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73qlca | When deleting data off hard drives to cover your tracks, why do we often see the drives physically destroyed? | I'm talking about in movies and TV shows, like Mr. Robot, when trying to delete evidence or something on a hard drive/usb drive, often simply deleting it isn't enough. I am aware that simply 'deleting' something doesn't necessarily remove it, (it just sets that chunk of data as available to be written over) and forensic data recovery can find it, so I am asking more specifically how can you recover data that has been properly deleted. Like written over, formatted, and wiped clean. Is physically destroying the drives just to be 100000% sure or is there an actual chance that if found the data could be recovered? | Technology | explainlikeimfive | {
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"Think of a hard drive like a notebook. Imagine writing important stuff on that notebook really hard. If you do a simple delete, you're just erasing the cover that says what's in it. Someone can still open it and read what you wrote. You can also overwrite it, which would be like tearing off that top sheet and writing over the dents in the notebook with other data. Even AFTER doing that, someone could still maybe figure out what was written before (just like rubbing it with the side of a pencil). It's messy and you might not be able to make it all out, but maybe enough to be dangerous. Clearly, the more times you repeat writing over that page, the harder that is. Plus it takes forever to cover every inch of that paper. Your solution then? Light the damn thing on fire. Or crush it, break it, physically damage it (it should be noted that just like taping a shredded notebook back together, it is possible to retrieve data from broken drives in some cases, but it's very time consuming, very difficult and because data is written in bits spread all over the drive and not in neat rows as in a notebook, even harder still.",
"Modern forensic technology can recover data even if it was overwritten, even several times. Because if you overwrite a track of data on the medium it does not \"reset\" the original contents to zero. Or, as a simplified example: if a \"1\" is stored as a +1.0 strong impulse, and a \"0\" as a -1.0 strong one, then overwriting an existing \"0\" with a \"1\" might actually give you a +0.9, while overwriting an old \"1\" with a new \"1\" might give you a +1.1. Both read as ~+1 and return as a \"1\", and maybe even the drives electronics does not see them as anything but a +1. Now if you take a high-end specialized measurement device, you might read those patterns with a lot more decimal digits: +1.1 -0.9 -1.1 +0.9 - The harddisks normal electronics would have read \"1001\", but a forensic system might read this as \"1001\" written over a \"1100\". And the more digits they can get (and they have a lot of time to thoroughly analyze each track!), the more \"Generations\" can be recovered. And if they are really determined to read that disk, even denting and shredding does not do the job. It is possible to read the magnetization of each fragment, and puzzle the original contents back together, at least to some extend. Therefor, if you want to get rid of the information you have to heat the drive beyond the Curie point. And that needs some proper equipment.",
"You are getting a lot of either miss-informed, out-dated or just plain wrong answers that go into way too much detail and speculation. Since this is an ELI5 question, I'll do my best to answer: 1. Because it is the fastest, and the safest way to ensure that the data is impossible to retrieve. * 2. Because it is included in some 3-letter agencies' guide to properly dispose of a hard-drive. This should conclude the question part. Now, to address some of the nuances and misconceptions in this thread. * There is a lot of speculation about the possibility of data retrieval after a full HDD \"wipe\". First, we must discuss what could be considered a wipe. a) delete files or quick-format the drive from the operating system b) write 0's on every available memory location. c) write a multiple of patterns on every available memory location, X amount of times (where X is different based on what 3-letter agency guide-book you follow) Now, for a) it is known, demonstrated and widely accepted that this will NOT guarantee the deletion of data. Depending on a multitude of factors, such as operating system, partition type, etc. data CAN be retrieved after this operation. There are a lot of tools that can perform data retrieval in these scenarios, some of them free to use and available for download. b) should be seen, for all intents and purposes as SAFE. There are a lot of old tales, myths and misconceptions about how one can infer the data previously written at a location, and all that mumbo-jumbo. While I will concede that *maybe* this could have been the case decades ago, in a *laboratory environment* with *perfect conditions*, that is very much not the case in any real-world scenario. There is no currently available commercial vendor that will even attempt to recover a 0-filled modern high-density HDD. There are no academic papers published that even hint of this being possible (in fact there are some that have published very much against such claims). It is a myth, it will not happen in real-life, move on. c) is a sort of b) on steroids. If b) could be considered safe, then this will be obviously safer. Alas, the problem with both b) and c) is that it takes a lot of time to completely over-write a HDD, so it stands to reason that a faster method would be preferred when dealing with a lot of hosts. *** Note 1: The above comment does not relate to some edge cases of HDDs that use an on-board firmware (a controller) that deals with bad sector reallocation. There are cases where some sectors could be marked as bad, transparent to the OS, and those sectors might be skipped when over-writing the HDD during a wipe. *** Note 2: The above comment only refers to magnetic HDDs. The subject of data forensics on SSDs is even more convoluted and controversial. Research presented at a recent DefCon conference stated that forensics retrieval of data from SSDs depends widely on a series of factors, such as controller type, OS used (and TRIM support active/not) and so on. Look for it if you are interested.",
"Problem with overwriting 5-6 times which is commercially enough takes time. It could take hours to do that level of writing for an entire drive. Physically destroying the drive takes seconds to minutes and is basically impossible to recover if it's completely destroyed.",
"The ELI5 explanation is that the first part of the hard drive has a list of all the files that are stored on the drive. Many methods of deleting files simply removes the name of the file from the list, but does not actually damage the file itself. So, if someone went in with software, and pulled the data from that address, they could still recover the file. This gets more complex very quickly, with alternate ways to delete files, and technical ways to reverse those deletions, depending on what kind of technology the hard drive uses. But the ELI5 is that - in many cases - \"deleting\" a file from your drive actually just removes its name from the file list, and marks that space as empty, so another file can be written there. It does not delete the actual data, or erase it, or overwrite it in any way. That generally takes special software.",
"Erasing the disk takes **hours**. Punching a hole in the disk is seconds. For disks that are written off, you pick the fast method.",
"Some NSA guidelines for hard drives include c) Disintegration: Disintegrate into particles that are nominally 2 millimeter edge length in size. It is highly recommended to disintegrate hard disk drive storage devices in bulk lots with other storage devices. URL_0",
"The short version: It's quick, snappy, and easy for the typical viewer to understand. You didn't just delete something, you've outright destroyed it. It's a great visual cue to say \"you're not getting what you wanted\". The slightly longer version: It's often a better way to make data more difficult to recover, and requires little effort on your part. As you pointed out, deleting something doesn't make it inaccessible - even after several wipes, if you spend enough time, you can reconstruct almost *anything*. But if a drive has been physically damaged, it becomes far more difficult to read the data to begin with. Not impossible, but definitely far more time-consuming and costly. There are data recovery services that can, under the right conditions, recover data from even fire-damaged drives. So long as the platter is more or less in one piece, there's a chance that with enough time, you can try to reconstruct it. But these services aren't cheap by any means, and are basically out of reach of all but government agencies or large corporations that *need* whatever data is on those drives.",
"It all depends on exactly how sensitive your data is. If only a short text could be enough to cause problems, you really should physically destroy it. If it's more a matter of the totality of the data, then software methods are sufficient. Either way, I find it simpler to just take the drive, but it into my drill press and drill a few 20 mm holes straight through it. No one will ever recover any information from it after that, not matter what. Easier, faster and safer.",
"Because just deleting them may not be good enough. Unusually when you delete a file of your computer, you don't actually delete it. The process is more like striking out an entry in an index in a book but laving the pages the entry pointed to where they are. The data is still there, just no as easily accessible. There are programs that can find and restore files which have been deleted that way. so when you really want to delete something you don't just tell the computer to delete the file, you make it overwrite the actual data with something else. That is usually sufficient. However the way a harddrive works on paper can be quite different than the way it works in practice and it turns out that instead of having just 1s and 0s there are really a number of different stetes and that for example a one overwritten by a zero will look differently than a zero overwritten by zero. Somebody using specialized technology to look at the physical disks might be able to tell the difference. The solution to that is usually to overwrite the entire disk several time with different patterns to make such an attempt to read what was written too hard. That should be enough. Physically destroying the drive at this point does not really bring any extra benefits, but sometimes people are just paranoid and the tiny risk that somebody might still find something on them is still seen as too much. On the other hand there is the problem that wiping drives like that is something that takes time and resources and that it might be cheaper to simply physically shred drives instead of wiping them not in addition to wiping them. There is also the aspect the physically destroying a drive is a very visual thing. It is something you can show to clients and bosses and the public to show them how much you care about security, it provides a much better PR opportunity than simply showing them how you boot DBAN via PXE and let it run for a few hours.",
"To add to all the other explanations, you do not need to wipe a drive multiple times to securely erase it. I’m on mobile so it’s hard to get sources but there has been lots of evidence that more wipes did not erase information any more securely than just a single pass with zeros. To be fair, there has been a study involving some magnet reading machine that tried to read back the data after being wiped seven times, but it was a research case and it never went commercial because of the cost, and also because it wasn’t very credible. (Never mentioned if the data read back was intact or even if it was able to be read back.) Movies often use gross oversimplification, because it’s easier to explain to the non-technical people and it’s faster to move along in the plot."
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73qywf | How did my new HP printer connected itself to my wifi network without me giving it its name and password? | My new HP printer (deskjet 3630) connected itself to my Wifi network. I just installed the HP software on my computer, it searched for printers and found the 3630 and connected it to my computer. I never had to specify which SSID to use or the password. The 3630 has its own SSID, so I can understand how the software found the printer, but I don't get how it connected to the right network. Did the software found the SSID AND the password to it on my computer? I can see the 3630 has a DHCP lease on my wifi router. Thanks in advance for any explanation. | Technology | explainlikeimfive | {
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"The printer uses something called [HP Auto Wireless Connect]( URL_0 ). When you install the software on your computer, it obtains your current wireless configuration from Windows and sends it to the printer via its own wireless network. (This may temporarily disconnect you from your own network).",
"Many wireless routers support something called WPS, or wireless pushbutton setup. Newer printers are actively looking for devices to connect to for either computers or mobile devices. If your printer software is installed on a computer with wireless access it can trigger this setup mode which then engages the \"credential-less\" setup."
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73qzxl | when you cancel a download where does the data already downloaded go ? | Technology | explainlikeimfive | {
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"The space allocated for the entire program, it just becomes unmarked and available for rewriting."
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73rr4z | Why do we need IP address to be connected to internet? Don't we have MAC address already? | I know my question is pretty basic, but what I don't get is **why do we need both addresses to locate a single computer?** In real world, we always have one address, right? So c**ouldn't internet be possible using only MAC address?** MAC addresses are already too many, so there would be no problem like IP address deletion. So, **why do we need another separate addressing system in addition to MAC address? or to be precise, where do MAC address fall short of?** Thanks. | Technology | explainlikeimfive | {
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"The MAC address is just an identifier for your computer (well, your network device, to be exact), but it can't be used to locate it. If I take my computer and fly halfway around the world, I'll still have the same MAC address but I'll be in an entirely different location, so how would packets know where to find me? IP addresses however are dynamic and structured. They are assigned by whatever network I am currently connected to and determine where I am, so that routers will know where to deliver packets that are addressed to my specific IP address. For example if my IP address starts with '9' then the routers will know to deliver the packets to IBM's routers (who own the 9.0.0.0 IP block). IBM's routers will look into the rest of the IP address and decide how to route the packet internally. For an analogy, a MAC address is like your name, while an IP address is your home address.",
"There are (at least) two problems with MAC addresses: First, they're not always unique. Second, they're not routable. IP addresses are structured hierarchically, so that if I'm a router on the internet, when data to a given IP passes through me I don't need to know that specific IP address. I can look at the first part of the address to determine roughly where in the world it should be sent. If it has this prefix, it goes to Germany, but that prefix and it goes to Brazil. (It's a bit more complicated than that, but that's the basic principle). I don't need to hold a table of all 4 billion IP addresses and remember for each and every one where in the world it is. They're grouped together so all addresses in *this* range go to this ISP in that country. Once the packet reaches that ISP, they know which of their customers it should be sent to. So each router only needs to hold a relatively small amount of routing information, in order to be able to route *any* packet to *any* IP. MAC addresses have no such structure. Any given MAC address could appear anywhere on the planet at any time. So to route data based on MAC addresses, every single router on the internet would need to know the location of every single MAC address on the internet, in order to know where to send packets destined for any particular MAC address.",
"MAC addresses aren't used for every networking protocol. In particular, PPP doesn't use MAC addresses or, in general, any other identifier for nodes. The Internet is explicitly designed to be a bridge between different kinds of networks and technologies, so it can't rely on the details of any lower-level networking protocol."
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73sti6 | Why do some applications hide, often rudimentary, settings behind an 'Advanced' section. | Google Chrome does this for example. | Technology | explainlikeimfive | {
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"So technologically-inept people (e.g. your grandma) won't accidentally mess with them and then call you in a panic: \"I've deleted the internet!\"",
"One key element of effective interface design is restricting the number of immediately visible options to only those elements most likely to be used by a novice. If you've only got 5 options to choose from, it's normally pretty easy to tell which you should use. Similarly, it's pretty easy to figure out what all 5 of those options do (and whether you need a different option than is available) in short order. In contrast, when you've got hundreds of options to choose from, you don't even know where to start and you can very easily get frustrated."
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73sv7k | Why do TV series' from cable/streaming services like HBO, Netflix or Hulu seem to be so much higher quality than network TV? | Technology | explainlikeimfive | {
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"Because of advertisers. Since on subscription services most of their revenue comes straight from the consumer they are willing to create more diverse content. So they might not have as many viewers but they're getting more money from less viewers. On network TV the advertisers want to be seen by as many people as possible so the producers are forced to put on shows that appeal to the most audience, your lowest common denominator. Also advertisers don't want their products associated to shows that may be offensive to someone. Same thing is happening on YouTube, advertisers are getting more restrictive on what they want their products being associated with so any thought provoking video will be demonetized. And all its left is rich kid vlogs, makeup tutorials, tech reviewers, click bait, top ten anything's, and grown ass men screaming into a microphone while playing a child's videogame.",
"They are not of higher quality than network TV, but it have two advantage that network tv doesn't have. 1) Streaming services are on demand so people can watch what they like. A network tv don't try to put bad show on, they try to put show that most people will like, but people have different taste. So you may like the show that air on Tuesday and dislike the show on Monday, but your friend like the show on Monday. The show on Monday isn't a bad show, it is just not of your taste. So if you look at the total schedule of a network TV you may like only 2 show, but that doesn't mean that only 2 shows are good. Additionally, sometime a show is really just bad, but they didn't know that before it air and people started to talk about how bad the show is. So the network finish the season and don't renew it or can even cancel the show mid season if it's really bad. With streaming services again, you only watch show you like. But look at all the shows on netflix. What percentage of all the shows do you like? Personally, there is a lot of stuff that I don't like on netflix, but every time I want to watch something, I watch something I like. 2) Network TV have a limited amount of time on the air. They can only air one show per time slot. So they have a limited amount of show they can have. There is no such limit on streaming so they can pick up a LOT of shows if they want. Additionally, a network tv need to fill 24h a day (for most), so they won't want to spend too much money on show that air at 2am or 1pm on Monday when very few people are watching. Again, streaming doesn't have that problem, they can make or pay for show that target the big audience because that audience can watch the show when they want."
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73vzag | Why aren’t we accessing Dark Fiber? | Technology | explainlikeimfive | {
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"The dark (unused or underused) fibers in question usually run between telecom hubs, such as phone company office locations. The big problem in telecom infrastructure is the \"last mile\" -- connecting thousands of buildings to a local telecom hub is expensive. In fact it can cost more than all the long-distance fibers.",
"A lot of times dark fiber is just a back up route and not intended for traffic unless there is a problem elsewhere."
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73w2ro | Why was there such a debate between Edison's DC and Tesla's AC? | I have seen so many quarrels over the years, and still we use both, but one was there such a debate and why can't we decide on one? | Technology | explainlikeimfive | {
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"you seem a bit confused. We do not use direct current for power transmission over distance, which was the focus of the war of the currents. There is too much loss due to resistance, too much risk of fire, and too much risk of electrocution. Edison was heavily invested in DC. Setting up local power generation stations, a necessity for DC transmission, would have been very very expensive....which equals very very profitable for edison. Teslas AC technology allowed for longer distance transmission of power with lower losses and less risk of fire/loss of life....which is why Alternating current won the battle and is what we plug into today.",
"Because they have different strengths and weaknesses. Volt for volt, AC has less power loss than DC over long distance. Amp for amp, the cost of stepping up and down the voltage is much easier. Higher voltage loses less power than low voltage. DC is useful because it drives semiconductors which is the basis of all computing technology. Computers don't run on AC So as long as you are transmitting power over distance, you always have to have both."
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73wmqm | Why does single-serve water typically come in plastic bottles, single-serve soda typically come in aluminum cans, and single-serve beer come in either aluminum cans or glass bottles? | Technology | explainlikeimfive | {
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"Beer comes in glass bottles or cans because certain wavelengths of light can damage ingredients in the beer and make it taste bad, and plastic doesn't block those wavelengths like aluminum and glass. Aluminum cans could be used for water, but a bit of the aluminum does dissolve into the drink. Sodas typically have enough other flavorants that you don't notice the aluminum taste, but it would make plain water taste unpleasantly metallic. You'll notice that soda often gets stored in plastic bottles as well. Glass is more expensive than either, however, so you see that least often.",
"Before I go on, there are a few little things that make a big difference. Plastic is the cheapest. Glass is the most expensive. Cans are effective and still relatively cheap, and flavor issues aren't much of a concern as there's a small coating of plastic inside the can. Cans and glass bottles can also hold carbonation much more easily, hence why they're more likely to be the choice for beer and pop. Beer: cans and glass bottles don't 'leak' oxygen through the walls, which spoils the beer. Bottles are usually heavily tinted and cans block all light which helps keep it from degrading, as some wavelengths of light break down flavors in the beer and make it taste pretty gross. Pop: Cans, glass, and plastic. almost anything goes because they are sterile already and don't have to worry about the flavors spoiling like beer. Cans are relatively compact and fairly durable, but more expensive than plastic bottles, and glass bottles can help preserve the taste more, since cans have a thin plastic coating on the inside to prevent the aluminum from altering the taste. Glass bottles are the most expensive and most people don't notice or don't care enough to spend twice as much on a bottle of pop. Water: Water, well, water. It doesn't have the flavors to worry about, so the cheapest option is chosen: plastic bottles. By using only one kind of bottle they can also further reduce the cost because the economies of scale are a beautiful thing.",
"The container cost is the majority of the cost of bottled water. Plastic resin as thin as possible is the cheapest container for water. Carbonated soda typically is also sold in a plastic container, albeit thicker to withstand the pressure of carbonation. Some drinks, (Gatorade, Powerade) have fermentable sugars and have to be \"hot-filled\" to kill the bacteria that would allow fermentation to continue in the bottle. Those containers have to be even more substantial to withstand the heat of the product. Beer could potentially be sold in plastic in an enclosed cardboard carton to eliminate light spoilage (they sell clear glass-bottled Corona and Miller Hi-Life) But from a marketing perspective, nobody wants their beer in plastic, so it's glass or aluminum",
"Carbon dioxide diffuses (escapes) through plastic faster than through metal, which is why it is preferred to store carbonated drinks in metal rather than plastic (this extends their shelf life before they go flat). This is not a concern for water, so plastic is chosen because it's cheaper.",
"Water is not photo sensitive nor is it pressurized. Cans are cheaper than glass and easier to recycle but beer (or soda) tastes better in glass. Plastic though is cheapest of them all.",
"Can I ask a follow up question? Does that mean the budweiser water passed out at emergencies tastes metallic?"
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73wzio | Why does it always feels like gaming graphics can't get any better? | Technology | explainlikeimfive | {
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"Because you can’t imagine what they would look like if they could be better, until you see them being better. Then you can’t imagine them being better than *that* and so on",
"They do make games with perfect graphics. But it's a lot cheaper to use a stylized style. The most impressive game graphics occur in movies and you *can not* tell the difference between a CGI tentacle-waving monster and one made of real things. (pirates of the Caribbean) But that's expensive. Too expensive for a game that needs 100X the objects and animations to cover every situation versus a movie that needs 5-20 second clips here and there. So they either try to make it 'life-like' and fall short due to budget or they go with an entierly different style. Computer games have been able to serve up photorealistic graphics for about 5 years, but no one does it because it costs too much money. -edit- for an example of this watch this Youtube clip then read the spoiler tag, that UFO looks really realistic - URL_0 OK I give up on making a spoiler tag work, here it is -\"And so does everything else, but the entire car, the human, and the scenery are all CGI and not one bit of it is real\"",
"I was thinking about this - until you can look at a game and honestly not know if it's real life or not, they can get better.",
"Omg, I remember when they started advertising for the GameCube I thought it was the biggest scam. I distinctly remember arguing that the graphics couldn't possibly get any better- it was already 3D, what could they improve upon? Lol so dumb.",
"It's silly to think that gaming graphics can't get any better. Up until you're unable to differentiate between a 3d screen, and the real world, there's improvements to be made.",
"I remember seeing the octagon circles in Mario64 for the first time and thinking their circles looked pretty funny, or the tree sprites which looked the same at any angle. Bare in mind that toy Story was released at around the same time, so even in 1996/97 it was obvious that there were differences in games vs movies and that there room to improve. The big thing about Mario64 was the fact that you could control Mario in more than two dimensions, likewise Metal Gear Solid had questionable graphics, but the scale of the story, audio quality and awesome gameplay made up for it.",
"As a non gamer looking at the graphics of the games that my husband plays: why do I always think \"it still looks horrible, they should be able by now to make it as perfect as animated movies\" hahaha, sorry, no answer but different point of view. So maybe it has something to do with being used to it?",
"Say hello to the **Unreal Engine 4**. God I can't wait to see developers utilize that glorious beast. Take a look (music stops after the intro): URL_0 It blows my mind to think of playing video games with these graphics in virtual reality. In 10 years time we will be able to take a realistic trip to Bora Bora while our cars drive us to work.",
"Because those people have limited mindsets and can't figure out ways to improve things. Like before uber, who thought the taxi industry even needed an overhaul. Before amazon, who wanted to buy books online. Etc etc.",
"Let's say that you've got a character that you want to represent. In the old days, it might be a straight up 2 dimensional square on a background. Eventually, graphics evolved to tiny pixelated designs called sprites, like the original [mario]( URL_2 ), who is just many 2D squares on a background. Sprites only got us so far, because then we got to 3D models like in the N64. This is where we get into the idea of a modeling concept called [polycount]( URL_0 ). Essentially, to 3D model something, a computer uses a number of triangles to make shapes. Obviously making something round is very difficult with triangles, so early 3D models had relatively sharp and blocky designs. This is why [Lara Croft]( URL_3 ) in the original tomb raider has triangular tits, and why [fox on the original N64 smashbros]( URL_1 ) looks so blocky compared to the gamecube version which came out only a few years later. The only difference in these 3D model comparisons is poly count and texture quality. To my knowledge, they are both rendered the same way by a computer, the new models are just made up of hundreds of thousands more triangles. That said, once you get to super high polycounts in our current generation of gaming systems, you start to see diminishing returns. At some point, what we see is \"good enough\" and doubling the polycount of something to get even smoother and more exact edges is no longer worth the money spent to produce it. At this point, I think our 3D models really don't have a lot of room to get better, at least not anywhere close to the jump we saw from N64 to GameCube. Xbox 360 to Xbox One has a much less significant gap for example. I think the next big thing for video game graphics won't be textures and models, but optimizing for frame rate so that motion within the game is as smooth as possible."
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747qjb | why are unmanned planes/helicopters named after male bees? | Technology | explainlikeimfive | {
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"In the 1930s there was a kind of British plane called the [de Havilland Tiger Moth]( URL_0 ). They made version that was a remote controlled plane to practice shooting at it. They called this the Queen Bee. The Americans saw this was nice, so as a play on words, when they started making their own remote controlled planes they called them Drones in reference to the Queen Bee",
"At the risk of being pedantic, there is a clear distinction between \"drones\" and \"unmanned aerial vehicles.\" An unmanned aerial vehicle or UAV is a remote piloted aircraft with a human controller. They're still called \"drones\" by the media and in non-military circles, but that's technically incorrect. Drones are piloted by a computer program. < /pedant > To answer your question, a drone has nothing alive on board. It's flown by radio, and the name \"drone\" comes from the fact that it's mindless. We also refer to listless and unimaginative human workers as \"drones\". A drone in a bee hive doesn't seem to have much of a mind of its own either. Drone = mindless/mechanical/robotic/not human."
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749f4m | Why do PCs make a beeping sound whenever you press 3 or more keys down? | Technology | explainlikeimfive | {
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"> Why do PCs make a beeping sound whenever you press 3 or more keys down? A standard keyboard saves cost by not having individual wires connected to every key but instead conveying a key press as a combination of several signals. To picture how this can work imagine a grid of wires 5 to a side. Now with sampling only ten wires you can detect which of 25 possible intersections are being triggered. The particular way in which those simple keyboards are set up is such that pressing three or more keys cannot be distinguished into the specific keys being pressed; there is ambiguity in what is happening and the computer sounds the beep to warn the user that their input isn't acceptable. Gaming keyboards are set up to prevent this event and many can handle any number of simultaneous key presses which would avoid the beeping.",
"Also I've always wanted to know does it have its own speaker for the beeping? It doesn't come out of my main speakers."
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74alwt | Why do electronics which have gotten wet, stop working even when they completely dry? | Technology | explainlikeimfive | {
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"In addition to the damage being done on contact (i.e. creating short circuits leading to immediate or near-immediate failure); tap water, rain/flood water, etc contain a lot of impurities. The evaporated water leaves these behind which may create a delayed onset of corrosion, which can cause poor contact between components and connectors. Distilled water is actually safe for most printed circuit boards (at least those with sealed components) as long as it is applied and completely dried before power is given to the device.",
"Water conducts electricity, so if a device gets wet, it can short out and destroy some components. It's like wiring every component to every other component. Bad news. Only one component in an important pathway has to die for the device to stop working."
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74bbl5 | Why do websites require complex passwords when anyone trying to brute-force guess your password would get locked out after a few failed attempts? | Technology | explainlikeimfive | {
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"You usually dont brute force the website. You use a security hole to steal the hash database and bruteforce that. There you have as many attemepts as you like.",
"Because early data breeches have shown that when passwords aren't complex people all tend to use the same few passwords. All a hacker has to do is try the top few passwords on all of the accounts until they get locked out and have access to the majority of the accounts. Password complexity is an attempt at forcing you to be unique.",
"In the old days, when you created a user account you would ask the user to choose a username and a password. You'd simply store those two things, and whenever the user wanted to log in you'd just look up the username in your database, compare the password they entered to the one set for that username, and let that user log in if the password matched. There were two problems with this. The first one is that anyone who had access to your database could simply look up user passwords, and log in as those users. You'd have no way of knowing. The other problem is, someone could gain unauthorized access to your system and obtain the entire database of usernames and passwords, and then they'd know exactly what to type in to login as anyone. Okay, so that's no good. What to do? Someone had an idea—when a user creates an account, let's not store the password. Instead, let's encrypt the password using a particular technique called a *one-way hashing function*. Sounds complicated, but it's really not. All it means is that you jumble up the password the user entered in such a way that you can't undo it to get back to the original password. For example, let's think about numbers for a minute. If you give me a method of \"encryption\" where, say, you take my number and multiply by 3 and add 5, if I choose a number like 15, then you store 50 (3\\*15 + 5). The problem with this method is that if someone gets the database and sees 50 next to my name, they'd type that in and it would fail. But, since they have access to my system, they can go through it and see what method I use. Once they know that, they can simply subtract 5 then divide by 3 to undo the operation, then log in with 15. This is *not* a one-way hashing function. Instead, what you could do if you're clever, though, is encourage me to choose some big number, and then divide it by something, and take the remainder. Look how this works: if I choose, say 13,456,994 as my number, and you divide by 145, you get 92,806 remainder 124. You store only the 124, though. Next time I log in, as long as the number I put in gives a remainder of 124 when divided by 145, you let me in. The bad guy doesn't know what I'm putting in, though. Ah, but they could figure out that all they have to do is put in some number that gives the same remainder when divided by 145—good point. So you also keep the average of the digits in addition to the remainder rounded down to the nearest whole number. Now the database stores a remainder of 124 and 5 as the average of the digits. Well this makes the problem a little harder for you to find a number that has a remainder of 124 as well as 5 as an average of the digits, but you could probably do it. But you see the point by now, right? So, a one-way hashing function is a function that produces an answer which can only be reversed into a particular input with a LOT of work. It's actually less work to just try to guess passwords, put them through the one-way hashing function, and see if they match. You could easily create an entire dictionary of common passwords based on the one-way hashing function I use, then just compare those to all of the encrypted values I've stored—you'll probably get a lot of matches, and each one is an account you can log in to. This is why sites force people to use special characters. The hope is that you'll be forced to take some kind of password you would have normally chosen that's in the bad guy's encrypted dictionary and modify it in such a way that it isn't in there. (Unfortunately, this is no longer a good approach. All of the modifications people typically make are now in the bad guy dictionary. For instance, if you would have used `password` as your password, but there's rules, you might instead choose `pa$$w0rd`. The bad guys know this, though, so they simply add more entries to their dictionary to include all these variants as well, the encrypted versions of: `passw0rd`, `pa$sword`, `pa$$word`, and so on.)",
"There's a couple reasons. First, let's consider someone thinking, \"well, SOME idiot is going to type \"password\" and submitting that as a password for every account on a site. No account gets locked out, since each only got one bad attempt. Second, consider data breaches. You might have a hashed and salted list get leaked, but if 14 people have the same salted hash, you know that's a weak password. You can then compare that to passwords/usernames in other breaches that leaked raw passwords, and you have a good guess on those accounts. It used to be a recommended best practice as well, and not a lot of sites have updated their policies since it changed. Currently best practice is to remove all password rules and compare chosen passwords against a bad password list."
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74f7sk | What is a DDoS? | Technology | explainlikeimfive | {
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"Imagine a call center. It has a lot of phones to help ordinary customers. Most of the time only a portion of available phones are being used so everyone who calls in will likely be served. Now imagine you really dislike this call center, maybe you had horrible service once, maybe you are just a mean person. irregardless, you want to take down this call center. What you do is you get a thousand phones or a bunch of your friends that each have a few hundred phones to start calling the phone center. The phone center answers, and the caller doesn't really say anything, just keeps the employee in the center busy. While the employee is talking to you, he can't talk to actual legit customers. Have enough phones distracted doing nothing at once, and soon the call center won't be able to do what it is actually supposed to do: help people who actually have problems with their IT or what you have it. With every single phone operator busy trying to talk to your evil phones real customers are left to starve, and the phone center stops working. We've gone from everyone is getting served at this phone center, to nobody getting served. That's the basics of a DoS. You have a webserver somewhere being bombarded with so many fake requests that it can't respond to actual, legitimate requests, meaning the website or service the webserver is supposed to be providing comes crashing down and stops working. This causes immense financial damage to the company in question since it relies on that server being up and running constantly.",
"DoS mean Denial of Service. This a kind of Attack that have only one aim : consume all ressource a server can allocate to answer customer requests, by consuming thoses ressources you prevent the legit customer to access the service, enhance the name : denial of service. Typically the first DoS was working on network protocol level. When you open your browser and go to a web page, you send several request to the server, establishing a discussion between you and the server. A server have a limited number of ressource, so he can answer to a fixed number of customers (browsers). By sending a carefully crafted request, you basically use a ressource, preventing the server to use it for a legit customer. By sending a lot of request, you claim a lot of ressources from the server to answer your requests. In order for this to be effective, having only one computer setup to attack a server, mean that mostly you'll have less ressources in final (network bandwidth, open sessions,...) than the server you are attacking. So it is a form of DoS as you prevent some legit requests to be answered by the server, but this one is still able to somehow process a part of legit request. So to have a really effective DoS, you need to attack a server with several computers. Basically, you distribute the attack processus between several machines, that will attack the same server using the same method at the same time. This is called Distributed Denial of Service. The more computer you have to attack a service, the better is. As you can then rely on basic attacks instead of going on more complex ones. Currently, we see a move of the kind of DDoS from network DoS to application DoS. Before, you where trying to echaust network ressources, now it is more effective to exhaust backend ressources, such as the backend database, by asking the service to process heavy requests that take a long time to compute."
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74f8k4 | When connecting to a public Wi-Fi hotspot, why is it often necessary to try to go to an http://, and not an https://, webpage to get the sign-in screen to show up? | Often, when I attempt to access public Wi-Fi hotspots - in places such as coffee shop chains - that feature sign-in pages or require the user to click "I Agree" or "OK" to begin using the Wi-Fi, the sign-in page will not be triggered until I have typed in and attempted to visit an unsecured (http://) webpage. If I try to go to Reddit, Google, or any other page that uses an https:// protocol, the loading icon will simply rotate forever or until the request times out. Why can the sign-ins be triggered only by an http:// page? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"The sign up page works by directing your request for http:// URL_0 / to a server controlled by the wi fi provider. That server then responds pretending to be URL_0 , telling your browser to go to URL_2 instead. That works fine for HTTP, but with HTTPS the server has to provide a certificate proving that it's really URL_0 . Since the server doesn't have that certificate, your browser would know that it's talking to the wrong server and trigger scary security alerts instead of loading the sign up page.",
"The whole WiFi login screen is a hack whereby the WiFi service pretends to be any website you're visiting so it can present its login screen, even though you didn't try to visit the login screen. HTTPS requires a cryptographically signed certificate to prove that the site you're visiting is the site you think it is and, of course, the WiFi service doesn't have such a certificate. That's a major feature of HTTPS: stopping man-in-the-middle attacks. What the Wi-Fi service is doing is exactly a man-in-the-middle attack.",
"Usually the browser does a few extra check with https request, like being sure that you go on the page where you expect to go. If there is a login page the browser will raise an error thinking that the security is compromised (somehow it is since you don't go where you expect to)"
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74g43g | Would a fully 1 to 1 life-like virtual reality ever be possible? | Technology | explainlikeimfive | {
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"text": [
"Hypothetically, yes. Assuming we have no limitations on processing power, it's already quite common for graphics to be realistic enough (just check any trailer for a First Person Shooter to see what I mean). Projecting this in a fully 3d space is hard, but let's stick to the unlimited processing. The next step is AI (to simulate realistic animals and people). This AI doesn't need free will, it just needs to look like it, which can probably be done with enough time. Physical response would also be important for a life-like simulation. You'd probably need a rig that could constantly adjust itself to where ever you are in the simulation, which is probably where a limit is reached. It's just to complicated to create the proper physical touch in as short an amount of time you'd need. However... if you're willing to get some rather invasive surgery, you might be able to get electrodes that would send the signals your brain would receive from touching something artificially. So, to answer the question, if we get powerful enough processors and improve neurology, yes. Just don't expect it tommorow. EDIT: Grammar, Typos, and Clarification"
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74gfe5 | What prevents video game developers that have digital content get sold by third parties from creating the content themselves and selling it? | Technology | explainlikeimfive | {
"a_id": [
"dnz5iaa"
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"text": [
"If you mean officially, why would they conceal it? They could simply sell any skins they wanted through an official store. IF you mean an individual developer, that would be at minimum a breach of their employment contract at at worse a fraud charge."
],
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74hqg8 | Whats the difference/distinction between semi-automatic and automatic weaponry and what are/how do Bump Stocks turn Semi-Autos into Automatic weapons? | Technology | explainlikeimfive | {
"a_id": [
"dnyd9oj"
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"text": [
"A semi-automatic firearm fires one bullet each time the trigger is pulled. To fire a second shot the trigger has to be released and pulled again. An automatic will keep firing as long as the trigger is pulled and isn't released. Bump Stocks don't turn semi-auto's into auto's they just cause the trigger to be pulled extremely quickly by 'bumping' the weapon forward so the trigger is pushed into the finger which has the same result as if the finger was moved back to pull the trigger. Bump Stocks enable the trigger to be pulled much faster than if the operator actually was actually moving their finger each time."
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74i7un | Why is it necessary for generator engine size to increase as output voltage increases? Is it possible to run a 50Kw generator with a tiny 1000cc engine? | Technology | explainlikeimfive | {
"a_id": [
"dnyhjq2",
"dnymvqo"
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"text": [
"Voltage has nothing to do with generator size, power does It is totally possible to run a 50 kW generator off a 1000 cc engine, 50 kW is only 67 HP. It's a very different story if you want a 50 MW generator, that'd be 67,000 HP so you're going to need a really big and powerful engine",
"The generator can only output as much power as the engine outputs -- otherwise you'd be making energy from nothing, which would be magic. One horsepower is just an old-fashioned term for 746 Watts, so if you have a 10 hp engine, that engine can produce up to 7460 Watts of energy, and can never run a generator to produce any more than that amount."
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74imvb | How do online games run? | When you install a video game on your PC or Console, the sounds, textures, models, etc. are saved to the hard drive and the game loads them up when you run it. How do flash games and things like that run? Does it need files? | Technology | explainlikeimfive | {
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"text": [
"Your computer cannot show you anything from the internet without downloading what it wants to show you from it first. Online games run like every other game. The game logic and all accompanying assets such as sounds, models, textures, sprites, whatnot, are downloaded and executed from your computer. Then the computer runs them as part of the website. Some games are smarter than others and only request the files it needs to be downloaded as it needs them. Instead of downloading all 50 levels it only downloads level 1. Then you finish level 1 and it goes off to the website and asks for the files it needs for level 2, and then 3, and so on. Flash games are much, much smaller than the games you normally play via Steam for instance exactly because they are intended to be played online. Flash games are a few mb large at the most. \"normal\" games are on average several hundred Mb, most a few Gb. Having a flash game be a gigabyte large would be a disaster, nobody would be willing to play something that drain their bandwidth and take several minutes to load on a sub optimal connection."
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74jbq9 | Why is it so difficult to stop spam phone calls? | Technology | explainlikeimfive | {
"a_id": [
"dnyqzhc"
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"text": [
"Because (mostly) they come from countries where they don't have to follow your laws. So they don't, and there's nothing you can do about it."
],
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74kfp8 | why can modern wall adapters be plugged in either way? | most wall outlet plugs only fit one way here in the US due to one being wider than the other, however all of my USB to wall adapters are reversible. when did this happen and how does it work? | Technology | explainlikeimfive | {
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"dnz0cpn"
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"text": [
"UL rules are if you can prove neither prong can accidently electrify anything outside the charger you don't need a polarized plug (a plug that fits one way). Generally that would be devices with an entirely plastic case (so a lose wire can't electrify anything) and full isolation between the wall and the power (basically, prove that the USB side isn't connected to either of the prongs with a conductive path). If you can't do that, you need polarized plugs (which are used because only the \"hot\" wire is suppose to have voltage, so the neutral should be safe to touch), a polarized plug makes sure it's in the right direction. Practically everything is designed to not need a polarized plug because it's safer. Things that need a polarized plugs (like stuff with a metal case, or an air conditioner, etc) generally require a three prong plug (because neutral is only suppose to be safe to touch, ground actually is considered safe to touch, and ground is suppose to be connected to things you touch)"
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74l1qd | What is the advantage of having "custom silicon" on your hardware products (like that popular smartphone does)? | Technology | explainlikeimfive | {
"a_id": [
"dnzcweu"
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"text": [
"Custom silicon is smaller, better, and more power efficient than building electronics out of more generic building blocks. Just like injection molded plastic is superior to building your product out of LEGO. The only reason we don't build everything out of custom silicon is that there is a huge up front cost (called \"NRE\"). So the first custom chip costs $250,000.15. The rest cost $0.15."
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74l25n | Does Moore's law protect us from the singularity? I understand both a little, but not enough to know the answer. | Technology | explainlikeimfive | {
"a_id": [
"dnz7fw1",
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"text": [
"Moore's law is hardly a \"law\". He essentially saw a historical trend for the number of transistors on a processor and made a statement about what he thought was going to happen in the future. Generally speaking though, it's not a sound argument to extrapolate from historical data because you're moving out of the space that you obtained your data from. The guy himself said that his law was going to die in the next few years. URL_0",
"not sure what connection there would be, but moore's law was pretty much a gimmick, it was a self fulfilling prophecy, and it hasn't held true for the past few generations."
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"https://spectrum.ieee.org/computing/hardware/gordon-moore-the-man-whose-name-means-progress"
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|
74m14p | how do telescopic sight or scope in sniper rifle work? The scope is few inches higher than the bullet line so how are the bullet hit the mark in the scope? | Just like the title. And super sorry for my english. my Third language | Technology | explainlikeimfive | {
"a_id": [
"dnzdj4u"
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"text": [
"[Here is a helpful diagram]( URL_0 ), that shows an exaggerated view of what's going on. Bullets don't travel in a straight line, despite what it might look like. They travel up and then down in an arc, called a ballistic arc or path, just like throwing a football. Light on the other hand, for all intents and purposes, does travel in a straight line, which brings about your question. To make sure your bullet hits what you see through the scope you \"zero\" or \"sight in\" the scope or optic. This is where you pick a certain range, say 25m, where the bullet will be passing through that point where it looks like it is in the scope. It will then again pass through another point that is in line with the scope on its way down, say 300m. A shooter can pick different ranges to zero his scope, and each one will have a point where it intersects with the straight line path of the sight or scope on its way up the arc, and again on the way down. Different bullets, different barrel lengths, different calibers, etc all change what these paths are, so a good shooter will make a table or chart for a specific rifle, scope, bullet weight, amount of gunpowder, etc and calculate where the bullet will be for that particular setup at any given range."
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74mprl | If font 'points' are a fixed size (1/72"), why does one font at 10 pt (e.g. Calibri) look appreciably smaller than another (e.g. Verdana) at the same point size? | [This is what I mean]( URL_0 ). | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"The point size is the overall height of the space where the letters are drawn. The letters don't actually need to completely fill that height (some letters can be shorter than others and they might not even fill the space). [This is what I mean]( URL_0 ) Honestly the more annoying thing is that different fonts can have different baselines - the distance between the 'top' of the letter box and where the letter 'sits' on an invisible line. This means that if you take writing in 2 different fonts you potentially have to expand the height of the line so that they both share the same baseline position. So if you've been laying out a line of text in one font and want to use another you might have to lower the line you just made because the new font has a lower baseline despite being the same overall point size. If you don't the new font might overlap with letters from the line above.",
"Originally the point size of a font specified the height of the metal pieces on which the letter shapes were cast. That meant the total height of the letters was more or less physically constrained to fit within this dimension. But there's no rule that says fonts can't be shorter than that. (At least in the old Calson and Garamond fonts the italic faces are noticeably shorter than the roman.) With digital fonts there's no reason letters can't be taller that the font size either. There's no set-in-stone standard about how to measure the point size of a font. There's so much variability in font design that it would be very difficult to come up with a standard that matched human perception of the comparative sizes of fonts. Also, points are a fixed size now in digital typography, thanks to Adobe. There have been many other slightly different standards over the years.",
"The size being specified is the vertical height of the letters. What you're noticing is that some fonts have thinner characters and some have wider ones. Verdana has wider characters than Calibri does (particularly notable in letters like capital T, lowercase H, and lowercase P), so it takes up more horizontal space at the same point size."
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74n5co | Why can’t/don’t ATMs give you money in denominations smaller than $20 these days? | Technology | explainlikeimfive | {
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"It's how they are setup . Every ATM has canisters in them filled with cash and only so much can fit in them so the people who own the ATMs decide to put only 20s in there so they can fit more money in there. The ATM at my old job had one that only gave 20s and 1s for the vending machines. It's also easier for independent ATM owner just to fill it with only 1 denomination.",
"There's a PNC Bank by my house and the attached outdoor ATM dispenses anything from $1 bills - $20 bills.",
"Back in the '90s a handful of ATMs also used to dispense $10 bills. I think Citi was one. There are probably some out there that still do."
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74o7r2 | If spiders' webs are the strongest fiber in the world. Why are not used as a material to build or create artifacts? | Technology | explainlikeimfive | {
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"It is really stretchy, like insanely stretchy, it may stop a bullet, but it will be behind you after passing through you. Spider silk is an amazing material, but it is insanely hard to get hold of, it took four years to get enough for a cloth smaller than a single sheet in 2009. Currently we cannot synthesise it very well ourselves, so maybe one day we will be able to use it.",
"Spiders are hard to work with. It's *possible* to collect spider silk and use it for fabrics but it's difficult and expensive- you can't mass produce the spiders. Spider silk is stronger than steel for the same weight, which isn't that much of a feat when you consider the almost negligible weight. A steel wire that thin would be easy to snap, BUT steel is easier to scale up, easier to mass produce, etc. We have other research into other fibers, taking what we've learned about *why* spider silk is string, without relying on an animal source for production.",
"Unlike silkworms, spiders will eat each other, so they're very hard to farm. They have instead made transgenic goats that produce the spider silk protein in their milk, but they haven't figured out how to spin it into a fiber yet"
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74oru6 | SMB vs FTP | What's the difference between SMB and FTP? We're doing this in class and we just finished doing both protocols but I still can't wrap my head around these 2 subjects. Thank you in advance! | Technology | explainlikeimfive | {
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"This isn't *exactly* what ELI5 is for, as you probably want something a bit technical. The ELI5 is that FTP is meant for plain old transferring files. SMB is more robust than that, and while you *can* transfer files you can also use it as a remote filesystem and do a bunch of other things with it. Please note: \"robust\" doesn't mean it's not a terrible protocol.",
"SMB and FTP have in common that they're used for remote access to files. They share this with SFTP (not to be confused with FTPS, which is FTP over SSL, SFTP is a different protocol built on SSH), NFS, WebDAV, and the largely-defunct AFP, among others. Where they differ is almost everything else. FTP is designed to have clients connect, download or upload whole files at a time, and go away again. That's great for distributing things that don't need changing, but not great for anything else. SMB is a *whole lot more* than that. Quite apart from files, SMB also handles access to printers (and a bunch of other stuff too, like sharing of serial ports, interprocess communication, and more - but barely anyone uses it for more than files and printers). Even narrowing the focus to files, it has a *completely different* model to that of FTP. Where FTP treats the files it serves as a sort of library, operating on whole files at a time, SMB acts as a remote *filesystem*. You can edit files in place with SMB, whereas the best you can manage with FTP is to have a client feature that fakes it (by reuploading every time you save a new version, and hoping nobody else is doing the same thing). Like local filesystems, with SMB you can place *locks* on files (which is particularly useful when altering them in-place, as mentioned before). SMB also has support for comparatively complex authentication schemes built in, whereas it has to be \"tacked on\" to the outside of FTP. That allows more complex, fine-grained access control, as well. Ultimately, they serve different purposes. If you want a rudimentary equivalent of Dropbox (albeit probably without automatic synchronisation), FTP does the job (though you should really use FTPS, or better yet SFTP). That's especially good if it needs to face the net at large. If, on the other hand, you want to share a proper filesystem between multiple users on the same local network, SMB is a far better option, especially if you need to muck around with shared peripherals as well."
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74py7b | How do programmers incentivize AIs | I often see it stated with little explanation in articles about AI research that programmers use incentives to get Artificial Intelligences to do certain tasks. They never say what the incentive is or how it works. How exactly does one go about giving an AI an incentive and what would that incentive be? | Technology | explainlikeimfive | {
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"Incentive is a misleading word. It's just a weight. Let's say it can do action A, or action B 50/50. If it picks right, you up the score +5, if wrong, -5. So if an answer should be A, and the AI picks A, it becomes 55/45, with a stronger weight towards A being the way to do things. It's not an actual consciousness, so it's not incentivizing like a person. it's just math that reweighs things if it gives the correct output. Here's some previous posts on the topic: URL_0",
"Incentives are basically what the AI wants. It’s usually expressed as a number and the AI is just finding ways to maximize(or minimize) that number. Let’s say you are making an AI to play Super Mario Brothers. The incentive would be the level count. You can also have several incentives that have different weights. So after maximizing the level count, you might want to maximize the score, or remaining lives, or how far to the right you got on a certain level. Level count is the most important, so moving to the next level might be worth 100 points, and the other things are worth 10 or 20, but that’s the idea. One of the complex parts of AI is figuring out how to set these incentives so that the AI does exactly what you want."
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74rqjg | Does having a random alpha+numeric+symbol password reduce exposure in compromised email data breaches? | Just received notice from haveibeenpwned that my email is part of multiple data breaches. when email info is compromised, what are the capabilities? I assume the hackers gained access to the salted hash password file. does having a random string strong password reduce exposure of brute forcing via rainbow? does a password that's 10 character random gen password like "jD02j-#2Ao" make it less likely to be flagged as a positive password match as opposed to what has been toughted as more secure "1quickbrownfoxjumpsover1lazydog" | Technology | explainlikeimfive | {
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"Brute forcing isn't the only way hacker try to guess passwords massively. One of the most common ways is through \"dictionary attacks\", and could be refined through word association. In your example, the password \"jD02j-#2Ao\" has 10 characters, and you would need to include all letters, numbers and a lot of symbols in a brute force attack in order to guess it. Let's say there's a set of 100 characters to pick, so that password is one of 10^100 possible combinations. On the other hand, the password \"1quickbrownfoxjumpsover1lazydog\" has nine words, and most of them are pretty common (in [this]( URL_0 ) list of the 3000 most common words, only \"fox\" and \"lazy\" aren't on the list). Let's suppose all of them are on the 5000 most common words list, so it's one of 5000^9 possible combinations (~2x10^33 ). But there's two notes on this: first, using \"1\" instead of \"one\" is a common substitution, and hackers tend to take them into account (also 1337 or SMS language). Second, that specific combination of words is a common phrase, and even if the hacker doesn't know it, it could be created from scratch if the algorithm can forms sentences using word function (so, \"adjective+noun+verb\", and combinations). It's difficult to calculate how much this fact lowers that 5000^9 , but it surely lowers it.",
"> I assume the hackers gained access to the salted hash password file. This is the best case. If hackers breached the site's security to get the password, we have already established that the site does have its security flaws. Whether or not they salted, or even hashed your password (or if they just stored it in plain-text) is uncertain. > does having a random string strong password reduce exposure of brute forcing via rainbow? Depending on your meaning of strong. If you mean a variety of characters, intended to thwart dictionary attacks and the like, then no, that will have no effect on a rainbow table. If you mean the length of the password itself, then yes, that could help. If the rainbow table was designed for passwords of lengths shorter than your own, then they won't be able to find your password in the 'table'. Also, if the website did salt your password, then this will render their rainbow tables completely useless even if your password was something simple like \"pa$$word\". Rainbow tables are effectively compact, but slightly slower lookup tables computed of the 'standard', non-salted hash function. However, I should address that having a stronger password will help thwart regular brute force attacks (just trying every single password to see if its hash matches) and definitely helps against dictionary attacks (trying passwords composed of typical English words + a few added symbols / digits, and often l33t t3xt). > does a password that's 10 character random gen password like \"jD02j-#2Ao\" make it less likely to be flagged as a positive password match as opposed to what has been toughted as more secure \"1quickbrownfoxjumpsover1lazydog\" Usually yes. Enough added characters in the longpasswordofjoinedwords will make it harder to crack than a more complex shorter one, but only for enough characters. Looking at it in a simplified case, lets say we want to calculate how many passwords there are of each type (with specific length and character set). If you have a password 12 characters long but all lowercase, that would be 26^12 = 9.5e16 possible passwords since there are 26 possible characters and we choose 12 (possibly duplicates, otherwise we'd have 26! / (26-12)! ). For the complex password, lets say its 6 characters long, but can be uppercase, lowercase, digits, and any of 8 specific symbols (!@#$%^ & *). That means we have (26+26+10+8)^6 = 1.2e11 possible passwords. However, the actual number of possible 16-lowercase-letter 'passphrases' (as they call them) would be lower, since not ever combination of letters makes a word. So a hacker may just pull words from an English dictionary, and try combinations of those instead. There's about 9k 5-letter (commonly used) words in the English language, and 18k 6-letter words. It'd take about 3 of these words to produce a 16-letter passphrase, so if we just computed all pairs of 3 as an upper bound, we'd have (9,000+18,000)^3 = 2e13, which is 3 orders of magnitude lower than our previous estimate. Of course this is a very rough estimate, and of course has its flaws, but I think you see the point I'm making. Anyways, in regards to your breached accounts- as always its a good idea to change your passwords on everything that used that same password, its even a good idea to have a different password for each website/app. Passphrases (as shown in my example) are stronger than complex passwords, and are easier to remember. If you do this, your main concern should then be what other personal info got leaked. Any phone numbers, full names, birth dates, that stuff. Getting your email address leaked can be a pain since you'll likely get lots of ads (due to them selling it to advertisers), but isn't as bad as potential identity theft. If any important info like that got leaked, definitely ask around (right away) and figure out how to handle that. I have no clue where to start on something like that, but I'm sure you could find someone who knows."
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74wto6 | Cell Phone Reception | My question is, why does cell phone reception always suck when there are a lot of people in one area? I was just at the expo for the Chicago marathon and couldn’t call my brother that I needed to talk to. Thanks in advance! | Technology | explainlikeimfive | {
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"Think of it as a noisy room. Think of the situation like this. In an empty room, you and your friend can talk to each other just fine. Then another two people walk into the room and also start having a conversation, but no problem because you and your friend can still understand each other. Then another two walk in and they also start talking and suddenly it becomes a tiny bit harder to hear what your friend is saying. And then another two enter...and another two...and another two and so on... After a while all these people talking quietly to each other start to make a loud background noise, and the more people who walk in, the harder and harder it becomes to understand what your friend is saying. Eventually the sound of all these people talking quietly to each other becomes deafening and nobody can hear anyone at all. The same kind of thing is happening with your cell phone. All those phones in the one place starts to cause a sort of interference or over saturation of the radio waves that carry the signal to the cell tower or reception station. To compund the issue, most of those people will be connected to the same cell tower and it has to suddenly deal with all that extra traffic. The same issue affects WiFi, which is why at busy conventions or on close knit streets where the houses are very close to each other, WiFi can become spotty to use and band hopping becomes necessary."
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74wvlx | why does the higher number of Frames per second equal to slow motion. Like why is 60fps a “normal speed” but 240fps considered Slow Motion. Why is 120fps not slower motion than 60? | Technology | explainlikeimfive | {
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"What makes something slow motion is when it's recorded at a higher frames per second than it's played back at. We normally play video back at 60 FPS. So if you record at 120 FPS and play at 60 FPS, the video is twice as slow, since every frame of video covers 1/120th of a second in time, but is played over a longer 1/60th of a second. But anything FPS can be slow motion if you play it back with a lower FPS than it was recorded at. You just end up getting a jerky video if you reduce the playback framerate too much.",
"It depends on the playback speed. For slow motion you'll record at a high frame rate but play back at a normal one. If you record a video at 240 fps and play it back at 60 fps then it will play back at quarter speed. If you play it back at 240 fps then it will play back at normal speed",
"The more frames per second, the more details you can capture of fast moving objects. If at 60fps a bullet moves from one side of the screen to the other nearly instantly, if you play it at 10fps you will see it \"jump\" from one place to another. If you film it at 120,000fps and play it at the standard 60fps you can see the smooth slow movement across the screen. A frame is like a picture. The more still pictures you can cram into one second equals less time between pictures (frames) and the more you can see."
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74xn9k | What's the big hurdle in getting people to Mars? Haven't the major obstacles to doing so already been solved? | I mean, we have: * Rockets to get materials to orbit * Capsules that can keep astronauts in space for a long time (i.e., ISS) * Relatively frequent unmanned missions to Mars That is: we can get people into space, in capsules that will *keep* them in space, and the ability to shoot those packages to Mars. I *feel* like shooting a person, rather than a robot, to Mars would be relatively simple, given the above--after all, each of the major problems, as I understand them, have been solved already. So what's the hold-up? What am I/we missing that is keeping us from shooting someone to Mars, say, *tomorrow?* | Technology | explainlikeimfive | {
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"Mars lines up with the earth about once every two years, so any mission would have to last at least that long, and would have to bring all the food, water, and oxygen needed for a stay that long. We don't have a rocket capable of moving that much material that far, much less come back. Also, all manned space travel, with the exception of the lunar missions, have taken place within the Earth's Van Allen belts. These form when solar wind interacts with the earth's magnetic field, and serves to protect us from radiation. We have no effective way to protect astronauts from the radiation beyond the earth's orbit. > I feel like shooting a person, rather than a robot, to Mars would be relatively simple, given the above Astronauts not only want to go into space, they want to come back home again, they are kind of whiny that way. You need to add a lot of extra fuel, then extra fuel to transport that extra fuel, etc., etc. This is called the tyranny of the rocket equation, as the amount of fuel you need increases exponentially with the mass of your payload. Finally, there isn't really any reason to send a person to Mars. For the cost of one manned mission, we can send dozens unmanned ones, and learn just as much with a greater chance of success.",
"We can't get enough mass into orbit. Your fuel scales significantly with increased payload and right now Curiosity and accompanying equipment is one of the heaviest things we have sent from Earth since the Saturn V rocket stopped launching with only Cassini having been heavier The Mars Science Laboratory had a mass of 3,893 kg of which Curiosity was just 899 kg. The rest was discarded in the process of safely getting Curiosity to the surface. That's it. We've only gotten 899 kg to the surface of Mars. You're going to need a lot more to get people there *and back* along with supplies to survive. In order to get more mass we need a bigger rocket, we don't have a big enough rocket right now. The Delta IV Heavy is the most powerful heavy lift rocket we have right now and it would only let you get double the mass of Curiosity to Mars, we need a Super Heavy Lift rocket like the Saturn V was.",
"Well, mostly the fact that, as it stands, it'd be a suicide mission. We have no way of sending people back to Earth. Also, those who get there would find a pretty unhospitable environment and hanging around to set things up is not an option. So the technology to automatically deploy a basecamp ahead of time isn't there, yet.",
"The biggest hurdle is storage. Mars doesn't have many resources so you have to pack for the entire trip. The ISS sees constant supply restocks throughout the year, but thats not possible for a mission to mars. You have to bring enough supplies to last the 6 month trip, once on mars you would have to stay for another year before your in an optimal position to return home, and then complete the last 6 month journey. That means bringing more fuel to successfully lift and move the massive amounts of supplies you are bringing. The problem with fuel though is that it has weight, so you have to bring more fuel to lift all that other fuel. A round trip to mars requires too many supplies at the moment."
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74yixg | how did clocks and time pieces work before batteries/electricity? | Technology | explainlikeimfive | {
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"You may have seen a pendulum swinging under a [grandfather clock]( URL_1 ). One neat thing about pendulums is that the period of the swing (that is, how long it takes to swing back and forth) depends on the length and weight of the pendulum, not how far it's swinging, so as long as the length or weight doesn't change the period won't change. If you are careful about constructing your pendulum, you can know pretty precisely how long it will take to swing and build your clock accordingly (such that, for example, every swing takes exactly two seconds, and each time the pendulum swings to one side or the other, it nudges a gear that nudges your second arm). You can also construct gears that don't constantly rotate the gear next to them, they ratchet the next gear one tick or tooth for every rotation. With very precise construction, again you can fine-tune your gears so that very slight changes in the speed of the gear providing power does not significantly alter the timing of the clock. There are mechanical devices with balanced weights that spin, and as they spin the centrifugal force raises the small weights up. When the weights are raised, it slows the machine; when they are down, it speeds the machine up. So it essentially holds itself at a constant speed, which you can use to drive the rest of the clock. The clocks were powered by springs and weights. In watches, there was (and often still is) a tightly-wound spring that slowly releases its energy in a way controlled by the gears attached to it. You would have to manually wind your watch often, and yes, when it was running out of potential energy stored in the spring it would run slow. People very often had to reset the time on their watches and clocks. (Side note: this was one of the reasons why church bells and large clocks like Big Ben were so important: they were large and reliable, and the ringing of the bells helped the communities around them keep time, usually because they didn't have personal timepieces, but also to know the time to reset theirs when they did). Clocks usually also have springs, but they also usually have weights attached to those springs. The strings or chains holding the weights are attached to gears attached to springs, and potential energy is stored by raising the weight to the top of the space under the clock. As the weights fall, they drive springs and gears, again controlled by those gears. The pendulum swung at a regular pace, as I explained above, and it was kept swinging by the springs and weights and gears attached providing it with energy to keep swinging. These days, grandfather clocks are more likely to be driven by electric motors and the pendulum and weights are purely for show. Back in the day, the clocks, like watches, would have to be wound [with a key]( URL_0 ) that raised the weights and put tension on the spring. The clock could also be calibrated by adjusting the position of other weights that pulled on the pendulum to change its period slightly. Bigger clocks could store more potential energy in the springs and weights, and the pendulums could be more carefully calibrated to be as precise as possible. That made bigger clocks more precise and more reliable (generally speaking; assuming it was a high quality timepiece in the first place)."
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74yvtb | How are we able to manufacture super small objects? | Like the transistors in a cpu for example. | Technology | explainlikeimfive | {
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"1) Print a pattern of the thing you want to make on a piece of photographic film. 2) coat a piece of silicon with a special material (called \"resist\") that hardens when light strikes it. 3) use a reducing lens to project that image, smaller, onto the silicon. The resist will harden only in certain places. 4) Wash off the un-hardened resist. 5) Now you etch the silicon, or add trace elements, or coat it with gold, or whatever you need to do to make your transistor or whatever. These changes will only take effect where there isn't any resist. 6) Wash off the rest of the resist, and repeat the whole process to add multiple layers or other kinds of detail.",
"An integrated circuit may contain a billion or more transistors, and a few billion connections. There are various kinds of process steps used to form them, most of which are done at high temperatures (but not all). Some of the layers are \"grown\" by exposing the silicon wafer to specific gasses that react with the layers already present, or which simply deposit materials on the wafer. Some of the steps etch holes through insulators at specific sites to create connections between conductive layers, or to etch away unwanted conductors. Some steps are done by aiming ion beams at the wafers at high energies so that atoms will be blasted into specific areas. The key to most of these steps is something called \"photolithography\". It doesn't help to do all of these layers if you can't chose where specific things happen. A chemical called a \"photoresist\" is deposited on the entire wafer in a thin layer. If you expose the photoresist to a specific color of intense light, it changes its ability to be later etched away by a chemical solvent. This is incredibly useful. The trick is to use a \"mask\" to block the light in some areas and let it through in others. If you shine the light through the mask, and then through a lens to reduce the size of the image, you can effectively print a pattern on the photoresist. After etching the photoresist (which only etches away in some places, due to the light masking you did) then the other process steps can also be selective. In addition to using lenses to reduce the image, the mask image starts off being quite small. It is created by a similar process, but instead of using a mask to control exposure of the photoresist, the image is directly drawn on the resist using an electron beam. Most of the layers are then done in an add/subtract method: A layer is deposited or grown on the entire wafer, photoresist is put on, the photoresist is exposed through a mask, and the photoresist is etched off in some areas and left in others (due to the masking I described). Then the wafer is subjected to an etchant that can attack the deposited layer, but the photoresist protects the areas where it wasn't etched away. So the stuff under the photoresist doesn't get etched either. After the etching of the layer, a different etchant is used to remove all of the photoresist so that you can get ready for the next step. There's also a process called Chemical Mechanical Polishing (CMP) that is used to make the wafer very very flat and remove residue from previous steps. The wafer has to be flat so that the images you project onto the photoresist doesn't get distorted and so that all of the layers can be lined up precisely, one on top of the other. This kind of process is repeated many times to build up different patterned layers of transistor parts, conductors, and insulators. After it is all done, the wafer is cut up into individual ICs which are then put into packages that allow them to be connected to circuit boards. This is a great simplification of the process that results in an IC. It will typically take a couple hundred individual process steps and result in an IC with around 10 layers of conductors (wires) connecting hundreds of millions or billions of transistors together into a circuit."
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74z16q | What is happening when a website goes down because of too many people try trying to access it? | Technology | explainlikeimfive | {
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"Somewhere within the computers the website runs on, some resource is being exhausted and can't handle the volume of work demanded of it. The rest only other components have to slow down, web requests get more and more backed up unlike the site comes unusable. The exact nature of the resource exhaustion varies, but somewhere in the web application, something has run out of CPU, memory, network, or disk capacity, slowing everything down."
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751is6 | eSIM, the tech behind Google Fi | Read this [article]( URL_0 ) which says how Pixel 2 is equipped with eSIM and would be able seamlessly switch between networks, thanks to Google Fi project. How does this eSIM works in real? | Technology | explainlikeimfive | {
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"At the heart of it, a SIM card is basically a unique identifier that is used to tie your account to a device. Your SIM card is actually just a number that boils down to something like this... FG567-56721-65431-124AB-1212Z That's not the exact format of a SIM identifier because they differ from country to country, network to network but you get the idea. The SIM card contains the identifier and some secondary data needed to encrypt your call. Now the reason SIM cards have shrunk over the years into the nano-sim format used in modern smartphones is because in years gone by, people would also store their contacts and some other small bits of information on them. This does not happen any more so they have been able to shrink it's size. Also, people realized the protective board size was superfluous to requirements. Did you know the reason SIM cards arrive in those credit sized cards you pop them out of is because originally, that's how big SIM cards actually where! The whole card would be put into the phone! They no longer do this but to conform to the GSM specification, they need to be able to fit into all sizes of GSM phone, despite the last phone to use credit card sized SIM's disappearing many years ago. Some time ago people looked at CDMA phones, some of which have never required a SIM card because they use a unique identifier built into the phone itself, and thought \"Well why not do the same thing with GSM phones\". The idea of the SIM card was portability, you could take a SIM out of one device, put it into another and have swapped devices or networks in seconds. However at the end of the day it's still just a physical component that carries a piece of information. A piece of information that could also be entered via a barcode. So e-sim was born. Instead of putting a card into the device that then reads the data from it, the phone has a fixed storage area and a unique identifier (Known as it's IMEI code) for the data that you input either by hand or by scanning a barcode or the network can push to you once it sees the device IMEI code trying to register on the network. The advantages are many... * You can flip between networks at the touch of a on screen button or even automatically instead of searching for paperclips and swapping fiddly small components. * Makes multi sim phones easier to implement so you can have two or three networks active at once (Hardware permitting). * Makes call distribution a bit easier. * Devices can be smaller and more waterproof as there's no longer a need to fit a physical tray and the access needed for the sim card to be put into the phone. And a whole host of other advantages. Of course, there are claims that it will make cloning easier to do and less technologically savvy people will find it harder to implement but both these claims are just rubbish really. The simplest way to think of it is a SIM card that is built into your phone and not removable, but now it's rewritable with a new networks info!"
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751qnk | How does coding actually work? | So, from what I understand a code is a line of instructions that build websites, games, programmes on computers etc. To do this you use a coding programme. That coding programme will have been built with a code, using a coding programme. That coding programme would have also been built with a code using a coding programme - right? So where does the coding begin? How does it start? I'm so confused. | Technology | explainlikeimfive | {
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"Here is my explanation, from a computer engineering perspective. Sorry about the wall of text, hopefully it's helpful. Reducing it all the way down, code maps to transistors. Think of transistors like little on/off switches in a circuit. Applying electricity in the right way lets you flip this switch as desired. We can cram a ton of transistors into a microchip, and modern computers have billions of these things. So, how do transistors help us do anything? The answer is related to the lowest level of computer code...binary code, the 0s and 1s. Each 0 or 1 is called a bit. Each bit represents the on/off status of some physical transistors. It probably still isn't evident how that helps anything, though. The first big advantage of having all these little switches, is that we can use them to do stuff that requires logic. Boolean algebra is a type of algebra used to represent logic, where variables are true or false (1 or 0). Using this tool, you can basically map out any logical rules, like...if this thing happens, do this other thing. This mapping is really what computer programs are, a big set of logical rules used to compute stuff. The other big advantage of using transistors is that we can also represent numbers using just bunch of 0s and 1s. Think about the normal numbers we use, and how everything is based on the number 10. Binary numbers work on a similar way, but everything is based on the number two. The details aren't really important, but the point is that we can use a sequence of binary values to represent a standard number, like 10101010=170. Any computer program is built up by combining logic and numbers in useful ways. A microprocessor has some simple little programs to help you out, called an instruction set. These take care of stuff like adding, multiplying, etc. You make programs at this level using the instruction set, but it's very painful (some people enjoy it, but I'm not one of them). It's also hard to make complex programs, because combining all these simple operations in the correct way gets complicated fast. This is where programming languages come in. To greatly oversimplify it, you can think of a programming language as a collection of rules and programs that make your life easier when trying to create a new program. The language takes care of all the low level stuff, so you don't have to. Creating code at the machine level vs using a higher level language is kind of like trying to swim across an ocean vs. using a boat. Sure, you might theoretically be able to do it, but you are much better off taking the boat to avoid drowning. Programming languages can vary quite a lot on how far they take you away from the machine level stuff. Nowadays, you can be a very proficient programmer while knowing very little about what the machine is doing at a fundamental level. That's a good thing really. I think this is also something that probably doesn't occur to people outside tech, that hardware and software have diverged enough to be separate skills. In the old days, they were really the same thing. Bottom line, code is just a tool we use to share and store ways to flip switches for some purpose. Fortunately, lots of smart people figured out the code for commonly needed tools and combined them into programming languages. This allows us to build onto code others have already made and avoid re-inventing the wheel every time we make a new program.",
"Coding programs translate the code you put into it to 'machine code' (this may not be the correct terminology but I think it is). Machine code is the code the motherboard understands. Motherboards respond to the code given to them by moving around electrons through transistors and whatever other electrical stuff makes up the computer, which gives the outcome we asked for. Coding programs is just like a translator. Translating from one language we understand, to another the motherboard understands. You can program in machine code, but it is a lot more complicated than other coding languages (this is how you create coding languages, connect up machine code to the coding language similar to connecting up the word 'hello' across different languages). Which is why coding languages exist, to make it easier to code stuff. Because machine code naturally isn't easy to understand, I'm pretty sure it's just a sequence of 0 and 1's, or binary. Reading a sequence of 0 and 1's is meaningless to a human, but coding languages all have dicationary words which we understand even if we know nothing about coding.",
"Computers can't really do very complicated things. They can just do very simple things very quickly. By doing very simple things very quickly they take on the appearance of doing complicated things in real time. The kind of things a computer can do are:. Moving data. Saving data. Adding data. Incrementing data. Deleting data. Now say we want to do something else. Something like multiplying. A computer will likely do multiplying by adding lots of times. So 3 times 8 becomes 8 + 8 + 8. We can call this new procedure \"multiply\" and let a human use it to save time. You are now starting to move away from what the computer is actually doing and instead devising a way of representing computer language in a higher level language. Next you might want to have a way of representing how we do percentage calculations. The calculation at human level is current quantity/total quantity * 100. At machine level this will be a complex series of additions, moves, saves etc. But now you are starting to create the building blocks of a high level language. We can do this for all the normal functions you might want to use: percent; mean; highest value; etc; etc. Now we hand over all the building blocks to a person, a programmer. Now that programmer wants to create an application to work out tax on a salary. He already has a percent function but in this language he doesn't have a tax function. So we let him build his own set of instructions based on the higher level instructions we created for him in the last paragraph. The programmer goes away and writes a function that takes a salary and returns the tax to be paid. Now this is still a series of adds, moves, saves and swaps but it is hugely more complex than than just the multiplication function that we initially started with. So we let him name his function so he can use it again. That's pretty much it in a nutshell."
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751ro0 | The location methods used by explorers like Columbus to record their findings and navigate home | Technology | explainlikeimfive | {
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"[Columbus was the first sailor who kept a detailed log of his voyages. We therefore know how Columbus navigated, and that he was a dead reckoning navigator. On the first voyage westbound, Columbus sticks to his (magnetic) westward course for weeks at a time. Only three times does Columbus depart from this course: once because of contrary winds, and twice to chase false signs of land southwest.]( URL_0 ) Columbus made very good time on some days of his voyage, as good as sailing vessels achieve."
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751sdn | Why does resetting my phone often fix bad signal strength? | Technology | explainlikeimfive | {
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"Doing a reset wipes the cache files. These can cause random software issue. In the case of signal, resetting the phone forces it to restart searching for signal.",
"1. When restarting your phone, or toggling airplane mode on or off, it causes your phone to search for a tower and establish a new session 2. Based on where you are and the primary provider in your region, you may be triggering QoS policies to apply to your session which downgrade your data to a lesser service which has differently tilted and aimed antennas. When you reconnect to the service, the QoS policy resets or other events cause your traffic to return to a normal priority. This is common for when you are dropped from LTE to 3G/EVDO. A lot of carriers will downgrade competition's customers to make room for their own customers. For example, if AT & T has 97 customers on a tower and 5 Verizon customers attempt to join, three of the sessions will remain at LTE while the other 2 will be 3G/EVDO. 3. The firmware which controls the antenna and connectivity portion of your phone may have experienced resource issues or a software bug. 4. Your phone's operating system may have experienced resource issues or a software bug 5. You live or travel through a location where two or more towers are aimed at and your session is improperly being handed off.",
"It will renegotiate with the closest tower as well. It is possible you will pick up off a different tower."
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7524x4 | Electricity and the difference between volts, amps, watts, etc. | Technology | explainlikeimfive | {
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"A good metaphor for electricity is water flowing through a river. So, voltage is the speed of the water flowing through the river, amperage is how much water is flowing trough the river and resistance (Ohm) is the resistance of the flow. There are always some obstacles in a river, like rocks or curves. This is in fact, is the same in electric conductors, like in copper wires. If you combine all factors, you have the amount of water that is flowing trough the river in one second. The calculation goes: speed (voltage) x amount of water flowing through the river in one second (amperage) x obstacles, resistance in the river (ohm) = amount of water (wattage). In short it is P = R X I^2."
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752b1f | What exactly are "frames" in video games, and how do you quantify them? | I hear so much talk about the amount of frames per second in video games and I understand roughly that more frames per second=better graphics, but how can you tell the amount of frames per second a game has without explicitly being told, and why are they so important? | Technology | explainlikeimfive | {
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"A video is just a rapid sequence of pictures, or frames. Once you get too few pictures per second, the movement doesn't seem smooth anymore. By increasing the number of pictures shown to you every second, you decrease the probability of that happening. Of course creating so many pictures requires high processing power - the more taxing a single image (referred to as: \"better graphics\") - the more so.",
"A frame is just a still image. By displaying a sequence of still images rapidly enough, you create a sense of motion. The number of frames per second defines the temporal resolution in a video game. Or, in layman's terms: more frames per second = more stuff to see for the eye when things move around. This doesn't necessarily mean that the graphics are \"better\", but any motion will feel more fluid and immediate. The quantification of FPS is fairly simple: you have a counter that counts up when a frame has finished rendering and after every second, that counter is displayed and then reset to zero. If you want to refresh the FPS counter more frequently, you reset after 0.5 seconds and double the counter value, for example. If the game doesn't have that functionality, then the tricky part is to find out *when* a frame has finished rendering. Tools like FRAPS hook themselves to the graphics API of a video game that tells the graphics card what to render and also use it to display the frame counter.",
"A lot of people answered the question about what frames are, but the reason why they matter in video games is that the more frames you have, the more \"windows\" there are for your game to accept button/mouse inputs, which can make all the difference in high-level gameplay. For example, if you ran a game at 10FPS, not only would it basically look like you were playing a video game with a PowerPoint presentation, but that means the game will only register a maximum of ten inputs in one second. For some very fast-paced games, milliseconds of reaction time can be the difference between a win and loss."
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752bwn | what is Ngnix ? when and why should you use it for your app? And how would you integrate it with the cloud-hosting services such as heroku? | I keep running into Nginx everywhere I go, I read its a web server and all but it was slightly confusing and I didn't understand when I would need to use it or if I should And more importantly how? Something about all the examples stumped me. | Technology | explainlikeimfive | {
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"It is a solution to the C10K problem. With a typical web server, each HTTP request is a thread, and most computers start have serious performance problems once they reach a certain number of threads (sometimes, but not always about 10,000 threads). At that point, you need more web servers, no matter how big and strong your hardware is. Ngnix is a Linux based solution that uses an event-driven web server that doesn't assign a thread to each connection, making it more scalable. They also have an email server that takes the same approach. > And how would you integrate it with the cloud-hosting services such as heroku? There is really nothing special with Ngnix when it comes to the cloud. If Ngnix is one of the OS images they can spin up for you, you use it on the cloud like any other application stack.",
"Nginx is a web server comparable to Apache, IIS, and lighttpd. Nginx does a couple of things really, really well that make it ideal for certain configurations. 1.) It serves static content (content that doesn't require any back-end work, such as access to a database, running Python/PHP/Perl/CIL scripts, etc...) extremely quickly and with almost no overhead. Proactive sysadmins will often have a single Nginx server handle static content requests, and then pass dynamic content requests through a load balancer to multiple Apache servers. 2.) It can handle a huge number of http requests at once without choking. As long as these requests are simple, such as a static content request or an idle connection, nginx will run laps around its competitors."
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752mam | The artificial nose technology used in food processing | Recently, I heard that there are machines which can differentiate between ripe and damaged foods by SMELLING them and they are used in food processing and manufacturing. Can anyone explain me what is the machinery and how it can do such a complex task? | Technology | explainlikeimfive | {
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"Most foods give off some very specific chemicals when rotting. So the \"artificial nose\" is not very fancy -- it's just a gas chemical detector, and when too much of one indicator chemical is present, it marks that this item is rotting.",
"It probably is not actually smelling the foods but for example certain fruits and vegetables will release ethylene gas upon ripening. So it would be detecting the presence, or lack thereof, of these molecules in proximity to the given produce item."
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7550rg | If hackers are using "brute force" password guessing, why can't websites lock them out after too many guesses like they do legitimate users? | Technology | explainlikeimfive | {
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"That's exactly what happens. However, when there is a leak (data security breach) and they get their hands on the encrypted password file, then they get infinity tries to decrypt it.",
"Generally speaking, websites do have timed lockouts. The problem comes when a hacker gets their hands on the encrypted password file, then their number of tries per second is just limited by hardware.",
"The idea is that this is happening offline. The hacker can have the password hashes from the target machine via some other hack. They're attempting to find any password (not even your password) which fits the site's restrictions *and* has the same hash as your password. The hacker could also just have encrypted communications, and possibly their plain text (or an idea of what the plain text looks like). This is the case of wifi password hacking, where given sufficient encrypted information, you can start eliminating possible passwords then brute-force your way to finding one that decrypts all the info you have, and thus must be the one that will let you login."
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755m4f | Why are audio jacks round while charging and other ports are rectangular? | Technology | explainlikeimfive | {
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"Audio jacks and *some* charging ports use so few wires that they were able to use a \"coaxial\" round design. This enables them to be connected in any orientation, and to rotate freely in the socket, both of which are advantages. These connectors don't work well for digital data (the rotation can screw up the connection momentarily) or for cables requiring more than about 4 wires to be connected.",
"With an audio jack the contacts are arrayed down the length of the plug, meaning the first contact could connect with every other contact along the way in or out. Pumping charging voltage down a data line is a bad idea."
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756le4 | why do we have 4k monitors and 144 Hz monitors, but not 4k 144 Hz monitors? | Technology | explainlikeimfive | {
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"144 Hz 4K video requires so much data that only the DisplayPort version 1.4 can support it and it was only published in March 2016. Even that requires use of Display Stream Compression which is a mostly lossless form of data compression. Basically it is just too much information for hardware to handle until very recently.",
"They make 120Hz in 4k, 1080p had some 240Hz as well. There is a bit of an issue with cabling. HDMI can only push about 60 frames a second at 4k. Displayport does a little better, getting up to 120Hz at 4k, and potentially reaching 144 or 240 with display stream compression Then you get into issues with actually tryign to find a source that's going to give you a feed at those rates.",
"Your screen works like this: your pc prepares an image in its memory, and then it sends it over to your monitor. Now your gpu, that is transmitting the data needs to be fast enough tontransmit everything you want, and the electronics in the screen must be fast enough to receive all the data. Lets say that you have a 1000x1000 pixel screen and you refresh it 50 times a second (50hz). That is 50.000.000 pixels per second. Now if you want to double the resolution you could go 2000x2000@50Hz that is 400.000.000 pixels per second. If you want to do 1000x1000@200Hz you end up with 400.000.000 pixels per second again. Doing both (2000x2000@200Hz) requires an insane amount of 1.600.000.000 pixels per second. Now your gpu and screen both have maximum pixels per second value, so you have to do the tradeoff depending on what you want: more pixels or faster refresh rates"
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7577ap | With all the stuff happening around YouTube’s policy towards content creators, why can’t they move/create a new alternative to YouTube? | Technology | explainlikeimfive | {
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"They can move, there are other sites that you can host videos on. Dailymotion, Vimeo, or their own website, are all viable options. However, there's a pretty big downside. They don't have large audiences. For every successful channel, they will have a subset of viewers who watch religiously. People who can be relied upon to continue to watch regularly. But they are very much in the minority. Most viewers of a channel are nomadic. Watching the videos they come across. This is why it's best to be on the biggest platform. You've got the most people who can find your content. Switching to a different site is a risky move. How much of your audience will follow you to the new place? It will likely only be a portion of those dedicated viewers. Which means by doing so, you'll be decimating your audience by a single act. Most viewers probably won't follow you to the new site. And that site has far less viewers to discover your work there. It's not a beneficial change to make... yet. If you want to stop youtube from being the dominant video platform, use a different platform primarily. Content creators will follow the audience.",
"People won't necessarily follow you to a new platform. I used to religiously follow a particular author's weekly ESPN columns. Easy to do since I went to ESPN every day. He moved to another platform. Even though I liked his columns, I never bothered to find out which platform he was at. I went to URL_0 all the time, not whereever he ended up. Same thing with youtube. You may religiously watch a particular person's videos on youtube. One guy leaves to vimeo, you may or may not switch. But a lot of people are just people who see his videos on their youtube feed. If they switch to vimeo, only a subset of people will follow them. The rest will just watch other youtube videos instead.",
"Moving to a new platform would simply have the effect of moving the problem. The issue is not YouTube arbitrarily deciding to punish some people by demonetizing their videos: the issue is advertisers not wanting to have their products associated with contentious things like terrorism, political extremism, violence and so on. If content creators moved en masse to a new platform -- they'd have to do it en masse if they want to compete with YouTube -- advertisers would start telling that platform they don't want their products associated with those things.",
"It's like another search engine trying to beat Google. It just isn't going to happen. YouTube is too old and well known. People like what they know."
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759ohg | Why deploy all 10 Iridium-3 Satellites in the same location? | I'm referring to the launch this morning: URL_0 I've played KSP a bit, so that may be getting in the way of me understanding this. I would think, the satellites are going the exact same speed as the delivery vehicle they're attached to. During separation, they aren't being propelled away more than the separation force (which doesn't appear to be sustained). This would mean (in my head) that all 10 of the satellites would be clustered extremely close to the delivery vehicle. I would think that you would want the satellites as far apart and on different trajectories to ensure maximum coverage. | Technology | explainlikeimfive | {
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"The satellites presumably have a small amount of fuel on board. It doesn't take much fuel to tweak your orbit a bit to get the satellites all following the same orbit but spaced out around the orbit. Just dumping a satellite out into space is a great way to quickly lose the satellite. The real world isn't as clean as KSP. Orbits drift for lots of reasons–solar wind, solar radiation pressure, nonuniformities in Earth's gravitational field, the remnants of the upper atmosphere, etc. If you want a satellite to stay in the orbit it's meant for then it needs the ability to use a little fuel to tweak its orbit.",
"In the article I read they will be spaced 30 degrees apart on the same orbital plane. One degree is 107 km, so 30 degrees is 3210 km between satellites Edit: the circumference of the Earth is 40,075 km. 10 satellites spaced 3210 km will cover 32,100 km or 80 % of the Earth on that orbital plane",
"As already mentioned, once you have a bunch of satellites in an orbit, with engines attached, it really doesn't take much effort or fuel usage to get them to occupy different positions in the same orbit. If the satellite fires its engines in the direction of its travel (prograde), it speeds up*, but the height of it's orbit on the opposite side to where it currently is goes up, making the orbit longer. It turns out that these two effects don't completely cancel out, meaning making your orbit higher makes it slower. The satellite just needs to complete its orbit to end up behind the rest of the satellites. Once it completes the orbit it will also be at the same height it started at, so it can fire its engines retrograde to slow down and return it's orbit's shape to the original orbit. To make larger changes in position, it doesn't need to make larger and larger orbits burning lots of fuel, it just needs to make a slightly larger orbit and wait for as many orbits as needed to get into the right position before returning to the original orbit. The same can be done the other way: firing retrograde slows you down*, but makes a smaller, quicker orbit that can be used to get ahead of the rest of the satellite cluster. *In eccentric orbits, your speed varies. Firing your engines prograde makes you faster at the point where you are, but when you reach the opposite side of your orbit, you will be going at the same speed as if you hadn't fired your engines, but you will be higher.",
"Yes, you want the satellites spread out in different orbits, but even a couple of m/s (the spacecraft move several spacecraft lengths in the second before the view cuts away) makes a big difference. There will be some fine-tuning with thrusters, but the parking orbit is the right speed to orbit the Earth at that altitude. The cost savings from sharing the launch vehicle more than makes up for the extra fuel and time to spread out the orbits before the satellites go live."
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75bn7o | If the human brain is such an incredible computer, why is a humble calculator quicker and more accurate? | *at math... | Technology | explainlikeimfive | {
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"The human brain is *not* an incredible computer at certain tasks, such as math calculations. I mean, it's incredible compared to many other brains, and even some of the earliest electronic computers. But it isn't good at specifically doing math computations compared to a digital computer. However, human brains are much better at things like pattern recognition than all of our current engineered computers.",
"That's like saying if our hands are so great why can't we pull out staplers as efficiently as a staple remover? Because it's a fucking staple remover designed to do one thing.",
"Because it's not a discrete input output machine but rather a fuzzy logic probability machine",
"A calculator is good at basic math, and *only* at basic math, because we specifically created it as a tool for doing basic math. Contrary-wise, the human brain is a product of billions of years of evolution selecting for survivability. It has to be good at interpreting a variety of input signals, coordinating body movement, building a mental model of its surrounding environment, distinguishing friend from foe, and navigating a tribal social structure. For the vast majority of the history of brains in general, they have never been asked to do math, and never needed to be good at it. The brain-as-a-computer concept is a metaphor, and one that only stretches so far.",
"A calculator works off a predefined set of rules and arithmetic, and thats all it has to do. Your brain is juggling dozens of subconscious functions on top of the conscious ones and can extrapolate information from incomplete data, a calculator specfically can not do this unless it has been programmed to do so."
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75e2mr | why dont they make a USB connected laptop charger? | Technology | explainlikeimfive | {
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"They did, and they have. The primary reason usb wasn't used is because people are prone to killing their usb cables by constantly putting it in the wrong way, that's just the last thing you want from a cable. But, with the advent of USB-C quite a few laptops and monitors have been popping up that have a usb-c port which is just stellar because i can use my charger for my Nexus 6p The laptop I'm currently using that has it is a chromebook acer 14 for work.",
"In the USB 1.0 and 2.0 specs, a standard downstream port is capable of delivering up to 500mA (0.5A); with USB 3.0, it moves up to 900mA (0.9A). The charging downstream and dedicated charging ports provide up to 1,500mA (1.5A). Basically, it would take a long time to charge."
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75gcyc | How do countries with multiple timezones have different TV channels? | I'm from New Zealand, which has one timezone, so it's just one TV broadcast. However, countries with multiple timezones, like Australia, USA/Canada, Russia etc have multiple timezones. Suppose I live in New York, on the East Coast, and I have a friend in Los Angeles, on the West Coast. How would TV channels and stations make it so our TV adverts are seperated (ie, I wouldn't see an ad from LA saying "limited time car offer for 50% off, 9am to 3pm only!") since I'm in a different time zone and it's totally irrelevant to me. So channel one in LA would have a different programme to channel one in NY, but it's still the same channel? Not sure if this makes sense but someone dumb it down for me thank u | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"First lets talk about network TV. In the US there are 4 major networks. NBC, CBS, ABC and FOX. These networks have affiliates in different markets. NBC has 222 affiliates which show the national feed, and also run their own programming for local news, local specialty shows, syndicated shows, etc. If you are watching NBC you're watching one of these affiliates, usually the one closest to you geographically, even if you are getting your TV delivered via cable or satellite. The US is large, but widely populated. When television was primarily broadcast via VHF radio, it had a relatively short propagation distance, usually well under 100 miles. More likely under 40-60 miles or the signal would be very bad. A state like Ohio has a number of network affiliates, something like 9 NBC affiliates across the state. Columbus, Ohio and Cleveland have their own stations and own local news/programming. When it comes to advertisements, There are national ads and regional/local ads. During, say, the Superbowl, most of the ads you will see are national ads that everyone sees. However, there are some slots which are sold locally. The local affiliate will play their own ads basically on top of the national broadcast. Cable works similarly, with the cable provider selling local ads. Back in the day, you essentially had a person waiting to press the button to insert those ads, now I believe its more automated, with the network sending a background signal which lets the local equipment know where their own programming can be inserted. Large networks like the big 4, but also others like HBO and Showtime have both east and west coast feeds. They want to show the popular shows during prime time. The problem is, 8PM on the east coast is 5PM on the west coast. You don't want to start your late night programming at 8:30 PM on the west coast either. So you have the Eastern and Central watching one feed and Mountain and Pacific watching another. For big live events they show the same programming across both feeds, but for the most part the west coast feed is running 2 hours behind the east coast. So the TL;DR is that the US is large. We have a lot of different TV stations which broadcast some of the same content, but also have their own local programming. Local broadcasters or cable networks/satellite providers have the ability to insert their own ads into nationally broadcast programming where appropriate.",
"> but it's still the same channel? It isn't the same channel. If your name is Pat and another guy you meet is also named Pat, are you the same person? Just because there is a CBS in NYC and a CBS in LA doesn't mean they're the same channel. They're both owned by the same company, but different channels entirely."
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75idsk | Are Rechargeable Batteries Better Fiscally/Environmentally vs. Disposable Ones? | Technology | explainlikeimfive | {
"a_id": [
"do6eh78",
"do6eu2a",
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"text": [
"Fiscally no question they are better. Environmentally I am unsure. But the energy required to charge a AA battery costs pennies so assuming you use them regularly they will make their money back quickly.",
"Because you only buy them once, and you don't throw them away. One $10 battery costs less than 100 $2 batteries, and throwing away 100 batteries is more trash than throwing away one battery.",
"Rechargeable batteries are absolutely better than disposable ones environmentally, including all aspects of their life, ie. including production, use, and disposal. It's difficult to condense a life-cycle assessment into an ELI5 but across the board for factors like acidification, heavy metal pollution, and climate change contribution rechargeable batteries (assuming an optimistic recharge number) range between 50 and 140~ish times less of an impact. The biggest impact comes from the production of the battery itself. [Source]( URL_0 )"
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|
75kr2z | Why do "download speeds" and actual update/install speed differ drastically? | I'm sure many people have experienced this - but I'm so fed up with these installs and updates taking hours. When installing that includes a "MB/s" counter, the install begins with something like "5MB/s" and then slowly slips into the "8KB/s" range. This is all while my speeds, according to URL_3 , are somewhat high. Someone, please explain why this difference exists. Screenshots - Overwatch update - URL_1 URL_0 - URL_2 | Technology | explainlikeimfive | {
"a_id": [
"do6xiwt",
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"text": [
"There are three major factors that determine the speed of a connection to a given website or server. * Your connection speed to the internet via your ISP * The website/server's connection speed to the internet via *their* ISP * The amount of traffic on the internet between your ISP and theirs. A speed test can only check the pathway between you and the speed test server. So the only useful information a consumer can get from a speed test is whether their connection to the internet via their ISP is as fast as the ISP claims that it is. But your connection speed through your ISP is irrelevant if the server you're trying to get information from has a slower connection or has a high number of other people trying to access it or there is a lot of traffic on the internet pathway between them and you and in most cases it's a combination of all of it.",
"Becuase its based on a lot of variabls like RAM, CPU Speed, Software speed, non client server speed, traffic flow and somtimes the weather can effect it. If it keep happening though, id contact your ISP."
],
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75muje | How are those who use card skimmers and other means of fraud not immediately traced and prosecuted? | Technology | explainlikeimfive | {
"a_id": [
"do7ewda"
],
"text": [
"It can be extremely difficult to determine who placed a skimmer, especially if the placement was done stealthily. The skimmer itself should contain little to no personal details about who placed it. Some skimmers can communicate wirelessly and may never be physically retrieved by that person, making it difficult to trap the person. Once that person has credit card information, that person is likely to sell off the data to others, making it difficult to trace who originally captured the numbers."
],
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3
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|
75qiho | is it possible to see within pixels? | Technology | explainlikeimfive | {
"a_id": [
"do84qjh"
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"text": [
"The results you are seeing are errors introduced by the image compression process. Pixel-based digital image files have a maximum number of pixels, and smaller that that there is actually nothing. There *are* images described in ways other than pixels, using math. Some of these can be zoomed into forever, as the computer will construct the missing details on request."
],
"score": [
8
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|
75rkii | How is a timetable for frequent rail service (e.g. the London Tube) made, with trains arriving every few minutes and sometimes different lines? | Technology | explainlikeimfive | {
"a_id": [
"do8ivlw"
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"text": [
"Well they know exactly how long it should take for a train to do the run, how long it is between each station and how long they need to stay at each station. They'll typically measure these numbers and record all of them (for new lines this might be done by running empty trains in pretend service). Then they set a start time and location for a train, and then pick a time after it that gives it enough space (so at the station that takes the longest to load/unload, the train behind it isn't so close that it catches up and has to stop). And they just keep scheduling trains one after the next to get an appropriate number of trains (depending on passengers, money, and number of trains they actually have). They also need to ensure that the shared spots on the line (like tunnels) where multiple lines share the same track are not overloaded, so it's usually these areas that they base the scheduling on (like if the math shows the tunnel can handle 10 trains per hour, and it has three lines, they schedule the three lines so they meet the max number in the tunnel, and select the start times so they always arrive in their \"slot\". In practice, once they have a schedule they really run it, and as people and life changes, they identify things that are under/over utilized and adjust the schedule to match (so the tunnel might handle 10 trains per hour, but the red line gets late during rush hour, so add time to it's schedule and reduce so it don't hold up other trains). Similarly, better tech is installed on tracks so they can fit more trains on it and that too will allow for more trains and requires the schedules to be redone."
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75t265 | Whyvare some digital watches faster or slower than others? | Technology | explainlikeimfive | {
"a_id": [
"do8qzw0"
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"text": [
"Nothing is perfect, there is always some error. In digital clocks there is a circuit called an oscillator. It's the electronic equivalent of a pendulum, but instead of an object moving the same path at a fixed rate there is a voltage that swings up and down at a fixed rate. This acts as our little electronic clock tick, making a clock work in seconds/minutes/hours is just done by counting the ticks. The catch is that we usually use tiny pieces of crystal as our oscillators. The rate they tick is dependent on the size, shape, and chemical makeup of the crystal. Because these things are built with physical tools that have limits (how pure can you grow quartz, how tiny can you cut it with blades or a laser, how much stress is put on the crystal when you connect leads to it, etc) there is always going to be some error in the specifications and the physical component. Now you can arbitrarily lower that error, it's just a matter of cost. Since most people don't want to spend hundreds of dollars on a clock, we can accept that it will go a little bit faster or a little bit slower than desired. There are digital clocks that are much more accurate than quartz clocks, but again they're extremely expensive and rely on things like radioactive decay."
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75t4nf | Does water in spaceships short circuit anything? | Technology | explainlikeimfive | {
"a_id": [
"do8q7nu"
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"text": [
"Yes and no. The vast majority of exposed electronics on the ISS are carefully sealed and protected, just in case there's an inadvertent water spill. The stuff needed to maintain normal function is safe, and so is the really expensive equipment used for experiments. However, there's still tons of traditional electronic equipment up there that could be damaged. Laptops, normal household devices, etc."
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75u4jq | How do computer board designers change and update parts like GPUs and motherboards to be compatible with all types of new and old standards, and make them faster, so quickly? | Technology | explainlikeimfive | {
"a_id": [
"do8zob1"
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"text": [
"In a word: Standards. If your part doesn't comply with the standards for that part, it won't work with anything else. Which means nobody will buy it. New standards are sometimes backwards-compatible. Sometimes they are not - so part manufacturers don't *always* make stuff compatible with everything else. Add to that that there *are* companies that just make everything themselves, or have it made for themselves, and don't *care* if it's compatible."
],
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75yltj | How do you “crack” a game? Why can’t you just send the files of the game to someone so they can play it? | Technology | explainlikeimfive | {
"a_id": [
"doa0ahn"
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"text": [
"Developers of games and other software don't want people to buy one copy then upload it online and have everyone else use it. To prevent it, there may be a number of different techniques implemented in the software that only allows the software to run under certain conditions. Older games required the physical CD to be in (and in a portion of the CD that wouldn't be copied to disk by default). Even older games required some line of text from the user manual to be copied. Newer games tend to rely on online registration of some sort. Crackers take the software and decompile it. That is, they recreate the original source code from the compiled machine code. They proceed to scan through the software and remove the various checks that validate it. Then they recompile it, resulting in a program the does everything the original does without the check. This whole process can be quite complex, especially if the developers purposefully obfuscate the code (ie. make it more complex than necessary to make it difficult to read). Nevertheless, teams of crackers often work together to create a cracked version they can upload."
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760h8m | How do domains work, like .com .ru? Why can sites like discord use a custom domain like .gg? | Technology | explainlikeimfive | {
"a_id": [
"doabppg"
],
"text": [
".gg isn't a \"custom\" domain. It's a top level domain registered to \"the crown dependency of Guernsey\" (I've never even heard of the place). The little small countries like Guernsey have TLDs allocated to them and then they can either hold on to them or turn around and sell domains registered under their top-level domain and make some money off the dea."
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762303 | If computer code is written in a software interface, what did the person who wrote the code for the interface use? | Technology | explainlikeimfive | {
"a_id": [
"doaqfyt"
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"text": [
"The very first programs were written by physically setting switches by hand Then came punch cards and tape which could set switches automatically Once you move to \"writing\" you're talking about writing in assembly. There are basic instructions and how to execute them baked into the chip. It reads in the he code for ADD and the appropriate switches get activated Once you've got assembly going you can write something to let you write in assembly. With that you can write a C compiler, and it's turtles all the way up to stuff like Java and JavaScript"
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7629pb | What does NASA use their 90Gb/s internet speed for, and why does it have to be so fast? | Technology | explainlikeimfive | {
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"doasd9l"
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"text": [
"I am unsure as to the specifics, but no one can argue against NASA having an insane amount of data on hand. They also have a fair number of locations to which large amounts of data may need to be sent for various research purposes. They need it to be fast since very large quantities of data need to travel across the world and people are paid by the hour."
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762d05 | A.I. "was never shown what walking looked like" and yet "taught itself to walk" | [This animation of an AI "learning" to walk.]( URL_0 ) * What does it mean that the AI was "never shown what walking looks like". Wouldn't the programmers have to provide a finite number of possible configurations of parts, or simple limitations, which would effectively feed the AI the answer to "this is walking"? * What does it mean to "incentivise" AI? Is that an attempt to anthropomorphize the act of giving instruction? Is it actually an incentive for the AI, like a cookie is an incentive for a toddler? Or is it just a command? | Technology | explainlikeimfive | {
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"The programmers start by setting up an environment--some sort of basic physics engine, much like you might find in a modern game. Within this engine, they design the physical structure of the model that they want to walk--it gets arms and legs, with physical properties like strength and inertia. From there the AI's job is to take some information about the state of the model and use that to come up with how hard it should pull or push each joint. To say that the AI wasn't \"shown how to walk\" this means that the programmers didn't go in and say \"walking consists of moving legs back and forth, alternating, while swinging your arms back and forth.\" A traditional approach would start from some basic motion profile like this, then let the AI learn how to tweak that profile in response to what simulated robot senses. This AI was given no such starting point and it's likely that the first approaches looked more like seizures and first-time player of QWOP than anything remotely resembling walking. The incentives come into play as the AI learns. Many AI approaches consist of trying different things, measuring which ones performed best, then tweaking the best performing options. For this kind of approach you need some way to identify something as \"best.\" For these AIs this seems to have been a simple distance measurement. To see something similar done you should check out URL_0 . To draw parallels, this AI seeks to build a car with no idea what cars look like, with the incentive of traveling to the right on the screen. At first the guesses are horribly mangled garbage, but after a few generations they start to look remarkably car shaped and they start managing to cover an impressive distance.",
"> What does it mean that the AI was \"never shown what walking looks like\". There's a model with parts that are attached with some simulated physics. That constrains what the part can do. The AI program is in charge of providing the input--how will the parts move? At first, it's input is simply random. For example, the input to each leg may not be synchronized in any way. > What does it mean to \"incentivise\" AI? For each run, the program stores what it does and whether it fails or succeeds. (It probably stores how far it got to the end point, too, and how long it took.) The next time it runs, it repeats actions correlated with success and avoids actions correlated with failure. Over time, its actions become less random as, by chance, it finds successful things to do and keeps doing those. Note that movements not strongly tied to either success or failure stay mostly random, e.g. look at the flailing of the arms.",
"1. The AI was never given to goal of \"Learn to walk\". It was given an environment and a puppet to control with the goal of \"Get puppet over there\". The AI then eventually came up with walking as a propulsion method. 2. It was not given instructions on how to achieve the goal. It was shown what the current state is, what the possible interactions are (muscle contractions on the puppet) and what the goal is. The closer it gets to the goal, the better score it gets. So you could look at it this way - its instruction was to get the best score possible. And since getting closer to the goal increased the score, it was incentivised to get to the goal.",
"> Wouldn't the programmers have to provide a finite number of possible configurations of parts, or simple limitations, they don't need to possible provide configurations, just possible actions, the AI has to figure out how to combine the actions itself. Yes limitations on actions would be provided. > which would effectively feed the AI the answer to \"this is walking\"? No, there are many ways to try to get moving that are not walking, the AI was not rewarded based on how close to walking it moved, but how successfully it moved in general. If there is a more efficient way to move forward the AI could very well have found that instead of walking.",
"Remember this is a simulation. There is no true landscape. There is no creature running. The programmers wrote a program which created a landscape. They wrote a program to resemble a final creature. What liberties they took we do not know. Apparently the creature gets some sort of \"sight\" in that objects ahead can be detected so that eventually it could walk around objects. Now come the interesting part. The programmers designed some sort of mutation effect. The program generating the creature would change itself randomly. We do not know what parameters the designers allowed mutations on. But multiple variations of the original creature could be generated. The designers now had mutated creatures in a landscape. They ran innumerable iterations of mutated creatures. When random mutations in the program creating the creature produced one which could move that program as selected and preserved. Ir was reused as the creature basic program. More mutations were created. the ones which moved best were selected for. With millions, maybe billions or more, of iterations of this selection process the animation which walked the best was produced."
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762w7k | What prevents a penetration tester to simply not report a security weakness and then in the future uses it for his own unethical hacks? | Technology | explainlikeimfive | {
"a_id": [
"doawsxo"
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"text": [
"The short answer is morals and reputation. \"White Hat\" hackers make ridiculous amounts of money doing what they do because they have good reputations and skills. If it's ever shown that they didn't report an exploit that means they are either not good at what they do or they're dishonest. Both ideas would kill their business quick."
],
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|
764jql | How do cell phone cameras adjust focus without any moving parts? | Technology | explainlikeimfive | {
"a_id": [
"dob782d"
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"text": [
"They do have moving parts. A really, *really* tiny linear electric motor moves the lens forward and backward. URL_0"
],
"score": [
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"text_urls": [
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"https://www.westfloridacomponents.com/blog/how-does-a-smartphone-camera-autofocus/"
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765u0l | Why is it hard to implement a standard volume across various mediums like radio and television? | Differences in recording equipment and technology, conversion from analog to digital signals, processing/remastering and the disparity between mediums (radio vs. television vs. podcasts, etc.) lends itself to making a standard hard to define. Here we are, well into the 21st century and even within the same podcast I have to turn the volume down between commercials and the "show." Television commercials consistently vary in volume from the main program and don't get me started on radio. With everything going digital, is there a way to form a standard volume through a "universally accepted standard" or "universal protocol"? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Hey there I work for 2 major broadcasting companies in Canada, and in one (where I currently am, on a 10 hour shift) I am the person who ingests, quality checks, and approves all the commercials we air across all of our 7 channels. So in Canada and the US, there are laws dictating how loud content is allowed to be. This includes both the actual show you are watching/listening too, and the commercials that are in between. Basically, the government says \"the maximum output allowed by anyone is _______\" and we all have to abide by that. My companies policy is that commercials must be withing -24 +/-2 LKFS (LKFS is a measurement of loudness). So every night I get a sheet of 40-150 commercials that need to be ingested, and I adjust their levels to be within this range. So the best way to think about this is that the commercials themselves are not what are loud. Everything else is quiet. A standard has been set for everything across the entire network, and commercials are always safely within the margins. However, since the content you are actually trying to watch is dynamic, with loud and quiet spots, you likely are listening to it slightly louder than that standard would want you to so its easier for you to hear dialogue, or quiet parts in the show/music. This is especially noticeable if you constantly ride the volume level on your stereo or television when something loud happens. Since commercials generally want to be heard easily, and typically don't have dynamics, they seem to be much louder than everything else. Side Note: There are ways that commercials can actually be slightly louder than others. Since the volume standard we use is an average over the entire spot, a quiet commercial with a loud portion at the end or a commercial of just straight dialogue vs dialogue over music can come out with different averages. Generally I adjust the volume of spots like this that seem super loud so they are more in line with the standard. Hope this helps",
"It's not that it's hard it's because it's on purpose. Commercials come in louder because the advertisers want to ingrain their product in your mind and make sure you hear loud and clear what they are selling.",
"Posted in response to someone else’s answer but for OP I’m posting again for an answer. It’s not that the commercial is louder, it’s that the commercial is set to the highest volume point of the show, so while the show changes volume to add drama by raising it for shouting scenes and lowering it for somber scenes, the commercials don’t change along with the context of the show. This is the real reason commercials seem louder than the show.",
"Our ear judges loudness as an average of loudness over time. A dramatic tv program will naturally have peaks and troughs in volume as different situations unfold (building tension with silence before a big scare in a horror movie for example). Advertisements are “compressed” ie the loudest sounds are made quieter, the quieter sounds are made louder, and the general volume of everything is increased and pushed to the max. This is because they want your attention. Generally you’ll find that radio sound levels are pretty regular as they’re made to be heard over the sound of your car, and no station wants to be quieter than the rest so they all pump it up to the max. You’ll also notice no difference in volume when the song goes from acoustic intro to anthemic Rock chorus. As for podcasts, even some very popular ones have pretty sketchy audio production but that’s generally improved over the last few years. In my opinion, unskippable ads will probably start infiltrating soon and they will become more monetised, in which case they’ll fall into line with radio standards."
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767kyu | How does a radio station send metadata like song name to my car's radio? | I was driving in my car, and for the first time noticed that the name of the current song on the radio was scrolling across the little LCD screen, and I wondered how that metadata works from the radio station's perspective. | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Modulation became more efficient, which opened up space in the guard bands to transmit digital information on a sub carrier. Edit : okay imagine that while recording the song the radio station was tapping out a special code in the background of the song that only your car radio could hear. That code is the meta data.",
"You're seeing the effects of the Radio Data System (RDS). Basically the radio stations encode simple data as a series of a high-frequency (inaudible to humans) tones which a decoder in your radio can detect and decode. RDS is used for other things too like traffic information (many dedicated GPS units can tap into this) and clock synchronization."
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76cybb | Why, especially in older software, does software load times not decrease significantly with a faster SSD? | Upgrade computer storage that is 100 times faster than your old one, but that program barely opens or loads any faster. Why? | Technology | explainlikeimfive | {
"a_id": [
"doczpjt",
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"text": [
"The SSD only speeds up one aspect: retrieving the code storage. Starting a program often involves other steps -- computations that are limited by the CPU, or network communications, unaffected by the SSD.",
"I would have to guess probably the efficiency of the code itself. I wrote a program that converts images to black and white in real time (shows the conversion on screen) and before I streamlined the code it didn't matter how fast the pc was it took the same length of time to process basically. once i streamlined it then you could see a difference in speed on my faster pcs. I could be wrong tho"
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76f16z | What does it mean when a game or movie has been "remastered"? | Technology | explainlikeimfive | {
"a_id": [
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"When a movie is shot, it used to be shot on a roll of film, in high quality. That roll of film is called the Master. Maybe you'll remember cassette tapes, they used to have a box for you to tick for Master and Copy. When you copy the master onto a new medium, or simply onto a similar piece of film, it is very likely that some of that quality is lost. Furthermore, the master is super high quality, but hard to work with. So, for colour correction, editing, etc., it's common to downsample the master to what the end result will be. For example, if you're releasing the movie on DVD you'll make it 1080p, so no need to keep the 8k resolution you shot it in, or editing will be so much slower. However, there comes a time when technology advances, and people move from 1080p to 4k, for example, and your movie starts to look dated and low-quality. But your source footage is much higher quality, so you can take it again, put it through the whole process again, and create a higher quality version of the movie for the fans to enjoy. Thing is, it's not as easy as taking the film and converting it to what you want, since you need to once again edit it and so on, since only the source footage is at that high res. For games it's similar, for example they move the maps and game logic to a newer engine, and they create bigger textures and more detailed models, which might already exist, but which were simplified or shrunk in resolution in order to help the game run smoothly."
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76gida | Why do digital time displays, such as a microwave or oven, seem to flash constantly on video? | Technology | explainlikeimfive | {
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"Those LED displays save money by sharing the wires between segments. So you'll have a 7 segment display and it has 7 wires each connected to one segment for all digits, and then 4 wires that are connected to all segments but one digit. They might have a few extra wires for the other status bits and such. But this gets them 11 wires for a 4 digit display, if every segment was individually connected you'd need the ground plus one for every segment (29 total wires). Anyways, because it's wires that way you have to light up only one digit at a time, if you light up multiple digits at once you can't make them show different numbers. So what's done instead is it quickly cycles through digits, lighting up one digit them lighting up the next with a different number. It repeats this so fast that you can't see it. However cameras take short pictures, and it might catch only one digit lit up per frame. They do this at a set rate, and it has the effect of making them appear to flash at a rate slower than the camera (so a 4 digit display might appear to flash at a quarter the speed of the camera because only one digit is shown per frame).",
"It's just a refresh time offset. Lets say your microwave display is refreshed 1/20 second and you camera is refreshed 1/60. You're camera catch all 3X more image than your microwave can display so it catches the \"dead\" frame where nothing is displayed on you microwave. Your microwave don't need to refresh it's screen as often as any video capture device since it's made for human to see time. Even if it's 1/3 of a second too late in the refresh process, the human don't care. However, if a video on youtube is 1/3 late, you'll see because there's a lot more moving part than on your microwave screen.",
"A digital time display has lots of individual elements. A single digit needs 7 elements, and with 4 digits you would need 28. If you wanted to individually control each element, you would need 28 separate outputs. This costs money. To make things cheaper, you can use 7 outputs connected in common to all the digits, and 4 outputs to select which digit to turn on. Instead of turning them all at once, you can keep flashing individual digits one after another. If you do it fast enough the human eye won't normally notice flashing, and it will be as if they're lit continuously. Cameras can have very short exposure time, during which time they see only one or some of the digits being lit up. A video camera may record at 30 frames per second, but that doesn't mean it captures light for 1/30 of a second for one frame followed by 1/30 of a second for the next frame. It only needs to capture light long enough to capture enough light, and so it might capture for 1/200 of a second for each frame. Then you get interesting effects due to the combination of the digits flashing and the camera only capturing light for short periods."
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76htpp | What is the difference between a GPU and a CPU? Which would yield higher gaming performance? | I'm trying to upgrade my computer for the first time ever. It was a prebuilt one that is seven years old now. I'd like to think I am knowledgeable in the subject but I'm really not. I don't have a lot of money so if I were to buy one thing that would help me catch up to play better looking games I need to understand the difference between a CPU and GPU. I thought a graphics card was all I needed but I see talk of CPU increasing FPS. | Technology | explainlikeimfive | {
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"Both the CPU and GPU are used to process a \"frame\" of a game. Broadly speaking, the CPU works out where all the objects in the game are by taking your input, simulating physics, running game logic and so on. It then passes that information onto the GPU so it can do all the graphics processing required to actually draw all the 3d models onto the screen, with the right textures, with the right lighting and so on. These two things happen in parallel. Once the GPU is doing its thing, the CPU can start work on getting the data for the next frame ready. Then it has to wait until the GPU has finished the current frame before giving it the data for the next one. This means each frame is only as slow as the slowest component. If the GPU is slow, the CPU will have to wait around doing nothing useful until the GPU is ready. If the CPU is slow, the GPU will be waiting around for the CPU to give it the next frame's data. So both the CPU and GPU are important to getting good performance. But if you have a rubbish CPU, getting a faster GPU isn't going to give you better FPS. However, these days the bottleneck is usually the GPU. Games usually have more work for the GPU to do than the CPU (especially if you run at a high resolution), so usually upgrading the GPU will improve performance, but upgrading the CPU might not give much of a performance boost because your system is still limited by the GPU. It depends on the game though. But if your CPU is quite slow, and it is the bottleneck, then yes upgrading your CPU will improve performance.",
"GPU is what makes your graphics pretty. CPU is what makes your computer think better and faster. CPUs don’t really need to be upgraded that often. I have a gaming desktop from 2012 and my CPU works fine on max ultra settings for most games. However, it is the GPU which I had to upgrade since then. CPU is mostly notable for games which require a lot of computation but most games just make the GPU do all the work. Get a decently priced i7 (no need to go crazy) and get a 1080 and you’ll be set for another 5 years."
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76hztw | What does the big machine for (i believe) asthma do? | So just to clarify, its this big machine thing where you have the little like drips of liquid that you put into the machine and then have this mask thing hooked up to your mouth. (details may differ from actual machine as i havn’t touched my machine in years and technology is advancing quite quickly) | Technology | explainlikeimfive | {
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"If you're talking about a Nebulizer, they vaporize medication into a mist that can be easily breathed into the lungs. Yes, the machines used to be large unwieldy things. But you are correct in that technology has improved quite a bit. My sister uses one that is only a bit larger than an inhaler."
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76k17e | How can HDDs and SSDs delete data faster than they can write? | Technology | explainlikeimfive | {
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"When you delete something, you're not actually removing it from the drive. Instead, the computer is just telling itself to recognize the space as free and writable. Once you start saving new documents, downloading new music, etc. the \"deleted files\" (which are still sitting on the drive) will begin to be overwritten.",
"When you write data to a hard drive, two things happen: the data is written to some sector of the hard drive, and the location of that sector is stored in a table that tells the computer which sector to look at for each file. When you delete a file, the location data is removed from the table. There's no need to actually delete the data from the sector; the computer will treat that sector as free space as long as the location table says no data is stored there. By the way, this is why lost data can sometimes be restored. As long as the sector where a deleted file was stored hasn't been overwritten with a new file since you deleted it, you can scan a hard drive sector by sector and read off some of the data that was stored there."
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76kpmx | how did humans even create computers ? | Technology | explainlikeimfive | {
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"Computers weren't created all at once. It took baby steps and new technologies, like microtransitors, to be invented to progress them to where they are today.",
"The history of computers is a whole topic in itself, and the first \"computers\" were more like calculators e.g. Babbage's [Difference Engine] ( URL_2 ) or the various [Tabulating Machines] ( URL_1 ). The idea of a program that can be changed goes back to the punched cards used in the [Jacquard loom] ( URL_0 ). Fully electronic computers go back to the 1940s, with a lot of pioneering work in the UK, driven by the war effort.",
"We started with the abacus, which is an extremely manual computer. Then we moved on to analog computers -- slide rules being a simple example. We also had Babbage's machine as a model (or at least inspiration) of how to implement mathematical operations in gears. Perhaps inspired by that, there came a series of tabulating machines and [mechanical calculators]( URL_1 ). Punchcards came about as a means to enter data into these tabulating machines efficiently and accurately. We eventually figured out how to use a transistor to implement certain logical operations, then how to use logical operations to implement math. Then we came up with ways of storing data that we could read electronically. One technique involved a phosphor and a light sensor in a tube. You'd light up the phosphor, which would stay lit for a while. Then the light sensor would detect if the phosphor was on and emit a current back to the phosphor, to keep it on. To set that bit of memory to 0, you'd either block current to the phosphor, or you'd move something to block the light. There was a similar type of memory involving tubes of mercury. [Core memory]( URL_0 ) was a later advancement and a lot more reliable. This all let us make electronic, digital equipment that would do a specific thing. You'd have a computer, but it would be wired for one task. You'd have a row of switches to change its input, and a bunch of lights to read its output, but that's it. The von Neumann architecture brought us from that world into something like modern computing: the computer was wired for a specific thing, and that thing was reading a program from memory and executing it. This produced a distinction between programming and electrical engineering. It also meant that one very expensive machine could do the work of many slightly less expensive machines. The next giant advancement was printing transistors in silicon, and that's where we are today."
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76kr62 | Why does putting receipt paper over a debit card make it work when it wouldn't scan otherwise? | Technology | explainlikeimfive | {
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"Oh boy, I can try to explain it to an adult but even that is somewhat difficult, a five year old is a lot harder. Magnetic strips contain information that is stored in small magnetized particles which the card reader detects. These particles are put into specific sections of the strip where the card reader looks for them. Over time as cards are rubbed on the inside of wallets and other things, some of those magnetic particles move into sections of the strip they don’t belong. This can cause the card to misread however these tiny particles aren’t very strong cause there’s only a few rogue particles. So when the card reader is in direct contact with the magnetic strip it can read these rogue particles but by putting receipt paper it moves the card further from the card reader and those rogue particles that got smeared around are no longer read by the card reader cause their signal is no longer close enough to be read . This is probably a terrible explanation Imagine you have 5 groups of people. Each group had 50 people. Each group wears a specific color T-shirt. Now clearly segregate these groups. One group of blue shirt, one of red shirts, yellow shirts, green shirts, and brown shirts. If you stand within 10 feet of these people you can clearly see each individual in the group wearing their color. Now take one person from the blue shirts and put them in the yellow shirt section. From 10 feet away you can clearly see the blue shirt guy in the yellow section. the blue shirt section even though now only has 49 blue shirts you can still see that it’s a blue group. Now back up 100 feet and you can’t see the one blue shirt in the yellow section very well but you can clearly still see that the shirt group is yellow. That’s kind of how it works when a “blue shirt” magnetic particle gets rubbed into a “yellow shirt” section of the credit card. Up close the reader can detect it and causes an error, but move the card away from the reader using a layer of paper or plastic, and the reader can’t detect that one wrong blue particle cause to the readers eyes it can only see the yellow at that distance"
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76nfe1 | How do tape recorders adjust for the differences in spool sizes? | I just started watching Mindhunter on Netflix today (really good show btw). The opening title sequence shows an old tape recorder being nicely setup and turned on. Once the recorder turns on I immediately noticed that the winding spool is spinning faster than the unwinding one. Pretty obvious actually (the smaller spool has a smaller circumference so it has to spin faster) but I never really thought about it! Taking it further though you realize that as the tape continues to be wound the circumferences is constantly changing on each spool. So since the recorder needs to maintain a constant speed of the tape across the record head, how does it adjust for these changes? | Technology | explainlikeimfive | {
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"The speed of the tape isn't controlled by the speed that the reels turn, it's the other way around. Part of the tape path, usually just after the heads, is a cylindrical drive called the [capstan]( URL_0 ), and a pinch roller to hold the tape against the capstan. The capstan turns at a constant speed and *that* is what determines how fast the tape moves. The feed reel and the take-up reel turn at whatever speed it takes to feed/take up the tape at the speed determined by the capstan.",
"The spools don't actually pull the tape past the record head! That job is done by a third rotating element called the [capstan]( URL_0 ) which, with the help of the pinch roller, grips the tape itself, and pulls it through at a constant speed. The motor drives the take-up spool with a friction clutch, so it provides enough tension to take up the tape smoothly no matter what diameter the tape spool is. This is why cassette tapes have those extra holes near the bottom: the capstan pokes through them to get behind the tape."
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76q9rq | Telephone/Transmission/Utility Poles. What are the different components? | Driving to work and the thought crossed my mind. Besides the transformers what are all the other components on it? What all is carried data wise? Whats the ordering of cables? What are all the various boxes on it? Thanks in advance | Technology | explainlikeimfive | {
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"Can answer for Transmission towers at least. [I'll use this picture as a reference.]( URL_0 ) The uppermost single wire running across the top of the tower is a grounding wire, meant to keep towers at the same electric potential and to protect the wires below from lightning. There are six sets of \"live\" wires: three on each side of the tower. Each set of 3 is a single \"line\", meaning this tower (and most towers) carry 2 separate lines. Each individual bundle is a single phase, with the 3 bundles together making the single three-phase \"line\". Power is almost always transmitted and distributed in three phase form, but most individual houses will only receive a single phase (as household appliances don't need three phases to operate). I don't know where the tower in the picture is, but for the UK (where I am) the fact that each single-phase bundle of wires has 4 individual wires suggests it is most likely a 400kV line (this is a rule of thumb, though). The ridged arms that hold the wires, dangling below the steel arms of the tower itself, are for insulating purposes: they keep the wires far enough away from the steel tower to prevent the electricity getting onto the steel tower. They're usually made of porcelain and the ridges alternate in diameter so that any water that drips off one ridge misses the next ridge (as its smaller) and lands 2 ridges down. This is to stop electricity jumping (called \"arcing\") up raindrops or \"tracking\" up a solid stream, as the distance becomes too great. The higher the voltage, the larger these porcelain arms are. You can see at the top and bottom of the porcelain arms that there's \"horn\"-type spikes at the top, and \"handle\"-type metal poles at the bottom. These are \"arcing horns\" and act as a sort of pressure relief device: if something were to go badly wrong and the voltage on the wires were to go up enormously (for example if the top grounding wire failed and the lightning hit a live wire) these arcing horns are close enough together that electricity can jump (\"arc\" or \"flash over\") between them, with the top \"horn\"-type spikes grounded to ensure the electric energy is safely dissipated afterwards. This is to protect the porcelain insulating arms, because if they were to explode (as they would if subjected to such a voltage) they can act like fragmentation grenades: they shatter into small, sharp shards that will fly out at very high speeds, potentially harming anyone or anything nearby. You can see, on the wires, just after they connect to the porcelain arms, that each individual wire has a little toggle thing attached to it. These are anti-vibration devices that are designed to counter-vibrate if the wire starts to vibrate, in order to cancel everything out and keep the wire still. The barbed wire at the bottom is to stop people climbing up and the little sign normally denotes the voltage, line ID, and tower ID. I think that covers all of it. Is this what you were asking, or are you asking more generally about how the whole system works?",
"Utility employee here. For utility poles, lines at the top are the electrical, lower down are cable, telephone, etc. The idea here is that those cable workers won't get zapped so we keep their stuff further down. If you imagine a pole you could have the following from highest to lowest on the pole: * Primary electric (4-15 kV) * Secondary electric (115/230 volts) * Traffic signal wiring (if applicable) * CATV cable (broadband for cable network distribution) * Telephone What you'll start seeing soon is 5G. These are small cells that cover just 1,000 feet or so, compared to the cell towers you're used to seeing. These may be at the top of poles like an antenna, or part of a box attached elsewhere.",
"**Note 1:** The specific rules vary regionally, so some things here may be different where you are. **Note 2:** I am not a linesman or a city engineer, my terms may be different than the official / industry terms. Please let me know if there are better words or if I'm saying something wrong! Utility poles typically carry power and/or data - copper telephone wires, fiber optic data lines, coaxial cable TV and internet. Most often power and data can be on the same pole, but in some cases you may have them separate - phone lines on one side of the road, power lines on the other. This is because they were put up at different times or by companies that don't have an agreement to share space on the same pole. On a pole that carries power, the lines go from least-to-most dangerous as you go up the pole. A large, busy pole might look like this: * Branch data (line that goes into your house) * Neighborhood data (combined lines that run locally) * Trunk data (bigger, combined lines that run around the city) * Ground wire * Branch power (power line that goes to your house) * Transformer (takes higher voltage and makes it house-friendly) * Grid-section power (provides power to the transformer, feeds your block) * High-tension power (higher voltage than grid-section power, may feed a factory area or several grid-sections) **Regarding boxes on poles**, there are many different kinds, but the most common ones you see are \"make higher voltages lower\", called transformers, and \"split cables from many to few\", typically called distribution boxes or cable trays. Transformers are the big, normally tube-shaped things you see every few poles in an area with houses. You may also see bigger ones by shops and factories, and *really* big ones by heavy industrial areas. Transformers take higher voltages that come in from the power company and turn them into the power that comes from your outlets in the house. Distribution boxes just let the phone, cable, or internet company split out and organize their lines from the big lines that come in from the central office to the street-sized and individual lines that run to your house."
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76soxd | How companies track your browsing history. | For some background info, I'm at Uni and I was browsing through some products on my phone in my room. I went to the Computer lab and logged in. I found the same products i was looking at. Nothing NSFW i was just wondering how exactly they do that. I was on two different accounts. | Technology | explainlikeimfive | {
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"The more relevant an ad is, the more likely you are to click on it. Relevance and high quality clicks are encouraged and prioritized by ad networks like Google and Facebook, and result in cheaper costs to the advertiser and a higher likelihood of the user completing a specified action on the website (called a conversion) like a purchase or a form completion. Advertising networks and e-commerce platforms provide tracking codes to advertisers to install on our clients' websites. This allows me to track actions like a website session, pages visited, actions completed on the website (like an item added to a cart, or an abandoned cart), etc. When you visit the website, tracking data is added to your web browser or associated with your account if you're logged in. Based on your activity on the website, which is anonymously shared with my advertising account, I can then show you, an interested user, ads relevant to what you were looking at. In terms of cross-device tracking, all that data is gathered based on the accounts you're using. If you're logged into Google Chrome on your phone and look at an item on Amazon, that data is logged and associated with you (again, totally anonymously to me). Based on that, I can then set my ads up to show you similar items on other devices where you're logged in with that account. I wouldn't be able to say specifically how that happened to you in your example, but essentially it's you and your actions on both devices being associated with each other through whatever service, so the advertiser can hit you with ads."
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76v2q2 | is the computer ram's lifespan affected by the load | I run virtual machine, and the ram load is always at around 90%. Will this shorten the ram lifespan? | Technology | explainlikeimfive | {
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"No. First even if your computer shows 90% usage your OS will really be attempting to use 100% of your ram all the time, the other 10% is being silently used for things like caching files and file system data. Second the way that DRAM works means that every bit of ram is being exercised many times a second regardless of whether your OS considers it \"allocated\" - unlike static ram (SRAM or the cache inside the processor) DRAM is based around tiny capacitors that either contain a charge (1) or don't (0). These capacitors will naturally loose their charge in only a fraction of second if left on their own so they need to constantly be refreshed. During a refresh every bit in ram is read internally (the CPU isn't involved, it's all done inside the RAM chip) and if it's a 1 meaning there was charge in that cell then it is fully recharged."
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76wxin | Why do android phones get slower over time even after a factory reset? | Often the common complaint would be of cache, data or new updated apps, but I've seen them get slower than a brand new phone even without any updated apps. | Technology | explainlikeimfive | {
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"This is just speculation tbh. Over time, the same applications on your phone consume more resources. This is because the rate technology improves is swift, and application devs are constantly keeping up. So say an app is currently built to run well on a phone with 1GB RAM. When phones with 2GB RAM become the norm, app devs feel comfortable giving their app a larger footprint on available resources. But your phone still has 1GB. And the app and the OS both have progressed to being comfortable using more resources than before. Hence the difference in performance. Edit: Apparently this has been asked before and the answer is flash memory degradation"
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76xntl | Do larger camera sensor pixels capture more light, making the image brighter? | Actually, while thinking of this question, I suddenly thought of rain gauges, where the size of the gauge doesn't matter when measuring rainfall... does this apply to pixels as well? Or does larger pixels mean brighter images? | Technology | explainlikeimfive | {
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"Larger pixels mean more light. Smaller pixels mean more amplification is required to achieve the same brightness and the result is noisier images. Both the sensor and the amplification electronics generate random noise and having a strong signal due to more light minimise the impact of the noise. That's one of the reasons pros still use big cameras with large sensors, often 24 & times;36 & #8239;mm. (The other big reason is that large sensors mean a shallow depth of field, so you can have everything except the subject out of focus.) This is an argument for having lower resolution sensors, though to an extent it's possible to average neighbouring pixels as another way to reduce noise, albeit at the cost of resolution. Larger pixels also tend to make better use of right reaching the sensor since there are fewer boundaries between the pixels so less light is wasted."
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76zfcd | Why nearsighted people need glasses to see objects "far away" in virtual reality, even though the screen is very close. | I've wondered this ever since I got my vive. I'd think I wouldn't need to wear my glasses since the screen is right up to my face. | Technology | explainlikeimfive | {
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"text": [
"Because the headset uses lenses to place the screen at an optical distance that is much further away. You'll notice that you don't have to focus your eyes in the same way as if you put your phone screen right in front of your face."
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76zoh9 | Why is closing a crashed game on PC so difficult? | Technology | explainlikeimfive | {
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"Because you're telling the OS \"send this game a message telling it to shut down.\" If the game is responsive that's not a problem, the game hears the message and turns itself off. If the game crashed or in any other way is unresponsive you're talking to deaf ears. The game can't hear the message and can't turn itself off, it cannot respond to anything the OS is telling it to do. At this point the OS must kill the process (usually via the task manager) by depriving it of its resources and forcefully killing off the game.",
"Former game developer here, u/Mr-Magnus has the gist of it. Key commands are sent through a hierarchy, so the active window gets the first chance to react to it, then on down to the OS. If the game is hung, it's going to get a queue of messages it's just not processing, and it's going to take a bit for other mechanisms to take action, because Windows is going to try to play nice and let the program finish what it's doing before assuming something's gone wrong. Further, when your game runs in full-screen mode, the video subsystem gets to make certain assumptions and take advantage of the video hardware in ways it can't do when the game is windowed, for better performance. Your game running in a maximized window is not the same thing as running full-screen. Switching out of that context is a huge pain in the ass, and it goes easier when the program is responsive and can voluntarily leave full screen mode to minimize."
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7708v8 | How is this new forged carbon stuff stronger than traditional carbon fiber? | To me, it seems like the consistent, alternating layers of traditional carbon fiber would be stronger than the much more randomly oriented and spaced fibers of forged carbon. | Technology | explainlikeimfive | {
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"Without going and reading about this 'stronger' typically means a specfic type of strength - how hard you have to pull on both ends to tear it. In which case an obvious example is plastic. Plastic polymers look like a heap of tangled worms at an atomic level, and this gives them much more of a specific type of strength than could be obtained by lining them all up. It's also responsible for the ability to bend back into the original strength, and I would suspect this forged carbon also has shape memory. In contrast -edit- graphite is composed of parallel sheets of perfectly aligned carbon atoms and it's very easy to sheer off a chip or cut it in half because the sheets of carbon don't attract each other as much as they attract atoms in the same sheet."
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770ab6 | Why does JSON seem to be replacing XML? | Technology | explainlikeimfive | {
"a_id": [
"doi1ks3",
"dohzm64",
"doi3jmh"
],
"text": [
"Xml is very verbose and requires more data to be transmitted. Specifically the ending tags. Xml: < Person > < handle > krystar78 < /name > < redditID > 12345 < /redditID > < /person > Json: { handle: 'krystar78', redditID:12345 }",
"XML introduces a lot more complexity than most people need. JSON more closely resembles how API programmers think, and the very light complexity of the data they usually care about.",
"XML is a great thing if you want to represent data with a complex structure and have a schema associated. You can validate the syntax as well as the structure, and the elements. It is suited to represent documents in a wider ecosystem. The cost is complexity of the document itself and the associated parsers. JSON focuses in representing a few predefined types of values, omitting much of the complexity of XML. JSON alone is less portable outside the original ecosystem, due the lack of document semantics, and lacks proper validation and description (ignoring JSON LD). And frequently, this is just enough for many applications."
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771a2a | Why does it take 3-5 days for an email service to unsubscribe me from their list? | It just seems like this should be able to process within a few minutes and not a few days. | Technology | explainlikeimfive | {
"a_id": [
"doi8235"
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"text": [
"It doesn't, they're just covering their asses in case there was an email being sent to you by some server somewhere in the pipeline. Unsubscribe requests filter into lists gradually."
],
"score": [
3
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772mtd | What's the difference between a 32 bit operating system and a 64 bit? | Technology | explainlikeimfive | {
"a_id": [
"doindof"
],
"text": [
"The difference is 32 bits... bah-da-boom.. Seriously, you are limited to 4G of RAM with only 32 bit OS (address limit 'cause you only have 32 bits to use). This also translates into how much info you can pass through the computer - like drinking a slurpy through a narrow straw. With 64 bits you get more memory to address and more info (or banana flavored slurpy) through your straw."
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3
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|
773gfx | Why can't computers use storage devices as RAM? | Technology | explainlikeimfive | {
"a_id": [
"doirbax"
],
"text": [
"They can and do, it's called a swap space(unix)/paging file(windows). It can't be the main RAM source though due to speed limitations."
],
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3
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775e0h | How do programs that are not for commercial use detect that they are in fact being used for commercial purposes? | Technology | explainlikeimfive | {
"a_id": [
"doj5qbx",
"doj69wd",
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"text": [
"Generally they don't, in most cases it's a legal rather than technical restriction. If you violate the restriction, you would lose your legal access to the program and possibly (depending on where the restriction comes from, the laws of the particular jurisdiction, etc) open yourself up to getting sued for damages, and that's generally sufficient to keep people from misusing the program.",
"TeamViewer has a limit on the number of different computers you connect to - above a certain limit they claim it's no longer personal use. Most other programs don't know, but if their lobby group audits a company and finds their software running, or their lobby group's advertising convinces an employee to dob in their employer, then they demand payment.",
"It depends on the program. Some programs impose arbitrary limits that would be unlikely to effect personal use (for example, limiting the size of an outputted file, its resolution or duration), but would with commercial use others use watermarking to 'spoil' the files on non commercial/student versions A lot though, simply rely on honesty, or only offering differing levels of support and access to updates."
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|
776kvr | Why can't we remove salt from seawater to solve water shortages? | Technology | explainlikeimfive | {
"a_id": [
"dojdft1",
"dojdgix",
"dojdgk6",
"dojdkg6"
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"text": [
"we can, its called desalinization. huge pumps force water at super high pressures through special filters. Its very energy intensive though, and the plant is expensive to build, so typically, whenever there is a drought, it comes up, but then the drought ends before the project ramps up so it gets shelved.",
"We can but it requires a lot of energy which makes it expensive and water shortages usually happen in poorer area. The problem is not a matter of fresh water but of distribution.",
"There are desalination plants throughout the world. Like everythibg, it's a matter of cost- if other methods are cheaper those plants aren't going to be developed.",
"It's possible to do (it's called desalination), but it's an expensive process, doesn't generate enough water to fully supply a city, and it generates potentially harmful brine that is released back into the sea. San Diego fairly recently built a very large and expensive desalination plant. It cost over $1 billion, but it only supplies the city with 7% of the city's water."
],
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|
776v4d | How does clearing browser cache fix a lot of website issues? | Technology | explainlikeimfive | {
"a_id": [
"dojhexd"
],
"text": [
"In the case of a web browser, sometimes temp files and cookies are not current, or even become corrupted. Either way, if changes were made in the browser when trying to load, if the browser is attempting to use what is cached and it is conflicting with what the website currently has, then it can load screwy or not load at all. So clearing it forces the the browser to load it as if it were visiting the page for the first time. Also to note, sites that use a page count, such as newspapers who allow a limited number of articles to be read without a subscription, use cookies and temp files to show that this browser/pc has read x-number of articles, which would cause it to load that annoying screen prompting you to log in or subscribe. Clearing the cookies removes that reference point."
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13
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|
777pyd | how does the Nintendo gun from Duck Hunt work? | Technology | explainlikeimfive | {
"a_id": [
"dojni94",
"dojn28d",
"dojpwne"
],
"text": [
"Think of the gun as a camera that is zoomed in all the way, and when you pull the trigger it turns the screen black for an instant, except for targets which are replaced with bright blocks, and then it takes the picture. If it captures light when it triggers, then it registers a hit. If it captures dark, then it's a miss. CRT displays are actually a single dot of electrons that strike the back of the picture tube, and are converted by a phosphor into a dot of light. In order to make that dot show an entire picture on screen, it has to be moved around rapidly, faster than the eye can see, to draw an image in. It does this by sweeping the dot across the display from top to bottom, left to right 60 times a second (59.97 times if you allow for the slight pauses as it resets) So if you can calculate the exact amount of time it takes this image to be drawn, then you can calculate the position of things on the screen. The NES and Sega Master system guns worked similarly to this by using a light sensor built into the gun, and a timer that kicked off the moment the trigger was squeezed. When you pull the trigger, the screen empties and becomes black, and that moving CRT dot lights up when it gets to the area where the duck, or whatever target you'e aiming at happens to be. Simultaneously, the gun waits a few milliseconds and then takes a measurement of the light level it's pointed at. If you're pointing at the target, the gun will see light at the exact moment the CRT is drawing the bright square where the target was, and it registers a hit. If you were aiming incorrectly, then the gun will see only darkness during that small window of time when it's measuring. This is why the screen appears to flash a split second, each time the trigger is pulled. If you could slow it down, you'd see the screen go black, and white boxes placed where the targets were, the gun measures the brightness of what it's aimed at, and then the screen goes back to normal.",
"The gun is a light detector with a long tube in front of it (so it can only detect light in a small area). When you squeezed the trigger, the screen would flash one frame (which is short enough that viewers can't consciously see it) that was black except for a small lit square where the target was. If the gun detected the light from the square, the gun would send the \"hit\" message to the system, and if it didn't it would send the \"miss\" message. That's why they don't work very well with LCD screens, which have a small processing delay, so the single frame isn't on the screen when the gun is attempting to detect it.",
"Others have given the technical answer, I'll give the fun one. Want to get a perfect score? Point the gun at a light bulb instead of the TV."
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|
777vni | what’s the fundamental difference between a CPU and A NPU? | Technology | explainlikeimfive | {
"a_id": [
"dojrkrm"
],
"text": [
"Software developer here, A CPU has a fixed set of operations it can perform - there's physical circuitry for adding integers, for multiplying integers, for loading and storing, for shifting binary bits, etc. Each operation is enumerated, and a sequence of these enumerations is what we call a program. Data is read into and out of the CPU through a physical input/output interface called a register, which the CPU can have many - some serve a specific purpose, some just for instructions, some for different types of data, some are output only. Many CPUs have memory on the chip, what we call cache. And many have multiple \"cores\", or clusters of these circuits, so you effectively get multiple CPUs on a single chip. An NPU is *nothing like that*. They *don't have* fixed sets of operations, you don't feed it a sequence of instructions. It doesn't have something like registers, though it does have input and output mechanisms. It doesn't have cache, and it doesn't access memory the same way a CPU does. A CPU and GPU are designed for high levels of precision when it comes to decimal numbers, using 32, 64, 128, and in some cases 256 bits. When simulating neural nets, the notion of *data* or *values* kind of goes out the door; common designs use 16 or 8 bits, and IBM has a prototype that doesn't store numeric values at all - their notion of data are well timed electrical pulses, harkening back to delay-line memory of the 50s and 60s. Programming for these things consists of describing how the simulated neurons interconnect to form a network. There may be *some* ability to dictate how they operate, and some ability to observe their state, but really it's just give the network some input and read off the output. The purpose for these new class of processor is that they're really starting to see practical application, and you can run more neurons on one of these dedicated pieces of hardware than you can simulate in software on the worlds most powerful super computers."
],
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|
778416 | Why does turning on airplane mode and turning it back off help your phone reestablish a connection in an otherwise bad area for cell reception? | Technology | explainlikeimfive | {
"a_id": [
"dojq7xm"
],
"text": [
"Phones establish linkages to specific cell towers and there's a cell tower 'handoff' when you move from one cell to another. What usually happens in this circumstance is that the handoff wasn't completed or was done improperly due to the bad reception, so your phone is still trying to connect to the old tower and getting awful throughput (3G or lower). Turning airplane mode on and off resets this fresh and causes your phone to simply look for the closest local cell to connect to. Usually your phone will eventually give up trying to contact the old tower and establish a connection to the new tower, but this manual reset will do it faster."
],
"score": [
7
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|
779em0 | Why do police/fire radios sound so staticky? How do these departments that rely on radio communications understand each other? | Technology | explainlikeimfive | {
"a_id": [
"dok557i",
"doklkxe"
],
"text": [
"Cop here: The main reason is that we develop \"radio ear\". Basically we get used to the static, codes, shorthand, etc. It takes awhile and is something that Rookies have to overcome. In the academy we were encouraged to listen to the radio as much as possible. It's very much a learned skill. Another thing is that if you're listening to scanners, they're usually much worse quality than the actual radios are.",
"Audio quality isn’t the main priority. Connectivity is. Meaning if an officer is three floors below street level in a concrete parking structure he can still send/receive. An officer at dispatch can reach the dive team on a lake. It’s all about dependability and connectivity."
],
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77btix | It seems like people are much more familiar with bytes rather than bits because we use them for data storage. Is there a push to use bytes to classify network speeds (i.e. 1MBps instead of 8Mbps), as opposed to bits? | Technology | explainlikeimfive | {
"a_id": [
"doktw5i",
"dokoak9",
"dokqti6",
"dokoj6z"
],
"text": [
"Your network cable doesn't know what a byte is. It doesn't care whether you are sending 8 bits at a time, or 8000, there is no inherent notion of a byte. Ethernet, for example, operates on octets, three bits at a time, so thinking in terms of bytes is unnatural in that context. In addition, 100 bytes of data on your hard drive probably isn't 100 bytes on your network. Your data is going to be put into groups, and that group will have header data, separators, error correction, etc. That group will be put into another group, with more data, that is put into another group, with more data. All that might be compressed, making it smaller again. The 800 kilobits on your network are not the same as the 100 kilobytes on your disk.",
"I wish there would be! But in reality, I don't think there will be a push to switch. Any company that has a business predicated on how quickly their internet speed can flow (ISPs, router manufacturers, etc.) can put a number that is 8x bigger than the actual amount of traffic it can withstand. It's pretty much Marketing 101, when you can put in some extremely small fine print what the actual speed is, or even just put \"Mbps\" instead of \"MBps\" in small print, knowing the general consumer public won't know the difference. Companies would willingly have to change their marketing style to push Bits out of contention for Bytes. The market dictates this will never happen, given that the first company to do so would see significantly less business due to everyone else having inflated numbers.",
"If you pay for internet service, the connection can transfer a certain number of bits per unit time at maximum speed. How many bytes that translates to is not necessarily constant. Start by reviewing the [OSI model]( URL_0 ). Your ISP provides a basic connection at the media layers: simply passing bits around, and routing. That is usually all. However, most people think in terms of the host layers. \"I am downloading this file in Chrome and it says I get X bytes/sec.\" That translates to 8X bits per second. However, that is using TCP/IP: the raw number of bits your connection can provide are not all dedicated to the contents of that file you are transferring. TCP adds overhead: each packet has timestamps and checksums, so the client knows if a packet is corrupt or was received out of order. Acknowledgement packets are sent in both directions. All of these consume bits. Going back to your question, this is more of a perception issue than anything. Data pipes are generally measured in the number of bits they can transfer because that is what they do. Even the concept of a \"byte\" may be foreign to the physical layer in OSI, for example. People think in terms of bytes, because that is what their web browsers report when transferring files. A byte is the smallest addressable entity in computer memory, and files on a disk are measured in bytes, not bits. Humans are trained to think in bytes. However, overhead ensures that the number of bits at the physical layer of the network is not simply eight times the number of bytes transferred at the application layer. If we started advertising speeds in bytes and classifying connections using bytes, it would _never_ match what people actually see in web browsers or SFTP clients. While it is possible to measure network speeds in terms of bytes, it would not really help anything and could add confusion.",
"Yes, but it's completely drowned out from the marketing department. Sadly, most people are idiots. They'll see service A selling 16MB for $20 and service B selling 2MB for $18 and they'll buy service A. Both of which ignore that it's a rate and ignoring the \"per second\" part of the unit, because while the guys from marketing might have a point, they're also kinda idiots. Where's my 32 nibbles per minute connection?"
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Subsets and Splits