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8jbsp2 | Chemistry | What are free radicals? And should I be concerned about them from a health stand point? | From a biological standpoint, free radicals are unavoidable, but you have antioxidants in your body that are used to deal with them. You can't really take anything to boost it unless you're planning on IVing vitamin C. Normally, molecules and atoms like to pair up their electrons. This makes them more stable. When atoms have an unpaired electon, this is known as a free radical. It is high energy, short lived, and basically reacts with anything it touches. It can cause cellular and DNA damage. Free radicals are a consequence of using oxygen (respiration) and your white blood cells use free radicals as a way to kill things (it's basically like a shotgun). They can also convert free radicals into useful components called reactive (oxygen) species which act as signalling molecules, and the aforementioned damaging molecules. Your body have mechanisms to deal with them when you're healthy, called antioxidants. However, you can be in a state of oxidative stress when antioxidants are being diminished and you have raised free radicals/oxidants going around. This happens when you're undergoing chronic inflammation (so things like cardiovascular disease and diabetes (and obesity) are going to be the most common ones) You can't build up extra antioxidants, because your body tends to flush it out anyway. There's nothing you can do besides be as healthy as you can possibly be and your body will do its best. | 3 |
5srowe | Repost | How can gorillas and other herbavores get so big and muscular from a diet of essentially leaves and plants, while vegan humans tend to loose muscle mass on plant based diets? | I mean as a vegan my muscle mass has gone up since I became one. I used to be baby fat pepperoni pizza body. Now I only have A little chub and muscle | 19 |
l4ofhb | Chemistry | Why do the walls to a nuclear reactor have to be so thick, if a hazmat suit is fine while you’re inside the chamber itself? | The Hazmat suit is there for a short exposition to radiation, it will protect you enough to be able to not die in the next months after going near something radioactive for a few minutes/hours. The walls are there to allow people who work nearby to pass relatively close to the nuclear reactor on a regular/daily basis and not developing a cancer after 3 years of exposition. | 6 |
gw2imh | Technology | How did they fit open world games like Zelda and the original Final Fantasy into NES cartridges With some basic Googling It looks like that the max size was around 512 KB. How is this even possible to fit games of this size onto such little memory? What is this magic? Edit: Wow, this absolutely blew up. Thank you everyone for the detailed answers. Several people have linked the Morphcat Games video which I will share here. It is very informative. URL_0 Edit 2: I also did some more of my own research and found this video very informative about 8 bit graphics and processing: URL_1 | **Turn back, this way lies madness.** It is all highly optimized code using weird tricks on top of tricks on top of tricks. The kinds of things where one engineer explaining to another might take an hour to show how 5 lines of code does anything, let alone what the first engineer is claiming they are doing with it. | 13 |
eyjyku | Biology | how come one nostril can produce a lot of snot when the other one doesn’t? | Your body actually makes sure one nostril is open when possible so that breathing can continue as normal. There are times when they are both clogged (or both open) obviously, but when there isn't too much to get rid off, your body just picks a random nostril and places all the mucus there so that you don't have to breathe out of your mouth. | 1 |
neakw0 | Biology | what does a shark “feel” from magnetic fields that allows them to navigate by it. I recently read an article about a shark using the Earth’s magnetic field to navigate great distances across the world’s oceans. I’ve always been curious about this. Does the magnetic field give them a physical sensation or tingling in their brain or is it more of driving a subconscious instinct? I guess the same would apply to a bird or a butterfly or any other creature that uses magnetic fields to navigate. | What do you feel when you're sensing light or sound? It would probably be similar for a shark and the magnetic field. It's probably impossible to tell what an animal senses with a sense we don't (really) have. But just by examining our other senses, we can get a glimpse of how senses that we don't have might feel. | 2 |
7odztq | Technology | If lie detectors (polygraph) are a pseudo science the why are they still used in court cases and by law enforcement? | Not used in court. Never talk to police without an attorney. They lie too much. Too often. | 11 |
o8aj2j | Technology | . Why is it that most video games today push you to play online? | To make more money off of you. To be able to have ads, tracking and in game purchases. There’s the other side of making games better with multiplayer and patches and updates to a game. But mostly it’s to make more money. | 5 |
7b6uqp | Chemistry | What makes spreadable butter/cream cheese spreadable? I'm assuming there's some sort of additive that accomplishes this but couldn't think of what it could be. | I think that at least with spreadable butter they add vegetable oil of some kind. Usually canola oil, in my experience. Spreadable cream cheese is usually spreadable because it's whipped, no? Unless there's a similar product to spreadable butter | 2 |
mejya6 | Biology | Why does lighter skin get sunburnt more than darker skin if white reflects sunlight and black absorbs it? Shouldn't darker skin get sunburnt more than lighter skin? | Dark skinned people produce more melanin (pigment) which is very effective at neutralizing harmful UV radiation, reducing the risk of sunburn and skin cancer. | 4 |
9ofkpj | Physics | why is there such a disconnect between our brain's intuitive understanding of physics and our ability to put that into writing? So if someone throws me a ball I can catch it, but if someone gave me the details about the force the ball was thrown with and all other details (gravity/wind/air resistance/etc) I wouldn't be able to calculate where it was going to land, definitely not be able to calculate how to move my hand into the path of it at that exact moment. | There are many animals that are capable of catching a ball, but there's only one animal capable of writing about catching a ball. One problem was solved by evolution millions of years before the other. | 2 |
gxyjai | Economics | Why is the labor theory of value no longer considered correct? | Many other posts in this thread provide good explanations as to why the labor theory of value isn't useful for determining the general value of an object produced by labor. This is almost always what an economist is trying to do, so that explains why modern economic theory doesn't engage with it. The more charitable interpretation of Marx here is that he was making a philosophical/ethical point. A brain surgeon and a Wal-Mart greeter will doubtlessly produce different amounts of value with an hour of labor, but they are still both people of equal dignity, and it's likely that *they* consider their time equally valuable. They both have stuff they'd rather do than work, and working is equally arduous (or close to equally arduous) for both of them.\* Do we, as a society, have a responsibility to ensure that their time is not ill-used? The brain surgeon probably produces enough value that the job is worth his time. What about the Wal-Mart greeter? A market-based solution posits that the greeter's job is worth their time because they were willing to show up for the posted wage (which is in turn related to the value of what they produce as a greeter). Marx might argue that they only showed up because the rules of the game are "come to work or have no money to buy food and shelter." It's just not clear that Marx managed to come up with rules that were better and still ended with most people getting food and shelter. \*Labor economics proper raises direct objections to this claim. Some people like to work more. Some jobs are harder than others. The 10th hour of leisure in a day is less pleasurable than the first. We can set these aside for now. | 8 |
9pk1sf | Culture | The phrase/analogy "You can't have your cake, and eat it" | Common sayings and proverbs don't have to make semantic sense. Ex: "It's raining cats and dogs". In this case though, it does make sense. Think of the 'have' as meaning 'keep' You can't keep your cake, and eat it too. Historically speaking, the proverb existed both with 'have/eat' order, and 'eat/have' order. But the first one become more popular in the last hundred years. | 1 |
62845s | Other | What's the difference between what congress did yesterday to sell your browser history and what yahoo/google/Facebook was already doing? | You can control what you give to those sites. You can't control what you give to your ISP because they are your gateway to the net. | 3 |
9pvp8k | Biology | Why do pigeons and other birds do that head bobbing thing when they walk? | Their eyes can’t focus the way outs can. When they walk, things get kinda blurry. To fix it, they push their head forward, being blurry for a small moment. Then they keep their head still (as in fixed in space, not fixed to their body) as they walk to let their body catch up. When it’s caught up, they do it again. | 4 |
llwoi4 | Mathematics | Converting repeating decimals into fractions | You sneak the repeating part out, by using 10s: * Let's say you're converting 3.7..., so start by saying **x = 3.7...** * If x = 3.7... then **10x = 37.7...**, right? Easy enough so far. * Now subtract: * 10x - x = 37.7... - 3.7... * 9x = 34 * Now solve for x: * x = 34/9 If there's more than 1 repeating digit, just use as many 0s in your 10x. So in the above, we used 3.7... which has a single digit (7) repeating, so we used a single 0 in our 10. If we were solving for 8.43(repeating), with two repeating digits (43), then we would use two zeroes and do 100x instead of 10x: * x = 8.43(repeating) * 100x = 843.43(repeating) * 100x - x = 843.43(repeating) - 8.43(repeating) * 99x = 835 * x = 835/99 | 3 |
m2rskn | Biology | Why are human males designed like video game monsters by having a weak point on the outside of the body, testicles. Why is such a painful and sensitive organ just dangling outside of our bodies instead of protected inside a shell like a brain? | There is also a hypothesis I was taught that basically says sometimes really disadvantageous features become the norm in an organism as a sign of showing off just how successful the organism is as a whole. Basically having testicles in such a vulnerable location forces the male to go above and beyond to care for them, to protect them and keep them free from harm. This demonstrates to potential mates that the male is such a successful creature that it can cope with obvious disadvantages and still survive. | 7 |
lco842 | Economics | How do taxes work? Additionally, why would wealth tax not work? | **Wealth** measures the value of all the assets of worth owned by a person. ie: if I made $5 selling lemonade one weekend, and I also have $100 worth of baseball cards, my wealth is $105. Wealth Tax would tax the $105. Income tax would only tax the $5. | 1 |
eocp4x | Physics | how do volcanoes create so much ash? Like why’s burning down there to create so much ash? Isn’t it just lava? | The explosion is throwing up a fine mist of liquid rock. Because the droplets are tiny, they lose heat fast and solidify. It's the same process we use to make snow on ski resorts, but with rock instead of water. You don't want to breathe it because some of it is tiny shards of volcanic glass, which would give you the same lung problems asbestos does. ~~In addition to that, you do have a bunch of incomplete combusion going on, both of stuff in the lava and of all the dirt/trees/other biomass being incinerated. Our cars would put out a ton of smoke as well if we didn't have catalytic converters completing the combustion, and volcanos definitely don't have those. So instead of the stuff that's burning becoming pure CO2 and water, it becomes all kinds of other nasty stuff.~~ see below | 1 |
n2soxy | Engineering | why can't we have gear ratios like 1:300.000 I've recently seen videos on YouTube showing gear ratios like 30 million to 1 when you spin the first gear super fast at 10.000rpm and the last gear spins so slow it would take 300 hours to spin once for example. Searching for the opposite doesn't give any result, the highest I found was 1:625. Why is that we can have millions:1 gear ratios but not 1:millions? | Two reasons: * If you're increasing the speed something spins, you're decreasing torque (how hard is it turning, or how hard is it to stop). At some point you'd need an insanely powerful motor, just to overcome the friction at the last gear and make it turn. * Even if you had a motor that powerful, you'd need gears that can survive that torque, and gears that can rotate fast enough without breaking from centrifugal force. | 4 |
737h3v | Culture | why do different countries drive on different sides of the road? | URL_0 So that right hands have the advantage. Ancient custom was to walk on the left so you had your dominant arm toward oncoming foot traffic. When cars became the norm, seats moved to the left to accommodate right handed people. driving on the right made more sense. Some countries disagreed. | 2 |
j5vbec | Physics | What is actually happening to an electron inside of an atom? It's not orbiting the nucleus, but its in blobby wave function and its wave function can collapse to a single point of electron. So what is it doing? is it just there or does it move around the atom? | An electron is a wave in the electron field, like a photon is a wave in the photon field, or more commonly called the electromagnetic field. If waves are left free, they propagate. Like light. Or sound. Or ocean waves. Or a beam of electrons. If waves are bound to something, they form standing waves. Most obvious example is a guitar string. It's a mechanical wave bound on either end. As such, when you pluck the string, the wave travels to one end, bounces back, and then overlaps itself. After some time, it forms a nice standing wave you can physically see on the guitar string, [like this]( URL_2 ) Note the wave doesn't even really seem to move, just sits there. [There's nodes where it does not move at all, and antinodes where it moves a lot.]( URL_3 ) The fundamental harmonic, ei the note, is just the entire string vibrating. The first harmonic is a single node in the middle. If you limit the string on the fret, you shorten it and hence change the wavelength (note). The microwaves (light) in your microwave oven does this. This is why it has cold and hot spots in your microwave, the nodes are cold spots. If the spinning plate is jammed, these are really obvious and you'll have boiling food a few centimetres away from frozen food. The walls act as a boundary, just like the ends of a guitar where the string is fixed. It's obviously a little more complex than a guitar string, after all it's not 1D and not physically moving. There's a 3D pattern, and the difference is the strength of the electric and magnetic fields at points within your microwave. Nonetheless, there is still very real and very noticable nodes and antinodes, as the light is forming a standing wave in your microwave. Just like a guitar string. Electrons also form standing waves when they are electronically bound to a much, much heavier positive charge. That is the nucleus of the atom with all the protons. Each orbital is actually a harmonic. They are just different 3D spherical standing waves around the nucleus. > and its wave function can collapse to a single point of electron. So what is it doing? It never does this. We have never isolated an electron to a single point, ever. We have isolated an electron to an incredibly small space, much smaller than an atom, and there seems to be no limit other than our ability to find a better way to confine it within a even smaller limit, but never have we confined it's extents that small. Frankly, we have no clue what would happen if we did, our theories aren't that complete. So what is a wave function collapse then? It's a transition in the wave of the electron. For example, if an electron moves from one orbital around an atom to a different one (that is, changes harmonics), it's waveform changes. Now, if you go and really try to interact and confine the wave, you can make it transition to a really sharp and narrow wave. But still a wave. Consider a nice ocean wave for a second. What's really easy to identify here, the wavelength. All the wave peaks have a really consistent distance between them. It's a really nice and clear wavelength. (for an electron or photon, wavelength is its momentum). But where is the ocean wave? Well, really, you don't know. You can point to any specific peak sure. But why a peak? And why that one, it's the same wave as the next peak 5 down. The wave location is basically undefined, it's everywhere. Well, unless you go way up to scale, then your could say it's in this sea. And at that scale, yes. Now what if we jammed all that energy up into a nice single peak. Like say a tidal wave, a tsunami. Well, then you can definitely point to where it is. It has a really nice defined and tight position. But what is its wavelength? Well, it's really poorly defined. In fact, the correct answer is it has a whole lot of different wavelengths at once. [Here's a nice animation.]( URL_0 ) As you can see, it starts as a nice even wave. It has a clear wavelength, but no real position. When you add more wavelength on top of it (making its wavelength poorly defined), you get a nice sharp peak in one spot. A nice defined position. Now, all of this is true for waves. Any waves. It's called a Fourier transform. When you apply that to the wave of quantum, it's called the Heisenberg uncertainty principle. Basically, the more well defined of position an electron has, the less defined its wavelength (momentum) is. So an electron is wave. It's an excitation in a quantum field. It's bound to the protons, and forms a nice standing wave around them. Each successive electron around the atom takes a new, higher harmonic. When you interacts with an electron, it doesn't magically transform from this spread out wave to a solid particle. It just shifts to a much more well defined position in a tighter wave. You've confined the position more by interacting with it. Now of course, the quantum weirdness is that this is all probability based. Electrons form diffraction patterns, like light or any wave. See a light or laser shined through a small holes, [the diffraction causes this]( URL_1 ) A whole beam of them acts like light, bright spots and dull spots. A single electron has a probability. Its wave spreads out from the diffraction, but when it hits a sensor behind the wave tightens up to a random spot within the wave. Somewhere on the sensor the electron will confine its self. More than likely in a bright spot than dark in a pattern, just like lightn When you pass a whole bunch of electrons through, a beam of them, you would see a nice pattern from the probability that looks just like light shining through a small hole. Most other weird quantum phenomenon can be explained by the fact it is a wave too. Quantum tunneling, is that a particle teleporting through an object? Well, no. It's an evanescent field part of the wave that exists into barrier, if short enough emerges at the other side. Light does the same thing. As does sound. Or any wave. | 3 |
5mwsz3 | Technology | Why are there so many different USB Cable connectors? | Alright, going down the list of the ones that you have probably seen, there are a few more. The most common type you see is USB type A. The thin rectangular one most likely in the side of your computer. This was the original design of USB, however it should be noted that USB was designed with what is known as a master-slave relationship between connected devices, or at least that was what developed. This is where USB type B comes in. The side where USB A is connected is the master device, it is the one that does all the controlling, it does all the commands and charging. It controls the other device. USB type B, the bigger more square one which isn't that common today (more on this later), is the slave device, the device the master controls. This is why USB type A inserts is pretty much exclusively on computers, or at least this was the standard. The main reason this exists is to prevent short circuiting, but since it is the USB type A port generally sending the signals, it became dubbed the master. Now, USB type B was somewhat replaced by USB mini, which is the smaller connector that is jagged on the sides, it was smaller, phones were becoming popular and smaller, a smaller connector was necessary for USB type B connection. It however was somewhat flawed, it apparently was structurally poor, wore down the port too much, so it was redesigned again, to make USB Micro, the common connection on Android phones today, but slowly getting replaced once more by the next port. USB type C is the replacement for pretty much everything on this list. It gets rid of the issues that a same port Master Slave system has, such as short circuiting, is reversible, most likely a trait borrowed from Apple's lightning connector. It is the best USB connector at the moment. But we are not done yet. USB versions, this one is fun. So, versions of USB 1 were practically not used, so we skip that to USB version 2.0. Classic USB port, sadly still very widely used even if newer versions are available. Has 4 pins inside of it, 2 for power delivery (+5 Volts and ground), and 2 connections for data transfer. USB type B has the same pins, while USB mini adds a 5th pin for mode detection, which detects the type of connection on the other side, this one can actually have the other cable be connected to USB B, and this last 5th pin is added as a detector for it, if it is USB type A, it is hotwired to the ground wire, if not, then it isn't connected at all. Now, it is 2008, the 480 Mbps of USB 2.0 is starting to get slow, so our boys at Intel and many other companies get together and make a new version of USB, version 3.0. This changes the type A connector by adding another 5 pins to increase the data rate to a whooping 5 Gbps. Compatibility with USB 2.0 ports is kept by adding these last 5 pins in the back, where they will only be connected if both the port and the cable are USB 3.0, if not, those contacts will never touch, and it reverts to USB 2.0 mode. It is also denoted by having the plastic in the port or connector be a blue color. So, type A was updated, and guess what that means? More wall of text because now we have to update type B ports, including the mini one. Type B maintains its overall shape but gets a weird "roof" to house the last 5 connections for it. [Here is a nice image]( URL_1 ). But this will largely be ignored because type B is being replaced by microUSB, which was also updated... except microUSB 3.0 is also largely ignored because its primary use, phones, did not need the speed until now, and the connector needed an extension to house the extra 5 pins. [So now it looks weird as fuck, because the ports have to maintain compatibility with classic microUSB 2.0, which can be plugged into half of the port, [as shown here]( URL_2 ). Mini USB was abandoned, as it was replaced by MicroUSB. But we are not done yet. Small revisions to USB 3.0 without changing the pinout allowed for USB 3.1 to transfer 10 Gbps, so a small update was made for that. Then, for some weird as fuck reason, they decided to rename normal USB 3.0 as USB 3.1 Gen 1, and the 10 Gbps ports as Gen 2. And now at this point, once again, our boys at Intel, Apple, and several other tech companies gathered around, sat down, took a look at [this clusterfuck]( URL_0 ), took a deep breath, and said things must change. So, they got their asses working on yet another port. In 2014, these engineers released USB type C. Once again, reversible, USB 3.1 bandwidth, and can even support a little something called Thunderbolt 3, which has a whooping 40 Gbps data transfer rate. It does away with the master slave concept, meaning that it also replaces all connectors, type A, which was replaced since there is little purpose in such a large connector, type B, because it is unneeded without the master slave concept, microUSB since type C is also tiny. There is also mini USB type A, and several other connectors, but I think you get the point. /walloftext | 1 |
8606uj | Biology | With the recent passing of the world's last *male* Northern White Rhino, how will efforts to revive the species continue? It was reported that his "genetic material was collected yesterday and provides a hope for future attempts at reproduction of northern white rhinos through advanced cellular technologies." The last two remaining females are his daughter and granddaughter respectively, and it was also said that they would continue on and use surrogate Southern White Rhino females, but wouldn't that create another, different "subspecies?" (Not sure if that was the right word.) | I believe sperm was extracted from white rhinos in the past, so in-vitro fertilization of the existing females may be possible. | 2 |
dymzkt | Mathematics | what exactly does the square root of a number represent? | If you literally drew a square with sides = the square root of a number, then the area of that square would equal that number. e.g. 2 is the square root of 4, and a square with sides = 2 (whatever units, inches, miles, it doesn't matter) would have an area of 4 (of the same units). | 3 |
jut6bt | Physics | How do small birds not blow away when it’s windy? It’s really windy here today and I’m watching this bird feeder swing back and forth. How do the really tiny birds not blow away in the wind? Do they hide in a nest and grip onto it to stay still? | They get blown all over the place when the wind gets gusty. As long as they aren't close to anything, they can just compensate by flying into the wind. You'll notice though, sometimes they will have a pretty hard time landing on small targets like branches when the wind gets bad, and at a certain point, the wind is just too fast for them to fight it, and they find somewhere sheltered to wait it out. | 6 |
5vi0m3 | Other | Why is the majority of girls handwriting nicer looking than boys? | Social norms. There is no social reward to be gained by a boy who writes neatly. In fact, teachers often subconsciously encourage gender stereotypes that allow for "boys will be boys" and "girls need to be little ladies" gendered expectations to become ingrained. A girl that with poor penmanship is going to get a lot of negative attention from peers and teachers that boys simply do not experience. Girls with excellent handwriting are often singled out and praised (social capital) in ways that boys are not. | 42 |
f7ew9k | Physics | How do direction work in space because north,east,west and south are bonded to earth? How does a spacecraft guide itself in the unending space? | Earth based directions (North/South/East/West/Up/Down) don't work, so we create a new "frame of reference". A frame of reference is a way of looking at and measuring things. Walking around your neighborhood, you use N/S/E/W, but if you were walking on a huge cruise ship sailing through the ocean, you would use Fore/Aft/Port/Starboard, no matter which direction the boat was pointed. We would say we are moving towards the port side, even if the boat is moving west, so Pot is actually south. We would say we're walking towards the Port side at 1.6 km/hour (1 miles/hour), even if the boat is moving forward through the ocean at 32 km/hour (20 mile/hour). In the same way, we can create different frames of reference for outer space. One frame of reference when you are orbiting close to earth, another when you are far from earth and orbiting the Sun, another when getting close to the moon / Mars, etc... A great and fun way to experience this is to play Kerbal Space Program. | 14 |
8bbawq | Biology | Why do some foods, like corn, not digest? | Generally the portions of he food you can't digest contain the seeds. They are surrounded by a fleshy exterior that contains nutrients. As a result you eat the food, and the seed will pass through in your waste, which provides nutrients for it to grow. | 2 |
6cm8wu | Repost | How do hairs know when they've grown to a certain length? | When you find out, could you tell my nose hairs? | 3 |
8l5myz | Culture | How do nascar/Indie races have some of the highest attendances in sports when they don’t seem all that popular compared to many other sports? | Because a racetrack is bigger than a football field. More room equals more seats. Also note there are fewer events and ticket prices are lower than many other sports. Total attendance and total revenues are much less than football or basketball. | 3 |
haq5ik | Other | What is the difrence betwen jail and prison? | These are mostly used interchangeably but they make most sense when used considering the duration spent. Jail is generally short term while Prison is where one goes for a long duration | 3 |
nla754 | Biology | Why are pills usually the same size for different sized people? I’m eating pollen medicine. They are small pills and I should eat one per day. I realized that I, as a big dude has the same dose as a small tiny woman would have. One pill per day. Even if I have three times the mass. Why is it this way? | Medications - especially the ones that doctors trust patients to take unsupervised - are formulated with big safety margins on both sides. Firstly that taking one or two or even the whole bottle too much won't kill you / do lasting harm (unless you do it repeatedly) and that the medication will be effective even if you're overweight or have issues effecting absorption (like they assume you're still likely to drink milk close to taking an antibiotic). In hospital - where you are dealing with medications that need to be more precisely administered - part of the nurse's duty is calculating the precise dosage taking your weight into account. And the hospital is controlling your diet so you won't have had things like milk, grapefruit or alcohol that can interfere with medications. | 4 |
6ssxso | Biology | Why do heavy drinkers not get hangovers compared to occasional drinkers who do get them? | Alcohol is essentialy a poison to the human body. The more you drink the more you build up a tolerance for it. That's why people that drink often dont get drunk as easily nor have as bad hangovers, while people that don't drink often have a low tolerance so they get drunk easily and the hangovers are worse because their body worked harder to try and expel the poison. | 2 |
kb6bbn | Physics | How is it that in a nuclear reaction the number of protons and neutrons stays the same but some mass is converted to energy? The mass of what is converted to energy? | Welcome to quantum physics, its gonna get weird So we'll start by looking at the weights of some isotopes Carbon 12 is the definition for atomic weight. It has 6 protons, 6 neutrons, 6 electrons, and weighs in at 12.000 atomic mass units (u) as it is the definition. Oxygen 16 has 8 protons, 8 neutrons, and 8 electrons so it should weigh in at 16 u right? Nope, 15.9949 u. Weird, where's the missing mass? How about we go lighter now, Beryllium 8 has 4 protons, 4 neutrons, and 4 electrons so it should be 8 u but its 8.0053 u... Where's the mass coming from and going to? Binding energy! E=mc^2 covers this directly. The energy used to hold the protons and neutrons together in the core adds to the mass of the atom. Iron has the lowest energy per nucleon (proton/neutron) so as you split heavy atoms like uranium you end up with products who's mass doesn't add up to the same as the uranium you split. Similarly smashing two hydrogen atoms together gives you a resulting atom that is a bit lighter than expected with a high energy photon carrying away the energy that isn't needed anymore. | 2 |
9ac1lh | Biology | There are multiple species of bears, sharks, monkeys, etc. How come there are not multiple species of humans? | What we call "bears" is not a Species but a Family (taxonomically speaking); and what we call "sharks" isn't a Species either, it's a Superorder (again, taxonomically speaking). When you say humans, you are talking about a Species, not about a Family or a Superorder. The Family humans belong to is "Hominidae", and there are **eight** species of Hominidae according to Wikipedia: * [The Bornean Orangutan]( URL_4 ). * [The Sumatran Orangutan]( URL_5 ). * [The Tapanuli Orangutan]( URL_3 ). * [The Eastern Gorilla]( URL_7 ). * [The Western Gorilla]( URL_2 ). * [The Common Chimpanzee]( URL_1 ). * [The Bonobo]( URL_6 ). * [The Homo Sapiens (Humans)]( URL_0 ). So it's not true that there are only one species of *us*, there are eight of *us* at this point of evolutionary history. There were more but they are extinct now. | 8 |
74wntd | Biology | Why does cold water help burns? You would intuitively think that the burn damage is irreversible and not affected by the temperature of the skin after the burn. | There's a few reasons that cold water is recommended for burns. First, depending on the burn and what caused it, there can be ongoing damage occurring- kind of like how scrambled eggs keep cooking for a bit even after you take them out of the pan; residual heat can still be doing harm after you've moved away from the source of the damage. If you were burned by something other than direct heat, like an acid, chemical or other damaging material, the water can help remove any traces remaining, **DEPENDING ON THE CHEMICAL**. You may want to *avoid* water in some situations, but that's usually going to be in scenarios where you should be trained and wearing safety gear. Additionally, cold water helps soothe the pain by numbing it. Also, it can help reduce and prevent immediate swelling. | 2 |
l2205q | Technology | What is so amazing about the F35 to warrant its $1T budget? Do the benefits really justify the R & D costs? I've read a number of different estimates for the F35 project but everything seems to fall in the ballpark of $500B to $1T. I've seen some pictures (renderings?) and it just looks like another F16. What in the world is so great about this jet to justify this amount of R & D expense? | The F-35 is not a single airframe but rather three different airframes which have different capabilities. This is so that they not only replace F-16 but also F-18, F-15E, Harrier, A-10, among other different airplanes used today. The US Air Force is putting all their money into making the ultimate fighting aircraft that can be configured to do anything. Just like the US Army did with the development of the Bradley Fighting Vehicle. Edit: list of aircraft it replaced were corrected. | 4 |
643mln | Physics | When a lightning strikes the ocean, how far should a person in the water be from it, to avoid being electrocuted to death? | I would assume you could probably be a few yards away from point of impact as long as your below the surface. Although water conducts the electricity, without a way to concentrate that energy then the energy would quickly dissipate by depth. However the surface of the water would instead channel and convey the current over a lot farther area. If your on the surface when thunder strikes you would need to be 50-60 yards away as to not die. | 3 |
ce8onv | Chemistry | If oxygen isn't very flammable why is it needed for fires | Let's answer by looking at what happens during "fire", and why it happens. We'll use a piece of barbecue charcoal as an example. Charcoal is pretty much just a mass of carbon atoms that's squeezed together, left over in the shape of the dried and charred oak wood that it came from (or sometimes crushed into a brick shape). Those carbon atoms are normally quite happy at normal room temperatures and the coal kind of just sits there. It's stable. But heat it up a whole lot and the extra temperature causes those coal atoms to get excited. If you give them enough heat to pass something called an activation threshold, they now want to combine with something else to become a different chemical that's even more stable. (It's kind of like a round rock on top of a hill that's fine until someone gives it a shove, and then you have an avalanche.) If you give them one of the chemicals that they're willing to combine with, the carbon "reacts" with that chemical to become something else. A super common chemical that does this is oxygen. Add it and heat to carbon, and you get carbon plus oxygen becoming carbon dioxide. And there's a bonus: the heat that this combination produces is higher than the heat that this combination requires to get going... so the edges and corners of your charcoal produce a lot of heat because that's where the oxygen can reach the hot carbon the best. The same thing applies to candles, sticks of wood, gasoline, and so on. Those aren't just simple carbon, they have hydrogen and other stuff in them too... but the same thing happens when you feed enough heat in - the hydrogen gets excited and wants to combine with oxygen to form water because it's more stable, and that process releases extra heat. So oxygen is needed for fires because it's an ingredient that is needed in the recipe, and when it combines in that recipe it releases more heat that keeps the process going. Remove the oxygen and you remove not only an ingredient, you remove the thing that creates heat too. This causes the fuel - carbon, hydrogen, whatever - to cool down so much that it's now stable enough that it won't react any more. To get it going again you have to re-light the fire. | 3 |
a2r023 | Physics | How is a single wall power outlet able to power 5 devices using an extension cord? If I were to connect, say, 100 devices to a single power outlet using multiple extension cords, will they all work? | A given device doesn't necessarily use all the rated capacity of a single outlet. Here in the UK most ordinary wall outlets are rated at 230 volts, 13 amps. 13 * 230 = 2990 watts So as long as the total load that I have connected to that single outlet doesn't exceed 2990 watts of power, then all will be fine. That could be a hundred phone chargers, but probably only one decent sized fan heater, or maybe a couple of hair dryers. This is why the general wisdom is to not connect too many multiway extensions to a socket, not because you'll definitely overload it, just because it's *far easier* to overload it if you have eight outlets to connect to instead of one. *edit* I have one of [these]( URL_0 ) hooked up under my desk, which is fine because my whole rig, when it's running flat out, consumes about 400-450 watts. As I say **one** UK outlet can output 2990 watts before you're overloading it, so I've got a huge overhead left yet. | 4 |
kjgxdc | Biology | How do other mammals know when they are pregnant? | Hormones change with pregnancy. That's how they'd know. What they do because of it changes greatly from animal to animal however. | 3 |
iklttc | Economics | How wealth is not a zero-sum game ? | It's not a zero-sum game because the economy can grow in size. The amount of value in the world is not fixed. As time marches forward, our ability to extract more resources increases, and we learn to use those resources more efficiently. We also develop new ways to efficiently convert the time of human labour into productivity (think about how much faster accountants are at their jobs since the invention of spreadsheet software). Many companies (and their owners) generate their wealth by doing these kinds of endeavors. Their own personal wealth is gained from the growth of the overall societies wealth | 9 |
jtva5t | Biology | if standing up straight is supposed to be proper, why does slouching seem so natural? I try and stand/sit up all the time but it always feels forced while slouching just feels right and comfortable. How is that? | Proper posture is better for your body in the long run. Slouching feels easier because you're using less muscle to stay upright. But decades down the road, slouching may be your only option if you don't avoid it now. | 4 |
92yhce | Biology | Humans have a mitochondrial Eve. Do other species have a mitochondrial Eve? Do humans share a mitochondrial Eve with any other species? | short answers, yep, yep. Mitochondria are (theorised to be) a single celled organism that some ancient single celled organism absorbed, and rather than digesting and dissolving it, allowed the mitochondria to survive inside, producing energy. Cells cant produce new mitochondria, all we can do is copy an existing one. This is actually the MAIN reason for reproduction to work the way it does - the female provides an egg, and the most useful part of the egg cell is the mitochondria. this also means that if you had good enough tools, you could measure the mitochondria mother back, billions and billions of years, to the origins of complex life, to the first mitochondria that was ever absorbed by another cell. However that also assumes that it didnt happen multiple times in multiple places. The reason you can say with reasonable confidence that humans all have one mitochondrial eve, is that in the grand scheme of life, we havent been around all that long | 1 |
8m7vun | Other | Why are hospital buildings (in the US) generally built taller than surrounding city property? Is it to create a conspicuous visual landmark for ambulances and random people in emergencies to find more easily? Is it because of how a hospital functions internally? | I'm surprised that nobody has mentioned this: Most hospitals (if not all) have a helicopter landing pad on the roof somewhere, for when patients need to be airlifted due to emergencies. It would be dangerous or difficult to land that with taller buildings right next to it, and making the hospital taller just gives more space. | 8 |
kc4nek | Biology | If common cold is a viral infection, why does it usually happens on winters? | It doesn't, it's just much more common during that season. Winter weather forces humans together indoors, sharing the same air and personal space. The cold, dry air also dries out the mucous membranes and allows viruses to survive longer in the air. This causes viruses like the cold and flu to transmit much more readily. | 1 |
7qkbz8 | Other | How are online credit card transactions considered safe when the merchants solicit information that they can use to make purchases elsewhere? | Merchants online generally don't get the CC information. It is run through a company like Moneris or Global Tech etc. who process the transactions. All the the company sees in many cases is the last 4 digits of your CC. | 13 |
dpz1mn | Technology | How can the chance of rain be 10% when it’s pouring outside? | Forecasts are done over an area, not a point location. It might be raining at your location but not 2 blocks from you. The percentage is the chance of some place in the area of the city or whatever defined region getting rained on. | 2 |
ckfiut | Biology | How does the heart regulate its beat so perfectly? What is happening to this system when we have palpitations? | Your heart has pacemaker cells that can actually regulate the heartbeat themselves without input from your brain. They start the electrical signal within your heart to beat, and they do so with awesome precision and rhythm. The signal then travels down your heart through a pathway made for those electrical signals, and you get a heartbeat. Your nervous system also supplies nerves to the heart that can increase or decrease the rate that those pacemaker cells fire at (thus changing the heart rate). But the pacemaker cells don't need the nervous system to work. The heart is pretty nifty that way. 'Palpitations' is really nonspecific and can mean anything from a fast heartrate to skipped beats to a heart rate that is just completely irregular. But, overall, these can occur when any of the above steps have issues. There are a lot of different causes. | 1 |
km1iul | Physics | Why can’t you combine a telescope and microscope? This is one of those things that I know doesn’t work, but I don’t know the exact reason WHY it doesn’t work. I remember asking a friend in 7th grade biology why I can’t just put a telescope up to a microscope to see even more detail, but he just laughed and no one I’ve ever asked has given me an answer | A microscope relies on photons illuminating a small area to show an image of the really small and minuscule. A telescope relies on as many photons as possible over a large area, as light tends to scatter over large distances relative to their source. Also exposure is important as to gather as much light as possible over a given amount of time so the photons can in essence paint a picture on whatever medium your using, be it digital or otherwise. | 3 |
6hq18w | Repost | Why are cologne commercials abstract and nonsensical? | they're advertizing something that cant actually be conveyed electronically yet (maybe smell-TV will happen someday), so their choices are limited to metaphors and abstractions or "trust me dude, it makes you smell nice" | 4 |
i5hqnv | Other | If a parent dies and has it in their will for their children to be taken care of by a family member, can that family member say no? | Even if the deceased parent states "I want /u/Feral_Geologist" to take care of my daughter" in their will, that is not a controlling document. Custody/guardianship will be decided by a judge. At least that's how our lawyer explained it to us when we had our wills done. | 2 |
8dwotl | Engineering | Why do places like Target and Walmart blast you with air when you pass through their sliding doors? | The air blowing when the doors open makes it harder for flies or flying bugs to pass through. The air isn’t for the people it’s to keep the bugs out of the store. | 6 |
bydbqb | Engineering | Why do window AC units use so much energy? | Window units are actually terribly inefficient. Because they are classified as an appliance the energy efficiency requirements are considerably less strict than with residential hvac systems. Additionally your apartment is presumably older and therefore not well insulated this adds a great deal of thermal load to the space. In general the best option is to leave the system on all the time. Turning the unit off causes the humidity to rise and the structure and its contents to increase in temperature. | 2 |
7tt02n | Mathematics | Why does mathematics work to describe reality (physics)? | Because mathematics is a tool, like language, that is developed for the purpose of describing things. It can describe real things, imaginary things, and things in between. Thinking of math as a distinct subject, as being separate from its environment, is as much a mistake as thinking of English as separate from its culture. | 6 |
6lajev | Technology | How does Facebook (and other social media sites) compile a creepily accurate Suggested Friends list even when you are a new user and have given the site minimal personal information? | A lot of ways. If you have the account signed in on your phone, it can read your contacts and find their Facebook accounts. An obvious way: it looks at mutual friends. If you use apps via Facebook, it could look at other people using those apps, people you've used it with and people nearby who've used it. It could and probably does track the location of users (via IP addresses and GPS) and - if it finds you spend a lot of time with particular accounts - might consider that you were friends. It might also buy data from Google, Yahoo or Hotmail about the people certain people email, and find accounts registered to your frequently contacted email addresses. Finally, it's unlikely but possible that if you create multiple accounts from the same computer, it will automatically associate them with each other. | 5 |
8onxo8 | Culture | Why are so many medical institutions (like hospitals) religiously affiliated? | Because back before the government provided social services, this was done by the churches. The church took caring for people seriously. Some still do. | 1 |
kfijsr | Physics | According to Newtons' third law of motion every action has an equal and opposite reaction. Then how is motion possible? | Actions and reactions does not both apply to the same object. So the objects can move in opposite directions from each other. | 3 |
bd0ps1 | Other | Why does Google know I speak Spanish? | You are extrapolating a lot from one incident. I occasionally get ads in Spanish. I don't speak Spanish. It doesn't require any spectacular level of knowledge (or money) to throw an ad at someone and see if it sticks. | 3 |
7ldsfz | Other | How do flares stop missiles? | ELI5: Flares only work against missiles that are heat-seeking. The flares burn intensely and create a lot of heat which intends to trick the missile into guiding on the flare itself. If the missile stops guiding onto the target aircraft and instead guides on the flare, then the target aircraft survives and the flare served its purpose. | 5 |
n13et8 | Biology | If carbs are sugar, why cant we just eat sugar? Or in other words, why can't humans live of a diet made entirely out of sugar. Edit: Changed description like forst commenter suggested | I mean, you *could* eat refined sugar for a big part of your diet, but there are two problems. One is that refined sugar provides plenty of energy in the form of carbohydrates, but we also need other things such as proteins, fats, vitamins, etc. that aren’t found in refined sugar. Another is that our bodies aren’t adapted to digest exclusively refined sugars - our metabolism uses them up really quickly, and that messes with our insulin levels to the point that we can eventually develop diabetes. It would be a bit like replacing the firewood in your fire pit with a tub of gasoline - it will still burn and provide heat, but that doesn’t mean it’s interchangeable. | 1 |
974bu7 | Technology | I read that some sub marines are powered by nuclear power such as Uranium for years before having to be changed. Why cant our normal everyday electric also come from Uranium? | It can and it does. Nuclear submarines, nuclear aircraft carriers, and nuclear power plants all generate electricity in the same way Some countries generate a significant amount of their power from nuclear energy. France generates 40% of its electricity from its 58 nuclear reactors. Expanding capacity is hard. New nuclear reactors are very expensive due to all the regulations and safety features that are required. The local population doesn't understand them and is generally afraid of the radiation(which doesn't get out) and pushes back against the construction of new reactors and power plants. We're more focused on expanding solar and wind capacity these days as they have far far less political push back and are significantly quicker and more cost effective in the short term than nuclear power | 4 |
8uqr61 | Economics | Why do some companies create different brands even though they all operate in the same industry? example. Kroger owns kroger, ralph's, and food4less grocery stores. Even their individual phone apps are duplicates of each other (design wise). I understand some stores are only available in certain part of the country but wouldn't it make more sense for them to have one brand? esp if they all, essentially, offer same products. to have greater impact in terms of brand recognition? | Lets say you make a red product and sells really good. There is a chance for a blue product, but some people in your team say that if you do the blue product too, it will take market share from your red product. The argument I learned is that if you do not do the blue product, your competitor might or actually will do it, taking the market share from the red product anyway. So better you than the competition. | 4 |
6e549i | Culture | Why a being a convicted felon takes away a person's right to vote in the US | To quote from [The Straight Dope:]( URL_0 ) "The simple answer to your question is that felons can't vote is because voting is a civil right and you forfeit certain rights, temporarily anyway, when convicted of a serious crime." Furthermore, "convicted felons have been denied various privileges granted to other citizens going all the way back to ancient Rome and Greece — this practice is laced throughout the common law that serves as the basis for U.S. law." Finally, the 14th Amendment gives permission to the states to deny the voting rights to felons. If you want a longer answer, read the linked article, it is an easy read and pretty thorough. | 5 |
76jxgh | Culture | I keep reading that Greeks didn’t have a word for blue and humans couldn’t see it until modern times. How is it possible that our ancestors didn’t see the color blue? What did the sky look like to them? The ocean? | The ancient Greeks did not classify colors by hue, but instead by whether it was light or dark. κυάνεος (kyaneos), was used for dark blue, also dark green or violet. While Γλαῦκος (glaukos) was used for light blue, also light green and yellow. Why they did this, no idea. In modern Greek we do have a word for blue, it is μπλε, pronounced ble. | 5 |
iby3ox | Chemistry | If an alpha particle is a helium nucleus, how come helium doesn't cause radiation sickness? Or is it to do with the speed that alpha particles travel at during fission reactions | You won't die if you touch a bullet. Same goes for alpha particles. They aren't dangerous because they are helium nuclei, they are dangerous because they are moving extremely fast and can break molecules in the body if they collide with them. | 2 |
6enn0w | Physics | Why does the flame of a candle go up? | The flame of a candle is about 1200 F. Hot air rises because it is less dense so this pulls the flame upward. Fun Fact: There have been experiments conducted on the space station testing flames in microgravity. Since there isn't really an "up" without gravity, the candle flame spreads out in all directions and eventually starves itself of oxygen. [image]( URL_0 ) | 3 |
8l98i8 | Economics | If corporations are legal "persons", why are they taxed at a special corporate tax rate, instead of the (usually) higher income tax rate? | Taxes are a weird sort of tool. Lets say you are the Mayor of city 'X'. You have a job problem, people that live in the city aint got one. Tax revenue is utter shit because unemployed people don't really pay taxes. Company 'Evil Empire' swings by and they say, 'We want to build a factory and employee 10,000 people. But let it be known, there is nothing special about city 'X', Cities 'Y' and 'Z' have the exact same problem as you - we are only going to build one factory. So you say, 'Okie Dokie. If you build we will let you run your factory tax free for 10 years'. The neat thing is that those 10,000 people - at least those within city limits - are now employed and as such are paying more in taxes then what they did before. So for the next 10 years tax revenue goes up, but year 11 it really goes up cause the agreement has aged out! Taxes are a tool. I think by seperating types of taxes it allows people to do things like this. -------------- Having said all those words, I am a supporter or destroying our current tax structure and redoing it from the ground up. I am simply describing how things work, not necessarily endorsing it. | 14 |
eov8h8 | Biology | Why do certain body muscles get stronger with stress and healing (including broken bones), but others like eye muscles get weaker? | It's a different type of stress, so to speak. If you over-exert yourself in any endurance training you will lose muscle mass as well. The reason it recovers and grows stronger is because you're pushing the muscles' limit for a brief period of time and letting it rest, while when you "exercise" your eyeballs you're doing nothing more than make them work for much longer periods of time than they can handle. If you go marathon running out of the box without proper escalation and without rest you will start the catabolic state and your leg muscles will get smaller (along with many others). | 1 |
9d1dsf | Biology | Why is protein the only energy source that can be used to build muscle? If all the macronutrients are just different forms of energy, what makes protein unique in its ability to build muscle tissue? Is it something that has nothing to do with energy? (i.e. proteins that go towards muscle growth are not consumed as energy?) | You don't need Protein to build muscle, strictly speaking. You need amino acids which your body can't produce by itself. These are called "essential amino acids" Protein is the choice supplier of 'em | 6 |
65orpd | Other | Who decides what products go on sale in stores? The store or the manufacturer? | Not every business works the same way but this is how I do it at my store. Sometimes we put something on sale because we have too much in stock. Sometimes things go on sale because they aren't selling very well and we want to get rid of them for something else that will. Sometimes we make a deal with the producer to buy a certain amount of a product to get a special price so we can put the same product on sale cheaper than a competitor can sell it for. Sometimes the producer puts a product on sale for whatever reason and they leave it up to the individual store to decide whether to pass that sale onto customers or to pocket the extra margin. | 1 |
ad7401 | Biology | (Almost) all diseases downgrade your daily life. Are there any diseases/genetic advantages which can boost your daily life without artifical help from outside the body (medicines etc.)? | There's a rare genetic mutation that makes people need significantly less sleep. Not a disease, that'd be dope tho | 6 |
o89u59 | Biology | Why do eyes play tricks on you at night? Like showing things that aren't there? | Brains are *really* good at noticing patterns. Being able to pick out, say, the eyes of a predator staring at you in the darkness through the vegetation means surviving when others die. The conscious picture you have isn't objective reality, it's what your brain has filtered and processed to search for those crucial signs of danger, or food, or shelter, or anything else you need to survive. At night, your eyes can't collect as much light so what you're seeing is less clear. Despite that, your brain is still trying very hard to look for patterns. It's looking *so* hard that it sees patterns where there aren't any. | 2 |
7k3fu1 | Other | How do neutral countries like Switzerland not get invaded by other countries? | I think you're misunderstanding the term neutral to mean pacifist or something. If they were invaded they would defend themselves just like any other nation. | 6 |
mzbky4 | Other | Why aren’t hats allowed to be worn in public schools? | For the US, two reasons come to mind. It is/was considered rude to wear hats indoors in many parts of the US. Hats can, or are beloved to, be used to signify gang relations. | 2 |
965lzf | Repost | Double Slit Experiment. I have a question about the double slit experiment, but I need to relay my current understanding of it first before I ask. ___ So here is my understanding of the double slit experiment: 1) Fire a "quantumn" particle, such as an electron, through a double slit. 2) Expect it to act like a particle and create a double band pattern, but instead acts like a wave and causes multiple bands of an interference pattern. 3) "Observe" which slit the particle passes through by firing the electrons one at a time. Notice that the **double band pattern returns, indicating a particle again.** 4) Suspect that the observation method is causing the electron to behave differently, so you now let the observation method still interact with the electrons, but do not measure which slit it goes through. Even though the physical interactions are the same for the electron, it now **reverts to behaving like a wave with an interference pattern.** ___ My two questions are: **Is my basic understanding of this experiment correct?** (Sources would be nice if I'm wrong.) and also **HOW IS THIS POSSIBLE AND HOW DOES IT WORK? It's insane!** | 1. Yes, but your concept of observe is incomplete. Firing an electron one-at-a-time doesn't really help you know where the electron went. To observe which slit an electron went through, you'd shine a light just behind the slits, and the electron would collide with a photon which is detectable. 2. Nobody knows, we just have theories. This is one of those things that, if it doesn't blow your mind, you don't really understand it. The way I tend to think of it is that they travel as probability waves, and events can occur which cause them to collapse back into a single point again. Then they'll travel as a probability wave again. Probability waves can interact with themselves and each other, hence the interference pattern when it passes through two slits. So when an electron interacts with a photon in the case of us "observing" them, they collapse into a point, then go back to traveling as a new probability wave from that point. So if you cause them to collapse back to a point on the other side of the slits, then you lose the interference pattern caused by the slits. Note that in my internal idea of what's going on, the speed of light or the direction of time is being violated. The entire wave of probabilities collapses at once, no matter how large it is. So either it happens at infinite velocity, or something is going backwards in time and removing the rest of the probability wave. | 11 |
idyybo | Technology | Why can't Wi-Fi be transmitted the same why mobile service is, via a tower or satellite to make it widely available? | Wi-fi isn't good at penetrating things like walls and is pretty much line of sight, compared to cellular frequencies. Coverage comparable to the cellular network would require a lot of antennas. | 4 |
8fbgc2 | Biology | How do doctors and nurses take care of sick people without getting sick themselves? Or do doctors and nurses get common colds and bacterial infections all the time? | Ed nurse here— every time I start work in a new er I have a period where I get sick every couple months. Started a new job late last year, got a stomach bug, the longest cold ever, then influenza A all before February. I do all the infection control stuff I’m supposed to, I just have a shitty immune system. And nursing is such a backwards field; they give us 3 sick days a year and we have to come in or get written up if we get sick a fourth day. We’re around immunocompromised people! It’s insane. I can’t get sick again until Halloween without getting written up, so 🤞. | 29 |
78tqmn | Biology | Why are human babies so useless compared to other animals? | Human babies are born relatively earlier than a lot of other mammals. This is due to the size of the baby’s head and mother’s pelvis. If human babies gestated longer, they would become stuck. | 1 |
5ox11k | Technology | Why are fire animations, fogs and shadows in video games so demanding for graphic cards? | A lot depends on how all these elements are handled in a game. Best case scenario: - The fire is a simple object, animated in a 3d program and let loose in the game. The animation loops and it's quite noticable but you can get away with it. - The fog is just things in the distance getting blurrier. Looks quite bad but it's cheap. - Only static (non-moving) objects cast shadows, no dynamic lights. This might sound like a lot of assumptions but it's not entirely unrealistic and there certainly are games which can use this simple model. It's very, very cheap. Worst case: - Fire is made using multiple particle systems including multiple types of flame, randomized smoke, lights, dust and small elements flying around wildly. - The fog is also a large particle system with added blur effects - Multiple lights with multiple dynamic objects casting dynamic shadows This model is used in games with better graphics and there are multiple performance concerns. I won't go into the details but the main issue is that many of the effects require multiple passes which basically means the image you finally get on the screen needs to be drawn multiple times by the GPU. First object geometry, then lighting, then shadows, then particles, then special effects like antialiasing, bloom, ambient occlusion etc. and if you have a lot of those they can easily become a GPU bottleneck. Source: Make games. Tried to be ELI5 I know this is an oversimplification. | 12 |
has26y | Other | When somebody robs a bank what happens to the people who had money in that bank? | Banks don't store money for you, not unless you are keeping your money in a safety deposit box. Banks borrow money from you, and return it to you whenever you ask. Any cash sitting in their vault isn't "yours" or anyone else's, it is what the bank keeps on hand to do business. If it gets stolen, it is the bank's problem, not yours, in the same way your brother-in-law's car getting stolen doesn't change the fact he owes you $20. | 3 |
6kxvdu | Biology | Are all the environmentally conscientious counties just wasting their time with their climate change fighting efforts if other major polluting countries don't care and are doing nothing at all? | Climate change is a matter of how much. So even if other people are making it worse, you can still choose to make it *even worse* or to reduce your part. | 2 |
npqxut | Engineering | how do water wells work? Why did medieval people know where to build them or why they provided clean drinking water? | My home has a well (and septic) and my water literally just started flowing again 10 minutes ago. I learned a LOT about residential wells over the past 72 hours. Once the drillers find an aquifer (about 620 ft down for us) they install a pump at the end of a very long string of steel and PVC pipe with a power cable running alongside it (about 500’ down for us). The power connects to the house (like any other power circuit), the pump starts running and is connected to a switch & pressure tank. The tank is pressured (with air) to between 30-50 PSI and this creates water pressure in the home to fill hot water heater, toilets, go to faucets, etc.. It was surprising how relatively straightforward (yet expensive) the process and equipment is. | 13 |
8pzs66 | Other | If pasta is made of the same things (flour, egg, water), whats the point of the dozens of shapes? | /u/apoorva63 touched on one part: the sauce. However this is not the end all. All mexican food is just the same stuff in a different shape right? Pasta goes back to the old country. Pasta is the main piece not the sauce. Pasta made from scratch is somewhat time consuming, and in that long process many home cooks (moms/wives) would get a little creative with their pasta. Angel hair, linguini, spaghetti, capellini, etc for the most part are the same but came about in different regions of italy. Why are they still around and just have one? Why have pepsi and coke? Just like in the US with soda, consumption of a particular pasta is regional based in italy. Texture also plays a vital role, the difference between a round noodle like spaghetti and a flat linguini or fettuccini have practical reasons as well. Sight is another. Cooking is an art and should be beautiful. Great dishes stimulate all 5 of the senses. | 12 |
jmteuv | Biology | Why does our breathing pattern change once we fall asleep? | Our automatic breathing pattern is determined by feedback from sensors in our body measuring things like oxygen and carbon dioxide levels, and the brain uses that information to determine the lowest breathing rate that will still get enough oxygen to the body. When we sleep, we're in a state of lower energy demand, with our muscles dormant. Therefore, our oxygen demand is much lower and we don't need to breathe as much when our automatic breathing pattern takes over. | 1 |
7no1jz | Biology | How are allergies developed later in life after years of not being allergic to that thing? | Oral allergy syndrome can be because of pollens or proteins. An allergist can do a skin test to find out what it is that is causing the reaction. I've been developing worsening OAS the last 10 years and can only eat a few fruits without a reaction and that's with taking 4 fexofenafine per day. According to my allergist it's common for adults to develop varying degrees of it usually due to hay fever and the cross-contamination of pollens. | 9 |
b37g2n | Economics | Why are most jobs today paid at an hourly rate rather than how much the person worked in that day? | It is significantly less effort on behalf of both the employer and employee to record, report, and verify hours worked vs productivity. Even if your job has consistently quantifiable metrics it would be a pain, and lead to complications with your responsibilities. Lets say you work at mcdonalds. How would you (or the company) value number of tables cleaned vs number of burgers made (does it depend how dirty the table was to start? If not its not worth it to clean the really dirty ones right? Time spent vs award achieved doesnt work, and if it does then how does management know how dirty it is.) Would the employee need to keep a tally through the day? Would time spent tallying count as a paid for task? How would a manager verify tasks which have no way of knowing how much work was done (cleaning for instance)? Its much much easier to keep everything consistent and easy | 2 |
a2igxr | Physics | how do we know what's under the crust? How to we know what the layers of earth are? I've learnt in primary school that underneath the crust is the mantle, then the outer and inner core, but how can we prove this if we have never dug below the crust? | By looking at the stuff that bubbles up through features like volcanoes. We can also use data from seismic measurements around the world. As the energy produced by earthquakes moves it will deflect as it goes through areas of different density. By collecting data from all over the world we can get a pretty good idea of the depths of different layers. We can also measure meteorites in our solar system older than the earth's crust to get an idea of the likely composition of the earth. | 3 |
707jhj | Biology | Why is it hard for people to change thier beliefs? What causes us to grip on to things that have been proven to be false? Wow! Didn't expect this much attention! There's lots of great responses here. The reason behind my question is that it seems really easy to say, "oh snap I guess you are right and I'm wrong", which is apparently hard for people to do. This is true for me in pretty much everything. I just was wondering why it is difficult for others to do. Lots of good reasons here though! | It depends one what level of belief you mean. If we are just talking about a simple belief like trivia, our resistance to accepting that we're wrong is likely due to reputation. That is, if we are shown to be wrong about something, the implication is that we are not reliable. Think of it in evolutionary terms. Much of our pre-history involves developing trust between people. An untrustworthy person could steal from you, kill you, or otherwise use you for their gain and turn on you when convenient. Earning and demonstrating trustworthiness as a reputation would have been important to survival. Those who proved untrustworthy, such as liars, could be punished, killed, expelled from the tribe, or even just ostracized and not selected as a mate. All these mean they were less likely to survive and reproduce. Those predisposed to fearing being judges as unreliable, and who instinctively acted to protect their reputation, would have reproduced more to pass on their genes. This is why "saving face" is so important to both individuals and cultures, especially historically. People would kill others who questioned their honesty and integrity: duels, honor killings, and so forth. Even the parts of culture where challenging somebody's claims or confronting people is considered impolite is built on this notion of protecting reputation. So changing belief is an admission that you were wrong and that your claims are unreliable. Sometimes that instinct can be far too strong in some people, unwilling to admit to any mistakes. It may depend on whether you are alone in the belief and everyone is against you, in which case maintaining your position risks lowering your status in the group, or if you have a "tribe" of believers backing you up and defending the belief *raises* your status with them. If we're talking about a fundamental belief like a god, political basis, or the nature of how things work, and a whole collection of other beliefs derive from it, all of the above is still true but there is a complicating factor. Now accepting that you are wrong means much of your world view is all wrong and needs to be re-built from scratch. That can actually be very disorienting to deal with. We often call this effect, "cognitive dissonance" when we realize our beliefs are inconsistent and feel disoriented and confused about it. You can think about belief systems as a "locally" consistent collection of beliefs. Like if you have. A religious belief in a god and you understand how people, society, behaviours, history, nature, and so on all derive from that. If you then challenge that this god exists, none of your other beliefs make sense. You now don't understand anything you thought you did. Your have to re-learn why people act the way they do, how the world works, how you should behave, etc. It's a lot easier to just dismiss minor challenges to core beliefs, and use your larger understanding as protection against challenging it. You also have a whole social network that believes the same things so you feel comfortable maintaining the belief. Challenging it just does you no good in any practical social terms, and causes great cognitive and social harms to you. You won't *want* to challenge it, and even be scared of that. But, we all have these inner thoughts and may lead you to question core beliefs, perhaps driven by outside information or because you want to come up with good answers to fight back against a challenger and discover there are no good answers. You then have problems to deal with, like all derivative beliefs and what to do about your life being tied up into this belief system: friends, family, job, culture, etc. Clergy who lose faith have a real life decision to make as they have to start life over, including job skills. Political parties can act like religions too. They start to take on collections of dogma, and challenging those beliefs makes you a traitor to the tribe, and your social circle and position in it will suffer, especially if you are a politician who has a similar dilemma as clergy. Sometimes life is much, much easier to refuse challenging your beliefs. The exception is, of course, when you have a social culture where challenging beliefs is rewarded and praised, like science. That is hard to instill in people though, largely because it goes against our tribalist instincts. It's a lot of hard work to have social value in a culture where challenging beliefs is rewarded, as that takes a lot of education, thought, and intellectual prowess. A culture of defending beliefs is easier because all you have to do is repeat them and become aggressive or violent against challengers. | 33 |
5qrxdx | Technology | Can someone please explain how Jurassic Park (1993) was visually so ahead of its time, it seems almost comparable todays visual effects? | They spared no expense. But seriously, there's a lot less CG in Jurassic Park than most people think. Today, it's quite common for the only live action element in many shots to be the actors. If JJ Abrams (hardly the most CG reliant director currently working) were to remake Jurassic Park today, he'd probably feel forced to engage in a full-on CG fuckathon for sequences where Spielberg simply did not have that option. Spielberg was, instead, forced to use every cinematic trick in the book to hide the short-comings of the comparatively awful CG elements he had available to him. Dark lighting, practical effects (models and animatronics), clever cutting... Jurassic Park is a tour de force in all of these things because the CG was still quite primitive. There are only a couple of full-CG shots that take place in brightly-lit daylight (e.g. the Brontosauraus reveal) and these are probably the weakest shots in the film. People today watch Jurassic Park and think they're seeing flawless, state-of-the-art CG, but what they're really seeing is mostly models and animatronics with only flashes of CG to tie the shots together. The CG was weak, but Spielberg hid it's weaknesses like the master he is. Bonus example: Consider the cup of water in the Jeep when the T-Rex is first approaching. > > One other issue that was initially seen as very small turned into a big puzzling problem. As the T-Rex approaches our main characters, we hear it before we see it. In particular, we see a cup of water start to form “rings” from the T-Rex’s approaching footsteps. Spielberg got the idea after listening to loud music in his car and seeing his rear-view mirror vibrate from the heavy bass. He quotes, “I was on my way to do storyboards for Jurassic Park and I never forgot what it looked like when the bass rhythm went off. I thought in the middle of storyboarding ‘hey wouldn’t it be cool if, when the T-Rex began to approach, the low-end vibration of all that tonnage hitting the ground was causing these little concentric circles.’” The crew thought the gag would be really simple to pull off. As it turned out, however, forming these “concentric circles” proved to be much more arduous than anticipated. Everyone on the production team was puzzled. Sound engineers, physics specialists, and wave tank generators were called in and used to try to achieve the circles, but to no avail. Finally, a solution was found. Michael Lantieri, who was part of the special effects team, quotes, “The night before the shot, I’m at home and I’m still playing around and I took a guitar that I had at home and set a glass of water on the guitar and plucked the string, and it vibrated and did it.” So in the end, the gag was achieved by feeding a guitar string from the cup through the tour car down to the ground, where a guy laying under the vehicle plucked the guitar string (Jurassic Park DVD). [Source]( URL_0 ) Directors often have a vision and go to great lengths to see it realized. However, I guarantee you that Michael Bay isn't going to call in physicists to help him make concentric rings in a cup of water (or to make realistic action scenes, apparently). He's just going to CG that shit and, most of the time, people won't even notice. CG has gotten really good at fixing seemingly small things that cause great pain for the production crew. I don't point this out to denigrate CG or directors today (except maybe Michael Bay), but rather, to illustrate how impressive it was for a director like Spielberg to pull off a film like Jurassic Park that still holds up so well, in spite of the technical limitations of his day. | 31 |
7fxkkt | Physics | If the earth is revolving around the sun, and the sun orbits around the center of our galaxy and our galaxy is also moving, How fast are we actually going, all motions combined? | If you're using the rest of the galaxies around us as a reference, the Sun is orbiting the Milky Way at a clip of about 828,000 km/hr. The motion of Earth around the Sun at that point is negligible. The speed of the galaxy amongst the other galaxies is harder to define, since they're all kinda moving around. We're moving towards some and away from others and there's no clear reference. As others said, without a reference point, velocity is truly meaningless. It may be hard to picture on Earth, because that's our reference point in everyday life and we take that for granted when talking about how fast things move. In empty space saying "I'm moving at this speed" and saying "the rest of the universe is moving around me at this speed" are truly equivalent. | 4 |
c2zfpv | Biology | How do fruit flies start? I get that they come from expired food, but what I don’t get is how they appear in the first place. Do their eggs just form or are they already in our food and hatch when the food expires? I don’t know why I don’t understand it but I just don’t haha | Fruit flies don't come from expired food, they are only attracted by it, so when they smell it, they come rushing for it. They dont come FROM the food, they come FOR the food. | 3 |
k30oci | Biology | Why were dinosaurs so huge compared to earths modern inhabitants (humans, animals, ect) ? | The big ones get the publicity. Although there were many large ones, plenty of the family of dinosaurs were quite small, down to a few ounces. In addition, the largest animal to have ever lived is currently still on Earth, the Blue Whale. That is possibly twice the estimated weight of the largest dinosaur. | 2 |
bv4e9k | Culture | why are vehicles insured, instead of people/drivers? | - Some cars are more valuable than others - will cost more to repair - have a higher risk of theft. More desirable - easier to steal. Weak security features - some cars are faster. Higher risk of crashing | 2 |
9qtdne | Biology | Why is swallowing gum bad again? | There is nothing wrong with swallowing gum. It won't digest, meaning it doesn't get broken down, but that just means it will pass through you and out with the rest of your waste. Almost *nothing* will just sit in your system, it either gets broken into nutrients that you use or it continues through your digestive tract. | 4 |
fauzh4 | Technology | What is high and low fidelity in music? | Fidelity is a measure of how closely a copy matches its source, regardless of the medium. Record albums, JPEGs, DNA -- anything that makes copies has a measure of fidelity, of how precisely it matches or doesn't match the original. The higher the fidelity of a recording, the more similar the sound from the recording medium is compared to the original sound. An example of a high fidelity copy would be a studio master. An example of a low fidelity copy would be an MP3, in which details have been "smeared" into groups of similar details, making a less detailed file that still contains the basic waveform shape changes that characterizes that particular noise. Information has been removed, but the overall gist remains the same. A zero fidelity copy would be a recording that sounds totally unlike the original. Like, you recorded a pop singer in the studio but your sound file is the noise of a garbage disposal. The correlation between source and copy is so low it is difficult or impossible to see the connection between them. | 1 |
h9nepv | Technology | how does platforms like Steam or Amazon know if you're using a correct visa card or not if you didn't buy anything with it? | There is a method called the [Luhn algorithm]( URL_0 ) that can be used to check the digits of the card number. The last couple digits of the card number are the result of the Luhn algorithm on the other digits. This is built in as a simple check for errors. | 4 |
jg756z | Chemistry | Why does drinking alcohol when feeling happy makes you happier but drinking while sad makes you feel numb? | Alcohol is a depressant. A little bit will make you feel good but more will make you feel bad. So a a party you're drinking beers and probably doing some shots. The music is loud, you're with people and got food. In general having a good time. After bad news, people tend to reach for the stronger stuff. That combined with bad news can really get you down. Thats one reason why you can't drink while on antidepressants, it reacts badly and stops the medication from working. | 1 |
9ghpg4 | Technology | Why do pictures taken of computer screens from a phone look so weird? They have weird curves and lines on it when I'm zooming in, or rotating the picture. The effect looks somewhat like looking at a wire mesh through another wire mesh. | > The effect looks somewhat like looking at a wire mesh through another wire mesh. Because you're basically doing the same thing. The pixels in the computer screen are arranged in a grid. The pixels in the camera sensor are arranged in a grid. The pixels in your phone screen are arranged in a grid. Because those grids don't perfectly align with each other you see an effect that is called [Moiré pattern]( URL_0 ). The same thing happens when looking through multiple wire meshes, because those are also grids that don't align perfectly. The holes of the meshes are similar to the pixels, the mesh themselves are the spaces between the pixels. **Edit:** to answer a few common questions: The strength of the effect depends on the alignment and relative scale between the grids. So you can reduce the effect by better aligning the photo (e.g. making sure the camera isn't rotated or tilted) and by trying different distances from the screen. The effect is stronger if some pixels from the monitor fall right in the middle of the pixels of the camera sensor or phone screen while other pixels fall in-between the pixels of the camera sensor or phone screen. And since the camera app of your phone will show you a scaled down picture (phone screens may have a resolution of 2-4 megapixels, while phone cameras have resolutions of 12-20 megapixels) you may not see the effect in the preview of the photo but later in the actual photo, especially if you zoom in. In order to prevent the effect you can basically only resort to trial and error. Snap a picture, open it, zoom in at the size you want to use it and check if a pattern is visible. If not, then try again at a slightly different distance, or change the photo resolution in the camera app. Also you can use the settings to show an alignment grid to make sure the camera looks as straight at the screen as possible. | 6 |