q_id stringlengths 6 6 | category stringclasses 12
values | question stringlengths 5 4.6k | reponses stringlengths 28 9.92k | response_number int64 1 489 |
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cfb6bj | Biology | Why does our blood pressure stay lower for a good while after a hot bath? I understand why hot water would reduce our blood pressure, but why wouldn't it immediately go back to normal once we get out of the bath? Especially if we rest sitting/lying down afterwards..! | Hot water causes vasodilatation which feed into two systems while in hot water - it helps to disappate heat but also, water warms up the blood in our body, raising core body temperature. After you get out of the hot water your body is not giving away all the heat you have accumulated at once, but body is disappating it... | 1 |
f2pa9n | Biology | SERIOUSLY, what are hiccups??? | It's just your diaphragm going into spasm. Normally the diaphragm works rhythmically unconsciously, but with conscious control you can stop it or use it to expel air so you can talk etc. When it goes into spasm it jerks suddenly causing that horrible sensation we call hiccups. All the old wives tales such as holding yo... | 3 |
n8o4p6 | Earth Science | Do female animals menstruate? | Yes. But it is much less involved. Human females spend a lot of resources to get ready for a short pregnancy, which requires developing the brain very fast. So they have much more blood by comparison. | 4 |
aj4a17 | Biology | If the Great Lakes were formed by melted glaciers from the Ice Age then how did they develop a fish population? | Birds. Sometimes when the wading birds are flying around, they will have mud on their webbed feet and there will be some fish eggs on it. My mother had a pond on her farm, isolated from everyone and everything except the wildlife. One day she showed me this odd long fish, like a gar, in it. Now, that pond had been drie... | 16 |
6stn42 | Culture | How Did Sikhs Come to Be, And What Do They Believe In? | Sikhism is based on the spiritual teachings of Guru Nanak, the first Guru, who started the religion around 1520. The first 10 Gurus wrote the Guru Granth Sahib, the religion sacred text. Three Pillars of Sikhism are: 1) Meditation on God and reciting and chanting of God’s Name—Waheguru. 2) Life as householders and hone... | 1 |
jwnayi | Biology | Why is one nostril blocked while the other is unblocked when breathing through your nose? | It's all about maintenance. Temperature regulation and immune response. Your lungs need to keep to a good temperature, and the nose can get quite cold. So to keep things regular, one side blocks up to gain temperature, and the other cools down. This is why it is worse in colder environments. | 7 |
boef62 | Other | In the movie Intersetllar they said how one hour on the water planet was a year on Earth, so how does that actually work? I have never been able to figure it out. | Time moves more slowly around immensely massive objects. If I remember correctly, the water planet was orbiting a huge star or something. | 3 |
bzin6b | Technology | What's the difference from installing and downloading? | You order delivery food. The guy delivers the food. That’s downloading. You “unpack” the food to eat. That’s installing. You eat the food. That’s using the program. | 3 |
6mggrz | Engineering | Why didn't old massive sailboats flip over, and why didn't their masts break being so far from CoM? I'm guessing they had massive heavy fins at their bottoms for the first question, but idk for the second one. | They did not have massive fins but they had lots of weights at the bottom of the hull to counteract the leaning caused by the wind pushing into the sails above. As for the mast breaking, wood is pretty strong and bends before it breaks, the sails further up on the mast were smaller to reduce the load and in strong wind... | 4 |
m6q7rw | Technology | Why do videos from 10+ years ago have such potato quality these days when they looked fine back then? Unless I'm misremembering, but I feel like I didn't struggle to make out details in some videos back then the way I do these days, because the quality seems so degraded. | It’s a combination of having your expectations elevated by modern resolutions and the fact that screen sizes are generally just much bigger now. You used to watch low resolution content on tiny screens and that was all you knew. Now you watch super high resolution content on very large, high resolution screens. The old... | 3 |
jmlp46 | Other | why does having a long story before a recipe help websites get better search engine results? | SEO. Search Engine Optimization. Google (or any search engine you're using) has a crawler that goes out and gathers information about all the content they can find on the Internet. The crawlers bring all those 1s and 0s back to the search engine to build an index. That index is then fed through an algorithm that tries ... | 11 |
76jxgh | Culture | I keep reading that Greeks didn’t have a word for blue and humans couldn’t see it until modern times. How is it possible that our ancestors didn’t see the color blue? What did the sky look like to them? The ocean? | Why do we have separate words for blue and indigo? They're essentially the same thing, only darker and lighter. What we refer to as 'blue' is a colour that was always there, there just culturally wasn't a seperate name for it. In the same way that we Brits talk about rain in terms of drizzle, sleet, spitting, raining c... | 5 |
6eeofa | Mathematics | Why every number n^0 is equal to 1? | One small catch: n^0 is *not (necessarily)* equal to 1 when n = 0. Usually when n=0 you will have to do some limit analysis to see if you can assign a value, depending on the actual function you are using. Otherwise it is simply undefined. | 5 |
crwdiu | Engineering | How do people build things like oilrigs and bridges over water? | Oil rigs are weighted floating pontoons (heavier on the bottom than on top to prevent capsizing) that are anchored to sea floor - the pontoons are built closer to shore then towed to postion before being anchored - then the rest of of the rig is built on top of the pontoon by cranes taking construction materials delive... | 2 |
frpe7r | Chemistry | Why does NaCl solution conduct electricity while solid NaCl doesn't? | When you dissolve an ionic substance (like NaCl) you actually no longer have NaCl what you have are Na+ and Cl- floating around in the water. Since these pieces carry a charge, they can arrange to conduct electricity. & #x200B; EDIT: Since people keep asking why salt water tastes salty: Your salty receptors detect the ... | 9 |
il4doq | Biology | how is the passage of time consistent between people/animals? The brain is made up of chemical reactions happening all the time but do we experience it the same? i.e. your 5 seconds is the same as my 5 seconds | The brains of all people work in a similar way so they perceive time at a mostly same scale. Even if some differences occur, nobody can notice them because the language we use synchronizes us: we tell a child "this timeframe is called five seconds" and the child remembers what a second means. Even if his perception of ... | 2 |
em8k0l | Biology | what actually is the noise our belly makes when we are hungry? | What about that sensation in the throat? Peristalsis? | 13 |
7vapgd | Physics | Why is centrifugal force an “imaginary force”? | Imaginary, or fictitious, forces are poorly named. The name doesn't really mean they don't exist. Rather, they are "non-inertial." I think this is a better name for them, because it gets away from the whole "You're imagining it" hullaballoo. They exist. They just exist in non-inertial frames of reference. They're cause... | 2 |
6hcxad | Chemistry | How come when you take a pain killer (Morphine, Percocet, Etc.) while in pain, you don't experience the same euphoria while taking the drug without pain? | When you take an analgesic (painkiller) while in pain, the pharmacological effect is that it blocks the pain receptors in your brain from receiving their signals. This may or may not correspond with the production of pleasure-causing chemicals such as dopamine, depending on the active ingredient(s) in question. This is... | 2 |
l7ckr5 | Economics | Stock Market Megathread There's a lot going on in the stock market this week and both ELI5 and Reddit in general are inundated with questions about it. This is an opportunity to ask for explanations for concepts related to the stock market. All other questions related to the stock market will be removed and users direc... | Did I miss the chance to make tons of money? And how/where exactly do the people who invested in game stop get more money? | 489 |
hbrdzc | Physics | How can the sun create so much energy if photons are massless? | A quick note, before I begin. The first law of thermodynamics/conservation of energy states that energy can neither be created nor destroyed, but merely transmuted from one form to another, like kinetic to potential, chemical potential to thermal, etc. At higher levels of physics you realise that *all* energy is really... | 2 |
auv5u8 | Biology | Why can't we drink salt water? | Salt was used in ancient times as a preservative, as it draws out moisture (water) from things. Normally when we drink water, our organs absorb that water and it is used in the cells of our body for various things. When we drink salt water, however, there then becomes a higher amount of salt than water in our body, so ... | 2 |
cnrin8 | Biology | What are genetic haplogroups and haplotypes and how do they work? | The human genome contains around 20,000 genes and plenty of other sections of DNA that are involved in controlling them. You may have learned before about Gregor Mendel's [law of independent assortment]( URL_1 ), which is the idea that different traits are inherited separately from one another. In reality though, this ... | 1 |
859lx5 | Technology | Why are satellites more powerful than wifi? To my admittedly little knowledge, our satellites are like 50+ years old in outer space but my wifi antenna is brand new and in my house. I can't get my wifi in my drive way YET I can get satellite signal for my GPS anywhere in the United States like immediately. Why? | GPS satellites broadcast a much stronger signal than your home wifi can. They broadcast on reserved frequencies that nobody else uses while wifi needs to be shared with everyone and everything. They also don't need to receive any data from your phone. It's a one-way system. | 3 |
9v5s37 | Other | What is the Silurian Hypothesis? My professor talked about it today in class and it just made me more confused. | Basically, it is the idea that an advanced civilization might have existed on earth at some point in its past and then was annihilated and went extinct, and since fossilization is rare enough for it to be possible that none of that species would happen to be found fossilized and any other remnants of civilization could... | 1 |
g2uypd | Technology | Why does movie volume vary so drastically from scene to scene? | It's a thing that became more prevalent in the last 10 years or so. If I recall correctly, sound grading in movies usually just sucks these days. I don't remember if I made this up in a dream, or saw a video about it a few years back... Something about not remastering for broadcast vs in theater, or something? Might no... | 1 |
5p3rhj | Other | Some entries on Wikipedia have bizarre spellings that appear to be how to pronounce the word, but are confusing. What do the weird letters mean? For example, this is apparently how 'Ireland' is pronounced: aɪərlənd | > this is apparently how 'Ireland' is pronounced: aɪərlənd In fact /ˈaɪərlənd/. This is the International Phonetic Alphabet, used by linguists (and in at least some countries most people with an academic education, especially those who have learned foreign languages) to exactly describe the pronunciation of the word. T... | 2 |
dc0jva | Technology | How exactly do magnetic waves become encoded/decoded (ie. on tapes) I'm fascinated by this article URL_0 Disney used magnetic tape to play commands for animatronics while rocket scientists used magnetic tape to guide nuclear missiles. All the explanations have said that a tape head is able to "read" these magnetic wave... | A tape head is a type of transducer. It can convert electric signals to magnetic fluctuations, and vice versa. Basically you have a coil of wire with a gap in it, and the gap is filled with a diamagnetic material, like gold. If you apply a variable magnetic field at the gap, it'll induce an electric current in the coil... | 2 |
iveilw | Other | Why do some stars, planets, and galaxies have really cool and unique names while others are just numbers? | Because the cooler named ones were discovered first. At some point there were just too many so they started giving them only scientific names. | 1 |
auqkg9 | Biology | How does a body generate heat from the food we eat? I get that our organs break it down into smaller and smaller bits, and the bits mix with oxygen or something, but I clearly need it ELI5. | Any energy transfer will result in the loss of energy as heat (think about how friction makes things hot). Your body uses various different molecules from the food you eat and strips the electrons from the them, passing them off to a series of carriers. Eventually, the electrons are pushed through a special cellular ma... | 2 |
avizdj | Physics | How can you stick your entire hand into an open flame[camp fire, lighter] for a few seconds with minimal damage, but touching a hot metal [stove] burns instantly? | Uhh, wait, if you stick your hand in a fire for a few seconds, you will get burned. & #x200B; You can move it in and out very quickly(less than a second or so), but a few seconds will earn you a third degree burn. | 4 |
7gih9w | Biology | why canned food last much longer than other packed food? Why does storing food by canning it make it last so much longer than any other method? | So there is bacteria everywhere right? This bacteria causes food to spoil. Once you put food in a can and create a hermetic seal (fancy term for saying nothing gets in or out, not even air), you have to cook the can. It is cooked in a giant pressure cooker with steam until all of the dangerous bacteria is killed off. T... | 14 |
nc2u0z | Other | Why do we get angry and frustrated when we’re in pain? Is this some sort of thing the brain does to help cope with pain? | Psychologist here! We do something called emotional regulation, which is a cognitive process. Our brains can only process a certain amount of input every second, so it needs to filter out a lot of the things our senses perceive at any given moment. Pain is high priority, so it is hard to filter out. Compare it to a per... | 1 |
6vgn3u | Biology | How did the world develop STIs if you can only get it via sexual contact with the infected? Basically how did the patient 0 for gonorrhea and herpes contract them. HIV was apparently because of some guy and a monkey? | HIV was not because of sex with some guy and a monkey. That is a myth. Most sexual STIs started off as different kinds of infections that found living in/on the genitals to be more advantageous, and once there were transmitted via sex. Over time they mutated to primarily be transmitted by sex. | 1 |
iyne3w | Other | How Would A Non-Peaceful Transfer Of Presidential Power Work? | That's sort of like asking how trash pickup will work on Mars. The US has never experienced one and we don't have any data points on what would happen. That being said - The Constitution/Law do spell out some clear points. 1) The President's terms ends on Jan 20. There are NO exceptions to this. So on January 20th if a... | 1 |
60m47b | Technology | Why are my old smartphones (2013) so slow today doing simple stuff like photos and internet browsing when it could run Playstation 3 graphics games with ease? | Planned Obsolescence. URL_0 Basically, if you make the perfect product, then people would not need to replace or buy a new version. However, if you ensure that your product degrades over time, then you'll force your customers to make repeat purchases. | 1 |
bi3fm0 | Physics | Why does the moon look huge in the distance when poping over a mountain but small on a picture or a video? | Forced perspective. When it's next to the mountain, your mind has a frame of reference. In a picture, or even just higher in the sky, you don't have that same reference. | 10 |
a4m87s | Other | the difference between a legal and an illegal war. Yes, I know there are numerous treaties and conventions governing conduct in war but is war itself legal and is there a distinction between a legal and illegal war? | War is illegal, with 3 exceptions, as stated in the Chapter VII of the UN Charter. You can declare war if you are going to get attacked imminently, war can be allowed by the UN Security Council, and you can engage your troops in a country that requested assistance and has accepted your intervention. | 6 |
ai4fw4 | Physics | Why are we able to see more with a telescope if we're not shortening the distance between us and the "target"? It's stupid, I know, but holy cow I can't understand how we can se more with a telescope. It seems that we're closer to the object without moving closer. Amazing, really. It seems that we're shortening the dis... | For the same reason you can see things larger with a magnifying glass. Think of a telescope as a series of small magnifying glasses arranged in such a way that the small speck of light in the night sky appears larger and more detailed. Its all due to the type of lenses used. | 5 |
76zsns | Physics | What is local realism? (Quantum Physics) I watched an interesting [MinutePhysics video]( URL_0 ) on Bell's Theorem and how local realism may not exist. I'm not a mathematician, so some of it went over my head. But as far as I can tell, they never explain what local realism is. So what is it and what implications would ... | Here's the version I give high school students who have no idea about literally anything: In quantum physics we can prove experimentally that particles vast distances apart seem to communicate with each other instantaneously. This seems to violate at least one conventional metaphysical "truth" about the universe. The s... | 2 |
adqfyk | Biology | Why do our eyes change focus when looking at a screen vs reflections on that screen, even though it's the same surface? | Go to a bathroom mirror and stick a small dot of stickynote or damp paper or tissue on its surface to make a "model" of a reflecting screen. Then back away from that mirror a bit, say, three feet, and line that dot up with your nose. Focus on the dot for a second. Then focus on the reflection of your mouth instead, and... | 1 |
crue9h | Technology | How can nuclear launches be detected and identified? If Russia launches at The US, how does the US know that it was Russia? | There's a few arrays of satellites in orbit watching for bright or hot spots on the ground. A rocket launch is this intensely bright and hot spot for about a minute, far far brighter than anything around which makes it easy to spot. All rocket launches and missile tests are publicized in advance because they'll trip th... | 3 |
76xnq6 | Engineering | - Are speed bumps designed to damage your car if you go over them too fast? | Some are, yes. We have the normal speed bumps but there is a whole road nearby that uses ~~his~~ these rubber things bolted down and even if you are going really slowly the jolt they give you is enormous. | 7 |
n1d6tu | Technology | How does ray tracing work? | Former game developer here, So you have 3D points, 3 points make a triangle (polygon) in 3D space - the smallest primitive object you can make. Everything can break down into terms of triangles. The surface of that triangle also so happens to describe a 2D plane that goes on to infinity in that 3D space. The surface of... | 3 |
jwperd | Biology | Why do we have different handwriting even though we all learn to write the same letters(in our respective languages, of course)? | Probably because people are just overall different. People have shaky hands, steady hands, or don’t practice overall. Same applies for art, I’m horrid at it while my other friends are so much better at it than I am | 2 |
7ohthi | Biology | Why do men and women orgasm so differently? | Because each sex has a different goal during the act of reproduction. A man's role is to achieve climax and deposit the sperm before other males can potentially interfere, while the female's is to achieve a convulsion of the vaginal walls to facilitate the sperm's movement towards the potential egg and future offspring... | 2 |
hs17al | Biology | why is it when you take a portrait photograph of somebody it looks way worse when you mirror it; and does that mean we look better in the mirror or worse? | Oddly, the image you think of yourself isn’t the image people see when they look at you. We see our reflection more often than our front-facing view (unless you’re a movie star?) and that is partially why some people claim they aren’t “photogenic”. They truly believe they don’t look “as good” as themselves in pictures ... | 2 |
b5w6wd | Physics | When on a trampoline, why does someone bouncing near you send you much higher, and also how does 'stealing' someone's bounce work? | When they get close to you, the trampoline is stretched even tighter than it usually is, allowing you to bounce higher when it’s being stretched by your friend. When your jump is stolen, their weight pulls the trampoline away from you, and so the trampoline has less tension underneath you, and thus can’t launch you bac... | 1 |
6kpgdc | Biology | How do we know what colours dinosaurs were? | We don't, for the most part. [Whilst some fragments of colour have been preserved in dinosaur feathers]( URL_0 ) (and this is cool as shit!), this is a recent discovery. So most of the artwork you see depicting dinosaur colour is guesswork. But it's educated guesswork. It's based on what we know about the animal and co... | 2 |
iq101w | Mathematics | How do doctors make predictions of how long someone will live or if they'll ever walk normally again? I was rewatching an old video on YouTube and the guy was able to walk again after 10 months of practicing yoga and losing 140 lbs. If no one on earth can exactly predict when someone will die or if they'll be able to w... | I'm an MD. The question is so broad because it's a very different question/anwser in different clinical settings (geriatric patient dying in the ICU from sepsis vs pediatric cancer diagnosis) , and crosses different diagnoses and pathology. Usually these types of assessments are multi-factorial but a few points: 1. "Do... | 18 |
itu7j9 | Technology | How does Disney+ prevent screen shots?I'm having a hard time imaging that a website can do that.Like cant you just snip it or us another program? | They use something called Google Widevine, and basically the way that works is the encrypted video stream is passed directly to the hardware, the OS draws the window as having a black box where the video player should be, and the processor at the hardware level decrypts and draws the media over that black box. So to th... | 3 |
gouql9 | Other | why are guitar tabs upside down? I just started learning and it having the tabs this way looks very counterintuitive looking at it from a beginner's perspective. So why are they this way i would really love to know. | If you look down at your guitar you will see something similar to the tabs on your screen. The tabs are not really upside down. | 2 |
elbyu3 | Biology | Why being in any pose in bed in the morning is so comfortable yet it takes time to find comfortable pose trying to sleep? | When you go to sleep it takes time to process how reality rawdogged you with bullshit all day, then the mental gymnastics of convincing yourself things will be better soon, finally relax. Takes awhile. When you wake up from the dreams you had from buying into your own horseshit, you are in a fog for a bit. everything s... | 9 |
64qckh | Culture | Why do people from the US never identify with English culture? I often read about Italian-American, Irish-American, Chinese-American, you name it, but not a single time have I read someone proud of her/his English origins. | When I asked my parents why we don't celebrate anything to do with our heritage, my mom replied "we moved here for a reason" Idk if it adds to the topic, but might have something to do with it. | 34 |
i10qww | Physics | how come the splitting of atoms makes an explosion? | From what I recall from my nuclear chemistry class, its about the energy economy of the universe. Elements, compounds and molecules need energy to be put in to form. That's why naturally occurring elements are formed in the cores of stars or during supernovae. When you split an atom or start a chemical reaction, you ar... | 2 |
dmas7e | Biology | How does my body know to blink and stop something from hitting my eye that I couldn’t even see? I was cooking earlier this evening when the grease popped in my pan causing me to blink. This stopped a piece of grease from hitting my eye, and instead burning my lower eyelid. There is know way I could have seen that proje... | The corneal reflex (blink reflex) can be triggered when sounds greater than 40-60 db are made. I'm guessing the sound of the oil popping is why you blinked. | 3 |
ajcs7e | Physics | Why is the temperature usually less cold when it's snowing? | If it's snowing that means there is cloud cover. Cloud cover acts as a blanket over the land and holds in heat. When there are no clouds the heat from the ground can radiate directly out into space. That's why it tends to be colder with no clouds. | 5 |
bj99ba | Other | Why is lumber sold based the size it was before it went into the planer? | In the UK it is based on whether the timber is planed or not. Unplaned timber is called the nominal size, so 50mm x 100mm (which is near enough 2 x 4) actually is 50 x 100. Unplaned timber has a rough finish and is generally used a lot outside or where it can't be seen. Planed timber, (finished) is now mostly sold as 5... | 6 |
86u0qv | Biology | if fruit is sweet to encourage animals to eat it and carry the seeds away from the parent tree, how do lemons and limes fit into this mix? | Some animals like lemons and limes the way that some people like mint or cinnamon. With taste is all about how you choose to feel about these things. You also need to understand that animals are different, they have different taste receptors. Cats don't like sweet things at all, but there could be animals that love bit... | 13 |
9j2bh5 | Mathematics | How do calculators find square roots? Is it just brute forcing? Like computing for some 'a' (number for which square root is to be found) divided by some number 'i' until it equals i? Like so: ***a/i = i , computing through all values of i. Like 256/i = i is satisfied by 16.*** Is there some other method they use? Than... | Pocket calculators often use the [Babylonian method]( URL_1 ). *Edit: This is the same as Newton's method/the Newton–Raphson method [as shown by /u/X7123M3-256 here]( URL_0 ).* --- ELI15: **You have a number `n` and you want to find its square root `√n`. You also have a guess of the square root `x`** (many calculators ... | 4 |
6levy8 | Culture | How did 4chan become so heavily affiliated with/occupied by members of the alt-right? | 4Chan provides absolute anonymity, and therefore no accountability for what you say. This means you can say literally anything, and not only will it disappear in a few days (or a few hours on fast-paced boards) but you can never be tied back to something horrible you've said. This means the the entire culture is based ... | 14 |
d7b7yi | Other | How does one distinguish between good acting and bad acting? | Do you see a person playing a role or just the character itself? A good actor is invisible within the character they perform. | 2 |
lx94lc | Biology | Why do we sometimes wake up, say a bunch of random/nonsense stuff, and don’t remember it? | When you sleep, you enter a phase called REM, or 'Rapid Eye Movement'. It's that point in your sleep where your body essentially reorganizes the messy clutter in your brain to, amongst other things, store memories. This is the deepest point of your rest, so you need time to rise to a light sleep before you wake up in t... | 1 |
k2arl1 | Earth Science | Why does smoke from a cigarette or steam from a pot tend to lose shape nearly instantly, yet clouds seem to maintain their shape for a longer period of time? | Ever flown through a cloud on an airplane? You're not headed towards some big wall of cloud - you go through wisps of fog that get thicker and thicker. But there's a whole lot of it. So if you see it from a half mile away, you don't see that wispy edge, because it's too far away. You just see the thicker-and-thicker pa... | 4 |
5vzhgz | Technology | how do traffic lights know when to change? | It depends on the lights. There are a wide variety of control mechanisms for traffic lights, so I'll try to break them down and list their pros and cons, and where they're more commonly used. I should clarify that my experience of traffic systems is UK based, and while much of this is international, regional difference... | 1 |
5tv3w5 | Economics | Why do we still have to file taxes? | What you are describing can definitely be achieved using pre-filled forms. Ideally, the IRS would send you a tax return with all numbers available to the IRS filled in the correct spots. You would then review and make sure it is correct. You could even bring it to a tax professional to look it over for you. What's stop... | 37 |
am9pwe | Culture | Why do Australians and Brits consider it proper grammar to say “go to hospital” and leave out the “the”? As an American I would say “go to THE hospital” but I would happily say “go to school” (no “the”) | You would say "go to the school" when thew school is just a place you were visiting. "Go to school" implies going there as a student. "Go to the hospital" is something we say when we are rendezvousing at the hospital for whatever reason. "Go to hospital" means we're going to one as some kind of patient. | 5 |
8sfq89 | Culture | Why didn’t white Americans enslave Native Americans systematically on a wide scale rather than shipping slaves all the way from Africa? | One of the main reasons was the fact that Native Americans were not able to keep up with the rigors of labor. Also some Native Americans were not able to withstand some of the diseases that the Europeans brought over . The Africans could with stand those diseases for the most part could work for a reasonable amount of ... | 7 |
awpmxa | Chemistry | How do some foods "melt in your mouth"? | Well "melting" via the heat of the food or your mouth causes some of the solid matter like lipids and proteins to desynthesize. But your saliva also breaks down carbs in your mouth through enzyme activity, making them more liquid like and therefore easier to absorb. | 1 |
deux2r | Technology | Why do downloads take so much time? Why do downloads take longer than like 2 seconds? Couldn't it all just get sucked up like a caprisun? What is the reason for the device to slow the intake of data? Like I'm downloading a game on my PS4 and it's going to take 5 hours, why is that? Thanks in advance! | Because internet bandwidth works like water pipes, the flowing water is the data. The size of the pipes represent your internet speed and the pressure of the water flow represent how fast the download server is hosting your download. The files come in specific sizes and you need to download each portiom of the data gra... | 1 |
6s92hm | Repost | Why do toilets(in america) use clean potable water? | I mean I would guess one of the reasons is so that our pets and children wouldn't get poisoned from drinking toilet water. | 58 |
91idqg | Technology | Why don’t viruses in virtual machines effect the host computer? | A virtual machine is just that— virtual. Your computer is basically figuring out “if I was a computer following this code/instructions, what would I do?” rather than doing those things in a way that affects its own system and files. So if the code says “take tax/financial documents stored on your desktop and send it to... | 4 |
6xpk1r | Technology | With blockchains whats the difference between proof of stake vs. proof of work protocols? | In proof of work, computing power is used to validate blocks of transactions. This system uses the high cost of the limited supply of computation power in the world as its incentivise for miners to play nice. Attacking the network would cost a lot because of the high cost of hardware, energy, and potential mining profi... | 1 |
aeeen7 | Technology | Fiber Optic Cables | In very very very very layman's terms, based on my understanding, light goes Bing boing boing boing bong all the way through out the other end. | 6 |
kxqw7k | Biology | Why do we sneeze if we look at the sun for a second or rub a feather on our nose? | The photic sneeze reflex (also known as Autosomal Dominant Compelling Helio-Ophthalmic Outburst (ACHOO) syndrome[1] or photosneezia, from the Greek φῶς, phōs, "light" and colloquially sun sneezing) is a reflex condition that causes sneezing in response to numerous stimuli, such as looking at bright lights or periocular... | 1 |
a8gv3g | Other | why does chocolate milk from the store taste so much better than chocolate milk you make at home? | It’s all about the mouthfeel, store bought will have a thickening agent added to it at the factory. I doubt you’ve ever done anything at home to thicken your own chocolate milk. Mouthfeel refers to the physical sensations in the mouth caused by food or drink, as distinct from taste. But despite the fact that it’s a dif... | 3 |
bx4ckw | Biology | Why do powerlifters wear a strap around their stomach? How does that help them lift more weight? | Simple analogy. Stand on an empty coke can and it crumples Stand on a full pressurised coke can and it has strength A lifting belt turns your body into the full coke can - it makes it more rigid by increasing internal pressure | 6 |
a1ht67 | Engineering | How do nuclear fusion reactors generate electricity In a nuclear fission reactor I know they heat water into steam which turns a turbine but how are they planning on making a fusion reactor work? | There are no commercial scale fusion processes that have yielded useful energy yet. In theory, once they are perfected they'd operate like a regular Fisson/Coal/Gas plant and use the heat to power a steam turbine. While there are other more sophisticated ways to get electricity from fusion, the tried-and-true steam tur... | 2 |
a5c9de | Biology | Why the Top of my Mouth Becomes Slightly Sore After Eating Some Foods Title. After eating some foods - especially ones that require more chewing, as one might expect, the top of my mouth becomes (slightly) painful to the touch, and the feeling fades until it goes away after a few minutes. | Some things have a rougher texture than you might realize. I notice this effect after eating tough breads or crackers. I think this might cause extremely small abrasions on the roof of the mouth, that eventually get progressively worse until you stop eating the food equivalent of brillo pads | 2 |
7v0idv | Culture | Why did the sun appear on the North side (on their right as they traveled West) of sailors doing around Africa in Herodotus' Histories? | I'm not familiar with the story you're talking about. But in the Northern Hemisphere the sun sweeps across the southern part of the sky, and in the Southern Hemisphere it sweeps across the northern part of the sky. Half of Africa is in the Southern Hemisphere, so as you sail around it you're going to see the sun in the... | 3 |
bp5mwq | Biology | How is mustard zero calories? Or is this just like a “round down”-ish type scenario? | Well thanks everyone! I expected this to be more chemically complex, but now I feel bad about not googling it. I truly feel 5. Well done all around. | 4 |
d4jjsu | Biology | why does our voice change when we hold our nose? | The human skull has a fair amount of void space, most of which is near and around the nose. This allows sound to resonate and if you hold your nose when you talk that effect is lessened. | 1 |
6v6a7v | Culture | In ancient times when armies of 20,000+ would march/sail into battle how could they possibly afford to feed that many men for that long. | Another aspect not mentioned yet was rationing. It was in everyone's self interest to make sure they weren't gorging on food or supplies that might save their life if they made it last. | 9 |
e7r3x3 | Other | Where do black market organs end up going and why? I've heard about how much human body parts are worth on the black market, but I'm curious as to why and where they end up going? Surely anyone able to afford a black market liver for a liver transplant can just go to a hospital and find one somehow right? Are hospitals... | The "problem" that black market organs solve is not the lack of access to a healthcare system for wealthy individuals, it's a lack of organs available through ethical means. Someone can wait for a very long time on a donor, or they might not be prioritized depending on what system is used to determine who is eligible t... | 2 |
93zdwi | Biology | [deleted by user] | Pressure differentials. Basically, water is more dense than air, so going under it means there is more pressure trying to push into the holes in your body. Water is trying to go into your ears and nose, but there is already air in there, so the air gets trapped. As the water tries to fill these spaces, it's going to eq... | 3 |
gs2tt5 | Biology | Why pure oxygen is poisonus? | If there is too much oxygen in the air you breathe, all of your red blood cells will be carrying as much oxygen as they can, but the remaining oxygen that hasn’t been absorbed will coat the surface of your lungs. This will cause a number of things to happen: fluid will build up in your lungs, you will have to breathe m... | 1 |
fvo8rf | Physics | Why is it that when both a man and woman sing the same exact note in the same octave, the man's voice still sounds lower than the woman's? Is it an auditory illusion (we only perceive it to sound lower), or something with the vocal chord structure? | Because voices are not a single frequency. They have harmonics and atonal variations. That's what gives people their distinct "voice." And why some voices sound "better" than others, even if they are both on key. When singing a note, the loudest frequency would be the frequency designated by the note being sung, but th... | 3 |
8chdih | Technology | How did people get domain names before domain name registries were available? I don't know if I'm asking this right,,, | They didn't. There has always been domain name registration. If you mean the companies like GoDaddy etc, they're just registering you with the actual registrar (Network Solutions) for you, for a fee. | 2 |
nkqu4y | Biology | How did primitive humans, with a top speed of 28 mph, hunt large mammals like deer, bears, wolves, etc, that can reach speeds of near 35 - 40 mph? | Most animals can outrun humans, but only for short distances. Humans run slower, much slower, but we can go forever. There is no marathon running in the animal Kingdom, but if there was humanity would be champ. Ancient humans would track animals through the bush, the animal would run away, and the primitive humans woul... | 10 |
kldvda | Biology | Why dosen't Melatonin cause tolerance like other drugs that act in the brain? | You might be confusing tolerance with dependence/addiction. For something to be addictive, it has to create a reward in your brain, usually by causing an increase in dopamine. Melatonin has no affect of dopamine or rewards, so addiction/dependence doesn't develop | 2 |
83vmuj | Biology | Why are most of the herbivores mammals like elephants, rhinos, hippos, giraffe, etc. so big in size? Even in the jurassic era the largest dinosaur was a herbivore. | Metabolism is more efficient in primary consumers, the top of the trophies food chain gets less energy. Also, higher levels of oxygen in the Carboniferous period led to highly efficient aerobic respiration resulting in larger animals. Those animals you mentioned have evolved slower to fit with the lower oxygen levels. ... | 11 |
8etlq3 | Other | In regards to colleges/universities, how does "tenure" protect someone from being fired? In TV/Movies, you often will see people mention that they have "tenure" which somehow protects them. In the US at least, 49/50 states have "at will" employment which essentially means you can be fired for any non-discriminatory rea... | I'm far from an expert, but I believe it's essentially an employment term that acknowledges an advanced academic skill set and offers permanent employment to retain access to those skills even if they're not currently required or aren't meeting any desired output criteria. I think it effectively protects you against be... | 2 |
gbc8ea | Biology | Why do dead bugs and mice 'stiffen up' in specific positions where as other dead animals simply go limp? | I don't know about bugs, but animals don't go limp, I mean immediately after death they do, but within hours rigor mortis sets in. That's because the SERCA pump required to sequester calcium in storage (terminal cisternae, sarcoplasmic reticulum) needs energy (ATP) to operate. No oxygen and metabolism upon death means ... | 3 |
cyrutj | Psychology | What is the memory palace technique and how can it be of benefit in certain situations? | The memory palace does not need to be based off a real city. In fact I bet that would be way too complicated and wouldn't even be helpful unless you're a complete expert in this technique. The technique is to "place" information in a mental map of a physical location, usually like a house (or a palace for the pretentio... | 1 |
712012 | Technology | Trains seem like no-brainers for total automation, so why is all the focus on Cars and trucks instead when they seem so much more complicated, and what's preventing the train from being 100% automated? | Trains are already largely automated, at least on the road. Two people run most trains in the USA, the Engineer and his Conductor. Together, the monitor/control anywhere from a few cars to several hundred. There are several issues with totally automating trains. Computers are fairly good at handling expected situations... | 40 |
a9sdfy | Physics | the difference between a ground and neutral line in electricity. | Ground is earth ground. Neutral is a current carrying wire just like a hot wire. In an electrical system the neutral wire acts as a return pathway for AC power. The neutrals are all tied back to a "neutral bar" and the neutral bar is tied back to earth ground. | 2 |
86qdtj | Physics | How do we measure and calibrate time? A second isn't necessarily a second. If I set the time on the microwave and oven at the same time, in a month one will change over to the next minute before the other. Is it just a guess when programming? How can we be certain we have an accurate measurement when needing an extreme... | A second is defined internationally as the time that elapses during 9,192,631,770 cycles of the radiation produced by the transition between two levels of the cesium 133 atom. That's the most precise, scientific definition of a second. There are a number of atomic clocks around the world that are all synchronized to ke... | 1 |
8ziyh3 | Biology | How does the brain/body measure dehydration? And is it possible for it to make mistakes? | Being thirsty is our best indicator that we're starting to become dehydrated. When you start to feel lightheaded after feeling thirsty, you've become more dehydrated. You should drink water or eat something with a decent water content if no water is available during those stages, as that's when it's easily fixable, and... | 2 |
cxu1va | Other | What’s Fermi’s paradox? | That given how long it takes to colonize the Galaxy, aliens shouldn't just be here they should be everywhere, but we don't see them anywhere. So is the Galaxy not colonizable or do aliens not exist? And why don't they exist when we do? | 6 |
8e49th | Biology | How do electron microscopes work? | I'll briefly say why we need one before attempting to answer your question. Why an electron microscope is needed? We see objects because light reflected from that object enters our eyes. There is a limit to how small an object can be to reflect light. If an object cannot reflect light, it can not be seen. This is why w... | 1 |
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