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ji8nq5 | Technology | Did the first people to own a television have nothing to watch? Or did the first broadcasts go out to nobody? | In the early days of broadcasting, there would be very few channels (perhaps only one), and TV would only be available at set times of the day, for example a news broadcast, and then they'd stop broadcasting and the TV would just pick up static for the other ~23 hours of the day. | 26 |
7tnxr8 | Biology | Why does cold water feel great in our mouths, even when we are cold, yet painful on our skin? | Your body tries to maintain a certain temperature for it to function properly. 37°C is the best for your basic respiratory (blood circulation, biochemical reaction) processes. So most of the mammalian bodies designed a specific way to make sure these temperatures stay stable, even if we are in the arctic and breathing -15°C air or even drinking ice water. In case of the drinkning-water, you have to image your mouth as a water heater. Your body and blood exert a huge amount of heat, and if you (for example) take your fingers, put them in your mouth and feel the inner layer, you will feel that the blood vessels are very close to it and are radiating a lot of the 37°C your body is trying to maintain. So every time you sip cold water, your mouth tries to bring it to an preferable temperature in order to be able to swallow it und transport it into your stomach. If you swallow a huge amount of very cold water, without pre-heating it , you can feel the cold water in your stomach. And for most people this feeling is not a prefered one. And why does cold water hurt on your skin? We have special thermoreceptors, only on our skin, which tell us through pain that the Environment is not good for us. Still the same train of thought. The normal Ned has about 2,5 m^2 skin, very big area for our mass to loose heat. And if you do the same experiment you did above with your finger in your mouth and compare it to the temperature on your skin (everywhere despite arm- and kneepits) you will feel, that it is not THAT warm. That is because we have a natural "fat"-coat around as, that keeps our skin colder then our inner temperature in order to prevent heat loss. And if that skinlayer gets extreme cold (even colder water) our body tries to tell us, that it is not an desirable surrounding for maintaining the inner temperature - serious danger of hypothermia. So we have special thermoreceptors, only on our skin, which tell us through pain that the enviroment is not good for us. | 1 |
lhs5pi | Other | Click-Through Rate (CTR) I need this explained to me like I am a 15 y.o. teenager | You can put these all in one question you know lol. Click-Through Rate is a percentage of how many people actually click on your advertisement compared to how many people see it. If 100 people see the advertisement but only 2 people actually click on it to get more info about the product, the click-through rate would be 2%. If 100 people saw it and 90 people clicked on it, then the CTR would be 90%. It helps a company figure out how effective their advertising strategy is (are they putting it on the right sites, targeting the right people, etc.). A higher rate is better. | 1 |
6x22rz | Chemistry | Why is milk so bubbly? | Not sure what you mean with bubbly exactly but when you pour a glass of milk a little air gets trapped and will surface as bubbles. So it's most likely that the answer to your question is because of trapped air. | 1 |
73or0s | Economics | how do car dealerships make money when they claim the markup on new cars is only a few hundred dollars? | Kickbacks for selling a certain volume, the service department, higher end vehicles with more markup, the pre-owned department, kickbacks from finance companies, warranties and dealer packages | 9 |
6pi8q6 | Technology | Why do cars have AC buttons when you have the ability to change the temperature? There shouldn't be a difference between a hot 69°F and an AC 69°F? | The temp knob controls the mix of cold air and hot air. Hot air is generated by waste heat from the engine. With the A/C off, cold air is from the outside. So the coldest it can get is the ambient outside temp. With the A/C on, cold air is from the A/C system, which can be colder than the outside temp (in spring/summer, at least). | 1 |
6kcjzq | Engineering | How are modern buildings designed to be earthquake-resistant? | Structural engineer here and I would like to give my input as I am not happy with the top comments/answers. They do not directly answer the question and also have false statements. For example, mass tuned dampening is one method of helping a tall buildings reduce motion it is not required (e.g. Burj Khalifa does not have one). Also a statements such as buildings not absorbing energy or beams "failing" first are incorrect. So let me begin, In a seismic event different waves travel through the ground, P-waves, Shear Waves, L-waves. These waves cause motion in different directions, up and down, side to side, compression and tension etc. The side to side motion is the most damaging so let us focus on that. Imagine a simple "lollipop" structure. Single slender column supporting a ball of mass concentrated at the top (think water tower). As the ground shakes the the motion is transferred into the building. The displacement, velocity and acceleration of the mass depends on the stiffness of said structure (effective length, modulus of materials, moment of inertia). If the resonant frequency of the structure matches that of the earthquake that is very bad! You want a resonant frequency that is lower so it "attracts" less load. If it is very stiff it will excite just like the ground and forces will be high, F=ma. Think of a building as lollipops stacked on top of each other. Once an engineer determines the amount of force at each story of a building (stiffness matrix x displacement) then they design the seismic force resisting system (SFRS). To resist a lateral force several methods can be used depending on cost, efficiency, architectural requirements etc. Some methods include compression tension braces, moment frames and concrete shear walls. In tall buildings or seismically active regions or post disaster buildings (this is my field of experience, i design hospitals) the forces will be too high to design for. So engineers will instead allow the structure to yield and deform and absorb energy. If there is no yielding there is no energy absorption (think spring that you push and pull in the linear region, it never loses its shape). One can scale down the forces if they allow for more yeiding and energy abortion, but the cost typically goes up, need more concrete confinement, better welded or bolted connections. If the deflections for the tall building is too high then a liquid mass tuned dampener an be used. The mass always moves in the opposite direction of the building. Fun fact Tapei 101 turned theirs into a tourist attraction. The burj khalifa does not even use one ! it is not always necessary. These tall buildings use a techniques like shear walls in a triangular shape (think tripod wth legs deployed far out as possible) or non uniform cross section to "confuse" the wind and prevent resonance. If the ground vibrations are too high techniques such as isolation pads can be used, think marbles underneath your houses foundation. Ground shakes but building just sits on top. These are advanced methods that are not common in your average mid rise. Feel free to PM me with questions or corrections. | 29 |
b9u7ed | Other | Why don’t car insurance premiums decrease automatically as the car deprecates? | The expensive part of car insurance is the liability part: the amount of damage you are statistically likely to cause to others doesn't change because your car is older. | 4 |
8fnii9 | Physics | Why is it ok to watch a sunrise/sunset but its not okay to look directly at the sun? | It's still probably not considered safe at sunset FYI. It's just not as immediately harmful. That's why even during an eclipse when the sun is 95% covered, it's considered unsafe to look at it. | 2 |
9bvaob | Chemistry | How does shaving gel go from a blue viscous liquid to a foamy thick liquid? | Its basically the same thing as creating a foamy lather from soap, except its been scienced up for convenience. When you lather soap you're working air into mixture, the soap basically just makes it so the interface between the air and the water doesn't take up as much energy so its more stable. With the blue gel, it may have some chemicals in it like isopentane which is just an organic chemical that evaporates just above room temperature, so will expand as you heat it up with your hands. But they will also have glycerin which will hold onto water well and keep it moist and sort of thick, they'll have oils and other chemicals to make the shave smoother and condition your skin along with emulsifiers to allow the water and the oils to mix. They science it up so it maintains a certain thickness and small bubble size as you work air in and heat up the volatile chemicals, but its ultimately the same basic mechanism of creating a foam from soap. | 5 |
cixmqf | Other | Why are some websites/articles always the first to come up when using a search engine when there are so many others? | Each search engine builds a secret algorithm for deciding the top results. They keep it secret so business can’t cheat the system. Usually they try to decide if other people with the same query behaved like they found their answer after visiting a site. Did you immediately click the back button? Or did you stay for ten minutes and then not search again? | 2 |
7gzpgg | Biology | Why do certain bacterial infections (skin infections, strep throat, etc) resolve on their own while others (curable STDs for example) tend to persist for life unless treated with a course of antibiotics? | It's most viruses that stay latent forever. There are some instances of bacteria that live inside you, don't make you sick, but can make other sicks. It's like a landlord that owns a bunch of houses. He doesn't really care who owns the houses, but wants to make sure the tenants are paying rent and not making any mischief. Some viruses (all herpes, others) are like good squatters. They're not supposed to be there, but they keep up appearances from the outside, even though they may be cooking meth on the inside. Viruses have some pretty crazy techniques to evade our immune system. They live inside the cell, and are armed with a host of enzymes and proteins that basically don't alert the immune system to something going on. They disable the alarm system and keep to themselves, so when the police drive by, they see a regular house with the lights on inside and nothing obviously amiss. Some bacteria can do this to an extent, but I'm not really aware of nasty bacteria that don't produce clinical signs, are contagious to other people, and can hangout for any *long* periods of time. You can be infected with a bacteria, not be sick, but still be contagious to other for a long time. These bacteria have characteristics that just makes it so they take a long time before they make you sick. It's not really the same as the way a virus can lay dormant and 'recrudesce' during times of stress and either make you sick all over again, or make you contagious. There's a disease in cows where, if the mother is infected while pregnant at the right time, the fetus develops enough of an immune response to not get aborted, but results in an unthrifty calf that is a major sources of infection for other cows. These animals rarely live beyond a year though. I like immunology and stuff like that, hope this helps. | 2 |
j6fd00 | Other | The concept “straw man” | "Straw man" is a phrase used to describe a certain logical fallacy that one may commit when in a debate/argument. To commit this offense you take someone's position and misrepresent it, then argue against this misrepresentation. For example, perhaps you argue to the teacher that recess is a good addition to the school day--exercise helps work off excess energy and reduces fidgeting, it gives kids a bit of exercise to keep them in shape, and it gives an opportunity for kids to develop their social skills. The teacher then shoots back that if the class spends the whole day at recess then nobody will ever learn anything. The teacher has taken your central claim--that there should be recess--and morphed it into a different one: that recess should be all day. This allows the teacher to defeat this new argument (the straw man) with the obvious counterargument while never touching your original claim. An onlooker may see the teacher's airtight argument and believe that since the teacher has won *one* argument they must have won the argument with you. This makes straw man arguments especially popular in internet and other highly visible debates where the goal is to convince the audience, not so much to convince the person you're arguing against. The more subtly one can misrepresent one's opponent's position the more likely it is that the audience will think you're winning the original argument instead of spinning up a new one. | 5 |
lp533d | Other | How do chain restaurants make sure all their foods taste exactly the same at each and every location? | A lot of restaurants across the US are supplied by the same few food vendors. Sysco comes to mind | 3 |
aj5eoi | Technology | How does the captcha technology work and why sometimes do you have to go through only one test and sometimes 6? | Captcha works by tracking your mouse movements on the screen. It is basically looking for human like interactions, rather than trying to make the questions unanswerable by bots. This is why sometimes it can be as simple as checking the "i'm not a robot" box, and other times, having to complete the same test many times over. | 4 |
anr40s | Technology | What's the difference between CS (Computer Science), CIS (Computer Information Science, and IT (Information Technology? | **Computer Science** - Math behind creating computer programs and systems. **Computer Information SYSTEMS** - This is what businesses called Information Technology in the '70s and '80s. It is a set of things working together to control information on computers. Databases, file servers, etc. **Information Technology** - Basically the same as computer information systems. The technology we use to process information from fax machines to smartphones. | 23 |
b2uy8h | Physics | How does naturally occurring radioactivity differ from the one in power plants? To power a nuclear power plant you need uranium right? So when we mine Uranium, how is the area around the mine affected? Does the place look like a mini Chernobyl, but on a small scale? Is the environment at all affected by naturally occurring radioactivity? | Natural Uranium is pretty harmless, because it is only very very weakly radioactive. You see, the longer the half-time of a radioactive Isotope is, the weaker the intensity of the radiation is. And since anything that we dig up from the ground has been ther for billions of years, it must have an extremely long half-time, otherwise it would have decayed a long time ago. So, Uranium is quite safe to handle, and even if you eat it, you would die from its toxic effect (it IS a heavy metal, after all) long before the radiation would become a problem. You could even hold a uranium rod that goes into a nuclear reactor with your bare hands... & #x200B; ...but only BEFORE it goes in there. Because once it comes out again, some of the uranium has decayed into lots of other things, including shorter-lived (and therefore MUCH more dangerous) radioactive isotopes like Caesium or Iodine. Thouch one of these rods when they are fresh out of the reactor, and you probably wont need a doctor, rather a priest. Those are the things that make nuclear accidents or nuclear fallout so dangerous. & #x200B; So, in short, Uranium itself is pretty safe. The other stuff that it gets split into in power plants and bombs are dangerous. & #x200B; Also, for your last question: Natural radiation affects the environment just like artificial radiation, there is not really a difference. Its just that natural radiation levels are low enough in most cases that we dont really care about them. Should we evacuate whole states because the naturally ocurring Radon gas there causes slightly higher cancer rates? Most people would say no. | 4 |
ixp9jg | Other | how is comic sans design murder? | It isn't - it is all about context. If you want to have comic sans on the packaging of a child's toy, it is completely acceptable. Having comic sans as your font at your gradma's funeral is not acceptable. Most of the times people make fun of comic sans, they are actually making fun of comic sans being used in situations where an other font would be more appropriate. | 2 |
6hfgph | Biology | Why can some people only sleep on their back, and others only on their front or side? | Shape of their spine. People's backs are always changing shape, especially as they get older. When you're a kid you can sleep any which way. Then you experience life and your back gets beat up and you find only one way works best. My sister in law is a physiotherapist. I used to only sleep on my back. Now, with a bunch of exercises and stretches she has given me, I can sleep on both sides and back. This answer is not the whole truth, and I am not a professional sleep scientist or anything. | 23 |
bj7qxp | Other | How fish ended up in unplanted ponds and small lakes with no other water access. | In some cases certain water birds will unknowingly carry fish eggs from one body of water to another | 3 |
n3l266 | Earth Science | If only a small percent of the Earth's water is drinkable, will we ever run out of drinking water? | Yes. If we continue to over-extract for mining, inefficient agriculture and so on while the population continues to grow, eventually there will not be enough to go around. | 3 |
g29knw | Repost | So how does the the human brain ignore the second the? | We don't actually read every word in a sentence. Our brains pick up the patterns and fill in the blanks as we skim along the text, which greatly increases our reading speed while doing very little to reduce comprehension. We do it with just about all sensory input, as well. We blank out while driving but still reach our destinations with no incidents, we tune out smells pretty quickly (no matter how bad the smell is), we tune out physical sensations (you're now aware of how your tongue is resting in your mouth, also you're breathing manually), we hit that autopilot button at work and just coast through it while thinking about the grocery shopping, etc. It's probably an evolutionary trait that evolved from a need to be vigilant against **unique sensory input**, like sudden movements and noticing things that aren't supposed to be there. We're good at recognizing patterns, and tune things out to reduce overall taxation from sensory inputs so we can instead focus on novel inputs. & #x200B; Small edit: I'm an English tutor, and one of the practices we use to catch those kinds of mistakes is to read the whole text backward. Doing this tricks the brain into not recognizing the speech patterns and causes it to focus on each word. | 12 |
k1r4f4 | Physics | What actually IS plasma? And how can it be in the sun but also be in TV's? | Plasma is a mixture of ionized (positively charged) gas and electrons (negatively charged). In plasma TVs the gas is neon and xenon. In the sun, the gas is hydrogen. In a plasma TV, the plasma is stored in tiny chambers. A plasma TV produces visible color by forcing all of the gas ions to one side of a tiny chamber using an electric field (similar to a magnet). When gas ions are forced together, they release energy in the form of ultraviolet light. Ultraviolet light is converted into a color dot (pixel) of visible light by chemicals that coats each plasma chamber called phosphors. | 4 |
7r29lu | Chemistry | How is magnesium, an easily flammable metal used in flares, used to make products such as car parts and computer casings? Wouldn't it be inherently unsafe to make things from a metal that burns with an extremely hot, hard-to-extinguish flame? | URL_0 For reference, here's an accident involving a car with a high-magnesium-content alloy bodywork. However, nowadays, alloys are much safer. | 13 |
6w5tvk | Biology | Why is the skin under our fingernails so sensitive? What purpose does it serve? | In general, all pain serves a single purpose; it prevents us from letting our bodies get damaged. Under fingernails are particularly prone to getting infected. Imagine a cave man 150,000 years ago. He finds it fashionable to stick pine needles under his fingernails, so it looks like he has claws or some shit. Nature needs some way to tell him not to do this. BOOM, pain. | 11 |
6lm3bc | Chemistry | If I burn 1kg of paper in a closed environment, will this environment be as heavy as before? If yes, why/how? | Yes, if by heavy you mean will it have the same amount of matter/energy. This is because burning is a chemical reaction that breaks the bonds between some atoms and creates new bonds with others. This produces heat and light, but doesn't change the number of atoms from beginning to end. | 5 |
ipozyu | Economics | how do taxes work? | Governments need money to function. There are two major ways they get money...they can ask for money when the government does something specific for you, like when you pay for your driver's license or a passport...those are called fees. Or they can take a share out of a transaction you have with someone else (not the government)...those are called taxes. There are \*lots\* of different kinds of taxes but they all come down to a charge that the government puts on money moving around in order to fund the government. Common taxes: Income tax: the government takes a portion of your paycheque. This can be a fixed % or a "sliding scale"...x% of your first $20,000, y% of your next $40,000, etc. Canada uses the latter system. Sales tax: the government takes a portion of the cost of things you buy. A pencil might be $1.00 and the government charges 5% tax, so you pay $1.05. The merchant gets $1, the government gets $0.05. There can be multiple versions of this at the same time...Canada is messy because you have some provinces on harmonized sales tax and some on GST (federal) + PST (provincial). In the US you frequently see simultaneous state, county, and city sales taxes (the US has no federal sales tax). Property tax: the government figures out what your property (land + house) is worth and charges a % of that per year. If you rent, your landlord pays this and it's included in your rent. Inheritance tax: when somebody dies and wills their stuff to you, the government assesses how much it's worth and charges you some %. This is basically like sales tax, only against a gift. Capital gains tax: If you buy something that lasts (house, stocks, etc.) then later sell it for more money, the government gets a % of what you gained. This is basically just income tax for a specific situation. All governments need to take in enough in taxes to pay for what they're doing, otherwise they go into debt. That may or may not be good, depends on the exact situation, but taxes are how most governments fund the vast majority of their operations. Different countries and provinces and states and territories use different mixes of taxes to achieve the $ they need but they all need income from somewhere. Beware anytime someone says "By my state has no sales tax!" or something like that...it just means they've got higher taxes somewhere else. | 1 |
elpzo0 | Engineering | What is the purpose of the black dots on the edge of the windows of cars and trains? | So though all of these answers have some truth to them they are not completely correct. The black stuff is called frit, and it "fades" from heavy at the edge to light due to the tempering process. If it were a solid color it would heat the edge too fast and shatter in the oven. The purpose is for the adhesive to have something to adhere to, and hide the glue edge for a more finished look. I used to run the tempering oven that made windshields and we had to "print" the frit on in a very specific way to prevent breakage while tempering. | 6 |
cokat1 | Culture | Why does everyone use the AD and BC years even if they don't follow Christianity? I feel genuinely dumb for asking but I'm not sure where else I can ask lmao | IIRC, Christians were very influential (and still are) when a standard dating system was established. As such, non-christians had to choose between using the standard AD/BC system or inventing their own non-standard system and causing a lot of confusion. Some people tried the latter, but eventually pretty much everybody gave in, and now the system is so normal that it would cause an awful lot of confusion and complaining if we tried to change. | 4 |
64gx4f | Culture | What are the philosophical differences between transsexual and Transracial? Why is transsexual the only one accepted? Why are transrace people not accepted by any communities? | My guess? Race and sex are very different. There are many scientific studies suggesting that there are such things as "men's brains" and "women's brains" but no such studies exist for black brains, Asian brains etc. the only evidence that might point to this is mostly considered to be pseudoscience, and is used by super far authoritarian right wingers to justify segregation | 2 |
cz8dy0 | Chemistry | why is the Atlantic Ocean so dark and dirty looking on the US east coast, but so crystal clear throughout the Caribbean? | More rivers in coastal US discharge dark water into the ocean and mix close to shore. Not so much in the islands. | 26 |
byj8e7 | Economics | What’s is the difference between a sales tax and VAT (value added tax) ELI5: A politician in the UK has just said that he wants to remove the VAT system and replace with a new sales tax. What is the difference between the two and what would be the benefit of scrapping VAT for a sales tax? | There’s a lot of conflicting information on here. I run a VAT registered business and this is how it works. Goods: Transaction 1: I buy a phone for £100 plus 20% VAT of £20. I pay the supplier £120. The supplier pays £20 to the government. I am a VAT registered business and the phone is purely for business use so I claim the entire £20 back from the government. The government is now back at £0. Transaction 2: I sell the phone to another VAT registered business for £200 plus 20% VAT of £40. They pay me £240. I give the government £40. They claim £40 from the government. The government is now back at £0. Transaction 3: The company that bought the phone from me sell it to a consumer for £400 plus 20% VAT of £480. The consumer pays £480. The company gives the government £80. The consumer can’t claim anything back from the government. The government is now a total of £80 up. END This is silly because £140 worth of tax has been moved about when really it was only the end £80 that actually needed paying. | 7 |
5uxpbp | Biology | Why do we usually only breath through one nostril at a time? | Your body always make one of the nostrils less efficient than the other, because some smells take longer for your nose to sense them. That way you can sense the "quick to sense" smells and the "slow to sense" at the same time. Your body also keeps swapping this task between nostrils so that they both get to do both and be happy and fullfilled. But if you have rhinitis, a flu or some other issue with your nose, this might mean the less efficient nostril won't work at all. This is not how it is supposed to be and maybe a doctor can help you fix it. | 3 |
f61429 | Physics | Why does sleeping in a car feel different than normal sleep? When i fall asleep on car trips it kinda of feels like I’m asleep but Concious at the same time. I can hear conversations, music, etc. why does this happen? | In general, sleeping somewhere unfamiliar to your regular 'bedroom' (including hotels, cars etc.) your brain only switches half off. The other half is alert to potential danger. Over time your brain decides your new 'bedroom' is safe enough to switch off the other half of your brain and you can sleep normally. | 11 |
5thkw0 | Other | Why can receipt printers only use thermal paper? What's the difference between receipt printers and regular printers? | Receipt printers use thermal paper because it simplifies replacement and means that you only have to replace paper. Your local 7-11 can't bother with having an IT staff to maintain the devices. Thermal paper simplifies the process. | 3 |
877fot | Economics | Why aren't we able to stream content anywhere in the world? Is there an actual technical reason for it or is it just discrimination? | It's most commonly a legal rather than technical issue. In the early days of media, it was really expensive and complicated to do anything internationally. If an American company wanted to show an American movie in Japan, they had to either print a bunch of reels of film in the United States and then ship them to people in Japan and have them somehow get to various theaters, or they had to ship a set of master reels to Japan and have a local film duplication company duplicate them and then send those reels to theaters. All of that had to be done when nobody in the company had ever been to Japan, almost nobody spoke Japanese, nobody knew what kinds of movies the local market wanted, nobody knew the local media and censorship laws, etc. And then that process had to be repeated for every country they wanted to distribute their media in. The result of that was that instead of having the company that created the media try to figure all that out, what they'd do is sell an exclusive license to a distributor in those countries, and then it was up to the distributor to figure out what the right way to deal with everything was. Sometimes those agreements were one-offs, but sometimes relationships were built up with distributors and they'd just routinely sell them licenses for everything they made, maybe for a share of the profits or maybe for a fixed rate, whatever deal they hammered out. This worked out really well then, but nowadays these agreements end up making things complicated. If American Movies Corp. has an agreement with Japanese Movies Ltd. to be their exclusive distributor in Japan, then they can't distribute their own movies to Japanese people. And Japanese Movies Ltd is going to sue American Movies Corp. if they sell a license to Netflix that makes those movies available in Japan. So now, when American Movies Corp. is talking to Netflix about distributing their movies on the Internet, they have to tell them that the license they're giving them doesn't apply to Japan, or the UK, or France, or 17 other countries where they sold off their rights to a local distributor. That means when you ask Netflix to play an American Movies Corp. movie while in Japan, it won't come up, because they don't have a license to play it there. This is partly why it's so much easier for companies like Netflix or Amazon creating original content. They don't have these existing distribution arrangements, they still have global rights to everything they make, so they can just distribute it globally and everyone is happy. | 1 |
8qj1iw | Chemistry | Why when the bathroom mirror fogs up does it “defog” itself from bottom to top and not top to bottom? | The hot air in the bathroom is hot because it's been heated by the hot water in the shower, so it's hot but also very heavily laden with moisture. When the air hits the coldness of the glass it cools and (opposite to the other answer) cant hold as much water so the water drops out on the mirror. The hot wet air from the shower and the cold dry air from the house form layers, which you can't see with your eyes, but as the hot air escapes around the ceilings of the house the cold dry air rises up the mirror. The moisture on the mirror evaporates only when the cold dry air is on it, so the fog appears to clear from the bottom up. | 4 |
gyl3dv | Biology | What happens if a perfectly healthy person takes insulin? | Basically the same situation as if a diabetic took too much insulin as opposed to what was needed: they run the risk of inducing a low blood sugar situation (hypoglycemia), which may be hazardous. | 1 |
8o80lx | Physics | the theory of "broken symmetry" by P. W. Anderson Hi, currently I am having some difficulties understanding the "broke symmetry" theory by P. W. Anderson; Could somebody help me to understand it? From [Anderson's "More is different" article]( URL_1 ) the theory of broken symmetry is: > a general theory of just how this shift from quantitative to qualitative differentiation takes place Where "this shift from quantitative to qualitative differentiation" is the [emergent behavior]( URL_2 ) of complex systems. References: * [Anderson's "More is different" article]( URL_1 ) where he explains the theory * [Wikipedia page of symmetry breaking]( URL_0 ) * [Wikipedia page of emergence]( URL_2 ) | To understand this, you first got to know what we call Curie's Principle. It's a principle we get From Pierre Curie and his brother, and that has to do with the symmetry of causes and consequences. The principle simply states that we can see the symmetry of the causes in the consequences. For example, imagine you get a magnet under a uniform magnetic field pointed up in the z direction. If you take simple Newton's mechanics, you have two forces on the magnet, one up from the field, and one down, due to gravity. If you take any rotation around the z axis, no matter how small, the system is invariant. It means you have an axial symmetry around this axis. With Curie's principle, you then know that when applying the field, the effect will also have and axial symmetry around z. (So it can only go up or down, it can't go right or left). No, take a pencil, and put it vertically on the table. You still have an axial symmetry, but when you release the pencil, it will fall and lay horizontally on the table. (We assume that it doesn't roll or do any other thing, i.e. the tip of the pencil is at the same place as where it started) When you started, you were able to do any rotation around the z axis and get the same system. But after releasing the pencil, when it lay down on the table, you can't take any rotation around the axis (only 2*pi). - > you don't have the same symmetry. This is the breaking of symmetry. But you might argue that it doesn't respect Curie's principle in that case. But here is the little trick, if you do the experience infinitely many times, the repartition on the pencil on the table will makes a circle, so we get the symmetry of the causes in the consequences. | 1 |
a1shf7 | Biology | When removed from adults beavers as babies, those beavers will still try to create dams as adults. Is there anything humans will do on instinct even if not prompted by other human contact? I was prompted by this video to ask this question URL_0 So this rescued beaver just starts building dams because that's what beavers do, Do humans have similar things that we would do without being prompted? Outside of seeking food/water of course. I understand that it is possible that he saw his parents building dams before he was rescued, but I think that he would have built dams regardless because of instincts. | Because of how altricial we are (we're totally helpless as babies, and stay that way for years) it seems that humans don't have a lot of complex instinctual behaviors like that. Our life strategy is to stick around our parents and learn how to be adults from them, instead. | 3 |
nuttsb | Physics | If you trap a beam of light inside a perfect mirror sphere, where does it go? | Yes, but the reality is that real mirrors aren't perfect, so if you do that for a real mirror sphere, it will end up eventually being absorbed by the mirror and turned to heat. Each bounce will cost around 1% of the light being turned to heat even with extremely good reflectors. Also, you'd never be able to view it, because any device put in to view it would also absorb photons. | 2 |
cd75jb | Technology | Why are some items recyclable while other seemingly identical items are not? For example, I have a plastic milk jug that has a recyclable stamp on it, while I have a vinegar jug that does not. | The simple answer is they are made of different types of plastic. Vinegar is acidic so it may use a different plastic in order to maintain the integrity of the bottle compared to milk which is way more neutral. | 2 |
asim5z | Physics | What is plasma? (as a state of matter) I recently realized that plasma is A LOT more common than I thought. Still can't wrap my mind around what it is.. | Matter in solid, liquid or gaseous form is made up of atoms. Atoms are made up of protons and electrons, and nearly always neutrons as well. It's useful but not entirely accurate to think of protons and neutrons clumped together at the center of each atom (the nucleus) and the electrons whizzing around the center in a type of orbit. In a plasma, the electrons are "free" - they separate from the rest of the atom and travel more or less freely. This bestows certain properties on plasma that the same substance in a solid, liquid or gaseous form may not have. Plasma is a higher-energy state than gas, which is higher than liquid, which is higher than solid. So to take a substance from the solid phase to the liquid phase to the gaseous phase, just keep adding energy. The element mercury is solid at common room temperature, but if you add some heat, it becomes liquid. Add more heat, and it becomes gaseous. At each of these phases however, a mercury atom consists of 80 protons and 80 electrons (plus 121 neutrons), all more or less bundled together. The difference in each phase is that these bundles of protons, neutrons and electrons, while staying bundled, zip around faster on average than in the prior phase. Keep adding heat (energy), and the electrons eventually separate from the atoms and while you'll still find clumps of 80 protons and 121 neutrons bundled together, electrons whiz about without regard to what used to be electron orbits around each atom. This is a plasma. As They Might Be Giants succinctly put it, "Plasma, electrons are free. Plasma, a forth state of matter. Not liquid, not solid, not gas." (TMBG, The Sun is a Miasma of Incandescent Plasma) | 1 |
9ztqbn | Physics | If the universe started as a 0 dimensional singularity, why did it expand into 3 dimensions? | I might help to think of dimensions not just as physical dimensions but as *features*. That is, ways of distinguishing one element of a set from another element of the set. When you only have one element of the set, you don't need any features (dimensions) because you have no need to distinguish two elements from one another. As you add elements to the set, you need more dimensions if you want to fully describe the set. So a singular universe *must* have zero dimensions. The question then becomes how many dimensions (features) do you need to describe a non-singular universe. As it turns out, less than two spatial dimensions is too 'restrictive' to create the interactions necessary for an observer (us) to exist. On the other hand, more than three spatial dimensions is too 'permissive' for that observer to form. The same sort of argument can be used to justify the single time dimension. You can get more details on this: URL_0 So basically you can keep rolling the dice. You start with a singularity. You add additional elements to the set. If you happen to roll up 3 spatial + 1 time dimension, you can develop a universe with observers to wonder at why 3 spatial + 1 time dimension exists. If you don't, then no observers and eventually you end up back at a singularity to try again. | 1 |
ihg0id | Other | Why the English language has Uppercase & Lowercase alphabets? I am trying to teach my 4-year-old son how to write and read. However, I just realise why do we have uppercases and lowercases in English writing. P.S. I am from India. | The same reason why we have punctuation. Capital letters signify certain things. For one, it tells the reader when the start of a sentence is. Native readers find it easier. Secondly, it shows the difference between proper nouns and normal things. EG: I had lunch at the garden. (You had lunch at any old garden) I had lunch at The Garden. (You had lunch at a restaurant called The Garden). Thirdly, in advertisements and signs, ALL CAPITAL LETTERS CATCH YOUR ATTENTION. Online, it signifies shouting. It can also be used for EMPHASIS. We are not 100% sure why the letter I is capitalised when it comes to referring to the self. It has been lost to time. But that's what languages do. In writing, certain lowercase letters look alike if people have bad handwriting. For example o and a. m and n in a row. h and n. But uppercase letters are easier to pick apart. This is why when filling out forms, you are encouraged to write in uppercase. So there aren't THAT many reasons (see the emphasis?) for capital letters to exist, but they're there. | 4 |
bal9k3 | Engineering | Why do modern vehicles still use a dipstick to check the oil level instead of an automatic gauge? | A visual inspection of the oil condition is of great value. You can see if the oil looks dirty or if it's still relatively clean, and for instance, if your oil is frothy, you have antifreeze in your oil and have a serious problem. | 3 |
ir8jr4 | Other | Why does our brain go blank during exams or freeze in certain situations? What is the process behind this? | Theres a thing in psychology called the four stages of competence, which go like this: 1. Unconcious incompetence: You're just flailing around, and don't really understand enough to know why you're struggling. 2. Conscious incompetence: You're still not very good, but you're starting to understand where your deficiencies are and how to make real progress improving. 3. Conscious competence: You've learned everything you need to know to do really well, but you still need to focus to do it. 4. Unconscious competence: The skills have become reflexive, to the point that all you need to do is identify the task and your body will just go to work without the conscious part of your mind needing to get involved closely. The problem is that during high-stress situations like an exam or a performance, it can be hard to relax and let your subconscious get to work. It's almost like having a subordinate you can just tell to do something for your. This is a problem, because once you reach unconscious competence you can get out of practice at actually thinking through the process, which means if you do start consciously thinking about it you won't be able to do as well as your subconscious. If you want a way to see this without the stress of choking on a test, try walking across a room, but pay attention to every individual movement that your feet, legs, and toes have to do. You'll find that you're slower, clumsier, and have worse balance until you stop paying attention and just let yourself go back to walking normally. This is because walking is about as deep into unconscious competence as you can get, to the point that almost nobody more than a few years old thinks about it at all. | 2 |
84eqw3 | Mathematics | Why do some countries teach multiplication tables to x12, and others teach to x10? | Germany here. We don't do 12s. There is no reason for us as we are thoroughly metricised. ;) Only countries that still use non-metric units of measurement might need to learn anything besides multiplication to the base of 10. (Only UK and US come to mind, but there are probably more) | 3 |
5smzsr | Other | Why is Betsy Devos considered unqualified? Genuine question, i stopped paying attention to politics | She is an education secretary with no experience working in education. No formal education, no professional experience. It's like assigning someone to run the military who has never fired a gun. | 3 |
k9vwbs | Other | Why can't the government just tell you how much you owe in taxes so you can lay that amount? | In addition to the TurboTax lobby which has been mentioned by others, you also have to consider the influence of small government activists in America. The Grover Norquists of the world fight against things like automatic filing because they want people to have difficult interactions with the government. They see the frustrating and anxiety inducing process we have as a feature, not a bug. If the government makes filing taxes easy, people might start asking "what else can government do well?" There is a huge propaganda machine in this country spreading the idea that government is always bad at whatever it needs to do. We have a political party that actively prevents the government from working well and then uses this disfunction as an excuse to cut funding for the needy, slash regulations that keep water and air clean, and pass tax cuts for the most wealthy. | 12 |
77cdvv | Other | What protects journalists from being interrogated by the government for information on illegal activity? | Some jurisdictions have specific journalist shield laws that allow a journalist to claim privilege over the sources of information. Some law enforcement agencies, for free speech reasons, have official or unofficial policies that make targeting a journalist difficult outside of certain circumstances (like the journalist is part of the crime). This can also be done as a way of helping police more generally, since it's better for reporters to be able to get stories that alert the police of a danger (there is a factory making drugs) then it is for there to be no story and less understanding of the facts. Some of the details you are asking for (like magnitude) are already going to be in the story. But the real answer is that usually it's not worth very much to go after journalists like this. The drug facility might already have moved, or might have been staged in the first place. The subject of the reporting might not have allowed the journalist certain information or access, beyond what is already reported. And, even if they are holding information in confidence, having a hostile witness might not be that helpful. | 2 |
734de8 | Biology | What exactly determines that human can live up to 100 years, while other species, animal or plants, living between hours to 1000 years ? Very curious about this, it can't be random | Annoyingly, we don't quite know yet. There are a lot of theories about it, but none of them get things quite right. Its something we've only been able to study for a pretty short time. There were some promising theories at first, but they've since been proven quite wrong. So we're really still in the dark about it. | 2 |
a4juxy | Biology | How does every involuntary movement in our body keeps happening? | Blinking, while it can be done voluntarely, is mostly a reflex handled by your brainstem, you have nerves going from nucleus in the brainstem that control the blink (I think it's the 5th cranial nerve and maybe the 7th, ot sure about the 7th) For your heart, it's different. While you still have nerves from your brainstem controlling your heart rythm, you don't need those nerves for it to work. Your heart is an autonomous organ, as long as it has oxygen and glucose, it will beat. Some cells in your heart can excitate themselves alone and generate an "electric current" that will make your heart contract. People who get heart transplants don't have the brainstem nerves reconnnected to their new heart. People with normal heart have a rate around 70 beat per minute, and it's around 100-110 when you're doing a physical effort. People with transplanted heart have a normal rate of 100 beat per minute, and it's around 120 when they do a physical effort. NB : Not having the nerves isn't that big of a deal, it doesn't impact the heart function, just makes it beat faster. Plus you still have your endocrinous system that release adrenaline/noradrenaline in the blood stream when you do a physical activity, so you can still adapt do physical activity just fine, your heart will still adapt | 2 |
fdwmqc | Biology | How does Hypnosis work? What is it capable of? How is it that people can describe something or someone in great detail when hypnotized which they wouldn't have been able to remember otherwise? What goes on in the brain during Hypnosis? | There is a brain state where there is an very specific pattern of theta waves. That brain state is associated with deep relaxation or "zoning out". What is most interesting is that when you are in that state, you (oversimplifying) have a more direct connection between input and autonomic reaction. In other words, given a stimulus you respond automatically without thought. There are a few different ways to invoke the theta state: * Hypnosis * Mediation/Prayer * This idea of ["Flow"]( URL_0 ) * The idea of "presence" in gaming/VR/etc. This is when you are making movements, etc. without thinking. This was actually my area of research. In the context of hypnosis, there is some thought that being in a theta state may lower your normal defensiveness by creating a stimulus/response loop outside of conscious thought. Thus people lose their inhibitions and do what's suggested. But reaching this state is unlikely during a stage hypnosis show. | 21 |
66zkaf | Chemistry | Why do antidepressants cause suicidal idealization? Just saw a TV commercial for a prescription antidepressant, and they warned that one of the side effects was suicidal ideation. Why? More importantly, isn't that extremely counterintuitive to what they're supposed to prevent? Why was a drug with that kind of risk allowed on the market? Thanks for the info Edit: I mean "ideation" (well, my spell check says that's not a word, but everyone here says otherwise, spell check is going to have to deal with it). Thanks for the correction. | ELI5 edition: Think of depression in the brain as people going into a carnival and passing through turnstyle gates to get in. When you are depressed there arent enough people and the shops in the carnival are sad because they have little incoming money. The antidepressant locks all of the turnstyles initially, so the customers are completely blocked. The shop owners then have no money and start to panic. They think they are done for and think about giving up. Then, one of the turnstyles is opened and there is a crowd of people outside waiting to get in, but the turnstyle can only let in a slow steady stream of customers. The shop owners are now happy. I've been depressed for a long time. I have had my limits tested by every form of antidepressant drug (there are only about 3 that have passed regulation). The field of knowledge is actually quite small so it doesn't take long at all to know your stuff. But I'm going to only cover the SSRI. SSRI: selective serotonin re-uptake inhibitor. This causes the most problems, however it is the most common treatment. It forces more of the hormone serotonin by putting a sort of barrier on your receptors so the supply of serotonin builds up and you have a steadier flow of it supplied to your brain. The problem lies within this barrier on the receptors. In the first stages of a new dose the barrier can form too well and actually block up a large amount of serotonin. No serotonin = increased suicidal thoughts. You can also get resistant to SSRI's. In many folks their dosage increases a couple times a year because the barriers arent strong enough. There is also Serotonin Shock Syndrome, which can be described as having a conscious seizure. It is also potentially fatal. This happens if the SSRI barriers somehow break and the floodgates of serotonin rush into your brain. I have been there, and it's not fun. It occurs more commonly when there is a negative interaction with another psychoactive drug. | 65 |
814az6 | Biology | If we reflected a person (like in mirror), particle by particle, would it be still able to live? In other words, are there any processes in human body that won't work after such reflection? | Mirrored molecules migh become a problem. Many complex organic molecules have mirrored isomeres aka stereoisomeres. Since some biochemistry processes depend on exact shape of molecule, stereoisomeres might work differently - even be poisonous. Now, since mirrored human would have all his molecules mirrored, they should work normally. Also basic food, proteins, carbohydrates and fats, would be processed as usual. But then we have all kinds of vitamins and other complex organics, some of which would not work or even become dangerous. Vitamins could be synthesized in lab, but won't come with food. BTW I remember there was an old sci-fi short story on this topic. > either front to back (that is how a reflection in a mirror works) or any other dimension (e.g. left to right), though I'm not sure if it would make any difference Also yes, that makes no difference. If you imagine three axis vectors (say, point ring finger forward, thumb up and rest to the side), you can rotate them together any way you want and then rotate back in original position. But mirror inverts one of them (any one), and resulting triplet cannot be turned to original position by rotation. | 2 |
5yjbv2 | Technology | How does your browser know what server to connect to when you type out a url? Where is this information stored? | Your browser doesn't know! For the second question: Your browser sends the request to your proxy, which is maintained by your Internet Service Provider (they're the people you pay money to for your internet). Your proxy knows of the existence of a Domain Name System Server (DNS) that it sends the name to. If you want to know where that is: URL_0 This server has a list of names that it translates to an IP address, like 241.10.231.117. Your browser now replaces the request name with this IP. This is stored locally. Fun Fact: You can edit your computer's settings to always map a name to a certain IP. So for instance map URL_1 or URL_2 (those idiots who fill your pages with clickbait ads) to 127.0.0.1 (default name for your own computer) and whenever a webpage tries to connect to them, it will connect to your own computer, get nothing, and leave the space blank! Now the browser will attempt to find 241.10.231.117. It will send the request to the nearest router. The router has a bunch of streetsigns (not a technical term, just an analogy) saying in which direction that is. And eventually you find the right computer for your request. | 1 |
cft1l9 | Technology | How is it possible that games like Spore (the one where you make creatures ect.) are able to have full animations for things that you only just made. i can use the same parts on a creature and have them look wildly different yet it still has a decent animation for its actions. | Afaik there's a simple Skeleton structure with the animations baked into it that is invisible, which controls how the character model works. As an example for how it can work with more than 2 legs, The animation for the legs is copied to each set of legs your model has, and has an offset on when the animation plays so the legs look like they move fluidly. I may be wrong, please correct me if you know better than I do! | 2 |
9njare | Physics | Why does a magnetic field do no work on a stationary particle but yet electric field does work on it? | The electric field (ac) is moving so the stationary particle has motion with respect to the electric field creating work. The magnetic field is stationary and thus is stationary with respect to the stationary particle so no work is done. | 2 |
bdtnuv | Engineering | Why will the rebuilding of the Notre Dame cost millions of dollars? | Well the renovations before the fire were gonna cost around 170 million anyway, so adding more work to that will put the cost up drastically. However I’m not sure how much it would have cost to build it 800 years ago | 3 |
63spov | Economics | The average home cost in Toronto is about $916,000, however the average household income is around $75,000. How are the housing prices so high? and how on earth are people affording them? | A major though hard to quantify reason is that it is very easy for upper-middle and wealthier foreigners (particularly Chinese and Indian in Toronto's case) to purchase property (particularly condos) as investment properties. This skews the market tremendously. Huge swathes of those new condominium buildings are sitting vacant. Try walking on the side streets and back alleys around them and there are practically billboard-sized pieces of plywood covered in those realtor lockboxes (the ones with the keys inside for agents to show the properties) for vacant properties looking to find a renter. There's woefully inadequate government tracking of who is buying what, where they're from, and what it's really being used for, but talking to some realtors and doing some basic lockbox-to-units math paints a pretty clear and consistent picture. Eventually that bubble is going to crash. Don't buy now. | 27 |
eynpfk | Biology | why does your head hurt after crying? | Sadness triggers stress, which causes the body to release hormones such as cortisol. These hormones stimulate neurotransmitters in the brain that cause physical reactions such as crying, headaches, and runny noses. | 1 |
co7b9z | Biology | How do we bleed without tearing a vein? If blood runs in our veins, how come we bleed when we get a (not deep at all) cut? We don't cut our veins (I think) because we would die from that? How can we bleed? | Veins and arteries are the super size sixteen-lane highways of the circulatory system. There are many smaller types, going right down to capillaries, which are the little single track barely-marked-on-a-map roads. If you cut yourself the blood is probably coming from one of these tiny smaller ones. You don't bleed to death because your body generally is very good at plugging these leaks, closing the roads where there's blood being lost. | 10 |
ic678r | Physics | Why are rain clouds darker than normal clouds? Title says it. I know they sometimes aren’t but what causes them to be so dark sometimes? | Rain clouds are full of rain.... the denser they are the less light goes through and they appear darker. This is opposed to light fluffy clouds which are less dense. URL_0 | 1 |
7ej40i | Other | Why did Mao and Stalin kill all those people? | It really depends which "killings" you're referring to. For Mao: - The Chinese civil war was a period of massive instability. People were killed largely as a matter of trying to win that conflict. - Afterwards, the "cultural revolution" and "great leap forward" were respectively attempts to destroy the old imperial Chinese culture and replace it with a new, distinctly modern one, and an attempt to rapidly industrialize and get China on the path back to being a world power again. It's the second category of deaths that I think you're mainly referring to. /u/Absobloodylootely does a good job of explaining a lot of the rationale. One thing I would add is just the answer to "why did that many deaths seem worth risking?". With Stalin, under the purges and holodomor, the motivations were a little more straightforward - he was eliminating enemies. The purges were about political enemies within the state, and the holodomor was about privileging ethnically russian citizens who were seen as more loyal over ethnically ukranian citizens who were seen as less loyal. With Mao, a lot of the people were still ethnically Han Chinese, and a lot were even fairly supportive of him. So why risk their lives? The crucial point is rooted in the ideology resulting from the Chinese [century of humiliation]( URL_0 ) - in a sense, "humiliation" is really too mild a term for it, since western powers invading and occupying china were responsible for death and destruction on a scale that's difficult to even comprehend today. In that century, you had 2 opium wars that flooded the country with drugs, destroying its population and undermining government power, the Taiping rebellion that killed up to 30 million people, The Sino-Japanese wars that killed up to 20 million, the Chinese civil war that killed up to 9 million (though partly overlaps with Sino-Japanese conflicts), the Dungan Revolt that killed up to 12 million, etc... (and that's only counting conflicts with a death toll in the millions during that century). It's not an exaggeration to say that between the 19th and 20th centuries, China saw more people slaughtered than just about any country has ever seen in human history, mostly in conflicts involving foreign powers. Besides which, that was starting from a perspective in the 18th century where Chinese culture considered itself the leading nation on earth. So the reaction by Mao and CCP leadership - having a willingness to sacrifice even massive numbers of people to ensure that history never, ever repeats itself, and to have China re-establish its position within the world system, the extreme measures at least make a bit more sense. Also, considering the methods Mao used - it was precisely the same mass mobilization and political rallying that killed millions in the Great Leap Forward that previously helped the CCP prevail in the Chinese civil war. Essentially, he was trying to industrialize using the tactics of a guerrilla uprising. Yes, Mao was absolutely wrong in the direction he took to achieve those ends in the Great Leap Forward, but given the country's history for the preceding century, and the past success of those same leadership methods, there's a reason people were willing to follow along that far. That certainly doesn't excuse the abuses by any means, but at least it puts them into some kind of context. | 5 |
72q74x | Chemistry | What are the actual negative effects of drugs like ecstasy and Molly? Most websites I've found just say that they will cause increased body temperature and dehydration, but I've heard others warn that they can "melt your brain." Are there any studies or evidence to show how bad they actually are for you? | I remember when I got into it 10 years ago they didn't have any legitimate studies or pages highlighting the negative. To tell you the long term effects, I have chronic depression, suicidal ideation (and one attempt on my life thus far that miraculously didn't work), pychosis, mood swings, and severe anxiety. Short term? Super fucking bad psychosis. I've run the gamut from aliens reading my mind to my friend being Satan. These will persist after the drug wears off, too. This shit basically gave me schizoaffective disorder and now I pop psych meds like candy to stay as functional as I can | 4 |
5t4m8g | Biology | Why do you sometimes feel nauseous/queasy when you're extremely hungry? It seems really weird that at a moment when your stomach is almost (if not totally) empty, that you can feel like you're about to throw up. What's going on there? | Two main reasons: * your blood sugar has dropped enough to cause a mild case of hypoglycemia, which can be associated with nausea, shakiness, lightheadedness * an excess of stomach acids is irritating the lining of your stomach and causing inflammation. This happens in people who have issues with their stomach emptying properly especially. | 3 |
ik53bq | Biology | Why and how do some hairs "know" when to stop growing (e.g. eyebrows, arms, eyelashes) while others (e.g. scalp, beard) doesn't seem to? Is it that they don't know or the "threshold" is so long that we don't get to see it very often? | Ugh wait till 50. They ALL forget to stop growing and also they decide to grow in areas that have no business having hair in the first place =...( | 10 |
bqd7h6 | Biology | How boxers are able to remain standing yet are unable to defend themselves during a boxing match until the ref calls off the fight. How are some boxers able to just stand there and take the beating without falling or being knocked unconscious yet don’t have the insight to defend themselves? Do their minds go blank? | Your brain has layers. Deeper into your brain you find much older structures which deal with fundamental matters like breathing and standing up. Higher up in your brain are more modern structures which deal with more proactive and abstract thought processes. When your brain is stressed it shuts down or reduces thinking in those outermost lobes and retreats into its reptile hindbrain. Or to put it more simply the part of your brain that controls coming up with and implementing a defence strategy shuts down long before the part that's just "remember to stand" | 2 |
kezhgc | Other | Why do videos seem shorter the second time you watch them? | Similar to when you're travelling a route for the first time, and then when you do it again for a second time, it feels quicker. Your brain needs reference points to contextualise things; it's notoriously bad at thinking about things without them - both because it's not quite as good at 'abstract' things (take for instance the difference between a million and a billion - brains are just like 'meh' about this, until you tell them that a million seconds is 12 days, and a billion seconds is 31 years), but also because when knowledge of variables (such as time) are missing, then the equation effectively can't be solved, or at best can only be guessed at. With videos you've seen before, you have a timeline of expectation you can place yourself in, so you get more context about progress. With videos you haven't watched, there is no context until you've finished the video and can assess it retrospectively. | 2 |
7he5h1 | Physics | How do the foam cutouts in a recording studio mute out sound? | They don't mute the sound they absorb it. Picture this: throw a golf ball as hard as you can into a tiny room with concrete walls, floor, and ceiling. What did that golf ball do? Now cover the walls, floor, and ceiling with thick feather pillows and throw that golf ball. The golf ball represents the sound travel. | 3 |
81y6vq | Biology | Why do primates such as gorillas, baboons, and chimps (especially those in a zoo) retain so much muscle and strength doing little to no muscle building activities. Yet, humans must consistently work out properly to retain muscle and strength? | A lot of the replies are geared towards dexterity and such, but the main reason is actually endurance. We evolved as endurance hunters. That's also why we can do without sleep better than most animals. Before we used tools, we literally hunted by stalking things until they passed out from exhaustion. Both a little badass and a little creepy. | 17 |
6jogng | Biology | How do cows produce milk throughout the entire year since most mammals stop after a certain period of time after giving birth? | Most mammals lactate as long as their young nurses. When nursing stops, lactation stops. When dairy farmers continue to milk them, they keep producing milk. | 6 |
g1ru6v | Economics | Is there someone profiting off of my student loan payments? | When someone puts up the money to lend to you in the form of a student loan, they expect a return on their investment. People will not take on risk in the form of lending capital without a promised return on investment. It’s not capitalism it’s common sense. In reality there system is much more complex through banks taking peoples money (checking, saving accounts) and lending that money out in order to pay people interest. You have to remember that banks don’t just have piles of cash, they invest what you give them and use the returns on those investments to profit and also give you a return on your savings and even checking deposits. So yes someone “profits” but that “profit” is a return on investment, a way to incentivize people to lend money to students, and enable the student loan system to work. | 2 |
9njncy | Culture | With the push for equality across the board, wouldn't it make sense to do away with asking race on forms and allow for the best suited to be selected for positions and other such things, or is there a reason to keep it? | Equality isn't achieved by pretending that it exists. There are structural problems for people of non-white races that need to be dismantled first. Just trying to erase a label without erasing the difference the label made in the first place doesn't solve the issue. | 3 |
70kghh | Other | How does hypnosis work? Can you be hypnotized to act against your will? I am searching the web as I watched a movie with hypnosis and I always thought that hypnosis was somewhat a myth. *Can you be hypnotized for real, what happens, how does it work?* *Can you be hypnotized to fall asleep for instance, when hearing a certain noise?* *How does one feel when is in state of hypnosis, can you leave the hypnosis on your will, without hearing whatever sound does the hypnotizer decides?* Thanks! | There's honestly a lot of debate about it, but I personally think it's likely mostly (perhaps entirely) people just playing along and doing what they think they are supposed to do. Stage show, up in front of the crowd...it would feel silly to not follow along. So people do what they're expected to do and get a cheer. If it really worked, you would see governments and spy agencies using it as a weapon. But there are real examples that something sorta similar happens in nature, see tonic immobility with sharks, chickens, some lizards, etc. | 4 |
a6gcbu | Culture | How can a Federal judge in Texas rule Obamacare's individual mandate as unconstitutional when the Supreme Court decided it fell under Congress' taxing power in 2012? | Before a judge makes a decision, they usually have two arguments (one from each side). Sometimes the arguments are faulty, incorrect in some precise legal way. These are the easy cases. The interesting cases, like the Obamacare case you cite, have two arguments that do not have a clear legal fault. In these cases, the judge has to decide which case is stronger. It's a relative judgement, and therefore subjective. Subjective rulings are often appealed. In a subjective situation only a ruling by the SCOTUS sets a definitive answer, a precedent that future courts will apply. In this case, the SCOTUS went the other way, but that's how the system is supposed to work. When the SCOTUS agrees, they often refuse to hear the case, essentially saying the preceding judge's decision was clear enough that they don't need to reconsider the arguments. | 1 |
69w72r | Culture | How is India able to function as a democracy when almost 30% of the population is illiterate? It seems like this would make it difficult to use ballots and access translations, which seems particularly important given India's huge language diversity. How can I find a candidate to support if I have no idea what they're saying? How can I vote if I can't read his or her name? Thanks! | Hi, I’m a Westerner living in India. The answer is: India doesn’t really have a functioning democracy. Elections are bought. There is corruption on all levels. A simple example: a few months a go, there were elections in my state of Punjab. All the political parties distributed money to their candidates so that they would have village leaders organize parties in their name. India is very tribal, so village people all just vote for the candidate they receive most attention from. No-one reads the programs. All the candidates make lofty promises that everyone should know they can’t keep. | 5 |
7gnoqb | Chemistry | How does charcoal clean your face? Recently, I've been seeing a lot of advertisements touting "activated charcoal", and talking about how it will "attract the dirt from your pores". How does this work? Does it even work? and how is it any different than rubbing charcoal on your face? | Charcoal generally has the property of having lots of pores that are approximately the correct size for medium-sized organic molecules to enter and become trapped. Activated carbon/charcoal has been produced in a way to maximize those pores, making it better at that process. If you're making charcoal for fuel, you don't care about the ability to adsorb oils or contaminants. If you're making it for a water filter, you don't care how it burns, you want to maximize pores and surface area. | 3 |
iczr1i | Biology | why do our bodies crave unhealthy fattening junk/comfort food at night? | Are you also a night person? And are you skip breakfast person? | 10 |
8pd8em | Other | What exactly is a "forced march"? Also, how does it actually work? | In a normal military technique for getting infantry somewhere more quickly, at the cost of fatigue, reducing fighting ability, and higher casualties. They basically order the troops to walk farther and/or faster than they normally would, and threaten punishment for insubordination (or worse) if they don't. Plus, if you have all the food, shelter and bullets and are somewhere people are trying to kill you, your soldiers have a pretty big incentive to keep up. You are typically going to also make allowances for more people getting hurt and find a way to transport them or safely leave them behind. Some forced marches in history have been much more brutal than that, unwilling, untrained, unequipped conscripts under threat of being shot if they don't keep up. | 1 |
abfhrg | Other | Is there an official name for beep boop music? | look up 8-bit music. also, this would probably be better to ask in r/nostupidquestions. it's a general question subreddit | 2 |
5ldlgf | Other | Why were slaves treated so badly? | I'd like to hear an informed answer. If I'm not mistaken, it was less likely for a slave to be treated like shit (as we have seen portrayed in popular media). I would assume that slaves developed more or less entire communities, generation after generation, and had a rather symbiotic relationship with the plantation owning family. Would love to hear some information on this. | 8 |
5rclvd | Other | The difference between an Officer and an Enlisted person in the army | A commissioned officer (lieutenant, captain, colonel, general, etc...) is a member of the military that derives his or her authority from a commission (formal appointment) issued to him or her by the head of state. In other words, he or she derives his or her authority from the state. Commissioned officers are generally in positions of management and leadership rather than positions of specialisation. However, air forces are often an exception to this. Non-commissioned officers are enlisted personnel (corporal, sergeant, warrant officer, etc...) that have obtained a position of leadership or authority through experience and promotion through the enlisted ranks. However, even the most senior NCO is inferior in rank to the most junior CO. In practice, commissioned officers give general orders to non-commissioned officers, who in turn give specific orders to junior enlisted personnel under their command in order to facilitate the execution of the general orders that they were given. | 3 |
5qglv4 | Repost | Wouldn't a 20% tariff on Mexican products ultimately end with US citizens paying for the wall? | More than beer comes from there, my friend. A significant amount of food produce is grown in Mexico. And tes, such a tariff would make everyday purchases go significantly up for every American. And yes, Americans would be paying for the wall. | 5 |
9uolg9 | Other | Why do dentist say not to brush your teeth with hard pressure as it is bad for enamel, yet they can drag a metal tool along your teeth? | All of the above comments are correct, but also worth noting is that dentists use the explorer or probe on tooth surfaces that are already carious, or on fillings. You can drag an explorer across enamel to check for irregularities, but you never apply too much pressure to damage it. | 2 |
9cr5qq | Biology | Why does chloroform knock you out when you inhale it? | It's a sedative, they reduce activity in your central nervous system, putting you in an effectively sleep-like state. | 3 |
5x0cz4 | Biology | why do men feel tired/sleepy after orgasm or ejaculating? i think ive seen it on a documentary before, something about hormones or chemicals released during orgasm but why? is there a biological reason why men's bodies would feel tired or sleepy after orgasm? also, i think its been answered here before but the answers have been deleted. URL_0 | IIRC from my anatomy class, it also has to do with your sympathetic and parasympathetic nervous systems. The sympathetic (fight/flight) is responsible for getting an erection and the parasympathetic (rest/digest) is what actually causes you to orgasm. People in combat experience what is called a parasympathetic backlash, which basically means you crash after you're done fighting. If your forces on a hill get over run, then you have a good chance of taking the hill back if you can rally the troops and counter attack due to the enemy experiencing this backlash, that's why soldiers have to stay busy after an engagement. So sex is very similar to combat/fighting. You're up, you're rocking, you're down, you're done. | 4 |
a94n8z | Biology | Why are orgams so short lasting? | likely so we copulate more frequently (maybe with more partners) to increase our reproductive success and bonding in pairs. also because if they took longer we'd probably never do shit else | 1 |
i4a0yg | Technology | Why adding @, & , *, #,%,etc makes your password stronger? | Because if someone has one arm they can’t press the shift button to do a special character therefore they can’t hack your account! | 17 |
o9leo2 | Engineering | If heat pumps are seen as a green way of heating a home, why are air conditioners seen as being environmentally unfriendly, when they're just a heat pump working in reverse? | Heating a home is seen as a requirement, whereas cooling a home is not necessarily the same level of requirement. The other reason is that when you have a heat pump set into a heating mode, the "waste heat" ends up in the house, so you are fully efficient. When you have it in reverse (like an A/C), the waste heat is exhausted outside. | 13 |
e1ji5p | Mathematics | I read that if there are 23 people in a room, the probability of any two of them having the same birthday is 50%. Can someone please tell me how ? | Let's use smaller numbers. Instead of birthday, let's look at weekday people were born at. With one person, chance of two people sharing weekday they were born is 0%. Say, this guy was born on Monday. If you add one person, chance they share birthday is 1/7. First guy was born on Monday, and second guy was born on one of the seven days of the week. Let's assume he was not born on the same day, and say he was born on Tuesday. Adding third person has no matching birthday if he wasn't born on Monday or Tuesday. 2/7 chance. For fourth person, it's 3/7. So if you look at these odds for 4 people not sharing weekday, the way it works is that with one guy there can't be match(100%), and when you add second person there can't be matching birthday(6/7 chance), and third guy can't match either(5/7 chance), and fourth guy can't match any previous three(4/7). "And" in probability means multiplication, so to get combined probability of that all, you multiply. 7/7 * 6/7 * 5/7 * 4/7 = 120/343 which is about 35%. Why it works is that you can't have *anyone* sharing birthday with *anyone else*. This restriction seems innocent at first, but as you add more and more people, you add more possible pairs of people whose birthday can match. Like, fourth guy had three possible days which would screw this up. In the original birthday problem, 20th guy had 19 dates which would end up in producing a match. | 4 |
ishw0h | Biology | How do sperm cells move their tails if they are too small to develop muscles? Yes, I did Google the answer but the explanations I found assumed quite a bit of knowledge on chemistry and would definitely not be suited for a five-year old! | Not the way you think according to this article. URL_0 | 1 |
8ecwvv | Biology | Do people of a darker skin complexion attract more sunlight and because of that are hotter outside in the sun? | Technically, yes. Melanin is the pigment that gives people a darker complexion, and therefore absorbs more heat. This might seem counterintuitive, but ultimately, the heat is not the damaging factor here, UV is. Melanin helps to dissipate UV radiation, thereby helping prevent skin cancers. Its production is stimulated by the UV radiation from the sun. So yeah, if you get darker you do get hotter, but you're protected better from the more dangerous UV radiation. | 1 |
5q975p | Repost | How did Hitler rise to power? | Like the populists do it today. He promised everybody what they wanted to hear while presenting "alternative facts". He found a scapegoat for the people to blame for their own faults: Foreigners, yews (Muslims weren't broadly known then). He promised jobs, he promised higher wages. He said "Germany first!". He used easy to understand paroles so that even the dumbest person could scream them. He blamed his predecessors for everything bad and even twisted the truth to depict good social changes from his predecessors as something bad. By the way...Any resemblance to a living politician is purely coincidental, likewise the resemblance to fish. | 3 |
g3mjhd | Biology | Why do hangovers last longer as we age? | Your liver, along with all your other organs, functions less optimally over time. The ability to remove toxic metabolites of alcohol slows down. It's also a fact, though still not fully understood, that older people have lower baseline hydration. Wrinkly dry skin is a sign of that (oversimplifying, many other reasons for skin aging). Less water retention = worse hangovers. Consider that even without being hungover, a mere few percent of dehydration will impair your nerves and muscles, slow down your reaction times, interfere with hand eye coordination and even make you perform less well on standardized tests. | 3 |
bl1n7p | Other | What happens after a coffin has decomposed and the soil on top eventually sinks? Are there people in charge of keeping an eye out for the ground sinking and they just fill it in when they notice? Wouldn't family members and the like be traumatised by finding the ground on the grave to be sunken, or by causing the grave to sink when walking over it? | The weight of the dirt actually crushes most coffins so the sinking will actually happen within 24 hours that's why they usually pile "extra" dirt on top. Effectively there is very little change after a few months. | 2 |
66tanr | Other | Why are tv shows set and filmed in different Locations? | Because then all shows would be set in California, NYC or Canada. For one, this is boring. Secondly, you can't have the same plot lines and feel in every place. Dexter would feel very different if set in LA. Other shows like The Wire or Friday Night Lights just wouldn't work outside of their locations. | 3 |
6a80k6 | Culture | Why do the Oscars tend to favour more critically successful 'artistic' movies, whilst the Grammy's favour more commercially successful 'mainstream' music? They are both the biggest award ceremonies of their respective mediums- if they were reversed then The Avengers would have cleaned out the oscars, and a relatively unknown band would have done the same at the Grammy's. Wondering why this is. | My take is that Oscars have a lot more prestige as an award whereas most musical artists have more prestige than the Grammies themselves. As such the Oscars will get ratings regardless of who wins, but the Grammies rely on the popularity of the awardees to get ratings. Like, an Oscar winning director has pretty much automatically 'made it' and is going to have a certain level of respect for the rest of their career. Christopher Cross won five grammies for his debut album, and is now so obscure his new albums don't even get their own wikipedia page. Can you imagine a director getting five oscars for their debut movie ever releasing anything that didn't have a wikipedia page? As a sidenote Cross also won one Oscar for writing the theme song to Arthur, and most people probably know the tune (or at the very least are aware of the movie). | 35 |
abp87l | Biology | We can freeze human sperm and eggs indefinitely, without "killing" them. Why can't we do the same for whole people, or even just organs? | Because sperm and eggs are just single cells. Organs and organisms are collections of cells that must operate in unison or the entire organism dies. If you have 5 million sperm cells and your freezing/thawing process kills half of them, you still have 2.5 million viable sperm cells to rely on, and only need one for success. If you freeze/thaw a person and kill half their cells, you end up with a mess. | 15 |