstein or others, were written by literal shills for clean Wehrmacht.\n\nIt took until the 80s and 90s to fight and root out this narrative from German society and some parts of it like Rommel are still around despite the fact that the historical circumstances have changed so greatly. But all this makes me plant my feet firmly in the camp that people still pushing clean Wehrmacht either have a rather nefarious political agenda or have not delved deeply enough into the historical material to make any kind of informed claim on the matter.\n\nSources:\n\n* Klaus Naumann: Die „saubere“ Wehrmacht. Gesellschaftsgeschichte einer Legende. In: Mittelweg 36 7, 1998, Heft 4, S. 8–18.\n\n* Omer Bartov: Hitler's Army.\n\n* Detlev Bald, Johannes Klotz, Wolfram Wette: Mythos Wehrmacht. Nachkriegsdebatten und Traditionspflege.\n\n* Wette, Wolfram (2007). The Wehrmacht: History, Myth, Reality.\n\n* Shepherd, Ben (June 2009). \"The Clean Wehrmacht, the War of Extermination, and Beyond\". War in History. 52 (2): 455–473.",
"The reasons are manifold, but the prosecution of war criminals in general and the Nuremberg trials in particular play a major role. In the main trial of Nuremberg, besides some of the main Nazi leaders (such as Göring, Heß and others) certain institutions were also on trial: SD, SS, Gestapo, the Hitler cabinet and the Wehrmacht. The Wehrmacht, however, was not determined by the judges to be a \"criminal organisation\". Unlike the SS for instance, that meant that solely being a member of that organisation was considered a crime. The original idea was to have a separate trial concerning the Wehrmacht and the crimes committed by members of the Wehrmacht. Such trial never took place for lack of funding and staff, as the allied prosecution lost steam after the main trial at Nuremberg.\n\nIn fact, after the Nuremberg trial, a separate trial was undertaken against the Einsatzgruppen, and some of the officers responsible were sentenced. But here comes the real problem with all post-war trials: People and institutions were tried on behalf of tens of thousands of others, who had commited the crimes. Often, officers, department leaders or political figures were arrested and tried, but many of the men who had their finger on the trigger just returned home as \"ordinary men\". When the big names were convicted, many aussmed that stood in for everyone else, thus clearing then from any crimes.\n\nAnd there comes the third problem: Many of the big names in Nuremberg and later trials based their defence on a notion of duty, carrying out orders and generally being just a little wheel in a big machine. Even Göring attempted to convince the judges that he had no idea of what was happening in the east, many others followed suit. Such language carried on and eventually people just believed it because it was repeated long enough.\n\nLastly, as Germany needed to rebuild and be rebuilt and as the western allies needed a reliable ally against communism many issues were simply brushed under the carpet.\n\nFor those who read German, I highly recommend a brief history of the \"Nürnberger Prozesse\" by Anette Weinke.\n\nMNT is the de-facto standard collection on the Nuremberg trials, but many others exist, including many on the reception of the trials in the German and international public. I am only familiar with German titles, will post if requested."
]
}
|
[] |
[] |
[
[
"https://www.reddit.com/r/AskHistorians/comments/5799li/did_the_rommel_myth_and_clean_wehrmacht_myth_and/"
],
[]
] |
|
rfory
|
How do I hear music in white noise?
|
I sleep with the ceiling fan and a loud stand-up fan to keep my noisy neighbors from waking me up. But as I'm falling asleep, I sometimes hear a faint, unrecognizable song. It wakes me up and then I can't hear it anymore. Is there any cause for this?
|
askscience
|
http://www.reddit.com/r/askscience/comments/rfory/how_do_i_hear_music_in_white_noise/
|
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"White noise contains thousands of different frequencies. Your mind can subconsciously focus on certain frequencies, sometimes making up what you perceive as tunes. Also, take a look at [auditory hallucination](_URL_0_). ",
"This may sound nitpicky but I feel that is one of the tenets of this subreddit! What you are describing is not white noise. It is probably closer to pink or red noise (but more likely not \"noise\" at all. it's most likely more 'signal' than 'noise'). I only say this because if you start doing some personal research into the issue, it may lead you down the wrong path.\n\nIf it truly IS white noise, then you should do some science for us and try to sleep with actual white/pink noise playing in headphones and see if you hear the same 'song'",
"White noise can be many different frequencies. I've had my speakers pick-up white noise and faintly play RF signals from local radio use in the area. Sometimes even phone calls can interfere with another if the other set of people are on a similar frequency as you. The reason i'd think you don't hear it upon waking up is because its so faint and you are no longer subconciously focusing on the song. I had to try really hard to hear the radio.",
"Audiology graduate student here: Our auditory systems are able to perceive pitch and loudness due to a transduction process inside our cochlea (basically the nerve for hearing). After the sound signal has been changed into an electrical signal (inside the cochlea) that can be perceived by our central auditory nervous system (CANS), the CANS can recognize modulation of this auditory input. With little electrical knowledge, I would assume the fan is slowing down at some point in its cycle and then returning back its normal speed. Even though this is white noise, the brain can perceive that fluctuation.\n\ntl;dr the brain can perceive fluctuations in an auditory signal, even if the signal itself is white noise\n\nEdit: corrections"
]
}
|
[] |
[] |
[
[
"http://en.wikipedia.org/wiki/Auditory_hallucination"
],
[],
[],
[]
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|
cyywzl
|
Can Solar Panels be charged with Nuclear Radiation?
|
Or is it possible to create equivalent panels which can? Sort of like "nuclear panels"?
If so, can they exist now?
Wouldn't it be more effecient utility of nuclear energy than boiling water?
|
askscience
|
https://www.reddit.com/r/askscience/comments/cyywzl/can_solar_panels_be_charged_with_nuclear_radiation/
|
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"You can use the decay heat to produce electricity - [radioisotope thermoelectric generators](_URL_0_) (RTGs) do that.\n\nFor beta decays you can directly use the radiation and let the electrons fly through a potential difference - [betavoltaics](_URL_1_).\n\nYou could in principle let ionizing radiation pass through a material that emits light, and then use the light in a solar cell, but that would be really inefficient.\n\nFor nuclear reactors the fission produces fast particles somewhere deep inside the reactor - you can't avoid that getting converted to heat, and then your efficiency depends on how well you convert that heat to electricity. Boiling water is very good in that aspect. There are some ideas for alternative reactor geometries but they exist only on paper as far as I know, and they all come with major downsides."
]
}
|
[] |
[] |
[
[
"https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator",
"https://en.wikipedia.org/wiki/Betavoltaics"
]
] |
|
5niw3q
|
How can something be "10,000 times colder than the vacuum of space"?
|
askscience
|
https://www.reddit.com/r/askscience/comments/5niw3q/how_can_something_be_10000_times_colder_than_the/
|
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"text": [
"A true vacuum doesn't have a meaningful temperature, but when they say \"the vacuum of space\", they are probably referring to the cosmic microwave background radiation, which has a temperature of about 2.7 Kelvin."
]
}
|
[] |
[] |
[
[]
] |
||
2yqan7
|
how does the united states pay for its' wars?
|
The cost of War in Afghanistan has costed 791 Billion and counting so far. I've served overseas for over 2 years of my total life and still don't understand how we can amount such debt. The cost of war is expensive, any war at that matter; and I want to know how we find money to keep on paying for it.
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/2yqan7/eli5_how_does_the_united_states_pay_for_its_wars/
|
{
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"text": [
"Taxes. The US federal government gets over $3 trillion a year.",
"The government does a lot of things that it doesn't have the money to pay for. So, it either takes on debt or prints more money, which is why we have inflation. The only other options are to raise taxes or cut spending, which is a political minefield."
]
}
|
[] |
[] |
[
[],
[]
] |
|
8k8ef4
|
why don’t tornadoes develop in extremely urban areas with skyscrapers such as new york city or chicago?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/8k8ef4/eli5_why_dont_tornadoes_develop_in_extremely/
|
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"_URL_0_\n\n\nBasically not alot of major cities lie in tornado zones so its already unlikely ",
"They do. There just aren't a lot of dense tall cities like you are picturing where tornadoes are common. OKC has been hit several times by tornadoes as have many other cities that are in Tornado Alley.",
"It is to my understanding, that tornadoes start on their sides, circulating faster and faster until they right themselves up. The subsequent funnel is formed as the two ends pick up clouds and ground material, coming to meet in the middle. In order to do this, they need a large, open expanse in which the wind can circulate up to speed uninterrupted. Obviously there’s an exception to every rule, as here in CT, 3 F1s were confirmed. But that’s 3 in however many years, an extremely rare occurrence. To compare, in NE and KS there have been 57 confirmed tornadoes in the month of May alone.",
"In the grand scheme, major cities are actually really small. \n\nThe biggest factor is that these cities just don't really lie in tornado zones. If they do, their land area is still small enough compared to the massive swaths of land around them to make it incredibly unlikely to be hit by a tornado. \n\nOklahoma city was just hit by a big one a few years ago though. (as well as a few smaller ones too)"
]
}
|
[] |
[] |
[
[
"https://www.scientificamerican.com/article/experts-tornadoes-cities/"
],
[],
[],
[]
] |
||
22163k
|
How do we KNOW that a comet, like Halleys, is the same comet each time it comes around (This question from my family after watching Episode 3 of Cosmos) ?
|
Title says it all. My kids and wife asked me this and I don't have a good answer. They are curious how we know that during each orbit of a comet that passes Earth or the Sun that we observe, that it is literally the same comet and not just another on the same or nearly the same orbit.
|
askscience
|
http://www.reddit.com/r/askscience/comments/22163k/how_do_we_know_that_a_comet_like_halleys_is_the/
|
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"Because we can predict their passing in the sky with accuracy (diabolical accuracy might I add)\n\nThat is the power of Newton's mathematics. (Next time your kids ask you what is math good for this is a good example: math can explain and predict basically everything that is going on in the universe) \n\nBy calculating it's trajectory, velocity, orbit, etc... Astronomers can predict, precisely when and exactly where the comet will be back again. \n\nIf they were different objects, they would not appear in the sky at the exact predicted time, in the exact predicted location.",
"Math. \n\nAs has been pointed out Newtons mathematics can be used to calculate trajectory, velocity, and orbit. \n\nThe mathematical concepts are unbelievably accurate. So much so that we can predict when [Venus will transit the sun](_URL_0_) down to the *second*, despite that it happens well over a hundred years apart. ",
"The answers so far have not been satisfying. What if the orbit was perturbed. How do we now that it is still the same comet? IOW, is there anything that permanently and uniquely identify a comet?\n\n",
"We'd have to also explain what happened to the other comets that were on this orbit but seemingly vanished before their next appearance (while also explaining why a new identical comet was able to spontaneously arrive on that orbit since the last time it should have been around and was not seen)",
"When it came by last time, orbital elements such as period, inclination, eccentricity, etc. were calculated to some degree of accuracy. Based on these orbital elements (which do not change very much over the course of one orbital period) it can be predicted almost exactly where and when in the sky this comet will next appear.",
"For one thing, we can observe Halley's comet throughout its entire orbit now.\n\nBut even if we couldn't, the other explanation was that somehow the comet we saw last time disappeared and another, identical comet was placed into the exact same orbit. Clearly that's not a reasonable explanation."
]
}
|
[] |
[] |
[
[],
[
"http://en.wikipedia.org/wiki/Transit_of_Venus"
],
[],
[],
[],
[]
] |
|
vjf1q
|
the legality of the pirate bay
|
I was busy reading their legal threats, and they all seem legitimate... how is the Pirate Bay legal? What was that whole fiasco with the Swedish government trying to take it down?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/vjf1q/eli5_the_legality_of_the_pirate_bay/
|
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"The basic moral/legal question is if a technology that makes committing a crime easy can be held liable for that crime. TPB doesn't commit any crimes, but they enable others to do so. An offline allegory would be an inventor of perfect lockpicks that could open any lock. Would he be at least partially responsible for the crimes committed by his customers? This is an area of law that can go both ways. We don't hold breweries responsible for drunk driver-caused accidents, but we do punish bars that over serve. The question then is where in the chain of responsibility does TPB lie?",
"The Pirate Bay is just a search engine for torrents. In the same that Google is a search engine for, well, everything.\n\nIf you find illegal material on Google, who's to blame? Google or the person who put it up there and made it public in the first place?\n\nHowever, yes, truth be told, TPB is mainly used for illegal torrents.",
"I wouldn't steal a car, but I would download one if I could.\n\nEDIT: The Swedish Government wouldnt take the server down.\n2/3 of the Swedish people (including me) download torrents all the time, and we have a party called the Pirate Party, which allows us to download legally here in Sweden, so its the people who control the Government in this case. You may have noticed that ThepirateBay, changed from .org to .SE because its a swedish server, so the US cant do a shit about it."
]
}
|
[] |
[] |
[
[],
[],
[]
] |
|
84z3ag
|
Why don't electrons all fly off their orbits considering how much energy is present in everyday contexts?
|
I'm looking in class at how much energy is required to send an electron to the next orbital (for only Hydrogen right now!) but I could not get an explanation as to why the electron's tangential velocity would not be great enough to cause it to go somewhere else (considering most energies we deal with are to the -19th degree (is that a proper way of saying 10^-19 ?)).
|
askscience
|
https://www.reddit.com/r/askscience/comments/84z3ag/why_dont_electrons_all_fly_off_their_orbits/
|
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"What grade are you in where this topic has come up? The abstraction of the electron as an actual particle making circular orbits around the atom's nucleus is a poor and inaccurate model that can not be used to meaningfully answer this question. At the scale we are talking about, you shouldn't use the math of Newtonian physics like that to discuss an electron's \"velocity\". The Schrodinger equation and other tools from quantum mechanics are more appropriate for describing the energies involved.",
"For a hydrogen atom, the energy levels of bound states relative to a free electron at rest are -13.6 eV/n^2 where n=1, 2, 3... are the different shells. As you can see just from the formula, all these values are negative. They have to be: If you give an electron more energy than it needs to escape, it will escape and not be in a bound state. The energy that is sufficient to get from one state to another cannot make the electron escape by definition.\n\nThe \"velocity of the electrons\" (their kinetic energy) is taken into account in these energy levels.",
"Electrons don't actually orbit the nucleus like little balls; that's the classical interpretation, but it isn't even close to being accurate.\n\nThink of it like this: you know that any object which is moving on a circular path is experiencing an acceleration. But any time an electron is accelerated like that, it'd need to account for the change in its trajectory by emitting photons. When we observe the atom, we don't see any photons being emitted. That was one of the nails in the coffin for that interpretation of the atom, because the interpretation required a little ad-on that said \"electrons don't emit when orbiting\", and there was just no physical justification for it. \n\n*[It's similar to how quantum mechanics requires us to artificially invoke the collapse of the wavefunction. It doesn't arise naturally from the mathematics, but the model wouldn't fit observations if it didn't collapse. It's a sign that the theory is not yet complete/understood in some way.]*\n\nRather, electrons can be thought of as potential clouds in space and time since they're small enough for quantum effects to become significant. It's known as the wave-particle duality, and it comes about because the wavelength associated with an object the \"size\" of an electron is about the same size as the electron itself. For larger objects, the wavelength is so incredibly small (think 10^-31 m) that approximations as solid objects work fine. \n\nOr they can be thought of waves, and moving an electron to the next orbital is just changing the wavelength by a quantised amount. Since the beginning and end of the wave needs to meet up in the same place, that limits what waves will fit and where they'll fit. \n\nOf course, none of what I've said is strictly true. Just like your moving ball analogy, they're all inaccurate to some scale and we just pick whichever one applies best to the things we're calculating and the scale we're working at. For most things, you don't need or want the full Schroedinger treatment. "
]
}
|
[] |
[] |
[
[],
[],
[]
] |
|
t1vza
|
The link between The Great War, WWII and the Cold War
|
Hello. I would very much like an explanation of the links between The Great War, WWII and The Cold war. I vaguely remember from my history classes that the reason for the first world war was some sort of murder in serbia? I also remember that the reason for the second world war was that Germany felt that they got screwed at Versailles. Am I correct? I am very history interested, but I am more interested in Ancient Greek and Early Roman history than the history of the past 400 years.
If anyone could help me understand it would be greatly appreciated. Also, cite your sources please - I have heard some pretty vile and stupid stuff about history before....
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/t1vza/the_link_between_the_great_war_wwii_and_the_cold/
|
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"Well you're pretty much correct. For a simplified version, after WWI in Germany, there was the \"stab in the back legend\" in which the Army said that the cause for defeat was politicians at home.\nSince no fighting happened on German soil it was easy to believe.\n\nHitler came to power, started WWII. After WWII the Allies divided up Germany. Soviets got East and the other 3 allies shared west. Berlin (deep in the east) was also divided. \nThe cold war was essentially America trying to stop the spread of communism. Thus the policy of \"containment\" \n\n The Marshall Plan was a way to infuse money into Western Europe and promote Capitalism. \n\nWhen Berlin was cut off from West Germany the Berlin Airlift delivered supplies to West Berliners and turned into a moral victory for Capitalism. \n\nExtremely simplified version.",
"Alright, I'll take this from the top in the most detailed way I can. I feel it unnecessary to cite sources, as I believe most of this is common knowledge, and a quick Google search will prove me right. \n\nSo WWI started because Archduke Franz Ferdinand of Austria-Hungary was assassinated by Gavrilo Princip, a Serbian nationalist. This was the murder in Serbia you mentioned. Now, while this was the inciting moment of the war, it was not the cause of it. If it had merely been the assassination of the archduke, the war would have been fairly localized and likely forgotten. What made it a World War was the complex string of alliances. On one side you had Triple Alliance or Central Powers, which consisted of Germany, Italy, and Austria-Hungary. On the other side, you had the Entente Cordiale, which consisted of France, Great Britain, and the Russian Empire. \n\nThese alliances were caused by imperialism in Europe and the rising power of Germany. No one in Europe really wanted the German state to exist, and it was relatively new, forming only after the Franco-Prussian War in the 1870's. After this war, the Germans took Alsace-Lorraine, a French territory, which built resentment in France against Germany. The two states made alliances, and upheld them. And then we get to Italy.\n\nItaly was also a relatively new state. They accepted Germany's invitation to ally in hopes to obtain lands in France. However, they also wanted Austro-Hungarian lands. This caused a rift between Italy and its allies. The Italians left the Triple Alliance and joined the Entente powers as they were promised more land in the London Pact than with the Central Powers. \n\nThe Ottoman Empire also joined the Central Powers. The Ottomans were known as the \"sick man of Europe\" as they were had been on a steady decline for decades, if not centuries. WWI was the final nail in the coffin, and they were subsequently destroyed by their enemies. Their empire, along with Austria-Hungary ceased to exist after Versailles, which leads into my next point.\n\nThe Treaty of Versailles did inflict harsh punishments on the losers of WWI, but especially Germany. France lost the most, and so took it out on Germany, imposing the \"war guilt clause\", essentially laying blame for the war on Germany, and heavy fines. When the Germans were unable to pay, they printed money, causing hyperinflation. France then took control of parts of their country. This bred resentment towards France in Germany, paving the way for Hitler.\n\nHitler and the Nazis rose based on a model laid down by Mussolini in Italy. He and his black shirted fascists used fear to gain support. They were a gang essentially, beating up political opponents, shutting down newspapers, all that nasty stuff. It was because of poor economic conditions following (and for the Russians, during) WWI that the radicals were able to take power. \n\nThe Nazis did the same. They organized riots and staged coups, such as the Beer Hall Putsch. They then made themselves a legitimate party, winning few seats in the Reichstag at first. They started appealing to people, though. Hitler's promises of justice for Versailles, and fixing the economy were very attractive to struggling Germans. The Nazis became a majority party. Eventually, in an effort to slow him down and appease him, his opponents elected Hitler chancellor in an ill-fated move. Hitler then seized the opportunity presented by the Reichstag Fire to taken complete control of Germany, suspending many personal freedoms. When the president died, Hitler took full power over Germany, becoming the Fuhrer. \n\nAt this point, Hitler became aggressive. He started violating the Treaty of Versailles by building up his forces in secret. He remilitarized the Rhineland, and assumed control of Austria. He then took the Sudetenland, a German speaking area of Czechoslovakia, before taking the whole country. Then he overstepped his boundaries and invaded Poland, along with the Soviets, causing Britain and France to declare war on him. Next, Hitler invaded Denmark, then Norway, then the Netherlands, Belgium and Luxembourg and then France.\n\nHitler exacted his revenge on France, taking Paris in 1940. This caused the country to surrender, however resistance continued for the duration of the war. Eventually, Hitler invaded the Soviet Union. This caused the USSR, the US, and the UK to unite against Nazi Germany. \n\nOnce the Germans were defeated in 1945, attention was quickly turned to the former US ally, the communist USSR. They were considered a huge threat. Thus begins the Cold War, a 44 year long struggle between Communists and non-Communists (not necessarily capitalists). And that's how the three are related."
]
}
|
[] |
[] |
[
[],
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|
96krqz
|
how do boxtops fund education?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/96krqz/eli5_how_do_boxtops_fund_education/
|
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"School collects box tops & sends them to the company. The company sends the school money.\n\nThe idea is that people will buy more products from the company if they know it'll help the local schools. It's just an advertising campaign.",
"Basically when you purchase a product with the \"boxtops for education\" and send it to the school when it is scanned the company knows which product was purchased, and how much profit the company made from the sale of that product. From that information a percentage of the total profits made towards the materials from which the boxtops were gathered is donated towards the school funds from the registered school which receives the boxtops."
]
}
|
[] |
[] |
[
[],
[]
] |
||
1i9snv
|
Refining particle collision calculations
|
Historically, people have been building colliders whose speed at collision was higher and higher, to try and see more new particles appear.
It seems now a good portion of the Fundamental Particles has been discovered, and now studies are done to refine the calculated properties of all of these particles.
I wanted to ask if the following was considered:
Approximately many particles are in each "bunch" in the Large Hadron Collider for each collision?
From what I have seen in all colliders, billions of particles are set to collide with each other.
The idea is that if you collide much fewer particles at a time, it is possible they will often be too far away from each other, to fully interact.
Thus, instead of colliding, say 10 or so particles at a time, billions of particles are collided, and each recorded collision is very carefully examined for every single interaction that had occurred.
Accelerating all of particles, as apposed to just 10, requires considerably more energy.
However historically it was more easy to use more particles, rather than to steer them in a more focused path to collide in a more specific location.
Reducing the number of particles, but focusing them better would have a number of benefits:
* Less energy required to accelerate particles to a certain speed. Possibly less equipment is needed to sustain the particles in motion.
* With a smaller more focused collision size, the chance a collision will occur would be much higher. You would get results faster with the same number of collisions done.
* By reducing the number of particles collided, you substantially simplify the recorded information. Analyzing the collision would be much easier, even though these are advanced high speed collisions.
With where we are now, is there any planned development, anywhere in the world, to change focus size to something much smaller so we can reduce the number of particles in each collision?
|
askscience
|
http://www.reddit.com/r/askscience/comments/1i9snv/refining_particle_collision_calculations/
|
{
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"cb2dx3f"
],
"score": [
15
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"text": [
"1. 1.15*10^(11) protons are in each proton bunch ([source 1](_URL_0_))\n\n1. Just because there are hundreds of billions protons, they do not all collide in each bunch crossing. Each bunch crossing will see somewhere between 0 and 30 collisions. If multiple collisions occur, most will be glancing collisions, and in general, there will be one that is by far the most heads-on, and thus converts the most energy to particles.\n\n1. ~~Comparatively, the Tevatron did use fewer particles than the LHC does. RHIC uses fewer particles colliding than the LHC. Beam optics, how tightly the particles can be focused, is a consideration in the design phase, and is optimized. However, there's this thing called Louisville's theorem. The area in position/momentum space occupied by a bunch is constant. If I squeeze the spatial distribution of the beam, nature requires that the range of momentum each particle of the beam has must increase. The momentum is proportional to the energy of the particles, so increasing the spread of momentums has the side effect of increasing the spread of the energies. So if I focus the particles more tightly, I have less control over the energy of the collision. You're also fighting the uncertainty principle. The tighter you localize a given proton, the more spread out the proton's momentum must be, and therefore the more uncertain the collision energy. If you want to be able to do any sort of missing energy search (energy that you know the proton had that doesn't show up in the detector) limits how tightly the protons can be focused.~~ See below\n\n1. I don't think the energetic \"price\" is necessarily linear. I think a lot of the expense for things like keeping magnets supercooled are fixed: the design constraint of the magnet is determined by the design energy at the collision point. So using fewer protons will not actually decrease your magnet cost.\n\n1. The pileup issue (multiple collisions/intersection) would be simplified if the number of collisions were decreased. However, the Tevatron saw about 5 partial collisions per event, the LHC sees like 20-30. However, the scientists involved have figured out ways of filtering out each event, and separating the different results of the various collisions. The primary collision (the most intense interaction) tends to be pretty significantly more interesting than the other interactions. \n\n1. Remember, the frequencies of collision are much faster than the rate at which they can be recorded. Even if each collision were a single square-on collision, we can't write each collision to a computer's memory. There are criteria that the computer looks for in the detector readout that determine which one in a thousand collisions end up getting recorded. The LHC may have 6x as many collisions per interaction, but the scientists have figured out some ways to use that extra data to their advantage."
]
}
|
[] |
[] |
[
[
"http://lhc-machine-outreach.web.cern.ch/lhc-machine-outreach/beam.htm"
]
] |
|
2ctx1w
|
Why is it so difficult to find a map of the papal states?
|
I was trying to find a map of the various papal states in the 1800s, but when I started searching, I found that not only could I not find them, I couldn't find them from ANY time period, or even a list of them! On every map I've found, they're just collectively labelled "Papal States"
What gives?
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/2ctx1w/why_is_it_so_difficult_to_find_a_map_of_the_papal/
|
{
"a_id": [
"cjj1fkn"
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"score": [
6
],
"text": [
"I searched \"papal states map\" on Bing, went to images, and saw one without scrolling. It's an 1847 2nd Edition map, link if you'd like.\n\n_URL_0_ \n\nThey're not individually labelled on the maps because the maps are generally larger scale, and printing the names would be a gigantic hassle.\n\nEdit: I found some other maps, as well.\n\n_URL_2_\n\n_URL_1_"
]
}
|
[] |
[] |
[
[
"http://www.historyguy.com/papal_states_map.gif",
"http://europeanhistory.boisestate.edu/images/maps/Italy1050.jpg",
"http://pages.uoregon.edu/mapplace/EU/EU19%20-%20Italy/Maps/EU19_31%20Development%20of%20the%20Papal%20State.jpg"
]
] |
|
2xfwnz
|
- why do some computer programs let me alt+tab seamlessly to another application, and some will crash or even force me to reboot if i try to use alt+tab?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/2xfwnz/eli5_why_do_some_computer_programs_let_me_alttab/
|
{
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"cozrqat"
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"text": [
"Programs don't receive the command. Alt+Tab is a system interrupt command and is directly interpreted by the operating system without being passed to the programs. Certain full-screen only applications and may not like it much because they are not designed to run in the background, which can cause their graphics or processes to hang when they lose focus.\n\nWithout knowing more about what applications are hanging it's difficult to guess any other reason..."
]
}
|
[] |
[] |
[
[]
] |
||
bh0kvr
|
how can a bank determine fraudulent activity from a single transaction?
|
Especially if that transaction isn't typically out of the normal for the card holder (like being used at a gas station within 100 miles of the card holder's address)?
EDIT: I know this looks like I'm trying to figure out how to steal someone's debit card and not get caught, but I'm asking generally about something that happened to me today. I was told to generalize it as my original question was too specific.
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/bh0kvr/eli5_how_can_a_bank_determine_fraudulent_activity/
|
{
"a_id": [
"elp2rcq"
],
"score": [
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"text": [
"In current day banking it's just machine learning. They fed an AI with a bunch of labeled data, and now it's able to say which transaction is likely fraudulent and which is not; just like the YouTube algorithm showing you stuff you probably want to click on.\n\nNoone knows what exactly the algorithm is thinking, just that it works."
]
}
|
[] |
[] |
[
[]
] |
|
4hgnc7
|
Can modern chemistry produce gold?
|
reading about alchemy and got me wondered.
We can produce diamonds, but can we produce gold?
Edit:^^Oooh ^^I ^^made ^^one ^^with ^^dank ^^question ^^does ^^that ^^count?
|
askscience
|
https://www.reddit.com/r/askscience/comments/4hgnc7/can_modern_chemistry_produce_gold/
|
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"We can, it's just highly, highly impractical. Creating diamond is relatively straightforward, we just have to convert carbon from one form to another. For that all you have to do is to [take cheap graphite, heat it up under high pressures](_URL_2_), and voilà, you get [diamond.](_URL_1_)\n\nCreating gold on the other hand is a different beast altogether since now we have to convert one element into another. Now techniques do exist that allow us to achieve such a transformation using nuclear reactors or particle accelerators, but they are neither easy nor cheap. Probably the most \"practical\" method reported to date was the work of Seaborg and coworkers ([paper](_URL_0_)). Their approach was to take sheets of bismuth, bombard them with high energy ions, and see what came out. Among the mess that resulted, they were able to detect trace amounts of various unstable gold isotopes from the radioactivity they gave off. The researchers also suspected that some of the stable gold isotope (Au-197) was also there, but they couldn't measure it directly. \n\nEven though Seaborg was successful in creating gold, he didn't exactly stumble on a practical industrial process. When asked about the practicality of his work, Seaborg said that given the cost of the experiment, creating a gram of gold would have cost on the order of a quadrillion dollars (in 1980 dollars too!). Needless to say, it still makes far more sense for us just to use the gold that supernovas produced for us than to try to repeat the process ourselves.",
"The big difference between diamonds and gold is that gold is a (somewhat rare) basic element. Diamonds are a specific form of a (very, very common) element: carbon.\n\nWhen you make diamonds, you start with carbon, and arrange it. \n\nIf you were to make gold, you'd have to start with some other basic element and somehow change it gold.\n\nLet's use a Lego analogy:\n\nMaking diamonds is like taking some Lego bricks we already have and building something. \n\nMaking gold is like taking some Lego bricks and turning them into a completely new type of brick that we didn't have before. ",
"The answer of \"yes, via tricky nuclear chemical processes\" is already hit upon, but I'll chip in one thing:\n\nA prevailing hypothesis at the moment is that the vast, vast majority of heavier-than-iron elements are produced solely through the [nucleosynthesis](_URL_0_) of a particular type of supernova; pretty much all the gold (and other heavy elements) we see and use popped out of an exploding star a long, long time ago. Yep, if you're looking at a screen right now, it has spent star-bomb in it.\n\nBy that notion, you're going to have to reproduce some characteristics of a supernova to make gold out of something else--particularly *lots* and *lots* of energy. This is why it's so impractical to produce new elements via artificial fusion: it's absurdly difficult and expensive.\n\n",
"Gold is a chemical element, so if you're making gold out of something that doesn't already have gold in it then, by definition, you're not doing chemistry.\n\nModern **physics**, though, can produce gold from either platinum or mercury.",
"Technically we can. It's just incredibly difficult, and not even remotely cost-effective. \n\nIt would also technically not be considered 'chemistry,' so much as 'nuclear physics,' as it would require the very careful use of nuclear fission reactors. 'Chemistry' pertains to the interactions of elements, so it's sphere of influence is everything from atoms on up. What you're talking about is changing the composition of atoms themselves.",
"Everyone so far has answered the question as you intended it, so I'll be the one to be annoyingly literal. Yes, you can use chemistry (no particle accelerators required) to make metallic gold! Of course, you have to start with a chemical compound that already has gold atoms in it. For example:\n\n_URL_0_",
"IN the 90's I spent a few years routinely making tiny amounts of gold from mercury using neutron activation. One isotope of mercury (Hg-196, 0.15% abundance) can absorb a neutron to become the radioisotope Hg-197 which decays through electron capture into the stable gold isotope Au-197. The Hg-197 decays with a half-life of 2.67 days and gives off a 77.3 keV gamma ray. By counting the number of gamma rays I could determine the amount of mercury in the original sample. Over the full course of the work I made less than 0.1 femtogram (1E-16 gram) of gold.",
"Sure, and there is a TON of gold in the ocean oddly enough that you can collect. The problem is the collection process costs something like 1.2-1.5 cents for every cent of gold you get out of it. But it can very much be done, even on a large industrial scale and is not particularly difficult. We just can't quite make money doing it yet, so no one does it.",
"Others have already answered the question quite well. One thing to note, though is that chemistry only deals with arranging elements into different combinations. Changing one element into another is in the domain of nuclear physics.\n\nSo, modern chemistry can't produce gold and never will. Modern nuclear physics, however, can (though it's incredibly impractical).",
"Gold is an element, which means the substance is defined by the nucleus of each atom. *Chemistry*, as the word is generally used, concerns different combinations of atoms into molecules and mixtures, and as such is primarily about the electrons surrounding a nucleus that allow elements to interact with each other under normal conditions.\n\nTo change an element into another element would require changing the nucleus, and thus involve nuclear physics rather than chemistry. You would need to add or subtract protons, so some process involving fission of a heavier element or fusion of lighter ones.\n\n*Diamond*, on the other hand, is a molecule composed of carbon atoms, and is thus firmly within the domain of chemistry.",
"Chemistry is the study of atomic bonds - how to rearrange atoms. Diamonds are a specific arrangement of carbon atoms.\n\nConversely, gold is an atom itself. Chemistry can't make it because to make gold out of non-gold, you have to change the building blocks that chemistry starts out with, the atoms themselves.\n\nThere is a way to change atoms - it's nuclear physics. Lots of energy can definitely transform one type of atom into another, but it's impractical and expensive (as several other commenters point out)",
"Chemistry, no. This is the realm of nuclear/particle physics.\n\nThe key difference is that diamonds are one form of elemental carbon. Normally you'd find carbon in the form of graphite (sheets of carbon). If you change the structure you could make carbon nano-tubes, bucky-balls (C60) or potentially other exotic structures. If you use sufficiently high temperatures and pressures, you can cause carbon to form diamonds, which are just carbon in a crystal lattice structure.\n\nGold, on the other hand, is an element. To make gold from other elements is similar to being asked to make carbon from hydrogen, for instance. This can only be done via nuclear fusion or fission, depending on whether you are starting with lighter or heavier elements (this is a slight simplification). However, these processes are somewhat difficult to control precisely and very dangerous as they require/release large amounts of energy. The easiest way is by simply bombarding a nearby element such as lead with high energy protons and hoping some stick, but this is hardly precise.\n\nKeep in mind that the way gold is formed \"naturally\" is in stars such as the sun.",
"Speaking of nuclear reactions. The shortest path to gold is unfortunately via platinum. Not much of a value add there (though gold is currently more expensive than platinum). You could do it with enriched mercury-196. A single neutron capture takes you to mercury-197 which will decay by electron capture into gold-197 (the stable isotope). This still isn't practical because the mercury isotope of interest is only 0.15 percent of all natural mercury and handling and enriching mercury would be dangerous and expensive. The largest value add in terms of nuclear transmutation via neutron capture (exempting tritium production and medical isotope prodection) is probably tungsten into rhenium. They are separated by one neutron capture for a pretty big fraction of tungsten. Tungsten is about $20/kg, rhenium is about $3000/kg. You'd also get a little osmium which is about $400/troy ounce.",
"No chemistry can produce gold. Gold a distinct element, which means its atoms have a different numer of protons inside each of them than any other element has. Chemistry doesn't change the proton count, so it can never convert one element into another. In order to turn elements into other elements, you need nuclear physics. We *can* do that, but it's an incredibly expensive way to create gold (like, way more expensive than the value of the gold itself), and has a tendency to give you radioactive gold which is less useful due to being dangerous for humans to handle.\n\nDiamonds are a different issue. There's no 'element of diamond', a diamond is just regular carbon atoms arranged in the right kind of crystal formation. Carbon is already everywhere, trees are full of it, dirt is full of it, your body is full of it. Getting it to stick together into a nice crystal is difficult, but it *can* be done with mere chemistry, you don't need any nuclear reactions.",
"NO. but with modern physics we can get it from sea water. we can use ion implanters to shoot a beam of sea water atoms stripped of their electrons (thus highly positive) then running it thru a magnettic field in a vacuum which deflects charged particles so anything heavier than gold or lighter than gold misses the collector.. in the collector deposited 1 atom at a time would be the gold that is in all sea water. this is not really creating gold tho it is just separating and isolating it.. The refining of gold is a chemical process. To create gold from something else, you need to change the number of protons in an atom.. that's nuclear physics not chemistry. ",
"We could make a few atoms of gold using one of our giant particle accelerators, but it would cost FAR more than the gold is worth.\n\nGold is an element. It is really hard to turn one element into another. Diamond is a particular crystalline form of carbon. Carbon is VERY common. Apply heat and pressure in the right way and you kick the carbon into a diamond.",
"Alchemy is a lot about hermetc philosophy, and turning lead to gold is mostly a metaphor for transmutation of negative/weak/poor thoughts and life experiences into positive. Not that there were not attempts to change lead to gold, and these attempts evolved into modern chemistry and other sciences. Yet the literal interpretation is viewed by most who study alchemy as not the intended meaning. ",
"Diamond is an allotrope of carbon, a different way to order the pure element that results in a material with different traits. Diamond, graphite, and graphene as well as the various fullerenes and nanotubes are all made of pure carbon but have very different properties. \n\nCreating gold, however, is a completely different process. Where changing allotropes of carbon is a physical process, converting something like lead into gold is a nuclear one. It is possible to do, although usually the gold is the result of splitting of much larger atoms or alpha decay, but it strays much closer to the realm of physics rather than chemistry because particle accelerators are necessary.",
"Scientific American wrote about an experiment at Oregon State in the 1980's where they used nuclear reactions to turn lead into gold.\n\nAt that time they calculated the cost of gold created this way at $1,000,000,000,000,000 ($one quadrillion) per ounce.\n\n_URL_0_\n",
"No. Chemistry involves the movement of electrons between atoms. No amount of electron movement can change the number of protons or *neutrons* in the nucleus.\n\nIt is, however, possible to produce gold from other, lighter elements. This falls under the realm of physics, rather than chemistry, because it isn't chemistry. Chemistry is exclusively the movement of electrons. To produce gold from other atoms, you just smash together two atoms that have enough protons to add up to 79 total protons. It's ludicrously expensive and not at all worth the energy costs. Plus, it's usually a radioactive isotope that decays anyways.\n\nSynthetic diamonds are, however, chemistry. What you do is take some carbon and place it under intense pressure and heat until the atoms rearrange themselves (they change which atoms they are sharing electrons with) into the structure of a diamond. The carbon atoms never stop being carbon atoms, they just change which atoms they are sharing electrons with, therefore it's chemistry.\n\nEdit: I have failed as a chemist. Neutrons, not protons!",
"I know this wasn't the question you asked, but even if we could relatively easily create gold via a *nuclear* (not chemical, as others pointed out ) process, the price of gold would change overnight as soon as word got out that you could do this reliably at scale. The moment this was figured out, gold would no longer be a scarce element which would roil the markets.\n\nIf you could do it, it would be imperative to keep it an absolute secret, because as soon as investors found out, they would dump their gold on the market causing the price to plummet. \n\nI'm confident with this talk of astroid mining becoming a reality, that once it becomes clear that there's even a slight chance, say 10% , that an asteroid could be successfully mined, the price of gold would begin to shift.\n",
"Just writing a paper today on nucleur synthesis!\n\nEssentially all elements heavier than iron are only made either in a supernova (R-process), or by other stars using the nuclei from the previous supernovas in a slower S-process.\n\nWe can make some crazy stuff though! Nucleur bomb explosions have yielded rare elements that otherwise don't exist in our solar system. Some elements can be synthesized in labs.",
"First off, diamonds and gold are different things entirely. Gold is an element while diamond is a specific structural arrangement of the element Carbon.\n\nSecondly, chemistry is about the properties of atoms/molecules, how they form bonds with other atoms/molecules, how they react with other atoms/molecules, and all the forces that causes these interactions.\n\nChemistry is not about creating (or transmuting) atoms themselves, which is that you are asking to do with Gold.\n\nSo now we know the difference, making diamond just involves rearranging the carbon atoms from a prior structure to the structure of diamond. \n\nAn element is can be defined by how many protons the atom has. Hydrogen has 1 proton, Helium 2, Gold 79. Making Gold would require adding/removing protons (and neutrons/electrons) from other elements, which is what nuclear physics deals with. Nuclear fission is breaking up larger atoms into smaller ones, and nuclear fusion is combining smaller atoms into larger ones. Since the amount of energy required to fuse two elements together to make Gold is extraordinary, fission is much easier. Fission/fusion would occur in a nuclear reactor.\n\nAlso, we can start off with an element close to gold and bombard it with protons and neutrons in the hope that they 'stick'. This process happens in particle accelerators. \n\nUnfortunately since there is only 1 stable isotope of gold (Au 197) and because it requires giant accelerators/reactors to create, the cost of creating gold is far far higher than it's value.\n\nInformation\n\n* [Chemistry](_URL_2_)\n* [Diamond](_URL_0_)\n* [Gold](_URL_3_)\n* [Synthesis of gold](_URL_1_)",
"Not chemistry really but there are [these bacteria](_URL_0_) that poop 24 karat gold when fed a toxic gold chloride solution, but there *is* already gold present.",
"If we assume you mean produce gold from another substance that doesn't contain any gold then no, chemistry can't produce gold and never will be able to.\n\nAt a very abstract level chemistry deals with interaction of the electrons surrounding an atom. To produce gold you need to start manipulating the nucleus of an atom and for that you need physics.\n\nIf you had asked the question \"Can modern physics produce gold?\" the answer would have been yes.",
"Diamonds are a compound, made entirely of carbon atoms. So is graphite. The only difference between the two is the molecular structure - the pattern of the bonds between the atoms.\n\nGold is an element - the building block from which molecules are made. A single atom of an element is made of electrons whizzing around a nucleus - a cluster of protons and neutrons glued together by gluons. Processes called fusion and fission can change the contents of nuclei and thus change the elements of atoms, but it's difficult and costly. The 'easiest' element to turn into gold is platinum, the next element up."
]
}
|
[] |
[] |
[
[
"http://journals.aps.org/prc/abstract/10.1103/PhysRevC.23.1044",
"http://i.imgur.com/XV8GIUz.jpg",
"http://i.imgur.com/jHQlF1c.jpg"
],
[],
[
"https://en.m.wikipedia.org/wiki/Nucleosynthesis"
],
[],
[],
[
"https://www.youtube.com/watch?v=AHsPkoO4wKw"
],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[
"www.scientificamerican.com/article/fact-or-fiction-lead-can-be-turned-into-gold/"
],
[],
[],
[],
[
"https://en.wikipedia.org/wiki/Diamond",
"https://en.wikipedia.org/wiki/Synthesis_of_precious_metals#Gold",
"https://en.wikipedia.org/wiki/Chemistry",
"https://en.wikipedia.org/wiki/Gold"
],
[
"https://www.washingtonpost.com/blogs/innovations/post/a-bacteria-that-poops-gold-yep-that-exists-and-its-in-an-art-exhibit-video/2012/10/04/1617f178-0e5d-11e2-bd1a-b868e65d57eb_blog.html"
],
[],
[]
] |
|
d4uw5q
|
why is the color red used for the red light district?
|
Do the red lights have any effect on the brain with regards to sex drive?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/d4uw5q/eli5_why_is_the_color_red_used_for_the_red_light/
|
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"text": [
"No. It has to do with old world Asian influences actually iirc.\n\nThe streets with brothels used to use lanterns with red paper to mark the brothels, they were usually all in one part of town so criminal activity would largely be limited to the bars and whore houses and the \"police\" of their respective time periods could more easily contain unruly activity.\n\nThanks to the lanterns these places became called Red Light districts. It stuck.",
"My mother would never carry a red purse or red shoes. She told me that was the sign of a \"loose woman\". Anyway during the depression and up to the 50's she said that was the way it was.",
"I don’t know the answer to the question, but I can tell you that red lights are used in modern brothels because they’re very flattering and hide a lot of blemishes. There’s an element of tradition, but mostly it’s to make everyone look a lil better.",
"There's a story about railroad brakemen needing to carry red lanterns around with them so the train crew could find them in an emergency, and they would get hung in the windows of brothels while they were there, but my cursory research hasn't turned up a lot of evidence for it."
]
}
|
[] |
[] |
[
[],
[],
[],
[]
] |
|
2x5bis
|
when and why did corsets move away from being common place and become more of a sexual statement?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/2x5bis/eli5_when_and_why_did_corsets_move_away_from/
|
{
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"cox48m8"
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"text": [
"Corsets really made some sense in an era of multiple pregnancies; they help hold a woman together, keep the weight of her skirts off her hipbones, and provide excellent back support. The problem arises when the fashion is for tight-lacing that also distorts the back, which was the case in the 1890s. \n\nBut really, the move from corsets is mostly the result of changes in fashion. By the end of WWI, corsets had changed from figure-shapers to figure-smoothers. The 1920s saw the popularization of boyish figures, very short hems,and a new kind of sexualization of women as actors rather than recipients. 1930s corsets were more all-in-one body shapers, and that style continued into the 1940s. Postwar fashions were hyperfeminine, again emphasizing a narrow waist and broad hips and bust - again achieved with corsetry of one sort or another. \n\nWomen still wear corsets, except now they're made of spandex. Frankly, having worn both traditional tight-laced corsets and \"Spanx\" bodyshapers, I'd vote for the comfort of the former every time. "
]
}
|
[] |
[] |
[
[]
] |
||
2p7i0z
|
how were the first people able to access and use iron ore mines to make things?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/2p7i0z/eli5_how_were_the_first_people_able_to_access_and/
|
{
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"text": [
"There is a thing called Bog Iron that is just lying around in bogs. \n\nIt comes from water that has Iron in it and through some chemical processes it turns into a lump of Iron ore.\n\nYou would walk around with a stick poking the ground until you felt something rocky. \n\nYou would also find Iron from meteors."
]
}
|
[] |
[] |
[
[]
] |
||
19532f
|
Otto von Bismarck...man of war or man of peace?
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/19532f/otto_von_bismarckman_of_war_or_man_of_peace/
|
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"text": [
"Can you elaborate on this? I don't understand the question entirely.",
"He was a man of power. Everything he did was to increase Prussia's dominance over Germany and when he unified Germany (without Austria) he ensured that both the nation and the rest of Europe was stable enough to maintain his own power. It was the sudden death of Kaiser Friedrich III and the succession of Wilhelm II that ended his dominance over Germany.",
"There is a problem I have with the answers given until now. They up until now follow totally the \"Bismarck the puppetmaster who set everything up to the Franco-Prussian-War to unite Germany\" reasoning. There are really some points which doesn't fit into that. \n\nBismarck had mostly only one thing in mind, and that was Bismarck, then followed the King, then Prussia - which, one could argue was the same as the King for Bismarck. It's strange that he would go that way he did, given it was very difficult to steal the whole \"unification\"-thing from the hands of the democrats. Before Bismarck, being a nationalist in Germany meant that you would be a liberal and most likely a democrat or a parlamentarian monarchist (look at 1848). \n\nBismarck didn't like war. War was dangerous for him, because he would lose influence on Wilhelm. This goes so far that sometimes the cool kids wouldn't even let him into the war council. He was by no means part of the militaric establishment. The only time he would really be in the military would be 1838, as a Ein-Jahres-Freiwiliger, you would be in the military for a year, then you would be officer of the reserve - a deal nearly everyone who wanted to be someone in Prussia made.\n\nThen there is the problem with the suggested territorial trade between France and Prussia. In short, the French ambassador made a suggestion to Bismarck that Prussia would support France in acquiring Luxemburg and ... maybe Belgium, this isn't clear, and France would support or at least don't mind Prussia uniting the Norddeutscher Bund and the south German states. Unluckily for the ambassador, Bismarck would keep the paper on which the ambassador put the proposal, and publish it in 1870.\nProblem was, the German public viewed Luxemburg as a German country - mostly because some 4 Kaiser of the medieval came from there. So they couldn't go through with that.\n\n\"Blood and Iron\". Nobody knows for sure what Bismarck wanted to do with that speech. \n Either he wanted to reach out to the liberals and nationalists - they thought that Unification could only be archieved through war. Bismarck of course denied that. Or he wanted to scare them. He, of course, denied that also.\n\nWe see, Bismarck simply tried to have every possibility. This, of course was his strengh, but there were some situations where this trying to have all possibilities were quite dangerous for him. The aforementioned suggestion of France could, if the public would not have been prepared, be read as some kind of willingness on his part to make a sly deal with France, which in war would not be popular.\n\nOne of the hardest things, yet, in this Unification, was to persuade Wilhelm to take the crown. In essence, Bismarck had to buy/blackmail the King of Bavaria to send Wilhelm a letter begging for Wilhelm to be Kaiser. Neither Ludwig II., the King of Bavaria, nor Wilhelm liked this. \nAnd there is some evidence that Bismarck didn't really at first realised what the unification meant. In short, it meant the downfall of his own class.\n\nSorry for writing such a wall of text. I think Bismarck is quite interesting and was not as fixed on the Unification or the road to Unification as it appears.\nMy sources are mainly Eberhart Kolb: Bismarck, Otto Pflanze: Bismarck (1 Der Reichsgründer) and Golo Mann: Deutsche Geschichte. "
]
}
|
[] |
[] |
[
[],
[],
[]
] |
||
104jbt
|
the group 'anonymous' and some of the major things they have done.
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/104jbt/eli5_the_group_anonymous_and_some_of_the_major/
|
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"Here you go OP:\n\nAnonymous is a broad term used to refer to members of the 4chan community. (Used in the singular usually as Anon). \n\nThe reason for this came from the posting style of 4chan. 4chan has no registration, so each post is individual. When making a post you had the option of inserting a name if you wanted, however if you did not, the name field defaulted to \"Anonymous\". Hence the term for users of 4chan, specifically of the /b/ community became known as Anonymous. \n\nMajor things they have done? Well there are things they are most well known for. \n\nProject Chanology: Worldwide protests of the church of Scientology in response to the censorship of a church produced video of Tom Cruise. \n\nThe Habbo Raids: Anonymous flooded the online \"hang out\" Habbo Hotel. The members all dressed up their avatars the same way, closed off certain sections of the hotel (pool's closed, pool has AIDS) as well as other offensive and funny interactions with other users. \n\nThe Time 100 Online Poll: the founder of 4chan, moot, was nominated for the Time 100 most influential persons poll. Anonymous put him at the top as well as manipulating every other member of the poll in the top twenty so that the first letters would spell out MARBLECAKEALSOTHEGAME. \n\nMore recently they have been involved in the Dub the Dew \"Hitler did nothing wrong\" contest as well as trying to send Taylor Swift to a school for the deaf to perform a concert. \n\nTo end, here is a very very important distinction. \n\nAnonymous IS: a name used to refer to members of the 4chan community, most often used as a group title when the community decides to do something en masse outside of the website itself. \n\nAnonymous IS MOST CERTAINLY NOT: \n1. A secret club\n2. A \"hacktivist\" organization\n3. An elite group of hackers\n4. Scientology protestors (yes they did this but it is not exclusively what the group does)\n\nHope that helps. "
]
}
|
[] |
[] |
[
[]
] |
||
1w7alc
|
History of Science
|
Welcome to this AMA which today features nine panelists willing and eager to answer your questions on the History of Science.
Our panelists are:
* /u/Claym0re: I focus on ancient mathematics, specifically Egyptian, Greek, Chinese, Babylonian, and the Indus River Valley peoples.
* /u/TheLionHearted: I have read extensively on the history and development of Physics, Astronomy and Mathematics.
* /u/bemonk : I focus on the history of alchemy, astronomy, and can speak some to the history of medicine (up to the early modern period.) I do a podcast on the history of alchemy.
* /u/Aethereus: I am a historian of medicine, specializing in Early Modern Europe. My particular interests center on the transmission of medical knowledge through vernacular texts (most of my work in this field has concerned English dietetic philosophy), and the interaction of European practices/practitioners with the non-European world (for example, Early Modern encounters with India, Persia, and China).
* /u/Owlettt: Popular, political, and social interpretations of the emergent scientific community, 1400-1700, particularly Elizabethan Britain. I can speak to folk belief regarding the emergent sciences (particularly in regard to how Early Modern communities have used science to frame The Other--those who are "outsiders" to the community); the patronage system that early modern natural philosophers depended upon; and the proto-scientific beliefs, practices, and traditions (cabalism and hermeticism, for instance) that their disciplines were comprised of.
* /u/quince23 : I can speak about the impact of science on the broader culture from ~1650-1830, especially in England and France e.g., coffeehouses/popular science, the development of academies, mechanist/materialist philosophy and its impact on the political landscape, changed approaches to agriculture, etc. Although I'm not flaired in it, I can also talk about 20th century astronomy and planetary science.
* /u/restricteddata: I work mostly on the history of nuclear technology, modern physics, the history of eugenics, and Cold War science generally. I have a blog.
* /u/MRMagicAlchemy : Medieval/Renaissance Literature, Science, and Technology. **Due to timezone differences, /u/MRMagicAlchemy will be joining us for an hour today and will resume answering questions in twelve hours time from the start of this AMA.**
* /u/Flubb: I specialise in late medieval science. **/u/Flubb is unexpectedly detained and willl be answering questions sporadically over the next few days**
Let's have your questions!
**Please note**: our panelists are located in different continents and won't all be online at the same time. But they will get to your questions eventually!
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/1w7alc/history_of_science/
|
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"When and why did we start considering science as a field of study distinct from other fields of study?",
"How exactly did Byzantine hospitals operate? Who constructed them/paid for their upkeep, how did they treat patients and who had access to them? What secondary sources are best in order to read further about them? What are the differences between the practice of medicine in the Byzantine world and its practice in the Roman world of the Principate?",
"Was the creation of nuclear weaponry a direct result of the pressures from WWII, or was it simply the natural advancement of weapon technology that would have happened otherwise? ",
"Recently I finished reading Lost to the West: The Forgotten Byzantine Empire by Lars Brownworth. It mentions that Byzantine culture was flourishing even as the empire was falling apart. I assume this would also include science. If so, what would be some examples of scientific achievements from that place and time and how did western world and Ottomans benefited from them? Thanks!",
"I tried this one yesterday [as its own post](_URL_0_), perhaps you can fill in from the perspective of the history of science of antiquity where it overlaps with philosophy: What is the significance of Cicero's [Dream of Scipio](_URL_1_)? ",
"For /u/Claym0re: Do you think that ancient Greek Mathematicians saw themselves as part of an active community of Mathematicians? Did they communicate with one another as part of efforts to advance mathematics? Are there any letters from this era between mathematicians?\n\nAlso, just briefly, do you think that the different mathematical traditions you mentioned (Egyptian, Greek, Chinese, Babylonian, and the Indus River Valley peoples) had very different practical interests involving mathemtics?",
"I'm considering pursuing my masters in history of science. I have just completed my senior research project on Astronomy in Antebellum America. Would any of you have suggestions on how to proceed and what schools (preferably in the Midwest USA) offer good programs in the field?",
"This question is for /u/Aethereus: How was chronic pain viewed and treated in your time period? With medicine and life being what it was then, I imagine that conditions like clubbed foot, arthritis, gout, and infections could bring with them a great deal of pain over a long period, even permanently. What sort of treatments were available to those that could afford it? Were there common \"folk remedies\" used by those without means? Were certain causes of chronic pain looked down on more than others? (for instance, I know that gout was considered a rich man's disease)",
"I recently learned that the Scientific Method is relatively new concept (i.e. developed after Newton's time). Any insight into why it took so long to formulate?",
"Hi, would someone please explain how the myth of Phlogiston stuck around for so long? This has always been really interesting to me. \n\nFollow up question, I've always been interested in fraudsters in Science who somehow managed to dupe everyone to the point where the uncovering of the fraud led science to be significantly behind. In your fields, do you have an example of such a person/A famous uncovering event ? ",
"What are the standard texts on the history of bacteriology? When I look, I find a LOT of stuff about Pasteur and Koch, but it's difficult to see where the quality is. I'm looking for something that can outline bacteriology's emergence as a field, and I'm not especially pushed if it's a more theoretically \"traditional\" work, just so I can get a sense of how it developed.\n\nAlso, are there canonical secondary texts on the \"Chemical Revolution\" in the late 18th century? I'm less interested in how bad-ass Lavoisier was than in understanding how chemistry gave scientists a new language with which to describe the universe.",
"AWWW YISSS. \n\nI notice there are a few panelists who focus on alchemy! A couple questions:\n\n* Did the esoteric/hermetic stuff associated with alchemy have anything to do with traditional European grimoires (books of magic)? How did alchemists reconcile the occult side of their practice with their religious traditions?\n\n* People who are now popularly thought of purely as scientists and vanguards of rationalism—e. g. Boyle and Newton—also did alchemy. When and how did alchemy and science come to be considered mutually incompatible by a) practitioners and b) educated people in general?",
"When I hear/read about famous historical scientists, nearly all of them are European or of European descent. Who are some of the most influential or greatest scientists from the rest of the world?",
"Can anyone comment on the impact of philosopher Karl Popper in the middle of the 20th century on science? In particular, how influential were his theories on the course of science? Did he break new ground in scientific philosophy, or did he merely codify practices that were already widespread in the field?",
"Please tell me if this statement is true: *\"The mechanical atom (say, as promoted by Boltzmann) and the chemical atom (as promoted by Dalton) were distinct hypotheses/theories until Einstein and Perrin's work in 1905, which unified these ideas.\"*\n\nI'm interested in how much interrelationship there was between the two theories. Dalton's work (and those after him) certainly seems to provide strong evidence that atoms are *real*, rather than merely useful fictions. However, many (most?) scientists continued to think of them only instrumentally (e.g., Poincare) until 1905. Is this because those scientists were thinking primarily of statistical mechanics rather than chemistry?\n\nAny information about the evidence and development of these atomic theory (theories) would be excellent.\n\nThank you all for doing this AMA!",
"Another question about the history of atomism.\n\nI am interested in a capsule summary of the corpuscular theory presented in Pseudo-Gerber's *Summa perfectionis magisterii*. What elements are Aristotelian, and what elements are distinctly corpuscularian, as, say, Boyle would recognize.\n\nI'm currently reading William R. Newman's *Atoms and Alchemy*, which is excellent, but he doesn't systematically lay out the various theories in as much detail as I would like.\n\nThanks again!",
"Everyone generally seems to be in awe of Newton as a genius of his time. However, [The Scientists by John Gribbin](_URL_0_) presents a much less rosy view. Basically, that Leibniz and others were already discovering, or would soon discover, the same concepts which Newton is famous for. And also, that Newton was a huge dick who sabotaged and black listed contemporaries that he didn't like.\n\nSubsequently when I've tried to argue Gribbin's view of Newton, people always come out in Newton's defense. So, who's right?",
"Ooh, I have a bunch of math history questions.\n\n* I was at a conference four years ago and saw [this awesome talk \\(PDF warning\\)](_URL_0_) about mathematics and imperialism. The speaker talked both how mathematics influenced imperialism and how imperialism influenced mathematics. It was a very nice change from most math history talks which tend to be basically trivia.\n\nThe talk was only 20 minutes long and so couldn't go into great detail, but I was wondering if any of you had any resources for more reading like this. It was incredibly fascinating.\n\n* On a similar note, does anyone have an opinion on *Mathematics and Western Culture* by Morris Kline? I've started reading it a couple times, but the author always came across a little to gung-ho about the importance of math.\n\n* I've read a lot about zero and its origins, but what about infinity? When did infinity start getting used in mathematics and how did its use evolve?",
"These might delve a bit inside the realm of the 20-year rule, but here we go...\n\nI recently finished a renewal course for Institutional Review Board/Biomedical Research training. Unfortunately, the history sections explaining the origin of the IRB process/national/international laws controlling research on human subjects were rather boring (brief mentions of Nuremberg Trials, Tuskegee Syphilis Study, and abuses in mental institutions). \n\nIf you care to dive a little deeper, what were the major events/factors influencing the creation of laws that determine how we conduct research on human subjects?\n\nSince their creation, have the laws controlling research on human subjects successfully balanced the need for research while maintaining dedication to respect for persons, beneficence, and justice? Have there been abuses/oversights? Has there been a call to modify modern laws to allow for more/less strict oversight of human research?",
"To all: Is there any theory that turned out to be wrong that you are particularly fond of?",
"Regarding 'gravity'. When did that word (or its etymological ancestors) come to be associated with objects falling toward the Earth? Presumably before Newton, but does Aristotle use something like this term to pick out this concept? Does Buridan? Oresme?\n\nThanks again!",
"I was authoritatively told by someone awhile back that there wasn't any real contribution to modern science that can be traced to anywhere outside of ancient Europe. So ancient China, India, and the Middle East contributed nothing to modern science. How accurate is this view? What were contributions from outside of Europe before modern times, if there were any?",
"Is technology exponential or sigmoid?",
"This may be better suited to /r/askphilosophy or /r/askscience, but anyway, is there really anything \"scientific\" about \"scientific socialism\", i.e. Marxism? ",
"My question is about the history of calculus. I don't actually understand calculus yet, it is something that I have decided I will learn this year.\n\nWhat I would like it know, if we have any details about this, is what were Newton and Leibniz thinking as they developed calculus. I know that they came up with different methods. Newton used what he called fluxions (now called infinitesimals, another concept I don't really understand), and I'm even less familiar with Leibniz's work.\n\nTo help me understand it'll probably be useful if you can explain what calculus is for, and then if possible how Newton and/or Leibniz broke down the problems (what problems? Was it planetary orbits?) that they wanted to answer making them simple enough to be able to translate into mathematics.\n\nI think it would be fascinating to know at a greater level of detail than is normally covered in texts on the history and philosophy of science, how the great achievements in logic, mathematics and science were finally achieved.",
"The most famous scientists today are usually famous because they write popular science or appear in popular media, not necessarily because they've made huge breakthroughs in their particular field. Before the last few decades, it seems like the most famous scientists were also the most important scientists. Is my perception incorrect? Is it because many famous scientists from years past did not become famous until after their death? Is it because scientific breakthroughs are more the work of teams than of individuals nowadays? Any other reason?"
]
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[] |
[] |
[
[],
[],
[],
[],
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"http://www.reddit.com/r/AskHistorians/comments/1w549x/what_is_the_importance_of_ciceros_dream_of_scipio/",
"http://en.wikipedia.org/wiki/Somnium_Scipionis"
],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
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"http://www.amazon.com/The-Scientists-History-Greatest-Inventors/dp/0812967887/ref=sr_1_3?ie=UTF8&qid=1390763876&sr=8-3&keywords=the+scientists+lives"
],
[
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],
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[],
[],
[],
[],
[],
[],
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|
51g85l
|
How strong is a single carbon nanotube?
|
Let's say someone firmly anchors a single, continuous carbon nanotube across a hallway at neck height. I walk down the hallway. What happens when I reach the tube?
Do I harmlessly break the tube?
Do I get a cut to my neck?
Do I get decapitated?
Edit to say: I couldn't decide if this was a "physics" question or an "engineering" question.
|
askscience
|
https://www.reddit.com/r/askscience/comments/51g85l/how_strong_is_a_single_carbon_nanotube/
|
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"I can't find an actual value for the strength (on my phone) but the CNT will break. CNTs have high strengths and very small diameters so the failure stress (load/area) will be very high, but as the area is very, very low, the actual load (how much energy it takes to break it) will be very low.\n\nIt's also worth noting that CNTs are very, very short. 1 mm length is very very, very long for a CNT.",
"From what I can find, a carbon nanotube has a diameter of about 50 nm. The highest theoretical strength is 126.2 GPa, but actual testing gives the much weaker strength of 13-53 GPa, presumably to imperfections and not having the best structure. Let's go with 53 GPa. Using that, and assuming a square packing, each nanotube would have a strength of about 316 micronewtons. Also, this method gives a huge mechanical advantage to you. Theoretically carbon nanotubes can stretch to 23.1% beyond their original length, but testing gives 16%. Let's go with 16%. The portion of the strength you feel would be sqrt(1-1.16^(2)) = 59% of what the nanotube feels, so you'd only get about 185 micronewtons.\n\nThe area is small too. It's 50 nm by, let's say a decimeter. Pressure works out to about 37 kN. But I don't think that's the right way to look at it. Suppose it has 185 micronewtons times, say 0.1 meters. That works out 18.5 microjoules. There's a minimum energy to cut things in half, and I don't think this will cut it. I'm betting you harmlessly break the tube."
]
}
|
[] |
[] |
[
[],
[]
] |
|
65rqf5
|
What Che Guevara really thought about homosexuality, race, diversity and democracy?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/65rqf5/what_che_guevara_really_thought_about/
|
{
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"text": [
"[I'd recommend this AskHistorians thread](_URL_0_) which answers many parts of your questions."
]
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|
[] |
[] |
[
[
"https://www.reddit.com/r/AskHistorians/comments/1lt4rb/was_it_the_truth_behind_the_critical_controversy/"
]
] |
||
21x7hb
|
i flip a coin 3 times. the first two times i get heads, why is there a 50/50 chance i'll flip heads again but a 12.5% chance i'll flip 3 heads in a row?
|
Mathematically, this makes sense and I do fine with probability calculations and all that but this has always vexed me. If the probability of flipping heads 3 times in a row is 12.5% and I've already flipped heads 2 times in a row, doesn't it stand to reason that my probability of flipping heads a 3rd consecutive time is lower than 50%? My reasoning being that it is more unlikely to get that result 3 consecutive times rather than just once. I understand that you are to view that 3rd flip as an independent event but it just always bothered me.
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/21x7hb/eli5_i_flip_a_coin_3_times_the_first_two_times_i/
|
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"text": [
"You have **already** made an improbable event happen by flipping heads **2** times. The last one is relatively easy. Like standing on the shoulders of giants.",
"There is a 12.5% probability of flipping three heads in a row, as you say.\n\nThere is also a 12.5% probability of flipping three coins and getting heads/heads/tails in that order.\n\nAt this point, you've already flipped two heads. There are only two possible outcomes now, and they both have the same probability. They were both 12.5% probable before you started, but now you've already flipped the first two coins and got two heads, they are both 50% probable.",
"The reason that the previous coin tosses do not influence the third coin is because outcomes of a coin toss are independent. Each and every coin toss for any fair coin will have a 50/50 chance of showing heads. This is because the other coins have no way of influencing the third toss. The reason the probability of flipping 3 heads in a row is due to conditional probability. The probability of flipping heads on the first coin is 0.5. The probability of flipping the second heads by itself is 0.5. However, in order to have 2 heads in a row, the probability would be 0.5 given that the first coin was heads. The probability of flipping the third heads is 0.5 by itself. However, again, in order to have 3 heads in a row, the probability would be 0.5 given that the first 2 coins were heads. This can be shown by the probability model P(3rd coin is heads|the first 2 coins were heads) which equals 1/8. Another way to see this is to write down all the possible combinations of flipping 3 coins. You will see that there are 8 options; only one of which is 3 heads. 1/8 = 0.125\n\nEdit: Source - I'm a statistician.",
"Chance has no memory"
]
}
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[] |
[] |
[
[],
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|
1h5mm5
|
Why did some animals evolve to lay eggs? Wouldn't it be more energy-efficient to have eggs inside your body instead of laying them and then having to care for them (like chicken do for example)?
|
I am sorry if I sound ignorant or stupid, I am a historian.
|
askscience
|
http://www.reddit.com/r/askscience/comments/1h5mm5/why_did_some_animals_evolve_to_lay_eggs_wouldnt/
|
{
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"text": [
"First a small evolutionary history quibble: egg-laying evolved before internal fertilization and egg-bearing (leading to live birth) did! Think of how salmon breed: the female lays a bunch of unfertilized eggs, then the male comes and fertilizes them. This is the \"ancestral condition\" from which internal fertilization and then viviparous (internal egg-bearing to birth live young) evolved.\n\nLife started in water. The first sexually reproducing animals were all aquatic. In this environment, there was no need to directly exchange gametes (via sex/internal fertilization), so a simpler system of laying unfertilized eggs and then fertilizing them developed. Typically, a massive quantity of eggs would be laid, fertilized and then abandoned. This requires minimal parental investment, and ensured that some offspring would hatch and survive through sheer numbers.\n\nLater, we saw the development of internal fertilization. A good example that's still around are some species of shark, like the [dogfish](_URL_1_). They have a rudimentary form of internal fertilization with a modified structure called a clasper, which provides a channel for sperm. Now dogfish actually bear live young (viviparous). However because of how energy intensive it is to carry offspring, they have only a few at a time, but because they are not as vulnerable while developing internally, their survival rates are higher. To see the rationale for egg laying we can look to another animal.\n\nThe turtle! Turtles have internal fertilization (via their [hemipenes](_URL_2_) < -- **warning gross**). This strategy makes sense because turtles came to land. On land, you *have* to reproduce internally because the air would dry out the eggs. Once the eggs are fertilized, they are coated in a protective shell so they don't dry out, and laid in a nest. This nest is then abandoned (again, minimal parental investment and large numbers of young).\n\nSo as you can see, for many animals laying eggs is a sound strategy for reproduction and survival! Birds are interesting because they lay very few eggs (generally similar to the number of offspring produced by viviparous animals), and invest considerable energy in rearing them until they are independent. Of interest to you would be [r/K selection theory](_URL_0_) which explains in detail the different lifestyle strategies of high numbers of offspring and low parental investment vs low numbers of offspring and higher parental investment."
]
}
|
[] |
[] |
[
[
"http://en.wikipedia.org/wiki/R/K_selection_theory",
"https://en.wikipedia.org/wiki/Spiny_dogfish",
"http://en.wikipedia.org/wiki/Hemipenis"
]
] |
|
3ud55f
|
what is the 2nd world
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/3ud55f/eli5_what_is_the_2nd_world/
|
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"text": [
"During the Cold War, the Second World referred to either the Soviet Union and its allies, or all Communist countries. Depends on who you ask.",
"* 1st World: US, NATO, and allies\n* 2nd World: USSR, Warsaw Pact, and allies\n* 3rd World: Unaffiliated states\n\nAs the USSR and Warsaw Pact no longer exist there are no more 2nd World nations.\n\nThe Reason \"3rd world\" came to refer to poor countries is because basically everyone with any economic or military clout to speak of had chosen a side during the Cold War. The unaffiliated states were mostly poor countries that had little global influence and so hadn't been absorbed by one of the big alliances."
]
}
|
[] |
[] |
[
[],
[]
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||
376f5h
|
Reddit, what's the best way to get a full read on Russian history?
|
Are there any good resources/books to read?
Any advice on getting an unbiased [within reason] chronological timeline?
Any advice in general?
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/376f5h/reddit_whats_the_best_way_to_get_a_full_read_on/
|
{
"a_id": [
"crkb4nc"
],
"score": [
2
],
"text": [
"Unfortunately, there is no one book or resource that can encapsulate the incredibly diverse and variegated history of Russia. To get something approaching a full read, one should read multiple books and articles. One of the better ways online to find out which books to read is to examine the reading lists produced for PhD qualifying exams. Some history departments save themselves the trouble of having the candidates come up with their own lists and publish their own masterlist of reading materials.\n\nOne of the more useful guides for navigating the masses of books on Russian/Soviet history is [UIUC's reading list for PhD exams](_URL_0_). Although it does not incorporate scholarship after 2007, the list is very thorough and organized with key texts highlighted by an asterisk. "
]
}
|
[] |
[] |
[
[
"http://www.history.illinois.edu/graduate/prospective/fields/russia/reading/"
]
] |
|
1s74qi
|
Were there any major naval battles during the 30 years war?
|
Were there any major naval battles during the 30 years war? Maybe involving France and Spain?
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/1s74qi/were_there_any_major_naval_battles_during_the_30/
|
{
"a_id": [
"cdupdvv"
],
"score": [
5
],
"text": [
"The answer to this, like most 30 years war questions, is yes, maybe, sort of, and after a fashion but it wasn't really what you think. There were a lot of Naval engagements between Spain and the Dutch during the period of the Thirty Years War, and both of them were major players in that conflict (except when only one of them was and the other wasn't, or neither of them was, or when they were technically not involved but heavily involved anyways, or when they were technically involved but not really doing anything). If you think I'm laying it on a little thick you should read up on the thirty years war, which will be difficult, because there isn't a lot of great literature on the subject (I know, this is one of my current pet projects).\n\n Anyways, Spain and the United Provinces (the Dutch) had been fighting an 80 years war already and the Thirty Years War happened during that. It's hard to place their naval engagements as part and parcel with the Thirty Years War conflicts, even though they were a part of them. There were other major naval engagements though. The two biggest involving Spain and France were the Relief of Genoa and the Battle of Orbetello. Orbetello was fought by galleys towing sailing ships due to lack of wind, and there were few losses on either side, though the Spanish outmaneuvered the French and gained the advantage because of this. \n\n The relief of Genoa was a much bigger affair. Genoa was a traditional ally of Spain, and a critically placed one, because it dominated both the sea lanes and road between Hapsburg Spain and Hapsburg Austria/Central Europe. Since France blocked most land communication between Spain and Central Europe keeping the road they had open from Genoa was a hugely important strategic aim of Spain, and closing it hugely important for Spains enemies. Starting problems and forcing Spain to respond militarily to them was also a clever way for Spains enemies to bleed the wealthy Spanish court of their American currency. It was to this aim that France supported the Duchy of Savoy in besieging Genoa, the Spanish were able to relieve the siege using a fleet of galleys. This successful action was at a high point for Spain, shortly after they were able to make a truce with France, and beat off an English fleet attacking Cadiz.\n\n If you really want to bone up on the thirty Years War you might try The Thirty Year's War: Europe's Tragedy by Peter H. Wilson. It is quite long, quite heavy, and very informative. I'm reading it right now, I wouldn't approach it lightly (if you prefer pop history you need a different war) but I'm enjoying it quite a bit, albeit slowly."
]
}
|
[] |
[] |
[
[]
] |
|
p5oxo
|
What is that 'curtain' of gaseous stuff that we usually see falling down the sides of a rocket during launch ?
|
If you look closely at rocket launches (Saturn V or maybe other rockets too) you will find some kind of a curtain of gaseous stuff falling over its sides. Till this day, I have no idea what that is :(
Photo: _URL_1_ and _URL_0_
I have this nagging question ever since I was a kid (now I am 30 but no answer in sight). I am hoping someone here can answer my question.
Thanks!
|
askscience
|
http://www.reddit.com/r/askscience/comments/p5oxo/what_is_that_curtain_of_gaseous_stuff_that_we/
|
{
"a_id": [
"c3mpu6l"
],
"score": [
4
],
"text": [
"ice- most modern rockets are hydrogen based. And are propelled by large amounts of liquid oxygen in hydrogen, making the surfaces of the rocket very cold before launch, enough that ice forms on the surface, which then falls off during launch. "
]
}
|
[] |
[
"http://imgur.com/KfQEv",
"http://imgur.com/yzEDk"
] |
[
[]
] |
|
5x3d2r
|
Is the European Union the first attempt to unify a whole continent peacefully ?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/5x3d2r/is_the_european_union_the_first_attempt_to_unify/
|
{
"a_id": [
"def9wsd",
"deh00gl"
],
"score": [
50,
3
],
"text": [
"The broad answer is \"probably yes\" but it depends on how you define the question.\n\n1. Is the EU a unification project? I think it is - and it's quite clear from the text of the Maastricht Treaty and the statements of politicians at the time of its signing - but it's definitely a disputed point (hard to cover the dispute in any detail without breaking the rule against present-day events though). It also depends on what you define as unification - whether that would a single federation, or if the existing situation of a common market and currency already qualifies.\n\n2. How far are you willing to stretch \"peacefully?\" The other examples of continent unification I can think of are the colonisation of Australia and the Spanish control of South America (which, if we include the personal union with Portugal, covered the whole continent). The former did see many conflicts with Aboriginal tribes, but these were mostly local in nature and involving settlers rather than the British army or police forces, and so you could perhaps call it \"peaceful\" at a stretch. The latter of course involved many bloody wars against the South American kingdoms and is not at all peaceful.\n\n3. The EU does not technically span the whole continent. Aside from those which the EU wants to join at some point but have so far refused (i.e. Switzerland and Norway), those which are leaving (current events alert) and those, like Serbia, which are not yet members but would like to be at some point, there is an elephant in the room: Russia. The European part of Russia comprises about four-tenths of Europe's total land area, yet Russian membership of the EU has rarely even been contemplated. This is chiefly a legacy of the Cold War and the EU's roots as a *Western European* political project - and therefore Russia is conceived of as a distant rival rather than another European country.\n\nMy personal view is that for the purpose of historical comparisons, the EU is best considered as a large, loosely organised empire, in some ways comparable to the Holy Roman Empire or perhaps Austria-Hungary. But really, these comparisons are fairly useless as the EU is historically unique - such a large union of so many different countries has never been attempted before.",
"I'd like to suggest Kwame Nkrumah's attempts to unify African states, in 1958 and formally in 1963, with a pan-African movement as being the first attempt to unify a whole continent peacefully. With the speech \"Africa Must Unite\", Nkrumah fought to bring newly independent nations together through the aims of \"one man one vote\", which would bring all African nations to share and debate how best to progress their shared resources and interests, newly free from colonial rule.\n\nIn 1958, Nkrumah, the newly elected Ghanain leader, hosted the leaders of Egypt, Ethiopia, Liberia, Libya, Morocco, Sudan and Tunisia to discuss how best to achieve progression for the rest of the continent and fight the exploitation of their peoples by colonial rulers. The result of which was the leaders signing the Charter for the Union of African States whose stated aims were to:\n\n- create better lines of communication and co-ordination between leaders, reducing incidents\n- defend the sovereignty and independence of all states\n- eradicate all forms of colonialism\n- ensure the provision of Human Rights for all citizens\n- raise living standards for all people\n\nwith provision for potential new members. \n\nAs new members joined, two blocs formed with competing ideologies of how best to progress their shared aims. The mainly sub-Saharan bloc who believed in a mainly economic linked continent, not unlike the recently ratified Treaty of Rome which created the European Economic Community. While the mainly North African states believed a federation of states would be better equipped to ensure progression.\n\nIn spite of the cold war, foreign interference, assassinations and reliance on colonial institutions, the Organisation of African Unity were able to cement independence for all of its member states to varying degrees, the end of apartheid, the development of the African Development Bank and finding a voice within the UN. However, due to the previously mentioned interference, the organisation was not without its criticisms; mainly due to the lack of a standing army and impotence when confronting civil wars, dictators and human rights abuses from leaders.\n\nIn 2002, the Organisation of African Unity was disbanded and reformed as the African Union to better streamline the OAU and African Economic Communities treaties into a single organisation.\n\nKwame Nkrumah - Africa Must Unite _URL_0_"
]
}
|
[] |
[] |
[
[],
[
"http://feintandmargin.com/wp-content/uploads/2015/04/Africa-Must-Unite.pdf"
]
] |
||
82hw5j
|
When did the sentiment, "That America was founded on Christian principles", begin to be popularized?
|
I was reading about the [Treaty Of Tripoli](_URL_0_), specifically article 11. For those unfamiliar, this treaty was signed in 1796 by President John Adams, one of the founding fathers.
Article 11 of the treaty states that:
"As the Government of the United States of America is not, in any sense, founded on the Christian religion; as it has in itself no character of enmity against the laws, religion, or tranquility, of Mussulmen (Muslims); and as the said States never entered into any war or act of hostility against any Mahometan (Mohammedan) nation, it is declared by the parties that no pretext arising from religious opinions shall ever produce an interruption of the harmony existing between the two countries."
This treaty was ratified unanimously in the senate, without debate. John Adams himself even said:
"I have ordered the premises to be made public; And I do hereby enjoin and require all persons bearing office civil or military within the United States, and all other citizens or inhabitants thereof, faithfully to observe and fulfill the said Treaty and **every clause and article thereof.**"
So to me, it seems pretty clear that this unequivocally proclaims the United States as a secular nation not founded on christian values. So if that is the case, then when did the idea that America **was** founded on christian values begin to circulate?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/82hw5j/when_did_the_sentiment_that_america_was_founded/
|
{
"a_id": [
"dvanj1z"
],
"score": [
110
],
"text": [
"This is a great question! I will love to jump into it.\n\nThis notion that America was founded on as a Christian nation stems religious revivals that took America by storm during the first half of the 19th century. This period, often regarded as the \"[Second Great Awakening](_URL_1_)\" began in a period right after the Constitution was created (usually around 1790) and lasted until 1840. This movement flourished in American history, causing many new sects of Christianity to be created (like Mormonism) along with seeing established minorities (like Millennialists) transform into what would become the Evangelical movements. In order to explain what changed, I feel like it's worthwhile to address what things were like *before* 1790, otherwise, it appears to be much less significant as to why things changed.\n\n**Pre-Constitution American Religious History** \nAmerica's early religious history is quite different from what most people believe today. If you were doing a straw poll in 1775 and asked colonists from all over the 13 colonies, “Do you identify as a Christian?” the overwhelming majority would say, “yes,” however, it leads to another question that begs to be answered: What did “being a Christian” mean in 1775? Most Christians didn’t simply identify themselves as “Christian” when regarding their religion. More importantly, they did not view *others* as Christian simply because they were a part of a Christian denomination. By 1775, well over a dozen major sects of Christianity were present across the United States, and some were more divisive than others. The most popular religion was the Anglican Church, whom, by 1775, had majority populations in many states, including Maryland, where at least 66% of their 94,000 population (of white people) was estimated to be Anglican.(1) About 7.5% were Catholic, about 6% Presbyterian, about 3% Quaker and the remainder being various other sects, (Unitarian, Methodists, etc.) This is just one example, but it's an easy example to show that most people identified as one of these major sects. However, that does not mean that because someone identified as part of a religion, that it was actively part of their life.\n\nHistorians acknowledge that while most American professed to being religious, around 15% actually belonged to a church in 1775 and at most, 20% of Americans attended at least one church service annually.(2) This varied from state to state, with people in South Carolina having the highest rate of annual church attendance (30%) versus rural parts of New York, now present day Vermont having the lowest (10%). It's worth mentioning that there was also a strong distrust of people of different faiths during this period. Protestants distrusted Catholics. Everyone distrusted Quakers (who, generally speaking, refused to fight or support the war). And nearly all minority religions hated Anglicans because Anglicans had all the power during the pre-war years. \n\nThe idea of saying that America was established as \"Christian Nation\" is factually inaccurate because to 18th century Americans, being a Christian was not good enough. You had to be the *right type* of Christian, thus people relied on a form of tribalism that splintered parts of the country. During the American Revolution, multiple states, including Pennsylvania and Maryland both had state legislatures that sought to prevent people of some religions from voting and/or holding public office.(3) The wording also precluded non-Christians, specially Jews from having any say in the democratic process.(4) Things changed in every state during the next decade, but there was a ton of fighting for it. A minority voice in the Virginia state legislature fought to impose a tax to support local churches during the 1780s, and was even privately supported by Founders like George Washington, but was shot down in 1786.(5) My major point is that there was a lot of distrust and between people of different religions which in turn caused a ton of friction between feuding sects during this period.\n\nThe victory of the American Revolution deeply emboldened many founders where most, generally speaking, did not hold passionate religious convictions. (6) Jefferson’s Thomas Jefferson and the Virginia Statute for Religious Freedom stands as an obvious example of this, but I actually went into a lot [more detail about this in another post](_URL_0_). Private letters from the founders to each other also suggest that it was extremely important to them that America be established as a place deeply rooted in secular ideals.\n\n**Post Constitution American Religious History** \n\nSo how did the narrative change? Well, as stated above, the tone of Religion began to change in 1790, but really started to ramp up in the 1810s. Jon Butler, a leading American religious historian repeatedly argued that the reason we believe today that the earliest generations of Americans were highly religious, and in turn started to claim we were a \"Christian Nation\" is because later generations desired that we believe it. Butler argues that religion was used as a tool for the religiosity of later generations who were exaggerating and even fabricating some of their claims about America’s religious past to spread their own messages. This can clearly be seen in many of his works, including his book *Awash in the Sea of Faith: Christianizing the American People*. In this book, Butler also explains that America’s religious leaders feared this secularization, and sought to bring back religion into American society. Here Butler explains: \n\n > Between the signing of the Declaration of Independence in 1776 and George Washington’s death in 1799, American church and denominational leaders renewed efforts to stamp Christian values and goals on a now independent society. three of these attempts proved especially important: powerful Christian explanations of the Revolution and of the proper political order that ought to govern American society, attacks on irreligion, especially on skepticism and deism, and the creation of new religious groups, which evinced principles that for the first time might be called distinctively American. (pp 212)\n\nThis push towards having a religious revival was not orchestrated by united leaders of different Christian denominations, but rather happened independently that road the waves of change in American society during this period and can be seen when examining independent religions. Methodists, which were a minority religion in 1776, boomed to having 250,000 members by 1820, and by 1830, that number doubled. (7) Similar themes for Bapists happened, where their numbers tripled between 1783 and 1813.(8) Part of why this was so effective is that Christianity became an effective enterprise where being a part of a growing church was highly desirable.(9) Part of this revival also intertwined from the desire to repaint America’s origin stories as being extremely virtuous and Christian. An example of this can be seen through biographies written on the founders by American pastors and ministers. Mason Weems, for example, invented the story of George Washington being unable to tell a lie about chopping down his father’s cherry tree. [The story appears in his fifth edition of Washington’s biography, and is certainly a figment of his imagination](_URL_2_) however it was at the beginning of a trend that sought to paint the founders as deeply moral men that would never do anything that lacked virtue. This is especially true for other founders who held deistic beliefs, which was harshly frowned upon by the 1810s.(10)\n\nUltimately, the founders sought to instill secular values into the American government when support of organized religion was comparatively low. When religious revivalism spread through America during the ensuing decades, people sought to portray America’s religious history as being deeply rooted in Christianity, although the sources do not suggest this is true. \n\n\n1) Maryland State Archives, *Brown Book:* Letter from A.(?) L.S. 1781 April 17 - 461 VII. 71 pp 89\n \n2). Jon Butler. \"Magic, Astrology, and the Early American Religious Heritage, 1600-1760\" *The American Historical Review*, Vol. 84, No. 2. Apr., 1979, pp. \n\n3) Alan Taylor. *American Revolutions: A Continental History*, 1750-1804. W. W. Norton & Company; 1 edition. 2016. pp 359\n\n4) R. Marie Griffith. *American Religion: A Documentary History* Oxford University Press. New York. 2008 pp 148-149\n\n5) Proposed Resolution of the Maryland House of Delegates. Broadside, January 12, 1785. Broadside Collection, Rare Book and Special Collections Division, Library of Congress pp 131\n\n6) John Butler: *Awash in a Sea of Faith: Christionizing the American People* Oxford University press, 1992. pp 214\n\n7) Nathan Hatch. *The Democratization of American Christianity*. Oxford University Press. 1990. pp 3\n\n8) Hatch. pp 3\n\n9) Hatch pp 4\n\n10) Butler. pp 214\n"
]
}
|
[] |
[
"https://en.wikipedia.org/wiki/Treaty_of_Tripoli"
] |
[
[
"https://www.reddit.com/r/AskHistorians/comments/7tkwsa/during_the_early_days_of_american_independence/dtfij23/",
"http://www.ushistory.org/us/22c.asp",
"http://www.mountvernon.org/digital-encyclopedia/article/cherry-tree-myth/"
]
] |
|
om2v9
|
Are stars visible in daylight?
|
Today at 5:20pm pst I stepped out onto my back porch to toss my dog his ball. I looked to my left up into the evening sky. It was not even dusk yet, the sky was still light blue and there was cloud cover as we are expecting a big winter storm overnight. I saw a decent sized glowing light in the sky and it appeared to be on the bottom side of the cloud cover. It did not move or flash like an airplane or a helicopter. I asked my husband and son to come look and after discussing it for about 3 minutes I got my camera and videoed it for 16 mins. It randomly faded at times, but it never moved. I had my husband look up the sky on Google sky map and it showed Rigel in that area but would it be possible to see a star that vividly in the daytime sky? It was really very light out at the time. I have checked around on the internet and cant really find an answer to my question. I am about 30 miles south of Seattle and the light was in the southwest sky.
Thanks for any info that is given.
|
askscience
|
http://www.reddit.com/r/askscience/comments/om2v9/are_stars_visible_in_daylight/
|
{
"a_id": [
"c3iczlg"
],
"score": [
5
],
"text": [
"It was Venus. Venus is bright enough to be seen in day light. Other planets and stars are too dim. Actually they are as bright during the day as they are during the night, but the sky is brighter so you can't see them. The brightness of the sky depends on atmosphere conditions. If you go high into the mountains, the sky will be darker and more planets and even stars are visible during the day. If you go up to 50 kilometers or so, the sky will become dark like in space. In space you see stars and Sun at the same time and there is no bright glow around the Sun as on Earth.\n\nThank you for being rational and came here to ask instead of filling the news and you tube with \"UFO videos\"."
]
}
|
[] |
[] |
[
[]
] |
|
1scmzz
|
what happens to particles when they dissolve?
|
Do they just get so microscopically small that we can't see them or do their molecules split or something or other?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1scmzz/eli5_what_happens_to_particles_when_they_dissolve/
|
{
"a_id": [
"cdw67wt",
"cdw6few"
],
"score": [
2,
4
],
"text": [
"Substances that dissolve, do so because they are polar and are introduced into a non-polar solution. What happens is that the bonds between the polar molecule will be affected by the non-polar solution and eventually the molecules will break their bond and dissolve in the solution. Do they get microscopically small? Yes, they basically are single atoms, or simple compounds which are as small as manometers or so. Do the molecules split? Depends on what you mean, if you are talking about atom splitting then no.\n\nThis is not at all fact checked in any single way. I went for a very simple explanation.",
"If the solute is an ionic compound such as salt, then the crystalline lattice is broken up by the polar solvent (such as water) and each ion is held in the liquid by inter molecular hydrogen bonds.\n\nSo you are correct, the molecules split at the microscopic level. \n\nIf however, you are referring to, say, sugar, which is not an ionic compound, the dissolution occurs due to partial charges, in which certain atoms (carbon and oxygen in this case) pull the electrons from the hydrogen, leaving a naked positive charge. This also allows the sugar to dissolve in water in the same way as charged ions."
]
}
|
[] |
[] |
[
[],
[]
] |
|
jhyd9
|
how is blood pressure measured? why do
doctors measure it? what does it tell them?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/jhyd9/eli5_how_is_blood_pressure_measured_why_do/
|
{
"a_id": [
"c2c9tf3",
"c2cbf6s",
"c2c9tf3",
"c2cbf6s"
],
"score": [
20,
8,
20,
8
],
"text": [
"Blood pressure can be measured in many ways. Most commonly we use sphygmomanometers (you may know them as \"blood pressure cuffs\"). They wrap around your bicep to measure your radial pulse. On top of using the sphygmomanometer, we use a method called ausculatory method, which basically means inflating the sphygmomanometer cuff an using a stethoscope and listening to the pulse at your elbow. Note that when in a clinical setting, such as when you're admitted into a hospital, we'll hook you up to a machine so that we can log your pressure.\n\nUs nurses are usually the ones who get these readings, not MD's. I'll sum up your last two questions into one. We care about blood pressure because it is a part of the vital signs. Other vital signs include temperature, pulse, and respiratory rate. What blood pressure readings tell us is how much pressure is being put onto your arteries for each heart beat. Your BP varies from a low point (diastolic) and a high point (systolic) during each heart beat. The systolic number tells us how much pressure is being exerted in the arteries as the heart squeezes out blood during each beat. The diastolic number tells us the amount of pressure in the heart when it is heart relaxes before the next beat.\n\nWhen you hear them say it's, for example, \"120 over 80\", they are specifying how much pressure in terms of millimeters of mercury (mm Hg). \n\nWe care about this because, as an adult your BP should be below 120/80, between ~90/~60 and ~119/~79. This is what we consider in the normal, healthy range. \n\nAnything below ~90/~60 is what we call **hypo**tension. Typically people who are **hypo**tensive are so because of shock, or manually by vasodilation (note: vasodilation is when we want to open the blood vessels to increase flow of blood). \n\nWhen your BP is between ~120/~80 and ~139/~89, you're considered pre-**hyper**tensive. Generally people who are overweight are in this range most of the time. This is your body telling you something is wrong and you need to fix it. You cannot live in this range for long, and it only gets worse.\n\nFrom pre-**hyper**tensive we get to **hyper**tensive, or high blood pressure. This range is anything from ~140/90 and ~179/109. Your body starts to fail. You are at risk for heart attacks and strokes (due to the thickening of arteries which is called atherosclerosis). You're at risk for an aneurysm, which if ruptures, is usually fatal. Kidneys start to fail because of the narrowed blood vessels. Your vision can deteriorate due to narrowed blood vessels.\n\nAnything above ~180/~120, you gonna' die! Get help immediately. Risks are fluid on the lungs (pulmonary edema), brain swelling and/or bleeding, a tear in your arteries, heart attack, stroke, and if you're pregnant, seizures (aka eclampsia).\n\nHope this helped\n\nedit: fixed mixup of systolic/diastolic",
"Like you're 5.\n\nYour heart pumps blood around your body through tubes called \"Blood Vessels\". These tubes can stretch and squeeze to get more blood to certain places (like when you fall down and get hurt) and keep blood away from places (like when your hands are cold).\n\nDoctors can tell a lot about a person by measuring how strong their heart is pumping blood, and how much their blood vessels are stretching. They do this by measuring your \"Blood Pressure\"\n\nThey use a special tool that you can see on the wall of the Doctor's office. It wraps around your arm and holds on with velcro. Then the Nurse or Doctor makes it squeeze your arm. This is also squeezing the blood vessels in your arm and (just for a little bit) stopping the blood from flowing through them. The amount of squeezing is measured on a dial, a digital display, or on a thing that looks like a big thermometer.\n\nThe nurse, or Doctor slowly releases the squeezing and and when just enough squeezing is released, suddenly the blood will start flowing through your blood vessels in your arm. This shows how strong your heart is working. Then they keep releasing the squeezing and they can tell how much your blood vessels were stretching. These two numbers can help tell a Doctor if you're losing blood somewhere, or if your blood vessels are squeezing too much (some old people's blood vessels squeeze too much and they need to take medicine to make them better) or squeezing too little, which sometimes happens when you get sick.\n\nBecause this measures how strong your heart is right now, and the Doctor doesn't have to wait for complicated tests or procedures, Blood Pressure is a very important way that Doctor's check to see if someone is healthy. ",
"Blood pressure can be measured in many ways. Most commonly we use sphygmomanometers (you may know them as \"blood pressure cuffs\"). They wrap around your bicep to measure your radial pulse. On top of using the sphygmomanometer, we use a method called ausculatory method, which basically means inflating the sphygmomanometer cuff an using a stethoscope and listening to the pulse at your elbow. Note that when in a clinical setting, such as when you're admitted into a hospital, we'll hook you up to a machine so that we can log your pressure.\n\nUs nurses are usually the ones who get these readings, not MD's. I'll sum up your last two questions into one. We care about blood pressure because it is a part of the vital signs. Other vital signs include temperature, pulse, and respiratory rate. What blood pressure readings tell us is how much pressure is being put onto your arteries for each heart beat. Your BP varies from a low point (diastolic) and a high point (systolic) during each heart beat. The systolic number tells us how much pressure is being exerted in the arteries as the heart squeezes out blood during each beat. The diastolic number tells us the amount of pressure in the heart when it is heart relaxes before the next beat.\n\nWhen you hear them say it's, for example, \"120 over 80\", they are specifying how much pressure in terms of millimeters of mercury (mm Hg). \n\nWe care about this because, as an adult your BP should be below 120/80, between ~90/~60 and ~119/~79. This is what we consider in the normal, healthy range. \n\nAnything below ~90/~60 is what we call **hypo**tension. Typically people who are **hypo**tensive are so because of shock, or manually by vasodilation (note: vasodilation is when we want to open the blood vessels to increase flow of blood). \n\nWhen your BP is between ~120/~80 and ~139/~89, you're considered pre-**hyper**tensive. Generally people who are overweight are in this range most of the time. This is your body telling you something is wrong and you need to fix it. You cannot live in this range for long, and it only gets worse.\n\nFrom pre-**hyper**tensive we get to **hyper**tensive, or high blood pressure. This range is anything from ~140/90 and ~179/109. Your body starts to fail. You are at risk for heart attacks and strokes (due to the thickening of arteries which is called atherosclerosis). You're at risk for an aneurysm, which if ruptures, is usually fatal. Kidneys start to fail because of the narrowed blood vessels. Your vision can deteriorate due to narrowed blood vessels.\n\nAnything above ~180/~120, you gonna' die! Get help immediately. Risks are fluid on the lungs (pulmonary edema), brain swelling and/or bleeding, a tear in your arteries, heart attack, stroke, and if you're pregnant, seizures (aka eclampsia).\n\nHope this helped\n\nedit: fixed mixup of systolic/diastolic",
"Like you're 5.\n\nYour heart pumps blood around your body through tubes called \"Blood Vessels\". These tubes can stretch and squeeze to get more blood to certain places (like when you fall down and get hurt) and keep blood away from places (like when your hands are cold).\n\nDoctors can tell a lot about a person by measuring how strong their heart is pumping blood, and how much their blood vessels are stretching. They do this by measuring your \"Blood Pressure\"\n\nThey use a special tool that you can see on the wall of the Doctor's office. It wraps around your arm and holds on with velcro. Then the Nurse or Doctor makes it squeeze your arm. This is also squeezing the blood vessels in your arm and (just for a little bit) stopping the blood from flowing through them. The amount of squeezing is measured on a dial, a digital display, or on a thing that looks like a big thermometer.\n\nThe nurse, or Doctor slowly releases the squeezing and and when just enough squeezing is released, suddenly the blood will start flowing through your blood vessels in your arm. This shows how strong your heart is working. Then they keep releasing the squeezing and they can tell how much your blood vessels were stretching. These two numbers can help tell a Doctor if you're losing blood somewhere, or if your blood vessels are squeezing too much (some old people's blood vessels squeeze too much and they need to take medicine to make them better) or squeezing too little, which sometimes happens when you get sick.\n\nBecause this measures how strong your heart is right now, and the Doctor doesn't have to wait for complicated tests or procedures, Blood Pressure is a very important way that Doctor's check to see if someone is healthy. "
]
}
|
[] |
[] |
[
[],
[],
[],
[]
] |
||
1jkoim
|
Did homer's odysey exist by 700BC?
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/1jkoim/did_homers_odysey_exist_by_700bc/
|
{
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"text": [
"It depends what you mean by 'The Odyssey'.\n\nThere are several theories for how the poem was composed - one popular theory is ['oral composition'](_URL_0_); instead of being composed by an individual poet, advocates of this theory postulate that the story of the Odyssey would be recited by a poet with a unique composition, aided with structuring tools including 'ring cycles', epithets and such.\n\nOur source for 'The Odyssey' is an edition pieced together from the Library at Alexandria, it's not the definitive poem.\n\n[Start with this wiki article for an introduction](_URL_1_). It's traditional to call the Odyssey and Iliad's composer 'Homer', but opinion is split as to whether there actually was a geezer called Homer who came up with all this great poetry.",
"The question you are asking cannot be answered. Ever. Because what you call \"Homer's Odyssey\" does not exist, not in the way that you are thinking about it. Here's a [thread](_URL_0_) that was supposed to be about the historical relevance of the Homeric Poems to actual events at the end of the Bronze Age in Greece, but which rapidly evolved into a thread discussing the nature of the composition of the Homeric Poems."
]
}
|
[] |
[] |
[
[
"http://faculty.gvsu.edu/websterm/oralcomposition.htm",
"https://en.wikipedia.org/wiki/Homeric_Question"
],
[
"http://www.reddit.com/r/AskHistorians/comments/1i0goq/what_evidence_is_there_on_the_trojan_war/"
]
] |
||
5uflos
|
why is doing the paperwork for income called "paying taxes" when the taxes are already taken from our paychecks?
|
Are people meaning to say "filing taxes" instead?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/5uflos/eli5_why_is_doing_the_paperwork_for_income_called/
|
{
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"Your taxes are not taken away from your paycheck. The money from your paycheck to the IRS is only prepaid taxes. The amount you pay is an estimate on how much you will have to pay in taxes at the end of the year. The forms you are filling out is to find out how much you actually have to pay in taxes. Sometimes you have paid too little and sometimes you have paid too much. It is theoretically possible to not pay any tax from your paycheck and then get a giant bill from the IRS in the spring. Also if you get some giant investment return that would result in your taxes being much higher then normal you can pay the IRS while you have the money on hand instead of getting the bill at the end of the year.",
"It's not called \"paying taxes.\" It's called \"filing a tax return.\" People are just sloppy when discussing some subject because you know what they mean.",
"Different activities. If someone says, \"I object to paying taxes,\" they're probably a libertarian who believes in defunding the government. If someone says, \"I object to filing taxes,\" they're probably a person with moderately complicated finances who doesn't understand how, in these days when employers and banks already have to report everydangthing to the government, the government can't just *use* that information to calculate my tax for me?\n",
"There are many people who have to write checks to the gov't for unreported income and non-tax-withheld income. \n \nIf you make a certain amount of money, it needs to be done quarterly in the US. Otherwise it can be done yearly. ",
"It is not called paying taxes. At least not commonly by anyone in the US. It is called filing taxes, filing your tax return, or doing taxes. \n\n",
"It's not. I've never heard anyone call the process of competing their taxes \"paying taxes.\" You file your taxes or you do your taxes.",
"The people you may have heard say that probably know that they underpay their taxes, and will have to write a check after they file their taxes by the mid-April deadline.",
"People don't really say \"paying my taxes\" when referring to that, they usually say \"doing my taxes.\""
]
}
|
[] |
[] |
[
[],
[],
[],
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[],
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|
1m0bud
|
What are the names for the physical aspects of digital memory?
|
I asked this in /r/nostupidquestions but none of the answers I've received actually answered my question.
I'm giving a speech soon on Moore's law for my communications class, and I want to start off with how awesome it is that my little 4GB flash drive the size of my thumb has around thirty-two billion little things in them which hold either a 0 or a 1. I'm studying music, and all of my technical knowledge is amateur at best. Normally I get along quite well but there's an electrical engineer in my class and I don't want him to call me out.
I know at a basic level how digital memory works, but what exactly is the word I want to use for the thirty-two billion little things? Is it silicon? Would it be called a diode? Stuff like that. Thanks!
|
askscience
|
http://www.reddit.com/r/askscience/comments/1m0bud/what_are_the_names_for_the_physical_aspects_of/
|
{
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"text": [
"The RAM in your computer [is made of storage cells (one per bit): one transistor and one capacitor.](_URL_1_)\n\nOTOH, Flash memory is made out of [NAND gates](_URL_0_), with one transistor (more precisely, a [floating-gate MOSFET](_URL_2_)) per bit in high-end SSDs, and one transistor for a couple bits in consumer hardware."
]
}
|
[] |
[] |
[
[
"http://en.wikipedia.org/wiki/Flash_memory#NAND",
"http://en.wikipedia.org/wiki/Dynamic_random_access_memory#Operation_principle",
"http://en.wikipedia.org/wiki/Floating-gate_transistor"
]
] |
|
1pf0w7
|
Why did the US adopt 120v60hz as standard vs the much more widely used 220v50hz that most of the world uses?
|
Title just about sums it up. Is it down to efficiency, ease of delivery, more affordable substations and relays? Enlighten me guys.
|
askscience
|
http://www.reddit.com/r/askscience/comments/1pf0w7/why_did_the_us_adopt_120v60hz_as_standard_vs_the/
|
{
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"text": [
"Remember that big choices about distribution and application (eg choice of drives/machinery) were being made long before digital circuitry. Any basic electrical engineering book can go into detail but some simple dot points:\nFirst on frequency:\n\n* 50Hz may be used in more countries, but that doesn't make it \"more widely used\"\n* 60Hz allowed for simpler analog timing circuits\n* Use of 60Hz leads to less visible flicker, especially during disruptions\n* 50Hz was likely chosen because it's a more round number\n* Higher frequencies mean smaller windings and core materials in transformer construction (fairly advantageous when growing a distribution grid!)\n\nVoltage is a more simple tradeoff (see Ohms Law).\n\n* higher voltages require a little more insulation, but reduce resistive loss\n* for the same amount of power consumed, a higher voltage requires less current, therefore thinner conductors can be used",
"The differences are mainly historical; however, the EU has mandated a standardization of mains at 230V, not 220V. The frequency difference was another historical engineering difference implemented at 60Hz based on Westinghouse generation standard and AEG Germany at 50Hz. US and Euro-based generating companies maintained a unique frequency difference to balance their international monopoly rather than any technical limit as early incandescent bulbs displayed flicker at or below 40Hz which was eliminated at 50Hz. \n_URL_0_"
]
}
|
[] |
[] |
[
[],
[
"http://en.wikipedia.org/wiki/Mains_electricity"
]
] |
|
73au15
|
how come when you stand up on a train you're completely still, but when you stand on a bus you have to hold on to something to stay upright?
|
How come that in certain passenger trains (Such as luxury trains) one is able to stand without falling over, whereas on buses or even other trains one must hold on to something for support?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/73au15/eli5_how_come_when_you_stand_up_on_a_train_youre/
|
{
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"Your body doesn't detect velocity, only change in velocity (acceleration). The reason that you get jostled around is due to a change in your velocity being resisted by your inertia.\n\nTrains tend to move at a constant speed for a long time, typically, as they can go on long stretches of track. Since busses are on a shared roadway with traffic signals and other cars, they have to change their velocity (brake and accelerate) a lot.\n\nTrains are also not able to change their velocity quickly, since their wheels are metal-on-metal which doesn't get as much traction as rubber on asphalt.\n\nBut if your bus goes down a long empty straight with no lights at a constant speed, you could get up and walk without much trouble. Conversely you might fall on your ass if your train brakes super suddenly at the station.",
"Train tracks are generally much smoother than roads. Trains don't do steep hills or sharp corners, so tracks have only very gradual changes in slope or direction.",
"Trains are huge and heavy, unable to speed up or slow down or turn corners rapidly. Buses can do all of these things, which throw you off balance.\n\nIt's these rapid changes in motion, not the original speed of motion, that makes you have to hang on."
]
}
|
[] |
[] |
[
[],
[],
[]
] |
|
tq200
|
Quick question about dog genes
|
When humans inbreed we may have deformaties or mental disablities. I understand dogs have issues with body parts (hips,legs etc).
So say if we hadn't domesticated dogs and inbreed for the best possible genes could dogs have adapted or evolved into an intellectual species that could be equeivelent to humans on an intellectual and or cultural level?
|
askscience
|
http://www.reddit.com/r/askscience/comments/tq200/quick_question_about_dog_genes/
|
{
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"text": [
"If we hadn't domesticated dogs, they would still be wolves."
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|
[] |
[] |
[
[]
] |
|
jajec
|
explain the evolutionary reason for having toes like i'm five.
|
I get the reasons behind most other parts of the body, but I just don't get the point of toes, beside for stubbing.
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/jajec/explain_the_evolutionary_reason_for_having_toes/
|
{
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2,
2
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"text": [
"It adds balance, and originally it was part of our use to hold things with our feet (They where basically like an extra set of hands before we started wearing sandals and whatnot).",
"It adds balance, and originally it was part of our use to hold things with our feet (They where basically like an extra set of hands before we started wearing sandals and whatnot)."
]
}
|
[] |
[] |
[
[],
[]
] |
|
2czzca
|
Does the colour of coffee have any relation to how long it stays hot or it's temperature?
|
I am basing this question around the idea that darker colours absorb more heat.
So, I am wondering, if I were to make two pots of coffee with identical amounts of water but one with a single scoop of coffee and one with two scoops of coffee, would the darker brew stay hotter longer as it is darker in colour?
|
askscience
|
http://www.reddit.com/r/askscience/comments/2czzca/does_the_colour_of_coffee_have_any_relation_to/
|
{
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"cjkqx3o"
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"text": [
"The coffee with two scoops will cool faster, and it has nothing to do with color.\n\nWater has higher heat capacity than coffee, which means that the higher relative water content, the more heat it needs to lose for it to decrease in temperature.\n\n_URL_0_"
]
}
|
[] |
[] |
[
[
"http://en.wikipedia.org/wiki/Heat_capacity"
]
] |
|
3rnnca
|
why is cum white when fresh but clear at room temperature?
|
Curiosity
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/3rnnca/eli5_why_is_cum_white_when_fresh_but_clear_at/
|
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"Real answer: there are enzymes in the semen that digest the fluid to set the sperm free. It goes from white to clear when the digestion is finished. \n\nIt turns out that semen isn't stored anywhere in the body. It's made on the spot when you orgasm by mixing the fluids of several different organs. The sperm cells are kept in a thick gel to protect them, but this also keeps them from moving. When all the ingredients are mixed together during orgasm the enzymes are added to the sperm gel to digest it. \n\nLots of things look \"white\" because there are lots and lots of little particles in the liquid. This is why milk is white! There are lots of protein clumps in the water which scatter the light. When the semen enzymes break down the gel, the liquid becomes clear. This while process is called semen liquifaction. ",
"It's not always white either. The tint fluctuates. Also there can be blood mixed in or blood clot (darker red) mixed in pending the state of the prostate. And surprisingly enough blood in semen is usually benign. ",
"Real question: are you storing your cum?",
"Somewhat related, I had testicular cancer and for a while before I knew I had it but still had the tumor my cum smelled really badly after the tumor came out it returned to a normal odor. What was the tumor doing to make it smell so badly?",
"Why is it so white in porn?",
"As crude as this sounds, it's thicker when fresh so it clings to the recipient's insides and doesn't all fall out almost immediately. It's all about efficient procreation lol.",
"Wait how long do you leave it sitting around?? "
]
}
|
[] |
[] |
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[],
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[],
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|
1qu2id
|
how do voice recognition applications like siri know what we're saying?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1qu2id/eli5_how_do_voice_recognition_applications_like/
|
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"text": [
"First, it cuts the voice recording into really small segments, like 2/100 or 1/100 of a second long. Then, it multiplies each segment by a bell function to get a clear waveform in the middle with reduced interference from neighbouring samples. The waveform of each segment is analysed and compared to waveforms of known sounds. That way, you know which sound was being pronounced during each segment. Remove repeating sounds and you have a basic phonetic spelling of the pronounced phrase. Now you just need some process to match it to a dictionary of known words/phrases, and turn the phonetic spelling into real words.",
"This is a tough one for a 5 year old! But here goes. Speech recognition is an example of computer learning. Lets take our \"supervised learning\" algorithm of choice (LDA, PCA, HMM, Neural Network) and build it so that it knows all the variables in our speech signal. In the case of speech, the most basic variables are frequency and time. So now we have an algorithm that knows about frequency and time, and now we need to teach it how speech changes with frequency and time. So what do we do? We give the algorithm a library of known values - words or syllables, with their corresponding frequency waveforms. So waveform a = Cat, waveform b = Dog, waveform c = Robot. Now we have an algorithm, it has undergone \"supervised learning\" by building the library, and now it is ready to evaluate a new, unknown signal and guess/estimate the word that the signal represents. So! the words you say into the phone are converted into waveforms, then evaluated against the library of known waveforms by the algorithm, and finally Siri responds with her guess of what you said.\n\nAn oversimplification for sure, but I hope it makes some sense!\n",
"Speech recognition is also called speech-to-text. People use both to communicate, but computers aren't like people, so they need a way to \"hear\" the words that are said. \n\nTo \"hear\" the words that are spoken and change them to text, the computer uses a microphone to capture the speech. What is actually happening is that every sound makes a different pattern of sound waves in the air, like ripples on a pond when you throw rocks in. Different patterns of sound waves mean different sounds, and the computer has a list of all the sounds that could possibly be spoken and what letters go with them. When it knows what the letters are, those are spelled out into words, which are written down, and Siri can read them.* \n\n*Siri can't read because she's an idiot who can't even set an alarm right reliably /grumble\n\nTL;DR: Sounds are patterns of waves, and words are patterns of letters. The computer has a model of sounds and a model of words that it thinks it's going to encounter, and it puts these together and picks the right thing. \n\nI have a master's in this stuff, artificial intelligence and language processing, AMAA.\n\nBONUS: \nMe talking about machine translation and how speech recognition is hard: _URL_1_\n\nMe talking about the general gist of text to speech:\n_URL_0_",
"Voice recognition works by breaking up the speech into small segments (phonemes). Each segment is somewhat like a syllable, or a portion of a word, but it is more basic because a couple or a few segments can make up a syllable.\n\nThe segment is compared to the next and/or previous segment and using educated guesses (statistics), the computer can make the best guess of what word was said. \n\nThere is a process of training the computer to recognize the patterns. This involves processing a lot of speech data that has already been processed by a person. Training with your own voice can help the application too.\n\nSo, a large dictionary or knowledge base is searched using best guesses of which segments would follow each other to make up a syllable or word and then which words would make a meaningful sentence."
]
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[] |
[] |
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[],
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"http://www.reddit.com/r/Edinburgh/comments/1cbyuk/do_you_have_10_minutes_to_participate_in_an/c9flsvu",
"http://www.reddit.com/r/MachineLearning/comments/1pvczl/good_universities_for_machine_learning/cd6nhqx"
],
[]
] |
||
1fc0jo
|
Is the sweat produced by exercising different from the sweat produced by sedentary activities e.g. sweating after a shower or sweating in a hot car?
|
askscience
|
http://www.reddit.com/r/askscience/comments/1fc0jo/is_the_sweat_produced_by_exercising_different/
|
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"Also an add on question, if they are different, how do they affect the skin?",
"Hello and welcome to AskScience. Please don't guess the answer.\n\nIt would be useful to find a peer reviewed source that talks about the composition of sweat, and the variation in composition that is possible.",
"The mechanism for sweat production is the same regardless of the activity. Therefore, the ingredients of sweat remain constant, however their precise composition may vary depending on your metabolic rate. Essentially, you have a bunch of ions in your sweat, and, as the sweat is being secreted, they get reabsorbed to create a hypotonic (dilute) liquid. So, sweat starts somewhat concentrated, and becomes more dilute as the ions are reabsorbed by the surrounding sweat gland epithelium on its way out to the skin. This reabsorption alters the concentrations of individual ions, thus producing differences in sweat composition. Therefore, if you sweat a lot (through exercising), or a little (through something sedentary), there will be differences in the composition of your sweat. For example, in response to sympathetic stimulation during exercise, you sweat more. Because your body is pumping out large quantities of sweat very quickly, there's less time for ions to be reabsorbed by your sweat glands, which increases the osmolarity (concentration of ions) within your sweat. On the other hand, if you're only sweating a little bit, the liquid traverses your sweat glands much more slowly, allowing for more reabsorption and thus more dilute sweat. \n\nThe site of secretion is probably more interesting/significant. You have two different types of sweat glands: eccrine and apocrine. The eccrine glands secrete watery sweat and can be found all over your body, and the apocrine glands secrete a more viscous fluid that's largely responsible for the body odor associated with sweating (apocrine glands are found in the armpit and groin, as you may have already suspected).",
"An additional question, linked to this: what sort of sweat therefore is produced during physical exercise done in high heat? Does one take \"precedence\" so to speak? I'm thinking of practices like Bikram yoga or other sorts of hot yoga, for example. ",
"Good question. As with most bodily secretions, the composition of sweat varies depending on its rate of secretion. Without going into too much detail, the initial fluid formed in the sweat glad is filtered from adjacent capillaries, giving it a similar composition to blood plasma. Upon mild stimulation by the sympathetic nervous system, the glands will begin to release the sweat to the skin.\n\nThe interesting part comes in as the sweat is traversing the duct system. The ducts are lined with many different ion channels that act to reabsorb many of the sweat constituents and return them to the lymphatic system. Thus, by the time the sweat from mildly stimulated glands reaches the skin, it has had most of its water, sodium, and chloride reabsorbed, causing the actual sweat to be quite concentrated and composed largely of urea, lactic acid, and potassium.\n\nAs the glands are further stimulated, such as by exercise or heat, the flow rate increases, decreasing the amount of time the initial filtrate is in contact with the ductal ion transporters. In other words, the transporters are overwhelmed by the amount of fluid they have to deal with and are unable to maximally reabsorb sodium, chloride, and water and you release a more dilute sweat containing higher amounts of these ions. Other glands work in a similar fashion\n(if you need a source, Guyton and Hall Textbook of Medical Physiology, 12th ed.)\n\nTLDR: Yes. If you are working hard, your sweat is contains more water, sodium, and chloride. If you aren't, those three substances are highly reabsorbed, leaving a concentrated sweat.",
"Could I add in a third term - what about the sweat induced by stress? Sweating in response to exercise and heat has a clear physiological function; sweating out of stress seems to serve no purpose other than to dehydrate you at a crucial moment.",
"First-year medical student here. The function of sweating, i.e. evaporative heat loss, is the same regardless of what activity, sedentary or active, causes you to sweat. The short answer to your question is: No. \n\nYour sweat is produced by the filtration of your blood plasma (the liquid component of your blood) in the sweat glands in your skin. These glands are located in the dermis, the layer of skin beneath the outermost epidermis. The gland filters almost all of the osmotic proteins present in the plasma out of the \"pre-sweat\" so that your sweat now contains only water, sodium, and chloride (there are trace amounts of other things, like lactate and urea). As the sweat travels through the sweat duct in the epidermis to eventually reach the pores in your skin, the duct reabsorbs about half of the sodium and chloride in the sweat. This is why sweat tastes salty and why it stings your eyes: it's essentially, at a chemical level, salt water. This process is unchanged whether you're sweating after exercise or after a hot shower (which happens to me too, btw). \n\nInterestingly, the chemical composition of your sweat does change if you move to a hotter environment and begin acclimatizing to increased heat. A normal person unacclimatized to increased heat produces (usually) a maximum of one liter of sweat per hour. When a person is exposed to increased heat for several weeks, the body's sweat glands increase their capacity and produce up to 2-3 L of sweat per hour. Sweating more profusely increases the amount of heat removed from the body through evaporation. Simultaneously, the body increases secretion of aldosterone which retains sodium and water in the body and decreases urine output. The concentration of sodium chloride in the sweat also goes down, further increasing retention of the body's electrolytes. A normal person can lose between 15-30 g of salt in their sweat per day, but a person acclimatized to heat for 4-6 weeks only loses around 3-5 g per day. \n\nThe only other instance I can think of in which the sweat changes in composition is in cystic fibrosis. Failure of cellular pumps responsible for reabsorbing chloride results in increased concentration of salt in the sweat of CF patients, in addition to causing a whole host of other problems, notably the buildup of thick mucus in the lungs. \n\nI used Guyton and Hall's Textbook of Medical Physiology, 12 ed., to confirm what I've told you, if anyone has questions about my sources. \n",
"On the topic of sweat: Does the salt content of the sweat vary? Like if you have a lot of salt in your system (say you eat fritos every day) does your body release more salt in sweat?",
"There was a study not too long ago that had people smell sweat that was captured while a person was watching a scary movie and sweat that was captured by the same person watching a pornographic film. People were able to tell which sweat came from which viewing at a statistically significant rate. They also found that couples who had been together for at least a certain time length (I want to say 2 years) were much better at telling which of their partner's sweat went to which viewing.\n\n I realize this doesn't quite answer your question, and I wish I could find the source, but either way I thought it was interesting and at least somewhat relevant."
]
}
|
[] |
[] |
[
[],
[],
[],
[],
[],
[],
[],
[],
[]
] |
||
9w3af1
|
Did the Romans ever use olive oil to fry food?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/9w3af1/did_the_romans_ever_use_olive_oil_to_fry_food/
|
{
"a_id": [
"e9hjvr3"
],
"score": [
80
],
"text": [
"Yes, the cookbook *On Culinary Matters* by Apicius makes frequent reference to frying in oil. You can read it [here](_URL_0_) with pretty copious notes, which are very neccesary given how vague it tends to be.\n\nThis isn't a particularly in depth answer, so I am happy to answer any follow ups."
]
}
|
[] |
[] |
[
[
"http://penelope.uchicago.edu/Thayer/E/Roman/Texts/Apicius/6*.html#IX"
]
] |
||
1ldzee
|
why are some decisions voted on by the people and others just by politicians?
|
I live in Colorado and have voted on the marijuana laws that were put on the ballot. However, recently it was decided that we needed a magazine ban for our rifles (over 15 rounds). Why didn't we get to vote on that? Why are some things up to the people and others seem to be shoved down our throats?
This would apply to both state and federal levels.
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1ldzee/why_are_some_decisions_voted_on_by_the_people_and/
|
{
"a_id": [
"cbya2l9"
],
"score": [
2
],
"text": [
"You have probably heard that the US is a Democratic Republic. This roughly breaks down to mean, that everyone gets to vote (democratic) for representatives who decide laws (republic). \n\nSo in the ideal system, you vote for your representative, congressman or senator, and they vote on all issues for you.\n\nThe idea is that it's unreasonable to expect every person to be up to date on every issue. Instead we have representatives who don't have a normal job so they can be up to date on every issue and thus have educated opinions.\n\nSometimes issues are taken directly to the people. Most commonly this is by propositions. The original point of propositions was that if the people want something (eg -legalized marijuana) and for whatever reason the representatives won't pass it, then the people would be able to directly vote it into law.\n\nTheoretically propositions should be unnecessary because the representatives should be representing the will of the people but obviously this is not always the case."
]
}
|
[] |
[] |
[
[]
] |
|
1l5lua
|
Why were the designs for nuclear weapons declassified?
|
I know there are not detailed schematics or anything (as far as I know) but today I can go on Wikipedia and find a diagram of Fat Man and Little Boy, along with both modern fusion and fission bombs. When were the workings of th bomb made public and, maybe more importantly, Why?
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/1l5lua/why_were_the_designs_for_nuclear_weapons/
|
{
"a_id": [
"cbw1j88"
],
"score": [
5
],
"text": [
"The answer to this could be quite long, because there are multiple levels of information in question. Here's a summary of the basic concepts (I can elaborate on any of these at length):\n\n* The very basic idea of the gun-type weapon was first released in the Smyth Report (1945), only a few days after the bombing of Nagasaki, because it was obvious. It was also somewhat misleading, because by the time of the Trinity test it was basically obsolete.\n\n* The basic idea of implosion was declassified in 1951, [in order to be used as evidence in the Rosenberg trial](_URL_2_). By that time, the USSR had the bomb so it was considered declassifiable. (They were not yet worried about broader proliferation at this point, and did not consider the basic idea of implosion a major difficulty in getting the bomb anyway.)\n\n* Many details of fission technology were declassified in the 1950s as part of the push for civilian nuclear power, and distributed worldwide as part of the Atoms for Peace program. These were not largely specifically about bombs, per se, but there is a wide area of overlap. Many technologies relating to fissile material production (nuclear reactors and electromagnetic separation plants, for example) were declassified during this period as well. \n\n* The ballistic casings of the Little Boy and Fat Man bombs were declassified in 1960. Just included to give you an idea of how long it took before even these very basic facts were released. The delay was not for any particular reason by that point.\n\n* The fact that H-bombs could be made, and had a final \"fission\" stage, was known by 1954, after the Castle Bravo accident. Many independent researchers were able to deduce the final fission stage from public accounts of the accident. Many of the basics of the Teller-Ulam design, though, were still not publicly known or only murkily known and mixed in amongst other (incorrect) speculation.\n\n* In 1979, an activist named Howard Morland attempted to publish his notion of how an H-bomb worked in the magazine _The Progressive_. The government took him to court to try and stop him (the only time they have tried to do this with regards to privately-generated nuclear bomb diagrams). The end result was that a lot of new information was inadvertently released as part of the judicial process, and in the end the government found an excuse to moot the case just before the appeals court was likely to overturn the Atomic Energy Act. _The Progressive_ published Morland's article to some fanfare, and the fact that the government tried to censor it gave it legitimacy.\n\n* Many more details about how H-bombs work were released in the mid-1990s as part of the declassification of the field of inertial confinement fusion. It shares many similar physical properties with H-bombs (which is why it was classified until this point). It was declassified with the idea of possibly creating a new power source.\n\n* The more advanced Teller-Ulam ideas (non-spherical primaries and spherical secondaries) were released in 1999 as part of the reportage on the Wen Ho Lee scandal.\n\n* For a wide variety of reasons the US government has dribbled out information [over the years](_URL_1_) regarding previously-classified concepts, some of which, in the right interpretive hands, have relevance to specific weapons designs. The reasons include: the private development of civilian power; the encouragement of the development of fusion research; facts related to weapons safety, health issues, and civil defense; information that becomes widely-known due to leaks or independent rediscovery; information necessary for explaining major public relations issues to the public.\n\n* There have been sub-communities of private researchers attempting to ferret out information about the details of all nuclear weapons since the 1970s. Among these have been the activist Morland (previously mentioned) and the late Chuck Hansen. Their tools include talking with weapons scientists, using the Freedom of Information Act, their own calculations and theories, and even snaking cameras into historical bomb casings on display at museums. They have tried to piece the above-mentioned collection of declassified facts, plus rumors, leaks, and accidental disclosures, into coherent ideas about weapons design. \n\nThis final category is where those diagrams on the Wikipedia pages come from. The Little Boy bomb diagram, for example, is more or less the creation of a guy named John Coster-Mullen, who has spent many years trying to locate every nut, bold, and washer on the Little Boy bomb, drawing on vast stores of declassified documents and interviews with Manhattan Project participants. [He has written a self-published book](_URL_0_) outlining the technical details, with extensive documents and footnotes explaining where he got them from. (His major coup was discovering that the Little Boy bomb's assembly mechanism is not a small projectile of U-235 shot into big target of U-235, but a large projectile shot into a small target. This may seem like a minor point but somehow every previous researcher missed it. I've become completely convinced that John is correct on this point.)\n\nThere's a lot more where this came from, but perhaps this gives some indication. There are only a few \"big releases,\" noted above, but a wide variety of \"smaller\" releases, plus a lot of speculation."
]
}
|
[] |
[] |
[
[
"http://www.amazon.com/gp/product/B0006S2AJ0/ref=as_li_qf_sp_asin_il_tl?ie=UTF8&camp=1789&creative=9325&creativeASIN=B0006S2AJ0&linkCode=as2&tag=000000123-20",
"http://www.fas.org/sgp/othergov/doe/rdd-8.pdf",
"http://atomlandonmars.com/greenglass-secret-of-the-atomic-bomb.html"
]
] |
|
3tlt4m
|
why can't tyres be recycled into more tyres? i always see tyre graveyards where they are just left to rot or they are burned.
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/3tlt4m/eli5_why_cant_tyres_be_recycled_into_more_tyres_i/
|
{
"a_id": [
"cx78m16",
"cx797ir"
],
"score": [
5,
2
],
"text": [
"They can be recycled. You can convert them back into a more suitable base synthetic rubber that you can use for a variety of things like more tires. The problem is that this is a generally prohibitively expensive thing to do -- it's cheaper just to make new tires.\n\nTires are also combustable, which means they can and are used as fuel. While not necessarily good for the atmosphere, the EPA estimates about 45% of all used tires in the US are used to produce energy.\n\n[This is a good article](_URL_0_) that talks about these things including the source for the EPA estimate.\n\nEDIT: A good note is that recycling tires is growing fairly quick and there are entire companies that specialize in recycling tire mountains.",
"I have been told, true?, that they make the rubber tracks for high schools out of them. They can be shredded and mixed with asphalt to pave roads."
]
}
|
[] |
[] |
[
[
"http://www.earth911.com/living-well-being/travel-living/recycling-mysteries-tires/"
],
[]
] |
||
byqeid
|
why is the portuguese man o' war and other siphonophore considered to be a colony of different organisms if they all have the same dna? wouldn't zooids just be concidered organs?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/byqeid/eli5_why_is_the_portuguese_man_o_war_and_other/
|
{
"a_id": [
"eqlizsf"
],
"score": [
2
],
"text": [
"Its like bacteria that can reproduce asexually by splitting themselves. The 2 new bacteria are seperate, but share their dna. \n\nSimilarly, it can br thought of like cloning. If you clone a person, they will be 2 seperate people, but share the same dna. \n\nSo it is a city of clones that beocme specialized to do certain tasks. Some of the clones control breathing, some digestion, etc."
]
}
|
[] |
[] |
[
[]
] |
||
4979qd
|
Why wasn't the German Empire partitioned like the Austro-Hungarians after WW1?
|
After WW1 the Austro-Hungarian Empire was divided up to the point of irrelevancy.
The Germans however got to keep most of their land apart from some Polish/Baltic holdings.
Especially considering the nation was still very young it is strange that the allies kept it mostly intact and instead burdended it with massive debts that would inevitably anger this still powerful country.
Was splitting it up considered by the Allies?
(In states like Prussia/Rheinland/Bavaria)
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/4979qd/why_wasnt_the_german_empire_partitioned_like_the/
|
{
"a_id": [
"d0pynn0"
],
"score": [
2
],
"text": [
"Germany was ethnically and religiously more unified. Germans were generally Catholic, Protestant, or Jewish and all of these people spoke German as their primary language, or Yiddish, which is partly based in German (and whose speakers were generally bilingual). This population thought of itself as German, though much of it in some parts were Germanized Slavs or Balts. Politically, they also in general saw themselves as heirs of the Holy Roman Empire, which was politically dominated by Germans during its history. \n\nThe biggest area where this was not true was in the Polish Corridor, which was carved out to give a resuscitated Poland access to the sea, including many who identified themselves as Polish. \n\nGermany's impetus toward unity in later years sewed East & West Germany back into one nation. \n\nThat unity was never natural to Austria-Hungary. Austria-Hungary was radically different. It included Catholics, Protestants, Jews, and Muslims, Eastern Christian rites, and a huge assortment of ethnic groups.\n\nThe Hungarians and other groups hankered for their own nation; Magyars saw themselves as a distinct group, as did the others. Ethnically, Austria-Hungary included Czechs, Magyars, Germans, Croats, Romanians, Serbs, Slovaks, Slovenes, Jews, Poles, Ukrainians, Bosniaks, etc. \n\nIt was just too diverse, in the face of nationalism, to stay together as one entity after the monarch fell from power. Not even Yugoslavia, which included some of its lands, was able to last after the death of Tito. "
]
}
|
[] |
[] |
[
[]
] |
|
8edw3n
|
difference between probiotics and prebiotics
|
Edit: I actually went in the search bar and answered the question myself through reading.
How do prebiotics work though?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/8edw3n/eli5_difference_between_probiotics_and_prebiotics/
|
{
"a_id": [
"dxuecar"
],
"score": [
8
],
"text": [
"Prebiotics are essentially food for probiotics. The way they work is that the probiotics, which boost immunity and general health, mainly for the GI. The probiotics feed on the prebiotics, so they will be able to do what I listed above better.\n\n[Source](_URL_0_) in case I missed anything"
]
}
|
[] |
[] |
[
[
"https://www.eatright.org/food/vitamins-and-supplements/nutrient-rich-foods/prebiotics-and-probiotics-creating-a-healthier-you"
]
] |
|
4avezp
|
Can people with lazy eye choose which eye to use and alternate between them?
|
[deleted]
|
askscience
|
https://www.reddit.com/r/askscience/comments/4avezp/can_people_with_lazy_eye_choose_which_eye_to_use/
|
{
"a_id": [
"d142kwc"
],
"score": [
5
],
"text": [
"Optometrist here. The answer is \"sometimes,\" and \"it depends.\"\n\n\"Lazy eye\" means many different things to different people. The clinical definition of lazy eye, or \"amblyopia\" is an eye with reduced vision not due to any organic cause. Basically it is a healthy eye, but due to hindered development, does not see well, even with corrective lenses. This has many causes, a very common one being \"strabismus,\" or an eye turn. \n\nWhen your average joe refers to a lazy eye, they are usually (and technically incorrectly) referring to an eye turn (strabismus) specifically, not the visual reduction itself.\n\nHowever, to answer the question as I believe it was intended: there are many kinds of strabismus, defined by the eye, direction of the turn, and frequency. Usually inward eye turns are more severe and more difficult for the individual to notice or control. Outward turns usually have a better visual prognosis. They are also much more likely to alternate between the eyes (that is, sometimes left eye turns, sometimes right eye). It is these alternating outward turns that can sometimes be controlled directly by the individual when they think about it.\n\nSo, to sum up: not usually, but sometime yes, it's possible. It depends on the case."
]
}
|
[] |
[] |
[
[]
] |
|
3qu80x
|
Did traditional pike and shot armies ever fight all infantry or all cavalry armies in the open field?
|
I've read about the clashes between pike and shot armies in Europe throughout the Thirty Years War etc, but did they face other opponents?
By all-infantry I mean something like a native American force (which I know the Spanish encountered, but I'm not sure how they dealt with them) and by all-cavalry I mean something like a Mongol horse archer army.
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/3qu80x/did_traditional_pike_and_shot_armies_ever_fight/
|
{
"a_id": [
"cwiff4p",
"cwiqelc"
],
"score": [
15,
6
],
"text": [
" > native American force\n\nNeither the Spanish nor other European powers ever sent an army to the Americas in the initial stages of conquest. \n\n > Mongol horse archer army\n\nNo. \n\n > Did traditional pike and shot armies ever fight all infantry or all cavalry armies in the open field?\n\nThe closest was probably during the Hussite wars (1460s-1460s), although it was a bit too early for the early-modern pike and shot. The Hussites had a mostly peasant infantry, but they still had pikes, firearms. They had little to no cavalry. They faced a composite crusaders' army with heavy calvalry and also other arms. \n\nTo overcome their deficiency in cavalry, the Hussites developed a circle-the-wagons strategy to be able to fight in relatively open fields. \n\nBy this point, it was already known that combined arms are a powerful concept and nobody willingly fought in handicap fashion.",
"In the case of the New World conquest, although some members of the expeditions had certainly fought in the Italian Wars (1494-1504) where pike/shot/word formations were utilized by Gonzalo Fernandez de Cordoba against the French, the expeditionary forces did not really fight in a pike and shot formation. It appears from Diaz del Castillo's account of the conquest of Mexico that most of the soldiers were armed with swords and shields. At that point in the early 1520s swordsmen were still a part of Spanish formations, which would become known as the tercio. And of course, pikes don't really work when you only have a few hundred men and are frequently surrounded by enemies, so having what I will call a \"sword and shot\" formation was more useful. \n\nAs for cavalry vs. pike and shot, I don't know of any wholly cavalry armies that attacked pike and shot formations, but mounted elements of an army certainly have, without being supported by infantry or artillery. In short, these cavalry charges have not gone well, cavalry after the reemergence of pike formations in the 15th century cannot generally take on infantry from the front, and need to be used against demoralized troops of from the flanks. (all of these examples happen to do with the French because I like French failures as a Spanish historian)\n\nBattle of Cerinola (1503)- French cavalry under the Duke of Nemours charge towards a thin line of fortified arquebusiers backed up by pike formations. The charge is stopped by shot and the ditches, and then the pikemen advance and push the cavalry off the field. Not an open field but it was a field battle with hastily erected defenses, which was one of Fernandez de Cordoba's trademarks. \n\nBattle of Pavia (1525)- King Francis charges ahead of his infantry support with his heavy cavalry, but is essentially ambushed by pike and shot elements coming out of the woods from all directions, he is captured and many of his knights are killed.\n\nBattle of Waterloo (1815)- Pike and shot has been combined by giving everyone bayonets- Marshal Ney charges with 9,000 cavalry at Wellington's cannons and infantry. They overrun the cannons but the Brits fall into battalion sized square formations and repel repeated assaults. \n"
]
}
|
[] |
[] |
[
[],
[]
] |
|
4vuz7w
|
Astrophysics: Is there a practical reason to build a particle accelerator in space?
|
I was watching an episode of dark matter and they came across a research station that had a particle accelerator like the LhC built around it. I was wondering would there be any scientific is astronomy reason to do so?
Astronomy
|
askscience
|
https://www.reddit.com/r/askscience/comments/4vuz7w/astrophysics_is_there_a_practical_reason_to_build/
|
{
"a_id": [
"d621d7u"
],
"score": [
4
],
"text": [
"not really astronomy, but building in weightlessness confers the advantage that the components aren't limited by their own weight. If you've seen pictures of the LHC as it was being built you can see huge support structures for the various parts. Being in low-gravity makes the engineering much simpler and thus we can build even bigger accelerators and more powerful accelerators.\n\nSecond, space has no air. A lot of effort is spent in the LHC to create particle physics quality vacuum (which is the deepest vacuum grade you can get on earth). This is necessary because as the particles travel around the accelerator if they hit an air molecule they fly off course and loose energy. With a great vacuum already provided in space we can chuck out a lot of machinery just to keep the accelerator evacuated. Heck we could even build an open-space accelerator where the particle beams aren't even enclosed, they would just travel through space from magnet to magnet without worrying about hitting anything. \n\nThird, space is cold, very cold. And with some very easy reflectors and light shields to block the sun we can get to very low temperatures very easily. A huge amount of the LHC power bill comes from just running the refrigerators and cryogenic systems. The LHC has to be so cold because it uses superconducting wires for its magnets and these only work at very cold cryogenic temperatures. Just starting it up after maintenance runs and cooling it back down to operating temperature takes weeks and thousands of tons of liquid nitrogen. If we could build it in space we wouldn't have these issues and can build even bigger and stronger magnets since we don't need to waste space with cooling systems. Also, the detectors and sensors that actually do the physics also require ultra-cold temperatures. We'd probably still need cooling systems for them in space (since the sensors actually run *colder* than outer space) but the requirements and complexity would be much less since we don't have to fight a temperature of room temperature down to near absolute zero. Being already near absolute zero makes the difference much easier to handle.\n\nThere are some disadvantages of space though.\n\nThe major one i can think of is radiation. Cosmic radiation would constantly rip through the accelerator and mess up the sensors. This is why the LHC is built underground. The overhead rock blocks a good portion of the cosmic rays so the LHC can focus on itself. If we built in space, we'd have to sift out the extraneous events in the data coming from the sensors, or we would have to bring huge amounts of shielding metal into space to protect the detectors. I'm not sure what the better solution would be. Another issue with radiation is that our \"super-accelerator in space\" would logically need superior computing power to sift through the petabytes per second of data that comes from the detectors. Radiation already causes issues with computers in data centers on earth. It would be a nightmare to bring such sensitive computers into space.\n\nThen there are the usual issues of cost, logistics, attack by space aliens, but i won't get into those since they're the same for every other space project. \n\n\n\n"
]
}
|
[] |
[] |
[
[]
] |
|
1z1kl6
|
why is uganda so anti gay?
|
Is it something inherent in their culture/African culture? Or are they just anti western? Because I see some statements in their news condemning the West for trying to recruit people into "homosexual" organizations?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1z1kl6/eli5why_is_uganda_so_anti_gay/
|
{
"a_id": [
"cfpoauu",
"cfporx1",
"cfpsf1p"
],
"score": [
2,
2,
2
],
"text": [
"It's cultural. They seeme to be very conservative, probably to the point of making Tea Partiers look like bleeding heart liberals. They don't seem to be \"anti-Western\" in the sense that they are doing it to rebel against Western pressure.",
"Because Fundamentalist Christians from the US realized that they had lost the culture wars here and went to Uganda in order to promote anti-gay legislation.\n\nThey are literally pushing murder in the name of Jesus.",
"It's a complicated issue. But here are two major but not-so-obvious factors:\n\n1) Ugandans, like much of the world that was once colonized by the west, are concerned with protecting their society from excessive cultural influence by the west (aka cultural imperialism). Because many western societies have moved toward protecting/supporting/embracing LGBT people in recent years, there is a perception by the anti-gay camp that LGBT sexuality is a lifestyle choice that western society invented and is trying to export, rather than something intrinsic to Ugandan people. As such, they claim that homosexuality is \"un-African\".\n\n2) Some Christian fundamentalist organizations from the USA are heavily supporting the anti-gay movement in Uganda (though not necessarily the anti-gay law as written).\n\nAs you can see, the Ugandan anti-gay movement isn't completely pro- or anti-western, but has elements of both. One could argue that they are pro-western when it suits their interests (my personal view), but then we'd be getting into opinion.\n"
]
}
|
[] |
[] |
[
[],
[],
[]
] |
|
m8fd2
|
Nutritionally speaking, is the crust really the best part of bread or were my parents lying to me throughout my childhood?
|
askscience
|
http://www.reddit.com/r/askscience/comments/m8fd2/nutritionally_speaking_is_the_crust_really_the/
|
{
"a_id": [
"c2yys2a",
"c2yys2a"
],
"score": [
4,
4
],
"text": [
"Amino acids are consumed during the Maillard reactions that brown the crust of your bread, and the resulting reaction products are not nutritionally relevant. So strictly speaking, the crust is less nutritious than the crumb.",
"Amino acids are consumed during the Maillard reactions that brown the crust of your bread, and the resulting reaction products are not nutritionally relevant. So strictly speaking, the crust is less nutritious than the crumb."
]
}
|
[] |
[] |
[
[],
[]
] |
||
lxwhp
|
how to properly do laundry.
|
I've never been able to confront this because of the sheer risk of ruining my clothes. But the time has come and I MUST learn. I've read some articles online, but none have really helped.
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/lxwhp/eli5_how_to_properly_do_laundry/
|
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"1) Sort clothes by light and dark.\n\n2) Put clothes in washer with soap.\n\n3) Turn on washer (use cold water).\n\n4) When washer finishes, immediately put in dryer.\n\n5) Turn on dryer (use low heat, but not fluff).\n\n6) When dryer finishes, immediately remove and fold.",
"Assuming you know how to physically work a washer and dryer, it's more about what you *don't* do.\n\n* Don't combine deep or bright colors (reds in particular) with whites or light colors, or they'll bleed and ruin your whites. Combining different dark colors (a dark red and a dark blue shirt, for instance) is generally fine.\n\n* Hotter water gets your clothes cleaner but makes the colors more likely to bleed. Personally, the only clothes I wash in hot water are socks and white undershirts (in the same load) and jeans. Stick with cold water for anything made of wool, anything with both light and dark colors (striped shirt, for instance), and delicates. Warm is fine for just about anything else.\n\n* Hang up sweaters and delicates to dry if possible; if not, dry with low or no heat. Medium heat is fine for anything else. Keep the lint trap (usually just inside the door near the bottom) as clean as possible.",
"OK, most posts are helpful but IMHO not complete. \n\nYou need a washing machine and knowledge of 2 main settings:\n\n* The first is a low temperature wash used for colours and delicate items. This is normally around 30-40 degree Celsius (about 100 Fahrenheit). \n\n* The second is a high temperature wash used for white items and light bed linen. The hot temperatures help to get the bright white back and kill any bed bugs. This can be up to 90 degrees Celsius (about 180 Fahrenheit) but causes clothes to wear out quicker.\n\nYou will need washing powder. Some are tablets, some you put in a ball which goes in the tumbler, some are just plain powders. I use powder as it's cheap and easy (like me):\n\n* Biological Washing powder - Powerful cleaning enzymes so good for heavy stains. Bad though as it will cause colours to fade quicker, worse for the environment and some people can have allergic reactions.\n\n* Non-Biological power - More gentle on clothes, better for allergic types, environmentally friendly(ish), though not as powerful.\n\nOptional:\n\n* Fabric softener - This is a liquid that you pour into a special drawer/compartment of the washer. The machine puts this in after the wash so your clothes come out smelling lovely and feel softer to the touch. Don't know how, it's just magic. Great for shirts making them easier to iron.\n\n* Stain remover - These are often course powders that you can buy separately and contain powerful cleaning agents. Use sparingly.\n\n**Step 1** - Sort your clothes into a colours pile and light/white items pile. Be careful with items that are white but have coloured parts/patterns. If in doubt chuck it in the colours pile.\n\n**Step 2** - Put your selected pile of colours or whites in the machine. Check the setting: hot for whites, cool for colours. Put the washing powder and stain remover in together, fabric softener goes in a separate compartment. Double check the setting!\n\n**Step 3** - When the wash cycle is finished you want to decide where they go next sooner rather than later. If you leave wet clothes in the drum for a couple of days they go stale. \nIf you want soft fluffy towels/bedding/underwear put them in a tumble dryer. \nIf not save yourself the electricity and hang them up. It's important not to tumble dry shirts as they become a nightmare to iron! Hang them up whilst still wet!\n\n\n\n",
"1) Sort clothes by light and dark.\n\n2) Put clothes in washer with soap.\n\n3) Turn on washer (use cold water).\n\n4) When washer finishes, immediately put in dryer.\n\n5) Turn on dryer (use low heat, but not fluff).\n\n6) When dryer finishes, immediately remove and fold.",
"Assuming you know how to physically work a washer and dryer, it's more about what you *don't* do.\n\n* Don't combine deep or bright colors (reds in particular) with whites or light colors, or they'll bleed and ruin your whites. Combining different dark colors (a dark red and a dark blue shirt, for instance) is generally fine.\n\n* Hotter water gets your clothes cleaner but makes the colors more likely to bleed. Personally, the only clothes I wash in hot water are socks and white undershirts (in the same load) and jeans. Stick with cold water for anything made of wool, anything with both light and dark colors (striped shirt, for instance), and delicates. Warm is fine for just about anything else.\n\n* Hang up sweaters and delicates to dry if possible; if not, dry with low or no heat. Medium heat is fine for anything else. Keep the lint trap (usually just inside the door near the bottom) as clean as possible.",
"OK, most posts are helpful but IMHO not complete. \n\nYou need a washing machine and knowledge of 2 main settings:\n\n* The first is a low temperature wash used for colours and delicate items. This is normally around 30-40 degree Celsius (about 100 Fahrenheit). \n\n* The second is a high temperature wash used for white items and light bed linen. The hot temperatures help to get the bright white back and kill any bed bugs. This can be up to 90 degrees Celsius (about 180 Fahrenheit) but causes clothes to wear out quicker.\n\nYou will need washing powder. Some are tablets, some you put in a ball which goes in the tumbler, some are just plain powders. I use powder as it's cheap and easy (like me):\n\n* Biological Washing powder - Powerful cleaning enzymes so good for heavy stains. Bad though as it will cause colours to fade quicker, worse for the environment and some people can have allergic reactions.\n\n* Non-Biological power - More gentle on clothes, better for allergic types, environmentally friendly(ish), though not as powerful.\n\nOptional:\n\n* Fabric softener - This is a liquid that you pour into a special drawer/compartment of the washer. The machine puts this in after the wash so your clothes come out smelling lovely and feel softer to the touch. Don't know how, it's just magic. Great for shirts making them easier to iron.\n\n* Stain remover - These are often course powders that you can buy separately and contain powerful cleaning agents. Use sparingly.\n\n**Step 1** - Sort your clothes into a colours pile and light/white items pile. Be careful with items that are white but have coloured parts/patterns. If in doubt chuck it in the colours pile.\n\n**Step 2** - Put your selected pile of colours or whites in the machine. Check the setting: hot for whites, cool for colours. Put the washing powder and stain remover in together, fabric softener goes in a separate compartment. Double check the setting!\n\n**Step 3** - When the wash cycle is finished you want to decide where they go next sooner rather than later. If you leave wet clothes in the drum for a couple of days they go stale. \nIf you want soft fluffy towels/bedding/underwear put them in a tumble dryer. \nIf not save yourself the electricity and hang them up. It's important not to tumble dry shirts as they become a nightmare to iron! Hang them up whilst still wet!\n\n\n\n"
]
}
|
[] |
[] |
[
[],
[],
[],
[],
[],
[]
] |
|
2uz0ig
|
if a pilot crashes a plane due to a mechanical failure and crash lands into some number of people, killing them, who is at fault?
|
Let's assume he chose the group of people because he felt that it would cause the least amount of deaths.
Edit: I'm curious cuz the pilot has (some) control over the plane until it inevitably crashes. Who would be blamed for those deaths?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/2uz0ig/eli5if_a_pilot_crashes_a_plane_due_to_a/
|
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"Well, 'mechanical failure' excludes the pilot entirely.\n\nNow, it's up to the National Transportation Safety Board. (NTSB) or equivalent agencies to investigate and determine whether it's the maintenance (airlines, military branch, or private operator) at fault, or the manufacturer (who built the plane(Boeing, Lockheed, Airbus, Cessna), etc.).\n\nThey do this by collecting every piece of the plane after it crashes, and look for anything out of order for any reason not caused by the crash itself. \n\nFor example: if they find a segment of hydraulic line with a leak in it, enclosed in an unaffected segment of wing, then good chance is that's at fault.\n\nThey then look at the maintenance logs, and see if it was checked and replaced as frequently as it needed to be. If not, maintenance at fault. If it is, they look to see if it's happened more than once, indicating a substandard grade element used in the manufacture, or if only once- more likely a defect made by the manufacturer or subcontractor.\n\nIf it's a defect, covered by relevant insurance, if substandard element- planes retrofitted with better alternative, victim payout comes out of general liability insurance.",
"Depends if he flew for a company, if his plane was up-to-date service wise, if the mechanic servicing the plane had enough rest, etc. Rarely in these cases does the blame land on the pilot, more likely on the company for some level of gross negligence. ",
"No easy answer. Why did the mechanical failure occur?\n\nDid he know it was a possible problem when he took off?\n\nDid he say anything to the airline supervision, or if it's a private plane, is he the owner? Did he say something to the owner? \n\nWhat were his reasons for taking off in a plane that had a problem? \n\n\nDid he complete the ENTIRE pre-flight checklist? \n\n\nI could keep going! \n\n\nThe answer is almost never simple. \n\n",
"Well from my **biased** perspective as aircraft maintainer, investigators will *always* try to pin blame on maintenance. Its a really scary place to work when a plane goes down. Without a word, suits show up, confiscate log books, isolate and interview people, and scrutinize our records to death. Not only that, all the folks in the section then get piss tested for drugs, whether you worked on that plane or not.\n\nThe thing is, pilots are the face of aviation. The public places a huge amount of trust in a pilot when they board a plane. Because of this, pilots are given quite a large benefit of doubt, even though most aviation accidents are directly caused by pilot error. That trust needs to be maintained if people want to feel safe flying. The maintainer side of aviation acts as the scapegoat. The investigators try to find any teeny tiny mistake in the system so they have an excuse to roll the whole thing up and drop it in maintenance's lap.",
"I really recommend watching Air Crash Investigation/Mayday, if you are interested in such. It's a really in-depth series with reconstructions of air crashes/emergencies with an investigation. The pilots in the reconstruction are very accurate and use the actual Cockpit Voice Recorder recordings to say everything the pilots actually said. If there are any survivors, they are interviewed.\n\nBasically, nothing is made up, and it's accurate.\n\nIt airs on National Geographic and Smithsonian Channel, I believe."
]
}
|
[] |
[] |
[
[],
[],
[],
[],
[]
] |
|
2r0j93
|
How does an Analog-to-Digital converter work ?
|
askscience
|
http://www.reddit.com/r/askscience/comments/2r0j93/how_does_an_analogtodigital_converter_work/
|
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"There's more than one type of ADC. Common types are SAR, flash, and delta-sigma.\n\nA SAR ADC (essentially) ramps up a voltage using a binary counter until the voltage exceeds the sample voltage. Imagine turning up a dial, then reading the dial when a light comes on and reporting the value. SAR stands for Successive Approximate Register--the ADC creates Successive Approximations, then reports the one that worked best. SAR ADCs are very common; if you use an Arduino, for instance, the ADC in there is a SAR.\n\nA Flash ADC has some number of reference voltages and reports which one works best. It's *super* fast, but also very large in terms of silicon space, since you need (e.g.) 256 comparators and voltage references for an 8-bit ADC.\n\nBoth of those are fundamentally pretty similar--figure out which of a group of known voltages is closest to the unknown and express that as a binary value. Delta-sigma is harder, and you need some signal analysis knowledge to grok it. Check out the [Wikipedia article](_URL_0_).\n\nRegardless of the method you use, the result is reported as a fixed-precision unsigned binary number, which can best be understood as a percentage of the whole range times the global reference voltage. For instance, a 10-bit ADC has (about) 1000 steps, and with a 5V reference, each step (frequently called an LSB, or least significant bit) is about 4mV. Thus, a reading of 250 from a 10-bit ADC in a 5V system represents about a 1V signal."
]
}
|
[] |
[] |
[
[
"http://en.wikipedia.org/wiki/Delta-sigma_modulation"
]
] |
||
1m0j69
|
why do some people walk on their tippy-toes?
|
as compared to the normal/standard heel, sole, toe? Is it genetics or just how they learned? Are there any side effects?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1m0j69/eli5_why_do_some_people_walk_on_their_tippytoes/
|
{
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"text": [
"Personally, because I grew up in and live in a house with raised timber floors. Clumping through it with a heel-toe walking style makes too much noise and would shake things off shelves."
]
}
|
[] |
[] |
[
[]
] |
|
we91s
|
Is there a beginning of time?
|
askscience
|
http://www.reddit.com/r/askscience/comments/we91s/is_there_a_beginning_of_time/
|
{
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"text": [
"We are not exactly sure when our idea of time began but the common theory is that time began when the Big Bang happened. Therefore you could consider the beginning of time to be the creation of the universe.\n\n\n[From the time wiki:](_URL_0_)\n > Stephen Hawking in particular has addressed a connection between time and the Big Bang. In A Brief History of Time and elsewhere, Hawking says that even if time did not begin with the Big Bang and there were another time frame before the Big Bang, no information from events then would be accessible to us, and nothing that happened then would have any effect upon the present time-frame.[56] Upon occasion, Hawking has stated that time actually began with the Big Bang, and that questions about what happened before the Big Bang are meaningless.[57][58][59] This less-nuanced, but commonly repeated formulation has received criticisms from philosophers such as Aristotelian philosopher Mortimer J. Adler.[60][61]\nScientists have come to some agreement on descriptions of events that happened 10−35 seconds after the Big Bang, but generally agree that descriptions about what happened before one Planck time (5 × 10−44 seconds) after the Big Bang are likely to remain pure speculation.\n\n"
]
}
|
[] |
[] |
[
[
"http://en.wikipedia.org/wiki/Time#Time_and_the_Big_Bang"
]
] |
||
1v9tur
|
I saw earlier in /r/todayilearned that there's a giant space cloud composed of water vapor. Is it possible that this will eventually form planets made exclusively of water?
|
If so, if it was the size of Earth or bigger, what would the core of a water only earth-sized planet be like? Would the water just solidify due to the immense pressure and essentially have a hot ice core? At what depth would the phase change (if any) occur?
|
askscience
|
http://www.reddit.com/r/askscience/comments/1v9tur/i_saw_earlier_in_rtodayilearned_that_theres_a/
|
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"text": [
"I wonder. Is there a possibility that the H2O could separate and the planet would form in layers?\n\nAssuming that there is enough substance of course.",
"I wonder why scientists NEVER mention the possibility of the earth (never in the same point in outer space twice) passing through a GIANT cloud/region of poisonous/toxic/corrosive/explosive material/vapor/gas/particles.\n\nThey mention asteroids, gamma bursts and such, why don't they EVER mention things like clouds?",
"[This paper](_URL_0_) (pdf) by Leger et al. covers most aspects of what a possible ocean planet might be like, including a section on the internal structure. I'm sure I've seen a more detailed paper that covers ice planet structures for a variety of different cases, which had some interesting bits on different types of ice forming in consecutive layers, but none of the papers I have on planetary structures are the right one. I'll keep looking for it when I get some free time.\n\nEdit: It should be noted that this could won't be composed entirely of water vapour - whilst I don't have the source, what it likely said is that it's unusually rich in water. Molecular clouds in space are composed almost entirely of Hydrogen and Helium, with trace amounts of basic compounds like water, and a small amount of \"dust\" formed of things such as grains of carbon or silicates.",
"_URL_0_ is a diagram of the phases of water. Above a certain pressure room temperature ice exists (roughly 600mpa).\n\nThe chart only goes to 350*C and it's reasonable to assume that the core of a water planet might be warmer than that, and I'm not sure what would happen beyond that.",
"This cloud has a lot of water vapour in it, but it is still almost entirely Hydrogen gas. According to the paper, the ratio of H20 to H2 is 1.4x10^-7 . That means the cloud is something like .00001% water.\n\n[This is the paper](_URL_0_)"
]
}
|
[] |
[] |
[
[],
[],
[
"http://cips.berkeley.edu/events/seminars2005_2006/leger.pdf"
],
[
"http://upload.wikimedia.org/wikipedia/commons/0/08/Phase_diagram_of_water.svg"
],
[
"http://arxiv.org/pdf/1106.4301v2.pdf"
]
] |
|
2a55kf
|
how do workers build buildings and structures without holding any manuals or instructions?
|
When I build something from IKEA, for example, there are a billion steps that I follow by looking at a guide. I never see workers out there with even a scrape of paper that lists the measurements between walls etc. How do they know just what to build and what the architect's desired steps are? I'm sure the docs are in the foreman's office but don't the workers need to hold something while they work? They can't all have perfect memories.
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/2a55kf/eli5_how_do_workers_build_buildings_and/
|
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"Blueprints exist and building plans exist.\n\nAlso adding 1 or 2 parts takes a several man crew. They also are step-by-step instructions because the engineers assume the people who build stuff for a living will know how to build-stuff.",
"A foreman relays instructions from blueprints to workers. ",
"[Who needs plans, when you've got a guy walking around with one of these?](_URL_0_)",
"Construction is very specialized. Usually the person who does the layout is not the same person doing the physical work. On my project, for instance, there is a primary construction guy who basically makes X marks on the ground to denote where certain column type structures need to go (using the plans), and then an engineer checks and confirms those marks (using the plans), and then the workers go ahead and place the thing (holding no plans). \n\nIncreasingly these days, these drawings will be on an iPad. A set of design plans is actually hundreds of pages long (you need some pages just to show where the electrical stuff goes, some pages just for the plumbing, and so on), so it's possible you may pass a work site and see no one holding paper scrolls, like they used to do. "
]
}
|
[] |
[] |
[
[],
[],
[
"http://www.mitre10.co.nz/Image/item/xlg/179863xlg.jpg"
],
[]
] |
|
qiymv
|
advanced math
|
I have heard of p = np as sort of the default example of unexplained mathematics. Could someone tell me what the equation is about? Thanks.
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/qiymv/advanced_math/
|
{
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"P=NP is theoretical computer science, which is technically math but not usually considered as such.\n\nHot topics in pure math right now are:\n\n**WARNING THE FOLLOWING IS NOT ELI5 AT ALL**\n\n* [algebraic geometry](_URL_6_): the study of shapes [locally] defined by a system of polynomial equations. Classically, algebraic geometry relies on a [link](_URL_15_) between geometry and algebra, making it possible to use a *very specific* area of algebra to answer geometrical questions. On the other hand, the geometric perspective gives insight into algebraic questions. One of the major innovations of 20th-century mathematics (due to [Grothendieck](_URL_12_)) was the introduction of [schemes](_URL_16_). Rather than restricting ourselves to a *very specific* area of algebra, schemes make it possible to view all of [commutative] algebra from a geometric perspective. This technical flexibility also makes it easier to frame and answer questions of classical algebraic geometry.\n\n* [category theory](_URL_19_): at the beginning of the 20th century, there was a big crisis over the foundations of mathematics, and a lot of work went into describing what mathematical objects \"are\". An innovation of the 50s was that it doesn't matter what things *are*, what matters is *how they behave*; and furthermore, one can't study a mathematical object \"in a vacuum\", instead one must look at *relationships between the objects*. Category theory provides the foundation for this enlightened perspective; in some ways it is a \"theory of theories\", allowing one to study the relationships between the different areas of mathematics; the idea of looking at relationships is not just a philosophical principle, but can in fact be stated as a [mathematical theorem](_URL_0_). Since it encompasses so much, category theory is extremely abstract, often being referred to as \"general abstract nonsense\". Though originally intended as an insult, category theorists now consider this phrase a badge of pride.\nGrothendieck (see above) made extensive use of category theory in his view of algebraic geometry. His work has also driven the development of [higher category theory](_URL_14_), which takes the philosophy of category theory to its logical conclusion, looking not only at relationships between objects, but relationships between relationships, relationships between relationships between relationships, and so on.\n\n* [noncommutative geometry](_URL_8_): hard to explain, but relates to the idea of understanding algebraic objects from a geometric perspective.\n\n* [algebraic topology](_URL_7_): has its origins in [topology](_URL_3_) (related to geometry), but nowadays it's very much concerned with taking care of all the areas of algebra it spawned in the 1900s. The main idea is to study a complicated object by associating to it an algebraic object which is 1) simpler to analyze, but 2) retains enough information about the original object that we can deduce useful things; this is the notion of a [functor](_URL_20_). For example, an important property of a shape is the [number of holes](_URL_13_) it has; a more sophisticated look at the different \"kinds\" of holes, as well as how they interact, gives [homology](_URL_18_) functors. Or we can look at how one can move around on a shape; this gives [homotopy](_URL_9_) functors. Category theory came about because of the need to study relations between homotopy functors and homology functors. You may also have heard of [knot theory](_URL_4_), which falls under algebraic topology.\n\n* [homotopical algebra](_URL_1_): my personal area of interest; could be considered an area of algebraic topology. Attempts to apply the ideas of homotopy (see above) to other areas of mathematics. Heavily entrenched in category theory.\n\n* [string theory](_URL_17_): an area of physics that makes use of pretty much every area of mathematics there is, and is driving a lot of modern research. The above areas I mentioned are central for understanding the geometry of the universe, but it also has relations to weird things like [number theory](_URL_5_), which is generally considered useless outside of a few applications to cryptography.\n\nThis list is far from complete: algebra and geometry are my areas of interest, but there's also [analysis](_URL_10_), [number theory](_URL_5_), and all of [applied mathematics](_URL_11_). For a more complete view, you could skim the [Mathematics arXiv](_URL_2_) to see what mathematicians are researching. (you need to be a grad student to understand even 1% of what's on there, but it could be interesting to poke around the different topics)"
]
}
|
[] |
[] |
[
[
"http://en.wikipedia.org/wiki/Yoneda_lemma",
"http://en.wikipedia.org/wiki/Homotopical_algebra",
"http://arxiv.org/archive/math",
"http://en.wikipedia.org/wiki/Topology",
"http://en.wikipedia.org/wiki/Knot_theory",
"http://en.wikipedia.org/wiki/Number_theory",
"http://en.wikipedia.org/wiki/Algebraic_geometry",
"http://en.wikipedia.org/wiki/Algebraic_topology",
"http://en.wikipedia.org/wiki/Noncommutative_geometry",
"http://en.wikipedia.org/wiki/Homotopy",
"http://en.wikipedia.org/wiki/Mathematical_analysis",
"http://en.wikipedia.org/wiki/Applied_mathematics",
"http://en.wikipedia.org/wiki/Alexander_Grothendieck",
"http://en.wikipedia.org/wiki/Genus_%28mathematics%29",
"http://en.wikipedia.org/wiki/Higher_category_theory",
"http://en.wikipedia.org/wiki/Hilbert%27s_Nullstellensatz",
"http://en.wikipedia.org/wiki/Scheme_%28mathematics%29",
"http://en.wikipedia.org/wiki/String_theory",
"http://en.wikipedia.org/wiki/Homology_%28mathematics%29",
"http://en.wikipedia.org/wiki/Category_theory",
"http://en.wikipedia.org/wiki/Functor"
]
] |
|
9x3iwm
|
melting glass
|
So, my fysics teacher says that glass is a liquid and that it will evetually flow out if I place a glass ball on a table, and I belive that, but then I asked him if its possible to make it a solid and he didnt know so Im reaching out to you guy and asking, is it possible to make glass solid?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/9x3iwm/eli5_melting_glass/
|
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"text": [
"Your physics teacher is WRONG. People used to believe glass was a liquid but in fact that is a myth caused by medieval windows deforming over time.\nCheck out this article for more info: _URL_0_",
"It's not a liquid, but an amorphous solid. Think like clay. It's a solid, but it's soft, and when shaped right, it will change a little due to gravity. Same reasoning, but slower with glass.",
"That's a common misconception. Glass is an amorphous solid, in that it lacks a crystal structure (it's not repeating; it's random).\n\nYour physics teacher is a moron",
"Glass is not a liquid but rather an amorphous solid just like most metals. If you have a piece of glass fiber you can see how it easily bends just like a strand of steel. However it is still a solid. At some point we did think that glass were liquid. Firstly glass does not have a regular crystal structure which is one of the reasons it is transparent. If you look at regular rock which have similar chemical composition to glass it becomes transparent when you heat it up to a liquid as it looses its regular crystal structure. In addition to this we could measure the thickness of glass which have been mounted in windows for hundreds of years. In these windows the bottom were always thicker then the top. So it was reasonable to assume that glass were a liquid. However there are several issues. Firstly the state of matter does not depend on weather or not there is a regular crystal structure or not. And secondly the way they made windows before did not make flat glass and so the windows were intentionally mounted with the thicker side down. If glass were a liquid it should be possible to cool it down so that it eventually became a solid. At absolute zero temperature all matter is a solid. However glass does not change its crystal structure as you cool it down."
]
}
|
[] |
[] |
[
[
"https://www.scientificamerican.com/article/fact-fiction-glass-liquid/"
],
[],
[],
[]
] |
|
2qkbpy
|
does ac electricity work and why/how does the current shift direction?
|
Also. What on a smaller scale uses AC?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/2qkbpy/eli5_does_ac_electricity_work_and_whyhow_does_the/
|
{
"a_id": [
"cn6velb",
"cn6vn0y"
],
"score": [
3,
3
],
"text": [
"Imagine a circuit with a battery powering a lightbulb. The electrons flow from one end of the battery around the circuit to the lightbulb and back to the battery. Now if you flip the battery so that the electrons flow the other way the lightbulb isn't going to care and will still light up. Alternating current is basically just a circuit that switches between these situations very quickly. The electrons alternate their direction of flow. \nEdit: didn't really answer how this is done. They spin a magnet inside a coil of copper wires. When the positive pole faces one end of the bundel it pulls the electrons one direction. When the magnet faces the other direction it pulls the electrons the other way through the circuit.",
"It's because a rotating magnetic field is used to generate power in a coil. The rotation by nature causes oscillating polarity. Plot the position of a point on a rotating circle as a graph and you will understand why the voltage changes polarity. "
]
}
|
[] |
[] |
[
[],
[]
] |
|
1vur07
|
What's the biggest living form ?
|
And is there such a thing as a size limit for a living form ?
|
askscience
|
http://www.reddit.com/r/askscience/comments/1vur07/whats_the_biggest_living_form/
|
{
"a_id": [
"cew1aqg"
],
"score": [
5
],
"text": [
"It depends on where you draw the line for what a single \"organism\" is. \n\nI believe the largest organism on record that is generally accepted as a single unit is a [mushroom colony found in Oregon](_URL_0_) that spanned a couple thousand acres and weighed over 600 tons. \n\nThe Wikipedia page gives you a good idea of the scale you can expect in each kingdom, but at at any time, I'd say it's overwhelmingly likely that the largest living thing is going to be either a plant or fungus of some sort, since they aren't as limited by structural concerns as animals are. \n"
]
}
|
[] |
[] |
[
[
"http://en.wikipedia.org/wiki/Largest_organisms#Fungi"
]
] |
|
f79g4d
|
What civilisation existed before Sumer? I know a little bit about Jericho & Cathalhoyuk, but I’m not too sure about anything else & can’t find too much around the internet
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/f79g4d/what_civilisation_existed_before_sumer_i_know_a/
|
{
"a_id": [
"fib48nh"
],
"score": [
123
],
"text": [
"**Sumer is the first \"civilization.\"**\n\nArchaeologists have used many definitions of \"civilization\" over the years, but today most use it to mean urbanized, state-level societies.\n\nA \"civilization\" has *all* of the following: (1) cities, with large, complex social organizations, themselves in much larger territories than in earlier times; and (2) centralized economies based on tribute and taxation; and (3) advances toward formal record-keeping, as well as some form of written script or a close alternative; and (4) impressive public buildings and monumental architecture, such as palaces and temples; and (5) some form of all-embracing state religion and ideology in which the ruler played a leading role, often as a living god.\n\nBy this definition, the first civilizations were Sumer and Egypt. People were farming in northern Iraq by 8,000 B.C.E., and the city of Eridu had a mud brick temple by 4,700 B.C.E. As early as 3,500, a secular ruler governed the city of Uruk, and writing evolved around 3,400. True Sumerian civilization evolved around 3,100 B.C.E.\n\nLikewise, people farmed along the Nile River by 5,000 B.C.E., and Upper Egypt (in the south) consisted of several pre-dynastic kingdoms by 3,500 B.C.E. The first pharaoh of unified Egypt ruled in about 3,000 B.C.E.\n\n**TL;DR: there was no \"civilization\" before Sumer. Sumer became a civilization in approximately 3,100 B.C.E. Egypt evolved independently as a civilization around the same time.**\n\n**What about humans before Sumer?**\n\nModern humans (*homo sapiens sapiens*) evolved before 100,000 years ago. They lived as roving bands of hunter-gatherers until they learned to farm in approximately 10,000 B.C.E.\n\nThe inhabitants of the Abu Hureyra mound in Syria hunted gazelle to the exclusion of almost any other game. They also lived off about half a dozen staple grasses but knew of at least 200 others for eating, medical, and ritual purposes. To a considerable extent, they were managing and tending their environment well before they domesticated plants. Abu Hureyra began as a small village around 10,500 B.C.E. and flourished until 6,500 B.C.E.\n\nSimilarly, Jericho in the West Bank (Israel/Palestine) is indeed one of the most important antiquity sites that teaches us about the change to settled agriculture.\n\nUnderneath extensive Iron Age and Bronze Age occupation layers, Kenyon unearthed two much earlier farming settlements with substantial houses. The earliest of these, dating to earlier than 9,000 B.C.E., was a cluster of beehive-shaped huts. The closely packed dwellings nested inside a rock-cut ditch nearly 9 feet deep and a well-built stone wall complete with a tower.\n\nThe fortifications of this large village, which covered nearly 10 acres, are a mystery. They were either built for defense—Jericho lies astride a strategic route from the coast to the desert⎯or, perhaps, as flood control works.\n\nAfter farming developed in Southwest Asia, it spread to Europe by 7,000 B.C.E. We know less about farming in East Asia, but archaeologists believe wild rice collectors in the Yangtze Valley turned to deliberate cultivation between 7,200 and 5,500 B.C.E. Archaeologists believe Mesoamericans domesticated squash by 8,000 B.C.E. People may have domesticated maize in the Mexican lowlands by 5,000 B.C.E. The Andeans tamed quinoa and the potato earlier than 2,000 B.C.E.\n\n**Okay, but what about art, culture, religion, and burial practices -- the other elements of proto-civilization?**\n\nSometime between 40,000 and 30,000 years ago, Europeans first began making ornaments, such as beads, pendants, and perforated animal teeth to adorn their persons. At about the same time, the Cro-Magnons (modern European humans) started painting images of animals, signs, and anthropomorphic figures on cave walls.\n\nThe Cro-Magnons were brilliant artists in stone, antler, bone, clay, ivory, and probably wood. The Cro-Magnons are most famous for their rock art—paintings and engravings deep in the caves of southern France and Spain.\n\nHumans had developed ideas of kin ties and the supernatural by 18,000 years ago. During the summers, neighboring groups came together at specific locations where game or salmon were abundant for a few weeks a year. At these times, groups arranged marriages, performed initiation ceremonies, practiced highly intense rituals, and invoked the ancestors and forces of the spiritual world to ensure the continuity of life. Shamans told tales and wove spells.\n\n**TL;DR: I know you didn't ask about Cro-Magnons and the Neolithic Revolution (invention of farming), but these are crucially important for understanding human technology and culture before the first civilizations arose in Sumer and Egypt.**\n\n**Paleolithic and mesolithic humans (hunter-gatherers before humans invented farming) made beads, jewelry, decorated weapons, and magnificent rock art starting 40,000 years ago. They developed kin groups, marriage, story-telling, ceremonies, and shamanic proto-religions.**\n\n**The oldest archaeological evidence of farming dates to Abu Hureyra in Syria in 10,000 B.C.E. People farmed near Jericho in the West Bank around 9,000 B.C.E. Farming developed in Europe, East Asia, and the Americas after that.**\n\n**Human groups lived in tribes, settlements, and villages with this primitive art, social organization, and farming until Sumerian and Egyptian civilizations arose around 3,000 B.C.E.**\n\nSources:\n\nBrian Fagan, *People of the Earth*.\n\nBruce Smith, *The Emergence of Agriculture*.\n\nClive Gamble, *The Palaeolithic Societies of Europe*.\n\nKathleen Kenyon, *Digging up Jericho.* \n\nBrian Fagan and Kenneth Garrett, *Egypt of the Pharaohs*.\n\nChris Scarre and Brian Fagan, *Ancient Civilizations*.\n\nPaul Kwiwaczek, *Babylon: Mesopotamia and the Birth of Civilization*.\n\nSamuel Kramer, *The Sumerians*.\n\nNote to self: don't type about archaeology on my phone. Corrected multiple misspellings of the words \"arch(a)eology\" and \"pharaoh.\""
]
}
|
[] |
[] |
[
[]
] |
||
5p0mkb
|
the shape of mushroom clouds
|
Why does the explosion from a nuclear bomb look like a mushroom?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/5p0mkb/eli5_the_shape_of_mushroom_clouds/
|
{
"a_id": [
"dcnmau4"
],
"score": [
2
],
"text": [
"The initial explosion is so intense and hot it pushes and burns the air around it out, when the energy dissipates it essentially creates a negative pressure zone. The rush of air back to the center point is moving very fast, when it collides with the dusty air from the other circular directions it rises, hence the mushroom stalk. As it moves up it cools off and spreads out. \n\nEdit to explain: the air from the explosion is already intensely hot and wants to rise, it's the in rush of air, and bounce back from the ground that forms the column. "
]
}
|
[] |
[] |
[
[]
] |
|
h1pfw
|
Why is it that water tastes differently when it comes out of the faucet slowly vs. quickly?
|
Or does it?
I frequently find that my glass of water seems to taste better when I let the water come out of the tap slowly, compared to when I let all of the water pour out quickly.
Could it possibly be an oxygen issue?
|
askscience
|
http://www.reddit.com/r/askscience/comments/h1pfw/why_is_it_that_water_tastes_differently_when_it/
|
{
"a_id": [
"c1ry0ot"
],
"score": [
2
],
"text": [
"I am no expert. I think that might be because the water has air in it when it comes out faster. If you look at it while coming out faster, you can see how it's not a steady stream, but it has air throughout. The change in taste probably comes from the amount of sediment in the water (more air = more sediment).\n\nOn a side note, I hear that hot tap water has a different taste than cold tap water. Anyone know why?"
]
}
|
[] |
[] |
[
[]
] |
|
1tqsm4
|
why do iphones and louis vuitton bags' prices are standard all over the world yet medicine prices vary extremely worldwide?
|
Am just sayin.
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1tqsm4/eli5_why_do_iphones_and_louis_vuitton_bags_prices/
|
{
"a_id": [
"ceajjdk",
"ceajluz",
"ceakkbk"
],
"score": [
9,
2,
7
],
"text": [
"Because drugs are very heavily regulated relative to consumer products.",
"The prices are practically the same on big name brand items because the companies that make them set pricing that their items are not to be sold beneath. Working in retail and wholesale distribution I have had more than one experience with a company that doesn't want to hurt their 'brand image' by lowering the price beyond a certain point. Another reason is that it can indicate how much profit they are making off of the end user.",
"I work in a pharmacy as a cashier / assistant and I see people paying different prices for the same drug! It isn't even a geographic thing. It all depends on your insurance and how much they pay toward your treatment and what they expect you to pay (your co-pay). \n\nAlthough there are some cases like in India the government has outlawed pharmaceutical companies from getting patents so that some stuff is generic in order to be affordable to their citizens. \n\nPrescription drug markets differ all over the world (supply & demand) and I'd imagine so does insurance companies and co-pays."
]
}
|
[] |
[] |
[
[],
[],
[]
] |
|
49hnbk
|
what 'diminishing returns' means in a gym sense
|
I understand it in an economic sense but I don't understand how it applies to resistance training, and how increasing intensity can inevitably result in a plateau in results.
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/49hnbk/eli5_what_diminishing_returns_means_in_a_gym_sense/
|
{
"a_id": [
"d0rvm3v"
],
"score": [
2
],
"text": [
"There is a hard limit to the amount of muscle you can gain with every passing year. When you first start, you will get a fairly good amount but this will diminsh every year from then on if you keep lifting without a long break. After a while, the amount will be quite negligble. This all applies when your are a natural lifter and are not using any anabolic steriods. Steriods will keep your progress significant and this hard limit wont be a consideration to your body."
]
}
|
[] |
[] |
[
[]
] |
|
1m7o2i
|
How were one or more miscarriages viewed in the late middle ages?
|
I tried this almost a week ago and got no replies, so I'm trying again.
I've tried searching for answers myself, but anything I find is related to induced miscarriages and abortions. How did people view miscarriages? Were women who tended towards multiple miscarriages viewed negatively? Would people blame a miscarriage on something a woman did or how a family behaved? Would there be "remedies" for future attempts?
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/1m7o2i/how_were_one_or_more_miscarriages_viewed_in_the/
|
{
"a_id": [
"cc6rxwi",
"cc6zv0v",
"cc742hi"
],
"score": [
3,
2,
2
],
"text": [
"From my source (Cunningham's *Children and Childhood in Western Society Since 1500*) it is implied that there was grief for children. Not much is mentioned when it comes to miscarriages. But people did show a lot of concern when a child the first seven years of a human's life, *infantia*, died. Especially if the child died because of famine, other forms of malnourishment, or accidents (that happened to Martin Luther's and the English clergyman Ralph Josselin's respective children. Both men lived in the said time period).",
"Miscarriage, per se, was not negatively viewed, nor were women who miscarried necessarily stigmatized. Miscarriage was fairly common in the middle ages, given the limited amount of prenatal care available to expectant mothers, and it would not be unusual for a woman to miscarry one or more pregnancies during her life. The only time it would reflect negatively upon the woman is if it were somehow shown that she had deliberately induced a miscarriage in order to terminate the pregancy, usually through the ingestion of some kind of herbal concoction. This is, incidentally, why you haven't been able to find much outside of induced miscarriage/abortion in your searching: most of the time, the only real record we would have of a miscarriage would be if the woman were charged with terminating her pregnancy. Sure, there might be public rumor (*fama*) that insinuated that she had deliberately ended her pregnancy, and this *fama* could be used against her in court. But if the miscarriage were natural and it was widely understood to be an accident or the woman wasn't at fault, no, there wouldn't have been any social stigma. There was, equally, the possibility of legal repercussions against the husband if, by abuse for example, he were found to have caused his wife to miscarry. I know that in the Salic Law under the Merovingian Franks, severe fines were to be charged against a man who struck a woman and caused her to miscarry, and even higher fines if the woman died as a result of the miscarriage.\n\nIn terms of preventing future miscarriages, there's a substantial amount of literature out there re: medieval gynecology. The measures could range from various herbal drinks to charms written on parchment to be laid over the womb of the expectant mother (the latter gets into a bit of a grey area regarding the intersection of magic and science in the middle ages, but were generally accepted as a valid practice). \n\nA good place for further reading is Monica Green's *The Trotula: An English Translation of the Medieval Compendium of Women's Medicine.* *The Trotula* is a gynecological text believed to date to twelfth or thirteenth-century Salerno, and was a widely-read medical text that also summarized much of accepted gynecological practice during its day, including things like contraceptives and treatments for pregnant women. On the issue of miscarriage it says things like: \n\n > Note that when a women is in the beginning of her pregnancy, care ought to be taken that nothing is named in front of her which she is not able to have, because if she sets her mind on it and it is not given to her, this occasions miscarriage...\n > If her belly is distended from windiness, take three drams each of wild celery, mint, and cowbane, three drams each of mastic, cloves, watercress, and madder root, five drams of sugar, two drams each of castoreum, zedoary, and gladden. Let there be made a very fine powder, and let it be prepared with honey, and let three scriples of it be given her with wine. This medicine takes away windiness and [danger of] miscarriage if it is taken as it should be needed.\n\nMore answers might actually be found in those works on induced miscarriage and abortion, because, as I said, that's where you get the clearest discussion of miscarriage in medieval society. The most recent summative work I can recommend is Wolfgang Mueller's *The Criminalization of Abortion in the West: Its Origins in Medieval Law*, which just came out last year. ",
"Related question- how aware were Medieval women about their own gravidity? Even today, 50% of pregnancies end in miscarriage (and I'd imagine it would be much higher in the past) and most of those miscarriages happen in the first trimester, where a miscarriage can be mistaken for a simple period - the women might never know whether they were pregnant at all."
]
}
|
[] |
[] |
[
[],
[],
[]
] |
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