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7p2hbd | Why do old light gun video game accessories (like the NES Zapper) not work on modern TVs? | Technology | explainlikeimfive | {
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"CRTs would turn off the pixels and then light them up again each frame, lighting them up one by one in sequence. By timing when the light gun \"sees\" the pixel light up, it can deduce where the gun was pointing. Plasma/LCD/LED screens are permanently on, they just adjust the pixels each refresh. There is no \"off\" state (unless the screen is actually off). The mechanism which the light guns used on CRTs simply does not exist.",
"CRTs are a glass wall of phosphorus that is lit from behind by a raybeam of electrons. The ray sweeps horizontally across the screen row by row, lighting up the phosphorus where required to make the picture. It does this 50 or 60 times a second depending where you are from. The NES knows what time the ray started the top row and measures the time it takes to see it with the gun. This then gives the location on the screen. Plasmas are essentially a huge matrix of single pixel CRTs so they don't scan. LCDs are basically curtains hiding a back light source so they don't scan either. Because neither scan, the NES can't calculate the location from when the new frame starts drawing."
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7p650d | Why do most cameras have a lower limit for ISO that is ISO100? | I know some cameras have limits that are lower like ISO50, but why is there a lower limit to ISO in the first place, as it's just an amplification of the electric signal coming from the sensor? | Technology | explainlikeimfive | {
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"The signal coming off the sensor has a certain noise figure. The ISO setting adjusts how much this signal is amplified before being digitised but there's a limit in the range of this amplification. If you allowed, a minimum setting of say, ISO50 instead of ISO100, that would increase the amount of noise being digitised at any given high ISO setting. It's more important to maximise high ISO performance since you can always achieve the same effect as low ISO with ND filters."
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7p77hv | When coming to a stop in a vehicle while listening to FM radio, why is it that if the reception isn’t clear, pulling forward about a foot fixes it? | Technology | explainlikeimfive | {
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"FM radio suffers from *multipath interference* in which the signal bounces off of buildings and other objects, reflecting back and interfering with itself. These spots of interference can be quite localized, so a small motion can move you in and out of them."
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7p839x | how bionic limbs work? How is their body able to tell the limb to move? | Technology | explainlikeimfive | {
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"Yo ho ho! Yer not alone in askin', and kind strangers have explained: 1. [ELI5: How do mind-controlled prosthetics actually work? And how do they \"feel\" when worn? ]( URL_0 ) ^(_8 comments_) 1. [ELI5: How are prosthetic hands controlled? ]( URL_3 ) ^(_13 comments_) 1. [ELI5: How do moveable prosthetics work? ]( URL_4 ) ^(_2 comments_) 1. [ELI5: How can you control bionic body parts with your mind? ]( URL_1 ) ^(_6 comments_) 1. [ELI5: With the current knowledge of bionic thought-driven limbs, why do persons like Steven Hawking not participate in this? ]( URL_2 ) ^(_2 comments_)",
"Firstly, the intended movement can sometimes be determined from movement of other muscles, as u/Rigaudon21 points out. Try quickly curling your index finger, and notice how your entire arm moves from the elbow down. We also have a fairly good understanding of how nerves work. That means we can actually create neural interfaces that interpret the commands coming from the brain through the nerves and direct the bionic limb to carry out the instructions. This is still very much in development, but shows a lot of promise for more precise and effective control compared to the first way."
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7p8yz8 | What is the difference between 3GB on a hardrive and 3GB on a Graphicscard? | And why is there a huge price difference? | Technology | explainlikeimfive | {
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"Graphics cards store data in ultra-high-speed silicon memory chips. Those are costly. Hard drives store data in very-low-speed magnetic recording media, which is read and written by moving devices with electric motors. This is cheap but 10,000 times slower.",
"The gigabytes in a hard disk are for permanent storage. You save files onto them that will still be there after you've turned the computer off. The gigabytes on a graphics card refers to the amount of RAM it has. RAM is for temporarily storing the data it is using at that time. The data doesn't persist when the power is off. The RAM on a graphics card is used for storing things like textures, models and other graphics related data. There is a huge price difference because they are entirely different things, for different purposes, using different technology.",
"It's a different kind of storage. The storage on a graphics card is more like RAM than it is like hard drive space. The memory on a GPU is meant to do more work faster. The type of connection it has to the processor means the data will travel back and forth from the GPU memory much faster than it would from a hard drive.",
"Hard Drive = Size of Trunk/Gas tank. RAM/Processor = Engine size/Horsepower. Yes, this is an oversimplification.",
"Different memory technologies have different speeds. In general, more speedy memory is also more complex, and thus more expensive. So memory in computers are tiered. Generally, the faster your memory is, the more expensive it is, so you use less of it, but in tiers closer to the CPU. This is roughly how it goes: 1. there is a very, very fast but also relatively small memory directly built into the CPU. Adding more becomes just too expensive as you are putting it directly into your CPU. This is the L1 cache and usually only a few kb, but this is what the CPU works with. 2. then you might have another of these caches on the motherboard, again, it is bigger but a bit slower, but also a bit cheaper. These are the L2 and L3 chaches, where data from your RAM is stored until it can go into the CPU. Makers of CPUs and boards carefull plan it that the L3 cache can feed the L2 and that the L1 so no delays happen. 3. at one point you arrive at the RAM which feeds your caches. Today that is typically 4 GB to 16 GB. This one is pretty fast, and comes in reasonable sizes. Servers, workstations etc might sport up to some 64 GB or more RAM. You have a bandwith of some 10 to 20ish GB/s with modern DDR3 RAM, and access times in the range of nanoseconds (billonths of a second). 4. then you might have a fast SSD for your windows partition and the pagefile, which is basically an extension of your RAM, just on your disk. Typical SSDs today are in the range of 128 to 512 GB. You can get 1 TB SSDs for some \"reasonable\" price today. You have a bandwidth of some 300 MB/s or up to 2000ish MB/s and access times in the area of some < 100 microseconds (millionths of a second). 5. for large storage you use normal spinning disks, HDDs. Those are slower, but you can easily afford a few TB if you want to. Servers can sport some 100s of TB for \"reasonable\" cost. The throughput is some ten-ish MB/s, access times are in the range of 5,000 to 10,000 microseconds (so thousands of a second), so they are much slower than SSDs. But again, cheaper. 6. if you want more, much more storage you can use tape drives, but they again are much slower. You can store a real lot with modern tape drives, but you might get access times measured in seconds or even minutes. Or someone needs to go to the shelf and put the tape in (in large centers, you might have a robotic arm or so that does that). Graphics memory is basically RAM that needs to be really, really fast because modern GPUs need to process a lot of high-res textures. A *real* lot, so the makers of higher tier GPUs pick the fastest memory that is industrially available, but that is also the fastest. And for the most powerful cards with the fastest memory it can happen that the memory actually is not (yet) available in sufficent quantities. The bandwith of modern graphics RAM is around 40 to 120ish GB/s, while the most recent developments (as just said: it is not even widely available for the actual demand) has a bandwidth of some 265 GB/s. Samsung currently expects the next generation (without delays in 2020) to do even twice of that. As last note: There of course is the question of volatilty. If you switch of the computer, what was in your RAM, Graphics memory and caches will be gone because these memories only work when powered. SSDs, HDDs and tapes are persistent, meaning they keep the data when they are off. So the fastest, cheapest RAM would be pretty useless to you if all in it was gone with a reboot. Yes, there are works on memory that'd be as fast as RAM but still is presistent. But those are not ready yet."
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7pa65r | Why is there no longer a satellite delay on television interviews? | Technology | explainlikeimfive | {
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"Fiber optics have permitted these to be conducted via terrestrial lines instead of by satellite."
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7paim6 | How come every time you save an image the quality becomes worse and worse. Would this still happen if you screenshot it? | Technology | explainlikeimfive | {
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"Often when you save an image (either saving it or screenshotting it) it gets stored as a compressed image file. Compression reduces the file size by averaging pixels or simply by skipping over unimportant pixels. Depending on the compression format, a lot of the image quality can be lost. Opening an already compressed file, adding text or a watermark, then compressing it again will reduce the quality further because it has to guess what the pixels used to be before.",
"This is only true if you are using a lossy compression algorithm. Lossy compression algorithms aim to reduce the space required to store a file by discarding information that is deemed unimportant. For example, JPEG stores color information with less precision because the human eye is not as sensitive to differences in color as it is to brightness. Lossy compression algorithms are used because they can deliver much higher compression ratios with little loss in quality. However, every time the image is encoded, information is lost. If you keep re-encoding the same image over and over again, you'll lose more and more information until the image is unrecognizeable. This is in contrast to lossless compression, which will encode the file in a way that (on average) uses less data, but without discarding any information. A file compressed with a lossless algorithm contains all the information needed to reconstruct the original perfectly."
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7pcqqw | How do recycling plants split paper from plastic? | Technology | explainlikeimfive | {
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"Mill manager for a recycling company checking in. Their are several ways. A lot of companies do it with physical labor. Most of the time it a negative sort which means you pull everything you don’t want in the final product. You place 10-15 people on a conveyor belt system. Their is usually some sort of magnetic conveyor belt that runs perpendicular to main conveyor belt that pulls all metal off and brings it to a separate area. Then the people on the main line sort everything else. Some people pulls PETE drink bottles, some pulls HDPE bottles, someone pulls wood, some pull cardboard, some pull boxboard(think cereal boxes)someone pulls rocks, some pulls aluminum, some pull garbage (food, dead animals, etc), some pull glass and so on. It all depends on how many different final grades they have. So what you have left is mixed paper. Newspaper, office waste, any left overs that people missed. Sometimes their is a secondary sort but it all depends on the mill specifications on what they can process through their pulper and screens. That paper is baled and sent to be made back into paper. Usually ass wipe or napkins or plates or cores (think brown part of toilet paper rolls). Everything else that was pulled off the initial sort line is baled and sent to be made into new stuff. Wood can be made into mulch or fuel wood. Aluminum is melted down and made into new cans or whatever. Their is numbers on plastic (1-7) so that it is easier to identify but it isn’t mandated by law to have a number on it so it can be a little difficult sometimes. The plastic is ground or Pelletized and made back into new products. Their are also more automated systems. They can sort with a scanner and blow different grades off at different points of the conveyor belt. The process is the same as I mentioned above. You can also run some material through at Trommel system. Pretty much the same as the machines you see on Gold Rush except not nearly as much water. It really depends on the quantity of material you need to sort. Sometimes it a combination of 1 or more ways listed above. I will definitely answer questions if anyone has them but my fingers are sore from typing on mobile. Hope that helps!! Sort line picture. URL_0"
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7ph68t | how do waterproof phones or phone cases stay waterproof but have clear speakers? | Technology | explainlikeimfive | {
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"Speakers don't let air pass through them rather they function by moving air by \"vibrating.\" So they can easily be waterproof by not allowing water to get past the cone."
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7pjvsj | Why does the Arctic not exist on Google Earth? | Technology | explainlikeimfive | {
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"The problem with the Arctic ocean is that there are no permanent ice-sheets. The Arctic ocean is partially covered in sea-ice but whilst ice can survive for multiple years, the ice itself isn't permanent and the appearance changes substantially over time, both over winter-summer cycles and between years. Generally speaking, Google Earth uses summer imagery and actively avoids temporary snow/ice cover, which is why I assume they've decided to completely ignore the Arctic ice cover and just show bathymetry. Otherwise they would have had to make an arbitrary decision about which snapshot to use for ice cover, which probably wouldn't be very helpful. It's the exact same reason why Google Earth doesn't show the sea ice around Antarctica either. Other users suggesting that it's because of a lack of mapping equipment/satellites are incorrect, whilst it's true that a lot of satellites do not cover the poles, they do still exist (fairly obviously, since Antarctica is visible at high resolution).",
"Because the arctic isn't land. It's just a region sea ice that grows and shrinks with the seasons and changes as ice moves around. There is some land in the polar region that's considered the arctic and that's all on google maps. Antarctica is an actual continent. There's land underneath the ice, and while the ice shape/size changes, the land doesn't.",
"There is no revenue benefit to mapping the arctic. Possible they didn’t bother putting the Arctic in the satellite mapping plan."
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7pkq6q | How does my TV 'translate' the signal it receives into images and sounds? | Thanks for all the responses everyone! Looks like I have a lot of reading to do and videos to watch! | Technology | explainlikeimfive | {
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"Back in the old days, CRT TVs would sweep an electron beam across the screen, line by line,, with the amplitude of the video signal translating to the intensity of the beam. Things got a little more complicated when colour was added, but it largely works in the same way. Just with a few more parts. Digital video signals are a bit different in that they're a series of 1s and 0s. With a digital LCD or OLED display, you can control each individual sub pixel with precession, with an intensity value anywhere from 0 (off/black) to 256 (full intensity). By varying the intensity of each sub pixel, you can mix red, green, and blue to make various colours. Millions in fact. A computer inside your TV or monitor processes all this data. The video signal though may not actually contain all the information the TV needs, in order to save bandwidth. So the display does some fudging that exploits limitations with human vision.",
"Video engineer here. Oh goodie! One of those rare times when my job skills are actually useful outside of work! Basically, we see the world around us because of electromagnetic radiation - y'know, light and colors and stuff? That radiation (so... light) vibrates up and down. Some colors vibrate up and down faster than others. Our TVs kind of work the same way, except the colors they see vibrate a lot slower than the colors we see. The TV has special electronics that can listen very carefully and turn these relatively slowly vibrating waves into a signal of ones and zeroes. We call this a digital signal. These ones and zeroes spell out some really fancy computer code that describes pictures, sound, and text! Then, the TV has even more whiz-bang electronics that can take that computer code, and turn it back into pictures that OUR eyes can see on its screen! It does this by shining a super-bright light behind tons of dancing little red, green, and blue color filters. Each one is like a dot on a page, and with millions of dots we can see a moving color picture! Slightly more technical: Over-the-air, satellite, and cable broadcasting all use various modulation schemes to transmit digital data over analog radio waves / RF. The receiver (be it a TV, satellite box, or cable box) has a de-modulator (aka tuner) that recovers the digital signal from the RF. This digital signal is typically an MPEG Transport Stream describing a series of discrete programs, each in turn describing audio and video streams. These streams are compressed because totally uncompressed audio and video are really really big. Like, REALLY big. Totally uncompressed typical 1080p60 RGB video (like the kind your computer might feed to your monitor) is about 3 Gigabits per second!!! You only get ~5-20 Mbps for an HD TV channel, so compression and other trickery like component video (aka YCbCr), chroma subsampling (aka 4:2:0) and gross legacy stuff like interlacing (aka 1080i vs 1080p) is absolutely required. * Video is generally compressed using MPEG-2 / H.262, MPEG-4 AVC / H.264, or MPEG-H HEVC / H.265, from oldest to newest. * Audio is usually MPEG-1 Layer 2, Dolby Digital / AC-3, or Dolby Digital Plus / E-AC-3. * Closed captions / subtitles aren't really compressed since they're small, but are stored using standards like EIA-608, EIA-708, SCTE-20, or DVB Subtitling. The TV / satellite box / cable box has special hardware and software that can decode these compressed essences into uncompressed video and audio signals, compose them into a synchronized stream, and pipe them out to your screen over HDMI (or directly, in the case of an internal tuner). Typical LCD displays have a backlight of some kind (be it a flourescent cold cathode or a matrix of LEDs) that shines through a large array of color filters, generally one red, green, and blue filter for each dot on the screen. The filters selectively darken to mix red, green, and blue for each pixel. OLEDs are sort of similar, except each pixel is a combination of tiny red, green, and blue lights that you can control the brightness of independently. So that's how that works. If you want more info, read the wiki articles on DVB and ATSC, or any of the acronyms I listed above :)",
"I mean, like every other bit of digital indignation (pun!), the signal is a string of 1s and 0s that correspond to pixel colors, pixel locations, and sound frequencies. It's all just a matter of splitting up the received commands and sending them to where they need to go(screen vs speakers).",
"Modern TVs are for most part just computers, they get the 0's and 1's over the wire and use then to switch on pixels on the LCD. Old TVs and the evolution of TVs is much more interesting, if you are interested in that, watch [Technology Connections]( URL_0 ), a great Youtube channel that goes into great detail on the evolution of analog TV, of the cameras, Color TV, shadow masks, etc., it also covers the largely forgotten mechanical TVs.",
"336 comments and none of them are 'ELI5' You know how you can mix paint colors together to form any color possible, all from the three primary colors red, green, and blue? Well light can be mixed the same way. Your TV gets a signal that tells it what colors to mix for every little tiny bit of your screen. For example, it will receive a set of three numbers (red, green, and blue) for every tiny spot (called a pixel) on the screen. It then lights the pixel up with the amount of red, green and blue that the numbers specified. Repeat this for every tiny pixel on the screen and you end up with a full picture. I think how those images are encoded and transferred isn't really what OP was after, so this is a true ELI5 of the fundamental concept of how it works.",
"At the lowest level it is all 1's and 0's, and each one is called a bit. Usually 8 bits are grouped together to form what are essentially letters, called bytes. Since there are 256 ways to arrange 8 1's and 0's, there are 256 letters in that particular alphabet. Stepping up a conceptual level, the signal is sent according to a protocol, a language written in bytes that describes video. A protocol might look something like this: < start video > < resolution=1000x1000 > // each frame will be 1000x1000 and have 1M pixels < color depth=3 > // each pixel color will be described with 3 bytes < speed=24 > // 24 fps < start frames > < frame=1 > < row=1 > (1000 x 3 bytes, representing the pixels) < row-2 > (1000 x 3 bytes) . . < row=1000 > (1000 x 3 bytes) < frame=2 > < row=1 > etc., etc. Your TV understands this protocol, it speaks the language, and knows how to turn it into a picture.",
"Good answers already, but yeah basically going all the way back to the beginning their has to be a “decoder” to display the images and speakers with a receiver/brain to decode and output the audio. 0’s and 1’s just like if I typed this message on a physical keyboard it puts my letters on the screen, how a record player/cd player interprets bumps as data. “How” the TV’s actually display the data also depends on the TVs viewing technology from CRT, DLP, LCD, Plasma, OLED, etc. Also one note since CRT was brought up, the medium which the data travel has also changed a bit from analog to digital. Likely, the input medium is also vastly different now than even 15 years ago. TLDR; inputs and outputs of data through various mediums (waves/antennae/analog/VCR tapes OR digital/Satellite/Cable/Streaming/Disc based media",
"While not an ELI5 [this video]( URL_0 ) is a great primer for digital video.",
"I think the tv eats up all the shows at the beginning of the day while you're asleep and while you're at work it's digesting everything the you come home and relax on your La-Z-Boy chair with your bowl of pretzels and a cool crisp bud light and you pick a show and your tv takes a shit and the pictures on the screen are what comes out of its butt and then the audio is the tv taking a piss butt don't know for sure I'm not a science",
"Here is a good ELI5 style answer for digital TV. Imagine a light brite, its a big grid and you full it up with colored pegs to make a picture. The signal, is basically a list of which colored pegs to use to fill the light brite up to make a picture, blue peg, top left, 6 green pegs, two red, etc.... Then, imagine you can read this list and complete it roughly 30 times every second, that would happen so quickly, you would only see the resulting picture and trick your eyes into thinking its moving."
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7pmwy5 | How do DVDs work? How does a plastic disk with a reflective side hold data that can be observed at a later date? | Technology | explainlikeimfive | {
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"It works very similar to an old record, actually. But, instead of bumps and a needle, it uses a reflector and a laser. The reflective part isn't completely solid though , but rather contains TRILLIONS of little divots that don't reflect the laser back. Thus, while spinning, the lens that reads the reflected laser beam receives a series of returns and no-returns on the light, which get interpreted as 1s and 0s, standard binary information bits. Those bits get read as video, sound, or whatever was encoded onto the disc originally."
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7pnmnu | How do PDFs get so much data into a such a small file? | Technology | explainlikeimfive | {
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"Unlike a picture which has to store color information about every single pixel, a PDF document is a container holding only the instructions needed to recreate all the parts of the newspaper. How does this work? Say you want to draw a simple line across a page, depending on the size of the page that line could be made up of hundreds of pixels each with their own set of colors, in a PDF you can instead say draw a line starting from left side and ending on the right side, make it black. This is much simpler and doesn't take room to store those two instructions. Sometimes objects are too complex to store as drawing instructions and must stored directly as a picture, in this case the PDF will use compression to reduce the picture data as much as possible.",
"PDFs are optimized for representing documents, which tend to use a few shapes (the characters in the fonts) over and over again. It only takes a short list of vectors to describe each character, and then they are reused."
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7pnx7n | Big O notation (Computer Science) | What is it and just give me whatever information you can around it please. | Technology | explainlikeimfive | {
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"When we're talking about algorithms (recipes for solving problems), we care about how fast an algorithm is. Specifically, what we often care about is how fast an algorithm can be given a big set of inputs. If you need to sort five children in order of age, the algorithm speed barely matters; but if you need to sort ten million children in order of age, then choosing the wrong algorithm can mean the difference between a runtime of a few minutes and a few days. Big O notation is a simple way of saying how an algorithm's speed is affected by the size of the input. Note that it's not a very _accurate_ measurement; it cares more about the theory and maths than it cares about things like CPU optimisations. * O(1) means the algorithm takes the same amount of time to run regardless of the size of the input. This is a bit of a holy grail, and not often attained. In some data structures, retrieving a single element is O(1). * O(log n) means the algorithm's speed drops very little as the input grows. It might mean you need to increase the input size by ten times before the algorithm's speed drops. * O(n) means the algorithm's speed is linear with the input size. Adding up a set of numbers requires you to look at each of the numbers, so adding ten thousand numbers takes ten times as long as adding a thousand numbers."
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7pocqt | If you duplicate the pixels, can you achieve the same quality at a higher resolution as the original? | If not, why? | Technology | explainlikeimfive | {
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"Depends on the interpolation you use, and what you define as \"quality\". If you use the most naive interpolation, which is basically what you describe as \"duplicating the pixels\" (which is also called Nearest Neighbor interpolation), and you define \"quality\" as the amount of non-duplicate data contained in the image, then yes, you can get the same quality at a higher resolution. Let's do a test: 100x100 image: URL_2 same image scaled to 2000x2000 using nearest neighbor: URL_0 Now you can use less naive interpolation when scaling and get arguably better results--here's the same image scaled to 2000x2000 with a more intelligent interpolation algorithm: URL_1",
"Do you mean divide each pixel into 4 of the same color? You would have a higher resolution, identical quality image."
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7poviv | why sometimes projects encourage you to check several checksums instead of just one? | Hey, so question is, most opensource projects publish several checksums for their archives (md5, sha256, sha1). Sometimes they encourage their uses to check all of those instead of just checking one. Why? | Technology | explainlikeimfive | {
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"It is possible, through some very meticulous manipulation, to create something that looks extremely similar to the original product, but has something malicious injected, and some extra stuff just to make the MD5 value match. In theory, you can also do the same for a SHA1 hash. Making something that can break both of those simultaneously? That would be incredibly tricky."
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7ppeb0 | What makes different cords/blocks charge the same phone better or worse? | Technology | explainlikeimfive | {
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"For outlet adapters, some adapters are designed to provide a larger current, but this typically increases cost/size. A few standards like USB Power Delivery and Qualcomm QuickCharge, increase the voltage with a compatible device, allowing more power (= current*voltage) to be transmitted. Apple also uses a unique method of communication with devices, while many other devices simply short the two data pins to indicate the source is a charger Many low-cost cables have a higher resistance (often by using thinner wires to save costs), which limits the current provided before the voltage drops to an unacceptable point, and some omit the data pins/wires to save costs.",
"Look on the \"block\", somewhere there should be an output listed. It's probably between 500mA and 2.5A. The higher the output, the faster it can charge. Which cable you use should matter less unless you have a very cheap, or very long, cable."
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7ppt8o | Why are cartridge based video game systems inferior to disk based ones? Also, why did cartridge based system not have load times? | Technology | explainlikeimfive | {
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"They are larger and hold less data. They are also significantly more expensive to produce. They don't have load times because there's no moving parts. It's solid state memory. No laser needing to read a disk.",
"cartridge based is not necessarily inferior in fact it's actually far superior to optical media. The data reading speeds that you can get from solid state memory is far faster than any optical drive could hope to achieve and you can even add on board memory storage for things like game saves. There are still load times just in the past (and still today in some cases for the switch) the data speeds have been so fast and the games used to require so little data that it seemed like there was no loading time. It's all about how fast the system can move data from storage into it's memory and if it can do that super fast it may seem like there's no load times. Also no moving parts basically eliminates the chance of something breaking outside of user error. The downside though is it's many times more expensive than the cost of a disc and getting the same amount of storage that say a dual layer blu ray gets(ps4 / xbox) is insanely expensive. So discs are cheap and can store large amounts of data these days and modern PC's and consoles have plenty of storage these days so it's easier just to use the cheaper medium and require the installation games these days. This saves the manufacturers money but it also helps to keep games cheaper for the consumer as well. It also means means developers don't have to try and gimp their games to make them fit on a smaller size cartridge in order to save money something that is already becoming an issue on the switch.",
"Former game developer here, Cartridge games are absolutely not inferior at all. It all depends on what you need. Cartridges are still used by Nintendo for their hand-held and mobile gaming platforms because they're not fucking morons like Sony and their total flop that was the PSP. Cartridges don't scratch, they don't rely on moving parts, or lasers, and are immune to vibration. They also take a lot less energy to operate, important for battery life. They don't have a load time because they're effectively an extension of the rest of the circuitry. You don't have to spin up the disk, move the laser into position, find the beginning of the first track, decode the partition headers, then seek to the right position of whatever track to start reading data. And any bump, you have to re-seek. Flash memory has physical address lines right to the NAND gates. If your only criteria were data density, then optical drives might be higher than flash cards. Where they do win is cost. An optical disk costs something like $0.0017 each or something, based on the last time I tried to calculate it.",
"Cartidges required a small printed circuit board for each unit they sold. The advantage it there was a direct electrical contact which enabled the data to be read much more quickly. The disadvantage is the cost to produce each cartridge. Optical media is far cheaper to produce, but the disadvantage is the read speed of your optical drive."
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7pq8nz | What are these new-age solid-state batteries? How are they different from conventional batteries? | Technology | explainlikeimfive | {
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"They're batteries that use solid electrodes or electrolytes instead of liquid. They have potentially higher energy density, and are safer since they're not flammable. They also have longer lifespans and don't produce as much heat. I think the problem at the moment is that they're not ready to be mass produced and so they're expensive."
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7pshrm | How can we use emergency calling on our phone to call 911 even when we don’t have a wireless connection or data? | Technology | explainlikeimfive | {
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"You might not have service through your own provider, but the FCC makes it a legal requirement for all providers to handle all 911 calls. That means if have ATT and are outside ATT's range, but you're in range of a Verizon tower, then your call will get connected. Apparently you can also make a 911 call from a phone that isn't even connected to a provider (meaning you can use a phone to make a call even if you're not paying for service)."
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7putbw | How do the internet clocks that our computers sync to stay so accurate? | Since a majority of the computers in the world are syncing their clocks to the internet through services like URL_1 , URL_0 , etc. how do those services maintain the time so accurately when clocks around my house lose minutes over time? Is it possible that the "internet time" could be wrong? Same thing goes for phone services like there used to be a number my parents called when I was a kid to get the time to set our clocks. | Technology | explainlikeimfive | {
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"Really really good clocks. UTC is the common standard for civil time, and is in turn based off International Atomic Time (TIA), with the difference being that UTC adds in leap seconds when needed (basically UTC is exactly 37 seconds behind TIA). TIA meanwhile is the weighted average of some 400 atomic clocks located around the world. These clock can be stupendously accurate, the losing or gaining less than a second ever million years, and some are even better than that. These atomic clocks are compared against one another and the results are usually published monthly which then sets the standard. From there various national agencies synchronize their atomic clocks to that time, usually keeping them within a few nanoseconds of one another, and they broadcast the time in some way. For something you can literally listen to, the BBC still broadcasts the pips to mark the start of the hour, which is based off an based off an atomic clock in the basement of Broadcasting House and synchronized to the MSF time signal broadcast by the National Physical Laboratory . This is fairly redundant today, but if you've ever heard [this]( URL_0 ) on a bbc broadcast, that's why. Network Time Protocol is how computers keep synchronized. You computer talks to a server that tells it the time, and those servers are split into strata based off where they get their time from. Stratum 0 is the most accurate, and will be things like atomic clocks, GPS clocks and so on. Stratum 1 tends to be primary time servers, and they'll synchronize as best as possible to Stratum 0 clocks and also cross check with each other. Stratum 2, then synchronizes to Stratum 1, Stratum 3 to Stratum 2 and so on down the line. The further down they go, the less accurate you can expect to clock to be, although the entire system is designed to try to minimize the total round trip time to keep this as small as possible. So because all (internet connected anyways) clocks are automatically synchronizing to more accurate clocks, we can usually keep things like your computer accurate to within a millisecond or so without much hassle. The clock in your house meanwhile is on it own, so if it loses time, you need to go synchronize it yourself instead of having it self correct on a regular basis.",
"In the US they are very likely updating their clock according to the time maintained by the National Institute of Standards and Technology, who have a number of super-accurate atomic clocks.",
"The short answer is better clocks. Nowadays that \"better clock\" is the [atomic clock]( URL_0 ). Mechanical clocks drift because either the devices degrade over time, or were manufactured with imperfections. On the other hand, every single atom is identical and doesn't change over time. So if you can measure the vibration of atoms, you can keep time at exactly the pace of other atomic clocks and never get fast or slow. You don't need to _build_ an atomic clock to have access to one -- the GPS satellites carry atomic clocks and constantly beam the current time down to earth. That means you can just listen to the sky from anywhere on earth and you can get a very accurate, synchronized time. Modern clock synchronization often uses a mix of atomic clocks on the ground and the signals from the GPS satellites."
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7pv7db | Why is it, when travelling at high speeds, that I lose mobile phone reception | Technology | explainlikeimfive | {
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"The phone network is made up of \"cells\" (hence the name cellphone), one signal tower represents one cell, when you move between cells one tower needs to hand your phone off to the next one, this takes a few seconds to happen. If you move too fast the towers can't switch you fast enough, the result is simply no signal."
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7pvkun | Why do mobile phones lose reception when going up/down an elevator? | Technology | explainlikeimfive | {
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"Well, your phone \"has reception\" when it can receive electromagnetic waves carrying the signal. The more energy these waves have when your phone receives them, the more reception it shows it has. These waves can pass through some materials without losing much energy; however, other materials - and I'm talking mostly metals here - will catch those waves and cause their energy to dissipate on their surface. Your phone also has a tiny piece of metal that catches the signal - it's your antenna. Now that we know these waves lose energy when passing (or trying to pass) through metalic objects, it kinda makes sense that when you're inside an elevator, which is kinda a big metal cage, the signals reaching your phone are much weaker than normally. You could also simulate that, e.g. by wrapping your phone in tinfoil, as snuggly as you can; the reception should fall down, either a bit or completely."
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7pvzmu | What does iOS do differently to Android for iPhones to only need 1-2 GB of RAM? | Edit: Should have specified; *only need 1-2 GB* compared to flagship Android models, which usually have around 6 GB. | Technology | explainlikeimfive | {
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"Eyy I actually know the answer to this one (game & app developer with low-level expertise in power and memory management - lots of iOS and Android experience and knowledge). --- Android was built to run Java applications across any processor - X86, ARM, MIPS, due to decisions made on the early days of Android's development. Android first did this via a virtual-machine (Dalvik), which is like a virtual computer layer between the actual hardware and the software (Java software in Android's case). Lots of memory was needed to manage this virtual machine and store both the Java byte-code and the processor machine-code as well as store the system needed for translating the Java byte-code into your device's processor machine-code. These days Android uses a Runtime called ART for interpreting (and compiling!) apps - which still needs to sit in a chunk of memory, but doesn't consume nearly as much RAM as the old Dalvik VM did. Android was also designed to be a multi-tasking platform with background services, so in the early days extra memory was needed for this (but it's less relevant now with iOS having background-tasks). Android is also big on the garbage-collected memory model - where apps use all the RAM they want and the OS will later free unused memory at a convenient time (when the user isn't looking at the screen is the best time to do this!). --- iOS was designed to run Objective-C applications on known hardware, which is an ARM processor. Because Apple has full control of the hardware, they could make the decision to have native machine code (No virtual machine) run directly on the processor. Everything in iOS is lighter-weight in general due to this, so the memory requirements are much lower. iOS originally didn't have background-tasks as we know them today, so in the early days it could get away with far less RAM than what Android needed. RAM is expensive, so Android devices struggled with not-enough-memory for quite a few years in the early days, with iOS devices happily using 256MB and Android devices struggling with 512MB. In iOS the memory is managed by the app, rather than a garbage collector. In the old days developers would have to use alloc and dealloc to manage their memory themselves - but now we have automatic reference counting, so there is a mini garbage collection system happening for iOS apps, but it's on an app basis and it's very lightweight and only uses memory for as long as it is actually needed (and with Swift this is even more optimised). --- **EXTRA** (for ages 5+): What does all this mean? Android's original virtual machine, Dalvik, was built in an era when the industry did not know what CPU architecture would dominate the mobile world (or if one even would). Thus it was designed for X86, ARM and MIPS with room to add future architectures as needed. The iPhone revolution resulted in the industry moving almost entirely to use the ARM architecture, so Dalvik's compatibility benefits were somewhat lost. More-so, Dalvik was quite battery intensive - once upon a time Android devices had awful battery life (less than a day) and iOS devices could last a couple of days. Android now uses a new Runtime called Android RunTime (ART). This new runtime is optimised to take advantage of the target processors as much as possible (X86, ARM, MIPS) - and it is a little harder to add new architectures. ART does a lot differently to Dalvik; it stores the translated Java byte-code as raw machine-code binary for your device. ~~This means apps actually get faster the more you use them as the system slowly translates the app to machine-code. Eventually, only the machine code needs to be stored in memory and the byte-code can be ignored (frees up a lot of RAM).~~ ([This is Dalvik, not ART]( URL_0 )). Art compiles the Java byte-code during the app install (how could I forget this? Google made such a huge deal about it too!) but these days it also uses a JIT interpreter similar to Dalvik to save from lengthy install/optimisation times. In recent times, Android itself has become far more power aware, and because it runs managed code on its Runtime Android can make power-efficiency decisions across all apps that iOS cannot (as easily). This has resulted in the bizarre situation that most developers thought they'd never see where Android devices now tend to have longer battery life (a few days) than iOS devices - which now last less than a day. The garbage collected memory of Android and its heavy multi-tasking still consumes a fair amount of memory, these days both iOS and Android are very well optimised for their general usage. The OS tend to use as much memory as it can to make the device run as smoothly as possible and as power-efficient as possible. Remember task managers on Android? They pretty much aren't needed any more as the OS does a fantastic job on its own. Task killing in general is probably worse for your phone now as it undoes a lot of the spin-up optimisation that is done on specific apps when they are sent to the background. iOS gained task killing for some unknown reason (probably iOS users demanding one be added because Android has one) - but both operating systems can do without this feature now. The feature is kept around because users would complain if these familiar features disappear. I expect in future OS versions the task-killers won't actually do anything and will become a placebo - or it will only reset the app's navigation stack, rather than kills the task entirely.",
"There are several reasons relating to the varying use cases as others have described, but the main reason is this: Android uses a form of automatic memory management that uses garbage collection, while iOS uses a more manual form of memory management. Garbage collection works better if there is always a good chunk of memory free, so the garbage collector doesn't have to run so often. URL_0 The reason to use garbage collection is because it saves the programmer from manually having to managed memory. Memory management is tricky, and if you make a mistake, you might begin to leak memory (memory consumption goes up slowly) or create a security hole. Recent versions of iOS use something called automated reference counting, which means that the compiler (technically the pre-processor) will figure the correct memory management automatically. This means that the workload of managing memory moves from the phone to the computer of the developer that compiles the software. The reason for this difference is historical. Android uses the Dalvik runtime, which borrows from Java, while iOS uses Objective-C and now Swift, which had a simple manual memory management system (manual reference counting). Apple used Objective-C because that is what they use in their own OS - Google used a Java analogue because it is a modern safe language that was widely by the time they launched Android, and so was easy for developers to learn.",
"I believe the true answer to this question is fascinating, and that it's actually just one piece in a bigger scenario (playing out **right now** that started in 1993) and that all of us are about to witness a transformation in the personal PC space that a lot of people wont see coming. First, lets focus on why the history of apple as a company put them in the position they're in today where they build everything in-house and it seems to work so well for them. Apple has the upper hand here when it comes to optimizing the software and hardware in a way that Google can never have, because Apple is calling all the shots when it comes to OS, CPU design, and device design. Google doesn't have that luxury. Google builds one piece of the handset (OS) and have to make it work in tandem with many other companies like Samsung, Qualcomm and Intel (for the radio). This is a very difficult task and is why OEMs like Samsung often have to also contribute a lot on the software side when building something like the S8. The reason Apple is in this position (where it can control the entire hardware/software creation of the device) is twofold. On the one hand Steve Jobs always wanted to control the software and hardware aspects of the Macintosh because he saw that it made it easier to provide users with better UX this way, and also the more control he could exert over the users the better. The other fascinating **and often overlooked but incredibly important** reason why Apple can do what they do with the iPhone has to do with IBM, PowerPCs and a little known company called P.A. Semi. You see, up until around 2006 Apple used PowerPC CPUs (by IBM) instead of x86 (by Intel). It is believed by most that Apple switched to Intel because Intel made more powerful chips that consumed less power. This isn't actually completely true. IBM is who made PowerPC design/chips and by the time 2006 rolled around IBM had sold off thinkpad, OS/2 had failed and they were almost fully out of the consumer space. IBM was completely focused on making large power hungry server class CPUs and here was Apple demanding small power efficient PowerPC CPUs. IBM had no incentive towards making such a CPU and it got so bad with Apple waiting on IBM that they ended up skipping an entire generation of PowerBooks (G5). Enter P.A. Semi. A \"startup for CPU design\" if there ever was one. This team seemingly came out of nowhere and created a series of chips called PWRficient. As IBM dragged its feet, this startup took the PowerPC specification and designed a beautifully fast, small and energy efficient PowerPC chip. In many cases it was far better than what Intel had going for them and it was wildly successful to the point where the US military still uses them in some places today. Anyway, their PowerPC processor was exactly what Apple was looking for, which came at a time when IBM had basically abandoned them, and Apple NEEDED this very bad. So what did Apple do? they **bought** P.A. Semi. They bought the company. So at this point if you're still reading my giant block of text you're probably wondering *but if Apple bought the company who could solve their PowerPC problem, why did they still switch to Intel?* And that's where the story goes from just interesting to fascinating: Apple immediately put the team they had just bought in charge of creating the CPUs for *the iphone*. See, people always ask *when is Apple going to abandon the Mac?* well the real answer is that they abandoned the Mac when they switched to Intel, because this was the exact time when they not only gave up but *abandoned a perfect solution* to the Mac's CPU problem, and where they instead re-purposed that solution to make sure that they **never have** a CPU problem with the iPhone. So what lessons did Apple learn here? That if a critical component to your device (i.e. CPU) is dependent on another company then it can throw your entire timeline off track and cost you millions in revenue lost (the powerbook g5 that never happened). Apple was smart enough to know that if this was a problem for the Mac it could also be a problem for the iPhone. When a solution arrived for the Mac they instead applied it to the iPhone instead, to make sure there was **never** a problem. And that team from P.A. Semi has designed Apples ARM CPUs for the iPhone ever since, and they're at least two generations ahead of the chips Android devices generally use, because they were first to market with a 64bit architecture, and first to allow the use of \"big\" and \"little\" cores simultaneously. And as for Mac users? Well, the switch to Intel allowed the Mac to keep living, but MacOS now comes second to iOS development, and new Mac hardware is quite rare. Apple has announced plans for app development that is cross compatible with iOS *and* MacOS. Apple has started shipping new Macs along with a *second* ARM CPU. The iPad Pro continues to gain MacOS like features such as the dock, file manager, multi-window/split support. All signs point to MacOS being on life support. When Steve Jobs introduced MacOS he said it was the OS we would all be using for the next 20 years, and guess what? Time's almost up. And the irony of it all is that history has now repeated: Apple now has the same problem they had with IBM, but now with Intel. Intel is now failing to produce chips that are small enough and that run cool enough. Apple will have to redesign the internals of the MacBook to support 8th gen chips due to changes intel made. Even the spectre/meltdown bug. The Mac is yet again dependent on a CPU manufacture in a way that harms Apple. So yes, the iPhone **is** something to marvel at in terms of its performance. You might be thinking Android is the big loser here, but really it's the Mac and it's Intel. I believe we at the cusp of an event that will make the IBM/PowerPC drama seem small. In five years from now we likely wont even recognize what MacOS and Windows are anymore, and Intel will either exit from the portable consumer space, or they will have to go through an entire micro-architectural re-design and rescue themselves as they did in '93 with the Pentium. In '93 Intel almost got destroyed because their CISC chips weren't as powerful as RISC chips such as PowerPC. Intel then released Pentium, which is essentially a RISC chip (think PowerPC or ARM) but with a heavy duty translation layer bolted on top to support CISC instructions that every Windows PC required. This rescued Intel up until *right now* but the industry has evolved and Intel's \"fix\" in '93 is now their biggest problem for two reasons: 1) they physically can't compete speed/heat/size with ARM now because they have to drag along this CISC translation layer that ARM doesn't need; and 2) Windows is about to introduce native ARM support with a **software translation layer**. Remember, Microsoft has the same CPU dependency problem that Apple has. And Microsoft's software solution allows them to throw away Intel for something better. Users wont notice the switch to ARM because it's transparent, but they will notice the 20 hours of battery life and thinner devices they get in the future once Intel is gone.",
"RAM on Smartphones is mostly used for multitasking, which means keeping more apps open at the same time. If a windows pc runs out of ram, it just takes the data of a process which isn't actively used right now and writes it to the Hard Drive, which means the process keeps running, but if you are trying to use it again you have to wait for a short ammount of time until it is responsible again. iOS and android dont do this, because it would cause a lot of wear on the integrated flash storage. Instead, when they run out of memory, they terminate a background app, so that if you open it again after that, it won't be where you left off, which is bad for the user experience. E.g. if you play some game on your smartphone, but you switch to whatsapp to write a message and check something on your browser, when the Smartphone runs out of RAM it will close the game, so if you switch back, you have to load it up again and maybe lose some progress. To avoid that, android phones just have a ton of RAM, but iPhones have a very sophisticated compression technique to store more inactive apps in the RAM. Candy Crush takes about 300-500 mbytes of RAM while active on both iOS and Android, but if you switch to another app iOS can compress it to about 40 mbyte, while on android the size does not really change at all.",
"I think most comments are missing the biggest thing and that's what the operating system does with apps in memory that aren't active. In short android keeps it in memory and it can execute tasks in the background (though it is moving to restrict background services), while iOS has only a few specific things that apps can do in the background and may use compression to reduce the ram usage. More info: URL_0 URL_1",
"Apple just has control over the entire software and hardware aspects of their phones. This allows them to standardize their code across a small set of devices. This standardization allows them to optimize their code to run on very specific hardware configurations. Android (google flavor specifically) only barely controls the software, and doesn’t control the hardware, given their open source strategy. Android has to work well on a myriad of hardware, and to some extent, a myriad of different software flavors. The carriers and vendors can make enhancements to the software. Because of this fragmentation of the hardware and software, it’s not cost effective to have to optimize 100% for every possible application of the software and hardware. Android’s promise is that it will run almost awesome all the time. It does this by throwing more resources from a hardware perspective (more ram, better processor, etc.) these hardware changes also allow the different vendors to differentiate themselves amongst each other, and allow them to prove their phones accordingly. This was all more evident in the early days of smartphones. Im am iOS guy myself, but even I’ll acknowledge android runs pretty solidly these days, and the issues are more subtle.",
"Has already been answered, but to simplify during the early days of Android they wanted it to run on a wide, wide range of hardware from ARM to x86 architectures. iOS was designed for ARM, and ARM alone. Therefore Android uses virtual machines to maintain compatibility across platforms, whilst iOS doesn't and they run natively. VMs need more memory than a native application. The very nature of JAVA is to run in a VM, so Java applications on PC and all other platforms are interpreted on the fly, C-based applications and other applications are not interpreted, and run \"natively\".",
"I'm not sure your question is correct. Even the latest Android os can run on as little as 512 Mb and only recommends 2gb (but obviously will take advantage of more if available). Therefore asking what iOS does to only need 1 or 2 doesnr make a lot of sense. They both do similar tasks and require the same amount of ram.",
"Could you people please stop with „Android is not optimized”? If you talk about some unknown brand, low-end phone, sure, it might be unoptimized, but don’t compare iPhones to cheap Android phones. [More high-end ones *are* optimized]( URL_0 ) Getting back to OPs question - [iOS is better in handling background app RAM management]( URL_1 ). If you use Android and switch between the apps, apps in the background free some RAM while they are not active and only if there’s no more RAM available, they get removed completely and need to be loaded up from scratch. iOS does the same thing, but better, making background apps use little RAM while still being able to load up fast when you come back to them. The downside of this approach is that when you use a split screen, both apps are active at the same time so they both use as much RAM as they need. Active RAM usage of the same app on iOS and Android is similar and sometimes even greater on iOS.",
"In addition to /u/xilefian mentioned about architectural differences, there is one other oft not known thing. There is a bunch of bad ass ninja engineers (~20 of them) that are Guardians of the Performance Galaxy at / iOS. Seriously, these men and women are bar none, the best engineers I've ever worked with and seen work. They can see the matrix, they can massage, cajole, coax -- and if needed -- judo your code to eek out that last few frames per second, prevent that UI/scolling hitch, and most importantly, be very efficient precious precious memory for your benefit. I've seen these performance ninjas re-write whole messaging subsystems, optimize memory management, and even work with the Silicon Wizards at Apple to add specific instructions that will help with compression, image de/encode, and various other sorcery. They hold office hours where I've gone with some colleagues and I'm floored at how they can open debug traces and ask you intimate questions about your architecture and code that they haven't even opened up Xcode yet, as if they divined the problem from looking at these trace files (which open up in a visual profiler, not Xcode) and told that performance problem \"you might as well come out unless you want me to drag you out by your ankles.\" All of this to say, the Apple Performance Team are a rare breed of Seal Team Six engineers which are a LARGE reason why iOS devices are so efficient with memory, not just that Apple the vertical SW and HW stack or their architecture. source: was a former engineer at ",
"While we could get really detailed talking about memory management here, it's more about what was more important to the set developers as there are benefits to both approaches. Simply putting it, most of this has to do with what each OS did with apps in the background. iOS puts the app into a kind of \"sleep\" function. Due to this it uses less memory, bit the trade-off is it can only perform certain tasks. Android, really just puts the app in the background running, meaning it can perform most tasks. Both will kill apps of they need to open memory for something else. Some of the decisions for this are based around that iOS is a much more closed off system while Android is an open system. What I mean by this is that iOS really comes with some things pre-installed that can't be deleted or replaced (keyboard, sms viewer, etc), while you can on Android. It really comes to different approaches the operating systems take and what they prioritize as important to the user experience.",
"Google is more focused on diversity than memory management. It's also evident in their other products like e.g. Chrome.",
"ELI5: Android was made to be universal, iPhone is heavily optimized and a unified architecture (opposite of universal)",
"Android is open source and has to work on hundreds of devices where iOS is closed sourced and only on what Apple wants it on. And because of that Apple can spend more r & d time optimizing it for each device. Also there is a difference is processor types and are different architectures.",
"They use different ways of programming. The android one is called Java which runs on many types of devices but is what is called an interpreter, which is a program which runs another program and in so doing runs slower and uses more memory. IOS runs a type of compiled C from the NeXT days called Objective C, which is compiled directly into machine code and does not involve an interpeter, so it is faster and takes less memory."
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7pyy5t | How is it that the tiny cameras in our phones can match the resolution of larger dedicated camera | Technology | explainlikeimfive | {
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"On paper it might match, but if you have ever compared the two the difference is quite noticeable. The sensor in a camera is very small compared to say a 35mm full frame format dslr. Therefore you can logically deduce that the resolution capturing of the light levels and detail as well as reduction of noise (inconsistent light transmission or refraction of light from particles due to light sensitivity levels or ISO of the sensor) will be better when the surface area of your sensor is larger. This is why if you were to look at a 1080 x 768 image produced by both camera types you can still notice a difference in color and pixel accuracy even in day time photos, let alone the more drastic different as light availability goes down. Also the quality of the picture not only reflects sensor size but also sensor quality, as well as the glass quality and type of lens focusing the light sources. It doesn't matter if you have the most expensive and largest sensor in the world, if you are using a piece of frosted glass as your lens you will get just a really large 2880 x 1440 picture of grainy blurs (albeit a very good one). Obviously great efforts are spent to make good quality glass that not only accurately focuses and directs the light onto the sensor in a way that doesn't introduce artifacts from glass production issues, distortion affecting extreme angles, or chromatic abberations from prisms and light angles, but is also light enough and practical for use on a camera. An example would be if you look up how they created the Hubble telescope which is essentially a single giant mirror that focuses all the light into giant sensors that use algorithms to filter out the noise and produce images. For what it's worth, the technology behind phone cameras has become advanced enough and will probably continue to do so to the point where the limiting factor may only be manufacturing tech or physics of light and mediums itself, but I'd say at a physical perspective it can only get so good as a dedicated camera. Besides phones are already so good at so many things that are enough for the average person anyways . In the end it's true the saying that the best camera is the one you have with you most of the time, because that's the one you will use and capture the moments with. A bad picture sometimes is better than no picture at all."
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7pz1qi | Why password managers are considered safe? | Technology | explainlikeimfive | {
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"Password reuse is a huge security issue. If it is compromised in 1 place, it is compromised everywhere. Without a password manager, many people resort to using the same password everywhere. If you have malware on your system, it is easier to compromise your browser, clipboard and log keyboard/mouse inputs than to compromise an encrypted password manager. A chain is only as strong as the weakest link. While a password manager may not be perfect, it is unlikely to be the weakest link.",
"The password managers are typically encrypted, which means that wothout the key (the password to access the file) the contents are giberish. They are also locally stored, which means that it is less exposed to potential hacks than a server that need to be up 24/7 for business purposes. It's tough (not quite impossible) to hack a computer that is turned off. To add to this, personal computers are generally not as worthwhile to breech for a criminal looking to steal personal or account information. The maliciously minded are better served by breaking into the corporate server that stores the information for thousands or millions of individuals. This is just a matter of necesaary effort vs potential reward. Therefore you need more things to happen before your password safe gets compromised than your bank login: 1) Your computer becomes infected with not just a virus, but a particular sort of virus that also bypasses your antivirus. 2) Whoever has access to your computer through said virus decides to look at yours in particular. 3) Before you realize your computer has been compromised and you change all your important passwords, the hacker breaks your password on the password safe file. These together make it highly unlikely that your password safe will be compromised, relative to many weak passwords on varrious accounts."
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7pzevl | How does a treadmill calculate burned calories? | On average, how does a treadmill at the gym calculate the amount of calories you've burned? Does it just guess based on your time and distance ran? Or does it actually take into account your weight? | Technology | explainlikeimfive | {
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"Depends on the treadmill. It could take into account your weight. If it's asking for your age, gender, height, and weight when you start a routine - absolutely. And if not, it could just make assumptions and give a rough estimate. That's all any calorie calculator is anyways - an estimate. The more biometric data there is the more accurate, but it's still an estimate.",
"The treadmill measures the force and speed at which you push back the conveyor belt, which allows it to calculate the mechanical work you're doing, in watts. Usually, the treadmill actually displays this number. Power is energy per second, so it can be converted into energy in joules per hour by multiplying it with 3600, and then dividing it by 4.2 to go from joules to calories. So 100 w of mechanical power translates to 100\\*3600/4.2 = 86 (kilo) calories per hour. That's the easy part. The difficult part is to figure out the amount of calories burned for the mechanical energy you produce. This is most likely a proprietary formula that varies with each manufacturer. The machines in my gym just seem to multiply it with 7 though, so the 100 w in my example translate to 600 calories per hour. Edit: Just in case you were wondering: What we call calories are actually kilo calories, which is why they are abbreviated \"kcal\"."
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7pzfmb | How do those anti-theft sensors at entry/exit doors at stores work? | I once went to the grocery store and did self checkout and I had multiples of canned olives and an employee came and said that I only had to scan one and then put in how many I have on the touchscreen. I said “wouldn’t not scanning them all trigger the sensor when I leave the store?” And they said “that’s not how it works” and then proceeded to tell me it’s a secret. So how do those sensors work? What exactly triggers it? Since I didn’t have to scan all the barcodes, does it factor in something else? | Technology | explainlikeimfive | {
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"The \"bagging area\" in a self-checkout machine is actually a scale. The approximate weight of an item is programmed into the machine. When you scan something, it \"expects\" that you will then put an item of that weight onto the scale and the total weight it is measuring will go up by that much. If you buy a bunch of something, it just expects that much more weight in the bagging area. This is why the machine bugs you to \"remove the unscanned items from the bagging area\" if you put something else near the bags (the weight went up without a corresponding item added to its tally) and also tells you to \"return the item to the bagging area\" if you take something out. The weight sensor could be fooled by items of equivalent weight, but that's one of the reasons that there's always at least one employee in the area watching over the people checking their own items out. Most supermarkets do not have any actual sensors by the door, as with their generally higher sale volume it would impractical to put a radio transponder tag on every item like they do at clothing or electronics stores."
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7q0u8d | why do unused batteries slowly die out over time without being consumed? | Technology | explainlikeimfive | {
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"batteries make electricity by a chemical reaction between two reagents in a closed container. over time those reagents and the container degrade and are not longer able to make the reaction happen."
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7q0x2w | How do so many mobile games rip-offs of games like Candy Crush, Clash of Clans, Slot machines, (ect.) make money and get players in such an over-saturated market? | Technology | explainlikeimfive | {
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"because even 0.01% of an oversaturated mobile app market of 50billion is still a butt load of money. and that's incentive enough for a company to try to get a slice of the pie."
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7q18b3 | Is a Solid State Drive (SSD) basically a Hard Drive made out of RAM? | And the one I got says it's "V-NAND" (Vertical NAND). I understand what a NAND gate is, so how does that translate to "V-NAND"? | Technology | explainlikeimfive | {
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"SSD's are made out of Flash memory, which is a form of RAM that is non-volative (e.g. it doesn't lose data when power is removed). It's the same type of memory in a USB stick. Flash memory can be made from both NAND & NOR gates, with different performance characteristics. NOR flash allow random access to the byte level & high read speeds, at the cost of density. NAND flash has to be accessed by blocks by has higher density. Most storage devices, including SSD's, are made from NAND flash as the performance benefits of NOR aren't worth the density trade off. NOR flash is used in niche areas when appropriate (for example, instruction memory in embedded devices). For the Vertical I'm not 100% sure what the technology is, but it's likely a production technique that either stacks Flash cells, or uses a different orientation (like FinFET) to increase density.",
"Sort of, except it doesn't use normal RAM chips, it uses another variant of memory chip called Flash Memory. Advantage: unlike RAM it doesn't lose its contents when the power goes off."
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7q544m | How are those glass decorational items made? The ones that are just a solid glass blocl, but with some kind of 3-D image inside of it? | They kind of look like they're hollowed out but show no signs of being seamed together. | Technology | explainlikeimfive | {
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"Lasers! You take a few lasers pointed in from different angles and have them cross at a single point. Individually they don't have enough power to damage the material but they do when you cross multiple beams",
"They're called [sub-surface laser engravings]( URL_0 ) or bubblegrams. When doing laser engraving, typically they focus the laser on the surface of the material. It creates a microscopic fracture. With glass, crystal, and certain plastics, you can focus the laser below the surface. This causes the microfracture to occur deep within the glass itself, not just at the surface. By adjusting the focus depth, as well as the X and Y coordinates of the laser, a 3D engraving can be made."
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7q9s23 | how can they continue to discover more chambers in the pyramids year after year | Technology | explainlikeimfive | {
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"Several reasons: * Better technology. Many chambers were detected by sonar or radar. They would send a signal through the stones and listen for irregular echoes. Today's sonar and radar imaging techniques are better than they were in the past. The equipment is more sensitive, uses different frequencies, and with digital signal processing, they can construct a better, 3D map. Robots can crawl through tinier spaces than ever before. * Different technology. IR and UV cameras that weren't available to the public several years ago are now consumer off-the-shelf technology. Drones can carry cameras to vantage points that were inaccessible before. * Different permissions. You have to get permission from the Government of Egypt to do scientific studies of the pyramids. Over time, the types and locations of research have changed.",
"Many of the rooms can't be reached and the researches can't use any destructive techniques to get to them Several of the rooms were blocked by large stones when the pyramid was sealed up, explicitly to keep people out of the tombs. Remember, the Egyptians built the Pyramids to safely hold the bodies of the Pharaohs undisturbed forever. They were made so they would be very difficult to access once completed. We have to use creative techniques to find rooms that are sealed behind dozens of feet of limestone",
"We don't want to damage the pyramids, so we have to use clever methods of seeing 'through walls' to discover rooms which are blocked behind collapsed stone or sealed away. As our technology for 'seeing through walls' gets better, we can explore more of the pyramid interiors without fear that we will harm them. Also, the kind of radar and geophysics used to discover underground buildings and chambers has the benefit of being surrounded by dirt or sand, and since dirt and sand are very different to stone, it's easy to find.",
"They are sealed behind walls that we can't just tear down in most cases. There's also just a ton of stuff to study there and who gets to work where is pretty tightly controlled."
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7qflvx | () How can a lens have a focal point of infinity? | You often hear of photographers and videographers setting their cameras focal point to infinity. How does this work? Won't the lens still focus at a specific distance no matter how far away it is | Technology | explainlikeimfive | {
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"When you're looking at infinity, light waves are basically parallel. When you're looking far enough, it's little different from infinity."
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7qiwmm | how does fast charge/ quick charge work ? | i wonder what those special dedicated charger do , do they have something special inside phone as well which make them accept more power , or just its just capabilities of charger ... and how can phone recongnize if the charger connected is say from same company , eg can huawei phones use fast charger from phones with qualcom ..? | Technology | explainlikeimfive | {
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"USB has a standardized voltage, quick charge at it's simplest is just using USB power delivery outside of the standard (more voltage). To not damage anything, the charger and your phone communicate to determine if they are quick charge compatible with each other, if not they revert to USB standard which is guaranteed to work."
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7qj73x | What is the purpose of having many cryptocurrencies? Who benefits and why? | Technology | explainlikeimfive | {
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"Mostly the vast majority of coins right now are gaining value on hype, marketing, and illusions of lambos. They will fall away and dissolve. We call them shitcoins. However there are many coins attacking real problems. IOTA is bridging the eventual future of machine 2 machine economy. Creating a coin that can transfer value and data amongst connected machines is crazy. XRP and XLM are vast improvements on the archaic Swift and even CC transactions. Why do I pay dollars and wait 3-5 business days for an international transaction when ripple can do that in seconds for a fraction of a penny? DAG coins can do instant and feeless transactions around the world. ETH is a platform which decentralized apps can be created and smart contracts executed, my dollar bill can’t do that. BEE token is an upcoming launch that puts house sharing (on the blockchain and eliminates fees charged by the hosting website (like Airbnb and vrbo do) Coins like Monero and Sumo are privacy coins that allow people to transfer value without having to disseminate who they are, how much they are transferring , and to whom. Why does the govts need to know everything we do monetarily? These are just some of the coins that have been created with great opportunity for real world value and improvement (in my uneducated opinion of course).",
"(Disclaimer: I am very critical about the whole cryptocurrency hype, but i did lots of research into the topic and i am doing IT research in my daily life, so i am probably more knowledgeable about the underlying technology then most people, even though that knowledge doesn't help at all when it comes to cryptocurrency.) At the moment most cryptocurrencies are mostly valued based on popularity. Some old and experienced investors and speculators compare the value of bitcoins to the value of Facebook and other social networks. If they have more users they have more value. Another indication of this is, that the price of a coin seems to rise with the amount of google searches in a certain time. But how this interest starts and develops over the next few days (or even hours) is really hard to say. If you can do that you could probably make a fortune at the moment and i am sure that some people abuse this effect and make lots of money by generating interest in a cryptocurrency to sell them afterwards. It actually reminds me of the not so distant past when spam emails advertised certain small stocks to raise their value just to sell them when they are at the top (Just google \"stock market spam\" and you will find tons of information about it, i think it's kinda interesting and relevant at the moment just to make sure you're not on the losing side of something like that). I think there will be a point in the future when the underlying technology and the actual use case of the block chain and cryptocurrencies become more important, at which point they'll become more interesting to me. But at the moment i'd say 99% of the cryptocurrencies will rise fast just to disappear again and 99% of the people investing into ICOs don't have a clue about the underlying technology. They just blindly believe that this will be the technology of the future, even though it might just do something we already have in an unnecessary complicated way. Unlike many people say it usually isn't necessary to have a decentralized system, usually centralized and regulated is a lot easier to build, use and manage. Another problem with many of the companies is the lack of valuation, it's very similar to stocks some are overpriced some are undervalued, but in my opinion the whole \"bitcoin it's the future\" hype makes overpriced a lot more likely in many cases. Reminds me of the dotcom bubble, it sounds new and interesting and people don't really understand it. If you ask me that is a scary mixture, but it could make you a lot of money."
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7qjrng | How does non-scratch glass work? | Technology | explainlikeimfive | {
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"Alot of your non scratch glass undergoes a special treatment in which smaller sodium ions are replaced by bigger potassium ions. This an ion exchange reaction at very high temperatures. When you think of a lattice, the positive ions (cations) are the smaller atoms in the lattice and they sit in the gaps of the lattice. Because the ion exchange reaction placed bigger potassium ions in those gaps the lattice is more dense and under alot more compressive stress. The result is a harden surface. If you try to scratch this harden surface the increase compression will 'fight back'. Basically the bigger potassium atoms push the surface together so hard that a knife cant break through.",
"The latest versions aren't normal glass, they're artificial sapphire, which is very, very hard. You can scratch it with diamond but your keys have no chance.",
"usually by not being glass. the most common way is to put on a chemical coating that's much harder than glass. the particulars vary with brand, there are all sorts of minerals that do the job."
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7ql29n | Why is cold air better for an internal combustion engine? | Just wondering why a cold air intake increases performance on a car engine. | Technology | explainlikeimfive | {
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"Cold air is more dense, meaning you’ll get more air. So, a cold air intake increases performance by giving a lot more air to the system.",
"A colder air/fuel mixture will also be more knock resistant, which means that a more advanced spark timing can be used. More ignition advance means more power, if the engine is knock limited.",
"A \"cold air intake\" is often a hot air intake that ironically removes the factory cold air intake most of the time. People love them cause they make the car louder, even though they sometimes make the car slower than stock. You will notice your car is \"faster\" on the butt dyno, but that's because you took a smooth and linier power curve and made it peaky. Save your money for basic maintenance and factory replacement parts.",
"As a side note to all the previous answers, there's even a theoretical engine maximum efficiency whose value is function of the outside temperature and of your engine operating temperature. Maximum theoretical efficiency (assuming friction free engine with no entropy loss) is equal to 1 - T(air)/T(engine) where the temperatures are expressed in absolute unit (such as Kelvins). Basically, the colder the outside air, the more work can be put into it (generally via compressing it even further in the piston cylinder) to bring it to the engine's operating temperature."
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7qmpbh | How do deep learning engines/algorithms work? | Technology | explainlikeimfive | {
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"Basically you provide a way to tell the deep learning network, if it's doing a good or bad job. For instance you hand label lots og images and see if the network gives the same label. Then when the network does a bad job, you can calculate how the parameters in the network should be tuned to avoid the same mistake. This is extremely simplified, feel free to ask if you want more info."
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7qn9bs | Why is it better for Lithium-ion batteries to be charged after a partial discharge and not a full discharge, unlike the Nickel-based batteries? | Technology | explainlikeimfive | {
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"It's essentially just due to different chemistries and material interactions. Lithium-based batteries generally suffer damage from deep discharge, so it's not recommended to let them get to low. Nickel-based batteries are kind of the opposite, such that doing a full discharge and recharge serves to heal the battery a little. The specific reasons behind why the lithium-based batteries are damaged varies between their various chemistries (there are dozens of main mixes, and that's even before you get to lithium-titanate batteries).",
"Nicad batteries (which have not been in common use for quite some time) suffered a \"memory effect\". To keep it simple, repeated partial discharging could result in an apparent loss of capacity below the partial discharge point. A more complete discharge and subsequent full recharge could prevent the appearance of this scenario. The issue was largely exclusive to nicad batteries. Lithium cells and NIMH batteries do not suffer from this problem. As such, deep discharges do not bring any benefit to those batteries, and can do more harm than good to the overall life of the battery."
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7qni8s | how are the cvv code and expiration date of the credit card enough security measures in eshopping? Why don’t we have to insert the pin and the stuff that is written on the card suffices? | Technology | explainlikeimfive | {
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"The whole premise of credit card operation is that you give the merchant all of the information they need to tell the credit card company to give them some money (which the credit card company later makes you pay). Any merchant--not just online--could keep a copy of that information and charge you later. The magnetic swipe just stores data, in the same sense that the numbers on the front and back are just data. This is secure enough because when fraud is detected the credit card company goes to wherever the number was used and takes the money back. This screws over merchants who inadvertently accepted a stolen credit card, but merchants can't just not take credit cards or else they'll lose out on a ton of business. It's also secure enough because if a card is compromised it's cheap to just issue a new one. The card itself is pretty darn cheap. With that said, \"secure enough\" is a sliding scale, and it has to be weighed against convenience. The Chip+Pin or Chip+Signature systems are more secure, but there's no good way to use these online."
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7qo7sj | how do people put oxygen in a oxygen tank? | Technology | explainlikeimfive | {
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"> how do people put oxygen in a oxygen tank? The first step is to isolate the oxygen. In an industrial scale this is usually done by compressing air, allowing it to cool, then letting it expand in order to cool even more. Different gasses precipitate out at different temperatures which means they can be distilled into nearly pure forms. At that point liquid oxygen can be shipped around and oxygen tanks filled from pressurized containers."
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7qovsz | Why can't a barcode/qr code store an executable virus? | Barcodes and qr codes are capable of storing a good amount of information, so why can't they store a virus? | Technology | explainlikeimfive | {
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"Barcodes, whether one or two dimensional, are rarely used for more than a few hundred bytes. It would be difficult to place malicious code in such a space, and that code would have to exploit a weakness in a particular scanning application, which could be patched relatively quickly.",
"In theory, a QR Code could. Barcodes probably not since they hold so little data, often only a single number of fixed size. But QRs can be quite large. The problem would be to trick the scanning device (or some other part of the system) into executing that code. One would likely need to exploit some vulnerability along the way. For example if the data from the QR code is displayed on a web page, an attacker could embed malicious JavaScript code in it and if the website doesn’t sanitize it’s output properly, that code could be executed the the browser that visits the website.",
"Viruses require an exploit to actually do their thing, just the payload existing isn't enough. There has to be some flaw in some software that can be manipulated to make it happen. In the case of barcode scanners, typically those are pretending to be a keyboard for the host computer and the host machine reads it as if someone had just typed thos numbers into whatever box. Unless whatever that box is is flawed, this is a no go. QR codes usually instruct your device to go to a web address and retrieve some resource, usually (though not necessarily) a page. You could deploy malware here if you know of some browser exploit you can stick in a URL (like naughty javascript) but other than that, no go either.",
"I’m not sure about QR codes, but a barcode is literally just a sequence of numbers that the POS system uses to consult a database to get the price of the item.",
"> Barcodes and qr codes are capable of storing a good amount of information Not really. The largest standard QR code is 177x177, and is capable of storing about 3000 bytes at the lowest level of error correction. While I won't say it is impossible to make a virus that size, most are well over 100,000 bytes.",
"Barcodes and QR codes don't really have enough room for a proper virus and even if they did, most readers aren't set up to try to execute the data they read. You can of course try to format a qr code that you know will be read into a database in without sanitizing inputs in order to screw with the database, but that is not really a virus atack. Another thing that somebody actually did was to create a QR code that was a link to a website knowing that some smart-glasses were configured in such a way that they automatically opened such links without user intervention and then have malware on that webpage that tried to attacked though known vulnerabilities in the browser. That is quite a nasty concept an image that can infect your smart glasses just by looking at them (like a real world Basilisk image), but that is little more than a signboard that says go to that website that has viruses rather than a virus directly on the signboard. Still if you have enough space (QR codes max out at 3kb) and know how the reader will process the data it reads and the people who built the system that processes the data were complete morons you can potentially use it to infect a system."
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7qpt6n | What does 'tension' in High Tension and Low Tension cables mean? | Technology | explainlikeimfive | {
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"Have you ever seen those videos where they create a tree pattern in a slab of wood using electricity? That's what high voltage wants to do to everything it touches, so if you are going to insulate a cable for, say, underground transmission you have to use an appropriate insulation. \"Cross-linked polyethlyne\", or XLPE, is common but there's a lot more to it you can read about. The tension in high and low tension cables simply means the level of voltage it (the insulation) can withstand under normal conditions. I highly recommend you watch some videos on cable joining to see how important the insulation and proper care/installation is on high voltage cable. It can be a tedious and lengthy process and everything has to be done cleanly and without scratching any cable or letting any moisture in. Even more interesting is the use of \"stress relief\" tape or cones specifically to mitigate the tension at a high voltage join. I tried finding a product video I was shown at my old job that showed the difference vs not using one. Fascinating stuff."
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7qx4sc | - What happens when I'm redirected to a site that says my computer is infected? | Technology | explainlikeimfive | {
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"If the *site* says your computer is infected, it's a lie. They are trying to sell you a service for money. If your antivirus program says the site is infected, it's likely true, and it just protected you, and you should avoid going to that site.",
"it's an attempt to install malware onto your system. clicking yes will install malware. clicking no will install malware. clicking the close window link will install malware. what you do is Ctrl F4 or go to the start menu and bring up task manger and kill the browser. now you know how easy it is to get infected"
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7qxcrt | Why do LED lights look jittery or like they're strobing when you look at them quickly? | Technology | explainlikeimfive | {
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"They look like they are strobing because (for most of them) on mains power they actually are! Much like when whatching TV, however, something called ”persistence of vision” smooths it all out for you. When blinking or looking away quickly your brain \"preserves\" what you saw in that instant and you can spot it. You can also see it when something is moving quickly across your vision. Similar stuff happens when you dim LEDs (like LED car taillights when the brakes aren't on), though much, much faster through something called PWM. The LEDs are switched on and off really quickly - when they are on for half the time they look half as bright. In theory PWM is too fast to be perceivable (when done right) but it seems a lot of people are actually sensitive to it! You can also get strobing from HID headlights because they often use AC to get the thousands of volts they need to ignite. *This bit goes a little beyond ELI5 but hopefully still helps. My inbox kinda exploded and I've tried to answer repeated questions in the edits.* Strobing is (historically) very common with LEDs driven from mains AC. You can often see the effect if you wave your hand back and forth while focusing on a stationary spot - instead of smooth motion blur you can see a series of hand images, like stills from a movie. Cheap camera phones also sometimes show it. So why does this happen with LEDs but not other lights? In your mains AC, the voltage alternates from positive to negative and back again 50 or 60 times per second. That means that 100 or 120 times a second the voltage is exactly **zero.** Zero voltage, zero power. In traditional incandescent lights there is a fillament which is heated super hot to provide light. This fillament takes time to cool down - much longer than the mains supply takes to go through zero - and so it can stay hot, keep putting out light, and there is (almost) no flicker. In LEDs, there is no fillament to heat and they react *very* quickly. When the voltage to them starts to drop towards zero, the lights dim and turn off, coming back on again as it voltage goes back up. As this is happening at 100 or 120 Hz, most people wont notice it. Cheap or traditional triac based dimming can seriously exacerbate the issue with mains strobing. In higher quality power supplies for LEDs, they use \"smoothing capacitors\" and/or purpose designed LED drivers to help the LED stay lit through the low/zero volt bits and this reduces the strobing effect. Incidentally, flourescents also strobe (though to a lesser degree) and most video cameras have special software to help hide this. Obviously with battery (DC) powered stuff, excluding dimming, there is no AC and so no strobing. **E:** typos **Late E2+:** Some battery powered things can use DC to DC transformers which can in turn cause strobing, so the above has caveats. LED car headlights may fall into this category. I have assumed above that we are talking about incandescent replacement globes which almost always have a full bridge rectifier. For single diode lights (Christmas lights, dim indicators, or other decorative lighting) it is half the frequency and more noticeable. The flicker many people mention in slow motion footage of car LED taillights is almost certainly PWM dimming for combo brakes/running lights. Brakes on, full power, running lights, dimmed. **Regarding strobing headlights**, chances are they are HID lights not LED. HIDs need thousands of volts and have transformers (called ballasts) to get this, in turn meaning almost certainly an AC voltage being produced. Much like flourescent tubes, or arc lamps, there is no fillament to help it ride the zero crossing in the AC signal and they strobe. If it is absolutely LED then I would suspect it has to do with being a fancy matrix LED configuration which automatically controls the beam pattern (PWM?). Might also be DC to DC transformers at play. I also found it really interesting how many people have issues with PWM lights. Common wisdom used to be anything above 1 kHz was impossible to see with the naked eye... the exact frequency used in PWM is kinda arbitrary though, apart from lower is easier. Nothing stopping someone using PWM at say 200 Hz instead, which might be where the issue lies. If strobing bothers you the good news seems to be that a lot of newer high quality LED globes have switch-mode and/or smoothing built in, however it's not clear how to tell from the box. I did a search on Amazon and I couldn't find the right magic words. YMMV. If you have the chance to use them in person, at least one variety will stay on for a fraction of a second after you turn them off, so you might be able to look for this. Dimmable sorts might also be better.",
"They're often dimmed using PWM(pulse-width modulation) in cheap applications. Basically they're turned on and off really quickly and by changing the ratio of on time to off time you can change how bright it appears to your eyes. The problem with this is that when they move through your vision(you turn your head or they move) or you wave something in front of them you'll get weird results because its not on all the time. There is a distinct image that only appears at specific locations on your retina instead of being a blurry smear across it like your brain expects from a continuous source. Good applications will instead provide constant power and control how much current is flowing through the LED. Providing constant power means they aren't turning on and off and don't leave you with the weird jittering effect.",
"If you’re referring to Christmas lights, they’re usually directly driven from the AC power in the wall through a diode (like a check valve for electricity, one way flow) and a resistor (to drop the voltage to something the string of LEDs can handle). AC current flows back and forth, but LEDs can only operate in one direction. The diode allows the flow one way, so the LED’s only work half of the time. In the us, AC power changes direction of flow 60 times per second (60Hz, funnily because it’s a pleasing tone to hear hum, and for that reason alone). The LEDs can only use half of those cycles, so they flash 30 times per second. When you’re looking at this flashing LED string, it appears like they’re solid ON, but dart your eyes and they’ll flash! Your persistence of vision is what fills in the gaps, because it takes a second for your eyes to refresh their electrochemical reactions. Try recording these LEDs on a slow motion camera, like some phones have. You’ll see the flashing. Even without a slow motion feature, most phone cameras will mix in and out of sync with the LEDs flashing, so they could fade from on to off slowly.",
"It must be noted that this is not always true. Having played with the Saturn model of the 2000s toy astrojax, I can attest that it is entirely possible to have LEDs that don't appear to strobe when you shift your vision that quickly.",
"Try looking at LEDs while using an electric toothbrush... Or like, hold a vibrator against your cheek.",
"The short answer is that it is a relationship between the frequency at which the driver operates and the visible flicker that the human eye can see from an LED light source. LEDs are DC components by nature. Apply a DC voltage and current, and voila! Light. Commercializing such a device requires extra components, specifically an LED driver, which takes the AC that your home provides and coverts it to DC that can then power a series of LEDs. These drivers have an operational frequency, the rate at which they cycle the power to the LED. In modern LED lamps, these frequencies are well north of 2000 Hz. However, a driver that is compact enough to fit in a retrofit lamp comes at a cost. So some manufacturers will still use drivers that operate at 100 Hz to save money/cut corners. That's all well and good, however research in the past 20-some years has shown that the human eye can detect LED flicker at an average of 100 - 120 Hz in LED sources. Why is this not a problem with the old tungsten lamps, you ask? Well, LEDs turn on and off instantly in response to the power supplied to them, on the order of microseconds, while tungsten lamps operate by heating a filament to a peak temperature. 50 or 60 Hz is not perceivable by the human eye when the rate of change is so slow, in this case hundredths of seconds. Filament heats up, cools down, rinse, repeat, but that change is slower than the power cycle of your house. In general, most modern LED lamps/retrofits don't have this issue anymore as the cost of components has dropped precipitously to the point where practically anyone can compete in the open market with LED products. Dimming, specifically PWM dimming of LED lamps using residential wave form chopping dimmers, is an entirely different matter. Mostly because cross-manufacturer standards are slow to solidify. Source: M.S. from the Lighting Research Center at Rensselaer Polytechnic Institute, and years of developing LED lighting fixtures for commercial applications.",
"Gonna jump off this because it's slightly related. Does anyone else get an odd feeling like they lack depth perception when looking at those blue Christmas LEDs?",
"Ooo something I can actually help with. I'm currently working for a company investigation the health risks to this strobing and trying to develop better LED lighting for the world! But seriously, most LED lights are flickering, especially ones that dim. It's all due to the conversion from AC electricity to the DC required for the light. This conversion is never perfect and the companies who make the drivers in the LED lamps are more concerned with making them ever so cheap that they couldn't care less. There's some papers I can dig up by a lighting group who've been looking into, not only normal flickering, but also the 'stroboscopic' effect you see when either you or and object you're looking at is moving quickly under one of these lights. There's some really cool article online about some sports arenas not checking for this and having some real trouble.",
"They are. I took a slow mo video of my Christmas tree that has white LEDs and it looks like they're flashing.",
"Would LED bulbs be something that a person with epilepsy would want to avoid? Or is it too high a frequency to trigger seizures?",
"I'm surprised no one has mentioned multiplexing yet, which is the other reason they can appear to flicker. To save on wiring and output pins, it's often the case that the the voltage for each segment of a digit is applied to all the digits at once, and then only the intended digit has that current sunk. So 12:34 would go: **1**1**:**11 2**2:**22 33**:3**3 44:4**4** Where the bold digit is the only one that's lit. It happens quickly so you don't notice it usually, but your peripheral vision is more sensitive to it.",
"Pull out your iphone and record the lights with the slow motion camera. Watch the video and be amazed",
"You already got your answer. I'm just piggybacking so I can rant about PWM LED tail lights. I hate 'em. And they've probably caused accidents, because since the eyes perceive duplicate tail lights rather than just a single blurred one, that certainly can't help in a split-second traffic incident.",
"So I've noticed this as well. [Here's]( URL_0 ) a long-exposure shot of our LED-lit Christmas Tree while I zoomed in for an effect. If you look closely, you'll see each bulb on the tree was blinking, but to the naked eye they are always lit. This picture was a .3 second exposure.",
"The first step is to understand what a LED is. It's a Light Emitting Diode. A diode is an electrical device that only allows current to flow in one direction. The reason this is important is because the power out of your walls is typically AC power, or alternating current. The alternating current refers to the fact that the current flips from positive to negative very quickly. Because I diode prevents current from flowing in one direction this means that the diode actually turns off for a split second, every time the current goes negative, causing the flickering."
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7qzcrv | How do voice actors match their voices perfectly to the mouths of the characters in animation movies? Do animators animate the mouth movements after the voice actors finish recording their parts? | Technology | explainlikeimfive | {
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"For western animation, audio tends to be recorded first, for anime, the audio is usually recorded after the animation is complete due to differing production schedules. Note that this is no more than a rule of thumb, it does not apply to any and all cases. Akira is a notable example where the audio was recorded first. Of course, this changes with non-traditional animation. When working with 3D CGI it's generally easier to animate everything but the mouth movements then can fine tune them as needed (or even mo-cap the facial expressions) for the final product."
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7qzsy0 | Why are PC hardware prices rising so fast? | Technology | explainlikeimfive | {
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"If you look around /r/buildapc, you'll be able to keep up on some of this stuff. Nothing really exciting is going on with *most* PC hardware but two major things stand out: First off, the *absolutely fucking insanity* in the cryptocurency (Bitcoin, etc) has created a lot of demand for mid/high-end video cards. When this demand outstrips the supply, it pushes the prices of video cards up. Secondly, RAM prices are also seeing a rise in price over what we saw a year ago. A year ago, prices were low because there was too much supply, now the supply has dried up as manufacturers cut back production of low-margin products, pushing prices higher. CPUs, storage & motherboards are still behaving pretty typically. We're at the start of a new generation of CPUs & motherboard chipsets so those are going to be a bit more expensive than what they're replacing but it's a pretty standard thing."
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7r0p36 | How do they manage to carry out cards payments on airplanes? | Technology | explainlikeimfive | {
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"I assume you mean credit card transactions such as purchasing alcohol on airplanes? Most planes today have wi-fi and internet connectivity, even if it is not available to the passengers. The portable credit card terminal can communicate with the payment processor over the plane's internet connection just like it does in the store."
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7r1o0i | How do server farms work? | How do all of these computers communicate with each other and organize everything? | Technology | explainlikeimfive | {
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"Usually there is one or more boss computers who hand off tasks to the worker computers. Sometimes there is a big boss computer handing off types of jobs to little boss computers who then decide which worker computer will do each job.",
"a server farm is basically a big building with lots of server computers inside. the computers don't necessarily speak with each other. they can be doing different things for different clients for different purposes. current implementations of \"cloud\" mean that a single physical computer might be serving different virtual computers inside. virtual computers that run different operating systems, different applications, paid for by different customers. not all the computers (physical or virtual) in a server farm will talk to other computers in the farm. there might be customers that only talk to their single virtual computer. there might be customers that want 10 virtual computers but don't care if it's on the same physical server or even in the same building. computers talk to each other the same way your computer talks with your router. all electronic signals thru network cables."
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7r7ptj | zipped files | Occasionally when I download content online, some files require me to use winrar to unzip them. What exactly are zipped files and how does unzipping them work? Also whats the purpose behind zipping files? | Technology | explainlikeimfive | {
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"Zipping files makes them smaller without losing information- how exactly it does this, and so what needs to be done to get the original file back, depends on the algorithm used, but the basic principles are consistent. When a file is zipped, what happens is that it's analysed for commonly repeating elements. These are then replaced with a shorter 'code', which is stored in a 'dictionary' that gets stored as part of the zip file. In order to do this, rarer elements have to be replaced by longer alternatives, but the net effect is to store the information more efficiently if there are a lot of common patterns- as occurs with text (lots of 'e's and 't's in English, for instance) or programs (control characters tend to get repeated over and over again). When you unzip the file, the file is 'read' using the dictionary to get the original back- allowing it to be used!",
"Zip is a format for compressing files. Compression uses an algorithm to find patterns in the data that makes up the file, and then stores those patterns instead of the whole file. This saves space on your hard drive, and bandwidth when downloading, though it takes some processing power to decompress (un-Zip) the file when you want to access its contents. There are other formats for compression, with extensions like .rar, .gz or .7z."
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7r7w4p | Why do lines appear in the picture when you photograph a computer screen? | Technology | explainlikeimfive | {
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"[Relevent XKCD.]( URL_0 ) Your computer's made of a bunch of little squares that all work together to show you a single image, called pixels. These pixels are arranged in a grid of rows and columns to display images on our screens. Now, your phone or camera also has a pixel grid, but unless you have a really specific device, chances are it's gonna have a different size pixel grid than your computer. Since these grids are different sizes, they don't play nice with each other, and that's why the computer grid is visible in photos, because the camera's grid won't sit neatly on top of the computer grid, \"hiding\" it from view.",
"Screens do not generate an entire image at once. Rather, each row of pixels is rendered one at a time until the entire image is rendered. Imagine the screen as filling in a color by numbers from left to right one line at a time. This happens a number of times per second based on your framerate. A 59.99 hertz screen does this nearly 60 times per second. If your screen has 4000 pixels, it does one pixel every .015 seconds. Similarly, most digital cameras use what's known as a rolling shutter. They don't capture the whole image at once, but instead one line at a time. This is similar to how a photocopier works. When the rolling shutter is out of time with the framerate of a screen, it catches different cycles of rendering in the same still. Imagine if you could instantly swap out a series of photos while a photocopier tried to scan them. You'd end up with a similar effect."
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7r87bn | What is an RSS Feed? | What is an RSS Feed? I always heard about it but never bothered to look it up. I just want a simple explaination of what it is and what its used for | Technology | explainlikeimfive | {
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"A good example might be a news website. The user subscribes to the websites RSS feed using RSS reader software, then whenever the news website publishes a story, it is sent directly to the user without them needing to check the website. If you've ever subscribed to a podcast it's pretty much the same idea. The podcast is sent to you rather than needing to check its website and listening there."
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7r9hcp | What is ILS in terms of flying? I've heard numerous pilots use the term. | Technology | explainlikeimfive | {
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"text": [
"Instrument Landing System (ILS) is defined as a precision runway approach aid based on two radio beams which together provide pilots with both vertical and horizontal guidance during an approach to land."
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7r9vh7 | How do swipe card and their readers work? | Technology | explainlikeimfive | {
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"There is a strip of magnetic tape on the back of the card. There is a magnetically sensitive reader head in the swipe machine. As you slide the card through the machine the tape on the card creates a tiny electrical signal due to the interaction of the magnetized tape and the reader head that changes as the card slides through. These small changes represent the data stored on the card which includes the card number and I believe also the expiration date."
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7rax52 | Why are trains operated by humans, when we have driverless cars, which seems like much more diverse and complicated tech. | Technology | explainlikeimfive | {
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"there are plenty of driverless trains. IIRC, german and french subways are driverless. the problem isn't the technology. it's the budgets of the metro gov and politics of the train driver unions. technology costs money and reduces government jobs. that's not a popular sentiment for government.",
"Driverless trains are simpler but much more expensive to implement, as they require specialized equipment to be installed all along the track. Driverless cars are much more complex, but all the equipment that makes them self-driving is in the car itself. This means they can be used on existing, un-modified roads."
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7rdssy | Why Do Old CRT TVs Make A High Pitched Hissing Noise? | Technology | explainlikeimfive | {
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"The noise was usually attributed to the fly back transformer that was used to generate high voltages for the crt tube. Transformers generate an alternating magnetic flux that would separate the laminations in to core and cause them to vibrate with the alternating current."
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7rdupb | if you can't film CRT TVs properly because the screen refresh rate is out of synch with the camera's shutter speed, how to filmmakers create shots with CRT TVs playing normally? | Technology | explainlikeimfive | {
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"> if you can't film CRT TVs properly because the screen refresh rate is out of synch with the camera's shutter speed, how to filmmakers create shots with CRT TVs playing normally? There are two good ways: You could synchronize the shutter speed with the refresh rate of the CRT, or you could have it show a blue or green screen and edit in whatever you wanted after filming. The former was probably easier early on, and the latter probably became more popular considering the flexibility it offers.",
"There are modified TV systems (cameras, graphics, monitors) which run on 24 Hz. I know a guy who moved to Hollywood just to build and rent out those systems."
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7rduum | How does Nintendo's labo work? | I just don't get it? Is it just cardboard and you have to pretend that your doing something or is there more too it? | Technology | explainlikeimfive | {
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"In conjunction with the software, the IR sensors in the right joy con allows pieces of reflective plastic inside the cardboard to sense different movements and then the software reacts accordingly.",
"The piano works by pointing the right joycon into the body of the box and pushing a key changes what the IR camera views (I'm guessing it lifts small paddles on the inside via lever motion). The camera can detect basic shapes easily and determine distance of objects so that must play into how it works too. The software the kit comes with interprets what the camera sees and outputs the corresponding notes. The robot vr backpack looks like it uses the gyrometers (things that can sense motion) of the left joycon headset piece to determine view while it uses the other gyrometers on the right joycon to detect when your ducking. It then uses the ir camera again, to look at the position of markers inside the backpack controlled by pulleys, rubber bands and string. When you pull the strings it pulls on the tab with the marker on the inside up, and the camera can see that info to tell which arm your moving. The rc car works like a hexbug nano but has dual drive lol the way the legs are shaped, the vibration makes it move forward incrementally. If only one side rumbles, it turns to ~~that~~ *the other* side. **TLDR**: This is really a kit for creating non electric peripherals that mechanically give info to the gyros and IR camera. It isn't pretending to play with that stuff you make, they interact with the joycon to become actual controllers of what your doing",
"The right side Joy-Con has a little infrared camera and illumination LED. You can see how it all works in [this]( URL_0 ) segment of the video (pause and look closely a the scenes from that point on). The moving cardboard bits have white markers attached. The camera captures an image, and the software looks for the motion of these markers to determine which pieces of cardboard have moved. It seems you can probably customize the layout of the detection (by defining rectangular regions of interest that detect when a particular white marker enters or leaves them) to build your own contraptions. Edit: Here's an [annotated diagram]( URL_1 ). For the moving \"robot\", the cardboard body is designed so that when the joy-cons vibrate, the robot moves preferentially in one direction (thanks to the angled comb-shaped \"legs\"). By choosing which side is vibrating (or both), you can steer the robot around.",
"It is using the joy-cons to their fullest. It uses the buttons (obviously), motion controls, and the IR sensor (least obviously). I'm sure they will use the HD rumble which is apparently very good, though under utilized. The IR sensor can basically read a layout of white objects in front of it (in a dark enclosed environment, especially). Think of it as reading a chessboard equivalent (it can probably do much better), and reading the positions of things in the squares. It is easy to imagine that moving one piece back and forth across one or more squares could easily be treated the same as a button push or motion control that we use so often now.",
"Remember the original Wiimote's motion functionality and its other accessories such as the crossbow, steering wheel, etc.? Well, the Labo are essentially cardboard accessories for the JoyCons that are a bit more exclusive to the compatible games. As you saw in the reveal trailer, it went to things such as a piano, a fishing rod, and a house; clearly much more exclusive accessories that work with only a single game. Maybe I'm wrong, but it's my take on it. We only had so much to work with.",
"If you watch the video closely you see that in all of the cardboard devices they Place one of the joycons in them. The joycons have gyro sensors in them and the red one has an IR sensor. These allow the movement of the cardboard devices to be translated to input for the games or applications, whatever you want to call them.",
"Labo is similar to google cardboard in the sense that the cardboard portion of your purchase simply holds your existing technology's multiple sensors (in this case your nintendo switch), and allows you engage in augmented reality play. [Here's a good demo video]( URL_0 )",
"It's just nintendo taking a bit of the virtual out of virtual reality.. Like playing counterstrike with a cardboard gun instead of a mouse and keyboard",
"The right joy-con of a Nintendo Switch has a shiny black sensor at the bottom. This sensor, when you point it at stuff, can sense the shape and distance of the stuff. Sort of like a Kinect, if you’ve ever used one of those. Piano: When you slide the right joy-con into the cardboard piano, then pressing keys down on the piano makes other things inside the piano move. The joy-con senses what those things are and, judging by the shapes and positions, the Switch is able to tell which keys are being pressed. The Switch then plays notes that go with those keys, so pressing a cardboard key makes the Switch play the note for that key. The piano is small so it won’t have as many keys as a real piano, but it’s a neat start. RC car: Both joy-cons have a rumble feature, meaning that they can vibrate. Most video game controllers have rumble features now. Most games usually use it to make the controller shake when your guy in the game gets hit, which makes it feel more real. With Labo, you attach the joy-cons to the cardboard RC car and then you press the Switch touchscreen which has touchscreen buttons for left and right. If you press the “left” touchscreen button, the joy-con on the right will shake and that’ll make the car turn left. The RC car won’t have wheels and so it’ll need to be on a flat surface to work. Will it work on carpet? I dunno, I guess we’ll find out.",
"It's a mixture of the motion sensing in the joycons and the IR camera in the right joycon for certain things like noticing which piano key is hit. There's a surprising amount of tech in those little joycons",
"How does the \"vr\" robot set work? It looks like the vr acts as a single lense piece that you wear in front your eyes so when you look at your tv it acts as a pseudo vr thing?"
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7re0ox | How does the electric company measure how much electricity you are using during different times of the day. (peak vs non peak hours) If they only read it once a month. | Technology | explainlikeimfive | {
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"If they're billing you for power you're using at different times of day then they are either reading it multiple times per day or they have a smart meter that is storing the data and being read out once a month Old power meters were dumb, they were just a dial that spun up quicker the more power you used. Modern power meters have communication built in. Some communicate via 4G and cell towers, others communicate over the powerlines using a system like TWACS. If they read your meter at the beginning and end of peak hours then they know how much you used during peak. If they use 4G to send back hourly readings then they can give you a graph of how much power you used each hour. The alternative solution is a smart meter that records the data and then someone plugs into once a month, but systems like TWACS and 4G are preferred because you no longer need a dude driving around in a truck just to read meters."
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7rfyig | Can every single thing a computer does be broken down into binary code? | When I say every single thing, I am talking about what's displayed on the monitor. Obviously the electronic signals arent in binary. | Technology | explainlikeimfive | {
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"...the signals going to the monitor are in binary. Once inside the monitor, the signals get reinterpreted by the controller ciruits, in binary and determine the brightness of each color pixel, whose data is in binary. The pixels themselves are sent binary signals. The brightness of the pixel is controlled by how long the pixel is pulsed at ON state vs OFF state.",
"Yes. The computer only knows anything as ones and zeroes. Doesn't matter what it is. There is a very complicated process stuff goes through to be displayed as what you see, but it is all stored as binary and interpreted as binary when the computer does any operation on any data. Even the operations the computer does are stored as ones and zeroes. Code is broken down from the high level languages like C#/C++/C and Java and Python, into assembly instructions which are a series of simple statements like Add, Subtract, Move Data between two locations, skip to a specific instruction, etc. Each assembly instruction has a specific sequence of bits that denotes it so the CPU knows what operation to perform. As such, there are hundreds of conventions set up as to how data/code is stored so a computer knows how to interpret it. I can try to give some examples but it might be difficult to understand or else pretty lengthy.",
"At the core of everything, a computer *computes*. This means that *everything it does* involves working with numbers. If you remember this, you can ignore \"binary code\" - that's just another way of storing numbers. If you add five and five together, you are always getting ten; even if you have to spell that as \"101 + 101 = 1010\", the math doesn't change. Binary is used **because** it's really easy to transmit as an electrical signal. All you need is two voltages (e.g. 0V and +3V) to move those numbers along unambiguously."
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7rgqci | Why do your earbuds emit a high pitched noise whenever you walk past the detectors at a library? | I was listening to music walking out of a library. Pretty much every library had those detectors near the exit to make sure nobody is leaving without an unchecked book. As I was walking past them I noticed that as I got closer to the detectors, a high pitched sound in my earbuds kept getting louder. As I walked past, it was its loudest. After going through, the sound gradually decreased. I walked through them without earbuds and there was no pitch. What is causing these detectors to emit a high pitched noise in my earbuds whenever I walk past them? | Technology | explainlikeimfive | {
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"Because the detectors transmit a signal that interferes with the amplifier in your audio player. Those detectors work in a couple of ways - One is where the signal they transmit is picked up by a coil in the book, which is connected to a small chip that transmits it's number whenever it gets power. The coils pick up this number, and the computer checks that the book linked to it has been properly checked out. The other is that the signal simply induces a current in a coil attached to the book, robbing energy from the system. The system detects this and knows that a tag is passing by. For these, the tag is either removed or disabled when the book is checked out. Both of these rely on signals that can be picked up by a simple audio amplifier."
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7rjj1b | What is community Wi-Fi and how does it work? | I've heard Cuba is doing something like an underground internet thing, and someone else mentioned it briefly on another subreddit. How does something like this work? | Technology | explainlikeimfive | {
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"The internet is basically connected computers. People can build their own internet by connecting their computers. There was a really good talk at 34c3 in germany in december 2017 explaining the internet in cuba and it's massive scale. If you are interested, [here]( URL_0 ) is the video (in english)."
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7rk5lq | How do cables like HDMI and USB keep increasing data throughput regularly while keeping similar connectors? | HDMI 1.0 had a throughput of 4.9Gbps, and the current 2.1 has a throughput of 48Gbps. How do they keep massively increasing throughput in a cable that's so similar? What's actually changing? | Technology | explainlikeimfive | {
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"The cables just carries patterns of electricity. The more important part is the stuff on the end that interprets the patterns. Newer standards can read shorter, more compressed signals. Think of it like writing on a piece of paper. With the same size paper, you could fit more data if the person writing could write very small letters and the person reading had a magnifying glass. You could fit even more data by overlapping different colors ([like this]( URL_0 )) as long as the reader can filter out one color at a time. It's all still the same sized paper, and it fits in the same envelope but one carries more data than the other.",
"Some people are saying different compression algorithms, but that would be ridiculous from an engineering perspective if your throughput is ~1000% less than the theoretical max (4.9Gb/s vs. 48Gb/s) while using the same hardware. While it is true the newer version uses a different type of encoding, the newer encoding only increases throughout by ~9%. The main reason HDMI 2.1 is faster than HDMI 1.0 is because of 4 data channels as opposed to 3 data channels, and a higher clock speed (12GHz vs. 0.165GHz). With HDMI 2.1, you have a theoretical max of 12GHz * 4 = 48Gb/s. However, even though you are transferring 48Gb/s, only ~42Gb/s of it is actual usable data. This goes back to the encoding mentioned previously. HDMI 2.1 uses 16b/18b, which means that for every 18 bits sent, 16 bits of it are the actual data. HDMI 1.0 uses 8b/10b, which means that only 8 bits are actual data for every 10 bits sent. So the encoding accounts for a small increase in throughout (89% vs. 80%), but as you can see, this is not the main reason for the increased throughout going from HDMI 1.0 to HDMI 2.1. USB 3.0 also uses 8b/10b, so you only get about 4Gb/s of actual data as opposed to the 5Gb/s listed. USB 2.0 used something an encoding called NRZI, which has no negligible overhead. However, USB 3.0 has complete different hardware to allow backwards compatibility and full duplex as opposed to half duplex in USB 2.0. With half duplex, you have to transmit and receive on the same wire. Full duplex adds another set of wires so each set can be used for just transmitting or receiving. These are the main reasons USB 3.0 is faster than USB 2.0. Source: Wikipedia and currently studying computer engineering",
"In the case of USB the cables are not the same, they just appear similar. USB 2.0 has 4 pins. USB 3.0-b has 11 pins USB 3.0-a has 9 pins USB-c has 24 pins.",
"For USB, there are physical changes. URL_0 HDMI, there is no difference except between Cat 1 and Cat 2 (high speed) cables. There's no such thing as an HDMI 1.4 cable or an HDMI 2.0 Cable. URL_1"
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7rplek | How will the many tiny amounts of cryptocurrencies left in users wallets after transactions affect the respective currencies over time? | I'm guessing there are thousands/millions of other tiny amounts of BTC/ETH etc left in user's wallets that are simply too low in value to recover. Over time will this further reduce the amount of each crypto currency? Has this been factored into the cryptocurrency technology or are we generally still in uncharted territory when it comes to crypto? | Technology | explainlikeimfive | {
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"This is a problem, because each wallet with funds in (even 1 satoshi or similar minimum multiple) has to be indexed. In general, this index has to be held in RAM on every computer running the cryptocurrency software. For bitcoin, this is a big problem, as the list of wallets with funds (the UTXO set) needs hundreds of MB of RAM. In the case of bitcoin, many of these funds are \"trapped\" due to high transaction fees, and there is no way to spend them or merge them into more compact wallets. The result has been that the size of this UTXO set has been growing rapidly. In contrast, for cryptocurrencies with much lower fees like bitcoin cash, the UTXO set is much smaller and hasn't been growing, because it is cost effective to use these small wallets. We are still in early days, but one of the ways that this is being dealt with in bitcoin is to charge users a \"small payment fee\", to make sure that a newly received payment is always big enough to spend. For example, if a shop wants to sell a $20 item with bitcoin, they would add a $10 \"small payment fee\" to take the value up to $30. That extra $10 would cover the bitcoin transaction fees needed to merge that payment into a more compact wallet. Effectively, it is a way of getting the buyer to pay 2 transaction fees - 1 fee to pay the seller, and 1 fee to allow the seller to spend the payment.",
"In Bitcoin the smallest possible unit is a \"Satoshi\" which is one hundred millionth of a single bitcoin (0.00000001 BTC), and in Ethereum it's called \"Wei\" and it's even smaller (0.000000000000000001 ETH). So if you have a tiny amount left in your user wallet, you can use it as much as you could use e.g. 1 cent. You wouldn't be able to really do/buy something with it, but you could still gift it to someone, or keep it until you collected 20 cents and then buy sweets with them. Of course, if many people have tiny amounts of cryptocurrencies left in their user wallets, and if they don't do anything with it, you could say it's \"lost\" money. However, that's the same when real coins are lost in the sofa and they are never recovered, because you gave it to waste incineration. The bigger problem occurs when people loose their private key to their wallet, because then they can't access it anymore. This means the cryptos stored on the wallet are inaccessible, which means the money is lost. So tiny amounts left in wallets don't affect the cryptocurrencies if the owners still use them. Lost private keys do."
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7rs9cx | How does sandboxing (computer security) work? | Technology | explainlikeimfive | {
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"Say you are hosting a fancy dinner party in your back yard and your sister brought one of your nephews along. This young child needs to do something to be entertained but you really don't want them bothering your other guests. So what you do is give them a sandbox to play in. They can do whatever in the sandbox but they aren't allowed to leave or access anything outside the box without using standard methods. They can ask for juice but not cake. In computer security it is much the same idea, where applications are given a set of resources to use and standard methods of interaction. They are not allowed to do whatever they want in order to prevent misbehavior.",
"You give a program a set of resources to use, and you tightly control any access beyond that. For instance, you might let the program only use a very specific folder on the disk, and if it wants to access other folders, you would not allow it (or you would show a prompt for the user to confirm it). The quality of the sandbox matters. A sandbox with a bunch of bugs in it is going to allow clever programs to do things that they weren't intended to."
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7rtcnh | How does Netflix take up so little mobile data compared to other streamers? | Technology | explainlikeimfive | {
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"Some phone plans let you stream Netflix for free. I have mobile and can watch Netflix constantly and it not effect my data usage",
"Really good compression, though i think you overestimate the data consumption of youtube and underestimate how much data you've used [Netflix estimates]( URL_0 ) data consumption for each quality setting, even at Low(~480p) you're looking at ~300 MB/hour so you either watched a short season of Breaking Bad(one of the 8s or the 7) or you've miscalculated the data consumed. A 13 episode season of Breaking Bad at 42 minutes per episode should consume 2.7 GB of data If you were to watch youtube videos in 480p for the same amount of time it would consume roughly the same amount of data, but you likely watch your youtube videos in higher resolution which means more data and gets you a skewed perception on data usage For the most part, two videos of the same quality streamed from two different places will consume about the same amount of data. The same quality is the keep phrase in there, if you have something streaming 4K and something streaming 480p then it won't be close to even."
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7rtipy | How were cartoons in the early 2000's animated? | For example, when the characters are talking, only their mouth may move; however, how did the animators do this without redrawing everything in the frame? Did they have something like photoshop where they could change small details while leaving the background the same? | Technology | explainlikeimfive | {
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"I think a layer of clear plastic over a background. They'd just draw the mouth each frame on that later and have the background.",
"In traditional animation, be it from 1995 or 1935, multiple layers of clear plastic film are stacked on top of one another. Each layer, or cel, might have a single character or maybe just a character's head or arm. That way the characters can be drawn independently from each other and the backgrounds. It is still a very labor-intensive process; at that time it would have probably been outsourced to East Asia. Although the early 2000s would have been the beginning of computer animation, so who knows.",
"In the early 2000's, it was pretty normal to have pencil drawings imported to a computer and colored digitally in a preferred program chosen by the studio. Usually the poses of the characters would be chosen by the studio over here and then that would be sent overseas and then all the in between drawings would be sent over here to be colored and finalized."
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7rui24 | Numbers Stations | Technology | explainlikeimfive | {
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"> Numbers Stations Numbers stations are radio stations which will frequently read out a series of numbers in sequence, often by a robotic voice and at varying times. The purpose of these stations is uncertain but generally considered to be a method of communicating to spies by encoding secret messages in the sequences of numbers. Which governments operate these stations can generally be inferred by the territory in which they reside, but the content of the messages is of course unknown.",
"Yo ho ho! Yer not alone in askin', and kind strangers have explained: 1. [ELI5: How do numbers stations broadcast and how are they able to do it for so long without breaking down? ]( URL_0 ) ^(_2 comments_) 1. [ELI5: Numbers Stations ]( URL_3 ) ^(_1 comment_) 1. [How can a numbers station function as a dead-man switch for nuclear weapons? ]( URL_1 ) ^(_3 comments_) 1. [ELI5:World War 1 / 2 Number Stations - What were they used for? ]( URL_2 ) ^(_4 comments_)"
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7rvk5d | How do internet searches work with non-Roman characters? | For example, a Google search for "Koda Kumi" will produce different results than the same name in kanji as "倖田 來未". How does a search engine interpret these characters and find relevant results? | Technology | explainlikeimfive | {
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"> How does a search engine interpret these characters and find relevant results? A search engine doesn't care what the string of characters are that it is matching. It could be matching real words or nonsense strings, and as long as it recognizes the kanji as characters then it will work just fine. More complicated would be for the engine to draw connections between the English version of the kanji sequence and return similar results for either one."
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7rxvov | What causes CRT TV's to blop away when turned off? | Technology | explainlikeimfive | {
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"I assume you mean how the edges appear to kind of come slamming down into the middle. Its probably due to the fact that there are two capacitors that are in control of the horizontal and vertical synchronization of the electron beam. As the capacitors are charged and discharged the beam moves from left to right very quickly as the vertical capacitor allows the beam to go up and down a little more slowly. When the power is turned off the capacitors take time to discharge. As they discharge the natural state of the electron beam is pointing to the center of the screen. So it appears as the lighting of the screen comes crashing toward the middle. Really you are watching the two controlling electronic devices power down, lose their charge, so the beam begins to only illuminate the center of the screen.",
"Inside the CRT is a beam of energy that illuminates whatever spot on the inside of the screen that it touches. There is also a device that directs the beam magnetically called a deflection yoke. When the TV is on, it directs the beam to scan back and forth and up and down to make it illuminate the back of the screen in a bunch of rows. When you turn the TV off, the yoke powers down faster than the energy beam, so it quickly starts moving the beam less, and the beam draws smaller and smaller sets of rows until it just gets to the single point at its natural resting place."
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7rxx1x | Why is it still a challenge for some countries to build ICBMs while US/USSR could already do it in the 50's? | Technology | explainlikeimfive | {
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"ICBM technology requires an extremely advanced research and development basis in aerospace engineering and rocket science. Which in turn requires strong institutions specializing in physics and mathematical research. But that strong research basis will only get you the theory and design because engineering a rocket requires that your country also have a manufacturing sector that includes the skillful production of precision instrumentation, specialized machinery, advanced application of metallurgy, and chemical processing for fuel and lubricants. Which, by the way, requires even more knowledge and research to implement because all those necessary requirements would take decades to develop. But that's not all, guidance systems require that your country also have an advanced electronics industry capable of producing components that can withstand conditions normal electrical equipment would simply break down mid trajectory. Now, you can shortcut this extremely complicated process by buying and importing all those things that are necessary for the development of ICBMs, which is what North Korea did. But that still doesn't take into account the expertise and infrastructure you need to test and produce a viable system. The ICBM still needs a warhead which has its own development process, but actually relatively easier than producing the delivery system. So the countries that developed ICBMs are countries that had the foundation prior to their goal of producing ICBMs. The United States, and the Soviet Union, already had a strong industrial base and scientific research community to lean on to develop their ICBMs, not to mention that they both were able to acquire expertise and know-how by importing former Nazi scientists and capturing the research the Nazi regime made in developing their own rocket technology. Germany was (and still is) a great scientific and industrial center. Many countries even developed and advanced economies, lack ALL the components required to develop ICBMs. Even developed countries that do have the necessary factors to develop ICBMs choose not do so because the allocation of resources toward the goal of producing an ICBM would be economically ruinous for their country and result in major hyperinflation and suffering. It would take years and the resources put into developing an ICBM would be resources wouldn't pay for a national healthcare system, public education, retirement payments, etc. So many countries simply ally with the US and sign treaties asking to be under the protection of their ICBM program, for example, NATO. And those countries also agree not to pursue technology like that under international treaties at the behest of the superpowers.",
"Because most countries aren't in the 1950s yet, in terms of their ability to create new homegrown technology. Sure, they have cell phones and computers, but they didn't make them, and even if they did, they didn't come up with the technology, they got it from technologies other countries gave or sold them. In terms of pure homegrown technical capacity, many countries couldn't even make airplanes. And since ICBMs and nuclear bombs are closely guarded secrets, that is the one thing they do have to start from scratch with.",
"The US and USSR both devoted enormous portions of their national resourses and both were large countries with hundreds of millions of people and rich in natural resourses. The difficulty of making ICBMs is controlling an explosion, which is never an easy thing to do even if another nation has done this in the past.",
"The amount of effort and budget the USA and Soviets put into it were absolutely huge. Other countries will have less budget thus less developments slowing the proces. Also the resources and equipment are strictly managed (paints that withstand the force, rocket fuels, specific technologies) making them unavailable or scarce for other countries again slowing developments or even making it impossible. Also, sabotage is a real thing, stalling developments etc.",
"First and foremost it's important to recognize that almost 200 countries at the UN have accepted the [Nuclear Non-Proliferation Treaty]( URL_0 ), which stipulates that a country should only pursue nuclear technologies for peaceful purposes. You have a country like North Korea, for instance, that withdrew from that treaty in 2003... The country itself is already plagued by a lack of resources to take care of its populace adequately, let alone pursue a very high-tech missile program (when the majority of its military equipment is already decades old and not serviceable). ICBMs and the nuclear technologies used on them require a lot of high-precision instrumentation and rarer resources that take money and other resources to produce and which are not just readily available on the global market (especially when everyone has sanctioned you and is explicitly stopping you from importing such resources). In reality, the money aspect is a huge part of it, and a lot of countries just don't have that kind of money to invest in such lengthy projects."
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7s0vl5 | how did ancient cultures create statues of solid gold? Is it shaped or or made from a mold? | Technology | explainlikeimfive | {
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"Due to the rarity and cost of gold, it wasn't common for solid gold items to be made, except for small jewelry type items. And of course, if such things were created, they were subject to the theft and re-melting over the ages. The melting point of gold is close to that of copper, and it's possible to melt either metal in a charcoal furnace with forced air from a bellows. The simplest casting method would be to carve a small master pattern die from wood or bone. The master could then be pressed into a block of wet clay forming a mold. Molten gold would then be poured into the mold cavity. Two sided molds could also be created with the same method. Because of the softness and malleability of gold, you can also form gold items just by hammering gold nuggets or small cast ingots, with various punches and chisels. This is probably the first method used to work gold, before casting was used. Another process developed in the bronze age is lost-wax or investment casting. This was also common for creating bronze tools and weapons, as well as sculptures and jewelry. Adapting it for gold isn't a problem. In this process a pattern or investment is carved from beeswax, tallow, or resin. The pattern is coated in successive layers of fine clay, mud, sand, and other materials, until a thick outer shell mold is created. Alternatively a clay core can be created, and the core can be coated with several thin wax layers, then fine details are carved into the wax. Finally the outer supporting mold is created. This saves on the amount of metal in the final casting. The finished mold is then heated to melt out the wax or resin, leaving a hollow mold cavity that very precisely duplicates the features of the wax pattern. This is then filled with molten metal, cooled, and the outer shell is broken out. This is called investment because both the original wax pattern and the outer mold is destroyed. This technique is so effective and can create intricate details that other manufacturing processes simply cannot produce. It's still very popular today in the 21st century."
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7s5yl3 | How does compression clothing work and why doesnt it cut off blood circulation, especially on pieces like socks? | Technology | explainlikeimfive | {
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"I wear compression clothing for health reasons every day and I can answer with certainty. There are two types of compression clothing: one is for athletic performance and the other is for medical necessity. There are distinct differences between the two. Athletic compression is basically a placebo except when lifting heavy weights. It does not get tight enough to produce any effects while the user is wearing the garment. It helps circulation after working out but there has been no scientific evidence to show that it helps during a workout. It makes the muscles feel tight, which DOES help produce short bursts of muscle strength but does not help with running. Medical compression is much tighter. So tight, in fact, that you need a prescription from a doctor to purchase it. What these do is tighten your fat and muscle so that it improves circulation. This helps prevent blood clots and aids the lymphatic system in removing waste. Medical compression socks go to your toes whereas athletic compression only goes to your ankle. If you needed medical compression and only wore athletic compression your feet and ankles would swell up to a dangerous size. By going to your toes, the medical compression makes sure nothing gets \"stuck\" down there."
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7s6slx | What happens to electronic hardware when stressed constantly over a relatively long time | Technology | explainlikeimfive | {
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"text": [
"Silicon components develop a variety of defects when under use. ELI5 Explanation: Much like a river picks up sand and deposits it somewhere else, current moving through silicon tends to pick up material and deposit it elsewhere, this eventually causes the circuit to malfunction, heat can make this worse as hot substrate can become dislodged more easily. More detailed explanation: One such type of wear is electromigration, whereby metal is carried to where it shouldn't be URL_0 Another kind of wear is hot carrier injection, whereby charge carriers are embedded where they shouldn't be. URL_1 These effects eventually prevent the transistor from switching correctly, or as fast without increased voltages. Increased temperatures generally aren't responsible for mechanical failure perse, but increase the incidence of the above (And other) mechanisms of wear and tear on the substrate It's also worth mentioning that when sitting around and doing nothing, high energy particles, gamma rays, background radition, can also cause hot carrier injection, and other damage to the electronics. So the device will even degrade when sitting around and doing nothing. People living on high mountains will experience more degradation due to increased incidence of cosmic rays, people living near sources of natural radioactivity will also experience faster degradation."
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7s8d0e | Why do musketeers have swords instead of muskets? | Technology | explainlikeimfive | {
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"Musketeer literally means \"person armed with musket.\" And in a big-time, army-on-army battle, they'd be the ones firing muskets into the other guys. And they'd have a sword as a backup in case they ran out of ammo or had a malfunction... or the other guys got close. But the Musketeers made famous by *The Three Musketeers* were part of a group called the Musketeers of the Guard, who were basically the royal guard for the King of France. The problem with a musket was that it wasn't very accurate. Like at all. And they take a while to reload. Like minutes, not seconds. Which is fine when you're shooting into another army, because you'll probably hit *something,* and you can probably get a few shots off. But when someone's trying to attack your king, or when you're fighting a nice swashbuckling duel in a book, the cleanest way to take out the bad guy was still a sword, until better firearms were developed. And since that's the kind of stuff that's happening in the book, that's the image we have of the Three Musketeers.",
"Musketeer is literally the word to describe a soldier equipped with a musket. Anywhere you see a musketeer without a musket, it has either been disarmed or tossed away during close combat."
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7scfaq | How did they edit people out of really old photos like Stalin did? | [Example I was referencing] ( URL_0 ) | Technology | explainlikeimfive | {
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"URL_0 The top comment explains it really well: > In the old school Stalin era you are asking about, a typical method was to take the original negative and then print the photograph in large format. Then, an artist could use a scalpel to carefully cut out the specific offending individual (or inanimate object, such as a billboard or sign) that they wished to be removed from the original scene. This method was a lot easier than trying to do this same technique on the much smaller original negative. > Then, they could either insert another cutout of a similar scaled and lit person or object to fill the void from the original cutout, splicing that new subject/object into the picture. Alternatively, or even in addition to, they would use airbrush and painting techniques to cover up the person by painting in a new background. > Once the artist was comfortable with the appearance of the coverup in the now-censored full size airbrushed photograph, they would then take another camera and carefully frame and take a new picture of the old doctored photograph - basically, taking a picture of a picture. This was an important step because not only would this act of taking a picture of the doctored photograph help hide any small blemishes or imperfections from the censoring job (allowing them to blur the focus slightly during the reshoot for example, or use different grained film to help with the blending), but this act would also produce a brand new \"clean\" negative of the original photo that could be used to replace the old \"evil\" negative in the archives. Credit /u/Falcon109",
"Many of the tools in Photoshop have a real world analouge, like cut, copy (but not the clone tool), smudge, airbrush etc."
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7scz10 | how do pagers work? | I was born in 1997 right when pagers were dying out and cell phones became accessible to everyone. I can remember things like VHS and walkmans but not pagers. I understand that it’s a means of one way communication, but I fail to see how it’s not texting? Are there preset messages or are they customizable? How exactly does the sender send a message to the receiver? | Technology | explainlikeimfive | {
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"They're more like a walkie-talkie than a cellphone. They receive on a radio frequency, sent by a base station (or multiple overlapping areas served by multiple stations) Often you send a message with a telephone, which goes to the base station, that then sends out the message via radio. Most pagers use only numerical messages but more advanced ones can send short text messages. some are even two-way, allowing a message to be sent back. A typical message to send to a pager would be a phone number or phone extension, and the person receiving the beep can then use a landline or cellular phone to return the call. Edit: use a pager every day at work, we only recently replaced an old analog keypad with a dedicated handset telephone for sending numeric pages.",
"History: First you had the [original type of pocket pager]( URL_2 ). Call a toll-free phone number, it would prompt you to enter your call back number, and then hang up. The pager would display that call back number and that was it. Single line LCD display, usually not even backlit. Then you had [text pagers]( URL_3 ). These could receive numeric pages like the OG model, but to send a text message you called a call center, who would type your message in for you. Usually 2-3 line LCD display, usually backlit. (Edit: I worked in one of those call centers for a few months. It sucked.) Finally, we evolved to [2-way pagers]( URL_0 ), the most famous being the Motorola. These had a keyboard and you could type messages back and forth. This was a specialized device that did nothing but the equivalent of SMS on your cell phone today. (Edit: my first pager was a 2-way, around 1998 when I got my first IT job). There were even tributes in songs to the Motorola 2-way pager. Like this line from Jay Z: URL_1 A 2-way pager was a status symbol back in 1999, right at the height of the dot com bubble euphoria, but before we really knew what to do with the internet yet. [Motorola webpage from March, 2000]( URL_4 )"
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"http://www.pagenet.ca/wp/wp-content/uploads/2010/11/0004_Motorolla_PF1500.jpg",
"http://web.archive.org/web/20000301035454/http://commerce.motorola.com:80/consumer/QWhtml/pager_cat.html"
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7se8a5 | Are internet backbone providers allowed to prioritize the traffic and interconnections of different ISPs the way ISPs are planning to do the same with content providers? | Technology | explainlikeimfive | {
"a_id": [
"dt45l4o"
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"text": [
"Yes. In fact, this was also allowed under the 2015 net neutrality rules; thise rules only regulated Internet service provided to individuals, small businesses, schools, libraries, etc. The ISP-to-ISP market is much more competitive, so the FCC hasn’t ever felt like it had to be heavily regulated."
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7sfpw6 | How do emergency responders get access to gated communities & other restricted areas. | Do they have a list of all the codes or a master unlock of sorts? | Technology | explainlikeimfive | {
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"text": [
"One of the most common ways is the use of a Knox Box. It's a small metal lock box. The first responder has a key to the box, and the keys to the building are inside. Google Knox Box, and you'll see what they look like, and you'll start seeing them everywhere you go.",
"There is no one-catch all solution. It would depend on the community and jurisdiction: 1. The access mechanism has a built-in bypass for emergency services; 2. The community or area has 24/7 staffing to let in emergency vehicles; 3. The emergency service contacts, directly or indirectly, the security service for the area they are trying to access to let them on; 4. They break in;"
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7sgyz7 | How can 100 million people browse porn videos at the same time but I'm still in queue to start up Overwatch | Technology | explainlikeimfive | {
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"text": [
"because when you watch porn. it's a 1:1 connection between you and the porn server. when you queue to play overwatch, they need to find 9 other people with similar skill rating as you. so that could take additional time.",
"How can 100 million people be calling each other at the same time, but I'm still in queue to talk to my company's tech support? They have nothing to do with each other.",
"simple. there's alot more money in IT operations porn than there is for overwatch. most people don't know this...but alot of IT innovation is driven by the porn industry. about 30% of the entire internet is porn. for every overwatch players, there's at least 1000x that in porn visitors .",
"That's like asking how can 100 million people be eating but why am I still in a 20-minute wait for the cheesecake factory",
"For the same reason a traffic jam on one highway has no bearing on all the other highways. You're stuck in traffic going to L.A, and asking why the guys in Denver and Washington aren't having problems.",
"Because there aren't 100 million people accessing the same porn server at the same time. There are thousands/tens of thousands of people trying to access any particular Overwatch server at any given time.",
"Porn servers are like a multi lane freeway built to handle that kinda traffic every day. Overwatch servers are like that single-lane suburban side street that everyone suddenly wants to drive on because they put URL_0 in a cat suit ;).",
"How do you think those things are at all related ?",
"Imagine Overwatch like you're waiting in line for something. Before you're allowed to enter they have to make sure you're who you say you are and that you're allowed in. Once you're there you're free to do whatever you want. But with porn it's just like a giant store you can run into and look at anything you want. With a stoned security guard out front barely checking ID's and not really caring what happens once you're in."
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7sk9lx | Why aren’t more major electronics companies making video game consoles? | Technology | explainlikeimfive | {
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"The cost is way too high for the profits available. You have to invest huge sums in games and then make profit from selling hardware at very low margins. It's more a question of why anybody is still making consoles.",
"There is almost zero profit in consoles. They are loss leaders. For a while, Microsoft was losing $100 for every XBox sold, but they try to make it back with games. So unless you own a crapload of game studios, it's not worth it to make the hardware.",
"For a console to be successful, it has to have a large following, and a lot of development behind it. That’s hard to create from nothing. Also, most people only have room in their lives and budgets to devote to one console. A customer that has put a lot of $$$ into one console usually can’t afford to do the same with another, and has less incentive to do so. What you see (PS, Xbox, Nintendo) are the three current exceptions to the rule that creating a console is damn difficult. It’s a lot like smartphones and why they quickly converged on just two major players. It’s no coincidence that both were created by huge corporations with a solid vision and a crapload of resources to risk on the venture.",
"First, creating a console takes a lot of time and money. If they don't sell enough, they lose lots of money. They have to compete with other consoles that exist. Are you going to buy a PlayStation, an XBox, or a Huawei JoyMech? All the companies making games? You're saying they need to translate games even more. It already takes time and money to translate a game from Windolish to Xboxese and PlayStationian. Now they have to translate it into JoyMechan as well? OUYA tried doing this halfway. It used a language that was already out there (Android) and simply made things show bigger on a TV and use a consult controller. It still failed, badly. Barely lasted 3 years. The problem? Nobody wanted to make games for this new thing. Nobody wanted to make games in a new language. Not enough people wanted to buy the new thing instead of another Xbox. And there wasn't enough people using it to make high enough sales and make money."
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7skvl6 | How did interface(Sites, UI) designs get switched from non-flat to flat designs that we see in modern interfaces? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"I'm gonna assume you're asking \"why did we go from one art style to another\" So, computer graphics started very simple, because the computers didn't have enough memory to do much better. If you look at Windows 3.11 everything is just boxes, then when you get into Windows 95 you get stuff that looks a little more detailed, with some cute shadow effects on the bottoms of buttons to make them look 3d. Give it about ten more years and you're looking at Windows Vista's GPU-accelerated 3d floating transparent Windows. So \"why did we make a complex art style style?\" Because they could, and it made people go buy windows because pretty. But why'd we go back the other way again? It turns out once you introduce crazy 3d window and stuff...it looks cluttered. Simple boxes actually do a really good job communicating what is and isn't important if you have good design. Agruably, they do **better** at immediately highlighting what's important than lots of fancy details the viewer has to mentally crunch. So Win10 and so forth got simpler, because that's more functional to actually use, and people aren't as wowed by 3D graphis anymore."
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7sla6b | How are people creating their own internet? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Take two computers, run a cable between them. Now the two computers can talk to each other. Poof, you have a network. You can stick a switch in the middle and connect more than two computers even. Just give each computer a unique name (or number, let's do numbers because those are easier for computers) so when you send a message to another computer, the other computers know which one you want to talk to. So now you have a local area network. Let's connect it to some other networks. Run another cable out the door, down the street, and in to the center of town. Place another switch. Let other people, running their own networks, connect to that switch. You need to do some coordinating to make sure everyone's names are all unique, but other than that, they should just be able to talk to each other. Then make it even bigger, by connecting the network at the center of your town to the networks at the centers of other towns. Run some cables across the ocean, or launch some satellites and communicate through space. Now you have your own global Internet."
],
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7smasq | When viewing a lengthy video on YouTube, how does YouTube know where to place the ads? | I was listening to a full album on YouTube and ads were always placed in between songs, not during the songs themselves. How does YouTube know and determine advert placement? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"If you are talkign about the banner ads which appear over your video then the position of those is set by Youtube and you cannot change them. What you can do though is set ad breaks in your video where your footage will stop and an ad will appear. Its very much like TV when a presenter says \"And we will be back after this break\". If your videos are not too short (Youtube has rules about how many ad breaks can go in compared to the length of a video), then setting an ad break like this can be the most profitable way to place ads in your footage. If you access the video editor and click on the 'Monetisation' tab you will see at the bottom of the page a slider for 'Ad breaks' You need to have the option clicked for Skippable video ads above it but once you have you can choose whether an ad will appear at the start, the end or somewhere in the middle, and the longer your ad is, the more ad breaks you can put in. TLDR: The creator can set where the ads go."
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7sn27n | Why were straws invented? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"From what I'm aware of, straws were invented in order to avoid the residue at the bottom. They were first invented to drink beer (by the Sumerians I believe) - and used so that the consumer would not end up drinking the byproducts as well (which would accumulate at the bottom). The more modern straw was invented because prior to it, straws made out of grass were used and coming into contact with a liquid would make them soft/pulp-like thereby rendering it useless. There's an article on The Atlantic that traces the origins of the straw that might fit your question more. Im on the mobile for now, will link it once I'm on the PC.",
"Drinking glasses and cups are designed to be, among other things, easy to manufacture, easy to clean, and structurally sturdy. Unfortunately the confluence of those design parameters makes them not quite optimum as a means of delivery of liquids into the human mouth. They're not that bad, but not perfect. They need to be held up to your mouth and tilted when you drink. The flow is not completely controllable. It's difficult if not impossible to get a clean seal along your bottom lip because of the curve. A drinking straw is a specialized add-on device that provides a more optimized drinking process. It provides a clean, completely airtight seal which makes the liquid delivery more efficient and less prone to spilling. You can just leave the glass sitting on the table as you drink from it. You can get at the liquid somewhere besides the top. And it allows two or more people to drink from the same vessel simultaneously. In return, a straw is (usually) disposable (wasteful) and difficult to clean if the liquid is viscous."
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7so70b | If my YouTube video has already buffered, why does it have to re-buffer if I click back in time? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"A segment of video is stored in memory. Usually only the segment you're currently watching is stored. Anything past in the time line is unloaded again to free up memory for loading up the upcoming parts of the video. If you jump ahead or back, you're requesting a piece of video that is no longer in memory so it needs to be loaded once more. It's kind of like walking along the pavement while you only have 3 pavement stones. The one you're standing on, the one in front of you and the one behind. As you walk, the pavement stone behind you is removed and put in front of you. If you start walking backwards, the stone ahead of you will have to be put behind you again.",
"I miss the old YouTube system when you could buffer the whole video. I wish they would at least include it as an option."
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7sp9e0 | what is thread-concurrency? | I'm experiencing a lot of hardware errors while mining and have read that it might be due to the thread-concurrency, but I struggle with understanding exactly what thread-concurrency is. | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Thread concurrency is when multiple threads are running at the same time. Idk if the same principles apply for software and hardware, but at least in software, concurrency introduces problems that normally wouldn't exist. Let's take the example of ATMs that digitally records how much money my bank account has. Now let's say I access my bank account from two different ATM's at the same time, and make a withdrawal from both. I have 3000 dollars in my bank account initially, and I make two withdrawals of 300 dollars simultaneously. Let's take a look at what happens normally (if I had made two withdrawals consecutively instead of simultaneously) and what happens when concurrency happens. Normally: 1: ATM queries my account, and sees I have 3000 dollars 2: ATM sees I make withdrawal of 300, subtracts 300 from my total 3: It stores my new value as 2700 4: ATM queries my account again, and sees I want to withdraw another 300 5: It subtracts another 300 6: It now stores my account as 2400 dollars With concurrency, now two ATM's are simultaneously accessing my banking information. Based on the OS implementation, we do not know when the threads switch, which means we do not know when ATM1 queries, when ATM2 queries, when ATM1 does the withdrawal, etc etc relative to each other. What could happen is: 1: ATM1 completes everything, 2: ATM2 completes everything. Which gives the correct outcome anyways. But that is rare. What could happen is: 1: ATM1 could query that I have 3000 dollars, and does the subtraction 2: ATM2 queries my bank account, and sees I still have 3000 dollars, because ATM1 hasn't had a chance to update my balance yet 3: ATM1 updates my balance to be 2700 4: ATM2, given that it read 3000 as my balance, also reaches 2700 as my final balance, and writes it to my bank balance 5: My bank balance is now 2700, even though I withdrew 600 dollars These kind of errors are thread-concurrency errors"
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7sqsfw | How do surgeons prevent major blood loss during coronary artery bypasses? | If at some point during surgery a hole is made in the aorta so you can bypass a clogged heart artery, how do you prevent blood from spewing like a fountain out of the aorta? | Technology | explainlikeimfive | {
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"text": [
"It is clamped. The heart is then stopped with a potassium solution (many potassium solutions such as KCl can cause cardiac arrest, which is used in lethal injections!). The sewing of another vessel is performed, then the heart is eventually started once again.",
"Blood flow is diverted to a heart-lung machine during surgery, which allows the heart to be stopped and operated on."
],
"score": [
6,
3
],
"text_urls": [
[],
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} | [
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7srkcl | How does an authenticator app work? | With the release of 2FA today, this is on everyone's minds. | Technology | explainlikeimfive | {
"a_id": [
"dt6yowg"
],
"text": [
"> How does an authenticator app work? The idea behind an authentication app is to have an algorithm with two inputs: A static secret key and a publicly known, changing input. The output of this algorithm does not reveal what the secret key is from its output. Both the server and the legitimate client have the secret key, and the publicly known input is typically something like the exact time of the requested login. When the login is requested both the server and the client run the algorithm with the agreed on public input and come out with an answer; if the client's answer matches that of the server then they can be sure the login is legitimate. An observer who is up to no good would see that exchange but from the answer would have no way of determining the secret key. If they tried to log in later the time would be different so the old answer wouldn't work, and there is no way to predict what the new answer should be from the old answer. Every legitimate user would have their own secret key which makes the overall algorithm capable of being used for anyone."
],
"score": [
14
],
"text_urls": [
[]
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} | [
"url"
] | [
"url"
] |
7sssjr | If we can colour calibrate our computer monitors. What is the point of paying more for the colours being "accurate" | Technology | explainlikeimfive | {
"a_id": [
"dt78u16"
],
"text": [
"Not all monitors can be calibrated to within a reasonable degree of accuracy, especially if they're cheap monitors."
],
"score": [
6
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
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|
7stagj | How Muography works to look inside things (like pyramids) | It seems nuts and I wish I could wrap my head around the concept. | Technology | explainlikeimfive | {
"a_id": [
"dt7bk6b"
],
"text": [
"It functions almost identically to an x-ray In an x-ray you have a source that is blasting x-rays through the item you're interested in and towards a detector which shows you where it did and didn't detect x-rays making it though Muon tomography uses muons instead of x-rays because muons can penetrate deeper. The muons are formed when super high energy cosmic rays hit the atmosphere and form pairs. The muon source is the sky, the object blocking them is the pyramid, and they've got a special detector that tells them what direction it came from and with how much energy. Particles with less energy passed through more matter There's a computer to crunch the numbers to turn their individual x-rays into a CT scan to show the 3D nature of what they're studying."
],
"score": [
4
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
7sti5v | How do radios stay connected to a radio station even though the frequency of the broadcasted wave changes? | For example, let's say I tuned in my radio to 100.0 FM radio station and it plays[ this wave]( URL_0 ). The frequency of the wave being broadcasted changes, so why am I still connected to 100.0 FM radio station? I feel like I am misunderstanding this. | Technology | explainlikeimfive | {
"a_id": [
"dt7cz11"
],
"text": [
"The waveform is superimposed on top of a sine wave at 100 MHz – this is called modulation and the channel frequency is a called a carrier frequency. If you looked at the frequency of the overall signal, you would see a big peak at the carrier frequency (100 MHz in your case) and a bunch of other frequencies below and above the carrier, changing with time. The frequency range is limited for each channel and channels are spaced far enough apart so their signals don't interfere with each other. Your radio is tuned to the carrier frequency of your chosen channel and then decodes the signal superimposed on the carrier signal. Edit: for added clarity here is a lower-level reply from /u/dmukya: > the waves [the carrier and the signal] are combined in a process called Hetrodyning. Your radio itself is \"tuned\" to the big wave, and sends everything that isn't the big wave to the audio circuit for playback."
],
"score": [
10
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
7stplc | If a car can run for years on a car battery by recycling energy through an alternator why can’t we develop an “alternator” for your home to reduce energy consumption? | Technology | explainlikeimfive | {
"a_id": [
"dt7e13g",
"dt7ebap",
"dt7efo5",
"dt7mr58"
],
"text": [
"The alternator in the car does not reduce energy consumption. It consumes energy generated by the engine and transforms it into electrical current. Some of that current is used to recharge the battery, the rest is used for all the car's electronics.",
"Cars burn gas to run the motor, which drives the alternator, which is basically just a couple magnets spinning inside a large coil of wires. This magnet and wire design is commonly called a generator, its where the wires outside your house actually get the power from.",
"The alternator on a car is a tiny electrical generator. It isn't recycling energy, it's stealing energy from the engine (which burns gas) and converts it into electricity. While the car is running, all of the electronics should be powered by the alternator, not the battery - the battery is only used for starting the car & running it while the engine is off. You can't just place an alternator in a home and expect it to do anything. For it to generate power, you need to have something turning it - like a gasoline engine. While you can buy gasoline-powered generators for your home, they're significantly less efficient (and thus more expensive) than the large generators the power company runs.",
"You can get them - a search for \"portable generator\" will turn up many examples. But you wouldn't usually use one to power your home, because electricity from the grid is cheaper than the fuel to run the generator would cost. Generators are used where no grid connection is available, such as in a moving vehicle."
],
"score": [
27,
12,
7,
3
],
"text_urls": [
[],
[],
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
7stze2 | how does Samsung pay work? | How does the technology work? And how is it different from Apple pay, Android pay, and all the rest? | Technology | explainlikeimfive | {
"a_id": [
"dt7j7fa"
],
"text": [
"Samsung Pay works by emulating the magstripe on your registered card, so in essence it tricks the card reader into thinking you swiped an actual card. It's called MST. This allows you to use Samsung Pay in nearly any store, even ones with older card readers (like in small mom and pop stores). Apple and Android pay require NFC *for purchases in physical stores*. You can buy online with all 3 payment systems."
],
"score": [
3
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
7su189 | Why have Facebook, Instagram, and Twitter during the past year gone from chronological newsfeeds to “customized” newsfeeds? | Technology | explainlikeimfive | {
"a_id": [
"dt7gs9l",
"dt7lxsk",
"dt7jiay",
"dt7gjds",
"dt7mu8z",
"dt7ljoh",
"dt7obff"
],
"text": [
"[Filter bubbles]( URL_0 ), by encouraging you to engage only with content you already engage with regularly, maximize engagement with their services and thus shareholder value and ad revenue. It also \"sanitizes\" the content, since censoring controversial or offensive content is taken as part of the tailoring, so it's more friendly and non-controversial for advertisers. In other words, by tailoring the content you see to be only naively what's \"relevant\" to you, they create a welcoming and non-challenging content environment where everything is in agreement with you and your personality profile, so you feel rewarded and comfortable in that environment, and thus spend more time in the platforms. This directly rewards them by increasing profit potential. (In my opinion, it's a really messed up thing based on entirely misguided motivations, but our society is based on misguided incentives anyway, so it's not surprising.)",
"One reason is so you don't know when you've reached \"the end\". Used to be I'd scroll through Facebook until I saw the first thing I saw last time and knew there was nothing else. Now I scroll that thing for ages, with no indication I've run out of content.",
"At least in the case of Facebook, it has been much longer than a year that they have had a non-chronological feed.",
"Well, the simple answer is because \"revenue.\" By allowing customization they can then tailor each viewer's ads, which means they can charge more for those ads.",
"The goal of a social media website is to make as much money from people as it can. One of the ways it does that is by keeping people on the site as long as possible. With a simple chronological feed of posts they can’t effectively control what content you see, at any point what you see could get you to leave (or fail to make you stay). The “algorithms” people constantly refer to monitor your time on their site and pay attention to what kinds of post make you like/share, comment, stop scrolling, log out, etc. and will chose what posts to show you to make sure you don’t leave. Now the scary bit is if you’re the type of person who frequently gets into internet arguments then you’re encouraging the algorithm to deliberately show you things that will make you upset (because they know you’ll stick around to comment).",
"A major problem with strictly chronological feeds is that those who post a lot crowd out everyone else. That's especially bad when you have commercial posters who have a strong incentive to maximize their visibility and thus to produce lots of low quality content rather than improving quality.",
"I think an idiom from the world of IT is relevant here: \"If a product is free, you aren't the customer; you **are** the product.\" Facebook exists to package your attention span and sell it to advertisers (as do nearly all free services). They have extensive research that tells them this is the most effective way to monetize your attention. The entire Facebook interface *especially* your timeline is tuned to engaging you emotionally to get you to continue to click on Facebook content, delivering more information to Facebook about your preferences which is sold to advertisers."
],
"score": [
414,
76,
15,
12,
8,
6,
4
],
"text_urls": [
[
"https://en.wikipedia.org/wiki/Filter_bubble"
],
[],
[],
[],
[],
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
7svs8c | What are the reddit bots? How do people go about programming them to do weird, mostly unsuccessful tasks, and why? | Technology | explainlikeimfive | {
"a_id": [
"dt7s3kw"
],
"text": [
"A reddit bot is an automatic computer program that polls reddit for new comments and/or posts and responds accordingly. This is done using [reddit's api]( URL_0 ): just like you can go to URL_1 to get a nice page which shows you the subreddit and the newest posts, the program goes to URL_2 and gets a concise, properly formatted list of the newest posts, which can be easily parsed by the program. Other API functions let the bot access the comments. Using this info, the program can then use the same API to post a comment in one of the posts."
],
"score": [
5
],
"text_urls": [
[
"https://www.reddit.com/dev/api/",
"https://www.reddit.com/r/explainlikeimfive/new",
"https://api.reddit.com/r/explainlikeimfive/new"
]
]
} | [
"url"
] | [
"url"
] |
|
7svxj3 | How do buttons on electronic devices work? | Today I looked at a Playstation Vita handheld console, and I asked myself the question, how do the game respond to the button I press and the joystick (thumbstick) that I use? | Technology | explainlikeimfive | {
"a_id": [
"dt7tbz9"
],
"text": [
"> How do buttons on electronic devices work? A button is simply a switch which defaults to open with something like a spring. Pressing the button completes a circuit and sends a signal to a part of the computer, which in the case of a controller has circuitry inside it which converts the button press into an encoded signal to the console itself. How each program interprets and handles the controller input as reported by the console operating system varies by the game."
],
"score": [
7
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
7swcm3 | Why can't most household internet speeds be a lot faster? | Technology | explainlikeimfive | {
"a_id": [
"dt7wifo"
],
"text": [
"Easy answer the infrastructure isn't there and not very many companies want to pay the money to put it in place."
],
"score": [
3
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
|
7swd4w | With so many different kinds of toothbrush, do they clean your teeth in different ways? | Currently standing in the toothbrush aisle and can’t help but wonder. | Technology | explainlikeimfive | {
"a_id": [
"dt8d0cg",
"dt8oqnz"
],
"text": [
"My dentist said they do not differ in anyway, when taking into account normal brushing habit. You can have the fanciest toothbrush with ultrasonic, self-cleaning, polishing, timer, and tooth map abilities, but yet forget to brush regularly. She said save yourself some money and buy the cheapest generic brand you can find, a 2min timer, and a calendar to mark of the days you brush properly.",
"dentist told me to only use \"soft\" (or if you can find softer) grade tooth brushes. what makes them hard vs soft is the thickness of the bristle and thicker bristles have a harder time getting into smaller crevices."
],
"score": [
9,
5
],
"text_urls": [
[],
[]
]
} | [
"url"
] | [
"url"
] |
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