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5n0wyv | How do game developers make different levels of difficulty in their games? | I love to play checkers on my phone, and the beginner and easy levels practically give you the game, it's impossible to lose. The expert and master levels, however, are impossible to win, and games are over in 5-10 moves. I normally play medium or hard levels where I stand a chance to win, but I still have to work for it. But that got me thinking, how are they able to make different levels for the games? Are the easy levels specifically designed to give you the game, and the more harder designed to make it impossible to win? Why is it that the more harder the level, you don't get away with anything playing, and the computer is almost guaranteed the win? Thanks for any insight. | Technology | explainlikeimfive | {
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"There are a lot of different ways this can be done, and I could go into great detail about many algorithms (such as [A*]( URL_0 )), but in order to keep this simple, let's compare it to two human players in a game of chess. Player A barely knows how to move the pieces while Player B is well-practiced and can see 10 moves ahead. Obviously, Player B will win the match; he can look at numerous different situations the game can end up in. He does this by playing \"what if\" scenarios in his mind, then chooses the path with the best outcome that *he has seen so far*. To reduce the difficulty for Player A, Player B might limit himself to only looking 5 moves ahead. Another method of reducing difficulty is to add a timer. Player B only gets 20 seconds to think about his move. Or maybe it's only 10 seconds. Either way, the player is forced to make a move, and may not have time to consider every option available to him. If given *enough time* and *enough processing power / memory*, a computer could theoretically **never lose** a board game like checkers or chess.",
"Another simple way is to: increase the amount of damage an enemy does; decrease dropped loot/experience; larger maps; and another subtle one is actually to change the music being played during a scenario. That's one of my favorites to mess with: increased tempo can lead to higher heart rates, which can cause players to lose focus and mess up more. There's a lot game designers can do aside from changing AI thought patterns."
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5n1nsc | Why are professional video cameras so much larger than professional photography cameras? | Technology | explainlikeimfive | {
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"I think the question you're trying to ask is why professional movie cameras are much larger compared to a professional still camera (for example a DSLR)? A few factors: - Image sensor/film size. A larger sensor or film format will require a larger unit and a larger set of lenses. Note that both still and video cameras come in a variety of sensor/film sizes. You can get a professional still camera that's bigger than a professional video camera. It all depends on the application. - Flexibility. A movie camera lens typically needs a wider zoom range than a still camera, particularly still professionals using primes (non-zoom) lenses. This means bigger, heavier lenses. - Ergonomics. A movie camera needs a greater degree of smooth control over the camera so you can do smooth zooms, smooth pans, smooth tilts etc so there's additional control and mounting hardware. - Movie cameras tend to have a viewing screen as opposed to a small optical viewfinder. - Storage requirements are higher for movie cameras."
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5n3q2q | How IT department turns on your PC even if it shutdown (without anyone physically pressing the on button) | Is this possible | Technology | explainlikeimfive | {
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"They are most likely using [Wake on LAN]( URL_0 ). > Wake-on-LAN (\"WOL\") is implemented using a specially designed packet called a magic packet, which is sent to all computers in a network, among them the computer to be woken up. The magic packet contains the MAC address of the destination computer, an identifying number built into each network interface card (\"NIC\") or other ethernet device in a computer, that enables it to be uniquely recognized and addressed on a network. Powered-down or turned off computers capable of Wake-on-LAN will contain network devices able to \"listen\" to incoming packets in low-power mode while the system is powered down. If a magic packet is received that is directed to the device's MAC address, the NIC signals the computer's power supply or motherboard to initiate system wake-up, much in the same way as pressing the power button would do. ELI5 version: > A computer that is off can have its network card run in lower power listening mode for a message that is used to trigger the computer's wake up procedure. Kinda like a TV on standby waiting for the power button on the remote to be pressed.",
"Yep Wake-on-LAN (WoL) is an Ethernet or token ringcomputer networking standard that allows a computer to be turned on or woken up by a network message. The message is usually sent to the target computer by a program executed on a device connected to the same local area network, such as a smartphone. It is also possible to initiate the message from another network by using subnet directed broadcasts or a WOL gateway service. Equivalent terms include wake on WAN, remote wake-up, power on by LAN, power up by LAN, resume by LAN, resume on LAN and wake up on LAN. If the computer being awakened is communicating via Wi-Fi, a supplementary standard called Wake on Wireless LAN (WoWLAN) must be employed.[1]"
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5n3r2y | How do video game hacks work? | How are cheating tools such as aimbots or wall hacks in shooters made? Do they exploit faults in the games, or are they impossible to prevent? I've heard about people taking time to develop cheats for games, and I've seen aimbots and similar tools used, but I've never known the technical aspects of how they work. | Technology | explainlikeimfive | {
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"Basically, anything that is installed on your pc can be read, written or be modified. So they aren't exploiting weaknesses in the game code, rather, its impossible to prevent someone with admin rights from altering the game if they desire. (It can however, be made very hard) What online games CAN do is simply not tell the pc the information it needs until its fair/legal/proper for them to know. so you could prevent a wallhack/maphack by not telling the computer of the player where the player is, until the server has verified that you should be able to see him. Most Moba's do this, hence there aren't any maphacks for LoL/Dota, FPS games have more lag issues so they can't really implement the above scenario without causing gameplay problems."
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5n5aj4 | Why is it that computers get slower as time goes on, even when you factory reset it? | Technology | explainlikeimfive | {
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"Computers don't get slower. Software just gets more and more demanding, since it's always designed for newer computers. And even if you factory reset the computer, you're going to be getting newer versions of the software, which run more slowly on the old hardware.",
"There are multiple reasons for this: 1. A lot of it is perception. Software is going to get more demanding over time, and your computer will slowly become outdated. 2. The more your drive is fragmented, the slower your computer is at reading from it. Modern computers are less affected by this, as they do defragmentation during any idle time. Also, SSDs have their own way of dealing with fragmentation, and are generally way faster tha HDDs anyway. 3. Dust and degradation of thermal pastes. As your computer gets worse at dissipating heat, elements such as the CPU or GPU will begin to generate more heat. While modern CPU's are rated for some pretty high temps without performance loss, constant overheating will impact performance. 4. General wear and tear on parts. This generally has a minuscule impact on performance, as most parts either work or they don't.",
"Dust can also heat up your computer to a point that it runs slower on purpose to prevent damages. But usually it's the software updates fault.",
"(Assuming Windows 7 - Procedure may be similar for other versions, for example, I know it is very similar or identical on Vista.) •Open the Start menu. (Windows key does this, if you don't know how.) •Type msconfig into the search box in the lower-left and hit enter. (You could instead type msconfig.exe into the command prompt.) •In the 'General' tab (should be open already) select the 'Selective startup' option, if it isn't already. •Go to the 'Services' tab. •Check the 'Hide all Microsoft services' checkbox. •You'll be presented with a list of programs that your computer runs on start-up that are part of other programs you have installed. None of these are needed for your computer to work, and many of them keep running long after startup (thus slowing it down.) Disabling them may cause other programs you have installed to load more slowly when you start them, or to break entirely, but Windows will keep working, and you can always come back here to re-enable things. •Un-check the boxes of any programs you don't need. If you don't know what it is, un-check it. •Go to the 'Startup' tab. •Un-check the boxes of any programs you don't need. If you don't know what it is, un-check it. •Click the 'Apply' button or the 'Ok' button at the bottom of the window, and close the window if it doesn't do it automatically. SOURCE: [WhyIsTheNameGone]( URL_0 )",
"I think what you are referring to is (for the most part) mitigated by switching from HDD to SSD. when you install, uninstall, update, patch, copy etc. stuff it gets fragmented, so most of the stuff that computer uses and needs fast access to looks something like that (A - what we want to read; X - other data): AXXAAXXXXAXXXXAXAXXXXAXAAAAXXXXXXAXXXXXXXAXXXXX.. ..and so on so instead of just grabbing the needed data in one go, system needs to find every fragment. HDDs have latency and seek times and all other fancy things that state how long it would take to read one specified fragment of the disk - in human terms it's very small amount of time, but it all adds up.. It's like you got sent to the store for every item separately instead of all of them at once. The store may be 30 seconds away, but if you need to buy 100 items you'll spend an hour and 40 minutes just walking the distance normally you can hardly notice SSDs may be fragmented as well but, let's say (as far as this example is concerned) they don't care and have \"instantaneous\" access to every fragment My PC for instance (thanks to SSD) is responsive as soon as the desktop is displayed, which means that it of course still loads few stuff in the background (some of which is purposefully delayed by the system) but when I click on chrome it starts immediately. e: word",
"There are many things that can cause this. 1. A lack of hardware work done on the computer. Fans can slow down and the computer will over heat easier. And dust can accumulate on the heat sinks which make them less effective. 2. Hard drives have limited use cycles and run worse as they fill up. Your computer is slowly piling up data all the time without you knowing about it. And even if you delete it, those fragments are still on the hard drive and bog it down."
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5n67qf | Digitally signing message. | Technology | explainlikeimfive | {
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"Public Key Cryptography in a nutshell: You have two keys: a public key (that you can give out to anybody) and a private key (that — you guessed it — you keep private). Both of those keys can be used to either encrypt or decrypt messages. If you encrypt with one key, you can decrypt with the other. By giving out your public key, people can encrypt messages with it so that they know only you can read them (by decrypting with the private key). Encrypting with the private key is useful for digital signatures — we'll get there in a minute. Hash functions in a nutshell: Cryptographic Hash Functions are mathematical constructs that allow you to summarise data into a fixed size summary (called a \"digest\"), in a way that for the same message you always get the same digest, where you can't recover the original message from the digest, and where you can't easily find another message that produces the same summary. This is quite useful, for example, for validating that a downloaded file is correct (For hashes in current use, digests are usually like 20 or 32 characters long, irrespectively of the size of the message being hashed), or for digital signatures (we're getting there!) Digital signatures in a nutshell: Encrypting messages is annoying, because it forces the people on the reading end to have decryption software at the hand to be able to read them. This is fine when you need to keep messages secret, but sometimes what you actually need is to prove to people that it was actually you who sent a message that can perfectly well be shared publicly. A neat way to solve this: You hash the message you're going to send, then encrypt the resulting digest with your private key. It's this encrypted digest that is called a digital signature. Then you add the encrypted digest to the message. The message is still readable as-is, but now it has the signature. Anybody who has your public key can then do the following: - Hash the message themselves - Decrypt the signature with your public key, retrieving the digest you calculated on your end - Compare the digest they calculated with the one in your signature. If they match, then they have proof that you wrote the message yourself (the public/private keys ensure that you encrypted the digest, and the difficulty in finding two messages that hash to the same digest ensures that this is actually the right message) So what's the deal with the request to Julian Assange? Julian Assange has published his public key in the past, and that key is widely known. By asking him to sign a specific message, that user was basically asking JA to prove his identity — Presumably, only JA has the private key that goes with the public key we know to be his, so nobody else would be able to sign the message such that the signature would be valid as coming from JA. By choosing the message himself, he made it impossible for a fake Assange to reuse a message that the real Assange had signed in the past as a way to \"prove\" his identity. There's also the question of whether Assange himself still has access to those keys."
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5n74fw | Why are hackers focusing on the DNC rather than other organizations like the RNC? | Technology | explainlikeimfive | {
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"The FBI and other intelligence groups, as well as the RNC, believe their accounts were compromised by the same actors. The obvious implication is that the hackers have an interest in publicly releasing information from the Democratic party and not any from the Republican party. Given the overwhelming likelihood based on the analysis of intelligence agencies and the private firms who investigated the hack of the DNC, the Russian government is the perpetrator of the hack. The obvious implication would be that the Russian government had an interest in damaging the prospects of the Democratic party in the election.",
"The RNC was hacked as well. But just information on the DNC and various Democratic people were released, because the hacking primarily came from Russia, and Russia wanted Trump to win, so it did what it could to hurt the Democrats in general and Hillary specifically. If the US government was attacked, it creates a rally around the flag effect - people will support the government against Russia. If it is a political party that is hacked, partisans in the media and in the other party will ignore the source and just use the info to attack that party. That's the dynamic you see today, with most Republicans deciding to ignore the intel reports because they benefited from the hack."
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5n7lxj | how do the new robot prosthetic limbs work? | this one has a few parts to it, what makes them be able to move around like fleshy limbs? I always thought it was kind of like a pulley system surgically installed but no fingers moved but now there's all sorts going on. how are they tested, can they move without being connected to someone or do they have people on standby? if someone with all limbs had a prosthetic on them could they use the same type of thing to make it move? if the extra arms can move would they be able to be controlled as separate arms or just copy what the connected arm does? got a little silly at the end but its still something i'd find fun to know. thanks | Technology | explainlikeimfive | {
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"There are a lot of different ways that a prosthetic limb can be made to move, can you supply a more specific example of the kind you have in mind. Most systems will attach something above the elbow and actuate when the elbow is moved, meaning the whole firearm has to be moved up to actuate a grasping mechanism. Some have attempted to use nerve endings directly to control movements, but the nerves often die off from this and makes the interfaces unreliable in the long term. Some will use sensors capable of detecting muscle movements as small as a simple twitch and you learn to twitch certain segments of muscles in the upper arm or shoulder to control the limb's movements. And some even use sensors to read the electrical signals emitted by certain regions of the brain known to control movement of the missing limb to control it's movement."
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5n8mtc | The difference between Java, Javascript, and JSON | Technology | explainlikeimfive | {
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"Java is a four star hotel. It has most everything you need and there are expectations on your behavior. JavaScript is the motel 6. It's quick and dirty, but it will do the job and you can do whatever. JSON is not going to let you spend the night, but it'll give you directions and info on the hotels.",
"Java is a cross-platform, strongly-typed, object-oriented programming language. It runs everything from your phone (unless you use an iPhone at which point... Eh, you're beyond help actually) to your coffee-maker to web applications to your watch. Java applications run client or server side, meaning they'll be on your local machine as standalone applications or running on a server, feeding web pages to your browser or crunching data to put into a database. JavaScript is a cross-browser, dynamically-typed object-oriented scripting language. It is (mostly) responsible for supplying the client-side scripting to webpages that make them look really awesome and do cool animations, have menus and supply dynamically loaded content. There's a lot more to it that there isn't room to explain. JSON stands for JavaScript Object Notation. It's not a programming language but a way to easily, minimally transfer data. It's simply a textual representation of a complex data structure. Every programming language that can communicate with another device, application, IP address etc... Is able to use JSON to communicate (whether they support it or not is an implementation detail). For clarity: I'll try to explain strong vs dynamic typing. It'll be tough and probably not make sense if you're not a developer. Strongly typed languages force you to declare the type of variable you want before you use it. In Java if I want a number, I must declare it as a number and use it as such. In JavaScript I can have a variable be a number but then give it an age property and a street address if I want. HTH",
"Java and JavaScript are programming language. Beside name they have nothing in common that other programming languages have and there is lot of languages that are more similar to Java then JavaScript is. JavaScript is lightweighted and was created to be used on website without being able affect the computer that is using the page. It is used as interpreted language. Java was created as fully-flagged OO language for general purpose. Is used as compiled language that run on virtual machine. JSON is just standard for storing data and is based on JavaScript syntax."
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5n8xgh | Why can't my front windshield have those defroster lines my rear window has that defrost the rear window really quickly? | Technology | explainlikeimfive | {
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"It can, my 2003 Ford Focus has it. The wires are very thin and embedded inside the windscreen. It's a very common option in the UK. Edit. For those of little faith, Google 'Ford Quickclear Windscreen' and prepare for enlightenment.",
"I did some reading and everything I found said it basically comes down to price. Some companies have made models with front defrost, but it's expensive, and the windshield is expensive to replace. Since front windshields are more likely to get chipped or cracked, they don't put them on cars intended to be inexpensive.",
"Not ELI5, but this [post]( URL_0 ) might help you understand.",
"I could be wrong, but didn't Ford get rid of heated windshields because they mess up red light cameras? The metallic coating reflects the flash from the camera and ruins the photo, meaning no ticket or revenue for the city.",
"I drive a 1995 F250 7.3 powerstroke. Use the hot steamy kisses of all the women I pick up to clear my windshield.",
"Ford had this back to 1987 on some Lincolns with cold weather packages. The windshield had a thin transparent sheet of gold sandwiched between the layers. Upon activation the alternator was full fielded and 140 amps of electricity was delivered to heat the windshield. Really effective when it worked, an incredibly expensive clusterfuck when it burned up the alternator, and harness when it didn't work. Need a new windshield...$3K please, and that was if they were available.",
"Automotive HVAC engineer here! My job literally is responsible for windshield clearing. As other people have pointed out, there are some cars that use the heated wiring up front. I sat in a Range Rover that had it. They were very, very fine zigzag wires across the windshield that could only be seen when focusing your eyes on it. When driving, it wasn't noticable in the slightest. Something that new cars have now is what's called a PTC. This is essentially an electric heater that provides warm air before the engine has had time to warm up the coolant running through the heater core. The air that comes out of it isn't hot, but it's still warm and instantly available on a cold day. Also, most cars offer remote start, which does wonders for clearing the glass in the morning.",
"Some do. Just many thin wires instead of thick ones. It was a 400$ upgrade in my range rover. Curious to see what other vehicles offer it Edit:dirty and dark picture but here's proof URL_0",
"Some cars do have this. Most don't because people in hot places would have no use for this, and it costs money to give this to a car. Front windshields get broken lots more than rear windows, so they need to be simple and cheap or the hot place people would be mad about their money. edit: simpler words for the subreddit this post will go to",
"I was about to say \"yeah right, the lines would wreck your visibility and you can just blast the heater on the windshield vent\" but then I realized I have no idea what I'm talking about because my idea of what a car has is based largely off my totally barebones 2000 Corolla.",
"My 2016 Subaru Crosstrek has them where the windshield wipers come to rest. Has made all the difference in the world on cold crappy days.",
"This must be an annual favourite question. Here are a few more threads of the same question: [One]( URL_1 ) [Two]( URL_3 ) [Three]( URL_0 ) [Four]( URL_2 ) My favourite answer is that the windshields would be very expensive to replace.",
"And while we're on the topic, why in the world don't we have heated roads by now???",
"This is one of those great simple questions we never think to ask. If I were given the choice, I'd want a front windshield defrost before the almost standard rear one. All the vehicles, other than pickup trucks, had rear defrost.",
"It's already been pointed out that some Ford's have it, and to my knowledge they hold the rights to it by patent or something similar. I remember my dad's 2003 S Type Jaguar had it, because at the time Ford owned Jaguar.",
"I'm confused. My front windshield defrosts faster without those lines. By back windshield takes forever.",
"You can buy electric 12v windshield heaters or you can put your Sun shade on the outside of the car, they even make ice shades just for this. URL_0",
"Just throw hot water on it straight out of the kettle!!! It wont break your windscreen i promise!!!",
"This thread has turned into a lot of \"I have a [car and year] and it [has/doesn't have] a heated windshield\"",
"My parents Volvos both have them. You can only really see them if you focus on them, otherwise it's unnoticeable. VERY helpful in freezing rain though:)",
"Some cards have it, but they are EXTREMELY expensive to replace in comparison to the regular ones, and your front window is much more likely to get broken.",
"My 2015 \"Cold Weather Package\" Jeep Cherokee has defrost lines in the bottom corners of the windshield for the areas the wipers can't reach. But not the whole windshield.",
"You know what's worse? When it's so hot and humid outside that running the a/c inside the car fogs up the windshield and creates condensation that doesn't go away unless you constantly run the windshield wipers. Fucking Florida...",
"G-Wagons, W463, have them. Be careful what you wish for though, they are pricey when it comes time for replacement! Another tech thing that I wish all cars had, electric heaters for instant heat until the engine gets to operating temp. If you have ever driven a diesel in a cold environment you definitely understand!",
"It's an eternity to defrost because your starting with the heat. Start with the AC and let it clear up. Once the window is clear switch to heat. It should only take 30 seconds maximum on AC to clean it off. Fogged windows are due to temperature differential, and unless you have electric instant heat your gonna have to do this dance haha.",
"It can. It's an option on Mercedes Benz S-class in the United States, for example. Ford owns a patent for this in the UK, where demand for such a feature is much higher due to the climate and thus offering it as a widely available feature across a brand of mass-market, lower-end cars actually makes economic sense. They call it [Quickclear]( URL_0 ) and it's been available for decades.",
"If you live in the us, thank our ridiculous federal government, who has to manage every aspect of our lives. We lose a lot of features on our cars, thanks to the dot and other dumb agencies. Ex: We can't have glass headlights, because god forbid someone might get cut, but it's ok if you can't see 10ft in front of your car at night, since your plastic lights fogged over.",
"Although it sounds like a nice idea to have electric defrost on our front windshields, I think there are several reasons that it's not done (or commonly done): 1) The air vents and heater core are already up front, so hot air is a very easy implementation that's already been in place for a long time. 2) The visible wires across the windshield would be annoying to the driver. The wires in the rear windshield aren't as annoying because you don't look out of the rear as often and don't need to see as much detail... and people are already used to it. 3) It would increase cost and the majority of people (especially in hot weather climates) wouldn't want to pay extra for it.",
"My friend's Jaguar has them. I figured it was an extra fancy option for luxury cars, but someone mentioned it's a common option in the UK, so maybe Jaguar just has it all the time because British. They're extremely thin and rather wavy, unlike the rather thick and grid-shaped wires (most?) cars have in the back window. You don't notice them when you don't look for them, but as a passenger, it can be irritating to stare through them. As a driver I almost never notice them, but when he's driving, I sometimes just look out of the side window to get my eyes off the wobbly lines. Not sure how that works, probably because you're focused on the road for driving reasons, and not just for bored sightseeing. So personally, I would say it has two reasons. It's expensive to put in there (or at least more expensive than not putting it in there), so warm regions don't have it for the two to four weeks of snow and frost they have. And it can be a bit distracting, and the front shield should be as clear as possible, so you shouldn't have them if you won't use them.",
"your front windshields after a certain date are made of [glass-plastic-glass laminate]( URL_0 ). This is likely to have very different thermal characteristics than straight glass windows (like the rear window, which is tempered glass). \"defrosting\" comes in two forms. The first involves removing condensation build-up on the inside of the windshield. Typically, this requires a heater and blower to get the air temperature up enough to absorb the moisture that humans emit when they exhale. Secondarily, this normalizes the temperature of the windshield with the temperature of the high humidity air being exhaled (which gets mixed with the cool air inside the vehicle to create a lower temperature, super saturated atmosphere that will condense moisture/frost on anything even a few degrees colder). Next, there's the shit on the outside of the windshield. Frost mostly. Ever try to \"defrost\" a windshield with snow on it? Takes forever. and generally only creates lines between the snow. There's a certain \"ice mass\" that these types of defrosting systems can tolerate and they work on outside frost due to the high thermal conductivity of glass. Throw a layer of plastic laminate between inner and outer glass layers and they probably don't work very well at all. Now.... if you were able to invent a electrically resistive (in a manner that produced a thermal by-product) plastic that could be used as a laminate for front windshields, I'd bet you could make quite a bit of money selling it to the automotive industry."
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"https://www.reddit.com/r/explainlikeimfive/comments/2p57t3/eli5_why_dont_front_windshields_have_electric/",
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"https://www.reddit.com/r/answers/comments/2o9z52/why_dont_all_windows_on_the_car_have_defroster/",
"https://www.reddit.com/r/explainlikeimfive/comments/2o9b4z/eli5_why_do_cars_only_have_defroster_grids_in_the/"
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5n90ia | How does a mechanical keyboard improve typing speed? | I'm already a pretty swift typer, but my dad is a notoriously slow typer. I let him take a look at my clickity-clackity mechanical keyboard, and he was able to type at a much rate than normal (he still typed with one finger on each hand regardless, but quicker than usual). Is it the difference in tactile and sound feedback vs a membrane keyboard? edits: sentence structure, spelling, and word choice | Technology | explainlikeimfive | {
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"text": [
"Tactile feedback is improved, resulting in less missed keys, AND key actuation rate (the speed at which the keys move up and down) is greatly improved, resulting in a more fluid key movement, which can contribute quite a bit to speed."
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5n9ehk | Have Any Technologies Peaked? | Technology | explainlikeimfive | {
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"text": [
"Firearms. We can keep making them to tighter tolerances by shaving off thousandths of inches here and there, but the fact is the designs are pretty much perfected. You can't do much to alter the basic physics involved in feeding bullets into a gun. Even experts agree that unless a radically new kind of technology shows up (like directed energy weapons) the basic design of a gun isn't going to change much. There have been some innovations like the Kriss Vector, but results have been mixed and the jury is still out on it.",
"Since almost anything could be made out of improved materials, it is hard to prove that anything has actually peaked. Even extremely boring things, like pencils or belts or socks or tables, clearly can be improved if someone invents a superior material to make them out of.",
"Another question is, what can be improved upon, but other things take priority and therefore isn't researched? Look at basic hand tools, hammers and screwdrivers, or garden tools for example. You might see someone add a better grip or some simple twist, but a hammer is a hammer. Can that simple thing be improved upon? Do we bother to try? Or is the simple design all we need?"
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5n9o1r | When a phone dies how does it still have enough power to tell me it is dead? | When a phone dies, how/where does it get the power to show the screen of the dead battery? | Technology | explainlikeimfive | {
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"text": [
"Because you phone isn't completely dead yet. It \"shuts down\" when it has a small about of power left and uses that remaining power to display the low power message and keep your data open.",
"Lithium-ion batteries are never intentionally drained to zero; doing so would cause irreversible damage, and possibly create an unsafe situation. Instead, devices will cut off at some point to avoid damaging the battery. To reassure users that their phone is still in working order, but with a low battery, the phone may turn on the screen for a brief moment and/or flash a LED."
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5na3es | How do search engines know how long someone spends on your site? | I'm learning SEO and I was told to focus on getting traffic so people visit my site, and making the site great so people stay on it. And when search engines see that users stay on my site then they (SE's) will send me traffic. But how do search engines track how many people come to my site and how long they stay? How do they know where people are going online? | Technology | explainlikeimfive | {
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"They know when someone clicks a link on the search engine, and they know if someone goes back to the search results after visiting. If people open your site and don't go back, or take a while before they go back, it means they probably liked your site. If they go back to the search results right away, it means they probably didn't like your site."
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5na9sv | Google Translate's forming its own language | I have read a few articles about this but I'm still very confused. I am not sure if this is something that is able to be explained simply, but it would be great if someone could try!! | Technology | explainlikeimfive | {
"a_id": [
"dc9ztde"
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"text": [
"An article about it from Google: URL_1 Little bit about training neural networks: URL_0 An artificial neural network was trained for different language pairs. To much surprise, they found the same (or somehow similar) neurons activate for phrases with the same meaning for different language pairs. It's thought that this means the network encodes something common to all languages (such as meaning). That is, instead of translating cow (english) to vaca (spanish), it's translating cow to some internal phrase to vaca. The same internal phrase should activate when translating vaca to lehmä (finnish). Interestingly, this wasn't intended. Training artificial neural networks is somewhat of an automatic process. The training process happened to create the internal language on its own. The internal language isn't a language in a normal sense, being able to be spoken or written. Rather, it's set of clusters of neurons where each cluster has a unique meaning."
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5nb4vi | How did Reddit get so popular? Who were the first group of people to find Reddit, and how did they come across it? | Technology | explainlikeimfive | {
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"Actually the two founders Steve Huffman and Alexis Ohanian made a bunch of fake accounts to post links on other websites guiding to their newly created website that they just put online with the help of a start up company. The rest is history.",
"Summer of 2005, Paul Graham (one of our investors) wrote a blog post and linked to us in it a few weeks after we launched the site. That was our first flood of traffic and a lot of those folks stuck around.",
"I'm pretty sure it started as a place for people in the tech industry to share articles. You couldn't even comment at first - in fact, the very first comment of all time was in response to the post announcing that you could comment, and it was someone complaining that it would ruin reddit. Someone will post the link shortly I'm sure! Another thing, subreddits didn't exist either. I think the original got moved to /r/reddit when subs were introduced. Edit: spelling",
"This is my 10th year here, but not on this account. I started at URL_1 and found Reddit on a news-aggregator aggregator ( URL_0 ) It contained Fark, Reddit and Digg, among others. Fark faded, and Digg collapsed. Many ended up here. If you want a feel for what Reddit was like in the \"olden days\", check out URL_2 ."
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5nb6c9 | Why can cameras record 4K-25fps, FHD-50fps but not 4K-50fps or more? | My new camera (Panasonic FZ1000) can record in 4K - 25fps, but can also do FHD at 50fps and even HD at 100fps. The [Wikipedia]( URL_0 ) page even says that it has more capabilities, but restrained by the firmware : * Full HD 1920×1080: 100 or 120 fps * HD 720p 1280×720: 200 or 240 fps * 640×360: 300 or 360 fps I found this to be quite common on modern cameras, and apparently there is even high-speed cameras used to record explosions or bullets for example that can go much higher by reducing pixel density. How do this process work? *Why do we need to reduce pixel density to increase fps?* Why can’t a camera record at 4K - 50 fps for example if it can do FHD - 50fps? Is it about processing power, data size or is it about the mechanics of image capture? Also, is there a limit or a record of the maximum frames per second achievable? | Technology | explainlikeimfive | {
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"text": [
"> processing power, data size That's exactly it. Larger resolution and FPS require more processing power as well as more bandwidth to transfer the large amount of data to the camera's storage."
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5ncq5d | How does developers input "traps" in their software for pirated copies? How do they distinguish between real and pirate, and why can't someone just upload new copies without it? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"This is called \"digital rights management\", or DRM. DRM comes in a variety of forms. When software came with printed manuals, sometimes there'd be information on the manual the program would force you to enter. Later, when software came on CD's, often extra DRM data on the CD was written in non-standard locations that can be read by most CD drives through low-level operating system calls, but cannot be written by most home CD burners. For game consoles, games use proprietary cartridges or discs that are different from normal forms of those media. The console manufacturer basically tightly controls the production of physical copies of games. So for the most part, you can't e.g. simply use a normal DVD burner to make copies of Wii games. These days, where most software is bought and sold on the internet, DRM has to take a different approach because there's no physical stuff you can put extra required information on. It often involves the software contacting a server being run by the publisher (or the contractor providing the DRM technology), and ensuring the usage of the software is authorized. For example it may check that the serial number is legitimate, or it may require the user to login to an account. It will also generally deny access to serial numbers or user accounts that are seen in multiple locations. > why can't someone just upload new copies without it? This is called \"cracking\", \"warez\" or \"software piracy.\" It takes some technical sophistication to figure out how to crack software, and it's illegal in the US. That doesn't stop people from doing it though. A lot of times the people who crack software also insert malware -- cracked versions of the Windows operating system are especially notorious for being crawling with malware. Many users regard DRM as evil. Some reasons for this: - If the company running the DRM server goes out of business or decides to shut down the server one day, software you've bought may stop working. - If the DRM requires an internet connection, you can't use it if you don't have an internet connection available. - It makes it difficult to create backup copies of software, in case the physical copy wears out or is accidentally destroyed (for example in a fire or flood). - If DRM locks the software to a particular machine, you have to purchase a new copy of the software if you buy a new machine or perform extensive hardware upgrades. - DRM fails of its objective of preventing piracy. Despite using the best available DRM technology, cracked versions of popular software tend to quickly appear after release. - DRM assumes users are criminals. This is very insulting."
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5nctu9 | how secure / anonymous are texting apps? How easily can cops trace it? | I was in an argument with a friend about the anonymity of texting apps / burner apps / Skype calling, and I wanted to know, say if you don't use your actual email or information, how easy is it to still trace it to the user? | Technology | explainlikeimfive | {
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"text": [
"It depends on the specific app. For some apps, it's not private at all. For others, it's possible for them to see who you're texting but not the contents of the text. Others are completely private. In some cases, the answer is \"it depends\". WhatsApp, for example, didn't used to be private until recently - and it's only private if everyone in a chat has a reasonably up-to-date version of the app. When you create a new conversation in WhatsApp, it will show a message saying that the chat is private (if it is)."
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5ndasr | Explain AMD Risen. What's the Hype? | Technology | explainlikeimfive | {
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"text": [
"AMD is a company that makes processor chips, like Intel. AMD is trying to pitch their new **Ryzen** CPU as a solid competitor against Intel and their tech demo is a topic of much discussion about how it stacks up against the usually dominant Intel's current offerings.",
"For the last 3-5 years, AMD hasn't come close to Intel's single core performance. With their new Ryzen, they claim to have made a huge improvement in single core performance, going (almost) toe to toe with Intel's latest CPU's. This would mean Intel finally has a competitor again, and AMD could be offering an almost equal performance at a much lower price."
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5ndv23 | how does my phone calculate how many flights of stairs went up? | I've seen references to things likes atmospheric pressure, but then would going up an elevator ruin my stats? (I work on the 40th floor of a building) | Technology | explainlikeimfive | {
"a_id": [
"dcap9wh"
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"text": [
"Your phone can use a combination of barometer, accelerometer, and GPS to determine your change in elevation over time as well as whether it's through being lifted or by stepping. The accelerometer is key, here, because it can determine acceleration and in what direction, so it will measure a single period of acceleration until the elevator reaches a steady speed, and then constant graduation in elevation without further activity. Walking up stairs consists of several consecutive thrusts of acceleration, one for each step. The motion is distinctive and can be differentiated from an elevator. And you can't trick the thing by walking around in an elevator because your upward velocity is constant, so there's no vertical acceleration as you step about horizontally."
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5ne1yc | If cochlear implants communicate directly with the brain using electrical signals to fix deafness, why can we not yet use the same principle to correct blindness, or even possibly create virtual reality capable of full cognitive immersion? | Edit: Thanks for all the answers! | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"The ear basically transmits information to the auditory nerve and then the brain deals with processing the information it receives. The eye has a lot more \"pre-processing\" before any information gets to the brain. Networks of neurons within the eye process information to a certain extent before this information is sent to the brain. This is a lot harder to replicate with electronics. The other issue is that the ear is a stationary thing. The eyeball moves all over the place to focus on different things, so with a \"fake eye\" we would have to hook into the nerves that go to eye muscles in order for the fake eye to know what the brain wants to look at. While vision and hearing are both very complicated processes, I would say that vision is overall a lot harder to replicate with electronics. But as others has said, research is ongoing and there has been limited success. I'm sure vision implants will be a thing one day.",
"Also cochlear implants don't \"fix\" deafness they work for some ppl but not all and even for those they do \"work\" for don't hear the way someone who was born with full hearing does. Both hearing aids and cochlear implants work best at 3 feet. They also pick up then amplify every sound there is and it can be really difficult to work out what you are suppose to be hearing."
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5ne67k | ; how does a computer game mimic the laws of physics. | how does a game or app on a computer or phone mimic the laws of physics, for example when I am playing pool on my phone, and i hit the cue ball with slightly more or less force, how is that translated in computer code to make the balls i hit move in a way they would in real life. | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"The basic physics stuff is pretty easy, just have to keep track of a few parameters. Location, Velocity, and Acceleration. For the most part interactions can be defined simply setting acceleration. For each simulation cycle start by setting acceleration to zero (nothing happens unless a force is applied). Moving through air, and don't want to simulate drag? Simply don't add anything to the acceleration. Want to include gravity? Add gravity to the acceleration so you fall it's (9.81m/s^2), got a rocket engine pointing up? Add it's acceleration to what you have (-15m/s^2). Are you moving through water and want to simulate drag? It's opposite and exponentially proportional to velocity, so add -velocity^2 \\*waterThickness to acceleration. Did you hit a brick wall? Ignore the other forces and reset acceleration to zero, did you hit a bouncy wall? Multiply the acceleration by -1. By adding up all the different accelerations for different reasons you get the net acceleration an object is under. Then calculating everything means figuring out the time step(usually 1/60th of a second) and then determining everything else just velocity=velocity+acceleration\\*timeStep; position = position+velocity\\*timeStep; In practice you have an acceleration, velocity, and position for each direction (x, y, z), all formulas are done three times for each direction. That gives you three positions (x, y, z), and you give it to the graphics/etc to show it's current position on the screen."
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5nenez | How did Facebook know I might be friends with a person in another city, when I've given them almost no information? | I made my first Facebook account ever yesterday, and I used a brand new email address for it. I gave neither the email provider or Facebook any personal information beyond my name and I think my birthday. Somehow, within hours, Facebook was able to determine that I might be friends with a guy I used to know who lives in another city now. I want to reiterate, neither Facebook or the email provider has my * phone number * address * school information * employment information Also, I didn't download the Facebook app. | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Perhaps that person has you in a virtual address book on their email, phone etc which they have given permission for FB to link through. You gave FB your name, it sees your name on his contact list and suggests the connection.",
"Have you accepted any friend requests or sent any friend requests to anyone? If so, it most likely recognizes mutual friends."
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5nfqib | How are the new Intel processors better than older ones even if they're running at the same speed and have the same number of cores? | For example, I currently have a 6600k, but I've heard that the 7600k is better even if both are running at 3.5ghz and have 4 cores. | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Alright, take it like this: A processor is a laborer who's job it is to take loads of materials up to the architect and builders. Other laborers might be able to move up and down the hill just as fast as our laborer, but are less efficient with the loads that they bring. Every five minutes our laborer takes two armfuls of materials up the hill, with another third load, on his back. The loads are already pre-sorted, and grouped for efficiency. The other laborers can only carry one load at best, and cannot do operations on the load they are carrying, such as sorting or math. At the end of the day the other laborers, have made the same amount of trips up the hill, maybe even more. However, our laborer has allowed for more work to have been done. In short his work per cycle was higher. In a processor, the frequency (e.g. 3.2ghz) is the amount of cycles, or \"trips up the hill\" done in one second. 1Hz would be one \"trip up the hill.\" 3.2gHz would be 3.2x10^9Hz or 3,200,000,000 \"trips up the hill.\" Old pentium processors had a high rate of cycles, but did very little work per cycle. Cores in a processor can be viewed as our laborer being able to call in his friends to help with the work. But, these friends end up standing around, and are only useful if the architect designed the project to have multiple tasks that multiple people could work on. If four columns have to be constructed, then 4 efficient laborers could bring the materials quickly. If only one column is needed, the four laborers would not be needed. One laborer could bring the materials just as quickly as the task cannot be sub-divided, or in computer speak \"multi-threaded.\""
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5ng36m | How do illegal key generators work? | If i were so inclined I could download an illegal copy of windows get a key generator and activate windows. How is it possible for an illegal key generator to generate valid windows keys? Or keys in general? | Technology | explainlikeimfive | {
"a_id": [
"dcb9emo"
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"text": [
"The software maker typically uses a computer algorithm to generate their keys. The key it generates will follow a certain pattern that the maker knows and when you install the software and activate it using the key it checks to see if it matches that pattern (I'm ignoring online activation methods). The software doesn't have a list of valid keys since storing that information would take up a lot of space. So how do the pirated key generators work? 1. They either get their hands on a large number of legitimate keys and try and look for the pattern used to make them. Once they figure that out they can just make new ones the same way the software maker does. 2. They have analyzed the software to try and find clues to the pattern by how it checks the key that is entered. 3. They just got a hold of a number of keys legitimate keys that their keys generator just picks one at random to display. I. This case they aren't really generating new keys just giving out legitimate keys that they got a hold of. Now a days most software has some sort of online activation component that checks the key you entered with a database somewhere to see if it has in fact been issued by the software maker and if it has already been used or not. This is why many programs now also need to be 'cracked' too where the crackers try and replace the key checking code with something that will accept non-legitimate keys or to block the online check and just return a fake response from the server's saying the key is good."
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5ng3cs | How do radio stations broadcast album art? | Technology | explainlikeimfive | {
"a_id": [
"dcb9dxf"
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"text": [
"Radio stations have extra radio bandwidth that they don't need for the audio alone. They can use this bandwidth to send additional data to your radio such as the station name, song title, artist, or I guess the album art. It's essentially sending data over a wireless internet connection, point-to-point from the station to your radio. This is not an efficient connection though due to the distance and interference, so its uses are limited. You usually need a radio capable of receiving this kind of data (and a station properly equipped) otherwise your radio doesn't know how to interpret this data and display it for you. It would just think it was noise and ignore that part of the signal. This system is also heavily regulated in how it can be used."
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5ngms2 | How does a surface-to-air missile (SAM) distinguish hostile aircrafts from friendly aircrafts? | Technology | explainlikeimfive | {
"a_id": [
"dcbc94z",
"dcbdn1m"
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"text": [
"The typical SAM can't tell the difference between friendlies and hostiles. For systems where the SAM is guided from the ground, it's up to the operator to make that call.",
"Aircraft carry a transmitter called an IFF (interrogator friend or foe) transponder. It can transmit a code that identifies an aircraft as friendly. However, that isn't exactly the answer, be a use the missile doesn't read the IFF code. The shooter would be responsible for identifying the target, not the missile itself."
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5nhhy2 | How does the Crocodile Dentist toy work? | [Video ]( URL_1 ) [Amazon]( URL_0 ) You open the crocodile mouth and press his teeth. If you press the sore one, there only one and it is randomized each time the mouth open, he'll bite. The toy doesn't use any battery, so it must be fully mechanical. I wonder how the sore tooth is randomized? I tried to record the sequence, but it doesn't seem to have a predetermined order. Can someone explain this to me? | Technology | explainlikeimfive | {
"a_id": [
"dcbkypf",
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"text": [
"My guess is there is a disk directly below the disk that has holes for safe teeth to get pushed down through. The triggering tooth pushes the disk down and triggers the jaw to close. The disk gets spun every time you open the jaws and is randomized by that spinning.",
"It's been a while since I researched this, so my facts may be a little fuzzy, but like /u/digitaluddite said it uses a disk. Opening the jaw loads a spring for energy storage, and pressing the trigger tooth releases the energy, causing the disk to spin and the jaw to close. The disk has an inaccurate breaking mechanism that causes it to stop at a new random location."
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5nigf4 | Why do web pages viewed on mobile devices keep changing layout as they load, and then change again just as you try to tap a link after it seems like they were finished loading? | Technology | explainlikeimfive | {
"a_id": [
"dcbrt3r"
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"text": [
"Main reason is asymetric loading of elements and bad programming. In detail: The main goal of a mobile page is to load as fast as possible. There are certain methods to achieve this. The two most important (for your question) are: 1) Load visible stuff first: The first things that will be loaded are things you see when you open the web page. Everything \"below the fold\" (below the point where you need to scroll to see it) will be loaded at a later point. 2) Load bigger elements later: Bigger elements, such as images, will be loaded last. So your initial page is loaded fast, and the rest comes at a later point. Now to your problem with the layout changes: Poor programming causes this. Normally you would place blank placeholders for big elements like images. For example: If you, as a programmer, know, that there is an image that is 500x500 pixel, you will reserve this 500x500 spot with a blank white space. So when the image loads (after the initial loading of the page) you can fill this blank space with the image, without destroying the layout. OR you could use two different image qualities. Like one really low quality (and low filesize) one that loads when you open the page (in case the image is in your \"initial load view\") and when this initial load is over, you use your \"normal\" bigger size image to replace the old one. Really sorry, for a non native speaker its kinda hard to explain this :( I hope you get my point."
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5nj2lt | Why there is no remote finder button on TV, to track lost remote? | Technology | explainlikeimfive | {
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"You would need to add a transmitter to the tv and a repeater on your remote. And costs aside you usually lose your remote quite close to the TV, even though sometimes seems to have been sucked into another dimension."
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5njg37 | how passwords work? what happens in the backend when you type password in gmail,facebook etc?what about phone passwords? | Technology | explainlikeimfive | {
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"Well at is most basic you type in something and the computer checks that against the value stored in a database. You might enter \"gaussianpc\" as your username and \"hunter2\" as your password and the computer checks a table of usernames and passwords if the password next to the username your gave is the same as the one you typed. Of course this is an extremely stupid way to do it and nobody does it like that anymore. Instead of writing the password into its table of passwords exactly as you tryped it in the normal way is to \"hash\" it first. Instead of writing your password as it is, it is first run through an algorithm and turned into something like this: \"f3bbbd66a63d4bf1747940578ec3d0103530e21d\". The same password is always turned into the same hash, but anyone reading the table won't know what to type since it is not easily reversed. This means that even the people working at google or facebook or whatever can't easily know what your password is and for example try to use it steal data from a different account where you used the same password. Of course the system is not fool proof and many screw up when trying to build it, but generally the only place your password should be stored permanently is in your head."
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5nk1t3 | Why is a video taken from my phone camera a couple GB but a movie which is much longer is about the same size? | I took a 9 minute video (1080p) from my phone the other day, and it turned out to about 1.38 gigs. But a downloaded movie of the same quality (1080p) is often 1.4 or 1.5 GB while retaining the same quality? | Technology | explainlikeimfive | {
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"It is possible to significantly compress video, but it takes a lot of computing power, too much for your phone to do it on the fly. You could take your video, run it through a conversion and compression process for an hour or so, and wind up with something much smaller that looks pretty much the same.",
"Video compression has some characteristics which affect how it is saved: * It can aim for *more effective* compression to create small files, which takes longer at the \"create\" step, so that it can easily decompress it during the \"playback\" stage; * It can aim for *fast* compression, which cannot make files as small but it can compress at faster speeds, which is a step up from storing the huge raw data of a video file. So, when you're camera is trying to save your video while you're filming it, the camera is taking option 2: it does not have enough time to compress the video file well and still have high quality video. The camera has to save each frame at the framerate speed, because in 1/30th of a second there will be another frame to compress, so it can't waste time making higher-compressed data. The videos you download from the internet were created on server who doesn't care how long it takes to compress a file -- it starts with a lesser-compressed video format, and if it takes five hours to compress that one hour movie down to the tiniest file it can possibly get, it has plenty of time to do so. This is to optimize the file for downloading, so the tradeoff of saving bandwidth is slower compression time. Also , different codecs are optimized for those two different options; the codec your phone is using is optimized for fastness, but the video you downloaded was optimized for smallness. If you were to use a program like Handbrake and convert your phone video to a smaller-file optimized codec, it probably would run for 10x as long as the video takes to play, but it will be a much, much smaller file.",
"The short answer is because it's harder to compress than it is to decompress. Ever unboxed an inflatable bed or innertube that came in an impossibly small box? Taking it out and inflating it is easy. Deflating it and squeezing it back into the original box is harder. Video works the same way. Compressing video is done by looking for patterns in the video. Every single frame is compared to frames before and after it to look for similar elements. The resulting video file is made smaller by describing only the *differences* between frames. Decoding is relatively easy. To play a video, your computer just has to read the video format which says something like: to draw frame 757, take frame 756, but then add this rectangle from frame 755 and move it up 3 pixels, and then change these pixels to these different colors. It's very fast and straightforward to decode. Encoding a video well is hard. For every frame you have to search all over dozens of previous and subsequent frames for similarities and decide which ones are the best matches. With more effort you can compress the same video into much less space with very little loss in quality. So anyway, your phone isn't capable of compressing video very well. It can only compress a tiny bit. Later when you copy the video to your computer you can use the more powerful processor on your computer, and the benefit of more time to spare, to compress the video smaller.",
"I assume you torrented it, as a 2hr movie on iTunes is about 5GB. Either way, an Arri Alexa or a RED normally shoots at > 100GB/min for 2K 24fps. The reason is a difference in the degree of compression, which is why Blu-ray looks better than YouTube. YouTube streams 30fps 1080p at around 3Mbps, while Bluray is usually ~24-32 Mbps. Video Compression is usually done by taking neighboring pixels of similar color and making them one color, thus removing a ton of data. [Apple's movie trailers are of higher quality than YouTube's, so I made a small comparison album]( URL_0 ). Also, did you film in 60fps? Because that's about 20Mbps, which is higher than normal for 30fps, most phones record at ~17.3Mbps. Not a big difference, but if you did record at 30fps, that's good as it preserved more data than ususal. If you did record at 60fps, most phones are at ~23Mbps, so yours is below average. **TLDR:** > while retaining the same quality. It doesn't."
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5nkds8 | While being put "on hold" on the phone, why do songs played have such dreadful quality, while voices come through just fine? | Technology | explainlikeimfive | {
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"It's a combination of a number of factors, but the biggest issue is that phone lines have been \"optimized\" to favor voice sounds over other sounds, and as a result many of the upper and lower frequencies that make up the music you're listening to get cut out by the phone's filters. In other words, it doesn't sound like voice, so it gets cut. The result is that the music you hear is messed up. Combine that with systems that play low quality music files/sources to begin with and you can see how things get really bad.",
"They are compressed to hell and have the bit rate lowered so that they can be transmitted over traditional phone lines.",
"Phone lines only transmit the narrow range of frequencies that are used in human speech. Music is comprised of a much wider range of frequencies, and sounds bad when a large amount of them are removed."
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5nkjtv | How do companies profit from data? | Example: So I use facebook, I give them my typical information. I also post bits about myself that facebook has legal access to. What do with this data to somehow make money from my account? | Technology | explainlikeimfive | {
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"They can use your data to target better ads to you, which allows them to charge companies more to place those ads. For example if there are all sorts of pictures of you skiing, ads for ski gear might be more effective to you than to Joe Random.",
"I work for a company that run ads on Facebook. Because of all the data they have, we can specify that we want to target people between X-Y age, what gender, what income, what interests, what other companies the like, etc. This allows our marketing to be much more effective and cost effective because we are not wasting money on marketing to people unlikely to become customers. For example, let's say that BMW wants to market a new vehicle. They could run general ads to a broad audience and pay a lot of money for people clicking on the ads who like cars and like BMWs, but aren't old enough to drive, can't afford one, or aren't in the market to buy a new car right now. Or they can run an ad on Facebook targeting men 35-60, with incomes over $100k who like other luxury car makers. Maybe they even see a correlation to less obvious connections, like people fitting those requirements that watch Mad Men and are foodies are twice as likely to buy a BMW. So they're willing to pay more to reach these people compared to the FB population in general since they are much more qualified leads."
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5nkra0 | Booleans in C Programming? | I don't know why but the explanation to Booleans is not sinking in, I'm finding the explanations more and more confusing everytime I read over them. Can I have a simplified explanation of this? > When using if statements, you will often wish to check multiple different conditions. You must understand the Boolean operators OR, NOT, and AND. The boolean operators function in a similar way to the comparison operators: each returns 0 if evaluates to FALSE or 1 if it evaluates to TRUE. > NOT: The NOT operator accepts one input. If that input is TRUE, it returns FALSE, and if that input is FALSE, it returns TRUE. For example, NOT (1) evaluates to 0, and NOT (0) evaluates to 1. NOT (any number but zero) evaluates to 0. In C NOT is written as !. NOT is evaluated prior to both AND and OR. > AND: This is another important command. AND returns TRUE if both inputs are TRUE (if 'this' AND 'that' are true). (1) AND (0) would evaluate to zero because one of the inputs is false (both must be TRUE for it to evaluate to TRUE). (1) AND (1) evaluates to 1. (any number but 0) AND (0) evaluates to 0. The AND operator is written & & in C. Do not be confused by thinking it checks equality between numbers: it does not. Keep in mind that the AND operator is evaluated before the OR operator. > OR: Very useful is the OR statement! If either (or both) of the two values it checks are TRUE then it returns TRUE. For example, (1) OR (0) evaluates to 1. (0) OR (0) evaluates to 0. The OR is written as || in C. Those are the pipe characters. On your keyboard, they may look like a stretched colon. On my computer the pipe shares its key with \. Keep in mind that OR will be evaluated after AND. [Source link to explanation, it's at the bottom of the sites]( URL_0 ) | Technology | explainlikeimfive | {
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"I've programmed in C/C++ for almost twenty years and I had trouble following that as well. To be fair to the guy, it is often hard to explain things which have become second nature. When in doubt, use parentheses! The extra characters don't make the code any slower but it'll be much easier to read. Remember that someone may have to debug into this code later (and it could be you). That said, one useful trick with AND's and OR's is that they will return early if the rest of the expression is not necessary. if (first_function() || second_function())) ... the second_function() is skipped if the first_function() returns true. You only need one of them to be true. Conversely, if (first_function() & & second_function())) ... the second_function() is skipped if the first_function() returns false. You only need one of them to be false. This can help. Otherwise, just use lots of parentheses!!",
"C does not technically have booleans. However it use an int to represent booleans where 0 is false and any other value is true. # ! a int not(int a) { if (a == 0) return 1; else return 0; } The AND operator checks if both expressions are true. # a & & b int and(int a, int b){ if (a != 0) if (b != 0) return 1; return 0; } The OR operator checks if either of the expressions are true. # a || b int or(int a, int b){ if (a != 0) return 1; if (b != 0) return 1; return 0; } There are some nuances to this. As noted in the text the not operator is valuated first, then the and and lastly or. You can control this using parenthesis. So !a || b & & c is the same as (!a) || (b & & c). In addition the expressions are not evaluated unless needed. So if you write (a & & b++) b will not be incremented unless a is true."
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5nl5zk | Why does that "insert" key that deletes your text as you type exist? | Consensus at work is that it's just annoying, and nobody could think of a way it'd be useful. Is it just a vestigial feature of some sort? | Technology | explainlikeimfive | {
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"It used to be more useful back in the day. Before computers on the market came equipped with graphics processing and spreadsheet capabilities, everything was text based and you would often have to, for example, design your own data tables and such using a combination of spaces and characters like the `|` (pipe). If, for example, you needed to edit a cell in such a table, it was in many ways easier to simply navigate to that point and overwrite the existing text in the cell rather than using backspace/delete and messing with the table formatting. Also, keep in mind that computers originally did not have a mouse for user input; that didn't come until later. So selecting and removing multi-character or multi-word sequences was a lot more difficult. In many cases it was easier to simply type over the existing text characters than it was to spend the time/effort deleting them and starting over.",
"That's the sole purpose of the insert key. To toggle between over type and insert mode. Insert mode being that characters are added without replacing existing characters",
"It's largely vestigal. It's also relatively handy when working with code instead of say a word doc, since usually your code is separated by lines and you can just overwrite and not worry about trucking over your next bit of text. It's a feature that was handier and made more sense in the pre-mouse era."
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5nm6m4 | How would somebody create a new programming language? | Technology | explainlikeimfive | {
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"You would write a program in another language to make it work. The two approaches are: * compiler - reads a file of the new language and changes it to machine code * interpreter - reads the file line by line and executes each command Many modern languages, like java, perl, and python take a hybrid approach to various degrees.",
"At the lowest level, the CPU can understand machine code, which are very simple instructions. You could theoretically write this directly, but it's very tedious and difficult. Instead we have programming languages, and we have a program that will translate something written in a programming language, i.e. source code, into machine code. This is a compiler. When you have compiled source code, you'll have a binary file which you can execute. So, if you want to create a programming language, you make up a bunch of rules for how a compiler should interpret source code into machine code. Then you make a compiler using another language to get you started."
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5nmsa2 | How can someone be lost at sea with all of the technology and satellites we have now? | I saw the post earlier about a man and his daughter who have been lost at sea for about a month finally landed in Australia. Maybe it's because I watch too many sci fi movies, but I find it hard to believe that with all the technology we have now we could not pick them up on a satellite or something. Are we not as technologically advanced with satellites as I assume we are? | Technology | explainlikeimfive | {
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"> ...pick them up on a satellite... Satellites don't have any special abilities to \"sense\" where people are. Most satellites aren't cameras, those that *are* cameras are in use by spying agencies and they cost a trillion dollars. If those lost people were floating around the Indian Ocean spotting them with a spy satellite would be like spotting a tick on a dog from a mile away. Compounding that, the ocean is full of floating garbage. Miles and miles of it. Its not a matter of technology, but scale.",
"Oceans are huge, and most GPS technology only *accepts* information from satellites; it doesn't talk back or relay any information back to the satellites, so no one sees or hears anything. Also, did I mention that they oceans are huge?",
"Oceans are huge, that's basically the answer. A major aspect though is that acquiring temporary use of a satellite costs millions of dollars, something that's not viable for search and rescue. So, helicopters can be sent out to look, but again, the ocean is huge. If the people lost at see bought an [expensive satellite phone]( URL_0 ), they could call someone and give them their location (cell phones would still have a GPS signal).",
"Sci-fi TV/movies paint a pretty amazing picture, lol - they just dial up a satellite, cut to the shot of it spinning into position (cue low rumble), snap a couple pictures, enhance, and oh look! Facial recognition says that's our bad guy :) Most satellite imagery that you see on the news or Google Maps is captured from Low Earth Orbit (LEO) and therefore has a pretty narrow field of view, 8-12 miles wide in the case of the [WorldView]( URL_2 ) satellites. The resolution is 1 pixel per 18inches at best, so detecting a face is out of the question, maybe a body, a boat is reasonable. Imagine trying to find a single flea (and that's ridiculously large as compared to a human, heck even a boat, in a 100sq-miles of ocean) on a carpet square 45ft x 45ft, taking pictures 1-inch by 1-inch, and you can only take a 1-inch wide row of pictures every 90min (on average the time of one orbit around the earth at ~380miles up). It would take you over a month to photograph the whole thing. Let's hope the flea (or the boat) didn't move. Now somebody's going to nitpick my numbers, but I fudged a lot...point being, it's just not practical to visually scan an ocean from so close, and the ones that are sitting at Geosynchronous Earth Orbit (GEO, 22000 miles up) don't have that kind of resolution - they're meant to look for hurricanes, etc. However, [NOAA]( URL_1 ) has been operating the [Search and Rescue Satellite Aided Tracking (SARSAT) System]( URL_0 ) and it has rescued almost 4000 people since 2001, but that only works if the vessel or person is carrying an emergency transponder."
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5no3xz | How do air-conditioners work? | Technology | explainlikeimfive | {
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"A/C uses a gas which is compressed, the heat is extracted from it using a coil and a fan, and then is allowed to expand, and it cools considerably, then a 2nd fan blows air through that coil which absorbs heat and cools the room air. Thats why the outside unit of an A/C system blows hot air, its cooling the compressed gas."
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5no8ph | How do hard drives get bigger in capacity, but physically smaller in size? | And why is there a time delay between the development of hard drives as well? (I.e. why did 500gb hard drives cost so much back then, compared to how much they cost now? What has changed developmentally?) | Technology | explainlikeimfive | {
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"Technology. The smaller you can make the parts that store information, the more you can fit in one spot. For example, imagine using apples as a way to keep track of things when you're counting. Everytime you count up, you move one apple from a bucket on your left to a bucket on your right. Apples are really big, right? So maybe you switch to rice. you can fit a lot more rice in nice neat pile. Which means you can count much higher. Or if you're writing, maybe you switch from a #BIG FONT to a normal one. Because why waste so much space? Over the years, we've been getting better and better at storing stuff. It's hard to list all the changes, there's been so many. Using different materials, maybe you can make smaller bits, the thing we use to store the data. These days, they're down to 10s of nanometers. So you need to make these little pieces, consistently, and they need to work repeatedly for years. That's hard! No only that, you need to be able to read them. Technology has gotten better and better- including using things like lasers to read/change the bits. > And why is there a time delay between the development of hard drives as well? Because it takes time to develop new techniques. Over time, you have people working on finding new designs, trying new things, gaining experience on what works, and what doesn't. If i tell you to build a house, you probably wouldn't do a great job, right? Maybe you could rig a tent. But if you get training to be a carpenter (or just spend time trying new things), you'd be able to build a cabin. But you probably don't know how to build a good cabin off the top of your head. And with better harddrives, you can't just go to school- no one else has made them yet either! > why did 500gb hard drives cost so much back then, compared to how much they cost now? 2 main things: How easy they are to make, and how many are sold When a technology is brand new, it usually isn't the most efficient design. Over time, companies learn how to use materials that do the job better, or are way cheaper. The other thing is, the more you sell, the cheaper most things are. Say you need a special piece of equipment to make the drive, like a press. If you only sell 100 copies, you need to make enough money back to cover the cost of the press+labor+profit. If you sell 100000 copies, you still want labor/profit, but maybe that one press gets reused a bunch of times. A lot of the techniques/machinery are extremely specialized, and one of a kind at first. It's not uncommon for a single machine to cost millions of dollars.",
"The main differences are the configurations hard drives store data, and the actual hardware. Floppy disks, ssd's, and any sort of drive store there data with ones and zeros. However, floppy disks and cassets worked by keeping physical copies of the ones and zeros, almost like a punch card. Now, they are all stored in imcrochips, which can access trillions of ones and zeros in no time. Over the years, we have created more physically capable chips to store more data, but are still getting smaller. TL;DR, the way we have stored information on hard drives and their sizes changed dramatically when we switched from physical data to microchips."
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5npoyi | Why is 'foo' and 'bar' used so much when explaining programming? | Technology | explainlikeimfive | {
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"It's just an easily-recognizable convention to indicate that \"something goes here, and the name itself is not important, so you can avoid trying to determine whether the name is significant — it's not\". \"x\" would be similar in some mathematics as the stock fill-in-the-blank. Once a convention is established, changing it is confusing, so the best term to use for everyone writing new things is the existing one. Wikipedia has a [more detailed history that tries to trace out possible etymology]( URL_0 ), but any other term could have done as well.",
"It appears to have originated from the military acronym FUBAR - but no one know for sure. It was popularised as a placeholder variable by MIT during the 1960-70's. Since then it's just become a bit of a meme, in the same way that all beginner programming tutorials print \"Hello World!\".",
"And on the topic of placeholders in programming, Swedish programmers will input Räksmörgås (shrimp sandwich) to make sure a program handles our umlauts correctly.",
"Foo and Bar are the most common *metasyntactic variables* used by Anglophone programmers. I suggest you look at the Jargon File, a late-70s compilation of hacker slang: URL_1 URL_0 The entry on 'foo' traces it back to The MIT (model) Railway Club, which actually contributed a number of terms to the lexicon.",
"A lot of this responses are misinformed, probably because they don't program, but answers like /u/nounhud are good. People focusing on FUBAR are wrong. While it may share a root and phonetically they sound similar foo and bar, as seen in programming examples, is no reference to how messed up some code is such as /u/Hickorywhat is describing.",
"foo, bar, baz, qux, quux, garply, waldo, fred, plugh, xyzzy, thud ...if you want to keep going :)"
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5nqyt3 | What is a "Windows X System" in relation to operating systems? | Also are the terms remote X session and SSH related terms? What do they mean in this context? Thanks! | Technology | explainlikeimfive | {
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"That's X Windows System, not Windows X System. It is also known as X11 or just X. X is basically the windowing system used by UNIX and UNIX-like operating systems. It's been around since 1984. Unlike more popular (nowadays) windowing systems like Microsoft Windows and Mac OS, X is just a basic framework. It provides a basic GUI and, well, windows and a mouse cursor, but you need *other* software to do stuff like put borders on the windows, move them around, etc. This is known as a Window Manager. The advantage here is that you can customise the heck out of your GUI by using the window manager that *you* like. Another *major* difference is the client-server architecture. X runs as a server, and clients connect to it. Basically, if you run X on your machine, you have something that can display windows. To actually *get* these windows, you have to run a client (basically, a program). For example, you can run a browser like Chrome or Firefox. Rather than displaying their data directly, they connect to the X server and have the *server* display the data. The advantage here is that you can run X on your own computer *and all other applications on different computers*. If you think about the UNIX mentality, this makes a lot of sense, especially in the Olden Days when people used fairly weak terminals to display stuff, and had big powerful servers to run applications on. It *also* means that I can run any flavour of Linux I want on my desktop, and use any *other* UNIX-variant to run my applications. Now back in the olden days when we had many different flavours of UNIX running on many different platforms, that was a lot more impressive (I could use a cheap x86 desktop running Linux, and run my applications on a $100,000 SGI Origin cluster). It also meant is was *trivial* for me to display a window on *your* computer. It used to be *more* trivial when everyone was connected directly to the internet, but if we're on the same network it's still remarkably easy. This relates to SSH in that you need to connect to the remote system in order to launch your application. Again, in the Olden Days we'd use telnet or rlogin, which are immensely insecure protocols. Those have all but died out with ssh becoming ubiquitous, and is virtually exclusively used for connections between systems."
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5nrnon | What is so groundbreaking about the Amiga? | Technology | explainlikeimfive | {
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"For its time, it has very advanced graphics capabilities. It also was one of the first PCs to multitask. It used to be that computers could only do one thing at a time. If you want to copy a file, that is all your computer would be doing until the copy was done."
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5nsjne | Why is it bad to quickly restart an air conditioner compressor? | Technology | explainlikeimfive | {
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"The air conditioner has a motor which compresses the gas hence it is called the compressor. If you start the compressor after a period of being off then the electric motor, the compressor, starts against no load. It does not begin pumping against a compressed gas. It is easier for a motor to start against no load. If the air conditioner was running then there is likely to be compressed gas still in the system. That is why the compressor is there. The compressor starts from zero speed against a load just as you might begin pedaling up a hill on a bicycle. Electric motors draw a large current getting started. They will draw even more when starting under a load."
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5nsvbq | Sometimes my phone's change with go from say 3% to 7% if I leave it alone for a long time. Is it actually regaining charge? | Technology | explainlikeimfive | {
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"dce1oxy"
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"text": [
"Your battery app calculates the remaining battery based on the battery power currently being used (mV) and your usage since it was fully charged. That's why you can generally do calibration to correctly measure the current battery status and range of it. Usually, if we ignore very little variations in the battery power, it goes down. So either your phone's forecast was wrong, or if the battery usage is lower than the expectation, in which case the battery level showed on your screen will increase a little. Hope it was clear, English is not my native language, sorry about that."
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5nt14e | Why do capacitors make that high pitched sound? | I have 3 old camera flashes, All of them make a noise when charging up, Why is this? And why are modern ones silent? | Technology | explainlikeimfive | {
"a_id": [
"dce3knl"
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"text": [
"It's probably not the capacitor, it's the transformer. Older cameras generate a high voltage to get a bright flash, and that voltage is generated through a transformer/capacitor circuit. The whining is caused by [magnetostriction]( URL_0 ). As the magnetic field rapidly changes in the transformer, the materials expand and contract a bit. This sets up a high frequency vibration that you hear as a whine."
],
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5nt308 | What is the logic behind AI in strategy games such as Starcraft or Xcom. | I can understand something like a basic chess AI using a simple net points (Might be the wrong term but I'm mostly self taught, sorry) system but I'm having trouble figuring out how to get an AI to consider strategy past that. Thanks. | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"In starcraft, each unit has a \"counter-unit\". At the highest difficulty, an AI will likely have one of its workers or cheap units in your base, watching your build, while simultaneously building the counter to what you have. This is how it decides upon the macro side of the game. For the micro (individual skirmishes or fights), each unit has a given value to variables such as damage, range, and speed, and the AI can make a decision to fight, run, or a combination of the two based on the units it owns and the units you own in each respective fight. If you think about it, starcraft isn't a hard game to learn from a \"what-to-do\" standpoint of what you should be building and which fights to pick and which ones to run from. The hard part of the game is getting your ideas from your head to the game while managing everything simultaneously, but an AI can do this all instantly, making it quite difficult to best the hardest AI's. All it has to do is simply separate the big picture (buildings and units) from the small stuff (fights and movement). Source: High master rank in starcraft with lots of bot games played as well."
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5ny114 | why do light bulbs only seem to ever go out when turning them on instead of while they're already on? | Technology | explainlikeimfive | {
"a_id": [
"dcf3zxq"
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"text": [
"when you turn on a conventional lightbulb it heats up in a flash, which stresses the filament. once it's stabilized at its new temperature it's generally fine, but it does happen that they burn out while on, usually if left on for a long time or if there's a power fluctuation"
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5nyg70 | When you see stories like, "12 year old invents cheap alternative to a significant medical/military/household product", what actually happened? Were they receiving some uncredited assistance or are they actually just child geniuses working alone after school? | Technology | explainlikeimfive | {
"a_id": [
"dcf7i1r",
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"text": [
"It's almost always FAKE NEWS. The rest of the time it's a reporter without much expertise in the fiend that's unrealistically impressed by a good science fair project. If you look at genuine science fair awards, [like these Intel ones]( URL_0 ), you'll see the same kind of small, incremental breakthroughs that you see from regular scientists and engineers. These kids are older, 16-18 usually, and they got really deep into a narrow problem. They're probably really geniuses.",
"I do believe that there are actually child geniuses that come up with cool ideas. But also that there are a tonne of kids who are helped (significantly) by their parents. The thing with coming up with alternatives is that you're working on existing ideas. Also, the thing of being a kid is that your time is valued as free. So let's say ACME wants to produce a water filter. They set up a team to design this water filter. They have to make a a list of requirements, specifications etc. Well, after a while they have this. So they can set to work, designing a new filter and subsequently testing, redesigning, testing some more, tweaking the design to be suitable for (mass) production and done, they have a filter. This filter already costs money because it had to be researched, concepts had to be tested and the best concept was further developed into the final product. The final product is not yet ready to be sold since it has to be tested first to see if it is safe for consumers, even more money is being spend here. So when the product finally hits the shelves it has to recoup all those R & D costs, production costs, overhead and a profit margin, because ACME is a company after all. Now along comes a bright kid with noble intentions. They set out to work in their spare time. They do some research and find an idea that they like and want to often improve upon. So they do some work, some testing, use household stuff, because that is what most 12 year old kids have to their disposal, and find a way to achieve the same result. They show this result to the world and present the cost, which consist only of the material costs. The kid doesn't include all the hours spent on it, because it was a hobby. Doesn't have overhead, since their parents pay for housing, food, internet, etc. Doesn't have a profit margin because they want to better the world and doesn't have product testing costs because it is a hobby project. Don't get me wrong, these kids are very bright. But a lot of costs from their final project are hidden and a lot of research is done already."
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5nyjec | Why arent SSDs and SD cards the same size even though a lot of them can hold the same amount? | Technology | explainlikeimfive | {
"a_id": [
"dcf93qk",
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"text": [
"An SSD is very much different from an SD card. SSD's, SD cards and phone internal memory for that matter uses the same NAND flash chips. However a fundamental difference here is the controllers. Imagine a room in which you want to fill in stuff and it has an automatic door. In layman terms a controller is like an automatic door. The bigger the door the more you can fill into a room at a time. But the bigger the door the more power you need to open and close it. This is exactly what happens. An SD card is used in small devices like phones, tablets and cameras. There's only so much power that a phone can supply with its tiny battery. There is simply not enough power to feed an SSD. If you ever open an SSD you will notice that the main memory is tiny. Its about the size of an SD card. But what uses up all the space is the motherboard. That has the controller and other components. Also, who told you they have the same speeds? An SD card barely has any speed. An SSD can do gigabytes per second while an SD card struggles with 100mbps. Source : Took part in the Mumbai Hackathon 2016. SSD speedup and SD card data security was my main topic. ( so I know some shit here and there)",
"SD cards and SSDs dont provide comparable speed. Good SD cars are around of 10MB/s while SSDs are around 500MB/S sequential bandwidth. SSDs also last longer their mean time between failurs is around 1000 times of a Sd card which can already fail at around 1000 write cycles. And third access time/ latency. SD cars need around 1ms for random accesses (or 1000 IOPS) while comodity SSDs already provide 100.000 IOPs So SD cards are smaller, cheaper in capacity but are not as fast as SSDs in bandwidth, latency and durability.",
"They aren't the same speed, SD cards typically read at 30MB/s based on typically using USB connection paths. SSDs can read from 500 to 2000 MB/s because they connect via SATA or PCI which is way faster. Beyond that, SSDs are the size they are to support replacing a magnetic hard drive as a swap in part, and to allow for the controller hardware to do things like spread writes around for longevity. So mostly, it's bigger because that is what we are used to in computer and notebook cases, and because SSDs have controller hardware, not just storage."
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5nzohm | how HDD and flash drives store data without being connected to electricity . | i always took it for granted but never knew how it works , can someone eli5 how the data is kept in harddisk drives ,etc... after its not connected to a power source ? | Technology | explainlikeimfive | {
"a_id": [
"dcfgqwv"
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"text": [
"Differently. HDDs store data in the polarization of a thin magnetic media. The coding is along the lines of if NS then that's a 0 and SN is a 1. Flash storage uses electrons stored in a tiny capacitor. Lots of charge = 1 and no charge = 0."
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5o19ey | How does noise canceling work, and can it hurt your hearing by actually adding more sounds and decibels to your ears? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"A sound wave can be represented by the lower image for simplicity: URL_0 Noise-cancelling equipment is able to produce a sound that creates a 'peak' where the heard wave is a valley, and a 'valley' where the heard wave is a peak, as in this diagram (ignore titles) URL_1 This results in no sound being heard, because waves that are perfectly out of phase will cancel themselves. Noise cancelling equipment eliminates droning white noise, not loud noise. The sound itself wouldn't damage your ears, and neither will the equipment that can cancel the sound. Only loud sounds can hurt your ears, so wear ear protection where there is loud white noise, not noise-cancelling equipment",
"The other responders explained the first part of your question better than I could, so I'll defer to them. I'd like to address the second half about whether or not adding more sounds and decibels can hurt your hearing. While active noise canceling headphones add sound waves, they do not increase decibels to your ears. In fact, they decrease them. Think of sound waves like ripples in a pool or pond. The height of the waves (amplitude) is how loud the sound waves are. So if you have something at one end of the pool causing waves 10cm high that might represent a loud sound. Now let's say you have another mechanism that creates waves, but times them in such a way that it adds a peak when the other wave is in a trough and adds a trough when the other wave is a peak. The peaks and troughs of both waves cancel each other out and you get waves with smaller amplitudes. You added waves, but decreased the height of the original wave through interference. This is how noise canceling technology works.",
"Sound waves are sinusoidal. Think of a [sine wave] ( URL_0 ), it varies between a peak and a valley. Noise cancelling produces a sound wave that is exactly the same, but 180 degrees out of phase... meaning at the same time that the original sound produces a peak, the noise cancelling system produces a valley and instead of a valley, it produces a peak. When you combine the two waves that are 180 degrees out of phase, the amplitude cancels out to zero. It's the same as how adding +1 and -1 = 0. Does it hurt your ears? No, because the level of the sound is actually reduced. This isn't tricking you into thinking that it's reduced, it really is. The amplitude of the noise reaching your ear drum is much lower, which is why you don't hear it."
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5o1bq8 | How does the postal service machinery know the correct amount of postage has been put on via stamps? Especially with old postage stamps, or a many small currency stamps. | When I put a stamp on the envelope, how does the machinery know the correct amount / how much postage has been placed on the envelope? Is each stamp micro-printed with a code the machinery can read as the value, or does the machinery have a database of every stamp and it's proper value? And what about small packages with stamps (like books) where there's a total of like 12 stamps between forever stamps and 2 or 3 cent stamps? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"The usps is very outdated and playing catch up they aren't good at catching it and rely on the workers a lot to catch it . They use to be really terrible and I know people who would ship out dozens of packages daily all at 1 lb no matter what and rarely ever had issues for years . Fedex use to check 10% of packages for accuracy and now I am not positive but it might be 100% of them . Conveyor belts , cameras , sensors , scales barcodes it all gets processed now with lightning speeds at the distribution centers . Watch any Fedex or ups warehouse video or documentary online and you can see how crazy they are . Tons of people still scam the post office all that happens is you get a \" postage due\" notice unless it's on a massive wide scale then maybe they will investigate and prosecute . Fedex and ups just bill you no matter what depending on weight and dimensions ."
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5o1um8 | Why is it impossible to decrypt something after it has been encrypted to md5/bcrypt/etc? | Technology | explainlikeimfive | {
"a_id": [
"dcfzsnz"
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"text": [
"Because those aren't encrypting functions. They're hashing functions. Unlike an encryption functions, hash functions cause you to lose information when you do the transformation. The simplest operation that exhibits this property is modulo division (taking the remainder of a division operation). If I have 12 mod 5, the answer is 2. But, given just the numbers \"5\" and \"2\", there's no mathematical operation you can perform that will result in you getting 12. Now, modulo is a pretty simple operation, so you can see pretty quickly that the numbers 7, 12, 17, 22, and so on will all match this problem. With the password hashing functions, there's still multiple solutions that will give you the same hash, but the math is complicated enough that the guess-and-check method of trying to find a match for a given number will take centuries."
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5o2ues | Why do most news websites currently have a "Click to expand article"/"Read More" button on mobile? | Technology | explainlikeimfive | {
"a_id": [
"dcgbdrl",
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"text": [
"Lots of reasons: * It allows the page to load faster in order to get all those ads in. * It validates the interest in the article that justifies the rates charged to advertisers. * Enables the page to fit the horizontal screen of a lap top. * It enables them to switch ads in order to get more advertiser exposure. * Enables the memory required to fit the limited capability of a smart phone. * Enables them to offer an online subscription.",
"Allows them to load more ads before the end of the story So basically they get more ad views before you realise you have to click the read more button.."
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5o3j0f | how do 64kb demos work? How is a video generated from such a small file? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"My thesis supervisor was interested in these demos ([here's one he made]( URL_3 ) and [here's]( URL_1 ) his thesis on it, though it's in Czech, but there's a lot of pictures) and he told me a little bit about them. Here are the main things: - The demo in not a video, it is a program that renders the animation. Program is small because it is just a small amount of instructions. - Procedural generation: Data, such as textures, is what takes up absolutely the most space in programs. Here instead of having the data embedded in your program you create algorithms that generate all the data, somehow randomly but within certain rules. Algorithms are extremely small, even if they are complex, because they are in result just a few instructions, of which each only takes a few bytes. These algorithms can however generate huge amount of data - textures, 3D models, music, everything. For example you can generate so called [Perlin noise]( URL_0 ) and use it as a heightmap for terrain. If you're more clever, you can make images like [these] ( URL_2 ) (these are from my bachelor's thesis on procedural textures). - Getting rid of any unnecessary stuff: In normal programs a few extra kilobytes usually do not matter, so most programming tools add extra layers to programs to make the programming more comfortable, faster, safer etc. If you want your program to be small however, you can give up these advantages and save memory. You can do this by using a low level programming language (assembler, C, ...), using special programming styles, telling the compiler you want to optimize for size, giving up platform independence etc. - Some data, such as camera movement, can be embedded in the program since they are very small. Camera movement can consist only of a few keyframes and the program then smoothly moves the camera between them. Camera keyframe may look like this: time (4 bytes) camera position (x,y,z = > 12 bytes), camera rotation (x,y,z = > 12 bytes). This is a total of 28 bytes for each keyframe. If you have 20 keyframes, your whole camera movement is encoded in 0.5 kb. - Compression: to make it even smaller, everything is compressed in the end."
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5o3tlu | Why are there different versions of Windows? (ie Windows 10 Home, Pro etc) | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Basically Microsoft could just sell the same product to everyone, but they want to make as much money as possible. They can't ask home users to pay the same high prices as business as many wouldn't want to pay that much and they can't just lower the price for windows for everyone to the same low price that every home user can pay. In order to maximize profits they want to sell the same product at different prices to different people They want to sell it cheaply to those who wouldn't buy it if it was more expensive and they want to sell it for a higher price to those who can afford it. So far so good. But how do you do that, you can't ask all customers to tell you how much they are able to spend before you tell them the price. If you offer it cheaply everyone will buy it at the cheapest price. To make sure that the customers with money (mostly businesses) buy windows at the more expensive price they split the product up into multiple versions (called editions or **SKU**s). They took the cheapest version and removed all sorts of features that you normally wouldn't need as a home user. Normal home users don't really need to domain join feature of windows so that gets excluded from the cheapest version. It is no loss for home users but businesses who need it will need to buy the more expensive version. Other functionality that you may not see in the cheaper editions of windows are stuff like drive encryption (Bitlocker) and similar stuff that are mostly needed or wanted by businesses. They also introduced all sorts of arbitrary limits that won't matter to normal users. Windows 10 Home edition for example only allows a maximum of 128 GB of memory, which is far more than any normal user would ever need. If you want more you need a more expensive version of windows. This was actually much more noticeable with windows 7 where \"Windows 7 Starter\" only allowed 2GB of RAM, \"Windows 7 Home Basic\" 8GB, \"Windows 7 Home Premium\" 16GB and \"Windows 7 Ultimate\", \"Pro\" and \"Enterprise\" allowed 192 GB of RAM. So they removed features and included artificial limits to ensure that people spend as much as possible for them on what is actually the same product. With Windows 10 at least Microsoft has limited the number of different editions quite a bit, there used to be far more in previous versions.",
"The simple answer is that it is making Microsoft more money and it is giving you more features. Although you do have to realize it is also costing Microsoft more money to give you those features. You have the obvious development costs, but a lot of features they have to either license a patent or the actual software from another company. The earliest instance I can think of this is HyperTerminal."
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5o6cww | How do Speedometers work? | I have a rather large truck with large wheels. I have always assumed I travel faster than other vehicles because of how big my wheels are. The other day my girlfriend was driving behind me and I was only going 55 mph while she told me she was going at least 70 mph to try and keep up with me. How is it that I never get a speeding ticket although I am going faster than most vehicles on the road? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Speedometers measure the speed of a vehicle by using a magnet attached to the vehicle's transmission through a series of gears. As this magnet spins it interacts with the speedometer needle and pulls it a certain amount depending on the speed of rotation of the transmission. speedometers must be calibrated so that the amount the needle is pulled accurately reflects the speed of the vehicle and the difference in speed you describe is most likely due to either your's or your girlfriend's speedometer being calibrated incorrectly. Tire diameter can affect the speed of your vehicle without changing the measure speed on the speedometer, so if you have much larger tires and in particular if these were not the original size of tires of the vehicle this could cause the reading on the speedometer to be incorrect For completeness: Electronic speedometers work in a similar way, just the reading is transmitted to the speedometer by wiring from the transmission instead of mechanical gears"
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5o6lhu | How do we create "easy" AI in video games? | I understand how artificial intelligence works in general, but my question is how do developers make "easier" AI in video games? AIs that make mistakes and can be easily outsmarted or outperformed by a human? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Depends on the game really. In games like chess you can adjust the difficulty by telling the computer to not look so far ahead. In games like FPS's it's actually hard to make a good playing AI, movement and tactic-wise. They try to make the AI as good as possible here. Aiming-wise, on the other hand, AI could be made unbeatable of course, so they can for example penalize the AI's aim by randomly \"poking\" it in a certain direction, making it wait for a while before shooting to simulate human reaction time, etc. In games like Warcraft III, they actually had to make the hard AI cheat by mining more gold than the player, and still if you were good, you could beat it easily. So I really think that the problem with AI being too good is only when it comes to precision, in which case they simply penalize it with randomness.",
"Most Game AI just detects certain events that occur and then chooses a set response from a list of responses. For example, a monster can trigger some logic when their HP drops below 20% to randomly either 1) Become enraged and charge at the player or 2) Run away and cast a self healing ability. If this was an easy difficulty maybe this can be tweaked so that the monster runs away more often or maybe the healing is not as effective. Maybe the monster has less HP overall or has a lower attack rate. This isn't what computer scientists would consider to be real AI. Real AI in games such as chess would look several moves ahead and anticipate the opponent's response to each of the possible moves and will choose the move that will put it in the best position. In this case lowering the difficulty will limit how many moves ahead the AI can look."
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5o7mab | Why are circuit boards colored green as opposed to other colors? | Technology | explainlikeimfive | {
"a_id": [
"dch7x5s"
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"text": [
"Nowadays you can find boards in many other colors other then green (black, white, red, purple, etc). As for why it has been green since forever there are some theories I found: Military requirement Consequence of the fact that originally the base resin was brownish yellow and when mixed with the hardener (muddy brown) you got green Best contrast between the solder mask and the white legend (the background and the text on the board) Most visible color to the human eye If I had to guess it's probably a bit of all of the above and companies stuck to the color until there was more demand for some variety"
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5oah3o | Solar panels. How do they work? | Technology | explainlikeimfive | {
"a_id": [
"dchu1xn"
],
"text": [
"The sun creates these things called *photons*. These photons are little packets of light and energy. These are ejected from the sun trillions and trillions of time per second. When photons hit things, they can give up their energy to them. That's why light can heat things up. Solar panels take this energy and store it. The main mechanism is called the *photovoltaic* effect. Solar panels have a crystal panel that the light shines on, and inside there is a lot of circuitry which is connected to a battery or energy storage device. The crystal panel is made up of atoms. Atoms are composed of their cores, and the electrons which orbit them. The cores, assuming they have at least one proton are positively charged. To even out the charges so the atom is neutral, negatively charged *electrons* surround them. They \"orbit\" the atoms at different energy levels. Getting into this area any further ultimately leads to quantum mechanics and things get a little too wishy washy and mathy to do a good ELI5 on it. If a photon hits the orbit of an electron, the electron could take that energy from the photon and *excite* and go up an energy level. Now the solar panel has *captured* the energy from the sun. This happens all over the solar panel. This is where the *photovoltaic* effect kicks in. The crystal panel's exposure to light (because of how it can capture energy to excite electrons) causes a *voltage* change, and can cause an electric current in the circuit. This causes energy to flow into a battery and we can store it for later. Edit: Thanks for the suggestions /u/TBNecksnapper"
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5oapam | Is it okay to leave your phone (or other electronics thay require charge) plugged in and charged overnight? | Technology | explainlikeimfive | {
"a_id": [
"dchxbhe"
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"text": [
"No, it actually prolongs the life of the battery. Once the battery is full, the charge circuit will cut power to it and not charge it again until the battery voltage drops by some amount. However, while your phone is plugged in, modern phones will not draw any power from the battery and rely purely on the external power. This basically means your battery is not being drained for those remaining hours. Battery lifespans are typically measured in the number of full charge-discharge cycles, so by keeping your phone on charge for a few extra hours a day, you're saving those hours from the lifespan of the battery."
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5oebrg | How do computers go from physical parts to computing languages? | Confusing title, I know, but what I'm asking is what is the link between the physical aspects of computers, such as soldering a circuit board to typing in programs like java? What are the levels in between physical components and digital programming? | Technology | explainlikeimfive | {
"a_id": [
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"[Here]( URL_0 ) is my answer to a similar question, if it helps you.",
"* transistors/vacuum tubes/relays - electronic switches that can be opened or closed electronically, and used to control other switches * logic circuits - a handful of transistors can build a logic circuit, usually with two inputs on one output...an AND circuit's output only has current if both inputs do, an OR circuit outputs current if either inputs do * a handful of logic circuits can make a digital circuit...a flip-flop is a simple memory circuit that can store one bit, an adder can add multibit values together * those simple digital circuits can build more complex digital circuits, full fledged memories and mathematical and logical components * you can build a CPU out of complex digital circuits, a memory that contains a list of instructions, and a control unit that activates the right component based on that instruction, the essence of machine language * once you have machine language, you can use it to create higher level, more human accessible programming languages"
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5oexio | What exactly do artist do in video game design with the programmers to make the game complete? | Technology | explainlikeimfive | {
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"Artists make everything you see on your screen. Animators make all the things you see on your screen move the way you see them move on your screen. Programmers write code that tells your computer when to play what animation when you press a specific button.",
"Artists provide the 3d renders and models that respond to the programmed code. A programmer writes a code \"if W is pressed: model A does X action\" the artists create the model and animate the action that occurs; as well as they create the landscape that the model walks on."
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5oflgs | Why commercials have a long and short version. | Many times I will see an ad for the first time and it is 30 seconds or so, then in the coming weeks that commercial will be cut to a shorter version, maybe 10 or 15 seconds. Sometimes it even has shots that weren't in the original. Anyone in advertising who could shed some light? | Technology | explainlikeimfive | {
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"Yep, it is a specific marketing strategy aimed at regular tv watchers. They start running a long commercial (1 minute) that hopefully does a really good job of being remember by the audience. This if often not hard because 1 minute commercials often stand out because they are so long already. They will run these for a few weeks, and then cut it down to a 30 second spot. This has the affect of you already recognizing the commercial, thus it doing its job, but costing less money as commercials are charged by run time and audience size. Sometimes they will even reduce it to a 15 second spot after that. It is just a way to maximum people remembering the commercial while minimizing the cost."
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5oh1is | How exactly does a computer execute a program? | Okay, so I understand how computers work, the basics, bla bla bla, that they are comprised of binary, dividing complex problems into millions of simple additions/ subtractions, and I understand how a computer functions on a bunch of commands etc. What I'm struggling with is how a command is actually executed, and how memory can program the computer into a machine of that specific task. I'm sure it's just because I'm overwhelmed with the shear complexity of modern computers, so let's make this simple: Say I had a really simple, homemade even, computer. How would the computer execute a program that allowed me to input a calculation such as '73+9'? How is it that this stored binary can completely reprogram a computer to do this? | Technology | explainlikeimfive | {
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"At the very basic level, I think what you're asking about is \"machine code\". Let's imagine a basic computer. It might have a few different instructions: - INPUT - read a number from the user, and store it in a \"register\" - OUTPUT - take the number in the register and show it to the user - GET - get a number from memory and store it in the register - PUT - get a number from the register and store it in memory - ADD - get a number from memory and add it to the number in the register. This is basically the way real computers work, although they have much more complex sets of instructions. But with this basic set of instructions, we can write the following program: INPUT - get a number from the user PUT 100 - store that number in memory location 100 INPUT - get another number from the user ADD 100 - get the first number, and add it to the second number OUTPUT - show the answer to the user What we've got here is \"assembly language\". To turn this into machine code, we need to know a special code that's associated with each command. Let's imagine our simple computer uses these codes: - INPUT: 0 - OUTPUT: 1 - GET: 2 - PUT: 3 - ADD: 4 With this knowledge, we can take our program, and turn it into a string of numbers: 0 - INPUT 3 100 - PUT 100 0 - INPUT 4 100 - ADD 100 2 - OUTPUT That string of numbers (0, 3, 100, 0, 4, 100, 2) makes up the machine code program. Each number is stored in a memory location, read in turn, and then used to decide what to do. If you want to play around with this idea some more, then have a look at [Little Man Computer]( URL_0 ), which is designed for teaching exactly this subject. It uses a set of instructions which is slightly bigger than the one I've used (but still much smaller than a real computer), and once you learn to use it fully, it can actually do some pretty impressive things!"
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5oj06y | Why do drives on PCs start with C:\? Where are A:\ and B:\? | Technology | explainlikeimfive | {
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"Back in the day, PCs didn't have hard drives. They only had [floppy disk]( URL_0 ) drives. A common configuration was to have two drives, usually one 3.5\" drive and one 5.25\" drive, so they were designated A: and B:. So when hard drives became common, they were given the next letter - C:. A lot of programs relied on having the main hard drive at C:, so it became the standard, and remained so even long after floppy disk drives became obsolete.",
"This is the first question I've seen on here that really made me feel old. Growing up at a time when computers suddenly became accessible to the public, the idea of why the drives were named as such was obvious and clear. This stuff is happening way to much lately. I'm becoming an old man. Pretty soon making jokes about a floppy drive will be like seeing pictures of little kids long ago pushing a hoop with a stick down the road. A relic from a bygone era that is regarded with dismissive amusement from those who came so much later.",
"The A and B are reserved for floppy drives. Older computers didn't have hard drives and used a floppy to hold the operating system (A:/) and another to load and save data (B:/). Once hard drives came about, they were relegated to the C:/ drive and it has been tradition since.",
"I feel old. But yeah, there used to be A: and B: drives. I think my first computer had the 3.5\" as the A: and the 5.25\" as the B: Then hard drives came out and became the C: Then CD drives became D: (which DVD and BD drives kept since they kind if replaced each other)",
"Another answer is due to the limitations of the industry standards. You could fit a maximum of 2 drives (primary, secondary) per cable. Primary/Master and Secondary/Slave were set by physical jumpers. The floppy cable could support A: and B: The primary IDE cable, which connected your hard drive and DVD drive, could support two maximum - C: and D: The primary hard drive on the PC was therefore C: Standards like SCSI could support many more drives (set by jumpers). Modern SATA cables only support one drive."
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5oj5qi | Why are the numbers on an analog radio dial irregularly spaced? | Take [this dial]( URL_0 ) for example. The 60 and 70 are just as far apart as the 100 and 130. Why does the dial need to travel just as far to span 100 kHz as it does to span 300 kHz in a different part? | Technology | explainlikeimfive | {
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"Actually it's not logarithmic, it's closer to a 1/x relation since what you turn is not a resistor, but a variable capacitor. A capacitor and an inductor are used in the tunning circuit attached to the antenna. But log scales are indeed used in frequency plots since it better represents the behavior of systems.",
"Behind the dial is a resister that connects between where the needle is and the input antenna. A resister coil adds resistance in a linear state, in order to have the printed scale show what frequency matches for the adjusted antenna length, the scale is printed in a logarithmic scale. Most phenomenon involving waves (sound, light, earthquakes, etc.) work in a logarithmic progression. A simple explanation is that for every 10x increase in a log scale, you always move a specific distance on a linear one. The actual scaling can be any number, but 10 is easy to demonstrate. So to go from 10 to 100 takes 1 inch on the scale. Going from 100 to 1 000 takes another inch 1 000 to 10 000 takes another inch The measure of distance would be from 1 to the number measured. The dial scale does not go down to 1 so you do not see the actual progression from the beginning. Edit: changed description of linear motion from multiplier to step size.",
"It's got to do mostly with the physics of how the tuner works. Most old school tuning knobs adjust a capacitor or resistor (electrical components) in order to change the frequency that your antenna picks up. We find it pleasing to have linear scales (consistent spacing) for the frequency that is being picked up, but it is hard to make resistors and capacitors that adjust linearly. Because it's cheaper to just use resistors and capacitors that don't adjust linearly, the scales on old school equipment are often nonlinear and based on the what components were used in the circuit. However as components became cheaper over time, and the market had an increase in demand for user friendly electronics, aesthetic design became more important that creating the circuit in a cheap manner. Engineers went through an obsession with creating smooth, consistent, linear adjustments for everything. Now volume knobs, tuners, equalization knobs are almost all linear in order to be more intuitive to the user.",
"It's a logarithmic scale, not linear. It's actually driven (in part) by the physics of how the radio circuit works."
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5ojn69 | When someone talks about rendering a video, or an animation, what does that mean? And how would not rendering it affect it? | Technology | explainlikeimfive | {
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"Let's compare video editing to building a car. So you're editing your video, but really it's a collection of parts. Multiple footage clips, effects like color correction, etc. The computer is able to tell you that \"yes, these parts put together make a car\" but rendering is where the parts actually get put together and consolidated into one piece. It's a little more complicated than that I think, but ELI5. If you try to play your video/move your car without rendering, the smoothness really depends on if your computer is strong enough to pick up x amount of parts at the same time. Rendering is like putting some of the car together so it can drive a little smoother.",
"Think of \"rendering\" as a painter painting a still image. In an animation/video, the computer renders/paints each frame of the video. If you do not render it, it would not exist.",
"Rendering a video and rendering an animation are two completely different things. To produce a 3-D animated movie, you actually have to do both. Rendering an animation is taking the 3-D scene the artist works with, and computing what the end result would look like. The artist isn't working with the whole thing, they are often using a simplistic lighting model and the final render actually traces out paths of light and how they reflect and refract and absorb across complex objects. Oftentimes there are also physical simulations being rendered. Animators don't model what water looks like, they just have a water simulation that needs to be processed by the computer to figure out what the water should be doing and what it should look like. URL_0 This video is an example of what artists actually work with when making the movie (with glitches, obviously). See how the models are simple with no textures and simple lighting? That all gets added in for the final render.",
"Rendering takes all of the different assets that may be in a video (clips, audio, etc.) and orders them and is more or less a set of instructions...I.E. \"draw a pixel at this location with this color and play a sound\" instead of \"find the sound and video assets in storage, put it in RAM, run calculations on it THEN draw on screen/play sound.\" Videogames, conversely (for further illustration), are rendered at runtime. Since the character could be anywhere on the screen, particle effects could or could not need to be drawn on the screen, sounds could be true or false, obviously it's not going to be pre-rendered because we don't know what's going to happen yet! Thats why you need a good graphics processor for gaming and video rendering, and why you don't need much processing at all for playing even 4k movies.",
"Rendering means having a machine draw each frame (picture) used in the video. Not rendering it means it would be blank.",
"The other aspect of it is that generally when we think of rendering we are also talking about packaging the video elements into a file that is able to sent and played by others (like a .mov or .mp4). Unlike when you are editing it, these are self contained files with all the parts (footage, effects, sound, titles) baked into each frame so that youtube or whatever can play it. While editing the video, the parts are all being pulled from their locations on the hard drive and the computer processors are temporarily configuring them in a way that you can preview it. Or in the case of an animation the computer is \"drawing\" a model based on what you created. This allows you to make changes and see them instantly since the computer will have to redraw the image again either way (think of how a video game would function). But this takes a lot of computing power and so may play slowly or at a reduced resolution until rendering. Also the file will probably only be usable by that particular animation or editing software. Once you are finished, rendering allows the computer to take all the parts and calculations and \"bake\" it in. Basically, instead of drawing the image it instead is just taking what you as a viewer sees and putting that into a digital video file format. Another metaphor might be a simple modeling clay figure. You mold it with your hands into a shape, and you can even still move parts of it around or change its features. Once you are done, you take a picture and now you can go show it to your friend without having to bring a block of clay and tools to do it all over again in a different place."
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5ojr1v | Why can my eyeglasses take constant dropping and abuse while my phones screen is so delicate? | Technology | explainlikeimfive | {
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"Glasses are usually made with Polycarbonate lenses while phone screens are made of thin, pre-stressed glass. Polycarbonate will dent and scratch easier than glass because its softer than glass, but as a result it will not shatter. ~~Usually you dont notice these, and if your glasses get really bad, you can actually get the lenses buffed and polished back to a smooth shine.~~ (you cannot buff scratches in the actual lens, as it will alter the prescription, but on the top layer and antiglare coatings can be reapplied.) Gorilla glass on iphone screens, for example, is much harder so that it doesnt scratch and can be made thin enough for the sensors to detect your finger on it. The drawback with this hardness is that instead of deforming (denting) when it gets a hard impact, it will shatter much easier than polycarbonate does. This same phenomenon can actually be seen in diamond \"the hardest substance on earth\" The only way to cut diamond is to use a diamond coated cutting wheel (EDIT because not everyone's 5: or cleave it along an axis specific to its crystalline structure.) . When I was little, I thought \"then how can you cut diamonds to make the wheels to cut the diamonds to make the wheels...\" BUT diamond is SO HARD, it can be pulverized with relative ease. And that pulverized diamond dust is then bonded to cutting wheels to cut larger diamonds.",
"An iPhone 6 weighs about 129 Grams. A Pair of eyeglasses weighs closer to 20 grams. Drop both items from 1 meter high and they will hit the ground going 4.43 m/s For the iPhone that represents 1.18 Joules, while the glasses only register .2 Joules. So, because the phone is heavier, it must absorb about 6x as much energy on impact. URL_0",
"In addition to the other answers like your phone is heavier and your glasses are plastic, a phone has very sensitive technology directly behind the glass. It needs to be able to detect your finger as well as having a 1080p display that is crisp and clear. Because of this, the glass has to be thinner. As with any brittle substance, thin pieces are exponentially easier to break than something slightly thicker. Your glasses also have more give. Meaning if they fall on a lens, the body of the glasses can bend slightly to absorb impact. There is no such give with a phone. Think of the karate move where you break a cinder block. If the to holders are spaced out, its much easier to make it crumble than if you balanced it on one stand and hit it dead center. But seeing how much abuse my glasses take without a scratch, i'm pressed to say that at least mine are plastic lenses.",
"The lenses in your glasses are thicker, and they are curved (which adds impact resistance). They are also probably made of plastic, which is less prone to cracking. And your glasses don't have the added weight of the phone, which adds kinetic energy to the impact.",
"Speak for yourself, every pair of glasses I've ever owned have been horribly scratched the first time I dropped them on pavement. Even if I paid for the 'anti-scratch' coating and shit. They don't shatter though, because they're usually plastic and they weigh a lot less than a phone. Glass lenses are uncommon in eyeglasses because they will have to be a lot thicker than plastic, and therefore weigh more. Plastic phones are nearly impossible to shatter, but they scratch more easily than glass.",
"Your glasses, at least in the US, have to withstand the impact of a 5/8th inch diameter steel ball dropped from 50 inches, as required by the FDA.",
"In my experience repairing both iPhones and androids (9:1 ratio, or more) it has to do, not with the strength of the glass itself, but with the flexibility of the phones. While Apples have prestine engineering under the hood, they have a solid, aluminum case whereas most droids are plastic. When an iPhone hits the ground, it doesn't have any flexibility to distribute the force. I throw my android across the rooms as a demonstration to most of my clients and haven't broken the screen yet. They still stick with Apple and I have several returning customers because of it. Edit 1: Spelling.",
"We must be opposite I've dropped my phone 2368947 times over the 3 years I've had it and it's still in perfect condition I buy a nice pair of sunglasses, drop them once onto carpet and they're horrifically scratched.",
"Mostly relative mass. Your glasses are very light relative to the thickness of the glass, whereas your phone is very heavy. Force against a surface of sufficient hardness and sharpness of profile is what causes scratches (usually sand on the ground, which has particles that are very hard and very sharp), and the more force you generate before the impact the more likely it is to scratch. The simple equation for force of a moving body is F=ma, or force equals mass times acceoeration. Acceleration is usually just gravity in the case of a simple drop, and its constant. So at equal drop height more mass equals more force means more likelihood of a scratch on impact is the simple answer. Where it starts getting more complex is energy transfer at impact, basically does the impacting object bounce off of the other object or transfer energy to it while deforming, and heavier objects are more likely to deform and break themselves instead of bouncing, which also gets into a materials ability to non-permanently deform. It also has to do with internal stresses in the materials. Eyeglasses are usually freely held (so it's fixturing - the frame - is not applying stress to the lens) and there is no internal stress in the glass. Screen glass in phones is held more firmly, so there is more energy transfer between frame and glass, and it's often internally stressed glass, where there is unresolved stress between layers of the profile of the glass, which can make it hold complex shapes easier, makes the surface harder, and has several other beneficial effects, but makes it more susceptible to damage when something like a scratch relieves stress in one area and takes the system out of balance. But as simply as it gets, because a phone is heavier.",
"Chances are you glasses are made with plastic lenses, not glass. They're not as fragile.",
"This is the other way around for me. My glasses don't hold up for shit and I barely drop them. My phone appears to be indestructible. Expensive ass lenses because my eyesight sucks.",
"In the UK, not glasses do not have glass. It's heavy, costs more and is more dangerous. It doesn't scratch as much though. Most spectacles use: CR-39, or allyl diglycol carbonate, is a plastic polymer commonly used in the manufacture of eyeglass lenses. Some people get polycarbonate but it was easier to scratch and with certain solutions, would smeer permanently. Cr39 lenses are cheaper but probably gets more glare so you can have a coating on top that helps.",
"Not a scientist but the weight of the spectacles it's a factor here, they are very light and the frame will help them bounce off most drops.",
"Also with glasses, there's a chance that part of the arms will hit first, which will absorb some of the impact force before the lens hits (or preventing it from hitting at all).",
"Is your phone screen really that delicate? I would imagine the material of your phone's screen is roughly the same durability as your eyeglasses, but your phone's glass is thinner, it's handled more often, your phone is much heavier than your glasses (so when dropped, it lands harder) and it's a flat rectangle with the edges secured which is a very vulnerable shape to breaking upon any sort of impact.",
"I wore glasses for 20+ years, actually broke two lenses. I was a pretty bad case of nearsight, so in the beginning opticians used to advice me to buy glass lenses, as they were much thinner (they were heavy). First time they just dropped from the nightstand and broke as it could happen to a phone, second time I was looking for them and stepped on. Got plastic ones afterwards, still they were much thicker and not at all lighter than glass, they would scratch badly, they were just cheaper. Maybe my last pair was polycarbonated because never broke and were expansive but they scratched a lot and would change color perception like blue-yellow. By my own experience (old) spectacles and phones are fragile and break for the same reasons."
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5olg1m | How do erasers work? | Technology | explainlikeimfive | {
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"Have you ever rubbed your hands together and felt the warmth? That's called friction. When you erase a pencil mark, you are rubbing the rubber eraser against the paper. The friction between the rubber eraser and the paper loosens the graphite particles from the paper. The sticky rubber in the eraser grabs and holds on to the graphite particles (That's why erasers look dirty after you use them) Since the eraser is soft it doesn't rip the paper."
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5omdo1 | why is "night vision" green? | Technology | explainlikeimfive | {
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"Back in the day, night vision goggles relied on vacuum tubes, specifically, photomultipliers, that were much more sensitive to light than human eyes. These tubes basically, as the name suggests, \"multiply\" light, making it easier for us to see. Now, the displays worked like old-school computer screens, or \"tube\" monitors, where an electron beam would light up a \"phosphor\" coating on the screen, making a bit of light that we can see. It just so happens that our eyes are more sensitive to green, and if I recall correctly, green phosphor was easier to produce in a stable form. Basically, we can see green easier, and they kinda worked like old tube monitors.",
"As I understand it, the human eye can distinguish between and see more shades of green than any other color, so having NVGs display in green allows us to \"see\" better. Also why some lights with a map reading mode are green A lot of illumination sources for being all sneaky have red tints because illuminating things in red preserves our low light vision better than any other color.",
"The human eye is the most sensitive in the green part of the spectrum. Because of this, people can identify more shades of green. Night vision technology doesn't pick up color too well, so instead of color you get a grayscale. Gray (or any other color) isn't as easy to see as green, so it's just like black and white only instead it's a greenscale.",
"During the day, the cones in our eyes are their most active and pick up on red light much more effectively than they do green light. During the night, we cross over into our night vision by undergoing a process called dark adaptation. Our rods in our eyes become more active than our cones because their primary function is to pick up on the absence or presence of light (i.e. light or dark). The rods have basically no job during the day other than say the obvious, \"There is light everywhere!\" But, at night, the rods have a much more interesting job to do. The eye's focus on using its rods also makes the cones perceive green as brighter than red since the cones shift their focus and now have the easier job. This is a perceptual reason why night vision goggles and displays use green light. It is also the reason why the vast majority of alarm clocks use red light to avoid disrupting sleep as much as possible."
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5onvaw | if you reverse a reversed video, why does it still look very strange? | Technology | explainlikeimfive | {
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"So you tried to un reverse the backwards running gif? The issue is compression I think. All formats of video have it and it can't be undone completely. So you lose some with the original and you lose some when you reverse it. And you lose some when you reverse it again. It's like putting a phrase both ways through Google translate. Enough is lost that it sounds really weird but still generally the same."
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5onwec | why won't companies like Valve make games such as Half Life 3 which would pretty much guarantee them unimaginable profits? Is there another reason for not doing it apart from the risk of it not being that good? | Technology | explainlikeimfive | {
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"Valve is making money hand over fist with Steam. Half Life 3 has impossible expectations to live up to so I'm sure they'll wait until the risk doesn't outweigh the reward. Why risk messing things up right now when they're doing really well? Square long ago said they would never remake FF7. They're now remaking FF7 because something about their situation changed and they think it's good for business. That might happen in the future to Valve but there is really no way to tell without waiting for it to happen."
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5opx72 | Why do some customer support numbers say "except for Panama"? | Technology | explainlikeimfive | {
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"It seems that Panama has historically had a lot of call centers. I think the issue is that Panamanians are supposed to call a different local number instead of the regular 800 number."
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5oq05p | Why can't an operating system contain kernels from multiple operating systems, allowing programs from either OS to run? | I understand that applications are dependent on frameworks and components provided by the OS in order to run, but isn't the kernel responsible for allowing those frameworks and components to operate in the first place? Couldn't an operating system made from several kernels run the applications from several operating systems? | Technology | explainlikeimfive | {
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"Because kernels expect to have direct access to the hardware. If you attempt to run an OS kernel as a regular program under an OS, first it will fail because the kernel expects to be loaded differently than regular OS programs (usually a kernel is loaded by a small program called a *bootloader* which is written to the first sector of the disk, which is what is loaded by the BIOS). But that's fixable, the kernel is just bytes after all. It's pretty trivial to write a regular program that runs under an OS, puts the bytes of the kernel code into memory, and then executes them. There are some more technical hurdles to get the kernel code actually running [1], but the fundamental problem is that the kernel code will try to directly access some hardware devices. If the OS is running in an environment with hardware protection -- as modern OS's generally do -- it will terminate the kernel process with an error when it attempts to directly access hardware. If the OS doesn't have hardware protection, the guest kernel will succeed in its attempts to access the hardware. But the problem then becomes that the guest kernel and host OS each expect to have exclusive access to the hardware, but in reality they're both sending and receiving commands to the hardware. Lots of incorrect usages of the hardware means that the system will quickly become non-functional. One approach to solve this is to have the host OS mediate access or provide virtual hardware devices to the guest kernel. This is called *virtualization* and is very popular because it saves lots of money -- buying a new physical computer is pretty expensive, but running a new virtual machine in a physical computer you already have is basically free. Three common virtualization products are Xen, VMWare and VirtualBox. Another approach is to re-write the kernel to talk to the operating system instead of trying to access hardware directly. It's no longer exactly a kernel, it's more of a user mode program. This is the approach taken by User Mode Linux, a way of building the Linux kernel to produce a program that can be run under an operating system. [1] One problem specific to PC's is that an x86 processor starts up in *real mode* which is a 16 bit environment. Some ancient operating systems (i.e., DOS) are actually written to run in this environment. But any mainstream PC operating system less than fifteen years old will only have a little bit of real mode code, the sole purpose of which is to set up the processor to switch to *protected mode* which is the 32-bit or 64-bit environment used by the vast majority of the kernel code and user applications."
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5or3ds | How does the black line on debit/credit cards work? | I've taken it for granted for a long time and now I'm curious. | Technology | explainlikeimfive | {
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"It has a magnetic texture that is unique to your account. Machines read it and know which account to access. Extra sentence."
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5or6yo | How can locks/padlocks be mass produced whilst still being unlockable only by their individual key? | Technology | explainlikeimfive | {
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"I'm going to try my best to explain this, but it can get complicated. To understand how this works, you would need to understand how a key cylinder is made and how the key interacts with the cylinder. We'll use a 6-pin cylinder as an example. Starting with the key, as you know there are several grooves along the side of the key. This designates the keyway. Each keyway is usually specific to a manufacturer like Schlage or BEST. When you look at the cylinder on a lock, where you stick your key in, it isn't a straight line, it's a series of jagged shapes that correspond to a keyway. Typically keyways are designated by a letter, for example \"C keyway\". This is done so that a key with the C keyway grooves will not work in a cylinder with an A keyway. The notches on a key correspond to the pins inside the cylinder. There are 6 pins in their own chambers within the cylinder. In each of these chambers there is also a spring so that when you take the key out of the lock, the pins will return to their original position. When the key is inserted into the lock, the grooves push the pins into alignment allowing you to turn the key and unlock the padlock. The pins in each chamber vary in size and are placed in a sequence called the bitting format (I'll touch on this later). The various pin sizes are given a number 0-9, zero being no pin and nine being the largest pin. These pins are placed in a sequence to create a combination. Keys are cut to these different combinations so that one key doesn't operate every lock. Now, remember that bitting format? The bitting format is a sequence that allows us to come up with 4096 possible combinations. How did I come up with that number? Using the 0-9 size pins I mentioned earlier, you would put a different sized pin in each chamber. For Example: 965857 965859 965851 965853 Each of the 4 combinations above have to be operated by a different key (assuming there is no cross keying or master keying, but that's another time). When coming up with these combinations, it's important to note that no 2 numbers in the sequence can be the same when they are next to one another, which is why I left out 965855. Since this is the case, there are only 4 possibilities per sequence group. Since there are 4 possibilities per group and 6 pins, 4^6 is 4096 possible combinations. Out of those 4096 there also arises the issue of ghost keys, which are keys that are so close to another combination that it's possible for them to accidentally unlock another cylinder. This is why your friend's key will sometimes work in your lock. Typically there is keying software that eliminates these groups before the bitting list is finalized, but when things like padlocks are mass produced, they reuse the same bitting format because of the limited number of combinations. So to bring this all back around, because of the different pin combinations in a cylinder, there are around 4096 possible combinations (minus ghost keys) that can be used when mass producing padlocks. They are all operated by a different key that is specific to the padlock's keyway. I realize this is too much information and there were some points I didn't touch on...but it's fun to explain.",
"The lock has a set of pins of various sizes that when lined up correctly allow the lock to turn. Depending on the lock, there's usually about 4-6 pins. For a 5 pin lock, let's say there are 15* different pin sizes that can be put in any permutation. The number of permutations P(15,5) gives 360,360 unique locks. During manufacturing they just rotate through different pin sizes either at random or according to a process which ensures that no two identical locks end up in the same lot. \\* 15 comes from looking up the number of sizes in a Schlage pin replacement kit. Some pin replacement kits have up to 28 sizes which would result in 11,793,600 unique pin sets for a 5 pin lock, or 271,252,800 for a 6 pin lock.",
"They aren't unlockable by an individual key. It's rare but your house key can open up othe houses as well. The amount of houses you'd have to try before it would work would be an amount that you'd probably be arrested before you succeeded.",
"Most people don't realize that not ALL locks and keys are unique. Even autos have keys which duplicate those of other similar brands. It's just it's so rare that a key to one car will start another, it's not often seen. But it does occur. Same is true for house keys. If people REALLY knew how easy it was to pick a lock, they'd think twice about buying cheap locks....",
"This past year I purchased a house and decided to purchase all new locks around the house. Went to my local hardware store purchased about $100 worth of door handles to find out they all worked with my old house keys after I installed them all. Couldn't believe it.",
"While there are some good answers here, the dirty little secret is manufacturers and consumers (industrial or otherwise) are kinda lazy, and many things are simply keyed alike: [From The Eleventh HOPE: \"This Key Is My Key, This Key Is Your Key\" by Howard Payne & Deviant Ollam]( URL_0 )",
"There is a limit to the number of possible keys for any given lock series. Any given lock has a number of spring loaded pins that can have a small number of positions, the cut of the key moves the pins up and down to align break points with the edge of the lock cylinder so that the lock can turn. A cheap lock might have 4 pins and each pin has 5 possible heights that it can be cut to. Such a lock would have 5^4 possible combinations, which would be about 500 different keys. a more well made lock might have six pins capable of 10 positions, and that would give you 10^6 possible combinations, or 1,000,000 different keys (that said, a lot of combinations near all high or all low would tend to be avoided- you wouldn't want to be able to open the lock with what was essentially a key blank) high security locks may have additional features like angled teeth that rotate the pins to a necessary position, which adds another dimension for potential unique keys, as well as making picking the lock much more difficult. --edit-- that should be 4^5 on the cheap lock, for 1024 combination, and thanks to the kind soul who pointed out my mistake to me."
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5orknu | My Mum hates it if I spend a few hours gaming, yet if I watch TV for the same amount of time, so doesn't mind. Myis this; how is gaming worse for you than watching TV? | Technology | explainlikeimfive | {
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"Honestly, it is not worse for you. But people unfamiliar with gaming probably think it's weird and don't understand what you are doing. And the fact that it's so immersive -- like you don't want to be interrupted or talk with your Mum during the game -- may annoy her."
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5orrvu | Tesla released all its patent on their car in 2014 so that anyone can use them. Why isn't there any other Car Co. using them ATM? | Technology | explainlikeimfive | {
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"There is no way to know they aren't. There are a lot of patents and licensing that you would have no way to check on who is using what and How. Also using a Patent doesn't mean it will look like Tesla, that is a different thing.",
"Any number of manufacturers easily could be using various parts and concepts invented under a Tesla patent and you'd never know it. As far as you know the latest Ford Hybrid is using the battery charging systems of a Tesla, and Ford-Original everything else. Nobody's told you because the particular design of the alternator isn't exactly flashy in a banner ad or sales pitch. Nor is admitting that another company does something better than you. If you're wondering why nobody has taken ALL the Tesla patents and made a clone, that's just business. Tesla is already having trouble finding markets for their vehicles. Even if you skip the most of the engineering, as a new manufacturer you'd have to still pass all the regulations and safety standards and figure out exactly how to buy/make the exact parts required for the whole car. THEN you could START marketing your new car, and MAYBE find some buyers. This represents billions of investment to make a vehicle that would now be 5-10 years out of date (depending on how long it took you to solve the startup problems), and still have a tough time selling against a cheaper, newer, and arguably better standard transmission vehicle. And consumers expect you to repeat the entire operation within a calendar year to produce the 2020 Edison (that they still won't buy)."
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5orzei | If text messages are encrypted, how can government agencies access them? | Technology | explainlikeimfive | {
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"The communication between your cell phone and the cell tower is encrypted, but it is not end-to-end encrypted between your cell phone and the other cell phone. That means that there are three people that can read the message: you, the person who controls the cell tower, and the person you're sending the message to. If the government controls the cell tower (by using a cell site simulator, commonly referred to by the brand name \"Stingray\"), or compels the telecom company that owns the tower to give them the messages, they can read them.",
"Encryption is between a sender and a number of recipients. Typically, as in this case, you are the sender and your service provider is the recipient - NOT your friend's phone. That is the nature of your relationship between you and your provider. So the recipient, your provider, has *plaintext* access to your message and delivers it on your behalf to a 3rd party, your friend, via his phone. The encryption scheme is only meant to keep unauthorized 3rd parties out. For example, anyone with the equipment can listen in to the radio signals from your phone, but they're not the intended recipient, so your message is guarded against them. Likewise, the internet is composed of networks, and your message may have to traverse a network your carrier doesn't own to get to its destination. Your carrier encrypts between itself and it's destination across that 3rd party network so all they see is the *cyphertext*. But never forget you're talking to your carrier, not your friend; you don't own the radio frequencies, or the right to broadcast on those frequencies, and you don't own the network your provider carries your message on your behalf, they do. They have unencrypted access to the communications you establish with them. There are applications that encrypt messages between you and your destination directly, but you need to be able to build and install ALL the software yourself, from the OS up, because these phones are untrustworthy closed platforms that may and historically have and probably still do contain backdoors, all the way down to the hardware level. So in conclusion, cellphones and proprietary platforms and software are inherently insecure and untrustworthy."
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5osa98 | Why is there a seemingly larger risk of getting viruses on a laptop/desktop than there is while accessing the internet through a smartphone/console? | Technology | explainlikeimfive | {
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"Consoles and some mobile operating systems (iOS) are \"sandboxed\". This means that only authorised code can run, for example in iOS you can only run apps signed by Apple from the App Store; unless you jailbreak it. Consoles are the same. On normal computer you can do whatever you want, which allows bad stuff in.",
"With great power comes great responsibility. A home computer is pretty much anything goes, which is great for people who needs lots of options. A smartphone or console is much more limited in what it can do, so it's harder (but not impossible) for bad software to get in.",
"The existing comments are all great ideas. I would add this: Think of what you might target as a producer of malware, whether that's ransomware or otherwise. Going after end users is not going to be profitable. End users don't often have the cash to shell out to ransom their files. So malware producers target businesses that can shell out large sums of cash as ransom (either because they have no backups, have bad backups, or it's cheaper to ransom the files and restore than to recover the backups). With certain industries there may be trade secrets to steal and sell, or perhaps a state-sponsored malware attack on the strategic utility or industry. And what do you know, those bigger players all run Windows. Even if they use Linux servers, workstations are the way to get at the file servers easily and efficiently. And users are still the #1 attack vector.",
"All the comments here are absolutely correct. There are a ton of reasons why laptop/desktops see more viruses than smartphones and consoles. I would say the top two reasons said by u/Gnomio1 and u/ckindley argue that creaters of malware are going to focus there energy on what gives the greatest return. On top of that it comes down to the type of data. PCs (even most enterprise servers/storage) run block or file data. Mobile devices (excluding consoles here) tend to access data through object storage. TL;DR basically means PCs are predictable and the ways we access than is well known. Mobile devices are still new. It takes someone who keeps up with modern programming languages to attack. So at the end of the day there are fewer people who know how to attack mobile devices and it's more cost effective to go after PCs. Combine the two and there's your answer."
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5osj3g | What would a videogame look like if you could see the world as it was loading? | Technology | explainlikeimfive | {
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"Depends how it's drawn. Like when you draw a picture do you draw it in pencil and then paint it? Or do you draw a little bit and paint it and then draw a little bit more. I believe it was wolfenstein which was the first game to render maps in low quality and then quickly re render in higher quality as the user would look at certain sections (to appear higher quality in areas of interest to reduce computational load)",
"Every game is different so this is going to have as many answers as there are game engines... For the most part though, it's going to look like crap."
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5otmu1 | Do cell phone companies limit/throttle data because there actually is a bandwidth shortage, or is it a cash grab? | Technology | explainlikeimfive | {
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"The incentive to throttle bandwidth is 1) Generally to ensure everyone using the network has a decent speed 2) To try to limit the growth of data usage. There is only so much data that can be passed through a antenna/radio. The limits are simply physics. Typically, the higher the frequency, the more data per unit time can be transferred. The downside being higher frequencies do not travel as far, nor do they penetrate buildings nearly as well. As more and more people use data more and more intensively, there comes a point when no one can use anything effectively. If you have ever shared wifi, you know what happens. Someone is watching a HD stream, meanwhile, the total available remaining bandwidth is reduced. The two most common solutions are adding more frequencies used (ie adding more data channel). This is very expensive as new antennae must be installed, new radios added (very expensive on their own), etc. And each frequency has its own quirks. The second option is adding more towers to a network. Which is far more expensive then adding equipment. As well, while the cost of data falls every week for cellular providers, they must balance extracting every last dollar they can from their customers against providing effective service to those same customers. If your provider gave truest unlimited data, even for a high price, very soon everyone would start using more data. Eventually this causes everyone on a tower to have download speed issues, as there simply is no room left within the spectrum for data transmission. This is why cell company's deploy temporary cell sites at large festivals. Otherwise there network gets slammed, no one can send a text, let alone place a call and everyone gets angry at their phones. The cell companies are currently undergoing a massive upgrade. Several (several!!!) new frequencies are being added. Source: I work in the industry. Also, if you are not afraid of working at heights, willing to work away from home (a lot), you should consider a career change. The industry is booming and a lot of places are having manpower shortages. Plus the pay is good. God bless overtime. Source: Overworked guy dealing with industry wide labor shortages."
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5otupv | Why are bulletproof vests not reusable? | Technology | explainlikeimfive | {
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"The easiest way I can explain this, is a kevlar vest is like a cube of jello? If you smack the jello and crush it, it will break apart, but absorb the shock, if you hit it again it's just a pile of mush so it will barely stop your hand, your hand being the bullet.",
"Because the vest can stop a bullet only if certain parts of it are at full strength. When a bullet goes though it the layers will weaken as they stop a bullet. In fact some of the layers are designed to breakdown as they get struck by the bullet. As they those layers degrade they absorb a lot of the force of that bullet. But if I have a new vest and a vest that has been shot a few times, the used vest will give much more unreliable protection. They new vest will be far more reliable.",
"They are not bulletproof, they are bullet resistant, that resistance goes down each time they are struck and eventually they will fail and bullets will pass through them."
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5owj4l | What would happen if everyone on a plane didn't switch their phone to flight mode | Technology | explainlikeimfive | {
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"Most likely? Nothing. The flight would proceed as normally, with no real notable incident. But potentially? If the chance of catastrophic failure is increased by .1% ... is that really worth not switching your phone to airplane mode? It's not like you'll have service at 30,000 feet, and to be honest... why gamble?"
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5owl29 | Why is the Python language so heavily divided between two versions (2 and 3)? | Technology | explainlikeimfive | {
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"Python was already really popular when version 3 came out. Version 3 had a lot of non-backward-compatible changes which broke most version 2 code. A lot of Python projects aren't just one guy's Python code, they combine lots of people's Python projects together. If you maintain a Python 2 project, you can't move that project to Python 3 until you do some work re-writing your own code, *and* the maintainers of all the projects your project depends on also do similar work re-writing their own code. Much Python code is written and maintained by volunteers, or written and maintained by people working for companies in the course of their jobs. The thing is in the first case, as /u/gr33n3r2 points out, the work is tedious, time-consuming and un-glamorous. Most volunteers are more excited by, and thus more likely to spend time working on, writing new code and adding new features to existing code. For people who publish code as part of their job, often the code's a by-product of writing some product like maybe a website. The thing is it's easy to justify to your boss writing some software that doesn't exist and needs to exist in order to build the website your company wants to create. And it's not that hard to convince the higher-ups to let you put it out there so other people can use it, it's not a competitive advantage because it's so far removed from the things that actually make your company money, it adds to your company's reputation among technically savvy people who recognize good computer code when they see it so it's effectively a recruiting tool for your IT department, maybe some of those open source volunteers will contribute features or bugfixes to the public code that improve your website without costing you a dime, maybe allowing you to publish it under your own name and enhance your own reputation is critical to your employee morale and makes you less likely to demand a raise or leave the company, etc. When the website already exists and runs perfectly in Python 2, it's not so easy to justify to your boss that you should spend time re-writing the software that already exists and runs perfectly just so other people who use it can use Python 3, which your company doesn't use."
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5ox11k | Why are fire animations, fogs and shadows in video games so demanding for graphic cards? | Technology | explainlikeimfive | {
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"Imagine your graphics card is a famed renaissance painter named Giancarlo Pasquali Uberti sitting in a room. In this room is a canvas, paint, and a pneumatic messaging tube like they have at bank drive-thrus. Giancarlo also has a brother named Cirino Pasquali Uberti that he works with. Cirino can't paint, but he's great with customers and runs their shop. Cirino's job is to take orders for paintings, then send messages to Giancarlo that tell him what to paint. He can't fit big messages in the tube, though, it's real small, so each message tells Giancarlo how to paint a single object. A message might be like \"Paint an apple 50cm from the left edge of the canvas, 20cm from the top\". Giancarlo is very fast, but it takes him longer to finish a painting if he has to paint lots of individual things (it wastes time writing a message, sending the message through the tube, opening it up, reading it), or if he has to paint a really big canvas. & nbsp; Now, Cirino and Giancarlo are pretty smart, and they've figured out some tricks to make paintings go faster. Cirino takes great notes while talking to customers, and knows how far away each object in the painting is supposed to be. This is known as its depth. While Cirino isn't a good painter, he's very organized, so he sorts the messages by depth, closest object to furthest, and throws away any objects that are hidden behind something else. The only messages he sends to Giancarlo are just those objects that will be seen in the painting. This is way faster! Giancaralo knows that it's in order, so he doesn't have to waste time painting things that overlap. Since it takes time to paint an area of the canvas (the bigger the area, the more time), this is very efficient. Giancarlo doesn't have to paint over the same spots on the canvas at all, he just paints every spot once. & nbsp; Then comes a job to paint a still life with a frosted glass vase in it. Cirino sorts everything, and realizes there's a problem. The glass vase is translucent, you can see through it, so it changes how stuff behind it looks since it isn't totally clear. No amount of sorting can fix this, and he eventually realizes that Giancarlo is going to have to paint over the same spot twice to get the right look (remember, he can only tell Giancarlo to paint one object at a time in his messages). The clever brothers think about this for a while, and come up with an idea. & nbsp; Their new plan is to work on the same painting twice. First, they do what they usually do, sort all the solid objects front-to-back, and only paint the ones that can be seen. Second, they sort all the see-through objects back-to-front and Giancarlo paints each one in order, still careful not to paint any that would be hidden behind a solid object. Sorting the see-through objects back-to-front makes sure they look right if two see-through objects overlap, like if you're looking at that frosted vase through a stained glass window. It wouldn't look right if they painted the vase in front of the window! The results look great, but it's a lot more work than just painting solid objects. & nbsp; Now, for just a single vase it's not so bad, but once you have a scene with lots of smoke, fog, shadows, etc, Giancarlo spends a lot of time going over and over and over spots he's already painted to build up these translucent layers. This slows things down, and it's a big reason why your GPU struggles with these sorts of effects.",
"It's really hard to ELI5 graphics algorithms, but I'll do my best to keep it simple. **TL;DR:** All those effects make the GPU do a bunch of work twice (or more) instead of once. Of the three special effects you list (fire, fog, and shadows), two of them are actually the same thing as far as a GPU is concerned: fire and fog are both examples of partially transparent objects, so I will group them together. The work a graphics card has to do to draw a scene can be broken roughly into two parts. The first part is the work it has to do for each 3D polygon (triangle) in the scene to determine which pixels that triangle covers. The second part is the work it has to do for each pixel to calculate the color and brightness of that pixel. **Transparent objects are demanding because they make the GPU process each pixel multiple times, multiplying the amount of work done in the per-pixel phase of rendering.** **Shadows are demanding because they make the GPU process each triangle multiple times, multiplying the amount of work done in the per-triangle phase of rendering.** Without transparent objects, there is exactly one surface visible at each point on the screen (disregarding anti-aliasing). Therefore the GPU only has to calculate light and color for each pixel once. With transparent objects like fire and fog you can see multiple layers at each point on the screen, so the GPU has to calculate light and color for each layer at each pixel, then blend them together. To draw shadows, the GPU has to draw the scene from the perspective of each light that casts shadows, just as if that light were actually another camera. It usually doesn't have to calculate any color from the light's perspective, but it still has to go through the process of drawing each triangle in the scene for every light. It turns out that many \"demanding\" effects in video games are slow because they multiply some part of the work of drawing a scene: Transparency: Multiplies per-pixel work in the areas covered by transparent things. Shadow Mapping: Multiplies per-triangle work (plus some extra work at each pixel). Anti-Aliasing: Multiplies per-pixel work at the edges of each triangle on screen. Global Illumination: Multiplies everything by everything else until your GPU catches on fire... If that all sounds confusing, that's because it is. I can try to clarify if anything about my wall of text is particularly unclear. Edit: I should mention that the problem of drawing pixels multiple times is called \"overdraw.\" Edit2: I should also mention that \"duplicate\" work was probably a poor choice of words. It's not redundant, it just has to process the same point multiple times instead of just once.",
"**TL;DR**: Accurately simulating any 3D scene is impossible in a computer game. About 10^19 photons hit every square metre of earth during a single 1/60th of a second frame, so obviously simulating even a tiny fraction of the photons in a normal video game scene is just intractable. But a lot of simple stuff can be simulated in a way that looks good enough without doing it accurately. Fire, fog, shadows, refractive glass, mirrors and all kinds of other effects are stuff that *don't* work in this simple way of rendering things, so require a more complicated simulation to make them look any good. More complicated means more work for your graphics card. So the question might rather be: *why are things like rendering a chair in a room with two small lamps and no windows easy for graphics cards?* Below I will try to answer both questions. **More info:** Traditional 3D rendering works backwards: you start at the virtual camera and, for each pixel you want to render, trace out a line until you hit an object - each line goes out at a slightly different angle for each pixel. You then look at the angle and distance from that object to every single light source in your scene and calculate how much light the object is receiving. Then, examine the material the artist gave that object and see how it reacts to light to determine what colour it is at that spot. You then draw that pixel that colour. (This is backwards because in reality, obviously, light travels *into* the camera, not out of it.) This requires you to trace lines to see what they hit exactly the same number of times as there are pixels in your image. For each pixel you also have to calculate distances and angles to exactly the number of lights in your scene, though games tend to use tricks to reduce this number (by making lights outside a certain distance not count, or by pre-calculating a lot of this information so some more can be skipped.) This is all quite doable and is represented in [this diagram]( URL_1 ). Now none of this allows you to render shadows: suppose you're calculating a certain pixel and calculating the distance and angle from the object in front of that pixel to the single light illuminating the scene. At no point do you check whether there's anything in the way which would prevent light from getting to that point. To do that you'd have to not just calculate the distance and angle, but trace another line to every light (the shadow ray in the diagram above) - that takes more calculations and makes it slower. Again there are tricks: you could say that only stationary objects and light sources can cast shadows, pre-calculate all that information and then you don't need to do it every frame in the game. But this of course doesn't look as good. Basically for the other things the answer comes down to the same thing: forcing the engine to trace more lines. Sometimes you're forced to trace lines from the light sources instead of from the camera - this is very wasteful as you have no idea which will end up hitting the camera (perhaps after bouncing off some objects); any that don't have no effect on the scene at all. You're forced to trace far too few to actually look good and hope you can smooth out the resulting mess to look decent. Other times, like with reflective surfaces, you have to trace the bounces off the objects. If you have two mirrors facing each other, you have to cut off the trace at some point, which will prevent the render taking an infinite length of time but result in a black spot in the mirror. How about fog? Basic fog is actually easy and used to be a way to make games run *faster* - when you worked out what colour a pixel should be by tracing out a line to the object in front of it, you'd also mix that colour with the fog colour according to how far the object is away from the viewer. Then at some far-away distance, all objects would be exactly the same colour, and you wouldn't have to do any further calculations. It could sometimes produce [weird effects]( URL_0 ) if the fog doesn't match up with the rest of the background. But real fog isn't like this - as light passes through it, it scatters, making things in fog look blurry. It's partially transparent, meaning you can see things on the other side, but also the fog at the same time. So suppose you run the above algorithm for fog: you trace out a line for a single pixel and discover the first thing it hits is a region of fog. You can't just colour that pixel according to the properties of fog, because then the fog would be opaque, so you have to first do the calculations for what is illuminating that little area of fog, and then continue calculating. A naïve approach would be to continue the line through the fog until it hits an opaque object, and mix the colour of the opaque object with the colour of the fog according to the distance of the line segment that passed through the fog, [like this]( URL_3 ). Already this is more complicated, but this is not a perfect simulation. As I said, fog scatters light: each photon that passes through can be randomly disturbed so that it goes off at another angle. Also, the single line you trace through the fog might pass through a region which is shadowed - [like in this photograph]( URL_2 ) and those patches should be darker than if you just treated every path through the fog of the same length the same. So what you really need to do is calculate the illumination at every single point through the fog, randomly make the line you're tracing bounce off somewhere else. Except you can't do it randomly because then each frame, and for each adjacent pixel, the angle would be different - you'd get a flickering mess of noise. Instead you want to simulate the fact that each pixel is the aggregate of billions of rays of light, and simulate that they're all bouncing at once! Of course, it's not possible to trace billions of lines for each pixel that hits fog, nor to calculate illumination at every point within it, so games use tricks, but to get the look correct, you still need to do a lot of extra calculation. If I may digress a little, the problem is that you can't treat things like fog as being *homogeneous.* For 3D that means you can't treat light going through it as having only two interactions: one at the beginning and one at the end. (In fact it would be better to just have one interaction!) The traditional approach to cheaply modelling transparent objects is to pretend that a ray of light passes into, say, a glass paperweight, changes angle once due to refraction, passes through the paperweight being continuously attenuated as it does so, exits out the other side and is refracted again. The ray of light does not change path inside the glass, it never encounters a bubble, trapped piece of dust or anything else. If you want to simulate this things that occur in a *heterogenous* transparent object, where interesting things may happen inside, you have to chop the object up into thousands of pieces small enough that you can't see them, and perform complex calculations as your ray of light passes through each tiny volume. This is a general problem in simulation: whenever you can't deal with something as being defined by a simple process inside it, a start and an end, things get hard. **Digression over:** Fire is like glowing fog, so it has a lot of the same problems, but it also represents something very hard: a light source with size. When you calculate the illumination of an object, it's much easier if you can pretend all the light from each source is coming from a single infinitely small point, rather than being spread over, say, the element of a lightbulb, or a fluorescent tube, or a whole fire. This is because to accurately simulate the illumination you'd need to act as if there were millions of tiny lights all over the surface of the object, and calculate how far and at what angle they were to the thing being lit up. Millions of lights means millions of calculations - which again is not possible, and again the tricks that can be used to fake it are still computationally expensive. But also if you want to simulate the way fire moves rather than just recording a video of it, that is a very difficult process. Again you are reduced to trying to simulate the fire as lots of tiny particles - but nowhere near as many particles as makes up a real fire. So you try to apply physical laws to the particles but they can't actually behave physically because they're too big or because information like the air currents in the environment is lacking. Usually people just use a recording with some tricks to make it look less like a recording.",
"A lot depends on how all these elements are handled in a game. Best case scenario: - The fire is a simple object, animated in a 3d program and let loose in the game. The animation loops and it's quite noticable but you can get away with it. - The fog is just things in the distance getting blurrier. Looks quite bad but it's cheap. - Only static (non-moving) objects cast shadows, no dynamic lights. This might sound like a lot of assumptions but it's not entirely unrealistic and there certainly are games which can use this simple model. It's very, very cheap. Worst case: - Fire is made using multiple particle systems including multiple types of flame, randomized smoke, lights, dust and small elements flying around wildly. - The fog is also a large particle system with added blur effects - Multiple lights with multiple dynamic objects casting dynamic shadows This model is used in games with better graphics and there are multiple performance concerns. I won't go into the details but the main issue is that many of the effects require multiple passes which basically means the image you finally get on the screen needs to be drawn multiple times by the GPU. First object geometry, then lighting, then shadows, then particles, then special effects like antialiasing, bloom, ambient occlusion etc. and if you have a lot of those they can easily become a GPU bottleneck. Source: Make games. Tried to be ELI5 I know this is an oversimplification.",
"The shortest and simplest ELI5 I think is that, as in real life: - Fire generates light. - Fog blocks and alters light. - Shadows are cast by light from different sources. All these things either generate or alter light and dynamic light calculations are complex and grow exponentially with the amount of light sources and alteration sources present. the addition of 1 light source does not just add one light source or one more shadow to a scene, an additional light source interacts with the other light sources and every new light source or alteration in the available light alters the effects of every other light source or alteration in the available light. A really simplistic analogy on the scope of adding just one light source or alteration to light is this: Imagine counting to 9. You can do that in 9 counts and it'll take you under 10 seconds. Now add 1 more digit. Now you have to count to 99, which takes a lot longer, around 1 and a half minute. Now add another digit. Now you have to count to 999, which will take you around 17 minutes. Now another one. Now you have to count to 9999, which will take you over 2 and a half hours. And so on. Similar complexity exists in calculating the effects of light sources in 3D. In 3D Processing there are a ton of shortcuts and tricks to limit how large an impact a single light source has, but the effect will still be great with every one you add.",
"Just logic here but shit man compared to just still images there's alot going on image wise in fire and fog. It's more complicated so therefore it's harder to make",
"Short explanation. Turbulence is hard to model. That's why we can only predict weather a few days out. Fire and other \"random\" patterns take a lot of computation to look realistic",
"I feel like a lot of the answers on here are missing the \"like I'm 5\" part. As far as the animation of fog and fire they are represented by particles. Each particle makes a shape based on some behind the scenes math, but only one particle doesn't make for a convincing fire or fog. So the game has to create many particles with even more complex behind the scenes math to tell the particles which way to go, how long to live, the size and shape at birth and death, if it's colliding with other objects, how it can spread or if it can spread, is it making light or is it interacting with other light sources... So the computer has to keep track of all of that information for each one of the particles. The more realistic the fog or fire, the more particles, the more the computer has to keep track of. This leads to the shadows. One shadow is pretty easy. There is one source that sends light in a direction from it. When that light interacts with, say a character, it has to take in all of the shapes it hits on the character. The light draws a gradient from light to dark on each of the shapes it hits and then it also draws cast shadows. Those cast shadows on everything on the other side from the source. (source) < < Light < < {character} ~~cast shadow~~ [ground] Now that's relatively straight forward and doesn't take much power from the computer. That's why in a lot of fast paced games there is one global light that casts a fairly simple shadow under the characters. But, when you start adding more light sources in more cinematic games, with more objects interacting with it, with fog interacting with it, and fire with light making particles it compounds how much math the computer has to figure out to make everything look correct. Hope this was ELI5 enough. Sauce: Am animation director.",
"When the camera is looking at a solid object the computer only needs to calculate the color based on the most basic info- desired texture, ambient light, angle, etc. When the camera is looking at a translucent or transparent object (such as fire and fog) it needs to calculate this information for both the object you are looking through and the object behind it, as well as calculating how looking through one effects the other (opacity, refraction index, etc. ) each layer making it more complicated. Reflections have this effect too, as the computer effectively sends a line from the camera, calculates the effects of the object it hits (reflection, finish, color, opacity, angle of reflection) and adds to it the information for the object it lands on (when I was learning 3D modeling this was called Ray-Tracing). Again, the more objects the GPU has to consider, the more information it has to calculate, the slower it goes. Shadows use the ray-trace effect as well but the rays come from the light source and trace around objects.",
"It is about the number of things you see. The smog itself PLUS the things behind it. The shadow itself PLUS the ground, that is a mix between draw the ground, determine the direction of the shadow and the ground shadowing itself. Edit: this is a reason for Minecraft to be so heavy processing, lots of blocks and dropped items are visible at the same time, and each one has its own set of proprierties ready to be triggered. Walk by will make them emit walk noises, break them will take specific times. Er... oh, I think I lost myself a bit.",
"Everything a graphics card renders is a geometric shape. Each geometric shape, no matter how big or small, takes basically the same amount of power to render. The less like a geometric shape the thing is you're trying to render is, the more shapes you'll need to combine to make it. Organic-looking objects are the least geometric things. On top of that, if the items are not 100% solid, you'll need to render items behind it as well. Now let's say that the object generates its own light (like fire) or modifies the existing light as it passes through (like fog) and you're complicating things even more.",
"Fire and certain types of fog require transparency. In order to draw something that is transparent you need to draw the pixels behind it first. In order to make fire and fog look realistic you need to use multiple images which means the GPU has to redraw the same pixel multiple times. This is called overdraw."
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5ox83l | Why do radios stations from far away come on when it rains? | Technology | explainlikeimfive | {
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"Radio waves are just another form of light, and like visible light, they can be reflected off objects. The phenomenon you're talking about probably has to do with [Tropospheric Ducting]( URL_0 ). During a rain storm, you might have a layer of cold air near ground level bordered by warmer air higher up in the troposphere. This is called a temperature inversion (since normally the reverse is true). This creates a \"duct\" of cool air near ground level. The boundary between the sudden rise in temperature has a high refractive index. The denser cooler air slows the wave a little more than the warmer air, making it curve downwards. When a radio wave enters the boundary between cold and warm, it reflects it back down to Earth. If it hits this boundary at a low angle, it can curve well beyond the horizon. So it's not really the rain that's causing it, but usually the front that brings in the storm. Rain can actually have the opposite effect at higher microwave frequencies. Scattering the signal until its unintelligible."
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5oxhtm | Is it legal to pirate a game I own legitimately? | Technology | explainlikeimfive | {
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"If I remember correctly, you're not buying the game per se, but a license to play that game on whichever system you buy it for, which makes playing same game technically illegal on an emulator. Hopefully someone else can verify/expand on this.",
"I'm assuming you're in the US. There are two things that govern the law on this issue: US law and the agreement you have with the software publisher. First, let's talk about US law. US copyright law generally assumes you bought a copy of the program. As the owner you can keep and use the program or you can sell the program. If you keep the program, you can make an archival backup of it, but that's it. If you sell the program you have to destroy the backup. Emulators aren't necessarily illegal under copyright law. You can't copy the code directly from a system, but if someone makes their own system to play the games then that's fine. I don't actually know how most emulators are made, so I couldn't say if they're legal or not. Given all of that, you should be able to play your game on an emulator since you paid to run the program and you can run the program on whatever system you like. I also don't know if you can say that the disc the game is on is your \"backup\" and the ISO you use on the emulator is your main copy - there hasn't been a court case on that as far as I know. So that's all and good for US law, but most software publishers also include an End User License Agreement (EULA) with additional restrictions. They typically say that you are actually buying a \"license\" to play the game, so you can't resell it or back it up or anything like that. US courts have been split on whether EULAs that force you to buy a \"license\" instead of outright buying a copy of the program are effective. Some circuits have said yes, others have said no. tl;dr US Courts are split on how much they will enforce an EULA. If an EULA is completely enforceable, it would be illegal for your to pirate your own game. If the EULA is not enforceable, it's legal for you to make a backup copy of your game. Whether you can play your backup copy on another system is a legal gray area.",
"No, that's not legal. Owning a legitimate copy doesn't give you the right to download a copy from an illegitimate source. However, you are allowed to make a backup of your own copy. So it's legal to rip your own iso from your own discs.",
"Generally, no. The terms of service you agreed to when you purchased the game only allow you to use the game in the medium that you purchased it on - you are not allowed to utilize it on other platforms.",
"its a gray area but generally speaking it wouldnt make sense to prosecute unless you were distributing copies as that is what takes away from sales. The fact that sony discontinued the earlier playstations is not fair to you as a consumer of their games and I think theyd agree with you as a company as the cost of producing those consoles to too high compared to the value theyd provide. if you bought the games thats as good as you can do"
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5oxjlr | How do people get roms off of cartridges? | When it comes to, say, ripping a rom off of a gba or nes game, what is the method for that? I'm asking because I'm genuinely curious, not because I'm trying to :P | Technology | explainlikeimfive | {
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"You just need a device that can connect to the cartridge and to a computer, at which point the cartridge either appears as a serial device. [This]( URL_0 ) page shows various projects that have been done with gameboy cartridges."
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5oxlhm | How the Dark Web operates | Not looking to know how to get on it, just how it actually operates. How it stays hidden, etc. | Technology | explainlikeimfive | {
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"It operates just like the rest of the Internet. It's computers that use IP messages to send information to each other. It's just not indexed by Google or send to your browser as HTTP messages. For example, the email network is dark. My email server sends SMTP messages to your email server. Both machines have a database of the messages they've received, and they don't let Google see it or anybody see it. There might be a webmail server that you can log into and see the contents of the mail server's database, but you're not seeing the actual mail server."
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5oxs2o | White Hats of Reddit, what are simple steps everyone should be taking to preserve anonymity and security online? | Technology | explainlikeimfive | {
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"1. Buy a brand new laptop with cash. If you are ultra paranoid have somebody else buy it for you. 2. Tape over or otherwise disable the webcam. 3. Never log into any personal website with this laptop. Never log into facebook, email, reddit ect. 4. Never have the battery installed in the laptop when not using. 5. Never have the laptop plugged in while your home modem/router is plugged on at the same time. 6. Always use open networks to access the internet. 7. If there are no open networks at home and you want to use the laptop at home get a burner cell phone that you can tether to for data that you also pay cash with. Pay cash for refill cards.",
"This may sound silly, but don't use Facespace etc and post information about yourself. One of the easiest parts of data mining is grabbing everything people already willfully share about themselves.",
"I'm not a white hat, just interested in this particular topic lately. I mainly use [ URL_2 ]( URL_2 ), along with [/r/privacytoolsIO/]( URL_1 ). But there's also [this]( URL_3 ) guide from [Electronic Frontier Foundation]( URL_0 )."
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5oxt8t | What does the chip on our cards do, why do we only now need it, and why can't every store/vendor mainstream the darn thing so we don't have to swipe? | Technology | explainlikeimfive | {
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"It changes your card number every time it's used, and it prevents itself from being swiped in a reader activated for chip. This lowers the likelihood of your info being stolen and used by magnitudes. Now, most stores in the US have a reader capable of accepting chip. However, both their bank and their card processor has to allow it and the reader needs to be updated to allow it. Also, readers need a certificate (which says that they are genuine and safe), which can take months to acquire even if you everything else setup. Also, the UK and most if the world has had them for years. Also, in the US we had tap cards like a decade ago, but scary news stories caused people to fear the tech. The one big chink in the armor is online payments, as you have to enter the physical numbers. This is where \"Pay with Apple Pay\" come in. Services like PayPal and some banks (Chase I believe) also allow online payments, but I don't think they are as secure, as your bank account number is being used to authenticate the purchase, but I could be wrong and they actually use tokenization."
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5oya18 | What's the hold up with the ability for residents to text 911 for emergencies? Is it a technology-related problem? Jurisdictional? | Technology | explainlikeimfive | {
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"There is a technological hurdle and then the organizations willingness to upgrade their systems. Legacy 911 call routing applications only handle voice as that was all that was required or envisioned at the time. Voice is a lot easier to hand off to PSAP (public safety access points) than text is. Most text based applications for 911 require persistent connections during a texting session because you wouldn't want the first text to go to operator 1 who responds, but the second text goes to operator 2 who has no awareness or has to read the original lines to get up to speed. This requires some modern network features, software applications, and upgraded hardware usually. Due to these reasons not only does the 911 carrier (Verizon, att, frontier, etc) have to upgrade their systems to support this, but the PSAP network has to be reconfigure and most likely new workstations deployed for the operators that support the text functions. All of this cost a lot of time and money. Source: created deployment plans for 911 provider to upgrade to text",
"It costs money by private cell providers to implement that system,. And there's no profit to be made. The only reason they would do it is if the law demanded it and the gov was going to pay to costs of it."
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5oyx7e | why is torrenting so much faster than regular downloads | Technology | explainlikeimfive | {
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"You're actually downloading multiple parts from different places (seeds) at the same time, then combining them, whereas normal download is like a single-file line."
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5ozsah | Why do mobile browsers always seem to recognize a desktop link and automatically turn into a mobile one, but desktop browsers don't recognize mobile links and convert them the other way? | Technology | explainlikeimfive | {
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"It's not the mobile browser doing it. It's the server side software. Whenever you go to a webpage, your browser is sending data to the server, specifically including the browser program name, the version, the platform. This is called agent data. Your phone browser is sending Chrome Mobile, 60.2, Android. Your desktop browser is sending Chrome, 60.2, Windows.",
"It's actually the opposite way around. Often, a site has code built into it to 'sense' what device is trying to connect. The site then sends that device what the programmers thought was the most appropriate version of the site (usually mobile). Phones can then 'spoof' their way into getting the desktop version by pretending to be something else. When you punch in the specific mobile link, and the site isn't smart enough to see if you are actually a mobile device or not, it'll just give you what you asked for."
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5p0xl1 | Why can't phone service providers offer spam filtering in the same fashion that email service providers do? | I am aware of the do-not-call list, however I have my doubts about it's effectiveness. It also seems like it would be in the service providers best interest to advocate spam filtering as it could potentially eliminate a lot of strain on phone network capacity? Thanks for any insight on this. :-) | Technology | explainlikeimfive | {
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"Because the phone companies wouldn't make money. They buy and sell on a per minute basis of a connected call. Filter out a spam call? That's a few minutes of profit not earned. Email providers don't charge per email, just a flat rate (or ad-supported fee), so they don't care if they deliver a spam message or not."
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5p3u5z | What is the difference between low level programming language and high level language? | What is the difference between low level programming language and high level language? I have no knowledge of coding/computer language at all so please keep that in mind. Also examples of both would be great. Thanks! | Technology | explainlikeimfive | {
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"It's basically how close it is to the \"real\" operations the computer is doing. For example, take a list of names you need to alphabetically sort. Using plain English to make it simpler, in a high level language you basically just say: Computer, sort the list alphabetically and the rest is handled by the in built functions of the language that convert this to machine code. In a low level language you need to be more specific, e.g.: Take the first name and compare it to the second. If the first letter is lower then put name A first. If they are the same then take the second letter... etc. Basically a high level language comes bundled with lots of operations simplified and with many abstractions that mean you don't need to be thinking (mostly) about what the computer is *actually* doing, you only think about results. Whereas a low level language needs to constantly think about how the machine is actually wired and work appropriately. To expand a little as to which is \"better\", it depends on your purpose and requirements. Generally high level languages are preferred because they are easier and less error prone, and therefore generally cheaper. Also these days performance is usually about the same because high level languages are pretty good these days at generating low level code for the computer to run. However sometimes it's possible to write a more efficient algorithm in a low level language compared to what the high level language produces. Also some devices are very idiosyncratic in their requirements and a low level language allows you to tailor code more specifically. Additionally since low level languages are typically older, they can produce code for basically any device (although this point is increasingly moot as high level languages are nowadays usually able to be compiled for just about anything).",
"Low level languages hide less from you regarding what the computer is actually doing. For example, object oriented programming is a thing. However, cpu knows no such thing as an object. It's something that you can use that doesn't actually correspond to what cpu is doing, and thus it's actually difficult to estimate, when you summon an object, to guess what exactly your cpu is doing. Low level languages on the other hand deal with things that cpu is actually doing. You'll deal with memory addresses, allocating memory, releasing memory, consider when to fetch data from ram to cpu registers and how that works out... it's not easy to write what you mean, but you know exactly what cpu is doing in response to these instructions",
"Computers read simple instructions from the application code. This machine code is quite primitive, for example \"41\" might mean \"add the number in register a and register b and store the result in register c\", \"17\" might mean \"read the number stored in the memory at the address in register d and store it in register a\". To help remembering all these numbers we mostly use assembly language which is simple translations. It is simple to write an assembler that translates the assembly commands into machine code. Then we get to low level languages. Most notably C. This is a way to simplify the process of making assembly code by adding some structure to the language. So if you write \"int a = 2*b+c\" the compiler will break down the operations into simple assembly instructions. It makes it much easier to read and write which speeds up the programming. However you are still working a lot with memory addresses and the size of variables and such low level stuff. High level languages on the other hand is an extra step away from the machine code. They often abstract away a lot of the low level stuff like how much data you can store in a single variable and where in memory the data resides. This removes a huge workload from the programmer so it is possible to work faster."
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