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What is the difference between a motif and a theme? | [
"If I recall correctly, a motif is usually a recurring plot device, while a theme is more of \"the point\" of the work. A motif is usually an object or item that represents the theme of the medium, while the theme is more of an idea about what the author was trying to convey."
] | [
"Salt & Pepper season our food. They make it taste better. Spices & Herbs flavor our food. They make it taste different. Season everything. source: Chef."
] |
why do yellow jackets (wasps) tend to hang out around metals such as bleachers or cars? | [
"An educated guess would be that it doesn't have to do with the metal, but whats around the metal. Bleachers are usually used for sporting events so there are lots of sweets around (spilled soda/dropped candy) and cars usually have the remains of smashed insects on them. So wasps just wanna eat and those are places with lots of meals."
] | [
"The University of Florida [Honey Bee Lab](_URL_1_) has grad students working on native bee research and website that [includes instructions on building nest sites](_URL_0_) for North American Bees. I'm sure they can answer questions directly about species attracted. But in short most solitary bees that nest in tubes just look for one the right diameter and length. This is why the sample nest site has lots of different size tubes so you are bound to attract whatever is native to your area."
] |
why do some countries have such large currency bills? | [
"Inflation. Let's put it this way, in America it used to be that you could buy a steak dinner for let's say $5. Then today that same steak dinner would cost $50. How much we pay for things, and how much we get paid has increased slowly over time. In other countries, it has increased way faster, so something that used to cost $5 might now cost $5000. Everyone's getting paid more to compensate, but it's still so fast that you have to keep adding more and more to your currency to compensate. Some countries just redefine their currency to make it easier, stating that $1 new dollar is worth $10,000 old dollars for instance. Others just deal with it until their economies collapse."
] | [
"When you take a pill it's not 100% the labeled medication. There are other ingredients that help it do its job and release when and how it is supposed to. Sometimes a medicine needs more extra ingredients to do its job so you end up with a bigger pill."
] |
What triggers the explosions of atomic and hydrogen bombs? | [
"When you get a large enough chunk of certain radioactive materials together, it explodes. In a bomb, two pieces of material, each too small to explode, are kept separate. A small conventional explosive pushes them together, forming a chunk long enough to sustain a nuclear reaction and setting off the full explosion. (This is one design, of several, but that's the basic idea)"
] | [
"It's similar to the principles behind a volcano. Pressure keeps building up and building up in one specific point. However, there is some strong material resisting that pressure, in the volcano case it is the dirt, rock, and metal sitting above it, and in the book case it's the pages sitting under the press. However, the moment the object exerted more pressure than the material can resist (the magma in the volcano and the press in the video), *all* the pressure is *immediately* released. So, the stronger the material's ability to resist the pressure, the stronger the eventual detonation eventually is. That is why some \"volcanoes\" just regular spit out lava, and other times [they detonate so hard that half the volcano is destroyed in the process](_URL_0_)."
] |
Why is the Euro collapsing? It seems like such a good idea for all of Europe to share a currency. | [
"A single currency allows for more efficient trade, but removes monetary policy from the individual nations and gives it to the bank of the entire EuroZone. As everyone is using and borrowing the same currency, when some countries *cough Greece cough* lie about their finances to get in and then do a terrible job on their own economy, it hurts their currency which is also the currency of everyone else in the Eurozone. This makes it harder for other countries to borrow money, which hurts their economies, and makes it even HARDER for the others (and those initial countries) to borrow money, etc. etc."
] | [
"If you have a spare afternoon or two I'd check out these two Khan Academy playlists on the [Credit Crisis](_URL_2_) and the [Paulson Bailout](_URL_0_), and if you want to learn more about how banks work check out this [Banking and Money](_URL_1_) playlist as well; there's a few others on finance and credit as well if you want to look for them."
] |
If cellphones are replacing landlines, why aren't there versions of white pages for cellphones? How are landlines any different? | [
"Problem Is there are multiple cell phone companies, so if each had their own book it would be incomplete and inconvenient to have to look through 5 books to find a person. Land lines used to be one company in an area generally. It was a weird deal because they were a company, but a utility and basically a monopoly. Even after it was deregulated it still stayed much the same. And even if someone does somehow arrange to get one combined cell list, it's still going to be very incomplete because people could choose to be unlisted and a large percentage would. I know I would."
] | [
"Cost. Solar panels are still more expensive to make and install vs. tapping into existing infrastructure. Also, anywhere without good sun exposure will get crappy use from solar panels. The need for a second, backup source of power for extended periods of time would, effectively, make it cost more to do solar than to just tap into the grid in the first place."
] |
Why is getting sleep/rest good for your body, but sitting down/relaxing at your desk during a workday considered to damage your body and put you at risk for a heart attack? | [
"It's the sleep part that's good for you, not the laying there motionless part. Sleeping all day is just as bad for your body as sitting at a desk all day, (although it'd probably be a lot easier on your back)."
] | [
"It's better to be facing backwards (this applies in planes as well). Either way, you're basically going to be decelerating instantaneously. The difference is where the force is applied. When facing backwards, the force is distributed across your entire back and it keeps all of your body parts held in stable positions. When facing forwards, assuming you aren't strapped in in any way, it's much more likely that your initial impact would be on a very small area, such as your face, the top of your head, or a limb. Even if you were to be strapped in, the force is being distributed over a much smaller area than if you're facing backwards, and your head would also snap forward (and likely back again), causing whiplash, a concussion, or worse. Edit: The primary reason that plane seats are oriented towards the front is just because passengers prefer that. Plane accidents are rare enough that this sort of thing isn't a big enough issue to attract public attention, but perceived discomfort is."
] |
How does imagination work | [
"really it's just electrical impulses in your brain. imagination is basically thoughts/ideas in a fluid recognizable format for you in your mind's eye. personal experience"
] | [
"How do you know you are perfectly recreating a sound in your head? Your head tells you it is."
] |
Why do we feel sadness and what is the root cause of it? | [
"We don't really know why emotions make us feel certain ways, but we do know what causes the specific feelings. Your brain considers physical sensations and sensations caused by your mind to be the same thing. We don't know why it works this way, but it does. Since sadness is mental pain, the brain treats it similar (but not identical) to physical pain, and releases lots of fun hormones to help you responds to it. I suppose you could say the root cause really is that the way we feel things was at some point extremely important to the survival of species that would eventually give rise to humanity."
] | [
"The rods and cones in your eye (the vision receptor cells) only contain a finite amount of rhodopsin (the chemical that absoarbs light). After it absoarbs enough light, the chemical needs to be recycled, which takes some minutes. Until that time, those cells can no longer detect light or \"see\"... thus according to all those cells they report to your brain as seeing darkness."
] |
When did the colors red and blue become indicative of their respective political parties? | [
"In the United States, the year 2000. The color representing each political party used to switch back and forth, but during the controversial election of 2000 the election maps were so closely scrutinized that it became engraved in the public conscious that blue represented the democratic party, and red the republican. This color scheme is somewhat ironic considering that in most other parts of the world, red is typically associated with ~~liberal~~ leftist parties and blue with conservative ones."
] | [
"I feel like this question is a bit outside of this subreddit's scope, it's really more of an economics question, plus if you look at [this graph](_URL_0_) then you can see that they were at very similar levels until around 20 years ago when they diverged, so anything following that violates the subreddits 20 year rule. I'd recommend at least crossposting to /r/AskSocialScience"
] |
what’s the difference between aged cheese and old cheese? | [
"Aged cheeses are kept at very specific temperature and humidity. They are also, depending on the style, turned and wiped/brushed often. The cheese will age slowly and not go bad as the cheese maker closely monitors for any evidence of runaway molds. Sometimes even a properly attended to wheel will still get infected and go bad. Source: I make cheese and my family has been making cheeses for the past hundred years."
] | [
"From our standpoint as users, nothing at all. From Reddit's standpoint, one of them means the backend computers told them \"sorry too busy\" and the other means that the backend didn't respond at all."
] |
Why is katsaridaphobia (fear of cockroaches) so common? | [
"Because they are miniature lovecraftian hellbeasts! I almost broke my ankle \"teleporting\" over the couch to get away from a palmetto bug (cockroaches bigger, uglier, even harder to kill cousin in the south) once. They are made of malice and hatred of people and will fly in your face for no damn reason. I tried to kill one once, \"kill it with Raid\" my husband said, \"It will die instantly\" he said reassuringly (from a safe distance over the phone)...it flew into my EYE covered in raid and then escaped. I was blind for like and hour and it got away scott free. Why are we afraid of roaches...because they are scary and have evil murderous hearts that won't quit beating until they have filled you with the maximum amount of rage-panic!! Ok, rant over."
] | [
"One thing to realize is that the population density was much lower. If we take all of kansas as an example, only a few of the thousands of towns have been really devastated by tornadoes in the last generation. Thus if we take that whole area of kansas and assume a similar rate of large tornados, then the odds of any single generation or community dealing with severe destruction is rather low. Edit: this really shouldn't be the top comment, I wasn't attempting to answer OP's question completely, just making one small point."
] |
What is the difference b/w Bounce and EDM? | [
"EDM is not a genre, EDM covers everything. From time to time, some record company will try to push some sub-genre as \"EDM\" (or, in the dark days, just call it all \"techno\") but that's generally just going to be generic, commercially accessible variety of stuff. As for \"bounce\", that was an old-school thing from the South that was more closely related to hip-hop than the EDM scene. I wouldn't really be surprised if somebody's recycled the name for a modern neo-bounce thing. EDM genres & sub-genres change all the time & fragment so it's impossible to keep up. If you get distracted for a year or two, you'll just be completely out of the loop and have no idea what's going on anymore."
] | [
"Royalties must be paid to you every time something sells, even if the business isn't making a profit. Equity means you own part of the company, which is only useful if the company itself is profitable or valuable."
] |
Why are flames pointy? | [
"A flame rises because it is warmer than the air around it. The cool air rushes in to push the hot air upwards. However, as the air rises it also cools down. It cools down from the outside inwards. A flame glows because it is hot enough to generate light. So as the flame cools down, the parts of it that are hot enough to generate light get smaller and smaller. Because it is rising and shrinking at the same time, it forms that pointy shape. Note that a flame in zero gravity doesn't make a pointy shape, because the cool air doesn't push the hot air upwards (because there is no up). It just spreads out in all directions."
] | [
"These bonds show the 3 dimensional structure of the molecule. The plain lines are in the plane of the page. The solid wedge shape signifies a bond coming out of the page towards you. The dashed line signifies a bond going into the page away from you. It's as simple as that. Chemists use this to show a 3D structure in a 2D drawing."
] |
Why is it dangerous to wake up a person who is sleep walking? | [
"It isn't, particularly. That's a myth. Though it can be extremely disorienting for the person concerned, and they might become very agitated. But it's not a danger to their health or some such."
] | [
"Same reason you don't keep turning the ignition key for hours in your car when it won't start -- there's no point in doing it, it won't get better."
] |
What makes a river like the Mississippi change course? | [
"A new flow does not have to be more efficient totally. Is only have to be locally easier to flow in a direction. A river can start to [meander](_URL_0_). The only thing that has to happen is that the water flow faster on one side then the other. Then sediment will be deposited on the slower side and removed on the faster so the path of the river will move. If the meander is large the river can intersect in own path downstream and a [Oxbow lake](_URL_1_) is formed where the river no longer flow. So a river change course not by a sudden clogging of the old path but by a slow move of its path. There can be a sudden change if the land in not even and the river eroderad away natural dam and flow down to a lower land area"
] | [
"Because there isn't any \"adapting\" to a runaway greenhouse effect feedback loop. Without care, we could turn Earth into another Venus. Most of the \"finger pointing\" is being done because *some* people try to deny mankind's influence on the climate and use that as an excuse to take no responsibility and not make changes in order to help stop the problem before it becomes completely irreversible."
] |
Do neutrons bound to stable atoms decay the same way protons do over long timescales? | [
"A nucleus containing protons and neutrons fills two sets of quantum states, one for neutrons and one for protons. You then calculate the total energy for that configuration. Now you check what would happen to the energy if you fill the same quantum states with one more proton and one less neutron, plus an electron and an (anti-) neutrino. If the total energy is less than what you originally had, one neutron will beta decay to a proton. It is the total energy of the system that decides if the system is stable or not, not the properties of the individual constituent particles."
] | [
"> because each flavor has a different mass The flavors don’t have well-defined masses. There are three mass eigenstates and three flavor eigenstates. But a neutrino or a given mass is a superposition of all three flavors, and a neutrino of a given flavor is a superposition of all three masses. If the flavors had different, well-defined masses, they wouldn’t oscillate. As for why the wave packet doesn’t spread out, actually it does a little bit. If the neutrino has a given energy, the group velocities of the different mass eigenstates are different. But since the neutrino masses are so small, neutrinos are usually always moving at approximately c anyway."
] |
Is there a maximum velocity (besides the speed of light) to which a space probe could be accelerated using repeated gravity assists within our solar system? | [
"Once you're moving at greater than solar escape velocity (which varies with distance from the sun but near Earth is 42 km/s, compared to Earth's orbital velocity of 30 km/s) then after each assist you have to be on a path to pass another body for your next assist or else you'll just shoot out of the solar system. The higher your velocity, the less you can alter your trajectory with a gravity assist, so the exact answer to this question will depend strongly on the current geometry of the planets."
] | [
"If you go out first, you shoot the rocket fuel backwards, reducing its kinetic energy (in the reference frame of the Sun) while increasing your energy. You hit the Sun with a higher energy. If you go inwards directly, you shoot the rocket fuel forwards, increasing its kinetic energy (in the reference frame of the Sun) while decreasing your energy. You hit the Sun with a lower energy. If you sum over all energies then this sum is always constant - just don't forget the rocket fuel in the sum."
] |
Why does the moon appear smaller in pictures than "real life." | [
"In pictures, most of the time it's just because it's zoomed in, the lens has a different focal length than your eye. Your view of the same scene is going to be much, much wider. The moon is generally only about the size of a pea held at arm's length. There is a real-world correlation to this, though, which is that (for some reason) people estimate that the moon is 50-75% larger when it's on the horizon vs when it's high in the sky."
] | [
"It isn't a matter of scale, but rather your eyes' focal point. Even if a big screen and a phone held up close are equivalent, there is still a difference between focusing your eyes several inches in front of you versus 50 feet away. ETA: I might answering LI6, so someone with more knowledge please come in and help me."
] |
Can extreme tidal forces have an effect on the half life of an atom? | [
"In principle: yes. In practice: well... A very rough estimate: Tidal gravity scales with GM/r^(3), the alpha nucleus would need to see something like 1 MeV/fm force over a distance of 1 fm. We get relevant tidal forces if GMm/r^3 = 1 MeV/fm^(2) where m is the mass of the alpha particle. The closest stable orbit around a non-rotating black hole happens at 3 times the Schwarzschild radius, or r=6 GM/c^(2). Plugging that in, we get M = sqrt(c^6 m/(1 MeV/fm^2 G^(2))), roughly [10^15 kg](_URL_0_)+(gravitational+constant\\)%5E2\\)\\)). The corresponding Schwarzschild radius is just 4000 fm. Large enough to have nuclei orbiting it, it might work, although the range of possible black hole masses is quite narrow. Smaller black holes work as well but at some point the orbits don't get well-defined any more. It is unknown if there are black holes smaller than a few solar masses."
] | [
"Nop, no correlation has been found. _URL_0_ > Several extensive literature reviews and meta-analyses have found no correlation between the lunar cycle and human biology or behavior.[1][2][3][4] One study with strong experimental controls indicates a possible connection between sleep quality and lunar phases,[5] but there has been no independent confirmation of these results to date."
] |
Why carbonated drinks taste bad once they're flat | [
"When you carbonate a drink the CO2 dissolves into carbonic acid, carbonic acid is sour (it's an acid which are generally sour). When they go flat the sour flavour goes with the CO2. It taste bad because it's missing an ingredient that adds flavor. Many sodas are also very sweet, and are not palatable without some sourness to offset the sweetness (sweet and sour go together, take out the carbonic acid and you get just sugar water which is way too sweet)."
] | [
"It's about novelty. When it's new, we cherish it and want to take care of it. Novelty eventually becomes familiarity. We see this a lot with cars. That new car, the owner is so careful. At some point, however, it becomes OK to toss that empty Big Mac box in the back seat."
] |
The Communist Manifesto and why it was so influential. | [
"I just would add that the Communist Manifesto was also important for its influence in capitalist countries, ie, Bismarck's passing of social safety net laws to undermine Socialist platforms in Germany."
] | [
"I have a question for you. Do you want the version that is super, super long and includes a write-up on what actually went down at Munich, and the subsequent responses back and forth? Or do you want the shorter version that only talks about media coverage of the incident and how it changed things?"
] |
Why do Bosnians, Croatians, and Serbians seem to hate each other? | [
"Croatia is Catholic, Serbia is Orthodox and Bosnia has both as well as a large Muslim population. This is a reason for age-old tensions. They used to all be one country called Yugoslavia. It broke up in the early 90s and violence occurred. Serbia was involved in wars with Croatia as well as war and genocides against Bosnian and Kosovar Muslims. Kosovo is majority Muslim independent country south of Serbia, however its independence is not recognised by many countries including Serbia, another source of tension."
] | [
"It's a good ghost story, in the typical version - \"Settlement vanishes, the only clue is the mysterious word CROATOAN carved into a fencepost\". It's not much of a mystery to people who have done research on the area, though. The Roanoke colony was friendly with the local Indians, who had a settlement on the nearby island called Croatoan. Nobody ever got around to checking if they moved there, but reports from other settlers in the area mentions that tribe of indians had white members, built two-story stone houses, and spent the next hundred years telling people they had white ancestors, and showing off their European eye colors. And archaeological digs on the island have found European artifacts. \"They moved\" is just a much less interesting story than \"they mysteriously vanished ooOOOooooOOO\"."
] |
How much energy is in water? | [
"If by energy you mean energy that the human body produces from food, then 0. H2O (along with CO2) is the chemical output of the body metabolizing food. The body does not process water to produce energy."
] | [
"using \"exothermic\" chemistery \\(reactions that release heat\\) and by muscle movement \\(which again uses up a lot of molecules in exothermic reactions as well as friction between the muscle cells during movement\\) Energy is usually stored as fat. Fat gets converted back into glucose which your body can use to get \"Adenintriphosphate\" \\(short ATP\\). Your body then can use that molecule for energy delivery by transforming the TRIphosphate into a DIphosphate \\(ADP\\) which again is a very energy rich, exothermic reaction."
] |
Why don't cleaner fish get infected by parasites from the fish they help to clean? | [
"Cleaner fish remove ectoparasites, which live exclusively outside of the body. Once the cleaner fish ingest them they aren't able to parasitize internally. Endoparasites would be able to though."
] | [
"One factor concerning salinity is [osmotic pressure](_URL_2_). When the internal salt concentration of a cell is higher than the environment, the cell must have mechanisms to relieve this pressure, else it will swell and burst. [While there are some bacteria that can survive just fine in pure water, the osmotic stress from seawater is lower than that from fresh water](_URL_4_), making seawater \"easier\" for cells in terms of osmotic stress. In fact, [salinity is one of the major determinants of biodiversity](_URL_3_). Another factor is sunlight. The cornerstone of both freshwater and salt water ecosystems are photosynthesizers, and [this can take place at depths of up to 200 meters](_URL_0_). This referred to as the [photic zone](_URL_1_). Although plenty of freshwater systems can reach this depth, on the average freshwater systems are shallower than salt water systems, and thus can support less biomass overall."
] |
Is it possible for a four legged winged animal to have existed? | [
"I remember seeing a video of a golden eagle flying with a goat it had picked up. So it seems like it's possible for a four-legged animal to be kept airborne with wings."
] | [
"Xenotransfusion has been attempted in the 1600s, with mixed results, with sheep blood. Ape and chimp blood might work, as would pig blood as they all have similar Rh factors. Source: _URL_0_ Also, dog to cat transfusions can be done, bit only once as the cat will make antibodies to the blood. Also, apes, dogs, cats, and birds all have blood types."
] |
How can a tiny $399 Go Pro with small battery shoot in 4K 60fps where as the large and bulky $2000 prosumer camcorders that also eat up power bricks of energy from companies like Sony only do 4K 30fps? | [
"4k describes the number of pixels the camera is capturing but there are other factors like color depth that describe how many shades of color the camera is capturing. The Hero 7 can record a bitrate of up to 78 Mb/s. Prosumer cameras can record up to 400 Mb/s. So the GoPro is sacrificing color and quality of the image to get a higher frame rate. I'll also add that Prosumer cameras can do 4k at 60fps these days, at a higher bitrate than the GoPro."
] | [
"How to train a dragon took 90 Million CPU hours to render (_URL_2_). They used HP servers.(_URL_0_) Big Hero 6 (199 Million Core Hours). The render farm used on this production was able to produce 1.1 Million core hours a day. (_URL_1_). I am guessing there are using 55,000 Intel Xeon Core Server farm to render that movie. I would boil that down to 200 days on a super expensive render farm/cloud to make current AAA animated movie."
] |
When an impact object (like shown in the video in the text) hits water at an angle why does the water column shoot vertically upward and not at an angle? | [
"Well in this case, the object is hitting the water at a tremendous velocity. Upon impact the water around the area is instantly vapourized and creates essentially an explosion just under the surface of the water. This explosion is almost entirely what is responsible for the resulting water column, and is spherical, thus resulting in a vertical water column. If you did this same thing at low velocity you would, as in when you throw a rock into a pond at a low angle, see that in fact the water tends to splash mostly in the direction the rock was moving."
] | [
"This doesn't change between babies and adults. It's actually the exact same. What changes is they way we take our drinks as we get older. As babies we are drinking from a nipple (either an actual nipple of a simulated one on baby bottles). A baby has to suck to get liquid out of it. If you tilt a baby bottle, very little will come out until the baby starts sucking on it. This allows the baby to control the amount of fluid going into their mouth. As adults we are drinking from cups or glasses. In this situation, the tilt on the cup/glass decides how much fluid is going into your mouth. If we lay down, it's very hard to control how much liquid is going into our mouth so we may choke. Of course, if you were to drink out of a baby bottle, you would have no problem lying on your back."
] |
Why is the "head" on soda much shorter lived than on beer? | [
"Protein! Beer has residual proteins from the grains used to make the beer; these proteins give structural stability to the foam. Most (all?) sodas do not have any protein content to speak of, so there's nothing to stabilize the foam."
] | [
"This is called the [Cheerios Effect](_URL_1_). I find this amusing. Basically, when something is floating in a liquid, a [meniscus](_URL_0_) forms around it. (In the case of the bubbles, it's a concave meniscus.) Since the bubbles float, they want to be at the highest point achievable on the surface of the liquid, and since the meniscus around the bubbles is higher than the rest of the surface, the bubbles tend towards each other."
] |
How can animals like bears get wet and not freeze to death in the winter but if a human wearing fur clothes gets wet, they freeze easily? | [
"* Hairs retain dramatically less water than an insulated jacket * Said hairs often are covered with oils that further repel water So, while a bear may get wet, the fur's not going to get completely water-logged like a coat would."
] | [
"Atoms bonding together to make compounds fundamentally changes how those atoms as a combined entity behaves as opposed to how they behave separately. It all comes down to the strength of the interactions between atoms and molecules, and how many different ways these molecules can absorb heat energy. When oxygen and hydrogen are in gaseous form, they have weak interactions between their molecules so it doesn't take much energy to break these and free the molecules, forming a gas. In contrast, water has much stronger forces between molecules. This means it needs more energy for the molecules to be free. Secondly, water has more ways it can absorb heat - so-called *degrees of freedom*. It has two bonds which can stretch and vibrate in response to heat energy, in addition to the molecule as a whole being able to vibrate more. This means it can absorb a lot of heat before turning into gas, which is why it's liquid at room temperature."
] |
Drunk Americans today enjoy gorging on wings, pizza, and other bar/drunk foods. However, these foods are quite new. What did drunk Americans eat before deep fryers and pizza? | [
"You may want to x-post this over at /r/AskFoodHistorians"
] | [
"Well kid, you remember the difference between nouns, verbs and adjectives, right? And sometimes you can put \"that\" or \"also\" in a sentence or take it out and it doesn't change the meaning? Well, put those together and you have this sentence. Let's take something with the same structure. \"Dallas chickens that Dallas chickens fight also fight Dallas chickens\". It's a pretty meaningless sentence, but at least it's understandable. You can remove the \"that\" and the \"also\" and you get a sentence with the same meaning. \"Dallas chickens Dallas chickens fight fight Dallas chickens.\" Still with me? \"Buffalo\" has three meanings in this sentence. 1. \"Buffalo\", the town 2. \"buffalo\", the animal 3. \"buffalo\", the verb, meaning to bully Replace \"Dallas\" with \"Buffalo\", \"chicken\" with \"buffalo\", and \"fight\" with \"buffalo\", and you get \"Buffalo buffalo Buffalo buffalo buffalo buffalo Buffalo buffalo\". Go wash your hands."
] |
why does the point system in football count by 6 and not by just one? | [
"In American football, there are ways to score by two (safety), three (field goal), six (touchdown), seven (TD and extra point), and eight (TD with two-point conversion). So it would be pretty difficult to simplify the scoring while keeping the value of each action the same."
] | [
"Custom and practice. If you build it and it falls down, you do it again differently. When it works, you keep it like that. That, and people weren't stupid or uneducated - the Greeks were fairly capable mathematicians, as were the Egyptians"
] |
How could two different species, Neanderthals and Homo Sapiens evolve out of only one single species, the Homo Heidelbergensis ? | [
"Two sub populations diverged over time until they couldn't interbreed any longer. It's a very common thing over long enough time frames. Geographic isolation of part of the population means that any mutations arising within them don't end up outside that group, as they would if the entire species were free to mix. This can happen very easily in a species that is spreading out into new areas, for instance."
] | [
"Well, the House of Habsburg went extinct in the 1740s, with Maria Theresa as the last 'true' Habsburg. Her husband, Emperor Francis I, was of the House of Lorraine. The house resulting from their marriage was styled as the House of Habsburg-Lorraine, rather than simply remaining the House of Lorraine, and was often simply called the House of Habsburg. I'm not sure if this is what you were looking for, but it's the closest thing I could think of off the top of my head."
] |
I love Bronze Age history. Where can I learn more about it? I mean, what are the most comprehensible academic books on the matter? | [
"I'm a Belgian history student and the book our professor used for her lectures was 'A history of the ancient Near East, ca. 3000-323 bc. (Third Edition) By Marc Van De Mieroop. It probably isn't the most famous book on the subject, but it gives you a good overview of ancient Mesopotamia from 3000 bc until the arrival of Alexander the Great."
] | [
"Hi - we as mods have approved this thread, because while this is a homework question, it is asking for clarification or resources, rather than the answer itself, which is fine according to [our rules](_URL_1_). This policy is further explained in this [Rules Roundtable thread](_URL_3_) and this [META Thread](_URL_2_). As a result, we'd also like to remind potential answerers to follow our rules on homework - please make sure that your answers focus appropriately on clarifications and detailing the resources that OP could be using. Additionally, while users may be able to help you out with specifics relating to your question, we also have plenty of information on /r/AskHistorians on how to find and understand good sources in general. For instance, please check out our six-part series, \"[Finding and Understanding Sources](_URL_0_)\", which has a wealth of information that may be useful for finding and understanding information for your essay."
] |
Why does the world's economy only grow at 3% (aprox)? | [
"Believe it or not, by historical standards a 3% growth rate is actually very high. Economic growth is a massively complex phenomenon and there are a ton of factors that determine an economy's growth rate. In the simplest terms, economic growth is a result of people deciding to delay current consumption (i.e. people save some of their money). The money that is saved is used to invest in new capital goods (e.g. tools for workers, buildings and so on). Because an economy has more capital than before it can produce more than it did before and that's what we call economic growth. The rate of growth then depends on the savings rate as well as a ton of other factors such as: population growth rate, income distribution, standards of living. Hope that helps somewhat :)"
] | [
"You have a lemonade stand. You sell it for 50 cents a cup. One day you find out it's going to be very hot outside and people are going to want more lemonade. You figure you can get away with selling it for a little more since the demand is there. So you start charging 80 cents. You notice that the number of people paying for lemonade hasn't gone down. So because people are comfortable with the new price you decide you won't bring prices down even when it's not that hot anymore. Now replace lemonade stand with gasoline stations."
] |
Why can your body fight some infections itself (for example body-piercing infections) but needs antibiotics for others (such as urinary tract infections)? | [
"It depends on the severity of the infection. Some systemic (exposure to the bloodstream) infections cannot be fought alone, while some UTIs can resolve themselves. The main thing about UTIs is that unlike body piercings, which are supplied by blood vessels and thus can be easily reached by white blood cells (which allow the body to fight off the infection directly), the urinary tract provides almost no access for white blood cells to enter and fight off the infection, meaning that if the infection is severe enough to not be washed out by urination, it has no other means of fending off an infection. Antibiotics can enter the urinary tract by being dissolved into the urine, which allows them to kill the bacteria."
] | [
"If two pyrimidine bases occur next to each other on the DNA (TT, TC, CC), UV radiation can induce a chemical reaction in which they become covalently bound to one another (TT dimers are the most common, TC dimers are less common, and CC dimers are rare). These cause the double helix to assume a \"lumpy\" shape that prevents it from being bound by the proteins that drive repication and transcription. They can also be repaired by DNA repair enzymes in a way that introduces point mutations. A cell that accumulates enough of these modifications will eventually die. Any bacteria that's highly resistant to radiation, such as Deinococcus radiodurans, is likely to withstand UV treatment. Additionally, resistance to UV light can be selected within a population of susceptible bacteria through repeated sublethal doses of UV radiation with time for recovery in between."
] |
How do we know about dinosaurs soft tissue morphology through fossils? | [
"Bones change in shape throughout life. This can be in response to major trauma like a break, but it also occurs as a result of forces exerted on the bones by the muscles. Muscle attachment points that are put under greater tension grow larger and thicker. This is also the case for the walls of long bones near these attachment points. By examining these dimensions and comparing them to what we know from living species, we can estimate the amount of force exerted by a creature's muscles and from that their size."
] | [
"Based on the location of mountains and volcanos you can work out when plates are pushing together or moving apart. Based on the composition of rocks in different areas you can work out when two areas used to be close to each other but aren't now."
] |
Why have humans advanced in science, knowledge and technology so much and so fast in the last 150 years as compared with the last 5000 years? | [
"History is really just a hobby of mine (I'm a biologist) but I've heard one theory about this that seems to make sense. Apparently, though the Greeks and Romans had innovations that were advanced enough to have led to an industrial revolution, it didn't happen because they didn't need machines to do their work for them. Why? Because slavery. All of the large ancient cultures you mentioned had slaves to do their most menial and necessary tasks, so there was absolutely no incentive to come up with a machine to do those jobs. However, by the time the real Industrial Revolution happened, slavery was either completely illegal, or it was at least out of vogue in the locations where the innovations occurred so there was a real need to come up with ways to do difficult, tedious tasks more quickly and easily."
] | [
"Basically its the idea that Darwinism (natural selection and self pruning of undesirable traits through low suvivability) applies to brain neurons. Key part of it is that when you are born, your brain develops in a ton of diverse ways, just because. As you age, the brain goes \"This part's not needed\" and prunes that part off, so that things that are needed develop more. This is important because it differs from the view that we are born with a blank slate, and as we do things growing up, our brains build things in response to those ideas. Similar end result, different process."
] |
Why do phone cameras record video in verticle format by default when held in their normal position when a horizontal image is the default when watching any video? | [
"The camera sensor is rectangular. It does not rotate. So by holding the camera vertically you are also holding the sensor vertically. The camera *could* crop the video down to a lanscape orientation, but it will be at the cost of vastly reduced resolution (you're literally ignoring more than half the pixels on the sensor). Just hold the phone the right way around"
] | [
"YouTube changed how they pay youtubers to be based on how frequently they upload and the length of their videos. Let's plays, and other game play videos can be very long and don't take much time to make. Not saying they're bad, but these videos are so perfect in the eyes of YouTube they get paid more than basically anyone else. It may be cool to get a really high quality video, but those aren't profitable to YouTube and thus not as profitable to creators."
] |
Why do the videos I take on an iPhone look nice and clear on the phone but I upload them or send to another phone it's grainy and blurry? | [
"Because the video you send is not the same video you recorded. It's NOT about the transfer degrading the quality, it's about actual different files. I just did a test and recorded a very clear, nice-looking horizontal video on an iPhone, uploaded it in HD to YouTube and sent it to my Android. The iPhone version was in clear 1280x720 resolution on YT, but the version sent to my other phone looks so blurry and disgusting you can barely see what's going on. Basically Apple would rather force you to send terrible-quality video than give you the option to send the original, which isn't even that big. You can still get the high-quality video from the iPhone, it just has to be through some other channel. Maybe Dropbox?"
] | [
"Camera lenses collect and focus light onto the detector. As all the light needs to pass through the lens the quality of the final image is impacted by lens quality to a very large extent. Even the best camera can't salvage an image ruined by a crummy lens."
] |
The pros and cons of raising minimum wage | [
"I've heard people saying we need something like $15 minimum wage. My question is what are we going to do with the people who make $15/hour now? Many doctor offices are operated by staff at around that salary; wouldn't they expect a salary increase? Many technical jobs that require at least a two-year degree pay about $15, what would be the point of getting educated if flipping burgers now pays the same? Or think of labor unions who have enormous bargaining powers - they basically peg their salaries to minimum wage - non union grocery baggers now make twice as much? Guess that the unions will expect? ---- Natural outcome of increased minimum wage would be the expectation of increase in wage for many if not most professions. With across-the-board increases in salaries would come inflation that the govt has been trying to suppress with the Federal Reserve policies for years now. Just my first thought. Note: I am specifically talking about a big jump in minimum wage"
] | [
"The more money that is in circulation the lower the value of each denomination of that money. So a dollar today may get you a candy bar, but after the government prints a whole bunch of money that same candy bar may cost you three dollars."
] |
Back when war was primarily hand to hand combat, did kings/leaders of armies usually fight on the front lines or sit back and direct orders? | [
"Depends on the leader and the period. They would always use the best of equipment, improving their survival odds, and likely have the best teachers available. It was common for high nobility to take part and lead a military force in times of war (heck, that is one of the traditional reasons nobility existed), but some would lead from the front while others stayed back or in the middle."
] | [
"We have what's known as a hung parliament. This means that no one party has enough seats in Parliament to form a government. One party needs 326 of their MP's to have the majority and form the government. When no one party has enough MP's to form a government in their own right they can team up with other parties to get the majority. All Governments in the UK serve under the monarch, in this case the Queen. So when the leader of the party that won (or who has formed an agreement with other parties / joined a more formal coalition) wants to claim victory they go to the Queen and ask permission to form a government. The Queens role is ceremonial however she is still required to sign bills to pass them into law. This is known as Royal assent. She wouldn't ever use her veto."
] |
Did the Romans associate Asia with vulgar taste? | [
"They saw the East as not necessarily vulgar, but extremely decadent and effeminate, as opposed to their own order and stoicism."
] | [
"You should also keep in mind that \"Victorian attitudes\" were restricted to the middle and upper classes, which made up a pretty small ~~majority~~ minority of the actual population in Victorian England. The number of prostitutes in Victorian London would be mind-boggling to most people today. EDIT: Wow, I \"majoritied\" where I meant to \"minority.\" Fixed that"
] |
how can a group of arm people can go and occupying federal building refusing to leave and get acquitted as no crime has been done? | [
"For the charges that the prosecution brought against the individuals there was not enough evidence to convict them."
] | [
"People with lots of spare cash are at historic highs. Worldwide interest rates are at historic lows. Bank accounts are not good places to store cash right now, because they effectively hemorrhage around 1-3% of your wealth every year. So rich people all over the world are desperately looking for alternative ways to store their cash. Some of the cash is flowing into real estate in cities like London, New York, and Toronto. A lot of that real estate ends up sitting empty since it's just a \"cash store\". That is reducing the supply of housing in large cities which makes it more expensive for ordinary people to buy or rent a home. US citizens *are* protesting in affected areas like NY and SF. Their protests are directed more generally at the \"global elite\" rather than foreigners specifically. The US is a much larger country and the \"global elite\" is more of a mix of locals and foreigners than in Canada."
] |
Why does the body have an allergic reaction to something, especially if it hasn't experienced it before? | [
"That food contains a protein that your body can't digest or sees as a foreign invader due tue a gene mutation you have. So what your body does is it attacks it and your body reacts as if you are sick."
] | [
"I can't remember 100%, but in uni I remembering learning about how genetics is a huge factor, but of course environment plays a role too. So neurons in general have to reach a certain threshold to \"synapse,\" and in the case of pain/sensory neurons, the synapse=pain felt. If you have a higher threshold to reach in order to have a synapse, then you'll be less likely to feel pain for certain triggers, whereas someone with a lower threshold will have neurons that are \"triggered\" more often. Different people are born with different thresholds, but like a lot of people are saying in the comments, environmental factors can modify it! So in theory, you can become more tolerant to pain."
] |
Is it possible to determine how much of a medication's effect is a placebo? | [
"They do it by using a control group during the studies used to demonstrate the drug's efficacy. The drug is approved because it causes a significantly higher recovery rate in patients versus the placebo. The difference between the recovery rates of the two experimental groups is an important statistic which can be thought of as measuring how much of the drug's effect is due to placebo and how much due to the active ingredient."
] | [
"How do you tell the difference between a \"mathematical apparatus that works\" and something that is \"really real\"?"
] |
How do cough lozenges work if you’re swallowing it down your esophagus and your windpipe? | [
"Depending on the type of cough lozenge, they're mostly just offering a thick coating around your throat down to the splitting point of the esophagus/windpipe. Some contain ingredients that numb the nerves underneath the tissue in the throat, but most over-the-counter lozenges don't do much of that. If you're coughing a lot, it's probably because your throat is irritated, rough, and a little raw. A cough drop dissolves into a nice thick coating that sticks to the throat, smoothing out that rough surface."
] | [
"Think of your vocal cords as if they were rubber bands. Brand new rubber bands (like when you are young) are tight and bounce right back after being stretched. Now think of an older rubber band (like when you are old), having being stretched over and over. It doesn't have the same elasticity it once had."
] |
What are we smelling when we smell the "new car smell"? | [
"Mostly you are smelling \"outgassing\" -- the various plastics and adhesives used to make car steadily emit small amounts of gases. They do this a lot when they're brand new, then it gradually tapers off, but the materials continue to outgas even years later when heated, like when the car is parked in the hot sun. The gases are a combination of the material itself and the solvents used in manufacturing. Some of them such as formaldehyde are somewhat toxic. /edit: typo"
] | [
"The same reason you can walk through an airplane isle even though you are unable to move at hundreds of miles an hour (or fly). The same reason you are able to survive walking around outside even though the earth is spinning around at thousands of miles per hour. Ir more precisely, why you can swim in a pool even though that pool is spinning around the earth at thousands of miles an hour. The entire interior and the air of the car (or plane, or your place on earth) are all movin at the same speed. To the fly it makes no difference if the car is stopped or moving. It is sitting in a giant pool of air. All ot has to do is swim through that air."
] |
Why is it theoretically possible for absolute zero to exist, yet we have not experimentally been able to achieve this temperature? | [
"This is what I understand from my physics classes. I may be wrong. Temperature is how we measure the jiggling of atoms. The colder something is, the less they jiggle and zoom about. It's a measure of the kinetic energy the atoms of something possess. Absolute zero is the theoretical point where there is absolutely no kinetic energy in the atoms *at all*. No motion, no jiggling. How can you tell that something is not moving in your everyday life? You look at it, right? Well in order to \"look at\" these atoms we need to direct energy at them or receive something back from them. If they are not moving *at all* then what will come off them that we can measure? And if we direct energy at them, won't they then have some energy? This is my limited understanding of the subject."
] | [
"You can't just build complex molecules out of atoms as if you're fitting legos together. Certain configurations of atoms are unstable and are very difficult to create, or break apart immediately after you create them. It's as if you were trying to build a lego house, and you could never have just 1,2, or 3 walls up, you have to put all 4 walls in at once."
] |
Why is my wi-fi internet strength changing from 3 bars to nothing and back, even though my laptop isn't changing position at all? | [
"Any number of things in the house or hotel can disrupt a wireless signal. I'd imagine that certain disruptions would happen in cycles so that your signal strength will appear to fluctuate. Anyway, try moving your laptop away from electronics and machines and see if the behavior persists. Also consider the walls between you and your router."
] | [
"Are you looking for the scientific definition, or the layman's definition as it applies to airplane flight? I'm going to assume the latter. Turbulence in an aircraft is basically due to atmospheric circulation - hot air rises, cool air sinks. When you have masses of air near each other with drastically different speeds and/or directions, you have what is called wind shear. When a plane moves from a mass of air moving in one direction at one speed into a mass of air moving at a different direction and/or speed, the plane is buffeted around, the plane might suddenly sink or rise or yaw, etc. TL;DR - the wind is tossing the plane around."
] |
Why do things taste differently when cooked or burnt? | [
"Foodservice professional here: heating foods increases the general rate of oxidation(combustion) in the food product, this has several effects of note, not the least of which is the \"Malliard browning process\" which is the high temperature combination of a lipid, a protein and relatively simple starches that are common in items like bacon. this process is responsible for the delicious brown crispy outside on most cooked meats/high temp \"dry\" cooking methods. in addition proteins tend to contract into a more compact form under particular temperature conditions (eg. albumin coagulates at 115 F) and this causes some pretty dramatic changes in food as well due to them tangling amongst themselves. (eggs hardening, bacon curling). as for burned food, just don't do it. or eat it (i have heard tell that seriously burning certain foods can create nasty carcinogens) < heresay."
] | [
"Stoves heat a pan which in turn heats the pans contents. Even if you know the temperature of the heating element you don't necessarily know the temperature of the item you're cooking. Ambient temperature and the component of your pan will affect heat transfer. It also doesn't matter much for most foods. \"Hot\" and \"really hot\" are sufficient most of the time. When these are not sufficient you employ a thermometer that goes into the foodstuff itself and measures temperature directly. Ovens, by contrast, heat the air surrounding your food. Measuring the air directly is easy, although again this doesn't mean your food is at the oven air's temperature. Again, thermometers are deployed directly into the food when internal temperature is at issue."
] |
The difference between 1080i and 1080p. Which is better for gaming? | [
"The \"i\" means interlaced and the \"p\" means progressive scan. In 1080i only half the image gets drawn at a time, every other line. With \"p\" all the lines are replaced at once. Only the old CRT monitors could do 1080i, and its quite inferior to 1080p anyways. Unless you're using a massive old tube box, use 1080p."
] | [
"Brains easily perform many, many tasks hat are difficult for computer. Take that we know brains are optimized for pattern-finding. Consider intelligent life forms have to interact with a real 3-world and real time. Which means they can check their expectations. Testings a supposition is as simple as rotating an object while remembering the original pov. Babies don't have the ability to start with, but by the time they are of enough to talk everyone has extensive experience rotating real 3-d objects. Computers don;t live in a 3-d world, they use numbers to simulate one. They have limited learning and are not optimized for the task. Usually little to no ability to perceive or influence with the 3-d world. Living things can do things like perform multiple parallel advanced multi-dimensional calculus involved in say, catching a ball."
] |
If Darwin and Wallace independently developed theories of natural selection and jointly presented their findings, why is Darwin the one associated with it? | [
"There was a good programme about this on the BBC a few months ago. Bill Bailey successfully campaigned to get Wallace's portrait put up in the Natural History Museum. Unfortunately it's not on iPlayer any more but you can watch some clips here - _URL_0_"
] | [
"Mate, you're going to need to come up with a better example. That JFK cover is from 2013, ahead of the 50th anniversary of his assassination, a time when folks were inclined to overlook JFK's flaws. The 1968 Nixon cover is an allusion to the popular belief that Nixon lost the 1960 presidential election because of his appearance in his first televised debate with Kennedy. There's a famous poll that indicates those who listened to the debate on the radio thought Nixon had won. Those who saw it on television thought Kennedy had won. If you're interested in learning more, read Alan Schroeder's *Presidential Debates: Forty Years of High-Risk TV.*"
] |
The nomadic Timurids, Ottomans, and Manchus managed to hold onto their conquests for many hundreds of years, even into the 1900s in the latter two cases. Why did the Hunnic and Hepthalite empires disintegrate so quickly while the Timurids Ottomans and Manchus survived so long? | [
"China had a saying 胡无百年之运 that roughly means \"Barbarians Cannot Rule for a Hundred Years\", if you look at history at the states like Yan or the Yuan Dynasty this applies fairly well. So how did the Manchus rule for so long? They completely adopted the government and bureaucratic systems of the Ming Dynasty. By the 19th century the Manchu nobility could barely speak Manchu and were basically completely sinicized They were no longer the nomadic at the start of their conquests. The same is true for the Liao and Jin Dynastyies which also adopted Chinese customs, language, etc. Empires like the Huns were just nomadic tribes that were united under a charismatic Ruler (i.e Atila), that didn't have the structure and logistics to sustain itself like the Qing Dyasnty."
] | [
"I've been out of academia for a bit so I don't know how much weight this still has, but when I was in my Anthropology courses we learned about Tibetan polyandry. Basically, Tibetan inheritance rules dictated that each married son got a portion of the family's estate. As such, if each son married a different wife the estate got fragmented and the family's wealth diminished. The solution was for all of the brothers to share a wife, thus keeping the estate intact. I feel it should be stated that this is different from the concept of having male concubines, or of a single woman keeping a number of husbands, because in this instance the men were still in the advantaged position in society. It was a group of men sharing a woman, not a woman choosing to take different husbands. _URL_0_ (This is the first time I've felt qualified enough to try answering the question, I hope it is up to snuff.)"
] |
Why is it that one piece of paper will burn just fine, but, if I throw a big stack of papers into a fire, there will still be plenty of pages in the middle that never burn? | [
"Their surfaces aren't exposed to the oxygen or fire. Same reason food cooks from the outside towards the center or a block of wood burns outside first then burns towards the inside."
] | [
"You can hear things because there is a thin “drum” in your ear that sounds make vibrate. Your brain feels those vibrations and you experience it as sound. Air cannot go through that ear drum, just like a normal drum. Air gets to the other side through a different hole deep inside your head. The amount of air around you depends on how high up you are, the higher you are, the less air. If you go up or down quickly, the different hole that goes to the other side of the ear drum doesn’t let air through quickly enough, or at all if it gets clogged with goop, and the outside part of the drum (that you could see by looking in your ear) has a different amount of air pushing on it. Your brain knows how sounds work when both sides have the same amount of air, and gets confused when they have different amounts. When your ears pop, that is air moving into the inner part of your ear and making the pressure the same. Now you hear like normal again!"
] |
What was the state of Germany democracy before World War One? | [
"Hi, not to discourage further discussion of this topic but you might find [this thread](_URL_0_) useful, where I and u/kieslowskifan discuss a similar question."
] | [
"The way history class goes in Saudi Arabia is pretty much as follows: (We'll ignore the fact that much of the recent history glosses over some very important subjects) Grade 1-3: History of the Prophet Muhammad Grade 4-5: History of the Rashidun Khalifs (First 4 khalifs after the Prophet Muhammad) Grade 6-8: History of the Umayyad, Abbasid, Mamluk, and Ottoman dynasties, including their rise and falls. The first 3 or 4 crusades are in there somewhere. Grades 8-10: History of Saudi Arabia starting from the pact between the Saudi and AbdulWahab clans, up till the founding of the country. We don't study anything relating to WWI, WWII, or really anything post unification of Saudi Arabia in 1932. That's as far as it went for me since I majored in natural science in my last 2 years of high school. Arts majors continue to take history, but I've no idea what they study."
] |
Why do people with Down Syndrome have the same facial structure? | [
"A lot of the comments are giving a decent explanation as to why people with Down Syndrome look different, but not why they look the *same*. This answer comes down to the concepts of *genotype* and *phenotype*. **Genotype** is the genetic makeup of an organism. In this case, the genotype is having 3 copies of chromosome 21. **Phenotype** is the *observable* characteristics of an organism resulting from the genotype. In this case, it is the distinctive facial features of people with Down Syndrome. While people with the same phenotype (i.e. brown eyes) don't always have the same genotype (both Bb and BB = brown eyes), a person's genotype is much more predictive of their phenotype than vice versa (like everything in biology, there are exceptions). **TLDR;** Everyone with Down Syndrome has ~~a distinct~~ the same **genotype** which results in a distinct, striking **phenotype** - a phenotype they all share. Edit: additional clarification"
] | [
"It's stylistic. Exaggeration of features is very common in art around the world, even in the modern day. This kind of topic gets into an area that is rather vilified in the archaeological community. Links from one cultural group to another (i.e. \"Semitic features\" being present in some South African native populations) have been used to justify colonialism for centuries, and they almost always turn out to be false."
] |
Why do Emergency Services use blue and red lights on the top of their vehicles? | [
"It's been known since long before electric light that a lamp with a blue filter is most easily visible in fog, while a lamp with a red filter is most easily visible in sunlight. Both colors are sufficiently unusual in most environments to stand out against background lights and reflections. Also, red and blue lights have opposite psychological effects, with red light having an exciting effect and blue light having a calming effect. The combination of red and blue lights grabs your attention far more effectively than either alone. As for why they use them on the top of their vehicles, I'd have to observe that that's the most visible place to put them."
] | [
"The origin of the saying is unknown, although a form of it appears in the bible (Matthew 16:2-3). It has some basis in science and is a fairly good predictor of-though no guarantee-of weather at the mid latitudes in the Northern Hemisphere, where storm systems generally follow the jet stream from west to east. A red sky in the morning indicates a sun rising in clear eastern skies casting its rays on storm clouds approaching from the west. At night the clear sight of the red setting sun would tell a sailor that no storms are to the west. [Source](_URL_0_)"
] |
Why is rain measured in mm/inches, and not, say mL? | [
"You would be measuring rain in volume by area. If you divide volume/area you end up with height. That's why rain is measured in height."
] | [
"That has been done by Congress. The US officially switched in the 1970s. It did not stick. Those industries like the Sciences where it is much more useful switched, but general society where there is virtually no difference in the usages as we do not need to be that accurate in things there is not enough of a benefit to overcome the inertia of learned behavior and the cost of changing the infrastructure. To switch we would have to replace every piece of equipment in every home and building from the screws and nails used to build things, to the pipes in your walls, to the car that you drive. You would have to replace every single road sign in the nation. Etc. It would cost trillions of dollars. Most nations that switched did so before there was a lot of infrastructure or standardization of how things were made or built. Those that switched later like the UK are in a kind of half transition because of those same inertia issues. The UK still uses miles, and still uses Stones and pounds for weight."
] |
Do we have any idea what quarks might be made of? | [
"As far as we know, quarks are fundamental, like electrons, and are not made of anything smaller."
] | [
"Some research suggests that quantum mechanics plays a role in how we detect smells: _URL_0_"
] |
Is cancer becoming more common in recent years? | [
"Depends whether you mean incidence or mortality. See [this](_URL_1_) for death rates, generally going down: we are better at saving people from cancer. Incidence is [rising slightly](_URL_0_). Some of this might be due to the population aging, but it is also rising [amongst children](_URL_2_). And, obviously it varies tremendously by disease: melanoma rates are going up, lung cancer rates are going way down as people stop smoking. Your own observations are likely biased by the fact that you are getting older and are more likely to encounter people you know dying of disease."
] | [
"The popularity of comic book characters and acceptance of the geek subculture, mainly. people aren't scared to show that they enjoy these things anymore."
] |
Why, with enough food and resources on this planet for all of us, are people starving and dying of thirst? | [
"because there are always going to be people that will be looking out for #1 (aka themselves). distribution is also a big challenge. like aid was sent to africa, it was all taken by the local warlords. short of sending an army platoon to protect and distribute the food, it will be taken by whoever is \"in power\" in the local region."
] | [
"Hi OP, this is a cultural question, so it would greatly assist anyone considering answering if you could specify which culture you're asking about. For example, the name of a cultural group / country / geographic region, plus a rough time period. Otherwise, this question is simply too broad, as it encompasses almost the entirety of human existence. Thanks! Also, it may be worth cross-posting the question to /r/AskAnthropology or /r/AskSocialScience for their insights on this subject."
] |
Straight To The Gut: Why When Some People Put On Weight It Appears To Gravitate To A Certain Body Part IE. < Butt,Gut > Is There A Scientific Answer To This | [
"There is a fairly clear association with the distribution of fat and circulating sex hormone levels. Unfortunately, while there are pieces of the puzzle being worked out, I don't think anyone can say for certain why men gain weight in their gut, while women gain it on their arms/thighs/butt. It's related to testosterone and estrogen, but it's a complicated interplay of factors going on."
] | [
"Imagine firing a cannon. The faster you fire the cannonball, the farther it travels before gravity pulls it down and it hits the ground, right? Now imagine that you fire it so fast that as gravity pulls it down, the Earth curves away (because the Earth isn't flat, it's round). There's a precise velocity at which the cannonball will fall towards the Earth at exactly the same rate that the Earth curves away from it. That's what an orbit is. If it's slower than that rate, it will fall back to the ground, and if it's faster, it will drift away. Most satellites do lose some velocity over time, because space isn't a perfect vacuum, especially not at low earth orbit altitudes. So eventually satellites do slow down so much that they fall back into the atmosphere and burn up. Some satellites have thrusters on them to maintain their orbital velocity."
] |
Why do flavors like garlic and onion stick around in the taste buds so much longer than others? | [
"Normally, when you eat food, you taste the flavors when you're chewing it in your mouth. Once you swallow it, it goes into your tummy and gets broken up into tiny pieces and mixed around, and then your body takes those tiny pieces and puts them into your blood to make sure your whole body has the good stuff it needs. Usually, after this happens, the stuff that makes food taste good or bad has been broken up and doesn't have a taste anymore. Some food, like garlic and onion, have special little pieces that don't lose their flavor after they are broken up and put in your blood, so when the blood takes them from your stomach to your lungs, you taste them again when you breathe out. Also, these same pieces can be sucked up by your skin. To try this out, if you put some cut up garlic in between your toes, you can taste it after a little while. Edit: clearing up a bit of how it works."
] | [
"If you could definitively answer this and prove your theory, you'd probably win a Nobel Prize. There is a lot of theory on how memory works, but no one knows for sure. The best explanation would be that somehow the right combination of neurons in your head fired in just the right way to trigger that memory. I think we've all had it happen - some memory from decades pops up for no obvious reason. I've heard it theorized that we never forget anything. Every experience, every smell, everything we've seen heard or even thought - it's all in there somewhere, but we just can't access the memories because we don't know how or where they're stored."
] |
AV fistula for hemodialysis | [
"An AV fistula is synthetic \"tube\" that connects an artery to a vein. You can think of it as a hose pipe that runs between the two. They take blood from the fistula for dialysis instead of from veins. People who have to have regular dialysis usually have damaged veins due to needles constantly having to be inserted for blood to be taken out. The AV fistula allows for blood to be drawn without damaging any of the veins and makes the process easier. We actually can use other veins instead of the fistula but when you take a vein away from somewhere else you are decreasing blood circulation in this place. Alot of times people run out of veins for the doctor to take a graft. So the AV fistula makes the process of dialysis easier and is less complicated than taking a vein from somewhere else."
] | [
"For preventative measures: -having a donor who is a good HLA match -Depleting the bone marrow of T lymphocytes prior to transplantation -Depleting the patients T lymphocytes To treat GVHD, I have heard of using monoclonal antibody therapy and steroid therapy."
] |
The saying "If a tree falls in a forest and no one is around to hear it, does it make a sound?" | [
"The question is asking you to examine your belief in events without absolute proof or evidence. Logically, everything in your life's experience tells you that it will make a sound, but you have no way to prove that it will. In any issue, some things have to be taken on faith."
] | [
"Grab a tennis ball and a lamp. Turn off every other light in the room. Hold up the tennis ball. Half is lit, half is dark. If you are looking from the side (you can see the lamp and the ball) you can see some of the dark side of the ball. The ONLY way to see nothing but lit ball is to have the lamp directly behind you, with the ball just outside your shadow. EVERY other angle that you look at the ball will expose some of the dark side."
] |
Why exactly is there a pattern at the lower edge of this photo? | [
"I used to do darkroom photography a lot, and to me that doesn't look like any sort of chemical burn or radiation. I've had photos turn out like it; it was due to the film being crinkled inside the camera or during development, which makes the areas of the film on the bottom of the photo develop unevenly around the sprockets."
] | [
"If your talking about the thin lines that run all along the phone, them it's separation for the antennas in the phone. Your phone has different antennas for cellular/LTE connections, Bluetooth, wifi..... Those lines are either where the antennas are run or they separate different metallic parts of the phone that act as antennas."
] |
I have heard from a couple musicians that you can't capture the full timbre of an instrument in a synth. Can someone make sense of this? | [
"Timbre as a property of sound is a very complicated superposition of frequencies and overtones. A synth is an ATTEMPT to recreate the elements of overtones that \"describe\" a certain timbre by overlaying \"important\" overtones. But a synth has to \"stop somewhere\", and the reality is that the frequency domain of an instrument is essentially an infinite superposition of overtones. You can then get into the discussion of how human hearing is limited to frequencies 20Hz to 20kHz, but the discussion gets pretty theoretical at that point. It even becomes somewhat less of a discussion of the physics of sound and somewhat more of a discussion of the biology/neurology of perception. **EDIT:** Not to plug anything (because I have nothing vested in these), but the books \"This is Your Brain on Music\" and \"The World in Six Songs\" by Daniel Levitin offer great discussions of this and related topics and are great reads."
] | [
"Lots of chemical science and a base batch of fermented liquid to flavor. There isn't a lot of nuance in mass marketed booze, and practically every part of a flavor can be measured and replicated. The varietals are all put together the same way with tried and tested yeasts for exact Temps and times. They've removed a lot of the human variables."
] |
How are potholes created and why are there more of them after snow/rain? | [
"Temperature variance causes the pavement to form cracks, moisture from precipitation seeps into the cracks and when it freezes the cracks expand. When it thaws again the pavement breaks up and the traffic or plows remove chunks."
] | [
"They're either on a timer or on a sensor. Ever approach an intersection and see vertical and horizontal cuts in the pavement? That's where workers buried the sensors. Those work by detecting metal, not the weight of the vehicle."
] |
When did we refer to the Middle Ages as such? What is it the middle of? Eventually we will have a new middle age wouldn't we? | [
"Yes. The middle ages are a construct of the renaissance. No one is sure when they start or stop, and they start or stop at different times in different places anyway. Most historians dislike the term."
] | [
"Arbitrarily close to the speed of light. You're doing it right now in fact, at least compared to the reference frames of cosmic rays. > you think that some day we can hit light-speed? No."
] |
Is there something about drinking cold water that is physiologically more hydrating as opposed to drinking lukewarm or hot water? | [
"Well, when you've been running, you sweat. This is your body expelling excess heat by putting it into water droplets and excreting them, because water has a high [~~heat capacity~~](_URL_0_) [enthalpy of vaporization](_URL_1_). If you drink cold water, as it heats up to body temperature it absorbs a lot of that excess heat. So in addition to replacing the water loss from sweat, it also reduces your need to sweat in the first place. EDIT: thanks for the correction, VoiceOfRealson."
] | [
"Yes. For conduction and convection forms of heat transfer the rate of heat transfer is directly proportional to the temperature difference between the atmosphere and the object. If your ice is 32F (assuming you haven't cooled it past its freezing point) and you refrigerate it at 32.1F your ice will melt about 100 times slower than if you refrigerate it at 42F. Note: This assumes your atmospheres and substances are the same between the two different scenarios with only a change in refrigeration temperature. It does not take latent heat of fusion into account. Nor does it take into account the affect the melted water will have on the ice. Realistically, as the ice melts it will transfer energy from the air to the melted water to the ice as well as the ice directly, so it changes from a strictly convective heat transfer question to a dynamically changing combination of convection and conduction as soon as it starts to melt. edit: because /u/jade_crayon is completely right."
] |
Why did Emperor Joseph II of austria "order that bodies should be buried in unmarked graves, without coffins or embalming" | [
"Joseph II likened himself as an enlightened monarch and often tried to enact Enlightenment principles in his decrees. One of these principles was to simplify burials and funerary practices. He wanted to change seemingly wasteful Austrian funeral culture of elaborate coffins and embalming. In doing so, not only would it lessen the fiscal burden of funerals, but also increase hygiene and alleviate shortages of timber. So he issued a decree in 1784 declaring, that save for high nobility, people would be buried in canvas sacks in unmarked mass graves outside of the city limits. There was an immediate pushback from the public about this decree and Joseph II rescinded it, but his decree that there could be no burials within walled cities or within churches stood."
] | [
"Ha, I wrote a paper on this once. If I had to boil it down to one cause... I would say its the fact that in the US railroad infrastructure is (mostly) owned by private companies, which is fairly unique in the world. The US has the most sophisticated and impressive freight railroad transportation in the world (think about how that cheap toy you bought at walmart got to new york, or chicago.. a train had to take it very cheaply from the ports in the west coast where it was brought into from china). So, because the railroads are privately owned, publicly operated amtrak trains do not get priority. This is actually a source of constant tension, where the freight companies want their trains to be on time, but by law, they need to give some space for amtrak trains, which ends up costing them money. So in the US, passenger trains end up getting low priority, while elsewhere in the world, where the railroads are owned by the govt, passenger trains get highest priority."
] |
why do older adults' voices sound different than younger adults? | [
"A different set of vocabulary does not affect voice sound production as the prior post mentioned; that has to do more with a language difference between generations rather than the physical production of voice. The term for typical voice changes as you get older is presbyphonia. As we get older, all of our muscles age. This includes the same ones we use for speech. They become more worn, damaged, take longer to recover from injuries and are less elastic compared to when you are younger. This is not to mention any abnormalities that can be caused from lifelong habits (smoker's voice, cancers, granulomas on vocal chords from vocal abuse, etc.) Older people tend to drink less water as they lose their sense of thirst and even something as simple as basic hydration can affect your vocal quality."
] | [
"A part of it is that we have fewer stem-cells ready to take the place of any damaged cells. As we grow our initial stem cells take find their homes and begin specializing. We always have a certain number of stem-cells in our bodies, but fewer as we age. Also, each time a cell divides it loses a link in a chain of \"telomeres\". After it loses all its telomeres it will stop dividing. Obviously as we age, fewer cells are replicating themselves to replace damaged ones. Under normal circumstances you don't need your cells to keep diving except for maintenance, so this is expected behavior, but can lead to longer recovery times from injury."
] |
Why did the fourth crusaders sack Constantinople? How did they get so off-course from their original goal? | [
"The Crusades were often as much about money and personal glory/fame than any real religious convictions. In very simple terms, sacking Constantinople during the Fourth Crusade was about getting loot and booty. There were numerous other religious and political reasons too, mainly involving the growing schism in the Catholic Church and the machinations of the Pope and the Italian city states against their rivals to the east."
] | [
"I posted on ActiveHistory yesterday about a controversial statue of Edward Cornwallis in Halifax, Nova Scotia. Cornwallis, the renowned founder of the city, also has a little bit of historical baggage wherein he proclaimed a bounty on Mi'kmaq scalps in 1749 - a fairly bloodthirsty act. Similarly, he expressed the desire to clear Nova Scotia of the Mi'kmaq population. In any case, his statue has become a site of public contestation, has been defaced a number of times by native rights groups, and has been debated extensively in the media. Since much of my own work deals with public representations of the past, I thought that I'd weigh in. If any of you would like to take a look at my online article, I'd be happy to discuss any issues or questions you might have. It can be found [here, at _URL_3_](_URL_4_)"
] |
I use two weather apps. One of them says 85% chance of rain this afternoon, the other one says 0%. Why are same-day weather forecasts so wildly inaccurate in 2016? Shouldn't we be kind of good at this by now? | [
"Adding to other comments on weather modelling and data, it depends on where the raw data comes from. In Australia, the government weather bureau is not used by most popular weather apps - e.g. Apple weather, Yahoo weather and Android's default weather app. They use a service called Weather Underground, which crowd-sources its raw data from a network of personal weather stations. For this reason, the most popular weather apps for this region always differ from official sources. I don't have data on which is more accurate. One may assume the official government source with their vast resources and local knowledge, but if the last 15 years of internet-powered business disruption is to go by, the crowd-sourced data may in-fact out perform the established services."
] | [
"The type of crime where being 'least expected' actually matters is exceedingly rare. Most crime is not Ocean's 11-style heists, but either interpersonal conflicts (where the location of the crime is dependent on the location of the individual you're targeting) or opportunistic crime (where the location of the crime is dependent on what you see in your daily life). Indeed, for most crime, it's as easy - if not easier - to predict crime by looking at *victims* rather than criminals. If you open a liquor store in a certain neighborhood, there's no guess who will attempt to rob it. But *someone* probably will. In contrast, if you open an upscale wine shop in McMansionland, you're unlikely to ever experience a theft unless you make a particularly bad employment decision."
] |
Why did we skip 3K TVs? | [
"Common display resolutions tend to just be previous standards multiplied by 4, as that way you can scale previous content up and future content down with no calculations as its a straight conversion. 1080p was the previous standard, 4K is literally just 4x1080p. 720p was the standard before 1080p, which got multiplied to 1440p, which never really got widespread adoption as it wasn't 'enough' over 1080p to justify."
] | [
"My guess? When you're dealing with a lot of makeup, prosthesis, special effects its easier to hide flaws. You can see acne under makeup in high def, you couldn't really see that back in the day. Just a guess."
] |
How jet-fighters can detect when a missile is locked onto them | [
"A [Missile Approach Warning](_URL_0_) system can use RADAR, Infrared or Ultra-Violet sensors and a computer to detect incoming missiles. Radar looks for the actual missile (smaller ones are hard to detect), Infrared and Ultra-Violet look for the heat that the missile is making. Each kind has its own strengths and weaknesses based on what kind of missile is being fired at them and the weather the airplane is in."
] | [
"For direct downloads from a server, they have to either seize the logs of the server, or work with ISPs or other men in the middle to figure out who is downloading what. For bittorrent and similar peer to peer systems, it's pretty trivial. Find a torrent you want to monitor, join the downloaders, log the IPs of the peers. There is dedicated software for this and companies which do this for film studios/distributors, lawyers etc. Once you have the IPs, subpoena the ISPs owning the IPs to reveal who the person at that end is. Then take that person to court. As to how they decide who to go after, no idea. I guess it's a mix of going after the biggest infringers, \"setting examples\" and doing what's directly profitable (e.g. sue everyone who downloaded a particular movie in a jurisdiction where they are likely to win)."
] |
Why are girls supposed to shave their legs/armpits, etc? | [
"Social acceptance. Ever hear an American's take on French women? Society says you look better when you shave your legs, wear tights and high heels! Also, some women do it for hygiene. Everyone sweats a lot from the arm pits, and if you have hair there, it sticks around and creates some BO."
] | [
"Several things. On an installation level, each program you install adds 'weight' to the operating system by giving it more tasks. These aren't always removed cleanly when you uninstall, which makes it important to reimage your computer about every year. Additionally, if you use a standard hard disk drive, the drive fills up and files are 'fragmented' in pieces across the drive, requiring extra time to access. More generally, technology is always advancing, so the target of what is a powerful computer is moving. What was \"Good\" or \"Great\" last year is merely \"average\" this year, and might be \"Mediocre\" next year. Developers write software in mind with a general idea of what hardware is on the market and how fast the slowest computers are, and so as time goes on, the programs become more complicated with more features, aimed at newer computers than yours, and while the weight of the program is increasing, your computer's processing capacity is static without upgrades."
] |
The point of keeping documents "classified" for X amount of years | [
"To protect people and information that shouldn't be public knowledge. Things become declassified years later when the information they contain isn't considered damaging, or that people named in such documents are probably dead or otherwise safe from danger."
] | [
"In many cases the recording company just wants to resell you the same album again. Depending on the fidelity and condition of the original recordings you sometimes can get better versions that what was originally available in the 70s, but you're not going to pull a crystal-clear version of an old Led Zepplin album off a forty year old tape."
] |
Is the average distance large enough between Pluto and Earth that the constellations would appear different? | [
"It's a detectable difference (you can read about an older mission called [Hipparcos](_URL_0_) to measure distances to the stars), but rather miniscule. The current distance to Pluto is .00051 light-years, while the *very* closest star is 4 ly from here."
] | [
"A long time ago in places like Greece, Rome and even before that in really, really long ago places like Sumeria, and Egypt people made up stories about the stars/planets and the pictures they thought groups of stars made. These stories were usually about beings they considered to be gods or demigods (the word demigod here means \"half-god\" or \"almost-a-god\"). At one time Rome was pretty much in charge of the known world for a really long time (around 1700 years). During that time they shared their stories about stars and planets being where the gods lived with everyone they were in charge of who didn't already have stories like that of their own. People got used to the idea, and it kind of stuck. Some scientists/astronomers today do it because really old texts and star charts have them recorded that way, and some because they think the old stories are cool or because after so many years it's kind of a tradition."
] |
Why are atomic clocks considered the most accurate? | [
"Atomic clocks are not the most accurate, nuclear clocks are. However, they cannot be built yet due to some issues knowing the energy and lifetimes for low level nuclear states."
] | [
"They use a wavelength of light that is cancer causing. Do you want to sit under a cancer causing light? Plus, they aren't all that effective to stop, say a sneeze from transmitting to another person. It takes some time to kill the germs."
] |
What is more environmentally friendly to drink soda, a aluminum can or a plastic bottle? | [
"Thank you for this helpful post. As a mostly uneducated consumer on this topic, I have often wondered the answer to this very question. My primary concern is which one causes the least environmental damage to the actual earth after it's thrown away, as I recently found out that even though my town collects my recycling, they don't actually recycle most of what I put in there. They just collect it and throw it in the same garbage pile with my other stuff, which is infuriating. So I'm trying instead to not add to the overall problem by spending my $$ on products that have the least negative impact on the earth to begin with. Considering these facts provided on this thread, would that be glass I wonder ?"
] | [
"Your whole high school is in the gym for an assembly. The presentation comes to an end and everyone needs to leave all at once. If you never open the doors, people will never leave. If you open one door, how long will it take for everyone to leave? If you open all the doors, how long will it take for everyone to leave? Relate this to your problem. Basically, it doesn't matter how fast or slow you open the bottle, the air will equalize anyway. It's only a function of how fast it equalizes."
] |
Plato records a visit in Athens by an Indian wise man who met and talked with Socrates about philosophy. How plausable was that visit? Could the reverse ha taken place? | [
"By reverse you mean any Greek philosopher visiting India not Plato specifically?"
] | [
"A woman named Frances Wright did something like what you are asking in 1824. In Memphis, TN she bought two thousand acres of land from Andrew Jackson and would buy slaves. On this land she set up a co-operative labor system where they could basically work off their price of purchase and then they would be set free. EDIT: Forgot to mention that the name of this place was Nashoba. Nashoba is the Chickasaw word for \"wolf.\" Source: Gerald M. Capers Jr.'s *The Biography of a River Town*"
] |
Recommend me a book about slavery | [
"Morgan, Edmund. *American Freedom, American Slavery* Berlin, Ira. *Generations of Captivity.* He has many books on American slavery, and is one of the leading experts, so you probably can't go wrong with his work. Davis, David Brion. *Inhuman Bondage*. Blight, David. *A Slave No More.* - This is an interesting blend of slave narrative and historical interpretation by one of the best working historians. For a first-hand, primary source, you can do no better than the most famous surviving slave narrative, the *Narrative of the Life of Frederick Douglass, an American Slave.*"
] | [
"_URL_0_ The Geography of Time by Robert Levine. Blew my mind the first time I read it."
] |
How have denim blue jeans maintained their popularity while pretty much every other type of clothing has gone in and out of fashion? | [
"Cuts and styles of jeans have come and gone over the years. Sure, denim's been a staple of fashion since the 60s (when they became acceptable to wear off the farm) but we've seen... Different cuts: bell bottoms, boot cut, straight leg, skinny jeans, pipe legs (eg - JNCO), low-rider waist, normal waist, high-cut waist, etc Different finishes: Indigo, stone washed, acid washed, galaxy washed, distressed, etc Denim's a comfortable, durable, (originally) inexpensive fabric to work with. It's no surprise that it's had a long life as typical American casual/semi-casual wear."
] | [
"[Here](_URL_0_) is a good NPR article answering that exact question. ----------------------------------- To start, we need something for a currency. Life is way easier with something for a currency. So what do we use? We need: * Something rare but not too rare * Something that's not a gas * Something that won't explode * Something that won't corrode easily and fall apart * Something that you can melt using tech earlier than 200 years ago * Something that's not radioactive and will kill you * Something we discovered earlier than 200 years ago That leaves gold. Silver is a close second -- which is why it's still used -- but it tarnishes. Which means gold is our boy. It wasn't a matter of choosing gold; it was a matter of eliminating everything else."
] |
Was diabetes a health concern before we had all the processed foods we have today? | [
"Diabetes is one of the oldest identified diseases, dating back to ancient Egypt: _URL_0_ Incidently, a lot of what is seen as diseases being more prevalent in modern society is really just us getting better at diagnosing things."
] | [
"As a reminder, [top-level answers](_URL_0_) in this community need to be \"comprehensive and imformative.\" Single-links to Wikipedia and unsourced opinions do not clear that bar. This question already rests on a part of history hamstrung by the fuzzy diagnostics of diseases in the past and an almost unavoidable bias in sources. Please ensure your answers take that into account."
] |
Had any cultures proposed that stars were other Suns further away before it was scientifically verifiable? | [
"If you don't get an answer here, try /r/askhistorians, /r/askanthropology, or /r/historyofscience"
] | [
"Not a historian, just someone who likes to lurk and learn new things, but I can maybe point you to a few similar questions I’ve seen about kids and their obsessions while you wait to hear from an expert. [This post](_URL_2_) has an ancient Roman source from u/rkiga that mentions a toddler obsessed with birds. Further down in the comments, u/Kyncaith briefly discusses Onfim, a young boy whose doodles on birch bark were preserved, and that these drawings show he daydreamed of becoming a warrior and drew himself as a wild (but friendly) beast. Link to the source [here](_URL_1_). u/kingconani recently [discussed](_URL_0_) how literature in the 19th century for young girls let them pretend to be princesses, still a common obsession as evidenced by Frozen mania. Those are the only two I remember seeing off the top of my head, but hopefully it will tide you over until you get a more detailed answer from an expert."
] |
What is a plant's immune system? | [
"Compartmentalization of fungal infections is a tactic used by trees. See Dr. Shigo's CODIT. Shigo, A. L. (1984). Compartmentalization: a conceptual framework for understanding how trees grow and defend themselves. Annual review of phytopathology, 22(1), 189-214."
] | [
"Nasa, among other groups with space exploration in mind, are asking that question themselves: _URL_0_ It seems the biggest problem to overcome is the low atmospheric pressure, which sucks the already rare water out of plants. Nutrients don't seem to be a problem."
] |
There are 1 Billion Hindus also from relatively poor countries. Why dont they have any terrorist incidents against the West like Islamic terrorists? | [
"I'm a Hindu and would like to point out that the potential to justify violence using religion is definitely there in our religion as well. The Bhagavad Gita is essentially a conversion between God and a warrior justifying why it is his duty to fight and kill in an pending civil war. The religion is tempered a bit by the concept of Ahimsa or non-violence and the belief in karmic justice to redress wrongs committed. It should also be noted that the effects of dehumanizing others is less toxic when you believe in the equivalence of human and animal souls due to reincarnation. In addition, Hinduism has lived along side other belief systems for long enough that it has mellowed out. I think any strongly held belief system can become intolerant and violent in the absence of the opposing voices and an echo chamber. This is why everyone must fight for the right of free speech and encourage tolerance of speech one disagrees with."
] | [
"Pretty much. In fact, California in general had a rather high population density in pre-Columbian times. Game was indeed plentiful, and so was plant-based food (which is a given considering the abundance of animals). The Yokuts, the Miwok's neighbors to the south, had an average of 70,000 people throughout their territory. While Native Californians (aside from the Mohave) never developed full-on agriculture, they still had a practice of land management. Tribes would burn stretches of land to clear old growth, rejuvenate the soil, and encourage the growth of perennials, transforming shrubland or forested areas into active fertile plains for the nourishment of both game and people."
] |
What's the difference between Diet Coke and Coke Zero? | [
"**Coke Zero:** Same taste, artificial sweetener. **Diet Coke:** Different taste, artificial sweetener. **Coke Life:** Same taste, mix of artificial and natural sweetener (so 60% less cal instead of ~0cal)."
] | [
"Here's a link to a copy of the figure that convinced the community: _URL_2_ The x-axis shows the redshift of the supernovae, and the y-axis shows how bright they are. The dashed line shows where the points should lie if the universe had no cosmological constant (i.e., if it were not accelerating). The solid line shows where the points would lie if the universe has a cosmological constant. The bottom panel is the \"residuals.\" This is the difference between the data and each of the lines. You can see that more points lie above the dotted line than below it, and the points seem to straddle the solid line pretty well. More rigorous statistical tests showed that the dashed line (no acceleration) is excluded with greater than 99.99% confidence. You can read the original papers here: _URL_0_ and _URL_1_"
] |
Why do we get headaches? What causes it | [
"\"Although it may feel like it, a headache is not actually a pain in your brain. The brain tells you when other parts of your body hurt, but it can't feel pain itself. Most headaches happen in the nerves, blood vessels, and muscles that cover a person's head and neck.\""
] | [
"Differing Alpha and Beta levels within the brain. Everyone is wired differently and most likely the time you go to bed affects the said levels. This also changes when you age as well. There's a japanese article that goes into detail about this but I can't find it"
] |
Why does a lens perform a Fourier transform on light? | [
"Maybe this gives you some hand-waving intuation: Spatial Fourier transform takes position space into wavevector space. A lens focuses parallel bundles of beams into a single point. So everything that was described by the same wavevector beforehand shares the same spatial coordinate in the focal plain of the lense. So the spatial coordinate after the lens contains the information that was encoded in the wavevector before the lens which in mathematical terms corresponds to a Fourier transformation."
] | [
"Binary logic is used to carry out simple arithmetic, such as addition, subtraction, multiplication and division. I cannot delve into the programmatic details. Transcendental functions like sine, cosine, inverse trig functions, integrals and so on are calculated using a series expansion called a Taylor Series. In short, every \"elementary function\" has an equivalent expression in the form of an infinite sum in polynomial form that's called a Taylor series. Using a known Taylor series, a calculator can carry out simple addition and multiplication operations, accurate to a number of decimal places that your calculator truncates at in order to calculate the value of an otherwise complex operation (trig functions, logarithms, etc.). For example, I believe a TI 83 truncates at 12-16 decimal places or so. MATLAB truncates at 16. An infinite number of terms isn't necessary on a calculator because it has finite memory to store decimal places. EDIT: Clarity"
] |
How hot is a nuclear meltdown? Are there materials like tungsten which could stay solid indefinitely? | [
"An uncooled core will heat up until (a) the environment can transport away all the heat generated or (b) the core material evaporates. The latter is obviously not what you want. A big tungsten container is not a good heat conductor - the interior would heat up until the tungsten melts and the block disintegrates. The higher melting point of tungsten just means it will get hotter. You have to cool it actively until the heat dropped enough to make passive cooling possible. The temperature then depends on the cooling."
] | [
"A similar design was at least mentioned for Project Plowshare, and it considered detonating nukes inside the earth's crust to heat up underground water. It does not seem to have a code name, only known as \"Geothermal Power Plant\" as far as I know, so it would seem there no detailed plan was even created. Just because something is possible does not mean it makes a lot of sense. If you can spend large amounts of resources to build a tokamak then why spend large amounts of resources to build an infernal machine."
] |
Cuteness as evolutionary trait? | [
"If you look at [cuteness](_URL_1_) and [neoteny](_URL_0_) in Wikipedia, it says, \"Human children have evolved to stay neotenized longer, so human adults will care for them longer due to their cuteness.\" There's also mention that \"'adult mammals' are hard-wired to have their 'aggressive behavior' inhibited and exhibit 'caring' and 'nurturing' attitudes toward the appearance of 'mammalian infants'.\""
] | [
"Yes, there are many examples. These are just a few: * Chimpanzees: [Ex. 1](_URL_2_), [Ex. 2](_URL_3_), [Ex. 3](_URL_0_); there are [many more](_URL_1_). * [Monkeys](_URL_6_) * Whales: [Ex. 1](_URL_5_), [Ex. 2](_URL_4_) * Birds: [Ex. 1](_URL_8_), [Ex. 2](_URL_7_)"
] |
Are insects still "alive" or "conscious" if they are infected with a parasite? | [
"It really depends on what you mean by 'conscious.' Yes, it's alive. Horsehair worms use chemicals (possibly ones that mimic other insects' pheromones to guide the insect around, it's not fully understood) to influence the host's brain and make it do what it wants, usually jumping into water to release the worm. It's not like the worm is physically manipulating its body like a puppet, so it's alive. Does it have voluntary control? Is it conscious? Was it ever? Insects have very simple neurology. It's a biological machine acting on instructions embedded in its neural makeup and the parasite is introducing chemicals that alter those instructions. More like driving a car than hijacking someone's brain, though keep in mind the worm isn't any more aware of what it's doing than the bug is. The worm is just releasing chemicals according to instructions embedded in even simpler neurology."
] | [
"When we use the term \"information\" in this context, we really mean something rather mundane. The idea is this: In quantum mechanics, two distinct quantum states cannot evolve into the same state. Classical calculations indicate that any two black holes of the same charge, mass, and angular momentum are indistinguishable, and so when they decay via Hawking radiation, they'd release indistinguishable products. So two different quantum systems would appear to be able to produce the same final states of Hawking radiation. This is the paradox. Solutions to the paradox that involve preserving the information mean that the black hole is actually different depending on the quantum state that formed it, and consequently the radiation it evaporates into will be different. Thus, in preserving the information, we mean that the final state was uniquely determined by the initial pre-black hole state."
] |
why do smokers spit so much when they are smoking? | [
"Possibly because of the taste a smoke tends to leave in your mouth. I dont do this but my boyfriend does. . He could also be getting nauseous. .which tends to produce a lot of spit."
] | [
"Honestly the rules for this sub is a pain in the ass for questions like this. This can be answered easily, but the rules says I have to have a shit ton of words to comment. But the reason is simply, it's for the show. It's an act to entertain the audience"
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Why do some companies require only a credit card number and expiry date to charge you, while others also require a cvc code and/or cardholder name? | [
"CVC codes are often optional to the merchant. They can choose to obtain them and maybe get a lower processing fee, or to ignore them. Especially on phone transactions, it may be easier and/or more pleasant to the customer (and merchant) to minimize the amount of data communicated, even if it requires the merchant to assume more risk or a higher processing cost. PIN/Signature collection is far from standardized / mandatory for online transactions. I'm not going to comment there."
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"A few reasons, first you may remember from high school chemistry the ideal gas law. PV=nRT, where P=pressure, V=volume, n= number of moles, R is a constant and T is temperature. If you spray a pressurized gas (the propellant in the can), which is typically butane or propane, as the gas comes out of the spray nozzle it's pressure decreases as the volume the gas expands. On the other side of the equation, n and R remain unchanged, so the only variable that can change is T. In math terms compressed gas = PV/T = nR decompressed gas = PV/T = nR Since nR is the same in both equations, it can be rewritten as PV/T (compressed) = PV/T (decompressed) That's for the gas part. The second is, a lot of spray perfumes and deodorants use alcohol as a base. That alcohol evaporates when it's sprayed onto the skin, so there is an evaporative cooling effect as well."
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In Ancient Egypt, how far did the annual floodwater spread from the Nile? On average, how deep was the floodwater? What measures did the Egyptians take to prevent their infrastructure from being flooded, while still guaranteeing that their crops would be flooded? | [
"Follow-up question: How much did the Aswan dam affect the system? Did the construction of the dam have a significant effect on the benefits brought by the floods?"
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"Yer not alone in askin', and kind strangers have explained: 1. [ELI5: how do metal detectors work? ](_URL_2_) 1. [ELI5: How do metal detectors work? ](_URL_1_) 1. [ELI5 how do metal detectors work? ](_URL_3_) 1. [ELI5: How does a metal detector work? ](_URL_5_) 1. [ELI5: How do metal detectors work? ](_URL_7_) 1. [ELI5: How do metal detectors work? ](_URL_4_) 1. [ELI5 How metal detectors work. ](_URL_8_) 1. [ELI5: How metal detectors work and if they detect all elements classed as \"metals\" or only specific metallic elements ](_URL_6_) 1. [What do metal detectors actually detect?? ](_URL_0_)"
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How Kurds managed to preserve their culture and not to blend with Arabs, Turks of Iranians? | [
"Kurds have traditionally lived in the mountains and have been extremely good at defending them. Most of the post-roman invaders (Arabs, Turks, mongols etc) were desert/steppe nomads and lacked the skills or desire to repopulate hilly terrain filled w warlike Kurds. Anyways, Kurdish is a linguistic relative to Iranian, so compared to other warlike hill people (the basques, etc. ) Kurdish isn't that different from its neighbors. Also Kurds are majority Muslim and have been very well integrated into regional polities in the past (Salah al din/Saladin might have been Kurdish for instance)."
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"The species in question are all social species. That's what makes the big difference. If a species isn't social it won't have deep instincts to interact with its own species, let alone having that transfer over to other species. Also, regarding the bird example, it is more common than you think. In the wild [many bird species form multispecies flocks](_URL_0_), and some of these are highly stable."
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the theory of evolution and why it is technically wrong to say "We evolved from monkeys" | [
"We share a common ancestor with monkeys. That is not the same as evolving from them. It's kind of like saying you're descended from your cousins. You're not. You share a common ancestor (your grandparents) with your cousins, but you're not descended from them."
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"Think of it this way. Take all the people alive today and group them. Now take all the mothers of that group - let's call that group M. This group will consist entirely of women, and will be smaller than the first group, because everyone only has one mother. Now consider another group - all the mothers of group M. This group will very likely be smaller still, again because everyone only has one mother. Now keep extrapolating this back, and eventually you will reach one woman, who is the mother to everyone in the group 'before' her, and so the common ancestor of everyone in all the groups preceding, ie, everyone. It's important to note that Mitochondrial Eve was not the only woman alive, she was just the only woman to have descendants in the matrilineal line who are still alive today. This clears up some misunderstandings: _URL_0_"
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