q_id
stringlengths 6
6
| category
stringclasses 12
values | question
stringlengths 5
4.6k
| reponses
stringlengths 28
9.92k
| response_number
int64 1
489
|
|---|---|---|---|---|
7mt07q | Other | After showers, whenever I rub my skin I get rolls of dirt/dead skin cells. Why is this? | (disclaimer: I'm no scientist.) Your skin regenerates/replaces itself every 27 days, that means, shedding off old skin cells, and replacing them with new ones. Your entire body does that, just not as fast as your skin does, as its constantly in touch with the outside world. If you dislike your dead skin cells, consider buying something to scrub your body while showering. | 2 |
hen8ea | Biology | how do we know there wasn’t a human race as established as we are now before? i understand that there would be remains, and some sort of proof, but how do we really know? like pre any sort of disasters (ice age etc) which wiped out everything? | We left some very unmistakable traces of our existence on our planet, everyone who could have come before us and achieved similar things to what we did would have left the same sort of traces. We know that nobody before us build an nuclear power plants or nuclear bombs because those leave quite some evidence behind. We know nobody before us went and extracted coal and oil from the earth in a big way like we did, because all the easy to reach stuff was still there when we started to use it. We know nobody before us domesticated plant and animals the way we did, because our ancestors had to start the process from start. We know there were no people in the past that crossed the ocean like we did because we see no evidence of any invasive species they would have brought along We know nobody before us caused the same sort of mass extinction that we did because we looked at the fossil record and what we are currently doing would stand out like a big asteroid strike. Any sort of civilization that went beyond the most primitive hunter gatherers would have made such a big impact on the world as to be unmistakable. Even then stone tools and bones could give them away. The idea frequently seen in older science fiction stories and some occult and conspiracy believers that there might have been civilizations before our own that fell before the current one rose up again or even the idea that civilizations cyclical rise ignores the facts. We have changed the face of the planet, if human civilization fell back into barbarism tomorrow the descendants who would rise up again would need to take a very different path than we did. A cyclical rise and fall is not possible. | 2 |
7fhnlt | Other | How does our brain create a mind? | Your brain is like a big jar of jelly with a lightening storm inside it. These little wire-like things live in the jelly and kinda keep the lightening going in the same general shapes. The bit that's *you* isn't the jelly, isn't the wires, it's the storm and how it rumbles around inside. Now, who wants a PBJ? | 6 |
5oebrg | Technology | How do computers go from physical parts to computing languages? Confusing title, I know, but what I'm asking is what is the link between the physical aspects of computers, such as soldering a circuit board to typing in programs like java? What are the levels in between physical components and digital programming? | [Here]( URL_0 ) is my answer to a similar question, if it helps you. | 2 |
774lu6 | Chemistry | Why is titanium flammable? Specifically titanium shavings | This is not really something special about titanium. Many materials have pretty much the same thing going on. Metals like titanium can oxidize. When that happens to iron we call it rust. With most metal objects they automatically form a thin layer of oxidized material on the surface. If you scratch that layer you expose the unoxidized metal which on contact with oxygen oxidizes. The problem comes when the protective layer can not form quickly enough. If you create lots of metal shavings you end up with a really big amount of surface area per mass of metal and all that surface area is exposed to oxygen in the air. A single spark under this circumstances can set it all aflame and lead to a small (or not so small) explosion. This can also happen with materials that aren't metal but are at least somewhat flammable. Wood dust can explode too. A famous example of stuff becoming explosive when turned into powder/shavings/mist are grain silos which can explode in much the same way. | 3 |
8o9zzm | Chemistry | Why does adding one methyl group to Adderall change it from being a common prescription medication to an extremely hard drug? | Adderall is not just a single amphetamine, it’s a carefully measured cocktail of about three salts and one binder. The difference from what I can find is that straight amphetamine is less potent due to a lack of a methyl base, and as such is released into the brain on more of a drip-feed rather than a rush. This gives more time for the kidneys to filter out the remainder and place it into urine. On the other hand, the addition of the methyl base to amphetamine increases its potency when smoked, so you get a more potent compound flooding the brain all at once. This flood vs measured release is what makes it addictive, your body can’t take having so much dopamine, serotonin and norepinephrine all at once, so it needs them at such high levels to feel normal. However, Adderall is not without risks and still has an addictive factor to itself. | 7 |
fjv5we | Biology | why do antiviral drugs not work in the same broad capacity as antibiotic drugs? Antibiotic drugs treat a large degree of bacterial infections, but viral infections seem to be trickier to develop medicinal treatment for. Why? | Bacteria are vulnerable in three different ways and each of the three groups of antibiotics targets one of those vulnerable spots penicillins, macrolides and fluoroquinolones URL_0 since viruses are not actually cells they don't have these key weak spots to target so the antiviral drugs have to be more targeted at the specific virus in order to somehow disable it. | 2 |
821ro5 | Biology | What exactly happens when humans eat a tide pod? | Probably most people don't actually *eat* such detergent pods, they merely bite into them and then attempt to spit the contents out. [Here is a good video]( URL_0 ) about what can happen when this is done, which basically comes down to them being strong bases (please excuse the pun). They are extremely corrosive to mucosal tissue and cause tissue death. | 1 |
f7wkrt | Biology | When putting your fingers over a bright light, why is it all diffuse light and we are unable to discern the bones? | You're not really seeing light passing through your finger - so there is no light passing across the bone causing the dark/shadow area you're imagining you'd see. You're seeing light refracting around the outer layers of your skin and causing it to illuminate, but not light passing through the center of your finger's flesh. | 1 |
7zynj3 | Biology | How does sleep debt/build up work? If I were to sleep for 24 hours could I then skip the next 3 days of sleep? If so how does it work and if not why does it not work like that? | This will likely get buried, but how would polyphasic sleep cycles play into this? It seems that your brain is going into maintenance during sleep, so how does shorter cycles get around that? | 26 |
6c1v04 | Physics | If you hovered over the ground in a helicopter for 24 hours, would the whole earth spin beneath you and return to the same spot? | The Earth, and the atmosphere around it, are spinning together. Everything on the planet is moving at the velocity of the Earth's rotation. When a helicopter hovers, it is carried along by it's momentum and the surrounding air mass just like birds, bugs, or any other in flight entity. So, you would not experience any sort of lateral travel while hovering. | 1 |
5yqzti | Biology | Where do habits like biting our nails come from? | According to [this NPR link]( URL_0 ) humans bite their nails because of something called pathalogial grooming. Pathological grooming is a type of grooming that goes "haywire" and the nail biting becomes triggered by stress, reading or any other regular every day action. At some point, further down the timeline, the actions don't trigger the nail biting anymore and it just becomes an automatic behavior. It's noted that pathalogial grooming is somehow connected to OCD. The one difference is that people with OCD hate that they have to wash their hands 5 times to feel clean or touch the doorknob 3 times before entering their house. Whereas pathalogial groomers usually get a satisfaction out of getting the right nail when biting them. | 1 |
j50226 | Biology | Why are there remains of food in our excrement? | It depends on what you ate and how you ate it. You see a big part of digestion is tied to chewing, it breaks down the food before it gets sent to the stomach to be broken down more. Sometimes foods that are tough to break don't digest properly like the hard shell of corn or food with high fiber. Surviving remnants of food in your feces ate the result of the body not properly breaking it down through the entire trip. | 2 |
lckr2l | Chemistry | Tumor infiltrating lymphocytes | If you've read journals you probably know enough to have a basic idea, but it's hard to say what that particular company is doing without knowing who they are. However, lymphocytes are the cells of the immune system that are able to recognize and kill cells that are not "self" (the body's own cells), or that are infected. Cancer cells are slightly different than the body's normal cells, so the lymphocytes can often find them and kill them. But tumors evolve the ability to evade detection by the lymphocytes. It also might become hard for the liver cells to get into the tumor to get at all of the cancer cells. So companies are trying to make lymphocytes better at getting into the tumors and killing cancer cells. This might be through creating vaccines against the cancer cells, or things like genetic engineering of the lymphocytes | 1 |
8aqxv4 | Physics | How does visible light fall within the electromagnetic spectrum? What do magnets have to do with light? Update: Found [this video]( URL_1 ), but this stuff is pretty complex and I still don't really understand it. From [here]( URL_3 ), credit to u/agate_ : "The Maxwell equations provide a conceptual underpinning for all electric, optical and radio technologies, including power generation, electric motors, wireless communication, cameras, televisions, computers etc. Maxwell's equations describe how electric and magnetic fields are generated by charges, currents, and changes of each other. One important consequence of the equations is that they demonstrate how fluctuating electric and magnetic fields propagate at the speed of light. Known as electromagnetic radiation, these waves may occur at various wavelengths to produce a spectrum from radio waves to γ-rays." Futhermore, * Max Planck found that energy is not continuous but quantized—meaning that it can only be transferred in individual “packets” (or particles). Each of these energy packets is known as a quantum. * This discovery led to the revelation that light is not only a wave, but can also be described as a collection of particles known as photons. [Source]( URL_0 ) **Why are electromagnetics waves, waves?** * A wave is a disturbance that travels through a medium from one place to another. Waves are formed by the vibration of the object or substance that carries the wave. "Waves" are just another way of saying that one medium displaces another medium over time. [Source]( URL_4 ) Electromagnetic waves originate from a vibration of an electric charge. Credit to /u/DrKobbe **Does light have different speeds depending on the medium?** * An electromagnetic wave can travel through anything - be it air, a solid material or vacuum. It does not need a medium to propagate or travel from one place to another. [Source]( URL_2 ) * Light travels more slowly in water and glass (and other materials) than it does in air. It changes wavelength when it goes from one medium to another. * Frequency cannot change. * The light transfers momentum and energy to the object it is traveling through, and then it gets that momentum and energy back when it exits. * The light has the same speed in air regardless of whether it previously traveled through glass or water. Otherwise we would see light traveling at all different speeds depending on what materials it has traveled through, and we don't see that." [Source]( URL_0 ) | The electric field and magnetic field define for every point in space a vector. So if you have a negatively charged particle(like an electron) you can imagine that in the space around it there are vectors pointing away from it. When the electric field changes that causes the magnetic field to change too, and vice versa. That is why often it is just called the electromagnetic field. You can generate waves in this electromagnetic field for example by rapidly changing the voltage on a wire. The voltage generates a electric field, and the change in the field moves away from the wire with the speed of light. A single small wave in the electromagnetic field is called a photon, and if the wave is in the right frequency we can see it. | 3 |
6e3j0g | Technology | How do my Google searches on one device show up as Facebook ads on another device if neither device are connected in any way? Here is the scenario: I have a work laptop and my Android phone. I search for a very obscure and specific thing on my work laptop and it shows up as ads on my Facebook app. Here's the kicker: There is no connection between the devices i.e. I dont use any personal emails or social accounts on my work laptop so there is no profile on there to connect me to my phone, nor do I connect my phone to my work network. How did they curate ads to something I searched on my worklap to my phone almost immediately? Keep in mind the ads are extremely specific and in no way is this a coincidence. | Big Data is tracking you and connecting everything they can get about you. The more data they have, the better is their conclusion of who you are and what you do. Your phone revealed your identity and frequent whereabouts as / u/ EasternSons/ / u/ EasternSons/device/yourphone / u/ EasternSons/location/work / u/ EasternSons/location/home. If they also have enough data about / location/work/u/ (all), they can identify and eliminate other / u/ (all)/location/work/device/(all) and conclude: / u/ EasternSons must be the one doing only work related stuff plus /interest/this-obscurity with / u/ EasternSons/location/work/device/yourlaptop. / u/ EasternSons/interest/this-obscurity. Now they make their ad network starts sending /interest/this-obscurity tagged ads to / u/ EasternSons/device/yourphone to make you buy the advertised item. They could even send it to location/work/u/(all)/device/(all) because it's very probably work related and they want all of your coworkers to buy that thing aaand / u/ yourboss might want a word with you about wtf you're doing all day. Edit: accidentally made some unwanted links, added spaces into /u/ to / u/ | 9 |
ccclol | Physics | how jumping in to water from a high place is a suicide I saw a post about man saving a woman from committing a suicide from a bridge and then there's the Etika thing. How do people die from jumping into water from a high place? Is it the wrong position they're in or do they just drown or what? Maybe i'm just stupid. | Even though its just water, imagine theres a hard "floor like" object on top of the water. This is called Surface Tension. I'm not as knowledged to explain it well, but I found a pretty good short summary of it. Objects that are just small enough to obtain a relatively high terminal velocity and just large enough to require significantly more kinetic energy to break surface tension, fail to break surface tension and thus, experience the reactive force of surface tension equal to the force applied to the water through kinetic energy. [Link for Summary]( URL_0 ) | 6 |
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 directed here. How does buying and selling stocks work? What is short selling? What is a short squeeze? What is stock manipulation? [What is a hedge fund?]( URL_0 ) What other questions about the stock market do you have? In this thread, top-level comments (direct replies to this topic) are allowed to be questions related to these topics as well as explanations. Remember to follow all other rules, and discussions unrelated to these topics will be removed. **Please refrain as much as possible from speculating on recent and current events.** By all means, talk about what has happened, but this is not the place to talk about what will happen next, speculate about whether stocks will rise or fall, whether someone broke any particular law, and what the legal ramifications will be. Explanations should be restricted to an objective look at the mechanics behind the stock market. EDIT: It should go without saying (but we'll say it anyway) that any trading you do in stocks is at your own risk. **ELI5 is not the appropriate place to ask for or provide advice on stock buy, selling, or trading.** | Is trading of GME stock allowed on TD Ameritrade currently? I've already put money into it in anticipation for tomorrow's open but I'm afraid that I'll be restricted from buying tomorrow morning. | 489 |
hva5ga | Physics | What is that circle or “halo” of absent light in a flashlight’s beam? | Do you mean the old incandescent lights with the dead spot in the middle like this? URL_1 It's because the bulb is relatively weak and the light uses its reflectors to create a wide 'flood' pattern to illuminate as big of an area as possible. That dead spot in the middle is an area that the circular reflectors around the bulb miss because they're designed to spread the light around evenly. A lot of modern LED flashlights have the opposite problem, where their reflectors are set up so they output light in a pattern like this: URL_0 That's usually far too bright to be useful up close, but looks great in marketing materials where the manufacturers can claim their lights are powerful enough to illuminate things very far away. Ideally, for a light to be useful for the distances most people use a flashlight, you'd want something set up so the reflectors output an even light pattern. That usually means you'd have to pay a bit more to buy a light from a company that emphasizes more than just pure lumen output. | 1 |
mm2oiu | Physics | -How does the atmosphere stop the oxygen from leaking and spreading out into space? | So some of the previous answers are close, but not complete. The earth is constantly streaming atmosphere into space. Part of the issue in this topic is defining exactly WHERE the earths atmosphere ends. The generally accepted definition for "space" is 100km. The problem is that our atmosphere doesn't just stop there, it extends above that. The International Space Station orbits at approx. 400 km. It has to periodically reboost its orbit because it is slowed by atmospheric drag. Yes, atmosphere at 4x the height space starts. Basically, the atmosphere isn't like the ocean, it doesn't just stop at a definite point. It fades out. So eventually there is a point where the "atmosphere" becomes indistinguishable from solar wind. Check out this wiki article for some of the different methods atmospheric loss occurs: [ URL_1 ]( URL_0 ) Edit: To add, the amount of loss is overall very small. A few kilograms per second. Current approx. total mass of the atmosphere is 5,150,000,000,000,000,000 kilograms. So we have plenty of time. | 4 |
9ytj44 | Technology | How does GPS work in poor weather conditions when satellite radio and TV don't | In order for GPS to work optimally, your receiver needs to have 4 satellites connected (some models will indicate the number on the display). While less than optimum, you can get location with fewer than 4 satellites, but the accuracy will be diminished Having to connect to multiple satellites for GPS provides a redundancy that can overcome some situations like weather; if you lose connection with one of the satellites, the other 3 can still provide information. When you connect to satellite radio, you're only connecting to one satellite, which provides no redundancy for the signal. | 3 |
eyv7ox | Biology | What's the physiological cause of Restless Leg Syndrome? Why does it feel like I need to move my legs constantly when it's happening? | The quick and dirty is we aren’t exactly sure what causes it. There has been some associations with iron deficiency, dopamine levels, and levels of other chemicals in your brain (Nothing I’ve seen on magnesium). If we knew exactly what caused it, it would be easier to treat. It’s called restless leg syndrome simply because people describe their symptoms as you have “the need to move your legs constantly” usually with that urge momentarily being relieved after they do it. If this is a problem for you, please see your doctor about it. Do not get medical advice from unverified people on the internet. | 2 |
82kj2d | Other | How do those "self-healing" cutting mats work? I bought a cutting mat for art projects and it said self healing, so I made a small cut it with a knife and days later it was completely sealed and it just left a scar. | The mat is full of polymers and chemicals that, when exposed to air (like when they're cut), they expand and chemically fuse together again, allowing the material to "heal." Once all the embedded reagents are used up (if it's cut many times in the same place), it will no longer heal. | 1 |
cubawf | Biology | can critters with exoskeletons (eg spiders, crabs, insects) feel things touching the exoskeleton? | Yes and no. No, because the exoskeleton itself does not have nerve endings. Yes, because the exoskeleton will push against the nerve endings in the tissue beneath the exoskeleton. If you touch the exoskeleton lightly, they won't feel it, but if you press hard, they will feel it. On another note; some critters with exoskeleton have hairs protrude the exoskeleton which can pick up the pressure. | 9 |
aihs8r | Physics | Why does pushing down on a sharp blade not cut you, but a slicing motion does? I was thinking about when people are cutting apple slices and stop the blade with their thumb. That doesn't cut you, but a slicing motion with a much lighter pressure does. I know to a point if a knife is being pushed straight down onto your thumb it would go through, but its more pressure then slicing. How come? Thanks :) Edit: Thanks for all the answers, really awesome! Just to clear up some confusion, I'm not saying pushing down on a sharp knife can't cut you, just it take more work then a slice. For example It's easier to cut into a chicken breast with a light slice then pushing straight down to cut. Sorry for any confusion and thanks again! You guys are a cut above the rest ;) | How does cutting skin even really work on an atomic level, since the knife atoms and our tissue atoms can never truly touch? a persistant /r/showerthoughts for me. | 12 |
6wvvlb | Culture | is the "alpha male" role a myth? From what I read the internet seems to be pretty split in their views on this. | In humans? Yes. In some pack animals, there does tend to be an "alpha." In humans, "I'm alpha" means "I recognize that if I act dominant, others will go along with it. That means I get to be a dick to whoever I want and praise myself for it." | 5 |
5w0dbe | Physics | If the Sun suddenly disappeared, how long would it take for all life to end and what would it look like? | There's some good answers here regarding what happens on Earth as a result of no light or heat, but there's a much larger problem: gravity. If the Sun suddenly disappears, Earth is no longer in its orbit. Not such a big deal: we cannot leave the Habitable Zone where liquid water happens if said Zone no longer exists. The cold is still a problem. The real worry for me is what happens to the minor bodies: asteroids and comets. For the most part, asteroids hang out in the Asteroid Belt between Mars and Jupiter. This is, however, a simplification. There's quite a few asteroids closer to the Sun. There's also a bunch in gravitationally stable points on Jupiter's orbit (they're called Greeks and Trojans) [A wildly simplified picture] ( URL_0 ). There's also a bunch of comets that have no particularly defined region; they're just kind of all over the place. Asteroids are mostly in the same plane as the rest of the solar system (the ecliptic), but comets can be far above or below that plane at any given moment. Gravity keeps all of these things in orbit around the Sub. Gravitational effects travel at the Speed of Light. If the Sun magically winks or of existence, none of these things are bound to their orbits anymore, and they'll start zipping off at a tangent to their orbit as soon as those effects reach them. This means Mercury starts wandering off in 3.2 minutes. Venus at 6. Earth at 8.3 and so on. Here's something else: things close to the Sun move faster, because the gravity pulls them really hard. In the case of comets, they get super-quick and come around the other side with enough force to fling them billions of miles before they run out of steam and are pulled back again. So the things closest to the Sun are moving the fastest. And they're also the ones that will be affected by the Sun's disappearance first. Space is big, and the Earth is relatively not big, so we're not a huge target. But we are suddenly talking about a bunch of stuff shooting all over the place at very high speeds. Things that were in stable orbits to never hit Earth are no longer in those orbits, and neither is Earth. And they're not easily predicted either, because any time they get close enough to another object, both paths will be altered slightly be gravity. That's bad enough for the stuff near the Sun. Wait until it hits the Asteroid Belt. Jupiter is 40 light minutes from the Sun. That means that in less than an hour, our neighborhood of space has become an utter chaos of ballistics. In less than 6 hours, the effects reach the Kuiper Belt, where there's a lot of stuff that's a lot bigger. Now, none of the stuff in our neighborhood is huge, except the planets. In diameter, Ceres is a bit smaller than Texas, and that's by far the biggest asteroid. Many more are the size of a skyscraper or a few city blocks. But when these things are traveling at, usually, well over 40,000 miles per hour, they carry a big punch. Destruction of the dinosaurs at Chicxulub? Asteroid the size of San Francisco. Something the size of comet 67P (downtown LA)? There goes North America. Stuff the size of your house? Goodbye most of a city. Ceres or Vesta? Repave the planet with a new crust. If the Sun disappears, we're looking at a brief but intense bombardment that could destroy huge portions of this planet's surface. Or none of them could hit us, and we have exactly the same scenario as everyone else is saying. | 6 |
crzn7i | Physics | When an infrared non-contact thermometer is pointed at a target, how does it measure the target's temperature and not the temperature of the air column in front of the target? | While most of the other answers are much more detailed and correct, here is a very intuitive way to understand it: When you take a picture of something with your phone how does it capture the objects in front of it instead of the air? Because the air is transparent in the wavelength you are capturing. This isn't a perfect metaphor, but it is probably the simplest metaphor. | 4 |
lgz7fw | Chemistry | Can I use shampoo in place of body wash? | The answer to this, is yes, if you like the results. Everyone's skin is different. Our skin is different in how thick it is, how quickly it sheds, how dry it is, and how much oil we produce. Because we are all different, everybody needs just a little bit different care than other people. Most of our shampoos, conditioners, soaps, lotions, body washes, scrubs, and so on are tested against a sample of people and are then adjusted in little ways to get better results with whatever group they decided to test the product. This means that not every product is going to actually be good for every person. That's why there are shampoos specifically targeted to those with Asian, African, or Middle Eastern/Indian backgrounds here in the US-- because most of these product testers are assumed to be "typical" people, i.e. Caucasian people in the US, who have very different needs than other people around the world. So that means that, if you're a dry skin guy, but the product you used happened to be tested on really oily people, it might be too strong for you and might make you end up drier and itchier. But if you're very oily, or work around a lot of dirt and grease all day, you might find that a gentle shampoo does just about nothing for you. This is also why most people shouldn't use body wash on their hair-- skin on your head is more sensitive than the skin on your body, so chances are, the body wash is too strong for your head skin. So basically, try using your shampoo as a body wash and see if it works out. If you're happy with how clean you feel, if your skin stays healthy, if you aren't too oily or too dry and you don't break out in pimples, redness, or rash, then it'll probably work for you. But if you do end up with a result you don't want, then I would say try something else. | 8 |
l8hov6 | Other | Why is Shakespeare considered to be one of the best writers in history? | I feel like a lot of movies and shows are based on plots from his plays. He also invented a shit ton of words we still use today below is a list of some of them URL_0 | 8 |
ehufs5 | Biology | why do tree rings add up to years? Why doesnt each ring occur / form over 200 days or 500 days or etc? Why a year approximately? | Most trees go through cycles of all kinds. Growth cycles are common. You can really see them on all sorts of pine and other coniferous forests (not to be confused with carnivorous, coniferous means a forest composed mainly of trees with cones that drop for reproduction and needles). During the late spring and early summer, if you look on the ends of the pine needles, you can see a more flexible, lighter green bunch of pine needles. This is an example of their cycle growing. After they grow these new very small extensions of their branches, they will go dormant for the winter. This includes the thickness of the trunk. It slowly adds layers upon it every summer, in a cycle. | 3 |
crhei4 | Biology | Why is it so hard to stay awake or keep your eyes open sometimes, even though you've got more than enough sleep? | Sometimes oversleeping will actually cause you to be more tired so that could be one reason. Another reason could be that you think you are getting a good nights sleep when perhaps you are actually narcoleptic or have some other underlying medical condition. I don't think it should typically be difficult to keep your eyes open or stay awake when you are getting a normal healthy amount of sleep and haven't stayed awake for too long. | 3 |
8yym7c | Biology | Why do doctors wait until they suspect cancer before sending someone for an MRI/CT scan instead of having a scan done at 40 or 50 years old the same way prostate exams and mammograms are recommended? | Other people have already pointed out the cost and radiation exposure. Another factor to consider is incidental findings. If take 100 people and give them all a full body scan, you'll probably find some weird-looking thing in at least 20 of them. This guy has a thing on his kidney which could be a benign cyst or it could be a cancer. This lady has some stuff caked onto the ovaries, could be ectopic endometrial tissue but could be cancer. This guy has a lump in his abdomen, could be a meckel's diverticulum but it could be a cancer. Maybe two of the people with a weird finding actually have cancer, and one of them is probably too far along for it to be helpful to have found it now anyway. Meanwhile, the other 18 people who turned out not to have cancer just ended up having unnecessary surgery. With those 18 unnecessary surgeries, two had severe post-operative complications, one of whom died, two are now pooping into a colostomy bag, one is impotent, one is infertile, and two now have chronic pain. So overall we've maybe saved one life, but also lost one life and substantially messed up several others. Overall, it appears that this group of 100 people is worse off for all having gotten a scan. | 7 |
6ypah5 | Economics | Why does the end of the financial year not coincide with the end of the calendar year? | Retail businesses often do the bulk of their business between Nov-Jan and it would be really inconvenient for them to have to close their books on 12/31. Government agencies have budget years that are dictated by statute, so their fiscal year typically coincides with their budget. Other cyclical businesses will want a fiscal year that closes during one of their down periods. Finally, for everyone else, having a fiscal year close on 12/31 usually means your accounting staff has to work move during the holidays, which is rarely popular. | 2 |
70xefn | Repost | Why is Mexico so underdeveloped compared to the US and Canada? | Cartels control the police in a number of places (not gonna estimate), multinational corporations exploit the poor, and governments (intentional plurality) suggest it's the citizens faults for the state of their nation - effectively sidestepping responsibility or understanding. | 4 |
gzezc1 | Biology | What causes placebos to trick our brains into thinking they’re effective? | Our brains predict the future all the time because it allows you to think through possible reactions and find the best one. If your body predicts extra energy it sees the best reaction as working harder to efficiently use that energy. Our body actually throttles back our energy to try and save it, so it can easily give more if it thinks it’s a good situation to do so. This story is similar for almost all placebos. | 2 |
a4mjle | Economics | Why do all units of measurement come after the numerical quantity, save currency which comes before? | Note that this mostly only done exclusively in English speaking countries. It is easy to see in Europe: Ireland uses €50, while France, Germany, Italy, Spain, Greece, ... use 50 €. | 3 |
jwb91n | Other | Why did portraits of people’s faces all look so poorly-done up until the Renaissance? | Renaissance paintings were all about the ideal portrayals of the human body. Part of the art style of the Renaissance, especially with artists like da Vinci, was the idea of sexless beauty. So, they'd often make portraits of people with androgynous features. Another part, such as the work of Michelangelo, would have portrayals of very toned and muscular people. Botticelli liked to draw disproportionate humans performing impossible poses, but still portrayed his idea of a "perfect human". Artists weren't always striving for realism. Realist art is actually fairly new. Medieval art was all about symbolism and color coding, Renaissance art, as I said, was all about the ideal "perfect people". | 2 |
7a72tt | Repost | What is subnetting? | It's a way to divide up the IP addresses of the Internet so everyone can find them (4+ billion of them on the IPv4 Internet). Every computer, phone, etc, can't keep track of billions of addresses and how to reach them, so grouping them into subnets is necessary. It's like phone numbers - +1 (555) 555-5555. The +1 means the U.S. The (555) is an area code (or NPA) inside the U.S. The 555- is an area within that area code (NXX). And then the 5555 is one of 10,000 possible phones in that area. If I make a call to my local NXX, the local switch knows where all those numbers are. If it's not in my local NXX, but it's in the same area code, it can send it to a nearby switch that would know where those 10,000 numbers are. If I call out of my area code, the local switch doesn't need to know all about the number, but will know from the country code or area code that it should send it to a long distance provider / switch. Dividing up the address space is necessary so everyone doesn't need to keep and update a list of billions or trillions of numbers and where to find them. You keep track of your local numbers and make sure everyone else knows that you've got that block of numbers so they can reach you. | 1 |
kqqqf8 | Physics | what happens to matter in the "Big Freeze"? | A brief overview of the "big freeze" is required. Currently, matter *exists.* Hydrogen is the simplest atom in the universe and therefore the most abundant due to it's ease of creation. All of the stars fused hydrogen into helium and continued this fusion down the periodic table of elements until they reached heavy metals like iron. At that point, the first stars in the universe were exploding into massive supernovae that put all of these heavier elements into the universe. Billions of years pass and eventually planets are being formed from these other atomic materials. Gas planets, solid metallic planets, icy planets, etc. A supernova is like a tree rotting in the forest. The tree may have died, but the nutrients that it leaves behind allows for other trees to grow and thrive. But eventually, the elements are so dispersed that they can no longer come together because of gravity. By this point, most stars have either exploded into supernovae themselves, turning into black holes or neutron stars, OR have swollen and then shrunk down to white dwarves. At this point, far far into the future, there isn't enough material to create new stars. Stars continue to radiate their heat energy very slowly and eventually are the same temperature as the vacuum of space. Neutron stars take longer to reach equilibrium and black holes even longer, through hawking radiation. But *eventually,* when all of the celestial bodies in the universe have reached the same temperature as the vacuum of space, no new stars are being born, and nothing else happens. The matter still exists, but is so evenly distributed that it is essentially frozen. This is the idea of entropy. Gasses in a bottle don't clump to one side, they spread out to fit the container they are in. If you consider all matter in the universe to act like a gas (because we know the universe is expanding) then eventually it'll just be so evenly distributed inside the container of the infinity of space that particles will no longer interact with each other. That was a wordy explanation, let me know if you've got other questions. | 1 |
e1ysvx | Biology | Why can’t you donate blood or organs if you have lived in Europe in the 80’s? | This has a rundown. It’s not just Europe. URL_0 | 5 |
io34so | Mathematics | Explain calculus like I'm Five. | Calculus is the mathematical school regarding change in a system over time. Basically Calculus is to change what geometry is to shapes. | 1 |
8tuzk4 | Mathematics | Statistical P value in context I work in precision metrology and I helped a customer perform a correlation study between two pieces of measurement equipment. One of the devices is the gold standard of the industry, and one was an unknown. I helped him measure 60 parts on both devices and sent him on his way. He later told me both devices correlated with a P value of 0.002. He was happy with this, and felt that the vendor who owned the gold standard machine and the unknown machine both gave good values, validating both sets of results. I did some googling, and I understand that P represents the relationship between total randomness and total certainty, but in this instance, we were comparing a bunch of parts with a range of ~10 microns. How does that work? | So basically, if I understand correctly, he took 60 measurements with each of two devices. What he did was the following: He calculated the sample mean and sample variance for both sets of measurements He then said "let's assume that there is no difference between the performance of the two parts on this task, what is the probability of observing the sample means we did?" As it turns out, this is not too hard to calculate rigorously. Under the assumption that the two sample means should be identical, the difference between them will be drawn from a t-distribution with a mean of 0 and a variance of (sample variance 1)/60 + (sample variance 2)/60) with 118 degrees of freedom. All this means is that the sample means are drawn from a probability distribution with very particular properties, such that you can calculate the probability of any particular observation (I can explain why it takes this particular form but it will make this explanation a bit longer and more complicated). So he calculates the probability of observing the difference between the two means he actually observed under the assumption that they should be the same. If he observes a huge difference in performance, it would translate to an extremely small probability that the two parts actually perform the same. The p-value is the probability of observing the difference in means that you do assuming there should be no difference. A p-value of 0.002 would imply that the other device performed very differently than the gold-standard one. As the customer implied they perform equally, I'm either misunderstanding the situation or the customer has a very strange way of thinking about this problem. | 2 |
emt021 | Technology | How does a surface to air missile battery mistake a large airliner for a fighter jet? | It happened before. During the last Iran-Iraq war (when the US was still on the side of Saddam Hussein) an US warship shot down an Iranian airliner under very similar circumstances. It probably has a lot more to do with seeing what you expect to see than with anything technical. Get people into the mindset that they are going to be attacked and they become too trigger happy for everyone's good. | 3 |
doidev | Economics | Why can’t we just take all of the plastic and garbage that’s in the ocean and throw it in a volcano so it can melt and be destroyed? | And even if we could collect it all and burn it in a volcano, it would just turn into air pollution. It's not any different than using an incinerator. | 2 |
dugmia | Economics | how can a company have assets and cash totalling $20m, liabilities of $10m, and a net worth that's in the negatives? | By definiton this can't be true, so if you're confused then either a) the accounts are wrong, b) you are reading them wrong, or c) there are unlisted assets or liabilities which are affecting the "net worth" figure. If a) and the accounts are wrong, then the FD should be sacked because the capital equation is the first thing any accountant or business student learns. If b) and you are reading them wrong, the company might have a Statement of Changes in Equity on its financial statements which might point out what is amiss. Otherwise, the "accounts summary" you are looking at might not be the statutory financial statements. In most countries this is public record, so have a look at your company's statutory accounts and compare them to the summary you have. There might be a mismatch. If c) and something is omitted, again this is highly suspect and the FD should probably be sacked. I suggest you ask around about lease agreements, long-term liabilities which might be left off, or pension arrangments. For many companies pension liabilities can be a huge factor but are often left out of operational accounting summaries because they are technically separately owned, at least in the UK. | 3 |
blznv2 | Culture | What's the point of including "silent letters" in words? | The pronunciation of the word changes. Knight used to be pronounced: k-nigt. Spelling always lags behind how words are peonounced. | 1 |
cn79ea | Biology | How do squats exercises naturally release testosterone? | I know this doesn't answer the question, but all resistance exercises spike testosterone. Squats just release more because they activate such a large muscle mass. | 3 |
javk7e | Technology | How come mobile phones fast charge only with their respective company's fast charger even if we use a different charger with more watts | It depends on the method and hardware they use in the device for fast charging. If they use a standard (something like Qualcomm's quick charge), then any charger supporting that would work. | 2 |
6tzwly | Biology | Do newborns feel any pain as they are pushed through the mother's vagina? They always cry, but is that because of the shock of the new environment or the high amount of pressure on their skulls? | Newborns cry because they are using their lungs for the very first time and it hurts. I don't think the head trauma is too bad, that seems like something evolutionarily accounted for. | 2 |
5vi0m3 | Other | Why is the majority of girls handwriting nicer looking than boys? | What's your source that men have worse handwriting? I'm a teacher and I wouldn't say that's accurate, but I don't have any real data. | 42 |
917hox | Technology | Why, when you’re on slow wifi, will ads load before the content you actually want to see? | The web site is programmed to send the ads before the content. Otherwise, you'd be less likely to see the ads, and their customers would be unwilling to pay for the ads. Remember, from a web site operator's perspective, the purpose of the site is to show the ads. | 1 |
63hdi6 | Physics | Growing up my mother always told me to never start a pot of boiling water from hot tap water only cold. What's the logic behind that if any? | The water comes into your home drinkable. How it gets from that drinkable state, to your faucet and into your glass, matters. Water is a solvent. Put it in contact with many different materials like copper, lead and tin and it will tend to leach those elements into the water. The ability to do this goes up with temperature. In addition to that the hot water heater is a place where sediments and minerals are deposited and over the years they build up until the hot water has large amounts of dissolved metals and minerals in it. It's not exactly unsafe to drink, but it affects the flavor of anything you make with it and over time you are going to get a lot more exposure to metals and minerals in your food. A hot water heater is not a coffee maker. It does not heat the water up so that you can enjoy a cup of tea. It is not a clean system, it is there for utility like clothes washing, showers, and other non drinking uses. You could also choose to drink water from a garden hose, but it is a little more apparent there, that what the water moves through imparts a taste to it. Namely the taste of garden hose much like the taste of water heater. | 31 |
9jdl11 | Chemistry | The importance of using soap when doing the dishes. | The soap is made up of hyro-phillic particles, which attract water, and hydro-phobic particles, which attract grease/oil etc. When applied to the dishes the grease/oil will wash away with the water instead of staying on the dish as water and oil generally do not mix. | 2 |
ni0how | Technology | How are software update numbers assigned, for example version 22.13.001 vs 22.14.001 vs 23.01.001... what would be required to change one number vs the others? Edit: Also forgot to include in a scenario where you have 22.13.002 vs all the others | No hard and fast rule. The "small" numbers (ie to the right) are typically assigned to bug fixes, minor corrections - eg spelling errors, window size corrections etc The "middle" numbers are for minor content tweaks. For games, these are things that affect gameplay but in not a major way (like adjusting a character power, speed etc). Sometimes releasing new content. Typically these changes are fairly seamless 22.001 will work with 22.002 etc etc. The "major" rev numbers (ie to the left) are usually major changes to the software. It will probably have significant impact to the user. Usually not done very frequently - for stable software, it could be years. The major revs can also introduce incompatibility. So rev 22 might not work with rev 23. | 3 |
93ydy3 | Economics | What are the causes of economic inflation? | Inflation occurs, primarily, when a country creates more money than it creates in value. Believe it or not, value is not a zero sum game. Anybody who discovers a way to more efficiently use resources such as lessening costs of production or inventing a product which hasn’t existed before in a way that increases utility creates value (or wealth) for a society which didn’t previously exist. This is why (generally) governments print money, to try and keep the value of money steady by printing proportionally to the new value that’s been introduced to society. ————— Some other causes for inflation are fluctuating exchange rates which change the nature of imports and exports from a country (the cash in versus out of a country), or a host of other things such as shortages which temporarily increase demand of which prices may stick for a while afterwards. Some other causes for governments printing money include quantitative easing, an advanced economic concept that posters inflation tends to lag behind a cash influx so printing more money may provide more short-term relief with minimal to no long-term consequences, or currency devaluation in which a government prints way more money than the country creates in economic growth for purposes such as paying back foreign debt. Also a host of other things. See /u/lollersauce914’s comment [here]( URL_0 ) for more examples. | 1 |
nxjgyq | Biology | How do bees get back to the hive when it starts pouring rain if they can’t fly in the rain, especially when it keeps raining for days and days? | African bees can handle the rain actually, as well as their hybrids (which is why the hybrids were made in the first place. They're hard working bees!) Bees predict the weather better than meteorologists! | 4 |
7k63y4 | Biology | Why do humans have dominant hands? Do other species have dominant sides as well? | Yup on the other species: Polar bears are all leftpawed. Nobody knows why. Doubt there is an explanation for humans, but hopefully someone comesin and proves me wrong! | 8 |
92v9af | Other | Why do mountains have a gray, hazy appearance from a distance? | The atmosphere (the air) is in the way and scatters the light. This causes the haziness (which usually is slightly blue). Photographers used to use a "skylight filter" on their cameras, which is a slightly "warm" filter, i.e. it reduces blue a little bit in the pictures (with digital camers, you can fix the blueish tint on your computer). Interestingly, this haze due to the atmosphere caught people out a bit when they saw the pictures from the moon landings - there is no atmosphere on the moon (edit: actually there is one, but barely), so there is also no haze when you look at distant mountains. This makes things which are several kilometers away look to our brain as if they are only a couple hundred meters away, because the haze is missing. For example, the mountains in the background of [this picture]( URL_0 ) are several kilometers away (and several hundred meters high). | 4 |
hvwzys | Physics | Why can't we dig deeper than 12.2 km into the earth? Knowing that kola superdeep is the deepest we have been able to achieve with current technology, I understand the pressure and heat aspect of attempting to drill or bore to those depths and the limitations imposed by those conditions. Why couldn't we theoretically just blast our way down with dynamite creating a large enough space with every blast to allow for the pressure and heat to dissipate, while simultaneously allowing for the removal of the debris (not sure if that's the limitation). Wouldn't you then be able to endlessly lay new charges at the new floor with every blast, allowing us to reach whatever depths we wanted? | URL_0 this YouTube video explains the deepest hole ever dug and explains why it didn’t go deeper. | 4 |
d4xesk | Technology | Why does the same website sometimes load lighting fast with just 1-2MB of download speed and other times struggle to load up all the way with 10MB+? To clarify...where I live I have 1-4MB depending on the day but often it works just fine, with every website popping up immediately. So it surprises me when I am overseas at a hotel or cafe with 10-20MB of speed that the internet can often lag a bit. I can tell a big difference when streaming but not browsing. Perhaps it's related to the number of people logged into to the same WiFi network...actually, I am sure that's it now that I think about it but I'll ask anyhow. | Imagine the internet like a pipe system. Some pipes are big and can carry lots of data, others are smaller and can carry less data. Some pipes are pretty much straight from the server you're accessing to your computer with little in the way, others will twist and turn, maybe even go to multiple other cities until they reach you. That impacts latency. Some pipes can also be leaky and when your data "leaks" the server might need to send the data again. This is known as packet loss. What the speed your internet provider tells you is just how big the pipe coming into your home is and the speed of the internet your computer reports is how big the pipe coming into it is. That has nothing to do with the distances the data has to travel (latency) or the leakage of the pipes (packet loss) and all 3 of these impact how fast a website is loaded. Also, as you said, on crowded WiFi networks things get a bit more complicated. Imagine the WiFi router as a boss that orders a waiter (the antenna) to fetch and send orders from/to clients (the devices). What you might notice is that if there's a single antenna there's only a single waiter that has to serve multiple devices. So if you start doing a speed test which measures how fast a big file can get to your device the waiter will do a few trips to your client with very big orders. But a meal(website) may have many many small plates instead. So in order to receive all of them you'll have to wait for the waiter to complete the other clients' orders multiple times before your entire meal (the website) is at your table. There are other things like caching (in the meal analogy, imagine you have a fancy 3D printer for meals so if you feel like eating the same thing you've already had you can make it again without having the waiter serve you), fancier routers with more antennae (i.e. more waiters), ad-blocking (either telling the waiter "don't bring me anything containing gluten(an ad)" or the waiter bringing you something containing gluten but you throw it in the trash immediately), etc. | 5 |
80l0l8 | Other | how are people able to track hackers ie: where they are, who they are, etc | On the computer side, attribution is insanely difficult to do properly. Agencies have thousands of people working to track the big threats. Ultimately it comes down to behavior and pattern analysis to make a best guess. Someone can always be masquerading as another actor. The other part is that you never rely on single source intelligence. Tracking the "hack" is unreliable at best. Having someone in a consulate steal documents like a memo from one military leader to another discussing the attack provides more reliability. For average Joe hacker, the FBI doesn't just look at ISP logs. They confiscate his equipment and run forensics on it looking for multiple sources of proof. | 8 |
j2dy2d | Biology | We have a lot of liquids in our bodies. Why can we never feel them sloshing around? | Fill a water bottle all the way to the top so it’s pretty much spilling over and put the lid on, it might slosh a little bit it’s a lot harder to tell than if it’s half full. Your body doesn’t have much air mixed in with the liquids and your blood vessels have valves and can tighten to prevent blood from draining to other parts of your body when you move around. | 13 |
dq76uf | Other | Why is factory farming bad for the environment and how bad is it in comparison to fossil fuels? | It's unsustainable for the environment. When you're in a factory and are basically make a fixed amount of animals regardless of the situation, you need to increase the rate at which you do things which will destroy the environment. > The process in which feed needs to be grown for animal use only is often grown using intensive methods which involve a significant amount of fertiliser and pesticides. This sometimes results in the pollution of water, soil and air by agrochemicals and manure waste, and use of limited resources such as water and energy at unsustainable rates. You end up putting a huge number of animals in a small space and the results are not only detrimental for the environment, but for humans as well. > On intensive pig farms, the animals are generally kept on concrete with slats or grates for the manure to drain through. The manure is usually stored in slurry form (slurry is a liquid mixture of urine and feces). During storage on farm, slurry emits methane and when manure is spread on fields it emits nitrous oxide and causes nitrogen pollution of land and water. Poultry manure from factory farms emits high levels of nitrous oxide and ammonia. With these farming emissions, they also leak to surrounding groundwater and can make people sick. | 1 |
ald8bz | Physics | How does the earth spinning on its axis not slow down or lose momentum? | Without some sort of friction something that is moving, keeps moving. To slow anything down you need to transfer energy and do work. So an object spinning about its own axis in complete isolation and a hard vacuum will not slow down since there is nothing to slow it down. Earth spinning on its axis does actually very slowly slow down, due to the gravity of the moon (and to a lesser degree the sun) causing tides which slows down the rotation. (The moons rotation has already been slowed down this way so that it basically no longer rotates with respect to the earth.) Some other stuff also help slow the earth's spinning a tiny bit, but the earth is a really huge spinning thing so that it takes extremely large things to really slow it down in a noticeable way. | 8 |
5xap5f | Other | military strength in Europe compared to Russia A few days ago, the Danish minister of defence said that NATO would not be capable of a serious defence against Russia without American support. I was looking at the numbers, and counting only France, GB, Germany and Italy Europe spends well over twice as much as Russia on military. Why can't NATO defend against Russia without the US? (I know that not all European countries are in NATO, but most are, and chances are all would support NATO if it came to that) | Oh buddy it's spreadsheet time! So I went over to [GlobalFirepower]( URL_0 ) and pulled up a bunch of numbers for all countries involved. I was disappointed I couldn't aggregate all of NATO together so I just used the 4 largest members minus the US and Turkey who's kinda iffy right now. So we have France, Great Britain, Germany and Italy as the bulk NATO force in Europe. We'll compare them against both Russia and the US on a number of important stats. So first. You are correct. Top NATO spends way more than Russia at 160.3 billion versus 46.6. Something interesting though is how long these places can keep paying for a military. Countries have reserves of cash and gold so I did up a bit of a ratio. NATO has a 4.18 ratio budget to reserves. So theoretically it has 4 years worth of cash on hand to pay for the army they have. Russia oddly enough has 8.11. (The US has 0.22). So Russia can theoretically keep a war going longer. So lets get into shooty bits. NATO has 855,000 troops ready to go right now against Russias 766,055. But Russia has a larger reserve force nearly 5 times NATO. 564,770 to 2,485,000. The US has 1.4 million regular and another 1.1 million in reserve. Fast and furious now! (NATO/Rus/US) * Tanks 1,824/15,398/8,848 * AFVs 25,652/31,298/41,062 * Artillery 1,352/14,390/4,564 * Fighting Aircraft 1,661/2,667/6,050 So Russia brings multiple times more guns than NATO. Much of it is still cold war era stuff but when they have any tank and you don't, it's still an unfair fight. NATO really needs the US to balance those numbers If we want to get into the navy we can but basically Russia doesn't have much of one and it's roughly the same size as NATOs and the USN blows everyone else out of the water with more carriers, destroyers and submarines. So the point is that NATO doesn't have much of a stand up army, because the US does. NATO has enough stuff to put up a fight but really needs the US to push back and actually win against a Russian invasion. | 1 |
6kql46 | Chemistry | - How do counterfeit pens work? Further, why do they mark skin as genuine? Like, I mark on my hand and the ink color signifies genuine "money" rather than counterfeit. | currency paper is a mixture of cotton and linen with no cellulose. The iodine in the pen reacts with the starch (cellulose) in lower quality counterfeit bills paper causing a dark stain to form. Genuine bills fail to react and the iodine evaporates after a short time. | 1 |
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. | As someone who's been on SSRIs, those things are fucking awful. While I was on them, I couldn't be satiated in any way (likely because that's partially what Seratonin does). Meaning, when I ate, I couldn't feel like I was satisfied or full. I often could orgasm, and when I did, it was dull and barely enjoyable. I would wake up clammy and sweaty. It was fucking awful, and I wanted to kill myself about a thousand times more while I was on them than I did before I ended up in the mental hospital where I was prescribed them. Honestly, I consider SSRIs an awful aspect of mental health today. I've seen so many people who were just told to medicate their problems, and I've yet to see them actually make anyone better (just more 'evened out', 'normalized'). | 65 |
65yj66 | Other | How were tickets for air transit purchased pre 'online' days? Randomly thought about it today, was it all done over the phone? Did you have to go out to the airport to buy a ticket for 2-3 months time etc.? | Travel agents! There were physical retail storefronts where you'd go, and a travel expert would help you plan and book your travel arrangements. You could also call an airline or travel agent and have them book the ticket. They would then mail you a physical ticket... I think some travel agencies had the ability to print them in their agencies, too. | 5 |
9bgsfh | Other | if someone knows how to play the piano, and sat down at a organ, would they be able to play the organ without any practice? | Have played both piano (for many years) and organ (just 1 or 2 yrs) so I have first hand experience. First, the obvious difference is that the organ has a pedalboard so you play the bass notes with your feet. Completely unique skill that you must learn from scratch. Secondly, the organ has stops (the knobs to the side used to change the sound). These aren't a huge difference because a lot of times you might just set the stops at the beginning of a piece and leave it. Thirdly, the organ has multiple keyboards, each of which can have its stops set separately, so each keyboard can have a different sound. But organs and pianos both have a keyboard, so if you didn't need the pedals or stops, playing the organ is just like the piano, right? Wrong. The action (how the keys respond) of the keyboard is different. The piano is velocity- sensitive and the keys have a weightier response. The organ keyboard feels more like a non-weighted digital keyboard. There is also no sustain pedal on the organ so if you want a note to hold, you must keep your finger on the key. With the piano you can cheat a bit using the pedal. So your fingering technique on the organ involves more finger substitution (where you switch which finger is on a key without lifting the key) and sometimes awkward reaches. On the piano a bigger part of the technique is how you strike each key, because that's where your expressiveness comes from. So, yes, someone who plays the piano could play the organ simply, but to be good at each instrument requires somewhat separate skill sets and ample practice on each. | 3 |
a4r2mk | Biology | What causes that 'gut feeling' that something is wrong? Is it completely psychological, or there is more to it? I've always found it bizarre that more often than not, said feeling of impending doom comes prior to an uncomfortable or dangerous situation. | Watch a deer eating in a field. They will graze, then suddenly hold their head up, scanning, smelling, and listening for danger before resuming eating. They do this hundreds of times a day. Almost every time there's no danger. Almost. Gut feelings help keep us alive, even with a really poor hit/miss ratio, and we tend to remember the hits vs the misses which reinforces our tendency to stay vigilant. | 22 |
5mefop | Other | What are the main differences between the Canadian government and American government ? | Canada has a parliamentary system, and so they have a prime minister, who is elected from among the parties within parliament itself. In addition, their upper house (the Senate, equivalent to the House of Lords in the UK) is appointed by the government, rather than elected by the population. In addition, like many parliamentary governments, the Canadian system does not have a president as head of state (the nominal head of state is the Queen of the UK). It's important to note that, while the prime minister functions as the head of the government, he technically plays a different role than the POTUS in that he is not also the head of state. | 1 |
6429vx | Biology | How/why does chemotherapy kill cancer cells, but not regular or healthy cells? | Many chemotherapy are designed to stop cell division (since a simple way to think of cancer is cells that don't stop growing, they divide more often than average across the body). By targeting key steps in cell division, these chemo drugs can kill a larger proportion of cancer cells than non-cancer cells. But some healthy cells divide often too (that's one reason hair loss is a side effect of chemo, hair follicles divide often, too). | 6 |
bcnqak | Biology | There are videos of fresh animal muscles twitching violently when salt is sprinkled on them. If marine animals experience a cut that reaches a muscle, do they react in the same way to the sea water? | Nearly every animal will reflexively twitch in the scenario you are asking about as this is an evolutionary protective response. However, I suspect what you're really inquiring about is how salinity affects the muscles of marine animals which have evolved to survive in a high salinity environment, likw the ocean. In short, the answer is yes - even a dead marine animal will move with salt applied to flesh in some cases as it is a far higher concentration than what said animal's body will normally contain. I believe their kidneys are evolved to actually remove the saline levels from ingested salt water to nearly the same level as non-marine animals. Really what's happening is the triggering of neurons in the muscles via a very well known biological mechanism for how neural cells create electrical potential for signaling you have studied in school, known as the Sodium-Potassium pump. Here's an even creepier video of a dish served in Japan which is made of a freshly killed squid which literally gets up and starts dancing when soy sauce is poured on it: URL_0 | 7 |
cg372p | Biology | Why is ingesting nicotine toxic but we can smoke cigarettes constantly? Excluding the fact that you'll get cancer likely, why is it that if you eat cigarettes or drink vape liquids, you'll get very sick? | If I understand correctly you are asking why eating a cigarette makes you immediately sick and smoking one doesn't. That's because breathing in smoke only sends the smoke into your lungs (for the most part) and that smoke and chemicals in the smoke get absorbed through the lungs. If you eat something it goes through your digestive system, where it is absorbed through the stomach lining, which generally doesn't take kindly to the chemicals in tobacco. | 3 |
7w27um | Biology | Why do young children cry so easily when getting hurt compared to adults who often don't cry at all? | Children don’t have the ability to assess how serious an injury is. They don’t know that a bruised knee isn’t actually a broken leg. They cry so an adult can assess and take care of the injury or tell them it’s ok. | 4 |
juhzgk | Chemistry | What are isotopes exactly, and why do they matter? What are isotopes made of? I understand that the process of nuclear fusion involves the mashing of isotopes, and that there are three types: protium, deuterium, and tritium. But I have no idea why there are three types, what they do differently, why they matter, and what they are made of. So, here's to me furthering my education. Thank you! | > protium, deuterium, and tritium. Those are names of the three different isotopes *of hydrogen*, the first having a nucleus of just one proton, the second a nucleus with 1 proton, 1 neutron, and the last a nucleus with 1 proton and 2 neutrons. | 3 |
i6ndqk | Biology | Why does drinking hot drinks after eating spicy food make the spice feeling worse, whilst colder drinks lessens the feeling? | First of all this is not fully true. The point is to drink something with fat in it because capsicin is lipophil. Like milk or yoghurt. Whereas water just spreads the capsicin over your whole mouth, because its hydrophob. Second point: the hotness from spicy food comes because capsicin docks on the cells that signal pain, especially it imitates the feeling of a burn in your mouth. Thus cold drinks might soothen it better as hot ones | 2 |
ih62p6 | Economics | How come food prices don't soar as insanely as home prices, yet there's always a demand for them unlike homes? Like, why can't people be "gentrified" from food? Sounds funny but I'm guessing housing is a luxury and not a necessity? Yikes. | Lets look at food. Food is being constantly produced and if the prices are increased, nobody will buy, putting you in a surplus. How do you get rid of food incredibly fast in this situation? reduce the price. Food prices go up and down in price all the time. In Australia, if there's a natural disaster in Queensland (tornado), the prices of some fruits skyrocket from 4-5 dollars for a bunch to 5 dollars just for the skin. (Supply and demand). & #x200B; Lets look at houses. Houses don't move. Houses remain where they are and even tho you can produce more houses they'll often be in undesirable locations, such as really far away from the city or anywhere you prefer to work. Too far away from a school or store. The public transport in the area is terrible. House prices are based on: What's near it. Schools close by? Increase. Stores close by? Increase. Good public transport? increase. Quiet area? Increase. Low crime rate area? Increase. And anything else you can consider a positive when living somewhere. & #x200B; Side note - food is increasing in price and so are other essential things, such as fuel for your car. Making your average job worth less and less because it doesn't pay enough to keep up with the price of everything else. Ask your parents (or someone who is at least 15-20 years older than you) how much they paid for certain things and you'll see that stuff has increased in price. By the way. I use to go to my local milkbar (corner store.. convenience store.) and spend around 2 dollars and walk out with an assortment of lollies and still have change. The same amount today would barely get me a single lolly. | 8 |
czy4ho | Chemistry | how can CO2 stay locked in a liquid and make a fizzy drink, but if you blow bubbles with a straw it doesn't? Not sure if chemistry or physics.. | I don't actually remember very well, but I'm quite sure that for CO2 to be incorporated in a liquid it's necessary to use a certain amount of pressure that you can't create with just your lungs | 2 |
89w5du | Biology | Why are chocolate stains so hard to get out while other stains aren't? | Part of it is that chocolate is super dark, of course. It's also ground very fine too make, so it gets everywhere. And the bits that are not tiny teeny chocolate powder are brown cacao oil. So you've got those three things (each of them a hard stain alone) to make the perfect storm of stains. | 1 |
6pila1 | Culture | Why didn't America start off using the metric system? I get that it would take too much effort to change it now and it probably wont happen anytime soon, but why didn't we start out with it. Why did we pull numbers out of thin air (or how ever they made the current system) instead of using metric at the time? | It was actually introduced (by France) after the USA was founded. France introduced the whole system in 1799, America was founded in 1776. Parts of it have been around for much longer, but the system as whole was not introduced until after we were founded. | 4 |
9zvhwl | Engineering | How do molded dice with depressed dimples (where 6 dimples takes out greater mass on a side than one dimple) get balanced so that they are completely unweighted? | There are dice out there that are engineered specifically to avoid this issue. They're typically casino dice, but the pips (the dots or dimples on dice) on casino dice are filled with a different color to keep them balanced. The general consensus on this issue is that imperfectly weighted dice are *random enough* for most purposes. Meaning that unless you measure each individual die and test it enough to determine which number it will land on the most, it doesn't matter. Most people don't use dice for anything remotely serious, so the general outcome of the rolls isn't that important. Edit: I get it, we all take board games seriously, but when I say important, I mean that most people don't have thousands of dollars riding on their dice. | 11 |
ikxohy | Other | Why is there a minimum age (35 y.o.) to run for US president, but not a maximum age? | A lot of choices in who gets to vote and what kind of representatives you get stem from an underlying left-right ideological divide. Younger people tend to be more left wing, older people tend to drift to the right. The people who wrote the constitution were conservatives who wanted a conservative government. They were literally debating over a king so an older president was a decent compromise. A maximum age for president would unavoidably move the USA to the left. Same for mandatory voting, countries that require everyone to vote tend to be more left wing. Same for 2 party vs multi party. 2 party tends to be more right wing. Not always, but it trends that way. If you want to implement something that changes who can be president, it says something about where you are on the political spectrum. I for one would prefer a toddler as president over the thing we have now. | 10 |
9ntukk | Biology | How does exercise reduces stress if exercise is stressful to your body? I feel we should be using a term other than "stress" because there is lack of information. | You're mentioning two different kinds of stress. The feeling of stress is our "fight or flight" response. Our ancestors developed this response to get rid of or run away from what is causing stress (like a sabertooth tiger chasing us) so we can stay alive. However, our stress nowadays usually comes from more abstract things. Am I what I wanted to be? Am I making enough money? What do people think of me? All these stressors activate our sense of fight or flight but this response often does not fit the situation. Except in certain sports, you can't fight others to get more money and running away from problems means they usually become worse. The other type of stress is physical stress. This is studied in material science and mechanical engineering. It measures how much bending/stretching/twisting something can take before it loses its shape, becomes damaged, or breaks. Our bodies are physically stressed when we exercise. Muscle cells get small tears with use but our bodies will repair them to be stronger. The feeling of stress and physical stress on our muscles are tied together. When we feel the fight or flight response, our bodies go into a high alert state. By using our muscles during this state, the physical stress will cause some tears to our muscles. This action releases endorphins, chemicals that make us feel relaxed to cancel out our alerted state. Combined, our bodies are essentially telling us "Do something physical to escape! Once you do so, you'll feel better!" That is why when we are feeling stressed, physical stressing of our bodies can make us feel more relaxed. | 11 |
esa0ir | Other | Why does it feel like that a word has lost all it’s meaning when we say it repeatedly in a short span of time? | It's called semantic satiation. Basically to do with how the brain processes words and how certain parts of the brain/neurons firing tire out if words are repeated too much in a short space of time. | 1 |
6oobuf | Biology | Why is the sand in the Sahara desert not like regular soil, and where does it come from? | Think about what "regular soil" is. It's a mix of organic material (living and dead plant matter and animals), tiny inorganic particles (clay and silt), very small inorganic particles (sand), and larger inorganic particles (gravel and rocks). The whole mixture is held together by water and roots. What makes a desert a desert? Lack of water. So what happens when you take away the water from normal dirt? First of all, the plants go away. They stop replenishing the organic matter, which also goes away....it either decomposes into carbon dioxide or is blown away. Because the roots are no longer holding the soil together and the soil is to dry to clump, not only does the organic material leave, the silts and clays are blown away as well. These dustlike particles can stay in the atmosphere for a long time...dust from Africa helps fertilize the Amazon, for instance. Wind can blow sand too, but not as far. Sand is heavier and falls out quickly when the wind slows. So the sand particles build up into dunes where the wind conditions are right. What's left behind is the hard, gravelly rock stuthulhu mentions. It's all the bits that are too big to blow away. | 3 |
adydi6 | Technology | How does 'Incognito Mode' work for Google Chrome? | It's doesn't save anything on your computer. No cookies or history. It's only for porn basically. You will not be hidden on the web. | 2 |
8k4bob | Technology | Why do tinted windows almost look like a grid when you wear sunglasses? | Spots on glass are caused by the glass in that spot being under direct contact from a cooling fan and the glass cooling quicker in that spot. Thus altering how the light waves pass through those spots, which is noticeable through polarized glasses. Not related to the tint. This is only the case on tempered automotive glass (anything that isn’t a windshield) due to the manufacturing process. This is why people associate the “spots” or “grid” with tint, since people don’t normally tint windshields and only tint the tempered glass. Source: work for an automotive glass manufacturer. | 4 |
6xlf6t | Culture | Why is suicide so frowned upon? We all die, so why does it matter whether someone dies at 25 by suicide or at 75 by natural causes? | While the arguments people are making here are important, there's also the social and cultural aspect to consider. In the west we have a very Christian view of morality and in traditional Christian views, suicide is sinful because your life belongs to God, not to you. To take your own life is to defy God's plan for your life. Obviously religious dominance on public opinion has waned over the past hundred years, but the effects of it are pretty clear when you compare British and American views on euthanasia to those of European cultures that aren't as Christianity-centric. Other examples of things that culturally come from our socio-religious past are our views on what animals are suitable for eating, fear of the number 13, celebrations of Christmas and Easter (even by nonreligious families), new years resolutions, even football (soccer for Americans out there) fans sing songs to the tune of religious hymns. It takes a long time for those kinds of views to abate and shift. Just look at how long womens rights and gay rights took, and now we're in the fight for trans rights. Culturally we have a Christian heritage and those ideals pervade our society heavily. Almost all common names in the West are religious in origin, even now, and show no strong signs of changing any time soon. I agree that from a secular point of view, the fact suicide is preventable is a major reason for many people, but I think it's a little restrictive not to consider the historical context these ideas and belief systems came from. | 13 |
g16s8n | Economics | In a recession, where does all the 'lost' money go? | It doesn't "go" anywhere, certain things become less valuable. Imagine it is 2017 and you own a fidget spinner store, you might have $100,000 in spinners sitting on your shelves. Then 2018 rolls around and people realize spinners are kind of stupid. They aren't willing to pay nearly as much for them, and suddenly your $100,000 of inventory is worth only $25,000. That money didn't "go" anywhere, people just changed their minds about what it is worth. A recession works the same way, only with stocks, real estate, and loans. | 6 |
6rtb4x | Biology | Why is it that our bodies can't stop producing heat rather then use sweat to cool of excess heat it creates? | To answer this you have to understand that heat,as energy is a product of the chemical reactions going on in your body. In order to keep your cells alive there a millions of reactions taking place inside them, the energy starts out as your food basically. This all produces a net amount of heat that must leave your body to prevent it from getting damaged. Sweat is there to control your body temperature which must be kept constant, if your core temperature drops or rises above normal your cells are unable to survive and start dying due to the stress; their proteins only work at specific temperatures and conditions to keep them alive. ELI5: Your body is like a machine that gets hot when you use it for a long time. It needs to be able to cool down or it might melt and stop working. -Biomed scientist here if you have more questions | 2 |
dbtrtu | Technology | how does the ice machine in the fridge make ice? | A water supply line fills an internal ice mold and when the water has frozen into cubes a mechanism flips out the cubes into the ice bin. If there's an in-door ice dispenser, there is a flapper in the bottom of the bin and an auger to pull ice forward toward the opening when the dispenser is activated. | 1 |
hrhk7x | Biology | How do we know if we are seeing the same colors by name? For instance we both see what we know is “red” but can my red look like your green? | This probably goes a bit beyond "Like I'm 5" so apologies, but you do pose a question that was often asked by an old teacher at my school (I believe it's meant as a philosophical pondering more than anything). Here's two answers to use, hopefully at least one suits your request.... Short answer: Scientists would use the source of the colour, the person or thing seeing the colour, and the stuff happening in between those two, (amongst a bunch of other factors) and conclude that we'd see "x" colour as a result. For example, a butterfly wing has red pigments, the light being shone on it is white, the onlooker has normal eyesight and thus, he/she would see red wings. There's a lot more to it than that but for simplicity sake. However... Long Answer: Basically, there is no evidence to suggest we interpret colours different to one another, but neither can we definitively prove that we see them the same either. What I see as your Red, you may see as my Green, however since we've been taught both our version is "Red" we'd point to the same thing and say it's red and there'd be no way to know if we're seeing exactly the same thing. You could take this as a lesson in perspective, you might both see the same object, but you're seeing it differently and as such, will likely draw different conclusions about the object in question. You could run a comparison with a famous thought experiment about communication with an entity you can't see and who can't see you (often it's an alien on a planet lightyears away). The idea is, since you cannot see each other, or the same things, you need to explain to the entity what is left, and what is right. You can't say "look where the sun is going" because it sees a different sun to you. There's no way to know if it has the same limb arrangement as you so no tricks like "Hold your hand out and see which one makes an 'L' shape with first finger and thumb". You need to explain directions without any reference points, and when you figure that out, work from there and figure out if what you see as Green, I see as Red. | 3 |
junukn | Technology | How does YouTube have enough storage space? | Economies of scale. Google gets to use their own infrastructure, so they can get the cheapest possible storage there is. Really few people actually upload videos that large, and having the small ones stored just once or twice(+ a few times on content delivery network for the currently popular ones) is enough for those hundred million views. Additionally if you notice, youtube uses some pretty heavy compression, even same resolution videos have lots of visual artifacts for detail-heavy videos. | 12 |
gocyck | Biology | - Why certain fish are salt water, others are fresh, and how some are hybrid | I hope that this is at a reasonable level of depth for this sub, I'm recalling from first year bio many years ago: The body has a certain concentration of ions thoroughout in it (charged particles), including in the blood and in cells, this concentration is referred to as osmolarity. These are separated by semi-permeable membranes which freely allow water to pass through, but the ions mostly can't pass without assistance from cellular pumps. If the concentration of ions on one side of the membrane is higher than on the other side, water flows through the membrane via a process called osmosis to try to even the balance. Fresh water has a low concentration of ions compared to the body, saltwater has a high concentration. In freshwater, water the fish is swimming in diffuses into the fish causing it to swell, as a result, freshwater fish pee constantly. In saltwater, the water in the fishes body diffuses out of the fish into the surrounding water to attempt to even the osmolarity. Saltwater fish have to continuously drink to not shrivel up. Each type of fish has special ion pumps in their body to allow these things to happen, which is why they can't swim in the 'wrong type' of water. Fish that can do both have evolved as such specifically. | 1 |
6msg6m | Economics | How have most restaurants maintained high drink prices when McDonalds sells any size of drink for $1? I feel like other companies would need to follow suit to keep up with the competition, yet this hasn’t really happened. | You are having a date at a restaurant. You want a soda while you are in the middle of a meal. Will you get up and walk to the McDonalds a block away to buy a large soda? Competition is a thing but it isn’t just competition for a product, it also involves convenience. | 9 |
7gl4fv | Biology | Why do we tune out smells? It works for both good and bad smells and varies person to person. But I'm talking about you walk into a room with a smell, and gradually over time you start to tune out that smell. For some it takes minutes for others it takes seconds. Which is why your room can smell but since your in it so often you don't smell that smell anymore. So I'm curious... Why do we tune out smells? both good and bad. | Your nose 'smells' things when particles from the object with the scent float into your nose and make contact with various receptors. The receptors they connect with determine if those smells are pleasant, foul, etc. The thing is, this only lasts for a short while until the particles are cleared away and the receptors can reset. If you are exposed to a constant stream of those particles, those receptors become saturated and don't reset. Essentially, it becomes really hard to detect those smells anymore. At least, not until you leave the source for a while. | 2 |
f4mrky | Biology | Why do sounds become muffled or altogether non existent when we yawn? | Yawning contracts a important muscle in the middle ear (tensor tympani) and creates a low rumbling sound. That sound acts as a kind of a counter-force for low frequency sounds coming from the outside and prevents you from registering them. Your brain knows to "filter" most of the sound from yawning since it knows it's being produced by yourself and it's not an important sensation, but the mechanical function in the ear prevents other sounds from working as normal with our hearing. | 1 |
6o3nh5 | Technology | How does AI ever lose at chess? If a human chess player looks x amount of moves in advance to pick their next move, a computer, not bound by memory constraints, could play every combination of every piece on the board; eliminate all games that end in a loss, select only from winning endings and make a move based on that. Then repeat process after every single move. | They don't any more, and possibly never will again. There have been some fairly close matches in the last few years, but overall the best AIs are now substantially better than the best humans. Interest in chess has been mostly replaced by interest in Go, which is itself very close to being 'solved' in the sense that the best humans can't win against the best AI, although not solved in the game theoretic sense. | 4 |