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63ov95 | What does it mean to unlock your phone to another service provider? And why, depending on the brand, does it cost so much and take so long? | Technology | explainlikeimfive | {
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"Most phones are *capable* of talking to other carriers that use the same networking technology. For example, in the USA, AT & T T-Mobile and I think a couple others all use the same GSM system. However, if you buy a phone through one of those carriers, they put a piece of software in place that checks who you're trying to connect to, and will block it if it's not AT & T or whoever. Why? Because they gave you a bargain/contract when you bought that phone through them, and they want you to stay inside their network. Thus they make unlocking the device and leaving their network challenging and/or expensive. If you leave, they don't make money billing you. Cell phones not purchased through a carrier company are unlocked and can be used with any compatible network.",
"Many phones are locked to a single carrier. If I have a locked Verizon phone, I can't use it with Tmobile or Sprint or whatever. Some phones come unlocked, so they can use any carrier you have a SIM card for. Some phones can be unlocked, which is simply removing this restriction in some way. It's usually expensive and inconvenient because they don't want you to buy their product and then use it with a competitors service."
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63r9xt | Why do some sites restrict how secure my password can be? (i.e. no symbols, no capital letters, etc.) | Technology | explainlikeimfive | {
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"At least in some cases it is due to legacy systems that don't support better passwords running in the backend. Legacy software is old software, for which oftentimes there is nobody around who understands how it works. Therefore it is seen as impractical to change it."
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63rhk3 | Why do CPUs have multiple cores, why not just one super core? | Technology | explainlikeimfive | {
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"because one super core is not possible. /u/Pnuttn's analogy is pretty good. There are lots of cases where it would seemingly be better if they could just get one person or *thing* to do *all* of the work, but it's simply not possible. Instead of having a hundreds of trucks delivering goods all over a city, why don't we just have one that drives hundreds of times faster? For one core to do the work of 8, it'd have to be 8 times as fast. But we're already making the fastest cores we can. It gets more and more expensive to make individual cores faster. We're at the point now where doubling the number of transistors on a core only makes it perhaps 5-10% faster. That's not worth it when those transistors could instead be spent adding a whole new core adding *twice* the computational power.",
"Think about it like this: why do restaurants have many cooks and not just one super cook who makes all the food?",
"For a long time that is how CPUs were advancing. We naturally tend to formulate programs/algorithms of sequences of things to do. So it makes sense to just have one processor going through that sequence as fast as possible. The problem is that to achieve that we need higher clock frequencies which require more power which in turn require higher density circuitry to get the power consumption into check etc. and we are starting to run into physical limits that make going further into that direction prohibitively expensive. There are some tricks other than just raw frequency increase to improve performance. For example in many cases you don't have to wait for the previous operation to finish for the next one to start if they are not directly dependent on each other. This is called **pipelining**. Think about doing laundry: you don't have to wait for the tumbler to finish before you can put the next load into the washing machine. Extending the above idea you can even process instructions written in sequence out of order or in parallel which is called **instruction level parallelism**. Eventually you have used all the implicit parallelism of your sequential algorithm, you can't increase the clock frequency of your chip anymore. So the only place left to go to is explicit parallelism..."
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63ry8i | What are the actual commands for keys on a computer keyboard? | Technology | explainlikeimfive | {
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"The keyboard utilizes a keyboard matrix circuit to enumerate each key. When pressed, a microcontroller encodes the key press event into a USB data packet and sends the signal down the wire. The USB controller in your computer buffers the signal and sends a hardware interrupt to the CPU, indicating there's work to do. The OS has a map of interrupts to handlers, so the correct handler code is given the message and acts accordingly. In windows, this is typically the task of cascading the call through all the running applications and their hierarchies of software event handlers. All keys on the keyboard are soft keys, in that their state is not fixed in the keyboard. When you press caps lock, for example, that doesn't force all key codes to be the capital equivalents at the keyboard - that mapping of key to all caps has to happen in the software. Indeed, caps lock can even be turned off in the software, which you'll see the indicator light on your keyboard turn off. If this were controlled within the keyboard, it wouldn't be able to receive USB messages that could alter the keyboard's state. So from a code perspective, we receive key press events along with other stateful information, specifically which of the command keys are also active. If you're writing software that deals with multi-key press combinations, you have to keep track of press and release events yourself, in the software.",
"> What is the difference between the Ctrl and Shift keys from a programming point of view? essentially nothing. A part of the programming that makes a keyboard work is an interface that recognises which key you've pressed 0 - 143 or whatever size keyboard you have. it then takes that, and says i've been told that key 132 means Shift. From there it then processes the functions it's programmed to do when shift is pressed etc. The keys could just as easily be re-maped, for instance if you set your keyboard to use an AZERTY config. then pressing Q, will instead produce an A even though it's the same keyboard etc. outside of that, each key you press has it's own set of instructions within the operating system which allows you to do things like copy with CTRL+C. again it could very easily be changed so that function works with SHIFT+C. but shift has other functions to worry about."
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63rzig | What happens when websites/servers go down for maintenance? | I've always wondered what the staff are usually looking for during this period. Are they looking for cache/bugs etc? Or do they change some sort of code etc they want to implement? | Technology | explainlikeimfive | {
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"also alot of times its not the actual computer that goes down but rather just the piece of software that is doing the job. be it due to upgrades, patches or reconfigurations of said software that mostly requieres the software to be restarted or even terminated while in the process of upgrading to take effect."
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63t635 | How do online retailers such as Amazon and Ebay confirm the legitimacy of their luxury items? | Technology | explainlikeimfive | {
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"In short they don't. They're just a middle man. Some of the sellers on those sites depend on their reputation. The others can use escrow or just wait for someone who doesn't care. Others, for very high end and rare items, can use escrow. This is a third company with a good reputation. When you buy the good the seller gives the item to the escrow company. The buyer gives the escrow company his money. The escrow company validates the authenticity, then sends the money to the seller and the good to the buyer. The tests run are typically spelled out in the sale contract, as well as who pays for the escrow service and other contingencies.",
"Services like paypal hold the money the buyer uses to pay for the item for a certain amount of time so if the item hasn't arrived or has seen to be illegitimate, paypal can refund the money.",
"In a way they don't. They just have systems in place to investigate potiental fraudent listings and pull them once a third party becomes concerned of them or if the listing triggers a internal coding. Also they guranntee their items where if it gets to you and you determine its fake in so many days 30-90 days if you include chargebacks. There certain standards you have to meet to sell high end licensed products. Though I'm not suee whheter this actually works beyond hassling legimate sellers. The company who owns the license or a third party can challenge the legimancy of a item. Then ebay asks for receipts and proof from the seller, if not the item is pull and it counts against the sellers record. This causes more issues for a person selling a handbag they found at a thrift store but does little to stop a seller who only purpose it is to sell items like this from china etc. They can set up a new shop easily etc. The best protection you have is to know the item well yourself and can spot fake examples. Look at photos carefully and beware of w item being too good of a deal. Once you have the item in hand check carefully and if its fake go the ebay guarantee route and the seller will have to give you a refund after they pay for your return shipping and it gets back to seller."
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63tq8x | if my camera has 15 megapixels, why can't it shoot 15 MP video? | Technology | explainlikeimfive | {
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"The way a CCD works is that every pixel will work as both a photo sensor and a tiny memory that holds one value. So when you close the shutter the content of the image is stored on the CCD itself. However then comes the hard job of dumping the content of the CCD on to further processing and storage. For a 15MP image this requires a lot of bandwidth and processing power. A lot of cameras do not have enough hardware to be able to transfer and process the entire image before the next image in the video is due to be taken. Some cameras will allow you to select between different modes that allow you to turn down the frame rate to get more pixels. But if you multiply the number of pixels with the frame rate you will see that there is a pretty constant maximum pixels per second for each camera. This is because of the hardware limitation of the data transfer and processing from the CCD to the memory card.",
"15MP = 15 million pixels. A pixel in a CCD is often 12-14 bit, which makes the frame be 15M * 12 = 22.5MB. At 30 frames per second, that's 675MB/s. No common, cheap hardware can write that fast. Even many SSDs are below that number. Current high end SD cards are about 250 MB/s, which is probably optimistic, because there are conditions that require flash devices to take more time to write than the maximum speed they're theoretically capable of. So, you need compression. But compressing 675MB/s is still quite a feat and needs considerable processing power that a cheap camera won't have. You can have high res video, [if you're willing to sacrifice an arm and a leg for it]( URL_0 )"
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63tzr2 | The implications for police and law enforcement with the decision to allow the sale of our internet histories | Technology | explainlikeimfive | {
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"text": [
"No implication. You can't buy individual people's internet histories, you can only buy anonymous data sorted by geographic region. Like 'people in zip code 90312 visited URL_0 12 million times.'"
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63u2jq | Why is there no optical video cable out yet? | There's audio but why not video or both like and HDMI cable. | Technology | explainlikeimfive | {
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"text": [
"I think the better question is why would you want an optical video cable? I don't see any upside. HDMI is perfectly capable of carrying video and audio signals and is the de-facto standard for connecting digital AV equipment these days."
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63ug3d | Why aren't there self-driving trains even though they should be easier to make than self-driving cars? | Technology | explainlikeimfive | {
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"text": [
"There are self driving trains. Most subway trains are automated. The conductor is only there to pull an emergency switch."
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640hsq | how come my phone can act as a hotspot for mobile internet but not wifi | Technology | explainlikeimfive | {
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"Effectively, what you're talking about there is using your phone as a type of router - which is pretty much what it does when it's in use as a hotspot. A router transfers traffic between two or more network interfaces - in the case of your phone as a hotspot, it uses the mobile interface (i.e. the one that connects to the cellular network) for its internet connection, and its wifi network interface for the devices that are tethering to the hotspot. There's a problem here, though - it's only got one wifi interface, and it can either connect *to* a network (to the hotel's wifi) or it can form a network for other things to connect to. It can't do both, and so you can't use your phone to share your hotel internet connection."
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640rtz | Is the Back-end same for website,desktop web applications(antivirus software for example) and mobile applications(Instagram for example) | Hello,the back-end of a website is a collection of files(If I am not wrong).Is it the same for desktop web applications(like antivirus software like Kaspersky) and Mobile apps(like Whatsapp/Instagram) too? Excuse my english and Techie knowledge,I'm an adult noob. | Technology | explainlikeimfive | {
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"generally yes For something like a website, the backend is generally one system. and the front end is designed to function different based on resolution / platform. however for something like kaspersky there may be various levels of back end system. in that you share the same log in server. however if you are on a mobile device, where you get ota updates and virus libraries from is probably someone different to where a pc gets them from. This separation allows each platform to be maintained easier and makes the overall solution a group of less complex modules rather than one very complex system."
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640xv9 | Why are androids apparently better for treating autism than fellow human beings? | I've been seeing a lot of news about androids being applied for treating children with social disorders like autism (I can send a few sources on request) and while I understand that is likely just scientists advertising a small subset of an android's potential to garner more funding, I don't really understand what it is that makes an android more qualified than a human to socialize with children? I thought it would be because they are less anthromorphic, but modern androids seem to be uncannily similar to humans in some ways (or at least, they possess highly humanlike faces) which seems to defeat the purpose of using a machine in lieu of a person in the first place. Is this just a case of technology filling in for social problems where there just aren't enough child psychiatrists? | Technology | explainlikeimfive | {
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"Robots have infinite patience, they can do the same thing over and over indefinitely. Autistic people are sensitive to changes in routine or procedure, and robots don't accidentally do that. Robots aren't replacing psychiatrists, but giving them more patient-contact time effect.",
"Other answers are correct. One more reason though. People with autism need consistency. It's more than just doing the same thing for a few days, it can mean months or longer. Behavior Therapists have a really tough job, and it's often not their only job (children with autism still go to school, meaning therapists have very limited hours they can work, and BT pay isn't great). Between juggling personal schedules, client schedules, sick days, and staff just burning out or transferring to new clients, there are often lots of changes that they need to cope with. A robot never quits, never has to call in sick, and is fungible."
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641hf8 | Why hasn't simple text modifications like italics or bold print been implemented in mobile phone texting? | It seems silly that now, where everyone has a mini computer in their pocket, I can't make a word I'm trying to emphasize over text italic. Is there some sort of restriction because of the infrastructure texting was built on? | Technology | explainlikeimfive | {
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"> Is there some sort of restriction because of the infrastructure texting was built on? Yes. Text messages have a standard amount of data they can use and that data doesn't have enough space in it to allow you to encode extra information like italics or bold etc. It would be possible to create a new standard for text messages but all the carriers and phone makers would have to all agree on that standard. What should they add? Just bold and italics? Or maybe also other features like encryption? There are lots of possibilities which makes it harder for everyone to agree. Also there are so many other ways to effective do the same thing like Facebook Messenger, Snapchat, What'sApp etc. that perhaps there isn't a big push to update text messaging."
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641sb3 | Why are residential solar panels common, but not wind turbines? Or water wheels for people who live by rivers? | Technology | explainlikeimfive | {
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"text": [
"You can buy them, but they are usually quite expensive. After all, they need to be durable in order to run for years. But the real problem is that ground level wind is a lot weaker than at the altitude that real wind turbines are positioned, so you're not getting a lot of power. I've only ever seen them being used on boats, running the fridge and other low power devices.",
"Wind turbines are all about size, bigger is more economic, not more (edit: not more of them. If a manufacturer/operator could choose, they would pick bigger size over quantity), so they're not cost effective in a subdivision. They also make a lot of noise, require quite a bit of maintenance, and space, kill birds, and are unsightly (for those who care). You can't expect homeowners to keep up on the maintenance of their own turbines, so you have to build a far less efficient model that at least won't explode in a catastrophic failure, sending blades sailing and impaling people or property. I don't think there are enough people who live along rivers to make this a viable market for a manufacturer. I think they'd be more interested in hydro turbines instead of old fashioned water wheels, but that requires building dams, which have a huge environmental impact and we're doing what we can to tear down small, privately held dams, not build more of them."
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6424as | This image of a Tomahawk Missile before and during detonation. | [Link]( URL_0 ) Why is the plane on fire before it appears the explosion has reached it? | Technology | explainlikeimfive | {
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"text": [
"The thermal pulse moves *much* faster than the supersonic blast wave and fireball. In other words, because it's so close it was subjected to an incredible amount of heat and burst into flames. Moments later it would be blasted apart by the shockwave. The separation of the \"burned\" and \"blasted\" effects tend not to be too extreme in conventional explosives, but can be *very* dramatic in nuclear weapons. See? URL_0 That burst of high energy light that hits you, in the case of a nuke, sometimes quite a loooong time before the shockwave could.",
"The explosion radiates a lot of heat (i.e. infrared electromagnetic radiation). That heat is so immense it's enough to set the airframe on fire. The reason it does so before the fireball actually touches the airframe is that electromagnetic radiation travels at a speed close to the speed of light (in air) and thus reaches the airframe before the shockwave and/or fireball do; the gaseous fireball needs to contend with flow resistance in the air, and thus travels much more slowly compared to the elctromagnetic radiation.",
"The Tomahawk carried numerous joint munitions warheads, fancy way of saying it shreds, it slices, it crushes, it lights you on fire. Ejected shrapnell comes flying out of the warhead, puncturing skin, fuel lines, delicate components, the explosive shockwave impacts the target crushing and mangling and then the explosion of the warhead reaches you, not to mention the missile's unexpended fuel creating a giant fire ball. In this picture (I'd love to hear from an actual ordnance officer) I bet the shrapnell has punctured the aircraft and/or the radiated energy from the warhead has lit the plane's paint on fire. Actually, look at the dust on the ground kicked up - I bet that's from the metal pellets shot out by the warhead hitting the dirt."
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644vao | What happens if you turn your PC off during an update when it says to not turn off your PC? | Technology | explainlikeimfive | {
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"When a computer is applying an update, it is rewriting some critical system files that contain instructions for it's basic operations. Imagine if you are writing something and someone bumps your hand or steals your paper. It would mess up what you are writing. Forcing a shut down of a computer can have the same effect. When you do this to a computer, it can't read its instructions anymore and will be unable to function normally.",
"It can corrupt your operating system. But in todays day and age, it will usually just revert back to before the update. But sometimes not."
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646h9o | Why can only one app at a time use my camera in windows? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"No fundamental reason. Software such as [ManyCam]( URL_0 ) lets you do this, as well as the opposite (combining several cameras into one big supercamera source). It's just not included free with Windows because it's not a very popular feature."
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647bb1 | Why do websites use infinite scrolling? | Technology | explainlikeimfive | {
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"text": [
"It's better for the user experience and keeping the user on the site. Repeatedly having to click and move your mouse on every page is annoying. Just scrolling to then automatically load more content is quicker and more convenient, and also encourages the user to stay on the site (in an almost addictive way, because they can just scroll and scroll)."
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647kp3 | What is the difference between Intel's i3, i5 and i7 processors? | If they were all the same clock speed, for example, what would be the differences? *edit: I don't know the correct terminology. By clock speed I meant, say they are all 2.0GHz, for sake of argument. | Technology | explainlikeimfive | {
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"Celeron, Pentium, and Core i3/5/7 are all marketing brand names by Intel. They are not guaranteed to relate to any particular hardware specification or performance. In particular a 'Core i5' in an ultra-slim laptop will usually be lower performance than a 'Core i5' in a bulky gaming laptop which in turn is lower performance than a 'Core i5' in a desktop PC. That said, there are general patterns in modern desktops and most laptops. Celeron - Two cores with no hyperthreading, no turbo boost, and a relatively slow clock speed. Pentium - Newest models, two cores *with* hyperthreading, no turbo boost, and a slightly faster clock speed. Hyperthreading makes each core 'act like' two cores, it's not as good as actually having two cores but it's better than not having hyperthreading. Older models, two cores with no hyperthreading. Core i3 - Two cores with hyperthreading, no turbo boost, faster clock speeds than Pentiums. Core i5 - In desktops and some laptops, four cores, no hyperthreading. In slightly older laptops two cores with hyperthreading. So look up the exact model! Either way Core i5's add turbo boost, which allows the CPU to run faster when only one or two cores are really being used, but slow down a little to stay cool when all four cores are being used hard. Core i7 - Usually four cores with hyperthreading, though a few laptop i7's have had just two cores. Some expensive desktop Core i7 processors have 6, 8, or even 10 cores. Again this shows how important it is to check the exact model. Some i7's have Intel's fastest clock speeds without overclocking (telling the processor to run faster yourself), but not all.",
"They're not the same clock speed. That is the difference. Also, often Intel will make them in the same batch with the same designs and everything, but the ones that have defective cores are turned into i3 and i5 depending on how many cores are bad. Some people have experienced success turning 4-cores into 5-cores by reenabling disabled cores that work. (Intel won't sell a 5-core, they'll disable a working core to make it 4-core.)"
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647xs8 | Why before USB-C technologies like HDMI, USB-A/C, etc. weren't all manufactured to work with the same port? If not at least by one company who had the patents to do so? | Edit: I meant "USB-A/B, etc..." I really am 5, apparently. | Technology | explainlikeimfive | {
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"That situation is historically grown: We started with non-digital technology where different usecases required different connectors. Usually you only needed one type of connector per use, as you e.g. had only one printer. If you needed more of a type, you could use extension cards which gave you more ports of that type. There were ports for the keyboard, for printers and scanners (parallel ports), there were serial ports to use for mice and all kinds of other devices, including directly hooking up two computers, extra connectors for sound, for the screen and... and... and... Then people started to think that was silly and started to unify. The first step was a connecter for both mice and keyboard (PS/2), and shortly after we saw the first iteration of USB: A digital, unified bus you could hook up to 127 devices (with hubs) that did whatever you wanted to do. It even brought an own power source. USB was a pretty good idea, but the bandwidth wasn't good enough for all possible cases, especially fast (external) memory as HDs and very especially for graphics. USB was a good idea, but simply not fast enough. But the unification had started. Parallel to USB getting more adopted and faster digital connectors developed, most important was DVI, which had superiour image quality over the previous VGA connectors. But DVI had one. big. glaring. issue. At least from the point of the content providers. It did not have built-in DRM measures. But the new BluRay and whatever technology required an encryption through the entire chain, from the disk to the reader to the graphics card, to the cable and monitor to keep it protected from copying all the way through. Thus, HDMI was born. A high-bandwidth, DRM-proof cable to transfer images (and the sound in one, which is pretty convenient). Meanwhile, USB developed on and besides network (still RJ45 ethernet), soundcards and high-end monitors it has taken over all connections of your PC. The next version of USB - all this applies to Apple as well and their Lightning, even though their adaption is a bit faster as they do not take legacy compatability into much account - is even faster, we can start to usefully use external memories and all the other fancy things, while many of us still hook up speakers via the small round connectors (and not USB) and we hook up high-resolution screens with HDMI and (the faster) Display Port (simply because USB still does not do the DRM-thing and is still too slow for 4k resolutions at 60 Hz). **Or, to tl;dr answer your question:** USB has not replaced all ports because we are still in the very process of just that happening after coming from a very diverse connector-past. Ask again in 10 years and we'll all be using USB-E (or any alternative) for... everything."
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6491ek | Why do automotive map updates cost so much? | I am talking about the navigation map UPDATEs. Honda's are like $150. This frosts my gord. Why does this cost this much? | Technology | explainlikeimfive | {
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"This has two parts: 1. Keeping the maps updated is expensive. 2. If you have the navigation of a certain brand, you are forced to buy for that type of device. Which means they can dictate the prices and you are either forced to pay them or live with an outdated map. In this case are milked for your money, simply because they can. There are companies where you get a livetime free update of new maps. You also need to check what updates cost when making the initial purchase of your device. And finally, you need to decide what you want to live with. Sometimes it is cheaper to get a new device with lifetime-update than updating your existing one."
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64alvs | How do traffic lights sense approaching cars? | Technology | explainlikeimfive | {
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"Some do not, older traffic lights were either operated manually or put on an automatic timer that would switch the lights in a given pattern. As the years passed on we've developed newer technology and you'll see some of them implimented on highways nationwide in large cities but older towns or smaller residential areas won't have them. The first, and most controversial, is the \"Induction Loop\". Basically its several loops of metallic wire that run an electric current to generate a magnetic field under the asphalt of the road that are an indicator that a car is ontop. As the car moves on the loop, the magnetic field changes and signals the light. I say this is controversial because lighter vehichles, vehicles with lots of non-magnetic or para-magnetic materials like carbon fiber or titanium, and motorcycles have difficulty triggering the light. Next, you have IR cameras. These Infra-red sensors basically look for and detect any heat outputs that are coming from an intersection and as there are increasing heat signatures in the same area that light gets triggered to reduce the number of heat signatures detected. Big limiation here though is that at long distances and ranges, or wide angles the cameras aren't exactly accurate and can mis-read due to weather conditions. Then you have your traditional gravity plate or weight system. Tubes or wires are run under the concrete that measure changes in weight, which creates impedance on the wire run or a change in air pressure as they are driven over triggering the light. These however need to be changed out every so often because of the sheer amount of physical stress they endure and are not practical in high stress areas.",
"There are little people that work in them and watch the traffic through the lenses. They work based on an algorithm which is focused on the number of cars at the light and the time of day. Each little person talks to the other little people in the other lights via walkie talkie."
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64b36b | How can imgur keep images forever? | Technology | explainlikeimfive | {
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"Cost? Not very high at all. Hell, a 1 terabyte hard drive cost about $50. A quick Google search says about 310,000 pics per 1 TB. 100 TB will hold about 3 billion pics. Which at normal cost of 100 1 TB. Hard drives would cost 5k. Now if you bought all that at whole sale and bought larger hard drives, tos even less money. The amount of money that imger gets from ads is way more than that."
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64cko7 | Why CPU clock speeds havent seen major increase even tough we made major improvements on nm scale? | It's always around 2.8GHZ to 3.5 GHZ. Why there are no 10GHZ or so? Please explain thank you :) | Technology | explainlikeimfive | {
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"You cannot cheat physics. Every CPU has a clock that lets it synchronize its internal workings. The higher the clock the more operations can the proccesing unit perform in a unit of time. This value cannot be infinite because of propagation delay, which is time a logic gate needs to \"open\" and \"close\". If the clock would be faster than its internal gate limit it wouldnt work because operations would be \"cut off\" by the clock cycle. Also higher clock speeds mean higher power draw and problems with internal heat dissipation. Intead of going for higher clock speeds, manufacturers go for more cores. Which means that instead of one unit doing everything very fast you have 2,4 or even 12 slower units doing the work together. This is also better when you go to smaller architectures, because instead of having the same core smaller, you just put 4 instead of 1 in the same space.",
"Computer chips work with 1s and 0s, but the actual electric signals have varying voltages. So for example a chip might consider below 0.5 volts as a 0, and above 0.5 V as a 1. Now the faster the clock speed, the less time there is for the signal to switch from a 0 or a 1. This can be countered by increasing the voltage supplied to the chip, but increasing the voltage makes the processor use more power and turn it into more heat. Cooling the processors down became the problem with the Pentium 4 in 2004, which reached its limit at 3.8 GHz. At that point Intel took a different direction. Instead of trying to increase clock speeds, they focussed on making the processors run programs faster at the same clock speeds. They also added multiple cores, essentially two (or more) processors in one, that could run two things at once. AMD followed the same approach. This approach has worked. A modern Core i7-7700 running at 4.0 GHz is five to twenty times faster, depending on the program, than a 12-year-old Pentium 4 running at 3.8 GHz.",
"Thank you all, I learned many new things !",
"There are three things that affect CPU clock: gate delay, heat and light speed. First, you should know that the basis of a CPU is the transistor. A circuit with transistors is called gate. A gate is just like a normal circuit, there are transistors and wires. So, the first limitation is the speed of light, in a clock cycle, the light must have enough time to move from the first gate to the end. At 8Ghz we have like 4cm to work with. Then there's gate delay (Propagation delay), which is the time for a gate to become stable. The gate delay increases with heat and decreases with more voltage applied. But not so fast, there's also voltage leak, when the electron goes through a transistor (but not enough for it to be on), which also increase heat. So we have a situation where increased voltage decrease gate delay, but increase heat, and in turn increase gate delay."
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64cl83 | Why do films from the 70s-early 00s look so much better, richer than ones produced today? | I do not know the technical terms for what I'm describing, but it seems that film and TV shot in the 70s-90s look so much better than the ones shot today...what's the reason behind this? | Technology | explainlikeimfive | {
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"I don't know if I can identify one thing that makes twenty or thirty years of movies similar to each other, but nowadays they really love to do color correction on everything. A few examples of this done obviously for artistic reasons are *The Matrix* trilogy (everything inside the Matrix looks vaguely greenish to suggest the feel of a monochrome monitor, thus a virtual world), and *O Brother, Where Art Thou* to give that dusty, old-timey feel to the '30s setting. But even movies not trying to elicit aesthetics like that do it. *Jurassic World* is a pretty bad offender. The older Jurassic Parks used a natural color balance, so you got a good mix of all colors you'd normally see. The new one, however, looks quite teal tinted, and thus feels flat for a reason that's hard to pin down. Cracked did a few writeups I tried to paraphrase bits of. You can see the full articles here. URL_0 URL_1 And the fifth item on here: URL_2",
"The problem is that technology has gotten too good. Up until the 90s, as film technology improved the movies looked better. Cameras got sharper images, models looked more realistic, special effects got better, etc. But most of that technology influenced the filming itself. Now technology has gotten to the point where a lot of movies are made after the filming as ended. Color correction, as mentioned in another comment, is basically an Instagram filter that any director can add after the fact to change the look of the movie. And as with Instagram, occasionally this improves the look while the rest of the time it is just lazy and just makes the end result look stupid. CGI allows for effects to be added after the movie, which means that actors are often working with very limited props and sets, often just wearing motion capture balls against a green screen, which makes it much harder to act realistically (Ian McKellan famously cried during the filming of The Hobbit movies due to how frustrating this became.) CGI is also very money dependent: barely adequate effects are much cheaper than really good looking effects. The other issue with CGI is your brain can tell when it is fake. For example, a computer generated face that is not exactly right enters into an \"uncanny valley\" where your brain knows something is wrong but can't quite identify it. This can work ok in a movie where a face is supposed to look like an imitation (Clu in Tron: Legacy and Arnold in Terminator: Salvation,) but looks either fake (Tarkin in Rogue One) or like a video game (the Neo-Smiths fight in Matrix Reloaded) in other movies. Also, using practical effects forces directors to take real-world physics into account, while CGI has no such limitations. You can find [lots of examples]( URL_1 ) of movies using unrealistic physics, and you brain notices and immediately calls bullshit. As a result, you are reminded that you are watching a movie and the whole scene just looks bad. That being said, it's not the effects themselves that make movies look bad, it's the misuse of those effects. Color correction is great for setting the tone in certain movies, whether it's contrasting Kansas from Oz in The Wizard of Oz or making the whole movie look like a sepia photograph in O Brother, Where Art Thou. And CGI when mixed with practical effects to ground the movie in real-world physics [looks amazing.]( URL_0 ) So really the issue is that technology has gotten to the point where it allows filmmakers to make lazy or bad decisions very easily, and when they do we tend to notice."
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64cv4u | Why are cell towers so big? | How are cell phones able to upload data to a cell tower when the antenna is smaller than my thumb, whereas mobile towers are huge in comparison? | Technology | explainlikeimfive | {
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"Hi :-) - The tower's antennas are on a higher location in order to be able to service a larger area. - The antenna transmits at higher power than your phone. Especially for data, it's more important to receive than sending. E.g. with HSDPA / 3G+, it's 3.6-13.98 Mbit/s for the down-stream, while the maximum uploads-speed is only up to 5.76 Mbit (HSUPA standard). - There are a lot of other things in/on the tower in order to service many clients. - The antennas itself are often highly directional, which means they also receive more sensitive than your little phone's antenna. *The antenna construction is more important than any amplifier or booster.* But you can't gain more power, it's always a trade for directional properties. Perhaps you've seen Do-it-Yourself WiFi antennas (Can-Tenna, Biquad). Same thing. The little antenna on your router sends all over, with a directional antenna you gain a lot of signal strength in one direction, while sacrificing it in another. So often the towers have multiple antennas for the same band / provider, covering segments of the area. - In the range of phone or Wifi transmission, (usually in the GHz range) antennas do not need to be large. You don't gain anything by just making them larger. While in CB or radios it did make a difference: The wavelength would result in huge antennas, and so portable receivers would use antennas at half or quarter length for example. The wave-length of 2.4GHz is 13cm for example, while for radio it can be several meters ([table]( URL_0 )). But construction directional antennas will make them larger. For a omni-directional antenna in your phone, a couple of copper-traces on the phone's circuit board or a wire inside the case will do. Making it longer would not gain anything. Making it directional would require you to point it at the tower. - All in all, if possible, two phones at 1 mile (1.6km) distance would not have as good as reception as phone < - > tower at the same distance. Just as a side-note, my mother lives in an area where there is no cable/DSL available, nor is there a highspeed cellphone tower anywhere near. I've set her up with a biquad antenna, so now she can connect to the tower two towns further away :-)"
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64d6lf | Why do people think the moon landing was faked? | Technology | explainlikeimfive | {
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"There is no concrete \"answer\" to this question. But the best explanation I've heard for this denial of established facts is that it's an expression of *boredom*. That is to say, there are a lot of people who believe that the moon landing was a giant conspiracy, or that vaccines secretly cause autism, because it's a more exciting idea than the simple truth; and believing it makes them feel special, gets them attention, and takes very little effort. They're \"in the know,\" as it were. They know something other people do not, and that gets them attention. Attention they very much want, and they can very easily get it by believing something radical. It also takes far, far less effort to believe in a fake moon landing than to actually learn the science behind how we got to space and the effort it took to get it right. So, in short, they are bored, lazy, and they want attention, and believing in something obviously fake fulfills a bunch of those issues.",
"Because overwhelming \"evidence\" exists that's been thoroughly debunked with reasonable answers and explanations. Also, the fact that only Americans seem to have this belief is a rather big case for why the moon landing is probably real. If there was any chance of it being fake, the USSR would've been all over trying to prove it was fake.",
"Here's the thing with conspiracy theories: Let's say I'm not too smart. Let's say I didn't do too well in school, didn't end up in a particularly good career and generally get looked down on. But here's the thing, right? You see all those smart people at NASA? Liars. They didn't do any of that. See all those other people who make fun of me for believing that? Well, they're sheeple who believe everything they're told because they're not smart like me. They're all dumb. If only the world was full of really smart people like me and my friends on the conspiracy forums, we're the only ones smart enough to see the world the way it really is. Oh, and the reason I didn't do to well at school? Because they teach lies. Not that it matters because everything is rigged by the Illuminati, so honest, smart people like me can't get ahead. Basically, conspiracy theories are a fantastic way to convince yourself you're smart and blame all your problems on shadowy goings-on behind the scenes. Oh, and some people are just batshit crazy.",
"It is all part of conspiracy theory psychology. People who buy into these things want to think they are smart, but often lack many of the things associated with intelligence, like higher education or a job where they use they head more than their hands. They come to resent those things and to feel smart, develop an attitude about their \"common sense\" being more important than \"book smarts\". They are drawn to conspiracy theories because they are a way to show everyone how much smarter they are. > but it seems to be mostly Americans that believe this Because only Americans are going to care about it, one way or another. Part of the psychology is being provocative, so when people disagree with you, you can \"prove\" to them how wrong they are. You tell a Belgian the moon landing is faked, they probably won't agree with you, but their national identity isn't invested in it, so they won't care enough to make a big deal out of it. But if you talk about their parliament having satanic orgies (a real conspriacy theory), you are more likely to get their ire up.",
"The ELI5 answer is very simple: A relatively large percentage of our population is stupid. That's not me being insulting, its just a description of the state of affairs. Stupidity is the inability to apply reason, especially to ones own opinions or preconceptions, and a significant portion of the population is afflicted with this condition.",
"American society generally is more suspicious of authority than most other societies. NASA appearing to be an authority on space travel can be intimidating because of how incomprehensible their work can seem. NASA's descriptions also invalidate many other claims about conspiracies like flying saucers. In order to defy the authority and proclaim that their view is the correct one, conspirators invent or rationalize information which they use to explain how actual space organizations are wrong and that the conspiracy is right. If not trying to support a conspiracy, a different motivation is just trying to undermine the authority of another large and apparently incomprehensible organization, the government at large.",
"Some of the reasons I've heard: - The technology to actually land on the moon didn't exist at the time. - The US wanted to beat the USSR to the moon both because the US feared what the USSR would do if they got there first and to show dominance in rocketry and space technology. Faking it achieves the second of these goals (maybe the first if appearing to get there first stops them from going) *and* has no possibility of failure. Failure would undermine NASA's abilities and future space exploration. They believe in these arguments so greatly, they believe the US wanted to beat the USSR to the moon *so badly*, that there can not possibly be any evidence to the contrary. Any such purported evidence is part of the conspiracy to cover up the hoax.",
"Like 30 million people watched 9/11 happen live and a whole city watched it with their actual eyes happen and the idea it was fake still is a major theory on the internet. There is basically nothing that can happen that some percent of people won't decided didn't happen. There is no amount of proof or evidence that will convince them.",
"There's a type of personality that hinges on 'knowing better' than other people. If this means disputing known facts, well, that's just what people will do, because 'knowing better' than someone else means you are smarter than them! I have known several people who are like this - always being contrary, so at any given moment, they are right and you are wrong, never mind that they have to constantly shift positions to achieve this. Moon landing deniers, climate change deniers, etc, all have this in common - they have 'secret knowledge', and that makes them feel smart.",
"Conspiracy theorists tend to be people at the bottom of society - they don't have political power, they don't know people who have political power, so power and the shaping of events seem mysterious to them. And their life experiences are often negative, so it becomes easy to believe in malevolent plots by mysterious forces. And believing that they are privy to secret knowledge, that they're more enlightened than the 'sheeple' makes them feel a little more powerful."
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64e0ht | Why can we get electricity from wind on earth, but planes do not have small wind turbines to lower gas and electric costs? | Technology | explainlikeimfive | {
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"This has been answered well by other people, and as has been pointed out, it's all to do with aerodynamics and efficiency, but there is something they havn't mentioned: Some aircraft actually DO have a wind turbine onboard. Its an emergency device to provide power to the cockpit in the event of a total power loss from all other sources.",
"Planes already convert chemical energy into kinetic energy, which means some goes to waste. All the kinetic energy (during cruising) is generated to make up for that lost in air resistance. Putting a turbine just creates extra resistance and converts that kinetic (minus wastes) back into electricity, which is already generated efficiently in the plane's systems. You're just making the system less efficient with any extra conversions. The reason it works on earth is because the energy in wind comes from the sun, which is going to go on being hot and bright whether we like it or not.",
"In one of those air crash investigation videos on Nat Geo, I think I remember seeing a tiny fan generator popping out from under the plane. In case the main power supply is unavailable, this tiny fan generates enough power to keep the most important components online.",
"The extra weight (and worsened aerodynamics) would in all due likelyhood consume more extra-energy than it would generate. The strength of wind energy is renewability, not efficiency. That's why the turbines are usually grouped into giant parks of wind-wheels: Single turbines just don't have that high of an energy output.",
"For the same reason you can't blow your own sail on a sail boat, or you can't pull yourself to the ceiling by your belt. A moving body cannot impart energy to itself. So, if you put turbines on a plane, you would be adding weight and air resistance which would in turn negate any gains that you are trying to make.",
"Some aircraft do, it's called a ram air turbine. This is not used in normal flight, since it's far more efficient to take power directly from the engines, but in the event of an engine failure the turbine can generate enough power to keep the most important systems running until the plane has landed. The energy to run this turbine comes from the gravitational potential energy of the aircraft as it loses altitude."
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64ev6h | Why did older CRT monitors for computers typically work in a black background with green text? | Why didn't they use white on black since that would give them a higher contrast? | Technology | explainlikeimfive | {
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"[Green P1 phosphors ]( URL_0 ) had long persistence (decay time). Amber P3 was medium persistence. White P4 was faster. Longer persistence meant your video could be at a lower frame rate without flicker. Nobody was watching videos or playing fast games, so it didn't really matter.",
"Actually, human eyes are most sensitive to the green part of the spectrum. There were white CRT and Amber for a long time. Green was normal and did seem brighter. Also, these monitors had a high degree of burn in, so that's why we have screen savers.",
"Green was easy on the eyes and cheap to implement. The same applies to amber, the other popular color in the early days of CRTs."
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64h76k | Why do video games crash and stop working, rather than produce an error and move on? | For example, if the game is told to do something with an object that doesn't exist, why does the entire game need to stop? Couldn't it function without moving the non-existent object? | Technology | explainlikeimfive | {
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"I'm speaking from a general programming standpoint, not as a game dev, so my information may be inaccurate. That being said: Programs that crash do so because they try to execute an impossible action. Either dividing by zero, accessing memory that doesn't exist, etc. This causes crashes because, if we didn't, and just continued blindly executing instructions, it could result in a worse scenario than the crash. Sure, if its trying to move a non-existent random object, maybe its not a thing that would actually disrupt the gameplay at all. But (for example) it could have been trying to activate a plot-critical quest. A crash at least lets the player start from their last save point: if we didn't crash, the quest could just not show up. Then, the player saves, overwriting their uncorrupted file with the new, unbeatable save file, and now cannot play any further in the game without restarting. A good example of this is the Missingno bug from the old Pokemon games. It didn't cause a crash, but it was entirely possible that the bug could corrupt your save file to the point you were forced to start over. If the game had crashed when this bug started happening, instead of continuing to work with unintended consequences, people may have only lost a couple of hours of progress, as opposed to their entire save file. (Note, this wasn't a \"conscious descision\" to not crash the game, it just so happened to be a bug of a type that didn't cause a crash. However, its still a good example of what happens when bugs of any sort don't cause a crash.) TL;DR: Games crash because worse things could happen if they didn't",
"In most cases, carrying on after interacting with something that's not there would result in more impossible interactions - either caused by the original missing thing or by whatever caused that thing to be missing. If you let the game keep running in such a circumstance you'll get more and more errors, and a significant chance of crashing the whole computer system on which the game is running, so games are often designed to stop rather than take the risk of starting to overwhelm all the system resources.",
"They do both; if they can move on when the error occurs, they will, but you only get to know about the times when they can't move on and are forced to crash.",
"If the game was engineered to do that, then yes it could. Games, and most other programs, are actually very fragile and have no way to adapt to anything unexpected. When the game has to deal with moving an object that doesn't exist, this is something unexpected, and so it breaks.",
"So, as a programmer, my game level might reference an object called \"Enemy_45\". In the program, I request this object. The code either tells me where that object is in memory, or, if it doesn't exist, it gives me a special value for a memory location that doesn't exist. I ask for the object at that location that doesn't exist. The default behaviour of a computer program when you ask for that is to crash. Programmer prefer this to happen, because we know something has gone wrong and we can fix it. Otherwise strange things happen and it can be hard to spot. I could write it so that I test \"If this memory location is the 'non-existent' value then don't do anything\". There might even be a good reason to do this (for example, if we allow users to create their own levels we don't want to crash, although perhaps we should come up with an error message) but usually we expect all the assets to be correct and validated."
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64i3ou | How do they measure direction while in space since there's no north, south, east, or west? | And if they use a 360 heading, what is the center point and what about lateral movements? | Technology | explainlikeimfive | {
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"It's by using the 360 degree twice. For instance; if you are in a spaceship heading directly forward, you would be on a heading of \"Zero point Zero\". If you wanted to travel to something on your immediate right, it would be 90 point zero. Of you wanted to go to your immediate left, 270 point zero. Directly up would be 0 point 90, straight down, zero point 270. So, a direction of 45 point 45 would be halfway to your right, looking up - like looking at the corner of a room by the ceiling. Those can also be expressed as \"by\" instead of \"point\", i.e \"45 by 45\" The same basic was is used on a static map - there is an arbitrary North to the Milky Way. Earth is located South of the galactic center at 0.0 degrees. Everything else is compared to Earth."
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64jk0h | Why is a telecom/ISP selling your usage information any worse than Reddit doing so? | Technology | explainlikeimfive | {
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"I don't have to go to reddit. If I want internet, I have to buy it from someone who is then going to sell my information",
"Instead of the internet pretend you're sending information via the post office. You agree to correspond with Reddit and mail them some of your information, the ISP selling your information would be akin to the post office looking at every piece of mail you send and selling that info to people."
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64kt9p | Why AC ads show mostly 24° C on their display? | Technology | explainlikeimfive | {
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"Are you from a warmer climate? 24 degrees is considered the highest 'comfortable' range for people. If you live in a warm area, the ads will suggest the highest livable temperature to seem relatable.",
"The cooling temperature for peak energy savings tops out at 24C, and the heating tops out at 26C. Since it is always displayed as that, it subconsciously convinces people to not drop their cooling below 24C, and their heating above 26C, to reduce overall load on the energy grid.",
"That is a temperature on the higher end of the range of what's considered comfortable for inside temperatures. So if it's 30C outside, the AC can bring it down to comfortable (and not energy wasteful) 24."
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64lbf5 | What's going on with LastPass? | Technology | explainlikeimfive | {
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"One of the worlds most respected security researchers (@taviso) took a look at their product and found some vulnerabilities. He responsibly disclosed them, and allowed LP to fix them before releasing the bugs publicly. URL_0 The issues were resolved.",
"The most critical (and dangerous) problem was fixed in the last few weeks, but there are still some deep security vulnerabilities in LastPass' security algorithm. On the other hand I assume that, now that the vulnerability has been brought to light, they'll be moving to fix it as quickly as possible. Overall, a password manager from one of the top-tier companies is still better than no password manager even after the leaks."
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64lfab | For most websites, when you enter your login info incorrectly, why can't the website tell you specifically whether the username or the password is incorrect? | It usually only tells you "your username or password is incorrect." | Technology | explainlikeimfive | {
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"For better security. Any information no matter how small could allow someone to game the system and brute force a login. Let me give you an example. Say that I really didn't like Joe Forman and I wanted to get into his facebook account but I don't know what his username is but I know a few email addresses he's used. Login: Jforman@. URL_1 bad username Login: Joe_f@. URL_0 bad username Login: [email protected] bad password Aha. So Instead of not knowing what was wrong, now I know that [email protected] is the right login. Now I can use other tricks to log in. I can try some commonly guessed passwords. I can go to a black hat web site and see if anyone with that email address ever had a password stolen, and hope they use the same password on other sites. I could google Joe Forman or that email, find out their birthday, maybe the name of their pet, favorite color from some questionnaire they took 5 years ago in a public forum. And I can use some of these to do a password reset \"What is your birthday? Your pets name?\" etc. Basically brute forcing an account is infinitely easier if you are able to get any pieces of information. It goes from impossible to hard, and hard is just a matter of patience and research.",
"They *can*. They just **don't**, because doing so is a security risk. If a hacker tries a username and password and gets back \"username is invalid\", they'll move on to another username instead of wasting time on one that doesn't exist. And if they get back \"password is invalid\", they know that they have a real account, and can focus on trying to hack it. It's more secure to never confirm or deny that an account exists.",
"A side point I haven't seen anyone else mention yet: While it's good to return the same error message whether the username or password was wrong, there's another security consideration to take into account here: the time it takes to return that error. Imagine you're an attacker trying to brute force combinations on a website. All you know is whether the combination worked or not and how long it took for you to get the message. If the validation code looks something like this, then you can figure out more information than they intended (bolded lines are where a message is printed): 1. Check if user exists 2. **If user doesn't exist, print error** 3. Get user's password 4. Compare user's password with entered password 5. **If both passwords match, print success** 6. **Otherwise, print error** Looking at that logic, you can see that the error caused by an incorrect username is printed much earlier than the error caused by an incorrect password. Also keep in mind that password validation both takes a lot longer than simply comparing two usernames (so long as passwords are even somewhat properly stored) and always takes roughly the same amount of time. Because of this, if you can observe the timing of your requests, then you can determine, regardless of the text of the error message, whether the username you entered exists or not. This is called a timing attack, and security experts generally recommend mitigating it by always doing every step of the verification. Compare the above logic to this logic, which isn't vulnerable to the same timing attack: 1. Check if user exists 2. If user doesn't exist: 1. Get the string \"doesn'tmatter\" from the database 3. Compare entered password to this string 2. **Print error** 3. Get user's password 4. Compare user's password with entered password 5. **If both passwords match, print success** 6. **Otherwise, print error** If you're unfamiliar with databases and how passwords are stored, just know that step 2.1 is necessary in case of a database that takes a while to respond. Anyway, in this new one, we actually validate the entered password against an arbitrary string in the case the username's incorrect and then discard the result. Because of this, it should always take effectively the same amount of time to get all three options, leaving an attacker with no indication of whether a user exists or not.",
"This practice is somewhat misunderstood as a good security practice, under the principle that you cannot know if you've tried to hack with a correct email address (or username or id or whatever.) However there are other ways to verify the email address information you're providing--notably, by attempting to register that email address. The system will already tell you if an email is in use and as such there is no real security benefit to not revealing whether it's the username or password that is incorrect. To developers out there, the best security is a strong password with good salting/hashing, and preventing people from knowing whether it was their email or password that was incorrect is bad usability that only hurts people trying to log in, not scripts that probably already know which email is being sought. Edit: Take reddit for example: I (and really bad guys) can see all of your login names.",
"Hypothetically, let's say your username is Username123 and your password is Password123. But you haven't logged in in 10 years and you've forgotten your username. So, you type in Username124 and Password123. The host doesn't know which one is wrong. It might know that Username124 does exist (someone else obviously) and that Password123 does exist but it doesn't know which one you don't know. For all the host knows, you could have forgotten your password. If it assumed you remembered Username124, and said \"would you like me to email you your password?\" And you said yes, then the host would send the password to Username124 (which is not you). So, in the end, it's just better to either answer the security questions or have them email it to you or reset it. You would be astounded at the amount of people who are like \"I KNOW THIS IS MY USERNAME\" and then after some questioning are like \"Ohhh, right, Username123, duh.\"",
"They are trying to make it harder for hackers. If the website specifies which info is wrong, then whoever's trying to hack into your account will be able to focus on changing that, rather than having to figure out which of the two is wrong.",
"I would like them to tell you even before you type anything in \"we require our password to have one capital letter, one number, and one symbol\" (or whatever their requirements are) so I don't have to spend time going through my variations of my password.",
"Security aside, because it's been addressed already thoroughly, I think this is more of a philosophical question: the computer can't know what I was intending. I provide the following info: User111 and pAsSwOrD If I fail to log in it could be because: 1) I actually meant to log in with User000 and typed its password correctly. 2) I hit the shift button at the wrong time, so the password should've been PaSsWoRd. 3) I actually wanted User000 -AND- I hit the shift key at the wrong time. So the poor computer can only know that one of those two things process is wrong, but it can't determine intention.",
"Also, there's a pretty strong argument for privacy. If I go to \" URL_0 \", and enter \"negrolax\" as a username, if they tell me \"Sorry, the password for this account is incorrect\", instead of \"Your password or username are incorrect\", then I just found out something you might not have wanted to let other people know about.",
"How could they know? If you entered a wrong password it could be the right password for some (wrong) username",
"I have noticed that Google doesn't do this anymore. First you need to enter a correct email, then a password. I guess once you have a robust login system, this security feature becomes obsolete and you can instead improve the user experience.",
"- Easier to code (something went wrong but we don't bother to differentiate the cases) - Security (getting the whole username/password combination right is harder than guess just one of these) - Privacy (people might know your usernames / emails but you don't always want them to know that you have an account on \"that\" website).",
"As many others have said, security is a massive thing. Even a little bit of information such as whether the email is right would make it MUCH easier for a hacker to get in. Something no one had mentioned yet, is that your average website does not know your login details. When you put in your login credentials, it sends them to another server, where a long complex maths equation is used to see whether they are matching your account. If ANYTHING is wrong with the credentials, be it the password or username, the other server just sends back that the login was a fail, and the original website tells you something is wrong. For more info about this check out the awesome video by Tom Scott titled \"YouTube Doesn't Know Your Password\".",
"Cause they don't know who you are until you login correctly. Some sites will tell you if the username doesn't exist, but if you enter a valid username and incorrect password, how does the site know if the username you entered belongs to you or if you entered yours incorrectly but it just so happens to be somebody else's?",
"Tommy has a tree house. Tommy doesn't want all the neighborhood kids to come in since little Jenny and little Ricky are dopes who pick their noses, so he locks the door after he goes in. But, Tommy does want his friend to be able to get in. So, in order for his friends to get in, and because Tommy likes to play spies (that's a thing 5 year-olds do, right??) Tommy gives his friends two things: a codename, since all good spies have codenames, and a passphrase, just like they always seem to have in movies. For example, little Mikey is codename Condor and his passphrase is \"firetruck red is my favorite crayon\". Little Joey is codename Falcon and his passphrase is \"I like grilled cheese with the crusts cut off\". In order for Mikey or Joey to get in, they need to say both pieces of information out loud and then knock on the door. Tommy will validate the information they provide and either let them in or deny them entry. Now, along comes little Alexa, who's been wanting to get into the clubhouse for a while because she thinks Tommy is cool. So, she walks up and says \"Salamander, cats are better than dogs\". Tommy yells: \"You shall not pass!\" (because his dad made him watch Lord of the Rings and he thought it was super-awesome, because Tommy doesn't suck). Now, what does that little bitch Alexa do? Well, she gets ready to make another guess. But, what does she guess? Does she try a different codename? Does she try a different passphrase? Or does she try a different both? Because she doesn't know at that point which part was wrong, or if both were wrong, she can't make a reasonable decision. All she can do is randomly guess a new codename and passphrase, and figuring out a valid combination could take forever that way. But what if Tommy instead says \"Wrong passphrase\"? Well, now she knows (or can at least reasonably assume) that Salamander is a valid codename, she just needs to guess the passphrase now. She knows 50% more than she did when she started. It's all about security. People trying to get into a system they shouldn't be in try to get as much information as possible so they can cut down the number of possibilities they need to try. It makes an almost impossible task much easier if you tell then which part is wrong because you've just cut the guesses they have to make in half. Oh, and by the way, Alexa can go to hell, that little poopy head.",
"Do you really want me to type your e-mail into a porn web site to see that you're registered on a beastiality porn web site?"
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64na00 | why children can't use vr headsets like the rift or psvr. | Technology | explainlikeimfive | {
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"Aside from the \"small necks bearing a weighted helmet\"-part... VR changes a person's spatial coordination - that ability to just *know* where your limbs are without looking at them. From touching your nose to just navigating around furniture, knowing where your body ends is important. Physical safety aside, one of the concerns is that children and their developing brains who spend too much time with a headset on may have prolonged issues with their coordination that could, in the short term, cause them to hurt themselves. In the long term, it may affect proper development. Adults tend to recover quickly from this problem (still... am surprised the \"don't drive after VR\"-crowd isn't making noise.) Children are a bit slower. I'm sure we'll have unwitting parents who will provide us all the case studies imaginable.",
"Physically because the consumer products are calibrated to average adult sizes eye seperation. This is called interpupillary distance. If the eyes are closer than the IPD of the device, then the eyes are not in the focal spot of the lens.",
"From what I've seem so far, it wouldn't hurt to allow a child, say 8-10 years old, a 5 minute try as long as it doesn't become a habit? And that there's a good chance it would be unusable for the child due to size."
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64nw81 | Why do most software programs (web browsers, for example) display an error code that you have to look up instead of just telling you the error? | Technology | explainlikeimfive | {
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"The use of error codes is considered a good practice in programming, because it allows different errors to be strictly defined and distinguished from one another. The name and explanation of that error can then be easily localized. For example, HTTP error \"404\" has a detailed specification indicating when it should be issued. It happens to be called \"Not Found,\" but a web site may choose to return a page with a different name and an easy-to-understand explanation if it wants to. Or a browser can choose to provide that information, even translate it based on the user's language. Either way, behind the scenes the web server and browser both understand just what is meant by \"404.\"",
"Going against the grain of most here - as a software developer and a person experienced in software QA, I think it's bad practice to display an error code. When I'm writing code and dealing with catching errors, I generally display a human readable message about the error (easy for the consumer to understand) and often include the error code somewhere in there for a consumer to google. As for other devs working on the same codebase, I always print the localized description to the console so that when replicating bugs, they know exactly what's going on.",
"The error codes are not really for the users. They are for the application programmers and for programmers who write software that interacts with that application. The codes make it easy for diagnostic tools to track the errors. There really isn't a need for the code to explain in plain English what the issue is when it happens.",
"In addition to what others said about users not being able to fix and therefore not really caring specifically about teh error, there's also the fact that other programs consuming the program you are using will look for those errors to handle them in specific ways. But they can't parse your error *message*, they need something easier to parse and more unique than that. Let's say the error was \"Page could not be located\" and you set up your browser to show a certain toolbar on invalid pages. Now let's say you decided to change the wording a bit to \"Page not located or inactive\". Now all the code that was looking for your previous message has to update. By using special codes, it lets you change the human-readable side of things without impacting any consuming code.",
"There are a few reasons: * unhandled standard errors - some web sites have [custom 404]( URL_0 ) pages, while some let your browser handle it * non-standard errors (getting a strange error like 452 on a web page). Your browser won't know what that is * avoiding giving implementation details - ERR #587. It doesn't want to say \"Joe's code broke\" * easy debugging - when you click too much on menu X and it crashes, it might give you error \"mX5clk\". When you talk to customer support, they can quickly give you advice"
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64oinn | How does YouTube keep up with storage space if there are roughly 67 YEARS (300h/min) worth of videos uploaded every day? | Technology | explainlikeimfive | {
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"[Big warehouses filled with hard drives]( URL_1 ). A lot of that content being uploaded isn't great quality and so it doesn't take up much space. The very high quality videos are compressed to take up as little as possible. As long as they can add hard drives faster than we can consume it, they stay ahead. Remember that the server farms are distributed throughout the world. There is probably one near you. [Check out this video by Google]( URL_0 ) [1:45]",
"An interesting thought, I'm wondering if these server farms, and not just ones owned by Youtube, will be targets in war in the future just as libraries and museums have always been throughout history. Hmm...",
"STORING the data is actually the easy part. The fact that you can type in some obscure TV episode from 1996 and have it play virtually instantly is the real marvel. For that you need a lot of robust engineering / algorithms to index, find, and present that so efficiently.",
"What the hell are we gonna do with all these videos? Are we gonna just continue to make, upload store videos indefinitely? Cuz that's gonna be a lot of videos.",
"As someone who works for a storage company, this makes me smile. \"Petabytes are the new terabytes.\"",
"Very efficient compression, the use of massive server farms, and active deletion of dead, unused, unviewed or unpopular content. Videos from banned sources are constatnly being deleted or removed from acounts as fast as video is put up. What they don't tell you is how much is being deleted. You may have X uploaded every day, but how much of X is removed to get Z? X-y=z. You could have 60Y of programming however 45Y gets taken off, so only 15Y of programming get added over the course of a day."
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64q6uh | Why do LCD screens go dark/light when looked at from different angles | Why do LCD/LED screens go dark/light or colours invert when looked at from different angles? | Technology | explainlikeimfive | {
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"When the light exists the screen it comes out at specific angles in order to form the picture. Observing the screen from a nonoptimal angle changes the amount of light that hits your eyes, causing the screen to appear darker or miscolored. The pixels from the LCD screen will always depart at a specified angle, typically straight out from the screen, unlike the large monitors we used in the past, which were more similar to projections."
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64qr3j | what is "A computer", what on an electronic level makes electronics into a "computer" can anyone build a computer? could someone build a computer without using prefabricated components in 2017? | Technology | explainlikeimfive | {
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"First, let's establish something a lot of people get wrong: in electric circuits, negative flows to positive. Electrons are negatively charged, and the negative side has an excess of electrons, the positive side has a deficit of electrons. The reason everyone gets this wrong was that the early pioneers of electricity got it wrong, and they wrote it down as such. Modern electrical diagram symbols come from an era of this mistake and it's never been corrected because we're so entrenched in the established conventions. The arrows on these diagrams are the opposite of which way the electrons physically flow. Let's talk electric components... There are metals whose properties can be described as P type and N type. I believe this basically means they have a deficit of electrons or an excess of electrons in their outer most electron orbits. If you take one metal of each type and bond them together, you have yourself a PN junction, or by another name we call it a \"diode\". You've heard of these before; for example, who hasn't heard of an LED? A Light Emitting DIODE. This component has a very interesting property - electrons will flow from the N side to the P side, but not the other way around! It's a one way electronic valve. Now, if you make a PNP or an NPN junction, you have a transistor! I'm a bit fumbly about how these things work, but the idea is current wants to flow from one side to the other, but it gets stuck unable to cross the middle. So by putting a small current on the middle, you can allow current to flow across the ends. There are clear explanations as to how bias and whatever make this possible, but you can google it. The amount of current that flows across the ends is proportional to the amount of current put on the middle. So if you have a large current on one side, and a tiny current in the middle, you can get a relatively large representation of the little current. You have an amplifier! So the large current comes from the wall outlet, probably stepped up through a transformer, and then your little current comes from a microphone, or a guitar pickup, or something. And this was the original driving motivation to invent the transistor for use in radio. It replaced the vacuum tube, which performs the same function but operates on completely different principles. You can do neat things with diodes and transistors, depending on the metals used, alloys in the middle, geometry, etc... A zener diode is one where electricity won't flow in reverse until it reaches a threshold - then the doors open, as it were. Noisy diodes are designed to flicker, whether they conduct in the forward direction or not, and we use these to generate noise or we sample them like digital audio and it acts as a random number generator. Transistors, too, are made for CPUs to have a fast and sharp switching on and off behavior, instead of the typical analog amplifier behavior. Transistors are organized into groups called \"gates,\" or \"logic gates.\" You can look these up if you want, but we can abstract the notion of an electric circuit to that of boolean algebraic logic. Instead of current or no current, we say 1 or 0. The behaviors of these circuits form their own boolean algebra - instead of plus or minus and the lie, you instead have AND, OR, NOT, and XOR. Just as you say \"1 + 1 = 2\", you can say \"0 AND 1 = 0\". You can look up truth tables to see how these boolean operations work. There are fancier gates like the NAND, which you may have heard of regarding flash memory or SSD's, this is just an AND and a NOT gate in sequence, so the as the above would be \"0 AND 1 = NOT 0 = 1\". These simple building blocks can be assembled to build more complex behavior. If you look at the Wikipedia article for the Half Adder, you can see how addition is physically constructed in your CPU, because you can translate the logic gate symbols to circuits. A computer is capable of computing any computable number. Say that 10x fast... A computable number is a real number that is countable (most real numbers are uncountable). There are other properties of what a computable number is, but it gets mathy and over my head. 7 is a computable number, Pi isn't, as it can't be represented exactly by a computer - the best we can do is represent an approximation rounded to some decimal and call it good enough."
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64qyud | What was added to black and white cameras to show color? | Technology | explainlikeimfive | {
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"Early film consisted of a thin coating of gelatin mixed with silver bromide or silver chloride. These chemicals, it was later found, separate into individual ions under exposure to blue-UV light. This chemical change can be exploited in the developing process by adding various chemicals that bind selectively depending on how exposed the items are. Initially, these chemicals were black or brown (giving black-and-white or sepia images). To show colour images, chemists needed to find both chemicals sensitive to red, green and blue light selectively and developing agents capable of representing these colours. That is, you need a red-sensitive chemical in the film and a red developer that binds only to the red-sensitive chemical (without interfering with the green and blue). Circa 1855, such chemicals were indeed found. (source: URL_0 )"
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64rpap | Why can't my phone's camera take pictures of my monitor in normal colour? | Technology | explainlikeimfive | {
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"Because your monitor's color is a trick. If you grab a magnifier and look closely, each pixel is a red, green, and blue light. The dots are small enough that your brain blends them together, but a phone camera uses a CMOS sensor that isolates each pixel in the frame of the image, and since it won't line up perfectly with the pixels of the monitor, they may catch a little more red, blue, or green. URL_0 URL_1"
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64shru | How is using a VPN for anonymity different than using a VPN for remote access to a network? | I see some people subscribing to a VPN service to remain anonymous online, but then I also here people say " I am VPNing into work so I can work from home". Is this the same thing or are there different types of VPNs? | Technology | explainlikeimfive | {
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"It's essentially the same, with a different purpose. The way the internet works is there's only so many public, internet routable IPv4 addresses. They are predefined. There wouldn't be enough of them if all the corporations and private devices to have their own IP address. So what happens is that we use a process called NATing (network address translation) to hide your device's IP address from the rest of the world and use a private IP address. To do this private IP addresses are within predefined ranges, and are not internet routable. You need to go through a router or firewall via it's public interface to gain access to those private networks. To gain access to those resources you would need to create a tunnel from one use in their private network to another location in someone else's private network. This is what you do when you VPN into a work account. You are using a tunnel that connect to a remote device that has access to resources in their private network. Common practice for a VPN is to secure this connection because it is likely going over unsecured network devices to get there (like public wifi or over the general internet). If you're using an IP address for anonymity you're basically doing the same thing. You're creating a private tunnel to a device that your VPN provider is managing and using the VPN device to access a network (in this case the public internet). When you do this your final destination sees the source of the traffic request as the VPN node you are tunneled into, NOT your local device. So you are anonymous to the destination device, but not to your VPN service. In theory, theory law enforcement or the government could pull logs or monitor your VPN service and trace back your traffic to you. But, the private destination you are seeking likely wouldn't have direct access to that information and be able to identity your local device and where you are since they don't have the public IP address assigned to your modem/router by your ISP."
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64sk4v | Why is there different Netflix content for different countries? | Technology | explainlikeimfive | {
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"Studios that sell content to Netflix want to maximize their profit. Because of copyright laws and agreements, Netlflix can negotiate with each studio to acquire specific streaming rights and agreements in each territory. Often, certain countries control territorial rights to content. So American networks can't sell directly to Canadian Netflix. Some of it is based on research as to what what works well in a particular country. But, essentially, rights holders control content for their specific territory in most cases. So each time a show gets added to Netflix, the rights have either been renegotiated with the main rights holder or the rights have been granted to a secondary rights holder in another territory who has then done their own deal with Netflix. I tried to make that sound as simple as possible but when I re-read it, it still sounds unnecessarily complicated. I tried! Source: I work for a Canadian Broadcaster and negotiate deals for Netflix distribution.",
"Contracts! In many cases the studios have already sold all distribution rights for certain countries to various foreign distributors or other comapanies, so Netflix will have to get a deal with THOSE FOLKS instead of the original studio."
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64sonb | Why are all objects in a game pink when their texture fails to load? | I have noticed that objects in a game are pink by default when their texture fails to load. I noticed it when using Unity framework or even in games developed using other frameworks. Is there a particular reason for this? | Technology | explainlikeimfive | {
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"Generally stuff the player is never supposed to see is made really bright colors/patterns that would never actually be anything in a real game. This way, it's easy to notice when it sneaks in, and it's easier to troubleshoot. Otherwise you might not notice something wrong and it might actually make it into the game that way"
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64tsjw | How far into space can we go before video or voice transmission would cease? | Even if the home base would not be on earth, what is the distance, if there is any, that would stop communication. | Technology | explainlikeimfive | {
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"No distance would be too far. The only limit is the lifespan of the people trying to talk to each other. All forms of light travel at the speed of light. This includes radio waves, which is how you might communicate. If you broadcast such a signal, it will travel out into space forever and ever. However, if you're trying to talk to someone who is 1 lightyear away, it will take one year for the message to arrive. And a further year for their message to make it back to you. Move the speakers further apart, and it takes even longer. Imagine asking a question, and then telling your descendants to wait around for the answer.",
"What you have is the inverse square law URL_0 basically the further you go the more power you need in the transmission for a general broadcast. This means so long as you have the power the distance isn't a problem. The power can be reduced by focusing the transmission rather than using a general broadcast.",
"That's hard to say. 40 years ago, the idea of receiving and sending a signal to a satellite 22,000 miles away with only a 12 inch wide dish would have been unthinkable. Dishes back then were at a minimum, six feet in diameter. But things evolve. So 100 years from now, things that seem impossible will be commonplace. Signal strength at great distances might not bother us at all. The thing we cannot change is lag, the farther away you get, the longer the lag, so there will be an ever increasing lag between when you speak and the reply. The Voyager spacecraft is the farthest human object from earth and it takes 17 hours for it to receive a message from earth.",
"Short Answer: REALLY far away. Long Answer: video and audio transmission have something in common with visible light: they inhabit the electromagnetic spectrum, waves at which travel at the speed of light. While the wavelength can shift at further and further distances away, they could still, in theory, be perceivable at great distances. Reaching in a timely manner, or having two way communications, is another issue. Conclusion: you could receive communications from millions of light years away, in theory. However, there is something \"in\" the universe which travels faster than the speed of light: the universe itself. Outside of the Local Group of galaxies, of which we are apart of, we could never reach any other place, even at light speed, due to the expansion of the universe. This, outside the local group, video and audio communication is impossible, from what we understand."
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64u9eg | what is the difference between the internet and the www? | Technology | explainlikeimfive | {
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"The Internet is like a telephone system for computers. It's a communication network that allows computers to talk to each other, much like people can talk to each other over the phone. Whereas the WWW is one of the services you can use the internet for. Your browser can requests pages from web servers, and web servers provide them, using the Internet to communicate that request and response. Think of it like calling a tourist info line. The phone system you use to make the call = the Internet, the person at the other end of the call providing you information = the WWW. And just as there are many other reasons you might use a phone, there are lots of other services provided using the Internet to communicate (e.g. e-mail, instant messaging, online gaming)."
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64vtp9 | Why do video games have leftover or unused content in the data? Is there a purpose in leaving it in? | Technology | explainlikeimfive | {
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"Towards the end of a development cycle, caution is the name of the game. Video games are really complex (and often somewhat haphazardly put together), so *any* change risks breaking something. If you're two weeks away from launch, the last thing you want to do is break stuff, so you play it safe, you don't make *any* change unless you are absolutely certain that it is (1) safe, and (2) necessary. So assets that turned out to be unused? Eh, leave them in, they do no harm that way. This is also why games sometimes ship with entire levels removed, or with very obvious bugs left in. You're near the launch date, and yes, you know this is a bug, and yes, you're 90% sure fixing it is safe and will break nothing else. But... what if it does? You don't have time to re-test everything else, so you have to ask whether leaving in a known bug is better than fixing it and risking breaking something much more important *that you won't even have time to discover before release*. Or you found a single tricky bug in this map and you just don't have time to fix it so.... just disable that map entirely.",
"A big reason to not delete content you aren't using is to avoid breaking your game. A lot of games use assets in multiple places, and as the game gets bigger the interconnection can get very complicated. If you aren't completely certain taking something out won't effect something else, it makes sense to just leave it.",
"This comment is in response to those who say \"JUST FIX EVERYTHING\". Kinda just pasting my comment from another thread lower down. Spent too much time typing this. It's all in the severity of the issues and for the higher ups to perceive said issues as \"bad enough\". Producers don't usually understand the severity of things unless they're extremely obvious. Thankfully, even though I'm only a QA Lead, I'm in a position where I can actually voice my concerns for the bugs on the more minor-but-annoying side. We call this kind of stuff \"User Pain\". As in, a typo isn't that bad or annoying. No one would just drop the game and stop playing, send us hate mail, etc, because of a typo. But a looping sound bug, although not game-breaking, could be annoying as hell for players. Every single game ever released (save for maybe, Pong) has had bugs. It's just some are a lot worse than others. Hypothetical Situation Time: Let's say it's the last day of work on your game before it's \"Too Late\". You find a typo in a side mission. Do you delay the game a month or two for that? That means paying whoever is left on the project for another month AS WELL as the PR shitstorm for the pushback and blablabla. That's a lot of time and money. But I used a small issue on purpose. Another small issue that no one gives a shit about would be like assets clipping into each other on a small scale. Could happen throughout the whole game, as long as it's not jarringly obvious it's really not that bad. I'm talking about stuff like you look at the table and it clearly combines into the floor instead of being on-top of it. Stuff like that. Next is a medium tier. So let's say you have the same amount of time left before it's \"Too Late\", except instead of a Typo, it's... When you're on the last level, if you happen to close the game while in the middle of a cutscene, when you reboot your game, the cutscene is skipped and you can't watch it again. Kinda sucks. Kinda. This is worse than a typo, but still, it's very specific (For this example, let's just say it ONLY happens on the final level, during that specific cutscene). Delay the game? Probably not. This is something that can go in the Day 1 Patch or Day 15/30 or whatever. Last example. Last day before \"Too Late\". You're on the last level about to beat the game and 100% of the time, when killing the final boss, the game crashes. So you do it again just to be sure and yes, 100% of the time, no matter what, the game crashes. This is out of the ordinary since QA would've caught it (or people are about to get fired), but for the sake of the story let's just say they didn't. This is delay-worthy. Another major must-fix would be legal issues, but those do not cause User Pain (generally), but producers are 100% going to fix. **Extra Tidbit:** Bugs usually have classifications such a S-Bug, A, B, C-Class. S is must fix. C is Typos, clipping art, stuff like that. User Pain is something we started a few years ago, which is a 2nd classification we use in tandem. So we could say \"The game has 0 S-Bugs! We're pretty good to go...But it has 3000 C-Class still.\" The producers don't exactly care about the C-Class. But now that we've opened them up to hearing what User Pain actually means, we have formulas for bug types like Audio Looping and stuff like that where we say (paraphrasing) \"Yeah, but this B-Class bug has 90/100 User Pain. Literally everyone who buys the game is going to hear it\" and they can rethink their position on the bug. Games nowadays and always, to be honest, but now more than ever, tend to be super complicated in so many aspects that it's impossible to even *FIND* all the issues, let alone fix them. Think of this: A game is tested by a team of 40 testers for 40 hours a week (lol) for let's say 2ish years. If it's a big game (AAA, million copies sold, etc), within the first 2 hours that it has been released, it has been played by the public for more hours than it was tested throughout it's whole testing cycle. There are things that you guys do that we didn't think of. There are so many possibilities. It's mind blowing.",
"There might be a forgotten piece of code somewhere in your game that calls the unused content. If you remove it and it does that your entire game will crash. So to remove unused stuff you need to go through your entire game and check to make sure nothing calls the unused thing before you can remove it. Or you can leave it in. Way easier and way safer.",
"I can answer this in the context of Age of Empires by Ensemble Studios between version 1 (AoE original) to version 2 (AoK/C) alpha, beta, release, and AoE2HD. AoE (version 1) was heavily polished with little to no leftover assets within the data or code structure. This cannot be said the same about AoK (version 2). This really came down to how rushed AoK was compared to AoE. Given the day and age of the 2 games, there wasn't really a proper way to clean up assets or remove them. Nothing was brought to 'modern' standards when the format got upgraded from AoE1 to AoE2. Storage space was no longer a big concern, yet the spaghetti ('stuff everywhere') conventions were kept. The amount of AoE2 alpha and beta assets left in is perhaps 1/6th of the entire dataset. Much of them only show up in a re-polish for AoC (the expansion), or are little easter eggs for us dataminers to find. Some don't have proper animations, bad transparent backgrounds, or come from the immediate AoE1 dataset just for testing. SkyBox labs (AoE2HD devs) have done a decent job trudging through the original source code. Including working with reversed-engineered tools to the point where the entire asset blob database (where assets are actually stored) has been exploded (extracted) and used on the fly. Some of the graphics (mostly background images) have finally been updated to modern conventions, yet the engine palette is still low-res color, because all sprite assets use a single palette*. *There's multiple palettes for game objects, each share their own global palette, but really there's only 1 important one. Also there's a engine code fork, recoding of the original, that Lucas Arts got back in the day, a little more polished than what AoE2 (AoK/C) is capable of. But the spaghetti conventions still reside within. tl;dr Don't look into the asset database of AoE, there's a generational programming gap of etiquettes on display.",
"Removing the data is extra work. If it does not do harm the game itself, the best bet is to leave it there. These days game sizes mean almost nothing, big or small. With big games, proportionally the unused content takes up a small space. With small games, even with extra content, the storage usage will take up small space anyway.",
"Fear of breaking the entire game mostly. Imagine if some low level artist removed the 3D model of the Blargg from Super Mario 64 and it broke the whole game, and they had to push the release date. That dude is fired for sure and the game might make less money. Better safe than sorry and leave it in.",
"Its everywhere in programming like this. You build a database with lots of things programmers call \"resources\". It contains pictures, strings, music. All kinds of stuff that is no code. Depending on the programming environment, the age of the project and also the management this database grows like weed and most of the time nobody cares about cleaning it up. The reason why is easy explained by an example: You have 5000 pictures, but you only use effectively 1000. So who wants to check 5000 pictures - often even manually - which pictures are used and which are not? So most teams think \"there may be 200mb unused data on a 5 gigabyte installer. So what? Why should we invest even a hour of work to clean that up? Nobody would care anyway.\"",
"i read thru the comments and still don't understand what is meant by unused content? can someone ELI5 what an example of that content is, and how a regular gamer would even know how to find it?",
"I'm nearing the end of a development cycle on a game that I'm making, and this is happening everywhere. The biggest reason is that keeping something in the game is generally easier then removing it. Especially if it's just in the files and maybe it'll be needed later. Also, removing it might just not really matter. What's a couple hundred lines of code out of tens of thousands(or, on larger games, tens of thousands out of millions), especially after the compiler does its magic? Maybe deleting maps, textures, etc. might save some file size, but whatever, storage space is cheap. An example from my game is that there was an entire mechanic that I developed, refined a bit, and then as I played and tested, decided to go in a different direction. The mechanic was stored in things called \"coroutines\" which are basically bits of code that conditionally run alongside the main code. When I first took out the mechanic, I wasn't 100% certain that I wouldn't return to it, I just started playtesting and iterating on the design without the mechanic. So rather than remove the coroutines entirely, I just stopped them from running. This was just a change in two lines(in fact, just adding \"//\" in front of them), and if I ever wanted to change it back, I just delete those //'s, and bam, the mechanic is back. So, sure, there's some left-over unused content... an entirely unused core mechanic of the game, that's technically in the source code. I probably could, if I wanted to, completely remove that code. But why would I? It doesn't have any negative impact on the game in any way, it doesn't break anything else, and I have bigger fish to fry. Not to mention, in this case the game is pretty small and I'm the only developer... imagine this happening on a scale hundreds of times bigger with even more involved and codependent things."
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64wifs | How good could video game graphics get before it is not possible anymore, and look exactly like reality? | Technology | explainlikeimfive | {
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"I'm not sure how many Teraflops (trillion calculations per second) is estimated to be required for that level of realism, but consider the following: * By the previous trend of computing power advancement, we should see GPUs in the 300+ Tflop range by 2027. A GTX 1080 is about 9 Tflops at stock clocks, and 10.5 Tflops with widely achievable overclocks. A Titan Xp is about 14 Tflops, with realistic overclock. * A GTX 580 was about 1.6 Tflops and produced [graphics like this at high frame rate]( URL_2 ) * A GTX 1080 can produce graphics [like this]( URL_1 ) or [like this]( URL_0 ) at high frame rate * Do note it's difficult to show a proper comparison between different games, and with compressed screenshots. You can see massive improvements, but there's great improvements in things like realistic faces and animations too. * So we can at least infer that since a ~5.5x increase in processing power from a GTX 580 to GTX 1080 made a massive improvement, a ~30x increase from a GTX 1080 to its equivalent card in 2027 should be extremely substantial. * Game performance has also been limited by inefficiencies in the DX11, and older, graphics APIs. Vulkan and DX12 remove a lot of those inefficiencies, so games could look better even on a current GTX 1080 just by building a game more efficiently. * On the other hand though, we likely need to run games at a minimum resolution of 8K (7680x4320) and framerate of 90 fps in order for our brains to be convinced it's 'real enough'. This is taken from a combination of the resolution the human eye sees in, and the research by many in the VR industry, chiefly Valve, finding that 90 fps is the critical point at which your mind feels 'presence' in VR. * Running something a 8K is 16x harder than running at 1080p (1920x1080), at the same graphics quality and framerate. Though there are potential software 'tricks' and efficiency solutions to bring that 16x down. * Note that if a card ~30x faster than a GTX 1080 is not sufficient, the progress in processing power is multiplicative, so 10 years later (in 2037 now) you'd have a card which was ~900x (30x30) times faster than a GTX 1080. Assuming computing power keeps following its long-term trend. If ~900x the power of a GTX 1080 was not sufficient for completely realistic graphics, I'd be gobsmacked. **TL;DR** Given it looks like a tall order, but we also make relentless progress with processing power, I make the prediction we could see fully realistic graphics at high framerate by 2027-ish. And I'd be 99.99% sure it will happen before 2037. ----------------------------------------- **EDIT**: Lots of interesting questions and discussions coming in below this comment too :) ----------------------------------------- **EDIT 2**: [Real ELI5 version]( URL_3 ) ;) ----------------------------------------- **EDIT 3**: I don't really know why this comment exploded, RIP my inbox. I guess this is what's it's like to do an AMA :P",
"I would just like to add that aside from GPU restrictions, there's the aspect of CREATING the assets used in game (models, environments, textures, dynamic and particle simulations, realistic animation movements etc). In general, the more detailed and realistic these become, to some degree, the more man-hours are required at an exponential rate. Despite being considered simply \"computer generated\" by most of the population, it requires an incredible amount of human input and creation and an ungodly amount of finessing and detail work. Hence while I see it very possible to have the technology to render very realistic games before long, I believe the true limiting factor will be the ability to produce realistic content to PUT into those render engines. Just my opinion. I'm a visual effects artist and professional 3d modeller. edit: wow thank you to whoever gave me gold, my first ever!",
"Unless you're pushing 80 years old, expect to see within your lifetime a level of graphics that meets at LEAST the following specifications: - Indistinguishable from 4k video of a real scene, depicting pretty much whatever actors and scenery that the game calls for. - Capable of simulating smoke, fire, water, and other fluid-based phenomena, once again to at least 4k resolution on a screen. - Capable of producing fully artificially generated sounds, incuding speech, in real time (I realize this is not really a \"graphics\" thing, but it's relevant to the whole experience). - At least 4k-resoluion virtual reality goggles, with wide peripheral field of view, allowing all of the above to be displayed for VR. Note that we have 1080p virtual reality goggles now, and the head-tracking issue is basically solved. - Some level of glove or whole-body-suit physical-presence controller technology, allowing the body to interact with the virtual world. This may or may not be capable of simulating physical sensations of touch or impact, for the user.",
"Former game developer here, I'm not sure the industry really cares - at least in my time in the industry and keeping an ear to it's direction, we don't *need* photo-realism. Games are art, and we cared about things looking beautiful, or at least cool, and had no interest whatsoever in the realism of the rendering. We only cared about the perception, particularly of the expectations of the animation. People easily overlook unnatural visuals like plasma weapons, blotchy blobby fire flickers, and *terrible* water caustics, especially because this is what gamers have come to expect. But if things don't *move* as you expect, then that's all you see. If something doesn't look as you've come to expect, that's all you'll see, and it will disrupt your immersion into the experience. Photo-realism is a goal in rendering, just take a look at some of the work done for SIGGRAPH, and the game industry will always benefit from those efforts, but a photo realistic game would be niche, and otherwise not always or even often desirable.",
"Some of the more static scenes in recent releases are almost indistinguishable from reality. They do amount to what's practically an architectural render, but it does serve as a proof of concept for what current hardware can handle. Uncharted 4 is a great example. With some clever lighting and texture mapping, some of the interior environments look stunningly similar to real life. Strategic / realistic placement of objects in the level design and an attention to imperfections and micro detail also trick us into perceiving a more realistic scene: URL_6 Other tech demos exist, such as the Unreal Engine 4, Paris Apartment. This sterile environment focuses almost entirely on lighting, texture quality and frame rate to produce a realistic scene. All the shadows are 'baked': URL_5 Of course, the challenge is much greater when rendering a dynamic scene, especially when physics are involved... EDIT: Do to the fact that this thread has blown up, I think that I'll expand a little bit. Anyone who's in the game industry can feel free to correct me -- this is just a personal interest of mine. In terms of physics and realism, I see several things that were major leaps forward and contributed to the realism that we see today. Nvidia PhysX in games such as Mirrors Edge introduced a new generation of rudimentary soft body dynamics and fluid physics: URL_1 Crysis 1, the fan favorite, was impressive for a number of reasons. Firstly, the shear number of resources in the open world added a sense of realism. After all, in real life, we're surrounded by millions of particles, plants, trees, etc. Dynamic water caustics were another impressive feat that was added later in the series, however the water in Crysis 1 was still leaps and bounds ahead of the competition. Volumetric lighting created the sun ray effects in the forests, and when you hold your gun in front of the sun. Environmental destruction both included the fun breakable palm trees, but also the completely collapsible huts, filled with physical assets. Texture mapping (parallax) gives the 3d effect that gravel, rocks and dirt have, instead of sharp polygons overlaid with stretched, 2d textures. Impressive texture quality, particle effects, shading and a number of 'fun' additions such as the water which remains on the screen after swimming, also contributed to the realism in Crysis 1. Here are just some of the effects: URL_2 Driveclub gives us a perfect example of how small details (the organic / natural way the water moves on the window) and scene atmosphere (lighting differential between the car and the environment, among other things) can contribute to our sense of realism: URL_0 Advanced geometry, high texture resolution and subsurface scattering in Star Wars Battlefront: URL_7 URL_3 ...and Skyrim mods which avoid repeating the same grass textures over and over again: URL_4 ...I might keep adding to this later.",
"To look real physics is a very important factor too. You can see the most realistic pice of cloth but if its not moving in the wind like a real one the immersion is lost",
"A lot of people talking about tech requirements when the real issue isn't pure graphical capabilities but an issue of the uncanny valley. The uncanny valley is the idea that the closer you get to truly emulating humanity the more we notice the differences, not necessarily specifics of what is wrong but you can tell something is off and get a distinct creepy feeling from it. The uncanny valley is primarily an issue of movement and animation not of actual graphical capabilities, so you could 3D model/paint a still scene that looks identical (and it could probably be argued that we already have) but when things move, they simply don't look quite right. People have tried to fix this by using motion capture which has been very successful for full body movements but the face is where we do just about all of our human recognition. Games like [LA Noire]( URL_0 ) and more recently [trailers for Death Stranding]( URL_1 ) put a huge amount of work into facial motion capture but no matter what you do eventually people will see the differences because there is only so much motion capture you can physically do. Did you record someones face moving idly for 10 hours? well some dedicated gamers have played your game for 800 hours and have seen every single facial expression he made in that 10 hours and know exactly when it loops. Did you record someone running? well your fanbase has noticed that they start their stride in one of 18 ways every time. keeping with animation issues, are you going to motion capture grass? how many unique animations are you going to have for each patch of grass moving? how many before someone staring at your grass notices the loop? since you've specified video games you have the problem of players doing whatever the hell they want and your most important goal is to stop everything from glitching out when that happens, and players will always try to do things that are not physically possible for a normal person (ever made a character repeatedly spin on their axis? people in real life can't do that) So to answer your question, i'd honestly say they will never be good enough to truly never see the difference. I don't see there ever being a point where creating a true perfect visual copy of our world will be doable, much less economically viable.",
"Probably not far.. Not sure but there have been times where I haven't been sure if it was a prerecorded video with actors or animated.",
"Its not just how the graphics look. There are other flaws like funky movement, glitchy physics and the fact that not all objects in any game behave like their real life counterparts. Like right now, with technology available today, you could recreate a football in a game that looks perfectly realistic. But almost any form of interaction would reveal that it is not real. He might not bounce like a real ball, not fly as far.. and if you try to destory it will not come apart like a real ball.",
"Why stop when it looks like reality? That's not a constraint. Computers could potentially create forms and actions that are beyond reality. By simulating unseen types of subatomic particles interactions I guess they could generate entirely new realities. We don't know everything we would be able to do if we could manipulate matter and energy at will. But future computers might be able to simulate such power. I'd say that's the ultimate limit.",
"I don't think the problem even today is a hardware limitation. There are tech demos of limited scenes that border on photorealistic. The real problem is who is going to pay someone to take the time to build the 3D models and art to achieve a dense photorealistic and consistent game world. It is far better to find a consistent art style that allows acceptable performance and doesn't take years of man hours to create. I think the budget for a AAA game will never allow for photorealism unless open source game engines can be built up to achieve it without too much investment.",
"Related question for the knowledgeable: How soon we will be able to see a 3D character put on a jacket or, say, a skirt, with the clothing then staying on (no off-screen model swap), and without body parts clipping through the layers?",
"I remember being blown away by this : URL_0 posted 2 years ago. I reckon, that if the goal is ultra realism, we can already do it. but i'll give it 10 more years to game in hyper-realism.",
"[some of the scenes from here]( URL_0 ) look just about like they achieve your goal already.",
"I'm a games developer (technical and environment artist). We're actually surprisingly far away from having photorealistic graphics in games. What you need to understand is that different aspects of a scene are easier to render and create than others, things like liquid simulation, dense grass and leaves in trees are currently the hardest physical things to get looking right in a real-time scene. Lighting and shadows is currently the farthest behind we are in games. Most lighting you see in games, even today is 'baked', this simply means the shadows are 'drawn on' and if you were able to move a wall, the shadow it cast wouldn't move. Newer games can combine real-time shadows with baked lighting and this looks amazingly real but has a lot of limitations with what you can do. Without going into specifics your average 'heavy gamer' will have about 4 - 6TFlops of rendering power which can render scenes from games like Battlefield and Call of Duty Infinite Warfare. By my estimates (and please know that breakthrough's in software and rendering techniques can change this) we'll need about 30 - 60TFlops to get a scene that is indistinguishable from reality.",
"It's already getting really close, it was almost indistinguishable in 2016. I'm guessing 5-10 years before it's everywhere: URL_0",
"8k resolution would be reasonably close to what human eyes could see. So televisions will be at that point soon. Graphics shouldn't be too far behind. URL_0",
"The first person who jacks into the central nervous system, records an adult scene, and sells it will be the richest person in the history of the species. Graphics are thinking small, tying into the central nervous system and make you FEEL and SEE things for real with your own brain, THAT is the future.",
"Has anyone really been far as decided to use even go want to do look more like?",
"I think once we hit that point and games start looking exactally like real life alot of the gaming companies will devote all their resources into virtual reality or augmented reality and making those look and feel like real life.",
"It's never gonna look quite like reality because the presention is on a 2D monitor. Have you ever watched 4k or 8k video on a monitor and mistaken it for the real world? And making it look like video is the BEST we can hope for. And that's gonna need not just enormous processing power, but enormous amounts of development time. Who wants to spend 30 hours making a glass bottle look EXACTLY like a real world glass bottle, right up seeing the faint roughness of the glass when the bottle is 2 inches from your nose? Who wants to pay that dude for 30 hours of high-level graphics work? Now imagine you're making fallout 10, and that glass bottle is just one piece of collectible junk in a world filled with them?",
"Game graphics need to simulate light interaction, just like the real world to seem indistinguishable. The technique is called Ray-Tracing. Literally following a ray as it bounces through the scene and splits etc. The catch here is getting really close to looking realistic has been achieved, but the \"last mile\" is extremely demanding. From looking 95% life-like to 100% lifelike, its an insane amount of computation that is needed. Software do this using cloud rendering etc, but on a console, forget about it. On a home PC maybe in the next 20 years, but i doubt it. Also note that a \"shader\" is a program that runs on every \"dot\" (vertex) of every item you see in the scene. The more compute intensive the shader, the better is simulates light interaction with the object. As GPUs get better, the amount of geometry in the scene is also increasing, as well as developers putting game physics an AI load on the GPU as well. So its not a question of fixed objects, and when they will look life-like, per say. For instance you can get a sphere to interact with millions of rays with thousands of bounces to make it seem near life-like, like 99.99%, right now on your GPU, but as you add more objects, you get slow downs. There is way more technical detail I can get into but thats the simple answer.",
"Here is an album: URL_0 Try to guess which one is a game and which one is a real photo",
"Sure, we would be able to handle realistic graphics eventually, but would Developers take the time to design all of the textures? Or maybe they could use like a photo tool that converts them to textures idk",
"One thing others here aren't addressing is that it really depends what you're depicting, and how you're depicting it. Generally speaking, people are harder to do than animals, which are harder to do than outdoor environments, which are harder to do than indoor environments, which are harder to do than objects. And everything is harder to do in higher definition, and everything is harder to do in motion, and everything's harder when you have to sync it up with sound. Still renders arguably already have a pretty good handle on photo-realism, even for people. A quality render of a person can look like a photo. But the moment you add movement the eye picks up all sorts of little subtle nuances that look wrong, things that are very hard to replicate artificially. With some subjects, it's easier to fake it. Racing games often look very realistic because they depict objects that don't animate all that much in mostly static environments - the only things actually *moving* are the cars themselves, the wheels and tires, and some environmental effects like dust, smoke, and so on. Cars don't have a lot of articulation, so it's easier to get them just right, because there's less to mess up in their animation. That's why some of the first games people *claimed* to have photo-realism were games like the Gran Turismo and Forza games. Still, those games generally haven't had much in the way of actual *people* in them, because the moment a person is on-screen, that photo-realism is ruined. PT, the demo for the now-canceled Silent Hills, is another good example. The game looked *very* good, but the majority of it took place in an indoor environment without much movement, and what movement there was was meant to be unsettling, so any brief breaks in realism could be attributed to this. And the final few seconds with Norman Reedus's character probably took more work to get the visuals right than the rest of the demo combined. So how far we are from photo-realistic games probably depends largely on just what sort of games we're talking about.",
"For it to be as actually realistic as reality itself, would it not need to compute every atom in the vicinity?",
"Keep in mind trying to match reality would create issues in terms of gameplay for anything non mechanical. Today, Mario jumps the instant you hit the A button. If you manage to create that perfect 3D model of Bob Hoskin, you're gonna have to introduce some lag to keep the animation realistic (press A > Bob gets his foot placement right > Bob flexes his knees > Bob jumps 0.5 seconds later). The goombas would have a field day. It wouldn't be a problem for car simulations or non-multiplayer FPS, but anything with realistic living creatures you control would be a giant pain in the ass.",
"i say biggest thing holding graphics behind what they could already be is consoles they come out and they are already out dated and unless the game is PC exclusive it has to run on consoles and even if you could make the game look much better on PC it would take a lot more money to make separate graphics settings for pc and console it would take a lot of time and money and wouldn't be worth it. also sony and microsoft don't like other versions of the game to look much better and sometimes pay the developer to keep the game looking the same on all platforms no matter how powerful they are"
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64wpup | How does a computer virus get its own code to infect new files? | Technology | explainlikeimfive | {
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"The code is loaded into memory during execution. So the virus can just read the code that is currently executing. Or the virus might get to read from the hard drive to get the code. A common programming exercise is also the quine which is code that outputs its own source code. The simplest way to do this is to include the source code in a string but with a placeholder to avoid recursion. The code can thus replace the placeholder with the source code again when it is printing it."
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64x67q | could someone explain google project of AI experiments? | URL_0 | Technology | explainlikeimfive | {
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"Google has been doing a lot of research in the field of Machine learning for the past years. Machine learning is a subfield of AI where the goal is to make computers teach themselves how to solve problems instead of devising an algorithm for the problem by human hands. AI experiments is a side product of this research, where they are using the general populace (us) to interact with their AI's, giving them a lot of data to work with and learn better from us, or just showing us what fun stuff they've been up to. It's literally just Google experimenting with their AI systems. See, in Machine learning the usual idea is that you give the computer a lot of data it can use to figure out the correct answer by examining the input data and trying to correlate it with the output data. The more data you give the computer the more likely it is that it can find a correct solution to the problem that works for any data you give it, even if it has never seen it before. As you play with the AI trough these experiments the AI is both playing with you and is saving what you do and what you give it as potential input/output data that it can use to learn and get better. You are teaching the AI by playing with it."
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64xekf | How do analog clocks work. How do they now what a second is? | Technology | explainlikeimfive | {
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"Most modern analogue clocks are still electrical; they use a piezoelectric quartz crystal to measure seconds, and tick once it's vibrated a certain number of times, usually 32,768. Fully-mechanical clockss generally use either a pendulum or a balance wheel - a pendulum has the useful property that, so long as its length and weight don't change, it always swings at the same frequency, so clockmakers can \"tune\" the length of the arm against the weight at the bottom to make it swing once per second. A balance wheel is more likely to be used in watches, where there's no real room for a pendulum, and some smaller clocks; it works by setting a spinning weight against a coiled spring, and has the same effect as a pendulum."
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64xjxg | How come we can make an AI that can beat humans at Chess on a level playing field, but AIs in computer games like Civilization can only beat humans when they have access to extra resources? | Difficulty in chess programs is scaled by AI behaviour, whereas difficulty in the Civilization series (and other computer games of that sort) is scaled by 'cheating' to give the AI less or more resources than the human player. Why the difference? | Technology | explainlikeimfive | {
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"Chess is actually very predictable game, at least compared to some. There are only 64 squares. There are only two players. A maximum of 32 pieces. Those 32 pieces are of 6 types, and each type has rigid limits on how it can move. The starting position of every piece and every type is pre-determined and always the same, so there is very little variation in opening moves (to the point where even humans can memorize all of the possible board variations after the first two moves, because there's only a few hundred). And the entire board is visible at once, so every player knows the position of ever game piece. Also, chess is a game of reduction: over the course of the game, pieces are removed from the board, which _reduces_ the total number of possible moves as the game progresses. There are never more than the starting 32 pieces. A lot of what chess AI's have traditionally done is brute force computation of all the possible moves several moves ahead and ranking of those outcomes. They can do that _because_ chess is more predictable than other games. Now, compare this to something like Civilization. There are thousands of hexes on a Civilization map. There are as few as two and as many as a dozen (?? maybe it's less, I don't recall) players, human and AI. There is no real maximum number of game pieces (although there's probably a computational limit determined by the computer's processing power). There are dozens, if not hundreds, of different types of game pieces, each of which might have a different combination of moves and attack power. The starting positions of every piece is not predetermined, so you never know where on the game map an opponent will start or will add new pieces to the game. And most of the game field is unknown for most of the game. And new pieces _can_ be added: the game is additive, with new pieces being added all the time (even as a players overall force is being reduced), meaning that the number of possible moves increases much more rapidly than in a game like chess, particularly in mid-game. tl;dr Chess is simple, so AI's can learn it. Civilization is way more complex, so AI's have to cheat to be smarter than humans.",
"The goal of AI in a computer game isn't to win - it's to present a calibrated challenge to the player. However, if you were to attempt to design the 'perfect' AI for a game like Civilization you'd first need to determine what that perfect strategy should look like. Lacking the millennia of thought about the rules of the game as you have with Chess, this would be a fairly difficult task with little reward - especially considering you'd need to redo all your work whenever a new version came out."
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64xti2 | how hard is it to test how real different fast food meats are, like what was done to find out subway only has 50 percent chicken meat | Technology | explainlikeimfive | {
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"It is virtually never a secret. If someone makes it sound like it was, look for the lie, as there always is one. For example, at one point taco bell got sued. The people sueing them claimed their beef was 35% beef at 65% filler. The lawsuit made TB look bad and some people still parrot the line 'it isnt beef' but they actually won that lawsuit and countersued for defamation. If you ignore water content, which is high in all foods, their meat is and always has been 88% beef and 12 other ingredients including seasonings, as well as oats and soy lecithen to change the texture. You may think \"woah, oats and lecithen? I don't put that in my taco meat!\" and honestly, while it isnt authentic, it actually does improve the texture. Maybe you should try it. Similarly, the 50% chicken claim is very deceptive. There is only one animal that contributes to their chicken and that is chicken. It also has traces (1%) of soy from their seasoning, and a lot of water. their lables match the results from indepent testing, and the accusers refuse to actually show any evidence of their claims. If you want to talk what portion of the meat is chicken, it is 100%. If you want to talk what portion of the total food is chicken protein, well, it may only be 50%, but you have to remember that if you kill a chicken, butcher it, and cook it normally, its going to be at least 50% water. If they were claiming 30% chicken id say 'wow they inject a lot of extra water in their chicken', but if the claim is 50%, thats exactly what you should expect. Testing such things is complicated but there are tons of labs that can do it, and I don't actually know of a aingle case where such accusations were actually meaningful. Fast food companies are aware of exactly how fake or real their food is and are very upfront about it. It maybe less real than you would hope, but it is more real than a lot of people think."
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64ya8i | Why do some charging cables only work when they are bent a certain way? | Technology | explainlikeimfive | {
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"Such a cable has a broken wire inside the casing and bending it that way causes it to reconnect. The cable should not be used at all as the poor connection could result in damage to the device or for the cable to catch fire."
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64yp1v | How can entire power grids be knocked down? | We often hear about major detrimental events such as a Nuclear strike or a solar flare potentially bringing down the country's entire power grid. Please ELI5 how entire power grids can be brought down by these events? | Technology | explainlikeimfive | {
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"Different parts of the power grid are intimately connected. Small issues at one spot can cause a cascading Domino effect further up or down the chain. The Wikipedia article on the 2003 Northeast US blackout has a nifty timeline of events. All mainly caused by a software issue at a plant in NE Ohio URL_0",
"A power grid is like an electrified spider web that connects your house and millions of other houses to the power plants. There are multiple paths the electricity can take to your house, so the makers of the power try to balance the electric load (more or less) evenly across the \"web\". Now imagine that one of those paths get disabled. No problem, really, as the power makers can route the power to your house along a different path. The path adjustment changes the balance across the whole web, but it's a small impact. It's easy for the power makers to adjust and keep the rest of the web healthy. Now imagine a lot of pathways get broken, to the point that you can't just reroute power everywhere that needs it and still keep the web in balance. The number of homes on the pathway need more electricity than you can push down the path, for example. Or maybe the damage is so severe that there just isn't a path left to send power down. I've oversimplified, but that's basically how grids fail. Failures on one path make other paths break and those failures cascade to even more paths."
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64zpjd | How does a computer program uninstall itself? | Technology | explainlikeimfive | {
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"text": [
"When a computer program is running, parts of it, and sometimes all of it is copied from the hard drive to RAM. Once there, it is free to delete the what is on the hard drive and continue running. When it is done, it signals the operating system, which will remove it from RAM.",
"Mostly, it erases the files from the computer's disk drive, so the next time the operating system wants to load that program into memory, it is no longer there to load. Also, it changes settings in other files the operating system keeps, so the operating system no longer tries to look for it."
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6504z0 | How do people hack Console videogames when they don't have the ability to mod like PC's | Technology | explainlikeimfive | {
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"text": [
"A video game console is essentially a computer/pc that just outputs a visual image on a tv to display the video game being run on the console, the same way a pc does this with software on a monitor. So if you look at it like that, you can imagine 'hackers' just using a similar approach and exploiting weaknesses in the system, the same way they would when they would try to mod something on the pc!"
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65103m | Clothes I was looking at on my laptop have found their way into ads on my phone. How is this possible? | I know cookies and such store what you've been looking at so you can have ads displayed, but I thought that was limited to the device you were originally looking at them on. How did the things I was looking at on my computer somehow end up on my phone? (apologies if this is the wrong place to ask) | Technology | explainlikeimfive | {
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"There are a few ways this can be done: 1. If you have an account logged into your browsers (eg Google Account logged in to your Chrome browser) and you use the same browser and account on your phone, the maker of the browser could have logged you looking at clothes on your computer and shown them to you on your phone. 2. If you looked at the clothes on your computer, then logged into Facebook. Facebook could have checked the cookies on your computer and seen that you looked at clothes. Then when you logged onto Facebook on your phone they could show you ads for the same clothes. 3. If you were looking at clothes on Amazon while logged into your Amazon account and then used your phone (which you have logged into the same account before), Amazon would know you looked at the clothes and that you have both a computer and phone and targeted ads for the clothes at you. (This works with other accounts to like Target, Gap, or any site you have an account with). 4. (This one is a little more scary than the others) If you use your phone from home while on your home Wi-Fi. Sites can log your IP address with the MAC ID of your device. Those they can see that you visit their sites from the same address and multiple devices. Then they can link the MAC IDs to you and target ads to your specific devices. This could lead to your spouse or roommates seeing ads for items you looked at online."
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651mdt | how does active noise canceling work on earphones/headphones | Technology | explainlikeimfive | {
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"text": [
"It works by hearing what is going on around you through a microphone and then adding a frequency that is the opposite of what the outside noise is. Waves are interesting in that if you add two waves with opposite frequencies together you can cancel them out completely. For example, let's say that a number is a sound, and zero is silence. The head phones hear 1,4,3,7,2 in order to cancel those \"sounds\" out it it would add -1,-4,-3,-7,-2 in order to make each number a 0. When you get 0,0,0,0,0 you would hear nothing.",
"the headphones measure ambient noise with a mic, then generate a frequency that destructively interferes (cancels out) the unwanted noise."
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651nh2 | Why is it that all the blockbusters have gone out of business, but adult video stores are still around? | I would have thought that all video stores would have been just as affected by the internet. | Technology | explainlikeimfive | {
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"text": [
"Adult 'video' stores don't just sell videos, they frequently also sell sex toys, lubes & fetishwear. Many of the ones around here also sell bongs & pipes. On top of that, they often have \"video rooms\" in the back where people do... \"stuff\"."
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651nu4 | Why can blank CD's hold the same length of music at different bitrates? | Blank CD's come in certain amounts of time they can store (e.g. 80 minute CD's), but if mp3's at 128 kbps take up 40% of the space per amount of time as mp3's at 320 kbps, why can a CD that can hold 80 minutes of 320 kbps not otherwise hold 200 minutes of 128 kbps? | Technology | explainlikeimfive | {
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"If you record a CD as an audio CD, it *always* writes the music as 44.1kHz, 16-bit **uncompressed** audio. If the source was a low-quality MP3, you just end up with low-quality audio recorded at 44.1kHz, 16-bit. If you write it as a *data* CD, you can fit different amounts of audio on there. Many modern CD players can handle MP3s.",
"> why can a CD that can hold 80 minutes of 320 kbps not otherwise hold 200 minutes of 128 kbps? Because CD audio doesn't have a bitrate the way MP3s do. It's raw, uncompressed audio (essentially the same as a .wav file on your computer). So both the 128 kbps mp3 and the 320 kbps mp3 will be uncompressed and converted to wav format before being written to the CD, at which point their equivalent bitrates are the same."
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651ti7 | Why can't computer viruses infect modems/routers? Or can they? | Because if they could then how would anti-malware stop them? Edit: Thanks for the answers guys :D | Technology | explainlikeimfive | {
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"They can and do. Routers and modems are just small embedded computers very similar to your desktop or laptop. Most of these run modified versions of the Linux or BSD kernel. The problem with these consumer devices, along with other \"Internet of Things\" products, is they rarely get updated by the end user. That is if the manufacturer even provides regular updates. So security holes go unpatched, which leaves the door open for hackers to exploit. One common attack is to turn these devices into botnets, clusters of zombie computers. Hackers use them to launch digital denial of service (DDoS) attacks, which flood servers with junk data until they overload. Several recent high profile DDoS attacks have been launched using this method. Theoretically, these devices could also be hijacked to access data on your network provided its not encrypted. So it's a good idea to keep your devices up to date, as well as install the browser addon like HTTPS Everywhere, to ensure web encryption is used whenever it's available.",
"Modems and routers can be infected with virii/malware/adware/key loggers/etc. Modems and routers are just specialized computers. The infection route is not trivial. Most routers are updated either directly from the manufacturer or using a file provided by the manufacturer. The update route is typically from a web page that is only accessible from inside the routers network and it requires a login/password to access. By inside I mean the side all of your devices connect on. This management page is not accessible from the guest VPNs if its being used. To mitigate Man-in-the-middle (MITM) attack vectors, manufacturers provide a secured channel for the router to access its updates. Accessing update directly from the router's management page is the best way to prevent infections. Despite all that - routers and modem do still get infected. This usually happens when a user does not reset their router/modem's default password and a connected device becomes infected."
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652m6q | Why is it necessary to go to such great lengths to eliminate contaminants when manufacturing electronics like cell phones? | Technology | explainlikeimfive | {
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"text": [
"It depends on the thing you're manufacturing. With semiconductor parts even tiny specs of dust can cause failures by changing the electrical properties of certain regions of the chip, so manufacturing is done in clean rooms. With other things that are less sensitive, dust is a concern because it can cause the heating of the device to change. When electronics can't cool properly they don't work as efficiently, so dust can harm power consumption, battery life, etc. That said when you see pictures of people wearing what look like hazmat suits working on electronics, most of that protection is to prevent static from building up as shocks can destroy the components."
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652oe0 | How much damage can realistically cause Kim if he decides to press the red button? Are counter-aerial defense system from other countries advanced enough to completely prevent a nuclear disaster? | Technology | explainlikeimfive | {
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"The short answer is \"a lot,\" although it would understandably be suicidal. Excluding cyber attacks or an unlikely and unorthodox employment of a nuclear bomb, the physical damage would be largely confined to Northeast Asia- particularly Seoul and the US/South Korean forces near the DMZ. Seoul is well within range of Kim's artillery. Artillery is low-tech and reliable, and the DPRK has so much of it positioned along the border that it would be impossible to prevent significant immediate destruction in and around Seoul. His forces could easily kill thousands of South Korean civilians before being neutralized. The DPRK could also reach Japan with ballistic missiles, although the last couple decades of testing has proved their missile capability to be unreliable. They could probably land a few missiles in Japan, although it is unknown how accurate they would be. The DPRK possesses several nuclear bombs, however they do not yet have the ability to deliver nuclear weapons via missile. (To do so, a nuclear bomb must be small enough to fit on a warhead yet large enough to achieve a fission reaction.) In order to actually employ a nuclear weapon against any of its enemies, the DPRK would probably have to clandestinely smuggle it into detonation range- perhaps aboard a submarine or merchant vessel. A kamikaze-style attack via a nuclear bomb-carrying aircraft could be attempted, although any DPRK aircraft large enough to do so would also be slow enough to be easily intercepted before reaching its destination. A worst-case scenario would be a DPRK nuke smuggled out of the country via merchant vessel and detonated in a US port. However, I do not know whether or not this would be achievable. Kim also has chemical weapons at his disposal, in particular the deadly *sarin* and *VX* nerve agents. These would probably be employed via artillery shells. However, like the nuclear bomb scenario described above, and as the recent assassination of Kim's half-brother has shown, nerve agents could conceivably be employed in an unconventional manner as well. These could potentially be employed against targets far from the DPRK, as the Malaysia assassination proved, although it is difficult to speculate. It is beyond question that a suicidally aggressive Pyongyang would easily kill thousands. However, the scale of the destruction would depend on the military readiness state of the US and its allies. If Seoul, Tokyo, and Washington are on high alert- as they are now- then the DPRK would achieve less destruction than it would otherwise. Another major factor would be what specific defense capabilities those countries currently have oriented against the North (anti-missile systems, CBRN defense, etc.) For example, the US-designed Patriot system has the ability to knock ballistic missiles out of the sky, but I do not know the disposition of Patriot systems in the region or if they would be able to protect mainland Japan. tl;dr North Korea could royally fuck some shit up in the short term.",
"There are some pretty major unknowns as far as North Korea's nuclear capacity. And a lot depends on your definition of 'nuclear disaster.\" North Korea does not appear to have thermonuclear weapons, and their most powerful test had a smaller yield than the Hiroshima and Nagasaki bombs. They also are unlikely to have more than about a dozen bomb, total. They lack missiles that can reach North America, and any bomber would be intercepted over the Pacific Ocean. But South Korea and Japan are much closer, and much more likely targets. Seoul is only 35 miles from the border, and it would be difficult to defend from an attack at that short range. That's nearly in range for artillery, so in the event of war, nuclear weapons aren't the only threat, and probably not even the biggest."
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652tks | Why had USB type C become more popular than USB type B ever was? | Technology | explainlikeimfive | {
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"I don't believe that your premise is true. USB-B is incredibly ubiquitous, and type C is relatively new and not used on a lot of devices (yet).",
"Type B was extremely popular, it was/is used all the time for non portable peripherals. It was never made to fit a cell phone or anything. It was to plug in your printer before networked printers got big."
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652vai | why do wi-fi devices sometimes end up self-assigning IP (169.254.xx.xx) instead of the router's default (192.168.xx.xx)? | sometimes my devices will end up with a self-assigned IP instead of one dished out by the router. Why does this happen? i sorta understand theres some conflict but why, and am i able to prevent this conflict from happening? i usually fix this by restarting the router, but is it possible to stop it from even happening, is there a setting i have to change or set on my router or device? | Technology | explainlikeimfive | {
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"A 169.254.x.x is an APIPA IP address. This generally occurs because there was a breakdown in communication/response with a DHCP server. The usual fix is to correct any network configuration issues to ensure access to DHCP server or correct any DHCP server configuration issues. Quick and basic things to check on the network: ensure an IP-Helper command is available on all needed subnets that do not have a DHCP server on them. Make sure the default gateway can contact the DHCP server. Quick and basic things to check on the DHCP server: make sure the service is running and you have enough available IP addresses to be assigned. If this is a home network, make sure you have enough available IP addresses in your pool. If you have too much wireless congestion interfering with the DHCP process you can try a different channel."
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653awy | What's the difference between 4k LED, and OLED TV's? | Does it have to do with pixels? Are the pixels the same? Are the LED pixels rectangular vs OLED circular or something? | Technology | explainlikeimfive | {
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"OLED TVs work differently from an led tv. In an OLED panel each pixel has 3 organic light emitting diodes that light up to create different colors of light for each pixel. In an LED panel the LED part is referring to the backlight (not needed in an OLED panel). The led provides light that is filtered through an LCD panel which selectively allows different colors of light to leave the tv and hit your eyes. Both types of TVs can be 4k but the OLED will cost significantly more. The OLED panel will have deeper blacks because the pixels can actually be turned off and produce no light however in the LED panel it blocks all colors of light equally yet some light still leaks through."
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653igm | Where is the internet? How is it connected to the physical world through our computers? | If there was a global shutdown of all computers what would happen to the internet? Let's say we (as in all of humanity) transcended our physical bodies and imprinted our minds like an ai into the internet what would happen to our digital space after years of physical neglect on the outside? Im just curious, and kind of dumb. | Technology | explainlikeimfive | {
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"Every single piece of information exists on a server somewhere. The cloud isn't real it's just millions of servers physically located somewhere.",
"The Internet is just the name we give to a whole bunch of computers and communications gear connected together. If all the computers were gone, there would be no Internet -- just as if all the people were gone, there would be no civilization.",
"The internet is basically a globally interconnected network of computers. There is no \"where\" when talking about it because internet is just a term used to described this global network. However, we can look at the physical elements that make the internet possible. Typically, a network can be as small as two devices that are able to communicate with each other. For example, I can link up my computer and another computer in my house and have them communicate, which forms a network. I can add more computers to this network as long as I have the physical space and hardware to connect them. The hardware that connects them and facilitates communication is known as a router. All the computers I have connected to this router form what is known as a local area network (LAN). LAN's are essentially your home network of interconnected devices. But say you want to connect to reddit from one of those computers on your LAN. For that, you need a modem. A modem allows you to connect your local network to other networks across the globe, otherwise known as the internet. The internet is, on a basic level, a series of interconnected networks that are able to communicate with each other. There is a lot more going on that facilitates global communication but it's not within the scope of an ELI5 answer. What I was hoping to explain is that there is no real physical location of the internet as it's really just a globally connected network of smaller networks. > If there was a global shutdown of all computers what would happen to the internet? It wouldn't exist anymore. Computers are needed to at every step of the way so if they're all down, then so is the internet. > Let's say we (as in all of humanity) transcended our physical bodies and imprinted our minds like an ai into the internet what would happen to our digital space after years of physical neglect on the outside? This one's a bit more nebulous because it depends on a lot of different factors. First, remember that the internet is basically a global connection of countless different networks. That said, it depends on how the AI is stored and what kind of resources it needs. If we're imprinting all of our minds onto an AI, that would likely require an astronomical amount of data storage and processing power. This would most certainly be a networked operation as one physical computer could not handle the sheer mind-boggling load of information it would need to process at any given time. However as I mentioned above, networking computers together in the same building or area don't need to be connected to the internet, they just need to be connected to a router. If each computer in this LAN facilitating this AI shut down, so does the AI itself. Assuming this data is written to some kind of storage like a hard and/or solid state drive, then it should be safe for a good while. Of course, these technologies are susceptible to the elements, magnetic fields, power surges, and other such things, but over the long haul, assuming humans don't exist anymore because we've transcended, then they would likely deteriorate over time. So much of it depends on the media it was stored on and what kind of crap it's exposed to during its existence without us. On some level, there has to be some kind of control to maintain it and without any control, it's anyone's guess as to how long it would last without us."
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653trr | What is plant-based meat? | Was reading an article about synthetic meat and it kept mentioning "culture created meat" and "plant-based meat". | Technology | explainlikeimfive | {
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"Animal cells take amino acids from plants and turn them into proteins. Then they arrange the proteins into muscle cells and other tissues. When we kill these animals and eat them, we call it meat. Now instead of using animal cells to make our meat, what if we train bacteria to take amino acids from plants and turn them into proteins too? They already do that, but they turn them into different proteins than the ones animals do. But if we can create bacteria that make the same proteins as an animal, it would be indistinguishable from animal meat. This means a few things. Instead of having to raise animals and then kill them to make our meat, we can use bacteria to make our meat for us. This would be way cheaper, better for the environment, and more ethical than killing animals for meat. It's theoretically possible, and companies are getting closer and closer to creating it. The great thing is that not only can these bacteria made tissues be used to make food, they can also make replacement organs and tissues for humans."
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654rds | Why are most circuit boards in a dark green shape? | I know that there are other PCB colors too, as Arduino blue or SparkFun red. But most boards in industry or in home appliances are in a very specific dark green color. Is there any particular reason for it or is it just a grown standard? | Technology | explainlikeimfive | {
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"Dark green is not a shape. Assuming, however, that you meant \"colour\" - it's to do with the manufacturing processes involved. While it's increasingly possible to use alternative materials, the best-established processes use materials that are that colour. Simple as that.",
"It's not so much that the circuit boards, which are made of fibreglass, are green. Uncoated FR4 boards are a [yellowish/brown]( URL_1 ) colour. The [solder masks]( URL_0 ) that are applied to commercial PCBs often contain a green dye. It's possible to get masks of other colours but green is often the most widely available and cheapest option. I can only find speculation as to why the choice of colour. It's possible that the military required green PCBs and that that influenced the industry standard. It's possible that, of the dyes commercially available at the time, the cheapest to give pleasing results happened to be green. It's also possible that someone in the marketing department chose green and it caught on.",
"Circuit boards have two parts: a solid core and a varnish layer that serves as a mask Historically the early commercially successful circuit boards were made with a glass-epoxy core that was naturally green (although a less attractive green than today) and the varnish layer was more-or-less clear. Thus green became the color associated with circuit boards. Nowadays you can get the core and varnish layers in any color and it is not uncommon to see red or blue or other colors chosen for marketability, but since green became the default it is often cheaper or used if no color is specified."
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6563qx | Why does turning an electronic device off and on again often fix most of the problems? | Technology | explainlikeimfive | {
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"A lot of issues with stuff not working is because the RAM (or some other temporary memory) is storing some sort of issue. When you try to do something where the computer has to look at a previously saved value there is a chance the value was saved incorrectly in temporary memory. So when the computer goes back to check that value it throws an error stuff stops working. Restarting reset all the temporary memory (sometimes you have to take the battery out to fully reset the RAM) and clears that incorrect value.",
"Imagine you're an apple farmer and you're shipping your apples to market. You ship these by packing boxes onto a train which goes to the market where they are unloaded. The train comes back and you load more etc. Now you're really good at your job. You can load 10 boxes every time the train comes in but the guy on the other side is a bit slow. He only unloads 9 to market every time. Thankfully the train can hold 30 boxes at once so for a while it's fine you load boxes into the train and slowly more and more spaces get used up by boxes of apples that aren't loaded. Eventually though you're going to get to a point where there's not enough room to load your boxes onto the train and the whole process gets stuck. The train is like the RAM in the machine, it can only hold so much but you get a lot of it. You and the guy in the other end are processes running and him leaving a box on the train is a memory leak. When you shut the machine off you're stopping all processes and emptying the train which lets you send more boxes of apples.",
"Because when devices turn back on, they usually reinitialize everything back to known and sane values. The error happened when one of those values became unexpected and the device didn't know how to cope. How that value became unexpected is a wholly different topic."
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65658b | What is the difference between an object, a class, and an instance? | edit: Yes, it is a programming question. | Technology | explainlikeimfive | {
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"Think of a class as a template, where functions and fields are defined. From that template, we can build concrete instances/objects. A very simplified example: Imagine, a Person class has the fields: name and age, and address. But it has no values since it's a template (but it could have a default value defined in the template, but let's make it null just for the sake of example). To make a \"concrete\" person, you need to make an instance of a class, where you can store a specific person's name, age, and address. In practice, \"instance\" and \"object\" are synonymous with each other."
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656lc9 | Why is it that sometimes "I am not a Robot"-Captchas don't prompt you to do anything? | Technology | explainlikeimfive | {
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"text": [
"It's a mechanised risk assessment, along similar lines to those done to determine your car insurance policy. The machine looks at a number of things it knows about you, or can determine from your interaction with the actual captcha itself. For example, if you have cookies in your browser that identify you as a gmail user, then they already know quite a bit about you. If you have others that identify you as a consumer of some other Google services, then they probably know that you're a person before you do anything at all. In the case that you come in cold, without them knowing enough about you from previous Google interactions, then they can still look at your behaviour and make a fairly good mechanical guess as to whether you are human. For instance, how long did it take you to start moving the cursor towards the checkbox? What path did the mouse cursor take? In other words, did it look like a human did it, or a piece of software? Of course, it's an arms race. Machines will get better at simulating humans, and the parameters of the 'not a robot' decision will have to change. Right now we might be in the sweet spot of merely moving the mouse the cursor, but more sophisticated robot-check-defeating algorithms may overpower this in future. But for now, enjoy how easily you can convince silicon that you are fleshy.",
"Just checking the box is enough, because it tracks how you move the mouse to click on it. If it seems too \"mechanical\", that is a quick and direct click on the box, it may take you to a secondary screen to verify that you are not, indeed, one of our robot overlords."
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658tsh | Video games and source code | Hopefully there's some people here with knowledge, or better yet, programmers for video games. To preface, I'm mainly asking this about the top-selling AAA games I'm guessing that a video game's source code isn't written in a text editor. I'm aware that there's such a thing called a "game engine" - but how is source code actually developed to make the game work? Let's take Overwatch as an example. I would assume that in the game engine, you implement a 3D model of a hero (Reinhardt), will he have his own separate tab of code where the developers write his functionality right there in that game engine? It's late at night and I really don't know how to word my question. I guess I'm just looking for some insight on the process that developers go about coding their video games. How they relate their code to character models, etc. | Technology | explainlikeimfive | {
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"Computer engineer here. I'm not a professional game developer, but I can provide some insight since i do lots and lots of programming (software and HDL). > I'm guessing that a video game's source code isn't written in a text editor. I'm aware that there's such a thing called a \"game engine\" - but how is source code actually developed to make the game work? Source code is plain text and nothing more. It can be edited in any text editor, or it can be edited in an Integrated Development Evironment (IDE) that includes an embedded text editor. IDE's are awesome software suites that include a number of tools (usually including a text editor) and link them all together in a comfortable way. > Let's take Overwatch as an example. I would assume that in the game engine, you implement a 3D model of a hero (Reinhardt), will he have his own separate tab of code where the developers write his functionality right there in that game engine? In your example, Reinhardt includes both assets and logic. The assets include 3D models, textures, shaders, audio samples, etc... With the exception of shaders, these assets don't constitute \"source code\" in the programming sense. The game engine necessarily needs to understand the structure of these assets in order to make use of them; it does not however care what the contents of those structures are. Most of these assets are produced by artists with little programming knowledge, are integrated by game designers with modest programming and art knowledge, using engine tools designed by engineers with excellent programming knowledge. The engine designer doesn't care what the art assets are, the engine designer is merely concerned with making sure that the engine can interpret the art assets and make use of them and that the engine exposes the functionality that the game designers wish to have. For example, rendering a 3D box requires loading the contents of a model file, extracting its verticies (points in 3D space), constructing polygons (usually triangles) between 3 or more vertices, and then applying a texture to that face. Where does that texture come from? From another asset containing a texture image. Then, filters, transforms, and other neat things are applied. This process is more or less the same for all 3D models, from a static 3D box to a fluidly animated 3D character. Some game engines are available only in binary format. This means that the engine developers do not release the source code itself, but they do release a compiled version of the game engine along with a header file that describes how to interface with the game engine.",
"There are different jobs that do different things. Software engineers (aka coders) will typically use an IDE (integrated development environment) to design and write the base code that defines the mechanics of the game including the game engine. They will provide hooks to allow customization of mechanics but usually don't define the specifics so they can be tuned. Modelers will create the 3D models that will interact with the game engine. The engine itself just sees these as meshes of triangles with various information about how to render them. These models are created with separate tools than the IDE the game engine developers use as they need to do very different things as a modeler does not need to know the code behind the model. Models include characters as well as terrain and any other object in the world. Animators will take those models and define how the models move in the engine. Similar to the others, this may again use its own special tools customized to the task. Designers are the ones that define what characters can do what things, damage values, healing values, and all the little specific things that are often balanced, nerfed, buffed, and otherwise changed during development and after release. Sometimes changes necessitate new code to be added. Other times they can simply reuse the tools already developed to tweak functionality."
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65a5tr | the "mother of all bombs" / largest non nuclear bomb. What makes it so powerful? Why is it significant? Why use it now? | Technology | explainlikeimfive | {
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"text": [
"The [MOAB]( URL_4 ) is an air-burst weapon intended for soft to medium targets over an extended area. And while it technically is not a penetrator weapon (commonly called 'bunker busters'), it is optimized for targets in environments like caves, canyons or extensive mine fields. It is not a weapon for deep or heavily reinforced caves, but the blast size will collapse smaller vunerable caves. It's not the largest non-nuke bomb in existance, but it is the largest non-nuke to have been used in combat. Why now? If we are to believe Gen. Nicholson in [this article]( URL_1 ), ISIS have increased their use of IEDs, bunkers, and tunnels as their losses have been mounting. The MOAB creates a large blast area over the surface of the battlefield and pressure from the explosion likely detonated many improvised explosive devices. Edit: [This article]( URL_2 ) states previous combat situations have been unsuitable for the MOAB because most fighting occured in densely populated areas, whereas this time the ISIS network were spread over a largely desolate area. And [this article]( URL_0 ) has a detailed description of the MOAB design and capabilities. On further searching I have also found [this early article]( URL_3 ) about MOAB tests which explains effects at different distances from ground zero.",
"\"what makes it so powerful\"? A shit-ton of conventional explosives \"Why is it significant\" It's cool so the media will talk about it. \"Why use it now?\" To distract you. Is it working?",
"It is just a new weapon, there is nothing that significant about it. There was a very similar weapon from the 1960's that was used in Vietnam called the [BLU-82]( URL_0 ). This \"Mother of all bombs\" is just a slightly larger version of that weapon. ~~that is specifically deigned to destroy bunkers and tunnels.~~",
"The bomb explodes above ground rather than when it hits the ground. This causes the explosion to be stronger in a way that allows it to collapse tunnels underground. When a bomb explodes on the ground it is deflected upwards and outwards instead of down like the the MOAB as mentioned above."
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"http://www.abc.net.au/news/2017-04-14/explainer-what-is-mother-of-all-bombs/8444818",
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65aq3b | What is computational linguistics? | Technology | explainlikeimfive | {
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"text": [
"It is the application of computer science techniques to language. What does this mean? So saying I have the following phrase: 'The password to my account is XYZ' Computational linguistics could apply a number of different filters on this sentence They could for instance when seeing that \"password\" is present assume that one of the other words is in fact a password. They would most likely strip out filler words necessary for grammatical purposes but are largely uninteresting like \"the\", \"to\", \"is\" They could see that across many sentences, account and password often appear together and near each other. They could see that \"XYZ\" is a weird combination of characters to make a word and therefore likely not a word at all. Coupled with the computer's understanding of what a password is, it could deduce that \"XYZ\" is in fact a password. Now to what, they would need to understand what \"my\" is referring to and could use other clues to try and deduce that as well. For a human who understand english, it's very easy to parse the sentence and pull out the password. For a computer it is much more challenging and the area of computational linguistics aims to apply techniques used for solving computer science related issues to solving language ones."
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65b95l | With driverless cars becoming more common and safer, how can this technology be brought to airplanes? | Technology | explainlikeimfive | {
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"text": [
"Commercial jumbo jets are already mostly \"driverless,\" in that they can take off, fly, and land all on computer. The pilots are there to make sure nothing goes wrong.",
"It's actually much easier for planes than for cars. Unlike cars, planes have very few obstacles they have to avoid. They don't have to worry about pedestrians, and they are kept a long way from other aircraft. The only time they have to worry about obstacles is during take-off and landing, and it's relatively easy to add technology to runways to help the automatics compared to roads (because there are far fewer runways than roads, and because runways are straight lines). Almost all airliners fly on autopilot for most of the flight with little intervention. Most airliners are capable of landing themselves at the biggest airports - smaller airports don't have the relevant equipment on their runways, but the process for adding this equipment is well understood (it's just too expensive to justify). Take-off isn't usually automated, but it's relatively simple to do so. The hardest part to automate is taxiing, because airport layouts can be complex. The other thing that would have to happen is that the communication between air traffic control and the aircraft would have to be modified so that a computer could easily understand the instructions from air traffic control. From a technology point of view, there's little difficulty in achieving this. All of this already happens with unmanned aircraft every day. Most of these unmanned aircraft are owned and operated by the military, but there's very little from a technology point of view that would stop the same technology from being used in passenger aircraft. The biggest problems, though, are a) training the autopilot how to handle an emergency, and b) convincing the public that aircraft without pilots are safe. As far as emergencies are concerned, a car can simply pull over to the side of the road and stop, a plane can't. An autopilot can easily be trained how to handle any specific emergencies - the difficulty would be in teaching it how to handle an emergency that we didn't think of in advance. And convincing the public it's safe - well, that's something that might come eventually, once the public get used to driverless cars perhaps?"
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65czml | What is BitMining? How exactly do you mine for money on a computer? | Technology | explainlikeimfive | {
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"You don't really mine for money, that's just the word that's used. So with normal money, there's a central governing body that decides what is a real dollar and what is a fake one. With a currency like Bitcoin, it was intentionally designed without any kind of central authority. That's good because it means no one is in control of it. But that's bad for 2 reasons. There is no one who judges what's fake and what's real. And also there is no way to get new coins into the market. A small amount of new money is important for reasons not worth getting into here, it just is. So Bitcoin solves the fake problem with cryptography. That's why it's called a cryptocurrency. What they do is they have the entire transaction ledger of the entire world public and available for everyone to see. Therefore anyone can inspect the ledger and anyone can see that coins are legitimist or not. You can't tell who owns what coins, but the balances of every bitcoin account can be easily tracked and calculated with this public info. But doing so, that's a pain in the ass. So to get around this pain in the ass they use something called a hash. A hash is a computer term where you take some amount of data, like a book. And use a mathematical function to turn that data into 1 number. The number, obviously, will be quite large. Because of the way this mathematical function works, changing even 1 letter in an entire book will result in a totally different number. It's also important to know that it's impossible to go backward. You cannot go from the number to the book, only from the book to the number. So with Bitcoin what they do is run a contest. Every few minutes the new transactions are added to the old ledger and \"locked in\" the process of locking in the transactions is public but involves using a hash on the transaction record. A \"correct\" hash is one that results in a number with a certain number of zeros at the beginning of it. So a coin miner will take the old history, add the recent history and hash that data to arrive at a number. That number will not have the correct zeros, so it's the wrong answer. The miner then adds a little bit of random data, and hashes again. They do this over and over, millions of times until they find the exact right random data that generates the correct number of zeros in the hash. Once that is done, the miner publishes the random data for everyone to see. This means that anyone can take the old records, new records, and the published data and show that it results in the correct hash. If they change even 1 number, it will fail the test and everyone will know it's a fake. All the miners of the world then add that new transaction batch to the historical record, take the new transaction batch and repeat the process. This is how bitcoin verifies that there are no fake coins out there. All of this hashing, it takes computer power. That computer power is expensive and people would not be willing to do it if there was no reward. So as a reward when a miner finds a winning hash, they are permited to create some new coin and give it to themselves. Basiclly it becomes part of the verified transaction record. This is the reward for using your computer to do all this math, and we call it mining.",
"It's basically selling your computing power. You are loaning the bitcoin network your computing power and earning bitcoin in return."
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65daan | If the earths Carbon levels have constantly been changing throughout history, How do we know carbon dating is not inaccurate? Aren't we assuming a constant when there is none? | Im curious Since there have been periods throughout history where greenhouse gas levels have been so high at times (siberian traps) and so low at times like during the ice ages. plus other Major events that we cant even understand or know about... So my question is basically, "Isn't using carbon levels as a measurement assuming a constant when there is none?" I started getting on this thought tangent because I truly believe advanced civilizations have lived on earth for much much longer than we think. 10's of thousands of years ago, maybe 100,000 thousand. Look at the ancient maps of antarctica where they mapped the coastline under the ice with modern day p[recision. It just Doesnt make sense to Assume advanced civilizations are only 2,000-6,000 years old. | Technology | explainlikeimfive | {
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"Carbon dating doesn't measure the amount of carbon in an area and compare it to a set time period. Instead, it measures the decay of a radioactive isotope of carbon (radiocarbon) in organic material. Radiocarbon has a half life of 5,730 years, meaning that after 5,730 years, a piece of bone will have half as much radiocarbon as it did when the creature it belonged to died. In another 5,730 years, it will have half that amount and so on and so forth. Half-lives are a constant. An isotope will always have the same half life no mater how old it is or what it comes from. Radiocarbon raging is accurate to about 50,000 years (I think after that the amount becomes so small it's just hard to measure accurately) however it seems newer technology is getting more accurate, and scientists can usually narrow down at least a time range Radiocarbon is usually measured with an accelerator mass spectrometer these days. An AMS can separate and count all the individual radiocarbons in a sample. Before that, a Geiger counter was used to measure the decaying radiocarbons, but only picked up the ones that were decaying at the time of test. Because there can be changes in the concentration of carbon isotopes over time as you put out, scientists usually compare samples to tree rings. Each ring of a tree preserves an accurate snapshot of the amount of carbon in the atmosphere at any given year. Using the information from the tree rings, they are able to factor a calibration curve into the mathematical formula used to calculate age. The effect industrial carbon has had on diluting the amount of radiocarbon has been studied well enough to be accounted for in artifacts dating from the 1800s on. Nuclear testing also led to short periods in which organic mater absorbed more radiocarbon but because this happened over a comparatively short amount of time (1945-1965) it is again easy to account for . We'd be able to tell if something pre-dated that 50,000 year mark, but it would be tricky to figure out by how much since measurements get less specific after a certain point. However a lot of fascinating research has been done into how so-called primitive cultures use math, observation, and science to make extremely advanced leaps in technology. The ancient Greeks had automatons and even analogue computers. What looks like the result of highly advanced tech like the maps you are talking about are likely just sets of skills that we do not possess any more. People dedicated their lives to studying cartography, math and science and were able to some amazing things without the aid of electricity, satellites, or complex computers. The societies within recorded history were pretty darned advanced when you think about it.",
"Carbon dating isn't using carbon levels. There are two forms of carbon. One is slightly radioactive, and decays into the other kind over many years. Sunlight triggers the process that produces the slightly radioactive kind. Carbon dating looks at the ratio of the two kinds in the object. This tells you when the carbon in the object was last in the sunlight. If the ratio is the ratio caused by sunlight, then the carbon atoms were in the sunlight only a few decades ago. If the ratio is almost all the non-radioactive kind, then the wood the object is made of is very old because it is made of carbon atoms that have had a very long time to decay from the last time they were in sunlight. That doesn't mean the object is old, it could have been made yesterday from a thousands of years old piece of wood. It takes more archeology to put all the facts together to determine an age range."
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65dfsf | What are the black dots around car windows? | You know, the border of the windows with dots of different sizes. Why do some cars have them and some don't? | Technology | explainlikeimfive | {
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"It's just a way of blending the boarder of the windshield. There is a black boarder to attach the glass to the car, instead of having a hard line they put dots (or a fade) to blend it out."
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65dpc1 | Before GPS, how did pilots navigate planes? | Technology | explainlikeimfive | {
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"Lots of good answers here so far, although none of them are totally complete. I'll try to fill in the gaps: - The most basic way of navigating is **ded reckoning**. This involves measuring the direction you want to go on a map, as well as the distance. You calculate the amount of wind correction required. Then you point your aircraft in the right direction and start a stopwatch. At some point(s) along the way, you can visually check whether your headings and timings are working, and if not (for example if the wind isn't exactly as forecast), then you make corrections. All pilots are taught this as the basis of all other navigation during their basic training. - The next most basic system is the **NDB**. This is just a radio beacon on the ground that transmits in all directions. The receiver in the aircraft can detect which direction the NDB signal is coming from, and point towards it. When combined with a compass, the pilot can ensure he flies along a line that goes to/from the NDB on a predetermined path. It's quite difficult to use, and subject to lots of errors, for example it doesn't work very well near mountains, at night, or near thunderstorms. - After that comes the **VOR**. Unlike the NDB, it transmits a slightly different signal in every direction. The receiver in the aircraft can detect where it is in relation to the VOR by interpreting the signal it receives. It's much easier to use than an NDB, and much less prone to errors, but essentially it's used to do the same job. - NDB and VOR are usually used together with **DME**. DME is also a radio beacon on the ground. The receiver can work out the distance the aircraft is from the beacon. They are often located in the same place as an NDB or VOR. So when you combine them together, you can work out what direction you are from the beacon, *and* how far you are, which enables you to fix your position. - Air traffic control have **radar** which enables them to see your position more easily (and often more accurately) than any of these navigation aids, but obviously that only works when the controller has the workload to use it - Even air traffic controllers who don't have a radar screen often have **direction finding** equipment, which enables them to tell what direction from the airport the aircraft is. And a few air traffic controllers can use more than one piece of direction finding equipment together to \"triangulate\" the position of the aircraft. These work by simply pointing at where the pilot's radio signal is coming from. There are a few other systems that are only used very rarely, too, but this covers most of the systems that are in use today.",
"For a time, [giant concrete arrows]( URL_0 ) were part of the equation. These were used in early airmail as an additional navigational aid to the other things mentioned in this thread."
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65dyjk | Artificial intelligence | How does it work. It's like a man made brain correct? How can something so complex, and convoluted actually be accomplished. Even on a minor scale. And what could this technology progress into? Could it make the modern solider absolute? And what moral bounds do the people furthering this technology abide by, if any? | Technology | explainlikeimfive | {
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"Artificial Intelligence is not a very precise term. It can be used to refer to lots of different types of computing, from machine learning to the way that NPC's behave in video games. I can speak to what I know about, which is computer vision. In order to teach a computer to \"see\" we just think about how we \"see\". If I'm looking at a person sitting still and then they move, how do I know they moved? Because they were in one place and now they are in another, I can compare what I saw before to what I see now. So to train a computer to \"see\" movement, we capture an image, then capture another and find the parts of the images that changed. That is a simple example of creating an \"intelligent system\". There are more complex methods of \"teaching\" computers called \"machine learning\". Machine learning is a method of programming a computer by allowing it to program itself. Essentially, in computer vision, we might want a computer to identify a rare species of bird in an image. In order to \"train\" the computer we would give it 1000's of images with the bird in them, and 1000's of images without the bird in them. We tell the machine which images have the bird and which don't. The machine then performs a complex analysis of the images to determine what common characteristics exist in the images with the bird and don't exist in the images without the bird. This process can take a lot of time, but when the training is complete the computer generates a \"model\" of what an image with our bird looks like. Then when it sees new images it can apply its model to quickly \"see\" if our bird is present. This is the process used by many of the major AI projects being done in the world such as IBM's Watson. The trained models aren't always perfect and sometimes fail, it depends on how robust the training set is. Even \"man made brain\" is not a very precise term. This could mean a computer system that can play chess or identify and remove a defective product from an assembly line. Both might seem intelligent but they are only capable of doing very specific tasks. I think artificial intelligence as you imagine it is very very far away from being invented. The human brain is incredibly complex and operates in a non-digital space. Computers think in 1's and 0's, human brains use many different neurotrasmitters (30+ depending on who you ask) to pass signals around from neuron to neuron. On top of that the human brain operates more like a GPU than a CPU and has trillions of neural connections (computational cores) compared with the few thousand present in most GPUs. So, the human brain is a general purpose analog cluster \"computer\" whereas computers are digital, general-ish purpose, serial-ish computing machines. I don't know why you (and many others) suddenly jump to warfare when discussing AI, but I assume it has something to do with the long history of movies that talk about machines taking over. I don't think there is much serious concern in the scientific community regarding moral issues of machines taking over, because the types of research being done in artificial intelligence is so basic and elementary that it is an absurd notion. That isn't to say that people don't discuss the long term possibilities, especially as we become more dependent on the internet in our daily lives. I know Elon Musk has voiced concerns over the possible dangers on cognitive computers. The concept from the Matrix or Terminator movies are unrealistic views of a machine controlled world, what is more likely is machines would manipulate financial systems and communication systems making it difficult to carry out our lives as we currently do, but one would have to ask what motivation they would have in doing so? Also, humans have existed for hundreds of thousands of years without modern infrastructure, governments, and computers. If all of those things went away, lots of people would die, but humans as a species would carry on.",
"Right now, artificial intelligence has basically nothing to do with brains, human or otherwise. We can produce an AI to do a very specific task. People do research on AIs that can move a robot from one place to another without hitting anything, or AIs that play chess, etc. Those AIs are just computer programs that take a bunch of information as input and produce some output in response. Typically that output is an attempt to meet some goal, or an attempt to get closer to meeting some goal. People can take in information and learn how to do new things. People can identify something they want to do, that they have never done before, and figure out how to do it. Right now, in a general sense, no AI can do that and we have no idea how to make an AI that can do that."
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65e6kr | What's the difference/relationship between the Internet and the World Wide Web? | I was listening to a fascinating NPR segment with the inventor of the WWW, Timothy John Berners-Lee, who stressed he *did not* invent the internet. I knew they were different, but never precisely how. The segment seemed quite informative, but because I was driving through the middle of nowhere, it kept cutting out, so I couldn't quite grasp it. Any help is appreciated! | Technology | explainlikeimfive | {
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"The Internet is a global network of computers. The World Wide Web is one of many services that runs *on* that network The Web is specifically the stuff you can access through your browser: a set of documents, referencing each other by way of hyperlinks. Email (for example) was not originally a web service, but it still runs on the Internet. It is in fact a *parallel* protocol to the World Wide Web, although the advent of webmail services like GMail, which provide browser-based interfaces to email, has blurred the line somewhat. Usenet is also (these days) an Internet service. So are IRC and the Network Time Protocol. *Lots* of things can run on the Internet, and while there are now WWW-based gateways to most of them, they're not themselves part of the World Wide Web."
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65fckl | My Mac can run every pre-Wii U Nintendo game ever made. Why can't a new Nintendo console do the same? | Technology | explainlikeimfive | {
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"There are at least 3 problems * Many games that you think \"run\" on your Mac (or a Raspberry Pi) don't really run 100% as they where intended. It might be something easy to miss without a side by side test like the Triforce pieces moving too quickly at the start of Link to the Past or it could be entire elements are missing (often things like audio since they are often the most sensitive to timing errors caused by emulation). * It takes money and time to both verify that a game is emulated correctly and to *also* verify that the game doesn't run foul of modern things like age ratings (unless you want to rate them all AO) that didn't exist when they where made. * Nintendo doesn't own most of the games released for their systems. Even many games that do have Nintendo's name of them (like Super Mario RPG) are tied up with other rights holders. Indeed some games are basically impossible to work with because the rights have been split and shuffled around so much (ie one company owns the code, another owns the character IP, a third owns the original distribution rights). All of this isn't much of a problem when you pirate games and load them up with no expectations. When Nintendo does it they are taking on a large legal responsibility."
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65gzhu | Why did 'SOLAR FREAKING ROADWAYS' never come into fruition? | For something that seemed to make so much sense/generate a lot of hype, why has the idea died off? | Technology | explainlikeimfive | {
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"The people making it can't even figure out how to get a roughly 15 foot area of sidewalk panels to light up, let alone produce energy, and that's after several million dollars, and YEARS of work. The entire designed is flawed, as they are too fragile, would never be able to reach 100 capacity (solar panels need to be angled towards the sun, road needs to be flat). Plus, glass is a HORRIBLE road surface. Aside from the fragility issue, the second it rains, you'd might as well be driving on ice it's be so slippery. Oh, and it's also completely cost ineffective.",
"> why has the idea died off? Because they tested it, and [it failed miserably]( URL_0 ). Their prototype couldn't actually be driven on, had multiple hardware failures and panels that were dead on arrival, and normal rain shorted out even more of them. Solar panels are much better served being installed on top of roofs, where they're angled to drain off water, and don't need to be tough enough to withstand thousands of pounds of pressure from cars and trucks.",
"Because it was a horrid idea. Solar panels are not durable enough to be used as pavement, and they are definitely too fragile to have cars driving over them.",
"> seemed to make so much sense/generate a lot of hype It never made any sense and the only hype it generated was all the talking about how stupid the whole idea was.",
"Because to everyone's surprise, solar power doesn't work when it's blocked from the sun. Which is what would happen when it's covered in dirt, snow, rubber marks and other various crap. It was a retarded idea based on that alone not to mention a whole host of other issues.",
"You know what would also work? installing solar panels next to existing roads",
"Because it was a stupid idea in the first place. Maintenance costs alone would be astronomical. Eventually rubber from the tires would build up and the panels' efficiency would tank."
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65h6js | Why is the dark web so big? | People always say that the dark web is much much bigger than then normally accessible internet. But why is that so? Why are there so many more "dark stuff" than normal ones? | Technology | explainlikeimfive | {
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"it's because literally every website that isn't normally accessible is in the dark web. This includes someone's google drive, anyone's facebook dashboard, etc. There's a lot more private pages needed than there are public ones.",
"That's because of how the 'Dark Web' is commonly defined. In news media and articles, they usually mean intentionally hidden, illegal websites, selling weapons, drugs or similar. But these sites are, in fact, just a small part of the so-called dark web. People saying the dark web is much bigger than the normal web are right - it IS by far larger, but that does not mean \"for each normal website there are twenty sites offering illegal stuff\". It simply means that there are way more unaccessible documents online, than there are acessible ones. Let's say I write a single page of html with a steamy loveletter to my SO. I put the document into a specific folder on my webspace and install rules for search engines to not index, read, archive, link or remember the folder and its contents. You would never 'find' my letter by using normal means, like a search engine. You either would have to know the exact link yourself or stumble upon it by accident, while browsing my site and manually (!) change the url of one of my 'open' web documents. To be extra sure, I could use password protection, encryption and whathave you - until, in the end, a normal user surfing the web would never get to the letter without serious intend. My letter was also part of the dark from the start. It's nothing illegal. Just - and this is what nearly all articles mean when writing about the dark web - not able to be found by search engines or external links. Add in configuration files, script files, databases, folders with thumbnails, documents containing nothing but machine code (you get the idea) and you have a metric ton of unacessible stuff online, not found or indexed by search engines. That, too, is part of the dark web. Edit: Spelling",
"You don't mean dark web (the web accesible via Tor), you mean DEEP web. You see, the internet is divided into 3 parts: the surface web, the deep web and the dark web. The surface web is everything you can find with a search engine: menu of your favorite restaurant, movie timetable at your favorite cinema etc. The deep web is what you have mistaken for dark web. It's the largest part of the internet. It DOES NOT contain illegal stuff. It's everything you can't find with a search engine but is still accesible by a normal browser like Chrome or Firefox and usually requires the user to log in. It's usually not some top secret governmental stuff, but for example university research data or stuff like that. Heck, even your FB Messenger conversations are in the deep web. The dark web is what's only accessible via Tor, and what people think that contains all the super shady stuff. It's pretty small (one can't really count all the dark web websites since there's no search engine but those who attempted counted only about 3000) and for the most part it's just people who want to say what they think without the government standing above their shoulder (like it does in China, for example)"
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65hmci | How are the songs on the radio encoded into radio frequencies? | Technology | explainlikeimfive | {
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"text": [
"If it is analog radio there are two ways AM and FM. In both cases you have a carrier wave at the frequency you set your radio to. The carrier wave has higher frequency then the sound. The sound you can hear is < 20,000 hz and the carrier wave is in the 1,000,000 hz range AM (amplitude modulation) changes the amplitude of the carrier wave with the amplitude of the sound ie a multiplication of the signals. FM (frequency modulation) is more complex and you change the frequency of the carrier wave with the amplitude of the sound and keep the same amplitude. You can see an [animation] ( URL_0 ) on the wikipage of how it looks. And if the question is for digital radio then the answer is more advances because the song is encoded like a mp3 on a computer and then transmitted digitalt on like hos WiFi works (not the same but similar)."
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65jp1z | Part 15 of the FCC rules that requires a device to ACCEPT any interference received, including interference that may cause undesired operation. | e.g. Compliance for the above requirement is mandatory even for a [Fisher Price ABC toy for toddlers]( URL_0 ) | Technology | explainlikeimfive | {
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"Pretty much every electronic gadget emits radio waves (RF), even if not intentionally, which means they have to be certified under the FCC's Part 15 rules for unlicensed transmitters. Because Part 15 devices tend to leak RF, many are also prone to having signals around them get into their circuitry and cause problems. The must-accept rule simply says that if you have a Part 15 device that's so poorly-shielded that it does things it shouldn't in the presence of signals it didn't radiate (other Part 15 devices or transmitters licensed by the FCC for other services), that's entirely your problem. The rule is largely there to keep the FCC from getting a lot of irate phone calls. This was a much larger problem 40 years ago than it is now, as most things are shielded well enough and have circuitry to filter out interfering signals.",
"> There is a hierarchy of certifications, based on the utility of the device to the public good. > At the top is civil defence and emergency communications. Nobody can interfere with them. They can interfere with just about anyone and get away with it. > Then comes public safety, such as aeronautics comms, police and ambulance. Nobody should interfere with them, but no guarantees. Pilots occasionally note some interference from government comms, but can't do much more than switch to another frequency. > Further down the list are public broadcast stations, radio and TV. They are also serving the public good, unless you look at their bland content :-) Normal people should not be interfering with TV broadcasts, this means your power drill or computer interfering with your neighbors soap opera is a bad thing. If your neighbor complains, you must stop using your drill or switch off your computer. > At the bottom of the shitpile is consumer electronics. If a TV transmitter is interfering with your gear, tough shit. You have to accept the interference. No complaining. Your device also can not create any interference with any of the more privileged services such as airplane radios or emergency comms. > URL_0"
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65kakn | Can scratches on a DVD corrupt the files, and if so, why or how? | Trying to understand why a store bought DVD won't work at certain scenes. | Technology | explainlikeimfive | {
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"text": [
"Firstly it is important to understand how CDS and DVDs work and I will make an assumption as to where the scratches would be. Firstly CDS and DVDs are optical media, that means they use light (laser) to be read. The information on these discs is made up of lots of little tiny 'dots' a bit like morse code. Where there is a dot let's say this is a 1 and where there isn't a dot say this is a zero. And for arguments sake, a computer or anything that reads this information reads it as 0's and 1's this is known as binary and let's just assume your computer is happy with that. Now, if you look closely at a disc the side that is not printed, usually the shiny reflective side is a glass like polymer which is actually a protective surface which sits above a foil like material called a substrate, and it's this substrate that has all of the holes (the 0's and 1's) which have the information on. So, a scratch that only goes as deep as the clear polymer and doesn't touch the substrate will stop the laser seeing through the cover properly (like looking through a scratch window) but theoretically could be repaired by polishing the scratch out of the surface so the laser can get through, but if a scratch was to damage the deeper substrate the 0's and 1's would be lost. Now, as for files, these are just groups of 0's and 1's that make up something particular like say a word document or a song and if some of those 0's and 1's can no longer be read from the disk the whole file could become broken. Now there are many ways clever people have invented to make 'files' more tolerant to the loss of a 0 and 1 here and there so it doesn't always mean a total corruption. A DVD movie is a collection of files (usually chapters and scenes). So a damage to these could result in some scenes being unreadable or difficult to read. TL;DR. A scratch only to the polymer can be polished out to save data. While a scratch deep enough to damage the substrate could cause loss of data."
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65kf60 | Why is the Reddit search tool on the app so slow/fault? | Technology | explainlikeimfive | {
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"text": [
"It is indeed pretty bad. However you may also want to brush up on your search abilities too. URL_0 URL_2 URL_4 URL_1 URL_3"
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"https://www.reddit.com/r/explainlikeimfive/comments/1z7cke/eli5_why_is_reddits_search_engine_so_bad/",
"https://www.reddit.com/r/OutOfTheLoop/comments/3csymg/why_is_reddit_search_the_worst_thing_in_the_world/",
"https://www.reddit.com/r/AskReddit/comments/3zmrhp/why_does_reddit_search_functionality_suck_so_much/"
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65kvk8 | Why does the USA have thousands of nuclear weapons? | I read earlier today that the USA has 6,800 nuclear weapons. I've looked online and that figure is an estimate, but the number is certainly in the thousands. How did that come about? I mean, I suppose what I'm asking is that 1,000 warheads is enough to probably bring about the apocalypse. Why did they manufacture so many? What can you do with 5k nukes that you can't do with 500? | Technology | explainlikeimfive | {
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"The problem is that the your enemy, the Soviet Union, may suddenly invent a way to surprise you and bomb your nuclear arsenal, or shoot your missiles with giant space lasers, or something like that. Thus you build more nuclear missiles than needed, so that even if half or 80% or 90% is taken out, you still have enough to destroy the enemy. As such, MAD is maintained."
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65kwhc | Why is the UI theme of many popular computer programs/apps (MS office, Google, etc.) extremely "white"? Is it functional, or simply to look modern and cool? | It seems like many of the most popular apps have extremely white and bright interfaces, especially MS office and Google. It feels like they hurt my eyes after hours of using them, much more than if they used more grays and blues. I believe Microsoft added some minor tweaks and themes to Office 2016 after complaints about this, but they seemed to do a poor job of it. Also, I assume that white would drain phone/laptop batteries faster than dark colors. Is there any science (computer or physical) behind this, or is it simply marketing and product design? | Technology | explainlikeimfive | {
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"White does not affect battery life on most screens. Regular LCD screens are lit up 100% white in the back, and then use polarizers to darken the non-white pixels. This aesthetic originated at Xerox PARC and was then copied by both Microsoft and Apple. It is meant to make the screen look similar to a piece of office paper, since desktop computers were originally meant largely for office work.",
"High contrast ensures everything is readable. If your eyes hurt, either manually turn down the screen brightness or get something like f.lux to automatically adjust it during the day.",
"I always assumed a white background with black type is used because it resembles paper and ink and that's what most people think offers the best contrast. I must be in the minority, maybe because I have sensitive eyes, but I hate all the white space. It makes my eyes tired. I go out of my way to switch to \"dark mode\" everywhere and anywhere I can. Reading light text on a dark background if my preferred option every time. I'd even love a browser that would render pages that way for me. When I switched from Windows Phone to iPhone, the very first thing I missed was that lovely system-wide dark mode. Especially combined with the inky blanks and vibrant accent colors you get on an OLED screen. I am holding onto hope that Apple will finally introduce the system wide dark mode for iOS that people have been asking for when iOS 11 launches. iOS is a platform that seems like to have A LOT of that glaring white space, so whether or not they remedy this will definitely be a factor for me when I decided on my next smartphone and tablet.",
"It's actually due to a trend which resulted in preference toward minimalist design principles. Basically the less stuff on the screen the better. Designers learned this means that essential functionality, like a button, is more visible to the end user. So it is both functional and modern. This trend likely came about due to conflicts of previous designs, in the late 90s and early 2000s, where everything was more designed by coders than artists and essentially everything was just thrown on the page. This resulted in the end users becoming confused or lost as where to find the important features or options that they need. And just gave people a very 'cluttered' feeling. Minimalist software design itself was then pushed by 'the big dogs' like Apple, Google, and Microsoft who not only create many of the applications a typical PC user will see, but also much of the software that developers use to create their own applications. So this put it into the mainstream and it was adopted as a sort of standard."
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65l0p6 | What exactly is plastic and how did it become so wide spead? | Technology | explainlikeimfive | {
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"Plastic is composed of [polymers]( URL_0 ). Polymers are organic molecules composed of a chain of many monomers; basically an organic molecule that easily links to others of its kind to form really long strands or surfaces. Basically, carbon has 4 links and can easily link with other carbon molecules present in organic compounds, forming really long chains or large surfaces. Plastic is wide-spread because it is easy to create (chemically), because it's easy to get different plastics with different characteristics, from soft to rubbery to hard, transparent or not, etc., because it just takes a little bit of heat to be able to shape it into whatever shape you need, and because it's chemically inert. Thus, plastic is an alternative to glass (which is brittle), to metals (which can be shaped but can be rare or expensive), to wood (degrades if wet or left outside in weather), and to ceramics (also brittle). This is why it's popular."
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65l4tw | Why is it that when files are interpreted by audio software as raw audio data, strange sounds such as static and tones appear? | When using audio software such as Audacity, you can import any type of file, be it .mp3, .exe, or .dll, as raw data. The results can be pretty astonishing, especially with files such as mspaint.exe, explorer.exe, and shell32.dll where white noise and tones appear, creating sections that could be almost classified as melodies. What is the technical science behind this? Here are some examples that you can hear for yourself: URL_2 URL_1 URL_0 | Technology | explainlikeimfive | {
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"The values in computer code could basically be random, at least having no pattern that corresponds to recorded or synthesized audio. White noise basically **is** random variation over time. But you can also get repetition in code, and repetition over time is what we perceive as a consistent tone/note, a harmony of multiple tones/notes, or even a melody as they change over time or are repeated. The items that are being repeated have no relevance to instruments or \"music\", but if they're repeated in a pattern (do this thing once than that thing twice) we'll perceive that as harmony, though not necessarily a perfect one or one without noise going on as well.",
"Basically, any kind of repetition that doesn't succumb to noise is going to make a perceptible tone. That tone depends only on the length of data that is repeated. The particular contents are just going to affect timbre. Prime suspects are arrays of data structures. Those structures tend to have similar values at the same offsets and repeat at regular intervals. Code itself will generally sound like noise because nothing really repeats that much. Maybe architectures that use instructions of fixed length will produce a kind of high-pitched tone, but still with lots of noise. The first video has this in the description: > The reason it sounds this way is because there are a bunch of raw icons embedded into the executable, each one ordered from small to large. So, what you're hearing is mostly image data. That must be the part where it constantly goes from short high-pitched notes to long low-pitched ones before repeating. The repeating parts making the tone must be rows of pixels in the icons. The short high-pitched part is that way because rows are short (making a short wavelength and high pitch) and there are few of them (making it a short note) in small icons. The long low-pitched part is exactly the opposite in large icons. And this repeats with variations in timbre because there are many icons."
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65lykh | Why do people get headaches after playing video games or watching TV for too long? | Technology | explainlikeimfive | {
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"text": [
"* Dehydration from low fluid intake * Slow blink rate, causing dry eyes * Poor body posture * Hey. Hey. Hey Listen. Hey. Look. Hey. Hey. Hey. Look. Hey. Listen. Listen. Hey."
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65mf6c | How do save states work? Why are they so small compared to save ram, yet recall so much information? | Technology | explainlikeimfive | {
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"In game consoles? The amount of RAM in old consoles is absolutely tiny. The NES has 2K of RAM, 2K of video RAM, 256 bytes of OAM and 28 bytes of palette RAM. To save an arbitrary state you'd also need to store things like CPU registers which won't amount to much either. Saved games can be tiny on many games when the amount of stuff to know is just the position, HP and inventory. On some, even less."
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65o9a3 | How does my broken handsfree turn musics to instrumentals? | So today I found my earbud's wires to be broken, and after playing a few music, I realized it filters out the singer's voice from the music, my musics are all instrumentals now, wot? This seems to be more apparent among Rock/Metal musics where the bass guitar has a bigger contribution to the sound, sometimes more than the vocalist. Take "Lake of Tears - Leave a Room", I got to listen to the instrumental music without hearing the vocalist at all today, unique experience eh? :D | Technology | explainlikeimfive | {
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"There's a pretty complex thing going on. Headphones use a TRS connection - which instead of having 2 dedicated wires for each channel (2 for L/2 for R) it has 1 for L, 1 for R and 1 common ground. Due to the common ground, when things short *just* right, 1 of the 2 channels can become electrically inverted, thus any sound that is completely identical on both Left and Right channels gets canceled out by the inverse electrical signal. Most songs are mixed with mono-channel vocals directly duplicated on top of both channels equally, while the instruments are almost always recorded in stereo. Thus, with the mono vocal track being canceled out you're left with an instrumental. Some songs have stereo vocals, some have mono instruments, and some songs are recorded 'all at once' so that you hear the vocals (slightly) in the instrumental recordings. It won't work on every song but it's a pretty neat trick.",
"I had the same issue once, I'm not certain, but I think that either the left and right channels were touching, or just one channel was completely disconnected. I found an explanation of how to replicate the effect with audio editing software [here]( URL_0 ). It seems to be saying that because the vocals are often given equal volume in the left and right ears, when one channel is inverted, and the signal is set to mono, then then vocals cancel out. The instruments, however are often made slightly louder in a particular ear, and therefore can still be heard. Think of it as a maths problem: left ear = 10sin(x) + 4sin(2x) + 7sin(3x) right ear = 10sin(x) + 6sin(2x) + 6sin(3x) left - right = 10sin(x) + 4sin(2x) + 7sin(3x) - 10sin(x) - 6sin(2x) - 6sin(3x) = -2sin(2x) + sin(3x) See how the sin(x) cancelled out because it was balanced in both the left and right ears? Just to reiterate: not 100% certain, but I'm pretty sure its something along those lines. Hope this helps < 3"
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65q73k | Why is reddit's search feature so bad? Most of the time it says "search failed" and it's always slow. | Technology | explainlikeimfive | {
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"Right. And then I get down-voted when I post something in askreddit that had been previously posted but is not searchable. I got blocked from askscience for not being able to find previous questions.",
"I don't work for reddit so I don't know how they have written their algorithm, but maybe I can explain a little about search algorithms in general. (CompSci bachelors here). There are three major comoponents that go into how a search algorithm runs: how the algorithm is written, what systems the algorithm has to chug through, and how many resources are available for the algorithm to run. About how algorithms are written. There are many different ways to write a search algorithm. If I put in \"water\" as a search term for example, I could match in many ways. 1. Match on terms that begin with \"water\" (\"water is great\" would match. \"I hate water\" would not.) 2. Match on terms that end with \"water\". (the opposite result of number 1.) 3. Match on terms that have \"water\" in them. (\"I love water sometimes\" would match, and so would the two examples in 1.) As you can see, the first two methods of matching would run more quickly because terms can be eliminated much faster. But obviously it is much less accurate. The problem with the last method of searching is that the algorithm must go through almost every piece of data to find matches. About the systems used in an algorithm. I have no idea what reddit uses specifically, but I will give an example of how something could be built. There are many layers to a website: front end, back end, and the database. The front end is things like javascript amd html, which format the page the user sees, and the results of a search must be loaded into. The back end is where the server doing computations lives, and this is where the server takes the user's search query and decides what to do with it. Usually, the backend will translate a simple search like \"water\" into something that the database can understand, and then asks the database for the info. Then the database receives the request for data, chugs along the query and looks for the results. Then the database sends the results back up the chain, eventually getting to the user. As you can see, even something as easy as \"water\" goes through multiple layers. The problem here is not necessarily how many components there are to the system, but rather the time it takes for one layer to talk to the next. The system usually has a built in timeout if a query takes too long, because nobody wants their server held up on a query for ages. It is possible reddit's timeout is 30 seconds for example, when the query actually needs 1 minute to run to completion. Finally, the resources available for a query. This is not so much about the server's resources, but the database's. If the database does not have a lot of processing power, it will take a little longer to run, especially if the database has A LOT of data to go through. Some database systems are better designed for big data than others. It is possible reddit has chosen one type of database system that isn't suited for querying large amounts of data in a reasonable amount of time. But now they are \"stuck\" with the system because trying to move mountains of data to a new system would be tons of effort. Sorry this was so long! Hope it helps.",
"It's easier to add reddit to a Google search for something you want from this site. Their search has always been garbage and the only changes they make to it always seem for the worse.",
"Reddit is not built or managed by particularly smart people. They do not invest many resources in search because it isn't much of a benefit to them. Making Reddit popular and finding a way to make it profitable is far more important.",
"> Why is reddit's search feature so bad? Poor/rudimentary search algorithm. I'm not sure if it's open source, but you can tell that it tends to look for literal matches. It gets easily confused by partial terms. Search engines like google are high optimized to use things far beyond the literal words to rate how likely something is close enough to what you wanted > Most of the time it says \"search failed\" and it's always slow. This is a resource thing. They intentionally put the search on low priority. Reddit seems to run pretty close to the line on server power/capacity, and search is the first thing to die when things get busy. It makes sense, from a limited resource perspective- you want the main site to work well, search is \"less important\" most of the time. Speed is a mix of both of those things- lack of resources to crank through stuff, and inefficient algorithms to sort through junk.",
"A lot of people here are talking about algorithms and resources and code, but that's not the real underlying cause for Reddit's search sucking. I'm a web developer, the fact is, site search is a solved problem. There are countless search libraries and services they could use, and they have all the talented engineering resources they could ever need to do it. There's no technical excuse for it being so bad. The legit reason is because Reddit management has decide poor search is a feature and not a bug. They've decided that bad search functions indirectly spur new site activity. People post new things rather than simply digging up old threads. There are even full communities dedicated to fulfilling a search like function. In addition to this, there's no reason to believe that better site search will yield increased traffic, so it's probably difficult to justify expending resources on it anyway. Trust me, engineering issues are not causing a site of this scale to have bad search.",
"All these explanations are focusing on the technical aspects which is great, but the truth is Reddit's search is terrible because: There is no monetary incentive for Reddit to provide a better search. If there was an incentive to provide better search, Reddit would hire the people to make it happen (implementing a semi-decent search is not outrageously difficult today as it was 20 years ago).",
"Because they know we just use Google, and their profit margins are so narrow they're probably strangling on them.",
"Doesn't answer your question but if I'm on mobile then I'll Google my Reddit search and typically find what I'm looking for. The same key words on Reddit bring up zero results.",
"I find a song on Spotify on my discover weekly playlist that was good so I looked at the artist page and noticed the song was at < 1000 plays so I pulled up /r/listentothis and searched just the artist name it said no results. So I posted it and got redirected to the existing post that was still on the front page of the sub",
"So, everybody seems to be ignoring the search failed part. That part is a bit more recent than search being generally useless. The constant \"searched failed\" is a [known issue]( URL_0 ). We don't really know what's causing it, though.",
"It's funny, this was an issue years ago. I remember everyone complained about search on Reddit (the website). They ended up using a different company to integrate their search results and it worked really well for a while. Not sure what happened because now it's terrible again, at least on mobile."
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