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5uw6md | Biology | Why are certain fruits, such as grapefruit and cranberries, dangerous to eat whilst taking blood thinning medication like Warfarin? | I'm an emergency medicine physician assistant. Warfarin (coumadin) has perhaps the most interactions of drugs with both food and other drugs. Hence people need constant monitoring (blood draws) to make sure they're at therapeutic levels and the drug itself comes in nearly a thousand different tablets. Here is a small list of foods that interact with warfarin. URL_0 | 15 |
711qt1 | Technology | When copying files, why does it always seem to start off really fast, but then slows down so much? When copying files it always looks like it starts off with high speed, but then copying speeds drop dramatically and the graph just looks like a plateau. | There is a limit to how fast you can read and write data on a disk. However to reduce the latency of the disk there is usually different types of caches in the pipeline that can speed up small data transfers. This makes the disk feel faster for regular use but does not help for larger file transfers that is bigger then the caches. | 3 |
kk8b5x | Economics | why do companies like Apple, Microsoft, Sony let their products sell out? I would think that companies this large would be able to handle growing their manufacturing to be able to handle the demand of their flagship products at launch? | > I would think that companies this large would be able to handle growing their manufacturing to be able to handle the demand of their flagship products at launch? You can't run a manufacturing line and its associated logistic chains at more than 100% capacity. You'll need a whole new manufacturing line for that. There is no incentive to ramp up short-term production of goods at such a significant cost if you can just chug along with your existing infrastructure and collect steady profits over the course of months and years. The demand isn't going to suddenly go away. | 6 |
80kydd | Physics | Why do different hose lengths affect water flow So take a large water tank with a tap down the bottom and attach a small hose (say 2 metres) and water flows through the hose no problem. Attach a larger hose (say 10 metres) and no water comes out. How come? | Resistance. The interior of the hose is contacting the water and providing resistance. Flow rate is the difference between the pressure at either ends of the hose divided by the resistance. Resistance is calculated as (8 * viscosity of the liquid * hose length) / (pi * hose radius^4 ) See Poiseuille's law if you're interested. Also, if not on flat ground: gravity. Are you running the hose up hill at all? | 1 |
94kvym | Economics | The Chinese housing bubble and its current status | China has lots of debt from property construction. Many buildings are mostly empty and unprofitable. The government either explicitly or implicitly guarantees most loans. As such, people still find it very easy to get funding for building even if it's clear it won't be profitable. Eventually one of two things will happen: The government will start letting borrowers default and property values to fall The government will go broke paying out on bad debt | 1 |
hap4o8 | Biology | Why is it that some have very visible veins on the hands and some not? What does it mean? | Body fat percentage, genetics and "the pump". I have low body fat, but my veins are not visible all the time, when I'm cold you can't see them, but once I get hot or start exercising then my arms look insane. | 2 |
7rv91d | Economics | What is money laundering, and does business really benefit? I’m watching Ozarks, but having trouble understanding the concept. | The business is a front or part of it is a sham. Like the other poster said it "washed" dirty money -hiding it's origins. The business doesn't benefit but the criminals sure do. | 3 |
9xgc32 | Technology | Why do so many websites feel the need to show a "This site uses cookies" disclaimer message? This seems like a recent web trend that hasn't been around that long. So why are they doing this all of a sudden? What happens when you click agree? And what is the difference between that and just clicking the x on the message? | Some pumpkins decided that because nobody reads or cares about legal notices, the best course of action would be to add yet another legal notice to the pile. | 5 |
icgsfv | Physics | Why does sunlight beaming down through clouds spread out, instead of coming down straight? My mind's logic is that since the sun is SO far away, the light coming to the earth should be in a straight line coming through the clouds as well. But any google image search for "sunlight through clouds" show the lights coming out of the clouds wide almost in a fan-like shape (as if the sun is right behind the clouds). Why is this? | It’s [one-point perspective]( URL_0 ), like a pair of railroad tracks that appear to converge at the horizon. The light rays are parallel, but you’re standing in a different location relative to each one. | 1 |
ayzcoq | Economics | What does it mean to "break up" a big tech company like Google (or any big company) ? If Google suddenly became three constituent companies, what would change? | There are many parts to this. Here's a couple of thoughts: * The separated parts wouldn't have access to data collected by the others. This improves privacy because no single company has such a complete dossier on you as a user. * Each part individually can't so much influence the market in anticompetitive/anticonsumer ways. | 2 |
9okjl4 | Physics | What would happen if a massive planet came very close to earth, as in, would our gravity change? Also, if we jumped, while on earth, would we be in the air longer because the other planet also had gravity pulling us up? | The planets would disrupt each others orbit, draw each other closer together and then shoot apart again, over and over and over like this for years as gravity ripped chunks off of each with every pass, each time getting closer together. Those chunks would hit both planets turning them into lifeless balls of molten rock before finally slamming together completely, most of which would eventually cool down forming a solid mass, a new planet. The remainder of the materials would orbit around the new planet for a while, most of it raining down in the form of giant meteors, until they too eventually merge together and form a moon. That's actually how Earth and the Moon were formed. | 2 |
b0vj7l | Biology | if cold viruses are changing constantly then what is cold medicine actually doing? | Treating the symptoms. The cold virus may change, but treating a stuffy nose and headaches doesn’t. | 2 |
5onhm1 | Culture | Why is Judaism considered as a race of people AND a religion while hundreds of other regions do not have a race of people associated with them? Jewish people have distinguishable physical features, stereotypes, etc to them but many other regions have no such thing. For example there's not really a 'race' of catholic people. This question may also apply to other religions such as Islam. | Jewishness is not a race. People of any race can be Jewish- either by birth or by conversion. Jewishness can be considered an ethnicity (e.g. Ashkenazi, Sephardic, Mizrahi, Ethiopian Jews are ethnic groups). | 40 |
b7qhct | Mathematics | How did NASA calculate that you only need 40 digits of Pi to calculate the circumference of the observable universe? (As per this post: [ URL_1 ]( URL_0 )) Also added math, but might be physics, I have no clue which one would be more specific. | The diameter of the observable universe is about 8.8\*10^26 meters. To calculate the circumference we multiply pi\*d. If our estimation of pi is off by 10^(-27), the calculation will be (pi ± 10^(-27))\*d = pi\*d ± d\*10^(-27). Since d\*10^-27 is less than 1, this is off from the true circumference by less than 1 meter. However, if we were off by 10^-26 we would no longer have this guarantee, since the circumference would be off by d\*10^(-26) > 1. If we want to be even more precise and use hydrogen atoms instead of meters as a unit of measurement, we find that the diameter of a hydrogen atom is about 1.11\*10^-10 meters, and the diameter of the observable universe (measured in hydrogen atoms) is (8.8\*10^(26))/(1.11\*10^(-10)), which is about 8.3\*10^(36) hydrogen atom diameters. Since this is above 10^36 but below 10^(37), we need 37 digits of precision for the calculation of the circumference to be off by less than a hydrogen atom. I assume that 37 was just rounded up to 40 to make it a nicer number. | 3 |
bxo81m | Biology | Why do our bodies build up a tolerance to some medications but not others? | So first we need to talk about a negative feedback loop. A house thermostat is my go-to example. The furnace makes heat *until* the thermostat senses too much heat and turns it off. That's simple negative feedback. Now a thermostat that can control the AC and heat at the same time can do two directions of negative feedback and can modulate toward a "center" setting. Many parts of the body use a similar system to control things like heart rate, blood presure, body temp, stomach acid, bone growth, and so many more... Now most of the drugs that create tolerances will be messing with one of these systems. Now a drug doing its job may be a bit like a space heater. You and your doctor think the room needs to be warmer, so you take your space heater drug. But now your body is kicking on the AC and fighting your space heater drugs, so you need more of them (and then the body fights more and the cycle gets worse), and that's the crux of where tolerance build-up comes from. Drugs that **don't** create tolerance over time often affect body systems indirectly, are absorbed in unusual ways, or are specifically meant to not affect body systems at all. A good example of the last category is any antibiotic, antifungal, or antiparasite medication. The intent when creating one of those is to find a substance that is toxic to the invader you want to kill and doesn't do anything to the human cells at all. So *you* will never build a tolerance to penicillin because penicillin doesn't normally interact with your cells. (The bacteria-tolerance is another story) Most of these drugs are imperfect and can cause some side effects. You may actually be able to develop tolerance to those side effects if your body has a regulatory system related to them. Some medications don't get absorbed into you at all. Digestive meds are a common one. Simethicone and Pepto don't need to get into your cells or blood to do their work, and there's no system that can build a tolerance to their effects. I hope that's helpful. | 6 |
lovmvc | Biology | How can magnesium deficiency cause anxiety and high Blood pressure? Isn't anxiety psychological? | Everything is chemical. That's why medication works at all... our brains need the right chemical mix to work. Too much or too little of a critical chemical can screw up the balance. | 5 |
bgwt5o | Physics | Explosive degrees? I hear things being likened to 15 tons of TNT! Or seven times bigger than the atomic bomb dropped on Hiroshima. I was curious of there is an explosive "in scale" between these two methods. Or, is it chemistry/physics, where you CAN'T find a more powerful reaction between the two? | The "ton TNT" is often used as an informal unit of energy, both for nuclear bombs and other large energy events: it is equal to 4.2 billion joules. One "Hiroshima atom bomb" is sometimes used as an even more informal unit: this bomb was equal to 15,000 tons TNT, or 63 trillion joules. The largest conventional explosions ([Minor Scale]( URL_1 ) and [Misty Picture]( URL_0 )) have involved the equivalent of 4000 tons of TNT; the smallest nuclear explosions ([Little Feller]( URL_2 )) have involved the nuclear equivalent of 22 tons of TNT. | 2 |
6e8rq6 | Technology | In HBO's Silicon Valley, they mention a "decentralized internet". Isn't the internet already decentralized? What's the difference? | Isn't Etherium meant to be something like this? | 16 |
9zp34u | Biology | Why do humans love symmetry/the golden ratio so much? How did this trait help us to survive in the past? | The ability to find patterns was essential for human development, be it on understanding animal habits or the envioriment around us, therefore liking patterns was a good trait that was passed down the generations since the more patterns you were able to identify the better a hunter or farmer you were allowing for you to have more children that would share the same interest for symetry and so on until today | 11 |
bwoog2 | Culture | Why do so many otherwise great TV shows struggle to end their stories well? What is it about the creative/production process that makes this so difficult? Specifically talking about shows versus movies, and shows that are widely considered to be good throughout many seasons. | Simply put, it's easier to tell a 2 hour story than what amounts to an 80 hour story. With a 2 hour movie you spent 20 minutes introducing your characters, build your story a little and then spend 20 minutes ending it. If you've got 65 hours story building, it would feel very cheap to spend 20 minutes on ending it. In modern times the internet also plays a factor here. With fan communities theorizing your possible endings, a lot of writers feel an obligation to avoid ending things the way fans expect, so if the obvious ending is the best ending, it may not get used. | 2 |
nwfr6j | Other | Why does the other side of the pillow cool down more when you flip it? | Your body is hot 98F. Everything in the room is not hot 72F. When the pillow touches your head it becomes hot. When you flip the pillow it cools down to room temperature. Pillows don’t transfer heat well, meaning half can be hot and half can be cool | 1 |
65xkhw | Technology | How does combining Playstations (or any other computer) into a "cluster" create a supercomputer? | Software developer here, Cluster computing is not the same as grid computing or cloud computing or super computing or mainframe computing. A cluster is a homogeneous local network of nodes, a grid is heterogeneous, a cloud is heterogeneous, distributed, and may even be 3rd party. Distributed computing in common parlance is using 3rd parties to perform your computation - typically by running client software. You see this with SETI@home or Folding@home. Data is divided into batches which are shunted off to a node to be processed until completion, and then the results are combined into a single in-order sequence. Hadoop was a method popularized (and then later entirely abandoned for being too inefficient) by google that used a map/reduce technique for grid and cluster computing. A mainframe is a computer that has substantial hardware resources dedicated to moving data and performs transactional operations on that data. The IBM z13 has thousands of processors inside the cabinet dedicated just to moving data, and nearly any component can be hot swapped by shuffling all data off the component and onto it's replacement. Even the operating system can be upgraded entirely without stopping computation. These systems are used in places where less than 100% uptime or more than 0% error is intolerable. Yes, such software exists and you use it every day. The banking system has been running *the same* mainframe software since the 50s, just imagine how many credit card transactions are in flight on Earth at any given instant in time. It's also why bank accounts take a day to post, because daily account transactions are accumulated and then ran in singly large batches overnight. A super computer is a massive parallel computer. These days they're all cluster computers, but that wasn't always and doesn't have to be the case. Each processor is effectively performing the same operation on a data point in lockstep with each other processor. These machines are only capable of accelerating "embarrassingly parallel" computational problems, and that is a technical term. The most powerful super computer would be more than 99% idle and your Halo or whatever would actually probably play worse than it would on your gaming rig or game console. A big technical challenge is keeping the CPU and the network (the "mesh") saturated with data. Efficiency is the whole point to building any of these massive systems in the first place, and you can only compute certain types of problems and the system is only as fast as the slowest component. | 3 |
9tca2y | Other | Why are watches worn on the non-dominant hand? | I wore mine on my dominant side for years and got sick of people asking what's wrong with me. I told people I liked having my watch where I was already looking while writing, but who does that anymore? Now it doesn't matter as much so I switched just to shut people up. | 7 |
cif2w4 | Chemistry | When we listen to a song for the very first time. Some of them sounds wicked and eventually you get sick of it in no time. But some of them are not great at first, but it will grow on you and you enjoy them for longer periods? | No idea if that is it, but here's an hypothesis among others. When we listen to a song we listen to different sectors of it. I guess most people focus on the singer first. Then bass/guitar, then drums. If you listen a song with a bad ass singer you like it instantly, as long as the melody echoes within you. After a few listen you know the lines and know what to expect so your brain scans further and listen to the other instruments. And while not being necessarily bad, they don't kick ass like the voice and maybe you lose interest because it's not complexe enough in relations to your tastes. By complexe I don't mean hard to play or technical, just well written enough to entertain your brain. Now take a song with OK voice track. Down the line you scan further and realise that's not it. The guitar is actually pretty sick. Deeper and you catch the bass and your realize there's a subtle harmonic note here you had not heard. Oh, and the drum, that moment before the last voice line hits hard in the feels and you had not heard it first time. That's my personal take on it. I think we can't catch everything and some of them just unveil their secret along the way and our brain likes that, it's entertaining in the long term. I also think mood and personal emotions have a huge impact. Events of your life can taint a music for life. I still think of my first teenage love when I listen to the song we liked. I still remember my trip to London when I listen to the right playlist. Both nice examples, but you can taint a music with sad and bad moments too. Though it's out of scope of what you asked. But, isn't it interesting? I'd love to read down there what people know of that more scientifically speaking. | 2 |
dl9jx5 | Physics | How is an exposed reactor core in a nuclear meltdown situation contained and cleaned up? | The Chernobyl sarcophagus was built quickly, and without regard to the long-term. Containing the catastrophy was paramount and there was little time to spare. Workers immediately went to the roof and began shoveling debris into the core in an attempt to extinguish it, and aircraft came overhead to dump clay and sand into it. Then, liquid nitrogen was pumped under the core in an attempt to cool it via a tunnel. It was covered with concrete, over the course of seven months, and it was not done safely: 31 died of acute radiation poisoning. Recently, a new concrete sarcophagus was built over the old one it was built hastily and flawed. It was close to collapse and was itself radioactive, and the new sarcophagus is designed to last about 100 years. Fukushima's cleanup is still ongoing, but workers are either working in short increments in protective suits (the suits can't protect after some period of time) or using robots to do it. It's a pretty multifaceted subject, so if you're curious about something specific I can probably dig it up for you. | 3 |
bi0mam | Other | How effective is barbed wire / razor wire as a defensive measure in combat? I feel like in movies all they do just make two snips and continue on. | Incidentally, the looped circular wire common in the US Army is concertina wire, not razor wire. It will still hurt and will snag horribly on everything you’re wearing, but won’t cut you to ribbons just for touching it like razor wire would. This also makes it safer for the soldiers deploying it. As mentioned elsewhere, the wire would slow a ground force and be pre-targeted by artillery or machine gun fire so that clearing the obstacle becomes a very dangerous activity. 3 strands of concertina stacked in a little pyramid take time and care to get through on foot. 11 strands laid side by side are enough to render most tracked vehicles immobile until someone cuts the wire out from around the drivetrain (a most unpleasant task). | 9 |
kk04wk | Physics | What happens if you move towards a photon that is coming your direction? | It turns out what you have been taught at school about adding velocities was a lie. You can't simply say 10 mph + 10 mph = 20 mph. It is in fact close enough to the truth that the difference is too small to matter but if you try the same with higher velocities the difference between the simple addition and reality gets bigger and bigger. In fact there are no two velocities that you could add together to get more than the speed of light and if you want to add two velocities together to get the speed of light one velocity already has to be the speed of light. The way speed works is really very different from how we normally think of it and it can be hard to wrap your head around the implications even if you have the equations in front of you because it is all so counterintuitive. if you look at the light emitted from a moving object all sorts of weird things about it will change. Things like red/blue shift. What won't change is the speed of light. This is because "speed of light" is really a bit of a misnomer, it is just the speed at which the universe happens. Anything that goes as fast as it is possible to go, goes at that speed including such things as gravity. Light is just the most "visible" example. Thinking about the speed of light in the terms of everyday understanding of speed, is a bit like trying to apply your normal understanding of concepts like "going north" when you are at the north-pole. | 2 |
cjbgfm | Physics | Why does the key of a song playing on a set earphones change when the earphones are at some distance from the ears? I was listening to a playlist on my earphones and after a while I dropped them not too far from my ears. I could still hear them but it sounded like the key had changed. Same thing happened when I put them back on, key returned to normal. Whats the cause of this? | it doesnt change the frequency of anything but it would dampen the higher ones which might for some reason make you hear it differently? key is for sure going to be the same though | 2 |
j5hd4p | Physics | If the universe is finite, does that mean that it has some kind of an edge? If yes, what happens if we "theoretically" cross that edge? | Suppose you're Eratosthenes of Cyrenaica. It's 180 BC, and you've estimated the Earth's diameter and done a pretty good job given you were working with wooden stakes and bits of mangy leather. You're extremely well traveled for the time, having been from Libya to Athens and back, some 1500 miles round trip. You know that this means you've only been 1/30 of the way around the globe, more or less. No one has ever heard of what's, say, a third of the way around to the West. There are ridiculous stories about people and animals halfway 'round to the East that just serve to make it clear that nobody's gone close to that far in real life. If you're that guy, you know there's not an "edge" or an "end" of the Earth. You know it's probably not meaningfully different in the Great Unknown; it's just more Earth that cannot be observed at this time. Same thing with the universe, except we can't observe 100% of the universe, even in theory. You get the term "observable universe" to mean there are bits that cannot be known. Like, whatever is (or, arguably, is not) beyond the event horizon of a black hole. And, since we rely on light (and radio waves, and microwaves, etc.) to observe everything beyond low Earth orbit, we can only observe things that have shone light in our direction at some time in the past. So, like our ancient philosopher buddy, there's definitely a limit to what we've seen, but that's not the same as there being an edge to the world--or the universe! It's a matter of little argument among cosmologists regarding what's beyond the limits of observation. I say little argument because they all feel that, as scientists, their business is to deal only with what can be observed. And that's justifiable because every so often, someone invents a better tool or technique and our ability to observe increases and what do we find? Just like Eratosthenes, we just keep finding more universe! EDIT: Added a dropped | 6 |
kyr6zd | Physics | Why do mirrors reverse left and right but not up and down? | None of these is correct. The Answer is that mirrors invert things on the Z-axis, not X or Y. That is, they reverse things forwards and backwards. They *invert* rather than "flip." Here's an excellent explanation. URL_0 | 4 |
au0o7x | Other | What is Solipsism? I stumbled somehow across the r/solipsism subreddit and saw the content though I’m not quite entirely sure what it means. Could someone explain it to me? | Basically it is the philosophy that the only thing you can be certain of is your own existence. You can't rule out, 100%, the possibility that the entire world you experience, including all other people, isn't a dream, simulation, hallucination, or creation of some malicious demon. But, given that you can think, at least you must exist since if you did not exist you would not be able to think, leading to the famous phrase: I think, therefore I am. | 2 |
e6aywx | Economics | How do dividends work in a small company? Having watched shark tank, I’m curious how dividends work in small companies. I know the show is nothing like reality, it was just the basis for this question. If I have a company I had two different early investors- one who has a 10% share and one who has a 15% share, who determines when dividends can be drawn? If my company gets to a point where it’s earning enough revenue to net 100k profit after reinvesting for growth, what’s to stop me from issuing myself a 100k salary instead of receiving profit in terms of dividends? | A lot of times, nothing. You need to be very careful being a minority investor in a small company. Read the shareholder agreement carefully. Small companies are very hard to valuate, and it's hard or impossible to sell your shares. | 3 |
l5exmf | Other | If red tide causes bad shellfish, aren't all the fish impacted as well? And how does the local wild life not get sick or die after digesting, while humans do? | Red tides can cause massive wildlife die offs. Fish and birds are more mobile than shellfish and may try to avoid the area, but a significant algae bloom will wipe out a lot of local wildlife. There’s often a fish die off during a red tide, and then a secondary hit to birds and beach scavengers that try to eat the contaminated fish. | 2 |
dn9ms8 | Other | What is gerrymandering? | Imagine a country where 60 percent of the people vote yellow and 40 percent vote purple. There are supposed to be ten voting districts, with 100 people in each. I like purple, so I draw the districts so that all the purple voters are evenly divided between just six districts; those districts now vote purple (66 purples to 34 yellows). Now, even though purples are the minority, purple wins, because purple controls the most districts. | 3 |
gkem7i | Physics | - If you were in space and had a space suit over your entire body except for your hand, what would it do to you? | Interesting thing, NASA has developed essentially a spandex space suit, not airtight but allows compression so you can breathe and keeps pressure on the skin. This theoretically works just fine, as your skin provides a decent amount of protection. It's been tested, but shelves. It had a normal space helmet, and needed to fit exactly or you would get big blood blisters where it didn't. | 3 |
9b3ac7 | Chemistry | Why does having chalk increase your grip while on something like monkey bars? & #x200B; | Chalk is typically made of magnesium carbonate which serves the purpose of keeping your hands dry. The reason it works isn't that it directly improves grip per se, it's that it prevents grip from degrading in the face of moisture. For most uses that moisture comes from your sweat, but in rock climbing you often encounter moisture from rocks as well. | 1 |
j8t0bw | Physics | Particle spin What in the heck does it mean for a particle to have a spin of 1/2, or any other value for that matter? I keep reading that it isn't just the direction they are spinning, but I can't wrap my head around the concept. | It's called spin because mathematically it's analogous to angular momentum in non-quantum objects. But in the quantum realm, you can't say what's "spinning" or even what spin is. It's just a property of quantum objects, like mass and charge, but there's no sense in picturing a rotating classical object and scaling that down. The analogy falls apart before you reach quantum scales. | 1 |
gbiqee | Biology | What's a 'Dopamine Detox' and does it work? | "Dopamine detox" is a pseudoscience fad: [ URL_0 ]( URL_0 ) Basically, the original idea was just to practice mindfulness and reduce anxiety, but it was misappropriated and twisted by people who don't know much about the brain. Dopamine is a chemical your brain releases when you do certain activities that make you feel good. Other parts of your brain detect that chemical and it trains your memory to enjoy doing that activity, like if your parents give you some money after you mow the lawn. The (false) premise of a "dopamine detox" is that, if you do activities that produce a lot of dopamine, it will cause your brain to demand more and more dopamine to stay satisfied, and the claim is that you can deprive yourself of dopamine-producing activities for a short period of time to reduce your brain's demand for dopamine. The fad attempts to compare dopamine to drug addiction, which is false. Chemical addiction physically changes the brain such that normal function is impossible without the addicting substance. But your brain produces dopamine whether you're being stimulated or not. Doing dopamine-producing activities *doesn't* increase your brain's demand for dopamine, it just makes your memory associate those dopamine-producing activities with being rewarding. Over time you can "forget" about those activities, but not by avoiding them for just a day or two. It's a bit like forgetting about a hobby. If you're playing a video game you really like, you'll want to keep playing it. If you quit playing it for one day, you're still going to want to play it the next day. If you quit playing it for two years, you'll probably forget about it. In summary, a dopamine "detox" or "fast" does not work. Making long-term lifestyle changes does work. | 7 |
gnjhvj | Physics | - Do Electrons in every atom moves at all? If so where do they get their energy? | No. Most of the time the wavefunction of an electron in an atom is completely stationary and does not evolve with time. The other answers in this thread talk about the electron as a point moving around in a cloud, but this is a misconception, the electron *is* the wavefunction, there isn't a little thing zipping around in there. The electron wavefunction can evolve with time during interactions, but in general has a static solution in an atom. | 1 |
723nra | Repost | Why do your legs fall asleep when you sit on the toilet for a long time but not when you sit in a regular chair? Edit: Thank you for all the advice on why it takes me so long to shit. My problem, however, is getting distracted by my phone and just sitting there after the business is done thus causing tingling legs. Guess that's more of a personal problem though. I could have googled but thought of y'all instead- take that how you want. (: Edit 2- I'm strangely proud that a question about the shitter has been my most viral post. | Doc here, I know it's late but here's an actual explanation: The feeling that you get is due to what we call neuropraxia, which is the mildest form of nerve injury. When you sit on a regular chair, your weight is distributed primarily on your ischial tuberosity(i.e. "sit bones") and other soft tissue meant for weight-bearing. When you sit on a toilet seat, the weight shifts to where it's putting your weight onto your sciatic nerves(the major nerve in your leg). This compression of the nerve causes this mild, reversible nerve injury and is responsible for the "falling asleep" feeling you experience. | 18 |
6zlcyy | Culture | Why is handwriting from the past so much prettier than writing now? I was watching a documentary about Newton and his notebook was filled with dense, perfectly flowing handwriting. Meanwhile, my notebooks look like shit. | There's an element of selection bias at play here as well. Documents that survive from older times are usually more durable, because it was important that the information be preserved. This indicates a level of care and concern about permanence and legibility. Shopping lists don't get the same attention. | 6 |
d1x5q5 | Culture | why did western occupations of countries such as Germany and Japan succeed in establishing stable governments, while many attempts at this in Latin America and the Middle East Gail? | Occupation of Germany and Japan followed the WWII and it was an agreement of the peace treaty. Occupation in other parts of the world was due to colonisation. In one case the old gouvernement agree —in some part—, in the other, it is without the will of the occupied. | 3 |
9xw1kc | Other | What exactly are the potential consequences of spanking that researchers/pediatricians are warning us about? Why is getting spanked even once considered too much, and how does it affect development? | Damage to a child’s psychological and nervous system largely doesn’t happen in the singular moment of violence. The damage happens in every single moment afterwards when they are bracing themselves for it, fearing it happening again, modulating their behaviour in expectation for it, and developing unhealthy perceptions/fears/mistrust in their caregivers - even if the next blow may never come. This is why “even once” is irrelevant to how much harm it causes. | 21 |
90dnjc | Technology | How data is transferred between different towers and my cellphone when I’m playing game and constantly changing my position (like riding in a vehicle)? | Each tower advertises their identification, has a synchronisation routine and is able to communicate with your device (UE) to establish how much signal is getting between you and the tower. This allows them communicate with each other to see if another tower is a better candidate for you. Secondary (I'll keep this to 4G technologies only) each tower (eNodeB) has a connection (X2) to near by towers. This allows one to take over if your signal with one beats the other for a period of time -- you don't want to be on the edge of a cell and bounce back and forth between towers. Eventually if you go far enough then you'll do a much larger handover. Towers talk to telecommunications routers (SGWs) and these are also all interlinked so they can hand over to each other. It's a much slower process so this is why traveling on a high speed trains can have more issues related to communications. You may travel even further and hand over between your gateway (PGW) but luckily these are all interconnected with a technology called GTP (GPRS Tunneling Protocol) -- the idea is that your data goes from A to B without knowing or caring how it gets there so you just need to update the routes. You may even need to hand over between the controller (MME) which incidentally is what controls when every other device hands over. Again these are also all interconnected. Fortunately there's a database of who you are, your identity and where you are called a HSS. This helps the network know where you are at all times and provide you a service. This is a tiny subset of the problem and doesn't cover things like. If I go somewhere new and my phone is off, how can I receive phone calls if I move and turn it on again? Source: I build telecommunications equipment. | 1 |
8dbmzi | Chemistry | What is in Almond Milk that causes it to go bad after 7-10 days? | The same reason milk does. Bacteria and fungi eat the sugars and fats in it and once they build up to a certain level it is spoiled. | 1 |
iw1geq | Other | As a country which is so vocal about free speech, why is it acceptable for public libraries to ban books in the US. | TLDR: Libraries are private organizations and can ban whatever they want, and do so because of pressure from patrons. First of all Freedom of Speech doesn't mean that you can say whatever you want without consequences. Freedom of Speech means that the government can't pass laws that prevent you from speaking or expressing your opinion. Government censorship is therefore unconstitutional, but private censorship is perfectly fine. The catch is radio stations, libraries, TV stations, movie studios, etc are private organizations and can self-censor without violating the 1st amendment. It's when the Government does it that it's a problem. The supreme court has had to rule numerous times on what is considered protected speech and what isn't. Movies for example are censored by a private organization (mostly the MPAA) and movie studios comply to the MPAA willingly. There's no reason they couldn't ignore the MPAA if they chose, but lobbying pressure from the organization and threats to prevent movies from being shown in theaters forces their ratings to appear on movies. Libraries are similar, it's mostly lobbying form patrons and the fear of bad press that makes them remove certain books from the shelves. Speaking again about the 1st amendment; Just because you have a right to say whatever you want, doesn't mean that anyone else has to listen to or agree with you. Freedom of Speech can't be used to encroach on other peoples Rights like the Right to Life and Liberty and Pursuit of Happiness. That's why discrimination is illegal and you can't claim your Free Speech Rights allow you to discriminate against people. You can express your discriminatory opinion in public, but you can't enforce it. That being said the US is still a *Nanny State*. Laws are passed all the time to prevent people from doing things because they are unsafe. | 1 |
6ct495 | Culture | why is a signature the preferred method of confirmation? when/why did writing your name become an acceptable form of confirming whatever you were signing too. why not a thumbprint or a picture or some other easily reproduced method? | It wasn't always a signature, signet rings had been in heavy use before as have seals, stamps, etc. However for most individuals, signatures are more convenient and do not require any technology or expansive materials. Thumbprints, picture scanning, etc. are all reliant on relatively new technology and may well supersede signatures in the future, however we aren't there yet. Also keep in mind that for many things a simple signature doesn't suffice, very often you need a government issued ID as well. | 2 |
hulx9o | Technology | Why do some countries on maps appear much smaller/bigger than they truly are? | The earth is a sphere, and maps are flat. That means that you can't draw the curved surface of the earth on a flat map without something getting distorted. There are various maps that preserve various properties - angles, distances and so on, but you never can have a projection that preserves everything. So, on most maps some countries look bigger than they are and others smaller. There is a special map projection called the equal area projection, which does preserve the relative size of countries.but that comes with the disadvantage that it distorts their shape and angles in general. | 2 |
da3mqa | Physics | Why do you feel pressure when picking up speed but not when you have settled into a constant speed while driving? | The pressure you feel is because of accelleration, not because of speed. From Newton's Laws, F=ma. Because m (your mass) is constant, Force is proportional to accelleration. And pressure is just Force per surface area, where the surface area is your back against the seat. So, when you accellerate, you feel the force of your car accellerating you as pressure against your back. Since accelleration is the change in speed over time, driving at a constant speed means no accelleration, which means no force, which means no pressure. | 2 |
a4uvt7 | Physics | Why can't we feel the earth's rotation? I was listening to an interview, from a youtuber I always watch, to a "Flat-Earther" and I was wondering that because it was one of his arguments. | The speed is constant. Like when in a moving vehicle you only feel the speed when accelerating. | 4 |
8lv8ui | Biology | How does the body actually rest during sleep considering cells always need energy (ATP) to work despite being in ‘rest mode’? I learnt in A+P that cellular respiration happens to produce energy at cellular level. Does this ever stop during sleep? If not what is resting while we sleep? Is it ‘consciousness’? | Cellular respiration happens in all cells all the time. Sleep isn't for the purpose of metabolic energy replenishment. It's, as far as we know, a mostly mental thing that aids in memory consolidation and other brain functions. Yes, your conscious mind shuts down during sleep. Altering your thought pattern does not require shutting down ATP production. | 1 |
nebs9c | Other | Why are humans depicted in paintings from ancient civilizations like different than now? Weren't there artists who could paint realistic paintings? Weren't there artists at that time who could draw humans for what they actually looked like. For instance, look at the paintings of kings from the 17th Century or before. | Also a little bit of painting the beauty goal that everyone was trying to reach at the time and lack of knowledge about anatomy. | 22 |
ghkflk | Biology | What’s the ‘Lump’ in your throat before you start to cry? | Your throat, which starts as a single tube eventually splits into two tubes: one going to your lungs and the other going to your GI tract. When you swallow, the body needs to protect the lungs so that food, spit, or drinks don’t enter the lung tube. To do this, we have a flap called the “epiglottis,” which remains open most of the time and then flaps closed to seal off the lung tube when we swallow. When you cry, or in any stressful situation, your “flight or fight” response kicks in. This response works to increase the amount of oxygen your body gets, so your body will expand all airways. When you swallow you are working agains this response because you are forcing the airway closed. As a result, you will feel how tense your muscles are, which is the “lump in my throat” feeling. Edit: mistake in wording | 3 |
ns34of | Biology | During a panic attack the fight or flight response is activated. Why is it called the "fight or flight" response if it leaves you feeling so weak, scared, short of breath and faint. Surely feeling like this is not very effective if you actually need to fight or flee? | Because your missing one. Its not just fight or flight, its fight, flight or freeze. Think deer in headlights freezing. Also panic attacks are a sign of anxiety issues/disorder and while it's true that is part of our emergency adrenalin reaction, its a sign that its malfunctioning. Perhaps due to trauma or perhaps the stress is chronic long term stress not an immediate threat. | 6 |
ix3ca9 | Physics | What happens to metal that is turned into sparks? | The little pieces of metal does get turned into metal dust. The sparks are due to them being very high temperature from the friction that is created when they are cut. Metal dust is usually much finer then sawdust so a lot of it does get dispersed by the wind. You also tend to remove less metal then wood so there is less metal dust then saw dust. Another big difference is that the metal dust, especially red hot, will easily react with the air and turn to rust. So the metal dust is usually mostly rust particles which are very brittle and dissolves in water. It may be hard to distinguish from regular dirt. | 1 |
jzxd9u | Biology | Why do tress grow fruit? Functionally, how does growing fruit benefit the tree? | Animal eat fruit - > animal walk away from tree - > animal peep seed - > tree has now spread farther than it could on its own | 4 |
abn26r | Biology | Eating before or after working out. Should you eat before exercise or after? And why? | If you are concerned about weight loss, then it really doesn't matter what time you eat. Calories add up the same at any time during the day. However, if you want to perform well during your workout, I would eat before. By feeding your body with carbs and calories, you will give yourself a boost of energy that will lead to a better workout. That being said, don't eat a large steak dinner or anything like that, because then it will slow you down. One myth about fat loss is that you can eat as much as you want after a workout, and it "won't count". Please keep in mind that this is complete bullshit. Calories don't care what time of day it is, or what you are doing. EDIT: A pre-workout meal would be something like a banana, a bowl of Rice Krispies, or anything else that is light and has carbs. For myself, peanut butter gives me energy like nothing else. I will usually have a spoon of peanut butter or a peanut butter wrap before a workout. | 1 |
edum69 | Engineering | Why do some small electronics such as a router have a bulky adapter plug, but a large appliance such as a vacuum cleaner have a regular plug? | Because the router runs on low-voltage DC current and needs an adapter to convert the 120 volt AC current coming out of the wall. The vacuum cleaner is a large appliance and all its components just run on the standard 120 volt AC current. | 4 |
ftbfmd | Other | Is there any reason the front tires on 18 wheelers have the spikes that stick out compared to inset in the rear tires? I know they aren’t spikes but couldn’t remember the term for em. Lol | They are both decoration and practical. Semi trucks have long lug nuts holding the wheels on the hubs. The long lugs in the back are also installed in the front for practical reasons (less parts in inventory, less chances of installing short lugs on the rear, etc). If you don't cover the extra threads that are exposed to the weather, they get filled with dirt, rust, etc. and the lugnuts jam due to the debris on the threads. They used to have plain covers, but truckers want to make their vehicles custom to their personalities, so they buy spinners, chrome, extra lights, etc to make their vehicles unique. | 4 |
9889qe | Other | Why can cleaning products never get that .01% of bacteria? We all here it, "This product kill 99.9 percent of bacteria!" Is this a false or is there a reason for it? | Nothing can ever be truly perfect. Also, they don't want to advertise 100% in case someone tries to take them to court over false claims. I don't think they can, either, (in the USA,) due to laws about advertising truthfully and whatnot. Lastly, there are bacteria in the air, so as soon as you're done cleaning something, it is immediately innoculated by the airborne bacteria. | 3 |
5q2q4z | Culture | How do voter ID laws suppress votes? I understand that the more hoops one has to go through to vote, the fewer people will want to subject themselves to go through the process. But I don't fully understand how voter ID laws suppress minorities specifically, or how they're more suppressive than requiring voters to show up in person at the booths (instead of online voting, for example). EDIT: I'm not trying to get into a political debate here, I'm looking for the pros and cons of both sides. Please don't put answers like "Republicans are trying to suppress minority votes" as the answer, I'm trying to find out *how* this policy suppresses votes. EDIT: Okay....Now I understand what people mean when they say RIP inbox...thank you so much for this kind of response, wish me luck, I'm gonna try and wade through all of this... | I live in Canada and I actually have experience working as a deputy returning officer for a provincial election a couple years ago. When I was working, I required that people had at least one of three things in order for them to vote. a) A voting card, the card had 5 or 6 digit numeric code on it, used for the purposes of identifying the voter. They were mailed out to addresses prior to the election based on census data and other info collected (for example, when you received an ID/Drivers license, you have to provide an address) b) If they didn't have a voter card, they had to fill a one page form so that they could be entered into the system. I would enter this information in to ensure that they didn't vote twice and wouldn't have to deal with this during the next election. c) If they had no form of ID, and no voter form, they also had to fill out a declaration stating that they are who they are, and if they lied about the information provided, they could be charged under the elections act. Voter ID really wasn't that bad. It was the people, primarily older folks who were the pain. They would have no voter card, and did wish to provide any form of ID or sign any form to vote. Eventually when they realized that we were not going to allow them to vote if they did not comply, did they produce their driver's license. In my experience, the DMV in Nova Scotia is normally open until 7pm and getting an ID costs max $15. As well we also took birth certificates, and even registered mail as proof. You don't actually need ID to vote here, but if you do, it makes the process significantly easier. Voter turnout for that election I worked was 59% which was unchanged from the previous eleciton, in comparison, voter turnout in the last Presidential election was 55%. | 40 |
ekdtqe | Biology | Why might you opt for regular vitamin supplements compared to just a multivitamin? I have a multivitamin from costco, but I also have separate b complex vitamins, hair/skin support vitamins, vitamin c pills, and digestive enzyme supplements. If a multivitamin covered everything you wanted, would there be a reason to consider buying your vitamins as a bunch of separate pills? (I do not take both right now, I know the risks associated with over-consuming certain vitamins.) | If you have a severe deficiency in a specific vitamin it may be best to have individual supplements so you get enough of that one without overdoing the others | 2 |
9fmxnn | Biology | How do autoimmune diseases work? What causes the immune system to differ from that of a healthy person? Relatedly, are autoimmune diseases like the opposite of cancer (overactive vs underactive immune systems)? | Your immune system works sort of like combining different lego pieces. Combining these leads to different places they can fit onto. We have a system to try and break down the combinations that don't work or that hurt us, but sometimes that system fails. Frequently in an autoimmune disease you form a combination of lego pieces that attach to your own cells causing your own body to mount an immune response. This is commonly due to genetic factors and an environmental event that occurs. There are also things your immune system wants to attack but that look a lot like your own body, which can confuse your immune system and lead to an autoimmune disease. | 2 |
6onmae | Other | Having seeing that gif of the Amish building a barn, what building codes do they have to adher (ex. smoke detectors, etc.) and do fire departments treat fires differently if they are held to different standards? | Growing up in Ohio, Dad hired local Amish to put up a barn by our house for extra storage. Literally went to school one day, and when I got home the barn had seemingly materialized in the back yard from nothing. I imagine they must have been required to meet some kind of building codes for our neighborhood. | 5 |
dmj2kk | Biology | If sleep runs in 90min cycles, then how does a shorter nap help people? Seems like a 40min nap is all I need sometimes. | It doesn’t, not as much as a full sleep cycle. Just like a small snack of goldfish crackers is not going to replace a meal, but it might take the edge off your hunger for a few hours, and make you feel better temporarily. | 1 |
hcxdra | Biology | While fainting is understandably oftentimes caused by drops of blood pressure, why stimulants like Adderall that sharply increases blood pressure can cause the same phenomenon? | If your blood pressure is too high (and in this case, the Adderall could cause vasoconstriction and increased heart rate leading to high BP) the blood is either not getting enough oxygen to carry to your organs (possibly from an erratic heart rhythm), the blood is not able to get to those organs (possible blockage in the vessels or the vessels are simply too constricted, or other reasons too numerous to list out. One other reason is that fainting could be a mechanism by which our body regulates our BP (and other bodily functions). So if our blood pressure is too high or low, fainting would be a good ctrl+alt+delete way of letting our bodies collect ourselves and restore regular homeostasis (physiological harmony). | 2 |
bl1opx | Culture | How did Cinco de Mayo become so popular in the US when it's not all that significant in Mexico? | The celebration Mexican Independence from Spain actually falls on September sixteenth, the day of "El Grito" ("The Shout"). The fifth of May, "Cinco de Mayo", commemorates the Battle of Puebla, in which Mexico defeated the French forces of Emperor Maxmillian. It's not a national holiday in Mexico, and is officially observed only in the Mexican State of Puebla. In the States, it's become a commercial holiday to promote the sale of Mexican beers and food. | 7 |
debo8x | Biology | if cancer is basically a clump of cells that dont want to die, why/how do things like cigarettes, asbestos, and the literal sun trigger it? | Cancer cells result from mutations that disable the things that keep cell growth in check. Those mutations come from incorrect repairs to cell DNA, and those errors happen more frequently the more repairs take place. Therefore things that cause damage that requires repairs increase the chances of developing cancer, stuff like cigarettes, asbestos, and sun exposure. | 16 |
7ns500 | Repost | The moon’s gravity can visibly affect tides, but not the water in a glass. Why is this? | Same reason there are no tides on a small lake. The gravity change needs a massive 'bowl' for the effect to be noticeable. Tides are just the water sloshing around the world due to the changing pull of gravity. The moon pulls water a little closer to it. 5 feet of tides in an ocean that is thousands of feet deep isn't all that much. Now, the gravity at one end of a pond from the moon is basically the same at the other end because they are so close. Same as in your cup. The moon is 3 inches further away from one end of the cup than the other. Vs 25,000 miles for the earth. TL;dr: Much bigger volume in the ocean and much bigger difference in the distance between one side of the ocean and the other to the moon. | 3 |
i630vl | Biology | why is 12 the magical age for drug store medicine? Every time you read the back of a medicine box the age is always 12 when you are considered an adult. Why is this? | Children have underdeveloped immune systems, at around 11 years old the metabolism of the body begins to change in preparation for/as part of puberty. So children 12 and older have a better way to regulate body temperatures, develop specific immunities, and process toxins, all of which make it so that they are closer to adults and can take medicine differently. | 6 |
61z406 | Physics | The 11 dimensions of the universe. So I would say I understand 1-5 but I actually really don't get the first dimension. Or maybe I do but it seems simplistic. Anyways if someone could break down each one as easily as possible. I really haven't looked much into 6-11(just learned that there were 11 because 4 and 5 took a lot to actually grasp a picture of. Edit: [Haha I know not to watch the tenth dimension video now. A million it's pseudoscience messages. I've never had a post do more than 100ish upvotes. If I'd known 10,000 people were going to judge me based on a question I was curious about while watching the 2D futurama episode stoned. I would have done a bit more prior research and asked the question in a more clear and concise way. ]( URL_0 ) | To break it down rather bluntly, each dimension is basically a variable you wish to add to a point in reference to something. For example, when we're looking at a map, we generally only care about the horizontal and vertical distance from our location to our destination. Going up and down hills isn't really our concern when we're driving. Therefore that's 2 dimensions. Another example would be if you want to study the temperature of your backyard over the course of the year, then time and temperature will be your 2 dimensions. However you if you care about the difference between time, location, height and temperature, then you're looking at 5 dimensions (distance horizontal, vertical, and height from an origin like your back fence post and the ground, the time and the temperature). You're still moving in 3 dimensions in real space, two dimensions on a map, but you care about more than just those things. So, "11 dimensions of our world" isn't really the wrong inquiry but begs the question back "what do you care about?" | 17 |
6iowpi | Repost | How come you can be falling asleep watching TV, then wide awake when you go to bed five minutes later? Edit: Fell asleep a few minutes after posting this. Woke up to 1,200 replies! I'm not going to get much work done today... | I think when you're watching TV, you're typically only passively using your mind. You're just taking in the info. So your brain isn't very active, yet there's something going on to keep it from becoming too distracted. Once you turn it off and try to sleep, your mind is free to wander and actively think about anything. | 15 |
87o2yd | Culture | Who has the authority to rewrite the constitution? | Alterations to the US Constitution occurs in two manners. 1) Congress creates an amendment proposal then approves it by a 2/3rds majority. That amendment then goes the the Legislatures of each and every State and when 3/4ths of them have approved it then it becomes a part of the Constitution. 2) The States can choose to hold a Constitutional Convention, effectively bypassing the federal Congress. If 2/3rd of the States call for a convention then they send representative and draft as many changes as they wish to the constitution. Then they vote on said changes and if 3/4ths of them pass them it becomes a part of the Constitution. Other countries have alterations in different manners. | 4 |
6setru | Culture | How are tattoo artists exempt from law? | There are broad exceptions to copyright that are called Fair Use. Fair use isn't defined by copyright laws but it can be used a defense when the rights holder is suing you. One of the tests of Fair Use is whether the infringement will have a negative impact on the market for the original item. If you were selling bootleg copies of Cinderella on the street then it's pretty easy to see that you are having a negative impact on the market. But, there's no one on Earth who is going to see one of the seven dwarves on your arm and decide that they don't need to watch the movie because of that. | 4 |
mywzux | Engineering | Why does tooth paste come in a tube? and are there any companies that don’t put it in a tube? | There are companies who don't put it in a tube, rather a pressy pumpy thing - well here where I am anyway! | 5 |
e3od1m | Technology | How do the antiplagiarism mechanisms work in uni? | My honest answer is don't plagiarize... I know that's not what you wanted, but copying work in university will potentially get you kicked out, and with that on your record it will be harder to find another university that will accept you. As for exact mechanisms, in my experience it is going to be at the discretion of the instructor to look up any questionable information you have used by putting it through a number of different sites that will automatically flag anything that is too close to someone else's published online/print work. Code is different from what I've seen. Most of the time you can find solutions to assignments on Chegg and instructors know that so they check to see how close your code matches that solution. But if you only include code that you were actually taught how to use in class, and turn what you didn't learn into something similar that you did learn to create the same functionality you should be fine. | 1 |
75ah4w | Biology | Why is it that during the day, deer and similar animals in the same family avoid roads but at night they gather on the roadside by the dozens? Why don’t they just stay where they are during the day? I searched and found a couple posts about why animals only cross the road when you are driving by, but all the answers were “they are always crossing, this is just the only time you see it.” However, this doesn’t explain the obvious difference in the number of animals that gather by the roadside at night as compared to the day even when the roads are just as populated. | They aren't on the move during the day generally. Deer for example are crepuscular. Meaning they typically (always exceptions) bed down during the day and middle of the night. They are up and moving at sun up and sun down. Thus why you see them crossing the roads so much at those times. | 5 |
a06lle | Mathematics | The math behind MD5 and SHA-1 hashing I am doing research on these two hash functions and I am struggling to understand how they convert an input into a "message digest" or "hash value". I've heard of modulo arithmetic and prime number multiplication, but what are their roles in the process of hashing? | Grab yourself a cup of tea(and maybe pen and paper to try some things yourself) As far as I can tell, modular arithmatic and prime number multiplication, while important in cryptography are not used in hashing. More on their use later. I'll start with a rough overview of hashing in general. You cut up the message into chunks of a certain length(like 32 bit in SHA-1), translate them into numbers using the ASCII table and perform all kinds of mathematical operations with it. Extreme simplification incoming: basically, you add all those chunks together(add in the sense of mathematical addition) and that's your digest. Like I said, extreme simplifiaction, but the point is that this process destroys a ton of information so you can't reverse it(partly because there are more possible inputs that outputs, meaning some inputs lead to the same output, that's called hash collision). & #x200B; Now, for the other two things. Modular arithmatic uses the modulo operator. For those that don't know, if you perform a division and only accept whole numbers as a result, you'll likely get some remainder and the modulo operation gives that remainder as aa result(e.g. 13/4 is 3 with a remainder of 1, so 13 mod 4 (programmers use the '%' symbol) equals 1). The reason it is used is that encryption usually involves raising the message to the power of the key, so encrypted = message \^ key. Now since the key is often a **very** large number and the encrypted messge would be even larger. So, to cut down on the size, you use the modulo operator on the result. This has 2 advantages: * the result of x mod y is a number between 0 and p-1 (try some examples yourself to see why that is); bomus points: there is a shortcut, so you don't even have to calculate the huge interim result, but that's another story * you cannot reverse the process and get the key(at least without spending ludicrous amounts of time.) & #x200B; As for prime multiplication: there are several asymetric encryption systems that utilizes a public and a secret private key. The public key is the product of two numbers and the private key is derived from those two numbers with a more complex formula. In order to obtain the private key from the pubic key, you'd need to know the prime factors of the latter. Now if you use two prime numbers for the keys, the public key will only have two factors: the two prime numbers. And finding these two numbers, especially if they're very large, is incredibly difficult. Because the only known way to do so is brute forcing; just trying all possibilies one after another. & #x200B; Finally, since hashing functions don't need to be reversible, those two concepts are irrelevant for hashing. & #x200B; I hope this answers your questions. Feel free to ask more. | 1 |
ac15r0 | Physics | Is there a way to visualize/explain how mass curves spacetime in 3 dimensions? I have heard/seen a million explanations but they all use something 2 dimensional as an example like balls on a taught sheet, how does that work in 3D? | Imagine a cubic mesh of little balls ([graphic]( URL_0 )) connected with little springs. Then inflate a ball in the middle (representing giving it more mass) The springs nearest it have to get shorter to keep the outside of the cube unchanged. This means that as a tiny inchworm walks along the surface of the springs it will notice that as it gets closer to the mass, it seems "attracted" to it because fewer inchworm lengths are needed to move the distance between balls. Alas, you can't make a giant, classroom sized version of this like you can with the rubber sheet 2D representation. That means it's a lot harder for students to interact with that a big demo object they can see and touch. | 1 |
mcctu3 | Economics | Why do companies not purchase debt at debt collector prices and forgive it like Stephen Colbert did every year to massively reduce their tax liabilities? | For the same reason why you can't just donate $1 million and save > = $1 million on your taxes - that's not the way the tax system works, and for good reason. The company/individual would purchase the debt at debt collector prices, and they'd be able to deduct the COST TO THEM for the debt off of their taxable income. It's easier to explain in detail with a person so I'll do that. You have $100,000 in taxable income. You decide to buy up $20,000 in debt at debt collector prices and pay $5000 for that. You would be able to deduct that $5000 from your taxable income, so your new taxable income is $95,000. That's in the 22% federal income tax bracket for married, so in actuality you have saved yourself only 22% of that $5000 in taxes owed, or $1100. So you just paid $5000 to "save" $1100. Disclaimer: I am not a CPA, and do not rely on internet advice from random strangers (non-CPAs or CPAs) for tax advice. See a professional for tax/financial advice. | 2 |
5vqye0 | Technology | How did old games and computers display large numbers? For instance, the NES was 8-bit, and 8-bit integers can only be between 0-255. Yet the score (in say Super Mario Brothers) can be into the hundreds of thousands, something even a 16-bit integer can't handle. Pac-Man also let you score up to over 3 million even though the level counter would break at level 256. | In the same way modern computers do it: by storing large numbers in several consecutive bytes in memory. The only difference is that modern CPUs have instructions to perform arithmetic with large numbers natively. Older CPUs didn't, so we have to perform those operations by running a short software routine. As an example, the Z80 CPU can add/subtract 16-bit numbers. If you need to, for example, add two 32-bit numbers you would start by adding the two low words using the ADD instruction. If the result doesn't fit in 16 bits then a 1-bit flag inside the CPU (called C for "carry") turns on. Next you add the two high words using the ADC instruction, which adds up two values and the C flag. If you have a larger number (56-bit, 64-bit, 4096-bit...) then you just keep adding each pair of words using ADC. Source: I grew up using MSX computers and still use them today. I've done my fair share of programming in Z80 assembler. | 4 |
h85skh | Biology | Why some types of meat are not edible? I am mostly referring to species of birds, snakes and the sort, whose meat I've heard is not edible. Why is that? Isn't it, in the end, the same protein-based muscle tissue? Which takes me also to animals like - I dunno- lions, crocodiles, whales. I'm not saying we should start eating everything we see, I'm just curious if we could/why we couldn't. | Let me introduce you to William buckland who tried to eat every animal in existence. It didn’t do him any harm, but he didn’t like voles much. URL_0 | 6 |
d5a06f | Biology | Why don’t we have a cure for the common cold? What’s make this problem particularly difficult to solve? | Because what we call the common cold is caused by dozens of different virii. We'd have to make a vaccine for each one, they also mutate continously so there are numerous different strains you'd have to make vaccines against that would be useless after the virus mutates. | 4 |
bf4jyb | Engineering | How do fuses blow? Can it be from disuse? I'm curious and stupid. I bought a Sega CD recently, and it has a blown fuse. How could something like this happen? Because it hasn't been used in a few decades? Or did someone plug in the wrong power adapter? | A fuse blow because of to high current that heat it up or it can happen from physical force so it might have happen if it was dropped or handled uncafrully without any other damages to the device. If it just the fuse that have died you can just replace it with another with the same rating and it will work. & #x200B; There are electrical components that age a lot more and can fail in a way that result in a short or other problem. The most common is capacitors that contain liquids that can and do leak. A quick search resulted in this article [ URL_0 ]( URL_0 ) with pictures of the board where you can see discoloration because of leaking capacitors. There is also packs of new capacitors for the Sega CD [ URL_1 ]( URL_1 ) so it is relative common problem. So it might be a good idea to if the fuse fail when you replace it to open it and look on the board for leaks. To replace them you need to know how to solder and there might be a idea to let someone else do the replacement. | 2 |
bzict9 | Other | why are eggs almost universally sold in packs of 12? What made farmers agree to sell this way? | What else would they do with that extra space in the cardboard egg containers? | 3 |
9lpab9 | Technology | Why do computers slow down and take longer to perform even basic functions as they age? My macbook pro is from 2012 and was a high end 13 inch model at the time. I've had one major repair done to it. It has slowed down a lot. Video editing is difficult at best and takes so much longer than it should in general. Even basic emails/chrome use has become slower. I know planned obsolesce is a thing. I haven't updated it past OS Sierra. Do other computer companies do this too? Why does it happen? What is happening? | Your computer isn't a single tasker. It's multitasking. Every program you have running is available to be wanting to do something. So while you may have chrome in foreground, MacOS updater, Adobe Acrobat updater, time machine backup, etcetc are all running in the background. In addition, your cpu is auto controlled to be slower if it's getting hot. If you've not cleaned the internal heatsink, it could be not dissipating heat properly. If addition, parts of your computer do wear out. Hard drive, memory do wear out from usage and heat cycles. That means your computer hardware is technically less capable than it was years ago | 5 |
duhxqo | Culture | what are baby boomers, millennials, x y generation?? | These are members of different "generations". A "Generation" is a time span of about 15-20 years (could be a little longer or a little shorter), where the people who were born during that time have a lot of things in common (like the historical events they lived through, values that they generally share, political views they might have, stuff like that). "Baby Boomers" is the generation that started right after World War 2 (usually put at 1946 - 1964). They are called that because the war ended, the economy was doing really well and men were returning home from being overseas and people were having a lot of kids. "Generation X" came next (usually around 1965 to 1980). Called Generation X because of the math variable X - it was kind of hard to define them. Because people used "Generation X", "Generation Y" followed - that's what is most commonly called the Millenials now. The birth range for this is about 1981 - 1995, but less popular sources extend that to even the early 2000s. Generation Z is the later generation, and now we're living in the time period of the even newest generation. Generation Z will probably get a new name (I've seen 'iGeneration', for instance) with time. Generation naming and identifying is a pretty new thing that only started a few decades ago, and it is not an exact science. | 1 |
juzv7h | Chemistry | Why can hot glass be put under cold soda water to cool it down without shattering, when normal water would make it shatter? | So I've been searching for anything that would confirm your question but I can't find anything that would somehow allow glass to survive what's called "temperature shock" simply by using soda water. Do you have any reference? Glass, most commonly soda glass, is really sensitive rapid changes in temperature. When cold liquid contacts hot glass, the glass closest to the liquid cools and shrinks while the rest of the glass stays still. That causes the glass to shatter. Boro-silicate glass is basically immune to temperature shock, but is more expensive. Like putting nitrogen in your car's tires, boro-silicate glass just doesn't expand as much as regular glass when exposed to high temperature changes so it won't shatter. | 1 |
ctdws2 | Physics | How fighting fire with another fire actually works. I heard that firefighters are using this procedure to deal with great fires. Could somebody explain the aspect of physics behind this phenomenon? | If you perform a controlled burn along a strip of land in front of the fire, then you use up the available fuel and halt its progress. | 4 |
8qnstj | Physics | In space, what opposing force keeps orbiting entities, like planets/satellites, orbiting against the constant pull of gravity? Is the opposing force unlimited (never runs out) like gravity? I understand that lateral motion along the orbit keeps it from "falling in", but how can it go on _forever_ without some force compensating for slowly decreasing speed due to pull of gravity? | There is no opposing force. Orbiting is when something is falling due to gravity, but it continually misses its target. > but how can it go on forever It doesn't because nothing goes on forever. In the context of the universe at large, it's very important to make the distinction between "Forever" and "For an unthinkably long time". > without some force compensating for slowly decreasing speed due to pull of gravity? And why would it slowly decrease? There's no friction in space. There's *nothing* in space. | 2 |
awlax9 | Other | Where did the style of a Cape come from? Did it ever serve any functional purpose, or was it always purely for fashion? | Capes are rainwear. With your hood or hat (everybody also once wore hats) they keep you dry, and allow you to ride a horse while remaining dry. When people didn't ride horses as much, they had a hand free to carry an umbrella. That's why it's called a "little red riding hood". | 4 |
8oc0lo | Biology | What exactly stops us from urinating and defecating in our sleep? | It is a learned behavior. Remember babies are born with them set to go on automatic without waking up. As you grow you learn to take control of the process, and not do it in your sleep. If it the need becomes too urgent when you're sleeping, you train yourself to be awakened by the sensation. | 2 |
hvmj8p | Engineering | How are the giant crucibles that are used to make and move molten steel and iron manufactured? How do they, and the furnaces, not bend and melt? | They use crucibles or refractories typically made of ceramics. Ceramics are clay (extremely finely ground rock) mixed with water and heated. They have melting points higher than most metals. Iron melts at 1375°C; most ceramics melt at over 2000°C. Tungsten melts at 3400°C, the highest of all metals. Tantalum hafnium carbide melts at 4000°C, the highest of any known ceramic. Now, you may be asking yourself, how do we melt *those* without melting their container? The answer is: we don't. Most things with super high melting points don't get melted. Instead, we use powder metallurgy to shape and combine them, which involves very high pressures to squeeze things together. | 1 |
k6i5os | Biology | Why does the brain wake up in the middle of the night with seemingly no reason at all, and then refuses to go back to sleep, despite the fact that you are absolutely exhausted ? | That's what happened before industrial times. It's a natural trait that's less common today, but still in our bodies | 10 |
aqjwrb | Economics | How do seasonal theme parks or water parks stay in business/make money in the off season? | Pretty much the same way seasonal employees survive. You make a lot of money during the season to sustain you for the year, plus their operational expenses really drop during the off season. | 2 |
738ifv | Biology | Why is it that the liver can (to an extent) regenerate but other vital internal organs cannot? | The liver can sort of regenerate, but other organs can regenerate, sort of, as well. All organs will adapt to (non-fatal) damage. Skin heals, bones remodel, the heart hypertrophies, the brain adapts, lung will expand to fill empty pleural space, one kidney can do the job of two, one testicle or ovary will do the job of two. You can survive missing or damaged organs of balance, hearing, smell, taste and sight. It's never as good as the original but there is a lot of resilience in the system. | 17 |
5px7np | Technology | What is Net Neutrality and why is there a lot of controversy surrounding it? | The idea of Net Neutrality is that all internet traffic has equal access to bandwidth/speeds. Doing away with it would be akin to allowing for highway speed limit signs that read "Speed Limit: 65, BMW Owners Speed Limit: 85" if BMW decided to pay for such access as a selling point. Or conversely, it'd be like a state choosing to impose slower speeds against a car maker who jilts them and builds a plant in the neighboring state. On the internet, this could play out with ISPs being able to pick winners and losers by doing something like giving Hulu priority speeds and throttling Netflix, since Comcast owns NBC, which is a partner in Hulu. Or an ISP might speed up load times for right wing news sources while slowing access to left wing sources. The loss of Net Neutrality could mean the uneven flow of information, which goes against the basic beliefs of the internet being open to all. | 5 |
jm5x8g | Economics | Why do companies care about the stock price after the ipo? I understand that going public is a way to secure funding for a company. However, I do not understand why the stock price is relevant for the company once they have gone public. | Companies are owned by the people who own the stock. These shareholders want the stock they own to be worth more in the future. Therefore the people who own the company want the stock price to go up. Additionally, many companies will include some stock options for employees (especially for high up employees) which mean the people actually running the company day-to-day also want the stock price to go up. | 3 |
cepvpx | Biology | Why do you die almost instantly when the level of CO2 in the air is above 10%? | The red blood cells serve the purpose of transporting O2 from the lungs to where it's needed, and transporting waste CO2 from where it's produced to the lungs. The mechanism is simple: It'll grab hold of dissolved oxygen or CO2 if there is much of it, and release it when there's little. Since there's a lot of oxygen and little CO2 in the lungs, it will release bound CO2 and grab oxygen. Now if there's a lot of CO2 in the air, instead of picking up oxygen in the lungs, many red blood cells will pick up CO2. This will massively reduce the amount of O2 you can breathe, which by itself is already dangerous. On top of that, the dissolved CO2 will make the blood acidic, which is dangerous because many functions of the body rely on the pH of the blood to be slightly basic. On top of all that, CO2 is usually not just added to the air, it's produced by burning oxygen. So the 10% CO2 air also has only 10% oxygen, half as much as air normally has. However, you're not going to die almost instantly. You will however quickly pass out and die if you keep breathing that air. | 1 |
5nxvka | Biology | What causes the difference in intelligence between persons? URL_0 sorry if this has been submitted before, I'm new to this sub. | A combination of nature and nurture. Genetics obviously plays a role at the beginning of life. Someone genetically inclined to have higher cognitive functioning can still be a naive moron if raised in such a way. Same with an average Joe who's seen the world and learned how to process information in an efficient way. | 1 |