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ez4lk2 | How do PC games identify pirated copies but some pirates bypass that? | Technology | explainlikeimfive | {
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"You’re referring to DRM or Digital Rights Management. To understand how it works, you need to know a little bit about the history and the history goes back to the 1970’s! In the early days of arcade machines most of the arcade cabinets contained a system ROM (Read only memory) chip that stored the game code, but a secondary chip that verified the authenticity of the ROM. This way, even if pirates wanted to make knockoff arcade machines, copying the ROM chip wasn’t going to be enough. Eventually hardware hackers found ways for the various machines to bypass the authenticity check entirely. Later games for PC platforms usually had some kind of user DRM. It might be a code in the manual, it might be a dark sheet of paper that wasn’t easy to photocopy, in the case of one game console, there was a literal crystal that had to be held up to to the TV set to decode a pattern. Later games used codes that were in the manual as a sort of “license key”. That was a bad idea because pirates could just include the key in a README file. In the console era, many games were encrypted or used physical copy deterrents. Sony made disks that had a slight “wobble” that would make copying the data from them nearly impossible. Modern Vintage Gamer on YouTube has a series that covers the methods used by different console manufacturers and it’s definitely worth a watch. The other method that is slightly more modern is a checksum that verifies the integrity of the game code. If the checksum fails, then it’s apparent that it’s a pirated copy. Look up the G-Mod anti-piracy scheme for more on that. Very fascinating. Today the most common copy protection is the (very controversial) “always online” method. That’s where when you start up your game, it verifies itself with a certificate that certifies the copy of the game as legitimate. If it’s not legitimate, the game generally won’t start or the developer will have implemented some features to troll the pirates. (Check our Serious Sam) Disclaimer: I’m a little drunk at the moment, but I’m happy to answer any questions you might have tomorrow when I’ve sobered up a bit. I’ll probably also make this comment a bit more detailed.",
"Well, to make a complex and lengthy explanation short. Game devs give each single copy of game a unique piece of information, which is then verified against the information that is in their servers. If all is good, the game is legit. If not, it gets detected as a false copy and cannot be played. If it couldn't communicate with the official servers, the game automatically blocks itself from running. Pirates perform complicated tampering of the game software to bypass this; this includes blocking the game from ever communicating with the official servers, and making the game itself think it is legit by injecting it with a false information. Tldr; pirate groups tamper with the game with their amazing software engineering skills so it won't get detected as pirated"
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ez5t8a | Where do files go when they are deleted from a computer? | Technology | explainlikeimfive | {
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"They just flag the space which the deleted file occupied as empty. The next time a file is created it occupies that space (or portion of that space) and overwrites the data. That’s why deleted file recovery software works, the data is still there.",
"The index of the drive is adjusted to indicate that the space the files were using is now available to be used by different files. The data isn't actually moved. & #x200B; Mechanical hard drives use an arm that physically moves over a platter sort of like a jukebox to access different portions of a disc, whereas a solid state drive has no moving parts and can access the data faster."
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ez742b | The business model of Putlocker/123Movies who constantly upload new content. | Technology | explainlikeimfive | {
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"These sites probably don't have legal costs, because they put their servers in places that don't listen to piracy lawsuits from outside. Also, even if they do get a strike, all that can be done is that the domain gets taken down, and then they simply rehost on a new domain. And the ad revenue is probably much higher than it seems, because of the sheer volume of ads that they show to each user. You don't need a huge user base to become profitable if each visitor is being shown 10-20 adverts per thing they watch (which of course means 10-20 adverts every 30 minutes when watching a TV series). But then they end up having a huge user base anyway. Also, I suspect it's not really intended to work as a *business*, especially not for the more niche sites, like the website where you can only watch American Dad or the website where you can only watch Attack on Titan. A lot of these sites are just good samaritans who either want to share a series they like or who want to do something about all the industry bullshit. Like how the people who crack video games are doing it for fun and because they believe in piracy, not because they particularly want to make money. So, a lot of these sites don't necessarily need to be profitable, they just need to recuperate enough money that the creator can keep hosting the content.",
"I'm no expert here but those websites are full of ads, usually along the lines of hot housewives in your area looking for you (what luck!). I would imagine they make a decent amount since they spam you with them. Other than that I'm not sure. Maybe they also get donations or are supported by larger companies."
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ezbbhj | Why does video quality go down when copied multiple times? It’s a copy, so shouldn’t it be the exact same? | Technology | explainlikeimfive | {
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"If the source file is copied, then you won't see any video degradation. However, what usually happens is that a video is uploaded and then compressed by the video hosting site. The downloaded video is then re-uploaded and _re-compressed_ by the video hosting site again, and the process repeats every time it is uploaded. Every time a video is compressed, it loses a little bit of information. Do this enough times and the quality seriously degrades.",
"So there's that guy on yt who uploaded and downloaded and reuploaded the same file 1000 times back in the 2010s, and a few weeks ago, anoter high end channel redid the thing. Basically, when you upload a file, to make it easier to broadcast, it will be scanned frame by frame to find differences, which will be run through a compression algorithm. If there is no movement, like in a room with a wall behind, the compiler will not even bother to assign extra bits from the total bitrate to the non-moving things, just copying that part of the frame as much as possible. Basically, the more you uploaded the same file, the more will the computer try to even pixels put and reduce video complexity to save spacr and load on the server."
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ezdoyk | How does an electronic device know the time when you recharge it after weeks or months while not reconnecting it to the internet? | Technology | explainlikeimfive | {
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"Every modern computer device has a special \"clock battery\" on it. These batteries literally just keep the little bit of RAM that runs the clock going, so it can keep accurate time. In some cases, that battery is used for something other than keeping time. For instance, old Game Boy games with battery backup save files (the first generation Pokemon games is a prime example). These batteries can last upwards of 15 years without needing to be replaced."
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ezeyh0 | How does surplus electricity from someone's solar panels get put back into the main power grid? | If someone has solar panels or some other type of power-generating system at their house, you always hear that they can sell electricity back to the power company if they are producing more than they are using. Physically, how does this work? Can electricity travel 2 directions on the same wire/cable? Does it just join into the main "stream" like having a garden hose from your house flowing into a river? | Technology | explainlikeimfive | {
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"Electricity can travel in both directions across the same wire. But its limited to one way at a time. What happens is when you are generating power from solar, it first checks what is needed to supply your home. Then the excess goes back to the grid. If the panels are not producing enough then the grid supplements the rest. So electricity is only traveling either from the grid or to the grid. Not both at the same time.",
"I interned with a residential/commercial solar company while earning my Mech. Eng degree. When solar is installed on a house (or commercial property) a second meter is installed. ALL of the power generated by your panels is put into the grid. When the power company comes out they read both meters. Charge you for what your house used and give you a credit for what you put in. I never saw a case of someone having the space and money to offset their bill completely. It's more like a water reservoir. Your house used 1,000 gallons last month. You added 200 gallons. We're charging you for 800 gallons. Solar panels are DC so it goes through an converter to become AC before going through your second meter and being added to the grid."
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ezez52 | Why doesn’t Apple Face ID work when your phone is in landscape mode? Would this be possible? | Technology | explainlikeimfive | {
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"There's nothing stopping it from working. However, it's a matter of training. The AI system Face ID works on was trained using thousands and thousands of photos of faces (likely vertical ones taken with an iphone's front camera, as that's how most people would hold it). Then, that training is installed on your phone. Using that training, the AI creates a vector of your face - basically a passcode generated by measuring different features of your face. Every time you sign into your phone, it re-calculates that vector, compares it to your profile, and if its close enough, it lets you in. The problem is the difference between how humans see and how AI sees through cameras. Rotating the image is meaningless to us; we understand that objects can rotate, so we can recognize most anything in any orientation. Computers are not like that, and if you turn an object upside down or sideways, it will register as something entirely different. Throw in the different aspect ratio of the resulting image (horizontal rather than vertical), and even the same face will result in a wildly different vector. It may work if you input your face as an approved user more than once, one time per phone orientation, but it may not depending on how extensive the training data was; it might not even recognize your sideways face as a face."
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ezfx1e | Why do Android Rom's need to be customized for the phone they run on but Windows and Linux run on basically every computer. | Custom Android Rom's run only on the hardware the are developed for, but desktop and server operating systems like Windows and Linux run on basically every x86 or x64 based computer, why. | Technology | explainlikeimfive | {
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"Each phone has different hardware. It would be a different version of the processor, different wifi/bluetooth chips, different cell modems, or any number of other components. The Windows NT kernel and the vanilla Linux kernel both have firmware/drivers for a wide range of hardware built in, letting them support most consumer machines out of the box. The kernel used by android, however, has had most firmware and drivers cut out in order to make it more lightweight, leaving only the firmware and drivers for that specific model of phone.",
"Phones aren't like a PC. PCs are very standardized these days, and even though they are made of different components it's agreed on how those components present themselves. PC architecture has ways a kernel can use to ask the system \"What devices are there, and where they are, and how does all this fit together?\" So an OS when booting can easily detect things like \"Oh, this computer has an X570 chip on the motherboard, so I'll load the X570 driver\". Plus a whole bunch of equipment is just standard these days, and everything talks AHCI, so there's little trouble with talking to storage. ARM has historically had no convenient facilities to ask a device \"What are you made of, and what is plugged in where?\", so you have to build a specific kernel for the board that has already been preconfigured with the right details for the particular device."
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ezi4g6 | How do governments run mass surveillance? | Technology | explainlikeimfive | {
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"if you really want to know, go you youtube \"Government Surveillance: Last Week Tonight with John Oliver (HBO)\" tl;dr: Government can request anything from social media companies and any companies.",
"One of the ways that the NSA does it in the US is by intercepting internet traffic. These days even voice phone calls generally use the internet, so they can capture not only \"regular\" internet traffic but also phone calls. They've built at least one (and probably more than one) massive data centers to hold and filter through all of that traffic. I'm sure that a lot of it gets discarded since it is a huge volume of information every day, and a lot of it is useless/redundant. I don't know if they've set up similar data centers outside of the US to capture internet traffic from the rest of the world, but I'd be surprised if they haven't. And it's also reasonably likely that other countries do the same thing.",
"They don’t. At least not in the sense most people think; that you’re being watched constantly. What they run is mass recordkeeping. Imagine the amount of manpower it would take to surveil and analyze the behavior and actions of 300 million Americans? It’s an alright incomprehensible undertaking and definitely not one the few tens of thousands of employees working for the DOD that would have access to that information would be able to do. Instead, the problem comes with their ability to access information through secret FISA courts at whim, and the gathering of meta data/call logs over a long period of time. It’s still scary, because you shouldn’t have all that information logged without your consent, but it’s not the same as people listening in on you, which seems to be what most people believe is happening."
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ezkmuw | What exactly happens when you 'overclock' a computer? | Technology | explainlikeimfive | {
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"Operations in computers run on a clock signal. In a similar way to how a mechanical clock will have some oscillating element (pendulum or balance) and on every swing of that element the mechanism advances one step. The same thing applies to computers. The faster that clock rate the faster the operations will complete. Usually computer parts are designed to run at a certain clock speed that is decided on running stable and hitting a certain power target (higher clock leads to higher power consumption and heat). Overclocking means you simply increase the clock speed. Usually a multiplier that is referenced to a crystal oscillator.",
"You're simply speeding up the clock signal your computer and motherboard runs on. Some CPUs can do it.. some might not like it becoming unstable or just crashing your PC like running too fast and tripping over. You avoid these \"trips\" by running your computer at the rate it was tested for and advertised as on the box by the manufacturer, but some do specify a \"Max\" where tests have shown the CPU remains stable for a little extra strength. Even two CPUs of the same model, make and year may have wildly different results in overclocking, often called the \"Silicon Lottery\" by people online. What's important to Intel and AMD is that they function at the advertised normal clock rate. Running at a higher clock rate may also require a higher voltage than what's written on the specification sheet to power the few extra cycles per second you've asked it to do. Typically you want to aim for the lowest voltage increase possible while still maintaining this new performance demand so that you don't get too much more heat (Or a worse lifespan of the CPU) The final most important bit is, by doing this you'll also induce a lot more heat than usual. It's important to have a good cooling setup on your CPU before asking it to do more work or it'll just overheat and *intentionally slow down to cool itself*, ruining the whole point of running quicker to begin with. Most motherboards take care of the difficult parts for you these days. Some will even try various things intentionally crashing real quick and writing down the results until they find your perfect overclocked tuning. Or just letting you hit + or - on the base clock & voltage number fields for people who know what they're aiming for. E: [A fun example]( URL_0 ) of the Pentium 4, released in November 2000, 20 years ago... with the correct circumstances of adequate cooling and correct voltage regulation levels you can get this `Pentium 4` CPU which is rated with a max rate of 3.8 GHz, to reach 5.0GHz. Which is very cheeky and quite impressive if not funny. Only today do we have cores like the Intel i9 advertising 5GHz max clock WITHOUT overclocking."
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ezkzap | Why do car batteries seemingly die so quickly? | Why do car batteries (as large as they are) drain so fast from something as small as leaving a dome light on, when a significantly smaller battery in something like a laptop can last for hours? | Technology | explainlikeimfive | {
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"These are batteries with different technologies. That said, auto batteries do not get totally drained from a little light being on, unless for very long time.",
"* Car batteries are optimized to produce a large amount of current all at once which is needed to power the starter motor for a car. * They aren't great at maintaining a charge for a long time. * Normally that's fine because your car re-charges the car battery while you drive it. * Laptop batteries, on the other hand, don't really need to produce a lot of current all at once, but rather they need to provide a smaller amount of a current but for a much longer time before needing to be recharged.",
"The other point that seems to have been missed is how much power the dome light is using. Old dome lights were incandescent, while new ones are LED, and use about 80% less power. Much harder to kill the battery on a new car by leading a light on, because of this."
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ezltcl | why does AM radio sound so much worse than FM radio? | Technology | explainlikeimfive | {
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"Copied from elsewhere. “FM radio works the same way that AM radio works. The difference is in how the carrier wave is modulated, or altered. With AM radio, the amplitude, or overall strength, of the signal is varied to incorporate the sound information. With FM, the frequency (the number of times each second that the current changes direction) of the carrier signal is varied. FM signals have a great advantage over AM signals. Both signals are susceptible to slight changes in amplitude. With an AM broadcast, these changes result in static. With an FM broadcast, slight changes in amplitude don't matter -- since the audio signal is conveyed through changes in frequency, the FM receiver can just ignore changes in amplitude. The result: no static at all.”",
"Amplitude modulated radio (AM) changes the amplitude, or the size of the radio wave. Radio signals in general are subject to slight changes in amplitude from interference, but since AM radio is modulated by amplitude, you hear these changes as static. FM radio (frequency modulated) gets around this by changing the frequency, or how often the waves come."
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ezlx93 | How are elections with voting machines and mail-in ballots validated for accuracy? | I refuse to believe that there isn't a way to validate these elections outside of exit polling, so I would love an explanation. | Technology | explainlikeimfive | {
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"What do you consider validated? It seems like nothing could be validated, other than the removal of anonymity."
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ezmaty | Why do companies and the government still use fax machines in 2020? | Technology | explainlikeimfive | {
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"The biggest reason is legal. A faxed copy of a signature or original form is considered good to go and legit just like you had a real copy and signature. An emailed copy isn't always considered this. Many legal documents even specifically call out that faxed or original copy is fine, but disallow email. The other reason is another legal one-- if you're required to give another person a document (again like one above) a fax will show up 100% of the time and be confirmed and received by the other side. An email may get sent to a dead email box, or one thats not monitored or anything. Faxes are basically guaranteed to be delivered and received. However-- even as this above is all true, many new legal documents and organizations are finding ways to use email like a fax instead. Its going slower than you'd think. tl;dr: Its basically becauce a fax copy is guaranteed to be received and its treated like its an original copy, an email is too unreliable in a legal sense.",
"Fax communications are more secure but not 100% immune to hacking. Additionally in some states a fax document is a legal reproduction of the original. Lastly some companies/industries have just not advanced technically."
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ezn0gg | is there such thing as hack warrants or something similar? That security agencies can get from courts and legally hack into some target's computer? | Technology | explainlikeimfive | {
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"In the US, Law Enforcement agencies can get warrants for a variety of surveillance or actions. This may include forms of electronic surveillance, including hacking and monitoring internet, key logging, search records, phone records, bugging a room, or whatever they want that a judge approves. So yes, under monitored, approved conditions, a law enforcement agency could monitor or hack."
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ezocfs | Why do appliance's volumes (eg. TV, radio) use an arbitrary 1 to X value instead of basing the value on decibels? | Technology | explainlikeimfive | {
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"High-end stereos for audiophiles, or studio monitors, typically do use decibels. The problem with decibels is that either you'd have relative loudness - where 0 is the maximum and anything softer is a negative number - or you'd have absolute loudness, in which case headphones would only go up to some small number and your stereo would go up to some other number. It'd be confusing for most people either way.",
"If you run your signal through different amplifiers and speakers, the db markings become meaningless. The arbitrary numbers make more sense. Plus db isn't a linear thing relative to how you hear and experience loudness and the controls themselves are non linear. So to accurately mark off db levels might result in unevenly spaced markings.",
"Because dB measure relative loudness and work on a logarithmic scale. Try getting your average consumer to understand what that is and how it works. It's time consuming and completely unnecessary for setting a desired volume on a TV or radio. It's much simpler and easier to use for consumers to just have linear number going from 0 or 1 to whatever."
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eztfv8 | Why isn't the black box data on airplanes automatically uploaded to cloud storage somewhere? | Technology | explainlikeimfive | {
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"In the aftermath of MH370, experts say it might be time to update methods of collecting flight data. Passengers are able to text, stream and surf the internet but the data recorders on board are not communicating in real time with the rest of the world. However, the bandwidth needed to stream huge amounts of data from large aircraft is not currently feasible. Aviation author Stephen Trimble writes in the Guardian that Boeing has applied for a patent on a system that will transmit a subset of data including the plane's location: This is an excerpt from URL_0",
"Whenever this subject comes up, the difficulty and expense are always listed. Apparently its \"all or nothing\". The fact that there is NOT a GPS ping recorded just once a minute is ludicrous. Especially for planes that cross oceans. If it crashes on land, you can see the wreck. In the ocean, there might actually be a few survivors floating...if you simply knew where to start looking. We can come up with a \"best\" system later, but GPS right now is not asking too much.",
"Well, I think it records hundreds or thousands of readings per second. Plus the bandwidth via satellite isn't that great. Plus we have over 10 MILLION commercial flights per year in the United States, and none of them crash. I think the last hull loss crash of a passenger jet was in 2009, if I'm remembering correctly.",
"Pilot here (private pilot- I fly little planes for fun) There are a few problems with this. The first is cost. You know the satellite Internet modem you can buy and install on your RV for $2,500 so you get internet while you're bumming around the country? Make that an *aviation* Internet modem, and suddenly it costs $250,000-$2.5 million. The certification that anything aviation related goes through is insane, and it drives up the cost 10x or more. Fitting these gadgets on all airliners is going to cost a lot of money, and someone's gonna have to pay for it. Nobody will volunteer to pay for it. Second is bandwidth. To transmit all this data in real time would take a lot of bandwidth, which becomes a problem when you consider that there's millions of flights every day. Third is privacy. Pilots will NOT want a live stream of their every cockpit conversation going somewhere that's easily retrieved and listened to and stored forever. Pilots have no problems with black boxes, but there is concern about airlines spying on their employees, or having their conversations subpoena'd. That's why cockpit voice recorders only store 10-20 hours of audio, and there's an 'Erase CVR' button in the cockpit to erase the cockpit voice recorder. In general that button only works with the plane on the ground and the parking brake engaged, but it's there because pilots were concerned the cockpit voice recorder would be used to spy on them. Pilots would be 100% against a constant audio feed from the cockpit, and I don't blame them- chances are that audio would be stored forever on some cloud server, and what happens when 3 years from now Joe Pilot is getting divorced and his soon to be ex wife subpoena's every private conversation he's ever had with a first officer? Nobody wants that. THAT ALL SAID, there are benefits to some limited data collection from commercial flights. A system that uploads a limited set of data every minute or so- things like altitude, airspeed, engine status, location, etc. wouldn't be a huge burden. The report would be about the size of 3 or 4 text messages, so it wouldn't cause any real bandwidth problems. Things like audio data or realtime data wouldn't be part of that. In a case like MH370 it would have been helpful- MH370 did have an engine computer that auto reported, but it wasn't getting location info, so that wasn't part of the report. If the plane started in any sort of distress, this could be increased in frequency or more data uploaded.",
"Because the money required to implement that kind of a system would likely save more lives if spent somewhere else. We'd certainly like to know more about how crashes like MH370 happened, but knowing won't bring those people back, and while it *might* uncover design flaws that *could* save lives in the future, chances are we'd just learn it was human error, or in that particular case, intentional. Investing that money in better training, more pilots to reduce fatigue, and better equipment is more likely to prevent crashes than spending billions to get one black box that otherwise would have been lost.",
"Considering the makers of the engines track their units in real time yes I think it's time to update the system. It is absolutely possible.",
"The problem today isn’t whether this is possible, it’s whether it’s affordable and who is going to pay for it. Peoples expectations about the ease and cost of data streaming are based on their experience with terrestrial use in populated areas, within cell tower coverage area. Data transfer OUTSIDE that coverage is MUCH pricier and far more limited than people assume Once the SpaceX Starlink constellation is built out, routine streaming of aircraft ‘black box’ data will probably become routine",
"The FAA requires 88 parameters to be stored in the flight data recorder of any commercial aircraft. They are: > (1) Time; (2) Pressure altitude; (3) Indicated airspeed; (4) Heading--primary flight crew reference (if selectable, record discrete, true or magnetic); (5) Normal acceleration (Vertical); (6) Pitch attitude; (7) Roll attitude; (8) Manual radio transmitter keying, or CVR/DFDR synchronization reference; (9) Thrust/power of each engine--primary flight crew reference; (10) Autopilot engagement status; (11) Longitudinal acceleration; (12) Pitch control input; (13) Lateral control input; (14) Rudder pedal input; (15) Primary pitch control surface position; (16) Primary lateral control surface position; (17) Primary yaw control surface position; (18) Lateral acceleration; (19) Pitch trim surface position (20) Trailing edge flap or cockpit flap control selection (21) Leading edge flap or cockpit flap control selection (22) Each Thrust reverser position (or equivalent for propeller airplane); (23) Ground spoiler position or speed brake selection (24) Outside or total air temperature; (25) Automatic Flight Control System (AFCS) modes and engagement status, including autothrottle; (26) Radio altitude; (27) Localizer deviation, MLS Azimuth; (28) Glideslope deviation, MLS Elevation; (29) Marker beacon passage; (30) Master warning; (31) Air/ground sensor (primary airplane system reference nose or main gear); (32) Angle of attack ; (33) Hydraulic pressure low (each system); (34) Ground speed ; (35) Ground proximity warning system; (36) Landing gear position or landing gear cockpit control selection; (37) Drift angle (38) Wind speed and direction ; (39) Latitude and longitude (40) Stick shaker/pusher (41) Windshear (42) Throttle/power lever position; (43) Additional engine parameters (44) Traffic alert and collision avoidance system; (45) DME 1 and 2 distances; (46) Nav 1 and 2 selected frequency; (47) Selected barometric setting (48) Selected altitude ; (49) Selected speed (50) Selected mach (51) Selected vertical speed (52) Selected heading (53) Selected flight path (54) Selected decision height (55) EFIS display format; (56) Multi-function/engine/alerts display format; (57) Thrust command (58) Thrust target (59) Fuel quantity in CG trim tank (60) Primary Navigation System Reference; (61) Icing (62) Engine warning each engine vibration (63) Engine warning each engine over temp. (64) Engine warning each engine oil pressure low (65) Engine warning each engine over speed (66) Yaw trim surface position; (67) Roll trim surface position; (68) Brake pressure (selected system); (69) Brake pedal application (left and right); (70) Yaw of sideslip angle; (71) Engine bleed valve position (72) De-icing or anti-icing system selection (73) Computed center of gravity (74) AC electrical bus status; (75) DC electrical bus status; (76) APU bleed valve position (77) Hydraulic pressure (each system); (78) Loss of cabin pressure; (79) Computer failure; (80) Heads-up display (81) Para-visual display (82) Cockpit trim control input position-pitch; (83) Cockpit trim control input position--roll; (84) Cockpit trim control input position--yaw; (85) Trailing edge flap and cockpit flap control position; (86) Leading edge flap and cockpit flap control position; (87) Ground spoiler position and speed brake selection; and (88) All cockpit flight control input forces (control wheel, control column, rudder pedal) That is what's required to be stored, although many newer airplanes store far, far more parameters than this. The sensors are queried and the data is stored a minimum of 4 times per second, so we're talking lots of data. For instance, the Boeing 787 Dreamliner stores somewhere around a half terabyte of data (it's recording around 700 parameters, each 4 times per second, although the actual number of parameters and what they are is highly confidential and not publicly released) during a typical 6 hour flight. Multiply that by thousands or tens of thousands of flights per day and you'll being to see the problem with broadcasting the data back to the cloud. Satellite communications would quickly be overwhelmed. A flight data recorder writes the data in a loop, and typical models have ~25 hours of storage. Cockpit voice recorders don't have quite as much storage, with they typical capacity being about 2 hours. Edited to add: The Dreamliner in this example, if it's storing a half terabyte of data in a six hour flight, would require almost a 200mbit/second connection to dump all that data. That's 500,000,000,000 bytes times 8 bits/byte divided by 6 hours times 3600 seconds/hour, which equals 185,185,185.185mbit/second.",
"With Starlink and other low-orbit satellite based Internet providers imminent, this may become a possibility. Until then it's too much data for the current satellites that provide Internet.",
"Because critical management portions of airline and aircraft systems still use ancient programming languages like COBOL and send data over the Internet in the clear... the industry is not quick to make technological changes that don’t improve their bottom line."
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ezz0t4 | What is technical the difference between a thread and an async-operation? | I assume that two threads are working on a single cpu like this: | Thread1 | Thread2 | |---------|---------| | a1 | b1 | | a2 | b2 | | a3 | b3 | And are batched like this on the CPU a1-b1-a2-b2-a3-b3 | Technology | explainlikeimfive | {
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"A thread is when you ask the operating system to start running another part of the program at the same time. If there are more parts running than CPU cores, the operating system will switch between them. Threads have a bunch of features (like separate stacks) that make them relatively \"expensive\". A program shouldn't have thousands of threads because it will waste memory and time. \"Async tasks\" depend on the programming language, but they're generally things you can do in the background that are too short to be their own thread. The program will create one thread (or a few) and then that thread (or those threads) will do async tasks whenever they are ready to be done. This means a new thread doesn't need to be created for every task. \"Async tasks\" can also be things that don't use a thread at all, as long as the program can remember it's waiting for something to happen. For example, waiting for the user to type something could be an async task. The program won't use a thread to wait for the user to type something (because that's a waste of a thread) but it knows that when the user does type something, the task should be marked as completed. \"Async tasks\" got a big boost in popularity some time ago because: people wanted to do more things asynchronously (in the background), people realised that having a thread for every single thing is not efficient, and because JavaScript basically forces you to use them so people got used to them."
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ezzj06 | what physically determines the speed of a processor? | Technology | explainlikeimfive | {
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"Good question :-) Processors are large collection of transistors coupled together by small metal (copper? gold? aluminium? magnesium?) paths in new and ingenious ways, as such we need to understand how their physical behaviour: A transistor works by saturating a part of it with enough electrons or removing enough electrons from that part so that the other part of the transistor will start or stop conducting. This takes time, but the smaller the transistor the faster it goes. But the smaller the transistor is, the more weird quantum related issues show up. The paths which connect everything are laying next to each other or crisscross over each other and the magnetic fields generated by these paths can interfere with the other paths. The smaller you make the distance between the paths, the more interference. So you need enough space there. The clock signal on which the processor works needs to be everywhere more or less at the same time, otherwise it could be that your transistor logic is getting confused and 1 + 2 ends up as 4. The faster the clock signal, the less time you have to get it all in the right state, so overclocking is not guaranteed to be a working scenario. The smaller the transistors are, the less they are able to deal with heat. For a faster clock speed, more heat is produced. The lower the working voltage, less heat is produced. But the lower the voltage, the less tolerant the transistors becomes to interference.",
"To add on to what others have said: the speed of the clock determines how frequently the transistors on the CPU will switch. Switching takes some power to do. Also, a big limiting factor to how fast you can clock your CPU is actually not limited by the transistors. It's the wires going from one place to another. A longer wire will be slower to carry electricity than a shorter wire. Transistors need some time to charge to turn on and off. More voltage will do this quicker, longer wires will slow this down. The transistors themselves can actually switch WAYYYY faster than a few GHz like you see in your typical processor. For example, a smaller part of your processor, like a divider, multiplier, or a more complex function, may be clocking in the realm of 30-40 GHz. And that's not all. A CMOS ring oscillator can have transistors switching at a rate of over 200 GHz! When you combine these one after another, you will need to give some time for the signals to hop from one transistor to the next. And that's where you start making larger and larger building blocks for your processor, and those building blocks will each need some time for the signal to come in, go through, and leave. I could go on all day, but that's a very rough explanation."
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f001h2 | How does a network card make a port (for example port 80 for http)? | I don't understand how a network card or even the software on a network card can make a virtual port and then make sure that traffic is processed alongside every other port. What are these ports actually and how do they work. literally not the same repeated stuff I find on every website when I search "what is a port" i'm looking for a much more in depth understanding. | Technology | explainlikeimfive | {
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"Ports are a part of the TCP/IP protocol, and as such are part of the wrapper around a packet of data. When a connection is open through a network interface, the client and host both assign a port for communication. An automated server will have a designated port open with a program listening for TCP/IP requests for that come in; this delegates them to other open ports for the data transfer back and forth between client and server. This is integral for the multiplexing feature of TCP/IP as it allows the software to keep track of multiple concurrent sessions. By convention, many ports are reserved for servers to listen for certain types of requests, and they stay open by quickly shuffling the incoming connections to new ports. Physically they're the same as any other 1 or 0 being sent over the wire: an electrical high or low to signal on or off in a transistor. But it's in a specific spot in the data packet so that we know to expect it and what to use it for."
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f05r66 | Why is Microsoft Word a multi-GB install, yet Word Online loads in ~5 seconds with 99% of the features? | Technology | explainlikeimfive | {
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"Because the online version is mostly running on Microsoft's server, not your computer. You're just interacting with another computer (a much more robust server than what you likely have) through mouse, keyboard, and video signals going back and forth over the network. It's the same concept as not having to have Google's whole database in your PC, you just send Google's server the words you want to search for and it sends you back the results.",
"It's like reading Reddit offline vs. online. To make you able to read the whole Reddit offline we need to download tons of data. However, reading it online is much easier because only retrieving the page that is requested is much more light-weight. So when you're using Online version of a software, you're actually continuously downloading features you demanded. During the first five seconds, probably only fundamental tools are retrieved and processed by your browser.",
"Ok, I've used word online and it doesn't have 99% of the features, it's kinda annoying and i can't really stand it. Anyway, Microsoft has computers called servers that have word installed. The server tells your web browser what's running on word so it can display it."
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f06oon | How are audio and video stored on CDs and tapes? | Technology | explainlikeimfive | {
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"text": [
"On CDs and DVDs there are little bumps (burns) in the reflective surface in a spiral shape. When the laser from a disc reader \"reads\" the disk, it's capturing either a reflection (0) or a hole (1) which is binary for the machine reading it. The computer then converts the binary to a digital signal. On tapes, magnetic tape is passed through a series of magnets which record whatever you want onto the tape. When you put it through another magnetic reader, the change in fields on magnetic tape are converted to an analog signal. Edit: analog",
"Audio is the most straightforward to explain: The microphone picks up sound in waves which can be \"described\" digitally. The computer or recording device takes in the sound wave and produces a corresponding output of 1s and 0s. Those specifically arranged 1s and 0s are sent to the CD burner (for example) which uses a laser to either activate or not activate individual spots on the CD which correlate to whether that spot should receive a 1 or a 0. So now you have a CD with a grid, more or less, of tiny spots, some \"on\" and some \"off\" When you place that CD into a CD player, the player reads which bits of the CD are on or off, turns that back into 1s and 0s which it can then turn back into information that it can send to speakers to produce the same sound waves that were recorded originally. Things get a little different for video/tape. I'll leave that for someone else as I cannot confidently explain it in a way that would be appropriate for this sub."
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f077c0 | How do ad blockers know what to block on any given site? | Technology | explainlikeimfive | {
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"When you visit a website, say URL_0 , the page content including all the text, images, etc. are hosted by the mycoolsite server. But ads on the page aren't hosted by mycoolsite, but served by some ad server like URL_1 . The mycoolsite page just has am instruction for the browser like \"go get an ad from URL_1 and replace this placeholder with the ad\". Adblockers just block requests that go out to known ad servers. There's a blacklist in the ad blocker configuration that lists all the blocked URLs. With adblockers becoming more common, some sites are investing in what's called \"native ads\" where they serve up the ads themselves.This is more work for the site/company since they have to do it all themselves but adblockers can't easily block them. Facebook is a good example. Ads in the news feed are really just special facebook posts that the advertisers pay to put up. And now even with adblock you see ads in the feed."
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f0b5iq | Do walking poles actually aid you on a hike, if so, how? | Technology | explainlikeimfive | {
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"Yes, they do. People wouldn't bother carrying them if they didn't. They take weight off of your legs while walking which reduces fatigue. They also provide two additional points of contact which helps when traversing uneven terrain. They can also be used to feel out in front of you when doing a river crossing.",
"They aid in balance and proprioception... Feeback from the surface. On downgrades they transfer load and impact to your arms reducing muscle fatigue and improving endurance. On inclines they aid in stability. You can walk longer and farther with poles.",
"Everyone else is talking mostly about using the poles to take some of the weight off your legs. This is helpful, but where they really shine is when you're wearing 50 pounds on your back. If you're walking on a grade, or a slippery area, it can be easy to lose your balance and fall. The hiking poles can be used to stabilize yourself, and keep you upright."
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f0bzll | How Did Old Console Mods (Xbox, PS2) Use Official Games Like 007 To Install Unofficial Software? | I've been interested in retro consoles lately, doing a lot of emulating and I have an old Xbox original here that I was curious to see if I could play games I own but only via ISO or img to preserve the discs 😉 To mod it, I need to have a copy of a game called 007: Agent Under Fire (or a few select others) and an original save on the Xbox of that game, plus a flash drive with mod software to copy on it. The real save is replaced by the mod 'save' file and it does its thing and a new OS is installed (well, that's the quick version). Either in the console case or in general, how would a similar vulnerability work on any hardware, how does the mod get access to write to the protected code that controls the copy protection in this or any similar scenario? Did this particular game just simply have a security flaw which allowed someone to find and change the encryption key (that's as far as I could understand)? Or perhaps did they do it another way like by deleting encryption or bypassing it altogether to install a new OS if thats possible? Please Note: I am not planning on infringing any copyrights, I am just curious and like learning about electronics and software. | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"[Here is a full rundown of how the OG Xbox security works and how it was defeated]( URL_0 ). *************************** > Did this particular game just simply have a security flaw which allowed someone to find and change the encryption key [...] or bypassing it altogether In the case of 007, that's basically what happened. Games on the Xbox run with full privileges, so arbitrary unsigned code can be uploaded to memory and run by exploiting a vulnerability in the game save loading system (Explained at 9:20 in the video). Since this code has full access to the console it can modify files on disk and hijack the OS (which requires an other exploit, also explained in the video)."
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f0d06g | How do transparent colors work? | When you put a layer of #0000FF0F on a layer of #FF0000 you can see what both colors are and that the blue transparent layer is on top of the red layer. How? | Technology | explainlikeimfive | {
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"In this case, the extra two characters on the string imply you're using the alpha channel which indicates how transparent that color should be. Like the R, G, and B before it, it's a two-character hexadecimal value which equates to the decimal range between 0 and 255. A value of 0 means the color is fully transparent, and 255 the color is fully opaque. If no alpha value is used, it's assumed you want it to be fully opaque. To draw a translucent layer on top of an opaque one, you would want to use linear interpolation. Basically, this puts the two layers on a linear scale with one being the source, the other the destination, and the alpha value telling how much of each the final product will have. The equation for linear interpolation is typically of the form Ax + B(1-x) with A being one end, B the other, and x a fractional value between 0 and 1. To apply this to pixel colors, we first separate the colors into their different channels (r, g, and b). Then for each channel, you can run the equation to find out the final value. Since the alpha value can range from 0 to 255, we'll take the alpha / 255 to be our 'x'. In the example you gave, it has an alpha of 0x0F (decimal 15), so 'x' is 15/255 and (1-x) is 240/255. Putting this through the color channels, the red channel is 255 * (240/255) + 0 * (15/255) = 240 0 = 0xF0. Green is 0 in both, so it remains 0. Blue is 0 * (240/255) + 255 * (15/255) = 15 = 0x0F. So your final pixel color is #F0000F It can get even more complex if multiple layers have translucency. In which case, you have to take into account the alpha value of both the underlying layer and the top layer. If you want the math you would apply to each channel in this case, you can use the equations found at URL_0"
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f0e0hf | If I'm transferring data from one folder to another in the same SSD, how come the data transfer speed is still so much lower than advertised or tested? | As an example, my Adata XPG S8200 Pro can reach read and write speeds of up to 3500/3000 mb/s and even in testing (using CrystalDiskMark) the supposed speeds are around that range. But when I actually transfer files, even within the SSD, the actual speeds is so much slower? | Technology | explainlikeimfive | {
"a_id": [
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"First of all, are you *moving* the data or *copying* the data? **Moving** the data on the same drive does not actually *move* the information on the physical drive. The OS merely changes the pointer to that data to make it appear in a different location within your filesystem. In other words, the data will still be stored at index XYZ on the drive, but it's folder (the pointer) is now \"D:/Folder 2\" instead of \"D:/Folder 1\" **Copying** data is a much more intensive process. When you do this between 2 different drives, each drive only needs to perform a single operation (i.e. a read operation on the origin drive, and a write operation on the destination drive.) This means that each drive can devote all its available resources to that single operation. However, when you copy data on *the same drive*, that drive now needs to perform *two* operations - reading *and* writing. On a single SSD, the data must be read, written to a buffer, erased and rewritten in steps, all using the same controller and resources on that SSD. This can be *much* slower than if copying between two different drives.",
"Transferring data on the same SSD is not a reliable measure, for a couple of reasons. The first is that depending on how the SSD is connected (for instance if it's SATA) you can't do reading and writing at the same time, because at times it reads and at times it writes. The second is that unless you have partitioned your SSD into multiple partitions, moving data is not really moving the data it is altering the meta data only which can involve lots of random seeks and writes to various places and would be get you closer to your drives random IO performance than sequential IO performance.",
"one of the reasons may be that in order to transfer a file, it's necessary to locate all of its pieces on the drive, then find a new place for them on the drive - probably, not one monolithic area, but much smaller multiple areas. however that was much more important for old HDDs, SSDs are better in that regard."
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f0ege0 | How do emulators work? | How do things like Dolphin, DeSmuME, Citra, and NEStopia work on a computer? | Technology | explainlikeimfive | {
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"At its core, a game console is just running a specialized operating system designed to play specific kinds of games. Virtualizing operating systems is nothing new- programs like Proxmox, Hyper-V, ESXi, etc. have existed for a while and allow one operating system to create a \"container\" and run another operating system inside. Programs like Dolphin et al simply emulate the console hardware, mapping what the console OS expects to see with what is available, and run the console OS inside like a VM.",
"The programs you want to run in the emulator are just instructions (chains of instructions) for a certain target platform, encoded in binary format. So you want to fulfill two steps: 1) decode instruction 2) produce the same result as this instruction would on the emulated platform That's pretty much it. So let's say you're emulating ARM on Intel x86-64. Their instruction sets are different, so you want to create a map: f(x) in ARM translates into z(x) in Intel. n(x) in ARM translates into i(l(x)) in Intel. Et cetera. Then you read, find your translation in dictionary, substitute your data, rinse and repeat. Sometimes, the overhead generates some pretty significant load because not only you often need to convert a single instruction from the emulated platform into an entire instruction chain on your host platform, but you also need to keep track of where you are, added security requirements (there are levels of command execution, which do not always translate, and if you don't pre-analyze them and handle gracefully, it will just crash with limited available debug data), invoke the native instructions, pass through... So yeah. Simple principle, tons of handling."
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f0f66j | What exactly Is the Static On A Tv? | I under why static happens.. what what exactly is it? What is it a bunch of black and white dots? | Technology | explainlikeimfive | {
"a_id": [
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"Background noise of the universe. So the tv antenna is resonating with the band of frequencies it's designed to pick up, and when we send a specific signal comprised of one of those frequencies the antenna resonates and the tv takes the signal and puts it into all the dots on your screen. So the antenna is picking up the random times it's resonates by other causes and it's trying to put that random shit on your screen. This is why the static is often called \"noise\" and why noise can distort your picture. Like when your ear can focus in on one conversation in a crowd of people talking, the rest is just noise. If you take that conversation away all your ear can then hear is noise until you focus on another sound.",
"Analog TV is a wonderful compromise approach. First, there was black-and-white TV, where the signal was the luminance (white-ness). This signal was easy to display, higher values sent more electrons down the TV tube to make the spot on the screen glow more brightly. When Color TV came out, the key was to maintain backwards compatibility with the B & W TV because millions of people owned B & W sets. The color (called chrominance) was encoded as phase shifts in the luminance waveform. B & W TV's ignored this and color ones decoded it. Noise doesn't have any of the fancy phase signaling that generates colors, so your TV is going back to the B & W scheme for understanding the waveform. That's why you see black and white dots, but not green or blue ones. The signal isn't an image, that's why you can't recognize it as anything more than a bunch of dots.",
"It is a combination of background radio noise and imperfections in your amplifier circuit. It is kind of like zooming into a picture too far, you aren't seeing the subject anymore, just random weirdness form the camera that normally doesn't matter. In the case of TV static, in addition to circuit noise, you are seeing radio output from: * blenders, refrigerators, and car starters, anything with an electric motor * microwave ovens, monitors, computers, most anything with a computer chip in it * distant TV and radio stations too faint to resolve into a signal * harmonics from nearby TV and radio stations * atmospheric disturbances * cosmic background radiation, echoes from The Big Bang (seriously!)"
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f0gdve | Can’t any random person broadcast at the same frequency as a radio station and show up when someone tries to tune to that frequency? What do stations do to stop this? Do they have to? | Technology | explainlikeimfive | {
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"They can. The issue is that it's very expensive to broadcast a frequency that goes any reasonable distance. Also, the FCC will come down on anyone who does that like a ton of bricks. It's pretty easy to triangulate a signal to find out exactly where it is, so getting caught is fairly inevitable.",
"It's quite illegal. The FCC (in the us)issues licenses. And broadcasting without a license is a crime. Broadcasting to block someone else's legal signal is even more so. They can triangulate your postion. I'm sure there are similar laws and organizations in most countries.",
"Well, they can actually. However, the FCC (in the states) regulates and enforces frequency licenses for AM and FM radio, and if you broadcast on the same frequency as a local station, they will triangulate your emitter location and knock on your door and pull the plug. But its somewhat moot. FM radio transmitters are several megawatts in power or more, unless you were a serious radio nerd and had the decades scrounging parts and equipment you'd be hard-pressed to overpower a commercial transmitter. And then ones you did the FCC would find you and arrest you. The Cristian Slater movie Pump Up The Volume comes to mind where at the end of the movie, about our hero running a pirate radio station, is driving around town in his jeep broadcasting while FCC vans try and triangulate and track him down. Not sure how realistic that scenario is given the power requirements, but...",
"The short answer is power output. Your basement setup built from radio shack parts won't be able to outdo the wattage put out by a commerical broadcaster. They measure their output in the tens out thousands of watts of \"Effective Radiated Power\". You can probably create some short range interference for them but that's about it. Source: I work in Electronic Warfare.",
"You can try, but unless you can broadcast with more power than the radio station, you're not doing doing anything. That's what radio jamming is. Radio jamming is illegal and the equipment is illegal. If you were very technologically skilled, you could build a jammer that would work in a small area (pretty much impossible to jam an entire radio station over it's entire range), but it's not hard for the authorities to find jammers and shut them down."
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f0l5dw | how do computer monitors work? How does each individual pixel know to change colour? | Technology | explainlikeimfive | {
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"The pixels are each represented by a “bit map” - a block of memory where a 1 turns on or off the r g or b LED or LCD, and other bits control the voltage that flows through it to control brightness. The circuitry that converts the bit map in memory to line voltages for each pixel in the matrix is usually done by a controller board that is built alongside the display."
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f0mr1w | What exactly does fiber internet have/provide that make it better than other types of internet (cable/DSL/satellite)? | I’ve heard fiber internet is the best quality internet you can get. In my area, however, it’s not currently provided. Cable internet is what we currently use, and the package is for up to 300 Mbps. Why would fiber internet of the same speed, up to 300 Mbps, be considered better than cable? If it’s so much better, why isn’t it provided everywhere? | Technology | explainlikeimfive | {
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"Well first fiber wouldn't stop at 300mbps. You could get up to 10gbps (if you have the money). So it is always faster in and of itself. However let's say you artificially throttle the fiberoptic speed so it's only transmitting at the same speed as cable. Even then it has benefits over traditional cable. In that case it has a larger bandwidth than cable. Meaning it can handle more simultaneous information without slowing down, making it great for businesses with multiple internet connected devices. Look at it like this. Traditional cable is a garden hose connected to a fire hydrant. Sure there's a lot of pressure in that tank but that hose can only let out so much water at once at max capacity. Now fiber optics is like connecting a genuine fire hose to the hydrant. So much more water is able to flow out at max speed, and even when the pressure is regulated more water will exit the end of the fire hose at once than the garden hose."
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f0ozwv | How does NASA know exact trajectories and locations of space craft in interplanetary space? | Technology | explainlikeimfive | {
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"2 things. First is simple physics. Once a spacecraft is on a trajectory, it doesn't change. Once you calculate a trajectory and burn the engines to put the spacecraft on said trajectory, you know it's there because there's nothing to make it go anywhere else. Second is tracking. We have to communicate with spacecraft, which means sending and receiving radio signals. If we're sending and receiving radio signals, we obviously know where they're coming from and where they're going. That tells us where. To get a trajectory, we just track the signals over a period of time and then plot out the rest, because, again, the laws of physics allow us to calculate it."
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f0qp4x | Why do some PlayStation one game discs have a blue coloring while others are black? | Technology | explainlikeimfive | {
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"Former Sony employee here. I worked in the Replication factories where PS1, PS2 and PS3 games were made. PS1 games are constructed like CD's. One thick Polycarbonate wafer is injection molded with data on the label side. That side is metalized then a protective coating is spun over the metalization. Then the label applied. PS2 games are constructed like DVD's. Two thinner wafers are injection molded with data on one side, then metalized and adhered to each other, data sides in. The label is applied on the \"B\" side wafer. PS3 games are constructed like Blu-ray discs. One thin wafer is injection molded with data on one side then metalized. Additional layers are spun-coat then stamped and metalized on top, and a final protective layer is spun on the data side and the label is applied on that side as well. A protective hard coating is then applied to the read side. The polycarbonate used in PS1 discs is just dyed a very, very dark blue that looks black. Since the wavelength of the laser diode in a CDROM drive is 780nm (near infrared), the signal isn't attenuated by the dye. It serves no purpose other than to look different from other discs. In fact, Sony piloted a program for music CD's that used the same resin and a novel printing method on the label side to simulate the appearance of a vinyl album. They played in normal CD players with no issues. The polycarbonate used in PS2 discs was again just dyed blue, slightly less dark than the PS1. It again serves no purpose other than to differentiate the discs from PS1 and other discs. The wavelength of a DVD-ROM drive is 650nm (red) so again no signal interference occurs. The copy protection method used in PS1 and PS2 discs do not rely on the dye; rumors to the contrary are false. Since the PS3 uses Blu-ray technology, with a 405nm wavelength (violet) Sony couldn't dye the polycarbonate and instead left it clear. Thank you for coming to my Ted talk."
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f0qwm1 | How does torrenting files (movies, shows, etc.) work? | Technology | explainlikeimfive | {
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"Instead of just connecting to one single server that hosts the file you want, your torrent software downloads pieces of the file from several other users (called peers) that already have those pieces. At the same time, the pieces that you have already downloaded get shared with other users. A service called a *tracker* keeps track of all the connected users and which pieces they have. URL_0",
"The torrent file itself is just a list of jigsaw pieces that make up the files you want, and a list of seed addresses (i.e. people who once had all the pieces). You contact the seed addresses and not only do they tell you what pieces they have, but they tell you who else they know has asked for them, and what pieces \\*those\\* people have. You can then contact all those people too. And they'll tell you what pieces they have, and who else they have given pieces to, or taken pieces from. Within a few minutes, you are able to talk to almost everyone who's online and has those pieces, and even if there aren't many people who have every piece, you can still talk to everyone and ask them to send you the pieces they do have. And generally, when someone asks you for a piece that you have, you send a copy of it to them. Because there's some randomness in it (i.e. you don't always send piece 1 first if someone wants pieces 1, 46, and 257 to \"complete their set\"), and there are lots of people trying to get the files, you are able to have hundreds of people sending you data at the same time, and that data might well cover the entire jigsaw (though maybe not immediately). Even if those people themselves don't have the full jigsaw! Person A might have pieces 1, 2, 6 and Person B have pieces 3, 4 and 5, and you might have no pieces at all - but that means if you all talk to each other, you can all get the entire (6-piece) jigsaw. It's designed so that the original \"seed\" (i.e. the very first person to put the jigsaw online) doesn't need to send thousands upon thousands of copies of the file... they send out pieces to everyone, and when everyone has else enough pieces, the original seed could even go offline and it wouldn't matter. Eventually everyone else will talk to everyone else and all the pieces will be collected and as soon as one person completes their jigsaw (i.e. gets the complete file), they can either go offline or, if they are polite, \"seed\" (stay online and keep handing out pieces of the puzzle to other people who are missing pieces). Advantages: Because there is no central server, it's hard to shut down. Only one person needs to have had the complete file, at some point, for it to be available to everyone. So long as they gave away enough pieces to start, they can disappear and it doesn't matter. Because you're sharing pieces, it's hard to scam - eventually people won't give you the pieces you want because you're not giving up the pieces you have, but which they need. The software tends to enforce this, it's not required (seed-ratios, etc.) Once you contact \\*one\\* person who is online and has any of the jigsaw pieces, they will share everything they know with you too... so soon you can contact \\*everyone\\* who has jigsaw pieces. Hence you have to shutdown EVERY person involved to completely remove the torrent. Because dozens of people are sharing pieces with dozens of people, you can download very fast - literally dozens of people are trying to send you pieces they have, and get the pieces they want from you, and usually enough of them can swamp your connection easily. Disadvantages: If there aren't enough people online with the right pieces, you can never download the full file. Your IP address will show up in a list of everyone downloading the torrent. Record companies, movie companies etc. have used this as evidence before that you were illegally downloading their content - they just join the download and EVERYONE tells them everyone else they know who is downloading the file.",
"All your friends in school know a story, but none of them are allowed to tell you the story. So instead, each of them gives you one word of the story, and at the end of the day you have the full story. The teachers don't want them to tell you the story, but they can't prevent you from sharing words with each other, therefore it is nearly impossible to stop the story from being shared."
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f0s15n | Why were older game discs able to be put into the system and instantly played, when now you have to download the entire game first? | Technology | explainlikeimfive | {
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"Because the older games had the entire game stored on the disc, and now there is only a part of it on the disc and the rest has to be downloaded. It allows them to make games bigger, more complex AI, better graphics, and the backbone of the games more complex than a single disc could hold, but also allows for updates to bugs in the code.",
"They *weren't* able to be instantly played. They had long loading times and [associated loading screens]( URL_0 ) while the necessary parts of the game were downloaded into the game system's memory. Games back then were a lot smaller so it wasn't economical to put a hard drive into the system - it was cheaper to have volatile memory and just download the part of the game that you needed when you needed it, and players would just have to wait for a moment for it to get loaded into that memory. Today, games are *way* bigger. There's a lot more stuff that needs to get loaded into the memory before it's playable. And while technology has greatly increased the amount of data that an optical disk (like a DVD) can hold, there is a hard physical limit to how fast that data can be read off of the disk. Hard drives, on the other hand, have gotten much bigger, much cheaper, and much faster. So rather than force you to wait through *exceedingly* long loading times every time you walk through a door the method is to make you wait through a single very long, thoroughly boring load time while the game is downloaded and installed, either from the disk or from the internet. And since printing and shipping *any* kind of physical disk costs money, it's cheaper for developers to release the bare minimum needed on the disk, or even nothing at all, and allow the device to download most of the game from the internet. Once the game is installed on the device, it doesn't need to pull much, if anything from the disk. After install, usually the disk is only needed as verification that you still own the game. Without that check, you could install the game from the disk and then hand it to a friend and let them download the same game from the same disk and get the game for free. There are still loading times, of course, because the game still has to load from the hard drive into the RAM, but it's *significantly* faster than if the game had to load from an optical disk or the internet. Old cartridge games didn't have this problem because cartridges act more like RAM than a disk. They're faster because you don't have to wait for the device to physically move something in order to find the data (like physically locating where data is on a disk). The downside to cartridges was that, at the time, they couldn't hold nearly as much data as an optical disk, so games were limited in size.",
"Another factor that was taken in consideration when they did this change was the fact that the disc reader in ps1, ps2 and Xbox would fail frequently. Since all the game was inside the disc, they needed to read the disc at all times, which leads the reader to fail. Nowadays you only use your disc reader for a few moments and then all the data is inside your system HDD, almost not using the disc and it's reader.",
"In previous decades and generations there were no patches, or updates, and the whole game needed to be on the floppy, cartridge or disc that was sold. Systems also didn't have any, or much memory at all, and could not store games. The size of today's games makes it hard for them to entirely fit on one disc, so sometimes developers will force you to download parts of the game. Some games use discs as unlock keys, essentially, making you download the rest. For instance, one recent MX game had 244-300mb on the disc and required a 24gb download, which made me decide not to play it because it would've taken me 9-10 hours to download. I've also read something about the disc drives not being capable of reading modern games like they used to, in the insert and play kind of way. The games are so big that it's better to install them onto hard drives and run them from there, which is why you have to install. That said, a lot of modern games do fit on one disc, and are complete. However, they often get patches on day one or before, for reviewers. Games I've gotten early have been updated once or twice before release. But, if a game doesn't have any updates and is fully on the disc you've bought, no downloading will be required. The console installs the full game from the disc, meaning you're not using your network for anything."
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f14eio | Why does a remote with a low battery work like new for a while after I smack it? | Technology | explainlikeimfive | {
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"Already been asked before but I’ll copy my answer here: Batteries work by electrons being stripped from a piece of metal with acid and pushed through a wire. When the metal is degraded too much, there’s no more electrons to strip off it and the battery no longer works. When you slap the remote the acid hits parts of the metal that may not have been soaking as much and shakes any potential lingering electrons off making them available to be pushed through the wire. Imagine you vacuum a dusty rug and it looks pretty good but then you pick it up and slap it and some dust debris still flies off. Same idea.",
"Sometimes it can be less about the battery strength and more about the connection. Typically what's happening in this situation is that the connections are becoming stronger after hitting it. Then over time, the batter shifts just slightly and the connection is not as strong this causing issues.",
"It's not the smacking, just open the battery compartment and spin the batteries to get a better contact.",
"You get pretty much the same reaction if you move the batteries in any way. Take them out, reverse them if there's more than one. Take them out and shake them. Shake the remote. Put it on a heating vent or in the sun. All of these *seem* to work even better if you do a random incantation. Also, btw, just letting the remote sit there for awhile untouched sometimes gets you a few more clicks. It's all about disturbing in any way the connection itself or the distribution of chemicals within the battery, or letting capacitors recharge, etc. It's all very minimal and short-lived if the battery is really depleted.",
"I have been flipping the supposedly dead, no-brand batteries in a TV remote for about five years. It’s beyond weird now. E: some peculiar autocorrect!",
"Tiny bits of oxidation occur between the battery terminals and the contacts in the remote that over time can in some cases impede electrical contact. When you move the batteries around it \"breaks up\" that oxidation just enough to make a bit of renewed contact.",
"Knocking bits off the plates in the battery to expose unused/conductive anode/cathode. While many say it is the connection between the battery and the remote, I find that only very old and near fully depleted batteries suffer from this. And on heavier loads like a flashlight, you can see it get significantly brighter when wacked, Yet only nearly dead cells need this, you won't find a flashlight with new cells that has been sitting for months need to be hit to get full brightness. It also has to be wacked more and more as the battery dies. If it was oxide buildup on the connections it would matter more on how old the battery is and not its state of charge.",
"The metal of the battery terminal and the metal of the contact within the battery compartment both corrode over time. That corrosion is non-conductive, and it can diminish the metal-to-metal contact of the battery and the remote. Physically jarring it, or opening it up and spinning the batteries breaks up the fragile layer of corrosion and restores the metal-to-metal contact. Note: dust and dirt will do the same thing and can be fixed the same way.",
"Don't do that but if you bite in a battery just crushing it a little bit, it definitely gets a second short life. Source : I was a poor kid, had to do it to keep playing my friend's game boy. Don't do it, it's not safe obviously."
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f17myj | what are the strips and chips for on debit/credit cards | I noticed my ID cards similar set ups one has a chip the other a strip. What do they do on the debit card? Do they serve the same purpose? | Technology | explainlikeimfive | {
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"The black strip is a magnetic strip, it's how credit/debit cards originally functioned before chips (which came out relatively recently). The black strip contains information like the name of the account ohlder, account number (usually the same as the actual number printed on the card), expiration date, PIN, etc. Chips work a little differently - for *physical* transactions (like at a gas pump or in a store) they send unique packets of information each time, which means even if the info gets hijacked a thief won't be able to do anything with it the next time. But that's just one specific case where chips are more secure. People can still just take your credit card number, expiration date and CVV code and go around ordering stuff online, since the chip plays no role at that point."
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f19zj7 | How is rosin for string instruments made and what discerns quality? | Technology | explainlikeimfive | {
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"Violinist here. Rosin is made mostly from an artificial resin or a tree sap. Characteristics of good rosin: - naturally made, tree sap, (I’ve seen some rosins made from honey) - made in Italy or France - high quality case/storage materials",
"It is there to bring friction between the bow hair and string. How it is made is actually quite simple. With natural rosin you simply collect sap trees by tapping them, drilling a hole then putting a tap in so it flows out. Then you distil the sap to collect rosin. Then you heat it to melt it and pour it in to whatever shape you want.",
"Rosin, or Resin is a solid obtained from the sap of various species of trees, mainly conifers such as pines or firs. Traditionaly, the sap was harvested by carving the bark of the tree in a series of v-shaped cuts, then placing a collecting jar at the base of the grooves. The collected sap was then heated in a closed vessel to evaporate turpentine. Historically, turpentine was a valuable solvent and cleaner. The leftover solids are rosin. Different trees produce rosin with different qualities. The heating process also alters the properties of the rosin depending on how it's carried out. Rosin can also be recovered as a byproduct from the paper making process. Various stages in the process separate oily compounds from wood chips which would contaminate paper produced thereby. However, high quality rosin used for traditional arts and crafts such as violin bows is usually extracted from stumps of conifer trees, the rest of the tree being used for lumber. The stumps are cleaned and chipped. The chipped material is rinsed with a light solvent which dissolves resin particles. The solvent is then heated to evaporate it leaving the extracted rosin behind. Further chemical processing using different solvents can separate different chemical constituents in the rosin producing different grades."
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f1brdq | How are explosives manufactured without exploding? e.g grenades, c4 | Technology | explainlikeimfive | {
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"Modern explosives need something to set them off, without the initiator they are inert and can be handled perfectly safely without any danger of an explosion, some even can be eaten.",
"Secondary explosives like TNT or RDX are relatively stable and can be handled, stored, and even melted without much issue. Primary explosives however (those used to initiate detonation in a secondary explosives) need to be handled and manufactured in very specialized and controlled conditions, since friction, shock, and heat can set them off. What these conditions are depends on the explosive being manufactured. In a lot of cases, processing is done in a \"wet\" state, where the explosive compound is dissolved or mixed with a solvent. This lessens their sensitivity during manufacturing. Drying off the solvent returns the explosive to its sensitive state. Tools and containers for processing/handling the explosive compounds are usually made of soft materials like wood or rubber. For stuff like nitroglycerin, the ingredients are kept cold during mixing, and forced air nozzles are used instead of mechanical stirrers. Generally in all cases, the explosives have to be made in small batches at a time to lessen the risk of accidental detonation. EDIT: I just consulted my copy of \"The Chemistry of Powder and Explosives\", and there is an interesting subsection on how detonators for dynamite were made in the early days. A rectangular rubber mat placed behind a concrete barrier is used to mix small batches of mercury fulminate and potassium chlorate powder together. Wires attached to the corners of the rubber mat to allow them to be manipulated by a worker at a distant. By repeatedly lifting and lowering the corners, the ingredients on the mat are thoroughly mixed together. The mixed explosive powder is then carefully pour into a rubber bowl, and carried to another location to be filled into caps. Note, the book then states that the powder loaded into the caps are then subject to a pressure of 2900 psi by a press with a wooden rod to compact it.",
"Explosives is a broad term, there are explosives that are very sensitive which are used to initiate an explosion and explosives so inert you can set fire to them and they will just burn like a piece of wood. Most explosive devices contain mostly inert explosives like C4 which you can add to anything with as much danger as handling clay and the sensitive explosive initiator is only added when you are ready to blow up something. That being said the manufacturing of any explosive is extremely dangerous and handled with extreme caution, and still from time to time accidents occur (usually these are in fireworks plants handling fire sensitive black powder maybe with less stringent regulation; producing C4 is dangerous during the process but the finished product won't accidentally explode, and producing sensitive explosives is done in smaller quantities and with great care and very strict regulations due to the extreme risk)."
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f1hxzq | How does a string of numbers become a video game? How does binary code become images and sounds you can interact with? | Technology | explainlikeimfive | {
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"The numbers are binary. When you program with words, that interface converts the words to binary numbers for the actual computing. Those numbers direct EVERYTHING. for the image, they print one pixel on the screen at a time. The numbers tell it which positions to be in (pixel location on screen) along with what colour to be. For the size of objects it’s easy to use math. Think 2x2 pixels for a small square image and 10x10 pixels for a large square. That’s all math, is which is what computers were made for. The computer has a processing speed, say 2 gigahertz. That means the processor processes 2,000,000,000 calculations per second. Imagine playing battleship with your friend. He tells you A1 is red. A2 is red. A3 is blue. A4 is red. A5 is blue. And so on. That is what is happening when the pixels are told what to do and how it knows which pixel should be what colour. Computers and game consoles need to “load” a level before you can start playing because even at 2,000,000,000 calculations per second it can still take a while to process all the variables. For a shoot ‘em up game, the computer uses more math for hitpoints. It knows you are at 88% health and just keeps subtracting as you get hit more. It knows that when the enemy’s health gets to zero that it needs to process another action (enemy dies). It’s like when your doorbell rings you know to go answer it. Computers do one thing at a time (mostly). So it’ll update every single pixel on the screen, and then adjust the hitpoints of all the players, then update all the pixels on the screen, then update all the hitpoints of the players. And so on. It does that for every process, like looking for button presses or stick movement. Sometimes it may not even change anything. For example, it checks to see if you’ve been hit by another player. If not, it does NOT subtract anything from your health. X button is STILL not being pressed? Then it continues to do nothing. When you eventually press the X button then it will initiate the sequence of events that are to happen. Computers keep all the variables and screen colours separated by “addresses”, just like how your mail man only delivers your mail to you. You can think of your neighborhood like a screen made up of pixels. Each house is a pixel. It’s one mail man but everyone gets their mail every single day. It just takes time. Computers freeze when there is an error and it doesn’t know what to do. Imagine if you went to check your mail and there was an elephant in the mail box. You would have no clue how to deal with that. Remember, this is 2,000,000,000 calculations PER SECOND. That is a lot of stuff to check and a lot of numbers to crunch. It’s really amazing but keep in mind the first calculator was the size of a house and all it did was add numbers. What you are seeing is the culmination of decades of advancement in technology to make all this magic happen. EDIT: Thank you, kind person, for the silver. =D EDIT: And thank you again for the gold!! =D",
"The 1's and 0's are grouped into short sequences with specific meaning. Example: 10010000 equates to the x86 instruction \"NOP\" - short for \"No Operation\". Literally, do nothing for 1 CPU clock tick. Other sequences equate to other things. Large complex things are built out of these simple things, much like a lego set.",
"How do a bunch of atoms become a person? How to random squiggles become a book? How does a pattern of light and shadow become a movie? Organization. Smaller things are organized into groups that have properties not present in any of the individual pieces. Something that understands that organization can interpret it and extract information from them. These groups themselves are organized into larger and larger groups, squiggles into letters, letters into words, words into sentences, until complex messages are being conveyed, messages completely divorced for their constituent parts.",
"First, one thing you can’t guess: a string of binary code just represents a plain old number. For instance, 1011010 means 90. 101101010110101011010 means 1,486,170. I won’t explain here how one becomes the other because that’s a bit mathematically tedious, but just note that every number translates as a binary string, and every binary string translates as a number. (Why 1s and 0s for computers? Because electronics works with electricity, electricity is either on or off, two states, 1 or 0.) — Alright now that you know that, when you think about it, it’s outrageous the kinds of data you can represent with numbers. — Take a letter for instance. “E” is the 5th letter of the alphabet; so if you decided to use that alphabet, the binary code representing 5 could mean “E”. Or you could use a different alphabet, one with all the lowercase and uppercase letters, and maybe it could have a ton of special characters and punctuations too. Oh, and optionally, it could contain Cyrillic characters so you can also write in Russian, French accents, etc. If you can represent one letter with one number, then BAM! you can represent all the books in the world as a sequence of numbers. Fun fact: bugs from using the wrong “alphabet” (encoding format) for a piece of data are among the WORST to figure out, as you can imagine. It would happen a ton decades ago, but thankfully are more rare now that most of the industry has ended rallying around one called “UTF-8”. — Take a color. A rainbow goes from red to purple and meets all colors, so you can set a number for the distance from red for instance. A rainbow doesn’t get colors darker, so you can set another number for how dark. With those 2 numbers, I believe you can represent all colors you could ever need. The way a computer typically does it though is not like that: it takes a value of how much red, of how much green, and of how much blue, and it mixes them up like paint. It’s less visually imaginable, but you can trust me that with those 3 numbers, you can also represent all colors you could ever need. This is called RGB (Red-Green-Blue, how original). Say you have an image of 1000 pixels by 1000 pixels. So, that’s 1,000,000 pixels to represent. You can just spell each color of each pixel (that’s what the “bitmap” format does), and with 3,000,000 numbers, BAM! you’ve got your image. Fun fact: there are ways that are much less resource-intensive to describe an image with numbers than by painstakingly spelling out the color of each pixel. I won’t get into how each works, but their names will be familiar: JPEG, GIF, PNG, ... — Take a music note. The height of the note really is its frequency, which is a number; and you can have another number for how strongly the note was played for instance, if it’s relevant to the instrument. Each instrument gives a certain frequency and strength (or several, if it’s an instrument that allows to play several notes at once), so combine together the right frequencies/strengths, from the right instruments at the same time, each note at the right time (which is also a number), and BAM! you’ve got a symphony. That’s how digital music (like the MIDI format) works. Full disclosure: I have no idea how recorded sounds (Wave, MP3, ...) work, but you can take my word for it that it’s all also series of numbers. — Take a point on a sheet of paper on a table. You can define the distance of that point from the top of the sheet (let’s call that value Y), and from the left side of the sheet (let’s call that value X), and you can represent any point on the sheet with those 2 numbers. Throw in a 3rd number for the altitude of the point (let’s call it Z) so it can be higher or lower than the table, and if you are willing to set every number even very high or very low for those 3 numbers X, Y, and Z, you can basically represent any point in the whole space around you. Now, think of the shape of a soldier in a video game. That soldier is just a collection of dots at the exact right spot in space (each 3 numbers), those dots each have a certain color (also numbers), that soldier makes noise and speaks to you (sounds, which are also numbers), and you may see their name and health metrics above their head in plain text (also numbers). You take a step towards the soldier: this just makes the first-person camera of the game change its values for X and Y in space, that’s still number stuff. The soldier raises an arm, several parts of his body move separately their values of X, Y, and Z so they change position in space, in a way that together, it almost feels like a natural, human movement. Still numbers, all that. And BAM! you got a video game. All with numbers. All represented with binary code.",
"In a word: Interpretation. The numbers that make up a computer program such as a video game, are either data or instructions. Instructions are commands that the programmer is telling the CPU or some other component to process. The numbers map to a predefined set of instructions that the processor understands because of the way it was manufacturered, called the instruction set. Ever heard of x86 or x86-64 (aka x64)? Those are instruction sets for CPUs. They already define which number means Add, Subtract, Store, Retrieve, Compare etc. And with this basic machine code you can build software\\*. *Instructions are numbers that are interpreted by the processor to perform low level computations that make up the program.* Data is the content that will be used by the software. These numbers could represent colors, shapes, text, sounds, anything. How exactly a set of numbers can represent this content, depends on the type of content. Colours can essentially be represented by levels of Red, Green and Blue light, plus maybe Alpha (transparency); shapes can be coordinate points in a virtual space; text can be ASCII code points; sounds can be voltage levels representing sound pressure. It's the software's job (the instructions that the programmer writes) to specify what data represents what type of content, and what to ultimately do with it (decompress it, transform it, send it to the monitor, speakers, etc). *Data is numbers that represents a range of types of information and multimedia.* \\*Nowadays of course, programmers rarely write software in this low-level machine code, they use programming languages that abstract away these details",
"With lots of them. 0: this is 1 bit. It can be 0 or it can be 1. We can count 2 values with it. Why 0 and 1? Because we’re dealing with electric voltage, it’s easier to read a low voltage, say 0 and a high voltage, say 5, than it is to have multiple voltages because of the way electricity works and errors that can arise. You don’t want to accidentally read the wrong value. 00000000: this is 8 bits. Also known as 1 byte. Each bit can be 0 or 1, with 8 bits we can count 256 values. 00000000 = 0 00000001 = 1 00000010 = 2 00000011 = 3 00000100 = 4 Etc etc. 000000000000000: this is 16 bits or 2 bytes, with it we can count 65356 values. Each value can be assigned a particular operation or function that the microprocessor carries out. A computer will be designed to count a certain number of bits at a time. Of course, we don’t do this. Nobody codes games in binary, it’s incredibly hard for people, incredibly easy for computers. So there are layers, at the top layer there is the final product. This will be coded in a language people can understand easily, that’s what you see. Under that is another language that’s less easy. Below that another one and so on and so forth, all the way down to machine code, binary. When you’re playing a game your computer is basically counting millions and millions of numbers incredibly fast, it is computing numbers, that’s what computers do. All these numbers tell it what to do."
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f1j39e | What causes a program to lag? | Imagine you finished browsing on chrome and want to end your session... You click on that red X to close everything... And then your computer just hangs there. What causes this lag? Theoretically shouldn't the computer be erasing stuff from memory, not lagging? | Technology | explainlikeimfive | {
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"Your computer lags because there is insufficient resources available to perform tasks in real time. Resources include CPU time, the amount and speed or you RAM, and how long it takes your hard drive to catch up. Hard drives are by far the slowest component of your computer, so the less time you spend reading + writing to it the faster your computer will be. If you are short on RAM your computer will begin dumping RAM contents to your Hard drive to free up space. A process called swapping. It's also possible your CPU is busy doing something else like loading another program. Sometimes though it's bad code. The program is written in an inefficient manner which causes it to use an unnecessary amount of resources for a given task."
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f1k3no | What causes computerized technology to screw up so often (glitches, freezes, shutdowns) if its all based on calculations? | Technology | explainlikeimfive | {
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"Garbage in Garbage out, meaning human error. Computer glitches by calculation error ARE SUPER ALMOST NONEXISTENT rare. But shitty coding and bugs are common. If you have a infinite loop in your app, call X which calls up Y which refers back to X, will take the computer on a journey, which ends you pissed off and the computer glitching out. Sometimes the computer can powerthrough these, but it doesn't solve it, it's just there, and with more and more of these oversights, the computer breaks. forcing a shutdown.",
"Computers do what you tell them to do, not what you want them to do. Technically they just do the computations, but if they do the wrong ones or if they’re in the wrong order, bad stuff happens. Humans are the ones that tell computers to do and humans aren’t perfect. The things we expect computers to do are more and more complicated and rely on coordination with lots of other people. Any mistake or miscommunication results in computations about the wrong thing or with wrong information. At some point, the wrong information causes errors. The computer might have instructions to do something that can’t be done with its own resources, or it might be told to do something that leads it into an infinite loop, or it might run into a scenario it doesn’t have instructions for.",
"The reason for most mysterious computer problems is precisely because computer programs follow precise logical pathway, even when a human wouldn't. Consider a program that wants to load an image. It expects the image to be stored in a file called image.jpg. It tries to load that file, but it doesn't exist (maybe someone else deleted/moved/renamed the file). The program wants to load image.jpg. It tires to load the file, but it doesn't exist. The program wants to load image.jpg. It tries to load the file, but it doesn't exist... And so on. A human would give up quickly on trying to load the image, or maybe try looking elsewhere. A computer will try forever. A lot of making code robust to bugs is explicitly telling the computer to be less deterministic. In this case, you would want code that, instead of saying \"load image.jpg\" says \"Try to load image.jpg for 5 seconds, then give up.\""
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f1oomf | Why are games rendered with a GPU while Blender, Cinebench and other programs use the CPU to render high quality 3d imagery? Why do some start rendering in the center and go outwards (e.g. Cinebench, Blender) and others first make a crappy image and then refine it (vRay Benchmark)? | Edit: yo this blew up | Technology | explainlikeimfive | {
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"Games and offline renderers generate images in very different ways. This is mainly for performances reasons (offline renderers can take hours to render a single frame, while games have to spew them out in a fraction of a second). Games use rasterization, while offline renderers use ray-tracing. Ray tracing is a lot slower, but can give more accurate results than rasterization^[1]. Ray tracing can be very hard to do well on the GPU because of the more restricted architecture, so most offline renderer default to the CPU. GPUs usually have a better computing power/$ ratio than CPUs, so it can be advantageous to do computational expensive stuff on the GPU. Most modern renderers can be GPU accelerated for this reason. > Why do some start rendering in the center and go outwards (e.g. Cinebench, Blender) and others first make a crappy image and then refine it (vRay Benchmark)? Cutting the image into square blocks and rendering them one after the other make it easier to schedule when each pixels should be rendered, while progressively refining an image allows the user to see what the final render will look like quickly. It's a tradeoff, some (most?) renderer offer the two options. ************ [1] This is a massive oversimplification, but if you are trying to render photorealistic images it's mostly true.",
"Software engineer here. There's a lot of wrong information in here guys... I cannot delve into all of it. But these are the big ones: (also, this is going to be more like an ELI15) A lot of you are saying CPU render favors quality and GPU does quick but dirty output. This is wrong. Both a CPU and GPU are chips able to execute calculations at insane speeds. They are unaware of what they are calculating. They just calculate what the software asks them to. **Quality is determined by the software.** A 3D image is built up by a 3D mesh, shaders and light. The mesh (shape) of which the quality is mostly expressed in amount of polygons, where high poly count adds lots of shape detail but makes the shape a lot more complex to handle. A low poly rock shape can be anywhere from 500 to 2000 poly, meaning amount of little facets. A high poly rock can be as stupid as 2 to 20 million polygons. You may know this mesh as wireframe. Games will use the lowest amount of polygons per object mesh as possible to still make it look good. Offline renderer projects will favor high poly for the detail, adding time to calculate as a cost. That 3D mesh is just a \"clay\" shape though. It needs to be colored and textures. Meet shaders. A shader is a set of instructions on how to display a 'surface'. The simplest shader is a color. Add to that, a behavior with light reflectance. Glossy? Matte? Transparant? Add those settings to calculate. We can fake a lot of things in a shader. A lot of things that seems geometry even. We tell the shader to fake bumpiness and height in a surface (eg a brick wall) by giving it a bump map which it used to add fake depth in a surface. That way the mesh needs to be way less detailed. I can make a 4 point square look like a detailed wall with grit, shadows and height texture all with a good shader. Example: URL_1 This is purely a shader with all texture maps. Plug these maps in a shader in the right channels and your 4-point plane can look like a detailed mesh all by virtue of shader faking the geometry. Some shaders can even mimic light passing through like skin or candle wax. Subsurface scattering. Some shaders emit light like fire should. The more complex the shader, the more time to calculate. In a renderend frame, every mesh needs it's own shader(s) or materials (configured shaders, reusable for a consistent look). Let's just say games have a 60 fps target. Meaning 60 rendered images per second go to your screen. That means that every 60th of a second an image must be ready. For a game, we really need to watch our polygon count per frame and have a polygon budget. Never use high poly meshes and don't go crazy with shaders. The CPU calculates physics, networking, mesh points moving, shader data etc per frame. Why the CPU? Simple explanation is because we have been programming CPUs for a long time and we are good at it. The CPU has more on its plate but we know how to talk to it and our shaders are written in it's language. A GPU is just as dumb as a CPU but it is more available if that makes sense. It is also built to do major grunt work as an image rasterizer. In games, we let the GPU do just that. Process the bulk data after the CPU and raster it to pixels. It's more difficult to talk to though, so we tend not to instruct it directly. But more and more, we are giving it traditionally CPU roles to offload, because we can talk to it better and better due to genius people. Games use a technique called Direct Lighting. Where light is mostly faked and calculated as a flash. As a whole. Shadows and reflections can be baked into maps. It's a fast way for a game but looks less real. Enter the third (mesh, shader, now light) aspect of rendering time. Games have to fake it. Because this is what takes the highest render time. The most accurate way we can simulate light rays onto shaded meshes is Ray tracing. This is a calculation of a light Ray travelling across the scene and hitting everything it can, just like real light. Ray tracing is very intensive but it is vastly superior to DL. Offline rendering for realism is done with RT. In DirectX12, Microsoft has given games a way to use a basic form of Ray tracing. But it slams our current cpus and gpus because even this basic version is so heavy. Things like Nvidia RTX use hardware dedicated to process Ray tracing, but it's baby steps. Without RTX cores though, RT is too heavy to do real time. But technically, RTX was made to process the DirectX raytracing and it is not required. It's just too heavy to enable for the older GPU's and it won't make sense. And even offline renderers are benefiting from the RTX cores. Octane Renderer 2020 can render scenes up to 7X faster due to usage of the RTX cores. So that's really cool. --- edit Just to compare; here is a mesh model with Octane shader materials and offline raytracing rendering I did recently: URL_0 (took just under an hour to render on my RTX 2080S) And here is the same mesh model with game engine shaders in realtime non-RT rendering: URL_2 (took 1/140th of a second to render) Different techniques using the hardware differently for, well, a different purpose ;)",
"Can you ask this question like I'm five?",
"GPU = quick and dirty. CPU = slow but perfect and doesn't need expensive hardware. If you're rendering graphics for a movie, it doesn't matter if it takes an hour per frame, even. You just want it to look perfect. If you're rendering a game where it has to be on-screen immediately, and re-rendered 60 times a second, then you'll accept some blur, inaccuracy, low-res textures in the background, etc. How the scene renders is entirely up to the software in question. Do they render it all in high quality immediately (which means you have to wait for each pixel to be drawn but once it's drawn, it stays like that), or do they render a low-res version first, so you can get a rough idea of what the screen will look like, and then fill in the gaps in a second, third, fourth pass? However, I bet you that Blender, etc. are using the GPU just as much, if not more. They're just using it in a way that they aren't trying to render 60fps. They'll render far fewer frames, but in perfect quality (they often use things like compute shaders, for example, to do the computations on the GPU... and often at the same time as using the CPU).",
"Blender can also use the GPU, most render farms for blender do use the GPU since it is faster and cheaper. Games and such use a different renderer.",
"These are all different programs each with a different way of rendering graphics. GPUs tend to render the image as a series of triangles with textures on them. This is good enough for video games and more importantly with the GPU it can be done in real time so you can get 60-120 frames per second without too much issue. Lighting calculations must be done separately and you've likely seen video games produce crappy shadows for moving objects and maybe have a setting to control how good they look in exchange for CPU performance. You CAN make GPUs do rendering differently, but you have to write the code to do it yourself rather than using Direct3D or OpenGL to do it for you. This can be difficult to do as it's like a whole new language. These other programs use different methods of rendering. What matters most though is they are doing it pixel by pixel and take the properties of light and reflection very seriously. The shadows produced will be as close to perfect as possible taking into account multiple light sources, point vs area light, and reflections. Consequently they look VERY good but take a lot longer to render. Starting from the centre and working your way out is just a preference thing. Some renderers start from the top-left corner. But since the object in question tends to be at the centre of the camera shot and these renders take a while, starting from the centre makes sense in order to draw the thing in frame most quickly. vRay renders the whole frame at once rather than starting in a small spot and working its way out. I don't use it, but from seeing other benchmarks I suspect it works by firing light rays from the light sources (eg: the sun) which find their way to the camera rather than firing scanning rays from the camera to produce an image more consistently. This means the image is produced chaotically as photons from the sun find the camera rather than the camera discovering the scene lit by the sun.",
"Most of Ray Tracing renders like vRay or Cycles had options for GPU rendering for long time. Problem is that heavy scenes need large pools of memory something that wasn't available for GPUs until recent. If GPU can't load a scene into it's memory it simply can't render it at all which means despite CPU being slower it's still better because it can complete task, CPU can have terabyte of RAM... however with more modern CUDA GPU can also use RAM in addition to VRAM for rendering. Games heavily optimized to be used in real time renders with stable FPS and fit into GPU memory, while scenes in Blender or other 3d packages aren't and usually much more heavy. > Why do some start rendering in the center and go outwards (e.g. Cinebench, Blender) No real reason as example Blender have options for this, centre is good because that usually focus of the picture, why would you want to spend time rendering corner that might not show potential errors... > and others first make a crappy image and then refine it (vRay Benchmark)? More samples, more precision.",
"There are both CPU and GPU renderers for offline rendering. GPUs have massive scalability and so more and more people are using them because they can just throw in another gpu and increase their render speed whereas with a CPU you might have to change your entire system. Games are heavily optimised and rul alot better on GPU due to the amount of precomputation that is usually done to optimise loading times and things like that.",
"...Blender (cycles and Eevee) does use GPU.... What are you on about?",
"Almost every 3D software has its own rendering engine that's different from others by the kinds of calculations it does in order to produce an image. - Videogame engines are optimized to do rendering in real-time, and GPUs are in turn optimized to help them achieve that. Making the quality as good as possible while being able to render 30/60/240 frames per second. Videogames do *a lot* of shortcuts and clever tricks do make the image look great with minimal computing. Like normal maps, baking in lighting, a plethora of shaders, lots of post-processing, etc. - Professional 3D rendering engines are optimized for quality and realism. As in, putting an actual light in the scene, and calculating how the rays will bounce off the objects and into the camera. Those kinds of calculations take more time, but produce much better results and are more flexible. But when it's all said and done, the rendering calculations themselves can be processed by the CPU or GPU cores, depending on which will do the task faster/cheaper/more energy efficient with the software in question. You can try it for yourself with Blender. Take any scene, and render it out using Cycles renderer. First using a GPU and then a CPU to see how they'll perform. A GPU will render one sector at a time, but very fast, whereas a CPU will render multiple sectors at once (with each of its physical cores), but each sector will take longer to render. But that's an ELI5 version, 3D rendering is one of the most mathematically complex subjects in computer science and I'm too uneducated to dive into more details.",
"Blender does use GPU to speed up its Cycles rendering engine. Larger scenes may cap out the Vram on the GPU so you may have to use CPU for rendering.",
"When images are rendered using the CPU that's called a software renderer as opposed to a hardware renderer of a GPU, for the most part, GPUs can render images more efficiently than CPUs can, the reason that those benchmarks use software renderers are because a software renderer is very taxing on the CPU and those programs are benchmarks/stress tests.",
"> Why are games rendered with a GPU while Blender, Cinebench and other programs use the CPU to render high quality 3d imagery? Both CPU and GPU can render either things. Many older games had a \"Software render\" option ( which uses only the cpu ), while programs like Blender/Adobe/etc. hava an option to use your GPU instead. Even a cheap GPU is much faster than most CPUs at both tasks. So why the difference? well ... Games use the GPU by default because most CPUs would be simply too slow to keep up with real-time rendering required by most videogames. Software like Blender use the CPU by default because rendering time is not much of an issue and, more importantly, not all GPUs are compatible with every one of these programs. Another big factor is that anything less than \"perfectly stable\" GPU could cause the whole program to crash and make you to lose many hours of work.",
"Well all those are truly simplified answers. If in plain words - CPU oriented towards quality , while GPU’s primary focus is speed. That doesn’t mean that GPU will be bad looking and rendering by CPU is always beautiful. It all goes down to artists and their techniques for each approach to make best out of it. Now regarding why some are rendering buckets (squares) while others use progressive method (shows full picture in bad quality, noisy and slowly refining it) - those are usually for different usage. In fact in main render engines like Arnold, you can choose how you want your image to be rendered. - Buckets (squares) are usually used for still images and in fact you can decide how to distribute them - spiral from center or in lines from top. Benefits of this approach is that you can immediately see the final quality on rendered areas - Progressive rendering (from noisy to clean image) usually utilized for sequences (a number of images) for animation. Especially when it requires further post production. Benefits of this approach is that you can get your entire sequence (like few hundred frames) in few minutes - it will be noisy and low quality but it will be enough to start further post production. Like compositing or editing. And while you do you post production - your rendered sequence (3d animation) will be refined better and better. What’s cool is that these days some render emgines allow you to render images in low quality (but good enough for understanding whether changes needed) and even after you stopped render - you can actually come back and resume your render from where you stopped without the need of starting from the beginning.",
"And now, a thread with 60,000 different nine-paragraph wrong answers, 59,000 of which start with the word \"Actually.\"",
"~~Blender~~ Cycles can be configured to render from the center outwards, or from a side to the other side, and in many other patterns. It also can be configured to render a \"crappy first image then refine it\", and that is called progressive rendering. Cycles can utilize either the CPU or GPU for the task. Rendering with the GPU is usually much faster, but either partially does or doesn't support some effects.",
"GPUs are about doing simple things, many times, very fast. A GPU is a compromise that works great when speed is more important than precision. They take shortcuts and have limitations. Games employ lots of tricks that only work in very specific scenarios, and not in general, and make the whole thing work by avoiding the situations in which the illusion would break. Things like Blender on the other hand aim for precision and flexibility above speed. Take for instance that the human body isn't [completely opaque]( URL_1 ). A renderer like Blender can be told this, and [simulate this effect]( URL_0 ). A game, 99% of the time just won't bother at all, or fake the effect by using a custom texture in the one scene where it's needed. Something like Blender on the other hand can do it consistently, and correctly for any kind of lighting. Doing these kinds of highly complex and flexible calculations has been above the abilities of most GPUs for a long time, but thanks to new hardware having features like CUDA and RTX, programs like Blender are starting to take advantage of 3D acceleration for some of the work."
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f1pkqj | how do headphones work? how do they generate sound from a device through a wire into your ears? | Technology | explainlikeimfive | {
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"it's the interaction between the electric current in the wire and a permanent magnet that generates the sound waves. The current generates a variable magnetic field around the wire, causing it to move/vibrate in the magnetic field of the permanent magnet depending on current direction/amplitude. The vibrations will then propagate through the air to your eardrum and so on. it's the same basic concept to a \"normal\" speaker (unlike electro static or plasma speakers). & #x200B; edit: this video seems to cover the basics quite well: [ URL_0 ]( URL_0 )",
"Answer: Sound is literally vibrating air getting into your ear. A headphone contains a little metallic drum. The drum is in contact with an electromagnet. The sound signal in the wire drives the electromagnet, which makes the drum vibrate, which makes the air vibrate into your ear. Why does the electromagnet vibrate: the sound signal is wavy. It gets into a tiny electric coil. This makes a varying magnetic field. There is a magnet inside the coil, attached to the drum. The varying magnetic field exerts a force into the magnet and makes it move back and forth."
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f1sl1c | 16bit v. 32bit v. 64bit operating systems | What's the difference, and will we one day have 128bit systems? | Technology | explainlikeimfive | {
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"The bits typically refer to the size of registers in a CPU. Registers are like buckets inside a CPU that hold an integer value. 8-bit computers could store an 8-bit value (0-255) in a register, 16-bit CPUs operated on 16-bits at a time (0-65535), 64 bit computers have 64-bit registers. Newer x86 CPUs already have (vector) registers that are 128, 256 or 512-bits so we're beyond 128-bits already, but the CPU itself isn't considered a 128-bit processor. There's a bit of fuzziness as some CPUs (x86) are backwards compatible, so a 64-bit x86 CPU can still use 64, 32, 16 and 8-bit registers. 8-bit computers could still do 64-bit math using carry operations. 8-bit CPUs were things like the 6502 (Super Nintendo, Commodore 64, Atari 2600). Intel 8086 (IBM PC) were 16-bit, Motorola 68000 (original Macintosh, Amiga) were mixed 16/32, ARM is 32-bit (but can do 16/8 as well), etc.",
"To really ELIF it: in a computer, data is passed around in big pipes. Some pipes are 16, some are 32, some are 64 bits wide. One of the main reasons pipes have gotten bigger over the years is the bigger the pipes are, the more memory you can add to a computer. I can't think of a way to ELIF that, but it has to do with the fact that you need more information to keep track of all the RAM out there. (The address space is a lot larger, so you need more information to find where your data is being stored in memory.) 128 may come some day but it's a long way off because each time you double the size of the pipes, you can store way, way more memory."
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f1ug3p | Why are upload speeds always lower than download speeds? | Technology | explainlikeimfive | {
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"text": [
"There is only so much bandwidth that any connection can provide, and it has to be allocated between uploads and downloads. Since most people download _far_ more than they upload, it makes sense to dedicate more resources to the tasks that are done more often. Think of it like a highway with eight lanes total. You would think the most logical division is to have four lanes in one direction, and four lanes in the other. However, if you discover that 80% of the traffic only travels in one direction, then it would make more sense to have 6 of those lanes dedicated to that direction; the highway only has so much capacity, so you allocate it to where it will be used most effectively.",
"Because most people don't need upload as much and it's easier advertising a 250/50 connection than 150/150. In theory a 50/250 connection would be possible but not very useful for most"
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f1vj85 | 3D printing | Technology | explainlikeimfive | {
"a_id": [
"fh8o1go",
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"text": [
"The problem is that 3d printing is a concept. Every 3d printer will have a different answer to these questions. It's like asking what food tastes like. Each food tastes different. Some 3d printing is by drops of a liquid that harden immediately. This is cheap but produces crude results. Some extrude a paste (like concrete) that hardens slowly but maintains its shape. Some are built up by using a layer of liquid material that hardens when zapped by something at a specific point. The machine basically draws what it is printing on the material. That part hardens and the rest drains off leaving only the solid part.",
"It's effectively a hot glue gun on a robotic arm. It moves the extruder (the nozzle) in computer-controller paths to add material layer by layer slowly building the object over time. That material is usually a PLA, ABS, or Nylon plastic, though there are printers that can work with metal or even cement. There's generally a spool of plastic filament somewhere in or on the machine. Most that I've seen have bays for it on the back of the machine. The filament is fed from the spindle through tubes to the extruder, which melts the filament and deposits it. It's not solid right away, since it's extruding molten plastic. You generally want to wait ~10 minutes for the plastic to properly set before removing it from the machine, or else you risk the plastic still being slightly soft and deforming when you touch it. The plastic sticks because it's sticky. Just like a hot glue gun."
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f1vo8e | How did insane conspiracies spread before the Internet? | How did absurd and ridiculous theories spread before the days of the Internet or Social Media? | Technology | explainlikeimfive | {
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"text": [
"People rote pamphlets and passed them out. People are still doing this. People wrote books, e.g. saying Space Aliens built the Pyramids, and sold a bunch of copies.",
"The same way witches were called witches and murdered, through gossip, then in the modern era through stupid pseudo science supported by false photos and false articles."
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f207eg | Why do professional Arcade fighter players use arcade sticks instead of Game pads? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"The main benefit is the accuracy of the stick. Your thumb pad is prone to accuracy issues that are huge in fighting games, because an inexact input completely changes what you're going to do.",
"They don't all use sticks. Many use pads or stickless controllers like the Hitbox. Sticks are nice because they allow you to more easily input what you want precisely. Pads kind of vary in this area. The button layout is also good for fighter that involve things like multi-button inputs or pianoing (rapidly pressing multiple keys), and double tapping buttons to get more leniency on tricky input windows. Stickless controllers offer the same benefits of buttons and trade some of the preciseness of the stick inputs with being able to do directional inputs more quickly. They are especially good for half and full circle inputs, especially if the game has lenient inputs. But I'm missing one of the biggest reasons: legacy. Competitive fighting game play largely sprung out of the arcade scene in Japan. People there would generally go to an arcade and learn on the sticks on those cabinets. If that's how you learn, then you're going to be most comfortable playing a tournament using the same type of controller. At this point the general consensus among fighting game players is to find what you like the most or are most comfortable with and use that. If you learn to use it well, then you can even [beat top 8 players with a steering wheel]( URL_0 ).",
"You can put your whole hand with all 4 fingers (5 if the stick has thumb buttons) on buttons at once. If you need to hit 3 buttons in a precise order, what's easier: hitting them with 3 different fingers that are already positioned over them, or with your thumb, one after another, moving in between each press?"
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f2254k | Why can videos be recorded smoothly and played back almost instantly but when it's rendered it takes a lot longer? | Technology | explainlikeimfive | {
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"text": [
"When you're recording something, you're taking something that's physically in front of you and recording what color intensities are where on the sensor. When you're playing something you're taking a list of color intensities and displaying them. Rendering is different. It's part of the animation process and doesn't involve a physical thing like recording. You're doing a bunch of math to figure out the color intensities instead of just looking at it. Take lighting as an example. On a camera you have a physical light source that's sending out light waves that reflect off an object and go into the camera. In rendering, you know where a light source is. You have to do a bunch of math to figure out how the light waves would actually travel. Then you have to do even more math to figure out how those light waves interact with the object. Then you need to figure out how they travel and how they would interact with a real camera. When something moves, it doesn't physically move, instead you're doing a bunch of math to figure out how it would really move."
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f22cwp | What makes that last 1% on your phone battery so much stronger than the rest? | Technology | explainlikeimfive | {
"a_id": [
"fh9xkf6"
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"text": [
"It’s much like your car being on “E” for 20 miles. It’s just a warning sign and they give you plenty of time to make up for your mistake of not paying attention."
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f242uh | If almost all camera lenses are circular, then why are almost all pictures rectangular? | Technology | explainlikeimfive | {
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"text": [
"Cameras work by shining light on something that changes color forever when the light hits it. While the lens may be a circle, the thing the light hits is a rectangle. When cameras first became popular, the thing the light hit was a roll of film. It was essentially one long, thin sheet, rolled up onto a spool. The camera would cover all but a small section of the roll of film, and allow the light to hit that. Because of the way it was shaped, the piece left uncovered was a rectangle, because you could fit more rectangles on a roll of film, which fit more pictures, so it cost less per roll of film.",
"Given the laws of optics it's much easier to design a circular lens than a rectangular one. Both are possible, but rectangular lenses need to be cut from from circular ones so more cost and more error. So it's about manufacturing. However image detection is accomplished with a rectangular sensor, it's traditionally made that way because it's easier to make, package, and rectangular images are the norm. So it doesn't matter that the image falling on the detector is circular, because the detector will only detect part of it, a rectangular part. Edit: for more details, please see URL_0 And English"
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f25140 | I know kernel is important and critical part of Android. But what exactly is it? How does it work? Why are there so many different version of it. And if Android have it, do iOS have as well? | Technology | explainlikeimfive | {
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"text": [
"If you think of a computer as a company where programs are employees doing many different things, the Kernel would be a high ranking manager. It's most important job are assigning processing time slots to the many different programs running on the computer, assigning memory space to programs, giving programs access to external devices like thumb drives and also controlling which programs get to use what kind of functionality and data on the computer. For example, if you give an Android app some sort of permission, this tells the kernel that the app is allowed to make calls etc. If an app does not have the permission, but tries to make a phone call, the kernel will just refuse access to the part of Android that handles phone calls. It's a safe bet that any kind computer that handles many different things at once has a kernel. Even the ones built into household electronics, like smart lightbulbs will have a rudimentary kernel in them.",
"Your apps don’t actually know how to do anything on their own. They don’t know how to add number together. They don’t know how to store stuff. They don’t know how to connect to the internet. What they do know is how to ask the kernel do all those things for it. The kernel knows how to talk to apps. The kernel knows how to operate the CPU to add numbers. The kernel knows how to read and change memory. The kernel knows how to operate the wifi. The reason is that app developers don’t really want to waste time dealing with all the many different kinds of CPU, memory, internet hardware, etc. They just want to make their app work. So they leave all that stuff to the people who code stuff included in the kernel. All they have to do is ask the kernel, and they stop worrying about how it all actually gets done. The kernel also gets to do stuff like change stuff related to the hardware, and figure out which app gets to use whatever at whatever time. To answer the rest of the questions: - Where are there so many different versions of it? Because the list of stuff it needs to support keeps growing. Also if you really wanted to do horrible things to a machine, if you somehow exploited the kernel, you'd be able to start doing the worst of the worst bad stuff. So they have to fix it to stop the bad people from stealing everything. -if Android have it, do iOS have as well? Android, iOS, Linux, Windows, and pretty much every other modern operating system have their own kernels. Though Android and Linux have the source code for their kernels published, so you could make changes if you wanted. Android actually started by modifying a linux kernel.",
"It's just a low level part of the operating system. It handles things like scheduling which processes run at which times. Operating systems, kernels included, are updated to improve performance, fix bugs, and so on. I would expect every operating system to have portions we could call a kernel, including iOS. More details here: [ URL_1 ]( URL_0 )"
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f28d41 | How do telescopes detect planets and other space objects that are billions of light-years away? | Technology | explainlikeimfive | {
"a_id": [
"fhavo49",
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"text": [
"We cannot detect planets that are billions of lightyears away. The only things we can see at that distance are whole galaxies, and those only as points of light. The diameter of a galaxy is trillions of times larger than the diameter of a planet. The exoplanets we *do* see are from nearby stars, only a few year lightyears away. And for the most part we don't even \"see\" them really, we just detect their effects on stars.",
"Telescopes can't actually *see* the planets outside our solar system - they're too distant and dark. What they can do is detect the planet by various methods, for example when the planet crosses in front of its star, the star's brightness is slightly reduced. Also, the farthest discovered planet is \"only\" 27,000 light years away, not billions of light years.",
"There are several methods of detecting planets round other stars, you can observe the star and if the brightness of the star dims on regular occasions to the same degree you can work out that a planet may be passing between the observer and the star and how long it dims for and the degree it dims you can work out things like the size and distance of the planet, for large planets you can also see if the gravitational pull of the planet makes the star wobble. URL_0",
"We typically detect exoplanets by seeing a “wobble” in the star that they orbit. Planets are massive enough to drag their star around slightly with their gravity as they circle it, and we can see that periodic wobbling and deduce the planet’s existence. We don’t generally see the planets themselves."
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f2fatw | why do printers need all their colors to print something even if the requested print is just black and white? | Technology | explainlikeimfive | {
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"fhc50hu",
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"text": [
"Almost all inkjet and laser printers put [Machine Identification Code]( URL_0 ) dots on their printed pages. This allows the page to be associated with the printer that produced it, which can be helpful for law enforcement. As these dots are color, they require color ink to be present to print.",
"Because printer ink is more expensive than gold and printer manufacturers want you to burn through ink for pointless reasons to get you to buy more ink.",
"The real reason is because printers use color to make the black blacker and richer. If you force the printer to grayscale, it disables this, but you'll notice your text is not as crisp and dark. I'm not sure of the exact color science behind it, but that's basically the difference if you print with high quality settings (which are on by default) or you switch the printer to grayscale. You can also set the quality setting to \"normal\" or \"draft\" which will use less ink repsectively, but also cause your text to appear less bold.",
"They don’t :) the manufacturers force you to buy cartridges of the most expensive liquid on the planet :)",
"Is your requested print B & W? Even though an image file might appear B & W its colour profile might be in sRGB or AdobeRGB and then again a .tiff might print slightly different to a .jpg and we are not even printing yet. Its black magic. What are you printing on satin, matte, glossy, canvas, silk? Each media will have to be profiled to print B & W but that does not mean that a generic matte profile will give you a B & W printed image sometimes they need to be tweaked most likely in a rip software. So in answer to your question you need colours to be able to print in B & W."
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f2he8u | How does taping one side of a gaming disc make the system read the disc? | My fiance and I have a Playstation 2, and some of the games were struggling to read because they have the purple backing. He saw that if you place 2 pieces of masking tape on the side with the title on it, the system reads the disc. Scientifically, how does this make the system read the disc all of a sudden? I'm totally stumped by this. | Technology | explainlikeimfive | {
"a_id": [
"fhes6gj"
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"text": [
"Optical discs work by a laser shining through the dye, being refracted in tiny pits in the plastic and being reflected back by a super thin reflective film near the \"title\" side of the disc, back to a light sensor. The film is so ridiculously thin that it typically isn't entirely opaque, so some laser light leaks through to the title side and through it rather than reflecting back. Kind of like if you took the backing off of a mirror, it wouldn't work very well as a mirror. In cases where the laser isn't performing very well, having a label or tape on the disc *may* give it that little bit of help it needs by catching that light and scattering it back."
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f2heiw | how do they make intricate objects with glass (and other things)? | Like the really intricately shaped glass things and really small glass objects, surely they can’t use glass blowing. And for other things, how do they make microscopic things like the syringes used to remove nuclei from cells etc | Technology | explainlikeimfive | {
"a_id": [
"fhcwhfx"
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"text": [
"They take glass components that are melted to something called working and softening temperatures. These allow the melt to be soft enough to mold with a rod and yet viscous enough to resist flowing much like honey just a lot slower moving. Things like a rose can be made by using pliars to physically pull pedals from a glass blob on the end of a rod. It is then dipped back into the melted batch to gain an extra layer to pull more petals. Once the rose pedals are made a stem is pulled from the melt extended and then the cooling pedals are attached to the stem. It then sits in something called a lehr to cool slowly. Basically, most shapes are uniquely crafted layer by layer and is usually reheated multiple times over several hours to shape it appropriately. Glass blowing only adds to the complexity of it and doesnt allow for much time to reheat."
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f2i2fz | How do wildlife videographers achieve the shots we see in documentaries? | I appreciate that it's all done with high quality cameras, coupled with patience and timing, but some of the shots you see in documentaries are mind-blowing! Common sights like tracking animals through high grass, yet still remaining completely in focus. How do these professionals achieve such amazing shots and are there any techniques or equipment they use in particular? | Technology | explainlikeimfive | {
"a_id": [
"fhcol1w",
"fhcorjb",
"fhcomsc",
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"text": [
"You underestimate how good these photographers are. They deserve all the awards they get. They're just that good. Also, really REALLY long lenses.",
"1. Very large zoom lens 2. Cameras on motion control 3. Staged shots in the wild or places like zoos and even stages 4. Lots and lots of hours of footage that is edited down to seconds",
"Time, time, patience and more time. While they have honed their skills with their camera so that they are ready for the shot when it happens, they spend a \\_crazy\\_ number of hours working to get \"that shot\". The \"techniques\" range from sitting around all day for weeks and months on end to get acclimated tot he environment, to get the animals accustomed to their presence and so on. Then....they take a TON of shots. It's a 1000 to 1 kinda game where 999 go into the bin and 1 gets published. And...that's being optimistic.",
"semi-professional photographer here. Lets go: Reason 1: quality of camera's lens / stabilising and focusing system (that is able to track the target despite it being behind something for short amounts of time. Consumer grade cameras can already do it (i.e. the Canon 7d Mk2 or 1DS DSLRs), but TV grade cameras are way way superior to even those, both in programming, and optics used (one of reasons why proper TV studio camera can cost quarter of million USD easily, with most of that being the cost of lens...) Reason 2: Operator's experience. Even with lower grade equipment, there is tons of tricks you can use, like prefocusing the camera at given focal plane (i.e. focusing for given distance), then switching over to manual focus only and not changing the focus. Then, you wait for that 1 in 1000 chance of animal walking where you want it to walk (to). Sometimes using food bait (like seeds for birds if you want to film/photo them on the ground). Reason 3. Taking LOTS (And I mean LOTS) of concurrent shots (which is where, again, equipment helps a lot. With top level DSLR you can go ~16-20 frames/second burst.) - for flying birds you can get a thousand shots easily, then you choose the best. I went through 250 GB worth of storage in one day more than once, just for photos."
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f2iguc | Can/how machine learning algorithms understand text stories? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"It’s all math. ML can parse text stories and classify the data based on training sets. It can even use the resulting matrices to generate summaries, semantic clusters of meaning or secondary legible texts that are of a similar style. But the algorithms aren’t understanding anything, they’re just sorting and clustering the encoded data based on a pre-programmed training set of similar texts. Of course, it could be argued that this is all humans are doing too....",
"Machine learning algorithms don't understand text, but given enough training data they can learn to do simple things with text, like categorize by topic, or summarize. However, when it comes to deeper understanding, it's easy to trip up algorithms. Here's an example of the type of thing that trips up computers. In the following two sentences, who does \"they\" refer to? * The city councilmen refused the demonstrators a permit because they feared violence. * The city councilmen refused the demonstrators a permit because they advocated violence. Humans only get the correct answer due to prior knowledge and experience. There are no machine learning algorithms today that have enough prior knowledge and experience baked into them to get questions like this correct. \\[[Source]( URL_0 )\\]"
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f2j23c | Why do modern smartphones use multiple cameras instead of one large sensor? | Don't larger sensors reduce noise and have higher image quality? Why do they just add multiple tiny cameras that can't capture any decent photo in a place that isn't brightly lit? | Technology | explainlikeimfive | {
"a_id": [
"fhcuxwr"
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"text": [
"Cameras can only really zoom by moving their lenses. With 1 stationary lense, all you do when you zoom is crop the picture. If you use multiple lenses that are predone for different zoom levels, as you zoom, you can switch lenses to keep actual detail from being lost too much."
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f2k3uk | What is DirectX and how does it work? | Technology | explainlikeimfive | {
"a_id": [
"fhd3gs6",
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"text": [
"It's a graphics API (Application Program Interface) that gives programs access to graphics hardware. Somewhat simplified: Program (game or similar) - > Graphics API - > operating system/graphics driver - > graphics hardware since the graphics driver and hardware is vendor and even device specific there needs to be a standardized way to access it. That is done by a graphics API like DirectX, OpenGL or Vulkan.",
"instead of game designers learning how to program for specific hardware (graphics cards) or deal with OS nuances, the game designers just have to learn how to use the API to do what they want. the API then handles the translation into driver level commands to the hardware or OS level commands to the OS and the game designer doesn't have to care if the target system is gonna run on amd gpu, intel gpu, nvidia gpu or windows OS, macOS, or linux (as long as the API supports them all)."
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f2l86n | What is Aliasing? | Basically I was wondering what is aliasing and how does changing the sampling rate of the signal effect aliasing? | Technology | explainlikeimfive | {
"a_id": [
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"I'm not an expert on this, but I'll try to explain it. Aliasing is when you misidentify a signal and get distortion. When your sample rate is to low, you don't get a complete picture of what the signal looks like. Let's look at a sine wave to make it easy. You need to measure the signal several time per cycle to be able to identify it (i believe you need at least two points). If you don't measure fast enough, you can miss the peak (or even several) and catch other parts of the wave thinking it's before a peak. [Here's what that looks like]( URL_0 ). The end result in this case is that the frequency you see is slower than what you actually have. There's a special case where your sample frequency is the exact same as the signal frequency. You always see the same part of the wave so it doesn't actually look like there's a signal at all.",
"Most simply, aliasing is when your sampling rate (+filter) makes a higher frequency masquerade as a lower frequency. As you might know, you need at least 2+ samples per cycle to accurately capture a wave. You can think about this in terms of weather. Say you were trying to figure out the weather in Ohio the 1800s, and all you had were a farmer's diaries. If the farmer only ever recorded the weather once per year (1 sample per cycle), on June 21st every year, it would give the impression that Ohio is just warm all-year round: 1. June 21st, 1850: 80 degrees 2. June 21st, 1851: 80 degrees 3. June 21st, 1852 (and so on): 80 degrees Connect the dots, and you have a straight line at 80 degrees---you have no evidence that there is a cold winter at all, so you haven't accurately captured this weather cycle. In contrast, if the farmer tells us about the weather on June 21st and also December 21st of every year, you at least have a coarse idea of the fact that Ohio weather goes up and down over the course of a year. Preferably you would have more samples than that, partially to avoid consistently sampling at the midpoint (spring and fall, which would be pretty similar, and so you would guess that the weather is always in the mid 50s and you wouldn't know that Ohio gets both hot and cold), and partially to have a more detailed picture of the cycle. So that's basic sampling constraints, which you might already know. Aliasing is when you don't hit that 2+ samples per cycle criterion and you get a different wave when you connect all the samples. This can happen like with the \"always summer\" example from above, but that's just a flat line, so it's not quite as bad; but you end up getting a different wave if you have anything above/below exactly 1 sample per cycle, and also below 2+. So picture this: the farmer for some reason only writes down the weather every 9 months. This is more than one sample per cycle (year), but less than 2+. 1. June 21st, 1850. 80 degrees 2. March 21st, 1851. 40 degrees. 3. December 21st, 1851. 0 degrees. 4. September 21st, 1852. 40 degrees. 5. June 21st, 1853. 80 degrees. Woohoo! We hit a full cycle! Now we know that the weather in Ohio repeats every 3 years. Except... you know, as a resident of Earth, that it doesn't. This is aliasing---a cycle that is actually 1 year long is showing up in your recording as 3 years long (a higher frequency is being recorded as if it were a lower frequency). So the moral of the story is that if you know you're trying to capture a cycle that lasts one year (one minute, one second, one millisecond, whatever unit of time), you need to take a sample at least TWICE in that time period. Anything less will give you a false wave frequency. Now obviously when you are making a sound recording, even if you decide that you only care about frequencies up to 5,000 Hz (thus requiring a 10,000+ Hz sampling rate), the world still HAS frequencies above that. So microphones come with anti-aliasing filters that block frequencies above the ones you're interested in. However, filters aren't perfect and can't make a hard line between \"yes, 5,000 is okay, but 5,000.1 is not\"; instead, they have a gentle slope of blocking that lets through frequencies that close to your limit but ultimately blocks the really high ones. So in reality if you want to capture up to 5,000 Hz accurately, you'll probably want a sampling rate closer to 11,000 Hz just to account for that little squish zone."
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f2lyxy | What does it mean when people say "The internet should be a public utility"? | Technology | explainlikeimfive | {
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"It would mean that internet access is publicly funded (taxes), and free for anyone to use. Other examples of public utilities are roads, street lights, and police."
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f2myoc | What is that weird light trail artifact in old video tape footage | Whenever I saw videotape footage from the 80s or earlier, there would be this "light trail" artifact in some of the shots. For example, when there would be a bright light (e.g. explosion or stage light) in the shot and the camera would pan to another part of the set, there would be this line of brief discoloration that trailed where the light bright was. What is it called and what causes that? | Technology | explainlikeimfive | {
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"Old video cameras would project an image onto a photosensitive plate and then used a cathode ray tube to scan the image. The plate held the image briefly after being exposed to light, kind of how heat sensitive paint or material can change color when touched, or a mug will show an image when hot liquid is poured inside of it. The outline of a hand or the image on the mug doesn't disappear immediately when the heat source is removed, but has to wait for the material to cool back down to its base temperature. The photosensitive plate in old cameras worked the same way, but with light. The image would persist for a fraction of a second, long enough to be scanned, but faded and changed as the light and shadow in the shot changed. The brighter the light, the longer it would take to fade, and when a light source was significantly brighter than the rest of the scene -- like a stage light or an explosion -- you would get those light trails as that part of the plate took longer to fade back to its normal sensitivity. This stopped being a problem as more cameras moved to using charged-couple device (CCD) sensors in the 1980s."
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f2rcaq | Why are standard world maps considered to be inaccurate? | I remember being told this in high school and being totally confused. My teacher told us that a standard map, or even a globe, is inaccurate. She explained why but I didn’t understand. Why is this? | Technology | explainlikeimfive | {
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"A globe is definitely accurate. The standard maps are inaccurate because the world is round, and maps are flat. There's no way to project a spherical map on a flat surface without stretching or tearing parts of the map. In the former case you get maps like the [Mercator projection]( URL_1 ) which makes areas closer to the poles huge, and in the latter case you get odd things like [this]( URL_0 ).",
"I hope this is allowed. [The West Wing]( URL_0 ) had a great, informative bit about why maps are not always correct. I believe the visuals are especially helpful",
"Remove an orange peel all in one piece and lay it flat. Points on the surface of the peel are the same size and distance from each other as when they were on the sphere. But then stretch out the peel to make it rectangle (like a map). To do that, you have to stretch the peel. Points get farther from each other. Imagine doing that the surface of the Earth. Realize that where you choose to do the stretching has an impact on things' relative size and relationship to each other. Or do it in reverse. Take a sheet of paper draw a map on it, try to wrap it around a sphere-like object. Notice all the ways it doesn't quite fit. Those are inaccuracies.",
"I'm not sure why they would say a globe is inaccurate, but normal two dimensional maps become more inaccurate the further away from the equator you look because it's taking an area much smaller than the equator and stretching it out to be as wide on the paper as the equator itself.",
"You can't take a round map and make it a rectangle without squishing or stretching parts. This is fine, it's not evil that it is that way. But it is worth knowing about, it's pretty obvious that \"we\" picked the standard map to be the one that centers on the western world and enhances it's size. North America grows, Africa shrinks, Alaska gets to be bigger than India, europe gets to be giant, Etc. Like no one sat down and said \"ha ha, lets make white dominated countries the biggest!\" but it sort of did work out that way, the standard map is really focused on making america and europe bigger and more central to the map and putting some other countries into the \"it's fine if this ends up distorted, who cares\" bucket. And it's worth thinking about how that could be different and the map we happen to use is just one possible map.",
"All flat maps are inaccurate, there is no way to transform the surface of a sphere into two dimensions without distorting, size, shape, or relative direction. This is old news, they pointed this out to us in grade school. Every now and then, people get political over it. Developed countries, like those in North American and Europe, tend to be in the higher latitudes the popular Mercator projection makes too large, while less developed countries tend to be more tropical and appear smaller by comparison. Some people think this perpetuates bias or is even a part of some grand conspiracy."
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f2sqh2 | Why do some texts arrive almost immediately,while others take hours,or even days? | Technology | explainlikeimfive | {
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"Are you always connected to cellular or wifi? If you are out of cellular data and not connected to a wifi network, it won't come through until you are. Or the person sending it was ghosting you and didn't want to admit to it.",
"The times they come in quickly are your friends and people who like you. When they take hours or days it means shes not interested in you."
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f2sxb8 | how do gesture recognition sensors work? | In new phones and other kinds of technology, there are sensors (I think radar) inside of the objects that can detect what gesture you're making. I understand that they recognize the gesture based on prior training and basically matching a picture to another, but I was just wondering if there were a lot of bunched sensors that are together that tell the distance of each spot of your hand or something like that. | Technology | explainlikeimfive | {
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"Your guess is basically right. Relating specifically to the Pixel 4 anyways. There is a small chip the size of a coin (nickel used in the article) which is studded with a bunch of tiny little sensors that emit electromagnetic waves to detect motion just like mini-radar. measurements are taken from each of the sensors and depending on things like speed, signal intensity and the order in which they \"fire\" determines which gesture was made and thus what reaction to present. & #x200B; [ URL_0 ]( URL_0 )"
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f2uluk | what is reverse osmosis and why is it important for consumable water? | Technology | explainlikeimfive | {
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"Water resources engineer here. It’s a filtering process that can remove dissolved compounds such as salt (desalination plants) that requires quite a bit of water pressure and has a higher ratio waste stream (high ratio of incoming water doesn’t end up as treated water) so is more expensive than most other water treatment methods.",
"Pressurize sea water (or other non-pure water) through a filter membrane. The membrane has pores so small than minerals and salt ions can’t pass through. Microbes, being very much larger than ions, will definitely be removed. Only water molecules are small enough to pass through the membrane, everything else is trapped behind the membrane. Multiple layers of membranes in sequence can produce very pure water. Reverse osmosis is expansive compared to other sources of water (groundwater from aquifers, reservoirs etc). It also takes a large input of water to produce a small amount of pure water, the remaining is discarded as brine. Most home “reverse-osmosis” kits are scams, people don’t know the difference between RO membranes and cheap carbon filters."
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f2xtx2 | They say my phone has more computing power than the computers that got Apollo 11 to the moon. Does that mean, theoretically, my iPhone could orchestrate a moon landing from take off to touchdown? | Technology | explainlikeimfive | {
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"With the right software that is true. In fact people have made simulators of the actual Apollo Guidance Computer which will allow your iPhone to not only orchestrate a moon landing but doing so by simulating the original computer. The statement is a bit outdated now. The updated statement is that your phone charger have more computing power then the computers that got Apollo 11 to the moon.",
"Theoretically your phone, or possibly [even just its charger]( URL_0 ), would in theory be able to land something on the moon - your phone would be able to do it without even noticing the effort. HOWEVER, there are important differences and caveats; The Apollo computers were specialised hardware with real-time operating systems - that means they were designed, built, and programmed in such a way that if you need to fire a rocket for EXACTLY 152 milliseconds, the computer can do that absolutely bang on every time even though it's a million times slower than your iPhone. Your iPhone, as it is out of the box with its non-realtime operating system, can TRY to do that, but because the OS doesn't guarantee that sort of real-time performance, you might fire the rocket for 152ms or, if at that exact moment an app decides to pop up and use a load of processing power, the rocket might stay on for a whole second... or if the app crashed the phone while the rocket was lit it might stay lit for 5 minutes while a little coloured whirly thing went round and you smashed into the moon at a thousand miles per hour. This is the difference between operating systems like you find in your phone or laptop, and embedded systems that have to control real-world things that might hurt people or burn your toast. Now, *theoretically*, it's possible to create an OS like that for any system, but Apple like to lock their shit down so good luck with that one. The various other *smaller* computers inside your phone (most of which are also capable of landing on the moon) which control things like the various sensors, the cellular radio, wifi, bluetooth, battery charging, etc. etc. etc. are more realtime and might be a reasonable prospect but are often somewhat single-purpose, so don't have enough IO (inputs and outputs) to do the job - in short, not enough legs on the chip to wire all the things to.",
"Yes. You have more number calculating power than there's was on board at the time. They didn't need or able to have that much computer power. They weren't going to a random place that needed real-time calculations. Those were done months ahead of time on Earth and needed to be loaded in and the burn sequences executed by the computer. Your cell phone has 1000x capabilities of your high school TI-85 calculator. Which is already a complex computer.",
"Not only could your phone guide a rocket to the moon, it could also [simulate the rocket, the moon, and the Earth and draw a real-time 3D view of them]( URL_0 ). In fact, the math for orbital mechanics is surprisingly simple. Spacecraft basically fly in ovals around planets, and you can use [high-school geometry to chart a pretty accurate course]( URL_1 ) that's good enough for most space missions. Space travel takes so long you could probably even do the math by hand.",
"The computers that were used for the Apollo program had one task and one task only to land on the moon, the Iphone is running lots of things just to keep the phone operating and linked to the network, however given the right programming yes your phone could handle the processing of the information for a moon landing.",
"A calculator from the 1980's is more powerful. Your iPhone is orders of magnitude more powerful than anything even conceivable in 1969. Yes, it could handle the moon landing.",
"A modern smartphone can do 10 billion mathematical operations per second. The Apollo guidance computer did something like 32 mathematical operations per second.",
"Even those electronic birthday cards that play a song when you open them have more processing power than the Apollo 11 ship... so yes",
"Yes and No. Yes, your phone has plenty of arithmetic speed. You could definitely do all the multiplies, and then some. No, your phone is full of gigantic blobs of code that keep it from performing like an AGC does. For the full story read Don Eyles memoir [Sunburst and Luminary]( URL_0 ). Each instruction in those AGC programs was individually written by a smart engineer, and many hours were spent making them more compact and efficient. A custom interpreter was used when code didn't have to be perfectly fast. There is no practical way to run your own machine code on a smartphone, all the operating system software is built to prevent the kind of high performance computing done in early computers. Manufacturers care a lot more about enforcing license clauses than getting the right answer in the minimum number of instructions.",
"I don't think there's anything compute heavy about sending something to space, orbit, or even another planet. Once the scientists figure out the maths it doesn't take a lot of computing power to actually solve the math problems and keep yourself going in the right direction. I'm not a rocket scientist but that seems like the simplest part of the equation by a long shot.",
"That depends if it will be going in to space. A consumer device isn’t hardened for EM and other events that it isn’t exposed to at significant levels on earth but would be major risks in space. Part of the reason why on board computers from that era seem low powered was precisely so they could be hardened. This makes them far less prone to error or failure. Which is critical.",
"Yes, computing power of such device would only require few from few hundreds responsible for that landing at that time. Indian and polish universities did things like that (forgive me other countries but did not follow a topic for a while). Basically they connected with sources sending an ancual rocket to space and then separating and completening the landing of stuff like andruino board etc.",
"Not really. That statement means that in terms of pure computational power - literally how much maths can be done in a certain time, your iPhone can do more and do it faster. But keep in mind that you're asking one computer to do all the work by itself (well, usually 2 to 8, because it actually had multiple computers (processors) running at the same time. NASA used many many computers simultaneously to do different jobs, and each had its own processor that it didn't have to share. The computers each had a specific function to perform, and didn't have to wait to process the data. There's no question your iPhone is more powerful than all those individual computers and even all of them combined. But there is the question is it able to process the data correctly. If your iPhone has a 4 processorvCPU and you need to execute 5 pieces of data simultaneously, you're out of luck. And maybe on your way to Mercury. Think of it this way: A Bugatti Chiron automobile generates 1,479 horsepower. This is more than 7 school buses combined. Does that mean it can get 400 kids to school every day?",
"Short answer: Yes. Your iPhone could do all the necessary calculations and could probably do them in a few seconds. Long answer: Probably not, no. Because this \"amazing fact\" usually relates to the actual Apollo Guidance Computer. You *could* replace the far bigger and faster computers on the ground that did all the mission calculations. Because that's just unspecific maths. As long as you get some numbers out, you're good. But despite it being fairly \"modest\" even for its time, you *couldn't* replace the AGC. Because it's a **guidance** computer. It was built, from the ground up, specifically to control the CM and the LM. It did only that but it did it very, very well and very reliably. So you'd have to find a way to get your phone to talk to all your space ship systems and do it reliably and quickly. I'm no computer engineer but I think the problem would actually be this interface. The necessary calculations would take almost no time at all, but \"translating\" all that input into something the iPhone could work with would either require software or a complex hardware adapter, in both cases, communications would take unacceptable amounts of time and be unreliable. Btw, a very extensive book about the AGC is available for download. I'm not entirely clear about the legality of the source (even though it's ESA), so I won't share it. But just google for \"apollo guidance computer architecture and operation\".",
"Why doesn't every cell phone include [this]( URL_0 ) then?",
"It’s often forgotten that although computers weren’t as powerful as today, NASA didn’t want the most complex computers/systems aboard their rockets. More complicated computers just increases the risk of system failures, which obviously is not acceptable in a mission like landing humans on the moon.",
"Yes and no. It has the computing power for sure, but it certainly lacks hardware requirements. Some of those are obvious (such as it's missing the Saturn V around it to fly there) while others might not be as obvious, such as having independent systems performing the same task to ensure redundancy. One thing to note about the computers running the Apolo program: They were not the most advanced, fastest or best computers available at the time. They were quite far behind on current tech, but they were known to be reliable, had actually been tested during space flight and were simple enough to be understood completely by a ground crew in case of an emergency, which saved both Apolo 12 and 13. The requirements were not \"get us the most computing power per kilogram\", they were more like \"Get us the most reliable stuff you can find for a voyage into the unknown\".",
"Most of it could be done by hand with the right information and training. An iPhone is way more than capable of running the software as far as raw compute power goes. In fact you may be very well able to run the software in browser in an iPhone. You can do so on a PC.",
"Yes your phone could. Just use google moon map and put in your location and then input where you want to land on the moon. You will be given directions to the moon. Then as you travel you can have your phone play Dark Side Of The Moon by Pink Floyd. You can have your phone order moon pies through Amazon. You can google how to make moonshine and make your own moonshine.",
"not exactly, or at least, not precisely. Consumer grade cpu are not quite like the processors in a rocket. There's so much extra stuff to cheapen the system and speed up consumer applications that there's error in both the results and the timing. This is not ideal for the computations done in a rocket, so more reliable systems are used. But yes, your phone can technically have more \"computation power\" by the way of doing more things faster."
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f2zeyz | What stops the robot from clicking the I'm not a robot button? | Technology | explainlikeimfive | {
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"Nothing. Bots can easily click it it. The thing is, while it looks like a simple button, it's actually tracking a number of things about you from the moment you load the page. Your mouse movements, your typing, and even things like your browser version and your IP address. It tallies up all of those pieces of data and uses that to decide if you're a bot or not. If it thinks you look human enough, it lets you through without any fuss. If, however, you look too bot-like it will make you answer those image challenges where you have to click the pictures of cars or stoplights or whatever. (All of which are extremely difficult for AI's to reliably answer, precisely because Google uses images that its own experimental AIs have trouble with) As a practical example, the biggest downside of using a VPN to protect my privacy is that I *always* get those image challenges. Since my VPN gets used by a lot of people (including plenty of bots, no doubt), the system always flags me as \"might be a bot\".",
"Programming a robot to type things, such as trying a bunch of passwords, followed by the Enter key, over and over again, is really easy. Programming a robot to perform image recognition on a display, see where the button is, recognize it for what it is, and provide a simulated mouse-click or touch input to that location is hard. Some robots can do it, but it's a lot harder to make that robot. Those really annoying robot checks where you have to squint to see what letters the malformed colored squiggles inside of the rectangle are supposed to be and type them, or click every picture on the grid that contains crosswalks or stop signs, are nearly impossible to program a robot to do without advanced image recognition and machine learning to the point where it's not worth making the robot.",
"These things are called CAPTCHA which stands for Completely Automated Public Turing test to tell Computers and Humans Apart (Computer Scientists aren't good with the concept of Acronyms). The one's with a check mark actually work by sending some data to Google (who owns reCaptcha), stuff like your mouse movement, your connection details and your cookie history. Google, understandably, doesn't actually publish exactly what data is sent. They then use that to determine if you're likely to be a bot or a human ( for example a bit may move the mouse almost instantly in perfectly straight lines, whilst a real humans mouse movement would be slow and jerky). If they then determine that you're possibly/likely a bot you'll get one of the secondary checks, such as selecting all pictures with stop signs. This is something that's relatively easy to do for humans, but almost impossible for a conventional computer programme (it's doable, and getting easier, with advances in machine learning, but still takes a lot of effort and time to get a program to any level of reliability).",
"The thing is, it can. The other thing is, Google engineers are smart. Have you ever noticed that the I am not a robot button is almost never on the screen initially? You actually have to scroll down to see it. A robot wouldn't have to scroll down. Also, a human had to manually move a mouse across the screen in an imperfect manner which a robot may or may not do. Now you're likely signed in on your Google account. Well Google has a pretty good profile on your browsing habits to check against. All of these things go into deciding whether a human or a robot clicked that button. And if these things Fail,b well then you now have to identify pictures of trees etc etc."
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f35vum | Why aren't there easy to use formats of video that support an alpha channel (similar to a PNG) | Technology | explainlikeimfive | {
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"For videos, color keying tend to be used instead of alpha (So you just replace a specific color like green). [You can find a ton of videos with green screen elements you can replace on the web]( URL_0 ). I think the reason why it is done this way is that you can film green screens, but you can't film alpha. You could replace the green by alpha, but that's just an extra step.",
"There are, they're just not that common. [WebM]( URL_0 ) has been able to do it with VP8/VP9 for years, though annoyingly it regressed with VP1. On the production/pro space, you're likely to find ProRes 4444. Another option is to distribute the video as two files, the color data and a separate monochrome alpha mask."
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f37ayj | Why is Bluetooth not the standard for tv remotes? | Most televisions, i have used use Infrared signals, but why not use Bluetooth? | Technology | explainlikeimfive | {
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"Bluetooth is more complicated and expensive than an IR light bulb and an IR sensor. And the IR light still gets the job done.",
"Bluetooth requires a handshake and a bunch of other more complicated stuff that makes it slower, less reliable, and more expensive. Sure, it has security and bandwidth, but nobody's gonna be streaming audio from their remote to their TV, and most of us aren't worried about hackers changing the channel.",
"In addition to the other replies, Bluetooth uses way more battery than a simple led. So you would need to change batteries way more often or would need to charge it. Nobody would like that.",
"The reasons for using infrared are more practical than technical. IR remotes are cheaper to manufacture. When you are building tens of thousands of units (TVs & remotes) to sell at a certain price point, every penny makes a difference. Legacy - IR remotes came out decades before Bluetooth was invented. The manufacturer has something that works, the R & D costs are already sunk. No need to invent a new system. IR remotes do not require pairing of any sort. Battery life - Bluetooth sucks battery power eventually. Think about how often you replace the battery in tour IR TV remote, compare that to how often you need to recharge the battery in a Bluetooth device. Replacing a battery every 6-12 months is easy."
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f38wkz | Why is there a huge difference from 240p to 360p in the YouTube video quality but then not really much of a difference from 360p to 720p? | Technology | explainlikeimfive | {
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"It’s a matter of hitting “diminishing returns” in terms of your brains ability to do object recognition. At 240p, a lot of things are a lot more difficult to recognize than at higher resolutions. At 360p and 480p, you can pretty well recognize all of the important parts of a picture, and your brain will make it seem like there is a massive jump in quality. Higher resolutions add additional clarity to the image, but generally not to the extent that it’s bringing into focus key elements of the picture. The higher the resolution, the better you can see the minor details.",
"It really depends on what you're looking at and how much definition it needs. If an object cannot be distinguished with the little resolution available at 240p, but can at 360p, it looks so much better. If it gets sharper going from 360 to 720, it still looks better, but it's not as drastic as making it visible.",
"Your eye notices more difference between a 5 pixel image and a 10 pixel image than between a 900 000 pixel image and a 1 million pixel image. Here are the real values for a 16:9 monitor (most common aspect ratio nowadays): 2160p: 3840x2160. 1440p: 2560x1440. 1080p: 1920x1080. 720p: 1280x720 = 921 600 pixels. 480p: 854x480 = 409 920 pixels. 360p: 640x360 = 236 160 pixels. 240p: 426x240 = 102 240 pixels."
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f3akd8 | How does an electric guitar pick up only sounds from the strings and not speech for an example? | Edit: Thanks for all the answers < 3 | Technology | explainlikeimfive | {
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"An electric guitar pickup is essentially thousands of turns of thin copper wire wound around a magnet. When a steel string vibrates near the pickup, it will disturb the magnetic field. This induces a small electric current in the copper wire, which is then amplified. An electric guitar needs steel strings to work. Nylon strings will not work on an electric guitar. Speech is just pressure changes in air, creating no disturbance in the magnetic field, so it will not be picked up. However, if a speaker (in a toy laser gun for example) is brought near the pickup, the guitar will pick up the signal because the speaker itself works using electromagnetism.",
"It doesn't. An electric guitar has magnetic sensors that detect how the strings are moving, by detecting disturbances in a magentic field under the string.",
"In a normal microphone there is a diaphram which gets moved by the changes in air pressure and then the electromechanic components of the different types of microphones will record the movement of the diaphram. However in an electric guitar there is no diaphram but the pickup is detecting the movements of the strings directly. As the strings of a guitar is quite narrow and are strung quite taught they do not really pick up much vibration from the changing air pressure from the sound of your voice or other instruments. This way the guitar pickup is only picking up the sounds from the strings.",
"The real question to me is, how DO they still pick up your voice if you yell into it? If you have a lot of gain and turn it up, you will hear the voice, and it’ll do it with the strings muted directly over the pickups so they aren’t vibrating."
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f3e58y | Why do mixers interfere with old tube TV signal? | As a kid i remember always watching the tv get a distorted signal whenever my mom was using the mixer. Why is that? | Technology | explainlikeimfive | {
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"A mixer is basically a fair-sized electric motor. Electric motors work in various ways, but they all utilize rapidly changing electric and magnetic fields. They tend to be \"noisy\" in terms of how much stray electromagnetic radiation they emit. And radio is just that, electromagnetic radiation. (In the case of radio, a color that is so deep red that our eyes can't see it.) Radios and TV can pick up these signals if the mixer is close enough, and try to turn them into video/audio. Of course, that doesn't work well. If a mixer is very close to an old CRT TV, the magnetic fields can directly impact the operation of how the tube gun shoots electrons at the screen. But it typically would need to be fairly close for that to happen.",
"It's actually the commutators on the motors, old electric motors have commutators which are brushes that touch spots as the motor moves causing the wires to get connected and disconnected as the motor operates. When this happens there is typically a small spark (on many devices you can look in and see these sparks). Anyways, sparks create broad range RF, [basically a spark gap transmitter]( URL_0 ), so these sparks act as small radio transmitters that interfere with all radio devices, with old TV being one of the common ones. Now you probably use cable TV which shields the signal inside a wire so it's not an issue. Also, more attention is paid to reducing the sparks, they interfere with modern circuit breakers that have spark detection (AFCI breakers). We have brushless motors that are truly spark-less, and these are used in most of the higher end equipment."
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f3edsv | How does the “pulse” rate for people with artificial hearts adjust with their emotions or adrenaline? | Technology | explainlikeimfive | {
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"They don't. People who get artificial hearts are usually in pretty dire shape and deemed unsuitable for traditional transplants. They won't be playing basketball or making passionate love. There is some current work on pumps that react to demands, but nothing commercially available.",
"They don't. You just get the heart rate you are given and it's better than being dead. Like it's not an ideal situation and has a lot of issues if you exert yourself and with emotional response stuff but when your other option is not having a heart people generally are okay with the trade off.",
"My brother has an LVAD and not only does it not adjust for emotional response, it doesn’t slow when he sleeps. He hardly sleeps at all. It is not optimal. Someone else mentioned this, with these devices it would be very difficult to die. He has had a massive stroke and his quality of life is pretty awful, but he can’t really die. It’s strange.",
"it does not adjust on its own. It’s set at determined rate based on what they need to sustain life before they leave the hospital. I work on a transplant unit and starting to work with Syncardia, a total heart replacement (TAH), and the pulse rate is set to what the body needs. The patients will have follows ups for life and adjustments will be made as the body changes in one way or the other If you want to read more here’s a link to the one we use. [Syncardia]( URL_0 )",
"1) Modern pacemakers (not artificial hearts, but implanted devices that help people who have improper conduction in their heart and thus don't have a fast enough heart rate) can kind of fake it; if they notice the pacemaker is moving a lot (breathing fast, jostling due to walking fast or what have you) they speed up the rate at which the pacemaker fires. 2) In response to your question about what happens when they exert themselves if they can't match their heartrate to demand: they get tired and short of breath quickly. (\"Dyspnea on exertion\" is kind of a classic sign of a lot of kinds of poor heart function)"
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f3fsur | How come apps will sometimes refresh every single time I open them, even if I just switched between apps for a moment, but other times apps will stay exactly where I last scrolled to for a day or more? | Technology | explainlikeimfive | {
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"Depends on the coding of the app. Like people have different reactions to certain things. Apps are programmed to respond to certain events, click open scroll",
"Android developer here, with a bit of iOS experience. TLDR: it's up to the developer's discretion, as we're given the option to save everything just how you left it or to clear everything, depending on security or privacy concerns. There's a process called the app lifecycle that triggers when an app starts, stops, is moved to the background, or is stopped completely. There are lifecycle triggers developers can use to save or clear data when those events occur. That sequence is (roughly) create - > start - > resume and then pause - > stop - > destroy. For instance, you launch a new application, which shows a home page you've previously logged into. In the process it fires the onCreate, onStart, and onResume triggers. The developer setup the foundation of their app in onCreate, checked storage for your credentials and logged you in during onStart, then started up small animation that plays on the page in onResume. Now, you change applications, or just go back to the home screen. This fires the onPause trigger, which is the opposite of onResume. All the developer needs to do here is stop that animation from looping, because it would use unneeded resources to run in the background when you can't even see it. Then the onStop trigger is fired, which is the opposite of onStart. The dev will save your credentials to storage, so you can be logged in when you go back to the app. But, the app is still running, so onDestroy (the opposite of onCreate) is never called. Now, if the app we were writing was more secure, like a bank app, a trade platform, or even a diary, we may not want to leave you logged in, so in onStop we'll log you out and clear your credentials, or at least flag you as needing to reauthenticate with biometrics to prevent someone from browsing your stuff when you put your phone down."
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f3gnav | What is a 9980 port and why isn't it secure? | Technology | explainlikeimfive | {
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"If IP addresses are houses, ports are sort of like apartment numbers. I can send a message to ip X, but without the port nobody knows *who* at X is supposed yo recieve it. Port 9980 is, AFAIK, not commonly used by anything. However, in general having an open port can increase security risk because firewalls block all other traffic. Under nirmal circumstances, someone sending data to port 9980 would get bounced by my routers firewall: if I open that port, the message can now get through to my PC. That being said, something on my PC has to be *listening* on that port in order for the message to do anything, so the security risk is minimal."
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f3i4ml | - how does a coffee maker turn room temperature water into scalding hot liquid so quickly | Technology | explainlikeimfive | {
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"It doesn't work like a kettle, trying to warm a big tank of water up at once, it draws water up through a tube, and heats the water in that tube only. The result is hot water rapidly, but it's not being delivered at a very high volume. That's how it does it. A lot of water at once hot takes time. A small amount at a time hot, can be done very quickly when you're running off wall power.",
"That's also how it pumps it as well. The tiny bit of hot water is less dense and rises to be replaced by fresh cold water."
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f3k0eg | Why is it that most if not all computers need to restart/close down while performing a software update? | Technology | explainlikeimfive | {
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"The biggest reason is that files that are in use cannot be changed/deleted (open a file in word, then try to delete the file from explorer, it won't let you). Updates change the files that they need to change, but if they have to change a file that is in use, they'll set it up so that during the reboot, the file will get changed, after it has been stopped, either on the way up or on the way down.",
"It is like changing a part on a car that is moving. You have to stop and restart the car with after the new part is installed."
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f3koug | How can captcha know I am not a robot from just a click? | Technology | explainlikeimfive | {
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"When you click the button, it sends information about your browser and about how you were using the web page. How long you were on the web page before you clicked the captcha button, information about how you scrolled through the page, how your mouse moved and other 'odd' information. You are very different from a computer, so the data you generate will be very different from a computer bot. The CAPTCHA programmers showed a program what 'human' data looks like, and what computer data looks like, and taught it to spot the difference."
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f3pgfn | How does a computer know what time it is when turned on? | Technology | explainlikeimfive | {
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"If you look on a computer motherboard, you'll find a button cell battery (C232). This provides continuous power to a small memory chip called the CMOS which, amongst other things, keeps track of the system clock."
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f3v7mt | How does the tiny rubber ring around a water resistant phone's SIM tray hold back all the water? If you pinch or sit on it, is it broken? | I get how the charge port and buttons are protected, you can't remove them. But when you change the SIM, there's just a small strip of soft gooey material near the top of the tray. It looks like it can't possibly protect against the force of dunking the entire thing underwater. Is it the weakest part of the waterproofing, does it wear out? | Technology | explainlikeimfive | {
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"If it's designed correctly, it forms a reasonable seal. And if immersed in water, the pressure of the water should slightly deform the rubber gasket to make an even better seal. They don't exactly \"wear out\" like some things do. But with age, rubber tends to lose its elasticity and the seal quality will degrade. Just deforming it mechanically a bit shouldn't hurt it, unless you pinch it so hard that it permanently has a crease or other damage."
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f3zrqs | Why do older pc games default to the lowest possible setting when auto detecting newer computer systems? | For example, I have an i7 with a 1080 ti but Oblivion seems to think I am playing on my toaster when I do the initial start up. | Technology | explainlikeimfive | {
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"Probably because the game detects something that isn't known or that it hasn't the ability to read the characteristics of so it defaults to a low configuration. Basically the hardware is too new for that piece of software.",
"The games don't test the capabilities of the hardware, only the model number. While it may be obvious to you that the new model number is new, to the game it's simply unknown. The way marketing plays with model numbers, there's no reliable way to forecast hardware performance based on them alone."
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f45gw0 | why appliances such as an old generation TV or a remote which are not working properly start functioning correctly when hit? | Technology | explainlikeimfive | {
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"The russian way of fixing things is not a consistent way to fix things. It could help separating pieces that shouldnt and remove a power issue momentarily but i dont recommend hitting anything."
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f46q55 | How TV and radio broadcasters can tell how many viewers and listeners they have at anyone moment? | Technology | explainlikeimfive | {
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"They usually can't. Radio is one way, same as gps and tv. But now, tv is over Internet, which allows communication and thus counting your viewers and estinating the rest of it.",
"I think radio relies on surveys to estimate their number of listeners, TV would have done the same before internet transmissions.",
"In the US and UK it's done by market research agencies like Nielsen. They take a sample of people and monitor what they consume and then extrapolate that to the larger demographic. So they might ask 100 women aged 50 to 65 to keep a diary of every TV show they watch and then they'll use that to say '20% of this group watch Mrs Marple' It's the same principle used in medical research, you can't test the whole population so you take a representative group and use that as a proxy.",
"Years ago in the UK they could tell by a spike in the grid and a surge in energy demands as people boiling the kettle at the same time during advertising or end of a show, but times have changed massively since then so I don't know about nowadays.",
"Nielson Families..in the USA for television: A private and trusted firm picks a certain number of households. They give these household a box that monitors the television habits, when, what network, what show ect. The family gets a few bucks a month. Neilson also keeps demographics on the families they select and use the data to make generalizations about television habits of Americans. The same method a scientist would use. A simple cross section of a sizable enough sample. Networks pay Nielson for their data and use the data to show potential advertisers the value of running an ad on their network at a certain time or a certain show. I'm sure there is a Wiki page about it and I'm sure I got some things wrong.",
"It's measured by a company called Nielsen. The measurements for TV and Radio are done in completely different ways. I've worked in radio so I can speak to that. In the OLD days, it was done via diary. Arbitron (later bought out by Nielsen) would send out booklets to random households in the listening area and give them a small amount of money to fill out, in detail, every station they listened to, at what time, and for how long. That household's data was then multiplied by the population in various demographics and you'd have an idea of how many people were listening to what. In reality it was wildly inaccurate and you might end up with one family swaying the survey by 10% or more, changing the distribution of millions of dollars of ad revenue. This led to radio stations coming up with cheesy, rhyming slogans (\"kiss fm is your vacation station\") because they were trying to imprint their brand on you. People were terrible about filling out their diaries, much of the time they'd fill them out after the fact, generally just before they had to be turned in. So you tricked people into remembering your station so they'd write your name down. That's why you had so many cheesy DJ names and station slogans, the idea was to be top-of-mind. Nowadays they use what's called a People Meter, which is a little device that basically has a thing similar to Shazam built in. It can tell what station is on in the background because there are hidden, inaudible tones in each station's broadcast. It still is only a small sample multiplied up to the general population, but it at least gives you data more quickly than waiting a whole quarter for diaries to be collected, tabulated and compiled. And there's less trickery to get you to remember a station's brand, now it's more about getting you to tune in more often and stay for longer, hence a lot of *appointment listening,* \"Tune in at 7:10am for your next chance to win!\" and teases, \"we'll give away another pair of tickets in the next 15 minutes so don't move.\""
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f48hez | How do induction cooking work | I watched my mom cooked food with the induction cooktop several times but please explain how does it work, thanks | Technology | explainlikeimfive | {
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"Electrical friction essentially. Create a changing magnetic field under a metal pot. The electrons in the pot see the magnetic field and try to line up in it. The field keeps moving though and the electrons can’t keep up. They get dragged a bit and give off heat. Do this process rapidly and frequently enough and your metal pot starts to heat up.",
"There are coils of wire underneath the cooktop. When the power is switched on, the coils of wire are fed alternating electrical signals, which causes a magnetic field. When something ferrous (steel) is placed on the cooktop, the steel acts like a one-turn transformer short-circuited. Electricity is induced in the steel, but has no-where to 'go' so it turns into heat.",
"The heating occurs because an electric current flows in the pot that you put on the stove. If you put a glass pot on the stove, no heating occurs because the glass is a very poor conductor and charge will not flow, so no heating. So how does the stove get electric current to flow in the pot without an electrical connection? This is the induction part. A changing magnetic field will produce an electric field. An electric field will apply a force to the electrons in the conducting metal pot, which causes the current to flow, and this current is what causes the heating. To produce a changing magnetic field, under the stovetop there is a coil of wire. The current in the wire coil produces a magnetic field. If we flip the direction of this current, the direction of the magnetic field will also flip. This changing magnetic field is what induces the electric field. If there is no pot on the stove, the induced electric field is still there, but there is nothing to carry the electric current so there is no heating. You can put your hand on the stovetop and it will be cool, since the induced electric field won't cause a significant electric current in your hand. A few extra details/notes: \\- the scientific principle of induction at work here is called \"Faraday's Law\" \\- the faster the magnetic field is changed, the larger the induced electric field, so the larger the current and so more heat \\- the larger the current in the coil under the stovetop, the larger the magnetic field, and thus the larger the change when it filps direction, so the larger the current in the pot and so again, more heat \\- this mechanism is the same principle by which phone with a \"charging pad\" can be charged without \"plugging in\" (wireless charging). Except the induced current in the phone is captured and used to charge the battery instead of heating the pot \\- this mechanism also works to read credit cards or other cards with magnetic bar codes. When you \"swipe\" your card, your motion causes the magnetic field in the card reader to change, which induces a flip-floppy current in the bar code reader. This flip-floppy signal is read and converted into your card number or other information. \\- If we didn't know about Faraday's law, our lives would be very, very different. We would not have electricity piped to our homes. We may have batteries running things, but sooo many things depend on Faraday's law that I personally rank it up there with the germ theory of disease in terms of importance and impact on humanity. Just a few corrections from other posts: \\- the pot does NOT need to be ferromagnetic, like iron. It just needs to conduct. So copper pots will work. \\- the electrons do have intrinsic magnetic fields and they do try to line up with the magnetic field. But this does nothing to help the heating or the electric current. The actual desired effect is that they feel a force in the direction of the electric field, and this movement is the electric current that causes the heating. \\- the magnetic field does not create the charge. The charges (electrons in the metal) are already there. The changing magnetic field creates electric fields, which move the charges.",
"So I am going to try this ELI5... You probably know about electric engines. When you run an electric current through the engine, it creates a shifting magnetic field which causes a magnetic metal to move. This turns electricity into movement. You may also be more familiar with electric stoves. In this case they run electricity through coils so that the electricity turns into heat. These two pieces come together in a rather unique way on a induction cooktop. First, we use the first part, except in reverse. Rather than using electricity to create the magnetic field, we use a magnetic field to create electricity. This is why if you place a plastic pot on an induction stove, nothing will happen, because it cant interact with the magnetic field. When you do put a proper pot on an induction cooktop, that magnetic field creates an electrical charge, however we use the same properties of an electric stove here. The charge does not stay as electricity, but rather the flow creates heat, just like it does in an electric stove. So in short an induction cooktop actually turns your pan into the heating element, which is why the stove itself never really gets very hot comparatively. It directly heats the pat which then directly heats the food."
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f4eb0m | Why is it when you try to download an android app, it asks you for way more space than the app takes? | Example: You have an android device with 4GB of storage, and you have 500MB left. You want to download an app that's 60MB. You get a message in the Playstore asking you to free up more storage, even though you already have the space. Sometimes, even smaller apps ask for vast amounts of storage (i.e: a 5MB app asking for 200MB). Why is this? | Technology | explainlikeimfive | {
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"Same reason the dresser you pick up at Ikea is smaller when it's in it's unassembled box than the display Products are packaged for distribution, not in it's immediately functional State. It needs to be unpacked, assembled and installed"
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f4f69c | Why do multimeters have scales which go up to 1.999 mV or 199.9 mV rather than 9.999 mV or 999.9 mV? | Whenever I've used a multimeter (admittedly only cheap crappy ones) they always have scales which go up to 199.9 of a given unit, where the unit can be changed, eg you could set them to a scale max of 199.9 uV, or 1.999 mV or 199.9 mV or 1.999 V (and the same with ohms or amps). Why do the scales always go up to just under 2 (or 200), rather than being say, 999.9 mV | Technology | explainlikeimfive | {
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"The most significant digit on the LCD only has the segments to display a 1. It's cheaper to make that way."
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f4iovd | How was World War 2 footage captured? Especially the ones that seemed to be amid actual battles. Were these reporters? Were there rules in place agreed upon by all sides that these folks would not be killed or captured? | Technology | explainlikeimfive | {
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"text": [
"Combat Camera They were soldiers who were issued cameras and recording gear for the purposes of documenting the battles. Some was sent home for propaganda footage and shown before movies in theaters They serve in all branches of the US military and record footage and images to this day.",
"There have been war corespondents for years, going back to the Crimean War. Mathew Brady took still pictures during the US Civil War. US Army sent many top Hollywood directors into combat [see movie '5 Came Back'] Both sides wanted combat footage for training and propaganda purposes. Civilian corespondents had special patches on their uniforms to ID themselves. 'The First Casualty' is a good non-fiction account of reporters and camera men over the decades.",
"Combat photographer is a dangerous job, but they have been in most wars since we developed cameras. They are not offered the same protection as medics or Chaplains, so they are treated like any other soldier.",
"They would have been killed or captured just like any other people on the front lines. All sides wanted propaganda footage though, in the early days of cinema, the impact of moving images would have been huge, so I suppose higher - ups would have felt it was a risk worth taking.",
"For the US Forces they were enlisted cameramen and not reporters. Many of them were already involved in film and many of them like John Ford went onto direct many Hollywood movies after the war. They didnt carry guns but were right at the front lines and many were killed.",
"A lot of battle footage was \"recreated\" after the main battle had finished for safety sake. e.g. in Frank Capra's Tunisian Victory was presented as real battle scenes, much was shot in America [ URL_1 ]( URL_0 )"
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f4np3s | How does a cruise missile know where to go? | Technology | explainlikeimfive | {
"a_id": [
"fhrvbdb",
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"text": [
"Maps and cameras! Depends on the particular missile, but it probably has GPS, an inertial guidance system and a terrain matching camera. It has a microprocessor onboard with a flight plan, waypoints and a map of the area and it flies the programmed route. It might also have some other back-up systems or be steerable remotely.",
"There are lots of fancy systems as mentioned in other posts... including GPS, but the main component is the same as any other flying odject (include the ones that took us to the moon and back)... IGS or Inertial Guidence System. Basically it is a bunch of gyroscopes connected to measuring devices and a simple computer. You program in where it is starting from, and where it is going to, and its weight and so on... and then you let it rip. The IGS can tell by the amount force excerted in every direction and for how long, exactly how far the missile has travelled and in what direction. To give you an idea of how accurate it is... back in the 60's when it was developed, the very first test flight went from New York to LA with the windows blacked out and no other method of nav on board, and when they thought they were close they pulled off the curtains and found themselves within a couple of miles of LAX. Obviously it has improved since then. The Cruise has another system that uses radar etc for tracking the profile of the ground so that it can fly really low... and a third system using cameras to track the target right at the end which they can use for both stationary and moving targets."
],
"score": [
18,
5
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f4psoh | When browsing the internet on a phone, why does the screen always seem to jump up or down at the exact same moment you click, causing you to click the wrong link? | So; I know the screen jumps up and down a bit as things like ads load. But, it seems like more often than not everything is totally stationary and done loading, then in the exact moment I try to click a link, the screen jumps again causing me to click something totally different. Is it in my head? Why does this happen? | Technology | explainlikeimfive | {
"a_id": [
"fhs5ifi",
"fhsaazg"
],
"text": [
"They probably do it on purpose because they get money per how many people click on the ads.",
"Its possibly just confirmation bias. You remember the times it does it (\"dang it did it again!\") But you're less likely to remember the times it works as intended. Pay special attention for the next few hours of scrolling and count how many times it actually happens. You may be surprised how small a proportion it really is. Still sucks when it happens though!"
],
"score": [
13,
7
],
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f4qhv0 | I don't understand graphics optimization, can you guys help me? | I dont understand that some PC games like Witcher 3 or Hellblade Senua's Sacrifice have awesome graphics and don't too much pain for PCs but some old or meh graphics games make PC sounds like a plane and drops FPS (heating etc.). Everybody says because that games optimized very well but how and why all game devs do that? Can you guys help me? Ps: I am not native so sorry for my English. Thanks | Technology | explainlikeimfive | {
"a_id": [
"fhshkpn"
],
"text": [
"There are smart ways of doing things, and silly ways of doing things. Same applies to coding. Smart takes effort, money, skill and time so sometimes shortcuts were taken or cheats were used to take advantage of a feature that was fast on a particular popular graphics card or processor that was around at the time. Rather than try to make the game work in a way that would work the same on all PCs, all cards, in all combinations, some programmers just throw code at the problem until it works, and then ship the game. And the way that we do things changes over time. Just in OpenGL, we've gone from having to use immediate mode, to display lists, to vertex lists, to shaders, to compute shaders, etc. Modern cards aren't optimised for immediate mode and just \"emulate\" it, in essence. It's like making a car. You can make a car that everyone can drive, that can drive on every road, that's fast and economical. Or you can just throw out something that you have to squeeze into, that large people can't drive, that only works on side-streets and can't go on the motorway, or burns so much fuel that it's impractical but gets you where you want to go. There is no one \"way\" of coding. There's an ideal, which changes over time, and there are myriad ways to get there. Coding is far more akin to writing a book, or an instruction manual. If you wanted to write a book about how something worked, there are MILLIONS of different ways to write that book... but some people will write books that are easier to understand, some will write books that are more accurate, some will write books that don't even describe reality, some will write horrendously so you can barely understand them even if you're correct, and some might even write the book in Chinese which might be perfect for some people, and terrible for others to read. Games are millions upon millions of lines of code, often running on dozens of platforms, with sometimes millions of potential hardware combinations (e.g. CPU, RAM, graphics card, motherboard bus speed, etc.). A good, well-optimised game will work the best it can for everyone. But a game that's badly coded, rushed, or done on a small budget will more likely only work on a handful of combinations with any decent speed because it will assumptions about the kind of hardware it's running on. This is also why console ports are often terrible - they were written by one team who were told \"This will only ever run on Playstation 4\", so they heavily optimise everything from the screen size to the number of things in memory to the speed which they pull stuff from the disk or Internet to those assumptions. Then a year later some other poor sod gets nowhere near the same amount of time or budget but is told \"Make this work for every PC\"."
],
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8
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"text_urls": [
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f4qvxz | Why can't HDMI 2.0 support 4:4:4 RGB HDR? | If HDMI 2.0 supports 18 Gbps, why is it said to "lack" the bandwidth necessary to stream 4:4:4 RGB HDR video? I know Bluray is 80mbps, and that's hardly anywhere near the 18Gbps? | Technology | explainlikeimfive | {
"a_id": [
"fhsn667",
"fhsilth"
],
"text": [
"Why would Blu-ray be 80Mbps? I think you might be confusing compressed bit-rate (i.e. the speed the compressed data comes off the disk) versus uncompressed (i.e. the speed at which video data has to be fed to the TV to show without skipping a frame). 1080p, RGB at 24 fps progressive alone is 1.19 Gbps. [ URL_0 ]( URL_0 )",
"4k video at 60fps with a color depth greater than 8 bits per channel requires at least 20gigabits per second to transmit an uncompressed video stream. This exceeds the bandwidth specified by hdmi2.0"
],
"score": [
6,
3
],
"text_urls": [
[
"https://toolstud.io/video/bitrate.php"
],
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| [
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|
f4ujpg | How do you tell a computer what time it is? You can tell a mechanical clock to tick every second using physics but how do you do the same to a non-moving electronic device? | Technology | explainlikeimfive | {
"a_id": [
"fhtqjud",
"fhtr356"
],
"text": [
"You do it with a quartz, which emits a pulse at specific intervals when a certain voltage passes through it.",
"Inside every digital clock is a crystal that physically resonates like a tuning fork when it is excited by electric pulses. This resonance can also generate electricity, so when the crystal reaches its resonant frequency it affects the circuit driving it and syncs up the electric waveform to its ringing. The circuit can then count the cycles of this waveform - each X cycles one second passes. Crystals are usually 25 to 5 ppm (parts per million) accurate, so you'd get some drift, but the computer sync up its own idea of what time it is to time services through the internet. Those use much more accurate atomic clocks."
],
"score": [
8,
4
],
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|
f52vg9 | What are analog cameras and how are they different from other types of cameras? | Technology | explainlikeimfive | {
"a_id": [
"fhwdbaa",
"fhwdhau"
],
"text": [
"Analogue cameras is what film cameras became named when digital cameras came out. Film instead of sensor and memory cards.",
"So analogue Cameras tend to be what the mass see as \"old\" cameras, they write the light information to a 35mm (or other size) film, this is called a negative, which is then used to transfer onto photo paper. Interesting stuff really, if you're a student or any local photoclubs, definitely go and check out a printing session, lots of fun!"
],
"score": [
3,
3
],
"text_urls": [
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} | [
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| [
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|
|
f56m9s | Why can't we send unmanned craft further into space? | Technology | explainlikeimfive | {
"a_id": [
"fhwwgbc"
],
"text": [
"We can. For example, the voyager probes; they're going to keep on going forever until they hit something."
],
"score": [
6
],
"text_urls": [
[]
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} | [
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| [
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|
|
f575lo | How do speakers work when you increase or decrease the sound? | Technology | explainlikeimfive | {
"a_id": [
"fhwyyst"
],
"text": [
"Speakers work by using an electric signal to move a magnet, which moves a cone, which vibrates the air, which you perceive as sound The speed at which the signal cycles determines the frequency, or the tone. The amount of power determines how hard the magnet is pulled, which determines how hard the air is vibrated, and how loud it is"
],
"score": [
3
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"text_urls": [
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f58soj | How can the internet be running out of IP addresses? | I read an article that says “amassing IP addresses has become a lucrative business because the American internet registry and its counterparts around the world are running out of unique addresses—or at least the current version, IPv4, of which there are about four billion. A switch to the next generation is under way, which will make billions more addresses available, but it will take years to complete.” Why is it so hard to just type a code that creates more addresses? | Technology | explainlikeimfive | {
"a_id": [
"fhx7641",
"fhx7584",
"fhx9l42"
],
"text": [
"an ip address is 4x 8 bit numbers. that's it. exactly how they're tallied and how stuff works is more complicated - there are entire qualifications half of which are taken up by various forms of subnetting. the highest value you can have in an 8 bit number is 255; it then overflows back to 0. 255(U8BIT) + 1(U8BIT) = 0(U8BIT). The \"U\" there stands for unsigned, basically meaning it cannot be negative. In short, the IP (internet protocol) only exists as a set of rules. There isn't one single IP server that all the others are subservient to or whatever - it's just a set of protocols that we all follow if we want to communicate concisely. We can't add an address higher than 255.255.255.255 because (among other reasons lol) that would overflow it by one bit somewhere. that would make an ip address 3x 8 bits and 1x 9 bits. How can you tell it's either one just by receiving the data over a data line? you wouldn't know where to stop reading the address considering that data sent over these lines is literally just a series of numbers. this is a much condensed version of things so be sure to reply and tell me what you'd like for me to elaborate on - there's no way the above two paragraphs can be enough for you to understand from scratch. also, we don't give every single device an ip address. we use something called NAT to facilitate ip connectivity on multiple devices connected to one gateway which has only one ip address. if we gave every device an ip address and didn't subnet anything we would probably have run out before the year two thousand.",
"The code to support more addresses, called IPv6, has been standardized and deployed since 1998. The problem is that in order for it to work, everybody has to update their software. That it super hard, as there are 1B devices that have to be updated. Devices that aren't updated won't be able to access the services, and nobody wants to tell someone \"no Internet for you!\".",
"IPv4 is a big neighborhood, and people kept building more and more houses. Each house needs a house number so that they can get mail, but there's only a certain amount of space in the neighborhood before every plot is taken, and there's no more room to build another house. IPv6 is a *much* bigger neighborhood, and it'll let us keep building houses and giving them house numbers for a long, long time. Before we can start delivering mail there, though, we need to get every post office to agree that they'll deliver mail to those new house addresses."
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