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abbmxh | How do games/apps that run at 60 FPS measure time to the hundredth of a second? | Technology | explainlikeimfive | {
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"Most modern engines can separate FPS, which is the visual representation, from engine logic timing. Games that do not split this logic often have locked FPS to make sure you don't get weird behavior. Need for Speed was locked at 30 FPS and people who unlocked it to 60 experienced that the game was actually twice as fast. TLDR: most engines split engine logic timing from visual refreshing.",
"They use your PC's system clock to tell what time it is. Each game is (generally) designed on \"ticks\". If you think of a board game, you can say a \"tick\" = a \"Turn\". Every turn it processes formulas and gives an output.",
"Two components: 1) Game logic is not at 60FPS, only the display engine. Some game engines run at the refresh rate, but that has huge problems associated with it (for instance, a low frame rate can make physics simulations go wrong if you link them). 2) You can use algorithms to determine the exact time something would happen. You can therefore have higher accuracy than the rate at which the physics engine updates. EG: If you are 10m away, and I fire a shot at you at 100m/s, I can calculate it will hit you in 0.1s. You do not need to calculate it every 0.1s to have that accuracy."
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abchzu | Why does video static make the video bitrate worse? | I've always noticed that whenever I'm watching a youtube video or twitch stream where for whatever reason the screen goes to static (usually in a video game) all other things in the video on top of it become very blurry as if the video has a very low bitrate. However as soon as the static stops the quality goes back up. Why is this? | Technology | explainlikeimfive | {
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"Imagine the video is of a plain blue screen with say a red ball moving across it , the data sent doesn't need to change to much except to change the next lot of pixels around the ball, now if it's say black and white static, all the little black and white specks need to be updated each data packet, also why Say at the end of the Superbowl when they release all the confetti it makes the picture look crap."
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7uetbc | how do masks work and are they any better than simply covering our faces with a piece of clothing? | Just wondering how effective surgical masks are at preventing particles from being inhaled. Are surgical masks really effective at preventing the spread of bacteria? (I mean you can still feel the air when inhaling and exhaling) How effective are masks at preventing inhaling woodchips and pollutants given they are frequently used in highly polluted areas ? | Technology | explainlikeimfive | {
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"Most bacteria isn’t technically airborne but is rather spread by small droplets of water that you exhale. That’s what your run of the mill surgical mask is designed to block, if you are dealing with a true airborne pathogen you need to wear a heavier duty mask like [this]( URL_1 ) or [this]( URL_0 ).",
"Masks come in a number of varieties, each designed to protect against different sized airborne particles. If protection from fumes is needed, a respirator with a charcoal filter would be used.",
"As stated in other replies, surgical masks are designed to block water molecules, there are N95 masks that, according to Wikipedia, \"These filters seal are made to seal tightly around mouth and nose and is made of material certified to block 95% of particles 0.3 μm or larger in diameter, roughly the size of a single virus\" there are also respirators that can be used with many different types of cartridge to protect the wearer from chemical contamination or dust particles like sawdust. (the fine sawdust is dangerous, the larger woodchips aren't as serious) and those work really well, the cartridges will get filled and have to be replaced. In highly toxic areas or areas with low oxygen concentrations, a SCBA or something similar would be necessary, like firefighters wear."
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7ufthi | Why do you see scientists use electron microscopes for small bugs when normal microscopes can even see cells? | I remember seeing something about how an electron microscope works on this subreddit, and ever since I saw that i have been wondering why scientist use electron microscopes to see bugs when normal microscopes can see cells. I would also like to know if this is the only thing this technology is used for. Ex: URL_0 | Technology | explainlikeimfive | {
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"That electron microscope shot is zoomed out far so you can see what you're looking at. 80x is barely any zoom, they can get beyond 10,000x with a well prepared sample which is far beyond an optical microscope. [This is a far better demonstration of it's capabilities]( URL_0 ) Electron microscopes are used when you need to see really tiny things. They're often used in failure analysis of electronics so you can see which tiny transistor blew up.",
"Conventional optical microscopes are really good at looking at flat things. But the higher the magnification gets, the worse the depth of field gets. This is the height range where the image is still in focus. This is fine for cells because you can put them between 2 pieces of glass to remove any height difference. But if you tried to look at something like an insect in an optical microscope, you would see one tiny area in focus, and then the rest would be a blur. Even at relatively low magnification, your depth of field is no more than a few micrometers. This is just an inherent physical limitation of optics. Optical microscopes use lenses to focus on a spot, then you put the sample in that spot. If you think of the light going into the lens as a [cone]( URL_0 ), the only part that will be in focus is near the point of the cone. As the magnification increases, the cone gets wider and shorter, so the depth of field gets smaller. Some more expensive microscopes with motorized sample stages can take multiple images with the sample at different heights to get different parts in focus and then combine the images in software, but even this is pretty limited and doesn't always work. But scanning electron microscopes don't work like optical microscopes. SEMs use electromagnets to form a narrow beam of electrons. Then the beam is scanned over the sample and the image is generated by measuring the electrons scattered during the interaction. Think of taking a needle and poking it straight down at points on a grid and measuring how far down you get at each point (it's not actually measuring the height, but that's close enough for this discussion). The magnification is increased by just scanning a smaller area and displaying it on the same size image. The beam is still slightly cone-shaped, but it's far more narrow than the light in an optical lens. So instead of your depth of field being micrometers, now it can be as high as millimeters. [This image]( URL_1 ) shows the same object at the same magnification in an optical microscope and a SEM."
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7uhs6r | Why don’t we harvest spider silk if it’s so strong? | Technology | explainlikeimfive | {
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"This is going to sound crazy but.. There's this particular farm where they inject goats with spider DNA. This causes their milk to produce silky web after processing. Let me find a link because I sound like I'm taking crazy pills. URL_0",
"Spiders are cannibalistic, so they eat each other when placed close together. This means you need a lot of space. Also, each spider makes very little silk, so you would need hundreds of them to get a single gram of silk. Also, the silk that is the strongest would be the dragline silk made by orb weaver spiders (the ones that spin webs), but they also make around 6 other kinds of weaker silk, so you can't just collect their webs, you have to [strap them down and manually extract the correct type of silk]( URL_0 ). Because of all that hassle, [only one article of clothing has ever been created in modern times using pure spider silk extracted from spiders]( URL_2 ), and that took several years and over a million spiders to make. Because of all that, it is prohibitively expensive and time consuming to extract the silk from the spiders themselves. Instead, researchers and companies have been genetically altering other organisms to create spider silk instead. The most famous of which would be the genetically altered [spider goats]( URL_1 ) that make the proteins in their milk, but there are also genetically altered plants, bacteria, yeast, and silkworms used by various organizations to try to make cheaper clothing from their spider silks. Let me know if you would like more details on them, I can elaborate if you are curious.",
"Because it is super hard. You can't just farm spiders like you would farm for example bees. [Here is a picture of a piece of cloth made from spider silk]( URL_0 ) It is the largest spider silk cloth ever created and it took years to make, because any individual spider only produces so much silk. this literally took millions of spiders to produce that much silk and years of people wandering around harvesting the spider silk strands. The only way to hope for a production of this stuff on an industrial scale would be genetic engineering and trying to get some other organism that is much easier to handle to produce the same sort of proteins in bulk. There are some attempts along these lines like goats making spider silk proteins in their udders, but nothing that can actually be used."
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7uj3zd | Why did putting toothpaste on scratched discs back in the day work? | Okay, so back when I was a kid, when the PlayStation 1 was around, whenever a disc stopped working because of scratches my mum would always say put some toothpaste on it, wipe it down and try again.... well from the numerous times I tried it, it worked 100% of the time... also in the PS2 days... worked every time. Well now I'm older I've heard many people say its what they used to do too, me thinking it was only a trick my mum knew.... What is the reason it worked? It helped me out far too many times to be a coincidence... | Technology | explainlikeimfive | {
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"Its a very mild abrasive. So in short it can polish the scratches on the disk making it slightly smoother and the laser able to read it again."
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7ujx0q | Why does a phone camera flash twice before actually taking the picture? | Technology | explainlikeimfive | {
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"> When you press the shutter release, aTTL flash will fire a pre-flash before the actual shot, the camera will then measure the pre-flash with the ambient light level to calculate the power needed in the actual flash for the shot. Basically what you're seeing is a preflash. The camera uses that to measure how much power the actual flash requires.",
"The reply by lonex420 is correct, but there is an additional reason you'll see a double flash on many cameras; red eye reduction. The first flash will attempt to constrict the pupil (make the dark part of your eye smaller), so less light from the second flash will bounce off the back of your eye, which can cause the red eye effect you see so often in photos.",
"It has a secondary effect beyond measuring distance. Taking a pic in low light situations of people this quick flash causes your pupil to contract. If not the flash will bounce off the pupil giving you off a red or white reflection from them This why older photos of faces, pre 2000?, look that way. This has been a feature in SLR And DSLR flashes for a while now.",
"Metering, primarily, but you probably can't see that flash. The one you see is the \"red eye reduction\" flash as described. Turn the feature off on your camera and see if you can detect the very quick strobe pre-exposure, that's the metering flash where the camera uses the light meter to adjust how much it's gotta ramp up the power for the actual photo."
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7uk9kh | Why is a computer with 2 or 4 fast processors better than one with 100 or 1000 slow ones? | EDIT: Thanks for the answers. I learned that GPUs *are* many, many specialized processors. | Technology | explainlikeimfive | {
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"It depends on your needs. If your task can be split up into many smaller parts and processed without care of other pieces, then you can use 10000 cheaper smaller CPUs. This is the basis of distributed computing.",
"Same reason nine women can't make a baby in one month. Some tasks are highly serial in nature, and can't be divided up well. And even when they can, it often requires a very different approach and is not something you can switch to on the fly. If you wanted to get 100 things done as fast as possible, 100 slow processors would be the way to go. But if you needed 2 things done quickly, 2 good processes is often going to be the best way to go. You also see diminishing returns. 2 processors are *at best* twice as fast as one but usually are not. You lose time coordinating the processors, and often one has to wait on the other. The more processors you have to juggle, the worse it gets. In some cases, more processors can actually be slower.",
"Programs are mostly written in procedural languages: do A, then do B, then do C, ... . Programs written in this form are most efficiently executed in one super-fast processor. However, we haven't been able to make processors faster for about a decade. Instead we try to make them more efficient by branch prediction, speculative execution, and other \"tricks\". There is a point of diminishing returns for these tricks, and that's why computers don't seem to be getting faster in obvious steps any more. Instead operating systems are doing more parallel things, like listening to your voice commands, to make new computers seem cooler even if they aren't faster. Th bottom line, fast processors are very fast, for most things. Many processors requires a different type of program. That's why some games work a lot faster when you get a new video card, even though you have the same old processor. Video cards have parallel hardware, though it's more 100 simple processors than 100 slow ones. Video code is programmed in very different ways to take advantage of this parallel execution. As a result new video cards do seem a lot faster than the ones from last year. They are less general, but they can be made faster by adding more processors.",
"Couple of reasons. One: it's hard for humans to write software that can really take advantage of lots of CPUs. Two: there's a thing in computer science called \"context switching\". Basically, if you've got one CPU working on a problem, but then want a second one to work on the same problem, you've got to move all the data over to it. This takes time, so it ends up slowing things down.",
"Many (slow) cores are only useful if the workload can be easily divided across these cores. Consumer pc's need to be responsive to user input, which is not really parallellizable across multiple cores. So having a few super fast cores gives a much better user experience. In servers you can already see that different users get their own thread, and server cpus often have 20+ cores and threads. If you go to pure calculation work, that's very easy to divide over multiple cores, and that's what GPUs do."
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7ukktz | Why does FM radio sound better than AM? | Technology | explainlikeimfive | {
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"FM and AM manipulate radio waves in different ways (frequency versus amplitude) to encode the sound being transmitted. Ultimately, though, each station on FM radio has six times the bandwidth as AM. More bandwidth means more nuanced sounds are possible. Think of it like drawing with 48 colors versus only 8 colors. Plus, because of how FM works, it’s less susceptible to interference than AM, so you’re also generally getting better clarity to begin with. Edit: several people have asked questions about why FM/AM can't occupy other bands, e.g. move FM lower to increase its range. [Here is a cool chart of the US' current radio frequency allocation]( URL_0 ). There's other reasons, but one big reason we can't just move the bands around is that nearly every sliver of wavelength is already being used or reserved for something else.",
"Think of radio waves as being light emitted from a flashlight. Now the AM flashlight, Amplitude Modulation, is basically a white flashlight that changes in intensity or brightness to transmit the signal. An FM flashlight, Frequency Modulation, is a flashlight that always has the same brightness and intensity, but it changes color to transmit the signal.",
"There are some reasonable answers here, but none of them capture the essential reason. They all talk about the difference between AM and FM, but not why FM sounds better. Here's an ELI5: Commercial FM radio sounds better because it gets more of the radio spectrum. The reason it does is an accident of history. When a transmitter transmits radio waves, they go, well, everywhere. It works by shaking electricity up and down in a rod (an antenna), and that sends out waves at a particular pitch. If you want to think about it like sound, think of a tuning fork in a room, singing out at a particular pitch by moving air up and down. Receivers contain tunable tuning forks that shake up and down in response to the waves that hit them. Radio receivers then have to *decode* the shaking to create a signal. AM radios measure how \"loud\" (strong) the incoming waves are, and use that strength to figure out where to place the speaker cone. The transmitter makes its wave signal stronger and weaker very quickly, and that moves your speaker in and out very quickly, making sound. FM radios measure the pitch of the incoming waves. The transmitter adjusts its main tone slightly higher pitched, then lower again, and like that. That makes the receiver move its speaker cone back and forth, and that makes sound. So far so good, right? Well, if there is more than one radio station around (hint: there are hundreds), they all work at slightly different pitches. You adjust your receiver so it only resonates to one particular pitch, and then only one station gets received. There's a whole branch of the government that sorts out whose radio transmitters are allowed to use which pitch (frequency). Each station gets a range of radio spectrum it's allowed to use. So here's the deal. The lower the pitch, the less information there is in the signal! Huh? Well, if you have more than one radio station, you can't cram them too close together in pitch. If the main pitches (the big kids call them \"carrier frequencies\") of two different radio stations are too close to each other, then receivers can't tell the two stations apart, and the sound that comes out of each receiver will be a mix of the two stations. So you have to separate the radio stations' carrier frequencies. The amount you have to separate them in pitch is about four times the number of times per second your speaker cone has to move. So if you want to transmit high pitched sound at, say, 10,000 vibrations per second, you have to keep your stations more than about 40,000 vibrations per second apart in pitch. AM radios transmit between 600,000 and 1,600,000 wave fronts per second, which limits the number of stations you can fit in the radio band. The difference between those two numbers is about a million vibrations per second, so you can fit about 25 stations into the band if everyone wants to broadcast moderately high fidelity sound. FM radios transmit at about 100,000,000 (100 million) wave fronts per second. The band goes from 88 million to 108 million wave fronts per second. The difference between those numbers is 20 million vibrations per second, so the FM band carries 20 times as much information in total as the AM band does. (thanks, /u/zed857!) Instead of adding more stations (you could fit nearly 400 AM radio stations into the FM band!) we cut up the band into larger chunks. Since each station can transmit over a band 15 times wider than an AM station, it can send 15 times more information into your receiver. The receivers use that in two ways: (1) with FM coding, which reduces noise; and (2) to transmit stereo (which uses twice as much of the radio spectrum as mono) and higher frequency sound (which doublesthe spectrum usage again: AM is actually limited at something like 7.5 kHz, and FM goes to 15 kHz). AM radio stations generally sound sort of washed-out and flat, because the highest pitch they can transmit is limited by the rules for radio transmission! It's only about 7,500 cycles per second, which is not quite 4 octaves above middle C on the piano. AM stations literally aren't allowed to transmit higher pitches than that. FM radio stations have clearer sound because they can transmit higher pitches (like the difference between a telephone and a CD), and also because they can use even more of the radio spectrum to reduce the amount of background noise in your receiver. AM came first because it's easier to make an electrical circuit that works a million times a second, than one that works at 100 million times a second. Down in what we now call the AM band, there's just not a lot of room and technology like FM doesn't make much sense. The whole AM band could only support about 5 FM radio stations operating at the same time. When radios that could operate at 100 million times a second became common, everyone settled on the FM standard instead of using the same AM technique that was useful earlier -- because there's plenty of \"room\" up there at 100 million cycles per second. If an AM station had the same bandwidth as an FM station, it could transmit sound just as clear as FM(!) But AM is more susceptible to some kinds of interference (like lightning or electric motors) -- so FM was the natural choice.",
"Explained by /[u/harpyranchers](/user/harpyranchers) here: [ URL_0 ]( URL_1 ) \"If you can imagine instead of a radio tower there is a giant lightbulb. This is essentially the same thing electromagnetic energy but instead of being in the radio part of the spectrum it is in the light part of the spectrum. With the AM \\(amplitude modulation\\) lightbulb the signal would be varied by adjusting the brightness of the light. With the FM\\(frequency modulation\\) the light would change in color to produce a signal. If you were trying to see this signal through static, say a bunch of trees it was be much easier to see what color was coming through than how bright the light was.\" and the wonderful first comment underneath that, from /[u/TheRealBigLou](/user/TheRealBigLou) \"At first I thought this was more of a metaphor but didn't really explain AM/FM. But then I realized that with visible light, amplitude IS brightness and frequency IS color. This is brilliant!\"",
"Here is a [visual aid]( URL_0 ) on the difference between AM and FM radio waves.",
"To explain it you have to know what AM and FM stand for. AM is amplitude modulation and FM is frequency modulation. AM basically encodes the audio into the strength of the signal to play the audio, any thing that causes that to change will cause distortion from what was intended. FM on the other hand isn't dependent on that instead encoding it within the frequency, so it is a lot less susceptible to distortioin. That is the overly simplified ELI5 version of why.",
"AM uses the loudness of the frequency it's transmitted on to transport the sound. FM uses a changing frequency to transport the sound. Any noise on a frequency will interfere with the loudness of AM but will most of the time not interfere with FM.",
"Some of the answers here have focused on the fact that FM has more bandwidth than AM. This is true, but it's not the whole picture. FM stands for Frequency Modulation. The frequency you tune on a radio is the *carrier*. Signals are *modulated* onto the carrier. FM modulates the signal onto the carrier by changing the frequency of the carrier slightly from its nominal value. In order to detect an FM signal, the receiver has to \"look\" at the carrier, figure out how far it is from its nominal value, and create a value based on that. Millions of these numbers create a waveform which is the original signal--the music that was played at the station. AM stands for Amplitude Modulation. The carrier wave is simply louder or softer to reflect the signal. The receiver merely tunes to the carrier \"averages\" it to reconstruct the signal. OK, now consider what happens when interference is introduced. In FM, a change in the amplitude of the carrier due to interference has almost no impact on the signal. Take a thunderstorm, for example. Lightning throws a broad spectrum of EM into the atmosphere, which plays havoc with AM because some of that EM is at the same frequency as the station. Because any amplitude changes in the carrier represent signal, you hear lightning on AM. The lightning is still putting signal in the FM band, band but you don't hear it because adding a momentary pulse of 100 MHz isn't the same thing as creating a slight variation in the 100 MHz carrier to which you're tuned. When FM does have interference on it, it's slight variations in frequency. It turns out that the human ear is less sensitive to subtle variations in frequency than it is to sudden shifts in amplitude. To make it short, FM doesn't simply have more bandwidth. It's an inherently more robust way to transmit audio for human ears. Where AM shined was in the old analog TV signals. The audio was FM, but the video was mostly AM \\(not sure how the sync was transmitted\\). The result was that when TV signals were weak, they were \"snowy\" but still watchable. FM video would have made analog TV receivers unnecessarily complicated, and weak signals probably would have had more of a sudden drop-out effect like you get with weak FM radio stations.",
"There is a nice write up on Wikipedia [here]( URL_0 ) about how AM and FM developed and how FM differs from AM. The main point that answers your question is that AM radio uses 10 kilohertz of bandwidth for the signal and FM radio uses 15 kilohertz of bandwidth. The human ear can hear sound over a wider range of frequencies than either format can transmit. So both formats are actually deleting some of what we can hear but FM deletes less and thus provides a better sound. To use a similar analogy as other users. If I had a picture with 40 colors: a CD would let you see all 40 colors, FM would let you see 15, and AM would let me you 10. Of course not all colors are necessarily equally important. How many shades of mauve do you really need? So FM can sound good enough for most people.",
"It was greatly explained in this thread by /u/harpyranchers here: URL_0",
"Essentially 2 reasons The Traditional AM band, before the X band is added is just over 1MHz wide. 1) AM stations are spaced 10 Khz apart in the Western Hemisphere, 9Khz apart in the rest of the world Any time you mix two frequencies together you get 4 our, the 2 original the sum of the two and the difference of the 2 This means that if you are in full AM or Full FM as opposed to Single Side Band Suppressed carrier, on a 10kHz channel you can only get 5 kHz of audio bandwidth In 9Khz areas, it's 4.5Khz audio. While that does not sound so bad for spoken word it is not really enough for music to sound decent. The FM band in most of the world 88-108 Mhz is actually 20 MHZ wide, and each station has 100Khz for it's use. The way FM works it ends up with about 15 kHz of audio bandwidth. 3 times that of AM, and there is more bandwidth left That bandwidth is used in several ways One way is to do compatible stereo. Meaning that a mono radio will produce a mixed down mono sound and a stereo radio will produce stereo sound on the same station provided that the station has it's stereo encoder turned on Here is where the single side band comes in The Main channel is L+R or mixed down Mono there is in an unused part of the channel at 42kHz a signal that is L-R the left channel only. From this your stereo radio figures out R-L the right channel, that L-R signal is single side band so it does not affect the other side of the carrier leaving that for other things At 19Khz there is a narrow signal known as a \"Pilot\" The radio is designed to never pass that signal to the audio section. What it DOES do is essentially tell the radio when the broadcast is in stereo so it can light the stereo light and turn on it's stereo decoder circuit. Because of the wider bandwidth of the transmission the transmitter radiates the same power but does not produce quite the signal strength of a mono transmission. Another reason why the station may not want to broadcast in stereo is because the signal-to-noise ratio is not quite as good that way.The radio itself simply needs more signal to decode the stereo signal with any success. This is WHY the modulation on the stereo pilot signal is purposely so low, The radio is SUPPOSED TO revert back to mono mode when it can't get a strong enough signal for viable stereo. This is all 1960s technology. In the 1970s and 80s the stations were able to make improvements in their signals in another way Until then all transmitter antennas were either horizontal polarity or vertical polarity. In FM where wave lengths are all around 3 meters either was viable On AM where wavelengths range from about 600 meters to about 180 meters only vertical is practical Vertical polarization only actually discriminates in favor of car radios and portables and against the antennas of most stereos Horizontal polarization actually sounds a little better because most sources of static are vertically polarized. Circular polarization which is both vertical and horizontal at the same time was developed in the 1970s and deployed throughout the 1970s and 80s It DOES help with signal intensity and gives it fewer \"holes.\" Another feature developed by the radio manufacturers around the same time and deployed mainly on car radios but occasionally some higher end portables is one that actually varies the radio's own receiving bandwidth by a couple of Khz as you drive around and the signal strength varies to keep the signal as strong as possible. That's why you may hear variances in audio quality as you drive around. Another reason is the radio circuits themselves. The detector is the circuit inside the radio that actually separates the audio intelligence from the radio frequency carrier. It still rings true today that to build a good radio start with a good detector. Cut corners on the detector if you want to build a piece of shit! Because of the fundamental design of the different detectors used in Am and FM FM detectors employ what is known as the \"capture principal' whereby when there are two signals heard on the same frequency the detector will tend to \"lock in\" on the stronger signal and completely exclude the other At one time this pretty much insured that FM had almost no interference. Now especially up and down the two coasts ant through the Great Lakes region The FCC is trying harder and harder to essentially pack 5 pounds of shit into a 4 pound can No station is really interference free any more. As a result it's common to drive around and hear a car radio jumping from one station on a given frequency to the next. When that happens what is REALLY going on is that the two stations are so close in signal strength that the radio can't tell which is the stronger and it keeps bouncing from one to the other trying to lock on but unable to ever do so. Another problem with AM audio quality is that radio manufacturers know their customers would rather pay for good FM sound will build a decent FM stereo radio and stick a crap house AM receiver in it",
"Explained to a 5 year old. AM and FM are like two different straw sizes. More sound comes through the FM bandwidth, which basically is like a thicker straw. If you were to drink juice through a really thin straw, it would come out slowly and you wouldn’t taste it as well as drinking it through a McDonald’s straw, which is thicker and allows much more juice to be pulled through the straw. AM is narrow bandwidth, a narrow straw. FM is wider bandwidth, a much thicker straw.",
"Can't believe no one has mentioned the main issue: AM has a dynamic range of about 30 DB max and in the real world of talk radio, it's more like 15 db. By design, it is compressed all to shit to keep from over-modulating the transmitter and sounds just as terrible as you would expect FM, otoh, has a dynamic range of around 25-30 db in practice with a theoretical max of around 50 db. Still highly compressed compared to \"raw\" audio, but lively enough to still sound pretty good. For comparison, the range of a vinyl record is around 40-50 db in practice and 70 db theoretical. CD, DVD, and other digital formats can approach 100 DB",
"I'd also add that the \"locking\" of the FM detector onto the FM carrier wave affects the noise characteristics of the transmission. Essentially, in FM, the receiver can either detect the FM carrier peak, or it can't. As you move out of range of the transmitter, you move from a situation in which your station is the largest peak in your part of the frequency spectrum, to one in which it is sometimes overpowered by a separate noise peak. When this happens, the receiver suddenly locks onto a noise peak in the frequency spectrum. This often happens intermittently, causing a very irritating kind of noise in the recovered audio. In AM, the detector continually picks up noise along with the signal. As the signal gets weaker, the noise gradually begins to drown it out, causing a slow deterioration in quality."
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7ukmtg | Why video games cost so much to create? | Technology | explainlikeimfive | {
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"Licenses for the engines and other assets. Many designers, artists, modelers, riggers, testers, etc. A building for everyone to work in. And increasing demand for more features, better graphics, etc."
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7uktvd | Why does YouTube not let me rewind ads? | Technology | explainlikeimfive | {
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"If you could use the regular seek bar, most people would skip to the end of the ad (never mind the Skip Ad *button*; it's a different function, and it's not always present). YouTube doesn't want you to do this. It was easier to disable user control of the seek bar altogether rather than create one that allowed going back but not forward.",
"I don’t know, but I would say it’s related to the restriction of fast-forwarding the ads so you can’t skip them faster. If you want to replay an ad, almost every time there’s a link to the video itself."
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7ukwjw | Why don’t the speakers at loud concerts cause feedback in the singer’s mic? | Technology | explainlikeimfive | {
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"Firstly, because there’s a sound engineer making sure it doesn’t. Mics that people sing into live at a loud venue are directional: they pick up sound way more from the direction they’re pointed. The concert speakers are positioned in front of the singer, facing outward. Before the concert, they determined how much gain (amplification) the mic gets and how loud it can be without causing feedback. Often they’re turned down to stop feedback, and in live venues have to sing pretty loud. It’s part of why album recordings sound better, among other things. In a quiet room at a quieter volume, we all sing better.",
"First of all, depending on a combination of room acoustics, mic/speaker placement and frequency responses of the mics and speakers; certain frequencies are more prone to feedback than others. We use a a few techniques and best practises to minimise the risk of feedback. These include: - Choosing appropriate microphones with narrower pickup patterns to minimise bleed from other sources reaching the mic as well as positioning the stage monitors as best we can so that they are firing into the mic's least sensitive spot. - We try and keep the stage volume as low as possible so that the musicians can hear what they need to hear as clearly as possible. The theory being that if you have a noisy stage, the musician will keep asking for more level in their monitor, increasing the risk of feedback because they can't hear themselves over the other noise. - We work with the artist to improve mic technique, for example, encouraging them to stand close to the mic and sing louder rather than mumbling. These things allow us to minimise the amount of gain applied to the mic and therefore minimising the risk of feedback. - Before soundcheck, we ring out stage monitors (sometimes PA too if it's a small venue). This consists of slowly increasing the gain on the mic to induce feedback and systematically using EQ to reduce the level of problematic frequencies until we can achieve a decent level of headroom without any feedback present. Hope this clears it up for you! This is the first ELI5 I've actually been somewhat knowledgeable about. It's a lot harder than I thought to ELI5!"
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7ul8ww | How do doctors amputate limbs? | Do they cut off and cauterize a little bit at a time or do they just chop that bitch off and do it all at once? | Technology | explainlikeimfive | {
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"Kind of depends on the type/level of the amputation. Typically you identify the major nerves and vascular structures and tie them off, followed by cutting all the soft tissue with the bone being last.",
"Yeah! I can finally answer something. First, you make skin flaps to make sure that you can cover the wound. Then, you cut down to the bone. Usually, you clamp the vessels as you go and then tie them off at the end. You also try to cut out of as much nerve as possible to avoid neuromas (not sure if this actually works). At the bone, you can use a bone cutter, but we usually just used a Gigli saw. It’s a piece of razor wire that you hook up to handles and then saw back and forth. Finally, you sew it all back together again.",
"how would they chop it off? battle axe?"
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7umce6 | With as far as technology has come, why can't we stop robocall telemarketers and number spoofing? | Technology | explainlikeimfive | {
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"As far as technology has come, they keep figuring out new ways to do it! Cat and mouse, cat and mouse.",
"The telephone network was built on a premise that the system where the call originated is outside your local phone company's control so the phone company has to accept the call Otherwise long distance and international calls would never work. The cost of revamping the system prevents it from happening. The main issue with spammer and robocallers is that the identity of the caller is not registered and therefore cannot by blocked by registration. In order to enforce registration, you would have to have a global consensus on a new phone registration system and the decades it would take to build that."
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7ument | How do planes avoid collisions above the Atlantic where there is no radar? | Technology | explainlikeimfive | {
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"There are airplane “highways” usually separated by 10 000 ft. East you fly odd (ie 30 000ft) and west you fly even(ie 40 000ft)",
"planes have their own radar plus the pilots have windows and, as others point out, there are standard flight lanes/rules you follow to prevent collisions",
"Any plane that has a 10 person capacity or greater is required to have what's called a Traffic Alert and Collision System which does warn pilots of nearby air traffic and sounds an alarm when a plane is within a certain distance and on a collision course. You can read more about it here: URL_0"
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7uorxy | How does FM Synthesis work (e.g. sound chips like the Yamaha YM3812) | Technology | explainlikeimfive | {
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"you may like this video - URL_0 FM Synthesis in the context of the YM3812 had a few available voice channels for oscillators. The samples produced are eventually fed into a digital analog converter that creates a stream of voltage varying very quickly into an amplifier that makes sounds come out of your speakers."
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7ur20v | How does "Log in with Facebook/Google" work? | Technology | explainlikeimfive | {
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"It doesn't. You log in with Google and Google acts as a trusted individual to the website, vouching for your identity. In simplified terms this is what happens: 1. You press \"Log in with Google\". 2. The website goes to Google, and says \"Hey, I have a person who wants to log in with his Google account, that cool with you?\" 3. Google says \"Yes, but give him a connection to me\". 4. The website shows you the google login page, directly connecting you to google, but won't see what you're doing there. 5. You log in. 6. Google goes back to the website and says \"The person you sent to me successfully logged in. Grant him access to his account.\" 7. The website grants the user a token from Google, a string with some random key, and says \"Ok, you're good to go. Whenever you come back to me just show me this token and I know you've logged in already.\" 8. You browse the website as normal until the token expires or you log out, in which case go back to 1."
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7urmbh | How does a mobile phone "try" to find a signal? | Most of us have had a phone eat up a ton of battery when we were in an area with bad coverage because the device was working to find a signal. Isn't the antenna on it just passively receiving available cell signal? Could you make a stereo use more power by having it "try" to find a better signal on a radio station? | Technology | explainlikeimfive | {
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"A mobile phone generally does a couple of things when it is just kinda lounging around: 1. It has to tell the world where it is - this is so that the tower can route incoming calls to the phone. This is done with an amount of power based on its current \"status\" of connection. So...power consumption here is _variable_, based on signal strength. 2. When it doesn't have a connection, it will attempt to do so. This \"find a connection\" signal is sent out at _full power_. It does this after anytime it's lost its connection to a cell. So...no, it's not just listening passively - it's initiating and maintaining conversations with cells, so to speak.",
"Most digital traffic relies on a handshake to create a connection. This hand shake has multiple parts but let's simplify it. Tower: I am a tower at 900mhz for Verizon Cell: I see you tower at 900mhz, I am cell123 Tower: I see you cell123 at 900mhz, can you use Band7 Cell: I can use Band7 Tower: Cell123 Use Band7 Cell: Using Band 7 now Tower: Cell123 send your phone data. Cell123: (Chunk of data) Tower: (checks with network) okay cell123 you are connected, here is your call routing information, data rate, and IP addresses. Cell: I am connected When you are searching for a signal your phone is picking up a lot of towers usually that are to far away to do a good handshake. It might get some data but most is too weak to make it. Once connected the phone has an existing relationship with the tower and only transmits as needed. When there is no connection it has to transmit constantly to build a connection. There is a lot more to Cellular connections but that is my basic understanding of it. Think of it a bit like the energy used to find an unknown person in a crowd versus just keeping an eye on a person in a crowd you already know.",
"Every now and then, your mobile phone hits a tennis ball out into the sunset. It keeps on hitting tennis balls into the sunset, until something over the horizon sends the tennis ball back and the ball hits your phone in the face. When your phone gets hit back in the face with the tennis ball, it knows that it has a \"signal\".",
"Side note - difference between 2G and 3G phones - when a 2G phone turns on and starts looking for a network, it broadcasts at full power, and the network tells it to dial back power to the lowest necessary. 3G phones “start quiet” and ramp up their power output to appropriate levels, to preserve battery. But like other have said, your handset is always trying to handshake with its network, and if it’s moving, it’s constantly reporting the signal strength it has to surrounding cells, so the network can do useful things like hand your call off between cells as you head down the road. Mobile, and especially the air interface, is outright voodoo black magic.",
"Battery life, as everyone knows, is extremely important for cell phones, so manufacturers do everything they can to reduce the power consumption. The phone has to 'listen' to the radio to see if a call or text message is coming in. When the phone handset has 'found' a tower, it's synced to a specific frequency and receives a very precise time signal from the tower. The tower (and network) tell the phone there's nothing for it. So, go to sleep for 1/2 second and then wake up and listen for 1/10 second. If there's anything for that phone it will only be sent during that 1/10 second. So the phone can turn its radio off and sleep 8/10 of the time and still receive a call or text within a second. If the phone hasn't 'heard' a tower and isn't synced to a time slot, it has to listen all the time. And it's constantly shifting between multiple frequency bands. So it is 'awake' all the time and can't sleep. Because it can't sleep, it uses the battery all the time, and runs down much faster. Here's a (non-ELI5) Wiki on Time Division Multiplexing: URL_0",
"Hey u/_snacknuts. I haven't seen anyone address the stereo part - You can use an amplified antennae to boost the signal. You can also just get a bigger antennae. But you don't \"find\" a better signal with it, it'll just be using the existing signal as it is."
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7utkmy | Why some computer programs output text like "1 connection(s)" even though they clearly know the count? | On multiple occasions, I have noticed Windows report numeric information along with the plural form of the accompanying noun in parenthesis. If the actual count is known, why can't the developers make the extra effort to actually compute which of the two forms (singular or plural) they should output? | Technology | explainlikeimfive | {
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"Partly it's laziness on the part of the developer, but it's also because getting plurals correct internationally is a lot of work. Let's say your program needs to be translated into 20 languages. In English we have one form for one item (singular) and another form for zero, two or more (plural). But other languages don't always work that way! Some languages have different forms for zero or two, or other complicated rules. So, software that puts a lot of effort into being very user-friendly and customized for every language will go to the effort to do it right. Software that just needs to work will skip that extra effort and do it the simple way. It's uglier but it's clear.",
"A few reasons. 1. While checking for plurality is computationally incredibly cheap, it is not free. If this is in log files that are constantly writing, you try to spend as little work calculating things that would just 'be nice'. 2. If an application is copied to different locales, the rules for pluralization may be different. Check out URL_0 for more info. 3. \"Hello < User > , we have recognized this issue and have created an item in our backlog to resolve this issue.\" \\*item rots in backlog for six years\\*",
"Fixing it adds extra clutter to the underlying code, which is most likely way over cluttered to begin with.",
"In a nutshell, we're lazy. Quick and dirty in php: echo \"$var connection(s)\"; Instead of: if($var = 1) { echo \"1 connection\"; } else { echo \"$var connections\"; }",
"u/dmazzoni has it. This is something called localization. I would wager the majority of software out there simply doesn't support anything other than their native locale. It's really a big hard problem for a small company to solve, and hard to justify chasing foreign markets. Europe especially is a hard market to target because you have so many small nations with possibly multiple languages. You're an English speaker, so you have a large and homogenous market from which to buy software. And if I were Dutch, I'd consider going after the English market as well, because it's big. Lots more money can be had there than in my native country. But I'm a native English speaker, what business do I have writing Portuguese translations, or Cantonese? My employer would have to pay for translators. And all text would go into locale tables, along with complicated scripts to express how the grammar is to change depending on available variables. Developers and companies can get it right, but it's really just not worth it. I'd rather develop a new feature that will sell more units than worry about plurality of a word that isn't going to give us any competitive edge."
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7uuiaf | Why does the glass on newer phones like the Pixel 2 and iPhone X feel soft to the touch? | Technology | explainlikeimfive | {
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"text": [
"The oleophobic coating. Maybe they use a higher quality coating. Every device has this coating. Its to prevent finger smudges."
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7uumf6 | What are vacuum tubes on amps? Do they actually do anything? | I've been looking around for a amp and everyone is recommending one with vacuum tubes. I'm confused if they do anything, or if they're just there to look cool. What do they do vs digital? How does it work? | Technology | explainlikeimfive | {
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"Vacuum tubes predate transistors, and act as amplifiers. Both work on the basic idea that a small current, your audio signal, can proportionately regulate a large current, from the wall outlet, for example. How they both achieve that are very different. Transistors, which everyone knows is how they make computers, were originally invented to be an amplifier. Vacuum tube amps and transistor amps are both analog devices. The analog vs. digital comes up in your recording and playback equipment. A record is analog, in that the signal is only as precise as the carving in the vinyl and the player's manufacture. Magnetic tape is also analog. Digital audio is produced by taking a measurement of the current generated by a microphone regularly over time. That's sampling and your sample rate. This analog signal off the mic is passed through an Analog to Digital converter, which is going to turn an analog sine waves into a number, the more bits an ADC has, the more accurate the representation of the original signal. These numeric values are fed into a Digital to Analog Converter, which reverses the process, and then that is piped through your amplifier. Unlike your record or tape, which the sound can change because the media physically wears out, or expands and contracts with temperature, a digital sample will be reproduced effectively exactly every single time, forever. Audiophiles like to think vacuum amplifiers have a \"warmer\" sound, which might be true, but what if you don't always want that? I think there are too many variables to make a comparison meaningful. Every piece of equipment, how they're wired, and the shape, material, and contents of your room are going to change how your audio sounds. If you compare a $1k vacuum amplifier to a $1k opamp in a double blind test, I wouldn't expect you to be able to discern a difference."
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7uuzpa | How are cars in Google Maps perfectly positioned and photographed when the Google Map car moves? | Technology | explainlikeimfive | {
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"You've seen photos from sporting events, right? Of athletes while they're moving? You just take the picture very quickly."
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7uvdti | in terms of video games, what exactly does AAA mean? | Technology | explainlikeimfive | {
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"It's a general term used to describe high budget games made by big name studios. For instance, the Mass Effect series, GTA, Red Dead Redemption, Call of Duty, etc. Typically people have higher expectations of these games because of the amount of money being invested in the project and advertising.",
"Triple A is mostly a marketing strategy and a word that means that a game has very high costs for developement and marketing and needs to be seen as a hit or miss investment, rather than a game that can go under and the publisher won't really care. The name itself is basically just borrowed from industries like the credit industries, where companies can get an AAA rating, for example for how likely they are to pay back loans. It has no gaming-specific meaning."
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7uvfvb | Cell phones connect with each other via wireless signals but how does a cell phone connect with a land line | Technology | explainlikeimfive | {
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"Cell phones actually connect with cell towers via wireless signals. Cell towers are tied into the land line infrastructure. For two cell phones to communicate, the call has to be routed over the land line to the nearest tower and then transmitted back to the other phone. With land lines, there's no transition back to wireless; it just gets connected directly.",
"> Cell phones connect with each other via wireless signals Not exactly. They aren't like walkie-talkies, connecting directly with each other. Cell phones connect through microwave transmissions to cellular towers which are connected to a ground-based network. This means if you call someone on a cell phone across the country your call will go a couple miles to a cell tower then go through cables on or under the ground to the closest tower and then across a few miles to their cell phone. Calling a land line then is just a simple as having that call routed to a ground line rather than another cell tower."
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7uw4a3 | Compared to talking in person, why can two people talk normally on the phone but video chatting is so awkward and interrupting each other? | Technology | explainlikeimfive | {
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"Body language might be a factor. When you are sitting face to face with a person, subtle clues about how they are feeling, or what they are intending to do may be more visible. For example, you may see and hear someone take a big inhale when they prepare to begin speaking, but on a webcam you may miss this detail."
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7v3l6v | The difference between UHD 4K, Super UHD 4K, Dolby vision, HDR. | I just bought an LG Super UHD 4K tv and when I watch Netflix it says it's playing in Dolby vision. What exactly is that and what does it mean in terms of my tv. Thank you | Technology | explainlikeimfive | {
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"UHD is a standard resolution of 3840x2160 pixels. This is the next step up from FHD (Full HD) which has a resolution of 1920x1080 pixels and HD which has a resolution of 1280x720 pixels. UHD has exactly four times the pixels per field as FHD and maintains the same 16:9 aspect ratio. UHD 4K is a marketing term used to distinguish the display from other \"4K\" display formats that use different field sizes and aspect ratios. HDR is a term used in video processing that has different meanings based on context but all relate to contrast. **High Dynamic Range Rendering** has been used in video games for more than a decade to more accurately reproduce reflections of bright lights without artificially brightening the whole scene. **High Dynamic Range Video** is a two part display requirement. First, the display must exceed specific peak brightness, darkness, and peak contrast ratio values. Second, the display must be capable of processing 10 bit per sample colour values. HDRR and HDRV are entirely distinct technologies. HDRR does not require an HDRV display and a standard display will look much better when HDRR is enabled. On the other hand, HDRV is useless if the source material is restricted to a standard dynamic range. Plasma Display Panels long ago met the darkness and contrast requirements but fell behind in peak brightness. LCDs met the brightness requirement but had terrible darkness and contrast. Only in recent years have LCDs been able to match the colour reproduction of PDPs that are considered obsolete. Moreover, 10 bit sampling was foreign to consumer devices until very recently. Historically, it's use has been restricted to professional devices. Dolby Vision is a mastering format designed to facilitate accurate encoding and reproduction of colour and brightness by the display. Dolby Vision compatible displays have greater knowledge of how the master was *intended* to look and can use that information to reproduce it as accurately as possible.",
"UHD - means \"ultra HD\" its a nonsense marketing term for 4K and pretty antiquated. 4K means 4K resolution Super UHD - is a nonsense term, the \"super\" doesn't mean anything its just a tv line, like a Toyota \"Corolla\". These aren't even the top end TVs they make. Complete non-meaning in any way. HDR: this is an image format. Its somewhat complimentary to 4K. 4K is all about resolution, HDR is saying it has a better way to display colors. HDR makes stuff really pop, and will kinda be a bigger deal than 4K, but adoption is even slower in content as you need an HDR tv to see HDR, and its really just starting to be put into mass market tv sets. Dolby Vision: There are a few different ways to implement HDR, Dolby vision is the newest one being widely adopted and seems to be becoming an industry standard going forward. Further, if you're buying a TV now, and can afford it, buying a 4K HDR TV capable of Dolby Vision is pretty much the baseline standard. Edit: To the people complaining that UHD has technical meaning, thats not wrong, but you're getting sold on what it means for tv. Its specifically written into TV names as marketing jargon (not technical jargon) to confuse consumers. Again, its complete nonsense... the marketing departments at Samsung, etc. are clearing doing their job well to draw such a response.",
"One distinction missing in this thread so far is that Dolby Vision uses dynamic metadata whereas HDR10 uses static metadata. Metadata refers to information carried with the video stream to indicate (for example) the maximum light level of any single pixel and the maximum average light level of all 8 megapixels in a complete frame of UHD video. These values are used by the display when decoding the video stream and rendering the frame images. Dynamic metadata (Dolby Vision) means that you can have different light parameters for different scenes within the program, whereas static metadata (HDR10) means you need a single set of parameters that will be used for the entire program. You should get greater dynamic range in Dolby Vision if the program includes both dark scenes and bright scenes. But it is more difficult to decode (requires Dolby proprietary chip set) so HDR10 is more commonly available.",
"There's some good explains already given, but also still incorrect information in those answers. There's some really clear explanations of these terms in Rtings. 4K and UHD URL_1 HDR URL_2 HDR10 Vs Dolby Vision URL_3 QLED, OLED and LCD URL_0 (Note I've nothing to do with Rtings, I just find their explains correct and clear)",
"Dolby Vision content is mastered in up to 12-bit colour depth, compared to 10-bit of HDR10. 12-bit color depth allows for over 68 billion colors, compared to just 1 billion with 10-bit. Dolby vision reads metadata embedded in the frames to adjust other display options such as brightness on the fly the way the director intended. Some additional somewhat unrelated info on resolutions: * UHD 4k: 3840x2160 @30fps 4:2:2 or 4:2:0 * True 4k: 4096x2160 @60fps 4:4:4 * 4:4:4 no color subsampling, full color * 4:2:2 or 4:2:0 colors aren't as rich * 30 frames per second will make movement more blurred, keep in mind most movies are shot at 24fps * 60 frames per second is good for gaming or sports, and movement is smoother and crisp",
"Other people have good explanations for the other terms, but this is what I tell people HDR: HDR is like Oxiclean for your TV. Brighter colors and darker darks.",
"Can anyone tell me why some of these formats make movies seem like they have that “live filming” or “soap opera-y” effect? Watching movies that seem so realistic feels very different. Is that intentional? I know it is subjective, but is that considered better?"
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7v63eq | How come when you put earphones in your nose and pop your ears you hear the music in your head? | With a question like this you may as well treat my like I'm 5 too, but I'm genuinely curious. If you keep your mouth closed and pop your ears if feels like the music is in your mind, why does it do this? | Technology | explainlikeimfive | {
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"Our hearing apparatus consists of the external ear (which is our floppy ear pinna and ear canal) and the ‘internally hidden’ middle ear, and internal ear. Normally, the sounds from outside is transmitted from the external ear then towards the eardrum into the middle ear, and lastly, towards external ear, where the sound energy is converted into electrical impulse which is then brought towards the brain, where it interprets the sound. However, in your case, the soundwaves from the earphones causes vibrations inside the your nose, which then can be transmitted through the skull, directly towards internal ear, where conversion process occurs. Sooo, basically it skips your ‘ear’. (This is also the basis for clinical examination for hearing problem) I hope this answers it!",
"Why would you do this in the first place?"
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7v6gog | How do airlines get your checked luggage on the right plane when there is a short layover? | I know they scan the barcode and that tells them what plane and stuff, but what is the process that happens that gets the bag from one plane to another, accurately and on time? And yes I know it’s not ALWAYS accurate. But it is very accurate. | Technology | explainlikeimfive | {
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"They usually sort it at the departing gate. They know which luggage needs to be taken out first. That information is sent to arrive airport. They also compartmentalize the bags. Ie, belt, terminal 1, terminal 2, etc. So this way, its easy to put the bags in correct cart and take it to correct place.",
"the bag comes off the arriving plane and is bar code scanned. the arriving airport systems know what the gate the connecting flight is. so the handlers just have to put it on a truck giong to that gate. bags that are for transfers can also loaded in last into the airplane cargo hold so they're near the airplane cargo door. those containers or bags are the first ones off",
"If you fly a lot you notice the flight to LA on Spirit airlines always leaves from gate A2 for example. Most connections you make are with the same airline. The guys handling the bags at a landing sort the bags. Most are headed to the local baggage pickup. Most of the remaining ones are headed to a gate close by. A carrier truck runs those over to the gate where a flight is headed to your destination. If you are changing carriers along your route you are usually told to wait for your checked bag at the gate where you arrive and gate check onto your next flight as baggage handlers can't go driving clear across the airport to find the gate and flight on another airline, but you can.",
"Depending on the airport, it’s a complex conveyor belt system that helps gets the bags from one area to another. Here’s a cool video of it. URL_0 Edit: spelling of words."
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7v8vr7 | Why does a pc have to be significantly more powerful than the console it tries to emulate? | Technology | explainlikeimfive | {
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"Quite simply, because you are adding another layer of abstraction to it. Imagine trying to unscrew a nut while holding the plyers with another pair of plyers. It is certainly possible, but you going to need a bigger amount of force to hold on to the plyers and move the nut.",
"Imagine you're trying to read a book in your native language. Easy right? Now imagine you're trying to read a book in another language, but you have a dictionary. So you have to look up every word. Take you a LOT longer right? You finish the task much slower. So to read the same speed as a natural speaker, you might need to be able to read, and search through the dictionary, ten times as fast, or more. That's emulation.",
"Because a PC is not built to understand commands from different consoles. Consoles have their own hardware architecture, and their own hardware commands. Consoles have been designed to streamline and run these commands as efficiently as possible. PC's however, run on a different hardware architecture. As a result, the emulator has to convert all these hardware commands into software instructions the processor can understand and run. With software overhead as well as the multiple instruction conversions that happen per second, it's clear that an emulator must be more powerful than the console it emulates",
"EDITED: So, my original response got zapped by the mod (and I've no interest in debating the merits of that, let's move on), so let's try again. To emulate means to equal or approach equality with. What makes console emulation hard is that your PC has to do it well enough to be acceptable (the game must look the same, say) and fast enough to play the same. Imagine your friend drew a picture with some colored pencils. Looks great right? Now your job is to take another sheet of paper, and, as quickly as you can, draw exactly the same picture. Same lines, same shades, same colors. Your pencils are mostly the same, so that at least gives you a leg up, but boy...it's gonna be hard isn't it? Now try doing that and being told you have to draw it as fast as your friend did the first time. Let's take a detour into the \"mostly the same\" clause. If the PC has key components that are identical to the console, that's like you have the same colored pencils. You say \"I need a thick dark orange \" and lo and behold, you have the perfect pencil to hand. This is like your PC running the same operating system on the same processor chip as the console. Life is looking sweet. But if the components differ, that's like you needing a thick dark orange but only having a thin pencil. You can get there, but it's gonna take more time. In PC terms this is like having a CPU that has different chip registers from your console. Or maybe you need orange but you only have red and a yellow. Your PC is missing some hardware feature of the console and it has to cobble together a solution in software to make it right. In short, when a PC emulates a console, you are asking it to do everything the console does, just as fast, but using its systems. It has to work harder to get it right.",
"The difference is a result of the time cost of emulating hardware registers (storage locations in the CPU and graphics for instructions) in software. The reason is **not**, as some have suggested, to do with translating between differing CPU architectures. In fact, the major console CPU's are using the same CPU architecture as your PC, which is the x86-64 (also known as x64, x86_64, AMD64 and Intel 64) architecture. However, the console processor is packaged in a tight configuration with the graphics bridge that we call *system* *on* *chip*. The exact configuration is secret (proprietary), but it can be reverse engineered and then mapped to your system, which is what the emulator does. Quick background knowledge: The speed of communication between active memory (RAM) to the computer's brain (CPU) is much slower than the speed of internal communication within the CPU (CPU to CPU) and also slower than CPU to graphics. These external communications are usually ten-times slower (an \"order of magnitude\" slower) than the equivalent internal communication would be. RAM to CPU can be even slower than that, but ten-times slower is a good estimate. On your console, your game disc has instructions that read-from and write within the CPU and graphics bridge. These instructions are interpreted very quickly, since they're CPU-internal for the console. On your PC emulator, however, the console's registers are being represented virtually in software, meaning that they're assigned locations in RAM by your operating system. So every time the game reads or writes from these virtualized registers, it takes roughly ten times as long as it would on the console. To account for the lag this would produce, your PC needs to be much speedier than your console needs to be (not necessarily ten times as fast, since most of your emulated gaming experience will not fit the the worst case scenario).",
"Playing games native to your PC or to your console is similar to reading a book in your native language, you’re only limited by your vocabulary and reading capabilities from understanding it (performance loss). Now imagine you want to read a book in language you don’t understand because your friends recommended it to you to read it. Before all that you need to learn the language (create the emulator) and learn it’s quirks and vocabulary (optimisation). Problem with all that is you are reading in a language you haven’t grew up with so you will hit into hiccups that will require you to stop and examine or reread them (graphical and performance issues). In the end you will be capable of getting over those obstacles but iťs an eternal pursuit for knowledge to understand that language, so you won’t understand it well in the end, but well enough to have fun while reading the book...",
"The SNES (for example) and the PC don't speak the same language so a program (emulator) stands between the game code and the PC that converts the game code to something the PC can understand. This extra step requires more speed from the PC than the SNES had.",
"Because the console has separate specific hardware for doing every element of the process. A main CPU, hardware for generating sound, video circuitry, etc etc, on which runs the main kernel which the game talks to. An emulator is purely software. In order for the original game software (a rom) to work properly with this software, it has to absolutely mimic the behaviour of the original system. So you have to simulate the CPU, simulate all the ancillary hardware, as well as the internal software. Because there's all that extra stuff to do, you need a more powerful computer.",
"Because your Nintendo only has to run the video game, whereas your computer has to simulate the Nintendo that runs the video game. The bare metal video game system becomes a program on a general-purpose computer. It takes resources to run a virtual machine on your actual machine because its hardware doesn't actually exist. It's the difference between cooking breakfast and building a robot to cook your breakfast.",
"For one computer to emulate a console (another computer), it must pretend to be the console and run the game as fast as the console does. It is very complicated and time consuming to pretend to be another computer, so it requires significantly more computing power to run the game in time. Less eli5, a console is hardware (the console) running software (the game). An emulator is hardware (the computer) running software (the emulator) pretending to be hardware (the console) running software (the game). All of the pretending takes a lot of time. Bonus, some consoles, especially older ones, have hardware flaws. Some games depend on those flaws to function. So, good emulators must deliberately have those flaws.",
"Okay ELI5... Imagine you want to solve a riddle. However, the text for this riddle is in French and you only speak English. Before you can even try to solve the riddle you need to translate it in English, which will take you some time, and only then can you then work on solving the logic portion of the riddle. It's a bit like that because the ROM your PC reads has computer opcodes meant for a machine that is different from your PC, so they need to be translated to something your PC understands first. Both the console and your PC are able to ADD two numbers, but they say it differently. But this analogy does not cover it all because it's not always only about translation: quite often the machine being emulated is capable of operations that your PC isn't (for example, because those are highly specialized operations that have been committed in hardware) and your PC can't just do a one to one translation for those but must rather run multiple of its own instructions to do the same thing. As an example, even though the emulated console has a different opcode for ADD then your PC, there is (mostly) an equivalent instruction. But, all the early consoles had specialized hardware for dealing with sprites allowing to display sprites on screen with very simple instructions, whereas PCs don't, so there is no \"natural\" translation for such operations.",
"Answers are good but this needs to be said. By powerful you think how much CPU cycles you can execute and maybe how many video texture or pixels you can push. However you're not just emulating the consoles CPU with your CPU you got to emulate the video hardware with your CPU and audio too if it uses specialize hardware. It isn't just copy/pasting the memory contents cause that'd be easy. On the NES in video memory it can represent one 8x8 tile (2 bits per pixel) using 16bytes of memory. To draw that on modern hardware you have to take the NES video memory, then translate it to 192 or 256 bytes (RGB or RGBA) then give it to your video hardware. PCs speak RGB not the specialized NES video memory. NES can't speak HDMI. It's stuff your CPU has to do and your CPU isn't even emulating the consoles CPU during this. There's also another problem. Games might take advantage of hardware timing which means you cant just translate the results you have to translate steps which is more work. For example the NES might be able to scroll the screen however it can not scroll the screen at two speeds [yet it has been done]( URL_0 ). The trick is by using some cartridge hardware (less common) or by using sprite 0 collision (which is built in to the NES) to trigger a hardware event. When the event happens the game pokes the video hardware to use a different background X axis which causes it to draw at a different location. To emulate the effect you can't just look at the video memory and draw it. You'd have to draw one or a few pixels, execute the CPU/hardware then draw the next pixel or next few pixels. It'd be easier to translate one video memory to another but you wouldn't get the effect. Without it the game will look wrong or the game won't work because it didn't receive important hardware events at when it was suppose to receive them. tl;dr: You don't use CPU to emulate CPU and video to push video memory, there's more to it.",
"Imagine your console is like a secretary. Your console dictates a memo out loud and the secretary types it. An emulator is like this: now the console is dictating a memo, but the memo is in English and your computer only understands Spanish. So the emulator translates the memo to Spanish and the secretary then types the translated memo. Only, your computer has to be both the secretary and the translator.",
"First, a console is just a computer. Second, your PC is also just a computer. So your PC essentially (for laymen’s sake) is working twice as hard... to run itself, and to run the other computer (the console, which is made of software when emulating it). Thus you need a PC significantly more powerful than JUST the console you are emulating for it to run smoothly. Ignore the long-winded answers that get technical. It’s really this simple on the surface.",
"Emulators need to work like the original. To take care of every tiny detail, the computer needs to do a lot of work. For example every bug, every undefined behavior etc. has to be exactly the same or you'll run into problems. So you have to take care of a lot of stuff that a normal computer doesn't have to care about. You can't really emulate anything modern because we have reached certain limits with some of the things. Processors aren't getting any faster for example, world record for the fastest production processor (overclocked) is from 2012. We have reached the speed limit of processors like a decade ago and since we've just made them do more stuff at a time and have multiple processors do stuff at the same time to improve performance and have them try to predict what you're about to do (which resulted in some hilarious bugs that have been in the news for the past month) etc. Memory isn't faster either, it's limited by pesky things such as speed of light and so on. Stuff we haven't even approached back in the 80's and 90's. Very sophisticated malware do this, they check for tiny bugs/undefined behavior in the CPU that doesn't occur in a virtual machine/emulator/sandbox so they know when someone is trying to dissect them or figure out what they do. What we do is we FAKE IT. Instead of emulating the whole thing, we just emulate the parts that matter so that programs/games work. You don't need to emulate the whole thing (except for fun), you only need to emulate a small portion of it to make the software compatible.",
"One reason is that there is some instructions that may not exists or are different. For example, if your console have a \"multiplication\" opcode, but the host pc do not, then it need to emulate it. Some instructions on the console may also be more optimised, so the same multiplication on the console could take 2 cycles while on the pc it could take 6 cycles (3 times slower in this case). Some console might also have a reverse order for the bit storage. PC use the same order as us, the most important bit on the left (or first). Like us, the thousands are before the units. But on some it's the reverse: least significant bit first. Want to store \"twenty five\"? A PC will store \"25\", while an old mac using the motorola cpu would store \"52\" (actually, 00011001 on pc, 10011000 on the old mac). This mean that it also need to swap it. Not only that, but the video card is custom made for them, and may not have the same functions as your. Same with the sound card. For example, I beleive the NES basically have this: channel 1, set to squarewave, play tone 440Hz. Channel 2, set to triangle, play tone 587Hz. (half a second later) stop channel 1, stop channel 2. and so on. On a pc, this need to be emulated. The sound card in a pc can NOT do that. All it can play is a sound sample. So you actually need to make a subprogram that will generate the waveform in real time (there is some ways to cheat however), then feed the data in real time to the sound card. Some video features may not be available on the pc too. The same need to be done: redo it in software instead of doing it in hardware. Of course, there is way to reduce the overhead, for example, if it use the wrong bit order then swap all of them in the code, and swap the related instructions too, like \"shift bit left\" become \"shift bit right\". This can be done before starting the game. Some other instructions can also be replaced for the pc equivalent sometime, which allow to run the code more... nativelly. But it is still emulation, and it can't be run directly. Then you ends up with some more insanity: modern console have an OS behind it, which provide some functions. Those are not much documented and have been reverse engineered to figure out what it do. That reverse engineering introduce bugs (or fix some, which may have been exploited), and may not be as optimised as the real one, in part because the hardware can change. Intel and AMD don't offer all the same opcodes. Same with a core2 vs an I5 for example. So those functions need to be more generic. On the real hardware they can sometime cheat, as they know that the hardware is always the same. And again, same thing for the emu, since the hardware change, the functions can't be as optimised for one hardware in particular. Sometime you can cheat knowing that this cheat will work, ex: a division by two take more time than shifting bits. The human equivalence is a division by 10, you can do the full division, or move the dot one position. If you know that this work on your hardware you can do that cheat, if there is a doubt then you need to do the full operation..."
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7v9f77 | when people say you are “sucking up the bandwidth”, what does this mean? | Technology | explainlikeimfive | {
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"think of the internet like a giant pipe from your house. How big the pipe is is the bandwidth. So the more bandwidth you are using the less other people can use."
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7va755 | How is data transmitted through cables? | Technology | explainlikeimfive | {
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"Depends on what kind of data and cable! There are many protocols but I guess the general concept is pretty much that one device controls whether there is a voltage or not (if it’s digital) and another device can detect it. There are some protocols (like hobby RC servo signals) that measure how long the voltage is high (and the signal repeats very rapidly many times a second) and others where the rate is determined by a clock signal, so every time the clock signal changes, the voltage on the line is checked again. One way to think about this would be that the device reads the voltage every time the clock changes and interprets the reading as a 1 or 0 (if there is a certain voltage or not). By sending very rapid signals, it can put together a string of binary bits that can be combined to form bytes and so on (depending on what the device is doing and how it is set up). Depending on the protocol there might be a “start byte” for example where the signal is held high for a certain number of clock ticks, and similarly an end byte, so the other controller knows it’s not misinterpreting something."
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7vbhu6 | Why do online video streams suddenly freeze but work again immediately after refreshing the stream? | I have a fast as shit connection yet whenever I watch love sports the streams will often work great for a period of time then freeze. If I refresh my browser the stream works great again for another period of time. I don’t understand. | Technology | explainlikeimfive | {
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"Your browser and the provider of the stream talk to each other via a continuous connection, which is initialised when you load the page and press play. This is a constant back and forth between the video service saying “I’m sending you this data, did you get it?” and your browser saying “I got it, and I’m ready for more, do you have anything new for me?” A whole host of things can cause that connection to falter, anywhere from your WiFi connection all the way up to the video service provider’s servers. Given that you stated live sports, it’s likely that they are very busy and receiving many of these connections - if yours gets lost in the process (it takes too long and times out, or their server has a hiccup due to the high traffic) your connection can falter - typically this will result in your browser saying “I’m ready for more, do you have anything new for me?” and not getting a response back, and so your video freezes. Refreshing the browser initialises a new connection. A well built video streaming service might have logic in place to detect this fault, and initiate a new connection behind the scenes to give you a seamless viewing experience. This isn’t as easy as it sounds to develop, and when “the user could just refresh the page” costs zero man hours for the company, it may not be a feature they provide."
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7vcqe1 | How are chip-readers more secure than magnetic strips? | Technology | explainlikeimfive | {
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"It's not necessarily the reader, but the card itself. In an eli5 sense, a magnetic stripe says \"I am X\" when swiped. It is extremely easy to create a copy of the card that also says \"I am X\". A chip card, when read, initiates a conversation like \"If you say you are card X, please complete this math problem using your secret ID number and give me the result\". Because the whole card's information is not transmitted during a transaction, it is much harder to create a copy. If a second authentication factor (such as a PIN) is not used, chip cards are still weak to physical theft and malicious usage of a card, neither do they protect against fradulent online usage.",
"If done correctly, they are chip+PIN. You need both the card and the number, that is how it was developed initially. Even without it, it's slightly better because a chip card is a bit harder to clone than a normal card."
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7ve1yk | how does finger print reading under the glass work and how is it so accurate? | When I saw the vivo smartphone coming out, the first thing I wondered was how this was possible. How can this technology go through glass and how is it so accurate? All finger prints are different, but the differenses are really small I assume. Which technology do you use to distinguish them? I hope you guys can help me out :) | Technology | explainlikeimfive | {
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"It will work on OLED screens as they don't need a backlight to display the image like LCD screens, instead they have thousands/millions of individual pixels that can change colour. In between the pixels are tiny gaps allowing the sensor to be behind the pixels and look through at your fingerprint."
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7vex1h | What's the purpose of unicode characters like Zalgo? | Technology | explainlikeimfive | {
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"It depends on the particular character. The most common way of creating Zalgo-style text is just adding a bunch of combining characters with normal latin characters to produce latin characters that have lots of random stuff attached to them. Look at an example like \"Z̢͍̯̻̦̣a̟̦̫ͅl̻̺̟̼g̰̜̝̥͡o͓̬\" The letter Z there is actually the Unicode sequence: U+005A LATIN CAPITAL LETTER Z U+0322 COMBINING RETROFLEX HOOK BELOW U+034D COMBINING LEFT RIGHT ARROW BELOW U+032F COMBINING INVERTED BREVE BELOW U+033B COMBINING SQUARE BELOW U+0326 COMBINING COMMA BELOW U+0323 COMBINING DOT BELOW So, it's a Z, followed by 6 combining characters that modify the appearance of the Z by adding additional pieces to it. Those combining characters are normally used to make either mathematical symbols or letters in various other languages. For example, retroflex hooks are used in IPA notation to indicate certain kinds of sounds, left-right arrows are used in certain kinds of mathematical notation, and latin letters with commas below are letters in some languages, most notably Romanian."
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7vg7l8 | Why exactly does the government want to privatize 5G networks? | Technology | explainlikeimfive | {
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"text": [
"To control it, and turn it off if people get too interested in having \"civil liberties\"."
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4
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7vhrdx | How can an ISP censor or alter web pages if they're encrypted via SSL/TLS? | Technology | explainlikeimfive | {
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"Even if the ISP can't read the contents, the origin and destinations are still possible to read. The ISP may choose to ban specific IP addresses, or inject messages into non-secure parts of a communication (like an advertisement that was sent without encryption and placed in a secure webpage)."
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7vibbj | Why can’t you click the iPhone button when the phone is dead? | Technology | explainlikeimfive | {
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"dtshim1",
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"text": [
"I assume you have a newer iPhone. On older ones, the home button is a physical button (like the power/lock button) that can be pressed when it's off. New iPhones: that's not actually a button! It's a touch-sensitive area that provides \"haptic feedback\": a little vibration at just the right time that convinces you that something was pressed. Look carefully and it's just an indentation the glass surface. That obviously won't work when there's no power or the phone is off.",
"On the newer iPhones. The home “button” isn’t actually a button. There’s a haptic engine (I think that’s what it’s called ) that makes the pressure sensitive home “button” feel like an actual button. It’s really just a small vibration. When the phone dies. No more juice for the haptic engine. & since it’s just pressure sensitive, it doesn’t recess like an actual button."
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7viqfz | Space Freezing | So, if depictions and movies are true: if a human is tossed into space and freezes upon contact, why don’t other things freeze in space as well (human in spacesuit, satellites, rockets, the flag we “put on the moon”, etc.)? | Technology | explainlikeimfive | {
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"> So, if depictions and movies are true There's the problem right there: they're not true, those aren't accurate depictions, and a human tossed into space wouldn't freeze upon contact.",
"Freezing is the process of a liquid turning into a solid. A hunk of metal and composite (i.e. a satalite), can't \"freeze\", its already frozen so to speak. A human being is 70% liquid water. There are plenty of things to freeze in a human.",
"IIRC, heat needs a medium to travel through, and as space is 'nothing' the heat loss simply isn't that quick. You'll be dead from lack of oxygen and depressurisation boiling your blood long before you freeze solid. Fun part is that you can boil and freeze at the same time."
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7vj5g7 | How do audio cassette tapes play different tracks depending on Side A or Side B? | Technology | explainlikeimfive | {
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"text": [
"Take two strips of paper. One one write banana. On th eother write orange. Rotate the strip with orange 180 degrees and put it directly under banana. Like this: banana ǝƃuɐɹo This is how it works but with magnetic tape, the old read heads only read the one half. Flipping tape reversed what side would be read. Newer decks just reversed direction and change position of the read head."
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7vnfwx | Why does it cost money for a video game developer to have breakable items in maps that they create in a game? | I saw this in Overwatch when Jeff Kaplan said in an interview that it costs money to have pots that shatter in their new maps and other things like balloons that blow up | Technology | explainlikeimfive | {
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"dttlchb",
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"text": [
"Because people don't work for free, and it takes work to make those breakable pots happen. It's not like the developer just says \"let things break\" and it just magically happens, people have to go in, write the code for breakable items, debug that code, and you need artists to make the models for the unbroken and broken pots. All of that takes time and effort, and it costs money to pay people for the work required.",
"You may have misunderstood. It usually costs performance to have more dynamic elements. Whenever a pot hits something (which is quite often considering it sits on the ground) it have to check if the force is big enough to shatter it. And when it shatters it turns into multiple fragments that all need their own physics calculations. It does cost them some time to code this but that is not so much unless you want to make everything breakable. But in terms of performance it can cost quite a lot."
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7vom7a | How does the tech behind the deepfakes work? | Recently heard about this controversy. Worried about the possible damage this could cause outside of fake porn. Curious to know how this works and how far this could go. | Technology | explainlikeimfive | {
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"The only person who could probably explain in very high detail would be the creator of that application of machine learning, but the high-level overview as I understand it is that the machine learning algorithm gets fed millions of frames of a particular face, then gets fed another face (of the porn actress in question) and it tries to correct the new face to look like the other face. In theory, this could be used to fake other sorts of video evidence in ways that would be difficult to detect using methods that at least I know about. The technology isn't perfect *yet*; apparently in the deepfakes there are moments where the face just blanks, mouth doesn't match the words, etc; but it's just a matter of time before there are improvements made to the code, and those flaws are worked out."
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7vp13t | What does it mean for a song to be well mastered/mixed? | How can you tell from listening to a song, if it's well mastered or not? How does a badly mastered song sound like? | Technology | explainlikeimfive | {
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"So, there are 3 major steps in creating the sound of a record. 1) Recording. When you actually put a mic in front of a guitar (piano, singer, etc.) and capture some audio. And/or when you synthesize some sounds directly. 2) Mixing. When you take all the recorded tracks (guitar, bass, drums, and vocals, for instance, will all be separate.) and put them together. The goal is to get each individual part to sound good, and more importantly, for the entire thing to sound good all together. \"Good\" is partly subjective, but a good mix will: * Let you hear each part as clearly as the artist intended * Nothing sounds out of place or \"off\" compared to other instruments * No parts get \"lost\" or become hard to hear in the mix * Overall volume is loud enough * Overall sound is clean, i.e no unwanted distortion * etc. A bad mix will have some instruments hard to hear, seem obviously too loud, or will have unpleasant tonal properties, i.e. they sound \"sharp\", or \"woofy\" or \"muffled', etc. Basically, any time you notice separate instruments as popping out of the song in a distracting, unintentional way, that's a bad mix. Or if the vocals just sound oddly cheap and weird. Etc. Mixing is also where you add EQ, Compression, reverb, and sometimes other artistic effects that change the sound. However, the line between mixing and production is a bit blurry, as is the line between mixing and mastering. Mixing is about 50% of what makes a record sound good, 40% is a good recording, and 10% is mastering. (my opinion.) 3) Mastering used to be, after they made the final mix, where someone would edit the audio so that it would play well on tape, CD, or vinyl record - it was a process specific to the medium and wasn't really artistic in nature. For example: Vinyl requires a special mastering process because the disc physically can't handle too much bass. They take some bass out at the mastering stage, and then the phono preamp puts it back when you play the record. So the mastering engineer's job was basically just to apply that process, not to do anything fancy to the sound of the record. Edit: forgot this part: Mastering can also encompass making the entire record sound good as a whole. So one song will have a similar character to the next. If the various mixes all sound a little different then the mastering step (whoever does it) will involve bringing them all into line. So if one song basically has more treble or bass than the next, they'll tweak it so they all sound like they came from the same record during mastering. These days mastering is also sometimes treated as a \"final touch\" on the mix where someone just tweaks things a bit and makes it sound extra-nice. But it's really almost more like a final step in the mixing process, than a technical process now. Since most music is distributed digitally, which has no technical requirements that would require audible changes to the mix, mastering engineers are more like \"final polish\".",
"Depends really. For example, the Beach Boys were famous for aiming for a specific sound, as if they were on the beach. They recorded most of the band in one set instead of individually recording everyone on separate tracks. As a result, they minimized the amount that could be twiddled with in the studio; every song has the slightly dampened, slightly tinny sound they were going for. In most cases today though, each performer/instrument has its own channel, and the studio records each one separately. Then all the feeds are run through algorithms that account for the specific recording equipment used, to filter out known audio effects. After that, the channels are mixed, levels adjusted, and desired acoustic effects manually added back to the channels. Mastering badly is usually the audio equivalent of a badly photoshopped picture; the levels can be off, the balance can be set wrong for the different channels, they can be panned badly, frequencies can be dampened or collide after the mixing causing undesired audio artefacts. Autotune can be abused resulting in flat but choppy vocals, flangers and reverb can muddy the sound. But at the end of the day, a badly mastered audio track is one that doesn't sound like the artist wanted it to. So you can get things like Cher's autotune spectacular that sounded exactly the way she wanted it, but by traditional studio rules, it was abysmal."
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7vq72f | Why do old forums have 2 or 3 words or phrases in every post linked to seemingly unrelated websites, usually to sell things? | I see this all over the place on older forums when searching various issues. Do the old website owners sell the website for advertising? How does something like this work? | Technology | explainlikeimfive | {
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"It's a type of advertising that was being pushed a little over a decade ago and it didn't go over well. Over time advertisers pushed newer types of ads (like autoplay videos) so it's mostly legacy websites that still have it installed. On a technology level most of them work via Javascript - you get served the page as normal, but once on your computer a 3rd party script in the site header runs and converts certain words into links to (supposedly relevant) ads. So if I wrote a post and mentioned **video cards** it would turn that into a link to a site selling video cards that pays for clicks or referrals."
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7vq86b | Why are three pin plugs better than two pin plugs in terms of safety, and why? | Technology | explainlikeimfive | {
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"text": [
"The ground (the third prong) is a failsafe that appliances and tools can use if they want to. If you have a power tool in your hand and something shorts out inside and electrifies the casing or something else touching you, you would get shocked. But if the tool was designed to use the ground, the casing would be attached to the ground, making the path of least resistance the ground wire and third prong, rather than into your hand. It's like a spillway on a dam or the holes along the rim of a sink or bathtub, there to take away extra water and dump it somewhere other than your floor, just as the ground dumps extra current back into the wall socket, rather than go somewhere current isn't supposed to, like your hand."
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7vs1ql | How do stethoscopes work? | Technology | explainlikeimfive | {
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"text": [
"They are the simplest thing in the world. Try rolling up a newspaper and listening through it. Sound is intensified*. Stethoscopes are just a more precisely engineered version of that. The sound waves decay much less when separated from the rest if the air, due to lack of friction against other air molecules. *intensified may not be the best word. It sounds much louder than you would expect. It's probably better to say sound normally gets quieter very quickly with increasing distance from the source. Isolating it from disruption from air currents, other noises etc means that it arrives at your ear having kept a decent proportion of its original energy."
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7vtwo8 | What is the kernel of an operating system? | For some background, I am currently a graduate EE student. My research deals with implementing countermeasures to thwart software attacks in C/C++ (e.g. buffer overflows, format strings, etc.). My advisor mentions the Linux kernel often when talking about our work, but I still can't understand what he means by it. What I find confusing trying to differentiate between the kernel, the BIOS/UEFI, and the operating system. If anyone is knowledgeable about the topic and willing to share that information, I would be really grateful. Thank you. | Technology | explainlikeimfive | {
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"The BIOS/UEFI is firmware, i.e., it is in a ROM on your motherboard. It's the first program to be executed and it will load the actual operating system in memory (RAM) usually from your hard disk (or SSD now). UEFI is the \"new enhanced\" BIOS. Usually written by the motherboard vendors but open-source BIOS/UEFIs exist as well. The distinction between kernel and OS is more subtle. The kernel is the subset of the operating system that is running in kernel mode on the cpu (also called supervisor mode). It's a protected mode on the cpu in which you can execute special important instructions that only an operating system must use. The linux kernel is exactly that and contains parts about scheduling programs/threads, managing memory and creating the \"file abstraction\". It is really the core of the operating system. So what's in the OS but not in the kernel? Userspace programs that accompany the kernel. Examples are the standard C library, shell terminals, any GUI/Window system, any API developers can use to develop programs. I guess you can even consider default wallpapers as part of the OS."
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7vuky3 | How will the Tesla Roadster orbiting the sun be affected by being in outer space? What would happen to the tires? Paint? Any liquids inside? | Technology | explainlikeimfive | {
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"text": [
"I predict it's red paint will be bleached white before it completes its first orbit past Mars.",
"I know this doesn't answer your question, but the car was most likely modified. Wheels locked in place, liquids drained, etc. Possibly the engine taken out for weight. So it's probably not just a regular car in space"
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7vuq92 | Why internet companies don’t match upload speeds with download speeds. | Technology | explainlikeimfive | {
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"text": [
"Because that would be a waste of bandwidth for most users. Your common internet user is a consumer of the internet, they are watching videos, browsing websites, and downloading things. The average user is not hosting a website, uploading lots of things, etc. So they set upload speed high enough to more than handle common usage. If you have a business that does a lot of uploading or hosting of things there are business class packages that have high upload speeds."
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7vvd83 | How does Netflix acquire shows? | This is something I've always been interested to learn but never seem to be able to find any good answers; Does anyone know how Netflix actually acquire shows? For instance, there's the whole Cloverfield sequel but no original thing going on. Sometimes there will be a series that only starts from like, series 4-7 but no 1-3 (can't remember what series it is). I heard from a movie making group nearby that last year Netflix went to Vancouver and offered 99% of short films/feature films etc something like £200,000 to own the rights for 4/5 years, and if they choose to develop it, then they do, and if they don't, the writers aren't allowed to touch it until the time has passed. So, does anyone happen to know? | Technology | explainlikeimfive | {
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"The same way that all television stations do. They either buy the rights to broadcast a show from those who own the show (how they get most movies and tv shows), or they purchase the show in its entirety (netflix original is the label they use) for distribution within a given country."
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7vvehv | Why can't the Internet be made completely secure | Specific networks or transmission/reception has an increased level of security, example for banks or governmental bodies. Why cannot the entire Internet be made secure in the same manner? | Technology | explainlikeimfive | {
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"There is always a trade off between security and usability. Take for example a login to a webpage: This list goes from low security - high usability to high security - low usability 1) only put in your username 2) put in your username and a password 3) username/password and mobile phone code generator 4) smartcard + pin (need smardcard reader etc) 5) send a copy of your ID everytime you will login 6) drive to Website HQ and personally ask for a login.. You see.. especially the last 2 are secure.. but no one wants to do things like this in reality. The more secure you make something the harder it is to use or to develop/operate (in most cases).",
"The main problem creating insecurity are humans. If you could get rid of all humans you would not need to fear anymore hackers. No system is 100% secure. Networks used by banks may be slightly more secure than others but they are still nowhere near completely secure. Government IT is really not as secure as you think it is.",
"The internet is like a neighborhood. Each connected device is its own house, and each house has different points of entry. You can think of things like your bank as being that guy with security cameras on every corner, double-thick steel doors, and trip mines on the walkway. Your home network is more like a pre-fab home tucked away on a quiet cul-de-sac. Internet security can be analogous to the entryways in a home. There are windows, doors, vents, etc. Sometimes information can be seen but not touched (windows that don’t open). Sometimes information can get in, but not out (windows with a screen). Sometimes information can go both ways, so long as you have a specific login (a door with a key). And sometimes *very specific* information can flow freely (air vents, pipes, etc). That being said, hackers are like burglars. The average “hack” is just a random sniffer that walks around your house and checks out what windows and doors you have open. It might see a screen over an open window and think “too hard”, or it might find a door was left unlocked or open and think “easy money”. More complex, human hackers will try to find weaknesses in the House, such as a closed, but unlatched window, a crawl space with access to the home, etc. and some high-tech hacks can try to pick your lock, break your windows, or break down the door. The biggest threat to cyber security, as mentioned by someone else, is people. Sometimes simple mistakes are made, such as leaving the door open, a key under the mat, etc. Many hacks exploit the worries of others. They will call you and say your neighbor is in trouble, “go help quick!” In your rush out the door you forget to lock it, and they rob you while you’re away. Or they might disguise themselves as your nan and knock on the door. You open it only to find out that it was the Big Bad Wolf all along. Barring human error (or stupidity), no network is truly secure. Anyone with enough time and money can break in, if you’re worth it. A door can be opened, a window can be broken, a flaw in construction can be found and utilized, or someone can just straight up cut a whole in the wall. The real question is: “are you worth it?” Remember your bank with the steel doors and the trip mines? Well, an Oceans-Eleven level of hacking can still disable them and force/trick their way in, because that guy has gold inside. But you in your average home don’t have anything much worth breaking in for, or at least it can’t be seen from a cursory glance through a window. As long as you keep your door locked, you’re most likely fine.",
"As long as there are people involved in using it, there is no such thing as completely secure. If I make an impenetrable vault and then you write the combination to the lock on a sticky note and put it on the edge of your monitor, our security is fucked and it is not my vault design's fault."
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7vvmdx | Why do some tracks on CDs have "negative time" before the actual track starts playing at 0:00? | Technology | explainlikeimfive | {
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"The CD has a table of contents which lays out the tracks, where they are located on the disk and can include a 'pregap' before tracks which will probably show as a count down. More info: URL_0 and a sample specification for a CD TOC: URL_1 Why? Presumably for a nice pause between tracks without having to have a gap at the end or start of the track if they are played individually.",
"It’s funny and kinda sad that the negative space before tracks, specifically before the first track of albums, is going to be a thing of the past. Some artists have used this to “hide” “secret” songs. I think specifically of 311’s record Transistor, which has an almost two minute intro to the song’s title track that exists in negative time. Being that it’s the album’s first track, it can only be heard if you rewind the CD back from it’s start. Kinda cool.",
"In my day, the early aughts, rappers fancied a comedic skit in between songs. Sometimes humorous, sometimes as context for the next song. Sometimes just 'cause. Busta Rhymes' \"Extinction Level Event\" had it's skits stored in the pregap so if you listen straight through you get the full experience, but if you skipped around the CD the track would go straight to the song. Still magic to me.",
"My time to shine, professional CD mastering engineer here. The pregap shows a negative count before each track and is usually done to conform to the Red Book CD Standard developed by Sony and Phillips int he 80's. The CD players we had back in the 80s were primitive by today's tech so the pregap became part of the standard so that players had time to mute and unmute between tracks. On an old player if you didn't have a pregap between tracks it might not be able to do the switch smoothly enough and you'd likely hear a clip. Fun fact: You can extend the pregap and hide unindexed audio within as a sort of 'secret' track so to speak.",
"I remember I had a 5-disc turntable for CDs, and the remote had not only the track-skip button, but also the index buttons. I had only one CD that used indexing: Jean-Michel Jarre's \"Chronologie\". Indexing would jump you to certain key sections of songs within tracks. Never saw that again on any other CD.",
"In some cases, to hide a secret \"0\" track. \"Token Back to Brooklyn\" on They Might Be Giants' album Factory Showroom had a hidden track like that. You had to play the first track, then rewind. Skipping back wouldn't do. You had to use the rewind command, not the \"previous track\" command (in my player's case, holding the button down instead of clicking it once).",
"Not sure if this was said yet, but some cd's have a hidden track before the first track. It's not exactly the same as the gap between songs, but it's also cool. You just rewind from the start of the first track and it goes into negative seconds for a bit, then plays the hidden audio.",
"The simplest eli5 explanation I can think of is that artist spend a lot of time laying out a specific amount of space between songs when listening to an album in long form, so it flows. But cds allowed that space to be ignored when skipping track or playing at random. A merging of artistic expression with modern convenience!!",
"Anyone ever listened to the beginning of “Losing Streak” by Less Than Jake?",
"I had nirvana unplugged on cd. Thought it was cool the audience applauding was included in the negative time",
"When I used burn CDs the program I used actually allowed you to set that time. 1,2,3 seconds between each song or none.",
"There’s an AFI album that has a secret song at the beginning of the cd. I forget which album.",
"Might be slightly off topic, but this reminded me that a band called Agoraphobic Nosebleed released a [100 track album on a 3 inch disc]( URL_0 ) using the 'rewind CD' method.",
"There is a Queens of the Stone Age record (Songs for the Deaf, I believe) that one can rewind at the very start of the CD so that you can hear them do stuff at like -00:10. Amazing album. Man..."
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7vw36e | What does "bit" mean, in reference to Encryption? i.e 4096-bit encrypted | Technology | explainlikeimfive | {
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"text": [
"It refers to the size of the encryption key. A bit is a single binary digit - 0 or 1 - so 4096 bits means there are 2^4096 possible encryption keys. A naive approach to breaking the encryption would be to try every possible key, so you'll have to try 2^4096 different keys (which is a lot). Note that 4096 bit usually refers to public key encryption, which usually uses prime numbers. So 4096 bit means that the prime number is 4096 bits long, which is about 1200 digits."
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7vwjxj | What is the difference between an active and a passive radar? | Technology | explainlikeimfive | {
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"> What is the difference between an active and a passive radar? An active radar actively sends out radar pulses which it listens for the return signal from. A passive radar does nothing but listen for the return pulses from other radars. It is really as simple as the definition of the words \"active\" and \"passive\"."
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7vx0aa | What are drivers? | And how do they differ from other software or programs on my pc? | Technology | explainlikeimfive | {
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"I assume you mean computer drivers. They are instructions on how to interact with a particular kind of hardware. For example if you have a keyboard and a button is pressed it will send a signal to the computer, but how would the computer know what button that signal means? The driver is what handles that.",
"Imagine that you are an owner of a company where you are the only person (**windows, macOS**). Now as a company you receive requests to do some services (paint a wall, build a bridge etc.) But you dont know how to do these things. So you hire people with special skills (**drivers**) that can do these things, and use the english language to communicate with them (the **api** between ths two). With these personnell (**drivers**) you as a company dont have to know how to perform specific tasks but you can still solve them. In the context of PCs, Microsoft doesnt know what hardware other companies will make that windows has to work with, so they define APIs so that hardware makers can make their hardware work under windows (even on an old version of windows).",
"Drivers are software written by a hardware manufacturer so that they are accessible and usable by your PC. Two pieces of hardware - lets say a GPU for instance - designed by Nvidia and AMD are supposed to to the same function, but they obviously use different hardware. It would be impossible/impractical for a game developer to write code into their game to specifically address every single product that these companies put out. First it would require intimate knowledge of the hardware - which AMD/Nvidia would not want to publicly release - and second, it would be so time consuming that they would spend all of their resources on that. So AMD and Nvidia create drivers since they have intimate knowledge of all of their hardware. The drivers address the GPU hardware at the lowest level, implementing an API (Application Program Interface) standard such as DirectX, OpenGL, or Vulkan. So now a game developer instead of writing their game and directly telling the GPU hardware what to do, it uses API calls. The benefit of this is that they now no longer have to care what hardware is running on the PC, because all of the hardware conforms to an API standard. Imagine being at a restaurant and ordering a burger. Would you yourself go into the kitchen and direct the cooks on exactly how to cook it? If everyone did that it would be a time-consuming disaster, with inconsistent results. Instead we go through an intermediary - your server (analogy for API). You tell your server you want a burger, and they go to the kitchen and tell them to make a burger. No matter how many times someone orders a burger this way, the results are consistent and predictable. So a driver is how hardware is talked to (addressed) at the lowest possible level, and an API is how software talks to drivers. Doing it this way means that there is a standard, uniformity, and compatibility which allows you to use varying pieces of hardware without issue."
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7vx6en | What are they using all that supercomputers for? | I know they use it for calculations about space and some military stuff of course. But what is the other usage? | Technology | explainlikeimfive | {
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"A lot of them are used by various world governments to do the things you said. A lot of them are also used in academia to solve problems. Weather patterns for example, is one of these problems that are based in Newtonian physics (that is, “normal” physics like what goes up must come down), and among the equations to be solved are the Navier Stokes equations. These NS equations are so important that in fact they can, and are, applied to basically every single problem you can think of that involves a fluid (gas, water, air, liquids, oil, etc) moving from A to B. So, that means it can be used to model jet propulsion (gas is moving out the exhaust), rocket engines (gas/mass is moving out the exhaust), new airplane designs (air is moving over the wings), etc. The other thing about these NS equations is that *they currently can not be solved*. There’s actually like a million dollar prize for anyone who can prove whether or not they can or can’t be solved. Anyway, despite not being able to be solved, we can use supercomputers to approximate a solution to them. How do we know the solutions are right then if they can’t be solved? That’s up to the scientist to interpret. These problems can be very “big” and take up a lot of computational power, so in general bigger computer = more detailed models or faster results, pick one. The NS equations are just one example. There are similar sets of equations for things that are not fluids, like metals and solids. You can combine models with fluids and solids. Then, there are other things you can use a supercomputer to model: electrical models, mass transport models, etc. These are all still in the realm of “normal” physics, using “normal” computational methods (finite element/volume/difference methods). For all of those things, you can apply different modeling and solution techniques, some of which can possibly take better advantage of the supercomputers. For example, you can use Lattice Boltzmann methods to solve all the things I mentioned. THEN, you have the real of “not normal” physics: quantum physics and quantum chemistry. In those models, people are simulating individual molecules and particles and atoms. They are simulating and measuring things that we literally cannot see, sometimes we literally don’t even know if they exist. These models scale up relatively well: the bigger your computer the more you can model, or the more “time” you can simulate, etc."
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7vyad1 | how does A.I. learn? | I get that you reward the system for accomplishing a goal, but then isn't the programmer still ultimately controlling what happens? | Technology | explainlikeimfive | {
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"That depends on what you mean by \"control\"; Consider that programmers of non-AI programs still introduce bugs and unintended behaviors all the time. We're dealing with complex systems that are difficult to predict all the time in computers; AIs are meant to be even more unpredictable, able to to take in thousands of variables and make a decision on the correct course of action, in a way a human couldn't possibly do on-the-fly even if they knew the equations. So while the learning algorithms may be coded by a human, that doesn't mean a human can predict the results.",
"CGP Grey did an excellent video about this. And it can be summed up pretty easily. The programmer builds 2 bots. A teacher and a builder. The programmer also sets up an AI. This AI gets acted upon by the teacher and builder bots. The AI being a network of neurons and nodes that take in information and output. In Grey's video the AI takes in photos and outputs if it thinks the photo is a bee or a three. Initially the AI is set to randomly output or make decisions. The teacher bot tests the AI and gives it a score. Since it is guessing randomly is does not score very well. The builder bot takes the highest scoring ones and adjusts a couple dials in the AI. Those dials being weights and values in the neurons and nodes of the AI's brain. Then the AI is tested again. It gets scored and is sent back to the builder. The builder bot makes more and more adjustments and eventually you have an AI that can do specifically what you trained it to do.",
"Kind of, the programmer gives the program many parameters that the program can adjust on its own. Of course that only works in a range that the programmer build it to work, but the programmer doesn't set up all those parameters and the program doesn't know exactly why the parameters chosen by the program work the best. Sometimes it's very intuitive and sometimes it can be very strange and unexpected. AI usually finds which parameters work best by training on a set with a known solution. So you basically have to give the program a very big set of example problems with solutions. And then the program just tries out different parameters. If the solution is good it slightly adjusts the parameters trying to make the solution a little better and if it was completely off it makes a big adjustment. If you have lots of training data that usually works very well. But the program can't learn something completely new. It can only self adjust some screws that the programmer build in. A simple example would be the summing up two numbers. Instead of just programming number_1 + number_2 you add variables that you can adjust a*number_1 + b*number_2 Now your program can try out random values for a and b. And depending on the training data it might find that 10 + 5 = 15 gives very good solutions for a = 0 and b=3. But that won't work for 10 + 5. So the hard part is figuring out how to make your program adjustable in the first place, how to rate the result of your sometimes rather random adjusted results and then you usually need some rule for the program on what to change. In this case you'd probably say if the result is too high make a or b lower. But it would work better if you could find a way to test whether a or b is too high. So yeah self adjusting is probably a better way to describe A.I. at least at this point in time."
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7vybqw | How is an IP address 4 bytes? | From my understanding, 8 bits=1 byte. 1 byte is equal to 1 character. How is an IP address equal to 4 bytes if there can be more than 4 characters of numbers? If an IP address is 20.30.1.4 wouldn't that be 6 bytes? Thank you in advance! | Technology | explainlikeimfive | {
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"1 byte isn't equal to 1 character in all applications, it just so happens that ASCII uses an 8-bit encoding to store characters in a binary form. an 8-bit binary number is simply a number in binary with 8 digits; when converted to decimal, they can range between 0 (00000000) and 255 (11111111); Much like how in base 10 we have each column of digits equal to a power of 10 (1, 10, 100, 1000, etc), in binary each column of numbers equals a power of 2 (1, 2, 4, 8, 16, 32, 64...) The sequence is as follows: 1 = 00000001 2 = 00000010 3 = 00000011 4 = 00000100 [...] 253 = 11111101 254 = 11111110 255 = 11111111 so when you look at an IP address of 20.30.1.4 what that is really telling the computer is that the address is 00010100.000011110.00000001.00000100",
"Each segment of an IP address has 256 possible values (0-255). An 8-bit byte can express 256 (2^8) possible values, and thus an ipv4 address can be expressed as 4 8-bit bytes.",
"1 byte = 8 bits = 256 possible values. None of those sequences of bits have any inherent meaning. If you want to make 8 bits a \"character\", you make a table of 256 possible characters and each number maps to one. With an IP address, we look at it as 0.0.0.0 to 255.255.255.255 - but it's really a single 32-bit number."
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7w0a7u | Why do some screens' colors get distorted when viewed from extreme angles? | Technology | explainlikeimfive | {
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"The crystals in some types of Liquid Crystal Displays (LCD for short) are carefully aligned in a way that's the best from viewing from the front. That's the \"TN\" type. If you're viewing from an angle, the light isn't shaped in the way that it should be, and that causes the distortion. There are more modern display types that do not suffer from this issue. EDIT: I suppose I might also add that the crystals are there to act as colored filters. Essentially, the backlight passes through them to get the colors that it actually has to display. The way the crystals do it differs between panels. The way they work in TN makes it suffer the worst from the distortion as a side effect, VA is an improvement, and IPS offers the best viewing angles. Though it is important to consider all other aspects of various panels when purchasing one, not just the viewing angles."
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7w113b | what an API-key is and how to use it | Technology | explainlikeimfive | {
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"API key is a key (just like a key to your front door) that identifies you. without API key, the system will either not respond or not give you full access to its capabilities. just like if you didn't have the key to the apt building, you can still get in the first front door, but not into any apt."
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7w1zb6 | How does a computer determine when a syntax error has been made? | Technology | explainlikeimfive | {
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"Syntax errors are found at compile time while it's trying to understand your code and make assembly. They're easier to see in a language like C that requires semicolons. Let's take the following example Int x=2; Int y; If(x==2) { y=4 Else { y=7; } There are two issues in there so the compiler will read though it and come across the line y=4 but due to the missing } and ; it reads as y=4Else{y=7 You can't store the value 4Else{y=7 in an integer variable so clearly something went wrong. The missing ; also messes with the interpretation of every line that follows so sometimes you'll miss one semicolon and get a thousand syntax errors because now nothing makes sense"
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7w3b64 | GIF File Size Increasing Instead Of Decreasing, Why? | Technology | explainlikeimfive | {
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"My best guess is that resizing is making the image more complicated. Imagine a hand-drawn 128 x 128 image of the American Flag. The whole image contains just 4 colors: red, white, blue, and black (for the background). This image will compress extremely well, because there are very easy patterns - dozens of pixels in a row all the same color. Now you resize the image to 32 x 32 pixels. If you use a smooth anti-aliased resize, it's going to blend the colors in the resized image. Now the image will have dozens of different colors - lots of shades of pink, light blue, and gray, for example. Now there are almost no patterns - every pixel is a different color than its neighbor - so it won't compress well at all."
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7w7dwy | Why does iTunes check for updates IMMEDIATELY AFTER installing updates? | Technology | explainlikeimfive | {
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"When you're releasing a new version, you only test a certain amount of versions back for upgrade paths. It takes resources to try and test more and more versions. As a result, you start dropping the single upgrade support and relying on the system to help the user get there over one or two upgrades."
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7w8pg5 | How do high speed (slomotion) cameras work. If you are filming 1,000,000 FPS wouldn't that mean your fastest shutter speed is 1/1,000,000th of a second, how do the cameras get enough light at that quick of a shutter speed? | ELI5 how high speed cameras work | Technology | explainlikeimfive | {
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"As others said we blast the area with light and/or crank up the gain on the camera. If you look close you'll often see the slo mo images are grainier than the other video sources because the sensor is struggling to capture the light. Source: I'm a professional cinematographer.",
"Lots of ligths, bigger lenses to capture more ligth and mostly lower resolution, so u can add the ligth hitting multiple pixels next to each other"
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7w8r0t | With today's technology why is it so hard to make counterfeit coins or counterfeit bills? | Technology | explainlikeimfive | {
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"The same answer - today's technology has been used to make bills much more difficult to counterfeit. High value bills have dozens of countermeasures - from the paper, the ink, the printing techniques, etc. - all designed to make it difficult and expensive to do on your own. This deters most people looking to counterfeit - they don't have the skills or the investment money. For lower value bills/coins, there are fewer countermeasures, but that is because the payoff is so low. No one wants to counterfeit $1 bills or quarters because you have to make a ton for it to be worth your while.",
"We keep upgrading the security features on currency to keep it hard to counterfeit. It's not really practical to counterfeit anything less than $20 bills. Coins are right out. A quarter weighs 5.67 grams so making $10,000 in quarters would require 220 kg of metal. That's impractical Bills have fancy colors, fabric paper, and security strips. The goal is to make it cost more to make the counterfeit money than it's worth, or at least close enough"
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7wa7sp | Would it be possible to put solar panels on top of the trailer of a driverless electric semi to where it would be able to constantly recharge itself and make the trip non-stop | Technology | explainlikeimfive | {
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"Yes, it's likely possible. It's going to come down to how efficient you can get the solar panels/motors and how well you design the vehicle. However, it would be very, very slow. You couldn't even maintain a walking pace because solar panels don't provide anywhere near the power required. A much better option would be to use a concentrating solar power plant to charge batteries which are swapped out at points along the trip.",
"Nope! It simply isn't enough power A big trailer might be 4 meters x 15 meters, that's 60 m^2. Solar illuminance is roughly 1000 W/m^2. That's 60kW or about 80 HP max. That's less than your average sedan and less than a third what a semi has. You're not going to be pulling a big load and certainly not non-stop",
"Semi? probably not at this stage. There is a 300 km solar car competition that goes on in australia every year you could look up if you are interested. They aren't good enough yet for load bearing cars, and they need a lot of maintenance (dust is really bad for solar panels), but the concept is there. So the answer is possibly in the future, in fact thats a goal, but not right now."
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7wa9ed | How is source code kept from the public? | Technology | explainlikeimfive | {
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"In a nutshell, program source code isn't everywhere. A program gets compiled from source and turned into a binary format. That is what gets installed and distributed when you download a program. The source is typically only used to compile the program once. (Ignoring interpreters, JIT, etc). That said, there are decompilers but they can only do so much. Comments and variable names are lost and the optimization process often makes a non human readable mess of things.",
"Because normally it's kept private if it's important. Front end code is easy to see - all you have to do is click \"view page source\" in your browser. So, you typically find ways to keep important things out of that code. Back end (or code that is typically run on the server) is normally kept locked in a private file system somewhere if it contains \"secrets.\" The only way to get this code would be to get onto the server to get the code artifacts (and try to work backwards to get the source code) or get into where they actual store the code (normally in a private repository). There are also things like applications you download. These don't really put source code on your phone/pc - you install packages that are typically made from source code. There are ways to get the code from them - but the source isn't really meant to be available. Again - most applications tend not to have \"secret\" code in them for this reason."
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7wde4o | How is a vending machine able to know the differences of how much a bill is? (like 1's, 5's, etc)? | Technology | explainlikeimfive | {
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"I actually know quite a bit about this. My best friend writes the code for the optics that go into machines lime this and a ATM's. Basically what happens is the US bills have water marks and other identifying features on them for safety. When you use a specific light they light up brightly. A photosensor is able to identify the image and thus the bill it is. A 1 has no mark. A 5 I think has Lincoln on it, a 10 is Hamilton and so on. So the computer matches it up with a portrait like a game of guess who and then identifies the bill that way. This is only one way. Some higher tech machines have more sophisticated means. Some include identifying the specific ink that's on the bill, identifying micro print and so on. It'll depend on the level of security required by the customer as to which programs get put where. For instance vending machines the risk of loss is relatively small. So a less advanced identifying algorithm is used. An ATM involves a high level of risk so an advanced algorithm would be used. So on and so forth. Edited ATM",
"Same way as you do, it looks at them. It looks at size and at the print. It has images of how they should look, and if it looks enough like one of those images, it accepts it.",
"So it seems newer machines work based off of image recognition, but how did older machines work, like from 30+ years ago?",
"To add to this, why does it seem like the readers haven't improved in decades? Seems like any wrinkle will get rejected. It hasn't learned how to accept a bill put it with Washington facing down?",
"The programming depends on the manufacturer, but most validators use a combination of optical scanning and magnetic signature. An LED shines light on the bill and a light sensor reads the reflection. Mars VN series validators were the first ones (that I'm aware of) that used a purely optical scan. (And a frequency coupled power supply, which was cool.) I spent 8 years repairing bill validators and coin changers for a living.",
"This has evolved over time. If anyone remembers the Jolly Roger cookbook from the 80s/90s you used to be able to tear off s little square part of bills on the bottom right (about an inch from the side). This would allow the machine to recognize the bill but kick it back at the last second due to the tear. You would get the item plus your bill back.",
"Old is weight, new ones lasers the material and size, very old sizes get split down as the holes make the small fall in a slot and the bigger to the latter slot etc, then a sensor sees one small, 3 big etc.",
"Tiny little bumps and markings are read by a laser in the ATM. Specifically the raised ink on the 5, and 10. The ATM \"reads\" it and recognizes it to be that of the correct denomination.",
"Current bill validator technology has come a long way from what it used to be. The BVs we use at work (I'm a slot technician at a casino) actually take a digital image of the bill and check it over thousands of points to ensure legitimacy. They store a digital image of the last bill in, bill history, acceptance rates, and other info. This results in a very very very high rate of bills being accepted even if they are in poor condition, while rejecting almost every counterfeit bill. The BV then sends the info of the amount to the CPU.",
"Follow up...before there were fancy LEDs and lasers and all the different kinds of bills...US money was basically all similar. How did those machines work?",
"The cheapest and most finicky method that I know of: The ink in US currency is metallic. When passed by a magnetic reading head, like the kind in a cassette player, the bill will create an electronic signal. Imagine this signal is a single song. In reality, if you played it, it would be like a “bzzzrrp” noise. Every denomination plays the same song. So all dollar bills play the “Washington” song and all fives play the “Lincoln”. So on and so forth. The vending machine has a chip in it that has a library of all these songs. Some only have one song saved (almost always for a dollar bill). So the machine will play the song, and then try to match the song it just heard to all the songs in the library. When it finds a close enough match, it’ll add the value linked to the song to the tally of money entered. Sometimes machines can only recognize the song from side a of the bill, and it’ll show you that you have to insert the bill face up. Some machines know both sides. Also, because bills get handled and bent up and disfigured, sometimes the song doesn’t play right and the vending machine can’t find a match. In these cases, the machine will spit the bill back out. This is my favorite method because it’s old, it’s cheap, it’s everywhere, and it’s REALLY cool. Newer methods are laser readers, photo readers, combinations of all the above..."
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7wfpvh | How does skill-based matchmaking work in multiplayer video games? | Technology | explainlikeimfive | {
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"The algorithm can vary from game to game. One that I'm familiar with is he [Glicko]( URL_0 ) system which assigns players values which go up or down depending on the rating of the other players and the outcome of the game. If you are the underdog and win, you gain more points than if you rated higher than your opponent before the match. But likewise lose more if you were ranked higher but end up losing. Games with team play will have algorithms to generate an overall team rating and another algorithm how to add or subtract points from individuals after the match. Of course, just having a rating is one thing, if you are playing a team game, matchmaking itself needs another algorithm to try to generate teams of equal skill. If you don't have enough players in the player base or there are simply not many players at your skill level, the matchmaking system may start pulling players further from the team average over time just to fill out the team."
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7wjeid | How could we stay on the same radio tune when we are driving? | The Doppler effect (or the Doppler shift) is the change in frequency or wavelength of a wave for an observerwho is moving relative to the wave source. How could we stay on the same radio tune when we are driving? | Technology | explainlikeimfive | {
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"The doppler effect does effect the radio, but not enough to mater. An FM station doesn't transmit on exactly one frequency. It spans a range of 100 to 200 kHz (depending on where you are) So you might think that 100 Mhz. In reality that is where the transmission is centered. On an old dial radio, you may not be exactly on the center frequency and hear the station just fine. So as you drive the Doppler effect will change the station you are tuned to by a tiny amount. If you think you are tuned to 100, but you are actually tuned to 100.01 or 99.99 MHz as you drive around, it just doesn't matter. You still hear the frequency loud and clear.",
"The Doppler shift is pretty small at those speeds, 60 mph is 26 meter per second which equated to a shift of 3x10^8 / (3x10^8 + 26) Which is practically 1 or no shift"
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7wkk00 | How do you record your TV screen when playing PlayStation while at the same time filming yourself playing games like the YouTube vloggers do? | Technology | explainlikeimfive | {
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"To capture the TV screen, you would use what's called a capture card, such as [this one]( URL_0 ). Your console output goes in one end of the card, and the other end of the card goes out to the TV. A third connection runs to a computer where it can be recorded by recording software. This connection contains all the same video and sound that goes to the TV. To record yourself, you would just connect a standard webcam to your computer and either 1) record it into the same program, or 2) record with a different program and edit it together later",
"There’s a device called elgato. It does what you’re asking for. [Elgato ]( URL_0 )"
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7wm9p4 | Newton’s method of successive approximations to find the square root of a number | Technology | explainlikeimfive | {
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"For a nonlinear function, f, it is usually impossible to solve an equation of the form f(x) = 0. Despite this, solving problems of this form is of great interest for a variety of applications in math, science, engineering, etc. These solutions are called \"roots\". To contrast this, when L is a linear function, one can (almost) always solve the equation L(x) = 0. Newton's method relies on approximating f by a linear function, L which is called the differential of f. Now, if f ~ L is a \"good\" approximation, then you expect f(x) ~ L(x) so if L(x) = 0 then this must mean that f(x) ~ 0. The other side of the method is based on the fact that L is a \"local\" approximation i.e. it only approximates the function f when you are \"near\" the specific value, x0, where it was computed. The method then relies on the fact that for (most) functions, if you start at a guess for the root (solution to f(x) = 0), compute L at this guess, then solve L(x) = 0 to obtain an updated guess, this guess is often closer to the true root so you can repeat this procedure and it will converge to a very good approximation for the root."
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7wnt9e | Why is natural gas an energy source but hydrogen gas and fossil fuels are considered forms of energy storage? | Technology | explainlikeimfive | {
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"Both natural gas and fossil fuels are considered to be energy sources, because we can extract them from the Earth and then burn them for energy. Hydrogen is not considered to be an energy source, because we can't go out and just dig some up. We have to make it, usually by spending energy to split water into hydrogen and oxygen. When we later burn the hydrogen, we get *less* energy back than we spent to produce the hydrogen in the first place. Thus hydrogen is a form of energy storage (storing the energy used to perform hydrolysis on the water, and getting some of it back later)."
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7wolvm | Is a regular audio file with sounds larger than an audio file of the same lengths without sounds? | Technology | explainlikeimfive | {
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"To a degree, it would depend on the format of the audio file. If it is a file type that allows for compression, then something with no sound would be highly compressible, and have negligible size, whilst the version with audio would be less compressible and so be bigger. If it was a format without compression, then both would be the same size."
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7wq83d | ultrasound imaging for cancer | Due to recent events in my life, I'm curious about ultrasound imaging. How can they tell the difference between a malignant tumor and a benign one? How do they decide wether or not to do a biopsy? | Technology | explainlikeimfive | {
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"The ultrasound will provide clues to the size, shape, and density of tissue, such as a tumor. Using Doppler technology (think storm forecasts), your medical team can gain information such as blood flow. Depending on your body and symptoms, your doctor might schedule several ultrasounds to compare the mass over time. This can provide clues as to whether the mass is growing, and at what pace it is growing. Ultrasounds are non invasive and can provide some useful imaging. Best to rule out benign growths before more invasive biopsies."
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7wviui | Why do some CD-ROM Discs Warn you about NOT playing track one in your CD Player? | I was cruising YouTube when I found this and it really got me thinking, how can CD-ROM data harm your CD player? [Here is the video that got me thinking about this]( URL_0 ) | Technology | explainlikeimfive | {
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"The warning isn't about breaking anything. It's just that some CD players will try to play the data as music and make awful noises.",
"Playing the data track through speakers results in some really loud and harsh noises which can damage your hearing and/or your speakers.",
"It can't hurt the player. If you put a data CD in an audio CD player, it'll try to interpret the data on the track as audio. Either it won't play at all, or it'll just blare garbage out of the speakers. Some CDs back in the day came with data on the same disc as audio - kind of a two for one deal. In those cases, track 1 would contain the computer data and the rest would be audio. It was done this way so computers would understand the CD as a data CD when it's inserted. Thus, they would warn you to skip track one when you wanted to play the audio in a standard CD Audio player.",
"This reminds me of the 90s when we had X-Wing Vs Tie Fighter on disc for like Windows 98? And my dad would pop it into the CD player in the car and you could listen to the whole soundtrack",
"Some speakers can be damaged by some sounds which don't appear in music but might appear when interpreting CD-ROM file system data as sound."
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7ww6k4 | Why do books always have 1-2 blank pages at the end? | Technology | explainlikeimfive | {
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"The page of a book is actually a portion of the sheet that is printed, and then cut up. So imagine that the press uses a sheet that it cut into 16 pages (that is, cut eight ways, front and back). If you have a 78 page book, they are going to use five sheets. That's 80 pages, so, 78 for the book and two blank pages at the end.",
"Because of how the pages are printed. They’re not done a single page at a time, but on larger sheets called signatures. The signature has multiple pages, front and back. Then the signature is cut and folded and bound. If the number of pages of text is equal to the number of pages on the signature, everything is fine. Otherwise you end up with a few blank pages. It’s not worth it to try to fish those blanks out of the stack, so they just get folded and bound with the rest of the pages."
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7wwdjf | How can old games be put into resolutions like 4K and 1080p or maxed at 60fps? | I've watched a few videos of people playing games like Goldeneye on emulators at full HD at 60fps, which I know the N64 was not capable of. So how is it done? | Technology | explainlikeimfive | {
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"Imagine I describe to you how to paint the flag of France: * Paint a blue band that covers the left third of the canvas. * Paint a white band that covers the middle third of the canvas. * Paint a red band that covers the right third of the canvas. I don't need to know how large your canvas is when I give these instructions to you. In fact, these instructions are valid regardless of whether you have a small canvas or a very big one! When an emulator renders an old video game at a high resolution, it is essentially just following the old instructions, but painting on a larger canvas.",
"Important to note that just because emulators can render games at fhd and uhd resolution, does not mean it looks great. Edges do become sharper, so games with lot of geometry will look better. But textures are stretched and scaled up so much that they will look out of place in otherwise sharp world. I've tried a PC Quake 2 build recently that runs at 1080p with amazingly good detail. But that's because it has modified textures and light effects.",
"3D games are environments described with 3d object of geometrical data often reduce to triangles. Then calculation are done to create the representation as a 2D images. The code in principle have the resolution as a a set value. So it can be instructed to create a image of 640x480 of that model. You could change the values to say create a image of 3840x2160 it take longer time because there are more pixels but the emulator is faster then the original so it can calculate it fast enough. You can the same way set the resolution of a PC game to almost any resolution larger then the one they support. The frequency is likely also a variable or something similar. The ringsignal game worked in both 30 Hz NTSC and 25 Hz PAL so the code for how fast thing moves are likely independent of the frustrate of the screen. I tried to look for the game online and found that there are a GoldenEye: Source game that is new implementation of the game for multiplayer. So that could be the other alternative it if was not the original emulated."
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7wwtx7 | What exactly is Firefox's Webrender? | I've been hearing stuff about it on reddit (specifically r/firefox) and since I can't find any simple explainations about it I was hoping someone could break it down to me. What exactly is Webrender? What makes it so good? And will it push firefox past chromium when all the bugs etc. are fixed and optimized? | Technology | explainlikeimfive | {
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"The idea is to use the GPU(graphics card) more in the creation of what you see on the screen from the html code. How it is done can be in part explained at URL_0 The reson to do it is to render web pages faster with less CPU usage. In most case when you can code a program to use the GPU instead of the CPU for something it will be significantly faster. The problem is that it is harder to do and all types of problem are not suited to run on a GPU."
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7wzxp7 | How do missile lock and missile lock detection work? | Technology | explainlikeimfive | {
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"For the aggressor the pilot orders the missile to start seeking a target. This sets the IR tracker in the missile to look for heat signatures with-in its view. If it finds a heat source it will lock the seeker head onto that target and set off the 'growl' that you hear in the cockpit. As for the detection system, there maybe systems that just detect that an aircraft is behind you and alert to that, but the IR is a passive system and it doesn't use active seeking and therefore won't be detectable on the target. There are launch detection systems, that will alert the pilot when a missile is launched, defensive measures for IR missiles are flares or active counter-measure like laser systems that lock onto the missile and then try to burn out the IR detection using the laser."
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7x1hm1 | What's an Afterburner? How does it work? | Technology | explainlikeimfive | {
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"An afterburner dumps fuel into the hot exhaust from a jet engine. This results in significantly more power from the same size engine, but isn't fuel efficient. This makes it useful for fighter jets that want small super powerful engines but don't care about fuel costs, but terrible for commercial jets that want to operate as cheaply as possible",
"A jet engine functions by sucking in air, compressing it, adding fuel, and then igniting the fuel to cause the air to heat up and be expelled at a much higher velocity. This cycle doesn't burn all the oxygen in the air, however. An afterburner injects additional fuel into the jet exhaust and re-ignites it, increasing the exhaust velocity even further. In order to get that second combustion cycle, the afterburner has to add a lot more fuel than the jet uses, so running with the afterburner on is much less fuel efficient. As a result, most afterburners are controlled by the pilot and only used when necessary, like during takeoff on short runways."
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7x29ok | Machine learning calculations and Nvidia Volta Tensor Cores | I'm reading about Nvidia Volta and machine learning for a project I'm doing and I don't really understand what they're talking about when it comes to Tensor Cores. The [paragraph]( URL_0 ) "what are tensor cores" is what I'm referring to. & nbsp; Edit: More specifically, I don't understand what "matrix" is. | Technology | explainlikeimfive | {
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"This paragraph? > Each Tensor Core provides a 4x4x4 matrix processing array which performs the operation D = A * B + C, where A, B, C and D are 4×4 matrices as Figure 1 shows. The matrix multiply inputs A and B are FP16 matrices, while the accumulation matrices C and D may be FP16 or FP32 matrices. A 'matrix' is just a set of numbers, normally arranged in rows and columns. As long as you adhere to some restrictions, you can treat matrices almost like they were single values. For example, let's say I want to add 1 + 2, 3 + 4, 5 + 6 and 7 + 8. I can write them as two matrices: 1 3 2 4 5 7 6 8 or [1,3;5,7] + [2,4;6,8] where the sum is [3,7;11,15] - just like you'd expect. Multiply is a bit trickier and there are some special rules, but the basic premise is \"multiply everything by everything and add it all up\". What matrices allow us to do is express a large number of similar mathematical operations in a compact - and parallel - form. Consider a single layer in a neural network. You have some n inputs and m weights that are being processed in a series of functions like: out0 = i0 * w0,0 + i0 * w0,1 + ... + i0 * w0,m ... outn = in * wn,0 + in * wn,1 + ... + in * wn,m That whole mess can be represented by the multiply-and-accumulate matrices Nvidia is talking about."
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7x3tsi | what does resetting a router actually do and why is that the most common internet fix? | Technology | explainlikeimfive | {
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"Your in-home router usually does a few separate jobs. First, it literally routes data: from one computer to another in your local network, and between your local network and your ISP's network (and on to the internet). Second, it provides local network devices with their local IP addresses. Third, it acts as a Domain Name System server, helping local computers match names (like URL_0 ) with IP addresses (151.101.1.140). To do all of that it needs to acquire and maintain its own IP address on the ISP network, and then maintain various tables in memory where all that data is stored. When you restart your router, you cause it to wipe out its copies of existing data and restart its connection to the ISP network. This can fix several different kinds of problems, which is why rebooting your router seems like a magic fix to lots of network problems.",
"A router is more or less a very limited purpose, specialized computer. Much like resetting a computer may fix things by starting things over from scratch, resetting a router will make the router start up from scratch, reload its operating system, reconnect to your modem, and force all devices that were connected to it to re-establish its connection with the modem. Basically, it's just a quick and dirty way to start everything over from scratch.",
"running for a long time, the lists maintained by the router get messed up. by cycling the router off and on again, they are cleared. There are many lists for phones and computers connected 'inside' and their handles (IP addresses) and 'outside' (internet) youre connecting to to retrieve websites. This is DNS routing. On the internet, there are a lot of computers shouting \"ARE YOU THERE?\", its called Pinging. Pings can be used to find a computer, and many shady people ping accross random addresses to find open computers they can attack. This can fill the lists or by extension the routers memory over time and once its full, the device trips over itself and cant find anything anymore."
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7x4lyx | What does "living closer" to a game's server actually mean? E.g. USE, USW, EU, OCE | Technology | explainlikeimfive | {
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"Your \"ping\" that is sometimes reported is the total milliseconds it takes for your network traffic to go round trip to and from the server. Essentially, if your ping is 60 milliseconds, that's how long it takes for your computer to tell the server \"Hey I'm shooting at that guy!\" and for the server to respond \"Yes! You shot that guy and now I'm telling everyone else on the server you shot that guy!\" Its a little more complex in reality (there's some prediction and other \"lag\" reduction strategies in play) but that's the gist. Every action you perform needs to be propagated to the server... the server adjudicates whether your actions impacted anyone else, the scenery, that horse you're trying to get on, then sends the results to everyone connected. The lower that round trip, the more responsive, crisp and jerkiness free your game experience will be. If you're gaming late at night in your time zone, and you can't find a populated server to play on, decide to try a server on the other side of the earth, you may find that while playable, there's jerks, skips, lags in the action etc. Thats because your data has to go all the way to japan or wherever and back. Some of that traffice just plain gets lost and all of a sudden you glitch a few feet in game.",
"It means there is less physical cabling that your signal has to go through to reach the server and vice versa. This will mean there is less lag (or at least potential lag) as the signal gets there faster and has less degradation in its travel."
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7x5bym | What "hashing" a password means and why it is hard to decrypt them | Technology | explainlikeimfive | {
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"Have you ever had corned beef hash? Imagine trying to back calculate a cow.",
"Hashing a password is basically like dumping a strawberry (the original password) in a blender with a bunch of other fruits and then using the mush as the new password. Trying to identify (decrypt) the original strawberry in the mush of bananas, yogurt, blackberries, blueberries is going to be pretty dang hard.",
"Hashing is different from encryption because it is designed to be one-way with no way for anyone to reverse the process. Encryption needs to be reversible. Every time you enter your password it is hashed and it's the hash that is forwarded for comparison with the stored hash in your account details. Ideally the password itself should never leave your local device and should not be known or stored by the service you're logging in to.",
"As a simple analogy: take the square root of an arbitrary number, and discard everything but the 2nd through 6th decimal places. The result of the above is largely meaningless in the sense that there is next to no way to obtain the input of the function without trying many examples from a virtually infinite set of possible inputs. At the same time, there are only a few possible inputs that would return the same string of numbers[ideally one, but the example function I made up is pretty prone to 'collisions' (multiple inputs can have the same output)] ."
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7x673e | How do Captchas work? | Technology | explainlikeimfive | {
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"They are theoretically unreadable by Bots, so answering them proves you are not a Bot. This is important because there is something that hackers do called Brute Force. It basically sets a Bot(a kind of program) to keep trying a numerous lists of passwords, that is why after many tries to guess that old password of yours the captcha appears"
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7x8n3n | Why do Lithium Ion batteries lose their ability to maintain charge after many cycles of charging? | Is this due to a chemical reaction? Perhaps Lithium escapes as a gas? | Technology | explainlikeimfive | {
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"It is due to several things. The most important is physical. During charging/discharging lithium atoms move from one electrode to the other. The lithium goes into tiny pores in a sponge like electrode, but when this happens the sponge swells up. Repeated swelling and shrinking eventually causes cracking and fractures in the electrode, degrading it. The other main effect is chemical reaction in the electrolyte. During charging, tiny amounts of electrolyte material undergo unwanted chemical reactions with the electrode chemicals. Eventually the electrolyte gets polluted with all the byproducts of these reactions degrading it."
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7x9s4c | What about how 80's movies look makes it that you can immediately tell it was made in the 80's? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Its everything you mentioned and more. There are technological reasons like the cameras, lenses, film, that are period specific. Then there is artistic choices such as the background, the outfits, the shots used, the pacing, the dialogue, etc that goes in trends."
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7x9tum | How can Facebook know my thoughts and conversations but not be able to tell (and suspend the account) when a Nigerian man is pretending to be a hot American girl from Denver? | Technology | explainlikeimfive | {
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"text": [
"Facebook only cares about using you to generate revenue. Apparently that Nigerian scammer is profitable somehow.",
"Like Twitter and other social media apps, it is not in Facebook's immediate self-interest to try to remove/crack down on scammers or bots. It will always be a reactionary game first off, and it also artificially infaltes their numbers and makes them look more important than they really are. And if you think they don't know the difference between a Nigerian man pretending to be a hot American girl from Denver, they likely know and have insane amounts of data to prove it is in fact a Nigerian man. But they do not and will not care about things like this. Just like how Facebook didn't care about political ads in the US being paid for by Russian rubles, they do not care about people actively scamming or catfishing on their site.",
"Is Facebook making money off you, yes. Is Facebook making money off the Nigerian man pretending to be a hot American girl from Denver, yes. There’s your answer.",
"How many of their claimed 2 billion accounts are fake? What would happen to their share price if that number came out?"
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7x9wr1 | How do electronic thermometers work? | IIRC mercury thermometers work as the liquid changes volume with temperature, what about electric ones? | Technology | explainlikeimfive | {
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"text": [
"Thermo resistors that change their resistance based on the temperature. If you know the current and the voltage you can find the resistance.",
"Cheap domestic ones use a \"thermistor\" that changes electrical resistance with temperature. For more accurate scientific work you might use a piece of platinum wire that does the same - a Platinum Resistance Thermometer. Thermocouples are also widely used in science and technology. Two different metals in contact generates a voltage that depends on the temperature. Different combinations are used for different temperature ranges. Finally, pyrometers measure the infrared radiation coming from the object and convert that to a temperature. They are good for measuring without having to contact the object."
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7xcor6 | What is the mechanism for slow sound? Or sound in a slow motion video. | So in a slow motion video you take 600 pictures in a second then in playback you show them one after the other at the rate of 60 pictures per second, thus creating the slow motion. How does this work for sound? What is the mechanism for capture and playback? In my mind, since sound is a wave the closest analog for slow video and slow sound would be to record a duration of sound and then chop it up and play the sections back with a delay in between each. Is that how it's done? Does a software fill in the gaps to make it seem continuous the same way our brain fills in the gaps of the frames of a video? Is it something else entirely? | Technology | explainlikeimfive | {
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"Destin from Smarter Every Day did a video on this not that long ago. I'd actually been curious about it, myself. URL_0 Turns out, as others mentioned, slowing down audio ends up sounding like garbage. The \"slowed down\" audio in slow motion vids is all the result of creative foley work."
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7xd61j | Fog computing vs Mist computing vs Edge computing | Hey there. Anybody able to describe in ELI5 way those 3 concepts along with examples and connections between them? Thank you in advance! | Technology | explainlikeimfive | {
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"These concepts aren't too difficult to understand once broken down to their basics. Note, everyone views these definitions as being something different. Edge Computing: This is when you put compute resources at the edge of your network. The purpose of edge computing in IoT is typically to consolidate data from inside the network and to do some basic formatting or numbers crunching so it can be sent to a cloud based service. But, edge computing is a general term for compute that is done at the edge of a network for basically any reason. For example, edge compute can be hosting a website outside your local network for security purposes. But, in the IoT realm it is generally used to crunch data from IoT devices before sending it to the cloud. Fog computing: Often used interchangeably with Edge computing when discussing IoT. An example of this is having a lot of building sensors like oxygen sensors, occupancy sensors, temperature sensors, etc. These devices are often lightweight and speak in their own languages. In order to make sense of everything these devices may stream telemetry data to a fog computing node which takes all their data, crunches it, then normalizes it into a standardized format (like XML) to be sent to a cloud service which can then take action on it and present you with the data from many sites in one cloud location. The fog compute (or IoT gateway) does a lot of things including reducing overhead for cloud resources and conserving network bandwidth. Mist computing: Takes the whole thing one step further and presumes that the IoT sensors/devices themselves can provide some computation and normalizing of their own data. This helps offload the compute requirements of an IoT gateway. The idea behind this is that if you spread the compute load out then you'll have more compute at the edge and will be less reliant upon a cloud. And in theory you can make local decisions without the need of a cloud. Such as taking occupancy sensor data, normalizing and crunching it with temperature data and making predictive adjustments to an HVAC system without using the power of cloud computing. You'll likely still use cloud computing for aggregation of data among many sites, but the independent sites may be able to make local decisions without the requirement of a cloud. It's essentially the next generation Fog computing. Keep in mind these terms are still fairly new and everyone has a different definition of what they actually mean. But, this is a good starting point. Just keep in mind when you search that people trying to market or sell their product will latch on to buzzwords and they'll all be slightly different and may stretch the definitions of what they actually do and the terms they use. The long and short of it is Edge computing is any compute that is done at the edge of a network. Fog computing is consolidating data at the edge of a network (typically in an IoT gateway) and utilizing cloud based compute for extended purposes. Mist computing is using smart IoT devices that take some of the overhead away from IoT gateways and allows for more local control/access of the data for action to be taken."
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7xd66a | How does Machine Learning (ML) allow one to teach a computer simply by providing it with sample data? | Technology | explainlikeimfive | {
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"The sample data contains examples of inputs and correct outputs. Feeding many thousands of such examples through a learning system enables it to extract the abstract links between the input and output and basically \"learn principles\". That in turn enables it to make correct guesses when an entirely new input is presented to it. The general abstract links it learned are applied and it balances whether this new input is \"correct\" or not. This can take many forms internally, sometimes the abstract links between input and output is explicit and sometimes it's a lot more opaque (like with neural networks, where it's hard to exactly see _why_ a trained neural network works).",
"Here's an example. Say you want to make software that can read hand-written letters and numbers. Everyone's style is a bit different, so what you do is set up a system that looks at an individual letter, runs it through a system of simulated weighted nodes depending on what different sub-regions of an optical sensor reads, and it outputs a value of the letter it computes as the closest. With no training, there's no way to discern what anything is, so you come up with a whole bunch of samples and the expected output. When the computed output doesn't match the expected, it changes the weighted nodes to accommodate the new data. Feed it through all sorts of styles of writing, and repeat with all letters until all the computed outputs match the expected ones. At this point, your computer has now learned how to read hand-written writing via machine learning. There are other examples too, but they all follow the same logic. You provide a bunch of sample data along with the expected output for that data or at least some way to evaluate the output, allowing the output of what is good or bad feed back on itself to improve the output."
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7xehu9 | Why do things always look farther away on a camera? | Technology | explainlikeimfive | {
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"It basically all depends on the lens you're using. Most cameras that we use, such as those on cell phones, have a relatively wide field of view. The wider your lens, the further away the subject will appear. The opposite is also true, where a much less wide angle lens, or a telephoto, will make the subject appear closer to the photographer. Source: am photographer",
"It could be because of the distortion of the lens, or the focal length. A wide angle lens will have a low focal length, and will get a lot in the picture, but objects will be distorted around the edge, and look distant. A telephoto lens will get less in the shot but get really close to an object.",
"If you're using a phone, it's because the lens has a wide field of view. Some lenses have the opposite effect.",
"Avast ye! Yer not alone in askin', and kind strangers have explained: 1. [ELI5: Why do cameras on 0x zoom produce images that seem further away than what you see? ]( URL_3 ) ^(_12 comments_) 1. [ELI5: Why, when I take a picture, does it appear further away in the image than when Im just looking through my eyes? ]( URL_4 ) ^(_1 comment_) 1. [ELI5: why do things look so much farther away on my cell phone camera in comparison to my eyes? ]( URL_5 ) ^(_2 comments_) 1. [ELI5: Why does object in camera look smaller than it does with our own eyes? ]( URL_0 ) ^(_2 comments_) 1. [ELI5: Why do phone cameras (for example) make close objects appear much further than they really are when compared to the naked eye? ]( URL_1 ) ^(_11 comments_) 1. [Why do pictures of the moon look smaller and zoomed out on your phone compared to in person. ]( URL_2 ) ^(_6 comments_)",
"Different lenses have a different focal length. Higher the length, the more magnified what you see is and the narrower your field of view (think: tunnel vision). On a high end camera or old film Camera, 50millimeter focal length is very similar to what we see. Anything lower is wider, and really low, say around 10mm or so, and you start having such a wide field of view you get the fisheye effect. 300, 400, even 500 mm give you that look you see in tight shots of NFL players for example. Also, the longer your focal length, the closer two objects appear to each other. It's called compression of distance. A really cool example fan be found by searching for 'moonwalk vimeo' (not a typo, it's on Vimeo). it's a clip of a dude walking on a slack line with the moon behind him, shot from a mile away, with a focal length of essentially 1600mm. Moon is amazingly huge. Also, search on Vimeo for 'behind the glass' - a series of great videos explaining some more cool things about lenses in some pretty ELI5 and dad jokeish terms.",
"Photographer here. I think all the answers miss the spirit of the answer, although they're all correct. Other commenters mention how camera lenses work, but the human visual system has an amazing ability to focus on a distant object, while maintaining visual awareness of the overall space. This is because the eye has a small area of high resolution, low res peripheral vision, but the ability to track onto anything of interest in a fraction of a second with the central vision. If you're photographing something distant, you have to use a telephoto lens, or it will be tiny in the photo; that lens cuts out most of your surroundings. In person, you have a detailed view of both the distant object and your immediate surroundings, you just don't think about the movements of the eye and head that make it possible to perceive both at once.",
"Great question. Lets just say that to approximate the human eye, you need a 35mm film camera and a 50mm focal length lens, or a 35mm lens, and a much smaller film area (like a digital camera) When looking through a 35mm camera, with a 50mm lens, and taking pictures with it, objects on the film will appear as large as they are in real life, because that combination of lens and film ahs the same light angle/zoom as the human eye. Neither zoomed in or out, just right, just how we see the world. You're familiar with wide angle and zoom lenses I'm sure. Have you ever thought about the fact that the human eye has a lens, and therefor it has a zoom we would call a focal length? Long focal lengths magnify an image and zoom it in, but you lose the sides of what you're looking at, like looking through a toilet roll. Short focal lengths have a very wide angle that captures everything, but distorts straight lines and makes everything small. The focal length is just one part of it but it's the easiest to understand. The size of the film, or sensor, or retina in the eye, combined with the focal length of the lens, results in a ratio you might think of as a zoom. A zoom lens on a small sensor/film/retina would just be a normal lens, neither zoomed in or out on a much larger sensor/film/retina. Most digital cameras have TINY sensors, much smaller than our retina, or a 35mm film section. This tends to make everything in them appear zoomed in. For instance you have to stand MUCH farther back from what you're taking a picture of, in order to fit everything in the frame. So many phones and portable cameras have a lens that tries to have a wide angle. It helps make it more like a human eye, but in actuality most cameras zoom in even at wide angle, so in spite of thinking it makes the images look smaller, it's actually zooming in on them. In order to truly make objects in a photo appear much smaller than real life, you'd need a very large image sensor/retina/film area with a short focal length lens, which would be like a fisheye lens and very distorted. The 360 panorama cameras actually use 2 such lenses back to back to capture all around images, and they remove the distortion by zooming into the images to make them look more normal, allowing you to pan and tilt the image to look around. If you printed one out on paper, it would look hopelessly distorted, like looking at your face on a christmas ornament."
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"https://www.reddit.com/r/explainlikeimfive/comments/6viwvc/eli5_why_do_phone_cameras_for_example_make_close/",
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"https://www.reddit.com/r/explainlikeimfive/comments/1fr8p7/eli5_why_do_things_look_so_much_farther_away_on/"
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7xeinv | Can someone please explain the logistics behind 2nd day shipping versus overnight shipping? | I send out a lot of packages for my company and noticed there is a dramatic drop in the price for sending something 2nd day vs overnight. For example, from Baton Rouge, La. to San Jose, Ca. will cost $80 overnight vs $35 2nd day. Why can the 2 day be offered for so much cheaper when the package essentially takes the same route? Where is that package sitting for the extra day? | Technology | explainlikeimfive | {
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"It comes down to speed and bottlenecks. If a package can wait a few days before being delivered, it can take its time. If it has to take a particular flight, and that one is over loaded, it can just wait. Packages can build up for a day or so and then be sent in one large flight instead of several smaller ones. If it hits a bottleneck, it can wait until it resolves itself. A two day package has extra time for those delays to run their course. An overnight package needs every leg of the journey to work quickly and smoothly.",
"the price is higher because it's more profitable. the carrier just lets the package sit at one of the distribution centers because it knows the package can wait, so it has time to deal with ther 10,000 other packages that are either overnight, or ground deliveries on their 4th or 5th day. shipping carrier has a Service Level Agreement deadline of 2nd day. it doesn't have to deliver it overnight to meet the agreement so it doesn't."
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7xf3om | Why do developers make the recoil in video games like CS:GO and Fortnite not go directly in the middle of the crosshair? Why do they spray around the crosshair instead? | Probably not the usual ELI5 post :/ | Technology | explainlikeimfive | {
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"because real gun recoil goes all around, not in just one axis. it depends on many chaotic variable like where the buttstock is on your shoulder the moment the recoil force is transferred into your body.",
"Well, CS: GO is descended from an almost 20 year old Half-Life mod where that was a restriction / feature of the engine, and it's been a staple through each iteration of the game since then. I can't speak to Fortnite specifically, but I can only imagine it's because associating the camera with the recoil would cause for a very disorienting experience, or at least a confusing one if the crosshair were tracking all over the screen.",
"When you shoot real guns the recoil will pull the gun to one side or the other. This is dependent on the gun, your grip, your stance and some other factors. To replicate this games make the recoil more chaotic instead of just up and down. Also from a game balancing perspective, having completely vertical recoil would mean everyone would be getting head shots by just aiming anywhere on the body and waiting for the recoil to bring you up to head level. Then there would be no real consequence to full auto fire.",
"making the crosshair move with recoil would suck, because while it encourages proper recoil control each individual bullet would move the crosshair in an excessive way and due to the standard fixed crosshair that almost every fps game has that would mean your screen shifts with your crosshair.for example the Ak47 (csgo) is one of the hardest sprays to learn due to the massive recoil that it has, and if each individual bullet were to move the screen with it, you could not shoot half the clip before your screen was filled with sky. however if the screen were stable while the crosshair was dynamic this would be a different case as the constant shift in cross hair would be really tilting might seem to hard, without a way to test this we cannot say for certain and this might even be better as it could make recoil easier to learn , developers might implement this in future games but it is unlikely as this is just the traditional way to make fps games and straying from the formula might kill your game"
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7xfbb6 | How does facial recognition recognize me when my face is bruised/swollen? | I tried searching but couldn't find a specific answer. I fell on the ice like an idiot and yesterday and busted up my teeth, lip and nose. I have a big spot of road rash (for lack of a better term) on the left side of my lip, it's very swollen, black eye, and my nose is a little cut up/swollen. Yet my laptop had no problem recognizing me. How does this work? | Technology | explainlikeimfive | {
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"Facial recognition uses measurements of parts of your face that don’t move. Like the corners of your eyes, the point of the nose, distance between nostrils, and the angles between these points. Swelling is unlikely to cause errors, a broken nose that isn’t reset will. If you google facial recognition images you’ll see a lot of line maps overlaid. Your like map is what the system is comparing to its records."
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7xfhvg | - Why when watching HD movies is the dialogue volume so low and the background noises (score, explosions, etc) so loud? | Technology | explainlikeimfive | {
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"Having a high dynamic range (the difference in volume at reference amplification between the lowest whisper sound and the loudest explosion in the soundtrack) is often a sought after factor. In proper professional movie theatres where you won't bother a neighbour this is a good thing. For most consumers it's pretty annoying. If you're able to, when I set up my surround sound I program the center channel at least 3db louder than any other speaker to compensate for the quiet voice thing. Many receiver/amps have also a night mode that compresses Dynamic range as well although I haven't been a fan when I've tried it.",
"You need at least a 5.1 surround system and equalize the center channel with the others. Dialogue is usually in the center channel, so it's volume should be increased relative to the other channels",
"I experience it just out of TV speakers. Literally can't watch a damn thing without having it super loud. I used to have a htpc plugged into my TV and windows has an audio setting called Loud Equilization which completely fixed it, but can't replicate it on other devices. I now just have an Android box connected to the TV and been trying to find and equivalent setting. Unless I wear headphones, as soon as music or an action scene plays in the show, wife comes out 'can you turn that down a bit please', at which point I just switch the TV off because it's fucking pointless.",
"Can fix that with VLC player it's simple to do URL_0",
"To add to what others are saying, and it hasn't been specifically mentioned so far, is that filmmakers set out *deliberately* to create the huge gap between dialogue and explosions. In sound editing there are a few standards (like LUFS) that define peak waveforms in dB. It's standard practice in the industry, intended to be viewed in theatres.",
"Make sure you're using the correct audio settings for your setup. If you have 5 speakers and 1 subwoofer, you have a 5.1 system. In that case, you'll want to boost your center channel volume by a decibel or two at a time until it feels right. You may also have a calibration option in your audio receiver; if so, I recommend trying that first. If you only have two speakers, make sure your player and receiver are set to 2.0 or dual-channel audio. If they're set to 5.1 and you don't have that setup, you're unable to hear 4 channels of audio that the video player thinks you have. One of those channels is the center channel, which is commonly used for voice. Once you're using the correct settings, voice should be much closer to the score and action scenes in movies. If it's still significantly quieter, you can try setting your audio to \"mono\" (last resort, you'll lose audio directionality) or try one of the other suggestions here; the above scenarios are just the most common I've seen.",
"I've never noticed this but it's probably because I always watch everything with the subtitles on. That way is someone is doing the dishes or cooking or something I don't have to rewind or miss anything. It does suck with comedies because it screws up the timing of the jokes, but other then that I love it. I've been doing it since high school and now am just used to it. It sometimes bugs other people (roommates, parents) but they are usually polite and let me do it and then eventually get used to it.",
"Here's my question. Compressors are super simple. Maybe the answer is processor speed but why in the hell do 5.1 systems not have good compressors? I've even got dynamic EQ and automatic volume automation (not a compressor) in my recording software. These things will work in real time on software monitored tracks with no noticeable (eh, within reason) latency. Besides, how hard could it possibly be to delay the picture by the same amount of time the latency of such processing would introduce to the sound? I have a Night Time setting on my Boston Audio system that does nothing but bump the vocal range in the eq. Compressors damn it! We want compressors!",
"Looking at you The Walking Dead! If there wasn't subtitles I wouldn't know what's being said and my speakers would be blown the second anything action like would happen",
"Nothing to do with HD stuff. This has been an issue since the VHS days(Though rarer back then. I had some tapes that did this). It's to do with the sound mixing. TV has this problem a lot, even when it's got nothing to do with surround sound and stuff(I was playing volume jockey in the 90s a lot when watching cable TV). So do many net videos.",
"I'd double check that surround sound signals are actually reaching your receiver. If you run it through your tv, then to your receiver, the tv may be stripping it down to PCM (2.0 channels) due to fears of copyright protection, then your receiver is emulating PCM back into surround, creating the problem you're describing. Using all HDMI with the ARC (audio return channel) function shouldn't strip it down, but it still may if it doesn't pass the HDCP (high definition copy protection) check. Try running either optical or digital out from your player directly to your receiver, and check that the receiver options are set to Dolby, not just \"all speakers\", which is a fancy form of stereo 2.1. Hopefully that will correct your issue!"
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7xgezx | question about 2pac hologram. | Technology | explainlikeimfive | {
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"The \"hologram\" was actually just a modern version of an old stage illusion called [Pepper's Ghost]( URL_0 ). An angled transparent reflector (in this case a thin sheet of mylar) was used to make a projection coming from one angle look like it was sharing the same stage visible from another angle. & nbsp; The visuals were computer generated images done by special effects company Digital Domain, who typically work on big Hollywood blockbusters. They're the special effects house that de-aged Jeff Bridges for Tron: Legacy, and making a new stage performance for Tupac would involve roughly the same techniques. & nbsp; I don't know how much of the audio was previously recorded tracks and how much was done with a sound-alike voice actor, but it's probably safe to say there was at least a little of both."
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7xihcy | difference between iPhone jailbreaking and Android rooting | Technology | explainlikeimfive | {
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"As said before there's no real difference. Just like you have multiple accounts on a computer with different access levels that is true on your phone as well. Think of it as the difference between a customer at a store who has no keys to access restricted areas, your supervisor who has a key to the office and the back room, the janitor who has most of the keys but not necessarily all of them, and the manager who has a master key that works everywhere and the code to the safe. Each person has different levels of access. The default phone user account is like the janitor, you can do basically everything but there are still some things you're locked out from. So when you root or jailbreak your phone you're simply changing your access level to that of the manager. You give yourself access to every part of the phone and full control. There's various ways to accomplish giving yourself access at this level, most involve exploiting the software in some way, which is usually why it's frowned upon. This is also why the ability to do it is dependent on the operating system version your phone is running and the manufacturer of that OS. For Android each manufacturer has a custom version of Android, and patches the exploits on their own time. This means that different phones are easier to root. For Apple they tend to crack down on it more so they patch the exploits as quick as they can. You're perfectly in your right to do it to both your Android or your Apple phones. There's no legal action that the phone manufacturer could take because you own the phone. They can however make it void the warranty (if they can detect that it's been rooted or jailbroken) or refuse to service it. Samsung for instance won't work on any phone that has tripped their security software Knox, and rooting your phone does that. Edit: word choice correction",
"Rooting and Jailbreaking are the same thing. What your doing is accessing the root user account. The difference is Android doesn't prohibit rooting. Apple does. Apple does this because just like with all their products, they don't trust the user to be secure. They control the hardware, OS, and software you use.",
"It's worth noting that until very recently, Windows allowed root access by default. This contributed a great deal to Windows' reputation as being virus-ridden. Most users really do need protection from themselves.",
"Jailbreaking bypasses code signing restrictions and allows you to execute \"unauthorized\" code. Root gives you full top level administrative access to the device so you can modify anything you want."
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