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8ju1bq
|
How does a compass work on my smartphone?
|
askscience
|
https://www.reddit.com/r/askscience/comments/8ju1bq/how_does_a_compass_work_on_my_smartphone/
|
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"With a device called a Hall Effect magnetometer, which is a solid state device that produces a voltage proportional to the strength of a magnetic field (such as the Earth's) along a particular axis.\n\nBy having two sensors at right angles, the phone can determine its heading/direction relative to the Earth's magnetic field.",
"People keep saying that traditional compasses are more accurate than hall effect ones, and are less prone to close distance interference such as electronics, but wouldn't a normal compass be prone to these obstructions? ",
"People have already explained how, so hopefully you don't mind me explaining why not to for precise measurements due to the phones limitations.\n\nThis is a common debate amongst Geologists. In the field we generally use Brunton Compasses (one of the geological transit models) for their incredible accuracy. \n\nLately many have been using their phones with compass apps because it's... \"Close enough\". \n\nThe issue is you can easily be off a few degrees if your compass or phone is not perfectly level. The Brunton solves this by using a planar level for measuring bearing. The phone however does not have a particularly accurate digital level, and the level they do have isn't necessarily on the compass apps.\n\nAnother point which is more of a measure of convenience is that you can manually adjust your compass to the magnetic declination of wherever you are at. Most phone apps don't have this feature so you'll have to add or subtract the value accordingly for each measurement. ",
"I'm also curious as to how the altimeter works on a smart phone. I've been in the middle of nowhere with no service on 13/14,000ft peaks, and it seems to be spot on with the altitude measurements. Would love to know the science behind that. ",
"Employee who works for the Magnetometer company that's in 80% of the world's smartphones here. The ECompass is highly dependent on both layout and the SW algorithm that is used. Layout needs to be done correctly, (away from hard and soft iron sources). For instance, you can't put it next to anything a magnet would stick to, and you can't stick it next to a high power trace. \n\nSo, with layout done correctly, it's up to the algorithm to calculate north. Accuracy can be accomplished via the, \"figure 8\", (or any random movement). That figure 8 thing goes back to a few meetings with customers years and years ago and became the standard explanation. Honestly, any random 3D movement calibrates the part. There have since been improvements in the algorithm that figure 8's aren't needed anymore. (But, this depends on who uses which part and which algorithm.) An error of < 5 degrees is typical with a correctly implemented design. But, remember that a lot of smartphone companies do not request help with this and implement it horribly, as it's usually though of too late. As for algorithms, many of the biggest smartphone and chip companies claim to have SW that implements an ECompass, but we've yet to see it comparable. I've seen one algorithm better than ours. Also, the algorithm needs to have dynamic calibration. The magnetic environment changes constantly as you move, thus compensation needs to change. (For instance walking into a huge steel building will completely change the magnetic fields vs. outside.) So, in the end, the biggest problems with an ECompass is usually just bad implementation.\n\nThe ECompass in smartphones rely on the accelerometer for tilt compensation. It can be done without it, but then the ECompass function would only work on flat surfaces. The accel lets you hold the phone in any position and still calculate north.\n\n(edited to add a bit about dynamic calibration)\n\n",
"The compass in a cellphone is a complicated device. The simple answer is that it is 2D Hall effect sensor that measures the magnetic field of the earth. That would not be an accurate compass at all.\n\nFirst, it is a 3D Hall effect sensor. This giver the instantaneous magnetic vector. This varies a lot with metal and electricity around you (in an urban jungle for example, this compass would be useless). However the errors cancel out as you move about over some minutes.\n\nSecondly, your phone has 3D gyros as well. This pretty much has the opposite properties. It is not affected by the surroundings, but drifts off a few degrees a minute, and become useless after a while without a new \"fix\".\n\nYou could try to use the gyros to keep track of the compass orientation, and then integrate away the instantaneous magnetic errors, and get a good compass. Then use this to fix the drift in the gyros again. So they fix each other weaknesses. This algorithm would depend a lot on the exact performance of all the sensors, as well on the environment to be optimal. It would also be very complex.\n\nThe beautiful solution is a kalman filter.\n\nThrow all the sensor data from X,Y and Z gyros X,Y and Z compass; Throw in X,Y and Z accelerometers and pressure altimeter for good measure, add GPS position and speed information, and out of the filter comes the best possible result of all of them cancelling each other errors and defects. The performance is amazing.\n\nTL;DR Use all the sensors on the phone, Kalman filtered, to make a good compass. \n\n",
"I am surprised no one mentioned that the compass in your phone is a MEMS device. Imagine a mechanical compass that is etched into silicon on a microscopic level. It really is some amazing stuff. \n\nCheckout this article for more info: _URL_0_",
"A hall effect sensor measures the voltage across a rectangle of silicon perpendicular to a constant current. Since the moving charge is affected by the magnetic field orthogonal to the current it causes a voltage. "
]
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e72x62
|
Gold Rush Miners of California
|
Most depictions of Miners in the late 19th century show them handing small pieces of gold to a man behind a cage for what appears to be a small amount of money. What kind of exchange rate was there at this time? Did they shorthand the Miners by a large amount in regards to how much the gold was actually worth? Was the exchange different for company Miners and people with their own claims??
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/e72x62/gold_rush_miners_of_california/
|
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"The exchange rate was about $16 per ounce and this was generally honored unless the gold was pale and apparently alloyed with a lesser metal (as was the case with gold from western Utah Territory, for example). California Gold Rush miners usually worked for themselves in small teams, so there wasn't a matter of \"company miners\" versus \"people with their own claims\": California miners typically worked their own claims.\n\nGold could be used for barter in the early communities, although very quickly various local mints started producing coinage to facilitate trade. \n\nI'm writing notes for the Journals of Alfred Doten, a '49er (who wrote from 1849 to 1903), and I wrote the following on the question of minting gold:\n\n > In the wake of the California Gold Rush, which began in 1848/1849, there was a chronic shortage of coinage to meet the demand caused by the thousands of new arrivals and by the increase in commerce they created. Trading in gold nuggets and dust required constant weighing of the precious metal and it depended on an often-incorrect assumption about the purity of the metal. Various private coins were issued to fill this gap and the United States Assay Office of Gold in San Francisco also began issuing stamped bullion with value indicated to facilitate trade. Congress was slow to create a U.S. Mint in San Francisco, but after some delay, that authorization was passed in 1853. At that point, the U.S. Assay Office closed, but there was a gap in operation as the U.S. Mint did not open until April 3, 1854, and even then, it was not ready to launch into production. John Glover Kellogg was a '49er who had secured employment with the U.S. Assay Office, and so he understood the process of coinage. To address the demand for reliable coinage in the thriving economy of the West, Kellogg with a series of partners began issuing twenty dollar \"double eagle\" gold coins beginning in early 1854, boasting that he was capable of a daily production of one thousand gold coins worth $20,000 per day. After the U.S. Mint formally opened, the need for coinage was far from being satisfied by the federal government, because copper and certain acids needed in the coinage process were in short supply. Kellogg consequently continued to produce his coins throughout 1854 and into 1855, ultimately minting about $6 million worth of the double eagle gold pieces. Doten is describing a devaluing of these privately issued coins in 1857; federally produced gold coins were becoming numerous enough that people were beginning to prefer official U.S. currency in place of private coins, resulting in a reduced value of the latter.\n\n > Source: Donald H. Kagin, Private Gold Coins and Patterns of the United States (New York: Arco Publishing, 1981).\n\n'49ers hoped to make their \"pile\" - which most regarded as something in the order of $10k so they could return home and go into business or buy a profitable farm. Becoming a millionaire was well outside the imagination of miners of the \"extensive\" gold resource. Later underground \"intensive\" deposits of gold and silver allowed for one to imagine becoming a millionaire, but that was extremely rare.\n\nA good day was when miners retrieved the equivalent of $3 or $4 worth of gold per day. Obviously, that was not to lead to gathering one's \"pile,\" but it did mean survival until one found a truly rich claim, which was all too elusive for most.\n\nFYI: [The Doten diaries](_URL_0_) were published in 1979 with about half the words printed. I am volunteering to assist in the transcription of the entire 79 books, and I am the editor of the notes. Also co-edited [The Gold Rush Letters of E. Allen Grosh and Hosea B. Grosh](_URL_1_) (2012) which informs this answer."
]
}
|
[] |
[] |
[
[
"https://clark.dotendiaries.org/",
"https://www.amazon.com/gp/product/1943859019/ref=dbs_a_def_rwt_hsch_vapi_taft_p2_i1"
]
] |
|
hx3d9
|
In science, is it possible for a measured/calculated quantity to have SI units equivalent to a fundamental concept, but not actually be that? [X-Post from /r/answers]
|
Note: I originally posted the question in /r/answers, and someone suggested to post in /r/askscience. [Original post](_URL_0_). Sorry for the mix-up, still getting the hang of reddit. Thanks!
====
In undergraduate physics I remembered reading in a book something along the lines of "Although [XYZ] has units of [abc], it is not actually [force,momentum,etc.]"
I thought that they were always equivalent, by definition. If a quantity has units of [kg][m]/[s]^2 then it is a Force, by definition. Likewise for momentum, energy, etc. Are there "counter-examples" to this assumption?
==
|
askscience
|
http://www.reddit.com/r/askscience/comments/hx3d9/in_science_is_it_possible_for_a/
|
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"The Hubble Constant, which measures the rate that the Universe is expanding, has units of km/s/Mpc -- which actually works out as units of inverse time. This doesn't really mean anything, as even when you invert it, the so-called \"Hubble Time' doesn't necessarily have to apply to anything real in the Universe.\n\n(It actually ends up as very close to the age of the Universe, but this is kind of a co-incidence due to a couple of rather complex factors). ",
"Well, first off there are things that don't *really* have the same units. For instance, both energy and torque have dimensions of force * distance, but one is a *vector* force * distance and one is a scalar.\n\nBut you can compute an arbitrary number of physical quantities with the units you want. For instance, if you want a number in m/s, I could give you the velocity of an object... or I could give you its length divided by some time interval, or the square root of potential energy over mass, or perhaps the number 6. They're in m/s, but they sure aren't velocities.",
"The stress tensor, a very important concept in fluid mechanics, has terms with units of pressure, but they're not actually pressures."
]
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[] |
[
"http://www.reddit.com/r/answers/comments/hwwy9/in_science_is_it_possible_for_a/"
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bory6j
|
how come you can power a radio exclusively via radio waves and we still have to charge our cell phones?
|
When I was a boy I built a crystal radio that fit into a tic tac box. This thing had no battery and ran a tiny little earpiece. Plans for these are available all over the net, I genuinely want to know why we aren’t using cell phone antennas to passively harness RF and rectify and recycle.
If it’s possible to listen to broadcast radio without batteries why can’t that (even if it’s microvolts) be harnessed? How does the front end of the cell receiver circuit dissipate the unwanted frequencies? ELI5 reddit, and thanks!
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/bory6j/eli5_how_come_you_can_power_a_radio_exclusively/
|
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"To do it at the power draw a cell phone requires your antenna would be impractically large. Remember that your phone is both a transmitter and a receiver.",
"Its a matter of scale.\n\nYour radio was able to function on just milliwatts of power, your phone has an ~11 Watt hour battery pack so if it lasts just 11 hours that means you're using about a watt of constant power. There just isn't enough random radio waves bouncing around to absorb to turn into a watt of power.\n\nYou'd need to capture 100-1000x as much power as your little radio was catching and that power just isn't available out there.",
"A crystal radio only take fractions of a Watt (measured in the thousandths) to move a *very tiny* speaker. A cell phone can easily draw 5-10W when you're using it.\n\nWe're talking about a ten thousandfold difference in the amount of power we need."
]
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34qmfs
|
why are "simple fix" patches for games always something like 30 megabytes?
|
Shouldn't they be very few, due to them not adding anything?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/34qmfs/eli5_why_are_simple_fix_patches_for_games_always/
|
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"I'm guessing that it's because they're edited bits of code and instead of editing it on your system, they just replace it. There might also need to be an installer downloaded or something like that",
"well they could be adding something or replacing a section of code or changing assets in some way. There's no universal answer it all depends on how the game was programmed, how it handles updates / patches and what exactly is being changed / fixed / added. 30 MB's is actually pretty small as far as today's games go. They contain so much code and so much high quality assets that small tweaks can add up to big patches very quickly.\n\nAnother important thing to note is that games on a code level have all of their parts interacting with each other in very specific ways so a small change to one part can actually require changes to a bunch of other parts and so forth so what may seem like a simple fix may not actually be so simple.",
"Fixing one line of code may require recompiling a large portion of object files. These object files in turn get linked together into a binary executable. The executable is what is shipped instead of object files or precompiled code.",
"A lot of the time, when code is changed, the size also changes. If the size is constant (such as changing a single variable, e.g. `gravity = 8.91` becoming `gravity = 9.81`, which simply overwrites the `8.91` with `9.81`) then the patch may be tiny, since only a few bytes are overwritten. But changing a function (what it is doing) will generally change the size because you will be adding or removing an instruction instead of just updating a value.\n\nUsually, functions are grouped together and compiled into a single binary containing the whole group, to save having < 10-byte files for every tiny function. But the code must know the position of each function in this binary so it knows where to look when it runs the function. If the function grows, then every function after that will have its position moved too.\n\nIf you're writing a neat piece of work with mistakes\n\n This is a very nice sentence that all sits on one line, but acentically contains a mistake or tow.\n ^ ^\n\nthen you could overwrite the `tow` with `tow`, and have a very small patch (`line 1, after position 95, overwrite with \"wo\"`), but you can't insert letters so easily - you can't do the old school trick of writing the fix\n\n ccident \n`but ac`\\^~~entic~~`ally contains a mistake or t`~~ow~~`wo`.\n\nabove your sentence, because programs don't normally contain margins. It also means that the letter at position 85 isn't a 't' anymore, but is now an 's', so any other references to the letters that have moved position have also need to be rewritten to prevent bugs. The same needs to happen when characters are removed - a bad reference may even point beyond the end of the line (which is very bad for security - it may be a secret word from the next page). So, to prevent these issues, instead of using a clever patching system that says `line 1, move everything to the right (easy), update all existing references manually (very hard), insert new text (easy)`, it's quicker and simpler in today's era of cheap memory to just say `line 1, overwrite everything with working new version (easy)`.",
"It's doable to make them much smaller than they are.\n\nDoable but surprisingly complicated and barely standardizable. There is little incentive in spending money on an effort to make the fixes smaller than 100 megabytes.\n\nInstead they send back the entirety of all files that are involved in the fix. It's fast, easy, it works and it is really not error-prone."
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41047z
|
how does the martian surface have pebbles?
|
[picture](_URL_0_)
[post of this picture](_URL_2_)
This is a picture of under Curiosity and you can see a bunch of small pebbles and rocks. However, with no water and [weak winds](_URL_1_), how do these small rocks break off from the bigger rocks?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/41047z/eli5_how_does_the_martian_surface_have_pebbles/
|
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"Weathering still takes place on Mars, it just does so much more slowly than it does on Earth. That said, water is believed to have been active fairly recently (in geological terms) in Gale Crater (Curiosity's site), and those pebbles may very well be water-deposited (some are believed to have been, though I don't know if these particular pebbles were)."
]
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[] |
[
"https://farm1.staticflickr.com/574/20662221345_f608a92f83_o.jpg",
"http://mars.nasa.gov/news/whatsnew/index.cfm?FuseAction=ShowNews&NewsID=1854",
"https://www.reddit.com/r/space/comments/40y190/under_curiosity/"
] |
[
[]
] |
|
5d4bir
|
Why was the Chernobyl shield/arch designed the way it is?
|
I've been looking at the structure (here: _URL_0_) and it is absolutely huge, with an enormous amount of empty space. That sort of surprised me - wouldn't a smaller structure sequestering a much small area around the immediate vicinity of the so-called "elephant foot" be sufficient?
Otherwise, I'd appreciate hearing about the design considerations behind this rather extraordinary structure.
|
askscience
|
https://www.reddit.com/r/askscience/comments/5d4bir/why_was_the_chernobyl_shieldarch_designed_the_way/
|
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"A) It would be not sufficient to enclose the \"elephant foot\", the rest of the building is also radioactive contaminated, as example one design requirement was: “They must minimize the amount of digging and cutting into the upper layers of the ground, as the upper soil is heavily contaminated with nuclear material from the disaster.”\n\nB) The goal of the structure is not only to enclose the radioactive parts, it is also intended to be used as a enclosed working are for a safe and remote controlled deconstruction and decontamination of the current shell. Therefore: “The NSC design is an arch-shaped steel structure with an internal height of 92.5 metres (303.5 ft), and a 12-metre (39.4 ft) distance between the centers of the upper and lower arch chords. The internal span of the arch is to be 245 metres (803.8 ft), and the external span is to be 270 metres (885.8 ft). **The dimensions of the arch were determined based upon the need to operate equipment inside the new shelter and decommission the existing shelter.**”\n\nAll citations from: _URL_0_ \n"
]
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[] |
[
"http://news.nationalpost.com/news/world/massive-shielded-arch-shaped-shelter-starts-crawl-toward-chornobyl-reactor"
] |
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"https://en.wikipedia.org/wiki/Chernobyl_New_Safe_Confinement"
]
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|
pf4vf
|
Is telekinesis even remotely possibly in any way shape, or form?
|
askscience
|
http://www.reddit.com/r/askscience/comments/pf4vf/is_telekinesis_even_remotely_possibly_in_any_way/
|
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"There is no established science, nor any experimental proof of such a phenomena.\n\nFurthermore, there is a [1 million dollar prize](_URL_0_) for anyone that can demonstrate such a thing under scientifically controlled conditions. Since that has been unrewarded - I think that pretty well sums it up.\n",
"Can you move objects with your mind? Sure, you do it all the time, in fact you are doing it right now, since your brain is moving your eyes along the screen while you are reading this. Similarly, your brain is responsible for moving your hands, which is responsible for all sorts of activities. There's no reason, from a scientific standpoint, why we can't replace a hand with some device that received the electric signals from the nerve endings and do some other action. Similarly, it could be possible to gather the outgoing signals in the brain directly and use them to perform some action.\n\nHowever, brain signals are not powerful enough to do very much on their own, they need amplification. In the human body the amplifiers are the muscles, and the energy source is ATP. So, you wouldn't be able to move an external object with your brain alone, but you could give it signals and provided it had a motor and a fuel source of its own, it could move where you tell it. It's almost telekinesis. And while it may not seem so exciting to the seekers of paranormal phenomenon, it's incredibly exciting to paraplegics and other people who have lost motor ability. ",
"it seems exceedingly unlikely considering the various laws of conservation of momentum and energy.",
"Since you are asking if it is 'even remotely possible', the answer is certainly yes. Especially depending on how you define 'telekinesis'. For example, look at the scientific explanation for quantum pseudo-telepathy. "
]
}
|
[] |
[] |
[
[
"http://www.randi.org/site/index.php/1m-challenge.html"
],
[],
[],
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||
2dfttv
|
if smoke is bad for you and contains carcinogens, how is it safe to eat meat that has been smoked for 6 hours?
|
I don't understand this. Yes, I get that the lungs and stomach are different, but either something contains carcinogens or it doesn't. If I take a slab of brisket and smother it in smoke for half a day, doesn't the meat absorb said carcinogens?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/2dfttv/eli5_if_smoke_is_bad_for_you_and_contains/
|
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"Tobacco isn't used to smoke food and cigarettes aren't made from wood. A lot of things we use and consume may contain carcinogens. But they are all used and or consumed in different ways. \n\nIt doesn't matter of its smoked. salty, spicy and sugary foods can be carcinogenic too.",
"Smoked meat is in fact pretty bad for you! Generally a piece of smoked meat has been salt rubbed and or salt cured to develop flavor and a crust. High sodium foods can lead to heart disease and type 2 diabetes. Furthermore, smoking meats can result in high levels of polycyclic aromatic hydrocarbons (the same process as when fat from meats drip onto a flame and flare up when you're grilling). These PAH's are in fact highly carcinogenic and can lead to pancreatic, colorectal and prostate cancers, amongst other forms of the disease. To make matters worse, when these PAH's chemically interact with nitrogen, you get a super carcinogen called NPAH (nitrated polycyclic aromatic hydrocarbons. These NPAH's are significantly more mutagenic than a base PAH. Bottom line. Smoked meat is bad for you. But it tastes oh so good!"
]
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|
[] |
[] |
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[],
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2aw69v
|
Dear Historians, how did the Japanese culture and country looked to the times of Julius Gaius Cesar? Have they been equal empires?
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/2aw69v/dear_historians_how_did_the_japanese_culture_and/
|
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"Julius Caesar likely never knew Japan existed. Julius Caesar likely didn't even know China existed. The Chinese themselves only knew of Rome sometime late in the Han Dynasty, where it was known as \"Great Qin.\" \n\nJapan was also only first mentioned in the late Han Dynasty as a \"Kingdom of Yamatai.\" For instance, the Romance of Three Kingdoms (which is historical fiction about the Three Kingdoms period (~300AD) written in the Ming Dynasty) recalls a conversation where they discuss a Yamatai which has a Queen, Hibiko. Hibiko, for that matter, is considered s semi-mythical ruler of Japan.\n\nJapan as we know it today was not fully organized until the subsequent Yamato period, and was not really well known by China until after Prince Shoutoku's embassies in the Nara period, a good 900 years after Caesar."
]
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|
[] |
[] |
[
[]
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||
4fhphm
|
why is it that the gas prices change at the pump, when the tanks underground were filled at a different price? why does the price of oil affect us at the pump so quickly?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/4fhphm/eli5_why_is_it_that_the_gas_prices_change_at_the/
|
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"Sellers of commodities, like gas station owners and refineries, price their product based not on what it costs to produce it, but on what it costs to replace it. ",
"the short answer is the information age. the profit on gasoline is tiny, on the order of pennies per gallon, so any retailer that wants to make money has to be constantly monitoring the price of his next shipment and factoring that into his sale price. the supplier that he buys from is also doing the same thing, and all the way back to the refinery. because the internet makes all this price research so easy and fast, we see the fluctuations at the pump every time some refiner or large trader gets twitchy.",
"If you bought some gold for $10, and then the price went up to $20, would you sell it for $10 because that's what you paid for it? No, you'd sell it for the current market price."
]
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1kcvr2
|
why do i have to wait an hour to install a game for my pc when i use a disk, but when i use a disk for my console, it takes minutes
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1kcvr2/eli5_why_do_i_have_to_wait_an_hour_to_install_a/
|
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],
"text": [
" Installing games to pc takes longer because all of the games data loads onto the hard drive and runs from that instead of the disc. whereas console games run off the discs and only install essential files to any built in hard drives. Some console games allow you the option to fully install a games content to your hard drive and it takes just as much time as a standard pc. The reasoning for this is because read time is faster from a hard drive than from a cd drive resulting in much smoother gameplay.\n\nEdit.\nAnother factor to consider in your 1 hour load time (which to me is unheard of in modern computing unless you have a really old machine.) is pc hardware being used. Not all disc drives are alike. Some read faster than others. cpu processing power available to process the data to your hard drive from the disc. "
]
}
|
[] |
[] |
[
[]
] |
||
6kwm87
|
what does an inverted cross symbolize? where did it come from?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/6kwm87/eli5_what_does_an_inverted_cross_symbolize_where/
|
{
"a_id": [
"djpciio",
"djpcqd4"
],
"score": [
2,
5
],
"text": [
"The inverted cross is the Cross of Saint Peter, and relates to Christian mythology due to the story (The Matyrdom of Peter) of Saint Peter being crucified upside down.\nLately it's been used as an anti-Christian symbol by directors and musicians to depict an anti-authoritarian or defiant message.",
"It comes from a legend about St. Peter's martyrdom. Allegedly, he was going to be crucified, but he felt that he didn't deserve to be killed in the same way Jesus was, so he asked to be hung upside-down instead. It's used now in the Catholic Church (along with keys) as a symbol of the papacy, because Peter was \"the rock upon which Jesus built his church,\" i.e. the first pope.\n\nIt's also sometimes used in anti-Christian circles as an inversion of the classic symbol (like how an upside-down American flag has the connotation of protesting America), usually by people who don't get that the inverted cross is *also* a Christian symbol."
]
}
|
[] |
[] |
[
[],
[]
] |
||
100ktu
|
Bras/chest support in Roman times?
|
Can anyone here link me to resources on what Roman women used as bras? I am also looking at both earlier and later if you happen to have any relevant resources?
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/100ktu/braschest_support_in_roman_times/
|
{
"a_id": [
"c69cgek",
"c69d8fw",
"c69eefl"
],
"score": [
32,
18,
6
],
"text": [
"Not bra, but we have really well preserved mosaics of roman women in bikini swimwear: [Villa del Casale](_URL_0_).",
"I've seen some references to a garment called a strophium or mamillare, which is described as a band that's wrapped around the bust.",
"Not sure if this will be helpful to you, but your question reminded me of [this article](_URL_0_) I read not too long ago."
]
}
|
[] |
[] |
[
[
"http://en.wikipedia.org/wiki/Villa_Romana_del_Casale"
],
[],
[
"http://www.guardian.co.uk/commentisfree/2012/jul/20/medieval-bras-history-women-support"
]
] |
|
14vszw
|
what being in love feels/is like
|
I did not find this asked before when I searched, if there is one, please link me and I'll mark this as answered.
If not, how do I know if I am in love with another person? What's the difference between really caring about someone and being in love? If I know I love someone (with romantic parts to the relationship), what is the difference between loving that person and being IN love?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/14vszw/eli5_what_being_in_love_feelsis_like/
|
{
"a_id": [
"c7gvsch",
"c7h0psr"
],
"score": [
9,
2
],
"text": [
"Love is what is left when the honeymoon phase is gone. It is like having a puppy. The first day you bring him home it is the greatest thing in the world. You are so excited that they can do no wrong. Then 6 months later that same puppy has just chewed your remote control and shit on your bed. If you love them you will work through it. You will make compromises and teach them what you need while also meeting their needs. If you were just in lust with them you will send them to the pound. \n\nLove is growing with someone and making sure that you grow next to them not away from them. ",
"For me it is that person being your best friend. You can talk about anything and even if you disagree, it's an intelligent, enjoyable conversation. You care so deeply and passionately that you would risk your life for them either in the blink of an eye or over a long well-contemplated time line. You want to protect them, and you are inherently trustful of them. You don't feel the need to prove your love to anyone, wether on Facebook, with PDAs (public display of affection), or otherwise. However some days that person makes you want to scream how much they complete you from the top of Everest and then proceed to smother them in love and kisses and adoration. All your friends get along, at least the important ones, and even if they don't, they see how happy you are and try to get along. Life with someone you love just flows... Problems and difficult decisions and circumstances just smooth over. When you work together you can conquer anything. Even if your in a terrible mood you try to not act like a pouting 5 year old because you know it's not productive and you can talk through anything. It simply feels natural. Most importantly you treat each other right because you each deserve the best and you can always be yourself. \n"
]
}
|
[] |
[] |
[
[],
[]
] |
|
4fiy6q
|
What properties of blood can sharks "smell"? Notothenioids have clear blood because it contains no hemoglobin, a feature no other vertebrate shares. If notothenioid blood was put in a shark tank would sharks recognize it as blood?
|
askscience
|
https://www.reddit.com/r/askscience/comments/4fiy6q/what_properties_of_blood_can_sharks_smell/
|
{
"a_id": [
"d29x6s2"
],
"score": [
3
],
"text": [
"Following the references from the smell section of the [Wikipedia page for sharks](_URL_1_), one is broken, but the other yields this:\n\n > Experiments on isolated olfactory lamellae of certain skates (family Rajidae) have revealed astonishingly low [thresholds] to chemical stimuli — responding to concentrations as low as 10^-14 moles per litre of water for the amino acid serine (or about 1 molecule of serine in 10^15 molecules of water). In terms of relative volume, this is comparable to detecting a golf ball in Loch Ness.\n\n > [_URL_0_](_URL_0_)\n\nninja edit: here's the other reference: [_URL_2_](_URL_2_) - nothing about blood\n"
]
}
|
[] |
[] |
[
[
"http://elasmo-research.org/education/white_shark/smell.htm",
"https://en.wikipedia.org/wiki/Shark#Smell",
"http://sci-hub.io/10.1016/j.cub.2010.04.053"
]
] |
||
69gw2v
|
I'm a Roman Emperor ruling in Rome. The Persians attack in the East. How does the news get to me, and how long does it take?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/69gw2v/im_a_roman_emperor_ruling_in_rome_the_persians/
|
{
"a_id": [
"dh72mva",
"dh73dab"
],
"score": [
2,
22
],
"text": [
"As an aside were there any Persian empires at the time of imperial Rome to fight? My understanding was that the successor states were Hellenic like the Ptolemys in Egypt and not very Persian.",
"The news of the attack would reach you via a government courier (think pony express) who travelled along the Cursus Publicus (the public way). These paved highways connected the empire to its distant provincial territories and trading partners. It was created by the Emperor Augustus to facilitate the flow of taxes, messages, and services. Take a look at the Tabula Peutingeriana to get an idea of what the extant routes were in the year 400AD. \n\nHere is a description by 7th century Procopius describing an earlier time: \n\n\"The earlier Emperors, in order to obtain information as quickly as possible regarding the movements of the enemy in any quarter, sedition, unforeseen accidents in individual cities, and the actions of the governors or other persons in all parts of the Empire, and also in order that the annual tributes might be sent up without danger or delay, had established a rapid service of public couriers throughout their dominion according to the following system. As a day’s journey for an active man they fixed eight ‘stages,’ or sometimes fewer, but as a general rule not less than five. In every stage there were forty horses and a number of grooms in proportion. The couriers appointed for the work, by making use of relays of excellent horses, when engaged in the duties I have mentioned, often covered in a singly day, by this means, as great a distance as they would otherwise have covered in ten.\"\n\nUsing this description and mapping out the way stations along each route, the scholar A.M. Ramsey was able to determine an average distance of 50 miles per day for a fast traveling system of royal couriers. Keep in mind though that bad news would have travelled faster than good news. \n\nThe Iranian borderlands are roughly 2000 miles from Rome, so 50-60 miles per day it would take just over a month to reach Rome. \n\n\n"
]
}
|
[] |
[] |
[
[],
[]
] |
||
3g5x3u
|
Does the behavior of plasma share any similarities with that of fluids?
|
The containment of Plasma in Nuclear fusion reactors for example requires an understanding of its behavior in response to magnetic fields and such.
Does plasma behave in a way analogous to fluids under certain conditions and if so, can the laws governing fluid dynamics be somehow transplanted with necessary modifications and be applied to plasma?
|
askscience
|
http://www.reddit.com/r/askscience/comments/3g5x3u/does_the_behavior_of_plasma_share_any/
|
{
"a_id": [
"ctv8h7c"
],
"score": [
4
],
"text": [
"Yes, the equations of plasma physics can be approximated by a fluid model in certain regimes. For instance, in an intense (non-neutral) cyclotron beam, we typically assume that the plasma is \"highly magnetized\", which means that the externally imposed magnetic field is much stronger than the self-electric field produced by the plasma itself. If we also assume that the particles in the beam move on small orbits within the beam, the equations of plasma physics reduce to exact fluid equations. (Note, however, that the equations are only *formally* fluid-like. The variables involved may not really have much to do with flow.)\n\nWhy do fluids even obey the fluid equations? For one, any small region of fluid is assumed to contain enough particles so that the fluid can be approximated by a continuum. (A single drop of water contains about 10^(21) molecules.) This is the fundamental scale associated to a fluid, sometimes called the interparticle distance. (For water, this distance is about 10^(-10) meters.) It is always assumed to be very small compared to any other length scale of the problem.\n\nSo what about plasmas? The interparticle distance is not the only associated fundamental length scale. One such length scale is the [Debye length](_URL_0_), and this is the length scale that is more important than the interparticle distance. Indeed, we typically define a collection of charged particles to be an (ideal) plasma only if the Debye length is small compared to the length scale of the plasma motion. (We also require that the number of particles in a Debye volume be large, and that the so-called plasma frequency be much larger than the collision frequency.) The Debye length is emphatically *not* the interparticle distance. So, for instance, the interparticle distance of the solar wind is about 10^(-2) meters (a full 8 orders larger than that for water), and the Debye length is about 10 meters (a full 3 orders larger than the interparticle distance). Nevertheless, because the length scale of bulk of the solar wind is on the order of the size of the solar system (and because the other plasma criteria hold), the solar wind is, indeed, an ideal plasma. This seems very odd if you think in terms of fluids since there are regions we can see with our naked eye that may not contain a single electron!\n\nNot all plasma configurations can be described by fluid equations. Even if the plasma is an ideal plasma, the length and time scales may not all be in the regime where a fluid model is appropriate. A full kinetic theory of the plasma may be required. So an author on plasma physics will always be sure to identify the fundamental scales of the problem and the exact model which is allowed by those scales."
]
}
|
[] |
[] |
[
[
"https://en.wikipedia.org/wiki/Debye_length"
]
] |
|
1nrk0y
|
robitussin and other over the counter cold medicine, how does it work?
|
Is it a mixture of chemicals that serve to alleviate symptoms? Does it help the immune system fight in some way?
Does it actually help your recovery time, or does ot just make you feel more comfortable while your immune system takes exactly as long as it would have anyway to defeat an ailment?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1nrk0y/robitussin_and_other_over_the_counter_cold/
|
{
"a_id": [
"cclceui"
],
"score": [
2
],
"text": [
" > Is it a mixture of chemicals that serve to alleviate symptoms?\n\nYep.\n\n > Does it help the immune system fight in some way?\n\nNope.\n\n > Does it actually help your recovery time, or does ot just make you feel more comfortable while your immune system takes exactly as long as it would have anyway to defeat an ailment?\n\nIt's just for comfort. Suppressing coughs and clearing mucous mainly."
]
}
|
[] |
[] |
[
[]
] |
|
1zravl
|
Why did ancient chinese coins had a hole in their center?
|
Such as this: _URL_0_
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/1zravl/why_did_ancient_chinese_coins_had_a_hole_in_their/
|
{
"a_id": [
"cfw7wcu",
"cfw7ygz"
],
"score": [
5,
6
],
"text": [
"So that they could be strung together, in order to make them easier to carry around and so that you could make large purchases more easily (you could have a bundle of 100 coins, for example).\n\n[Here's an example](_URL_0_) from the British Museum.",
"In Imperial China, copper coins were often the smallest unit of currency. Since it was very hard to carry and keep many of these coins in one place, the hole was to string the coins together in one length on some fiber. From there, certain amounts of stringed coins denoted higher levels of currencies (say, maybe 1000 copper coins). After some of the later tax reforms, taxes were to be paid in silver to the imperial government, but silver was not in circulation in rural and western parts of the empire as much as it was in cities and the eastern parts. So, say if you were a farmer who needed to go about paying their tax, you would string together enough copper coins to trade for silver to pay your tax. This was a big issue in the Ming empire, as the copper-silver exchange rate was severely skewed towards silver and thus, it was more expensive for those who had to trade for silver to pay their taxes.\n\nOn a nit-picky note about your question, I'd correct you and say that these coins weren't all that \"ancient\". They were used for the majority of China's imperial history, in much the same form. The currency of antiquity, \"pre-unified\" China, was cowry shells, leading to the word for the shells to be associated with the ancient word for currency as well.\n\n\nCambridge's *History of China* is a good general resource for this sort of thing if you want to dig a little bit deeper. "
]
}
|
[] |
[
"https://www.google.com.mx/search?q=chinese+coins&es_sm=93&source=lnms&tbm=isch&sa=X&ei=UvYYU_msG4Pj2AX8zoHoCQ&ved=0CAkQ_AUoAQ&biw=1920&bih=988#q=ancient+chinese+coins&tbm=isch"
] |
[
[
"http://www.britishmuseum.org/explore/highlights/highlight_objects/cm/s/string_of_800_cash.aspx"
],
[]
] |
|
3fap3m
|
what's the reasoning behind the idea that money is free speech and (even small) contributions are not bribes?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/3fap3m/eli5_whats_the_reasoning_behind_the_idea_that/
|
{
"a_id": [
"ctmu5xy"
],
"score": [
9
],
"text": [
"It is because money is often used to promote speech - getting it to as many ears as possible.\n\nIf I were to shout on a street corner, this is easily considered free speech.\n\nIf I were to buy a printing press and print up fliers for an issue, this is easily considered free speech (or a free press, to get technical).\n\nIf I give money to someone who already has a printing press to print up fliers for an issue, this is easily considered free speech.\n\nIf I give money to an organization that is already printing up fliers for an issue, its easily considered free speech.\n\nIf I give money to an organization that supports a candidate that supports a particular issue, and that organization uses the money to help get the candidate elected so they can legislate the issue, its not a far leap to see how that would be free speech as well."
]
}
|
[] |
[] |
[
[]
] |
||
1z03pk
|
why don't we just bomb north korea's leaders with drones?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1z03pk/eli5_why_dont_we_just_bomb_north_koreas_leaders/
|
{
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"text": [
"Because China would get mad.",
"Logistically, even with drones, how would we do this?\n\nNK has had more than enough time to build its military infrastructure in such a way to handle more than the largest bomb a drone could drop. \n\nFurthermore, guys like Kim and his ilk don't hold all of the military power - there are tons of other guys in the wings who are just as capable of coordinating the NK military.\n\nThere are bunkers that no one knows about built in places that you can't see, built to take a pounding and still send launch codes to missile silos hidden all over the place.\n\nShort of turning the entire landmass into glass in an instant, the methodology of taking out the 'leaders' wouldn't do much. And they absolutely would retaliate - any external attack would likely trigger NK into firing onto at minimum South Korea.",
"I'm sure there are many nuanced explanations but the way I understand it, there is too much risk to the stability in the region. There are several really bad scenarios that could unfold - someone with some authority ordering a bum rush south, someone with a finger on a nuke deciding to end it all etc. Also - the idea of 'you break it, you own it' - no country really wants to own NK. ",
"I feel like that would be a bad idea because the US would be the ones breaking the treaty that ended the fighting of the current war in Korea.",
"Because your post isn't asking a simplified conceptual explanation, but rather for an answer, its been removed. \n\nYou should try /r/answers, /r/askreddit or even one of the more specialized answers subreddits like /r/askhistorians, /r/askscience or others too numerous and varied to mention. \n\nRest assured this doesn't make your question *bad*, it just makes it more appropriate for another subreddit. Good luck! "
]
}
|
[] |
[] |
[
[],
[],
[],
[],
[]
] |
||
3deeai
|
if vanilla extract is a brownish color, why is vanilla ice cream white?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/3deeai/eli5_if_vanilla_extract_is_a_brownish_color_why/
|
{
"a_id": [
"ct4beg4",
"ct4bgoh"
],
"score": [
4,
2
],
"text": [
"You need very little vanilla to achieve enough taste. Also more often than not its artificially colored. For instance when making chocolate chip cookies or edible cookie dough you'll find the same thing. Usually the recipe, which is crafted to serve at least several people only calls for 2-3 tsp of vanilla extract. If you ever want to test out the strength just put some on the tip of your finger and taste it. It's pretty damn strong! Haha",
"Vanilla ice cream is mostly sugar, ice, and milk or cream. Adding a teaspoon or 2 of vanilla extract barely changes the color. Also they do make clear vanilla extract for those who need pure colored food items"
]
}
|
[] |
[] |
[
[],
[]
] |
||
3c9pvo
|
why is the concept of social darwinism / eugenics so morally reprehensible?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/3c9pvo/eli5_why_is_the_concept_of_social_darwinism/
|
{
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"text": [
"One thing I can tell you is that social Darwinism is used as an argument, sometimes, to justify the poor being poor and the rich, rich, etc. \n\nWhich is ridiculous. And for that, it's frowned upon. But that's all I know.\n\nEdit: Reason number 2 for social Darwinism being bad: social Darwinism = weaker people \"naturally\" GTFO. The problem is, for that to work, you'd have to consider that nature's way is fair. Which would be very controversial (ex.: is Cancer \"fair\"? What would fair mean?)\n\n",
"In the case of social Darwinism, it devalues our basic humanity by saying that we should ignore and avoid any moral feeling for other people and let \"nature\" have its own way.\n\nEugenics arrives at more or less the same place, but by denying the basic humanity of individuals in making their own choices in favor of putting one person/group's definition of what is \"human\" over everyone.\n\nIn the end, they both deny the dignity and worth of the human individual.",
"Because it violates a persons natural rights. I understand why one would be inclined to see eugenics as noteworthy but unfortunately you can't just go around steralizing undesirable blood lines without being a tyrant. Basically white supremacist groups are eugenics groups, at least the ones that promote racial purity.",
"The core problem with Social Darwinism is that it completely ignores and denies the many external factors that influence a person's success in society -education access, social support, discrimination, parent's wealth, etc. It then allows the wealthy upper classes to justify their privileges and exploitation of the 'lesser' working poor. ",
"It's funny that a few questions down someone is asking:\n\n > ELI5: Why hasn't 'natural selection' weeded out all the animals that think it's safe to cross the road?\n\nThe basic answer being, evolution isn't fast enough and precise enough to achieve something like that yet. It might not ever in some species, if the advantage of successfully crossing the road isn't big enough relative to other factors.\n\nSo one half of the reason is pragmatic: eugenicists *vastly* underestimate how hard it would be to deliberately breed humans, and how much current humans have evolved in ways we can understand as \"breeds\". Time and again they just plain get it wrong, and use it as a rorschach to project their own prejudices onto, both racist and classist prejudices especially.\n\nThe other half of the answer is in principle: they violate what people understand to be their fundamental human rights. Some people might say \"so what\" but in your question you asked about it being considered \"morally reprehensible\", and for many people violating human rights is the very definition of immoral.\n\nThere are things that have more support from people (though not everyone) that could be considered eugenics, like genetic counseling for parents with a high risk of passing on genetic diseases to their children."
]
}
|
[] |
[] |
[
[],
[],
[],
[],
[]
] |
||
x5ktl
|
How popular was the concept of democracy in colonial America?
|
It was called a grand experiment and it sounds like many were skeptical that a democracycould even exist.
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/x5ktl/how_popular_was_the_concept_of_democracy_in/
|
{
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"text": [
"One thing you need to understand is that the term democracy has different meanings today then in 1787 America. Today we use the terms Republic and Democracy interchangeably, however in 1787 democracy would have meant direct-democracy( such as ancient Athens) the notion of this democracy was extremely unpopular among the founders. This can be seen from the fact that in the Early republic I have seen estimated that only 1/8 of white males could even vote.\n\nIf you are asking was their support for the notion of a King? Then yes, although extremely limited some founders did believe the United States should have a monarch although it probably would have been a limited monarchy, one delegate at the Constitutional convention went so far as to send a letter to Fredrick the Great's Brother ( if memory serves) and offer him the Crown of America. ",
"Colonial Americans were generally satisfied to be part of the British Empire. They believed that Britain had the greatest government on earth. It was great because it incorporated the three forms of government known to history. Those three forms were monarchy (rule by one), aristocracy (rule by the few), and democracy (rule by many). According to political theory, each of these forms of government, if left unchecked, will (accordingly) devolve into tyranny, oligarchy, or anarchy. What made the British system of government perfect was that it balanced monarchy (the King) against aristocracy (House of Lords) and democracy (House of Commons). \n\nThis suspicion of \"unmixed\" government was carried on into the formation of the American government. We have rule by one (the President) checked by the rule of the few (the Senate) and the rule of many (the House of Reps.). None of the founding fathers were interested in creating a \"democracy.\" That would just lead to chaos and national entropy. They created a balanced, federal republic.\n\nThe problem for the Founders is that ordinary folks just wouldn't stay quiet, and from the beginning there were calls for greater popular participation, through the Democratic-Republican Societies, from women, from freed blacks, and other pressure groups. Especially with the influence of the French Revolution of 1792, the word \"democracy\" came to sound, if not respectable, than worth considering. By the 1820s and 30s, it was more common to hear Americans claim that they lived in a \"democracy,\" and that a democratic government was a positive thing. Ideologues like George Bancroft and Amos Kendall pushed it forward.\n\nSo this was a long-term process.",
"It really depended on who you asked. Remember that the American Revolution was much more a political upheaval than a total remaking of society. As such, most of the \"Founding Fathers\" were men who were already rich and powerful before the Revolution broke out. Almost entirely, the upper gentry and aristocratic set to which they belonged feared a popular upheaval as much as they did Parliamentary infringements on their rights.\n\nBefore the Revolution, there were major populist (if not pro-democracy) uprisings in the two of the more \"aristocratic\" colonies, [Virginia](_URL_2_) [New York](_URL_1_), and in [North Carolina](_URL_0_). These rebellions generally caused major panic in the assemblies of the disturbed colonies, and were put down as quickly and as hard as circumstances allowed.\n\nDuring the Revolution, political rights expanded greatly, even including women in the state of New Jersey. Afterwards, though, the aristocrat set felt that this excess of democracy was a threat to the stability of the new nation, and rolled back democratic rights when they drafted the Constitution. \n\nFor a really good look at the question of democracy in and around the Revolution, check out Gordon S. Wood's *The Radicalism of the American Revolution.*",
"Throwing this out there for an actual historian to comment on: I don't think it makes sense to ask about colonial Americans as a whole. In New England, democratic town government was very popular, in the slave colonies in the deep south, not so much. "
]
}
|
[] |
[] |
[
[],
[],
[
"http://en.wikipedia.org/wiki/Regulators_of_North_Carolina",
"http://en.wikipedia.org/wiki/Leisler%27s_Rebellion",
"http://en.wikipedia.org/wiki/Bacon%27s_Rebellion"
],
[]
] |
|
13kr8g
|
Some smartphones, like the ones which use the Android OS have very short battery lives. What is stopping the companies from using larger batteries?
|
I am unsure if it has anything to do with production cost or design. Considering smartphones with Android OS, Motorola RAZR MAXX comes with a 3300 mAh battery, while being as thin as than 9 millimeters ( needless to point out that it has a significantly longer battery life), which is why I doubt phones need to be thicker to support more capable batteries. So I'm thinking a larger battery brings along a set of technical problems to address, if not anything else. But that's all speculation on my part, which I'm looking to clarify.
|
askscience
|
http://www.reddit.com/r/askscience/comments/13kr8g/some_smartphones_like_the_ones_which_use_the/
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"The ipad has a huge battery. If you put the same screen on it that a smartphone has, you would have a device that has an incredibly long battery life. The limiting factor is size.",
"The limiting factor is size/weight. My Samsung Galaxy S3 has a 2100 mAh battery. For $20 you can buy a 4500 mAh battery to replace it, but it comes with a new back cover because the extended life battery is much thicker.",
"Most smartphone companies are more concerned about making their phone even a fraction of millimeter thinner, so they sacrifice battery life for thinness. A great example of a company breaking this mould is Motorola with their Droid RAZR Maxx. They fit a 3300 mAh battery on it, so it isn't difficult, it's just a matter of what a phone manufacturers' priorities are when they make the phone."
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3up4ax
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why is everything so cold? why is absolute zero only -459.67f (-273.15c) but things can be trillions of degrees? in relation wouldn't it mean that life and everything we know as good for us, is ridiculously ridiculously cold?
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Why is this? I looked up absolute hot as hell and its 1.416785(71)×10(to the 32 power). I cant even take this number seriously, its so hot. But then absolute zero, isn't really that much colder, than an earth winter. I guess my question is, why does life as we know it only exist in such extreme cold? And why is it so easy to get things very hot, let's say in the hadron collider. But we still cant reach the relatively close temp of absolute zero?
Edit: Wow. Okay. Didnt really expect this much interest. Thanks for all the replies! My first semi front page achievement! Ive been cheesing all day. Basically vibrators. Faster the vibrator, the hotter it gets. No vibrators no heat.
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explainlikeimfive
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https://www.reddit.com/r/explainlikeimfive/comments/3up4ax/eli5_why_is_everything_so_cold_why_is_absolute/
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"The more atoms vibrate the hotter the temperature. The slower they vibrate the lower the temperature. They can vibrate as fast as they want but once they stop vibrating the temperature doesn't go any lower.\n\nIn other words, the lowest temperature means they are standing still. But they can always vibrate even faster no matter how fast they are vibrating right now.",
"Temperature is the average movement of atoms on a microscopic scale. \n\nAs such, there is a lower bound, when movement stops completely. There is no higher bound, as you can always move faster, though you begin seeing weird things once you reach a few billion kelvin, due to lightspeed and that.\n\nAnd while life occurs at very low temperatures, that is with good reason. All this movement tears molecules apart, making it impossible for things to properly exist at higher temperatures. Above 3600 Kelvin, everything is molten, for example.",
"The problem is sort of that the temperature scale has an absolute bottom but is close to being open ended at the top. (There might or might not be a theoretical 'absolute hot', but it would be far past any sort of context where talking about temperature makes sense. For practical purposes the scale might as well be open ended.)\n\nIn such a scale any sort of value always appears to be close to the bottom because there is always more room above than below.\n\nThe scale alone says nothing about what temperatures should be expected. The average temperature of the universe after all is only a few degrees above absolute zero. But that includes all sort of matter. One may look at the average or median surface temperature of planets and moons and come to completely different conclusions.\n\nLife on earth is based on chemical reactions in general and certain chemical reactions in particular. You don't get much chemistry when you heat things up too much. When you heat things up the energies all around you are greater than energies holding molecules together and letting them react with one another.\n\nChemistry starts happening close to absolute zero, but it stops happening if things get to hot.\n\nOur sort of chemistry happens at the sort of temperature we have on earth right now. The sort where liquid water exists.\n\nLife based on other chemical reactions that happen at much colder or slightly hotter temperatures are theoretical possible. Even life that is not based on chemistry at all and able to exists at completely different temperature ranges is perhaps possible, but we have never really seen any life other than that related to our own and have no idea what might or might not be out there.\n\nPerhaps we are alone. Perhaps life across the universe is usually found around the same temperature range that we are comfortable with. Perhaps we are an extreme outlier and most life exists at much higher or lower temperatures.\n\nWe can only guess.\n\nIf we look at our own solar system we have two planets mercury and Venus that are hotter than ours and the rest of the moons and planets that at least on their surface are colder than Earth. Based on that alone one might think that we are unusually warm.\n\nThe truth is we have no idea what should be considered normal, based on our extremely limited experience.",
"To answer part of your question, yes, the universe as we observe it is very cold.\n\nThe key word is observe.\n\nFor us to observe, we must be able to observe.\n\nTo be able to observe we have to exist.\n\nFor humans to exist, atoms must be in a stable state.\n\nFor atoms to be in a stable state, the temperature must be in a similar to what we observe.\n\nAt one point the universe was very hot, almost infinitely hot. Over 13 billion years, the universe has cooled significantly.",
"You can theoretically put as much energy into something, but is limited in what you can take out.",
"I always understood that we live on the extreme cold side of existance, mainly because it's the most stable.",
"Imagine you have a rocket with infinite performance and fuel. \n\nWhen you get in you are stopped. It's not possible to go slower. However once you start moving there is theoretically no limit to how fast you can move. ",
"This is because at higher temps chemistry is not possible. Once the heat/energies reach a certain level all the electrons are stripped away. We can't reach absolute zero because of thermal conduction. There is no such thing as a perfect thermal insulator so there is always some heat getting in and the lower the temp the harder it is to get it out.",
"Things can go very very fast, like a jet plane, but most 5 year old I know rarely move faster then a couple miles per hour. Even though toddlers rarely leave the very slow speeds it's almost impossible get get a live toddler to be absolutely still because the slightest distraction in the form of other movement will cause them to move in reaction. \n\nAtoms are like toddlers and temperature is like movement, it's hard to get all of it out of the system so things are absolutely still because where we live (and are doing the experiment also has energy). ",
"You could say life only exists in extreme cold because it's evolved to adapt to the extreme cold that's on our planet and it's the only life we know. \n\nBut on the other hand, the temperature life exists as we know of is an ideal temperature for carbon based lifeforms. Think about how carbon based lifeform works. It works by creating chains of amino acids that fold up to form biomolecular machines. 20 amino acids folding in nearly infinitely many combinations can form countless biomolecular machines, each with specific functions. \nThis structure is stable at the temperature as we know it. If it gets any hotter, the protein denatures. If it gets colder, the reactions are too slow. \n\nFurthermore, as you know, water is a very important for life. It's a nearly universal solvent, it's very viscous and thus provides easy transport, and it helps with reactions. Water has a very narrow temperature range where it's a liquid, between 0-100C. So it happens that life thrives at temperatures between those two ranges. ",
"I see a lot of answers here about how ludicrously high temperatures exist simply because molecules can always vibrate faster, but I feel like that doesn't really address your question - you even mentioned \"absolute hot\", which is effectively an upper bound just as 0K is a lower bound on temperature.\n\nThe fact is, the universe *did* exist at much higher temperatures in the past. Immediately after the big bang, the universe was near the Planck temperature (10^32 K). But space expanded, and as a result the universe cooled very fast.\n\nAt these temperatures, physics and chemistry are very different. For example, 10^32 K is hot enough to basically \"melt\" a proton; the particle that is in many ways the foundation for all of chemistry, is just a hot mess of quarks and gluons at very high temperatures. In fact, the temperature at which protons and similar particles can form is about 10^13 K - you can already see that we've made a lot of progress down from 10^32. And, the universe cooled to this temperature around 1 millisecond after the big bang.\n\nTo get more complicated things like heavy elements, stars, planets, galaxies... the universe needed to cool further. That's why the temperature we observe today is so much lower than many of the temperatures that are possible. But they did exist, for a short time, and basically even the most fundamental building blocks of chemistry couldn't exist until it cooled down some. ",
"Its because of water. Life as we know it more or less evolved to utilize liquid water. Liquid water happens between 0 and 100* Celsius so life as we know it fits nicely between 0 and 100*C.\n\nNow water is an awesome molecule. The molecular weight is tiny so in \"should\" be a gas at room temperature. Thanks to H2O's very strong polar nature it likes to stick together and pack itself down tight so it behaves like a much heavier molecule and is liquid at room temperature (along with a host of other awesome traits). This is also why water takes up less space as a liquid than a solid, unlike most other compounds its crystal form is larger (less dense) than its liquid form, so ice floats.\n\nIf water was less polar it would have a lower condensation point and we'd all live at a colder temperature naturally. \n\nChemistry just works real well at this temperature, particularly around the liquid phase of water. Its not too hot to cause complex compounds to burn and break down, its not too cold to cause our most abundant solvent (water) to turn solid. So chemistry at this temperature is very energy fluid (to say).",
"Celsius is based on water. Water freezes at zero degrees Celsius and boils at 100 degrees Celsius. Kelvin is based on absolute zero, which is zero molecular vibrations. Fahrenheit is a flawed scale based on human body temp (supposed to be 100 degrees Fahrenheit but he borked it up and yet we still run with it). Temperature is based on a measure of the average kinetic energy in a system.",
"You could look at a pot of water.\n\nThink of the water. Ignoring the fridge, it doesn't get much colder than room temperature-- that's about as low as it goes. \n\nIf I add some heat, it starts to boil! I don't have to add much for it to be useful for all sorts of awesome recipes-- making soup stock, boiling pasta, making potatoes. You name it, there's food that could use the kind of energy present in a pot of boiling water to do really great stuff!\n\nBut I can add a lot MORE energy... almost endlessly. Eventually that water moves on from a rolling boil to just steam blasting everywhere. It's not useful for cooking anymore because it's getting way too messy to force back into a confined space to be used. Worse sill, the more energy I put into it, the messier it gets, and the further away from dinner I am.\n\nSo the point is, only so much heat is needed to get past the stagnation of sitting still in order to start doing all the interesting stuff. Too much heat and all the interesting stuff becomes impossible because everything just flies apart.",
"Think of temperature as people walking. The slowest anyone can walk is 0km/hr. Our normal walking speed is arnd 7km/hr. In the grand scheme of things, that is pretty little considering things can go up to many thousands of km/hr",
"So to be clear, your asking why everything is so much closer to Absolute Zero then Absolute Hot?\n",
"Temperature is basically movement of small parts of the object (not sure if atoms or molecules, but that doesnt really matter). If you're at absolute zero, that means they don't move at all. If you reach really high temperatures (thousands of degrees) that means a lot of movement. \nBut by bumping into other objects, the surrounding objects will heat up just like if a ball bumps into a stationary ball, it will cause the stationary ball to move, the amount the moving ball slows down and the stationary ball speeds up depends on the relative mass of those balls, just like how much the temperature difference between a cold and a hot substance depends on their properties (i forgot the proper name for it, but every substance takes a certain amount of energy to heat up to a specific point). \nSo, it's hard to reach and maintain high temperatures, because you'd have to heat up everything even remotely close to you as to not rapidly lose all your energy to your cold surrounding (the bigger the temperature difference, the faster you lose the energy). \nTemperatures of millions of degrees are usually only observed at really small scales and for really short times. \nOn top of this, most of our materials just can't handle the stress of that much movement at the molecular level and would just tear themselves apart, turning into gas eventually and if sufficiently heated after that they would even turn into other forms of matter such as plasma and all kinds of things will happen because there is just a lot of energy in there.",
"Even if our chemistry or some type of order was possible at 1,000,000 degrees C, you could still ask the same question. The cold extreme will always have a minimum where matter doesn't vibrate, but the hot extreme is infinite. ",
"Your concept of what \"cold\" is would be the reason for your confusion. It's human nature to want to characterize \"cold\" as the opposite of \"hot,\" as if it had an entity of its own, a force, a mass, a side of things to be on. You want to give cold a presence.\n\nTemperature is merely how we perceive the level of energy of any bit of mass we can perceive. What we think of as \"cold\" is our brain's interpretation, the physical sensation we get, when we're in contact with something (air, water, metal, porcelain, your partners' feet in bed, etc.) with perceptible mass that has a level of energy that is low by our evolutionary standards.\n\nWe perceive something to be \"hot\" when the level of energy is high compared to our evolutionary standards. The fact that some objects are in existence that are energetic enough to be measured very high on arbitrary, human-created units of measurement is meaningless: cold is not the opposite of heat. All there *IS* is heat, or no heat.\n\nThink of it in terms of light and dark ... we tend to do the same thing with darkness, give it a characterization of its own, but all it really means is that there's an absence of perceptible light. Darkness has no presence of its own, and neither does coldness.\n\nAnother way to think of it is the emptiness in a half-full glass. You wouldn't assign that emptiness a value; it's simply the volume of space in which the fluid in the glass is not there. \"Cold\" is emptiness of molecular energy.",
"Temperature is roughly a measure of how much energy is in something. If you take away all the energy, you get absolute zero. If you put all the energy in the universe in one spot, you'd get the highest possible temperature.\n\nSo why is Earth so close to absolute zero? Simply because there is a *lot* of energy in the universe, and we don't need very much of it to survive. And if we had too much, we'd catch fire (plus, it's hard to keep energy in one place, so excess energy tends to escape). So Earth has a relatively small amount of energy because that's all it needs, and any extra just dissipates into space. (Unless pollution prevents it - this is the greenhouse effect.)\n\nCould life exist at much higher temperatures? Maybe, but it would take a lot more energy to maintain those temperatures, so it would be harder to survive. Also, most materials melt or burn or fall apart at high temperature, so it'd be difficult for the complex structures of life - such as DNA, proteins, brain cells - to exist. They'd all have to be made of chemicals with extremely high melting points, which are rare and like to explode when in contact with eachother.",
" > \"And why is it so easy to get things very hot ... [b]ut we still can't reach the relatively close temp of absolute zero\"\n\nIt is much easier to speed particles up than to slow them down. Adding energy is simpler than removing it.\n\nAlso, your question is one I've had before many times (along with relative size of objects in the universe). It is also what made me laugh when in The Flash they said Heat Wave's gun (Absolute Hot) canceled out Captain Cold's gun (Absolute Zero).",
"Dunno about \"everything\" being so cold... a lot of matter is in stars, and stars are pretty hot. As to the rest, mostly loose gas and a tiny amount in planets and planetoids, why wouldn't it be cold? To make something be not cold takes a source(s) of energy; absent proximity to an energy source, the natural trend of non-star matter is toward a state very near to absolute zero, I would guess.",
"It's just the way we measure it. Don't think of -273°C as a negative number- think of it as 0 K, which is what it is. 0 K means the atoms aren't moving at all. Higher temperatures means that the atoms are moving at higher speeds, and there isn't really an upper limit on speed. \n\n\nThink of it this way: We spend most of our life (relative to the Earth) moving at either 5km/h (walking) or between 50 and 110 km/h (driving). When you consider how fast light moves in a vacuum, you might ask \"Why is everything so slow?\" And the answer is that when you have a system of measurement that goes from zero to infinity, most of your stuff is going to be closer to zero.",
"Think of it this way: heat is movement. Molecules can speed up all they like, changing form like ice to water to steam, so an increased heat is alqays possible. You can always go faster (until the speed of light). But slowing down isn't infinite. You can't go slower than 0mph for example (negative velocity is still positive speed). So the absolute zero, 0k Is when all molecules freeze completely. To this day we have not been able to find something that cold of to make something that cold. We've gotten astoundingly close, but never reached it. \n\nNow the *reason* 'everything' is closer to the cold limit than to the hot as due to a thing called Entropy or chaos. A quick background of entropy, in physics and chemistry, is that things like to be in a state of as little entropy as possible. If you'll imagine a cube of ice, it's only one cube. One thing to keep track of. If it shattered, thered be more to 'keep track of' as all the shards are independent. This is a higher level of Entropy. Also, if you heated the ice up, it would become water, which flows and splashes and cligns to things and such. This is an even higher Entropy level. If it were a gas, it would be higher and higher etc. Basically, the more molecules move around, the more chaotic things get. \n\nThink of being a gym teacher in a large room full of kindergartners. If those kids were all running randomly in every direction, you can imagine the chaos you would be dealing with. Higher level of Entropy. If they were calmer, maybe walking in a line, they would be easier to deal with and less chaotic. \n\nAs I said before, things like to be at a lower level of Entropy, which means getting colder. Thats why most of everything we deal with is extremely closer to the cold barrier than to the heat barrier.",
"Imagine atom is this little Timmy. Well, Timmy could go as slow as standing still. Can he go slower than that? No. So this is where we established the absolute zero where Timmy stands in one place without moving. But can he go faster? Sure, he will walk. Faster? Yeah, he runs? Faster? Well, he travels in a car. Not enough? Put him in a plane. Timmy still wanna go faster? Well, tell that fucker to shut up and stop being a lil' bitch somebody is about to slap the shit outa him. This is how Timmy could possibly go faster and faster without limitation. But life is a bitch and so at a certain point, Timmy's parents will lose their shit and ground the lil' kid and possibly kill him to make another smarter one. so there is a limit in which Timmy couldn't ask for more. In order to stay stable, organism need a stable environment, anything that's too hot or too cold will kill them, just like animal getting burned alive or such.",
"I'm pretty sure it's because cold is just a lack of heat. You can't \"add\" cold, you can just take away heat. \n\nWhat's the lowest heat you can have? Zero. What's the highest heat you can have? Infinity.",
"After reading the first few top posts, I didn't read a satisfying response. \n\nAs simple as I can put it, there is no source for cold, only a source for heat. You can make things cold by taking away heat. Not vice versa. ",
"Temperature is a measure of the amount of kinetic energy particles that make up something has. Kinetic energy is \"the energy of motion.\" So on a basic level, if all the particles stop, they have no movement, therefore no kinetic energy and the lowest temperature possible, this is zero on the Kelvin scale (or -459.67 F or -273.15 C depending on which scale you use.) As for the highest temperatures, particles can always move faster (not taking in Einstein and relativity) so the temperatures can always go up.",
"Don't think of 'hot' and 'cold' as two seperate variables, but rather that 'cold' is what's achieved with the absence of heat. Heat is the variable, and absolute zero is the complete absence of heat.",
"Temperature is based upon the movement of subatomic particles; the slower they're moving, the \"colder\" we perceive things as being. \n\nYou can't get slower than \"no movement,\" so that's absolute zero. We monitor things by bouncing other things off of them, so we can't get all the way to absolute zero because the act of monitoring the temperature is enough to elevate it. We've come within something like one sixteen-millionth of a degree, though.\n\nAbsolute high temperatures are theoretical. We don't really know a lot about them because the kinds of temperatures that were present around the formation of the universe don't exist anymore. \n\nAlso, they may or may not reflect actual \"maximum\" temperatures, meaning that the laws of physics might conceivably *allow* for higher temperatures (say, if there was more mass in the universe).\n\nWe are only familiar with life on Earth. Life on Earth evolved to require liquid water. Liquid water requires a certain temperature range, so we require that temperature range. \n\nIt is conceivably possible that life exists in wildly variant forms. There could be energy-beings inside of stars, for all we know. There could be giant space amoebas. Until we find something living, and recognize it as such, all we've got to go on is what's here.",
"I think that's kind of like saying everything in our world is really, really quiet because there is no maximum for sound and the minimum is 0db. ",
"\"I guess my question is, why does life as we know it only exist in such extreme cold?\"\n\nWe currently only know of life on one extremely small and isolated area of the universe. When considering all the possible environments where different forms of life could evolve, we just haven't tested a large enough sample area to actually conclude that no other forms of like are out there.",
"Temperature is proportional to the average velocity (squared) of the atoms/molecules you are measuring.\n\nAbsolute zero is literally the temperature it takes for the atoms/molecules to stop moving in any way (that includes rotation and vibration).\n\nA better way to understand this is that temperature is proportional to the average kinetic energy (energy related to the motion of matter) of whatever matter you're measuring.\n\nPlanets (where life exists) are surrounded by a vacuum and thus is closer to that absolute zero than it is to the absolute hot.\n\nIf it was too hot, then the atoms and molecules would be too unstable due to its energy being too high and the molecules will be split into its constituent atoms and the atoms themselves will be ionized (their electrons will be shredded off).\n\nSince life can only exist with stable molecules (meaning that they don't fall apart), you need a temperature that will keep them together (but not too cold so that nothing happens). Remember, at a 100 C water is vaporized. With no liquid water, there's no life (at least Terran life).",
"Absolute zero is zero energy. That is the point where all energy in the molecules and atoms of matter is gone. Zero. Which is impossible. You can come close to having zero energy in a sample of matter, but can't quite remove every bit of energy. \n\nOn the other hand, there is no upper limit on the amount of energy in matter, thus there are stars with temperatures of millions of degrees in the core. ",
"\"why does life as we know it only exist in such extreme cold?\"\n\nDid anyone answer this?",
" > wouldn't it mean that life and everything we know as good for us, is ridiculously ridiculously cold?\n\nThis concept is only difficult to come to terms with if a person believes the universe was created for humans.",
"Entropy. Cold isn't an energy, it's a lack of it. Energy, like water, tends to move from areas of high concentration to lower concentration. In other words heat something up, and that heat gets radiated and absorbed by everything around it until it's the same temperature as everything else. \n\nIt's akin to saying why does fast only have a limit of the speed of light, but slow can only lead to stop. You can't stop any stoppier than you can when you're stopped. But if you're going fast you can always go faster, until you become relativistic. \n\n**edit**Entropy in this instance having to do with the second law of thermodynamics",
"Exciting things are hot. Placid things are cool. Some parts of the universe are exceptionally hot and exciting. Imagine living life as a plasma demon on Sol. ",
"ok so ill give a non scientific answer. Humans created the term \"temperature\" and it's scale. We scaled it to our human needs.",
"It depends how you think about temperature.\n\nI'm gunna share a crazy thought, hopefully it will explain my above point. Recently I've been thinking: what if temperature was backwards (it makes some chemistry easier, and wikipedia says some physics make more sense if we do this). So if instead of measuring temperature we measured 'inverse temperature'. \n\nIf we did that and still had 100 degrees between freezing and boiling (I'm gunna call it °P), then it would be the other way round:\n\n100 °P is freezing, 0 °P is boiling. Your fridge might be 93 °P, your freezer at 130 °P, your oven -50 °P, a 25 °C day would be 69 °P. The coldest temperature ever reached is 1×10^14 °P, while infinite temperature is just -273 °P. The temperature of space (CMBR) would be 337 °P. So from this perspective life exists as middling 'inverse temperatures', about halfway between space and the temperature of the sun (which is very close to -273 °P). We can get things *very cold*, but not very hot: we've never reached 'absolute zero inverse temperature' (this is infinite temperature), let alone managed to get down to negative temperatures (which are theoretically possible in some systems).\n \nSo with a change of perspectives you end up asking the opposite question.\n\nDoesn't answer your question, but I hope it is interesting (and makes sense. I'm not always very good at making sense).\n\nEdit: got hot and cold the wrong way around, also clarity.",
"Because the points are made up and the games don't matter.\n\nWhat I mean by this is the Celsius scale, for example, was based off of freezing and boiling points of water. If another substance had been chosen then the scale would be completely different. Therefore, from a theoretical aspect, the numbers are completely arbitrary. \n\nWe are only on the 'cold' side because h2o is on the cold side. If Hydrogen had been used as the base the we would be further up the 'hot' side.",
"The average temperature of the universe is around 2.7 K, and we live at temperatures of > 100 times that, so why do we live in such an extremely hot environment?\n\nDescribing our temperatures as extremely cold or extremely hot is extremely arbitrary, it all depends on your point of view.",
"O kelvin is just the temperature at witch atom movement stops. Our zero points in our systems were set to benchmarks such as the freezing point of water ( Celsius ). Temperature is the intensity of atomic movement, as far as I understand. There is no maximum to movement. If you get to ridiculous levels of temperature, it gets kinda wacky with plasma. Atoms basically start to fall apart.",
"Think of it like a car. A car can't get slower than not moving. It can't stand still even more. \n\nBut it can accelerate. Cars can go pretty fast. Even 200 mph. But all cars have a stopping point of 0 mph.\n\nThe average speed limit of a road in the U.S. is 45 mph. Say that's earth's surface temperature that we experience. Now say (not to scale) the surface of the sun is 250mph. We can build cars that go that fast. We could strap a jet to a car to make it go even faster. \n\nBut we can't make a car go slower than 0 mph",
"Technically from a thermodynamics point of view cold doesnt exist. Only the absence of heat. Im sure someone will rip me apart for this however. Oh well. ",
"There is no cold, only heat and the absence of it.\n\nMuch like how there is only light and the absence of it.",
"The question has been answered but I'd just like to add,\n\nWe do live quite close to absolute zero, but when you're upper limit is in the trillions, the difference between 100 degrees and 10000 degrees is relatively minuscule. So even if we were accustomed to a much higher range of temperatures, you could still pose this question. I guess my point is, very large numbers can still be relatively small because numbers go on forever.",
"Think of thermal energy as puddles of a liquid on the giant bathroom floor that is our universe. Think of the depth of a puddle as a rough analog of temperature. Given that there isn't a lot of liquid (i.e. most of the bathroom floor is empty), you'd expect mostly shallow puddles, rarely a few deep gobs of liquid, and a general tendency for the liquid to spread out until you have a shallow film of liquid all over your floor.\n\nThis is a crude analogy for the principle of entropy, and explains why most things are fairly cold.",
"No we are perfectly in the middle. As the 4 times Reddit gold awarded post stated: we can't reach the absolute 0. We can just go as near as possible maybe 10^-5 apart from 0 Kelvin. Next step is 10^-6. What's the difference between those numbers? Basically nothing. Now take a look at the hot side. Maybe the sun is 10^5 and maybe more inside it is 10^6. what's the difference? 10 times this freaking hot number. This makes you think hotness scales much more. But we are living at approximately 10^2 which is in the middle the further you go in both sides. \nTldr think logarithmic "
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] |
|
2tqoio
|
how come the third rail on subway systems doesn't short circuit when it gets wet?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/2tqoio/eli5_how_come_the_third_rail_on_subway_systems/
|
{
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"co1fv5i",
"co1h27v"
],
"score": [
3,
2
],
"text": [
"1. Water on the rail itself doesn't short circuit, as the rail is more conductive than the water.\n\n2. The water doesn't bridge between the third rail and a suitable ground. It might drip off, but it won't form a continuous path like a wire very easily.\n\n3. Water is an awful conductor, so outside of very high voltages such as lightning strikes, it doesn't tend to carry a charge very far.",
"Short circuiting is when water connects two parts of a circuit that aren't supposed to be connected. The water would have to form an unbroken path between the third rail and another part of the same circuit with a different voltage "
]
}
|
[] |
[] |
[
[],
[]
] |
||
2a9wih
|
What major new inventions/technology were developed or poularized around 1860 to 1890?
|
And is there any good general source for a timeline of major inventions throughoutt history?
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/2a9wih/what_major_new_inventionstechnology_were/
|
{
"a_id": [
"citcgat"
],
"score": [
2
],
"text": [
"You're describing the Gilded Age and part of the Second Industrial revolution in most textbooks. This would have been a period that focused on industrial processes and the \"first\" examples of consumerism with plenty of examples of advertisements for tobacco and alcoholic beverages to different groups in society. I think you can make a fair argument that this period was the one in which modern firearms were developed. You can also see the beginnings of mass production of cheap consumer goods like tinned beef and national breweries. I don't know of any good encyclopedias for inventions during a specific time period, but here are a few I know of:\n\nFirearms: Smokeless powder, brass cartridges, lever action/bolt action firearms, high explosives such as dynamite, etc.\n \nMedicine/Sanitation: the Pasteurization process, canning, refrigeration\n \nIndustry: the Bessemer Process for steel, "
]
}
|
[] |
[] |
[
[]
] |
|
54l883
|
if an ambulance is called to a casualty, but then sees one happen in front of it or is close by another, which one do they go to?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/54l883/eli5_if_an_ambulance_is_called_to_a_casualty_but/
|
{
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"text": [
"The ambulance drivers and paramedics don't make that decision. A dispatcher tells them where to go. If another emergency needs attention, dispatch will send another emergency response vehicle to attend to it.",
"EMT here. If there are multiple patients on one scene we will triage and attend to the most critical patient first. Of course in that scenario dispatch will likely already know there are multiple injuries, so another truck should be on the way. If not we let dispatch know. \n \nIf you mean what happens if we see a car accident on the way to a different call then the best answer is it depends. \n \nDuring a blizzard in 2009 we got dispatched to a car accident. On the way to that accident we noticed another. After quickly making sure there were no injuries there, we continued to the original accident. There was only one person with injuries. As we're transporting him, we see another crash happen, and let dispatch know they need an ambulance. Then a multi car pile up at the intersection outside the ER. No injuries there either. 4 car accidents in 30 minutes. \n \nI've stopped to evaluate a vehicle crash while I had a patient. Before you get the pitchforks, my patient didn't need an ambulance, but refusing to transport even a BS patient is considered abandonment in the state I worked in. I stayed with the \"spider bite\" patient while my partner evaluated the accident we found. ",
"Laws vary by location. They will generally dispatch another truck if the patient they are currently transporting is critical. It also depends on the skill mix of the providers on board and ETA of other truck. Most services have restrictions on how many and what type of patients one truck can transport. There are also restrictions on how many patients one provider can care for. \n\nIn general, if a provider makes patient contact and the patient doesn't refuse transport, the provider is obligated to care for that patient until they turn over to a higher level of care (RN, NP, MD, etc...). ",
"If an ambulance is assigned to a call they are required by law to respond to it. This is called \"Duty of Care\", and is covered in chapter one of every first responder, EMT, AEMT or Paramedic course in the US. Outside the US I have no idea. \n\nThere is no choice. Doing anything else is at least a tort (civil liability), and in some cases would be a criminal act. At the very least they would lose their job, their license and their national registration.\n\nIf they see something on the way they will call it in.",
"I recently was a bystander in such an event. I was cycling along a bicycle lane and in front of me another cyclist crashes into a woman. Anyway the woman was inimitably standing but the cyclist had hurt his leg and his shoulder and was unable to continue cycling and walking was painful. He also hurt his shoulder. Anyway we call in a ambulance and it took a 90 minutes to arrive. So when the ambulance arrived they explained that this call had been assigned low-medium priority due to in all likelihood a non broken leg and a dislocated shoulder not being as high a priority and the first dispatched ambulance seeing a accident which they decided to act on first. "
]
}
|
[] |
[] |
[
[],
[],
[],
[],
[]
] |
||
1no0ci
|
What gravitational forces (from outside of our solar system) are acting on our Sun?
|
To be more specific.... The sun revolves around the center of our galaxy, but where is it feeling a gravitational pull from: Is it the actual galactic center or is it kept in line more by the influence of surrounding stars (like some kind of gravitational hand-holding)?
I'm sure I could have worded that better, but I'm no astronomy student. I've just always been fascinated by it all. Thanks in advance for your explanations. I love this sub!
|
askscience
|
http://www.reddit.com/r/askscience/comments/1no0ci/what_gravitational_forces_from_outside_of_our/
|
{
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"cckoi5o",
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"text": [
"The sun is feeling the mean gravitational field of the entire galaxy (all stars) + the dark matter than is actually dominant part by mass. So the sun is feeling primarily the gravitational attraction of the dark matter which is homogenous in distribution + the stars, and since the galactic center is much denser than the rest, you can neglect anything beyond it.",
"Unnecessary answer:\n\nThe sun experiences gravitational force from all objects in the universe whose gravitational force (which is assumed to spread at the speed of light; but if the sun were to move into some direction all of a sudden, we'd immediately experience that effect, because somethingsomething layman abovemyhead) has already reached it."
]
}
|
[] |
[] |
[
[],
[]
] |
|
a4yuo3
|
Did eyes evolve only once on Earth? Is there something about the small band of "visible" light that makes it optimal for eyes to evolve to see? Or is it just a coincidence that most animals see in the same spectrum?
|
I have heard of animals that see infrared & ultraviolet. But they all see (or so I think) the same frequency of light we see. Would an alien eye be more or less likely to see nothing in our "visible" band of light because it sees a higher or lower frequency? If eyes evolved once, it may be that the commonalities are just happenstance and not due to some inherent quality about the small band of frequency of light we can see.
|
askscience
|
https://www.reddit.com/r/askscience/comments/a4yuo3/did_eyes_evolve_only_once_on_earth_is_there/
|
{
"a_id": [
"ebinbz3",
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40,
11,
2,
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"text": [
"Eyes are a very very helpful adaptation. Any type of sensory perception of light is useful. There are a couple cases of convergent evolution regarding eyes. I remember a cool video about their evolution, ill try to find it!\n\nJust found it: [eyes ](_URL_0_) \n\nI love this because its so hard to think about how something so complex evolved! \n\nEdit: bonus clip about the[eyes of a manis shrimp](_URL_1_) , the coolest animals ever! ",
"\"eyes\" evolved independently in an enormous number of species.\n\nOr more accurately, the basic parts of an eye developed waaay long ago in the species that formed the base of a lot of different genetic trees.\n\nLong before the dinosaurs, or before most mammals existed.\n\nAnd this has to do with what the most basic form if the eye is, a cell that can determine light from dark is to most people an \"eye\" and that has evolved near the base of almost every family tree.\n\nIt evolved because the sun is the basis of almost all life on Earth.\n\nFrom that simple beginning most animals have developed eyes as at least a secondary sensory organ.\n\nBut those eyes are well different from each other, some only see certain colors, some see movement, some work in low light, some are farsighted etc etc.\n\nThe basis of all of them is pretty similar, because the base evolved we'll before \"human\" and \"cat\" evolved to be separate.\n\nThe original mammal had something that we might recognize as \"eyes\" and those formed the basis of what all the mammals (well, the vast majority) would modify into the eyes they have today.",
"You're a bit confused as to what \"frequency\" means. Frequency is the reciprocal of wavelength, and we use wavelength for light, because frequency is very clumsy when you get into petahertz.\n\nVisible light runs from roughly 800 nanometers to 450 nanometers. As light gets shorter wavelength (higher frequency) it becomes more energetic, to the point where UV is energetic enough to be mildly hazardous in natural doses.\n\nA human retina can see near-ultraviolet (to about 390 nm), but it's filtered out by the lens and cornea. People who've had their lens replaced can see some of the patterns in flowers invisible to the general population.\n\nVisible light has a very special place in the EM spectrum, so biology, even alien biology, would probably use it somehow. It's short enough wavelength to resolve fine detail, most gases and liquids are transparent to it, but it's not energetic enough to cause chemical damage to a biological detector (e.g. a retina). These are the result of laws of physics, which are the same everywhere.\n\nInfra red is absorbed quite strongly by many chemicals by vibrating their bonds (IR spectroscopy works this way), including chemicals in the air and water, so it doesn't pass through air or water very well. Ultraviolet is not only hazardous, but also exhibits very extreme scattering in air. In the same way the sky is blue due to Rayleigh scattering of blue light, UV is scattered even more. This is why insects (and hawks) use it only for relatively short range vision: UV has a lot of \"glare\" about it thanks to atmospheric scattering.\n\nLight in biology is so useful that photoreceptors evolved multiple time (even plants have them) although all true eyes in vertebrates have the same ancestral structure. It's so useful it was never lost but at the genus level in specific habitats, like blind cave fish.",
"Eyes/camera vision evolved multiple times, a good example of this is cephalopod eyes, which unlike vertebrate don't have blind spots because of the way the retina is innervated.\n\n & #x200B;\n\nAlso, the output of the sun peaks on green, which is sort of why plants are green - because they would get burned if they absorbed the green light. The suns spectrum is in red and blue also, which is why it appears white to us humans - because we have red, green and blue sensitivity.\n\n & #x200B;\n\nId imagine that if aliens also evolved camera vision it would be centered on or near the peak wavelength emission of their host star. Additionally, the atmosphere of their planet would also have some effect on the hypothetical aliens' spectral sensitivity. The atmosphere might filter out certain frequencies of light. An example of that is the blue sky sunsets on mars, whereas on earth sunsets are usually orange or red.\n\nSome stars are very blue, with a lot of ultraviolet light being produced alongside the visible and some infrared, and so the aliens might have spectral sensitivity to ultraviolet.\n\n & #x200B;\n\nWho knows though, look at all the animals on earth, some can see in infrared while others can see in ultraviolet, some don't even see but they hear and feel and smell their environments. \n\n & #x200B;",
"So eyes evolved many times as already mentioned, but a very curious thing is that the photoreceptor used in all eyes appears to have evolved once. All \"eyes\" use a descendant of this same photoreceptive protein.\n\nThe only arguable exception is the \"pit organ\" in some snakes, but this is really a directional heat sensor rather than an eye - the infrared rays do not directly excite any receptors.",
"Off the top of my head, one really fascinating example off the top of my head (forgive me if details are off) is the separate evolution of the human eye and eyes of cephalopods like octopi and squids. The human eye evolved with a blind spot where your optic nerve goes through the back of your retina blocking a small portion of your vision. You don't notice it because your brain fills in the missing bit based on what is surrounding it. If you haven't ever heard about your blind spot [check this out](_URL_0_). \n\nCephalopods don't have this problem because their eye evolved so that the optic nerve is behind the retina if I remember right. Both human and cephalopod eyes are pretty darn effective compared to the majority of the animal kingdom, however, they evolved completely separately and have a couple major differences. "
]
}
|
[] |
[] |
[
[
"https://m.youtube.com/watch?v=qrKZBh8BL_U",
"https://m.youtube.com/watch?v=IiVKwpWXDic"
],
[],
[],
[],
[],
[
"https://visionaryeyecare.wordpress.com/2008/08/04/eye-test-find-your-blind-spot-in-each-eye/"
]
] |
|
2ict3r
|
why does binge gaming make me feel like an angry zombie irl?
|
I've noticed over years of gaming that I cannot let myself binge over a weekend playing anything too intense because it has noticeable effects on my real life. After these long gaming sessions i am:
* unable to concentrate on pretty much anything
* easily annoyed and grumpy
* completely lacking interest in anything.
Once I start playing again, all of these negative effects seemingly go away and I'm able to play at a high level unhindered.
If I have been gaming and notice these feelings, I know that I have become an angry zombie for the rest of the day.
What's causing these feelings and why is it easily reversed when I start playing again?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/2ict3r/eli5_why_does_binge_gaming_make_me_feel_like_an/
|
{
"a_id": [
"cl0z4g2"
],
"score": [
2
],
"text": [
"I hate to say this, but you're a gaming addict. If you take small, regular \"hits\", you're ok, but if you take too big of a hit, and then try to jump off you go into withdrawal symptoms, and what fixes those? Another hit."
]
}
|
[] |
[] |
[
[]
] |
|
88cl63
|
How gory was Napoleonic era warfare
|
I mean that surely it was not as bloody as 20th-century warfare as in hands and bits of flesh and shrapnel flying everywhere but I was just wondering, how bloody/gory it was
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/88cl63/how_gory_was_napoleonic_era_warfare/
|
{
"a_id": [
"dwnin8q"
],
"score": [
5
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"text": [
"Well you thought wrong, dumbass! \n\n**5 TIMES DUDES GOT REKT IN NAPOLEONIC WARFARE (#4 WILL SHOCK YOU!)**\n\n#1 *These Colors Don't Run!*\n\nSo during the Waterloo campaign, this British battalion had to stand in the open under French cannon fire. This colors sergeant, will **brass balls,** can see one pointed straight at him; he even sees the shot flying straight for him. He thought about ducking for a moment, but decided not to, and held the colors high, standing tall. As it happened, the shot didn't kill him, but it did decapitate the four men of the file on his right. \n\n#2 *Eye Popping!*\n\nAt the Battle of Auerstadt, Napoleon's badass-in-chief Marshal Davout was leading his isolated corps against the main force of the Prussian army, the same guys who had trounced the French in the Seven Years War. But, they just throw one isolated division at Davout after another, with all the impact of those wet toilet paper balls high school kids try to plaster the bathroom ceilings with. At one point, the Prussian leader, the Duke of Brunswick, tries to lead a regiment of grenadiers into the shit, but he gets shot in the head and loses both his eyes for it! What's worse, it takes almost a month for him to die this agonizing death! Ouch!\n\n#3 *Good thing he had his armor!*\n\nThe French cavalry of the Napoleonic Wars had a long tradition of beating the shit out of people, and the best of the best were their heavy cavalry, and the best of the best of the best were their carabiniers a cheval. These guys rode the biggest horses, and in an age of muskets and cannon, wore honest-to-god breastplates as part of their uniform. However, one poor carabinier, François Antoine Fauveau, discovered exactly [why](_URL_4_) heavy armor had fallen out of fashion with the rise of gunpowder. It doesn't take much imagination to picture what the poor guy looked like after the cannonball's astute instruction.\n\n#4 *The boy stood on the burning deck...*\n\nSo while Napoleon was off making the Mamelukes his bitches under the fuckin pyramids and cucking one of his men, turns out Nelson was about to make Napoleon his bitch! You see, Egypt is across the ocean from France, and Napoleon had to take a boat to get there. At this time, the British had what we call a Badass Navy (which they used to find a letter from Napoleon's wife admitting to cucking him -karma!); they let Napoleon slip past them to get to Egypt, but there was no way they were going to let him out. They jumped the French fleet in Abukir bay, and basically prison shanked them. The biggest and baddest boat in the French fleet, *l'Orient*, caught fire, and when the fire got to the gunpowder, it went off like a firecracker. Here's where it gets *fucking badass*. Y'see, boats are full of seamen (teehee), and when they explode, the seamen go with it. Not only were British boats set on fire from all the flaming wreckage, they got pelted with raining body parts from all the French who got blown up! Badass!\n\n#5 *Waterloo again!*\n\nAt Waterloo, the British were led by Certified Grade A Badass the Duke of Welligton, who had for his cavalry commander the Earl of Uxbridge. During the battle, a cannonball struck his leg and all but tore it off. The man exclaimed to his commander, \"By God sir, I've lost my leg!\" Wellington replied, \"By God sir, so you have!\"\n\nLastly, I'll just let these pictures speak for themselves; these are sketches by one Sir Charles Bell, depicting the wounded soldiers of Waterloo [caution, not safe for work].\n\n_URL_0_\n\n_URL_3_\n\n_URL_6_\n\n_URL_5_\n\n_URL_1_\n\n_URL_2_"
]
}
|
[] |
[] |
[
[
"http://blog.europeana.eu/wp-content/uploads/2015/06/Soldier-wounded-at-Waterloo-with-right-arm-missing.jpg",
"http://blog.europeana.eu/wp-content/uploads/2015/06/Soldier-with-left-arm-missing-bandaged-head-with-quill-in-right-arm.jpg",
"http://blog.europeana.eu/wp-content/uploads/2015/06/Soldier-suffering-from-head-and-facial-injuries.jpg",
"http://blog.europeana.eu/wp-content/uploads/2015/06/Soldier-suffering-from-head-wound.jpg",
"https://imgur.com/tGFRIJZ",
"http://blog.europeana.eu/wp-content/uploads/2015/06/Sabre-wound-to-abdomen.jpg",
"http://blog.europeana.eu/wp-content/uploads/2015/06/Soldier-with-missing-arm-lying-on-his-side-grasping-a-rope.jpg"
]
] |
|
1ipsqy
|
During WWII did the British government ever ask for "royal subjects" from all over the world to report for military duty? Did some just show up and volunteer?
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/1ipsqy/during_wwii_did_the_british_government_ever_ask/
|
{
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"cb6v9jn",
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2,
6
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"text": [
"There was the Empire Air Training Scheme (it has different names depending on which country you're from) which was a training programme for aircrew developed by the United Kingdom, Australia, Canada, New Zealand and South Africa. Aircrew from the dominions would receive initial training in their own countries before going to Canada for more advanced training. At the completion of their training these pilots could be assigned to the Royal Air Force but still belonged to the air force of their own country. When assigned to the RAF they could would be assigned to a squadron of their home country under RAF control which used RAF aircraft. ",
"_URL_0_ \n\nThe commonwealth contribution was enormous, of the over eight and half million personnel raised under the British Empire around three and half million came from outside the British isles. \n\nWhether it was through conscription or voluntary was dependent upon time and place. \n\nIndia contributed two and a half million volunteers which was the largest volunteer army in history. \n\nPoland contributed many volunteers despite not being part of the commonwealth, many of those would later become British citizens. \n\nAustralia introduced conscription partially due to the fact that they perceived Japanese activity to be a threat to them directly, as well as due to close ties with the U.K. At first it was only to protect Australian territory but after Pearl harbour and various other events on the Eastern front they allowed some of these conscripted soldiers to fight in Europe. \n\nThat's just a few examples, the role of the commonwealth in WWII was massive and complex. \n\nAnd yes the British government did very actively solicit for volunteers in commonwealth countries. \n \n\n\n"
]
}
|
[] |
[] |
[
[],
[
"http://www.bbc.co.uk/history/ww2peopleswar/timeline/factfiles/nonflash/a6651218.shtml"
]
] |
||
2or2ef
|
why can't the interest rate set by the boe remain low indefinitely?
|
I keep hearing from pundits that it must be raised eventually. I don't understand why.
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/2or2ef/eli5_why_cant_the_interest_rate_set_by_the_boe/
|
{
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"cmppbje",
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"text": [
"Low interest rates can cause the economy to \"overheat\". People will take too many risks with the cheap loans. In bad times people are trying to protect what they have so we need them a bit more risk taking. In good times we want people to be more cautious.\n\nThe economic problems of the last decade were caused by companies and individuals taking too many risks because the good times made them think they were invincible. ",
"When interest rates are low people (and companies) tend to spend more money or invest in capital because the opportunity cost **which is basically the cost of the next best option** (of saving their money to earn interest from a bank instead of trying to create income from business expansion/ventures) is much lower.\n\nWhen interest is at 1% for a company, they are barely even making any REAL money because inflation could be much higher, but if you open a new store you could make an 8% return on your money.\n\nSimilarly for people, when interest rates are at 1% but inflation is at 2%, whats the point in saving your money with the bank when it's real value is decreasing year after year because inflation is eating it away . You might as well go on holiday or buy a new TV / pair of shoes since your money is worth less every day in the bank anyways.\n\nThis causes the economy to spend spend spend and it can \"overheat\", you see too much consumption in the economy and when the total level of consumption exceeds the total level of supply (and there are time-lags between increases in consumption and increases in supply), you find that companies realise they can charge EXTRA money for the same good and people will still purchase it because you have excess demand for these goods (12 people trying to purchase 10 items).\n\nThis raising of prices is called \"Inflation\", this kind is more specifically, \"Demand pull inflation\".\n\nNow when the government raises interest rates, suddenly saving your money looks much more attractive to both individuals and businesses because why risk creating a new plant or factory to make a MAYBE 8% return on your money, when you can just leave it in the bank and it will generate 3.5% return on its own.\n\nIt requires no effort to do, and theres no chance of your \"bank interest gathering business\" failing.\n\nSimilarly, consumers see that their money, when kept safe in the bank is churning out 4% of its total value in *extra * money every single month so why would they go and purchase a new car or TV when their money is growing in size from doing nothing.\n\nHowever when interest is high, saving tends to be high and therefore total consumption in the economy *decreases*, (when people are saving, the demand for new clothes from Hollister decreases) and therefore people lose their jobs etc, companies close down stores and then the government has to give all of these people unemployment benefits and the government is bringing in *less* tax money because people aren't employed.\n\nFor these reasons the government, needs to carefully juggle the level of interest in an economy because they don't want to have a recession or a super-boom period.\n\nIf I've missed anything or you have any questions just give tell me and i'll be happy to attempt to answer it.\n\n"
]
}
|
[] |
[] |
[
[],
[]
] |
|
7z82pl
|
how do companies like that popular company selling evs or that other popular ridesharing company lose billions of dollars each quarter and yet manage to avoid bankruptcy? not only that they are viewed as companies which have a bright future in front of them?
|
Pretty much that, had to avoid mentioning the names of those 2 companies because it got taken down by Automoderator the first time around .
So I sort of understand how corporate bonds work, but those companies have been around since the early 00s and surely time to pay back their initial bond sale came and went, how could they do that if they managed to lose money every single quarter? Did they just sell more bonds to raise money to pay bonds which matured?
Also how is that possible that constant optimism (I'd say optimism is an understatement) , more like "destined to succeed" attitude surrounds those companies? Investors and the general population seem to think their dominance is inevitable! Am I missing something? Please don't use strictly financial terms or ELI5
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/7z82pl/eli5_how_do_companies_like_that_popular_company/
|
{
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"dum03sv",
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"text": [
"They spend money provided by investors, who buy a piece of the business hoping to cash in on *future* profits.",
"They’re not profitable yet due to expansion or growth. But they do make some money. So they generally have a large cash reserve or find new investors when they need more money. Once they run out of money then they’re basically finished unless they turn profitable. ",
"First off, they don’t use corporate bonds. They take on investment from venture capital firms in return for equity, or ownership stakes in the company. They take on investment at various times based on current valuations and financial needs. Additionally, Tesla has gone public and sold stock to the public.\n\nThis money is invested in growing the business today to a scale such that it will be profitable in the future. It take time and money to design cars, build factories, etc. so when they build a few cars and spend a lot on building a giant battery factory, they lose lots of money. But one day, the factory will be complete, and they will be able to make 100x the number of vehicles annually and they will become profitable.\n\nSimilarly, Uber spends lots of money on regulatory and legal fees to be allowed to operate in various cities, as well as money on bonuses for new drivers and discounts for new riders to build up a large enough network of each so that riders can get rides when they need and drivers can make money by driving. Once this system matures, the spending goes way down while ridership continues to grow and profits become feasible.\n\n"
]
}
|
[] |
[] |
[
[],
[],
[]
] |
|
1g9qlw
|
Can the magnetic field of the Earth be "thrown off"?
|
I was reading [this article](_URL_0_) where it says that they are capable of producing a magnetic field of up to 11.8 Teslas. The Magnetic Field of the Earth is only 30-60 microTeslas. Will the earth's magnetic field be affected by a magnetic field this large?
|
askscience
|
http://www.reddit.com/r/askscience/comments/1g9qlw/can_the_magnetic_field_of_the_earth_be_thrown_off/
|
{
"a_id": [
"caiiy0u"
],
"score": [
3
],
"text": [
"In the far field of a magnetic dipole the field is proportional to the inverse cube of the distance so it falls off very quickly. Say the leakage field 1 meter from the magnet is 1 Tesla. By the time you're 100 meters from the magnet the field will be 1/100^3 or one millionth of the strength at 1 meter, already far weaker than earth's field."
]
}
|
[] |
[
"http://www.iter.org/mach/magnets"
] |
[
[]
] |
|
2fo41w
|
Why are blacksmiths called blacksmiths?
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/2fo41w/why_are_blacksmiths_called_blacksmiths/
|
{
"a_id": [
"ckb6pid"
],
"score": [
5
],
"text": [
"They smith the black metals (iron) as opposed to white(tin), silver(flatwear and other objects), gold(jewelry). It comes from the color of the final product. "
]
}
|
[] |
[] |
[
[]
] |
||
256mt2
|
how do they launch space ships from the moon back to earth?
|
On earth they have all this fancy equipment, huge crews, etc. On the moon they don't. Plus don't they drop a bunch of engines or something on their way? So how does it work?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/256mt2/eli5_how_do_they_launch_space_ships_from_the_moon/
|
{
"a_id": [
"che7nvz",
"che7psb",
"che8c80"
],
"score": [
4,
2,
2
],
"text": [
"The moon's gravity is much weaker than the earth's, and there's no atmosphere to offer up any resistance, so they didn't need as much thrust to escape the moon's gravity well. Considering that, the lunar lander was designed to launch from the moon using its landing gear as its platform. once it was in orbit, the lunar lander rendevoused with the command module which remained in orbit, the command module had another rocket attached to it to bring the crew back to earth.",
"Three guys on the mission. The part that gets as far as the moon has a Command Module and a Lunar Excursion Module. This assembly gets into lunar orbit. Two guys get into LEM which separates from the CM and go to the surface. One guy stays in CM in lunar orbit. After a few days golfing on the surface, the LEM guys do a burn to blast back out to lunar orbit and dock the LEM. They crawl back into the CM. IIRC the LEM is dumped prior to the burn to leave lunar orbit and the ride back to Earth.",
"I don't mean to piggy back your question but how, once in space, does any thrust from a rocket result in motion or acceleration if that rocket is in a vacume."
]
}
|
[] |
[] |
[
[],
[],
[]
] |
|
4tx32f
|
[Astronomy] What kind of technology would a 65 million light-years away alien civilization need if they wanted to see the dinosaurs?
|
[deleted]
|
askscience
|
https://www.reddit.com/r/askscience/comments/4tx32f/astronomy_what_kind_of_technology_would_a_65/
|
{
"a_id": [
"d5kzu0j"
],
"score": [
6
],
"text": [
"The two big limiting factors are (a) resolution, and (b) brightness. For (b), you need a big collecting area and very sensitive detectors in your telescope. The particulars depend so much on technology that I won't speculate about what you need there.\n\nFor (a), we can get more specific, and talk about the Rayleigh Criterion. Because of the diffraction of light, there is an absolute minimum size for your telescope to be able to resolve small distant objects, regardless of technology.\n\nLet's assume you actually want to see dinosaurs, and not just indirectly detect their presence through their effects on the chemical composition of the atmosphere. To get enough resolution to have 10 cm resolution (enough to see a lot of detail on large dinosaurs, but not quite enough to resolve the smallest dinosaurs as more than a fuzzy blob) from a distance of 65 million light-years, in optical wavelengths, your telescope needs to be over 300 light-years across.\n\nI won't speculate about what sort of advanced technology these aliens might have, because that kind of guesswork isn't really science. So there's no sensible way to talk about how practical this would be for some hypothetical super-advanced aliens. But to properly see the dinosaurs, you would need an absolutely enormous telescope."
]
}
|
[] |
[] |
[
[]
] |
|
2zcrci
|
How would long-distance roads in 19th century America compare to modern-day highways?
|
Apart from main streets in towns, and separate from railroads used for long-distance travel, what would the experience be like traveling from, as an example, St. Louis to Kansas City with **horseback riding** and **covered wagons** being the main modes of transportation?
Were there designated roads, or just large areas of land for travelers to cross?
Were there service stations or any equivalent to modern-day gas stations?
Would it have been common to pass other travelers or have other interactions common on modern-day highways?
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/2zcrci/how_would_longdistance_roads_in_19th_century/
|
{
"a_id": [
"cphowz1",
"cphuvvx"
],
"score": [
5,
3
],
"text": [
"It would have been pretty terrible, frankly. Even in the 1920s and 1930s a long-distance journey in an automobile would have been anything but comfortable. There would have been designated roads, but before the 1920s, no standardized traffic signals. Very few service stations because there were so few automobiles to service. One reason why the Model T Ford really took off was the standardization in parts, making it much simpler to fix even in far off service stations. It would have been relatively common to see other travelers, especially after the 1910s. There start to open up National Parks, amenities aimed at tourists, and gradually - better roads. Many years earlier, like in the colonial era, for example, a traveler would have needed to exchange money every so often because there wasn't even a nationalized currency. This is all to say traveling long distances gets easier over time in the United States. \n\nIts sort of a myth that Eisenhower drew inspiration for the The Federal-Aid Highway Act of 1956 from his experience in Germany during and after WWII. In reality, Eisenhower was well aware this country had a problem with poor roads. When he was in the service before the war, Eisenhower was part of a terribly uncomfortable convoy going from PA to CA. He needed little convincing himself we needed new roadways and it helped further stimulate the economy. ",
"Long established Native American footpaths and trails across the landscape were also followed by the early trappers and settlers, and some of those evolved into wagon roads along popular desire lines. There was no need for service stations, but routes across the arid West were chosen for access to water and grass as well as easy grades and good footing. The coming of railroads meant there was little need for slow, difficult cross-country travel, and wagon roads fell into disuse in some areas, though short regional feeder roads arose to supplement the railroad network. As settlement expanded and farm- and ranchland replaced open prairie, the familiar gridiron of section-line roads was laid down *in theory,* though of course most of those remained unimproved until widespread auto ownership in the 20th century."
]
}
|
[] |
[] |
[
[],
[]
] |
|
2u6n07
|
what do presidents do after their term(s) is/are done?
|
Do they just chill around for the rest of their lives, or do they go back to regular work? If so, what work?
What if there was a really young president?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/2u6n07/eli5_what_do_presidents_do_after_their_terms/
|
{
"a_id": [
"co5lfho"
],
"score": [
2
],
"text": [
"They collect money for the rest of their lives from the government and the intelligent ones make even more giving speeches. "
]
}
|
[] |
[] |
[
[]
] |
|
12k5bv
|
Historical incidents of non-state-backed or subversive currencies?
|
I am wondering if there are historical occurrences or general trends of alternative currencies. And also how they affected the state in question, how commerce was done, the originators of the currency, enabling of black markets/underground economies, etc.
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/12k5bv/historical_incidents_of_nonstatebacked_or/
|
{
"a_id": [
"c6vqmon",
"c6vrgg3"
],
"score": [
2,
2
],
"text": [
"There's the [WIR Bank](_URL_1_) currency that's been in use since 1934 until now . . . does an alternative currency have to go into disuse for it to be historic? \n \nThe [The Wörgl experiment](_URL_0_) (July 1932 to November 1933) resulted in a growth in employment and meant that local government projects such as new houses, a reservoir, a ski jump and a bridge could all be completed, seeming to defy the depression in the rest of the country.\n\nYou've come here from /r/bitcoin - you really should ask there and in somewhere like /r/economics as well as here.",
"During the anarchy of King Stephen it's possible to chart the extent to which Stephen had control over the various parts of the country by looking at the different coinages issued. The reign was bookended by fairly stable, centrally issued coins but in the middle, particularly when he was captured, barons started just doing their own thing pretty much. Currency reform was a key priority of his successor, Henry II. They were as far as I know pretty much accepted by everyone, especially seeing as the majority of trade was local- coins were more given legitimacy by their weight (the exchequer would test coins by melting a certain number of pennies down and weighing the ensuing ingot against a pound).\n\nSource: the Reign of King Stephen- David Crouch (I think)"
]
}
|
[] |
[] |
[
[
"http://en.wikipedia.org/wiki/Local_currency#Historical_local_currencies",
"http://en.wikipedia.org/wiki/WIR_Bank"
],
[]
] |
|
7f2jhw
|
why is there a minimum age limit to vote but no maximum age limit?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/7f2jhw/eli5_why_is_there_a_minimum_age_limit_to_vote_but/
|
{
"a_id": [
"dq91q7z"
],
"score": [
2
],
"text": [
"Growing up is a more predictable process than ageing (even though it is not 100% predictable). Some 12 year old children are smarter than others, but they all have some degree of immaturity. Maturity takes time. Some elderly people remain quite smart even into their 90's, while other don't. Some people become senile as they age, and some don't. There is no way to set a maximum age for voting that is not going to disenfranchise a lot of very well qualified voters."
]
}
|
[] |
[] |
[
[]
] |
||
evkysu
|
why aren't there really big predators about the same size of possible prey? and sometimes there are big predators without big prey?
|
Disclaimer: read the edit at the end
I was wondering why there aren't predators about the same size of the biggest herbivors (or filter feeders) in a certain time.
For example, why isn't there some elephant size carnivorous species? Why the biggest sea predator (white shark, orca or sperm whale) doesn't reach the size of the blue whale? And even if it comes close to it (sperm whale) it isn't a direct predator of the blue whale itself. This goes also in prehistory where even the biggest theropods couldn't rival titanosaurs and sauropods.
The only exception i can see are prehistoric seas where basilosaurs, shonisaurs, mosasaurs etc.. (different ages ofc) where the biggest living creature (that we know) and also were predators. But even then they were predators of smaller prey, nothing really compared to their size.
**So in short why is it than in nature we either have bigger herbivours like beings (except blue whale that isn't herbivorous, but feels the niche i'm talking about).. let's call them preylike for the sake of this discussion, with no predators of the same size or we have big predators with no prey of the same size?**
With medium and small size there are many "matches" like wolves and deers, bears and seals, lions and zebras, allosaurus and stegosaurus, fox and rabbit and so on.. The only real exception i can think of is sperm whale and giant squid, but even then, blue whale is unmatched. Sorry if i used unappropriate terminology.
Thankyou
Edit: i do apreciate all the answers coming. And i had my question partially answered. This said i believe i expressed myself badly, so let me reformulate: why is it so that in any given point in time the biggest living creature was either a predator or a prey, but prey and predator of the same size never happened to live together? (if we are talking of maximum dimensions)
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/evkysu/eli5_why_arent_there_really_big_predators_about/
|
{
"a_id": [
"ffwazvz",
"ffx9f31"
],
"score": [
18,
2
],
"text": [
"I'm no biologist but from what I understand it's kind of just pointless. If you wanted to be large enough to eat a blue whale then you would need a ton of food to sustain yourself. Since you would need so much food the only really good meal for you is now whales. It's much more efficient to be smaller and just devour schools of fish instead. The same is true for land animals. It's much easier to be the size of a wolf and fill yourself up on 4 rabbits than it is to enlarge than a cow and need 30 rabbits to be full.\n\nTL:DR predators grow to the optimal size to consume their target prey as efficiently as possible.",
"In fact, all the largest animals in the ocean are predatory. I'm not exactly sure what the largest oceanic herbivore is, but my bet is that it's a manatee or dugog (RIP stellar's sea cow). Most aquatic predators prey on things substantially smaller than themselves (blue whales eat 2 inch long krill, for example, but even sharks usually eat smaller animals and killer whales usually eat smaller prey even if they do on occasion take larger whales). And as you note, the great filter-feeders of the modern ocean are a bit unusual. In the past the largest marine animals were mostly carnivorous.\n\nOn land the situation is a bit different, the largest herbivores are essentially always bigger than the largest predators. Even on land though, predators _usually_ prey on smaller or similar sized prey. Wolves take deer (as a pack, usually) but they often still focus on smaller fauns and eat a surprising amount of rodents and other small mammals. The really big mammals rarely suffer predator attacks. \n\nWhy? Well, it's complicated. Fundamentally, each step of the food chain you go up means there's less energy going around. Herbivores get about a tenth of the energy plants produce, carnivores get about a tenth of the energy herbivores eat, etc. An elephant-sized lion would need an _immense_ amount of herbivores to sustain itself. A whole population would need an immense amount of space (this is one reason things are bigger in the ocean...there's just more room and more food). Herbivores (and filter feeders) can get really huge compared to top predators in part because there's massively more food energy available to them because they eat lower on the food chain (note, even sperm whales _mostly_ eat much smaller squid that are much lower on the food chain than giant squid). Or to put it another way, think about how much food and territory an elephant needs. Now think about a predator the size of an elephant that eats an adult elephant every other day or so. How many elephants would it need each year? How much space would each of those elephants need? You begin to see the issue. \n\nSo why are there really big herbivores on land while most herbivores in the ocean are pretty tiny (most are actually miniscule copepods, even small-medium fish herbivores are fairly rare). On land, plants grow large and are filled with cellulose to support themselves. An efficient way to digest this is to carry around a big fermentation chamber in your belly, and the bigger it is the more efficient it is. So you get lots of big animals that carry around big guts to digest plants (note, though, that there are a ton of tiny herbivorous insects too, which eat a huge amount of plants). In the ocean, however, most \"plants\" are tiny single celled algae, and the most efficient way to eat them is to be an only-slightly-less tiny planktonic filter feeder"
]
}
|
[] |
[] |
[
[],
[]
] |
|
3dfyrp
|
How close was poland to giving Nazi germany the danzig corridor?
|
If at all
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/3dfyrp/how_close_was_poland_to_giving_nazi_germany_the/
|
{
"a_id": [
"ct4sg9v"
],
"score": [
7
],
"text": [
"This was the basis of my final paper during my undergrad, well it was more about the \"creation and effect on interwar German-Polish relations\" (to quote my title). And in short, not at all.\n\nFirst off it has to be noted that Poland never legally controlled Danzig. It was a Free City, nominally under control of the League of Nations but with economic ties to Poland. So even if the Poles wanted to give up the city (which they most certainly did not), they never owned it and thus couldn't.\n\nOne of the key demands of the Poles during the Paris Peace Conference was that they be given unimpeded access to the sea; they would not accept Germany to retain all the territory bordering the Baltic Sea, fearing that in the event of hostilities they would be barred from accessing it, and so wanted their own borders to reach the sea (and indeed an early German proposal of this calibre was rebuffed, with Lloyd George arguing that if the Germans felt it good enough for the Poles, it could work for the Germans).^1 This of course was opposed by the Germans, who would thus see East Prussia cut off from the rest of Germany, not to mention that the most logical choice, Danzig, was ethnically German (at the time 96% of the population identified as German).^2 In an attempt to rectify this, the Allies created a solution that \"satisfied none of those directly concerned^3: the Free City of Danzig. Though nominally a sovereign state, it was in a customs and economic union with Poland, who also controlled its foreign affairs and had unrestricted use of the port, as well as the ability to place a small military force within the city (at Westerplatte, where the first shots of the Second World War were fired).\n\nFearful that the status quo would not last, Poland began in 1924 to turn Gdynia, a fishing village a few kilometres from Danzig (but located entirely within Poland) into a viable alternative. Both Danzig and Germany argued this violated the treaty establishing the city, and thus it should have been allowed to return to Germany; this argument was denied by the League.\n\nThe rise of Hitler saw renewed efforts to bring the city back into German control. At one point he had even remarked to Józef Beck, the Polish foreign minister, that \"Danzig is German, will always be German, and will sooner or later become part of Germany.\"^4 However for various reasons it was not until 1938 that Hitler undertook serious efforts to reclaim Danzig. Various proposals were made to Poland, including extending the non-aggression pact signed in 1934, renouncing other territorial claims, and various other things; all were turned down (while the Poles didn't have control over the city, if they conceded to something the League would have signed off on it). Negotiations actually lasted until late August, 1939, but seeing how the Munich Agreement had turned out the Poles were less than interested in German proposals. Beck at one point even said to his German counterpart von Ribbentrop that \"any other solution, and in particular any attempt to incorporate the Free City into the Reich, must inevitably lead to conflict.\"^5\n\nFor some further reading on the city itself, there are some older books on the subject:\n\nChristopher M. Kimmich, *The Free City: Danzig and German Foreign Policy 1919 – 1934*. New Haven, Connecticut: Yale University Press, 1968.\n\nHerbert S. Levine, *Hitler’s Free City: A History of the Nazi Party in Danzig, 1925 – 39*. Chicago: University of Chicago Press, 1973.\n\nJohn Brown Mason, *The Danzig Dilemma: A Study in Peacemaking by Compromise*. Stanford, California: Stanford University Press, 1946.\n\nCasimir Smogorzewski, *Poland’s Access to the Sea*. London: George Allen & Unwin, 1934.\n\nThere are also some contemporary journal articles that look at the city; I haven't included them here, but can do so if requested. Other works on the subject of interwar Germany, Poland, the League of Nations, and so forth also often touch on Danzig, and look at the issue as well.\n\nNotes:\n1. Eyck, *History of the Weimar Republic, 107.\n2. H.L., \"The Problem of Danzig,\" *Bulletin of International News*, Vol. 13, No. 2 (July 18, 1936): 3.\n3. Levin, *Hitler's Free City*, 10.\n4. Shirer, *Rise and Fall of the Third Reich*, 457.\n5. Shirer, *Rise and Fall of the Third Reich*, 456"
]
}
|
[] |
[] |
[
[]
] |
|
wxgnq
|
What's the deal with the "thumbs up" gesture?
|
I have had several teachers/professors give conflicting explanations of how the "thumbs up" came to be a gesture of approval. Most have used the Roman gladiatorial games as the source, but almost none of them have agreed on how it was used. Did it mean a go ahead to let the opponent go? To kill him? Was it ever even pointing up? It's a pretty trivial topic, but any explanation will be appreciated.
Forgive me if this has been answered before.
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/wxgnq/whats_the_deal_with_the_thumbs_up_gesture/
|
{
"a_id": [
"c5hc1sn",
"c5hd3or",
"c5hdx2r"
],
"score": [
7,
2,
15
],
"text": [
"_URL_0_\n\nLooks to be as disputed as the origins of the word \"okay\" (Old Kinderhook?)",
"Does anyone know the history behind it being an obscene gesture? The Wiki states this is the case in some Middle Eastern countries and parts of West Africa, South America, Iran, and Sardinia. Is there a different gesture in these places that expresses the same positivity associated with the thumbs up?",
"It is now [commonly believed](_URL_0_) that \"thumbs up\" meant \"stab him in the heart\" - with the thumb representing the gladius, the short stabby sword used by Roman gladiators and soldiers. To this day, \"thumbs up\" is used [as an insult](_URL_1_) in Italian culture.\n\nIt's hypothesized that another symbol was to show the fist with the thumb exposed, and swing it horizontally, indicating a slicing motion - which meant \"slash his throat\". Another possible symbol was to show the fist with the thumb pointed down, which meant \"put your gladius down\". And, yet another possible symbol was to show the fist with the thumb hidden inside the fingers, which meant \"do not use the gladius\" - let the other gladiator live.\n\nRegardless of the many possible variations, it's now commonly believed that \"thumbs up\" probably meant \"death\" rather than \"life\".\n"
]
}
|
[] |
[] |
[
[
"http://en.wikipedia.org/wiki/Thumbs_signal"
],
[],
[
"http://www.unrv.com/culture/gladiator.php",
"http://www.explore-italian-culture.com/ancient-roman-colosseum.html#axzz21IJGBFaZ"
]
] |
|
4zs074
|
japanese fascination with hello kitty
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/4zs074/eli5_japanese_fascination_with_hello_kitty/
|
{
"a_id": [
"d6yda1d"
],
"score": [
15
],
"text": [
"Mickey Mouse is an iconic character in American pop culture for families. You grow up with him because you've been exposed to him all your life either through your parents or just having him shoved in your face through anything Disney. \n\nBasically Hello Kitty is the Mickey Mouse of Japan. "
]
}
|
[] |
[] |
[
[]
] |
||
4uvh75
|
the power of the potus. under what circumstances could a president give an order? what's to stop a president from giving an order to launch icbms at antarctica for no reason?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/4uvh75/eli5_the_power_of_the_potus_under_what/
|
{
"a_id": [
"d5t5d1o",
"d5t6ol7"
],
"score": [
4,
2
],
"text": [
"As far as ICBMs go, the contract you sign to enter the military stipulates that you are not required to follow unlawful orders, or orders that you believe shouldn't be followed (which of course is up to the interpretation of the courts when you get booted). If the president orders the nukes launched, it then has to go through military leadership to actually get to the people at the bunkers, and that leadership can refuse. Then it goes to the bunker commanders, who can refuse. Then it goes to the techs who actually \"press the button\", who can refuse. So the president can scream to launch the nukes until he's blue, but that won't necessarily lead to the nukes being launched. All of that is on purpose, by the way. No one ever thought one person should have absolute control over the nuclear arsenal. That's true even in Russia, where one commander more or less single handedly prevented the apocalypse by refusing to launch nukes when ordered to during the Cold War, because he suspected the incoming missile radar that went off was malfunctioning (it was).\n\nEdit: other comments are overestimating the president's authority and underestimating the willingness of people to disobey that authority. If the president ordered a nuclear strike on Antarctica he would have to have a damn good justification, the soldiers who man the silos aren't going to launch just because the president told them to. They know what's at stake. Sure, Antarctica isn't exactly teeming with life, but it would still violate a huge number of treaties and might lead to nuclear war just because by other counties reacting and launching retaliatory strikes before they know Antarctica is the target (and likely wouldn't believe us if we tried to tell them \"we're totally not shooting at you guys for real don't shoot back\"). Again, I want to emphasize that *this has already happened*. A launch was ordered, during the Cold War when there was way more tension and way more reason to believe a launch was necessary, and no missiles were launched.\n\nThe only way missiles would get launched is if there were already missiles in the air pointed at us, or a major invasion landing on US soil.",
"POTUS doesn't have the authority to start a war. Without an imminent threat the military would ask the president for the authorization from Congress for offensive actions.\n\nAdditionally there is a lot of leeway between executing an order and refusing an order. A nonsensical order like nuking Antarctica would involve multiple verifications at every level of command. This would cause significant delays for Congress or the cabinet to oppose the action.\n\nThink about it as if you are in the position of a middle manager in that communication chain. You would ask, repeatedly, if this was a joke or typo and ensure that what you think you're hearing is what was actually said.\n\nTechnical legal authority is a long way from actual ability to get something done. Example: every lieutenant that tried to order around a sergeant major."
]
}
|
[] |
[] |
[
[],
[]
] |
||
2alejx
|
if distilled water is just evaporated and then re-condensed, why isn't rain pure water?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/2alejx/eli5_if_distilled_water_is_just_evaporated_and/
|
{
"a_id": [
"ciwaud3",
"ciwaw1b",
"ciwf3ys"
],
"score": [
9,
2,
2
],
"text": [
"Because distilled water is theoretically distilled in a controlled environment. There is dust and pollen and smoke and shit in the air and clouds which contaminate rain. ",
"Because there's stuff other than water in the clouds, some air bourne bacteria can float around in clouds and there is a lot of dust up there too. Basically if it can float in the air it can get into rainwater but mostly it's safe to drink but there are far fewer beneficial chemicals like fluorides in rainwater so you'd be better off drinking tap water.",
"Simply, have you heard of acid rain? Gasses and dust and smoke in the air rinse into the earth by being a part of each drop of rain or flake of snow. "
]
}
|
[] |
[] |
[
[],
[],
[]
] |
||
fklt3h
|
how does inhaled asthma medications weaken your immune system?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/fklt3h/elif_how_does_inhaled_asthma_medications_weaken/
|
{
"a_id": [
"fktfke5"
],
"score": [
12
],
"text": [
"asthma medications are generally a sympathetic stimulant and a corticosteroid. \n\nThe sympathetic stimulant does the same thing that your body does during fight-or-flight. Both cause your lungs to \"open up\" so you can take in air better because asthma causes your lungs to 'close up'\n\nCorticosteroids are immunosuppresants because asthma is an inflammatory condition (which is driven by the immune sysem) and triggered by allergens. Immunosuppressants tone town the response to these allergens and reduces the inflammation in asthma.\n\nSome of those immunosuppresants will make it into your blood, even though it only need to act at the lungs. And it can affect your immune system throughout your whole body due to it."
]
}
|
[] |
[] |
[
[]
] |
||
f6g1zc
|
Did the Japanese ever resort to using biological and chemical warfare against the Americans during the Pacific War?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/f6g1zc/did_the_japanese_ever_resort_to_using_biological/
|
{
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"text": [
"They never brought out the chemical weapons, no. I touch on this a bit in [this longer answer](_URL_0_), but to reiterate, where there were a few scattered reports of individual grenades being used, these almost certainly were isolated incidents at best, and not a reflection of Japanese policy in the fight with the USA."
]
}
|
[] |
[] |
[
[
"https://www.reddit.com/r/AskHistorians/comments/bqdimf/this_maybe_silly_but_after_signing_the_geneva/eo54p8e/"
]
] |
||
3og0b6
|
why is is customary in rap/hip-hop to use a different name?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/3og0b6/eli5_why_is_is_customary_in_raphiphop_to_use_a/
|
{
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"cvwul54",
"cvwww8y"
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"score": [
3,
2
],
"text": [
"It's often a part of culture. Especially in the African American community, nicknames are what people are most known by. ",
"Its just a convention of hip hop. \n\nProbably influenced by very early NY hiphop being closely linked with graffitti, where you'd make up a tag, coz writing your government name on the side of a train isn't smart. The common hiphop thing of using lots of numbers and letters was also big in early NY tags (eg T-kid, futura 2000)\n\nSome other music genres have similar conventions. In punk bands its also common to give yourself a silly name (eg Poly Styrene, Rat Scabies, Chuck Wagon, etc). Bluesmen had nicknames too (Howlin Wolf, Muddy waters, Blind Lemon Jefferson)\n\nSome stuff just becomes \"how it is\" in genre. "
]
}
|
[] |
[] |
[
[],
[]
] |
||
b3g84n
|
is there any scientific basis for horoscopes?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/b3g84n/eli5_is_there_any_scientific_basis_for_horoscopes/
|
{
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"text": [
"Only in the sense that there are constellations in the sky. Those exist, although they're more folklore than science.\n\nThe actual horoscopes themselves are not based in science.",
"The horoscopes are based on constellations (star patterns) that were recorded over 2000 years ago.\n\nSince then the earth has shifted, making all current horoscopes based on those recordings incorrect by over 1 month.\n\nSo even if horoscopes were real (which they're not), then you wouldn't be the sign you think you are anyway. ",
"What other people said, with the only addition that as it corresponds to a birth month, there's the POTENTIAL for shared environmental factors as a result of birth month. In a modern society where our diets are fairly standard year-round it's less prevalent, however it's possible that in the past things such as the availability of fresh fruits and vegetables only during certain times of the year may have had unknown impacts on children based on prenatal nutrition. In the modern day United States, most states have grade cutoffs for kindergarten based on being age 5 in either august, September, or October, so children born in November may be 11 months older than some of their peers, which may have various developmental side effects related to a child's education and social environment.\n\nThat being said, that's less to say that any of this would have any of the specific attributes associated with various birth signs. I was mostly pointing out the actual ways in which different signs/birth months MAY alter a person and MAY provide for some POSSIBLY statistically significant differences between those born in different months.\n\nEdit: Typo"
]
}
|
[] |
[] |
[
[],
[],
[]
] |
||
v7nia
|
Why does uncooked pasta take a long time to expire?
|
I had some uncooked pasta laying around and cooked it today. Why does uncooked pasta take such a long time to expire compared to, say, milk or bread?
|
askscience
|
http://www.reddit.com/r/askscience/comments/v7nia/why_does_uncooked_pasta_take_a_long_time_to_expire/
|
{
"a_id": [
"c521k0b",
"c522foo"
],
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8,
3
],
"text": [
"It is dried, nothing to go stale and nothing for any microorganisms to live in.",
"Anything dehydrated has a long shelf life.\n\nSee: Rice, Beans, Crackers or Croutons (to a degree, they arent quite dehydrated bread, but close.), beef jerky, and dried fruits like bannana chips are all great examples of similar situations."
]
}
|
[] |
[] |
[
[],
[]
] |
|
2wqrc2
|
why do some cigarette smokers end up with huge health complications (artificial larynx, tracheotomy, etc.) while other heavy smokers seem to have been smoking for years with minimal complications?
|
I fell like this is gonna get down voted to hell, but I'm honestly curious as to why some people die from lung cancer, or end up having to have tracheotomies due to heavy smoking, (like in those anti smoking commercials where all those people talk about how hard it is living with a stoma in their neck) but other heavy smokers (that smoke multiple packs a day) seem to just have a raspy voice or an occasional heavy cough. Is it just sheer luck as to who gets horrible side effects and who doesn't? Or were the people with artificial larynx just smoking a lot more cigarettes, over a much longer period of time? Any information would be appreciated. Thanks!
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/2wqrc2/eli5_why_do_some_cigarette_smokers_end_up_with/
|
{
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"cot9mqk",
"cotaoz5",
"cotby3o",
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"score": [
12,
36,
3,
2
],
"text": [
"Two possibilities:\n\n1) There is just a random \"chance factor\" involved\n\n2) There are one or more factors that we have not yet discovered or do not yet fully understand\n\n-------------------\n\nI have had about 40 cats in my lifetime. None of them smoked, drank alcohol, or ate anything other than a veterinarian approved diet. Still, 3 of them died of cancer.\n\nWhy? I don't know.\n\n-------------------\n\nGeorge Burns drank and smoked for most of his life...\n\nWhen asked, after he was 90 Years Old, what his Doctor thought about his Smoking and Drinking, he replied...\n\n\"My Doctor is Dead.\"\n\n-----------------\n\nHowever, it does increase your RISK of certain diseases and conditions if you engage in certain activities.",
"Statistics. Smoking does not guarantee health complications, it only increases your risk of them.\n\nWho ends up with health complications is a matter of environmental factors and genetics. A light smoker might end up with lung cancer while a heavy smoker has only a light cough. But make no mistake - on a global level, the heavy smoker is, on average, much worse off than the light smoker. But there will always be exceptions.\n\nBut we don't know all that much about how genetics and environmental factors affect this. So to modern healthcare, it basically is luck that determines who ends up with complications and who doesn't. With statistics though, we can see that smokers are on average worse off than those who don't smoke, and heavy smokers versus light smokers.\n\nYou should also be aware of perception biases - the heavy smoker who stays healthy is a surprise, so you're going to hear stories about them - it's newsworthy and interesting, and you're more likely to remember that tidbit of information. But you don't hear about the 100 other smokers that died of lung cancer, because that isn't news, it's what's expected, and you're also less likely to remember that information because it isn't that interesting.",
"One point that is not well understood...\n\nI learned this when my Grandfather was dying of Lung Cancer...\n\nLung Cancer is a HUGE BIG DEAL in the \"Cancer World.\" Lung Cancer blasts Breast Cancer and Colon Cancer out of the water, when it comes to the amount of lives claimed.\n\nOne doctor has even made a famous quote... When asked, \"Who is at Risk of Lung Cancer?\" The doctor replied, \"Anyone with Lungs!\"\n\nWhile smoking does greatly increase your risk of developing Lung Cancer... LOTS of people who DO NOT smoke die every year from Lung Cancer.\n\n",
"My grandpa, god bless his soul, smoked up until his death. He lived to be 96, and to \"combat\" the smoking issue, he would drink a tiny cup of olive oil a day. I don't know why, but he though that would make him live longer, seems like it worked. "
]
}
|
[] |
[] |
[
[],
[],
[],
[]
] |
|
19nmif
|
Wouldn't implanting young DNA compatible cells that replicate normally without being targeted by your immune system be the "cure" for old age?
|
askscience
|
http://www.reddit.com/r/askscience/comments/19nmif/wouldnt_implanting_young_dna_compatible_cells/
|
{
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"c8pnw0x",
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"text": [
"This may be true if all cells in your body continually divide, but there are important cells (such as almost all your neurons in your nervous system) that are post-mitotic and will accumulate DNA damage over time.",
"As many have stated (and you seem to have rejected), not all cells in your body are constantly undergoing replication. Aging is a complicated process; simply injecting/implanting stem cells into your body isn't going to stop aging. For one, as you age (hell, as you gestate), your body follows a programmed development process where your organs form and your body takes shape. Without these developmental programming and signals (which we don't fully understand yet) to tell your stem cells how to develop, they won't just magically replace your existing cells and make you young again. Best case, they just do nothing; worst case you just gave yourself cancer."
]
}
|
[] |
[] |
[
[],
[]
] |
||
2p2j8u
|
why do indians bobble their heads when speaking? (no racism intended
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/2p2j8u/eli5why_do_indians_bobble_their_heads_when/
|
{
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"text": [
"It's simply a gesture that's become culturally common in India.\n\nHere's a [video which explains the meanings](_URL_0_).",
"They don't bobble there head when speaking, they bobble their head as a sign of agreeing or saying yes to something. More common with South Indians. ",
"Sometimes it's used to denote the feeling of \"yes, but no.\" ",
"Indian here, I didn't even realize the head bobble was unique to us till it was emphasized on Outsourced. \n\n\nI've always thought it was for signifying uncertainty ( at least that's what I use it for) . Like when my manager wants me to do something but doesn't explain the specifics, that's when I do the head bobble and accompanying that I'll say \" Ok, sir.\" and inside I'm just thinking that yeah this is going to be a little tough and irksome to figure out, but I can do it.\n\nMy take is that the bobble is rooted in the fact that as a society we're quite non-confrontational, respect hierarchy ( office, familial or otherwise) and we're taught to respect people older to us ( Indians take respecting elders very very seriously). So the bobble is a polite way to let the other person know, that you're not too sure about what's going on.\n\n\nSo next time an Indian bobbles his head and says he agrees with you, you'll know better.",
"Also Indian here. I've heard the respectful, non-confrontational reasoning before, not sure how much I buy that. That may have been the origin of these gestures. Doesn't apply as much now, but you learn what you see.\n\nYou may have also observed that Indians gesticulate (with their arms) a lot less than Caucasians do. I guess body gestures are fundamental to communication and if you don't do them one way, you do them another. Although head-bobbing is mostly on the part of the listener in a conversation, rather than the talker.\n\nAs an aside, there's by no means a universal head-bobbing language within India. The same bob may mean exact opposite things depending on where in India you're from.",
"It took me a while to understand that the team from Bangalore I was working with would shake their head (as if to say no) when they were agreeing with me and nod when saying no. A bit strange at first but not a problem once we all understood what was going on (they had been confused by my head gestures as well). "
]
}
|
[] |
[] |
[
[
"https://www.youtube.com/watch?v=Uj56IPJOqWE"
],
[],
[],
[],
[],
[]
] |
||
ftu9n3
|
what is the difference between insurance and a provider?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/ftu9n3/eli5_what_is_the_difference_between_insurance_and/
|
{
"a_id": [
"fm94kir"
],
"score": [
3
],
"text": [
"Medi-Cal is a state of California program to insure people who need insurance. There are many Medi-Cal providers, and it seems you got assigned to Molina. So, Molina is your insurance company. This is not the same as a medical provider. You'll need a Doctor to treat you, and you'll need one that accepts payments from Molina. That's probably listed on the Molina website someplace, as insurance companies are all about making sure that you go to medical providers that they have fixed-price contracts with."
]
}
|
[] |
[] |
[
[]
] |
||
rbqyc
|
how do snakes and other poisonous animals/insects produce their venom?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/rbqyc/eli5_how_do_snakes_and_other_poisonous/
|
{
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"c44j2aq",
"c44ra2k"
],
"score": [
6,
2
],
"text": [
"Snakes have [special venom glands in their heads](_URL_0_). Spiders may just use digestive juices.",
"Some animals, such as nudibranchs, consume poisonous prey and, rather than breaking down or being affected by the poison, store it in their bodies to become poisonous themselves. "
]
}
|
[] |
[] |
[
[
"http://reptilis.net/serpentes/venom.html"
],
[]
] |
||
4slrft
|
what exactly is google's tensorflow?
|
I recently came across TensorFlow, which from what I've read seems to be a pretty big deal in the A.I. community. But as a person with no computer science background, nor any real knowledge in AI, I still don't understand it!! What even is it? and what is it used for?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/4slrft/eli5_what_exactly_is_googles_tensorflow/
|
{
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"text": [
"After dooing some quick research (2 google searches). The new google Tenserflow is a deep learning ai. You can use the code to set up ais like the AI created by google to detect cat photos. This is a step up from their old ai system because this code is twice as fast and also really smart.\n\nNot only that but its open source!\n\nEven though all the advancements are cool and all. If your wondering why this is super important. Tenser flow is the same software running in many of your products today. So knowing that it will get smarter and faster is a step up.\n\n\nI just looked at the date. Tenserflow was released a year ago. So I did some more digging. recently Tenserflow has gotten supercharged with more efficient code, and the ability to work on multiple machines. Before Tenserflow can only be ran on one computer at a time. That was pretty deficient before, but now it's faster.\n\nAll in all. Tenserflow is a newer faster system that is way better than what some companies have now. And not only that, but the technology can be used by anyone, free of charge\n\nI have to Goto bed, hope this helped.\n\nEdit: a few words",
"If you have no compsci background, we need some introduction. When a developer is writing software, they are _rarely_ thinking about explicitly pushing around 0's and 1's around on a some chip. That's because pushing around 0's and 1's is usually boring and needs to happen a few billions times per second. There are layers and layers of programs between a software developer and the binary shit that makes a computer go at the circuit level (usually). This is called 'abstraction', or 'making stuff easier to think about'. When programmers write an application, they often use collections of code called 'libraries' that make complicated shit easier to avoid reinventing the wheel. TensorFlow is an open-source library that makes machine-learning shit easier to program. Open source means Google posted the code that makes it go on the internet where anyone can read it (and spot flaws). It's important primarily because _Google_ released it. What that means is that people expect Google to _maintain and improve_ TensorFlow. Most people do not have the time or resources to make a large and quality software library, as well as fix all the shit wrong with it that users find. Google has resources and people with huge expertise in lots of necessary fields (machine learning, AI, software development). That means people who start projects can leverage the expertise of the folks at Google, and trust that the library will be supported (patched, improved, extended) for some time to come.",
"It's a library. Think of it as a pre-made tool for working on something (in this case AI). Just like when you want to repair something you don't start by creating your own screwdrivers, hammers, etc. You use the ones available. (Tenserflow represents the tools in this example).\n\nAs for AI. It's just a subset of CS that uses graphs, statistics and probability to get some results. It \"learns\" by getting examples of right results. (Let's say you want computer to \"learn\" to predict which team wins a certain match. You start by giving it previous matches, info about them and the result - > who won. After giving it info about any match it will be able to predict who won based on what it \"learned\" from your examples).\n\nSome exaples of where AI is used are: self driving cars, recommendations, figuring out what is on image, voice recognition, translation, autocomplete keyboards, playing games, coloring colorless images, spam filtering...\n\n"
]
}
|
[] |
[] |
[
[],
[],
[]
] |
|
15yzq8
|
how is adblock plus able to remove the ads that stream before youtube videos?
|
Also I believe it removes ads that are overlayed on top of the video. How does it do that? How hard would it be for youtube to detect and prevent this?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/15yzq8/how_is_adblock_plus_able_to_remove_the_ads_that/
|
{
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"text": [
" > How does it do that? How hard would it be for youtube to detect and prevent this?\n\nAdblock programs work by reading the instructions to build the webpage, and telling the browser not to follow certain ones.\n\nTo prevent that, YouTube would need to make the ads indistinguishable from other content, to the browser.",
"All ads are shown in pretty much the same way, they send a request out to a server and the server sends back the ad. Adblock is just a list of servers it refuses content from if seen. Sometimes the Adblock will try and find the block on the page that the ad *should* have been shown in and remove that too, so you don't even see a blank space.\n\nThey can't really prevent it. Everything has to come from a specific place and be shown in a specific place. Find either of those and you can get rid of it.",
"So how does the fan boy list and other lists work? "
]
}
|
[] |
[] |
[
[],
[],
[]
] |
|
1mkhb7
|
why is there no color on magnified images. (i.e. images of bacteria)
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1mkhb7/eli5_why_is_there_no_color_on_magnified_images_ie/
|
{
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"cca2a1o",
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3
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"text": [
"It all depends on which type of method you use for magnification. If you use an ordinary optical microscope you will actually see colors. Optical microscopes are however limited in how small things they are able to see. Therefore different kinds of electron microscopes are used to see smaller things. Because \"color\" is a property of light it will not be visible in an electron microscope. ",
"I'm a microscopist! I do a combination of transmission electron microscopy, scanning electron microscopy, and focused-ion beam work. The specifics of each instrument don't matter, but I wanted to give you a quick idea on the scope (hehe) of my work.\n\nThe reason your images are black and white is probably because they were taken in an electron microscope! Electrons can behave as both a particle and a wave. When we consider their wave-like nature, they can have a super tiny wavelength on the order of single nanometers, which is 10^-6 millimeters! That's a great deal smaller than light, which is hundreds of nanometers! This means that our electron scope's resolution, which is the minimum distance between two points that makes it so we can see TWO points and not just one blob, is waaaay smaller!\n\nElectron images are black and white because we are looking at *contrast*. If we shoot a beam of electrons at a bacteria, some of the electrons are absorbed and others can do all sorts of fancy things like scatter, reflect... it's actually a really long list! Furthermore, the specimen also emits signals like x-rays and additional electrons due to interaction with our electron beam. When we pick up on these different things with a detector, it gives us a signal! If we're getting a picture, this signal can be bright or dark from different places, giving us the contrast that you see.\n\nColor can be LATER introduced into the image based on artistic ideas or if we know information on the composition or structure of the sample and want to communicate it clearly. This *false, often arbitrary color* can be really misleading to the untrained eye, but very useful and pretty for magazines or quickly conveying information!\nI hope that was sufficiently ELI5... I'll be back on later if you want to ama! \n\nTL;DR Electron microscopes give contrast, not color! "
]
}
|
[] |
[] |
[
[],
[]
] |
||
1jien5
|
is being vegetarian healthy and is it feasible at the population level?
|
I've heard conflicting views on the healthiness of being vegetarian. As an individual, does it have the potential to be healthier than eating meat or will there always be deficiencies?
Also is it possible for the whole population to live without meat or would this negatively affect the ecosystem somehow?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1jien5/eli5is_being_vegetarian_healthy_and_is_it/
|
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"text": [
"1) Vegetarianism is healthy but you usually have to be a little more aware of your diet. People need things like protein and iron which are extremely prevalent in meat but can substitute different fruits/vegetables or even vitamins to make sure they get what their bodies need.\n\n2) This is more theoretical/difficult to say but it's likely possible as we could eliminate livestock populations, freeing up much more food for human consumption. It's unlikely to ever happen but if it did it may be better for our environment as fruits and vegetables usually don't require as much energy to produce as meat (imagine how much corn you need feed a cow for 1 lb of edible beef compared to just eating 1 lb of the corn instead). The fertilizer run-off/water balance could present issues though.",
"There is no doubt that replacing meat with vegies would be better for the environment. It takes a hella lot more energy to produce beef rather than, say soybeans or peanuts. Less farm animals means less carbon dioxide and methane in the air that would boost global warming. Another problem with livestock is that grazing destroys the soil leading to desertification which is a big fancy word for creating deserts or land that is infertile. \n As for healthier for humans, it depends. Since livestock (generally cattle) is fed antibiotics to kill off bacteria which would stunt growth, bacteria that are immune to the antibiotics evolve, which can wreak havoc if it reaches people. Many meats also contain fats which are bad for people as well. This is all well and good; however, what people replace this stuff with can be just as bad. Many packaged foods also contain harmful ingredients and we would no doubt eat more of those if we couldn't eat meat. Being vegetarian also means making sure we still somehow get the protein we need which, while not impossible, may be hard for some people. \n I have seen some vegetarians pull it off well and others who clearly didn't plan it through. Maybe I'm missing some things, but that is the just of it.",
"Being vegetarian *can* be healthy if you pay attention to what you eat & have a balanced diet. If you just suddenly stop eating meat and think things will work, you're going to have problems. There are religions and societies (large groups of Hindus, Sikhs, Buddhists and Seventh Day Adventists have been doing it for a long time) that do it so it can work for large populations."
]
}
|
[] |
[] |
[
[],
[],
[]
] |
|
11979s
|
If we were to start using solar power on a large scale, would we be able to slow climate change on the back end as well as the front? (Explanation inside)
|
This is probably a dumb thought, but bear with me.
If we were to start using solar power on a very large scale, we would certainly be able to slow climate change by reducing CO2 emissions. This is the obvious benefit. But I was thinking, would we be able to slow the heating of the plant by collecting the sun's heat energy and converting it to usable electricity? For instance, the sea ice melts and the reflective properties that are lost as a result causes warming of the oceans. If we were collecting energy in solar panels, could there be a meaningful amount of heat absorbed through that process that would have otherwise baked the earth resulting in rising temps?
I feel dumb asking this and I am articulating poorly, but I am hoping someone can help decipher this notion of mine.
|
askscience
|
http://www.reddit.com/r/askscience/comments/11979s/if_we_were_to_start_using_solar_power_on_a_large/
|
{
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"c6kf6mp"
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"text": [
"Let's examine this from a few perspectives with a few totally unreasonable assumptions:\n\n*The power storage capacity it present in a perfect state and can act as a load follower\n* All power used throughout the whole world is provided via Solar power (this includes transportation like cars)\n*The replacement of infrastructure produces a neutral net change in CO2 emissions.\n\n1) How much power are we replacing and how many solar panels do we need?\n\nAccording to [this wiki article](_URL_1_), the total energy consumption of the world is 16,819 TWh. We'll round this out to 20k TWh (TerraWatt-Hours) to ensure that we have a bit of a surplus. \n\nWe'll take the Agua Caliente Solar Project as an example of current technology, since it was commissioned in 2011 and is the largest project I found. It produces an annual generation of 626 GW-h. This means we would need approximately *32 thousand Aqua Caliente Solar Projects to supply the world it's energy needs.* This equiates to 76.8 Million acres of land or 120k square miles (311k sq km). This is an area larger than the state of Nevada. \n\n2) How much energy is reflected back?\nAccording to [this article](_URL_0_), the earth receives 174 Pettawatts of solar radiation. Only about 70% hits earth. It doesn't have any information about how much is absorbed by clouds, so let's just use the 70% figure for estimation purposes.\n\nLet's assume the total amount of light hitting these panels is reflected back at 100% efficiency. The solar site in the example above had a capacity of 247MW. Let's also assume that this takes into account a conversion rate of 20%. This means that the total solar site receives 1.25GW of power. This equals about 40 terawatts of Solar Radiation (I think this number seems a bit high but let's assume it's correct). This is equal to .03% of the energy hitting the earths surface. I don't think this amount of reflection would cause any kind of noticeable effect.\n\ntl;dr: Solar station the size of Nevada could power the world with no affect on absorbed light."
]
}
|
[] |
[] |
[
[
"http://en.wikipedia.org/wiki/Solar_energy",
"http://en.wikipedia.org/wiki/World_energy_consumption"
]
] |
|
14btfr
|
why some condiments are labeled as fancy
|
For example ketchup sometimes has the word "fancy" on it. Also, my packet of jam has "Grade A Fancy" in very small print written on it.
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/14btfr/eli5_why_some_condiments_are_labeled_as_fancy/
|
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"text": [
"It is used mainly as a marketing term and as a designation of quality\n\n\n\"According to Heinz, “fancy” is simply a USDA designation that producers are allowed to use for marketing if their product meets the standards of US Grade A/US Fancy tomato ketchup, which possesses a better color, consistency and flavor, and has fewer specks and particles and less separation of the liquid/solid contents than US Grade B/US Extra Standard Ketchup and US Grade C/US Standard Ketchup.\"\n\n\nSource: _URL_0_"
]
}
|
[] |
[] |
[
[
"http://www.mentalfloss.com/blogs/archives/107311"
]
] |
|
f4kxmb
|
Could American Civil war be avoided?
|
Could American Civil war be avoided if the North abolitionist ideas weren't so aggressive and the South more willing to compromise?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/f4kxmb/could_american_civil_war_be_avoided/
|
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"There's always more that can be said, but you might enjoy these older threads that touch on similar areas. \n\n/u/sowser and others essentially discuss much of your question in [Tell me if this is crazy. Could the American Civil War have been avoided by Lincoln PAYING monetary compensation to the South in exchange for no more slavery?](_URL_0_)\n\nand /u/Georgy_K_Zhukov did [Why was there a Civil War? Why could that one not have been worked out?](_URL_1_)",
"Well, it's certainly *possible* that had historical actors made different choices, historical events may have unfolded differently. History, after all, is never inevitable. But I think it's worth breaking down the possibilities that you put forward to explain why they would have been unlikely.\n\nFirstly, abolitionist intensity: today many of us with some familiarity with 19th century history remember some famous abolitionists with a great deal of admiration. Men like Frederick Douglass and William Lloyd Garrison. Women like Harriet Tubman and Harriet Jacobs. They're famed and admired for good reason! All of them courageously advocated the cause of human freedom, at serious risk to themselves (Douglass, Tubman, and Jacobs had all emancipated themselves from slavery, risking torture and death in the process and risking recapture by publicizing their experiences, even the freeborn white Garrison faced the threat of vigilante terrorism). They were also completely unsparing in their condemnation of slavery and slaveholders. Garrison, whose politics may have been the least practical and most radical of the famous abolitionists, was advocating secession long before the South ever went through with it, only he felt that the *North* should secede from an inherently illegitimate constitution that shamefully protected slavery.\n\nStrident and radical as the critiques of such abolitionists were, they represented the views of a minority of abolitionist activists, who themselves represented only a minority of the Northern population. Most abolitionists, at least before 1860 or so, favored gradual emancipation with compensation for slaveholders (bear this in mind when I discuss southern intransigence later). They also had little interest in black civil rights or racial equality, with most (even *Lincoln* until 1862!) favoring the \"colonization\" of emancipated black people in Sierra Leone or Liberia (several thousand free black Americans actually did emigrate to Liberia in the antebellum period, but that's a story for a different post). Most white northerners were quite racist and saw little reason to sympathize with the plight of the millions of enslaved workers in the South. Many urban northerners were actively hostile to emancipation both out of racism and a fear of competition from free black labor (based on the logic that they would, once emancipated, flood northern cities and take jobs from white laborers by being willing to work for lower pay).\n\nYou might wonder, why would the South be worried about Northern antislavery if the radical abolitionists were such a small part of Northern opinion? Well, by the 1850s, antislavery sentiment was pretty widespread in the North for reasons independent of anti-racism or moral objections to enslaving black people. Northerners feared \"the slave power.\"\n\nSince the ratification of the constitution (arguable since the colonial era), slaveholders held a disproportionate amount of power in the operation of the American federal government. The three-fifths compromise granted them disproportionate representation in the House of Representatives. 10 of the first 16 presidents were slaveholders, and there were slaveholding southerners in most presidential cabinets (I'm tempted to say \"all,\" but am not a hundred percent confident that's the case). The first few decades of American nationhood saw north and south exist in a very fragile compromise, with policies like the Missouri Compromise (for every slave state added to the expanded nation, a free state added as well, and vice versa) designed to keep a balance of power between the free and slave states. But I'd argue, and so would many nineteenth century northerners, that the south had a decided advantage in the national power realm through most of the antebellum period.\n\nMost white Northerners were proud to live in a democratic republic, and while they might not have cared about enslaved people as people, they understood slavery as a threat to democracy in the abstract. At the very least, it had to be contained, lest aristocratic slaveholders spread throughout the entire nation, replacing the small farms where a majority of white Americans lived and worked with massive slave labor plantations. From their miniature fiefdoms, it was feared, the \"slave power\" would be in full control of national policy, free to govern to their own advantage and the disadvantage of decent free working white people everywhere. Whatever the ultimate fate of slavery, its expansion had to be regulated and contained.\n\nWhich brings us to the slaveholder perspective on things. Slaveholders did not secede merely because they were offended by abolitionist rhetoric. Though they were so offended by abolitionist rhetoric that they often responded to it with brutal violence.\n\nThe Proslavery American Dream depended on the ready availability of land. A slaveholder bought land, then received credit based on the value of the land, which they used to purchase enslaved workers to grow cotton (enslaved workers produced a lot of different kinds of commodities, but cotton was the main driver of this expansion), having sold the cotton and made a profit, they could buy more land. Rinse and repeat from generation to generation and you have the proslavery vision of the future. For most of the antebellum period, land was easy to come by -- Indian removal under Jackson opened millions of acres of some of the richest soil on earth in the Southeast, the war of conquest the United States waged against Mexico gave the United States political control stretching across the continent -- but as time went on, particularly after the Mexican American war, the Northern desire to regulate slavery's growth and the southern desire to expand slavery indefinitely clashed with more intensity than they had before.\n\nYou can see how a vision of the future like that held by slaveholders would have little room for compromise. How could it? Without more land, how were younger sons supposed to support themselves and establish their own plantations? Without “diffusing” the enslaved population by spreading them out across a wider geographic area, how could they stave off the ever-present threat of apocalyptic rebellion? Never mind the fact that that last point doesn’t really make sense if you think about it, since the enslaved population would grow as it spread if trends continued.This, of course, barely touches on numerous other reasons why southerners refused to countenance a future without slavery in general: racist paranoia about a society full of free black people, fear of economic ruin, attachment to the power and prestige that slaveholding bestowed, etc. Given the mental universe that American slaveholders occupied, it's hard to see how they could rationally have been less intransigent, given that they were unwilling to see slavery end. So when Abraham Lincoln won the election of 1860 on a platform promising not to end slavery but simply to halt its expansion, they knew an existential threat when they saw one."
]
}
|
[] |
[] |
[
[
"https://www.reddit.com/r/AskHistorians/comments/42y9jk/tell_me_if_this_is_crazy_could_the_american_civil/",
"https://www.reddit.com/r/AskHistorians/comments/68myvr/why_was_there_a_civil_war_why_could_that_one_not/dgztopa/"
],
[]
] |
|
9qyivz
|
why is the sun so bright and hard to look at when at noon but becomes dim enough at dusk that we can clearly make out its perfect circular shape
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/9qyivz/eli5why_is_the_sun_so_bright_and_hard_to_look_at/
|
{
"a_id": [
"e8cocqx"
],
"score": [
7
],
"text": [
"The distance the light travels through the atmosphere. When it's directly over you it doesn't have to travel a long distance, but when it's close at the horizon it has a lot of atmosphere to travel through which dims the light and the refraction of particles in the atmosphere also cause the sky to light up in different colors during that. "
]
}
|
[] |
[] |
[
[]
] |
||
bfu7du
|
why do banks use apple/google pay for contactless payments instead of their own apps?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/bfu7du/eli5_why_do_banks_use_applegoogle_pay_for/
|
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"text": [
"In short, why spend a lot to compete against the leading players in the market to offer the same service when you can just join them.",
"Because much more people use google or Apple Pay instead of the banking organisations one allowing the aforementioned to be much more polished and user friendly",
"The big money here is in the card transaction fees, not in what Google and Apple get. Particularly in the US, those card fees are high and they go to the banks, credit card companies and the processing companies. Because each bank would need its own app, it’s easier and cheaper for them to get Apple and Google to handle that part while they make the big money with the card fees. \n\nAnd before the credit card shills land on my comment with their disinformation bullshit (they always do), Stripe charges 2.9% in the US and 1.4% in Europe. There is both competition and pricing regulation in Europe with credit cards, both of which are essentially nonexistent in the US.",
"Liability.\nIf their App has a catastrophic security bug, and you money gets pulled out of your phone by someone via an NFC vulnerability. They are 100% liable (even though they will blame the user, especially in the case of a Debit Card).\nIf there is a bug in ApplePay or GooglePay, the liability would be spread between the bank, Card Vendor and Apple/Google.\n\nWhen Australian banks didn’t want to sign up to ApplePay, they (and Visa/MasterCard) started pushing NFC bracelets to compete with AppleWatch and Amex. The problem was that there was no Authentication so someone could walk past one of these bracelets with a Square reader and pull out some money.There were a lot of fraudulent transactions before they recalled them.",
"The built-in system apps are a better user experience. On Apple devices, Apple Pay is the *only* way to do it, but there’s still a compelling reason to choose Google Pay too. I’ve got cards from half a dozen different banks and I actively switch between them to pick the right one I want for any transaction. This is super easy with Apple Pay. If some bank’s cards were siloed off in their own app, but others were available in Apple Pay, guess which ones will be used more? Banks desperately want to be your default card in Apple Pay or Google Pay."
]
}
|
[] |
[] |
[
[],
[],
[],
[],
[]
] |
||
8xzmey
|
Did Roman people ever travel by aqueduct?
|
I feel almost silly asking, but even if not an official mode of transportation someone must have ridden an aqueduct as a shortcut. I was thinking of the importance of canals and the idea popped in my head.
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/8xzmey/did_roman_people_ever_travel_by_aqueduct/
|
{
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"text": [
"related- was there any policing of the aqueduct, considering how important it was? I mean, stopping people from dumping random things into it, pooping in it, etc.",
"I might be misinterpreting your question, but it sounds like you are asking if people used boats or swam in the aqueducts. Is this correct?\n\n\n",
"The trouble is that an 'aqueduct' is not simply a viaduct that water travels through. Indeed, you generally wanted, for security and maintenance purposes, as little to be built on arches as possible. Rather, aqueducts were long-distance pipes, moving water using gravity by way of an almost minuscule gradient, and designed to be fully enclosed. And the safest, lowest-maintenance place to lay a pipe? Underground.\n\nA look at [this map](_URL_0_) of the section of the Nîmes aqueduct near the famous [Pont Du Gard](_URL_2_) of Provence illustrates my point exactly – the channel cuts through a large hill, zigzagging as it goes. The situation with the Roman supply was similar. The oldest aqueduct, the Appia, roughly 16.5km long, ran on arches for only 90m before reaching the city walls. The least underground aqueduct, the Aqua Julia, ran above-ground for all but 3 of its 23-kilometre length, but was anomalous in this regard.\n\nSo we've established that aqueducts were largely underground and thus a pretty horrible way to travel. But have we even established it was possible to travel through them? Well, I have actually been inside the Pont du Gard, and [this](_URL_1_) is roughly what I saw (not my picture but it illustrates my point exactly). See how the sides 'pinch' inwards at the bottom? That's not actually original material – it's mineral deposits left behind after centuries of use, and you can tell where the water level generally was by the height of these deposits – and it's quite obvious that the space between the top of the water and the ceiling was maybe about a foot. It would be pretty hard to swim down that, let alone boat up it.\n"
]
}
|
[] |
[] |
[
[],
[],
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"http://www.romanaqueducts.info/aquasite/foto/pontdugardarea.jpg",
"https://media-cdn.tripadvisor.com/media/photo-s/04/6a/e0/06/mineral-deposits-on-the.jpg",
"http://www.pontdugard.fr/sites/default/files//1_0.jpg"
]
] |
|
4fr4on
|
How do voting machines work and why would we need to audit something as simple as a vote count?
|
To a simpleton like myself, an average smartphone seems far more complicated than a machine that counts "Votes for H" and "Votes for B."
How do the voting machines responsible for counting votes actually work?
How could something so simple be the subject of fraud? How could that fraud be detected and rectified?
|
askscience
|
https://www.reddit.com/r/askscience/comments/4fr4on/how_do_voting_machines_work_and_why_would_we_need/
|
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"text": [
"I can't speak to the specifics of the inner workings of the voting machines themselves, but I do work in IT Security and can discuss some of the latter questions.\n\n > How could something so simple be the subject of fraud?\n\nThis all boils down to something akin to what's known as a \"Man-in-middle-attack.\" MitM attacks are so called because you interrupt the stream of data. Sometimes you're merely listening in, and other times you're halting the flow of data (votes in this case), and manipulating said data before sending it. \n\nSay Person A walks up to the booth and selects Candidate A. The man in the middle says, \"I like Candidate A,\" and let's the vote pass on to the recipient unchanged. Now Person B attempts to vote for Candidate B, and the attacker doesn't like Candidate B. He intercepts the communication of B's vote to the counting server, or local storage and changes it to Candidate A. \n\nIf a response is sent from the server, well all he has to do is intercept the response and change it. Et Voila! You just stole someone's vote and there's no real record of it happening. \n\n > How could that fraud be detected and rectified?\n\nThat's a very tricky question. There are methods of securing the machine so that it can't run code that someone else supplies. This security mechanism isn't foolproof though, as new exploits are found every day. Someone attempting something on this scale would already have their hands on the hardware and could code something very sophisticated and hard to trace. \n\nYou can mitigate that threat by updating the software regularly, making sure to patch any discovered exploits, and hardening defenses proactively. ",
"[This video is a decent overview.](_URL_0_)\n\nWhen you make a phone call, the telcom company knows what phone is making the call. When you vote, you don't sign your name, so how can you tell if the vote was legitimate? Voting machines are generally made by 3rd parties, with proprietary programming that nobody is allowed to see. So there is no simple way to prove there was fraud, and no simple way to prove there wasn't. \n\nIn my opinion the bottom line is that people trust people and don't trust machines- an open source voting machine can't be proven secure, but it can be made so we are reasonably sure it is secure. Even among experts, the opinion of this idea is generally very low. Tech people tend to believe, with good reason, that there is no such thing as a program without bugs, or a secure program. When you have enough money, smart enough people, and enough time, you can make programs and systems that have no detectable weaknesses. Critical embedded systems, and super important systems (like in NASA) have shown this. The hardest part about making a system like that is assembling the team to do it. You have to trust that team absolutely, or electronic voting could hypothetically make massive-scale voter fraud trivial and undetectable.",
" > why would we need to audit something as simple as a vote count?\n\nThere will be too many people trying to fake it, many of them are smart enough to succeed even against a somewhat sophisticated security system.\n\nThere will be too many people questioning its authenticity, and it's the state's responsibility to *prove* it.\n\n > How could something so simple be the subject of fraud?\n\nSuppose you have a central computer storing the count in a file (actually, for security reasons, this will never be that simple). Who's the system administrator or who has the root/administrator password? For that person, it'd be as simple as modifying the file. Therefore, they will try to make a more sophisticated system where such modifications can be prevented or at least audited. It should *at least* involve redundancy, so that a single person can't change all participating systems.\n\nEven if the machine holding the count were just one, it's receiving vote counts from many different geographically distributed locations. Those will be messages over a network, and they are very easy to fake unless cryptography is appropriately used (and anyway note that crypto only makes it *hard*, not impossible).\n\nBasically, you need to use several redundant machines to store the counts, with appropriate cyphering and auditing to prevent fraud in them, and authenticate all messages transmitted over a network.\n\n > How could that fraud be detected and rectified?\n\nWhen protecting a message, we normally consider *authenticity* and *integrity* as two different things. \n\n*Authenticity* means making sure the message actually originated from its stated sender. If you receive an email from the prince of Nigeria, how do you know it's actually the prince and not just a hacker in his garage? Clearly you have to ask for something that only the intended sender can know, like a password or a cyphering key.\n\n*Integrity* means making sure the message hasn't been modified while in transit. Data packets over a network will traverse several routers and switches, becoming vulnerable to several attackers that will try to manipulate those systems to change the message (the man-in-the-middle attack as /u/darkstarohio said). You need an extra code that is consistent with the message if and only if it hasn't been altered.\n\nThe normal way of achieving both is appending a [keyed hash](_URL_0_) to the actual message. If the message has been altered in any way, then the hash will not match and the receiver will be able to realize. Faking the hash will be extremely hard since attackers (hopefully) don't know the sender's key.\n\nSmall clarification: \"hard\" in this context means that a lot of processor time will be required to test all possible keys. If cryptography is strong enough then the order of magnitude of this time is years, so that being able to fake the information will be completely useless by then. Of course, keys change every few years so that you can't guess them before they expire.\n",
"To guarantee the result of an electronic votes, you need to audit & certify all of the following: \n\n - the physical machine running the vote, \n - all of the software running on the machine (including OS + voting software), \n - the infrastructure used for tallying the votes, \n - the state of the machine before, during and after the vote (= no ballot box stuffing), \n - also, the math used to count the votes and protect voter anonymity.\n\nTo this day, we basically cannot do *any* of these steps right. Voters using a voting machine cannot have a proof that their vote was correctly cast. The machine is badly audited (google Diebold for amusing anecdotes...). The software could be manipulated, and there are even cases of **unintentional** errors (such as, a 4096-vote discrepancy in the Netherlands). And, more seriously, the math for a fully end-to-end auditable and privacy-preserving voting system **does not exist yet** (although research on this is ongoing)."
]
}
|
[] |
[] |
[
[],
[
"https://www.youtube.com/watch?v=w3_0x6oaDmI"
],
[
"https://en.wikipedia.org/wiki/Hash-based_message_authentication_code"
],
[]
] |
|
2xutms
|
Why can't we determine where an electron is located? If time were stopped and you had an omniscient point of view, could you determine all the properties of an electron?
|
askscience
|
http://www.reddit.com/r/askscience/comments/2xutms/why_cant_we_determine_where_an_electron_is/
|
{
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2
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"text": [
"What you have to understand is that the fuzziness of the electron's location is not a result of our imperfect ability to measure its position, but is an intrinsic property of the electron itself. You can't think of an electron as a point-like marble, the position of which is simply not known exactly. Rather, electrons, just like all particles have a wavelike character, and like all waves they are subject to [a fundamental uncertainty](_URL_2_) between knowledge of their wavelength/energy on the one hand and their position on the other. For a wave to have an exactly known wavelength, it would have to be infinitely delocalized spatially. However by adding waves of different frequencies we can obtain a so-called wave packet, the spatial position of which becomes increasingly more defined, as shown [in this nice animation from Wikipedia](_URL_3_).\n\nThe implication of this property is that the [wavefunction](_URL_0_), or its [spatial representation](_URL_1_) *is* the most complete information you can have about a particle. In other words, the shape (and phase) of the electron \"cloud\" represents the complete description of the system, you simply can't say anything more about it! ",
"The electron physically cannot be in a state where both the position and momentum are defined precisely at the same time (it is actually mathematically impossible in quantum mechanics). It is not that we can't measure it. It is that it is purely not determined. You can interact with an electron in such a way where its position will be exactly determined, but by interacting with the electron, it is now in a state where position is determined but momentum is completely undetermined. Similarly you can interact with it in such a way to measure momentum exactly, but now position is completely undetermined. The only thing that omniscient you could see is the wavefunction of the electron itself, which would tell you the probabilities of where the electron might be and how fast it might be going."
]
}
|
[] |
[] |
[
[
"http://en.wikipedia.org/wiki/Wave_function",
"http://upload.wikimedia.org/wikipedia/commons/c/cf/HAtomOrbitals.png",
"http://en.wikipedia.org/wiki/Uncertainty_principle#Wave_mechanics_interpretation.5B9.5D.5Bpage.C2.A0needed.5D",
"http://upload.wikimedia.org/wikipedia/en/d/db/Sequential_superposition_of_plane_waves.gif"
],
[]
] |
||
2nyimt
|
How massive was the flight of German civilians during the end of WWII?
|
I understand that Prussia had the biggest amount of civilians leaving their homes fearing the Red Army. What were the other major regions? How many refugees left and how many made it alive? Did most of them left for Western Germany or there were other notable destinations? When did the mass flight start? How did Wehrmacht high command react to it?
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/2nyimt/how_massive_was_the_flight_of_german_civilians/
|
{
"a_id": [
"cmi5h5r"
],
"score": [
2
],
"text": [
"I'll respond beginning with the last question.\n\nHitler commanded the Wehrmacht to destroy every german house, kill every german civilian, whipe out everything that could even leave a clue of people ever living in germany. \n\nWhy? Well, mostly because in his mind, the german people let themselves, and most of all him down during the war. They didn't win, therefore they don't deserve to even exist. But also it was supposed to let the invaders down when trying to find anything useful. \n\n\n\nIt was one of the most perverted commands ever given during that war, at least to the regular Wehrmacht. Luckily though, most of them ignored that and surrendered. \n\nEven after the war, there were the so-called \"Werwölfe\" (Werewolves), basically Hitler-Youth 'soldiers' who were taught in something similar to guerilla-warfare. But most of these terror-acts failed, seeing as those 'terrorists' were basically still children, that's not a big suprise.\n\n\nThe people left basically all the eastern areas, that's Pommern, too, for example, and as you said, mainly Prussia. Really, at least 60% of the refugees came from there, and that's because in Prussia the Red Army was exceptionally brutal, since it looked beautiful there, and they were quite mad to see how good a german worker lived. \n\nMost of them tried to get to West-Germany, yes. Mainly because they heard that the british and american soldiers weren't as cruel as the Red Army was. And, eventhough they did commit a few crimes (random killing, theft, rape), those rumors were true, living in the west guaranteed you an easier life. (This is still true, btw.)\n\nIt started with the Wehrmacht moving backwards. As soon as they saw their own soldiers running, they got ready to run, too. \n\nI'm sorry this answer isn't really organized, but I hope it answered some of your questions. \n\n"
]
}
|
[] |
[] |
[
[]
] |
|
8k5xqv
|
Do volcanic eruptions, such as the one currently happening in Hawaii, have an effect on global temperature?
|
With the recent ongoing eruption of Kilauea in Hawaii, and the subsequent plume of ash being tossed into the atmosphere from it's summit, will such an event impact the global climate in any significant way? If so, in what manner? Thanks!
|
askscience
|
https://www.reddit.com/r/askscience/comments/8k5xqv/do_volcanic_eruptions_such_as_the_one_currently/
|
{
"a_id": [
"dz59fmk"
],
"score": [
12
],
"text": [
"Yes, but no.\n\nThe current Kilauea eruption is not outgasing or putting enough ash into the air to create a marked effect on the global climate.\n\nHowever, there have been volcanic eruptions in the past, Krakatoa, The Siberian Steps, Tambora, Pinatubo, etc. that have had noticable effects, both in global cooling and global warming."
]
}
|
[] |
[] |
[
[]
] |
|
7cbbje
|
what is "brainfreeze"?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/7cbbje/eli5what_is_brainfreeze/
|
{
"a_id": [
"dpoldlk"
],
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"text": [
"Your brain uses the temperature sensing nerves at the back of your throat to judge extreme cold. Those nerves are relatively deep in the body while still exposed to the outside. If they're cold, your environment is likely *very* cold. Your body raises its internal temperature to compensate. Specifically, it increases your brain temperature. It's a fever, but instead of helping the body kill germs, it's protecting your brain from extreme cold.\n\nIce cream and smoothies and other frozen treats are very new on a biological time scale. When you eat too much of it too fast, your body responds like it would in extreme cold.\n\nThis is why pressing your tongue against the back of your throat helps. Tongues are warm and full of blood, and they help return those nerves to normal."
]
}
|
[] |
[] |
[
[]
] |
||
334wt0
|
When we rip paper, are we breaking covalent bonds or just hydrogen bonding between molecules?
|
Other examples would be cutting plastic with scissors, snapping a strand of hair, or smashing a rock.
A carbon-oxygen bond (C=O) requires 745 kJ/mol to break the bonds. An AK47 bullet can impart 2kJ, and a human punch weighs in at a measly 100 joules.
So when you tear, rip, punch, or shoot something, are you actually breaking bonds or just separating individual molecules?
|
askscience
|
http://www.reddit.com/r/askscience/comments/334wt0/when_we_rip_paper_are_we_breaking_covalent_bonds/
|
{
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"text": [
"No. \n\nBreaking a bond is a chemical change, but ripping a piece of paper is physical. When you rip paper, you are tearing fibers, that latch onto each other to hold the paper together, apart but no bonds are broken. ",
"The forces that hold together the fibers in the paper are van der Waals forces (forces of attraction and repulsion between molecules, AKA friction). So you're rubbing fibers against each other and possibly breaking a few that were held together by van der Waals forces, hence the force you feel when you rip it, but you're breaking very few molecular bonds if any."
]
}
|
[] |
[] |
[
[],
[]
] |
|
7stpg1
|
how can russians who swim in cold water keep their toes and fingers?
|
I have a big winter coat, winter gloves, winter hat, winter boots, scarf, am walking at a fast pace, and sometimes I STILL feel my fingers and toes are numb due to cold temperature. How is it possible that I could take off all my clothes, jump in cold water, stay for a few minutes and not lose my extremities?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/7stpg1/eli5_how_can_russians_who_swim_in_cold_water_keep/
|
{
"a_id": [
"dt7f8yl",
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"score": [
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7
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"text": [
"Vodka.\n\nNo but for real, us Slavs just naturally feel warm. Most of us get sweaty and irritated at normal temperatures. We take cold showers because we're used to it and that helps with the cold too.",
"The reason you lose your fingers, toes, and other extremities in the cold is due to frostbite, which occurs when your extremities freeze. Your body has shunted blood to your core to keep it warm and functioning, and allowed the temperature in your extremities to drop. If this happens when the air temperature is below freezing, then your extremities can potentially go below freezing, too, and literally freeze. This can cause tremendous damage to the extremities as the icing up of your cells bursts cell walls, plus your cells are deprived of fresh blood long enough to cause them to die.\n\nIn contrast, if you're in an environment that is not below freezing, your extremities won't freeze. They'll get really cold as the body shunts blood away from them, but by definition, they can't freeze since they're not in a below freezing situation. Russians swimming in cold water typically are not swimming in water that is below freezing. And they're not in the water for long. Even if they go swim in salt water, which can dip below freezing (i.e. 32 fahrenheit or zero celsius) since salt water freezes at a colder temperature than fresh water, they're not in the water long enough for their extremities to freeze or to be deprived of blood flow long enough to sustain serious damage. They would die of cold a lot sooner than it would take to get frostbite."
]
}
|
[] |
[] |
[
[],
[]
] |
|
7lrjhb
|
Winston Churchill's "We will fight them on the beaches" speech is viewed as one of the great speeches of history, but what was the contemporary reaction to it?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/7lrjhb/winston_churchills_we_will_fight_them_on_the/
|
{
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"text": [
"Hey all,\n\nIf you frequent the sub, you know the drill. If you're here from /r/all, or browse only occasionally, please be aware we have strict rules here intended to enforce the very high bar we expect from comments, so before posting, please read our [rules](/r/AskHistorians/wiki/rules). Comments not in compliance will be removed on the beaches, removed on the landing grounds, removed on the fields and on the streets, and we consider everyone forewarned. If you have feedback or commentary about how things are run here, please don't post it in this thread. We'll just remove it. We love to hear thoughtful, constructive feedback via [modmail](_URL_2_) however.\n\nIt can take time for [an answer to show up](/r/AskHistorians/comments/6a5duv/a_statistical_analysis_of_10000_raskhistorians/), so we thank you for your patience. We know you're here because the question sounds interesting, and we eagerly await an answer just like you! While you wait though, there is tons of great content already written, which you can find through our [Twitter](_URL_4_), the [Sunday Digest](_URL_1_), the [Monthly \"Best Of\"](_URL_0_) feature, and [Facebook](_URL_3_). If you don't want to forget to check back late, consider a [Private Message](_URL_6_!) to the [Remind-Me bot](_URL_5_).\n\nAgain though, please remember the rules, and keep them in mind while you browse. If you don't like how this subreddit is run, keep in mind that this method has seen us continue to succeed and grow for years, and isn't going to change, so at least try and make your complaint original. /r/AskHistory exists, so complaining about the rules to us is like going into a fancy restaurant to complain they don't sell chicken nuggets, even though Chick-fil-A is nextdoor.",
"Interestingly, almost no-one actually **heard Churchill give that speech** on the 4th of June 1940, made following the remarkable evacuation of most of the British troops stranded at Dunkirk. It was delivered in the House of Commons, but unlike many of Churchill's other famous speeches it wasn't delivered on the radio as well.\n\nSo instead, people heard a BBC announcer reading his words, or read the text of the speech in the next day's newspapers. The recording of Churchill delivering that speech is actually from 1949.\n\nAs for how people responded to it at the time, the responses were rather mixed.\n\nIt's easy to find individuals who eulogised it - Conservative MP Henry Channon wrote that Churchill was ‘eloquent and oratorical, and used magnificent English… several Labour Members cried.’ The speech received particularly high praise from many American media outlets, even isolationist ones such as the *Chicago Daily Tribune*. This is not surprising - the section of the speech vowing that the Empire would continue the fight even if the British Isles fell was specifically tailored to appeal to concerns that Roosevelt had expressed. Churchill even took advice from American newspaper editor William Philip Simms on how to best appeal to an American audience, and deleted a line critical of America's failure to intervene in order to maximise its appeal across the Atlantic.\n\nIn the UK press, the speech was highly lauded but was only given pride of place by two newspapers - *The Daily Mirror* and *The Daily Worker* (the latter was a Communist paper).\n\nHowever, when we turn to measures of mass opinion things don't look quite as good as we might expect. Our main sources for this aspect are:-\n\n* Ministry of Information's Home Intelligence reports - i.e. the government's monitoring of morale and conditions\n* Mass Observation's reports and diaries - this was a massive anthropological project to study the British people's attitudes and interactions. As well as sending out questionnaires on issues, some correspondents kept diaries of conversations overhead in the butcher's etc.\n\nThe Ministry of Information's Home Intelligence report covering the speech noted that:-\n\n > The grave tone of Churchill’s speech made some impression and may have contributed in some measure to the rather pessimistic atmosphere of today. […] The contents of the speech were on the whole expected but some apprehension has been caused throughout the country on account of the PM’s reference to ‘fighting alone’. This has led to some slight increase in doubt about the intentions of our ally [France].\n\nMass Observation summarised reaction to the speeches as:-\n\n > Churchill’s speech has been mentioned frequently and spontaneously this morning. There does not appear to have been a great deal in it which was unexpected, but its grave tone has again made some impression, and may be in part the cause of the depression.\n\nBritish housewife Nella Last wrote in her diary that:-\n\n > We all listened to the news and the account of the Prime Minister’s speech and all felt grave and rather sad about things unsaid rather than said.\n\nSo Churchill's speech was recognised at the time by politicians and press as being a particularly fine example of rhetoric, but it didn't produce any great surge of patriotic effort. People responded to the speech's content more than its style, and the content was fairly depressing - the speech suggested that France would not hold out much longer, and that an invasion of the UK was quite possible. Churchill took over as Prime Minister when there was precious little that wasn't bad news; cheerier speeches would simply not have rung true.\n\nInterestingly, in 1947 Nella Last wrote about that speech again, but in very different terms indeed - she remembered that she 'felt my head rise as if galvanised and a feeling that \"I’ll be there -- count on me; I’ll not fail you\"'. This is a good illustration of how memories of Churchill's early speeches have been re-imagined in hindsight, basked in the glow of the Allied victory.\n\n**Sources:-**\n\n***The Roar of the Lion* - Richard Toye.** This book is entirely focused on Churchill's wartime speeches with a heavy focus on their contemporary reception, and is the #1 source for this. It's worth also checking out reviews of the book (e.g. [this one, which argues that Toye overstates how critical the reception of Churchill's speeches was](_URL_2_) ).\n\nToye's also written [a nice short blog post specifically on the 'We Shall Fight on The Beaches' speech](_URL_3_).\n\n***Listening to Britain* - Addison & Crang (eds.).** This book provides extensive extracts from Home Intelligence reports covering May-September 1940, which includes reports on how Churchill was received by the British public.\n\n[This Smithsonian Magazine article on the speech is also where I got the Nella Last quotes from.](_URL_0_)\n\nLastly, [this previous AskHistorians post on public opinion during the Dunkirk](_URL_1_) might well be interesting to you."
]
}
|
[] |
[] |
[
[
"https://www.reddit.com/r/AskHistorians/wiki/bestof",
"http://www.reddit.com/r/AskHistorians/search?q=title%3A%22Sunday+Digest%22&restrict_sr=on&sort=new&t=all",
"http://www.reddit.com/message/compose?to=%2Fr%2FAskHistorians&subject=Question%20Regarding%20Rules",
"https://www.facebook.com/askhistorians/",
"http://twitter.com/askhistorians",
"https://www.reddit.com/r/RemindMeBot/comments/24duzp/remindmebot_info/",
"https://www.reddit.com/message/compose/?to=RemindMeBot&subject=Reminder&message=%5BLINK%20INSIDE%20SQUARE%20BRACKETS%20else%20default%20to%20FAQs%5D%0A%0ANOTE:%20Don%27t%20forget%20to%20add%20the%20time%20options%20after%20the%20command.%0A%0ARemindMe"
],
[
"https://www.smithsonianmag.com/history/winston-churchills-historic-fight-them-beaches-speech-wasnt-heard-public-until-after-wwii-180967278/",
"https://www.reddit.com/r/AskHistorians/comments/4waexw/what_was_the_general_public_perception_of_dunkirk/",
"http://www.history.ac.uk/reviews/review/1542",
"https://history.blog.gov.uk/2013/12/02/we-shall-fight-on-the-beaches-three-things-you-never-knew-about-churchills-most-famous-speech/"
]
] |
||
38odvk
|
why do white people have such unusual names ie. tagg, scooter, buck, apple, skylar? where do they come from? or do their parents just make them up?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/38odvk/eli5_why_do_white_people_have_such_unusual_names/
|
{
"a_id": [
"crwi3nt",
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2
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"text": [
"Every ethnicity has unusual names, it's not something specific to white people. Some are made up, others are passed down generation to generation. Beyonce named her kid Blue -- that's also unusual.",
"How on earth is Skylar unusual? The other ones are usually nicknames. "
]
}
|
[] |
[] |
[
[],
[]
] |
||
6cusg3
|
Was the communist takeover of Poland post-WWII an unfortunate necessity to finally unseat the gentry...allowing an eventual functioning Democratic Republic to form?
|
The feudal system in Poland seemed to linger on longer than most European countries. Many have cited the "Golden Freedom" and liberatum veto of the Polish nobility as factors that, along with bribes from foreign powers, prevented any real unity and lead to the partition. How much power did the Gentry regain after Poland was re-established after WWI and did the communist period finally stamp it out for good?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/6cusg3/was_the_communist_takeover_of_poland_postwwii_an/
|
{
"a_id": [
"dhxv7yj"
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"text": [
"Although the Polish communist parties defined the *szlachta* land-owning gentry as one of the Polish nation's class enemies and defined feudalism as a retrograde socioeconomic order, the reality was the *szlachta* was a class very much on the wane in 1944/45. The *szlachta* itself had undergone a transformation in the 130 years since the final partitions of Poland during the Congress of Vienna. \n\nOne of the problems in Polish historiography is how to define the *szlachta*, the land-owning gentry. In terms of both their size and political culture, the nobility of the Polish-Lithuanian Commonwealth was somewhat unique estate in East Central Europe. In terms of numbers, they were rather large and the political culture of the Commonwealth stressed collective equality before the law between members of the *szlachta*. There were of course large differences in wealth within this particular estate , with some of the *szlachta* living in conditions that were not that much better off than wealthy peasants, and political power in the waning days of the Commonwealth shifted towards the larger magnates and landowners. But the existence of such a large and variegated noble estate posed a problem for the Partition powers. The Galician *szlachta* arguably managed the transition the best by intermarrying with Austrian officials and posing as a *kaisertreu* estate that was bound to the Habsburgs by bounds of personal loyalty. Prussia's share of Poland largely displaced the smaller *szlachta*, but the larger magnates and land-owners tended to try and work with the local and central governments as a power bloc. The advent of constitutionalism and the franchise in Prussia led the Polish nobles to band together in common political cause as a distinct political party, the Polish Casino, and made alliances with German conservative parties and, later, the catholic *Zentrum*. \n\nBut it was in Russian Poland that the *szlachta* ran into the greatest difficulties with the Partition power. Alexander I's pet project of a liberal Poland proved to be short-lived and there was a strong streak of Polonophobia within the Romanov state apparatus. Imperial officials had internalized a distrust of Poles and these sentiments were given freer reign with the succession of the archconservative Nicholas I to the throne. Polish nobles' connection to the Decemberist officers as well as Alexander I's project in Poland ensured that the days of Congress Poland's even nominal independence were numbered.\n\nThe revolts of 1831 and 1863 proved collectively to be the caesuras for Russia's Polish policies. Although the institution of nobility remained sacrosanct for the Romanovs, the administrative abolition of the Kingdom and its replacement as the Western Provinces ended attempts by the imperial state to co-opt the nobility by offering them local power. Educated Poles were forbidden by law from entering into the Western Provinces' bureaucracies and the anti-Polish legislation gained new currency after the 1863 revolt as \"Polish/Latin\" culture became a byword for latent treason in the ruling circles of the empire. The Russian state could expropriate Polish estates for expected treason and the state also tightened both censorship of the Polish public sphere and the Catholic Church. Nor were loyal Polish nobles extended the same privileges as their Great Russian counterparts. Although the Great Reforms did lead to the final end of serfdom in the Western Provinces, they explicitly did not extend the local institution of the *zemstvo* to them as this would have given Polish nobles too much control over local affairs in their capacity as Land Captains. The issue of extending the *zemstava* to the Western Provinces remained a third rail in Russian politics through 1914 and was one of the major issues that damaged the latter career of Stolypin before his assassination. \n\nThe collective response of the *szlachta* during the nineteenth-century Partitions was to turn inwards. While some of the richer magnates played with the existing system of imperial rule, this was not as much of an option for the poorer members of the gentry. Many of them instead filtered into Polish cities as a déclassé strata of Polish society. Some of the nobility filtered into the nascent middle class while others could still capitalize on their education and personal backgrounds to become the patrons of Polish Romanticism and incipient nationalism. \n\nThis use of the power of culture did allow the *szlachta* to retain a veneer of their status and importance during the Fin de siècle, but this was clearly a social estate whose power was on the wane. The Marxist-inspired socialist parties in Poland not only saw the Russian imperial control over Poland as a problem, but framed the old Polish aristocracy as one of the exploiters of the Polish peasantry and workers. The picture of the *szlachta* as an petty vain aristocrats desperately trying to hide their poverty became one of the tropes in Polish literature in this period such as I. L. Peretz's novels. Even the larger magnates found little room in the twentieth-century Neither Austria-Hungary nor Germany's mass politics could easily accommodate Polish nationalism and one of the persistent concerns within the German press in the 1900s was that Poles were outbreeding German settlers in Prussian Poland and the magnates were leading a Catholic-Pole fifth column against German interests. \n\nNonetheless, the *szlachta* collectively did have a degree of political capital when independence finally came during the First World War. All three of the Partition powers recognized during the war that victory would mean some resuscitation of the Polish nation and hopes to use the aristocracy and other conservative elements within Poland to ensure that such a Poland would be a safe client state. Józef Piłsudski was one example of how some of the *szlachta* found a role in this charged environment. But despite some noble blood in the leadership of the Polish movement, the political parties of the Second Polish Republic eschewed the idea of the nobility being a separate, elevated estate. The large landowners still had an outsized political importance in rural Poland and Polish nobles also managed to colonize significant portions of the army and elite governmental circles. Yet, contrary to Soviet and communist claims that the Republic was just window-dressing for noble and landlord rule, the *szlachta* was definitely a declining social group. The size of estates went down and the socioeconomic power of the *szlachta* declined during the Republic. Their fortunes took a further hit during the Second World War. Nobles and landlords were class enemies in Soviet half of Molotov-Ribbentrop Poland and massacres and the disestablishment of estates were the hallmarks of Soviet administration. Polish landowners also suffered expropriations within those areas of Poland directly annexed to the Reich, but managed to preserve some degree of limited power within the General Government. Hans Frank, for all of his racism and venality, did style himself as a colonial overlord and pushed for a German-controlled Poland with the nobility and other Polish elite acting as German lieutenants. These projects never went very far but they did help cement an image of the *szlachta* as politically suspect opportunists. The fact that some landowners did entertain various Reich officials though should not obscure the fact that a number of aristocrats and other former elite took up leadership positions within the Home Army and other resistance organizations. \n\nThese wartime activities as well as their own self-described class backgrounds were the major reasons why Stalin and his Polish allies felt that the *szlachta* needed to have its back broken when the Red Army reoccupied Poland over the course of 1944/45. In common with other land reforms that followed in the wake of the Red Army, the provisional Polish government broke up large estates as a means to break the political power of what they believed was an inherently reactionary social class. The classification of landed gentry soon became a epithet by the state for foolhardy resistance to communism and short-hand for disloyalty. The *szlachta* became an object of scorn within the Polish academy during the communist period as the hybrid nationalist-communism of the later Gomułka period portrayed this feudal aristocracy as a self-interested class who sold the nation out to preserve their own waning power. But despite this scorn, the Gomułka era also tried to have its cake and eat it too; while the *szlachta* were enemies of the people, the Polish state valorized the freedom of the Commonwealth and contended that under Soviet-style socialism, the Polish worker had become the new *szlachta* in the people's state. \n\nWhile the some apologists for Polish communism cite the elimination of the landlords and nobility as a necessity for Poland to evolve, the fact is the *szlachta* was very much a spent socioeconomic class by 1945. The burdens of war was only one of many different factors that ate into their economic and political clout. The *szlachta*'s cultural capital and social networks had allowed it to have a brief resurgence within the interwar Republic, but this could not arrest their larger decline. The importance of the *szlachta* as a phantom enemy to Polish socialism in the postwar period obscures how insignificant the gentry had become by the time the Soviets rolled into the country at the end of the war. \n\n"
]
}
|
[] |
[] |
[
[]
] |
|
jalj9
|
The relationship between the human mind and numbers
|
Is there any evidence that the human mind has a natural predisposition towards counting/measurement/numbers or is Mathematics and measurement as a fundamental property of science more a result of historical circumstance?
|
askscience
|
http://www.reddit.com/r/askscience/comments/jalj9/the_relationship_between_the_human_mind_and/
|
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"text": [
"Humans have an innate ability to count, that is greater than most animals but worse than a good number of them too. Some animals have counting/measurement skills that *far* out-shadow our own. But yes, humans are better are numbers than the vast majority of life forms on this planet - so you could absolutely count that as a 'natural predisposition' if you are talking about strict *ability*.\n\nHowever, if you are interesting in the human *enthusiasm* to pursue mathematics... that is much less clear. It is at least substantially based on cultural and historical circumstance. That being said, the vast collection of cultures that have, in isolated societies (through both space and time), developed some developed form of mathematics *suggests* that it is likely to also be substantially based on innate human nature. However, to the best of my knowledge, no one has found a way to *test* for how innately curious humans are about math/numbers.",
"Yup:\n_URL_0_\n\n(That is to say, if we can develop a deficit in something by damage to parts of our brain, we're wired for it.)",
"Humans have an innate ability to count, that is greater than most animals but worse than a good number of them too. Some animals have counting/measurement skills that *far* out-shadow our own. But yes, humans are better are numbers than the vast majority of life forms on this planet - so you could absolutely count that as a 'natural predisposition' if you are talking about strict *ability*.\n\nHowever, if you are interesting in the human *enthusiasm* to pursue mathematics... that is much less clear. It is at least substantially based on cultural and historical circumstance. That being said, the vast collection of cultures that have, in isolated societies (through both space and time), developed some developed form of mathematics *suggests* that it is likely to also be substantially based on innate human nature. However, to the best of my knowledge, no one has found a way to *test* for how innately curious humans are about math/numbers.",
"Yup:\n_URL_0_\n\n(That is to say, if we can develop a deficit in something by damage to parts of our brain, we're wired for it.)"
]
}
|
[] |
[] |
[
[],
[
"http://en.wikipedia.org/wiki/Acalculia"
],
[],
[
"http://en.wikipedia.org/wiki/Acalculia"
]
] |
|
3gilg7
|
Are raccoons and Pandas related?
|
giraffee.
|
askscience
|
http://www.reddit.com/r/askscience/comments/3gilg7/are_raccoons_and_pandas_related/
|
{
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"ctzrz82"
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"text": [
"This is a question with a lot of answers. \nIn as much as they're animals they're related not only to each other, but also to you and sea sponges. \nBut of course they're more closely related to one another than they are to you and I. \nWe'll also need first to define 'panda'. There's the [giant panda](_URL_2_), which is most likely what you meant(?), and that animal is a bear. \nBut there's also the [red panda](_URL_3_) which is another Chinese native but it's not a bear at all, but it is undeniably one of the [cutest](_URL_1_) animals that's alive today. \n \n \nThe giant panda is in the bear family ([*Ursidae*](_URL_5_)). The red panda is in the family [*Ailuridae*](_URL_7_) which is monotypic (meaning that they're the only members of that family). And the racoon is in the family [*Procyonidae*.](_URL_8_) \nAnd all of those families are in the order [*Carnivora*](_URL_4_). \n \n[So lets look at a good phylogenetic tree for the *Carnivora*.](_URL_4_#Phylogenetic_tree) \n \nIf you scroll down a little you'll see that all three of those groups are among the [*Caniformia*](_URL_6_) and they're all within the *Arctoidea*. But then the *Ursids* (bears, including the giant panda) are on a different branch from the *Procyonids* and the *Ailuridae*. So that's as closely related as the giant panda is to the racoon. \n \nBut the red panda and the racoon are more closely related. They're both within the [*Musteloidea*](_URL_0_) which also includes the weasel family and the skunks. \n \nSo the \"pandas\" aren't a real group at all. They include members of two different groups of *Carnivorans*. But they're both in the *Carnivora*, so they're more closely to each other than they are to you and I and they're both in the *Caniformia* so they're also more closely to each other than they are to cats. The giant panda is pretty close to the raccoon, but not as close as the walrus is. And the red panda and the raccoon are actually much more closely related to each other than either one is to the giant panda. "
]
}
|
[] |
[] |
[
[
"https://en.wikipedia.org/wiki/Musteloidea",
"https://www.google.com/search?q=red+panda&newwindow=1&espv=2&biw=1366&bih=643&source=lnms&tbm=isch&sa=X&ved=0CAYQ_AUoAWoVChMI--mRx5SixwIVyCuICh3eWAkL#newwindow=1&tbm=isch&q=cute+red+panda",
"https://www.google.com/search?q=red+panda&newwindow=1&espv=2&biw=1366&bih=643&source=lnms&tbm=isch&sa=X&ved=0CAYQ_AUoAWoVChMI--mRx5SixwIVyCuICh3eWAkL#newwindow=1&tbm=isch&q=giant+panda",
"https://en.wikipedia.org/wiki/Red_panda",
"https://en.wikipedia.org/wiki/Carnivora",
"https://en.wikipedia.org/wiki/Bear",
"https://en.wikipedia.org/wiki/Caniformia#Phylogeny",
"https://en.wikipedia.org/wiki/Ailuridae",
"https://en.wikipedia.org/wiki/Procyonidae",
"https://en.wikipedia.org/wiki/Carnivora#Phylogenetic_tree"
]
] |
|
2eomjs
|
What determines whether the light hitting an object is being transmitted or reflected?
|
I've been reading [this](_URL_0_) answer to an earlier question of another poster.
I really liked the answer, unfortunately however, the poster failed to mention what exactly determines whether the light hitting an object is being transmitted or reflected
|
askscience
|
http://www.reddit.com/r/askscience/comments/2eomjs/what_determines_whether_the_light_hitting_an/
|
{
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"ck1hfkv"
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"text": [
"We can describe this without going into the microscopic physics, which is a bit obscure. Suppose that the wave is traveling in a medium (such as air or water) that has an index of refraction.\n\nIf the struck object is an insulator (like glass), the reflection and transmission depend on the indices of refraction of the two materials. If the two indices are equal, the light will always be transmitted. The more the two indices differ, the larger the intensity the reflected light. None will be absorbed.\n\nIf the struck object is a perfect conductor all the light will be reflected. If the object is not perfect (ie, has some electrical resistance), then some light will be absorbed (energy is lost in the resistance). Light will not penetrate very far into any reasonably good conductor.\n\nI realize that this is all qualitative; I hope it's the level of detail you are looking for."
]
}
|
[] |
[
"http://www.reddit.com/r/askscience/comments/2eob2v/what_determines_what_color_an_object_is/ck1g2wj"
] |
[
[]
] |
|
3vjucy
|
Geologists/Earth Scientists: Will all the current land on earth eventually be "refreshed" via subduction?
|
I understand that we are talking about geologic time here, a long long time. The heart of my question is a wondering whether the current surface of the earth, on which every mountain, river, and of course human-built structure stands, will one day be pulled under the earth via subduction, buried under miles of rock, and eventually melted. Will there be new land created via volcano, etc., which eventually cools, and is covered in sediment, and on which new life eventually grows? I'm assuming that human life on probably earth will end in the near future, in geologic time terms. So there will be no one to alter the earth in any way, build permanent structures, etc. I'm just curious whether the current landscape, including everything human-built, will eventually disappear. Not just buried, but eventually melted into molten rock and all traces of it gone forever.
I have entirely separate questions related to this, but they're not geologic in nature, but rather more life science/evolution, so I'll refrain from asking them here.
|
askscience
|
https://www.reddit.com/r/askscience/comments/3vjucy/geologistsearth_scientists_will_all_the_current/
|
{
"a_id": [
"cxo8mre"
],
"score": [
8
],
"text": [
"A simple steady state mass balance approach that gets to an estimate of the time it takes to recycle the continental crust:\n\nThe answer is that the crust is recycled, but not really in the way you're thinking of. Continental crust (CC) isn't really subducted much. Because oceanic crust is denser, when an oceanic plate collides with a continental plate, the oceanic plate will be the one subducted, while the continental plate stays on top. So the material that gets recycled and re-introduced by arc volcanism is largely ocean crust (similar to the mantle), and the sediments sitting on top of it.\n\nYou can also see this in the [age distributions of continental crust](_URL_1_). The average continental crust was formed ~2 billion years ago, and most of the crust was formed as a part of 3-4 major crust building events. So over billions and billions of years the continental crust persists on the earth. \n\nA good approximation you can make to determine the rate of CC returning to the mantle (equivalent to the subduction you ask about) is that of steady state. So, if we know the rate of CC formation today, and we know the amount of CC on earth isn't changing much, we can say that the amount of CC being lost to the mantle is roughly equivalent to the new CC being formed. That is, d(CC)/dt = CC_formed - CC_lost. We set d(CC)/dt equal to zero, So to a first approximation, CC_formed ~= CC_lost. So if we can determine either CC_formed or CC_lost (both rates), we can perform a residence time calculation. Residence time defined as the average amount of time something spends in a given reservoir or system. We want to know the average amount of time some mass of the continental crust spends on the surface before it is subducted - this will give us a rough estimate of the time it takes to recycle and regenerate the entire CC. \n\nResidence time (Tr) = (total mass or volume of crust)/input or loss rate. It turns out the easiest place to calculate a loss is in subducting sediments. But it's not the CC itself being subducted - it's the sediment sitting on top of the ocean crust that has been weathered from the continents into the oceans. \n\nEstimates of loss of CC to the mantle from sediments being subducted center around 0.7 km^(3)/year [(Plank and Langmuir 1998)](_URL_0_). Let's round that to 1 to make the math easy. Now let's estimate the volume of Earth's continental crust. \n\nContinents cover ~30% of the earth, so the area of CC is Area_earth x 0.3 is about 5x10^(8) km^(2) x 0.3 = 1.5x10^(8) km^(2). \n\nNow multiply by the average depth of the continental crust (about 40 km) to get the total volume of continental crust on Earth. \n1.5x10^(8) km^(2) x 40 km = 6x10^(9) km^(3). \n\nNow we have our reservoir (volume of CC on Earth) and our flux (from subduction of sediments). Let's calculate the residence time and see how long it will take to recycle the whole CC (again, assuming steady state). \n\nWell, since our estimate is 1 km^(3)/year, we just have 6x10^(9) km^(3) / 1 km^(3)/year = 6x10^(9) years, or 6 billion years. This is more than the current age of the Earth! \n\n\n**tl;dr It will take about 6 billion years to completely recycle the continental crust.**\n"
]
}
|
[] |
[] |
[
[
"http://www.sciencedirect.com/science/article/pii/S0009254197001502",
"http://www.virtualexplorer.com.au/article/2003/79/interaction-of-mantle-plume-with-india/media/figure25.png"
]
] |
|
azexkc
|
why does cheese stick to the spoon when you put it into hot soup?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/azexkc/eli5_why_does_cheese_stick_to_the_spoon_when_you/
|
{
"a_id": [
"ei7l2nm"
],
"score": [
5
],
"text": [
"The spoon is colder than the soup, so when the melted cheese touches it it partially solidifies and grabs onto the spoon. "
]
}
|
[] |
[] |
[
[]
] |
||
12v177
|
why do i get sharp pains in my head.
|
On occasion I get sharp piercing pains on the left side of my head. They instantly go away and there is so residing pain afterwards. I don't see anything that is consistent in what I'm doing at the time of the pain. The pain is enough to make me cringe and close
my eyes.
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/12v177/eli5_why_do_i_get_sharp_pains_in_my_head/
|
{
"a_id": [
"c6ybxmb",
"c6ycbq4"
],
"score": [
3,
2
],
"text": [
"You should probably ask a doctor.",
"I sometimes, though rarely, get random pains in the head or other places too. Does it happen irregularly for you as well?\n\nIt's not so serious or often to me, but if it is to you it might be something you should take seriously.\n\nJust now I found online that these sharp pains in the head in smaller part of the head, lasting from seconds to minutes, are innocent despite being annoying. "
]
}
|
[] |
[] |
[
[],
[]
] |
|
culnz5
|
If I get a vaccine and then get tested for the same disease would I test positive?
|
askscience
|
https://www.reddit.com/r/askscience/comments/culnz5/if_i_get_a_vaccine_and_then_get_tested_for_the/
|
{
"a_id": [
"ey1n882",
"fcjppq3"
],
"score": [
5,
2
],
"text": [
"It depends on the kind of test. \n\nSome tests check for immunity. Those cannot distinguish between a person who had the disease versus a person who was vaccinated. One example of this is the tuberculosis skin test. A positive test means you have antibodies against tuberculosis, which can mean either that you were exposed to it, or that you got vaccinated against it. \n\nSome tests look for actual symptoms of the disease. An example of that would be a chest x-ray. The active disease of tuberculosis causes changes on the x-ray, but a vaccination does not.",
"Another example is hep B testing. There are two tests, hep B surface antigen (HBSag) and hep B antibodies (HBAb).\n\nIf you test negative for HBSAg, but positive for HBAb, you have either had hep B in the past but fully recovered (about 90% of people who have had hep B), OR you have been vaccinated.\n\nIf you test positive for HBSAg, you have acute or chronic hep B. (Chronic hep B affects about 9% of people who contract hep B. The other 1% die from the acute infection.) Chronic hep B can be spread via blood and body fluids, and is required for the person to be able to contact hep D."
]
}
|
[] |
[] |
[
[],
[]
] |
||
1kpb23
|
Can someone explain the biological process behind getting used to inhaling cigarette/whatever smoke?
|
askscience
|
http://www.reddit.com/r/askscience/comments/1kpb23/can_someone_explain_the_biological_process_behind/
|
{
"a_id": [
"cbr8nvp"
],
"score": [
14
],
"text": [
"Your body will adapt to the smoke, by making the lungs expand more in order to attempt to get more oxygen into them. Same thing will happen with any reduced oxygen situation such as living higher in the mountains. They will actually expand well beyond their normal size in some cases. This is part of the problems with smoking. Over time, this hyperinflation can eventually take a toll on your pulmonary muscles, affecting their elasticity, which can impede the process of exhalation. If you're unable to fully exhale, carbon dioxide becomes trapped, and you're now inhaling less oxygen while maintaining more carbon dioxide within your body, creating an unhealthy exchange of gas whether you are smoking or not. Eventually, this can lead to many other complications depending on your body and genetics. Increases in cancer, etc. I think we all know the potential complications to smoking.\n\nEDIT: Why the down votes, need a source? _URL_0_"
]
}
|
[] |
[] |
[
[
"http://www.ehow.com/how-does_5525323_causes-expanded-lungs.html"
]
] |
||
2fyz23
|
Can this article regarding light being stopped be explained?
|
_URL_0_
I see posts about how they cool the atoms to within a billionth of a degree of absolute zero and, as far as I knew, this was not possible for humans to accomplish. What is the technology and scuence behind this stopped light?
|
askscience
|
http://www.reddit.com/r/askscience/comments/2fyz23/can_this_article_regarding_light_being_stopped_be/
|
{
"a_id": [
"ckejdi4"
],
"score": [
3
],
"text": [
"There are two parts to your question, so let's adress them separately.\n\n*\"I see posts about how they cool the atoms to within a billionth of a degree of absolute zero and, as far as I knew, this was not possible for humans to accomplish.\"* \nThe corresponding temperature would be in the nanoKelvin, which a quick search on the web indicates was beaten at least ten years ago. The way it works generally involves multiple parts, with two main techniques:\n\n* **laser cooling** when an atom absorbs a photon (light), it gets a kick in momentum (which is related to its speed) of kv. If you're clever about it, you can design a system where atoms will absorb light in such a way that they sort of stabilize their speed, as in if they go to fast it kicks them in the other direction. That's a pretty efficient way of doing it but ultimately you are limited and cannot go down too far in temperature (in particular, you are limited by the kick the photons impart on the atoms).\n* **evaporative cooling** The idea here is to trap the atoms in position very strongly, and then release the strengh of your trap slowly. If you do that slowly enough, then the faster atoms (contributing a lot to the temperature) will exit the trap while the slower ones (contributing very little) will stay in the trap. As \"hot\" atoms exit the trap, the cloud of atoms that stayed in the trap is more and more composed of slow atoms (since the fast ones are leaving) so the temperature of the remaining atoms decreases.\n\n*\"What is the technology and scuence behind this stopped light?\"*\n\nWell, the technique used here is frozen light using electromagnetically induced transparency (as far as I know, since it's not to my knowledge said in the article). I'm not going to explain the specifics of the name (it's complicated) but here is the basic idea: When light travels through a medium, you cannot think of the two separately. Instead, what happens is that the \"thing\" that travels in the medium is a mixture (said polariton) of both the electric field (light) and *something* about the medium. In our case, the *something* is a coherence between two atom levels (said spin wave) roughtly speaking. so, said in simpler terms, the thing that propagates inside the medium is part \"light stuff\" and part \"matter stuff\". It turns out that in this case, there is a way to control the proportions of those stuff, that is, how much your polariton has \"light stuff\" compared to \"matter stuff\". So what they do is that, when the light is in the medium, they violently change from \"lots of light, some matter\" to \"mostly matter, almost no light\". The \"matter part\" doesn't travel when alone, so it gets stuck in the medium. Then, at a later time (typically in the order of microseconds) they violently change the state to \"lots of light, little matter\" again, and the polaritons starts propagating again. From the point of view of an outsider that sees light enter the medium, then presses a button, then waits, then presses it again and sees light exit the medium, it seems as if light was stopped inside the medium, hence the name.\n\n**Conclusion/TLDR:** They don't actually stop \"light\". They control some property of the medium such that the light leaves an imprint in the medium for some time, that can at a later date be converted back into light.\n\n*(Edit after rereading: sorry it's confusing, but I can't make it simpler)*"
]
}
|
[] |
[
"http://news.harvard.edu/gazette/2001/01.24/01-stoplight.html"
] |
[
[]
] |
|
1c6zuj
|
Having trouble understanding relativity and time dilation. Specifically as it relates to simultaneity of events in different inertial reference frames.
|
I'm studying for a physics exam and I came across this statement:
"Two events that are simultaneous in one frame of
reference are not simultaneous in a second frame of
reference that is moving relative to the first one,
even if both are inertial frames."
Could someone put this into a real world example (is it possible)? I think I understand, but I'm not sure. If I were standing still (my inertial frame of reference) and my friend was driving a car in a set direction at a high constant velocity (his inertial frame) would this make a difference in us seeing simultaneous events?
|
askscience
|
http://www.reddit.com/r/askscience/comments/1c6zuj/having_trouble_understanding_relativity_and_time/
|
{
"a_id": [
"c9dn31b"
],
"score": [
4
],
"text": [
"I'm not an expert but I saw [this a while back](_URL_0_). I think that it will answer your question."
]
}
|
[] |
[] |
[
[
"http://youtu.be/kGsbBw1I0Rg"
]
] |
|
5yh3rv
|
why was prohibition less successful than the war on drugs?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/5yh3rv/eli5_why_was_prohibition_less_successful_than_the/
|
{
"a_id": [
"depy4ro",
"depy5vo",
"deq0ouh",
"deq1un4"
],
"score": [
13,
6,
5,
2
],
"text": [
"The war on drugs was a failure in the exact same way that prohibition of alcohol was. We just keep doing it anyway.",
"The percentage of people who use alcohol is higher than the amount that use drugs. The more people that flaunt the law, the harder it is to enforce.",
"It depends on how you define success. Context is super important. People often have different definitions, especially the ones who support or oppose it. \n\n[Here's a great chart on how the spending on enforcing the war on drugs has ballooned, yet we still have the same number of people addicted to drugs.](_URL_3_)\n\nIt always baffles me how a handful of people try to control the decisions of legal adults - especially because using drugs is a victimless crime. One things for certain - we now have several gigantic industries who are utterly dependent on ILLEGAL drugs to keep profits up.\n\n- Prison industry. 30 million people have been incarcerated on drug-related crimes. In the mid 2000's as much as 50% (well over a million people) of the prison population was in for drugs. One must also ask themselves... how successful are people at getting jobs after they get out of prison with a felony drug charge? [The private prison industry made $3.3 Billion in 2015](_URL_0_). In addition, [Of the 1,488,707 arrests for drug law violations in 2015, 83.9% (1,249,025) were for possession of a controlled substance. Only 16.1% (239,682) were for the sale or manufacturing of a drug.](_URL_1_)\n\n- Police Forces. [Between 2002-2012, over 1 million police hours were spent in New York City alone for simple marijuana possession.](_URL_2_) That's 50 full-time police officers for 10 years. Doing some simple math, about 1/40 people live in NYC - 50x40 = 2,000 officers over 10 years in the United States. That's just VERY SIMPLE marijuana charges. Add in crack, cocaine, heroine, etc and you can see where this goes.\n\nI stopped doing work to research this so I'm just going to summarize some other stuff...\n\n- Weapons manufacturers. The police force has been militarized / DEA.\n\n- Alcohol industry. Stands to lose A TON from legal marijuana if marijuana/alcohol are replacements.\n\n- Sheer number of probation officers and corrections officers.",
"Alcohol use had broad, mainstream support, especially among middle class whites.\n\nWith other drugs, it was easier to marginalize users as poor and criminal, especially if they were not white.\n\nThat said, by any reasonable assessment, the war on drugs has been an abject failure."
]
}
|
[] |
[] |
[
[],
[],
[
"https://www.washingtonpost.com/posteverything/wp/2015/04/28/how-for-profit-prisons-have-become-the-biggest-lobby-no-one-is-talking-about/?utm_term=.b20f23d627f0",
"http://www.drugwarfacts.org/cms/Crime#sthash.H1lG7UCG.dpuf",
"http://www.drugpolicy.org/sites/default/files/One_Million_Police_Hours.pdf",
"https://www.theatlantic.com/national/archive/2012/10/chart-says-war-drugs-isnt-working/322592/"
],
[]
] |
||
p3xei
|
elim5 why eating 5-6 smaller meals a day is better then 2-3?
|
Been in the workout and diet routine for a month now and this advice is always inconsistent. What gives?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/p3xei/elim5_why_eating_56_smaller_meals_a_day_is_better/
|
{
"a_id": [
"c3mamuu",
"c3maqkz",
"c3mbc6m",
"c3mcqky",
"c3mcug4"
],
"score": [
2,
2,
3,
4,
7
],
"text": [
"Nothing is \"better\" except whatever makes you the most comfortable. I like to eat less, but more often, because I feel better when I do. But I know this isn't true of everyone.\n",
"It's inconsistent because the science backing this claim up is pretty shaky at best. You lose weight if your body burns calories in excess of what it takes in, plain and simple. Diets act to comfortably facilitate this. If I am trying to cut weight, I find it easier to pig out once a day rather than eat smaller meals intermittently.",
"Supposedly, it's because it psychologically makes it easier to control portions. Nutrition is unaffected, and evidence even for the psychological effect is sketchy at best.",
"Its a myth from what I've heard. Some people think it will keep your metabolism running at peak performance for longer periods of time, but I remember reading studies a while back that said that that actually isn't the case. ",
"It isn't necessarily better. What matters is your overall caloric intake, be that in one meal daily or ten.\n\nThe idea behind eating more meals is that you never really get that hungry, so you don't overeat.\n\n\n"
]
}
|
[] |
[] |
[
[],
[],
[],
[],
[]
] |
|
9kp7op
|
if the voyager 1, the furthest man made object from earth, is roughly 18.8b km away, how do we know about cosmic webs, 100 billion lightyears away, and other extremely far structures of the universe?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/9kp7op/eli5_if_the_voyager_1_the_furthest_man_made/
|
{
"a_id": [
"e70pzel",
"e70q1nx"
],
"score": [
38,
3
],
"text": [
"We... look. \n\nWith telescopes. \n\nAnd mathematical calculations using the redshift of distant objects and the parallax of less distant objects as Earth orbits the Sun allow us to convert the 2D images produced by telescopes into 3D maps of the structure of the universe, lots of complexity to dive into there, but mostly we just use the fact that light has had nearly 14 billion years to get here from distant parts of the universe and... look at it. \n\nEdit: I should mention that we're quite uniquely lucky to be able to do this. A hundred billion years from now, only the faintest stars will still remain and the light from them will have been redshifted into near undetectability as the expansion of the universe accelerates, and ten billion years ago not enough light had reached a single point to get a good idea about the shape of the universe. \n\nEdit2: we don't know about *anything* more than 45 billion lightyears away. That's the furthest any information can have travelled relative to the object it came from since the Big Bang, even with expansion helping it. For all we know, pi is 4 50 billion lightyears from here. ",
"We know about them because they emit electromagnetic radiation or they absorb/bend radiation from other objects. That being said, because nothing travels faster than light, we only have information about the state they were in at the time they radiated. So if you're seeing objects that are a milion lightyears away, you see them as they were a milion years ago. So some of the stars that are shining on your night sky might not even exist now."
]
}
|
[] |
[] |
[
[],
[]
] |
||
o2qg9
|
In addition to the moon's own gravitational pull, do the tides it produces have any significant effect on my weight? i.e. is there a noticeable difference between high and low tides?
|
I've seen other posts asking "how much does the moon affect my weight" but the questions (and answers) seem to only address the gravitational pull of the moon itself due to its mass alone.
But what about all of the water sloshing around due to tides? Wikipedia tells me that there is 1,338,000,000 km^3 of water on this planet, and 97% of it is in oceans. I realize that only a small percentage of this moves around with the tides, but still that water is waaaaaaay closer than the moon is.
So I'm curious if all of that water has any significant gravitational pull of its own, and how a person's weight measurement might be affected between high and low tide. Any redditors out there with the requisite math skills to tackle this?
Feel free to assume I'm at the equator or north pole or anything else that makes your calculations easier.
And thanks!
|
askscience
|
http://www.reddit.com/r/askscience/comments/o2qg9/in_addition_to_the_moons_own_gravitational_pull/
|
{
"a_id": [
"c3dxbaw"
],
"score": [
6
],
"text": [
"It will have (little to) no effect on your weight, but it will change the vector of your weight ever so slightly. If this seems odd realize weight is simply the force of gravity upon your person and that force is a vector. All that mass is still acting on you just from different directions. If you want to define weight as the force of gravity towards the center of an object we can do a little math to see how much that water affects your weight.\n\nAssuming STP 1 cm^3 is 1 gram of mass for water. So we have 1km^3 is 10^12 kg of water. We have 1.338*10^21 kg of water on earth. The earth has a mass of 5.9736×10^24kg. The percent of the earth that is water by mass is then : .02% which is a gravitational acceleration of .21. using the % and a generic mass of say 70 kg if all the water disappeared you would lose 1.4 kg or about 3lbs. \n\nIf the water were to instead shift so that it was all on one side of the earth it would be at about 45 degrees to you only loose 2^(1/2)/2 or .7 of that mass with respect to \"down\". So in an extreme state a person of about 70 kg would loose about 1kg or 1.4% of their weight towards the center of the earth.\n\nNow considering the water on earth changes very very slightly in comparison to that while you do have a weight change (by either definition) it is very slight. A large part of this comes down to the mass of water being only a small part of the mass of Earth."
]
}
|
[] |
[] |
[
[]
] |
|
ci4pl3
|
What preservation are we doing today, that will make the lives of future historians far easier?
|
Are there records being kept day to day about events, weather, historic figures deaths, etc? And how will these records be retrievable in, say, 200-400 years?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/ci4pl3/what_preservation_are_we_doing_today_that_will/
|
{
"a_id": [
"ev1g2fj"
],
"score": [
3
],
"text": [
"The phasing out of teaching cursive in North America is going to mean that much sooner than 200 years the future, historians will need special training in paleography to read handwritten primary sources in their native languages. \n\n\nThere is no way to predict anything about 200 years in the future, however, among the concerns in preservation is the relationship between the material (eg. actual pieces of paper) and the digital Both are vulnerable to various sources of potential destruction. Paper can get destroyed. So can harddrives. It already difficult for historians to retrieve historical data that was preserved on things like floppy drives and CDroms. Any information that requires technology to access it means that you don't just need to preserve the data, you need to preserve the technology that uses it. \n\n\nTo wrap your head around this, you might want to look into the history of something like \"microfilm\". Even when a historian is grateful that the material got preserved (especially if originals were destroyed), working with the outdated technology feels miserable. There are similar complaints about the quality of other digital projects: such as Google Books scanning with hands on pages and failing to fold out pages necessary to see images."
]
}
|
[] |
[] |
[
[]
] |
|
3gxh48
|
why is it that when people film phone video in portrait mode common websites or apps like youtube, liveleak etc. don't allow play back automatically in portrait full screen mode?
|
These sites always shrink the video down into landscape view and thus its very tiny. If it was originally filmed full screen on a phone why can't I watch it back full screen on mine!?!
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/3gxh48/eli5_why_is_it_that_when_people_film_phone_video/
|
{
"a_id": [
"cu2fhr0"
],
"score": [
3
],
"text": [
"First off, you should never, ever, ever, record video in portrait. The only exception is with Intsagram and Vine, where they are 1:1, so it doesn't matter.\n \nIt's not filmed in \"full screen\" you filmed it sideways and the video player automatically rotates it for easy viewing, making it 9x16. YouTube cannot detect if a video should be displayed in portrait, because where would you draw the line? Letterboxed 4:3 should be horizontal for instance. \n \nWhat YouTube could do is, just like the browser's media player, allow all videos to be played in portrait and landscape, as for why they don't, no real reason other than that you shouldn't record video that way, the YouTube Capture app doesn't even allow portrait video to be recorded."
]
}
|
[] |
[] |
[
[]
] |
|
cj652z
|
Objective USSR history books which are based on the new sources that are available to us today?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/cj652z/objective_ussr_history_books_which_are_based_on/
|
{
"a_id": [
"evbqh3b"
],
"score": [
3
],
"text": [
"The mods of this sub have a pretty comprehensive [booklist](_URL_0_), it's unfortunately a little bare concerning glorious Soviet Union.\n\nI can personally recommend American historian Stephen Kotkin's series on Iosef Stalin (he's published two of the three planned parts thus far), *Paradoxes of Power 1878-1928*, and *Waiting for Hitler 1929-1941*. Both are well over 500 pages each and Kotkin explicitly explores much of the Soviet Union beyond its leader of the time with the idea that Stalin is a historical figure and as such needs to be understood in the context of the places he lived and the events occurring in the world around him. He used a number of sources from archives which are not open to western historians (i.e. because they are accessible only to certain citizens of the Russian Federation) such as the NKVD archives in the Perm Krai region of western Siberia. In presentations and lectures on the book I have seen him claim that he has friends in Russian academia who passed him sources he requested, which doesn't seem altogether improbable to me.\n\nRobert Service has written a great number of books concerning the Soviet Union, many of them since formerly closed Soviet archives were opened to the public. Personally, I really enjoyed his biography of Trotsky (2009), *Comrades: A World History of Communism (2007)*, and *The End of the Cold War 1985-1991* (2015)."
]
}
|
[] |
[] |
[
[
"https://www.reddit.com/r/AskHistorians/wiki/books/coldwar#wiki_europe_and_russia"
]
] |
||
23wl4a
|
Are there any sounds that the alphabets can not spell?
|
askscience
|
http://www.reddit.com/r/askscience/comments/23wl4a/are_there_any_sounds_that_the_alphabets_can_not/
|
{
"a_id": [
"ch19vi7"
],
"score": [
16
],
"text": [
"Define \"alphabets\". %-)\n\nThere are a **lot** of languages in the world (over 4000), and among them they cover a **huge** range of different sounds or phonemes, including sounds we Anglophones wouldn't think of as \"sounds you could use in words\"; clicks, for example, or really difficult sounds like the one rendered in the Czech language as ř.\n\nLinguists mostly use something called the International Phonetic Alphabet (IPA) to render sounds and phonemes from any language, or even any dialect or accent of any language. Most of the characters in the IPA are derived from the Roman alphabet (A,B,C,D...), some from the Greek (A,B,Γ,Δ...), and some were just plain invented.\n\nIPA includes over 100 \"letters\", more than 50 diacritical marks, and a few other odds and sods. There are also \"Extensions to the IPA\", which include 30-40 more symbols to handle sounds like smacking lips, gnashing teeth, or the snoring-like sound made by some people with cleft palates.\n\nIf there are any languages out there that may have a sound or sounds that the IPA doesn't cover, we probably haven't found that language yet.\n\nFor an intro to IPA, you could do worse than [the Wikipedia article.](_URL_0_) IPA is managed by [IPA, the International Phonetic Association.](_URL_1_)"
]
}
|
[] |
[] |
[
[
"http://en.wikipedia.org/wiki/International_Phonetic_Alphabet",
"http://www.langsci.ucl.ac.uk/ipa/"
]
] |
||
4cm2rq
|
why does burping through the nose not smell as bad as through the mouth?
|
[deleted]
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/4cm2rq/eli5_why_does_burping_through_the_nose_not_smell/
|
{
"a_id": [
"d1je5ot"
],
"score": [
2
],
"text": [
"Air going out of the mouth will include any of the smells that cause bad breath caused by bacteria living in your mouth (which are rather happy after you've just eaten). When air goes out through the nose, it doesn't pick these smells up."
]
}
|
[] |
[] |
[
[]
] |
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